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diff --git a/Build/source/texk/web2c/hitexdir/htex.w b/Build/source/texk/web2c/hitexdir/htex.w deleted file mode 100644 index 252179780ac..00000000000 --- a/Build/source/texk/web2c/hitexdir/htex.w +++ /dev/null @@ -1,29213 +0,0 @@ -% This file is part of HINT -% Copyright 2017-2021 Martin Ruckert, Hochschule Muenchen, Lothstrasse 64, 80336 Muenchen -% -% Permission is hereby granted, free of charge, to any person obtaining a copy -% of this software and associated documentation files (the "Software"), to deal -% in the Software without restriction, including without limitation the rights -% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell -% copies of the Software, and to permit persons to whom the Software is -% furnished to do so, subject to the following conditions: -% -% The above copyright notice and this permission notice shall be -% included in all copies or substantial portions of the Software. -% -% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR -% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, -% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE -% COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, -% WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT -% OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN -% THE SOFTWARE. -% -% Except as contained in this notice, the name of the copyright holders shall -% not be used in advertising or otherwise to promote the sale, use or other -% dealings in this Software without prior written authorization from the -% copyright holders. - -% The HINT program is derived from Donald E. Knuth's TeX and the -% subsequent e-TeX extension of TeX. - -% e-TeX is copyright (C) 1999-2012 by P. Breitenlohner (1994,98 by the NTS -% team); all rights are reserved. Copying of this file is authorized only if -% (1) you are P. Breitenlohner, or if (2) you make absolutely no changes to -% your copy. (Programs such as TIE allow the application of several change -% files to tex.web; the master files tex.web and etex.ch should stay intact.) - -% See etex_gen.tex for hints on how to install this program. -% And see etripman.tex for details about how to validate it. - -% This program is directly derived from Donald E. Knuth's TeX; -% the change history which follows and the reward offered for finders of -% bugs refer specifically to TeX; they should not be taken as referring -% to e-TeX, although the change history is relevant in that it -% demonstrates the evolutionary path followed. This program is not TeX; -% that name is reserved strictly for the program which is the creation -% and sole responsibility of Professor Knuth. - -% Version 0 was released in September 1982 after it passed a variety of tests. -% Version 1 was released in November 1983 after thorough testing. -% Version 1.1 fixed ``disappearing font identifiers'' et alia (July 1984). -% Version 1.2 allowed `0' in response to an error, et alia (October 1984). -% Version 1.3 made memory allocation more flexible and local (November 1984). -% Version 1.4 fixed accents right after line breaks, et alia (April 1985). -% Version 1.5 fixed \the\toks after other expansion in \edefs (August 1985). -% Version 2.0 (almost identical to 1.5) corresponds to "Volume B" (April 1986). -% Version 2.1 corrected anomalies in discretionary breaks (January 1987). -% Version 2.2 corrected "(Please type...)" with null \endlinechar (April 1987). -% Version 2.3 avoided incomplete page in premature termination (August 1987). -% Version 2.4 fixed \noaligned rules in indented displays (August 1987). -% Version 2.5 saved cur_order when expanding tokens (September 1987). -% Version 2.6 added 10sp slop when shipping leaders (November 1987). -% Version 2.7 improved rounding of negative-width characters (November 1987). -% Version 2.8 fixed weird bug if no \patterns are used (December 1987). -% Version 2.9 made \csname\endcsname's "relax" local (December 1987). -% Version 2.91 fixed \outer\def\a0{}\a\a bug (April 1988). -% Version 2.92 fixed \patterns, also file names with complex macros (May 1988). -% Version 2.93 fixed negative halving in allocator when mem_min<0 (June 1988). -% Version 2.94 kept open_log_file from calling fatal_error (November 1988). -% Version 2.95 solved that problem a better way (December 1988). -% Version 2.96 corrected bug in "Infinite shrinkage" recovery (January 1989). -% Version 2.97 corrected blunder in creating 2.95 (February 1989). -% Version 2.98 omitted save_for_after at outer level (March 1989). -% Version 2.99 caught $$\begingroup\halign..$$ (June 1989). -% Version 2.991 caught .5\ifdim.6... (June 1989). -% Version 2.992 introduced major changes for 8-bit extensions (September 1989). -% Version 2.993 fixed a save_stack synchronization bug et alia (December 1989). -% Version 3.0 fixed unusual displays; was more \output robust (March 1990). -% Version 3.1 fixed nullfont, disabled \write{\the\prevgraf} (September 1990). -% Version 3.14 fixed unprintable font names and corrected typos (March 1991). -% Version 3.141 more of same; reconstituted ligatures better (March 1992). -% Version 3.1415 preserved nonexplicit kerns, tidied up (February 1993). -% Version 3.14159 allowed fontmemsize to change; bulletproofing (March 1995). -% Version 3.141592 fixed \xleaders, glueset, weird alignments (December 2002). -% Version 3.1415926 was a general cleanup with minor fixes (February 2008). -% Version 3.14159265 was similar (January 2014). -% Version 3.141592653 was similar but more extensive (January 2021). - -% A reward of $327.68 will be paid to the first finder of any remaining bug. - -% A preliminary version of TeX--XeT was released in April 1992. -% TeX--XeT version 1.0 was released in June 1992, -% version 1.1 prevented arith overflow in glue computation (Oct 1992). -% A preliminary e-TeX version 0.95 was operational in March 1994. -% Version 1.0beta was released in May 1995. -% Version 1.01beta fixed bugs in just_copy and every_eof (December 1995). -% Version 1.02beta allowed 256 mark classes (March 1996). -% Version 1.1 changed \group{type,level} -> \currentgroup{type,level}, -% first public release (October 1996). -% Version 2.0 development was started in March 1997; -% fixed a ligature-\beginR bug in January 1998; -% was released in March 1998. -% Version 2.1 fixed a \marks bug (when min_halfword<>0) (January 1999). -% Version 2.2 development was started in Feb 2003; released in Oct 2004. -% fixed a bug in sparse array handling (0=>null), Jun 2002; -% fixed a bug in \lastnodetype (cur_val=>cur_val_level) -% reported by Hartmut Henkel <hartmut_henkel@@gmx.de>, -% fix by Fabrice Popineau <Fabrice.Popineau@@supelec.fr>, -% Jan 2004; -% another bug in sparse array handling (cur_ptr=>cur_chr) -% reported by Taco Hoekwater <taco@@elvenkind.com>, Jul 2004; -% fixed a sparse array reference count bug (\let,\futurelet), -% fix by Bernd Raichle <berd@@dante.de>, Aug 2004; -% reorganized handling of banner, additional token list and -% integer parameters, and similar in order to reduce the -% interference between eTeX, pdfTeX, and web2c change files. -% adapted to tex.web 3.141592, revised glue rounding for mixed -% direction typesetting; -% fixed a bug in the revised glue rounding code, detected by -% Tigran Aivazian <tigran@@aivazian.fsnet.co.uk>, Oct 2004. -% Version 2.3 development was started in Feb 2008; released in Apr 2011. -% fixed a bug in hyph_code handling (\savinghyphcodes) -% reported by Vladimir Volovich <vvv@@vsu.ru>, Feb 2008. -% fixed the error messages for improper use of \protected, -% reported by Heiko Oberdiek -% <heiko.oberdiek@@googlemail.com>, May 2010. -% some rearrangements to reduce interferences between -% e-TeX and pTeX, in part suggested by Hironori Kitagawa -% <h_kitagawa2001@@yahoo.co.jp>, Mar 2011. -% Version 2.4 fixed an uninitialized line number bug, released in May 2012. -% Version 2.5 development was started in Aug 2012; released in Feb 2013. -% better tracing of font definitions, reported by -% Bruno Le Floch <blflatex@@gmail.com>, Jul 2012. -% Version 2.6 development was started in Mar 2013; released in ??? 201?. -% enable hyphenation of text between \beginL and \endL or -% between \beginR and \endR, problem reported by -% Vafa Khalighi <vafalgk@@gmail.com>, Nov 2013. -% better handling of right-to-left text -- to be done. - -% Although considerable effort has been expended to make the e-TeX program -% correct and reliable, no warranty is implied; the author disclaims any -% obligation or liability for damages, including but not limited to -% special, indirect, or consequential damages arising out of or in -% connection with the use or performance of this software. This work has -% been a ``labor of love'' and the author hopes that users enjoy it. - -% Here is TeX material that gets inserted after \input webmac -\def\hang{\hangindent 3em\noindent\ignorespaces} -\def\hangg#1 {\hang\hbox{#1 }} -\def\textindent#1{\hangindent2.5em\noindent\hbox to2.5em{\hss#1 }\ignorespaces} -\font\ninerm=cmr9 -\let\mc=\ninerm % medium caps for names like SAIL -\def\eTeX{$\varepsilon$-\TeX} -\font\revrm=xbmc10 % for right-to-left text -% to generate xbmc10 (i.e., reflected cmbx10) use a file -% xbmc10.mf containing: -%+++++++++++++++++++++++++++++++++++++++++++++++++ -% if unknown cmbase: input cmbase fi -% extra_endchar := extra_endchar & -% "currentpicture:=currentpicture " & -% "reflectedabout((.5[l,r],0),(.5[l,r],1));"; -% input cmbx10 -%+++++++++++++++++++++++++++++++++++++++++++++++++ -\ifx\beginL\undefined % this is TeX - \def\XeT{X\kern-.125em\lower.5ex\hbox{E}\kern-.1667emT} - \def\TeXeT{\TeX-\hbox{\revrm \XeT}} % for TeX-XeT - \def\TeXXeT{\TeX-\hbox{\revrm -\XeT}} % for TeX--XeT -\else - \ifx\eTeXversion\undefined % this is \TeXeT - \def\TeXeT{\TeX-{\revrm\beginR\TeX\endR}} % for TeX-XeT - \def\TeXXeT{\TeX-{\revrm\beginR\TeX-\endR}} % for TeX--XeT - \else % this is \eTeX - \def\TeXeT{\TeX-{\TeXXeTstate=1\revrm\beginR\TeX\endR}} % for TeX-XeT - \def\TeXXeT{\TeX-{\TeXXeTstate=1\revrm\beginR\TeX-\endR}} % for TeX--XeT - \fi -\fi -\def\PASCAL{Pascal} -\def\ph{\hbox{Pascal-H}} -\def\pct!{{\char`\%}} % percent sign in ordinary text -\def\grp{\.{\char'173...\char'175}} -\font\logo=logo10 % font used for the METAFONT logo -\def\MF{{\logo META}\-{\logo FONT}} -\def\<#1>{$\langle#1\rangle$} -\def\section{\mathhexbox278} - -\def\(#1){} % this is used to make section names sort themselves better -\def\9#1{} % this is used for sort keys in the index via @@:sort key}{entry@@> - -\let\@@=\relax % we want to be able to \write a \? - -\def\title{k\TeX} -% system dependent redefinitions of \title should come later -% and should use: -% \toks0=\expandafter{\title} -% \edef\title{...\the\toks0...} -\let\maybe=\iffalse % print only changed modules -\def\topofcontents{\hsize 5.5in - \vglue 0pt plus 1fil minus 1.5in - \def\@@##1]{\hbox to 1in{\hfil##1.\ }} - } -\def\botofcontents{\vskip 0pt plus 1fil minus 1.5in} -\pageno=3 -\def\glob{13} % this should be the section number of "<Global...>" -\def\gglob{20, 26} % this should be the next two sections of "<Global...>" - -\def\.#1{\leavevmode\hbox{\tentex % typewriter type for strings - \let\\=\BS % backslash in a string - \let\'=\RQ % right quote in a string - \let\`=\LQ % left quote in a string - \let\{=\LB % left brace in a string - \let\}=\RB % right brace in a string - \let\~=\TL % tilde in a string - \let\ =\SP % space in a string - \let\_=\UL % underline in a string - \let\&=\AM % ampersand in a string - #1\kern.05em}} -\def\^{\ifmmode\mathchar"222 \else\char`^ \fi} % pointer or hat -\def\LQ{{\tt\char'22}} % left quote in a string -\def\RQ{{\tt\char'23}} % right quote in a string -\def\dotdot{\mathrel{.\,.}} % double dot, used only in math mode -@s dotdot TeX -@* Introduction. -This is \eTeX, a program derived from and extending the capabilities of -\TeX, a document compiler intended to produce typesetting of high -quality. -The \PASCAL\ program that follows is the definition of \TeX82, a standard -@:PASCAL}{\PASCAL@> -@!@:TeX82}{\TeX82@> -version of \TeX\ that is designed to be highly portable so that identical output -will be obtainable on a great variety of computers. - -The main purpose of the following program is to explain the algorithms of \TeX\ -as clearly as possible. As a result, the program will not necessarily be very -efficient when a particular \PASCAL\ compiler has translated it into a -particular machine language. However, the program has been written so that it -can be tuned to run efficiently in a wide variety of operating environments -by making comparatively few changes. Such flexibility is possible because -the documentation that follows is written in the \.{WEB} language, which is -at a higher level than \PASCAL; the preprocessing step that converts \.{WEB} -to \PASCAL\ is able to introduce most of the necessary refinements. -Semi-automatic translation to other languages is also feasible, because the -program below does not make extensive use of features that are peculiar to -\PASCAL. - -A large piece of software like \TeX\ has inherent complexity that cannot -be reduced below a certain level of difficulty, although each individual -part is fairly simple by itself. The \.{WEB} language is intended to make -the algorithms as readable as possible, by reflecting the way the -individual program pieces fit together and by providing the -cross-references that connect different parts. Detailed comments about -what is going on, and about why things were done in certain ways, have -been liberally sprinkled throughout the program. These comments explain -features of the implementation, but they rarely attempt to explain the -\TeX\ language itself, since the reader is supposed to be familiar with -{\sl The \TeX book}. -@.WEB@> -@:TeXbook}{\sl The \TeX book@> - -@ The present implementation has a long ancestry, beginning in the summer -of~1977, when Michael~F. Plass and Frank~M. Liang designed and coded -a prototype -@^Plass, Michael Frederick@> -@^Liang, Franklin Mark@> -@^Knuth, Donald Ervin@> -based on some specifications that the author had made in May of that year. -This original proto\TeX\ included macro definitions and elementary -manipulations on boxes and glue, but it did not have line-breaking, -page-breaking, mathematical formulas, alignment routines, error recovery, -or the present semantic nest; furthermore, -it used character lists instead of token lists, so that a control sequence -like \.{\\halign} was represented by a list of seven characters. A -complete version of \TeX\ was designed and coded by the author in late -1977 and early 1978; that program, like its prototype, was written in the -{\mc SAIL} language, for which an excellent debugging system was -available. Preliminary plans to convert the {\mc SAIL} code into a form -somewhat like the present ``web'' were developed by Luis Trabb~Pardo and -@^Trabb Pardo, Luis Isidoro@> -the author at the beginning of 1979, and a complete implementation was -created by Ignacio~A. Zabala in 1979 and 1980. The \TeX82 program, which -@^Zabala Salelles, Ignacio Andr\'es@> -was written by the author during the latter part of 1981 and the early -part of 1982, also incorporates ideas from the 1979 implementation of -@^Guibas, Leonidas Ioannis@> -@^Sedgewick, Robert@> -@^Wyatt, Douglas Kirk@> -\TeX\ in {\mc MESA} that was written by Leonidas Guibas, Robert Sedgewick, -and Douglas Wyatt at the Xerox Palo Alto Research Center. Several hundred -refinements were introduced into \TeX82 based on the experiences gained with -the original implementations, so that essentially every part of the system -has been substantially improved. After the appearance of ``Version 0'' in -September 1982, this program benefited greatly from the comments of -many other people, notably David~R. Fuchs and Howard~W. Trickey. -A final revision in September 1989 extended the input character set to -eight-bit codes and introduced the ability to hyphenate words from -different languages, based on some ideas of Michael~J. Ferguson. -@^Fuchs, David Raymond@> -@^Trickey, Howard Wellington@> -@^Ferguson, Michael John@> - -No doubt there still is plenty of room for improvement, but the author -is firmly committed to keeping \TeX82 ``frozen'' from now on; stability -and reliability are to be its main virtues. - -On the other hand, the \.{WEB} description can be extended without changing -the core of \TeX82 itself, and the program has been designed so that such -extensions are not extremely difficult to make. -The |banner| string defined here should be changed whenever \TeX\ -undergoes any modifications, so that it will be clear which version of -\TeX\ might be the guilty party when a problem arises. -@^extensions to \TeX@> -@^system dependencies@> - -This program contains code for various features extending \TeX, -therefore this program is called `\eTeX' and not -`\TeX'; the official name `\TeX' by itself is reserved -for software systems that are fully compatible with each other. -A special test suite called the ``\.{TRIP} test'' is available for -helping to determine whether a particular implementation deserves to be -known as `\TeX' [cf.~Stanford Computer Science report CS1027, -November 1984]. - -A similar test suite called the ``\.{e-TRIP} test'' is available for -helping to determine whether a particular implementation deserves to be -known as `\eTeX'. - -@d eTeX_version 2 /* \.{\\eTeXversion} */ -@d eTeX_revision ".6" /* \.{\\eTeXrevision} */ -@d eTeX_version_string "-2.6" /*current \eTeX\ version*/ -@# -@d eTeX_banner "This is e-TeX, Version 3.141592653" eTeX_version_string " (HINT)" - /*printed when \eTeX\ starts*/ -@# -@d TeX_banner "This is TeX, Version 3.141592653 (HINT)" /*printed when \TeX\ starts*/ -@# -@d banner "This is HiTeX, Version 3.141592653" eTeX_version_string /*printed when \TeX\ starts*/ -@# -@d TEX ETEX /*change program name into |ETEX|*/ -@# -@d eTeX_states 1 /*number of \eTeX\ state variables in |eqtb|*/ - -@ Different \PASCAL s have slightly different conventions, and the present -@!@:PASCAL H}{\ph@> -program expresses \TeX\ in terms of the \PASCAL\ that was -available to the author in 1982. Constructions that apply to -this particular compiler, which we shall call \ph, should help the -reader see how to make an appropriate interface for other systems -if necessary. (\ph\ is Charles Hedrick's modification of a compiler -@^Hedrick, Charles Locke@> -for the DECsystem-10 that was originally developed at the University of -Hamburg; cf.\ {\sl Software---Practice and Experience \bf6} (1976), -29--42. The \TeX\ program below is intended to be adaptable, without -extensive changes, to most other versions of \PASCAL, so it does not fully -use the admirable features of \ph. Indeed, a conscious effort has been -made here to avoid using several idiosyncratic features of standard -\PASCAL\ itself, so that most of the code can be translated mechanically -into other high-level languages. For example, the `\&{with}' and `\\{new}' -features are not used, nor are pointer types, set types, or enumerated -scalar types; there are no `\&{var}' parameters, except in the case of files ---- \eTeX, however, does use `\&{var}' parameters for the |reverse| function; -there are no tag fields on variant records; there are no assignments -|double=int|; no procedures are declared local to other procedures.) - -The portions of this program that involve system-dependent code, where -changes might be necessary because of differences between \PASCAL\ compilers -and/or differences between -operating systems, can be identified by looking at the sections whose -numbers are listed under `system dependencies' in the index. Furthermore, -the index entries for `dirty \PASCAL' list all places where the restrictions -of \PASCAL\ have not been followed perfectly, for one reason or another. -@!@^system dependencies@> -@!@^dirty \PASCAL@> - -Incidentally, \PASCAL's standard |round| function can be problematical, -because it disagrees with the IEEE floating-point standard. -Many implementors have -therefore chosen to substitute their own home-grown rounding procedure. - -@ The following is an outline of the program, whose -components will be filled in later, using the conventions of \.{WEB}. -@.WEB@> -For example, the portion of the program called `\X\glob:Global -variables\X' below will be replaced by a sequence of variable declarations -that starts in $\section\glob$ of this documentation. In this way, we are able -to define each individual global variable when we are prepared to -understand what it means; we do not have to define all of the globals at -once. Cross references in $\section\glob$, where it says ``See also -sections \gglob, \dots,'' also make it possible to look at the set of -all global variables, if desired. Similar remarks apply to the other -portions of the program. - -@p @<Header files and function declarations@>@; -#include "htex.h" -#include "hitex.h" -@<Global variables@>@; -@# - -static void initialize(void) /*this procedure gets things started properly*/ - {@+@<Local variables for initialization@>@; - @<Initialize whatever \TeX\ might access@>; - } @# -@<Basic printing procedures@>@; -@<Error handling procedures@>@; - -@ The overall \TeX\ program begins with the heading just shown, after which -comes a bunch of procedure declarations and function declarations. -Finally we will get to the main program, which begins with the -comment `|start_here|'. If you want to skip down to the -main program now, you can look up `|start_here|' in the index. -But the author suggests that the best way to understand this program -is to follow pretty much the order of \TeX's components as they appear in the -\.{WEB} description you are now reading, since the present ordering is -intended to combine the advantages of the ``bottom up'' and ``top down'' -approaches to the problem of understanding a somewhat complicated system. - -@ There is no need to declare labels in \CEE/, but occasionally -it is necessary to insert header files and declare functions -very early in the program. For example, the function |s_no| -which uses |make_string| to convert a \CEE/ string into -a string number is used in |initialize| and needs a forward -declaration. - -@<Header files and function declarations@>= -extern int s_no(const char *str); - -@ Some of the code below is intended to be used only when diagnosing the -strange behavior that sometimes occurs when \TeX\ is being installed or -when system wizards are fooling around with \TeX\ without quite knowing -what they are doing. Such code will not normally be compiled; it is -delimited by the codewords `$|debug|\ldots|debug|$', with apologies -to people who wish to preserve the purity of English. - -Similarly, there is some conditional code delimited by -`$|stat|\ldots|tats|$' that is intended for use when statistics are to be -kept about \TeX's memory usage. The |stat| $\ldots$ |tats| code also -implements diagnostic information for \.{\\tracingparagraphs}, -\.{\\tracingpages}, and \.{\\tracingrestores}. -@^debugging@> - -@ This program has two important variations: (1) There is a long and slow -version called \.{INITEX}, which does the extra calculations needed to -@.INITEX@> -initialize \TeX's internal tables; and (2)~there is a shorter and faster -production version, which cuts the initialization to a bare minimum. -Parts of the program that are needed in (1) but not in (2) are delimited by -|#ifdef| |INIT|\dots\ |#endif|. - -\TeX\ Live has established the common practice -to select the initialization code at runtime -using the |iniversion| variable. - -@<Initialize whatever...@>= -@<Set initial values of key variables@>@/ -#ifdef @!INIT -if (iniversion) {@+@<Initialize table entries (done by \.{INITEX} only)@>@;@+} -#endif - -@ Most of the external declarations needed are included using standard -header files. - -@s uint8_t int -@s int16_t int -@s uint16_t int -@s int32_t int -@s uint32_t int -@s halfword int -@s in TeX -@s line normal -@s to do - -@<Header files and function declarations@>= -#include <stdint.h> -#include <stdbool.h> -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <math.h> - -@ Further it is necessary to define some build in primitives of -\PASCAL\ that are otherwise not available in \CEE/. -@:PASCAL H}{\ph@> - -@d odd(X) ((X)&1) -@d chr(X) ((unsigned char)(X)) -@d ord(X) ((unsigned int)(X)) -@d abs(X) ((X)>-(X)?(X):-(X)) -@d round(X) ((int)((X)>=0.0?floor((X)+0.5):ceil((X)-0.5))) - -@ The following parameters can be changed at compile time to extend or -reduce \TeX's capacity. They may have different values in \.{INITEX} and -in production versions of \TeX. -@.INITEX@> -@^system dependencies@> - -@<Constants...@>= -@!mem_max=5000000, /*greatest index in \TeX's internal |mem| array; - must be strictly less than |max_halfword|; - must be equal to |mem_top| in \.{INITEX}, otherwise | >= mem_top|*/ -@!mem_min=0, /*smallest index in \TeX's internal |mem| array; - must be |min_halfword| or more; - must be equal to |mem_bot| in \.{INITEX}, otherwise | <= mem_bot|*/ -@!buf_size=2000000, /*maximum number of characters simultaneously present in - current lines of open files and in control sequences between - \.{\\csname} and \.{\\endcsname}; must not exceed |max_halfword|*/ -@!error_line=79, /*width of context lines on terminal error messages*/ -@!half_error_line=50, /*width of first lines of contexts in terminal - error messages; should be between 30 and |error_line-15|*/ -@!max_print_line=79, /*width of longest text lines output; should be at least 60*/ -@!stack_size=5000, /*maximum number of simultaneous input sources*/ -@!max_in_open=15, /*maximum number of input files and error insertions that - can be going on simultaneously*/ -@!font_max=255, /*maximum internal font number; must not exceed |max_quarterword| - and must be at most |font_base+256|*/ -@!font_mem_size=8000000, /*number of words of |font_info| for all fonts*/ -@!param_size=10000, /*maximum number of simultaneous macro parameters*/ -@!nest_size=500, /*maximum number of semantic levels simultaneously active*/ -@!max_strings=500000, /*maximum number of strings; must not exceed |max_halfword|*/ -@!string_vacancies=90000, /*the minimum number of characters that should be - available for the user's control sequences and font names, - after \TeX's own error messages are stored*/ -@!pool_size=6250000, /*maximum number of characters in strings, including all - error messages and help texts, and the names of all fonts and - control sequences; must exceed |string_vacancies| by the total - length of \TeX's own strings, which is currently about 23000*/ -@!save_size=100000, /*space for saving values outside of current group; must be - at most |max_halfword|*/ -@!trie_size=1000000, /*space for hyphenation patterns; should be larger for - \.{INITEX} than it is in production versions of \TeX*/ -@!trie_op_size=35111, /*space for ``opcodes'' in the hyphenation patterns*/ -@!dvi_buf_size=16384, /*size of the output buffer; must be a multiple of 8*/ -@!file_name_size=1024, /*file names shouldn't be longer than this*/ -@!empty_string=256 /*the empty string follows after 256 characters*/ - -@ Like the preceding parameters, the following quantities can be changed -at compile time to extend or reduce \TeX's capacity. But if they are changed, -it is necessary to rerun the initialization program \.{INITEX} -@.INITEX@> -to generate new tables for the production \TeX\ program. -One can't simply make helter-skelter changes to the following constants, -since certain rather complex initialization -numbers are computed from them. They are defined here using -\.{WEB} macros, instead of being put into \PASCAL's |const| list, in order to -emphasize this distinction. - -@d mem_bot 0 /*smallest index in the |mem| array dumped by \.{INITEX}; - must not be less than |mem_min|*/ -@d mem_top 5000000 /*largest index in the |mem| array dumped by \.{INITEX}; - must be substantially larger than |mem_bot| - and not greater than |mem_max|*/ -@d font_base 0 /*smallest internal font number; must not be less - than |min_quarterword|*/ -@d hash_size 15000 /*maximum number of control sequences; it should be at most - about |(mem_max-mem_min)/(double)10|*/ -@d hash_prime 12757 /*a prime number equal to about 85\pct! of |hash_size|*/ -@d hyph_size 8191 /*another prime; the number of \.{\\hyphenation} exceptions*/ -@^system dependencies@> - -@ In case somebody has inadvertently made bad settings of the ``constants,'' -\TeX\ checks them using a global variable called |bad|. - -This is the first of many sections of \TeX\ where global variables are -defined. - -@<Glob...@>= -static int @!bad; /*is some ``constant'' wrong?*/ - -@ Later on we will say `\ignorespaces|if (mem_max >= max_halfword) bad=14|', -or something similar. (We can't do that until |max_halfword| has been defined.) - -@<Check the ``constant'' values for consistency@>= -bad=0; -if ((half_error_line < 30)||(half_error_line > error_line-15)) bad=1; -if (max_print_line < 60) bad=2; -if (dvi_buf_size%8!=0) bad=3; -if (mem_bot+1100 > mem_top) bad=4; -if (hash_prime > hash_size) bad=5; -if (max_in_open >= 128) bad=6; -if (mem_top < 256+11) bad=7; /*we will want |null_list > 255|*/ - -@ Labels are given symbolic names by the following definitions, so that -occasional |goto| statements will be meaningful. We insert the label -`|end|' just before the `\ignorespaces|} |\unskip' of a procedure in -which we have used the `|goto end|' statement defined below; the label -`|restart|' is occasionally used at the very beginning of a procedure; and -the label `|reswitch|' is occasionally used just prior to a |case| -statement in which some cases change the conditions and we wish to branch -to the newly applicable case. Loops that are set up with the |loop| -construction defined below are commonly exited by going to `|done|' or to -`|found|' or to `|not_found|', and they are sometimes repeated by going to -`|resume|'. If two or more parts of a subroutine start differently but -end up the same, the shared code may be gathered together at -`|common_ending|'. - -Incidentally, this program never declares a label that isn't actually used, -because some fussy \PASCAL\ compilers will complain about redundant labels. - -@ Here are some macros for common programming idioms. - -@d incr(A) A=A+1 /*increase a variable by unity*/ -@d decr(A) A=A-1 /*decrease a variable by unity*/ -@d negate(A) A=-A /*change the sign of a variable*/ -@d loop @+while (true) @+ /*repeat over and over until a |goto| happens*/ -@f loop else - /*\.{WEB}'s |else| acts like `\ignorespaces|while true do|\unskip'*/ -@d do_nothing /*empty statement*/ -@d empty 0 /*symbolic name for a null constant*/ - -@* The character set. -In order to make \TeX\ readily portable to a wide variety of -computers, all of its input text is converted to an internal eight-bit -code that includes standard ASCII, the ``American Standard Code for -Information Interchange.'' This conversion is done immediately when each -character is read in. Conversely, characters are converted from ASCII to -the user's external representation just before they are output to a -text file. - -Such an internal code is relevant to users of \TeX\ primarily because it -governs the positions of characters in the fonts. For example, the -character `\.A' has ASCII code $65=0101$, and when \TeX\ typesets -this letter it specifies character number 65 in the current font. -If that font actually has `\.A' in a different position, \TeX\ doesn't -know what the real position is; the program that does the actual printing from -\TeX's device-independent files is responsible for converting from ASCII to -a particular font encoding. -@^ASCII code@> - -\TeX's internal code also defines the value of constants -that begin with a reverse apostrophe; and it provides an index to the -\.{\\catcode}, \.{\\mathcode}, \.{\\uccode}, \.{\\lccode}, and \.{\\delcode} -tables. - -@ Characters of text that have been converted to \TeX's internal form -are said to be of type |ASCII_code|, which is a subrange of the integers. - -@<Types...@>= -typedef uint8_t ASCII_code; /*eight-bit numbers*/ - -@ The original \PASCAL\ compiler was designed in the late 60s, when six-bit -character sets were common, so it did not make provision for lowercase -letters. Nowadays, of course, we need to deal with both capital and small -letters in a convenient way, especially in a program for typesetting; -so the present specification of \TeX\ has been written under the assumption -that the \PASCAL\ compiler and run-time system permit the use of text files -with more than 64 distinguishable characters. More precisely, we assume that -the character set contains at least the letters and symbols associated -with ASCII codes 040 through 0176; all of these characters are now -available on most computer terminals. - -Since we are dealing with more characters than were present in the first -\PASCAL\ compilers, we have to decide what to call the associated data -type. Some \PASCAL s use the original name |unsigned char| for the -characters in text files, even though there now are more than 64 such -characters, while other \PASCAL s consider |unsigned char| to be a 64-element -subrange of a larger data type that has some other name. - -In order to accommodate this difference, we shall use the name |text_char| -to stand for the data type of the characters that are converted to and -from |ASCII_code| when they are input and output. We shall also assume -that |text_char| consists of the elements |chr(first_text_char)| through -|chr(last_text_char)|, inclusive. The following definitions should be -adjusted if necessary. -@^system dependencies@> - -@s text_char char -@d text_char unsigned char /*the data type of characters in text files*/ -@d first_text_char 0 /*ordinal number of the smallest element of |text_char|*/ -@d last_text_char 255 /*ordinal number of the largest element of |text_char|*/ - -@<Local variables for init...@>= -int @!i; - -@ The \TeX\ processor converts between ASCII code and -the user's external character set by means of arrays |xord| and |xchr| -that are analogous to \PASCAL's |ord| and |chr| functions. - -@<Glob...@>= -static ASCII_code @!xord[256]; - /*specifies conversion of input characters*/ -static text_char @!xchr[256]; - /*specifies conversion of output characters*/ - -@ Since we are assuming that our \PASCAL\ system is able to read and -write the visible characters of standard ASCII (although not -necessarily using the ASCII codes to represent them), the following -assignment statements initialize the standard part of the |xchr| array -properly, without needing any system-dependent changes. On the other -hand, it is possible to implement \TeX\ with less complete character -sets, and in such cases it will be necessary to change something here. -@^system dependencies@> - -@<Set init...@>= -xchr[040]=' '; -xchr[041]='!'; -xchr[042]='"'; -xchr[043]='#'; -xchr[044]='$'; -xchr[045]='%'; -xchr[046]='&'; -xchr[047]='\'';@/ -xchr[050]='('; -xchr[051]=')'; -xchr[052]='*'; -xchr[053]='+'; -xchr[054]=','; -xchr[055]='-'; -xchr[056]='.'; -xchr[057]='/';@/ -xchr[060]='0'; -xchr[061]='1'; -xchr[062]='2'; -xchr[063]='3'; -xchr[064]='4'; -xchr[065]='5'; -xchr[066]='6'; -xchr[067]='7';@/ -xchr[070]='8'; -xchr[071]='9'; -xchr[072]=':'; -xchr[073]=';'; -xchr[074]='<'; -xchr[075]='='; -xchr[076]='>'; -xchr[077]='?';@/ -xchr[0100]='@@'; -xchr[0101]='A'; -xchr[0102]='B'; -xchr[0103]='C'; -xchr[0104]='D'; -xchr[0105]='E'; -xchr[0106]='F'; -xchr[0107]='G';@/ -xchr[0110]='H'; -xchr[0111]='I'; -xchr[0112]='J'; -xchr[0113]='K'; -xchr[0114]='L'; -xchr[0115]='M'; -xchr[0116]='N'; -xchr[0117]='O';@/ -xchr[0120]='P'; -xchr[0121]='Q'; -xchr[0122]='R'; -xchr[0123]='S'; -xchr[0124]='T'; -xchr[0125]='U'; -xchr[0126]='V'; -xchr[0127]='W';@/ -xchr[0130]='X'; -xchr[0131]='Y'; -xchr[0132]='Z'; -xchr[0133]='['; -xchr[0134]='\\'; -xchr[0135]=']'; -xchr[0136]='^'; -xchr[0137]='_';@/ -xchr[0140]='`'; -xchr[0141]='a'; -xchr[0142]='b'; -xchr[0143]='c'; -xchr[0144]='d'; -xchr[0145]='e'; -xchr[0146]='f'; -xchr[0147]='g';@/ -xchr[0150]='h'; -xchr[0151]='i'; -xchr[0152]='j'; -xchr[0153]='k'; -xchr[0154]='l'; -xchr[0155]='m'; -xchr[0156]='n'; -xchr[0157]='o';@/ -xchr[0160]='p'; -xchr[0161]='q'; -xchr[0162]='r'; -xchr[0163]='s'; -xchr[0164]='t'; -xchr[0165]='u'; -xchr[0166]='v'; -xchr[0167]='w';@/ -xchr[0170]='x'; -xchr[0171]='y'; -xchr[0172]='z'; -xchr[0173]='{'; -xchr[0174]='|'; -xchr[0175]='}'; -xchr[0176]='~';@/ - -@ Some of the ASCII codes without visible characters have been given symbolic -names in this program because they are used with a special meaning. - -@d null_code 00 /*ASCII code that might disappear*/ -@d carriage_return 015 /*ASCII code used at end of line*/ -@d invalid_code 0177 /*ASCII code that many systems prohibit in text files*/ - -@ The ASCII code is ``standard'' only to a certain extent, since many -computer installations have found it advantageous to have ready access -to more than 94 printing characters. Appendix~C of {\sl The \TeX book\/} -gives a complete specification of the intended correspondence between -characters and \TeX's internal representation. -@:TeXbook}{\sl The \TeX book@> - -If \TeX\ is being used -on a garden-variety \PASCAL\ for which only standard ASCII -codes will appear in the input and output files, it doesn't really matter -what codes are specified in |xchr[0 dotdot 037]|, but the safest policy is to -blank everything out by using the code shown below. - -However, other settings of |xchr| will make \TeX\ more friendly on -computers that have an extended character set, so that users can type things -like `\.^^Z' instead of `\.{\\ne}'. People with extended character sets can -assign codes arbitrarily, giving an |xchr| equivalent to whatever -characters the users of \TeX\ are allowed to have in their input files. -It is best to make the codes correspond to the intended interpretations as -shown in Appendix~C whenever possible; but this is not necessary. For -example, in countries with an alphabet of more than 26 letters, it is -usually best to map the additional letters into codes less than~040. -To get the most ``permissive'' character set, change |' '| on the -right of these assignment statements to |chr(i)|. -@^character set dependencies@> -@^system dependencies@> - -@<Set init...@>= -for (i=0; i<=037; i++) xchr[i]=chr(i); /* k\TeX\ */ -for (i=0177; i<=0377; i++) xchr[i]=chr(i); /* k\TeX\ */ - -@ The following system-independent code makes the |xord| array contain a -suitable inverse to the information in |xchr|. Note that if |xchr[i]==xchr[j]| -where |i < j < 0177|, the value of |xord[xchr[i]]| will turn out to be -|j| or more; hence, standard ASCII code numbers will be used instead of -codes below 040 in case there is a coincidence. - -@<Set init...@>= -for (i=first_text_char; i<=last_text_char; i++) xord[chr(i)]=invalid_code; -for (i=0200; i<=0377; i++) xord[xchr[i]]=i; -for (i=0; i<=0176; i++) xord[xchr[i]]=i; - -@* Input and output. -The bane of portability is the fact that different operating systems treat -input and output quite differently, perhaps because computer scientists -have not given sufficient attention to this problem. People have felt somehow -that input and output are not part of ``real'' programming. Well, it is true -that some kinds of programming are more fun than others. With existing -input/output conventions being so diverse and so messy, the only sources of -joy in such parts of the code are the rare occasions when one can find a -way to make the program a little less bad than it might have been. We have -two choices, either to attack I/O now and get it over with, or to postpone -I/O until near the end. Neither prospect is very attractive, so let's -get it over with. - -The basic operations we need to do are (1)~inputting and outputting of -text, to or from a file or the user's terminal; (2)~inputting and -outputting of eight-bit bytes, to or from a file; (3)~instructing the -operating system to initiate (``open'') or to terminate (``close'') input or -output from a specified file; (4)~testing whether the end of an input -file has been reached. - -\TeX\ needs to deal with two kinds of files. -We shall use the term |alpha_file| for a file that contains textual data, -and the term |byte_file| for a file that contains eight-bit binary information. -These two types turn out to be the same on many computers, but -sometimes there is a significant distinction, so we shall be careful to -distinguish between them. Standard protocols for transferring -such files from computer to computer, via high-speed networks, are -now becoming available to more and more communities of users. - -The program actually makes use also of a third kind of file, called a -|word_file|, when dumping and reloading base information for its own -initialization. We shall define a word file later; but it will be possible -for us to specify simple operations on word files before they are defined. - -@<Types...@>= -typedef uint8_t eight_bits; /*unsigned one-byte quantity*/ -typedef struct {@+FILE *f;@+text_char@,d;@+} alpha_file; /*files that contain textual data*/ -typedef struct {@+FILE *f;@+eight_bits@,d;@+} byte_file; /*files that contain binary data*/ - -@ Most of what we need to do with respect to input and output can be handled -by the I/O facilities that are standard in \PASCAL, i.e., the routines -called |get|, |put|, |eof|, and so on. But -standard \PASCAL\ does not allow file variables to be associated with file -names that are determined at run time, so it cannot be used to implement -\TeX; some sort of extension to \PASCAL's ordinary |reset| and |rewrite| -is crucial for our purposes. We shall assume that |name_of_file| is a variable -of an appropriate type such that the \PASCAL\ run-time system being used to -implement \TeX\ can open a file whose external name is specified by -|name_of_file|. -@^system dependencies@> - -@<Glob...@>= -unsigned char @!name_of_file0[file_name_size+1]={0}, *const @!name_of_file = @!name_of_file0-1;@;@/ - /*on some systems this may be a \&{record} variable*/ -int @!name_length;@/ /*this many characters are actually - relevant in |name_of_file| (the rest are blank)*/ - -@ k\TeX\ uses the {\tt kpathsearch} library to implement access to files. -To do so we declare \TeX's functions here and postpone the -actual implementations. These functions do not to issue their own -error messages if something goes wrong. If a file identified by -|name_of_file| cannot be found, -or if such a file cannot be opened for some other reason -(e.g., someone may already be trying to write the same file) -\TeX's file-opening procedures return |false|. -This allows \TeX\ to undertake appropriate corrective action. -@^system dependencies@> - -@p static bool a_open_in(alpha_file *f); /*open a text file for input*/ -static bool a_open_out(alpha_file *f); /*open a text file for output*/ -static bool b_open_in(byte_file *f); /*open a binary file for input*/ -static bool b_open_out(byte_file *f); /*open a binary file for output*/ -static bool w_open_in(word_file *f); /*open a word file for input*/ -#ifdef @!INIT -static bool w_open_out(word_file *f); /*open a word file for output*/ -#endif - -@ Files can be closed with the \ph\ routine `|pascal_close(f)|', which -@:PASCAL H}{\ph@> -@^system dependencies@> -should be used when all input or output with respect to |f| has been completed. -This makes |f| available to be opened again, if desired; and if |f| was used for -output, the |pascal_close| operation makes the corresponding external file appear -on the user's area, ready to be read. - -These procedures should not generate error messages if a file is -being closed before it has been successfully opened. - -@p static void a_close(alpha_file *f) /*close a text file*/ -{@+pascal_close((*f)); -} -@# -static void b_close(byte_file *f) /*close a binary file*/ -{@+pascal_close((*f)); -} -@# -static void w_close(word_file *f) /*close a word file*/ -{@+pascal_close((*f)); -} - -@ Binary input and output are done with \PASCAL's ordinary |get| and |put| -procedures, so we don't have to make any other special arrangements for -binary~I/O. Text output is also easy to do with standard \PASCAL\ routines. -The treatment of text input is more difficult, however, because -of the necessary translation to |ASCII_code| values. -\TeX's conventions should be efficient, and they should -blend nicely with the user's operating environment. - -@ Input from text files is read one line at a time, using a routine called -|input_ln|. This function is defined in terms of global variables called -|buffer|, |first|, and |last| that will be described in detail later; for -now, it suffices for us to know that |buffer| is an array of |ASCII_code| -values, and that |first| and |last| are indices into this array -representing the beginning and ending of a line of text. - -@<Glob...@>= -static ASCII_code @!buffer[buf_size+1]; /*lines of characters being read*/ -static int @!first; /*the first unused position in |buffer|*/ -static int @!last; /*end of the line just input to |buffer|*/ -static int @!max_buf_stack; /*largest index used in |buffer|*/ - -@ The |input_ln| function brings the next line of input from the specified -file into available positions of the buffer array and returns the value -|true|, unless the file has already been entirely read, in which case it -returns |false| and sets |last=first|. In general, the |ASCII_code| -numbers that represent the next line of the file are input into -|buffer[first]|, |buffer[first+1]|, \dots, |buffer[last-1]|; and the -global variable |last| is set equal to |first| plus the length of the -line. Trailing blanks are removed from the line; thus, either |last==first| -(in which case the line was entirely blank) or |buffer[last-1]!=' '|. - -An overflow error is given, however, if the normal actions of |input_ln| -would make |last >= buf_size|; this is done so that other parts of \TeX\ -can safely look at the contents of |buffer[last+1]| without overstepping -the bounds of the |buffer| array. Upon entry to |input_ln|, the condition -|first < buf_size| will always hold, so that there is always room for an -``empty'' line. - -The variable |max_buf_stack|, which is used to keep track of how large -the |buf_size| parameter must be to accommodate the present job, is -also kept up to date by |input_ln|. - -If the |bypass_eoln| parameter is |true|, |input_ln| will do a |get| -before looking at the first character of the line; this skips over -an |eoln| that was in |f.d|. The procedure does not do a |get| when it -reaches the end of the line; therefore it can be used to acquire input -from the user's terminal as well as from ordinary text files. - -Standard \PASCAL\ says that a file should have |eoln| immediately -before |eof|, but \TeX\ needs only a weaker restriction: If |eof| -occurs in the middle of a line, the system function |eoln| should return -a |true| result (even though |f.d| will be undefined). - -Since the inner loop of |input_ln| is part of \TeX's ``inner loop''---each -character of input comes in at this place---it is wise to reduce system -overhead by making use of special routines that read in an entire array -of characters at once, if such routines are available. The following -code uses standard \PASCAL\ to illustrate what needs to be done, but -finer tuning is often possible at well-developed \PASCAL\ sites. -@^inner loop@> - -@p static bool input_ln(alpha_file *f, bool @!bypass_eoln) - /*inputs the next line or returns |false|*/ -{@+int last_nonblank; /*|last| with trailing blanks removed*/ -if (bypass_eoln) if (!eof((*f))) get((*f)); - /*input the first character of the line into |f.d|*/ -last=first; /*cf.\ Matthew 19\thinspace:\thinspace30*/ -if (eof((*f))) return false; -else{@+last_nonblank=first; - while (!eoln((*f))) - {@+if (last >= max_buf_stack) - {@+max_buf_stack=last+1; - if (max_buf_stack==buf_size) - @<Report overflow of the input buffer, and abort@>; - } - buffer[last]=xord[(*f).d];get((*f));incr(last); - if (buffer[last-1]!=' ') last_nonblank=last; - } - last=last_nonblank;return true; - } -} - -@ The user's terminal acts essentially like other files of text, except -that it is used both for input and for output. When the terminal is -considered an input file, the file variable is called |term_in|, and when it -is considered an output file the file variable is |term_out|. -@^system dependencies@> - -@<Glob...@>= -static alpha_file @!term_in; /*the terminal as an input file*/ -static alpha_file @!term_out; /*the terminal as an output file*/ - -@ Here is how to open the terminal files -in \ph. The `\.{/I}' switch suppresses the first |get|. -@:PASCAL H}{\ph@> -@^system dependencies@> - -@d t_open_in term_in.f=stdin /*open the terminal for text input*/ -@d t_open_out term_out.f=stdout /*open the terminal for text output*/ - -@ Sometimes it is necessary to synchronize the input/output mixture that -happens on the user's terminal, and three system-dependent -procedures are used for this -purpose. The first of these, |update_terminal|, is called when we want -to make sure that everything we have output to the terminal so far has -actually left the computer's internal buffers and been sent. -The second, |clear_terminal|, is called when we wish to cancel any -input that the user may have typed ahead (since we are about to -issue an unexpected error message). The third, |wake_up_terminal|, -is supposed to revive the terminal if the user has disabled it by -some instruction to the operating system. The following macros show how -these operations can be specified in \ph: -@:PASCAL H}{\ph@> -@^system dependencies@> - -@d update_terminal fflush(term_out.f) /*empty the terminal output buffer*/ -@d clear_terminal fflush(term_in.f) /*clear the terminal input buffer*/ -@d wake_up_terminal do_nothing /*cancel the user's cancellation of output*/ - -@ We need a special routine to read the first line of \TeX\ input from -the user's terminal. This line is different because it is read before we -have opened the transcript file; there is sort of a ``chicken and -egg'' problem here. If the user types `\.{\\input paper}' on the first -line, or if some macro invoked by that line does such an \.{\\input}, -the transcript file will be named `\.{paper.log}'; but if no \.{\\input} -commands are performed during the first line of terminal input, the transcript -file will acquire its default name `\.{texput.log}'. (The transcript file -will not contain error messages generated by the first line before the -first \.{\\input} command.) -@.texput@> - -The first line is even more special if we are lucky enough to have an operating -system that treats \TeX\ differently from a run-of-the-mill \PASCAL\ object -program. It's nice to let the user start running a \TeX\ job by typing -a command line like `\.{tex paper}'; in such a case, \TeX\ will operate -as if the first line of input were `\.{paper}', i.e., the first line will -consist of the remainder of the command line, after the part that invoked -\TeX. - -The first line is special also because it may be read before \TeX\ has -input a format file. In such cases, normal error messages cannot yet -be given. The following code uses concepts that will be explained later. -(If the \PASCAL\ compiler does not support non-local |@!goto|\unskip, the -@^system dependencies@> -statement `|goto exit(0)|' should be replaced by something that -quietly terminates the program.) - -@<Report overflow of the input buffer, and abort@>= -if (format_ident==0) - {@+write_ln(term_out,"Buffer size exceeded!");exit(0); -@.Buffer size exceeded@> - } -else{@+cur_input.loc_field=first;cur_input.limit_field=last-1; - overflow("buffer size", buf_size); -@:TeX capacity exceeded buffer size}{\quad buffer size@> - } - -@ Different systems have different ways to get started. But regardless of -what conventions are adopted, the routine that initializes the terminal -should satisfy the following specifications: - -\yskip\textindent{1)}It should open file |term_in| for input from the - terminal. (The file |term_out| will already be open for output to the - terminal.) - -\textindent{2)}If the user has given a command line, this line should be - considered the first line of terminal input. Otherwise the - user should be prompted with `\.{**}', and the first line of input - should be whatever is typed in response. - -\textindent{3)}The first line of input, which might or might not be a - command line, should appear in locations |first| to |last-1| of the - |buffer| array. - -\textindent{4)}The global variable |loc| should be set so that the - character to be read next by \TeX\ is in |buffer[loc]|. This - character should not be blank, and we should have |loc < last|. - -\yskip\noindent(It may be necessary to prompt the user several times -before a non-blank line comes in. The prompt is `\.{**}' instead of the -later `\.*' because the meaning is slightly different: `\.{\\input}' need -not be typed immediately after~`\.{**}'.) - -@d loc cur_input.loc_field /*location of first unread character in |buffer|*/ - -@ The following program calls |input_command_line| -to retrieve a possible command line. -@^system dependencies@> - -@p static bool init_terminal(void) /*gets the terminal input started*/ -{@+ -t_open_in; -if (input_command_line()) return true; /* k\TeX\ */ -loop@+{@+wake_up_terminal;pascal_write(term_out,"**");update_terminal; -@.**@> - if (!input_ln(&term_in, true)) /*this shouldn't happen*/ - {@+write_ln(term_out); - pascal_write(term_out,"! End of file on the terminal... why?"); -@.End of file on the terminal@> - return false; - } - loc=first; - while ((loc < last)&&(buffer[loc]==' ')) incr(loc); - if (loc < last) - {@+return true; - /*return unless the line was all blank*/ - } - write_ln(term_out,"Please type the name of your input file."); - } -} - -@* String handling. -Control sequence names and diagnostic messages are variable-length strings -of eight-bit characters. Since \PASCAL\ does not have a well-developed string -mechanism, \TeX\ does all of its string processing by homegrown methods. - -Elaborate facilities for dynamic strings are not needed, so all of the -necessary operations can be handled with a simple data structure. -The array |str_pool| contains all of the (eight-bit) ASCII codes in all -of the strings, and the array |str_start| contains indices of the starting -points of each string. Strings are referred to by integer numbers, so that -string number |s| comprises the characters |str_pool[j]| for -|str_start[s] <= j < str_start[s+1]|. Additional integer variables -|pool_ptr| and |str_ptr| indicate the number of entries used so far -in |str_pool| and |str_start|, respectively; locations -|str_pool[pool_ptr]| and |str_start[str_ptr]| are -ready for the next string to be allocated. - -String numbers 0 to 255 are reserved for strings that correspond to single -ASCII characters. This is in accordance with the conventions of \.{WEB}, -@.WEB@> -which converts single-character strings into the ASCII code number of the -single character involved, while it converts other strings into integers -and builds a string pool file. Thus, when the string constant \.{"."} appears -in the program below, \.{WEB} converts it into the integer 46, which is the -ASCII code for a period, while \.{WEB} will convert a string like \.{"hello"} -into some integer greater than~255. String number 46 will presumably be the -single character `\..'; but some ASCII codes have no standard visible -representation, and \TeX\ sometimes needs to be able to print an arbitrary -ASCII character, so the first 256 strings are used to specify exactly what -should be printed for each of the 256 possibilities. - -Elements of the |str_pool| array must be ASCII codes that can actually -be printed; i.e., they must have an |xchr| equivalent in the local -character set. (This restriction applies only to preloaded strings, -not to those generated dynamically by the user.) - -Some \PASCAL\ compilers won't pack integers into a single byte unless the -integers lie in the range |-128 dotdot 127|. To accommodate such systems -we access the string pool only via macros that can easily be redefined. -@^system dependencies@> - -@d si(A) A /*convert from |ASCII_code| to |packed_ASCII_code|*/ -@d so(A) A /*convert from |packed_ASCII_code| to |ASCII_code|*/ - -@<Types...@>= -typedef int32_t pool_pointer; /*for variables that point into |str_pool|*/ -typedef int32_t str_number; /*for variables that point into |str_start|*/ -typedef uint8_t packed_ASCII_code; /*elements of |str_pool| array*/ - -@ @<Glob...@>= -packed_ASCII_code @!str_pool[pool_size+1]; /*the characters*/ -pool_pointer @!str_start[max_strings+1]; /*the starting pointers*/ -static pool_pointer @!pool_ptr; /*first unused position in |str_pool|*/ -static str_number @!str_ptr; /*number of the current string being created*/ -static pool_pointer @!init_pool_ptr; /*the starting value of |pool_ptr|*/ -static str_number @!init_str_ptr; /*the starting value of |str_ptr|*/ - -@ Several of the elementary string operations are performed using \.{WEB} -macros instead of \PASCAL\ procedures, because many of the -operations are done quite frequently and we want to avoid the -overhead of procedure calls. For example, here is -a simple macro that computes the length of a string. -@.WEB@> - -@d length(A) (str_start[A+1]-str_start[A]) /*the number of characters - in string number \#*/ - -@ The length of the current string is called |cur_length|: - -@d cur_length (pool_ptr-str_start[str_ptr]) - -@ Strings are created by appending character codes to |str_pool|. -The |append_char| macro, defined here, does not check to see if the -value of |pool_ptr| has gotten too high; this test is supposed to be -made before |append_char| is used. There is also a |flush_char| -macro, which erases the last character appended. - -To test if there is room to append |l| more characters to |str_pool|, -we shall write |str_room(l)|, which aborts \TeX\ and gives an -apologetic error message if there isn't enough room. - -@d append_char(A) /*put |ASCII_code| \# at the end of |str_pool|*/ -{@+str_pool[pool_ptr]=si(A);incr(pool_ptr); -} -@d flush_char decr(pool_ptr) /*forget the last character in the pool*/ -@d str_room(A) /*make sure that the pool hasn't overflowed*/ - {@+if (pool_ptr+A > pool_size) - overflow("pool size", pool_size-init_pool_ptr); -@:TeX capacity exceeded pool size}{\quad pool size@> - } - -@ Once a sequence of characters has been appended to |str_pool|, it -officially becomes a string when the function |make_string| is called. -This function returns the identification number of the new string as its -value. - -@p static str_number make_string(void) /*current string enters the pool*/ -{@+if (str_ptr==max_strings) - overflow("number of strings", max_strings-init_str_ptr); -@:TeX capacity exceeded number of strings}{\quad number of strings@> -incr(str_ptr);str_start[str_ptr]=pool_ptr; -return str_ptr-1; -} - -@ To destroy the most recently made string, we say |flush_string|. - -@d flush_string {@+decr(str_ptr);pool_ptr=str_start[str_ptr]; - } - -@ The following subroutine compares string |s| with another string of the -same length that appears in |buffer| starting at position |k|; -the result is |true| if and only if the strings are equal. -Empirical tests indicate that |str_eq_buf| is used in such a way that -it tends to return |true| about 80 percent of the time. - -@p static bool str_eq_buf(str_number @!s, int @!k) - /*test equality of strings*/ -{@+ /*loop exit*/ -pool_pointer j; /*running index*/ -bool @!result; /*result of comparison*/ -j=str_start[s]; -while (j < str_start[s+1]) - {@+if (so(str_pool[j])!=buffer[k]) - {@+result=false;goto not_found; - } - incr(j);incr(k); - } -result=true; -not_found: return result; -} - -@ Here is a similar routine, but it compares two strings in the string pool, -and it does not assume that they have the same length. - -@p static bool strn_eq_str(str_number @!s, str_number @!t) - /*test equality of strings*/ -{@+ /*loop exit*/ -pool_pointer j, @!k; /*running indices*/ -bool @!result; /*result of comparison*/ -result=false; -if (length(s)!=length(t)) goto not_found; -j=str_start[s];k=str_start[t]; -while (j < str_start[s+1]) - {@+if (str_pool[j]!=str_pool[k]) goto not_found; - incr(j);incr(k); - } -result=true; -not_found: return result; -} - -static bool str_eq_str(str_number @!s, char *@!t) - /*test equality of strings*/ -{@+int j, @!k; /*running indices*/ -if (length(s)!=(int)strlen(t)) return false; -j=str_start[s];k=0; -while (j < str_start[s+1]) - if (str_pool[j++]!=t[k++]) return false; -return true; -} - -@ The initial values of |str_pool|, |str_start|, |pool_ptr|, -and |str_ptr| are computed by the \.{INITEX} program, based in part -on the information that \.{WEB} has output while processing \TeX. -@.INITEX@> -@^string pool@> - -@p -static void get_strings_started(void) /*initializes the string pool*/ -{@+ -int k, @!l; /*small indices or counters*/ -pool_ptr=0;str_ptr=0;str_start[0]=0; -@<Make the first 256 strings@>; -@<Add the empty string to the string pool@>; -} - -@ @d app_lc_hex(A) l=A; - if (l < 10) append_char(l+'0')@;@+else append_char(l-10+'a') - -@<Make the first 256...@>= -for (k=0; k<=255; k++) - {@+if ((@<Character |k| cannot be printed@>)) - {@+append_char('^');append_char('^'); - if (k < 0100) append_char(k+0100)@; - else if (k < 0200) append_char(k-0100)@; - else{@+app_lc_hex(k/16);app_lc_hex(k%16); - } - } - else append_char(k); - make_string(); - } - -@ The first 128 strings will contain 95 standard ASCII characters, and the -other 33 characters will be printed in three-symbol form like `\.{\^\^A}' -unless a system-dependent change is made here. Installations that have -an extended character set, where for example |xchr[032]==@t\.{\'^^Z\'}@>|, -would like string 032 to be the single character 032 instead of the -three characters 0136, 0136, 0132 (\.{\^\^Z}). On the other hand, -even people with an extended character set will want to represent string -015 by \.{\^\^M}, since 015 is |carriage_return|; the idea is to -produce visible strings instead of tabs or line-feeds or carriage-returns -or bell-rings or characters that are treated anomalously in text files. - -Unprintable characters of codes 128--255 are, similarly, rendered -\.{\^\^80}--\.{\^\^ff}. - -The boolean expression defined here should be |true| unless \TeX\ -internal code number~|k| corresponds to a non-troublesome visible -symbol in the local character set. An appropriate formula for the -extended character set recommended in {\sl The \TeX book\/} would, for -example, be `|k in[0, 010 dotdot 012, 014, 015, 033, 0177 dotdot 0377]|'. -If character |k| cannot be printed, and |k < 0200|, then character |k+0100| or -|k-0100| must be printable; moreover, ASCII codes |[041 dotdot 046, -060 dotdot 071, 0136, 0141 dotdot 0146, 0160 dotdot 0171]| must be printable. -Thus, at least 80 printable characters are needed. -@:TeXbook}{\sl The \TeX book@> -@^character set dependencies@> -@^system dependencies@> - -@<Character |k| cannot be printed@>= - (k < ' ')||(k > '~') - -@ The |pool_file| variable is no longer needed and has been removed. - -@ Instead of reading the other strings from the \.{TEX.POOL} file, -it is sufficient here to add the empty string. -@<Add the empty string to the string pool@>= -make_string(); - -@ Without a string pool file there is no need for a pool check sum either. -But this is a convenient place to define the function |s_no| that will -add literal strings to the string pool at runtime, thereby obtaining their -string number. - -@p int s_no(const char *str) -{@+ - if (str[0]==0) return empty_string; - if (str[1]==0) return str[0]; - str_room(strlen(str)); - while (*str!=0) append_char(*str++); - return make_string(); -} - -@* On-line and off-line printing. -Messages that are sent to a user's terminal and to the transcript-log file -are produced by several `|print|' procedures. These procedures will -direct their output to a variety of places, based on the setting of -the global variable |selector|, which has the following possible -values: - -\yskip -\hang |term_and_log|, the normal setting, prints on the terminal and on the - transcript file. - -\hang |log_only|, prints only on the transcript file. - -\hang |term_only|, prints only on the terminal. - -\hang |no_print|, doesn't print at all. This is used only in rare cases - before the transcript file is open. - -\hang |pseudo|, puts output into a cyclic buffer that is used - by the |show_context| routine; when we get to that routine we shall discuss - the reasoning behind this curious mode. - -\hang |new_string|, appends the output to the current string in the - string pool. - -\hang 0 to 15, prints on one of the sixteen files for \.{\\write} output. - -\yskip -\noindent The symbolic names `|term_and_log|', etc., have been assigned -numeric codes that satisfy the convenient relations |no_print+1==term_only|, -|no_print+2==log_only|, |term_only+2==log_only+1==term_and_log|. - -Three additional global variables, |tally| and |term_offset| and -|file_offset|, record the number of characters that have been printed -since they were most recently cleared to zero. We use |tally| to record -the length of (possibly very long) stretches of printing; |term_offset| -and |file_offset|, on the other hand, keep track of how many characters -have appeared so far on the current line that has been output to the -terminal or to the transcript file, respectively. - -@d no_print 16 /*|selector| setting that makes data disappear*/ -@d term_only 17 /*printing is destined for the terminal only*/ -@d log_only 18 /*printing is destined for the transcript file only*/ -@d term_and_log 19 /*normal |selector| setting*/ -@d pseudo 20 /*special |selector| setting for |show_context|*/ -@d new_string 21 /*printing is deflected to the string pool*/ -@d max_selector 21 /*highest selector setting*/ - -@<Glob...@>= -static alpha_file @!log_file; /*transcript of \TeX\ session*/ -static int @!selector; /*where to print a message*/ -static int8_t @!dig[23]; /*digits in a number being output*/ -static int @!tally; /*the number of characters recently printed*/ -static int @!term_offset; - /*the number of characters on the current terminal line*/ -static int @!file_offset; - /*the number of characters on the current file line*/ -static ASCII_code @!trick_buf[error_line+1]; /*circular buffer for - pseudoprinting*/ -static int @!trick_count; /*threshold for pseudoprinting, explained later*/ -static int @!first_count; /*another variable for pseudoprinting*/ - -@ @<Initialize the output routines@>= -selector=term_only;tally=0;term_offset=0;file_offset=0; - -@ Macro abbreviations for output to the terminal and to the log file are -defined here for convenience. Some systems need special conventions -for terminal output, and it is possible to adhere to those conventions -by changing |wterm|, |wterm_ln|, and |wterm_cr| in this section. -@^system dependencies@> - -@<Basic printing procedures@>= -#define put(F) @[fwrite(&((F).d),sizeof((F).d),1,(F).f)@] -#define get(F) @[fread(&((F).d),sizeof((F).d),1,(F).f)@] - -#define pascal_close(F) @[fclose((F).f)@] -#define eof(F) @[feof((F).f)@] -#define eoln(F) @[((F).d=='\n'||eof(F))@] -#define erstat(F) @[((F).f==NULL?-1:ferror((F).f))@] - -#define pascal_read(F,X) @[((X)=(F).d,get(F))@] -#define read_ln(F) @[do get(F); while (!eoln(F))@] - -#define pascal_write(F, FMT,...) @[fprintf(F.f,FMT,## __VA_ARGS__)@] -#define write_ln(F,...) @[pascal_write(F,__VA_ARGS__"\n")@] - -#define wterm(FMT,...) @[pascal_write(term_out,FMT, ## __VA_ARGS__)@] -#define wterm_ln(FMT,...) @[wterm(FMT "\n", ## __VA_ARGS__)@] -#define wterm_cr @[pascal_write(term_out,"\n")@] -#define wlog(FMT, ...) @[pascal_write(log_file,FMT, ## __VA_ARGS__)@] -#define wlog_ln(FMT, ...) @[wlog(FMT "\n", ## __VA_ARGS__)@] -#define wlog_cr @[pascal_write(log_file,"\n")@] - -@ To end a line of text output, we call |print_ln|. - -@<Basic print...@>= -void print_ln(void) /*prints an end-of-line*/ -{@+switch (selector) { -case term_and_log: {@+wterm_cr;wlog_cr; - term_offset=0;file_offset=0; - } @+break; -case log_only: {@+wlog_cr;file_offset=0; - } @+break; -case term_only: {@+wterm_cr;term_offset=0; - } @+break; -case no_print: case pseudo: case new_string: do_nothing;@+break; -default:write_ln(write_file[selector]); -} @/ -} /*|tally| is not affected*/ - -@ The |print_char| procedure sends one character to the desired destination, -using the |xchr| array to map it into an external character compatible with -|input_ln|. All printing comes through |print_ln| or |print_char|. - -@<Basic printing...@>= -void print_char(ASCII_code @!s) /*prints a single character*/ -{@+ -if (@<Character |s| is the current new-line character@>) - if (selector < pseudo) - {@+print_ln();return; - } -switch (selector) { -case term_and_log: {@+wterm("%c",xchr[s]);wlog("%c",xchr[s]); - incr(term_offset);incr(file_offset); - if (term_offset==max_print_line) - {@+wterm_cr;term_offset=0; - } - if (file_offset==max_print_line) - {@+wlog_cr;file_offset=0; - } - } @+break; -case log_only: {@+wlog("%c",xchr[s]);incr(file_offset); - if (file_offset==max_print_line) print_ln(); - } @+break; -case term_only: {@+wterm("%c",xchr[s]);incr(term_offset); - if (term_offset==max_print_line) print_ln(); - } @+break; -case no_print: do_nothing;@+break; -case pseudo: if (tally < trick_count) trick_buf[tally%error_line]=s;@+break; -case new_string: {@+if (pool_ptr < pool_size) append_char(s); - } @+break; /*we drop characters if the string space is full*/ -default:pascal_write(write_file[selector],"%c", xchr[s]); -} @/ -incr(tally); -} - -@ An entire string is output by calling |print|. Note that if we are outputting -the single standard ASCII character \.c, we could call |print('c')|, since -|'c'==99| is the number of a single-character string, as explained above. But -|print_char('c')| is quicker, so \TeX\ goes directly to the |print_char| -routine when it knows that this is safe. (The present implementation -assumes that it is always safe to print a visible ASCII character.) -@^system dependencies@> - -@<Basic print...@>= -void print(char *s) /* the simple version */ -{ while (*s!=0) print_char(*s++);@+ -} - -static void printn(int @!s) /*prints string |s|*/ -{@+ -pool_pointer j; /*current character code position*/ -int @!nl; /*new-line character to restore*/ -if (s >= str_ptr) {print("???"); return;}/*this can't happen*/ -@.???@> -else if (s < 256) - if (s < 0) { print("???");return; } /*can't happen*/ - else{@+if (selector > pseudo) - {@+print_char(s);return; /*internal strings are not expanded*/ - } - if ((@<Character |s| is the current new-line character@>)) - if (selector < pseudo) - {@+print_ln();return; - } - nl=new_line_char;new_line_char=-1; - /*temporarily disable new-line character*/ - j=str_start[s]; - while (j < str_start[s+1]) - {@+print_char(so(str_pool[j]));incr(j); - } - new_line_char=nl;return; - } -j=str_start[s]; -while (j < str_start[s+1]) - {@+print_char(so(str_pool[j]));incr(j); - } -} - -@ Control sequence names, file names, and strings constructed with -\.{\\string} might contain |ASCII_code| values that can't -be printed using |print_char|. Therefore we use |slow_print| for them: - -@<Basic print...@>= -static void slow_print(int @!s) /*prints string |s|*/ -{@+pool_pointer j; /*current character code position*/ -if ((s >= str_ptr)||(s < 256)) printn(s); -else{@+j=str_start[s]; - while (j < str_start[s+1]) - {@+printn(so(str_pool[j]));incr(j); - } - } -} - -@ Here is the very first thing that \TeX\ prints: a headline that identifies -the version number and format package. The |term_offset| variable is temporarily -incorrect, but the discrepancy is not serious since we assume that this -part of the program is system dependent. -@^system dependencies@> - -k\TeX, according to the conventions of \TeX\ Live, - prints the |dump_name| if no format identifier is known. -@<Initialize the output...@>= -wterm("%s",banner); -if (format_ident==0) wterm_ln(" (preloaded format=%s)", dump_name); -else{@+slow_print(format_ident);print_ln(); - } -update_terminal; - -@ The procedure |print_nl| is like |print|, but it makes sure that the -string appears at the beginning of a new line. - -@<Basic print...@>= -void print_nl(char *@!s) /*prints string |s| at beginning of line*/ -{@+if (((term_offset > 0)&&(odd(selector)))||@| - ((file_offset > 0)&&(selector >= log_only))) print_ln(); -print(s); -} - -@ The procedure |print_esc| prints a string that is preceded by -the user's escape character (which is usually a backslash). - -@<Basic print...@>= -static void printn_esc(str_number @!s) /*prints escape character, then |s|*/ -{@+int c; /*the escape character code*/ -@<Set variable |c| to the current escape character@>; -if (c >= 0) if (c < 256) printn(c); -slow_print(s); -} - -static void print_esc(char *@!s) /*the fast way*/ -{@+int c; /*the escape character code*/ -@<Set variable |c| to the current escape character@>; -if (c >= 0) if (c < 256) printn(c); -print(s); -} - -@ An array of digits in the range |0 dotdot 15| is printed by |print_the_digs|. - -@<Basic print...@>= -static void print_the_digs(eight_bits @!k) - /*prints |dig[k-1]|$\,\ldots\,$|dig[0]|*/ -{@+while (k > 0) - {@+decr(k); - if (dig[k] < 10) print_char('0'+dig[k]); - else print_char('A'-10+dig[k]); - } -} - -@ The following procedure, which prints out the decimal representation of a -given integer |n|, has been written carefully so that it works properly -if |n==0| or if |(-n)| would cause overflow. It does not apply |%| or |/| -to negative arguments, since such operations are not implemented consistently -by all \PASCAL\ compilers. - -@<Basic print...@>= -void print_int(int @!n) /*prints an integer in decimal form*/ -{@+int k; /*index to current digit; we assume that $\vert n\vert<10^{23}$*/ -int @!m; /*used to negate |n| in possibly dangerous cases*/ -k=0; -if (n < 0) - {@+print_char('-'); - if (n > -100000000) negate(n); - else{@+m=-1-n;n=m/10;m=(m%10)+1;k=1; - if (m < 10) dig[0]=m; - else{@+dig[0]=0;incr(n); - } - } - } -@/do@+{dig[k]=n%10;n=n/10;incr(k); -}@+ while (!(n==0)); -print_the_digs(k); -} - -@ Here is a trivial procedure to print two digits; it is usually called with -a parameter in the range |0 <= n <= 99|. - -@p static void print_two(int @!n) /*prints two least significant digits*/ -{@+n=abs(n)%100;print_char('0'+(n/10)); -print_char('0'+(n%10)); -} - -@ Hexadecimal printing of nonnegative integers is accomplished by |print_hex|. - -@p static void print_hex(int @!n) - /*prints a positive integer in hexadecimal form*/ -{@+int k; /*index to current digit; we assume that $0\le n<16^{22}$*/ -k=0;print_char('"'); -@/do@+{dig[k]=n%16;n=n/16;incr(k); -}@+ while (!(n==0)); -print_the_digs(k); -} - -@ Old versions of \TeX\ needed a procedure called |print_ASCII| whose function -is now subsumed by |print|. We retain the old name here as a possible aid to -future software arch\ae ologists. - -@d print_ASCII printn - -@ Roman numerals are produced by the |print_roman_int| routine. Readers -who like puzzles might enjoy trying to figure out how this tricky code -works; therefore no explanation will be given. Notice that 1990 yields -\.{mcmxc}, not \.{mxm}. - -@p static void print_roman_int(int @!n) -{@+ -pool_pointer j, @!k; /*mysterious indices into |mystery|*/ -nonnegative_integer @!u, @!v; /*mysterious numbers*/ -const char mystery[] ="m2d5c2l5x2v5i"; -j=0;v=1000; -loop@+{@+while (n >= v) - {@+print_char(so(mystery[j]));n=n-v; - } - if (n <= 0) return; /*nonpositive input produces no output*/ - k=j+2;u=v/(so(mystery[k-1])-'0'); - if (mystery[k-1]==si('2')) - {@+k=k+2;u=u/(so(mystery[k-1])-'0'); - } - if (n+u >= v) - {@+print_char(so(mystery[k]));n=n+u; - } - else{@+j=j+2;v=v/(so(mystery[j-1])-'0'); - } - } -} - -@ The |print| subroutine will not print a string that is still being -created. The following procedure will. - -@p static void print_current_string(void) /*prints a yet-unmade string*/ -{@+pool_pointer j; /*points to current character code*/ -j=str_start[str_ptr]; -while (j < pool_ptr) - {@+print_char(so(str_pool[j]));incr(j); - } -} - -@ Here is a procedure that asks the user to type a line of input, -assuming that the |selector| setting is either |term_only| or |term_and_log|. -The input is placed into locations |first| through |last-1| of the -|buffer| array, and echoed on the transcript file if appropriate. - -This procedure is never called when |interaction < scroll_mode|. - -@d prompt_input(A) {@+wake_up_terminal;print(A);term_input(); - } /*prints a string and gets a line of input*/ - -@p static void term_input(void) /*gets a line from the terminal*/ -{@+int k; /*index into |buffer|*/ -update_terminal; /*now the user sees the prompt for sure*/ -if (!input_ln(&term_in, true)) fatal_error("End of file on the terminal!"); -@.End of file on the terminal@> -term_offset=0; /*the user's line ended with \<\rm return>*/ -decr(selector); /*prepare to echo the input*/ -if (last!=first) for (k=first; k<=last-1; k++) printn(buffer[k]); -print_ln();incr(selector); /*restore previous status*/ -} - -@* Reporting errors. -When something anomalous is detected, \TeX\ typically does something like this: -$$\vbox{\halign{#\hfil\cr -|print_err("Something anomalous has been detected");|\cr -|help3("This is the first line of my offer to help.")|\cr -|("This is the second line. I'm trying to")|\cr -|("explain the best way for you to proceed.");|\cr -|error;|\cr}}$$ -A two-line help message would be given using |help2|, etc.; these informal -helps should use simple vocabulary that complements the words used in the -official error message that was printed. (Outside the U.S.A., the help -messages should preferably be translated into the local vernacular. Each -line of help is at most 60 characters long, in the present implementation, -so that |max_print_line| will not be exceeded.) - -The |print_err| procedure supplies a `\.!' before the official message, -and makes sure that the terminal is awake if a stop is going to occur. -The |error| procedure supplies a `\..' after the official message, then it -shows the location of the error; and if |interaction==error_stop_mode|, -it also enters into a dialog with the user, during which time the help -message may be printed. -@^system dependencies@> - -@<Error handling...@>= -void print_err(char *s) -{@+if (interaction==error_stop_mode) wake_up_terminal; - if (filelineerrorstylep) print_file_line(); /* k\TeX\ */ - else print_nl("! "); - print(s); -} - -@ The global variable |interaction| has four settings, representing increasing -amounts of user interaction: - -@d batch_mode 0 /*omits all stops and omits terminal output*/ -@d nonstop_mode 1 /*omits all stops*/ -@d scroll_mode 2 /*omits error stops*/ -@d error_stop_mode 3 /*stops at every opportunity to interact*/ - -@<Glob...@>= -int @!interaction; /*current level of interaction*/ - -@ @<Set init...@>=interaction=error_stop_mode; - -@ \TeX\ is careful not to call |error| when the print |selector| setting -might be unusual. The only possible values of |selector| at the time of -error messages are - -\yskip\hang|no_print| (when |interaction==batch_mode| - and |log_file| not yet open); - -\hang|term_only| (when |interaction > batch_mode| and |log_file| not yet open); - -\hang|log_only| (when |interaction==batch_mode| and |log_file| is open); - -\hang|term_and_log| (when |interaction > batch_mode| and |log_file| is open). - -@<Initialize the print |selector| based on |interaction|@>= -if (interaction==batch_mode) selector=no_print;@+else selector=term_only - -@ A global variable |deletions_allowed| is set |false| if the |get_next| -routine is active when |error| is called; this ensures that |get_next| -and related routines like |get_token| will never be called recursively. -A similar interlock is provided by |set_box_allowed|. -@^recursion@> - -The global variable |history| records the worst level of error that -has been detected. It has four possible values: |spotless|, |warning_issued|, -|error_message_issued|, and |fatal_error_stop|. - -Another global variable, |error_count|, is increased by one when an -|error| occurs without an interactive dialog, and it is reset to zero at -the end of every paragraph. If |error_count| reaches 100, \TeX\ decides -that there is no point in continuing further. - -@d spotless 0 /*|history| value when nothing has been amiss yet*/ -@d warning_issued 1 /*|history| value when |begin_diagnostic| has been called*/ -@d error_message_issued 2 /*|history| value when |error| has been called*/ -@d fatal_error_stop 3 /*|history| value when termination was premature*/ - -@<Glob...@>= -static bool @!deletions_allowed; /*is it safe for |error| to call |get_token|?*/ -static bool @!set_box_allowed; /*is it safe to do a \.{\\setbox} assignment?*/ -static int @!history; /*has the source input been clean so far?*/ -static int @!error_count; /*the number of scrolled errors since the - last paragraph ended*/ - -@ The value of |history| is initially |fatal_error_stop|, but it will -be changed to |spotless| if \TeX\ survives the initialization process. - -@<Set init...@>= -deletions_allowed=true;set_box_allowed=true; -error_count=0; /*|history| is initialized elsewhere*/ - -@ Since errors can be detected almost anywhere in \TeX, we want to declare the -error procedures near the beginning of the program. But the error procedures -in turn use some other procedures, which need to be declared |forward| -before we get to |error| itself. - -It is possible for |error| to be called recursively if some error arises -when |get_token| is being used to delete a token, and/or if some fatal error -occurs while \TeX\ is trying to fix a non-fatal one. But such recursion -@^recursion@> -is never more than two levels deep. - -@<Error handling...@>= -static void normalize_selector(void);@/ -static void get_token(void);@/ -static void term_input(void);@/ -static void show_context(void);@/ -static void begin_file_reading(void);@/ -void open_log_file(void);@/ -static void close_files_and_terminate(void);@/ -static void clear_for_error_prompt(void);@/ -static void give_err_help(void);@/ -#ifdef @!DEBUG -static void debug_help(void); -#else -#define debug_help() do_nothing -#endif - -@ Individual lines of help are recorded in the array |help_line|, which -contains entries in positions |0 dotdot(help_ptr-1)|. They should be printed -in reverse order, i.e., with |help_line[0]| appearing last. - -@d hlp1(A) help_line[0]=A;@+} -@d hlp2(A, B) help_line[1]=A;help_line[0]=B;@+} -@d hlp3(A, B, C) help_line[2]=A;help_line[1]=B;help_line[0]=C;@+} -@d hlp4(A, B, C, D) help_line[3]=A;help_line[2]=B;help_line[1]=C;help_line[0]=D;@+} -@d hlp5(A, B, C, D, E) help_line[4]=A;help_line[3]=B;help_line[2]=C;help_line[1]=D;help_line[0]=E;@+} -@d hlp6(A, B, C, D, E, F) help_line[5]=A;help_line[4]=B;help_line[3]=C;help_line[2]=D;help_line[1]=E;help_line[0]=F;@+} -@d help0 help_ptr=0 /*sometimes there might be no help*/ -@d help1(A) @+{@+help_ptr=1;hlp1(A) /*use this with one help line*/ -@d help2(A, B) @+{@+help_ptr=2;hlp2(A, B) /*use this with two help lines*/ -@d help3(A, B, C) @+{@+help_ptr=3;hlp3(A, B, C) /*use this with three help lines*/ -@d help4(A, B, C, D) @+{@+help_ptr=4;hlp4(A, B, C, D) /*use this with four help lines*/ -@d help5(A, B, C, D, E) @+{@+help_ptr=5;hlp5(A, B, C, D, E) /*use this with five help lines*/ -@d help6(A, B, C, D, E, F) @+{@+help_ptr=6;hlp6(A, B, C, D, E, F) /*use this with six help lines*/ - -@<Glob...@>= -static char *@!help_line[6]; /*helps for the next |error|*/ -static int @!help_ptr; /*the number of help lines present*/ -static bool @!use_err_help; /*should the |err_help| list be shown?*/ - -@ @<Set init...@>= -help_ptr=0;use_err_help=false; - -@ The |jump_out| procedure just cuts across all active procedure levels and -goes to |end_of_TEX|. This is the only nontrivial |@!goto| statement in the -whole program. It is used when there is no recovery from a particular error. - -Some \PASCAL\ compilers do not implement non-local |goto| statements. -@^system dependencies@> -In such cases the body of |jump_out| should simply be -`|close_files_and_terminate|;\thinspace' followed by a call on some system -procedure that quietly terminates the program. - -@<Error hand...@>= -static void jump_out(void) -{@+ close_files_and_terminate(); exit(0); -} - -@ Here now is the general |error| routine. - -@<Error hand...@>= -static void error(void) /*completes the job of error reporting*/ -{@+ -ASCII_code c; /*what the user types*/ -int @!s1, @!s2, @!s3, @!s4; - /*used to save global variables when deleting tokens*/ -if (history < error_message_issued) history=error_message_issued; -print_char('.');show_context(); -if (interaction==error_stop_mode) - @<Get user's advice and |return|@>; -incr(error_count); -if (error_count==100) - {@+print_nl("(That makes 100 errors; please try again.)"); -@.That makes 100 errors...@> - history=fatal_error_stop;jump_out(); - } -@<Put help message on the transcript file@>; -} - -@ @<Get user's advice...@>= -loop@+{@+resume: if (interaction!=error_stop_mode) return; - clear_for_error_prompt();prompt_input("? "); -@.?\relax@> - if (last==first) return; - c=buffer[first]; - if (c >= 'a') c=c+'A'-'a'; /*convert to uppercase*/ - @<Interpret code |c| and |return| if done@>; - } - -@ It is desirable to provide an `\.E' option here that gives the user -an easy way to return from \TeX\ to the system editor, with the offending -line ready to be edited. But such an extension requires some system -wizardry, so the present implementation simply types out the name of the -file that should be -edited and the relevant line number. -@^system dependencies@> - -There is a secret `\.D' option available when the debugging routines haven't -been commented~out. -@^debugging@> - -@<Interpret code |c| and |return| if done@>= -switch (c) { -case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': if (deletions_allowed) - @<Delete \(c)|c-"0"| tokens and |goto continue|@>@;@+break; -@t\4\4@>@; -#ifdef @!DEBUG -case 'D': {@+debug_help();goto resume;@+} -#endif -case 'E': if (base_ptr > 0) if (input_stack[base_ptr].name_field >= 256) - {@+print_nl("You want to edit file "); -@.You want to edit file x@> - slow_print(input_stack[base_ptr].name_field); - print(" at line ");print_int(line); - interaction=scroll_mode;jump_out(); - } @+break; -case 'H': @<Print the help information and |goto continue|@>@; -case 'I': @<Introduce new material from the terminal and |return|@>@; -case 'Q': case 'R': case 'S': @<Change the interaction level and |return|@>@; -case 'X': {@+interaction=scroll_mode;jump_out(); - } @+break; -default:do_nothing; -} @/ -@<Print the menu of available options@>@; - -@ @<Print the menu...@>= -{@+print("Type <return> to proceed, S to scroll future error messages,");@/ -@.Type <return> to proceed...@> -print_nl("R to run without stopping, Q to run quietly,");@/ -print_nl("I to insert something, "); -if (base_ptr > 0) if (input_stack[base_ptr].name_field >= 256) - print("E to edit your file,"); -if (deletions_allowed) - print_nl("1 or ... or 9 to ignore the next 1 to 9 tokens of input,"); -print_nl("H for help, X to quit."); -} - -@ Here the author of \TeX\ apologizes for making use of the numerical -relation between |'Q'|, |'R'|, |'S'|, and the desired interaction settings -|batch_mode|, |nonstop_mode|, |scroll_mode|. -@^Knuth, Donald Ervin@> - -@<Change the interaction...@>= -{@+error_count=0;interaction=batch_mode+c-'Q'; -print("OK, entering "); -switch (c) { -case 'Q': {@+print_esc("batchmode");decr(selector); - } @+break; -case 'R': print_esc("nonstopmode");@+break; -case 'S': print_esc("scrollmode"); -} /*there are no other cases*/ -print("...");print_ln();update_terminal;return; -} - -@ When the following code is executed, |buffer[(first+1)dotdot(last-1)]| may -contain the material inserted by the user; otherwise another prompt will -be given. In order to understand this part of the program fully, you need -to be familiar with \TeX's input stacks. - -@<Introduce new material...@>= -{@+begin_file_reading(); /*enter a new syntactic level for terminal input*/ - /*now |state==mid_line|, so an initial blank space will count as a blank*/ -if (last > first+1) - {@+loc=first+1;buffer[first]=' '; - } -else{@+prompt_input("insert>");loc=first; -@.insert>@> - } -first=last; -cur_input.limit_field=last-1; /*no |end_line_char| ends this line*/ -return; -} - -@ We allow deletion of up to 99 tokens at a time. - -@<Delete \(c)|c-"0"| tokens...@>= -{@+s1=cur_tok;s2=cur_cmd;s3=cur_chr;s4=align_state; -align_state=1000000;OK_to_interrupt=false; -if ((last > first+1)&&(buffer[first+1] >= '0')&&(buffer[first+1] <= '9')) - c=c*10+buffer[first+1]-'0'*11; -else c=c-'0'; -while (c > 0) - {@+get_token(); /*one-level recursive call of |error| is possible*/ - decr(c); - } -cur_tok=s1;cur_cmd=s2;cur_chr=s3;align_state=s4;OK_to_interrupt=true; -help2("I have just deleted some text, as you asked.",@/ -"You can now delete more, or insert, or whatever."); -show_context();goto resume; -} - -@ @<Print the help info...@>= -{@+if (use_err_help) - {@+give_err_help();use_err_help=false; - } -else{@+if (help_ptr==0) - help2("Sorry, I don't know how to help in this situation.",@/ - @t\kern1em@>"Maybe you should try asking a human?"); - @/do@+{decr(help_ptr);print(help_line[help_ptr]);print_ln(); - }@+ while (!(help_ptr==0)); - } -help4("Sorry, I already gave what help I could...",@/ - "Maybe you should try asking a human?",@/ - "An error might have occurred before I noticed any problems.",@/ - "``If all else fails, read the instructions.'");@/ -goto resume; -} - -@ @<Put help message on the transcript file@>= -if (interaction > batch_mode) decr(selector); /*avoid terminal output*/ -if (use_err_help) - {@+print_ln();give_err_help(); - } -else while (help_ptr > 0) - {@+decr(help_ptr);print_nl(help_line[help_ptr]); - } -print_ln(); -if (interaction > batch_mode) incr(selector); /*re-enable terminal output*/ -print_ln() - -@ A dozen or so error messages end with a parenthesized integer, so we -save a teeny bit of program space by declaring the following procedure: - -@p static void int_error(int @!n) -{@+print(" (");print_int(n);print_char(')');error(); -} - -@ In anomalous cases, the print selector might be in an unknown state; -the following subroutine is called to fix things just enough to keep -running a bit longer. - -@p static void normalize_selector(void) -{@+if (log_opened) selector=term_and_log; -else selector=term_only; -if (job_name==0) open_log_file(); -if (interaction==batch_mode) decr(selector); -} - -@ The following procedure prints \TeX's last words before dying. - -@d succumb {@+if (interaction==error_stop_mode) - interaction=scroll_mode; /*no more interaction*/ - if (log_opened) error(); - if (interaction > batch_mode) debug_help(); - history=fatal_error_stop;jump_out(); /*irrecoverable error*/ - } - -@<Error hand...@>= -void fatal_error(char *@!s) /*prints |s|, and that's it*/ -{@+normalize_selector();@/ -print_err("Emergency stop");help1(s);succumb; -@.Emergency stop@> -} - -@ Here is the most dreaded error message. - -@<Error hand...@>= -void overflow(char *@!s, int @!n) /*stop due to finiteness*/ -{@+normalize_selector(); -print_err("TeX capacity exceeded, sorry ["); -@.TeX capacity exceeded ...@> -print(s);print_char('=');print_int(n);print_char(']'); -help2("If you really absolutely need more capacity,",@/ - "you can ask a wizard to enlarge me."); -succumb; -} - -@ The program might sometime run completely amok, at which point there is -no choice but to stop. If no previous error has been detected, that's bad -news; a message is printed that is really intended for the \TeX\ -maintenance person instead of the user (unless the user has been -particularly diabolical). The index entries for `this can't happen' may -help to pinpoint the problem. -@^dry rot@> - -@<Error hand...@>= -void confusion(char *@!s) - /*consistency check violated; |s| tells where*/ -{@+normalize_selector(); -if (history < error_message_issued) - {@+print_err("This can't happen (");print(s);print_char(')'); -@.This can't happen@> - help1("I'm broken. Please show this to someone who can fix can fix"); - } -else{@+print_err("I can't go on meeting you like this"); -@.I can't go on...@> - help2("One of your faux pas seems to have wounded me deeply...",@/ - "in fact, I'm barely conscious. Please fix it and try again."); - } -succumb; -} - -@ Users occasionally want to interrupt \TeX\ while it's running. -If the \PASCAL\ runtime system allows this, one can implement -a routine that sets the global variable |interrupt| to some nonzero value -when such an interrupt is signalled. Otherwise there is probably at least -a way to make |interrupt| nonzero using the \PASCAL\ debugger. -@^system dependencies@> -@^debugging@> - -@d check_interrupt {@+if (interrupt!=0) pause_for_instructions(); - } - -@<Global...@>= -static int @!interrupt; /*should \TeX\ pause for instructions?*/ -static bool @!OK_to_interrupt; /*should interrupts be observed?*/ - -@ @<Set init...@>= -interrupt=0;OK_to_interrupt=true; - -@ When an interrupt has been detected, the program goes into its -highest interaction level and lets the user have nearly the full flexibility of -the |error| routine. \TeX\ checks for interrupts only at times when it is -safe to do this. - -@p static void pause_for_instructions(void) -{@+if (OK_to_interrupt) - {@+interaction=error_stop_mode; - if ((selector==log_only)||(selector==no_print)) - incr(selector); - print_err("Interruption"); -@.Interruption@> - help3("You rang?",@/ - "Try to insert an instruction for me (e.g., `I\\showlists'),",@/ - "unless you just want to quit by typing `X'."); - deletions_allowed=false;error();deletions_allowed=true; - interrupt=0; - } -} - -@* Arithmetic with scaled dimensions. -The principal computations performed by \TeX\ are done entirely in terms of -integers less than $2^{31}$ in magnitude; and divisions are done only when both -dividend and divisor are nonnegative. Thus, the arithmetic specified in this -program can be carried out in exactly the same way on a wide variety of -computers, including some small ones. Why? Because the arithmetic -calculations need to be spelled out precisely in order to guarantee that -\TeX\ will produce identical output on different machines. If some -quantities were rounded differently in different implementations, we would -find that line breaks and even page breaks might occur in different places. -Hence the arithmetic of \TeX\ has been designed with care, and systems that -claim to be implementations of \TeX82 should follow precisely the -@:TeX82}{\TeX82@> -calculations as they appear in the present program. - -(Actually there are three places where \TeX\ uses |/| with a possibly negative -numerator. These are harmless; see |/| in the index. Also if the user -sets the \.{\\time} or the \.{\\year} to a negative value, some diagnostic -information will involve negative-numerator division. The same remarks -apply for |%| as well as for |/|.) - -@ Here is a routine that calculates half of an integer, using an -unambiguous convention with respect to signed odd numbers. - -@p static int half(int @!x) -{@+if (odd(x)) return(x+1)/2; -else return x/2; -} - -@ Fixed-point arithmetic is done on {\sl scaled integers\/} that are multiples -of $2^{-16}$. In other words, a binary point is assumed to be sixteen bit -positions from the right end of a binary computer word. - -@d unity 0200000 /*$2^{16}$, represents 1.00000*/ -@d two 0400000 /*$2^{17}$, represents 2.00000*/ - -@<Types...@>= -typedef int scaled; /*this type is used for scaled integers*/ -typedef int32_t nonnegative_integer; /*$0\le x<2^{31}$*/ -typedef int8_t small_number; /*this type is self-explanatory*/ - -@ The following function is used to create a scaled integer from a given decimal -fraction $(.d_0d_1\ldots d_{k-1})$, where |0 <= k <= 17|. The digit $d_i$ is -given in |dig[i]|, and the calculation produces a correctly rounded result. - -@p static scaled round_decimals(small_number @!k) - /*converts a decimal fraction*/ -{@+int a; /*the accumulator*/ -a=0; -while (k > 0) - {@+decr(k);a=(a+dig[k]*two)/10; - } -return(a+1)/2; -} - -@ Conversely, here is a procedure analogous to |print_int|. If the output -of this procedure is subsequently read by \TeX\ and converted by the -|round_decimals| routine above, it turns out that the original value will -be reproduced exactly; the ``simplest'' such decimal number is output, -but there is always at least one digit following the decimal point. - -The invariant relation in the \&{repeat} loop is that a sequence of -decimal digits yet to be printed will yield the original number if and only if -they form a fraction~$f$ in the range $s-\delta\le 10\cdot2^{16}f<s$. -We can stop if and only if $f=0$ satisfies this condition; the loop will -terminate before $s$ can possibly become zero. - -@p void print_scaled(scaled @!s) /*prints scaled real, rounded to five - digits*/ -{@+scaled delta; /*amount of allowable inaccuracy*/ -if (s < 0) - {@+print_char('-');negate(s); /*print the sign, if negative*/ - } -print_int(s/unity); /*print the integer part*/ -print_char('.'); -s=10*(s%unity)+5;delta=10; -@/do@+{if (delta > unity) s=s+0100000-50000; /*round the last digit*/ -print_char('0'+(s/unity));s=10*(s%unity);delta=delta*10; -}@+ while (!(s <= delta)); -} - -@ Physical sizes that a \TeX\ user specifies for portions of documents are -represented internally as scaled points. Thus, if we define an `sp' (scaled -@^sp@> -point) as a unit equal to $2^{-16}$ printer's points, every dimension -inside of \TeX\ is an integer number of sp. There are exactly -4,736,286.72 sp per inch. Users are not allowed to specify dimensions -larger than $2^{30}-1$ sp, which is a distance of about 18.892 feet (5.7583 -meters); two such quantities can be added without overflow on a 32-bit -computer. - -The present implementation of \TeX\ does not check for overflow when -@^overflow in arithmetic@> -dimensions are added or subtracted. This could be done by inserting a -few dozen tests of the form `\ignorespaces|if (x >= 010000000000)| -\\{report\_overflow}', but the chance of overflow is so remote that -such tests do not seem worthwhile. - -\TeX\ needs to do only a few arithmetic operations on scaled quantities, -other than addition and subtraction, and the following subroutines do most of -the work. A single computation might use several subroutine calls, and it is -desirable to avoid producing multiple error messages in case of arithmetic -overflow; so the routines set the global variable |arith_error| to |true| -instead of reporting errors directly to the user. Another global variable, -|rem|, holds the remainder after a division. - -@<Glob...@>= -static bool @!arith_error; /*has arithmetic overflow occurred recently?*/ -static scaled @!rem; /*amount subtracted to get an exact division*/ - -@ The first arithmetical subroutine we need computes $nx+y$, where |x| -and~|y| are |scaled| and |n| is an integer. We will also use it to -multiply integers. - -@d nx_plus_y(A, B, C) mult_and_add(A, B, C, 07777777777) -@d mult_integers(A, B) mult_and_add(A, B, 0, 017777777777) - -@p static scaled mult_and_add(int @!n, scaled @!x, scaled @!y, scaled @!max_answer) -{@+if (n < 0) - {@+negate(x);negate(n); - } -if (n==0) return y; -else if (((x <= (max_answer-y)/n)&&(-x <= (max_answer+y)/n))) - return n*x+y; -else{@+arith_error=true;return 0; - } -} - -@ We also need to divide scaled dimensions by integers. - -@p static scaled x_over_n(scaled @!x, int @!n) -{@+bool negative; /*should |rem| be negated?*/ -scaled x_over_n; -negative=false; -if (n==0) - {@+arith_error=true;x_over_n=0;rem=x; - } -else{@+if (n < 0) - {@+negate(x);negate(n);negative=true; - } - if (x >= 0) - {@+x_over_n=x/n;rem=x%n; - } - else{@+x_over_n=-((-x)/n);rem=-((-x)%n); - } - } -if (negative) negate(rem); -return x_over_n;} - -@ Then comes the multiplication of a scaled number by a fraction |n/(double)d|, -where |n| and |d| are nonnegative integers | <= @t$2^{16}$@>| and |d| is -positive. It would be too dangerous to multiply by~|n| and then divide -by~|d|, in separate operations, since overflow might well occur; and it -would be too inaccurate to divide by |d| and then multiply by |n|. Hence -this subroutine simulates 1.5-precision arithmetic. - -@p static scaled xn_over_d(scaled @!x, int @!n, int @!d) -{@+bool positive; /*was |x >= 0|?*/ -nonnegative_integer @!t, @!u, @!v; /*intermediate quantities*/ -scaled xn_over_d; -if (x >= 0) positive=true; -else{@+negate(x);positive=false; - } -t=(x%0100000)*n; -u=(x/0100000)*n+(t/0100000); -v=(u%d)*0100000+(t%0100000); -if (u/d >= 0100000) arith_error=true; -else u=0100000*(u/d)+(v/d); -if (positive) - {@+xn_over_d=u;rem=v%d; - } -else{@+xn_over_d=-u;rem=-(v%d); - } -return xn_over_d;} - -@ The next subroutine is used to compute the ``badness'' of glue, when a -total~|t| is supposed to be made from amounts that sum to~|s|. According -to {\sl The \TeX book}, the badness of this situation is $100(t/s)^3$; -however, badness is simply a heuristic, so we need not squeeze out the -last drop of accuracy when computing it. All we really want is an -approximation that has similar properties. -@:TeXbook}{\sl The \TeX book@> - -The actual method used to compute the badness is easier to read from the -program than to describe in words. It produces an integer value that is a -reasonably close approximation to $100(t/s)^3$, and all implementations -of \TeX\ should use precisely this method. Any badness of $2^{13}$ or more is -treated as infinitely bad, and represented by 10000. - -It is not difficult to prove that $$\hbox{|badness(t+1, s) >= badness(t, s) - >= badness(t, s+1)|}.$$ The badness function defined here is capable of -computing at most 1095 distinct values, but that is plenty. - -@d inf_bad 10000 /*infinitely bad value*/ - -@p halfword badness(scaled @!t, scaled @!s) /*compute badness, given |t >= 0|*/ -{@+int r; /*approximation to $\alpha t/s$, where $\alpha^3\approx - 100\cdot2^{18}$*/ -if (t==0) return 0; -else if (s <= 0) return inf_bad; -else{@+if (t <= 7230584) r=(t*297)/s; /*$297^3=99.94\times2^{18}$*/ - else if (s >= 1663497) r=t/(s/297); - else r=t; - if (r > 1290) return inf_bad; /*$1290^3<2^{31}<1291^3$*/ - else return(r*r*r+0400000)/01000000; - } /*that was $r^3/2^{18}$, rounded to the nearest integer*/ -} - -@ When \TeX\ ``packages'' a list into a box, it needs to calculate the -proportionality ratio by which the glue inside the box should stretch -or shrink. This calculation does not affect \TeX's decision making, -so the precise details of rounding, etc., in the glue calculation are not -of critical importance for the consistency of results on different computers. - -We shall use the type |glue_ratio| for such proportionality ratios. -A glue ratio should take the same amount of memory as an -|int| (usually 32 bits) if it is to blend smoothly with \TeX's -other data structures. Thus |glue_ratio| should be equivalent to -|short_real| in some implementations of \PASCAL. Alternatively, -it is possible to deal with glue ratios using nothing but fixed-point -arithmetic; see {\sl TUGboat \bf3},1 (March 1982), 10--27. (But the -routines cited there must be modified to allow negative glue ratios.) -@^system dependencies@> - -@d set_glue_ratio_zero(A) A=0.0 /*store the representation of zero ratio*/ -@d set_glue_ratio_one(A) A=1.0 /*store the representation of unit ratio*/ -@d float(A) ((double)(A)) /*convert from |glue_ratio| to type |double|*/ -@d unfloat(A) ((glue_ratio)(A)) /*convert from |double| to type |glue_ratio|*/ -@d float_constant(A) ((double)(A)) /*convert |int| constant to |double|*/ - -@<Types...@>= -#if __SIZEOF_FLOAT__==4 -typedef float float32_t; -#else -#error float type must have size 4 -#endif -typedef float @!glue_ratio; /*one-word representation of a glue expansion factor*/ - -@* Packed data. -In order to make efficient use of storage space, \TeX\ bases its major data -structures on a |memory_word|, which contains either a (signed) integer, -possibly scaled, or a (signed) |glue_ratio|, or a small number of -fields that are one half or one quarter of the size used for storing -integers. - -If |x| is a variable of type |memory_word|, it contains up to four -fields that can be referred to as follows: -$$\vbox{\halign{\hfil#&#\hfil&#\hfil\cr -|x|&.|i|&(an |int|)\cr -|x|&.|sc|\qquad&(a |scaled| integer)\cr -|x|&.|gr|&(a |glue_ratio|)\cr -|x.hh.lh|, |x.hh|&.|rh|&(two halfword fields)\cr -|x.hh.b0|, |x.hh.b1|, |x.hh|&.|rh|&(two quarterword fields, one halfword - field)\cr -|x.qqqq.b0|, |x.qqqq.b1|, |x.qqqq|&.|b2|, |x.qqqq.b3|\hskip-100pt - &\qquad\qquad\qquad(four quarterword fields)\cr}}$$ -This is somewhat cumbersome to write, and not very readable either, but -macros will be used to make the notation shorter and more transparent. -The \PASCAL\ code below gives a formal definition of |memory_word| and -its subsidiary types, using packed variant records. \TeX\ makes no -assumptions about the relative positions of the fields within a word. - -Since we are assuming 32-bit integers, a halfword must contain at least -16 bits, and a quarterword must contain at least 8 bits. -@^system dependencies@> -But it doesn't hurt to have more bits; for example, with enough 36-bit -words you might be able to have |mem_max| as large as 262142, which is -eight times as much memory as anybody had during the first four years of -\TeX's existence. - -N.B.: Valuable memory space will be dreadfully wasted unless \TeX\ is compiled -by a \PASCAL\ that packs all of the |memory_word| variants into -the space of a single integer. This means, for example, that |glue_ratio| -words should be |short_real| instead of |double| on some computers. Some -\PASCAL\ compilers will pack an integer whose subrange is `|0 dotdot 255|' into -an eight-bit field, but others insist on allocating space for an additional -sign bit; on such systems you can get 256 values into a quarterword only -if the subrange is `|-128 dotdot 127|'. - -The present implementation tries to accommodate as many variations as possible, -so it makes few assumptions. If integers having the subrange -`|min_quarterword dotdot max_quarterword|' can be packed into a quarterword, -and if integers having the subrange `|min_halfword dotdot max_halfword|' -can be packed into a halfword, everything should work satisfactorily. - -It is usually most efficient to have |min_quarterword==min_halfword==0|, -so one should try to achieve this unless it causes a severe problem. -The values defined here are recommended for most 32-bit computers. - -@d min_quarterword 0 /*smallest allowable value in a |quarterword|*/ -@d max_quarterword 65535 /*largest allowable value in a |quarterword|*/ -@d min_halfword 0 /*smallest allowable value in a |halfword|*/ -@d max_halfword 0x3FFFFFFF /*largest allowable value in a |halfword|*/ - -@ Here are the inequalities that the quarterword and halfword values -must satisfy (or rather, the inequalities that they mustn't satisfy): - -@<Check the ``constant''...@>= -#ifdef @!INIT -if ((mem_min!=mem_bot)||(mem_max!=mem_top)) bad=10; -#endif -@;@/ -if ((mem_min > mem_bot)||(mem_max < mem_top)) bad=10; -if ((min_quarterword > 0)||(max_quarterword < 127)) bad=11; -if ((min_halfword > 0)||(max_halfword < 32767)) bad=12; -if ((min_quarterword < min_halfword)||@| - (max_quarterword > max_halfword)) bad=13; -if ((mem_min < min_halfword)||(mem_max >= max_halfword)||@| - (mem_bot-mem_min > max_halfword+1)) bad=14; -if ((font_base < min_quarterword)||(font_max > max_quarterword)) bad=15; -if (font_max > font_base+256) bad=16; -if ((save_size > max_halfword)||(max_strings > max_halfword)) bad=17; -if (buf_size > max_halfword) bad=18; -if (max_quarterword-min_quarterword < 255) bad=19; - -@ The operation of adding or subtracting |min_quarterword| occurs quite -frequently in \TeX, so it is convenient to abbreviate this operation -by using the macros |qi| and |qo| for input and output to and from -quarterword format. - -The inner loop of \TeX\ will run faster with respect to compilers -that don't optimize expressions like `|x+0|' and `|x-0|', if these -macros are simplified in the obvious way when |min_quarterword==0|. -@^inner loop@>@^system dependencies@> - -@d qi(A) A+min_quarterword - /*to put an |eight_bits| item into a quarterword*/ -@d qo(A) A-min_quarterword - /*to take an |eight_bits| item out of a quarterword*/ -@d hi(A) A+min_halfword - /*to put a sixteen-bit item into a halfword*/ -@d ho(A) A-min_halfword - /*to take a sixteen-bit item from a halfword*/ - -@ The reader should study the following definitions closely: -@^system dependencies@> - -@d sc i /*|scaled| data is equivalent to |int|*/ - -@<Types...@>= -typedef uint16_t quarterword; /*1/4 of a word*/ -typedef int32_t halfword; /*1/2 of a word*/ -typedef int8_t two_choices; /*used when there are two variants in a record*/ -typedef int8_t four_choices; /*used when there are four variants in a record*/ -typedef struct { @;@/ - halfword @!rh; - union { - halfword @!lh; - struct { quarterword @!b0;quarterword @!b1;} ; - };} two_halves; -typedef struct { @;@/ - quarterword @!b0; - quarterword @!b1; - quarterword @!b2; - quarterword @!b3; - } four_quarters; -typedef struct { @;@/ - union { - int @!i; - glue_ratio @!gr; - two_halves @!hh; - four_quarters @!qqqq; - };} memory_word; -typedef struct {@+FILE *f;@+memory_word@,d;@+} word_file; - -@ When debugging, we may want to print a |memory_word| without knowing -what type it is; so we print it in all modes. -@^dirty \PASCAL@>@^debugging@> - -@p -#ifdef @!DEBUG -static void print_word(memory_word @!w) - /*prints |w| in all ways*/ -{@+print_int(w.i);print_char(' ');@/ -print_scaled(w.sc);print_char(' ');@/ -print_scaled(round(unity*float(w.gr)));print_ln();@/ -@^real multiplication@> -print_int(w.hh.lh);print_char('=');print_int(w.hh.b0);print_char(':'); -print_int(w.hh.b1);print_char(';');print_int(w.hh.rh);print_char(' ');@/ -print_int(w.qqqq.b0);print_char(':');print_int(w.qqqq.b1);print_char(':'); -print_int(w.qqqq.b2);print_char(':');print_int(w.qqqq.b3); -} -#endif - -@* Dynamic memory allocation. -The \TeX\ system does nearly all of its own memory allocation, so that it -can readily be transported into environments that do not have automatic -facilities for strings, garbage collection, etc., and so that it can be in -control of what error messages the user receives. The dynamic storage -requirements of \TeX\ are handled by providing a large array |mem| in -which consecutive blocks of words are used as nodes by the \TeX\ routines. - -Pointer variables are indices into this array, or into another array -called |eqtb| that will be explained later. A pointer variable might -also be a special flag that lies outside the bounds of |mem|, so we -allow pointers to assume any |halfword| value. The minimum halfword -value represents a null pointer. \TeX\ does not assume that |mem[null]| exists. - -@s pointer int -@d pointer halfword /*a flag or a location in |mem| or |eqtb|*/ -@d null min_halfword /*the null pointer*/ - -@<Glob...@>= -static pointer @!temp_ptr; /*a pointer variable for occasional emergency use*/ - -@ The |mem| array is divided into two regions that are allocated separately, -but the dividing line between these two regions is not fixed; they grow -together until finding their ``natural'' size in a particular job. -Locations less than or equal to |lo_mem_max| are used for storing -variable-length records consisting of two or more words each. This region -is maintained using an algorithm similar to the one described in exercise -2.5--19 of {\sl The Art of Computer Programming}. However, no size field -appears in the allocated nodes; the program is responsible for knowing the -relevant size when a node is freed. Locations greater than or equal to -|hi_mem_min| are used for storing one-word records; a conventional -\.{AVAIL} stack is used for allocation in this region. - -Locations of |mem| between |mem_bot| and |mem_top| may be dumped as part -of preloaded format files, by the \.{INITEX} preprocessor. -@.INITEX@> -Production versions of \TeX\ may extend the memory at both ends in order to -provide more space; locations between |mem_min| and |mem_bot| are always -used for variable-size nodes, and locations between |mem_top| and |mem_max| -are always used for single-word nodes. - -The key pointers that govern |mem| allocation have a prescribed order: -$$\advance\thickmuskip-2mu -\hbox{|null <= mem_min <= mem_bot < lo_mem_max < - hi_mem_min < mem_top <= mem_end <= mem_max|.}$$ - -Empirical tests show that the present implementation of \TeX\ tends to -spend about 9\pct! of its running time allocating nodes, and about 6\pct! -deallocating them after their use. - -@<Glob...@>= -memory_word @!mem0[mem_max-mem_min+1], *const @!mem = @!mem0-mem_min; /*the big dynamic storage area*/ -static pointer @!lo_mem_max; /*the largest location of variable-size memory in use*/ -pointer @!hi_mem_min; /*the smallest location of one-word memory in use*/ - -@ In order to study the memory requirements of particular applications, it -is possible to prepare a version of \TeX\ that keeps track of current and -maximum memory usage. When code between the delimiters | -#ifdef @!STAT -| $\ldots$ -|tats| is not ``commented out,'' \TeX\ will run a bit slower but it will -report these statistics when |tracing_stats| is sufficiently large. - -@<Glob...@>= -int @!var_used, @!dyn_used; /*how much memory is in use*/ -#ifdef @!STAT -#define incr_dyn_used @[incr(dyn_used)@] -#define decr_dyn_used @[decr(dyn_used)@] -#else -#define incr_dyn_used -#define decr_dyn_used -#endif - -@ Let's consider the one-word memory region first, since it's the -simplest. The pointer variable |mem_end| holds the highest-numbered location -of |mem| that has ever been used. The free locations of |mem| that -occur between |hi_mem_min| and |mem_end|, inclusive, are of type -|two_halves|, and we write |info(p)| and |link(p)| for the |lh| -and |rh| fields of |mem[p]| when it is of this type. The single-word -free locations form a linked list -$$|avail|,\;\hbox{|link(avail)|},\;\hbox{|link(link(avail))|},\;\ldots$$ -terminated by |null|. - -@d link(A) mem[A].hh.rh /*the |link| field of a memory word*/ -@d info(A) mem[A].hh.lh /*the |info| field of a memory word*/ - -@<Glob...@>= -static pointer @!avail; /*head of the list of available one-word nodes*/ -static pointer @!mem_end; /*the last one-word node used in |mem|*/ - -@ If memory is exhausted, it might mean that the user has forgotten -a right brace. We will define some procedures later that try to help -pinpoint the trouble. - -@p @<Declare the procedure called |show_token_list|@>@/ -@<Declare the procedure called |runaway|@>@; - -@ The function |get_avail| returns a pointer to a new one-word node whose -|link| field is null. However, \TeX\ will halt if there is no more room left. -@^inner loop@> - -If the available-space list is empty, i.e., if |avail==null|, -we try first to increase |mem_end|. If that cannot be done, i.e., if -|mem_end==mem_max|, we try to decrease |hi_mem_min|. If that cannot be -done, i.e., if |hi_mem_min==lo_mem_max+1|, we have to quit. - -@p static pointer get_avail(void) /*single-word node allocation*/ -{@+pointer p; /*the new node being got*/ -p=avail; /*get top location in the |avail| stack*/ -if (p!=null) avail=link(avail); /*and pop it off*/ -else if (mem_end < mem_max) /*or go into virgin territory*/ - {@+incr(mem_end);p=mem_end; - } -else{@+decr(hi_mem_min);p=hi_mem_min; - if (hi_mem_min <= lo_mem_max) - {@+runaway(); /*if memory is exhausted, display possible runaway text*/ - overflow("main memory size", mem_max+1-mem_min); - /*quit; all one-word nodes are busy*/ -@:TeX capacity exceeded main memory size}{\quad main memory size@> - } - } -link(p)=null; /*provide an oft-desired initialization of the new node*/ -#ifdef @!STAT -incr(dyn_used); -#endif -@; /*maintain statistics*/ -return p; -} - -@ Conversely, a one-word node is recycled by calling |free_avail|. -This routine is part of \TeX's ``inner loop,'' so we want it to be fast. -@^inner loop@> - -@d free_avail(A) /*single-word node liberation*/ - {@+link(A)=avail;avail=A; - decr_dyn_used; - } - -@ There's also a |fast_get_avail| routine, which saves the procedure-call -overhead at the expense of extra programming. This routine is used in -the places that would otherwise account for the most calls of |get_avail|. -@^inner loop@> - -@d fast_get_avail(A) @t@>@;@/ - {@+A=avail; /*avoid |get_avail| if possible, to save time*/ - if (A==null) A=get_avail(); - else{@+avail=link(A);link(A)=null; - incr_dyn_used; - } - } - -@ The procedure |flush_list(p)| frees an entire linked list of -one-word nodes that starts at position |p|. -@^inner loop@> - -@p static void flush_list(pointer @!p) /*makes list of single-word nodes - available*/ -{@+pointer @!q, @!r; /*list traversers*/ -if (p!=null) - {@+r=p; - @/do@+{q=r;r=link(r); -#ifdef @!STAT -decr(dyn_used); -#endif - }@+ while (!(r==null)); /*now |q| is the last node on the list*/ - link(q)=avail;avail=p; - } -} - -@ The available-space list that keeps track of the variable-size portion -of |mem| is a nonempty, doubly-linked circular list of empty nodes, -pointed to by the roving pointer |rover|. - -Each empty node has size 2 or more; the first word contains the special -value |max_halfword| in its |link| field and the size in its |info| field; -the second word contains the two pointers for double linking. - -Each nonempty node also has size 2 or more. Its first word is of type -|two_halves|\kern-1pt, and its |link| field is never equal to |max_halfword|. -Otherwise there is complete flexibility with respect to the contents -of its other fields and its other words. - -(We require |mem_max < max_halfword| because terrible things can happen -when |max_halfword| appears in the |link| field of a nonempty node.) - -@d empty_flag max_halfword /*the |link| of an empty variable-size node*/ -@d is_empty(A) (link(A)==empty_flag) /*tests for empty node*/ -@d node_size(A) info(A) /*the size field in empty variable-size nodes*/ -@d llink(A) info(A+1) /*left link in doubly-linked list of empty nodes*/ -@d rlink(A) link(A+1) /*right link in doubly-linked list of empty nodes*/ - -@<Glob...@>= -static pointer @!rover; /*points to some node in the list of empties*/ - -@ A call to |get_node| with argument |s| returns a pointer to a new node -of size~|s|, which must be 2~or more. The |link| field of the first word -of this new node is set to null. An overflow stop occurs if no suitable -space exists. - -If |get_node| is called with $s=2^{30}$, it simply merges adjacent free -areas and returns the value |max_halfword|. - -@p pointer get_node(int @!s) /*variable-size node allocation*/ -{@+ -pointer p; /*the node currently under inspection*/ -pointer @!q; /*the node physically after node |p|*/ -int @!r; /*the newly allocated node, or a candidate for this honor*/ -int @!t; /*temporary register*/ -restart: p=rover; /*start at some free node in the ring*/ -@/do@+{@<Try to allocate within node |p| and its physical successors, and |goto found| -if allocation was possible@>; -@^inner loop@> -p=rlink(p); /*move to the next node in the ring*/ -}@+ while (!(p==rover)); /*repeat until the whole list has been traversed*/ -if (s==010000000000) - {@+return max_halfword; - } -if (lo_mem_max+2 < hi_mem_min) if (lo_mem_max+2 <= mem_bot+max_halfword) - @<Grow more variable-size memory and |goto restart|@>; -overflow("main memory size", mem_max+1-mem_min); - /*sorry, nothing satisfactory is left*/ -@:TeX capacity exceeded main memory size}{\quad main memory size@> -found: link(r)=null; /*this node is now nonempty*/ -#ifdef @!STAT -var_used=var_used+s; /*maintain usage statistics*/ -#endif -@;@/ -return r; -} - -@ The lower part of |mem| grows by 1000 words at a time, unless -we are very close to going under. When it grows, we simply link -a new node into the available-space list. This method of controlled -growth helps to keep the |mem| usage consecutive when \TeX\ is -implemented on ``virtual memory'' systems. -@^virtual memory@> - -@<Grow more variable-size memory and |goto restart|@>= -{@+if (hi_mem_min-lo_mem_max >= 1998) t=lo_mem_max+1000; -else t=lo_mem_max+1+(hi_mem_min-lo_mem_max)/2; - /*|lo_mem_max+2 <= t < hi_mem_min|*/ -p=llink(rover);q=lo_mem_max;rlink(p)=q;llink(rover)=q;@/ -if (t > mem_bot+max_halfword) t=mem_bot+max_halfword; -rlink(q)=rover;llink(q)=p;link(q)=empty_flag;node_size(q)=t-lo_mem_max;@/ -lo_mem_max=t;link(lo_mem_max)=null;info(lo_mem_max)=null; -rover=q;goto restart; -} - -@ Empirical tests show that the routine in this section performs a -node-merging operation about 0.75 times per allocation, on the average, -after which it finds that |r > p+1| about 95\pct! of the time. - -@<Try to allocate...@>= -q=p+node_size(p); /*find the physical successor*/ -@^inner loop@> -while (is_empty(q)) /*merge node |p| with node |q|*/ - {@+t=rlink(q); - if (q==rover) rover=t; - llink(t)=llink(q);rlink(llink(q))=t;@/ - q=q+node_size(q); - } -r=q-s; -if (r > p+1) @<Allocate from the top of node |p| and |goto found|@>; -if (r==p) if (rlink(p)!=p) - @<Allocate entire node |p| and |goto found|@>; -node_size(p)=q-p /*reset the size in case it grew*/ - -@ @<Allocate from the top...@>= -{@+node_size(p)=r-p; /*store the remaining size*/ -@^inner loop@> -rover=p; /*start searching here next time*/ -goto found; -} - -@ Here we delete node |p| from the ring, and let |rover| rove around. - -@<Allocate entire...@>= -{@+rover=rlink(p);t=llink(p); -llink(rover)=t;rlink(t)=rover; -goto found; -} - -@ Conversely, when some variable-size node |p| of size |s| is no longer needed, -the operation |free_node(p, s)| will make its words available, by inserting -|p| as a new empty node just before where |rover| now points. -@^inner loop@> - -@p void free_node(pointer @!p, halfword @!s) /*variable-size node - liberation*/ -{@+pointer q; /*|llink(rover)|*/ -node_size(p)=s;link(p)=empty_flag; -q=llink(rover);llink(p)=q;rlink(p)=rover; /*set both links*/ -llink(rover)=p;rlink(q)=p; /*insert |p| into the ring*/ -#ifdef @!STAT -var_used=var_used-s; -#endif -@; /*maintain statistics*/ -} - -@ Just before \.{INITEX} writes out the memory, it sorts the doubly linked -available space list. The list is probably very short at such times, so a -simple insertion sort is used. The smallest available location will be -pointed to by |rover|, the next-smallest by |rlink(rover)|, etc. - -@p -#ifdef @!INIT -static void sort_avail(void) /*sorts the available variable-size nodes - by location*/ -{@+pointer p, @!q, @!r; /*indices into |mem|*/ -pointer @!old_rover; /*initial |rover| setting*/ -p=get_node(010000000000); /*merge adjacent free areas*/ -p=rlink(rover);rlink(rover)=max_halfword;old_rover=rover; -while (p!=old_rover) @<Sort \(p)|p| into the list starting at |rover| and advance -|p| to |rlink(p)|@>; -p=rover; -while (rlink(p)!=max_halfword) - {@+llink(rlink(p))=p;p=rlink(p); - } -rlink(p)=rover;llink(rover)=p; -} -#endif - -@ The following |while | loop is guaranteed to -terminate, since the list that starts at -|rover| ends with |max_halfword| during the sorting procedure. - -@<Sort \(p)|p|...@>= -if (p < rover) - {@+q=p;p=rlink(q);rlink(q)=rover;rover=q; - } -else{@+q=rover; - while (rlink(q) < p) q=rlink(q); - r=rlink(p);rlink(p)=rlink(q);rlink(q)=p;p=r; - } - -@* Data structures for boxes and their friends. -From the computer's standpoint, \TeX's chief mission is to create -horizontal and vertical lists. We shall now investigate how the elements -of these lists are represented internally as nodes in the dynamic memory. - -A horizontal or vertical list is linked together by |link| fields in -the first word of each node. Individual nodes represent boxes, glue, -penalties, or special things like discretionary hyphens; because of this -variety, some nodes are longer than others, and we must distinguish different -kinds of nodes. We do this by putting a `|type|' field in the first word, -together with the link and an optional `|subtype|'. - -@d type(A) mem[A].hh.b0 /*identifies what kind of node this is*/ -@d subtype(A) mem[A].hh.b1 /*secondary identification in some cases*/ - -@ A |@!char_node|, which represents a single character, is the most important -kind of node because it accounts for the vast majority of all boxes. -Special precautions are therefore taken to ensure that a |char_node| does -not take up much memory space. Every such node is one word long, and in fact -it is identifiable by this property, since other kinds of nodes have at least -two words, and they appear in |mem| locations less than |hi_mem_min|. -This makes it possible to omit the |type| field in a |char_node|, leaving -us room for two bytes that identify a |font| and a |character| within -that font. - -Note that the format of a |char_node| allows for up to 256 different -fonts and up to 256 characters per font; but most implementations will -probably limit the total number of fonts to fewer than 75 per job, -and most fonts will stick to characters whose codes are -less than 128 (since higher codes -are more difficult to access on most keyboards). - -Extensions of \TeX\ intended for oriental languages will need even more -than $256\times256$ possible characters, when we consider different sizes -@^oriental characters@>@^Chinese characters@>@^Japanese characters@> -and styles of type. It is suggested that Chinese and Japanese fonts be -handled by representing such characters in two consecutive |char_node| -entries: The first of these has |font==font_base|, and its |link| points -to the second; -the second identifies the font and the character dimensions. -The saving feature about oriental characters is that most of them have -the same box dimensions. The |character| field of the first |char_node| -is a ``\\{charext}'' that distinguishes between graphic symbols whose -dimensions are identical for typesetting purposes. (See the \MF\ manual.) -Such an extension of \TeX\ would not be difficult; further details are -left to the reader. - -In order to make sure that the |character| code fits in a quarterword, -\TeX\ adds the quantity |min_quarterword| to the actual code. - -Character nodes appear only in horizontal lists, never in vertical lists. - -@d is_char_node(A) (A >= hi_mem_min) - /*does the argument point to a |char_node|?*/ -@d font(A) type(A) /*the font code in a |char_node|*/ -@d character(A) subtype(A) /*the character code in a |char_node|*/ - -@ An |hlist_node| stands for a box that was made from a horizontal list. -Each |hlist_node| is seven words long, and contains the following fields -(in addition to the mandatory |type| and |link|, which we shall not -mention explicitly when discussing the other node types): The |height| and -|width| and |depth| are scaled integers denoting the dimensions of the -box. There is also a |shift_amount| field, a scaled integer indicating -how much this box should be lowered (if it appears in a horizontal list), -or how much it should be moved to the right (if it appears in a vertical -list). There is a |list_ptr| field, which points to the beginning of the -list from which this box was fabricated; if |list_ptr| is |null|, the box -is empty. Finally, there are three fields that represent the setting of -the glue: |glue_set(p)| is a word of type |glue_ratio| that represents -the proportionality constant for glue setting; |glue_sign(p)| is -|stretching| or |shrinking| or |normal| depending on whether or not the -glue should stretch or shrink or remain rigid; and |glue_order(p)| -specifies the order of infinity to which glue setting applies (|normal|, -|fil|, |fill|, or |filll|). The |subtype| field is not used. - -@d hlist_node 0 /*|type| of hlist nodes*/ -@d box_node_size 9 /*number of words to allocate for a box, set, or pack node*/ -@d width_offset 1 /*position of |width| field in a box node*/ -@d depth_offset 2 /*position of |depth| field in a box node*/ -@d height_offset 3 /*position of |height| field in a box node*/ -@d width(A) mem[A+width_offset].sc /*width of the box, in sp*/ -@d depth(A) mem[A+depth_offset].sc /*depth of the box, in sp*/ -@d height(A) mem[A+height_offset].sc /*height of the box, in sp*/ -@d shift_amount(A) mem[A+4].sc /*repositioning distance, in sp*/ -@d list_offset 5 /*position of |list_ptr| field in a box node*/ -@d list_ptr(A) link(A+list_offset) /*beginning of the list inside the box*/ -@d glue_order(A) subtype(A+list_offset) /*applicable order of infinity*/ -@d glue_sign(A) type(A+list_offset) /*stretching or shrinking*/ -@d normal 0 /*the most common case when several cases are named*/ -@d stretching 1 /*glue setting applies to the stretch components*/ -@d shrinking 2 /*glue setting applies to the shrink components*/ -@d glue_offset 6 /*position of |glue_set| in a box node*/ -@d glue_set(A) mem[A+glue_offset].gr - /*a word of type |glue_ratio| for glue setting*/ - -@ The |new_null_box| function returns a pointer to an |hlist_node| in -which all subfields have the values corresponding to `\.{\\hbox\{\}}'. -(The |subtype| field is set to |min_quarterword|, for historic reasons -that are no longer relevant.) - -@p pointer new_null_box(void) /*creates a new box node*/ -{@+pointer p; /*the new node*/ -p=get_node(box_node_size);type(p)=hlist_node; -subtype(p)=min_quarterword; -width(p)=0;depth(p)=0;height(p)=0;shift_amount(p)=0;list_ptr(p)=null; -glue_sign(p)=normal;glue_order(p)=normal;set_glue_ratio_zero(glue_set(p)); -return p; -} - -@ A |vlist_node| is like an |hlist_node| in all respects except that it -contains a vertical list. - -@d vlist_node 1 /*|type| of vlist nodes*/ - -@ A |rule_node| stands for a solid black rectangle; it has |width|, -|depth|, and |height| fields just as in an |hlist_node|. However, if -any of these dimensions is $-2^{30}$, the actual value will be determined -by running the rule up to the boundary of the innermost enclosing box. -This is called a ``running dimension.'' The |width| is never running in -an hlist; the |height| and |depth| are never running in a~vlist. - -@d rule_node 2 /*|type| of rule nodes*/ -@d rule_node_size 4 /*number of words to allocate for a rule node*/ -@d null_flag -010000000000 /*$-2^{30}$, signifies a missing item*/ -@d is_running(A) (A==null_flag) /*tests for a running dimension*/ - -@ A new rule node is delivered by the |new_rule| function. It -makes all the dimensions ``running,'' so you have to change the -ones that are not allowed to run. - -@p pointer new_rule(void) -{@+pointer p; /*the new node*/ -p=get_node(rule_node_size);type(p)=rule_node; -subtype(p)=0; /*the |subtype| is not used*/ -width(p)=null_flag;depth(p)=null_flag;height(p)=null_flag; -return p; -} - -@ Insertions are represented by |ins_node| records, where the |subtype| -indicates the corresponding box number. For example, `\.{\\insert 250}' -leads to an |ins_node| whose |subtype| is |250+min_quarterword|. -The |height| field of an |ins_node| is slightly misnamed; it actually holds -the natural height plus depth of the vertical list being inserted. -The |depth| field holds the |split_max_depth| to be used in case this -insertion is split, and the |split_top_ptr| points to the corresponding -|split_top_skip|. The |float_cost| field holds the |floating_penalty| that -will be used if this insertion floats to a subsequent page after a -split insertion of the same class. There is one more field, the -|ins_ptr|, which points to the beginning of the vlist for the insertion. - -@d ins_node 3 /*|type| of insertion nodes*/ -@d ins_node_size 5 /*number of words to allocate for an insertion*/ -@d float_cost(A) mem[A+1].i /*the |floating_penalty| to be used*/ -@d ins_ptr(A) info(A+4) /*the vertical list to be inserted*/ -@d split_top_ptr(A) link(A+4) /*the |split_top_skip| to be used*/ - -@ A |mark_node| has a |mark_ptr| field that points to the reference count -of a token list that contains the user's \.{\\mark} text. -This field occupies a full word instead of a halfword, because -there's nothing to put in the other halfword; it is easier in \PASCAL\ to -use the full word than to risk leaving garbage in the unused half. - -@d mark_node 4 /*|type| of a mark node*/ -@d small_node_size 2 /*number of words to allocate for most node types*/ -@d mark_ptr(A) mem[A+1].i /*head of the token list for a mark*/ - -@ An |adjust_node|, which occurs only in horizontal lists, -specifies material that will be moved out into the surrounding -vertical list; i.e., it is used to implement \TeX's `\.{\\vadjust}' -operation. The |adjust_ptr| field points to the vlist containing this -material. - -@d adjust_node 5 /*|type| of an adjust node*/ -@d adjust_ptr(A) mark_ptr(A) /*vertical list to be moved out of horizontal list*/ - -@ A |ligature_node|, which occurs only in horizontal lists, specifies -a character that was fabricated from the interaction of two or more -actual characters. The second word of the node, which is called the -|lig_char| word, contains |font| and |character| fields just as in a -|char_node|. The characters that generated the ligature have not been -forgotten, since they are needed for diagnostic messages and for -hyphenation; the |lig_ptr| field points to a linked list of character -nodes for all original characters that have been deleted. (This list -might be empty if the characters that generated the ligature were -retained in other nodes.) - -The |subtype| field is 0, plus 2 and/or 1 if the original source of the -ligature included implicit left and/or right boundaries. - -@d ligature_node 6 /*|type| of a ligature node*/ -@d lig_char(A) A+1 /*the word where the ligature is to be found*/ -@d lig_ptr(A) link(lig_char(A)) /*the list of characters*/ - -@ The |new_ligature| function creates a ligature node having given -contents of the |font|, |character|, and |lig_ptr| fields. We also have -a |new_lig_item| function, which returns a two-word node having a given -|character| field. Such nodes are used for temporary processing as ligatures -are being created. - -@p static pointer new_ligature(quarterword @!f, quarterword @!c, pointer @!q) -{@+pointer p; /*the new node*/ -p=get_node(small_node_size);type(p)=ligature_node; -font(lig_char(p))=f;character(lig_char(p))=c;lig_ptr(p)=q; -subtype(p)=0;return p; -} -@# -static pointer new_lig_item(quarterword @!c) -{@+pointer p; /*the new node*/ -p=get_node(small_node_size);character(p)=c;lig_ptr(p)=null; -return p; -} - -@ A |disc_node|, which occurs only in horizontal lists, specifies a -``dis\-cretion\-ary'' line break. If such a break occurs at node |p|, the text -that starts at |pre_break(p)| will precede the break, the text that starts at -|post_break(p)| will follow the break, and text that appears in the next -|replace_count(p)| nodes will be ignored. For example, an ordinary -discretionary hyphen, indicated by `\.{\\-}', yields a |disc_node| with -|pre_break| pointing to a |char_node| containing a hyphen, |post_break==null|, -and |replace_count==0|. All three of the discretionary texts must be -lists that consist entirely of character, kern, box, rule, and ligature nodes. - -If |pre_break(p)==null|, the |ex_hyphen_penalty| will be charged for this -break. Otherwise the |hyphen_penalty| will be charged. The texts will -actually be substituted into the list by the line-breaking algorithm if it -decides to make the break, and the discretionary node will disappear at -that time; thus, the output routine sees only discretionaries that were -not chosen. - -@d disc_node 7 /*|type| of a discretionary node*/ -@d replace_count(A) (subtype(A)&0x7F) /*how many subsequent nodes to replace*/ -@d set_replace_count(A,B) (subtype(A)=(B)&0x7F) -@d set_auto_disc(A) (subtype(A)|=0x80) -@d is_auto_disc(A) (subtype(A)&0x80) -@d pre_break(A) llink(A) /*text that precedes a discretionary break*/ -@d post_break(A) rlink(A) /*text that follows a discretionary break*/ - -@p pointer new_disc(void) /*creates an empty |disc_node|*/ -{@+pointer p; /*the new node*/ -p=get_node(small_node_size);type(p)=disc_node; -set_replace_count(p,0);pre_break(p)=null;post_break(p)=null; -return p; -} - -@ A |whatsit_node| is a wild card reserved for extensions to \TeX. The -|subtype| field in its first word says what `\\{whatsit}' it is, and -implicitly determines the node size (which must be 2 or more) and the -format of the remaining words. When a |whatsit_node| is encountered -in a list, special actions are invoked; knowledgeable people who are -careful not to mess up the rest of \TeX\ are able to make \TeX\ do new -things by adding code at the end of the program. For example, there -might be a `\TeX nicolor' extension to specify different colors of ink, -@^extensions to \TeX@> -and the whatsit node might contain the desired parameters. - -The present implementation of \TeX\ treats the features associated with -`\.{\\write}' and `\.{\\special}' as if they were extensions, in order to -illustrate how such routines might be coded. We shall defer further -discussion of extensions until the end of this program. - -@d whatsit_node 8 /*|type| of special extension nodes*/ - -@ A |math_node|, which occurs only in horizontal lists, appears before and -after mathematical formulas. The |subtype| field is |before| before the -formula and |after| after it. There is a |width| field, which represents -the amount of surrounding space inserted by \.{\\mathsurround}. - -@d math_node 9 /*|type| of a math node*/ -@d before 0 /*|subtype| for math node that introduces a formula*/ -@d after 1 /*|subtype| for math node that winds up a formula*/ - -@p static pointer new_math(scaled @!w, small_number @!s) -{@+pointer p; /*the new node*/ -p=get_node(small_node_size);type(p)=math_node; -subtype(p)=s;width(p)=w;return p; -} - -@ \TeX\ makes use of the fact that |hlist_node|, |vlist_node|, -|rule_node|, |ins_node|, |mark_node|, |adjust_node|, |ligature_node|, -|disc_node|, |whatsit_node|, and |math_node| are at the low end of the -type codes, by permitting a break at glue in a list if and only if the -|type| of the previous node is less than |math_node|. Furthermore, a -node is discarded after a break if its type is |math_node| or~more. - -@d precedes_break(A) (type(A) < math_node) -@d non_discardable(A) (type(A) < math_node) - -@ A |glue_node| represents glue in a list. However, it is really only -a pointer to a separate glue specification, since \TeX\ makes use of the -fact that many essentially identical nodes of glue are usually present. -If |p| points to a |glue_node|, |glue_ptr(p)| points to -another packet of words that specify the stretch and shrink components, etc. - -Glue nodes also serve to represent leaders; the |subtype| is used to -distinguish between ordinary glue (which is called |normal|) and the three -kinds of leaders (which are called |a_leaders|, |c_leaders|, and |x_leaders|). -The |leader_ptr| field points to a rule node or to a box node containing the -leaders; it is set to |null| in ordinary glue nodes. - -Many kinds of glue are computed from \TeX's ``skip'' parameters, and -it is helpful to know which parameter has led to a particular glue node. -Therefore the |subtype| is set to indicate the source of glue, whenever -it originated as a parameter. We will be defining symbolic names for the -parameter numbers later (e.g., |line_skip_code==0|, |baseline_skip_code==1|, -etc.); it suffices for now to say that the |subtype| of parametric glue -will be the same as the parameter number, plus~one. - -In math formulas there are two more possibilities for the |subtype| in a -glue node: |mu_glue| denotes an \.{\\mskip} (where the units are scaled \.{mu} -instead of scaled \.{pt}); and |cond_math_glue| denotes the `\.{\\nonscript}' -feature that cancels the glue node immediately following if it appears -in a subscript. - -@d glue_node 10 /*|type| of node that points to a glue specification*/ -@d cond_math_glue 98 /*special |subtype| to suppress glue in the next node*/ -@d mu_glue 99 /*|subtype| for math glue*/ -@d a_leaders 100 /*|subtype| for aligned leaders*/ -@d c_leaders 101 /*|subtype| for centered leaders*/ -@d x_leaders 102 /*|subtype| for expanded leaders*/ -@d glue_ptr(A) llink(A) /*pointer to a glue specification*/ -@d leader_ptr(A) rlink(A) /*pointer to box or rule node for leaders*/ - -@ A glue specification has a halfword reference count in its first word, -@^reference counts@> -representing |null| plus the number of glue nodes that point to it (less one). -Note that the reference count appears in the same position as -the |link| field in list nodes; this is the field that is initialized -to |null| when a node is allocated, and it is also the field that is flagged -by |empty_flag| in empty nodes. - -Glue specifications also contain three |scaled| fields, for the |width|, -|stretch|, and |shrink| dimensions. Finally, there are two one-byte -fields called |stretch_order| and |shrink_order|; these contain the -orders of infinity (|normal|, |fil|, |fill|, or |filll|) -corresponding to the stretch and shrink values. - -@d glue_spec_size 4 /*number of words to allocate for a glue specification*/ -@d glue_ref_count(A) link(A) /*reference count of a glue specification*/ -@d stretch(A) mem[A+2].sc /*the stretchability of this glob of glue*/ -@d shrink(A) mem[A+3].sc /*the shrinkability of this glob of glue*/ -@d stretch_order(A) type(A) /*order of infinity for stretching*/ -@d shrink_order(A) subtype(A) /*order of infinity for shrinking*/ -@d fil 1 /*first-order infinity*/ -@d fill 2 /*second-order infinity*/ -@d filll 3 /*third-order infinity*/ - -@<Types...@>= -typedef int8_t glue_ord; /*infinity to the 0, 1, 2, or 3 power*/ - -@ Here is a function that returns a pointer to a copy of a glue spec. -The reference count in the copy is |null|, because there is assumed -to be exactly one reference to the new specification. - -@p pointer new_spec(pointer @!p) /*duplicates a glue specification*/ -{@+pointer q; /*the new spec*/ -q=get_node(glue_spec_size);@/ -mem[q]=mem[p];glue_ref_count(q)=null;@/ -width(q)=width(p);stretch(q)=stretch(p);shrink(q)=shrink(p); -return q; -} - -@ And here's a function that creates a glue node for a given parameter -identified by its code number; for example, -|new_param_glue(line_skip_code)| returns a pointer to a glue node for the -current \.{\\lineskip}. - -@p pointer new_param_glue(small_number @!n) -{@+pointer p; /*the new node*/ -pointer @!q; /*the glue specification*/ -p=get_node(small_node_size);type(p)=glue_node;subtype(p)=n+1; -leader_ptr(p)=null;@/ -q=@<Current |mem| equivalent of glue parameter number |n|@>@t@>; -glue_ptr(p)=q;incr(glue_ref_count(q)); -return p; -} - -@ Glue nodes that are more or less anonymous are created by |new_glue|, -whose argument points to a glue specification. - -@p pointer new_glue(pointer @!q) -{@+pointer p; /*the new node*/ -p=get_node(small_node_size);type(p)=glue_node;subtype(p)=normal; -leader_ptr(p)=null;glue_ptr(p)=q;incr(glue_ref_count(q)); -return p; -} - -@ Still another subroutine is needed: This one is sort of a combination -of |new_param_glue| and |new_glue|. It creates a glue node for one of -the current glue parameters, but it makes a fresh copy of the glue -specification, since that specification will probably be subject to change, -while the parameter will stay put. The global variable |temp_ptr| is -set to the address of the new spec. - -@p static pointer new_skip_param(small_number @!n) -{@+pointer p; /*the new node*/ -temp_ptr=new_spec(@<Current |mem| equivalent of glue parameter...@>); -p=new_glue(temp_ptr);glue_ref_count(temp_ptr)=null;subtype(p)=n+1; -return p; -} - -@ A |kern_node| has a |width| field to specify a (normally negative) -amount of spacing. This spacing correction appears in horizontal lists -between letters like A and V when the font designer said that it looks -better to move them closer together or further apart. A kern node can -also appear in a vertical list, when its `|width|' denotes additional -spacing in the vertical direction. The |subtype| is either |normal| (for -kerns inserted from font information or math mode calculations) or |explicit| -(for kerns inserted from \.{\\kern} and \.{\\/} commands) or |acc_kern| -(for kerns inserted from non-math accents) or |mu_glue| (for kerns -inserted from \.{\\mkern} specifications in math formulas). - -@d kern_node 11 /*|type| of a kern node*/ -@d explicit 1 /*|subtype| of kern nodes from \.{\\kern} and \.{\\/}*/ -@d acc_kern 2 /*|subtype| of kern nodes from accents*/ - -@ The |new_kern| function creates a kern node having a given width. - -@p static pointer new_kern(scaled @!w) -{@+pointer p; /*the new node*/ -p=get_node(small_node_size);type(p)=kern_node; -subtype(p)=normal; -width(p)=w; -return p; -} - -@ A |penalty_node| specifies the penalty associated with line or page -breaking, in its |penalty| field. This field is a fullword integer, but -the full range of integer values is not used: Any penalty | >= 10000| is -treated as infinity, and no break will be allowed for such high values. -Similarly, any penalty | <= -10000| is treated as negative infinity, and a -break will be forced. - -@d penalty_node 12 /*|type| of a penalty node*/ -@d inf_penalty inf_bad /*``infinite'' penalty value*/ -@d eject_penalty (-inf_penalty) /*``negatively infinite'' penalty value*/ -@d penalty(A) mem[A+1].i /*the added cost of breaking a list here*/ - -@ Anyone who has been reading the last few sections of the program will -be able to guess what comes next. - -@p pointer new_penalty(int @!m) -{@+pointer p; /*the new node*/ -p=get_node(small_node_size);type(p)=penalty_node; -subtype(p)=0; /*the |subtype| is not used*/ -penalty(p)=m;return p; -} - -@ You might think that we have introduced enough node types by now. Well, -almost, but there is one more: An |unset_node| has nearly the same format -as an |hlist_node| or |vlist_node|; it is used for entries in \.{\\halign} -or \.{\\valign} that are not yet in their final form, since the box -dimensions are their ``natural'' sizes before any glue adjustment has been -made. The |glue_set| word is not present; instead, we have a |glue_stretch| -field, which contains the total stretch of order |glue_order| that is -present in the hlist or vlist being boxed. -Similarly, the |shift_amount| field is replaced by a |glue_shrink| field, -containing the total shrink of order |glue_sign| that is present. -The |subtype| field is called |span_count|; an unset box typically -contains the data for |qo(span_count)+1| columns. -Unset nodes will be changed to box nodes when alignment is completed. - -@d unset_node 13 /*|type| for an unset node*/ -@d unset_set_node 32 /*|type| for an unset |set_node|*/ -@d unset_pack_node 33 /*|type| for an unset |pack_node|*/ -@d glue_stretch(A) mem[A+glue_offset].sc /*total stretch in an unset node*/ -@d glue_shrink(A) shift_amount(A) /*total shrink in an unset node*/ -@d span_count(A) subtype(A) /*indicates the number of spanned columns*/ - -@ In fact, there are still more types coming. When we get to math formula -processing we will see that a |style_node| has |type==14|; and a number -of larger type codes will also be defined, for use in math mode only. - -@ Warning: If any changes are made to these data structure layouts, such as -changing any of the node sizes or even reordering the words of nodes, -the |copy_node_list| procedure and the memory initialization code -below may have to be changed. Such potentially dangerous parts of the -program are listed in the index under `data structure assumptions'. -@!@^data structure assumptions@> -However, other references to the nodes are made symbolically in terms of -the \.{WEB} macro definitions above, so that format changes will leave -\TeX's other algorithms intact. -@^system dependencies@> - -@* Memory layout. -Some areas of |mem| are dedicated to fixed usage, since static allocation is -more efficient than dynamic allocation when we can get away with it. For -example, locations |mem_bot| to |mem_bot+3| are always used to store the -specification for glue that is `\.{0pt plus 0pt minus 0pt}'. The -following macro definitions accomplish the static allocation by giving -symbolic names to the fixed positions. Static variable-size nodes appear -in locations |mem_bot| through |lo_mem_stat_max|, and static single-word nodes -appear in locations |hi_mem_stat_min| through |mem_top|, inclusive. It is -harmless to let |lig_trick| and |garbage| share the same location of |mem|. - -@d zero_glue mem_bot /*specification for \.{0pt plus 0pt minus 0pt}*/ -@d fil_glue zero_glue+glue_spec_size /*\.{0pt plus 1fil minus 0pt}*/ -@d fill_glue fil_glue+glue_spec_size /*\.{0pt plus 1fill minus 0pt}*/ -@d ss_glue fill_glue+glue_spec_size /*\.{0pt plus 1fil minus 1fil}*/ -@d fil_neg_glue ss_glue+glue_spec_size /*\.{0pt plus -1fil minus 0pt}*/ -@d lo_mem_stat_max fil_neg_glue+glue_spec_size-1 /*largest statically - allocated word in the variable-size |mem|*/ -@# -@d page_ins_head mem_top /*list of insertion data for current page*/ -@d contrib_head mem_top-1 /*vlist of items not yet on current page*/ -@d page_head mem_top-2 /*vlist for current page*/ -@d temp_head mem_top-3 /*head of a temporary list of some kind*/ -@d hold_head mem_top-4 /*head of a temporary list of another kind*/ -@d adjust_head mem_top-5 /*head of adjustment list returned by |hpack|*/ -@d active mem_top-7 /*head of active list in |line_break|, needs two words*/ -@d align_head mem_top-8 /*head of preamble list for alignments*/ -@d end_span mem_top-9 /*tail of spanned-width lists*/ -@d omit_template mem_top-10 /*a constant token list*/ -@d null_list mem_top-11 /*permanently empty list*/ -@d lig_trick mem_top-12 /*a ligature masquerading as a |char_node|*/ -@d garbage mem_top-12 /*used for scrap information*/ -@d backup_head mem_top-13 /*head of token list built by |scan_keyword|*/ -@d setpage_head mem_top-14 /*head of page template list build by |new_setpage_node|*/ -@d max_page type(setpage_head) /* maximum page template number */ -@d max_stream subtype(setpage_head) /* maximum stream number */ -@d hi_mem_stat_min mem_top-14 /*smallest statically allocated word in - the one-word |mem|*/ -@d hi_mem_stat_usage 15 /*the number of one-word nodes always present*/ - -@ The following code gets |mem| off to a good start, when \TeX\ is -initializing itself the slow~way. - -@<Local variables for init...@>= -int @!k; /*index into |mem|, |eqtb|, etc.*/ - -@ @<Initialize table entries...@>= -for (k=mem_bot+1; k<=lo_mem_stat_max; k++) mem[k].sc=0; - /*all glue dimensions are zeroed*/ -@^data structure assumptions@> -k=mem_bot;@+while (k <= lo_mem_stat_max) - /*set first words of glue specifications*/ - {@+glue_ref_count(k)=null+1; - stretch_order(k)=normal;shrink_order(k)=normal; - k=k+glue_spec_size; - } -stretch(fil_glue)=unity;stretch_order(fil_glue)=fil;@/ -stretch(fill_glue)=unity;stretch_order(fill_glue)=fill;@/ -stretch(ss_glue)=unity;stretch_order(ss_glue)=fil;@/ -shrink(ss_glue)=unity;shrink_order(ss_glue)=fil;@/ -stretch(fil_neg_glue)=-unity;stretch_order(fil_neg_glue)=fil;@/ -rover=lo_mem_stat_max+1; -link(rover)=empty_flag; /*now initialize the dynamic memory*/ -node_size(rover)=1000; /*which is a 1000-word available node*/ -llink(rover)=rover;rlink(rover)=rover;@/ -lo_mem_max=rover+1000;link(lo_mem_max)=null;info(lo_mem_max)=null;@/ -for (k=hi_mem_stat_min; k<=mem_top; k++) - mem[k]=mem[lo_mem_max]; /*clear list heads*/ -@<Initialize the special list heads and constant nodes@>; -avail=null;mem_end=mem_top; -hi_mem_min=hi_mem_stat_min; /*initialize the one-word memory*/ -var_used=lo_mem_stat_max+1-mem_bot;dyn_used=hi_mem_stat_usage; - /*initialize statistics*/ - -@ If \TeX\ is extended improperly, the |mem| array might get screwed up. -For example, some pointers might be wrong, or some ``dead'' nodes might not -have been freed when the last reference to them disappeared. Procedures -|check_mem| and |search_mem| are available to help diagnose such -problems. These procedures make use of two arrays called |is_free| and -|was_free| that are present only if \TeX's debugging routines have -been included. (You may want to decrease the size of |mem| while you -@^debugging@> -are debugging.) - -@<Glob...@>= -#ifdef @!DEBUG -static bool @!is_free0[mem_max-mem_min+1], *const @!is_free = @!is_free0-mem_min; /*free cells*/ -@t\hskip10pt@>static bool @!was_free0[mem_max-mem_min+1], *const @!was_free = @!was_free0-mem_min; - /*previously free cells*/ -@t\hskip10pt@>static pointer @!was_mem_end, @!was_lo_max, @!was_hi_min; - /*previous |mem_end|, |lo_mem_max|, and |hi_mem_min|*/ -@t\hskip10pt@>static bool @!panicking; /*do we want to check memory constantly?*/ -#endif - -@ @<Set initial...@>= -#ifdef @!DEBUG -was_mem_end=mem_min; /*indicate that everything was previously free*/ -was_lo_max=mem_min;was_hi_min=mem_max; -panicking=false; -#endif - -@ Procedure |check_mem| makes sure that the available space lists of -|mem| are well formed, and it optionally prints out all locations -that are reserved now but were free the last time this procedure was called. - -@p -#ifdef @!DEBUG -static void check_mem(bool @!print_locs) -{@+ /*loop exits*/ -int p, @!q; /*current locations of interest in |mem|*/ -bool @!clobbered; /*is something amiss?*/ -for (p=mem_min; p<=lo_mem_max; p++) is_free[p]=false; /*you can probably - do this faster*/ -for (p=hi_mem_min; p<=mem_end; p++) is_free[p]=false; /*ditto*/ -@<Check single-word |avail| list@>; -@<Check variable-size |avail| list@>; -@<Check flags of unavailable nodes@>; -if (print_locs) @<Print newly busy locations@>; -for (p=mem_min; p<=lo_mem_max; p++) was_free[p]=is_free[p]; -for (p=hi_mem_min; p<=mem_end; p++) was_free[p]=is_free[p]; - /*|was_free=is_free| might be faster*/ -was_mem_end=mem_end;was_lo_max=lo_mem_max;was_hi_min=hi_mem_min; -} -#endif - -@ @<Check single-word...@>= -p=avail;q=null;clobbered=false; -while (p!=null) - {@+if ((p > mem_end)||(p < hi_mem_min)) clobbered=true; - else if (is_free[p]) clobbered=true; - if (clobbered) - {@+print_nl("AVAIL list clobbered at "); -@.AVAIL list clobbered...@> - print_int(q);goto done1; - } - is_free[p]=true;q=p;p=link(q); - } -done1: - -@ @<Check variable-size...@>= -p=rover;q=null;clobbered=false; -@/do@+{if ((p >= lo_mem_max)||(p < mem_min)) clobbered=true; - else if ((rlink(p) >= lo_mem_max)||(rlink(p) < mem_min)) clobbered=true; - else if (!(is_empty(p))||(node_size(p) < 2)||@| - (p+node_size(p) > lo_mem_max)||@|(llink(rlink(p))!=p)) clobbered=true; - if (clobbered) - {@+print_nl("Double-AVAIL list clobbered at "); - print_int(q);goto done2; - } -for (q=p; q<=p+node_size(p)-1; q++) /*mark all locations free*/ - {@+if (is_free[q]) - {@+print_nl("Doubly free location at "); -@.Doubly free location...@> - print_int(q);goto done2; - } - is_free[q]=true; - } -q=p;p=rlink(p); -}@+ while (!(p==rover)); -done2: - -@ @<Check flags...@>= -p=mem_min; -while (p <= lo_mem_max) /*node |p| should not be empty*/ - {@+if (is_empty(p)) - {@+print_nl("Bad flag at ");print_int(p); -@.Bad flag...@> - } - while ((p <= lo_mem_max)&&!is_free[p]) incr(p); - while ((p <= lo_mem_max)&&is_free[p]) incr(p); - } - -@ @<Print newly busy...@>= -{@+print_nl("New busy locs:"); -for (p=mem_min; p<=lo_mem_max; p++) - if (!is_free[p]&&((p > was_lo_max)||was_free[p])) - {@+print_char(' ');print_int(p); - } -for (p=hi_mem_min; p<=mem_end; p++) - if (!is_free[p]&& - ((p < was_hi_min)||(p > was_mem_end)||was_free[p])) - {@+print_char(' ');print_int(p); - } -} - -@ The |search_mem| procedure attempts to answer the question ``Who points -to node~|p|?'' In doing so, it fetches |link| and |info| fields of |mem| -that might not be of type |two_halves|. Strictly speaking, this is -@^dirty \PASCAL@> -undefined in \PASCAL, and it can lead to ``false drops'' (words that seem to -point to |p| purely by coincidence). But for debugging purposes, we want -to rule out the places that do {\sl not\/} point to |p|, so a few false -drops are tolerable. - -@p -#ifdef @!DEBUG -static void search_mem(pointer @!p) /*look for pointers to |p|*/ -{@+int q; /*current position being searched*/ -for (q=mem_min; q<=lo_mem_max; q++) - {@+if (link(q)==p) - {@+print_nl("LINK(");print_int(q);print_char(')'); - } - if (info(q)==p) - {@+print_nl("INFO(");print_int(q);print_char(')'); - } - } -for (q=hi_mem_min; q<=mem_end; q++) - {@+if (link(q)==p) - {@+print_nl("LINK(");print_int(q);print_char(')'); - } - if (info(q)==p) - {@+print_nl("INFO(");print_int(q);print_char(')'); - } - } -@<Search |eqtb| for equivalents equal to |p|@>; -@<Search |save_stack| for equivalents that point to |p|@>; -@<Search |hyph_list| for pointers to |p|@>; -} -#endif - -@* Displaying boxes. -We can reinforce our knowledge of the data structures just introduced -by considering two procedures that display a list in symbolic form. -The first of these, called |short_display|, is used in ``overfull box'' -messages to give the top-level description of a list. The other one, -called |show_node_list|, prints a detailed description of exactly what -is in the data structure. - -The philosophy of |short_display| is to ignore the fine points about exactly -what is inside boxes, except that ligatures and discretionary breaks are -expanded. As a result, |short_display| is a recursive procedure, but the -recursion is never more than one level deep. -@^recursion@> - -A global variable |font_in_short_display| keeps track of the font code that -is assumed to be present when |short_display| begins; deviations from this -font will be printed. - -@<Glob...@>= -int @!font_in_short_display; /*an internal font number*/ - -@ Boxes, rules, inserts, whatsits, marks, and things in general that are -sort of ``complicated'' are indicated only by printing `\.{[]}'. - -@p void short_display(int @!p) /*prints highlights of list |p|*/ -{@+int n; /*for replacement counts*/ -while (p > mem_min) - {@+if (is_char_node(p)) - {@+if (p <= mem_end) - {@+if (font(p)!=font_in_short_display) - {@+if ((font(p) < font_base)||(font(p) > font_max)) - print_char('*'); -@.*\relax@> - else@<Print the font identifier for |font(p)|@>; - print_char(' ');font_in_short_display=font(p); - } - print_ASCII(qo(character(p))); - } - } - else@<Print a short indication of the contents of node |p|@>; - p=link(p); - } -} - -@ @<Print a short indication of the contents of node |p|@>= -switch (type(p)) { -case hlist_node: case vlist_node: case ins_node: case whatsit_node: case mark_node: case adjust_node: - case unset_node: case unset_set_node: case unset_pack_node: print("[]");@+break; -case rule_node: print_char('|');@+break; -case glue_node: if (glue_ptr(p)!=zero_glue) print_char(' ');@+break; -case math_node: print_char('$');@+break; -case ligature_node: short_display(lig_ptr(p));@+break; -case disc_node: {@+short_display(pre_break(p)); - short_display(post_break(p));@/ - n=replace_count(p); - while (n > 0) - {@+if (link(p)!=null) p=link(p); - decr(n); - } - } @+break; -default:do_nothing; -} - -@ The |show_node_list| routine requires some auxiliary subroutines: one to -print a font-and-character combination, one to print a token list without -its reference count, and one to print a rule dimension. - -@p static void print_font_and_char(int @!p) /*prints |char_node| data*/ -{@+if (p > mem_end) print_esc("CLOBBERED."); -else{@+if ((font(p) < font_base)||(font(p) > font_max)) print_char('*'); -@.*\relax@> - else@<Print the font identifier for |font(p)|@>; - print_char(' ');print_ASCII(qo(character(p))); - } -} -@# -static void print_mark(int @!p) /*prints token list data in braces*/ -{@+print_char('{'); -if ((p < hi_mem_min)||(p > mem_end)) print_esc("CLOBBERED."); -else show_token_list(link(p), null, max_print_line-10); -print_char('}'); -} -@# -static void print_rule_dimen(scaled @!d) /*prints dimension in rule node*/ -{@+if (is_running(d)) print_char('*');else print_scaled(d); -@.*\relax@> -} - -@ Then there is a subroutine that prints glue stretch and shrink, possibly -followed by the name of finite units: - -@p static void print_glue(scaled @!d, int @!order, char *@!s) - /*prints a glue component*/ -{@+print_scaled(d); -if ((order < normal)||(order > filll)) print("foul"); -else if (order > normal) - {@+print("fil"); - while (order > fil) - {@+print_char('l');decr(order); - } - } -else if (s!=0) print(s); -} - -@ The next subroutine prints a whole glue specification. - -@p void print_spec(int @!p, char *@!s) - /*prints a glue specification*/ -{@+if ((p < mem_min)||(p >= lo_mem_max)) print_char('*'); -@.*\relax@> -else{@+print_scaled(width(p)); - if (s!=0) print(s); - if (stretch(p)!=0) - {@+print(" plus ");print_glue(stretch(p), stretch_order(p), s); - } - if (shrink(p)!=0) - {@+print(" minus ");print_glue(shrink(p), shrink_order(p), s); - } - } -} - -@ We also need to declare some procedures that appear later in this -documentation. - -@p @<Declare procedures needed for displaying the elements of mlists@>@; -@<Declare the procedure called |print_skip_param|@>@; -static void print_xdimen(pointer p) -{ print_scaled(xdimen_width(p)); - if (xdimen_hfactor(p)!=0) - { print_char('+');print_scaled(xdimen_hfactor(p));print("*hsize");} - if (xdimen_vfactor(p)!=0) - { print_char('+');print_scaled(xdimen_vfactor(p));print("*vsize");} -} -extern void print_baseline_skip(int i); - -@ Since boxes can be inside of boxes, |show_node_list| is inherently recursive, -@^recursion@> -up to a given maximum number of levels. The history of nesting is indicated -by the current string, which will be printed at the beginning of each line; -the length of this string, namely |cur_length|, is the depth of nesting. - -Recursive calls on |show_node_list| therefore use the following pattern: - -@d node_list_display(A) - {@+append_char('.');show_node_list(A);flush_char; - } /*|str_room| need not be checked; see |show_box| below*/ - -@ A global variable called |depth_threshold| is used to record the maximum -depth of nesting for which |show_node_list| will show information. If we -have |depth_threshold==0|, for example, only the top level information will -be given and no sublists will be traversed. Another global variable, called -|breadth_max|, tells the maximum number of items to show at each level; -|breadth_max| had better be positive, or you won't see anything. - -@<Glob...@>= -int @!depth_threshold; /*maximum nesting depth in box displays*/ -int @!breadth_max; /*maximum number of items shown at the same list level*/ - -@ Now we are ready for |show_node_list| itself. This procedure has been -written to be ``extra robust'' in the sense that it should not crash or get -into a loop even if the data structures have been messed up by bugs in -the rest of the program. You can safely call its parent routine -|show_box(p)| for arbitrary values of |p| when you are debugging \TeX. -However, in the presence of bad data, the procedure may -@^dirty \PASCAL@>@^debugging@> -fetch a |memory_word| whose variant is different from the way it was stored; -for example, it might try to read |mem[p].hh| when |mem[p]| -contains a scaled integer, if |p| is a pointer that has been -clobbered or chosen at random. - -@p void show_node_list(int @!p) /*prints a node list symbolically*/ -{@+ -int n; /*the number of items already printed at this level*/ -double @!g; /*a glue ratio, as a floating point number*/ -if (cur_length > depth_threshold) - {@+if (p > null) print(" []"); - /*indicate that there's been some truncation*/ - return; - } -n=0; -while (p > mem_min) - {@+print_ln();print_current_string(); /*display the nesting history*/ - if (p > mem_end) /*pointer out of range*/ - {@+print("Bad link, display aborted.");return; -@.Bad link...@> - } - incr(n);if (n > breadth_max) /*time to stop*/ - {@+print("etc.");return; -@.etc@> - } - display_node(p); - p=link(p); - } - -} - -void display_node(pointer p)@t~@> -{ -if (is_char_node(p)) print_font_and_char(p); -else switch (type(p)) { - case hlist_node: case vlist_node: case unset_node: case unset_set_node: case unset_pack_node: @<Display box |p|@>@;@+break; - case rule_node: @<Display rule |p|@>@;@+break; - case ins_node: @<Display insertion |p|@>@;@+break; - case whatsit_node: @<Display the whatsit node |p|@>@;@+break; - case glue_node: @<Display glue |p|@>@;@+break; - case kern_node: @<Display kern |p|@>@;@+break; - case math_node: @<Display math node |p|@>@;@+break; - case ligature_node: @<Display ligature |p|@>@;@+break; - case penalty_node: @<Display penalty |p|@>@;@+break; - case disc_node: @<Display discretionary |p|@>@;@+break; - case mark_node: @<Display mark |p|@>@;@+break; - case adjust_node: @<Display adjustment |p|@>@;@+break; - @t\4@>@<Cases of |show_node_list| that arise in mlists only@>@; - default:print("Unknown node type!"); - } -} - -@ @<Display box |p|@>= -{@+if (type(p)==hlist_node) print_esc("h"); -else if (type(p)==vlist_node) print_esc("v"); -else print_esc("unset"); -print("box(");print_scaled(height(p));print_char('+'); -print_scaled(depth(p));print(")x");print_scaled(width(p)); -if (type(p)==unset_set_node) print("set"); -else if (type(p)==unset_pack_node) print("pack"); -else if (type(p)==unset_node) - @<Display special fields of the unset node |p|@>@; -else{@+@<Display the value of |glue_set(p)|@>; - if (shift_amount(p)!=0) - {@+print(", shifted ");print_scaled(shift_amount(p)); - } - } -node_list_display(list_ptr(p)); /*recursive call*/ -} - -@ @<Display special fields of the unset node |p|@>= -{@+if (span_count(p)!=min_quarterword) - {@+print(" (");print_int(qo(span_count(p))+1); - print(" columns)"); - } -if (glue_stretch(p)!=0) - {@+print(", stretch ");print_glue(glue_stretch(p), glue_order(p), 0); - } -if (glue_shrink(p)!=0) - {@+print(", shrink ");print_glue(glue_shrink(p), glue_sign(p), 0); - } -} - -@ The code will have to change in this place if |glue_ratio| is -a structured type instead of an ordinary |double|. Note that this routine -should avoid arithmetic errors even if the |glue_set| field holds an -arbitrary random value. The following code assumes that a properly -formed nonzero |double| number has absolute value $2^{20}$ or more when -it is regarded as an integer; this precaution was adequate to prevent -floating point underflow on the author's computer. -@^system dependencies@> -@^dirty \PASCAL@> - -@<Display the value of |glue_set(p)|@>= -g=float(glue_set(p)); -if ((g!=float_constant(0))&&(glue_sign(p)!=normal)) - {@+print(", glue set "); - if (glue_sign(p)==shrinking) print("- "); - if (abs(mem[p+glue_offset].i) < 04000000) print("?.?"); - else if (abs(g) > float_constant(20000)) - {@+if (g > float_constant(0)) print_char('>'); - else print("< -"); - print_glue(20000*unity, glue_order(p), 0); - } - else print_glue(round(unity*g), glue_order(p), 0); -@^real multiplication@> - } - -@ @<Display rule |p|@>= -{@+print_esc("rule(");print_rule_dimen(height(p));print_char('+'); -print_rule_dimen(depth(p));print(")x");print_rule_dimen(width(p)); -} - -@ @<Display insertion |p|@>= -{@+print_esc("insert");print_int(qo(subtype(p))); -print("; split(");print_spec(split_top_ptr(p), 0); -print_char(',');print_scaled(depth(p)); -print("); float cost ");print_int(float_cost(p)); -node_list_display(ins_ptr(p)); /*recursive call*/ -} - -@ @<Display glue |p|@>= -if (subtype(p) >= a_leaders) @<Display leaders |p|@>@; -else{@+print_esc("glue"); - if (subtype(p)!=normal) - {@+print_char('('); - if (subtype(p) < cond_math_glue) - print_skip_param(subtype(p)-1); - else if (subtype(p)==cond_math_glue) print_esc("nonscript"); - else print_esc("mskip"); - print_char(')'); - } - if (subtype(p)!=cond_math_glue) - {@+print_char(' '); - if (subtype(p) < cond_math_glue) print_spec(glue_ptr(p), 0); - else print_spec(glue_ptr(p),"mu"); - } - } - -@ @<Display leaders |p|@>= -{@+print_esc(""); -if (subtype(p)==c_leaders) print_char('c'); -else if (subtype(p)==x_leaders) print_char('x'); -print("leaders ");print_spec(glue_ptr(p), 0); -node_list_display(leader_ptr(p)); /*recursive call*/ -} - -@ An ``explicit'' kern value is indicated implicitly by an explicit space. - -@<Display kern |p|@>= -if (subtype(p)!=mu_glue) - {@+print_esc("kern"); - if (subtype(p)!=normal) print_char(' '); - print_scaled(width(p)); - if (subtype(p)==acc_kern) print(" (for accent)"); -@.for accent@> - } -else{@+print_esc("mkern");print_scaled(width(p));print("mu"); - } - -@ @<Display math node |p|@>= -{@+print_esc("math"); -if (subtype(p)==before) print("on"); -else print("off"); -if (width(p)!=0) - {@+print(", surrounded ");print_scaled(width(p)); - } -} - -@ @<Display ligature |p|@>= -{@+print_font_and_char(lig_char(p));print(" (ligature "); -if (subtype(p) > 1) print_char('|'); -font_in_short_display=font(lig_char(p));short_display(lig_ptr(p)); -if (odd(subtype(p))) print_char('|'); -print_char(')'); -} - -@ @<Display penalty |p|@>= -{@+print_esc("penalty ");print_int(penalty(p)); -} - -@ The |post_break| list of a discretionary node is indicated by a prefixed -`\.{\char'174}' instead of the `\..' before the |pre_break| list. - -@<Display discretionary |p|@>= -{@+print_esc("discretionary"); -if (replace_count(p) > 0) - {@+print(" replacing ");print_int(replace_count(p)); - } -node_list_display(pre_break(p)); /*recursive call*/ -append_char('|');show_node_list(post_break(p));flush_char; /*recursive call*/ -} - -@ @<Display mark |p|@>= -{@+print_esc("mark");print_mark(mark_ptr(p)); -} - -@ @<Display adjustment |p|@>= -{@+print_esc("vadjust");node_list_display(adjust_ptr(p)); /*recursive call*/ -} - -@ The recursive machinery is started by calling |show_box|. -@^recursion@> - -@p void show_box(pointer @!p) -{@+@<Assign the values |depth_threshold:=show_box_depth| and |breadth_max:=show_box_breadth|@>; -if (breadth_max <= 0) breadth_max=5; -if (pool_ptr+depth_threshold >= pool_size) - depth_threshold=pool_size-pool_ptr-1; - /*now there's enough room for prefix string*/ -show_node_list(p); /*the show starts at |p|*/ -print_ln(); -} - -@* Destroying boxes. -When we are done with a node list, we are obliged to return it to free -storage, including all of its sublists. The recursive procedure -|flush_node_list| does this for us. - -@ First, however, we shall consider two non-recursive procedures that do -simpler tasks. The first of these, |delete_token_ref|, is called when -a pointer to a token list's reference count is being removed. This means -that the token list should disappear if the reference count was |null|, -otherwise the count should be decreased by one. -@^reference counts@> - -@d token_ref_count(A) info(A) /*reference count preceding a token list*/ - -@p void delete_token_ref(pointer @!p) /*|p| points to the reference count - of a token list that is losing one reference*/ -{@+if (token_ref_count(p)==null) flush_list(p); -else decr(token_ref_count(p)); -} - -@ Similarly, |delete_glue_ref| is called when a pointer to a glue -specification is being withdrawn. -@^reference counts@> -@d fast_delete_glue_ref(A) @t@>@;@/ - {@+if (glue_ref_count(A)==null) free_node(A, glue_spec_size); - else decr(glue_ref_count(A)); - } - -@p void delete_glue_ref(pointer @!p) /*|p| points to a glue specification*/ -fast_delete_glue_ref(p) -void delete_xdimen_ref(pointer @!p) /*|p| points to a xdimen specification*/ -{@+if (xdimen_ref_count(p)==null) free_node(p, xdimen_node_size); - else decr(xdimen_ref_count(p)); -} - -@ Now we are ready to delete any node list, recursively. -In practice, the nodes deleted are usually charnodes (about 2/3 of the time), -and they are glue nodes in about half of the remaining cases. -@^recursion@> - -@p void flush_node_list(pointer @!p) /*erase list of nodes starting at |p|*/ -{@+ /*go here when node |p| has been freed*/ -pointer q; /*successor to node |p|*/ -while (p!=null) -@^inner loop@> - {@+q=link(p); - if (is_char_node(p)) free_avail(p)@; - else{@+switch (type(p)) { - case hlist_node: case vlist_node: case unset_node: case unset_set_node: case unset_pack_node: {@+flush_node_list(list_ptr(p)); - free_node(p, box_node_size);goto done; - } - case rule_node: {@+free_node(p, rule_node_size);goto done; - } - case ins_node: {@+flush_node_list(ins_ptr(p)); - delete_glue_ref(split_top_ptr(p)); - free_node(p, ins_node_size);goto done; - } - case whatsit_node: @<Wipe out the whatsit node |p| and |goto done|@>@; - case glue_node: {@+fast_delete_glue_ref(glue_ptr(p)); - if (leader_ptr(p)!=null) flush_node_list(leader_ptr(p)); - } @+break; - case kern_node: case math_node: case penalty_node: do_nothing;@+break; - case ligature_node: flush_node_list(lig_ptr(p));@+break; - case mark_node: delete_token_ref(mark_ptr(p));@+break; - case disc_node: {@+flush_node_list(pre_break(p)); - flush_node_list(post_break(p)); - } @+break; - case adjust_node: flush_node_list(adjust_ptr(p));@+break; - @t\4@>@<Cases of |flush_node_list| that arise in mlists only@>@; - default:confusion("flushing"); -@:this can't happen flushing}{\quad flushing@> - } @/ - free_node(p, small_node_size); - done: ;} - p=q; - } -} - -@* Copying boxes. -Another recursive operation that acts on boxes is sometimes needed: The -procedure |copy_node_list| returns a pointer to another node list that has -the same structure and meaning as the original. Note that since glue -specifications and token lists have reference counts, we need not make -copies of them. Reference counts can never get too large to fit in a -halfword, since each pointer to a node is in a different memory address, -and the total number of memory addresses fits in a halfword. -@^recursion@> -@^reference counts@> - -(Well, there actually are also references from outside |mem|; if the -|save_stack| is made arbitrarily large, it would theoretically be possible -to break \TeX\ by overflowing a reference count. But who would want to do that?) - -@d add_token_ref(A) incr(token_ref_count(A)) /*new reference to a token list*/ -@d add_glue_ref(A) incr(glue_ref_count(A)) /*new reference to a glue spec*/ -@d add_xdimen_ref(A) incr(xdimen_ref_count(A)) /*new reference to an xdimen*/ - -@ The copying procedure copies words en masse without bothering -to look at their individual fields. If the node format changes---for -example, if the size is altered, or if some link field is moved to another -relative position---then this code may need to be changed too. -@^data structure assumptions@> - -@p pointer copy_node_list(pointer @!p) /*makes a duplicate of the - node list that starts at |p| and returns a pointer to the new list*/ -{@+pointer h; /*temporary head of copied list*/ -pointer @!q; /*previous position in new list*/ -pointer @!r; /*current node being fabricated for new list*/ -int @!words; /*number of words remaining to be copied*/ -h=get_avail();q=h; -while (p!=null) - {@+@<Make a copy of node |p| in node |r|@>; - link(q)=r;q=r;p=link(p); - } -link(q)=null;q=link(h);free_avail(h); -return q; -} - -@ @<Make a copy of node |p|...@>= -words=1; /*this setting occurs in more branches than any other*/ -if (is_char_node(p)) r=get_avail(); -else@<Case statement to copy different types and set |words| to the number of initial -words not yet copied@>; -while (words > 0) - {@+decr(words);mem[r+words]=mem[p+words]; - } - -@ @<Case statement to copy...@>= -switch (type(p)) { -case hlist_node: case vlist_node: case unset_node: case unset_set_node: case unset_pack_node: {@+r=get_node(box_node_size); - mem[r+6]=mem[p+6];mem[r+5]=mem[p+5]; /*copy the last two words*/ - list_ptr(r)=copy_node_list(list_ptr(p)); /*this affects |mem[r+5]|*/ - words=5; - } @+break; -case rule_node: {@+r=get_node(rule_node_size);words=rule_node_size; - } @+break; -case ins_node: {@+r=get_node(ins_node_size);mem[r+4]=mem[p+4]; - add_glue_ref(split_top_ptr(p)); - ins_ptr(r)=copy_node_list(ins_ptr(p)); /*this affects |mem[r+4]|*/ - words=ins_node_size-1; - } @+break; -case whatsit_node: @<Make a partial copy of the whatsit node |p| and make |r| point -to it; set |words| to the number of initial words not yet copied@>@;@+break; -case glue_node: {@+r=get_node(small_node_size);add_glue_ref(glue_ptr(p)); - glue_ptr(r)=glue_ptr(p);leader_ptr(r)=copy_node_list(leader_ptr(p)); - } @+break; -case kern_node: case math_node: case penalty_node: {@+r=get_node(small_node_size); - words=small_node_size; - } @+break; -case ligature_node: {@+r=get_node(small_node_size); - mem[lig_char(r)]=mem[lig_char(p)]; /*copy |font| and |character|*/ - lig_ptr(r)=copy_node_list(lig_ptr(p)); - } @+break; -case disc_node: {@+r=get_node(small_node_size); - pre_break(r)=copy_node_list(pre_break(p)); - post_break(r)=copy_node_list(post_break(p)); - } @+break; -case mark_node: {@+r=get_node(small_node_size);add_token_ref(mark_ptr(p)); - words=small_node_size; - } @+break; -case adjust_node: {@+r=get_node(small_node_size); - adjust_ptr(r)=copy_node_list(adjust_ptr(p)); - } @+break; /*|words==1==small_node_size-1|*/ -default:confusion("copying"); -@:this can't happen copying}{\quad copying@> -} - -@* The command codes. -Before we can go any further, we need to define symbolic names for the internal -code numbers that represent the various commands obeyed by \TeX. These codes -are somewhat arbitrary, but not completely so. For example, the command -codes for character types are fixed by the language, since a user says, -e.g., `\.{\\catcode \`\\\${} = 3}' to make \.{\char'44} a math delimiter, -and the command code |math_shift| is equal to~3. Some other codes have -been made adjacent so that |case| statements in the program need not consider -cases that are widely spaced, or so that |case| statements can be replaced -by |if (| statements. - -At any rate, here is the list, for future reference. First come the -``catcode'' commands, several of which share their numeric codes with -ordinary commands when the catcode cannot emerge from \TeX's scanning routine. - -@d escape 0 /*escape delimiter (called \.\\ in {\sl The \TeX book\/})*/ -@:TeXbook}{\sl The \TeX book@> -@d relax 0 /*do nothing ( \.{\\relax} )*/ -@d left_brace 1 /*beginning of a group ( \.\{ )*/ -@d right_brace 2 /*ending of a group ( \.\} )*/ -@d math_shift 3 /*mathematics shift character ( \.\$ )*/ -@d tab_mark 4 /*alignment delimiter ( \.\&, \.{\\span} )*/ -@d car_ret 5 /*end of line ( |carriage_return|, \.{\\cr}, \.{\\crcr} )*/ -@d out_param 5 /*output a macro parameter*/ -@d mac_param 6 /*macro parameter symbol ( \.\# )*/ -@d sup_mark 7 /*superscript ( \.{\char'136} )*/ -@d sub_mark 8 /*subscript ( \.{\char'137} )*/ -@d ignore 9 /*characters to ignore ( \.{\^\^@@} )*/ -@d endv 9 /*end of \<v_j> list in alignment template*/ -@d spacer 10 /*characters equivalent to blank space ( \.{\ } )*/ -@d letter 11 /*characters regarded as letters ( \.{A..Z}, \.{a..z} )*/ -@d other_char 12 /*none of the special character types*/ -@d active_char 13 /*characters that invoke macros ( \.{\char`\~} )*/ -@d par_end 13 /*end of paragraph ( \.{\\par} )*/ -@d match 13 /*match a macro parameter*/ -@d comment 14 /*characters that introduce comments ( \.\% )*/ -@d end_match 14 /*end of parameters to macro*/ -@d stop 14 /*end of job ( \.{\\end}, \.{\\dump} )*/ -@d invalid_char 15 /*characters that shouldn't appear ( \.{\^\^?} )*/ -@d delim_num 15 /*specify delimiter numerically ( \.{\\delimiter} )*/ -@d max_char_code 15 /*largest catcode for individual characters*/ - -@ Next are the ordinary run-of-the-mill command codes. Codes that are -|min_internal| or more represent internal quantities that might be -expanded by `\.{\\the}'. - -@d char_num 16 /*character specified numerically ( \.{\\char} )*/ -@d math_char_num 17 /*explicit math code ( \.{\\mathchar} )*/ -@d mark 18 /*mark definition ( \.{\\mark} )*/ -@d xray 19 /*peek inside of \TeX\ ( \.{\\show}, \.{\\showbox}, etc.~)*/ -@d make_box 20 /*make a box ( \.{\\box}, \.{\\copy}, \.{\\hbox}, etc.~)*/ -@d hmove 21 /*horizontal motion ( \.{\\moveleft}, \.{\\moveright} )*/ -@d vmove 22 /*vertical motion ( \.{\\raise}, \.{\\lower} )*/ -@d un_hbox 23 /*unglue a box ( \.{\\unhbox}, \.{\\unhcopy} )*/ -@d un_vbox 24 /*unglue a box ( \.{\\unvbox}, \.{\\unvcopy} )*/ -@d remove_item 25 /*nullify last item ( \.{\\unpenalty}, - \.{\\unkern}, \.{\\unskip} )*/ -@d hskip 26 /*horizontal glue ( \.{\\hskip}, \.{\\hfil}, etc.~)*/ -@d vskip 27 /*vertical glue ( \.{\\vskip}, \.{\\vfil}, etc.~)*/ -@d mskip 28 /*math glue ( \.{\\mskip} )*/ -@d kern 29 /*fixed space ( \.{\\kern} )*/ -@d mkern 30 /*math kern ( \.{\\mkern} )*/ -@d leader_ship 31 /*use a box ( \.{\\shipout}, \.{\\leaders}, etc.~)*/ -@d halign 32 /*horizontal table alignment ( \.{\\halign} )*/ -@d valign 33 /*vertical table alignment ( \.{\\valign} )*/ -@d no_align 34 /*temporary escape from alignment ( \.{\\noalign} )*/ -@d vrule 35 /*vertical rule ( \.{\\vrule} )*/ -@d hrule 36 /*horizontal rule ( \.{\\hrule} )*/ -@d insert 37 /*vlist inserted in box ( \.{\\insert} )*/ -@d vadjust 38 /*vlist inserted in enclosing paragraph ( \.{\\vadjust} )*/ -@d ignore_spaces 39 /*gobble |spacer| tokens ( \.{\\ignorespaces} )*/ -@d after_assignment 40 /*save till assignment is done ( \.{\\afterassignment} )*/ -@d after_group 41 /*save till group is done ( \.{\\aftergroup} )*/ -@d break_penalty 42 /*additional badness ( \.{\\penalty} )*/ -@d start_par 43 /*begin paragraph ( \.{\\indent}, \.{\\noindent} )*/ -@d ital_corr 44 /*italic correction ( \.{\\/} )*/ -@d accent 45 /*attach accent in text ( \.{\\accent} )*/ -@d math_accent 46 /*attach accent in math ( \.{\\mathaccent} )*/ -@d discretionary 47 /*discretionary texts ( \.{\\-}, \.{\\discretionary} )*/ -@d eq_no 48 /*equation number ( \.{\\eqno}, \.{\\leqno} )*/ -@d left_right 49 /*variable delimiter ( \.{\\left}, \.{\\right} )*/ - /*( or \.{\\middle} )*/ -@d math_comp 50 /*component of formula ( \.{\\mathbin}, etc.~)*/ -@d limit_switch 51 /*diddle limit conventions ( \.{\\displaylimits}, etc.~)*/ -@d above 52 /*generalized fraction ( \.{\\above}, \.{\\atop}, etc.~)*/ -@d math_style 53 /*style specification ( \.{\\displaystyle}, etc.~)*/ -@d math_choice 54 /*choice specification ( \.{\\mathchoice} )*/ -@d non_script 55 /*conditional math glue ( \.{\\nonscript} )*/ -@d vcenter 56 /*vertically center a vbox ( \.{\\vcenter} )*/ -@d case_shift 57 /*force specific case ( \.{\\lowercase}, \.{\\uppercase}~)*/ -@d message 58 /*send to user ( \.{\\message}, \.{\\errmessage} )*/ -@d extension 59 /*extensions to \TeX\ ( \.{\\write}, \.{\\special}, etc.~)*/ -@d in_stream 60 /*files for reading ( \.{\\openin}, \.{\\closein} )*/ -@d begin_group 61 /*begin local grouping ( \.{\\begingroup} )*/ -@d end_group 62 /*end local grouping ( \.{\\endgroup} )*/ -@d omit 63 /*omit alignment template ( \.{\\omit} )*/ -@d ex_space 64 /*explicit space ( \.{\\\ } )*/ -@d no_boundary 65 /*suppress boundary ligatures ( \.{\\noboundary} )*/ -@d radical 66 /*square root and similar signs ( \.{\\radical} )*/ -@d end_cs_name 67 /*end control sequence ( \.{\\endcsname} )*/ -@d min_internal 68 /*the smallest code that can follow \.{\\the}*/ -@d char_given 68 /*character code defined by \.{\\chardef}*/ -@d math_given 69 /*math code defined by \.{\\mathchardef}*/ -@d last_item 70 /*most recent item ( \.{\\lastpenalty}, - \.{\\lastkern}, \.{\\lastskip} )*/ -@d max_non_prefixed_command 70 /*largest command code that can't be \.{\\global}*/ - -@ The next codes are special; they all relate to mode-independent -assignment of values to \TeX's internal registers or tables. -Codes that are |max_internal| or less represent internal quantities -that might be expanded by `\.{\\the}'. - -@d toks_register 71 /*token list register ( \.{\\toks} )*/ -@d assign_toks 72 /*special token list ( \.{\\output}, \.{\\everypar}, etc.~)*/ -@d assign_int 73 /*user-defined integer ( \.{\\tolerance}, \.{\\day}, etc.~)*/ -@d assign_dimen 74 /*user-defined length ( \.{\\hsize}, etc.~)*/ -@d assign_glue 75 /*user-defined glue ( \.{\\baselineskip}, etc.~)*/ -@d assign_mu_glue 76 /*user-defined muglue ( \.{\\thinmuskip}, etc.~)*/ -@d assign_font_dimen 77 /*user-defined font dimension ( \.{\\fontdimen} )*/ -@d assign_font_int 78 /*user-defined font integer ( \.{\\hyphenchar}, - \.{\\skewchar} )*/ -@d set_aux 79 /*specify state info ( \.{\\spacefactor}, \.{\\prevdepth} )*/ -@d set_prev_graf 80 /*specify state info ( \.{\\prevgraf} )*/ -@d set_page_dimen 81 /*specify state info ( \.{\\pagegoal}, etc.~)*/ -@d set_page_int 82 /*specify state info ( \.{\\deadcycles}, - \.{\\insertpenalties} )*/ - /*( or \.{\\interactionmode} )*/ -@d set_box_dimen 83 /*change dimension of box ( \.{\\wd}, \.{\\ht}, \.{\\dp} )*/ -@d set_shape 84 /*specify fancy paragraph shape ( \.{\\parshape} )*/ - /*(or \.{\\interlinepenalties}, etc.~)*/ -@d def_code 85 /*define a character code ( \.{\\catcode}, etc.~)*/ -@d def_family 86 /*declare math fonts ( \.{\\textfont}, etc.~)*/ -@d set_font 87 /*set current font ( font identifiers )*/ -@d def_font 88 /*define a font file ( \.{\\font} )*/ -@d internal_register 89 /*internal register ( \.{\\count}, \.{\\dimen}, etc.~)*/ -@d max_internal 89 /*the largest code that can follow \.{\\the}*/ -@d advance 90 /*advance a register or parameter ( \.{\\advance} )*/ -@d multiply 91 /*multiply a register or parameter ( \.{\\multiply} )*/ -@d divide 92 /*divide a register or parameter ( \.{\\divide} )*/ -@d prefix 93 /*qualify a definition ( \.{\\global}, \.{\\long}, \.{\\outer} )*/ - /*( or \.{\\protected} )*/ -@d let 94 /*assign a command code ( \.{\\let}, \.{\\futurelet} )*/ -@d shorthand_def 95 /*code definition ( \.{\\chardef}, \.{\\countdef}, etc.~)*/ -@d read_to_cs 96 /*read into a control sequence ( \.{\\read} )*/ - /*( or \.{\\readline} )*/ -@d def 97 /*macro definition ( \.{\\def}, \.{\\gdef}, \.{\\xdef}, \.{\\edef} )*/ -@d set_box 98 /*set a box ( \.{\\setbox} )*/ -@d hyph_data 99 /*hyphenation data ( \.{\\hyphenation}, \.{\\patterns} )*/ -@d set_interaction 100 /*define level of interaction ( \.{\\batchmode}, etc.~)*/ -@d max_command 100 /*the largest command code seen at |big_switch|*/ - -@ The remaining command codes are extra special, since they cannot get through -\TeX's scanner to the main control routine. They have been given values higher -than |max_command| so that their special nature is easily discernible. -The ``expandable'' commands come first. - -@d undefined_cs (max_command+1) /*initial state of most |eq_type| fields*/ -@d expand_after (max_command+2) /*special expansion ( \.{\\expandafter} )*/ -@d no_expand (max_command+3) /*special nonexpansion ( \.{\\noexpand} )*/ -@d input (max_command+4) /*input a source file ( \.{\\input}, \.{\\endinput} )*/ - /*( or \.{\\scantokens} )*/ -@d if_test (max_command+5) /*conditional text ( \.{\\if}, \.{\\ifcase}, etc.~)*/ -@d fi_or_else (max_command+6) /*delimiters for conditionals ( \.{\\else}, etc.~)*/ -@d cs_name (max_command+7) /*make a control sequence from tokens ( \.{\\csname} )*/ -@d convert (max_command+8) /*convert to text ( \.{\\number}, \.{\\string}, etc.~)*/ -@d the (max_command+9) /*expand an internal quantity ( \.{\\the} )*/ - /*( or \.{\\unexpanded}, \.{\\detokenize} )*/ -@d top_bot_mark (max_command+10) /*inserted mark ( \.{\\topmark}, etc.~)*/ -@d call (max_command+11) /*non-long, non-outer control sequence*/ -@d long_call (max_command+12) /*long, non-outer control sequence*/ -@d outer_call (max_command+13) /*non-long, outer control sequence*/ -@d long_outer_call (max_command+14) /*long, outer control sequence*/ -@d end_template (max_command+15) /*end of an alignment template*/ -@d dont_expand (max_command+16) /*the following token was marked by \.{\\noexpand}*/ -@d glue_ref (max_command+17) /*the equivalent points to a glue specification*/ -@d shape_ref (max_command+18) /*the equivalent points to a parshape specification*/ -@d box_ref (max_command+19) /*the equivalent points to a box node, or is |null|*/ -@d data (max_command+20) /*the equivalent is simply a halfword number*/ - -@* The semantic nest. -\TeX\ is typically in the midst of building many lists at once. For example, -when a math formula is being processed, \TeX\ is in math mode and -working on an mlist; this formula has temporarily interrupted \TeX\ from -being in horizontal mode and building the hlist of a paragraph; and this -paragraph has temporarily interrupted \TeX\ from being in vertical mode -and building the vlist for the next page of a document. Similarly, when a -\.{\\vbox} occurs inside of an \.{\\hbox}, \TeX\ is temporarily -interrupted from working in restricted horizontal mode, and it enters -internal vertical mode. The ``semantic nest'' is a stack that -keeps track of what lists and modes are currently suspended. - -At each level of processing we are in one of six modes: - -\yskip\hang|vmode| stands for vertical mode (the page builder); - -\hang|hmode| stands for horizontal mode (the paragraph builder); - -\hang|mmode| stands for displayed formula mode; - -\hang|-vmode| stands for internal vertical mode (e.g., in a \.{\\vbox}); - -\hang|-hmode| stands for restricted horizontal mode (e.g., in an \.{\\hbox}); - -\hang|-mmode| stands for math formula mode (not displayed). - -\yskip\noindent The mode is temporarily set to zero while processing \.{\\write} -texts. - -Numeric values are assigned to |vmode|, |hmode|, and |mmode| so that -\TeX's ``big semantic switch'' can select the appropriate thing to -do by computing the value |abs(mode)+cur_cmd|, where |mode| is the current -mode and |cur_cmd| is the current command code. - -@d vmode 1 /*vertical mode*/ -@d hmode (vmode+max_command+1) /*horizontal mode*/ -@d mmode (hmode+max_command+1) /*math mode*/ - -@p static void print_mode(int @!m) /*prints the mode represented by |m|*/ -{@+if (m > 0) - switch (m/(max_command+1)) { - case 0: print("vertical");@+break; - case 1: print("horizontal");@+break; - case 2: print("display math"); - } -else if (m==0) print("no"); -else switch ((-m)/(max_command+1)) { - case 0: print("internal vertical");@+break; - case 1: print("restricted horizontal");@+break; - case 2: print("math"); - } -print(" mode"); -} - -@ The state of affairs at any semantic level can be represented by -five values: - -\yskip\hang|mode| is the number representing the semantic mode, as -just explained. - -\yskip\hang|head| is a |pointer| to a list head for the list being built; -|link(head)| therefore points to the first element of the list, or -to |null| if the list is empty. - -\yskip\hang|tail| is a |pointer| to the final node of the list being -built; thus, |tail==head| if and only if the list is empty. - -\yskip\hang|prev_graf| is the number of lines of the current paragraph that -have already been put into the present vertical list. - -\yskip\hang|aux| is an auxiliary |memory_word| that gives further information -that is needed to characterize the situation. - -\yskip\noindent -In vertical mode, |aux| is also known as |prev_depth|; it is the scaled -value representing the depth of the previous box, for use in baseline -calculations, or it is | <= -1000|pt if the next box on the vertical list is to -be exempt from baseline calculations. In horizontal mode, |aux| is also -known as |space_factor| and |clang|; it holds the current space factor used in -spacing calculations, and the current language used for hyphenation. -(The value of |clang| is undefined in restricted horizontal mode.) -In math mode, |aux| is also known as |incompleat_noad|; if -not |null|, it points to a record that represents the numerator of a -generalized fraction for which the denominator is currently being formed -in the current list. - -There is also a sixth quantity, |mode_line|, which correlates -the semantic nest with the user's input; |mode_line| contains the source -line number at which the current level of nesting was entered. The negative -of this line number is the |mode_line| at the level of the -user's output routine. - -A seventh quantity, |eTeX_aux|, is used by the extended features \eTeX. -In vertical modes it is known as |LR_save| and holds the LR stack when a -paragraph is interrupted by a displayed formula. In display math mode -it is known as |LR_box| and holds a pointer to a prototype box for the -display. In math mode it is known as |delim_ptr| and points to the most -recent |left_noad| or |middle_noad| of a |math_left_group|. - -In horizontal mode, the |prev_graf| field is used for initial language data. - -The semantic nest is an array called |nest| that holds the |mode|, |head|, -|tail|, |prev_graf|, |aux|, and |mode_line| values for all semantic levels -below the currently active one. Information about the currently active -level is kept in the global quantities |mode|, |head|, |tail|, |prev_graf|, -|aux|, and |mode_line|, which live in a \PASCAL\ record that is ready to -be pushed onto |nest| if necessary. - -@d ignore_depth (-1000*unity) /*|prev_depth| value that is ignored*/ -@d unknown_depth (-2000*unity) /*|prev_depth| value that is unknown*/ - -@<Types...@>= -typedef struct { int16_t @!mode_field;@+ - pointer @!head_field, @!tail_field; - pointer @!eTeX_aux_field; - int @!pg_field, @!ml_field;@+ - memory_word @!aux_field; - } list_state_record; - -@ @d mode cur_list.mode_field /*current mode*/ -@d head cur_list.head_field /*header node of current list*/ -@d tail cur_list.tail_field /*final node on current list*/ -@d eTeX_aux cur_list.eTeX_aux_field /*auxiliary data for \eTeX*/ -@d LR_save eTeX_aux /*LR stack when a paragraph is interrupted*/ -@d LR_box eTeX_aux /*prototype box for display*/ -@d delim_ptr eTeX_aux /*most recent left or right noad of a math left group*/ -@d prev_graf cur_list.pg_field /*number of paragraph lines accumulated*/ -@d aux cur_list.aux_field /*auxiliary data about the current list*/ -@d prev_depth aux.sc /*the name of |aux| in vertical mode*/ -@d space_factor aux.hh.lh /*part of |aux| in horizontal mode*/ -@d clang aux.hh.rh /*the other part of |aux| in horizontal mode*/ -@d incompleat_noad aux.i /*the name of |aux| in math mode*/ -@d mode_line cur_list.ml_field /*source file line number at beginning of list*/ - -@<Glob...@>= -list_state_record @!nest[nest_size+1]; -int @!nest_ptr; /*first unused location of |nest|*/ -static int @!max_nest_stack; /*maximum of |nest_ptr| when pushing*/ -list_state_record @!cur_list; /*the ``top'' semantic state*/ -static int @!shown_mode; /*most recent mode shown by \.{\\tracingcommands}*/ - -@ Here is a common way to make the current list grow: - -@d tail_append(A) {@+link(tail)=A;tail=link(tail); - } - -@ We will see later that the vertical list at the bottom semantic level is split -into two parts; the ``current page'' runs from |page_head| to |page_tail|, -and the ``contribution list'' runs from |contrib_head| to |tail| of -semantic level zero. The idea is that contributions are first formed in -vertical mode, then ``contributed'' to the current page (during which time -the page-breaking decisions are made). For now, we don't need to know -any more details about the page-building process. - -@<Set init...@>= -nest_ptr=0;max_nest_stack=0; -mode=vmode;head=contrib_head;tail=contrib_head; -eTeX_aux=null; -prev_depth=ignore_depth;mode_line=0; -prev_graf=0;shown_mode=0; -@<Start a new current page@>; - -@ When \TeX's work on one level is interrupted, the state is saved by -calling |push_nest|. This routine changes |head| and |tail| so that -a new (empty) list is begun; it does not change |mode| or |aux|. - -@p void push_nest(void) /*enter a new semantic level, save the old*/ -{@+if (nest_ptr > max_nest_stack) - {@+max_nest_stack=nest_ptr; - if (nest_ptr==nest_size) overflow("semantic nest size", nest_size); -@:TeX capacity exceeded semantic nest size}{\quad semantic nest size@> - } -nest[nest_ptr]=cur_list; /*stack the record*/ -incr(nest_ptr);head=get_avail();tail=head;prev_graf=0;mode_line=line; -eTeX_aux=null; -} - -@ Conversely, when \TeX\ is finished on the current level, the former -state is restored by calling |pop_nest|. This routine will never be -called at the lowest semantic level, nor will it be called unless |head| -is a node that should be returned to free memory. - -@p void pop_nest(void) /*leave a semantic level, re-enter the old*/ -{@+free_avail(head);decr(nest_ptr);cur_list=nest[nest_ptr]; -} - -@ Here is a procedure that displays what \TeX\ is working on, at all levels. - -@p static void print_totals(void); -static void show_activities(void) -{@+int p; /*index into |nest|*/ -int @!m; /*mode*/ -memory_word @!a; /*auxiliary*/ -pointer @!q, @!r; /*for showing the current page*/ -int @!t; /*ditto*/ -nest[nest_ptr]=cur_list; /*put the top level into the array*/ -print_nl("");print_ln(); -for (p=nest_ptr; p>=0; p--) - {@+m=nest[p].mode_field;a=nest[p].aux_field; - print_nl("### ");print_mode(m); - print(" entered at line ");print_int(abs(nest[p].ml_field)); - if (m==hmode) if (nest[p].pg_field!=040600000) - {@+print(" (language");print_int(nest[p].pg_field%0200000); - print(":hyphenmin");print_int(nest[p].pg_field/020000000); - print_char(',');print_int((nest[p].pg_field/0200000)%0100); - print_char(')'); - } - if (nest[p].ml_field < 0) print(" (\\output routine)"); - if (p==0) - {@+@<Show the status of the current page@>; - if (link(contrib_head)!=null) - print_nl("### recent contributions:"); - } - show_box(link(nest[p].head_field)); - @<Show the auxiliary field, |a|@>; - } -} - -@ @<Show the auxiliary...@>= -switch (abs(m)/(max_command+1)) { -case 0: {@+print_nl("prevdepth "); - if (a.sc <= ignore_depth) - { if (a.sc <= unknown_depth) print("unknown"); else print("ignored"); } - else print_scaled(a.sc); - if (nest[p].pg_field!=0) - {@+print(", prevgraf "); - print_int(nest[p].pg_field);print(" line"); - if (nest[p].pg_field!=1) print_char('s'); - } - } @+break; -case 1: {@+print_nl("spacefactor ");print_int(a.hh.lh); - if (m > 0) @+if (a.hh.rh > 0) - {@+print(", current language ");print_int(a.hh.rh);@+ - } - } @+break; -case 2: if (a.i!=null) - {@+print("this will begin denominator of:");show_box(a.i);@+ - } -} /*there are no other cases*/ - -@* The table of equivalents. -Now that we have studied the data structures for \TeX's semantic routines, -we ought to consider the data structures used by its syntactic routines. In -other words, our next concern will be -the tables that \TeX\ looks at when it is scanning -what the user has written. - -The biggest and most important such table is called |eqtb|. It holds the -current ``equivalents'' of things; i.e., it explains what things mean -or what their current values are, for all quantities that are subject to -the nesting structure provided by \TeX's grouping mechanism. There are six -parts to |eqtb|: - -\yskip\hangg 1) |eqtb[active_base dotdot(hash_base-1)]| holds the current -equivalents of single-character control sequences. - -\yskip\hangg 2) |eqtb[hash_base dotdot(glue_base-1)]| holds the current -equivalents of multiletter control sequences. - -\yskip\hangg 3) |eqtb[glue_base dotdot(local_base-1)]| holds the current -equivalents of glue parameters like the current baselineskip. - -\yskip\hangg 4) |eqtb[local_base dotdot(int_base-1)]| holds the current -equivalents of local halfword quantities like the current box registers, -the current ``catcodes,'' the current font, and a pointer to the current -paragraph shape. - -\yskip\hangg 5) |eqtb[int_base dotdot(dimen_base-1)]| holds the current -equivalents of fullword integer parameters like the current hyphenation -penalty. - -\yskip\hangg 6) |eqtb[dimen_base dotdot eqtb_size]| holds the current equivalents -of fullword dimension parameters like the current hsize or amount of -hanging indentation. - -\yskip\noindent Note that, for example, the current amount of -baselineskip glue is determined by the setting of a particular location -in region~3 of |eqtb|, while the current meaning of the control sequence -`\.{\\baselineskip}' (which might have been changed by \.{\\def} or -\.{\\let}) appears in region~2. - -@ Each entry in |eqtb| is a |memory_word|. Most of these words are of type -|two_halves|, and subdivided into three fields: - -\yskip\hangg 1) The |eq_level| (a quarterword) is the level of grouping at -which this equivalent was defined. If the level is |level_zero|, the -equivalent has never been defined; |level_one| refers to the outer level -(outside of all groups), and this level is also used for global -definitions that never go away. Higher levels are for equivalents that -will disappear at the end of their group. @^global definitions@> - -\yskip\hangg 2) The |eq_type| (another quarterword) specifies what kind of -entry this is. There are many types, since each \TeX\ primitive like -\.{\\hbox}, \.{\\def}, etc., has its own special code. The list of -command codes above includes all possible settings of the |eq_type| field. - -\yskip\hangg 3) The |equiv| (a halfword) is the current equivalent value. -This may be a font number, a pointer into |mem|, or a variety of other -things. - -@d eq_level_field(A) A.hh.b1 -@d eq_type_field(A) A.hh.b0 -@d equiv_field(A) A.hh.rh -@d eq_level(A) eq_level_field(eqtb[A]) /*level of definition*/ -@d eq_type(A) eq_type_field(eqtb[A]) /*command code for equivalent*/ -@d equiv(A) equiv_field(eqtb[A]) /*equivalent value*/ -@d level_zero min_quarterword /*level for undefined quantities*/ -@d level_one (level_zero+1) /*outermost level for defined quantities*/ - -@ Many locations in |eqtb| have symbolic names. The purpose of the next -paragraphs is to define these names, and to set up the initial values of the -equivalents. - -In the first region we have 256 equivalents for ``active characters'' that -act as control sequences, followed by 256 equivalents for single-character -control sequences. - -Then comes region~2, which corresponds to the hash table that we will -define later. The maximum address in this region is used for a dummy -control sequence that is perpetually undefined. There also are several -locations for control sequences that are perpetually defined -(since they are used in error recovery). - -@d active_base 1 /*beginning of region 1, for active character equivalents*/ -@d single_base (active_base+256) /*equivalents of one-character control sequences*/ -@d null_cs (single_base+256) /*equivalent of \.{\\csname\\endcsname}*/ -@d hash_base (null_cs+1) /*beginning of region 2, for the hash table*/ -@d frozen_control_sequence (hash_base+hash_size) /*for error recovery*/ -@d frozen_protection frozen_control_sequence /*inaccessible but definable*/ -@d frozen_cr (frozen_control_sequence+1) /*permanent `\.{\\cr}'*/ -@d frozen_end_group (frozen_control_sequence+2) /*permanent `\.{\\endgroup}'*/ -@d frozen_right (frozen_control_sequence+3) /*permanent `\.{\\right}'*/ -@d frozen_fi (frozen_control_sequence+4) /*permanent `\.{\\fi}'*/ -@d frozen_end_template (frozen_control_sequence+5) /*permanent `\.{\\endtemplate}'*/ -@d frozen_endv (frozen_control_sequence+6) /*second permanent `\.{\\endtemplate}'*/ -@d frozen_relax (frozen_control_sequence+7) /*permanent `\.{\\relax}'*/ -@d end_write (frozen_control_sequence+8) /*permanent `\.{\\endwrite}'*/ -@d frozen_dont_expand (frozen_control_sequence+9) - /*permanent `\.{\\notexpanded:}'*/ -@d frozen_null_font (frozen_control_sequence+10) - /*permanent `\.{\\nullfont}'*/ -@d font_id_base (frozen_null_font-font_base) - /*begins table of 257 permanent font identifiers*/ -@d undefined_control_sequence (frozen_null_font+257) /*dummy location*/ -@d glue_base (undefined_control_sequence+1) /*beginning of region 3*/ - -@<Initialize table entries...@>= -eq_type(undefined_control_sequence)=undefined_cs; -equiv(undefined_control_sequence)=null; -eq_level(undefined_control_sequence)=level_zero; -for (k=active_base; k<=undefined_control_sequence-1; k++) - eqtb[k]=eqtb[undefined_control_sequence]; - -@ Here is a routine that displays the current meaning of an |eqtb| entry -in region 1 or~2. (Similar routines for the other regions will appear -below.) - -@<Show equivalent |n|, in region 1 or 2@>= -{@+sprint_cs(n);print_char('=');print_cmd_chr(eq_type(n), equiv(n)); -if (eq_type(n) >= call) - {@+print_char(':');show_token_list(link(equiv(n)), null, 32); - } -} - -@ Region 3 of |eqtb| contains the 256 \.{\\skip} registers, as well as the -glue parameters defined here. It is important that the ``muskip'' -parameters have larger numbers than the others. - -@d line_skip_code 0 /*interline glue if |baseline_skip| is infeasible*/ -@d baseline_skip_code 1 /*desired glue between baselines*/ -@d par_skip_code 2 /*extra glue just above a paragraph*/ -@d above_display_skip_code 3 /*extra glue just above displayed math*/ -@d below_display_skip_code 4 /*extra glue just below displayed math*/ -@d above_display_short_skip_code 5 - /*glue above displayed math following short lines*/ -@d below_display_short_skip_code 6 - /*glue below displayed math following short lines*/ -@d left_skip_code 7 /*glue at left of justified lines*/ -@d right_skip_code 8 /*glue at right of justified lines*/ -@d top_skip_code 9 /*glue at top of main pages*/ -@d split_top_skip_code 10 /*glue at top of split pages*/ -@d tab_skip_code 11 /*glue between aligned entries*/ -@d space_skip_code 12 /*glue between words (if not |zero_glue|)*/ -@d xspace_skip_code 13 /*glue after sentences (if not |zero_glue|)*/ -@d par_fill_skip_code 14 /*glue on last line of paragraph*/ -@d thin_mu_skip_code 15 /*thin space in math formula*/ -@d med_mu_skip_code 16 /*medium space in math formula*/ -@d thick_mu_skip_code 17 /*thick space in math formula*/ -@d glue_pars 18 /*total number of glue parameters*/ -@d skip_base (glue_base+glue_pars) /*table of 256 ``skip'' registers*/ -@d mu_skip_base (skip_base+256) /*table of 256 ``muskip'' registers*/ -@d local_base (mu_skip_base+256) /*beginning of region 4*/ -@# -@d skip(A) equiv(skip_base+A) /*|mem| location of glue specification*/ -@d mu_skip(A) equiv(mu_skip_base+A) /*|mem| location of math glue spec*/ -@d glue_par(A) equiv(glue_base+A) /*|mem| location of glue specification*/ -@d line_skip glue_par(line_skip_code) -@d baseline_skip glue_par(baseline_skip_code) -@d par_skip glue_par(par_skip_code) -@d above_display_skip glue_par(above_display_skip_code) -@d below_display_skip glue_par(below_display_skip_code) -@d above_display_short_skip glue_par(above_display_short_skip_code) -@d below_display_short_skip glue_par(below_display_short_skip_code) -@d left_skip glue_par(left_skip_code) -@d right_skip glue_par(right_skip_code) -@d top_skip glue_par(top_skip_code) -@d split_top_skip glue_par(split_top_skip_code) -@d tab_skip glue_par(tab_skip_code) -@d space_skip glue_par(space_skip_code) -@d xspace_skip glue_par(xspace_skip_code) -@d par_fill_skip glue_par(par_fill_skip_code) -@d thin_mu_skip glue_par(thin_mu_skip_code) -@d med_mu_skip glue_par(med_mu_skip_code) -@d thick_mu_skip glue_par(thick_mu_skip_code) - -@<Current |mem| equivalent of glue parameter number |n|@>=glue_par(n) - -@ Sometimes we need to convert \TeX's internal code numbers into symbolic -form. The |print_skip_param| routine gives the symbolic name of a glue -parameter. - -@<Declare the procedure called |print_skip_param|@>= -static void print_skip_param(int @!n) -{@+switch (n) { -case line_skip_code: print_esc("lineskip");@+break; -case baseline_skip_code: print_esc("baselineskip");@+break; -case par_skip_code: print_esc("parskip");@+break; -case above_display_skip_code: print_esc("abovedisplayskip");@+break; -case below_display_skip_code: print_esc("belowdisplayskip");@+break; -case above_display_short_skip_code: print_esc("abovedisplayshortskip");@+break; -case below_display_short_skip_code: print_esc("belowdisplayshortskip");@+break; -case left_skip_code: print_esc("leftskip");@+break; -case right_skip_code: print_esc("rightskip");@+break; -case top_skip_code: print_esc("topskip");@+break; -case split_top_skip_code: print_esc("splittopskip");@+break; -case tab_skip_code: print_esc("tabskip");@+break; -case space_skip_code: print_esc("spaceskip");@+break; -case xspace_skip_code: print_esc("xspaceskip");@+break; -case par_fill_skip_code: print_esc("parfillskip");@+break; -case thin_mu_skip_code: print_esc("thinmuskip");@+break; -case med_mu_skip_code: print_esc("medmuskip");@+break; -case thick_mu_skip_code: print_esc("thickmuskip");@+break; -default:print("[unknown glue parameter!]"); -} -} - -@ The symbolic names for glue parameters are put into \TeX's hash table -by using the routine called |primitive|, defined below. Let us enter them -now, so that we don't have to list all those parameter names anywhere else. - -@<Put each of \TeX's primitives into the hash table@>= -primitive("lineskip", assign_glue, glue_base+line_skip_code);@/ -@!@:line\_skip\_}{\.{\\lineskip} primitive@> -primitive("baselineskip", assign_glue, glue_base+baseline_skip_code);@/ -@!@:baseline\_skip\_}{\.{\\baselineskip} primitive@> -primitive("parskip", assign_glue, glue_base+par_skip_code);@/ -@!@:par\_skip\_}{\.{\\parskip} primitive@> -primitive("abovedisplayskip", assign_glue, glue_base+above_display_skip_code);@/ -@!@:above\_display\_skip\_}{\.{\\abovedisplayskip} primitive@> -primitive("belowdisplayskip", assign_glue, glue_base+below_display_skip_code);@/ -@!@:below\_display\_skip\_}{\.{\\belowdisplayskip} primitive@> -primitive("abovedisplayshortskip", - assign_glue, glue_base+above_display_short_skip_code);@/ -@!@:above\_display\_short\_skip\_}{\.{\\abovedisplayshortskip} primitive@> -primitive("belowdisplayshortskip", - assign_glue, glue_base+below_display_short_skip_code);@/ -@!@:below\_display\_short\_skip\_}{\.{\\belowdisplayshortskip} primitive@> -primitive("leftskip", assign_glue, glue_base+left_skip_code);@/ -@!@:left\_skip\_}{\.{\\leftskip} primitive@> -primitive("rightskip", assign_glue, glue_base+right_skip_code);@/ -@!@:right\_skip\_}{\.{\\rightskip} primitive@> -primitive("topskip", assign_glue, glue_base+top_skip_code);@/ -@!@:top\_skip\_}{\.{\\topskip} primitive@> -primitive("splittopskip", assign_glue, glue_base+split_top_skip_code);@/ -@!@:split\_top\_skip\_}{\.{\\splittopskip} primitive@> -primitive("tabskip", assign_glue, glue_base+tab_skip_code);@/ -@!@:tab\_skip\_}{\.{\\tabskip} primitive@> -primitive("spaceskip", assign_glue, glue_base+space_skip_code);@/ -@!@:space\_skip\_}{\.{\\spaceskip} primitive@> -primitive("xspaceskip", assign_glue, glue_base+xspace_skip_code);@/ -@!@:xspace\_skip\_}{\.{\\xspaceskip} primitive@> -primitive("parfillskip", assign_glue, glue_base+par_fill_skip_code);@/ -@!@:par\_fill\_skip\_}{\.{\\parfillskip} primitive@> -primitive("thinmuskip", assign_mu_glue, glue_base+thin_mu_skip_code);@/ -@!@:thin\_mu\_skip\_}{\.{\\thinmuskip} primitive@> -primitive("medmuskip", assign_mu_glue, glue_base+med_mu_skip_code);@/ -@!@:med\_mu\_skip\_}{\.{\\medmuskip} primitive@> -primitive("thickmuskip", assign_mu_glue, glue_base+thick_mu_skip_code);@/ -@!@:thick\_mu\_skip\_}{\.{\\thickmuskip} primitive@> - -@ @<Cases of |print_cmd_chr| for symbolic printing of primitives@>= -case assign_glue: case assign_mu_glue: if (chr_code < skip_base) - print_skip_param(chr_code-glue_base); - else if (chr_code < mu_skip_base) - {@+print_esc("skip");print_int(chr_code-skip_base); - } - else{@+print_esc("muskip");print_int(chr_code-mu_skip_base); - } @+break; - -@ All glue parameters and registers are initially `\.{0pt plus0pt minus0pt}'. - -@<Initialize table entries...@>= -equiv(glue_base)=zero_glue;eq_level(glue_base)=level_one; -eq_type(glue_base)=glue_ref; -for (k=glue_base+1; k<=local_base-1; k++) eqtb[k]=eqtb[glue_base]; -glue_ref_count(zero_glue)=glue_ref_count(zero_glue)+local_base-glue_base; - -@ @<Show equivalent |n|, in region 3@>= -if (n < skip_base) - {@+print_skip_param(n-glue_base);print_char('='); - if (n < glue_base+thin_mu_skip_code) print_spec(equiv(n),"pt"); - else print_spec(equiv(n),"mu"); - } -else if (n < mu_skip_base) - {@+print_esc("skip");print_int(n-skip_base);print_char('='); - print_spec(equiv(n),"pt"); - } -else{@+print_esc("muskip");print_int(n-mu_skip_base);print_char('='); - print_spec(equiv(n),"mu"); - } - -@ Region 4 of |eqtb| contains the local quantities defined here. The -bulk of this region is taken up by five tables that are indexed by eight-bit -characters; these tables are important to both the syntactic and semantic -portions of \TeX. There are also a bunch of special things like font and -token parameters, as well as the tables of \.{\\toks} and \.{\\box} -registers. - -@d par_shape_loc local_base /*specifies paragraph shape*/ -@d output_routine_loc (local_base+1) /*points to token list for \.{\\output}*/ -@d every_par_loc (local_base+2) /*points to token list for \.{\\everypar}*/ -@d every_math_loc (local_base+3) /*points to token list for \.{\\everymath}*/ -@d every_display_loc (local_base+4) /*points to token list for \.{\\everydisplay}*/ -@d every_hbox_loc (local_base+5) /*points to token list for \.{\\everyhbox}*/ -@d every_vbox_loc (local_base+6) /*points to token list for \.{\\everyvbox}*/ -@d every_job_loc (local_base+7) /*points to token list for \.{\\everyjob}*/ -@d every_cr_loc (local_base+8) /*points to token list for \.{\\everycr}*/ -@d err_help_loc (local_base+9) /*points to token list for \.{\\errhelp}*/ -@d tex_toks (local_base+10) /*end of \TeX's token list parameters*/ -@# -@d etex_toks_base tex_toks /*base for \eTeX's token list parameters*/ -@d every_eof_loc etex_toks_base /*points to token list for \.{\\everyeof}*/ -@d etex_toks (etex_toks_base+1) /*end of \eTeX's token list parameters*/ -@# -@d toks_base etex_toks /*table of 256 token list registers*/ -@# -@d etex_pen_base (toks_base+256) /*start of table of \eTeX's penalties*/ -@d inter_line_penalties_loc etex_pen_base /*additional penalties between lines*/ -@d club_penalties_loc (etex_pen_base+1) /*penalties for creating club lines*/ -@d widow_penalties_loc (etex_pen_base+2) /*penalties for creating widow lines*/ -@d display_widow_penalties_loc (etex_pen_base+3) /*ditto, just before a display*/ -@d etex_pens (etex_pen_base+4) /*end of table of \eTeX's penalties*/ -@# -@d box_base etex_pens /*table of 256 box registers*/ -@d cur_font_loc (box_base+256) /*internal font number outside math mode*/ -@d math_font_base (cur_font_loc+1) /*table of 48 math font numbers*/ -@d cat_code_base (math_font_base+48) - /*table of 256 command codes (the ``catcodes'')*/ -@d lc_code_base (cat_code_base+256) /*table of 256 lowercase mappings*/ -@d uc_code_base (lc_code_base+256) /*table of 256 uppercase mappings*/ -@d sf_code_base (uc_code_base+256) /*table of 256 spacefactor mappings*/ -@d math_code_base (sf_code_base+256) /*table of 256 math mode mappings*/ -@d int_base (math_code_base+256) /*beginning of region 5*/ -@# -@d par_shape_ptr equiv(par_shape_loc) -@d output_routine equiv(output_routine_loc) -@d every_par equiv(every_par_loc) -@d every_math equiv(every_math_loc) -@d every_display equiv(every_display_loc) -@d every_hbox equiv(every_hbox_loc) -@d every_vbox equiv(every_vbox_loc) -@d every_job equiv(every_job_loc) -@d every_cr equiv(every_cr_loc) -@d err_help equiv(err_help_loc) -@d toks(X) equiv(toks_base+X) -@d box(A) equiv(box_base+A) -@d cur_font equiv(cur_font_loc) -@d fam_fnt(A) equiv(math_font_base+A) -@d cat_code(A) equiv(cat_code_base+A) -@d lc_code(A) equiv(lc_code_base+A) -@d uc_code(A) equiv(uc_code_base+A) -@d sf_code(A) equiv(sf_code_base+A) -@d math_code(A) equiv(math_code_base+A) - /*Note: |math_code(c)| is the true math code plus |min_halfword|*/ - -@<Put each...@>= -primitive("output", assign_toks, output_routine_loc); -@!@:output\_}{\.{\\output} primitive@> -primitive("everypar", assign_toks, every_par_loc); -@!@:every\_par\_}{\.{\\everypar} primitive@> -primitive("everymath", assign_toks, every_math_loc); -@!@:every\_math\_}{\.{\\everymath} primitive@> -primitive("everydisplay", assign_toks, every_display_loc); -@!@:every\_display\_}{\.{\\everydisplay} primitive@> -primitive("everyhbox", assign_toks, every_hbox_loc); -@!@:every\_hbox\_}{\.{\\everyhbox} primitive@> -primitive("everyvbox", assign_toks, every_vbox_loc); -@!@:every\_vbox\_}{\.{\\everyvbox} primitive@> -primitive("everyjob", assign_toks, every_job_loc); -@!@:every\_job\_}{\.{\\everyjob} primitive@> -primitive("everycr", assign_toks, every_cr_loc); -@!@:every\_cr\_}{\.{\\everycr} primitive@> -primitive("errhelp", assign_toks, err_help_loc); -@!@:err\_help\_}{\.{\\errhelp} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case assign_toks: if (chr_code >= toks_base) - {@+print_esc("toks");print_int(chr_code-toks_base); - } -else switch (chr_code) { - case output_routine_loc: print_esc("output");@+break; - case every_par_loc: print_esc("everypar");@+break; - case every_math_loc: print_esc("everymath");@+break; - case every_display_loc: print_esc("everydisplay");@+break; - case every_hbox_loc: print_esc("everyhbox");@+break; - case every_vbox_loc: print_esc("everyvbox");@+break; - case every_job_loc: print_esc("everyjob");@+break; - case every_cr_loc: print_esc("everycr");@+break; - @/@<Cases of |assign_toks| for |print_cmd_chr|@>@/ - default:print_esc("errhelp"); - } @+break; - -@ We initialize most things to null or undefined values. An undefined font -is represented by the internal code |font_base|. - -However, the character code tables are given initial values based on the -conventional interpretation of ASCII code. These initial values should -not be changed when \TeX\ is adapted for use with non-English languages; -all changes to the initialization conventions should be made in format -packages, not in \TeX\ itself, so that global interchange of formats is -possible. - -@d null_font font_base -@d var_code 070000 /*math code meaning ``use the current family''*/ - -@<Initialize table entries...@>= -par_shape_ptr=null;eq_type(par_shape_loc)=shape_ref; -eq_level(par_shape_loc)=level_one;@/ -for (k=etex_pen_base; k<=etex_pens-1; k++) - eqtb[k]=eqtb[par_shape_loc]; -for (k=output_routine_loc; k<=toks_base+255; k++) - eqtb[k]=eqtb[undefined_control_sequence]; -box(0)=null;eq_type(box_base)=box_ref;eq_level(box_base)=level_one; -for (k=box_base+1; k<=box_base+255; k++) eqtb[k]=eqtb[box_base]; -cur_font=null_font;eq_type(cur_font_loc)=data; -eq_level(cur_font_loc)=level_one;@/ -for (k=math_font_base; k<=math_font_base+47; k++) eqtb[k]=eqtb[cur_font_loc]; -equiv(cat_code_base)=0;eq_type(cat_code_base)=data; -eq_level(cat_code_base)=level_one;@/ -for (k=cat_code_base+1; k<=int_base-1; k++) eqtb[k]=eqtb[cat_code_base]; -for (k=0; k<=255; k++) - {@+cat_code(k)=other_char;math_code(k)=hi(k);sf_code(k)=1000; - } -cat_code(carriage_return)=car_ret;cat_code(' ')=spacer; -cat_code('\\')=escape;cat_code('%')=comment; -cat_code(invalid_code)=invalid_char;cat_code(null_code)=ignore; -for (k='0'; k<='9'; k++) math_code(k)=hi(k+var_code); -for (k='A'; k<='Z'; k++) - {@+cat_code(k)=letter;cat_code(k+'a'-'A')=letter;@/ - math_code(k)=hi(k+var_code+0x100); - math_code(k+'a'-'A')=hi(k+'a'-'A'+var_code+0x100);@/ - lc_code(k)=k+'a'-'A';lc_code(k+'a'-'A')=k+'a'-'A';@/ - uc_code(k)=k;uc_code(k+'a'-'A')=k;@/ - sf_code(k)=999; - } - -@ @<Show equivalent |n|, in region 4@>= -if ((n==par_shape_loc)||((n >= etex_pen_base)&&(n < etex_pens))) - {@+print_cmd_chr(set_shape, n);print_char('='); - if (equiv(n)==null) print_char('0'); - else if (n > par_shape_loc) - {@+print_int(penalty(equiv(n)));print_char(' '); - print_int(penalty(equiv(n)+1)); - if (penalty(equiv(n)) > 1) print_esc("ETC."); - } - else print_int(info(par_shape_ptr)); - } -else if (n < toks_base) - {@+print_cmd_chr(assign_toks, n);print_char('='); - if (equiv(n)!=null) show_token_list(link(equiv(n)), null, 32); - } -else if (n < box_base) - {@+print_esc("toks");print_int(n-toks_base);print_char('='); - if (equiv(n)!=null) show_token_list(link(equiv(n)), null, 32); - } -else if (n < cur_font_loc) - {@+print_esc("box");print_int(n-box_base);print_char('='); - if (equiv(n)==null) print("void"); - else{@+depth_threshold=0;breadth_max=1;show_node_list(equiv(n)); - } - } -else if (n < cat_code_base) @<Show the font identifier in |eqtb[n]|@>@; -else@<Show the halfword code in |eqtb[n]|@>@; - -@ @<Show the font identifier in |eqtb[n]|@>= -{@+if (n==cur_font_loc) print("current font"); -else if (n < math_font_base+16) - {@+print_esc("textfont");print_int(n-math_font_base); - } -else if (n < math_font_base+32) - {@+print_esc("scriptfont");print_int(n-math_font_base-16); - } -else{@+print_esc("scriptscriptfont");print_int(n-math_font_base-32); - } -print_char('=');@/ -printn_esc(hash[font_id_base+equiv(n)].rh); - /*that's |font_id_text(equiv(n))|*/ -} - -@ @<Show the halfword code in |eqtb[n]|@>= -if (n < math_code_base) - {@+if (n < lc_code_base) - {@+print_esc("catcode");print_int(n-cat_code_base); - } - else if (n < uc_code_base) - {@+print_esc("lccode");print_int(n-lc_code_base); - } - else if (n < sf_code_base) - {@+print_esc("uccode");print_int(n-uc_code_base); - } - else{@+print_esc("sfcode");print_int(n-sf_code_base); - } - print_char('=');print_int(equiv(n)); - } -else{@+print_esc("mathcode");print_int(n-math_code_base); - print_char('=');print_int(ho(equiv(n))); - } - -@ Region 5 of |eqtb| contains the integer parameters and registers defined -here, as well as the |del_code| table. The latter table differs from the -|cat_code dotdot math_code| tables that precede it, since delimiter codes are -fullword integers while the other kinds of codes occupy at most a -halfword. This is what makes region~5 different from region~4. We will -store the |eq_level| information in an auxiliary array of quarterwords -that will be defined later. - -@d pretolerance_code 0 /*badness tolerance before hyphenation*/ -@d tolerance_code 1 /*badness tolerance after hyphenation*/ -@d line_penalty_code 2 /*added to the badness of every line*/ -@d hyphen_penalty_code 3 /*penalty for break after discretionary hyphen*/ -@d ex_hyphen_penalty_code 4 /*penalty for break after explicit hyphen*/ -@d club_penalty_code 5 /*penalty for creating a club line*/ -@d widow_penalty_code 6 /*penalty for creating a widow line*/ -@d display_widow_penalty_code 7 /*ditto, just before a display*/ -@d broken_penalty_code 8 /*penalty for breaking a page at a broken line*/ -@d bin_op_penalty_code 9 /*penalty for breaking after a binary operation*/ -@d rel_penalty_code 10 /*penalty for breaking after a relation*/ -@d pre_display_penalty_code 11 - /*penalty for breaking just before a displayed formula*/ -@d post_display_penalty_code 12 - /*penalty for breaking just after a displayed formula*/ -@d inter_line_penalty_code 13 /*additional penalty between lines*/ -@d double_hyphen_demerits_code 14 /*demerits for double hyphen break*/ -@d final_hyphen_demerits_code 15 /*demerits for final hyphen break*/ -@d adj_demerits_code 16 /*demerits for adjacent incompatible lines*/ -@d mag_code 17 /*magnification ratio*/ -@d delimiter_factor_code 18 /*ratio for variable-size delimiters*/ -@d looseness_code 19 /*change in number of lines for a paragraph*/ -@d time_code 20 /*current time of day*/ -@d day_code 21 /*current day of the month*/ -@d month_code 22 /*current month of the year*/ -@d year_code 23 /*current year of our Lord*/ -@d show_box_breadth_code 24 /*nodes per level in |show_box|*/ -@d show_box_depth_code 25 /*maximum level in |show_box|*/ -@d hbadness_code 26 /*hboxes exceeding this badness will be shown by |hpack|*/ -@d vbadness_code 27 /*vboxes exceeding this badness will be shown by |vpack|*/ -@d pausing_code 28 /*pause after each line is read from a file*/ -@d tracing_online_code 29 /*show diagnostic output on terminal*/ -@d tracing_macros_code 30 /*show macros as they are being expanded*/ -@d tracing_stats_code 31 /*show memory usage if \TeX\ knows it*/ -@d tracing_paragraphs_code 32 /*show line-break calculations*/ -@d tracing_pages_code 33 /*show page-break calculations*/ -@d tracing_output_code 34 /*show boxes when they are shipped out*/ -@d tracing_lost_chars_code 35 /*show characters that aren't in the font*/ -@d tracing_commands_code 36 /*show command codes at |big_switch|*/ -@d tracing_restores_code 37 /*show equivalents when they are restored*/ -@d uc_hyph_code 38 /*hyphenate words beginning with a capital letter*/ -@d output_penalty_code 39 /*penalty found at current page break*/ -@d max_dead_cycles_code 40 /*bound on consecutive dead cycles of output*/ -@d hang_after_code 41 /*hanging indentation changes after this many lines*/ -@d floating_penalty_code 42 /*penalty for insertions held over after a split*/ -@d global_defs_code 43 /*override \.{\\global} specifications*/ -@d cur_fam_code 44 /*current family*/ -@d escape_char_code 45 /*escape character for token output*/ -@d default_hyphen_char_code 46 /*value of \.{\\hyphenchar} when a font is loaded*/ -@d default_skew_char_code 47 /*value of \.{\\skewchar} when a font is loaded*/ -@d end_line_char_code 48 /*character placed at the right end of the buffer*/ -@d new_line_char_code 49 /*character that prints as |print_ln|*/ -@d language_code 50 /*current hyphenation table*/ -@d left_hyphen_min_code 51 /*minimum left hyphenation fragment size*/ -@d right_hyphen_min_code 52 /*minimum right hyphenation fragment size*/ -@d holding_inserts_code 53 /*do not remove insertion nodes from \.{\\box255}*/ -@d error_context_lines_code 54 /*maximum intermediate line pairs shown*/ -@d tex_int_pars 55 /*total number of \TeX's integer parameters*/ -@# -@d etex_int_base tex_int_pars /*base for \eTeX's integer parameters*/ -@d tracing_assigns_code etex_int_base /*show assignments*/ -@d tracing_groups_code (etex_int_base+1) /*show save/restore groups*/ -@d tracing_ifs_code (etex_int_base+2) /*show conditionals*/ -@d tracing_scan_tokens_code (etex_int_base+3) /*show pseudo file open and close*/ -@d tracing_nesting_code (etex_int_base+4) /*show incomplete groups and ifs within files*/ -@d eTeX_state_code (etex_int_base+5) /*\eTeX\ state variables*/ -@d etex_int_pars (eTeX_state_code+eTeX_states) /*total number of \eTeX's integer parameters*/ -@# -@d int_pars etex_int_pars /*total number of integer parameters*/ -@d count_base (int_base+int_pars) /*256 user \.{\\count} registers*/ -@d del_code_base (count_base+256) /*256 delimiter code mappings*/ -@d dimen_base (del_code_base+256) /*beginning of region 6*/ -@# -@d del_code(A) eqtb[del_code_base+A].i -@d count(A) eqtb[count_base+A].i -@d int_par(A) eqtb[int_base+A].i /*an integer parameter*/ -@d pretolerance int_par(pretolerance_code) -@d tolerance int_par(tolerance_code) -@d line_penalty int_par(line_penalty_code) -@d hyphen_penalty int_par(hyphen_penalty_code) -@d ex_hyphen_penalty int_par(ex_hyphen_penalty_code) -@d club_penalty int_par(club_penalty_code) -@d widow_penalty int_par(widow_penalty_code) -@d display_widow_penalty int_par(display_widow_penalty_code) -@d broken_penalty int_par(broken_penalty_code) -@d bin_op_penalty int_par(bin_op_penalty_code) -@d rel_penalty int_par(rel_penalty_code) -@d pre_display_penalty int_par(pre_display_penalty_code) -@d post_display_penalty int_par(post_display_penalty_code) -@d inter_line_penalty int_par(inter_line_penalty_code) -@d double_hyphen_demerits int_par(double_hyphen_demerits_code) -@d final_hyphen_demerits int_par(final_hyphen_demerits_code) -@d adj_demerits int_par(adj_demerits_code) -@d mag int_par(mag_code) -@d delimiter_factor int_par(delimiter_factor_code) -@d looseness int_par(looseness_code) -@d time int_par(time_code) -@d day int_par(day_code) -@d month int_par(month_code) -@d year int_par(year_code) -@d show_box_breadth int_par(show_box_breadth_code) -@d show_box_depth int_par(show_box_depth_code) -@d hbadness int_par(hbadness_code) -@d vbadness int_par(vbadness_code) -@d pausing int_par(pausing_code) -@d tracing_online int_par(tracing_online_code) -@d tracing_macros int_par(tracing_macros_code) -@d tracing_stats int_par(tracing_stats_code) -@d tracing_paragraphs int_par(tracing_paragraphs_code) -@d tracing_pages int_par(tracing_pages_code) -@d tracing_output int_par(tracing_output_code) -@d tracing_lost_chars int_par(tracing_lost_chars_code) -@d tracing_commands int_par(tracing_commands_code) -@d tracing_restores int_par(tracing_restores_code) -@d uc_hyph int_par(uc_hyph_code) -@d output_penalty int_par(output_penalty_code) -@d max_dead_cycles int_par(max_dead_cycles_code) -@d hang_after int_par(hang_after_code) -@d floating_penalty int_par(floating_penalty_code) -@d global_defs int_par(global_defs_code) -@d cur_fam int_par(cur_fam_code) -@d escape_char int_par(escape_char_code) -@d default_hyphen_char int_par(default_hyphen_char_code) -@d default_skew_char int_par(default_skew_char_code) -@d end_line_char int_par(end_line_char_code) -@d new_line_char int_par(new_line_char_code) -@d language int_par(language_code) -@d left_hyphen_min int_par(left_hyphen_min_code) -@d right_hyphen_min int_par(right_hyphen_min_code) -@d holding_inserts int_par(holding_inserts_code) -@d error_context_lines int_par(error_context_lines_code) -@# -@d tracing_assigns int_par(tracing_assigns_code) -@d tracing_groups int_par(tracing_groups_code) -@d tracing_ifs int_par(tracing_ifs_code) -@d tracing_scan_tokens int_par(tracing_scan_tokens_code) -@d tracing_nesting int_par(tracing_nesting_code) - -@<Assign the values |depth_threshold:=show_box_depth|...@>= -depth_threshold=show_box_depth; -breadth_max=show_box_breadth - -@ We can print the symbolic name of an integer parameter as follows. - -@p static void print_param(int @!n) -{@+switch (n) { -case pretolerance_code: print_esc("pretolerance");@+break; -case tolerance_code: print_esc("tolerance");@+break; -case line_penalty_code: print_esc("linepenalty");@+break; -case hyphen_penalty_code: print_esc("hyphenpenalty");@+break; -case ex_hyphen_penalty_code: print_esc("exhyphenpenalty");@+break; -case club_penalty_code: print_esc("clubpenalty");@+break; -case widow_penalty_code: print_esc("widowpenalty");@+break; -case display_widow_penalty_code: print_esc("displaywidowpenalty");@+break; -case broken_penalty_code: print_esc("brokenpenalty");@+break; -case bin_op_penalty_code: print_esc("binoppenalty");@+break; -case rel_penalty_code: print_esc("relpenalty");@+break; -case pre_display_penalty_code: print_esc("predisplaypenalty");@+break; -case post_display_penalty_code: print_esc("postdisplaypenalty");@+break; -case inter_line_penalty_code: print_esc("interlinepenalty");@+break; -case double_hyphen_demerits_code: print_esc("doublehyphendemerits");@+break; -case final_hyphen_demerits_code: print_esc("finalhyphendemerits");@+break; -case adj_demerits_code: print_esc("adjdemerits");@+break; -case mag_code: print_esc("mag");@+break; -case delimiter_factor_code: print_esc("delimiterfactor");@+break; -case looseness_code: print_esc("looseness");@+break; -case time_code: print_esc("time");@+break; -case day_code: print_esc("day");@+break; -case month_code: print_esc("month");@+break; -case year_code: print_esc("year");@+break; -case show_box_breadth_code: print_esc("showboxbreadth");@+break; -case show_box_depth_code: print_esc("showboxdepth");@+break; -case hbadness_code: print_esc("hbadness");@+break; -case vbadness_code: print_esc("vbadness");@+break; -case pausing_code: print_esc("pausing");@+break; -case tracing_online_code: print_esc("tracingonline");@+break; -case tracing_macros_code: print_esc("tracingmacros");@+break; -case tracing_stats_code: print_esc("tracingstats");@+break; -case tracing_paragraphs_code: print_esc("tracingparagraphs");@+break; -case tracing_pages_code: print_esc("tracingpages");@+break; -case tracing_output_code: print_esc("tracingoutput");@+break; -case tracing_lost_chars_code: print_esc("tracinglostchars");@+break; -case tracing_commands_code: print_esc("tracingcommands");@+break; -case tracing_restores_code: print_esc("tracingrestores");@+break; -case uc_hyph_code: print_esc("uchyph");@+break; -case output_penalty_code: print_esc("outputpenalty");@+break; -case max_dead_cycles_code: print_esc("maxdeadcycles");@+break; -case hang_after_code: print_esc("hangafter");@+break; -case floating_penalty_code: print_esc("floatingpenalty");@+break; -case global_defs_code: print_esc("globaldefs");@+break; -case cur_fam_code: print_esc("fam");@+break; -case escape_char_code: print_esc("escapechar");@+break; -case default_hyphen_char_code: print_esc("defaulthyphenchar");@+break; -case default_skew_char_code: print_esc("defaultskewchar");@+break; -case end_line_char_code: print_esc("endlinechar");@+break; -case new_line_char_code: print_esc("newlinechar");@+break; -case language_code: print_esc("language");@+break; -case left_hyphen_min_code: print_esc("lefthyphenmin");@+break; -case right_hyphen_min_code: print_esc("righthyphenmin");@+break; -case holding_inserts_code: print_esc("holdinginserts");@+break; -case error_context_lines_code: print_esc("errorcontextlines");@+break; -@/@<Cases for |print_param|@>@/ -default:print("[unknown integer parameter!]"); -} -} - -@ The integer parameter names must be entered into the hash table. - -@<Put each...@>= -primitive("pretolerance", assign_int, int_base+pretolerance_code);@/ -@!@:pretolerance\_}{\.{\\pretolerance} primitive@> -primitive("tolerance", assign_int, int_base+tolerance_code);@/ -@!@:tolerance\_}{\.{\\tolerance} primitive@> -primitive("linepenalty", assign_int, int_base+line_penalty_code);@/ -@!@:line\_penalty\_}{\.{\\linepenalty} primitive@> -primitive("hyphenpenalty", assign_int, int_base+hyphen_penalty_code);@/ -@!@:hyphen\_penalty\_}{\.{\\hyphenpenalty} primitive@> -primitive("exhyphenpenalty", assign_int, int_base+ex_hyphen_penalty_code);@/ -@!@:ex\_hyphen\_penalty\_}{\.{\\exhyphenpenalty} primitive@> -primitive("clubpenalty", assign_int, int_base+club_penalty_code);@/ -@!@:club\_penalty\_}{\.{\\clubpenalty} primitive@> -primitive("widowpenalty", assign_int, int_base+widow_penalty_code);@/ -@!@:widow\_penalty\_}{\.{\\widowpenalty} primitive@> -primitive("displaywidowpenalty", - assign_int, int_base+display_widow_penalty_code);@/ -@!@:display\_widow\_penalty\_}{\.{\\displaywidowpenalty} primitive@> -primitive("brokenpenalty", assign_int, int_base+broken_penalty_code);@/ -@!@:broken\_penalty\_}{\.{\\brokenpenalty} primitive@> -primitive("binoppenalty", assign_int, int_base+bin_op_penalty_code);@/ -@!@:bin\_op\_penalty\_}{\.{\\binoppenalty} primitive@> -primitive("relpenalty", assign_int, int_base+rel_penalty_code);@/ -@!@:rel\_penalty\_}{\.{\\relpenalty} primitive@> -primitive("predisplaypenalty", assign_int, int_base+pre_display_penalty_code);@/ -@!@:pre\_display\_penalty\_}{\.{\\predisplaypenalty} primitive@> -primitive("postdisplaypenalty", assign_int, int_base+post_display_penalty_code);@/ -@!@:post\_display\_penalty\_}{\.{\\postdisplaypenalty} primitive@> -primitive("interlinepenalty", assign_int, int_base+inter_line_penalty_code);@/ -@!@:inter\_line\_penalty\_}{\.{\\interlinepenalty} primitive@> -primitive("doublehyphendemerits", - assign_int, int_base+double_hyphen_demerits_code);@/ -@!@:double\_hyphen\_demerits\_}{\.{\\doublehyphendemerits} primitive@> -primitive("finalhyphendemerits", - assign_int, int_base+final_hyphen_demerits_code);@/ -@!@:final\_hyphen\_demerits\_}{\.{\\finalhyphendemerits} primitive@> -primitive("adjdemerits", assign_int, int_base+adj_demerits_code);@/ -@!@:adj\_demerits\_}{\.{\\adjdemerits} primitive@> -primitive("mag", assign_int, int_base+mag_code);@/ -@!@:mag\_}{\.{\\mag} primitive@> -primitive("delimiterfactor", assign_int, int_base+delimiter_factor_code);@/ -@!@:delimiter\_factor\_}{\.{\\delimiterfactor} primitive@> -primitive("looseness", assign_int, int_base+looseness_code);@/ -@!@:looseness\_}{\.{\\looseness} primitive@> -primitive("time", assign_int, int_base+time_code);@/ -@!@:time\_}{\.{\\time} primitive@> -primitive("day", assign_int, int_base+day_code);@/ -@!@:day\_}{\.{\\day} primitive@> -primitive("month", assign_int, int_base+month_code);@/ -@!@:month\_}{\.{\\month} primitive@> -primitive("year", assign_int, int_base+year_code);@/ -@!@:year\_}{\.{\\year} primitive@> -primitive("showboxbreadth", assign_int, int_base+show_box_breadth_code);@/ -@!@:show\_box\_breadth\_}{\.{\\showboxbreadth} primitive@> -primitive("showboxdepth", assign_int, int_base+show_box_depth_code);@/ -@!@:show\_box\_depth\_}{\.{\\showboxdepth} primitive@> -primitive("hbadness", assign_int, int_base+hbadness_code);@/ -@!@:hbadness\_}{\.{\\hbadness} primitive@> -primitive("vbadness", assign_int, int_base+vbadness_code);@/ -@!@:vbadness\_}{\.{\\vbadness} primitive@> -primitive("pausing", assign_int, int_base+pausing_code);@/ -@!@:pausing\_}{\.{\\pausing} primitive@> -primitive("tracingonline", assign_int, int_base+tracing_online_code);@/ -@!@:tracing\_online\_}{\.{\\tracingonline} primitive@> -primitive("tracingmacros", assign_int, int_base+tracing_macros_code);@/ -@!@:tracing\_macros\_}{\.{\\tracingmacros} primitive@> -primitive("tracingstats", assign_int, int_base+tracing_stats_code);@/ -@!@:tracing\_stats\_}{\.{\\tracingstats} primitive@> -primitive("tracingparagraphs", assign_int, int_base+tracing_paragraphs_code);@/ -@!@:tracing\_paragraphs\_}{\.{\\tracingparagraphs} primitive@> -primitive("tracingpages", assign_int, int_base+tracing_pages_code);@/ -@!@:tracing\_pages\_}{\.{\\tracingpages} primitive@> -primitive("tracingoutput", assign_int, int_base+tracing_output_code);@/ -@!@:tracing\_output\_}{\.{\\tracingoutput} primitive@> -primitive("tracinglostchars", assign_int, int_base+tracing_lost_chars_code);@/ -@!@:tracing\_lost\_chars\_}{\.{\\tracinglostchars} primitive@> -primitive("tracingcommands", assign_int, int_base+tracing_commands_code);@/ -@!@:tracing\_commands\_}{\.{\\tracingcommands} primitive@> -primitive("tracingrestores", assign_int, int_base+tracing_restores_code);@/ -@!@:tracing\_restores\_}{\.{\\tracingrestores} primitive@> -primitive("uchyph", assign_int, int_base+uc_hyph_code);@/ -@!@:uc\_hyph\_}{\.{\\uchyph} primitive@> -primitive("outputpenalty", assign_int, int_base+output_penalty_code);@/ -@!@:output\_penalty\_}{\.{\\outputpenalty} primitive@> -primitive("maxdeadcycles", assign_int, int_base+max_dead_cycles_code);@/ -@!@:max\_dead\_cycles\_}{\.{\\maxdeadcycles} primitive@> -primitive("hangafter", assign_int, int_base+hang_after_code);@/ -@!@:hang\_after\_}{\.{\\hangafter} primitive@> -primitive("floatingpenalty", assign_int, int_base+floating_penalty_code);@/ -@!@:floating\_penalty\_}{\.{\\floatingpenalty} primitive@> -primitive("globaldefs", assign_int, int_base+global_defs_code);@/ -@!@:global\_defs\_}{\.{\\globaldefs} primitive@> -primitive("fam", assign_int, int_base+cur_fam_code);@/ -@!@:fam\_}{\.{\\fam} primitive@> -primitive("escapechar", assign_int, int_base+escape_char_code);@/ -@!@:escape\_char\_}{\.{\\escapechar} primitive@> -primitive("defaulthyphenchar", assign_int, int_base+default_hyphen_char_code);@/ -@!@:default\_hyphen\_char\_}{\.{\\defaulthyphenchar} primitive@> -primitive("defaultskewchar", assign_int, int_base+default_skew_char_code);@/ -@!@:default\_skew\_char\_}{\.{\\defaultskewchar} primitive@> -primitive("endlinechar", assign_int, int_base+end_line_char_code);@/ -@!@:end\_line\_char\_}{\.{\\endlinechar} primitive@> -primitive("newlinechar", assign_int, int_base+new_line_char_code);@/ -@!@:new\_line\_char\_}{\.{\\newlinechar} primitive@> -primitive("language", assign_int, int_base+language_code);@/ -@!@:language\_}{\.{\\language} primitive@> -primitive("lefthyphenmin", assign_int, int_base+left_hyphen_min_code);@/ -@!@:left\_hyphen\_min\_}{\.{\\lefthyphenmin} primitive@> -primitive("righthyphenmin", assign_int, int_base+right_hyphen_min_code);@/ -@!@:right\_hyphen\_min\_}{\.{\\righthyphenmin} primitive@> -primitive("holdinginserts", assign_int, int_base+holding_inserts_code);@/ -@!@:holding\_inserts\_}{\.{\\holdinginserts} primitive@> -primitive("errorcontextlines", assign_int, int_base+error_context_lines_code);@/ -@!@:error\_context\_lines\_}{\.{\\errorcontextlines} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case assign_int: if (chr_code < count_base) print_param(chr_code-int_base); - else{@+print_esc("count");print_int(chr_code-count_base); - } @+break; - -@ The integer parameters should really be initialized by a macro package; -the following initialization does the minimum to keep \TeX\ from -complete failure. -@^null delimiter@> - -@<Initialize table entries...@>= -for (k=int_base; k<=del_code_base-1; k++) eqtb[k].i=0; -mag=1000;tolerance=10000;hang_after=1;max_dead_cycles=25; -escape_char='\\';end_line_char=carriage_return; -for (k=0; k<=255; k++) del_code(k)=-1; -del_code('.')=0; /*this null delimiter is used in error recovery*/ - -@ The following procedure, which is called just before \TeX\ initializes its -input and output, establishes the initial values of the date and time. -@^system dependencies@> -k\TeX\ calls |tl_now| to obtain the current time as a |tm| structure. -@p static void fix_date_and_time(void) -{@+struct tm *gmt=tl_now(); - time=sys_time= gmt->tm_hour*60+gmt->tm_min;/*minutes since midnight*/ - day=sys_day= gmt->tm_mday;/*day of the month*/ - month=sys_month=gmt->tm_mon+1;/*month of the year*/ - year=sys_year=gmt->tm_year+1900;/*Anno Domini*/ -} - -@ @<Show equivalent |n|, in region 5@>= -{@+if (n < count_base) print_param(n-int_base); -else if (n < del_code_base) - {@+print_esc("count");print_int(n-count_base); - } -else{@+print_esc("delcode");print_int(n-del_code_base); - } -print_char('=');print_int(eqtb[n].i); -} - -@ @<Set variable |c| to the current escape character@>=c=escape_char - -@ @<Character |s| is the current new-line character@>=s==new_line_char - -@ \TeX\ is occasionally supposed to print diagnostic information that -goes only into the transcript file, unless |tracing_online| is positive. -Here are two routines that adjust the destination of print commands: - -@p void begin_diagnostic(void) /*prepare to do some tracing*/ -{@+old_setting=selector; -if ((tracing_online <= 0)&&(selector==term_and_log)) - {@+decr(selector); - if (history==spotless) history=warning_issued; - } -} -@# -void end_diagnostic(bool @!blank_line) - /*restore proper conditions after tracing*/ -{@+print_nl(""); -if (blank_line) print_ln(); -selector=old_setting; -} - -@ Of course we had better declare a few more global variables, if the previous -routines are going to work. - -@<Glob...@>= -static int @!old_setting; -static int @!sys_time, @!sys_day, @!sys_month, @!sys_year; - /*date and time supplied by external system*/ - -@ The final region of |eqtb| contains the dimension parameters defined -here, and the 256 \.{\\dimen} registers. - -@d par_indent_code 0 /*indentation of paragraphs*/ -@d math_surround_code 1 /*space around math in text*/ -@d line_skip_limit_code 2 /*threshold for |line_skip| instead of |baseline_skip|*/ -@d hsize_code 3 /*line width in horizontal mode*/ -@d vsize_code 4 /*page height in vertical mode*/ -@d max_depth_code 5 /*maximum depth of boxes on main pages*/ -@d split_max_depth_code 6 /*maximum depth of boxes on split pages*/ -@d box_max_depth_code 7 /*maximum depth of explicit vboxes*/ -@d hfuzz_code 8 /*tolerance for overfull hbox messages*/ -@d vfuzz_code 9 /*tolerance for overfull vbox messages*/ -@d delimiter_shortfall_code 10 /*maximum amount uncovered by variable delimiters*/ -@d null_delimiter_space_code 11 /*blank space in null delimiters*/ -@d script_space_code 12 /*extra space after subscript or superscript*/ -@d pre_display_size_code 13 /*length of text preceding a display*/ -@d display_width_code 14 /*length of line for displayed equation*/ -@d display_indent_code 15 /*indentation of line for displayed equation*/ -@d overfull_rule_code 16 /*width of rule that identifies overfull hboxes*/ -@d hang_indent_code 17 /*amount of hanging indentation*/ -@d h_offset_code 18 /*amount of horizontal offset when shipping pages out*/ -@d v_offset_code 19 /*amount of vertical offset when shipping pages out*/ -@d emergency_stretch_code 20 /*reduces badnesses on final pass of line-breaking*/ -@d dimen_pars 21 /*total number of dimension parameters*/ -@d scaled_base (dimen_base+dimen_pars) - /*table of 256 user-defined \.{\\dimen} registers*/ -@d eqtb_size (scaled_base+255) /*largest subscript of |eqtb|*/ -@# -@d dimen(A) eqtb[scaled_base+A].sc -@d dimen_par(A) eqtb[dimen_base+A].sc /*a scaled quantity*/ -@d dimen_hfactor(A) hfactor_eqtb[scaled_base+A].sc -@d dimen_vfactor(A) vfactor_eqtb[scaled_base+A].sc -@d dimen_par_hfactor(A) hfactor_eqtb[dimen_base+A].sc -@d dimen_par_vfactor(A) vfactor_eqtb[dimen_base+A].sc -@d par_indent dimen_par(par_indent_code) -@d math_surround dimen_par(math_surround_code) -@d line_skip_limit dimen_par(line_skip_limit_code) -@d hsize dimen_par(hsize_code) -@d vsize dimen_par(vsize_code) -@d max_depth dimen_par(max_depth_code) -@d split_max_depth dimen_par(split_max_depth_code) -@d box_max_depth dimen_par(box_max_depth_code) -@d hfuzz dimen_par(hfuzz_code) -@d vfuzz dimen_par(vfuzz_code) -@d delimiter_shortfall dimen_par(delimiter_shortfall_code) -@d null_delimiter_space dimen_par(null_delimiter_space_code) -@d script_space dimen_par(script_space_code) -@d pre_display_size dimen_par(pre_display_size_code) -@d display_width dimen_par(display_width_code) -@d display_indent dimen_par(display_indent_code) -@d overfull_rule dimen_par(overfull_rule_code) -@d hang_indent dimen_par(hang_indent_code) -@d h_offset dimen_par(h_offset_code) -@d v_offset dimen_par(v_offset_code) -@d emergency_stretch dimen_par(emergency_stretch_code) - -@p static void print_length_param(int @!n) -{@+switch (n) { -case par_indent_code: print_esc("parindent");@+break; -case math_surround_code: print_esc("mathsurround");@+break; -case line_skip_limit_code: print_esc("lineskiplimit");@+break; -case hsize_code: print_esc("hsize");@+break; -case vsize_code: print_esc("vsize");@+break; -case max_depth_code: print_esc("maxdepth");@+break; -case split_max_depth_code: print_esc("splitmaxdepth");@+break; -case box_max_depth_code: print_esc("boxmaxdepth");@+break; -case hfuzz_code: print_esc("hfuzz");@+break; -case vfuzz_code: print_esc("vfuzz");@+break; -case delimiter_shortfall_code: print_esc("delimitershortfall");@+break; -case null_delimiter_space_code: print_esc("nulldelimiterspace");@+break; -case script_space_code: print_esc("scriptspace");@+break; -case pre_display_size_code: print_esc("predisplaysize");@+break; -case display_width_code: print_esc("displaywidth");@+break; -case display_indent_code: print_esc("displayindent");@+break; -case overfull_rule_code: print_esc("overfullrule");@+break; -case hang_indent_code: print_esc("hangindent");@+break; -case h_offset_code: print_esc("hoffset");@+break; -case v_offset_code: print_esc("voffset");@+break; -case emergency_stretch_code: print_esc("emergencystretch");@+break; -default:print("[unknown dimen parameter!]"); -} -} - -@ @<Put each...@>= -primitive("parindent", assign_dimen, dimen_base+par_indent_code);@/ -@!@:par\_indent\_}{\.{\\parindent} primitive@> -primitive("mathsurround", assign_dimen, dimen_base+math_surround_code);@/ -@!@:math\_surround\_}{\.{\\mathsurround} primitive@> -primitive("lineskiplimit", assign_dimen, dimen_base+line_skip_limit_code);@/ -@!@:line\_skip\_limit\_}{\.{\\lineskiplimit} primitive@> -primitive("hsize", assign_dimen, dimen_base+hsize_code);@/ -@!@:hsize\_}{\.{\\hsize} primitive@> -primitive("vsize", assign_dimen, dimen_base+vsize_code);@/ -@!@:vsize\_}{\.{\\vsize} primitive@> -primitive("maxdepth", assign_dimen, dimen_base+max_depth_code);@/ -@!@:max\_depth\_}{\.{\\maxdepth} primitive@> -primitive("splitmaxdepth", assign_dimen, dimen_base+split_max_depth_code);@/ -@!@:split\_max\_depth\_}{\.{\\splitmaxdepth} primitive@> -primitive("boxmaxdepth", assign_dimen, dimen_base+box_max_depth_code);@/ -@!@:box\_max\_depth\_}{\.{\\boxmaxdepth} primitive@> -primitive("hfuzz", assign_dimen, dimen_base+hfuzz_code);@/ -@!@:hfuzz\_}{\.{\\hfuzz} primitive@> -primitive("vfuzz", assign_dimen, dimen_base+vfuzz_code);@/ -@!@:vfuzz\_}{\.{\\vfuzz} primitive@> -primitive("delimitershortfall", - assign_dimen, dimen_base+delimiter_shortfall_code);@/ -@!@:delimiter\_shortfall\_}{\.{\\delimitershortfall} primitive@> -primitive("nulldelimiterspace", - assign_dimen, dimen_base+null_delimiter_space_code);@/ -@!@:null\_delimiter\_space\_}{\.{\\nulldelimiterspace} primitive@> -primitive("scriptspace", assign_dimen, dimen_base+script_space_code);@/ -@!@:script\_space\_}{\.{\\scriptspace} primitive@> -primitive("predisplaysize", assign_dimen, dimen_base+pre_display_size_code);@/ -@!@:pre\_display\_size\_}{\.{\\predisplaysize} primitive@> -primitive("displaywidth", assign_dimen, dimen_base+display_width_code);@/ -@!@:display\_width\_}{\.{\\displaywidth} primitive@> -primitive("displayindent", assign_dimen, dimen_base+display_indent_code);@/ -@!@:display\_indent\_}{\.{\\displayindent} primitive@> -primitive("overfullrule", assign_dimen, dimen_base+overfull_rule_code);@/ -@!@:overfull\_rule\_}{\.{\\overfullrule} primitive@> -primitive("hangindent", assign_dimen, dimen_base+hang_indent_code);@/ -@!@:hang\_indent\_}{\.{\\hangindent} primitive@> -primitive("hoffset", assign_dimen, dimen_base+h_offset_code);@/ -@!@:h\_offset\_}{\.{\\hoffset} primitive@> -primitive("voffset", assign_dimen, dimen_base+v_offset_code);@/ -@!@:v\_offset\_}{\.{\\voffset} primitive@> -primitive("emergencystretch", assign_dimen, dimen_base+emergency_stretch_code);@/ -@!@:emergency\_stretch\_}{\.{\\emergencystretch} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case assign_dimen: if (chr_code < scaled_base) - print_length_param(chr_code-dimen_base); - else{@+print_esc("dimen");print_int(chr_code-scaled_base); - } @+break; - -@ @<Initialize table entries...@>= -for (k=dimen_base; k<=eqtb_size; k++) hfactor_eqtb[k].sc=vfactor_eqtb[k].sc=eqtb[k].sc=0; - -@ @<Show equivalent |n|, in region 6@>= -{@+if (n < scaled_base) print_length_param(n-dimen_base); -else{@+print_esc("dimen");print_int(n-scaled_base); - } -print_char('=');print_scaled(eqtb[n].sc);print("pt"); -} - -@ Here is a procedure that displays the contents of |eqtb[n]| -symbolically. - -@p @t\4@>@<Declare the procedure called |print_cmd_chr|@>@;@/ -#ifdef @!STAT -static void show_eqtb(pointer @!n) -{@+if (n < active_base) print_char('?'); /*this can't happen*/ -else if (n < glue_base) @<Show equivalent |n|, in region 1 or 2@>@; -else if (n < local_base) @<Show equivalent |n|, in region 3@>@; -else if (n < int_base) @<Show equivalent |n|, in region 4@>@; -else if (n < dimen_base) @<Show equivalent |n|, in region 5@>@; -else if (n <= eqtb_size) @<Show equivalent |n|, in region 6@>@; -else print_char('?'); /*this can't happen either*/ -} -#endif - -@ The last two regions of |eqtb| have fullword values instead of the -three fields |eq_level|, |eq_type|, and |equiv|. An |eq_type| is unnecessary, -but \TeX\ needs to store the |eq_level| information in another array -called |xeq_level|. - -@<Glob...@>= -memory_word @!eqtb0[eqtb_size-active_base+1], *const @!eqtb = @!eqtb0-active_base; -memory_word hfactor_eqtb0[dimen_pars+256]={{{0}}}, *const @!hfactor_eqtb = @!hfactor_eqtb0-dimen_base; -memory_word vfactor_eqtb0[dimen_pars+256]={{{0}}}, *const @!vfactor_eqtb = @!vfactor_eqtb0-dimen_base; -scaled par_shape_hfactor=0, par_shape_vfactor=0; -scaled hhsize=0,hvsize=0; -static quarterword @!xeq_level0[eqtb_size-int_base+1], *const @!xeq_level = @!xeq_level0-int_base; - -@ @<Set init...@>= -for (k=int_base; k<=eqtb_size; k++) xeq_level[k]=level_one; - -@ When the debugging routine |search_mem| is looking for pointers having a -given value, it is interested only in regions 1 to~3 of~|eqtb|, and in the -first part of region~4. - -@<Search |eqtb| for equivalents equal to |p|@>= -for (q=active_base; q<=box_base+255; q++) - {@+if (equiv(q)==p) - {@+print_nl("EQUIV(");print_int(q);print_char(')'); - } - } - -@* The hash table. -Control sequences are stored and retrieved by means of a fairly standard hash -table algorithm called the method of ``coalescing lists'' (cf.\ Algorithm 6.4C -in {\sl The Art of Computer Programming\/}). Once a control sequence enters the -table, it is never removed, because there are complicated situations -involving \.{\\gdef} where the removal of a control sequence at the end of -a group would be a mistake preventable only by the introduction of a -complicated reference-count mechanism. - -The actual sequence of letters forming a control sequence identifier is -stored in the |str_pool| array together with all the other strings. An -auxiliary array |hash| consists of items with two halfword fields per -word. The first of these, called |next(p)|, points to the next identifier -belonging to the same coalesced list as the identifier corresponding to~|p|; -and the other, called |text(p)|, points to the |str_start| entry for -|p|'s identifier. If position~|p| of the hash table is empty, we have -|text(p)==0|; if position |p| is either empty or the end of a coalesced -hash list, we have |next(p)==0|. An auxiliary pointer variable called -|hash_used| is maintained in such a way that all locations |p >= hash_used| -are nonempty. The global variable |cs_count| tells how many multiletter -control sequences have been defined, if statistics are being kept. - -A global boolean variable called |no_new_control_sequence| is set to -|true| during the time that new hash table entries are forbidden. - -@d next(A) hash[A].lh /*link for coalesced lists*/ -@d text(A) hash[A].rh /*string number for control sequence name*/ -@d hash_is_full (hash_used==hash_base) /*test if all positions are occupied*/ -@d font_id_text(A) text(font_id_base+A) /*a frozen font identifier's name*/ - -@<Glob...@>= -two_halves @!hash0[undefined_control_sequence-hash_base], *const @!hash = @!hash0-hash_base; - /*the hash table*/ -static pointer @!hash_used; /*allocation pointer for |hash|*/ -static bool @!no_new_control_sequence; /*are new identifiers legal?*/ -static int @!cs_count; /*total number of known identifiers*/ - -@ @<Set init...@>= -no_new_control_sequence=true; /*new identifiers are usually forbidden*/ -next(hash_base)=0;text(hash_base)=0; -for (k=hash_base+1; k<=undefined_control_sequence-1; k++) hash[k]=hash[hash_base]; - -@ @<Initialize table entries...@>= -hash_used=frozen_control_sequence; /*nothing is used*/ -cs_count=0; -eq_type(frozen_dont_expand)=dont_expand; -text(frozen_dont_expand)=s_no("notexpanded:"); -@.notexpanded:@> - -@ Here is the subroutine that searches the hash table for an identifier -that matches a given string of length |l > 1| appearing in |buffer[j dotdot -(j+l-1)]|. If the identifier is found, the corresponding hash table address -is returned. Otherwise, if the global variable |no_new_control_sequence| -is |true|, the dummy address |undefined_control_sequence| is returned. -Otherwise the identifier is inserted into the hash table and its location -is returned. - -@p static pointer id_lookup(int @!j, int @!l) /*search the hash table*/ -{@+ /*go here if you found it*/ -int h; /*hash code*/ -int @!d; /*number of characters in incomplete current string*/ -pointer @!p; /*index in |hash| array*/ -int @!k; /*index in |buffer| array*/ -@<Compute the hash code |h|@>; -p=h+hash_base; /*we start searching here; note that |0 <= h < hash_prime|*/ -loop@+{@+if (text(p) > 0) if (length(text(p))==l) - if (str_eq_buf(text(p), j)) goto found; - if (next(p)==0) - {@+if (no_new_control_sequence) - p=undefined_control_sequence; - else@<Insert a new control sequence after |p|, then make |p| point to it@>; - goto found; - } - p=next(p); - } -found: return p; -} - -@ @<Insert a new control...@>= -{@+if (text(p) > 0) - {@+@/do@+{if (hash_is_full) overflow("hash size", hash_size); -@:TeX capacity exceeded hash size}{\quad hash size@> - decr(hash_used); - }@+ while (!(text(hash_used)==0)); /*search for an empty location in |hash|*/ - next(p)=hash_used;p=hash_used; - } -str_room(l);d=cur_length; -while (pool_ptr > str_start[str_ptr]) - {@+decr(pool_ptr);str_pool[pool_ptr+l]=str_pool[pool_ptr]; - } /*move current string up to make room for another*/ -for (k=j; k<=j+l-1; k++) append_char(buffer[k]); -text(p)=make_string();pool_ptr=pool_ptr+d; -#ifdef @!STAT -incr(cs_count); -#endif -@;@/ -} - -@ The value of |hash_prime| should be roughly 85\pct! of |hash_size|, and it -should be a prime number. The theory of hashing tells us to expect fewer -than two table probes, on the average, when the search is successful. -[See J.~S. Vitter, {\sl Journal of the ACM\/ \bf30} (1983), 231--258.] -@^Vitter, Jeffrey Scott@> - -@<Compute the hash code |h|@>= -h=buffer[j]; -for (k=j+1; k<=j+l-1; k++) - {@+h=h+h+buffer[k]; - while (h >= hash_prime) h=h-hash_prime; - } - -@ Single-character control sequences do not need to be looked up in a hash -table, since we can use the character code itself as a direct address. -The procedure |print_cs| prints the name of a control sequence, given -a pointer to its address in |eqtb|. A space is printed after the name -unless it is a single nonletter or an active character. This procedure -might be invoked with invalid data, so it is ``extra robust.'' The -individual characters must be printed one at a time using |print|, since -they may be unprintable. - -@<Basic printing...@>= -static void print_cs(int @!p) /*prints a purported control sequence*/ -{@+if (p < hash_base) /*single character*/ - if (p >= single_base) - if (p==null_cs) - {@+print_esc("csname");print_esc("endcsname");print_char(' '); - } - else{@+printn_esc(p-single_base); - if (cat_code(p-single_base)==letter) print_char(' '); - } - else if (p < active_base) print_esc("IMPOSSIBLE."); -@.IMPOSSIBLE@> - else printn(p-active_base); -else if (p >= undefined_control_sequence) print_esc("IMPOSSIBLE."); -else if ((text(p) < 0)||(text(p) >= str_ptr)) print_esc("NONEXISTENT."); -@.NONEXISTENT@> -else{@+printn_esc(text(p)); - print_char(' '); - } -} - -@ Here is a similar procedure; it avoids the error checks, and it never -prints a space after the control sequence. - -@<Basic printing procedures@>= -static void sprint_cs(pointer @!p) /*prints a control sequence*/ -{@+if (p < hash_base) - if (p < single_base) printn(p-active_base); - else if (p < null_cs) printn_esc(p-single_base); - else{@+print_esc("csname");print_esc("endcsname"); - } -else printn_esc(text(p)); -} - -@ We need to put \TeX's ``primitive'' control sequences into the hash -table, together with their command code (which will be the |eq_type|) -and an operand (which will be the |equiv|). The |primitive| procedure -does this, in a way that no \TeX\ user can. The global value |cur_val| -contains the new |eqtb| pointer after |primitive| has acted. - -@p -#ifdef @!INIT -static void primitive(char *@!str, quarterword @!c, halfword @!o) -{@+str_number s=s_no(str); -int k; /*index into |str_pool|*/ -int @!j; /*index into |buffer|*/ -small_number @!l; /*length of the string*/ -if (s < 256) cur_val=s+single_base; -else{@+k=str_start[s];l=str_start[s+1]-k; - /*we will move |s| into the (possibly non-empty) |buffer|*/ - if (first+l > buf_size+1) - overflow("buffer size", buf_size); -@:TeX capacity exceeded buffer size}{\quad buffer size@> - for (j=0; j<=l-1; j++) buffer[first+j]=so(str_pool[k+j]); - cur_val=id_lookup(first, l); /*|no_new_control_sequence| is |false|*/ - flush_string;text(cur_val)=s; /*we don't want to have the string twice*/ - } -eq_level(cur_val)=level_one;eq_type(cur_val)=c;equiv(cur_val)=o; -} -#endif - -@ Many of \TeX's primitives need no |equiv|, since they are identifiable -by their |eq_type| alone. These primitives are loaded into the hash table -as follows: - -@<Put each of \TeX's primitives into the hash table@>= -primitive(" ", ex_space, 0);@/ -@!@:Single-character primitives /}{\quad\.{\\\ }@> -primitive("/", ital_corr, 0);@/ -@!@:Single-character primitives /}{\quad\.{\\/}@> -primitive("accent", accent, 0);@/ -@!@:accent\_}{\.{\\accent} primitive@> -primitive("advance", advance, 0);@/ -@!@:advance\_}{\.{\\advance} primitive@> -primitive("afterassignment", after_assignment, 0);@/ -@!@:after\_assignment\_}{\.{\\afterassignment} primitive@> -primitive("aftergroup", after_group, 0);@/ -@!@:after\_group\_}{\.{\\aftergroup} primitive@> -primitive("begingroup", begin_group, 0);@/ -@!@:begin\_group\_}{\.{\\begingroup} primitive@> -primitive("char", char_num, 0);@/ -@!@:char\_}{\.{\\char} primitive@> -primitive("csname", cs_name, 0);@/ -@!@:cs\_name\_}{\.{\\csname} primitive@> -primitive("delimiter", delim_num, 0);@/ -@!@:delimiter\_}{\.{\\delimiter} primitive@> -primitive("divide", divide, 0);@/ -@!@:divide\_}{\.{\\divide} primitive@> -primitive("endcsname", end_cs_name, 0);@/ -@!@:end\_cs\_name\_}{\.{\\endcsname} primitive@> -primitive("endgroup", end_group, 0); -@!@:end\_group\_}{\.{\\endgroup} primitive@> -text(frozen_end_group)=text(cur_val);eqtb[frozen_end_group]=eqtb[cur_val];@/ -primitive("expandafter", expand_after, 0);@/ -@!@:expand\_after\_}{\.{\\expandafter} primitive@> -primitive("font", def_font, 0);@/ -@!@:font\_}{\.{\\font} primitive@> -primitive("fontdimen", assign_font_dimen, 0);@/ -@!@:font\_dimen\_}{\.{\\fontdimen} primitive@> -primitive("halign", halign, 0);@/ -@!@:halign\_}{\.{\\halign} primitive@> -primitive("hrule", hrule, 0);@/ -@!@:hrule\_}{\.{\\hrule} primitive@> -primitive("ignorespaces", ignore_spaces, 0);@/ -@!@:ignore\_spaces\_}{\.{\\ignorespaces} primitive@> -primitive("insert", insert, 0);@/ -@!@:insert\_}{\.{\\insert} primitive@> -primitive("mark", mark, 0);@/ -@!@:mark\_}{\.{\\mark} primitive@> -primitive("mathaccent", math_accent, 0);@/ -@!@:math\_accent\_}{\.{\\mathaccent} primitive@> -primitive("mathchar", math_char_num, 0);@/ -@!@:math\_char\_}{\.{\\mathchar} primitive@> -primitive("mathchoice", math_choice, 0);@/ -@!@:math\_choice\_}{\.{\\mathchoice} primitive@> -primitive("multiply", multiply, 0);@/ -@!@:multiply\_}{\.{\\multiply} primitive@> -primitive("noalign", no_align, 0);@/ -@!@:no\_align\_}{\.{\\noalign} primitive@> -primitive("noboundary", no_boundary, 0);@/ -@!@:no\_boundary\_}{\.{\\noboundary} primitive@> -primitive("noexpand", no_expand, 0);@/ -@!@:no\_expand\_}{\.{\\noexpand} primitive@> -primitive("nonscript", non_script, 0);@/ -@!@:non\_script\_}{\.{\\nonscript} primitive@> -primitive("omit", omit, 0);@/ -@!@:omit\_}{\.{\\omit} primitive@> -primitive("parshape", set_shape, par_shape_loc);@/ -@!@:par\_shape\_}{\.{\\parshape} primitive@> -primitive("penalty", break_penalty, 0);@/ -@!@:penalty\_}{\.{\\penalty} primitive@> -primitive("prevgraf", set_prev_graf, 0);@/ -@!@:prev\_graf\_}{\.{\\prevgraf} primitive@> -primitive("radical", radical, 0);@/ -@!@:radical\_}{\.{\\radical} primitive@> -primitive("read", read_to_cs, 0);@/ -@!@:read\_}{\.{\\read} primitive@> -primitive("relax", relax, 256); /*cf.\ |scan_file_name|*/ -@!@:relax\_}{\.{\\relax} primitive@> -text(frozen_relax)=text(cur_val);eqtb[frozen_relax]=eqtb[cur_val];@/ -primitive("setbox", set_box, 0);@/ -@!@:set\_box\_}{\.{\\setbox} primitive@> -primitive("the", the, 0);@/ -@!@:the\_}{\.{\\the} primitive@> -primitive("toks", toks_register, mem_bot);@/ -@!@:toks\_}{\.{\\toks} primitive@> -primitive("vadjust", vadjust, 0);@/ -@!@:vadjust\_}{\.{\\vadjust} primitive@> -primitive("valign", valign, 0);@/ -@!@:valign\_}{\.{\\valign} primitive@> -primitive("vcenter", vcenter, 0);@/ -@!@:vcenter\_}{\.{\\vcenter} primitive@> -primitive("vrule", vrule, 0);@/ -@!@:vrule\_}{\.{\\vrule} primitive@> - -@ Each primitive has a corresponding inverse, so that it is possible to -display the cryptic numeric contents of |eqtb| in symbolic form. -Every call of |primitive| in this program is therefore accompanied by some -straightforward code that forms part of the |print_cmd_chr| routine -below. - -@<Cases of |print_cmd_chr|...@>= -case accent: print_esc("accent");@+break; -case advance: print_esc("advance");@+break; -case after_assignment: print_esc("afterassignment");@+break; -case after_group: print_esc("aftergroup");@+break; -case assign_font_dimen: print_esc("fontdimen");@+break; -case begin_group: print_esc("begingroup");@+break; -case break_penalty: print_esc("penalty");@+break; -case char_num: print_esc("char");@+break; -case cs_name: print_esc("csname");@+break; -case def_font: print_esc("font");@+break; -case delim_num: print_esc("delimiter");@+break; -case divide: print_esc("divide");@+break; -case end_cs_name: print_esc("endcsname");@+break; -case end_group: print_esc("endgroup");@+break; -case ex_space: print_esc(" ");@+break; -case expand_after: if (chr_code==0) print_esc("expandafter") - @<Cases of |expandafter| for |print_cmd_chr|@>;@+break; -case halign: print_esc("halign");@+break; -case hrule: print_esc("hrule");@+break; -case ignore_spaces: print_esc("ignorespaces");@+break; -case insert: print_esc("insert");@+break; -case ital_corr: print_esc("/");@+break; -case mark: print_esc("mark");@+break; -case math_accent: print_esc("mathaccent");@+break; -case math_char_num: print_esc("mathchar");@+break; -case math_choice: print_esc("mathchoice");@+break; -case multiply: print_esc("multiply");@+break; -case no_align: print_esc("noalign");@+break; -case no_boundary: print_esc("noboundary");@+break; -case no_expand: print_esc("noexpand");@+break; -case non_script: print_esc("nonscript");@+break; -case omit: print_esc("omit");@+break; -case radical: print_esc("radical");@+break; -case read_to_cs: if (chr_code==0) print_esc("read") - @<Cases of |read| for |print_cmd_chr|@>;@+break; -case relax: print_esc("relax");@+break; -case set_box: print_esc("setbox");@+break; -case set_prev_graf: print_esc("prevgraf");@+break; -case set_shape: switch (chr_code) { - case par_shape_loc: print_esc("parshape");@+break; - @<Cases of |set_shape| for |print_cmd_chr|@>@;@/ - } @+break; /*there are no other cases*/ -case the: if (chr_code==0) print_esc("the") - @<Cases of |the| for |print_cmd_chr|@>;@+break; -case toks_register: @<Cases of |toks_register| for |print_cmd_chr|@>@;@+break; -case vadjust: print_esc("vadjust");@+break; -case valign: print_esc("valign");@+break; -case vcenter: print_esc("vcenter");@+break; -case vrule: print_esc("vrule");@+break; - -@ We will deal with the other primitives later, at some point in the program -where their |eq_type| and |equiv| values are more meaningful. For example, -the primitives for math mode will be loaded when we consider the routines -that deal with formulas. It is easy to find where each particular -primitive was treated by looking in the index at the end; for example, the -section where |"radical"| entered |eqtb| is listed under `\.{\\radical} -primitive'. (Primitives consisting of a single nonalphabetic character, -@!like `\.{\\/}', are listed under `Single-character primitives'.) -@!@^Single-character primitives@> - -Meanwhile, this is a convenient place to catch up on something we were unable -to do before the hash table was defined: - -@<Print the font identifier for |font(p)|@>= -printn_esc(font_id_text(font(p))) - -@* Saving and restoring equivalents. -The nested structure provided by `$\.{\char'173}\ldots\.{\char'175}$' groups -in \TeX\ means that |eqtb| entries valid in outer groups should be saved -and restored later if they are overridden inside the braces. When a new |eqtb| -value is being assigned, the program therefore checks to see if the previous -entry belongs to an outer level. In such a case, the old value is placed -on the |save_stack| just before the new value enters |eqtb|. At the -end of a grouping level, i.e., when the right brace is sensed, the -|save_stack| is used to restore the outer values, and the inner ones are -destroyed. - -Entries on the |save_stack| are of type |memory_word|. The top item on -this stack is |save_stack[p]|, where |p==save_ptr-1|; it contains three -fields called |save_type|, |save_level|, and |save_index|, and it is -interpreted in one of five ways: - -\yskip\hangg 1) If |save_type(p)==restore_old_value|, then -|save_index(p)| is a location in |eqtb| whose current value should -be destroyed at the end of the current group and replaced by |save_stack[p-1]|. -Furthermore if |save_index(p) >= int_base|, then |save_level(p)| -should replace the corresponding entry in |xeq_level|. - -\yskip\hangg 2) If |save_type(p)==restore_zero|, then |save_index(p)| -is a location in |eqtb| whose current value should be destroyed at the end -of the current group, when it should be -replaced by the value of |eqtb[undefined_control_sequence]|. - -\yskip\hangg 3) If |save_type(p)==insert_token|, then |save_index(p)| -is a token that should be inserted into \TeX's input when the current -group ends. - -\yskip\hangg 4) If |save_type(p)==level_boundary|, then |save_level(p)| -is a code explaining what kind of group we were previously in, and -|save_index(p)| points to the level boundary word at the bottom of -the entries for that group. -Furthermore, in extended \eTeX\ mode, |save_stack[p-1]| contains the -source line number at which the current level of grouping was entered. - -\yskip\hang 5) If |save_type(p)==restore_sa|, then |sa_chain| points to a -chain of sparse array entries to be restored at the end of the current -group. Furthermore |save_index(p)| and |save_level(p)| should replace -the values of |sa_chain| and |sa_level| respectively. - -@d save_type(A) save_stack[A].hh.b0 /*classifies a |save_stack| entry*/ -@d save_level(A) save_stack[A].hh.b1 - /*saved level for regions 5 and 6, or group code*/ -@d save_index(A) save_stack[A].hh.rh - /*|eqtb| location or token or |save_stack| location*/ -@d restore_old_value 0 /*|save_type| when a value should be restored later*/ -@d restore_zero 1 /*|save_type| when an undefined entry should be restored*/ -@d insert_token 2 /*|save_type| when a token is being saved for later use*/ -@d level_boundary 3 /*|save_type| corresponding to beginning of group*/ -@d restore_sa 4 /*|save_type| when sparse array entries should be restored*/ - -@p @t\4@>@<Declare \eTeX\ procedures for tracing and input@>@; - -@ Here are the group codes that are used to discriminate between different -kinds of groups. They allow \TeX\ to decide what special actions, if any, -should be performed when a group ends. -\def\grp{\.{\char'173...\char'175}} - -Some groups are not supposed to be ended by right braces. For example, -the `\.\$' that begins a math formula causes a |math_shift_group| to -be started, and this should be terminated by a matching `\.\$'. Similarly, -a group that starts with \.{\\left} should end with \.{\\right}, and -one that starts with \.{\\begingroup} should end with \.{\\endgroup}. - -@d bottom_level 0 /*group code for the outside world*/ -@d simple_group 1 /*group code for local structure only*/ -@d hbox_group 2 /*code for `\.{\\hbox}\grp'*/ -@d adjusted_hbox_group 3 /*code for `\.{\\hbox}\grp' in vertical mode*/ -@d vbox_group 4 /*code for `\.{\\vbox}\grp'*/ -@d vtop_group 5 /*code for `\.{\\vtop}\grp'*/ -@d align_group 6 /*code for `\.{\\halign}\grp', `\.{\\valign}\grp'*/ -@d no_align_group 7 /*code for `\.{\\noalign}\grp'*/ -@d output_group 8 /*code for output routine*/ -@d math_group 9 /*code for, e.g., `\.{\char'136}\grp'*/ -@d disc_group 10 /*code for `\.{\\discretionary}\grp\grp\grp'*/ -@d insert_group 11 /*code for `\.{\\insert}\grp', `\.{\\vadjust}\grp'*/ -@d vcenter_group 12 /*code for `\.{\\vcenter}\grp'*/ -@d math_choice_group 13 /*code for `\.{\\mathchoice}\grp\grp\grp\grp'*/ -@d semi_simple_group 14 /*code for `\.{\\begingroup...\\endgroup}'*/ -@d math_shift_group 15 /*code for `\.{\$...\$}'*/ -@d math_left_group 16 /*code for `\.{\\left...\\right}'*/ -@d page_group 17 -@d stream_group 18 -@d stream_before_group 19 -@d stream_after_group 20 -@d outline_group 21 -@d max_group_code 21 - -@<Types...@>= -typedef int8_t group_code; /*|save_level| for a level boundary*/ - -@ The global variable |cur_group| keeps track of what sort of group we are -currently in. Another global variable, |cur_boundary|, points to the -topmost |level_boundary| word. And |cur_level| is the current depth of -nesting. The routines are designed to preserve the condition that no entry -in the |save_stack| or in |eqtb| ever has a level greater than |cur_level|. - -@ @<Glob...@>= -static memory_word @!save_stack[save_size+1]; -static memory_word @!save_hfactor[save_size+1]; -static memory_word @!save_vfactor[save_size+1]; -static int @!save_ptr; /*first unused entry on |save_stack|*/ -static int @!max_save_stack; /*maximum usage of save stack*/ -static quarterword @!cur_level; /*current nesting level for groups*/ -static group_code @!cur_group; /*current group type*/ -static int @!cur_boundary; /*where the current level begins*/ - -@ At this time it might be a good idea for the reader to review the introduction -to |eqtb| that was given above just before the long lists of parameter names. -Recall that the ``outer level'' of the program is |level_one|, since -undefined control sequences are assumed to be ``defined'' at |level_zero|. - -@<Set init...@>= -save_ptr=0;cur_level=level_one;cur_group=bottom_level;cur_boundary=0; -max_save_stack=0; - -@ The following macro is used to test if there is room for up to seven more -entries on |save_stack|. By making a conservative test like this, we can -get by with testing for overflow in only a few places. - -@d check_full_save_stack if (save_ptr > max_save_stack) - {@+max_save_stack=save_ptr; - if (max_save_stack > save_size-7) overflow("save size", save_size); -@:TeX capacity exceeded save size}{\quad save size@> - } - -@ Procedure |new_save_level| is called when a group begins. The -argument is a group identification code like `|hbox_group|'. After -calling this routine, it is safe to put five more entries on |save_stack|. - -In some cases integer-valued items are placed onto the -|save_stack| just below a |level_boundary| word, because this is a -convenient place to keep information that is supposed to ``pop up'' just -when the group has finished. -For example, when `\.{\\hbox to 100pt}\grp' is being treated, the 100pt -dimension is stored on |save_stack| just before |new_save_level| is -called. - -We use the notation |saved(k)| to stand for an integer item that -appears in location |save_ptr+k| of the save stack. - -@d saved(A) save_stack[save_ptr+A].i -@d saved_hfactor(A) save_hfactor[save_ptr+A].i -@d saved_vfactor(A) save_vfactor[save_ptr+A].i - -@p void new_save_level(group_code @!c) /*begin a new level of grouping*/ -{@+check_full_save_stack; -if (eTeX_ex) - {@+saved(0)=line;incr(save_ptr); - } -save_type(save_ptr)=level_boundary;save_level(save_ptr)=cur_group; -save_index(save_ptr)=cur_boundary; -if (cur_level==max_quarterword) overflow("grouping levels", -@:TeX capacity exceeded grouping levels}{\quad grouping levels@> - max_quarterword-min_quarterword); - /*quit if |(cur_level+1)| is too big to be stored in |eqtb|*/ -cur_boundary=save_ptr;cur_group=c; -#ifdef @!STAT -if (tracing_groups > 0) group_trace(false); -#endif -@;@/ -incr(cur_level);incr(save_ptr); -} - -@ Just before an entry of |eqtb| is changed, the following procedure should -be called to update the other data structures properly. It is important -to keep in mind that reference counts in |mem| include references from -within |save_stack|, so these counts must be handled carefully. -@^reference counts@> - -@p static void eq_destroy(memory_word @!w) /*gets ready to forget |w|*/ -{@+pointer q; /*|equiv| field of |w|*/ -switch (eq_type_field(w)) { -case call: case long_call: case outer_call: case long_outer_call: delete_token_ref(equiv_field(w));@+break; -case glue_ref: delete_glue_ref(equiv_field(w));@+break; -case shape_ref: {@+q=equiv_field(w); /*we need to free a \.{\\parshape} block*/ - if (q!=null) free_node(q, info(q)+info(q)+1); - } @+break; /*such a block is |2 n+1| words long, where |n==info(q)|*/ -case box_ref: flush_node_list(equiv_field(w));@+break; -@/@<Cases for |eq_destroy|@>@/ -default:do_nothing; -} -} - -@ To save a value of |eqtb[p]| that was established at level |l|, we -can use the following subroutine. - -@p static void eq_save(pointer @!p, quarterword @!l) /*saves |eqtb[p]|*/ -{@+check_full_save_stack; -if (l==level_zero) save_type(save_ptr)=restore_zero; -else{@+save_stack[save_ptr]=eqtb[p]; - if (p>=dimen_base) - { save_hfactor[save_ptr]=hfactor_eqtb[p]; - save_vfactor[save_ptr]=vfactor_eqtb[p]; - } - else if (p==par_shape_loc) - { save_hfactor[save_ptr].i=par_shape_hfactor; - save_vfactor[save_ptr].i=par_shape_vfactor; - } - incr(save_ptr); - save_type(save_ptr)=restore_old_value; - } -save_level(save_ptr)=l;save_index(save_ptr)=p;incr(save_ptr); -} - -@ The procedure |eq_define| defines an |eqtb| entry having specified -|eq_type| and |equiv| fields, and saves the former value if appropriate. -This procedure is used only for entries in the first four regions of |eqtb|, -i.e., only for entries that have |eq_type| and |equiv| fields. -After calling this routine, it is safe to put four more entries on -|save_stack|, provided that there was room for four more entries before -the call, since |eq_save| makes the necessary test. - -@p -#ifdef @!STAT -#define assign_trace(A, B) if (tracing_assigns > 0) restore_trace(A, B); -#else -#define assign_trace(A, B) -#endif - -static void eq_define(pointer @!p, quarterword @!t, halfword @!e) - /*new data for |eqtb|*/ -{@+ -if (eTeX_ex&&(eq_type(p)==t)&&(equiv(p)==e)) - {@+assign_trace(p,"reassigning")@;@/ - eq_destroy(eqtb[p]);return; - } -assign_trace(p,"changing")@;@/ -if (eq_level(p)==cur_level) eq_destroy(eqtb[p]); -else if (cur_level > level_one) eq_save(p, eq_level(p)); -eq_level(p)=cur_level;eq_type(p)=t;equiv(p)=e; -if (p==par_shape_loc) -{ par_shape_hfactor=cur_hfactor; - par_shape_vfactor=cur_vfactor; -} -assign_trace(p,"into")@;@/ -} - -@ The counterpart of |eq_define| for the remaining (fullword) positions in -|eqtb| is called |eq_word_define|. Since |xeq_level[p] >= level_one| for all -|p|, a `|restore_zero|' will never be used in this case. - -@p static void eq_word_define(pointer @!p, int @!w) -{@+ -if (eTeX_ex&&(eqtb[p].i==w)) - {@+assign_trace(p,"reassigning")@;@/ - return; - } -assign_trace(p,"changing")@;@/ -if (cur_level==level_one)@t\1@> - { if (p==dimen_base+hsize_code) - { hhsize=w+round(((double)cur_hfactor*hhsize +(double)cur_vfactor*hvsize)/unity); return; @+} - if (p==dimen_base+vsize_code) - { hvsize=w+round(((double)cur_hfactor*hhsize +(double)cur_vfactor*hvsize)/unity); return; @+} - } -if (xeq_level[p]!=cur_level) - {@+eq_save(p, xeq_level[p]);xeq_level[p]=cur_level; - } -eqtb[p].i=w; -if (p>=dimen_base) -{ hfactor_eqtb[p].i=cur_hfactor; - vfactor_eqtb[p].i=cur_vfactor; -} -assign_trace(p,"into")@;@/ -} - -@ The |eq_define| and |eq_word_define| routines take care of local definitions. -@^global definitions@> -Global definitions are done in almost the same way, but there is no need -to save old values, and the new value is associated with |level_one|. - -@p static void geq_define(pointer @!p, quarterword @!t, halfword @!e) - /*global |eq_define|*/ -{@+assign_trace(p,"globally changing")@;@/ -{@+eq_destroy(eqtb[p]); -eq_level(p)=level_one;eq_type(p)=t;equiv(p)=e; -} -assign_trace(p,"into");@/ -} -@# -static void geq_word_define(pointer @!p, int @!w) /*global |eq_word_define|*/ -{@+assign_trace(p,"globally changing")@;@/ -{@t\1@>xeq_level[p]=level_one; - if (p==dimen_base+hsize_code) - hhsize=w+round(((double)cur_hfactor*hhsize +(double)cur_vfactor*hvsize)/unity); - else if (p==dimen_base+vsize_code) - hvsize=w+round(((double)cur_hfactor*hhsize +(double)cur_vfactor*hvsize)/unity); - else - { eqtb[p].i=w; - if (p>=dimen_base) - { hfactor_eqtb[p].i=cur_hfactor; - vfactor_eqtb[p].i=cur_vfactor; - } -} -} -assign_trace(p,"into");@/ -} - -@ Subroutine |save_for_after| puts a token on the stack for save-keeping. - -@p static void save_for_after(halfword @!t) -{@+if (cur_level > level_one) - {@+check_full_save_stack; - save_type(save_ptr)=insert_token;save_level(save_ptr)=level_zero; - save_index(save_ptr)=t;incr(save_ptr); - } -} - -@ The |unsave| routine goes the other way, taking items off of |save_stack|. -This routine takes care of restoration when a level ends; everything -belonging to the topmost group is cleared off of the save stack. - -@p -static void back_input(void); -void unsave(void) /*pops the top level off the save stack*/ -{@+ -pointer p; /*position to be restored*/ -quarterword @!l; /*saved level, if in fullword regions of |eqtb|*/ -halfword @!t; /*saved value of |cur_tok|*/ -bool @!a; /*have we already processed an \.{\\aftergroup} ?*/ -a=false; -if (cur_level > level_one) - {@+decr(cur_level); - @<Clear off top level from |save_stack|@>; - } -else confusion("curlevel"); /*|unsave| is not used when |cur_group==bottom_level|*/ -@:this can't happen curlevel}{\quad curlevel@> -} - -@ @<Clear off...@>= -loop@+{@+decr(save_ptr); - if (save_type(save_ptr)==level_boundary) goto done; - p=save_index(save_ptr); - if (save_type(save_ptr)==insert_token) - @<Insert token |p| into \TeX's input@>@; - else if (save_type(save_ptr)==restore_sa) - {@+sa_restore();sa_chain=p;sa_level=save_level(save_ptr); - } - else{@+if (save_type(save_ptr)==restore_old_value) - {@+l=save_level(save_ptr);decr(save_ptr); - } - else save_stack[save_ptr]=eqtb[undefined_control_sequence]; - @<Store \(s)|save_stack[save_ptr]| in |eqtb[p]|, unless |eqtb[p]| holds a global -value@>; - } - } -done: -#ifdef @!STAT -if (tracing_groups > 0) group_trace(true); -#endif -@;@/ -if (grp_stack[in_open]==cur_boundary) group_warning(); - /*groups possibly not properly nested with files*/ -cur_group=save_level(save_ptr);cur_boundary=save_index(save_ptr); -if (eTeX_ex) decr(save_ptr) - -@ A global definition, which sets the level to |level_one|, -@^global definitions@> -will not be undone by |unsave|. If at least one global definition of -|eqtb[p]| has been carried out within the group that just ended, the -last such definition will therefore survive. - -@<Store \(s)|save...@>= -if (p < int_base) - if (eq_level(p)==level_one) - {@+eq_destroy(save_stack[save_ptr]); /*destroy the saved value*/ -#ifdef @!STAT - if (tracing_restores > 0) restore_trace(p,"retaining"); -#endif -@;@/ - } - else{@+eq_destroy(eqtb[p]); /*destroy the current value*/ - eqtb[p]=save_stack[save_ptr]; /*restore the saved value*/ - if (p==par_shape_loc) - { par_shape_hfactor=save_hfactor[save_ptr].i; - par_shape_vfactor=save_vfactor[save_ptr].i; - } -#ifdef @!STAT - if (tracing_restores > 0) restore_trace(p,"restoring"); -#endif -@;@/ - } -else if (xeq_level[p]!=level_one) - {@t\1@>@+eqtb[p]=save_stack[save_ptr]; - if (p>=dimen_base) - { hfactor_eqtb[p]=save_hfactor[save_ptr]; - vfactor_eqtb[p]=save_vfactor[save_ptr]; - } - xeq_level[p]=l; -#ifdef @!STAT - if (tracing_restores > 0) restore_trace(p,"restoring"); -#endif -@;@/ - } -else{ -#ifdef @!STAT - if (tracing_restores > 0) restore_trace(p,"retaining"); -#endif -@;@/ - } - -@ @<Declare \eTeX\ procedures for tr...@>= -#ifdef @!STAT -static void restore_trace(pointer @!p, char *@!s) - /*|eqtb[p]| has just been restored or retained*/ -{@+begin_diagnostic();print_char('{');print(s);print_char(' '); -show_eqtb(p);print_char('}'); -end_diagnostic(false); -} -#endif - -@ When looking for possible pointers to a memory location, it is helpful -to look for references from |eqtb| that might be waiting on the -save stack. Of course, we might find spurious pointers too; but this -routine is merely an aid when debugging, and at such times we are -grateful for any scraps of information, even if they prove to be irrelevant. -@^dirty \PASCAL@> - -@<Search |save_stack| for equivalents that point to |p|@>= -if (save_ptr > 0) for (q=0; q<=save_ptr-1; q++) - {@+if (equiv_field(save_stack[q])==p) - {@+print_nl("SAVE(");print_int(q);print_char(')'); - } - } - -@ Most of the parameters kept in |eqtb| can be changed freely, but there's -an exception: The magnification should not be used with two different -values during any \TeX\ job, since a single magnification is applied to an -entire run. The global variable |mag_set| is set to the current magnification -whenever it becomes necessary to ``freeze'' it at a particular value. - -@<Glob...@>= -static int @!mag_set; /*if nonzero, this magnification should be used henceforth*/ - -@ @<Set init...@>= -mag_set=0; - -@ The |prepare_mag| subroutine is called whenever \TeX\ wants to use |mag| -for magnification. - -@p static void prepare_mag(void) -{@+if ((mag_set > 0)&&(mag!=mag_set)) - {@+print_err("Incompatible magnification (");print_int(mag); -@.Incompatible magnification@> - print(");");print_nl(" the previous value will be retained"); - help2("I can handle only one magnification ratio per job. So I've",@/ - "reverted to the magnification you used earlier on this run.");@/ - int_error(mag_set); - geq_word_define(int_base+mag_code, mag_set); /*|mag=mag_set|*/ - } -if ((mag <= 0)||(mag > 32768)) - {@+print_err("Illegal magnification has been changed to 1000");@/ -@.Illegal magnification...@> - help1("The magnification ratio must be between 1 and 32768."); - int_error(mag);geq_word_define(int_base+mag_code, 1000); - } -mag_set=mag; -} - -@* Token lists. -A \TeX\ token is either a character or a control sequence, and it is -@^token@> -represented internally in one of two ways: (1)~A character whose ASCII -code number is |c| and whose command code is |m| is represented as the -number $2^8m+c$; the command code is in the range |1 <= m <= 14|. (2)~A control -sequence whose |eqtb| address is |p| is represented as the number -|cs_token_flag+p|. Here |cs_token_flag==@t$2^{12}-1$@>| is larger than -$2^8m+c$, yet it is small enough that |cs_token_flag+p < max_halfword|; -thus, a token fits comfortably in a halfword. - -A token |t| represents a |left_brace| command if and only if -|t < left_brace_limit|; it represents a |right_brace| command if and only if -we have |left_brace_limit <= t < right_brace_limit|; and it represents a |match| or -|end_match| command if and only if |match_token <= t <= end_match_token|. -The following definitions take care of these token-oriented constants -and a few others. - -@d cs_token_flag 07777 /*amount added to the |eqtb| location in a - token that stands for a control sequence; is a multiple of~256, less~1*/ -@d left_brace_token 00400 /*$2^8\cdot|left_brace|$*/ -@d left_brace_limit 01000 /*$2^8\cdot(|left_brace|+1)$*/ -@d right_brace_token 01000 /*$2^8\cdot|right_brace|$*/ -@d right_brace_limit 01400 /*$2^8\cdot(|right_brace|+1)$*/ -@d math_shift_token 01400 /*$2^8\cdot|math_shift|$*/ -@d tab_token 02000 /*$2^8\cdot|tab_mark|$*/ -@d out_param_token 02400 /*$2^8\cdot|out_param|$*/ -@d space_token 05040 /*$2^8\cdot|spacer|+|' '|$*/ -@d letter_token 05400 /*$2^8\cdot|letter|$*/ -@d other_token 06000 /*$2^8\cdot|other_char|$*/ -@d match_token 06400 /*$2^8\cdot|match|$*/ -@d end_match_token 07000 /*$2^8\cdot|end_match|$*/ -@d protected_token 07001 /*$2^8\cdot|end_match|+1$*/ - -@ @<Check the ``constant''...@>= -if (cs_token_flag+undefined_control_sequence > max_halfword) bad=21; - -@ A token list is a singly linked list of one-word nodes in |mem|, where -each word contains a token and a link. Macro definitions, output-routine -definitions, marks, \.{\\write} texts, and a few other things -are remembered by \TeX\ in the form -of token lists, usually preceded by a node with a reference count in its -|token_ref_count| field. The token stored in location |p| is called -|info(p)|. - -Three special commands appear in the token lists of macro definitions. -When |m==match|, it means that \TeX\ should scan a parameter -for the current macro; when |m==end_match|, it means that parameter -matching should end and \TeX\ should start reading the macro text; and -when |m==out_param|, it means that \TeX\ should insert parameter -number |c| into the text at this point. - -The enclosing \.{\char'173} and \.{\char'175} characters of a macro -definition are omitted, but an output routine -will be enclosed in braces. - -Here is an example macro definition that illustrates these conventions. -After \TeX\ processes the text -$$\.{\\def\\mac a\#1\#2 \\b \{\#1\\-a \#\#1\#2 \#2\}}$$ -the definition of \.{\\mac} is represented as a token list containing -$$\def\,{\hskip2pt} -\vbox{\halign{\hfil#\hfil\cr -(reference count), |letter|\,\.a, |match|\,\#, |match|\,\#, |spacer|\,\.\ , -\.{\\b}, |end_match|,\cr -|out_param|\,1, \.{\\-}, |letter|\,\.a, |spacer|\,\.\ , |mac_param|\,\#, -|other_char|\,\.1,\cr -|out_param|\,2, |spacer|\,\.\ , |out_param|\,2.\cr}}$$ -The procedure |scan_toks| builds such token lists, and |macro_call| -does the parameter matching. -@^reference counts@> - -Examples such as -$$\.{\\def\\m\{\\def\\m\{a\}\ b\}}$$ -explain why reference counts would be needed even if \TeX\ had no \.{\\let} -operation: When the token list for \.{\\m} is being read, the redefinition of -\.{\\m} changes the |eqtb| entry before the token list has been fully -consumed, so we dare not simply destroy a token list when its -control sequence is being redefined. - -If the parameter-matching part of a definition ends with `\.{\#\{}', -the corresponding token list will have `\.\{' just before the `|end_match|' -and also at the very end. The first `\.\{' is used to delimit the parameter; the -second one keeps the first from disappearing. - -@ The procedure |show_token_list|, which prints a symbolic form of -the token list that starts at a given node |p|, illustrates these -conventions. The token list being displayed should not begin with a reference -count. However, the procedure is intended to be robust, so that if the -memory links are awry or if |p| is not really a pointer to a token list, -nothing catastrophic will happen. - -An additional parameter |q| is also given; this parameter is either null -or it points to a node in the token list where a certain magic computation -takes place that will be explained later. (Basically, |q| is non-null when -we are printing the two-line context information at the time of an error -message; |q| marks the place corresponding to where the second line -should begin.) - -For example, if |p| points to the node containing the first \.a in the -token list above, then |show_token_list| will print the string -$$\hbox{`\.{a\#1\#2\ \\b\ ->\#1\\-a\ \#\#1\#2\ \#2}';}$$ -and if |q| points to the node containing the second \.a, -the magic computation will be performed just before the second \.a is printed. - -The generation will stop, and `\.{\\ETC.}' will be printed, if the length -of printing exceeds a given limit~|l|. Anomalous entries are printed in the -form of control sequences that are not followed by a blank space, e.g., -`\.{\\BAD.}'; this cannot be confused with actual control sequences because -a real control sequence named \.{BAD} would come out `\.{\\BAD\ }'. - -@<Declare the procedure called |show_token_list|@>= -static void show_token_list(int @!p, int @!q, int @!l) -{@+ -int m, @!c; /*pieces of a token*/ -ASCII_code @!match_chr; /*character used in a `|match|'*/ -ASCII_code @!n; /*the highest parameter number, as an ASCII digit*/ -match_chr='#';n='0';tally=0; -while ((p!=null)&&(tally < l)) - {@+if (p==q) @<Do magic computation@>; - @<Display token |p|, and |return| if there are problems@>; - p=link(p); - } -if (p!=null) print_esc("ETC."); -@.ETC@> - -} - -@ @<Display token |p|...@>= -if ((p < hi_mem_min)||(p > mem_end)) - {@+print_esc("CLOBBERED.");return; -@.CLOBBERED@> - } -if (info(p) >= cs_token_flag) print_cs(info(p)-cs_token_flag); -else{@+m=info(p)/0400;c=info(p)%0400; - if (info(p) < 0) print_esc("BAD."); -@.BAD@> - else@<Display the token $(|m|,|c|)$@>; - } - -@ The procedure usually ``learns'' the character code used for macro -parameters by seeing one in a |match| command before it runs into any -|out_param| commands. - -@<Display the token...@>= -switch (m) { -case left_brace: case right_brace: case math_shift: case tab_mark: case sup_mark: case sub_mark: case spacer: - case letter: case other_char: printn(c);@+break; -case mac_param: {@+printn(c);printn(c); - } @+break; -case out_param: {@+printn(match_chr); - if (c <= 9) print_char(c+'0'); - else{@+print_char('!');return; - } - } @+break; -case match: {@+match_chr=c;printn(c);incr(n);print_char(n); - if (n > '9') return; - } @+break; -case end_match: if (c==0) print("->");@+break; -@.->@> -default:print_esc("BAD."); -@.BAD@> -} - -@ Here's the way we sometimes want to display a token list, given a pointer -to its reference count; the pointer may be null. - -@p static void token_show(pointer @!p) -{@+if (p!=null) show_token_list(link(p), null, 10000000); -} - -@ The |print_meaning| subroutine displays |cur_cmd| and |cur_chr| in -symbolic form, including the expansion of a macro or mark. - -@p static void print_meaning(void) -{@+print_cmd_chr(cur_cmd, cur_chr); -if (cur_cmd >= call) - {@+print_char(':');print_ln();token_show(cur_chr); - } -else if (cur_cmd==top_bot_mark) - {@+print_char(':');print_ln(); - token_show(cur_mark[cur_chr]); - } -} - -@* Introduction to the syntactic routines. -Let's pause a moment now and try to look at the Big Picture. -The \TeX\ program consists of three main parts: syntactic routines, -semantic routines, and output routines. The chief purpose of the -syntactic routines is to deliver the user's input to the semantic routines, -one token at a time. The semantic routines act as an interpreter -responding to these tokens, which may be regarded as commands. And the -output routines are periodically called on to convert box-and-glue -lists into a compact set of instructions that will be sent -to a typesetter. We have discussed the basic data structures and utility -routines of \TeX, so we are good and ready to plunge into the real activity by -considering the syntactic routines. - -Our current goal is to come to grips with the |get_next| procedure, -which is the keystone of \TeX's input mechanism. Each call of |get_next| -sets the value of three variables |cur_cmd|, |cur_chr|, and |cur_cs|, -representing the next input token. -$$\vbox{\halign{#\hfil\cr - \hbox{|cur_cmd| denotes a command code from the long list of codes - given above;}\cr - \hbox{|cur_chr| denotes a character code or other modifier of the command - code;}\cr - \hbox{|cur_cs| is the |eqtb| location of the current control sequence,}\cr - \hbox{\qquad if the current token was a control sequence, - otherwise it's zero.}\cr}}$$ -Underlying this external behavior of |get_next| is all the machinery -necessary to convert from character files to tokens. At a given time we -may be only partially finished with the reading of several files (for -which \.{\\input} was specified), and partially finished with the expansion -of some user-defined macros and/or some macro parameters, and partially -finished with the generation of some text in a template for \.{\\halign}, -and so on. When reading a character file, special characters must be -classified as math delimiters, etc.; comments and extra blank spaces must -be removed, paragraphs must be recognized, and control sequences must be -found in the hash table. Furthermore there are occasions in which the -scanning routines have looked ahead for a word like `\.{plus}' but only -part of that word was found, hence a few characters must be put back -into the input and scanned again. - -To handle these situations, which might all be present simultaneously, -\TeX\ uses various stacks that hold information about the incomplete -activities, and there is a finite state control for each level of the -input mechanism. These stacks record the current state of an implicitly -recursive process, but the |get_next| procedure is not recursive. -Therefore it will not be difficult to translate these algorithms into -low-level languages that do not support recursion. - -@<Glob...@>= -static eight_bits @!cur_cmd; /*current command set by |get_next|*/ -static halfword @!cur_chr; /*operand of current command*/ -static pointer @!cur_cs; /*control sequence found here, zero if none found*/ -static halfword @!cur_tok; /*packed representative of |cur_cmd| and |cur_chr|*/ - -@ The |print_cmd_chr| routine prints a symbolic interpretation of a -command code and its modifier. This is used in certain `\.{You can\'t}' -error messages, and in the implementation of diagnostic routines like -\.{\\show}. - -The body of |print_cmd_chr| is a rather tedious listing of print -commands, and most of it is essentially an inverse to the |primitive| -routine that enters a \TeX\ primitive into |eqtb|. Therefore much of -this procedure appears elsewhere in the program, -together with the corresponding |primitive| calls. - -@d chr_cmd(A) {@+print(A);print_ASCII(chr_code); - } - -@<Declare the procedure called |print_cmd_chr|@>= -static void print_cmd_chr(quarterword @!cmd, halfword @!chr_code) -{@+int n; /*temp variable*/ -switch (cmd) { -case left_brace: chr_cmd("begin-group character ")@;@+break; -case right_brace: chr_cmd("end-group character ")@;@+break; -case math_shift: chr_cmd("math shift character ")@;@+break; -case mac_param: chr_cmd("macro parameter character ")@;@+break; -case sup_mark: chr_cmd("superscript character ")@;@+break; -case sub_mark: chr_cmd("subscript character ")@;@+break; -case endv: print("end of alignment template");@+break; -case spacer: chr_cmd("blank space ")@;@+break; -case letter: chr_cmd("the letter ")@;@+break; -case other_char: chr_cmd("the character ")@;@+break; -@t\4@>@<Cases of |print_cmd_chr| for symbolic printing of primitives@>@/ -default:print("[unknown command code!]"); -} -} - -@ Here is a procedure that displays the current command. - -@p static void show_cur_cmd_chr(void) -{@+int n; /*level of \.{\\if...\\fi} nesting*/ -int @!l; /*line where \.{\\if} started*/ -pointer @!p; -begin_diagnostic();print_nl("{"); -if (mode!=shown_mode) - {@+print_mode(mode);print(": ");shown_mode=mode; - } -print_cmd_chr(cur_cmd, cur_chr); -if (tracing_ifs > 0) - if (cur_cmd >= if_test) if (cur_cmd <= fi_or_else) - {@+print(": "); - if (cur_cmd==fi_or_else) - {@+print_cmd_chr(if_test, cur_if);print_char(' '); - n=0;l=if_line; - } - else{@+n=1;l=line; - } - p=cond_ptr; - while (p!=null) - {@+incr(n);p=link(p); - } - print("(level ");print_int(n);print_char(')');print_if_line(l); - } -print_char('}'); -end_diagnostic(false); -} - -@* Input stacks and states. -This implementation of -\TeX\ uses two different conventions for representing sequential stacks. -@^stack conventions@>@^conventions for representing stacks@> - -\yskip\hangg 1) If there is frequent access to the top entry, and if the -stack is essentially never empty, then the top entry is kept in a global -variable (even better would be a machine register), and the other entries -appear in the array $\\{stack}[0\to(\\{ptr}-1)]$. For example, the -semantic stack described above is handled this way, and so is the input -stack that we are about to study. - -\yskip\hangg 2) If there is infrequent top access, the entire stack contents -are in the array $\\{stack}[0\to(\\{ptr}-1)]$. For example, the |save_stack| -is treated this way, as we have seen. - -\yskip\noindent -The state of \TeX's input mechanism appears in the input stack, whose -entries are records with six fields, called |state|, |index|, |start|, |loc|, -|limit|, and |name|. This stack is maintained with -convention~(1), so it is declared in the following way: - -@<Types...@>= -typedef struct { - quarterword @!state_field, @!index_field; - halfword @!start_field, @!loc_field, @!limit_field, @!name_field; - } in_state_record; - -@ @<Glob...@>= -static in_state_record @!input_stack[stack_size+1]; -static int @!input_ptr; /*first unused location of |input_stack|*/ -static int @!max_in_stack; /*largest value of |input_ptr| when pushing*/ -static in_state_record @!cur_input; - /*the ``top'' input state, according to convention (1)*/ - -@ We've already defined the special variable |loc====cur_input.loc_field| -in our discussion of basic input-output routines. The other components of -|cur_input| are defined in the same way: - -@d state cur_input.state_field /*current scanner state*/ -@d index cur_input.index_field /*reference for buffer information*/ -@d start cur_input.start_field /*starting position in |buffer|*/ -@d limit cur_input.limit_field /*end of current line in |buffer|*/ -@d name cur_input.name_field /*name of the current file*/ - -@ Let's look more closely now at the control variables -(|state|,~|index|,~|start|,~|loc|,~|limit|,~|name|), -assuming that \TeX\ is reading a line of characters that have been input -from some file or from the user's terminal. There is an array called -|buffer| that acts as a stack of all lines of characters that are -currently being read from files, including all lines on subsidiary -levels of the input stack that are not yet completed. \TeX\ will return to -the other lines when it is finished with the present input file. - -(Incidentally, on a machine with byte-oriented addressing, it might be -appropriate to combine |buffer| with the |str_pool| array, -letting the buffer entries grow downward from the top of the string pool -and checking that these two tables don't bump into each other.) - -The line we are currently working on begins in position |start| of the -buffer; the next character we are about to read is |buffer[loc]|; and -|limit| is the location of the last character present. If |loc > limit|, -the line has been completely read. Usually |buffer[limit]| is the -|end_line_char|, denoting the end of a line, but this is not -true if the current line is an insertion that was entered on the user's -terminal in response to an error message. - -The |name| variable is a string number that designates the name of -the current file, if we are reading a text file. It is zero if we -are reading from the terminal; it is |n+1| if we are reading from -input stream |n|, where |0 <= n <= 16|. (Input stream 16 stands for -an invalid stream number; in such cases the input is actually from -the terminal, under control of the procedure |read_toks|.) -Finally |18 <= name <= 19| indicates that we are reading a pseudo file -created by the \.{\\scantokens} command. - -The |state| variable has one of three values, when we are scanning such -files: -$$\baselineskip 15pt\vbox{\halign{#\hfil\cr -1) |state==mid_line| is the normal state.\cr -2) |state==skip_blanks| is like |mid_line|, but blanks are ignored.\cr -3) |state==new_line| is the state at the beginning of a line.\cr}}$$ -These state values are assigned numeric codes so that if we add the state -code to the next character's command code, we get distinct values. For -example, `|mid_line+spacer|' stands for the case that a blank -space character occurs in the middle of a line when it is not being -ignored; after this case is processed, the next value of |state| will -be |skip_blanks|. - -@d mid_line 1 /*|state| code when scanning a line of characters*/ -@d skip_blanks (2+max_char_code) /*|state| code when ignoring blanks*/ -@d new_line (3+max_char_code+max_char_code) /*|state| code at start of line*/ - -@ Additional information about the current line is available via the -|index| variable, which counts how many lines of characters are present -in the buffer below the current level. We have |index==0| when reading -from the terminal and prompting the user for each line; then if the user types, -e.g., `\.{\\input paper}', we will have |index==1| while reading -the file \.{paper.tex}. However, it does not follow that |index| is the -same as the input stack pointer, since many of the levels on the input -stack may come from token lists. For example, the instruction `\.{\\input -paper}' might occur in a token list. - -The global variable |in_open| is equal to the |index| -value of the highest non-token-list level. Thus, the number of partially read -lines in the buffer is |in_open+1|, and we have |in_open==index| -when we are not reading a token list. - -If we are not currently reading from the terminal, or from an input -stream, we are reading from the file variable |input_file[index]|. We use -the notation |terminal_input| as a convenient abbreviation for |name==0|, -and |cur_file| as an abbreviation for |input_file[index]|. - -The global variable |line| contains the line number in the topmost -open file, for use in error messages. If we are not reading from -the terminal, |line_stack[index]| holds the line number for the -enclosing level, so that |line| can be restored when the current -file has been read. Line numbers should never be negative, since the -negative of the current line number is used to identify the user's output -routine in the |mode_line| field of the semantic nest entries. - -If more information about the input state is needed, it can be -included in small arrays like those shown here. For example, -the current page or segment number in the input file might be -put into a variable |@!page|, maintained for enclosing levels in -`\ignorespaces|@!page_stack: array[1 dotdot max_in_open]int|\unskip' -by analogy with |line_stack|. -@^system dependencies@> - -@d terminal_input (name==0) /*are we reading from the terminal?*/ -@d cur_file input_file[index] /*the current |alpha_file| variable*/ - -@<Glob...@>= -static int @!in_open; /*the number of lines in the buffer, less one*/ -static int @!open_parens; /*the number of open text files*/ -static alpha_file @!input_file0[max_in_open], *const @!input_file = @!input_file0-1; -int @!line; /*current line number in the current source file*/ -static int @!line_stack0[max_in_open], *const @!line_stack = @!line_stack0-1; - -@ Users of \TeX\ sometimes forget to balance left and right braces properly, -and one of the ways \TeX\ tries to spot such errors is by considering an -input file as broken into subfiles by control sequences that -are declared to be \.{\\outer}. - -A variable called |scanner_status| tells \TeX\ whether or not to complain -when a subfile ends. This variable has six possible values: - -\yskip\hang|normal|, means that a subfile can safely end here without incident. - -\yskip\hang|skipping|, means that a subfile can safely end here, but not a file, -because we're reading past some conditional text that was not selected. - -\yskip\hang|defining|, means that a subfile shouldn't end now because a -macro is being defined. - -\yskip\hang|matching|, means that a subfile shouldn't end now because a -macro is being used and we are searching for the end of its arguments. - -\yskip\hang|aligning|, means that a subfile shouldn't end now because we are -not finished with the preamble of an \.{\\halign} or \.{\\valign}. - -\yskip\hang|absorbing|, means that a subfile shouldn't end now because we are -reading a balanced token list for \.{\\message}, \.{\\write}, etc. - -\yskip\noindent -If the |scanner_status| is not |normal|, the variable |warning_index| points -to the |eqtb| location for the relevant control sequence name to print -in an error message. - -@d skipping 1 /*|scanner_status| when passing conditional text*/ -@d defining 2 /*|scanner_status| when reading a macro definition*/ -@d matching 3 /*|scanner_status| when reading macro arguments*/ -@d aligning 4 /*|scanner_status| when reading an alignment preamble*/ -@d absorbing 5 /*|scanner_status| when reading a balanced text*/ - -@<Glob...@>= -static int @!scanner_status; /*can a subfile end now?*/ -static pointer @!warning_index; /*identifier relevant to non-|normal| scanner status*/ -static pointer @!def_ref; /*reference count of token list being defined*/ - -@ Here is a procedure that uses |scanner_status| to print a warning message -when a subfile has ended, and at certain other crucial times: - -@<Declare the procedure called |runaway|@>= -static void runaway(void) -{@+pointer p; /*head of runaway list*/ -if (scanner_status > skipping) - {@+print_nl("Runaway "); -@.Runaway...@> - switch (scanner_status) { - case defining: {@+print("definition");p=def_ref; - } @+break; - case matching: {@+print("argument");p=temp_head; - } @+break; - case aligning: {@+print("preamble");p=hold_head; - } @+break; - case absorbing: {@+print("text");p=def_ref; - } - } /*there are no other cases*/ - print_char('?');print_ln();show_token_list(link(p), null, error_line-10); - } -} - -@ However, all this discussion about input state really applies only to the -case that we are inputting from a file. There is another important case, -namely when we are currently getting input from a token list. In this case -|state==token_list|, and the conventions about the other state variables -are different: - -\yskip\hang|loc| is a pointer to the current node in the token list, i.e., -the node that will be read next. If |loc==null|, the token list has been -fully read. - -\yskip\hang|start| points to the first node of the token list; this node -may or may not contain a reference count, depending on the type of token -list involved. - -\yskip\hang|token_type|, which takes the place of |index| in the -discussion above, is a code number that explains what kind of token list -is being scanned. - -\yskip\hang|name| points to the |eqtb| address of the control sequence -being expanded, if the current token list is a macro. - -\yskip\hang|param_start|, which takes the place of |limit|, tells where -the parameters of the current macro begin in the |param_stack|, if the -current token list is a macro. - -\yskip\noindent The |token_type| can take several values, depending on -where the current token list came from: - -\yskip\hang|parameter|, if a parameter is being scanned; - -\hang|u_template|, if the \<u_j> part of an alignment -template is being scanned; - -\hang|v_template|, if the \<v_j> part of an alignment -template is being scanned; - -\hang|backed_up|, if the token list being scanned has been inserted as -`to be read again'; - -\hang|inserted|, if the token list being scanned has been inserted as -the text expansion of a \.{\\count} or similar variable; - -\hang|macro|, if a user-defined control sequence is being scanned; - -\hang|output_text|, if an \.{\\output} routine is being scanned; - -\hang|every_par_text|, if the text of \.{\\everypar} is being scanned; - -\hang|every_math_text|, if the text of \.{\\everymath} is being scanned; - -\hang|every_display_text|, if the text of \.{\\everydisplay} is being scanned; - -\hang|every_hbox_text|, if the text of \.{\\everyhbox} is being scanned; - -\hang|every_vbox_text|, if the text of \.{\\everyvbox} is being scanned; - -\hang|every_job_text|, if the text of \.{\\everyjob} is being scanned; - -\hang|every_cr_text|, if the text of \.{\\everycr} is being scanned; - -\hang|mark_text|, if the text of a \.{\\mark} is being scanned; - -\hang|write_text|, if the text of a \.{\\write} is being scanned. - -\yskip\noindent -The codes for |output_text|, |every_par_text|, etc., are equal to a constant -plus the corresponding codes for token list parameters |output_routine_loc|, -|every_par_loc|, etc. The token list begins with a reference count if and -only if |token_type >= macro|. -@^reference counts@> - -Since \eTeX's additional token list parameters precede |toks_base|, the -corresponding token types must precede |write_text|. - -@d token_list 0 /*|state| code when scanning a token list*/ -@d token_type index /*type of current token list*/ -@d param_start limit /*base of macro parameters in |param_stack|*/ -@d parameter 0 /*|token_type| code for parameter*/ -@d u_template 1 /*|token_type| code for \<u_j> template*/ -@d v_template 2 /*|token_type| code for \<v_j> template*/ -@d backed_up 3 /*|token_type| code for text to be reread*/ -@d inserted 4 /*|token_type| code for inserted texts*/ -@d macro 5 /*|token_type| code for defined control sequences*/ -@d output_text 6 /*|token_type| code for output routines*/ -@d every_par_text 7 /*|token_type| code for \.{\\everypar}*/ -@d every_math_text 8 /*|token_type| code for \.{\\everymath}*/ -@d every_display_text 9 /*|token_type| code for \.{\\everydisplay}*/ -@d every_hbox_text 10 /*|token_type| code for \.{\\everyhbox}*/ -@d every_vbox_text 11 /*|token_type| code for \.{\\everyvbox}*/ -@d every_job_text 12 /*|token_type| code for \.{\\everyjob}*/ -@d every_cr_text 13 /*|token_type| code for \.{\\everycr}*/ -@d mark_text 14 /*|token_type| code for \.{\\topmark}, etc.*/ -@# -@d eTeX_text_offset (output_routine_loc-output_text) -@d every_eof_text (every_eof_loc-eTeX_text_offset) - /*|token_type| code for \.{\\everyeof}*/ -@# -@d write_text (toks_base-eTeX_text_offset) /*|token_type| code for \.{\\write}*/ - -@ The |param_stack| is an auxiliary array used to hold pointers to the token -lists for parameters at the current level and subsidiary levels of input. -This stack is maintained with convention (2), and it grows at a different -rate from the others. - -@<Glob...@>= -static pointer @!param_stack[param_size+1]; - /*token list pointers for parameters*/ -static int @!param_ptr; /*first unused entry in |param_stack|*/ -static int @!max_param_stack; - /*largest value of |param_ptr|, will be | <= param_size+9|*/ - -@ The input routines must also interact with the processing of -\.{\\halign} and \.{\\valign}, since the appearance of tab marks and -\.{\\cr} in certain places is supposed to trigger the beginning of special -\<v_j> template text in the scanner. This magic is accomplished by an -|align_state| variable that is increased by~1 when a `\.{\char'173}' is -scanned and decreased by~1 when a `\.{\char'175}' is scanned. The |align_state| -is nonzero during the \<u_j> template, after which it is set to zero; the -\<v_j> template begins when a tab mark or \.{\\cr} occurs at a time that -|align_state==0|. - -@<Glob...@>= -static int @!align_state; /*group level with respect to current alignment*/ - -@ Thus, the ``current input state'' can be very complicated indeed; there -can be many levels and each level can arise in a variety of ways. The -|show_context| procedure, which is used by \TeX's error-reporting routine to -print out the current input state on all levels down to the most recent -line of characters from an input file, illustrates most of these conventions. -The global variable |base_ptr| contains the lowest level that was -displayed by this procedure. - -@<Glob...@>= -static int @!base_ptr; /*shallowest level shown by |show_context|*/ - -@ The status at each level is indicated by printing two lines, where the first -line indicates what was read so far and the second line shows what remains -to be read. The context is cropped, if necessary, so that the first line -contains at most |half_error_line| characters, and the second contains -at most |error_line|. Non-current input levels whose |token_type| is -`|backed_up|' are shown only if they have not been fully read. - -@p static void show_context(void) /*prints where the scanner is*/ -{@+ -int old_setting; /*saved |selector| setting*/ -int @!nn; /*number of contexts shown so far, less one*/ -bool @!bottom_line; /*have we reached the final context to be shown?*/ -@<Local variables for formatting calculations@>@/ -base_ptr=input_ptr;input_stack[base_ptr]=cur_input; - /*store current state*/ -nn=-1;bottom_line=false; -loop@+{@+cur_input=input_stack[base_ptr]; /*enter into the context*/ - if ((state!=token_list)) - if ((name > 19)||(base_ptr==0)) bottom_line=true; - if ((base_ptr==input_ptr)||bottom_line||(nn < error_context_lines)) - @<Display the current context@>@; - else if (nn==error_context_lines) - {@+print_nl("...");incr(nn); /*omitted if |error_context_lines < 0|*/ - } - if (bottom_line) goto done; - decr(base_ptr); - } -done: cur_input=input_stack[input_ptr]; /*restore original state*/ -} - -@ @<Display the current context@>= -{@+if ((base_ptr==input_ptr)||(state!=token_list)|| - (token_type!=backed_up)||(loc!=null)) - /*we omit backed-up token lists that have already been read*/ - {@+tally=0; /*get ready to count characters*/ - old_setting=selector; - if (state!=token_list) - {@+@<Print location of current line@>; - @<Pseudoprint the line@>; - } - else{@+@<Print type of token list@>; - @<Pseudoprint the token list@>; - } - selector=old_setting; /*stop pseudoprinting*/ - @<Print two lines using the tricky pseudoprinted information@>; - incr(nn); - } -} - -@ This routine should be changed, if necessary, to give the best possible -indication of where the current line resides in the input file. -For example, on some systems it is best to print both a page and line number. -@^system dependencies@> - -@<Print location of current line@>= -if (name <= 17) - if (terminal_input) - if (base_ptr==0) print_nl("<*>");else print_nl("<insert> "); - else{@+print_nl("<read "); - if (name==17) print_char('*');@+else print_int(name-1); -@.*\relax@> - print_char('>'); - } -else{@+print_nl("l."); - if (index==in_open) print_int(line); - else print_int(line_stack[index+1]); /*input from a pseudo file*/ - } -print_char(' ') - -@ @<Print type of token list@>= -switch (token_type) { -case parameter: print_nl("<argument> ");@+break; -case u_template: case v_template: print_nl("<template> ");@+break; -case backed_up: if (loc==null) print_nl("<recently read> "); - else print_nl("<to be read again> ");@+break; -case inserted: print_nl("<inserted text> ");@+break; -case macro: {@+print_ln();print_cs(name); - } @+break; -case output_text: print_nl("<output> ");@+break; -case every_par_text: print_nl("<everypar> ");@+break; -case every_math_text: print_nl("<everymath> ");@+break; -case every_display_text: print_nl("<everydisplay> ");@+break; -case every_hbox_text: print_nl("<everyhbox> ");@+break; -case every_vbox_text: print_nl("<everyvbox> ");@+break; -case every_job_text: print_nl("<everyjob> ");@+break; -case every_cr_text: print_nl("<everycr> ");@+break; -case mark_text: print_nl("<mark> ");@+break; -case every_eof_text: print_nl("<everyeof> ");@+break; -case write_text: print_nl("<write> ");@+break; -default:print_nl("?"); /*this should never happen*/ -} - -@ Here it is necessary to explain a little trick. We don't want to store a long -string that corresponds to a token list, because that string might take up -lots of memory; and we are printing during a time when an error message is -being given, so we dare not do anything that might overflow one of \TeX's -tables. So `pseudoprinting' is the answer: We enter a mode of printing -that stores characters into a buffer of length |error_line|, where character -$k+1$ is placed into \hbox{|trick_buf[k%error_line]|} if -|k < trick_count|, otherwise character |k| is dropped. Initially we set -|tally=0| and |trick_count=1000000|; then when we reach the -point where transition from line 1 to line 2 should occur, we -set |first_count=tally| and |trick_count=@tmax@>(error_line, -tally+1+error_line-half_error_line)|. At the end of the -pseudoprinting, the values of |first_count|, |tally|, and -|trick_count| give us all the information we need to print the two lines, -and all of the necessary text is in |trick_buf|. - -Namely, let |l| be the length of the descriptive information that appears -on the first line. The length of the context information gathered for that -line is |k==first_count|, and the length of the context information -gathered for line~2 is $m=\min(|tally|, |trick_count|)-k$. If |l+k <= h|, -where |h==half_error_line|, we print |trick_buf[0 dotdot k-1]| after the -descriptive information on line~1, and set |n=l+k|; here |n| is the -length of line~1. If $l+k>h$, some cropping is necessary, so we set |n=h| -and print `\.{...}' followed by -$$\hbox{|trick_buf[(l+k-h+3)dotdot k-1]|,}$$ -where subscripts of |trick_buf| are circular modulo |error_line|. The -second line consists of |n|~spaces followed by |trick_buf[k dotdot(k+m-1)]|, -unless |n+m > error_line|; in the latter case, further cropping is done. -This is easier to program than to explain. - -@<Local variables for formatting...@>= -int @!i; /*index into |buffer|*/ -int @!j; /*end of current line in |buffer|*/ -int @!l; /*length of descriptive information on line 1*/ -int @!m; /*context information gathered for line 2*/ -int @!n; /*length of line 1*/ -int @!p; /*starting or ending place in |trick_buf|*/ -int @!q; /*temporary index*/ - -@ The following code sets up the print routines so that they will gather -the desired information. - -@d begin_pseudoprint - {@+l=tally;tally=0;selector=pseudo; - trick_count=1000000; - } -@d set_trick_count - {@+first_count=tally; - trick_count=tally+1+error_line-half_error_line; - if (trick_count < error_line) trick_count=error_line; - } - -@ And the following code uses the information after it has been gathered. - -@<Print two lines using the tricky pseudoprinted information@>= -if (trick_count==1000000) set_trick_count; - /*|set_trick_count| must be performed*/ -if (tally < trick_count) m=tally-first_count; -else m=trick_count-first_count; /*context on line 2*/ -if (l+first_count <= half_error_line) - {@+p=0;n=l+first_count; - } -else{@+print("...");p=l+first_count-half_error_line+3; - n=half_error_line; - } -for (q=p; q<=first_count-1; q++) print_char(trick_buf[q%error_line]); -print_ln(); -for (q=1; q<=n; q++) print_char(' '); /*print |n| spaces to begin line~2*/ -if (m+n <= error_line) p=first_count+m;else p=first_count+(error_line-n-3); -for (q=first_count; q<=p-1; q++) print_char(trick_buf[q%error_line]); -if (m+n > error_line) print("...") - -@ But the trick is distracting us from our current goal, which is to -understand the input state. So let's concentrate on the data structures that -are being pseudoprinted as we finish up the |show_context| procedure. - -@<Pseudoprint the line@>= -begin_pseudoprint; -if (buffer[limit]==end_line_char) j=limit; -else j=limit+1; /*determine the effective end of the line*/ -if (j > 0) for (i=start; i<=j-1; i++) - {@+if (i==loc) set_trick_count; - printn(buffer[i]); - } - -@ @<Pseudoprint the token list@>= -begin_pseudoprint; -if (token_type < macro) show_token_list(start, loc, 100000); -else show_token_list(link(start), loc, 100000) /*avoid reference count*/ - -@ Here is the missing piece of |show_token_list| that is activated when the -token beginning line~2 is about to be shown: - -@<Do magic computation@>=set_trick_count - -@* Maintaining the input stacks. -The following subroutines change the input status in commonly needed ways. - -First comes |push_input|, which stores the current state and creates a -new level (having, initially, the same properties as the old). - -@d push_input @t@> /*enter a new input level, save the old*/ - {@+if (input_ptr > max_in_stack) - {@+max_in_stack=input_ptr; - if (input_ptr==stack_size) overflow("input stack size", stack_size); -@:TeX capacity exceeded input stack size}{\quad input stack size@> - } - input_stack[input_ptr]=cur_input; /*stack the record*/ - incr(input_ptr); - } - -@ And of course what goes up must come down. - -@d pop_input @t@> /*leave an input level, re-enter the old*/ - {@+decr(input_ptr);cur_input=input_stack[input_ptr]; - } - -@ Here is a procedure that starts a new level of token-list input, given -a token list |p| and its type |t|. If |t==macro|, the calling routine should -set |name| and |loc|. - -@d back_list(A) begin_token_list(A, backed_up) /*backs up a simple token list*/ -@d ins_list(A) begin_token_list(A, inserted) /*inserts a simple token list*/ - -@p void begin_token_list(pointer @!p, quarterword @!t) -{@+push_input;state=token_list;start=p;token_type=t; -if (t >= macro) /*the token list starts with a reference count*/ - {@+add_token_ref(p); - if (t==macro) param_start=param_ptr; - else{@+loc=link(p); - if (tracing_macros > 1) - {@+begin_diagnostic();print_nl(""); - switch (t) { - case mark_text: print_esc("mark");@+break; - case write_text: print_esc("write");@+break; - default:print_cmd_chr(assign_toks, t-output_text+output_routine_loc); - } @/ - print("->");token_show(p);end_diagnostic(false); - } - } - } -else loc=p; -} - -@ When a token list has been fully scanned, the following computations -should be done as we leave that level of input. The |token_type| tends -to be equal to either |backed_up| or |inserted| about 2/3 of the time. -@^inner loop@> - -@p static void end_token_list(void) /*leave a token-list input level*/ -{@+if (token_type >= backed_up) /*token list to be deleted*/ - {@+if (token_type <= inserted) flush_list(start); - else{@+delete_token_ref(start); /*update reference count*/ - if (token_type==macro) /*parameters must be flushed*/ - while (param_ptr > param_start) - {@+decr(param_ptr); - flush_list(param_stack[param_ptr]); - } - } - } -else if (token_type==u_template) - if (align_state > 500000) align_state=0; - else fatal_error("(interwoven alignment preambles are not allowed)"); -@.interwoven alignment preambles...@> -pop_input; -check_interrupt; -} - -@ Sometimes \TeX\ has read too far and wants to ``unscan'' what it has -seen. The |back_input| procedure takes care of this by putting the token -just scanned back into the input stream, ready to be read again. This -procedure can be used only if |cur_tok| represents the token to be -replaced. Some applications of \TeX\ use this procedure a lot, -so it has been slightly optimized for speed. -@^inner loop@> - -@p static void back_input(void) /*undoes one token of input*/ -{@+pointer p; /*a token list of length one*/ -while ((state==token_list)&&(loc==null)&&(token_type!=v_template)) - end_token_list(); /*conserve stack space*/ -p=get_avail();info(p)=cur_tok; -if (cur_tok < right_brace_limit) - if (cur_tok < left_brace_limit) decr(align_state); - else incr(align_state); -push_input;state=token_list;start=p;token_type=backed_up; -loc=p; /*that was |back_list(p)|, without procedure overhead*/ -} - -@ @<Insert token |p| into \TeX's input@>= -{@+t=cur_tok;cur_tok=p; -if (a) - {@+p=get_avail();info(p)=cur_tok;link(p)=loc;loc=p;start=p; - if (cur_tok < right_brace_limit) - if (cur_tok < left_brace_limit) decr(align_state); - else incr(align_state); - } -else{@+back_input();a=eTeX_ex; - } -cur_tok=t; -} - -@ The |back_error| routine is used when we want to replace an offending token -just before issuing an error message. This routine, like |back_input|, -requires that |cur_tok| has been set. We disable interrupts during the -call of |back_input| so that the help message won't be lost. - -@p static void back_error(void) /*back up one token and call |error|*/ -{@+OK_to_interrupt=false;back_input();OK_to_interrupt=true;error(); -} -@# -static void ins_error(void) /*back up one inserted token and call |error|*/ -{@+OK_to_interrupt=false;back_input();token_type=inserted; -OK_to_interrupt=true;error(); -} - -@ The |begin_file_reading| procedure starts a new level of input for lines -of characters to be read from a file, or as an insertion from the -terminal. It does not take care of opening the file, nor does it set |loc| -or |limit| or |line|. -@^system dependencies@> - -@p static void begin_file_reading(void) -{@+if (in_open==max_in_open) overflow("text input levels", max_in_open); -@:TeX capacity exceeded text input levels}{\quad text input levels@> -if (first==buf_size) overflow("buffer size", buf_size); -@:TeX capacity exceeded buffer size}{\quad buffer size@> -incr(in_open);push_input;index=in_open;@/ -source_filename_stack[index]=0; /* k\TeX\ */ -eof_seen[index]=false; -grp_stack[index]=cur_boundary;if_stack[index]=cond_ptr; -line_stack[index]=line;start=first;state=mid_line; -name=0; /*|terminal_input| is now |true|*/ -} - -@ Conversely, the variables must be downdated when such a level of input -is finished: - -@p static void end_file_reading(void) -{@+first=start;line=line_stack[index]; -if ((name==18)||(name==19)) pseudo_close();else -if (name > 17) a_close(&cur_file); /*forget it*/ -pop_input;decr(in_open); -} - -@ In order to keep the stack from overflowing during a long sequence of -inserted `\.{\\show}' commands, the following routine removes completed -error-inserted lines from memory. - -@p static void clear_for_error_prompt(void) -{@+while ((state!=token_list)&&terminal_input&&@| - (input_ptr > 0)&&(loc > limit)) end_file_reading(); -print_ln();clear_terminal; -} - -@ To get \TeX's whole input mechanism going, we perform the following -actions. - -@<Initialize the input routines@>= -{@+input_ptr=0;max_in_stack=0; -in_open=0;open_parens=0;max_buf_stack=0; -grp_stack[0]=0;if_stack[0]=null; -param_ptr=0;max_param_stack=0; -first=buf_size;@/do@+{buffer[first]=0;decr(first);}@+ while (!(first==0)); -scanner_status=normal;warning_index=null;first=1; -state=new_line;start=1;index=0;line=0;name=0; -force_eof=false; -align_state=1000000;@/ -if (!init_terminal()) exit(0); -limit=last;first=last+1; /*|init_terminal| has set |loc| and |last|*/ -} - -@* Getting the next token. -The heart of \TeX's input mechanism is the |get_next| procedure, which -we shall develop in the next few sections of the program. Perhaps we -shouldn't actually call it the ``heart,'' however, because it really acts -as \TeX's eyes and mouth, reading the source files and gobbling them up. -And it also helps \TeX\ to regurgitate stored token lists that are to be -processed again. -@^eyes and mouth@> - -The main duty of |get_next| is to input one token and to set |cur_cmd| -and |cur_chr| to that token's command code and modifier. Furthermore, if -the input token is a control sequence, the |eqtb| location of that control -sequence is stored in |cur_cs|; otherwise |cur_cs| is set to zero. - -Underlying this simple description is a certain amount of complexity -because of all the cases that need to be handled. -However, the inner loop of |get_next| is reasonably short and fast. - -When |get_next| is asked to get the next token of a \.{\\read} line, -it sets |cur_cmd==cur_chr==cur_cs==0| in the case that no more tokens -appear on that line. (There might not be any tokens at all, if the -|end_line_char| has |ignore| as its catcode.) - -@ The value of |par_loc| is the |eqtb| address of `\.{\\par}'. This quantity -is needed because a blank line of input is supposed to be exactly equivalent -to the appearance of \.{\\par}; we must set |cur_cs=par_loc| -when detecting a blank line. - -@<Glob...@>= -static pointer @!par_loc; /*location of `\.{\\par}' in |eqtb|*/ -static halfword @!par_token; /*token representing `\.{\\par}'*/ - -@ @<Put each...@>= -primitive("par", par_end, 256); /*cf.\ |scan_file_name|*/ -@!@:par\_}{\.{\\par} primitive@> -par_loc=cur_val;par_token=cs_token_flag+par_loc; - -@ @<Cases of |print_cmd_chr|...@>= -case par_end: print_esc("par");@+break; - -@ Before getting into |get_next|, let's consider the subroutine that -is called when an `\.{\\outer}' control sequence has been scanned or -when the end of a file has been reached. These two cases are distinguished -by |cur_cs|, which is zero at the end of a file. - -@p static void check_outer_validity(void) -{@+pointer p; /*points to inserted token list*/ -pointer @!q; /*auxiliary pointer*/ -if (scanner_status!=normal) - {@+deletions_allowed=false; - @<Back up an outer control sequence so that it can be reread@>; - if (scanner_status > skipping) - @<Tell the user what has run away and try to recover@>@; - else{@+print_err("Incomplete ");print_cmd_chr(if_test, cur_if); -@.Incomplete \\if...@> - print("; all text was ignored after line ");print_int(skip_line); - help3("A forbidden control sequence occurred in skipped text.",@/ - "This kind of error happens when you say `\\if...' and forget",@/ - "the matching `\\fi'. I've inserted a `\\fi'; this might work."); - if (cur_cs!=0) cur_cs=0; - else help_line[2]=@| - "The file ended while I was skipping conditional text."; - cur_tok=cs_token_flag+frozen_fi;ins_error(); - } - deletions_allowed=true; - } -} - -@ An outer control sequence that occurs in a \.{\\read} will not be reread, -since the error recovery for \.{\\read} is not very powerful. - -@<Back up an outer control sequence so that it can be reread@>= -if (cur_cs!=0) - {@+if ((state==token_list)||(name < 1)||(name > 17)) - {@+p=get_avail();info(p)=cs_token_flag+cur_cs; - back_list(p); /*prepare to read the control sequence again*/ - } - cur_cmd=spacer;cur_chr=' '; /*replace it by a space*/ - } - -@ @<Tell the user what has run away...@>= -{@+runaway(); /*print a definition, argument, or preamble*/ -if (cur_cs==0) print_err("File ended"); -@.File ended while scanning...@> -else{@+cur_cs=0;print_err("Forbidden control sequence found"); -@.Forbidden control sequence...@> - } -print(" while scanning "); -@<Print either `\.{definition}' or `\.{use}' or `\.{preamble}' or `\.{text}', and -insert tokens that should lead to recovery@>; -print(" of ");sprint_cs(warning_index); -help4("I suspect you have forgotten a `}', causing me",@/ -"to read past where you wanted me to stop.",@/ -"I'll try to recover; but if the error is serious,",@/ -"you'd better type `E' or `X' now and fix your file.");@/ -error(); -} - -@ The recovery procedure can't be fully understood without knowing more -about the \TeX\ routines that should be aborted, but we can sketch the -ideas here: For a runaway definition or a runaway balanced text -we will insert a right brace; for a -runaway preamble, we will insert a special \.{\\cr} token and a right -brace; and for a runaway argument, we will set |long_state| to -|outer_call| and insert \.{\\par}. - -@<Print either `\.{definition}' or...@>= -p=get_avail(); -switch (scanner_status) { -case defining: {@+print("definition");info(p)=right_brace_token+'}'; - } @+break; -case matching: {@+print("use");info(p)=par_token;long_state=outer_call; - } @+break; -case aligning: {@+print("preamble");info(p)=right_brace_token+'}';q=p; - p=get_avail();link(p)=q;info(p)=cs_token_flag+frozen_cr; - align_state=-1000000; - } @+break; -case absorbing: {@+print("text");info(p)=right_brace_token+'}'; - } -} /*there are no other cases*/ -ins_list(p) - -@ We need to mention a procedure here that may be called by |get_next|. - -@p static void firm_up_the_line(void); - -@ Now we're ready to take the plunge into |get_next| itself. Parts of -this routine are executed more often than any other instructions of \TeX. -@^mastication@>@^inner loop@> - -@p static void get_next(void) /*sets |cur_cmd|, |cur_chr|, |cur_cs| to next token*/ -{@+ /*go here to get the next input token*/ - /*go here to eat the next character from a file*/ - /*go here to digest it again*/ - /*go here to start looking for a control sequence*/ - /*go here when a control sequence has been found*/ - /*go here when the next input token has been got*/ -int k; /*an index into |buffer|*/ -halfword @!t; /*a token*/ -int @!cat; /*|cat_code(cur_chr)|, usually*/ -ASCII_code @!c, @!cc; /*constituents of a possible expanded code*/ -int @!d; /*number of excess characters in an expanded code*/ -restart: cur_cs=0; -if (state!=token_list) -@<Input from external file, |goto restart| if no input found@>@; -else@<Input from token list, |goto restart| if end of list or if a parameter needs -to be expanded@>; -@<If an alignment entry has just ended, take appropriate action@>; -} - -@ An alignment entry ends when a tab or \.{\\cr} occurs, provided that the -current level of braces is the same as the level that was present at the -beginning of that alignment entry; i.e., provided that |align_state| has -returned to the value it had after the \<u_j> template for that entry. -@^inner loop@> - -@<If an alignment entry has just ended, take appropriate action@>= -if (cur_cmd <= car_ret) if (cur_cmd >= tab_mark) if (align_state==0) - @<Insert the \(v)\<v_j> template and |goto restart|@>@; - -@ @<Input from external file, |goto restart| if no input found@>= -@^inner loop@> -{@+get_cur_chr: if (loc <= limit) /*current line not yet finished*/ - {@+cur_chr=buffer[loc];incr(loc); - reswitch: cur_cmd=cat_code(cur_chr); - @<Change state if necessary, and |goto switch| if the current character should be -ignored, or |goto reswitch| if the current character changes to another@>; - } -else{@+state=new_line;@/ - @<Move to next line of file, or |goto restart| if there is no next line, or |return| -if a \.{\\read} line has finished@>; - check_interrupt; - goto get_cur_chr; - } -} - -@ The following 48-way switch accomplishes the scanning quickly, assuming -that a decent \PASCAL\ compiler has translated the code. Note that the numeric -values for |mid_line|, |skip_blanks|, and |new_line| are spaced -apart from each other by |max_char_code+1|, so we can add a character's -command code to the state to get a single number that characterizes both. - -@d any_state_plus(A) case mid_line+A: case skip_blanks+A: case new_line+A - -@<Change state if necessary...@>= -switch (state+cur_cmd) { -@<Cases where character is ignored@>: goto get_cur_chr; -any_state_plus(escape): @<Scan a control sequence and set |state:=skip_blanks| or -|mid_line|@>@;@+break; -any_state_plus(active_char): @<Process an active-character control sequence and set -|state:=mid_line|@>@;@+break; -any_state_plus(sup_mark): @<If this |sup_mark| starts an expanded character like~\.{\^\^A} -or~\.{\^\^df}, then |goto reswitch|, otherwise set |state:=mid_line|@>@;@+break; -any_state_plus(invalid_char): @<Decry the invalid character and |goto restart|@>@; -@t\4@>@<Handle situations involving spaces, braces, changes of state@>@; -default:do_nothing; -} - -@ @<Cases where character is ignored@>= -any_state_plus(ignore): case skip_blanks+spacer: case new_line+spacer - -@ We go to |restart| instead of to |get_cur_chr|, because |state| might equal -|token_list| after the error has been dealt with -(cf.\ |clear_for_error_prompt|). - -@<Decry the invalid...@>= -{@+print_err("Text line contains an invalid character"); -@.Text line contains...@> -help2("A funny symbol that I can't read has just been input.",@/ -"Continue, and I'll forget that it ever happened.");@/ -deletions_allowed=false;error();deletions_allowed=true; -goto restart; -} - -@ @d add_delims_to(A) A+math_shift: A+tab_mark: A+mac_param: - A+sub_mark: A+letter: A+other_char - -@<Handle situations involving spaces, braces, changes of state@>= -case mid_line+spacer: @<Enter |skip_blanks| state, emit a space@>@;@+break; -case mid_line+car_ret: @<Finish line, emit a space@>@;@+break; -case skip_blanks+car_ret: any_state_plus(comment): - @<Finish line, |goto switch|@>@; -case new_line+car_ret: @<Finish line, emit a \.{\\par}@>@;@+break; -case mid_line+left_brace: incr(align_state);@+break; -case skip_blanks+left_brace: case new_line+left_brace: {@+ - state=mid_line;incr(align_state); - } @+break; -case mid_line+right_brace: decr(align_state);@+break; -case skip_blanks+right_brace: case new_line+right_brace: {@+ - state=mid_line;decr(align_state); - } @+break; -add_delims_to(case skip_blanks): add_delims_to(case new_line): state=mid_line;@+break; - -@ When a character of type |spacer| gets through, its character code is -changed to $\.{"\ "}=040$. This means that the ASCII codes for tab and space, -and for the space inserted at the end of a line, will -be treated alike when macro parameters are being matched. We do this -since such characters are indistinguishable on most computer terminal displays. - -@<Finish line, emit a space@>= -{@+loc=limit+1;cur_cmd=spacer;cur_chr=' '; -} - -@ The following code is performed only when |cur_cmd==spacer|. - -@<Enter |skip_blanks| state, emit a space@>= -{@+state=skip_blanks;cur_chr=' '; -} - -@ @<Finish line, |goto switch|@>= -{@+loc=limit+1;goto get_cur_chr; -} - -@ @<Finish line, emit a \.{\\par}@>= -{@+loc=limit+1;cur_cs=par_loc;cur_cmd=eq_type(cur_cs); -cur_chr=equiv(cur_cs); -if (cur_cmd >= outer_call) check_outer_validity(); -} - -@ Notice that a code like \.{\^\^8} becomes \.x if not followed by a hex digit. - -@d is_hex(A) (((A >= '0')&&(A <= '9'))||((A >= 'a')&&(A <= 'f'))) -@d hex_to_cur_chr - if (c <= '9') cur_chr=c-'0';@+else cur_chr=c-'a'+10; - if (cc <= '9') cur_chr=16*cur_chr+cc-'0'; - else cur_chr=16*cur_chr+cc-'a'+10 - -@<If this |sup_mark| starts an expanded character...@>= -{@+if (cur_chr==buffer[loc]) if (loc < limit) - {@+c=buffer[loc+1];@+if (c < 0200) /*yes we have an expanded char*/ - {@+loc=loc+2; - if (is_hex(c)) if (loc <= limit) - {@+cc=buffer[loc];@+if (is_hex(cc)) - {@+incr(loc);hex_to_cur_chr;goto reswitch; - } - } - if (c < 0100) cur_chr=c+0100;@+else cur_chr=c-0100; - goto reswitch; - } - } -state=mid_line; -} - -@ @<Process an active-character...@>= -{@+cur_cs=cur_chr+active_base; -cur_cmd=eq_type(cur_cs);cur_chr=equiv(cur_cs);state=mid_line; -if (cur_cmd >= outer_call) check_outer_validity(); -} - -@ Control sequence names are scanned only when they appear in some line of -a file; once they have been scanned the first time, their |eqtb| location -serves as a unique identification, so \TeX\ doesn't need to refer to the -original name any more except when it prints the equivalent in symbolic form. - -The program that scans a control sequence has been written carefully -in order to avoid the blowups that might otherwise occur if a malicious -user tried something like `\.{\\catcode\'15=0}'. The algorithm might -look at |buffer[limit+1]|, but it never looks at |buffer[limit+2]|. - -If expanded characters like `\.{\^\^A}' or `\.{\^\^df}' -appear in or just following -a control sequence name, they are converted to single characters in the -buffer and the process is repeated, slowly but surely. - -@<Scan a control...@>= -{@+if (loc > limit) cur_cs=null_cs; /*|state| is irrelevant in this case*/ -else{@+start_cs: k=loc;cur_chr=buffer[k];cat=cat_code(cur_chr); - incr(k); - if (cat==letter) state=skip_blanks; - else if (cat==spacer) state=skip_blanks; - else state=mid_line; - if ((cat==letter)&&(k <= limit)) - @<Scan ahead in the buffer until finding a nonletter; if an expanded code is encountered, -reduce it and |goto start_cs|; otherwise if a multiletter control sequence is found, -adjust |cur_cs| and |loc|, and |goto found|@>@; - else@<If an expanded code is present, reduce it and |goto start_cs|@>; - cur_cs=single_base+buffer[loc];incr(loc); - } -found: cur_cmd=eq_type(cur_cs);cur_chr=equiv(cur_cs); -if (cur_cmd >= outer_call) check_outer_validity(); -} - -@ Whenever we reach the following piece of code, we will have -|cur_chr==buffer[k-1]| and |k <= limit+1| and |cat==cat_code(cur_chr)|. If an -expanded code like \.{\^\^A} or \.{\^\^df} appears in |buffer[(k-1)dotdot(k+1)]| -or |buffer[(k-1)dotdot(k+2)]|, we -will store the corresponding code in |buffer[k-1]| and shift the rest of -the buffer left two or three places. - -@<If an expanded...@>= -{@+if (buffer[k]==cur_chr) @+if (cat==sup_mark) @+if (k < limit) - {@+c=buffer[k+1];@+if (c < 0200) /*yes, one is indeed present*/ - {@+d=2; - if (is_hex(c)) @+if (k+2 <= limit) - {@+cc=buffer[k+2];@+if (is_hex(cc)) incr(d); - } - if (d > 2) - {@+hex_to_cur_chr;buffer[k-1]=cur_chr; - } - else if (c < 0100) buffer[k-1]=c+0100; - else buffer[k-1]=c-0100; - limit=limit-d;first=first-d; - while (k <= limit) - {@+buffer[k]=buffer[k+d];incr(k); - } - goto start_cs; - } - } -} - -@ @<Scan ahead in the buffer...@>= -{@+@/do@+{cur_chr=buffer[k];cat=cat_code(cur_chr);incr(k); -}@+ while (!((cat!=letter)||(k > limit))); -@<If an expanded...@>; -if (cat!=letter) decr(k); - /*now |k| points to first nonletter*/ -if (k > loc+1) /*multiletter control sequence has been scanned*/ - {@+cur_cs=id_lookup(loc, k-loc);loc=k;goto found; - } -} - -@ Let's consider now what happens when |get_next| is looking at a token list. - -@<Input from token list, |goto restart| if end of list or if a parameter needs to -be expanded@>= -if (loc!=null) /*list not exhausted*/ -@^inner loop@> - {@+t=info(loc);loc=link(loc); /*move to next*/ - if (t >= cs_token_flag) /*a control sequence token*/ - {@+cur_cs=t-cs_token_flag; - cur_cmd=eq_type(cur_cs);cur_chr=equiv(cur_cs); - if (cur_cmd >= outer_call) - if (cur_cmd==dont_expand) - @<Get the next token, suppressing expansion@>@; - else check_outer_validity(); - } - else{@+cur_cmd=t/0400;cur_chr=t%0400; - switch (cur_cmd) { - case left_brace: incr(align_state);@+break; - case right_brace: decr(align_state);@+break; - case out_param: @<Insert macro parameter and |goto restart|@>@; - default:do_nothing; - } - } - } -else{@+ /*we are done with this token list*/ - end_token_list();goto restart; /*resume previous level*/ - } - -@ The present point in the program is reached only when the |expand| -routine has inserted a special marker into the input. In this special -case, |info(loc)| is known to be a control sequence token, and |link(loc)==null|. - -@d no_expand_flag 257 /*this characterizes a special variant of |relax|*/ - -@<Get the next token, suppressing expansion@>= -{@+cur_cs=info(loc)-cs_token_flag;loc=null;@/ -cur_cmd=eq_type(cur_cs);cur_chr=equiv(cur_cs); -if (cur_cmd > max_command) - {@+cur_cmd=relax;cur_chr=no_expand_flag; - } -} - -@ @<Insert macro parameter...@>= -{@+begin_token_list(param_stack[param_start+cur_chr-1], parameter); -goto restart; -} - -@ All of the easy branches of |get_next| have now been taken care of. -There is one more branch. - -@d end_line_char_inactive (end_line_char < 0)||(end_line_char > 255) - -@<Move to next line of file, or |goto restart|...@>= -if (name > 17) @<Read next line of file into |buffer|, or |goto restart| if the file -has ended@>@; -else{@+if (!terminal_input) /*\.{\\read} line has ended*/ - {@+cur_cmd=0;cur_chr=0;return; - } - if (input_ptr > 0) /*text was inserted during error recovery*/ - {@+end_file_reading();goto restart; /*resume previous level*/ - } - if (selector < log_only) open_log_file(); - if (interaction > nonstop_mode) - {@+if (end_line_char_inactive) incr(limit); - if (limit==start) /*previous line was empty*/ - print_nl("(Please type a command or say `\\end')"); -@.Please type...@> - print_ln();first=start; - prompt_input("*"); /*input on-line into |buffer|*/ -@.*\relax@> - limit=last; - if (end_line_char_inactive) decr(limit); - else buffer[limit]=end_line_char; - first=limit+1; - loc=start; - } - else fatal_error("*** (job aborted, no legal \\end found)"); -@.job aborted@> - /*nonstop mode, which is intended for overnight batch processing, - never waits for on-line input*/ - } - -@ The global variable |force_eof| is normally |false|; it is set |true| -by an \.{\\endinput} command. - -@<Glob...@>= -static bool @!force_eof; /*should the next \.{\\input} be aborted early?*/ - -@ @<Read next line of file into |buffer|, or |goto restart| if the file has ended@>= -{@+incr(line);first=start; -if (!force_eof) - if (name <= 19) - {@+if (pseudo_input()) /*not end of file*/ - firm_up_the_line(); /*this sets |limit|*/ - else if ((every_eof!=null)&&!eof_seen[index]) - {@+limit=first-1;eof_seen[index]=true; /*fake one empty line*/ - begin_token_list(every_eof, every_eof_text);goto restart; - } - else force_eof=true; - } - else - {@+if (input_ln(&cur_file, true)) /*not end of file*/ - firm_up_the_line(); /*this sets |limit|*/ - else if ((every_eof!=null)&&!eof_seen[index]) - {@+limit=first-1;eof_seen[index]=true; /*fake one empty line*/ - begin_token_list(every_eof, every_eof_text);goto restart; - } - else force_eof=true; - } -if (force_eof) - {@+if (tracing_nesting > 0) - if ((grp_stack[in_open]!=cur_boundary)||@| - (if_stack[in_open]!=cond_ptr)) file_warning(); - /*give warning for some unfinished groups and/or conditionals*/ - if (name >= 19) - {@+print_char(')');decr(open_parens); - update_terminal; /*show user that file has been read*/ - } - force_eof=false; - end_file_reading(); /*resume previous level*/ - check_outer_validity();goto restart; - } -if (end_line_char_inactive) decr(limit); -else buffer[limit]=end_line_char; -first=limit+1;loc=start; /*ready to read*/ -} - -@ If the user has set the |pausing| parameter to some positive value, -and if nonstop mode has not been selected, each line of input is displayed -on the terminal and the transcript file, followed by `\.{=>}'. -\TeX\ waits for a response. If the response is simply |carriage_return|, the -line is accepted as it stands, otherwise the line typed is -used instead of the line in the file. - -@p static void firm_up_the_line(void) -{@+int k; /*an index into |buffer|*/ -limit=last; -if (pausing > 0) if (interaction > nonstop_mode) - {@+wake_up_terminal;print_ln(); - if (start < limit) for (k=start; k<=limit-1; k++) printn(buffer[k]); - first=limit;prompt_input("=>"); /*wait for user response*/ -@.=>@> - if (last > first) - {@+for (k=first; k<=last-1; k++) /*move line down in buffer*/ - buffer[k+start-first]=buffer[k]; - limit=start+last-first; - } - } -} - -@ Since |get_next| is used so frequently in \TeX, it is convenient -to define three related procedures that do a little more: - -\yskip\hang|get_token| not only sets |cur_cmd| and |cur_chr|, it -also sets |cur_tok|, a packed halfword version of the current token. - -\yskip\hang|get_x_token|, meaning ``get an expanded token,'' is like -|get_token|, but if the current token turns out to be a user-defined -control sequence (i.e., a macro call), or a conditional, -or something like \.{\\topmark} or \.{\\expandafter} or \.{\\csname}, -it is eliminated from the input by beginning the expansion of the macro -or the evaluation of the conditional. - -\yskip\hang|x_token| is like |get_x_token| except that it assumes that -|get_next| has already been called. - -\yskip\noindent -In fact, these three procedures account for almost every use of |get_next|. - -@ No new control sequences will be defined except during a call of -|get_token|, or when \.{\\csname} compresses a token list, because -|no_new_control_sequence| is always |true| at other times. - -@p static void get_token(void) /*sets |cur_cmd|, |cur_chr|, |cur_tok|*/ -{@+no_new_control_sequence=false;get_next();no_new_control_sequence=true; -@^inner loop@> -if (cur_cs==0) cur_tok=(cur_cmd*0400)+cur_chr; -else cur_tok=cs_token_flag+cur_cs; -} - -@* Expanding the next token. -Only a dozen or so command codes | > max_command| can possibly be returned by -|get_next|; in increasing order, they are |undefined_cs|, |expand_after|, -|no_expand|, |input|, |if_test|, |fi_or_else|, |cs_name|, |convert|, |the|, -|top_bot_mark|, |call|, |long_call|, |outer_call|, |long_outer_call|, and -|end_template|.{\emergencystretch=40pt\par} - -The |expand| subroutine is used when |cur_cmd > max_command|. It removes a -``call'' or a conditional or one of the other special operations just -listed. It follows that |expand| might invoke itself recursively. In all -cases, |expand| destroys the current token, but it sets things up so that -the next |get_next| will deliver the appropriate next token. The value of -|cur_tok| need not be known when |expand| is called. - -Since several of the basic scanning routines communicate via global variables, -their values are saved as local variables of |expand| so that -recursive calls don't invalidate them. -@^recursion@> - -@p @t\4@>@<Declare the procedure called |macro_call|@>@;@/ -@t\4@>@<Declare the procedure called |insert_relax|@>@;@/ -@t\4@>@<Declare \eTeX\ procedures for expanding@>@;@/ -static void pass_text(void); -static void start_input(void); -static void conditional(void); -static void get_x_token(void); -static void conv_toks(void); -static void ins_the_toks(void); -static void expand(void) -{@+ -halfword t; /*token that is being ``expanded after''*/ -pointer @!p, @!q, @!r; /*for list manipulation*/ -int @!j; /*index into |buffer|*/ -int @!cv_backup; /*to save the global quantity |cur_val|*/ -small_number @!cvl_backup, @!radix_backup, @!co_backup; - /*to save |cur_val_level|, etc.*/ -pointer @!backup_backup; /*to save |link(backup_head)|*/ -small_number @!save_scanner_status; /*temporary storage of |scanner_status|*/ -cv_backup=cur_val;cvl_backup=cur_val_level;radix_backup=radix; -co_backup=cur_order;backup_backup=link(backup_head); -reswitch: -if (cur_cmd < call) @<Expand a nonmacro@>@; -else if (cur_cmd < end_template) macro_call(); -else@<Insert a token containing |frozen_endv|@>; -cur_val=cv_backup;cur_val_level=cvl_backup;radix=radix_backup; -cur_order=co_backup;link(backup_head)=backup_backup; -} - -@ @<Expand a nonmacro@>= -{@+if (tracing_commands > 1) show_cur_cmd_chr(); -switch (cur_cmd) { -case top_bot_mark: @<Insert the \(a)appropriate mark text into the scanner@>@;@+break; -case expand_after: if (cur_chr==0) @<Expand the token after the next token@>@; - else@<Negate a boolean conditional and |goto reswitch|@>@;@+break; -case no_expand: @<Suppress expansion of the next token@>@;@+break; -case cs_name: @<Manufacture a control sequence name@>@;@+break; -case convert: conv_toks();@+break; /*this procedure is discussed in Part 27 below*/ -case the: ins_the_toks();@+break; /*this procedure is discussed in Part 27 below*/ -case if_test: conditional();@+break; /*this procedure is discussed in Part 28 below*/ -case fi_or_else: @<Terminate the current conditional and skip to \.{\\fi}@>@;@+break; -case input: @<Initiate or terminate input from a file@>;@+break; -default:@<Complain about an undefined macro@>@; -} -} - -@ It takes only a little shuffling to do what \TeX\ calls \.{\\expandafter}. - -@<Expand the token after...@>= -{@+get_token();t=cur_tok;get_token(); -if (cur_cmd > max_command) expand();@+else back_input(); -cur_tok=t;back_input(); -} - -@ The implementation of \.{\\noexpand} is a bit trickier, because it is -necessary to insert a special `|dont_expand|' marker into \TeX's reading -mechanism. This special marker is processed by |get_next|, but it does -not slow down the inner loop. - -Since \.{\\outer} macros might arise here, we must also -clear the |scanner_status| temporarily. - -@<Suppress expansion...@>= -{@+save_scanner_status=scanner_status;scanner_status=normal; -get_token();scanner_status=save_scanner_status;t=cur_tok; -back_input(); /*now |start| and |loc| point to the backed-up token |t|*/ -if (t >= cs_token_flag) - {@+p=get_avail();info(p)=cs_token_flag+frozen_dont_expand; - link(p)=loc;start=p;loc=p; - } -} - -@ @<Complain about an undefined macro@>= -{@+print_err("Undefined control sequence"); -@.Undefined control sequence@> -help5("The control sequence at the end of the top line",@/ -"of your error message was never \\def'ed. If you have",@/ -"misspelled it (e.g., `\\hobx'), type `I' and the correct",@/ -"spelling (e.g., `I\\hbox'). Otherwise just continue,",@/ -"and I'll forget about whatever was undefined."); -error(); -} - -@ The |expand| procedure and some other routines that construct token -lists find it convenient to use the following macros, which are valid only if -the variables |p| and |q| are reserved for token-list building. - -@d store_new_token(A) {@+q=get_avail();link(p)=q;info(q)=A; - p=q; /*|link(p)| is |null|*/ - } -@d fast_store_new_token(A) {@+fast_get_avail(q);link(p)=q;info(q)=A; - p=q; /*|link(p)| is |null|*/ - } - -@ @<Manufacture a control...@>= -{@+r=get_avail();p=r; /*head of the list of characters*/ -@/do@+{get_x_token(); -if (cur_cs==0) store_new_token(cur_tok); -}@+ while (!(cur_cs!=0)); -if (cur_cmd!=end_cs_name) @<Complain about missing \.{\\endcsname}@>; -@<Look up the characters of list |r| in the hash table, and set |cur_cs|@>; -flush_list(r); -if (eq_type(cur_cs)==undefined_cs) - {@+eq_define(cur_cs, relax, 256); /*N.B.: The |save_stack| might change*/ - } /*the control sequence will now match `\.{\\relax}'*/ -cur_tok=cur_cs+cs_token_flag;back_input(); -} - -@ @<Complain about missing \.{\\endcsname}@>= -{@+print_err("Missing ");print_esc("endcsname");print(" inserted"); -@.Missing \\endcsname...@> -help2("The control sequence marked <to be read again> should",@/ - "not appear between \\csname and \\endcsname."); -back_error(); -} - -@ @<Look up the characters of list |r| in the hash table...@>= -j=first;p=link(r); -while (p!=null) - {@+if (j >= max_buf_stack) - {@+max_buf_stack=j+1; - if (max_buf_stack==buf_size) - overflow("buffer size", buf_size); -@:TeX capacity exceeded buffer size}{\quad buffer size@> - } - buffer[j]=info(p)%0400;incr(j);p=link(p); - } -if (j==first) cur_cs=null_cs; /*the list is empty*/ -else if (j > first+1) - {@+no_new_control_sequence=false;cur_cs=id_lookup(first, j-first); - no_new_control_sequence=true; - } -else cur_cs=single_base+buffer[first] /*the list has length one*/ - -@ An |end_template| command is effectively changed to an |endv| command -by the following code. (The reason for this is discussed below; the -|frozen_end_template| at the end of the template has passed the -|check_outer_validity| test, so its mission of error detection has been -accomplished.) - -@<Insert a token containing |frozen_endv|@>= -{@+cur_tok=cs_token_flag+frozen_endv;back_input(); -} - -@ The processing of \.{\\input} involves the |start_input| subroutine, -which will be declared later; the processing of \.{\\endinput} is trivial. - -@<Put each...@>= -primitive("input", input, 0);@/ -@!@:input\_}{\.{\\input} primitive@> -primitive("endinput", input, 1);@/ -@!@:end\_input\_}{\.{\\endinput} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case input: if (chr_code==0) print_esc("input") - @/@<Cases of |input| for |print_cmd_chr|@>;@/ - else print_esc("endinput");@+break; - -@ @<Initiate or terminate input...@>= -if (cur_chr==1) force_eof=true -@/@<Cases for |input|@>;@/ -else if (name_in_progress) insert_relax(); -else start_input() - -@ Sometimes the expansion looks too far ahead, so we want to insert -a harmless \.{\\relax} into the user's input. - -@<Declare the procedure called |insert_relax|@>= -static void insert_relax(void) -{@+cur_tok=cs_token_flag+cur_cs;back_input(); -cur_tok=cs_token_flag+frozen_relax;back_input();token_type=inserted; -} - -@ Here is a recursive procedure that is \TeX's usual way to get the -next token of input. It has been slightly optimized to take account of -common cases. - -@p static void get_x_token(void) /*sets |cur_cmd|, |cur_chr|, |cur_tok|, - and expands macros*/ -{@+ -restart: get_next(); -@^inner loop@> -if (cur_cmd <= max_command) goto done; -if (cur_cmd >= call) - if (cur_cmd < end_template) macro_call(); - else{@+cur_cs=frozen_endv;cur_cmd=endv; - goto done; /*|cur_chr==null_list|*/ - } -else expand(); -goto restart; -done: if (cur_cs==0) cur_tok=(cur_cmd*0400)+cur_chr; -else cur_tok=cs_token_flag+cur_cs; -} - -@ The |get_x_token| procedure is essentially equivalent to two consecutive -procedure calls: |get_next;x_token|. - -@p static void x_token(void) /*|get_x_token| without the initial |get_next|*/ -{@+while (cur_cmd > max_command) - {@+expand(); - get_next(); - } -if (cur_cs==0) cur_tok=(cur_cmd*0400)+cur_chr; -else cur_tok=cs_token_flag+cur_cs; -} - -@ A control sequence that has been \.{\\def}'ed by the user is expanded by -\TeX's |macro_call| procedure. - -Before we get into the details of |macro_call|, however, let's consider the -treatment of primitives like \.{\\topmark}, since they are essentially -macros without parameters. The token lists for such marks are kept in a -global array of five pointers; we refer to the individual entries of this -array by symbolic names |top_mark|, etc. The value of |top_mark| is either -|null| or a pointer to the reference count of a token list. - -@d top_mark_code 0 /*the mark in effect at the previous page break*/ -@d first_mark_code 1 /*the first mark between |top_mark| and |bot_mark|*/ -@d bot_mark_code 2 /*the mark in effect at the current page break*/ -@d split_first_mark_code 3 /*the first mark found by \.{\\vsplit}*/ -@d split_bot_mark_code 4 /*the last mark found by \.{\\vsplit}*/ -@d top_mark cur_mark[top_mark_code] -@d first_mark cur_mark[first_mark_code] -@d bot_mark cur_mark[bot_mark_code] -@d split_first_mark cur_mark[split_first_mark_code] -@d split_bot_mark cur_mark[split_bot_mark_code] - -@<Glob...@>= -pointer @!cur_mark0[split_bot_mark_code-top_mark_code+1], *const @!cur_mark = @!cur_mark0-top_mark_code; - /*token lists for marks*/ - -@ @<Set init...@>= -top_mark=null;first_mark=null;bot_mark=null; -split_first_mark=null;split_bot_mark=null; - -@ @<Put each...@>= -primitive("topmark", top_bot_mark, top_mark_code); -@!@:top\_mark\_}{\.{\\topmark} primitive@> -primitive("firstmark", top_bot_mark, first_mark_code); -@!@:first\_mark\_}{\.{\\firstmark} primitive@> -primitive("botmark", top_bot_mark, bot_mark_code); -@!@:bot\_mark\_}{\.{\\botmark} primitive@> -primitive("splitfirstmark", top_bot_mark, split_first_mark_code); -@!@:split\_first\_mark\_}{\.{\\splitfirstmark} primitive@> -primitive("splitbotmark", top_bot_mark, split_bot_mark_code); -@!@:split\_bot\_mark\_}{\.{\\splitbotmark} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case top_bot_mark: switch (chr_code) { - case first_mark_code: print_esc("firstmark");@+break; - case bot_mark_code: print_esc("botmark");@+break; - case split_first_mark_code: print_esc("splitfirstmark");@+break; - case split_bot_mark_code: print_esc("splitbotmark");@+break; - default:print_esc("topmark"); - } @+break; - -@ The following code is activated when |cur_cmd==top_bot_mark| and -when |cur_chr| is a code like |top_mark_code|. - -@<Insert the \(a)appropriate mark text into the scanner@>= -{@+if (cur_mark[cur_chr]!=null) - begin_token_list(cur_mark[cur_chr], mark_text); -} - -@ Now let's consider |macro_call| itself, which is invoked when \TeX\ is -scanning a control sequence whose |cur_cmd| is either |call|, |long_call|, -|outer_call|, or |long_outer_call|. The control sequence definition -appears in the token list whose reference count is in location |cur_chr| -of |mem|. - -The global variable |long_state| will be set to |call| or to |long_call|, -depending on whether or not the control sequence disallows \.{\\par} -in its parameters. The |get_next| routine will set |long_state| to -|outer_call| and emit \.{\\par}, if a file ends or if an \.{\\outer} -control sequence occurs in the midst of an argument. - -@<Glob...@>= -static int @!long_state; /*governs the acceptance of \.{\\par}*/ - -@ The parameters, if any, must be scanned before the macro is expanded. -Parameters are token lists without reference counts. They are placed on -an auxiliary stack called |pstack| while they are being scanned, since -the |param_stack| may be losing entries during the matching process. -(Note that |param_stack| can't be gaining entries, since |macro_call| is -the only routine that puts anything onto |param_stack|, and it -is not recursive.) - -@<Glob...@>= -static pointer @!pstack[9]; /*arguments supplied to a macro*/ - -@ After parameter scanning is complete, the parameters are moved to the -|param_stack|. Then the macro body is fed to the scanner; in other words, -|macro_call| places the defined text of the control sequence at the -top of\/ \TeX's input stack, so that |get_next| will proceed to read it -next. - -The global variable |cur_cs| contains the |eqtb| address of the control sequence -being expanded, when |macro_call| begins. If this control sequence has not been -declared \.{\\long}, i.e., if its command code in the |eq_type| field is -not |long_call| or |long_outer_call|, its parameters are not allowed to contain -the control sequence \.{\\par}. If an illegal \.{\\par} appears, the macro -call is aborted, and the \.{\\par} will be rescanned. - -@<Declare the procedure called |macro_call|@>= -static void macro_call(void) /*invokes a user-defined control sequence*/ -{@+ -pointer r; /*current node in the macro's token list*/ -pointer @!p; /*current node in parameter token list being built*/ -pointer @!q; /*new node being put into the token list*/ -pointer @!s; /*backup pointer for parameter matching*/ -pointer @!t; /*cycle pointer for backup recovery*/ -pointer @!u, @!v; /*auxiliary pointers for backup recovery*/ -pointer @!rbrace_ptr; /*one step before the last |right_brace| token*/ -small_number @!n; /*the number of parameters scanned*/ -halfword @!unbalance; /*unmatched left braces in current parameter*/ -int @!m; /*the number of tokens or groups (usually)*/ -pointer @!ref_count; /*start of the token list*/ -small_number @!save_scanner_status; /*|scanner_status| upon entry*/ -pointer @!save_warning_index; /*|warning_index| upon entry*/ -ASCII_code @!match_chr; /*character used in parameter*/ -save_scanner_status=scanner_status;save_warning_index=warning_index; -warning_index=cur_cs;ref_count=cur_chr;r=link(ref_count);n=0; -if (tracing_macros > 0) @<Show the text of the macro being expanded@>; -if (info(r)==protected_token) r=link(r); -if (info(r)!=end_match_token) - @<Scan the parameters and make |link(r)| point to the macro body; but |return| if -an illegal \.{\\par} is detected@>; -@<Feed the macro body and its parameters to the scanner@>; -end: scanner_status=save_scanner_status;warning_index=save_warning_index; -} - -@ Before we put a new token list on the input stack, it is wise to clean off -all token lists that have recently been depleted. Then a user macro that ends -with a call to itself will not require unbounded stack space. - -@<Feed the macro body and its parameters to the scanner@>= -while ((state==token_list)&&(loc==null)&&(token_type!=v_template)) - end_token_list(); /*conserve stack space*/ -begin_token_list(ref_count, macro);name=warning_index;loc=link(r); -if (n > 0) - {@+if (param_ptr+n > max_param_stack) - {@+max_param_stack=param_ptr+n; - if (max_param_stack > param_size) - overflow("parameter stack size", param_size); -@:TeX capacity exceeded parameter stack size}{\quad parameter stack size@> - } - for (m=0; m<=n-1; m++) param_stack[param_ptr+m]=pstack[m]; - param_ptr=param_ptr+n; - } - -@ At this point, the reader will find it advisable to review the explanation -of token list format that was presented earlier, since many aspects of that -format are of importance chiefly in the |macro_call| routine. - -The token list might begin with a string of compulsory tokens before the -first |match| or |end_match|. In that case the macro name is supposed to be -followed by those tokens; the following program will set |s==null| to -represent this restriction. Otherwise |s| will be set to the first token of -a string that will delimit the next parameter. - -@<Scan the parameters and make |link(r)| point to the macro body...@>= -{@+scanner_status=matching;unbalance=0; -long_state=eq_type(cur_cs); -if (long_state >= outer_call) long_state=long_state-2; -@/do@+{link(temp_head)=null; -if ((info(r) > match_token+255)||(info(r) < match_token)) s=null; -else{@+match_chr=info(r)-match_token;s=link(r);r=s; - p=temp_head;m=0; - } -@<Scan a parameter until its delimiter string has been found; or, if |s=null|, simply -scan the delimiter string@>;@/ - /*now |info(r)| is a token whose command code is either |match| or |end_match|*/ -}@+ while (!(info(r)==end_match_token)); -} - -@ If |info(r)| is a |match| or |end_match| command, it cannot be equal to -any token found by |get_token|. Therefore an undelimited parameter---i.e., -a |match| that is immediately followed by |match| or |end_match|---will -always fail the test `|cur_tok==info(r)|' in the following algorithm. - -@<Scan a parameter until its delimiter string has been found; or,...@>= -resume: get_token(); /*set |cur_tok| to the next token of input*/ -if (cur_tok==info(r)) - @<Advance \(r)|r|; |goto found| if the parameter delimiter has been fully matched, -otherwise |goto continue|@>; -@<Contribute the recently matched tokens to the current parameter, and |goto continue| -if a partial match is still in effect; but abort if |s=null|@>; -if (cur_tok==par_token) if (long_state!=long_call) - @<Report a runaway argument and abort@>; -if (cur_tok < right_brace_limit) - if (cur_tok < left_brace_limit) - @<Contribute an entire group to the current parameter@>@; - else@<Report an extra right brace and |goto continue|@>@; -else@<Store the current token, but |goto continue| if it is a blank space that would -become an undelimited parameter@>; -incr(m); -if (info(r) > end_match_token) goto resume; -if (info(r) < match_token) goto resume; -found: if (s!=null) @<Tidy up the parameter just scanned, and tuck it away@>@; - -@ @<Store the current token, but |goto continue| if it is...@>= -{@+if (cur_tok==space_token) - if (info(r) <= end_match_token) - if (info(r) >= match_token) goto resume; -store_new_token(cur_tok); -} - -@ A slightly subtle point arises here: When the parameter delimiter ends -with `\.{\#\{}', the token list will have a left brace both before and -after the |end_match|\kern-.4pt. Only one of these should affect the -|align_state|, but both will be scanned, so we must make a correction. - -@<Advance \(r)|r|; |goto found| if the parameter delimiter has been fully...@>= -{@+r=link(r); -if ((info(r) >= match_token)&&(info(r) <= end_match_token)) - {@+if (cur_tok < left_brace_limit) decr(align_state); - goto found; - } -else goto resume; -} - -@ @<Report an extra right brace and |goto continue|@>= -{@+back_input();print_err("Argument of ");sprint_cs(warning_index); -@.Argument of \\x has...@> -print(" has an extra }"); -help6("I've run across a `}' that doesn't seem to match anything.",@/ - "For example, `\\def\\a#1{...}' and `\\a}' would produce",@/ - "this error. If you simply proceed now, the `\\par' that",@/ - "I've just inserted will cause me to report a runaway",@/ - "argument that might be the root of the problem. But if",@/ - "your `}' was spurious, just type `2' and it will go away."); -incr(align_state);long_state=call;cur_tok=par_token;ins_error(); -goto resume; -} /*a white lie; the \.{\\par} won't always trigger a runaway*/ - -@ If |long_state==outer_call|, a runaway argument has already been reported. - -@<Report a runaway argument and abort@>= -{@+if (long_state==call) - {@+runaway();print_err("Paragraph ended before "); -@.Paragraph ended before...@> - sprint_cs(warning_index);print(" was complete"); - help3("I suspect you've forgotten a `}', causing me to apply this",@/ - "control sequence to too much text. How can we recover?",@/ - "My plan is to forget the whole thing and hope for the best."); - back_error(); - } -pstack[n]=link(temp_head);align_state=align_state-unbalance; -for (m=0; m<=n; m++) flush_list(pstack[m]); -goto end; -} - -@ When the following code becomes active, we have matched tokens from |s| to -the predecessor of |r|, and we have found that |cur_tok!=info(r)|. An -interesting situation now presents itself: If the parameter is to be -delimited by a string such as `\.{ab}', and if we have scanned `\.{aa}', -we want to contribute one `\.a' to the current parameter and resume -looking for a `\.b'. The program must account for such partial matches and -for others that can be quite complex. But most of the time we have |s==r| -and nothing needs to be done. - -Incidentally, it is possible for \.{\\par} tokens to sneak in to certain -parameters of non-\.{\\long} macros. For example, consider a case like -`\.{\\def\\a\#1\\par!\{...\}}' where the first \.{\\par} is not followed -by an exclamation point. In such situations it does not seem appropriate -to prohibit the \.{\\par}, so \TeX\ keeps quiet about this bending of -the rules. - -@<Contribute the recently matched tokens to the current parameter...@>= -if (s!=r) - if (s==null) @<Report an improper use of the macro and abort@>@; - else{@+t=s; - @/do@+{store_new_token(info(t));incr(m);u=link(t);v=s; - loop@+{@+if (u==r) - if (cur_tok!=info(v)) goto done; - else{@+r=link(v);goto resume; - } - if (info(u)!=info(v)) goto done; - u=link(u);v=link(v); - } - done: t=link(t); - }@+ while (!(t==r)); - r=s; /*at this point, no tokens are recently matched*/ - } - -@ @<Report an improper use...@>= -{@+print_err("Use of ");sprint_cs(warning_index); -@.Use of x doesn't match...@> -print(" doesn't match its definition"); -help4("If you say, e.g., `\\def\\a1{...}', then you must always",@/ - "put `1' after `\\a', since control sequence names are",@/ - "made up of letters only. The macro here has not been",@/ - "followed by the required stuff, so I'm ignoring it."); -error();goto end; -} - -@ @<Contribute an entire group to the current parameter@>= -{@+unbalance=1; -@^inner loop@> -loop@+{@+fast_store_new_token(cur_tok);get_token(); - if (cur_tok==par_token) if (long_state!=long_call) - @<Report a runaway argument and abort@>; - if (cur_tok < right_brace_limit) - if (cur_tok < left_brace_limit) incr(unbalance); - else{@+decr(unbalance); - if (unbalance==0) goto done1; - } - } -done1: rbrace_ptr=p;store_new_token(cur_tok); -} - -@ If the parameter consists of a single group enclosed in braces, we must -strip off the enclosing braces. That's why |rbrace_ptr| was introduced. - -@<Tidy up the parameter just scanned, and tuck it away@>= -{@+if ((m==1)&&(info(p) < right_brace_limit)) - {@+link(rbrace_ptr)=null;free_avail(p); - p=link(temp_head);pstack[n]=link(p);free_avail(p); - } -else pstack[n]=link(temp_head); -incr(n); -if (tracing_macros > 0) - {@+begin_diagnostic();print_nl("");printn(match_chr);print_int(n); - print("<-");show_token_list(pstack[n-1], null, 1000); - end_diagnostic(false); - } -} - -@ @<Show the text of the macro being expanded@>= -{@+begin_diagnostic();print_ln();print_cs(warning_index); -token_show(ref_count);end_diagnostic(false); -} - -@* Basic scanning subroutines. -Let's turn now to some procedures that \TeX\ calls upon frequently to digest -certain kinds of patterns in the input. Most of these are quite simple; -some are quite elaborate. Almost all of the routines call |get_x_token|, -which can cause them to be invoked recursively. -@^stomach@> -@^recursion@> - -@ The |scan_left_brace| routine is called when a left brace is supposed to be -the next non-blank token. (The term ``left brace'' means, more precisely, -a character whose catcode is |left_brace|.) \TeX\ allows \.{\\relax} to -appear before the |left_brace|. - -@p void scan_left_brace(void) /*reads a mandatory |left_brace|*/ -{@+@<Get the next non-blank non-relax non-call token@>; -if (cur_cmd!=left_brace) - {@+print_err("Missing { inserted"); -@.Missing \{ inserted@> - help4("A left brace was mandatory here, so I've put one in.",@/ - "You might want to delete and/or insert some corrections",@/ - "so that I will find a matching right brace soon.",@/ - "(If you're confused by all this, try typing `I}' now.)"); - back_error();cur_tok=left_brace_token+'{';cur_cmd=left_brace; - cur_chr='{';incr(align_state); - } -} - -@ @<Get the next non-blank non-relax non-call token@>= -@/do@+{get_x_token(); -}@+ while (!((cur_cmd!=spacer)&&(cur_cmd!=relax))) - -@ The |scan_optional_equals| routine looks for an optional `\.=' sign preceded -by optional spaces; `\.{\\relax}' is not ignored here. - -@p static void scan_optional_equals(void) -{@+@<Get the next non-blank non-call token@>; -if (cur_tok!=other_token+'=') back_input(); -} - -@ @<Get the next non-blank non-call token@>= -@/do@+{get_x_token(); -}@+ while (!(cur_cmd!=spacer)) - -@ In case you are getting bored, here is a slightly less trivial routine: -Given a string of lowercase letters, like `\.{pt}' or `\.{plus}' or -`\.{width}', the |scan_keyword| routine checks to see whether the next -tokens of input match this string. The match must be exact, except that -uppercase letters will match their lowercase counterparts; uppercase -equivalents are determined by subtracting |'a'-'A'|, rather than using the -|uc_code| table, since \TeX\ uses this routine only for its own limited -set of keywords. - -If a match is found, the characters are effectively removed from the input -and |true| is returned. Otherwise |false| is returned, and the input -is left essentially unchanged (except for the fact that some macros -may have been expanded, etc.). -@^inner loop@> - -@p static bool scan_keyword(char *@!s) /*look for a given string*/ -{@+ -pointer p; /*tail of the backup list*/ -pointer @!q; /*new node being added to the token list via |store_new_token|*/ -p=backup_head;link(p)=null; -while (*s!=0) - {@+get_x_token(); /*recursion is possible here*/ -@^recursion@> - if ((cur_cs==0)&&@| - ((cur_chr==so(*s))||(cur_chr==so(*s)-'a'+'A'))) - {@+store_new_token(cur_tok);incr(s); - } - else if ((cur_cmd!=spacer)||(p!=backup_head)) - {@+back_input(); - if (p!=backup_head) back_list(link(backup_head)); - return false; - } - } -flush_list(link(backup_head));return true; -} - -@ Here is a procedure that sounds an alarm when mu and non-mu units -are being switched. - -@p static void mu_error(void) -{@+print_err("Incompatible glue units"); -@.Incompatible glue units@> -help1("I'm going to assume that 1mu=1pt when they're mixed."); -error(); -} - -@ The next routine `|scan_something_internal|' is used to fetch internal -numeric quantities like `\.{\\hsize}', and also to handle the `\.{\\the}' -when expanding constructions like `\.{\\the\\toks0}' and -`\.{\\the\\baselineskip}'. Soon we will be considering the |scan_int| -procedure, which calls |scan_something_internal|; on the other hand, -|scan_something_internal| also calls |scan_int|, for constructions like -`\.{\\catcode\`\\\$}' or `\.{\\fontdimen} \.3 \.{\\ff}'. So we -have to declare |scan_int| as a |forward| procedure. A few other -procedures are also declared at this point. - -@p static void scan_int(void); /*scans an integer value*/ -@t\4\4@>@<Declare procedures that scan restricted classes of integers@>@; -@t\4\4@>@<Declare \eTeX\ procedures for scanning@>@; -@t\4\4@>@<Declare procedures that scan font-related stuff@>@; - -@ \TeX\ doesn't know exactly what to expect when |scan_something_internal| -begins. For example, an integer or dimension or glue value could occur -immediately after `\.{\\hskip}'; and one can even say \.{\\the} with -respect to token lists in constructions like -`\.{\\xdef\\o\{\\the\\output\}}'. On the other hand, only integers are -allowed after a construction like `\.{\\count}'. To handle the various -possibilities, |scan_something_internal| has a |level| parameter, which -tells the ``highest'' kind of quantity that |scan_something_internal| is -allowed to produce. Six levels are distinguished, namely |int_val|, -|dimen_val|, |glue_val|, |mu_val|, |ident_val|, and |tok_val|. - -The output of |scan_something_internal| (and of the other routines -|scan_int|, |scan_dimen|, and |scan_glue| below) is put into the global -variable |cur_val|, and its level is put into |cur_val_level|. The highest -values of |cur_val_level| are special: |mu_val| is used only when -|cur_val| points to something in a ``muskip'' register, or to one of the -three parameters \.{\\thinmuskip}, \.{\\medmuskip}, \.{\\thickmuskip}; -|ident_val| is used only when |cur_val| points to a font identifier; -|tok_val| is used only when |cur_val| points to |null| or to the reference -count of a token list. The last two cases are allowed only when -|scan_something_internal| is called with |level==tok_val|. - -If the output is glue, |cur_val| will point to a glue specification, and -the reference count of that glue will have been updated to reflect this -reference; if the output is a nonempty token list, |cur_val| will point to -its reference count, but in this case the count will not have been updated. -Otherwise |cur_val| will contain the integer or scaled value in question. - -@d int_val 0 /*integer values*/ -@d dimen_val 1 /*dimension values*/ -@d glue_val 2 /*glue specifications*/ -@d mu_val 3 /*math glue specifications*/ -@d ident_val 4 /*font identifier*/ -@d tok_val 5 /*token lists*/ -@d has_factor (cur_hfactor!=0 || cur_vfactor!=0) - -@<Glob...@>= -static int @!cur_val, @!cur_hfactor, @!cur_vfactor; /*value returned by numeric scanners*/ -static int @!cur_val_level; /*the ``level'' of this value*/ - -@ The hash table is initialized with `\.{\\count}', `\.{\\dimen}', `\.{\\skip}', -and `\.{\\muskip}' all having |internal_register| as their command code; they are -distinguished by the |chr_code|, which is either |int_val|, |dimen_val|, -|glue_val|, or |mu_val| more than |mem_bot| (dynamic variable-size nodes -cannot have these values) - -@<Put each...@>= -primitive("count", internal_register, mem_bot+int_val); -@!@:count\_}{\.{\\count} primitive@> -primitive("dimen", internal_register, mem_bot+dimen_val); -@!@:dimen\_}{\.{\\dimen} primitive@> -primitive("skip", internal_register, mem_bot+glue_val); -@!@:skip\_}{\.{\\skip} primitive@> -primitive("muskip", internal_register, mem_bot+mu_val); -@!@:mu\_skip\_}{\.{\\muskip} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case internal_register: @<Cases of |register| for |print_cmd_chr|@>@;@+break; - -@ OK, we're ready for |scan_something_internal| itself. A second parameter, -|negative|, is set |true| if the value that is found should be negated. -It is assumed that |cur_cmd| and |cur_chr| represent the first token of -the internal quantity to be scanned; an error will be signalled if -|cur_cmd < min_internal| or |cur_cmd > max_internal|. - -@d scanned_result(A, B) @+{@+cur_val=A;cur_val_level=B;@+} - -@p static void scan_something_internal(small_number @!level, bool @!negative) - /*fetch an internal parameter*/ -{@+ -halfword m; /*|chr_code| part of the operand token*/ -pointer @!q, @!r; /*general purpose indices*/ -pointer @!tx; /*effective tail node*/ -four_quarters @!i; /*character info*/ -int @!p; /*index into |nest|*/ -m=cur_chr; -switch (cur_cmd) { -case def_code: @<Fetch a character code from some table@>@;@+break; -case toks_register: case assign_toks: case def_family: case set_font: case def_font: @<Fetch -a token list or font identifier, provided that |level=tok_val|@>@;@+break; -case assign_int: scanned_result(eqtb[m].i, int_val)@;@+break; -case assign_dimen: - scanned_result(eqtb[m].sc, dimen_val); - if (m>=dimen_base)@/ - { cur_hfactor=hfactor_eqtb[m].sc;@+ - cur_vfactor=vfactor_eqtb[m].sc;@+ - } - else - cur_hfactor=cur_vfactor=0;@/ - @+break; -case assign_glue: scanned_result(equiv(m), glue_val)@;@+break; -case assign_mu_glue: scanned_result(equiv(m), mu_val)@;@+break; -case set_aux: @<Fetch the |space_factor| or the |prev_depth|@>@;@+break; -case set_prev_graf: @<Fetch the |prev_graf|@>@;@+break; -case set_page_int: @<Fetch the |dead_cycles| or the |insert_penalties|@>@;@+break; -case set_page_dimen: @<Fetch something on the |page_so_far|@>@;@+break; -case set_shape: @<Fetch the |par_shape| size@>@;@+break; -case set_box_dimen: @<Fetch a box dimension@>@;@+break; -case char_given: case math_given: scanned_result(cur_chr, int_val)@;@+break; -case assign_font_dimen: @<Fetch a font dimension@>@;@+break; -case assign_font_int: @<Fetch a font integer@>@;@+break; -case internal_register: @<Fetch a register@>@;@+break; -case last_item: @<Fetch an item in the current node, if appropriate@>@;@+break; -default:@<Complain that \.{\\the} can't do this; give zero result@>@; -} @/ -while (cur_val_level > level) @<Convert \(c)|cur_val| to a lower level@>; -@<Fix the reference count, if any, and negate |cur_val| if |negative|@>; -} - -@ @<Fetch a character code from some table@>= -{@+scan_char_num(); -if (m==math_code_base) scanned_result(ho(math_code(cur_val)), int_val)@; -else if (m < math_code_base) scanned_result(equiv(m+cur_val), int_val)@; -else scanned_result(eqtb[m+cur_val].i, int_val); -} - -@ @<Fetch a token list...@>= -if (level!=tok_val) - {@+print_err("Missing number, treated as zero"); -@.Missing number...@> - help3("A number should have been here; I inserted `0'.",@/ - "(If you can't figure out why I needed to see a number,",@/ - "look up `weird error' in the index to The TeXbook.)"); -@:TeXbook}{\sl The \TeX book@> - back_error();scanned_result(0, dimen_val); - } -else if (cur_cmd <= assign_toks) - {@+if (cur_cmd < assign_toks) /*|cur_cmd==toks_register|*/ - if (m==mem_bot) - {@+scan_register_num(); - if (cur_val < 256) cur_val=equiv(toks_base+cur_val); - else{@+find_sa_element(tok_val, cur_val, false); - if (cur_ptr==null) cur_val=null; - else cur_val=sa_ptr(cur_ptr); - } - } - else cur_val=sa_ptr(m); - else cur_val=equiv(m); - cur_val_level=tok_val; - } -else{@+back_input();scan_font_ident(); - scanned_result(font_id_base+cur_val, ident_val); - } - -@ Users refer to `\.{\\the\\spacefactor}' only in horizontal -mode, and to `\.{\\the\\prevdepth}' only in vertical mode; so we put the -associated mode in the modifier part of the |set_aux| command. -The |set_page_int| command has modifier 0 or 1, for `\.{\\deadcycles}' and -`\.{\\insertpenalties}', respectively. The |set_box_dimen| command is -modified by either |width_offset|, |height_offset|, or |depth_offset|. -And the |last_item| command is modified by either |int_val|, |dimen_val|, -|glue_val|, |input_line_no_code|, or |badness_code|. -\eTeX\ inserts |last_node_type_code| after |glue_val| and adds -the codes for its extensions: |eTeX_version_code|, \dots\ . - -@d last_node_type_code (glue_val+1) /*code for \.{\\lastnodetype}*/ -@d input_line_no_code (glue_val+2) /*code for \.{\\inputlineno}*/ -@d badness_code (input_line_no_code+1) /*code for \.{\\badness}*/ -@# -@d eTeX_int (badness_code+1) /*first of \eTeX\ codes for integers*/ -@d eTeX_dim (eTeX_int+8) /*first of \eTeX\ codes for dimensions*/ -@d eTeX_glue (eTeX_dim+9) /*first of \eTeX\ codes for glue*/ -@d eTeX_mu (eTeX_glue+1) /*first of \eTeX\ codes for muglue*/ -@d eTeX_expr (eTeX_mu+1) /*first of \eTeX\ codes for expressions*/ - -@<Put each...@>= -primitive("spacefactor", set_aux, hmode); -@!@:space\_factor\_}{\.{\\spacefactor} primitive@> -primitive("prevdepth", set_aux, vmode);@/ -@!@:prev\_depth\_}{\.{\\prevdepth} primitive@> -primitive("deadcycles", set_page_int, 0); -@!@:dead\_cycles\_}{\.{\\deadcycles} primitive@> -primitive("insertpenalties", set_page_int, 1); -@!@:insert\_penalties\_}{\.{\\insertpenalties} primitive@> -primitive("wd", set_box_dimen, width_offset); -@!@:wd\_}{\.{\\wd} primitive@> -primitive("ht", set_box_dimen, height_offset); -@!@:ht\_}{\.{\\ht} primitive@> -primitive("dp", set_box_dimen, depth_offset); -@!@:dp\_}{\.{\\dp} primitive@> -primitive("lastpenalty", last_item, int_val); -@!@:last\_penalty\_}{\.{\\lastpenalty} primitive@> -primitive("lastkern", last_item, dimen_val); -@!@:last\_kern\_}{\.{\\lastkern} primitive@> -primitive("lastskip", last_item, glue_val); -@!@:last\_skip\_}{\.{\\lastskip} primitive@> -primitive("inputlineno", last_item, input_line_no_code); -@!@:input\_line\_no\_}{\.{\\inputlineno} primitive@> -primitive("badness", last_item, badness_code); -@!@:badness\_}{\.{\\badness} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case set_aux: if (chr_code==vmode) print_esc("prevdepth"); -@+else print_esc("spacefactor");@+break; -case set_page_int: if (chr_code==0) print_esc("deadcycles") -@/@<Cases of |set_page_int| for |print_cmd_chr|@>;@/ -@+else print_esc("insertpenalties");@+break; -case set_box_dimen: if (chr_code==width_offset) print_esc("wd"); -else if (chr_code==height_offset) print_esc("ht"); -else print_esc("dp");@+break; -case last_item: switch (chr_code) { - case int_val: print_esc("lastpenalty");@+break; - case dimen_val: print_esc("lastkern");@+break; - case glue_val: print_esc("lastskip");@+break; - case input_line_no_code: print_esc("inputlineno");@+break; - @/@<Cases of |last_item| for |print_cmd_chr|@>@/ - default:print_esc("badness"); - } @+break; - -@ @<Fetch the |space_factor| or the |prev_depth|@>= -if (abs(mode)!=m) - {@+print_err("Improper ");print_cmd_chr(set_aux, m); -@.Improper \\spacefactor@> -@.Improper \\prevdepth@> - help4("You can refer to \\spacefactor only in horizontal mode;",@/ - "you can refer to \\prevdepth only in vertical mode; and",@/ - "neither of these is meaningful inside \\write. So",@/ - "I'm forgetting what you said and using zero instead."); - error(); - if (level!=tok_val) scanned_result(0, dimen_val)@; - else scanned_result(0, int_val); - } -else if (m==vmode) scanned_result(prev_depth, dimen_val)@; -else scanned_result(space_factor, int_val) - -@ @<Fetch the |dead_cycles| or the |insert_penalties|@>= -{@+if (m==0) cur_val=dead_cycles -@/@<Cases for `Fetch the |dead_cycles| or the |insert_penalties|'@>;@/ -else cur_val=insert_penalties; -cur_val_level=int_val; -} - -@ @<Fetch a box dimension@>= -{@+scan_register_num();fetch_box(q); -if (q==null) cur_val=0;@+else cur_val=mem[q+m].sc; -cur_val_level=dimen_val; -} - -@ Inside an \.{\\output} routine, a user may wish to look at the page totals -that were present at the moment when output was triggered. - -@d max_dimen 07777777777 /*$2^{30}-1$*/ - -@<Fetch something on the |page_so_far|@>= -{@+if ((page_contents==empty)&&(!output_active)) - if (m==0) cur_val=max_dimen;@+else cur_val=0; -else cur_val=page_so_far[m]; -cur_val_level=dimen_val; -} - -@ @<Fetch the |prev_graf|@>= -if (mode==0) scanned_result(0, int_val)@; /*|prev_graf==0| within \.{\\write}*/ -else{@+nest[nest_ptr]=cur_list;p=nest_ptr; - while (abs(nest[p].mode_field)!=vmode) decr(p); - scanned_result(nest[p].pg_field, int_val); - } - -@ @<Fetch the |par_shape| size@>= -{@+if (m > par_shape_loc) @<Fetch a penalties array element@>@; -else if (par_shape_ptr==null) cur_val=0; -else cur_val=info(par_shape_ptr); -cur_val_level=int_val; -} - -@ Here is where \.{\\lastpenalty}, \.{\\lastkern}, \.{\\lastskip}, and -\.{\\lastnodetype} are -implemented. The reference count for \.{\\lastskip} will be updated later. - -We also handle \.{\\inputlineno} and \.{\\badness} here, because they are -legal in similar contexts. - -@<Fetch an item in the current node...@>= -if (m >= input_line_no_code) - if (m >= eTeX_glue) @<Process an expression and |return|@>@; - else if (m >= eTeX_dim) - {@+switch (m) { - @/@<Cases for fetching a dimension value@>@/ - } /*there are no other cases*/ - cur_val_level=dimen_val; - } - else{@+switch (m) { - case input_line_no_code: cur_val=line;@+break; - case badness_code: cur_val=last_badness;@+break; - @/@<Cases for fetching an integer value@>@/ - } /*there are no other cases*/ - cur_val_level=int_val; - } -else{@+if (cur_chr==glue_val) cur_val=zero_glue;@+else cur_val=0; - cur_val_level=cur_chr; - if (!is_char_node(tail)&&(mode!=0)) - switch (cur_chr) { - case int_val: if (type(tail)==penalty_node) cur_val=penalty(tail);@+break; - case dimen_val: if (type(tail)==kern_node) cur_val=width(tail);@+break; - case glue_val: if (type(tail)==glue_node) - {@+cur_val=glue_ptr(tail); - if (subtype(tail)==mu_glue) cur_val_level=mu_val; - } - } /*there are no other cases*/ - else if ((mode==vmode)&&(tail==head)) - switch (cur_chr) { - case int_val: cur_val=last_penalty;@+break; - case dimen_val: cur_val=last_kern;@+break; - case glue_val: if (last_glue!=max_halfword) cur_val=last_glue;@+break; - case last_node_type_code: cur_val=last_node_type; - } /*there are no other cases*/ - } - -@ @<Fetch a font dimension@>= -{@+find_font_dimen(false);font_info[fmem_ptr].sc=0; -scanned_result(font_info[cur_val].sc, dimen_val); -} - -@ @<Fetch a font integer@>= -{@+scan_font_ident(); -if (m==0) scanned_result(hyphen_char[cur_val], int_val)@; -else scanned_result(skew_char[cur_val], int_val); -} - -@ @<Fetch a register@>= -{@+if ((m < mem_bot)||(m > lo_mem_stat_max)) - {@+cur_val_level=sa_type(m); - if (cur_val_level < glue_val) cur_val=sa_int(m); - else cur_val=sa_ptr(m); - } -else{@+scan_register_num();cur_val_level=m-mem_bot; - if (cur_val > 255) - {@+find_sa_element(cur_val_level, cur_val, false); - if (cur_ptr==null) - if (cur_val_level < glue_val) cur_val=0; - else cur_val=zero_glue; - else if (cur_val_level < glue_val) cur_val=sa_int(cur_ptr); - else cur_val=sa_ptr(cur_ptr); - } - else - switch (cur_val_level) { -case int_val: cur_val=count(cur_val);@+break; -case dimen_val: - cur_hfactor=dimen_hfactor(cur_val); - cur_vfactor=dimen_vfactor(cur_val); - cur_val=dimen(cur_val);@+break; -case glue_val: cur_val=skip(cur_val);@+break; -case mu_val: cur_val=mu_skip(cur_val); -} /*there are no other cases*/ - } -} - -@ @<Complain that \.{\\the} can't do this; give zero result@>= -{@+print_err("You can't use `");print_cmd_chr(cur_cmd, cur_chr); -@.You can't use x after ...@> -print("' after ");print_esc("the"); -help1("I'm forgetting what you said and using zero instead."); -error(); -if (level!=tok_val) scanned_result(0, dimen_val)@; -else scanned_result(0, int_val); -} - -@ When a |glue_val| changes to a |dimen_val|, we use the width component -of the glue; there is no need to decrease the reference count, since it -has not yet been increased. When a |dimen_val| changes to an |int_val|, -we use scaled points so that the value doesn't actually change. And when a -|mu_val| changes to a |glue_val|, the value doesn't change either. - -@<Convert \(c)|cur_val| to a lower level@>= -{@+if (cur_val_level==glue_val) cur_val=width(cur_val); -else if (cur_val_level==mu_val) mu_error(); -decr(cur_val_level); -} - -@ If |cur_val| points to a glue specification at this point, the reference -count for the glue does not yet include the reference by |cur_val|. -If |negative| is |true|, |cur_val_level| is known to be | <= mu_val|. - -@<Fix the reference count, if any,...@>= -if (negative) - if (cur_val_level >= glue_val) - {@+cur_val=new_spec(cur_val); - @<Negate all three glue components of |cur_val|@>; - } - else {@+ negate(cur_val);@+ negate(cur_hfactor); @+negate(cur_vfactor); @+} -else if ((cur_val_level >= glue_val)&&(cur_val_level <= mu_val)) - add_glue_ref(cur_val) - -@ @<Negate all three...@>= -{@+negate(width(cur_val)); -negate(stretch(cur_val)); -negate(shrink(cur_val)); -} - -@ Our next goal is to write the |scan_int| procedure, which scans anything that -\TeX\ treats as an integer. But first we might as well look at some simple -applications of |scan_int| that have already been made inside of -|scan_something_internal|. - -@ @<Declare procedures that scan restricted classes of integers@>= -static void scan_eight_bit_int(void) -{@+scan_int(); -if ((cur_val < 0)||(cur_val > 255)) - {@+print_err("Bad register code"); -@.Bad register code@> - help2("A register number must be between 0 and 255.",@/ - "I changed this one to zero.");int_error(cur_val);cur_val=0; - } -} - -@ @<Declare procedures that scan restricted classes of integers@>= -static void scan_char_num(void) -{@+scan_int(); -if ((cur_val < 0)||(cur_val > 255)) - {@+print_err("Bad character code"); -@.Bad character code@> - help2("A character number must be between 0 and 255.",@/ - "I changed this one to zero.");int_error(cur_val);cur_val=0; - } -} - -@ While we're at it, we might as well deal with similar routines that -will be needed later. - -@<Declare procedures that scan restricted classes of integers@>= -static void scan_four_bit_int(void) -{@+scan_int(); -if ((cur_val < 0)||(cur_val > 15)) - {@+print_err("Bad number"); -@.Bad number@> - help2("Since I expected to read a number between 0 and 15,",@/ - "I changed this one to zero.");int_error(cur_val);cur_val=0; - } -} - -@ @<Declare procedures that scan restricted classes of integers@>= -static void scan_fifteen_bit_int(void) -{@+scan_int(); -if ((cur_val < 0)||(cur_val > 077777)) - {@+print_err("Bad mathchar"); -@.Bad mathchar@> - help2("A mathchar number must be between 0 and 32767.",@/ - "I changed this one to zero.");int_error(cur_val);cur_val=0; - } -} - -@ @<Declare procedures that scan restricted classes of integers@>= -static void scan_twenty_seven_bit_int(void) -{@+scan_int(); -if ((cur_val < 0)||(cur_val > 0777777777)) - {@+print_err("Bad delimiter code"); -@.Bad delimiter code@> - help2("A numeric delimiter code must be between 0 and 2^{27}-1.",@/ - "I changed this one to zero.");int_error(cur_val);cur_val=0; - } -} - -@ An integer number can be preceded by any number of spaces and `\.+' or -`\.-' signs. Then comes either a decimal constant (i.e., radix 10), an -octal constant (i.e., radix 8, preceded by~\.\'), a hexadecimal constant -(radix 16, preceded by~\."), an alphabetic constant (preceded by~\.\`), or -an internal variable. After scanning is complete, -|cur_val| will contain the answer, which must be at most -$2^{31}-1=2147483647$ in absolute value. The value of |radix| is set to -10, 8, or 16 in the cases of decimal, octal, or hexadecimal constants, -otherwise |radix| is set to zero. An optional space follows a constant. - -@d octal_token (other_token+'\'') /*apostrophe, indicates an octal constant*/ -@d hex_token (other_token+'"') /*double quote, indicates a hex constant*/ -@d alpha_token (other_token+'`') /*reverse apostrophe, precedes alpha constants*/ -@d point_token (other_token+'.') /*decimal point*/ -@d continental_point_token (other_token+',') /*decimal point, Eurostyle*/ - -@<Glob...@>= -static small_number @!radix; /*|scan_int| sets this to 8, 10, 16, or zero*/ - -@ We initialize the following global variables just in case |expand| -comes into action before any of the basic scanning routines has assigned -them a value. - -@<Set init...@>= -cur_val=0;cur_val_level=int_val;radix=0;cur_order=normal; - -@ The |scan_int| routine is used also to scan the integer part of a -fraction; for example, the `\.3' in `\.{3.14159}' will be found by -|scan_int|. The |scan_dimen| routine assumes that |cur_tok==point_token| -after the integer part of such a fraction has been scanned by |scan_int|, -and that the decimal point has been backed up to be scanned again. - -@p static void scan_int(void) /*sets |cur_val| to an integer*/ -{@+ -bool negative; /*should the answer be negated?*/ -int @!m; /*|@t$2^{31}$@>/radix|, the threshold of danger*/ -small_number @!d; /*the digit just scanned*/ -bool @!vacuous; /*have no digits appeared?*/ -bool @!OK_so_far; /*has an error message been issued?*/ -radix=0;OK_so_far=true;@/ -@<Get the next non-blank non-sign token; set |negative| appropriately@>; -if (cur_tok==alpha_token) @<Scan an alphabetic character code into |cur_val|@>@; -else if ((cur_cmd >= min_internal)&&(cur_cmd <= max_internal)) - scan_something_internal(int_val, false); -else@<Scan a numeric constant@>; -if (negative) negate(cur_val); -} - -@ @<Get the next non-blank non-sign token...@>= -negative=false; -@/do@+{@<Get the next non-blank non-call token@>; -if (cur_tok==other_token+'-') - {@+negative=!negative;cur_tok=other_token+'+'; - } -}@+ while (!(cur_tok!=other_token+'+')) - -@ A space is ignored after an alphabetic character constant, so that -such constants behave like numeric ones. - -@<Scan an alphabetic character code into |cur_val|@>= -{@+get_token(); /*suppress macro expansion*/ -if (cur_tok < cs_token_flag) - {@+cur_val=cur_chr; - if (cur_cmd <= right_brace) - if (cur_cmd==right_brace) incr(align_state); - else decr(align_state); - } -else if (cur_tok < cs_token_flag+single_base) - cur_val=cur_tok-cs_token_flag-active_base; -else cur_val=cur_tok-cs_token_flag-single_base; -if (cur_val > 255) - {@+print_err("Improper alphabetic constant"); -@.Improper alphabetic constant@> - help2("A one-character control sequence belongs after a ` mark.",@/ - "So I'm essentially inserting \\0 here."); - cur_val='0';back_error(); - } -else@<Scan an optional space@>; -} - -@ @<Scan an optional space@>= -{@+get_x_token();if (cur_cmd!=spacer) back_input(); -} - -@ @<Scan a numeric constant@>= -{@+radix=10;m=214748364; -if (cur_tok==octal_token) - {@+radix=8;m=02000000000;get_x_token(); - } -else if (cur_tok==hex_token) - {@+radix=16;m=01000000000;get_x_token(); - } -vacuous=true;cur_val=0;@/ -@<Accumulate the constant until |cur_tok| is not a suitable digit@>; -if (vacuous) @<Express astonishment that no number was here@>@; -else if (cur_cmd!=spacer) back_input(); -} - -@ @d infinity 017777777777 /*the largest positive value that \TeX\ knows*/ -@d zero_token (other_token+'0') /*zero, the smallest digit*/ -@d A_token (letter_token+'A') /*the smallest special hex digit*/ -@d other_A_token (other_token+'A') /*special hex digit of type |other_char|*/ - -@<Accumulate the constant...@>= -loop@+{@+if ((cur_tok < zero_token+radix)&&(cur_tok >= zero_token)&& - (cur_tok <= zero_token+9)) d=cur_tok-zero_token; - else if (radix==16) - if ((cur_tok <= A_token+5)&&(cur_tok >= A_token)) d=cur_tok-A_token+10; - else if ((cur_tok <= other_A_token+5)&&(cur_tok >= other_A_token)) - d=cur_tok-other_A_token+10; - else goto done; - else goto done; - vacuous=false; - if ((cur_val >= m)&&((cur_val > m)||(d > 7)||(radix!=10))) - {@+if (OK_so_far) - {@+print_err("Number too big"); -@.Number too big@> - help2("I can only go up to 2147483647='17777777777=\"7FFFFFFF,",@/ - "so I'm using that number instead of yours."); - error();cur_val=infinity;OK_so_far=false; - } - } - else cur_val=cur_val*radix+d; - get_x_token(); - } -done: - -@ @<Express astonishment...@>= -{@+print_err("Missing number, treated as zero"); -@.Missing number...@> -help3("A number should have been here; I inserted `0'.",@/ - "(If you can't figure out why I needed to see a number,",@/ - "look up `weird error' in the index to The TeXbook.)"); -@:TeXbook}{\sl The \TeX book@> -back_error(); -} - -@ The |scan_dimen| routine is similar to |scan_int|, but it sets |cur_val| to -a |scaled| value, i.e., an integral number of sp. One of its main tasks -is therefore to interpret the abbreviations for various kinds of units and -to convert measurements to scaled points. - -There are three parameters: |mu| is |true| if the finite units must be -`\.{mu}', while |mu| is |false| if `\.{mu}' units are disallowed; -|inf| is |true| if the infinite units `\.{fil}', `\.{fill}', `\.{filll}' -are permitted; and |shortcut| is |true| if |cur_val| already contains -an integer and only the units need to be considered. - -The order of infinity that was found in the case of infinite glue is returned -in the global variable |cur_order|. - -@<Glob...@>= -static glue_ord @!cur_order; /*order of infinity found by |scan_dimen|*/ - -@ Constructions like `\.{-\'77 pt}' are legal dimensions, so |scan_dimen| -may begin with |scan_int|. This explains why it is convenient to use -|scan_int| also for the integer part of a decimal fraction. - -Several branches of |scan_dimen| work with |cur_val| as an integer and -with an auxiliary fraction |f|, so that the actual quantity of interest is -$|cur_val|+|f|/2^{16}$. At the end of the routine, this ``unpacked'' -representation is put into the single word |cur_val|, which suddenly -switches significance from |int| to |scaled|. - -@d scan_normal_dimen scan_dimen(false, false, false) - -@p static void scan_dimen(bool @!mu, bool @!inf, bool @!shortcut) - /*sets |cur_val| to a dimension*/ -{@+ -bool negative; /*should the answer be negated?*/ -int @!f; /*numerator of a fraction whose denominator is $2^{16}$*/ -@<Local variables for dimension calculations@>@; -f=0;arith_error=false;cur_order=normal;negative=false; -cur_hfactor=cur_vfactor=0; -if (!shortcut) - {@+@<Get the next non-blank non-sign...@>; - if ((cur_cmd >= min_internal)&&(cur_cmd <= max_internal)) - @<Fetch an internal dimension and |goto attach_sign|, or fetch an internal integer@>@; - else{@+back_input(); - if (cur_tok==continental_point_token) cur_tok=point_token; - if (cur_tok!=point_token) scan_int(); - else{@+radix=10;cur_val=0; - } - if (cur_tok==continental_point_token) cur_tok=point_token; - if ((radix==10)&&(cur_tok==point_token)) @<Scan decimal fraction@>; - } - } -if (cur_val < 0) /*in this case |f==0|*/ - {@+negative=!negative;negate(cur_val); - } -@<Scan units and set |cur_val| to $x\cdot(|cur_val|+f/2^{16})$, where there are |x| -sp per unit; |goto attach_sign| if the units are internal@>; -@<Scan an optional space@>; -attach_sign: -if (arith_error||(abs(cur_val) >= 010000000000)|| -(abs(cur_hfactor) >= 010000000000) || (abs(cur_vfactor) >= 010000000000)) - @<Report that this dimension is out of range@>; -if (negative) @/{@+ negate(cur_val);@+ negate(cur_hfactor); @+negate(cur_vfactor);@+ } -} - -@ @<Fetch an internal dimension and |goto attach_sign|...@>= -if (mu) - {@+scan_something_internal(mu_val, false); - @<Coerce glue to a dimension@>; - if (cur_val_level==mu_val) goto attach_sign; - if (cur_val_level!=int_val) mu_error(); - } -else{@+scan_something_internal(dimen_val, false); - if (cur_val_level==dimen_val) goto attach_sign; - } - -@ @<Local variables for dimension calculations@>= -int @!num, @!denom; /*conversion ratio for the scanned units*/ -int @!k, @!kk; /*number of digits in a decimal fraction*/ -pointer @!p, @!q; /*top of decimal digit stack*/ -scaled @!v; /*an internal dimension*/ -int @!save_cur_val; /*temporary storage of |cur_val|*/ - -@ The following code is executed when |scan_something_internal| was -called asking for |mu_val|, when we really wanted a ``mudimen'' instead -of ``muglue.'' - -@<Coerce glue to a dimension@>= -if (cur_val_level >= glue_val) - {@+v=width(cur_val);delete_glue_ref(cur_val);cur_val=v; - } - -@ When the following code is executed, we have |cur_tok==point_token|, but this -token has been backed up using |back_input|; we must first discard it. - -It turns out that a decimal point all by itself is equivalent to `\.{0.0}'. -Let's hope people don't use that fact. - -@<Scan decimal fraction@>= -{@+k=0;p=null;get_token(); /*|point_token| is being re-scanned*/ -loop@+{@+get_x_token(); - if ((cur_tok > zero_token+9)||(cur_tok < zero_token)) goto done1; - if (k < 17) /*digits for |k >= 17| cannot affect the result*/ - {@+q=get_avail();link(q)=p;info(q)=cur_tok-zero_token; - p=q;incr(k); - } - } -done1: for (kk=k; kk>=1; kk--) - {@+dig[kk-1]=info(p);q=p;p=link(p);free_avail(q); - } -f=round_decimals(k); -if (cur_cmd!=spacer) back_input(); -} - -@ Now comes the harder part: At this point in the program, |cur_val| is a -nonnegative integer and $f/2^{16}$ is a nonnegative fraction less than 1; -we want to multiply the sum of these two quantities by the appropriate -factor, based on the specified units, in order to produce a |scaled| -result, and we want to do the calculation with fixed point arithmetic that -does not overflow. - -@<Scan units and set |cur_val| to $x\cdot(|cur_val|+f/2^{16})$...@>= -if (inf) @<Scan for \(f)\.{fil} units; |goto attach_fraction| if found@>; -@<Scan for \(u)units that are internal dimensions; |goto attach_sign| with |cur_val| -set if found@>; -if (mu) @<Scan for \(m)\.{mu} units and |goto attach_fraction|@>; -if (scan_keyword("true")) @<Adjust \(f)for the magnification ratio@>; -@.true@> -if (scan_keyword("pt")) goto attach_fraction; /*the easy case*/ -@.pt@> -@<Scan for \(a)all other units and adjust |cur_val| and |f| accordingly; |goto done| -in the case of scaled points@>; -attach_fraction: if (cur_val >= 040000) arith_error=true; -else cur_val=cur_val*unity+f; -done: - -@ A specification like `\.{filllll}' or `\.{fill L L L}' will lead to two -error messages (one for each additional keyword \.{"l"}). - -@<Scan for \(f)\.{fil} units...@>= -if (scan_keyword("fil")) -@.fil@> - {@+cur_order=fil; - while (scan_keyword("l")) - {@+if (cur_order==filll) - {@+print_err("Illegal unit of measure ("); -@.Illegal unit of measure@> - print("replaced by filll)"); - help1("I dddon't go any higher than filll.");error(); - } - else incr(cur_order); - } - goto attach_fraction; - } - -@ @<Scan for \(u)units that are internal dimensions...@>= -save_cur_val=cur_val; -if (has_factor) -{ print_err("Factor is not constant. Linear component ignored"); - cur_hfactor=cur_vfactor=0; -} -@<Get the next non-blank non-call...@>; -if ((cur_cmd < min_internal)||(cur_cmd > max_internal)) back_input(); -else{@+if (mu) - {@+scan_something_internal(mu_val, false);@<Coerce glue...@>; - if (cur_val_level!=mu_val) mu_error(); - } - else scan_something_internal(dimen_val, false); - v=cur_val;goto found; - } -if (mu) goto not_found; -if (scan_keyword("em")) v=(@<The em width for |cur_font|@>); -@.em@> -else if (scan_keyword("ex")) v=(@<The x-height for |cur_font|@>); -@.ex@> -else goto not_found; -@<Scan an optional space@>; -found: -if (has_factor) -{ cur_hfactor=nx_plus_y(save_cur_val, cur_hfactor, xn_over_d(cur_hfactor, f, unity)); - cur_vfactor=nx_plus_y(save_cur_val, cur_vfactor, xn_over_d(cur_vfactor, f, unity)); -} - cur_val=nx_plus_y(save_cur_val, v, xn_over_d(v, f, unity)); -goto attach_sign; -not_found: - -@ @<Scan for \(m)\.{mu} units and |goto attach_fraction|@>= -if (scan_keyword("mu")) goto attach_fraction; -@.mu@> -else{@+print_err("Illegal unit of measure (");print("mu inserted)"); -@.Illegal unit of measure@> - help4("The unit of measurement in math glue must be mu.",@/ - "To recover gracefully from this error, it's best to",@/ - "delete the erroneous units; e.g., type `2' to delete",@/ - "two letters. (See Chapter 27 of The TeXbook.)"); -@:TeXbook}{\sl The \TeX book@> - error();goto attach_fraction; - } - -@ @<Adjust \(f)for the magnification ratio@>= -{@+prepare_mag(); -if (mag!=1000) - {@+cur_val=xn_over_d(cur_val, 1000, mag); - f=(1000*f+0200000*rem)/mag; - cur_val=cur_val+(f/0200000);f=f%0200000; - } -} - -@ The necessary conversion factors can all be specified exactly as -fractions whose numerator and denominator sum to 32768 or less. -According to the definitions here, $\rm2660\,dd\approx1000.33297\,mm$; -this agrees well with the value $\rm1000.333\,mm$ cited by Bosshard -@^Bosshard, Hans Rudolf@> -in {\sl Technische Grundlagen zur Satzherstellung\/} (Bern, 1980). - -@d set_conversion(A, B) @+{@+num=A;denom=B;} - -@<Scan for \(a)all other units and adjust |cur_val| and |f|...@>= -if (scan_keyword("in")) set_conversion(7227, 100)@; -@.in@> -else if (scan_keyword("pc")) set_conversion(12, 1)@; -@.pc@> -else if (scan_keyword("cm")) set_conversion(7227, 254)@; -@.cm@> -else if (scan_keyword("mm")) set_conversion(7227, 2540)@; -@.mm@> -else if (scan_keyword("bp")) set_conversion(7227, 7200)@; -@.bp@> -else if (scan_keyword("dd")) set_conversion(1238, 1157)@; -@.dd@> -else if (scan_keyword("cc")) set_conversion(14856, 1157)@; -@.cc@> -else if (scan_keyword("sp")) goto done; -@.sp@> -else@<Complain about unknown unit and |goto done2|@>; -cur_val=xn_over_d(cur_val, num, denom); -f=(num*f+0200000*rem)/denom;@/ -cur_val=cur_val+(f/0200000);f=f%0200000; -done2: - -@ @<Complain about unknown unit...@>= -{@+print_err("Illegal unit of measure (");print("pt inserted)"); -@.Illegal unit of measure@> -help6("Dimensions can be in units of em, ex, in, pt, pc,",@/ - "cm, mm, dd, cc, bp, or sp; but yours is a new one!",@/ - "I'll assume that you meant to say pt, for printer's points.",@/ - "To recover gracefully from this error, it's best to",@/ - "delete the erroneous units; e.g., type `2' to delete",@/ - "two letters. (See Chapter 27 of The TeXbook.)"); -@:TeXbook}{\sl The \TeX book@> -error();goto done2; -} - - -@ @<Report that this dimension is out of range@>= -{@+print_err("Dimension too large"); -@.Dimension too large@> -help2("I can't work with sizes bigger than about 19 feet.",@/ - "Continue and I'll use the largest value I can.");@/ -error();cur_val=max_dimen;arith_error=false; -} - -@ The final member of \TeX's value-scanning trio is |scan_glue|, which -makes |cur_val| point to a glue specification. The reference count of that -glue spec will take account of the fact that |cur_val| is pointing to~it. - -The |level| parameter should be either |glue_val| or |mu_val|. - -Since |scan_dimen| was so much more complex than |scan_int|, we might expect -|scan_glue| to be even worse. But fortunately, it is very simple, since -most of the work has already been done. - -@p static void scan_glue(small_number @!level) - /*sets |cur_val| to a glue spec pointer*/ -{@+ -bool negative; /*should the answer be negated?*/ -pointer @!q; /*new glue specification*/ -bool @!mu; /*does |level==mu_val|?*/ -mu=(level==mu_val);@<Get the next non-blank non-sign...@>; -if ((cur_cmd >= min_internal)&&(cur_cmd <= max_internal)) - {@+scan_something_internal(level, negative); - if (cur_val_level >= glue_val) - {@+if (cur_val_level!=level) mu_error(); - return; - } - if (cur_val_level==int_val) scan_dimen(mu, false, true); - else if (level==mu_val) mu_error(); - } -else{@+back_input();scan_dimen(mu, false, false); - if (negative) { negate(cur_val); negate(cur_hfactor); negate(cur_vfactor);} - } -@<Create a new glue specification whose width is |cur_val|; scan for its stretch and -shrink components@>; -} -@# -@<Declare procedures needed for expressions@>@; - -@ @<Create a new glue specification whose width is |cur_val|...@>= -q=new_spec(zero_glue);width(q)=cur_val; -if (scan_keyword("plus")) -@.plus@> - {@+scan_dimen(mu, true, false); - stretch(q)=cur_val;stretch_order(q)=cur_order; - } -if (scan_keyword("minus")) -@.minus@> - {@+scan_dimen(mu, true, false); - shrink(q)=cur_val;shrink_order(q)=cur_order; - } -cur_val=q - -@ Here's a similar procedure that returns a pointer to a rule node. This -routine is called just after \TeX\ has seen \.{\\hrule} or \.{\\vrule}; -therefore |cur_cmd| will be either |hrule| or |vrule|. The idea is to store -the default rule dimensions in the node, then to override them if -`\.{height}' or `\.{width}' or `\.{depth}' specifications are -found (in any order). - -@d default_rule 26214 /*0.4\thinspace pt*/ - -@p static pointer scan_rule_spec(void) -{@+ -pointer q; /*the rule node being created*/ -q=new_rule(); /*|width|, |depth|, and |height| all equal |null_flag| now*/ -if (cur_cmd==vrule) width(q)=default_rule; -else{@+height(q)=default_rule;depth(q)=0; - } -reswitch: if (scan_keyword("width")) -@.width@> - {@+scan_normal_dimen;width(q)=cur_val;goto reswitch; - } -if (scan_keyword("height")) -@.height@> - {@+scan_normal_dimen;height(q)=cur_val;goto reswitch; - } -if (scan_keyword("depth")) -@.depth@> - {@+scan_normal_dimen;depth(q)=cur_val;goto reswitch; - } -return q; -} - -@* Building token lists. -The token lists for macros and for other things like \.{\\mark} and \.{\\output} -and \.{\\write} are produced by a procedure called |scan_toks|. - -Before we get into the details of |scan_toks|, let's consider a much -simpler task, that of converting the current string into a token list. -The |str_toks| function does this; it classifies spaces as type |spacer| -and everything else as type |other_char|. - -The token list created by |str_toks| begins at |link(temp_head)| and ends -at the value |p| that is returned. (If |p==temp_head|, the list is empty.) - -@p @t\4@>@<Declare \eTeX\ procedures for token lists@>@;@/ -static pointer str_toks(pool_pointer @!b) - /*converts |str_pool[b dotdot pool_ptr-1]| to a token list*/ -{@+pointer p; /*tail of the token list*/ -pointer @!q; /*new node being added to the token list via |store_new_token|*/ -halfword @!t; /*token being appended*/ -pool_pointer @!k; /*index into |str_pool|*/ -str_room(1); -p=temp_head;link(p)=null;k=b; -while (k < pool_ptr) - {@+t=so(str_pool[k]); - if (t==' ') t=space_token; - else t=other_token+t; - fast_store_new_token(t); - incr(k); - } -pool_ptr=b;return p; -} - -@ The main reason for wanting |str_toks| is the next function, -|the_toks|, which has similar input/output characteristics. - -This procedure is supposed to scan something like `\.{\\skip\\count12}', -i.e., whatever can follow `\.{\\the}', and it constructs a token list -containing something like `\.{-3.0pt minus 0.5fill}'. - -@p static pointer the_toks(void) -{@+ -int old_setting; /*holds |selector| setting*/ -pointer @!p, @!q, @!r; /*used for copying a token list*/ -pool_pointer @!b; /*base of temporary string*/ -small_number @!c; /*value of |cur_chr|*/ -@<Handle \.{\\unexpanded} or \.{\\detokenize} and |return|@>;@/ -get_x_token();scan_something_internal(tok_val, false); -if (cur_val_level >= ident_val) @<Copy the token list@>@; -else{@+old_setting=selector;selector=new_string;b=pool_ptr; - switch (cur_val_level) { - case int_val: print_int(cur_val);@+break; - case dimen_val: {@+print_scaled(cur_val);print("pt"); - } @+break; - case glue_val: {@+print_spec(cur_val,"pt");delete_glue_ref(cur_val); - } @+break; - case mu_val: {@+print_spec(cur_val,"mu");delete_glue_ref(cur_val); - } - } /*there are no other cases*/ - selector=old_setting;return str_toks(b); - } -} - -@ @<Copy the token list@>= -{@+p=temp_head;link(p)=null; -if (cur_val_level==ident_val) store_new_token(cs_token_flag+cur_val)@; -else if (cur_val!=null) - {@+r=link(cur_val); /*do not copy the reference count*/ - while (r!=null) - {@+fast_store_new_token(info(r));r=link(r); - } - } -return p; -} - -@ Here's part of the |expand| subroutine that we are now ready to complete: - -@p static void ins_the_toks(void) -{@+link(garbage)=the_toks();ins_list(link(temp_head)); -} - -@ The primitives \.{\\number}, \.{\\romannumeral}, \.{\\string}, \.{\\meaning}, -\.{\\fontname}, and \.{\\jobname} are defined as follows. - -\eTeX\ adds \.{\\eTeXrevision} such that |job_name_code| remains last. - -@d number_code 0 /*command code for \.{\\number}*/ -@d roman_numeral_code 1 /*command code for \.{\\romannumeral}*/ -@d string_code 2 /*command code for \.{\\string}*/ -@d meaning_code 3 /*command code for \.{\\meaning}*/ -@d font_name_code 4 /*command code for \.{\\fontname}*/ -@d etex_convert_base 5 /*base for \eTeX's command codes*/ -@d eTeX_revision_code etex_convert_base /*command code for \.{\\eTeXrevision}*/ -@d etex_convert_codes (etex_convert_base+1) /*end of \eTeX's command codes*/ -@d job_name_code etex_convert_codes /*command code for \.{\\jobname}*/ - -@<Put each...@>= -primitive("number", convert, number_code);@/ -@!@:number\_}{\.{\\number} primitive@> -primitive("romannumeral", convert, roman_numeral_code);@/ -@!@:roman\_numeral\_}{\.{\\romannumeral} primitive@> -primitive("string", convert, string_code);@/ -@!@:string\_}{\.{\\string} primitive@> -primitive("meaning", convert, meaning_code);@/ -@!@:meaning\_}{\.{\\meaning} primitive@> -primitive("fontname", convert, font_name_code);@/ -@!@:font\_name\_}{\.{\\fontname} primitive@> -primitive("jobname", convert, job_name_code);@/ -@!@:job\_name\_}{\.{\\jobname} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case convert: switch (chr_code) { - case number_code: print_esc("number");@+break; - case roman_numeral_code: print_esc("romannumeral");@+break; - case string_code: print_esc("string");@+break; - case meaning_code: print_esc("meaning");@+break; - case font_name_code: print_esc("fontname");@+break; - case eTeX_revision_code: print_esc("eTeXrevision");@+break; - default:print_esc("jobname"); - } @+break; - -@ The procedure |conv_toks| uses |str_toks| to insert the token list -for |convert| functions into the scanner; `\.{\\outer}' control sequences -are allowed to follow `\.{\\string}' and `\.{\\meaning}'. - -@p static void conv_toks(void) -{@+int old_setting; /*holds |selector| setting*/ -int @!c; /*desired type of conversion*/ -small_number @!save_scanner_status; /*|scanner_status| upon entry*/ -pool_pointer @!b; /*base of temporary string*/ -c=cur_chr;@<Scan the argument for command |c|@>; -old_setting=selector;selector=new_string;b=pool_ptr; -@<Print the result of command |c|@>; -selector=old_setting;link(garbage)=str_toks(b);ins_list(link(temp_head)); -} - -@ @<Scan the argument for command |c|@>= -switch (c) { -case number_code: case roman_numeral_code: scan_int();@+break; -case string_code: case meaning_code: {@+save_scanner_status=scanner_status; - scanner_status=normal;get_token();scanner_status=save_scanner_status; - } @+break; -case font_name_code: scan_font_ident();@+break; -case eTeX_revision_code: do_nothing;@+break; -case job_name_code: if (job_name==0) open_log_file(); -} /*there are no other cases*/ - -@ @<Print the result of command |c|@>= -switch (c) { -case number_code: print_int(cur_val);@+break; -case roman_numeral_code: print_roman_int(cur_val);@+break; -case string_code: if (cur_cs!=0) sprint_cs(cur_cs); - else print_char(cur_chr);@+break; -case meaning_code: print_meaning();@+break; -case font_name_code: {@+printn(font_name[cur_val]); - if (font_size[cur_val]!=font_dsize[cur_val]) - {@+print(" at ");print_scaled(font_size[cur_val]); - print("pt"); - } - } @+break; -case eTeX_revision_code: print(eTeX_revision);@+break; -case job_name_code: printn(job_name); -} /*there are no other cases*/ - -@ Now we can't postpone the difficulties any longer; we must bravely tackle -|scan_toks|. This function returns a pointer to the tail of a new token -list, and it also makes |def_ref| point to the reference count at the -head of that list. - -There are two boolean parameters, |macro_def| and |xpand|. If |macro_def| -is true, the goal is to create the token list for a macro definition; -otherwise the goal is to create the token list for some other \TeX\ -primitive: \.{\\mark}, \.{\\output}, \.{\\everypar}, \.{\\lowercase}, -\.{\\uppercase}, \.{\\message}, \.{\\errmessage}, \.{\\write}, or -\.{\\special}. In the latter cases a left brace must be scanned next; this -left brace will not be part of the token list, nor will the matching right -brace that comes at the end. If |xpand| is false, the token list will -simply be copied from the input using |get_token|. Otherwise all expandable -tokens will be expanded until unexpandable tokens are left, except that -the results of expanding `\.{\\the}' are not expanded further. -If both |macro_def| and |xpand| are true, the expansion applies -only to the macro body (i.e., to the material following the first -|left_brace| character). - -The value of |cur_cs| when |scan_toks| begins should be the |eqtb| -address of the control sequence to display in ``runaway'' error -messages. - -@p static pointer scan_toks(bool @!macro_def, bool @!xpand) -{@+ -halfword t; /*token representing the highest parameter number*/ -halfword @!s; /*saved token*/ -pointer @!p; /*tail of the token list being built*/ -pointer @!q; /*new node being added to the token list via |store_new_token|*/ -halfword @!unbalance; /*number of unmatched left braces*/ -halfword @!hash_brace; /*possible `\.{\#\{}' token*/ -if (macro_def) scanner_status=defining; -@+else scanner_status=absorbing; -warning_index=cur_cs;def_ref=get_avail();token_ref_count(def_ref)=null; -p=def_ref;hash_brace=0;t=zero_token; -if (macro_def) @<Scan and build the parameter part of the macro definition@>@; -else scan_left_brace(); /*remove the compulsory left brace*/ -@<Scan and build the body of the token list; |goto found| when finished@>; -found: scanner_status=normal; -if (hash_brace!=0) store_new_token(hash_brace); -return p; -} - -@ @<Scan and build the parameter part...@>= -{@+loop{@+resume: get_token(); /*set |cur_cmd|, |cur_chr|, |cur_tok|*/ - if (cur_tok < right_brace_limit) goto done1; - if (cur_cmd==mac_param) - @<If the next character is a parameter number, make |cur_tok| a |match| token; -but if it is a left brace, store `|left_brace|, |end_match|', set |hash_brace|, and -|goto done|@>; - store_new_token(cur_tok); - } -done1: store_new_token(end_match_token); -if (cur_cmd==right_brace) - @<Express shock at the missing left brace; |goto found|@>; -done: ;} - -@ @<Express shock...@>= -{@+print_err("Missing { inserted");incr(align_state); -@.Missing \{ inserted@> -help2("Where was the left brace? You said something like `\\def\\a}',",@/ - "which I'm going to interpret as `\\def\\a{}'.");error();goto found; -} - -@ @<If the next character is a parameter number...@>= -{@+s=match_token+cur_chr;get_token(); -if (cur_tok < left_brace_limit) - {@+hash_brace=cur_tok; - store_new_token(cur_tok);store_new_token(end_match_token); - goto done; - } -if (t==zero_token+9) - {@+print_err("You already have nine parameters"); -@.You already have nine...@> - help2("I'm going to ignore the # sign you just used,",@/ - "as well as the token that followed it.");error();goto resume; - } -else{@+incr(t); - if (cur_tok!=t) - {@+print_err("Parameters must be numbered consecutively"); -@.Parameters...consecutively@> - help2("I've inserted the digit you should have used after the #.",@/ - "Type `1' to delete what you did use.");back_error(); - } - cur_tok=s; - } -} - -@ @<Scan and build the body of the token list; |goto found| when finished@>= -unbalance=1; -loop@+{@+if (xpand) @<Expand the next part of the input@>@; - else get_token(); - if (cur_tok < right_brace_limit) - if (cur_cmd < right_brace) incr(unbalance); - else{@+decr(unbalance); - if (unbalance==0) goto found; - } - else if (cur_cmd==mac_param) - if (macro_def) @<Look for parameter number or \.{\#\#}@>; - store_new_token(cur_tok); - } - -@ Here we insert an entire token list created by |the_toks| without -expanding it further. - -@<Expand the next part of the input@>= -{@+loop{@+get_next(); - if (cur_cmd >= call) - if (info(link(cur_chr))==protected_token) - {@+cur_cmd=relax;cur_chr=no_expand_flag; - } - if (cur_cmd <= max_command) goto done2; - if (cur_cmd!=the) expand(); - else{@+q=the_toks(); - if (link(temp_head)!=null) - {@+link(p)=link(temp_head);p=q; - } - } - } -done2: x_token(); -} - -@ @<Look for parameter number...@>= -{@+s=cur_tok; -if (xpand) get_x_token();else get_token(); -if (cur_cmd!=mac_param) - if ((cur_tok <= zero_token)||(cur_tok > t)) - {@+print_err("Illegal parameter number in definition of "); -@.Illegal parameter number...@> - sprint_cs(warning_index); - help3("You meant to type ## instead of #, right?",@/ - "Or maybe a } was forgotten somewhere earlier, and things",@/ - "are all screwed up? I'm going to assume that you meant ##."); - back_error();cur_tok=s; - } - else cur_tok=out_param_token-'0'+cur_chr; -} - -@ Another way to create a token list is via the \.{\\read} command. The -sixteen files potentially usable for reading appear in the following -global variables. The value of |read_open[n]| will be |closed| if -stream number |n| has not been opened or if it has been fully read; -|just_open| if an \.{\\openin} but not a \.{\\read} has been done; -and |normal| if it is open and ready to read the next line. - -@d closed 2 /*not open, or at end of file*/ -@d just_open 1 /*newly opened, first line not yet read*/ - -@<Glob...@>= -static alpha_file @!read_file[16]; /*used for \.{\\read}*/ -static int8_t @!read_open[17]; /*state of |read_file[n]|*/ - -@ @<Set init...@>= -for (k=0; k<=16; k++) read_open[k]=closed; - -@ The |read_toks| procedure constructs a token list like that for any -macro definition, and makes |cur_val| point to it. Parameter |r| points -to the control sequence that will receive this token list. - -@p static void read_toks(int @!n, pointer @!r, halfword @!j) -{@+ -pointer p; /*tail of the token list*/ -pointer @!q; /*new node being added to the token list via |store_new_token|*/ -int @!s; /*saved value of |align_state|*/ -small_number @!m; /*stream number*/ -scanner_status=defining;warning_index=r; -def_ref=get_avail();token_ref_count(def_ref)=null; -p=def_ref; /*the reference count*/ -store_new_token(end_match_token); -if ((n < 0)||(n > 15)) m=16;@+else m=n; -s=align_state;align_state=1000000; /*disable tab marks, etc.*/ -@/do@+{@<Input and store tokens from the next line of the file@>; -}@+ while (!(align_state==1000000)); -cur_val=def_ref;scanner_status=normal;align_state=s; -} - -@ @<Input and store tokens from the next line of the file@>= -begin_file_reading();name=m+1; -if (read_open[m]==closed) @<Input for \.{\\read} from the terminal@>; -else if (read_open[m]==just_open) @<Input the first line of |read_file[m]|@>@; -else@<Input the next line of |read_file[m]|@>; -limit=last; -if (end_line_char_inactive) decr(limit); -else buffer[limit]=end_line_char; -first=limit+1;loc=start;state=new_line;@/ -@<Handle \.{\\readline} and |goto done|@>;@/ -loop@+{@+get_token(); - if (cur_tok==0) goto done; - /*|cur_cmd==cur_chr==0| will occur at the end of the line*/ - if (align_state < 1000000) /*unmatched `\.\}' aborts the line*/ - {@+@/do@+{get_token();}@+ while (!(cur_tok==0)); - align_state=1000000;goto done; - } - store_new_token(cur_tok); - } -done: end_file_reading() - -@ Here we input on-line into the |buffer| array, prompting the user explicitly -if |n >= 0|. The value of |n| is set negative so that additional prompts -will not be given in the case of multi-line input. - -@<Input for \.{\\read} from the terminal@>= -if (interaction > nonstop_mode) - if (n < 0) prompt_input("")@; - else{@+wake_up_terminal; - print_ln();sprint_cs(r);prompt_input("=");n=-1; - } -else fatal_error("*** (cannot \\read from terminal in nonstop modes)") -@.cannot \\read@> - -@ The first line of a file must be treated specially, since |input_ln| -must be told not to start with |get|. -@^system dependencies@> - -@<Input the first line of |read_file[m]|@>= -if (input_ln(&read_file[m], false)) read_open[m]=normal; -else{@+a_close(&read_file[m]);read_open[m]=closed; - } - -@ An empty line is appended at the end of a |read_file|. -@^empty line at end of file@> - -@<Input the next line of |read_file[m]|@>= -{@+if (!input_ln(&read_file[m], true)) - {@+a_close(&read_file[m]);read_open[m]=closed; - if (align_state!=1000000) - {@+runaway(); - print_err("File ended within ");print_esc("read"); -@.File ended within \\read@> - help1("This \\read has unbalanced braces."); - align_state=1000000;limit=0;error(); - } - } -} - -@* Conditional processing. -We consider now the way \TeX\ handles various kinds of \.{\\if} commands. - -@d unless_code 32 /*amount added for `\.{\\unless}' prefix*/ -@# -@d if_char_code 0 /* `\.{\\if}' */ -@d if_cat_code 1 /* `\.{\\ifcat}' */ -@d if_int_code 2 /* `\.{\\ifnum}' */ -@d if_dim_code 3 /* `\.{\\ifdim}' */ -@d if_odd_code 4 /* `\.{\\ifodd}' */ -@d if_vmode_code 5 /* `\.{\\ifvmode}' */ -@d if_hmode_code 6 /* `\.{\\ifhmode}' */ -@d if_mmode_code 7 /* `\.{\\ifmmode}' */ -@d if_inner_code 8 /* `\.{\\ifinner}' */ -@d if_void_code 9 /* `\.{\\ifvoid}' */ -@d if_hbox_code 10 /* `\.{\\ifhbox}' */ -@d if_vbox_code 11 /* `\.{\\ifvbox}' */ -@d ifx_code 12 /* `\.{\\ifx}' */ -@d if_eof_code 13 /* `\.{\\ifeof}' */ -@d if_true_code 14 /* `\.{\\iftrue}' */ -@d if_false_code 15 /* `\.{\\iffalse}' */ -@d if_case_code 16 /* `\.{\\ifcase}' */ - -@<Put each...@>= -primitive("if", if_test, if_char_code); -@!@:if\_char\_}{\.{\\if} primitive@> -primitive("ifcat", if_test, if_cat_code); -@!@:if\_cat\_code\_}{\.{\\ifcat} primitive@> -primitive("ifnum", if_test, if_int_code); -@!@:if\_int\_}{\.{\\ifnum} primitive@> -primitive("ifdim", if_test, if_dim_code); -@!@:if\_dim\_}{\.{\\ifdim} primitive@> -primitive("ifodd", if_test, if_odd_code); -@!@:if\_odd\_}{\.{\\ifodd} primitive@> -primitive("ifvmode", if_test, if_vmode_code); -@!@:if\_vmode\_}{\.{\\ifvmode} primitive@> -primitive("ifhmode", if_test, if_hmode_code); -@!@:if\_hmode\_}{\.{\\ifhmode} primitive@> -primitive("ifmmode", if_test, if_mmode_code); -@!@:if\_mmode\_}{\.{\\ifmmode} primitive@> -primitive("ifinner", if_test, if_inner_code); -@!@:if\_inner\_}{\.{\\ifinner} primitive@> -primitive("ifvoid", if_test, if_void_code); -@!@:if\_void\_}{\.{\\ifvoid} primitive@> -primitive("ifhbox", if_test, if_hbox_code); -@!@:if\_hbox\_}{\.{\\ifhbox} primitive@> -primitive("ifvbox", if_test, if_vbox_code); -@!@:if\_vbox\_}{\.{\\ifvbox} primitive@> -primitive("ifx", if_test, ifx_code); -@!@:ifx\_}{\.{\\ifx} primitive@> -primitive("ifeof", if_test, if_eof_code); -@!@:if\_eof\_}{\.{\\ifeof} primitive@> -primitive("iftrue", if_test, if_true_code); -@!@:if\_true\_}{\.{\\iftrue} primitive@> -primitive("iffalse", if_test, if_false_code); -@!@:if\_false\_}{\.{\\iffalse} primitive@> -primitive("ifcase", if_test, if_case_code); -@!@:if\_case\_}{\.{\\ifcase} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case if_test: {@+if (chr_code >= unless_code) print_esc("unless"); -switch (chr_code%unless_code) { - case if_cat_code: print_esc("ifcat");@+break; - case if_int_code: print_esc("ifnum");@+break; - case if_dim_code: print_esc("ifdim");@+break; - case if_odd_code: print_esc("ifodd");@+break; - case if_vmode_code: print_esc("ifvmode");@+break; - case if_hmode_code: print_esc("ifhmode");@+break; - case if_mmode_code: print_esc("ifmmode");@+break; - case if_inner_code: print_esc("ifinner");@+break; - case if_void_code: print_esc("ifvoid");@+break; - case if_hbox_code: print_esc("ifhbox");@+break; - case if_vbox_code: print_esc("ifvbox");@+break; - case ifx_code: print_esc("ifx");@+break; - case if_eof_code: print_esc("ifeof");@+break; - case if_true_code: print_esc("iftrue");@+break; - case if_false_code: print_esc("iffalse");@+break; - case if_case_code: print_esc("ifcase");@+break; - @/@<Cases of |if_test| for |print_cmd_chr|@>@/ - default:print_esc("if"); - } -} @+break; - -@ Conditions can be inside conditions, and this nesting has a stack -that is independent of the |save_stack|. - -Four global variables represent the top of the condition stack: -|cond_ptr| points to pushed-down entries, if any; |if_limit| specifies -the largest code of a |fi_or_else| command that is syntactically legal; -|cur_if| is the name of the current type of conditional; and |if_line| -is the line number at which it began. - -If no conditions are currently in progress, the condition stack has the -special state |cond_ptr==null|, |if_limit==normal|, |cur_if==0|, |if_line==0|. -Otherwise |cond_ptr| points to a two-word node; the |type|, |subtype|, and -|link| fields of the first word contain |if_limit|, |cur_if|, and -|cond_ptr| at the next level, and the second word contains the -corresponding |if_line|. - -@d if_node_size 2 /*number of words in stack entry for conditionals*/ -@d if_line_field(A) mem[A+1].i -@d if_code 1 /*code for \.{\\if...} being evaluated*/ -@d fi_code 2 /*code for \.{\\fi}*/ -@d else_code 3 /*code for \.{\\else}*/ -@d or_code 4 /*code for \.{\\or}*/ - -@<Glob...@>= -static pointer @!cond_ptr; /*top of the condition stack*/ -static int @!if_limit; /*upper bound on |fi_or_else| codes*/ -static small_number @!cur_if; /*type of conditional being worked on*/ -static int @!if_line; /*line where that conditional began*/ - -@ @<Set init...@>= -cond_ptr=null;if_limit=normal;cur_if=0;if_line=0; - -@ @<Put each...@>= -primitive("fi", fi_or_else, fi_code); -@!@:fi\_}{\.{\\fi} primitive@> -text(frozen_fi)=text(cur_val);eqtb[frozen_fi]=eqtb[cur_val]; -primitive("or", fi_or_else, or_code); -@!@:or\_}{\.{\\or} primitive@> -primitive("else", fi_or_else, else_code); -@!@:else\_}{\.{\\else} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case fi_or_else: if (chr_code==fi_code) print_esc("fi"); - else if (chr_code==or_code) print_esc("or"); - else print_esc("else");@+break; - -@ When we skip conditional text, we keep track of the line number -where skipping began, for use in error messages. - -@<Glob...@>= -static int @!skip_line; /*skipping began here*/ - -@ Here is a procedure that ignores text until coming to an \.{\\or}, -\.{\\else}, or \.{\\fi} at the current level of $\.{\\if}\ldots\.{\\fi}$ -nesting. After it has acted, |cur_chr| will indicate the token that -was found, but |cur_tok| will not be set (because this makes the -procedure run faster). - -@p static void pass_text(void) -{@+ -int l; /*level of $\.{\\if}\ldots\.{\\fi}$ nesting*/ -small_number @!save_scanner_status; /*|scanner_status| upon entry*/ -save_scanner_status=scanner_status;scanner_status=skipping;l=0; -skip_line=line; -loop@+{@+get_next(); - if (cur_cmd==fi_or_else) - {@+if (l==0) goto done; - if (cur_chr==fi_code) decr(l); - } - else if (cur_cmd==if_test) incr(l); - } -done: scanner_status=save_scanner_status; -if (tracing_ifs > 0) show_cur_cmd_chr(); -} - -@ When we begin to process a new \.{\\if}, we set |if_limit=if_code|; then -if\/ \.{\\or} or \.{\\else} or \.{\\fi} occurs before the current \.{\\if} -condition has been evaluated, \.{\\relax} will be inserted. -For example, a sequence of commands like `\.{\\ifvoid1\\else...\\fi}' -would otherwise require something after the `\.1'. - -@<Push the condition stack@>= -{@+p=get_node(if_node_size);link(p)=cond_ptr;type(p)=if_limit; -subtype(p)=cur_if;if_line_field(p)=if_line; -cond_ptr=p;cur_if=cur_chr;if_limit=if_code;if_line=line; -} - -@ @<Pop the condition stack@>= -{@+if (if_stack[in_open]==cond_ptr) if_warning(); - /*conditionals possibly not properly nested with files*/ -p=cond_ptr;if_line=if_line_field(p); -cur_if=subtype(p);if_limit=type(p);cond_ptr=link(p); -free_node(p, if_node_size); -} - -@ Here's a procedure that changes the |if_limit| code corresponding to -a given value of |cond_ptr|. - -@p static void change_if_limit(small_number @!l, pointer @!p) -{@+ -pointer q; -if (p==cond_ptr) if_limit=l; /*that's the easy case*/ -else{@+q=cond_ptr; - loop@+{@+if (q==null) confusion("if"); -@:this can't happen if}{\quad if@> - if (link(q)==p) - {@+type(q)=l;return; - } - q=link(q); - } - } -} - -@ A condition is started when the |expand| procedure encounters -an |if_test| command; in that case |expand| reduces to |conditional|, -which is a recursive procedure. -@^recursion@> - -@p static void conditional(void) -{@+ -bool b; /*is the condition true?*/ -int @!r; /*relation to be evaluated*/ -int @!m, @!n; /*to be tested against the second operand*/ -pointer @!p, @!q; /*for traversing token lists in \.{\\ifx} tests*/ -small_number @!save_scanner_status; /*|scanner_status| upon entry*/ -pointer @!save_cond_ptr; /*|cond_ptr| corresponding to this conditional*/ -small_number @!this_if; /*type of this conditional*/ -bool @!is_unless; /*was this if preceded by `\.{\\unless}' ?*/ -if (tracing_ifs > 0) if (tracing_commands <= 1) show_cur_cmd_chr(); -@<Push the condition stack@>;@+save_cond_ptr=cond_ptr; -is_unless=(cur_chr >= unless_code);this_if=cur_chr%unless_code;@/ -@<Either process \.{\\ifcase} or set |b| to the value of a boolean condition@>; -if (is_unless) b=!b; -if (tracing_commands > 1) @<Display the value of |b|@>; -if (b) - {@+change_if_limit(else_code, save_cond_ptr); - return; /*wait for \.{\\else} or \.{\\fi}*/ - } -@<Skip to \.{\\else} or \.{\\fi}, then |goto common_ending|@>; -common_ending: if (cur_chr==fi_code) @<Pop the condition stack@>@; -else if_limit=fi_code; /*wait for \.{\\fi}*/ -} - -@ In a construction like `\.{\\if\\iftrue abc\\else d\\fi}', the first -\.{\\else} that we come to after learning that the \.{\\if} is false is -not the \.{\\else} we're looking for. Hence the following curious -logic is needed. - -@ @<Skip to \.{\\else} or \.{\\fi}...@>= -loop@+{@+pass_text(); - if (cond_ptr==save_cond_ptr) - {@+if (cur_chr!=or_code) goto common_ending; - print_err("Extra ");print_esc("or"); -@.Extra \\or@> - help1("I'm ignoring this; it doesn't match any \\if."); - error(); - } - else if (cur_chr==fi_code) @<Pop the condition stack@>; - } - -@ @<Either process \.{\\ifcase} or set |b|...@>= -switch (this_if) { -case if_char_code: case if_cat_code: @<Test if two characters match@>@;@+break; -case if_int_code: case if_dim_code: @<Test relation between integers or dimensions@>@;@+break; -case if_odd_code: @<Test if an integer is odd@>@;@+break; -case if_vmode_code: b=(abs(mode)==vmode);@+break; -case if_hmode_code: b=(abs(mode)==hmode);@+break; -case if_mmode_code: b=(abs(mode)==mmode);@+break; -case if_inner_code: b=(mode < 0);@+break; -case if_void_code: case if_hbox_code: case if_vbox_code: @<Test box register status@>@;@+break; -case ifx_code: @<Test if two tokens match@>@;@+break; -case if_eof_code: {@+scan_four_bit_int();b=(read_open[cur_val]==closed); - } @+break; -case if_true_code: b=true;@+break; -case if_false_code: b=false;@+break; -@/@<Cases for |conditional|@>@/ -case if_case_code: @<Select the appropriate case and |return| or |goto common_ending|@>; -} /*there are no other cases*/ - -@ @<Display the value of |b|@>= -{@+begin_diagnostic(); -if (b) print("{true}");@+else print("{false}"); -end_diagnostic(false); -} - -@ Here we use the fact that |'<'|, |'='|, and |'>'| are consecutive ASCII -codes. -@^ASCII code@> - -@<Test relation between integers or dimensions@>= -{@+if (this_if==if_int_code) scan_int();@+else scan_normal_dimen; -n=cur_val;@<Get the next non-blank non-call...@>; -if ((cur_tok >= other_token+'<')&&(cur_tok <= other_token+'>')) - r=cur_tok-other_token; -else{@+print_err("Missing = inserted for "); -@.Missing = inserted@> - print_cmd_chr(if_test, this_if); - help1("I was expecting to see `<', `=', or `>'. Didn't."); - back_error();r='='; - } -if (this_if==if_int_code) scan_int();@+else scan_normal_dimen; -switch (r) { -case '<': b=(n < cur_val);@+break; -case '=': b=(n==cur_val);@+break; -case '>': b=(n > cur_val); -} -} - -@ @<Test if an integer is odd@>= -{@+scan_int();b=odd(cur_val); -} - -@ @<Test box register status@>= -{@+scan_register_num();fetch_box(p); -if (this_if==if_void_code) b=(p==null); -else if (p==null) b=false; -else if (this_if==if_hbox_code) b=(type(p)==hlist_node); -else b=(type(p)==vlist_node); -} - -@ An active character will be treated as category 13 following -\.{\\if\\noexpand} or following \.{\\ifcat\\noexpand}. We use the fact that -active characters have the smallest tokens, among all control sequences. - -@d get_x_token_or_active_char @t@>@; - {@+get_x_token(); - if (cur_cmd==relax) if (cur_chr==no_expand_flag) - {@+cur_cmd=active_char; - cur_chr=cur_tok-cs_token_flag-active_base; - } - } - -@<Test if two characters match@>= -{@+get_x_token_or_active_char; -if ((cur_cmd > active_char)||(cur_chr > 255)) /*not a character*/ - {@+m=relax;n=256; - } -else{@+m=cur_cmd;n=cur_chr; - } -get_x_token_or_active_char; -if ((cur_cmd > active_char)||(cur_chr > 255)) - {@+cur_cmd=relax;cur_chr=256; - } -if (this_if==if_char_code) b=(n==cur_chr);@+else b=(m==cur_cmd); -} - -@ Note that `\.{\\ifx}' will declare two macros different if one is \\{long} -or \\{outer} and the other isn't, even though the texts of the macros are -the same. - -We need to reset |scanner_status|, since \.{\\outer} control sequences -are allowed, but we might be scanning a macro definition or preamble. - -@<Test if two tokens match@>= -{@+save_scanner_status=scanner_status;scanner_status=normal; -get_next();n=cur_cs;p=cur_cmd;q=cur_chr; -get_next();if (cur_cmd!=p) b=false; -else if (cur_cmd < call) b=(cur_chr==q); -else@<Test if two macro texts match@>; -scanner_status=save_scanner_status; -} - -@ Note also that `\.{\\ifx}' decides that macros \.{\\a} and \.{\\b} are -different in examples like this: -$$\vbox{\halign{\.{#}\hfil&\qquad\.{#}\hfil\cr - {}\\def\\a\{\\c\}& - {}\\def\\c\{\}\cr - {}\\def\\b\{\\d\}& - {}\\def\\d\{\}\cr}}$$ - -@<Test if two macro texts match@>= -{@+p=link(cur_chr);q=link(equiv(n)); /*omit reference counts*/ -if (p==q) b=true; -else{@+while ((p!=null)&&(q!=null)) - if (info(p)!=info(q)) p=null; - else{@+p=link(p);q=link(q); - } - b=((p==null)&&(q==null)); - } -} - -@ @<Select the appropriate case and |return| or |goto common_ending|@>= -{@+scan_int();n=cur_val; /*|n| is the number of cases to pass*/ -if (tracing_commands > 1) - {@+begin_diagnostic();print("{case ");print_int(n);print_char('}'); - end_diagnostic(false); - } -while (n!=0) - {@+pass_text(); - if (cond_ptr==save_cond_ptr) - if (cur_chr==or_code) decr(n); - else goto common_ending; - else if (cur_chr==fi_code) @<Pop the condition stack@>; - } -change_if_limit(or_code, save_cond_ptr); -return; /*wait for \.{\\or}, \.{\\else}, or \.{\\fi}*/ -} - -@ The processing of conditionals is complete except for the following -code, which is actually part of |expand|. It comes into play when -\.{\\or}, \.{\\else}, or \.{\\fi} is scanned. - -@<Terminate the current conditional and skip to \.{\\fi}@>= -{@+if (tracing_ifs > 0) if (tracing_commands <= 1) show_cur_cmd_chr(); -if (cur_chr > if_limit) - if (if_limit==if_code) insert_relax(); /*condition not yet evaluated*/ - else{@+print_err("Extra ");print_cmd_chr(fi_or_else, cur_chr); -@.Extra \\or@> -@.Extra \\else@> -@.Extra \\fi@> - help1("I'm ignoring this; it doesn't match any \\if."); - error(); - } -else{@+while (cur_chr!=fi_code) pass_text(); /*skip to \.{\\fi}*/ - @<Pop the condition stack@>; - } -} - -@* File names. -It's time now to fret about file names. Besides the fact that different -operating systems treat files in different ways, we must cope with the -fact that completely different naming conventions are used by different -groups of people. The following programs show what is required for one -particular operating system; similar routines for other systems are not -difficult to devise. -@^fingers@> -@^system dependencies@> - -\TeX\ assumes that a file name has three parts: the name proper; its -``extension''; and a ``file area'' where it is found in an external file -system. The extension of an input file or a write file is assumed to be -`\.{.tex}' unless otherwise specified; it is `\.{.log}' on the -transcript file that records each run of \TeX; it is `\.{.tfm}' on the font -metric files that describe characters in the fonts \TeX\ uses; it is -`\.{.dvi}' on the output files that specify typesetting information; and it -is `\.{.fmt}' on the format files written by \.{INITEX} to initialize \TeX. -The file area can be arbitrary on input files, but files are usually -output to the user's current area. If an input file cannot be -found on the specified area, \TeX\ will look for it on a special system -area; this special area is intended for commonly used input files like -\.{webmac.tex}. - -Simple uses of \TeX\ refer only to file names that have no explicit -extension or area. For example, a person usually says `\.{\\input} \.{paper}' -or `\.{\\font\\tenrm} \.= \.{helvetica}' instead of `\.{\\input} -\.{paper.new}' or `\.{\\font\\tenrm} \.= \.{<csd.knuth>test}'. Simple file -names are best, because they make the \TeX\ source files portable; -whenever a file name consists entirely of letters and digits, it should be -treated in the same way by all implementations of \TeX. However, users -need the ability to refer to other files in their environment, especially -when responding to error messages concerning unopenable files; therefore -we want to let them use the syntax that appears in their favorite -operating system. - -The following procedures don't allow spaces to be part of -file names; but some users seem to like names that are spaced-out. -System-dependent changes to allow such things should probably -be made with reluctance, and only when an entire file name that -includes spaces is ``quoted'' somehow. - -@ In order to isolate the system-dependent aspects of file names, the -@^system dependencies@> -system-independent parts of \TeX\ are expressed in terms -of three system-dependent -procedures called |begin_name|, |more_name|, and |end_name|. In -essence, if the user-specified characters of the file name are $c_1\ldots c_n$, -the system-independent driver program does the operations -$$|begin_name|;\,|more_name|(c_1);\,\ldots\,;\,|more_name|(c_n); -\,|end_name|.$$ -These three procedures communicate with each other via global variables. -Afterwards the file name will appear in the string pool as three strings -called |cur_name|\penalty10000\hskip-.05em, -|cur_area|, and |cur_ext|; the latter two are null (i.e., -|""|), unless they were explicitly specified by the user. - -Actually the situation is slightly more complicated, because \TeX\ needs -to know when the file name ends. The |more_name| routine is a function -(with side effects) that returns |true| on the calls |more_name|$(c_1)$, -\dots, |more_name|$(c_{n-1})$. The final call |more_name|$(c_n)$ -returns |false|; or, it returns |true| and the token following $c_n$ is -something like `\.{\\hbox}' (i.e., not a character). In other words, -|more_name| is supposed to return |true| unless it is sure that the -file name has been completely scanned; and |end_name| is supposed to be able -to finish the assembly of |cur_name|, |cur_area|, and |cur_ext| regardless of -whether $|more_name|(c_n)$ returned |true| or |false|. - -@<Glob...@>= -static str_number @!cur_name; /*name of file just scanned*/ -static char *@!cur_area; /*file area just scanned, or \.{""}*/ -static char *@!cur_ext; /*file extension just scanned, or \.{""}*/ - -@ The file names we shall deal with for illustrative purposes have the -following structure: If the name contains `\.>' or `\.:', the file area -consists of all characters up to and including the final such character; -otherwise the file area is null. If the remaining file name contains -`\..', the file extension consists of all such characters from the first -remaining `\..' to the end, otherwise the file extension is null. -@^system dependencies@> - -We can scan such file names easily by using two global variables that keep track -of the occurrences of area and extension delimiters: - -@<Glob...@>= -static pool_pointer @!area_delimiter; /*the most recent `\.>' or `\.:', if any*/ -static pool_pointer @!ext_delimiter; /*the relevant `\..', if any*/ -static int @!cur_file_name_length; - -@ Input files that can't be found in the user's area may appear in a standard -system area called |TEX_area|. Font metric files whose areas are not given -explicitly are assumed to appear in a standard system area called -|TEX_font_area|. These system area names will, of course, vary from place -to place. -@^system dependencies@> - -@d TEX_area "TeXinputs/" -@.TeXinputs@> -@d TEX_font_area "TeXfonts/" -@.TeXfonts@> - -@ Here now is the first of the system-dependent routines for file name scanning. -@^system dependencies@> - -The filename is scanned into |cur_file_name|; |cur_ext| and |cur_aire| -will point into this buffer. - -@d MAX_CUR_FILE_NAME 1024 - -@p static char cur_file_name[MAX_CUR_FILE_NAME+1]; -static void begin_name(void) -{@+area_delimiter=ext_delimiter=cur_file_name_length=0; -} - -@ And here's the second. The string pool might change as the file name is -being scanned, since a new \.{\\csname} might be entered; therefore we keep -|area_delimiter| and |ext_delimiter| relative to the beginning of the current -string, instead of assigning an absolute address like |pool_ptr| to them. -@^system dependencies@> - -@p static bool more_name(ASCII_code @!c) -{@+if (c==' ') return false; - if (cur_file_name_length>= MAX_CUR_FILE_NAME ) - { overflow("file name length", MAX_CUR_FILE_NAME); - return false; - } - else - { /*contribute |c| to the current string*/ - cur_file_name[cur_file_name_length]=c; - if (c=='/') - {@+area_delimiter=cur_file_name_length;ext_delimiter=0; - } - else if (c=='.') ext_delimiter=cur_file_name_length; - cur_file_name_length++; - return true; - } -} - -@ The third. -@^system dependencies@> - -@p static void end_name(void) -{@+int i=0; - if (str_ptr+1 > max_strings) - overflow("number of strings", max_strings-init_str_ptr); -@:TeX capacity exceeded number of strings}{\quad number of strings@> -cur_file_name[cur_file_name_length]=0; -if (area_delimiter==0) cur_area=cur_file_name+cur_file_name_length; -else @+cur_area=cur_file_name,i=area_delimiter+1; -if (ext_delimiter==0) ext_delimiter=cur_file_name_length; -cur_ext=cur_file_name+ext_delimiter; -for (;i<ext_delimiter;i++) append_char(cur_file_name[i]); -if (area_delimiter!=0) cur_file_name[area_delimiter+1]=0; -cur_name=make_string(); -} - -static void set_cur_area_ext(str_number a, str_number e) -{ int i; - if (length(a)+length(e)+2>=MAX_CUR_FILE_NAME) - { overflow("file name length", MAX_CUR_FILE_NAME); - return; - } - cur_file_name_length=0; - area_delimiter=0; - for(i=str_start[a]; i<str_start[a+1];i++) cur_file_name[cur_file_name_length++]=str_pool[i]; - cur_file_name[cur_file_name_length++]=0; - cur_area=cur_file_name; - cur_ext=cur_file_name+cur_file_name_length; - for(i=str_start[e]; i<str_start[e+1];i++) cur_file_name[cur_file_name_length++]=str_pool[i]; - cur_file_name[cur_file_name_length++]=0; -} - -@ Conversely, here is a routine that takes three strings and prints a file -name that might have produced them. (The routine is system dependent, because -some operating systems put the file area last instead of first.) -@^system dependencies@> - -@<Basic printing...@>= -static void print_file_name(int @!n, char *@!a, char *@!e) -{@+print(a);slow_print(n);print(e); -} - -static void printn_file_name(int @!n, int @!a, int @!e) -{@+slow_print(a);slow_print(n);slow_print(e); -} - -@ Another system-dependent routine is needed to convert three internal -\TeX\ strings -into the |name_of_file| value that is used to open files. The present code -allows both lowercase and uppercase letters in the file name. -@^system dependencies@> - -@d append_to_name(A) {@+c=A;incr(k); - if (k <= file_name_size) name_of_file[k]=xchr[c]; - } - -@p void pack_file_name(str_number @!n, char *@!a, char *@!e) -{@+int k; /*number of positions filled in |name_of_file|*/ -ASCII_code @!c; /*character being packed*/ -int @!j; /*index into |str_pool|*/ -k=0; -while(*a!=0) append_to_name(so(*a++)); -for (j=str_start[n]; j<=str_start[n+1]-1; j++) append_to_name(so(str_pool[j])); -while(*e!=0) append_to_name(so(*e++)); -if (k <= file_name_size) name_length=k;@+else name_length=file_name_size; -name_of_file[name_length+1]=0; -} - - -@ The global variable |TEX_format_default| is no longer needed -to supply the text for default system areas -and extensions related to format files. - -@ Consequently there is no initialization of |TEX_format_default| either. - -@ And there is no need to check the length of |TEX_format_default|. - -@ The |format_extension|, however, is needed later on -to create the format name from the job name. - -@d format_extension ".fmt" - -@ This part of the program -becomes active when a ``virgin'' \TeX\ is trying to get going, just after -the preliminary initialization, or when the user is substituting another -format file by typing `\.\&' after the initial `\.{**}' prompt. The buffer -contains the first line of input in |buffer[loc dotdot(last-1)]|, where -|loc < last| and |buffer[loc]!=' '|. - -k\TeX\ uses the {\tt kpathsearch} library to implement access to files. -To do so we declare |open_fmt_file| here and postpone the -actual implementation. - -@<Declare the function called |open_fmt_file|@>= -static bool open_fmt_file(void); - -@ Operating systems often make it possible to determine the exact name (and -possible version number) of a file that has been opened. The following routine, -which simply makes a \TeX\ string from the value of |name_of_file|, should -ideally be changed to deduce the full name of file~|f|, which is the file -most recently opened, if it is possible to do this in a \PASCAL\ program. -@^system dependencies@> - -This routine might be called after string memory has overflowed, hence -we dare not use `|str_room|'. - -@p static str_number make_name_string(void) -{@+int k; /*index into |name_of_file|*/ -if ((pool_ptr+name_length > pool_size)||(str_ptr==max_strings)|| - (cur_length > 0)) - return'?'; -else{@+for (k=1; k<=name_length; k++) append_char(xord[name_of_file[k]]); - return make_string(); - } -} -static str_number a_make_name_string(alpha_file *f) -{@+return make_name_string(); -} -static str_number b_make_name_string(byte_file *f) -{@+return make_name_string(); -} -#ifdef @!INIT -static str_number w_make_name_string(word_file *f) -{@+return make_name_string(); -} -#endif - -@ Now let's consider the ``driver'' -routines by which \TeX\ deals with file names -in a system-independent manner. First comes a procedure that looks for a -file name in the input by calling |get_x_token| for the information. - -@p static void scan_file_name(void) -{@+ -name_in_progress=true;begin_name(); -@<Get the next non-blank non-call...@>; -loop@+{@+if ((cur_cmd > other_char)||(cur_chr > 255)) /*not a character*/ - {@+back_input();goto done; - } - if (!more_name(cur_chr)) goto done; - get_x_token(); - } -done: end_name();name_in_progress=false; -} - -@ The global variable |name_in_progress| is used to prevent recursive -use of |scan_file_name|, since the |begin_name| and other procedures -communicate via global variables. Recursion would arise only by -devious tricks like `\.{\\input\\input f}'; such attempts at sabotage -must be thwarted. Furthermore, |name_in_progress| prevents \.{\\input} -@^recursion@> -from being initiated when a font size specification is being scanned. - -Another global variable, |job_name|, contains the file name that was first -\.{\\input} by the user. This name is extended by `\.{.log}' and `\.{.dvi}' -and `\.{.fmt}' in the names of \TeX's output files. - -@<Glob...@>= -static bool @!name_in_progress; /*is a file name being scanned?*/ -str_number @!job_name; /*principal file name*/ -static bool @!log_opened; /*has the transcript file been opened?*/ - -@ Initially |job_name==0|; it becomes nonzero as soon as the true name is known. -We have |job_name==0| if and only if the `\.{log}' file has not been opened, -except of course for a short time just after |job_name| has become nonzero. - -@<Initialize the output...@>= -job_name=0;name_in_progress=false;log_opened=false; - -@ Here is a routine that manufactures the output file names, assuming that -|job_name!=0|. It ignores and changes the current settings of |cur_area| -and |cur_ext|. - -@d pack_cur_name pack_file_name(cur_name, cur_area, cur_ext) - -@p void pack_job_name(char *@!s) /*|s==".log"|, |".dvi"|, or - |format_extension|*/ -{@+cur_area="";cur_ext=s; -cur_name=job_name;pack_cur_name; -} - -@ If some trouble arises when \TeX\ tries to open a file, the following -routine calls upon the user to supply another file name. Parameter~|s| -is used in the error message to identify the type of file; parameter~|e| -is the default extension if none is given. Upon exit from the routine, -variables |cur_name|, |cur_area|, |cur_ext|, and |name_of_file| are -ready for another attempt at file opening. - -@p void prompt_file_name(char *@!s, char *@!e) -{@+ -int k; /*index into |buffer|*/ -if (interaction==scroll_mode) wake_up_terminal; -if (strcmp(s,"input file name")==0) print_err("I can't find file `"); -@.I can't find file x@> -else print_err("I can't write on file `"); -@.I can't write on file x@> -print_file_name(cur_name, cur_area, cur_ext);print("'."); -if (strcmp(e,".tex")==0) show_context(); -print_nl("Please type another ");print(s); -@.Please type...@> -if (interaction < scroll_mode) - fatal_error("*** (job aborted, file error in nonstop mode)"); -@.job aborted, file error...@> -clear_terminal;prompt_input(": ");@<Scan file name in the buffer@>; -if (cur_ext[0]==0) cur_ext=e; -pack_cur_name; -} - -@ @<Scan file name in the buffer@>= -{@+begin_name();k=first; -while ((buffer[k]==' ')&&(k < last)) incr(k); -loop@+{@+if (k==last) goto done; - if (!more_name(buffer[k])) goto done; - incr(k); - } -done: end_name(); -} - -@ Here's an example of how these conventions are used. Whenever it is time to -ship out a box of stuff, we shall use the macro |ensure_dvi_open|. - -@d ensure_dvi_open if (output_file_name==0) - {@+if (job_name==0) open_log_file(); - pack_job_name(".dvi"); - while (!b_open_out(&dvi_file)) - prompt_file_name("file name for output",".dvi"); - output_file_name=b_make_name_string(&dvi_file); - } - -@<Glob...@>= -static byte_file @!dvi_file; /*the device-independent output goes here*/ -static str_number @!output_file_name; /*full name of the output file*/ -static str_number @!log_name; /*full name of the log file*/ - -@ @<Initialize the output...@>=output_file_name=0; - -@ The |open_log_file| routine is used to open the transcript file and to help -it catch up to what has previously been printed on the terminal. - -@p void open_log_file(void) -{@+int old_setting; /*previous |selector| setting*/ -int @!k; /*index into |months| and |buffer|*/ -int @!l; /*end of first input line*/ -char @!months[]=" JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC"; /*abbreviations of month names*/ -old_setting=selector; -if (job_name==0) job_name=s_no(c_job_name?c_job_name:"texput"); /* k\TeX\ */ -@.texput@> -pack_job_name(".log"); -while (!a_open_out(&log_file)) @<Try to get a different log file name@>; -log_name=a_make_name_string(&log_file); -selector=log_only;log_opened=true; -@<Print the banner line, including the date and time@>; -input_stack[input_ptr]=cur_input; /*make sure bottom level is in memory*/ -print_nl("**"); -@.**@> -l=input_stack[0].limit_field; /*last position of first line*/ -if (buffer[l]==end_line_char) decr(l); -for (k=1; k<=l; k++) printn(buffer[k]); -print_ln(); /*now the transcript file contains the first line of input*/ -selector=old_setting+2; /*|log_only| or |term_and_log|*/ -} - -@ Sometimes |open_log_file| is called at awkward moments when \TeX\ is -unable to print error messages or even to |show_context|. -The |prompt_file_name| routine can result in a |fatal_error|, but the |error| -routine will not be invoked because |log_opened| will be false. - -The normal idea of |batch_mode| is that nothing at all should be written -on the terminal. However, in the unusual case that -no log file could be opened, we make an exception and allow -an explanatory message to be seen. - -Incidentally, the program always refers to the log file as a `\.{transcript -file}', because some systems cannot use the extension `\.{.log}' for -this file. - -@<Try to get a different log file name@>= -{@+selector=term_only; -prompt_file_name("transcript file name",".log"); -} - -@ @<Print the banner...@>= -{@+wlog("%s",banner); -slow_print(format_ident);print(" "); -print_int(sys_day);print_char(' '); -for (k=3*sys_month-2; k<=3*sys_month; k++) wlog("%c",months[k]); -print_char(' ');print_int(sys_year);print_char(' '); -print_two(sys_time/60);print_char(':');print_two(sys_time%60); -if (eTeX_ex) - {@+;wlog_cr;wlog("entering extended mode"); - } -} - -@ Let's turn now to the procedure that is used to initiate file reading -when an `\.{\\input}' command is being processed. -Beware: For historic reasons, this code foolishly conserves a tiny bit -of string pool space; but that can confuse the interactive `\.E' option. -@^system dependencies@> - -@p static void start_input(void) /*\TeX\ will \.{\\input} something*/ -{@+ -scan_file_name(); /*set |cur_name| to desired file name*/ -if (cur_ext[0]==0) cur_ext=".tex"; -pack_cur_name; -loop@+{@+begin_file_reading(); /*set up |cur_file| and new level of input*/ - if (a_open_in(&cur_file)) goto done; - end_file_reading(); /*remove the level that didn't work*/ - prompt_file_name("input file name",".tex"); - } -done: name=a_make_name_string(&cur_file);@/ -source_filename_stack[in_open]=name; /* k\TeX\ */ -if (job_name==0) - {@+if (c_job_name==NULL) job_name=cur_name; - else job_name=s_no(c_job_name); open_log_file(); /* k\TeX\ */ - } /*|open_log_file| doesn't |show_context|, so |limit| - and |loc| needn't be set to meaningful values yet*/ -if (term_offset+length(name) > max_print_line-2) print_ln(); -else if ((term_offset > 0)||(file_offset > 0)) print_char(' '); -print_char('(');incr(open_parens);slow_print(name);update_terminal; -state=new_line; -if (name==str_ptr-1) /*conserve string pool space (but see note above)*/ - {@+flush_string;name=cur_name; - } -@<Read the first line of the new file@>; -} - -@ Here we have to remember to tell the |input_ln| routine not to -start with a |get|. If the file is empty, it is considered to -contain a single blank line. -@^system dependencies@> -@^empty line at end of file@> - -@<Read the first line...@>= -{@+line=1; -if (input_ln(&cur_file, false)) do_nothing; -firm_up_the_line(); -if (end_line_char_inactive) decr(limit); -else buffer[limit]=end_line_char; -first=limit+1;loc=start; -} - -@* Font metric data. -\TeX\ gets its knowledge about fonts from font metric files, also called -\.{TFM} files; the `\.T' in `\.{TFM}' stands for \TeX, -but other programs know about them too. -@:TFM files}{\.{TFM} files@> -@^font metric files@> - -The information in a \.{TFM} file appears in a sequence of 8-bit bytes. -Since the number of bytes is always a multiple of 4, we could -also regard the file as a sequence of 32-bit words, but \TeX\ uses the -byte interpretation. The format of \.{TFM} files was designed by -Lyle Ramshaw in 1980. The intent is to convey a lot of different kinds -@^Ramshaw, Lyle Harold@> -of information in a compact but useful form. - -@<Glob...@>= -static byte_file @!tfm_file; - -@ The first 24 bytes (6 words) of a \.{TFM} file contain twelve 16-bit -integers that give the lengths of the various subsequent portions -of the file. These twelve integers are, in order: -$$\vbox{\halign{\hfil#&$\null=\null$#\hfil\cr -|lf|&length of the entire file, in words;\cr -|lh|&length of the header data, in words;\cr -|bc|&smallest character code in the font;\cr -|ec|&largest character code in the font;\cr -|nw|&number of words in the width table;\cr -|nh|&number of words in the height table;\cr -|nd|&number of words in the depth table;\cr -|ni|&number of words in the italic correction table;\cr -|nl|&number of words in the lig/kern table;\cr -|nk|&number of words in the kern table;\cr -|ne|&number of words in the extensible character table;\cr -|np|&number of font parameter words.\cr}}$$ -They are all nonnegative and less than $2^{15}$. We must have |bc-1 <= ec <= 255|, -and -$$\hbox{|lf==6+lh+(ec-bc+1)+nw+nh+nd+ni+nl+nk+ne+np|.}$$ -Note that a font may contain as many as 256 characters (if |bc==0| and |ec==255|), -and as few as 0 characters (if |bc==ec+1|). - -Incidentally, when two or more 8-bit bytes are combined to form an integer of -16 or more bits, the most significant bytes appear first in the file. -This is called BigEndian order. -@!@^BigEndian order@> - -@ The rest of the \.{TFM} file may be regarded as a sequence of ten data -arrays having the informal specification -$$\def\arr$[#1]#2${\&{array} $[#1]$ \&{of} #2} -\def\PB#1{\arr#1} -\vbox{\halign{\hfil\\{#}&$\,:\,$#\hfil\cr -header&|[0 dotdot lh-1]@t\\{stuff}@>|\cr -char\_info&|[bc dotdot ec]char_info_word|\cr -width&|[0 dotdot nw-1]fix_word|\cr -height&|[0 dotdot nh-1]fix_word|\cr -depth&|[0 dotdot nd-1]fix_word|\cr -italic&|[0 dotdot ni-1]fix_word|\cr -lig\_kern&|[0 dotdot nl-1]lig_kern_command|\cr -kern&|[0 dotdot nk-1]fix_word|\cr -exten&|[0 dotdot ne-1]extensible_recipe|\cr -param&|[1 dotdot np]fix_word|\cr}}$$ -The most important data type used here is a |@!fix_word|, which is -a 32-bit representation of a binary fraction. A |fix_word| is a signed -quantity, with the two's complement of the entire word used to represent -negation. Of the 32 bits in a |fix_word|, exactly 12 are to the left of the -binary point; thus, the largest |fix_word| value is $2048-2^{-20}$, and -the smallest is $-2048$. We will see below, however, that all but two of -the |fix_word| values must lie between $-16$ and $+16$. - -@ The first data array is a block of header information, which contains -general facts about the font. The header must contain at least two words, -|header[0]| and |header[1]|, whose meaning is explained below. -Additional header information of use to other software routines might -also be included, but \TeX82 does not need to know about such details. -For example, 16 more words of header information are in use at the Xerox -Palo Alto Research Center; the first ten specify the character coding -scheme used (e.g., `\.{XEROX text}' or `\.{TeX math symbols}'), the next five -give the font identifier (e.g., `\.{HELVETICA}' or `\.{CMSY}'), and the -last gives the ``face byte.'' The program that converts \.{DVI} files -to Xerox printing format gets this information by looking at the \.{TFM} -file, which it needs to read anyway because of other information that -is not explicitly repeated in \.{DVI}~format. - -\yskip\hang|header[0]| is a 32-bit check sum that \TeX\ will copy into -the \.{DVI} output file. Later on when the \.{DVI} file is printed, -possibly on another computer, the actual font that gets used is supposed -to have a check sum that agrees with the one in the \.{TFM} file used by -\TeX. In this way, users will be warned about potential incompatibilities. -(However, if the check sum is zero in either the font file or the \.{TFM} -file, no check is made.) The actual relation between this check sum and -the rest of the \.{TFM} file is not important; the check sum is simply an -identification number with the property that incompatible fonts almost -always have distinct check sums. -@^check sum@> - -\yskip\hang|header[1]| is a |fix_word| containing the design size of -the font, in units of \TeX\ points. This number must be at least 1.0; it is -fairly arbitrary, but usually the design size is 10.0 for a ``10 point'' -font, i.e., a font that was designed to look best at a 10-point size, -whatever that really means. When a \TeX\ user asks for a font -`\.{at} $\delta$ \.{pt}', the effect is to override the design size -and replace it by $\delta$, and to multiply the $x$ and~$y$ coordinates -of the points in the font image by a factor of $\delta$ divided by the -design size. {\sl All other dimensions in the\/ \.{TFM} file are -|fix_word|\kern-1pt\ numbers in design-size units}, with the exception of -|param[1]| (which denotes the slant ratio). Thus, for example, the value -of |param[6]|, which defines the \.{em} unit, is often the |fix_word| value -$2^{20}=1.0$, since many fonts have a design size equal to one em. -The other dimensions must be less than 16 design-size units in absolute -value; thus, |header[1]| and |param[1]| are the only |fix_word| -entries in the whole \.{TFM} file whose first byte might be something -besides 0 or 255. - -@ Next comes the |char_info| array, which contains one |@!char_info_word| -per character. Each word in this part of the file contains six fields -packed into four bytes as follows. - -\yskip\hang first byte: |@!width_index| (8 bits)\par -\hang second byte: |@!height_index| (4 bits) times 16, plus |@!depth_index| - (4~bits)\par -\hang third byte: |@!italic_index| (6 bits) times 4, plus |@!tag| - (2~bits)\par -\hang fourth byte: |@!rem| (8 bits)\par -\yskip\noindent -The actual width of a character is \\{width}|[width_index]|, in design-size -units; this is a device for compressing information, since many characters -have the same width. Since it is quite common for many characters -to have the same height, depth, or italic correction, the \.{TFM} format -imposes a limit of 16 different heights, 16 different depths, and -64 different italic corrections. - -@!@^italic correction@> -The italic correction of a character has two different uses. -(a)~In ordinary text, the italic correction is added to the width only if -the \TeX\ user specifies `\.{\\/}' after the character. -(b)~In math formulas, the italic correction is always added to the width, -except with respect to the positioning of subscripts. - -Incidentally, the relation $\\{width}[0]=\\{height}[0]=\\{depth}[0]= -\\{italic}[0]=0$ should always hold, so that an index of zero implies a -value of zero. The |width_index| should never be zero unless the -character does not exist in the font, since a character is valid if and -only if it lies between |bc| and |ec| and has a nonzero |width_index|. - -@ The |tag| field in a |char_info_word| has four values that explain how to -interpret the |rem| field. - -\yskip\hangg|tag==0| (|no_tag|) means that |rem| is unused.\par -\hangg|tag==1| (|lig_tag|) means that this character has a ligature/kerning -program starting at position |rem| in the |lig_kern| array.\par -\hangg|tag==2| (|list_tag|) means that this character is part of a chain of -characters of ascending sizes, and not the largest in the chain. The -|rem| field gives the character code of the next larger character.\par -\hangg|tag==3| (|ext_tag|) means that this character code represents an -extensible character, i.e., a character that is built up of smaller pieces -so that it can be made arbitrarily large. The pieces are specified in -|@!exten[rem]|.\par -\yskip\noindent -Characters with |tag==2| and |tag==3| are treated as characters with |tag==0| -unless they are used in special circumstances in math formulas. For example, -the \.{\\sum} operation looks for a |list_tag|, and the \.{\\left} -operation looks for both |list_tag| and |ext_tag|. - -@d no_tag 0 /*vanilla character*/ -@d lig_tag 1 /*character has a ligature/kerning program*/ -@d list_tag 2 /*character has a successor in a charlist*/ -@d ext_tag 3 /*character is extensible*/ - -@ The |lig_kern| array contains instructions in a simple programming language -that explains what to do for special letter pairs. Each word in this array is a -|@!lig_kern_command| of four bytes. - -\yskip\hang first byte: |skip_byte|, indicates that this is the final program - step if the byte is 128 or more, otherwise the next step is obtained by - skipping this number of intervening steps.\par -\hang second byte: |next_char|, ``if |next_char| follows the current character, - then perform the operation and stop, otherwise continue.''\par -\hang third byte: |op_byte|, indicates a ligature step if less than~128, - a kern step otherwise.\par -\hang fourth byte: |rem|.\par -\yskip\noindent -In a kern step, an -additional space equal to |kern[256*(op_byte-128)+rem]| is inserted -between the current character and |next_char|. This amount is -often negative, so that the characters are brought closer together -by kerning; but it might be positive. - -There are eight kinds of ligature steps, having |op_byte| codes $4a+2b+c$ where -$0\le a\le b+c$ and $0\le b,c\le1$. The character whose code is -|rem| is inserted between the current character and |next_char|; -then the current character is deleted if $b=0$, and |next_char| is -deleted if $c=0$; then we pass over $a$~characters to reach the next -current character (which may have a ligature/kerning program of its own). - -If the very first instruction of the |lig_kern| array has |skip_byte==255|, -the |next_char| byte is the so-called boundary character of this font; -the value of |next_char| need not lie between |bc| and~|ec|. -If the very last instruction of the |lig_kern| array has |skip_byte==255|, -there is a special ligature/kerning program for a boundary character at the -left, beginning at location |256*op_byte+rem|. -The interpretation is that \TeX\ puts implicit boundary characters -before and after each consecutive string of characters from the same font. -These implicit characters do not appear in the output, but they can affect -ligatures and kerning. - -If the very first instruction of a character's |lig_kern| program has -|skip_byte > 128|, the program actually begins in location -|256*op_byte+rem|. This feature allows access to large |lig_kern| -arrays, because the first instruction must otherwise -appear in a location | <= 255|. - -Any instruction with |skip_byte > 128| in the |lig_kern| array must satisfy -the condition -$$\hbox{|256*op_byte+rem < nl|.}$$ -If such an instruction is encountered during -normal program execution, it denotes an unconditional halt; no ligature -or kerning command is performed. - -@d stop_flag qi(128) /*value indicating `\.{STOP}' in a lig/kern program*/ -@d kern_flag qi(128) /*op code for a kern step*/ -@d skip_byte(A) A.b0 -@d next_char(A) A.b1 -@d op_byte(A) A.b2 -@d rem_byte(A) A.b3 - -@ Extensible characters are specified by an |@!extensible_recipe|, which -consists of four bytes called |@!top|, |@!mid|, |@!bot|, and |@!rep| (in this -order). These bytes are the character codes of individual pieces used to -build up a large symbol. If |top|, |mid|, or |bot| are zero, they are not -present in the built-up result. For example, an extensible vertical line is -like an extensible bracket, except that the top and bottom pieces are missing. - -Let $T$, $M$, $B$, and $R$ denote the respective pieces, or an empty box -if the piece isn't present. Then the extensible characters have the form -$TR^kMR^kB$ from top to bottom, for some |k >= 0|, unless $M$ is absent; -in the latter case we can have $TR^kB$ for both even and odd values of~|k|. -The width of the extensible character is the width of $R$; and the -height-plus-depth is the sum of the individual height-plus-depths of the -components used, since the pieces are butted together in a vertical list. - -@d ext_top(A) A.b0 /*|top| piece in a recipe*/ -@d ext_mid(A) A.b1 /*|mid| piece in a recipe*/ -@d ext_bot(A) A.b2 /*|bot| piece in a recipe*/ -@d ext_rep(A) A.b3 /*|rep| piece in a recipe*/ - -@ The final portion of a \.{TFM} file is the |param| array, which is another -sequence of |fix_word| values. - -\yskip\hang|param[1]==slant| is the amount of italic slant, which is used -to help position accents. For example, |slant==.25| means that when you go -up one unit, you also go .25 units to the right. The |slant| is a pure -number; it's the only |fix_word| other than the design size itself that is -not scaled by the design size. - -\hang|param[2]==space| is the normal spacing between words in text. -Note that character |' '| in the font need not have anything to do with -blank spaces. - -\hang|param[3]==space_stretch| is the amount of glue stretching between words. - -\hang|param[4]==space_shrink| is the amount of glue shrinking between words. - -\hang|param[5]==x_height| is the size of one ex in the font; it is also -the height of letters for which accents don't have to be raised or lowered. - -\hang|param[6]==quad| is the size of one em in the font. - -\hang|param[7]==extra_space| is the amount added to |param[2]| at the -ends of sentences. - -\yskip\noindent -If fewer than seven parameters are present, \TeX\ sets the missing parameters -to zero. Fonts used for math symbols are required to have -additional parameter information, which is explained later. - -@d slant_code 1 -@d space_code 2 -@d space_stretch_code 3 -@d space_shrink_code 4 -@d x_height_code 5 -@d quad_code 6 -@d extra_space_code 7 - -@ So that is what \.{TFM} files hold. Since \TeX\ has to absorb such information -about lots of fonts, it stores most of the data in a large array called -|font_info|. Each item of |font_info| is a |memory_word|; the |fix_word| -data gets converted into |scaled| entries, while everything else goes into -words of type |four_quarters|. - -When the user defines \.{\\font\\f}, say, \TeX\ assigns an internal number -to the user's font~\.{\\f}. Adding this number to |font_id_base| gives the -|eqtb| location of a ``frozen'' control sequence that will always select -the font. - -@<Types...@>= -typedef uint8_t internal_font_number; /*|font| in a |char_node|*/ -typedef int32_t font_index; /*index into |font_info|*/ - -@ Here now is the (rather formidable) array of font arrays. - -@d non_char qi(256) /*a |halfword| code that can't match a real character*/ -@d non_address 0 /*a spurious |bchar_label|*/ - -@<Glob...@>= -memory_word @!font_info[font_mem_size+1]; - /*the big collection of font data*/ -static font_index @!fmem_ptr; /*first unused word of |font_info|*/ -static internal_font_number @!font_ptr; /*largest internal font number in use*/ -static four_quarters @!font_check0[font_max-font_base+1], *const @!font_check = @!font_check0-font_base; /*check sum*/ -scaled @!font_size0[font_max-font_base+1], *const @!font_size = @!font_size0-font_base; /*``at'' size*/ -scaled @!font_dsize0[font_max-font_base+1], *const @!font_dsize = @!font_dsize0-font_base; /*``design'' size*/ -static font_index @!font_params0[font_max-font_base+1], *const @!font_params = @!font_params0-font_base; /*how many font - parameters are present*/ -str_number @!font_name0[font_max-font_base+1], *const @!font_name = @!font_name0-font_base; /*name of the font*/ -static str_number @!font_area0[font_max-font_base+1], *const @!font_area = @!font_area0-font_base; /*area of the font*/ -static eight_bits @!font_bc0[font_max-font_base+1], *const @!font_bc = @!font_bc0-font_base; - /*beginning (smallest) character code*/ -static eight_bits @!font_ec0[font_max-font_base+1], *const @!font_ec = @!font_ec0-font_base; - /*ending (largest) character code*/ -pointer @!font_glue0[font_max-font_base+1], *const @!font_glue = @!font_glue0-font_base; - /*glue specification for interword space, |null| if not allocated*/ -static bool @!font_used0[font_max-font_base+1], *const @!font_used = @!font_used0-font_base; - /*has a character from this font actually appeared in the output?*/ -int @!hyphen_char0[font_max-font_base+1], *const @!hyphen_char = @!hyphen_char0-font_base; - /*current \.{\\hyphenchar} values*/ -static int @!skew_char0[font_max-font_base+1], *const @!skew_char = @!skew_char0-font_base; - /*current \.{\\skewchar} values*/ -static font_index @!bchar_label0[font_max-font_base+1], *const @!bchar_label = @!bchar_label0-font_base; - /*start of |lig_kern| program for left boundary character, - |non_address| if there is none*/ -static int16_t @!font_bchar0[font_max-font_base+1], *const @!font_bchar = @!font_bchar0-font_base; - /*boundary character, |non_char| if there is none*/ -static int16_t @!font_false_bchar0[font_max-font_base+1], *const @!font_false_bchar = @!font_false_bchar0-font_base; - /*|font_bchar| if it doesn't exist in the font, otherwise |non_char|*/ - -@ Besides the arrays just enumerated, we have directory arrays that make it -easy to get at the individual entries in |font_info|. For example, the -|char_info| data for character |c| in font |f| will be in -|font_info[char_base[f]+c].qqqq|; and if |w| is the |width_index| -part of this word (the |b0| field), the width of the character is -|font_info[width_base[f]+w].sc|. (These formulas assume that -|min_quarterword| has already been added to |c| and to |w|, since \TeX\ -stores its quarterwords that way.) - -@<Glob...@>= -int @!char_base0[font_max-font_base+1], *const @!char_base = @!char_base0-font_base; - /*base addresses for |char_info|*/ -int @!width_base0[font_max-font_base+1], *const @!width_base = @!width_base0-font_base; - /*base addresses for widths*/ -int @!height_base0[font_max-font_base+1], *const @!height_base = @!height_base0-font_base; - /*base addresses for heights*/ -int @!depth_base0[font_max-font_base+1], *const @!depth_base = @!depth_base0-font_base; - /*base addresses for depths*/ -static int @!italic_base0[font_max-font_base+1], *const @!italic_base = @!italic_base0-font_base; - /*base addresses for italic corrections*/ -static int @!lig_kern_base0[font_max-font_base+1], *const @!lig_kern_base = @!lig_kern_base0-font_base; - /*base addresses for ligature/kerning programs*/ -static int @!kern_base0[font_max-font_base+1], *const @!kern_base = @!kern_base0-font_base; - /*base addresses for kerns*/ -static int @!exten_base0[font_max-font_base+1], *const @!exten_base = @!exten_base0-font_base; - /*base addresses for extensible recipes*/ -int @!param_base0[font_max-font_base+1], *const @!param_base = @!param_base0-font_base; - /*base addresses for font parameters*/ - -@ @<Set init...@>= -for (k=font_base; k<=font_max; k++) font_used[k]=false; - -@ \TeX\ always knows at least one font, namely the null font. It has no -characters, and its seven parameters are all equal to zero. - -@<Initialize table...@>= -font_ptr=null_font;fmem_ptr=7; -font_name[null_font]=s_no("nullfont");font_area[null_font]=empty_string; -hyphen_char[null_font]='-';skew_char[null_font]=-1; -bchar_label[null_font]=non_address; -font_bchar[null_font]=non_char;font_false_bchar[null_font]=non_char; -font_bc[null_font]=1;font_ec[null_font]=0; -font_size[null_font]=0;font_dsize[null_font]=0; -char_base[null_font]=0;width_base[null_font]=0; -height_base[null_font]=0;depth_base[null_font]=0; -italic_base[null_font]=0;lig_kern_base[null_font]=0; -kern_base[null_font]=0;exten_base[null_font]=0; -font_glue[null_font]=null;font_params[null_font]=7; -param_base[null_font]=-1; -for (k=0; k<=6; k++) font_info[k].sc=0; - -@ @<Put each...@>= -primitive("nullfont", set_font, null_font); -@!@:null\_font\_}{\.{\\nullfont} primitive@> -text(frozen_null_font)=text(cur_val);eqtb[frozen_null_font]=eqtb[cur_val]; - -@ Of course we want to define macros that suppress the detail of how font -information is actually packed, so that we don't have to write things like -$$\hbox{|font_info[width_base[f]+font_info[char_base[f]+c].qqqq.b0].sc|}$$ -too often. The \.{WEB} definitions here make |char_info(f)(c)| the -|four_quarters| word of font information corresponding to character -|c| of font |f|. If |q| is such a word, |char_width(f)(q)| will be -the character's width; hence the long formula above is at least -abbreviated to -$$\hbox{|char_width(f)(char_info(f)(c))|.}$$ -Usually, of course, we will fetch |q| first and look at several of its -fields at the same time. - -The italic correction of a character will be denoted by -|char_italic(f)(q)|, so it is analogous to |char_width|. But we will get -at the height and depth in a slightly different way, since we usually want -to compute both height and depth if we want either one. The value of -|height_depth(q)| will be the 8-bit quantity -$$b=|height_index|\times16+|depth_index|,$$ and if |b| is such a byte we -will write |char_height(f)(b)| and |char_depth(f)(b)| for the height and -depth of the character |c| for which |q==char_info(f)(c)|. Got that? - -The tag field will be called |char_tag(q)|; the remainder byte will be -called |rem_byte(q)|, using a macro that we have already defined above. - -Access to a character's |width|, |height|, |depth|, and |tag| fields is -part of \TeX's inner loop, so we want these macros to produce code that is -as fast as possible under the circumstances. -@^inner loop@> - -@d char_info(A, B) font_info[char_base[A]+B].qqqq -@d char_width(A, B) font_info[width_base[A]+B.b0].sc -@d char_exists(A) (A.b0 > min_quarterword) -@d char_italic(A, B) font_info[italic_base[A]+(qo(B.b2))/4].sc -@d height_depth(A) qo(A.b1) -@d char_height(A, B) font_info[height_base[A]+(B)/16].sc -@d char_depth(A, B) font_info[depth_base[A]+(B)%16].sc -@d char_tag(A) ((qo(A.b2))%4) - -@ The global variable |null_character| is set up to be a word of -|char_info| for a character that doesn't exist. Such a word provides a -convenient way to deal with erroneous situations. - -@<Glob...@>= -static four_quarters @!null_character; /*nonexistent character information*/ - -@ @<Set init...@>= -null_character.b0=min_quarterword;null_character.b1=min_quarterword; -null_character.b2=min_quarterword;null_character.b3=min_quarterword; - -@ Here are some macros that help process ligatures and kerns. -We write |char_kern(f)(j)| to find the amount of kerning specified by -kerning command~|j| in font~|f|. If |j| is the |char_info| for a character -with a ligature/kern program, the first instruction of that program is either -|i==font_info[lig_kern_start(f)(j)]| or |font_info[lig_kern_restart(f)(i)]|, -depending on whether or not |skip_byte(i) <= stop_flag|. - -The constant |kern_base_offset| should be simplified, for \PASCAL\ compilers -that do not do local optimization. -@^system dependencies@> - -@d char_kern(A, B) font_info[kern_base[A]+256*op_byte(B)+rem_byte(B)].sc -@d kern_base_offset 256*(128+min_quarterword) -@d lig_kern_start(A, B) lig_kern_base[A]+B.b3 /*beginning of lig/kern program*/ -@d lig_kern_restart(A, B) lig_kern_base[A]+256*op_byte(B)+rem_byte(B)+32768-kern_base_offset - -@ Font parameters are referred to as |slant(f)|, |space(f)|, etc. - -@d param_end(A) param_base[A]].sc -@d param(A) font_info[A+param_end -@d slant param(slant_code) /*slant to the right, per unit distance upward*/ -@d space param(space_code) /*normal space between words*/ -@d space_stretch param(space_stretch_code) /*stretch between words*/ -@d space_shrink param(space_shrink_code) /*shrink between words*/ -@d x_height param(x_height_code) /*one ex*/ -@d quad param(quad_code) /*one em*/ -@d extra_space param(extra_space_code) /*additional space at end of sentence*/ - -@<The em width for |cur_font|@>=quad(cur_font) - -@ @<The x-height for |cur_font|@>=x_height(cur_font) - -@ \TeX\ checks the information of a \.{TFM} file for validity as the -file is being read in, so that no further checks will be needed when -typesetting is going on. The somewhat tedious subroutine that does this -is called |read_font_info|. It has four parameters: the user font -identifier~|u|, the file name and area strings |nom| and |aire|, and the -``at'' size~|s|. If |s|~is negative, it's the negative of a scale factor -to be applied to the design size; |s==-1000| is the normal case. -Otherwise |s| will be substituted for the design size; in this -case, |s| must be positive and less than $2048\rm\,pt$ -(i.e., it must be less than $2^{27}$ when considered as an integer). - -The subroutine opens and closes a global file variable called |tfm_file|. -It returns the value of the internal font number that was just loaded. -If an error is detected, an error message is issued and no font -information is stored; |null_font| is returned in this case. - -@d abort goto bad_tfm /*do this when the \.{TFM} data is wrong*/ - -@p static internal_font_number read_font_info(pointer @!u, str_number @!nom, char *@!aire, - scaled @!s) /*input a \.{TFM} file*/ -{@+ -int k; /*index into |font_info|*/ -bool @!file_opened; /*was |tfm_file| successfully opened?*/ -halfword @!lf, @!lh, @!bc, @!ec, @!nw, @!nh, @!nd, @!ni, @!nl, @!nk, @!ne, @!np; - /*sizes of subfiles*/ -internal_font_number @!f; /*the new font's number*/ -internal_font_number @!g; /*the number to return*/ -eight_bits @!a, @!b, @!c, @!d; /*byte variables*/ -four_quarters @!qw;scaled @!sw; /*accumulators*/ -int @!bch_label; /*left boundary start location, or infinity*/ -int @!bchar; /*boundary character, or 256*/ -scaled @!z; /*the design size or the ``at'' size*/ -int @!alpha;int @!beta; - /*auxiliary quantities used in fixed-point multiplication*/ -g=null_font;@/ -@<Read and check the font data; |abort| if the \.{TFM} file is malformed; if there's -no room for this font, say so and |goto done|; otherwise |incr(font_ptr)| and |goto -done|@>; -bad_tfm: @<Report that the font won't be loaded@>; -done: if (file_opened) b_close(&tfm_file); -return g; -} - -@ There are programs called \.{TFtoPL} and \.{PLtoTF} that convert -between the \.{TFM} format and a symbolic property-list format -that can be easily edited. These programs contain extensive -diagnostic information, so \TeX\ does not have to bother giving -precise details about why it rejects a particular \.{TFM} file. -@.TFtoPL@> @.PLtoTF@> - -@d start_font_error_message print_err("Font ");sprint_cs(u); - print_char('=');print_file_name(nom, aire,""); - if (s >= 0) - {@+print(" at ");print_scaled(s);print("pt"); - } - else if (s!=-1000) - {@+print(" scaled ");print_int(-s); - } - -@<Report that the font won't be loaded@>= -start_font_error_message; -@.Font x=xx not loadable...@> -if (file_opened) print(" not loadable: Bad metric (TFM) file"); -else print(" not loadable: Metric (TFM) file not found"); -help5("I wasn't able to read the size data for this font,",@/ -"so I will ignore the font specification.",@/ -"[Wizards can fix TFM files using TFtoPL/PLtoTF.]",@/ -"You might try inserting a different font spec;",@/ -"e.g., type `I\\font<same font id>=<substitute font name>'."); -error() - -@ @<Read and check...@>= -@<Open |tfm_file| for input@>; -@<Read the {\.{TFM}} size fields@>; -@<Use size fields to allocate font information@>; -@<Read the {\.{TFM}} header@>; -@<Read character data@>; -@<Read box dimensions@>; -@<Read ligature/kern program@>; -@<Read extensible character recipes@>; -@<Read font parameters@>; -@<Make final adjustments and |goto done|@>@; - -@ @<Open |tfm_file| for input@>= -file_opened=false; -pack_file_name(nom, "",".tfm"); /* k\TeX\ */ -if (!b_open_in(&tfm_file)) abort; -file_opened=true - -@ Note: A malformed \.{TFM} file might be shorter than it claims to be; -thus |eof(tfm_file)| might be true when |read_font_info| refers to -|tfm_file.d| or when it says |get(tfm_file)|. If such circumstances -cause system error messages, you will have to defeat them somehow, -for example by defining |fget| to be `\ignorespaces|{@+get(tfm_file);| -|if (eof(tfm_file)) abort;} |\unskip'. -@^system dependencies@> - -@d fget get(tfm_file) -@d fbyte tfm_file.d -@d read_sixteen(A) {@+A=fbyte; - if (A > 127) abort; - fget;A=A*0400+fbyte; - } -@d store_four_quarters(A) {@+fget;a=fbyte;qw.b0=qi(a); - fget;b=fbyte;qw.b1=qi(b); - fget;c=fbyte;qw.b2=qi(c); - fget;d=fbyte;qw.b3=qi(d); - A=qw; - } - -@ @<Read the {\.{TFM}} size fields@>= -{@+read_sixteen(lf); -fget;read_sixteen(lh); -fget;read_sixteen(bc); -fget;read_sixteen(ec); -if ((bc > ec+1)||(ec > 255)) abort; -if (bc > 255) /*|bc==256| and |ec==255|*/ - {@+bc=1;ec=0; - } -fget;read_sixteen(nw); -fget;read_sixteen(nh); -fget;read_sixteen(nd); -fget;read_sixteen(ni); -fget;read_sixteen(nl); -fget;read_sixteen(nk); -fget;read_sixteen(ne); -fget;read_sixteen(np); -if (lf!=6+lh+(ec-bc+1)+nw+nh+nd+ni+nl+nk+ne+np) abort; -if ((nw==0)||(nh==0)||(nd==0)||(ni==0)) abort; -} - -@ The preliminary settings of the index-offset variables |char_base|, -|width_base|, |lig_kern_base|, |kern_base|, and |exten_base| will be -corrected later by subtracting |min_quarterword| from them; and we will -subtract 1 from |param_base| too. It's best to forget about such anomalies -until later. - -@<Use size fields to allocate font information@>= -lf=lf-6-lh; /*|lf| words should be loaded into |font_info|*/ -if (np < 7) lf=lf+7-np; /*at least seven parameters will appear*/ -if ((font_ptr==font_max)||(fmem_ptr+lf > font_mem_size)) - @<Apologize for not loading the font, |goto done|@>; -f=font_ptr+1; -char_base[f]=fmem_ptr-bc; -width_base[f]=char_base[f]+ec+1; -height_base[f]=width_base[f]+nw; -depth_base[f]=height_base[f]+nh; -italic_base[f]=depth_base[f]+nd; -lig_kern_base[f]=italic_base[f]+ni; -kern_base[f]=lig_kern_base[f]+nl-kern_base_offset; -exten_base[f]=kern_base[f]+kern_base_offset+nk; -param_base[f]=exten_base[f]+ne - -@ @<Apologize for not loading...@>= -{@+start_font_error_message; -print(" not loaded: Not enough room left"); -@.Font x=xx not loaded...@> -help4("I'm afraid I won't be able to make use of this font,",@/ -"because my memory for character-size data is too small.",@/ -"If you're really stuck, ask a wizard to enlarge me.",@/ -"Or maybe try `I\\font<same font id>=<name of loaded font>'."); -error();goto done; -} - -@ Only the first two words of the header are needed by \TeX82. - -@<Read the {\.{TFM}} header@>= -{@+if (lh < 2) abort; -store_four_quarters(font_check[f]); -fget;read_sixteen(z); /*this rejects a negative design size*/ -fget;z=z*0400+fbyte;fget;z=(z*020)+(fbyte/020); -if (z < unity) abort; -while (lh > 2) - {@+fget;fget;fget;fget;decr(lh); /*ignore the rest of the header*/ - } -font_dsize[f]=z; -if (s!=-1000) - if (s >= 0) z=s; - else z=xn_over_d(z,-s, 1000); -font_size[f]=z; -} - -@ @<Read character data@>= -for (k=fmem_ptr; k<=width_base[f]-1; k++) - {@+store_four_quarters(font_info[k].qqqq); - if ((a >= nw)||(b/020 >= nh)||(b%020 >= nd)|| - (c/4 >= ni)) abort; - switch (c%4) { - case lig_tag: if (d >= nl) abort;@+break; - case ext_tag: if (d >= ne) abort;@+break; - case list_tag: @<Check for charlist cycle@>@;@+break; - default:do_nothing; /*|no_tag|*/ - } - } - -@ We want to make sure that there is no cycle of characters linked together -by |list_tag| entries, since such a cycle would get \TeX\ into an endless -loop. If such a cycle exists, the routine here detects it when processing -the largest character code in the cycle. - -@d check_byte_range(A) {@+if ((A < bc)||(A > ec)) abort;@+} -@d current_character_being_worked_on k+bc-fmem_ptr - -@<Check for charlist cycle@>= -{@+check_byte_range(d); -while (d < current_character_being_worked_on) - {@+qw=char_info(f, d); - /*N.B.: not |qi(d)|, since |char_base[f]| hasn't been adjusted yet*/ - if (char_tag(qw)!=list_tag) goto not_found; - d=qo(rem_byte(qw)); /*next character on the list*/ - } -if (d==current_character_being_worked_on) abort; /*yes, there's a cycle*/ -not_found: ;} - -@ A |fix_word| whose four bytes are $(a,b,c,d)$ from left to right represents -the number -$$x=\left\{\vcenter{\halign{$#$,\hfil\qquad&if $#$\hfil\cr -b\cdot2^{-4}+c\cdot2^{-12}+d\cdot2^{-20}&a=0;\cr --16+b\cdot2^{-4}+c\cdot2^{-12}+d\cdot2^{-20}&a=255.\cr}}\right.$$ -(No other choices of |a| are allowed, since the magnitude of a number in -design-size units must be less than 16.) We want to multiply this -quantity by the integer~|z|, which is known to be less than $2^{27}$. -If $|z|<2^{23}$, the individual multiplications $b\cdot z$, -$c\cdot z$, $d\cdot z$ cannot overflow; otherwise we will divide |z| by 2, -4, 8, or 16, to obtain a multiplier less than $2^{23}$, and we can -compensate for this later. If |z| has thereby been replaced by -$|z|^\prime=|z|/2^e$, let $\beta=2^{4-e}$; we shall compute -$$\lfloor(b+c\cdot2^{-8}+d\cdot2^{-16})\,z^\prime/\beta\rfloor$$ -if $a=0$, or the same quantity minus $\alpha=2^{4+e}z^\prime$ if $a=255$. -This calculation must be done exactly, in order to guarantee portability -of \TeX\ between computers. - -@d store_scaled(A) {@+fget;a=fbyte;fget;b=fbyte; - fget;c=fbyte;fget;d=fbyte;@/ - sw=(((((d*z)/0400)+(c*z))/0400)+(b*z))/beta; - if (a==0) A=sw;@+else if (a==255) A=sw-alpha;@+else abort; - } - -@<Read box dimensions@>= -{@+@<Replace |z| by $|z|^\prime$ and compute $\alpha,\beta$@>; -for (k=width_base[f]; k<=lig_kern_base[f]-1; k++) - store_scaled(font_info[k].sc); -if (font_info[width_base[f]].sc!=0) abort; /*\\{width}[0] must be zero*/ -if (font_info[height_base[f]].sc!=0) abort; /*\\{height}[0] must be zero*/ -if (font_info[depth_base[f]].sc!=0) abort; /*\\{depth}[0] must be zero*/ -if (font_info[italic_base[f]].sc!=0) abort; /*\\{italic}[0] must be zero*/ -} - -@ @<Replace |z|...@>= -{@+alpha=16; -while (z >= 040000000) - {@+z=z/2;alpha=alpha+alpha; - } -beta=256/alpha;alpha=alpha*z; -} - -@ @d check_existence(A) @t@>@;@/ - {@+check_byte_range(A); - qw=char_info(f, A); /*N.B.: not |qi(A)|*/ - if (!char_exists(qw)) abort; - } - -@<Read ligature/kern program@>= -bch_label=077777;bchar=256; -if (nl > 0) - {@+for (k=lig_kern_base[f]; k<=kern_base[f]+kern_base_offset-1; k++) - {@+store_four_quarters(font_info[k].qqqq); - if (a > 128) - {@+if (256*c+d >= nl) abort; - if (a==255) if (k==lig_kern_base[f]) bchar=b; - } - else{@+if (b!=bchar) check_existence(b); - if (c < 128) check_existence(d)@; /*check ligature*/ - else if (256*(c-128)+d >= nk) abort; /*check kern*/ - if (a < 128) if (k-lig_kern_base[f]+a+1 >= nl) abort; - } - } - if (a==255) bch_label=256*c+d; - } -for (k=kern_base[f]+kern_base_offset; k<=exten_base[f]-1; k++) - store_scaled(font_info[k].sc); - -@ @<Read extensible character recipes@>= -for (k=exten_base[f]; k<=param_base[f]-1; k++) - {@+store_four_quarters(font_info[k].qqqq); - if (a!=0) check_existence(a); - if (b!=0) check_existence(b); - if (c!=0) check_existence(c); - check_existence(d); - } - -@ We check to see that the \.{TFM} file doesn't end prematurely; but -no error message is given for files having more than |lf| words. - -@<Read font parameters@>= -{@+for (k=1; k<=np; k++) - if (k==1) /*the |slant| parameter is a pure number*/ - {@+fget;sw=fbyte;if (sw > 127) sw=sw-256; - fget;sw=sw*0400+fbyte;fget;sw=sw*0400+fbyte; - fget;font_info[param_base[f]].sc= - (sw*020)+(fbyte/020); - } - else store_scaled(font_info[param_base[f]+k-1].sc); -if (eof(tfm_file)) abort; -for (k=np+1; k<=7; k++) font_info[param_base[f]+k-1].sc=0; -} - -@ Now to wrap it up, we have checked all the necessary things about the \.{TFM} -file, and all we need to do is put the finishing touches on the data for -the new font. - -@d adjust(A) A[f]=qo(A[f]) - /*correct for the excess |min_quarterword| that was added*/ - -@<Make final adjustments...@>= -if (np >= 7) font_params[f]=np;@+else font_params[f]=7; -hyphen_char[f]=default_hyphen_char;skew_char[f]=default_skew_char; -if (bch_label < nl) bchar_label[f]=bch_label+lig_kern_base[f]; -else bchar_label[f]=non_address; -font_bchar[f]=qi(bchar); -font_false_bchar[f]=qi(bchar); -if (bchar <= ec) if (bchar >= bc) - {@+qw=char_info(f, bchar); /*N.B.: not |qi(bchar)|*/ - if (char_exists(qw)) font_false_bchar[f]=non_char; - } -font_name[f]=nom; -font_area[f]=s_no(aire); -font_bc[f]=bc;font_ec[f]=ec;font_glue[f]=null; -adjust(char_base);adjust(width_base);adjust(lig_kern_base); -adjust(kern_base);adjust(exten_base); -decr(param_base[f]); -fmem_ptr=fmem_ptr+lf;font_ptr=f;g=f;goto done - -@ Before we forget about the format of these tables, let's deal with two -of \TeX's basic scanning routines related to font information. - -@<Declare procedures that scan font-related stuff@>= -static void scan_font_ident(void) -{@+internal_font_number f; -halfword @!m; -@<Get the next non-blank non-call...@>; -if (cur_cmd==def_font) f=cur_font; -else if (cur_cmd==set_font) f=cur_chr; -else if (cur_cmd==def_family) - {@+m=cur_chr;scan_four_bit_int();f=equiv(m+cur_val); - } -else{@+print_err("Missing font identifier"); -@.Missing font identifier@> - help2("I was looking for a control sequence whose",@/ - "current meaning has been defined by \\font."); - back_error();f=null_font; - } -cur_val=f; -} - -@ The following routine is used to implement `\.{\\fontdimen} |n| |f|'. -The boolean parameter |writing| is set |true| if the calling program -intends to change the parameter value. - -@<Declare procedures that scan font-related stuff@>= -static void find_font_dimen(bool @!writing) - /*sets |cur_val| to |font_info| location*/ -{@+internal_font_number f; -int @!n; /*the parameter number*/ -scan_int();n=cur_val;scan_font_ident();f=cur_val; -if (n <= 0) cur_val=fmem_ptr; -else{@+if (writing&&(n <= space_shrink_code)&&@| - (n >= space_code)&&(font_glue[f]!=null)) - {@+delete_glue_ref(font_glue[f]); - font_glue[f]=null; - } - if (n > font_params[f]) - if (f < font_ptr) cur_val=fmem_ptr; - else@<Increase the number of parameters in the last font@>@; - else cur_val=n+param_base[f]; - } -@<Issue an error message if |cur_val=fmem_ptr|@>; -} - -@ @<Issue an error message if |cur_val=fmem_ptr|@>= -if (cur_val==fmem_ptr) - {@+print_err("Font ");printn_esc(font_id_text(f)); - print(" has only ");print_int(font_params[f]); - print(" fontdimen parameters"); -@.Font x has only...@> - help2("To increase the number of font parameters, you must",@/ - "use \\fontdimen immediately after the \\font is loaded."); - error(); - } - -@ @<Increase the number of parameters...@>= -{@+@/do@+{if (fmem_ptr==font_mem_size) - overflow("font memory", font_mem_size); -@:TeX capacity exceeded font memory}{\quad font memory@> -font_info[fmem_ptr].sc=0;incr(fmem_ptr);incr(font_params[f]); -}@+ while (!(n==font_params[f])); -cur_val=fmem_ptr-1; /*this equals |param_base[f]+font_params[f]|*/ -} - -@ When \TeX\ wants to typeset a character that doesn't exist, the -character node is not created; thus the output routine can assume -that characters exist when it sees them. The following procedure -prints a warning message unless the user has suppressed it. - -@p static void char_warning(internal_font_number @!f, eight_bits @!c) -{@+int old_setting; /*saved value of |tracing_online|*/ -if (tracing_lost_chars > 0) - {@+old_setting=tracing_online; - if (eTeX_ex&&(tracing_lost_chars > 1)) tracing_online=1; - {@+begin_diagnostic(); - print_nl("Missing character: There is no "); -@.Missing character@> - print_ASCII(c);print(" in font "); - slow_print(font_name[f]);print_char('!');end_diagnostic(false); - } - tracing_online=old_setting; - } -} - -@ Here is a function that returns a pointer to a character node for a -given character in a given font. If that character doesn't exist, -|null| is returned instead. - -@p pointer new_character(internal_font_number @!f, eight_bits @!c) -{@+ -pointer p; /*newly allocated node*/ -if (font_bc[f] <= c) if (font_ec[f] >= c) - if (char_exists(char_info(f, qi(c)))) - {@+p=get_avail();font(p)=f;character(p)=qi(c); - return p; - } -char_warning(f, c); -return null; -} - -@* Device-independent file format. -The most important output produced by a run of \TeX\ is the ``device -independent'' (\.{DVI}) file that specifies where characters and rules -are to appear on printed pages. The form of these files was designed by -David R. Fuchs in 1979. Almost any reasonable typesetting device can be -@^Fuchs, David Raymond@> -@:DVI\_files}{\.{DVI} files@> -driven by a program that takes \.{DVI} files as input, and dozens of such -\.{DVI}-to-whatever programs have been written. Thus, it is possible to -print the output of \TeX\ on many different kinds of equipment, using \TeX\ -as a device-independent ``front end.'' - -A \.{DVI} file is a stream of 8-bit bytes, which may be regarded as a -series of commands in a machine-like language. The first byte of each command -is the operation code, and this code is followed by zero or more bytes -that provide parameters to the command. The parameters themselves may consist -of several consecutive bytes; for example, the `|set_rule|' command has two -parameters, each of which is four bytes long. Parameters are usually -regarded as nonnegative integers; but four-byte-long parameters, -and shorter parameters that denote distances, can be -either positive or negative. Such parameters are given in two's complement -notation. For example, a two-byte-long distance parameter has a value between -$-2^{15}$ and $2^{15}-1$. As in \.{TFM} files, numbers that occupy -more than one byte position appear in BigEndian order. - -A \.{DVI} file consists of a ``preamble,'' followed by a sequence of one -or more ``pages,'' followed by a ``postamble.'' The preamble is simply a -|pre| command, with its parameters that define the dimensions used in the -file; this must come first. Each ``page'' consists of a |bop| command, -followed by any number of other commands that tell where characters are to -be placed on a physical page, followed by an |eop| command. The pages -appear in the order that \TeX\ generated them. If we ignore |nop| commands -and \\{fnt\_def} commands (which are allowed between any two commands in -the file), each |eop| command is immediately followed by a |bop| command, -or by a |post| command; in the latter case, there are no more pages in the -file, and the remaining bytes form the postamble. Further details about -the postamble will be explained later. - -Some parameters in \.{DVI} commands are ``pointers.'' These are four-byte -quantities that give the location number of some other byte in the file; -the first byte is number~0, then comes number~1, and so on. For example, -one of the parameters of a |bop| command points to the previous |bop|; -this makes it feasible to read the pages in backwards order, in case the -results are being directed to a device that stacks its output face up. -Suppose the preamble of a \.{DVI} file occupies bytes 0 to 99. Now if the -first page occupies bytes 100 to 999, say, and if the second -page occupies bytes 1000 to 1999, then the |bop| that starts in byte 1000 -points to 100 and the |bop| that starts in byte 2000 points to 1000. (The -very first |bop|, i.e., the one starting in byte 100, has a pointer of~$-1$.) - -@ The \.{DVI} format is intended to be both compact and easily interpreted -by a machine. Compactness is achieved by making most of the information -implicit instead of explicit. When a \.{DVI}-reading program reads the -commands for a page, it keeps track of several quantities: (a)~The current -font |f| is an integer; this value is changed only -by \\{fnt} and \\{fnt\_num} commands. (b)~The current position on the page -is given by two numbers called the horizontal and vertical coordinates, -|h| and |v|. Both coordinates are zero at the upper left corner of the page; -moving to the right corresponds to increasing the horizontal coordinate, and -moving down corresponds to increasing the vertical coordinate. Thus, the -coordinates are essentially Cartesian, except that vertical directions are -flipped; the Cartesian version of |(h, v)| would be |(h,-v)|. (c)~The -current spacing amounts are given by four numbers |w|, |x|, |y|, and |z|, -where |w| and~|x| are used for horizontal spacing and where |y| and~|z| -are used for vertical spacing. (d)~There is a stack containing -|(h, v, w, x, y, z)| values; the \.{DVI} commands |push| and |pop| are used to -change the current level of operation. Note that the current font~|f| is -not pushed and popped; the stack contains only information about -positioning. - -The values of |h|, |v|, |w|, |x|, |y|, and |z| are signed integers having up -to 32 bits, including the sign. Since they represent physical distances, -there is a small unit of measurement such that increasing |h| by~1 means -moving a certain tiny distance to the right. The actual unit of -measurement is variable, as explained below; \TeX\ sets things up so that -its \.{DVI} output is in sp units, i.e., scaled points, in agreement with -all the |scaled| dimensions in \TeX's data structures. - -@ Here is a list of all the commands that may appear in a \.{DVI} file. Each -command is specified by its symbolic name (e.g., |bop|), its opcode byte -(e.g., 139), and its parameters (if any). The parameters are followed -by a bracketed number telling how many bytes they occupy; for example, -`|p[4]|' means that parameter |p| is four bytes long. - -\yskip\hang|set_char_0| 0. Typeset character number~0 from font~|f| -such that the reference point of the character is at |(h, v)|. Then -increase |h| by the width of that character. Note that a character may -have zero or negative width, so one cannot be sure that |h| will advance -after this command; but |h| usually does increase. - -\yskip\hang\\{set\_char\_1} through \\{set\_char\_127} (opcodes 1 to 127). -Do the operations of |set_char_0|; but use the character whose number -matches the opcode, instead of character~0. - -\yskip\hang|set1| 128 |c[1]|. Same as |set_char_0|, except that character -number~|c| is typeset. \TeX82 uses this command for characters in the -range |128 <= c < 256|. - -\yskip\hang|@!set2| 129 |c[2]|. Same as |set1|, except that |c|~is two -bytes long, so it is in the range |0 <= c < 65536|. \TeX82 never uses this -command, but it should come in handy for extensions of \TeX\ that deal -with oriental languages. -@^oriental characters@>@^Chinese characters@>@^Japanese characters@> - -\yskip\hang|@!set3| 130 |c[3]|. Same as |set1|, except that |c|~is three -bytes long, so it can be as large as $2^{24}-1$. Not even the Chinese -language has this many characters, but this command might prove useful -in some yet unforeseen extension. - -\yskip\hang|@!set4| 131 |c[4]|. Same as |set1|, except that |c|~is four -bytes long. Imagine that. - -\yskip\hang|set_rule| 132 |a[4]| |b[4]|. Typeset a solid black rectangle -of height~|a| and width~|b|, with its bottom left corner at |(h, v)|. Then -set |h=h+b|. If either |a <= 0| or |b <= 0|, nothing should be typeset. Note -that if |b < 0|, the value of |h| will decrease even though nothing else happens. -See below for details about how to typeset rules so that consistency with -\MF\ is guaranteed. - -\yskip\hang|@!put1| 133 |c[1]|. Typeset character number~|c| from font~|f| -such that the reference point of the character is at |(h, v)|. (The `put' -commands are exactly like the `set' commands, except that they simply put out a -character or a rule without moving the reference point afterwards.) - -\yskip\hang|@!put2| 134 |c[2]|. Same as |set2|, except that |h| is not changed. - -\yskip\hang|@!put3| 135 |c[3]|. Same as |set3|, except that |h| is not changed. - -\yskip\hang|@!put4| 136 |c[4]|. Same as |set4|, except that |h| is not changed. - -\yskip\hang|put_rule| 137 |a[4]| |b[4]|. Same as |set_rule|, except that -|h| is not changed. - -\yskip\hang|nop| 138. No operation, do nothing. Any number of |nop|'s -may occur between \.{DVI} commands, but a |nop| cannot be inserted between -a command and its parameters or between two parameters. - -\yskip\hang|bop| 139 $c_0[4]$ $c_1[4]$ $\ldots$ $c_9[4]$ $p[4]$. Beginning -of a page: Set |(h, v, w, x, y, z)=(0, 0, 0, 0, 0, 0)| and set the stack empty. Set -the current font |f| to an undefined value. The ten $c_i$ parameters hold -the values of \.{\\count0} $\ldots$ \.{\\count9} in \TeX\ at the time -\.{\\shipout} was invoked for this page; they can be used to identify -pages, if a user wants to print only part of a \.{DVI} file. The parameter -|p| points to the previous |bop| in the file; the first -|bop| has $p=-1$. - -\yskip\hang|eop| 140. End of page: Print what you have read since the -previous |bop|. At this point the stack should be empty. (The \.{DVI}-reading -programs that drive most output devices will have kept a buffer of the -material that appears on the page that has just ended. This material is -largely, but not entirely, in order by |v| coordinate and (for fixed |v|) by -|h|~coordinate; so it usually needs to be sorted into some order that is -appropriate for the device in question.) - -\yskip\hang|push| 141. Push the current values of |(h, v, w, x, y, z)| onto the -top of the stack; do not change any of these values. Note that |f| is -not pushed. - -\yskip\hang|pop| 142. Pop the top six values off of the stack and assign -them respectively to |(h, v, w, x, y, z)|. The number of pops should never -exceed the number of pushes, since it would be highly embarrassing if the -stack were empty at the time of a |pop| command. - -\yskip\hang|right1| 143 |b[1]|. Set |h=h+b|, i.e., move right |b| units. -The parameter is a signed number in two's complement notation, |-128 <= b < 128|; -if |b < 0|, the reference point moves left. - -\yskip\hang|@!right2| 144 |b[2]|. Same as |right1|, except that |b| is a -two-byte quantity in the range |-32768 <= b < 32768|. - -\yskip\hang|@!right3| 145 |b[3]|. Same as |right1|, except that |b| is a -three-byte quantity in the range |@t$-2^{23}$@> <= b < @t$2^{23}$@>|. - -\yskip\hang|@!right4| 146 |b[4]|. Same as |right1|, except that |b| is a -four-byte quantity in the range |@t$-2^{31}$@> <= b < @t$2^{31}$@>|. - -\yskip\hang|w0| 147. Set |h=h+w|; i.e., move right |w| units. With luck, -this parameterless command will usually suffice, because the same kind of motion -will occur several times in succession; the following commands explain how -|w| gets particular values. - -\yskip\hang|w1| 148 |b[1]|. Set |w=b| and |h=h+b|. The value of |b| is a -signed quantity in two's complement notation, |-128 <= b < 128|. This command -changes the current |w|~spacing and moves right by |b|. - -\yskip\hang|@!w2| 149 |b[2]|. Same as |w1|, but |b| is two bytes long, -|-32768 <= b < 32768|. - -\yskip\hang|@!w3| 150 |b[3]|. Same as |w1|, but |b| is three bytes long, -|@t$-2^{23}$@> <= b < @t$2^{23}$@>|. - -\yskip\hang|@!w4| 151 |b[4]|. Same as |w1|, but |b| is four bytes long, -|@t$-2^{31}$@> <= b < @t$2^{31}$@>|. - -\yskip\hang|x0| 152. Set |h=h+x|; i.e., move right |x| units. The `|x|' -commands are like the `|w|' commands except that they involve |x| instead -of |w|. - -\yskip\hang|x1| 153 |b[1]|. Set |x=b| and |h=h+b|. The value of |b| is a -signed quantity in two's complement notation, |-128 <= b < 128|. This command -changes the current |x|~spacing and moves right by |b|. - -\yskip\hang|@!x2| 154 |b[2]|. Same as |x1|, but |b| is two bytes long, -|-32768 <= b < 32768|. - -\yskip\hang|@!x3| 155 |b[3]|. Same as |x1|, but |b| is three bytes long, -|@t$-2^{23}$@> <= b < @t$2^{23}$@>|. - -\yskip\hang|@!x4| 156 |b[4]|. Same as |x1|, but |b| is four bytes long, -|@t$-2^{31}$@> <= b < @t$2^{31}$@>|. - -\yskip\hang|down1| 157 |a[1]|. Set |v=v+a|, i.e., move down |a| units. -The parameter is a signed number in two's complement notation, |-128 <= a < 128|; -if |a < 0|, the reference point moves up. - -\yskip\hang|@!down2| 158 |a[2]|. Same as |down1|, except that |a| is a -two-byte quantity in the range |-32768 <= a < 32768|. - -\yskip\hang|@!down3| 159 |a[3]|. Same as |down1|, except that |a| is a -three-byte quantity in the range |@t$-2^{23}$@> <= a < @t$2^{23}$@>|. - -\yskip\hang|@!down4| 160 |a[4]|. Same as |down1|, except that |a| is a -four-byte quantity in the range |@t$-2^{31}$@> <= a < @t$2^{31}$@>|. - -\yskip\hang|y0| 161. Set |v=v+y|; i.e., move down |y| units. With luck, -this parameterless command will usually suffice, because the same kind of motion -will occur several times in succession; the following commands explain how -|y| gets particular values. - -\yskip\hang|y1| 162 |a[1]|. Set |y=a| and |v=v+a|. The value of |a| is a -signed quantity in two's complement notation, |-128 <= a < 128|. This command -changes the current |y|~spacing and moves down by |a|. - -\yskip\hang|@!y2| 163 |a[2]|. Same as |y1|, but |a| is two bytes long, -|-32768 <= a < 32768|. - -\yskip\hang|@!y3| 164 |a[3]|. Same as |y1|, but |a| is three bytes long, -|@t$-2^{23}$@> <= a < @t$2^{23}$@>|. - -\yskip\hang|@!y4| 165 |a[4]|. Same as |y1|, but |a| is four bytes long, -|@t$-2^{31}$@> <= a < @t$2^{31}$@>|. - -\yskip\hang|z0| 166. Set |v=v+z|; i.e., move down |z| units. The `|z|' commands -are like the `|y|' commands except that they involve |z| instead of |y|. - -\yskip\hang|z1| 167 |a[1]|. Set |z=a| and |v=v+a|. The value of |a| is a -signed quantity in two's complement notation, |-128 <= a < 128|. This command -changes the current |z|~spacing and moves down by |a|. - -\yskip\hang|@!z2| 168 |a[2]|. Same as |z1|, but |a| is two bytes long, -|-32768 <= a < 32768|. - -\yskip\hang|@!z3| 169 |a[3]|. Same as |z1|, but |a| is three bytes long, -|@t$-2^{23}$@> <= a < @t$2^{23}$@>|. - -\yskip\hang|@!z4| 170 |a[4]|. Same as |z1|, but |a| is four bytes long, -|@t$-2^{31}$@> <= a < @t$2^{31}$@>|. - -\yskip\hang|fnt_num_0| 171. Set |f=0|. Font 0 must previously have been -defined by a \\{fnt\_def} instruction, as explained below. - -\yskip\hang\\{fnt\_num\_1} through \\{fnt\_num\_63} (opcodes 172 to 234). Set -|f=1|, \dots, \hbox{|f=63|}, respectively. - -\yskip\hang|fnt1| 235 |k[1]|. Set |f=k|. \TeX82 uses this command for font -numbers in the range |64 <= k < 256|. - -\yskip\hang|@!fnt2| 236 |k[2]|. Same as |fnt1|, except that |k|~is two -bytes long, so it is in the range |0 <= k < 65536|. \TeX82 never generates this -command, but large font numbers may prove useful for specifications of -color or texture, or they may be used for special fonts that have fixed -numbers in some external coding scheme. - -\yskip\hang|@!fnt3| 237 |k[3]|. Same as |fnt1|, except that |k|~is three -bytes long, so it can be as large as $2^{24}-1$. - -\yskip\hang|@!fnt4| 238 |k[4]|. Same as |fnt1|, except that |k|~is four -bytes long; this is for the really big font numbers (and for the negative ones). - -\yskip\hang|xxx1| 239 |k[1]| |x[k]|. This command is undefined in -general; it functions as a $(k+2)$-byte |nop| unless special \.{DVI}-reading -programs are being used. \TeX82 generates |xxx1| when a short enough -\.{\\special} appears, setting |k| to the number of bytes being sent. It -is recommended that |x| be a string having the form of a keyword followed -by possible parameters relevant to that keyword. - -\yskip\hang|@!xxx2| 240 |k[2]| |x[k]|. Like |xxx1|, but |0 <= k < 65536|. - -\yskip\hang|@!xxx3| 241 |k[3]| |x[k]|. Like |xxx1|, but |0 <= k < @t$2^{24}$@>|. - -\yskip\hang|xxx4| 242 |k[4]| |x[k]|. Like |xxx1|, but |k| can be ridiculously -large. \TeX82 uses |xxx4| when sending a string of length 256 or more. - -\yskip\hang|fnt_def1| 243 |k[1]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|. -Define font |k|, where |0 <= k < 256|; font definitions will be explained shortly. - -\yskip\hang|@!fnt_def2| 244 |k[2]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|. -Define font |k|, where |0 <= k < 65536|. - -\yskip\hang|@!fnt_def3| 245 |k[3]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|. -Define font |k|, where |0 <= k < @t$2^{24}$@>|. - -\yskip\hang|@!fnt_def4| 246 |k[4]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|. -Define font |k|, where |@t$-2^{31}$@> <= k < @t$2^{31}$@>|. - -\yskip\hang|pre| 247 |i[1]| |num[4]| |den[4]| |mag[4]| |k[1]| |x[k]|. -Beginning of the preamble; this must come at the very beginning of the -file. Parameters |i|, |num|, |den|, |mag|, |k|, and |x| are explained below. - -\yskip\hang|post| 248. Beginning of the postamble, see below. - -\yskip\hang|post_post| 249. Ending of the postamble, see below. - -\yskip\noindent Commands 250--255 are undefined at the present time. - -@ @d set_char_0 0 /*typeset character 0 and move right*/ -@d set1 128 /*typeset a character and move right*/ -@d set_rule 132 /*typeset a rule and move right*/ -@d put_rule 137 /*typeset a rule*/ -@d nop 138 /*no operation*/ -@d bop 139 /*beginning of page*/ -@d eop 140 /*ending of page*/ -@d push 141 /*save the current positions*/ -@d pop 142 /*restore previous positions*/ -@d right1 143 /*move right*/ -@d w0 147 /*move right by |w|*/ -@d w1 148 /*move right and set |w|*/ -@d x0 152 /*move right by |x|*/ -@d x1 153 /*move right and set |x|*/ -@d down1 157 /*move down*/ -@d y0 161 /*move down by |y|*/ -@d y1 162 /*move down and set |y|*/ -@d z0 166 /*move down by |z|*/ -@d z1 167 /*move down and set |z|*/ -@d fnt_num_0 171 /*set current font to 0*/ -@d fnt1 235 /*set current font*/ -@d xxx1 239 /*extension to \.{DVI} primitives*/ -@d xxx4 242 /*potentially long extension to \.{DVI} primitives*/ -@d fnt_def1 243 /*define the meaning of a font number*/ -@d pre 247 /*preamble*/ -@d post 248 /*postamble beginning*/ -@d post_post 249 /*postamble ending*/ - -@ The preamble contains basic information about the file as a whole. As -stated above, there are six parameters: -$$\hbox{|@!i[1]| |@!num[4]| |@!den[4]| |@!mag[4]| |@!k[1]| |@!x[k]|.}$$ -The |i| byte identifies \.{DVI} format; currently this byte is always set -to~2. (The value |i==3| is currently used for an extended format that -allows a mixture of right-to-left and left-to-right typesetting. -Some day we will set |i==4|, when \.{DVI} format makes another -incompatible change---perhaps in the year 2048.) - -The next two parameters, |num| and |den|, are positive integers that define -the units of measurement; they are the numerator and denominator of a -fraction by which all dimensions in the \.{DVI} file could be multiplied -in order to get lengths in units of $10^{-7}$ meters. Since $\rm 7227{pt} = -254{cm}$, and since \TeX\ works with scaled points where there are $2^{16}$ -sp in a point, \TeX\ sets -$|num|/|den|=(254\cdot10^5)/(7227\cdot2^{16})=25400000/473628672$. -@^sp@> - -The |mag| parameter is what \TeX\ calls \.{\\mag}, i.e., 1000 times the -desired magnification. The actual fraction by which dimensions are -multiplied is therefore $|mag|\cdot|num|/1000|den|$. Note that if a \TeX\ -source document does not call for any `\.{true}' dimensions, and if you -change it only by specifying a different \.{\\mag} setting, the \.{DVI} -file that \TeX\ creates will be completely unchanged except for the value -of |mag| in the preamble and postamble. (Fancy \.{DVI}-reading programs allow -users to override the |mag|~setting when a \.{DVI} file is being printed.) - -Finally, |k| and |x| allow the \.{DVI} writer to include a comment, which is not -interpreted further. The length of comment |x| is |k|, where |0 <= k < 256|. - -@d id_byte 2 /*identifies the kind of \.{DVI} files described here*/ - -@ Font definitions for a given font number |k| contain further parameters -$$\hbox{|c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|.}$$ -The four-byte value |c| is the check sum that \TeX\ found in the \.{TFM} -file for this font; |c| should match the check sum of the font found by -programs that read this \.{DVI} file. -@^check sum@> - -Parameter |s| contains a fixed-point scale factor that is applied to -the character widths in font |k|; font dimensions in \.{TFM} files and -other font files are relative to this quantity, which is called the -``at size'' elsewhere in this documentation. The value of |s| is -always positive and less than $2^{27}$. It is given in the same units -as the other \.{DVI} dimensions, i.e., in sp when \TeX82 has made the -file. Parameter |d| is similar to |s|; it is the ``design size,'' and -(like~|s|) it is given in \.{DVI} units. Thus, font |k| is to be used -at $|mag|\cdot s/1000d$ times its normal size. - -The remaining part of a font definition gives the external name of the font, -which is an ASCII string of length |a+l|. The number |a| is the length -of the ``area'' or directory, and |l| is the length of the font name itself; -the standard local system font area is supposed to be used when |a==0|. -The |n| field contains the area in its first |a| bytes. - -Font definitions must appear before the first use of a particular font number. -Once font |k| is defined, it must not be defined again; however, we -shall see below that font definitions appear in the postamble as well as -in the pages, so in this sense each font number is defined exactly twice, -if at all. Like |nop| commands, font definitions can -appear before the first |bop|, or between an |eop| and a |bop|. - -@ Sometimes it is desirable to make horizontal or vertical rules line up -precisely with certain features in characters of a font. It is possible to -guarantee the correct matching between \.{DVI} output and the characters -generated by \MF\ by adhering to the following principles: (1)~The \MF\ -characters should be positioned so that a bottom edge or left edge that is -supposed to line up with the bottom or left edge of a rule appears at the -reference point, i.e., in row~0 and column~0 of the \MF\ raster. This -ensures that the position of the rule will not be rounded differently when -the pixel size is not a perfect multiple of the units of measurement in -the \.{DVI} file. (2)~A typeset rule of height $a>0$ and width $b>0$ -should be equivalent to a \MF-generated character having black pixels in -precisely those raster positions whose \MF\ coordinates satisfy -|0 <= x < @t$\alpha$@>b| and |0 <= y < @t$\alpha$@>a|, where $\alpha$ is the number -of pixels per \.{DVI} unit. -@:METAFONT}{\MF@> -@^alignment of rules with characters@> -@^rules aligning with characters@> - -@ The last page in a \.{DVI} file is followed by `|post|'; this command -introduces the postamble, which summarizes important facts that \TeX\ has -accumulated about the file, making it possible to print subsets of the data -with reasonable efficiency. The postamble has the form -$$\vbox{\halign{\hbox{#\hfil}\cr - |post| |p[4]| |num[4]| |den[4]| |mag[4]| |l[4]| |u[4]| |s[2]| |t[2]|\cr - $\langle\,$font definitions$\,\rangle$\cr - |post_post| |q[4]| |i[1]| 223's$[{\G}4]$\cr}}$$ -Here |p| is a pointer to the final |bop| in the file. The next three -parameters, |num|, |den|, and |mag|, are duplicates of the quantities that -appeared in the preamble. - -Parameters |l| and |u| give respectively the height-plus-depth of the tallest -page and the width of the widest page, in the same units as other dimensions -of the file. These numbers might be used by a \.{DVI}-reading program to -position individual ``pages'' on large sheets of film or paper; however, -the standard convention for output on normal size paper is to position each -page so that the upper left-hand corner is exactly one inch from the left -and the top. Experience has shown that it is unwise to design \.{DVI}-to-printer -software that attempts cleverly to center the output; a fixed position of -the upper left corner is easiest for users to understand and to work with. -Therefore |l| and~|u| are often ignored. - -Parameter |s| is the maximum stack depth (i.e., the largest excess of -|push| commands over |pop| commands) needed to process this file. Then -comes |t|, the total number of pages (|bop| commands) present. - -The postamble continues with font definitions, which are any number of -\\{fnt\_def} commands as described above, possibly interspersed with |nop| -commands. Each font number that is used in the \.{DVI} file must be defined -exactly twice: Once before it is first selected by a \\{fnt} command, and once -in the postamble. - -@ The last part of the postamble, following the |post_post| byte that -signifies the end of the font definitions, contains |q|, a pointer to the -|post| command that started the postamble. An identification byte, |i|, -comes next; this currently equals~2, as in the preamble. - -The |i| byte is followed by four or more bytes that are all equal to -the decimal number 223 (i.e., 0337 in octal). \TeX\ puts out four to seven of -these trailing bytes, until the total length of the file is a multiple of -four bytes, since this works out best on machines that pack four bytes per -word; but any number of 223's is allowed, as long as there are at least four -of them. In effect, 223 is a sort of signature that is added at the very end. -@^Fuchs, David Raymond@> - -This curious way to finish off a \.{DVI} file makes it feasible for -\.{DVI}-reading programs to find the postamble first, on most computers, -even though \TeX\ wants to write the postamble last. Most operating -systems permit random access to individual words or bytes of a file, so -the \.{DVI} reader can start at the end and skip backwards over the 223's -until finding the identification byte. Then it can back up four bytes, read -|q|, and move to byte |q| of the file. This byte should, of course, -contain the value 248 (|post|); now the postamble can be read, so the -\.{DVI} reader can discover all the information needed for typesetting the -pages. Note that it is also possible to skip through the \.{DVI} file at -reasonably high speed to locate a particular page, if that proves -desirable. This saves a lot of time, since \.{DVI} files used in production -jobs tend to be large. - -Unfortunately, however, standard \PASCAL\ does not include the ability to -@^system dependencies@> -access a random position in a file, or even to determine the length of a file. -Almost all systems nowadays provide the necessary capabilities, so \.{DVI} -format has been designed to work most efficiently with modern operating systems. -But if \.{DVI} files have to be processed under the restrictions of standard -\PASCAL, one can simply read them from front to back, since the necessary -header information is present in the preamble and in the font definitions. -(The |l| and |u| and |s| and |t| parameters, which appear only in the -postamble, are ``frills'' that are handy but not absolutely necessary.) - -@* Shipping pages out. -After considering \TeX's eyes and stomach, we come now to the bowels. -@^bowels@> - -The |ship_out| procedure is given a pointer to a box; its mission is -to describe that box in \.{DVI} form, outputting a ``page'' to |dvi_file|. -The \.{DVI} coordinates $(h,v)=(0,0)$ should correspond to the upper left -corner of the box being shipped. - -Since boxes can be inside of boxes inside of boxes, the main work of -|ship_out| is done by two mutually recursive routines, |hlist_out| -and |vlist_out|, which traverse the hlists and vlists inside of horizontal -and vertical boxes. - -As individual pages are being processed, we need to accumulate -information about the entire set of pages, since such statistics must be -reported in the postamble. The global variables |total_pages|, |max_v|, -|max_h|, |max_push|, and |last_bop| are used to record this information. - -The variable |doing_leaders| is |true| while leaders are being output. -The variable |dead_cycles| contains the number of times an output routine -has been initiated since the last |ship_out|. - -A few additional global variables are also defined here for use in -|vlist_out| and |hlist_out|. They could have been local variables, but -that would waste stack space when boxes are deeply nested, since the -values of these variables are not needed during recursive calls. -@^recursion@> - -@<Glob...@>= -static int @!total_pages; /*the number of pages that have been shipped out*/ -static scaled @!max_v; /*maximum height-plus-depth of pages shipped so far*/ -static scaled @!max_h; /*maximum width of pages shipped so far*/ -static int @!max_push; /*deepest nesting of |push| commands encountered so far*/ -static int @!last_bop; /*location of previous |bop| in the \.{DVI} output*/ -static int @!dead_cycles; /*recent outputs that didn't ship anything out*/ -bool @!doing_leaders; /*are we inside a leader box?*/ -@# -static quarterword @!c, @!f; /*character and font in current |char_node|*/ -static scaled @!rule_ht, @!rule_dp, @!rule_wd; /*size of current rule being output*/ -static pointer @!g; /*current glue specification*/ -static int @!lq, @!lr; /*quantities used in calculations for leaders*/ - -@ @<Set init...@>= -total_pages=0;max_v=0;max_h=0;max_push=0;last_bop=-1; -doing_leaders=false;dead_cycles=0;cur_s=-1; - -@ The \.{DVI} bytes are output to a buffer instead of being written directly -to the output file. This makes it possible to reduce the overhead of -subroutine calls, thereby measurably speeding up the computation, since -output of \.{DVI} bytes is part of \TeX's inner loop. And it has another -advantage as well, since we can change instructions in the buffer in order to -make the output more compact. For example, a `|down2|' command can be -changed to a `|y2|', thereby making a subsequent `|y0|' command possible, -saving two bytes. - -The output buffer is divided into two parts of equal size; the bytes found -in |dvi_buf[0 dotdot half_buf-1]| constitute the first half, and those in -|dvi_buf[half_buf dotdot dvi_buf_size-1]| constitute the second. The global -variable |dvi_ptr| points to the position that will receive the next -output byte. When |dvi_ptr| reaches |dvi_limit|, which is always equal -to one of the two values |half_buf| or |dvi_buf_size|, the half buffer that -is about to be invaded next is sent to the output and |dvi_limit| is -changed to its other value. Thus, there is always at least a half buffer's -worth of information present, except at the very beginning of the job. - -Bytes of the \.{DVI} file are numbered sequentially starting with 0; -the next byte to be generated will be number |dvi_offset+dvi_ptr|. -A byte is present in the buffer only if its number is | >= dvi_gone|. - -@<Types...@>= -typedef int16_t dvi_index; /*an index into the output buffer*/ - -@ Some systems may find it more efficient to make |dvi_buf| a || -array, since output of four bytes at once may be facilitated. -@^system dependencies@> - -@<Glob...@>= -static eight_bits @!dvi_buf[dvi_buf_size+1]; /*buffer for \.{DVI} output*/ -static dvi_index @!half_buf; /*half of |dvi_buf_size|*/ -static dvi_index @!dvi_limit; /*end of the current half buffer*/ -static dvi_index @!dvi_ptr; /*the next available buffer address*/ -static int @!dvi_offset; /*|dvi_buf_size| times the number of times the - output buffer has been fully emptied*/ -static int @!dvi_gone; /*the number of bytes already output to |dvi_file|*/ - -@ Initially the buffer is all in one piece; we will output half of it only -after it first fills up. - -@<Set init...@>= -half_buf=dvi_buf_size/2;dvi_limit=dvi_buf_size;dvi_ptr=0; -dvi_offset=0;dvi_gone=0; - -@ The actual output of |dvi_buf[a dotdot b]| to |dvi_file| is performed by calling -|write_dvi(a, b)|. For best results, this procedure should be optimized to -run as fast as possible on each particular system, since it is part of -\TeX's inner loop. It is safe to assume that |a| and |b+1| will both be -multiples of 4 when |write_dvi(a, b)| is called; therefore it is possible on -many machines to use efficient methods to pack four bytes per word and to -output an array of words with one system call. -@^system dependencies@> -@^inner loop@> -@^defecation@> - -@p static void write_dvi(dvi_index @!a, dvi_index @!b) -{@+int k; -for (k=a; k<=b; k++) pascal_write(dvi_file, "%c", dvi_buf[k]); -} - -@ To put a byte in the buffer without paying the cost of invoking a procedure -each time, we use the macro |dvi_out|. - -@d dvi_out(A) @+{@+dvi_buf[dvi_ptr]=A;incr(dvi_ptr); - if (dvi_ptr==dvi_limit) dvi_swap(); - } - -@p static void dvi_swap(void) /*outputs half of the buffer*/ -{@+if (dvi_limit==dvi_buf_size) - {@+write_dvi(0, half_buf-1);dvi_limit=half_buf; - dvi_offset=dvi_offset+dvi_buf_size;dvi_ptr=0; - } -else{@+write_dvi(half_buf, dvi_buf_size-1);dvi_limit=dvi_buf_size; - } -dvi_gone=dvi_gone+half_buf; -} - -@ Here is how we clean out the buffer when \TeX\ is all through; |dvi_ptr| -will be a multiple of~4. - -@<Empty the last bytes out of |dvi_buf|@>= -if (dvi_limit==half_buf) write_dvi(half_buf, dvi_buf_size-1); -if (dvi_ptr > 0) write_dvi(0, dvi_ptr-1) - -@ The |dvi_four| procedure outputs four bytes in two's complement notation, -without risking arithmetic overflow. - -@p static void dvi_four(int @!x) -{@+if (x >= 0) dvi_out(x/0100000000)@; -else{@+x=x+010000000000; - x=x+010000000000; - dvi_out((x/0100000000)+128); - } -x=x%0100000000;dvi_out(x/0200000); -x=x%0200000;dvi_out(x/0400); -dvi_out(x%0400); -} - -@ A mild optimization of the output is performed by the |dvi_pop| -routine, which issues a |pop| unless it is possible to cancel a -`|push| |pop|' pair. The parameter to |dvi_pop| is the byte address -following the old |push| that matches the new |pop|. - -@p static void dvi_pop(int @!l) -{@+if ((l==dvi_offset+dvi_ptr)&&(dvi_ptr > 0)) decr(dvi_ptr); -else dvi_out(pop); -} - -@ Here's a procedure that outputs a font definition. Since \TeX82 uses at -most 256 different fonts per job, |fnt_def1| is always used as the command code. - -@p static void dvi_font_def(internal_font_number @!f) -{@+int k; /*index into |str_pool|*/ -dvi_out(fnt_def1); -dvi_out(f-font_base-1);@/ -dvi_out(qo(font_check[f].b0)); -dvi_out(qo(font_check[f].b1)); -dvi_out(qo(font_check[f].b2)); -dvi_out(qo(font_check[f].b3));@/ -dvi_four(font_size[f]); -dvi_four(font_dsize[f]);@/ -dvi_out(length(font_area[f])); -dvi_out(length(font_name[f])); -@<Output the font name whose internal number is |f|@>; -} - -@ @<Output the font name whose internal number is |f|@>= -for (k=str_start[font_area[f]]; k<=str_start[font_area[f]+1]-1; k++) - dvi_out(so(str_pool[k])); -for (k=str_start[font_name[f]]; k<=str_start[font_name[f]+1]-1; k++) - dvi_out(so(str_pool[k])) - -@ Versions of \TeX\ intended for small computers might well choose to omit -the ideas in the next few parts of this program, since it is not really -necessary to optimize the \.{DVI} code by making use of the |w0|, |x0|, -|y0|, and |z0| commands. Furthermore, the algorithm that we are about to -describe does not pretend to give an optimum reduction in the length -of the \.{DVI} code; after all, speed is more important than compactness. -But the method is surprisingly effective, and it takes comparatively little -time. - -We can best understand the basic idea by first considering a simpler problem -that has the same essential characteristics. Given a sequence of digits, -say $3\,1\,4\,1\,5\,9\,2\,6\,5\,3\,5\,8\,9$, we want to assign subscripts -$d$, $y$, or $z$ to each digit so as to maximize the number of ``$y$-hits'' -and ``$z$-hits''; a $y$-hit is an instance of two appearances of the same -digit with the subscript $y$, where no $y$'s intervene between the two -appearances, and a $z$-hit is defined similarly. For example, the sequence -above could be decorated with subscripts as follows: -$$3_z\,1_y\,4_d\,1_y\,5_y\,9_d\,2_d\,6_d\,5_y\,3_z\,5_y\,8_d\,9_d.$$ -There are three $y$-hits ($1_y\ldots1_y$ and $5_y\ldots5_y\ldots5_y$) and -one $z$-hit ($3_z\ldots3_z$); there are no $d$-hits, since the two appearances -of $9_d$ have $d$'s between them, but we don't count $d$-hits so it doesn't -matter how many there are. These subscripts are analogous to the \.{DVI} -commands called \\{down}, $y$, and $z$, and the digits are analogous to -different amounts of vertical motion; a $y$-hit or $z$-hit corresponds to -the opportunity to use the one-byte commands |y0| or |z0| in a \.{DVI} file. - -\TeX's method of assigning subscripts works like this: Append a new digit, -say $\delta$, to the right of the sequence. Now look back through the -sequence until one of the following things happens: (a)~You see -$\delta_y$ or $\delta_z$, and this was the first time you encountered a -$y$ or $z$ subscript, respectively. Then assign $y$ or $z$ to the new -$\delta$; you have scored a hit. (b)~You see $\delta_d$, and no $y$ -subscripts have been encountered so far during this search. Then change -the previous $\delta_d$ to $\delta_y$ (this corresponds to changing a -command in the output buffer), and assign $y$ to the new $\delta$; it's -another hit. (c)~You see $\delta_d$, and a $y$ subscript has been seen -but not a $z$. Change the previous $\delta_d$ to $\delta_z$ and assign -$z$ to the new $\delta$. (d)~You encounter both $y$ and $z$ subscripts -before encountering a suitable $\delta$, or you scan all the way to the -front of the sequence. Assign $d$ to the new $\delta$; this assignment may -be changed later. - -The subscripts $3_z\,1_y\,4_d\ldots\,$ in the example above were, in fact, -produced by this procedure, as the reader can verify. (Go ahead and try it.) - -@ In order to implement such an idea, \TeX\ maintains a stack of pointers -to the \\{down}, $y$, and $z$ commands that have been generated for the -current page. And there is a similar stack for \\{right}, |w|, and |x| -commands. These stacks are called the down stack and right stack, and their -top elements are maintained in the variables |down_ptr| and |right_ptr|. - -Each entry in these stacks contains four fields: The |width| field is -the amount of motion down or to the right; the |location| field is the -byte number of the \.{DVI} command in question (including the appropriate -|dvi_offset|); the |link| field points to the next item below this one -on the stack; and the |info| field encodes the options for possible change -in the \.{DVI} command. - -@d movement_node_size 3 /*number of words per entry in the down and right stacks*/ -@d location(A) mem[A+2].i /*\.{DVI} byte number for a movement command*/ - -@<Glob...@>= -static pointer @!down_ptr, @!right_ptr; /*heads of the down and right stacks*/ - -@ @<Set init...@>= -down_ptr=null;right_ptr=null; - -@ Here is a subroutine that produces a \.{DVI} command for some specified -downward or rightward motion. It has two parameters: |w| is the amount -of motion, and |o| is either |down1| or |right1|. We use the fact that -the command codes have convenient arithmetic properties: |y1-down1==w1-right1| -and |z1-down1==x1-right1|. - -@p static void movement(scaled @!w, eight_bits @!o) -{@+ -small_number mstate; /*have we seen a |y| or |z|?*/ -pointer @!p, @!q; /*current and top nodes on the stack*/ -int @!k; /*index into |dvi_buf|, modulo |dvi_buf_size|*/ -q=get_node(movement_node_size); /*new node for the top of the stack*/ -width(q)=w;location(q)=dvi_offset+dvi_ptr; -if (o==down1) - {@+link(q)=down_ptr;down_ptr=q; - } -else{@+link(q)=right_ptr;right_ptr=q; - } -@<Look at the other stack entries until deciding what sort of \.{DVI} command to generate; -|goto found| if node |p| is a ``hit''@>; -@<Generate a |down| or |right| command for |w| and |return|@>; -found: @<Generate a |y0| or |z0| command in order to reuse a previous appearance of~|w|@>; -} - -@ The |info| fields in the entries of the down stack or the right stack -have six possible settings: |y_here| or |z_here| mean that the \.{DVI} -command refers to |y| or |z|, respectively (or to |w| or |x|, in the -case of horizontal motion); |yz_OK| means that the \.{DVI} command is -\\{down} (or \\{right}) but can be changed to either |y| or |z| (or -to either |w| or |x|); |y_OK| means that it is \\{down} and can be changed -to |y| but not |z|; |z_OK| is similar; and |d_fixed| means it must stay -\\{down}. - -The four settings |yz_OK|, |y_OK|, |z_OK|, |d_fixed| would not need to -be distinguished from each other if we were simply solving the -digit-subscripting problem mentioned above. But in \TeX's case there is -a complication because of the nested structure of |push| and |pop| -commands. Suppose we add parentheses to the digit-subscripting problem, -redefining hits so that $\delta_y\ldots \delta_y$ is a hit if all $y$'s between -the $\delta$'s are enclosed in properly nested parentheses, and if the -parenthesis level of the right-hand $\delta_y$ is deeper than or equal to -that of the left-hand one. Thus, `(' and `)' correspond to `|push|' -and `|pop|'. Now if we want to assign a subscript to the final 1 in the -sequence -$$2_y\,7_d\,1_d\,(\,8_z\,2_y\,8_z\,)\,1$$ -we cannot change the previous $1_d$ to $1_y$, since that would invalidate -the $2_y\ldots2_y$ hit. But we can change it to $1_z$, scoring a hit -since the intervening $8_z$'s are enclosed in parentheses. - -The program below removes movement nodes that are introduced after a |push|, -before it outputs the corresponding |pop|. - -@d y_here 1 /*|info| when the movement entry points to a |y| command*/ -@d z_here 2 /*|info| when the movement entry points to a |z| command*/ -@d yz_OK 3 /*|info| corresponding to an unconstrained \\{down} command*/ -@d y_OK 4 /*|info| corresponding to a \\{down} that can't become a |z|*/ -@d z_OK 5 /*|info| corresponding to a \\{down} that can't become a |y|*/ -@d d_fixed 6 /*|info| corresponding to a \\{down} that can't change*/ - -@ When the |movement| procedure gets to the label |found|, the value of -|info(p)| will be either |y_here| or |z_here|. If it is, say, |y_here|, -the procedure generates a |y0| command (or a |w0| command), and marks -all |info| fields between |q| and |p| so that |y| is not OK in that range. - -@<Generate a |y0| or |z0| command...@>= -info(q)=info(p); -if (info(q)==y_here) - {@+dvi_out(o+y0-down1); /*|y0| or |w0|*/ - while (link(q)!=p) - {@+q=link(q); - switch (info(q)) { - case yz_OK: info(q)=z_OK;@+break; - case y_OK: info(q)=d_fixed;@+break; - default:do_nothing; - } - } - } -else{@+dvi_out(o+z0-down1); /*|z0| or |x0|*/ - while (link(q)!=p) - {@+q=link(q); - switch (info(q)) { - case yz_OK: info(q)=y_OK;@+break; - case z_OK: info(q)=d_fixed;@+break; - default:do_nothing; - } - } - } - -@ @<Generate a |down| or |right|...@>= -info(q)=yz_OK; -if (abs(w) >= 040000000) - {@+dvi_out(o+3); /*|down4| or |right4|*/ - dvi_four(w);return; - } -if (abs(w) >= 0100000) - {@+dvi_out(o+2); /*|down3| or |right3|*/ - if (w < 0) w=w+0100000000; - dvi_out(w/0200000);w=w%0200000;goto label2; - } -if (abs(w) >= 0200) - {@+dvi_out(o+1); /*|down2| or |right2|*/ - if (w < 0) w=w+0200000; - goto label2; - } -dvi_out(o); /*|down1| or |right1|*/ -if (w < 0) w=w+0400; -goto label1; -label2: dvi_out(w/0400); -label1: dvi_out(w%0400);return - -@ As we search through the stack, we are in one of three states, -|y_seen|, |z_seen|, or |none_seen|, depending on whether we have -encountered |y_here| or |z_here| nodes. These states are encoded as -multiples of 6, so that they can be added to the |info| fields for quick -decision-making. -@^inner loop@> - -@d none_seen 0 /*no |y_here| or |z_here| nodes have been encountered yet*/ -@d y_seen 6 /*we have seen |y_here| but not |z_here|*/ -@d z_seen 12 /*we have seen |z_here| but not |y_here|*/ - -@<Look at the other stack entries until deciding...@>= -p=link(q);mstate=none_seen; -while (p!=null) - {@+if (width(p)==w) @<Consider a node with matching width; |goto found| if it's -a hit@>@; - else switch (mstate+info(p)) { - case none_seen+y_here: mstate=y_seen;@+break; - case none_seen+z_here: mstate=z_seen;@+break; - case y_seen+z_here: case z_seen+y_here: goto not_found; - default:do_nothing; - } - p=link(p); - } -not_found: - -@ We might find a valid hit in a |y| or |z| byte that is already gone -from the buffer. But we can't change bytes that are gone forever; ``the -moving finger writes, $\ldots\,\,$.'' - -@<Consider a node with matching width...@>= -switch (mstate+info(p)) { -case none_seen+yz_OK: case none_seen+y_OK: case z_seen+yz_OK: case z_seen+y_OK: @t@>@;@/ - if (location(p) < dvi_gone) goto not_found; - else@<Change buffered instruction to |y| or |w| and |goto found|@>@;@+break; -case none_seen+z_OK: case y_seen+yz_OK: case y_seen+z_OK: @t@>@;@/ - if (location(p) < dvi_gone) goto not_found; - else@<Change buffered instruction to |z| or |x| and |goto found|@>@;@+break; -case none_seen+y_here: case none_seen+z_here: case y_seen+z_here: case z_seen+y_here: goto found; -default:do_nothing; -} - -@ @<Change buffered instruction to |y| or |w| and |goto found|@>= -{@+k=location(p)-dvi_offset; -if (k < 0) k=k+dvi_buf_size; -dvi_buf[k]=dvi_buf[k]+y1-down1; -info(p)=y_here;goto found; -} - -@ @<Change buffered instruction to |z| or |x| and |goto found|@>= -{@+k=location(p)-dvi_offset; -if (k < 0) k=k+dvi_buf_size; -dvi_buf[k]=dvi_buf[k]+z1-down1; -info(p)=z_here;goto found; -} - -@ In case you are wondering when all the movement nodes are removed from -\TeX's memory, the answer is that they are recycled just before -|hlist_out| and |vlist_out| finish outputting a box. This restores the -down and right stacks to the state they were in before the box was output, -except that some |info|'s may have become more restrictive. - -@p static void prune_movements(int @!l) - /*delete movement nodes with |location >= l|*/ -{@+ -pointer p; /*node being deleted*/ -while (down_ptr!=null) - {@+if (location(down_ptr) < l) goto done; - p=down_ptr;down_ptr=link(p);free_node(p, movement_node_size); - } -done: while (right_ptr!=null) - {@+if (location(right_ptr) < l) return; - p=right_ptr;right_ptr=link(p);free_node(p, movement_node_size); - } -} - -@ The actual distances by which we want to move might be computed as the -sum of several separate movements. For example, there might be several -glue nodes in succession, or we might want to move right by the width of -some box plus some amount of glue. More importantly, the baselineskip -distances are computed in terms of glue together with the depth and -height of adjacent boxes, and we want the \.{DVI} file to lump these -three quantities together into a single motion. - -Therefore, \TeX\ maintains two pairs of global variables: |dvi_h| and |dvi_v| -are the |h| and |v| coordinates corresponding to the commands actually -output to the \.{DVI} file, while |cur_h| and |cur_v| are the coordinates -corresponding to the current state of the output routines. Coordinate -changes will accumulate in |cur_h| and |cur_v| without being reflected -in the output, until such a change becomes necessary or desirable; we -can call the |movement| procedure whenever we want to make |dvi_h==cur_h| -or |dvi_v==cur_v|. - -The current font reflected in the \.{DVI} output is called |dvi_f|; -there is no need for a `\\{cur\_f}' variable. - -The depth of nesting of |hlist_out| and |vlist_out| is called |cur_s|; -this is essentially the depth of |push| commands in the \.{DVI} output. - -@d synch_h if (cur_h!=dvi_h) - {@+movement(cur_h-dvi_h, right1);dvi_h=cur_h; - } -@d synch_v if (cur_v!=dvi_v) - {@+movement(cur_v-dvi_v, down1);dvi_v=cur_v; - } - -@<Glob...@>= -static scaled @!dvi_h, @!dvi_v; /*a \.{DVI} reader program thinks we are here*/ -static scaled @!cur_h, @!cur_v; /*\TeX\ thinks we are here*/ -static internal_font_number @!dvi_f; /*the current font*/ -static int @!cur_s; /*current depth of output box nesting, initially $-1$*/ - -@ @<Initialize variables as |ship_out| begins@>= -dvi_h=0;dvi_v=0;cur_h=h_offset;dvi_f=null_font; -ensure_dvi_open; -if (total_pages==0) - {@+dvi_out(pre);dvi_out(id_byte); /*output the preamble*/ -@^preamble of \.{DVI} file@> - dvi_four(25400000);dvi_four(473628672); /*conversion ratio for sp*/ - prepare_mag();dvi_four(mag); /*magnification factor is frozen*/ - old_setting=selector;selector=new_string; - print(" TeX output ");print_int(year);print_char('.'); - print_two(month);print_char('.');print_two(day); - print_char(':');print_two(time/60); - print_two(time%60); - selector=old_setting;dvi_out(cur_length); - for (s=str_start[str_ptr]; s<=pool_ptr-1; s++) dvi_out(so(str_pool[s])); - pool_ptr=str_start[str_ptr]; /*flush the current string*/ - } - -@ When |hlist_out| is called, its duty is to output the box represented -by the |hlist_node| pointed to by |temp_ptr|. The reference point of that -box has coordinates |(cur_h, cur_v)|. - -Similarly, when |vlist_out| is called, its duty is to output the box represented -by the |vlist_node| pointed to by |temp_ptr|. The reference point of that -box has coordinates |(cur_h, cur_v)|. -@^recursion@> - -@p static void vlist_out(void); /*|hlist_out| and |vlist_out| are mutually - recursive*/ - -@ The recursive procedures |hlist_out| and |vlist_out| each have local variables -|save_h| and |save_v| to hold the values of |dvi_h| and |dvi_v| just before -entering a new level of recursion. In effect, the values of |save_h| and -|save_v| on \TeX's run-time stack correspond to the values of |h| and |v| -that a \.{DVI}-reading program will push onto its coordinate stack. - -@p @t\4@>@<Declare procedures needed in |hlist_out|, |vlist_out|@>@t@>@/ -static void hlist_out(void) /*output an |hlist_node| box*/ -{@+ -scaled base_line; /*the baseline coordinate for this box*/ -scaled @!left_edge; /*the left coordinate for this box*/ -scaled @!save_h, @!save_v; /*what |dvi_h| and |dvi_v| should pop to*/ -pointer @!this_box; /*pointer to containing box*/ -glue_ord @!g_order; /*applicable order of infinity for glue*/ -int @!g_sign; /*selects type of glue*/ -pointer @!p; /*current position in the hlist*/ -int @!save_loc; /*\.{DVI} byte location upon entry*/ -pointer @!leader_box; /*the leader box being replicated*/ -scaled @!leader_wd; /*width of leader box being replicated*/ -scaled @!lx; /*extra space between leader boxes*/ -bool @!outer_doing_leaders; /*were we doing leaders?*/ -scaled @!edge; /*left edge of sub-box, or right edge of leader space*/ -double @!glue_temp; /*glue value before rounding*/ -double @!cur_glue; /*glue seen so far*/ -scaled @!cur_g; /*rounded equivalent of |cur_glue| times the glue ratio*/ -cur_g=0;cur_glue=float_constant(0); -this_box=temp_ptr;g_order=glue_order(this_box); -g_sign=glue_sign(this_box);p=list_ptr(this_box); -incr(cur_s); -if (cur_s > 0) dvi_out(push); -if (cur_s > max_push) max_push=cur_s; -save_loc=dvi_offset+dvi_ptr;base_line=cur_v;left_edge=cur_h; -while (p!=null) @<Output node |p| for |hlist_out| and move to the next node, maintaining -the condition |cur_v=base_line|@>; -prune_movements(save_loc); -if (cur_s > 0) dvi_pop(save_loc); -decr(cur_s); -} - -@ We ought to give special care to the efficiency of one part of |hlist_out|, -since it belongs to \TeX's inner loop. When a |char_node| is encountered, -we save a little time by processing several nodes in succession until -reaching a non-|char_node|. The program uses the fact that |set_char_0==0|. -@^inner loop@> - -@<Output node |p| for |hlist_out|...@>= -reswitch: if (is_char_node(p)) - {@+synch_h;synch_v; - @/do@+{f=font(p);c=character(p); - if (f!=dvi_f) @<Change font |dvi_f| to |f|@>; - if (c >= qi(128)) dvi_out(set1); - dvi_out(qo(c));@/ - cur_h=cur_h+char_width(f, char_info(f, c)); - p=link(p); - }@+ while (!(!is_char_node(p))); - dvi_h=cur_h; - } -else@<Output the non-|char_node| |p| for |hlist_out| and move to the next node@>@; - -@ @<Change font |dvi_f| to |f|@>= -{@+if (!font_used[f]) - {@+dvi_font_def(f);font_used[f]=true; - } -if (f <= 64+font_base) dvi_out(f-font_base-1+fnt_num_0)@; -else{@+dvi_out(fnt1);dvi_out(f-font_base-1); - } -dvi_f=f; -} - -@ @<Output the non-|char_node| |p| for |hlist_out|...@>= -{@+switch (type(p)) { -case hlist_node: case vlist_node: @<Output a box in an hlist@>@;@+break; -case rule_node: {@+rule_ht=height(p);rule_dp=depth(p);rule_wd=width(p); - goto fin_rule; - } -case whatsit_node: @<Output the whatsit node |p| in an hlist@>;@+break; -case glue_node: @<Move right or output leaders@>@; -case kern_node: case math_node: cur_h=cur_h+width(p);@+break; -case ligature_node: @<Make node |p| look like a |char_node| and |goto reswitch|@>@; -default:do_nothing; -} @/ -goto next_p; -fin_rule: @<Output a rule in an hlist@>; -move_past: cur_h=cur_h+rule_wd; -next_p: p=link(p); -} - -@ @<Output a box in an hlist@>= -if (list_ptr(p)==null) cur_h=cur_h+width(p); -else{@+save_h=dvi_h;save_v=dvi_v; - cur_v=base_line+shift_amount(p); /*shift the box down*/ - temp_ptr=p;edge=cur_h; - if (type(p)==vlist_node) vlist_out();@+else hlist_out(); - dvi_h=save_h;dvi_v=save_v; - cur_h=edge+width(p);cur_v=base_line; - } - -@ @<Output a rule in an hlist@>= -if (is_running(rule_ht)) rule_ht=height(this_box); -if (is_running(rule_dp)) rule_dp=depth(this_box); -rule_ht=rule_ht+rule_dp; /*this is the rule thickness*/ -if ((rule_ht > 0)&&(rule_wd > 0)) /*we don't output empty rules*/ - {@+synch_h;cur_v=base_line+rule_dp;synch_v; - dvi_out(set_rule);dvi_four(rule_ht);dvi_four(rule_wd); - cur_v=base_line;dvi_h=dvi_h+rule_wd; - } - -@ @d billion float_constant(1000000000) -@d vet_glue(A) glue_temp=A; - if (glue_temp > billion) - glue_temp=billion; - else if (glue_temp < -billion) - glue_temp=-billion - -@<Move right or output leaders@>= -{@+g=glue_ptr(p);rule_wd=width(g)-cur_g; -if (g_sign!=normal) - {@+if (g_sign==stretching) - {@+if (stretch_order(g)==g_order) - {@+cur_glue=cur_glue+stretch(g); - vet_glue(float(glue_set(this_box))*cur_glue); -@^real multiplication@> - cur_g=round(glue_temp); - } - } - else if (shrink_order(g)==g_order) - {@+cur_glue=cur_glue-shrink(g); - vet_glue(float(glue_set(this_box))*cur_glue); - cur_g=round(glue_temp); - } - } -rule_wd=rule_wd+cur_g; -if (subtype(p) >= a_leaders) - @<Output leaders in an hlist, |goto fin_rule| if a rule or to |next_p| if done@>; -goto move_past; -} - -@ @<Output leaders in an hlist...@>= -{@+leader_box=leader_ptr(p); -if (type(leader_box)==rule_node) - {@+rule_ht=height(leader_box);rule_dp=depth(leader_box); - goto fin_rule; - } -leader_wd=width(leader_box); -if ((leader_wd > 0)&&(rule_wd > 0)) - {@+rule_wd=rule_wd+10; /*compensate for floating-point rounding*/ - edge=cur_h+rule_wd;lx=0; - @<Let |cur_h| be the position of the first box, and set |leader_wd+lx| to the spacing -between corresponding parts of boxes@>; - while (cur_h+leader_wd <= edge) - @<Output a leader box at |cur_h|, then advance |cur_h| by |leader_wd+lx|@>; - cur_h=edge-10;goto next_p; - } -} - -@ The calculations related to leaders require a bit of care. First, in the -case of |a_leaders| (aligned leaders), we want to move |cur_h| to -|left_edge| plus the smallest multiple of |leader_wd| for which the result -is not less than the current value of |cur_h|; i.e., |cur_h| should become -$|left_edge|+|leader_wd|\times\lceil -(|cur_h|-|left_edge|)/|leader_wd|\rceil$. The program here should work in -all cases even though some implementations of \PASCAL\ give nonstandard -results for the |/| operation when |cur_h| is less than |left_edge|. - -In the case of |c_leaders| (centered leaders), we want to increase |cur_h| -by half of the excess space not occupied by the leaders; and in the -case of |x_leaders| (expanded leaders) we increase |cur_h| -by $1/(q+1)$ of this excess space, where $q$ is the number of times the -leader box will be replicated. Slight inaccuracies in the division might -accumulate; half of this rounding error is placed at each end of the leaders. - -@<Let |cur_h| be the position of the first box,...@>= -if (subtype(p)==a_leaders) - {@+save_h=cur_h; - cur_h=left_edge+leader_wd*((cur_h-left_edge)/leader_wd); - if (cur_h < save_h) cur_h=cur_h+leader_wd; - } -else{@+lq=rule_wd/leader_wd; /*the number of box copies*/ - lr=rule_wd%leader_wd; /*the remaining space*/ - if (subtype(p)==c_leaders) cur_h=cur_h+(lr/2); - else{@+lx=lr/(lq+1); - cur_h=cur_h+((lr-(lq-1)*lx)/2); - } - } - -@ The `\\{synch}' operations here are intended to decrease the number of -bytes needed to specify horizontal and vertical motion in the \.{DVI} output. - -@<Output a leader box at |cur_h|,...@>= -{@+cur_v=base_line+shift_amount(leader_box);synch_v;save_v=dvi_v;@/ -synch_h;save_h=dvi_h;temp_ptr=leader_box; -outer_doing_leaders=doing_leaders;doing_leaders=true; -if (type(leader_box)==vlist_node) vlist_out();@+else hlist_out(); -doing_leaders=outer_doing_leaders; -dvi_v=save_v;dvi_h=save_h;cur_v=base_line; -cur_h=save_h+leader_wd+lx; -} - -@ The |vlist_out| routine is similar to |hlist_out|, but a bit simpler. - -@p static void vlist_out(void) /*output a |vlist_node| box*/ -{@+ -scaled left_edge; /*the left coordinate for this box*/ -scaled @!top_edge; /*the top coordinate for this box*/ -scaled @!save_h, @!save_v; /*what |dvi_h| and |dvi_v| should pop to*/ -pointer @!this_box; /*pointer to containing box*/ -glue_ord @!g_order; /*applicable order of infinity for glue*/ -int @!g_sign; /*selects type of glue*/ -pointer @!p; /*current position in the vlist*/ -int @!save_loc; /*\.{DVI} byte location upon entry*/ -pointer @!leader_box; /*the leader box being replicated*/ -scaled @!leader_ht; /*height of leader box being replicated*/ -scaled @!lx; /*extra space between leader boxes*/ -bool @!outer_doing_leaders; /*were we doing leaders?*/ -scaled @!edge; /*bottom boundary of leader space*/ -double @!glue_temp; /*glue value before rounding*/ -double @!cur_glue; /*glue seen so far*/ -scaled @!cur_g; /*rounded equivalent of |cur_glue| times the glue ratio*/ -cur_g=0;cur_glue=float_constant(0); -this_box=temp_ptr;g_order=glue_order(this_box); -g_sign=glue_sign(this_box);p=list_ptr(this_box); -incr(cur_s); -if (cur_s > 0) dvi_out(push); -if (cur_s > max_push) max_push=cur_s; -save_loc=dvi_offset+dvi_ptr;left_edge=cur_h;cur_v=cur_v-height(this_box); -top_edge=cur_v; -while (p!=null) @<Output node |p| for |vlist_out| and move to the next node, maintaining -the condition |cur_h=left_edge|@>; -prune_movements(save_loc); -if (cur_s > 0) dvi_pop(save_loc); -decr(cur_s); -} - -@ @<Output node |p| for |vlist_out|...@>= -{@+if (is_char_node(p)) confusion("vlistout"); -@:this can't happen vlistout}{\quad vlistout@> -else@<Output the non-|char_node| |p| for |vlist_out|@>; -next_p: p=link(p); -} - -@ @<Output the non-|char_node| |p| for |vlist_out|@>= -{@+switch (type(p)) { -case hlist_node: case vlist_node: @<Output a box in a vlist@>@;@+break; -case rule_node: {@+rule_ht=height(p);rule_dp=depth(p);rule_wd=width(p); - goto fin_rule; - } -case whatsit_node: @<Output the whatsit node |p| in a vlist@>;@+break; -case glue_node: @<Move down or output leaders@>@; -case kern_node: cur_v=cur_v+width(p);@+break; -default:do_nothing; -} @/ -goto next_p; -fin_rule: @<Output a rule in a vlist, |goto next_p|@>; -move_past: cur_v=cur_v+rule_ht; -} - -@ The |synch_v| here allows the \.{DVI} output to use one-byte commands -for adjusting |v| in most cases, since the baselineskip distance will -usually be constant. - -@<Output a box in a vlist@>= -if (list_ptr(p)==null) cur_v=cur_v+height(p)+depth(p); -else{@+cur_v=cur_v+height(p);synch_v; - save_h=dvi_h;save_v=dvi_v; - cur_h=left_edge+shift_amount(p); /*shift the box right*/ - temp_ptr=p; - if (type(p)==vlist_node) vlist_out();@+else hlist_out(); - dvi_h=save_h;dvi_v=save_v; - cur_v=save_v+depth(p);cur_h=left_edge; - } - -@ @<Output a rule in a vlist...@>= -if (is_running(rule_wd)) rule_wd=width(this_box); -rule_ht=rule_ht+rule_dp; /*this is the rule thickness*/ -cur_v=cur_v+rule_ht; -if ((rule_ht > 0)&&(rule_wd > 0)) /*we don't output empty rules*/ - {@+synch_h;synch_v; - dvi_out(put_rule);dvi_four(rule_ht);dvi_four(rule_wd); - } -goto next_p - -@ @<Move down or output leaders@>= -{@+g=glue_ptr(p);rule_ht=width(g)-cur_g; -if (g_sign!=normal) - {@+if (g_sign==stretching) - {@+if (stretch_order(g)==g_order) - {@+cur_glue=cur_glue+stretch(g); - vet_glue(float(glue_set(this_box))*cur_glue); -@^real multiplication@> - cur_g=round(glue_temp); - } - } - else if (shrink_order(g)==g_order) - {@+cur_glue=cur_glue-shrink(g); - vet_glue(float(glue_set(this_box))*cur_glue); - cur_g=round(glue_temp); - } - } -rule_ht=rule_ht+cur_g; -if (subtype(p) >= a_leaders) - @<Output leaders in a vlist, |goto fin_rule| if a rule or to |next_p| if done@>; -goto move_past; -} - -@ @<Output leaders in a vlist...@>= -{@+leader_box=leader_ptr(p); -if (type(leader_box)==rule_node) - {@+rule_wd=width(leader_box);rule_dp=0; - goto fin_rule; - } -leader_ht=height(leader_box)+depth(leader_box); -if ((leader_ht > 0)&&(rule_ht > 0)) - {@+rule_ht=rule_ht+10; /*compensate for floating-point rounding*/ - edge=cur_v+rule_ht;lx=0; - @<Let |cur_v| be the position of the first box, and set |leader_ht+lx| to the spacing -between corresponding parts of boxes@>; - while (cur_v+leader_ht <= edge) - @<Output a leader box at |cur_v|, then advance |cur_v| by |leader_ht+lx|@>; - cur_v=edge-10;goto next_p; - } -} - -@ @<Let |cur_v| be the position of the first box,...@>= -if (subtype(p)==a_leaders) - {@+save_v=cur_v; - cur_v=top_edge+leader_ht*((cur_v-top_edge)/leader_ht); - if (cur_v < save_v) cur_v=cur_v+leader_ht; - } -else{@+lq=rule_ht/leader_ht; /*the number of box copies*/ - lr=rule_ht%leader_ht; /*the remaining space*/ - if (subtype(p)==c_leaders) cur_v=cur_v+(lr/2); - else{@+lx=lr/(lq+1); - cur_v=cur_v+((lr-(lq-1)*lx)/2); - } - } - -@ When we reach this part of the program, |cur_v| indicates the top of a -leader box, not its baseline. - -@<Output a leader box at |cur_v|,...@>= -{@+cur_h=left_edge+shift_amount(leader_box);synch_h;save_h=dvi_h;@/ -cur_v=cur_v+height(leader_box);synch_v;save_v=dvi_v; -temp_ptr=leader_box; -outer_doing_leaders=doing_leaders;doing_leaders=true; -if (type(leader_box)==vlist_node) vlist_out();@+else hlist_out(); -doing_leaders=outer_doing_leaders; -dvi_v=save_v;dvi_h=save_h;cur_h=left_edge; -cur_v=save_v-height(leader_box)+leader_ht+lx; -} - -@ The |hlist_out| and |vlist_out| procedures are now complete, so we are -ready for the |ship_out| routine that gets them started in the first place. - -@p void ship_out(pointer @!p) /*output the box |p|*/ -{@+ -execute_output(p); -flush_node_list(p); -} - -@ @<Flush the box from memory, showing statistics if requested@>= -#ifdef @!STAT -if (tracing_stats > 1) - {@+print_nl("Memory usage before: "); -@.Memory usage...@> - print_int(var_used);print_char('&'); - print_int(dyn_used);print_char(';'); - } -#endif -flush_node_list(p); -#ifdef @!STAT -if (tracing_stats > 1) - {@+print(" after: "); - print_int(var_used);print_char('&'); - print_int(dyn_used);print("; still untouched: "); - print_int(hi_mem_min-lo_mem_max-1);print_ln(); - } -#endif - -@ @<Ship box |p| out@>= -@<Update the values of |max_h| and |max_v|; but if the page is too large, |goto done|@>; -@<Initialize variables as |ship_out| begins@>; -page_loc=dvi_offset+dvi_ptr; -dvi_out(bop); -for (k=0; k<=9; k++) dvi_four(count(k)); -dvi_four(last_bop);last_bop=page_loc; -cur_v=height(p)+v_offset;temp_ptr=p; -if (type(p)==vlist_node) vlist_out();@+else hlist_out(); -dvi_out(eop);incr(total_pages);cur_s=-1; -done: - -@ Sometimes the user will generate a huge page because other error messages -are being ignored. Such pages are not output to the \.{dvi} file, since they -may confuse the printing software. - -@<Update the values of |max_h| and |max_v|; but if the page is too large...@>= -if ((height(p) > max_dimen)||@|(depth(p) > max_dimen)||@| - (height(p)+depth(p)+v_offset > max_dimen)||@| - (width(p)+h_offset > max_dimen)) - {@+print_err("Huge page cannot be shipped out"); -@.Huge page...@> - help2("The page just created is more than 18 feet tall or",@/ - "more than 18 feet wide, so I suspect something went wrong."); - error(); - if (tracing_output <= 0) - {@+begin_diagnostic(); - print_nl("The following box has been deleted:"); -@.The following...deleted@> - show_box(p); - end_diagnostic(true); - } - goto done; - } -if (height(p)+depth(p)+v_offset > max_v) max_v=height(p)+depth(p)+v_offset; -if (width(p)+h_offset > max_h) max_h=width(p)+h_offset - -@ At the end of the program, we must finish things off by writing the -post\-amble. If |total_pages==0|, the \.{DVI} file was never opened. -If |total_pages >= 65536|, the \.{DVI} file will lie. And if -|max_push >= 65536|, the user deserves whatever chaos might ensue. - -An integer variable |k| will be declared for use by this routine. - -@<Finish the \.{DVI} file@>= -while (cur_s > -1) - {@+if (cur_s > 0) dvi_out(pop)@; - else{@+dvi_out(eop);incr(total_pages); - } - decr(cur_s); - } -if (total_pages==0) print_nl("No pages of output."); -@.No pages of output@> -else{@+dvi_out(post); /*beginning of the postamble*/ - dvi_four(last_bop);last_bop=dvi_offset+dvi_ptr-5; /*|post| location*/ - dvi_four(25400000);dvi_four(473628672); /*conversion ratio for sp*/ - prepare_mag();dvi_four(mag); /*magnification factor*/ - dvi_four(max_v);dvi_four(max_h);@/ - dvi_out(max_push/256);dvi_out(max_push%256);@/ - dvi_out((total_pages/256)%256);dvi_out(total_pages%256);@/ - @<Output the font definitions for all fonts that were used@>; - dvi_out(post_post);dvi_four(last_bop);dvi_out(id_byte);@/ - k=4+((dvi_buf_size-dvi_ptr)%4); /*the number of 223's*/ - while (k > 0) - {@+dvi_out(223);decr(k); - } - @<Empty the last bytes out of |dvi_buf|@>; - print_nl("Output written on ");slow_print(output_file_name); -@.Output written on x@> - print(" (");print_int(total_pages);print(" page"); - if (total_pages!=1) print_char('s'); - print(", ");print_int(dvi_offset+dvi_ptr);print(" bytes)."); - b_close(&dvi_file); - } - -@ @<Output the font definitions...@>= -while (font_ptr > font_base) - {@+if (font_used[font_ptr]) dvi_font_def(font_ptr); - decr(font_ptr); - } - -@* Packaging. -We're essentially done with the parts of \TeX\ that are concerned with -the input (|get_next|) and the output (|ship_out|). So it's time to -get heavily into the remaining part, which does the real work of typesetting. - -After lists are constructed, \TeX\ wraps them up and puts them into boxes. -Two major subroutines are given the responsibility for this task: |hpack| -applies to horizontal lists (hlists) and |vpack| applies to vertical lists -(vlists). The main duty of |hpack| and |vpack| is to compute the dimensions -of the resulting boxes, and to adjust the glue if one of those dimensions -is pre-specified. The computed sizes normally enclose all of the material -inside the new box; but some items may stick out if negative glue is used, -if the box is overfull, or if a \.{\\vbox} includes other boxes that have -been shifted left. - -The subroutine call |hpack(p, w, m)| returns a pointer to an |hlist_node| -for a box containing the hlist that starts at |p|. Parameter |w| specifies -a width; and parameter |m| is either `|exactly|' or `|additional|'. Thus, -|hpack(p, w, exactly)| produces a box whose width is exactly |w|, while -|hpack(p, w, additional)| yields a box whose width is the natural width plus -|w|. It is convenient to define a macro called `|natural|' to cover the -most common case, so that we can say |hpack(p, natural)| to get a box that -has the natural width of list |p|. - -Similarly, |vpack(p, w, m)| returns a pointer to a |vlist_node| for a -box containing the vlist that starts at |p|. In this case |w| represents -a height instead of a width; the parameter |m| is interpreted as in |hpack|. - -@d exactly 0 /*a box dimension is pre-specified*/ -@d additional 1 /*a box dimension is increased from the natural one*/ -@d natural 0, 0, 0, additional /*shorthand for parameters to |hpack| and |vpack|*/ - -@ The parameters to |hpack| and |vpack| correspond to \TeX's primitives -like `\.{\\hbox} \.{to} \.{300pt}', `\.{\\hbox} \.{spread} \.{10pt}'; note -that `\.{\\hbox}' with no dimension following it is equivalent to -`\.{\\hbox} \.{spread} \.{0pt}'. The |scan_spec| subroutine scans such -constructions in the user's input, including the mandatory left brace that -follows them, and it puts the specification onto |save_stack| so that the -desired box can later be obtained by executing the following code: -$$\vbox{\halign{#\hfil\cr -|save_ptr=save_ptr-2;|\cr -|hpack(p, saved(1), saved(0)).|\cr}}$$ -Special care is necessary to ensure that the special |save_stack| codes -are placed just below the new group code, because scanning can change -|save_stack| when \.{\\csname} appears. - -@p static void scan_spec(group_code @!c, bool @!three_codes) - /*scans a box specification and left brace*/ -{@+ -int @!s; /*temporarily saved value*/ -int @!spec_code; -if (three_codes) s=saved(0); -if (scan_keyword("to")) spec_code=exactly; -@.to@> -else if (scan_keyword("spread")) spec_code=additional; -@.spread@> -else{@+spec_code=additional;cur_val=cur_hfactor=cur_vfactor=0; - goto found; - } -scan_normal_dimen; -found: if (three_codes) - {@+saved(0)=s;incr(save_ptr); - } -saved(0)=spec_code;saved(1)=cur_val; -saved_hfactor(1)=cur_hfactor; -saved_vfactor(1)=cur_vfactor; -save_ptr=save_ptr+2; -new_save_level(c);scan_left_brace(); -} - -@ To figure out the glue setting, |hpack| and |vpack| determine how much -stretchability and shrinkability are present, considering all four orders -of infinity. The highest order of infinity that has a nonzero coefficient -is then used as if no other orders were present. - -For example, suppose that the given list contains six glue nodes with -the respective stretchabilities 3pt, 8fill, 5fil, 6pt, $-3$fil, $-8$fill. -Then the total is essentially 2fil; and if a total additional space of 6pt -is to be achieved by stretching, the actual amounts of stretch will be -0pt, 0pt, 15pt, 0pt, $-9$pt, and 0pt, since only `fil' glue will be -considered. (The `fill' glue is therefore not really stretching infinitely -with respect to `fil'; nobody would actually want that to happen.) - -The arrays |total_stretch| and |total_shrink| are used to determine how much -glue of each kind is present. A global variable |last_badness| is used -to implement \.{\\badness}. - -@<Glob...@>= -scaled @!total_stretch0[filll-normal+1], *const @!total_stretch = @!total_stretch0-normal, @!total_shrink0[filll-normal+1], *const @!total_shrink = @!total_shrink0-normal; - /*glue found by |hpack| or |vpack|*/ -int @!last_badness; /*badness of the most recently packaged box*/ - -@ If the global variable |adjust_tail| is non-null, the |hpack| routine -also removes all occurrences of |ins_node|, |mark_node|, and |adjust_node| -items and appends the resulting material onto the list that ends at -location |adjust_tail|. - -@<Glob...@>= -pointer @!adjust_tail; /*tail of adjustment list*/ - -@ @<Set init...@>=adjust_tail=null;last_badness=0; - -@ Here now is |hpack|, which contains few if any surprises. - -@p extern pointer hpack(pointer p, scaled w, scaled hf, scaled vf, small_number m); - -@ @<Clear dimensions to zero@>= -d=0;x=0; -total_stretch[normal]=0;total_shrink[normal]=0; -total_stretch[fil]=0;total_shrink[fil]=0; -total_stretch[fill]=0;total_shrink[fill]=0; -total_stretch[filll]=0;total_shrink[filll]=0 - -@ @<Examine node |p| in the hlist, taking account of its effect...@>= -@^inner loop@> -{@+reswitch: while (is_char_node(p)) - @<Incorporate character dimensions into the dimensions of the hbox that will contain~it, -then move to the next node@>; -if (p!=null) - {@+switch (type(p)) { - case hlist_node: case vlist_node: case rule_node: case unset_node: case unset_set_node: case unset_pack_node: - @<Incorporate box dimensions into the dimensions of the hbox that will contain~it@>@;@+break; - case ins_node: case mark_node: case adjust_node: if (adjust_tail!=null) - @<Transfer node |p| to the adjustment list@>@;@+break; - case whatsit_node: @<Incorporate a whatsit node into an hbox@>;@+break; - case glue_node: @<Incorporate glue into the horizontal totals@>@;@+break; - case kern_node: case math_node: x=x+width(p);@+break; - case ligature_node: @<Make node |p| look like a |char_node| and |goto reswitch|@>@; - default:do_nothing; - } @/ - p=link(p); - } -} - - -@ @<Make node |p| look like a |char_node| and |goto reswitch|@>= -{@+mem[lig_trick]=mem[lig_char(p)];link(lig_trick)=link(p); -p=lig_trick;goto reswitch; -} - -@ The code here implicitly uses the fact that running dimensions are -indicated by |null_flag|, which will be ignored in the calculations -because it is a highly negative number. - -@<Incorporate box dimensions into the dimensions of the hbox...@>= -{@+x=x+width(p); -if (type(p) >= rule_node) s=0;@+else s=shift_amount(p); -if (height(p)-s > h) h=height(p)-s; -if (depth(p)+s > d) d=depth(p)+s; -} - -@ The following code is part of \TeX's inner loop; i.e., adding another -character of text to the user's input will cause each of these instructions -to be exercised one more time. -@^inner loop@> - -@<Incorporate character dimensions into the dimensions of the hbox...@>= -{@+f=font(p);i=char_info(f, character(p));hd=height_depth(i); -x=x+char_width(f, i);@/ -s=char_height(f, hd);@+if (s > h) h=s; -s=char_depth(f, hd);@+if (s > d) d=s; -p=link(p); -} - -@ Although node |q| is not necessarily the immediate predecessor of node |p|, -it always points to some node in the list preceding |p|. Thus, we can delete -nodes by moving |q| when necessary. The algorithm takes linear time, and the -extra computation does not intrude on the inner loop unless it is necessary -to make a deletion. -@^inner loop@> - -@<Transfer node |p| to the adjustment list@>= -{@+while (link(q)!=p) q=link(q); -if (type(p)==adjust_node) - {@+link(adjust_tail)=adjust_ptr(p); - while (link(adjust_tail)!=null) adjust_tail=link(adjust_tail); - p=link(p);free_node(link(q), small_node_size); - } -else{@+link(adjust_tail)=p;adjust_tail=p;p=link(p); - } -link(q)=p;p=q; -} - -@ @<Incorporate glue into the horizontal totals@>= -{@+g=glue_ptr(p);x=x+width(g);@/ -o=stretch_order(g);total_stretch[o]=total_stretch[o]+stretch(g); -o=shrink_order(g);total_shrink[o]=total_shrink[o]+shrink(g); -if (subtype(p) >= a_leaders) - {@+g=leader_ptr(p); - if (height(g) > h) h=height(g); - if (depth(g) > d) d=depth(g); - } -} - -@ When we get to the present part of the program, |x| is the natural width -of the box being packaged. - -@<Determine the value of |width(r)| and the appropriate glue setting...@>= -if (m==additional) w=x+w; -width(r)=w;x=w-x; /*now |x| is the excess to be made up*/ -if (x==0) - {@+glue_sign(r)=normal;glue_order(r)=normal; - set_glue_ratio_zero(glue_set(r)); - goto end; - } -else if (x > 0) @<Determine horizontal glue stretch setting, then |return| or \hbox{|goto -common_ending|}@>@; -else@<Determine horizontal glue shrink setting, then |return| or \hbox{|goto common_ending|}@>@; - -@ @<Determine horizontal glue stretch setting...@>= -{@+@<Determine the stretch order@>; -glue_order(r)=o;glue_sign(r)=stretching; -if (total_stretch[o]!=0) glue_set(r)=unfloat(x/(double)total_stretch[o]); -@^real division@> -else{@+glue_sign(r)=normal; - set_glue_ratio_zero(glue_set(r)); /*there's nothing to stretch*/ - } -if (o==normal) if (list_ptr(r)!=null) - @<Report an underfull hbox and |goto common_ending|, if this box is sufficiently -bad@>; -goto end; -} - -@ @<Determine the stretch order@>= -if (total_stretch[filll]!=0) o=filll; -else if (total_stretch[fill]!=0) o=fill; -else if (total_stretch[fil]!=0) o=fil; -else o=normal - -@ @<Report an underfull hbox and |goto common_ending|, if...@>= -{@+last_badness=badness(x, total_stretch[normal]); -if (last_badness > hbadness) - {@+print_ln(); - if (last_badness > 100) print_nl("Underfull");@+else print_nl("Loose"); - print(" \\hbox (badness ");print_int(last_badness); -@.Underfull \\hbox...@> -@.Loose \\hbox...@> - goto common_ending; - } -} - -@ In order to provide a decent indication of where an overfull or underfull -box originated, we use a global variable |pack_begin_line| that is -set nonzero only when |hpack| is being called by the paragraph builder -or the alignment finishing routine. - -@<Glob...@>= -int @!pack_begin_line; /*source file line where the current paragraph - or alignment began; a negative value denotes alignment*/ - -@ @<Set init...@>= -pack_begin_line=0; - -@ @<Finish issuing a diagnostic message for an overfull or underfull hbox@>= -if (output_active) print(") has occurred while \\output is active"); -else{@+if (pack_begin_line!=0) - {@+if (pack_begin_line > 0) print(") in paragraph at lines "); - else print(") in alignment at lines "); - print_int(abs(pack_begin_line)); - print("--"); - } - else print(") detected at line "); - print_int(line); - } -print_ln();@/ -font_in_short_display=null_font;short_display(list_ptr(r));print_ln();@/ -begin_diagnostic();show_box(r);end_diagnostic(true) - -@ @<Determine horizontal glue shrink setting...@>= -{@+@<Determine the shrink order@>; -glue_order(r)=o;glue_sign(r)=shrinking; -if (total_shrink[o]!=0) glue_set(r)=unfloat((-x)/(double)total_shrink[o]); -@^real division@> -else{@+glue_sign(r)=normal; - set_glue_ratio_zero(glue_set(r)); /*there's nothing to shrink*/ - } -if ((total_shrink[o] < -x)&&(o==normal)&&(list_ptr(r)!=null)) - {@+last_badness=1000000; - set_glue_ratio_one(glue_set(r)); /*use the maximum shrinkage*/ - @<Report an overfull hbox and |goto common_ending|, if this box is sufficiently -bad@>; - } -else if (o==normal) if (list_ptr(r)!=null) - @<Report a tight hbox and |goto common_ending|, if this box is sufficiently bad@>; -goto end; -} - -@ @<Determine the shrink order@>= -if (total_shrink[filll]!=0) o=filll; -else if (total_shrink[fill]!=0) o=fill; -else if (total_shrink[fil]!=0) o=fil; -else o=normal - -@ @<Report an overfull hbox and |goto common_ending|, if...@>= -if ((-x-total_shrink[normal] > hfuzz)||(hbadness < 100)) - {@+if ((overfull_rule > 0)&&(-x-total_shrink[normal] > hfuzz)) - {@+while (link(q)!=null) q=link(q); - link(q)=new_rule(); - width(link(q))=overfull_rule; - } - print_ln();print_nl("Overfull \\hbox ("); -@.Overfull \\hbox...@> - print_scaled(-x-total_shrink[normal]);print("pt too wide"); - goto common_ending; - } - -@ @<Report a tight hbox and |goto common_ending|, if...@>= -{@+last_badness=badness(-x, total_shrink[normal]); -if (last_badness > hbadness) - {@+print_ln();print_nl("Tight \\hbox (badness ");print_int(last_badness); -@.Tight \\hbox...@> - goto common_ending; - } -} - -@ The |vpack| subroutine is actually a special case of a slightly more -general routine called |vpackage|, which has four parameters. The fourth -parameter, which is |max_dimen| in the case of |vpack|, specifies the -maximum depth of the page box that is constructed. The depth is first -computed by the normal rules; if it exceeds this limit, the reference -point is simply moved down until the limiting depth is attained. - - -@p -#define vpack(...) @[vpackage(__VA_ARGS__, max_dimen)@] /*special case of unconstrained depth*/ -extern pointer vpackage(pointer p, scaled h, scaled hf, scaled vf, small_number m, scaled l); - -@ @<Examine node |p| in the vlist, taking account of its effect...@>= -{@+if (is_char_node(p)) confusion("vpack"); -@:this can't happen vpack}{\quad vpack@> -else switch (type(p)) { - case hlist_node: case vlist_node: case rule_node: case unset_node: case unset_set_node: case unset_pack_node: - @<Incorporate box dimensions into the dimensions of the vbox that will contain~it@>@;@+break; - case whatsit_node: @<Incorporate a whatsit node into a vbox@>;@+break; - case glue_node: @<Incorporate glue into the vertical totals@>@;@+break; - case kern_node: {@+x=x+d+width(p);d=0; - } @+break; - default:do_nothing; - } -p=link(p); -} - -@ @<Incorporate box dimensions into the dimensions of the vbox...@>= -{@+x=x+d+height(p);d=depth(p); -if (type(p) >= rule_node) s=0;@+else s=shift_amount(p); -if (width(p)+s > w) w=width(p)+s; -} - -@ @<Incorporate glue into the vertical totals@>= -{@+x=x+d;d=0;@/ -g=glue_ptr(p);x=x+width(g);@/ -o=stretch_order(g);total_stretch[o]=total_stretch[o]+stretch(g); -o=shrink_order(g);total_shrink[o]=total_shrink[o]+shrink(g); -if (subtype(p) >= a_leaders) - {@+g=leader_ptr(p); - if (width(g) > w) w=width(g); - } -} - -@ When we get to the present part of the program, |x| is the natural height -of the box being packaged. - -@<Determine the value of |height(r)| and the appropriate glue setting...@>= -if (m==additional) h=x+h; -height(r)=h;x=h-x; /*now |x| is the excess to be made up*/ -if (x==0) - {@+glue_sign(r)=normal;glue_order(r)=normal; - set_glue_ratio_zero(glue_set(r)); - goto end; - } -else if (x > 0) @<Determine vertical glue stretch setting, then |return| or \hbox{|goto -common_ending|}@>@; -else@<Determine vertical glue shrink setting, then |return| or \hbox{|goto common_ending|}@>@; - -@ @<Determine vertical glue stretch setting...@>= -{@+@<Determine the stretch order@>; -glue_order(r)=o;glue_sign(r)=stretching; -if (total_stretch[o]!=0) glue_set(r)=unfloat(x/(double)total_stretch[o]); -@^real division@> -else{@+glue_sign(r)=normal; - set_glue_ratio_zero(glue_set(r)); /*there's nothing to stretch*/ - } -if (o==normal) if (list_ptr(r)!=null) - @<Report an underfull vbox and |goto common_ending|, if this box is sufficiently -bad@>; -goto end; -} - -@ @<Report an underfull vbox and |goto common_ending|, if...@>= -{@+last_badness=badness(x, total_stretch[normal]); -if (last_badness > vbadness) - {@+print_ln(); - if (last_badness > 100) print_nl("Underfull");@+else print_nl("Loose"); - print(" \\vbox (badness ");print_int(last_badness); -@.Underfull \\vbox...@> -@.Loose \\vbox...@> - goto common_ending; - } -} - -@ @<Finish issuing a diagnostic message for an overfull or underfull vbox@>= -if (output_active) print(") has occurred while \\output is active"); -else{@+if (pack_begin_line!=0) /*it's actually negative*/ - {@+print(") in alignment at lines "); - print_int(abs(pack_begin_line)); - print("--"); - } - else print(") detected at line "); - print_int(line); - print_ln();@/ - } -begin_diagnostic();show_box(r);end_diagnostic(true) - -@ @<Determine vertical glue shrink setting...@>= -{@+@<Determine the shrink order@>; -glue_order(r)=o;glue_sign(r)=shrinking; -if (total_shrink[o]!=0) glue_set(r)=unfloat((-x)/(double)total_shrink[o]); -@^real division@> -else{@+glue_sign(r)=normal; - set_glue_ratio_zero(glue_set(r)); /*there's nothing to shrink*/ - } -if ((total_shrink[o] < -x)&&(o==normal)&&(list_ptr(r)!=null)) - {@+last_badness=1000000; - set_glue_ratio_one(glue_set(r)); /*use the maximum shrinkage*/ - @<Report an overfull vbox and |goto common_ending|, if this box is sufficiently -bad@>; - } -else if (o==normal) if (list_ptr(r)!=null) - @<Report a tight vbox and |goto common_ending|, if this box is sufficiently bad@>; -goto end; -} - -@ @<Report an overfull vbox and |goto common_ending|, if...@>= -if ((-x-total_shrink[normal] > vfuzz)||(vbadness < 100)) - {@+print_ln();print_nl("Overfull \\vbox ("); -@.Overfull \\vbox...@> - print_scaled(-x-total_shrink[normal]);print("pt too high"); - goto common_ending; - } - -@ @<Report a tight vbox and |goto common_ending|, if...@>= -{@+last_badness=badness(-x, total_shrink[normal]); -if (last_badness > vbadness) - {@+print_ln();print_nl("Tight \\vbox (badness ");print_int(last_badness); -@.Tight \\vbox...@> - goto common_ending; - } -} - -@ When a box is being appended to the current vertical list, the -baselineskip calculation is handled by the |append_to_vlist| routine. - -@p void append_to_vlist(pointer @!b)@t\2\2@>@/ -{ bool height_known;@t\1@>@/ - height_known=(type(b)==hlist_node || type(b)==vlist_node ||@| - (type(b)==whatsit_node && subtype(b)==hset_node) ||@| - (type(b)==whatsit_node && subtype(b)==image_node));@/ - if (prev_depth > ignore_depth && height_known)@/ - {@+scaled d;@t\1@> /*deficiency of space between baselines*/ - pointer @!p; /*a new glue node*/ - {@+d=width(baseline_skip)-prev_depth-height(b); - if (d < line_skip_limit) p=new_param_glue(line_skip_code); - else{@+p=new_skip_param(baseline_skip_code); - width(temp_ptr)=d; /*|temp_ptr==glue_ptr(p)|*/ - } - link(tail)=p;tail=p; - }@+ -} @+ else @+if (prev_depth<=unknown_depth || prev_depth>ignore_depth )@t\2@>@/ - {@+pointer p; - p=new_baseline_node(baseline_skip, line_skip, line_skip_limit); - link(tail)= p;tail= p; - } - link(tail)=b;tail=b; - if (height_known) - prev_depth=depth(b); /* then also depth is known */ - else - prev_depth=unknown_depth; -} - -@* Data structures for math mode. -When \TeX\ reads a formula that is enclosed between \.\$'s, it constructs an -{\sl mlist}, which is essentially a tree structure representing that -formula. An mlist is a linear sequence of items, but we can regard it as -a tree structure because mlists can appear within mlists. For example, many -of the entries can be subscripted or superscripted, and such ``scripts'' -are mlists in their own right. - -An entire formula is parsed into such a tree before any of the actual -typesetting is done, because the current style of type is usually not -known until the formula has been fully scanned. For example, when the -formula `\.{\$a+b \\over c+d\$}' is being read, there is no way to tell -that `\.{a+b}' will be in script size until `\.{\\over}' has appeared. - -During the scanning process, each element of the mlist being built is -classified as a relation, a binary operator, an open parenthesis, etc., -or as a construct like `\.{\\sqrt}' that must be built up. This classification -appears in the mlist data structure. - -After a formula has been fully scanned, the mlist is converted to an hlist -so that it can be incorporated into the surrounding text. This conversion is -controlled by a recursive procedure that decides all of the appropriate -styles by a ``top-down'' process starting at the outermost level and working -in towards the subformulas. The formula is ultimately pasted together using -combinations of horizontal and vertical boxes, with glue and penalty nodes -inserted as necessary. - -An mlist is represented internally as a linked list consisting chiefly -of ``noads'' (pronounced ``no-adds''), to distinguish them from the somewhat -similar ``nodes'' in hlists and vlists. Certain kinds of ordinary nodes are -allowed to appear in mlists together with the noads; \TeX\ tells the difference -by means of the |type| field, since a noad's |type| is always greater than -that of a node. An mlist does not contain character nodes, hlist nodes, vlist -nodes, math nodes, ligature nodes, -or unset nodes; in particular, each mlist item appears in the -variable-size part of |mem|, so the |type| field is always present. - -@ Each noad is four or more words long. The first word contains the |type| -and |subtype| and |link| fields that are already so familiar to us; the -second, third, and fourth words are called the noad's |nucleus|, |subscr|, -and |supscr| fields. - -Consider, for example, the simple formula `\.{\$x\^2\$}', which would be -parsed into an mlist containing a single element called an |ord_noad|. -The |nucleus| of this noad is a representation of `\.x', the |subscr| is -empty, and the |supscr| is a representation of `\.2'. - -The |nucleus|, |subscr|, and |supscr| fields are further broken into -subfields. If |p| points to a noad, and if |q| is one of its principal -fields (e.g., |q==subscr(p)|), there are several possibilities for the -subfields, depending on the |math_type| of |q|. - -\yskip\hang|math_type(q)==math_char| means that |fam(q)| refers to one of -the sixteen font families, and |character(q)| is the number of a character -within a font of that family, as in a character node. - -\yskip\hang|math_type(q)==math_text_char| is similar, but the character is -unsubscripted and unsuperscripted and it is followed immediately by another -character from the same font. (This |math_type| setting appears only -briefly during the processing; it is used to suppress unwanted italic -corrections.) - -\yskip\hang|math_type(q)==empty| indicates a field with no value (the -corresponding attribute of noad |p| is not present). - -\yskip\hang|math_type(q)==sub_box| means that |info(q)| points to a box -node (either an |hlist_node| or a |vlist_node|) that should be used as the -value of the field. The |shift_amount| in the subsidiary box node is the -amount by which that box will be shifted downward. - -\yskip\hang|math_type(q)==sub_mlist| means that |info(q)| points to -an mlist; the mlist must be converted to an hlist in order to obtain -the value of this field. - -\yskip\noindent In the latter case, we might have |info(q)==null|. This -is not the same as |math_type(q)==empty|; for example, `\.{\$P\_\{\}\$}' -and `\.{\$P\$}' produce different results (the former will not have the -``italic correction'' added to the width of |P|, but the ``script skip'' -will be added). - -The definitions of subfields given here are evidently wasteful of space, -since a halfword is being used for the |math_type| although only three -bits would be needed. However, there are hardly ever many noads present at -once, since they are soon converted to nodes that take up even more space, -so we can afford to represent them in whatever way simplifies the -programming. - -@d noad_size 4 /*number of words in a normal noad*/ -@d nucleus(A) A+1 /*the |nucleus| field of a noad*/ -@d supscr(A) A+2 /*the |supscr| field of a noad*/ -@d subscr(A) A+3 /*the |subscr| field of a noad*/ -@d math_type(A) link(A) /*a |halfword| in |mem|*/ -@d fam font /*a |quarterword| in |mem|*/ -@d math_char 1 /*|math_type| when the attribute is simple*/ -@d sub_box 2 /*|math_type| when the attribute is a box*/ -@d sub_mlist 3 /*|math_type| when the attribute is a formula*/ -@d math_text_char 4 /*|math_type| when italic correction is dubious*/ - -@ Each portion of a formula is classified as Ord, Op, Bin, Rel, Open, -Close, Punct, or Inner, for purposes of spacing and line breaking. An -|ord_noad|, |op_noad|, |bin_noad|, |rel_noad|, |open_noad|, |close_noad|, -|punct_noad|, or |inner_noad| is used to represent portions of the various -types. For example, an `\.=' sign in a formula leads to the creation of a -|rel_noad| whose |nucleus| field is a representation of an equals sign -(usually |fam==0|, |character==075|). A formula preceded by \.{\\mathrel} -also results in a |rel_noad|. When a |rel_noad| is followed by an -|op_noad|, say, and possibly separated by one or more ordinary nodes (not -noads), \TeX\ will insert a penalty node (with the current |rel_penalty|) -just after the formula that corresponds to the |rel_noad|, unless there -already was a penalty immediately following; and a ``thick space'' will be -inserted just before the formula that corresponds to the |op_noad|. - -A noad of type |ord_noad|, |op_noad|, \dots, |inner_noad| usually -has a |subtype==normal|. The only exception is that an |op_noad| might -have |subtype==limits| or |no_limits|, if the normal positioning of -limits has been overridden for this operator. - -@d ord_noad (unset_node+3) /*|type| of a noad classified Ord*/ -@d op_noad (ord_noad+1) /*|type| of a noad classified Op*/ -@d bin_noad (ord_noad+2) /*|type| of a noad classified Bin*/ -@d rel_noad (ord_noad+3) /*|type| of a noad classified Rel*/ -@d open_noad (ord_noad+4) /*|type| of a noad classified Open*/ -@d close_noad (ord_noad+5) /*|type| of a noad classified Close*/ -@d punct_noad (ord_noad+6) /*|type| of a noad classified Punct*/ -@d inner_noad (ord_noad+7) /*|type| of a noad classified Inner*/ -@d limits 1 /*|subtype| of |op_noad| whose scripts are to be above, below*/ -@d no_limits 2 /*|subtype| of |op_noad| whose scripts are to be normal*/ - -@ A |radical_noad| is five words long; the fifth word is the |left_delimiter| -field, which usually represents a square root sign. - -A |fraction_noad| is six words long; it has a |right_delimiter| field -as well as a |left_delimiter|. - -Delimiter fields are of type |four_quarters|, and they have four subfields -called |small_fam|, |small_char|, |large_fam|, |large_char|. These subfields -represent variable-size delimiters by giving the ``small'' and ``large'' -starting characters, as explained in Chapter~17 of {\sl The \TeX book}. -@:TeXbook}{\sl The \TeX book@> - -A |fraction_noad| is actually quite different from all other noads. Not -only does it have six words, it has |thickness|, |denominator|, and -|numerator| fields instead of |nucleus|, |subscr|, and |supscr|. The -|thickness| is a scaled value that tells how thick to make a fraction -rule; however, the special value |default_code| is used to stand for the -|default_rule_thickness| of the current size. The |numerator| and -|denominator| point to mlists that define a fraction; we always have -$$\hbox{|math_type(numerator)==math_type(denominator)==sub_mlist|}.$$ The -|left_delimiter| and |right_delimiter| fields specify delimiters that will -be placed at the left and right of the fraction. In this way, a -|fraction_noad| is able to represent all of \TeX's operators \.{\\over}, -\.{\\atop}, \.{\\above}, \.{\\overwithdelims}, \.{\\atopwithdelims}, and - \.{\\abovewithdelims}. - -@d left_delimiter(A) A+4 /*first delimiter field of a noad*/ -@d right_delimiter(A) A+5 /*second delimiter field of a fraction noad*/ -@d radical_noad (inner_noad+1) /*|type| of a noad for square roots*/ -@d radical_noad_size 5 /*number of |mem| words in a radical noad*/ -@d fraction_noad (radical_noad+1) /*|type| of a noad for generalized fractions*/ -@d fraction_noad_size 6 /*number of |mem| words in a fraction noad*/ -@d small_fam(A) mem[A].qqqq.b0 /*|fam| for ``small'' delimiter*/ -@d small_char(A) mem[A].qqqq.b1 /*|character| for ``small'' delimiter*/ -@d large_fam(A) mem[A].qqqq.b2 /*|fam| for ``large'' delimiter*/ -@d large_char(A) mem[A].qqqq.b3 /*|character| for ``large'' delimiter*/ -@d thickness(A) width(A) /*|thickness| field in a fraction noad*/ -@d default_code 010000000000 /*denotes |default_rule_thickness|*/ -@d numerator(A) supscr(A) /*|numerator| field in a fraction noad*/ -@d denominator(A) subscr(A) /*|denominator| field in a fraction noad*/ - -@ The global variable |empty_field| is set up for initialization of empty -fields in new noads. Similarly, |null_delimiter| is for the initialization -of delimiter fields. - -@<Glob...@>= -static two_halves @!empty_field; -static four_quarters @!null_delimiter; - -@ @<Set init...@>= -empty_field.rh=empty;empty_field.lh=null;@/ -null_delimiter.b0=0;null_delimiter.b1=min_quarterword;@/ -null_delimiter.b2=0;null_delimiter.b3=min_quarterword; - -@ The |new_noad| function creates an |ord_noad| that is completely null. - -@p static pointer new_noad(void) -{@+pointer p; -p=get_node(noad_size); -type(p)=ord_noad;subtype(p)=normal; -mem[nucleus(p)].hh=empty_field; -mem[subscr(p)].hh=empty_field; -mem[supscr(p)].hh=empty_field; -return p; -} - -@ A few more kinds of noads will complete the set: An |under_noad| has its -nucleus underlined; an |over_noad| has it overlined. An |accent_noad| places -an accent over its nucleus; the accent character appears as -|fam(accent_chr(p))| and |character(accent_chr(p))|. A |vcenter_noad| -centers its nucleus vertically with respect to the axis of the formula; -in such noads we always have |math_type(nucleus(p))==sub_box|. - -And finally, we have |left_noad| and |right_noad| types, to implement -\TeX's \.{\\left} and \.{\\right} as well as \eTeX's \.{\\middle}. -The |nucleus| of such noads is -replaced by a |delimiter| field; thus, for example, `\.{\\left(}' produces -a |left_noad| such that |delimiter(p)| holds the family and character -codes for all left parentheses. A |left_noad| never appears in an mlist -except as the first element, and a |right_noad| never appears in an mlist -except as the last element; furthermore, we either have both a |left_noad| -and a |right_noad|, or neither one is present. The |subscr| and |supscr| -fields are always |empty| in a |left_noad| and a |right_noad|. - -@d under_noad (fraction_noad+1) /*|type| of a noad for underlining*/ -@d over_noad (under_noad+1) /*|type| of a noad for overlining*/ -@d accent_noad (over_noad+1) /*|type| of a noad for accented subformulas*/ -@d accent_noad_size 5 /*number of |mem| words in an accent noad*/ -@d accent_chr(A) A+4 /*the |accent_chr| field of an accent noad*/ -@d vcenter_noad (accent_noad+1) /*|type| of a noad for \.{\\vcenter}*/ -@d left_noad (vcenter_noad+1) /*|type| of a noad for \.{\\left}*/ -@d right_noad (left_noad+1) /*|type| of a noad for \.{\\right}*/ -@d delimiter(A) nucleus(A) /*|delimiter| field in left and right noads*/ -@d middle_noad 1 /*|subtype| of right noad representing \.{\\middle}*/ -@d scripts_allowed(A) (type(A) >= ord_noad)&&(type(A) < left_noad) - -@ Math formulas can also contain instructions like \.{\\textstyle} that -override \TeX's normal style rules. A |style_node| is inserted into the -data structure to record such instructions; it is three words long, so it -is considered a node instead of a noad. The |subtype| is either |display_style| -or |text_style| or |script_style| or |script_script_style|. The -second and third words of a |style_node| are not used, but they are -present because a |choice_node| is converted to a |style_node|. - -\TeX\ uses even numbers 0, 2, 4, 6 to encode the basic styles -|display_style|, \dots, |script_script_style|, and adds~1 to get the -``cramped'' versions of these styles. This gives a numerical order that -is backwards from the convention of Appendix~G in {\sl The \TeX book\/}; -i.e., a smaller style has a larger numerical value. -@:TeXbook}{\sl The \TeX book@> - -@d style_node (unset_node+1) /*|type| of a style node*/ -@d style_node_size 3 /*number of words in a style node*/ -@d display_style 0 /*|subtype| for \.{\\displaystyle}*/ -@d text_style 2 /*|subtype| for \.{\\textstyle}*/ -@d script_style 4 /*|subtype| for \.{\\scriptstyle}*/ -@d script_script_style 6 /*|subtype| for \.{\\scriptscriptstyle}*/ -@d cramped 1 /*add this to an uncramped style if you want to cramp it*/ - -@p static pointer new_style(small_number @!s) /*create a style node*/ -{@+pointer p; /*the new node*/ -p=get_node(style_node_size);type(p)=style_node; -subtype(p)=s;width(p)=0;depth(p)=0; /*the |width| and |depth| are not used*/ -return p; -} - -@ Finally, the \.{\\mathchoice} primitive creates a |choice_node|, which -has special subfields |display_mlist|, |text_mlist|, |script_mlist|, -and |script_script_mlist| pointing to the mlists for each style. - -@d choice_node (unset_node+2) /*|type| of a choice node*/ -@d display_mlist(A) info(A+1) /*mlist to be used in display style*/ -@d text_mlist(A) link(A+1) /*mlist to be used in text style*/ -@d script_mlist(A) info(A+2) /*mlist to be used in script style*/ -@d script_script_mlist(A) link(A+2) /*mlist to be used in scriptscript style*/ - -@p static pointer new_choice(void) /*create a choice node*/ -{@+pointer p; /*the new node*/ -p=get_node(style_node_size);type(p)=choice_node; -subtype(p)=0; /*the |subtype| is not used*/ -display_mlist(p)=null;text_mlist(p)=null;script_mlist(p)=null; -script_script_mlist(p)=null; -return p; -} - -@ Let's consider now the previously unwritten part of |show_node_list| -that displays the things that can only be present in mlists; this -program illustrates how to access the data structures just defined. - -In the context of the following program, |p| points to a node or noad that -should be displayed, and the current string contains the ``recursion history'' -that leads to this point. The recursion history consists of a dot for each -outer level in which |p| is subsidiary to some node, or in which |p| is -subsidiary to the |nucleus| field of some noad; the dot is replaced by -`\.\_' or `\.\^' or `\./' or `\.\\' if |p| is descended from the |subscr| -or |supscr| or |denominator| or |numerator| fields of noads. For example, -the current string would be `\.{.\^.\_/}' if |p| points to the |ord_noad| for -|x| in the (ridiculous) formula -`\.{\$\\sqrt\{a\^\{\\mathinner\{b\_\{c\\over x+y\}\}\}\}\$}'. - -@<Cases of |show_node_list| that arise...@>= -case style_node: print_style(subtype(p));@+break; -case choice_node: @<Display choice node |p|@>@;@+break; -case ord_noad: case op_noad: case bin_noad: case rel_noad: case open_noad: case close_noad: case punct_noad: case inner_noad: - case radical_noad: case over_noad: case under_noad: case vcenter_noad: case accent_noad: - case left_noad: case right_noad: @<Display normal noad |p|@>@;@+break; -case fraction_noad: @<Display fraction noad |p|@>@;@+break; - -@ Here are some simple routines used in the display of noads. - -@<Declare procedures needed for displaying the elements of mlists@>= -static void print_fam_and_char(pointer @!p) /*prints family and character*/ -{@+print_esc("fam");print_int(fam(p));print_char(' '); -print_ASCII(qo(character(p))); -} -@# -static void print_delimiter(pointer @!p) /*prints a delimiter as 24-bit hex value*/ -{@+int a; /*accumulator*/ -a=small_fam(p)*256+qo(small_char(p)); -a=a*0x1000+large_fam(p)*256+qo(large_char(p)); -if (a < 0) print_int(a); /*this should never happen*/ -else print_hex(a); -} - -@ The next subroutine will descend to another level of recursion when a -subsidiary mlist needs to be displayed. The parameter |c| indicates what -character is to become part of the recursion history. An empty mlist is -distinguished from a field with |math_type(p)==empty|, because these are -not equivalent (as explained above). -@^recursion@> - -@<Declare procedures needed for displaying...@>= -static void show_info(void); /*|show_node_list(info(temp_ptr))|*/ -static void print_subsidiary_data(pointer @!p, ASCII_code @!c) - /*display a noad field*/ -{@+if (cur_length >= depth_threshold) - {@+if (math_type(p)!=empty) print(" []"); - } -else{@+append_char(c); /*include |c| in the recursion history*/ - temp_ptr=p; /*prepare for |show_info| if recursion is needed*/ - switch (math_type(p)) { - case math_char: {@+print_ln();print_current_string();print_fam_and_char(p); - } @+break; - case sub_box: show_info();@+break; /*recursive call*/ - case sub_mlist: if (info(p)==null) - {@+print_ln();print_current_string();print("{}"); - } - else show_info();@+break; /*recursive call*/ - default:do_nothing; /*|empty|*/ - } @/ - flush_char; /*remove |c| from the recursion history*/ - } -} - -@ The inelegant introduction of |show_info| in the code above seems better -than the alternative of using \PASCAL's strange |forward| declaration for a -procedure with parameters. The \PASCAL\ convention about dropping parameters -from a post-|forward| procedure is, frankly, so intolerable to the author -of \TeX\ that he would rather stoop to communication via a global temporary -variable. (A similar stoopidity occurred with respect to |hlist_out| and -|vlist_out| above, and it will occur with respect to |mlist_to_hlist| below.) -@^Knuth, Donald Ervin@> -@:PASCAL}{\PASCAL@> - -@p static void show_info(void) /*the reader will kindly forgive this*/ -{@+show_node_list(info(temp_ptr)); -} - -@ @<Declare procedures needed for displaying...@>= -static void print_style(int @!c) -{@+switch (c/2) { -case 0: print_esc("displaystyle");@+break; /*|display_style==0|*/ -case 1: print_esc("textstyle");@+break; /*|text_style==2|*/ -case 2: print_esc("scriptstyle");@+break; /*|script_style==4|*/ -case 3: print_esc("scriptscriptstyle");@+break; /*|script_script_style==6|*/ -default:print("Unknown style!"); -} -} - -@ @<Display choice node |p|@>= -{@+print_esc("mathchoice"); -append_char('D');show_node_list(display_mlist(p));flush_char; -append_char('T');show_node_list(text_mlist(p));flush_char; -append_char('S');show_node_list(script_mlist(p));flush_char; -append_char('s');show_node_list(script_script_mlist(p));flush_char; -} - -@ @<Display normal noad |p|@>= -{@+switch (type(p)) { -case ord_noad: print_esc("mathord");@+break; -case op_noad: print_esc("mathop");@+break; -case bin_noad: print_esc("mathbin");@+break; -case rel_noad: print_esc("mathrel");@+break; -case open_noad: print_esc("mathopen");@+break; -case close_noad: print_esc("mathclose");@+break; -case punct_noad: print_esc("mathpunct");@+break; -case inner_noad: print_esc("mathinner");@+break; -case over_noad: print_esc("overline");@+break; -case under_noad: print_esc("underline");@+break; -case vcenter_noad: print_esc("vcenter");@+break; -case radical_noad: {@+print_esc("radical");print_delimiter(left_delimiter(p)); - } @+break; -case accent_noad: {@+print_esc("accent");print_fam_and_char(accent_chr(p)); - } @+break; -case left_noad: {@+print_esc("left");print_delimiter(delimiter(p)); - } @+break; -case right_noad: {@+if (subtype(p)==normal) print_esc("right"); - else print_esc("middle"); - print_delimiter(delimiter(p)); - } -} -if (type(p) < left_noad) - {@+if (subtype(p)!=normal) - if (subtype(p)==limits) print_esc("limits"); - else print_esc("nolimits"); - print_subsidiary_data(nucleus(p),'.'); - } -print_subsidiary_data(supscr(p),'^'); -print_subsidiary_data(subscr(p),'_'); -} - -@ @<Display fraction noad |p|@>= -{@+print_esc("fraction, thickness "); -if (thickness(p)==default_code) print("= default"); -else print_scaled(thickness(p)); -if ((small_fam(left_delimiter(p))!=0)||@+ - (small_char(left_delimiter(p))!=min_quarterword)||@| - (large_fam(left_delimiter(p))!=0)||@| - (large_char(left_delimiter(p))!=min_quarterword)) - {@+print(", left-delimiter ");print_delimiter(left_delimiter(p)); - } -if ((small_fam(right_delimiter(p))!=0)||@| - (small_char(right_delimiter(p))!=min_quarterword)||@| - (large_fam(right_delimiter(p))!=0)||@| - (large_char(right_delimiter(p))!=min_quarterword)) - {@+print(", right-delimiter ");print_delimiter(right_delimiter(p)); - } -print_subsidiary_data(numerator(p),'\\'); -print_subsidiary_data(denominator(p),'/'); -} - -@ That which can be displayed can also be destroyed. - -@<Cases of |flush_node_list| that arise...@>= -case style_node: {@+free_node(p, style_node_size);goto done; - } -case choice_node: {@+flush_node_list(display_mlist(p)); - flush_node_list(text_mlist(p)); - flush_node_list(script_mlist(p)); - flush_node_list(script_script_mlist(p)); - free_node(p, style_node_size);goto done; - } -case ord_noad: case op_noad: case bin_noad: case rel_noad: case open_noad: case close_noad: case punct_noad: case inner_noad: - case radical_noad: case over_noad: case under_noad: case vcenter_noad: case accent_noad: @t@>@;@/ - {@+if (math_type(nucleus(p)) >= sub_box) - flush_node_list(info(nucleus(p))); - if (math_type(supscr(p)) >= sub_box) - flush_node_list(info(supscr(p))); - if (math_type(subscr(p)) >= sub_box) - flush_node_list(info(subscr(p))); - if (type(p)==radical_noad) free_node(p, radical_noad_size); - else if (type(p)==accent_noad) free_node(p, accent_noad_size); - else free_node(p, noad_size); - goto done; - } -case left_noad: case right_noad: {@+free_node(p, noad_size);goto done; - } -case fraction_noad: {@+flush_node_list(info(numerator(p))); - flush_node_list(info(denominator(p))); - free_node(p, fraction_noad_size);goto done; - } - -@* Subroutines for math mode. -In order to convert mlists to hlists, i.e., noads to nodes, we need several -subroutines that are conveniently dealt with now. - -Let us first introduce the macros that make it easy to get at the parameters and -other font information. A size code, which is a multiple of 16, is added to a -family number to get an index into the table of internal font numbers -for each combination of family and size. (Be alert: Size codes get -larger as the type gets smaller.) - -@d text_size 0 /*size code for the largest size in a family*/ -@d script_size 16 /*size code for the medium size in a family*/ -@d script_script_size 32 /*size code for the smallest size in a family*/ - -@<Basic printing procedures@>= -static void print_size(int @!s) -{@+if (s==text_size) print_esc("textfont"); -else if (s==script_size) print_esc("scriptfont"); -else print_esc("scriptscriptfont"); -} - -@ Before an mlist is converted to an hlist, \TeX\ makes sure that -the fonts in family~2 have enough parameters to be math-symbol -fonts, and that the fonts in family~3 have enough parameters to be -math-extension fonts. The math-symbol parameters are referred to by using the -following macros, which take a size code as their parameter; for example, -|num1(cur_size)| gives the value of the |num1| parameter for the current size. -@^parameters for symbols@> -@^font parameters@> - -@d mathsy_end(A) fam_fnt(2+A)]].sc -@d mathsy(A) font_info[A+param_base[mathsy_end -@d math_x_height mathsy(5) /*height of `\.x'*/ -@d math_quad mathsy(6) /*\.{18mu}*/ -@d num1 mathsy(8) /*numerator shift-up in display styles*/ -@d num2 mathsy(9) /*numerator shift-up in non-display, non-\.{\\atop}*/ -@d num3 mathsy(10) /*numerator shift-up in non-display \.{\\atop}*/ -@d denom1 mathsy(11) /*denominator shift-down in display styles*/ -@d denom2 mathsy(12) /*denominator shift-down in non-display styles*/ -@d sup1 mathsy(13) /*superscript shift-up in uncramped display style*/ -@d sup2 mathsy(14) /*superscript shift-up in uncramped non-display*/ -@d sup3 mathsy(15) /*superscript shift-up in cramped styles*/ -@d sub1 mathsy(16) /*subscript shift-down if superscript is absent*/ -@d sub2 mathsy(17) /*subscript shift-down if superscript is present*/ -@d sup_drop mathsy(18) /*superscript baseline below top of large box*/ -@d sub_drop mathsy(19) /*subscript baseline below bottom of large box*/ -@d delim1 mathsy(20) /*size of \.{\\atopwithdelims} delimiters - in display styles*/ -@d delim2 mathsy(21) /*size of \.{\\atopwithdelims} delimiters in non-displays*/ -@d axis_height mathsy(22) /*height of fraction lines above the baseline*/ -@d total_mathsy_params 22 - -@ The math-extension parameters have similar macros, but the size code is -omitted (since it is always |cur_size| when we refer to such parameters). -@^parameters for symbols@> -@^font parameters@> - -@d mathex(A) font_info[A+param_base[fam_fnt(3+cur_size)]].sc -@d default_rule_thickness mathex(8) /*thickness of \.{\\over} bars*/ -@d big_op_spacing1 mathex(9) /*minimum clearance above a displayed op*/ -@d big_op_spacing2 mathex(10) /*minimum clearance below a displayed op*/ -@d big_op_spacing3 mathex(11) /*minimum baselineskip above displayed op*/ -@d big_op_spacing4 mathex(12) /*minimum baselineskip below displayed op*/ -@d big_op_spacing5 mathex(13) /*padding above and below displayed limits*/ -@d total_mathex_params 13 - -@ We also need to compute the change in style between mlists and their -subsidiaries. The following macros define the subsidiary style for -an overlined nucleus (|cramped_style|), for a subscript or a superscript -(|sub_style| or |sup_style|), or for a numerator or denominator (|num_style| -or |denom_style|). - -@d cramped_style(A) 2*(A/2)+cramped /*cramp the style*/ -@d sub_style(A) 2*(A/4)+script_style+cramped /*smaller and cramped*/ -@d sup_style(A) 2*(A/4)+script_style+(A%2) /*smaller*/ -@d num_style(A) A+2-2*(A/6) /*smaller unless already script-script*/ -@d denom_style(A) 2*(A/2)+cramped+2-2*(A/6) /*smaller, cramped*/ - -@ When the style changes, the following piece of program computes associated -information: - -@<Set up the values of |cur_size| and |cur_mu|, based on |cur_style|@>= -{@+if (cur_style < script_style) cur_size=text_size; -else cur_size=16*((cur_style-text_style)/2); -cur_mu=x_over_n(math_quad(cur_size), 18); -} - -@ Here is a function that returns a pointer to a rule node having a given -thickness |t|. The rule will extend horizontally to the boundary of the vlist -that eventually contains it. - -@p static pointer fraction_rule(scaled @!t) - /*construct the bar for a fraction*/ -{@+pointer p; /*the new node*/ -p=new_rule();height(p)=t;depth(p)=0;return p; -} - -@ The |overbar| function returns a pointer to a vlist box that consists of -a given box |b|, above which has been placed a kern of height |k| under a -fraction rule of thickness |t| under additional space of height |t|. - -@p static pointer overbar(pointer @!b, scaled @!k, scaled @!t) -{@+pointer p, @!q; /*nodes being constructed*/ -p=new_kern(k);link(p)=b;q=fraction_rule(t);link(q)=p; -p=new_kern(t);link(p)=q;return vpack(p, natural); -} - -@ The |var_delimiter| function, which finds or constructs a sufficiently -large delimiter, is the most interesting of the auxiliary functions that -currently concern us. Given a pointer |d| to a delimiter field in some noad, -together with a size code |s| and a vertical distance |v|, this function -returns a pointer to a box that contains the smallest variant of |d| whose -height plus depth is |v| or more. (And if no variant is large enough, it -returns the largest available variant.) In particular, this routine will -construct arbitrarily large delimiters from extensible components, if -|d| leads to such characters. - -The value returned is a box whose |shift_amount| has been set so that -the box is vertically centered with respect to the axis in the given size. -If a built-up symbol is returned, the height of the box before shifting -will be the height of its topmost component. - -@p @t\4@>@<Declare subprocedures for |var_delimiter|@>@; -static pointer var_delimiter(pointer @!d, small_number @!s, scaled @!v) -{@+ -pointer b; /*the box that will be constructed*/ -internal_font_number @!f, @!g; /*best-so-far and tentative font codes*/ -quarterword @!c, @!x, @!y; /*best-so-far and tentative character codes*/ -int @!m, @!n; /*the number of extensible pieces*/ -scaled @!u; /*height-plus-depth of a tentative character*/ -scaled @!w; /*largest height-plus-depth so far*/ -four_quarters @!q; /*character info*/ -eight_bits @!hd; /*height-depth byte*/ -four_quarters @!r; /*extensible pieces*/ -small_number @!z; /*runs through font family members*/ -bool @!large_attempt; /*are we trying the ``large'' variant?*/ -f=null_font;w=0;large_attempt=false; -z=small_fam(d);x=small_char(d); -loop@+{@+@<Look at the variants of |(z,x)|; set |f| and |c| whenever a better character -is found; |goto found| as soon as a large enough variant is encountered@>; - if (large_attempt) goto found; /*there were none large enough*/ - large_attempt=true;z=large_fam(d);x=large_char(d); - } -found: if (f!=null_font) - @<Make variable |b| point to a box for |(f,c)|@>; -else{@+b=new_null_box(); - width(b)=null_delimiter_space; /*use this width if no delimiter was found*/ - } -shift_amount(b)=half(height(b)-depth(b))-axis_height(s); -return b; -} - -@ The search process is complicated slightly by the facts that some of the -characters might not be present in some of the fonts, and they might not -be probed in increasing order of height. - -@<Look at the variants of |(z,x)|; set |f| and |c|...@>= -if ((z!=0)||(x!=min_quarterword)) - {@+z=z+s+16; - @/do@+{z=z-16;g=fam_fnt(z); - if (g!=null_font) - @<Look at the list of characters starting with |x| in font |g|; set |f| and |c| -whenever a better character is found; |goto found| as soon as a large enough variant -is encountered@>; - }@+ while (!(z < 16)); - } - -@ @<Look at the list of characters starting with |x|...@>= -{@+y=x; -if ((qo(y) >= font_bc[g])&&(qo(y) <= font_ec[g])) - {@+resume: q=char_info(g, y); - if (char_exists(q)) - {@+if (char_tag(q)==ext_tag) - {@+f=g;c=y;goto found; - } - hd=height_depth(q); - u=char_height(g, hd)+char_depth(g, hd); - if (u > w) - {@+f=g;c=y;w=u; - if (u >= v) goto found; - } - if (char_tag(q)==list_tag) - {@+y=rem_byte(q);goto resume; - } - } - } -} - -@ Here is a subroutine that creates a new box, whose list contains a -single character, and whose width includes the italic correction for -that character. The height or depth of the box will be negative, if -the height or depth of the character is negative; thus, this routine -may deliver a slightly different result than |hpack| would produce. - -@<Declare subprocedures for |var_delimiter|@>= -static pointer char_box(internal_font_number @!f, quarterword @!c) -{@+four_quarters q; -eight_bits @!hd; /*|height_depth| byte*/ -pointer @!b, @!p; /*the new box and its character node*/ -q=char_info(f, c);hd=height_depth(q); -b=new_null_box();width(b)=char_width(f, q)+char_italic(f, q); -height(b)=char_height(f, hd);depth(b)=char_depth(f, hd); -p=get_avail();character(p)=c;font(p)=f;list_ptr(b)=p;return b; -} - -@ When the following code is executed, |char_tag(q)| will be equal to -|ext_tag| if and only if a built-up symbol is supposed to be returned. - -@<Make variable |b| point to a box for |(f,c)|@>= -if (char_tag(q)==ext_tag) - @<Construct an extensible character in a new box |b|, using recipe |rem_byte(q)| -and font |f|@>@; -else b=char_box(f, c) - -@ When we build an extensible character, it's handy to have the -following subroutine, which puts a given character on top -of the characters already in box |b|: - -@<Declare subprocedures for |var_delimiter|@>= -static void stack_into_box(pointer @!b, internal_font_number @!f, - quarterword @!c) -{@+pointer p; /*new node placed into |b|*/ -p=char_box(f, c);link(p)=list_ptr(b);list_ptr(b)=p; -height(b)=height(p); -} - -@ Another handy subroutine computes the height plus depth of -a given character: - -@<Declare subprocedures for |var_delimiter|@>= -static scaled height_plus_depth(internal_font_number @!f, quarterword @!c) -{@+four_quarters q; -eight_bits @!hd; /*|height_depth| byte*/ -q=char_info(f, c);hd=height_depth(q); -return char_height(f, hd)+char_depth(f, hd); -} - -@ @<Construct an extensible...@>= -{@+b=new_null_box(); -type(b)=vlist_node; -r=font_info[exten_base[f]+rem_byte(q)].qqqq;@/ -@<Compute the minimum suitable height, |w|, and the corresponding number of extension -steps, |n|; also set |width(b)|@>; -c=ext_bot(r); -if (c!=min_quarterword) stack_into_box(b, f, c); -c=ext_rep(r); -for (m=1; m<=n; m++) stack_into_box(b, f, c); -c=ext_mid(r); -if (c!=min_quarterword) - {@+stack_into_box(b, f, c);c=ext_rep(r); - for (m=1; m<=n; m++) stack_into_box(b, f, c); - } -c=ext_top(r); -if (c!=min_quarterword) stack_into_box(b, f, c); -depth(b)=w-height(b); -} - -@ The width of an extensible character is the width of the repeatable -module. If this module does not have positive height plus depth, -we don't use any copies of it, otherwise we use as few as possible -(in groups of two if there is a middle part). - -@<Compute the minimum suitable height, |w|, and...@>= -c=ext_rep(r);u=height_plus_depth(f, c); -w=0;q=char_info(f, c);width(b)=char_width(f, q)+char_italic(f, q);@/ -c=ext_bot(r);@+if (c!=min_quarterword) w=w+height_plus_depth(f, c); -c=ext_mid(r);@+if (c!=min_quarterword) w=w+height_plus_depth(f, c); -c=ext_top(r);@+if (c!=min_quarterword) w=w+height_plus_depth(f, c); -n=0; -if (u > 0) while (w < v) - {@+w=w+u;incr(n); - if (ext_mid(r)!=min_quarterword) w=w+u; - } - -@ The next subroutine is much simpler; it is used for numerators and -denominators of fractions as well as for displayed operators and -their limits above and below. It takes a given box~|b| and -changes it so that the new box is centered in a box of width~|w|. -The centering is done by putting \.{\\hss} glue at the left and right -of the list inside |b|, then packaging the new box; thus, the -actual box might not really be centered, if it already contains -infinite glue. - -The given box might contain a single character whose italic correction -has been added to the width of the box; in this case a compensating -kern is inserted. - -@p static pointer rebox(pointer @!b, scaled @!w) -{@+pointer p; /*temporary register for list manipulation*/ -internal_font_number @!f; /*font in a one-character box*/ -scaled @!v; /*width of a character without italic correction*/ -if ((width(b)!=w)&&(list_ptr(b)!=null)) - {@+if (type(b)==vlist_node) b=hpack(b, natural); - p=list_ptr(b); - if ((is_char_node(p))&&(link(p)==null)) - {@+f=font(p);v=char_width(f, char_info(f, character(p))); - if (v!=width(b)) link(p)=new_kern(width(b)-v); - } - list_ptr(b)=null; flush_node_list(b); - b=new_glue(ss_glue);link(b)=p; - while (link(p)!=null) p=link(p); - link(p)=new_glue(ss_glue); - return hpack(b, w, 0, 0, exactly); - } -else{@+width(b)=w;return b; - } -} - -@ Here is a subroutine that creates a new glue specification from another -one that is expressed in `\.{mu}', given the value of the math unit. - -@d mu_mult(A) nx_plus_y(n, A, xn_over_d(A, f, 0200000)) - -@p static pointer math_glue(pointer @!g, scaled @!m) -{@+pointer p; /*the new glue specification*/ -int @!n; /*integer part of |m|*/ -scaled @!f; /*fraction part of |m|*/ -n=x_over_n(m, 0200000);f=rem;@/ -if (f < 0) - {@+decr(n);f=f+0200000; - } -p=get_node(glue_spec_size); -width(p)=mu_mult(width(g)); /*convert \.{mu} to \.{pt}*/ -stretch_order(p)=stretch_order(g); -if (stretch_order(p)==normal) stretch(p)=mu_mult(stretch(g)); -else stretch(p)=stretch(g); -shrink_order(p)=shrink_order(g); -if (shrink_order(p)==normal) shrink(p)=mu_mult(shrink(g)); -else shrink(p)=shrink(g); -return p; -} - -@ The |math_kern| subroutine removes |mu_glue| from a kern node, given -the value of the math unit. - -@p static void math_kern(pointer @!p, scaled @!m) -{@+int @!n; /*integer part of |m|*/ -scaled @!f; /*fraction part of |m|*/ -if (subtype(p)==mu_glue) - {@+n=x_over_n(m, 0200000);f=rem;@/ - if (f < 0) - {@+decr(n);f=f+0200000; - } - width(p)=mu_mult(width(p));subtype(p)=explicit; - } -} - -@ Sometimes it is necessary to destroy an mlist. The following -subroutine empties the current list, assuming that |abs(mode)==mmode|. - -@p static void flush_math(void) -{@+flush_node_list(link(head));flush_node_list(incompleat_noad); -link(head)=null;tail=head;incompleat_noad=null; -} - -@* Typesetting math formulas. -\TeX's most important routine for dealing with formulas is called -|mlist_to_hlist|. After a formula has been scanned and represented as an -mlist, this routine converts it to an hlist that can be placed into a box -or incorporated into the text of a paragraph. There are three implicit -parameters, passed in global variables: |cur_mlist| points to the first -node or noad in the given mlist (and it might be |null|); |cur_style| is a -style code; and |mlist_penalties| is |true| if penalty nodes for potential -line breaks are to be inserted into the resulting hlist. After -|mlist_to_hlist| has acted, |link(temp_head)| points to the translated hlist. - -Since mlists can be inside mlists, the procedure is recursive. And since this -is not part of \TeX's inner loop, the program has been written in a manner -that stresses compactness over efficiency. -@^recursion@> - -@<Glob...@>= -static pointer @!cur_mlist; /*beginning of mlist to be translated*/ -static small_number @!cur_style; /*style code at current place in the list*/ -static small_number @!cur_size; /*size code corresponding to |cur_style|*/ -static scaled @!cur_mu; /*the math unit width corresponding to |cur_size|*/ -static bool @!mlist_penalties; /*should |mlist_to_hlist| insert penalties?*/ - -@ The recursion in |mlist_to_hlist| is due primarily to a subroutine -called |clean_box| that puts a given noad field into a box using a given -math style; |mlist_to_hlist| can call |clean_box|, which can call -|mlist_to_hlist|. -@^recursion@> - -The box returned by |clean_box| is ``clean'' in the -sense that its |shift_amount| is zero. - -@p static void mlist_to_hlist(void);@/ -static pointer clean_box(pointer @!p, small_number @!s) -{@+ -pointer q; /*beginning of a list to be boxed*/ -small_number @!save_style; /*|cur_style| to be restored*/ -pointer @!x; /*box to be returned*/ -pointer @!r; /*temporary pointer*/ -switch (math_type(p)) { -case math_char: {@+cur_mlist=new_noad();mem[nucleus(cur_mlist)]=mem[p]; - } @+break; -case sub_box: {@+q=info(p);goto found; - } -case sub_mlist: cur_mlist=info(p);@+break; -default:{@+q=new_null_box();goto found; - } -} @/ -save_style=cur_style;cur_style=s;mlist_penalties=false;@/ -mlist_to_hlist();q=link(temp_head); /*recursive call*/ -cur_style=save_style; /*restore the style*/ -@<Set up the values of |cur_size| and |cur_mu|, based on |cur_style|@>; -found: if (is_char_node(q)||(q==null)) x=hpack(q, natural); - else if ((link(q)==null)&&(type(q) <= vlist_node)&&(shift_amount(q)==0)) - x=q; /*it's already clean*/ - else x=hpack(q, natural); -@<Simplify a trivial box@>; -return x; -} - -@ Here we save memory space in a common case. - -@<Simplify a trivial box@>= -q=list_ptr(x); -if (is_char_node(q)) - {@+r=link(q); - if (r!=null) if (link(r)==null) if (!is_char_node(r)) - if (type(r)==kern_node) /*unneeded italic correction*/ - {@+free_node(r, small_node_size);link(q)=null; - } - } - -@ It is convenient to have a procedure that converts a |math_char| -field to an ``unpacked'' form. The |fetch| routine sets |cur_f|, |cur_c|, -and |cur_i| to the font code, character code, and character information bytes of -a given noad field. It also takes care of issuing error messages for -nonexistent characters; in such cases, |char_exists(cur_i)| will be |false| -after |fetch| has acted, and the field will also have been reset to |empty|. - -@p static void fetch(pointer @!a) /*unpack the |math_char| field |a|*/ -{@+cur_c=character(a);cur_f=fam_fnt(fam(a)+cur_size); -if (cur_f==null_font) - @<Complain about an undefined family and set |cur_i| null@>@; -else{@+if ((qo(cur_c) >= font_bc[cur_f])&&(qo(cur_c) <= font_ec[cur_f])) - cur_i=char_info(cur_f, cur_c); - else cur_i=null_character; - if (!(char_exists(cur_i))) - {@+char_warning(cur_f, qo(cur_c)); - math_type(a)=empty;cur_i=null_character; - } - } -} - -@ @<Complain about an undefined family...@>= -{@+print_err("");print_size(cur_size);print_char(' '); -print_int(fam(a));print(" is undefined (character "); -print_ASCII(qo(cur_c));print_char(')'); -help4("Somewhere in the math formula just ended, you used the",@/ -"stated character from an undefined font family. For example,",@/ -"plain TeX doesn't allow \\it or \\sl in subscripts. Proceed,",@/ -"and I'll try to forget that I needed that character."); -error();cur_i=null_character;math_type(a)=empty; -} - -@ The outputs of |fetch| are placed in global variables. - -@<Glob...@>= -static internal_font_number @!cur_f; /*the |font| field of a |math_char|*/ -static quarterword @!cur_c; /*the |character| field of a |math_char|*/ -static four_quarters @!cur_i; /*the |char_info| of a |math_char|, - or a lig/kern instruction*/ - -@ We need to do a lot of different things, so |mlist_to_hlist| makes two -passes over the given mlist. - -The first pass does most of the processing: It removes ``mu'' spacing from -glue, it recursively evaluates all subsidiary mlists so that only the -top-level mlist remains to be handled, it puts fractions and square roots -and such things into boxes, it attaches subscripts and superscripts, and -it computes the overall height and depth of the top-level mlist so that -the size of delimiters for a |left_noad| and a |right_noad| will be known. -The hlist resulting from each noad is recorded in that noad's |new_hlist| -field, an integer field that replaces the |nucleus| or |thickness|. -@^recursion@> - -The second pass eliminates all noads and inserts the correct glue and -penalties between nodes. - -@d new_hlist(A) mem[nucleus(A)].i /*the translation of an mlist*/ - -@ Here is the overall plan of |mlist_to_hlist|, and the list of its -local variables. - -@p @t\4@>@<Declare math construction procedures@>@; -static void mlist_to_hlist(void) -{@+ - -pointer mlist; /*beginning of the given list*/ -bool @!penalties; /*should penalty nodes be inserted?*/ -small_number @!style; /*the given style*/ -small_number @!save_style; /*holds |cur_style| during recursion*/ -pointer @!q; /*runs through the mlist*/ -pointer @!r; /*the most recent noad preceding |q|*/ -small_number @!r_type; /*the |type| of noad |r|, or |op_noad| if |r==null|*/ -small_number @!t; /*the effective |type| of noad |q| during the second pass*/ -pointer @!p, @!x, @!y, @!z; /*temporary registers for list construction*/ -int @!pen; /*a penalty to be inserted*/ -small_number @!s; /*the size of a noad to be deleted*/ -scaled @!max_h, @!max_d; /*maximum height and depth of the list translated so far*/ -scaled @!delta; /*offset between subscript and superscript*/ -mlist=cur_mlist;penalties=mlist_penalties; -style=cur_style; /*tuck global parameters away as local variables*/ -q=mlist;r=null;r_type=op_noad;max_h=0;max_d=0; -@<Set up the values of |cur_size| and |cur_mu|, based on |cur_style|@>; -while (q!=null) @<Process node-or-noad |q| as much as possible in preparation for -the second pass of |mlist_to_hlist|, then move to the next item in the mlist@>; -@<Convert \(a)a final |bin_noad| to an |ord_noad|@>; -@<Make a second pass over the mlist, removing all noads and inserting the proper spacing -and penalties@>; -} - -@ We use the fact that no character nodes appear in an mlist, hence -the field |type(q)| is always present. - -@<Process node-or-noad...@>= -{@+@<Do first-pass processing based on |type(q)|; |goto done_with_noad| if a noad -has been fully processed, |goto check_dimensions| if it has been translated into |new_hlist(q)|, -or |goto done_with_node| if a node has been fully processed@>; -check_dimensions: z=hpack(new_hlist(q), natural); -if (height(z) > max_h) max_h=height(z); -if (depth(z) > max_d) max_d=depth(z); -list_ptr(z)=null; flush_node_list(z); -done_with_noad: r=q;r_type=type(r); -if (r_type==right_noad) - {@+r_type=left_noad;cur_style=style;@<Set up the values...@>; - } -done_with_node: q=link(q); -} - -@ One of the things we must do on the first pass is change a |bin_noad| to -an |ord_noad| if the |bin_noad| is not in the context of a binary operator. -The values of |r| and |r_type| make this fairly easy. - -@<Do first-pass processing...@>= -reswitch: delta=0; -switch (type(q)) { -case bin_noad: switch (r_type) { - case bin_noad: case op_noad: case rel_noad: case open_noad: case punct_noad: case left_noad: - {@+type(q)=ord_noad;goto reswitch; - } - default:do_nothing; - } @+break; -case rel_noad: case close_noad: case punct_noad: case right_noad: {@+@t@>@;@/ - @<Convert \(a)a final |bin_noad| to an |ord_noad|@>; - if (type(q)==right_noad) goto done_with_noad; - } @+break; -@t\4@>@<Cases for noads that can follow a |bin_noad|@>@; -@t\4@>@<Cases for nodes that can appear in an mlist, after which we |goto done_with_node|@>@; -default:confusion("mlist1"); -@:this can't happen mlist1}{\quad mlist1@> -} @/ -@<Convert \(n)|nucleus(q)| to an hlist and attach the sub/superscripts@>@; - -@ @<Convert \(a)a final |bin_noad| to an |ord_noad|@>= -if (r_type==bin_noad) type(r)=ord_noad - -@ @<Cases for nodes that can appear in an mlist...@>= -case style_node: {@+cur_style=subtype(q); - @<Set up the values of |cur_size| and |cur_mu|, based on |cur_style|@>; - goto done_with_node; - } -case choice_node: @<Change this node to a style node followed by the correct choice, -then |goto done_with_node|@>@; -case ins_node: case mark_node: case adjust_node: - case whatsit_node: case penalty_node: case disc_node: goto done_with_node; -case rule_node: {@+if (height(q) > max_h) max_h=height(q); - if (depth(q) > max_d) max_d=depth(q);goto done_with_node; - } -case glue_node: {@+@<Convert \(m)math glue to ordinary glue@>; - goto done_with_node; - } -case kern_node: {@+math_kern(q, cur_mu);goto done_with_node; - } - -@ @d choose_mlist(A) {@+p=A(q);A(q)=null;@+} - -@<Change this node to a style node...@>= -{@+switch (cur_style/2) { -case 0: choose_mlist(display_mlist)@;@+break; /*|display_style==0|*/ -case 1: choose_mlist(text_mlist)@;@+break; /*|text_style==2|*/ -case 2: choose_mlist(script_mlist)@;@+break; /*|script_style==4|*/ -case 3: choose_mlist(script_script_mlist); /*|script_script_style==6|*/ -} /*there are no other cases*/ -flush_node_list(display_mlist(q)); -flush_node_list(text_mlist(q)); -flush_node_list(script_mlist(q)); -flush_node_list(script_script_mlist(q));@/ -type(q)=style_node;subtype(q)=cur_style;width(q)=0;depth(q)=0; -if (p!=null) - {@+z=link(q);link(q)=p; - while (link(p)!=null) p=link(p); - link(p)=z; - } -goto done_with_node; -} - -@ Conditional math glue (`\.{\\nonscript}') results in a |glue_node| -pointing to |zero_glue|, with |subtype(q)==cond_math_glue|; in such a case -the node following will be eliminated if it is a glue or kern node and if the -current size is different from |text_size|. Unconditional math glue -(`\.{\\muskip}') is converted to normal glue by multiplying the dimensions -by |cur_mu|. -@!@:non\_script\_}{\.{\\nonscript} primitive@> - -@<Convert \(m)math glue to ordinary glue@>= -if (subtype(q)==mu_glue) - {@+x=glue_ptr(q); - y=math_glue(x, cur_mu);delete_glue_ref(x);glue_ptr(q)=y; - subtype(q)=normal; - } -else if ((cur_size!=text_size)&&(subtype(q)==cond_math_glue)) - {@+p=link(q); - if (p!=null) if ((type(p)==glue_node)||(type(p)==kern_node)) - {@+link(q)=link(p);link(p)=null;flush_node_list(p); - } - } - -@ @<Cases for noads that can follow a |bin_noad|@>= -case left_noad: goto done_with_noad; -case fraction_noad: {@+make_fraction(q);goto check_dimensions; - } -case op_noad: {@+delta=make_op(q); - if (subtype(q)==limits) goto check_dimensions; - } @+break; -case ord_noad: make_ord(q);@+break; -case open_noad: case inner_noad: do_nothing;@+break; -case radical_noad: make_radical(q);@+break; -case over_noad: make_over(q);@+break; -case under_noad: make_under(q);@+break; -case accent_noad: make_math_accent(q);@+break; -case vcenter_noad: make_vcenter(q);@+break; - -@ Most of the actual construction work of |mlist_to_hlist| is done -by procedures with names -like |make_fraction|, |make_radical|, etc. To illustrate -the general setup of such procedures, let's begin with a couple of -simple ones. - -@<Declare math...@>= -static void make_over(pointer @!q) -{@+info(nucleus(q))=@| - overbar(clean_box(nucleus(q), cramped_style(cur_style)),@| - 3*default_rule_thickness, default_rule_thickness); -math_type(nucleus(q))=sub_box; -} - -@ @<Declare math...@>= -static void make_under(pointer @!q) -{@+pointer p, @!x, @!y; /*temporary registers for box construction*/ -scaled @!delta; /*overall height plus depth*/ -x=clean_box(nucleus(q), cur_style); -p=new_kern(3*default_rule_thickness);link(x)=p; -link(p)=fraction_rule(default_rule_thickness); -y=vpack(x, natural); -delta=height(y)+depth(y)+default_rule_thickness; -height(y)=height(x);depth(y)=delta-height(y); -info(nucleus(q))=y;math_type(nucleus(q))=sub_box; -} - -@ @<Declare math...@>= -static void make_vcenter(pointer @!q) -{@+pointer v; /*the box that should be centered vertically*/ -scaled @!delta; /*its height plus depth*/ -v=info(nucleus(q)); -if (type(v)!=vlist_node) confusion("vcenter"); -@:this can't happen vcenter}{\quad vcenter@> -delta=height(v)+depth(v); -height(v)=axis_height(cur_size)+half(delta); -depth(v)=delta-height(v); -} - -@ According to the rules in the \.{DVI} file specifications, we ensure alignment -@^square roots@> -between a square root sign and the rule above its nucleus by assuming that the -baseline of the square-root symbol is the same as the bottom of the rule. The -height of the square-root symbol will be the thickness of the rule, and the -depth of the square-root symbol should exceed or equal the height-plus-depth -of the nucleus plus a certain minimum clearance~|clr|. The symbol will be -placed so that the actual clearance is |clr| plus half the excess. - -@<Declare math...@>= -static void make_radical(pointer @!q) -{@+pointer x, @!y; /*temporary registers for box construction*/ -scaled @!delta, @!clr; /*dimensions involved in the calculation*/ -x=clean_box(nucleus(q), cramped_style(cur_style)); -if (cur_style < text_style) /*display style*/ - clr=default_rule_thickness+(abs(math_x_height(cur_size))/4); -else{@+clr=default_rule_thickness;clr=clr+(abs(clr)/4); - } -y=var_delimiter(left_delimiter(q), cur_size, height(x)+depth(x)+clr+ - default_rule_thickness); -delta=depth(y)-(height(x)+depth(x)+clr); -if (delta > 0) clr=clr+half(delta); /*increase the actual clearance*/ -shift_amount(y)=-(height(x)+clr); -link(y)=overbar(x, clr, height(y)); -info(nucleus(q))=hpack(y, natural);math_type(nucleus(q))=sub_box; -} - -@ Slants are not considered when placing accents in math mode. The accenter is -centered over the accentee, and the accent width is treated as zero with -respect to the size of the final box. - -@<Declare math...@>= -static void make_math_accent(pointer @!q) -{@+ -pointer p, @!x, @!y; /*temporary registers for box construction*/ -int @!a; /*address of lig/kern instruction*/ -quarterword @!c; /*accent character*/ -internal_font_number @!f; /*its font*/ -four_quarters @!i; /*its |char_info|*/ -scaled @!s; /*amount to skew the accent to the right*/ -scaled @!h; /*height of character being accented*/ -scaled @!delta; /*space to remove between accent and accentee*/ -scaled @!w; /*width of the accentee, not including sub/superscripts*/ -fetch(accent_chr(q)); -if (char_exists(cur_i)) - {@+i=cur_i;c=cur_c;f=cur_f;@/ - @<Compute the amount of skew@>; - x=clean_box(nucleus(q), cramped_style(cur_style));w=width(x);h=height(x); - @<Switch to a larger accent if available and appropriate@>; - if (h < x_height(f)) delta=h;@+else delta=x_height(f); - if ((math_type(supscr(q))!=empty)||(math_type(subscr(q))!=empty)) - if (math_type(nucleus(q))==math_char) - @<Swap the subscript and superscript into box |x|@>; - y=char_box(f, c); - shift_amount(y)=s+half(w-width(y)); - width(y)=0;p=new_kern(-delta);link(p)=x;link(y)=p; - y=vpack(y, natural);width(y)=width(x); - if (height(y) < h) @<Make the height of box |y| equal to |h|@>; - info(nucleus(q))=y; - math_type(nucleus(q))=sub_box; - } -} - -@ @<Make the height of box |y|...@>= -{@+p=new_kern(h-height(y));link(p)=list_ptr(y);list_ptr(y)=p; -height(y)=h; -} - -@ @<Switch to a larger accent if available and appropriate@>= -loop@+{@+if (char_tag(i)!=list_tag) goto done; - y=rem_byte(i); - i=char_info(f, y); - if (!char_exists(i)) goto done; - if (char_width(f, i) > w) goto done; - c=y; - } -done: - -@ @<Compute the amount of skew@>= -s=0; -if (math_type(nucleus(q))==math_char) - {@+fetch(nucleus(q)); - if (char_tag(cur_i)==lig_tag) - {@+a=lig_kern_start(cur_f, cur_i); - cur_i=font_info[a].qqqq; - if (skip_byte(cur_i) > stop_flag) - {@+a=lig_kern_restart(cur_f, cur_i); - cur_i=font_info[a].qqqq; - } - loop@+{@+if (qo(next_char(cur_i))==skew_char[cur_f]) - {@+if (op_byte(cur_i) >= kern_flag) - if (skip_byte(cur_i) <= stop_flag) s=char_kern(cur_f, cur_i); - goto done1; - } - if (skip_byte(cur_i) >= stop_flag) goto done1; - a=a+qo(skip_byte(cur_i))+1; - cur_i=font_info[a].qqqq; - } - } - } -done1: - -@ @<Swap the subscript and superscript into box |x|@>= -{@+flush_node_list(x);x=new_noad(); -mem[nucleus(x)]=mem[nucleus(q)]; -mem[supscr(x)]=mem[supscr(q)]; -mem[subscr(x)]=mem[subscr(q)];@/ -mem[supscr(q)].hh=empty_field; -mem[subscr(q)].hh=empty_field;@/ -math_type(nucleus(q))=sub_mlist;info(nucleus(q))=x; -x=clean_box(nucleus(q), cur_style);delta=delta+height(x)-h;h=height(x); -} - -@ The |make_fraction| procedure is a bit different because it sets -|new_hlist(q)| directly rather than making a sub-box. - -@<Declare math...@>= -static void make_fraction(pointer @!q) -{@+pointer p, @!v, @!x, @!y, @!z; /*temporary registers for box construction*/ -scaled @!delta, @!delta1, @!delta2, @!shift_up, @!shift_down, @!clr; - /*dimensions for box calculations*/ -if (thickness(q)==default_code) thickness(q)=default_rule_thickness; -@<Create equal-width boxes |x| and |z| for the numerator and denominator, and compute -the default amounts |shift_up| and |shift_down| by which they are displaced from the -baseline@>; -if (thickness(q)==0) @<Adjust \(s)|shift_up| and |shift_down| for the case of no fraction -line@>@; -else@<Adjust \(s)|shift_up| and |shift_down| for the case of a fraction line@>; -@<Construct a vlist box for the fraction, according to |shift_up| and |shift_down|@>; -@<Put the \(f)fraction into a box with its delimiters, and make |new_hlist(q)| point -to it@>; -} - -@ @<Create equal-width boxes |x| and |z| for the numerator and denom...@>= -x=clean_box(numerator(q), num_style(cur_style)); -z=clean_box(denominator(q), denom_style(cur_style)); -if (width(x) < width(z)) x=rebox(x, width(z)); -else z=rebox(z, width(x)); -if (cur_style < text_style) /*display style*/ - {@+shift_up=num1(cur_size);shift_down=denom1(cur_size); - } -else{@+shift_down=denom2(cur_size); - if (thickness(q)!=0) shift_up=num2(cur_size); - else shift_up=num3(cur_size); - } - -@ The numerator and denominator must be separated by a certain minimum -clearance, called |clr| in the following program. The difference between -|clr| and the actual clearance is twice |delta|. - -@<Adjust \(s)|shift_up| and |shift_down| for the case of no fraction line@>= -{@+if (cur_style < text_style) clr=7*default_rule_thickness; -else clr=3*default_rule_thickness; -delta=half(clr-((shift_up-depth(x))-(height(z)-shift_down))); -if (delta > 0) - {@+shift_up=shift_up+delta; - shift_down=shift_down+delta; - } -} - -@ In the case of a fraction line, the minimum clearance depends on the actual -thickness of the line. - -@<Adjust \(s)|shift_up| and |shift_down| for the case of a fraction line@>= -{@+if (cur_style < text_style) clr=3*thickness(q); -else clr=thickness(q); -delta=half(thickness(q)); -delta1=clr-((shift_up-depth(x))-(axis_height(cur_size)+delta)); -delta2=clr-((axis_height(cur_size)-delta)-(height(z)-shift_down)); -if (delta1 > 0) shift_up=shift_up+delta1; -if (delta2 > 0) shift_down=shift_down+delta2; -} - -@ @<Construct a vlist box for the fraction...@>= -v=new_null_box();type(v)=vlist_node; -height(v)=shift_up+height(x);depth(v)=depth(z)+shift_down; -width(v)=width(x); /*this also equals |width(z)|*/ -if (thickness(q)==0) - {@+p=new_kern((shift_up-depth(x))-(height(z)-shift_down)); - link(p)=z; - } -else{@+y=fraction_rule(thickness(q));@/ - p=new_kern((axis_height(cur_size)-delta)-@|(height(z)-shift_down));@/ - link(y)=p;link(p)=z;@/ - p=new_kern((shift_up-depth(x))-(axis_height(cur_size)+delta)); - link(p)=y; - } -link(x)=p;list_ptr(v)=x - -@ @<Put the \(f)fraction into a box with its delimiters...@>= -if (cur_style < text_style) delta=delim1(cur_size); -else delta=delim2(cur_size); -x=var_delimiter(left_delimiter(q), cur_size, delta);link(x)=v;@/ -z=var_delimiter(right_delimiter(q), cur_size, delta);link(v)=z;@/ -new_hlist(q)=hpack(x, natural) - -@ If the nucleus of an |op_noad| is a single character, it is to be -centered vertically with respect to the axis, after first being enlarged -(via a character list in the font) if we are in display style. The normal -convention for placing displayed limits is to put them above and below the -operator in display style. - -The italic correction is removed from the character if there is a subscript -and the limits are not being displayed. The |make_op| -routine returns the value that should be used as an offset between -subscript and superscript. - -After |make_op| has acted, |subtype(q)| will be |limits| if and only if -the limits have been set above and below the operator. In that case, -|new_hlist(q)| will already contain the desired final box. - -@<Declare math...@>= -static scaled make_op(pointer @!q) -{@+scaled delta; /*offset between subscript and superscript*/ -pointer @!p, @!v, @!x, @!y, @!z; /*temporary registers for box construction*/ -quarterword @!c;@+four_quarters @!i; /*registers for character examination*/ -scaled @!shift_up, @!shift_down; /*dimensions for box calculation*/ -if ((subtype(q)==normal)&&(cur_style < text_style)) - subtype(q)=limits; -if (math_type(nucleus(q))==math_char) - {@+fetch(nucleus(q)); - if ((cur_style < text_style)&&(char_tag(cur_i)==list_tag)) /*make it larger*/ - {@+c=rem_byte(cur_i);i=char_info(cur_f, c); - if (char_exists(i)) - {@+cur_c=c;cur_i=i;character(nucleus(q))=c; - } - } - delta=char_italic(cur_f, cur_i);x=clean_box(nucleus(q), cur_style); - if ((math_type(subscr(q))!=empty)&&(subtype(q)!=limits)) - width(x)=width(x)-delta; /*remove italic correction*/ - shift_amount(x)=half(height(x)-depth(x))-axis_height(cur_size); - /*center vertically*/ - math_type(nucleus(q))=sub_box;info(nucleus(q))=x; - } -else delta=0; -if (subtype(q)==limits) - @<Construct a box with limits above and below it, skewed by |delta|@>; -return delta; -} - -@ The following program builds a vlist box |v| for displayed limits. The -width of the box is not affected by the fact that the limits may be skewed. - -@<Construct a box with limits above and below it...@>= -{@+x=clean_box(supscr(q), sup_style(cur_style)); -y=clean_box(nucleus(q), cur_style); -z=clean_box(subscr(q), sub_style(cur_style)); -v=new_null_box();type(v)=vlist_node;width(v)=width(y); -if (width(x) > width(v)) width(v)=width(x); -if (width(z) > width(v)) width(v)=width(z); -x=rebox(x, width(v));y=rebox(y, width(v));z=rebox(z, width(v));@/ -shift_amount(x)=half(delta);shift_amount(z)=-shift_amount(x); -height(v)=height(y);depth(v)=depth(y); -@<Attach the limits to |y| and adjust |height(v)|, |depth(v)| to account for their -presence@>; -new_hlist(q)=v; -} - -@ We use |shift_up| and |shift_down| in the following program for the -amount of glue between the displayed operator |y| and its limits |x| and -|z|. The vlist inside box |v| will consist of |x| followed by |y| followed -by |z|, with kern nodes for the spaces between and around them. - -@<Attach the limits to |y| and adjust |height(v)|, |depth(v)|...@>= -if (math_type(supscr(q))==empty) - {@+list_ptr(x)=null; flush_node_list(x);list_ptr(v)=y; - } -else{@+shift_up=big_op_spacing3-depth(x); - if (shift_up < big_op_spacing1) shift_up=big_op_spacing1; - p=new_kern(shift_up);link(p)=y;link(x)=p;@/ - p=new_kern(big_op_spacing5);link(p)=x;list_ptr(v)=p; - height(v)=height(v)+big_op_spacing5+height(x)+depth(x)+shift_up; - } -if (math_type(subscr(q))==empty)@/ - {@+list_ptr(z)=null;@+flush_node_list(z);@+} -else{@+shift_down=big_op_spacing4-height(z); - if (shift_down < big_op_spacing2) shift_down=big_op_spacing2; - p=new_kern(shift_down);link(y)=p;link(p)=z;@/ - p=new_kern(big_op_spacing5);link(z)=p; - depth(v)=depth(v)+big_op_spacing5+height(z)+depth(z)+shift_down; - } - -@ A ligature found in a math formula does not create a |ligature_node|, because -there is no question of hyphenation afterwards; the ligature will simply be -stored in an ordinary |char_node|, after residing in an |ord_noad|. - -The |math_type| is converted to |math_text_char| here if we would not want to -apply an italic correction to the current character unless it belongs -to a math font (i.e., a font with |space==0|). - -No boundary characters enter into these ligatures. - -@<Declare math...@>= -static void make_ord(pointer @!q) -{@+ -int a; /*address of lig/kern instruction*/ -pointer @!p, @!r; /*temporary registers for list manipulation*/ -restart: @t@>@;@/ -if (math_type(subscr(q))==empty) if (math_type(supscr(q))==empty) - if (math_type(nucleus(q))==math_char) - {@+p=link(q); - if (p!=null) if ((type(p) >= ord_noad)&&(type(p) <= punct_noad)) - if (math_type(nucleus(p))==math_char) - if (fam(nucleus(p))==fam(nucleus(q))) - {@+math_type(nucleus(q))=math_text_char; - fetch(nucleus(q)); - if (char_tag(cur_i)==lig_tag) - {@+a=lig_kern_start(cur_f, cur_i); - cur_c=character(nucleus(p)); - cur_i=font_info[a].qqqq; - if (skip_byte(cur_i) > stop_flag) - {@+a=lig_kern_restart(cur_f, cur_i); - cur_i=font_info[a].qqqq; - } - loop@+{@+@<If instruction |cur_i| is a kern with |cur_c|, attach the kern -after~|q|; or if it is a ligature with |cur_c|, combine noads |q| and~|p| appropriately; -then |return| if the cursor has moved past a noad, or |goto restart|@>; - if (skip_byte(cur_i) >= stop_flag) return; - a=a+qo(skip_byte(cur_i))+1; - cur_i=font_info[a].qqqq; - } - } - } - } -} - -@ Note that a ligature between an |ord_noad| and another kind of noad -is replaced by an |ord_noad|, when the two noads collapse into one. -But we could make a parenthesis (say) change shape when it follows -certain letters. Presumably a font designer will define such -ligatures only when this convention makes sense. - -\chardef\@@='174 % vertical line to indicate character retention - -@<If instruction |cur_i| is a kern with |cur_c|,...@>= -if (next_char(cur_i)==cur_c) if (skip_byte(cur_i) <= stop_flag) - if (op_byte(cur_i) >= kern_flag) - {@+p=new_kern(char_kern(cur_f, cur_i)); - link(p)=link(q);link(q)=p;return; - } - else{@+check_interrupt; /*allow a way out of infinite ligature loop*/ - switch (op_byte(cur_i)) { - case qi(1): case qi(5): character(nucleus(q))=rem_byte(cur_i);@+break; /*\.{=:\@@}, \.{=:\@@>}*/ - case qi(2): case qi(6): character(nucleus(p))=rem_byte(cur_i);@+break; /*\.{\@@=:}, \.{\@@=:>}*/ - case qi(3): case qi(7): case qi(11): {@+r=new_noad(); /*\.{\@@=:\@@}, \.{\@@=:\@@>}, \.{\@@=:\@@>>}*/ - character(nucleus(r))=rem_byte(cur_i); - fam(nucleus(r))=fam(nucleus(q));@/ - link(q)=r;link(r)=p; - if (op_byte(cur_i) < qi(11)) math_type(nucleus(r))=math_char; - else math_type(nucleus(r))=math_text_char; /*prevent combination*/ - } @+break; - default:{@+link(q)=link(p); - character(nucleus(q))=rem_byte(cur_i); /*\.{=:}*/ - mem[subscr(q)]=mem[subscr(p)];mem[supscr(q)]=mem[supscr(p)];@/ - free_node(p, noad_size); - } - } - if (op_byte(cur_i) > qi(3)) return; - math_type(nucleus(q))=math_char;goto restart; - } - -@ When we get to the following part of the program, we have ``fallen through'' -from cases that did not lead to |check_dimensions| or |done_with_noad| or -|done_with_node|. Thus, |q|~points to a noad whose nucleus may need to be -converted to an hlist, and whose subscripts and superscripts need to be -appended if they are present. - -If |nucleus(q)| is not a |math_char|, the variable |delta| is the amount -by which a superscript should be moved right with respect to a subscript -when both are present. -@^subscripts@> -@^superscripts@> - -@<Convert \(n)|nucleus(q)| to an hlist and attach the sub/superscripts@>= -switch (math_type(nucleus(q))) { -case math_char: case math_text_char: - @<Create a character node |p| for |nucleus(q)|, possibly followed by a kern node -for the italic correction, and set |delta| to the italic correction if a subscript -is present@>@;@+break; -case empty: p=null;@+break; -case sub_box: p=info(nucleus(q));@+break; -case sub_mlist: {@+cur_mlist=info(nucleus(q));save_style=cur_style; - mlist_penalties=false;mlist_to_hlist(); /*recursive call*/ -@^recursion@> - cur_style=save_style;@<Set up the values...@>; - p=hpack(link(temp_head), natural); - } @+break; -default:confusion("mlist2"); -@:this can't happen mlist2}{\quad mlist2@> -} @/ -new_hlist(q)=p; -if ((math_type(subscr(q))==empty)&&(math_type(supscr(q))==empty)) - goto check_dimensions; -make_scripts(q, delta) - -@ @<Create a character node |p| for |nucleus(q)|...@>= -{@+fetch(nucleus(q)); -if (char_exists(cur_i)) - {@+delta=char_italic(cur_f, cur_i);p=new_character(cur_f, qo(cur_c)); - if ((math_type(nucleus(q))==math_text_char)&&(space(cur_f)!=0)) - delta=0; /*no italic correction in mid-word of text font*/ - if ((math_type(subscr(q))==empty)&&(delta!=0)) - {@+link(p)=new_kern(delta);delta=0; - } - } -else p=null; -} - -@ The purpose of |make_scripts(q, delta)| is to attach the subscript and/or -superscript of noad |q| to the list that starts at |new_hlist(q)|, -given that the subscript and superscript aren't both empty. The superscript -will appear to the right of the subscript by a given distance |delta|. - -We set |shift_down| and |shift_up| to the minimum amounts to shift the -baseline of subscripts and superscripts based on the given nucleus. - -@<Declare math...@>= -static void make_scripts(pointer @!q, scaled @!delta) -{@+pointer p, @!x, @!y, @!z; /*temporary registers for box construction*/ -scaled @!shift_up, @!shift_down, @!clr; /*dimensions in the calculation*/ -small_number @!t; /*subsidiary size code*/ -p=new_hlist(q); -if (is_char_node(p)) - {@+shift_up=0;shift_down=0; - } -else{@+z=hpack(p, natural); - if (cur_style < script_style) t=script_size;@+else t=script_script_size; - shift_up=height(z)-sup_drop(t); - shift_down=depth(z)+sub_drop(t); - list_ptr(z)=null;flush_node_list(z); - } -if (math_type(supscr(q))==empty) - @<Construct a subscript box |x| when there is no superscript@>@; -else{@+@<Construct a superscript box |x|@>; - if (math_type(subscr(q))==empty) shift_amount(x)=-shift_up; - else@<Construct a sub/superscript combination box |x|, with the superscript offset -by |delta|@>; - } -if (new_hlist(q)==null) new_hlist(q)=x; -else{@+p=new_hlist(q); - while (link(p)!=null) p=link(p); - link(p)=x; - } -} - -@ When there is a subscript without a superscript, the top of the subscript -should not exceed the baseline plus four-fifths of the x-height. - -@<Construct a subscript box |x| when there is no superscript@>= -{@+x=clean_box(subscr(q), sub_style(cur_style)); -width(x)=width(x)+script_space; -if (shift_down < sub1(cur_size)) shift_down=sub1(cur_size); -clr=height(x)-(abs(math_x_height(cur_size)*4)/5); -if (shift_down < clr) shift_down=clr; -shift_amount(x)=shift_down; -} - -@ The bottom of a superscript should never descend below the baseline plus -one-fourth of the x-height. - -@<Construct a superscript box |x|@>= -{@+x=clean_box(supscr(q), sup_style(cur_style)); -width(x)=width(x)+script_space; -if (odd(cur_style)) clr=sup3(cur_size); -else if (cur_style < text_style) clr=sup1(cur_size); -else clr=sup2(cur_size); -if (shift_up < clr) shift_up=clr; -clr=depth(x)+(abs(math_x_height(cur_size))/4); -if (shift_up < clr) shift_up=clr; -} - -@ When both subscript and superscript are present, the subscript must be -separated from the superscript by at least four times |default_rule_thickness|. -If this condition would be violated, the subscript moves down, after which -both subscript and superscript move up so that the bottom of the superscript -is at least as high as the baseline plus four-fifths of the x-height. - -@<Construct a sub/superscript combination box |x|...@>= -{@+y=clean_box(subscr(q), sub_style(cur_style)); -width(y)=width(y)+script_space; -if (shift_down < sub2(cur_size)) shift_down=sub2(cur_size); -clr=4*default_rule_thickness- - ((shift_up-depth(x))-(height(y)-shift_down)); -if (clr > 0) - {@+shift_down=shift_down+clr; - clr=(abs(math_x_height(cur_size)*4)/5)-(shift_up-depth(x)); - if (clr > 0) - {@+shift_up=shift_up+clr; - shift_down=shift_down-clr; - } - } -shift_amount(x)=delta; /*superscript is |delta| to the right of the subscript*/ -p=new_kern((shift_up-depth(x))-(height(y)-shift_down));link(x)=p;link(p)=y; -x=vpack(x, natural);shift_amount(x)=shift_down; -} - -@ We have now tied up all the loose ends of the first pass of |mlist_to_hlist|. -The second pass simply goes through and hooks everything together with the -proper glue and penalties. It also handles the |left_noad| and |right_noad| that -might be present, since |max_h| and |max_d| are now known. Variable |p| points -to a node at the current end of the final hlist. - -@<Make a second pass over the mlist,...@>= -p=temp_head;link(p)=null;q=mlist;r_type=0;cur_style=style; -@<Set up the values of |cur_size| and |cur_mu|, based on |cur_style|@>; -while (q!=null) - {@+@<If node |q| is a style node, change the style and |goto delete_q|; otherwise -if it is not a noad, put it into the hlist, advance |q|, and |goto done|; otherwise -set |s| to the size of noad |q|, set |t| to the associated type (|ord_noad.. inner_noad|), -and set |pen| to the associated penalty@>; - @<Append inter-element spacing based on |r_type| and |t|@>; - @<Append any |new_hlist| entries for |q|, and any appropriate penalties@>; - if (type(q)==right_noad) t=open_noad; - r_type=t; - delete_q: r=q;q=link(q);free_node(r, s); - done: ;} - -@ Just before doing the big |case| switch in the second pass, the program -sets up default values so that most of the branches are short. - -@<If node |q| is a style node, change the style...@>= -t=ord_noad;s=noad_size;pen=inf_penalty; -switch (type(q)) { -case op_noad: case open_noad: case close_noad: case punct_noad: case inner_noad: t=type(q);@+break; -case bin_noad: {@+t=bin_noad;pen=bin_op_penalty; - } @+break; -case rel_noad: {@+t=rel_noad;pen=rel_penalty; - } @+break; -case ord_noad: case vcenter_noad: case over_noad: case under_noad: do_nothing;@+break; -case radical_noad: s=radical_noad_size;@+break; -case accent_noad: s=accent_noad_size;@+break; -case fraction_noad: s=fraction_noad_size;@+break; -case left_noad: case right_noad: t=make_left_right(q, style, max_d, max_h);@+break; -case style_node: @<Change the current style and |goto delete_q|@>@; -case whatsit_node: case penalty_node: case rule_node: case disc_node: case adjust_node: case ins_node: case mark_node: - case glue_node: case kern_node: @t@>@;@/ - {@+link(p)=q;p=q;q=link(q);link(p)=null;goto done; - } -default:confusion("mlist3"); -@:this can't happen mlist3}{\quad mlist3@> -} - -@ The |make_left_right| function constructs a left or right delimiter of -the required size and returns the value |open_noad| or |close_noad|. The -|right_noad| and |left_noad| will both be based on the original |style|, -so they will have consistent sizes. - -We use the fact that |right_noad-left_noad==close_noad-open_noad|. - -@<Declare math...@>= -static small_number make_left_right(pointer @!q, small_number @!style, - scaled @!max_d, scaled @!max_h) -{@+scaled delta, @!delta1, @!delta2; /*dimensions used in the calculation*/ -cur_style=style;@<Set up the values...@>; -delta2=max_d+axis_height(cur_size); -delta1=max_h+max_d-delta2; -if (delta2 > delta1) delta1=delta2; /*|delta1| is max distance from axis*/ -delta=(delta1/500)*delimiter_factor; -delta2=delta1+delta1-delimiter_shortfall; -if (delta < delta2) delta=delta2; -new_hlist(q)=var_delimiter(delimiter(q), cur_size, delta); -return type(q)-(left_noad-open_noad); /*|open_noad| or |close_noad|*/ -} - -@ @<Change the current style and |goto delete_q|@>= -{@+cur_style=subtype(q);s=style_node_size; -@<Set up the values of |cur_size| and |cur_mu|, based on |cur_style|@>; -goto delete_q; -} - -@ The inter-element spacing in math formulas depends on an $8\times8$ table that -\TeX\ preloads as a 64-digit string. The elements of this string have the -following significance: -$$\vbox{\halign{#\hfil\cr -\.0 means no space;\cr -\.1 means a conditional thin space (\.{\\nonscript\\mskip\\thinmuskip});\cr -\.2 means a thin space (\.{\\mskip\\thinmuskip});\cr -\.3 means a conditional medium space - (\.{\\nonscript\\mskip\\medmuskip});\cr -\.4 means a conditional thick space - (\.{\\nonscript\\mskip\\thickmuskip});\cr -\.* means an impossible case.\cr}}$$ -This is all pretty cryptic, but {\sl The \TeX book\/} explains what is -supposed to happen, and the string makes it happen. -@:TeXbook}{\sl The \TeX book@> - -A global variable |magic_offset| is computed so that if |a| and |b| are -in the range |ord_noad dotdot inner_noad|, then |str_pool[a*8+b+magic_offset]| -is the digit for spacing between noad types |a| and |b|. - -If \PASCAL\ had provided a good way to preload constant arrays, this part of -the program would not have been so strange. -@:PASCAL}{\PASCAL@> - -@d math_spacing @;@/ -@t\hskip-35pt@> -"0234000122*4000133**3**344*0400400*000000234000111*1111112341011" -@t$ \hskip-35pt$@> - -@ @<Glob...@>= -static const int @!magic_offset=-9*ord_noad; /*used to find inter-element spacing*/ - -@ @<Append inter-element spacing based on |r_type| and |t|@>= -if (r_type > 0) /*not the first noad*/ - {@+switch (so(math_spacing[r_type*8+t+magic_offset])) { - case '0': x=0;@+break; - case '1': if (cur_style < script_style) x=thin_mu_skip_code;@+else x=0;@+break; - case '2': x=thin_mu_skip_code;@+break; - case '3': if (cur_style < script_style) x=med_mu_skip_code;@+else x=0;@+break; - case '4': if (cur_style < script_style) x=thick_mu_skip_code;@+else x=0;@+break; - default:confusion("mlist4"); -@:this can't happen mlist4}{\quad mlist4@> - } - if (x!=0) - {@+y=math_glue(glue_par(x), cur_mu); - z=new_glue(y);glue_ref_count(y)=null;link(p)=z;p=z;@/ - subtype(z)=x+1; /*store a symbolic subtype*/ - } - } - -@ We insert a penalty node after the hlist entries of noad |q| if |pen| -is not an ``infinite'' penalty, and if the node immediately following |q| -is not a penalty node or a |rel_noad| or absent entirely. - -@<Append any |new_hlist| entries for |q|, and any appropriate penalties@>= -if (new_hlist(q)!=null) - {@+link(p)=new_hlist(q); - @/do@+{p=link(p); - }@+ while (!(link(p)==null)); - } -if (penalties) if (link(q)!=null) if (pen < inf_penalty) - {@+r_type=type(link(q)); - if (r_type!=penalty_node) if (r_type!=rel_noad) - {@+z=new_penalty(pen);link(p)=z;p=z; - } - } - -@* Alignment. -It's sort of a miracle whenever \.{\\halign} and \.{\\valign} work, because -they cut across so many of the control structures of \TeX. - -Therefore the -present page is probably not the best place for a beginner to start reading -this program; it is better to master everything else first. - -Let us focus our thoughts on an example of what the input might be, in order -to get some idea about how the alignment miracle happens. The example doesn't -do anything useful, but it is sufficiently general to indicate all of the -special cases that must be dealt with; please do not be disturbed by its -apparent complexity and meaninglessness. -$$\vbox{\halign{\.{#}\hfil\cr -{}\\tabskip 2pt plus 3pt\cr -{}\\halign to 300pt\{u1\#v1\&\cr -\hskip 50pt\\tabskip 1pt plus 1fil u2\#v2\&\cr -\hskip 50pt u3\#v3\\cr\cr -\hskip 25pt a1\&\\omit a2\&\\vrule\\cr\cr -\hskip 25pt \\noalign\{\\vskip 3pt\}\cr -\hskip 25pt b1\\span b2\\cr\cr -\hskip 25pt \\omit\&c2\\span\\omit\\cr\}\cr}}$$ -Here's what happens: - -\yskip -(0) When `\.{\\halign to 300pt\{}' is scanned, the |scan_spec| routine -places the 300pt dimension onto the |save_stack|, and an |align_group| -code is placed above it. This will make it possible to complete the alignment -when the matching `\.\}' is found. - -(1) The preamble is scanned next. Macros in the preamble are not expanded, -@^preamble@> -except as part of a tabskip specification. For example, if \.{u2} had been -a macro in the preamble above, it would have been expanded, since \TeX\ -must look for `\.{minus...}' as part of the tabskip glue. A ``preamble list'' -is constructed based on the user's preamble; in our case it contains the -following seven items: -$$\vbox{\halign{\.{#}\hfil\qquad&(#)\hfil\cr -{}\\glue 2pt plus 3pt&the tabskip preceding column 1\cr -{}\\alignrecord, width $-\infty$&preamble info for column 1\cr -{}\\glue 2pt plus 3pt&the tabskip between columns 1 and 2\cr -{}\\alignrecord, width $-\infty$&preamble info for column 2\cr -{}\\glue 1pt plus 1fil&the tabskip between columns 2 and 3\cr -{}\\alignrecord, width $-\infty$&preamble info for column 3\cr -{}\\glue 1pt plus 1fil&the tabskip following column 3\cr}}$$ -These ``alignrecord'' entries have the same size as an |unset_node|, -since they will later be converted into such nodes. However, at the -moment they have no |type| or |subtype| fields; they have |info| fields -instead, and these |info| fields are initially set to the value |end_span|, -for reasons explained below. Furthermore, the alignrecord nodes have no -|height| or |depth| fields; these are renamed |u_part| and |v_part|, -and they point to token lists for the templates of the alignment. -For example, the |u_part| field in the first alignrecord points to the -token list `\.{u1}', i.e., the template preceding the `\.\#' for column~1. - -(2) \TeX\ now looks at what follows the \.{\\cr} that ended the preamble. -It is not `\.{\\noalign}' or `\.{\\omit}', so this input is put back to -be read again, and the template `\.{u1}' is fed to the scanner. Just -before reading `\.{u1}', \TeX\ goes into restricted horizontal mode. -Just after reading `\.{u1}', \TeX\ will see `\.{a1}', and then (when the -{\.\&} is sensed) \TeX\ will see `\.{v1}'. Then \TeX\ scans an |endv| -token, indicating the end of a column. At this point an |unset_node| is -created, containing the contents of the current hlist (i.e., `\.{u1a1v1}'). -The natural width of this unset node replaces the |width| field of the -alignrecord for column~1; in general, the alignrecords will record the -maximum natural width that has occurred so far in a given column. - -(3) Since `\.{\\omit}' follows the `\.\&', the templates for column~2 -are now bypassed. Again \TeX\ goes into restricted horizontal mode and -makes an |unset_node| from the resulting hlist; but this time the -hlist contains simply `\.{a2}'. The natural width of the new unset box -is remembered in the |width| field of the alignrecord for column~2. - -(4) A third |unset_node| is created for column 3, using essentially the -mechanism that worked for column~1; this unset box contains `\.{u3\\vrule -v3}'. The vertical rule in this case has running dimensions that will later -extend to the height and depth of the whole first row, since each |unset_node| -in a row will eventually inherit the height and depth of its enclosing box. - -(5) The first row has now ended; it is made into a single unset box -comprising the following seven items: -$$\vbox{\halign{\hbox to 325pt{\qquad\.{#}\hfil}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 1 column: u1a1v1\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 1 column: a2\cr -{}\\glue 1pt plus 1fil\cr -{}\\unsetbox for 1 column: u3\\vrule v3\cr -{}\\glue 1pt plus 1fil\cr}}$$ -The width of this unset row is unimportant, but it has the correct height -and depth, so the correct baselineskip glue will be computed as the row -is inserted into a vertical list. - -(6) Since `\.{\\noalign}' follows the current \.{\\cr}, \TeX\ appends -additional material (in this case \.{\\vskip 3pt}) to the vertical list. -While processing this material, \TeX\ will be in internal vertical -mode, and |no_align_group| will be on |save_stack|. - -(7) The next row produces an unset box that looks like this: -$$\vbox{\halign{\hbox to 325pt{\qquad\.{#}\hfil}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 2 columns: u1b1v1u2b2v2\cr -{}\\glue 1pt plus 1fil\cr -{}\\unsetbox for 1 column: {\rm(empty)}\cr -{}\\glue 1pt plus 1fil\cr}}$$ -The natural width of the unset box that spans columns 1~and~2 is stored -in a ``span node,'' which we will explain later; the |info| field of the -alignrecord for column~1 now points to the new span node, and the |info| -of the span node points to |end_span|. - -(8) The final row produces the unset box -$$\vbox{\halign{\hbox to 325pt{\qquad\.{#}\hfil}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 1 column: {\rm(empty)}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 2 columns: u2c2v2\cr -{}\\glue 1pt plus 1fil\cr}}$$ -A new span node is attached to the alignrecord for column 2. - -(9) The last step is to compute the true column widths and to change all the -unset boxes to hboxes, appending the whole works to the vertical list that -encloses the \.{\\halign}. The rules for deciding on the final widths of -each unset column box will be explained below. - -\yskip\noindent -Note that as \.{\\halign} is being processed, we fearlessly give up control -to the rest of \TeX. At critical junctures, an alignment routine is -called upon to step in and do some little action, but most of the time -these routines just lurk in the background. It's something like -post-hypnotic suggestion. - -@ We have mentioned that alignrecords contain no |height| or |depth| fields. -Their |glue_sign| and |glue_order| are pre-empted as well, since it -is necessary to store information about what to do when a template ends. -This information is called the |extra_info| field. - -@d u_part(A) mem[A+height_offset].i /*pointer to \<u_j> token list*/ -@d v_part(A) mem[A+depth_offset].i /*pointer to \<v_j> token list*/ -@d extra_info(A) info(A+list_offset) /*info to remember during template*/ - -@ Alignments can occur within alignments, so a small stack is used to access -the alignrecord information. At each level we have a |preamble| pointer, -indicating the beginning of the preamble list; a |cur_align| pointer, -indicating the current position in the preamble list; a |cur_span| pointer, -indicating the value of |cur_align| at the beginning of a sequence of -spanned columns; a |cur_loop| pointer, indicating the tabskip glue before -an alignrecord that should be copied next if the current list is extended; -and the |align_state| variable, which indicates the nesting of braces so -that \.{\\cr} and \.{\\span} and tab marks are properly intercepted. -There also are pointers |cur_head| and |cur_tail| to the head and tail -of a list of adjustments being moved out from horizontal mode to -vertical~mode. - -The current values of these seven quantities appear in global variables; -when they have to be pushed down, they are stored in 5-word nodes, and -|align_ptr| points to the topmost such node. - -@d preamble link(align_head) /*the current preamble list*/ -@d align_stack_node_size 5 /*number of |mem| words to save alignment states*/ - -@<Glob...@>= -static pointer @!cur_align; /*current position in preamble list*/ -static pointer @!cur_span; /*start of currently spanned columns in preamble list*/ -static pointer @!cur_loop; /*place to copy when extending a periodic preamble*/ -static pointer @!align_ptr; /*most recently pushed-down alignment stack node*/ -static pointer @!cur_head, @!cur_tail; /*adjustment list pointers*/ - -@ The |align_state| and |preamble| variables are initialized elsewhere. - -@<Set init...@>= -align_ptr=null;cur_align=null;cur_span=null;cur_loop=null; -cur_head=null;cur_tail=null; - -@ Alignment stack maintenance is handled by a pair of trivial routines -called |push_alignment| and |pop_alignment|. - -@p static void push_alignment(void) -{@+pointer p; /*the new alignment stack node*/ -p=get_node(align_stack_node_size); -link(p)=align_ptr;info(p)=cur_align; -llink(p)=preamble;rlink(p)=cur_span; -mem[p+2].i=cur_loop;mem[p+3].i=align_state; -info(p+4)=cur_head;link(p+4)=cur_tail; -align_ptr=p; -cur_head=get_avail(); -} -@# -static void pop_alignment(void) -{@+pointer p; /*the top alignment stack node*/ -free_avail(cur_head); -p=align_ptr; -cur_tail=link(p+4);cur_head=info(p+4); -align_state=mem[p+3].i;cur_loop=mem[p+2].i; -cur_span=rlink(p);preamble=llink(p); -cur_align=info(p);align_ptr=link(p); -free_node(p, align_stack_node_size); -} - -@ \TeX\ has eight procedures that govern alignments: |init_align| and -|fin_align| are used at the very beginning and the very end; |init_row| and -|fin_row| are used at the beginning and end of individual rows; |init_span| -is used at the beginning of a sequence of spanned columns (possibly involving -only one column); |init_col| and |fin_col| are used at the beginning and -end of individual columns; and |align_peek| is used after \.{\\cr} to see -whether the next item is \.{\\noalign}. - -We shall consider these routines in the order they are first used during -the course of a complete \.{\\halign}, namely |init_align|, |align_peek|, -|init_row|, |init_span|, |init_col|, |fin_col|, |fin_row|, |fin_align|. - -@ When \.{\\halign} or \.{\\valign} has been scanned in an appropriate -mode, \TeX\ calls |init_align|, whose task is to get everything off to a -good start. This mostly involves scanning the preamble and putting its -information into the preamble list. -@^preamble@> - -@p @t\4@>@<Declare the procedure called |get_preamble_token|@>@t@>@/ -static void align_peek(void);@/ -void normal_paragraph(void);@/ -static void init_align(void) -{@+ -pointer save_cs_ptr; /*|warning_index| value for error messages*/ -pointer @!p; /*for short-term temporary use*/ -save_cs_ptr=cur_cs; /*\.{\\halign} or \.{\\valign}, usually*/ -push_alignment();align_state=-1000000; /*enter a new alignment level*/ -@<Check for improper alignment in displayed math@>; -push_nest(); /*enter a new semantic level*/ -@<Change current mode to |-vmode| for \.{\\halign}, |-hmode| for \.{\\valign}@>; -scan_spec(align_group, false);@/ -@<Scan the preamble and record it in the |preamble| list@>; -new_save_level(align_group); -if (every_cr!=null) begin_token_list(every_cr, every_cr_text); -align_peek(); /*look for \.{\\noalign} or \.{\\omit}*/ -} - -@ In vertical modes, |prev_depth| already has the correct value. But -if we are in |mmode| (displayed formula mode), we reach out to the -enclosing vertical mode for the |prev_depth| value that produces the -correct baseline calculations. - -@<Change current mode...@>= -if (mode==mmode) - {@+mode=-vmode;prev_depth=nest[nest_ptr-2].aux_field.sc; - } -else if (mode > 0) negate(mode) - -@ When \.{\\halign} is used as a displayed formula, there should be -no other pieces of mlists present. - -@<Check for improper alignment in displayed math@>= -if ((mode==mmode)&&((tail!=head)||(incompleat_noad!=null))) - {@+print_err("Improper ");print_esc("halign");print(" inside $$'s"); -@.Improper \\halign...@> - help3("Displays can use special alignments (like \\eqalignno)",@/ - "only if nothing but the alignment itself is between $$'s.",@/ - "So I've deleted the formulas that preceded this alignment."); - error();flush_math(); - } - -@ @<Scan the preamble and record it in the |preamble| list@>= -preamble=null;cur_align=align_head;cur_loop=null;scanner_status=aligning; -warning_index=save_cs_ptr;align_state=-1000000; - /*at this point, |cur_cmd==left_brace|*/ -loop@+{@+@<Append the current tabskip glue to the preamble list@>; - if (cur_cmd==car_ret) goto done; /*\.{\\cr} ends the preamble*/ - @<Scan preamble text until |cur_cmd| is |tab_mark| or |car_ret|, looking for changes -in the tabskip glue; append an alignrecord to the preamble list@>; - } -done: scanner_status=normal - -@ @<Append the current tabskip glue to the preamble list@>= -link(cur_align)=new_param_glue(tab_skip_code); -cur_align=link(cur_align) - -@ @<Scan preamble text until |cur_cmd| is |tab_mark| or |car_ret|...@>= -@<Scan the template \<u_j>, putting the resulting token list in |hold_head|@>; -link(cur_align)=new_null_box();cur_align=link(cur_align); /*a new alignrecord*/ -info(cur_align)=end_span;width(cur_align)=null_flag; -u_part(cur_align)=link(hold_head); -@<Scan the template \<v_j>, putting the resulting token list in |hold_head|@>; -v_part(cur_align)=link(hold_head) - -@ We enter `\.{\\span}' into |eqtb| with |tab_mark| as its command code, -and with |span_code| as the command modifier. This makes \TeX\ interpret it -essentially the same as an alignment delimiter like `\.\&', yet it is -recognizably different when we need to distinguish it from a normal delimiter. -It also turns out to be useful to give a special |cr_code| to `\.{\\cr}', -and an even larger |cr_cr_code| to `\.{\\crcr}'. - -The end of a template is represented by two ``frozen'' control sequences -called \.{\\endtemplate}. The first has the command code |end_template|, which -is | > outer_call|, so it will not easily disappear in the presence of errors. -The |get_x_token| routine converts the first into the second, which has |endv| -as its command code. - -@d span_code 256 /*distinct from any character*/ -@d cr_code 257 /*distinct from |span_code| and from any character*/ -@d cr_cr_code (cr_code+1) /*this distinguishes \.{\\crcr} from \.{\\cr}*/ -@d end_template_token cs_token_flag+frozen_end_template - -@<Put each of \TeX's primitives into the hash table@>= -primitive("span", tab_mark, span_code);@/ -@!@:span\_}{\.{\\span} primitive@> -primitive("cr", car_ret, cr_code); -@!@:cr\_}{\.{\\cr} primitive@> -text(frozen_cr)=text(cur_val);eqtb[frozen_cr]=eqtb[cur_val];@/ -primitive("crcr", car_ret, cr_cr_code); -@!@:cr\_cr\_}{\.{\\crcr} primitive@> -text(frozen_end_template)=text(frozen_endv)=s_no("endtemplate"); -@.endtemplate@> -eq_type(frozen_endv)=endv;equiv(frozen_endv)=null_list; -eq_level(frozen_endv)=level_one;@/ -eqtb[frozen_end_template]=eqtb[frozen_endv]; -eq_type(frozen_end_template)=end_template; - -@ @<Cases of |print_cmd_chr|...@>= -case tab_mark: if (chr_code==span_code) print_esc("span"); - else chr_cmd("alignment tab character ")@;@+break; -case car_ret: if (chr_code==cr_code) print_esc("cr"); - else print_esc("crcr");@+break; - -@ The preamble is copied directly, except that \.{\\tabskip} causes a change -to the tabskip glue, thereby possibly expanding macros that immediately -follow it. An appearance of \.{\\span} also causes such an expansion. - -Note that if the preamble contains `\.{\\global\\tabskip}', the `\.{\\global}' -token survives in the preamble and the `\.{\\tabskip}' defines new -tabskip glue (locally). - -@<Declare the procedure called |get_preamble_token|@>= -static void get_preamble_token(void) -{@+ -restart: get_token(); -while ((cur_chr==span_code)&&(cur_cmd==tab_mark)) - {@+get_token(); /*this token will be expanded once*/ - if (cur_cmd > max_command) - {@+expand();get_token(); - } - } -if (cur_cmd==endv) - fatal_error("(interwoven alignment preambles are not allowed)"); -@.interwoven alignment preambles...@> -if ((cur_cmd==assign_glue)&&(cur_chr==glue_base+tab_skip_code)) - {@+scan_optional_equals();scan_glue(glue_val); - if (global_defs > 0) geq_define(glue_base+tab_skip_code, glue_ref, cur_val); - else eq_define(glue_base+tab_skip_code, glue_ref, cur_val); - goto restart; - } -} - -@ Spaces are eliminated from the beginning of a template. - -@<Scan the template \<u_j>...@>= -p=hold_head;link(p)=null; -loop@+{@+get_preamble_token(); - if (cur_cmd==mac_param) goto done1; - if ((cur_cmd <= car_ret)&&(cur_cmd >= tab_mark)&&(align_state==-1000000)) - if ((p==hold_head)&&(cur_loop==null)&&(cur_cmd==tab_mark) - ) cur_loop=cur_align; - else{@+print_err("Missing # inserted in alignment preamble"); -@.Missing \# inserted...@> - help3("There should be exactly one # between &'s, when an",@/ - "\\halign or \\valign is being set up. In this case you had",@/ - "none, so I've put one in; maybe that will work."); - back_error();goto done1; - } - else if ((cur_cmd!=spacer)||(p!=hold_head)) - {@+link(p)=get_avail();p=link(p);info(p)=cur_tok; - } - } -done1: - -@ @<Scan the template \<v_j>...@>= -p=hold_head;link(p)=null; -loop@+{@+resume: get_preamble_token(); - if ((cur_cmd <= car_ret)&&(cur_cmd >= tab_mark)&&(align_state==-1000000)) - goto done2; - if (cur_cmd==mac_param) - {@+print_err("Only one # is allowed per tab"); -@.Only one \# is allowed...@> - help3("There should be exactly one # between &'s, when an",@/ - "\\halign or \\valign is being set up. In this case you had",@/ - "more than one, so I'm ignoring all but the first."); - error();goto resume; - } - link(p)=get_avail();p=link(p);info(p)=cur_tok; - } -done2: link(p)=get_avail();p=link(p); -info(p)=end_template_token /*put \.{\\endtemplate} at the end*/ - -@ The tricky part about alignments is getting the templates into the -scanner at the right time, and recovering control when a row or column -is finished. - -We usually begin a row after each \.{\\cr} has been sensed, unless that -\.{\\cr} is followed by \.{\\noalign} or by the right brace that terminates -the alignment. The |align_peek| routine is used to look ahead and do -the right thing; it either gets a new row started, or gets a \.{\\noalign} -started, or finishes off the alignment. - -@<Declare the procedure called |align_peek|@>= -static void align_peek(void) -{@+ -restart: align_state=1000000; -@/do@+{get_x_or_protected(); -}@+ while (!(cur_cmd!=spacer)); -if (cur_cmd==no_align) - {@+scan_left_brace();new_save_level(no_align_group); - if (mode==-vmode) normal_paragraph(); - } -else if (cur_cmd==right_brace) fin_align(); -else if ((cur_cmd==car_ret)&&(cur_chr==cr_cr_code)) - goto restart; /*ignore \.{\\crcr}*/ -else{@+init_row(); /*start a new row*/ - init_col(); /*start a new column and replace what we peeked at*/ - } -} - -@ To start a row (i.e., a `row' that rhymes with `dough' but not with `bough'), -we enter a new semantic level, copy the first tabskip glue, and change -from internal vertical mode to restricted horizontal mode or vice versa. -The |space_factor| and |prev_depth| are not used on this semantic level, -but we clear them to zero just to be tidy. - -@p @t\4@>@<Declare the procedure called |init_span|@>@t@>@/ -static void init_row(void) -{@+push_nest();mode=(-hmode-vmode)-mode; -if (mode==-hmode) space_factor=0;@+else prev_depth=0; -tail_append(new_glue(glue_ptr(preamble))); -subtype(tail)=tab_skip_code+1;@/ -cur_align=link(preamble);cur_tail=cur_head;init_span(cur_align); -} - -@ The parameter to |init_span| is a pointer to the alignrecord where the -next column or group of columns will begin. A new semantic level is -entered, so that the columns will generate a list for subsequent packaging. - -@<Declare the procedure called |init_span|@>= -static void init_span(pointer @!p) -{@+push_nest(); -if (mode==-hmode) space_factor=1000; -else{@+prev_depth=ignore_depth;normal_paragraph(); - } -cur_span=p; -} - -@ When a column begins, we assume that |cur_cmd| is either |omit| or else -the current token should be put back into the input until the \<u_j> -template has been scanned. (Note that |cur_cmd| might be |tab_mark| or -|car_ret|.) We also assume that |align_state| is approximately 1000000 at -this time. We remain in the same mode, and start the template if it is -called for. - -@p static void init_col(void) -{@+extra_info(cur_align)=cur_cmd; -if (cur_cmd==omit) align_state=0; -else{@+back_input();begin_token_list(u_part(cur_align), u_template); - } /*now |align_state==1000000|*/ -} - -@ The scanner sets |align_state| to zero when the \<u_j> template ends. When -a subsequent \.{\\cr} or \.{\\span} or tab mark occurs with |align_state==0|, -the scanner activates the following code, which fires up the \<v_j> template. -We need to remember the |cur_chr|, which is either |cr_cr_code|, |cr_code|, -|span_code|, or a character code, depending on how the column text has ended. - -This part of the program had better not be activated when the preamble -to another alignment is being scanned, or when no alignment preamble is active. - -@<Insert the \(v)\<v_j>...@>= -{@+if ((scanner_status==aligning)||(cur_align==null)) - fatal_error("(interwoven alignment preambles are not allowed)"); -@.interwoven alignment preambles...@> -cur_cmd=extra_info(cur_align);extra_info(cur_align)=cur_chr; -if (cur_cmd==omit) begin_token_list(omit_template, v_template); -else begin_token_list(v_part(cur_align), v_template); -align_state=1000000;goto restart; -} - -@ The token list |omit_template| just referred to is a constant token -list that contains the special control sequence \.{\\endtemplate} only. - -@<Initialize the special...@>= -info(omit_template)=end_template_token; /*|link(omit_template)==null|*/ - -@ When the |endv| command at the end of a \<v_j> template comes through the -scanner, things really start to happen; and it is the |fin_col| routine -that makes them happen. This routine returns |true| if a row as well as a -column has been finished. - -@p static bool fin_col(void) -{@+ -pointer p; /*the alignrecord after the current one*/ -pointer @!q, @!r; /*temporary pointers for list manipulation*/ -pointer @!s; /*a new span node*/ -pointer @!u; /*a new unset box*/ -scaled @!w; /*natural width*/ -glue_ord @!o; /*order of infinity*/ -halfword @!n; /*span counter*/ -if (cur_align==null) confusion("endv"); -q=link(cur_align);@+if (q==null) confusion("endv"); -@:this can't happen endv}{\quad endv@> -if (align_state < 500000) - fatal_error("(interwoven alignment preambles are not allowed)"); -@.interwoven alignment preambles...@> -p=link(q); -@<If the preamble list has been traversed, check that the row has ended@>; -if (extra_info(cur_align)!=span_code) - {@+unsave();new_save_level(align_group);@/ - @<Package an unset box for the current column and record its width@>; - @<Copy the tabskip glue between columns@>; - if (extra_info(cur_align) >= cr_code) - {@+return true; - } - init_span(p); - } -align_state=1000000; -@/do@+{get_x_or_protected(); -}@+ while (!(cur_cmd!=spacer)); -cur_align=p; -init_col();return false; -} - -@ @<If the preamble list has been traversed, check that the row has ended@>= -if ((p==null)&&(extra_info(cur_align) < cr_code)) - if (cur_loop!=null) @<Lengthen the preamble periodically@>@; - else{@+print_err("Extra alignment tab has been changed to "); -@.Extra alignment tab...@> - print_esc("cr"); - help3("You have given more \\span or & marks than there were",@/ - "in the preamble to the \\halign or \\valign now in progress.",@/ - "So I'll assume that you meant to type \\cr instead."); - extra_info(cur_align)=cr_code;error(); - } - -@ @<Lengthen the preamble...@>= -{@+link(q)=new_null_box();p=link(q); /*a new alignrecord*/ -info(p)=end_span;width(p)=null_flag;cur_loop=link(cur_loop); -@<Copy the templates from node |cur_loop| into node |p|@>; -cur_loop=link(cur_loop); -link(p)=new_glue(glue_ptr(cur_loop)); -subtype(link(p))=tab_skip_code+1; -} - -@ @<Copy the templates from node |cur_loop| into node |p|@>= -q=hold_head;r=u_part(cur_loop); -while (r!=null) - {@+link(q)=get_avail();q=link(q);info(q)=info(r);r=link(r); - } -link(q)=null;u_part(p)=link(hold_head); -q=hold_head;r=v_part(cur_loop); -while (r!=null) - {@+link(q)=get_avail();q=link(q);info(q)=info(r);r=link(r); - } -link(q)=null;v_part(p)=link(hold_head) - -@ @<Copy the tabskip glue...@>= -tail_append(new_glue(glue_ptr(link(cur_align)))); -subtype(tail)=tab_skip_code+1 - -@ @<Package an unset...@>= -{@+if (mode==-hmode) - {@+adjust_tail=cur_tail;u=hpack(link(head), natural); - if (type(u)==hlist_node) w=width(u); - else w=max_dimen+1; - cur_tail=adjust_tail;adjust_tail=null; - } -else{@+u=vpackage(link(head), natural, 0); - if (type(u)==vlist_node) w=height(u); - else w=max_dimen+1; - } -n=min_quarterword; /*this represents a span count of 1*/ -if (cur_span!=cur_align) @<Update width entry for spanned columns@>@; -else if (w > width(cur_align)) width(cur_align)=w; -if (type(u)==whatsit_node) -{ if (subtype(u)==hset_node ||subtype(u)==vset_node) type(u)=unset_set_node; - else type(u)=unset_pack_node; - span_count(u)=n; -} -else if (type(u)==hlist_node ||type(u)==vlist_node) -{ type(u)=unset_node;span_count(u)=n; -@<Determine the stretch order@>; -glue_order(u)=o;glue_stretch(u)=total_stretch[o];@/ -@<Determine the shrink order@>; -glue_sign(u)=o;glue_shrink(u)=total_shrink[o];@/ -} -pop_nest();link(tail)=u;tail=u; -} - -@ A span node is a 2-word record containing |width|, |info|, and |link| -fields. The |link| field is not really a link, it indicates the number of -spanned columns; the |info| field points to a span node for the same -starting column, having a greater extent of spanning, or to |end_span|, -which has the largest possible |link| field; the |width| field holds the -largest natural width corresponding to a particular set of spanned columns. - -A list of the maximum widths so far, for spanned columns starting at a -given column, begins with the |info| field of the alignrecord for that -column. - -@d span_node_size 2 /*number of |mem| words for a span node*/ - -@<Initialize the special list heads...@>= -link(end_span)=max_quarterword+1;info(end_span)=null; - -@ @<Update width entry for spanned columns@>= -{@+q=cur_span; -@/do@+{incr(n);q=link(link(q)); -}@+ while (!(q==cur_align)); -if (n > max_quarterword) confusion("256 spans"); /*this can happen, but won't*/ -@^system dependencies@> -@:this can't happen 256 spans}{\quad 256 spans@> -q=cur_span;while (link(info(q)) < n) q=info(q); -if (link(info(q)) > n) - {@+s=get_node(span_node_size);info(s)=info(q);link(s)=n; - info(q)=s;width(s)=w; - } -else if (width(info(q)) < w) width(info(q))=w; -} - -@ At the end of a row, we append an unset box to the current vlist (for -\.{\\halign}) or the current hlist (for \.{\\valign}). This unset box -contains the unset boxes for the columns, separated by the tabskip glue. -Everything will be set later. - -@p static void fin_row(void) -{@+pointer p; /*the new unset box*/ -if (mode==-hmode) - {@+p=hpack(link(head), natural); - pop_nest();append_to_vlist(p); - if (cur_head!=cur_tail) - {@+link(tail)=link(cur_head);tail=cur_tail; - } - } -else{@+p=vpack(link(head), natural);pop_nest(); - link(tail)=p;tail=p;space_factor=1000; - } -type(p)=unset_node;glue_stretch(p)=0; -if (every_cr!=null) begin_token_list(every_cr, every_cr_text); -align_peek(); -} /*note that |glue_shrink(p)==0| since |glue_shrink====shift_amount|*/ - -@ Finally, we will reach the end of the alignment, and we can breathe a -sigh of relief that memory hasn't overflowed. All the unset boxes will now be -set so that the columns line up, taking due account of spanned columns. - -@p static void do_assignments(void);@/ -static void resume_after_display(void);@/ -extern void build_page(void); -static void fin_align(void) -{@+pointer @!p, @!q, @!r, @!s, @!u, @!v; /*registers for the list operations*/ -scaled @!t, @!w; /*width of column*/ -bool x=false; /* indicates an extende alignment */ -scaled @!o; /*shift offset for unset boxes*/ -halfword @!n; /*matching span amount*/ -scaled @!rule_save; /*temporary storage for |overfull_rule|*/ -memory_word @!aux_save; /*temporary storage for |aux|*/ -if (cur_group!=align_group) confusion("align1"); -@:this can't happen align}{\quad align@> -unsave(); /*that |align_group| was for individual entries*/ -if (cur_group!=align_group) confusion("align0"); -unsave(); /*that |align_group| was for the whole alignment*/ -if (nest[nest_ptr-1].mode_field==mmode) o=display_indent; - else o=0; -@<Go through the preamble list, determining the column widths and changing the alignrecords -to dummy unset boxes@>; -if (x) -{ @<Handle an alignment that depends on |hsize| or |vsize|@>@; - pop_alignment(); -} -else -{ @<Package the preamble list, to determine the actual tabskip glue amounts, and let - |p| point to this prototype box@>; - @<Set the glue in all the unset boxes of the current list@>; - flush_node_list(p);pop_alignment(); -} -@<Insert the \(c)current list into its environment@>; -} @/ -@t\4@>@<Declare the procedure called |align_peek|@>@; -@ @<Handle an alignment that depends on |hsize| or |vsize|@>= - pointer r=get_node(align_node_size); - save_ptr=save_ptr-2;pack_begin_line=-mode_line; - - type(r)=whatsit_node; subtype(r)=align_node; - align_preamble(r)=preamble; - align_list(r)=link(head); - align_extent(r)=new_xdimen(saved(1),saved_hfactor(1),saved_vfactor(1)); - align_m(r)= saved(0); - align_v(r)= (mode!=-vmode); - link(head)=r; tail=r; - pack_begin_line=0; - -@ It's time now to dismantle the preamble list and to compute the column -widths. Let $w_{ij}$ be the maximum of the natural widths of all entries -that span columns $i$ through $j$, inclusive. The alignrecord for column~$i$ -contains $w_{ii}$ in its |width| field, and there is also a linked list of -the nonzero $w_{ij}$ for increasing $j$, accessible via the |info| field; -these span nodes contain the value $j-i+|min_quarterword|$ in their -|link| fields. The values of $w_{ii}$ were initialized to |null_flag|, which -we regard as $-\infty$. - -The final column widths are defined by the formula -$$w_j=\max_{1\le i\le j}\biggl( w_{ij}-\sum_{i\le k<j}(t_k+w_k)\biggr),$$ -where $t_k$ is the natural width of the tabskip glue between columns -$k$ and~$k+1$. However, if $w_{ij}=-\infty$ for all |i| in the range -|1 <= i <= j| (i.e., if every entry that involved column~|j| also involved -column~|j+1|), we let $w_j=0$, and we zero out the tabskip glue after -column~|j|. - -\TeX\ computes these values by using the following scheme: First $w_1=w_{11}$. -Then replace $w_{2j}$ by $\max(w_{2j},w_{1j}-t_1-w_1)$, for all $j>1$. -Then $w_2=w_{22}$. Then replace $w_{3j}$ by $\max(w_{3j},w_{2j}-t_2-w_2)$ -for all $j>2$; and so on. If any $w_j$ turns out to be $-\infty$, its -value is changed to zero and so is the next tabskip. - -@<Go through the preamble list,...@>= -q=link(preamble); -@/do@+{flush_list(u_part(q));flush_list(v_part(q)); -p=link(link(q)); -if (width(q)==null_flag) - @<Nullify |width(q)| and the tabskip glue following this column@>; -if (info(q)!=end_span) - @<Merge the widths in the span nodes of |q| with those of |p|, destroying the span -nodes of |q|@>; -type(q)=unset_node;span_count(q)=min_quarterword;height(q)=0; -depth(q)=0;glue_order(q)=normal;glue_sign(q)=normal; -glue_stretch(q)=0;glue_shrink(q)=0;q=p; - if (width(q)>max_dimen) x=true; -}@+ while (!(q==null)) - -@ @<Nullify |width(q)| and the tabskip glue following this column@>= -{@+width(q)=0;r=link(q);s=glue_ptr(r); -if (s!=zero_glue) - {@+add_glue_ref(zero_glue);delete_glue_ref(s); - glue_ptr(r)=zero_glue; - } -} - -@ Merging of two span-node lists is a typical exercise in the manipulation of -linearly linked data structures. The essential invariant in the following -|@/do@+{| loop is that we want to dispense with node |r|, in |q|'s list, -and |u| is its successor; all nodes of |p|'s list up to and including |s| -have been processed, and the successor of |s| matches |r| or precedes |r| -or follows |r|, according as |link(r)==n| or |link(r) > n| or |link(r) < n|. - -@<Merge the widths...@>= -{@+t=width(q)+width(glue_ptr(link(q))); -r=info(q);s=end_span;info(s)=p;n=min_quarterword+1; -@/do@+{width(r)=width(r)-t;u=info(r); -while (link(r) > n) - {@+s=info(s);n=link(info(s))+1; - } -if (link(r) < n) - {@+info(r)=info(s);info(s)=r;decr(link(r));s=r; - } -else{@+if (width(r) > width(info(s))) width(info(s))=width(r); - free_node(r, span_node_size); - } -r=u; -}@+ while (!(r==end_span)); -} - -@ Now the preamble list has been converted to a list of alternating unset -boxes and tabskip glue, where the box widths are equal to the final -column sizes. In case of \.{\\valign}, we change the widths to heights, -so that a correct error message will be produced if the alignment is -overfull or underfull. - -@<Package the preamble list...@>= -save_ptr=save_ptr-2;pack_begin_line=-mode_line; -if (mode==-vmode) - {@+rule_save=overfull_rule; - overfull_rule=0; /*prevent rule from being packaged*/ - p=hpack(preamble, saved(1), saved_hfactor(1), saved_vfactor(1), saved(0));overfull_rule=rule_save; - } -else{@+q=link(preamble); - @/do@+{height(q)=width(q);width(q)=0;q=link(link(q)); - }@+ while (!(q==null)); - p=vpack(preamble, saved(1), saved_hfactor(1), saved_vfactor(1), saved(0)); - q=link(preamble); - @/do@+{width(q)=height(q);height(q)=0;q=link(link(q)); - }@+ while (!(q==null)); - } -pack_begin_line=0 - -@ @<Set the glue in all the unset...@>= -q=link(head);s=head; -while (q!=null) - {@+if (!is_char_node(q)) - if (type(q)==unset_node) - @<Set the unset box |q| and the unset boxes in it@>@; - else if (type(q)==rule_node) - @<Make the running dimensions in rule |q| extend to the boundaries of the alignment@>; - s=q;q=link(q); - } - -@ @<Make the running dimensions in rule |q| extend...@>= -{@+if (is_running(width(q))) width(q)=width(p); -if (is_running(height(q))) height(q)=height(p); -if (is_running(depth(q))) depth(q)=depth(p); -if (o!=0) - {@+r=link(q);link(q)=null;q=hpack(q, natural); - shift_amount(q)=o;link(q)=r;link(s)=q; - } -} - -@ The unset box |q| represents a row that contains one or more unset boxes, -depending on how soon \.{\\cr} occurred in that row. - -@<Set the unset box |q| and the unset boxes in it@>= -{@+if (mode==-vmode) - {@+type(q)=hlist_node;width(q)=width(p); - } -else{@+type(q)=vlist_node;height(q)=height(p); - } -glue_order(q)=glue_order(p);glue_sign(q)=glue_sign(p); -glue_set(q)=glue_set(p);shift_amount(q)=o; -r=link(list_ptr(q));s=link(list_ptr(p)); -@/do@+{@<Set the glue in node |r| and change it from an unset node@>; -r=link(link(r));s=link(link(s)); -}@+ while (!(r==null)); -} - -@ A box made from spanned columns will be followed by tabskip glue nodes and -by empty boxes as if there were no spanning. This permits perfect alignment -of subsequent entries, and it prevents values that depend on floating point -arithmetic from entering into the dimensions of any boxes. - -@<Set the glue in node |r|...@>= -n=span_count(r);t=width(s);w=t;u=hold_head; -while (n > min_quarterword) - {@+decr(n); - @<Append tabskip glue and an empty box to list |u|, and update |s| and |t| as the -prototype nodes are passed@>; - } -if (mode==-vmode) - @<Make the unset node |r| into an |hlist_node| of width |w|, setting the glue as -if the width were |t|@>@; -else@<Make the unset node |r| into a |vlist_node| of height |w|, setting the glue -as if the height were |t|@>; -shift_amount(r)=0; -if (u!=hold_head) /*append blank boxes to account for spanned nodes*/ - {@+link(u)=link(r);link(r)=link(hold_head);r=u; - } - -@ @<Append tabskip glue and an empty box to list |u|...@>= -s=link(s);v=glue_ptr(s);link(u)=new_glue(v);u=link(u); -subtype(u)=tab_skip_code+1;t=t+width(v); -if (glue_sign(p)==stretching) - {@+if (stretch_order(v)==glue_order(p)) - t=t+round(float(glue_set(p))*stretch(v)); -@^real multiplication@> - } -else if (glue_sign(p)==shrinking) - {@+if (shrink_order(v)==glue_order(p)) - t=t-round(float(glue_set(p))*shrink(v)); - } -s=link(s);link(u)=new_null_box();u=link(u);t=t+width(s); -if (mode==-vmode) width(u)=width(s);@+else - {@+type(u)=vlist_node;height(u)=width(s); - } - -@ @<Make the unset node |r| into an |hlist_node| of width |w|...@>= -{@+height(r)=height(q);depth(r)=depth(q); -if (t==width(r)) - {@+glue_sign(r)=normal;glue_order(r)=normal; - set_glue_ratio_zero(glue_set(r)); - } -else if (t > width(r)) - {@+glue_sign(r)=stretching; - if (glue_stretch(r)==0) set_glue_ratio_zero(glue_set(r)); - else glue_set(r)=unfloat((t-width(r))/(double)glue_stretch(r)); -@^real division@> - } -else{@+glue_order(r)=glue_sign(r);glue_sign(r)=shrinking; - if (glue_shrink(r)==0) set_glue_ratio_zero(glue_set(r)); - else if ((glue_order(r)==normal)&&(width(r)-t > glue_shrink(r))) - set_glue_ratio_one(glue_set(r)); - else glue_set(r)=unfloat((width(r)-t)/(double)glue_shrink(r)); - } -width(r)=w;type(r)=hlist_node; -} - -@ @<Make the unset node |r| into a |vlist_node| of height |w|...@>= -{@+width(r)=width(q); -if (t==height(r)) - {@+glue_sign(r)=normal;glue_order(r)=normal; - set_glue_ratio_zero(glue_set(r)); - } -else if (t > height(r)) - {@+glue_sign(r)=stretching; - if (glue_stretch(r)==0) set_glue_ratio_zero(glue_set(r)); - else glue_set(r)=unfloat((t-height(r))/(double)glue_stretch(r)); -@^real division@> - } -else{@+glue_order(r)=glue_sign(r);glue_sign(r)=shrinking; - if (glue_shrink(r)==0) set_glue_ratio_zero(glue_set(r)); - else if ((glue_order(r)==normal)&&(height(r)-t > glue_shrink(r))) - set_glue_ratio_one(glue_set(r)); - else glue_set(r)=unfloat((height(r)-t)/(double)glue_shrink(r)); - } -height(r)=w;type(r)=vlist_node; -} - -@ We now have a completed alignment, in the list that starts at |head| -and ends at |tail|. This list will be merged with the one that encloses -it. (In case the enclosing mode is |mmode|, for displayed formulas, -we will need to insert glue before and after the display; that part of the -program will be deferred until we're more familiar with such operations.) - -In restricted horizontal mode, the |clang| part of |aux| is undefined; -an over-cautious \PASCAL\ runtime system may complain about this. -@^dirty \PASCAL@> - -@<Insert the \(c)current list into its environment@>= -aux_save=aux;p=link(head);q=tail;pop_nest(); -if (mode==mmode) @<Finish an alignment in a display@>@; -else{@+aux=aux_save;link(tail)=p; - if (p!=null) tail=q; - if (mode==vmode) build_page(); - } - -@* Breaking paragraphs into lines. -We come now to what is probably the most interesting algorithm of \TeX: -the mechanism for choosing the ``best possible'' breakpoints that yield -the individual lines of a paragraph. \TeX's line-breaking algorithm takes -a given horizontal list and converts it to a sequence of boxes that are -appended to the current vertical list. In the course of doing this, it -creates a special data structure containing three kinds of records that are -not used elsewhere in \TeX. Such nodes are created while a paragraph is -being processed, and they are destroyed afterwards; thus, the other parts -of \TeX\ do not need to know anything about how line-breaking is done. - -The method used here is based on an approach devised by Michael F. Plass and -@^Plass, Michael Frederick@> -@^Knuth, Donald Ervin@> -the author in 1977, subsequently generalized and improved by the same two -people in 1980. A detailed discussion appears in {\sl Software---Practice -and Experience \bf11} (1981), 1119--1184, where it is shown that the -line-breaking problem can be regarded as a special case of the problem of -computing the shortest path in an acyclic network. The cited paper includes -numerous examples and describes the history of line breaking as it has been -practiced by printers through the ages. The present implementation adds two -new ideas to the algorithm of 1980: Memory space requirements are considerably -reduced by using smaller records for inactive nodes than for active ones, -and arithmetic overflow is avoided by using ``delta distances'' instead of -keeping track of the total distance from the beginning of the paragraph to the -current point. - -@ The |line_break| procedure should be invoked only in horizontal mode; it -leaves that mode and places its output into the current vlist of the -enclosing vertical mode (or internal vertical mode). -There is one explicit parameter: |final_widow_penalty| is the amount of -additional penalty to be inserted before the final line of the paragraph. - -There are also a number of implicit parameters: The hlist to be broken -starts at |link(head)|, and it is nonempty. The value of |prev_graf| in the -enclosing semantic level tells where the paragraph should begin in the -sequence of line numbers, in case hanging indentation or \.{\\parshape} -is in use; |prev_graf| is zero unless this paragraph is being continued -after a displayed formula. Other implicit parameters, such as the -|par_shape_ptr| and various penalties to use for hyphenation, etc., appear -in |eqtb|. - -After |line_break| has acted, it will have updated the current vlist and the -value of |prev_graf|. Furthermore, the global variable |just_box| will -point to the final box created by |line_break|, so that the width of this -line can be ascertained when it is necessary to decide whether to use -|above_display_skip| or |above_display_short_skip| before a displayed formula. - -@<Glob...@>= -static pointer @!just_box; /*the |hlist_node| for the last line of the new paragraph*/ - -@ Since |line_break| is a rather lengthy procedure---sort of a small world unto -itself---we must build it up little by little, somewhat more cautiously -than we have done with the simpler procedures of \TeX. Here is the -general outline. - -@p @t\4@>@<Declare subprocedures for |line_break|@>@; -void line_break(int @!final_widow_penalty) -{@+ -@<Local variables for line breaking@>@; -pack_begin_line=mode_line; /*this is for over/underfull box messages*/ -@<Get ready to start line breaking@>; -@<Find optimal breakpoints@>; -@<Break the paragraph at the chosen breakpoints, justify the resulting lines to the -correct widths, and append them to the current vertical list@>; -@<Clean up the memory by removing the break nodes@>; -pack_begin_line=0; -} -@# -@t\4@>@<Declare \eTeX\ procedures for use by |main_control|@>@; - -@ The first task is to move the list from |head| to |temp_head| and go -into the enclosing semantic level. We also append the \.{\\parfillskip} -glue to the end of the paragraph, removing a space (or other glue node) if -it was there, since spaces usually precede blank lines and instances of -`\.{\$\$}'. The |par_fill_skip| is preceded by an infinite penalty, so -it will never be considered as a potential breakpoint. - -This code assumes that a |glue_node| and a |penalty_node| occupy the -same number of |mem|~words. -@^data structure assumptions@> - -@<Get ready to start...@>= -link(temp_head)=link(head); -if (is_char_node(tail)) tail_append(new_penalty(inf_penalty))@; -else if (type(tail)!=glue_node) tail_append(new_penalty(inf_penalty))@; -else{@+type(tail)=penalty_node;delete_glue_ref(glue_ptr(tail)); - flush_node_list(leader_ptr(tail));penalty(tail)=inf_penalty; - } -link(tail)=new_param_glue(par_fill_skip_code); -init_cur_lang=prev_graf%0200000; -init_l_hyf=prev_graf/020000000; -init_r_hyf=(prev_graf/0200000)%0100; -pop_nest(); - -@ When looking for optimal line breaks, \TeX\ creates a ``break node'' for -each break that is {\sl feasible}, in the sense that there is a way to end -a line at the given place without requiring any line to stretch more than -a given tolerance. A break node is characterized by three things: the position -of the break (which is a pointer to a |glue_node|, |math_node|, |penalty_node|, -or |disc_node|); the ordinal number of the line that will follow this -breakpoint; and the fitness classification of the line that has just -ended, i.e., |tight_fit|, |decent_fit|, |loose_fit|, or |very_loose_fit|. - -@d tight_fit 3 /*fitness classification for lines shrinking 0.5 to 1.0 of their - shrinkability*/ -@d loose_fit 1 /*fitness classification for lines stretching 0.5 to 1.0 of their - stretchability*/ -@d very_loose_fit 0 /*fitness classification for lines stretching more than - their stretchability*/ -@d decent_fit 2 /*fitness classification for all other lines*/ - -@ The algorithm essentially determines the best possible way to achieve -each feasible combination of position, line, and fitness. Thus, it answers -questions like, ``What is the best way to break the opening part of the -paragraph so that the fourth line is a tight line ending at such-and-such -a place?'' However, the fact that all lines are to be the same length -after a certain point makes it possible to regard all sufficiently large -line numbers as equivalent, when the looseness parameter is zero, and this -makes it possible for the algorithm to save space and time. - -An ``active node'' and a ``passive node'' are created in |mem| for each -feasible breakpoint that needs to be considered. Active nodes are three -words long and passive nodes are two words long. We need active nodes only -for breakpoints near the place in the paragraph that is currently being -examined, so they are recycled within a comparatively short time after -they are created. - -@ An active node for a given breakpoint contains six fields: - -\yskip\hang|link| points to the next node in the list of active nodes; the -last active node has |link==last_active|. - -\yskip\hang|break_node| points to the passive node associated with this -breakpoint. - -\yskip\hang|line_number| is the number of the line that follows this -breakpoint. - -\yskip\hang|fitness| is the fitness classification of the line ending at this -breakpoint. - -\yskip\hang|type| is either |hyphenated| or |unhyphenated|, depending on -whether this breakpoint is a |disc_node|. - -\yskip\hang|total_demerits| is the minimum possible sum of demerits over all -lines leading from the beginning of the paragraph to this breakpoint. - -\yskip\noindent -The value of |link(active)| points to the first active node on a linked list -of all currently active nodes. This list is in order by |line_number|, -except that nodes with |line_number > easy_line| may be in any order relative -to each other. - -@d active_node_size 3 /*number of words in active nodes*/ -@d fitness(A) subtype(A) /*|very_loose_fit dotdot tight_fit| on final line for this break*/ -@d break_node(A) rlink(A) /*pointer to the corresponding passive node*/ -@d line_number(A) llink(A) /*line that begins at this breakpoint*/ -@d total_demerits(A) mem[A+2].i /*the quantity that \TeX\ minimizes*/ -@d unhyphenated 0 /*the |type| of a normal active break node*/ -@d hyphenated 1 /*the |type| of an active node that breaks at a |disc_node|*/ -@d last_active active /*the active list ends where it begins*/ - -@ @<Initialize the special list heads...@>= -type(last_active)=hyphenated;line_number(last_active)=max_halfword; -subtype(last_active)=0; /*the |subtype| is never examined by the algorithm*/ - -@ The passive node for a given breakpoint contains only four fields: - -\yskip\hang|link| points to the passive node created just before this one, -if any, otherwise it is |null|. - -\yskip\hang|cur_break| points to the position of this breakpoint in the -horizontal list for the paragraph being broken. - -\yskip\hang|prev_break| points to the passive node that should precede this -one in an optimal path to this breakpoint. - -\yskip\hang|serial| is equal to |n| if this passive node is the |n|th -one created during the current pass. (This field is used only when -printing out detailed statistics about the line-breaking calculations.) - -\yskip\noindent -There is a global variable called |passive| that points to the most -recently created passive node. Another global variable, |printed_node|, -is used to help print out the paragraph when detailed information about -the line-breaking computation is being displayed. - -@d passive_node_size 2 /*number of words in passive nodes*/ -@d cur_break(A) rlink(A) /*in passive node, points to position of this breakpoint*/ -@d prev_break(A) llink(A) /*points to passive node that should precede this one*/ -@d serial(A) info(A) /*serial number for symbolic identification*/ - -@<Glob...@>= -static pointer @!passive; /*most recent node on passive list*/ -static pointer @!printed_node; /*most recent node that has been printed*/ -static halfword @!pass_number; /*the number of passive nodes allocated on this pass*/ - -@ The active list also contains ``delta'' nodes that help the algorithm -compute the badness of individual lines. Such nodes appear only between two -active nodes, and they have |type==delta_node|. If |p| and |r| are active nodes -and if |q| is a delta node between them, so that |link(p)==q| and |link(q)==r|, -then |q| tells the space difference between lines in the horizontal list that -start after breakpoint |p| and lines that start after breakpoint |r|. In -other words, if we know the length of the line that starts after |p| and -ends at our current position, then the corresponding length of the line that -starts after |r| is obtained by adding the amounts in node~|q|. A delta node -contains six scaled numbers, since it must record the net change in glue -stretchability with respect to all orders of infinity. The natural width -difference appears in |mem[q+1].sc|; the stretch differences in units of -pt, fil, fill, and filll appear in |mem[q+2 dotdot q+5].sc|; and the shrink difference -appears in |mem[q+6].sc|. The |subtype| field of a delta node is not used. - -@d delta_node_size 7 /*number of words in a delta node*/ -@d delta_node 2 /*|type| field in a delta node*/ - -@ As the algorithm runs, it maintains a set of six delta-like registers -for the length of the line following the first active breakpoint to the -current position in the given hlist. When it makes a pass through the -active list, it also maintains a similar set of six registers for the -length following the active breakpoint of current interest. A third set -holds the length of an empty line (namely, the sum of \.{\\leftskip} and -\.{\\rightskip}); and a fourth set is used to create new delta nodes. - -When we pass a delta node we want to do operations like -$$\hbox{\ignorespaces|for -k=1 to 6 do cur_active_width[k]=cur_active_width[k]+mem[q+k].sc|};$$ and we -want to do this without the overhead of |for| loops. The |do_all_six| -macro makes such six-tuples convenient. - -@d do_all_six(A) A(1);A(2);A(3);A(4);A(5);A(6) - -@<Glob...@>= -static scaled @!active_width0[6], *const @!active_width = @!active_width0-1; - /*distance from first active node to~|cur_p|*/ -static scaled @!cur_active_width0[6], *const @!cur_active_width = @!cur_active_width0-1; /*distance from current active node*/ -static scaled @!background0[6], *const @!background = @!background0-1; /*length of an ``empty'' line*/ -static scaled @!break_width0[6], *const @!break_width = @!break_width0-1; /*length being computed after current break*/ - -@ Let's state the principles of the delta nodes more precisely and concisely, -so that the following programs will be less obscure. For each legal -breakpoint~|p| in the paragraph, we define two quantities $\alpha(p)$ and -$\beta(p)$ such that the length of material in a line from breakpoint~|p| -to breakpoint~|q| is $\gamma+\beta(q)-\alpha(p)$, for some fixed $\gamma$. -Intuitively, $\alpha(p)$ and $\beta(q)$ are the total length of material from -the beginning of the paragraph to a point ``after'' a break at |p| and to a -point ``before'' a break at |q|; and $\gamma$ is the width of an empty line, -namely the length contributed by \.{\\leftskip} and \.{\\rightskip}. - -Suppose, for example, that the paragraph consists entirely of alternating -boxes and glue skips; let the boxes have widths $x_1\ldots x_n$ and -let the skips have widths $y_1\ldots y_n$, so that the paragraph can be -represented by $x_1y_1\ldots x_ny_n$. Let $p_i$ be the legal breakpoint -at $y_i$; then $\alpha(p_i)=x_1+y_1+\cdots+x_i+y_i$, and $\beta(p_i)= -x_1+y_1+\cdots+x_i$. To check this, note that the length of material from -$p_2$ to $p_5$, say, is $\gamma+x_3+y_3+x_4+y_4+x_5=\gamma+\beta(p_5) --\alpha(p_2)$. - -The quantities $\alpha$, $\beta$, $\gamma$ involve glue stretchability and -shrinkability as well as a natural width. If we were to compute $\alpha(p)$ -and $\beta(p)$ for each |p|, we would need multiple precision arithmetic, and -the multiprecise numbers would have to be kept in the active nodes. -\TeX\ avoids this problem by working entirely with relative differences -or ``deltas.'' Suppose, for example, that the active list contains -$a_1\,\delta_1\,a_2\,\delta_2\,a_3$, where the |a|'s are active breakpoints -and the $\delta$'s are delta nodes. Then $\delta_1=\alpha(a_1)-\alpha(a_2)$ -and $\delta_2=\alpha(a_2)-\alpha(a_3)$. If the line breaking algorithm is -currently positioned at some other breakpoint |p|, the |active_width| array -contains the value $\gamma+\beta(p)-\alpha(a_1)$. If we are scanning through -the list of active nodes and considering a tentative line that runs from -$a_2$ to~|p|, say, the |cur_active_width| array will contain the value -$\gamma+\beta(p)-\alpha(a_2)$. Thus, when we move from $a_2$ to $a_3$, -we want to add $\alpha(a_2)-\alpha(a_3)$ to |cur_active_width|; and this -is just $\delta_2$, which appears in the active list between $a_2$ and -$a_3$. The |background| array contains $\gamma$. The |break_width| array -will be used to calculate values of new delta nodes when the active -list is being updated. - -@ Glue nodes in a horizontal list that is being paragraphed are not supposed to -include ``infinite'' shrinkability; that is why the algorithm maintains -four registers for stretching but only one for shrinking. If the user tries to -introduce infinite shrinkability, the shrinkability will be reset to finite -and an error message will be issued. A boolean variable |no_shrink_error_yet| -prevents this error message from appearing more than once per paragraph. - -@d check_shrinkage(A) if ((shrink_order(A)!=normal)&&(shrink(A)!=0)) - {@+A=finite_shrink(A); - } - -@<Glob...@>= -static bool @!no_shrink_error_yet; /*have we complained about infinite shrinkage?*/ - -@ @<Declare subprocedures for |line_break|@>= -static pointer finite_shrink(pointer @!p) /*recovers from infinite shrinkage*/ -{@+pointer q; /*new glue specification*/ -if (no_shrink_error_yet) - {@+no_shrink_error_yet=false; -#ifdef @!STAT - if (tracing_paragraphs > 0) end_diagnostic(true); -#endif -@; - print_err("Infinite glue shrinkage found in a paragraph"); -@.Infinite glue shrinkage...@> - help5("The paragraph just ended includes some glue that has",@/ - "infinite shrinkability, e.g., `\\hskip 0pt minus 1fil'.",@/ - "Such glue doesn't belong there---it allows a paragraph",@/ - "of any length to fit on one line. But it's safe to proceed,",@/ - "since the offensive shrinkability has been made finite."); - error(); -#ifdef @!STAT - if (tracing_paragraphs > 0) begin_diagnostic(); -#endif -@; - } -q=new_spec(p);shrink_order(q)=normal; -delete_glue_ref(p);return q; -} - -@ @<Get ready to start...@>= -no_shrink_error_yet=true;@/ -check_shrinkage(left_skip);check_shrinkage(right_skip);@/ -q=left_skip;r=right_skip;background[1]=width(q)+width(r);@/ -background[2]=0;background[3]=0;background[4]=0;background[5]=0;@/ -background[2+stretch_order(q)]=stretch(q);@/ -background[2+stretch_order(r)]=@|background[2+stretch_order(r)]+stretch(r);@/ -background[6]=shrink(q)+shrink(r); - -@ A pointer variable |cur_p| runs through the given horizontal list as we look -for breakpoints. This variable is global, since it is used both by |line_break| -and by its subprocedure |try_break|. - -Another global variable called |threshold| is used to determine the feasibility -of individual lines: Breakpoints are feasible if there is a way to reach -them without creating lines whose badness exceeds |threshold|. (The -badness is compared to |threshold| before penalties are added, so that -penalty values do not affect the feasibility of breakpoints, except that -no break is allowed when the penalty is 10000 or more.) If |threshold| -is 10000 or more, all legal breaks are considered feasible, since the -|badness| function specified above never returns a value greater than~10000. - -Up to three passes might be made through the paragraph in an attempt to find at -least one set of feasible breakpoints. On the first pass, we have -|threshold==pretolerance| and |second_pass==final_pass==false|. -If this pass fails to find a -feasible solution, |threshold| is set to |tolerance|, |second_pass| is set -|true|, and an attempt is made to hyphenate as many words as possible. -If that fails too, we add |emergency_stretch| to the background -stretchability and set |final_pass==true|. - -@<Glob...@>= -pointer @!cur_p; /*the current breakpoint under consideration*/ -static bool @!second_pass; /*is this our second attempt to break this paragraph?*/ -static bool @!final_pass; /*is this our final attempt to break this paragraph?*/ -static int @!threshold; /*maximum badness on feasible lines*/ - -@ The heart of the line-breaking procedure is `|try_break|', a subroutine -that tests if the current breakpoint |cur_p| is feasible, by running -through the active list to see what lines of text can be made from active -nodes to~|cur_p|. If feasible breaks are possible, new break nodes are -created. If |cur_p| is too far from an active node, that node is -deactivated. - -The parameter |pi| to |try_break| is the penalty associated -with a break at |cur_p|; we have |pi==eject_penalty| if the break is forced, -and |pi==inf_penalty| if the break is illegal. - -The other parameter, |break_type|, is set to |hyphenated| or |unhyphenated|, -depending on whether or not the current break is at a |disc_node|. The -end of a paragraph is also regarded as `|hyphenated|'; this case is -distinguishable by the condition |cur_p==null|. - -@d copy_to_cur_active(A) cur_active_width[A]=active_width[A] -@<Declare subprocedures for |line_break|@>= -static void try_break(int @!pi, small_number @!break_type) -{@+ -pointer r; /*runs through the active list*/ -pointer @!prev_r; /*stays a step behind |r|*/ -halfword @!old_l; /*maximum line number in current equivalence class of lines*/ -bool @!no_break_yet; /*have we found a feasible break at |cur_p|?*/ -@<Other local variables for |try_break|@>@; -@<Make sure that |pi| is in the proper range@>; -no_break_yet=true;prev_r=active;old_l=0; -do_all_six(copy_to_cur_active); -loop@+{@+resume: r=link(prev_r); - @<If node |r| is of type |delta_node|, update |cur_active_width|, set |prev_r| and -|prev_prev_r|, then |goto continue|@>; - @<If a line number class has ended, create new active nodes for the best feasible -breaks in that class; then |return| if |r=last_active|, otherwise compute the new -|line_width|@>; - @<Consider the demerits for a line from |r| to |cur_p|; deactivate node |r| if it -should no longer be active; then |goto continue| if a line from |r| to |cur_p| is -infeasible, otherwise record a new feasible break@>; - } -end: ; -#ifdef @!STAT -@<Update the value of |printed_node| for symbolic displays@>; -#endif -@; -} - -@ @<Other local variables for |try_break|@>= -pointer @!prev_prev_r; /*a step behind |prev_r|, if |type(prev_r)==delta_node|*/ -pointer @!s; /*runs through nodes ahead of |cur_p|*/ -pointer @!q; /*points to a new node being created*/ -pointer @!v; /*points to a glue specification or a node ahead of |cur_p|*/ -int @!t; /*node count, if |cur_p| is a discretionary node*/ -internal_font_number @!f; /*used in character width calculation*/ -halfword @!l; /*line number of current active node*/ -bool @!node_r_stays_active; /*should node |r| remain in the active list?*/ -scaled @!line_width; /*the current line will be justified to this width*/ -int @!fit_class; /*possible fitness class of test line*/ -halfword @!b; /*badness of test line*/ -int @!d; /*demerits of test line*/ -bool @!artificial_demerits; /*has |d| been forced to zero?*/ -#ifdef @!STAT -pointer @!save_link; /*temporarily holds value of |link(cur_p)|*/ -#endif -scaled @!shortfall; /*used in badness calculations*/ - -@ @<Make sure that |pi| is in the proper range@>= -if (abs(pi) >= inf_penalty) - if (pi > 0) goto end; /*this breakpoint is inhibited by infinite penalty*/ - else pi=eject_penalty /*this breakpoint will be forced*/ - -@ The following code uses the fact that |type(last_active)!=delta_node|. - -@d update_width(A) @| - cur_active_width[A]=cur_active_width[A]+mem[r+A].sc - -@<If node |r|...@>= -@^inner loop@> -if (type(r)==delta_node) - {@+do_all_six(update_width); - prev_prev_r=prev_r;prev_r=r;goto resume; - } - -@ As we consider various ways to end a line at |cur_p|, in a given line number -class, we keep track of the best total demerits known, in an array with -one entry for each of the fitness classifications. For example, -|minimal_demerits[tight_fit]| contains the fewest total demerits of feasible -line breaks ending at |cur_p| with a |tight_fit| line; |best_place[tight_fit]| -points to the passive node for the break before~|cur_p| that achieves such -an optimum; and |best_pl_line[tight_fit]| is the |line_number| field in the -active node corresponding to |best_place[tight_fit]|. When no feasible break -sequence is known, the |minimal_demerits| entries will be equal to -|awful_bad|, which is $2^{30}-1$. Another variable, |minimum_demerits|, -keeps track of the smallest value in the |minimal_demerits| array. - -@d awful_bad 07777777777 /*more than a billion demerits*/ - -@<Global...@>= -static int @!minimal_demerits0[tight_fit-very_loose_fit+1], *const @!minimal_demerits = @!minimal_demerits0-very_loose_fit; /*best total - demerits known for current line class and position, given the fitness*/ -static int @!minimum_demerits; /*best total demerits known for current line class - and position*/ -static pointer @!best_place0[tight_fit-very_loose_fit+1], *const @!best_place = @!best_place0-very_loose_fit; /*how to achieve - |minimal_demerits|*/ -static halfword @!best_pl_line0[tight_fit-very_loose_fit+1], *const @!best_pl_line = @!best_pl_line0-very_loose_fit; /*corresponding - line number*/ - -@ @<Get ready to start...@>= -minimum_demerits=awful_bad; -minimal_demerits[tight_fit]=awful_bad; -minimal_demerits[decent_fit]=awful_bad; -minimal_demerits[loose_fit]=awful_bad; -minimal_demerits[very_loose_fit]=awful_bad; - -@ The first part of the following code is part of \TeX's inner loop, so -we don't want to waste any time. The current active node, namely node |r|, -contains the line number that will be considered next. At the end of the -list we have arranged the data structure so that |r==last_active| and -|line_number(last_active) > old_l|. -@^inner loop@> - -@<If a line number class...@>= -{@+l=line_number(r); -if (l > old_l) - {@+ /*now we are no longer in the inner loop*/ - if ((minimum_demerits < awful_bad)&&@| - ((old_l!=easy_line)||(r==last_active))) - @<Create new active nodes for the best feasible breaks just found@>; - if (r==last_active) goto end; - @<Compute the new line width@>; - } -} - -@ It is not necessary to create new active nodes having |minimal_demerits| -greater than -|minimum_demerits+abs(adj_demerits)|, since such active nodes will never -be chosen in the final paragraph breaks. This observation allows us to -omit a substantial number of feasible breakpoints from further consideration. - -@<Create new active nodes...@>= -{@+if (no_break_yet) @<Compute the values of |break_width|@>; -@<Insert a delta node to prepare for breaks at |cur_p|@>; -if (abs(adj_demerits) >= awful_bad-minimum_demerits) - minimum_demerits=awful_bad-1; -else minimum_demerits=minimum_demerits+abs(adj_demerits); -for (fit_class=very_loose_fit; fit_class<=tight_fit; fit_class++) - {@+if (minimal_demerits[fit_class] <= minimum_demerits) - @<Insert a new active node from |best_place[fit_class]| to |cur_p|@>; - minimal_demerits[fit_class]=awful_bad; - } -minimum_demerits=awful_bad; -@<Insert a delta node to prepare for the next active node@>; -} - -@ When we insert a new active node for a break at |cur_p|, suppose this -new node is to be placed just before active node |a|; then we essentially -want to insert `$\delta\,|cur_p|\,\delta^\prime$' before |a|, where -$\delta=\alpha(a)-\alpha(|cur_p|)$ and $\delta^\prime=\alpha(|cur_p|)-\alpha(a)$ -in the notation explained above. The |cur_active_width| array now holds -$\gamma+\beta(|cur_p|)-\alpha(a)$; so $\delta$ can be obtained by -subtracting |cur_active_width| from the quantity $\gamma+\beta(|cur_p|)- -\alpha(|cur_p|)$. The latter quantity can be regarded as the length of a -line ``from |cur_p| to |cur_p|''; we call it the |break_width| at |cur_p|. - -The |break_width| is usually negative, since it consists of the background -(which is normally zero) minus the width of nodes following~|cur_p| that are -eliminated after a break. If, for example, node |cur_p| is a glue node, the -width of this glue is subtracted from the background; and we also look -ahead to eliminate all subsequent glue and penalty and kern and math -nodes, subtracting their widths as well. - -Kern nodes do not disappear at a line break unless they are |explicit|. - -@d set_break_width_to_background(A) break_width[A]=background[A] - -@<Compute the values of |break...@>= -{@+no_break_yet=false;do_all_six(set_break_width_to_background); -s=cur_p; -if (break_type > unhyphenated) if (cur_p!=null) - @<Compute the discretionary |break_width| values@>; -while (s!=null) - {@+if (is_char_node(s)) goto done; - switch (type(s)) { - case glue_node: @<Subtract glue from |break_width|@>@;@+break; - case penalty_node: do_nothing;@+break; - case math_node: break_width[1]=break_width[1]-width(s);@+break; - case kern_node: if (subtype(s)!=explicit) goto done; - else break_width[1]=break_width[1]-width(s);@+break; - default:goto done; - } @/ - s=link(s); - } -done: ;} - -@ @<Subtract glue from |break...@>= -{@+v=glue_ptr(s);break_width[1]=break_width[1]-width(v); -break_width[2+stretch_order(v)]=break_width[2+stretch_order(v)]-stretch(v); -break_width[6]=break_width[6]-shrink(v); -} - -@ When |cur_p| is a discretionary break, the length of a line ``from |cur_p| to -|cur_p|'' has to be defined properly so that the other calculations work out. -Suppose that the pre-break text at |cur_p| has length $l_0$, the post-break -text has length $l_1$, and the replacement text has length |l|. Suppose -also that |q| is the node following the replacement text. Then length of a -line from |cur_p| to |q| will be computed as $\gamma+\beta(q)-\alpha(|cur_p|)$, -where $\beta(q)=\beta(|cur_p|)-l_0+l$. The actual length will be the background -plus $l_1$, so the length from |cur_p| to |cur_p| should be $\gamma+l_0+l_1-l$. -If the post-break text of the discretionary is empty, a break may also -discard~|q|; in that unusual case we subtract the length of~|q| and any -other nodes that will be discarded after the discretionary break. - -The value of $l_0$ need not be computed, since |line_break| will put -it into the global variable |disc_width| before calling |try_break|. - -@<Glob...@>= -static scaled @!disc_width; /*the length of discretionary material preceding a break*/ - -@ @<Compute the discretionary |break...@>= -{@+t=replace_count(cur_p);v=cur_p;s=post_break(cur_p); -while (t > 0) - {@+decr(t);v=link(v); - @<Subtract the width of node |v| from |break_width|@>; - } -while (s!=null) - {@+@<Add the width of node |s| to |break_width|@>; - s=link(s); - } -break_width[1]=break_width[1]+disc_width; -if (post_break(cur_p)==null) s=link(v); - /*nodes may be discardable after the break*/ -} - -@ Replacement texts and discretionary texts are supposed to contain -only character nodes, kern nodes, ligature nodes, and box or rule nodes. - -@<Subtract the width of node |v|...@>= -if (is_char_node(v)) - {@+f=font(v); - break_width[1]=break_width[1]-char_width(f, char_info(f, character(v))); - } -else switch (type(v)) { - case ligature_node: {@+f=font(lig_char(v));@/ - break_width[1]=@|break_width[1]- - char_width(f, char_info(f, character(lig_char(v)))); - } @+break; - case hlist_node: case vlist_node: case rule_node: case kern_node: - break_width[1]=break_width[1]-width(v);@+break; - default:confusion("disc1"); -@:this can't happen disc1}{\quad disc1@> - } - -@ @<Add the width of node |s| to |b...@>= -if (is_char_node(s)) - {@+f=font(s); - break_width[1]=@|break_width[1]+char_width(f, char_info(f, character(s))); - } -else switch (type(s)) { - case ligature_node: {@+f=font(lig_char(s)); - break_width[1]=break_width[1]+ - char_width(f, char_info(f, character(lig_char(s)))); - } @+break; - case hlist_node: case vlist_node: case rule_node: case kern_node: - break_width[1]=break_width[1]+width(s);@+break; - default:confusion("disc2"); -@:this can't happen disc2}{\quad disc2@> - } - -@ We use the fact that |type(active)!=delta_node|. - -@d convert_to_break_width(A) @| - mem[prev_r+A].sc=@|@t\hskip10pt@>mem[prev_r+A].sc - -cur_active_width[A]+break_width[A] -@d store_break_width(A) active_width[A]=break_width[A] -@d new_delta_to_break_width(A) @| - mem[q+A].sc=break_width[A]-cur_active_width[A] - -@<Insert a delta node to prepare for breaks at |cur_p|@>= -if (type(prev_r)==delta_node) /*modify an existing delta node*/ - {@+do_all_six(convert_to_break_width); - } -else if (prev_r==active) /*no delta node needed at the beginning*/ - {@+do_all_six(store_break_width); - } -else{@+q=get_node(delta_node_size);link(q)=r;type(q)=delta_node;@/ - subtype(q)=0; /*the |subtype| is not used*/ - do_all_six(new_delta_to_break_width); - link(prev_r)=q;prev_prev_r=prev_r;prev_r=q; - } - -@ When the following code is performed, we will have just inserted at -least one active node before |r|, so |type(prev_r)!=delta_node|. - -@d new_delta_from_break_width(A) @|mem[q+A].sc= - cur_active_width[A]-break_width[A] - -@<Insert a delta node to prepare for the next active node@>= -if (r!=last_active) - {@+q=get_node(delta_node_size);link(q)=r;type(q)=delta_node;@/ - subtype(q)=0; /*the |subtype| is not used*/ - do_all_six(new_delta_from_break_width); - link(prev_r)=q;prev_prev_r=prev_r;prev_r=q; - } - -@ When we create an active node, we also create the corresponding -passive node. - -@<Insert a new active node from |best_place[fit_class]| to |cur_p|@>= -{@+q=get_node(passive_node_size); -link(q)=passive;passive=q;cur_break(q)=cur_p; -#ifdef @!STAT -incr(pass_number);serial(q)=pass_number; -#endif -@;@/ -prev_break(q)=best_place[fit_class];@/ -q=get_node(active_node_size);break_node(q)=passive; -line_number(q)=best_pl_line[fit_class]+1; -fitness(q)=fit_class;type(q)=break_type; -total_demerits(q)=minimal_demerits[fit_class]; -link(q)=r;link(prev_r)=q;prev_r=q; -#ifdef @!STAT -if (tracing_paragraphs > 0) - @<Print a symbolic description of the new break node@>; -#endif -@;@/ -} - -@ @<Print a symbolic description of the new break node@>= -{@+print_nl("@@@@");print_int(serial(passive)); -@.\AT\AT@> -print(": line ");print_int(line_number(q)-1); -print_char('.');print_int(fit_class); -if (break_type==hyphenated) print_char('-'); -print(" t=");print_int(total_demerits(q)); -print(" -> @@@@"); -if (prev_break(passive)==null) print_char('0'); -else print_int(serial(prev_break(passive))); -} - -@ The length of lines depends on whether the user has specified -\.{\\parshape} or \.{\\hangindent}. If |par_shape_ptr| is not null, it -points to a $(2n+1)$-word record in |mem|, where the |info| in the first -word contains the value of |n|, and the other $2n$ words contain the left -margins and line lengths for the first |n| lines of the paragraph; the -specifications for line |n| apply to all subsequent lines. If -|par_shape_ptr==null|, the shape of the paragraph depends on the value of -|n==hang_after|; if |n >= 0|, hanging indentation takes place on lines |n+1|, -|n+2|, \dots, otherwise it takes place on lines 1, \dots, $\vert -n\vert$. When hanging indentation is active, the left margin is -|hang_indent|, if |hang_indent >= 0|, else it is 0; the line length is -$|hsize|-\vert|hang_indent|\vert$. The normal setting is -|par_shape_ptr==null|, |hang_after==1|, and |hang_indent==0|. -Note that if |hang_indent==0|, the value of |hang_after| is irrelevant. -@^length of lines@> @^hanging indentation@> - -@<Glob...@>= -static halfword @!easy_line; /*line numbers | > easy_line| are equivalent in break nodes*/ -halfword @!last_special_line; /*line numbers | > last_special_line| all have - the same width*/ -static scaled @!first_width; /*the width of all lines | <= last_special_line|, if - no \.{\\parshape} has been specified*/ -scaled @!second_width; /*the width of all lines | > last_special_line|*/ -static scaled @!first_indent; /*left margin to go with |first_width|*/ -scaled @!second_indent; /*left margin to go with |second_width|*/ - -@ We compute the values of |easy_line| and the other local variables relating -to line length when the |line_break| procedure is initializing itself. - -@<Get ready to start...@>= -if (par_shape_ptr==null) - if (hang_indent==0) - {@+last_special_line=0;second_width=hsize; - second_indent=0; - } - else@<Set line length parameters in preparation for hanging indentation@>@; -else{@+last_special_line=info(par_shape_ptr)-1; - second_width=mem[par_shape_ptr+2*(last_special_line+1)].sc; - second_indent=mem[par_shape_ptr+2*last_special_line+1].sc; - } -if (looseness==0) easy_line=last_special_line; -else easy_line=max_halfword - -@ @<Set line length parameters in preparation for hanging indentation@>= -{@+last_special_line=abs(hang_after); -if (hang_after < 0) - {@+first_width=hsize-abs(hang_indent); - if (hang_indent >= 0) first_indent=hang_indent; - else first_indent=0; - second_width=hsize;second_indent=0; - } -else{@+first_width=hsize;first_indent=0; - second_width=hsize-abs(hang_indent); - if (hang_indent >= 0) second_indent=hang_indent; - else second_indent=0; - } -} - -@ When we come to the following code, we have just encountered the first -active node~|r| whose |line_number| field contains |l|. Thus we want to -compute the length of the $l\mskip1mu$th line of the current paragraph. Furthermore, -we want to set |old_l| to the last number in the class of line numbers -equivalent to~|l|. - -@<Compute the new line width@>= -if (l > easy_line) - {@+line_width=second_width;old_l=max_halfword-1; - } -else{@+old_l=l; - if (l > last_special_line) line_width=second_width; - else if (par_shape_ptr==null) line_width=first_width; - else line_width=mem[par_shape_ptr+2*l@,].sc; - } - -@ The remaining part of |try_break| deals with the calculation of -demerits for a break from |r| to |cur_p|. - -The first thing to do is calculate the badness, |b|. This value will always -be between zero and |inf_bad+1|; the latter value occurs only in the -case of lines from |r| to |cur_p| that cannot shrink enough to fit the necessary -width. In such cases, node |r| will be deactivated. -We also deactivate node~|r| when a break at~|cur_p| is forced, since future -breaks must go through a forced break. - -@<Consider the demerits for a line from |r| to |cur_p|...@>= -{@+artificial_demerits=false;@/ -@^inner loop@> -shortfall=line_width-cur_active_width[1]; /*we're this much too short*/ -if (shortfall > 0) - @<Set the value of |b| to the badness for stretching the line, and compute the corresponding -|fit_class|@>@; -else@<Set the value of |b| to the badness for shrinking the line, and compute the -corresponding |fit_class|@>; -if ((b > inf_bad)||(pi==eject_penalty)) - @<Prepare to deactivate node~|r|, and |goto deactivate| unless there is a reason -to consider lines of text from |r| to |cur_p|@>@; -else{@+prev_r=r; - if (b > threshold) goto resume; - node_r_stays_active=true; - } -@<Record a new feasible break@>; -if (node_r_stays_active) goto resume; /*|prev_r| has been set to |r|*/ -deactivate: @<Deactivate node |r|@>; -} - -@ When a line must stretch, the available stretchability can be found in the -subarray |cur_active_width[2 dotdot 5]|, in units of points, fil, fill, and filll. - -The present section is part of \TeX's inner loop, and it is most often performed -when the badness is infinite; therefore it is worth while to make a quick -test for large width excess and small stretchability, before calling the -|badness| subroutine. -@^inner loop@> - -@<Set the value of |b| to the badness for stretching...@>= -if ((cur_active_width[3]!=0)||(cur_active_width[4]!=0)||@| - (cur_active_width[5]!=0)) - {@+b=0;fit_class=decent_fit; /*infinite stretch*/ - } -else{@+if (shortfall > 7230584) if (cur_active_width[2] < 1663497) - {@+b=inf_bad;fit_class=very_loose_fit;goto done1; - } - b=badness(shortfall, cur_active_width[2]); - if (b > 12) - if (b > 99) fit_class=very_loose_fit; - else fit_class=loose_fit; - else fit_class=decent_fit; - done1: ; - } - -@ Shrinkability is never infinite in a paragraph; -we can shrink the line from |r| to |cur_p| by at most |cur_active_width[6]|. - -@<Set the value of |b| to the badness for shrinking...@>= -{@+if (-shortfall > cur_active_width[6]) b=inf_bad+1; -else b=badness(-shortfall, cur_active_width[6]); -if (b > 12) fit_class=tight_fit;@+else fit_class=decent_fit; -} - -@ During the final pass, we dare not lose all active nodes, lest we lose -touch with the line breaks already found. The code shown here makes sure -that such a catastrophe does not happen, by permitting overfull boxes as -a last resort. This particular part of \TeX\ was a source of several subtle -bugs before the correct program logic was finally discovered; readers -who seek to ``improve'' \TeX\ should therefore think thrice before daring -to make any changes here. -@^overfull boxes@> - -@<Prepare to deactivate node~|r|, and |goto deactivate| unless...@>= -{@+if (final_pass&&(minimum_demerits==awful_bad)&&@| - (link(r)==last_active)&& - (prev_r==active)) - artificial_demerits=true; /*set demerits zero, this break is forced*/ -else if (b > threshold) goto deactivate; -node_r_stays_active=false; -} - -@ When we get to this part of the code, the line from |r| to |cur_p| is -feasible, its badness is~|b|, and its fitness classification is |fit_class|. -We don't want to make an active node for this break yet, but we will -compute the total demerits and record them in the |minimal_demerits| array, -if such a break is the current champion among all ways to get to |cur_p| -in a given line-number class and fitness class. - -@<Record a new feasible break@>= -if (artificial_demerits) d=0; -else@<Compute the demerits, |d|, from |r| to |cur_p|@>; -#ifdef @!STAT -if (tracing_paragraphs > 0) - @<Print a symbolic description of this feasible break@>; -#endif -@;@/ -d=d+total_demerits(r); /*this is the minimum total demerits - from the beginning to |cur_p| via |r|*/ -if (d <= minimal_demerits[fit_class]) - {@+minimal_demerits[fit_class]=d; - best_place[fit_class]=break_node(r);best_pl_line[fit_class]=l; - if (d < minimum_demerits) minimum_demerits=d; - } - -@ @<Print a symbolic description of this feasible break@>= -{@+if (printed_node!=cur_p) - @<Print the list between |printed_node| and |cur_p|, then set |printed_node:=cur_p|@>; -print_nl("@@"); -@.\AT@> -if (cur_p==null) print_esc("par"); -else if (type(cur_p)!=glue_node) - {@+if (type(cur_p)==penalty_node) print_esc("penalty"); - else if (type(cur_p)==disc_node) print_esc("discretionary"); - else if (type(cur_p)==kern_node) print_esc("kern"); - else print_esc("math"); - } -print(" via @@@@"); -if (break_node(r)==null) print_char('0'); -else print_int(serial(break_node(r))); -print(" b="); -if (b > inf_bad) print_char('*');@+else print_int(b); -@.*\relax@> -print(" p=");print_int(pi);print(" d="); -if (artificial_demerits) print_char('*');@+else print_int(d); -} - -@ @<Print the list between |printed_node| and |cur_p|...@>= -{@+print_nl(""); -if (cur_p==null) short_display(link(printed_node)); -else{@+save_link=link(cur_p); - link(cur_p)=null;print_nl("");short_display(link(printed_node)); - link(cur_p)=save_link; - } -printed_node=cur_p; -} - -@ When the data for a discretionary break is being displayed, we will have -printed the |pre_break| and |post_break| lists; we want to skip over the -third list, so that the discretionary data will not appear twice. The -following code is performed at the very end of |try_break|. - -@<Update the value of |printed_node|...@>= -if (cur_p==printed_node) if (cur_p!=null) if (type(cur_p)==disc_node) - {@+t=replace_count(cur_p); - while (t > 0) - {@+decr(t);printed_node=link(printed_node); - } - } - -@ @<Compute the demerits, |d|, from |r| to |cur_p|@>= -{@+d=line_penalty+b; -if (abs(d) >= 10000) d=100000000;@+else d=d*d; -if (pi!=0) - if (pi > 0) d=d+pi*pi; - else if (pi > eject_penalty) d=d-pi*pi; -if ((break_type==hyphenated)&&(type(r)==hyphenated)) - if (cur_p!=null) d=d+double_hyphen_demerits; - else d=d+final_hyphen_demerits; -if (abs(fit_class-fitness(r)) > 1) d=d+adj_demerits; -} - -@ When an active node disappears, we must delete an adjacent delta node if the -active node was at the beginning or the end of the active list, or if it -was surrounded by delta nodes. We also must preserve the property that -|cur_active_width| represents the length of material from |link(prev_r)| -to~|cur_p|. - -@d combine_two_deltas(A) @|mem[prev_r+A].sc=mem[prev_r+A].sc+mem[r+A].sc -@d downdate_width(A) @|cur_active_width[A]=cur_active_width[A]- - mem[prev_r+A].sc - -@<Deactivate node |r|@>= -link(prev_r)=link(r);free_node(r, active_node_size); -if (prev_r==active) @<Update the active widths, since the first active node has been -deleted@>@; -else if (type(prev_r)==delta_node) - {@+r=link(prev_r); - if (r==last_active) - {@+do_all_six(downdate_width); - link(prev_prev_r)=last_active; - free_node(prev_r, delta_node_size);prev_r=prev_prev_r; - } - else if (type(r)==delta_node) - {@+do_all_six(update_width); - do_all_six(combine_two_deltas); - link(prev_r)=link(r);free_node(r, delta_node_size); - } - } - -@ The following code uses the fact that |type(last_active)!=delta_node|. If the -active list has just become empty, we do not need to update the -|active_width| array, since it will be initialized when an active -node is next inserted. - -@d update_active(A) active_width[A]=active_width[A]+mem[r+A].sc - -@<Update the active widths,...@>= -{@+r=link(active); -if (type(r)==delta_node) - {@+do_all_six(update_active); - do_all_six(copy_to_cur_active); - link(active)=link(r);free_node(r, delta_node_size); - } -} - -@* Breaking paragraphs into lines, continued. -So far we have gotten a little way into the |line_break| routine, having -covered its important |try_break| subroutine. Now let's consider the -rest of the process. - -The main loop of |line_break| traverses the given hlist, -starting at |link(temp_head)|, and calls |try_break| at each legal -breakpoint. A variable called |auto_breaking| is set to true except -within math formulas, since glue nodes are not legal breakpoints when -they appear in formulas. - -The current node of interest in the hlist is pointed to by |cur_p|. Another -variable, |prev_p|, is usually one step behind |cur_p|, but the real -meaning of |prev_p| is this: If |type(cur_p)==glue_node| then |cur_p| is a legal -breakpoint if and only if |auto_breaking| is true and |prev_p| does not -point to a glue node, penalty node, explicit kern node, or math node. - -The following declarations provide for a few other local variables that are -used in special calculations. - -@<Local variables for line breaking@>= -bool @!auto_breaking; /*is node |cur_p| outside a formula?*/ -pointer @!prev_p; /*helps to determine when glue nodes are breakpoints*/ -pointer @!q, @!r, @!s, @!prev_s; /*miscellaneous nodes of temporary interest*/ -internal_font_number @!f; /*used when calculating character widths*/ - -@ The `\ignorespaces|loop|\unskip' in the following code is performed at most -thrice per call of |line_break|, since it is actually a pass over the -entire paragraph. - -@<Find optimal breakpoints@>= -threshold=pretolerance; -if (threshold >= 0) - { -#ifdef @!STAT -if (tracing_paragraphs > 0) - {@+begin_diagnostic();print_nl("@@firstpass");@+} @; -#endif -@;@/ - second_pass=false;final_pass=false; - } -else{@+threshold=tolerance;second_pass=true; - final_pass=(emergency_stretch <= 0); -#ifdef @!STAT - if (tracing_paragraphs > 0) begin_diagnostic(); -#endif -@; - } -loop@+{@+if (threshold > inf_bad) threshold=inf_bad; - if (second_pass) @<Initialize for hyphenating a paragraph@>; - @<Create an active breakpoint representing the beginning of the paragraph@>; - cur_p=link(temp_head);auto_breaking=true;@/ - prev_p=cur_p; /*glue at beginning is not a legal breakpoint*/ - while ((cur_p!=null)&&(link(active)!=last_active)) - @<Call |try_break| if |cur_p| is a legal breakpoint; on the second pass, also -try to hyphenate the next word, if |cur_p| is a glue node; then advance |cur_p| to -the next node of the paragraph that could possibly be a legal breakpoint@>; - if (cur_p==null) - @<Try the final line break at the end of the paragraph, and |goto done| if the -desired breakpoints have been found@>; - @<Clean up the memory by removing the break nodes@>; - if (!second_pass) - { -#ifdef @!STAT -if (tracing_paragraphs > 0) print_nl("@@secondpass");@; -#endif - threshold=tolerance;second_pass=true;final_pass=(emergency_stretch <= 0); - } /*if at first you don't succeed, \dots*/ - else{ -#ifdef @!STAT -if (tracing_paragraphs > 0) - print_nl("@@emergencypass");@; -#endif - background[2]=background[2]+emergency_stretch;final_pass=true; - } - } -done: -#ifdef @!STAT -if (tracing_paragraphs > 0) - {@+end_diagnostic(true);normalize_selector(); - } -#endif - -@ The active node that represents the starting point does not need a -corresponding passive node. - -@d store_background(A) active_width[A]=background[A] - -@<Create an active breakpoint representing the beginning of the paragraph@>= -q=get_node(active_node_size); -type(q)=unhyphenated;fitness(q)=decent_fit; -link(q)=last_active;break_node(q)=null; -line_number(q)=prev_graf+1;total_demerits(q)=0;link(active)=q; -do_all_six(store_background);@/ -passive=null;printed_node=temp_head;pass_number=0; -font_in_short_display=null_font - -@ @<Clean...@>= -q=link(active); -while (q!=last_active) - {@+cur_p=link(q); - if (type(q)==delta_node) free_node(q, delta_node_size); - else free_node(q, active_node_size); - q=cur_p; - } -q=passive; -while (q!=null) - {@+cur_p=link(q); - free_node(q, passive_node_size); - q=cur_p; - } - -@ Here is the main switch in the |line_break| routine, where legal breaks -are determined. As we move through the hlist, we need to keep the |active_width| -array up to date, so that the badness of individual lines is readily calculated -by |try_break|. It is convenient to use the short name |act_width| for -the component of active width that represents real width as opposed to glue. - -@d act_width active_width[1] /*length from first active node to current node*/ -@d kern_break {@+if (!is_char_node(link(cur_p))&&auto_breaking) - if (type(link(cur_p))==glue_node) try_break(0, unhyphenated); - act_width=act_width+width(cur_p); - } - -@<Call |try_break| if |cur_p| is a legal breakpoint...@>= -{@+if (is_char_node(cur_p)) - @<Advance \(c)|cur_p| to the node following the present string of characters@>; -switch (type(cur_p)) { -case hlist_node: case vlist_node: case rule_node: act_width=act_width+width(cur_p);@+break; -case whatsit_node: @<Advance \(p)past a whatsit node in the \(l)|line_break| loop@>@;@+break; -case glue_node: {@+@<If node |cur_p| is a legal breakpoint, call |try_break|; then -update the active widths by including the glue in |glue_ptr(cur_p)|@>; - if (second_pass&&auto_breaking) - hyphenate_word(); - } @+break; -case kern_node: if (subtype(cur_p)==explicit) kern_break@; - else act_width=act_width+width(cur_p);@+break; -case ligature_node: {@+f=font(lig_char(cur_p)); - act_width=act_width+char_width(f, char_info(f, character(lig_char(cur_p)))); - } @+break; -case disc_node: @<Try to break after a discretionary fragment, then |goto done5|@>@; -case math_node: {@+auto_breaking=(subtype(cur_p)==after);kern_break; - } @+break; -case penalty_node: try_break(penalty(cur_p), unhyphenated);@+break; -case mark_node: case ins_node: case adjust_node: do_nothing;@+break; -default:confusion("paragraph"); -@:this can't happen paragraph}{\quad paragraph@> -} @/ -prev_p=cur_p;cur_p=link(cur_p); -done5: ;} - -@ The code that passes over the characters of words in a paragraph is -part of \TeX's inner loop, so it has been streamlined for speed. We use -the fact that `\.{\\parfillskip}' glue appears at the end of each paragraph; -it is therefore unnecessary to check if |link(cur_p)==null| when |cur_p| is a -character node. -@^inner loop@> - -@<Advance \(c)|cur_p| to the node following the present string...@>= -{@+prev_p=cur_p; -@/do@+{f=font(cur_p); -act_width=act_width+char_width(f, char_info(f, character(cur_p))); -cur_p=link(cur_p); -}@+ while (!(!is_char_node(cur_p))); -} - -@ When node |cur_p| is a glue node, we look at |prev_p| to see whether or not -a breakpoint is legal at |cur_p|, as explained above. - -@<If node |cur_p| is a legal breakpoint, call...@>= -if (auto_breaking) - {@+if (is_char_node(prev_p)) try_break(0, unhyphenated); - else if (precedes_break(prev_p)) try_break(0, unhyphenated); - else if ((type(prev_p)==kern_node)&&(subtype(prev_p)!=explicit)) - try_break(0, unhyphenated); - } -check_shrinkage(glue_ptr(cur_p));q=glue_ptr(cur_p); -act_width=act_width+width(q);@| -active_width[2+stretch_order(q)]=@| - active_width[2+stretch_order(q)]+stretch(q);@/ -active_width[6]=active_width[6]+shrink(q) - -@ The following code knows that discretionary texts contain -only character nodes, kern nodes, box nodes, rule nodes, and ligature nodes. - -@<Try to break after a discretionary fragment...@>= -{@+s=pre_break(cur_p);disc_width=0; -if (s==null) try_break(ex_hyphen_penalty, hyphenated); -else{@+@/do@+{@<Add the width of node |s| to |disc_width|@>; - s=link(s); - }@+ while (!(s==null)); - act_width=act_width+disc_width; - try_break(hyphen_penalty, hyphenated); - act_width=act_width-disc_width; - } -r=replace_count(cur_p);s=link(cur_p); -while (r > 0) - {@+@<Add the width of node |s| to |act_width|@>; - decr(r);s=link(s); - } -prev_p=cur_p;cur_p=s;goto done5; -} - -@ @<Add the width of node |s| to |disc_width|@>= -if (is_char_node(s)) - {@+f=font(s); - disc_width=disc_width+char_width(f, char_info(f, character(s))); - } -else switch (type(s)) { - case ligature_node: {@+f=font(lig_char(s)); - disc_width=disc_width+ - char_width(f, char_info(f, character(lig_char(s)))); - } @+break; - case hlist_node: case vlist_node: case rule_node: case kern_node: - disc_width=disc_width+width(s);@+break; - default:confusion("disc3"); -@:this can't happen disc3}{\quad disc3@> - } - -@ @<Add the width of node |s| to |act_width|@>= -if (is_char_node(s)) - {@+f=font(s); - act_width=act_width+char_width(f, char_info(f, character(s))); - } -else switch (type(s)) { - case ligature_node: {@+f=font(lig_char(s)); - act_width=act_width+ - char_width(f, char_info(f, character(lig_char(s)))); - } @+break; - case hlist_node: case vlist_node: case rule_node: case kern_node: - act_width=act_width+width(s);@+break; - default:confusion("disc4"); -@:this can't happen disc4}{\quad disc4@> - } - -@ The forced line break at the paragraph's end will reduce the list of -breakpoints so that all active nodes represent breaks at |cur_p==null|. -On the first pass, we insist on finding an active node that has the -correct ``looseness.'' On the final pass, there will be at least one active -node, and we will match the desired looseness as well as we can. - -The global variable |best_bet| will be set to the active node for the best -way to break the paragraph, and a few other variables are used to -help determine what is best. - -@<Glob...@>= -static pointer @!best_bet; /*use this passive node and its predecessors*/ -static int @!fewest_demerits; /*the demerits associated with |best_bet|*/ -static halfword @!best_line; /*line number following the last line of the new paragraph*/ -static int @!actual_looseness; /*the difference between |line_number(best_bet)| - and the optimum |best_line|*/ -static int @!line_diff; /*the difference between the current line number and - the optimum |best_line|*/ - -@ @<Try the final line break at the end of the paragraph...@>= -{@+try_break(eject_penalty, hyphenated); -if (link(active)!=last_active) - {@+@<Find an active node with fewest demerits@>; - if (looseness==0) goto done; - @<Find the best active node for the desired looseness@>; - if ((actual_looseness==looseness)||final_pass) goto done; - } -} - -@ @<Find an active node...@>= -r=link(active);fewest_demerits=awful_bad; -@/do@+{if (type(r)!=delta_node) if (total_demerits(r) < fewest_demerits) - {@+fewest_demerits=total_demerits(r);best_bet=r; - } -r=link(r); -}@+ while (!(r==last_active)); -best_line=line_number(best_bet) - -@ The adjustment for a desired looseness is a slightly more complicated -version of the loop just considered. Note that if a paragraph is broken -into segments by displayed equations, each segment will be subject to the -looseness calculation, independently of the other segments. - -@<Find the best active node...@>= -{@+r=link(active);actual_looseness=0; -@/do@+{if (type(r)!=delta_node) - {@+line_diff=line_number(r)-best_line; - if (((line_diff < actual_looseness)&&(looseness <= line_diff))||@| - ((line_diff > actual_looseness)&&(looseness >= line_diff))) - {@+best_bet=r;actual_looseness=line_diff; - fewest_demerits=total_demerits(r); - } - else if ((line_diff==actual_looseness)&&@| - (total_demerits(r) < fewest_demerits)) - {@+best_bet=r;fewest_demerits=total_demerits(r); - } - } -r=link(r); -}@+ while (!(r==last_active)); -best_line=line_number(best_bet); -} - -@ Once the best sequence of breakpoints has been found (hurray), we call on the -procedure |post_line_break| to finish the remainder of the work. -(By introducing this subprocedure, we are able to keep |line_break| -from getting extremely long.) - -@<Break the paragraph at the chosen...@>= -post_line_break(final_widow_penalty) - -@ The total number of lines that will be set by |post_line_break| -is |best_line-prev_graf-1|. The last breakpoint is specified by -|break_node(best_bet)|, and this passive node points to the other breakpoints -via the |prev_break| links. The finishing-up phase starts by linking the -relevant passive nodes in forward order, changing |prev_break| to -|next_break|. (The |next_break| fields actually reside in the same memory -space as the |prev_break| fields did, but we give them a new name because -of their new significance.) Then the lines are justified, one by one. - -@d next_break prev_break /*new name for |prev_break| after links are reversed*/ - -@<Declare subprocedures for |line_break|@>= -static void post_line_break(int @!final_widow_penalty) -{@+ -pointer q, @!r, @!s; /*temporary registers for list manipulation*/ -bool @!disc_break; /*was the current break at a discretionary node?*/ -bool @!post_disc_break; /*and did it have a nonempty post-break part?*/ -scaled @!cur_width; /*width of line number |cur_line|*/ -scaled @!cur_indent; /*left margin of line number |cur_line|*/ -quarterword @!t; /*used for replacement counts in discretionary nodes*/ -int @!pen; /*use when calculating penalties between lines*/ -halfword @!cur_line; /*the current line number being justified*/ -@<Reverse the links of the relevant passive nodes, setting |cur_p| to the first breakpoint@>; -cur_line=prev_graf+1; -@/do@+{@<Justify the line ending at breakpoint |cur_p|, and append it to the current -vertical list, together with associated penalties and other insertions@>; -incr(cur_line);cur_p=next_break(cur_p); -if (cur_p!=null) if (!post_disc_break) - @<Prune unwanted nodes at the beginning of the next line@>; -}@+ while (!(cur_p==null)); -if ((cur_line!=best_line)||(link(temp_head)!=null)) - confusion("line breaking"); -@:this can't happen line breaking}{\quad line breaking@> -prev_graf=best_line-1; -} - -@ The job of reversing links in a list is conveniently regarded as the job -of taking items off one stack and putting them on another. In this case we -take them off a stack pointed to by |q| and having |prev_break| fields; -we put them on a stack pointed to by |cur_p| and having |next_break| fields. -Node |r| is the passive node being moved from stack to stack. - -@<Reverse the links of the relevant passive nodes...@>= -q=break_node(best_bet);cur_p=null; -@/do@+{r=q;q=prev_break(q);next_break(r)=cur_p;cur_p=r; -}@+ while (!(q==null)) - -@ Glue and penalty and kern and math nodes are deleted at the beginning of -a line, except in the anomalous case that the node to be deleted is actually -one of the chosen breakpoints. Otherwise -the pruning done here is designed to match -the lookahead computation in |try_break|, where the |break_width| values -are computed for non-discretionary breakpoints. - -@<Prune unwanted nodes at the beginning of the next line@>= -{@+r=temp_head; -loop@+{@+q=link(r); - if (q==cur_break(cur_p)) goto done1; - /*|cur_break(cur_p)| is the next breakpoint*/ - /*now |q| cannot be |null|*/ - if (is_char_node(q)) goto done1; - if (non_discardable(q)) goto done1; - if (type(q)==kern_node) if (subtype(q)!=explicit) goto done1; - r=q; /*now |type(q)==glue_node|, |kern_node|, |math_node|, or |penalty_node|*/ - } -done1: if (r!=temp_head) - {@+link(r)=null;flush_node_list(link(temp_head)); - link(temp_head)=q; - } -} - -@ The current line to be justified appears in a horizontal list starting -at |link(temp_head)| and ending at |cur_break(cur_p)|. If |cur_break(cur_p)| is -a glue node, we reset the glue to equal the |right_skip| glue; otherwise -we append the |right_skip| glue at the right. If |cur_break(cur_p)| is a -discretionary node, we modify the list so that the discretionary break -is compulsory, and we set |disc_break| to |true|. We also append -the |left_skip| glue at the left of the line, unless it is zero. - -@<Justify the line ending at breakpoint |cur_p|, and append it...@>= -@<Modify the end of the line to reflect the nature of the break and to include \.{\\rightskip}; -also set the proper value of |disc_break|@>; -@<Put the \(l)\.{\\leftskip} glue at the left and detach this line@>; -@<Call the packaging subroutine, setting |just_box| to the justified box@>; -@<Append the new box to the current vertical list, followed by the list of special -nodes taken out of the box by the packager@>; -@<Append a penalty node, if a nonzero penalty is appropriate@>@; - -@ At the end of the following code, |q| will point to the final node on the -list about to be justified. - -@<Modify the end of the line...@>= -q=cur_break(cur_p);disc_break=false;post_disc_break=false; -if (q!=null) /*|q| cannot be a |char_node|*/ - if (type(q)==glue_node) - {@+delete_glue_ref(glue_ptr(q)); - glue_ptr(q)=right_skip; - subtype(q)=right_skip_code+1;add_glue_ref(right_skip); - goto done; - } - else{@+if (type(q)==disc_node) - @<Change discretionary to compulsory and set |disc_break:=true|@>@; - else if ((type(q)==math_node)||(type(q)==kern_node)) width(q)=0; - } -else{@+q=temp_head; - while (link(q)!=null) q=link(q); - } -@<Put the \(r)\.{\\rightskip} glue after node |q|@>; -done: - -@ @<Change discretionary to compulsory...@>= -{@+t=replace_count(q); -@<Destroy the |t| nodes following |q|, and make |r| point to the following node@>; -if (post_break(q)!=null) @<Transplant the post-break list@>; -if (pre_break(q)!=null) @<Transplant the pre-break list@>; -link(q)=r;disc_break=true; -} - -@ @<Destroy the |t| nodes following |q|...@>= -if (t==0) r=link(q); -else{@+r=q; - while (t > 1) - {@+r=link(r);decr(t); - } - s=link(r); - r=link(s);link(s)=null; - flush_node_list(link(q));set_replace_count(q,0); - } - -@ We move the post-break list from inside node |q| to the main list by -re\-attaching it just before the present node |r|, then resetting |r|. - -@<Transplant the post-break list@>= -{@+s=post_break(q); -while (link(s)!=null) s=link(s); -link(s)=r;r=post_break(q);post_break(q)=null;post_disc_break=true; -} - -@ We move the pre-break list from inside node |q| to the main list by -re\-attaching it just after the present node |q|, then resetting |q|. - -@<Transplant the pre-break list@>= -{@+s=pre_break(q);link(q)=s; -while (link(s)!=null) s=link(s); -pre_break(q)=null;q=s; -} - -@ @<Put the \(r)\.{\\rightskip} glue after node |q|@>= -r=new_param_glue(right_skip_code);link(r)=link(q);link(q)=r;q=r - -@ The following code begins with |q| at the end of the list to be -justified. It ends with |q| at the beginning of that list, and with -|link(temp_head)| pointing to the remainder of the paragraph, if any. - -@<Put the \(l)\.{\\leftskip} glue at the left...@>= -r=link(q);link(q)=null;q=link(temp_head);link(temp_head)=r; -if (left_skip!=zero_glue) - {@+r=new_param_glue(left_skip_code); - link(r)=q;q=r; - } - -@ @<Append the new box to the current vertical list...@>= -append_to_vlist(just_box); -if (adjust_head!=adjust_tail) - {@+link(tail)=link(adjust_head);tail=adjust_tail; - } -adjust_tail=null - -@ Now |q| points to the hlist that represents the current line of the -paragraph. We need to compute the appropriate line width, pack the -line into a box of this size, and shift the box by the appropriate -amount of indentation. - -@<Call the packaging subroutine...@>= -if (cur_line > last_special_line) - {@+cur_width=second_width;cur_indent=second_indent; - } -else if (par_shape_ptr==null) - {@+cur_width=first_width;cur_indent=first_indent; - } -else{@+cur_width=mem[par_shape_ptr+2*cur_line].sc; - cur_indent=mem[par_shape_ptr+2*cur_line-1].sc; - } -adjust_tail=adjust_head;just_box=hpack(q, cur_width, 0, 0, exactly); -shift_amount(just_box)=cur_indent - -@ Penalties between the lines of a paragraph come from club and widow lines, -from the |inter_line_penalty| parameter, and from lines that end at -discretionary breaks. Breaking between lines of a two-line paragraph gets -both club-line and widow-line penalties. The local variable |pen| will -be set to the sum of all relevant penalties for the current line, except -that the final line is never penalized. - -@<Append a penalty node, if a nonzero penalty is appropriate@>= -if (cur_line+1!=best_line) - {@+pen=inter_line_penalty; - if (cur_line==prev_graf+1) pen=pen+club_penalty; - if (cur_line+2==best_line) pen=pen+final_widow_penalty; - if (disc_break) pen=pen+broken_penalty; - if (pen!=0) - {@+r=new_penalty(pen); - link(tail)=r;tail=r; - } - } - -@* Pre-hyphenation. -When the line-breaking routine is unable to find a feasible sequence of -breakpoints, it makes a second pass over the paragraph, attempting to -hyphenate the hyphenatable words. The goal of hyphenation is to insert -discretionary material into the paragraph so that there are more -potential places to break. - -The general rules for hyphenation are somewhat complex and technical, -because we want to be able to hyphenate words that are preceded or -followed by punctuation marks, and because we want the rules to work -for languages other than English. We also must contend with the fact -that hyphens might radically alter the ligature and kerning structure -of a word. - -A sequence of characters will be considered for hyphenation only if it -belongs to a ``potentially hyphenatable part'' of the current paragraph. -This is a sequence of nodes $p_0p_1\ldots p_m$ where $p_0$ is a glue node, -$p_1\ldots p_{m-1}$ are either character or ligature or whatsit or -implicit kern nodes, and $p_m$ is a glue or penalty or insertion or adjust -or mark or whatsit or explicit kern node. (Therefore hyphenation is -disabled by boxes, math formulas, and discretionary nodes already inserted -by the user.) The ligature nodes among $p_1\ldots p_{m-1}$ are effectively -expanded into the original non-ligature characters; the kern nodes and -whatsits are ignored. Each character |c| is now classified as either a -nonletter (if |lc_code(c)==0|), a lowercase letter (if -|lc_code(c)==c|), or an uppercase letter (otherwise); an uppercase letter -is treated as if it were |lc_code(c)| for purposes of hyphenation. The -characters generated by $p_1\ldots p_{m-1}$ may begin with nonletters; let -$c_1$ be the first letter that is not in the middle of a ligature. Whatsit -nodes preceding $c_1$ are ignored; a whatsit found after $c_1$ will be the -terminating node $p_m$. All characters that do not have the same font as -$c_1$ will be treated as nonletters. The |hyphen_char| for that font -must be between 0 and 255, otherwise hyphenation will not be attempted. -\TeX\ looks ahead for as many consecutive letters $c_1\ldots c_n$ as -possible; however, |n| must be less than 64, so a character that would -otherwise be $c_{64}$ is effectively not a letter. Furthermore $c_n$ must -not be in the middle of a ligature. In this way we obtain a string of -letters $c_1\ldots c_n$ that are generated by nodes $p_a\ldots p_b$, where -|1 <= a <= b+1 <= m|. If |n >= l_hyf+r_hyf|, this string qualifies for hyphenation; -however, |uc_hyph| must be positive, if $c_1$ is uppercase. - -The hyphenation process takes place in three stages. First, the candidate -sequence $c_1\ldots c_n$ is found; then potential positions for hyphens -are determined by referring to hyphenation tables; and finally, the nodes -$p_a\ldots p_b$ are replaced by a new sequence of nodes that includes the -discretionary breaks found. - -Fortunately, we do not have to do all this calculation very often, because -of the way it has been taken out of \TeX's inner loop. For example, when -the second edition of the author's 700-page book {\sl Seminumerical -Algorithms} was typeset by \TeX, only about 1.2 hyphenations needed to be -@^Knuth, Donald Ervin@> -tried per paragraph, since the line breaking algorithm needed to use two -passes on only about 5 per cent of the paragraphs. - -@<Initialize for hyphenating...@>= -{ -#ifdef @!INIT -if (trie_not_ready) init_trie(); -#endif -@;@/ -cur_lang=init_cur_lang;l_hyf=init_l_hyf;r_hyf=init_r_hyf; -} - -@ The letters $c_1\ldots c_n$ that are candidates for hyphenation are placed -into an array called |hc|; the number |n| is placed into |hn|; pointers to -nodes $p_{a-1}$ and~$p_b$ in the description above are placed into variables -|ha| and |hb|; and the font number is placed into |hf|. - -@<Glob...@>= -static int16_t @!hc[66]; /*word to be hyphenated*/ -static int @!hn; /*the number of positions occupied in |hc|; - not always a |small_number|*/ -static pointer @!ha, @!hb; /*nodes |ha dotdot hb| should be replaced by the hyphenated result*/ -static internal_font_number @!hf; /*font number of the letters in |hc|*/ -static int16_t @!hu[64]; /*like |hc|, before conversion to lowercase*/ -static int @!hyf_char; /*hyphen character of the relevant font*/ -ASCII_code @!cur_lang, @!init_cur_lang; /*current hyphenation table of interest*/ -int @!l_hyf, @!r_hyf, @!init_l_hyf, @!init_r_hyf; /*limits on fragment sizes*/ -static halfword @!hyf_bchar; /*boundary character after $c_n$*/ - -@ Hyphenation routines need a few more local variables. - -@<Local variables for line...@>= -small_number @!j; /*an index into |hc| or |hu|*/ -int @!c; /*character being considered for hyphenation*/ - -@ When the following code is activated, the |line_break| procedure is in its -second pass, and |cur_p| points to a glue node. - -@p -void hyphenate_word(void)@t\2\2@>@/ -{ pointer @!q, @!s, @!prev_s;@t\1@> /*miscellaneous nodes of temporary interest*/ - small_number @!j; /*an index into |hc| or |hu|*/ - uint8_t @!c; /*character being considered for hyphenation*/ - - prev_s=cur_p;s=link(prev_s); -if (s!=null) - {@+@<Skip to node |ha|, or |goto done1| if no hyphenation should be attempted@>; - if (l_hyf+r_hyf > 63) goto done1; - @<Skip to node |hb|, putting letters into |hu| and |hc|@>; - @<Check that the nodes following |hb| permit hyphenation and that at least |l_hyf+r_hyf| -letters have been found, otherwise |goto done1|@>; - hyphenate(); - } -done1: ;} - -@ @<Declare subprocedures for |line_break|@>= -@t\4@>@<Declare the function called |reconstitute|@>@; -static void hyphenate(void) -{@+ -@<Local variables for hyphenation@>@; -@<Find hyphen locations for the word in |hc|, or |return|@>; -@<If no hyphens were found, |return|@>; -@<Replace nodes |ha..hb| by a sequence of nodes that includes the discretionary hyphens@>; -} - -@ The first thing we need to do is find the node |ha| just before the -first letter. - -@<Skip to node |ha|, or |goto done1|...@>= -loop@+{@+if (is_char_node(s)) - {@+c=qo(character(s));hf=font(s); - } - else if (type(s)==ligature_node) - if (lig_ptr(s)==null) goto resume; - else{@+q=lig_ptr(s);c=qo(character(q));hf=font(q); - } - else if ((type(s)==kern_node)&&(subtype(s)==normal)) goto resume; - else if (type(s)==whatsit_node) - {@+@<Advance \(p)past a whatsit node in the \(p)pre-hyphenation loop@>; - goto resume; - } - else goto done1; - if (lc_code(c)!=0) - if ((lc_code(c)==c)||(uc_hyph > 0)) goto done2; - else goto done1; -resume: prev_s=s;s=link(prev_s); - } -done2: hyf_char=hyphen_char[hf]; -if (hyf_char < 0) goto done1; -if (hyf_char > 255) goto done1; -ha=prev_s - -@ The word to be hyphenated is now moved to the |hu| and |hc| arrays. - -@<Skip to node |hb|, putting letters...@>= -hn=0; -loop@+{@+if (is_char_node(s)) - {@+if (font(s)!=hf) goto done3; - hyf_bchar=character(s);c=qo(hyf_bchar); - if (lc_code(c)==0) goto done3; - if (hn==63) goto done3; - hb=s;incr(hn);hu[hn]=c;hc[hn]=lc_code(c);hyf_bchar=non_char; - } - else if (type(s)==ligature_node) - @<Move the characters of a ligature node to |hu| and |hc|; but |goto done3| if -they are not all letters@>@; - else if ((type(s)==kern_node)&&(subtype(s)==normal)) - {@+hb=s; - hyf_bchar=font_bchar[hf]; - } - else goto done3; - s=link(s); - } -done3: - -@ We let |j| be the index of the character being stored when a ligature node -is being expanded, since we do not want to advance |hn| until we are sure -that the entire ligature consists of letters. Note that it is possible -to get to |done3| with |hn==0| and |hb| not set to any value. - -@<Move the characters of a ligature node to |hu| and |hc|...@>= -{@+if (font(lig_char(s))!=hf) goto done3; -j=hn;q=lig_ptr(s);@+if (q > null) hyf_bchar=character(q); -while (q > null) - {@+c=qo(character(q)); - if (lc_code(c)==0) goto done3; - if (j==63) goto done3; - incr(j);hu[j]=c;hc[j]=lc_code(c);@/ - q=link(q); - } -hb=s;hn=j; -if (odd(subtype(s))) hyf_bchar=font_bchar[hf];@+else hyf_bchar=non_char; -} - -@ @<Check that the nodes following |hb| permit hyphenation...@>= -if (hn < l_hyf+r_hyf) goto done1; /*|l_hyf| and |r_hyf| are | >= 1|*/ -loop@+{@+if (!(is_char_node(s))) - switch (type(s)) { - case ligature_node: do_nothing;@+break; - case kern_node: if (subtype(s)!=normal) goto done4;@+break; - case whatsit_node: case glue_node: case penalty_node: case ins_node: case adjust_node: case mark_node: - goto done4; - default:goto done1; - } - s=link(s); - } -done4: - -@* Post-hyphenation. -If a hyphen may be inserted between |hc[j]| and |hc[j+1]|, the hyphenation -procedure will set |hyf[j]| to some small odd number. But before we look -at \TeX's hyphenation procedure, which is independent of the rest of the -line-breaking algorithm, let us consider what we will do with the hyphens -it finds, since it is better to work on this part of the program before -forgetting what |ha| and |hb|, etc., are all about. - -@<Glob...@>= -static int8_t @!hyf[65]; /*odd values indicate discretionary hyphens*/ -static pointer @!init_list; /*list of punctuation characters preceding the word*/ -static bool @!init_lig; /*does |init_list| represent a ligature?*/ -static bool @!init_lft; /*if so, did the ligature involve a left boundary?*/ - -@ @<Local variables for hyphenation@>= -int @!i, @!j, @!l; /*indices into |hc| or |hu|*/ -pointer @!q, @!r, @!s; /*temporary registers for list manipulation*/ -halfword @!bchar; /*boundary character of hyphenated word, or |non_char|*/ - -@ \TeX\ will never insert a hyphen that has fewer than -\.{\\lefthyphenmin} letters before it or fewer than -\.{\\righthyphenmin} after it; hence, a short word has -comparatively little chance of being hyphenated. If no hyphens have -been found, we can save time by not having to make any changes to the -paragraph. - -@<If no hyphens were found, |return|@>= -for (j=l_hyf; j<=hn-r_hyf; j++) if (odd(hyf[j])) goto found1; -return; -found1: - -@ If hyphens are in fact going to be inserted, \TeX\ first deletes the -subsequence of nodes between |ha| and~|hb|. An attempt is made to -preserve the effect that implicit boundary characters and punctuation marks -had on ligatures inside the hyphenated word, by storing a left boundary or -preceding character in |hu[0]| and by storing a possible right boundary -in |bchar|. We set |j=0| if |hu[0]| is to be part of the reconstruction; -otherwise |j=1|. -The variable |s| will point to the tail of the current hlist, and -|q| will point to the node following |hb|, so that -things can be hooked up after we reconstitute the hyphenated word. - -@<Replace nodes |ha..hb| by a sequence of nodes...@>= -q=link(hb);link(hb)=null;r=link(ha);link(ha)=null;bchar=hyf_bchar; -if (is_char_node(ha)) - if (font(ha)!=hf) goto found2; - else{@+init_list=ha;init_lig=false;hu[0]=qo(character(ha)); - } -else if (type(ha)==ligature_node) - if (font(lig_char(ha))!=hf) goto found2; - else{@+init_list=lig_ptr(ha);init_lig=true;init_lft=(subtype(ha) > 1); - hu[0]=qo(character(lig_char(ha))); - if (init_list==null) if (init_lft) - {@+hu[0]=256;init_lig=false; - } /*in this case a ligature will be reconstructed from scratch*/ - free_node(ha, small_node_size); - } -else{@+ /*no punctuation found; look for left boundary*/ - if (!is_char_node(r)) if (type(r)==ligature_node) - if (subtype(r) > 1) goto found2; - j=1;s=ha;init_list=null;goto common_ending; - } -s=cur_p; /*we have |cur_p!=ha| because |type(cur_p)==glue_node|*/ -while (link(s)!=ha) s=link(s); -j=0;goto common_ending; -found2: s=ha;j=0;hu[0]=256;init_lig=false;init_list=null; -common_ending: flush_node_list(r); -@<Reconstitute nodes for the hyphenated word, inserting discretionary hyphens@>; -flush_list(init_list) - -@ We must now face the fact that the battle is not over, even though the -{\def\!{\kern-1pt}% -hyphens have been found: The process of reconstituting a word can be nontrivial -because ligatures might change when a hyphen is present. {\sl The \TeX book\/} -discusses the difficulties of the word ``difficult'', and -the discretionary material surrounding a -hyphen can be considerably more complex than that. Suppose -\.{abcdef} is a word in a font for which the only ligatures are \.{b\!c}, -\.{c\!d}, \.{d\!e}, and \.{e\!f}. If this word permits hyphenation -between \.b and \.c, the two patterns with and without hyphenation are -$\.a\,\.b\,\.-\,\.{c\!d}\,\.{e\!f}$ and $\.a\,\.{b\!c}\,\.{d\!e}\,\.f$. -Thus the insertion of a hyphen might cause effects to ripple arbitrarily -far into the rest of the word. A further complication arises if additional -hyphens appear together with such rippling, e.g., if the word in the -example just given could also be hyphenated between \.c and \.d; \TeX\ -avoids this by simply ignoring the additional hyphens in such weird cases.} - -Still further complications arise in the presence of ligatures that do not -delete the original characters. When punctuation precedes the word being -hyphenated, \TeX's method is not perfect under all possible scenarios, -because punctuation marks and letters can propagate information back and forth. -For example, suppose the original pre-hyphenation pair -\.{*a} changes to \.{*y} via a \.{\@@=:} ligature, which changes to \.{xy} -via a \.{=:\@@} ligature; if $p_{a-1}=\.x$ and $p_a=\.y$, the reconstitution -procedure isn't smart enough to obtain \.{xy} again. In such cases the -font designer should include a ligature that goes from \.{xa} to \.{xy}. - -@ The processing is facilitated by a subroutine called |reconstitute|. Given -a string of characters $x_j\ldots x_n$, there is a smallest index $m\ge j$ -such that the ``translation'' of $x_j\ldots x_n$ by ligatures and kerning -has the form $y_1\ldots y_t$ followed by the translation of $x_{m+1}\ldots x_n$, -where $y_1\ldots y_t$ is some nonempty sequence of character, ligature, and -kern nodes. We call $x_j\ldots x_m$ a ``cut prefix'' of $x_j\ldots x_n$. -For example, if $x_1x_2x_3=\.{fly}$, and if the font contains `fl' as a -ligature and a kern between `fl' and `y', then $m=2$, $t=2$, and $y_1$ will -be a ligature node for `fl' followed by an appropriate kern node~$y_2$. -In the most common case, $x_j$~forms no ligature with $x_{j+1}$ and we -simply have $m=j$, $y_1=x_j$. If $m<n$ we can repeat the procedure on -$x_{m+1}\ldots x_n$ until the entire translation has been found. - -The |reconstitute| function returns the integer $m$ and puts the nodes -$y_1\ldots y_t$ into a linked list starting at |link(hold_head)|, -getting the input $x_j\ldots x_n$ from the |hu| array. If $x_j=256$, -we consider $x_j$ to be an implicit left boundary character; in this -case |j| must be strictly less than~|n|. There is a -parameter |bchar|, which is either 256 or an implicit right boundary character -assumed to be present just following~$x_n$. (The value |hu[n+1]| is never -explicitly examined, but the algorithm imagines that |bchar| is there.) - -If there exists an index |k| in the range $j\le k\le m$ such that |hyf[k]| -is odd and such that the result of |reconstitute| would have been different -if $x_{k+1}$ had been |hchar|, then |reconstitute| sets |hyphen_passed| -to the smallest such~|k|. Otherwise it sets |hyphen_passed| to zero. - -A special convention is used in the case |j==0|: Then we assume that the -translation of |hu[0]| appears in a special list of charnodes starting at -|init_list|; moreover, if |init_lig| is |true|, then |hu[0]| will be -a ligature character, involving a left boundary if |init_lft| is |true|. -This facility is provided for cases when a hyphenated -word is preceded by punctuation (like single or double quotes) that might -affect the translation of the beginning of the word. - -@<Glob...@>= -static small_number @!hyphen_passed; /*first hyphen in a ligature, if any*/ - -@ @<Declare the function called |reconstitute|@>= -static - small_number reconstitute(small_number @!j, small_number @!n, halfword @!bchar, halfword @!hchar) -{@+ -pointer @!p; /*temporary register for list manipulation*/ -pointer @!t; /*a node being appended to*/ -four_quarters @!q; /*character information or a lig/kern instruction*/ -halfword @!cur_rh; /*hyphen character for ligature testing*/ -halfword @!test_char; /*hyphen or other character for ligature testing*/ -scaled @!w; /*amount of kerning*/ -font_index @!k; /*position of current lig/kern instruction*/ -hyphen_passed=0;t=hold_head;w=0;link(hold_head)=null; - /*at this point |ligature_present==lft_hit==rt_hit==false|*/ -@<Set up data structures with the cursor following position |j|@>; -resume: @<If there's a ligature or kern at the cursor position, update the data structures, -possibly advancing~|j|; continue until the cursor moves@>; -@<Append a ligature and/or kern to the translation; |goto continue| if the stack of -inserted ligatures is nonempty@>; -return j; -} - -@ The reconstitution procedure shares many of the global data structures -by which \TeX\ has processed the words before they were hyphenated. -There is an implied ``cursor'' between characters |cur_l| and |cur_r|; -these characters will be tested for possible ligature activity. If -|ligature_present| then |cur_l| is a ligature character formed from the -original characters following |cur_q| in the current translation list. -There is a ``ligature stack'' between the cursor and character |j+1|, -consisting of pseudo-ligature nodes linked together by their |link| fields. -This stack is normally empty unless a ligature command has created a new -character that will need to be processed later. A pseudo-ligature is -a special node having a |character| field that represents a potential -ligature and a |lig_ptr| field that points to a |char_node| or is |null|. -We have -$$|cur_r|=\cases{|character(lig_stack)|,&if |lig_stack > null|;\cr - \hbox{|qi(hu[j+1])|},&if |lig_stack==null| and |j < n|;\cr - bchar,&if |lig_stack==null| and |j==n|.\cr}$$ - -@<Glob...@>= -static halfword @!cur_l, @!cur_r; /*characters before and after the cursor*/ -static pointer @!cur_q; /*where a ligature should be detached*/ -static pointer @!lig_stack; /*unfinished business to the right of the cursor*/ -static bool @!ligature_present; /*should a ligature node be made for |cur_l|?*/ -static bool @!lft_hit, @!rt_hit; /*did we hit a ligature with a boundary character?*/ - -@ @d append_charnode_to_t(A) {@+link(t)=get_avail();t=link(t); - font(t)=hf;character(t)=A; - } -@d set_cur_r {@+if (j < n) cur_r=qi(hu[j+1]);@+else cur_r=bchar; - if (odd(hyf[j])) cur_rh=hchar;@+else cur_rh=non_char; - } - -@<Set up data structures with the cursor following position |j|@>= -cur_l=qi(hu[j]);cur_q=t; -if (j==0) - {@+ligature_present=init_lig;p=init_list; - if (ligature_present) lft_hit=init_lft; - while (p > null) - {@+append_charnode_to_t(character(p));p=link(p); - } - } -else if (cur_l < non_char) append_charnode_to_t(cur_l); -lig_stack=null;set_cur_r - -@ We may want to look at the lig/kern program twice, once for a hyphen -and once for a normal letter. (The hyphen might appear after the letter -in the program, so we'd better not try to look for both at once.) - -@<If there's a ligature or kern at the cursor position, update...@>= -if (cur_l==non_char) - {@+k=bchar_label[hf]; - if (k==non_address) goto done;@+else q=font_info[k].qqqq; - } -else{@+q=char_info(hf, cur_l); - if (char_tag(q)!=lig_tag) goto done; - k=lig_kern_start(hf, q);q=font_info[k].qqqq; - if (skip_byte(q) > stop_flag) - {@+k=lig_kern_restart(hf, q);q=font_info[k].qqqq; - } - } /*now |k| is the starting address of the lig/kern program*/ -if (cur_rh < non_char) test_char=cur_rh;@+else test_char=cur_r; -loop@+{@+if (next_char(q)==test_char) if (skip_byte(q) <= stop_flag) - if (cur_rh < non_char) - {@+hyphen_passed=j;hchar=non_char;cur_rh=non_char; - goto resume; - } - else{@+if (hchar < non_char) if (odd(hyf[j])) - {@+hyphen_passed=j;hchar=non_char; - } - if (op_byte(q) < kern_flag) - @<Carry out a ligature replacement, updating the cursor structure and possibly -advancing~|j|; |goto continue| if the cursor doesn't advance, otherwise |goto done|@>; - w=char_kern(hf, q);goto done; /*this kern will be inserted below*/ - } - if (skip_byte(q) >= stop_flag) - if (cur_rh==non_char) goto done; - else{@+cur_rh=non_char;goto resume; - } - k=k+qo(skip_byte(q))+1;q=font_info[k].qqqq; - } -done: - -@ @d wrap_lig(A) if (ligature_present) - {@+p=new_ligature(hf, cur_l, link(cur_q)); - if (lft_hit) - {@+subtype(p)=2;lft_hit=false; - } - if (A) if (lig_stack==null) - {@+incr(subtype(p));rt_hit=false; - } - link(cur_q)=p;t=p;ligature_present=false; - } -@d pop_lig_stack {@+if (lig_ptr(lig_stack) > null) - {@+link(t)=lig_ptr(lig_stack); /*this is a charnode for |hu[j+1]|*/ - t=link(t);incr(j); - } - p=lig_stack;lig_stack=link(p);free_node(p, small_node_size); - if (lig_stack==null) set_cur_r@;@+else cur_r=character(lig_stack); - } /*if |lig_stack| isn't |null| we have |cur_rh==non_char|*/ - -@<Append a ligature and/or kern to the translation...@>= -wrap_lig(rt_hit); -if (w!=0) - {@+link(t)=new_kern(w);t=link(t);w=0; - } -if (lig_stack > null) - {@+cur_q=t;cur_l=character(lig_stack);ligature_present=true; - pop_lig_stack;goto resume; - } - -@ @<Carry out a ligature replacement, updating the cursor structure...@>= -{@+if (cur_l==non_char) lft_hit=true; -if (j==n) if (lig_stack==null) rt_hit=true; -check_interrupt; /*allow a way out in case there's an infinite ligature loop*/ -switch (op_byte(q)) { -case qi(1): case qi(5): {@+cur_l=rem_byte(q); /*\.{=:\@@}, \.{=:\@@>}*/ - ligature_present=true; - } @+break; -case qi(2): case qi(6): {@+cur_r=rem_byte(q); /*\.{\@@=:}, \.{\@@=:>}*/ - if (lig_stack > null) character(lig_stack)=cur_r; - else{@+lig_stack=new_lig_item(cur_r); - if (j==n) bchar=non_char; - else{@+p=get_avail();lig_ptr(lig_stack)=p; - character(p)=qi(hu[j+1]);font(p)=hf; - } - } - } @+break; -case qi(3): {@+cur_r=rem_byte(q); /*\.{\@@=:\@@}*/ - p=lig_stack;lig_stack=new_lig_item(cur_r);link(lig_stack)=p; - } @+break; -case qi(7): case qi(11): {@+wrap_lig(false); /*\.{\@@=:\@@>}, \.{\@@=:\@@>>}*/ - cur_q=t;cur_l=rem_byte(q);ligature_present=true; - } @+break; -default:{@+cur_l=rem_byte(q);ligature_present=true; /*\.{=:}*/ - if (lig_stack > null) pop_lig_stack@; - else if (j==n) goto done; - else{@+append_charnode_to_t(cur_r);incr(j);set_cur_r; - } - } -} -if (op_byte(q) > qi(4)) if (op_byte(q)!=qi(7)) goto done; -goto resume; -} - -@ Okay, we're ready to insert the potential hyphenations that were found. -When the following program is executed, we want to append the word -|hu[1 dotdot hn]| after node |ha|, and node |q| should be appended to the result. -During this process, the variable |i| will be a temporary -index into |hu|; the variable |j| will be an index to our current position -in |hu|; the variable |l| will be the counterpart of |j|, in a discretionary -branch; the variable |r| will point to new nodes being created; and -we need a few new local variables: - -@<Local variables for hyph...@>= -pointer @!major_tail, @!minor_tail; /*the end of lists in the main and - discretionary branches being reconstructed*/ -ASCII_code @!c; /*character temporarily replaced by a hyphen*/ -int @!c_loc; /*where that character came from*/ -int @!r_count; /*replacement count for discretionary*/ -pointer @!hyf_node; /*the hyphen, if it exists*/ - -@ When the following code is performed, |hyf[0]| and |hyf[hn]| will be zero. - -@<Reconstitute nodes for the hyphenated word...@>= -@/do@+{l=j;j=reconstitute(j, hn, bchar, qi(hyf_char))+1; -if (hyphen_passed==0) - {@+link(s)=link(hold_head); - while (link(s) > null) s=link(s); - if (odd(hyf[j-1])) - {@+l=j;hyphen_passed=j-1;link(hold_head)=null; - } - } -if (hyphen_passed > 0) - @<Create and append a discretionary node as an alternative to the unhyphenated word, -and continue to develop both branches until they become equivalent@>; -}@+ while (!(j > hn)); -link(s)=q - -@ In this repeat loop we will insert another discretionary if |hyf[j-1]| is -odd, when both branches of the previous discretionary end at position |j-1|. -Strictly speaking, we aren't justified in doing this, because we don't know -that a hyphen after |j-1| is truly independent of those branches. But in almost -all applications we would rather not lose a potentially valuable hyphenation -point. (Consider the word `difficult', where the letter `c' is in position |j|.) - -@d advance_major_tail {@+major_tail=link(major_tail);incr(r_count); - } - -@<Create and append a discretionary node as an alternative...@>= -@/do@+{r=get_node(small_node_size); -link(r)=link(hold_head);type(r)=disc_node; -major_tail=r;r_count=0; -while (link(major_tail) > null) advance_major_tail; -i=hyphen_passed;hyf[i]=0; -@<Put the \(c)characters |hu[l..i]| and a hyphen into |pre_break(r)|@>; -@<Put the \(c)characters |hu[i+1..]| into |post_break(r)|, appending to this list -and to |major_tail| until synchronization has been achieved@>; -@<Move pointer |s| to the end of the current list, and set |replace_count(r)| appropriately@>; -hyphen_passed=j-1;link(hold_head)=null; -}@+ while (!(!odd(hyf[j-1]))) - -@ The new hyphen might combine with the previous character via ligature -or kern. At this point we have |l-1 <= i < j| and |i < hn|. - -@<Put the \(c)characters |hu[l..i]| and a hyphen into |pre_break(r)|@>= -minor_tail=null;pre_break(r)=null;hyf_node=new_character(hf, hyf_char); -if (hyf_node!=null) - {@+incr(i);c=hu[i];hu[i]=hyf_char;free_avail(hyf_node); - } -while (l <= i) - {@+l=reconstitute(l, i, font_bchar[hf], non_char)+1; - if (link(hold_head) > null) - {@+if (minor_tail==null) pre_break(r)=link(hold_head); - else link(minor_tail)=link(hold_head); - minor_tail=link(hold_head); - while (link(minor_tail) > null) minor_tail=link(minor_tail); - } - } -if (hyf_node!=null) - {@+hu[i]=c; /*restore the character in the hyphen position*/ - l=i;decr(i); - } - -@ The synchronization algorithm begins with |l==i+1 <= j|. - -@<Put the \(c)characters |hu[i+1..]| into |post_break(r)|...@>= -minor_tail=null;post_break(r)=null;c_loc=0; -if (bchar_label[hf]!=non_address) /*put left boundary at beginning of new line*/ - {@+decr(l);c=hu[l];c_loc=l;hu[l]=256; - } -while (l < j) - {@+@/do@+{l=reconstitute(l, hn, bchar, non_char)+1; - if (c_loc > 0) - {@+hu[c_loc]=c;c_loc=0; - } - if (link(hold_head) > null) - {@+if (minor_tail==null) post_break(r)=link(hold_head); - else link(minor_tail)=link(hold_head); - minor_tail=link(hold_head); - while (link(minor_tail) > null) minor_tail=link(minor_tail); - } - }@+ while (!(l >= j)); - while (l > j) - @<Append characters of |hu[j..]| to |major_tail|, advancing~|j|@>; - } - -@ @<Append characters of |hu[j..]|...@>= -{@+j=reconstitute(j, hn, bchar, non_char)+1; -link(major_tail)=link(hold_head); -while (link(major_tail) > null) advance_major_tail; -} - -@ Ligature insertion can cause a word to grow exponentially in size. Therefore -we must test the size of |r_count| here, even though the hyphenated text -was at most 63 characters long. - -@<Move pointer |s| to the end of the current list...@>= -if (r_count > 127) /*we have to forget the discretionary hyphen*/ - {@+link(s)=link(r);link(r)=null;flush_node_list(r); - } -else{@+link(s)=r;set_replace_count(r,r_count);set_auto_disc(r); - } -s=major_tail - -@* Hyphenation. -When a word |hc[1 dotdot hn]| has been set up to contain a candidate for hyphenation, -\TeX\ first looks to see if it is in the user's exception dictionary. If not, -hyphens are inserted based on patterns that appear within the given word, -using an algorithm due to Frank~M. Liang. -@^Liang, Franklin Mark@> - -Let's consider Liang's method first, since it is much more interesting than the -exception-lookup routine. The algorithm begins by setting |hyf[j]| to zero -for all |j|, and invalid characters are inserted into |hc[0]| -and |hc[hn+1]| to serve as delimiters. Then a reasonably fast method is -used to see which of a given set of patterns occurs in the word -|hc[0 dotdot(hn+1)]|. Each pattern $p_1\ldots p_k$ of length |k| has an associated -sequence of |k+1| numbers $n_0\ldots n_k$; and if the pattern occurs in -|hc[(j+1)dotdot(j+k)]|, \TeX\ will set |hyf[j+i]=@tmax@>(hyf[j+i],@t$n\_i$@>)| for -|0 <= i <= k|. After this has been done for each pattern that occurs, a -discretionary hyphen will be inserted between |hc[j]| and |hc[j+1]| when -|hyf[j]| is odd, as we have already seen. - -The set of patterns $p_1\ldots p_k$ and associated numbers $n_0\ldots n_k$ -depends, of course, on the language whose words are being hyphenated, and -on the degree of hyphenation that is desired. A method for finding -appropriate |p|'s and |n|'s, from a given dictionary of words and acceptable -hyphenations, is discussed in Liang's Ph.D. thesis (Stanford University, -1983); \TeX\ simply starts with the patterns and works from there. - -@ The patterns are stored in a compact table that is also efficient for -retrieval, using a variant of ``trie memory'' [cf.\ {\sl The Art of -Computer Programming \bf3} (1973), 481--505]. We can find each pattern -$p_1\ldots p_k$ by letting $z_0$ be one greater than the relevant language -index and then, for |1 <= i <= k|, -setting |@t$z\_i$@>=trie_link@t$(z\_{i-1})+p\_i$@>|; the pattern will be -identified by the number $z_k$. Since all the pattern information is -packed together into a single |trie_link| array, it is necessary to -prevent confusion between the data from inequivalent patterns, so another -table is provided such that |trie_char@t$(z\_i)=p\_i$@>| for all |i|. There -is also a table |trie_op|$(z_k)$ to identify the numbers $n_0\ldots n_k$ -associated with $p_1\ldots p_k$. - -Comparatively few different number sequences $n_0\ldots n_k$ actually occur, -since most of the |n|'s are generally zero. Therefore the number sequences -are encoded in such a way that |trie_op|$(z_k)$ is only one byte long. -If |trie_op(@t$z\_k$@>)!=min_quarterword|, when $p_1\ldots p_k$ has matched -the letters in |hc[(l-k+1)dotdot l@,]| of language |t|, -we perform all of the required operations -for this pattern by carrying out the following little program: Set -|v=trie_op(@t$z\_k$@>)|. Then set |v=v+op_start[t]|, -|hyf[l-hyf_distance[v]]=@tmax@>(hyf[l-hyf_distance[v]], hyf_num[v])|, -and |v=hyf_next[v]|; repeat, if necessary, until |v==min_quarterword|. - -@<Types...@>= -typedef int32_t trie_pointer; /*an index into |trie|*/ - -@ @d trie_link(A) trie[A].rh /*``downward'' link in a trie*/ -@d trie_char(A) trie[A].b1 /*character matched at this trie location*/ -@d trie_op(A) trie[A].b0 /*program for hyphenation at this trie location*/ - -@<Glob...@>= -static two_halves @!trie[trie_size+1]; /*|trie_link|, |trie_char|, |trie_op|*/ -static small_number @!hyf_distance0[trie_op_size], *const @!hyf_distance = @!hyf_distance0-1; /*position |k-j| of $n_j$*/ -static small_number @!hyf_num0[trie_op_size], *const @!hyf_num = @!hyf_num0-1; /*value of $n_j$*/ -static quarterword @!hyf_next0[trie_op_size], *const @!hyf_next = @!hyf_next0-1; /*continuation code*/ -static uint16_t @!op_start[256]; /*offset for current language*/ - -@ @<Local variables for hyph...@>= -trie_pointer @!z; /*an index into |trie|*/ -int @!v; /*an index into |hyf_distance|, etc.*/ - -@ Assuming that these auxiliary tables have been set up properly, the -hyphenation algorithm is quite short. In the following code we set |hc[hn+2]| -to the impossible value 256, in order to guarantee that |hc[hn+3]| will -never be fetched. - -@<Find hyphen locations for the word in |hc|...@>= -for (j=0; j<=hn; j++) hyf[j]=0; -@<Look for the word |hc[1..hn]| in the exception table, and |goto found| (with |hyf| -containing the hyphens) if an entry is found@>; -if (trie_char(cur_lang+1)!=qi(cur_lang)) return; /*no patterns for |cur_lang|*/ -hc[0]=0;hc[hn+1]=0;hc[hn+2]=256; /*insert delimiters*/ -for (j=0; j<=hn-r_hyf+1; j++) - {@+z=trie_link(cur_lang+1)+hc[j];l=j; - while (hc[l]==qo(trie_char(z))) - {@+if (trie_op(z)!=min_quarterword) - @<Store \(m)maximum values in the |hyf| table@>; - incr(l);z=trie_link(z)+hc[l]; - } - } -found: for (j=0; j<=l_hyf-1; j++) hyf[j]=0; -for (j=0; j<=r_hyf-1; j++) hyf[hn-j]=0 - -@ @<Store \(m)maximum values in the |hyf| table@>= -{@+v=trie_op(z); -@/do@+{v=v+op_start[cur_lang];i=l-hyf_distance[v]; -if (hyf_num[v] > hyf[i]) hyf[i]=hyf_num[v]; -v=hyf_next[v]; -}@+ while (!(v==min_quarterword)); -} - -@ The exception table that is built by \TeX's \.{\\hyphenation} primitive is -organized as an ordered hash table [cf.\ Amble and Knuth, {\sl The Computer -@^Amble, Ole@> @^Knuth, Donald Ervin@> -Journal\/ \bf17} (1974), 135--142] using linear probing. If $\alpha$ and -$\beta$ are words, we will say that $\alpha<\beta$ if $\vert\alpha\vert< -\vert\beta\vert$ or if $\vert\alpha\vert=\vert\beta\vert$ and -$\alpha$ is lexicographically smaller than $\beta$. (The notation $\vert -\alpha\vert$ stands for the length of $\alpha$.) The idea of ordered hashing -is to arrange the table so that a given word $\alpha$ can be sought by computing -a hash address $h=h(\alpha)$ and then looking in table positions |h|, |h-1|, -\dots, until encountering the first word $\le\alpha$. If this word is -different from $\alpha$, we can conclude that $\alpha$ is not in the table. - -The words in the table point to lists in |mem| that specify hyphen positions -in their |info| fields. The list for $c_1\ldots c_n$ contains the number |k| if -the word $c_1\ldots c_n$ has a discretionary hyphen between $c_k$ and -$c_{k+1}$. - -@<Types...@>= -typedef int16_t hyph_pointer; /*an index into the ordered hash table*/ - -@ @<Glob...@>= -static str_number @!hyph_word[hyph_size+1]; /*exception words*/ -static pointer @!hyph_list[hyph_size+1]; /*lists of hyphen positions*/ -static hyph_pointer @!hyph_count; /*the number of words in the exception dictionary*/ - -@ @<Local variables for init...@>= -int @!z; /*runs through the exception dictionary*/ - -@ @<Set init...@>= -for (z=0; z<=hyph_size; z++) - {@+hyph_word[z]=0;hyph_list[z]=null; - } -hyph_count=0; - -@ The algorithm for exception lookup is quite simple, as soon as we have -a few more local variables to work with. - -@<Local variables for hyph...@>= -hyph_pointer @!h; /*an index into |hyph_word| and |hyph_list|*/ -str_number @!k; /*an index into |str_start|*/ -pool_pointer @!u; /*an index into |str_pool|*/ - -@ First we compute the hash code |h|, then we search until we either -find the word or we don't. Words from different languages are kept -separate by appending the language code to the string. - -@<Look for the word |hc[1...@>= -h=hc[1];incr(hn);hc[hn]=cur_lang; -for (j=2; j<=hn; j++) h=(h+h+hc[j])%hyph_size; -loop@+{@+@<If the string |hyph_word[h]| is less than \(hc)|hc[1..hn]|, |goto not_found|; -but if the two strings are equal, set |hyf| to the hyphen positions and |goto found|@>; - if (h > 0) decr(h);@+else h=hyph_size; - } -not_found: decr(hn) - -@ @<If the string |hyph_word[h]| is less than \(hc)...@>= -k=hyph_word[h];if (k==0) goto not_found; -if (length(k) < hn) goto not_found; -if (length(k)==hn) - {@+j=1;u=str_start[k]; - @/do@+{if (so(str_pool[u]) < hc[j]) goto not_found; - if (so(str_pool[u]) > hc[j]) goto done; - incr(j);incr(u); - }@+ while (!(j > hn)); - @<Insert hyphens as specified in |hyph_list[h]|@>; - decr(hn);goto found; - } -done: - -@ @<Insert hyphens as specified...@>= -s=hyph_list[h]; -while (s!=null) - {@+hyf[info(s)]=1;s=link(s); - } - -@ @<Search |hyph_list| for pointers to |p|@>= -for (q=0; q<=hyph_size; q++) - {@+if (hyph_list[q]==p) - {@+print_nl("HYPH(");print_int(q);print_char(')'); - } - } - -@ We have now completed the hyphenation routine, so the |line_break| procedure -is finished at last. Since the hyphenation exception table is fresh in our -minds, it's a good time to deal with the routine that adds new entries to it. - -When \TeX\ has scanned `\.{\\hyphenation}', it calls on a procedure named -|new_hyph_exceptions| to do the right thing. - -@d set_cur_lang if (language <= 0) cur_lang=0; - else if (language > 255) cur_lang=0; - else cur_lang=language - -@p static void new_hyph_exceptions(void) /*enters new exceptions*/ -{@+ -int n; /*length of current word; not always a |small_number|*/ -int @!j; /*an index into |hc|*/ -hyph_pointer @!h; /*an index into |hyph_word| and |hyph_list|*/ -str_number @!k; /*an index into |str_start|*/ -pointer @!p; /*head of a list of hyphen positions*/ -pointer @!q; /*used when creating a new node for list |p|*/ -str_number @!s, @!t; /*strings being compared or stored*/ -pool_pointer @!u, @!v; /*indices into |str_pool|*/ -scan_left_brace(); /*a left brace must follow \.{\\hyphenation}*/ -set_cur_lang; -@<Enter as many hyphenation exceptions as are listed, until coming to a right brace; -then |return|@>; -} - -@ @<Enter as many...@>= -n=0;p=null; -loop@+{@+get_x_token(); - reswitch: switch (cur_cmd) { - case letter: case other_char: case char_given: @<Append a new letter or hyphen@>@;@+break; - case char_num: {@+scan_char_num();cur_chr=cur_val;cur_cmd=char_given; - goto reswitch; - } - case spacer: case right_brace: {@+if (n > 1) @<Enter a hyphenation exception@>; - if (cur_cmd==right_brace) return; - n=0;p=null; - } @+break; - default:@<Give improper \.{\\hyphenation} error@>@; - } - } - -@ @<Give improper \.{\\hyph...@>= -{@+print_err("Improper ");print_esc("hyphenation"); -@.Improper \\hyphenation...@> - print(" will be flushed"); -help2("Hyphenation exceptions must contain only letters",@/ - "and hyphens. But continue; I'll forgive and forget."); -error(); -} - -@ @<Append a new letter or hyphen@>= -if (cur_chr=='-') @<Append the value |n| to list |p|@>@; -else{@+if (lc_code(cur_chr)==0) - {@+print_err("Not a letter"); -@.Not a letter@> - help2("Letters in \\hyphenation words must have \\lccode>0.",@/ - "Proceed; I'll ignore the character I just read."); - error(); - } - else if (n < 63) - {@+incr(n);hc[n]=lc_code(cur_chr); - } - } - -@ @<Append the value |n| to list |p|@>= -{@+if (n < 63) - {@+q=get_avail();link(q)=p;info(q)=n;p=q; - } -} - -@ @<Enter a hyphenation exception@>= -{@+incr(n);hc[n]=cur_lang;str_room(n);h=0; -for (j=1; j<=n; j++) - {@+h=(h+h+hc[j])%hyph_size; - append_char(hc[j]); - } -s=make_string(); -@<Insert the \(p)pair |(s,p)| into the exception table@>; -} - -@ @<Insert the \(p)pair |(s,p)|...@>= -if (hyph_count==hyph_size) overflow("exception dictionary", hyph_size); -@:TeX capacity exceeded exception dictionary}{\quad exception dictionary@> -incr(hyph_count); -while (hyph_word[h]!=0) - {@+@<If the string |hyph_word[h]| is less than \(or)or equal to |s|, interchange -|(hyph_word[h],hyph_list[h])| with |(s,p)|@>; - if (h > 0) decr(h);@+else h=hyph_size; - } -hyph_word[h]=s;hyph_list[h]=p - -@ @<If the string |hyph_word[h]| is less than \(or)...@>= -k=hyph_word[h]; -if (length(k) < length(s)) goto found; -if (length(k) > length(s)) goto not_found; -u=str_start[k];v=str_start[s]; -@/do@+{if (str_pool[u] < str_pool[v]) goto found; -if (str_pool[u] > str_pool[v]) goto not_found; -incr(u);incr(v); -}@+ while (!(u==str_start[k+1])); -found: q=hyph_list[h];hyph_list[h]=p;p=q;@/ -t=hyph_word[h];hyph_word[h]=s;s=t; -not_found: - -@* Initializing the hyphenation tables. -The trie for \TeX's hyphenation algorithm is built from a sequence of -patterns following a \.{\\patterns} specification. Such a specification -is allowed only in \.{INITEX}, since the extra memory for auxiliary tables -and for the initialization program itself would only clutter up the -production version of \TeX\ with a lot of deadwood. - -The first step is to build a trie that is linked, instead of packed -into sequential storage, so that insertions are readily made. -After all patterns have been processed, \.{INITEX} -compresses the linked trie by identifying common subtries. Finally the -trie is packed into the efficient sequential form that the hyphenation -algorithm actually uses. - -@<Declare subprocedures for |line_break|@>= -#ifdef @!INIT -@<Declare procedures for preprocessing hyphenation patterns@>@; -#endif - -@ Before we discuss trie building in detail, let's consider the simpler -problem of creating the |hyf_distance|, |hyf_num|, and |hyf_next| arrays. - -Suppose, for example, that \TeX\ reads the pattern `\.{ab2cde1}'. This is -a pattern of length 5, with $n_0\ldots n_5=0\,0\,2\,0\,0\,1$ in the -notation above. We want the corresponding |trie_op| code |v| to have -|hyf_distance[v]==3|, |hyf_num[v]==2|, and |hyf_next[v]==@t$v^\prime$@>|, -where the auxiliary |trie_op| code $v^\prime$ has -|hyf_distance[@t$v^\prime$@>]==0|, |hyf_num[@t$v^\prime$@>]==1|, and -|hyf_next[@t$v^\prime$@>]==min_quarterword|. - -\TeX\ computes an appropriate value |v| with the |new_trie_op| subroutine -below, by setting -$$\hbox{|@t$v^\prime$@>=new_trie_op(0, 1, min_quarterword)|,\qquad -|v=new_trie_op(3, 2,@t$v^\prime$@>)|.}$$ -This subroutine looks up its three -parameters in a special hash table, assigning a new value only if these -three have not appeared before for the current language. - -The hash table is called |trie_op_hash|, and the number of entries it contains -is |trie_op_ptr|. - -@<Glob...@>= -#ifdef @!INIT -static uint16_t @!trie_op_hash0[trie_op_size+trie_op_size+1], *const @!trie_op_hash = @!trie_op_hash0+trie_op_size; - /*trie op codes for quadruples*/ -static quarterword @!trie_used[256]; - /*largest opcode used so far for this language*/ -static ASCII_code @!trie_op_lang0[trie_op_size], *const @!trie_op_lang = @!trie_op_lang0-1; - /*language part of a hashed quadruple*/ -static quarterword @!trie_op_val0[trie_op_size], *const @!trie_op_val = @!trie_op_val0-1; - /*opcode corresponding to a hashed quadruple*/ -static int @!trie_op_ptr; /*number of stored ops so far*/ -#endif - -@ It's tempting to remove the |overflow| stops in the following procedure; -|new_trie_op| could return |min_quarterword| (thereby simply ignoring -part of a hyphenation pattern) instead of aborting the job. However, that would -lead to different hyphenation results on different installations of \TeX\ -using the same patterns. The |overflow| stops are necessary for portability -of patterns. - -@<Declare procedures for preprocessing hyph...@>= -static quarterword new_trie_op(small_number @!d, small_number @!n, quarterword @!v) -{@+ -int h; /*trial hash location*/ -quarterword @!u; /*trial op code*/ -int @!l; /*pointer to stored data*/ -h=abs(n+313*d+361*v+1009*cur_lang)%(trie_op_size+trie_op_size) - -trie_op_size; -loop@+{@+l=trie_op_hash[h]; - if (l==0) /*empty position found for a new op*/ - {@+if (trie_op_ptr==trie_op_size) - overflow("pattern memory ops", trie_op_size); - u=trie_used[cur_lang]; - if (u==max_quarterword) - overflow("pattern memory ops per language", - max_quarterword-min_quarterword); - incr(trie_op_ptr);incr(u);trie_used[cur_lang]=u; - hyf_distance[trie_op_ptr]=d; - hyf_num[trie_op_ptr]=n;hyf_next[trie_op_ptr]=v; - trie_op_lang[trie_op_ptr]=cur_lang;trie_op_hash[h]=trie_op_ptr; - trie_op_val[trie_op_ptr]=u;return u; - } - if ((hyf_distance[l]==d)&&(hyf_num[l]==n)&&(hyf_next[l]==v) - &&(trie_op_lang[l]==cur_lang)) - {@+return trie_op_val[l]; - } - if (h > -trie_op_size) decr(h);@+else h=trie_op_size; - } -} - -@ After |new_trie_op| has compressed the necessary opcode information, -plenty of information is available to unscramble the data into the -final form needed by our hyphenation algorithm. - -@<Sort \(t)the hyphenation op tables into proper order@>= -op_start[0]=-min_quarterword; -for (j=1; j<=255; j++) op_start[j]=op_start[j-1]+qo(trie_used[j-1]); -for (j=1; j<=trie_op_ptr; j++) - trie_op_hash[j]=op_start[trie_op_lang[j]]+trie_op_val[j]; /*destination*/ -for (j=1; j<=trie_op_ptr; j++) while (trie_op_hash[j] > j) - {@+k=trie_op_hash[j];@/ - t=hyf_distance[k];hyf_distance[k]=hyf_distance[j];hyf_distance[j]=t;@/ - t=hyf_num[k];hyf_num[k]=hyf_num[j];hyf_num[j]=t;@/ - t=hyf_next[k];hyf_next[k]=hyf_next[j];hyf_next[j]=t;@/ - trie_op_hash[j]=trie_op_hash[k];trie_op_hash[k]=k; - } - -@ Before we forget how to initialize the data structures that have been -mentioned so far, let's write down the code that gets them started. - -@<Initialize table entries...@>= -for (k=-trie_op_size; k<=trie_op_size; k++) trie_op_hash[k]=0; -for (k=0; k<=255; k++) trie_used[k]=min_quarterword; -trie_op_ptr=0; - -@ The linked trie that is used to preprocess hyphenation patterns appears -in several global arrays. Each node represents an instruction of the form -``if you see character |c|, then perform operation |o|, move to the -next character, and go to node |l|; otherwise go to node |r|.'' -The four quantities |c|, |o|, |l|, and |r| are stored in four arrays -|trie_c|, |trie_o|, |trie_l|, and |trie_r|. The root of the trie -is |trie_l[0]|, and the number of nodes is |trie_ptr|. Null trie -pointers are represented by zero. To initialize the trie, we simply -set |trie_l[0]| and |trie_ptr| to zero. We also set |trie_c[0]| to some -arbitrary value, since the algorithm may access it. - -The algorithms maintain the condition -$$\hbox{|trie_c[trie_r[z]] > trie_c[z]|\qquad -whenever |z!=0| and |trie_r[z]!=0|};$$ in other words, sibling nodes are -ordered by their |c| fields. - -@d trie_root trie_l[0] /*root of the linked trie*/ - -@<Glob...@>= -#ifdef @!INIT -static packed_ASCII_code @!trie_c[trie_size+1]; - /*characters to match*/ -@t\hskip10pt@>static quarterword @!trie_o[trie_size+1]; - /*operations to perform*/ -@t\hskip10pt@>static trie_pointer @!trie_l[trie_size+1]; - /*left subtrie links*/ -@t\hskip10pt@>static trie_pointer @!trie_r[trie_size+1]; - /*right subtrie links*/ -@t\hskip10pt@>static trie_pointer @!trie_ptr; /*the number of nodes in the trie*/ -@t\hskip10pt@>static trie_pointer @!trie_hash[trie_size+1]; - /*used to identify equivalent subtries*/ -#endif - -@ Let us suppose that a linked trie has already been constructed. -Experience shows that we can often reduce its size by recognizing common -subtries; therefore another hash table is introduced for this purpose, -somewhat similar to |trie_op_hash|. The new hash table will be -initialized to zero. - -The function |trie_node(p)| returns |p| if |p| is distinct from other nodes -that it has seen, otherwise it returns the number of the first equivalent -node that it has seen. - -Notice that we might make subtries equivalent even if they correspond to -patterns for different languages, in which the trie ops might mean quite -different things. That's perfectly all right. - -@<Declare procedures for preprocessing hyph...@>= -static trie_pointer trie_node(trie_pointer @!p) /*converts - to a canonical form*/ -{@+ -trie_pointer h; /*trial hash location*/ -trie_pointer @!q; /*trial trie node*/ -h=abs(trie_c[p]+1009*trie_o[p]+@| - 2718*trie_l[p]+3142*trie_r[p])%trie_size; -loop@+{@+q=trie_hash[h]; - if (q==0) - {@+trie_hash[h]=p;return p; - } - if ((trie_c[q]==trie_c[p])&&(trie_o[q]==trie_o[p])&&@| - (trie_l[q]==trie_l[p])&&(trie_r[q]==trie_r[p])) - {@+return q; - } - if (h > 0) decr(h);@+else h=trie_size; - } -} - -@ A neat recursive procedure is now able to compress a trie by -traversing it and applying |trie_node| to its nodes in ``bottom up'' -fashion. We will compress the entire trie by clearing |trie_hash| to -zero and then saying `|trie_root=compress_trie(trie_root)|'. -@^recursion@> - -@<Declare procedures for preprocessing hyph...@>= -static trie_pointer compress_trie(trie_pointer @!p) -{@+if (p==0) return 0; -else{@+trie_l[p]=compress_trie(trie_l[p]); - trie_r[p]=compress_trie(trie_r[p]); - return trie_node(p); - } -} - -@ The compressed trie will be packed into the |trie| array using a -``top-down first-fit'' procedure. This is a little tricky, so the reader -should pay close attention: The |trie_hash| array is cleared to zero -again and renamed |trie_ref| for this phase of the operation; later on, -|trie_ref[p]| will be nonzero only if the linked trie node |p| is the -smallest character -in a family and if the characters |c| of that family have been allocated to -locations |trie_ref[p]+c| in the |trie| array. Locations of |trie| that -are in use will have |trie_link==0|, while the unused holes in |trie| -will be doubly linked with |trie_link| pointing to the next larger vacant -location and |trie_back| pointing to the next smaller one. This double -linking will have been carried out only as far as |trie_max|, where -|trie_max| is the largest index of |trie| that will be needed. -To save time at the low end of the trie, we maintain array entries -|trie_min[c]| pointing to the smallest hole that is greater than~|c|. -Another array |trie_taken| tells whether or not a given location is -equal to |trie_ref[p]| for some |p|; this array is used to ensure that -distinct nodes in the compressed trie will have distinct |trie_ref| -entries. - -@d trie_ref trie_hash /*where linked trie families go into |trie|*/ -@d trie_back(A) trie[A].lh /*backward links in |trie| holes*/ - -@<Glob...@>= -#ifdef @!INIT -static bool @!trie_taken0[trie_size], *const @!trie_taken = @!trie_taken0-1; - /*does a family start here?*/ -@t\hskip10pt@>static trie_pointer @!trie_min[256]; - /*the first possible slot for each character*/ -@t\hskip10pt@>static trie_pointer @!trie_max; /*largest location used in |trie|*/ -@t\hskip10pt@>bool @!trie_not_ready; /*is the trie still in linked form?*/ -#endif - -@ Each time \.{\\patterns} appears, it contributes further patterns to -the future trie, which will be built only when hyphenation is attempted or -when a format file is dumped. The boolean variable |trie_not_ready| -will change to |false| when the trie is compressed; this will disable -further patterns. - -@<Initialize table entries...@>= -trie_not_ready=true;trie_root=0;trie_c[0]=si(0);trie_ptr=0; - -@ Here is how the trie-compression data structures are initialized. -If storage is tight, it would be possible to overlap |trie_op_hash|, -|trie_op_lang|, and |trie_op_val| with |trie|, |trie_hash|, and |trie_taken|, -because we finish with the former just before we need the latter. - -@<Get ready to compress the trie@>= -@<Sort \(t)the hyphenation...@>; -for (p=0; p<=trie_size; p++) trie_hash[p]=0; -trie_root=compress_trie(trie_root); /*identify equivalent subtries*/ -for (p=0; p<=trie_ptr; p++) trie_ref[p]=0; -for (p=0; p<=255; p++) trie_min[p]=p+1; -trie_link(0)=1;trie_max=0 - -@ The |first_fit| procedure finds the smallest hole |z| in |trie| such that -a trie family starting at a given node |p| will fit into vacant positions -starting at |z|. If |c==trie_c[p]|, this means that location |z-c| must -not already be taken by some other family, and that |z-c+@t$c^\prime$@>| -must be vacant for all characters $c^\prime$ in the family. The procedure -sets |trie_ref[p]| to |z-c| when the first fit has been found. - -@<Declare procedures for preprocessing hyph...@>= -static void first_fit(trie_pointer @!p) /*packs a family into |trie|*/ -{@+ -trie_pointer h; /*candidate for |trie_ref[p]|*/ -trie_pointer @!z; /*runs through holes*/ -trie_pointer @!q; /*runs through the family starting at |p|*/ -ASCII_code @!c; /*smallest character in the family*/ -trie_pointer @!l, @!r; /*left and right neighbors*/ -int @!ll; /*upper limit of |trie_min| updating*/ -c=so(trie_c[p]); -z=trie_min[c]; /*get the first conceivably good hole*/ -loop@+{@+h=z-c;@/ - @<Ensure that |trie_max>=h+256|@>; - if (trie_taken[h]) goto not_found; - @<If all characters of the family fit relative to |h|, then |goto found|,\30\ otherwise -|goto not_found|@>; - not_found: z=trie_link(z); /*move to the next hole*/ - } -found: @<Pack the family into |trie| relative to |h|@>; -} - -@ By making sure that |trie_max| is at least |h+256|, we can be sure that -|trie_max > z|, since |h==z-c|. It follows that location |trie_max| will -never be occupied in |trie|, and we will have |trie_max >= trie_link(z)|. - -@<Ensure that |trie_max>=h+256|@>= -if (trie_max < h+256) - {@+if (trie_size <= h+256) overflow("pattern memory", trie_size); -@:TeX capacity exceeded pattern memory}{\quad pattern memory@> - @/do@+{incr(trie_max);trie_taken[trie_max]=false; - trie_link(trie_max)=trie_max+1;trie_back(trie_max)=trie_max-1; - }@+ while (!(trie_max==h+256)); - } - -@ @<If all characters of the family fit relative to |h|...@>= -q=trie_r[p]; -while (q > 0) - {@+if (trie_link(h+so(trie_c[q]))==0) goto not_found; - q=trie_r[q]; - } -goto found - -@ @<Pack the family into |trie| relative to |h|@>= -trie_taken[h]=true;trie_ref[p]=h;q=p; -@/do@+{z=h+so(trie_c[q]);l=trie_back(z);r=trie_link(z); -trie_back(r)=l;trie_link(l)=r;trie_link(z)=0; -if (l < 256) - {@+if (z < 256) ll=z;@+else ll=256; - @/do@+{trie_min[l]=r;incr(l); - }@+ while (!(l==ll)); - } -q=trie_r[q]; -}@+ while (!(q==0)) - -@ To pack the entire linked trie, we use the following recursive procedure. -@^recursion@> - -@<Declare procedures for preprocessing hyph...@>= -static void trie_pack(trie_pointer @!p) /*pack subtries of a family*/ -{@+trie_pointer q; /*a local variable that need not be saved on recursive calls*/ -@/do@+{q=trie_l[p]; -if ((q > 0)&&(trie_ref[q]==0)) - {@+first_fit(q);trie_pack(q); - } -p=trie_r[p]; -}@+ while (!(p==0)); -} - -@ When the whole trie has been allocated into the sequential table, we -must go through it once again so that |trie| contains the correct -information. Null pointers in the linked trie will be represented by the -value~0, which properly implements an ``empty'' family. - -@<Move the data into |trie|@>= -h.rh=0;h.b0=min_quarterword;h.b1=min_quarterword; /*|trie_link=0|, - |trie_op=min_quarterword|, |trie_char=qi(0)|*/ -if (trie_root==0) /*no patterns were given*/ - {@+for (r=0; r<=256; r++) trie[r]=h; - trie_max=256; - } -else{@+trie_fix(trie_root); /*this fixes the non-holes in |trie|*/ - r=0; /*now we will zero out all the holes*/ - @/do@+{s=trie_link(r);trie[r]=h;r=s; - }@+ while (!(r > trie_max)); - } -trie_char(0)=qi('?'); /*make |trie_char(c)!=c| for all |c|*/ - -@ The fixing-up procedure is, of course, recursive. Since the linked trie -usually has overlapping subtries, the same data may be moved several -times; but that causes no harm, and at most as much work is done as it -took to build the uncompressed trie. -@^recursion@> - -@<Declare procedures for preprocessing hyph...@>= -static void trie_fix(trie_pointer @!p) /*moves |p| and its siblings into |trie|*/ -{@+trie_pointer q; /*a local variable that need not be saved on recursive calls*/ -ASCII_code @!c; /*another one that need not be saved*/ -trie_pointer @!z; /*|trie| reference; this local variable must be saved*/ -z=trie_ref[p]; -@/do@+{q=trie_l[p];c=so(trie_c[p]); -trie_link(z+c)=trie_ref[q];trie_char(z+c)=qi(c);trie_op(z+c)=trie_o[p]; -if (q > 0) trie_fix(q); -p=trie_r[p]; -}@+ while (!(p==0)); -} - -@ Now let's go back to the easier problem, of building the linked -trie. When \.{INITEX} has scanned the `\.{\\patterns}' control -sequence, it calls on |new_patterns| to do the right thing. - -@<Declare procedures for preprocessing hyph...@>= -static void new_patterns(void) /*initializes the hyphenation pattern data*/ -{@+ -int k, @!l; /*indices into |hc| and |hyf|; - not always in |small_number| range*/ -bool @!digit_sensed; /*should the next digit be treated as a letter?*/ -quarterword @!v; /*trie op code*/ -trie_pointer @!p, @!q; /*nodes of trie traversed during insertion*/ -bool @!first_child; /*is |p==trie_l[q]|?*/ -ASCII_code @!c; /*character being inserted*/ -if (trie_not_ready) - {@+set_cur_lang;scan_left_brace(); /*a left brace must follow \.{\\patterns}*/ - @<Enter all of the patterns into a linked trie, until coming to a right brace@>; - } -else{@+print_err("Too late for ");print_esc("patterns"); - help1("All patterns must be given before typesetting begins."); - error();link(garbage)=scan_toks(false, false);flush_list(def_ref); - } -} - -@ Novices are not supposed to be using \.{\\patterns}, so the error -messages are terse. (Note that all error messages appear in \TeX's string -pool, even if they are used only by \.{INITEX}.) - -@<Enter all of the patterns into a linked trie...@>= -k=0;hyf[0]=0;digit_sensed=false; -loop@+{@+get_x_token(); - switch (cur_cmd) { - case letter: case other_char: @<Append a new letter or a hyphen level@>@;@+break; - case spacer: case right_brace: {@+if (k > 0) - @<Insert a new pattern into the linked trie@>; - if (cur_cmd==right_brace) goto done; - k=0;hyf[0]=0;digit_sensed=false; - } @+break; - default:{@+print_err("Bad ");print_esc("patterns"); -@.Bad \\patterns@> - help1("(See Appendix H.)");error(); - } - } - } -done: - -@ @<Append a new letter or a hyphen level@>= -if (digit_sensed||(cur_chr < '0')||(cur_chr > '9')) - {@+if (cur_chr=='.') cur_chr=0; /*edge-of-word delimiter*/ - else{@+cur_chr=lc_code(cur_chr); - if (cur_chr==0) - {@+print_err("Nonletter"); -@.Nonletter@> - help1("(See Appendix H.)");error(); - } - } - if (k < 63) - {@+incr(k);hc[k]=cur_chr;hyf[k]=0;digit_sensed=false; - } - } -else if (k < 63) - {@+hyf[k]=cur_chr-'0';digit_sensed=true; - } - -@ When the following code comes into play, the pattern $p_1\ldots p_k$ -appears in |hc[1 dotdot k]|, and the corresponding sequence of numbers $n_0\ldots -n_k$ appears in |hyf[0 dotdot k]|. - -@<Insert a new pattern into the linked trie@>= -{@+@<Compute the trie op code, |v|, and set |l:=0|@>; -q=0;hc[0]=cur_lang; -while (l <= k) - {@+c=hc[l];incr(l);p=trie_l[q];first_child=true; - while ((p > 0)&&(c > so(trie_c[p]))) - {@+q=p;p=trie_r[q];first_child=false; - } - if ((p==0)||(c < so(trie_c[p]))) - @<Insert a new trie node between |q| and |p|, and make |p| point to it@>; - q=p; /*now node |q| represents $p_1\ldots p_{l-1}$*/ - } -if (trie_o[q]!=min_quarterword) - {@+print_err("Duplicate pattern"); -@.Duplicate pattern@> - help1("(See Appendix H.)");error(); - } -trie_o[q]=v; -} - -@ @<Insert a new trie node between |q| and |p|...@>= -{@+if (trie_ptr==trie_size) overflow("pattern memory", trie_size); -@:TeX capacity exceeded pattern memory}{\quad pattern memory@> -incr(trie_ptr);trie_r[trie_ptr]=p;p=trie_ptr;trie_l[p]=0; -if (first_child) trie_l[q]=p;@+else trie_r[q]=p; -trie_c[p]=si(c);trie_o[p]=min_quarterword; -} - -@ @<Compute the trie op code, |v|...@>= -if (hc[1]==0) hyf[0]=0; -if (hc[k]==0) hyf[k]=0; -l=k;v=min_quarterword; -loop@+{@+if (hyf[l]!=0) v=new_trie_op(k-l, hyf[l], v); - if (l > 0) decr(l);@+else goto done1; - } -done1: - -@ Finally we put everything together: Here is how the trie gets to its -final, efficient form. -The following packing routine is rigged so that the root of the linked -tree gets mapped into location 1 of |trie|, as required by the hyphenation -algorithm. This happens because the first call of |first_fit| will -``take'' location~1. - -@<Declare procedures for preprocessing hyphenation patterns@>= -void init_trie(void) -{@+int @!p; /*pointer for initialization*/ -int @!j, @!k, @!t; /*all-purpose registers for initialization*/ -int @!r, @!s; /*used to clean up the packed |trie|*/ -two_halves @!h; /*template used to zero out |trie|'s holes*/ -@<Get ready to compress the trie@>; -if (trie_root!=0) - {@+first_fit(trie_root);trie_pack(trie_root); - } -@<Move the data into |trie|@>; -trie_not_ready=false; -} - -@* Breaking vertical lists into pages. -The |vsplit| procedure, which implements \TeX's \.{\\vsplit} operation, -is considerably simpler than |line_break| because it doesn't have to -worry about hyphenation, and because its mission is to discover a single -break instead of an optimum sequence of breakpoints. But before we get -into the details of |vsplit|, we need to consider a few more basic things. - -@ A subroutine called |prune_page_top| takes a pointer to a vlist and -returns a pointer to a modified vlist in which all glue, kern, and penalty nodes -have been deleted before the first box or rule node. However, the first -box or rule is actually preceded by a newly created glue node designed so that -the topmost baseline will be at distance |split_top_skip| from the top, -whenever this is possible without backspacing. - -In this routine and those that follow, we make use of the fact that a -vertical list contains no character nodes, hence the |type| field exists -for each node in the list. -@^data structure assumptions@> - -@p static pointer prune_page_top(pointer @!p) /*adjust top after page break*/ -{@+pointer prev_p; /*lags one step behind |p|*/ -pointer @!q; /*temporary variable for list manipulation*/ -prev_p=temp_head;link(temp_head)=p; -while (p!=null) - switch (type(p)) { - case hlist_node: case vlist_node: case rule_node: @<Insert glue for |split_top_skip| -and set~|p:=null|@>@;@+break; - case whatsit_node: case mark_node: case ins_node: {@+prev_p=p;p=link(prev_p); - } @+break; - case glue_node: case kern_node: case penalty_node: {@+q=p;p=link(q);link(q)=null; - link(prev_p)=p;flush_node_list(q); - } @+break; - default:confusion("pruning"); -@:this can't happen pruning}{\quad pruning@> - } -return link(temp_head); -} - -@ @<Insert glue for |split_top_skip|...@>= -{@+q=new_skip_param(split_top_skip_code);link(prev_p)=q;link(q)=p; - /*now |temp_ptr==glue_ptr(q)|*/ -if (width(temp_ptr) > height(p)) width(temp_ptr)=width(temp_ptr)-height(p); -else width(temp_ptr)=0; -p=null; -} - -@ The next subroutine finds the best place to break a given vertical list -so as to obtain a box of height~|h|, with maximum depth~|d|. -A pointer to the beginning of the vertical list is given, -and a pointer to the optimum breakpoint is returned. The list is effectively -followed by a forced break, i.e., a penalty node with the |eject_penalty|; -if the best break occurs at this artificial node, the value |null| is returned. - -An array of six |scaled| distances is used to keep track of the height -from the beginning of the list to the current place, just as in |line_break|. -In fact, we use one of the same arrays, only changing its name to reflect -its new significance. - -@d active_height active_width /*new name for the six distance variables*/ -@d cur_height active_height[1] /*the natural height*/ -@d set_height_zero(A) active_height[A]=0 /*initialize the height to zero*/ -@# -@p static pointer vert_break(pointer @!p, scaled @!h, scaled @!d) - /*finds optimum page break*/ -{@+ -pointer prev_p; /*if |p| is a glue node, |type(prev_p)| determines - whether |p| is a legal breakpoint*/ -pointer @!q, @!r; /*glue specifications*/ -int @!pi; /*penalty value*/ -int @!b; /*badness at a trial breakpoint*/ -int @!least_cost; /*the smallest badness plus penalties found so far*/ -pointer @!best_place; /*the most recent break that leads to |least_cost|*/ -scaled @!prev_dp; /*depth of previous box in the list*/ -small_number @!t; /*|type| of the node following a kern*/ -prev_p=p; /*an initial glue node is not a legal breakpoint*/ -least_cost=awful_bad;do_all_six(set_height_zero);prev_dp=0; -loop@+{@+@<If node |p| is a legal breakpoint, check if this break is the best known, -and |goto done| if |p| is null or if the page-so-far is already too full to accept -more stuff@>; - prev_p=p;p=link(prev_p); - } -done: return best_place; -} - -@ A global variable |best_height_plus_depth| will be set to the natural size -of the box that corresponds to the optimum breakpoint found by |vert_break|. -(This value is used by the insertion-splitting algorithm of the page builder.) - -@<Glob...@>= -static scaled @!best_height_plus_depth; /*height of the best box, without stretching or - shrinking*/ - -@ A subtle point to be noted here is that the maximum depth~|d| might be -negative, so |cur_height| and |prev_dp| might need to be corrected even -after a glue or kern node. - -@<If node |p| is a legal breakpoint, check...@>= -if (p==null) pi=eject_penalty; -else@<Use node |p| to update the current height and depth measurements; if this node -is not a legal breakpoint, |goto not_found| or |update_heights|, otherwise set |pi| -to the associated penalty at the break@>; -@<Check if node |p| is a new champion breakpoint; then \(go)|goto done| if |p| is -a forced break or if the page-so-far is already too full@>; -if ((type(p) < glue_node)||(type(p) > kern_node)) goto not_found; -update_heights: @<Update the current height and depth measurements with respect to -a glue or kern node~|p|@>; -not_found: if (prev_dp > d) - {@+cur_height=cur_height+prev_dp-d; - prev_dp=d; - } - -@ @<Use node |p| to update the current height and depth measurements...@>= -switch (type(p)) { -case hlist_node: case vlist_node: case rule_node: {@+@t@>@;@/ - cur_height=cur_height+prev_dp+height(p);prev_dp=depth(p); - goto not_found; - } -case whatsit_node: @<Process whatsit |p| in |vert_break| loop, |goto not_found|@>; -case glue_node: if (precedes_break(prev_p)) pi=0; - else goto update_heights;@+break; -case kern_node: {@+if (link(p)==null) t=penalty_node; - else t=type(link(p)); - if (t==glue_node) pi=0;@+else goto update_heights; - } @+break; -case penalty_node: pi=penalty(p);@+break; -case mark_node: case ins_node: goto not_found; -default:confusion("vertbreak"); -@:this can't happen vertbreak}{\quad vertbreak@> -} - -@ @d deplorable 100000 /*more than |inf_bad|, but less than |awful_bad|*/ - -@<Check if node |p| is a new champion breakpoint; then \(go)...@>= -if (pi < inf_penalty) - {@+@<Compute the badness, |b|, using |awful_bad| if the box is too full@>; - if (b < awful_bad) - if (pi <= eject_penalty) b=pi; - else if (b < inf_bad) b=b+pi; - else b=deplorable; - if (b <= least_cost) - {@+best_place=p;least_cost=b; - best_height_plus_depth=cur_height+prev_dp; - } - if ((b==awful_bad)||(pi <= eject_penalty)) goto done; - } - -@ @<Compute the badness, |b|, using |awful_bad| if the box is too full@>= -if (cur_height < h) - if ((active_height[3]!=0)||(active_height[4]!=0)|| - (active_height[5]!=0)) b=0; - else b=badness(h-cur_height, active_height[2]); -else if (cur_height-h > active_height[6]) b=awful_bad; -else b=badness(cur_height-h, active_height[6]) - -@ Vertical lists that are subject to the |vert_break| procedure should not -contain infinite shrinkability, since that would permit any amount of -information to ``fit'' on one page. - -@<Update the current height and depth measurements with...@>= -if (type(p)==kern_node) q=p; -else{@+q=glue_ptr(p); - active_height[2+stretch_order(q)]=@| - active_height[2+stretch_order(q)]+stretch(q);@/ - active_height[6]=active_height[6]+shrink(q); - if ((shrink_order(q)!=normal)&&(shrink(q)!=0)) - {@+@t@>@;@/ - print_err("Infinite glue shrinkage found in box being split");@/ -@.Infinite glue shrinkage...@> - help4("The box you are \\vsplitting contains some infinitely",@/ - "shrinkable glue, e.g., `\\vss' or `\\vskip 0pt minus 1fil'.",@/ - "Such glue doesn't belong there; but you can safely proceed,",@/ - "since the offensive shrinkability has been made finite."); - error();r=new_spec(q);shrink_order(r)=normal;delete_glue_ref(q); - glue_ptr(p)=r;q=r; - } - } -cur_height=cur_height+prev_dp+width(q);prev_dp=0 - -@ Now we are ready to consider |vsplit| itself. Most of -its work is accomplished by the two subroutines that we have just considered. - -Given the number of a vlist box |n|, and given a desired page height |h|, -the |vsplit| function finds the best initial segment of the vlist and -returns a box for a page of height~|h|. The remainder of the vlist, if -any, replaces the original box, after removing glue and penalties and -adjusting for |split_top_skip|. Mark nodes in the split-off box are used to -set the values of |split_first_mark| and |split_bot_mark|; we use the -fact that |split_first_mark==null| if and only if |split_bot_mark==null|. - -The original box becomes ``void'' if and only if it has been entirely -extracted. The extracted box is ``void'' if and only if the original -box was void (or if it was, erroneously, an hlist box). - -@p static pointer vsplit(halfword @!n, scaled @!h) - /*extracts a page of height |h| from box |n|*/ -{@+ -pointer v; /*the box to be split*/ -pointer p; /*runs through the vlist*/ -pointer q; /*points to where the break occurs*/ -cur_val=n;fetch_box(v); -if (split_first_mark!=null) - {@+delete_token_ref(split_first_mark);split_first_mark=null; - delete_token_ref(split_bot_mark);split_bot_mark=null; - } -@<Dispense with trivial cases of void or bad boxes@>; -q=vert_break(list_ptr(v), h, split_max_depth); -@<Look at all the marks in nodes before the break, and set the final link to |null| -at the break@>; -q=prune_page_top(q);p=list_ptr(v);list_ptr(v)=null;flush_node_list(v); -if (q!=null) q=vpack(q, natural); -change_box(q); /*the |eq_level| of the box stays the same*/ -return vpackage(p, h, 0, 0, exactly, split_max_depth); -} - -@ @<Dispense with trivial cases of void or bad boxes@>= -if (v==null) - {@+return null; - } -if (type(v)!=vlist_node) - {@+print_err("");print_esc("vsplit");print(" needs a "); - print_esc("vbox"); -@:vsplit\_}{\.{\\vsplit needs a \\vbox}@> - help2("The box you are trying to split is an \\hbox.",@/ - "I can't split such a box, so I'll leave it alone."); - error();return null; - } - -@ It's possible that the box begins with a penalty node that is the -``best'' break, so we must be careful to handle this special case correctly. - -@<Look at all the marks...@>= -p=list_ptr(v); -if (p==q) list_ptr(v)=null; -else loop@+{@+if (type(p)==mark_node) - if (split_first_mark==null) - {@+split_first_mark=mark_ptr(p); - split_bot_mark=split_first_mark; - token_ref_count(split_first_mark)=@| - token_ref_count(split_first_mark)+2; - } - else{@+delete_token_ref(split_bot_mark); - split_bot_mark=mark_ptr(p); - add_token_ref(split_bot_mark); - } - if (link(p)==q) - {@+link(p)=null;goto done; - } - p=link(p); - } -done: - -@* The page builder. -When \TeX\ appends new material to its main vlist in vertical mode, it uses -a method something like |vsplit| to decide where a page ends, except that -the calculations are done ``on line'' as new items come in. -The main complication in this process is that insertions must be put -into their boxes and removed from the vlist, in a more-or-less optimum manner. - -We shall use the term ``current page'' for that part of the main vlist that -is being considered as a candidate for being broken off and sent to the -user's output routine. The current page starts at |link(page_head)|, and -it ends at |page_tail|. We have |page_head==page_tail| if this list is empty. -@^current page@> - -Utter chaos would reign if the user kept changing page specifications -while a page is being constructed, so the page builder keeps the pertinent -specifications frozen as soon as the page receives its first box or -insertion. The global variable |page_contents| is |empty| when the -current page contains only mark nodes and content-less whatsit nodes; it -is |inserts_only| if the page contains only insertion nodes in addition to -marks and whatsits. Glue nodes, kern nodes, and penalty nodes are -discarded until a box or rule node appears, at which time |page_contents| -changes to |box_there|. As soon as |page_contents| becomes non-|empty|, -the current |vsize| and |max_depth| are squirreled away into |page_goal| -and |page_max_depth|; the latter values will be used until the page has -been forwarded to the user's output routine. The \.{\\topskip} adjustment -is made when |page_contents| changes to |box_there|. - -Although |page_goal| starts out equal to |vsize|, it is decreased by the -scaled natural height-plus-depth of the insertions considered so far, and by -the \.{\\skip} corrections for those insertions. Therefore it represents -the size into which the non-inserted material should fit, assuming that -all insertions in the current page have been made. - -The global variables |best_page_break| and |least_page_cost| correspond -respectively to the local variables |best_place| and |least_cost| in the -|vert_break| routine that we have already studied; i.e., they record the -location and value of the best place currently known for breaking the -current page. The value of |page_goal| at the time of the best break is -stored in |best_size|. - -@d inserts_only 1 - /*|page_contents| when an insert node has been contributed, but no boxes*/ -@d box_there 2 /*|page_contents| when a box or rule has been contributed*/ - -@<Glob...@>= -static pointer @!page_tail; /*the final node on the current page*/ -int @!page_contents; /*what is on the current page so far?*/ -static scaled @!page_max_depth; /*maximum box depth on page being built*/ -static pointer @!best_page_break; /*break here to get the best page known so far*/ -static int @!least_page_cost; /*the score for this currently best page*/ -static scaled @!best_size; /*its |page_goal|*/ - -@ The page builder has another data structure to keep track of insertions. -This is a list of four-word nodes, starting and ending at |page_ins_head|. -That is, the first element of the list is node |r@t$\_1$@>==link(page_ins_head)|; -node $r_j$ is followed by |r@t$\_{j+1}$@>==link(r@t$\_j$@>)|; and if there are -|n| items we have |r@t$\_{n+1}$@>==page_ins_head|. The |subtype| field of -each node in this list refers to an insertion number; for example, `\.{\\insert -250}' would correspond to a node whose |subtype| is |qi(250)| -(the same as the |subtype| field of the relevant |ins_node|). These |subtype| -fields are in increasing order, and |subtype(page_ins_head)== -qi(255)|, so |page_ins_head| serves as a convenient sentinel -at the end of the list. A record is present for each insertion number that -appears in the current page. - -The |type| field in these nodes distinguishes two possibilities that -might occur as we look ahead before deciding on the optimum page break. -If |type(r)==inserting|, then |height(r)| contains the total of the -height-plus-depth dimensions of the box and all its inserts seen so far. -If |type(r)==split_up|, then no more insertions will be made into this box, -because at least one previous insertion was too big to fit on the current -page; |broken_ptr(r)| points to the node where that insertion will be -split, if \TeX\ decides to split it, |broken_ins(r)| points to the -insertion node that was tentatively split, and |height(r)| includes also the -natural height plus depth of the part that would be split off. - -In both cases, |last_ins_ptr(r)| points to the last |ins_node| -encountered for box |qo(subtype(r))| that would be at least partially -inserted on the next page; and |best_ins_ptr(r)| points to the last -such |ins_node| that should actually be inserted, to get the page with -minimum badness among all page breaks considered so far. We have -|best_ins_ptr(r)==null| if and only if no insertion for this box should -be made to produce this optimum page. - -The data structure definitions here use the fact that the |@!height| field -appears in the fourth word of a box node. -@^data structure assumptions@> - -@d page_ins_node_size 4 /*number of words for a page insertion node*/ -@d inserting 0 /*an insertion class that has not yet overflowed*/ -@d split_up 1 /*an overflowed insertion class*/ -@d broken_ptr(A) link(A+1) - /*an insertion for this class will break here if anywhere*/ -@d broken_ins(A) info(A+1) /*this insertion might break at |broken_ptr|*/ -@d last_ins_ptr(A) link(A+2) /*the most recent insertion for this |subtype|*/ -@d best_ins_ptr(A) info(A+2) /*the optimum most recent insertion*/ - -@<Initialize the special list heads...@>= -subtype(page_ins_head)=qi(255); -type(page_ins_head)=split_up;link(page_ins_head)=page_ins_head; - -@ An array |page_so_far| records the heights and depths of everything -on the current page. This array contains six |scaled| numbers, like the -similar arrays already considered in |line_break| and |vert_break|; and it -also contains |page_goal| and |page_depth|, since these values are -all accessible to the user via |set_page_dimen| commands. The -value of |page_so_far[1]| is also called |page_total|. The stretch -and shrink components of the \.{\\skip} corrections for each insertion are -included in |page_so_far|, but the natural space components of these -corrections are not, since they have been subtracted from |page_goal|. - -The variable |page_depth| records the depth of the current page; it has been -adjusted so that it is at most |page_max_depth|. The variable -|last_glue| points to the glue specification of the most recent node -contributed from the contribution list, if this was a glue node; otherwise -|last_glue==max_halfword|. (If the contribution list is nonempty, -however, the value of |last_glue| is not necessarily accurate.) -The variables |last_penalty|, |last_kern|, and |last_node_type| -are similar. And -finally, |insert_penalties| holds the sum of the penalties associated with -all split and floating insertions. - -@d page_goal page_so_far[0] /*desired height of information on page being built*/ -@d page_total page_so_far[1] /*height of the current page*/ -@d page_shrink page_so_far[6] /*shrinkability of the current page*/ -@d page_depth page_so_far[7] /*depth of the current page*/ - -@<Glob...@>= -scaled @!page_so_far[8]; /*height and glue of the current page*/ -static pointer @!last_glue; /*used to implement \.{\\lastskip}*/ -static int @!last_penalty; /*used to implement \.{\\lastpenalty}*/ -static scaled @!last_kern; /*used to implement \.{\\lastkern}*/ -static int @!last_node_type; /*used to implement \.{\\lastnodetype}*/ -static int @!insert_penalties; /*sum of the penalties for insertions - that were held over*/ - -@ @<Put each...@>= -primitive("pagegoal", set_page_dimen, 0); -@!@:page\_goal\_}{\.{\\pagegoal} primitive@> -primitive("pagetotal", set_page_dimen, 1); -@!@:page\_total\_}{\.{\\pagetotal} primitive@> -primitive("pagestretch", set_page_dimen, 2); -@!@:page\_stretch\_}{\.{\\pagestretch} primitive@> -primitive("pagefilstretch", set_page_dimen, 3); -@!@:page\_fil\_stretch\_}{\.{\\pagefilstretch} primitive@> -primitive("pagefillstretch", set_page_dimen, 4); -@!@:page\_fill\_stretch\_}{\.{\\pagefillstretch} primitive@> -primitive("pagefilllstretch", set_page_dimen, 5); -@!@:page\_filll\_stretch\_}{\.{\\pagefilllstretch} primitive@> -primitive("pageshrink", set_page_dimen, 6); -@!@:page\_shrink\_}{\.{\\pageshrink} primitive@> -primitive("pagedepth", set_page_dimen, 7); -@!@:page\_depth\_}{\.{\\pagedepth} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case set_page_dimen: switch (chr_code) { -case 0: print_esc("pagegoal");@+break; -case 1: print_esc("pagetotal");@+break; -case 2: print_esc("pagestretch");@+break; -case 3: print_esc("pagefilstretch");@+break; -case 4: print_esc("pagefillstretch");@+break; -case 5: print_esc("pagefilllstretch");@+break; -case 6: print_esc("pageshrink");@+break; -default:print_esc("pagedepth"); -} @+break; - -@ @d print_plus(A, B) if (page_so_far[A]!=0) - {@+print(" plus ");print_scaled(page_so_far[A]);print(B);@+} - -@p static void print_totals(void) -{@+print_scaled(page_total); -print_plus(2,""); -print_plus(3,"fil"); -print_plus(4,"fill"); -print_plus(5,"filll"); -if (page_shrink!=0) - {@+print(" minus ");print_scaled(page_shrink); - } -} - -@ @<Show the status of the current page@>= -if (page_head!=page_tail) - {@+print_nl("### current page:"); - if (output_active) print(" (held over for next output)"); -@.held over for next output@> - show_box(link(page_head)); - if (page_contents > empty) - {@+print_nl("total height ");print_totals(); -@:total\_height}{\.{total height}@> - print_nl(" goal height ");print_scaled(page_goal); -@.goal height@> - r=link(page_ins_head); - while (r!=page_ins_head) - {@+print_ln();print_esc("insert");t=qo(subtype(r)); - print_int(t);print(" adds "); - if (count(t)==1000) t=height(r); - else t=x_over_n(height(r), 1000)*count(t); - print_scaled(t); - if (type(r)==split_up) - {@+q=page_head;t=0; - @/do@+{q=link(q); - if ((type(q)==ins_node)&&(subtype(q)==subtype(r))) incr(t); - }@+ while (!(q==broken_ins(r))); - print(", #");print_int(t);print(" might split"); - } - r=link(r); - } - } - } - -@ Here is a procedure that is called when the |page_contents| is changing -from |empty| to |inserts_only| or |box_there|. - -@d set_page_so_far_zero(A) page_so_far[A]=0 - -@p void freeze_page_specs(small_number @!s) -{@+page_contents=s; -page_goal=vsize;page_max_depth=max_depth; -page_depth=0;do_all_six(set_page_so_far_zero); -least_page_cost=awful_bad; -#ifdef @!STAT -if (tracing_pages > 0) - {@+begin_diagnostic(); - print_nl("%% goal height=");print_scaled(page_goal); -@.goal height@> - print(", max depth=");print_scaled(page_max_depth); - end_diagnostic(false); - } @; -#endif -@;@/ -} - -@ Pages are built by appending nodes to the current list in \TeX's -vertical mode, which is at the outermost level of the semantic nest. This -vlist is split into two parts; the ``current page'' that we have been -talking so much about already, and the ``contribution list'' that receives -new nodes as they are created. The current page contains everything that -the page builder has accounted for in its data structures, as described -above, while the contribution list contains other things that have been -generated by other parts of \TeX\ but have not yet been -seen by the page builder. -The contribution list starts at |link(contrib_head)|, and it ends at the -current node in \TeX's vertical mode. - -When \TeX\ has appended new material in vertical mode, it calls the procedure -|build_page|, which tries to catch up by moving nodes from the contribution -list to the current page. This procedure will succeed in its goal of -emptying the contribution list, unless a page break is discovered, i.e., -unless the current page has grown to the point where the optimum next -page break has been determined. In the latter case, the nodes after the -optimum break will go back onto the contribution list, and control will -effectively pass to the user's output routine. - -We make |type(page_head)==glue_node|, so that an initial glue node on -the current page will not be considered a valid breakpoint. - -@<Initialize the special list...@>= -type(page_head)=glue_node;subtype(page_head)=normal; - -@ The global variable |output_active| is true during the time the -user's output routine is driving \TeX. - -@<Glob...@>= -bool @!output_active; /*are we in the midst of an output routine?*/ - -@ @<Set init...@>= -output_active=false;insert_penalties=0; - -@ The page builder is ready to start a fresh page if we initialize -the following state variables. (However, the page insertion list is initialized -elsewhere.) - -@<Start a new current page@>= -page_contents=empty;page_tail=page_head;link(page_head)=null;@/ -last_glue=max_halfword;last_penalty=0;last_kern=0; -last_node_type=-1; -page_depth=0;page_max_depth=0 - -@ At certain times box 255 is supposed to be void (i.e., |null|), -or an insertion box is supposed to be ready to accept a vertical list. -If not, an error message is printed, and the following subroutine -flushes the unwanted contents, reporting them to the user. - -@p static void box_error(eight_bits @!n) -{@+error();begin_diagnostic(); -print_nl("The following box has been deleted:"); -@.The following...deleted@> -show_box(box(n));end_diagnostic(true); -flush_node_list(box(n));box(n)=null; -} - -@ The following procedure guarantees that a given box register -does not contain an \.{\\hbox}. - -@p static void ensure_vbox(eight_bits @!n) -{@+pointer p; /*the box register contents*/ -p=box(n); -if (p!=null) if (type(p)==hlist_node) - {@+print_err("Insertions can only be added to a vbox"); -@.Insertions can only...@> - help3("Tut tut: You're trying to \\insert into a",@/ - "\\box register that now contains an \\hbox.",@/ - "Proceed, and I'll discard its present contents."); - box_error(n); - } -} - -@ \TeX\ is not always in vertical mode at the time |build_page| -is called; the current mode reflects what \TeX\ should return to, after -the contribution list has been emptied. A call on |build_page| should -be immediately followed by `|goto big_switch|', which is \TeX's central -control point. - -@p -void update_last_values(pointer p) -{@<Update the values of |last_glue|, |last_penalty|, and |last_kern|@>; -} - -@ @d contrib_tail nest[0].tail_field /*tail of the contribution list*/ - -@<Make the contribution list empty...@>= -if (nest_ptr==0) tail=contrib_head; /*vertical mode*/ -else contrib_tail=contrib_head /*other modes*/ - -@ @<Update the values of |last_glue|...@>= -if (last_glue!=max_halfword) delete_glue_ref(last_glue); -last_penalty=0;last_kern=0; -last_node_type=type(p)+1; -if (type(p)==glue_node) - {@+last_glue=glue_ptr(p);add_glue_ref(last_glue); - } -else{@+last_glue=max_halfword; - if (type(p)==penalty_node) last_penalty=penalty(p); - else if (type(p)==kern_node) last_kern=width(p); - } - -@ The code here is an example of a many-way switch into routines that -merge together in different places. Some people call this unstructured -programming, but the author doesn't see much wrong with it, as long as -@^Knuth, Donald Ervin@> -the various labels have a well-understood meaning. - -@<Move node |p| to the current page;...@>= -@<If the current page is empty and node |p| is to be deleted, |goto done1|; otherwise -use node |p| to update the state of the current page; if this node is an insertion, -|goto contribute|; otherwise if this node is not a legal breakpoint, |goto contribute| -or |update_heights|; otherwise set |pi| to the penalty associated with this breakpoint@>; -@<Check if node |p| is a new champion breakpoint; then \(if)if it is time for a page -break, prepare for output, and either fire up the user's output routine and |return| -or ship out the page and |goto done|@>; -if ((type(p) < glue_node)||(type(p) > kern_node)) goto contribute; -update_heights: @<Update the current page measurements with respect to the glue or -kern specified by node~|p|@>; -contribute: @<Make sure that |page_max_depth| is not exceeded@>; -@<Link node |p| into the current page and |goto done|@>; -done1: @<Recycle node |p|@>; -done: - -@ @<Link node |p| into the current page and |goto done|@>= -link(page_tail)=p;page_tail=p; -link(contrib_head)=link(p);link(p)=null;goto done - -@ @<Recycle node |p|@>= -link(contrib_head)=link(p);link(p)=null;flush_node_list(p) - -@ The title of this section is already so long, it seems best to avoid -making it more accurate but still longer, by mentioning the fact that a -kern node at the end of the contribution list will not be contributed until -we know its successor. - -@<If the current page is empty...@>= -switch (type(p)) { -case hlist_node: case vlist_node: case rule_node: if (page_contents < box_there) - @<Initialize the current page, insert the \.{\\topskip} glue ahead of |p|, and -|goto continue|@>@; - else@<Prepare to move a box or rule node to the current page, then |goto contribute|@>@;@+break; -case whatsit_node: @<Prepare to move whatsit |p| to the current page, then |goto contribute|@>; -case glue_node: if (page_contents < box_there) goto done1; - else if (precedes_break(page_tail)) pi=0; - else goto update_heights;@+break; -case kern_node: if (page_contents < box_there) goto done1; - else if (link(p)==null) return; - else if (type(link(p))==glue_node) pi=0; - else goto update_heights;@+break; -case penalty_node: if (page_contents < box_there) goto done1;@+else pi=penalty(p);@+break; -case mark_node: goto contribute; -case ins_node: @<Append an insertion to the current page and |goto contribute|@>@; -default:confusion("page"); -@:this can't happen page}{\quad page@> -} - -@ @<Initialize the current page, insert the \.{\\topskip} glue...@>= -{@+if (page_contents==empty) freeze_page_specs(box_there); -else page_contents=box_there; -q=new_skip_param(top_skip_code); /*now |temp_ptr==glue_ptr(q)|*/ -if (width(temp_ptr) > height(p)) width(temp_ptr)=width(temp_ptr)-height(p); -else width(temp_ptr)=0; -link(q)=p;link(contrib_head)=q;goto resume; -} - -@ @<Prepare to move a box or rule node to the current page...@>= -{@+page_total=page_total+page_depth+height(p); -page_depth=depth(p); -goto contribute; -} - -@ @<Make sure that |page_max_depth| is not exceeded@>= -if (page_depth > page_max_depth) - {@+page_total=@| - page_total+page_depth-page_max_depth;@/ - page_depth=page_max_depth; - } - -@ @<Update the current page measurements with respect to the glue...@>= -if (type(p)==kern_node) q=p; -else{@+q=glue_ptr(p); - page_so_far[2+stretch_order(q)]=@| - page_so_far[2+stretch_order(q)]+stretch(q);@/ - page_shrink=page_shrink+shrink(q); - if ((shrink_order(q)!=normal)&&(shrink(q)!=0)) - {@+@t@>@;@/ - print_err("Infinite glue shrinkage found on current page");@/ -@.Infinite glue shrinkage...@> - help4("The page about to be output contains some infinitely",@/ - "shrinkable glue, e.g., `\\vss' or `\\vskip 0pt minus 1fil'.",@/ - "Such glue doesn't belong there; but you can safely proceed,",@/ - "since the offensive shrinkability has been made finite."); - error(); - r=new_spec(q);shrink_order(r)=normal;delete_glue_ref(q); - glue_ptr(p)=r;q=r; - } - } -page_total=page_total+page_depth+width(q);page_depth=0 - -@ @<Check if node |p| is a new champion breakpoint; then \(if)...@>= -if (pi < inf_penalty) - {@+@<Compute the badness, |b|, of the current page, using |awful_bad| if the box -is too full@>; - if (b < awful_bad) - if (pi <= eject_penalty) c=pi; - else if (b < inf_bad) c=b+pi+insert_penalties; - else c=deplorable; - else c=b; - if (insert_penalties >= 10000) c=awful_bad; -#ifdef @!STAT - if (tracing_pages > 0) @<Display the page break cost@>; -#endif -@;@/ - if (c <= least_page_cost) - {@+best_page_break=p;best_size=page_goal; - least_page_cost=c; - r=link(page_ins_head); - while (r!=page_ins_head) - {@+best_ins_ptr(r)=last_ins_ptr(r); - r=link(r); - } - } - if ((c==awful_bad)||(pi <= eject_penalty)) - {@+fire_up(p); /*output the current page at the best place*/ - if (output_active) return; /*user's output routine will act*/ - goto done; /*the page has been shipped out by default output routine*/ - } - } - -@ @<Display the page break cost@>= -{@+begin_diagnostic();print_nl("%"); -print(" t=");print_totals();@/ -print(" g=");print_scaled(page_goal);@/ -print(" b="); -if (b==awful_bad) print_char('*');@+else print_int(b); -@.*\relax@> -print(" p=");print_int(pi); -print(" c="); -if (c==awful_bad) print_char('*');@+else print_int(c); -if (c <= least_page_cost) print_char('#'); -end_diagnostic(false); -} - -@ @<Compute the badness, |b|, of the current page...@>= -if (page_total < page_goal) - if ((page_so_far[3]!=0)||(page_so_far[4]!=0)||@| - (page_so_far[5]!=0)) b=0; - else b=badness(page_goal-page_total, page_so_far[2]); -else if (page_total-page_goal > page_shrink) b=awful_bad; -else b=badness(page_total-page_goal, page_shrink) - -@ @<Append an insertion to the current page and |goto contribute|@>= -{@+if (page_contents==empty) freeze_page_specs(inserts_only); -n=subtype(p);r=page_ins_head; -while (n >= subtype(link(r))) r=link(r); -n=qo(n); -if (subtype(r)!=qi(n)) - @<Create a page insertion node with |subtype(r)=qi(n)|, and include the glue correction -for box |n| in the current page state@>; -if (type(r)==split_up) insert_penalties=insert_penalties+float_cost(p); -else{@+last_ins_ptr(r)=p; - delta=page_goal-page_total-page_depth+page_shrink; - /*this much room is left if we shrink the maximum*/ - if (count(n)==1000) h=height(p); - else h=x_over_n(height(p), 1000)*count(n); /*this much room is needed*/ - if (((h <= 0)||(h <= delta))&&(height(p)+height(r) <= dimen(n))) - {@+page_goal=page_goal-h;height(r)=height(r)+height(p); - } - else@<Find the best way to split the insertion, and change |type(r)| to |split_up|@>; - } -goto contribute; -} - -@ We take note of the value of \.{\\skip} |n| and the height plus depth -of \.{\\box}~|n| only when the first \.{\\insert}~|n| node is -encountered for a new page. A user who changes the contents of \.{\\box}~|n| -after that first \.{\\insert}~|n| had better be either extremely careful -or extremely lucky, or both. - -@<Create a page insertion node...@>= -{@+q=get_node(page_ins_node_size);link(q)=link(r);link(r)=q;r=q; -subtype(r)=qi(n);type(r)=inserting;ensure_vbox(n); -if (box(n)==null) height(r)=0; -else height(r)=height(box(n))+depth(box(n)); -best_ins_ptr(r)=null;@/ -q=skip(n); -if (count(n)==1000) h=height(r); -else h=x_over_n(height(r), 1000)*count(n); -page_goal=page_goal-h-width(q);@/ -page_so_far[2+stretch_order(q)]=@|page_so_far[2+stretch_order(q)]+stretch(q);@/ -page_shrink=page_shrink+shrink(q); -if ((shrink_order(q)!=normal)&&(shrink(q)!=0)) - {@+print_err("Infinite glue shrinkage inserted from ");print_esc("skip"); -@.Infinite glue shrinkage...@> - print_int(n); - help3("The correction glue for page breaking with insertions",@/ - "must have finite shrinkability. But you may proceed,",@/ - "since the offensive shrinkability has been made finite."); - error(); - } -} - -@ Here is the code that will split a long footnote between pages, in an -emergency. The current situation deserves to be recapitulated: Node |p| -is an insertion into box |n|; the insertion will not fit, in its entirety, -either because it would make the total contents of box |n| greater than -\.{\\dimen} |n|, or because it would make the incremental amount of growth -|h| greater than the available space |delta|, or both. (This amount |h| has -been weighted by the insertion scaling factor, i.e., by \.{\\count} |n| -over 1000.) Now we will choose the best way to break the vlist of the -insertion, using the same criteria as in the \.{\\vsplit} operation. - -@<Find the best way to split the insertion...@>= -{@+if (count(n) <= 0) w=max_dimen; -else{@+w=page_goal-page_total-page_depth; - if (count(n)!=1000) w=x_over_n(w, count(n))*1000; - } -if (w > dimen(n)-height(r)) w=dimen(n)-height(r); -q=vert_break(ins_ptr(p), w, depth(p)); -height(r)=height(r)+best_height_plus_depth; -#ifdef @!STAT -if (tracing_pages > 0) @<Display the insertion split cost@>; -#endif -@;@/ -if (count(n)!=1000) - best_height_plus_depth=x_over_n(best_height_plus_depth, 1000)*count(n); -page_goal=page_goal-best_height_plus_depth; -type(r)=split_up;broken_ptr(r)=q;broken_ins(r)=p; -if (q==null) insert_penalties=insert_penalties+eject_penalty; -else if (type(q)==penalty_node) insert_penalties=insert_penalties+penalty(q); -} - -@ @<Display the insertion split cost@>= -{@+begin_diagnostic();print_nl("% split");print_int(n); -@.split@> -print(" to ");print_scaled(w); -print_char(',');print_scaled(best_height_plus_depth);@/ -print(" p="); -if (q==null) print_int(eject_penalty); -else if (type(q)==penalty_node) print_int(penalty(q)); -else print_char('0'); -end_diagnostic(false); -} - -@ When the page builder has looked at as much material as could appear before -the next page break, it makes its decision. The break that gave minimum -badness will be used to put a completed ``page'' into box 255, with insertions -appended to their other boxes. - -We also set the values of |top_mark|, |first_mark|, and |bot_mark|. The -program uses the fact that |bot_mark!=null| implies |first_mark!=null|; -it also knows that |bot_mark==null| implies |top_mark==first_mark==null|. - -The |fire_up| subroutine prepares to output the current page at the best -place; then it fires up the user's output routine, if there is one, -or it simply ships out the page. There is one parameter, |c|, which represents -the node that was being contributed to the page when the decision to -force an output was made. - -@<Declare the procedure called |fire_up|@>= -static void fire_up(pointer @!c) -{@+ -pointer p, @!q, @!r, @!s; /*nodes being examined and/or changed*/ -pointer @!prev_p; /*predecessor of |p|*/ -int @!n; /*insertion box number*/ -bool @!wait; /*should the present insertion be held over?*/ -int @!save_vbadness; /*saved value of |vbadness|*/ -scaled @!save_vfuzz; /*saved value of |vfuzz|*/ -pointer @!save_split_top_skip; /*saved value of |split_top_skip|*/ -@<Set the value of |output_penalty|@>; -if (bot_mark!=null) - {@+if (top_mark!=null) delete_token_ref(top_mark); - top_mark=bot_mark;add_token_ref(top_mark); - delete_token_ref(first_mark);first_mark=null; - } -@<Put the \(o)optimal current page into box 255, update |first_mark| and |bot_mark|, -append insertions to their boxes, and put the remaining nodes back on the contribution -list@>; -if ((top_mark!=null)&&(first_mark==null)) - {@+first_mark=top_mark;add_token_ref(top_mark); - } -if (output_routine!=null) - if (dead_cycles >= max_dead_cycles) - @<Explain that too many dead cycles have occurred in a row@>@; - else@<Fire up the user's output routine and |return|@>; -@<Perform the default output routine@>; -} - -@ @<Set the value of |output_penalty|@>= -if (type(best_page_break)==penalty_node) - {@+geq_word_define(int_base+output_penalty_code, penalty(best_page_break)); - penalty(best_page_break)=inf_penalty; - } -else geq_word_define(int_base+output_penalty_code, inf_penalty) - -@ As the page is finally being prepared for output, -pointer |p| runs through the vlist, with |prev_p| trailing behind; -pointer |q| is the tail of a list of insertions that -are being held over for a subsequent page. - -@<Put the \(o)optimal current page into box 255...@>= -if (c==best_page_break) best_page_break=null; /*|c| not yet linked in*/ -@<Ensure that box 255 is empty before output@>; -insert_penalties=0; /*this will count the number of insertions held over*/ -save_split_top_skip=split_top_skip; -if (holding_inserts <= 0) - @<Prepare all the boxes involved in insertions to act as queues@>; -q=hold_head;link(q)=null;prev_p=page_head;p=link(prev_p); -while (p!=best_page_break) - {@+if (type(p)==ins_node) - {@+if (holding_inserts <= 0) - @<Either insert the material specified by node |p| into the appropriate box, -or hold it for the next page; also delete node |p| from the current page@>; - } - else if (type(p)==mark_node) @<Update the values of |first_mark| and |bot_mark|@>; - prev_p=p;p=link(prev_p); - } -split_top_skip=save_split_top_skip; -@<Break the current page at node |p|, put it in box~255, and put the remaining nodes -on the contribution list@>; -@<Delete \(t)the page-insertion nodes@>@; - -@ @<Ensure that box 255 is empty before output@>= -if (box(255)!=null) - {@+print_err("");print_esc("box");print("255 is not void"); -@:box255}{\.{\\box255 is not void}@> - help2("You shouldn't use \\box255 except in \\output routines.",@/ - "Proceed, and I'll discard its present contents."); - box_error(255); - } - -@ @<Update the values of |first_mark| and |bot_mark|@>= -{@+if (first_mark==null) - {@+first_mark=mark_ptr(p); - add_token_ref(first_mark); - } -if (bot_mark!=null) delete_token_ref(bot_mark); -bot_mark=mark_ptr(p);add_token_ref(bot_mark); -} - -@ When the following code is executed, the current page runs from node -|link(page_head)| to node |prev_p|, and the nodes from |p| to |page_tail| -are to be placed back at the front of the contribution list. Furthermore -the heldover insertions appear in a list from |link(hold_head)| to |q|; we -will put them into the current page list for safekeeping while the user's -output routine is active. We might have |q==hold_head|; and |p==null| if -and only if |prev_p==page_tail|. Error messages are suppressed within -|vpackage|, since the box might appear to be overfull or underfull simply -because the stretch and shrink from the \.{\\skip} registers for inserts -are not actually present in the box. - -@<Break the current page at node |p|, put it...@>= -if (p!=null) - {@+if (link(contrib_head)==null) - if (nest_ptr==0) tail=page_tail; - else contrib_tail=page_tail; - link(page_tail)=link(contrib_head); - link(contrib_head)=p; - link(prev_p)=null; - } -save_vbadness=vbadness;vbadness=inf_bad; -save_vfuzz=vfuzz;vfuzz=max_dimen; /*inhibit error messages*/ -box(255)=vpackage(link(page_head), best_size, 0, 0, exactly, page_max_depth); -vbadness=save_vbadness;vfuzz=save_vfuzz; -if (last_glue!=max_halfword) delete_glue_ref(last_glue); -@<Start a new current page@>; /*this sets |last_glue=max_halfword|*/ -if (q!=hold_head) - {@+link(page_head)=link(hold_head);page_tail=q; - } - -@ If many insertions are supposed to go into the same box, we want to know -the position of the last node in that box, so that we don't need to waste time -when linking further information into it. The |last_ins_ptr| fields of the -page insertion nodes are therefore used for this purpose during the -packaging phase. - -@<Prepare all the boxes involved in insertions to act as queues@>= -{@+r=link(page_ins_head); -while (r!=page_ins_head) - {@+if (best_ins_ptr(r)!=null) - {@+n=qo(subtype(r));ensure_vbox(n); - if (box(n)==null) box(n)=new_null_box(); - p=box(n)+list_offset; - while (link(p)!=null) p=link(p); - last_ins_ptr(r)=p; - } - r=link(r); - } -} - -@ @<Delete \(t)the page-insertion nodes@>= -r=link(page_ins_head); -while (r!=page_ins_head) - {@+q=link(r);free_node(r, page_ins_node_size);r=q; - } -link(page_ins_head)=page_ins_head - -@ We will set |best_ins_ptr=null| and package the box corresponding to -insertion node~|r|, just after making the final insertion into that box. -If this final insertion is `|split_up|', the remainder after splitting -and pruning (if any) will be carried over to the next page. - -@<Either insert the material specified by node |p| into...@>= -{@+r=link(page_ins_head); -while (subtype(r)!=subtype(p)) r=link(r); -if (best_ins_ptr(r)==null) wait=true; -else{@+wait=false;s=last_ins_ptr(r);link(s)=ins_ptr(p); - if (best_ins_ptr(r)==p) - @<Wrap up the box specified by node |r|, splitting node |p| if called for; set -|wait:=true| if node |p| holds a remainder after splitting@>@; - else{@+while (link(s)!=null) s=link(s); - last_ins_ptr(r)=s; - } - } -@<Either append the insertion node |p| after node |q|, and remove it from the current -page, or delete |node(p)|@>; -} - -@ @<Wrap up the box specified by node |r|, splitting node |p| if...@>= -{@+if (type(r)==split_up) - if ((broken_ins(r)==p)&&(broken_ptr(r)!=null)) - {@+while (link(s)!=broken_ptr(r)) s=link(s); - link(s)=null; - split_top_skip=split_top_ptr(p); - ins_ptr(p)=prune_page_top(broken_ptr(r)); - if (ins_ptr(p)!=null) - {@+temp_ptr=vpack(ins_ptr(p), natural); - height(p)=height(temp_ptr)+depth(temp_ptr); - list_ptr(temp_ptr)=null;flush_node_list(temp_ptr);wait=true; - } - } -best_ins_ptr(r)=null; -n=qo(subtype(r)); -temp_ptr=list_ptr(box(n)); -list_ptr(box(n))=null;flush_node_list(box(n)); -box(n)=vpack(temp_ptr, natural); -} - -@ @<Either append the insertion node |p|...@>= -link(prev_p)=link(p);link(p)=null; -if (wait) - {@+link(q)=p;q=p;incr(insert_penalties); - } -else{@+delete_glue_ref(split_top_ptr(p)); - free_node(p, ins_node_size); - } -p=prev_p - -@ The list of heldover insertions, running from |link(page_head)| to -|page_tail|, must be moved to the contribution list when the user has -specified no output routine. - -@<Perform the default output routine@>= -{@+if (link(page_head)!=null) - {@+if (link(contrib_head)==null) - if (nest_ptr==0) tail=page_tail;@+else contrib_tail=page_tail; - else link(page_tail)=link(contrib_head); - link(contrib_head)=link(page_head); - link(page_head)=null;page_tail=page_head; - } -ship_out(box(255));box(255)=null; -} - -@ @<Explain that too many dead cycles have occurred in a row@>= -{@+print_err("Output loop---");print_int(dead_cycles); -@.Output loop...@> -print(" consecutive dead cycles"); -help3("I've concluded that your \\output is awry; it never does a",@/ -"\\shipout, so I'm shipping \\box255 out myself. Next time",@/ -"increase \\maxdeadcycles if you want me to be more patient!");error(); -} - -@ @<Fire up the user's output routine and |return|@>= -{@+output_active=true; -incr(dead_cycles); -push_nest();mode=-vmode;prev_depth=ignore_depth;mode_line=-line; -begin_token_list(output_routine, output_text); -new_save_level(output_group);normal_paragraph(); -scan_left_brace(); -return; -} - -@ When the user's output routine finishes, it has constructed a vlist -in internal vertical mode, and \TeX\ will do the following: - -@<Resume the page builder after an output routine has come to an end@>= -{@+if ((loc!=null)|| - ((token_type!=output_text)&&(token_type!=backed_up))) - @<Recover from an unbalanced output routine@>; -end_token_list(); /*conserve stack space in case more outputs are triggered*/ -end_graf();unsave();output_active=false;insert_penalties=0;@/ -@<Ensure that box 255 is empty after output@>; -if (tail!=head) /*current list goes after heldover insertions*/ - {@+link(page_tail)=link(head); - page_tail=tail; - } -if (link(page_head)!=null) /*and both go before heldover contributions*/ - {@+if (link(contrib_head)==null) contrib_tail=page_tail; - link(page_tail)=link(contrib_head); - link(contrib_head)=link(page_head); - link(page_head)=null;page_tail=page_head; - } -pop_nest();build_page(); -} - -@ @<Recover from an unbalanced output routine@>= -{@+print_err("Unbalanced output routine"); -@.Unbalanced output routine@> -help2("Your sneaky output routine has problematic {'s and/or }'s.",@/ -"I can't handle that very well; good luck.");error(); -@/do@+{get_token(); -}@+ while (!(loc==null)); -} /*loops forever if reading from a file, since |null==min_halfword <= 0|*/ - -@ @<Ensure that box 255 is empty after output@>= -if (box(255)!=null) - {@+print_err("Output routine didn't use all of "); - print_esc("box");print_int(255); -@.Output routine didn't use...@> - help3("Your \\output commands should empty \\box255,",@/ - "e.g., by saying `\\shipout\\box255'.",@/ - "Proceed; I'll discard its present contents."); - box_error(255); - } - -@* The chief executive. -We come now to the |main_control| routine, which contains the master -switch that causes all the various pieces of \TeX\ to do their things, -in the right order. - -In a sense, this is the grand climax of the program: It applies all the -tools that we have worked so hard to construct. In another sense, this is -the messiest part of the program: It necessarily refers to other pieces -of code all over the place, so that a person can't fully understand what is -going on without paging back and forth to be reminded of conventions that -are defined elsewhere. We are now at the hub of the web, the central nervous -system that touches most of the other parts and ties them together. -@^brain@> - -The structure of |main_control| itself is quite simple. There's a label -called |big_switch|, at which point the next token of input is fetched -using |get_x_token|. Then the program branches at high speed into one of -about 100 possible directions, based on the value of the current -mode and the newly fetched command code; the sum |abs(mode)+cur_cmd| -indicates what to do next. For example, the case `|vmode+letter|' arises -when a letter occurs in vertical mode (or internal vertical mode); this -case leads to instructions that initialize a new paragraph and enter -horizontal mode. - -The big |case| statement that contains this multiway switch has been labeled -|reswitch|, so that the program can |goto reswitch| when the next token -has already been fetched. Most of the cases are quite short; they call -an ``action procedure'' that does the work for that case, and then they -either |goto reswitch| or they ``fall through'' to the end of the |case| -statement, which returns control back to |big_switch|. Thus, |main_control| -is not an extremely large procedure, in spite of the multiplicity of things -it must do; it is small enough to be handled by \PASCAL\ compilers that put -severe restrictions on procedure size. -@!@^action procedure@> - -One case is singled out for special treatment, because it accounts for most -of \TeX's activities in typical applications. The process of reading simple -text and converting it into |char_node| records, while looking for ligatures -and kerns, is part of \TeX's ``inner loop''; the whole program runs -efficiently when its inner loop is fast, so this part has been written -with particular care. - -@ We shall concentrate first on the inner loop of |main_control|, deferring -consideration of the other cases until later. -@^inner loop@> - -@p @t\4@>@<Declare action procedures for use by |main_control|@>@; -@t\4@>@<Declare the procedure called |handle_right_brace|@>@; -static void main_control(void) /*governs \TeX's activities*/ -{@+ - - - - -int @!t; /*general-purpose temporary variable*/ -if (every_job!=null) begin_token_list(every_job, every_job_text); -big_switch: get_x_token();@/ -reswitch: @<Give diagnostic information, if requested@>; -switch (abs(mode)+cur_cmd) { -case hmode+letter: case hmode+other_char: case hmode+char_given: goto main_loop; -case hmode+char_num: {@+scan_char_num();cur_chr=cur_val;goto main_loop;@+} -case hmode+no_boundary: {@+get_x_token(); - if ((cur_cmd==letter)||(cur_cmd==other_char)||(cur_cmd==char_given)|| - (cur_cmd==char_num)) cancel_boundary=true; - goto reswitch; - } -case hmode+spacer: if (space_factor==1000) goto append_normal_space; - else app_space();@+break; -case hmode+ex_space: case mmode+ex_space: goto append_normal_space; -@t\4@>@<Cases of |main_control| that are not part of the inner loop@>@; -} /*of the big |case| statement*/ -goto big_switch; -main_loop: @<Append character |cur_chr| and the following characters (if~any) to the -current hlist in the current font; |goto reswitch| when a non-character has been fetched@>; -append_normal_space: @<Append a normal inter-word space to the current list, then -|goto big_switch|@>; -} - -@ When a new token has just been fetched at |big_switch|, we have an -ideal place to monitor \TeX's activity. -@^debugging@> - -@<Give diagnostic information, if requested@>= -if (interrupt!=0) if (OK_to_interrupt) - {@+back_input();check_interrupt;goto big_switch; - } -#ifdef @!DEBUG -if (panicking) check_mem(false);@; -#endif -if (tracing_commands > 0) show_cur_cmd_chr() - -@ The following part of the program was first written in a structured -manner, according to the philosophy that ``premature optimization is -the root of all evil.'' Then it was rearranged into pieces of -spaghetti so that the most common actions could proceed with little or -no redundancy. - -The original unoptimized form of this algorithm resembles the -|reconstitute| procedure, which was described earlier in connection with -hyphenation. Again we have an implied ``cursor'' between characters -|cur_l| and |cur_r|. The main difference is that the |lig_stack| can now -contain a charnode as well as pseudo-ligatures; that stack is now -usually nonempty, because the next character of input (if any) has been -appended to it. In |main_control| we have -$$|cur_r|=\cases{|character(lig_stack)|,&if |lig_stack > null|;\cr - |font_bchar[cur_font]|,&otherwise;\cr}$$ -except when |character(lig_stack)==font_false_bchar[cur_font]|. -Several additional global variables are needed. - -@<Glob...@>= -static internal_font_number @!main_f; /*the current font*/ -static four_quarters @!main_i; /*character information bytes for |cur_l|*/ -static four_quarters @!main_j; /*ligature/kern command*/ -static font_index @!main_k; /*index into |font_info|*/ -static pointer @!main_p; /*temporary register for list manipulation*/ -static int @!main_s; /*space factor value*/ -static halfword @!bchar; /*boundary character of current font, or |non_char|*/ -static halfword @!false_bchar; /*nonexistent character matching |bchar|, or |non_char|*/ -static bool @!cancel_boundary; /*should the left boundary be ignored?*/ -static bool @!ins_disc; /*should we insert a discretionary node?*/ - -@ The boolean variables of the main loop are normally false, and always reset -to false before the loop is left. That saves us the extra work of initializing -each time. - -@<Set init...@>= -ligature_present=false;cancel_boundary=false;lft_hit=false;rt_hit=false; -ins_disc=false; - -@ We leave the |space_factor| unchanged if |sf_code(cur_chr)==0|; otherwise we -set it equal to |sf_code(cur_chr)|, except that it should never change -from a value less than 1000 to a value exceeding 1000. The most common -case is |sf_code(cur_chr)==1000|, so we want that case to be fast. - -The overall structure of the main loop is presented here. Some program labels -are inside the individual sections. -@^inner loop@> - -@d adjust_space_factor @t@>@;@/ - main_s=sf_code(cur_chr); - if (main_s==1000) space_factor=1000; - else if (main_s < 1000) - {@+if (main_s > 0) space_factor=main_s; - } - else if (space_factor < 1000) space_factor=1000; - else space_factor=main_s - -@<Append character |cur_chr|...@>= -adjust_space_factor;@/ -main_f=cur_font; -bchar=font_bchar[main_f];false_bchar=font_false_bchar[main_f]; -if (mode > 0) if (language!=clang) fix_language(); -fast_get_avail(lig_stack);font(lig_stack)=main_f;cur_l=qi(cur_chr); -character(lig_stack)=cur_l;@/ -cur_q=tail; -if (cancel_boundary) - {@+cancel_boundary=false;main_k=non_address; - } -else main_k=bchar_label[main_f]; -if (main_k==non_address) goto main_loop_move2; /*no left boundary processing*/ -cur_r=cur_l;cur_l=non_char; -goto main_lig_loop1; /*begin with cursor after left boundary*/ -@# -main_loop_wrapup: @<Make a ligature node, if |ligature_present|; insert a null discretionary, -if appropriate@>; -main_loop_move: @<If the cursor is immediately followed by the right boundary, |goto -reswitch|; if it's followed by an invalid character, |goto big_switch|; otherwise -move the cursor one step to the right and |goto main_lig_loop|@>; -main_loop_lookahead: @<Look ahead for another character, or leave |lig_stack| empty -if there's none there@>; -main_lig_loop: @<If there's a ligature/kern command relevant to |cur_l| and |cur_r|, -adjust the text appropriately; exit to |main_loop_wrapup|@>; -main_loop_move_lig: @<Move the cursor past a pseudo-ligature, then |goto main_loop_lookahead| -or |main_lig_loop|@>@; - -@ If |link(cur_q)| is nonnull when |wrapup| is invoked, |cur_q| points to -the list of characters that were consumed while building the ligature -character~|cur_l|. - -A discretionary break is not inserted for an explicit hyphen when we are in -restricted horizontal mode. In particular, this avoids putting discretionary -nodes inside of other discretionaries. -@^inner loop@> - -@d pack_lig(X) /*the parameter is either |rt_hit| or |false|*/ - {@+main_p=new_ligature(main_f, cur_l, link(cur_q)); - if (lft_hit) - {@+subtype(main_p)=2;lft_hit=false; - } - if (X) if (lig_stack==null) - {@+incr(subtype(main_p));rt_hit=false; - } - link(cur_q)=main_p;tail=main_p;ligature_present=false; - } - -@d wrapup(A) if (cur_l < non_char) - {@+if (link(cur_q) > null) - if (character(tail)==qi(hyphen_char[main_f])) ins_disc=true; - if (ligature_present) pack_lig(A); - if (ins_disc) - {@+ins_disc=false; - if (mode > 0) tail_append(new_disc()); - } - } - -@<Make a ligature node, if |ligature_present|;...@>= -wrapup(rt_hit) - -@ @<If the cursor is immediately followed by the right boundary...@>= -@^inner loop@> -if (lig_stack==null) goto reswitch; -cur_q=tail;cur_l=character(lig_stack); -main_loop_move1: if (!is_char_node(lig_stack)) goto main_loop_move_lig; -main_loop_move2: if ((cur_chr < font_bc[main_f])||(cur_chr > font_ec[main_f])) - {@+char_warning(main_f, cur_chr);free_avail(lig_stack);goto big_switch; - } -main_i=char_info(main_f, cur_l); -if (!char_exists(main_i)) - {@+char_warning(main_f, cur_chr);free_avail(lig_stack);goto big_switch; - } -link(tail)=lig_stack;tail=lig_stack /*|main_loop_lookahead| is next*/ - -@ Here we are at |main_loop_move_lig|. -When we begin this code we have |cur_q==tail| and |cur_l==character(lig_stack)|. - -@<Move the cursor past a pseudo-ligature...@>= -main_p=lig_ptr(lig_stack); -if (main_p > null) tail_append(main_p); /*append a single character*/ -temp_ptr=lig_stack;lig_stack=link(temp_ptr); -free_node(temp_ptr, small_node_size); -main_i=char_info(main_f, cur_l);ligature_present=true; -if (lig_stack==null) - if (main_p > null) goto main_loop_lookahead; - else cur_r=bchar; -else cur_r=character(lig_stack); -goto main_lig_loop - -@ The result of \.{\\char} can participate in a ligature or kern, so we must -look ahead for it. - -@<Look ahead for another character...@>= -get_next(); /*set only |cur_cmd| and |cur_chr|, for speed*/ -if (cur_cmd==letter) goto main_loop_lookahead1; -if (cur_cmd==other_char) goto main_loop_lookahead1; -if (cur_cmd==char_given) goto main_loop_lookahead1; -x_token(); /*now expand and set |cur_cmd|, |cur_chr|, |cur_tok|*/ -if (cur_cmd==letter) goto main_loop_lookahead1; -if (cur_cmd==other_char) goto main_loop_lookahead1; -if (cur_cmd==char_given) goto main_loop_lookahead1; -if (cur_cmd==char_num) - {@+scan_char_num();cur_chr=cur_val;goto main_loop_lookahead1; - } -if (cur_cmd==no_boundary) bchar=non_char; -cur_r=bchar;lig_stack=null;goto main_lig_loop; -main_loop_lookahead1: adjust_space_factor; -fast_get_avail(lig_stack);font(lig_stack)=main_f; -cur_r=qi(cur_chr);character(lig_stack)=cur_r; -if (cur_r==false_bchar) cur_r=non_char /*this prevents spurious ligatures*/ - -@ Even though comparatively few characters have a lig/kern program, several -of the instructions here count as part of \TeX's inner loop, since a -@^inner loop@> -potentially long sequential search must be performed. For example, tests with -Computer Modern Roman showed that about 40 per cent of all characters -actually encountered in practice had a lig/kern program, and that about four -lig/kern commands were investigated for every such character. - -At the beginning of this code we have |main_i==char_info(main_f, cur_l)|. - -@<If there's a ligature/kern command...@>= -if (char_tag(main_i)!=lig_tag) goto main_loop_wrapup; -if (cur_r==non_char) goto main_loop_wrapup; -main_k=lig_kern_start(main_f, main_i);main_j=font_info[main_k].qqqq; -if (skip_byte(main_j) <= stop_flag) goto main_lig_loop2; -main_k=lig_kern_restart(main_f, main_j); -main_lig_loop1: main_j=font_info[main_k].qqqq; -main_lig_loop2: if (next_char(main_j)==cur_r) - if (skip_byte(main_j) <= stop_flag) - @<Do ligature or kern command, returning to |main_lig_loop| or |main_loop_wrapup| -or |main_loop_move|@>; -if (skip_byte(main_j)==qi(0)) incr(main_k); -else{@+if (skip_byte(main_j) >= stop_flag) goto main_loop_wrapup; - main_k=main_k+qo(skip_byte(main_j))+1; - } -goto main_lig_loop1 - -@ When a ligature or kern instruction matches a character, we know from -|read_font_info| that the character exists in the font, even though we -haven't verified its existence in the normal way. - -This section could be made into a subroutine, if the code inside -|main_control| needs to be shortened. - -\chardef\@@='174 % vertical line to indicate character retention - -@<Do ligature or kern command...@>= -{@+if (op_byte(main_j) >= kern_flag) - {@+wrapup(rt_hit); - tail_append(new_kern(char_kern(main_f, main_j)));goto main_loop_move; - } -if (cur_l==non_char) lft_hit=true; -else if (lig_stack==null) rt_hit=true; -check_interrupt; /*allow a way out in case there's an infinite ligature loop*/ -switch (op_byte(main_j)) { -case qi(1): case qi(5): {@+cur_l=rem_byte(main_j); /*\.{=:\@@}, \.{=:\@@>}*/ - main_i=char_info(main_f, cur_l);ligature_present=true; - } @+break; -case qi(2): case qi(6): {@+cur_r=rem_byte(main_j); /*\.{\@@=:}, \.{\@@=:>}*/ - if (lig_stack==null) /*right boundary character is being consumed*/ - {@+lig_stack=new_lig_item(cur_r);bchar=non_char; - } - else if (is_char_node(lig_stack)) /*|link(lig_stack)==null|*/ - {@+main_p=lig_stack;lig_stack=new_lig_item(cur_r); - lig_ptr(lig_stack)=main_p; - } - else character(lig_stack)=cur_r; - } @+break; -case qi(3): {@+cur_r=rem_byte(main_j); /*\.{\@@=:\@@}*/ - main_p=lig_stack;lig_stack=new_lig_item(cur_r); - link(lig_stack)=main_p; - } @+break; -case qi(7): case qi(11): {@+wrapup(false); /*\.{\@@=:\@@>}, \.{\@@=:\@@>>}*/ - cur_q=tail;cur_l=rem_byte(main_j); - main_i=char_info(main_f, cur_l);ligature_present=true; - } @+break; -default:{@+cur_l=rem_byte(main_j);ligature_present=true; /*\.{=:}*/ - if (lig_stack==null) goto main_loop_wrapup; - else goto main_loop_move1; - } -} -if (op_byte(main_j) > qi(4)) - if (op_byte(main_j)!=qi(7)) goto main_loop_wrapup; -if (cur_l < non_char) goto main_lig_loop; -main_k=bchar_label[main_f];goto main_lig_loop1; -} - -@ The occurrence of blank spaces is almost part of \TeX's inner loop, -@^inner loop@> -since we usually encounter about one space for every five non-blank characters. -Therefore |main_control| gives second-highest priority to ordinary spaces. - -When a glue parameter like \.{\\spaceskip} is set to `\.{0pt}', we will -see to it later that the corresponding glue specification is precisely -|zero_glue|, not merely a pointer to some specification that happens -to be full of zeroes. Therefore it is simple to test whether a glue parameter -is zero or~not. - -@<Append a normal inter-word space...@>= -if (space_skip==zero_glue) - {@+@<Find the glue specification, |main_p|, for text spaces in the current font@>; - temp_ptr=new_glue(main_p); - } -else temp_ptr=new_param_glue(space_skip_code); -link(tail)=temp_ptr;tail=temp_ptr; -goto big_switch - -@ Having |font_glue| allocated for each text font saves both time and memory. -If any of the three spacing parameters are subsequently changed by the -use of \.{\\fontdimen}, the |find_font_dimen| procedure deallocates the -|font_glue| specification allocated here. - -@<Find the glue specification...@>= -{@+main_p=font_glue[cur_font]; -if (main_p==null) - {@+main_p=new_spec(zero_glue);main_k=param_base[cur_font]+space_code; - width(main_p)=font_info[main_k].sc; /*that's |space(cur_font)|*/ - stretch(main_p)=font_info[main_k+1].sc; /*and |space_stretch(cur_font)|*/ - shrink(main_p)=font_info[main_k+2].sc; /*and |space_shrink(cur_font)|*/ - font_glue[cur_font]=main_p; - } -} - -@ @<Declare act...@>= -static void app_space(void) /*handle spaces when |space_factor!=1000|*/ -{@+pointer @!q; /*glue node*/ -if ((space_factor >= 2000)&&(xspace_skip!=zero_glue)) - q=new_param_glue(xspace_skip_code); -else{@+if (space_skip!=zero_glue) main_p=space_skip; - else@<Find the glue specification...@>; - main_p=new_spec(main_p); - @<Modify the glue specification in |main_p| according to the space factor@>; - q=new_glue(main_p);glue_ref_count(main_p)=null; - } -link(tail)=q;tail=q; -} - -@ @<Modify the glue specification in |main_p| according to the space factor@>= -if (space_factor >= 2000) width(main_p)=width(main_p)+extra_space(cur_font); -stretch(main_p)=xn_over_d(stretch(main_p), space_factor, 1000); -shrink(main_p)=xn_over_d(shrink(main_p), 1000, space_factor) - -@ Whew---that covers the main loop. We can now proceed at a leisurely -pace through the other combinations of possibilities. - -@d any_mode(A) case vmode+A: case hmode+A: case mmode+A /*for mode-independent commands*/ - -@<Cases of |main_control| that are not part of the inner loop@>= -any_mode(relax): case vmode+spacer: case mmode+spacer: case mmode+no_boundary: do_nothing; -any_mode(ignore_spaces): {@+@<Get the next non-blank non-call...@>; - goto reswitch; - } -case vmode+stop: if (its_all_over()) return;@+break; /*this is the only way out*/ -@t\4@>@<Forbidden cases detected in |main_control|@>@+@, any_mode(mac_param): - report_illegal_case();@+break; -@<Math-only cases in non-math modes, or vice versa@>: insert_dollar_sign();@+break; -@t\4@>@<Cases of |main_control| that build boxes and lists@>@; -@t\4@>@<Cases of |main_control| that don't depend on |mode|@>@; -@t\4@>@<Cases of |main_control| that are for extensions to \TeX@>@; - -@ Here is a list of cases where the user has probably gotten into or out of math -mode by mistake. \TeX\ will insert a dollar sign and rescan the current token. - -@d non_math(A) case vmode+A: case hmode+A - -@<Math-only cases in non-math modes...@>= -non_math(sup_mark): non_math(sub_mark): non_math(math_char_num): -non_math(math_given): non_math(math_comp): non_math(delim_num): -non_math(left_right): non_math(above): non_math(radical): -non_math(math_style): non_math(math_choice): non_math(vcenter): -non_math(non_script): non_math(mkern): non_math(limit_switch): -non_math(mskip): non_math(math_accent): -case mmode+endv: case mmode+par_end: case mmode+stop: case mmode+vskip: case mmode+un_vbox: -case mmode+valign: case mmode+hrule - -@ @<Declare action...@>= -static void insert_dollar_sign(void) -{@+back_input();cur_tok=math_shift_token+'$'; -print_err("Missing $ inserted"); -@.Missing \$ inserted@> -help2("I've inserted a begin-math/end-math symbol since I think",@/ -"you left one out. Proceed, with fingers crossed.");ins_error(); -} - -@ When erroneous situations arise, \TeX\ usually issues an error message -specific to the particular error. For example, `\.{\\noalign}' should -not appear in any mode, since it is recognized by the |align_peek| routine -in all of its legitimate appearances; a special error message is given -when `\.{\\noalign}' occurs elsewhere. But sometimes the most appropriate -error message is simply that the user is not allowed to do what he or she -has attempted. For example, `\.{\\moveleft}' is allowed only in vertical mode, -and `\.{\\lower}' only in non-vertical modes. Such cases are enumerated -here and in the other sections referred to under `See also \dots.' - -@<Forbidden cases...@>= -case vmode+vmove: case hmode+hmove: case mmode+hmove: any_mode(last_item): - -@ The `|you_cant|' procedure prints a line saying that the current command -is illegal in the current mode; it identifies these things symbolically. - -@<Declare action...@>= -static void you_cant(void) -{@+print_err("You can't use `"); -@.You can't use x in y mode@> -print_cmd_chr(cur_cmd, cur_chr); -print("' in ");print_mode(mode); -} - -@ @<Declare act...@>= -static void report_illegal_case(void) -{@+you_cant(); -help4("Sorry, but I'm not programmed to handle this case;",@/ -"I'll just pretend that you didn't ask for it.",@/ -"If you're in the wrong mode, you might be able to",@/ -"return to the right one by typing `I}' or `I$' or `I\\par'.");@/ -error(); -} - -@ Some operations are allowed only in privileged modes, i.e., in cases -that |mode > 0|. The |privileged| function is used to detect violations -of this rule; it issues an error message and returns |false| if the -current |mode| is negative. - -@<Declare act...@>= -static bool privileged(void) -{@+if (mode > 0) return true; -else{@+report_illegal_case();return false; - } -} - -@ Either \.{\\dump} or \.{\\end} will cause |main_control| to enter the -endgame, since both of them have `|stop|' as their command code. - -@<Put each...@>= -primitive("end", stop, 0);@/ -@!@:end\_}{\.{\\end} primitive@> -primitive("dump", stop, 1);@/ -@!@:dump\_}{\.{\\dump} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case stop: if (chr_code==1) print_esc("dump");@+else print_esc("end");@+break; - -@ We don't want to leave |main_control| immediately when a |stop| command -is sensed, because it may be necessary to invoke an \.{\\output} routine -several times before things really grind to a halt. (The output routine -might even say `\.{\\gdef\\end\{...\}}', to prolong the life of the job.) -Therefore |its_all_over| is |true| only when the current page -and contribution list are empty, and when the last output was not a -``dead cycle.'' - -@<Declare act...@>= -static bool its_all_over(void) /*do this when \.{\\end} or \.{\\dump} occurs*/ -{@+ -if (privileged()) - {@+if ((page_head==page_tail)&&(head==tail)&&(dead_cycles==0)) - {@+return true; - } - back_input(); /*we will try to end again after ejecting residual material*/ - tail_append(new_set_node()); - set_extent(tail)=new_xdimen(dimen_par(hsize_code), - dimen_par_hfactor(hsize_code),dimen_par_vfactor(hsize_code)); - tail_append(new_glue(fill_glue)); - tail_append(new_penalty(2*(eject_penalty)));@/ - build_page(); /*append \.{\\hbox to \\hsize\{\}\\vfill\\penalty-'10000000000}*/ - } -return false; -} - -@* Building boxes and lists. -The most important parts of |main_control| are concerned with \TeX's -chief mission of box-making. We need to control the activities that put -entries on vlists and hlists, as well as the activities that convert -those lists into boxes. All of the necessary machinery has already been -developed; it remains for us to ``push the buttons'' at the right times. - -@ As an introduction to these routines, let's consider one of the simplest -cases: What happens when `\.{\\hrule}' occurs in vertical mode, or -`\.{\\vrule}' in horizontal mode or math mode? The code in |main_control| -is short, since the |scan_rule_spec| routine already does most of what is -required; thus, there is no need for a special action procedure. - -Note that baselineskip calculations are disabled after a rule in vertical -mode, by setting |prev_depth=ignore_depth|. - -@<Cases of |main_control| that build...@>= -case vmode+hrule: case hmode+vrule: case mmode+vrule: {@+tail_append(scan_rule_spec()); - if (abs(mode)==vmode) prev_depth=ignore_depth; - else if (abs(mode)==hmode) space_factor=1000; - } @+break; - -@ The processing of things like \.{\\hskip} and \.{\\vskip} is slightly -more complicated. But the code in |main_control| is very short, since -it simply calls on the action routine |append_glue|. Similarly, \.{\\kern} -activates |append_kern|. - -@<Cases of |main_control| that build...@>= -case vmode+vskip: case hmode+hskip: case mmode+hskip: case mmode+mskip: append_glue();@+break; -any_mode(kern): case mmode+mkern: append_kern();@+break; - -@ The |hskip| and |vskip| command codes are used for control sequences -like \.{\\hss} and \.{\\vfil} as well as for \.{\\hskip} and \.{\\vskip}. -The difference is in the value of |cur_chr|. - -@d fil_code 0 /*identifies \.{\\hfil} and \.{\\vfil}*/ -@d fill_code 1 /*identifies \.{\\hfill} and \.{\\vfill}*/ -@d ss_code 2 /*identifies \.{\\hss} and \.{\\vss}*/ -@d fil_neg_code 3 /*identifies \.{\\hfilneg} and \.{\\vfilneg}*/ -@d skip_code 4 /*identifies \.{\\hskip} and \.{\\vskip}*/ -@d mskip_code 5 /*identifies \.{\\mskip}*/ - -@<Put each...@>= -primitive("hskip", hskip, skip_code);@/ -@!@:hskip\_}{\.{\\hskip} primitive@> -primitive("hfil", hskip, fil_code); -@!@:hfil\_}{\.{\\hfil} primitive@> -primitive("hfill", hskip, fill_code);@/ -@!@:hfill\_}{\.{\\hfill} primitive@> -primitive("hss", hskip, ss_code); -@!@:hss\_}{\.{\\hss} primitive@> -primitive("hfilneg", hskip, fil_neg_code);@/ -@!@:hfil\_neg\_}{\.{\\hfilneg} primitive@> -primitive("vskip", vskip, skip_code);@/ -@!@:vskip\_}{\.{\\vskip} primitive@> -primitive("vfil", vskip, fil_code); -@!@:vfil\_}{\.{\\vfil} primitive@> -primitive("vfill", vskip, fill_code);@/ -@!@:vfill\_}{\.{\\vfill} primitive@> -primitive("vss", vskip, ss_code); -@!@:vss\_}{\.{\\vss} primitive@> -primitive("vfilneg", vskip, fil_neg_code);@/ -@!@:vfil\_neg\_}{\.{\\vfilneg} primitive@> -primitive("mskip", mskip, mskip_code);@/ -@!@:mskip\_}{\.{\\mskip} primitive@> -primitive("kern", kern, explicit); -@!@:kern\_}{\.{\\kern} primitive@> -primitive("mkern", mkern, mu_glue);@/ -@!@:mkern\_}{\.{\\mkern} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case hskip: switch (chr_code) { - case skip_code: print_esc("hskip");@+break; - case fil_code: print_esc("hfil");@+break; - case fill_code: print_esc("hfill");@+break; - case ss_code: print_esc("hss");@+break; - default:print_esc("hfilneg"); - } @+break; -case vskip: switch (chr_code) { - case skip_code: print_esc("vskip");@+break; - case fil_code: print_esc("vfil");@+break; - case fill_code: print_esc("vfill");@+break; - case ss_code: print_esc("vss");@+break; - default:print_esc("vfilneg"); - } @+break; -case mskip: print_esc("mskip");@+break; -case kern: print_esc("kern");@+break; -case mkern: print_esc("mkern");@+break; - -@ All the work relating to glue creation has been relegated to the -following subroutine. It does not call |build_page|, because it is -used in at least one place where that would be a mistake. - -@<Declare action...@>= -static void append_glue(void) -{@+small_number s; /*modifier of skip command*/ -s=cur_chr; -switch (s) { -case fil_code: cur_val=fil_glue;@+break; -case fill_code: cur_val=fill_glue;@+break; -case ss_code: cur_val=ss_glue;@+break; -case fil_neg_code: cur_val=fil_neg_glue;@+break; -case skip_code: scan_glue(glue_val);@+break; -case mskip_code: scan_glue(mu_val); -} /*now |cur_val| points to the glue specification*/ -tail_append(new_glue(cur_val)); -if (s >= skip_code) - {@+decr(glue_ref_count(cur_val)); - if (s > skip_code) subtype(tail)=mu_glue; - } -} - -@ @<Declare act...@>= -static void append_kern(void) -{@+quarterword s; /*|subtype| of the kern node*/ -s=cur_chr;scan_dimen(s==mu_glue, false, false); -tail_append(new_kern(cur_val));subtype(tail)=s; -} - -@ Many of the actions related to box-making are triggered by the appearance -of braces in the input. For example, when the user says `\.{\\hbox} -\.{to} \.{100pt\{$\langle\,\hbox{\rm hlist}\,\rangle$\}}' in vertical mode, -the information about the box size (100pt, |exactly|) is put onto |save_stack| -with a level boundary word just above it, and |cur_group=adjusted_hbox_group|; -\TeX\ enters restricted horizontal mode to process the hlist. The right -brace eventually causes |save_stack| to be restored to its former state, -at which time the information about the box size (100pt, |exactly|) is -available once again; a box is packaged and we leave restricted horizontal -mode, appending the new box to the current list of the enclosing mode -(in this case to the current list of vertical mode), followed by any -vertical adjustments that were removed from the box by |hpack|. - -The next few sections of the program are therefore concerned with the -treatment of left and right curly braces. - -@ If a left brace occurs in the middle of a page or paragraph, it simply -introduces a new level of grouping, and the matching right brace will not have -such a drastic effect. Such grouping affects neither the mode nor the -current list. - -@<Cases of |main_control| that build...@>= -non_math(left_brace): new_save_level(simple_group);@+break; -any_mode(begin_group): new_save_level(semi_simple_group);@+break; -any_mode(end_group): if (cur_group==semi_simple_group) unsave(); - else off_save();@+break; - -@ We have to deal with errors in which braces and such things are not -properly nested. Sometimes the user makes an error of commission by -inserting an extra symbol, but sometimes the user makes an error of omission. -\TeX\ can't always tell one from the other, so it makes a guess and tries -to avoid getting into a loop. - -The |off_save| routine is called when the current group code is wrong. It tries -to insert something into the user's input that will help clean off -the top level. - -@<Declare act...@>= -static void off_save(void) -{@+pointer p; /*inserted token*/ -if (cur_group==bottom_level) - @<Drop current token and complain that it was unmatched@>@; -else{@+back_input();p=get_avail();link(temp_head)=p; - print_err("Missing "); - @<Prepare to insert a token that matches |cur_group|, and print what it is@>; - print(" inserted");ins_list(link(temp_head)); - help5("I've inserted something that you may have forgotten.",@/ - "(See the <inserted text> above.)",@/ - "With luck, this will get me unwedged. But if you",@/ - "really didn't forget anything, try typing `2' now; then",@/ - "my insertion and my current dilemma will both disappear."); - error(); - } -} - -@ At this point, |link(temp_head)==p|, a pointer to an empty one-word node. - -@<Prepare to insert a token that matches |cur_group|...@>= -switch (cur_group) { -case semi_simple_group: {@+info(p)=cs_token_flag+frozen_end_group; - print_esc("endgroup"); -@.Missing \\endgroup inserted@> - } @+break; -case math_shift_group: {@+info(p)=math_shift_token+'$';print_char('$'); -@.Missing \$ inserted@> - } @+break; -case math_left_group: {@+info(p)=cs_token_flag+frozen_right;link(p)=get_avail(); - p=link(p);info(p)=other_token+'.';print_esc("right."); -@.Missing \\right\hbox{.} inserted@> -@^null delimiter@> - } @+break; -default:{@+info(p)=right_brace_token+'}';print_char('}'); -@.Missing \} inserted@> - } -} - -@ @<Drop current token and complain that it was unmatched@>= -{@+print_err("Extra ");print_cmd_chr(cur_cmd, cur_chr); -@.Extra x@> -help1("Things are pretty mixed up, but I think the worst is over.");@/ -error(); -} - -@ The routine for a |right_brace| character branches into many subcases, -since a variety of things may happen, depending on |cur_group|. Some -types of groups are not supposed to be ended by a right brace; error -messages are given in hopes of pinpointing the problem. Most branches -of this routine will be filled in later, when we are ready to understand -them; meanwhile, we must prepare ourselves to deal with such errors. - -@<Cases of |main_control| that build...@>= -any_mode(right_brace): handle_right_brace();@+break; - -@ @<Declare the procedure called |handle_right_brace|@>= -static void handle_right_brace(void) -{@+pointer p, @!q; /*for short-term use*/ -scaled @!d; /*holds |split_max_depth| in |insert_group|*/ -int @!f; /*holds |floating_penalty| in |insert_group|*/ -switch (cur_group) { -case simple_group: unsave();@+break; -case bottom_level: {@+print_err("Too many }'s"); -@.Too many \}'s@> - help2("You've closed more groups than you opened.",@/ - "Such booboos are generally harmless, so keep going.");error(); - } @+break; -case semi_simple_group: case math_shift_group: case math_left_group: extra_right_brace();@+break; -@t\4@>@<Cases of |handle_right_brace| where a |right_brace| triggers a delayed action@>@; -default:confusion("rightbrace"); -@:this can't happen rightbrace}{\quad rightbrace@> -} -} - -@ @<Declare act...@>= -static void extra_right_brace(void) -{@+print_err("Extra }, or forgotten "); -@.Extra \}, or forgotten x@> -switch (cur_group) { -case semi_simple_group: print_esc("endgroup");@+break; -case math_shift_group: print_char('$');@+break; -case math_left_group: print_esc("right"); -} @/ -help5("I've deleted a group-closing symbol because it seems to be",@/ -"spurious, as in `$x}$'. But perhaps the } is legitimate and",@/ -"you forgot something else, as in `\\hbox{$x}'. In such cases",@/ -"the way to recover is to insert both the forgotten and the",@/ -"deleted material, e.g., by typing `I$}'.");error(); -incr(align_state); -} - -@ Here is where we clear the parameters that are supposed to revert to their -default values after every paragraph and when internal vertical mode is entered. - -@<Declare act...@>= -void normal_paragraph(void) -{@+if (looseness!=0) eq_word_define(int_base+looseness_code, 0); -if (hang_indent!=0) eq_word_define(dimen_base+hang_indent_code, 0); -if (hang_after!=1) eq_word_define(int_base+hang_after_code, 1); -if (par_shape_ptr!=null) eq_define(par_shape_loc, shape_ref, null); -if (inter_line_penalties_ptr!=null) - eq_define(inter_line_penalties_loc, shape_ref, null); -} - -@ Now let's turn to the question of how \.{\\hbox} is treated. We actually -need to consider also a slightly larger context, since constructions like -`\.{\\setbox3=}\penalty0\.{\\hbox...}' and -`\.{\\leaders}\penalty0\.{\\hbox...}' and -`\.{\\lower3.8pt\\hbox...}' -are supposed to invoke quite -different actions after the box has been packaged. Conversely, -constructions like `\.{\\setbox3=}' can be followed by a variety of -different kinds of boxes, and we would like to encode such things in an -efficient way. - -In other words, there are two problems: to represent the context of a box, -and to represent its type. - -The first problem is solved by putting a ``context code'' on the |save_stack|, -just below the two entries that give the dimensions produced by |scan_spec|. -The context code is either a (signed) shift amount, or it is a large -integer | >= box_flag|, where |box_flag==@t$2^{30}$@>|. Codes |box_flag| through -|global_box_flag-1| represent `\.{\\setbox0}' through `\.{\\setbox32767}'; -codes |global_box_flag| through |ship_out_flag-1| represent -`\.{\\global\\setbox0}' through `\.{\\global\\setbox32767}'; -code |ship_out_flag| represents `\.{\\shipout}'; and codes |leader_flag| -through |leader_flag+2| represent `\.{\\leaders}', `\.{\\cleaders}', -and `\.{\\xleaders}'. - -The second problem is solved by giving the command code |make_box| to all -control sequences that produce a box, and by using the following |chr_code| -values to distinguish between them: |box_code|, |copy_code|, |last_box_code|, -|vsplit_code|, |vtop_code|, |vtop_code+vmode|, and |vtop_code+hmode|, where -the latter two are used to denote \.{\\vbox} and \.{\\hbox}, respectively. - -@d box_flag 010000000000 /*context code for `\.{\\setbox0}'*/ -@d global_box_flag 010000100000 /*context code for `\.{\\global\\setbox0}'*/ -@d ship_out_flag 010000200000 /*context code for `\.{\\shipout}'*/ -@d leader_flag 010000200001 /*context code for `\.{\\leaders}'*/ -@d box_code 0 /*|chr_code| for `\.{\\box}'*/ -@d copy_code 1 /*|chr_code| for `\.{\\copy}'*/ -@d last_box_code 2 /*|chr_code| for `\.{\\lastbox}'*/ -@d vsplit_code 3 /*|chr_code| for `\.{\\vsplit}'*/ -@d vtop_code 4 /*|chr_code| for `\.{\\vtop}'*/ - -@<Put each...@>= -primitive("moveleft", hmove, 1); -@!@:move\_left\_}{\.{\\moveleft} primitive@> -primitive("moveright", hmove, 0);@/ -@!@:move\_right\_}{\.{\\moveright} primitive@> -primitive("raise", vmove, 1); -@!@:raise\_}{\.{\\raise} primitive@> -primitive("lower", vmove, 0); -@!@:lower\_}{\.{\\lower} primitive@> -@# -primitive("box", make_box, box_code); -@!@:box\_}{\.{\\box} primitive@> -primitive("copy", make_box, copy_code); -@!@:copy\_}{\.{\\copy} primitive@> -primitive("lastbox", make_box, last_box_code); -@!@:last\_box\_}{\.{\\lastbox} primitive@> -primitive("vsplit", make_box, vsplit_code); -@!@:vsplit\_}{\.{\\vsplit} primitive@> -primitive("vtop", make_box, vtop_code);@/ -@!@:vtop\_}{\.{\\vtop} primitive@> -primitive("vbox", make_box, vtop_code+vmode); -@!@:vbox\_}{\.{\\vbox} primitive@> -primitive("hbox", make_box, vtop_code+hmode);@/ -@!@:hbox\_}{\.{\\hbox} primitive@> -primitive("shipout", leader_ship, a_leaders-1); /*|ship_out_flag==leader_flag-1|*/ -@!@:ship\_out\_}{\.{\\shipout} primitive@> -primitive("leaders", leader_ship, a_leaders); -@!@:leaders\_}{\.{\\leaders} primitive@> -primitive("cleaders", leader_ship, c_leaders); -@!@:c\_leaders\_}{\.{\\cleaders} primitive@> -primitive("xleaders", leader_ship, x_leaders); -@!@:x\_leaders\_}{\.{\\xleaders} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case hmove: if (chr_code==1) print_esc("moveleft");@+else print_esc("moveright");@+break; -case vmove: if (chr_code==1) print_esc("raise");@+else print_esc("lower");@+break; -case make_box: switch (chr_code) { - case box_code: print_esc("box");@+break; - case copy_code: print_esc("copy");@+break; - case last_box_code: print_esc("lastbox");@+break; - case vsplit_code: print_esc("vsplit");@+break; - case vtop_code: print_esc("vtop");@+break; - case vtop_code+vmode: print_esc("vbox");@+break; - default:print_esc("hbox"); - } @+break; -case leader_ship: if (chr_code==a_leaders) print_esc("leaders"); - else if (chr_code==c_leaders) print_esc("cleaders"); - else if (chr_code==x_leaders) print_esc("xleaders"); - else print_esc("shipout");@+break; - -@ Constructions that require a box are started by calling |scan_box| with -a specified context code. The |scan_box| routine verifies -that a |make_box| command comes next and then it calls |begin_box|. - -@<Cases of |main_control| that build...@>= -case vmode+hmove: case hmode+vmove: case mmode+vmove: {@+t=cur_chr; - scan_normal_dimen; - if (t==0) scan_box(cur_val);@+else scan_box(-cur_val); - } @+break; -any_mode(leader_ship): scan_box(leader_flag-a_leaders+cur_chr);@+break; -any_mode(make_box): begin_box(0);@+break; - -@ The global variable |cur_box| will point to a newly made box. If the box -is void, we will have |cur_box==null|. Otherwise we will have -|type(cur_box)==hlist_node| or |vlist_node| or |rule_node|; the |rule_node| -case can occur only with leaders. - -@<Glob...@>= -static pointer @!cur_box; /*box to be placed into its context*/ - -@ The |box_end| procedure does the right thing with |cur_box|, if -|box_context| represents the context as explained above. - -@<Declare act...@>= -static void box_end(int @!box_context) -{@+pointer p; /*|ord_noad| for new box in math mode*/ -small_number @!a; /*global prefix*/ -if (box_context < box_flag) @<Append box |cur_box| to the current list, shifted by -|box_context|@>@; -else if (box_context < ship_out_flag) @<Store \(c)|cur_box| in a box register@>@; -else if (cur_box!=null) - if (box_context > ship_out_flag) @<Append a new leader node that uses |cur_box|@>@; - else ship_out(cur_box); -} - -@ The global variable |adjust_tail| will be non-null if and only if the -current box might include adjustments that should be appended to the -current vertical list. - -@<Append box |cur_box| to the current...@>= -{@+if (cur_box!=null) - {@+shift_amount(cur_box)=box_context; - if (abs(mode)==vmode) - {@+append_to_vlist(cur_box); - if (adjust_tail!=null) - {@+if (adjust_head!=adjust_tail) - {@+link(tail)=link(adjust_head);tail=adjust_tail; - } - adjust_tail=null; - } - if (mode > 0) build_page(); - } - else{@+if (abs(mode)==hmode) space_factor=1000; - else{@+p=new_noad(); - math_type(nucleus(p))=sub_box; - info(nucleus(p))=cur_box;cur_box=p; - } - link(tail)=cur_box;tail=cur_box; - } - } -} - -@ @<Store \(c)|cur_box| in a box register@>= -{@+if (box_context < global_box_flag) - {@+cur_val=box_context-box_flag;a=0; - } -else{@+cur_val=box_context-global_box_flag;a=4; - } -if (cur_val < 256) define(box_base+cur_val, box_ref, cur_box); -else sa_def_box; -} - -@ @<Append a new leader node...@>= -{@+@<Get the next non-blank non-relax...@>; -if (((cur_cmd==hskip)&&(abs(mode)!=vmode))||@| - ((cur_cmd==vskip)&&(abs(mode)==vmode))) - {@+append_glue();subtype(tail)=box_context-(leader_flag-a_leaders); - leader_ptr(tail)=cur_box; - } -else{@+print_err("Leaders not followed by proper glue"); -@.Leaders not followed by...@> - help3("You should say `\\leaders <box or rule><hskip or vskip>'.",@/ - "I found the <box or rule>, but there's no suitable",@/ - "<hskip or vskip>, so I'm ignoring these leaders.");back_error(); - flush_node_list(cur_box); - } -} - -@ Now that we can see what eventually happens to boxes, we can consider -the first steps in their creation. The |begin_box| routine is called when -|box_context| is a context specification, |cur_chr| specifies the type of -box desired, and |cur_cmd==make_box|. - -@<Declare act...@>= -static void begin_box(int @!box_context) -{@+ -pointer @!p, @!q; /*run through the current list*/ -int @!m; /*the length of a replacement list*/ -halfword @!k; /*0 or |vmode| or |hmode|*/ -halfword @!n; /*a box number*/ -switch (cur_chr) { -case box_code: {@+scan_register_num();fetch_box(cur_box); - change_box(null); /*the box becomes void, at the same level*/ - } @+break; -case copy_code: {@+scan_register_num();fetch_box(q);cur_box=copy_node_list(q); - } @+break; -case last_box_code: @<If the current list ends with a box node, delete it from the -list and make |cur_box| point to it; otherwise set |cur_box:=null|@>@;@+break; -case vsplit_code: @<Split off part of a vertical box, make |cur_box| point to it@>@;@+break; -default:@<Initiate the construction of an hbox or vbox, then |return|@>@; -} @/ -box_end(box_context); /*in simple cases, we use the box immediately*/ -} - -@ Note that the condition |!is_char_node(tail)| implies that |head!=tail|, -since |head| is a one-word node. - -@<If the current list ends with a box node, delete it...@>= -{@+cur_box=null; -if (abs(mode)==mmode) - {@+you_cant();help1("Sorry; this \\lastbox will be void.");error(); - } -else if ((mode==vmode)&&(head==tail)) - {@+you_cant(); - help2("Sorry...I usually can't take things from the current page.",@/ - "This \\lastbox will therefore be void.");error(); - } -else{@+if (!is_char_node(tail)) - if ((type(tail)==hlist_node)||(type(tail)==vlist_node)) - @<Remove the last box, unless it's part of a discretionary@>; - } -} - -@ @<Remove the last box...@>= -{@+q=head; -@/do@+{p=q; -if (!is_char_node(q)) if (type(q)==disc_node) - {@+for (m=1; m<=replace_count(q); m++) p=link(p); - if (p==tail) goto done; - } -q=link(p); -}@+ while (!(q==tail)); -cur_box=tail;shift_amount(cur_box)=0; -tail=p;link(p)=null; -done: ;} - -@ Here we deal with things like `\.{\\vsplit 13 to 100pt}'. - -@<Split off part of a vertical box, make |cur_box| point to it@>= -{@+scan_register_num();n=cur_val; -if (!scan_keyword("to")) -@.to@> - {@+print_err("Missing `to' inserted"); -@.Missing `to' inserted@> - help2("I'm working on `\\vsplit<box number> to <dimen>';",@/ - "will look for the <dimen> next.");error(); - } -scan_normal_dimen; -cur_box=vsplit(n, cur_val); -} - -@ Here is where we enter restricted horizontal mode or internal vertical -mode, in order to make a box. - -@<Initiate the construction of an hbox or vbox, then |return|@>= -{@+k=cur_chr-vtop_code;saved(0)=box_context; -if (k==hmode) - if ((box_context < box_flag)&&(abs(mode)==vmode)) - scan_spec(adjusted_hbox_group, true); - else scan_spec(hbox_group, true); -else{@+if (k==vmode) scan_spec(vbox_group, true); - else{@+scan_spec(vtop_group, true);k=vmode; - } - normal_paragraph(); - } -push_nest();mode=-k; -if (k==vmode) - {@+prev_depth=ignore_depth; - if (every_vbox!=null) begin_token_list(every_vbox, every_vbox_text); - } -else{@+space_factor=1000; - if (every_hbox!=null) begin_token_list(every_hbox, every_hbox_text); - } -return; -} - -@ @<Declare act...@>= -static void scan_box(int @!box_context) - /*the next input should specify a box or perhaps a rule*/ -{@+@<Get the next non-blank non-relax...@>; -if (cur_cmd==make_box) begin_box(box_context); -else if ((box_context >= leader_flag)&&((cur_cmd==hrule)||(cur_cmd==vrule))) - {@+cur_box=scan_rule_spec();box_end(box_context); - } -else{@+@t@>@;@/ - print_err("A <box> was supposed to be here");@/ -@.A <box> was supposed to...@> - help3("I was expecting to see \\hbox or \\vbox or \\copy or \\box or",@/ - "something like that. So you might find something missing in",@/ - "your output. But keep trying; you can fix this later.");back_error(); - } -} - -@ When the right brace occurs at the end of an \.{\\hbox} or \.{\\vbox} or -\.{\\vtop} construction, the |package| routine comes into action. We might -also have to finish a paragraph that hasn't ended. - -@<Cases of |handle...@>= -case hbox_group: package(0);@+break; -case adjusted_hbox_group: {@+adjust_tail=adjust_head;package(0); - } @+break; -case vbox_group: {@+end_graf();package(0); - } @+break; -case vtop_group: {@+end_graf();package(vtop_code); - } @+break; - -@ @<Declare action...@>= -static void package(small_number @!c) -{@+scaled h; /*height of box*/ -pointer @!p; /*first node in a box*/ -scaled @!d; /*max depth*/ -d=box_max_depth;unsave();save_ptr=save_ptr-3; -if (mode==-hmode) cur_box=hpack(link(head), saved(2), saved_hfactor(2), saved_vfactor(2), saved(1)); -else{@+cur_box=vpackage(link(head), saved(2), saved_hfactor(2), saved_vfactor(2), saved(1), d); - if (c==vtop_code) @<Readjust the height and depth of |cur_box|, for \.{\\vtop}@>; - } -pop_nest();box_end(saved(0)); -} - -@ The height of a `\.{\\vtop}' box is inherited from the first item on its list, -if that item is an |hlist_node|, |vlist_node|, or |rule_node|; otherwise -the \.{\\vtop} height is zero. - - -@<Readjust the height...@>= -{@+h=0;p=list_ptr(cur_box); -if (p!=null) if (type(p) <= rule_node) h=height(p); -depth(cur_box)=depth(cur_box)-h+height(cur_box);height(cur_box)=h; -} - -@ A paragraph begins when horizontal-mode material occurs in vertical mode, -or when the paragraph is explicitly started by `\.{\\indent}' or -`\.{\\noindent}'. - -@<Put each...@>= -primitive("indent", start_par, 1); -@!@:indent\_}{\.{\\indent} primitive@> -primitive("noindent", start_par, 0); -@!@:no\_indent\_}{\.{\\noindent} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case start_par: if (chr_code==0) print_esc("noindent");@+else print_esc("indent");@+break; - -@ @<Cases of |main_control| that build...@>= -case vmode+start_par: new_graf(cur_chr > 0);@+break; -case vmode+letter: case vmode+other_char: case vmode+char_num: case vmode+char_given: - case vmode+math_shift: case vmode+un_hbox: case vmode+vrule: - case vmode+accent: case vmode+discretionary: case vmode+hskip: case vmode+valign: - case vmode+ex_space: case vmode+no_boundary: @t@>@;@/ - {@+back_input();new_graf(true); - } @+break; - -@ @<Declare act...@>= -static small_number norm_min(int @!h) -{@+if (h <= 0) return 1;@+else if (h >= 63) return 63;@+ -else return h; -} -@# -static void new_graf(bool @!indented) -{@+prev_graf=0; -if ((mode==vmode)||(head!=tail)) - tail_append(new_param_glue(par_skip_code)); -push_nest();mode=hmode;space_factor=1000;set_cur_lang;clang=cur_lang; -prev_graf=(norm_min(left_hyphen_min)*0100+norm_min(right_hyphen_min)) - *0200000+cur_lang; -if (indented) - {@+tail=new_null_box();link(head)=tail;width(tail)=par_indent;@+ - } -if (every_par!=null) begin_token_list(every_par, every_par_text); -if (nest_ptr==1) build_page(); /*put |par_skip| glue on current page*/ -} - -@ @<Cases of |main_control| that build...@>= -case hmode+start_par: case mmode+start_par: indent_in_hmode();@+break; - -@ @<Declare act...@>= -static void indent_in_hmode(void) -{@+pointer p, @!q; -if (cur_chr > 0) /*\.{\\indent}*/ - {@+p=new_null_box();width(p)=par_indent; - if (abs(mode)==hmode) space_factor=1000; - else{@+q=new_noad();math_type(nucleus(q))=sub_box; - info(nucleus(q))=p;p=q; - } - tail_append(p); - } -} - -@ A paragraph ends when a |par_end| command is sensed, or when we are in -horizontal mode when reaching the right brace of vertical-mode routines -like \.{\\vbox}, \.{\\insert}, or \.{\\output}. - -@<Cases of |main_control| that build...@>= -case vmode+par_end: {@+normal_paragraph(); - if (mode > 0) build_page(); - } @+break; -case hmode+par_end: {@+if (align_state < 0) off_save(); /*this tries to - recover from an alignment that didn't end properly*/ - end_graf(); /*this takes us to the enclosing mode, if |mode > 0|*/ - if (mode==vmode) build_page(); - } @+break; -case hmode+stop: case hmode+vskip: case hmode+hrule: case hmode+un_vbox: case hmode+halign: head_for_vmode();@+break; - -@ @<Declare act...@>= -static void head_for_vmode(void) -{@+if (mode < 0) - if (cur_cmd!=hrule) off_save(); - else{@+print_err("You can't use `"); - print_esc("hrule");print("' here except with leaders"); -@.You can't use \\hrule...@> - help2("To put a horizontal rule in an hbox or an alignment,",@/ - "you should use \\leaders or \\hrulefill (see The TeXbook)."); - error(); - } -else{@+back_input();cur_tok=par_token;back_input();token_type=inserted; - } -} - -@ @<Declare act...@>= -void end_graf(void) -{@+if (mode==hmode) - {@+if (head==tail) pop_nest(); /*null paragraphs are ignored*/ - else hline_break(widow_penalty); - normal_paragraph(); - error_count=0; - } -} - -@ Insertion and adjustment and mark nodes are constructed by the following -pieces of the program. - -@<Cases of |main_control| that build...@>= -any_mode(insert): case hmode+vadjust: case mmode+vadjust: begin_insert_or_adjust();@+break; -any_mode(mark): make_mark();@+break; - -@ @<Forbidden...@>= -case vmode+vadjust: - -@ @<Declare act...@>= -static void begin_insert_or_adjust(void) -{@+if (cur_cmd==vadjust) cur_val=255; -else{@+scan_eight_bit_int(); - if (cur_val==255) - {@+print_err("You can't ");print_esc("insert");print_int(255); -@.You can't \\insert255@> - help1("I'm changing to \\insert0; box 255 is special."); - error();cur_val=0; - } - } -saved(0)=cur_val;incr(save_ptr); -new_save_level(insert_group);scan_left_brace();normal_paragraph(); -push_nest();mode=-vmode;prev_depth=ignore_depth; -} - -@ @<Cases of |handle...@>= -case insert_group: {@+end_graf();q=split_top_skip;add_glue_ref(q); - d=split_max_depth;f=floating_penalty;unsave();decr(save_ptr); - /*now |saved(0)| is the insertion number, or 255 for |vadjust|*/ - p=link(head);pop_nest(); - if (saved(0) < 255) - {@+tail_append(get_node(ins_node_size)); - type(tail)=ins_node;subtype(tail)=qi(saved(0)); - height(tail)=0; ins_ptr(tail)=p; hget_stream_no(subtype(tail)); - split_top_ptr(tail)=q;depth(tail)=d;float_cost(tail)=f; - } - else{@+tail_append(get_node(small_node_size)); - type(tail)=adjust_node;@/ - subtype(tail)=0; /*the |subtype| is not used*/ - adjust_ptr(tail)=p;delete_glue_ref(q); - } - if (nest_ptr==0) build_page(); - } @+break; -case output_group: @<Resume the page builder...@>@;@+break; -case page_group: hfinish_page_group();@+break; -case stream_group: hfinish_stream_group();@+break; -case stream_before_group: hfinish_stream_before_group();@+break; -case stream_after_group: hfinish_stream_after_group();@+break; -case outline_group: hfinish_outline_group();@+break; - -@ @<Declare act...@>= -static void make_mark(void) -{@+pointer p; /*new node*/ -p=scan_toks(false, true);p=get_node(small_node_size); -type(p)=mark_node;subtype(p)=0; /*the |subtype| is not used*/ -mark_ptr(p)=def_ref;link(tail)=p;tail=p; -} - -@ Penalty nodes get into a list via the |break_penalty| command. -@^penalties@> - -@<Cases of |main_control| that build...@>= -any_mode(break_penalty): append_penalty();@+break; - -@ @<Declare action...@>= -static void append_penalty(void) -{@+scan_int();tail_append(new_penalty(cur_val)); -if (mode==vmode) build_page(); -} - -@ The |remove_item| command removes a penalty, kern, or glue node if it -appears at the tail of the current list, using a brute-force linear scan. -Like \.{\\lastbox}, this command is not allowed in vertical mode (except -internal vertical mode), since the current list in vertical mode is sent -to the page builder. But if we happen to be able to implement it in -vertical mode, we do. - -@<Cases of |main_control| that build...@>= -any_mode(remove_item): delete_last();@+break; - -@ When |delete_last| is called, |cur_chr| is the |type| of node that -will be deleted, if present. - -@<Declare action...@>= -static void delete_last(void) -{@+ -pointer @!p, @!q; /*run through the current list*/ -int @!m; /*the length of a replacement list*/ -if ((mode==vmode)&&(tail==head)) - @<Apologize for inability to do the operation now, unless \.{\\unskip} follows non-glue@>@; -else{@+if (!is_char_node(tail)) if (type(tail)==cur_chr) - {@+q=head; - @/do@+{p=q; - if (!is_char_node(q)) if (type(q)==disc_node) - {@+for (m=1; m<=replace_count(q); m++) p=link(p); - if (p==tail) return; - } - q=link(p); - }@+ while (!(q==tail)); - link(p)=null;flush_node_list(tail);tail=p; - } - } -} - -@ @<Apologize for inability to do the operation...@>= -{@+if ((cur_chr!=glue_node)||(last_glue!=max_halfword)) - {@+you_cant(); - help2("Sorry...I usually can't take things from the current page.",@/ - "Try `I\\vskip-\\lastskip' instead."); - if (cur_chr==kern_node) help_line[0]= - ("Try `I\\kern-\\lastkern' instead."); - else if (cur_chr!=glue_node) help_line[0]=@| - ("Perhaps you can make the output routine do it."); - error(); - } -} - -@ @<Put each...@>= -primitive("unpenalty", remove_item, penalty_node);@/ -@!@:un\_penalty\_}{\.{\\unpenalty} primitive@> -primitive("unkern", remove_item, kern_node);@/ -@!@:un\_kern\_}{\.{\\unkern} primitive@> -primitive("unskip", remove_item, glue_node);@/ -@!@:un\_skip\_}{\.{\\unskip} primitive@> -primitive("unhbox", un_hbox, box_code);@/ -@!@:un\_hbox\_}{\.{\\unhbox} primitive@> -primitive("unhcopy", un_hbox, copy_code);@/ -@!@:un\_hcopy\_}{\.{\\unhcopy} primitive@> -primitive("unvbox", un_vbox, box_code);@/ -@!@:un\_vbox\_}{\.{\\unvbox} primitive@> -primitive("unvcopy", un_vbox, copy_code);@/ -@!@:un\_vcopy\_}{\.{\\unvcopy} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case remove_item: if (chr_code==glue_node) print_esc("unskip"); - else if (chr_code==kern_node) print_esc("unkern"); - else print_esc("unpenalty");@+break; -case un_hbox: if (chr_code==copy_code) print_esc("unhcopy"); - else print_esc("unhbox");@+break; -case un_vbox: if (chr_code==copy_code) print_esc("unvcopy"); - else print_esc("unvbox");@+break; - -@ The |un_hbox| and |un_vbox| commands unwrap one of the 256 current boxes. - -@<Cases of |main_control| that build...@>= -case vmode+un_vbox: case hmode+un_hbox: case mmode+un_hbox: unpackage();@+break; - -@ @<Declare act...@>= -static void unpackage(void) -{@+ -pointer p; /*the box*/ -int @!c; /*should we copy?*/ -c=cur_chr;scan_register_num();fetch_box(p); -if (p==null) return; -if ((abs(mode)==mmode)||@| - ((abs(mode)==vmode)&& (type(p)!=vlist_node) - && (type(p)!=whatsit_node || (subtype(p)!=vset_node - && subtype(p)!=vpack_node))) ||@| - ((abs(mode)==hmode)&& (type(p)!=hlist_node) - && (type(p)!=whatsit_node || ( subtype(p)!=hset_node - && subtype(p)!=hpack_node)))) - {@+print_err("Incompatible list can't be unboxed"); -@.Incompatible list...@> - help3("Sorry, Pandora. (You sneaky devil.)",@/ - "I refuse to unbox an \\hbox in vertical mode or vice versa.",@/ - "And I can't open any boxes in math mode.");@/ - error();return; - } -if (c==copy_code) link(tail)=copy_node_list(list_ptr(p)); -else{@+link(tail)=list_ptr(p);change_box(null); - list_ptr(p)=null;flush_node_list(p); - } -while (link(tail)!=null) tail=link(tail); -} - -@ @<Forbidden...@>=case vmode+ital_corr: - -@ Italic corrections are converted to kern nodes when the |ital_corr| command -follows a character. In math mode the same effect is achieved by appending -a kern of zero here, since italic corrections are supplied later. - -@<Cases of |main_control| that build...@>= -case hmode+ital_corr: append_italic_correction();@+break; -case mmode+ital_corr: tail_append(new_kern(0))@;@+break; - -@ @<Declare act...@>= -static void append_italic_correction(void) -{@+ -pointer p; /*|char_node| at the tail of the current list*/ -internal_font_number @!f; /*the font in the |char_node|*/ -if (tail!=head) - {@+if (is_char_node(tail)) p=tail; - else if (type(tail)==ligature_node) p=lig_char(tail); - else return; - f=font(p); - tail_append(new_kern(char_italic(f, char_info(f, character(p))))); - subtype(tail)=explicit; - } -} - -@ Discretionary nodes are easy in the common case `\.{\\-}', but in the -general case we must process three braces full of items. - -@<Put each...@>= -primitive("-", discretionary, 1); -@!@:Single-character primitives -}{\quad\.{\\-}@> -primitive("discretionary", discretionary, 0); -@!@:discretionary\_}{\.{\\discretionary} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case discretionary: if (chr_code==1) - print_esc("-");@+else print_esc("discretionary");@+break; - -@ @<Cases of |main_control| that build...@>= -case hmode+discretionary: case mmode+discretionary: append_discretionary();@+break; - -@ The space factor does not change when we append a discretionary node, -but it starts out as 1000 in the subsidiary lists. - -@<Declare act...@>= -static void append_discretionary(void) -{@+int c; /*hyphen character*/ -tail_append(new_disc()); -if (cur_chr==1) - {@+c=hyphen_char[cur_font]; - if (c >= 0) if (c < 256) pre_break(tail)=new_character(cur_font, c); - } -else{@+incr(save_ptr);saved(-1)=0;new_save_level(disc_group); - scan_left_brace();push_nest();mode=-hmode;space_factor=1000; - } -} - -@ The three discretionary lists are constructed somewhat as if they were -hboxes. A~subroutine called |build_discretionary| handles the transitions. -(This is sort of fun.) - -@<Cases of |handle...@>= -case disc_group: build_discretionary();@+break; - -@ @<Declare act...@>= -static void build_discretionary(void) -{@+ -pointer p, @!q; /*for link manipulation*/ -int @!n; /*length of discretionary list*/ -unsave(); -@<Prune the current list, if necessary, until it contains only |char_node|, |kern_node|, -|hlist_node|, |vlist_node|, |rule_node|, and |ligature_node| items; set |n| to the -length of the list, and set |q| to the list's tail@>; -p=link(head);pop_nest(); -switch (saved(-1)) { -case 0: pre_break(tail)=p;@+break; -case 1: post_break(tail)=p;@+break; -case 2: @<Attach list |p| to the current list, and record its length; then finish -up and |return|@>; -} /*there are no other cases*/ -incr(saved(-1));new_save_level(disc_group);scan_left_brace(); -push_nest();mode=-hmode;space_factor=1000; -} - -@ @<Attach list |p| to the current...@>= -{@+if ((n > 0)&&(abs(mode)==mmode)) - {@+print_err("Illegal math ");print_esc("discretionary"); -@.Illegal math \\disc...@> - help2("Sorry: The third part of a discretionary break must be",@/ - "empty, in math formulas. I had to delete your third part."); - flush_node_list(p);n=0;error(); - } -else link(tail)=p; -if (n <= 0x7F) set_replace_count(tail,n); -else{@+print_err("Discretionary list is too long"); -@.Discretionary list is too long@> - help2("Wow---I never thought anybody would tweak me here.",@/ - "You can't seriously need such a huge discretionary list?"); - error(); - } -if (n > 0) tail=q; -decr(save_ptr);return; -} - -@ During this loop, |p==link(q)| and there are |n| items preceding |p|. - -@<Prune the current list, if necessary...@>= -q=head;p=link(q);n=0; -while (p!=null) - {@+if (!is_char_node(p)) if (type(p) > rule_node) - if (type(p)!=kern_node) if (type(p)!=ligature_node) - {@+print_err("Improper discretionary list"); -@.Improper discretionary list@> - help1("Discretionary lists must contain only boxes and kerns.");@/ - error(); - begin_diagnostic(); - print_nl("The following discretionary sublist has been deleted:"); -@.The following...deleted@> - show_box(p); - end_diagnostic(true); - flush_node_list(p);link(q)=null;goto done; - } - q=p;p=link(q);incr(n); - } -done: - -@ We need only one more thing to complete the horizontal mode routines, namely -the \.{\\accent} primitive. - -@<Cases of |main_control| that build...@>= -case hmode+accent: make_accent();@+break; - -@ The positioning of accents is straightforward but tedious. Given an accent -of width |a|, designed for characters of height |x| and slant |s|; -and given a character of width |w|, height |h|, and slant |t|: We will shift -the accent down by |x-h|, and we will insert kern nodes that have the effect of -centering the accent over the character and shifting the accent to the -right by $\delta={1\over2}(w-a)+h\cdot t-x\cdot s$. If either character is -absent from the font, we will simply use the other, without shifting. - -@<Declare act...@>= -static void make_accent(void) -{@+double s, @!t; /*amount of slant*/ -pointer @!p, @!q, @!r; /*character, box, and kern nodes*/ -internal_font_number @!f; /*relevant font*/ -scaled @!a, @!h, @!x, @!w, @!delta; /*heights and widths, as explained above*/ -four_quarters @!i; /*character information*/ -scan_char_num();f=cur_font;p=new_character(f, cur_val); -if (p!=null) - {@+x=x_height(f);s=slant(f)/float_constant(65536); -@^real division@> - a=char_width(f, char_info(f, character(p)));@/ - do_assignments();@/ - @<Create a character node |q| for the next character, but set |q:=null| if problems -arise@>; - if (q!=null) @<Append the accent with appropriate kerns, then set |p:=q|@>; - link(tail)=p;tail=p;space_factor=1000; - } -} - -@ @<Create a character node |q| for the next...@>= -q=null;f=cur_font; -if ((cur_cmd==letter)||(cur_cmd==other_char)||(cur_cmd==char_given)) - q=new_character(f, cur_chr); -else if (cur_cmd==char_num) - {@+scan_char_num();q=new_character(f, cur_val); - } -else back_input() - -@ The kern nodes appended here must be distinguished from other kerns, lest -they be wiped away by the hyphenation algorithm or by a previous line break. - -The two kerns are computed with (machine-dependent) |double| arithmetic, but -their sum is machine-independent; the net effect is machine-independent, -because the user cannot remove these nodes nor access them via \.{\\lastkern}. - -@<Append the accent with appropriate kerns...@>= -{@+t=slant(f)/float_constant(65536); -@^real division@> -i=char_info(f, character(q)); -w=char_width(f, i);h=char_height(f, height_depth(i)); -if (h!=x) /*the accent must be shifted up or down*/ - {@+p=hpack(p, natural);shift_amount(p)=x-h; - } -delta=round((w-a)/float_constant(2)+h*t-x*s); -@^real multiplication@> -@^real addition@> -r=new_kern(delta);subtype(r)=acc_kern;link(tail)=r;link(r)=p; -tail=new_kern(-a-delta);subtype(tail)=acc_kern;link(p)=tail;p=q; -} - -@ When `\.{\\cr}' or `\.{\\span}' or a tab mark comes through the scanner -into |main_control|, it might be that the user has foolishly inserted -one of them into something that has nothing to do with alignment. But it is -far more likely that a left brace or right brace has been omitted, since -|get_next| takes actions appropriate to alignment only when `\.{\\cr}' -or `\.{\\span}' or tab marks occur with |align_state==0|. The following -program attempts to make an appropriate recovery. - -@<Cases of |main_control| that build...@>= -any_mode(car_ret): any_mode(tab_mark): align_error();@+break; -any_mode(no_align): no_align_error();@+break; -any_mode(omit): omit_error();@+break; - -@ @<Declare act...@>= -static void align_error(void) -{@+if (abs(align_state) > 2) - @<Express consternation over the fact that no alignment is in progress@>@; -else{@+back_input(); - if (align_state < 0) - {@+print_err("Missing { inserted"); -@.Missing \{ inserted@> - incr(align_state);cur_tok=left_brace_token+'{'; - } - else{@+print_err("Missing } inserted"); -@.Missing \} inserted@> - decr(align_state);cur_tok=right_brace_token+'}'; - } - help3("I've put in what seems to be necessary to fix",@/ - "the current column of the current alignment.",@/ - "Try to go on, since this might almost work.");ins_error(); - } -} - -@ @<Express consternation...@>= -{@+print_err("Misplaced ");print_cmd_chr(cur_cmd, cur_chr); -@.Misplaced \&@> -@.Misplaced \\span@> -@.Misplaced \\cr@> -if (cur_tok==tab_token+'&') - {@+help6("I can't figure out why you would want to use a tab mark",@/ - "here. If you just want an ampersand, the remedy is",@/ - "simple: Just type `I\\&' now. But if some right brace",@/ - "up above has ended a previous alignment prematurely,",@/ - "you're probably due for more error messages, and you",@/ - "might try typing `S' now just to see what is salvageable."); - } -else{@+help5("I can't figure out why you would want to use a tab mark",@/ - "or \\cr or \\span just now. If something like a right brace",@/ - "up above has ended a previous alignment prematurely,",@/ - "you're probably due for more error messages, and you",@/ - "might try typing `S' now just to see what is salvageable."); - } -error(); -} - -@ The help messages here contain a little white lie, since \.{\\noalign} -and \.{\\omit} are allowed also after `\.{\\noalign\{...\}}'. - -@<Declare act...@>= -static void no_align_error(void) -{@+print_err("Misplaced ");print_esc("noalign"); -@.Misplaced \\noalign@> -help2("I expect to see \\noalign only after the \\cr of",@/ - "an alignment. Proceed, and I'll ignore this case.");error(); -} -static void omit_error(void) -{@+print_err("Misplaced ");print_esc("omit"); -@.Misplaced \\omit@> -help2("I expect to see \\omit only after tab marks or the \\cr of",@/ - "an alignment. Proceed, and I'll ignore this case.");error(); -} - -@ We've now covered most of the abuses of \.{\\halign} and \.{\\valign}. -Let's take a look at what happens when they are used correctly. - -@<Cases of |main_control| that build...@>= -case vmode+halign: case hmode+valign: init_align();@+break; -case mmode+halign: if (privileged()) - if (cur_group==math_shift_group) init_align(); - else off_save();@+break; -case vmode+endv: case hmode+endv: do_endv();@+break; - -@ An |align_group| code is supposed to remain on the |save_stack| -during an entire alignment, until |fin_align| removes it. - -A devious user might force an |endv| command to occur just about anywhere; -we must defeat such hacks. - -@<Declare act...@>= -static void do_endv(void) -{@+base_ptr=input_ptr;input_stack[base_ptr]=cur_input; -while ((input_stack[base_ptr].index_field!=v_template)&& - (input_stack[base_ptr].loc_field==null)&& - (input_stack[base_ptr].state_field==token_list)) decr(base_ptr); -if ((input_stack[base_ptr].index_field!=v_template)|| - (input_stack[base_ptr].loc_field!=null)|| - (input_stack[base_ptr].state_field!=token_list)) - fatal_error("(interwoven alignment preambles are not allowed)"); -@.interwoven alignment preambles...@> - if (cur_group==align_group) - {@+end_graf(); - if (fin_col()) fin_row(); - } -else off_save(); -} - -@ @<Cases of |handle_right_brace|...@>= -case align_group: {@+back_input();cur_tok=cs_token_flag+frozen_cr; - print_err("Missing ");print_esc("cr");print(" inserted"); -@.Missing \\cr inserted@> - help1("I'm guessing that you meant to end an alignment here."); - ins_error(); - } @+break; - -@ @<Cases of |handle_right_brace|...@>= -case no_align_group: {@+end_graf();unsave();align_peek(); - } @+break; - -@ Finally, \.{\\endcsname} is not supposed to get through to |main_control|. - -@<Cases of |main_control| that build...@>= -any_mode(end_cs_name): cs_error();@+break; - -@ @<Declare act...@>= -static void cs_error(void) -{@+print_err("Extra ");print_esc("endcsname"); -@.Extra \\endcsname@> -help1("I'm ignoring this, since I wasn't doing a \\csname."); -error(); -} - -@* Building math lists. -The routines that \TeX\ uses to create mlists are similar to those we have -just seen for the generation of hlists and vlists. But it is necessary to -make ``noads'' as well as nodes, so the reader should review the -discussion of math mode data structures before trying to make sense out of -the following program. - -Here is a little routine that needs to be done whenever a subformula -is about to be processed. The parameter is a code like |math_group|. - -@<Declare act...@>= -static void push_math(group_code @!c) -{@+push_nest();mode=-mmode;incompleat_noad=null;new_save_level(c); -} - -@ We get into math mode from horizontal mode when a `\.\$' (i.e., a -|math_shift| character) is scanned. We must check to see whether this -`\.\$' is immediately followed by another, in case display math mode is -called for. - -@<Cases of |main_control| that build...@>= -case hmode+math_shift: init_math();@+break; - -@ @<Declare act...@>= -static void init_math(void) -{@+ -scaled w; /*new or partial |pre_display_size|*/ -scaled @!l; /*new |display_width|*/ -scaled @!s; /*new |display_indent|*/ -pointer @!p; /*current node when calculating |pre_display_size|*/ -pointer @!q; /*glue specification when calculating |pre_display_size|*/ -internal_font_number @!f; /*font in current |char_node|*/ -int @!n; /*scope of paragraph shape specification*/ -scaled @!v; /*|w| plus possible glue amount*/ -scaled @!d; /*increment to |v|*/ -get_token(); /*|get_x_token| would fail on \.{\\ifmmode}\thinspace!*/ -if ((cur_cmd==math_shift)&&(mode > 0)) @<Go into display math mode@>@; -else{@+back_input();@<Go into ordinary math mode@>; - } -} - -@ @<Go into ordinary math mode@>= -{@+push_math(math_shift_group);eq_word_define(int_base+cur_fam_code,-1); -if (every_math!=null) begin_token_list(every_math, every_math_text); -} - -@ We get into ordinary math mode from display math mode when `\.{\\eqno}' or -`\.{\\leqno}' appears. In such cases |cur_chr| will be 0 or~1, respectively; -the value of |cur_chr| is placed onto |save_stack| for safe keeping. - -@<Cases of |main_control| that build...@>= -case mmode+eq_no: if (privileged()) - if (cur_group==math_shift_group) start_eq_no(); - else off_save();@+break; - -@ @<Put each...@>= -primitive("eqno", eq_no, 0); -@!@:eq\_no\_}{\.{\\eqno} primitive@> -primitive("leqno", eq_no, 1); -@!@:leq\_no\_}{\.{\\leqno} primitive@> - -@ When \TeX\ is in display math mode, |cur_group==math_shift_group|, -so it is not necessary for the |start_eq_no| procedure to test for -this condition. - -@<Declare act...@>= -static void start_eq_no(void) -{@+saved(0)=cur_chr;incr(save_ptr); -@<Go into ordinary math mode@>; -} - -@ @<Cases of |print_cmd_chr|...@>= -case eq_no: if (chr_code==1) print_esc("leqno");@+else print_esc("eqno");@+break; - -@ @<Forbidden...@>=non_math(eq_no): - -@ When we enter display math mode, we need to call |line_break| to -process the partial paragraph that has just been interrupted by the -display. Then we can set the proper values of |display_width| and -|display_indent| and |pre_display_size|. - -@<Go into display math mode@>= -{ if (head!=tail && !(type(tail)==whatsit_node && subtype(tail)==disp_node)) - { if (is_char_node(tail)) tail_append(new_penalty(inf_penalty))@; - else if (type(tail)!=glue_node) tail_append(new_penalty(inf_penalty))@; - else - {@+type(tail)=penalty_node;delete_glue_ref(glue_ptr(tail)); - flush_node_list(leader_ptr(tail));penalty(tail)=inf_penalty; - } - tail_append(new_param_glue(par_fill_skip_code)); - } -push_math(math_shift_group);mode=mmode; -eq_word_define(int_base+cur_fam_code,-1);@/ -if (every_display!=null) begin_token_list(every_display, every_display_text); -} - -@ @<Calculate the natural width, |w|, by which...@>= -v=shift_amount(just_box)+2*quad(cur_font);w=-max_dimen; -p=list_ptr(just_box); -while (p!=null) - {@+@<Let |d| be the natural width of node |p|; if the node is ``visible,'' |goto -found|; if the node is glue that stretches or shrinks, set |v:=max_dimen|@>; - if (v < max_dimen) v=v+d; - goto not_found; - found: if (v < max_dimen) - {@+v=v+d;w=v; - } - else{@+w=max_dimen;goto done; - } - not_found: p=link(p); - } -done: - -@ @<Let |d| be the natural width of node |p|...@>= -reswitch: if (is_char_node(p)) - {@+f=font(p);d=char_width(f, char_info(f, character(p))); - goto found; - } -switch (type(p)) { -case hlist_node: case vlist_node: case rule_node: {@+d=width(p);goto found; - } -case ligature_node: @<Make node |p| look like a |char_node|...@>@; -case kern_node: case math_node: d=width(p);@+break; -case glue_node: @<Let |d| be the natural width of this glue; if stretching or shrinking, -set |v:=max_dimen|; |goto found| in the case of leaders@>@;@+break; -case whatsit_node: @<Let |d| be the width of the whatsit |p|@>;@+break; -default:d=0; -} - -@ We need to be careful that |w|, |v|, and |d| do not depend on any |glue_set| -values, since such values are subject to system-dependent rounding. -System-dependent numbers are not allowed to infiltrate parameters like -|pre_display_size|, since \TeX82 is supposed to make the same decisions on all -machines. - -@<Let |d| be the natural width of this glue...@>= -{@+q=glue_ptr(p);d=width(q); -if (glue_sign(just_box)==stretching) - {@+if ((glue_order(just_box)==stretch_order(q))&&@| - (stretch(q)!=0)) - v=max_dimen; - } -else if (glue_sign(just_box)==shrinking) - {@+if ((glue_order(just_box)==shrink_order(q))&&@| - (shrink(q)!=0)) - v=max_dimen; - } -if (subtype(p) >= a_leaders) goto found; -} - -@ A displayed equation is considered to be three lines long, so we -calculate the length and offset of line number |prev_graf+2|. - -@<Calculate the length, |l|,...@>= -if (par_shape_ptr==null) - if ((hang_indent!=0)&&@| - (((hang_after >= 0)&&(prev_graf+2 > hang_after))||@| - (prev_graf+1 < -hang_after))) - {@+l=hsize-abs(hang_indent); - if (hang_indent > 0) s=hang_indent;@+else s=0; - } - else{@+l=hsize;s=0; - } -else{@+n=info(par_shape_ptr); - if (prev_graf+2 >= n) p=par_shape_ptr+2*n; - else p=par_shape_ptr+2*(prev_graf+2); - s=mem[p-1].sc;l=mem[p].sc; - } - -@ Subformulas of math formulas cause a new level of math mode to be entered, -on the semantic nest as well as the save stack. These subformulas arise in -several ways: (1)~A left brace by itself indicates the beginning of a -subformula that will be put into a box, thereby freezing its glue and -preventing line breaks. (2)~A subscript or superscript is treated as a -subformula if it is not a single character; the same applies to -the nucleus of things like \.{\\underline}. (3)~The \.{\\left} primitive -initiates a subformula that will be terminated by a matching \.{\\right}. -The group codes placed on |save_stack| in these three cases are -|math_group|, |math_group|, and |math_left_group|, respectively. - -Here is the code that handles case (1); the other cases are not quite as -trivial, so we shall consider them later. - -@<Cases of |main_control| that build...@>= -case mmode+left_brace: {@+tail_append(new_noad()); - back_input();scan_math(nucleus(tail)); - } @+break; - -@ Recall that the |nucleus|, |subscr|, and |supscr| fields in a noad are -broken down into subfields called |math_type| and either |info| or -|(fam, character)|. The job of |scan_math| is to figure out what to place -in one of these principal fields; it looks at the subformula that -comes next in the input, and places an encoding of that subformula -into a given word of |mem|. - -@d fam_in_range ((cur_fam >= 0)&&(cur_fam < 16)) - -@<Declare act...@>= -static void scan_math(pointer @!p) -{@+ -int c; /*math character code*/ -restart: @<Get the next non-blank non-relax...@>; -reswitch: switch (cur_cmd) { -case letter: case other_char: case char_given: {@+c=ho(math_code(cur_chr)); - if (c==0100000) - {@+@<Treat |cur_chr| as an active character@>; - goto restart; - } - } @+break; -case char_num: {@+scan_char_num();cur_chr=cur_val;cur_cmd=char_given; - goto reswitch; - } -case math_char_num: {@+scan_fifteen_bit_int();c=cur_val; - } @+break; -case math_given: c=cur_chr;@+break; -case delim_num: {@+scan_twenty_seven_bit_int();c=cur_val/010000; - } @+break; -default:@<Scan a subformula enclosed in braces and |return|@>@; -} @/ -math_type(p)=math_char;character(p)=qi(c%256); -if ((c >= var_code)&&fam_in_range) fam(p)=cur_fam; -else fam(p)=(c/256)%16; -} - -@ An active character that is an |outer_call| is allowed here. - -@<Treat |cur_chr|...@>= -{@+cur_cs=cur_chr+active_base; -cur_cmd=eq_type(cur_cs);cur_chr=equiv(cur_cs); -x_token();back_input(); -} - -@ The pointer |p| is placed on |save_stack| while a complex subformula -is being scanned. - -@<Scan a subformula...@>= -{@+back_input();scan_left_brace();@/ -saved(0)=p;incr(save_ptr);push_math(math_group);return; -} - -@ The simplest math formula is, of course, `\.{\${ }\$}', when no noads are -generated. The next simplest cases involve a single character, e.g., -`\.{\$x\$}'. Even though such cases may not seem to be very interesting, -the reader can perhaps understand how happy the author was when `\.{\$x\$}' -was first properly typeset by \TeX. The code in this section was used. -@^Knuth, Donald Ervin@> - -@<Cases of |main_control| that build...@>= -case mmode+letter: case mmode+other_char: case mmode+char_given: - set_math_char(ho(math_code(cur_chr)));@+break; -case mmode+char_num: {@+scan_char_num();cur_chr=cur_val; - set_math_char(ho(math_code(cur_chr))); - } @+break; -case mmode+math_char_num: {@+scan_fifteen_bit_int();set_math_char(cur_val); - } @+break; -case mmode+math_given: set_math_char(cur_chr);@+break; -case mmode+delim_num: {@+scan_twenty_seven_bit_int(); - set_math_char(cur_val/010000); - } @+break; - -@ The |set_math_char| procedure creates a new noad appropriate to a given -math code, and appends it to the current mlist. However, if the math code -is sufficiently large, the |cur_chr| is treated as an active character and -nothing is appended. - -@<Declare act...@>= -static void set_math_char(int @!c) -{@+pointer p; /*the new noad*/ -if (c >= 0100000) - @<Treat |cur_chr|...@>@; -else{@+p=new_noad();math_type(nucleus(p))=math_char; - character(nucleus(p))=qi(c%256); - fam(nucleus(p))=(c/256)%16; - if (c >= var_code) - {@+if (fam_in_range) fam(nucleus(p))=cur_fam; - type(p)=ord_noad; - } - else type(p)=ord_noad+(c/010000); - link(tail)=p;tail=p; - } -} - -@ Primitive math operators like \.{\\mathop} and \.{\\underline} are given -the command code |math_comp|, supplemented by the noad type that they -generate. - -@<Put each...@>= -primitive("mathord", math_comp, ord_noad); -@!@:math\_ord\_}{\.{\\mathord} primitive@> -primitive("mathop", math_comp, op_noad); -@!@:math\_op\_}{\.{\\mathop} primitive@> -primitive("mathbin", math_comp, bin_noad); -@!@:math\_bin\_}{\.{\\mathbin} primitive@> -primitive("mathrel", math_comp, rel_noad); -@!@:math\_rel\_}{\.{\\mathrel} primitive@> -primitive("mathopen", math_comp, open_noad); -@!@:math\_open\_}{\.{\\mathopen} primitive@> -primitive("mathclose", math_comp, close_noad); -@!@:math\_close\_}{\.{\\mathclose} primitive@> -primitive("mathpunct", math_comp, punct_noad); -@!@:math\_punct\_}{\.{\\mathpunct} primitive@> -primitive("mathinner", math_comp, inner_noad); -@!@:math\_inner\_}{\.{\\mathinner} primitive@> -primitive("underline", math_comp, under_noad); -@!@:underline\_}{\.{\\underline} primitive@> -primitive("overline", math_comp, over_noad);@/ -@!@:overline\_}{\.{\\overline} primitive@> -primitive("displaylimits", limit_switch, normal); -@!@:display\_limits\_}{\.{\\displaylimits} primitive@> -primitive("limits", limit_switch, limits); -@!@:limits\_}{\.{\\limits} primitive@> -primitive("nolimits", limit_switch, no_limits); -@!@:no\_limits\_}{\.{\\nolimits} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case math_comp: switch (chr_code) { - case ord_noad: print_esc("mathord");@+break; - case op_noad: print_esc("mathop");@+break; - case bin_noad: print_esc("mathbin");@+break; - case rel_noad: print_esc("mathrel");@+break; - case open_noad: print_esc("mathopen");@+break; - case close_noad: print_esc("mathclose");@+break; - case punct_noad: print_esc("mathpunct");@+break; - case inner_noad: print_esc("mathinner");@+break; - case under_noad: print_esc("underline");@+break; - default:print_esc("overline"); - } @+break; -case limit_switch: if (chr_code==limits) print_esc("limits"); - else if (chr_code==no_limits) print_esc("nolimits"); - else print_esc("displaylimits");@+break; - -@ @<Cases of |main_control| that build...@>= -case mmode+math_comp: {@+tail_append(new_noad()); - type(tail)=cur_chr;scan_math(nucleus(tail)); - } @+break; -case mmode+limit_switch: math_limit_switch();@+break; - -@ @<Declare act...@>= -static void math_limit_switch(void) -{@+ -if (head!=tail) if (type(tail)==op_noad) - {@+subtype(tail)=cur_chr;return; - } -print_err("Limit controls must follow a math operator"); -@.Limit controls must follow...@> -help1("I'm ignoring this misplaced \\limits or \\nolimits command.");error(); -} - -@ Delimiter fields of noads are filled in by the |scan_delimiter| routine. -The first parameter of this procedure is the |mem| address where the -delimiter is to be placed; the second tells if this delimiter follows -\.{\\radical} or not. - -@<Declare act...@>= -static void scan_delimiter(pointer @!p, bool @!r) -{@+if (r) scan_twenty_seven_bit_int(); -else{@+@<Get the next non-blank non-relax...@>; - switch (cur_cmd) { - case letter: case other_char: cur_val=del_code(cur_chr);@+break; - case delim_num: scan_twenty_seven_bit_int();@+break; - default:cur_val=-1; - } - } -if (cur_val < 0) @<Report that an invalid delimiter code is being changed to null; -set~|cur_val:=0|@>; -small_fam(p)=(cur_val/04000000)%16; -small_char(p)=qi((cur_val/010000)%256); -large_fam(p)=(cur_val/256)%16; -large_char(p)=qi(cur_val%256); -} - -@ @<Report that an invalid delimiter...@>= -{@+print_err("Missing delimiter (. inserted)"); -@.Missing delimiter...@> -help6("I was expecting to see something like `(' or `\\{' or",@/ - "`\\}' here. If you typed, e.g., `{' instead of `\\{', you",@/ - "should probably delete the `{' by typing `1' now, so that",@/ - "braces don't get unbalanced. Otherwise just proceed.",@/ - "Acceptable delimiters are characters whose \\delcode is",@/ - "nonnegative, or you can use `\\delimiter <delimiter code>'."); -back_error();cur_val=0; -} - -@ @<Cases of |main_control| that build...@>= -case mmode+radical: math_radical();@+break; - -@ @<Declare act...@>= -static void math_radical(void) -{@+tail_append(get_node(radical_noad_size)); -type(tail)=radical_noad;subtype(tail)=normal; -mem[nucleus(tail)].hh=empty_field; -mem[subscr(tail)].hh=empty_field; -mem[supscr(tail)].hh=empty_field; -scan_delimiter(left_delimiter(tail), true);scan_math(nucleus(tail)); -} - -@ @<Cases of |main_control| that build...@>= -case mmode+accent: case mmode+math_accent: math_ac();@+break; - -@ @<Declare act...@>= -static void math_ac(void) -{@+if (cur_cmd==accent) - @<Complain that the user should have said \.{\\mathaccent}@>; -tail_append(get_node(accent_noad_size)); -type(tail)=accent_noad;subtype(tail)=normal; -mem[nucleus(tail)].hh=empty_field; -mem[subscr(tail)].hh=empty_field; -mem[supscr(tail)].hh=empty_field; -math_type(accent_chr(tail))=math_char; -scan_fifteen_bit_int(); -character(accent_chr(tail))=qi(cur_val%256); -if ((cur_val >= var_code)&&fam_in_range) fam(accent_chr(tail))=cur_fam; -else fam(accent_chr(tail))=(cur_val/256)%16; -scan_math(nucleus(tail)); -} - -@ @<Complain that the user should have said \.{\\mathaccent}@>= -{@+print_err("Please use ");print_esc("mathaccent"); -print(" for accents in math mode"); -@.Please use \\mathaccent...@> -help2("I'm changing \\accent to \\mathaccent here; wish me luck.",@/ - "(Accents are not the same in formulas as they are in text.)"); -error(); -} - -@ @<Cases of |main_control| that build...@>= -case mmode+vcenter: {@+scan_spec(vcenter_group, false);normal_paragraph(); - push_nest();mode=-vmode;prev_depth=ignore_depth; - if (every_vbox!=null) begin_token_list(every_vbox, every_vbox_text); - } @+break; - -@ @<Cases of |handle...@>= -case vcenter_group: {@+end_graf();unsave();save_ptr=save_ptr-2; - p=vpack(link(head), saved(1), saved_hfactor(1), saved_vfactor(1), saved(0));pop_nest(); - tail_append(new_noad());type(tail)=vcenter_noad; - math_type(nucleus(tail))=sub_box;info(nucleus(tail))=p; - } @+break; - -@ The routine that inserts a |style_node| holds no surprises. - -@<Put each...@>= -primitive("displaystyle", math_style, display_style); -@!@:display\_style\_}{\.{\\displaystyle} primitive@> -primitive("textstyle", math_style, text_style); -@!@:text\_style\_}{\.{\\textstyle} primitive@> -primitive("scriptstyle", math_style, script_style); -@!@:script\_style\_}{\.{\\scriptstyle} primitive@> -primitive("scriptscriptstyle", math_style, script_script_style); -@!@:script\_script\_style\_}{\.{\\scriptscriptstyle} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case math_style: print_style(chr_code);@+break; - -@ @<Cases of |main_control| that build...@>= -case mmode+math_style: tail_append(new_style(cur_chr))@;@+break; -case mmode+non_script: {@+tail_append(new_glue(zero_glue)); - subtype(tail)=cond_math_glue; - } @+break; -case mmode+math_choice: append_choices();@+break; - -@ The routine that scans the four mlists of a \.{\\mathchoice} is very -much like the routine that builds discretionary nodes. - -@<Declare act...@>= -static void append_choices(void) -{@+tail_append(new_choice());incr(save_ptr);saved(-1)=0; -push_math(math_choice_group);scan_left_brace(); -} - -@ @<Cases of |handle_right_brace|...@>= -case math_choice_group: build_choices();@+break; - -@ @<Declare act...@>= -@t\4@>@<Declare the function called |fin_mlist|@>@t@>@;@/ -static void build_choices(void) -{@+ -pointer p; /*the current mlist*/ -unsave();p=fin_mlist(null); -switch (saved(-1)) { -case 0: display_mlist(tail)=p;@+break; -case 1: text_mlist(tail)=p;@+break; -case 2: script_mlist(tail)=p;@+break; -case 3: {@+script_script_mlist(tail)=p;decr(save_ptr);return; - } -} /*there are no other cases*/ -incr(saved(-1));push_math(math_choice_group);scan_left_brace(); -} - -@ Subscripts and superscripts are attached to the previous nucleus by the -@^superscripts@>@^subscripts@> -action procedure called |sub_sup|. We use the facts that |sub_mark==sup_mark+1| -and |subscr(p)==supscr(p)+1|. - -@<Cases of |main_control| that build...@>= -case mmode+sub_mark: case mmode+sup_mark: sub_sup();@+break; - -@ @<Declare act...@>= -static void sub_sup(void) -{@+small_number t; /*type of previous sub/superscript*/ -pointer @!p; /*field to be filled by |scan_math|*/ -t=empty;p=null; -if (tail!=head) if (scripts_allowed(tail)) - {@+p=supscr(tail)+cur_cmd-sup_mark; /*|supscr| or |subscr|*/ - t=math_type(p); - } -if ((p==null)||(t!=empty)) @<Insert a dummy noad to be sub/superscripted@>; -scan_math(p); -} - -@ @<Insert a dummy...@>= -{@+tail_append(new_noad()); -p=supscr(tail)+cur_cmd-sup_mark; /*|supscr| or |subscr|*/ -if (t!=empty) - {@+if (cur_cmd==sup_mark) - {@+print_err("Double superscript"); -@.Double superscript@> - help1("I treat `x^1^2' essentially like `x^1{}^2'."); - } - else{@+print_err("Double subscript"); -@.Double subscript@> - help1("I treat `x_1_2' essentially like `x_1{}_2'."); - } - error(); - } -} - -@ An operation like `\.{\\over}' causes the current mlist to go into a -state of suspended animation: |incompleat_noad| points to a |fraction_noad| -that contains the mlist-so-far as its numerator, while the denominator -is yet to come. Finally when the mlist is finished, the denominator will -go into the incompleat fraction noad, and that noad will become the -whole formula, unless it is surrounded by `\.{\\left}' and `\.{\\right}' -delimiters. - -@d above_code 0 /* `\.{\\above}' */ -@d over_code 1 /* `\.{\\over}' */ -@d atop_code 2 /* `\.{\\atop}' */ -@d delimited_code 3 /* `\.{\\abovewithdelims}', etc.*/ - -@<Put each...@>= -primitive("above", above, above_code);@/ -@!@:above\_}{\.{\\above} primitive@> -primitive("over", above, over_code);@/ -@!@:over\_}{\.{\\over} primitive@> -primitive("atop", above, atop_code);@/ -@!@:atop\_}{\.{\\atop} primitive@> -primitive("abovewithdelims", above, delimited_code+above_code);@/ -@!@:above\_with\_delims\_}{\.{\\abovewithdelims} primitive@> -primitive("overwithdelims", above, delimited_code+over_code);@/ -@!@:over\_with\_delims\_}{\.{\\overwithdelims} primitive@> -primitive("atopwithdelims", above, delimited_code+atop_code); -@!@:atop\_with\_delims\_}{\.{\\atopwithdelims} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case above: switch (chr_code) { - case over_code: print_esc("over");@+break; - case atop_code: print_esc("atop");@+break; - case delimited_code+above_code: print_esc("abovewithdelims");@+break; - case delimited_code+over_code: print_esc("overwithdelims");@+break; - case delimited_code+atop_code: print_esc("atopwithdelims");@+break; - default:print_esc("above"); - } @+break; - -@ @<Cases of |main_control| that build...@>= -case mmode+above: math_fraction();@+break; - -@ @<Declare act...@>= -static void math_fraction(void) -{@+small_number c; /*the type of generalized fraction we are scanning*/ -c=cur_chr; -if (incompleat_noad!=null) - @<Ignore the fraction operation and complain about this ambiguous case@>@; -else{@+incompleat_noad=get_node(fraction_noad_size); - type(incompleat_noad)=fraction_noad; - subtype(incompleat_noad)=normal; - math_type(numerator(incompleat_noad))=sub_mlist; - info(numerator(incompleat_noad))=link(head); - mem[denominator(incompleat_noad)].hh=empty_field; - mem[left_delimiter(incompleat_noad)].qqqq=null_delimiter; - mem[right_delimiter(incompleat_noad)].qqqq=null_delimiter;@/ - link(head)=null;tail=head; - @<Use code |c| to distinguish between generalized fractions@>; - } -} - -@ @<Use code |c|...@>= -if (c >= delimited_code) - {@+scan_delimiter(left_delimiter(incompleat_noad), false); - scan_delimiter(right_delimiter(incompleat_noad), false); - } -switch (c%delimited_code) { -case above_code: {@+scan_normal_dimen; - thickness(incompleat_noad)=cur_val; - } @+break; -case over_code: thickness(incompleat_noad)=default_code;@+break; -case atop_code: thickness(incompleat_noad)=0; -} /*there are no other cases*/ - -@ @<Ignore the fraction...@>= -{@+if (c >= delimited_code) - {@+scan_delimiter(garbage, false);scan_delimiter(garbage, false); - } -if (c%delimited_code==above_code) scan_normal_dimen; -print_err("Ambiguous; you need another { and }"); -@.Ambiguous...@> -help3("I'm ignoring this fraction specification, since I don't",@/ - "know whether a construction like `x \\over y \\over z'",@/ - "means `{x \\over y} \\over z' or `x \\over {y \\over z}'."); -error(); -} - -@ At the end of a math formula or subformula, the |fin_mlist| routine is -called upon to return a pointer to the newly completed mlist, and to -pop the nest back to the enclosing semantic level. The parameter to -|fin_mlist|, if not null, points to a |right_noad| that ends the -current mlist; this |right_noad| has not yet been appended. - -@<Declare the function called |fin_mlist|@>= -static pointer fin_mlist(pointer @!p) -{@+pointer q; /*the mlist to return*/ -if (incompleat_noad!=null) @<Compleat the incompleat noad@>@; -else{@+link(tail)=p;q=link(head); - } -pop_nest();return q; -} - -@ @<Compleat...@>= -{@+math_type(denominator(incompleat_noad))=sub_mlist; -info(denominator(incompleat_noad))=link(head); -if (p==null) q=incompleat_noad; -else{@+q=info(numerator(incompleat_noad)); - if ((type(q)!=left_noad)||(delim_ptr==null)) confusion("right"); -@:this can't happen right}{\quad right@> - info(numerator(incompleat_noad))=link(delim_ptr); - link(delim_ptr)=incompleat_noad;link(incompleat_noad)=p; - } -} - -@ Now at last we're ready to see what happens when a right brace occurs -in a math formula. Two special cases are simplified here: Braces are effectively -removed when they surround a single Ord without sub/superscripts, or when they -surround an accent that is the nucleus of an Ord atom. - -@<Cases of |handle...@>= -case math_group: {@+unsave();decr(save_ptr);@/ - math_type(saved(0))=sub_mlist;p=fin_mlist(null);info(saved(0))=p; - if (p!=null) if (link(p)==null) - if (type(p)==ord_noad) - {@+if (math_type(subscr(p))==empty) - if (math_type(supscr(p))==empty) - {@+mem[saved(0)].hh=mem[nucleus(p)].hh; - free_node(p, noad_size); - } - } - else if (type(p)==accent_noad) if (saved(0)==nucleus(tail)) - if (type(tail)==ord_noad) @<Replace the tail of the list by |p|@>; - } @+break; - -@ @<Replace the tail...@>= -{@+q=head;while (link(q)!=tail) q=link(q); -link(q)=p;free_node(tail, noad_size);tail=p; -} - -@ We have dealt with all constructions of math mode except `\.{\\left}' and -`\.{\\right}', so the picture is completed by the following sections of -the program. - -@<Put each...@>= -primitive("left", left_right, left_noad); -@!@:left\_}{\.{\\left} primitive@> -primitive("right", left_right, right_noad); -@!@:right\_}{\.{\\right} primitive@> -text(frozen_right)=text(cur_val);eqtb[frozen_right]=eqtb[cur_val]; - -@ @<Cases of |print_cmd_chr|...@>= -case left_right: if (chr_code==left_noad) print_esc("left") -@/@<Cases of |left_right| for |print_cmd_chr|@>;@/ -else print_esc("right");@+break; - -@ @<Cases of |main_control| that build...@>= -case mmode+left_right: math_left_right();@+break; - -@ @<Declare act...@>= -static void math_left_right(void) -{@+small_number t; /*|left_noad| or |right_noad|*/ -pointer @!p; /*new noad*/ -pointer @!q; /*resulting mlist*/ -t=cur_chr; -if ((t!=left_noad)&&(cur_group!=math_left_group)) - @<Try to recover from mismatched \.{\\right}@>@; -else{@+p=new_noad();type(p)=t; - scan_delimiter(delimiter(p), false); - if (t==middle_noad) - {@+type(p)=right_noad;subtype(p)=middle_noad; - } - if (t==left_noad) q=p; - else{@+q=fin_mlist(p);unsave(); /*end of |math_left_group|*/ - } - if (t!=right_noad) - {@+push_math(math_left_group);link(head)=q;tail=p; - delim_ptr=p; - } - else{@+ - tail_append(new_noad());type(tail)=inner_noad; - math_type(nucleus(tail))=sub_mlist; - info(nucleus(tail))=q; - } - } -} - -@ @<Try to recover from mismatch...@>= -{@+if (cur_group==math_shift_group) - {@+scan_delimiter(garbage, false); - print_err("Extra "); - if (t==middle_noad) - {@+print_esc("middle"); -@.Extra \\middle.@> - help1("I'm ignoring a \\middle that had no matching \\left."); - } - else{@+print_esc("right"); -@.Extra \\right.@> - help1("I'm ignoring a \\right that had no matching \\left."); - } - error(); - } -else off_save(); -} - -@ Here is the only way out of math mode. - -@<Cases of |main_control| that build...@>= -case mmode+math_shift: if (cur_group==math_shift_group) after_math(); - else off_save();@+break; - -@ @<Declare act...@>= -static void after_math(void) -{@+bool l; /*`\.{\\leqno}' instead of `\.{\\eqno}'*/ -bool @!danger; /*not enough symbol fonts are present*/ -int @!m; /*|mmode| or |-mmode|*/ -pointer @!p; /*the formula*/ -pointer @!a; /*box containing equation number*/ -danger=false; -@<Check that the necessary fonts for math symbols are present; if not, flush the current -math lists and set |danger:=true|@>; -m=mode;l=false;p=fin_mlist(null); /*this pops the nest*/ -if (mode==-m) /*end of equation number*/ - {@+@<Check that another \.\$ follows@>; - cur_mlist=p;cur_style=text_style;mlist_penalties=false; - mlist_to_hlist();a=hpack(link(temp_head), natural); - unsave();decr(save_ptr); /*now |cur_group==math_shift_group|*/ - if (saved(0)==1) l=true; - danger=false; - @<Check that the necessary fonts for math symbols are present; if not, flush the -current math lists and set |danger:=true|@>; - m=mode;p=fin_mlist(null); - } -else a=null; -if (m < 0) @<Finish math in text@>@; -else{@+if (a==null) @<Check that another \.\$ follows@>; - @<Finish displayed math@>; - } -} - -@ @<Check that the necessary fonts...@>= -if ((font_params[fam_fnt(2+text_size)] < total_mathsy_params)||@| - (font_params[fam_fnt(2+script_size)] < total_mathsy_params)||@| - (font_params[fam_fnt(2+script_script_size)] < total_mathsy_params)) - {@+print_err("Math formula deleted: Insufficient symbol fonts");@/ -@.Math formula deleted...@> - help3("Sorry, but I can't typeset math unless \\textfont 2",@/ - "and \\scriptfont 2 and \\scriptscriptfont 2 have all",@/ - "the \\fontdimen values needed in math symbol fonts."); - error();flush_math();danger=true; - } -else if ((font_params[fam_fnt(3+text_size)] < total_mathex_params)||@| - (font_params[fam_fnt(3+script_size)] < total_mathex_params)||@| - (font_params[fam_fnt(3+script_script_size)] < total_mathex_params)) - {@+print_err("Math formula deleted: Insufficient extension fonts");@/ - help3("Sorry, but I can't typeset math unless \\textfont 3",@/ - "and \\scriptfont 3 and \\scriptscriptfont 3 have all",@/ - "the \\fontdimen values needed in math extension fonts."); - error();flush_math();danger=true; - } - -@ The |unsave| is done after everything else here; hence an appearance of -`\.{\\mathsurround}' inside of `\.{\$...\$}' affects the spacing at these -particular \.\$'s. This is consistent with the conventions of -`\.{\$\$...\$\$}', since `\.{\\abovedisplayskip}' inside a display affects the -space above that display. - -@<Finish math in text@>= -{@+tail_append(new_math(math_surround, before)); -cur_mlist=p;cur_style=text_style;mlist_penalties=(mode > 0);mlist_to_hlist(); -link(tail)=link(temp_head); -while (link(tail)!=null) tail=link(tail); -tail_append(new_math(math_surround, after)); -space_factor=1000;unsave(); -} - -@ \TeX\ gets to the following part of the program when the first `\.\$' ending -a display has been scanned. - -@<Check that another \.\$ follows@>= -{@+get_x_token(); -if (cur_cmd!=math_shift) - {@+print_err("Display math should end with $$"); -@.Display math...with \$\$@> - help2("The `$' that I just saw supposedly matches a previous `$$'.",@/ - "So I shall assume that you typed `$$' both times."); - back_error(); - } -} - -@ We have saved the worst for last: The fussiest part of math mode processing -occurs when a displayed formula is being centered and placed with an optional -equation number. - -@<Local variables for finishing...@>= -pointer @!b; /*box containing the equation*/ -scaled @!w; /*width of the equation*/ -scaled @!z; /*width of the line*/ -scaled @!e; /*width of equation number*/ -scaled @!q; /*width of equation number plus space to separate from equation*/ -scaled @!d; /*displacement of equation in the line*/ -scaled @!s; /*move the line right this much*/ -small_number @!g1, @!g2; /*glue parameter codes for before and after*/ -pointer @!r; /*kern node used to position the display*/ -pointer @!t; /*tail of adjustment list*/ - -@ At this time |p| points to the mlist for the formula; |a| is either -|null| or it points to a box containing the equation number; and we are in -vertical mode (or internal vertical mode). - -@<Finish displayed math@>= -cur_mlist=p;cur_style=display_style;mlist_penalties=false; -mlist_to_hlist();p=link(temp_head); link(temp_head)=null;@/ -{@+ pointer q; - q=new_disp_node(); - if (!danger) { display_formula(q)=p; display_eqno(q)=a; display_left(q)=l; } - /* adding parameter nodes */ - if (hang_indent!=0) - { add_par_node(dimen_type,hang_indent_code,hang_indent); - if (hang_after!=1) - add_par_node(int_type,hang_after_code,hang_after); - } - add_par_node(dimen_type,line_skip_limit_code,line_skip_limit); - add_par_node(glue_type,line_skip_code,line_skip); - add_par_node(glue_type,baseline_skip_code,baseline_skip); - display_params(q)=link(temp_head); link(temp_head)=null; - display_no_bs(q)= prev_depth <= ignore_depth; - tail_append(q); -} -/* this is from |resume_after_display| */ -if (cur_group!=math_shift_group) confusion("display"); -@:this can't happen display}{\quad display@> -unsave(); -mode=hmode;space_factor=1000;set_cur_lang;clang=cur_lang; -prev_graf=(norm_min(left_hyphen_min)*0100+norm_min(right_hyphen_min)) - *0200000+cur_lang; -@<Scan an optional space@>; - -@ @<Declare act...@>= -static void resume_after_display(void) -{@+if (cur_group!=math_shift_group) confusion("display"); -@:this can't happen display}{\quad display@> -unsave();prev_graf=prev_graf+3; -push_nest();mode=hmode;space_factor=1000;set_cur_lang;clang=cur_lang; -prev_graf=(norm_min(left_hyphen_min)*0100+norm_min(right_hyphen_min)) - *0200000+cur_lang; -@<Scan an optional space@>; -if (nest_ptr==1) build_page(); -} - -@ The user can force the equation number to go on a separate line -by causing its width to be zero. - -@<Squeeze the equation as much as possible...@>= -{@+if ((e!=0)&&((w-total_shrink[normal]+q <= z)||@| - (total_shrink[fil]!=0)||(total_shrink[fill]!=0)|| - (total_shrink[filll]!=0))) - {@+list_ptr(b)=null;flush_node_list(b); - b=hpack(p, z-q, 0, 0, exactly); - } -else{@+e=0; - if (w > z) - {@+list_ptr(b)=null;flush_node_list(b); - b=hpack(p, z, 0, 0, exactly); - } - } -w=width(b); -} - -@ We try first to center the display without regard to the existence of -the equation number. If that would make it too close (where ``too close'' -means that the space between display and equation number is less than the -width of the equation number), we either center it in the remaining space -or move it as far from the equation number as possible. The latter alternative -is taken only if the display begins with glue, since we assume that the -user put glue there to control the spacing precisely. - -@<Determine the displacement, |d|, of the left edge of the equation...@>= -d=half(z-w); -if ((e > 0)&&(d < 2*e)) /*too close*/ - {@+d=half(z-w-e); - if (p!=null) if (!is_char_node(p)) if (type(p)==glue_node) d=0; - } - -@ If the equation number is set on a line by itself, either before or -after the formula, we append an infinite penalty so that no page break will -separate the display from its number; and we use the same size and -displacement for all three potential lines of the display, even though -`\.{\\parshape}' may specify them differently. - -@<Append the glue or equation number preceding the display@>= -tail_append(new_penalty(pre_display_penalty));@/ -if ((d+s <= pre_display_size)||l) /*not enough clearance*/ - {@+g1=above_display_skip_code;g2=below_display_skip_code; - } -else{@+g1=above_display_short_skip_code; - g2=below_display_short_skip_code; - } -if (l&&(e==0)) /*it follows that |type(a)==hlist_node|*/ - {@+shift_amount(a)=s;append_to_vlist(a); - tail_append(new_penalty(inf_penalty)); - } -else tail_append(new_param_glue(g1)) - -@ @<Append the display and perhaps also the equation number@>= -if (e!=0) - {@+r=new_kern(z-w-e-d); - if (l) - {@+link(a)=r;link(r)=b;b=a;d=0; - } - else{@+link(b)=r;link(r)=a; - } - b=hpack(b, natural); - } -shift_amount(b)=s+d;append_to_vlist(b) - -@ @<Append the glue or equation number following the display@>= -if ((a!=null)&&(e==0)&&!l) - {@+tail_append(new_penalty(inf_penalty)); - shift_amount(a)=s+z-width(a); - append_to_vlist(a); - g2=0; - } -if (t!=adjust_head) /*migrating material comes after equation number*/ - {@+link(tail)=link(adjust_head);tail=t; - } -tail_append(new_penalty(post_display_penalty)); -if (g2 > 0) tail_append(new_param_glue(g2)) - -@ When \.{\\halign} appears in a display, the alignment routines operate -essentially as they do in vertical mode. Then the following program is -activated, with |p| and |q| pointing to the beginning and end of the -resulting list, and with |aux_save| holding the |prev_depth| value. - -@<Finish an alignment in a display@>= -{@+do_assignments(); -if (cur_cmd!=math_shift) @<Pontificate about improper alignment in display@>@; -else@<Check that another \.\$ follows@>; -pop_nest(); -tail_append(new_penalty(pre_display_penalty)); -tail_append(new_param_glue(above_display_skip_code)); -link(tail)=p; -if (p!=null) tail=q; -tail_append(new_penalty(post_display_penalty)); -tail_append(new_param_glue(below_display_skip_code)); -prev_depth=aux_save.sc;resume_after_display(); -} - -@ @<Pontificate...@>= -{@+print_err("Missing $$ inserted"); -@.Missing {\$\$} inserted@> -help2("Displays can use special alignments (like \\eqalignno)",@/ - "only if nothing but the alignment itself is between $$'s."); -back_error(); -} - -@* Mode-independent processing. -The long |main_control| procedure has now been fully specified, except for -certain activities that are independent of the current mode. These activities -do not change the current vlist or hlist or mlist; if they change anything, -it is the value of a parameter or the meaning of a control sequence. - -Assignments to values in |eqtb| can be global or local. Furthermore, a -control sequence can be defined to be `\.{\\long}', `\.{\\protected}', -or `\.{\\outer}', and it might or might not be expanded. The prefixes -`\.{\\global}', `\.{\\long}', `\.{\\protected}', -and `\.{\\outer}' can occur in any order. Therefore we assign binary numeric -codes, making it possible to accumulate the union of all specified prefixes -by adding the corresponding codes. (\PASCAL's |set| operations could also -have been used.) - -@<Put each...@>= -primitive("long", prefix, 1); -@!@:long\_}{\.{\\long} primitive@> -primitive("outer", prefix, 2); -@!@:outer\_}{\.{\\outer} primitive@> -primitive("global", prefix, 4); -@!@:global\_}{\.{\\global} primitive@> -primitive("def", def, 0); -@!@:def\_}{\.{\\def} primitive@> -primitive("gdef", def, 1); -@!@:gdef\_}{\.{\\gdef} primitive@> -primitive("edef", def, 2); -@!@:edef\_}{\.{\\edef} primitive@> -primitive("xdef", def, 3); -@!@:xdef\_}{\.{\\xdef} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case prefix: if (chr_code==1) print_esc("long"); - else if (chr_code==2) print_esc("outer") - @/@<Cases of |prefix| for |print_cmd_chr|@>;@/ - else print_esc("global");@+break; -case def: if (chr_code==0) print_esc("def"); - else if (chr_code==1) print_esc("gdef"); - else if (chr_code==2) print_esc("edef"); - else print_esc("xdef");@+break; - -@ Every prefix, and every command code that might or might not be prefixed, -calls the action procedure |prefixed_command|. This routine accumulates -a sequence of prefixes until coming to a non-prefix, then it carries out -the command. - -@<Cases of |main_control| that don't...@>= -any_mode(toks_register): -any_mode(assign_toks): -any_mode(assign_int): -any_mode(assign_dimen): -any_mode(assign_glue): -any_mode(assign_mu_glue): -any_mode(assign_font_dimen): -any_mode(assign_font_int): -any_mode(set_aux): -any_mode(set_prev_graf): -any_mode(set_page_dimen): -any_mode(set_page_int): -any_mode(set_box_dimen): -any_mode(set_shape): -any_mode(def_code): -any_mode(def_family): -any_mode(set_font): -any_mode(def_font): -any_mode(internal_register): -any_mode(advance): -any_mode(multiply): -any_mode(divide): -any_mode(prefix): -any_mode(let): -any_mode(shorthand_def): -any_mode(read_to_cs): -any_mode(def): -any_mode(set_box): -any_mode(hyph_data): -any_mode(set_interaction): prefixed_command();@+break; - -@ If the user says, e.g., `\.{\\global\\global}', the redundancy is -silently accepted. - -@<Declare act...@>= -@t\4@>@<Declare subprocedures for |prefixed_command|@>@t@>@;@/ -static void prefixed_command(void) -{@+ -small_number a; /*accumulated prefix codes so far*/ -internal_font_number @!f; /*identifies a font*/ -int @!j; /*index into a \.{\\parshape} specification*/ -font_index @!k; /*index into |font_info|*/ -pointer @!p, @!q; /*for temporary short-term use*/ -int @!n; /*ditto*/ -bool @!e; /*should a definition be expanded? or was \.{\\let} not done?*/ -a=0; -while (cur_cmd==prefix) - {@+if (!odd(a/cur_chr)) a=a+cur_chr; - @<Get the next non-blank non-relax...@>; - if (cur_cmd <= max_non_prefixed_command) - @<Discard erroneous prefixes and |return|@>; - if (tracing_commands > 2) if (eTeX_ex) show_cur_cmd_chr(); - } -@<Discard the prefixes \.{\\long} and \.{\\outer} if they are irrelevant@>; -@<Adjust \(f)for the setting of \.{\\globaldefs}@>; -switch (cur_cmd) { -@t\4@>@<Assignments@>@; -default:confusion("prefix"); -@:this can't happen prefix}{\quad prefix@> -} -done: @<Insert a token saved by \.{\\afterassignment}, if any@>; -} - -@ @<Discard erroneous...@>= -{@+print_err("You can't use a prefix with `"); -@.You can't use a prefix with x@> -print_cmd_chr(cur_cmd, cur_chr);print_char('\''); -help1("I'll pretend you didn't say \\long or \\outer or \\global."); -if (eTeX_ex) help_line[0]=@| - "I'll pretend you didn't say \\long or \\outer or \\global or \\protected."; -back_error();return; -} - -@ @<Discard the prefixes...@>= -if (a >= 8) - {@+j=protected_token;a=a-8; - } -else j=0; -if ((cur_cmd!=def)&&((a%4!=0)||(j!=0))) - {@+print_err("You can't use `");print_esc("long");print("' or `"); - print_esc("outer"); - help1("I'll pretend you didn't say \\long or \\outer here."); - if (eTeX_ex) - {@+help_line[0]=@| - "I'll pretend you didn't say \\long or \\outer or \\protected here."; - print("' or `");print_esc("protected"); - } - print("' with `"); -@.You can't use \\long...@> - print_cmd_chr(cur_cmd, cur_chr);print_char('\''); - error(); - } - -@ The previous routine does not have to adjust |a| so that |a%4==0|, -since the following routines test for the \.{\\global} prefix as follows. - -@d global (a >= 4) -@d define(A, B, C) if (global) geq_define(A, B, C);@+else eq_define(A, B, C) -@d word_define(A, B) if (global) geq_word_define(A, B);@+else eq_word_define(A, B) - -@<Adjust \(f)for the setting of \.{\\globaldefs}@>= -if (global_defs!=0) - if (global_defs < 0) - {@+if (global) a=a-4; - } - else{@+if (!global) a=a+4; - } - -@ When a control sequence is to be defined, by \.{\\def} or \.{\\let} or -something similar, the |get_r_token| routine will substitute a special -control sequence for a token that is not redefinable. - -@<Declare subprocedures for |prefixed_command|@>= -static void get_r_token(void) -{@+ -restart: @/do@+{get_token(); -}@+ while (!(cur_tok!=space_token)); -if ((cur_cs==0)||(cur_cs > frozen_control_sequence)) - {@+print_err("Missing control sequence inserted"); -@.Missing control...@> - help5("Please don't say `\\def cs{...}', say `\\def\\cs{...}'.",@/ - "I've inserted an inaccessible control sequence so that your",@/ - "definition will be completed without mixing me up too badly.",@/ - "You can recover graciously from this error, if you're",@/ - "careful; see exercise 27.2 in The TeXbook."); -@:TeXbook}{\sl The \TeX book@> - if (cur_cs==0) back_input(); - cur_tok=cs_token_flag+frozen_protection;ins_error();goto restart; - } -} - -@ @<Initialize table entries...@>= -text(frozen_protection)=s_no("inaccessible"); -@.inaccessible@> - -@ Here's an example of the way many of the following routines operate. -(Unfortunately, they aren't all as simple as this.) - -@<Assignments@>= -case set_font: define(cur_font_loc, data, cur_chr);@+break; - -@ When a |def| command has been scanned, -|cur_chr| is odd if the definition is supposed to be global, and -|cur_chr >= 2| if the definition is supposed to be expanded. - -@<Assignments@>= -case def: {@+if (odd(cur_chr)&&!global&&(global_defs >= 0)) a=a+4; - e=(cur_chr >= 2);get_r_token();p=cur_cs; - q=scan_toks(true, e); - if (j!=0) - {@+q=get_avail();info(q)=j;link(q)=link(def_ref); - link(def_ref)=q; - } - define(p, call+(a%4), def_ref); - } @+break; - -@ Both \.{\\let} and \.{\\futurelet} share the command code |let|. - -@<Put each...@>= -primitive("let", let, normal);@/ -@!@:let\_}{\.{\\let} primitive@> -primitive("futurelet", let, normal+1);@/ -@!@:future\_let\_}{\.{\\futurelet} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case let: if (chr_code!=normal) print_esc("futurelet");@+else print_esc("let");@+break; - -@ @<Assignments@>= -case let: {@+n=cur_chr; - get_r_token();p=cur_cs; - if (n==normal) - {@+@/do@+{get_token(); - }@+ while (!(cur_cmd!=spacer)); - if (cur_tok==other_token+'=') - {@+get_token(); - if (cur_cmd==spacer) get_token(); - } - } - else{@+get_token();q=cur_tok;get_token();back_input(); - cur_tok=q;back_input(); /*look ahead, then back up*/ - } /*note that |back_input| doesn't affect |cur_cmd|, |cur_chr|*/ - if (cur_cmd >= call) add_token_ref(cur_chr); - else if ((cur_cmd==internal_register)||(cur_cmd==toks_register)) - if ((cur_chr < mem_bot)||(cur_chr > lo_mem_stat_max)) - add_sa_ref(cur_chr); - define(p, cur_cmd, cur_chr); - } @+break; - -@ A \.{\\chardef} creates a control sequence whose |cmd| is |char_given|; -a \.{\\mathchardef} creates a control sequence whose |cmd| is |math_given|; -and the corresponding |chr| is the character code or math code. A \.{\\countdef} -or \.{\\dimendef} or \.{\\skipdef} or \.{\\muskipdef} creates a control -sequence whose |cmd| is |assign_int| or \dots\ or |assign_mu_glue|, and the -corresponding |chr| is the |eqtb| location of the internal register in question. - -@d char_def_code 0 /*|shorthand_def| for \.{\\chardef}*/ -@d math_char_def_code 1 /*|shorthand_def| for \.{\\mathchardef}*/ -@d count_def_code 2 /*|shorthand_def| for \.{\\countdef}*/ -@d dimen_def_code 3 /*|shorthand_def| for \.{\\dimendef}*/ -@d skip_def_code 4 /*|shorthand_def| for \.{\\skipdef}*/ -@d mu_skip_def_code 5 /*|shorthand_def| for \.{\\muskipdef}*/ -@d toks_def_code 6 /*|shorthand_def| for \.{\\toksdef}*/ - -@<Put each...@>= -primitive("chardef", shorthand_def, char_def_code);@/ -@!@:char\_def\_}{\.{\\chardef} primitive@> -primitive("mathchardef", shorthand_def, math_char_def_code);@/ -@!@:math\_char\_def\_}{\.{\\mathchardef} primitive@> -primitive("countdef", shorthand_def, count_def_code);@/ -@!@:count\_def\_}{\.{\\countdef} primitive@> -primitive("dimendef", shorthand_def, dimen_def_code);@/ -@!@:dimen\_def\_}{\.{\\dimendef} primitive@> -primitive("skipdef", shorthand_def, skip_def_code);@/ -@!@:skip\_def\_}{\.{\\skipdef} primitive@> -primitive("muskipdef", shorthand_def, mu_skip_def_code);@/ -@!@:mu\_skip\_def\_}{\.{\\muskipdef} primitive@> -primitive("toksdef", shorthand_def, toks_def_code);@/ -@!@:toks\_def\_}{\.{\\toksdef} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case shorthand_def: switch (chr_code) { - case char_def_code: print_esc("chardef");@+break; - case math_char_def_code: print_esc("mathchardef");@+break; - case count_def_code: print_esc("countdef");@+break; - case dimen_def_code: print_esc("dimendef");@+break; - case skip_def_code: print_esc("skipdef");@+break; - case mu_skip_def_code: print_esc("muskipdef");@+break; - default:print_esc("toksdef"); - } @+break; -case char_given: {@+print_esc("char");print_hex(chr_code); - } @+break; -case math_given: {@+print_esc("mathchar");print_hex(chr_code); - } @+break; - -@ We temporarily define |p| to be |relax|, so that an occurrence of |p| -while scanning the definition will simply stop the scanning instead of -producing an ``undefined control sequence'' error or expanding the -previous meaning. This allows, for instance, `\.{\\chardef\\foo=123\\foo}'. - -@<Assignments@>= -case shorthand_def: {@+n=cur_chr;get_r_token();p=cur_cs;define(p, relax, 256); - scan_optional_equals(); - switch (n) { - case char_def_code: {@+scan_char_num();define(p, char_given, cur_val); - } @+break; - case math_char_def_code: {@+scan_fifteen_bit_int();define(p, math_given, cur_val); - } @+break; - default:{@+scan_register_num(); - if (cur_val > 255) - {@+j=n-count_def_code; /*|int_val dotdot box_val|*/ - if (j > mu_val) j=tok_val; /*|int_val dotdot mu_val| or |tok_val|*/ - find_sa_element(j, cur_val, true);add_sa_ref(cur_ptr); - if (j==tok_val) j=toks_register;@+else j=internal_register; - define(p, j, cur_ptr); - } - else - switch (n) { - case count_def_code: define(p, assign_int, count_base+cur_val);@+break; - case dimen_def_code: define(p, assign_dimen, scaled_base+cur_val);@+break; - case skip_def_code: define(p, assign_glue, skip_base+cur_val);@+break; - case mu_skip_def_code: define(p, assign_mu_glue, mu_skip_base+cur_val);@+break; - case toks_def_code: define(p, assign_toks, toks_base+cur_val); - } /*there are no other cases*/ - } - } - } @+break; - -@ @<Assignments@>= -case read_to_cs: {@+j=cur_chr;scan_int();n=cur_val; - if (!scan_keyword("to")) -@.to@> - {@+print_err("Missing `to' inserted"); -@.Missing `to'...@> - help2("You should have said `\\read<number> to \\cs'.",@/ - "I'm going to look for the \\cs now.");error(); - } - get_r_token(); - p=cur_cs;read_toks(n, p, j);define(p, call, cur_val); - } @+break; - -@ The token-list parameters, \.{\\output} and \.{\\everypar}, etc., receive -their values in the following way. (For safety's sake, we place an -enclosing pair of braces around an \.{\\output} list.) - -@<Assignments@>= -case toks_register: case assign_toks: {@+q=cur_cs; - e=false; /*just in case, will be set |true| for sparse array elements*/ - if (cur_cmd==toks_register) - if (cur_chr==mem_bot) - {@+scan_register_num(); - if (cur_val > 255) - {@+find_sa_element(tok_val, cur_val, true); - cur_chr=cur_ptr;e=true; - } - else cur_chr=toks_base+cur_val; - } - else e=true; - p=cur_chr; /*|p==every_par_loc| or |output_routine_loc| or \dots*/ - scan_optional_equals(); - @<Get the next non-blank non-relax non-call token@>; - if (cur_cmd!=left_brace) @<If the right-hand side is a token parameter or token -register, finish the assignment and |goto done|@>; - back_input();cur_cs=q;q=scan_toks(false, false); - if (link(def_ref)==null) /*empty list: revert to the default*/ - {@+sa_define(p, null, p, undefined_cs, null);free_avail(def_ref); - } - else{@+if ((p==output_routine_loc)&&!e) /*enclose in curlies*/ - {@+link(q)=get_avail();q=link(q); - info(q)=right_brace_token+'}'; - q=get_avail();info(q)=left_brace_token+'{'; - link(q)=link(def_ref);link(def_ref)=q; - } - sa_define(p, def_ref, p, call, def_ref); - } - } @+break; - -@ @<If the right-hand side is a token parameter...@>= -if ((cur_cmd==toks_register)||(cur_cmd==assign_toks)) - {@+if (cur_cmd==toks_register) - if (cur_chr==mem_bot) - {@+scan_register_num(); - if (cur_val < 256) q=equiv(toks_base+cur_val); - else{@+find_sa_element(tok_val, cur_val, false); - if (cur_ptr==null) q=null; - else q=sa_ptr(cur_ptr); - } - } - else q=sa_ptr(cur_chr); - else q=equiv(cur_chr); - if (q==null) sa_define(p, null, p, undefined_cs, null); - else{@+add_token_ref(q);sa_define(p, q, p, call, q); - } - goto done; - } - -@ Similar routines are used to assign values to the numeric parameters. - -@<Assignments@>= -case assign_int: {@+p=cur_chr;scan_optional_equals();scan_int(); - word_define(p, cur_val); - } @+break; -case assign_dimen: {@+p=cur_chr;scan_optional_equals(); - scan_normal_dimen;word_define(p, cur_val); - } @+break; -case assign_glue: case assign_mu_glue: {@+p=cur_chr;n=cur_cmd;scan_optional_equals(); - if (n==assign_mu_glue) scan_glue(mu_val);@+else scan_glue(glue_val); - trap_zero_glue(); - define(p, glue_ref, cur_val); - } @+break; - -@ When a glue register or parameter becomes zero, it will always point to -|zero_glue| because of the following procedure. (Exception: The tabskip -glue isn't trapped while preambles are being scanned.) - -@<Declare subprocedures for |prefixed_command|@>= -static void trap_zero_glue(void) -{@+if ((width(cur_val)==0)&&(stretch(cur_val)==0)&&(shrink(cur_val)==0)) - {@+add_glue_ref(zero_glue); - delete_glue_ref(cur_val);cur_val=zero_glue; - } -} - -@ The various character code tables are changed by the |def_code| commands, -and the font families are declared by |def_family|. - -@<Put each...@>= -primitive("catcode", def_code, cat_code_base); -@!@:cat\_code\_}{\.{\\catcode} primitive@> -primitive("mathcode", def_code, math_code_base); -@!@:math\_code\_}{\.{\\mathcode} primitive@> -primitive("lccode", def_code, lc_code_base); -@!@:lc\_code\_}{\.{\\lccode} primitive@> -primitive("uccode", def_code, uc_code_base); -@!@:uc\_code\_}{\.{\\uccode} primitive@> -primitive("sfcode", def_code, sf_code_base); -@!@:sf\_code\_}{\.{\\sfcode} primitive@> -primitive("delcode", def_code, del_code_base); -@!@:del\_code\_}{\.{\\delcode} primitive@> -primitive("textfont", def_family, math_font_base); -@!@:text\_font\_}{\.{\\textfont} primitive@> -primitive("scriptfont", def_family, math_font_base+script_size); -@!@:script\_font\_}{\.{\\scriptfont} primitive@> -primitive("scriptscriptfont", def_family, math_font_base+script_script_size); -@!@:script\_script\_font\_}{\.{\\scriptscriptfont} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case def_code: if (chr_code==cat_code_base) print_esc("catcode"); - else if (chr_code==math_code_base) print_esc("mathcode"); - else if (chr_code==lc_code_base) print_esc("lccode"); - else if (chr_code==uc_code_base) print_esc("uccode"); - else if (chr_code==sf_code_base) print_esc("sfcode"); - else print_esc("delcode");@+break; -case def_family: print_size(chr_code-math_font_base);@+break; - -@ The different types of code values have different legal ranges; the -following program is careful to check each case properly. - -@<Assignments@>= -case def_code: {@+@<Let |n| be the largest legal code value, based on |cur_chr|@>; - p=cur_chr;scan_char_num();p=p+cur_val;scan_optional_equals(); - scan_int(); - if (((cur_val < 0)&&(p < del_code_base))||(cur_val > n)) - {@+print_err("Invalid code (");print_int(cur_val); -@.Invalid code@> - if (p < del_code_base) print("), should be in the range 0.."); - else print("), should be at most "); - print_int(n); - help1("I'm going to use 0 instead of that illegal code value.");@/ - error();cur_val=0; - } - if (p < math_code_base) define(p, data, cur_val); - else if (p < del_code_base) define(p, data, hi(cur_val)); - else word_define(p, cur_val); - } @+break; - -@ @<Let |n| be the largest...@>= -if (cur_chr==cat_code_base) n=max_char_code; -else if (cur_chr==math_code_base) n=0100000; -else if (cur_chr==sf_code_base) n=077777; -else if (cur_chr==del_code_base) n=077777777; -else n=255 - -@ @<Assignments@>= -case def_family: {@+p=cur_chr;scan_four_bit_int();p=p+cur_val; - scan_optional_equals();scan_font_ident();define(p, data, cur_val); - } @+break; - -@ Next we consider changes to \TeX's numeric registers. - -@<Assignments@>= -case internal_register: case advance: case multiply: case divide: do_register_command(a);@+break; - -@ We use the fact that |internal_register < advance < multiply < divide|. - -@<Declare subprocedures for |prefixed_command|@>= -static void do_register_command(small_number @!a) -{@+ -pointer l, @!q, @!r, @!s; /*for list manipulation*/ -int @!p; /*type of register involved*/ -bool @!e; /*does |l| refer to a sparse array element?*/ -int @!w; /*integer or dimen value of |l|*/ -q=cur_cmd; -e=false; /*just in case, will be set |true| for sparse array elements*/ -@<Compute the register location |l| and its type |p|; but |return| if invalid@>; -if (q==internal_register) scan_optional_equals(); -else if (scan_keyword("by")) do_nothing; /*optional `\.{by}'*/ -@.by@> -arith_error=false; -if (q < multiply) @<Compute result of |register| or |advance|, put it in |cur_val|@>@; -else@<Compute result of |multiply| or |divide|, put it in |cur_val|@>; -if (arith_error) - {@+print_err("Arithmetic overflow"); -@.Arithmetic overflow@> - help2("I can't carry out that multiplication or division,",@/ - "since the result is out of range."); - if (p >= glue_val) delete_glue_ref(cur_val); - error();return; - } -if (p < glue_val) sa_word_define(l, cur_val); -else{@+trap_zero_glue();sa_define(l, cur_val, l, glue_ref, cur_val); - } -} - -@ Here we use the fact that the consecutive codes |int_val dotdot mu_val| and -|assign_int dotdot assign_mu_glue| correspond to each other nicely. - -@<Compute the register location |l| and its type |p|...@>= -{@+if (q!=internal_register) - {@+get_x_token(); - if ((cur_cmd >= assign_int)&&(cur_cmd <= assign_mu_glue)) - {@+l=cur_chr;p=cur_cmd-assign_int;goto found; - } - if (cur_cmd!=internal_register) - {@+print_err("You can't use `");print_cmd_chr(cur_cmd, cur_chr); -@.You can't use x after ...@> - print("' after ");print_cmd_chr(q, 0); - help1("I'm forgetting what you said and not changing anything."); - error();return; - } - } -if ((cur_chr < mem_bot)||(cur_chr > lo_mem_stat_max)) - {@+l=cur_chr;p=sa_type(l);e=true; - } -else{@+p=cur_chr-mem_bot;scan_register_num(); - if (cur_val > 255) - {@+find_sa_element(p, cur_val, true);l=cur_ptr;e=true; - } - else -switch (p) { -case int_val: l=cur_val+count_base;@+break; -case dimen_val: l=cur_val+scaled_base;@+break; -case glue_val: l=cur_val+skip_base;@+break; -case mu_val: l=cur_val+mu_skip_base; -} /*there are no other cases*/ - } -} -found: if (p < glue_val) @+if (e) w=sa_int(l);@+else w=eqtb[l].i; -else if (e) s=sa_ptr(l);@+else s=equiv(l) - -@ @<Compute result of |register| or |advance|...@>= -if (p < glue_val) - {@+if (p==int_val) scan_int();@+else scan_normal_dimen; - if (q==advance) - { cur_val=cur_val+w; - if (!e && l>=dimen_base) - { cur_hfactor+=hfactor_eqtb[l].sc; - cur_vfactor+=vfactor_eqtb[l].sc; - } - } - } -else{@+scan_glue(p); - if (q==advance) @<Compute the sum of two glue specs@>; - } - -@ @<Compute the sum of two glue specs@>= -{@+q=new_spec(cur_val);r=s; -delete_glue_ref(cur_val); -width(q)=width(q)+width(r); -if (stretch(q)==0) stretch_order(q)=normal; -if (stretch_order(q)==stretch_order(r)) stretch(q)=stretch(q)+stretch(r); -else if ((stretch_order(q) < stretch_order(r))&&(stretch(r)!=0)) - {@+stretch(q)=stretch(r);stretch_order(q)=stretch_order(r); - } -if (shrink(q)==0) shrink_order(q)=normal; -if (shrink_order(q)==shrink_order(r)) shrink(q)=shrink(q)+shrink(r); -else if ((shrink_order(q) < shrink_order(r))&&(shrink(r)!=0)) - {@+shrink(q)=shrink(r);shrink_order(q)=shrink_order(r); - } -cur_val=q; -} - -@ @<Compute result of |multiply| or |divide|...@>= -{@+scan_int(); -if (p < glue_val) - if (q==multiply) - if (p==int_val) cur_val=mult_integers(w, cur_val); - else cur_val=nx_plus_y(w, cur_val, 0); - else cur_val=x_over_n(w, cur_val); -else{@+r=new_spec(s); - if (q==multiply) - {@+width(r)=nx_plus_y(width(s), cur_val, 0); - stretch(r)=nx_plus_y(stretch(s), cur_val, 0); - shrink(r)=nx_plus_y(shrink(s), cur_val, 0); - } - else{@+width(r)=x_over_n(width(s), cur_val); - stretch(r)=x_over_n(stretch(s), cur_val); - shrink(r)=x_over_n(shrink(s), cur_val); - } - cur_val=r; - } -} - -@ The processing of boxes is somewhat different, because we may need -to scan and create an entire box before we actually change the value of the old -one. - -@<Assignments@>= -case set_box: {@+scan_register_num(); - if (global) n=global_box_flag+cur_val;@+else n=box_flag+cur_val; - scan_optional_equals(); - if (set_box_allowed) scan_box(n); - else{@+print_err("Improper ");print_esc("setbox"); -@.Improper \\setbox@> - help2("Sorry, \\setbox is not allowed after \\halign in a display,",@/ - "or between \\accent and an accented character.");error(); - } - } @+break; - -@ The |space_factor| or |prev_depth| settings are changed when a |set_aux| -command is sensed. Similarly, |prev_graf| is changed in the presence of -|set_prev_graf|, and |dead_cycles| or |insert_penalties| in the presence of -|set_page_int|. These definitions are always global. - -When some dimension of a box register is changed, the change isn't exactly -global; but \TeX\ does not look at the \.{\\global} switch. - -@<Assignments@>= -case set_aux: alter_aux();@+break; -case set_prev_graf: alter_prev_graf();@+break; -case set_page_dimen: alter_page_so_far();@+break; -case set_page_int: alter_integer();@+break; -case set_box_dimen: alter_box_dimen();@+break; - -@ @<Declare subprocedures for |prefixed_command|@>= -static void alter_aux(void) -{@+halfword c; /*|hmode| or |vmode|*/ -if (cur_chr!=abs(mode)) report_illegal_case(); -else{@+c=cur_chr;scan_optional_equals(); - if (c==vmode) - {@+scan_normal_dimen;prev_depth=cur_val; - } - else{@+scan_int(); - if ((cur_val <= 0)||(cur_val > 32767)) - {@+print_err("Bad space factor"); -@.Bad space factor@> - help1("I allow only values in the range 1..32767 here."); - int_error(cur_val); - } - else space_factor=cur_val; - } - } -} - -@ @<Declare subprocedures for |prefixed_command|@>= -static void alter_prev_graf(void) -{@+int p; /*index into |nest|*/ -nest[nest_ptr]=cur_list;p=nest_ptr; -while (abs(nest[p].mode_field)!=vmode) decr(p); -scan_optional_equals();scan_int(); -if (cur_val < 0) - {@+print_err("Bad ");print_esc("prevgraf"); -@.Bad \\prevgraf@> - help1("I allow only nonnegative values here."); - int_error(cur_val); - } -else{@+nest[p].pg_field=cur_val;cur_list=nest[nest_ptr]; - } -} - -@ @<Declare subprocedures for |prefixed_command|@>= -static void alter_page_so_far(void) -{@+int c; /*index into |page_so_far|*/ -c=cur_chr;scan_optional_equals();scan_normal_dimen; -page_so_far[c]=cur_val; -} - -@ @<Declare subprocedures for |prefixed_command|@>= -static void alter_integer(void) -{@+small_number c; - /*0 for \.{\\deadcycles}, 1 for \.{\\insertpenalties}, etc.*/ -c=cur_chr;scan_optional_equals();scan_int(); -if (c==0) dead_cycles=cur_val -@/@<Cases for |alter_integer|@>@;@/ -else insert_penalties=cur_val; -} - -@ @<Declare subprocedures for |prefixed_command|@>= -static void alter_box_dimen(void) -{@+small_number c; /*|width_offset| or |height_offset| or |depth_offset|*/ -pointer @!b; /*box register*/ -c=cur_chr;scan_register_num();fetch_box(b);scan_optional_equals(); -scan_normal_dimen; -if (b!=null) mem[b+c].sc=cur_val; -} - -@ Paragraph shapes are set up in the obvious way. - -@<Assignments@>= -case set_shape: {@+q=cur_chr;scan_optional_equals();scan_int();n=cur_val; - if (n <= 0) p=null; - else if (q > par_shape_loc) - {@+n=(cur_val/2)+1;p=get_node(2*n+1);info(p)=n; - n=cur_val;mem[p+1].i=n; /*number of penalties*/ - for (j=p+2; j<=p+n+1; j++) - {@+scan_int();mem[j].i=cur_val; /*penalty values*/ - } - if (!odd(n)) mem[p+n+2].i=0; /*unused*/ - } - else{@+ - scaled fh=0, fv=0; - p=get_node(2*n+1);info(p)=n; - for (j=1; j<=n; j++) - {@+scan_normal_dimen; - mem[p+2*j-1].sc=cur_val; /*indentation*/ - scan_normal_dimen; - if (j==1) {fh=cur_hfactor; fv=cur_vfactor;} - mem[p+2*j].sc=cur_val; /*width*/ - } - cur_hfactor=fh; cur_vfactor=fv; - } - define(q, shape_ref, p); - } @+break; - -@ Here's something that isn't quite so obvious. It guarantees that -|info(par_shape_ptr)| can hold any positive~|n| for which |get_node(2*n+1)| -doesn't overflow the memory capacity. - -@<Check the ``constant''...@>= -if (2*max_halfword < mem_top-mem_min) bad=41; - -@ New hyphenation data is loaded by the |hyph_data| command. - -@<Put each...@>= -primitive("hyphenation", hyph_data, 0); -@!@:hyphenation\_}{\.{\\hyphenation} primitive@> -primitive("patterns", hyph_data, 1); -@!@:patterns\_}{\.{\\patterns} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case hyph_data: if (chr_code==1) print_esc("patterns"); - else print_esc("hyphenation");@+break; - -@ @<Assignments@>= -case hyph_data: if (cur_chr==1) - { -#ifdef @!INIT -new_patterns();goto done;@; -#endif - print_err("Patterns can be loaded only by INITEX"); -@.Patterns can be...@> - help0;error(); - @/do@+{get_token();}@+ while (!(cur_cmd==right_brace)); /*flush the patterns*/ - return; - } - else{@+new_hyph_exceptions();goto done; - } @+break; - -@ All of \TeX's parameters are kept in |eqtb| except the font information, -the interaction mode, and the hyphenation tables; these are strictly global. - -@<Assignments@>= -case assign_font_dimen: {@+find_font_dimen(true);k=cur_val; - scan_optional_equals();scan_normal_dimen;font_info[k].sc=cur_val; - } @+break; -case assign_font_int: {@+n=cur_chr;scan_font_ident();f=cur_val; - scan_optional_equals();scan_int(); - if (n==0) hyphen_char[f]=cur_val;@+else skew_char[f]=cur_val; - } @+break; - -@ @<Put each...@>= -primitive("hyphenchar", assign_font_int, 0); -@!@:hyphen\_char\_}{\.{\\hyphenchar} primitive@> -primitive("skewchar", assign_font_int, 1); -@!@:skew\_char\_}{\.{\\skewchar} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case assign_font_int: if (chr_code==0) print_esc("hyphenchar"); - else print_esc("skewchar");@+break; - -@ Here is where the information for a new font gets loaded. - -@<Assignments@>= -case def_font: new_font(a);@+break; - -@ @<Declare subprocedures for |prefixed_command|@>= -static void new_font(small_number @!a) -{@+ -pointer u; /*user's font identifier*/ -scaled @!s; /*stated ``at'' size, or negative of scaled magnification*/ -int @!f; /*runs through existing fonts*/ -str_number @!t; /*name for the frozen font identifier*/ -int @!old_setting; /*holds |selector| setting*/ -str_number @!flushable_string; /*string not yet referenced*/ -if (job_name==0) open_log_file(); - /*avoid confusing \.{texput} with the font name*/ -@.texput@> -get_r_token();u=cur_cs; -if (u >= hash_base) t=text(u); -else if (u >= single_base) - if (u==null_cs) t=s_no("FONT");@+else t=u-single_base; -else{@+old_setting=selector;selector=new_string; - print("FONT");printn(u-active_base);selector=old_setting; -@.FONTx@> - str_room(1);t=make_string(); - } -define(u, set_font, null_font);scan_optional_equals();scan_file_name(); -@<Scan the font size specification@>; -@<If this font has already been loaded, set |f| to the internal font number and |goto -common_ending|@>; -f=read_font_info(u, cur_name, cur_area, s); -common_ending: define(u, set_font, f);eqtb[font_id_base+f]=eqtb[u];font_id_text(f)=t; -} - -@ @<Scan the font size specification@>= -name_in_progress=true; /*this keeps |cur_name| from being changed*/ -if (scan_keyword("at")) @<Put the \(p)(positive) `at' size into |s|@>@; -@.at@> -else if (scan_keyword("scaled")) -@.scaled@> - {@+scan_int();s=-cur_val; - if ((cur_val <= 0)||(cur_val > 32768)) - {@+print_err("Illegal magnification has been changed to 1000");@/ -@.Illegal magnification...@> - help1("The magnification ratio must be between 1 and 32768."); - int_error(cur_val);s=-1000; - } - } -else s=-1000; -name_in_progress=false - -@ @<Put the \(p)(positive) `at' size into |s|@>= -{@+scan_normal_dimen;s=cur_val; -if ((s <= 0)||(s >= 01000000000)) - {@+print_err("Improper `at' size ("); - print_scaled(s);print("pt), replaced by 10pt"); -@.Improper `at' size...@> - help2("I can only handle fonts at positive sizes that are",@/ - "less than 2048pt, so I've changed what you said to 10pt."); - error();s=10*unity; - } -} - -@ When the user gives a new identifier to a font that was previously loaded, -the new name becomes the font identifier of record. Font names `\.{xyz}' and -`\.{XYZ}' are considered to be different. - -@<If this font has already been loaded...@>= -flushable_string=str_ptr-1; -for (f=font_base+1; f<=font_ptr; f++) - if (strn_eq_str(font_name[f], cur_name)&&str_eq_str(font_area[f], cur_area)) - {@+if (cur_name==flushable_string) - {@+flush_string;cur_name=font_name[f]; - } - if (s > 0) - {@+if (s==font_size[f]) goto common_ending; - } - else if (font_size[f]==xn_over_d(font_dsize[f],-s, 1000)) - goto common_ending; - } - -@ @<Cases of |print_cmd_chr|...@>= -case set_font: {@+print("select font ");slow_print(font_name[chr_code]); - if (font_size[chr_code]!=font_dsize[chr_code]) - {@+print(" at ");print_scaled(font_size[chr_code]); - print("pt"); - } - } @+break; - -@ @<Put each...@>= -primitive("batchmode", set_interaction, batch_mode); -@!@:batch\_mode\_}{\.{\\batchmode} primitive@> -primitive("nonstopmode", set_interaction, nonstop_mode); -@!@:nonstop\_mode\_}{\.{\\nonstopmode} primitive@> -primitive("scrollmode", set_interaction, scroll_mode); -@!@:scroll\_mode\_}{\.{\\scrollmode} primitive@> -primitive("errorstopmode", set_interaction, error_stop_mode); -@!@:error\_stop\_mode\_}{\.{\\errorstopmode} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case set_interaction: switch (chr_code) { - case batch_mode: print_esc("batchmode");@+break; - case nonstop_mode: print_esc("nonstopmode");@+break; - case scroll_mode: print_esc("scrollmode");@+break; - default:print_esc("errorstopmode"); - } @+break; - -@ @<Assignments@>= -case set_interaction: new_interaction();@+break; - -@ @<Declare subprocedures for |prefixed_command|@>= -static void new_interaction(void) -{@+print_ln(); -interaction=cur_chr; -@<Initialize the print |selector| based on |interaction|@>; -if (log_opened) selector=selector+2; -} - -@ The \.{\\afterassignment} command puts a token into the global -variable |after_token|. This global variable is examined just after -every assignment has been performed. - -@<Glob...@>= -static halfword @!after_token; /*zero, or a saved token*/ - -@ @<Set init...@>= -after_token=0; - -@ @<Cases of |main_control| that don't...@>= -any_mode(after_assignment): {@+get_token();after_token=cur_tok; - } @+break; - -@ @<Insert a token saved by \.{\\afterassignment}, if any@>= -if (after_token!=0) - {@+cur_tok=after_token;back_input();after_token=0; - } - -@ Here is a procedure that might be called `Get the next non-blank non-relax -non-call non-assignment token'. - -@<Declare act...@>= -static void do_assignments(void) -{@+ -loop{@+@<Get the next non-blank non-relax...@>; - if (cur_cmd <= max_non_prefixed_command) return; - set_box_allowed=false;prefixed_command();set_box_allowed=true; - } -} - -@ @<Cases of |main_control| that don't...@>= -any_mode(after_group): {@+get_token();save_for_after(cur_tok); - } @+break; - -@ Files for \.{\\read} are opened and closed by the |in_stream| command. - -@<Put each...@>= -primitive("openin", in_stream, 1); -@!@:open\_in\_}{\.{\\openin} primitive@> -primitive("closein", in_stream, 0); -@!@:close\_in\_}{\.{\\closein} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case in_stream: if (chr_code==0) print_esc("closein"); - else print_esc("openin");@+break; - -@ @<Cases of |main_control| that don't...@>= -any_mode(in_stream): open_or_close_in();@+break; - -@ @<Declare act...@>= -static void open_or_close_in(void) -{@+int c; /*1 for \.{\\openin}, 0 for \.{\\closein}*/ -int @!n; /*stream number*/ -c=cur_chr;scan_four_bit_int();n=cur_val; -if (read_open[n]!=closed) - {@+a_close(&read_file[n]);read_open[n]=closed; - } -if (c!=0) - {@+scan_optional_equals();scan_file_name(); - if (cur_ext[0]==0) cur_ext=".tex"; - pack_cur_name; - if (a_open_in(&read_file[n])) read_open[n]=just_open; - } -} - -@ The user can issue messages to the terminal, regardless of the -current mode. - -@<Cases of |main_control| that don't...@>= -any_mode(message): issue_message();@+break; - -@ @<Put each...@>= -primitive("message", message, 0); -@!@:message\_}{\.{\\message} primitive@> -primitive("errmessage", message, 1); -@!@:err\_message\_}{\.{\\errmessage} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case message: if (chr_code==0) print_esc("message"); - else print_esc("errmessage");@+break; - -@ @<Declare act...@>= -static void issue_message(void) -{@+int old_setting; /*holds |selector| setting*/ -int @!c; /*identifies \.{\\message} and \.{\\errmessage}*/ -str_number @!s; /*the message*/ -c=cur_chr;link(garbage)=scan_toks(false, true); -old_setting=selector;selector=new_string; -token_show(def_ref);selector=old_setting; -flush_list(def_ref); -str_room(1);s=make_string(); -if (c==0) @<Print string |s| on the terminal@>@; -else@<Print string |s| as an error message@>; -flush_string; -} - -@ @<Print string |s| on the terminal@>= -{@+if (term_offset+length(s) > max_print_line-2) print_ln(); -else if ((term_offset > 0)||(file_offset > 0)) print_char(' '); -slow_print(s);update_terminal; -} - -@ If \.{\\errmessage} occurs often in |scroll_mode|, without user-defined -\.{\\errhelp}, we don't want to give a long help message each time. So we -give a verbose explanation only once. - -@<Glob...@>= -static bool @!long_help_seen; /*has the long \.{\\errmessage} help been used?*/ - -@ @<Set init...@>=long_help_seen=false; - -@ @<Print string |s| as an error message@>= -{@+print_err("");slow_print(s); -if (err_help!=null) use_err_help=true; -else if (long_help_seen) help1("(That was another \\errmessage.)")@; -else{@+if (interaction < error_stop_mode) long_help_seen=true; - help4("This error message was generated by an \\errmessage",@/ - "command, so I can't give any explicit help.",@/ - "Pretend that you're Hercule Poirot: Examine all clues,",@/ -@^Poirot, Hercule@> - "and deduce the truth by order and method."); - } -error();use_err_help=false; -} - -@ The |error| routine calls on |give_err_help| if help is requested from -the |err_help| parameter. - -@p static void give_err_help(void) -{@+token_show(err_help); -} - -@ The \.{\\uppercase} and \.{\\lowercase} commands are implemented by -building a token list and then changing the cases of the letters in it. - -@<Cases of |main_control| that don't...@>= -any_mode(case_shift): shift_case();@+break; - -@ @<Put each...@>= -primitive("lowercase", case_shift, lc_code_base); -@!@:lowercase\_}{\.{\\lowercase} primitive@> -primitive("uppercase", case_shift, uc_code_base); -@!@:uppercase\_}{\.{\\uppercase} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case case_shift: if (chr_code==lc_code_base) print_esc("lowercase"); - else print_esc("uppercase");@+break; - -@ @<Declare act...@>= -static void shift_case(void) -{@+pointer b; /*|lc_code_base| or |uc_code_base|*/ -pointer @!p; /*runs through the token list*/ -halfword @!t; /*token*/ -eight_bits @!c; /*character code*/ -b=cur_chr;p=scan_toks(false, false);p=link(def_ref); -while (p!=null) - {@+@<Change the case of the token in |p|, if a change is appropriate@>; - p=link(p); - } -back_list(link(def_ref));free_avail(def_ref); /*omit reference count*/ -} - -@ When the case of a |chr_code| changes, we don't change the |cmd|. -We also change active characters, using the fact that -|cs_token_flag+active_base| is a multiple of~256. -@^data structure assumptions@> - -@<Change the case of the token in |p|, if a change is appropriate@>= -t=info(p); -if (t < cs_token_flag+single_base) - {@+c=t%256; - if (equiv(b+c)!=0) info(p)=t-c+equiv(b+c); - } - -@ We come finally to the last pieces missing from |main_control|, namely the -`\.{\\show}' commands that are useful when debugging. - -@<Cases of |main_control| that don't...@>= -any_mode(xray): show_whatever();@+break; - -@ @d show_code 0 /* \.{\\show} */ -@d show_box_code 1 /* \.{\\showbox} */ -@d show_the_code 2 /* \.{\\showthe} */ -@d show_lists_code 3 /* \.{\\showlists} */ - -@<Put each...@>= -primitive("show", xray, show_code); -@!@:show\_}{\.{\\show} primitive@> -primitive("showbox", xray, show_box_code); -@!@:show\_box\_}{\.{\\showbox} primitive@> -primitive("showthe", xray, show_the_code); -@!@:show\_the\_}{\.{\\showthe} primitive@> -primitive("showlists", xray, show_lists_code); -@!@:show\_lists\_code\_}{\.{\\showlists} primitive@> - -@ @<Cases of |print_cmd_chr|...@>= -case xray: switch (chr_code) { - case show_box_code: print_esc("showbox");@+break; - case show_the_code: print_esc("showthe");@+break; - case show_lists_code: print_esc("showlists");@+break; - @<Cases of |xray| for |print_cmd_chr|@>@;@/ - default:print_esc("show"); - } @+break; - -@ @<Declare act...@>= -static void show_whatever(void) -{@+ -pointer p; /*tail of a token list to show*/ -small_number @!t; /*type of conditional being shown*/ -int @!m; /*upper bound on |fi_or_else| codes*/ -int @!l; /*line where that conditional began*/ -int @!n; /*level of \.{\\if...\\fi} nesting*/ -switch (cur_chr) { -case show_lists_code: {@+begin_diagnostic();show_activities(); - } @+break; -case show_box_code: @<Show the current contents of a box@>@;@+break; -case show_code: @<Show the current meaning of a token, then |goto common_ending|@>@; -@<Cases for |show_whatever|@>@;@/ -default:@<Show the current value of some parameter or register, then |goto common_ending|@>@; -} @/ -@<Complete a potentially long \.{\\show} command@>; -common_ending: if (interaction < error_stop_mode) - {@+help0;decr(error_count); - } -else if (tracing_online > 0) - {@+@t@>@;@/ - help3("This isn't an error message; I'm just \\showing something.",@/ - "Type `I\\show...' to show more (e.g., \\show\\cs,",@/ - "\\showthe\\count10, \\showbox255, \\showlists)."); - } -else{@+@t@>@;@/ - help5("This isn't an error message; I'm just \\showing something.",@/ - "Type `I\\show...' to show more (e.g., \\show\\cs,",@/ - "\\showthe\\count10, \\showbox255, \\showlists).",@/ - "And type `I\\tracingonline=1\\show...' to show boxes and",@/ - "lists on your terminal as well as in the transcript file."); - } -error(); -} - -@ @<Show the current meaning of a token...@>= -{@+get_token(); -if (interaction==error_stop_mode) wake_up_terminal; -print_nl("> "); -if (cur_cs!=0) - {@+sprint_cs(cur_cs);print_char('='); - } -print_meaning();goto common_ending; -} - -@ @<Cases of |print_cmd_chr|...@>= -case undefined_cs: print("undefined");@+break; -case call: case long_call: case outer_call: case long_outer_call: {@+n=cmd-call; - if (info(link(chr_code))==protected_token) n=n+4; - if (odd(n/4)) print_esc("protected"); - if (odd(n)) print_esc("long"); - if (odd(n/2)) print_esc("outer"); - if (n > 0) print_char(' '); - print("macro"); - } @+break; -case end_template: print_esc("outer endtemplate");@+break; - -@ @<Show the current contents of a box@>= -{@+scan_register_num();fetch_box(p);begin_diagnostic(); -print_nl("> \\box");print_int(cur_val);print_char('='); -if (p==null) print("void");@+else show_box(p); -} - -@ @<Show the current value of some parameter...@>= -{@+the_toks(); -if (interaction==error_stop_mode) wake_up_terminal; -print_nl("> ");token_show(temp_head); -flush_list(link(temp_head));goto common_ending; -} - -@ @<Complete a potentially long \.{\\show} command@>= -end_diagnostic(true);print_err("OK"); -@.OK@> -if (selector==term_and_log) if (tracing_online <= 0) - {@+selector=term_only;print(" (see the transcript file)"); - selector=term_and_log; - } - -@* Dumping and undumping the tables. -After \.{INITEX} has seen a collection of fonts and macros, it -can write all the necessary information on an auxiliary file so -that production versions of \TeX\ are able to initialize their -memory at high speed. The present section of the program takes -care of such output and input. We shall consider simultaneously -the processes of storing and restoring, -so that the inverse relation between them is clear. -@.INITEX@> - -The global variable |format_ident| is a string that is printed right -after the |banner| line when \TeX\ is ready to start. For \.{INITEX} this -string says simply `\.{ (INITEX)}'; for other versions of \TeX\ it says, -for example, `\.{ (preloaded format=plain 1982.11.19)}', showing the year, -month, and day that the format file was created. We have |format_ident==0| -before \TeX's tables are loaded. - -@<Glob...@>= -static str_number @!format_ident; - -@ @<Set init...@>= -format_ident=0; - -@ @<Initialize table entries...@>= -format_ident=s_no(" (INITEX)"); - -@ @<Declare act...@>= -#ifdef @!INIT -static void store_fmt_file(void) -{@+ -int j, @!k, @!l; /*all-purpose indices*/ -int @!p, @!q; /*all-purpose pointers*/ -int @!x; /*something to dump*/ -four_quarters @!w; /*four ASCII codes*/ -@<If dumping is not allowed, abort@>; -@<Create the |format_ident|, open the format file, and inform the user that dumping -has begun@>; -eqtb[dimen_base+hsize_code].i=hhsize; -eqtb[dimen_base+vsize_code].i=hvsize; -@<Dump constants for consistency check@>; -@<Dump the string pool@>; -@<Dump the dynamic memory@>; -@<Dump the table of equivalents@>; -@<Dump the font information@>; -@<Dump the hyphenation tables@>; -@<Dump a couple more things and the closing check word@>; -@<Close the format file@>; -eqtb[dimen_base+hsize_code].i=0; -eqtb[dimen_base+vsize_code].i=0; -} -#endif - -@ Corresponding to the procedure that dumps a format file, we have a function -that reads one in. The function returns |false| if the dumped format is -incompatible with the present \TeX\ table sizes, etc. - -@d too_small(X) {@+wake_up_terminal; - wterm_ln("---! Must increase the %s", X); -@.Must increase the x@> - goto bad_fmt; - } - -@p @t\4@>@<Declare the function called |open_fmt_file|@>@; -static bool load_fmt_file(void) -{@+ -int j, @!k; /*all-purpose indices*/ -int @!p, @!q; /*all-purpose pointers*/ -int @!x; /*something undumped*/ -four_quarters @!w; /*four ASCII codes*/ -@<Undump constants for consistency check@>; -@<Undump the string pool@>; -@<Undump the dynamic memory@>; -@<Undump the table of equivalents@>; -@<Undump the font information@>; -@<Undump the hyphenation tables@>; -@<Undump a couple more things and the closing check word@>; -return true; /*it worked!*/ -bad_fmt: wake_up_terminal; - wterm_ln("(Fatal format file error; I'm stymied)"); -@.Fatal format file error@> -return false; -} - -@ The user is not allowed to dump a format file unless |save_ptr==0|. -This condition implies that |cur_level==level_one|, hence -the |xeq_level| array is constant and it need not be dumped. - -@<If dumping is not allowed, abort@>= -if (save_ptr!=0) - {@+print_err("You can't dump inside a group"); -@.You can't dump...@> - help1("`{...\\dump}' is a no-no.");succumb; - } - -@ Format files consist of |memory_word| items, and we use the following -macros to dump words of different types: - -@d dump_wd(A) {@+fmt_file.d=A;put(fmt_file);@+} -@d dump_int(A) {@+fmt_file.d.i=A;put(fmt_file);@+} -@d dump_hh(A) {@+fmt_file.d.hh=A;put(fmt_file);@+} -@d dump_qqqq(A) {@+fmt_file.d.qqqq=A;put(fmt_file);@+} - -@<Glob...@>= -static word_file @!fmt_file; /*for input or output of format information*/ - -@ The inverse macros are slightly more complicated, since we need to check -the range of the values we are reading in. We say `|undump(a)(b)(x)|' to -read an integer value |x| that is supposed to be in the range |a <= x <= b|. -System error messages should be suppressed when undumping. -@^system dependencies@> - -@d undump_wd(A) {@+get(fmt_file);A=fmt_file.d;@+} -@d undump_int(A) {@+get(fmt_file);A=fmt_file.d.i;@+} -@d undump_hh(A) {@+get(fmt_file);A=fmt_file.d.hh;@+} -@d undump_qqqq(A) {@+get(fmt_file);A=fmt_file.d.qqqq;@+} -@d undump(A, B, C) {@+undump_int(x);if ((x < A)||(x > B)) goto bad_fmt;@+else C=x;@+} -@d undump_size(A, B, C, D) {@+undump_int(x); - if (x < A) goto bad_fmt;if (x > B) too_small(C)@;@+else D=x;@+} - -@ The next few sections of the program should make it clear how we use the -dump/undump macros. - -@<Dump constants for consistency check@>= -dump_int(0);@/ -@<Dump the \eTeX\ state@>@/ -dump_int(mem_bot);@/ -dump_int(mem_top);@/ -dump_int(eqtb_size);@/ -dump_int(hash_prime);@/ -dump_int(hyph_size) - -@ Sections of a \.{WEB} program that are ``commented out'' still contribute -strings to the string pool; therefore \.{INITEX} and \TeX\ will have -the same strings. (And it is, of course, a good thing that they do.) -@.WEB@> -@^string pool@> - -@<Undump constants for consistency check@>= -x=fmt_file.d.i; -if (x!=0) goto bad_fmt; /*check that strings are the same*/ -@/@<Undump the \eTeX\ state@>@/ -undump_int(x); -if (x!=mem_bot) goto bad_fmt; -undump_int(x); -if (x!=mem_top) goto bad_fmt; -undump_int(x); -if (x!=eqtb_size) goto bad_fmt; -undump_int(x); -if (x!=hash_prime) goto bad_fmt; -undump_int(x); -if (x!=hyph_size) goto bad_fmt - -@ @d dump_four_ASCII - w.b0=qi(so(str_pool[k]));w.b1=qi(so(str_pool[k+1])); - w.b2=qi(so(str_pool[k+2]));w.b3=qi(so(str_pool[k+3])); - dump_qqqq(w) - -@<Dump the string pool@>= -dump_int(pool_ptr); -dump_int(str_ptr); -for (k=0; k<=str_ptr; k++) dump_int(str_start[k]); -k=0; -while (k+4 < pool_ptr) - {@+dump_four_ASCII;k=k+4; - } -k=pool_ptr-4;dump_four_ASCII; -print_ln();print_int(str_ptr);print(" strings of total length "); -print_int(pool_ptr) - -@ @d undump_four_ASCII - undump_qqqq(w); - str_pool[k]=si(qo(w.b0));str_pool[k+1]=si(qo(w.b1)); - str_pool[k+2]=si(qo(w.b2));str_pool[k+3]=si(qo(w.b3)) - -@<Undump the string pool@>= -undump_size(0, pool_size,"string pool size", pool_ptr); -undump_size(0, max_strings,"max strings", str_ptr); -for (k=0; k<=str_ptr; k++) undump(0, pool_ptr, str_start[k]); -k=0; -while (k+4 < pool_ptr) - {@+undump_four_ASCII;k=k+4; - } -k=pool_ptr-4;undump_four_ASCII; -init_str_ptr=str_ptr;init_pool_ptr=pool_ptr - -@ By sorting the list of available spaces in the variable-size portion of -|mem|, we are usually able to get by without having to dump very much -of the dynamic memory. - -We recompute |var_used| and |dyn_used|, so that \.{INITEX} dumps valid -information even when it has not been gathering statistics. - -@<Dump the dynamic memory@>= -sort_avail();var_used=0; -dump_int(lo_mem_max);dump_int(rover); -if (eTeX_ex) for (k=int_val; k<=tok_val; k++) dump_int(sa_root[k]); -p=mem_bot;q=rover;x=0; -@/do@+{for (k=p; k<=q+1; k++) dump_wd(mem[k]); -x=x+q+2-p;var_used=var_used+q-p; -p=q+node_size(q);q=rlink(q); -}@+ while (!(q==rover)); -var_used=var_used+lo_mem_max-p;dyn_used=mem_end+1-hi_mem_min;@/ -for (k=p; k<=lo_mem_max; k++) dump_wd(mem[k]); -x=x+lo_mem_max+1-p; -dump_int(hi_mem_min);dump_int(avail); -for (k=hi_mem_min; k<=mem_end; k++) dump_wd(mem[k]); -x=x+mem_end+1-hi_mem_min; -p=avail; -while (p!=null) - {@+decr(dyn_used);p=link(p); - } -dump_int(var_used);dump_int(dyn_used); -print_ln();print_int(x); -print(" memory locations dumped; current usage is "); -print_int(var_used);print_char('&');print_int(dyn_used) - -@ @<Undump the dynamic memory@>= -undump(lo_mem_stat_max+1000, hi_mem_stat_min-1, lo_mem_max); -undump(lo_mem_stat_max+1, lo_mem_max, rover); -if (eTeX_ex) for (k=int_val; k<=tok_val; k++) - undump(null, lo_mem_max, sa_root[k]); -p=mem_bot;q=rover; -@/do@+{for (k=p; k<=q+1; k++) undump_wd(mem[k]); -p=q+node_size(q); -if ((p > lo_mem_max)||((q >= rlink(q))&&(rlink(q)!=rover))) goto bad_fmt; -q=rlink(q); -}@+ while (!(q==rover)); -for (k=p; k<=lo_mem_max; k++) undump_wd(mem[k]); -if (mem_min < mem_bot-2) /*make more low memory available*/ - {@+p=llink(rover);q=mem_min+1; - link(mem_min)=null;info(mem_min)=null; /*we don't use the bottom word*/ - rlink(p)=q;llink(rover)=q;@/ - rlink(q)=rover;llink(q)=p;link(q)=empty_flag; - node_size(q)=mem_bot-q; - } -undump(lo_mem_max+1, hi_mem_stat_min, hi_mem_min); -undump(null, mem_top, avail);mem_end=mem_top; -for (k=hi_mem_min; k<=mem_end; k++) undump_wd(mem[k]); -undump_int(var_used);undump_int(dyn_used) - -@ @<Dump the table of equivalents@>= -@<Dump regions 1 to 4 of |eqtb|@>; -@<Dump regions 5 and 6 of |eqtb|@>; -dump_int(par_loc);dump_int(write_loc);@/ -@<Dump the hash table@>@; - -@ @<Undump the table of equivalents@>= -@<Undump regions 1 to 6 of |eqtb|@>; -undump(hash_base, frozen_control_sequence, par_loc); -par_token=cs_token_flag+par_loc;@/ -undump(hash_base, frozen_control_sequence, write_loc);@/ -@<Undump the hash table@>@; - -@ The table of equivalents usually contains repeated information, so we dump it -in compressed form: The sequence of $n+2$ values $(n,x_1,\ldots,x_n,m)$ in the -format file represents $n+m$ consecutive entries of |eqtb|, with |m| extra -copies of $x_n$, namely $(x_1,\ldots,x_n,x_n,\ldots,x_n)$. - -@<Dump regions 1 to 4 of |eqtb|@>= -k=active_base; -@/do@+{j=k; -while (j < int_base-1) - {@+if ((equiv(j)==equiv(j+1))&&(eq_type(j)==eq_type(j+1))&&@| - (eq_level(j)==eq_level(j+1))) goto found1; - incr(j); - } -l=int_base;goto done1; /*|j==int_base-1|*/ -found1: incr(j);l=j; -while (j < int_base-1) - {@+if ((equiv(j)!=equiv(j+1))||(eq_type(j)!=eq_type(j+1))||@| - (eq_level(j)!=eq_level(j+1))) goto done1; - incr(j); - } -done1: dump_int(l-k); -while (k < l) - {@+dump_wd(eqtb[k]);incr(k); - } -k=j+1;dump_int(k-l); -}@+ while (!(k==int_base)) - -@ @<Dump regions 5 and 6 of |eqtb|@>= -@/do@+{j=k; -while (j < eqtb_size) - {@+if (eqtb[j].i==eqtb[j+1].i) goto found2; - incr(j); - } -l=eqtb_size+1;goto done2; /*|j==eqtb_size|*/ -found2: incr(j);l=j; -while (j < eqtb_size) - {@+if (eqtb[j].i!=eqtb[j+1].i) goto done2; - incr(j); - } -done2: dump_int(l-k); -while (k < l) - {@+dump_wd(eqtb[k]);incr(k); - } -k=j+1;dump_int(k-l); -}@+ while (!(k > eqtb_size)) - -@ @<Undump regions 1 to 6 of |eqtb|@>= -k=active_base; -@/do@+{undump_int(x); -if ((x < 1)||(k+x > eqtb_size+1)) goto bad_fmt; -for (j=k; j<=k+x-1; j++) undump_wd(eqtb[j]); -k=k+x; -undump_int(x); -if ((x < 0)||(k+x > eqtb_size+1)) goto bad_fmt; -for (j=k; j<=k+x-1; j++) eqtb[j]=eqtb[k-1]; -k=k+x; -}@+ while (!(k > eqtb_size)) - -@ A different scheme is used to compress the hash table, since its lower -region is usually sparse. When |text(p)!=0| for |p <= hash_used|, we output -two words, |p| and |hash[p]|. The hash table is, of course, densely packed -for |p >= hash_used|, so the remaining entries are output in a~block. - -@<Dump the hash table@>= -dump_int(hash_used);cs_count=frozen_control_sequence-1-hash_used; -for (p=hash_base; p<=hash_used; p++) if (text(p)!=0) - {@+dump_int(p);dump_hh(hash[p]);incr(cs_count); - } -for (p=hash_used+1; p<=undefined_control_sequence-1; p++) dump_hh(hash[p]); -dump_int(cs_count);@/ -print_ln();print_int(cs_count);print(" multiletter control sequences") - -@ @<Undump the hash table@>= -undump(hash_base, frozen_control_sequence, hash_used);p=hash_base-1; -@/do@+{undump(p+1, hash_used, p);undump_hh(hash[p]); -}@+ while (!(p==hash_used)); -for (p=hash_used+1; p<=undefined_control_sequence-1; p++) undump_hh(hash[p]); -undump_int(cs_count) - -@ @<Dump the font information@>= -dump_int(fmem_ptr); -for (k=0; k<=fmem_ptr-1; k++) dump_wd(font_info[k]); -dump_int(font_ptr); -for (k=null_font; k<=font_ptr; k++) - @<Dump the array info for internal font number |k|@>; -print_ln();print_int(fmem_ptr-7);print(" words of font info for "); -print_int(font_ptr-font_base);print(" preloaded font"); -if (font_ptr!=font_base+1) print_char('s') - -@ @<Undump the font information@>= -undump_size(7, font_mem_size,"font mem size", fmem_ptr); -for (k=0; k<=fmem_ptr-1; k++) undump_wd(font_info[k]); -undump_size(font_base, font_max,"font max", font_ptr); -for (k=null_font; k<=font_ptr; k++) - @<Undump the array info for internal font number |k|@>@; - -@ @<Dump the array info for internal font number |k|@>= -{@+dump_qqqq(font_check[k]); -dump_int(font_size[k]); -dump_int(font_dsize[k]); -dump_int(font_params[k]);@/ -dump_int(hyphen_char[k]); -dump_int(skew_char[k]);@/ -dump_int(font_name[k]); -dump_int(font_area[k]);@/ -dump_int(font_bc[k]); -dump_int(font_ec[k]);@/ -dump_int(char_base[k]); -dump_int(width_base[k]); -dump_int(height_base[k]);@/ -dump_int(depth_base[k]); -dump_int(italic_base[k]); -dump_int(lig_kern_base[k]);@/ -dump_int(kern_base[k]); -dump_int(exten_base[k]); -dump_int(param_base[k]);@/ -dump_int(font_glue[k]);@/ -dump_int(bchar_label[k]); -dump_int(font_bchar[k]); -dump_int(font_false_bchar[k]);@/ -print_nl("\\font");printn_esc(font_id_text(k));print_char('='); -printn_file_name(font_name[k], font_area[k],empty_string); -if (font_size[k]!=font_dsize[k]) - {@+print(" at ");print_scaled(font_size[k]);print("pt"); - } -} - -@ @<Undump the array info for internal font number |k|@>= -{@+undump_qqqq(font_check[k]);@/ -undump_int(font_size[k]); -undump_int(font_dsize[k]); -undump(min_halfword, max_halfword, font_params[k]);@/ -undump_int(hyphen_char[k]); -undump_int(skew_char[k]);@/ -undump(0, str_ptr, font_name[k]); -undump(0, str_ptr, font_area[k]);@/ -undump(0, 255, font_bc[k]); -undump(0, 255, font_ec[k]);@/ -undump_int(char_base[k]); -undump_int(width_base[k]); -undump_int(height_base[k]);@/ -undump_int(depth_base[k]); -undump_int(italic_base[k]); -undump_int(lig_kern_base[k]);@/ -undump_int(kern_base[k]); -undump_int(exten_base[k]); -undump_int(param_base[k]);@/ -undump(min_halfword, lo_mem_max, font_glue[k]);@/ -undump(0, fmem_ptr-1, bchar_label[k]); -undump(min_quarterword, non_char, font_bchar[k]); -undump(min_quarterword, non_char, font_false_bchar[k]); -} - -@ @<Dump the hyphenation tables@>= -dump_int(hyph_count); -for (k=0; k<=hyph_size; k++) if (hyph_word[k]!=0) - {@+dump_int(k);dump_int(hyph_word[k]);dump_int(hyph_list[k]); - } -print_ln();print_int(hyph_count);print(" hyphenation exception"); -if (hyph_count!=1) print_char('s'); -if (trie_not_ready) init_trie(); -dump_int(trie_max); -for (k=0; k<=trie_max; k++) dump_hh(trie[k]); -dump_int(trie_op_ptr); -for (k=1; k<=trie_op_ptr; k++) - {@+dump_int(hyf_distance[k]); - dump_int(hyf_num[k]); - dump_int(hyf_next[k]); - } -print_nl("Hyphenation trie of length ");print_int(trie_max); -@.Hyphenation trie...@> -print(" has ");print_int(trie_op_ptr);print(" op"); -if (trie_op_ptr!=1) print_char('s'); -print(" out of ");print_int(trie_op_size); -for (k=255; k>=0; k--) if (trie_used[k] > min_quarterword) - {@+print_nl(" ");print_int(qo(trie_used[k])); - print(" for language ");print_int(k); - dump_int(k);dump_int(qo(trie_used[k])); - } - -@ Only ``nonempty'' parts of |op_start| need to be restored. - -@<Undump the hyphenation tables@>= -undump(0, hyph_size, hyph_count); -for (k=1; k<=hyph_count; k++) - {@+undump(0, hyph_size, j); - undump(0, str_ptr, hyph_word[j]); - undump(min_halfword, max_halfword, hyph_list[j]); - } -undump_size(0, trie_size,"trie size", j); -#ifdef @!INIT -trie_max=j; -#endif -for (k=0; k<=j; k++) undump_hh(trie[k]); -undump_size(0, trie_op_size,"trie op size", j); -#ifdef @!INIT -trie_op_ptr=j; -#endif -for (k=1; k<=j; k++) - {@+undump(0, 63, hyf_distance[k]); /*a |small_number|*/ - undump(0, 63, hyf_num[k]); - undump(min_quarterword, max_quarterword, hyf_next[k]); - } -#ifdef @!INIT -for (k=0; k<=255; k++) trie_used[k]=min_quarterword; -#endif -@;@/ -k=256; -while (j > 0) - {@+undump(0, k-1, k);undump(1, j, x); -#ifdef @!INIT -trie_used[k]=qi(x); -#endif -@;@/ - j=j-x;op_start[k]=qo(j); - } -#ifdef @!INIT -trie_not_ready=false -#endif - -@ We have already printed a lot of statistics, so we set |tracing_stats=0| -to prevent them from appearing again. - -@<Dump a couple more things and the closing check word@>= -dump_int(interaction);dump_int(format_ident);dump_int(69069); -tracing_stats=0 - -@ @<Undump a couple more things and the closing check word@>= -undump(batch_mode, error_stop_mode, interaction); -undump(0, str_ptr, format_ident); -undump_int(x); -if ((x!=69069)||eof(fmt_file)) goto bad_fmt - -@ @<Create the |format_ident|...@>= -selector=new_string; -print(" (preloaded format=");printn(job_name);print_char(' '); -print_int(year);print_char('.'); -print_int(month);print_char('.');print_int(day);print_char(')'); -if (interaction==batch_mode) selector=log_only; -else selector=term_and_log; -str_room(1); -format_ident=make_string(); -pack_job_name(format_extension); -while (!w_open_out(&fmt_file)) - prompt_file_name("format file name", format_extension); -print_nl("Beginning to dump on file "); -@.Beginning to dump...@> -slow_print(w_make_name_string(&fmt_file));flush_string; -print_nl("");slow_print(format_ident) - -@ @<Close the format file@>= -w_close(&fmt_file) - -@* The main program. -This is it: the part of \TeX\ that executes all those procedures we have -written. - -Well---almost. Let's leave space for a few more routines that we may -have forgotten. - -@p @<Last-minute procedures@>@; - -@ We have noted that there are two versions of \TeX82. One, called \.{INITEX}, -@.INITEX@> -has to be run first; it initializes everything from scratch, without -reading a format file, and it has the capability of dumping a format file. -The other one is called `\.{VIRTEX}'; it is a ``virgin'' program that needs -@.VIRTEX@> -to input a format file in order to get started. \.{VIRTEX} typically has -more memory capacity than \.{INITEX}, because it does not need the space -consumed by the auxiliary hyphenation tables and the numerous calls on -|primitive|, etc. - -The \.{VIRTEX} program cannot read a format file instantaneously, of course; -the best implementations therefore allow for production versions of \TeX\ that -not only avoid the loading routine for \PASCAL\ object code, they also have -a format file pre-loaded. This is impossible to do if we stick to standard -\PASCAL; but there is a simple way to fool many systems into avoiding the -initialization, as follows:\quad(1)~We declare a global integer variable -called |ready_already|. The probability is negligible that this -variable holds any particular value like 314159 when \.{VIRTEX} is first -loaded.\quad(2)~After we have read in a format file and initialized -everything, we set |ready_already=314159|.\quad(3)~Soon \.{VIRTEX} -will print `\.*', waiting for more input; and at this point we -interrupt the program and save its core image in some form that the -operating system can reload speedily.\quad(4)~When that core image is -activated, the program starts again at the beginning; but now -|ready_already==314159| and all the other global variables have -their initial values too. The former chastity has vanished! - -In other words, if we allow ourselves to test the condition -|ready_already==314159|, before |ready_already| has been -assigned a value, we can avoid the lengthy initialization. Dirty tricks -rarely pay off so handsomely. -@^dirty \PASCAL@> -@^system dependencies@> - -On systems that allow such preloading, the standard program called \.{TeX} -should be the one that has \.{plain} format preloaded, since that agrees -with {\sl The \TeX book}. Other versions, e.g., \.{AmSTeX}, should also -@:TeXbook}{\sl The \TeX book@> -@.AmSTeX@> -@.plain@> -be provided for commonly used formats. - -@<Glob...@>= -static int @!ready_already; /*a sacrifice of purity for economy*/ - -@ Now this is really it: \TeX\ starts and ends here. - -The initial test involving |ready_already| should be deleted if the -\PASCAL\ runtime system is smart enough to detect such a ``mistake.'' -@^system dependencies@> - -@p -int main(int argc, char *argv[]) {@! /*|start_here|*/ - main_init(argc, argv); /* k\TeX\ */ -history=fatal_error_stop; /*in case we quit during initialization*/ -t_open_out; /*open the terminal for output*/ -if (ready_already==314159) goto start_of_TEX; -@<Check the ``constant'' values...@>@; -if (bad > 0) - {@+wterm_ln("Ouch---my internal constants have been clobbered!" - "---case %d", bad); -@.Ouch...clobbered@> - exit(0); - } -get_strings_started(); -initialize(); /*set global variables to their starting values*/ -#ifdef @!INIT -if (iniversion) -{ init_prim(); /*call |primitive| for each primitive*/ - init_str_ptr=str_ptr;init_pool_ptr=pool_ptr;fix_date_and_time(); } -#endif -ready_already=314159; -start_of_TEX: @<Initialize the output routines@>; -@<Get the first line of input and prepare to start@>; -history=spotless; /*ready to go!*/ -hhsize=hsize; hvsize=vsize;@/ -hint_open(); main_control(); hint_close(); /*come to life*/ -final_cleanup(); /*prepare for death*/ -close_files_and_terminate(); -ready_already=0; -return 0; } - -@ Here we do whatever is needed to complete \TeX's job gracefully on the -local operating system. The code here might come into play after a fatal -error; it must therefore consist entirely of ``safe'' operations that -cannot produce error messages. For example, it would be a mistake to call -|str_room| or |make_string| at this time, because a call on |overflow| -might lead to an infinite loop. -@^system dependencies@> -(Actually there's one way to get error messages, via |prepare_mag|; -but that can't cause infinite recursion.) -@^recursion@> - -If |final_cleanup| is bypassed, this program doesn't bother to close -the input files that may still be open. - -@<Last-minute...@>= -static void close_files_and_terminate(void) -{@+int k; /*all-purpose index*/ -@<Finish the extensions@>;new_line_char=-1; -#ifdef @!STAT -if (tracing_stats > 0) @<Output statistics about this job@>;@; -#endif -wake_up_terminal; -if (log_opened) - {@+wlog_cr;a_close(&log_file);selector=selector-2; - if (selector==term_only) - {@+print_nl("Transcript written on "); -@.Transcript written...@> - slow_print(log_name);print_char('.');print_nl(""); - } - } -} - -@ The present section goes directly to the log file instead of using -|print| commands, because there's no need for these strings to take -up |str_pool| memory when a non-{\bf stat} version of \TeX\ is being used. - -@<Output statistics...@>= -if (log_opened) - {@+wlog_ln(" "); - wlog_ln("Here is how much of TeX's memory you used:"); -@.Here is how much...@> - wlog(" %d string", str_ptr-init_str_ptr); - if (str_ptr!=init_str_ptr+1) wlog( "s" ); - wlog_ln( " out of %d", max_strings-init_str_ptr);@/ - wlog_ln( " %d string characters out of %d", pool_ptr-init_pool_ptr, - pool_size-init_pool_ptr);@/ - wlog_ln(" %d words of memory out of %d", lo_mem_max-mem_min+mem_end-hi_mem_min+2,@| - mem_end+1-mem_min);@/ - wlog_ln(" %d multiletter control sequences out of %d", cs_count, hash_size);@/ - wlog(" %d words of font info for %d font", fmem_ptr, font_ptr-font_base); - if (font_ptr!=font_base+1) wlog("s"); - wlog_ln( ", out of %d for %d", font_mem_size, font_max-font_base);@/ - wlog(" %d hyphenation exception", hyph_count); - if (hyph_count!=1) wlog("s"); - wlog_ln( " out of %d", hyph_size);@/ - wlog_ln(" %di,%dn,%dp,%db,%ds stack positions out of %di,%dn,%dp,%db,%ds", - max_in_stack, max_nest_stack,@| - max_param_stack,@| - max_buf_stack+1,@| - max_save_stack+6,@| - stack_size, - nest_size, - param_size, - buf_size, - save_size ); - } - -@ We get to the |final_cleanup| routine when \.{\\end} or \.{\\dump} has -been scanned and |its_all_over|\kern-2pt. - -@<Last-minute...@>= -static void final_cleanup(void) -{@+ -int c; /*0 for \.{\\end}, 1 for \.{\\dump}*/ -c=cur_chr;if (c!=1) new_line_char=-1; -if (job_name==0) open_log_file(); -while (input_ptr > 0) - if (state==token_list) end_token_list();@+else end_file_reading(); -while (open_parens > 0) - {@+print(" )");decr(open_parens); - } -if (cur_level > level_one) - {@+print_nl("(");print_esc("end occurred "); - print("inside a group at level "); -@:end\_}{\.{(\\end occurred...)}@> - print_int(cur_level-level_one);print_char(')'); - if (eTeX_ex) show_save_groups(); - } -while (cond_ptr!=null) - {@+print_nl("(");print_esc("end occurred "); - print("when ");print_cmd_chr(if_test, cur_if); - if (if_line!=0) - {@+print(" on line ");print_int(if_line); - } - print(" was incomplete)"); - if_line=if_line_field(cond_ptr); - cur_if=subtype(cond_ptr);temp_ptr=cond_ptr; - cond_ptr=link(cond_ptr);free_node(temp_ptr, if_node_size); - } -if (history!=spotless) - if (((history==warning_issued)||(interaction < error_stop_mode))) - if (selector==term_and_log) - {@+selector=term_only; - print_nl("(see the transcript file for additional information)"); -@.see the transcript file...@> - selector=term_and_log; - } -if (c==1) - { -#ifdef @!INIT -for (c=top_mark_code; c<=split_bot_mark_code; c++) - if (cur_mark[c]!=null) delete_token_ref(cur_mark[c]); - if (last_glue!=max_halfword) delete_glue_ref(last_glue); - store_fmt_file();return; -#endif - print_nl("(\\dump is performed only by INITEX)");return; -@:dump\_}{\.{\\dump...only by INITEX}@> - } -} - -@ @<Last-minute...@>= -#ifdef @!INIT -static void init_prim(void) /*initialize all the primitives*/ -{@+no_new_control_sequence=false; -first=0; -@<Put each...@>; -no_new_control_sequence=true; -} -#endif - -@ When we begin the following code, \TeX's tables may still contain garbage; -the strings might not even be present. Thus we must proceed cautiously to get -bootstrapped in. - -But when we finish this part of the program, \TeX\ is ready to call on the -|main_control| routine to do its work. - -@<Get the first line...@>= -{@+@<Initialize the input routines@>; -@<Enable \eTeX, if requested@>@;@/ -if ((format_ident==0)||(buffer[loc]=='&')) - {@+if (format_ident!=0) initialize(); /*erase preloaded format*/ - if (!open_fmt_file()) exit(0); - if (!load_fmt_file()) - {@+w_close(&fmt_file);exit(0); - } - w_close(&fmt_file); - while ((loc < limit)&&(buffer[loc]==' ')) incr(loc); - } -if (eTeX_ex) wterm_ln("entering extended mode"); -if (end_line_char_inactive) decr(limit); -else buffer[limit]=end_line_char; -fix_date_and_time();@/ -@<Initialize the print |selector|...@>; -if ((loc < limit)&&(cat_code(buffer[loc])!=escape)) start_input(); - /*\.{\\input} assumed*/ -} - -@* Debugging. -Once \TeX\ is working, you should be able to diagnose most errors with -the \.{\\show} commands and other diagnostic features. But for the initial -stages of debugging, and for the revelation of really deep mysteries, you -can compile \TeX\ with a few more aids, including the \PASCAL\ runtime -checks and its debugger. An additional routine called |debug_help| -will also come into play when you type `\.D' after an error message; -|debug_help| also occurs just before a fatal error causes \TeX\ to succumb. -@^debugging@> -@^system dependencies@> - -The interface to |debug_help| is primitive, but it is good enough when used -with a \PASCAL\ debugger that allows you to set breakpoints and to read -variables and change their values. After getting the prompt `\.{debug \#}', you -type either a negative number (this exits |debug_help|), or zero (this -goes to a location where you can set a breakpoint, thereby entering into -dialog with the \PASCAL\ debugger), or a positive number |m| followed by -an argument |n|. The meaning of |m| and |n| will be clear from the -program below. (If |m==13|, there is an additional argument, |l|.) -@.debug \#@> - -@<Last-minute...@>= -#ifdef @!DEBUG -static void debug_help(void) /*routine to display various things*/ -{@+ -int k, @!l, @!m, @!n; -clear_terminal; - loop{@+wake_up_terminal; - print_nl("debug # (-1 to exit):");update_terminal; -@.debug \#@> - if (fscanf(term_in.f," %d",&m)<1 || - m < 0) return; - else if (m==0) - {@+goto breakpoint;@/ /*go to every declared label at least once*/ - breakpoint: m=0; /*'BREAKPOINT'*/@/ - } - else{@+fscanf(term_in.f," %d",&n); - switch (m) { - @t\4@>@<Numbered cases for |debug_help|@>@; - default:print("?"); - } - } - } -} -#endif - -@ @<Numbered cases...@>= -case 1: print_word(mem[n]);@+break; /*display |mem[n]| in all forms*/ -case 2: print_int(info(n));@+break; -case 3: print_int(link(n));@+break; -case 4: print_word(eqtb[n]);@+break; -case 5: print_word(font_info[n]);@+break; -case 6: print_word(save_stack[n]);@+break; -case 7: show_box(n);@+break; - /*show a box, abbreviated by |show_box_depth| and |show_box_breadth|*/ -case 8: {@+breadth_max=10000;depth_threshold=pool_size-pool_ptr-10; - show_node_list(n); /*show a box in its entirety*/ - } @+break; -case 9: show_token_list(n, null, 1000);@+break; -case 10: slow_print(n);@+break; -case 11: check_mem(n > 0);@+break; /*check wellformedness; print new busy locations if |n > 0|*/ -case 12: search_mem(n);@+break; /*look for pointers to |n|*/ -case 13: {@+fscanf(term_in.f," %d",&l);print_cmd_chr(n, l); - } @+break; -case 14: for (k=0; k<=n; k++) printn(buffer[k]);@+break; -case 15: {@+font_in_short_display=null_font;short_display(n); - } @+break; -case 16: panicking=!panicking;@+break; - -@* Extensions. -The program above includes a bunch of ``hooks'' that allow further -capabilities to be added without upsetting \TeX's basic structure. -Most of these hooks are concerned with ``whatsit'' nodes, which are -intended to be used for special purposes; whenever a new extension to -\TeX\ involves a new kind of whatsit node, a corresponding change needs -to be made to the routines below that deal with such nodes, -but it will usually be unnecessary to make many changes to the -other parts of this program. - -In order to demonstrate how extensions can be made, we shall treat -`\.{\\write}', `\.{\\openout}', `\.{\\closeout}', `\.{\\immediate}', -`\.{\\special}', and `\.{\\setlanguage}' as if they were extensions. -These commands are actually primitives of \TeX, and they should -appear in all implementations of the system; but let's try to imagine -that they aren't. Then the program below illustrates how a person -could add them. - -Sometimes, of course, an extension will require changes to \TeX\ itself; -no system of hooks could be complete enough for all conceivable extensions. -The features associated with `\.{\\write}' are almost all confined to the -following paragraphs, but there are small parts of the |print_ln| and -|print_char| procedures that were introduced specifically to \.{\\write} -characters. Furthermore one of the token lists recognized by the scanner -is a |write_text|; and there are a few other miscellaneous places where we -have already provided for some aspect of \.{\\write}. The goal of a \TeX\ -extender should be to minimize alterations to the standard parts of the -program, and to avoid them completely if possible. He or she should also -be quite sure that there's no easy way to accomplish the desired goals -with the standard features that \TeX\ already has. ``Think thrice before -extending,'' because that may save a lot of work, and it will also keep -incompatible extensions of \TeX\ from proliferating. -@^system dependencies@> -@^extensions to \TeX@> - -@ First let's consider the format of whatsit nodes that are used to represent -the data associated with \.{\\write} and its relatives. Recall that a whatsit -has |type==whatsit_node|, and the |subtype| is supposed to distinguish -different kinds of whatsits. Each node occupies two or more words; the -exact number is immaterial, as long as it is readily determined from the -|subtype| or other data. - -We shall introduce five |subtype| values here, corresponding to the -control sequences \.{\\openout}, \.{\\write}, \.{\\closeout}, \.{\\special}, and -\.{\\setlanguage}. The second word of I/O whatsits has a |write_stream| field -that identifies the write-stream number (0 to 15, or 16 for out-of-range and -positive, or 17 for out-of-range and negative). -In the case of \.{\\write} and \.{\\special}, there is also a field that -points to the reference count of a token list that should be sent. In the -case of \.{\\openout}, we need three words and three auxiliary subfields -to hold the string numbers for name, area, and extension. - -@d write_node_size 2 /*number of words in a write/whatsit node*/ -@d open_node_size 3 /*number of words in an open/whatsit node*/ -@d open_node 0 /*|subtype| in whatsits that represent files to \.{\\openout}*/ -@d write_node 1 /*|subtype| in whatsits that represent things to \.{\\write}*/ -@d close_node 2 /*|subtype| in whatsits that represent streams to \.{\\closeout}*/ -@d special_node 3 /*|subtype| in whatsits that represent \.{\\special} things*/ -@d language_node 4 /*|subtype| in whatsits that change the current language*/ -@d what_lang(A) link(A+1) /*language number, in the range |0 dotdot 255|*/ -@d what_lhm(A) type(A+1) /*minimum left fragment, in the range |1 dotdot 63|*/ -@d what_rhm(A) subtype(A+1) /*minimum right fragment, in the range |1 dotdot 63|*/ -@d write_tokens(A) link(A+1) /*reference count of token list to write*/ -@d write_stream(A) info(A+1) /*stream number (0 to 17)*/ -@d open_name(A) link(A+1) /*string number of file name to open*/ -@d open_area(A) info(A+2) /*string number of file area for |open_name|*/ -@d open_ext(A) link(A+2) /*string number of file extension for |open_name|*/ @# - -@d par_node 6 /*|subtype| that records the change of a parameter*/ -@d par_node_size 3 /* number of memory words in a |par_node| */ -@d par_type(A) type(A+1) /* type of parameter */ -@d int_type 0 /* type of an |int_par| node */ -@d dimen_type 1 /* type of an |dimen_par| node */ -@d glue_type 2 /* type of an |glue_par| node */ -@d par_number(A) subtype(A+1) /* the parameter number */ -@d par_value(A) mem[A+2] /* the parameter value */@# - -@d graf_node 7 /*|subtype| that records a paragraph*/ -@d graf_node_size 5 /* number of memory words in a |graf_node| */ -@d graf_penalty(A) mem[A+1].i /* the final penalty */ -@d graf_extent(A) link(A+3) /* the extent */@# -@d graf_params(A) info(A+4) /* list of parameter nodes */ -@d graf_list(A) link(A+4) /* list of content nodes */ - -@d disp_node 8 /*|subtype| that records a math display*/ -@d disp_node_size 3 /* number of memory words in a |disp_node| */ -@d display_left(A) type(A+1) /* 1=left 0=right */ -@d display_no_bs(A) subtype(A+1) /* |prev_depth==ignore_depth| */ -@d display_params(A) link(A+1) /* list of parameter nodes */ -@d display_formula(A) link(A+2) /* formula list */ -@d display_eqno(A) info(A+2) /* box with equation number */@# - -@d baseline_node 9 /*|subtype| that records a |baseline_skip| */ -@d baseline_node_size small_node_size /* This is 2; we will convert baseline nodes to glue nodes */ -@d baseline_node_no(A) mem[A+1].i /* baseline reference */@# - -@d image_node 10 /*|subtype| that records an image */ -@d image_node_size 9 /* width, depth, height, |shift_amount| like a hbox */ -@d image_width(A) width(A) /*width of image */ -@d image_height(A) height(A) /*height of image */ -@d image_depth(A) depth(A) /* depth of image==zero */ -@d image_no(A) mem[A+4].i /* the section number */ -@d image_stretch(A) mem[A+5].sc /*stretchability of image */ -@d image_shrink(A) mem[A+6].sc /*shrinkability of image */ -@d image_stretch_order(A) stretch_order(A+7) -@d image_shrink_order(A) shrink_order(A+7) -@d image_name(A) link(A+7) /*string number of file name */ -@d image_area(A) info(A+8) /*string number of file area */ -@d image_ext(A) link(A+8) /*string number of file extension */@# - -@d hpack_node 12 /* a hlist that needs to go to hpack */ -@d vpack_node 13 /* a vlist that needs to go to vpackage */ -@d pack_node_size box_node_size /* a box node up to |list_ptr|*/ -@d pack_m(A) type(A+list_offset) /* either additional or exactly */ -@d pack_limit(A) mem[(A)+1+list_offset].sc /* depth limit in |vpack| */ -@d pack_extent(A) link(A+2+list_offset) /* extent */@# - -@d hset_node 14 /* represents a hlist that needs |glue_set| */ -@d vset_node 15 /* represents a vlist that needs |glue_set| */ -@d set_node_size box_node_size /* up to |list_ptr| like a box node */ -@d set_stretch_order glue_sign -@d set_shrink_order glue_order -@d set_stretch(A) mem[(A)+1+list_offset].sc /* replaces |glue_set| */ -@d set_extent(A) pack_extent(A) /* extent */ -@d set_shrink(A) mem[(A)+3+list_offset].sc @# - -@d align_node 16 /* represents an alignment */ -@d align_node_size 4 -@d align_extent(A) link(A+2) /* the extent of the alignment */ -@d align_m(A) type(A+2) /* either additional or exactly */ -@d align_v(A) subtype(A+2) /* true if vertical */ -@d align_preamble(A) info(A+3) /* the preamble */ -@d align_list(A) link(A+3) /* the unset rows/columns */ - -@d setpage_node 17 /* represents a page template */ -@d setpage_node_size 6 -@d setpage_name(A) link(A+1) -@d setpage_number(A) type(A+1) /* the \HINT/ number */ -@d setpage_id(A) subtype(A+1) /* the \TeX\ number */ -@d setpage_priority(A) info(A+2) -@d setpage_topskip(A) link(A+2) -@d setpage_depth(A) mem[A+3].sc /* maximum depth */ -@d setpage_height(A) info(A+4) /* extended dimension number */ -@d setpage_width(A) link(A+4) /* extended dimension number */ -@d setpage_list(A) info(A+5) /* the template itself */ -@d setpage_streams(A) link(A+5) /* list of stream definitions */ - -@d setstream_node 18 /* represents a stream definition */ -@d setstream_node_size 6 -@d setstream_number(A) type(A+1) -@d setstream_insertion(A) subtype(A+1) -@d setstream_mag(A) link(A+1) /* magnification factor */ -@d setstream_prefered(A) type(A+2) -@d setstream_next(A) subtype(A+2) -@d setstream_ratio(A) link(A+2) /* split ratio */ -@d setstream_max(A) info(A+3) /* extended dimension number */ -@d setstream_width(A) link(A+3) /* extended dimension number */ -@d setstream_topskip(A) info(A+4) -@d setstream_height(A) link(A+4) -@d setstream_before(A) info(A+5) -@d setstream_after(A) link(A+5) - -@d stream_node 19 /* represents a stream insertion point */ -@d stream_node_size 2 -@d stream_number(A) type(A+1) -@d stream_insertion(A) subtype(A+1) - -@d stream_after_node 20 /* never allocated */ -@d stream_before_node 21 /* never allocated */ - -@d xdimen_node 22 -@d xdimen_node_size 4 -@d xdimen_ref_count(A) link(A) -@d xdimen_width(A) mem[A+1].sc -@d xdimen_hfactor(A) mem[A+2].sc -@d xdimen_vfactor(A) mem[A+3].sc - -@d ignore_node 23 /* ignored used to attach extra information */ -@d ignore_node_size small_node_size /* same as |disc_node| */ -@d ignore_info(A) type(A+1) -@d ignore_list(A) link(A+1) - -@d label_node 24 /* represents a link to a another location */ -@d label_node_size 2 -@d label_has_name(A) type(A+1) /* 1 for a name , 0 for a number */ -@d label_where(A) subtype(A+1) /* 1 for top, 2 for bot, 3 for mid */ -@d label_ptr(A) link(A+1) /* for a name the token list or the number */ -@d label_ref(A) link(A+1) /*alternatively the label number */ - -@d start_link_node 25 /* represents a link to a another location */ -@d end_link_node 26 /* represents a link to a another location */ -@d link_node_size 2 /* second word like a |label_node| */ - -@d outline_node 27 /* represents an outline item */ -@d outline_node_size 4 /* second word like a |label_node| */ -@d outline_ptr(A) link(A+2) /* text to be displayed */ -@d outline_depth(A) mem[A+3].i /* depth of sub items */ - - -@ The sixteen possible \.{\\write} streams are represented by the |write_file| -array. The |j|th file is open if and only if |write_open[j]==true|. The last -two streams are special; |write_open[16]| represents a stream number -greater than 15, while |write_open[17]| represents a negative stream number, -and both of these variables are always |false|. - -@<Glob...@>= -static alpha_file @!write_file[16]; -static bool @!write_open[18]; - -@ @<Set init...@>= -for (k=0; k<=17; k++) write_open[k]=false; - -@ Extensions might introduce new command codes; but it's best to use -|extension| with a modifier, whenever possible, so that |main_control| -stays the same. - -@d immediate_code 4 /*command modifier for \.{\\immediate}*/ -@d set_language_code 5 /*command modifier for \.{\\setlanguage}*/ - -@<Put each...@>= -primitive("openout", extension, open_node);@/ -@!@:open\_out\_}{\.{\\openout} primitive@> -primitive("write", extension, write_node);write_loc=cur_val;@/ -@!@:write\_}{\.{\\write} primitive@> -primitive("closeout", extension, close_node);@/ -@!@:close\_out\_}{\.{\\closeout} primitive@> -primitive("special", extension, special_node);@/ -@!@:special\_}{\.{\\special} primitive@> -primitive("immediate", extension, immediate_code);@/ -@!@:immediate\_}{\.{\\immediate} primitive@> -primitive("setlanguage", extension, set_language_code);@/ -@!@:set\_language\_}{\.{\\setlanguage} primitive@> - -primitive("@@HINT", relax, 256); /*cf.\ |relax|*/ -@!@:@@HINT\_}{\.{\\@@HINT} primitive@> - -primitive("HINTdest", extension, label_node);@/ -@!@:HINTdest\_}{\.{\\HINTdest} primitive@> - -primitive("HINTstartlink", extension, start_link_node);@/ -@!@:startlink\_}{\.{\\HINTstartlink} primitive@> - -primitive("HINTendlink", extension, end_link_node);@/ -@!@:HINTendlink\_}{\.{\\HINTendlink} primitive@> - -primitive("HINToutline", extension, outline_node);@/ -@!@:HINToutline\_}{\.{\\HINToutline} primitive@> - -primitive("image", extension, image_node);@/ -@!@:image\_}{\.{\\image} primitive@> - -primitive("setpage", extension, setpage_node);@/ -@!@:setpage\_}{\.{\\setpage} primitive@> - -primitive("stream", extension, stream_node);@/ -@!@:stream\_}{\.{\\stream} primitive@> - -primitive("setstream", extension, setstream_node);@/ -@!@:setstream\_}{\.{\\setstream} primitive@> - -primitive("before", extension, stream_before_node);@/ -@!@:before\_}{\.{\\before} primitive@> - -primitive("after", extension, stream_after_node);@/ -@!@:after\_}{\.{\\after} primitive@> - - -@ The variable |write_loc| just introduced is used to provide an -appropriate error message in case of ``runaway'' write texts. - -@<Glob...@>= -static pointer @!write_loc; /*|eqtb| address of \.{\\write}*/ - -@ @<Cases of |print_cmd_chr|...@>= -case extension: switch (chr_code) { - case open_node: print_esc("openout");@+break; - case write_node: print_esc("write");@+break; - case close_node: print_esc("closeout");@+break; - case special_node: print_esc("special");@+break; - case par_node: print("parameter");@+break; - case graf_node: print("paragraf");@+break; - case disp_node: print("display");@+break; - case baseline_node: print("baselineskip");@+break; - case hpack_node: print("hpack");@+break; - case vpack_node: print("vpack");@+break; - case hset_node: print("hset");@+break; - case vset_node: print("vset");@+break; - case image_node: print("image");@+break; - case start_link_node: print("startlink");@+break; - case end_link_node: print("endlink");@+break; - case label_node: print("dest");@+break; - case outline_node: print("outline");@+break; - case align_node: print("align");@+break; - case setpage_node: print("setpage");@+break; - case setstream_node: print("setstream");@+break; - case stream_node: print("stream");@+break; - case xdimen_node: print("xdimen");@+break; - case ignore_node: print("ignore");@+break; - case immediate_code: print_esc("immediate");@+break; - case set_language_code: print_esc("setlanguage");@+break; - default:print("[unknown extension!]"); - } @+break; - -@ When an |extension| command occurs in |main_control|, in any mode, -the |do_extension| routine is called. - -@<Cases of |main_control| that are for extensions...@>= -any_mode(extension): do_extension(); - -@ @<Declare act...@>= -@t\4@>@<Declare procedures needed in |do_extension|@>@; -static void do_extension(void) -{@+int @!k; /*all-purpose integer*/ -pointer @!p; /*all-purpose pointer*/ -switch (cur_chr) { -case open_node: @<Implement \.{\\openout}@>@;@+break; -case write_node: @<Implement \.{\\write}@>@;@+break; -case close_node: @<Implement \.{\\closeout}@>@;@+break; -case special_node: @<Implement \.{\\special}@>@;@+break; -case par_node: -case graf_node: -case disp_node: -case baseline_node: -case hpack_node: -case vpack_node: -case hset_node: -case vset_node: -case align_node: @+break;@# -case image_node:@/ -{@+ pointer p; - scan_optional_equals(); - scan_file_name(); - p=new_image_node(cur_name,cur_area,cur_ext); - loop { - if (scan_keyword("width")) - {@+scan_normal_dimen;@+image_width(p)=cur_val;} - else if (scan_keyword("height")) - {@+scan_normal_dimen;image_height(p)=cur_val; } - else if (scan_keyword("plus")) - { scan_dimen(false, true, false); - image_stretch(p)=cur_val;image_stretch_order(p)=cur_order; - } - else if (scan_keyword("minus")) - { scan_dimen(false, true, false); - image_shrink(p)=cur_val;image_shrink_order(p)=cur_order; - } - else - break; - } - hget_image_information(p); - if (abs(mode)==vmode) - append_to_vlist(p); /* image nodes have height, width, and depth like boxes */ - else - tail_append(p); - break; -} -case start_link_node: - if (abs(mode) == vmode) - fatal_error("HiTeX startlink cannot be used in vertical mode"); - else - { new_whatsit(start_link_node,link_node_size); - scan_label(tail); - } - break; -case end_link_node: - if (abs(mode) == vmode) - fatal_error("HiTeX endlink cannot be used in vertical mode"); - else - new_whatsit(end_link_node,link_node_size); - break; -case label_node: - new_whatsit(label_node,label_node_size); - scan_destination(tail); - if (scan_keyword("top")) label_where(tail)=1; - else if (scan_keyword("bot")) label_where(tail)=2; - else label_where(tail)=3; - scan_spaces(); - break; -case outline_node: - new_whatsit(outline_node,outline_node_size); - scan_label(tail); - if (scan_keyword("depth")) - { scan_int(); - outline_depth(tail)= cur_val; - } - else outline_depth(tail)=0; - outline_ptr(tail)=null; - new_save_level(outline_group);scan_left_brace(); - push_nest();mode=-hmode;prev_depth=ignore_depth;space_factor=1000; - break; -case setpage_node: -{ uint8_t n;@+ - pointer t; - scan_eight_bit_int(); n=cur_val; - if (n==0) - { print_err("Illegal redefinition of page template 0"); print_int(n); error(); break;} - scan_optional_equals(); - scan_file_name(); /* this should be improved to use |scan_name|*/ - t=new_setpage_node(n,cur_name); - loop { - if (scan_keyword("priority")) - {@+scan_eight_bit_int();setpage_priority(t)=cur_val; } - else if (scan_keyword("width")) - {@+scan_normal_dimen; setpage_width(t)=new_xdimen(cur_val,cur_hfactor,cur_vfactor); } - else if (scan_keyword("height")) - {@+scan_normal_dimen; setpage_height(t)=new_xdimen(cur_val,cur_hfactor,cur_vfactor); } - else - break; - } - new_save_level(page_group);scan_left_brace();normal_paragraph(); - push_nest();mode=-vmode;prev_depth=ignore_depth; - break; -} -case stream_node: -{ uint8_t n; - scan_eight_bit_int(); n=cur_val; - new_whatsit(stream_node,stream_node_size); - stream_insertion(tail)=n; - stream_number(tail)=hget_stream_no(n); - break; -} -case setstream_node: -{ uint8_t n; - pointer t, s; - scan_eight_bit_int(); n=cur_val; - scan_optional_equals(); - t=link(setpage_head); - if (t==null) { print_err("\\setstream without \\setpage"); error(); break;} - s=new_setstream_node(n); - link(s)=setpage_streams(t); setpage_streams(t)=s; - loop { - if (scan_keyword("prefered")) - {@+scan_eight_bit_int(); - if (cur_val!=255) - setstream_prefered(s)=hget_stream_no(cur_val); } - else if (scan_keyword("next")) - {@+scan_eight_bit_int(); - if (cur_val!=255) - setstream_next(s)=hget_stream_no(cur_val); } - else if (scan_keyword("ratio")) - {@+scan_int();setstream_ratio(s)=cur_val; } - else - break; - } - new_save_level(stream_group);scan_left_brace();normal_paragraph(); - push_nest();mode=-vmode;prev_depth=ignore_depth; - break; -} -case stream_before_node: - scan_optional_equals(); - new_save_level(stream_before_group);scan_left_brace();normal_paragraph(); - push_nest();mode=-vmode;prev_depth=ignore_depth; - break; -case stream_after_node: - scan_optional_equals(); - new_save_level(stream_after_group);scan_left_brace();normal_paragraph(); - push_nest();mode=-vmode;prev_depth=ignore_depth; - break; -case xdimen_node: -case ignore_node: @+break; -case immediate_code: @<Implement \.{\\immediate}@>@;@+break; -case set_language_code: @<Implement \.{\\setlanguage}@>@;@+break; -default:confusion("ext1"); -@:this can't happen ext1}{\quad ext1@> -} -} - -@ @<Declare procedures needed in |do_extension|@>= -void scan_spaces(void) -{ @<Get the next non-blank non-call token@>; - back_input(); -} -void scan_destination(pointer p) -{@+if (scan_keyword("name")) - { label_has_name(p)=1; - scan_toks(false,true); label_ptr(p)=def_ref; - } - else if (scan_keyword("num")) - { label_has_name(p)=0; scan_int(); label_ptr(p)=cur_val; - } - else - { print_err("`name {...}' or `num 000' expected. Inserted `num 0'."); - label_has_name(p)=0; label_ptr(p)=0; - error(); - return; - } - scan_spaces(); -} -void scan_label(pointer p) -{ if (!scan_keyword("goto")) - print_err("keyword `goto' inserted"); - scan_destination(p); -} - -@ Here is a subroutine that creates a whatsit node having a given |subtype| -and a given number of words. It initializes only the first word of the whatsit, -and appends it to the current list. - -@<Declare procedures needed in |do_extension|@>= -static void new_whatsit(small_number @!s, small_number @!w) -{@+pointer p; /*the new node*/ -p=get_node(w);type(p)=whatsit_node;subtype(p)=s; -link(tail)=p;tail=p; -} - -@ The next subroutine uses |cur_chr| to decide what sort of whatsit is -involved, and also inserts a |write_stream| number. - -@<Declare procedures needed in |do_ext...@>= -static void new_write_whatsit(small_number @!w) -{@+new_whatsit(cur_chr, w); -if (w!=write_node_size) scan_four_bit_int(); -else{@+scan_int(); - if (cur_val < 0) cur_val=17; - else if (cur_val > 15) cur_val=16; - } -write_stream(tail)=cur_val; -} - -@ @<Implement \.{\\openout}@>= -{@+new_write_whatsit(open_node_size); -scan_optional_equals();scan_file_name();@/ -open_name(tail)=cur_name;open_area(tail)=s_no(cur_area);open_ext(tail)=s_no(cur_ext); -} - -@ When `\.{\\write 12\{...\}}' appears, we scan the token list `\.{\{...\}}' -without expanding its macros; the macros will be expanded later when this -token list is rescanned. - -@<Implement \.{\\write}@>= -{@+k=cur_cs;new_write_whatsit(write_node_size);@/ -cur_cs=k;p=scan_toks(false, false);write_tokens(tail)=def_ref; -} - -@ @<Implement \.{\\closeout}@>= -{@+new_write_whatsit(write_node_size);write_tokens(tail)=null; -} - -@ When `\.{\\special\{...\}}' appears, we expand the macros in the token -list as in \.{\\xdef} and \.{\\mark}. - -@<Implement \.{\\special}@>= -{@+new_whatsit(special_node, write_node_size);write_stream(tail)=null; -p=scan_toks(false, true);write_tokens(tail)=def_ref; -} - -@ Each new type of node that appears in our data structure must be capable -of being displayed, copied, destroyed, and so on. The routines that we -need for write-oriented whatsits are somewhat like those for mark nodes; -other extensions might, of course, involve more subtlety here. - -@<Basic printing...@>= -static void print_mark(int @!p); -static void print_label(pointer @!p) -{ print("goto "); - if (label_has_name(p)) { print("name "); print_mark(label_ptr(p));} - else { print("num "); print_int(label_ptr(p));} -} - -static void print_write_whatsit(char *@!s, pointer @!p) -{@+print_esc(s); -if (write_stream(p) < 16) print_int(write_stream(p)); -else if (write_stream(p)==16) print_char('*'); -@.*\relax@> -else print_char('-'); -} - -@ @<Display the whatsit...@>= -switch (subtype(p)) { -case open_node: {@+print_write_whatsit("openout", p); - print_char('=');printn_file_name(open_name(p), open_area(p), open_ext(p)); - } @+break; -case write_node: {@+print_write_whatsit("write", p); - print_mark(write_tokens(p)); - } @+break; -case close_node: print_write_whatsit("closeout", p);@+break; -case special_node: {@+print_esc("special"); - print_mark(write_tokens(p)); - } @+break; -case language_node: {@+print_esc("setlanguage"); - print_int(what_lang(p));print(" (hyphenmin "); - print_int(what_lhm(p));print_char(','); - print_int(what_rhm(p));print_char(')'); - } @+break; -case par_node: print_esc("parameter "); - print_int(par_type(p));print_char(',');print_int(par_number(p)); - print_char(':');print_int(par_value(p).i); - break; -case graf_node: print_esc("paragraf("); - print_int(graf_penalty(p)); - print_char(')'); - node_list_display(graf_params(p)); - node_list_display(graf_list(p)); - print_xdimen(graf_extent(p)); - break; -case disp_node: print_esc("display "); - node_list_display(display_eqno(p)); - if (display_left(p)) print("left "); else print("right "); - node_list_display(display_formula(p)); - node_list_display(display_params(p)); - break; -case baseline_node: print_esc("baselineskip "); - print_baseline_skip(baseline_node_no(p)); - break; -case hset_node: case vset_node: - print_char('\\'); - print_char(subtype(p)==hset_node?'h':'v'); - print("set("); - print_scaled(height(p)); print_char('+'); - print_scaled(depth(p)); print(")x"); print_scaled(width(p)); - if (shift_amount(p)!=0) - {@+print(", shifted ");print_scaled(shift_amount(p)); - } - if (set_stretch(p)!=0) - {@+print(", stretch ");print_glue(set_stretch(p),set_stretch_order(p),"pt"); - } - if (set_shrink(p)!=0) - {@+print(", shrink ");print_glue(set_shrink(p),set_shrink_order(p),"pt"); - } - print(", extent "); print_xdimen(set_extent(p)); - node_list_display(list_ptr(p)); /*recursive call*/ - break; -case hpack_node: case vpack_node: - print_char('\\'); - print_char(subtype(p)==hpack_node?'h':'v'); - print("pack("); - print(pack_m(p)==exactly?"exactly ":"additional "); - print_xdimen(pack_extent(p)); - if (subtype(p)==vpack_node && pack_limit(p)!=max_dimen) { print(", limit "); print_scaled(pack_limit(p)); } - print_char(')'); - node_list_display(list_ptr(p)); - break; -case image_node: - print_esc("image("); - print_char('(');print_scaled(image_height(p)); - print_char('+'); print_scaled(image_depth(p)); - print(")x"); print_scaled(image_width(p)); - if (image_stretch(p)!=0) { print(" plus ");print_glue(image_stretch(p), image_stretch_order(p),"pt"); } - if (image_shrink(p)!=0) { print(" minus ");print_glue(image_shrink(p), image_shrink_order(p), "pt"); } - print(", section ");print_int(image_no(p)); - if (image_name(p)!=0) {print(", "); printn(image_name(p));} - break; -case align_node: - print_esc("align("); - print(align_m(p)==exactly?"exactly ":"additional "); - print_xdimen(align_extent(p));print_char(')'); - node_list_display(align_preamble(p)); - print_char(':'); - node_list_display(align_list(p)); - break; -case setpage_node: - print_esc("setpage");print_int(setpage_number(p));print_char(' '); printn(setpage_name(p)); - print(" priority ");print_int(setpage_priority(p)); - print(" width ");print_xdimen(setpage_width(p)); - print(" height ");print_xdimen(setpage_height(p)); - print_ln();print_current_string();print(".\\topskip=");print_spec(setpage_topskip(p),0); - print_ln();print_current_string();print(".\\maxdepth=");print_scaled(setpage_depth(p)); - node_list_display(setpage_list(p)); - node_list_display(setpage_streams(p)); - break; -case setstream_node: - print_esc("setstream");print_int(setstream_insertion(p)); - print_char('(');print_int(setstream_number(p));print_char(')'); - if (setstream_prefered(p)!=255) { print(" prefered ");print_int(setstream_prefered(p)); } - if (setstream_ratio(p)>0) { print(" ratio ");print_int(setstream_ratio(p)); } - if (setstream_next(p)!=255) { print(" next ");print_int(setstream_next(p)); } - append_char('.'); - print_ln();print_current_string();print_esc("count");print_int(setstream_insertion(p));print_char('='); - print_int(setstream_mag(p)); - print_ln();print_current_string();print_esc("dimen");print_int(setstream_insertion(p));print_char('='); - print_xdimen(setstream_max(p)); - print_ln();print_current_string();print_esc("skip");print_int(setstream_insertion(p));print_char('='); - print_spec(setstream_height(p),0); - print_ln();print_current_string();print_esc("hsize=");print_xdimen(setstream_width(p)); - print_ln();print_current_string();print_esc("topskip=");print_spec(setstream_topskip(p),0); - if (setstream_before(p)!=null) { print_ln();print_current_string();print_esc("before");node_list_display(setstream_before(p));} - if (setstream_after(p)!=null) { print_ln();print_current_string();print_esc("after");node_list_display(setstream_after(p));} - flush_char; - break; -case ignore_node: - print_esc("ignore ");print_int(ignore_info(p));print_char(':'); - node_list_display(ignore_list(p)); - break; -case start_link_node: - print_esc("startlink "); - print_label(p); - break; -case end_link_node: - print_esc("endlink "); - break; -case label_node: - print_esc("dest "); - print_label(p); - if (label_where(p)==1) print("top"); - else if (label_where(p)==2) print("bot"); - else if (label_where(p)==3) print("mid"); - else print("undefined"); - break; -case outline_node: - print_esc("outline"); - print_label(p); - print(" depth "); print_int(outline_depth(p)); - if (outline_ptr(p)==null) print("{}"); else - { print_ln();print_current_string();node_list_display(outline_ptr(p));} - break; -case stream_node: - print_esc("stream");print_int(stream_insertion(p)); - print_char('(');print_int(stream_number(p));print_char(')'); - break; -case xdimen_node: - print_esc("xdimen ");print_xdimen(p); - break; -default: print("whatsit?"); -} - -@ @<Make a partial copy of the whatsit...@>= -switch (subtype(p)) { -case open_node: {@+r=get_node(open_node_size);words=open_node_size; - } @+break; -case write_node: case special_node: {@+r=get_node(write_node_size); - add_token_ref(write_tokens(p));words=write_node_size; - } @+break; -case close_node: case language_node: {@+r=get_node(small_node_size); - words=small_node_size; - } @+break; -case par_node: -{@+r=get_node(par_node_size); - if (par_type(p)==glue_type) add_glue_ref(par_value(p).i); - words=par_node_size; - } @+break; -case graf_node: -{@+r=get_node(graf_node_size); - add_xdimen_ref(graf_extent(p)); - graf_params(r)=copy_node_list(graf_params(p)); - graf_list(r)=copy_node_list(graf_list(p)); - words=graf_node_size-1; - } @+break; -case disp_node: -{@+r=get_node(disp_node_size); - display_left(r)=display_left(p); - display_no_bs(r)=display_no_bs(p); - display_eqno(r)=copy_node_list(display_eqno(p)); - display_formula(r)=copy_node_list(display_formula(p)); - display_params(r)=copy_node_list(display_params(p)); - words=disp_node_size-2; - } @+break; -case baseline_node: -{@+r=get_node(baseline_node_size); - words=baseline_node_size; - } @+break; -case hpack_node: case vpack_node: -{@+r=get_node(pack_node_size); - pack_m(r)=pack_m(p); - list_ptr(r)=copy_node_list(list_ptr(p)); - add_xdimen_ref(pack_extent(p)); - pack_limit(r)=pack_limit(p); - words=pack_node_size-3; - } @+break; -case hset_node: case vset_node: -{@+r=get_node(set_node_size); - mem[r+8]=mem[p+8];mem[r+7]=mem[p+7];mem[r+6]=mem[p+6];mem[r+5]=mem[p+5]; /*copy the last four words*/ - add_xdimen_ref(set_extent(p)); - list_ptr(r)=copy_node_list(list_ptr(p)); /*this affects |mem[r+5]|*/ - words=5; - } @+break; -case image_node: - r=get_node(image_node_size); - words=image_node_size; - break; -case align_node: - {@+r=get_node(align_node_size); - align_preamble(r)=copy_node_list(align_preamble(p)); - align_list(r)=copy_node_list(align_list(p)); - add_xdimen_ref(align_extent(p)); - words=align_node_size-1; - } @+break; -case setpage_node: - {@+r=get_node(setpage_node_size); - add_glue_ref(setpage_topskip(p)); - add_xdimen_ref(setpage_height(p)); - add_xdimen_ref(setpage_width(p)); - setpage_list(r)=copy_node_list(setpage_list(p)); - setpage_streams(r)=copy_node_list(setpage_streams(p)); - words=setpage_node_size-1; - } @+break; -case setstream_node: - {@+r=get_node(setstream_node_size); - add_xdimen_ref(setstream_max(p)); - add_xdimen_ref(setstream_width(p)); - add_glue_ref(setstream_topskip(p)); - add_glue_ref(setstream_height(p)); - setstream_before(r)=copy_node_list(setstream_before(p)); - setstream_after(r)=copy_node_list(setstream_after(p)); - words=setstream_node_size-1; - } @+break; -case ignore_node: - r=get_node(ignore_node_size); - ignore_info(r)=ignore_info(p); - ignore_list(r)=copy_node_list(ignore_list(p)); - words=ignore_node_size-1; - break; -case start_link_node: - r=get_node(link_node_size); - if (label_has_name(p)) add_token_ref(label_ptr(p)); - words=link_node_size; - break; -case end_link_node: - r=get_node(link_node_size); - words=link_node_size; - break; -case label_node: - r=get_node(label_node_size); - if (label_has_name(p)) add_token_ref(label_ptr(p)); - words=label_node_size; - break; -case outline_node: - r=get_node(outline_node_size); - if (label_has_name(p)) add_token_ref(label_ptr(p)); - outline_ptr(r)=copy_node_list(outline_ptr(p)); - words=outline_node_size-1; - break; -case stream_node: - r=get_node(stream_node_size); - words=stream_node_size; - break; -case xdimen_node: - r=get_node(xdimen_node_size); - words=xdimen_node_size; - break; -default:confusion("ext2"); -@:this can't happen ext2}{\quad ext2@> -} - -@ @<Wipe out the whatsit...@>= -{@+switch (subtype(p)) { -case open_node: free_node(p, open_node_size);@+break; -case write_node: case special_node: {@+delete_token_ref(write_tokens(p)); - free_node(p, write_node_size);goto done; - } -case close_node: case language_node: free_node(p, small_node_size);@+break; -case par_node: - if (par_type(p)==glue_type) fast_delete_glue_ref(par_value(p).i); - free_node(p, par_node_size);@+break; -case graf_node: - delete_xdimen_ref(graf_extent(p)); - flush_node_list(graf_params(p)); - flush_node_list(graf_list(p)); - free_node(p, graf_node_size);@+break; -case disp_node: - flush_node_list(display_eqno(p)); - flush_node_list(display_formula(p)); - flush_node_list(display_params(p)); - free_node(p, disp_node_size);@+break; -case baseline_node: - free_node(p, baseline_node_size);@+break; -case hpack_node: case vpack_node: - delete_xdimen_ref(pack_extent(p)); - flush_node_list(list_ptr(p)); - free_node(p, pack_node_size);@+break; -case hset_node: case vset_node: - delete_xdimen_ref(set_extent(p)); - flush_node_list(list_ptr(p)); - free_node(p, set_node_size);@+break; -case image_node: - free_node(p,image_node_size);@+break; -case align_node: - delete_xdimen_ref(align_extent(p)); - flush_node_list(align_preamble(p)); - flush_node_list(align_list(p)); - free_node(p, align_node_size);@+break; -case setpage_node: - delete_glue_ref(setpage_topskip(p)); - delete_xdimen_ref(setpage_height(p)); - delete_xdimen_ref(setpage_width(p)); - flush_node_list(setpage_list(p)); - flush_node_list(setpage_streams(p)); - free_node(p, setpage_node_size);@+break; -case setstream_node: - delete_xdimen_ref(setstream_max(p)); - delete_xdimen_ref(setstream_width(p)); - delete_glue_ref(setstream_topskip(p)); - delete_glue_ref(setstream_height(p)); - flush_node_list(setstream_before(p)); - flush_node_list(setstream_after(p)); - free_node(p,setstream_node_size); @+break; -case ignore_node: - flush_node_list(ignore_list(p)); - free_node(p,ignore_node_size); @+break; -case start_link_node: - if (label_has_name(p)) delete_token_ref(label_ptr(p)); - free_node(p,link_node_size);@+break; -case end_link_node: - free_node(p,link_node_size);@+break; -case label_node: - if (label_has_name(p)) delete_token_ref(label_ptr(p)); - free_node(p,label_node_size);@+break; -case outline_node: - if (label_has_name(p)) delete_token_ref(label_ptr(p)); - flush_node_list(outline_ptr(p)); - free_node(p,outline_node_size);@+break; -case stream_node: - free_node(p,stream_node_size); @+break; -case xdimen_node: - free_node(p,xdimen_node_size); -default:confusion("ext3"); -@:this can't happen ext3}{\quad ext3@> -} @/ -goto done; -} - -@ @<Incorporate a whatsit node into a vbox@>=do_nothing - -@ @<Incorporate a whatsit node into an hbox@>=do_nothing - -@ @<Let |d| be the width of the whatsit |p|@>=d=0 - -@ @d adv_past(A) @+if (subtype(A)==language_node) - {@+cur_lang=what_lang(A);l_hyf=what_lhm(A);r_hyf=what_rhm(A);@+} - -@<Advance \(p)past a whatsit node in the \(l)|line_break| loop@>=@+ -adv_past(cur_p) - -@ @<Advance \(p)past a whatsit node in the \(p)pre-hyphenation loop@>=@+ -adv_past(s) - -@ @<Prepare to move whatsit |p| to the current page, then |goto contribute|@>= -goto contribute - -@ @<Process whatsit |p| in |vert_break| loop, |goto not_found|@>= -goto not_found - -@ @<Output the whatsit node |p| in a vlist@>= -out_what(p) - -@ @<Output the whatsit node |p| in an hlist@>= -out_what(p) - -@ After all this preliminary shuffling, we come finally to the routines -that actually send out the requested data. Let's do \.{\\special} first -(it's easier). - -@<Declare procedures needed in |hlist_out|, |vlist_out|@>= -static void special_out(pointer @!p) -{@+int old_setting; /*holds print |selector|*/ -int @!k; /*index into |str_pool|*/ -synch_h;synch_v;@/ -old_setting=selector;selector=new_string; -show_token_list(link(write_tokens(p)), null, pool_size-pool_ptr); -selector=old_setting; -str_room(1); -if (cur_length < 256) - {@+dvi_out(xxx1);dvi_out(cur_length); - } -else{@+dvi_out(xxx4);dvi_four(cur_length); - } -for (k=str_start[str_ptr]; k<=pool_ptr-1; k++) dvi_out(so(str_pool[k])); -pool_ptr=str_start[str_ptr]; /*erase the string*/ -} - -@ To write a token list, we must run it through \TeX's scanner, expanding -macros and \.{\\the} and \.{\\number}, etc. This might cause runaways, -if a delimited macro parameter isn't matched, and runaways would be -extremely confusing since we are calling on \TeX's scanner in the middle -of a \.{\\shipout} command. Therefore we will put a dummy control sequence as -a ``stopper,'' right after the token list. This control sequence is -artificially defined to be \.{\\outer}. -@:end\_write\_}{\.{\\endwrite}@> - -@<Initialize table...@>= -text(end_write)=s_no("endwrite");eq_level(end_write)=level_one; -eq_type(end_write)=outer_call;equiv(end_write)=null; - -@ @<Declare procedures needed in |hlist_out|, |vlist_out|@>= -static void write_out(pointer @!p) -{@+int old_setting; /*holds print |selector|*/ -int @!old_mode; /*saved |mode|*/ -small_number @!j; /*write stream number*/ -pointer @!q, @!r; /*temporary variables for list manipulation*/ -@<Expand macros in the token list and make |link(def_ref)| point to the result@>; -old_setting=selector;j=write_stream(p); -if (write_open[j]) selector=j; -else{@+ /*write to the terminal if file isn't open*/ - if ((j==17)&&(selector==term_and_log)) selector=log_only; - print_nl(""); - } -token_show(def_ref);print_ln(); -flush_list(def_ref);selector=old_setting; -} - -@ The final line of this routine is slightly subtle; at least, the author -didn't think about it until getting burnt! There is a used-up token list -@^Knuth, Donald Ervin@> -on the stack, namely the one that contained |end_write_token|. (We -insert this artificial `\.{\\endwrite}' to prevent runaways, as explained -above.) If it were not removed, and if there were numerous writes on a -single page, the stack would overflow. - -@d end_write_token cs_token_flag+end_write - -@<Expand macros in the token list and...@>= -q=get_avail();info(q)=right_brace_token+'}';@/ -r=get_avail();link(q)=r;info(r)=end_write_token;ins_list(q);@/ -begin_token_list(write_tokens(p), write_text);@/ -q=get_avail();info(q)=left_brace_token+'{';ins_list(q); - /*now we're ready to scan - `\.\{$\langle\,$token list$\,\rangle$\.{\} \\endwrite}'*/ -old_mode=mode;mode=0; - /*disable \.{\\prevdepth}, \.{\\spacefactor}, \.{\\lastskip}, \.{\\prevgraf}*/ -cur_cs=write_loc;q=scan_toks(false, true); /*expand macros, etc.*/ -get_token();@+if (cur_tok!=end_write_token) - @<Recover from an unbalanced write command@>; -mode=old_mode; -end_token_list() /*conserve stack space*/ - -@ @<Recover from an unbalanced write command@>= -{@+print_err("Unbalanced write command"); -@.Unbalanced write...@> -help2("On this page there's a \\write with fewer real {'s than }'s.",@/ -"I can't handle that very well; good luck.");error(); -@/do@+{get_token(); -}@+ while (!(cur_tok==end_write_token)); -} - -@ The |out_what| procedure takes care of outputting whatsit nodes for -|vlist_out| and |hlist_out|\kern-.3pt. - -@<Declare procedures needed in |hlist_out|, |vlist_out|@>= -void out_what(pointer @!p) -{@+small_number j; /*write stream number*/ -if (subtype(p)==open_node||subtype(p)==write_node||subtype(p)==close_node) -@<Do some work that has been queued up for \.{\\write}@>@; -} - -@ We don't implement \.{\\write} inside of leaders. (The reason is that -the number of times a leader box appears might be different in different -implementations, due to machine-dependent rounding in the glue calculations.) -@^leaders@> - -@<Do some work that has been queued up...@>= -if (!doing_leaders) - {@+j=write_stream(p); - if (subtype(p)==write_node) write_out(p); - else{@+if (write_open[j]) a_close(&write_file[j]); - if (subtype(p)==close_node) write_open[j]=false; - else if (j < 16) - {@+cur_name=open_name(p); - set_cur_area_ext(open_area(p),open_ext(p)); - if (cur_ext[0]==0) cur_ext=".tex"; - pack_cur_name; - while (!a_open_out(&write_file[j])) - prompt_file_name("output file name",".tex"); - write_open[j]=true; - } - } - } - -@ The presence of `\.{\\immediate}' causes the |do_extension| procedure -to descend to one level of recursion. Nothing happens unless \.{\\immediate} -is followed by `\.{\\openout}', `\.{\\write}', or `\.{\\closeout}'. -@^recursion@> - -@<Implement \.{\\immediate}@>= -{@+get_x_token(); -if ((cur_cmd==extension)&&(cur_chr <= close_node)) - {@+p=tail;do_extension(); /*append a whatsit node*/ - out_what(tail); /*do the action immediately*/ - flush_node_list(tail);tail=p;link(p)=null; - } -else back_input(); -} - -@ The \.{\\language} extension is somewhat different. -We need a subroutine that comes into play when a character of -a non-|clang| language is being appended to the current paragraph. - -@<Declare action...@>= -static void fix_language(void) -{@+ASCII_code @!l; /*the new current language*/ -if (language <= 0) l=0; -else if (language > 255) l=0; -else l=language; -if (l!=clang) - {@+new_whatsit(language_node, small_node_size); - what_lang(tail)=l;clang=l;@/ - what_lhm(tail)=norm_min(left_hyphen_min); - what_rhm(tail)=norm_min(right_hyphen_min); - } -} - -@ @<Implement \.{\\setlanguage}@>= -if (abs(mode)!=hmode) report_illegal_case(); -else{@+new_whatsit(language_node, small_node_size); - scan_int(); - if (cur_val <= 0) clang=0; - else if (cur_val > 255) clang=0; - else clang=cur_val; - what_lang(tail)=clang; - what_lhm(tail)=norm_min(left_hyphen_min); - what_rhm(tail)=norm_min(right_hyphen_min); - } - -@ @<Finish the extensions@>= -for (k=0; k<=15; k++) if (write_open[k]) a_close(&write_file[k]) - -@* The extended features of \eTeX. -The program has two modes of operation: (1)~In \TeX\ compatibility mode -it fully deserves the name \TeX\ and there are neither extended features -nor additional primitive commands. There are, however, a few -modifications that would be legitimate in any implementation of \TeX\ -such as, e.g., preventing inadequate results of the glue to \.{DVI} -unit conversion during |ship_out|. (2)~In extended mode there are -additional primitive commands and the extended features of \eTeX\ are -available. - -The distinction between these two modes of operation initially takes -place when a `virgin' \.{eINITEX} starts without reading a format file. -Later on the values of all \eTeX\ state variables are inherited when -\.{eVIRTEX} (or \.{eINITEX}) reads a format file. - -The code below is designed to work for cases where `$|init|\ldots|tini|$' -is a run-time switch. - -@<Enable \eTeX, if requested@>= -#ifdef @!INIT -if (iniversion && (buffer[loc]=='*'||etexp)&&str_eq_str(format_ident," (INITEX)")) - {@+no_new_control_sequence=false; - @<Generate all \eTeX\ primitives@>@; - if (buffer[loc]=='*') incr(loc); - eTeX_mode=1; /*enter extended mode*/ - @<Initialize variables for \eTeX\ extended mode@>; - } -#endif -@;@/ -if (!no_new_control_sequence) /*just entered extended mode ?*/ - no_new_control_sequence=true;@+else - -@ The \eTeX\ features available in extended mode are grouped into two -categories: (1)~Some of them are permanently enabled and have no -semantic effect as long as none of the additional primitives are -executed. (2)~The remaining \eTeX\ features are optional and can be -individually enabled and disabled. For each optional feature there is -an \eTeX\ state variable named \.{\\...state}; the feature is enabled, -resp.\ disabled by assigning a positive, resp.\ non-positive value to -that integer. - -@d eTeX_state_base (int_base+eTeX_state_code) -@d eTeX_state(A) eqtb[eTeX_state_base+A].i /*an \eTeX\ state variable*/ -@# -@d eTeX_version_code eTeX_int /*code for \.{\\eTeXversion}*/ - -@<Generate all \eTeX...@>= -primitive("lastnodetype", last_item, last_node_type_code); -@!@:last\_node\_type\_}{\.{\\lastnodetype} primitive@> -primitive("eTeXversion", last_item, eTeX_version_code); -@!@:eTeX\_version\_}{\.{\\eTeXversion} primitive@> -primitive("eTeXrevision", convert, eTeX_revision_code);@/ -@!@:eTeX\_revision\_}{\.{\\eTeXrevision} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case last_node_type_code: print_esc("lastnodetype");@+break; -case eTeX_version_code: print_esc("eTeXversion");@+break; - -@ @<Cases for fetching an integer value@>= -case eTeX_version_code: cur_val=eTeX_version;@+break; - -@ @d eTeX_ex (eTeX_mode==1) /*is this extended mode?*/ - -@<Glob...@>= -static int @!eTeX_mode; /*identifies compatibility and extended mode*/ - -@ @<Initialize table entries...@>= -eTeX_mode=0; /*initially we are in compatibility mode*/ -@<Initialize variables for \eTeX\ compatibility mode@>@; - -@ @<Dump the \eTeX\ state@>= -dump_int(eTeX_mode); -for (j=0; j<=eTeX_states-1; j++) eTeX_state(j)=0; /*disable all enhancements*/ - -@ @<Undump the \eTeX\ state@>= -undump(0, 1, eTeX_mode); -if (eTeX_ex) - {@+@<Initialize variables for \eTeX\ extended mode@>; - } -else{@+@<Initialize variables for \eTeX\ compatibility mode@>; - } - -@ The |eTeX_enabled| function simply returns its first argument as -result. This argument is |true| if an optional \eTeX\ feature is -currently enabled; otherwise, if the argument is |false|, the function -gives an error message. - -@<Declare \eTeX\ procedures for use...@>= -static bool eTeX_enabled(bool @!b, quarterword @!j, halfword @!k) -{@+if (!b) - {@+print_err("Improper ");print_cmd_chr(j, k); - help1("Sorry, this optional e-TeX feature has been disabled.");error(); - } -return b; -} - -@ First we implement the additional \eTeX\ parameters in the table of -equivalents. - -@<Generate all \eTeX...@>= -primitive("everyeof", assign_toks, every_eof_loc); -@!@:every\_eof\_}{\.{\\everyeof} primitive@> -primitive("tracingassigns", assign_int, int_base+tracing_assigns_code);@/ -@!@:tracing\_assigns\_}{\.{\\tracingassigns} primitive@> -primitive("tracinggroups", assign_int, int_base+tracing_groups_code);@/ -@!@:tracing\_groups\_}{\.{\\tracinggroups} primitive@> -primitive("tracingifs", assign_int, int_base+tracing_ifs_code);@/ -@!@:tracing\_ifs\_}{\.{\\tracingifs} primitive@> -primitive("tracingscantokens", assign_int, int_base+tracing_scan_tokens_code);@/ -@!@:tracing\_scan\_tokens\_}{\.{\\tracingscantokens} primitive@> -primitive("tracingnesting", assign_int, int_base+tracing_nesting_code);@/ -@!@:tracing\_nesting\_}{\.{\\tracingnesting} primitive@> - -@ @d every_eof equiv(every_eof_loc) - -@<Cases of |assign_toks| for |print_cmd_chr|@>= -case every_eof_loc: print_esc("everyeof");@+break; - -@ @<Cases for |print_param|@>= -case tracing_assigns_code: print_esc("tracingassigns");@+break; -case tracing_groups_code: print_esc("tracinggroups");@+break; -case tracing_ifs_code: print_esc("tracingifs");@+break; -case tracing_scan_tokens_code: print_esc("tracingscantokens");@+break; -case tracing_nesting_code: print_esc("tracingnesting");@+break; - -@ In order to handle \.{\\everyeof} we need an array |eof_seen| of -boolean variables. - -@<Glob...@>= -static bool @!eof_seen0[max_in_open], *const @!eof_seen = @!eof_seen0-1; /*has eof been seen?*/ - -@ The |print_group| procedure prints the current level of grouping and -the name corresponding to |cur_group|. - -@<Declare \eTeX\ procedures for tr...@>= -static void print_group(bool @!e) -{@+ -switch (cur_group) { - case bottom_level: {@+print("bottom level");return; - } - case simple_group: case semi_simple_group: - {@+if (cur_group==semi_simple_group) print("semi "); - print("simple"); - } @+break; - case hbox_group: case adjusted_hbox_group: - {@+if (cur_group==adjusted_hbox_group) print("adjusted "); - print("hbox"); - } @+break; - case vbox_group: print("vbox");@+break; - case vtop_group: print("vtop");@+break; - case align_group: case no_align_group: - {@+if (cur_group==no_align_group) print("no "); - print("align"); - } @+break; - case output_group: print("output");@+break; - case disc_group: print("disc");@+break; - case insert_group: print("insert");@+break; - case vcenter_group: print("vcenter");@+break; - case math_group: case math_choice_group: case math_shift_group: case math_left_group: - {@+print("math"); - if (cur_group==math_choice_group) print(" choice"); - else if (cur_group==math_shift_group) print(" shift"); - else if (cur_group==math_left_group) print(" left"); - } - } /*there are no other cases*/ -print(" group (level ");print_int(qo(cur_level));print_char(')'); -if (saved(-1)!=0) - {@+if (e) print(" entered at line ");else print(" at line "); - print_int(saved(-1)); - } -} - -@ The |group_trace| procedure is called when a new level of grouping -begins (|e==false|) or ends (|e==true|) with |saved(-1)| containing the -line number. - -@<Declare \eTeX\ procedures for tr...@>= -#ifdef @!STAT -static void group_trace(bool @!e) -{@+begin_diagnostic();print_char('{'); -if (e) print("leaving ");else print("entering "); -print_group(e);print_char('}');end_diagnostic(false); -} -#endif - -@ The \.{\\currentgrouplevel} and \.{\\currentgrouptype} commands return -the current level of grouping and the type of the current group -respectively. - -@d current_group_level_code (eTeX_int+1) /*code for \.{\\currentgrouplevel}*/ -@d current_group_type_code (eTeX_int+2) /*code for \.{\\currentgrouptype}*/ - -@<Generate all \eTeX...@>= -primitive("currentgrouplevel", last_item, current_group_level_code); -@!@:current\_group\_level\_}{\.{\\currentgrouplevel} primitive@> -primitive("currentgrouptype", last_item, current_group_type_code); -@!@:current\_group\_type\_}{\.{\\currentgrouptype} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case current_group_level_code: print_esc("currentgrouplevel");@+break; -case current_group_type_code: print_esc("currentgrouptype");@+break; - -@ @<Cases for fetching an integer value@>= -case current_group_level_code: cur_val=cur_level-level_one;@+break; -case current_group_type_code: cur_val=cur_group;@+break; - -@ The \.{\\currentiflevel}, \.{\\currentiftype}, and -\.{\\currentifbranch} commands return the current level of conditionals -and the type and branch of the current conditional. - -@d current_if_level_code (eTeX_int+3) /*code for \.{\\currentiflevel}*/ -@d current_if_type_code (eTeX_int+4) /*code for \.{\\currentiftype}*/ -@d current_if_branch_code (eTeX_int+5) /*code for \.{\\currentifbranch}*/ - -@<Generate all \eTeX...@>= -primitive("currentiflevel", last_item, current_if_level_code); -@!@:current\_if\_level\_}{\.{\\currentiflevel} primitive@> -primitive("currentiftype", last_item, current_if_type_code); -@!@:current\_if\_type\_}{\.{\\currentiftype} primitive@> -primitive("currentifbranch", last_item, current_if_branch_code); -@!@:current\_if\_branch\_}{\.{\\currentifbranch} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case current_if_level_code: print_esc("currentiflevel");@+break; -case current_if_type_code: print_esc("currentiftype");@+break; -case current_if_branch_code: print_esc("currentifbranch");@+break; - -@ @<Cases for fetching an integer value@>= -case current_if_level_code: {@+q=cond_ptr;cur_val=0; - while (q!=null) - {@+incr(cur_val);q=link(q); - } - } @+break; -case current_if_type_code: if (cond_ptr==null) cur_val=0; - else if (cur_if < unless_code) cur_val=cur_if+1; - else cur_val=-(cur_if-unless_code+1);@+break; -case current_if_branch_code: - if ((if_limit==or_code)||(if_limit==else_code)) cur_val=1; - else if (if_limit==fi_code) cur_val=-1; - else cur_val=0;@+break; - -@ The \.{\\fontcharwd}, \.{\\fontcharht}, \.{\\fontchardp}, and -\.{\\fontcharic} commands return information about a character in a -font. - -@d font_char_wd_code eTeX_dim /*code for \.{\\fontcharwd}*/ -@d font_char_ht_code (eTeX_dim+1) /*code for \.{\\fontcharht}*/ -@d font_char_dp_code (eTeX_dim+2) /*code for \.{\\fontchardp}*/ -@d font_char_ic_code (eTeX_dim+3) /*code for \.{\\fontcharic}*/ - -@<Generate all \eTeX...@>= -primitive("fontcharwd", last_item, font_char_wd_code); -@!@:font\_char\_wd\_}{\.{\\fontcharwd} primitive@> -primitive("fontcharht", last_item, font_char_ht_code); -@!@:font\_char\_ht\_}{\.{\\fontcharht} primitive@> -primitive("fontchardp", last_item, font_char_dp_code); -@!@:font\_char\_dp\_}{\.{\\fontchardp} primitive@> -primitive("fontcharic", last_item, font_char_ic_code); -@!@:font\_char\_ic\_}{\.{\\fontcharic} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case font_char_wd_code: print_esc("fontcharwd");@+break; -case font_char_ht_code: print_esc("fontcharht");@+break; -case font_char_dp_code: print_esc("fontchardp");@+break; -case font_char_ic_code: print_esc("fontcharic");@+break; - -@ @<Cases for fetching a dimension value@>= -case font_char_wd_code: -case font_char_ht_code: -case font_char_dp_code: -case font_char_ic_code: {@+scan_font_ident();q=cur_val;scan_char_num(); - if ((font_bc[q] <= cur_val)&&(font_ec[q] >= cur_val)) - {@+i=char_info(q, qi(cur_val)); - switch (m) { - case font_char_wd_code: cur_val=char_width(q, i);@+break; - case font_char_ht_code: cur_val=char_height(q, height_depth(i));@+break; - case font_char_dp_code: cur_val=char_depth(q, height_depth(i));@+break; - case font_char_ic_code: cur_val=char_italic(q, i); - } /*there are no other cases*/ - } - else cur_val=0; - } @+break; - -@ The \.{\\parshapedimen}, \.{\\parshapeindent}, and \.{\\parshapelength} -commands return the indent and length parameters of the current -\.{\\parshape} specification. - -@d par_shape_length_code (eTeX_dim+4) /*code for \.{\\parshapelength}*/ -@d par_shape_indent_code (eTeX_dim+5) /*code for \.{\\parshapeindent}*/ -@d par_shape_dimen_code (eTeX_dim+6) /*code for \.{\\parshapedimen}*/ - -@<Generate all \eTeX...@>= -primitive("parshapelength", last_item, par_shape_length_code); -@!@:par\_shape\_length\_}{\.{\\parshapelength} primitive@> -primitive("parshapeindent", last_item, par_shape_indent_code); -@!@:par\_shape\_indent\_}{\.{\\parshapeindent} primitive@> -primitive("parshapedimen", last_item, par_shape_dimen_code); -@!@:par\_shape\_dimen\_}{\.{\\parshapedimen} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case par_shape_length_code: print_esc("parshapelength");@+break; -case par_shape_indent_code: print_esc("parshapeindent");@+break; -case par_shape_dimen_code: print_esc("parshapedimen");@+break; - -@ @<Cases for fetching a dimension value@>= -case par_shape_length_code: -case par_shape_indent_code: -case par_shape_dimen_code: {@+q=cur_chr-par_shape_length_code;scan_int(); - if ((par_shape_ptr==null)||(cur_val <= 0)) cur_val=0; - else{@+if (q==2) - {@+q=cur_val%2;cur_val=(cur_val+q)/2; - } - if (cur_val > info(par_shape_ptr)) cur_val=info(par_shape_ptr); - cur_val=mem[par_shape_ptr+2*cur_val-q].sc; - } - cur_val_level=dimen_val; - } @+break; - -@ The \.{\\showgroups} command displays all currently active grouping -levels. - -@d show_groups 4 /* \.{\\showgroups} */ - -@<Generate all \eTeX...@>= -primitive("showgroups", xray, show_groups); -@!@:show\_groups\_}{\.{\\showgroups} primitive@> - -@ @<Cases of |xray| for |print_cmd_chr|@>= -case show_groups: print_esc("showgroups");@+break; - -@ @<Cases for |show_whatever|@>= -case show_groups: {@+begin_diagnostic();show_save_groups(); - } @+break; - -@ @<Types...@>= -typedef int32_t save_pointer; /*index into |save_stack|*/ - -@ The modifications of \TeX\ required for the display produced by the -|show_save_groups| procedure were first discussed by Donald~E. Knuth in -{\sl TUGboat\/} {\bf 11}, 165--170 and 499--511, 1990. -@^Knuth, Donald Ervin@> - -In order to understand a group type we also have to know its mode. -Since unrestricted horizontal modes are not associated with grouping, -they are skipped when traversing the semantic nest. - -@<Declare \eTeX\ procedures for use...@>= -static void show_save_groups(void) -{@+ -int p; /*index into |nest|*/ -int @!m; /*mode*/ -save_pointer @!v; /*saved value of |save_ptr|*/ -quarterword @!l; /*saved value of |cur_level|*/ -group_code @!c; /*saved value of |cur_group|*/ -int @!a; /*to keep track of alignments*/ -int @!i; -quarterword @!j; -char *@!s; -p=nest_ptr;nest[p]=cur_list; /*put the top level into the array*/ -v=save_ptr;l=cur_level;c=cur_group; -save_ptr=cur_boundary;decr(cur_level);@/ -a=1; -print_nl("");print_ln(); -loop@+{@+print_nl("### ");print_group(true); - if (cur_group==bottom_level) goto done; - @/do@+{m=nest[p].mode_field; - if (p > 0) decr(p);else m=vmode; - }@+ while (!(m!=hmode)); - print(" ("); - switch (cur_group) { - case simple_group: {@+incr(p);goto found2; - } - case hbox_group: case adjusted_hbox_group: s="hbox";@+break; - case vbox_group: s="vbox";@+break; - case vtop_group: s="vtop";@+break; - case align_group: if (a==0) - {@+if (m==-vmode) s="halign";else s="valign"; - a=1;goto found1; - } - else{@+if (a==1) print("align entry");else print_esc("cr"); - if (p >= a) p=p-a; - a=0;goto found; - } @+break; - case no_align_group: - {@+incr(p);a=-1;print_esc("noalign");goto found2; - } - case output_group: - {@+print_esc("output");goto found; - } - case math_group: goto found2; - case disc_group: case math_choice_group: - {@+if (cur_group==disc_group) print_esc("discretionary"); - else print_esc("mathchoice"); - for (i=1; i<=3; i++) if (i <= saved(-2)) print("{}"); - goto found2; - } - case insert_group: - {@+if (saved(-2)==255) print_esc("vadjust"); - else{@+print_esc("insert");print_int(saved(-2)); - } - goto found2; - } - case vcenter_group: {@+s="vcenter";goto found1; - } - case semi_simple_group: {@+incr(p);print_esc("begingroup");goto found; - } - case math_shift_group: - {@+if (m==mmode) print_char('$'); - else if (nest[p].mode_field==mmode) - {@+print_cmd_chr(eq_no, saved(-2));goto found; - } - print_char('$');goto found; - } - case math_left_group: - {@+if (type(nest[p+1].eTeX_aux_field)==left_noad) print_esc("left"); - else print_esc("middle"); - goto found; - } - } /*there are no other cases*/ - @<Show the box context@>; - found1: print_esc(s);@<Show the box packaging info@>; - found2: print_char('{'); - found: print_char(')');decr(cur_level); - cur_group=save_level(save_ptr);save_ptr=save_index(save_ptr); - } -done: save_ptr=v;cur_level=l;cur_group=c; -} - -@ @<Show the box packaging info@>= -if (saved(-2)!=0) - {@+print_char(' '); - if (saved(-3)==exactly) print("to");else print("spread"); - print_scaled(saved(-2));print("pt"); - } - -@ @<Show the box context@>= -i=saved(-4); -if (i!=0) - if (i < box_flag) - {@+if (abs(nest[p].mode_field)==vmode) j=hmove;else j=vmove; - if (i > 0) print_cmd_chr(j, 0);else print_cmd_chr(j, 1); - print_scaled(abs(i));print("pt"); - } - else if (i < ship_out_flag) - {@+if (i >= global_box_flag) - {@+print_esc("global");i=i-(global_box_flag-box_flag); - } - print_esc("setbox");print_int(i-box_flag);print_char('='); - } - else print_cmd_chr(leader_ship, i-(leader_flag-a_leaders)) - -@ The |scan_general_text| procedure is much like |scan_toks(false, false)|, -but will be invoked via |expand|, i.e., recursively. -@^recursion@> - -@<Declare \eTeX\ procedures for sc...@>= -static void scan_general_text(void); - -@ The token list (balanced text) created by |scan_general_text| begins -at |link(temp_head)| and ends at |cur_val|. (If |cur_val==temp_head|, -the list is empty.) - -@<Declare \eTeX\ procedures for tok...@>= -static void scan_general_text(void) -{@+ -int s; /*to save |scanner_status|*/ -pointer @!w; /*to save |warning_index|*/ -pointer @!d; /*to save |def_ref|*/ -pointer @!p; /*tail of the token list being built*/ -pointer @!q; /*new node being added to the token list via |store_new_token|*/ -halfword @!unbalance; /*number of unmatched left braces*/ -s=scanner_status;w=warning_index;d=def_ref; -scanner_status=absorbing;warning_index=cur_cs; -def_ref=get_avail();token_ref_count(def_ref)=null;p=def_ref; -scan_left_brace(); /*remove the compulsory left brace*/ -unbalance=1; -loop@+{@+get_token(); - if (cur_tok < right_brace_limit) - if (cur_cmd < right_brace) incr(unbalance); - else{@+decr(unbalance); - if (unbalance==0) goto found; - } - store_new_token(cur_tok); - } -found: q=link(def_ref);free_avail(def_ref); /*discard reference count*/ -if (q==null) cur_val=temp_head;@+else cur_val=p; -link(temp_head)=q; -scanner_status=s;warning_index=w;def_ref=d; -} - -@ The \.{\\showtokens} command displays a token list. - -@d show_tokens 5 /* \.{\\showtokens} , must be odd! */ - -@<Generate all \eTeX...@>= -primitive("showtokens", xray, show_tokens); -@!@:show\_tokens\_}{\.{\\showtokens} primitive@> - -@ @<Cases of |xray| for |print_cmd_chr|@>= -case show_tokens: print_esc("showtokens");@+break; - -@ The \.{\\unexpanded} primitive prevents expansion of tokens much as -the result from \.{\\the} applied to a token variable. The -\.{\\detokenize} primitive converts a token list into a list of -character tokens much as if the token list were written to a file. We -use the fact that the command modifiers for \.{\\unexpanded} and -\.{\\detokenize} are odd whereas those for \.{\\the} and \.{\\showthe} -are even. - -@<Generate all \eTeX...@>= -primitive("unexpanded", the, 1);@/ -@!@:unexpanded\_}{\.{\\unexpanded} primitive@> -primitive("detokenize", the, show_tokens);@/ -@!@:detokenize\_}{\.{\\detokenize} primitive@> - -@ @<Cases of |the| for |print_cmd_chr|@>=; -else if (chr_code==1) print_esc("unexpanded"); -else print_esc("detokenize") - -@ @<Handle \.{\\unexpanded} or \.{\\detokenize} and |return|@>= -if (odd(cur_chr)) - {@+c=cur_chr;scan_general_text(); - if (c==1) return cur_val; - else{@+old_setting=selector;selector=new_string;b=pool_ptr; - p=get_avail();link(p)=link(temp_head); - token_show(p);flush_list(p); - selector=old_setting;return str_toks(b); - } - - } - -@ The \.{\\showifs} command displays all currently active conditionals. - -@d show_ifs 6 /* \.{\\showifs} */ - -@<Generate all \eTeX...@>= -primitive("showifs", xray, show_ifs); -@!@:show\_ifs\_}{\.{\\showifs} primitive@> - -@ @<Cases of |xray| for |print_cmd_chr|@>= -case show_ifs: print_esc("showifs");@+break; - -@ @d print_if_line(A) if (A!=0) - {@+print(" entered on line ");print_int(A); - } - -@<Cases for |show_whatever|@>= -case show_ifs: {@+begin_diagnostic();print_nl("");print_ln(); - if (cond_ptr==null) - {@+print_nl("### ");print("no active conditionals"); - } - else{@+p=cond_ptr;n=0; - @/do@+{incr(n);p=link(p);@+}@+ while (!(p==null)); - p=cond_ptr;t=cur_if;l=if_line;m=if_limit; - @/do@+{print_nl("### level ");print_int(n);print(": "); - print_cmd_chr(if_test, t); - if (m==fi_code) print_esc("else"); - print_if_line(l); - decr(n);t=subtype(p);l=if_line_field(p);m=type(p);p=link(p); - }@+ while (!(p==null)); - } - } @+break; - -@ The \.{\\interactionmode} primitive allows to query and set the -interaction mode. - -@<Generate all \eTeX...@>= -primitive("interactionmode", set_page_int, 2); -@!@:interaction\_mode\_}{\.{\\interactionmode} primitive@> - -@ @<Cases of |set_page_int| for |print_cmd_chr|@>=; -else if (chr_code==2) print_esc("interactionmode") - -@ @<Cases for `Fetch the |dead_cycles| or the |insert_penalties|'@>=; -else if (m==2) cur_val=interaction - -@ @<Declare \eTeX\ procedures for use...@>= -static void new_interaction(void); - -@ @<Cases for |alter_integer|@>=; -else if (c==2) - {@+if ((cur_val < batch_mode)||(cur_val > error_stop_mode)) - {@+print_err("Bad interaction mode"); -@.Bad interaction mode@> - help2("Modes are 0=batch, 1=nonstop, 2=scroll, and",@/ - "3=errorstop. Proceed, and I'll ignore this case."); - int_error(cur_val); - } - else{@+cur_chr=cur_val;new_interaction(); - } - } - -@ The |middle| feature of \eTeX\ allows one ore several \.{\\middle} -delimiters to appear between \.{\\left} and \.{\\right}. - -@<Generate all \eTeX...@>= -primitive("middle", left_right, middle_noad); -@!@:middle\_}{\.{\\middle} primitive@> - -@ @<Cases of |left_right| for |print_cmd_chr|@>=; -else if (chr_code==middle_noad) print_esc("middle") - -@ The |scan_tokens| feature of \eTeX\ defines the \.{\\scantokens} -primitive. - -@<Generate all \eTeX...@>= -primitive("scantokens", input, 2); -@!@:scan\_tokens\_}{\.{\\scantokens} primitive@> - -@ @<Cases of |input| for |print_cmd_chr|@>=; -else if (chr_code==2) print_esc("scantokens") - -@ @<Cases for |input|@>=; -else if (cur_chr==2) pseudo_start() - -@ The global variable |pseudo_files| is used to maintain a stack of -pseudo files. The |info| field of each pseudo file points to a linked -list of variable size nodes representing lines not yet processed: the -|info| field of the first word contains the size of this node, all the -following words contain ASCII codes. - -@<Glob...@>= -static pointer @!pseudo_files; /*stack of pseudo files*/ - -@ @<Set init...@>= -pseudo_files=null; - -@ The |pseudo_start| procedure initiates reading from a pseudo file. - -@<Declare \eTeX\ procedures for ex...@>= -static void pseudo_start(void); - -@ @<Declare \eTeX\ procedures for tok...@>= -static void pseudo_start(void) -{@+int old_setting; /*holds |selector| setting*/ -str_number @!s; /*string to be converted into a pseudo file*/ -pool_pointer @!l, @!m; /*indices into |str_pool|*/ -pointer @!p, @!q, @!r; /*for list construction*/ -four_quarters @!w; /*four ASCII codes*/ -int @!nl, @!sz; -scan_general_text(); -old_setting=selector;selector=new_string; -token_show(temp_head);selector=old_setting; -flush_list(link(temp_head)); -str_room(1);s=make_string(); -@<Convert string |s| into a new pseudo file@>; -flush_string; -@<Initiate input from new pseudo file@>; -} - -@ @<Convert string |s| into a new pseudo file@>= -str_pool[pool_ptr]=si(' ');l=str_start[s]; -nl=si(new_line_char); -p=get_avail();q=p; -while (l < pool_ptr) - {@+m=l; - while ((l < pool_ptr)&&(str_pool[l]!=nl)) incr(l); - sz=(l-m+7)/4; - if (sz==1) sz=2; - r=get_node(sz);link(q)=r;q=r;info(q)=hi(sz); - while (sz > 2) - {@+decr(sz);incr(r); - w.b0=qi(so(str_pool[m]));w.b1=qi(so(str_pool[m+1])); - w.b2=qi(so(str_pool[m+2]));w.b3=qi(so(str_pool[m+3])); - mem[r].qqqq=w;m=m+4; - } - w.b0=qi(' ');w.b1=qi(' ');w.b2=qi(' ');w.b3=qi(' '); - if (l > m) - {@+w.b0=qi(so(str_pool[m])); - if (l > m+1) - {@+w.b1=qi(so(str_pool[m+1])); - if (l > m+2) - {@+w.b2=qi(so(str_pool[m+2])); - if (l > m+3) w.b3=qi(so(str_pool[m+3])); - } - } - } - mem[r+1].qqqq=w; - if (str_pool[l]==nl) incr(l); - } -info(p)=link(p);link(p)=pseudo_files;pseudo_files=p - -@ @<Initiate input from new pseudo file@>= -begin_file_reading(); /*set up |cur_file| and new level of input*/ -line=0;limit=start;loc=limit+1; /*force line read*/ -if (tracing_scan_tokens > 0) - {@+if (term_offset > max_print_line-3) print_ln(); - else if ((term_offset > 0)||(file_offset > 0)) print_char(' '); - name=19;print("( ");incr(open_parens);update_terminal; - } -else name=18 - -@ Here we read a line from the current pseudo file into |buffer|. - -@<Declare \eTeX\ procedures for tr...@>= -static bool pseudo_input(void) /*inputs the next line or returns |false|*/ -{@+pointer p; /*current line from pseudo file*/ -int @!sz; /*size of node |p|*/ -four_quarters @!w; /*four ASCII codes*/ -int @!r; /*loop index*/ -last=first; /*cf.\ Matthew 19\thinspace:\thinspace30*/ -p=info(pseudo_files); -if (p==null) return false; -else{@+info(pseudo_files)=link(p);sz=ho(info(p)); - if (4*sz-3 >= buf_size-last) - @<Report overflow of the input buffer, and abort@>; - last=first; - for (r=p+1; r<=p+sz-1; r++) - {@+w=mem[r].qqqq; - buffer[last]=w.b0;buffer[last+1]=w.b1; - buffer[last+2]=w.b2;buffer[last+3]=w.b3; - last=last+4; - } - if (last >= max_buf_stack) max_buf_stack=last+1; - while ((last > first)&&(buffer[last-1]==' ')) decr(last); - free_node(p, sz); - return true; - } -} - -@ When we are done with a pseudo file we `close' it. - -@<Declare \eTeX\ procedures for tr...@>= -static void pseudo_close(void) /*close the top level pseudo file*/ -{@+pointer p, @!q; -p=link(pseudo_files);q=info(pseudo_files); -free_avail(pseudo_files);pseudo_files=p; -while (q!=null) - {@+p=q;q=link(p);free_node(p, ho(info(p))); - } -} - -@ @<Dump the \eTeX\ state@>= -while (pseudo_files!=null) pseudo_close(); /*flush pseudo files*/ - -@ @<Generate all \eTeX...@>= -primitive("readline", read_to_cs, 1);@/ -@!@:read\_line\_}{\.{\\readline} primitive@> - -@ @<Cases of |read| for |print_cmd_chr|@>=; -else print_esc("readline") - -@ @<Handle \.{\\readline} and |goto done|@>= -if (j==1) - {@+while (loc <= limit) /*current line not yet finished*/ - {@+cur_chr=buffer[loc];incr(loc); - if (cur_chr==' ') cur_tok=space_token; - @+else cur_tok=cur_chr+other_token; - store_new_token(cur_tok); - } - goto done; - } - -@ Here we define the additional conditionals of \eTeX\ as well as the -\.{\\unless} prefix. - -@d if_def_code 17 /* `\.{\\ifdefined}' */ -@d if_cs_code 18 /* `\.{\\ifcsname}' */ -@d if_font_char_code 19 /* `\.{\\iffontchar}' */ - -@<Generate all \eTeX...@>= -primitive("unless", expand_after, 1);@/ -@!@:unless\_}{\.{\\unless} primitive@> -primitive("ifdefined", if_test, if_def_code); -@!@:if\_defined\_}{\.{\\ifdefined} primitive@> -primitive("ifcsname", if_test, if_cs_code); -@!@:if\_cs\_name\_}{\.{\\ifcsname} primitive@> -primitive("iffontchar", if_test, if_font_char_code); -@!@:if\_font\_char\_}{\.{\\iffontchar} primitive@> - -@ @<Cases of |expandafter| for |print_cmd_chr|@>=; -else print_esc("unless") - -@ @<Cases of |if_test| for |print_cmd_chr|@>= -case if_def_code: print_esc("ifdefined");@+break; -case if_cs_code: print_esc("ifcsname");@+break; -case if_font_char_code: print_esc("iffontchar");@+break; - -@ The result of a boolean condition is reversed when the conditional is -preceded by \.{\\unless}. - -@<Negate a boolean conditional and |goto reswitch|@>= -{@+get_token(); -if ((cur_cmd==if_test)&&(cur_chr!=if_case_code)) - {@+cur_chr=cur_chr+unless_code;goto reswitch; - } -print_err("You can't use `");print_esc("unless");print("' before `"); -@.You can't use \\unless...@> -print_cmd_chr(cur_cmd, cur_chr);print_char('\''); -help1("Continue, and I'll forget that it ever happened."); -back_error(); -} - -@ The conditional \.{\\ifdefined} tests if a control sequence is -defined. - -We need to reset |scanner_status|, since \.{\\outer} control sequences -are allowed, but we might be scanning a macro definition or preamble. - -@<Cases for |conditional|@>= -case if_def_code: {@+save_scanner_status=scanner_status; - scanner_status=normal; - get_next();b=(cur_cmd!=undefined_cs); - scanner_status=save_scanner_status; - } @+break; - -@ The conditional \.{\\ifcsname} is equivalent to \.{\{\\expandafter} -\.{\}\\expandafter} \.{\\ifdefined} \.{\\csname}, except that no new -control sequence will be entered into the hash table (once all tokens -preceding the mandatory \.{\\endcsname} have been expanded). - -@<Cases for |conditional|@>= -case if_cs_code: {@+n=get_avail();p=n; /*head of the list of characters*/ - @/do@+{get_x_token(); - if (cur_cs==0) store_new_token(cur_tok); - }@+ while (!(cur_cs!=0)); - if (cur_cmd!=end_cs_name) @<Complain about missing \.{\\endcsname}@>; - @<Look up the characters of list |n| in the hash table, and set |cur_cs|@>; - flush_list(n); - b=(eq_type(cur_cs)!=undefined_cs); - } @+break; - -@ @<Look up the characters of list |n| in the hash table...@>= -m=first;p=link(n); -while (p!=null) - {@+if (m >= max_buf_stack) - {@+max_buf_stack=m+1; - if (max_buf_stack==buf_size) - overflow("buffer size", buf_size); -@:TeX capacity exceeded buffer size}{\quad buffer size@> - } - buffer[m]=info(p)%0400;incr(m);p=link(p); - } -if (m==first) cur_cs=null_cs; /*the list is empty*/ -else if (m > first+1) - cur_cs=id_lookup(first, m-first); /*|no_new_control_sequence| is |true|*/ -else cur_cs=single_base+buffer[first] /*the list has length one*/ - -@ The conditional \.{\\iffontchar} tests the existence of a character in -a font. - -@<Cases for |conditional|@>= -case if_font_char_code: {@+scan_font_ident();n=cur_val;scan_char_num(); - if ((font_bc[n] <= cur_val)&&(font_ec[n] >= cur_val)) - b=char_exists(char_info(n, qi(cur_val))); - else b=false; - } @+break; - -@ The |protected| feature of \eTeX\ defines the \.{\\protected} prefix -command for macro definitions. Such macros are protected against -expansions when lists of expanded tokens are built, e.g., for \.{\\edef} -or during \.{\\write}. - -@<Generate all \eTeX...@>= -primitive("protected", prefix, 8); -@!@:protected\_}{\.{\\protected} primitive@> - -@ @<Cases of |prefix| for |print_cmd_chr|@>=; -else if (chr_code==8) print_esc("protected") - -@ The |get_x_or_protected| procedure is like |get_x_token| except that -protected macros are not expanded. - -@<Declare \eTeX\ procedures for sc...@>= -static void get_x_or_protected(void) /*sets |cur_cmd|, |cur_chr|, |cur_tok|, - and expands non-protected macros*/ -{@+ -loop@+{@+get_token(); - if (cur_cmd <= max_command) return; - if ((cur_cmd >= call)&&(cur_cmd < end_template)) - if (info(link(cur_chr))==protected_token) return; - expand(); - } -} - -@ A group entered (or a conditional started) in one file may end in a -different file. Such slight anomalies, although perfectly legitimate, -may cause errors that are difficult to locate. In order to be able to -give a warning message when such anomalies occur, \eTeX\ uses the -|grp_stack| and |if_stack| arrays to record the initial |cur_boundary| -and |cond_ptr| values for each input file. - -@<Glob...@>= -static save_pointer @!grp_stack[max_in_open+1]; /*initial |cur_boundary|*/ -static pointer @!if_stack[max_in_open+1]; /*initial |cond_ptr|*/ - -@ When a group ends that was apparently entered in a different input -file, the |group_warning| procedure is invoked in order to update the -|grp_stack|. If moreover \.{\\tracingnesting} is positive we want to -give a warning message. The situation is, however, somewhat complicated -by two facts: (1)~There may be |grp_stack| elements without a -corresponding \.{\\input} file or \.{\\scantokens} pseudo file (e.g., -error insertions from the terminal); and (2)~the relevant information is -recorded in the |name_field| of the |input_stack| only loosely -synchronized with the |in_open| variable indexing |grp_stack|. - -@<Declare \eTeX\ procedures for tr...@>= -static void group_warning(void) -{@+int i; /*index into |grp_stack|*/ -bool @!w; /*do we need a warning?*/ -base_ptr=input_ptr;input_stack[base_ptr]=cur_input; - /*store current state*/ -i=in_open;w=false; -while ((grp_stack[i]==cur_boundary)&&(i > 0)) - {@+@<Set variable |w| to indicate if this case should be reported@>; - grp_stack[i]=save_index(save_ptr);decr(i); - } -if (w) - {@+print_nl("Warning: end of ");print_group(true); -@.Warning: end of...@> - print(" of a different file");print_ln(); - if (tracing_nesting > 1) show_context(); - if (history==spotless) history=warning_issued; - } -} - -@ This code scans the input stack in order to determine the type of the -current input file. - -@<Set variable |w| to...@>= -if (tracing_nesting > 0) - {@+while ((input_stack[base_ptr].state_field==token_list)||@| - (input_stack[base_ptr].index_field > i)) decr(base_ptr); - if (input_stack[base_ptr].name_field > 17) w=true; - } - -@ When a conditional ends that was apparently started in a different -input file, the |if_warning| procedure is invoked in order to update the -|if_stack|. If moreover \.{\\tracingnesting} is positive we want to -give a warning message (with the same complications as above). - -@<Declare \eTeX\ procedures for tr...@>= -static void if_warning(void) -{@+int i; /*index into |if_stack|*/ -bool @!w; /*do we need a warning?*/ -base_ptr=input_ptr;input_stack[base_ptr]=cur_input; - /*store current state*/ -i=in_open;w=false; -while (if_stack[i]==cond_ptr) - {@+@<Set variable |w| to...@>; - if_stack[i]=link(cond_ptr);decr(i); - } -if (w) - {@+print_nl("Warning: end of ");print_cmd_chr(if_test, cur_if); -@.Warning: end of...@> - print_if_line(if_line);print(" of a different file");print_ln(); - if (tracing_nesting > 1) show_context(); - if (history==spotless) history=warning_issued; - } -} - -@ Conversely, the |file_warning| procedure is invoked when a file ends -and some groups entered or conditionals started while reading from that -file are still incomplete. - -@<Declare \eTeX\ procedures for tr...@>= -static void file_warning(void) -{@+pointer p; /*saved value of |save_ptr| or |cond_ptr|*/ -quarterword @!l; /*saved value of |cur_level| or |if_limit|*/ -quarterword @!c; /*saved value of |cur_group| or |cur_if|*/ -int @!i; /*saved value of |if_line|*/ -p=save_ptr;l=cur_level;c=cur_group;save_ptr=cur_boundary; -while (grp_stack[in_open]!=save_ptr) - {@+decr(cur_level); - print_nl("Warning: end of file when "); -@.Warning: end of file when...@> - print_group(true);print(" is incomplete");@/ - cur_group=save_level(save_ptr);save_ptr=save_index(save_ptr); - } -save_ptr=p;cur_level=l;cur_group=c; /*restore old values*/ -p=cond_ptr;l=if_limit;c=cur_if;i=if_line; -while (if_stack[in_open]!=cond_ptr) - {@+print_nl("Warning: end of file when "); -@.Warning: end of file when...@> - print_cmd_chr(if_test, cur_if); - if (if_limit==fi_code) print_esc("else"); - print_if_line(if_line);print(" is incomplete");@/ - if_line=if_line_field(cond_ptr);cur_if=subtype(cond_ptr); - if_limit=type(cond_ptr);cond_ptr=link(cond_ptr); - } -cond_ptr=p;if_limit=l;cur_if=c;if_line=i; /*restore old values*/ -print_ln(); -if (tracing_nesting > 1) show_context(); -if (history==spotless) history=warning_issued; -} - -@ Here are the additional \eTeX\ primitives for expressions. - -@<Generate all \eTeX...@>= -primitive("numexpr", last_item, eTeX_expr-int_val+int_val); -@!@:num\_expr\_}{\.{\\numexpr} primitive@> -primitive("dimexpr", last_item, eTeX_expr-int_val+dimen_val); -@!@:dim\_expr\_}{\.{\\dimexpr} primitive@> -primitive("glueexpr", last_item, eTeX_expr-int_val+glue_val); -@!@:glue\_expr\_}{\.{\\glueexpr} primitive@> -primitive("muexpr", last_item, eTeX_expr-int_val+mu_val); -@!@:mu\_expr\_}{\.{\\muexpr} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case eTeX_expr-int_val+int_val: print_esc("numexpr");@+break; -case eTeX_expr-int_val+dimen_val: print_esc("dimexpr");@+break; -case eTeX_expr-int_val+glue_val: print_esc("glueexpr");@+break; -case eTeX_expr-int_val+mu_val: print_esc("muexpr");@+break; - -@ This code for reducing |cur_val_level| and\slash or negating the -result is similar to the one for all the other cases of -|scan_something_internal|, with the difference that |scan_expr| has -already increased the reference count of a glue specification. - -@<Process an expression and |return|@>= -{@+if (m < eTeX_mu) - {@+switch (m) { - @/@<Cases for fetching a glue value@>@/ - } /*there are no other cases*/ - cur_val_level=glue_val; - } -else if (m < eTeX_expr) - {@+switch (m) { - @/@<Cases for fetching a mu value@>@/ - } /*there are no other cases*/ - cur_val_level=mu_val; - } -else{@+cur_val_level=m-eTeX_expr+int_val;scan_expr(); - } -while (cur_val_level > level) - {@+if (cur_val_level==glue_val) - {@+m=cur_val;cur_val=width(m);delete_glue_ref(m); - } - else if (cur_val_level==mu_val) mu_error(); - decr(cur_val_level); - } -if (negative) - if (cur_val_level >= glue_val) - {@+m=cur_val;cur_val=new_spec(m);delete_glue_ref(m); - @<Negate all three glue components of |cur_val|@>; - } - else negate(cur_val); -return; -} - -@ @<Declare \eTeX\ procedures for sc...@>= -static void scan_expr(void); - -@ The |scan_expr| procedure scans and evaluates an expression. - -@<Declare procedures needed for expressions@>= -@t\4@>@<Declare subprocedures for |scan_expr|@>@; -static void scan_expr(void) /*scans and evaluates an expression*/ -{@+ -bool a, @!b; /*saved values of |arith_error|*/ -small_number @!l; /*type of expression*/ -small_number @!r; /*state of expression so far*/ -small_number @!s; /*state of term so far*/ -small_number @!o; /*next operation or type of next factor*/ -int @!e; /*expression so far*/ -int @!t; /*term so far*/ -int @!f; /*current factor*/ -int @!n; /*numerator of combined multiplication and division*/ -pointer @!p; /*top of expression stack*/ -pointer @!q; /*for stack manipulations*/ -l=cur_val_level;a=arith_error;b=false;p=null; -@<Scan and evaluate an expression |e| of type |l|@>; -if (b) - {@+print_err("Arithmetic overflow"); -@.Arithmetic overflow@> - help2("I can't evaluate this expression,",@/ - "since the result is out of range."); - error(); - if (l >= glue_val) - {@+delete_glue_ref(e);e=zero_glue;add_glue_ref(e); - } - else e=0; - } -arith_error=a;cur_val=e;cur_val_level=l; -} - -@ Evaluating an expression is a recursive process: When the left -parenthesis of a subexpression is scanned we descend to the next level -of recursion; the previous level is resumed with the matching right -parenthesis. - -@d expr_none 0 /*\.( seen, or \.( $\langle\it expr\rangle$ \.) seen*/ -@d expr_add 1 /*\.( $\langle\it expr\rangle$ \.+ seen*/ -@d expr_sub 2 /*\.( $\langle\it expr\rangle$ \.- seen*/ -@d expr_mult 3 /*$\langle\it term\rangle$ \.* seen*/ -@d expr_div 4 /*$\langle\it term\rangle$ \./ seen*/ -@d expr_scale 5 /*$\langle\it term\rangle$ \.* - $\langle\it factor\rangle$ \./ seen*/ - -@<Scan and eval...@>= -restart: r=expr_none;e=0;s=expr_none;t=0;n=0; -resume: if (s==expr_none) o=l;@+else o=int_val; -@<Scan a factor |f| of type |o| or start a subexpression@>; -found: @<Scan the next operator and set |o|@>; -arith_error=b; -@<Make sure that |f| is in the proper range@>; -switch (s) {@<Cases for evaluation of the current term@>@; -} /*there are no other cases*/ -if (o > expr_sub) s=o;@+else@<Evaluate the current expression@>; -b=arith_error; -if (o!=expr_none) goto resume; -if (p!=null) @<Pop the expression stack and |goto found|@>@; - -@ @<Scan the next op...@>= -@<Get the next non-blank non-call token@>; -if (cur_tok==other_token+'+') o=expr_add; -else if (cur_tok==other_token+'-') o=expr_sub; -else if (cur_tok==other_token+'*') o=expr_mult; -else if (cur_tok==other_token+'/') o=expr_div; -else{@+o=expr_none; - if (p==null) - {@+if (cur_cmd!=relax) back_input(); - } - else if (cur_tok!=other_token+')') - {@+print_err("Missing ) inserted for expression"); -@.Missing ) inserted@> - help1("I was expecting to see `+', `-', `*', `/', or `)'. Didn't."); - back_error(); - } - } - -@ @<Scan a factor...@>= -@<Get the next non-blank non-call token@>; -if (cur_tok==other_token+'(') - @<Push the expression stack and |goto restart|@>; -back_input(); -if (o==int_val) scan_int(); -else if (o==dimen_val) scan_normal_dimen; -else if (o==glue_val) scan_normal_glue(); -else scan_mu_glue(); -f=cur_val - -@ @<Declare \eTeX\ procedures for sc...@>= -static void scan_normal_glue(void);@/ -static void scan_mu_glue(void); - -@ Here we declare two trivial procedures in order to avoid mutually -recursive procedures with parameters. - -@<Declare procedures needed for expressions@>= -static void scan_normal_glue(void) -{@+scan_glue(glue_val); -} -@# -static void scan_mu_glue(void) -{@+scan_glue(mu_val); -} - -@ Parenthesized subexpressions can be inside expressions, and this -nesting has a stack. Seven local variables represent the top of the -expression stack: |p| points to pushed-down entries, if any; |l| -specifies the type of expression currently beeing evaluated; |e| is the -expression so far and |r| is the state of its evaluation; |t| is the -term so far and |s| is the state of its evaluation; finally |n| is the -numerator for a combined multiplication and division, if any. - -@d expr_node_size 4 /*number of words in stack entry for subexpressions*/ -@d expr_e_field(A) mem[A+1].i /*saved expression so far*/ -@d expr_t_field(A) mem[A+2].i /*saved term so far*/ -@d expr_n_field(A) mem[A+3].i /*saved numerator*/ - -@<Push the expression...@>= -{@+q=get_node(expr_node_size);link(q)=p;type(q)=l; -subtype(q)=4*s+r; -expr_e_field(q)=e;expr_t_field(q)=t;expr_n_field(q)=n; -p=q;l=o;goto restart; -} - -@ @<Pop the expression...@>= -{@+f=e;q=p; -e=expr_e_field(q);t=expr_t_field(q);n=expr_n_field(q); -s=subtype(q)/4;r=subtype(q)%4; -l=type(q);p=link(q);free_node(q, expr_node_size); -goto found; -} - -@ We want to make sure that each term and (intermediate) result is in -the proper range. Integer values must not exceed |infinity| -($2^{31}-1$) in absolute value, dimensions must not exceed |max_dimen| -($2^{30}-1$). We avoid the absolute value of an integer, because this -might fail for the value $-2^{31}$ using 32-bit arithmetic. - -@d num_error(A) /*clear a number or dimension and set |arith_error|*/ - {@+arith_error=true;A=0; - } -@d glue_error(A) /*clear a glue spec and set |arith_error|*/ - {@+arith_error=true;delete_glue_ref(A);A=new_spec(zero_glue); - } - -@<Make sure that |f|...@>= -if ((l==int_val)||(s > expr_sub)) - {@+if ((f > infinity)||(f < -infinity)) num_error(f); - } -else if (l==dimen_val) - {@+if (abs(f) > max_dimen) num_error(f); - } -else{@+if ((abs(width(f)) > max_dimen)||@| - (abs(stretch(f)) > max_dimen)||@| - (abs(shrink(f)) > max_dimen)) glue_error(f); - } - -@ Applying the factor |f| to the partial term |t| (with the operator -|s|) is delayed until the next operator |o| has been scanned. Here we -handle the first factor of a partial term. A glue spec has to be copied -unless the next operator is a right parenthesis; this allows us later on -to simply modify the glue components. - -@d normalize_glue(A) - if (stretch(A)==0) stretch_order(A)=normal; - if (shrink(A)==0) shrink_order(A)=normal - -@<Cases for evaluation of the current term@>= -case expr_none: if ((l >= glue_val)&&(o!=expr_none)) - {@+t=new_spec(f);delete_glue_ref(f);normalize_glue(t); - } - else t=f;@+break; - -@ When a term |t| has been completed it is copied to, added to, or -subtracted from the expression |e|. - -@d expr_add_sub(A, B, C) add_or_sub(A, B, C, r==expr_sub) -@d expr_a(A, B) expr_add_sub(A, B, max_dimen) - -@<Evaluate the current expression@>= -{@+s=expr_none; -if (r==expr_none) e=t; -else if (l==int_val) e=expr_add_sub(e, t, infinity); -else if (l==dimen_val) e=expr_a(e, t); -else@<Compute the sum or difference of two glue specs@>; -r=o; -} - -@ The function |add_or_sub(x, y, max_answer, negative)| computes the sum -(for |negative==false|) or difference (for |negative==true|) of |x| and -|y|, provided the absolute value of the result does not exceed -|max_answer|. - -@<Declare subprocedures for |scan_expr|@>= -static int add_or_sub(int @!x, int @!y, int @!max_answer, bool @!negative) -{@+int a; /*the answer*/ -if (negative) negate(y); -if (x >= 0) - if (y <= max_answer-x) a=x+y;@+else num_error(a)@; -else if (y >= -max_answer-x) a=x+y;@+else num_error(a); -return a; -} - -@ We know that |stretch_order(e) > normal| implies |stretch(e)!=0| and -|shrink_order(e) > normal| implies |shrink(e)!=0|. - -@<Compute the sum or diff...@>= -{@+width(e)=expr_a(width(e), width(t)); -if (stretch_order(e)==stretch_order(t)) - stretch(e)=expr_a(stretch(e), stretch(t)); -else if ((stretch_order(e) < stretch_order(t))&&(stretch(t)!=0)) - {@+stretch(e)=stretch(t);stretch_order(e)=stretch_order(t); - } -if (shrink_order(e)==shrink_order(t)) - shrink(e)=expr_a(shrink(e), shrink(t)); -else if ((shrink_order(e) < shrink_order(t))&&(shrink(t)!=0)) - {@+shrink(e)=shrink(t);shrink_order(e)=shrink_order(t); - } -delete_glue_ref(t);normalize_glue(e); -} - -@ If a multiplication is followed by a division, the two operations are -combined into a `scaling' operation. Otherwise the term |t| is -multiplied by the factor |f|. - -@d expr_m(A) A=nx_plus_y(A, f, 0) - -@<Cases for evaluation of the current term@>= -case expr_mult: if (o==expr_div) - {@+n=f;o=expr_scale; - } - else if (l==int_val) t=mult_integers(t, f); - else if (l==dimen_val) expr_m(t); - else{@+expr_m(width(t));expr_m(stretch(t));expr_m(shrink(t)); - } @+break; - -@ Here we divide the term |t| by the factor |f|. - -@d expr_d(A) A=quotient(A, f) - -@<Cases for evaluation of the current term@>= -case expr_div: if (l < glue_val) expr_d(t); - else{@+expr_d(width(t));expr_d(stretch(t));expr_d(shrink(t)); - } @+break; - -@ The function |quotient(n, d)| computes the rounded quotient -$q=\lfloor n/d+{1\over2}\rfloor$, when $n$ and $d$ are positive. - -@<Declare subprocedures for |scan_expr|@>= -static int quotient(int @!n, int @!d) -{@+bool negative; /*should the answer be negated?*/ -int @!a; /*the answer*/ -if (d==0) num_error(a)@; -else{@+if (d > 0) negative=false; - else{@+negate(d);negative=true; - } - if (n < 0) - {@+negate(n);negative=!negative; - } - a=n/d;n=n-a*d;d=n-d; /*avoid certain compiler optimizations!*/ - if (d+n >= 0) incr(a); - if (negative) negate(a); - } -return a; -} - -@ Here the term |t| is multiplied by the quotient $n/f$. - -@d expr_s(A) A=fract(A, n, f, max_dimen) - -@<Cases for evaluation of the current term@>= -case expr_scale: if (l==int_val) t=fract(t, n, f, infinity); - else if (l==dimen_val) expr_s(t); - else{@+expr_s(width(t));expr_s(stretch(t));expr_s(shrink(t)); - } - -@ Finally, the function |fract(x, n, d, max_answer)| computes the integer -$q=\lfloor xn/d+{1\over2}\rfloor$, when $x$, $n$, and $d$ are positive -and the result does not exceed |max_answer|. We can't use floating -point arithmetic since the routine must produce identical results in all -cases; and it would be too dangerous to multiply by~|n| and then divide -by~|d|, in separate operations, since overflow might well occur. Hence -this subroutine simulates double precision arithmetic, somewhat -analogous to \MF's |make_fraction| and |take_fraction| routines. - -@<Declare subprocedures for |scan_expr|@>= -static int fract(int @!x, int @!n, int @!d, int @!max_answer) -{@+ -bool negative; /*should the answer be negated?*/ -int @!a; /*the answer*/ -int @!f; /*a proper fraction*/ -int @!h; /*smallest integer such that |2*h >= d|*/ -int @!r; /*intermediate remainder*/ -int @!t; /*temp variable*/ -if (d==0) goto too_big; -a=0; -if (d > 0) negative=false; -else{@+negate(d);negative=true; - } -if (x < 0) - {@+negate(x);negative=!negative; - } -else if (x==0) goto done; -if (n < 0) - {@+negate(n);negative=!negative; - } -t=n/d; -if (t > max_answer/x) goto too_big; -a=t*x;n=n-t*d; -if (n==0) goto found; -t=x/d; -if (t > (max_answer-a)/n) goto too_big; -a=a+t*n;x=x-t*d; -if (x==0) goto found; -if (x < n) - {@+t=x;x=n;n=t; - } /*now |0 < n <= x < d|*/ -@<Compute \(f)$f=\lfloor xn/d+{1\over2}\rfloor$@>@; -if (f > (max_answer-a)) goto too_big; -a=a+f; -found: if (negative) negate(a); -goto done; -too_big: num_error(a); -done: return a; -} - -@ The loop here preserves the following invariant relations -between |f|, |x|, |n|, and~|r|: -(i)~$f+\lfloor(xn+(r+d))/d\rfloor=\lfloor x_0n_0/d+{1\over2}\rfloor$; -(ii)~|-d <= r < 0 < n <= x < d|, where $x_0$, $n_0$ are the original values of~$x$ -and $n$. - -Notice that the computation specifies |(x-d)+x| instead of |(x+x)-d|, -because the latter could overflow. - -@<Compute \(f)$f=\lfloor xn/d+{1\over2}\rfloor$@>= -f=0;r=(d/2)-d;h=-r; -loop@+{@+if (odd(n)) - {@+r=r+x; - if (r >= 0) - {@+r=r-d;incr(f); - } - } - n=n/2; - if (n==0) goto found1; - if (x < h) x=x+x; - else{@+t=x-d;x=t+x;f=f+n; - if (x < n) - {@+if (x==0) goto found1; - t=x;x=n;n=t; - } - } - } -found1: - -@ The \.{\\gluestretch}, \.{\\glueshrink}, \.{\\gluestretchorder}, and -\.{\\glueshrinkorder} commands return the stretch and shrink components -and their orders of ``infinity'' of a glue specification. - -@d glue_stretch_order_code (eTeX_int+6) /*code for \.{\\gluestretchorder}*/ -@d glue_shrink_order_code (eTeX_int+7) /*code for \.{\\glueshrinkorder}*/ -@d glue_stretch_code (eTeX_dim+7) /*code for \.{\\gluestretch}*/ -@d glue_shrink_code (eTeX_dim+8) /*code for \.{\\glueshrink}*/ - -@<Generate all \eTeX...@>= -primitive("gluestretchorder", last_item, glue_stretch_order_code); -@!@:glue\_stretch\_order\_}{\.{\\gluestretchorder} primitive@> -primitive("glueshrinkorder", last_item, glue_shrink_order_code); -@!@:glue\_shrink\_order\_}{\.{\\glueshrinkorder} primitive@> -primitive("gluestretch", last_item, glue_stretch_code); -@!@:glue\_stretch\_}{\.{\\gluestretch} primitive@> -primitive("glueshrink", last_item, glue_shrink_code); -@!@:glue\_shrink\_}{\.{\\glueshrink} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case glue_stretch_order_code: print_esc("gluestretchorder");@+break; -case glue_shrink_order_code: print_esc("glueshrinkorder");@+break; -case glue_stretch_code: print_esc("gluestretch");@+break; -case glue_shrink_code: print_esc("glueshrink");@+break; - -@ @<Cases for fetching an integer value@>= -case glue_stretch_order_code: case glue_shrink_order_code: - {@+scan_normal_glue();q=cur_val; - if (m==glue_stretch_order_code) cur_val=stretch_order(q); - else cur_val=shrink_order(q); - delete_glue_ref(q); - } - -@ @<Cases for fetching a dimension value@>= -case glue_stretch_code: case glue_shrink_code: - {@+scan_normal_glue();q=cur_val; - if (m==glue_stretch_code) cur_val=stretch(q); - else cur_val=shrink(q); - delete_glue_ref(q); - } - -@ The \.{\\mutoglue} and \.{\\gluetomu} commands convert ``math'' glue -into normal glue and vice versa; they allow to manipulate math glue with -\.{\\gluestretch} etc. - -@d mu_to_glue_code eTeX_glue /*code for \.{\\mutoglue}*/ -@d glue_to_mu_code eTeX_mu /*code for \.{\\gluetomu}*/ - -@<Generate all \eTeX...@>= -primitive("mutoglue", last_item, mu_to_glue_code); -@!@:mu\_to\_glue\_}{\.{\\mutoglue} primitive@> -primitive("gluetomu", last_item, glue_to_mu_code); -@!@:glue\_to\_mu\_}{\.{\\gluetomu} primitive@> - -@ @<Cases of |last_item| for |print_cmd_chr|@>= -case mu_to_glue_code: print_esc("mutoglue");@+break; -case glue_to_mu_code: print_esc("gluetomu");@+break; - -@ @<Cases for fetching a glue value@>= -case mu_to_glue_code: scan_mu_glue(); - -@ @<Cases for fetching a mu value@>= -case glue_to_mu_code: scan_normal_glue(); - -@ \eTeX\ (in extended mode) supports 32768 (i.e., $2^{15}$) count, -dimen, skip, muskip, box, and token registers. As in \TeX\ the first -256 registers of each kind are realized as arrays in the table of -equivalents; the additional registers are realized as tree structures -built from variable-size nodes with individual registers existing only -when needed. Default values are used for nonexistent registers: zero -for count and dimen values, |zero_glue| for glue (skip and muskip) -values, void for boxes, and |null| for token lists (and current marks -discussed below). - - -@ The |scan_register_num| procedure scans a register number that must -not exceed 255 in compatibility mode resp.\ 32767 in extended mode. - -@<Declare \eTeX\ procedures for ex...@>= -static void scan_register_num(void); - -@ @<Declare procedures that scan restricted classes of integers@>= -static void scan_register_num(void) -{@+scan_int(); -if ((cur_val < 0)||(cur_val > max_reg_num)) - {@+print_err("Bad register code"); -@.Bad register code@> - help2(max_reg_help_line,"I changed this one to zero."); - int_error(cur_val);cur_val=0; - } -} - -@ @<Initialize variables for \eTeX\ comp...@>= -max_reg_num=255; -max_reg_help_line="A register number must be between 0 and 255."; - -@ @<Initialize variables for \eTeX\ ext...@>= -max_reg_num=32767; -max_reg_help_line="A register number must be between 0 and 32767."; - -@ @<Glob...@>= -static halfword @!max_reg_num; /*largest allowed register number*/ -static char *@!max_reg_help_line; /*first line of help message*/ - -@ There are seven almost identical doubly linked trees, one for the -sparse array of the up to 32512 additional registers of each kind and -one for the sparse array of the up to 32767 additional mark classes. -The root of each such tree, if it exists, is an index node containing 16 -pointers to subtrees for 4096 consecutive array elements. Similar index -nodes are the starting points for all nonempty subtrees for 4096, 256, -and 16 consecutive array elements. These four levels of index nodes are -followed by a fifth level with nodes for the individual array elements. - -Each index node is nine words long. The pointers to the 16 possible -subtrees or are kept in the |info| and |link| fields of the last eight -words. (It would be both elegant and efficient to declare them as -array, unfortunately \PASCAL\ doesn't allow this.) - -The fields in the first word of each index node and in the nodes for the -array elements are closely related. The |link| field points to the next -lower index node and the |sa_index| field contains four bits (one -hexadecimal digit) of the register number or mark class. For the lowest -index node the |link| field is |null| and the |sa_index| field indicates -the type of quantity (|int_val|, |dimen_val|, |glue_val|, |mu_val|, -|box_val|, |tok_val|, or |mark_val|). The |sa_used| field in the index -nodes counts how many of the 16 pointers are non-null. - -The |sa_index| field in the nodes for array elements contains the four -bits plus 16 times the type. Therefore such a node represents a count -or dimen register if and only if |sa_index < dimen_val_limit|; it -represents a skip or muskip register if and only if -|dimen_val_limit <= sa_index < mu_val_limit|; it represents a box register -if and only if |mu_val_limit <= sa_index < box_val_limit|; it represents a -token list register if and only if -|box_val_limit <= sa_index < tok_val_limit|; finally it represents a mark -class if and only if |tok_val_limit <= sa_index|. - -The |new_index| procedure creates an index node (returned in |cur_ptr|) -having given contents of the |sa_index| and |link| fields. - -@d box_val 4 /*the additional box registers*/ -@d mark_val 6 /*the additional mark classes*/ -@# -@d dimen_val_limit 0x20 /*$2^4\cdot(|dimen_val|+1)$*/ -@d mu_val_limit 0x40 /*$2^4\cdot(|mu_val|+1)$*/ -@d box_val_limit 0x50 /*$2^4\cdot(|box_val|+1)$*/ -@d tok_val_limit 0x60 /*$2^4\cdot(|tok_val|+1)$*/ -@# -@d index_node_size 9 /*size of an index node*/ -@d sa_index(A) type(A) /*a four-bit address or a type or both*/ -@d sa_used(A) subtype(A) /*count of non-null pointers*/ - -@<Declare \eTeX\ procedures for ex...@>= -static void new_index(quarterword @!i, pointer @!q) -{@+int k; /*loop index*/ -cur_ptr=get_node(index_node_size);sa_index(cur_ptr)=i; -sa_used(cur_ptr)=0;link(cur_ptr)=q; -for (k=1; k<=index_node_size-1; k++) /*clear all 16 pointers*/ - mem[cur_ptr+k]=sa_null; -} - -@ The roots of the seven trees for the additional registers and mark -classes are kept in the |sa_root| array. The first six locations must -be dumped and undumped; the last one is also known as |sa_mark|. - -@d sa_mark sa_root[mark_val] /*root for mark classes*/ - -@<Glob...@>= -static pointer @!sa_root0[mark_val-int_val+1], *const @!sa_root = @!sa_root0-int_val; /*roots of sparse arrays*/ -static pointer @!cur_ptr; /*value returned by |new_index| and |find_sa_element|*/ -static memory_word @!sa_null; /*two |null| pointers*/ - -@ @<Set init...@>= -sa_mark=null;sa_null.hh.lh=null;sa_null.hh.rh=null; - -@ @<Initialize table...@>= -for (i=int_val; i<=tok_val; i++) sa_root[i]=null; - -@ Given a type |t| and a sixteen-bit number |n|, the |find_sa_element| -procedure returns (in |cur_ptr|) a pointer to the node for the -corresponding array element, or |null| when no such element exists. The -third parameter |w| is set |true| if the element must exist, e.g., -because it is about to be modified. The procedure has two main -branches: one follows the existing tree structure, the other (only used -when |w| is |true|) creates the missing nodes. - -We use macros to extract the four-bit pieces from a sixteen-bit register -number or mark class and to fetch or store one of the 16 pointers from -an index node. - -@d if_cur_ptr_is_null_then_return_or_goto(A) /*some tree element is missing*/ - {@+if (cur_ptr==null) - if (w) goto A;@+else return; - } -@# -@d hex_dig1(A) A/4096 /*the fourth lowest hexadecimal digit*/ -@d hex_dig2(A) (A/256)%16 /*the third lowest hexadecimal digit*/ -@d hex_dig3(A) (A/16)%16 /*the second lowest hexadecimal digit*/ -@d hex_dig4(A) A%16 /*the lowest hexadecimal digit*/ -@# -@d get_sa_ptr if (odd(i)) cur_ptr=link(q+(i/2)+1); - else cur_ptr=info(q+(i/2)+1) - /*set |cur_ptr| to the pointer indexed by |i| from index node |q|*/ -@d put_sa_ptr(A) if (odd(i)) link(q+(i/2)+1)=A; - else info(q+(i/2)+1)=A - /*store the pointer indexed by |i| in index node |q|*/ -@d add_sa_ptr {@+put_sa_ptr(cur_ptr);incr(sa_used(q)); - } /*add |cur_ptr| as the pointer indexed by |i| in index node |q|*/ -@d delete_sa_ptr {@+put_sa_ptr(null);decr(sa_used(q)); - } /*delete the pointer indexed by |i| in index node |q|*/ - -@<Declare \eTeX\ procedures for ex...@>= -static void find_sa_element(small_number @!t, halfword @!n, bool @!w) - /*sets |cur_val| to sparse array element location or |null|*/ -{@+ -pointer q; /*for list manipulations*/ -small_number @!i; /*a four bit index*/ -cur_ptr=sa_root[t]; -if_cur_ptr_is_null_then_return_or_goto(not_found);@/ -q=cur_ptr;i=hex_dig1(n);get_sa_ptr; -if_cur_ptr_is_null_then_return_or_goto(not_found1);@/ -q=cur_ptr;i=hex_dig2(n);get_sa_ptr; -if_cur_ptr_is_null_then_return_or_goto(not_found2);@/ -q=cur_ptr;i=hex_dig3(n);get_sa_ptr; -if_cur_ptr_is_null_then_return_or_goto(not_found3);@/ -q=cur_ptr;i=hex_dig4(n);get_sa_ptr; -if ((cur_ptr==null)&&w) goto not_found4; -return; -not_found: new_index(t, null); /*create first level index node*/ -sa_root[t]=cur_ptr;q=cur_ptr;i=hex_dig1(n); -not_found1: new_index(i, q); /*create second level index node*/ -add_sa_ptr;q=cur_ptr;i=hex_dig2(n); -not_found2: new_index(i, q); /*create third level index node*/ -add_sa_ptr;q=cur_ptr;i=hex_dig3(n); -not_found3: new_index(i, q); /*create fourth level index node*/ -add_sa_ptr;q=cur_ptr;i=hex_dig4(n); -not_found4: @<Create a new array element of type |t| with index |i|@>; -link(cur_ptr)=q;add_sa_ptr; -} - -@ The array elements for registers are subject to grouping and have an -|sa_lev| field (quite analogous to |eq_level|) instead of |sa_used|. -Since saved values as well as shorthand definitions (created by e.g., -\.{\\countdef}) refer to the location of the respective array element, -we need a reference count that is kept in the |sa_ref| field. An array -element can be deleted (together with all references to it) when its -|sa_ref| value is |null| and its value is the default value. -@^reference counts@> - -Skip, muskip, box, and token registers use two word nodes, their values -are stored in the |sa_ptr| field. -Count and dimen registers use three word nodes, their -values are stored in the |sa_int| resp.\ |sa_dim| field in the third -word; the |sa_ptr| field is used under the name |sa_num| to store -the register number. Mark classes use four word nodes. The last three -words contain the five types of current marks - -@d sa_lev sa_used /*grouping level for the current value*/ -@d pointer_node_size 2 /*size of an element with a pointer value*/ -@d sa_type(A) (sa_index(A)/16) /*type part of combined type/index*/ -@d sa_ref(A) info(A+1) /*reference count of a sparse array element*/ -@d sa_ptr(A) link(A+1) /*a pointer value*/ -@# -@d word_node_size 3 /*size of an element with a word value*/ -@d sa_num(A) sa_ptr(A) /*the register number*/ -@d sa_int(A) mem[A+2].i /*an integer*/ -@d sa_dim(A) mem[A+2].sc /*a dimension (a somewhat esotheric distinction)*/ -@# -@d mark_class_node_size 4 /*size of an element for a mark class*/ -@# -@d fetch_box(A) /*fetch |box(cur_val)|*/ - if (cur_val < 256) A=box(cur_val); - else{@+find_sa_element(box_val, cur_val, false); - if (cur_ptr==null) A=null;@+else A=sa_ptr(cur_ptr); - } - -@<Create a new array element...@>= -if (t==mark_val) /*a mark class*/ - {@+cur_ptr=get_node(mark_class_node_size); - mem[cur_ptr+1]=sa_null;mem[cur_ptr+2]=sa_null;mem[cur_ptr+3]=sa_null; - } -else{@+if (t <= dimen_val) /*a count or dimen register*/ - {@+cur_ptr=get_node(word_node_size);sa_int(cur_ptr)=0; - sa_num(cur_ptr)=n; - } - else{@+cur_ptr=get_node(pointer_node_size); - if (t <= mu_val) /*a skip or muskip register*/ - {@+sa_ptr(cur_ptr)=zero_glue;add_glue_ref(zero_glue); - } - else sa_ptr(cur_ptr)=null; /*a box or token list register*/ - } - sa_ref(cur_ptr)=null; /*all registers have a reference count*/ - } -sa_index(cur_ptr)=16*t+i;sa_lev(cur_ptr)=level_one - -@ The |delete_sa_ref| procedure is called when a pointer to an array -element representing a register is being removed; this means that the -reference count should be decreased by one. If the reduced reference -count is |null| and the register has been (globally) assigned its -default value the array element should disappear, possibly together with -some index nodes. This procedure will never be used for mark class -nodes. -@^reference counts@> - -@d add_sa_ref(A) incr(sa_ref(A)) /*increase reference count*/ -@# -@d change_box(A) /*change |box(cur_val)|, the |eq_level| stays the same*/ - if (cur_val < 256) box(cur_val)=A;@+else set_sa_box(A) -@# -@d set_sa_box(X) {@+find_sa_element(box_val, cur_val, false); - if (cur_ptr!=null) - {@+sa_ptr(cur_ptr)=X;add_sa_ref(cur_ptr);delete_sa_ref(cur_ptr); - } - } - -@<Declare \eTeX\ procedures for tr...@>= -static void delete_sa_ref(pointer @!q) /*reduce reference count*/ -{@+ -pointer p; /*for list manipulations*/ -small_number @!i; /*a four bit index*/ -small_number @!s; /*size of a node*/ -decr(sa_ref(q)); -if (sa_ref(q)!=null) return; -if (sa_index(q) < dimen_val_limit) - if (sa_int(q)==0) s=word_node_size; - else return; -else{@+if (sa_index(q) < mu_val_limit) - if (sa_ptr(q)==zero_glue) delete_glue_ref(zero_glue); - else return; - else if (sa_ptr(q)!=null) return; - s=pointer_node_size; - } -@/do@+{i=hex_dig4(sa_index(q));p=q;q=link(p);free_node(p, s); -if (q==null) /*the whole tree has been freed*/ - {@+sa_root[i]=null;return; - } -delete_sa_ptr;s=index_node_size; /*node |q| is an index node*/ -}@+ while (!(sa_used(q) > 0)); -} - -@ The |print_sa_num| procedure prints the register number corresponding -to an array element. - -@<Basic print...@>= -static void print_sa_num(pointer @!q) /*print register number*/ -{@+halfword @!n; /*the register number*/ -if (sa_index(q) < dimen_val_limit) n=sa_num(q); /*the easy case*/ -else{@+n=hex_dig4(sa_index(q));q=link(q);n=n+16*sa_index(q); - q=link(q);n=n+256*(sa_index(q)+16*sa_index(link(q))); - } -print_int(n); -} - -@ Here is a procedure that displays the contents of an array element -symbolically. It is used under similar circumstances as is -|restore_trace| (together with |show_eqtb|) for the quantities kept in -the |eqtb| array. - -@<Declare \eTeX\ procedures for tr...@>= -#ifdef @!STAT -static void show_sa(pointer @!p, char *@!s) -{@+small_number t; /*the type of element*/ -begin_diagnostic();print_char('{');print(s);print_char(' '); -if (p==null) print_char('?'); /*this can't happen*/ -else{@+t=sa_type(p); - if (t < box_val) print_cmd_chr(internal_register, p); - else if (t==box_val) - {@+print_esc("box");print_sa_num(p); - } - else if (t==tok_val) print_cmd_chr(toks_register, p); - else print_char('?'); /*this can't happen either*/ - print_char('='); - if (t==int_val) print_int(sa_int(p)); - else if (t==dimen_val) - {@+print_scaled(sa_dim(p));print("pt"); - } - else{@+p=sa_ptr(p); - if (t==glue_val) print_spec(p,"pt"); - else if (t==mu_val) print_spec(p,"mu"); - else if (t==box_val) - if (p==null) print("void"); - else{@+depth_threshold=0;breadth_max=1;show_node_list(p); - } - else if (t==tok_val) - {@+if (p!=null) show_token_list(link(p), null, 32); - } - else print_char('?'); /*this can't happen either*/ - } - } -print_char('}');end_diagnostic(false); -} -#endif - -@ The command code |internal_register| is used for `\.{\\count}', `\.{\\dimen}', -etc., as well as for references to sparse array elements defined by -`\.{\\countdef}', etc. - -@<Cases of |register| for |print_cmd_chr|@>= -{@+if ((chr_code < mem_bot)||(chr_code > lo_mem_stat_max)) - cmd=sa_type(chr_code); -else{@+cmd=chr_code-mem_bot;chr_code=null; - } -if (cmd==int_val) print_esc("count"); -else if (cmd==dimen_val) print_esc("dimen"); -else if (cmd==glue_val) print_esc("skip"); -else print_esc("muskip"); -if (chr_code!=null) print_sa_num(chr_code); -} - -@ Similarly the command code |toks_register| is used for `\.{\\toks}' as -well as for references to sparse array elements defined by -`\.{\\toksdef}'. - -@<Cases of |toks_register| for |print_cmd_chr|@>= -{@+print_esc("toks"); -if (chr_code!=mem_bot) print_sa_num(chr_code); -} - -@ When a shorthand definition for an element of one of the sparse arrays -is destroyed, we must reduce the reference count. - -@<Cases for |eq_destroy|@>= -case toks_register: case internal_register: - if ((equiv_field(w) < mem_bot)||(equiv_field(w) > lo_mem_stat_max)) - delete_sa_ref(equiv_field(w));@+break; - -@ The task to maintain (change, save, and restore) register values is -essentially the same when the register is realized as sparse array -element or entry in |eqtb|. The global variable |sa_chain| is the head -of a linked list of entries saved at the topmost level |sa_level|; the -lists for lowel levels are kept in special save stack entries. - -@<Glob...@>= -static pointer @!sa_chain; /*chain of saved sparse array entries*/ -static quarterword @!sa_level; /*group level for |sa_chain|*/ - -@ @<Set init...@>= -sa_chain=null;sa_level=level_zero; - -@ The individual saved items are kept in pointer or word nodes similar -to those used for the array elements: a word node with value zero is, -however, saved as pointer node with the otherwise impossible |sa_index| -value |tok_val_limit|. - -@d sa_loc(A) sa_ref(A) /*location of saved item*/ - -@<Declare \eTeX\ procedures for tr...@>= -static void sa_save(pointer @!p) /*saves value of |p|*/ -{@+pointer q; /*the new save node*/ -quarterword @!i; /*index field of node*/ -if (cur_level!=sa_level) - {@+check_full_save_stack;save_type(save_ptr)=restore_sa; - save_level(save_ptr)=sa_level;save_index(save_ptr)=sa_chain; - incr(save_ptr);sa_chain=null;sa_level=cur_level; - } -i=sa_index(p); -if (i < dimen_val_limit) - {@+if (sa_int(p)==0) - {@+q=get_node(pointer_node_size);i=tok_val_limit; - } - else{@+q=get_node(word_node_size);sa_int(q)=sa_int(p); - } - sa_ptr(q)=null; - } -else{@+q=get_node(pointer_node_size);sa_ptr(q)=sa_ptr(p); - } -sa_loc(q)=p;sa_index(q)=i;sa_lev(q)=sa_lev(p); -link(q)=sa_chain;sa_chain=q;add_sa_ref(p); -} - -@ @<Declare \eTeX\ procedures for tr...@>= -static void sa_destroy(pointer @!p) /*destroy value of |p|*/ -{@+if (sa_index(p) < mu_val_limit) delete_glue_ref(sa_ptr(p)); -else if (sa_ptr(p)!=null) - if (sa_index(p) < box_val_limit) flush_node_list(sa_ptr(p)); - else delete_token_ref(sa_ptr(p)); -} - -@ The procedure |sa_def| assigns a new value to sparse array elements, -and saves the former value if appropriate. This procedure is used only -for skip, muskip, box, and token list registers. The counterpart of -|sa_def| for count and dimen registers is called |sa_w_def|. - -@d sa_define(A, B, C, D, E) if (e) - if (global) gsa_def(A, B);@+else sa_def(A, B); - else if (global) geq_define(C, D, E);@+else eq_define(C, D, E) -@# -@d sa_def_box /*assign |cur_box| to |box(cur_val)|*/ - {@+find_sa_element(box_val, cur_val, true); - if (global) gsa_def(cur_ptr, cur_box);@+else sa_def(cur_ptr, cur_box); - } -@# -@d sa_word_define(A, B) if (e) - if (global) gsa_w_def(A, B);@+else sa_w_def(A, B); - else word_define(A, B) - -@<Declare \eTeX\ procedures for tr...@>= -static void sa_def(pointer @!p, halfword @!e) - /*new data for sparse array elements*/ -{@+add_sa_ref(p); -if (sa_ptr(p)==e) - { -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"reassigning"); -#endif -@;@/ - sa_destroy(p); - } -else{ -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"changing"); -#endif -@;@/ - if (sa_lev(p)==cur_level) sa_destroy(p);@+else sa_save(p); - sa_lev(p)=cur_level;sa_ptr(p)=e; -#ifdef @!STAT - if (tracing_assigns > 0) show_sa(p,"into"); -#endif -@;@/ - } -delete_sa_ref(p); -} -@# -static void sa_w_def(pointer @!p, int @!w) -{@+add_sa_ref(p); -if (sa_int(p)==w) - { -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"reassigning"); -#endif -@;@/ - } -else{ -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"changing"); -#endif -@;@/ - if (sa_lev(p)!=cur_level) sa_save(p); - sa_lev(p)=cur_level;sa_int(p)=w; -#ifdef @!STAT - if (tracing_assigns > 0) show_sa(p,"into"); -#endif -@;@/ - } -delete_sa_ref(p); -} - -@ The |sa_def| and |sa_w_def| routines take care of local definitions. -@^global definitions@> -Global definitions are done in almost the same way, but there is no need -to save old values, and the new value is associated with |level_one|. - -@<Declare \eTeX\ procedures for tr...@>= -static void gsa_def(pointer @!p, halfword @!e) /*global |sa_def|*/ -{@+add_sa_ref(p); -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"globally changing"); -#endif -@;@/ -sa_destroy(p);sa_lev(p)=level_one;sa_ptr(p)=e; -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"into"); -#endif -@;@/ -delete_sa_ref(p); -} -@# -static void gsa_w_def(pointer @!p, int @!w) /*global |sa_w_def|*/ -{@+add_sa_ref(p); -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"globally changing"); -#endif -@;@/ -sa_lev(p)=level_one;sa_int(p)=w; -#ifdef @!STAT -if (tracing_assigns > 0) show_sa(p,"into"); -#endif -@;@/ -delete_sa_ref(p); -} - -@ The |sa_restore| procedure restores the sparse array entries pointed -at by |sa_chain| - -@<Declare \eTeX\ procedures for tr...@>= -static void sa_restore(void) -{@+pointer p; /*sparse array element*/ -@/do@+{p=sa_loc(sa_chain); -if (sa_lev(p)==level_one) - {@+if (sa_index(p) >= dimen_val_limit) sa_destroy(sa_chain); -#ifdef @!STAT - if (tracing_restores > 0) show_sa(p,"retaining"); -#endif -@;@/ - } -else{@+if (sa_index(p) < dimen_val_limit) - if (sa_index(sa_chain) < dimen_val_limit) sa_int(p)=sa_int(sa_chain); - else sa_int(p)=0; - else{@+sa_destroy(p);sa_ptr(p)=sa_ptr(sa_chain); - } - sa_lev(p)=sa_lev(sa_chain); -#ifdef @!STAT - if (tracing_restores > 0) show_sa(p,"restoring"); -#endif -@;@/ - } -delete_sa_ref(p); -p=sa_chain;sa_chain=link(p); -if (sa_index(p) < dimen_val_limit) free_node(p, word_node_size); -else free_node(p, pointer_node_size); -}@+ while (!(sa_chain==null)); -} - - -@ The \.{\\interlinepenalties}, \.{\\clubpenalties}, \.{\\widowpenalties}, -and \.{\\displaywidowpenalties} commands allow to define arrays of -penalty values to be used instead of the corresponding single values. - -@d inter_line_penalties_ptr equiv(inter_line_penalties_loc) -@<Generate all \eTeX...@>= -primitive("interlinepenalties", set_shape, inter_line_penalties_loc);@/ -@!@:inter\_line\_penalties\_}{\.{\\interlinepenalties} primitive@> -primitive("clubpenalties", set_shape, club_penalties_loc);@/ -@!@:club\_penalties\_}{\.{\\clubpenalties} primitive@> -primitive("widowpenalties", set_shape, widow_penalties_loc);@/ -@!@:widow\_penalties\_}{\.{\\widowpenalties} primitive@> -primitive("displaywidowpenalties", set_shape, display_widow_penalties_loc);@/ -@!@:display\_widow\_penalties\_}{\.{\\displaywidowpenalties} primitive@> - -@ @<Cases of |set_shape| for |print_cmd_chr|@>= -case inter_line_penalties_loc: print_esc("interlinepenalties");@+break; -case club_penalties_loc: print_esc("clubpenalties");@+break; -case widow_penalties_loc: print_esc("widowpenalties");@+break; -case display_widow_penalties_loc: print_esc("displaywidowpenalties"); - -@ @<Fetch a penalties array element@>= -{@+scan_int(); -if ((equiv(m)==null)||(cur_val < 0)) cur_val=0; -else{@+if (cur_val > penalty(equiv(m))) cur_val=penalty(equiv(m)); - cur_val=penalty(equiv(m)+cur_val); - } -} - -@* System-dependent changes. -This section should be replaced, if necessary, by any special -modifications of the program -that are necessary to make \TeX\ work at a particular installation. -It is usually best to design your change file so that all changes to -previous sections preserve the section numbering; then everybody's version -will be consistent with the published program. More extensive changes, -which introduce new sections, can be inserted here; then only the index -itself will get a new section number. -@^system dependencies@> - -@* \TeX\ Live Integration. -A \TeX\ engine that aspires -to become a member of the \TeX\ Live family of programs -must - -$-$ respect the \TeX\ Live conventions for command line parameters,\par -$-$ find its input files using the \.{kpathsearch} library, and\par -$-$ implement \TeX\ primitives to support -\def\LaTeX{L\kern-.36em\raise.3ex\hbox{\sc A}\kern-.15em\TeX}% -\LaTeX. - -\noindent Naturally, the functions that follow here are taken, with small -modifications, from the \TeX\ Live sources. What is -added here, or rather subtracted here, are the parts that are specific -to some of the \TeX\ engines included in \TeX\ Live. New is also -that the code is presented in literate programming style. - -The code that follows is organized in three parts. -Some code for k\TeX\ must come before -the definition of \TeX's macros because -it uses include files containing identifiers that are in conflict -with \TeX's macros. The remaining two parts are first auxiliar functions and then -those functions that are called from the ``classic'' \TeX\ code. - -@p @<k\TeX\ auxiliar functions@>@; - @<k\TeX\ functions@>@; - -@ Let's begin with the beginning: the command line. -To see how a command line is structured, we first look at the -help text that is displayed if the user asks for it (or if \TeX\ -decides that the user needs it). The help text is produced by the -function |usage_help|. -\def\SP{ }% disable visible spaces in strings. - -@<k\TeX\ auxiliar functions@>= -static void usage_help(void) -{@+@<explain the command line@>@; - @<explain the options@>@; - fprintf(stderr,"\nEmail bug reports to ruckert@@cs.hm.edu.\n"); - exit(0); -} - -@ The command line commes in three slightly different versions: - -@<explain the command line@>= - fprintf(stderr,@/ - "Usage: %s [OPTION]... [TEXNAME[.tex]] [COMMANDS]\n"@/ - " or: %s [OPTION]... \\FIRST-LINE\n"@/ - " or: %s [OPTION]... &FMT ARGS\n\n",@/ - argv[0],argv[0],argv[0]);@/ - fprintf(stderr,@/ - " Run TeX on TEXNAME, creating TEXNAME.dvi.\n"@/ - " Any remaining COMMANDS are processed\n"@/ - " as TeX input after TEXNAME is read.\n"@/ - " If the first line of TEXNAME starts with %%&FMT, and FMT is\n"@/ - " an existing .fmt file, use it. Else use `NAME.fmt', where\n"@/ - " NAME is the program invocation name.\n"@/ - "\n"@/ - " Alternatively, if the first non-option argument begins\n"@/ - " with a backslash, interpret all non-option arguments as\n"@/ - " a line of TeX input.\n"@/ - "\n"@/ - " Alternatively, if the first non-option argument begins\n"@/ - " with a &, the next word is taken as the FMT to read,\n"@/ - " overriding all else. Any remaining arguments are\n"@/ - " processed as above.\n"@/ - "\n"@/ - " If no arguments or options are specified, prompt for input.\n"@/ - "\n"); - -@ Here is the list of possible options and their explanation: - -@<explain the options@>= - fprintf(stderr, - "Options:\n"@/ - " -help "@/ - @t\qquad@>"\t display this help and exit\n"@/ - " -version "@/ - @t\qquad@>"\t output version information and exit\n"@/ - " -etex "@/ - @t\qquad@>"\t enable e-TeX extensions\n"@/ - " -ini "@/ - @t\qquad@>"\t be initex for dumping formats; this is\n"@/ - @t\qquad@>"\t\t\t also true if the program name is `kinitex'\n"@/ - " -progname=STRING "@/ - @t\qquad@>"\t set program (and fmt) name to STRING\n"@/ - " -fmt=FMTNAME "@/ - @t\qquad@>"\t use FMTNAME instead of program name or a %%& line\n"@/ - " -output-directory=DIR "@/ - @t\qquad@>"\t use existing DIR as the directory to write files to\n"@/ - " -jobname=STRING "@/ - @t\qquad@>"\t set the TeX \\jobname to STRING\n"@/ - " [-no]-mktex=FMT "@/ - @t\qquad@>"\t disable/enable mktexFMT generation (FMT=tex/tfm/fmt/pk)\n"@/ - " -interaction=STRING "@/ - @t\qquad@>"\t set interaction mode (STRING=batchmode/\n"@/ - @t\qquad@>"\t\t\t nonstopmode/scrollmode/errorstopmode)\n"@/ - " -kpathsea-debug=NUMBER"@/ - @t\qquad@>"\t set path searching debugging flags according\n"@/ - @t\qquad@>"\t\t\t to the bits of NUMBER\n"@/ - " [-no]-parse-first-line"@/ - @t\qquad@>"\t disable/enable parsing of the first line of\n"@/ - @t\qquad@>"\t\t\t the input file\n"@/ - " [-no]-file-line-error"@/ - @t\qquad@>"\t Disable/Enable file:line:error style\n"@/ - " -cnf-line=STRING"@/ - @t\qquad@>"\t Process STRING like a line in texmf.cnf\n"@/ - " -compress "@/ - @t\qquad@>"\t enable compression of section 1 and 2\n"@/ - " [-no]-empty-page "@/ - @t\qquad@>"\t Disable/Enable empty pages\n"@/ - " -hyphenate-first-word "@/ - @t\qquad@>"\t hyphenate the first word of a paragraph\n"@/ - " -resolution=NUMBER "@/ - @t\qquad@>"\t set the resolution to NUMBER dpi\n"@/ - " -mfmode=MODE "@/ - @t\qquad@>"\t set the METAFONT mode to MODE\n"@/ -#ifdef DEBUG - " -debug=FLAGS "@/ - @t\qquad@>"\t set flags to controll hint debug output\n"@/ - " -hint-debug-help "@/ - @t\qquad@>"\t give help on hint debugging\n"@/ -#endif -); - - -@ The processing of command line options is controlled by the |long_options| -\def\SP{{\tt\char`\ }}% restore the visible space in a string -array. Each entry in this array contains first the name of the option, -then a flag that tells whether the option takes an argument or not, -then the (optional) address of a flag variable that gets set -by this option, and finally the value to store in the flag variable. - -Besides the flag variables that occur in the table, -a few string variables may be set using the options. -The following is a complete list of these variables---except -for the the |interaction| variable of \TeX. -Flag variables are initialized with |-1| to indicate an undefined value; -string variables are initialized with |NULL|. - -@<Global...@>= -static int iniversion=0; -static int etexp=0; -static int parsefirstlinep=-1; -static int filelineerrorstylep=-1; -static const char *user_progname=NULL, *output_directory=NULL, *c_job_name=NULL; -static char *dump_name=NULL;@# -int option_no_empty_page=true, option_hyphen_first=false; -int option_dpi=600; -const char *option_mfmode="ljfour", *option_dpi_str="600"; -extern int option_compress; -extern unsigned int debugflags; - -static struct option long_options[] = {@/ - { "help", 0, 0, 0 },@/ - { "version", 0, 0, 0 },@/ - { "interaction", 1, 0, 0 },@/ - { "mktex", 1, 0, 0 },@/ - { "no-mktex", 1, 0, 0 },@/ - { "kpathsea-debug", 1, 0, 0 },@/ - { "progname", 1, 0, 0 },@/ - { "fmt", 1, 0, 0 },@/ - { "output-directory", 1, 0, 0 },@/ - { "jobname", 1, 0, 0 },@/ - { "cnf-line", 1, 0, 0 },@/ - { "ini", 0, &iniversion, 1 },@/ - { "etex", 0, &etexp, 1 },@/ - { "parse-first-line", 0, &parsefirstlinep, 1 },@/ - { "no-parse-first-line", 0, &parsefirstlinep, 0 },@/ - { "file-line-error", 0, &filelineerrorstylep, 1 },@/ - { "no-file-line-error", 0, &filelineerrorstylep, 0 },@/ - { "compress", 0, &option_compress, 1 },@/ - { "no-empty-page", 0, &option_no_empty_page, 1 },@/ - { "empty-page", 0, &option_no_empty_page, 0 },@/ - { "hyphenate-first-word", 0, &option_hyphen_first, 1 },@/ - { "resolution", 1, 0, 0 },@/ - { "mfmode", 1, 0, 0 },@/ -#ifdef DEBUG - { "debug", 1, 0, 0 },@/ - { "hint-debug-help", 0, 0, 0 },@/ -#endif - { 0, 0, 0, 0 }@+}@+; - - -@ Parsing the command line options is accomplished with the -|parse_options| function which in turn uses the |getopt_long_only| -function from the \CEE/ library. This function returns 0 and sets the -|option_index| parameter to the option found, or it returns $-1$ if -the end of all options is reached. -@<k\TeX\ functions@>= -static void parse_options (int argc, char *argv[]) -{@+ while (true) { - int option_index; - int g = getopt_long_only (argc, argv, "+", long_options, &option_index); - if (g==0) - { @<handle the option at |option_index|@>@;@+ } - else if (g == -1) return; - } -} - -@ To handle the options, we compare the name at the given |option_index| with -the different option names. This is not a very efficient method, but the -impact is low and it's simple to write. - -Comparing the name of the argument with the |name| field in the |option| -structure is done in the auxiliar function |argument_is|. -Unfortunately the |name| field is in conflict with the |name| macro -defined by \TeX. To avoid the conflict, the |argument_is| function -goes just after the \.{kpathsea.h} header file that defines -the option structure. - - -@<Header files and function declarations@>= -#include <kpathsea/kpathsea.h> -static int argument_is(struct option *opt, char * s) -{@+ return STREQ(opt->name, s); @+} -#define ARGUMENT_IS(S) argument_is(long_options+option_index,S) - -@ Now we can handle the first two options: -@<handle the option at |option_index|@>= -if (ARGUMENT_IS("help")) usage_help(); -else if (ARGUMENT_IS("version")){@+ - printf("Version 0.0\n"); - exit(0);@+ -} - - -@ The ``interaction'' option sets \TeX's |interaction| variable -based on its string argument contained in the |optarg| variable. - -@<handle the option at |option_index|@>= -else @+if (ARGUMENT_IS ("interaction"))@t\2@> { - if (STREQ (optarg, "batchmode")) interaction = batch_mode; - else if (STREQ (optarg, "nonstopmode")) interaction = nonstop_mode; - else if (STREQ (optarg, "scrollmode")) interaction = scroll_mode; - else if (STREQ (optarg, "errorstopmode")) interaction = error_stop_mode; - else WARNING1 ("Ignoring unknown argument `%s' to --interaction", optarg); - } - -@ The next two options pass the string argument to the -\.{kpathsearch} library. - -@<handle the option at |option_index|@>= -else @+if (ARGUMENT_IS ("mktex")) @t\2@> kpse_maketex_option (optarg, true); -else if (ARGUMENT_IS ("no-mktex")) kpse_maketex_option (optarg, false); - - -@ To debug the searching done by the \.{kpathsearch} library, -the following otion can be used. -The argument value 3 is a good choice to start with. - -@<handle the option at |option_index|@>= -else @+if (ARGUMENT_IS ("kpathsea-debug")) @t\2@> - kpathsea_debug |= atoi (optarg); - - -@ The remaining options either set a flag and are handled by -the |getopt_long_only| function or they take a string argument -and assign it to the corresponding string variable. - -@<handle the option at |option_index|@>= -else @+if (ARGUMENT_IS ("progname"))@t\2@> - user_progname = normalize_quotes(optarg,"program name"); -else if (ARGUMENT_IS ("fmt")) - dump_name = normalize_quotes(optarg,"format name"); -else if (ARGUMENT_IS ("output-directory")) - output_directory = normalize_quotes(optarg,"output directory"); -else if (ARGUMENT_IS ("jobname")) - c_job_name = normalize_quotes (optarg, "job name"); -else @+if (ARGUMENT_IS ("cnf-line")) - add_cnf_line(optarg);@t\2@> -else if (ARGUMENT_IS("resolution")) @t\2@> -{ option_dpi_str=optarg; - option_dpi=strtol(option_dpi_str,NULL,10); -} -else if (ARGUMENT_IS("mfmode")) - option_mfmode=optarg; -#ifdef DEBUG@t\1@> -else @+if (ARGUMENT_IS("debug")) - debugflags=strtol(optarg,NULL,16); -else @+if (ARGUMENT_IS("hint-debug-help")) - hint_debug_help(); -#endif - -@ When string arguments specify files or directories, -special care is needed if arguments are quoted and/or contain spaces. -The function |normalize_quotes| makes shure that arguments containing -spaces get quotes around them and it checks for unballanced quotes. - - -@<k\TeX\ auxiliar functions@>= -static char *normalize_quotes (const char *nom, const char *mesg) -{@+ int quoted = false; - int must_quote = (strchr(nom, ' ') != NULL); - char *ret = xmalloc(strlen(nom)+3);/*room for two quotes and NUL*/ - char *p=ret; - const char *q; - - if (must_quote) - *p++ = '"'; - for (q = nom; *q; q++) - if (*q == '"') - quoted = !quoted;@+ - else - *p++ = *q; - - if (must_quote) - *p++ = '"'; - *p = '\0'; - if (quoted) { - fprintf(stderr, "! Unbalanced quotes in %s %s\n", mesg, nom); - exit(1); - } - return ret; -} - -@ With the \.{-cnf-line} option it is possible to specify -a line of text as if this line were part of \TeX's configuration -file---even taking precedence over conflicting lines in the configuration -file. For example it is possible to change \TeX's -\.{TEXINPUTS} variable by saying \.{--cnf-line=TEXINPUTS=/foo}. -The configuration lines are temporarily stored in the variable -|cnf_lines| and counted in |cnf_count| because we can send them -to the \.{kpathsearch} library only after the library has been -initialized sufficiently. - -@<Global...@>= -char **cnf_lines=NULL; -int cnf_count=0; - -@ The function |add_cnf_line| stores the -given command line argument in the variable |cnf_lines|. - -@<k\TeX\ auxiliar functions@>= -static void add_cnf_line(char *arg) -{@+ cnf_count++; - cnf_lines=xrealloc(cnf_lines,sizeof(char*)*cnf_count); - cnf_lines[cnf_count-1]=arg; -} - -@ To activate the configuration lines they are passed to the - \.{kpathsearch} library. - -@<activate configuration lines@>= -#if 0 /* this function does not exists allways */ -{@+ int i; - for (i=0;i<cnf_count;i++) - kpathsea_cnf_line_env_progname (kpse_def, cnf_lines[i]); - free(cnf_lines); -} -#endif - -@ After we are done with the options, -we inform the \.{kpathsearch} library about the program name. -This is an important piece of information for the library -because the library serves quite different programs -and its behaviour can be customized for each program -using configuration files. -After the program and engine name is set, -the library is ready to use. -@<set the program and engine name@>= -if (!user_progname) - user_progname = dump_name; -#if defined(WIN32) - if (user_progname) - kpse_reset_program_name (user_progname); -#else - kpse_set_program_name (argv[0], user_progname); -#endif - xputenv ("engine", "hitex");@/ - - -@ After the options, the command line usually continues with the name of the input -file. Getting a hold of the input file name can be quite complicated, -and we will have the first opportunity to use the \.{kpathsearch} library. - -We start by looking at the first argument after the options: -If it does not start with an -``\.{\AM}'' and neither with a ``\.{\BS}'', it's a simple file name. -Under Windows, however, filenames might start with a drive letter -followed by a colon and a ``\.{\BS}'' which is used to separate -directory names. Finally, if the filename is a quoted string, we need -to remove the quotes before we use the \.{kpathsearch} library to find it -and reattach the quotes afterwards. - -@<k\TeX\ auxiliar functions@>= -#ifdef WIN32 -static void clean_windows_filename(char *filename) -{@+if (strlen (filename) > 2 && isalpha (filename[0]) && - filename[1] == ':' && filename[2] == '\\') - { char *pp; - for (pp = filename; *pp; pp++) - if (*pp == '\\') - *pp = '/'; - } -} -#endif - -static char *find_file(char *fname, kpse_file_format_type t, int mx) -{@+char *filename; - int final_quote=(int)strlen(fname)-1; - int quoted = final_quote>1 && fname[0] == '"' && fname[final_quote]=='"'; - if (quoted) { - /* Overwrite last quote and skip first quote. */ - fname[final_quote] = '\0'; - fname++; - } - filename = kpse_find_file(fname, t, mx); - if (quoted) { - /* Undo modifications */ - fname--; - fname[final_quote] = '"'; - } - return filename; -} - -static char *get_input_file_name (void) -{@+ - char *input_file_name = NULL; - - if (argv[optind] && argv[optind][0] != '&' && argv[optind][0] != '\\') - { -#ifdef WIN32 - clean_windows_filename(argv[optind]); -#endif - argv[optind] = normalize_quotes(argv[optind], "input file"); - input_file_name=find_file(argv[optind],kpse_tex_format, false); - } - return input_file_name; -} - - -@ After we called |get_input_file_name|, we might need to look at |argv[argc-1]| -in case we run under Windows. - -@<set the input file name@>= - main_input_file = get_input_file_name (); - -#ifdef WIN32 - /* Were we given a simple filename? */ - if (main_input_file == NULL) { - char *file_name=argv[argc-1]; - if (file_name && file_name[0] != '-' && file_name[0] != '&' && file_name[0] != '\\') { - clean_windows_filename(file_name); - file_name = normalize_quotes(file_name, "argument"); - main_input_file=find_file(file_name,kpse_tex_format, false); - argv[argc-1] = file_name; - } - } -#endif - - -@ After we have an input file, we make an attempt at filling in options -from the {\tt texmf.cfg} file. - -@<set defaults from the {\tt texmf.cfg} file@>= - if (filelineerrorstylep < 0) - filelineerrorstylep = texmf_yesno ("file_line_error_style"); - if (parsefirstlinep < 0) - parsefirstlinep = texmf_yesno ("parse_first_line");@/@t~@> - -@ We needed: -@<k\TeX\ auxiliar functions@>= -static int texmf_yesno(const char *var) -{@+ - char *value = kpse_var_value (var); - return value && (*value == 't' || *value == 'y' || *value == '1'); -} - -@ We need a stack, matching the |line_stack| that -contains the source file names; -we postpone k\TeX\'s |full_source_filename_stack| to a later time. - -@<Global...@>= -int @!source_filename_stack0[max_in_open], *const @!source_filename_stack = @!source_filename_stack0-1; - -@ The function |print_file_line| -prints ``file:line:error'' style messages. It looks for a -filename in |source_filename_stack|, and if it fails to find -one falls back on the ``non-file:line:error'' style. - -@<Basic printing...@>= -static void print_file_line(void) -{@+int level=in_open; - while (level>0 && source_filename_stack[level]==0) level--; - if (level==0) print_nl("! "); - else - { print_nl(""); printn(source_filename_stack[level]); print_char(':'); - if (level==in_open) print_int(line); - else print_int(line_stack[level]); - print(": "); - } -} - -@ Most of the time \TeX\ is not running as \.{initex} or \.{virtex}, -but it runs with a format file preloaded. -To set the format name, we first check if the format name was given on the -command line with an ``\.{\AM}'' prefix, -second we might check the first line of the input file, -and last, we check if the program is an initex or virtex program. - -If we still don't have a format, -we use a plain format if running as a virtex, otherwise the program -name is our best guess. -There is no need to check for an extension, because the -\.{kpathsearch} library will take care of that. -We store the format file name in |dump_name| which is -used in the function |w_open_in| below. - -@<set the format name@>= -if (parsefirstlinep && !dump_name) - parse_first_line (main_input_file); -if (!main_input_file && argv[1] && argv[1][0] == '&') - dump_name = argv[1] + 1; -if (strcmp(kpse_program_name, "hinitex")==0) iniversion = true; -else if (strcmp(kpse_program_name, "hvirtex")==0 && !dump_name) - dump_name = "hitex"; -if (!dump_name) - dump_name = kpse_program_name; -if (!dump_name) -{ fprintf(stderr,"Unable to determine format name\n"); - exit(1); -} -if (etexp && !iniversion) -{ fprintf(stderr,"-etex requires -ini\n"); - exit(1); -} - -@ Here is the function |parse_first_line |. It searches the first line of -the file for a \TeX\ comment of the form ``\%\AM format''\footnote{${}^1$}{The idea of using this format came from Wlodzimierz Bzyl.}. -If found, we will use the format given there. - -@<k\TeX\ functions@>= -static void parse_first_line (char*filename) -{@+ FILE *f=NULL; - if (filename==NULL) return; - f = open_in(filename,kpse_tex_format,"r"); - if (f!=NULL) - { char *r,*s,*t=read_line (f); - xfclose (f, filename); - if (t==NULL) return; - s=t; - if (s[0] == '%' && s[1] == '&') { - s = s+2; - while ( ISBLANK(*s)) ++s; - r=s; - while (*s!=0 && *s!=' ' && *s!='\r' && *s!='\n') s++; - *s=0; - if (dump_name==NULL) { - char *f_name = concat (r, ".fmt"); - char *d_name = kpse_find_file (f_name,kpse_fmt_format, false); - if (d_name && kpse_readable_file (d_name)) { - dump_name = xstrdup (r); - kpse_reset_program_name (dump_name); - } - free (f_name); - } - } - free (t); - } -} - - -@ The \TeX\ Live infrastructure is able to generate format files, -font metric files, -and even some tex files, if required. - -@<enable the generation of input files@>= - kpse_set_program_enabled (kpse_tfm_format, MAKE_TEX_TFM_BY_DEFAULT, - kpse_src_compile);@/ - kpse_set_program_enabled (kpse_tex_format, MAKE_TEX_TEX_BY_DEFAULT, - kpse_src_compile);@/ - kpse_set_program_enabled (kpse_fmt_format, MAKE_TEX_FMT_BY_DEFAULT, - kpse_src_compile);@/ - kpse_set_program_enabled (kpse_pk_format, MAKE_TEX_PK_BY_DEFAULT, - kpse_src_compile);@/ - xputenv("MAKETEX_BASE_DPI", option_dpi_str); - xputenv("MAKETEX_MODE", option_mfmode); - - -@ In the old days, \TeX\ was a \PASCAL\ program, and standard \PASCAL\ -did say nothing about a command line. So \TeX\ would open the terminal -file for input and read all the information from the terminal. -If you don't give \TeX\ command line arguments, this is still true today. -In our present time, people got so much used to control the behaviour -of a program using command line arguments---especially when writing -scripts---that k\TeX\ allows the specification of commands on -the command line which \TeX\ would normally expect on -the first line of its terminal input. - -So our next task is -writing a function to add the remainder of the -command line to \TeX's input buffer. -The main job is done by the |input_add_str| function -which duplicates part of the |input_ln| function. -Further it skips initial spaces and replaces trailing spaces -and line endings by a single space. - -@<k\TeX\ auxiliar functions@>= -static void input_add_char(unsigned int c) -{@+ if (last >= max_buf_stack) - {@+max_buf_stack=last+1; - if (max_buf_stack==buf_size) - @<Report overflow of the input buffer, and abort@>; - } - buffer[last]=xord[c];incr(last); -} - -static void input_add_str(const char *str) -{@+ int prev_last; - while (*str==' ') str++; - prev_last=last; - while (*str!=0) - -input_add_char(*str++); - for (--last; last >= first ; --last) - { char c =buffer[last]; - if ((c) != ' ' && (c) != '\r' && (c) != '\n') break; - } - last++; - if (last>prev_last) input_add_char(' '); -} - -static int input_command_line(void) -{@+ -last=first; -while (optind < argc) input_add_str(argv[optind++]); -loc=first; -return (loc < last); -@+ } - - - -@ When we open an output file, there is usually no searching necessary. -In the best case, we have an absolute path and can open it. -If the path is relative, we try in this order: -the |file_name| prefixed by the |output_directory|, -the |file_name| as is, and -the |file_name| prefixed with the environment variable |TEXMFOUTPUT|. - -If we were successful with one of the modified names, we update -|name_of_file|. - -@<k\TeX\ functions@>= -FILE *open_out(const char *file_name, const char *file_mode) -{@+ FILE *f=NULL; - char *new_name=NULL; - int absolute = kpse_absolute_p(file_name, false); - if (absolute) - return fopen(file_name,file_mode); - if (output_directory) - { new_name = concat3(output_directory, DIR_SEP_STRING, file_name); - f = fopen(new_name,file_mode); - if (f==NULL) {@+ free(new_name); new_name=NULL;@+} - } - if (f==NULL) - f = fopen(file_name,file_mode); - if (f==NULL) - { const char *texmfoutput = kpse_var_value("TEXMFOUTPUT"); - if (texmfoutput!=NULL && texmfoutput[0]!=0) - { new_name = concat3(texmfoutput, DIR_SEP_STRING, file_name);@/ - f = fopen(new_name,file_mode); - if (f==NULL) {@+ free(new_name); new_name=NULL; @+} - } - } - if (f!=NULL && new_name!=NULL) - update_name_of_file(new_name,(int)strlen(new_name)); - if (new_name!=NULL) free(new_name); - return f; -} - -static bool a_open_out(alpha_file *f) - /*open a text file for output*/ -{@+f->f=open_out((char*)name_of_file+1,"w"); - return f->f!=NULL && ferror(f->f)==0;@+ -} - -static bool b_open_out(byte_file *f) - /*open a binary file for output*/ -{@+f->f=open_out((char *)name_of_file+1,"wb"); -return f->f!=NULL && ferror(f->f)==0;@+ -} - -#ifdef @!INIT -static bool w_open_out(word_file *f) - /*open a word file for output*/ -{@+f->f=open_out((char *)name_of_file+1,"wb"); - return f->f!=NULL && ferror(f->f)==0;@+ -} -#endif - -@ Format file names must be scanned -before \TeX's string mechanism has been initialized. -The function |update_name_of_file| will set |name_of_file| from -a \CEE/ string. - -We dare not give error messages here, since \TeX\ calls this routine before -the |error| routine is ready to roll. Instead, we simply drop excess characters, -since the error will be detected in another way when a strange file name -isn't found. -@^system dependencies@> - -@<k\TeX\ auxiliar functions@>= -static void update_name_of_file(char *@!s, int @!k) -{@+ int j; - if (k <= file_name_size) name_length=k;@+ - else name_length=file_name_size; - for (j=0; j<name_length;j++) name_of_file[j+1]=xchr[(int)s[j]]; - name_of_file[name_length+1]=0; -} - -@ In standard \TeX, the |reset| macro is used to open input files. -The \.{kpathsearch} library uses different search pathes for -different types of files and therefore different functions are needed to -open these files. The common code is in the function |open_in|. - - -@<k\TeX\ auxiliar functions@>= -static FILE*open_in(char*filename,kpse_file_format_type t,const char*rwb) -{@+ char *fname=NULL; - FILE*f= NULL; - fname= find_file(filename,t,true); - if(fname!=NULL) - {@+ - f= fopen(fname,rwb); - free(fname);@+ - } - return f; -} - -@ @<k\TeX\ functions@>= -static bool a_open_in(alpha_file *f) /*open a text file for input*/ -{@+f->f= open_in((char *)name_of_file+1,kpse_tex_format,"r"); - if (f->f!=NULL) get(*f); - return f->f!=NULL && ferror(f->f)==0; -} - -static bool b_open_in(byte_file *f) /*open a binary file for input*/ -{@+f->f= kpse_open_file((char *)name_of_file+1,kpse_tfm_format); - if (f->f!=NULL) get(*f); - return f->f!=NULL && ferror(f->f)==0; -} - - -@ \TeX's |open_fmt_file| function will call the following function -either with the name of a format file as given with an ``\.{\AM}'' -prefix in the input or with |NULL| if no such name was specified. -The function will try |dump_name| as a last resort before returning |NULL|. - - - -@<k\TeX\ functions@>= -static bool w_open_in(word_file *f) /*open a word file for input*/ -{@+ - f->f=NULL; - if (name_of_file[1]!=0) - f->f= open_in((char*)name_of_file+1,kpse_fmt_format,"rb"); - if (f->f!=NULL) get(*f); - return f->f!=NULL && ferror(f->f)==0; -} - -static bool open_fmt_file(void) -{@+int j=loc; - if (buffer[loc]=='&') - {@+incr(loc);j=loc;buffer[last]=' '; - while (buffer[j]!=' ') incr(j); - update_name_of_file((char *)buffer+loc,j-loc); - if (w_open_in(&fmt_file)) goto found; - } - update_name_of_file(dump_name,(int)strlen(dump_name)); - if (w_open_in(&fmt_file)) goto found; - name_of_file[1]=0; - wake_up_terminal; - wterm_ln("I can't find a format file!"); - return false; -found: loc=j;return true; -} - - - -@ All the code that we have seen so far commes together in the function |main_init| -which is the first function called in the main program of a \TeX\ engine -belonging to \TeX\ Live. Before doing so, we make copies of -argument count and argument vector putting them in global variables. -@<Global...@>= -static char **argv; -static int argc; - -@ @<k\TeX\ functions@>= -static void main_init(int ac, char *av[]) -{@+ - char* main_input_file; - argc = ac; - argv = av; - interaction = error_stop_mode;@/ - @<parse options@>@; - @<set the program and engine name@>@; - @<activate configuration lines@>@; - @<set the input file name@>@; - @<set defaults from the {\tt texmf.cfg} file@>@; - @<set the format name@>@; - @<enable the generation of input files@>@; -} - - -@ Before we can call the |parse_options| function, -we might need some special preparations for Windows. - -@<parse options@>= -#if defined(WIN32) -{@+ char* enc; - kpse_set_program_name (argv[0], NULL); - enc = kpse_var_value("command_line_encoding"); - get_command_line_args_utf8(enc, &argc, &argv);@/ - parse_options (argc, argv); -} -#else - parse_options (ac, av); -#endif - -@ Adding prototypes for the functions just defined allows \TeX\ -to call them. - -@<Header files and function declarations@>= - -static int input_command_line(void); -static void main_init(int ac, char *av[]); - -@ We conclude this chapter using \.{time.h} to provide a function -that is used to initialize -\TeX's date and time information. Because |time| is one of \TeX's -macros, we add the function |tl_now| that wraps the call to |time| -(and |gmtime|) for later use in |fix_date_and_time|. - -@<Header files and function declarations@>= -#include <time.h> -static struct tm *tl_now(void) -{@+ time_t t=time(NULL); - return gmtime(&t); -} - -@* Primitives required for \LaTeX. - -Still missing - -@* Index. -Here is where you can find all uses of each identifier in the program, -with underlined entries pointing to where the identifier was defined. -If the identifier is only one letter long, however, you get to see only -the underlined entries. {\sl All references are to section numbers instead of -page numbers.} - -This index also lists error messages and other aspects of the program -that you might want to look up some day. For example, the entry -for ``system dependencies'' lists all sections that should receive -special attention from people who are installing \TeX\ in a new -operating environment. A list of various things that can't happen appears -under ``this can't happen''. Approximately 40 sections are listed under -``inner loop''; these account for about 60\pct! of \TeX's running time, -exclusive of input and output. - -@ Generating the header file. -@(htex.h@>= -@h -enum {@+@<Constants in the outer block@>@+}; -@<Types in the outer block@>@; -extern void display_node(pointer p); -extern void hyphenate_word(void); -extern memory_word *const hfactor_eqtb, *const vfactor_eqtb; -extern scaled par_shape_hfactor, par_shape_vfactor; -extern scaled hhsize, hvsize; -extern int option_no_empty_page, option_hyphen_first; -extern int option_dpi; -extern FILE *open_out(const char *file_name, const char *file_mode); -extern void update_last_values(pointer p); /* see section~\secref{pagebuilder} */ -extern void print_err(char *s); -extern int s_no(const char *str); -extern two_halves *const hash; -extern scaled *const font_dsize; -extern scaled *const font_size; -extern void end_diagnostic(bool @!blank_line); -extern void show_box(pointer @!p); -extern void begin_diagnostic(void); -extern void short_display(int @!p); -extern int font_in_short_display; -extern int line; -extern int pack_begin_line; -extern void print_scaled(scaled @!s); -extern pointer new_null_box(void); -extern pointer new_rule(void); -extern void print_int(int @!n); -extern halfword badness(scaled @!t, scaled @!s); -extern str_number job_name; -extern pointer adjust_tail; -extern int *const depth_base; -extern int *const height_base; -extern int *const width_base; -extern int *const char_base; -extern scaled *const total_shrink; -extern scaled *const total_stretch; -extern int last_badness; -extern int dyn_used; -extern list_state_record nest[]; -extern void append_to_vlist(pointer @!b); -extern int nest_ptr; -extern void freeze_page_specs(small_number @!s); -extern pointer cur_p; -extern int r_hyf; -extern int l_hyf; -extern ASCII_code cur_lang; -extern void init_trie(void); -extern bool trie_not_ready; -extern void ship_out(pointer @!p); -extern void scan_left_brace(void); -extern void normal_paragraph(void); -extern void new_save_level(group_code @!c); -extern void begin_token_list(pointer @!p, quarterword @!t); -extern void push_nest(void); -extern void pop_nest(void); -extern int init_r_hyf; -extern int init_l_hyf; -extern ASCII_code init_cur_lang; -extern void delete_glue_ref(pointer @!p); -extern pointer new_param_glue(small_number @!n); -extern pointer new_penalty(int @!m); -extern scaled second_indent; -extern scaled second_width; -extern halfword last_special_line; -extern void line_break(int @!final_widow_penalty); -extern list_state_record cur_list; -extern void show_node_list(int @!p); -extern int depth_threshold; -extern int breadth_max; -extern void print_ln(void); -extern void free_node(pointer @!p, halfword @!s); -extern void flush_node_list(pointer @!p); -extern packed_ASCII_code str_pool[]; -extern pool_pointer str_start[]; -extern str_number *const font_name; -extern pointer new_character(internal_font_number @!f, eight_bits @!c); -extern int *const hyphen_char; -extern void delete_token_ref(pointer @!p); -extern pointer *const cur_mark; -extern memory_word *const eqtb; -extern memory_word font_info[]; -extern int *const param_base; -extern pointer new_spec(pointer @!p); -extern pointer new_glue(pointer @!q); -extern unsigned char *const name_of_file; -extern pointer new_disc(void); -extern pointer *const font_glue; -extern pointer copy_node_list(pointer @!p); -extern pointer get_node(int @!s); -extern pointer hi_mem_min; -extern int name_length; -extern void out_what(pointer @!p); -extern bool doing_leaders; -extern bool output_active; -extern int interaction; -extern memory_word *const mem; -extern int page_contents; -extern scaled page_so_far[]; -extern void end_graf(void); -extern void unsave(void); -extern void open_log_file(void); -extern void print_char(ASCII_code @!s); -extern void prompt_file_name(char *@!s, char *@!e); -extern void pack_job_name(char *@!s); -extern void print_spec(int @!p, char *@!s); -extern void pack_file_name(str_number @!n, char *@!a, char *@!e); -extern void print(char *@!s); -extern void print_nl(char *@!s); -extern void fatal_error(char *@!s); -extern void overflow(char *@!s, int @!n); -extern void confusion(char *@!s); -extern int main(int argc, char *argv[]); |