From e0c6872cf40896c7be36b11dcc744620f10adf1d Mon Sep 17 00:00:00 2001
From: Norbert Preining <norbert@preining.info>
Date: Mon, 2 Sep 2019 13:46:59 +0900
Subject: Initial commit

---
 web/c_cpp/cweb/cwebman.tex | 1763 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 1763 insertions(+)
 create mode 100644 web/c_cpp/cweb/cwebman.tex

(limited to 'web/c_cpp/cweb/cwebman.tex')

diff --git a/web/c_cpp/cweb/cwebman.tex b/web/c_cpp/cweb/cwebman.tex
new file mode 100644
index 0000000000..2e4ec65ea5
--- /dev/null
+++ b/web/c_cpp/cweb/cwebman.tex
@@ -0,0 +1,1763 @@
+% This file generates the user manual; TeX it, don't read it!
+% update 14 Nov 2016 by DEK: corrected obsolete remarks re debugging info
+
+\def\tangref{3} % where the main explanation of CTANGLing is given
+\input cwebmac
+\acrofalse\pdffalse\pdftexfalse
+\def\page{\box255 } \normalbottom
+\parskip 0pt plus 1pt
+\def\RA{\char'31 } % right arrow
+\def\hang{\hangindent 4em\ignorespaces}
+\font\eightrm=cmr8
+\font\ninerm=cmr9
+\font\ninett=cmtt9
+\font\eighttt=cmtt8
+\font\twelvett=cmtt12
+\font\quoterm=cmssq8
+\font\quoteit=cmssqi8
+\font\authorfont=cmr12
+\font\sectionfont=cmbx12
+
+\def\pb{\.{|...|}}
+\def\v{\.{\char'174}} % vertical (|) in typewriter font
+\def\lpile{\def\cr{\hfill\endline}\matrix} % I only use \lpile by itself
+\abovedisplayskip=.5\abovedisplayskip
+\belowdisplayskip=.5\belowdisplayskip
+\abovedisplayshortskip=.5\abovedisplayshortskip
+\belowdisplayshortskip=.5\belowdisplayshortskip
+\advance\baselineskip by -.5pt
+\advance\pageheight by \baselineskip % the manual just got a bit longer
+\advance\fullpageheight by \baselineskip
+\setpage
+
+\outer\def\section #1.{\penalty-500\bigskip
+        \centerline{\sectionfont\def\.##1{{\twelvett##1}} #1}\nobreak\vskip 6pt
+        \everypar{\hskip-\parindent\everypar{}}}
+
+\def\lheader{\mainfont\the\pageno\hfill\sc\runninghead\hfill}
+\def\rheader{\hfill\sc\runninghead\hfill\mainfont\the\pageno}
+\def\runninghead{{\tentt CWEB} USER MANUAL (VERSION 3.64)}
+
+% This verbatim mode assumes that ! marks are !! in the text being copied.
+\def\verbatim{\begingroup
+  \def\do##1{\catcode`##1=12 } \dospecials
+  \parskip 0pt \parindent 0pt \let\!=!
+  \catcode`\ =13 \catcode`\^^M=13
+  \tt \catcode`\!=0 \verbatimdefs \verbatimgobble}
+{\catcode`\^^M=13{\catcode`\ =13\gdef\verbatimdefs{\def^^M{\ \par}\let =\ }} %
+  \gdef\verbatimgobble#1^^M{}}
+
+\null\vfill
+\centerline{\titlefont The {\ttitlefont CWEB} System of
+    Structured Documentation}
+\vskip 18pt\centerline{(Version 3.64 --- February 2002)}
+\vskip 24pt
+\centerline{\authorfont Donald E. Knuth and Silvio Levy}
+\vfill
+
+\noindent
+\TeX\ is a trademark of the American Mathematical Society.
+
+\noindent
+Acrobat Reader is a trademark of Adobe Systems Incorporated.
+
+\bigskip\noindent
+The printed form of this manual is copyright \copyright\ 1994
+  by Addison-Wesley Publishing Company, Inc.  All rights reserved.
+\smallskip\noindent
+The electronic form is copyright \copyright\ 1987, 1990, 1993, 2000
+  by Silvio Levy and Donald E. Knuth.
+
+\bigskip\noindent
+Permission is granted to make and distribute verbatim copies of the
+electronic form of this document provided that the electronic copyright
+notice and this permission notice are preserved on all copies.
+
+\smallskip\noindent
+Permission is granted to copy and distribute modified versions of the
+electronic form of this document under the conditions for verbatim copying,
+provided that the entire resulting derived work is distributed under the terms
+of a permission notice identical to this one.
+
+\smallskip\noindent
+Individuals may make copies of the documentation from the electronic files
+for their own personal use.
+
+\smallskip\noindent
+Internet page \.{http://www-cs-faculty.stanford.edu/\char`\~knuth/cweb.html}
+contains current info about \.{CWEB} and related topics.
+
+\pageno=0 \titletrue\eject
+
+\titletrue
+\centerline{\titlefont The {\ttitlefont CWEB} System of
+    Structured Documentation}
+
+\vskip 15pt plus 3pt minus 3pt
+\centerline{\authorfont Donald E. Knuth and Silvio Levy}
+
+\vskip 24pt plus 3pt minus 3pt
+\noindent
+This document describes a version of Don Knuth's \.{WEB} system,
+adapted to \CEE/ by Silvio Levy.  Since its creation in 1987, \.{CWEB}
+has been revised and enhanced in various ways, by both Knuth and Levy.
+We now believe that its evolution is near an end; however, bug
+reports, suggestions and comments are still welcome, and
+should be sent to Levy (\.{levy@math.berkeley.edu}).
+
+Readers who are familiar with Knuth's memo ``The \.{WEB} System of Structured
+Documentation'' will be able
+to skim this material rapidly, because \.{CWEB} and \.{WEB} share
+the same philosophy and (essentially) the same syntax.  In some respects
+\.{CWEB} is a simplification
+of \.{WEB}: for example, \.{CWEB} does not need \.{WEB}'s features
+for macro definition and string handling, because \CEE/ and its
+preprocessor already take care of macros and strings. Similarly, the \.{WEB}
+conventions of denoting octal and hexadecimal constants by \.{@'77}
+and \.{@"3f} are replaced by \CEE/'s conventions \.{077} and
+\.{0x3f}. All other features of \.{WEB} have been
+retained, and new features have been added.
+
+We thank all who contributed suggestions and criticism to
+the development of \.{CWEB}. We are especially grateful to Steve
+Avery, Nelson Beebe, Hans-Hermann Bode, Klaus Guntermann, Norman Ramsey,
+Joachim Schnitter, and Saroj Mahapatra,
+who contributed code, and to Cameron Smith, who
+made many suggestions improving the manual.  Ramsey has made
+literate programming accessible to users of yet other languages by means of
+his \.{SPIDER} system [see {\sl Communications of the ACM\/ \bf32} (1989),
+1051--1055]. The book {\sl Literate Programming\/} by Knuth (1992) contains
+a comprehensive bibliography of related early work.
+Bode, Schnitter, and Mahapatra adapted \.{CWEB} so that it works
+for \CPLUSPLUS/ as well; therefore in the text below you can read \CPLUSPLUS/
+for \CEE/ if you so desire.
+
+\section Introduction.
+The philosophy behind \.{CWEB} is
+that programmers who want to provide the best
+possible documentation for their programs need two things
+simultaneously:  a language like \TEX/ for formatting, and a language like
+\CEE/ for programming. Neither type of language can provide the
+best documentation by itself. But when both are appropriately combined, we
+obtain a system that is much more useful than either language separately.
+
+The structure of a software program may be thought of as a ``web'' that is
+made up of many interconnected pieces. To document such a program, we want
+to explain each individual part of the web and how it relates to its
+neighbors. The typographic tools provided by \TEX/ give us an opportunity
+to explain the local structure of each part by making that structure
+visible, and the programming tools provided by \CEE/ make it possible
+for us to specify the algorithms formally and unambiguously. By combining
+the two, we can develop a style of programming that maximizes our ability
+to perceive the structure of a complex piece of software, and at the same
+time the documented programs can be mechanically translated into a working
+software system that matches the documentation.
+
+The \.{CWEB} system consists of two programs named \.{CWEAVE} and \.{CTANGLE}.
+When writing a \.{CWEB} program the user keeps the
+\CEE/ code and the documentation in the same file, called the \.{CWEB}
+file and generally named \.{something.w}.  The command
+`\.{cweave} \.{something}' creates an output file \.{something.tex}, which
+can then be fed to \TEX/, yielding a ``pretty printed'' version of
+\.{something.w} that correctly handles
+typographic details like page layout and the use of indentation,
+italics, boldface, and mathematical symbols. The typeset output also
+includes extensive cross-index
+information that is gathered automatically.  Similarly, if you run the
+command `\.{ctangle} \.{something}' you will get a \CEE/ file \.{something.c},
+which can then be compiled to yield executable code.
+
+Besides providing a documentation tool, \.{CWEB} enhances the \CEE/
+language by providing the
+ability to permute pieces of the program text, so that a large system can
+be understood entirely in terms of small sections and their local
+interrelationships.  The \.{CTANGLE} program is so named because it takes a
+given web and moves the sections from their web structure into the order
+required by \CEE/; the advantage of programming in \.{CWEB} is that the
+algorithms can be expressed in ``untangled'' form, with each section
+explained separately.  The \.{CWEAVE} program is so named because it takes
+a given web and intertwines the \TEX/ and \CEE/ portions contained in
+each section, then it knits the whole fabric into a structured document.
+(Get it? Wow.)  Perhaps there is some deep connection here with the fact
+that the German word for ``weave'' is ``{\it webe\/}'', and the
+corresponding Latin imperative is ``{\it texe\/}''!
+
+A user of \.{CWEB} should be fairly familiar with the \CEE/
+programming language.  A minimal amount of acquaintance with \TEX/ is also
+desirable, but in fact it can be acquired as one uses \.{CWEB}, since
+straight text can be typeset in \TEX/ with virtually no knowledge of
+that language.  To someone familiar with both \CEE/ and \TEX/ the amount of
+effort necessary to learn the commands of \.{CWEB} is small.
+
+\section Overview.
+Two kinds of material go into \.{CWEB} files: \TEX/ text and \CEE/ text.
+A programmer writing in \.{CWEB} should be thinking both of the
+documentation and of the \CEE/ program being created;
+i.e., the programmer should be instinctively aware of the different
+actions that \.{CWEAVE} and \.{CTANGLE} will perform on the \.{CWEB} file.
+\TEX/ text is essentially copied without change by \.{CWEAVE}, and it is
+entirely deleted by \.{CTANGLE}; the \TEX/ text is ``pure
+documentation.'' \CEE/ text, on the other hand, is formatted by
+\.{CWEAVE} and it is shuffled around by \.{CTANGLE}, according to rules that
+will become clear later. For now the important point to keep in mind is
+that there are two kinds of text. Writing \.{CWEB} programs is something
+like writing \TEX/ documents, but with an additional ``\CEE/ mode''
+that is added to \TEX/'s horizontal mode, vertical mode, and math mode.
+
+A \.{CWEB} file is built up from units called {\sl sections\/} that are more
+or less self-contained.  Each section has three parts:
+
+\yskip\item{$\bullet$} A \TEX/ part, containing explanatory material about what
+is going on in the section.
+
+\item{$\bullet$} A middle part, containing macro definitions that serve as
+abbreviations for \CEE/ constructions that would be less comprehensible
+if written out in full each time. They are turned by \.{CTANGLE} into
+preprocessor macro definitions.
+
+\item{$\bullet$} A \CEE/ part, containing a piece of the program that
+\.{CTANGLE} will produce. This \CEE/ code should ideally be about a
+dozen lines long, so that it is easily comprehensible as a unit and so
+that its structure is readily perceived.
+
+\yskip\noindent The three parts of each section must appear in this order;
+i.e., the \TEX/ commentary must come first, then the middle part, and
+finally the \CEE/ code. Any of the parts may be empty.
+
+A section begins with either of the symbols `\.{@\ }' or `\.{@*}', where
+`\.{\ }' denotes a blank space. A section ends
+at the beginning of the next section (i.e., at the next
+`\.{@\ }' or `\.{@*}'), or at the end of the file, whichever comes first.
+The \.{CWEB} file may also contain material that is not part of any section
+at all, namely the text (if any) that occurs before the first section.
+Such text is said to be ``in limbo''; it is ignored by \.{CTANGLE}
+and copied essentially verbatim by \.{CWEAVE}, so its function is to
+provide any additional formatting instructions that may be desired in the
+\TEX/ output. Indeed, it is customary to begin a \.{CWEB} file with
+\TEX/ code in limbo that loads special fonts, defines special macros,
+changes the page sizes, and/or produces a title page.
+
+Sections are numbered consecutively, starting with 1. These numbers appear
+at the beginning of each section of the \TEX/ documentation output by
+\.{CWEAVE}, and they appear
+as bracketed comments at the beginning and end of the code generated by that
+section in the \CEE/ program output by \.{CTANGLE}.
+
+\section Section Names.
+Fortunately, you never mention these numbers yourself when you are writing
+in \.{CWEB}. You just say `\.{@\ }' or `\.{@*}' at the beginning of each
+new section, and the numbers are supplied automatically by \.{CWEAVE} and
+\.{CTANGLE}. As far as you are concerned, a section has a
+{\sl name\/} instead of a number; its name is specified by writing
+`\.{@<}' followed by \TEX/ text followed by `\.{@>}'. When \.{CWEAVE}
+outputs a section name, it replaces the `\.{@<}' and `\.{@>}' by
+angle brackets and inserts the section number in small type. Thus, when you
+read the output of \.{CWEAVE} it is easy to locate any section that is
+referred to in another section.
+
+For expository purposes, a section name should be a good description of the
+contents of that section; i.e., it should stand for the abstraction
+represented by the section. Then the section can be ``plugged into'' one or
+more other sections in such a way
+that unimportant details of its inner workings
+are suppressed.  A section name therefore ought to be long enough to convey
+the necessary meaning.
+
+Unfortunately, it is laborious to type
+such long names over and over again, and it is also difficult to specify a
+long name twice in exactly the same way so that \.{CWEAVE} and \.{CTANGLE}
+will be able to match the names to the sections. To ameliorate this situation,
+\.{CWEAVE} and \.{CTANGLE} let you abbreviate a section name, so long as
+the full name appears somewhere in the \.{CWEB} file; you can type simply
+`\.{@<$\alpha$...@>}', where $\alpha$ is any string that is a prefix of
+exactly one section name appearing in the file. For example, `\.{@<Clear
+the arrays@>}' can be abbreviated to `\.{@<Clear...@>}' if no other section
+name begins with the five letters `\.{Clear}'.  Elsewhere
+you might use the abbreviation `\.{@<Clear t...@>}', and so on.
+
+Section names must otherwise match character for character, except
+that consecutive characters of white space (spaces, tab marks, newlines, and/or
+form feeds) are treated as equivalent to a single space, and such spaces are
+deleted at the beginning and end of the name. Thus, `\.{@< Clear { }the
+arrays @>}' will also match the name in the previous example.
+Spaces following the ellipsis in abbreviations are ignored as well, but
+not those before, so that `\.{@<Clear t ...@>}' would not match
+`\.{@<Clear the arrays@>}'.
+
+\section What \.{CTANGLE} Does.
+We have said that a section begins with `\.{@\ }' or `\.{@*}', but we
+didn't say how it gets divided up into a \TEX/ part, a middle part,
+and a \CEE/ part. The middle part begins with the first appearance of
+`\.{@d}' or `\.{@f}' in the section, and the \CEE/ part begins with
+the first appearance of `\.{@c}' or `\.{@<section name@>=}'.  In the
+latter case you are saying, in effect, that the section name stands
+for the \CEE/ text that follows. Alternatively, if the \CEE/ part
+begins with `\.{@c}' instead of a section name, the current section is
+said to be {\sl unnamed}.
+
+The construct `\.{@<section name@>}' can appear
+any number of times in the \CEE/ part of a section:
+Subsequent appearances indicate that a named section is being
+``used'' rather than ``defined.'' In other words, the
+\CEE/ code for the named section, presumably defined elsewhere, should be
+spliced in at this point in the \CEE/ program.  Indeed,
+the main idea of \.{CTANGLE} is to make a \CEE/ program out of
+individual sections, named and unnamed.  The exact way in which this is done
+is this: First all the macro definitions
+indicated by `\.{@d}' are turned into \CEE/ preprocessor macro definitions
+and copied at the beginning.
+Then the \CEE/ parts of unnamed sections are copied down,
+in order; this constitutes the first-order
+approximation to the text of the program. (There should be at least
+one unnamed section, otherwise there will be no program.) Then all section
+names that appear in the first-order approximation are replaced by the \CEE/
+parts of the corresponding sections, and this substitution process
+continues until no section names remain. All comments are removed, because
+the \CEE/ program is intended only for the eyes of the \CEE/ compiler.
+
+If the same name has been given to more than one section, the \CEE/ text
+for that name is obtained by putting together all of the \CEE/ parts in
+the corresponding sections. This feature is useful, for example, in a
+section named `Global variables', since one can then
+declare global variables in whatever sections those variables are
+introduced. When several sections have the same name, \.{CWEAVE} assigns the
+first section number as the number corresponding to that name, and it
+inserts a note at the bottom of that section telling the reader to `See
+also sections so-and-so'; this footnote gives the numbers of all the other
+sections having the same name as the present one. The \CEE/ text
+corresponding to a section is usually formatted by \.{CWEAVE} so that the
+output has an equivalence sign in place of the equals sign in the \.{CWEB}
+file; i.e., the output says `$\langle\,$section
+name$\,\rangle\equiv\null$\CEE/ text'. However, in the case of the second
+and subsequent appearances of a section with the same name, this `$\equiv$'
+sign is replaced by `$\mathrel+\equiv$', as an indication that the
+following \CEE/ text is being appended to the \CEE/ text of another section.
+
+As \.{CTANGLE} enters and leaves sections, it inserts preprocessor
+\.{\#line} commands into the \CEE/ output file.  This means that
+when the compiler gives you error messages, or when you debug your program,
+the messages refer to line numbers in the \.{CWEB} file, and not in the
+\CEE/ file.  In most cases you can therefore
+forget about the \CEE/ file altogether.
+
+\section What \.{CWEAVE} Does.
+The general idea of \.{CWEAVE} is to make a \.{.tex} file from the \.{CWEB}
+file in the following way: The first line of the \.{.tex} file
+tells \TEX/ to input a file with macros that
+define \.{CWEB}'s documentation conventions. The next lines of the file
+will be copied from whatever \TEX/ text is in limbo before the first
+section.  Then comes the output for each section in turn, possibly
+interspersed with end-of-page marks.  Finally, \.{CWEAVE} will generate a
+cross-reference index that lists each section number in which each \CEE/
+identifier appears, and it will also generate an alphabetized list
+of the section names, as well as a table of contents that
+shows the page and section numbers for each ``starred'' section.
+
+What is a ``starred'' section, you ask? A section that begins with `\.{@*}'
+instead of `\.{@\ }' is slightly special in that it denotes a new major
+group of sections. The `\.{@*}' should be followed by the title of this
+group, followed by a period. Such sections will always start on a new page
+in the \TEX/ output, and the group title will appear as a running headline
+on all subsequent pages until the next starred section. The title will also
+appear in the table of contents, and in boldface type at the beginning of
+its section. Caution:  Do not use \TEX/ control sequences in such titles,
+unless you know that the \.{cwebmac} macros will do the right thing with
+them. The reason is that these titles are converted to uppercase when
+they appear as running heads, and they are converted to boldface when they
+appear at the beginning of their sections, and they are also written out to
+a table-of-contents file used for temporary storage while \TEX/ is
+working; whatever control sequences you use must be meaningful in all
+three of these modes.
+
+The \TEX/ output produced by \.{CWEAVE} for each section consists of
+the following: First comes the section number (e.g., `\.{\\M123.}'
+at the beginning of section 123, except that `\.{\\N}' appears in place of
+`\.{\\M}' at the beginning of a starred section). Then comes the
+\TEX/ part of the section, copied almost verbatim except as noted
+below. Then comes the middle part and the \CEE/ part, formatted
+so that there will be a little extra space between them if both are
+nonempty. The middle and \CEE/ parts are obtained by inserting
+a bunch of funny-looking \TEX/ macros into the \CEE/ program; these
+macros handle typographic details about fonts and proper math spacing,
+as well as line breaks and indentation.
+
+\section C Code in \TEX/ Text and Vice Versa.
+When you are typing \TEX/ text, you will probably want to make frequent
+reference to variables and other quantities in your \CEE/ code, and you
+will want those variables to have the same typographic treatment
+when they appear in your text as when they appear in your
+program.  Therefore the \.{CWEB} language allows you to get the effect of
+\CEE/ editing within \TEX/ text, if you place `\.|' marks before and
+after the \CEE/ material. For example, suppose you want to say something
+like this:
+$$\hbox{ If \\{pa} is declared as `\&{int} ${}{*}\\{pa}$',
+the assignment $\\{pa}\K{\AND}\|a[\T{0}]$ makes \\{pa}
+point to the zeroth element of \|a.}$$
+The \TEX/ text would look like this in your \.{CWEB} file:
+$$\lpile{\.{If |pa| is declared as `|int *pa|', the}\cr
+\.{assignment |pa=\&a[0]| makes |pa| point
+to the zeroth element of |a|.}\cr}$$
+And \.{CWEAVE} translates this into something you are glad you didn't have
+to type:
+$$\lpile{\.{If \\\\\{pa\} is declared as
+  `\\\&\{int\} \$\{\}\{*\}\\\\\{pa\}\$',}\cr
+\.{the assignment \$\\\\\{pa\}\\K\{\\AND\}\\|a[\\T\{0\}]\$}\cr
+\.{makes \\\\\{pa\} point to the zeroth element of \\|a.}\cr}$$
+Incidentally, the cross-reference index that \.{CWEAVE} would make, in
+the presence of a comment like this, would include
+the current section number as one of the index entries for \\{pa},
+even though \\{pa} might not appear in the \CEE/ part of
+this section. Thus, the index covers references to identifiers in
+the explanatory comments as well as in the program itself; you will
+soon learn to appreciate this feature. However, the identifiers
+\&{int} and \|a\ would not be indexed,
+because \.{CWEAVE} does not make index entries for reserved words or
+single-letter identifiers. Such identifiers are felt to be so ubiquitous
+that it would be pointless to mention every place where they occur.
+
+Although a section begins with \TEX/ text and ends with \CEE/ text, we
+have noted that the dividing line isn't sharp, since \CEE/ text can be
+included in \TEX/ text if it is enclosed in `\pb'.  Conversely, \TEX/ text
+appears frequently within \CEE/ text, because everything in
+comments (i.e., between \.{/*} and \.{*/}, or following \.{//})
+is treated as \TEX/ text.
+Likewise, the text of a section name consists of \TEX/ text, but
+the construct \.{@<section name@>} as a whole is expected to be found
+in \CEE/ text; thus, one typically goes back and forth
+between the \CEE/ and \TEX/ environments in a natural way, as in these
+examples:
+$$
+\displaylines{
+\hbox{\.{if} \.{(x==0)} \.{@<Empty} \.{the} \.{|buffer|} \.{array@>}} \cr
+\hbox{\.{...} \.{using}  \.{the} \.{algorithm}
+\.{in} \.{|@<Empty} \.{the} \.{|buffer|} \.{array@>|.}} }
+$$
+The first of these excerpts
+would be found in the \CEE/ part of a section, into which the code
+from the section
+named ``Empty the \\{buffer} array'' is being spliced. The second excerpt
+would be found in the \TEX/ part of the section, and the named section
+is being ``cited'', rather than defined or used.
+(Note the `\pb' surrounding the section name in this case.)
+
+\section Macros.
+The control code \.{@d} followed by
+$$\\{identifier}\.{ }\hbox{\CEE/ text}\qquad\hbox{or by}\qquad
+\\{identifier}\.(\\{par}_1,\ldots,\\{par}_n\.{) }\hbox{\CEE/ text}$$
+(where there is no blank between the
+\\{identifier} and the parentheses in the second case) is
+transformed by \.{CTANGLE} into a preprocessor command, starting with
+\.{\#define}, which is printed at the top of the \CEE/ output file
+as explained earlier.
+
+A `\.{@d}' macro definition can go on for several lines, and the
+newlines don't have to be protected by backslashes, since \.{CTANGLE}
+itself inserts the backslashes.   If
+for any reason you need a \.{\#define} command at a specific spot in
+your \CEE/ file, you can treat it as \CEE/ code, instead of as a
+\.{CWEB} macro; but then you do have to protect newlines yourself.
+
+\section Strings and constants.
+If you want a string to appear in the \CEE/ file, delimited by pairs of
+\.' or \." marks as usual, you can type it exactly so in the \.{CWEB} file,
+except that the character `\.@' should be typed `\.{@@}' (it becomes a
+control code, the only one that can appear in strings; see below).
+Strings should end on the same line as they begin, unless there's a
+backslash at the end of lines within them.
+
+\TEX/ and \CEE/ have different ways to refer to octal and hex constants,
+because \TEX/ is oriented to technical writing while \CEE/ is oriented to
+computer processing.  In \TEX/ you
+make a constant octal or hexadecimal by prepending \.' or \.",
+respectively, to it; in \CEE/ the constant should be preceded by \.0
+or \.{0x}.  In \.{CWEB} it seems reasonable to let each convention hold
+in its respective realm; so in \CEE/ text you get $40_8$ by typing
+`\.{040}', which \.{CTANGLE} faithfully copies into the \CEE/ file (for
+the compiler's benefit) and which \.{CWEAVE} prints as $\T{\~40}$.
+Similarly, \.{CWEAVE} prints the hexadecimal \CEE/ constant `\.{0x20}'
+as \T{\^20}. The use of italic font for octal digits and typewriter font
+for hexadecimal digits makes the meaning of such constants clearer in
+a document. For consistency, then, you
+should type `\.{|040|}'  or `\.{|0x20|}'
+in the \TEX/ part of the section.
+
+\section Control codes.
+A \.{CWEB} {\sl control code\/}
+is a two-character combination of which the first is `\.@'.
+We've already seen the meaning of several control codes; it's time to
+list them more methodically.
+
+In the following list,
+the letters in brackets after a control code indicate in what contexts that
+code is allowed.  $L$ indicates that the code is allowed in limbo; $T$
+(for \TEX/), $M$ (for middle), and $C$ (for \CEE/) mean that the code is
+allowed in each of the three parts of a section, at top level---that
+is, outside such constructs as `\pb' and section names.  An arrow $\to$
+means that the control code terminates the present part of the \.{CWEB}
+file, and inaugurates the part indicated by the letter following the
+arrow.  Thus $[LTMC\to T]$ next to \.{@\ } indicates that this control
+code can occur in limbo, or in any of the three parts of a section, and
+that it starts the (possibly empty) \TEX/ part of the following section.
+
+Two other abbreviations can occur in these brackets: The letter $r$ stands for
+{\it restricted context}, that is, material inside \CEE/ comments, section
+names, \CEE/ strings and control texts (defined below); the letter
+$c$ stands for {\it inner \CEE/ context}, that is, \CEE/ material
+inside `\pb' (including `\pb's inside comments, but not those
+occurring in other restricted contexts).  An asterisk $*$ following
+the brackets means
+that the context from this control code to the matching \.{@>} is
+restricted.
+
+Control codes involving letters are case-insensitive; thus \.{@d} and
+\.{@D} are equivalent. Only the lowercase versions are mentioned
+specifically below.
+
+\gdef\@#1[#2] {\penalty-50\yskip\hangindent 2em\noindent\.{@#1\unskip
+  \spacefactor1000{ }}$[#2]$\quad}
+\def\more{\hangindent 2em \hangafter0}
+\def\subsec{\penalty-300\medskip\noindent}
+
+\@@ [LTMCrc] A double \.@ denotes the single character `\.@'. This is
+the only control code that is legal everywhere.
+Note that you must use this convention if you are giving an internet
+email address in a \.{CWEB} file (e.g., \.{levy@@math.berkeley.edu}).
+
+\subsec
+Here are the codes that introduce the \TEX/ part of a section.
+
+\@\ [LTMC\to T] This denotes the beginning of a new (unstarred)
+section. A tab mark or form feed or
+end-of-line character is equivalent to a space when it follows an \.@
+sign (and in most other cases).
+
+\@* [LTMC\to T] This denotes the beginning of a new starred
+section, i.e., a section that begins a new major group. The title of the new
+group should appear after the \.{@*}, followed by a period. As explained
+above, \TEX/ control sequences should be avoided in such titles unless
+they are quite simple. When \.{CWEAVE} and \.{CTANGLE} read a \.{@*}, they
+print an asterisk on the terminal
+followed by the current section number, so that the user
+can see some indication of progress. The very first section should be starred.
+
+\more You can specify the ``depth'' of a starred section by typing \.* or a
+decimal number after the \.{@*}; this indicates the relative ranking
+of the current group of sections in the program hierarchy. Top-level
+portions of the program, introduced by \.{@**}, get their names typeset
+in boldface type in the table of contents; they are said to have
+depth~$-1$. Otherwise the depth is a nonnegative number, which governs
+the amount of indentation on the contents page. Such indentation helps
+clarify the structure of a long program. The depth is assumed to be 0
+if it is not specified explicitly; when your program is short, you
+might as well leave all depths zero.  A starred section always begins
+a new page in the output, unless the depth is greater than~1.
+
+\subsec
+The middle part of each section consists of any number of
+macro definitions (beginning with \.{@d}) and format definitions (beginning
+with \.{@f} or \.{@s}), intermixed in any order.
+
+\@d [TM\to M] Macro definitions begin with \.{@d}, followed by
+an identifier and optional parameters and \CEE/ text as explained earlier.
+
+\@f [TM\to M] Format definitions begin with \.{@f}; they cause
+\.{CWEAVE} to treat identifiers in a special way when they appear in
+\CEE/ text. The general form of a format definition is `\.{@f} \|l
+\|r', followed by an optional comment enclosed between
+\.{/*} and \.{*/}, where \|l and \|r
+are identifiers; \.{CWEAVE} will subsequently treat identifier \|l as it
+currently treats \|r. This feature allows a \.{CWEB} programmer to invent
+new reserved words and/or to unreserve some of \CEE/'s reserved
+identifiers. For example, the common words `error' and `line'
+have been given a special meaning in the \CEE/ preprocessor,
+so \.{CWEAVE} is set up to format them specially; if you want a variable
+named \\{error} or \\{line}, you should say
+$$\.{@f error normal}\qquad\qquad\.{@f line normal}$$
+somewhere in your program.
+
+\more If \|r is the special identifier `\\{TeX}', identifier \|l
+will be formatted as a \TEX/ control sequence; for example,
+`\.{@f foo TeX}' in the \.{CWEB} file will cause identifier \\{foo} to
+be output as \.{\\foo} by \.{CWEAVE}. The programmer should define
+\.{\\foo} to have whatever custom format is desired, assuming \TEX/
+math mode. (Each underline
+character is converted to \.{x} when making the \TEX/ control sequence,
+and each dollar sign is converted to~\.X;
+thus \\{foo\_bar} becomes \.{\\fooxbar}. Other characters, including digits,
+are left untranslated, so \TEX/ will consider them as macro parameters,
+not as part of the control sequence itself. For example,
+$$\.{\\def\\x\#1\{x\_\{\#1\}\} @f x1 TeX @f x2 TeX}$$
+will format \.{x1} and \.{x2} not as \\{x1} and \\{x2} but as $x_1$ and $x_2$.)
+
+\more If \|r is the special identifier `\\{make\_pair}', identifier \|l will
+be treated as a \CPLUSPLUS/ function template. For example, after
+\.{@f}~\.{convert}~\.{make\_pair} one can say `\.{convert<int>(2.5)}' without
+having \.< and \.> misunderstood as less-than and greater-than signs.
+
+\more \.{CWEAVE} knows that identifiers being
+defined with a \&{typedef} should become reserved words; thus you
+don't need format definitions very often.
+
+\@s [TM\to M;\;L] Same as \.{@f}, but \.{CWEAVE} does not show the format
+definition in the output, and the optional \CEE/ comment is not
+allowed. This is used mostly in \.{@i} files.
+
+\subsec
+Next come the codes that govern the \CEE/ part of a section.
+
+\@{c @p} [TM\to C] The \CEE/ part of an unnamed section begins with \.{@c}
+(or with \.{@p} for ``program''; both control codes do the same thing).
+This causes \.{CTANGLE} to append the following \CEE/ code
+to the first-order program text, as explained on page~\tangref.
+Note that \.{CWEAVE} does not print a `\.{@c}' in the \TEX/
+output, so if you are creating a \.{CWEB} file based on a \TEX/-printed
+\.{CWEB} documentation you have to remember to insert \.{@c} in the
+appropriate places of the unnamed sections.
+
+\@< [TM\to C;\; C;\; c] $*$ This control code introduces a
+section name (or unambiguous prefix, as discussed above), which
+consists of \TEX/ text and extends to the matching \.{@>}.
+The whole construct \.{@<...@>} is conceptually a \CEE/ element.
+The behavior is different depending on the context:
+
+\more A \.{@<} appearing in contexts $T$ and $M$ attaches the
+following section name to the current section, and inaugurates the
+\CEE/ part of the section.  The closing \.{@>} should be followed by
+\.{=} or \.{+=}.
+
+\more
+In context $C$, \.{@<} indicates that the named
+section is being used---its \CEE/ definition is spliced in by
+\.{CTANGLE}, as explained on page~\tangref.
+As an error-detection measure,
+\.{CTANGLE} and \.{CWEAVE} complain if such a section name is followed
+by \.=, because most likely this is meant as the definition of a new
+section, and so should be preceded by \.{@\ }.  If you really want to
+say $\langle\,$foo$\,\rangle=\\{bar}$, where $\langle\,$foo$\,\rangle$
+is being used and not defined, put a newline before the \.=.
+
+\more
+Finally, in inner \CEE/ context (that is, within `\pb' in the \TEX/ part
+of a section or in a comment), \.{@<...@>}
+means that the named section is being
+cited.  Such an occurrence is ignored by \.{CTANGLE}. Note that
+even here we think of the section name as being a \CEE/ element, hence the \pb.
+
+\@( [TM\to C;\;C;\;c] $*$ A section name can begin with \.{@(}.
+Everything works just as for \.{@<}, except that the \CEE/ code
+of the section named \.{@(foo@>} is written by \.{CTANGLE}
+to file \.{foo}. In this way you can get multiple-file output from
+a single \.{CWEB} file. (The \.{@d} definitions are not output
+to such files, only to the master \.{.c} file.) One use of this feature
+is to produce header files for other program modules that will be loaded
+with the present one. Another use is to produce a test routine that
+goes with your program. By keeping the sources for a program and its
+header and test routine together, you are more likely to keep
+all three consistent with each other. Notice that the output of a named
+section can be incorporated in several different output files, because
+you can mention \.{@<foo@>} in both \.{@(bar1@>} and \.{@(bar2@>}.
+
+\@h [Cc] Causes \.{CTANGLE}
+to insert at the current spot the \.{\#define} statements
+from the middle parts of all sections,
+and {\it not\/} to write them at the beginning of the \CEE/ file.
+Useful when you want the macro definitions to come after the include files,
+say. (Ignored by \.{CTANGLE} inside `\pb'.)
+
+\subsec
+The next several control codes introduce ``control
+texts,'' which end with the next `\.{@>}'.  The closing `\.{@>}' must be on
+the same line of the \.{CWEB} file as the line where the control text began.
+The context from each of these control codes to the matching \.{@>} is
+restricted.
+
+\@\^ [TMCc] $*$ The control text that follows, up to the next
+`\.{@>}', will be entered into the index together with the identifiers of
+the \CEE/ program; this text will appear in roman type. For example, to
+put the phrase ``system dependencies'' into the index that is output by
+\.{CWEAVE}, type
+`\.{@\^system dependencies@>}' in each section
+that you want to index as system dependent.
+
+\@. [TMCc] $*$ The control text that follows will be entered into the index
+in \.{typewriter} \.{type}.
+
+\@: [TMCc] $*$ The control text that follows will be entered into the index
+in a format controlled by the \TEX/ macro `\.{\\9}', which you
+should define as desired.
+
+\@t [MCc] $*$ The control text that follows will
+be put into a \TEX/ \.{\\hbox} and formatted along with the neighboring
+\CEE/ program. This text is ignored by \.{CTANGLE}, but it can be used
+for various purposes within \.{CWEAVE}. For example, you can make comments
+that mix \CEE/ and classical mathematics, as in `$\\{size}<2^{15}$', by
+typing `\.{|size < 2@t\$\^\{15\}\$@>|}'.
+
+\@= [MCc] $*$ The control text that follows will
+be passed verbatim to the \CEE/ program.
+
+\@q [LTMCc] $*$ The control text that follows will
+be totally ignored---it's a comment for readers of the \.{CWEB} file only.
+A file intended to be included in
+limbo, with \.{@i}, can identify itself with \.{@q} comments.
+Another use is to balance unbalanced parentheses in \CEE/ strings,
+so that your text editor's parenthesis matcher doesn't go into a tailspin.
+
+\@! [TMCc] $*$
+The section number in an index entry will be underlined if `\.{@!}'
+immediately precedes the identifier or control text being indexed. This
+convention is used to distinguish the sections where an identifier is
+defined, or where it is explained in some special way, from the sections
+where it is used. A~reserved word or an identifier of length one will not
+be indexed except for underlined entries. An `\.{@!}' is implicitly inserted
+by \.{CWEAVE} when an identifier is being defined or declared in \CEE/
+code; for example, the definition
+$$\hbox{\&{int} \\{array}[\\{max\_dim}], \\{count}${}=\\{old\_count};$}$$
+makes the names \\{array} and \\{count} get an underlined entry in the
+index.  Statement labels, function definitions like
+\\{main}(\&{int}~\\{argc},\,\&{char}~$*$\\{argv}[\,]),
+and \&{typedef} definitions also
+imply underlining. An old-style
+function definition (without prototyping) doesn't define its arguments;
+the arguments will, however, be considered to be defined
+(i.e., their index entries will be underlined) if their types are
+declared before the body of the function in the usual way
+(e.g., `\&{int}~\\{argc}; \&{char}~${*}\\{argv}[\,]$; $\{\,\ldots\,\}$').
+Thus \.{@!} is not needed very often, except in unusual constructions
+or in cases like
+$$\.{enum boolean \{@!false, @!true\};}$$
+here \.{@!} gives the best results because individual constants enumerated
+by \.{enum} are not automatically underlined in the index at their
+point of definition.
+
+\subsec
+We now turn to control codes that affect only the operation of
+\.{CTANGLE}.
+
+\@' [MCc] This control code is dangerous because it has quite different
+meanings in \.{CWEB} and the original \.{WEB}. In \.{CWEB} it produces the
+decimal constant corresponding to the ASCII code for a string of length~1
+(e.g., \.{@'a'} is \.{CTANGLE}d into \.{97} and \.{@'\\t'} into
+\.9). You might want to use this if you need to work in ASCII on a
+non-ASCII machine; but in most cases the \CEE/ conventions of
+\.{<ctype.h>} are adequate for character-set-independent programming.
+
+\@\& [MCc] The \.{@\&} operation causes whatever is on its left to be
+adjacent to whatever is on its right, in the \CEE/ output. No spaces or
+line breaks will separate these two items.
+
+\@l [L] \.{CWEB} programmers have the option of using any 8-bit character
+code from the often-forbidden range 128--255 within \TEX/ text; such
+characters are also permitted in strings and even in identifiers of the
+\CEE/ program.
+Under various extensions of the basic
+ASCII standard, the higher 8-bit codes correspond
+to accented letters, letters from non-Latin alphabets,
+and so on. When such characters occur in identifiers, \.{CTANGLE} must replace
+them by standard ASCII alphanumeric characters or
+\.{\_}, in order to generate legal \CEE/ code.  It does this by means
+of a transliteration table, which by default associates the string
+\.{Xab} to the character with ASCII code \T{\^}$ab$ (where $a$ and $b$ are
+hexadecimal digits, and $a\ge8$).  By placing the
+construction \.{@l\ ab\ newstring} in limbo, you are telling
+\.{CTANGLE} to replace this character by \.{newstring} instead.
+For example, the ISO Latin-1 code for the letter `\"u' is \T{\^FC}
+(or \.{'\char`\\374'}),
+and \.{CTANGLE} will normally change this code to the
+three-character sequence \.{XFC} if it
+appears in an identifier. If you say \.{@l} \.{fc} \.{ue}, the code will
+be transliterated into \.{ue} instead.
+
+\more
+\.{CWEAVE} passes 8-bit characters straight through to \TEX/ without
+transliteration; therefore \TEX/ must be prepared to receive them.
+If you are formatting all your nonstandard identifiers as ``custom''
+control sequences, you should
+make \TEX/ treat all their characters as letters. Otherwise you should either
+make your 8-bit codes ``active'' in \TEX/, or load fonts that
+contain the special characters you need in the correct positions.
+(The font selected by \TEX/ control sequence \.{\\it} is used for
+identifiers.)
+Look for special macro packages designed for \.{CWEB} users in your language;
+or, if you are brave, write one yourself.
+
+\subsec
+The next eight control codes (namely `\.{@,}', `\.{@/}', `\.{@|}', `\.{@\#}',
+`\.{@+}', `\.{@;}', `\.{@[}', and `\.{@]}') have no effect on the \CEE/
+program output by \.{CTANGLE}; they merely help to improve the readability
+of the \TEX/-formatted \CEE/ that is output by \.{CWEAVE}, in unusual
+circumstances. \.{CWEAVE}'s built-in formatting method is fairly good
+when dealing with syntactically correct \CEE/ text, but
+it is incapable of handling all possible cases, because it must deal with
+fragments of text involving macros and section names; these fragments do
+not necessarily obey \CEE/'s syntax. Although \.{CWEB} allows you to
+override the automatic formatting, your best strategy is not to worry
+about such things until you have seen what \.{CWEAVE} produces automatically,
+since you will probably need to make only a few corrections when you are
+touching up your documentation.
+
+\@, [MCc] This control code inserts a thin space in \.{CWEAVE}'s output.
+Sometimes you need this extra space if you are using
+macros in an unusual way, e.g., if two identifiers are adjacent.
+
+\@/ [MC] This control code causes a line break to occur within a \CEE/
+program formatted by \.{CWEAVE}. Line breaks
+are chosen automatically by \TEX/ according to a scheme that works 99\%\
+of the time, but sometimes you will prefer to force a line break so that
+the program is segmented according to logical rather than visual
+criteria. If a comment follows, say `\.{@/@,}' to break the line
+before the comment.
+
+\@| [MC] This control code specifies an optional line break in the midst of
+an expression. For example, if you have
+a long expression on the right-hand side of an assignment
+statement, you can use `\.{@|}' to specify breakpoints more logical than
+the ones that \TEX/ might choose on visual grounds.
+
+\@\# [MC] This control code forces a line break, like \.{@/} does,
+and it also causes a little extra white space to appear between the lines at
+this break. You might use it, for example,
+between groups of macro definitions that are logically separate but within
+the same section. \.{CWEB} automatically inserts this extra space
+between functions, between external declarations and functions, and
+between declarations and statements within a function.
+
+\@+ [MC] This control code cancels a line break that might otherwise be
+inserted by \.{CWEAVE}, e.g., before the word `\&{else}', if you want to
+put a short if--else construction on a single line.
+If you say `\.{\{@+}' at the beginning of a compound statement
+that is the body of a function, the first declaration or
+statement of the function will appear on the same line as the
+left brace, and it will be indented by the same amount as the
+second declaration or statement on the next line.
+
+\@; [MC] This control code is treated like a semicolon, for formatting
+purposes, except that it is invisible. You can use it, for example, after
+a section name or macro when the \CEE/ text represented by that section or macro
+is a compound statement or ends
+with a semicolon. Consider constructions like
+$$\lpile{\.{if (condition) macro @;}\cr
+\.{else break;}\cr}$$
+where \\{macro} is defined to be a compound statement (enclosed in braces).
+This is a well-known infelicity of \CEE/ syntax.
+
+\@{[} [MC] See \.{@]}.
+
+\@] [MC] Place \.{@[...@]} brackets around program text that \.{CWEAVE} is
+supposed to format as an expression, if it doesn't already do so. (This
+occasionally applies to unusual macro arguments.) Also
+insert `\.{@[@]}' between a simple type name and a left parenthesis
+when declaring a pointer to a function, as in
+$$\.{int @[@] (*f)();}$$
+otherwise \.{CWEAVE} will confuse the first part of that declaration with
+the \CPLUSPLUS/ expression `\&{int}($*f$)'. Another example, for people
+who want to use low-level \.{\#define} commands in the midst of \CEE/ code
+and the definition begins with a cast:
+$$\.{\#define foo @[(int)(bar)@]}$$
+
+\subsec
+The remaining control codes govern the input that \.{CWEB} sees.
+
+\@{x @y @z}[\\{change\_file}]
+\.{CWEAVE} and \.{CTANGLE} are designed to work with two input files,
+called \\{web\_file} and \\{change\_file}, where \\{change\_file} contains
+data that overrides selected portions of \\{web\_file}. The resulting merged
+text is actually what has been called the \.{CWEB} file elsewhere in this
+report.
+
+\more Here's how it works: The change file consists of zero or more ``changes,''
+where a change has the form `\.{@x}$\langle$old lines$\rangle$\.{@y}$\langle$%
+new lines$\rangle$\.{@z}'. The special control codes \.{@x}, \.{@y}, \.{@z},
+which are allowed only in change files, must appear at the beginning of a line;
+the remainder of such a line is ignored.
+The $\langle$old lines$\rangle$ represent material that exactly matches
+consecutive lines of the \\{web\_file}; the $\langle$new lines$\rangle$
+represent zero or more lines that are supposed to replace the old. Whenever
+the first ``old line'' of a change is found to match a line in the
+\\{web\_file}, all the other lines in that change must match too.
+
+\more Between changes, before the first change, and after the last change,
+the change file can have any number of lines that do not begin with
+`\.{@x}', `\.{@y}', or~`\.{@z}'. Such lines are bypassed and not used for
+matching purposes.
+
+\more This dual-input feature is useful when working with a master \.{CWEB}
+file that has been received from elsewhere (e.g., \.{tangle.w} or
+\.{weave.w} or \.{tex.web}), when changes are desirable to customize the
+program for your local computer system. You will be able to debug your
+system-dependent changes without clobbering the master web file; and once
+your changes are working, you will be able to incorporate them readily
+into new releases of the master web file that you might receive from time
+to time.
+
+\@i [\\{web\_file}]
+Furthermore the \\{web\_file} itself can be a combination of
+several files.  When either \.{CWEAVE} or \.{CTANGLE} is reading a file and
+encounters the control code \.{@i} at the beginning of a line, it
+interrupts normal reading and starts looking at the file named after the
+\.{@i}, much as the \CEE/ preprocessor does when it encounters an \.{\#include}
+line.  After the included file has been entirely read, the program
+goes back to the next line
+of the original file.  The file name following \.{@i} can be
+surrounded by \." characters, but such delimiters are
+optional. Include files can nest.
+
+\more
+Change files can have lines starting with \.{@i}. In this way
+you can replace one included file with another. Conceptually, the
+replacement mechanism described above does its work first, and
+its output is then checked for \.{@i} lines. If \.{@i} \.{foo}
+occurs between \.{@y} and \.{@z} in a change file, individual lines
+of file \.{foo} and files it includes are not changeable; but changes
+can be made to lines from files that were included by unchanged input.
+
+\more On \UNIX/ systems (and others that support environment variables),
+if the environment variable \.{CWEBINPUTS} is set, or if the compiler flag
+of the same name was defined at compile time,
+\.{CWEB} will look for include files in the directory thus named, if
+it cannot find them in the current directory.
+
+\section Additional features and caveats.
+
+1. In certain installations of \.{CWEB} that
+{\def\\#1#2{`{\tentex\char'#1#2}'}%
+have an extended character set, the characters
+\\13, \\01, \\31, \\32, \\34, \\35,
+\\36, \\37, \\04, \\20, and \\21}
+can be typed as abbreviations for `\.{++}', `\.{--}', `\.{->}',
+`\.{!=}', `\.{<=}', `\.{>=}', `\.{==}', `\.{\v\v}', `\.{\&\&}',
+`\.{<<}', and `\.{>>}',
+respectively.
+
+2. If you have an extended character set, you can use it with only minimal
+restrictions, as discussed under the rules for \.{@l} above. But you should
+stick to standard ASCII characters if you want to write programs that will
+be useful to all the poor souls out there who don't have extended
+character sets.
+
+3. The \TEX/ file output by \.{CWEAVE} is broken into lines having at most
+80 characters each. When
+\TEX/ text is being copied, the existing line breaks are copied as well.
+If you aren't doing anything too tricky, \.{CWEAVE} will recognize when
+a \TEX/ comment is being split across two or more lines, and it will
+append `\.\%' to the beginning of such continued comments.
+
+4. \CEE/ text is translated by a ``bottom up'' procedure that
+identifies each token as a ``part of speech'' and combines parts of speech
+into larger and larger phrases as much as possible according to a special
+grammar that is explained in the documentation of \.{CWEAVE}. It is easy to
+learn the translation scheme for simple constructions like single
+identifiers and short expressions, just by looking at a few examples of
+what \.{CWEAVE} does, but the general mechanism is somewhat complex because
+it must handle much more than \CEE/ itself. Furthermore the output
+contains embedded codes that cause \TEX/ to indent and break lines as
+necessary, depending on the fonts used and the desired page width. For
+best results it is wise to avoid enclosing long \CEE/ texts in \pb, since the
+indentation and line breaking codes are omitted when the \pb\ text is
+translated from \CEE/ to \TEX/. Stick to simple expressions or
+statements.  If a \CEE/ preprocessor command is enclosed in \pb,
+the \.\# that introduces it must be at the beginning of a line,
+or \.{CWEAVE} won't print it correctly.
+
+5. Comments are not permitted in \pb\ text. After a `\.|'
+signals the change from \TEX/ text to \CEE/ text, the next `\.|' that is
+not part of a string or control text or section name ends the \CEE/ text.
+
+6. A comment must have properly nested occurrences of left and right
+braces, otherwise \.{CWEAVE} will complain. But it
+does try to balance the braces, so that \TEX/ won't foul up too much.
+
+7. When you're debugging a program and decide to omit some of your
+\CEE/ code, do NOT simply ``comment it out.'' Such comments are not
+in the spirit of \.{CWEB} documentation; they will appear to readers
+as if they were explanations of the uncommented-out instructions.
+Furthermore, comments of a program must be valid \TEX/ text; hence
+\.{CWEAVE} will get confused if you enclose \CEE/ statements in
+\.{/*...*/} instead of in \.{/*|...|*/}.  If you must comment out
+\CEE/ code, you can surround it with preprocessor commands
+like \.{\#if 0==1} and \.{\#endif}.
+
+8. The \.{@f} feature allows you to define one identifier to act like
+another, and these format definitions are carried out sequentially.
+In general, a given identifier has only one printed format
+throughout the entire document, and this format is used even before
+the \.{@f} that defines it. The reason is that \.{CWEAVE} operates in two
+passes; it processes \.{@f}'s and cross-references on the first pass and
+it does the output on the second.  (However, identifiers that
+implicitly get a boldface format, thanks to a \.{typedef} declaration,
+don't obey this rule; they are printed differently before and after
+the relevant \.{typedef}.  This is unfortunate, but hard to fix. You can
+get around the restriction by saying, say, `\.{@s} \.{foo} \.{int}',
+before or after the \.{typedef}.)
+
+9. Sometimes it is desirable to insert spacing into formatted \CEE/ code that
+is more general than the thin space provided by `\.{@,}'. The \.{@t} feature
+can be used for this purpose; e.g., `\.{@t\\hskip 1in@>}' will
+leave one inch of blank space. Furthermore, `\.{@t\\4@>}' can be
+used to backspace by one unit of indentation, since the control sequence
+\.{\\4} is defined in \.{cwebmac} to be such a backspace. (This
+control sequence is used, for example, at the beginning of lines that
+contain labeled statements, so that the label will stick out a little at
+the left.) You can also use `\.{@t\}\\3\{-5@>}' to force a break
+in the middle of an expression.
+
+10. Each identifier in \.{CWEB} has a single formatting convention. Therefore
+you shouldn't use the same identifier to denote, say, both a type name and
+part of a \.{struct}, even though \CEE/ does allow this.
+
+\section Running the programs.
+The \UNIX/ command line for \.{CTANGLE} is
+$$\.{ctangle [options] web\_file[.w] [\{change\_file[.ch]|-\} [out\_file]]}$$
+and the same conventions apply to \.{CWEAVE}. If `\.-' or no change file is
+specified, the change file is null. The extensions \.{.w} and \.{.ch}
+are appended only if the given file names contain no dot. If the
+web file defined in this way cannot be found, the extension \.{.web}
+will be tried. For example, `\.{cweave} \.{cob}' will try to read
+\.{cob.w}; failing that, it will try \.{cob.web} before giving up.
+If no output file name is specified, the name of the \CEE/ file output by
+\.{CTANGLE} is obtained by appending the extension \.{.c};
+the name of the \TEX/ file output by \.{CWEAVE} gets the extension \.{.tex}.
+Index files output by \.{CWEAVE} replace \.{.tex} by \.{.idx} and \.{.scn}.
+
+Programmers who like terseness might choose to set up their
+ operating shell so that `\.{wv}' expands to
+`\.{cweave -bhp}'; this will suppress most terminal output from \.{CWEAVE}
+except for error messages.
+
+Options are introduced either by a \.- sign, to turn an option off,
+or by a \.+ sign to turn one on. For example, `\.{-fb}' turns off
+options \.f and \.b; `\.{+s}' turns on option \.s. Options can be
+specified before the file names, after the file names, or both. The following
+options are currently implemented:
+
+\yskip
+\def\option#1 {\textindent{\.#1}\hangindent2\parindent}
+
+\option b Print a banner line at the beginning of execution. (On
+by default.)
+
+\option e Enclose \CEE/ material formatted by \.{CWEAVE} in
+brackets \.{\\PB\{...\}}, so that special hooks can be used.
+(Off by default; has no effect on \.{CTANGLE}.)
+
+\option f Force line breaks after each \CEE/ statement formatted
+by \.{CWEAVE}. (On by default; \.{-f} saves paper but looks less \CEE/-like
+to some people.) (Has no effect on \.{CTANGLE}.)
+
+\option h Print a happy message at the conclusion of a successful
+run. (On by default.)
+
+\option p Give progress reports as the program runs. (On by default.)
+
+\option s Show statistics about memory usage after the program
+runs to completion. (Off by default.)
+If you
+have large \.{CWEB} files or sections, you may need to see
+how close you come to exceeding the capacity of \.{CTANGLE} and/or \.{CWEAVE}.
+
+\option x Include indexes and a table of contents in the \TEX/ file
+output by \.{CWEAVE}. (On by default.) (Has no effect on \.{CTANGLE}.)
+
+\section Further details about formatting.
+You may not like the way \.{CWEAVE} handles certain
+situations. If you're desperate, you can customize \.{CWEAVE}
+by changing its grammar.  This means changing the source code,
+a task that you might find amusing. A table of grammar rules
+appears in the \.{CWEAVE} source listing, and you can make a separate
+copy of that table by copying the file \.{prod.w} found in the \.{CWEB}
+sources and saying `\.{cweave}~\.{-x}~\.{prod}', followed by
+`\.{tex}~\.{prod}'.
+
+You can see exactly
+how \.{CWEAVE} is parsing your \CEE/ code by preceding
+it with the line `\.{@ @c @2}'. (The control code `\.{@2}'
+turns on a ``peeping'' mode, and `\.{@0}' turns it off.)
+For example, if you run \.{CWEAVE} on the file
+\medskip
+\begingroup
+\verbatim
+@ @c @2
+main (argc,argv)
+char **argv;
+{ for (;argc>0;argc--) printf("%s\n",argv[argc-1]); }
+!endgroup
+\endgroup
+\medskip\noindent
+you get the following gibberish on your screen:
+\medskip
+\begingroup
+\verbatim
+[...]
+14:*exp +(+ exp...
+11:*exp +exp+ raw...
+10:*+exp+ raw +ubinop?+...
+[...]
+60: +fn_decl+*+{+ -stmt- +}-
+55:*+fn_decl+ -stmt-
+52:*+function-
+[...]
+!endgroup
+\endgroup
+\medskip
+The first line says that grammar rule 14 has just been applied, and \.{CWEAVE}
+currently has in its memory a sequence of chunks of \TEX/ code (called
+``scraps'') that are respectively
+of type \\{exp} (for expression), open-parenthesis,
+\\{exp} again, close-parenthesis, and further scraps that haven't yet
+been considered by the parser.  (The \.+ and \.- signs stipulate that
+\TEX/ should be in or out of math mode at the scrap boundaries. The \.* shows
+the parser's current position.)
+Then rule 11 is applied, and
+the sequence $(\,exp\,)$ becomes an \\{exp} and so on.  In the
+end the whole \CEE/ text has become one big scrap of type \\{function}.
+
+Sometimes things don't work as smoothly, and you get a bunch of
+lines lumped together.  This means that \.{CWEAVE} could not
+digest something in your \CEE/ code.  For instance, suppose
+`\.{@<Argument definitions@>}' had appeared instead of
+`\.{char **argv;}' in the program above. Then \.{CWEAVE} would have
+been somewhat mystified, since it thinks that section names
+are just \\{exp}s.  Thus it would tell \TEX/ to format
+`\X2:Argument declarations\X' on the same line as
+`$\\{main}(\\{argc},\39\\{argv}{}$)'.
+In this case you should help \.{CWEAVE} by putting `\.{@/}' after
+`\.{main(argc,argv)}'.
+
+\.{CWEAVE} automatically inserts a bit of extra space between declarations
+and the first apparent statement of a block. One way to defeat this
+spacing locally is
+$$\vbox{\halign{#\hfil\cr
+\.{int x;@+@t\}\\6\{@>}\cr
+\.{@<Other locals@>@;@\#}\cr}}$$
+the `\.{@\#}' will put extra space after `$\langle\,$Other locals$\,\rangle$'.
+
+\section Hypertext and hyperdocumentation.
+
+Many people have of course noticed analogies between \.{CWEB} and the
+World Wide Web. The \.{CWEB} macros are in fact set up so that the output of
+\.{CWEAVE} can be converted easily into Portable Document Format,
+with clickable hyperlinks that can be read with Adobe's Acrobat Reader,
+using a widely available open-source program called \.{dvipdfm} developed
+by Mark~A. Wicks. After using \.{CWEAVE} to convert \.{cob.w} into
+\.{cob.tex}, you can prepare and view a hypertext version of the program
+by giving the commands
+$$\vbox{\halign{\.{#}\hfil\cr
+tex "\\let\\pdf+ \\input cob"\cr
+dvipdfm cob\cr
+acroread cob.pdf\cr}}$$
+instead of invoking \TeX\ in the normal way. (Thanks to Hans Hagen,
+C\'esar Augusto Rorato Crusius, and Julian Gilbey
+for the macros that make this work.)
+Alternatively, thanks to H\`an Th\^e\kern-.3em\raise.3ex\hbox{\'{}} Th\`anh
+and Andreas Scherer, you can generate \.{cob.pdf} in one step by simply
+saying `\.{pdftex}~\.{cob}'.
+
+A more elaborate system called \.{CTWILL}, which extends the usual cross
+references of \.{CWEAVE} by preparing links from the uses of identifiers
+to their definitions, is also available---provided that you are willing
+to work a bit harder in cases where an identifier is multiply defined.
+\.{CTWILL} is intended primarily for hardcopy output, but its principles
+could be used for hypertext as well.
+See Chapter 11 of {\sl Digital Typography\/} by D.~E. Knuth (1999), and
+the program sources at \.{ftp://ftp.cs.stanford.edu/pub/ctwill}.
+
+\section Appendices.
+
+As an example of a real program written in \.{CWEB}, Appendix~A
+contains an excerpt from the \.{CWEB} program itself.  The reader who
+examines the listings in this appendix carefully will get a good
+feeling for the basic ideas of \.{CWEB}.
+
+Appendix B is the file that sets \TEX/ up to accept
+the output of \.{CWEAVE}, and Appendix~C discusses how to use some of those
+macros to vary the output formats.
+
+A ``long'' version of this manual, which can be produced from the \.{CWEB}
+sources via the \UNIX/ command \.{make} \.{fullmanual}, also contains
+appendices D, E, and~F, which exhibit the complete source code for
+\.{CTANGLE} and \.{CWEAVE}.
+
+\vfil\eject\titletrue
+
+\def\runninghead{APPENDIX A --- {\tentt CWEB} FILE FORMAT}
+\section Appendix A: Excerpts from a \.{CWEB} Program.
+
+This appendix consists
+of four listings.  The first shows the \.{CWEB} input that
+generated sections 12--15 of the file \.{common.w}, which contains
+routines common to \.{CWEAVE} and \.{CTANGLE}.
+Note that some of the lines are indented to show the program structure;
+the indentation is ignored by \.{CWEAVE} and \.{CTANGLE}, but users find
+that \.{CWEB} files are quite readable if they have some such indentation.
+
+The second and third listings
+show corresponding parts
+of the \CEE/ code output by \.{CTANGLE} and of
+the corresponding \TEX/ code output by \.{CWEAVE}, when run on \.{common.w}.
+The fourth listing shows how that output looks when printed out.
+
+\vskip 6pt
+\begingroup \def\tt{\eighttt} \baselineskip9pt
+\verbatim
+@ Procedure |prime_the_change_buffer|
+sets |change_buffer| in preparation for the next matching operation.
+Since blank lines in the change file are not used for matching, we have
+|(change_limit==change_buffer && !!changing)| if and only if
+the change file is exhausted. This procedure is called only when
+|changing| is 1; hence error messages will be reported correctly.
+
+@c
+void
+prime_the_change_buffer()
+{
+  change_limit=change_buffer; /* this value is used if the change file ends */
+  @<Skip over comment lines in the change file; |return| if end of file@>;
+  @<Skip to the next nonblank line; |return| if end of file@>;
+  @<Move |buffer| and |limit| to |change_buffer| and |change_limit|@>;
+}
+
+@ While looking for a line that begins with \.{@@x} in the change file, we
+allow lines that begin with \.{@@}, as long as they don't begin with \.{@@y},
+\.{@@z}, or \.{@@i} (which would probably mean that the change file is fouled up).
+
+@<Skip over comment lines in the change file...@>=
+while(1) {
+  change_line++;
+  if (!!input_ln(change_file)) return;
+  if (limit<buffer+2) continue;
+  if (buffer[0]!!='@@') continue;
+  if (xisupper(buffer[1])) buffer[1]=tolower(buffer[1]);
+  if (buffer[1]=='x') break;
+  if (buffer[1]=='y' || buffer[1]=='z' || buffer[1]=='i') {
+    loc=buffer+2;
+    err_print("!! Missing @@x in change file");
+@.Missing @@x...@>
+  }
+}
+
+@ Here we are looking at lines following the \.{@@x}.
+
+@<Skip to the next nonblank line...@>=
+do {
+  change_line++;
+  if (!!input_ln(change_file)) {
+    err_print("!! Change file ended after @@x");
+@.Change file ended...@>
+    return;
+  }
+} while (limit==buffer);
+
+@ @<Move |buffer| and |limit| to |change_buffer| and |change_limit|@>=
+{
+  change_limit=change_buffer-buffer+limit;
+  strncpy(change_buffer,buffer,limit-buffer+1);
+}
+
+!endgroup
+\endgroup
+\vfill\eject
+
+\def\runninghead{APPENDIX A  --- TRANSLATION BY {\tentt CTANGLE}}
+
+Here's the portion of the \CEE/ code generated by \.{CTANGLE} that corresponds
+to the source on the preceding page.  Notice that sections~13, 14 and~15
+have been tangled into section~12.
+
+\vskip6pt
+\begingroup \def\tt{\eighttt} \baselineskip9pt
+\verbatim
+/*:9*//*12:*/
+#line 247 "common.w"
+
+void
+prime_the_change_buffer()
+{
+change_limit= change_buffer;
+/*13:*/
+#line 261 "common.w"
+
+while(1){
+change_line++;
+if(!!input_ln(change_file))return;
+if(limit<buffer+2)continue;
+if(buffer[0]!!='@')continue;
+if(xisupper(buffer[1]))buffer[1]= tolower(buffer[1]);
+if(buffer[1]=='x')break;
+if(buffer[1]=='y'||buffer[1]=='z'||buffer[1]=='i'){
+loc= buffer+2;
+err_print("!! Missing @x in change file");
+
+}
+}
+
+/*:13*/
+#line 252 "common.w"
+;
+/*14:*/
+#line 278 "common.w"
+
+do{
+change_line++;
+if(!!input_ln(change_file)){
+err_print("!! Change file ended after @x");
+
+return;
+}
+}while(limit==buffer);
+
+/*:14*/
+#line 253 "common.w"
+;
+/*15:*/
+#line 288 "common.w"
+
+{
+change_limit= change_buffer-buffer+limit;
+strncpy(change_buffer,buffer,limit-buffer+1);
+}
+
+/*:15*/
+#line 254 "common.w"
+;
+}
+
+/*:12*//*16:*/
+!endgroup
+\endgroup
+\vfill\eject
+
+\def\runninghead{APPENDIX A --- TRANSLATION BY {\tentt CWEAVE}}
+
+Here is the corresponding excerpt from \.{common.tex}.
+
+\vskip6pt
+\begingroup \def\tt{\eighttt} \baselineskip9pt
+\verbatim
+\M{12}Procedure \PB{\\{prime\_the\_change\_buffer}}
+sets \PB{\\{change\_buffer}} in preparation for the next matching operation.
+Since blank lines in the change file are not used for matching, we have
+\PB{$(\\{change\_limit}\E\\{change\_buffer}\W\R\\{changing})$} if and only if
+the change file is exhausted. This procedure is called only when
+\PB{\\{changing}} is 1; hence error messages will be reported correctly.
+!vskip-.5!baselineskip
+\Y\B\&{void} \\{prime\_the\_change\_buffer}(\,)\1\1\2\2\6
+${}\{{}$\1\6
+${}\\{change\_limit}\K\\{change\_buffer}{}$;\C{ this value is used if the
+change file ends }\6
+\X13:Skip over comment lines in the change file; \PB{\&{return}} if end of file%
+\X;\6
+\X14:Skip to the next nonblank line; \PB{\&{return}} if end of file\X;\6
+\X15:Move \PB{\\{buffer}} and \PB{\\{limit}} to \PB{\\{change\_buffer}} and %
+\PB{\\{change\_limit}}\X;\6
+\4${}\}{}$\2\par
+\fi
+!vskip-.5!baselineskip
+\M{13}While looking for a line that begins with \.{@x} in the change file, we
+allow lines that begin with \.{@}, as long as they don't begin with \.{@y},
+\.{@z}, or \.{@i} (which would probably mean that the change file is fouled
+up).
+!vskip-.5!baselineskip
+\Y\B\4\X13:Skip over comment lines in the change file; \PB{\&{return}} if end
+of file\X${}\E{}$\6
+\&{while} (\T{1})\5
+${}\{{}$\1\6
+${}\\{change\_line}\PP;{}$\6
+\&{if} ${}(\R\\{input\_ln}(\\{change\_file})){}$\1\5
+\&{return};\2\6
+\&{if} ${}(\\{limit}<\\{buffer}+\T{2}){}$\1\5
+\&{continue};\2\6
+\&{if} ${}(\\{buffer}[\T{0}]\I\.{'@'}){}$\1\5
+\&{continue};\2\6
+\&{if} (\\{xisupper}(\\{buffer}[\T{1}]))\1\5
+${}\\{buffer}[\T{1}]\K\\{tolower}(\\{buffer}[\T{1}]);{}$\2\6
+\&{if} ${}(\\{buffer}[\T{1}]\E\.{'x'}){}$\1\5
+\&{break};\2\6
+\&{if} ${}(\\{buffer}[\T{1}]\E\.{'y'}\V\\{buffer}[\T{1}]\E\.{'z'}\V\\{buffer}[%
+\T{1}]\E\.{'i'}){}$\5
+${}\{{}$\1\6
+${}\\{loc}\K\\{buffer}+\T{2};{}$\6
+\\{err\_print}(\.{"!!\ Missing\ @x\ in\ cha}\)\.{nge\ file"});\6
+\4${}\}{}$\2\6
+\4${}\}{}$\2\par
+\U12.\fi
+!vskip-.5!baselineskip
+\M{14}Here we are looking at lines following the \.{@x}.
+!vskip-.5!baselineskip
+\Y\B\4\X14:Skip to the next nonblank line; \PB{\&{return}} if end of file\X${}%
+\E{}$\6
+\&{do}\5
+${}\{{}$\1\6
+${}\\{change\_line}\PP;{}$\6
+\&{if} ${}(\R\\{input\_ln}(\\{change\_file})){}$\5
+${}\{{}$\1\6
+\\{err\_print}(\.{"!!\ Change\ file\ ended}\)\.{\ after\ @x"});\6
+\&{return};\6
+\4${}\}{}$\2\6
+\4${}\}{}$\2\5
+\&{while} ${}(\\{limit}\E\\{buffer}){}$;\par
+\U12.\fi
+!vskip-.5!baselineskip
+\M{15}\B\X15:Move \PB{\\{buffer}} and \PB{\\{limit}} to \PB{\\{change\_buffer}}
+and \PB{\\{change\_limit}}\X${}\E{}$\6
+${}\{{}$\1\6
+${}\\{change\_limit}\K\\{change\_buffer}-\\{buffer}+\\{limit};{}$\6
+${}\\{strncpy}(\\{change\_buffer},\39\\{buffer},\39\\{limit}-\\{buffer}+%
+\T{1});{}$\6
+\4${}\}{}$\2\par
+\Us12\ET16.\fi
+!endgroup
+\endgroup
+\vfil\eject
+
+\def\runninghead{APPENDIX A --- FINAL DOCUMENT}
+
+And here's what the same excerpt looks like when typeset.
+
+\M{12}Procedure \PB{\\{prime\_the\_change\_buffer}}
+sets \PB{\\{change\_buffer}} in preparation for the next matching operation.
+Since blank lines in the change file are not used for matching, we have
+\PB{$(\\{change\_limit}\E\\{change\_buffer}\W\R\\{changing})$} if and only if
+the change file is exhausted. This procedure is called only when
+\PB{\\{changing}} is 1; hence error messages will be reported correctly.
+
+\Y\B\&{void} \\{prime\_the\_change\_buffer}(\,)\1\1\2\2\6
+${}\{{}$\1\6
+${}\\{change\_limit}\K\\{change\_buffer}{}$;\C{ this value is used if the
+change file ends }\6
+\X13:Skip over comment lines in the change file; \PB{\&{return}} if end of file%
+\X;\6
+\X14:Skip to the next nonblank line; \PB{\&{return}} if end of file\X;\6
+\X15:Move \PB{\\{buffer}} and \PB{\\{limit}} to \PB{\\{change\_buffer}} and %
+\PB{\\{change\_limit}}\X;\6
+\4${}\}{}$\2\par
+\fi
+
+\M{13}While looking for a line that begins with \.{@x} in the change file, we
+allow lines that begin with \.{@}, as long as they don't begin with \.{@y},
+\.{@z}, or \.{@i} (which would probably mean that the change file is fouled up).
+
+\Y\B\4\X13:Skip over comment lines in the change file; \PB{\&{return}} if end
+of file\X${}\E{}$\6
+\&{while} (\T{1})\5
+${}\{{}$\1\6
+${}\\{change\_line}\PP;{}$\6
+\&{if} ${}(\R\\{input\_ln}(\\{change\_file})){}$\1\5
+\&{return};\2\6
+\&{if} ${}(\\{limit}<\\{buffer}+\T{2}){}$\1\5
+\&{continue};\2\6
+\&{if} ${}(\\{buffer}[\T{0}]\I\.{'@'}){}$\1\5
+\&{continue};\2\6
+\&{if} (\\{xisupper}(\\{buffer}[\T{1}]))\1\5
+${}\\{buffer}[\T{1}]\K\\{tolower}(\\{buffer}[\T{1}]);{}$\2\6
+\&{if} ${}(\\{buffer}[\T{1}]\E\.{'x'}){}$\1\5
+\&{break};\2\6
+\&{if} ${}(\\{buffer}[\T{1}]\E\.{'y'}\V\\{buffer}[\T{1}]\E\.{'z'}\V\\{buffer}[%
+\T{1}]\E\.{'i'}){}$\5
+${}\{{}$\1\6
+${}\\{loc}\K\\{buffer}+\T{2};{}$\6
+\\{err\_print}(\.{"!\ Missing\ @x\ in\ cha}\)\.{nge\ file"});\6
+\4${}\}{}$\2\6
+\4${}\}{}$\2\par
+\U12.\fi
+
+\M{14}Here we are looking at lines following the \.{@x}.
+
+\Y\B\4\X14:Skip to the next nonblank line; \PB{\&{return}} if end of file\X${}%
+\E{}$\6
+\&{do}\5
+${}\{{}$\1\6
+${}\\{change\_line}\PP;{}$\6
+\&{if} ${}(\R\\{input\_ln}(\\{change\_file})){}$\5
+${}\{{}$\1\6
+\\{err\_print}(\.{"!\ Change\ file\ ended}\)\.{\ after\ @x"});\6
+\&{return};\6
+\4${}\}{}$\2\6
+\4${}\}{}$\2\5
+\&{while} ${}(\\{limit}\E\\{buffer}){}$;\par
+\U12.\fi
+
+\M{15}\B\X15:Move \PB{\\{buffer}} and \PB{\\{limit}} to \PB{\\{change\_buffer}}
+and \PB{\\{change\_limit}}\X${}\E{}$\6
+${}\{{}$\1\6
+${}\\{change\_limit}\K\\{change\_buffer}-\\{buffer}+\\{limit};{}$\6
+${}\\{strncpy}(\\{change\_buffer},\39\\{buffer},\39\\{limit}-\\{buffer}+%
+\T{1});{}$\6
+\4${}\}{}$\2\par
+\Us12\ET16.\fi
+
+\vfil\eject\titletrue
+\rightskip=0pt % get out of C mode (cf. \B)
+\sfcode`;=1500 \pretolerance 200 \hyphenpenalty 50 \exhyphenpenalty 50
+
+\def\runninghead{APPENDIX B --- MACROS FOR FORMATTING}
+\section Appendix B: The \.{cwebmac.tex} file.
+This is the file that extends ``plain \TEX/'' format in order to support the
+features needed by the output of \.{CWEAVE}.
+
+\vskip6pt
+\begingroup \def\tt{\eighttt} \baselineskip9pt
+\def\printmacs{\begingroup
+  \def\do##1{\catcode`##1=12 } \dospecials
+  \parskip 0pt \parindent 0pt
+  \catcode`\ =13 \catcode`\^^M=13
+  \tt \verbatimdefs \input cwebmac \endgroup}
+\printmacs
+\endgroup
+\vfill\eject
+
+\def\runninghead{APPENDIX C --- NOTES ON FORMATTING}
+\section Appendix C: How to use \.{CWEB} macros.
+The macros in \.{cwebmac} make it possible to produce a variety of formats
+without editing the output of \.{CWEAVE}, and the purpose of this appendix
+is to explain some of the possibilities.
+
+\def\point#1.{\yskip\indent#1.\quad\ignorespaces}
+
+\point 1. Four fonts have been declared in addition to the standard fonts of
+\.{PLAIN} format: You can say `\.{\{\\mc UNIX\}}' to get {\mc UNIX} in
+medium-size caps; you can say `\.{\{\\sc STUFF\}}' to get {\sc STUFF}
+in small caps; and you can select the largish fonts \.{\\titlefont}
+and \.{\\ttitlefont} in the title of your document, where \.{\\ttitlefont}
+is a typewriter style of type. There are macros \.{\\UNIX/} and \.{\\CEE/}
+to refer to \UNIX/ and \CEE/ with medium-size caps.
+
+\point 2. When you mention an identifier in \TEX/ text, you normally call
+it `\.{|identifier|}'. But you can also say `\.{\\\\\{identifier\}}'. The
+output will look the same in both cases, but the second alternative
+doesn't put \\{identifier} into the index, since
+it bypasses \.{CWEAVE}'s translation from \CEE/ mode. In the second
+case you must put a backslash before each underline character
+in the identifier.
+
+\point 3. To get typewriter-like type, as when referring to `\.{CWEB}', you
+can use the `\.{\\.}' macro (e.g., `\.{\\.\{CWEB\}}'). In the argument to
+this macro you should insert an additional backslash before the symbols
+listed as `special string characters' in the index to \.{CWEAVE}, i.e.,
+before backslashes and dollar signs and the like.
+A `\.{\\\ }' here will result in the visible space symbol; to get an
+invisible space following a control sequence you can say `\.{\{\ \}}'.
+If the string is long, you can break it up into substrings that
+are separated by `\.{\\)}'\,; the latter gives a discretionary backslash
+if \TEX/ has to break a line here.
+
+\point 4. The three control sequences \.{\\pagewidth}, \.{\\pageheight},
+and \.{\\fullpageheight} can be redefined in the limbo section at the
+beginning of your \.{CWEB} file, to change the dimensions of each page.
+The default settings
+$$\lpile{\.{\\pagewidth=6.5in}\cr
+  \.{\\pageheight=8.7in}\cr
+  \.{\\fullpageheight=9in}\cr}$$
+were used to prepare this manual; \.{\\fullpageheight} is
+\.{\\pageheight} plus room for the additional heading and page numbers at
+the top of each page. If you change any of these quantities, you should
+call the macro \.{\\setpage} immediately after making the change.
+
+\point 5. The \.{\\pageshift} macro defines an amount by which right-hand
+pages (i.e., odd-numbered pages) are shifted right with respect to
+left-hand (even-numbered) ones. By adjusting this amount you may be
+able to get two-sided output in which the page numbers line up on
+opposite sides of each sheet.
+
+\point 6. The \.{\\title} macro will appear at the top of each page
+in small caps; it is the job name unless redefined.
+
+\point 7. The first page usually is assigned page
+number 1. To start on page 16, with contents
+on page 15, say this: `\.{\\def\\contentspagenumber\{15\}}
+\.{\\pageno=\\contentspagenumber} \.{\\advance\\pageno by 1}'.
+
+\point 8. The macro \.{\\iftitle} will suppress the header line if it is
+defined by `\.{\\titletrue}'. The normal value is \.{\\titlefalse}
+except for the table of contents; thus, the contents
+page is usually unnumbered.
+
+Two macros are provided to give flexibility to the table of
+contents: \.{\\topofcontents} is invoked just before the contents
+info is read, and \.{\\botofcontents} is invoked just after.
+Here's a typical definition:
+$$\lpile{\.{\\def\\topofcontents\{\\null\\vfill}\cr
+  \.{ { }\\titlefalse \% include headline on the contents page}\cr
+  \.{ { }\\def\\rheader\{\\mainfont The \{\\tt CWEAVE\}{ }processor\\hfil\}}\cr
+  \.{ { }\\centerline\{\\titlefont The \{\\ttitlefont CWEAVE\}{ }processor\}}\cr
+  \.{ { }\\vskip 15pt \\centerline\{(Version 3.64)\}{ }\\vfill\}}\cr}$$
+Redefining \.{\\rheader}, which is the headline for right-hand pages,
+suffices in this case to put the desired information at the top of the
+contents page.
+
+\point 9. Data for the table of contents is written to a file that
+is read after the indexes have been \TEX/ed; there's one line of data
+for every starred section. The file \.{common.toc} might look like this:
+$$\lpile{\.{\\ZZ \{Introduction\}\{0\}\{1\}\{28\}\{\}}\cr
+  \.{\\ZZ \{The character set\}\{2\}\{5\}\{29\}\{\}}\cr}$$
+and so on. The \.{\\topofcontents} macro could
+redefine \.{\\ZZ} so that the information appears in any desired format.
+(See also point~19 below.)
+
+\point 10. Sometimes it is necessary or desirable to divide the output of
+\.{CWEAVE} into subfiles that can be processed separately. For example,
+the listing of \TEX/ runs to more than 500 pages, and that is enough to
+exceed the capacity of many printing devices and/or their software.
+When an extremely large job isn't cut into smaller pieces, the entire
+process might be spoiled by a single error of some sort, making it
+necessary to start everything over.
+
+Here's a safe way to break a woven file into three parts:
+Say the pieces are $\alpha$,
+$\beta$, and $\gamma$, where each piece begins with a starred section.
+All macros should be defined in the opening limbo section of $\alpha$,
+and copies of this \TEX/ code should be placed at the
+beginning of $\beta$ and of $\gamma$. In order to process the parts
+separately, we need to take care of two things: The starting page
+numbers of $\beta$ and $\gamma$ need to be set up properly, and
+the table of contents data from all three runs needs to be
+accumulated.
+
+The \.{cwebmac} macros include two control sequences \.{\\contentsfile} and
+\.{\\readcontents} that facilitate the necessary processing.  We include
+`\.{\\def\\contentsfile\{cont1\}}' in the limbo section of $\alpha$, and
+we include `\.{\\def\\contentsfile\{cont2\}}' in the limbo section of
+$\beta$; this causes \TEX/ to write the contents data for $\alpha$ and $\beta$
+into \.{cont1.tex} and \.{cont2.tex}. Now in $\gamma$ we say
+$$\.{\\def\\readcontents\{\\input cont1 \\input cont2
+  \\input \\contentsfile\}}\,;$$
+this brings in the data from all three pieces, in the proper order.
+
+However, we still need to solve the page-numbering problem. One way to
+do it is to include the following in the limbo material for $\beta$:
+$$\lpile{\.{\\message\{Please type the last page number of part 1: \}}\cr
+  \.{\\read -1 to \\temp \\pageno=\\temp \\advance\\pageno by 1}\cr}$$
+Then you simply provide the necessary data when \TEX/ requests
+it; a similar construction is used at the beginning of $\gamma$.
+
+This method can, of course, be used to divide a woven file into
+any number of pieces.
+
+\point 11. Sometimes it is nice to include things in the index that are
+typeset in a special way. For example, we might want to have an
+index entry for `\TeX'. \.{CWEAVE} provides two simple ways to
+typeset an index entry (unless the entry is an identifier or a reserved word):
+`\.{@\^}' gives roman type, and `\.{@.}' gives typewriter type.
+But if we try to typeset `\TeX' in roman type by saying, e.g.,
+`\.{@\^\\TeX@>}', the backslash character gets in the way,
+and this entry wouldn't appear in the index with the T's.
+
+The solution is to use the `\.{@:}' feature, declaring a macro that
+simply removes a sort key as follows:
+$$\.{\\def\\9\#1\{\}}$$
+Now you can say, e.g., `\.{@:TeX\}\{\\TeX@>}' in your \.{CWEB} file; \.{CWEAVE}
+puts it into the index alphabetically, based on the sort key, and
+produces the macro call `\.{\\9\{TeX\}\{\\TeX\}}' which will ensure that
+the sort key isn't printed.
+
+A similar idea can be used to insert hidden material into section
+names so that they are alphabetized in whatever way you might wish.
+Some people call these tricks ``special refinements''; others call
+them ``kludges.''
+
+\point 12. The control sequence \.{\\secno} is set to the number of the
+section being typeset.
+
+\point 13. If you want to list only the sections that have changed,
+together with the index, put the command `\.{\\let\\maybe=\\iffalse}' in
+the limbo section before the first section of your \.{CWEB} file. It's
+customary to make this the first change in your change file.
+
+This feature has a \TeX nical limitation, however: You cannot use it
+together with control sequences like \.{\\proclaim} or \.{\\+} or
+\.{\\newcount} that plain \TeX\ has declared to be `\.{\\outer}',
+because \TeX\ refuses to skip silently over such control sequences.
+One way to work around this limitation is to say
+$$\.{\\fi \\let\\proclaim\\relax \\def\\proclaim\{...\} \\ifon}$$
+where \.{\\proclaim} is redefined to be the same as usual but without
+an \.{\\outer} qualification. (The \.{\\fi} here stops the conditional
+skipping, and the \.{\\ifon} turns it back on again.) Similarly,
+$$\.{\\fi \\newcount\\n \\ifon}$$
+is a safe way to use \.{\\newcount}. Plain \TeX\ already provides a
+non-outer macro \.{\\tabalign} that does the work of \.{\\+}; you can say
+$$\postdisplaypenalty=10000
+\.{\\fi \\let\\+\\tabalign \\ifon}$$
+if you prefer the shorter notation \.{\\+}.
+
+\point 14. To get output in languages other than English, redefine the
+macros \.{\\A}, \.{\\As}, \.{\\ATH},
+\.{\\ET}, \.{\\ETs}, \.{\\Q}, \.{\\Qs}, \.{\\U},
+\.{\\Us}, \.{\\ch}, \.{\\fin}, \.{\\con}, \.{\\today}, \.{\\datethis}, and
+\.{\\datecontentspage}. \.{CWEAVE} itself need not be changed.
+
+\point 15. Some output can be selectively suppressed with the macros
+\.{\\noatl}, \.{\\noinx}, \.{\\nosecs}, \.{\\nocon}.
+
+\point 16. All accents and special text symbols of plain \TEX/ format
+will work in \.{CWEB} documents just as they are described in
+Chapter~9 of {\sl The \TEX/book}, with one exception.
+The dot accent (normally \.{\\.}) must be typed \.{\\:} instead.
+
+\point 17. Several commented-out lines in \.{cwebmac.tex} are suggestions
+that users may wish to adopt. For example, one such line inserts a blank page
+if you have a duplex printer. Appendices D, E, and F of the complete
+version of this manual are printed using a commented-out option that
+substitutes `$\gets$' for `$=$' in the program listings. Looking at those
+appendices might help you decide which format you like better.
+
+\point 18. Andreas Scherer has contributed a macro called \.{\\pdfURL}
+with which one can say things like the following, anywhere in the \TeX\ parts
+or the \CEE/ comments of a \.{CWEB} file:
+$$\vbox{\halign{\.{#}\hfil\cr
+You can send email to
+ \\pdfURL\{the author\}\{mailto:andreas.scherer@@pobox.com\}\cr
+or visit \\pdfURL\{his home page\}\{http://www.pobox.com/%
+       \\TILDE/scherer\}.\cr}}$$
+In a {\mc PDF} document, the first argument will appear in blue as
+clickable text; the Acrobat reader, if correctly configured, will then
+redirect those links to the user's browser and open either the
+email client or the HTML viewer. In a hardcopy document, both arguments
+will be printed ({\tt the second in parentheses and typewriter type}).
+Certain special characters in an Internet address need to be handled
+in a somewhat awkward way, so that \.{CWEAVE} and/or \TeX\
+will not confuse them with formatting controls: Use \.{@@} for \.@
+and \.{\\TILDE/} for \.\~ and \.{\\UNDER/} for \.\_.
+
+\point 19. {\mc PDF} documents contain bookmarks that list all the major group
+titles in the table of contents, some of which will be subsidiary to
+others if the depth feature of \.{@*} has been used.
+Such bookmark entries are also known as ``outlines.''
+Moreover, the final group title, `Names of the sections',
+can be opened up to list every section name; Acrobat users can therefore
+navigate easily to any desired section.
+
+The macros of \.{cwebmac.tex} are careful to ``sanitize'' all the names
+that appear as bookmarks, by removing special characters and
+formatting codes that are inappropriate for the limited typographic
+capabilities of {\mc PDF} outlines. For example, one section of \.{CWEAVE}
+is named `Cases for \\{case\_like}', which is represented by the \TeX\ code
+`\.{Cases} \.{for} \.{\\PB\{\\\\\{case\\\_like\}\}}' in \.{cweave.tex}; its
+sanitized name is simply `\.{Cases} \.{for} \.{case\_like}'.
+(When \.{.pdf} files are produced, the fifth parameter of every \.{\\ZZ} in
+the \.{.toc} file is set to the sanitized form of the first parameter;
+see point~9 above and point~20 below.)
+
+In general, sanitization removes \TeX\ control sequences and braces,
+except for control sequences defined by \.{CWEB} itself. Such a translation
+works most of the time, but you can override the defaults and obtain any
+translation that you want by using \TeX nical tricks. For example, after
+$$\.{\\sanitizecommand\\foo\{bar\}}$$
+the control sequence \.{\\foo} will sanitize to `\.{bar}'. And after
+$$\.{\\def\\kluj\#1\\\\\{foo\}}$$
+the \TeX\ code `\.{\\kluj bar\\\\}' will print as `foo' but sanitize
+to `\.{bar}', because the control sequences \.{\\kluj} and
+\.{\\\\} are removed by sanitization.
+
+\point 20. Furthermore, group titles can be converted to an arbitrary
+sanitized text while also changing their form in running headlines, by
+using \.{\\ifheader}. Consider, for example, a \.{CWEB} source file that
+begins with the two lines
+$$\lpile{\.{\\def\\klujj\#1\\\\\{\\ifheader FOO\\else foo\\fi\}}\cr
+\.{@*Chinese \\klujj bar\\.}\cr}$$
+This coding introduces a major group entitled `{\bf Chinese foo}', with
+running headline `{\eightrm CHINESE FOO}' and table-of-contents entry
+`Chinese foo'. The corresponding bookmark is, however, `\.{Chinese} \.{bar}'.
+And the corresponding \.{.toc} file entry is
+`\.{\\ZZ \{Chinese \\klujj bar\\\\\}\{1\}\{1\}\{1\}\{Chinese bar\}}'.
+
+\vfill\end
+
-- 
cgit v1.2.3

