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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /language/xettex/waits-xe.ch
Initial commit
Diffstat (limited to 'language/xettex/waits-xe.ch')
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diff --git a/language/xettex/waits-xe.ch b/language/xettex/waits-xe.ch
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@@ -0,0 +1,1979 @@
+@x Tell WEAVE to print only the changes:
+ \def\?##1]{\hbox to 1in{\hfil##1.\ }}
+ }
+@y
+ \def\?##1]{\hbox{Changes to \hbox to 1em{\hfil##1}.\ }}
+ }
+\let\maybe=\iffalse
+@z
+
+@x WAITS's banner: [2]
+@d banner=='This is TeX, Version 2.0' {printed when \TeX\ starts}
+@y
+@d banner=='This is TeX-XeT, WAITS Version 2.0' {printed when \TeX\ starts}
+@z
+
+@x Switches for debugging and statistics: (7)
+@d debug==@{ {change this to `$\\{debug}\equiv\null$' when debugging}
+@d gubed==@t@>@} {change this to `$\\{gubed}\equiv\null$' when debugging}
+@f debug==begin
+@f gubed==end
+@#
+@d stat==@{ {change this to `$\\{stat}\equiv\null$' when gathering
+ usage statistics}
+@d tats==@t@>@} {change this to `$\\{tats}\equiv\null$' when gathering
+ usage statistics}
+@f stat==begin
+@f tats==end
+@y
+@d debug== {change this to `$\\{debug}\equiv\null$' when debugging}
+@d gubed== {change this to `$\\{gubed}\equiv\null$' when debugging}
+@f debug==begin
+@f gubed==end
+@#
+@d stat== {change this to `$\\{stat}\equiv\.{@@\{}$' when not
+ gathering usage statistics}
+@d tats== {change this to `$\\{tats}\equiv\.{@@\}}$' when not
+ gathering usage statistics}
+@f stat==begin
+@f tats==end
+@z
+
+@x The INITEX switch: (8)
+@d init== {change this to `$\\{init}\equiv\.{@@\{}$' in the production version}
+@d tini== {change this to `$\\{tini}\equiv\.{@@\}}$' in the production version}
+@y [In this case, no change is made]
+@d init== {change this to `$\\{init}\equiv\.{@@\{}$' in the production version}
+@d tini== {change this to `$\\{tini}\equiv\.{@@\}}$' in the production version}
+@z
+
+@x Compiler directives: (9)
+@{@&$C-,A+,D-@} {no range check, catch arithmetic overflow, no debug overhead}
+@!debug @{@&$C+,D+@}@+ gubed {but turn everything on when debugging}
+@y
+@{@&$C-,A+,D-,W+,H:0@}
+ {no range check, catch arithmetic overflow, no debug overhead, no heap}
+@!debug @{@&$C+,D:5,W+@}@+ gubed {but turn everything on when debugging}
+{the `|W+|' switch catches more syntax errors}
+{the `\ignorespaces|D:5|' avoids initial stop for the debugger}
+@z
+
+@x Compile-time constants: [11]
+@!mem_max=30000; {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=500; {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=72; {width of context lines on terminal error messages}
+@!half_error_line=42; {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=200; {maximum number of simultaneous input sources}
+@!max_in_open=6; {maximum number of input files and error insertions that
+ can be going on simultaneously}
+@!font_max=75; {maximum internal font number; must not exceed |max_quarterword|
+ and must be at most |font_base+256|}
+@!font_mem_size=20000; {number of words of |font_info| for all fonts}
+@!param_size=60; {maximum number of simultaneous macro parameters}
+@!nest_size=40; {maximum number of semantic levels simultaneously active}
+@!max_strings=3000; {maximum number of strings; must not exceed |max_halfword|}
+@!string_vacancies=8000; {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=32000; {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=600; {space for saving values outside of current group; must be
+ at most |max_halfword|}
+@!trie_size=8000; {space for hyphenation patterns; should be larger for
+ \.{INITEX} than it is in production versions of \TeX}
+@!dvi_buf_size=800; {size of the output buffer; must be a multiple of 8}
+@!file_name_size=40; {file names shouldn't be longer than this}
+@!pool_name='TeXformats:TEX.POOL ';
+ {string of length |file_name_size|; tells where the string pool appears}
+@.TeXformats@>
+@y
+@!mem_max=32000; {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=16000; {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=500; {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=80; {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=80; {width of longest text lines output; should be at least 60}
+@!stack_size=200; {maximum number of simultaneous input sources}
+@!max_in_open=6; {maximum number of input files and error insertions that
+ can be going on simultaneously}
+@!font_max=100;
+ {maximum internal font number; must not exceed |max_quarterword|}
+@!font_mem_size=23000; {number of words of |font_info| for all fonts}
+@!param_size=60; {maximum number of simultaneous macro parameters}
+@!nest_size=40; {maximum number of semantic levels simultaneously active}
+@!max_strings=3500; {maximum number of strings}
+@!string_vacancies=8000; {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=40000; {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 22500}
+@!save_size=300; {space for saving values outside of current group; must be
+ at most |max_halfword|}
+@!trie_size=8000; {space for hyphenation patterns; should be larger for
+ \.{INITEX} than it is in production versions of \TeX}
+@!dvi_buf_size=800; {size of the output buffer; must be a multiple of 8}
+@!file_name_size=23; {file names shouldn't be longer than this}
+@!pool_name='XET.POOL[XET,DEK] ';
+ {string of length |file_name_size|; tells where the string pool appears}
+@z
+
+@x TANGLE-time constants: (12)
+@d mem_bot=0 {smallest index in the |mem| array dumped by \.{INITEX};
+ must not be less than |mem_min|}
+@d mem_top==30000 {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=2100 {maximum number of control sequences; it should be at most
+ about |(mem_max-mem_min)/10|, but 2100 is already quite generous}
+@d hash_prime=1777 {a prime number equal to about 85\% of |hash_size|}
+@d hyph_size=307 {another prime; the number of \.{\\hyphenation} exceptions}
+@y
+@d mem_bot=16000 {smallest index in the |mem| array dumped by \.{INITEX};
+ must not be less than |mem_min|}
+@d mem_top==32000 {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=2500 {maximum number of control sequences; it should be at most
+ about |(mem_max-mem_min)/10|, but 2100 is already quite generous}
+@d hash_prime=2113 {a prime number equal to about 85\% of |hash_size|}
+@d hyph_size=307 {another prime; the number of \.{\\hyphenation} exceptions}
+@z
+
+@x System-dependent character set changes: (23)
+@^character set dependencies@>
+@^system dependencies@>
+
+@<Set init...@>=
+for i:=1 to @'37 do xchr[i]:=' ';
+@y
+@^character set dependencies@>
+@^system dependencies@>
+
+The code shown here is intended to be used on the Stanford {\sc SAIL} system,
+and at other installations like CMU and ISI where essentially the same
+extended character set is used. The fact that {\mc SAIL} has |'}'| in the
+wrong place turns out to cause no difficulty in this case.
+
+@<Set initial values...@>=
+for i:=1 to @'37 do xchr[i]:=chr(i);
+xchr[@'30]:=chr(@'137);
+xchr[@'32]:=chr(@'33); {|not_equal| sign}
+xchr[@'33]:=chr(@'176);
+@z
+
+@x Opening files: (27)
+@d reset_OK(#)==erstat(#)=0
+@d rewrite_OK(#)==erstat(#)=0
+
+@p function a_open_in(var f:alpha_file):boolean;
+ {open a text file for input}
+begin reset(f,name_of_file,'/O'); a_open_in:=reset_OK(f);
+end;
+@#
+function a_open_out(var f:alpha_file):boolean;
+ {open a text file for output}
+begin rewrite(f,name_of_file,'/O'); a_open_out:=rewrite_OK(f);
+end;
+@#
+function b_open_in(var f:byte_file):boolean;
+ {open a binary file for input}
+begin reset(f,name_of_file,'/O'); b_open_in:=reset_OK(f);
+end;
+@#
+function b_open_out(var f:byte_file):boolean;
+ {open a binary file for output}
+begin rewrite(f,name_of_file,'/O'); b_open_out:=rewrite_OK(f);
+end;
+@#
+function w_open_in(var f:word_file):boolean;
+ {open a word file for input}
+begin reset(f,name_of_file,'/O'); w_open_in:=reset_OK(f);
+end;
+@#
+function w_open_out(var f:word_file):boolean;
+ {open a word file for output}
+begin rewrite(f,name_of_file,'/O'); w_open_out:=rewrite_OK(f);
+end;
+@y
+@d reset_OK(#)==erstat(#) mod @'20000 = 0
+@d rewrite_OK(#)==erstat(#) mod @'20000 = 0
+
+@p function erstat(var f:file):integer; extern;@t/2@>
+@#
+function a_open_in(var f:alpha_file):boolean;
+ {open a text file for input}
+begin reset(f,name_of_file,'/E/O/N:9');
+ {the \.{/E} switch distinguishes |form_feed| from |carriage_return|;
+ the \.{/O} switch gives error control to us;
+ and the \.{/N:9} switch specifies 9 buffers, which
+ seems to work satisfactorily at {\mc SAIL}}
+a_open_in:=reset_OK(f);
+end;
+@#
+function a_open_out(var f:alpha_file):boolean;
+ {open a text file for output}
+begin rewrite(f,name_of_file,'/O/N:2'); a_open_out:=rewrite_OK(f);
+end; {two buffers seems adequate for text output files}
+@#
+function b_open_in(var f:byte_file):boolean;
+ {open a binary file for input}
+begin reset(f,name_of_file,'/B:8/O/N:2'); b_open_in:=reset_OK(f);
+end; {the \.{/B} switch is necessary to get byte packing}
+@#
+function b_open_out(var f:byte_file):boolean;
+ {open a binary file for output}
+begin rewrite(f,name_of_file,'/O/N:9/P:256'); b_open_out:=rewrite_OK(f);
+end; {here we use |ary_out| so the \.{/B} switch isn't appropriate}
+ {the \.{/P:256} sets file protection to `dump never'}
+@#
+function w_open_in(var f:word_file):boolean;
+ {open a word file for input}
+begin reset(f,name_of_file,'/O/N:9'); w_open_in:=reset_OK(f);
+end;
+@#
+function w_open_out(var f:word_file):boolean;
+ {open a word file for output}
+begin rewrite(f,name_of_file,'/O/N:9'); w_open_out:=rewrite_OK(f);
+end;
+@z
+
+@x New input_ln: (31)
+@ 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...@>=
+@!buffer:array[0..buf_size] of ASCII_code; {lines of characters being read}
+@!first:0..buf_size; {the first unused position in |buffer|}
+@!last:0..buf_size; {end of the line just input to |buffer|}
+@!max_buf_stack:0..buf_size; {largest index used in |buffer|}
+@y
+@ 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.
+
+We will read the lines first into an auxiliary buffer, in order to
+save the running time of procedure-call overhead. This uses a nice
+feature of \ph\ that Knuth chose not to mention in \TeX82.
+@^Knuth, Donald Ervin@>
+
+At {\mc SAIL} we want to recognize page marks (indicated by |form_feed|
+characters), and keep track of the current page number.
+
+@d form_feed=@'14 {ASCII code used at end of a page}
+
+@<Glob...@>=
+@!buffer:array[0..buf_size] of ASCII_code; {lines of characters being read}
+@!first:0..buf_size; {the first unused position in |buffer|}
+@!last:0..buf_size; {end of the line just input to |buffer|}
+@!max_buf_stack:0..buf_size; {largest index used in |buffer|}
+@!aux_buf:array[0..70] of text_char; {where the characters go first}
+@^system dependencies@>
+@z
+@x
+@p function input_ln(var f:alpha_file;@!bypass_eoln:boolean):boolean;
+ {inputs the next line or returns |false|}
+var last_nonblank:0..buf_size; {|last| with trailing blanks removed}
+begin if bypass_eoln then if not eof(f) then get(f);
+ {input the first character of the line into |f^|}
+last:=first; {cf.\ Matthew 19\thinspace:\thinspace30}
+if eof(f) then input_ln:=false
+else begin last_nonblank:=first;
+ while not eoln(f) do
+ begin if last>=max_buf_stack then
+ begin max_buf_stack:=last+1;
+ if max_buf_stack=buf_size then
+ overflow("buffer size",buf_size);
+@:TeX capacity exceeded buffer size}{\quad buffer size@>
+ end;
+ buffer[last]:=xord[f^]; get(f); incr(last);
+ if buffer[last-1]<>" " then last_nonblank:=last;
+ end;
+ last:=last_nonblank; input_ln:=true;
+ end;
+end;
+@y
+@p function input_ln(var f:alpha_file;@!bypass_eoln:boolean):boolean;
+ {inputs the next line or returns |false|}
+label 1,done;
+var n: integer;
+@!k,@!m: 0..buf_size; {indices into |buffer|}
+begin if bypass_eoln then {input the first character of the line into |f^|}
+ begin if not eof(f) then get(f);
+ if not eof(f) then if f^=chr(@'12) then get(f); {skip past a |line_feed|}
+ end;
+last:=first;
+if eof(f) then input_ln:=false
+else begin read(f,aux_buf:n);
+ if buffer[first]=form_feed then {previous line was end-of-page}
+ begin incr(page); line:=1; {adjust line and page numbers}
+ end;
+1: if last+n>max_buf_stack then
+ if last+n>=buf_size then
+ begin max_buf_stack:=buf_size;
+ overflow("buffer size",buf_size);
+@:TeX capacity exceeded buffer size}{\quad buffer size@>
+ end
+ else max_buf_stack:=last+n;
+ if n>0 then
+ begin m:=last;
+ if n=72 then last:=m+71@+else last:=m+n;
+ for k:=m to last-1 do buffer[k]:=xord[aux_buf[k-m]];
+ if n=72 then {there's more on this line}
+ begin read(f,aux_buf:n); goto 1;
+ end;
+ end
+ else if f^=chr(form_feed) then {end of page}
+ begin aux_buf[0]:=f^; n:=1; goto 1;
+ end;
+ loop@+ begin if last=first then goto done;
+ if buffer[last-1]<>" " then goto done;
+ decr(last);
+ end;
+done: input_ln:=true;
+ end;
+end;
+@^system dependencies@>
+@z
+
+@x Terminal I/O: (32)
+is considered an output file the file variable is |term_out|.
+@^system dependencies@>
+
+@<Glob...@>=
+@!term_in:alpha_file; {the terminal as an input file}
+@!term_out:alpha_file; {the terminal as an output file}
+
+@ Here is how to open the terminal files
+in \ph. The `\.{/I}' switch suppresses the first |get|.
+@^system dependencies@>
+
+@d t_open_in==reset(term_in,'TTY:','/O/I') {open the terminal for text input}
+@d t_open_out==rewrite(term_out,'TTY:','/O') {open the terminal for text output}
+@y
+is considered an output file the file variable is |term_out|.
+On WAITS, this point is moot, since we use the built-in |TTY| file.
+@^system dependencies@>
+
+@d term_in==TTY {the terminal as an input file}
+@d term_out==TTY {the terminal as an output file}
+
+@ Here is how to open the terminal files on WAITS: we don't do anything,
+since |TTY| is always open. Note that |eoln(term_in)| is initially |true|.
+@^system dependencies@>
+
+@d t_open_in==do_nothing {open the terminal for text input}
+@d t_open_out==do_nothing {open the terminal for text output}
+@z
+
+@x Special terminal controls: (34)
+@d clear_terminal == break_in(term_in,true) {clear the terminal input buffer}
+@d wake_up_terminal == do_nothing {cancel the user's cancellation of output}
+@y
+@d clear_terminal == break_in(term_in,true) {clear the terminal input buffer}
+@d wake_up_terminal == begin if inskp0 then end
+ {cancel the user's cancellation of output}
+
+@<Error handling procedures@>=
+function inskp0:boolean; extern;
+@z
+
+@x Initializing the terminal: (37)
+@ The following program does the required initialization
+without retrieving a possible command line.
+It should be clear how to modify this routine to deal with command lines,
+if the system permits them.
+@^system dependencies@>
+
+@p function init_terminal:boolean; {gets the terminal input started}
+label exit;
+begin t_open_in;
+loop@+begin wake_up_terminal; write(term_out,'**'); update_terminal;
+@.**@>
+ if not input_ln(term_in,true) then {this shouldn't happen}
+ begin write_ln(term_out);
+ write(term_out,'! End of file on the terminal... why?');
+@.End of file on the terminal@>
+ init_terminal:=false; return;
+ end;
+ loc:=first;
+ while (loc<last)and(buffer[loc]=" ") do incr(loc);
+ if loc<last then
+ begin init_terminal:=true;
+ return; {return unless the line was all blank}
+ end;
+ write_ln(term_out,'Please type the name of your input file.');
+ end;
+exit:end;
+@y
+@ The following program does the required initialization
+and accepts interrupts and also retrieves a possible command line, using
+new system routines due to David R. Fuchs.
+@^Fuchs, David Raymond@>
+
+@d pto_chr(#)==ptwr1w(0,ord(#)) {put a character in the line editor}
+
+@p procedure esci(var x:integer); extern; @t\2@>@;
+ {increments |x| each time the user types escape-I or break-I;
+ the program can change |x| whenever it wants to, but |x| had
+ better be a global variable}
+@#
+function rescan:boolean; extern; @t\2@>@;
+ {puts the command line into the terminal buffer,
+ or returns |false| if there was no command line}
+@#
+function tmp_in(f:string;var s:string):integer; extern;
+ @t\2@>@;
+ {reads \.{TMPCOR} file |f| into |s|, and returns its length
+ (|<=0| means error)}
+@#
+function cclsw: boolean; extern; @t\2@>@;
+ {was program started with \.{RUN} offset of 1 (i.e., from \.{SNAIL})?}
+@#
+procedure ptwr1w(pty,c:integer); extern; @t\2@>@;
+ {simulates typing of a character on a \.{PTY}}
+@#
+function init_terminal:boolean; {gets the terminal files started}
+label exit;
+var l:integer; {length returned by |tmp_in|}
+@!line_found:boolean; {have we scanned a line?}
+@!tmp_cor_buf:packed array[0..100] of char; {where |tmp_in| puts things}
+begin t_open_in;
+esci(interrupt);
+last:=first;
+if cclsw then {started by \.{TEX} monitor command}
+ begin l:=tmp_in('TEX',tmp_cor_buf);
+ loc:=1;
+ while (loc<l)and(tmp_cor_buf[loc]<>':=') do incr(loc);
+ incr(loc);
+ while loc<l do
+ begin if tmp_cor_buf[loc]>' ' then
+ begin buffer[last]:=xord[tmp_cor_buf[loc]]; incr(last);
+ end;
+ incr(loc);
+ end;
+ end
+else
+@!debug if false then@;@+gubed@;@/
+if rescan then
+ begin read_ln(term_in); {get first character into |term_in^|}
+ while (not eoln(term_in))and(term_in^<>';') do get(term_in);
+ if term_in^=';' then
+ begin get(term_in);
+ while not eoln(term_in) do
+ begin buffer[last]:=xord[term_in^]; incr(last); get(term_in);
+ end;
+ end;
+ end;
+line_found:=(last>first);
+loop@+ begin loc:=first;
+ while (loc<last)and(buffer[loc]=" ") do incr(loc);
+ if loc<last then
+ begin init_terminal:=true;
+ return; {return unless the line was all blank}
+ end;
+ if line_found then
+ write_ln(term_out,'Please type the name of your input file.');
+ wake_up_terminal; write(term_out,'**'); update_terminal;
+@.**@>
+ buffer[first]:=0; {|input_ln| may look at |buffer[first]|}
+ if not input_ln(term_in,true) then {this shouldn't happen}
+ begin write_ln(term_out);
+ write(term_out,'! End of file on the terminal... why?');
+@.End of file on the terminal@>
+ init_terminal:=false; return;
+ end;
+ line_found:=true;
+ end;
+exit:end;
+@^system dependencies@>
+@z
+
+@x Making special characters printable: (49)
+@<Character |k| cannot be printed@>=
+ (k<" ")or(k>"~")
+@y
+@<Character |k| cannot be printed@>=
+ (k=@'177)or(k in [0,@'11..@'15,@'33])
+@z
+
+@x Terminal input: (71)
+begin update_terminal; {Now the user sees the prompt for sure}
+@y
+begin update_terminal; {Now the user sees the prompt for sure}
+buffer[first]:=0; {makes sure |input_ln| doesn't find a |form_feed|}
+@z
+
+@x The `E' option: (84)
+line ready to be edited. But such an extension requires some system
+wizardry, so the present implementation simply types out what file should be
+edited and the relevant line number.
+@y
+line ready to be edited. The present implementation does this by loading
+the line editor with the appropriate call to the editor. We treat `\.T' the
+same as `\.E', because other programs on this system invoke the editor
+when the user says `\.T'.
+@z
+@x
+"E": if base_ptr>0 then
+ begin print_nl("You want to edit file ");
+@.You want to edit file x@>
+ print(input_stack[base_ptr].name_field);
+ print(" at line "); print_int(line);
+ interaction:=scroll_mode; jump_out;
+ end;
+@y
+"E","T": if base_ptr>0 then
+ begin selector:=new_string; pool_ptr:=str_start[str_ptr];
+ print("et "); print(input_stack[base_ptr].name_field);
+ print_char("/"); print_int(page); print("p/");
+ print_int(line); print_char("l"); print_char(carriage_return);
+ if str_ptr<max_strings then
+ begin pseudo_typein:=str_ptr; incr(str_ptr);
+ str_start[str_ptr]:=pool_ptr;
+ end; {|make_string| not declared |forward|}
+ selector:=term_and_log; interaction:=scroll_mode; jump_out;
+ end;
+@z
+
+@x Changes for 36-bit machines: (110)
+The values defined here are recommended for most 32-bit computers.
+
+@d min_quarterword=0 {smallest allowable value in a |quarterword|}
+@d max_quarterword=255 {largest allowable value in a |quarterword|}
+@d min_halfword==0 {smallest allowable value in a |halfword|}
+@d max_halfword==65535 {largest allowable value in a |halfword|}
+@y
+The values defined here are recommended for most 36-bit computers.
+
+@d min_quarterword=0 {smallest allowable value in a |quarterword|}
+@d max_quarterword=511 {largest allowable value in a |quarterword|}
+@d min_halfword==0 {smallest allowable value in a |halfword|}
+@d max_halfword==262143 {largest allowable value in a |halfword|}
+@z
+
+@x Eliminating addition/subtraction of zero: (112)
+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(#)==#+min_quarterword
+ {to put an |eight_bits| item into a quarterword}
+@d qo(#)==#-min_quarterword
+ {to take an |eight_bits| item out of a quarterword}
+@d hi(#)==#+min_halfword
+ {to put a sixteen-bit item into a halfword}
+@d ho(#)==#-min_halfword
+ {to take a sixteen-bit item from a halfword}
+@y
+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|.
+So they have been simplified here in the obvious way.
+@^inner loop@>@^system dependencies@>
+
+@d qi(#)==# {to put an |eight_bits| item into a quarterword}
+@d qo(#)==# {to take an |eight_bits| item from a quarterword}
+@d hi(#)==# {to put a sixteen-bit item into a halfword}
+@d ho(#)==# {to take a sixteen-bit item from a halfword}
+@z
+
+@x Kludge to get around Pascal bug (with large array lower bounds) (116)
+@!mem : array[mem_min..mem_max] of memory_word; {the big dynamic storage area}
+@y
+@z
+
+@x make room for a new creation procedure [161]
+\TeX's other algorithms intact.
+@^system dependencies@>
+@y
+\TeX's other algorithms intact.
+@^system dependencies@>
+@p@<Declare functions needed for special kinds of nodes@>
+@z
+
+@x New command code [208-209]
+@d max_non_prefixed_command=69 {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=70 {token list register ( \.{\\toks} )}
+@d assign_toks=71 {special token list ( \.{\\output}, \.{\\everypar}, etc.~)}
+@d assign_int=72 {user-defined integer ( \.{\\tolerance}, \.{\\day}, etc.~)}
+@d assign_dimen=73 {user-defined length ( \.{\\hsize}, etc.~)}
+@d assign_glue=74 {user-defined glue ( \.{\\baselineskip}, etc.~)}
+@d assign_mu_glue=75 {user-defined muglue ( \.{\\thinmuskip}, etc.~)}
+@d assign_font_dimen=76 {user-defined font dimension ( \.{\\fontdimen} )}
+@d assign_font_int=77 {user-defined font integer ( \.{\\hyphenchar},
+ \.{\\skewchar} )}
+@d set_aux=78 {specify state info ( \.{\\spacefactor}, \.{\\prevdepth} )}
+@d set_prev_graf=79 {specify state info ( \.{\\prevgraf} )}
+@d set_page_dimen=80 {specify state info ( \.{\\pagegoal}, etc.~)}
+@d set_page_int=81 {specify state info ( \.{\\deadcycles},
+ \.{\\insertpenalties} )}
+@d set_box_dimen=82 {change dimension of box ( \.{\\wd}, \.{\\ht}, \.{\\dp} )}
+@d set_shape=83 {specify fancy paragraph shape ( \.{\\parshape} )}
+@d def_code=84 {define a character code ( \.{\\catcode}, etc.~)}
+@d def_family=85 {declare math fonts ( \.{\\textfont}, etc.~)}
+@d set_font=86 {set current font ( font identifiers )}
+@d def_font=87 {define a font file ( \.{\\font} )}
+@d register=88 {internal register ( \.{\\count}, \.{\\dimen}, etc.~)}
+@d max_internal=88 {the largest code that can follow \.{\\the}}
+@d advance=89 {advance a register or parameter ( \.{\\advance} )}
+@d multiply=90 {multiply a register or parameter ( \.{\\multiply} )}
+@d divide=91 {divide a register or parameter ( \.{\\divide} )}
+@d prefix=92 {qualify a definition ( \.{\\global}, \.{\\long}, \.{\\outer} )}
+@d let=93 {assign a command code ( \.{\\let}, \.{\\futurelet} )}
+@d shorthand_def=94 {code definition ( \.{\\chardef}, \.{\\countdef}, etc.~)}
+@d read_to_cs=95 {read into a control sequence ( \.{\\read} )}
+@d def=96 {macro definition ( \.{\\def}, \.{\\gdef}, \.{\\xdef}, \.{\\edef} )}
+@d set_box=97 {set a box ( \.{\\setbox} )}
+@d hyph_data=98 {hyphenation data ( \.{\\hyphenation}, \.{\\patterns} )}
+@d set_interaction=99 {define level of interaction ( \.{\\batchmode}, etc.~)}
+@d max_command=99 {the largest command code seen at |big_switch|}
+@y
+@d LR=70 {text direction ( \.{\\beginL}, \.{\\beginR}, \.{\\endL}, \.{\\endR} )}
+@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} )}
+@d set_box_dimen=83 {change dimension of box ( \.{\\wd}, \.{\\ht}, \.{\\dp} )}
+@d set_shape=84 {specify fancy paragraph shape ( \.{\\parshape} )}
+@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 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} )}
+@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} )}
+@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|}
+@z
+
+@x Special form_feed initialization: (232)
+cat_code("\"):=escape; cat_code("%"):=comment;
+@y
+cat_code("\"):=escape; cat_code("%"):=comment;
+cat_code(form_feed):=car_ret;
+@z
+
+@x Date and time: (241)
+Since standard \PASCAL\ cannot provide such information, something special
+is needed. The program here simply specifies July 4, 1776, at noon; but
+users probably want a better approximation to the truth.
+
+@p procedure fix_date_and_time;
+begin time:=12*60; {minutes since midnight}
+day:=4; {fourth day of the month}
+month:=7; {seventh month of the year}
+year:=1776; {Anno Domini}
+end;
+@y
+It uses a {\mc WAITS} monitor call that puts the date in the left 18 bits
+and the time in the right 18 bits.
+
+@p procedure fix_date_and_time;
+var t:integer; {accumulator}
+date:integer; {raw date}
+g:boolean; {garbage}
+begin call_i(@'400101,,t,t,g); {that's \.{ACCTIM}}
+date:=t div @'1000000;
+time:=(t mod @'1000000) div 60;
+day:=(date mod 31)+1;
+month:=((date div 31) mod 12)+1;
+year:=(date div (31*12))+1964;
+end;
+@z
+
+@x Page number maintenance: (304)
+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..max_in_open] of integer|\unskip'
+by analogy with |line_stack|.
+@y
+Similarly, we maintain a global variable |page| and a corresponding
+|page_stack|.
+@z
+@x
+@!line_stack : array[1..max_in_open] of integer;
+@y
+@!line_stack : array[1..max_in_open] of integer;
+@!page : integer; {current page number in the current source file}
+@!page_stack : array[1..max_in_open] of integer;
+@z
+
+@x Printing the page number: (313)
+else begin print_nl("l."); print_int(line);
+@y
+else begin if page>1 then
+ begin print_nl("p."); print_int(page); print(",l.");
+ end
+ else print_nl("l.");
+ print_int(line);
+@z
+
+@x More page number maintenance: (328)
+or |limit| or |line|.
+@y
+or |limit| or |line| or |page|.
+@z
+@x
+line_stack[index]:=line; start:=first; state:=mid_line;
+@y
+line_stack[index]:=line; start:=first; state:=mid_line;
+page_stack[index]:=page;
+@z
+@x
+begin first:=start; line:=line_stack[index];
+@y
+begin first:=start; page:=page_stack[index]; line:=line_stack[index];
+@z
+
+@x More page number printing: (336)
+ print("; all text was ignored after line "); print_int(skip_line);
+@y
+ print("; all text was ignored after line "); print_int(skip_line);
+ if skip_page>1 then
+ begin print(", p."); print_int(skip_page);
+ end;
+@z
+
+@x Pausing on input: (363)
+@ 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 procedure firm_up_the_line;
+var k:0..buf_size; {an index into |buffer|}
+begin limit:=last;
+if pausing>0 then if interaction>nonstop_mode then
+ begin wake_up_terminal; print_ln;
+ if start<limit then for k:=start to limit-1 do print(buffer[k]);
+ first:=limit; prompt_input("=>"); {wait for user response}
+@.=>@>
+ if last>first then
+ begin for k:=first to last-1 do {move line down in buffer}
+ buffer[k+start-first]:=buffer[k];
+ limit:=start+last-first;
+ end;
+ end;
+end;
+@y
+@ If the user}
+@d wake_up_terminal == do_nothing {cancel the user's cancellation of output}
+@y
+@d clear_terminal == break_in(term_in,true) {clear the terminal input buffer}
+@d wake_up_terminal == begin if inskp0 then end
+ {cancel the user's cancellation of output}
+
+@<Error handling procedures@>=
+function inskp0:boolean; extern;
+@z
+
+@x Initializing the terminal: (37)
+@ The following program does the required initialization
+without retrieving a possible command line.
+It should be clear how to modify this routine to deal with command lines,
+if the system permits them.
+@^system dependencies@>
+
+@p function init_terminal:boolean; {gets the terminal input started}
+label exit;
+begin t_open_in;
+loop@+begin wake_up_terminal; write(term_out,'**'); update_terminal;
+@.**@>
+ if not input_ln(term_in,true) then {this shouldn't happen}
+ begin write_ln(term_out);
+ write(term_out,'! End of file on the terminal... why?');
+@.End of file on the terminal@>
+ init_terminal:=false; return;
+ end;
+ loc:=first;
+ while (loc<last)and(buffer[loc]=" ") do incr(loc);
+ if loc<last then
+ begin init_terminal:=true;
+ return; {return unless the line was all blank}
+ end;
+ write_ln(term_out,'Please type the name of your input file.');
+ end;
+exit:end;
+@y
+@ The following program does the required initialization
+and accepts interrupts and also retrieves a possible command line, using
+new system routines due to David R. Fuchs.
+@^Fuchs, David Raymond@>
+
+@d pto_chr(#)==ptwr1w(0,ord(#)) {put a character in the line editor}
+
+@p procedure esci(var x:integer); extern; @t\2@>@;
+ {increments |x| each time the user types escape-I or break-I;
+ the program can change |x| whenever it wants to, but |x| had
+ better be a global variable}
+@#
+function rescan:boolean; extern; @t\2@>@;
+ {puts the command line into the terminal buffer,
+ or returns |false| if there was no command line}
+@#
+function tmp_in(f:string;var s:string):integer; extern;
+ @t\2@>@;
+ {reads \.{TMPCOR} file |f| into |s|, and returns its length
+ (|<=0| means error)}
+@#
+function cclsw: boolean; extern; @t\2@>@;
+ {was program started with \.{RUN} offset of 1 (i.e., from \.{SNAIL})?}
+@#
+procedure ptwr1w(pty,c:integer); extern; @t\2@>@;
+ {simulates typing of a character on a \.{PTY}}
+@#
+function init_terminal:boolean; {gets the terminal files started}
+label exit;
+var l:integer; {length returned by |tmp_in|}
+@!line_found:boolean; {have we scanned a line?}
+@!tmp_cor_buf:packed array[0..100] of char; {where |tmp_in| puts things}
+begin t_open_in;
+esci(interrupt);
+last:=first;
+if cclsw then {started by \.{TEX} monitor command}
+ begin l:=tmp_in('TEX',tmp_cor_buf);
+ loc:=1;
+ while (loc<l)and(tmp_cor_buf[loc]<>':=') do incr(loc);
+ incr(loc);
+ while loc<l do
+ begin if tmp_cor_buf[loc]>' ' then
+ begin buffer[last]:=xord[tmp_cor_buf[loc]]; incr(last);
+ end;
+ incr(loc);
+ end;
+ end
+else
+@!debug if false then@;@+gubed@;@/
+if rescan then
+ begin read_ln(term_in); {get first character into |term_in^|}
+ while (not eoln(term_in))and(term_in^<>';') do get(term_in);
+ if term_in^=';' then
+ begin get(term_in);
+ while not eoln(term_in) do
+ begin buffer[last]:=xord[term_in^]; incr(last); get(term_in);
+ end;
+ end;
+ end;
+line_found:=(last>first);
+loop@+ begin loc:=first;
+ while (loc<last)and(buffer[loc]=" ") do incr(loc);
+ if loc<last then
+ begin init_terminal:=true;
+ return; {return unless the line was all blank}
+ end;
+ if line_found then
+ write_ln(term_out,'Please type the name of your input file.');
+ wake_up_terminal; write(term_out,'**'); update_terminal;
+@.**@>
+ buffer[first]:=0; {|input_ln| may look at |buffer[first]|}
+ if not input_ln(term_in,true) then {this shouldn't happen}
+ begin write_ln(term_out);
+ write(term_out,'! End of file on the terminal... why?');
+@.End of file on the terminal@>
+ init_terminal:=false; return;
+ end;
+ line_found:=true;
+ end;
+exit:end;
+@^system dependencies@>
+@z
+
+@x Making special characters printable: (49)
+@<Character |k| cannot be printed@>=
+ (k<" ")or(k>"~")
+@y
+@<Character |k| cannot be printed@>=
+ (k=@'177)or(k in [0,@'11..@'15,@'33])
+@z
+
+@x Terminal input: (71)
+begin update_terminal; {Now the user sees the prompt for sure}
+@y
+begin update_terminal; {Now the user sees the prompt for sure}
+buffer[first]:=0; {makes sure |input_ln| doesn't find a |form_feed|}
+@z
+
+@x The `E' option: (84)
+line ready to be edited. But such an extension requires some system
+wizardry, so the present implementation simply types out what file should be
+edited and the relevant line number.
+@y
+line ready to be edited. The present implementation does this by loading
+the line editor with the appropriate call to the editor. We treat `\.T' the
+same as `\.E', because other programs on this system invoke the editor
+when the user says `\.T'.
+@z
+@x
+"E": if base_ptr>0 then
+ begin print_nl("You want to edit file ");
+@.You want to edit file x@>
+ print(input_stack[base_ptr].name_field);
+ print(" at line "); print_int(line);
+ interaction:=scroll_mode; jump_out;
+ end;
+@y
+"E","T": if base_ptr>0 then
+ begin selector:=new_string; pool_ptr:=str_start[str_ptr];
+ print("et "); print(input_stack[base_ptr].name_field);
+ print_char("/"); print_int(page); print("p/");
+ print_int(line); print_char("l"); print_char(carriage_return);
+ if str_ptr<max_strings then
+ begin pseudo_typein:=str_ptr; incr(str_ptr);
+ str_start[str_ptr]:=pool_ptr;
+ end; {|make_string| not declared |forward|}
+ selector:=term_and_log; interaction:=scroll_mode; jump_out;
+ end;
+@z
+
+@x Changes for 36-bit machines: (110)
+The values defined here are recommended for most 32-bit computers.
+
+@d min_quarterword=0 {smallest allowable value in a |quarterword|}
+@d max_quarterword=255 {largest allowable value in a |quarterword|}
+@d min_halfword==0 {smallest allowable value in a |halfword|}
+@d max_halfword==65535 {largest allowable value in a |halfword|}
+@y
+The values defined here are recommended for most 36-bit computers.
+
+@d min_quarterword=0 {smallest allowable value in a |quarterword|}
+@d max_quarterword=511 {largest allowable value in a |quarterword|}
+@d min_halfword==0 {smallest allowable value in a |halfword|}
+@d max_halfword==262143 {largest allowable value in a |halfword|}
+@z
+
+@x Eliminating addition/subtraction of zero: (112)
+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(#)==#+min_quarterword
+ {to put an |eight_bits| item into a quarterword}
+@d qo(#)==#-min_quarterword
+ {to take an |eight_bits| item out of a quarterword}
+@d hi(#)==#+min_halfword
+ {to put a sixteen-bit item into a halfword}
+@d ho(#)==#-min_halfword
+ {to take a sixteen-bit item from a halfword}
+@y
+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|.
+So they have been simplified here in the obvious way.
+@^inner loop@>@^system dependencies@>
+
+@d qi(#)==# {to put an |eight_bits| item into a quarterword}
+@d qo(#)==# {to take an |eight_bits| item from a quarterword}
+@d hi(#)==# {to put a sixteen-bit item into a halfword}
+@d ho(#)==# {to take a sixteen-bit item from a halfword}
+@z
+
+@x Kludge to get around Pascal bug (with large array lower bounds) (116)
+@!mem : array[mem_min..mem_max] of memory_word; {the big dynamic storage area}
+@y
+@z
+
+@x make room for a new creation procedure [161]
+\TeX's other algorithms intact.
+@^system dependencies@>
+@y
+\TeX's other algorithms intact.
+@^system dependencies@>
+@p@<Declare functions needed for special kinds of nodes@>
+@z
+
+@x New command code [208-209]
+@d max_non_prefixed_command=69 {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=70 {token list register ( \.{\\toks} )}
+@d assign_toks=71 {special token list ( \.{\\output}, \.{\\everypar}, etc.~)}
+@d assign_int=72 {user-defined integer ( \.{\\tolerance}, \.{\\day}, etc.~)}
+@d assign_dimen=73 {user-defined length ( \.{\\hsize}, etc.~)}
+@d assign_glue=74 {user-defined glue ( \.{\\baselineskip}, etc.~)}
+@d assign_mu_glue=75 {user-defined muglue ( \.{\\thinmuskip}, etc.~)}
+@d assign_font_dimen=76 {user-defined font dimension ( \.{\\fontdimen} )}
+@d assign_font_int=77 {user-defined font integer ( \.{\\hyphenchar},
+ \.{\\skewchar} )}
+@d set_aux=78 {specify state info ( \.{\\spacefactor}, \.{\\prevdepth} )}
+@d set_prev_graf=79 {specify state info ( \.{\\prevgraf} )}
+@d set_page_dimen=80 {specify state info ( \.{\\pagegoal}, etc.~)}
+@d set_page_int=81 {specify state info ( \.{\\deadcycles},
+ \.{\\insertpenalties} )}
+@d set_box_dimen=82 {change dimension of box ( \.{\\wd}, \.{\\ht}, \.{\\dp} )}
+@d set_shape=83 {specify fancy paragraph shape ( \.{\\parshape} )}
+@d def_code=84 {define a character code ( \.{\\catcode}, etc.~)}
+@d def_family=85 {declare math fonts ( \.{\\textfont}, etc.~)}
+@d set_font=86 {set current font ( font identifiers )}
+@d def_font=87 {define a font file ( \.{\\font} )}
+@d register=88 {internal register ( \.{\\count}, \.{\\dimen}, etc.~)}
+@d max_internal=88 {the largest code that can follow \.{\\the}}
+@d advance=89 {advance a register or parameter ( \.{\\advance} )}
+@d multiply=90 {multiply a register or parameter ( \.{\\multiply} )}
+@d divide=91 {divide a register or parameter ( \.{\\divide} )}
+@d prefix=92 {qualify a definition ( \.{\\global}, \.{\\long}, \.{\\outer} )}
+@d let=93 {assign a command code ( \.{\\let}, \.{\\futurelet} )}
+@d shorthand_def=94 {code definition ( \.{\\chardef}, \.{\\countdef}, etc.~)}
+@d read_to_cs=95 {read into a control sequence ( \.{\\read} )}
+@d def=96 {macro definition ( \.{\\def}, \.{\\gdef}, \.{\\xdef}, \.{\\edef} )}
+@d set_box=97 {set a box ( \.{\\setbox} )}
+@d hyph_data=98 {hyphenation data ( \.{\\hyphenation}, \.{\\patterns} )}
+@d set_interaction=99 {define level of interaction ( \.{\\batchmode}, etc.~)}
+@d max_command=99 {the largest command code seen at |big_switch|}
+@y
+@d LR=70 {text direction ( \.{\\beginL}, \.{\\beginR}, \.{\\endL}, \.{\\endR} )}
+@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} )}
+@d set_box_dimen=83 {change dimension of box ( \.{\\wd}, \.{\\ht}, \.{\\dp} )}
+@d set_shape=84 {specify fancy paragraph shape ( \.{\\parshape} )}
+@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 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} )}
+@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} )}
+@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|}
+@z
+
+@x Special form_feed initialization: (232)
+cat_code("\"):=escape; cat_code("%"):=comment;
+@y
+cat_code("\"):=escape; cat_code("%"):=comment;
+cat_code(form_feed):=car_ret;
+@z
+
+@x Date and time: (241)
+Since standard \PASCAL\ cannot provide such information, something special
+is needed. The program here simply specifies July 4, 1776, at noon; but
+users probably want a better approximation to the truth.
+
+@p procedure fix_date_and_time;
+begin time:=12*60; {minutes since midnight}
+day:=4; {fourth day of the month}
+month:=7; {seventh month of the year}
+year:=1776; {Anno Domini}
+end;
+@y
+It uses a {\mc WAITS} monitor call that puts the date in the left 18 bits
+and the time in the right 18 bits.
+
+@p procedure fix_date_and_time;
+var t:integer; {accumulator}
+date:integer; {raw date}
+g:boolean; {garbage}
+begin call_i(@'400101,,t,t,g); {that's \.{ACCTIM}}
+date:=t div @'1000000;
+time:=(t mod @'1000000) div 60;
+day:=(date mod 31)+1;
+month:=((date div 31) mod 12)+1;
+year:=(date div (31*12))+1964;
+end;
+@z
+
+@x Page number maintenance: (304)
+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..max_in_open] of integer|\unskip'
+by analogy with |line_stack|.
+@y
+Similarly, we maintain a global variable |page| and a corresponding
+|page_stack|.
+@z
+@x
+@!line_stack : array[1..max_in_open] of integer;
+@y
+@!line_stack : array[1..max_in_open] of integer;
+@!page : integer; {current page number in the current source file}
+@!page_stack : array[1..max_in_open] of integer;
+@z
+
+@x Printing the page number: (313)
+else begin print_nl("l."); print_int(line);
+@y
+else begin if page>1 then
+ begin print_nl("p."); print_int(page); print(",l.");
+ end
+ else print_nl("l.");
+ print_int(line);
+@z
+
+@x More page number maintenance: (328)
+or |limit| or |line|.
+@y
+or |limit| or |line| or |page|.
+@z
+@x
+line_stack[index]:=line; start:=first; state:=mid_line;
+@y
+line_stack[index]:=line; start:=first; state:=mid_line;
+page_stack[index]:=page;
+@z
+@x
+begin first:=start; line:=line_stack[index];
+@y
+begin first:=start; page:=page_stack[index]; line:=line_stack[index];
+@z
+
+@x More page number printing: (336)
+ print("; all text was ignored after line "); print_int(skip_line);
+@y
+ print("; all text was ignored after line "); print_int(skip_line);
+ if skip_page>1 then
+ begin print(", p."); print_int(skip_page);
+ end;
+@z
+
+@x Pausing on input: (363)
+@ 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 procedure firm_up_the_line;
+var k:0..buf_size; {an index into |buffer|}
+begin limit:=last;
+if pausing>0 then if interaction>nonstop_mode then
+ begin wake_up_terminal; print_ln;
+ if start<limit then for k:=start to limit-1 do print(buffer[k]);
+ first:=limit; prompt_input("=>"); {wait for user response}
+@.=>@>
+ if last>first then
+ begin for k:=first to last-1 do {move line down in buffer}
+ buffer[k+start-first]:=buffer[k];
+ limit:=start+last-first;
+ end;
+ end;
+end;
+@y
+@ 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 in the transcript file, followed by `\.{=>}',
+and also put into the user's line-editor buffer.
+\TeX\ waits for the line to be edited, and the next line received is
+used instead of the line in the file.
+
+@p procedure firm_up_the_line;
+var k:0..buf_size; {an index into |buffer|}
+begin limit:=last;
+if pausing>0 then if interaction>nonstop_mode then
+ if buffer[start]<>form_feed then
+ begin wake_up_terminal; print_ln;
+ if start=limit then {empty line will be made nonempty so that it's visible}
+ begin buffer[start]:=" "; incr(limit);
+ end;
+ decr(selector); {inhibit terminal output temporarily}
+ for k:=start to limit-1 do
+ begin print_char(buffer[k]);
+ pto_chr(xchr[buffer[k]]);
+ end;
+ print("=>"); first:=start;
+ if not input_ln(term_in,true) then
+ fatal_error("End of file on the terminal!");
+@.End of file on the terminal@>
+ if last>first then for k:=first to last-1 do print_char(buffer[k]);
+ limit:=last; print_ln; incr(selector);
+ end;
+end;
+@z
+
+@x Reading the first line of a file: (485)
+@ 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) then read_open[m]:=normal
+else begin a_close(read_file[m]); read_open[m]:=closed;
+ end
+@y
+@ The first line of a file must be treated specially, since |input_ln|
+must be told not to |get|. Furthermore we want to omit the optional file
+directory page present at {\mc SAIL}.
+@^system dependencies@>
+
+@<Input the first line of |read_file[m]|@>=
+if not input_ln(read_file[m],false) then
+ begin a_close(read_file[m]); read_open[m]:=closed;
+ end
+else begin
+ if(last-start=29)and(buffer[start]="C")and(buffer[start+8]=@'26) then
+ begin while (read_file[m]^<>chr(form_feed))and(not eof(read_file[m])) do
+ begin read_ln(read_file[m]); read(read_file[m],aux_buf:temp_ptr);
+ end; {skip the directory}
+ buffer[start]:=form_feed; last:=start+1;
+ end;
+ read_open[m]:=normal;
+ end
+@z
+
+@x Still more page number maintenance: (493)
+where skipping began, for use in error messages.
+
+@<Glob...@>=
+@!skip_line:integer; {skipping began here}
+@y
+where skipping began, for use in error messages. Also the page number.
+
+@<Glob...@>=
+@!skip_line,@!skip_page:integer; {skipping began here}
+@z
+@x
+skip_line:=line;
+@y
+skip_line:=line; skip_page:=page;
+@z
+
+@x Parsing file names: (513)
+@ 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...@>=
+@!area_delimiter:pool_pointer; {the most recent `\.>' or `\.:', if any}
+@!ext_delimiter:pool_pointer; {the relevant `\..', if any}
+@y
+@ The file names we shall deal with have the following structure:
+If the name contains `\.[', the file area consists of all characters
+from this character to the end; otherwise the file area is null.
+If the remaining file name contains `\..', the file extension consists of all
+such characters from this character to the end, otherwise the file extension
+is null. We can assume that there is at most one `\.[' and at most one `\..'.
+@^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...@>=
+@!area_delimiter:pool_pointer; {the most recent `\.[', if any}
+@!ext_delimiter:pool_pointer; {the relevant `\..', if any}
+@z
+@x
+@d TEX_area=="TeXinputs:"
+@.TeXinputs@>
+@d TEX_font_area=="TeXfonts:"
+@.TeXfonts@>
+@y
+@d TEX_area=="[tex,sys]"
+@d TEX_font_area=="[tfm,sys]"
+@z
+@x
+else begin if (c=">")or(c=":") then
+ begin area_delimiter:=pool_ptr; ext_delimiter:=0;
+ end
+ else if (c=".")and(ext_delimiter=0) then ext_delimiter:=pool_ptr;
+@y
+else begin if c="[" then area_delimiter:=pool_ptr
+ else if c="." then ext_delimiter:=pool_ptr;
+@z
+@x
+if area_delimiter=0 then cur_area:=""
+else begin cur_area:=str_ptr; incr(str_ptr);
+ str_start[str_ptr]:=area_delimiter+1;
+ end;
+if ext_delimiter=0 then
+ begin cur_ext:=""; cur_name:=make_string;
+ end
+else begin cur_name:=str_ptr; incr(str_ptr);
+ str_start[str_ptr]:=ext_delimiter; cur_ext:=make_string;
+ end;
+@y
+cur_name:=str_ptr;
+if ext_delimiter=0 then cur_ext:=""
+else begin incr(str_ptr);
+ str_start[str_ptr]:=ext_delimiter; cur_ext:=str_ptr;
+ end;
+if area_delimiter<=str_start[str_ptr] then
+ begin cur_area:=""; incr(str_ptr); str_start[str_ptr]:=pool_ptr;
+ end
+else begin incr(str_ptr);
+ str_start[str_ptr]:=area_delimiter; cur_area:=make_string;
+ end;
+@z
+
+@x Printing file names: (518)
+begin print(a); print(n); print(e);
+@y
+begin print(n); print(e); print(a);
+@z
+
+@x Converting file names to Pascal strings: (519)
+allows both lowercase and uppercase letters in the file name.
+@^system dependencies@>
+
+@d append_to_name(#)==begin c:=#; incr(k);
+@y
+converts lowercase letters to uppercase.
+
+A special convention is used here with respect to font metric files: If the
+file name is longer than six characters (e.g., `\.{helvetica}' or
+`\.{oldenglish}'), we abbreviate it by retaining the first three and
+last three characters (e.g., `\.{helica}' or `\.{oldish}').
+@^system dependencies@>
+
+@d append_to_name(#)==begin c:=#; incr(k);
+ if (c>="a")and(c<="z") then c:=c-@'40; {convert to uppercase}
+@z
+@x
+for j:=str_start[a] to str_start[a+1]-1 do append_to_name(str_pool[j]);
+for j:=str_start[n] to str_start[n+1]-1 do append_to_name(str_pool[j]);
+for j:=str_start[e] to str_start[e+1]-1 do append_to_name(str_pool[j]);
+@y
+if (e=".tfm")and(length(n)>6) then
+ begin for j:=str_start[n] to str_start[n]+2 do
+ append_to_name(str_pool[j]);
+ for j:=str_start[n+1]-3 to str_start[n+1]-1 do
+ append_to_name(str_pool[j]);
+ end
+else for j:=str_start[n] to str_start[n+1]-1 do append_to_name(str_pool[j]);
+for j:=str_start[e] to str_start[e+1]-1 do append_to_name(str_pool[j]);
+for j:=str_start[a] to str_start[a+1]-1 do append_to_name(str_pool[j]);
+@z
+
+@x Parsing file names in the buffer: (520)
+@d format_default_length=20 {length of the |TEX_format_default| string}
+@d format_area_length=11 {length of its area part}
+@d format_ext_length=4 {length of its `\.{.fmt}' part}
+@y
+@d format_default_length=18 {length of the |TEX_format_default| string}
+@d format_area_length=9 {length of its area part}
+@d format_ext_length=4 {length of its `\.{.fmt}' part}
+@z
+@x
+TEX_format_default:='TeXformats:plain.fmt';
+@.TeXformats@>
+@y
+TEX_format_default:='plain.fmt[tex,sys]';
+@z
+@x
+|TEX_format_default|.
+@y
+|TEX_format_default|; but it actually switches stuff around to keep the
+file area last.
+@z
+@x
+@!j:integer; {index into |buffer| or |TEX_format_default|}
+@y
+@!j:integer; {index into |buffer| or |TEX_format_default|}
+@!d:integer; {a kludge}
+@z
+@x
+for j:=1 to n do append_to_name(xord[TEX_format_default[j]]);
+for j:=a to b do append_to_name(buffer[j]);
+for j:=format_default_length-format_ext_length+1 to format_default_length do
+ append_to_name(xord[TEX_format_default[j]]);
+@y
+for j:=a to b do append_to_name(buffer[j]);
+if b=0 then
+ begin d:=format_default_length-format_area_length+1;
+ n:=format_default_length;
+ end
+else d:=format_default_length-format_area_length-format_ext_length+1;
+for j:=d to format_default_length-format_area_length do
+ append_to_name(xord[TEX_format_default[j]]);
+for j:=format_default_length-n+1 to format_default_length do
+ append_to_name(xord[TEX_format_default[j]]);
+@z
+
+@x The real file names: (525)
+@ 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 function make_name_string:str_number;
+var k:1..file_name_size; {index into |name_of_file|}
+begin if (pool_ptr+name_length>pool_size)or(str_ptr=max_strings) then
+ make_name_string:="?"
+else begin for k:=1 to name_length do append_char(xord[name_of_file[k]]);
+ make_name_string:=make_string;
+ end;
+end;
+function a_make_name_string(var f:alpha_file):str_number;
+begin a_make_name_string:=make_name_string;
+end;
+function b_make_name_string(var f:byte_file):str_number;
+begin b_make_name_string:=make_name_string;
+end;
+function w_make_name_string(var f:word_file):str_number;
+begin w_make_name_string:=make_name_string;
+end;
+@y
+@ 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,
+due to David Fuchs, deduces the full name of file~|f| on {\mc WAITS}:
+@^system dependencies@>
+@^Fuchs, David Raymond@>
+
+@p procedure cur_nam(var chan:f@&i@&l@&e;var s:string); extern; @t\2@>@/
+function make_name_string(var f:f@&i@&l@&e):str_number;
+var s:packed array[1..24] of char;
+@!k:1..24; {file names at {\sc SAIL} have at most 23 characters}
+begin if (pool_ptr+24>pool_size)or(str_ptr=max_strings) then
+ make_name_string:="?"
+else begin cur_nam(f,s); k:=1;
+ while ord(s[k])<>0 do
+ begin append_char(xord[s[k]]); incr(k);
+ end;
+ make_name_string:=make_string;
+ end;
+end;
+function a_make_name_string(var f:alpha_file):str_number;
+begin a_make_name_string:=make_name_string(f);
+end;
+function b_make_name_string(var f:byte_file):str_number;
+begin b_make_name_string:=make_name_string(f);
+end;
+function w_make_name_string(var f:word_file):str_number;
+begin w_make_name_string:=make_name_string(f);
+end;
+@z
+
+@x Line editor gets misspelled file name: (530)
+begin if interaction=scroll_mode then wake_up_terminal;
+@y
+@!i:pool_pointer; {index into |str_pool|}
+begin if interaction=scroll_mode then wake_up_terminal;
+@z
+@x
+clear_terminal; prompt_input(": "); @<Scan file name in the buffer@>;
+@y
+clear_terminal; {now we'll fill the line editor's buffer with the old name}
+for i:=str_start[cur_name] to str_start[cur_name+1]-1 do
+ pto_chr(xchr[str_pool[i]]);
+for i:=str_start[cur_ext] to str_start[cur_ext+1]-1 do
+ pto_chr(xchr[str_pool[i]]);
+for i:=str_start[cur_area] to str_start[cur_area+1]-1 do
+ pto_chr(xchr[str_pool[i]]);
+ptwr1w(0,@'214); {control-formfeed returns cursor to start of line}
+prompt_input(": "); @<Scan file name in the buffer@>;
+@z
+
+@x Reading the first line of a file, again: (538)
+@ 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...@>=
+begin if not input_ln(cur_file,false) then do_nothing;
+@y
+@ Here we have to remember to tell |input_ln| not to do the first |get|,
+and we also want to skip over a file directory page. An empty file
+is considered to contain a single blank line.
+@^system dependencies@>
+@^empty line at end of file@>
+
+@<Read the first line...@>=
+begin if input_ln(cur_file,false) then
+ begin if(last-start=29)and(buffer[start]="C")and(buffer[start+8]=@'26) then
+ begin while (cur_file^<>chr(form_feed))and(not eof(cur_file)) do
+ begin read_ln(cur_file); read(cur_file,aux_buf:temp_ptr);
+ end; {skip the directory}
+ buffer[start]:=form_feed; last:=start+1;
+ end;
+ end;
+page:=1;
+@z
+
+@x new DVI opcodes [585-586]
+\yskip\noindent Commands 250--255 are undefined at the present time.
+
+@ @d set_char_0=0 {typeset character 0 and move right}
+@y
+\yskip\hang|begin_reflect| 250. Begin a (possibly recursive) reflected segment.
+
+\yskip\hang|end_reflect| 251. End a (possibly recursive) reflected segment.
+
+\yskip\noindent Commands 250--255 are undefined in normal \.{DVI} files,
+but 250 and 251 are permitted in the special `\.{DVI-IVD}' files
+produced by this variant of \TeX.
+
+@ @d begin_reflect=250 {begin a reflected segment (not normally allowed)}
+@d end_reflect=251 {end a reflected segment (not normally allowed)}
+@d set_char_0=0 {typeset character 0 and move right}
+@z
+
+@x The DVI output buffer: (594)
+@!dvi_index=0..dvi_buf_size; {an index into the output buffer}
+@y
+@!dvi_index=0..dvi_buf_size; {an index into the output buffer}
+@!packed_bytes=packed array[dvi_index] of eight_bits;
+ {buffer for \.{DVI} output}
+@z
+@x
+@!dvi_buf:array[dvi_index] of eight_bits; {buffer for \.{DVI} output}
+@y
+@!dvi_buf:packed_bytes; {buffer for \.{DVI} output}
+@z
+@x
+@p procedure write_dvi(@!a,@!b:dvi_index);
+var k:dvi_index;
+begin for k:=a to b do write(dvi_file,dvi_buf[k]);
+end;
+@y
+@p procedure ary_out(var f:file;@!b:packed_bytes; @!o,@!c:integer);
+ extern;@t\2@>@#
+procedure write_dvi(@!a,@!b:dvi_index);
+begin ary_out(dvi_file,dvi_buf,a div 4,(b+1-a)div 4);
+end;
+@z
+
+@x changes to ship_out [638]
+begin if tracing_output>0 then
+@y
+begin LR_ptr:=get_avail; info(LR_ptr):=0; {|begin_L_code| at outer level}
+if tracing_output>0 then
+@z
+@x (module 639)
+flush_node_list(p);
+@y
+flush_node_list(p); @<Flush the LR stack@>;
+@z
+
+@x "r DVIdover": (642)
+ b_close(dvi_file);
+@y
+ b_close(dvi_file);
+ if pseudo_typein=0 then
+ begin k:=selector; selector:=new_string;
+ pool_ptr:=str_start[str_ptr];
+ print("r DVIdover;"); print(output_file_name);
+ selector:=k;
+ if pool_ptr<pool_size then
+ if str_ptr<max_strings then {|overflow| can't occur}
+ pseudo_typein:=make_string;
+ end;
+@z
+
+@x hpack changes [649]
+begin r:=get_node(box_node_size); type(r):=hlist_node;
+@y
+@!LR_ptr,@!LR_tmp:pointer; {for LR stack maintenance}
+@!LR_problems:integer; {counts missing begins and ends}
+begin LR_ptr:=null; LR_problems:=0;
+r:=get_node(box_node_size); type(r):=hlist_node;
+@z
+@x (module 649, continued)
+exit: hpack:=r;
+@y
+exit: @<Check for LR anomalies at the end of |hpack|@>;
+hpack:=r;
+@z
+
+@x Page numbers on over/underfull box messages: (663)
+ print_int(line);
+@y
+ print_int(line);
+ if page>1 then
+ begin print(", p."); print_int(page);
+ end;
+@z
+@x
+ print_int(line);
+@y
+ print_int(line);
+ if page>1 then
+ begin print(", p."); print_int(page);
+ end;
+@z
+
+@x post_line_break stuff [877]
+begin @<Reverse the links of the relevant passive nodes, setting |cur_p| to the
+@y
+@!LR_ptr,@!LR_tmp:pointer; {for LR stack maintenance}
+begin LR_ptr:=null;
+ @<Reverse the links of the relevant passive nodes, setting |cur_p| to the
+@z
+@x (module 877, continued)
+prev_graf:=best_line-1;
+@y
+prev_graf:=best_line-1;
+@<Flush the LR stack@>;
+@z
+@x (module 880)
+@<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|@>;
+@y
+@<Insert LR nodes at the beginning of the current line@>;
+@<Adjust the LR stack based on LR nodes in this line@>;
+@<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|@>;
+@<Insert LR nodes at the end of the current line@>;
+@z
+
+@x new horizontal command [1090]
+ vmode+ex_space:@t@>@;@/
+@y
+ vmode+ex_space,vmode+LR:@t@>@;@/
+@z
+
+@x math in text is L-text [module 1196]
+begin tail_append(new_math(math_surround,before));
+@y
+begin tail_append(new_math(math_surround,before));
+@<Append a |begin_L| to the tail of the current list@>;
+@z
+@x (module 1196, continued)
+tail_append(new_math(math_surround,after));
+@y
+@<Append an |end_L| to the tail of the current list@>;
+tail_append(new_math(math_surround,after));
+@z
+
+@x The endgame: (1335)
+@<Last-minute...@>=
+@y
+The new stuff at {\mc SAIL} has to do with preparing for what the user
+presumably wants to do next, by typing it for him/her.
+
+@<Last-minute...@>=
+@z
+@x
+end;
+@y
+if (pseudo_typein<>0)and(interaction>batch_mode) then
+ begin write_ln(term_out);
+ for k:=str_start[pseudo_typein] to str_start[pseudo_typein+1]-1 do
+ pto_chr(xchr[str_pool[k]]);
+ end;
+end;
+@z
+
+@x whatsit processing [1341]
+@d special_node=3 {|subtype| in whatsits that represent \.{\\special} things}
+@y
+@d special_node=3 {|subtype| in whatsits that represent \.{\\special} things}
+@d LR_node=4 {|subtype| in whatsits that represent \.{\\beginL}, etc.}
+@d LR_type(#)==mem[#+1].int {the sub-subtype}
+@z
+@x (module 1344)
+@d immediate_code=4 {command modifier for \.{\\immediate}}
+
+@<Put each...@>=
+@y
+@d immediate_code=4 {command modifier for \.{\\immediate}}
+@d begin_L_code=0 {command modifier for \.{\\beginL}}
+@d begin_R_code=1 {command modifier for \.{\\beginR}}
+@d end_L_code=2 {command modifier for \.{\\endL}}
+@d end_R_code=3 {command modifier for \.{\\endR}}
+@d begin_LR(#)==(LR_type(#)<end_L_code)
+@d begin_LR_type(#)==(LR_type(#)-end_L_code)
+
+@<Put each...@>=
+primitive("beginL",LR,begin_L_code);@/
+@!@:begin_L_}{\.{\\beginL} primitive@>
+primitive("beginR",LR,begin_R_code);@/
+@!@:begin_R_}{\.{\\beginR} primitive@>
+primitive("endL",LR,end_L_code);@/
+@!@:end_L_}{\.{\\endL} primitive@>
+primitive("endR",LR,end_R_code);@/
+@!@:end_R_}{\.{\\endR} primitive@>
+@z
+@x (module 1346)
+@ @<Cases of |print_cmd_chr|...@>=
+@y
+@ @<Cases of |print_cmd_chr|...@>=
+LR: case chr_code of
+begin_L_code: print_esc("beginL");
+begin_R_code: print_esc("beginR");
+end_L_code: print_esc("endL");
+othercases print_esc("endR")
+endcases;
+@z
+@x (module 1356)
+othercases print("whatsit?")
+@y
+LR_node: case LR_type(p) of
+begin_L_code: print_esc("beginL");
+begin_R_code: print_esc("beginR");
+end_L_code: print_esc("endL");
+othercases print_esc("endR")
+endcases;
+othercases print("whatsit?")
+@z
+@x (module 1357)
+close_node: begin r:=get_node(small_node_size); words:=small_node_size;
+@y
+close_node,LR_node: begin r:=get_node(small_node_size); words:=small_node_size;
+@z
+@x (module 1358)
+close_node: free_node(p,small_node_size);
+@y
+close_node,LR_node: free_node(p,small_node_size);
+@z
+@x (module 1360)
+@ @<Incorporate a whatsit node into an hbox@>=do_nothing
+@y
+@ @<Incorporate a whatsit node into an hbox@>=
+if subtype(p)=LR_node then @<Adjust the LR stack for the |hpack| routine@>
+@z
+@x (module 1366)
+@ @<Output the whatsit node |p| in an hlist@>=
+out_what(p)
+@y
+@ @<Output the whatsit node |p| in an hlist@>=
+if subtype(p)<>LR_node then out_what(p)
+else @<Output a reflection instruction if the direction has changed@>
+@z
+
+@x Final system-dependent changes: [1376]
+This section should be replaced, if necessary, by changes to 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@>
+@y
+Now we do the main work required for mixed-direction texts.
+
+@<Cases of |main_control| that build...@>=
+hmode+LR: begin new_whatsit(LR_node,small_node_size); LR_type(tail):=cur_chr;
+ end;
+mmode+LR: report_illegal_case;
+
+@ @<Glob...@>=
+@!LR_ptr,@!LR_tmp:pointer; {stack of LR codes and temp for manipulation}
+
+@ @<Declare functions needed for special kinds of nodes@>=
+function new_LR(@!s:small_number): pointer;
+var p: pointer; {the new node}
+begin p:=get_node(small_node_size); type(p):=whatsit_node; subtype(p):=LR_node;
+LR_type(p):=s; new_LR:=p;
+end;
+
+@ @<Declare functions needed for special kinds of nodes@>=
+function safe_info(@!p:pointer): integer;
+begin if p=null then safe_info:=-1@+else safe_info:=info(p);
+end;
+
+@ @<Append a |begin_L| to the tail of the current list@>=
+tail_append(new_LR(begin_L_code))
+
+@ @<Append an |end_L| to the tail of the current list@>=
+tail_append(new_LR(end_L_code))
+
+@ A number of routines are based on a stack of one-word nodes whose |info|
+fields contain either |begin_L_code| or |begin_R_code|. The top of the
+stack is pointed to by |LR_ptr|, and an auxiliary variable |LR_tmp| is
+available for stack manipulation.
+
+@d push_LR(#)==begin LR_tmp:=get_avail; info(LR_tmp):=LR_type(#);
+ link(LR_tmp):=LR_ptr; LR_ptr:=LR_tmp;
+ end
+@d pop_LR==begin LR_tmp:=LR_ptr; LR_ptr:=link(LR_tmp); free_avail(LR_tmp);
+ end
+
+@<Flush the LR stack@>=while LR_ptr<>null do pop_LR
+
+@ @<Insert LR nodes at the beginning of the current line@>=
+while LR_ptr<>null do
+ begin LR_tmp:=new_LR(info(LR_ptr)); link(LR_tmp):=link(temp_head);
+ link(temp_head):=LR_tmp; pop_LR;
+ end
+
+@ @<Adjust the LR stack based on LR nodes in this line@>=
+q:=link(temp_head);
+while q<>cur_break(cur_p) do
+ begin if notis_char_node(q) then if type(q)=whatsit_node then
+ if subtype(q)=LR_node then
+ if begin_LR(q) then push_LR(q)
+ else if LR_ptr<>null then
+ if info(LR_ptr)=begin_LR_type(q) then pop_LR;
+ q:=link(q);
+ end
+
+@ We use the fact that |q| now points to the node with \.{\\rightskip} glue.
+
+@<Insert LR nodes at the end of the current line@>=
+if LR_ptr<>null then
+ begin s:=temp_head; r:=link(s);
+ while r<>q do
+ begin s:=r; r:=link(s);
+ end;
+ r:=LR_ptr;
+ while r<>null do
+ begin LR_tmp:=new_LR(info(r)+end_L_code);
+ link(s):=LR_tmp; s:=LR_tmp; r:=link(r);
+ end;
+ link(s):=q;
+ end
+
+@ @<Adjust the LR stack for the |hpack| routine@>=
+if begin_LR(p) then push_LR(p)
+else if safe_info(LR_ptr)=begin_LR_type(p) then pop_LR
+else begin incr(LR_problems);
+ while link(q)<>p do q:=link(q);
+ link(q):=link(p); free_node(p,small_node_size); p:=q;
+ end
+
+@ @<Check for LR anomalies at the end of |hpack|@>=
+if LR_ptr<>null then
+ begin while link(q)<>null do q:=link(q);
+ repeat link(q):=new_LR(info(LR_ptr)+end_L_code); q:=link(q);
+ LR_problems:=LR_problems+10000; pop_LR;
+ until LR_ptr=null;
+ end;
+if LR_problems>0 then
+ begin print_ln; print_nl("\endL or \endR problem (");@/
+ print_int(LR_problems div 10000); print(" missing, ");@/
+ print_int(LR_problems mod 10000); print(" extra");@/
+ LR_problems:=0; goto common_ending;
+ end
+
+@ @<Output a reflection instruction if the direction has changed@>=
+if begin_LR(p) then
+ begin if safe_info(LR_ptr)<>LR_type(p) then
+ begin synch_h; synch_v; dvi_out(begin_reflect);
+ end;
+ push_LR(p);
+ end
+else if safe_info(LR_ptr)=begin_LR_type(p) then
+ begin pop_LR;
+ if info(LR_ptr)+end_L_code<>LR_type(p) then
+ begin synch_h; synch_v; dvi_out(end_reflect);
+ end;
+ end
+else confusion("LR")
+@:this can't happen LR}{\quad LR@>
+
+
+@ Finally, here are the remaining things needed to make the implementation
+complete at {\mc SAIL}.
+@^system dependencies@>
+
+@ The |pseudo_typein| variable is set nonzero if the |error| routine
+uses the `\.E' option to exit and edit.
+
+@<Glob...@>=
+@!pseudo_typein:str_number;
+
+@ @<Set init...@>=
+pseudo_typein:=0; page:=0;
+
+@ The |mem| array is declared after the other global variables, so
+that our friendly \PASCAL\ will compile things correctly.
+
+@<Glob...@>=
+@!mem : array[mem_min..mem_max] of memory_word; {the big dynamic storage area}
+@z