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+Date: 8 Jan 90 Message No: 022
+Resent: 11 Jan 90
+
+To: TeX implementors and distributors
+
+From: Barbara Beeton
+
+Subject: Updates: files at labrea, TEX82.BUG, Knuth off-line
+
+
+[ The initial mailing of this message and the TEX82.BUG file, in three
+ parts, caused our mailer to suffer a serious breakdown; not only were
+ my messages not delivered, but the entire mail server crashed, putting
+ the whole Society out of the mail business for two days. In order to
+ recover in the most painless manner possible, I have made the recommended
+ changes in the mailing list, and am re-sending the whole lot. Please
+ accept my apologies if you get two copies of anything. The only change
+ to any of them is the addition of the Resent: date at the top of this
+ message, and this paragraph. ]
+
+Preparing this installment has taken rather longer than I intended,
+delayed by standards meetings, the holidays, and writing the user
+documentation for the impending release of version 2.0 of both AMS-TeX
+and the AMSFonts collection. It is my understanding that the AMS
+management wishes these two packages to have the widest distribution
+possible, so an announcement should be forthcoming to make them both
+available to TeX distributors and archives for inclusion in their
+offerings. (The AMSFonts package will not include the .mf sources;
+those will be available only by individual request, and there wil be
+some restrictions. If you are interesed in the .mf sources, write to
+Regina Girouard, rmg@math.ams.com; she is Manager of the AMS Composition
+Services Department, in charge of the font distribution.) Stay tuned.
+
+There have been no updates to the TeX "core" at labrea.stanford.edu
+since November. On the assumption that TUGboat 10 #4 (the Proceedings
+of this summer's tenth anniversary meeting) would be out and in your
+hands by now, I had not sent out the updates to the TEX82.BUG file,
+since it is very large, and all entries since the beginning of 1989
+are printed in their entirety in a supplement accompanying that issue.
+However, since there have been a number of delays in its production (it
+was sent to the printer the first week of November), and the projected
+mailing date now isn't until late January, I am sending under separate
+cover, in two pieces, the additions that haven't been sent out before
+in this form, items 355-370. (They "duplicate" the code in the TEX.WEB
+differences file that was sent early in November, as a supplement to
+message 20.) Since preparing the camera copy for the TUGboat supplement,
+two additional bug listings, 371 and 372, have come to my attention.
+371 is in response to a bug found by Wayne Sullivan, and Knuth distributed
+372 in TeXhax 89 #110. Both are reproduced below. The TEX.WEB file
+incorporating them has not yet appeared at labrea, as mentioned earlier.
+This is the commentary that came with 371 (dated 24 Nov 89); it sounds
+like caution is in order when applying it:
+
+ Here's how I plan to fix the problem. The code isn't tested yet --- I'll
+ wait a couple weeks to see if I can combine it with some other work ---
+ but I think it catches all cases where scanning can interfere with
+ the save_stack protocols. It preserves the locality of csnaming, and
+ makes things like \discretionary consistent with \insert in this respect.
+
+And here is the text that accompanied #372; again, caution:
+
+ I just received a message from Rainer Sch\"opf and Frank Mittelbach
+ in Gutenberg's city (Mainz) that they've done it again, found another
+ subtle bug. This one is especially unique because it will not be
+ detected in the TRIP test; it only occurs in the system-dependent code
+ that figures out the "area" and "extension" part of a file name.
+
+ As far as I know, the error occurs only when you try to combine
+ \csname somehow with file name specification; for example,
+ \input area:file.ext\csname xyz\endcsname
+ will fail on many systems. (Reason: TeX may have to store the
+ control sequence name xyz, while it's looking for the token following
+ "ext". This moves things in the string pool; but the present TeX doesn't
+ move the area and extension pointers, so they might point to garbage.)
+
+ This bug will be corrected in version 2.993, but I decided to use
+ TeXhax to let installers get a head start, since this bug affects
+ nearly everybody's system-dependent code! The changes are simple---
+ so simple I haven't even felt the need to test them yet---but they
+ should be made, and you can get a head start by putting them into
+ your change files before you get a new TEX.WEB file.
+
+ Here are the changes I'll be making to TEX.WEB (unless there's
+ an error here, which cannot be:)
+
+Brian Hamilton Kelly pointed out that identifiers in TEX.WEB containing
+a cap "E" (in his case, from local changes to support editors) get the
+"E" lowered as it is in TeX, and suggested that perhaps this should be
+fixed directly in the .WEB file. We'd made a local change for that here
+at AMS some years ago, so I forwarded the code to Brian. I also sent
+it to Don Knuth, who replied that he didn't think it appropriate in the
+canonical TEX.WEB, but suggested that I forward the code to this list.
+The solution isn't perfect -- it only suppresses the problem if the "E"
+doesn't precede an "X" -- but it's a start. If anyone has a better
+solution, please send it to me and i'll distribute it to the list.
+The code is given below.
+
+Peter Breitenlohner has provided a list of modules in MF.WEB 1.8 that
+have changed, as compared to 1.7; see below. I have not yet retrieved
+the source from labrea so that a difference list can be run, but it's
+on my list.
+
+Finally, it's now official -- Knuth has withdrawn from the electronic
+networks, and will henceforth be accessible only via the postal service.
+However, he has deputized me to keep an eye out for genuine bugs (as
+reported through TeXhax, UKTeX, etc.) and has agreed to let his secretary
+accept electronic messages from me. Mail sent to Knuth's old address at
+Sail will now yield the following result:
+
+ Subject: Failed mail returned: user not accepting mail
+
+ The message below was not deliverable to:
+
+ DEK@SAIL.Stanford.EDU
+
+ DEK (Don Knuth) has decided to discontinue reading email.
+ Please write to him at the following address:
+
+ Donald E. Knuth
+ Professor of The Art of Computer Programming
+ Computer Science Department
+ Stanford University
+ Stanford, CA 94305-2140 USA
+
+If you have a bug to report and you would like me to forward it, I will.
+Alternatively, you can send your report on paper to Knuth's new address.
+
+
+########################################################################
+
+Addenda to TEX82.BUG -- items 371 and 372
+
+371. Prevent save_stack conflicts, e.g. in {\hbox\expandafter{\csname
+ \endcsname}} (found by Sullivan).
+@x module 645
+@p procedure scan_spec; {scans a box specification and left brace}
+label found;
+begin if scan_keyword("to") then saved(0):=exactly
+@.to@>
+else if scan_keyword("spread") then saved(0):=additional
+@.spread@>
+else begin saved(0):=additional; saved(1):=0;
+ goto found;
+ end;
+scan_normal_dimen; saved(1):=cur_val;
+found: save_ptr:=save_ptr+2; scan_left_brace;
+@y
+@p procedure scan_spec(@!c:group_code;@!three_codes:boolean);
+ {scans a box specification and left brace}
+label found;
+var @!s:integer; {temporarily saved value}
+@!spec_code:exactly..additional;
+begin if three_codes then s:=saved(0);
+if scan_keyword("to") then spec_code:=exactly
+@.to@>
+else if scan_keyword("spread") then spec_code:=additional
+@.spread@>
+else begin spec_code:=additional; cur_val:=0;
+ goto found;
+ end;
+scan_normal_dimen;
+found: if three_codes then
+ begin saved(0):=s; incr(save_ptr);
+ end;
+saved(0):=spec_code; saved(1):=cur_val; save_ptr:=save_ptr+2;
+new_save_level(c); scan_left_brace;
+@z
+@x module 774
+scan_spec; new_save_level(align_group);@/
+@y
+scan_spec(align_group,false);@/
+@z
+@x module 1073
+ if t=0 then saved(0):=cur_val@+else saved(0):=-cur_val;
+ scan_box;
+ end;
+any_mode(leader_ship): begin saved(0):=leader_flag-a_leaders+cur_chr; scan_box;
+ end;
+any_mode(make_box): begin saved(0):=0; begin_box;
+ end;
+@y
+ if t=0 then scan_box(cur_val)@+else scan_box(-cur_val);
+ end;
+any_mode(leader_ship): scan_box(leader_flag-a_leaders+cur_chr);
+any_mode(make_box): begin_box(0);
+@z
+@x module 1075
+procedure box_end;
+var p:pointer; {|ord_noad| for new box in math mode}
+begin if saved(0)<box_flag then @<Append box |cur_box| to the current list,
+ shifted by |saved(0)|@>
+else if saved(0)<ship_out_flag then @<Store \(c)|cur_box| in a box register@>
+else if cur_box<>null then
+ if saved(0)>ship_out_flag then @<Append a new leader node that
+ uses |cur_box|@>
+@y
+procedure box_end(@!box_context:integer);
+var p:pointer; {|ord_noad| for new box in math mode}
+begin if box_context<box_flag then @<Append box |cur_box| to the current list,
+ shifted by |box_context|@>
+else if box_context<ship_out_flag then @<Store \(c)|cur_box| in a box register@>
+else if cur_box<>null then
+ if box_context>ship_out_flag then @<Append a new leader node that
+ uses |cur_box|@>
+@z
+@x module 1076
+ begin shift_amount(cur_box):=saved(0);
+@y
+ begin shift_amount(cur_box):=box_context;
+@z
+@x module 1077
+if saved(0)<box_flag+256 then
+ eq_define(box_base-box_flag+saved(0),box_ref,cur_box)
+else geq_define(box_base-box_flag-256+saved(0),box_ref,cur_box)
+@y
+if box_context<box_flag+256 then
+ eq_define(box_base-box_flag+box_context,box_ref,cur_box)
+else geq_define(box_base-box_flag-256+box_context,box_ref,cur_box)
+@z
+@x module 1078
+ begin append_glue; subtype(tail):=saved(0)-(leader_flag-a_leaders);
+@y
+ begin append_glue; subtype(tail):=box_context-(leader_flag-a_leaders);
+@z
+@x module 1079
+procedure begin_box;
+@y
+procedure begin_box(@!box_context:integer);
+@z
+@x ibid
+box_end; {in simple cases, we use the box immediately}
+@y
+box_end(box_context); {in simple cases, we use the box immediately}
+@z
+@x module 1083
+incr(save_ptr); scan_spec;
+if k=hmode then
+ if (saved(-3)<box_flag)and(abs(mode)=vmode) then
+ new_save_level(adjusted_hbox_group)
+ else new_save_level(hbox_group)
+else begin if k=vmode then new_save_level(vbox_group)
+ else begin new_save_level(vtop_group); k:=vmode;
+@y
+saved(0):=box_context;
+if k=hmode then
+ if (box_context<box_flag)and(abs(mode)=vmode) then
+ scan_spec(adjusted_hbox_group,true)
+ else scan_spec(hbox_group,true)
+else begin if k=vmode then scan_spec(vbox_group,true)
+ else begin scan_spec(vtop_group,true); k:=vmode;
+@z
+@x module 1084
+procedure scan_box; {the next input should specify a box or perhaps a rule}
+begin @<Get the next non-blank non-relax...@>;
+if cur_cmd=make_box then begin_box
+else if (saved(0)>=leader_flag)and((cur_cmd=hrule)or(cur_cmd=vrule)) then
+ begin cur_box:=scan_rule_spec; box_end;
+@y
+procedure scan_box(@!box_context:integer);
+ {the next input should specify a box or perhaps a rule}
+begin @<Get the next non-blank non-relax...@>;
+if cur_cmd=make_box then begin_box(box_context)
+else if (box_context>=leader_flag)and((cur_cmd=hrule)or(cur_cmd=vrule)) then
+ begin cur_box:=scan_rule_spec; box_end(box_context);
+@z
+@x module 1086
+pop_nest; box_end;
+@y
+pop_nest; box_end(saved(0));
+@z
+@x module 1117
+else begin incr(save_ptr); saved(-1):=0; scan_left_brace;
+ new_save_level(disc_group); push_nest; mode:=-hmode; space_factor:=1000;
+@y
+else begin incr(save_ptr); saved(-1):=0; new_save_level(disc_group);
+ scan_left_brace; push_nest; mode:=-hmode; space_factor:=1000;
+@z
+@x module 1119
+incr(saved(-1)); scan_left_brace; new_save_level(disc_group);
+@y
+incr(saved(-1)); new_save_level(disc_group); scan_left_brace;
+@z
+@x module 1167
+mmode+vcenter: begin scan_spec; new_save_level(vcenter_group); normal_paragraph;
+@y
+mmode+vcenter: begin scan_spec(vcenter_group,false); normal_paragraph;
+@z
+@x module 1172
+scan_left_brace; push_math(math_choice_group);
+@y
+push_math(math_choice_group); scan_left_brace;
+@z
+@x module 1174
+incr(saved(-1)); scan_left_brace; push_math(math_choice_group);
+@y
+incr(saved(-1)); push_math(math_choice_group); scan_left_brace;
+@z
+@x module 1241
+ if global then saved(0):=box_flag+256+cur_val
+ else saved(0):=box_flag+cur_val;
+ scan_optional_equals; scan_box;
+@y
+ if global then n:=256+cur_val@+else n:=cur_val;
+ scan_optional_equals; scan_box(box_flag+n);
+@z
+
+372. Bugfix 339 didn't go far enough (found by Sch\"opf and Mittelbach).
+@x module 516 [NOTE: THIS AFFECTS ALMOST ALL CHANGE FILES!]
+@ And here's the second.
+@^system dependencies@>
+
+@p function more_name(@!c:ASCII_code):boolean;
+begin if c=" " then more_name:=false
+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;
+ str_room(1); append_char(c); {contribute |c| to the current string}
+@y
+@ And here's the second. The string pool might change as the file name is
+being scanned, since a new \.{\\csname} might be entered; therefore we keep
+|area_delimiter| and |ext_delimiter| relative to the beginning of the current
+string, instead of assigning an absolute address like |pool_ptr| to them.
+@^system dependencies@>
+
+@p function more_name(@!c:ASCII_code):boolean;
+begin if c=" " then more_name:=false
+else begin str_room(1); append_char(c); {contribute |c| to the current string}
+ if (c=">")or(c=":") then
+ begin area_delimiter:=cur_length; ext_delimiter:=0;
+ end
+ else if (c=".")and(ext_delimiter=0) then ext_delimiter:=cur_length;
+@z
+@x module 517 [NOTE: THIS DOES TOO, AND SO DOES THE NEXT!]
+else begin cur_area:=str_ptr; incr(str_ptr);
+ str_start[str_ptr]:=area_delimiter+1;
+@y
+else begin cur_area:=str_ptr;
+ str_start[str_ptr+1]:=str_start[str_ptr]+area_delimiter; incr(str_ptr);
+@z
+@x ibid
+else begin cur_name:=str_ptr; incr(str_ptr);
+ str_start[str_ptr]:=ext_delimiter; cur_ext:=make_string;
+@y
+else begin cur_name:=str_ptr;
+ str_start[str_ptr+1]:=str_start[str_ptr]+ext_delimiter-area_delimiter-1;
+ incr(str_ptr); cur_ext:=make_string;
+@z
+
+
+########################################################################
+
+Change to TEX.WEB (and others) to avoid dropped E in identifiers
+
+@x [0] (AMS) Avoid dropped E in identifiers other than TeX
+\def\drop{\kern-.1667em\lower.5ex\hbox{E}\kern-.125em} % middle of TeX
+\catcode`E=13 \uppercase{\def E{e}}
+\def\\#1{\hbox{\let E=\drop\it#1\/\kern.05em}} % italic type for identifiers
+@y
+\def\drop{\kern-.1667em\lower.5ex\hbox{E}\kern-.125em} % middle of TeX
+\def\cape#1{\if X#1\drop\else E\fi#1} % other E's in identifiers
+\catcode`E=13 \uppercase{\def E{e}}
+\def\\#1{\hbox{\let E=\cape\it#1\/\kern.05em}} % italic type for identifiers
+@z
+
+
+########################################################################
+
+% List of changed modules in MF.WEB 1.8 (as compared to 1.7)
+% Peter Breitenlohner
+
+% The [c]'s refer to the parts of the book `METAFONT: The Program'
+
+limbo
+[1] m.2, 11, 14
+[2] m.17-19, 21-23
+[3] m.30, 34
+[4] m.37-38, 41, 45, 47-49
+[5] m.59-60, 66
+[6] m.85
+[10] m.158-159
+[12] m.186, 190, 192-193, 198-199
+[13] m.200, 210-212
+[14] m.223
+[21] m.402, 410-412, 415-417, 422, 424-425, 436
+[24] m.493
+[35] m.717
+[38] m.774-775, 784
+[41] m.883
+[42] m.912-913, 976-977
+[45] m.1093, 1096-1097, 1103-1112, 1134-1141
+[47] m.1160
+[48] m.1192-1193, 1195, 1200
+[49] m.1204-1205
+
+
+########################################################################
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% Character code reference
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% Upper case letters: ABCDEFGHIJKLMNOPQRSTUVWXYZ
+% Lower case letters: abcdefghijklmnopqrstuvwxyz
+% Digits: 0123456789
+% Square, curly, angle braces, parentheses: [] {} <> ()
+% Backslash, slash, vertical bar: \ / |
+% Punctuation: . ? ! , : ;
+% Underscore, hyphen, equals sign: _ - =
+% Quotes--right left double: ' ` "
+%"at", "number" "dollar", "percent", "and": @ # $ % &
+% "hat", "star", "plus", "tilde": ^ * + ~
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+[ end of message 022 ]
+
+355. String startup problems (Wayne Sullivan, 17 Jul 89)
+@x module 31 (Warning: This affects most change files!)
+ overflow("buffer size",buf_size);
+@:TeX capacity exceeded buffer size}{\quad buffer size@>
+@y
+ @<Report overflow of the input buffer, and abort@>;
+@z
+@x module 35
+consist of the remainder of the command line, after the part that invoked
+\TeX.
+@y
+consist of the remainder of the command line, after the part that invoked
+\TeX.
+
+The first line is special also because it may be read before \TeX\ has
+input a format file. In such cases, normal error messages cannot yet
+be given. The following code uses concepts that will be explained later.
+
+@<Report overflow of the input buffer, and abort@>=
+if format_ident=0 then
+ begin write_ln(term_out,'Buffer size exceeded!'); goto final_end;
+@.Buffer size exceeded@>
+ end
+else begin cur_input.loc_field:=first; cur_input.limit_field:=last-1;
+ overflow("buffer size",buf_size);
+@:TeX capacity exceeded buffer size}{\quad buffer size@>
+ end
+@z
+@x module 1310
+k:=pool_ptr-4; undump_four_ASCII
+@y
+k:=pool_ptr-4; undump_four_ASCII;
+init_str_ptr:=str_ptr; init_pool_ptr:=pool_ptr
+@z
+@x module 1332
+tini@/
+@y
+init_str_ptr:=str_ptr; init_pool_ptr:=pool_ptr; fix_date_and_time;
+tini@/
+@z
+@x module 1332
+init_str_ptr:=str_ptr; init_pool_ptr:=pool_ptr;@/
+@y
+@z
+
+356. Allow integer products to be 31 bits long (Mittelbach, 16 Aug 89)
+@x module 105
+@p function nx_plus_y(@!n:integer;@!x,@!y:scaled):scaled;
+begin if n<0 then
+ begin negate(x); negate(n);
+ end;
+if n=0 then nx_plus_y:=y
+else if ((x<=(@'7777777777-y) div n)and(-x<=(@'7777777777+y) div n)) then
+ nx_plus_y:=n*x+y
+else begin arith_error:=true; nx_plus_y:=0;
+ end;
+end;
+@y
+@d nx_plus_y(#)==mult_and_add(#,@'7777777777)
+@d mult_integers(#)==mult_and_add(#,0,@'17777777777)
+
+@p function mult_and_add(@!n:integer;@!x,@!y,@!max_answer:scaled):scaled;
+begin if n<0 then
+ begin negate(x); negate(n);
+ end;
+if n=0 then mult_and_add:=y
+else if ((x<=(max_answer-y) div n)and(-x<=(max_answer+y) div n)) then
+ mult_and_add:=n*x+y
+else begin arith_error:=true; mult_and_add:=0;
+ end;
+end;
+@z
+@x module 1240
+ if q=multiply then cur_val:=nx_plus_y(eqtb[l].int,cur_val,0)
+@y
+ if q=multiply then
+ if p=int_val then cur_val:=mult_integers(eqtb[l].int,cur_val)
+ else cur_val:=nx_plus_y(eqtb[l].int,cur_val,0)
+@z
+
+357. Raise the maximum number of tokens normally shown (pointed out by
+John Lavagnino in TeXhax on 19 May 89; corrected on 31 Aug 89).
+@x module 295
+begin if p<>null then show_token_list(link(p),null,1000);
+@y
+begin if p<>null then show_token_list(link(p),null,10000000);
+@z
+@x module 1370 (this part of the change is cosmetic only)
+show_token_list(link(def_ref),null,10000000); print_ln;
+@y
+token_show(def_ref); print_ln;
+@z
+
+358. Like 353, but with $$\begingroup\eqno$$ (Mittelbach, 25 Jul 89)
+@x module 1140
+mmode+eq_no: if privileged then start_eq_no;
+@y
+mmode+eq_no: if privileged then
+ if cur_group=math_shift_group then start_eq_no
+ else off_save;
+@z
+
+359. Major extension to 8-bit character input. (These changes, and a few that
+follow, were discussed during the 10th TUG meeting and installed during
+the week of 10 Sep 1989. They bring the implementation of TeX82 up to date with
+international developments and experience, and I believe they mark the
+final development of this program into a completely stable system.)
+Several changes to the documentation (not the program) are omitted here.
+@x module 18
+@!ASCII_code=0..127; {seven-bit numbers}
+@y
+@!ASCII_code=0..255; {eight-bit numbers}
+@z
+@x module 19
+@d last_text_char=127 {ordinal number of the largest element of |text_char|}
+
+@<Local variables for init...@>=
+@!i:0..last_text_char;
+@y
+@d last_text_char=255 {ordinal number of the largest element of |text_char|}
+
+@<Local variables for init...@>=
+@!i:integer;
+@z
+@x module 21
+xchr[0]:=' '; xchr[@'177]:=' ';
+ {ASCII codes 0 and |@'177| do not appear in text}
+@y
+@z
+@x module 23
+for i:=1 to @'37 do xchr[i]:=' ';
+@y changing ' ' to chr(i) here will allow all 8-bit characters to get in
+for i:=0 to @'37 do xchr[i]:=' ';
+for i:=@'177 to @'377 do xchr[i]:=' ';
+@z
+@x module 24
+for i:=1 to @'176 do xord[xchr[i]]:=i;
+@y
+for i:=@'200 to @'377 do xord[xchr[i]]:=i;
+for i:=0 to @'176 do xord[xchr[i]]:=i;
+@z
+@x module 38
+@<Types...@>=
+@!pool_pointer = 0..pool_size; {for variables that point into |str_pool|}
+@!str_number = 0..max_strings; {for variables that point into |str_start|}
+
+@ @<Glob...@>=
+@!str_pool:packed array[pool_pointer] of ASCII_code; {the characters}
+@y [OK to make si(#)==#-128 and so(#)==#+128 (without parens) in change files]
+Some \PASCAL\ compilers won't pack integers into a single byte unless the
+integers lie in the range |-128..127|. To accommodate such systems
+we access the string pool only via macros that can easily be redefined.
+
+@d si(#) == # {convert from |ASCII_code| to |packed_ASCII_code|}
+@d so(#) == # {convert from |packed_ASCII_code| to |ASCII_code|}
+
+@<Types...@>=
+@!pool_pointer = 0..pool_size; {for variables that point into |str_pool|}
+@!str_number = 0..max_strings; {for variables that point into |str_start|}
+@!packed_ASCII_code = 0..255; {elements of |str_pool| array}
+
+@ @<Glob...@>=
+@!str_pool:packed array[pool_pointer] of packed_ASCII_code; {the characters}
+@z
+@x module 42
+begin str_pool[pool_ptr]:=#; incr(pool_ptr);
+@y
+begin str_pool[pool_ptr]:=si(#); incr(pool_ptr);
+@z
+@x module 45
+ begin if str_pool[j]<>buffer[k] then
+@y
+ begin if so(str_pool[j])<>buffer[k] then
+@z
+@x module 47
+var k,@!l:0..127; {small indices or counters}
+@y
+var k,@!l:0..255; {small indices or counters}
+@z
+@x module 47
+@<Make the first 128 strings@>;
+@y
+@<Make the first 256 strings@>;
+@z
+@x module 48
+@ @<Make the first 128...@>=
+for k:=0 to 127 do
+ begin if (@<Character |k| cannot be printed@>) then
+ begin append_char("^"); append_char("^");
+ if k<@'100 then append_char(k+@'100)
+ else append_char(k-@'100);
+@y
+@ @d app_lc_hex(#)==l:=#;
+ if l<10 then append_char(l+"0)@+else append_char(l-10+"a")
+
+@<Make the first 256...@>=
+for k:=0 to 255 do
+ begin if (@<Character |k| cannot be printed@>) then
+ begin append_char("^"); append_char("^");
+ if k<@'100 then append_char(k+@'100)
+ else if k<@'200 then append_char(k-@'100)
+ else begin app_lc_hex(k div 16); app_lc_hex(k mod 16);
+ end;
+@z
+@x module 59
+ begin print_char(str_pool[j]); incr(j);
+@y
+ begin print_char(so(str_pool[j])); incr(j);
+@z
+@x modules 59 and 60
+else if s<128 then
+@y
+else if s<256 then
+@z
+@x module 60
+ begin print(str_pool[j]); incr(j);
+@y
+ begin print(so(str_pool[j])); incr(j);
+@z
+@x module 63
+if c>=0 then if c<128 then print(c);
+@y
+if c>=0 then if c<256 then print(c);
+@z
+@x module 68
+@ In certain situations, \TeX\ prints either a standard visible ASCII
+character or its hexadecimal ASCII code.
+
+@p procedure print_ASCII(@!c:integer); {prints a character or its code}
+begin if (c>=0) and (c<=127) then print(c)
+else begin print_char("[");
+ if c<0 then print_int(c)@+else print_hex(c);
+ print_char("]");
+ end;
+end;
+@y
+@ Old versions of \TeX\ needed a procedure called |print_ASCII| whose function
+is now subsumed by |print|. We retain the old name here as a possible aid to
+future software arch\ae ologists.
+
+@d print_ASCII == print
+@z
+@x module 69
+ begin print_char(str_pool[j]); n:=n-v;
+ end;
+ if n<=0 then return; {nonpositive input produces no output}
+ k:=j+2; u:=v div (str_pool[k-1]-"0");
+ if str_pool[k-1]="2" then
+ begin k:=k+2; u:=u div (str_pool[k-1]-"0");
+ end;
+ if n+u>=v then
+ begin print_char(str_pool[k]); n:=n+u;
+ end
+ else begin j:=j+2; v:=v div (str_pool[j-1]-"0");
+@y
+ begin print_char(so(str_pool[j])); n:=n-v;
+ end;
+ if n<=0 then return; {nonpositive input produces no output}
+ k:=j+2; u:=v div (so(str_pool[k-1])-"0");
+ if str_pool[k-1]=si("2") then
+ begin k:=k+2; u:=u div (so(str_pool[k-1])-"0");
+ end;
+ if n+u>=v then
+ begin print_char(so(str_pool[k])); n:=n+u;
+ end
+ else begin j:=j+2; v:=v div (so(str_pool[j-1])-"0");
+@z
+@x module 70
+ begin print_char(str_pool[j]); incr(j);
+@y
+ begin print_char(so(str_pool[j])); incr(j);
+@z
+@x module 222
+@d single_base=active_base+128 {equivalents of one-letter control sequences}
+@d null_cs=single_base+128 {equivalent of \.{\\csname\\endcsname}}
+@y
+@d single_base=active_base+256 {equivalents of one-character control sequences}
+@d null_cs=single_base+256 {equivalent of \.{\\csname\\endcsname}}
+@z
+@x module 230
+ {table of 128 command codes (the ``catcodes'')}
+@d lc_code_base=cat_code_base+128 {table of 128 lowercase mappings}
+@d uc_code_base=lc_code_base+128 {table of 128 uppercase mappings}
+@d sf_code_base=uc_code_base+128 {table of 128 spacefactor mappings}
+@d math_code_base=sf_code_base+128 {table of 128 math mode mappings}
+@d int_base=math_code_base+128 {beginning of region 5}
+@y
+ {table of 256 command codes (the ``catcodes'')}
+@d lc_code_base=cat_code_base+256 {table of 256 lowercase mappings}
+@d uc_code_base=lc_code_base+256 {table of 256 uppercase mappings}
+@d sf_code_base=uc_code_base+256 {table of 256 spacefactor mappings}
+@d math_code_base=sf_code_base+256 {table of 256 math mode mappings}
+@d int_base=math_code_base+256 {beginning of region 5}
+@z
+@x module 232
+for k:=0 to 127 do
+@y
+for k:=0 to 255 do
+@z
+@x module 236
+@d del_code_base=count_base+256 {128 delimiter code mappings}
+@d dimen_base=del_code_base+128 {beginning of region 6}
+@y
+@d del_code_base=count_base+256 {256 delimiter code mappings}
+@d dimen_base=del_code_base+256 {beginning of region 6}
+@z
+@x module 240
+for k:=0 to 127 do del_code(k):=-1;
+@y
+for k:=0 to 255 do del_code(k):=-1;
+@z
+@x module 264
+begin if s<128 then cur_val:=s+single_base
+@y
+begin if s<256 then cur_val:=s+single_base
+@z
+@x ibid
+ for j:=0 to l-1 do buffer[j]:=str_pool[k+j];
+@y
+ for j:=0 to l-1 do buffer[j]:=so(str_pool[k+j]);
+@z
+@x module 289
+@d cs_token_flag==@'10000 {amount added to the |eqtb| location in a
+ token that stands for a control sequence; is a multiple of~256}
+@y
+@d cs_token_flag==@'7777 {amount added to the |eqtb| location in a
+ token that stands for a control sequence; is a multiple of~256, less~1}
+@z
+@x module 293
+ if (info(p)<0)or(c>127) then print_esc("BAD.")
+@y
+ if info(p)<0 then print_esc("BAD.")
+@z
+@x module 341
+@!cat:0..15; {|cat_code(cur_chr)|, usually}
+@y
+@!cat:0..15; {|cat_code(cur_chr)|, usually}
+@!c,@!cc:ASCII_code; {constituents of a possible expanded code}
+@!d:2..3; {number of excess characters in an expanded code}
+@z
+@x module 352
+@<If this |sup_mark| starts a control character...@>=
+begin if (cur_chr=buffer[loc])and(loc<limit) then
+ begin if buffer[loc+1]<@'100 then cur_chr:=buffer[loc+1]+@'100
+ else cur_chr:=buffer[loc+1]-@'100;
+ loc:=loc+2; goto reswitch;
+ end;
+@y
+@ Notice that a code like \.{\^\^8} becomes \.x if not followed by a hex digit.
+
+@d is_hex(#)==(((#>="0")and(#<="9"))or((#>="a")and(#<="f")))
+@d hex_to_cur_chr==
+ if c<="9" then cur_chr:=c-"0" @+else cur_chr:=c-"a"+10;
+ if cc<="9" then cur_chr:=16*cur_chr+cc-"0"
+ else cur_chr:=16*cur_chr+cc-"a"+10
+
+@<If this |sup_mark| starts an expanded character...@>=
+begin if cur_chr=buffer[loc] then if loc<limit then
+ begin c:=buffer[loc+1]; @+if c<@'200 then {yes we have an expanded char}
+ begin loc:=loc+2;
+ if is_hex(c) then if loc<=limit then
+ begin cc:=buffer[loc]; @+if is_hex(cc) then
+ begin incr(loc); hex_to_cur_chr; goto reswitch;
+ end;
+ end;
+ if c<@'100 then cur_chr:=c+@'100 @+else cur_chr:=c-@'100;
+ goto reswitch;
+ end;
+ end;
+@z
+@x module 355
+ begin cur_chr:=buffer[k+1];
+ if cur_chr<@'100 then buffer[k-1]:=cur_chr+@'100
+ else buffer[k-1]:=cur_chr-@'100;
+ limit:=limit-2; first:=first-2;
+ while k<=limit do
+ begin buffer[k]:=buffer[k+2]; incr(k);
+ end;
+ goto start_cs;
+ end;
+@y
+begin c:=buffer[k+1]; @+if c<@'200 then {yes, one is indeed present}
+ begin d:=2;
+ if is_hex(c) then @+if k+2<=limit then
+ begin cc:=buffer[k+2]; @+if is_hex(cc) then incr(d);
+ end;
+ if d>2 then
+ begin hex_to_cur_chr; buffer[k-1]:=cur_chr;
+ end
+ else if c<@'100 then buffer[k-1]:=c+@'100
+ else buffer[k-1]:=c-@'100;
+ limit:=limit-d; first:=first-d;
+ while k<=limit do
+ begin buffer[k]:=buffer[k+d]; incr(k);
+ end;
+ goto start_cs;
+ end;
+ end;
+@z
+@x module 360
+There is one more branch.
+@y
+There is one more branch.
+
+@d end_line_char_inactive == (end_line_char<0)or(end_line_char>255)
+@z
+@x ibid
+ if (end_line_char<0)or(end_line_char>127) then decr(limit)
+@y
+ if end_line_char_inactive then decr(limit)
+@z
+@x modules 362 and 483 and 538 and 1337
+if (end_line_char<0)or(end_line_char>127) then decr(limit)
+@y
+if end_line_char_inactive then decr(limit)
+@z
+@x module 391
+if (info(r)>match_token+127)or(info(r)<match_token) then s:=null
+@y
+if (info(r)>match_token+255)or(info(r)<match_token) then s:=null
+@z
+@x module 407
+ ((cur_chr=str_pool[k])or(cur_chr=str_pool[k]-"a"+"A")) then
+@y
+ ((cur_chr=so(str_pool[k]))or(cur_chr=so(str_pool[k])-"a"+"A")) then
+@z
+@x module 414
+begin scan_seven_bit_int;
+@y
+begin scan_char_num;
+@z
+@x module 432
+|scan_something_internal|:
+
+@<Declare procedures that scan restricted classes of integers@>=
+procedure scan_seven_bit_int;
+begin scan_int;
+if (cur_val<0)or(cur_val>127) then
+ begin print_err("Bad character code");
+@.Bad character code@>
+ help2("The numeric code for a character must be between 0 and 127.")@/
+ ("I changed this one to zero."); int_error(cur_val); cur_val:=0;
+ end;
+end;
+@y
+|scan_something_internal|.
+@z (and I'll interchange modules 434 and 435)
+@x module 442
+if cur_val>127 then
+@y
+if cur_val>255 then
+@z
+@x module 464
+ begin t:=str_pool[k];
+@y
+ begin t:=so(str_pool[k]);
+@z
+@x module 506 (correction needed twice)
+if (cur_cmd>active_char)or(cur_chr>127) then
+@y
+if (cur_cmd>active_char)or(cur_chr>255) then
+@z
+@x module 519
+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
+for j:=str_start[a] to str_start[a+1]-1 do append_to_name(so(str_pool[j]));
+for j:=str_start[n] to str_start[n+1]-1 do append_to_name(so(str_pool[j]));
+for j:=str_start[e] to str_start[e+1]-1 do append_to_name(so(str_pool[j]));
+@z
+@x module 526
+if (cur_cmd>active_char)or(cur_chr>127) then
+@y
+if (cur_cmd>active_char)or(cur_chr>255) then
+@z
+@x module 603 (change to be made twice)
+ dvi_out(str_pool[k]);
+@y
+ dvi_out(so(str_pool[k]));
+@z
+@x module 617
+ for s:=str_start[str_ptr] to pool_ptr-1 do dvi_out(str_pool[s]);
+@y
+ for s:=str_start[str_ptr] to pool_ptr-1 do dvi_out(so(str_pool[s]));
+@z
+@x module 766
+ begin case str_pool[r_type*8+t+magic_offset] of
+@y
+ begin case so(str_pool[r_type*8+t+magic_offset]) of
+@z
+@x module 780
+@d span_code=128 {distinct from any character}
+@d cr_code=129 {distinct from |span_code| and from any character}
+@y
+@d span_code=256 {distinct from any character}
+@d cr_code=257 {distinct from |span_code| and from any character}
+@z
+@x module 815
+label done,done1,done2,done3,done4;
+@y
+label done,done1,done2,done3,done4,continue;
+@z
+@x module 896
+ else if (type(s)=kern_node)and(subtype(s)=normal) then c:=128
+ else if type(s)=whatsit_node then c:=128
+ else goto done1;
+ if c<128 then if lc_code(c)<>0 then
+ if (lc_code(c)=c)or(uc_hyph>0) then goto done2
+ else goto done1;
+ s:=link(s);
+@y
+ else if (type(s)=kern_node)and(subtype(s)=normal) then goto continue
+ else if type(s)=whatsit_node then goto continue
+ else goto done1;
+ if lc_code(c)<>0 then
+ if (lc_code(c)=c)or(uc_hyph>0) then goto done2
+ else goto done1;
+continue: s:=link(s);
+@z
+@x module 897
+ if c>=128 then goto done3;
+ if (lc_code(c)=0)or(hn=63) then goto done3;
+ hb:=s; incr(hn); hu[hn]:=c; hc[hn]:=lc_code(c)-1;
+@y
+ if lc_code(c)=0 then goto done3;
+ if hn=63 then goto done3;
+ hb:=s; incr(hn); hu[hn]:=c; hc[hn]:=lc_code(c);
+@z
+@x module 898
+if c>=128 then goto done3;
+if (lc_code(c)=0)or(j=63) then goto done3;
+incr(j); hu[j]:=c; hc[j]:=lc_code(c)-1;@/
+@y
+if lc_code(c)=0 then goto done3;
+if j=63 then goto done3;
+incr(j); hu[j]:=c; hc[j]:=lc_code(c);@/
+@z
+@x module 923
+hc[0]:=127; hc[hn+1]:=127; hc[hn+2]:=128; {insert delimiters}
+@y
+hc[0]:=0; hc[hn+1]:=0; hc[hn+2]:=256; {insert delimiters}
+@z
+@x ibid
+ while hc[l]=trie_char(z) do
+@y
+ while hc[l]=qo(trie_char(z)) do
+@z
+@x module 931
+ repeat if str_pool[u]<hc[j] then goto not_found;
+ if str_pool[u]>hc[j] then goto done;
+@y
+ repeat if so(str_pool[u])<hc[j] then goto not_found;
+ if so(str_pool[u])>hc[j] then goto done;
+@z
+@x module 937
+else begin if (cur_chr>127)or(lc_code(cur_chr)=0) then
+@y
+else begin if lc_code(cur_chr)=0 then
+@z
+@x ibid
+ begin incr(n); hc[n]:=lc_code(cur_chr)-1;
+@y
+ begin incr(n); hc[n]:=lc_code(cur_chr);
+@z
+@x module 945
+@!init @!trie_c:packed array[trie_pointer] of ASCII_code; {characters to match}
+@y
+@!init @!trie_c:packed array[trie_pointer] of packed_ASCII_code;
+ {characters to match}
+@z
+% In modules 951--954, change "127" to "255" and "128" to "256"
+@x module 952
+trie_link(0):=0; trie_char(0):=0; trie_op(0):=min_quarterword;
+@y
+trie_link(0):=0; trie_char(0):=min_quarterword; trie_op(0):=min_quarterword;
+@z
+@x module 953
+begin c:=trie_c[p];
+@y
+begin c:=so(trie_c[p]);
+@z
+@x module 955
+ begin if trie_link(h+trie_c[q])=0 then goto not_found;
+@y
+ begin if trie_link(h+so(trie_c[q]))=0 then goto not_found;
+@z
+@x module 956
+repeat z:=h+trie_c[q]; trie_back(trie_link(z)):=trie_back(z);
+@y
+repeat z:=h+so(trie_c[q]); trie_back(trie_link(z)):=trie_back(z);
+@z
+@x module 959
+ begin q:=trie_l[p]; c:=trie_c[p];
+ trie_link(z+c):=trie_ref[q]; trie_char(z+c):=c; trie_op(z+c):=trie_o[p];
+@y
+ begin q:=trie_l[p]; c:=so(trie_c[p]);
+ trie_link(z+c):=trie_ref[q]; trie_char(z+c):=qi(c); trie_op(z+c):=trie_o[p];
+@z
+@x module 962
+ begin if cur_chr="." then cur_chr:=128 {edge-of-word delimiter}
+ else begin cur_chr:=lc_code(cur_chr);
+ if cur_chr=0 then
+ begin print_err("Nonletter");
+@.Nonletter@>
+ help1("(See Appendix H.)"); error; cur_chr:=128;
+ end;
+ end;
+ if k<63 then
+ begin incr(k); hc[k]:=cur_chr-1; hyf[k]:=0; digit_sensed:=false;
+ end;
+ end
+else begin hyf[k]:=cur_chr-"0";
+ if k<63 then digit_sensed:=true;
+ end
+@y
+ begin if cur_chr="." then cur_chr:=0 {edge-of-word delimiter}
+ else begin cur_chr:=lc_code(cur_chr);
+ if cur_chr=0 then
+ begin print_err("Nonletter");
+@.Nonletter@>
+ help1("(See Appendix H.)"); error;
+ end;
+ end;
+ if k<63 then
+ begin incr(k); hc[k]:=cur_chr; hyf[k]:=0; digit_sensed:=false;
+ end;
+ end
+ else if k<63 then
+ begin hyf[k]:=cur_chr-"0"; digit_sensed:=true;
+ end;
+ end
+@z
+@x module 963
+ while (p>0)and(c>trie_c[p]) do
+@y
+ while (p>0)and(c>so(trie_c[p])) do
+@z
+@x ibid
+ if (p=0)or(c<trie_c[p]) then
+@y
+ if (p=0)or(c<so(trie_c[p])) then
+@z
+@x module 964
+trie_c[p]:=c; trie_o[p]:=min_quarterword;
+@y
+trie_c[p]:=si(c); trie_o[p]:=min_quarterword;
+@z
+@x module 965
+if hc[1]=127 then hyf[0]:=0;
+if hc[k]=127 then hyf[k]:=0;
+@y
+if hc[1]=0 then hyf[0]:=0;
+if hc[k]=0 then hyf[k]:=0;
+@z
+@x module 966
+h.rh:=0; h.b0:=min_quarterword; h.b1:=0; {|trie_link:=0|,
+ |trie_op:=min_quarterword|, |trie_char:=0|}
+@y
+h.rh:=0; h.b0:=min_quarterword; h.b1:=min_quarterword; {|trie_link:=0|,
+ |trie_op:=min_quarterword|, |trie_char:=qi(0)|}
+@z
+@x module 1034
+if c<128 then
+@y
+@z
+@x ibid
+else space_factor:=1000
+@y
+@z
+@x module 1151
+letter,other_char,char_given: if cur_chr>=128 then c:=cur_chr
+ else begin c:=ho(math_code(cur_chr));
+@y
+letter,other_char,char_given: begin c:=ho(math_code(cur_chr));
+@z
+@x module 1154
+mmode+letter,mmode+other_char,mmode+char_given: if cur_chr<128 then
+ set_math_char(ho(math_code(cur_chr)))
+ else set_math_char(cur_chr);
+mmode+char_num: begin scan_char_num; cur_chr:=cur_val;
+ if cur_chr<128 then set_math_char(ho(math_code(cur_chr)))
+ else set_math_char(cur_chr);
+@y
+mmode+letter,mmode+other_char,mmode+char_given:
+ set_math_char(ho(math_code(cur_chr)));
+mmode+char_num: begin scan_char_num; cur_chr:=cur_val;
+ set_math_char(ho(math_code(cur_chr)));
+@z
+@x module 1232
+ p:=cur_chr; scan_seven_bit_int; p:=p+cur_val; scan_optional_equals;
+@y
+ p:=cur_chr; scan_char_num; p:=p+cur_val; scan_optional_equals;
+@z
+@x module 1233
+else n:=127
+@y
+else n:=255
+@z
+@x module 1289
+ begin if t>=cs_token_flag then t:=t-active_base;
+ c:=t mod 256;
+ if c<128 then if equiv(b+c)<>0 then t:=256*(t div 256)+equiv(b+c);
+ if t>=cs_token_flag then info(p):=t+active_base
+ else info(p):=t;
+@y
+ begin c:=t mod 256;
+ if equiv(b+c)<>0 then info(p):=t-c+equiv(b+c);
+@z
+@x module 1309
+ w.b0:=str_pool[k]; w.b1:=str_pool[k+1];
+ w.b2:=str_pool[k+2]; w.b3:=str_pool[k+3];
+@y [often qi(so(x))=x, but not e.g. when "quarterwords" are two bytes]
+ w.b0:=qi(so(str_pool[k])); w.b1:=qi(so(str_pool[k+1]));
+ w.b2:=qi(so(str_pool[k+2])); w.b3:=qi(so(str_pool[k+3]));
+@z
+@x module 1310
+ str_pool[k]:=w.b0; str_pool[k+1]:=w.b1;
+ str_pool[k+2]:=w.b2; str_pool[k+3]:=w.b3
+@y
+ str_pool[k]:=si(qo(w.b0)); str_pool[k+1]:=si(qo(w.b1));
+ str_pool[k+2]:=si(qo(w.b2)); str_pool[k+3]:=si(qo(w.b3))
+@z
+@x module 1368
+for k:=str_start[str_ptr] to pool_ptr-1 do dvi_out(str_pool[k]);
+@y
+for k:=str_start[str_ptr] to pool_ptr-1 do dvi_out(so(str_pool[k]));
+@z
+
+360. Major change to allow multiple hyphenation tables.
+I've combined this with the code for a minor change:
+361. New parameters \lefthyphenmin and \righthyphenmin.
+@x module 11 (affects most change files!)
+@!trie_size=8000; {space for hyphenation patterns; should be larger for
+ \.{INITEX} than it is in production versions of \TeX}
+@y
+@!trie_size=8000; {space for hyphenation patterns; should be larger for
+ \.{INITEX} than it is in production versions of \TeX}
+@!trie_op_size=500; {space for ``opcodes'' in the hyphenation patterns}
+@z
+@x module 212
+known as |space_factor|; it holds the current space factor used in spacing
+calculations. In math mode, |aux| is also known as |incompleat_noad|; if
+@y
+known as |space_factor| and |clang|; it holds the current space factor used in
+spacing calculations, and the current language used for hyphenation.
+(The value of |clang| is undefined in restricted horizontal mode.)
+In math mode, |aux| is also known as |incompleat_noad|; if
+@z
+@x ibid
+ @!pg_field,@!aux_field,@!ml_field: integer;
+@y
+ @!pg_field,@!ml_field: integer;
+ @!aux_field: memory_word;
+@z
+@x module 213
+@d prev_depth==aux {the name of |aux| in vertical mode}
+@d space_factor==aux {the name of |aux| in horizontal mode}
+@d incompleat_noad==aux {the name of |aux| in math mode}
+@y
+@d prev_depth==aux.sc {the name of |aux| in vertical mode}
+@d space_factor==aux.hh.lh {part of |aux| in horizontal mode}
+@d clang==aux.hh.rh {the other part of |aux| in horizontal mode}
+@d incompleat_noad==aux.int {the name of |aux| in math mode}
+@z
+@x module 218
+@!a:integer; {auxiliary}
+@y
+@!a:memory_word; {auxiliary}
+@z
+@x module 219
+ if a<=ignore_depth then print("ignored")
+ else print_scaled(a);
+ if nest[p].pg_field<>0 then
+ begin print(", prevgraf ");
+ print_int(nest[p].pg_field); print(" line");
+ if nest[p].pg_field<>1 then print_char("s");
+ end;
+ end;
+1: begin print_nl("spacefactor "); print_int(a);
+ end;
+2: if a<>null then
+ begin print("this will be denominator of:"); show_box(a);
+@y
+ if a.sc<=ignore_depth then print("ignored")
+ else print_scaled(a.sc);
+ if nest[p].pg_field<>0 then
+ begin print(", prevgraf ");
+ print_int(nest[p].pg_field); print(" line");
+ if nest[p].pg_field<>1 then print_char("s");
+ end;
+ end;
+1: begin print_nl("spacefactor "); print_int(a.hh.lh);
+ if m>0 then if a.hh.rh>0 then
+ begin print(", current language "); print_int(a.hh.rh);
+ end;
+ end;
+2: if a.int<>null then
+ begin print("this will be denominator of:"); show_box(a.int);
+@z
+@x modules 236--238
+@d int_pars=50 {total number of integer parameters}
+@y
+@d language_code=50 {current hyphenation table}
+@d left_hyphen_min_code=51 {minimum left hyphenation fragment size}
+@d right_hyphen_min_code=52 {minimum right hyphenation fragment size}
+@d int_pars=53 {total number of integer parameters}
+@z and define/print these new parameters appropriately (mimicking new_line_char)
+@x module 418
+else begin cur_val:=aux;
+ if m=vmode then cur_val_level:=dimen_val@+else cur_val_level:=int_val;
+ end
+@y
+else if m=vmode then
+ begin cur_val:=prev_depth; cur_val_level:=dimen_val;
+ end
+else begin cur_val:=space_factor; cur_val_level:=int_val;
+ end
+@z
+@x module 775
+ begin mode:=-vmode; prev_depth:=nest[nest_ptr-2].aux_field;
+@y
+ begin mode:=-vmode; prev_depth:=nest[nest_ptr-2].aux_field.sc;
+@z
+@x module 786
+begin push_nest; mode:=(-hmode-vmode)-mode; aux:=0;
+@y
+begin push_nest; mode:=(-hmode-vmode)-mode;
+if mode=-hmode then space_factor:=0 @+else prev_depth:=0;
+@z
+@x module 863
+loop@+ begin @<Create an active breakpoint representing the beginning of
+ the paragraph@>;
+@y
+loop@+ begin if threshold>inf_bad then threshold:=inf_bad;
+ if second_pass then @<Initialize for hyphenating a paragraph@>;
+ @<Create an active breakpoint representing the beginning of the paragraph@>;
+@z
+@x module 891
+passes on only about 5 per cent of the paragraphs.
+@y
+passes on only about 5 per cent of the paragraphs.
+
+@<Initialize for hyphenating...@>=
+begin @!init if trie_not_ready then init_trie; @+tini@;@/
+l_hyf:=left_hyphen_min-1;@+if l_hyf<0 then l_hyf:=0;
+r_hyf:=right_hyphen_min-1;@+if r_hyf<0 then r_hyf:=0;
+min_hyf:=l_hyf+r_hyf+2; cur_lang:=0;
+end
+@z
+@x module 892
+@!hyf_char:integer; {hyphen character of the relevant font}
+@y
+@!hyf_char:integer; {hyphen character of the relevant font}
+@!cur_lang:ASCII_code; {current hyphenation table of interest}
+@!l_hyf,@!r_hyf,@!min_hyf:integer; {limits on fragment sizes}
+@z
+@x module 894
+begin s:=link(cur_p);
+@y
+begin if min_hyf>63 then goto done1;
+s:=link(cur_p);
+@z
+@x module 896
+ else if type(s)=whatsit_node then goto continue
+@y
+ else if type(s)=whatsit_node then
+ begin @<Advance \(p)past a whatsit node in the \(p)pre-hyphenation loop@>;
+ goto continue;
+ end
+@z
+@x module 899 (title of this module also changes appropriately)
+if hn<5 then goto done1;
+@y
+if hn<min_hyf then goto done1;
+@z
+@x module 902
+for j:=2 to hn-3 do if odd(hyf[j]) then goto found1;
+@y
+for j:=l_hyf+1 to hn-r_hyf-1 do if odd(hyf[j]) then goto found1;
+@z
+@x module 920
+$p_1\ldots p_k$ by setting |@t$z_1$@>:=@t$p_1$@>| and then, for |1<i<=k|,
+@y
+$p_1\ldots p_k$ by letting $z_0$ be one greater than the relevant language index
+and then, for |1<=i<=k|,
+@z
+@x ibid
+the letters in |hc[(l-k+1)..l@,]|, we perform all of the required operations
+for this pattern by carrying out the following little program: Set
+|v:=trie_op(@t$z_k$@>)|. Then set |hyf[l-hyf_distance[v]]:=@tmax@>(
+hyf[l-hyf_distance[v]], hyf_num[v])|, and |v:=hyf_next[v]|; repeat, if
+necessary, until |v=min_quarterword|.
+@y
+the letters in |hc[(l-k+1)..l@,]| of language |t|,
+we perform all of the required operations
+for this pattern by carrying out the following little program: Set
+|v:=trie_op(@t$z_k$@>)|. Then set |v:=v+op_start[t]|,
+|hyf[l-hyf_distance[v]]:=@tmax@>(hyf[l-hyf_distance[v]], hyf_num[v])|,
+and |v:=hyf_next[v]|; repeat, if necessary, until |v=min_quarterword|.
+@z
+@x module 921
+@!hyf_distance:array[quarterword] of small_number; {position |k-j| of $n_j$}
+@!hyf_num:array[quarterword] of small_number; {value of $n_j$}
+@!hyf_next:array[quarterword] of quarterword; {continuation of this |trie_op|}
+@y
+@!hyf_distance:array[1..trie_op_size] of small_number; {position |k-j| of $n_j$}
+@!hyf_num:array[1..trie_op_size] of small_number; {value of $n_j$}
+@!hyf_next:array[1..trie_op_size] of quarterword; {continuation code}
+@!op_start:array[ASCII_code] of 0..trie_op_size; {offset for current language}
+@z
+@x module 922
+@!v:quarterword; {an index into |hyf_distance|, etc.}
+@y
+@!v:integer; {an index into |hyf_distance|, etc.}
+@z
+@x module 923
+for j:=0 to hn-2 do
+ begin z:=hc[j]; l:=j;
+@y
+if trie_char(cur_lang+1)<>qi(cur_lang) then return; {no patterns for |cur_lang|}
+for j:=0 to hn-r_hyf do
+ begin z:=trie_link(cur_lang+1)+hc[j]; l:=j;
+@z
+@x ibid
+found: hyf[1]:=0; hyf[hn-2]:=0; hyf[hn-1]:=0; hyf[hn]:=0
+@y
+found: for j:=0 to l_hyf do hyf[j]:=0;
+for j:=0 to r_hyf do hyf[hn-j]:=0
+@z
+@x module 924
+repeat i:=l-hyf_distance[v];
+@y
+repeat v:=v+op_start[cur_lang]; i:=l-hyf_distance[v];
+@z
+@x module 930
+h:=hc[1];
+@y
+h:=hc[1]; incr(hn); hc[hn]:=cur_lang;
+@z
+@x ibid
+not_found:
+@y
+not_found: decr(hn)
+@z
+@x module 931
+ goto found;
+@y
+ decr(hn); goto found;
+@z
+@x module 934
+@p procedure new_hyph_exceptions; {enters new exceptions}
+label reswitch, exit, found, not_found, done;
+@y
+@d set_cur_lang==if language<=0 then cur_lang:=0
+ else if language>255 then cur_lang:=0
+ else cur_lang:=language
+
+@p procedure new_hyph_exceptions; {enters new exceptions}
+label reswitch, exit, found, not_found;
+@z
+@x ibid
+begin scan_left_brace; {a left brace must follow \.{\\hyphenation}}
+@y
+begin scan_left_brace; {a left brace must follow \.{\\hyphenation}}
+set_cur_lang;
+@z
+@x module 935
+ spacer,right_brace: begin if n>4 then @<Enter a hyphenation exception@>;
+@y
+ spacer,right_brace: begin if n>1 then @<Enter a hyphenation exception@>;
+@z
+@x module 938
+begin if n>1 then
+@y
+begin if n<63 then
+@z
+@x module 939
+begin str_room(n); h:=0;
+@y
+begin incr(n); hc[n]:=cur_lang; str_room(n); h:=0;
+@z
+@x ibid
+loop@+ begin if p=null then goto done;
+ if info(p)<n-2 then goto done;
+ q:=link(p); free_avail(p); p:=q; {eliminate hyphens that \TeX\ doesn't like}
+ end;
+done: @<Insert the \(p)pair |(s,p)| into the exception table@>;
+@y
+@<Insert the \(p)pair |(s,p)| into the exception table@>;
+@z
+@x module 942
+@p@!init @<Declare procedures for preprocessing hyphenation patterns@>@;
+@y
+@<Declare subprocedures for |line_break|@>=
+@!init @<Declare procedures for preprocessing hyphenation patterns@>@;
+@z
+@x module 943
+@d quarterword_diff=max_quarterword-min_quarterword
+@d trie_op_hash_size=quarterword_diff+quarterword_diff {double}
+
+@<Glob...@>=
+@!init@! trie_op_hash:array[0..trie_op_hash_size] of quarterword;
+ {trie op codes for triples}
+tini@;@/
+@t\hskip1em@>@!trie_op_ptr:quarterword; {highest |trie_op| assigned}
+@y
+@<Glob...@>=
+@!init@! trie_op_hash:array[-trie_op_size..trie_op_size] of 0..trie_op_size;
+ {trie op codes for quadruples}
+@!trie_used:array[ASCII_code] of quarterword;
+ {largest opcode used so far for this language}
+@!trie_op_lang:array[1..trie_op_size] of ASCII_code;
+ {language part of a hashed quadruple}
+@!trie_op_val:array[1..trie_op_size] of quarterword;
+ {opcode corresponding to a hashed quadruple}
+@!trie_op_ptr:0..trie_op_size; {number of stored ops so far}
+tini
+@z
+@x module 944 should be entirely replaced
+@y by the following code:
+@ It's tempting to remove the |overflow| stops in the following procedure;
+|new_trie_op| could return |min_quarterword| (thereby simply ignoring
+part of a hyphenation pattern) instead of aborting the job. However, that would
+lead to different hyphenation results on different installations of \TeX\
+using the same patterns. The |overflow| stops are necessary for portability
+of patterns.
+
+@<Declare procedures for preprocessing hyph...@>=
+function new_trie_op(@!d,@!n:small_number;@!v:quarterword):quarterword;
+label exit;
+var h:-trie_op_size..trie_op_size; {trial hash location}
+@!u:quarterword; {trial op code}
+@!l:0..trie_op_size; {pointer to stored data}
+begin h:=abs(n+313*d+361*v+1009*cur_lang) mod (trie_op_size+trie_op_size)
+ - trie_op_size;
+loop@+ begin l:=trie_op_hash[h];
+ if l=0 then {empty position found for a new op}
+ begin if trie_op_ptr=trie_op_size then
+ overflow("pattern memory ops",trie_op_size);
+ u:=trie_used[cur_lang];
+ if u=max_quarterword then
+ overflow("pattern memory ops per language",
+ max_quarterword-min_quarterword);
+ incr(trie_op_ptr); incr(u); trie_used[cur_lang]:=u;
+ hyf_distance[trie_op_ptr]:=d;
+ hyf_num[trie_op_ptr]:=n; hyf_next[trie_op_ptr]:=v;
+ trie_op_lang[trie_op_ptr]:=cur_lang; trie_op_hash[h]:=trie_op_ptr;
+ trie_op_val[trie_op_ptr]:=u; new_trie_op:=u; return;
+ end;
+ if (hyf_distance[l]=d)and(hyf_num[l]=n)and(hyf_next[l]=v)
+ and(trie_op_lang[l]=cur_lang) then
+ begin new_trie_op:=trie_op_val[l]; return;
+ end;
+ if h>-trie_op_size then decr(h)@+else h:=trie_op_size;
+ end;
+exit:end;
+@z
+@x module 945: move the code from this module into 946, and introduce new code:
+@y
+@ After |new_trie_op| has compressed the necessary opcode information,
+plenty of information is available to unscramble the data into the
+final form needed by our hyphenation algorithm.
+
+@<Sort the hyphenation op tables into proper order@>=
+op_start[0]:=-min_quarterword;
+for j:=1 to 255 do op_start[j]:=op_start[j-1]+qo(trie_used[j-1]);
+for j:=1 to trie_op_ptr do
+ trie_op_hash[j]:=op_start[trie_op_lang[j]]+trie_op_val[j]; {destination}
+for j:=1 to trie_op_ptr do while trie_op_hash[j]>j do
+ begin k:=trie_op_hash[j];@/
+ t:=hyf_distance[k]; hyf_distance[k]:=hyf_distance[j]; hyf_distance[j]:=t;@/
+ t:=hyf_num[k]; hyf_num[k]:=hyf_num[j]; hyf_num[j]:=t;@/
+ t:=hyf_next[k]; hyf_next[k]:=hyf_next[j]; hyf_next[j]:=t;@/
+ trie_op_hash[j]:=trie_op_hash[k]; trie_op_hash[k]:=k;
+ end
+@z
+@x module 949: Move this code to just after the new module 945!
+mentioned so far, let's write a procedure that does the initialization.
+
+@<Declare procedures for preprocessing hyph...@>=
+procedure init_pattern_memory; {gets ready to build a linked trie}
+var h:0..trie_op_hash_size; {an index into |trie_op_hash|}
+@!p:trie_pointer; {an index into |trie_hash|}
+begin for h:=0 to trie_op_hash_size do trie_op_hash[h]:=min_quarterword;
+trie_op_ptr:=min_quarterword; trie_root:=0; trie_c[0]:=0; trie_ptr:=0;
+for p:=0 to trie_size do trie_hash[p]:=0;
+end;
+@y
+mentioned so far, let's write down the code that gets them started.
+
+@<Initialize table entries...@>=
+for k:=-trie_op_size to trie_op_size do trie_op_hash[k]:=0;
+for k:=0 to 255 do trie_used[k]:=min_quarterword;
+trie_op_ptr:=0;
+@z
+@x module 950
+@t\hskip1em@>@!trie_min:trie_pointer;
+ {all locations |<=trie_min| are vacant in |trie|}
+tini@;@/
+@t\hskip1em@>@!trie_max:trie_pointer; {largest location used in |trie|}
+@y
+@t\hskip10pt@>@!trie_min:array[ASCII_code] of trie_pointer;
+ {the first possible slot for each character}
+@t\hskip10pt@>@!trie_max:trie_pointer; {largest location used in |trie|}
+@t\hskip10pt@>@!trie_not_ready:boolean; {is the trie still in linked form?}
+tini
+@z
+@x modules 951 and 952
+@ Here is how these data structures are initialized.
+
+@<Declare procedures for preprocessing hyph...@>=
+procedure init_trie_memory; {gets ready to pack into |trie|}
+var p:trie_pointer; {index into |trie_ref|, |trie|, |trie_taken|}
+begin for p:=0 to trie_ptr do trie_ref[p]:=0;
+trie_max:=256; trie_min:=256; trie_link(0):=1; trie_taken[0]:=false;
+trie_link(trie_size):=0; trie_back(0):=trie_size; {wrap around}
+for p:=1 to 256 do
+ begin trie_back(p):=p-1; trie_link(p):=p+1; trie_taken[p]:=false;
+ end;
+end;
+
+@ Each time \.{\\patterns} appears, it overrides any patterns that were
+entered earlier, so the arrays are not initialized until \TeX\ sees
+\.{\\patterns}. However, some of the global variables must be
+initialized when \.{INITEX} is loaded, in case the user never mentions
+any \.{\\patterns}.
+
+@<Initialize table entries...@>=
+trie_op_ptr:=min_quarterword;@/
+trie_link(0):=0; trie_char(0):=min_quarterword; trie_op(0):=min_quarterword;
+for k:=1 to 255 do trie[k]:=trie[0];
+trie_max:=255;
+@y
+@ Each time \.{\\patterns} appears, it contributes further patterns to
+the future trie, which will be built only when hyphenation is attempted or
+when a format file is dumped. The boolean variable |trie_not_ready|
+will change to |false| when the trie is compressed; this will disable
+further patterns.
+
+@<Initialize table entries...@>=
+trie_not_ready:=true; trie_root:=0; trie_c[0]:=si(0); trie_ptr:=0;
+
+@ Here is how the trie-compression data structures are initialized.
+If storage is tight, it would be possible to overlap |trie_op_hash|,
+|trie_op_lang|, and |trie_op_val| with |trie|, |trie_hash|, and |trie_taken|,
+because we finish with the former just before we need the latter.
+
+@<Get ready to compress the trie@>=
+@<Sort the hyphenation...@>;
+for p:=0 to trie_size do trie_hash[p]:=0;
+trie_root:=compress_trie(trie_root); {identify equivalent subtries}
+for p:=0 to trie_ptr do trie_ref[p]:=0;
+for p:=0 to 255 do trie_min[p]:=p+1;
+trie_link(0):=1; trie_max:=0
+@z
+@x module 953
+begin c:=so(trie_c[p]);
+if c<trie_min then trie_min:=c;
+if trie_min=0 then z:=trie_link(trie_size)
+else z:=trie_link(trie_min-1); {get the first conceivably good hole}
+loop@+ begin if z<c then goto not_found;
+ h:=z-c;@/
+@y
+@!l,@!r:trie_pointer; {left and right neighbors}
+@!ll:1..256; {upper limit of |trie_min| updating}
+begin c:=so(trie_c[p]);
+z:=trie_min[c]; {get the first conceivably good hole}
+loop@+ begin h:=z-c;@/
+@z
+@x module 956
+repeat z:=h+so(trie_c[q]); trie_back(trie_link(z)):=trie_back(z);
+trie_link(trie_back(z)):=trie_link(z); trie_link(z):=0; q:=trie_r[q];
+@y
+repeat z:=h+so(trie_c[q]); l:=trie_back(z); r:=trie_link(z);
+trie_back(r):=l; trie_link(l):=r; trie_link(z):=0;
+if l<256 then
+ begin if z<256 then ll:=z @+else ll:=256;
+ repeat trie_min[l]:=r; incr(l);
+ until l=ll;
+ end;
+q:=trie_r[q];
+@z
+@x module 958 is entirely replaced
+@y by the following new code:
+@ When the whole trie has been allocated into the sequential table, we
+must go through it once again so that |trie| contains the correct
+information. Null pointers in the linked trie will be represented by the
+value~0, which properly implements an ``empty'' family.
+
+@<Move the data into |trie|@>=
+h.rh:=0; h.b0:=min_quarterword; h.b1:=min_quarterword; {|trie_link:=0|,
+ |trie_op:=min_quarterword|, |trie_char:=qi(0)|}
+if trie_root=0 then {no patterns were given}
+ begin for r:=0 to 256 do trie[r]:=h;
+ trie_max:=256;
+ end
+else begin trie_fix(trie_root); {this fixes the non-holes in |trie|}
+ r:=0; {now we will zero out all the holes}
+ repeat s:=trie_link(r); trie[r]:=h; r:=s;
+ until r>trie_max;
+ end;
+trie_char(0):=qi("?"); {make |trie_char(c)<>c| for all |c|}
+@z
+@x module 960
+@!r,@!s:trie_pointer; {used to clean up the packed |trie|}
+@!h:two_halves; {template used to zero out |trie|'s holes}
+begin scan_left_brace; {a left brace must follow \.{\\patterns}}
+init_pattern_memory;@/
+@<Enter all of the patterns into a linked trie, until coming to a right
+ brace@>;
+trie_root:=compress_trie(trie_root); {compress the trie}
+@<Pack the trie@>;
+end;
+@y
+begin if trie_not_ready then
+ begin set_cur_lang; scan_left_brace; {a left brace must follow \.{\\patterns}}
+ @<Enter all of the patterns into a linked trie, until coming to a right
+ brace@>;
+ end
+else begin print_err("Too late for "); print_esc("patterns");
+ help1("All patterns must be given before typesetting begins.");
+ error; link(garbage):=scan_toks(false,false); flush_list(def_ref);
+ end;
+end;
+@z
+@x module 963
+q:=0;
+while l<k do
+ begin incr(l); c:=hc[l]; p:=trie_l[q]; first_child:=true;
+@y
+q:=0; hc[0]:=cur_lang;
+while l<=k do
+ begin c:=hc[l]; incr(l); p:=trie_l[q]; first_child:=true;
+@z
+@x module 966 now says that the first call ``takes'' location 1,
+@y and the Pascal code in this module is entirely replaced by the following:
+@<Declare procedures for preprocessing hyphenation patterns@>=
+procedure init_trie;
+var @!p:trie_pointer; {pointer for initialization}
+@!j,@!k,@!t:integer; {all-purpose registers for initialization}
+@!r,@!s:trie_pointer; {used to clean up the packed |trie|}
+@!h:two_halves; {template used to zero out |trie|'s holes}
+begin @<Get ready to compress the trie@>;
+if trie_root<>0 then
+ begin first_fit(trie_root); trie_pack(trie_root);
+ end;
+@<Move the data into |trie|@>;
+trie_not_ready:=false;
+end;
+@z
+@x module 1033 gets new code before main_loop_1
+@y
+if mode>0 then if language<>clang then fix_language;
+@z
+@x modules 1091 and 1200
+push_nest; mode:=hmode; space_factor:=1000;
+@y
+push_nest; mode:=hmode; space_factor:=1000; clang:=0;
+@z
+@x module 1324
+for k:=0 to trie_max do dump_hh(trie[k]);
+dump_int(trie_op_ptr);
+for k:=min_quarterword+1 to trie_op_ptr do
+ begin dump_int(hyf_distance[k]);
+ dump_int(hyf_num[k]);
+ dump_int(hyf_next[k]);
+ end;
+print_ln; print_int(hyph_count); print(" hyphenation exception");
+if hyph_count<>1 then print_char("s");
+print_nl("Hyphenation trie of length "); print_int(trie_max);
+@.Hyphenation trie...@>
+print(" has "); print_int(qo(trie_op_ptr)); print(" op");
+if trie_op_ptr<>min_quarterword+1 then print_char("s")
+@y
+print_ln; print_int(hyph_count); print(" hyphenation exception");
+if hyph_count<>1 then print_char("s");
+if trie_not_ready then init_trie;
+dump_int(trie_max);
+for k:=0 to trie_max do dump_hh(trie[k]);
+dump_int(trie_op_ptr);
+for k:=1 to trie_op_ptr do
+ begin dump_int(hyf_distance[k]);
+ dump_int(hyf_num[k]);
+ dump_int(hyf_next[k]);
+ end;
+print_nl("Hyphenation trie of length "); print_int(trie_max);
+@.Hyphenation trie...@>
+print(" has "); print_int(trie_op_ptr); print(" op");
+if trie_op_ptr<>1 then print_char("s");
+print(" out of "); print_int(trie_op_size);
+for k:=255 downto 0 do if trie_used[k]>min_quarterword then
+ begin print_nl(" "); print_int(qo(trie_used[k]));
+ print(" for language "); print_int(k);
+ dump_int(k); dump_int(qo(trie_used[k]));
+ end
+@z
+@x module 1325
+undump_size(0)(trie_size)('trie size')(trie_max);
+for k:=0 to trie_max do undump_hh(trie[k]);
+undump(min_quarterword)(max_quarterword)(trie_op_ptr);
+for k:=min_quarterword+1 to trie_op_ptr do
+ begin undump(0)(63)(hyf_distance[k]); {a |small_number|}
+ undump(0)(63)(hyf_num[k]);
+ undump(min_quarterword)(max_quarterword)(hyf_next[k]);
+ end
+@y
+undump_size(0)(trie_size)('trie size')(j); {|trie_max|}
+for k:=0 to j do undump_hh(trie[k]);
+undump_size(0)(trie_op_size)('trie op size')(j); {|trie_op_ptr|}
+for k:=1 to j do
+ begin undump(0)(63)(hyf_distance[k]); {a |small_number|}
+ undump(0)(63)(hyf_num[k]);
+ undump(min_quarterword)(max_quarterword)(hyf_next[k]);
+ end;
+k:=256;
+while j>0 do
+ begin undump(0)(k-1)(k); undump(1)(j)(x); j:=j-x; op_start[k]:=qo(j);
+ end;
+@!init trie_not_ready:=false @+tini
+@z
+@x module 1341 gets two new definitions
+@y
+@d language_node=4 {|subtype| in whatsits that change the current language}
+@d stored_language(#)==mem[#+1].int {language number, in the range |0..255|}
+@z
+@x module 1344 gets a new definition and a new Pascal statement
+@y
+@d set_language_code=5 {command modifier for \.{\\setlanguage}}
+primitive("setlanguage",extension,set_language_code);@/
+@!@:set_language_}{\.{\\setlanguage} primitive@>
+@z
+@x module 1346 gets a new case
+@y
+ set_language_code:print_esc("setlanguage");
+@z
+@x module 1348 gets a new case
+@y
+set_language_code:@<Implement \.{\\setlanguage}@>;
+@z
+@x module 1356 gets a new case
+@y
+language_node:begin print_esc("setlanguage");
+ print_int(stored_language(p));
+ end;
+@z
+% in modules 1357 and 1358, change "close_node" to "close_node,language_node".
+@x module 1362 becomes two modules
+@ @<Advance \(p)past a whatsit node in the |line_break| loop@>=do_nothing
+@y
+@ @<Advance \(p)past a whatsit node in the \(l)|line_break| loop@>=
+if subtype(cur_p)=language_node then cur_lang:=stored_language(cur_p)
+
+@ @<Advance \(p)past a whatsit node in the \(p)pre-hyphenation loop@>=
+if subtype(s)=language_node then cur_lang:=stored_language(s)
+@z and old module 1367 is moved to just before the old module 1378
+@x module 1373 gets a new case
+@y
+language_node:do_nothing;
+@z
+@x new modules before the system-dependent changes (i.e. before the old 1376)
+@y
+@ @<Implement \.{\\setlanguage}@>=
+if abs(mode)<>hmode then report_illegal_case
+else begin new_whatsit(language_node,small_node_size);
+ scan_int;
+ if cur_val<=0 then clang:=0
+ else if cur_val>255 then clang:=0
+ else clang:=cur_val;
+ stored_language(tail):=clang;
+ end
+
+@ Finally, we need a subroutine that comes into play when a character of
+a non-|clang| language is being appended to the current paragraph.
+
+@<Declare action...@>=
+procedure fix_language;
+var @!l:ASCII_code; {the new current language}
+begin if language<=0 then l:=0
+else if language>255 then l:=0
+else l:=language;
+if l<>clang then
+ begin new_whatsit(language_node,small_node_size);
+ stored_language(tail):=l; clang:=l;
+ end;
+end;
+@z
+
+362. Major extension to ligature capability.
+@x module 143
+a linked list of character nodes for those characters.
+@y
+a linked list of character nodes for all original characters that have been
+deleted. (This list might be empty if the characters that generated the
+ligature were retained in other nodes.)
+
+The |subtype| field is 0, plus 2 and/or 1 if the original source of the
+ligature included implicit left and/or right boundaries.
+@z
+@x in module 144 add the following procedure to the existing code
+@y
+function new_lig_item(@!c:quarterword):pointer;
+var p:pointer; {the new node}
+begin p:=get_node(small_node_size); character(p):=c; lig_ptr(p):=null;
+new_lig_item:=p;
+end;
+@z
+@x module 193
+font_in_short_display:=font(lig_char(p));
+short_display(lig_ptr(p)); print_char(")");
+@y
+if subtype(p)>1 then print_char("|");
+font_in_short_display:=font(lig_char(p)); short_display(lig_ptr(p));
+if odd(subtype(p)) then print_char("|");
+print_char(")");
+end
+@z
+@x modules 208 and 209
+@d radical=65 {square root and similar signs ( \.{\\radical} )}
+@y
+@d no_boundary=65 {suppress boundary ligatures ( \.{\\noboundary} )}
+@d radical=66 {square root and similar signs ( \.{\\radical} )}
+@z and so on, adding 1 to each definition until getting to max_command=100
+@x module 265 gets a new statement
+@y
+primitive("noboundary",no_boundary,0);@/
+@!@:no_boundary_}{\.{\\noboundary} primitive@>
+@z
+@x module 266 gets a new case
+@y
+no_boundary:print_esc("noboundary");
+@z
+@x module 545 is entirely replaced
+@y by the following new specifications:
+@ The |lig_kern| array contains instructions in a simple programming language
+that explains what to do for special letter pairs. Each word in this array is a
+|@!lig_kern_command| of four bytes.
+
+\yskip\hang first byte: |skip_byte|, indicates that this is the final program
+ step if the byte is 128 or more, otherwise the next step is obtained by
+ skipping this number of intervening steps.\par
+\hang second byte: |next_char|, ``if |next_char| follows the current character,
+ then perform the operation and stop, otherwise continue.''\par
+\hang third byte: |op_byte|, indicates a ligature step if less than~128,
+ a kern step otherwise.\par
+\hang fourth byte: |remainder|.\par
+\yskip\noindent
+In a kern step, an
+additional space equal to |kern[256*(op_byte-128)+remainder]| is inserted
+between the current character and |next_char|. This amount is
+often negative, so that the characters are brought closer together
+by kerning; but it might be positive.
+
+There are eight kinds of ligature steps, having |op_byte| codes $4a+2b+c$ where
+$0\le a\le b+c$ and $0\le b,c\le1$. The character whose code is
+|remainder| is inserted between the current character and |next_char|;
+then the current character is deleted if $b=0$, and |next_char| is
+deleted if $c=0$; then we pass over $a$~characters to reach the next
+current character (which may have a ligature/kerning program of its own).
+
+If the very first instruction of the |lig_kern| array has |skip_byte=255|,
+the |next_char| byte is the so-called right boundary character of this font;
+the value of |next_char| need not lie between |bc| and~|ec|.
+If the very last instruction of the |lig_kern| array has |skip_byte=255|,
+there is a special ligature/kerning program for a left boundary character,
+beginning at location |256*op_byte+remainder|.
+The interpretation is that \TeX\ puts implicit boundary characters
+before and after each consecutive string of characters from the same font.
+These implicit characters do not appear in the output, but they can affect
+ligatures and kerning.
+
+If the very first instruction of a character's |lig_kern| program has
+|skip_byte>128|, the program actually begins in location
+|256*op_byte+remainder|. This feature allows access to large |lig_kern|
+arrays, because the first instruction must otherwise
+appear in a location |<=255|.
+
+Any instruction with |skip_byte>128| in the |lig_kern| array must have
+|256*op_byte+remainder<nl|. If such an instruction is encountered during
+normal program execution, it denotes an unconditional halt; no ligature
+command is performed.
+
+@d stop_flag=qi(128) {value indicating `\.{STOP}' in a lig/kern program}
+@d kern_flag=qi(128) {op code for a kern step}
+@d skip_byte(#)==#.b0
+@d next_char(#)==#.b1
+@d op_byte(#)==#.b2
+@d rem_byte(#)==#.b3
+@z
+@x module 549
+@<Glob...@>=
+@y
+@d non_char==qi(256) {a |halfword| code that can't match a real character}
+@d non_address==font_mem_size {a spurious |font_index|}
+
+@<Glob...@>=
+@z
+@x module 548 gets a new type definition
+@y
+@!font_index=0..font_mem_size;
+@z
+@x module 549
+ {current \.{\\skewchar} values}
+@y
+ {current \.{\\skewchar} values}
+@!bchar_label:array[internal_font_number] of font_index;
+ {start of |lig_kern| program for left boundary character,
+ |non_address| if there is none}
+@!font_bchar:array[internal_font_number] of min_quarterword..non_char;
+ {right boundary character, |non_char| if there is none}
+@!font_false_bchar:array[internal_font_number] of min_quarterword..non_char;
+ {|font_bchar| if it doesn't exist in the font, otherwise |non_char|}
+@z
+@x module 557
+@d char_kern_end(#)==rem_byte(#)].sc
+@y NOTE: Optimize kern_base_offset in your change file! It's a constant.
+@d char_kern_end(#)==256*op_byte(#)+rem_byte(#)].sc
+@d kern_base_offset==256*(kern_flag)
+@d lig_kern_restart_end(#)==256*op_byte(#)+rem_byte(#)+32768-kern_base_offset
+@d lig_kern_restart(#)==lig_kern_base[#]+lig_kern_restart_end
+@z
+@x module 560
+@!z:scaled; {the design size or the ``at'' size}
+@y
+@!bch_label:integer; {left boundary start location, or infinity}
+@!bchar:0..256; {right boundary character, or 256}
+@!z:scaled; {the design size or the ``at'' size}
+@z
+@x module 566
+kern_base[f]:=lig_kern_base[f]+nl;
+exten_base[f]:=kern_base[f]+nk;
+@y
+kern_base[f]:=lig_kern_base[f]+nl-kern_base_offset;
+exten_base[f]:=kern_base[f]+kern_base_offset+nk;
+@z
+@x module 573: The entire module is replaced
+@y by the following code.
+@ @d check_existence(#)==@t@>@;@/
+ begin check_byte_range(#);
+ qw:=char_info(f)(#); {N.B.: not |qi(#)|}
+ if not char_exists(qw) then abort;
+ end
+
+@<Read ligature/kern program@>=
+bch_label:=@'77777; bchar:=256;
+if nl>0 then
+ begin for k:=lig_kern_base[f] to kern_base[f]+kern_base_offset-1 do
+ begin store_four_quarters(font_info[k].qqqq);
+ if a>128 then
+ begin if 256*c+d>=nl then abort;
+ if a=255 then if k=lig_kern_base[f] then bchar:=b;
+ end
+ else begin if b<>bchar then check_existence(b);
+ if c<128 then check_existence(d) {check ligature}
+ else if 256*(c-128)+d>=nk then abort; {check kern}
+ if a<128 then if k-lig_kern_base[f]+a+1>=nl then abort;
+ end;
+ end;
+ if a=255 then bch_label:=256*c+d;
+ end;
+for k:=kern_base[f]+kern_base_offset to exten_base[f]-1 do
+ store_scaled(font_info[k].sc);
+@z
+@x module 574 (actually a bugfix)
+ if a<>0 then check_byte_range(a);
+ if b<>0 then check_byte_range(b);
+ if c<>0 then check_byte_range(c);
+ check_byte_range(d);
+@y
+ if a<>0 then check_existence(a);
+ if b<>0 then check_existence(b);
+ if c<>0 then check_existence(c);
+ check_existence(d);
+@z
+@x module 576
+font_name[f]:=nom;
+@y
+if bch_label<nl then bchar_label[f]:=bch_label+lig_kern_base[f]
+else bchar_label[f]:=non_address;
+font_bchar[f]:=qi(bchar);
+font_false_bchar[f]:=qi(bchar);
+if bchar<=ec then if bchar>=bc then
+ begin qw:=char_info(f)(bchar); {N.B.: not |qi(bchar)|}
+ if char_exists(qw) then font_false_bchar[f]:=non_char;
+ end;
+font_name[f]:=nom;
+@z
+@x module 708 (slight but optional optimization)
+continue: if (qo(y)>=font_bc[g])and(qo(y)<=font_ec[g]) then
+ begin q:=char_info(g)(y);
+@y
+if (qo(y)>=font_bc[g])and(qo(y)<=font_ec[g]) then
+ begin continue: q:=char_info(g)(y);
+@z
+@x module 740 (another bugfix)
+ i:=char_info(f)(y);
+@y
+ i:=char_info(f)(y);
+ if not char_exists(i) then goto done;
+@z
+@x module 741
+ repeat cur_i:=font_info[a].qqqq;
+ if qo(next_char(cur_i))=skew_char[cur_f] then
+ begin if op_bit(cur_i)>=kern_flag then
+ s:=char_kern(cur_f)(cur_i);
+ goto done1;
+ end;
+ incr(a);
+ until stop_bit(cur_i)>=stop_flag;
+@y
+ cur_i:=font_info[a].qqqq;
+ if skip_byte(cur_i)>stop_flag then
+ begin a:=256*(qo(op_byte(cur_i)))+rem_byte(cur_i);
+ cur_i:=font_info[a].qqqq;
+ end;
+ loop begin if qo(next_char(cur_i))=skew_char[cur_f] then
+ begin if op_byte(cur_i)>=kern_flag then
+ if skip_byte(cur_i)<=stop_flag then s:=char_kern(cur_f)(cur_i);
+ goto done1;
+ end;
+ if skip_byte(cur_i)>=stop_flag then goto done1
+ else a:=a+qo(skip_byte(cur_i))+1;
+ cur_i:=font_info[a].qqqq;
+ end;
+@z
+@x module 749 (yet another bugfix of the same type!)
+@!p,@!v,@!x,@!y,@!z:pointer; {temporary registers for box construction}
+@y
+@!p,@!v,@!x,@!y,@!z:pointer; {temporary registers for box construction}
+@!c:quarterword;@+@!i:four_quarters; {registers for character examination}
+@z
+@x ibid
+ begin cur_c:=rem_byte(cur_i); character(nucleus(q)):=cur_c;
+ cur_i:=char_info(cur_f)(cur_c);
+@y
+ begin c:=rem_byte(cur_i); i:=char_info(cur_f)(c);
+ if char_exists(i) then
+ begin cur_c:=c; cur_i:=i; character(nucleus(q)):=c;
+ end;
+@z
+@x module 752
+@!p:pointer; {temporary register for list manipulation}
+@y
+@!p,@!r:pointer; {temporary registers for list manipulation}
+@z
+@x ibid
+ repeat cur_i:=font_info[a].qqqq;@/
+ @<If instruction |cur_i| is a kern with |cur_c|,
+ attach the kern after |q| and |return|;
+ or if it is a ligature with |cur_c|, combine
+ noads |q| and |p| and |goto restart|@>;
+ incr(a);
+ until stop_bit(cur_i)>=stop_flag;
+@y
+ cur_i:=font_info[a].qqqq;
+ if skip_byte(cur_i)>stop_flag then
+ begin a:=lig_kern_restart(cur_f)(cur_i);
+ cur_i:=font_info[a].qqqq;
+ end;
+ loop@+ begin @<If instruction |cur_i| is a kern with |cur_c|, attach
+ the kern after~|q|; or if it is a ligature with |cur_c|, combine
+ noads |q| and~|p| appropriately; then |return| if the cursor has
+ moved past a noad, or |goto restart|@>;
+ if skip_byte(cur_i)>=stop_flag then return;
+ a:=a+qo(skip_byte(cur_i))+1;
+ cur_i:=font_info[a].qqqq;
+ end;
+@z
+@x The entire code of module 753 is revised
+@y and should be replaced by the following:
+@ Note that a ligature between an |ord_noad| and another kind of noad
+is replaced by an |ord_noad|, when the two noads collapse into one.
+But we could make a parenthesis (say) change shape when it follows
+certain letters. Presumably a font designer will define such
+ligatures only when this convention makes sense.
+
+\chardef\?='174 % vertical line to indicate character retention
+
+@<If instruction |cur_i| is a kern with |cur_c|, ...@>=
+if next_char(cur_i)=cur_c then if skip_byte(cur_i)<=stop_flag then
+ if op_byte(cur_i)>=kern_flag then
+ begin p:=new_kern(char_kern(cur_f)(cur_i));
+ link(p):=link(q); link(q):=p; return;
+ end
+ else begin check_interrupt; {allow a way out of infinite ligature loop}
+ case op_byte(cur_i) of
+ qi(1),qi(5): character(nucleus(q)):=rem_byte(cur_i); {\.{=:\?}, \.{=:\?>}}
+ qi(2),qi(6): character(nucleus(p)):=rem_byte(cur_i); {\.{\?=:}, \.{\?=:>}}
+ qi(3),qi(7),qi(11):begin r:=new_noad; {\.{\?=:\?}, \.{\?=:\?>}, \.{\?=:\?>>}}
+ character(nucleus(r)):=rem_byte(cur_i);
+ fam(nucleus(r)):=fam(nucleus(q));@/
+ link(q):=r; link(r):=p;
+ if op_byte(cur_i)<qi(11) then math_type(nucleus(r)):=math_char
+ else math_type(nucleus(r)):=math_text_char; {prevent combination}
+ end;
+ othercases begin link(q):=link(p);
+ character(nucleus(q)):=rem_byte(cur_i); {\.{=:}}
+ mem[subscr(q)]:=mem[subscr(p)]; mem[supscr(q)]:=mem[supscr(p)];@/
+ free_node(p,noad_size);
+ end
+ endcases;
+ if op_byte(cur_i)>qi(3) then return;
+ math_type(nucleus(q)):=math_char; goto restart;
+ end
+@z
+@x module 862
+@!q,@!r,@!s:pointer; {miscellaneous nodes of temporary interest}
+@y
+@!q,@!r,@!s,@!prev_s:pointer; {miscellaneous nodes of temporary interest}
+@z
+@x module 892
+nodes $p_a$ and~$p_b$ in the description above are placed into variables
+@y
+nodes $p_{a-1}$ and~$p_b$ in the description above are placed into variables
+@z
+@x ibid
+@!hc:array[0..65] of halfword; {word to be hyphenated}
+@y
+@!hc:array[0..65] of 0..256; {word to be hyphenated}
+@z
+@x ibid
+@!hu:array[1..63] of ASCII_code; {like |hc|, before conversion to lowercase}
+@y
+@!hu:array[0..63] of 0..256; {like |hc|, before conversion to lowercase}
+@z
+@x module 894
+s:=link(cur_p);
+@y
+prev_s:=cur_p; s:=link(prev_s);
+@z
+@x module 895
+label done,found,not_found,found1,exit;
+@y
+label common_ending,done,found,found1,not_found,not_found+1,exit;
+@z
+@x module 896
+ else if type(s)=ligature_node then
+ begin q:=lig_ptr(s); c:=qo(character(q)); hf:=font(q);
+ end
+@y
+ else if type(s)=ligature_node then
+ if lig_ptr(s)=null then goto continue
+ else begin q:=lig_ptr(s); c:=qo(character(q)); hf:=font(q);
+ end
+@z
+@x ibid
+continue: s:=link(s);
+@y
+continue: prev_s:=s; s:=link(prev_s);
+@z
+@x ibid
+ha:=s
+@y
+ha:=prev_s
+@z
+@x module 898
+begin j:=hn; q:=lig_ptr(s);
+if font(q)<>hf then goto done3;
+repeat c:=qo(character(q));
+if lc_code(c)=0 then goto done3;
+if j=63 then goto done3;
+incr(j); hu[j]:=c; hc[j]:=lc_code(c);@/
+q:=link(q);
+until q=null;
+@y
+begin if font(lig_char(s))<>hf then goto done3;
+j:=hn; q:=lig_ptr(s);
+while q>null do
+ begin c:=qo(character(q));
+ if lc_code(c)=0 then goto done3;
+ if j=63 then goto done3;
+ incr(j); hu[j]:=c; hc[j]:=lc_code(c);@/
+ q:=link(q);
+ end;
+@z
+@x module 900 gets three new global variables
+@y
+@!init_list:pointer; {list of punctuation characters preceding the word}
+@!init_lig:boolean; {does |init_list| represent a ligature?}
+@!init_lft:boolean; {if so, did the ligature involve a left boundary?}
+@z
+@x module 901
+@!q,@!r,@!s:pointer; {temporary registers for list manipulation}
+@y
+@!p,@!q,@!r,@!s:pointer; {temporary registers for list manipulation}
+@!bchar:halfword; {right boundary character of hyphenated word, or |non_char|}
+@z
+@x module 903 should be entirely replaced
+@y by the following:
+@ If hyphens are in fact going to be inserted, \TeX\ first deletes the
+subsequence of nodes between |ha| and~|hb|. An attempt is made to
+preserve the effect that implicit boundary characters and punctuation marks
+had on ligatures inside the hyphenated word, by storing a left boundary or
+preceding character in |hu[0]| and by storing a possible right boundary
+in |bchar|. We set |j:=0| if |hu[0]| is to be part of the reconstruction;
+otherwise |j:=1|.
+The variable |s| will point to the tail of the current hlist, and
+|q| will point to the node following |hb|, so that
+things can be hooked up after we reconstitute the hyphenated word.
+
+@<Replace nodes |ha..hb| by a sequence of nodes...@>=
+q:=link(hb); link(hb):=null; r:=link(ha); link(ha):=null; bchar:=non_char;
+if type(hb)=ligature_node then if odd(subtype(hb)) then
+ bchar:=font_bchar[hf];
+if is_char_node(ha) then
+ begin init_list:=ha; init_lig:=false; hu[0]:=qo(character(ha));
+ end
+else if type(ha)=ligature_node then
+ begin init_list:=lig_ptr(ha); init_lig:=true; init_lft:=(subtype(ha)>1);
+ hu[0]:=qo(character(lig_char(ha)));
+ if init_list=null then if init_lft then
+ begin hu[0]:=256; init_lig:=false;
+ end; {in this case a ligature will be reconstructed from scratch}
+ free_node(ha,small_node_size);
+ end
+else goto not_found+1; {no punctuation found}
+s:=cur_p; {we have |cur_p<>ha| because |type(cur_p)=glue_node|}
+while link(s)<>ha do s:=link(s);
+j:=0; goto common_ending;
+not_found+1: j:=1; s:=ha; init_list:=null;
+if not is_char_node(r) then if type(r)=ligature_node then
+ if subtype(r)>1 then
+ begin j:=0; hu[0]:=256; init_lig:=false;
+ end;
+common_ending: flush_node_list(r);
+@<Reconstitute nodes for the hyphenated word, inserting discretionary hyphens@>;
+flush_list(init_list)
+@z
+@x modules 905--911 are entirely replaced
+@y by the following new code:
+Still further complications arise in the presence of ligatures that do not
+delete the original characters. When punctuation precedes the word being
+hyphenated, \TeX's method is not perfect under all possible scenarios,
+because punctuation marks and letters can propagate information back and forth.
+For example, suppose the original pre-hyphenation pair
+\.{*a} changes to \.{*y} via a \.{\?=:} ligature, which changes to \.{xy}
+via a \.{=:\?} ligature; if $p_{a-1}=\.x$ and $p_a=\.y$, the reconstitution
+procedure isn't smart enough to obtain \.{xy} again. In such cases the
+font designer should include a ligature that goes from \.{xa} to \.{xy}.
+
+@ The processing is facilitated by a subroutine called |reconstitute|. Given
+a string of characters $x_j\ldots x_n$, there is a smallest index $m\ge j$
+such that the ``translation'' of $x_j\ldots x_n$ by ligatures and kerning
+has the form $y_1\ldots y_t$ followed by the translation of $x_{m+1}\ldots x_n$,
+where $y_1\ldots y_t$ is some nonempty sequence of character, ligature, and
+kern nodes. We call $x_j\ldots x_m$ a ``cut prefix'' of $x_j\ldots x_n$.
+For example, if $x_1x_2x_3=\.{fly}$, and if the font contains `fl' as a
+ligature and a kern between `fl' and `y', then $m=2$, $y=2$, and $y_1$ will
+be a ligature node for `fl' followed by an appropriate kern node~$y_2$.
+In the most common case, $x_j$~forms no ligature with $x_{j+1}$ and we
+simply have $m=j$, $y_1=x_j$. If $m<n$ we can repeat the procedure on
+$x_{m+1}\ldots x_n$ until the entire translation has been found.
+
+The |reconstitute| function returns the integer $m$ and puts the nodes
+$y_1\ldots y_t$ into a linked list starting at |link(hold_head)|,
+getting the input $x_j\ldots x_n$ from the |hu| array. If $x_j=256$,
+we consider $x_j$ to be an implicit left boundary character; in this
+case |j| must be strictly less than~|n|. There is a
+parameter |bchar|, which is either 256 or an implicit right boundary character
+assumed to be present just following~$x_n$. (The value |hu[n+1]| is never
+explicitly examined, but the algorithm imagines that |bchar| is there.)
+
+If there exists an index |k| in the range $j\le k\le m$ such that |hyf[k]|
+is odd and such that the result of reconstitute would have been different
+if $x_{k+1}$ had been |hchar|, then |reconstitute| sets |hyphen_passed|
+to the smallest such~|k|. Otherwise it sets |hyphen_passed| to zero.
+
+A special convention is used in the case |j=0|: Then we assume that the
+translation of |hu[0]| appears in a special list of charnodes starting at
+|init_list|; moreover, if |init_lig| is |true|, then |hu[0]| will be
+a ligature character, involving a left boundary if |init_lft| is |true|.
+This facility is provided for cases when a hyphenated
+word is preceded by punctuation (like single or double quotes) that might
+affect the translation of the beginning of the word.
+
+@<Glob...@>=
+@!hyphen_passed:small_number; {first hyphen in a ligature, if any}
+
+@ @<Declare the function called |reconstitute|@>=
+function reconstitute(@!j,@!n:small_number;@!bchar,@!hchar:halfword):
+ small_number;
+label continue,done;
+var @!p:pointer; {temporary register for list manipulation}
+@!t:pointer; {a node being appended to}
+@!q:four_quarters; {character information or a lig/kern instruction}
+@!cur_rh:halfword; {hyphen character for ligature testing}
+@!test_char:halfword; {hyphen or other character for ligature testing}
+@!w:scaled; {amount of kerning}
+@!k:font_index; {position of current lig/kern instruction}
+begin hyphen_passed:=0; t:=hold_head; w:=0; link(hold_head):=null;
+ {at this point |ligature_present=lft_hit=rt_hit=false|}
+@<Set up data structures with the cursor following position |j|@>;
+continue:@<If there's a ligature or kern at the cursor position, update the data
+ structures, possibly advancing~|j|; continue until the cursor moves@>;
+@<Append a ligature and/or kern to the translation;
+ |goto continue| if the stack of inserted ligatures is nonempty@>;
+reconstitute:=j;
+end;
+
+@ The reconstitution procedure shares many of the global data structures
+by which \TeX\ has processed the words before they were hyphenated.
+There is an implied ``cursor'' between characters |cur_l| and |cur_r|;
+these characters will be tested for possible ligature activity. If
+|ligature_present| then |cur_l| is a ligature character formed from the
+original characters following |cur_q| in the current translation list.
+There is a ``ligature stack'' between the cursor and character |j+1|,
+consisting of pseudo-ligature nodes linked together by their |link| fields.
+This stack is normally empty unless a ligature command has created a new
+character that will need to be processed later. A pseudo-ligature is
+a special node having a |character| field that represents a potential
+ligature and a |lig_ptr| field that points to a |char_node| or is |null|.
+We have
+$$|cur_r|=\cases{|character(lig_stack)|,&if |lig_stack>null|;\cr
+ |qi(hu[j+1])|,&if |lig_stack=null| and |j<n|;\cr
+ bchar,&if |lig_stack=null| and |j=n|.\cr}$$
+
+@<Glob...@>=
+@!cur_l,@!cur_r:halfword; {characters before and after the cursor}
+@!cur_q:pointer; {where a ligature should be detached}
+@!lig_stack:pointer; {unfinished business to the right of the cursor}
+@!ligature_present:boolean; {should a ligature node be made for |cur_l|?}
+@!lft_hit,@!rt_hit:boolean; {did we hit a ligature with a boundary character?}
+
+@ @d append_charnode_to_t(#)== begin link(t):=get_avail; t:=link(t);
+ font(t):=hf; character(t):=#;
+ end
+@d set_cur_r==begin if j<n then cur_r:=qi(hu[j+1])@+else cur_r:=bchar;
+ if odd(hyf[j]) then cur_rh:=hchar@+else cur_rh:=non_char;
+ end
+
+@<Set up data structures with the cursor following position |j|@>=
+cur_l:=qi(hu[j]); cur_q:=t;
+if j=0 then
+ begin ligature_present:=init_lig; p:=init_list;
+ if ligature_present then lft_hit:=init_lft;
+ while p>null do
+ begin append_charnode_to_t(character(p)); p:=link(p);
+ end;
+ end
+else if cur_l<non_char then append_charnode_to_t(cur_l);
+lig_stack:=null; set_cur_r
+
+@ We may want to look at the lig/kern program twice, once for a hyphen
+and once for a normal letter. (The hyphen might appear after the letter
+in the program, so we'd better not try to look for both at once.)
+
+@<If there's a ligature or kern at the cursor position, update...@>=
+if cur_l=non_char then
+ begin k:=bchar_label[hf];
+ if k=non_address then goto done@+else q:=font_info[k].qqqq;
+ end
+else begin q:=char_info(hf)(cur_l);
+ if char_tag(q)<>lig_tag then goto done;
+ k:=lig_kern_start(hf)(q); q:=font_info[k].qqqq;
+ if skip_byte(q)>stop_flag then
+ begin k:=lig_kern_restart(hf)(q); q:=font_info[k].qqqq;
+ end;
+ end; {now |k| is the starting address of the lig/kern program}
+if cur_rh<non_char then test_char:=cur_rh@+else test_char:=cur_r;
+loop@+begin if next_char(q)=test_char then if skip_byte(q)<=stop_flag then
+ if cur_rh<non_char then
+ begin hyphen_passed:=j; hchar:=non_char; cur_rh:=non_char;
+ goto continue;
+ end
+ else begin if hchar<non_char then if odd(hyf[j]) then
+ begin hyphen_passed:=j; hchar:=non_char;
+ end;
+ if op_byte(q)<kern_flag then
+ @<Carry out a ligature replacement, updating the cursor structure
+ and possibly advancing~|j|; |goto continue| if the cursor doesn't
+ advance, otherwise |goto done|@>;
+ w:=char_kern(hf)(q); goto done; {this kern will be inserted below}
+ end;
+ if skip_byte(q)>=stop_flag then
+ if cur_rh=non_char then goto done
+ else begin cur_rh:=non_char; goto continue;
+ end;
+ k:=k+qo(skip_byte(q))+1; q:=font_info[k].qqqq;
+ end;
+done:
+
+@ @d wrap_lig(#)==if ligature_present then
+ begin p:=new_ligature(hf,cur_l,link(cur_q));
+ if lft_hit then
+ begin subtype(p):=2; lft_hit:=false;
+ end;
+ if # then if lig_stack=null then
+ begin incr(subtype(p)); rt_hit:=false;
+ end;
+ link(cur_q):=p; t:=p; ligature_present:=false;
+ end
+@d pop_lig_stack==begin if lig_ptr(lig_stack)>null then
+ begin link(t):=lig_ptr(lig_stack); {this is a charnode for |hu[j+1]|}
+ t:=link(t); incr(j);
+ end;
+ p:=lig_stack; lig_stack:=link(p); free_node(p,small_node_size);
+ if lig_stack=null then set_cur_r@+else cur_r:=character(lig_stack);
+ end {if |lig_stack| isn't |null| we have |cur_rh=non_char|}
+
+@<Append a ligature and/or kern to the translation...@>=
+wrap_lig(rt_hit);
+if w<>0 then
+ begin link(t):=new_kern(w); t:=link(t); w:=0;
+ end;
+if lig_stack>null then
+ begin cur_q:=t; cur_l:=character(lig_stack); ligature_present:=true;
+ pop_lig_stack; goto continue;
+ end
+
+@ @<Carry out a ligature replacement, updating the cursor structure...@>=
+begin if cur_l=non_char then lft_hit:=true;
+if j=n then if lig_stack=null then rt_hit:=true;
+check_interrupt; {allow a way out in case there's an infinite ligature loop}
+case op_byte(q) of
+qi(1),qi(5):begin cur_l:=rem_byte(q); {\.{=:\?}, \.{=:\?>}}
+ ligature_present:=true;
+ end;
+qi(2),qi(6):begin cur_r:=rem_byte(q); {\.{\?=:}. \.{\?=:>}}
+ if lig_stack>null then character(lig_stack):=cur_r
+ else begin lig_stack:=new_lig_item(cur_r);
+ if j=n then bchar:=non_char
+ else begin p:=get_avail; lig_ptr(lig_stack):=p;
+ character(p):=qi(hu[j+1]); font(p):=hf;
+ end;
+ end;
+ end;
+qi(3):begin cur_r:=rem_byte(q); {\.{\?=:\?}}
+ p:=lig_stack; lig_stack:=new_lig_item(cur_r); link(lig_stack):=p;
+ end;
+qi(7),qi(11):begin wrap_lig(false); {\.{\?=:\?>}, \.{\?=:\?>>}}
+ cur_q:=t; cur_l:=rem_byte(q); ligature_present:=true;
+ end;
+othercases begin cur_l:=rem_byte(q); ligature_present:=true; {\.{=:}}
+ if lig_stack>null then pop_lig_stack
+ else if j=n then goto done
+ else begin append_charnode_to_t(cur_r); incr(j); set_cur_r;
+ end;
+ end
+endcases;
+if op_byte(q)>qi(4) then if op_byte(q)<>qi(7) then goto done;
+goto continue;
+end
+@z
+@x module 912
+@!c:ASCII_code; {character temporarily replaced by a hyphen}
+@y
+@!c:ASCII_code; {character temporarily replaced by a hyphen}
+@!c_loc:0..63; {where that character came from}
+@!r_count:integer; {replacement count for discretionary}
+@z
+@x modules 913--918 are to be completely replaced
+@y by the following code:
+@ When the following code is performed, |hyf[0]| and |hyf[hn]| will be zero.
+
+@<Reconstitute nodes for the hyphenated word...@>=
+repeat l:=j; j:=reconstitute(j,hn,bchar,qi(hyf_char))+1;
+if hyphen_passed=0 then
+ begin link(s):=link(hold_head);
+ while link(s)>null do s:=link(s);
+ if odd(hyf[j-1]) then
+ begin l:=j; hyphen_passed:=j-1; link(hold_head):=null;
+ end;
+ end;
+if hyphen_passed>0 then
+ @<Create and append a discretionary node as an alternative to the
+ unhyphenated word, and continue to develop both branches until they
+ become equivalent@>;
+until j>hn;
+link(s):=q
+
+@ @d advance_major_tail==begin major_tail:=link(major_tail); incr(r_count);
+ end
+
+@<Create and append a discretionary node as an alternative...@>=
+begin r:=get_node(small_node_size);
+link(r):=link(hold_head); type(r):=disc_node;
+major_tail:=r; r_count:=0;
+while link(major_tail)>null do advance_major_tail;
+i:=hyphen_passed;
+@<Put the \(c)characters |hu[l..i]| and a hyphen into |pre_break(r)|@>;
+@<Put the \(c)characters |hu[i+1..@,]| into |post_break(r)|, appending to this
+ list and to |major_tail| until synchronization has been achieved@>;
+@<Move pointer |s| to the end of the current list, and set |replace_count(r)|
+ appropriately@>;
+end
+
+@ The new hyphen might combine with the previous character via ligature
+or kern. At this point we have |l-1<=i<=j| and |i<hn|.
+
+@<Put the \(c)characters |hu[l..i]| and a hyphen into |pre_break(r)|@>=
+minor_tail:=null; pre_break(r):=null; hyf_node:=new_character(hf,hyf_char);
+if hyf_node<>null then
+ begin incr(i); c:=hu[i]; hu[i]:=hyf_char; free_avail(hyf_node);
+ end;
+while l<=i do
+ begin l:=reconstitute(l,i,font_bchar[hf],non_char)+1;
+ if link(hold_head)>null then
+ begin if minor_tail=null then pre_break(r):=link(hold_head)
+ else link(minor_tail):=link(hold_head);
+ minor_tail:=link(hold_head);
+ while link(minor_tail)>null do minor_tail:=link(minor_tail);
+ end;
+ end;
+if hyf_node<>null then
+ begin hu[i]:=c; {restore the character in the hyphen position}
+ l:=i; decr(i);
+ end
+
+@ The synchronization algorithm begins with |l=i+1<=j|.
+
+@<Put the \(c)characters |hu[i+1..@,]| into |post_break(r)|...@>=
+minor_tail:=null; post_break(r):=null; c_loc:=0;
+if bchar_label[hf]<non_address then {put left boundary at beginning of new line}
+ begin decr(l); c:=hu[l]; c_loc:=l; hu[l]:=256;
+ end;
+while l<j do
+ begin repeat l:=reconstitute(l,hn,bchar,non_char)+1;
+ if c_loc>0 then
+ begin hu[c_loc]:=c; c_loc:=0;
+ end;
+ if link(hold_head)>null then
+ begin if minor_tail=null then post_break(r):=link(hold_head)
+ else link(minor_tail):=link(hold_head);
+ minor_tail:=link(hold_head);
+ while link(minor_tail)>null do minor_tail:=link(minor_tail);
+ end;
+ until l>=j;
+ while l>j do
+ @<Append characters of |hu[j..@,]| to |major_tail|, advancing~|j|@>;
+ end
+
+@ @<Append characters of |hu[j..@,]|...@>=
+begin j:=reconstitute(j,hn,bchar,non_char)+1;
+link(major_tail):=link(hold_head);
+while link(major_tail)>null do advance_major_tail;
+end
+
+@ Ligature insertion can cause a word to grow exponentially in size. Therefore
+we must test the size of |r_count| here, even though the hyphenated text
+was at most 63 characters long.
+
+@<Move pointer |s| to the end of the current list...@>=
+if r_count>127 then {we have to forget the discretionary hyphen}
+ begin link(s):=link(r); link(r):=null; flush_node_list(r);
+ end
+else begin link(s):=r; replace_count(r):=r_count;
+ end;
+s:=major_tail
+@z
+@x module 1030
+@d main_loop=70 {go here to typeset |cur_chr| in the current font}
+@d main_loop_1=71 {like |main_loop|, but |(f,c)| = current font and char}
+@d main_loop_2=72 {like |main_loop_1|, but |c| is known to be in range}
+@d main_loop_3=73 {like |main_loop_2|, but several variables are set up}
+@d append_normal_space=74 {go here to append a normal space between words}
+@y
+@d main_loop=70 {go here to typeset a string of consecutive characters}
+@d main_loop_wrapup=80 {go here to finish a character or ligature}
+@d main_loop_move=90 {go here to advance the ligature cursor}
+@d main_loop_move_lig=95 {same, when advancing past a generated ligature}
+@d main_loop_lookahead=100 {go here to bring in another character, if any}
+@d main_lig_loop=110 {go here to check for ligatures or kerning}
+@d append_normal_space=120 {go here to append a normal space between words}
+@z
+@x ibid
+label big_switch,reswitch,main_loop,main_loop_1,main_loop_2,main_loop_3,
+@y
+label big_switch,reswitch,main_loop,main_loop_wrapup,
+ main_loop_move,main_loop_move+1,main_loop_move+2,main_loop_move_lig,
+ main_loop_lookahead,main_loop_lookahead+1,
+ main_lig_loop,main_lig_loop+1,main_lig_loop+2,
+@z
+@x ibid
+@<Local variables for the inner loop of |main_control|@>@;
+@y
+@z
+@x ibid
+hmode+char_num: begin scan_char_num; cur_chr:=cur_val; goto main_loop;
+ end;
+@y
+hmode+char_num: begin scan_char_num; cur_chr:=cur_val; goto main_loop;@+end;
+hmode+no_boundary: begin get_x_token;
+ if (cur_cmd=letter)or(cur_cmd=other_char)or(cur_cmd=char_given)or
+ (cur_cmd=char_num) then cancel_boundary:=true;
+ goto reswitch;
+ end;
+@z
+@x modules 1032--1040 are all to be replaced
+@y by the following code:
+@ The following part of the program was first written in a structured
+manner, according to the philosophy that ``premature optimization is
+the root of all evil.'' Then it was rearranged into pieces of
+spaghetti so that the most common actions could proceed with little or
+no redundancy.
+
+The original unoptimized form of this algorithm resembles the
+|reconstitute| procedure, which was described earlier in connection with
+hyphenation. Again we have an implied ``cursor`` between characters
+|cur_l| and |cur_r|. The main difference is that the |lig_stack| can now
+contain a charnode as well as pseudo-ligatures; that stack is now
+usually nonempty, because the next character of input (if any) has been
+appended to it. In |main_control| we have
+$$|cur_r|=\cases{|character(lig_stack)|,&if |lig_stack>null|;\cr
+ |font_bchar[cur_font]|,&otherwise.\cr}$$
+Several additional global variables are needed.
+
+@<Glob...@>=
+@!main_f:internal_font_number; {the current font}
+@!main_i:four_quarters; {character information bytes for |cur_l|}
+@!main_j:four_quarters; {ligature/kern command}
+@!main_k:font_index; {index into |font_info|}
+@!main_p:pointer; {temporary register for list manipulation}
+@!main_s:integer; {space factor value}
+@!bchar:halfword; {right boundary character of current font, or |non_char|}
+@!false_bchar:halfword; {nonexistent character matching |bchar|, or |non_char|}
+@!cancel_boundary:boolean; {should the left boundary be ignored?}
+@!ins_disc:boolean; {should we insert a discretionary node?}
+
+@ The boolean variables of the main loop are normally false, and always reset
+to false before the loop is left. That saves us the extra work of initializing
+each time.
+
+@<Set init...@>=
+ligature_present:=false; cancel_boundary:=false; lft_hit:=false; rt_hit:=false;
+ins_disc:=false;
+
+@ We leave |space_factor| unchanged if |sf_code(cur_chr)=0|; otherwise we
+set it to |sf_code(cur_chr)|, except that the space factor never changes
+from a value less than 1000 to a value exceeding 1000. The most common
+case is |sf_code(cur_chr)=1000|, so we want that case to be fast.
+
+The overall structure of the main loop is presented here. Some program labels
+are inside the individual sections.
+
+@d adjust_space_factor==@t@>@;@/
+ main_s:=sf_code(cur_chr);
+ if main_s=1000 then space_factor:=1000
+ else if main_s<1000 then
+ begin if main_s>0 then space_factor:=main_s;
+ end
+ else if space_factor<1000 then space_factor:=1000
+ else space_factor:=main_s
+
+@<Append character |cur_chr|...@>=
+adjust_space_factor;@/
+main_f:=cur_font;
+bchar:=font_bchar[main_f]; false_bchar:=font_false_bchar[main_f];
+if mode>0 then if language<>clang then fix_language;
+fast_get_avail(lig_stack); font(lig_stack):=main_f; cur_l:=qi(cur_chr);
+character(lig_stack):=cur_l;@/
+cur_q:=tail;
+if cancel_boundary then
+ begin cancel_boundary:=false; main_k:=non_address;
+ end
+else main_k:=bchar_label[main_f];
+if main_k=non_address then goto main_loop_move+2; {no left boundary processing}
+cur_r:=cur_l; cur_l:=non_char;
+goto main_lig_loop+1; {begin with cursor after left boundary}
+@#
+main_loop_wrapup:@<Make a ligature node, if |ligature_present|;
+ insert a null discretionary, if appropriate@>;
+main_loop_move:@<If the cursor is immediately followed by the right boundary,
+ |goto reswitch|; if it's followed by an invalid character, |goto big_switch|;
+ otherwise move the cursor one step to the right and |goto main_lig_loop|@>;
+main_loop_lookahead:@<Look ahead for another character, or leave |lig_stack|
+ empty if there's none there@>;
+main_lig_loop:@<If there's a ligature/kern command relevant to |cur_l| and
+ |cur_r|, adjust the text appropriately; exit to |main_loop_wrapup|@>;
+main_loop_move_lig:@<Move the cursor past a pseudo-ligature, then
+ |goto main_loop_lookahead| or |main_lig_loop|@>
+
+@ If the current horizontal list is empty, the reference to |character(tail)|
+here is not strictly legal, since |tail| will be a node freshly returned by
+|get_avail|. But this should cause no problem on most implementations, and we
+do want the inner loop to be fast.
+@^dirty Pascal@>
+
+A discretionary break is not inserted for an explicit hyphen when we are in
+restricted horizontal mode. In particular, this avoids putting discretionary
+nodes inside of other discretionaries.
+
+@d pack_lig(#)== {the parameter is either |rt_hit| or |false|}
+ begin main_p:=new_ligature(main_f,cur_l,link(cur_q));
+ if lft_hit then
+ begin subtype(main_p):=2; lft_hit:=false;
+ end;
+ if # then if lig_stack=null then
+ begin incr(subtype(main_p)); rt_hit:=false;
+ end;
+ link(cur_q):=main_p; tail:=main_p; ligature_present:=false;
+ end
+
+@d wrapup(#)==if cur_l<non_char then
+ begin if character(tail)=qi(hyphen_char[main_f]) then if link(cur_q)>null then
+ ins_disc:=true;
+ if ligature_present then pack_lig(#);
+ if ins_disc then
+ begin ins_disc:=false;
+ if mode>0 then tail_append(new_disc);
+ end;
+ end
+
+@<Make a ligature node, if |ligature_present|;...@>=
+wrapup(rt_hit)
+
+@ @<If the cursor is immediately followed by the right boundary...@>=
+if lig_stack=null then goto reswitch;
+cur_q:=tail; cur_l:=cur_r; {or |character(lig_stack)|}
+main_loop_move+1:if not is_char_node(lig_stack) then goto main_loop_move_lig;
+main_loop_move+2:if(cur_chr<font_bc[main_f])or(cur_chr>font_ec[main_f]) then
+ begin char_warning(main_f,cur_chr); free_avail(lig_stack); goto big_switch;
+ end;
+main_i:=char_info(main_f)(cur_l);
+if not char_exists(main_i) then
+ begin char_warning(main_f,cur_chr); free_avail(lig_stack); goto big_switch;
+ end;
+tail_append(lig_stack) {|main_loop_lookahead| is next}
+
+@ Here we are at |main_loop_move_lig|.
+When we begin this code we have |cur_l=character(lig_stack)| and |cur_q=tail|.
+
+@<Move the cursor past a pseudo-ligature...@>=
+main_p:=lig_ptr(lig_stack);
+if main_p>null then tail_append(main_p);
+temp_ptr:=lig_stack; lig_stack:=link(temp_ptr);
+free_node(temp_ptr,small_node_size);
+main_i:=char_info(main_f)(cur_l); ligature_present:=true;
+if lig_stack=null then
+ if main_p>null then goto main_loop_lookahead
+ else cur_r:=bchar
+else cur_r:=character(lig_stack);
+goto main_lig_loop
+
+@ The result of \.{\\char} can participate in a ligature or kern, so we must
+look ahead for it.
+
+@<Look ahead for another character...@>=
+get_next; {set only |cur_cmd| and |cur_chr|, for speed}
+if cur_cmd=letter then goto main_loop_lookahead+1;
+if cur_cmd=other_char then goto main_loop_lookahead+1;
+if cur_cmd=char_given then goto main_loop_lookahead+1;
+x_token; {now expand and set |cur_cmd|, |cur_chr|, |cur_tok|}
+if cur_cmd=letter then goto main_loop_lookahead+1;
+if cur_cmd=other_char then goto main_loop_lookahead+1;
+if cur_cmd=char_given then goto main_loop_lookahead+1;
+if cur_cmd=char_num then
+ begin scan_char_num; cur_chr:=cur_val; goto main_loop_lookahead+1;
+ end;
+if cur_cmd=no_boundary then bchar:=non_char;
+cur_r:=bchar; lig_stack:=null; goto main_lig_loop;
+main_loop_lookahead+1: adjust_space_factor;
+fast_get_avail(lig_stack); font(lig_stack):=main_f;
+cur_r:=qi(cur_chr); character(lig_stack):=cur_r;
+if cur_r=false_bchar then cur_r:=non_char {this prevents spurious ligatures}
+
+@ Even though comparatively few characters have a lig/kern program, several
+of the instructions here count as part of \TeX's inner loop, since a
+potentially long sequential search must be performed. For example, tests with
+Computer Modern Roman showed that about 40 per cent of all characters
+actually encountered in practice had a lig/kern program, and that about four
+lig/kern commands were investigated for every such character.
+
+At the beginning of this code we have |main_i=char_info(main_f)(cur_l)|.
+
+@<If there's a ligature/kern command...@>=
+if char_tag(main_i)<>lig_tag then goto main_loop_wrapup;
+main_k:=lig_kern_start(main_f)(main_i); main_j:=font_info[main_k].qqqq;
+if skip_byte(main_j)<=stop_flag then goto main_lig_loop+2;
+main_k:=lig_kern_restart(main_f)(main_j);
+main_lig_loop+1:main_j:=font_info[main_k].qqqq;
+main_lig_loop+2:if next_char(main_j)=cur_r then
+ if skip_byte(main_j)<=stop_flag then
+ @<Do ligature or kern command, returning to |main_lig_loop|
+ or |main_loop_wrapup| or |main_loop_move|@>;
+if skip_byte(main_j)=qi(0) then incr(main_k)
+else begin if skip_byte(main_j)>=stop_flag then goto main_loop_wrapup;
+ main_k:=main_k+qo(skip_byte(main_j))+1;
+ end;
+goto main_lig_loop+1
+
+@ When a ligature or kern instruction matches a character, we know from
+|read_font_info| that the character exists in the font, even though we
+haven't verified its existence in the normal way.
+
+This section could be made into a subroutine, if the code inside
+|main_control| needs to be shortened.
+
+\chardef\?='174 % vertical line to indicate character retention
+
+@<Do ligature or kern command...@>=
+begin if op_byte(main_j)>=kern_flag then
+ begin wrapup(rt_hit);
+ tail_append(new_kern(char_kern(main_f)(main_j))); goto main_loop_move;
+ end;
+if cur_l=non_char then lft_hit:=true
+else if lig_stack=null then rt_hit:=true;
+check_interrupt; {allow a way out in case there's an infinite ligature loop}
+case op_byte(main_j) of
+qi(1),qi(5):begin cur_l:=rem_byte(main_j); {\.{=:\?}, \.{=:\?>}}
+ main_i:=char_info(main_f)(cur_l); ligature_present:=true;
+ end;
+qi(2),qi(6):begin cur_r:=rem_byte(main_j); {\.{\?=:}, \.{\?=:>}}
+ if lig_stack=null then {right boundary character is being consumed}
+ begin lig_stack:=new_lig_item(cur_r); bchar:=non_char;
+ end
+ else if is_char_node(lig_stack) then {|link(lig_stack)=null|}
+ begin main_p:=lig_stack; lig_stack:=new_lig_item(cur_r);
+ lig_ptr(lig_stack):=main_p;
+ end
+ else character(lig_stack):=cur_r;
+ end;
+qi(3):begin cur_r:=rem_byte(main_j); {\.{\?=:\?}}
+ main_p:=lig_stack; lig_stack:=new_lig_item(cur_r);
+ link(lig_stack):=main_p;
+ end;
+qi(7),qi(11):begin wrapup(false); {\.{\?=:\?>}, \.{\?=:\?>>}}
+ cur_q:=tail; cur_l:=rem_byte(main_j);
+ main_i:=char_info(main_f)(cur_l); ligature_present:=true;
+ end;
+othercases begin cur_l:=rem_byte(main_j); ligature_present:=true; {\.{=:}}
+ if lig_stack=null then goto main_loop_wrapup
+ else goto main_loop_move+1;
+ end
+endcases;
+if op_byte(main_j)>qi(4) then
+ if op_byte(main_j)<>qi(7) then goto main_loop_wrapup;
+if cur_l<non_char then goto main_lig_loop;
+main_k:=bchar_label[main_f]; goto main_lig_loop+1;
+end
+@z
+% HINTS for making main_control shorter if you need to conserve space:
+% (1) make pack_lig(#) a procedure call instead of a macro call
+% (2) make the code of @<Do ligature...@> a function that returns one of
+% four values; you goto a label based on the value returned.
+@x module 1042
+begin p:=font_glue[cur_font];
+if p=null then
+ begin f:=cur_font; p:=new_spec(zero_glue); k:=param_base[f]+space_code;
+ width(p):=font_info[k].sc; {that's |space(f)|}
+ stretch(p):=font_info[k+1].sc; {and |space_stretch(f)|}
+ shrink(p):=font_info[k+2].sc; {and |space_shrink(f)|}
+ font_glue[f]:=p;
+@y
+begin main_p:=font_glue[cur_font];
+if main_p=null then
+ begin main_p:=new_spec(zero_glue); main_k:=param_base[cur_font]+space_code;
+ width(main_p):=font_info[main_k].sc; {that's |space(cur_font)|}
+ stretch(main_p):=font_info[main_k+1].sc; {and |space_stretch(cur_font)|}
+ shrink(main_p):=font_info[main_k+2].sc; {and |space_shrink(cur_font)|}
+ font_glue[cur_font]:=main_p;
+@z
+@x module 1045
+any_mode(relax),vmode+spacer,mmode+spacer,mmode+no_boundary:do_nothing;
+@y
+any_mode(relax),vmode+spacer,mmode+spacer:do_nothing;
+@z
+@x module 1090
+ vmode+ex_space:@t@>@;@/
+@y
+ vmode+ex_space,vmode+no_boundary:@t@>@;@/
+@z
+@x module 1322
+dump_int(font_glue[k]);@/
+@y
+dump_int(font_glue[k]);@/
+dump_int(bchar_label[k]);
+dump_int(font_bchar[k]);
+dump_int(font_false_bchar[k]);@/
+@z
+@x module 1323
+undump(min_halfword)(lo_mem_max)(font_glue[k]);@/
+@y
+undump(min_halfword)(lo_mem_max)(font_glue[k]);@/
+undump(0)(font_mem_size)(bchar_label[k]);
+undump(min_quarterword)(non_char)(font_bchar[k]);
+undump(min_quarterword)(non_char)(font_false_bchar[k]);
+@z
+
+363. New \inputlineno feature desired by Spivak
+@x module 416 gets a new definition and a new statement
+@y
+@d input_line_no_code=glue_val+1 {code for \.{\\inputlineno}}
+primitive("inputlineno",last_item,input_line_no_code);
+@!@:input_line_no_}{\.{\\inputlineno} primitive@>
+@z and module 417 changes in the obvious way
+@x module 424 gets new code at the beginning
+@y
+if cur_chr>glue_val then
+ begin cur_val:=line; cur_val_level:=int_val;
+ end
+else
+@z
+
+364. New feature \holdinginserts suggested by Mittelbach.
+@x modules 236--238 get a new integer parameter
+@d int_pars=53 {total number of integer parameters}
+@y
+@d holding_inserts_code=53 {do not remove insertion nodes from \.{\\box255}}
+@d int_pars=54 {total number of integer parameters}
+@z and appropriate further lines are added to match all the other parameters
+@x module 1014
+@<Prepare all the boxes involved in insertions to act as queues@>;
+q:=hold_head; link(q):=null; prev_p:=page_head; p:=link(prev_p);
+while p<>best_page_break do
+ begin if type(p)=ins_node then @<Either insert the material
+ specified by node |p| into the appropriate box, or
+ hold it for the next page; also delete node |p| from
+ the current page@>
+@y
+if holding_inserts<=0 then
+ @<Prepare all the boxes involved in insertions to act as queues@>;
+q:=hold_head; link(q):=null; prev_p:=page_head; p:=link(prev_p);
+while p<>best_page_break do
+ begin if type(p)=ins_node then
+ begin if holding_inserts<=0 then
+ @<Either insert the material specified by node |p| into the
+ appropriate box, or hold it for the next page;
+ also delete node |p| from the current page@>;
+ end
+@z
+% also insert begin...end around the Pascal code of module 1018
+
+365. New \badness feature (which I'd been resisting for years)
+@x module 416 gets a new definition and a new statement
+@y
+@d badness_code=glue_val+2 {code for \.{\\badness}}
+primitive("badness",last_item,badness_code);
+@!@:badness_}{\.{\\badness} primitive@>
+@z and module 417 changes in the obvious way
+@x module 424 (the new code just added in #363)
+ begin cur_val:=line; cur_val_level:=int_val;
+@y
+ begin if cur_chr=input_line_no_code then cur_val:=line
+ else cur_val:=last_badness; {|cur_chr=badness_code|}
+ cur_val_level:=int_val;
+@z
+@x module 646 gets a new global variable
+@y
+@!last_badness:integer; {badness of the most recently packaged box}
+@z
+@x module 648
+@ @<Set init...@>=adjust_tail:=null;
+@y
+@ @<Set init...@>=adjust_tail:=null; last_badness:=0;
+@z
+@x modules 649 and 668
+@!b:integer; {badness of the new box}
+begin r:=get_node(box_node_size); type(r):=hlist_node;
+@y (except it's vlist_node in 668)
+begin last_badness:=0; r:=get_node(box_node_size); type(r):=hlist_node;
+@z (except it's vlist_node in 668)
+% change b to last_badness in modules 660&674 (4 times), 667&678 (3 times)
+@x modules 658 and 673
+if (hbadness<inf_bad)and(o=normal)and(list_ptr(r)<>null) then
+@y (except it's vbadness in 673)
+if o=normal then if list_ptr(r)<>null then
+@z
+@x modules 664 and 676
+ begin set_glue_ratio_one(glue_set(r)); {this is the maximum shrinkage}
+@y
+ begin last_badness:=1000000;
+ set_glue_ratio_one(glue_set(r)); {use the maximum shrinkage}
+@z
+@x ibid
+else if (hbadness<100)and(o=normal)and(list_ptr(r)<>null) then
+@y (except it's vbadness in 676)
+else if o=normal then if list_ptr(r)<>null then
+@z
+
+366. New \emergencystretch feature
+@x modules 247--248 get a new dimen parameter
+@d dimen_pars=20 {total number of dimension parameters}
+@y
+@d emergency_stretch_code=20 {reduces badnesses on final pass of line-breaking}
+@d dimen_pars=21 {total number of dimension parameters}
+@z and appropriate further lines are added to match all the other parameters
+@x module 828
+@!second_pass:boolean; {is this our second attempt to break this paragraph?}
+@y
+@!second_pass:boolean; {is this our second attempt to break this paragraph?}
+@!final_pass:boolean; {is this our final attempt to break this paragraph?}
+@z
+% change second_pass to final_pass in modules 854 and 873
+@x module 863
+ second_pass:=false;
+ end
+else begin threshold:=tolerance; second_pass:=true;
+@y
+ second_pass:=false; final_pass:=false;
+ end
+else begin threshold:=tolerance; second_pass:=true;
+ final_pass:=(emergency_stretch<=0);
+@z
+@x ibid
+ @!stat if tracing_paragraphs>0 then print_nl("@@secondpass");@;@+tats@/
+ threshold:=tolerance; second_pass:=true; {if at first you don't
+ succeed, \dots}
+@y
+ if not second_pass then
+ begin@!stat if tracing_paragraphs>0 then print_nl("@@secondpass");@;@+tats@/
+ threshold:=tolerance; second_pass:=true; final_pass:=(emergency_stretch<=0);
+ end {if at first you don't succeed, \dots}
+ else begin @!stat if tracing_paragraphs>0 then
+ print_nl("@@finalpass");@;@+tats@/
+ background[2]:=background[2]+emergency_stretch; final_pass:=true;
+ end;
+@z
+
+367. New \errorcontextlines feature suggested by a TUG participant
+@x modules 236--238 get a new integer parameter
+@d int_pars=54 {total number of integer parameters}
+@y
+@d error_context_lines_code=54 {maximum intermediate line pairs shown}
+@d int_pars=55 {total number of integer parameters}
+@z and appropriate further lines are added to match all the other parameters
+@x module 311
+@<Local variables for formatting calculations@>@/
+begin base_ptr:=input_ptr; input_stack[base_ptr]:=cur_input;
+ {store current state}
+loop@+begin cur_input:=input_stack[base_ptr]; {enter into the context}
+ @<Display the current context@>;
+ if (state<>token_list) then
+ if (name>17) or (base_ptr=0) then goto done;
+@y
+@!nn:integer; {number of contexts shown so far, less one}
+@!bottom_line:boolean; {have we reached the final context to be shown?}
+@<Local variables for formatting calculations@>@/
+begin base_ptr:=input_ptr; input_stack[base_ptr]:=cur_input;
+ {store current state}
+nn:=-1; bottom_line:=false;
+loop@+begin cur_input:=input_stack[base_ptr]; {enter into the context}
+ if (state<>token_list) then
+ if (name>17) or (base_ptr=0) then bottom_line:=true;
+ if (base_ptr=input_ptr)or bottom_line or(nn<error_context_lines) then
+ @<Display the current context@>
+ else if nn=error_context_lines then
+ begin print_nl("..."); incr(nn); {omitted if |error_context_lines<0|}
+ end;
+ if bottom_line then goto done;
+@z
+% also insert begin...end around the Pascal code of module 312
+% and add the statement "incr(nn)" to that module
+
+368. char_warning inside hyphenation could clobber old_setting
+@x module 863
+done: @!stat if tracing_paragraphs>0 then end_diagnostic(true);@;@+tats@/
+@y
+done: @!stat if tracing_paragraphs>0 then
+ begin end_diagnostic(true); normalize_selector;
+ end;@+tats@/
+@z
+
+369. Make ".fmt" more easily switchable (Don Hosek).
+@x module 520 gets a new definition
+@y
+@d format_extension=".fmt" {the extension, as a \.{WEB} constant}
+@z now replace ".fmt" by format_extension in modules 529 and 1328.
+
+370. Possible range check on weird nullfont (Breitenlohner, 16 Oct 89).
+@x module 565
+if (bc>ec+1)or(ec>255) then abort;
+@y
+if (bc>ec+1)or(ec>255) then abort;
+if bc>255 then {|bc=256| and |ec=255|}
+ begin bc:=1; ec:=0;
+ end;
+@z
+
+371. (I sincerely hope that there won't be any more)
+
+* Possibly nice ideas that will not be implemented
+
+. Classes of marks analogous to classes of insertions
+
+. \showcontext to show the current location without stopping for error
+
+. \everyeof to insert tokens before an \input file ends
+ (strange example: \everyeof{\noexpand} will allow things
+ like \xdef\a{\input foo}!)
+
+. generalize \leftskip and \rightskip to token lists (problems with
+ displayed math then)
+
+. generalize \widowline and \clubline to go further into a paragraph
+
+* Bad ideas that will not be implemented
+
+. several people want to be able to remove arbitrary elements of lists,
+ but that must never be done because some of those elements (e.g. kerns
+ for accents) depend on floating point arithmetic
+
+. if anybody wants letter spacing desperately they should put it in their own
+ private version (e.g. generalize the hpack routine) and NOT call it TeX.