MODULE PSDVI;

(* Author:         Andrew Trevorrow
   Implementation: University of Hamburg Modula-2 under VAX/VMS version 4
   Date Started:   August, 1986
   Released:       September, 1986 (version 1.0)

   Description:
   PSDVI reads a TeX DVI file and creates a corresponding PostScript file.
   This output file needs to be prefixed with some PostScript code.
   The /HEADER option can be used to include any desired file.
   PSDVI can be used by itself (see PSDVI.HLP) or as part of the
   PSPRINT system (see the PSPRINT User Guide and System Guide).
   Much of the code has been borrowed from DVItoVDU.

   Notes:
 - Debugging code is bracketed by (* DEBUG *) ... (* GUBED *).
   This code will be disabled in the final working version.
 - System-dependent code is indicated by the string "SYSDEP".
 - Uncertain or unfinished code is indicated by the strings "???" and "!!!".
 - Procedures are defined in a top-down manner: each procedure is usually
   defined as soon as possible after its first use.
 - The above notes also apply to the local modules used by PSDVI.

   Revised:
   December, 1986
 - PXLReader has become FontReader and can handle other font formats.
   All font-dependent code has been moved into FontReader.
 - Use LoadBitmap from FontReader instead of LoadPSChar from PSWriter
   to output PostScript code for each character bitmap.
   Unlike DVItoVDU, PSDVI does not need to store each bitmap for later use.
 - Released version 1.1 in January, 1987

   November, 1987 (while at The Open University)
 - Import tfmdir (for display in ShowOptions) and conserveVM from Options.
 - Import SaveVM and RestoreVM from PSWriter.
 - Import SetPostScriptChar from PSWriter; it is used (instead of
   SetBitmapChar) to typeset characters from a resident PostScript font.
 - Use conserveVM flag to call a different sequence of PSWriter
   routines if the user wants to conserve virtual memory.
 - Use psfont flag (set in BuildFontSpec in FontReader) to control the
   sequence of PSWriter routines for resident PostScript fonts.
 - Added ShowPtSize routine to show requested pt size for PostScript fonts.
 - Added PSDVI banner line to start of ShowOptions showing version number.
 - Released version 2.0 in December, 1987

   June--August, 1988 (while at Aston University)
 - Added /psprefix qualifier so that sites have some flexibility in choosing
   the prefix that indicates a PostScript font.
 - Added /increment qualifier to enhance page selection for duplex printing.
 - Added /hoffset and /voffset qualifiers to allow shifting of page.
 - Removed "Creating ..." message due to changes in *_PRINT.COM files.
 - No longer use StartLn/WriteBuffer/pagesperline.
   Page numbers now appear on separate lines.
 - Released version 3.0 in August, 1988

   September--October, 1989 (while at Aston University, 2nd time)
 - \special info now added to tail of speciallist.
 - Released version 3.1 in October, 1989
*)


FROM Storage IMPORT
   ALLOCATE, DEALLOCATE;   (* for NEW and DISPOSE *)


(* SYSDEP: Modula-2 avoids the problem of system dependence by simply
   not providing any input/output routines etc.  The above importations
   are highly system-dependent.

   The following modules are kept with the file you are now reading.
   See the .DEF files for details on how the imported identifiers should be
   used; implementation details can be found in the corresponding .MOD files.
*)


(* The TermOut module is used to do all terminal output. *)
FROM TermOut IMPORT
   Write, WriteString, WriteInt, WriteCard, WriteLn, Halt;


(* The Options module carries out the task of reading the DCL command
   line and extracting the DVI file parameter and qualifiers.
*)
FROM Options IMPORT
   validunits, units,
   reverse, stats, conserveVM,
   subrange, firstTeXpage, finalTeXpage, firstDVIpage, finalDVIpage,
   increment, resolution, mag, paperwd, paperht, hoffset, voffset,
   psprefix, tfmdir, fontdir, dummyfont, header, PSname, DVIname;


(* PSDVI uses the routines and data structures defined in DVIReader to move
   about randomly in the DVI file and to interpret pages.
   The reference points of characters and rules on a page are stored as
   pairs of horizontal and vertical pixel coordinates.
   The coordinate scheme is described in detail in DVIREADER.DEF.
*)
FROM DVIReader IMPORT
   ruletablesize, chartablesize, maxfontspec, maxTeXchar,
   ruleinfo, ruleinfoptr,
   fontstring, fontinfo, fontinfoptr,
   charinfo, charinfoptr, pixeltable, pixeltableptr,
   TeXcounters, TeXpageinfo,
   DVIerrorcodes, GetByteFunction,
   DVImag, totalpages, totalfonts,
   currDVIpage, currTeXpage,
   rulelist, totalrules, fontlist, currfont,
   minhp, minvp, maxhp, maxvp, pageempty,
   DVIErrorRoutine, SpecialRoutine, PixelTableRoutine,
   OpenDVIFile, SetConversionFactor, MoveToDVIPage, CurrMatchesNew,
   PixelRound, InterpretPage, SortFonts, CloseDVIFile;


(* PSDVI gets character metrics and bitmaps from font files.
   The FontReader module can handle a variety of different font formats.
   No more than one font file will be open at any given time.
*)
FROM FontReader IMPORT
   FillPixelTable, LoadBitmap,
   InitFontReader, BuildFontSpec,
   OpenFontFile, CloseFontFile;


(* The PSWriter routines are used to create an output file containing
   the appropriate PostScript code.
*)
FROM PSWriter IMPORT
   OpenOutput, OutputHeader, BeginPage, NewBitmapFont,
   OutputPage, specialstring, OutputSpecial,
   SaveVM, BeginPostScriptFont, SetPostScriptChar,
   BeginBitmapFont, SetBitmapChar, EndFont, RestoreVM,
   SetRule, EndPage, CloseOutput;


(*******************************************************************************
   GLOBAL DECLARATIONS
*)

CONST
   NULL = 0C;           (* SYSDEP: NULL terminates a string, unless full *)
   warning = 0;         (* SYSDEP: Halt parameter to set VMS $SEVERITY *)
   success = 1;         (* ditto *)
   error   = 2;         (* ditto *)

TYPE
   specialinfoptr = POINTER TO specialinfo;
   specialinfo    = RECORD
                       special : specialstring;
                       hp, vp  : INTEGER;
                       nextspecial : specialinfoptr;
                    END;

VAR
   speciallist : specialinfoptr;   (* for storing \special info *)
   specialtail : specialinfoptr;   (* tail of speciallist *)
   papertop,
   paperleft,
   paperbottom,
   paperright : INTEGER;           (* these define the edges of the paper *)
   warncount,                      (* count of problems detected *)
   pagecount : CARDINAL;           (* count of pages actually output *)
   unusedfont : fontinfoptr;       (* first unused font in sorted fontlist *)


(******************************************************************************)

PROCEDURE TopLevel;

(* Note that the implementation blocks of all imported modules have already
   been executed.  In particular, the Options module has read the DCL command
   line and initialized the DVI file parameter and qualifier values.
*)

VAR i : CARDINAL;

BEGIN
Initialize;
DVIErrorRoutine := MyDVIErrorRoutine;       (* called by DVIReader *)
OpenDVIFile(DVIname);                       (* and read DVImag etc. *)
IF mag = 0 THEN mag := DVImag END;          (* no /MAG value so use DVImag *)
SetConversionFactor(resolution,mag);        (* for DVIReader *)
SpecialRoutine    := MySpecialRoutine;      (* called by InterpretPage *)
PixelTableRoutine := MyPixelTableRoutine;   (* called by InterpretPage *)
InitFontReader;                             (* assign font-dependent routines *)
IF stats THEN ShowOptions END;
CheckPageRange;                             (* set firstDVIpage, finalDVIpage *)
IF OpenOutput(PSname) THEN
   (* DEBUG
   WriteString('Creating ');
   WriteString(PSname);
   WriteLn;
   GUBED *)
ELSE
   WriteString("Couldn't open output file: ");
   WriteString(PSname);
   WriteLn;
   Halt(error);
END;
IF LEN(header) > 0 THEN                     (* output header file first *)
   IF NOT OutputHeader(header) THEN
      WriteString("Couldn't open header file: ");
      WriteString(header);
      WriteLn;
      Halt(error);
   END;
END;
IF increment > 1 THEN                       (* finalDVIpage may need reducing *)
   WHILE (finalDVIpage - firstDVIpage) MOD increment > 0 DO
      DEC(finalDVIpage);
   END;
END;
IF reverse THEN
   MoveToDVIPage(finalDVIpage);             (* start with finalDVIpage *)
   finalDVIpage := firstDVIpage;            (* and end with firstDVIpage *)
ELSE
   MoveToDVIPage(firstDVIpage);             (* start with firstDVIpage *)
END;
LOOP
   DoPage;                                  (* do at least one page *)
   IF stats THEN ShowPageStats END;
   IF currDVIpage = finalDVIpage THEN EXIT END;
   IF reverse THEN
      MoveToDVIPage(currDVIpage - increment);
   ELSE
      MoveToDVIPage(currDVIpage + increment);
   END;
END;
IF stats THEN ShowFinalStats END;
CloseDVIFile;
CloseOutput;
IF warncount > 0 THEN
   Halt(warning);
ELSE
   Halt(success);
END;
END TopLevel;

(******************************************************************************)

PROCEDURE Initialize;

BEGIN
(* we don't bother checking for crazy resolution/paperht/paperwd values *)
(* top left corner of paper is fixed at (-1",-1") *)
papertop    := -INTEGER(resolution);
paperleft   := -INTEGER(resolution);
paperbottom := papertop  + INTEGER(paperht) - 1;
paperright  := paperleft + INTEGER(paperwd) - 1;
warncount := 0;
pagecount := 0;
speciallist := NIL;   (* for first MySpecialRoutine *)
END Initialize;

(******************************************************************************)

PROCEDURE MyDVIErrorRoutine (DVIerror : DVIerrorcodes);

(* DVIErrorRoutine for DVIReader; see DVIREADER.DEF. *)

BEGIN
CASE DVIerror OF
(* these errors are detected in OpenDVIFile; they are considered fatal *)
   DVIunopened      :
      WriteString("Couldn't open DVI file: ");
      WriteString(DVIname); WriteLn;
      Halt(error);  |
   DVIempty         :
      WriteString(DVIname);
      WriteString(' is empty!'); WriteLn;
      Halt(error);  |
   DVIbadid         :
      WriteString(DVIname);
      WriteString(' is not a valid DVI file!'); WriteLn;
      Halt(error);  |
   DVIstackoverflow :
      WriteString('Stack capacity exceeded!'); WriteLn;
      PleaseReport;
      Halt(error);  |
(* this error is detected in InterpretPage; we warn user but continue *)
   DVIbadchar       :
      WITH currfont^ DO
         WriteString('Ignoring unknown character from ');
         WriteString(fontspec); Write('!');
         WriteLn;
      END;          |
(* this error should never happen *)
   DVIcatastrophe   :
      WriteLn;
      WriteString('Something awful has happened!'); WriteLn;
      PleaseReport;
      Halt(error);
ELSE
   (* this will only happen if we've missed a DVI error *)
   WriteLn;
   WriteString('Bug in MyDVIErrorRoutine!'); WriteLn;
   PleaseReport;
   Halt(error);
END;
END MyDVIErrorRoutine;

(******************************************************************************)

PROCEDURE PleaseReport;

BEGIN
WriteString('Please tell your local TeXnician.'); WriteLn;
END PleaseReport;

(******************************************************************************)

PROCEDURE MySpecialRoutine (hpos, vpos,
                            totalbytes  : INTEGER;
                            NextDVIByte : GetByteFunction);

(* DVIReader has seen a \special command while interpreting the current page.
   It will call this routine and pass the current page position, the number
   of bytes in the command and a function to return their values one at a time.
   Instead of calling OutputSpecial directly, we have to save the necessary
   info away for later use (see DoPage).
*)

VAR i, flush : INTEGER;   temp : specialinfoptr;

BEGIN
NEW(temp);
WITH temp^ DO
   special := '';                     (* SYSDEP: fill with NULLs *)
   FOR i := 0 TO totalbytes-1 DO
      IF i <= HIGH(special) THEN
         special[i] := CHR(NextDVIByte());
      END;
   END;
   (* DVIReader demands that we read ALL the \special bytes *)
   IF totalbytes > HIGH(special) + 1 THEN
      INC(warncount);
      WriteString('\special command is too long: ');
      WriteString(special);
      WriteLn;
      WriteString('Truncating: ');
      FOR i := 1 TO totalbytes - (HIGH(special) + 1) DO
         Write(CHR(NextDVIByte()));   (* display the truncated bytes *)
      END;
      WriteLn;
   END;
   hp := hpos;
   vp := vpos;
   nextspecial := NIL;
END;
(* add new node to tail of list *)
IF speciallist = NIL THEN
   speciallist := temp;
ELSE
   specialtail^.nextspecial := temp;
END;
specialtail := temp;
END MySpecialRoutine;

(******************************************************************************)

PROCEDURE ShowDimension (pixels : INTEGER);

(* Show the given pixel dimension in terms of units. *)

VAR realdim : REAL;   fracpart : CARDINAL;

BEGIN
CASE units OF
   in : realdim := FLOAT(pixels) / FLOAT(resolution) |
   cm : realdim := FLOAT(pixels) / FLOAT(resolution) * 2.54 |
   mm : realdim := FLOAT(pixels) / FLOAT(resolution) * 25.4 |
   pc : realdim := FLOAT(pixels) / FLOAT(resolution) * 72.27 / 12.0 |
   pt : realdim := FLOAT(pixels) / FLOAT(resolution) * 72.27 |
   bp : realdim := FLOAT(pixels) / FLOAT(resolution) * 72.0 |
   px : WriteInt(pixels); WriteString('px'); RETURN;
END;
(* show realdim to an accuracy of 1 decimal place *)
IF ABS(realdim) < 0.05 THEN
   WriteString('0.0');
ELSE
   IF realdim < 0.0 THEN
      Write('-');
      realdim := ABS(realdim);
   END;
   realdim := realdim + 0.05;     (* round up to 1 decimal place *)
   WriteCard(TRUNC(realdim));     (* whole part *)
   Write('.');
   fracpart := TRUNC((realdim - FLOAT(TRUNC(realdim))) * 10.0);
   (* fracpart is now 0..9 *)
   WriteCard(fracpart);
END;
ShowUnits;
END ShowDimension;

(**********************************************************************)

PROCEDURE ShowUnits;

BEGIN
CASE units OF
   in : WriteString('in') |
   cm : WriteString('cm') |
   mm : WriteString('mm') |
   pc : WriteString('pc') |
   pt : WriteString('pt') |
   bp : WriteString('bp') |
   px : WriteString('px') |
END;
END ShowUnits;

(******************************************************************************)

PROCEDURE MyPixelTableRoutine;

(* PixelTableRoutine for DVIReader which has just allocated a new pixeltable
   for currfont^.  DVIReader calls this routine from InterpretPage only
   ONCE per font (the first time the font is used).
   We get the pixeltable information from the font file given by fontspec.
   If fontspec does not exist then dummyfont is used and fontid is undefined.
   We don't output any PostScript for non-existent fonts.
*)

VAR i, fontsizelen, firstn, lastn : CARDINAL;

BEGIN
(* Initialize currfont^.fontspec and return start and end of fontsize
   (unless psfont flag is set to TRUE).
   currfont^.fontexists may also become TRUE.
*)
BuildFontSpec(currfont,firstn,lastn);
WITH currfont^ DO
   IF OpenFontFile(fontspec) THEN
      (* only need fontid for a bitmapped font *)
      IF NOT psfont THEN
         fontid := fontname;
         fontsizelen := lastn - firstn + 1;
         IF fontnamelen + fontsizelen < maxfontspec THEN
            (* append ".fontsize" to fontid *)
            fontid[fontnamelen] := '.';
            FOR i := 1 TO fontsizelen DO
               fontid[fontnamelen + i] := fontspec[firstn + i - 1];
            END;
            IF fontnamelen + fontsizelen + 1 < maxfontspec THEN
               fontid[fontnamelen + fontsizelen + 1] := NULL;
            END;
         ELSE
            (* in the unlikely event that there is no room to append ".fontsize"
               we simply leave fontid = fontname and hope it's unique *)
            WriteString("fontname too long: "); WriteString(fontname); WriteLn;
            WriteString("Increase maxfontspec in DVIReader."); WriteLn;
         END;
         IF NOT conserveVM THEN
            NewBitmapFont(fontid);
         END;
      END;
      (* DEBUG
      WriteString('Reading font data from '); WriteString(fontspec); WriteLn;
      GUBED *)
   ELSIF OpenFontFile(dummyfont) THEN
      (* fontid is left undefined; it will not be used *)
      INC(warncount);
      WriteString("Couldn't open font file: "); WriteString(fontspec); WriteLn;
      (* use dummy font info instead *)
   ELSE
      WriteString("Couldn't open dummy font: "); WriteString(dummyfont);
      WriteLn; Halt(error);
   END;
   FillPixelTable;
   CloseFontFile;
END;
END MyPixelTableRoutine;

(******************************************************************************)

PROCEDURE ShowOptions;

(* Show DVI file name and qualifier values set in Options module. *)

BEGIN
WriteString('This is PSDVI, version 3.1');
WriteLn; WriteLn;
WriteString('DVI file          = '); WriteString(DVIname);
WriteLn;
WriteString('PostScript file   = '); WriteString(PSname);
WriteLn;
WriteString('Header file       = '); WriteString(header);
WriteLn;
WriteString('Resolution        = '); WriteCard(resolution);
WriteString(' pixels per inch');
WriteLn;
WriteString('Magnification     = '); WriteCard(mag);
IF mag <> DVImag THEN
   WriteString(' (DVI mag of '); WriteCard(DVImag);
   WriteString(' was overridden)');
ELSE
   WriteString(' (DVI mag)');
END;
WriteLn;
WriteString('TFM directory     = '); WriteString(tfmdir);
WriteLn;
WriteString('PS font prefix    = '); WriteString(psprefix);
WriteLn;
WriteString('Font directory    = '); WriteString(fontdir);
WriteLn;
WriteString('Dummy font        = '); WriteString(dummyfont);
WriteLn;
WriteString('Horizontal offset = '); ShowDimension(hoffset);
WriteLn;
WriteString('Vertical offset   = '); ShowDimension(voffset);
WriteLn;
WriteString('Paper width       = '); ShowDimension(paperwd);
WriteLn;
WriteString('Paper height      = '); ShowDimension(paperht);
WriteLn;
WriteString('Units             = '); ShowUnits;
WriteLn;
WriteString('Reverse           = ');
IF reverse THEN WriteString('true') ELSE WriteString('false') END;
WriteLn;
WriteString('Stats             = ');
IF stats THEN WriteString('true') ELSE WriteString('false') END;
WriteLn;
WriteString('Conserve VM       = ');
IF conserveVM THEN WriteString('true') ELSE WriteString('false') END;
WriteLn;
WriteString('Pages             = ');
IF subrange THEN
   IF firstDVIpage = 0 THEN
      WriteString(firstTeXpage);
   ELSE
      WriteCard(firstDVIpage);
   END;
   Write(':');
   IF finalDVIpage = 0 THEN
      WriteString(finalTeXpage);
   ELSE
      WriteCard(finalDVIpage);
   END;
ELSE
   WriteString('all pages');
END;
IF increment > 1 THEN
   WriteString(', but with an increment of ');
   WriteCard(increment);
END;
WriteLn;
WriteLn;
END ShowOptions;

(******************************************************************************)

PROCEDURE CheckPageRange;

(* If user requested a page subrange then we make sure it is valid. *)

VAR newTeXpage : TeXpageinfo;

BEGIN
IF NOT subrange THEN          (* translate all pages *)
   firstDVIpage := 1;
   finalDVIpage := totalpages;
ELSE
   IF firstDVIpage = 0 THEN   (* parse and locate firstTeXpage *)
      IF ParseTeXPage(firstTeXpage,newTeXpage) THEN
         MoveToDVIPage(1);
         (* go forwards until newTeXpage matches currTeXpage *)
         LOOP
            IF CurrMatchesNew(newTeXpage) THEN
               firstDVIpage := currDVIpage;
               EXIT;
            ELSIF currDVIpage = totalpages THEN
               WriteString('First TeX page does not exist!'); WriteLn;
               Halt(error);
            ELSE
               MoveToDVIPage(currDVIpage + 1);
            END;
         END;
      ELSE
         WriteString('Error in first TeX page!'); WriteLn;
         Halt(error);
      END;
   END;
   IF finalDVIpage = 0 THEN   (* parse and locate finalTeXpage *)
      IF ParseTeXPage(finalTeXpage,newTeXpage) THEN
         MoveToDVIPage(totalpages);
         (* go backwards until newTeXpage matches currTeXpage *)
         LOOP
            IF CurrMatchesNew(newTeXpage) THEN
               finalDVIpage := currDVIpage;
               EXIT;
            ELSIF currDVIpage = 1 THEN
               WriteString('Final TeX page does not exist!'); WriteLn;
               Halt(error);
            ELSE
               MoveToDVIPage(currDVIpage - 1);
            END;
         END;
      ELSE
         WriteString('Error in final TeX page!'); WriteLn;
         Halt(error);
      END;
   END;
   IF firstDVIpage > finalDVIpage THEN
      WriteString('First page > final page!'); WriteLn; Halt(error);
   ELSIF firstDVIpage > totalpages THEN
      WriteString('First page > total number of pages!'); WriteLn; Halt(error);
   END;
   (* allow user to give a final page > totalpages *)
   IF finalDVIpage > totalpages THEN finalDVIpage := totalpages END;
END;
END CheckPageRange;

(******************************************************************************)

PROCEDURE ParseTeXPage (VAR pagestring : ARRAY OF CHAR;
                        VAR newTeXpage : TeXpageinfo)
                       : BOOLEAN;

(* Return TRUE if TeX page specification in pagestring is valid.  If so then
   newTeXpage will contain the appropriate information for CurrMatchesNew.
   The syntax of a TeX page specification is [n{.n}] where n is any integer as
   defined by GetInteger.  Up to 10 integers may be given and are separated by
   periods, even if absent.  Trailing periods may be omitted.  Spaces before
   and after integers and periods are skipped.  The 10 positions correspond to
   the \count0, \count1, ... ,\count9 values that TeX stores with every page.
*)

VAR pos, len : CARDINAL;

BEGIN
WITH newTeXpage DO
   pos := 0;
   IF pagestring[pos] <> '[' THEN
      WriteString('[ expected!'); WriteLn;
      RETURN FALSE;
   END;
   lastvalue := 0;
   len := LEN(pagestring);
   LOOP
      INC(pos);
      present[lastvalue] := GetInteger(pagestring, len, pos, value[lastvalue]);
      (* pos now at len, space, period, non-digit or ']' *)
      WHILE (pos < len) AND (pagestring[pos] = ' ') DO
         INC(pos);                    (* skip any spaces *)
      END;
      IF pos = len THEN               (* check this first! *)
         WriteString('] expected!'); WriteLn;
         RETURN FALSE;
      END;
      IF pagestring[pos] = ']' THEN   (* end of TeX page specification *)
         EXIT;
      END;
      IF lastvalue < 9 THEN
         INC(lastvalue);
      ELSE
         WriteString("] expected after 10 integers!"); WriteLn;
         RETURN FALSE;
      END;
      IF pagestring[pos] <> '.' THEN
         WriteString('Period, integer or ] expected!'); WriteLn;
         RETURN FALSE;
      END;
   END;
   WHILE (lastvalue > 0) AND (NOT present[lastvalue]) DO
      DEC(lastvalue);
   END;
END;
RETURN TRUE;
END ParseTeXPage;

(******************************************************************************)

PROCEDURE GetInteger (VAR str  : ARRAY OF CHAR;  (* in *)
                      strlen   : CARDINAL;       (* in *)
                      VAR pos  : CARDINAL;       (* in/out *)
                      VAR n    : INTEGER         (* out *)
                     ) : BOOLEAN;

(* Extract an integer from given str starting at given pos.
   pos is also used to return the position after the integer.
   If no integer is found then set n to 0 and return FALSE (pos will only
   change if leading spaces were skipped).
   If ABS(n) > limit then set n to sign * limit.
   Valid syntax is  +{digit}  or  -{digit}  or  digit{digit}.
   Note that a + or - by itself is valid and sets n to 0.
*)

CONST limit = 2147483647;         (* 2^31 - 1 *)
      threshold = limit DIV 10;   (* nearing overflow *)

VAR   absval, last : CARDINAL;
      sign : INTEGER;
      inttoobig : BOOLEAN;

BEGIN
WHILE (pos < strlen) AND (str[pos] = ' ') DO   (* skip any spaces *)
   INC(pos);
END;
absval := 0; sign := 1; last := pos;
inttoobig := FALSE;
IF pos < strlen THEN
   IF str[pos] = '-' THEN
      sign := -1; INC(last);
   ELSIF str[pos] = '+' THEN
      INC(last);
   END;
   WHILE (last < strlen) AND
         (str[last] >= '0') AND (str[last] <= '9') DO
      IF (absval > threshold) OR ((absval = threshold) AND (str[last] > '7'))
         THEN
         inttoobig := TRUE;
      ELSE
         absval := absval * 10 + (ORD(str[last]) - ORD('0'));
      END;
      INC(last);
   END;
END;
IF pos = last THEN
   n := 0;
   RETURN FALSE;
ELSE
   pos := last;
   IF inttoobig THEN absval := limit END;
   n := sign * INTEGER(absval);
   RETURN TRUE;
END;
END GetInteger;

(******************************************************************************)

PROCEDURE DoPage;

(* Interpret the current DVI page and fill in DVIReader's data structures.
   PSWriter routines are called at appropriate times to output
   the PostScript description of the current page.
*)

BEGIN
INC(pagecount);
WriteCard(currDVIpage);         (* show the current DVI page *)
Write('/'); ShowTeXPage;        (* and TeX page *)
WriteLn;

BeginPage(currDVIpage);
InterpretPage;                  (* MyPixelTableRoutine calls NewBitmapFont *)
IF pageempty THEN
   OutputPage(currDVIpage);     (* must be called even if no chars/rules *)
   DoSpecials;
ELSE
   (* check that the page edges are within the paper edges *)
   IF (minhp < paperleft)  OR (minvp < papertop) OR
      (maxhp > paperright) OR (maxvp > paperbottom) THEN
      PageOffPaper;
   END;
   (* Sort fonts in order of increasing totalchars and
      return pointer to first unused font (for LoadFonts and DoFonts).
   *)
   SortFonts(unusedfont);
   IF NOT conserveVM THEN
      LoadFonts;
   END;
   OutputPage(currDVIpage);
   DoSpecials;
   DoFonts;
   DoRules;
END;
EndPage(currDVIpage);           (* final PostScript for current page *)
END DoPage;

(******************************************************************************)

PROCEDURE ShowTeXPage;

(* Show current TeX page counter(s). *)

VAR i, lastnonzero : CARDINAL;

BEGIN
Write('[');
lastnonzero := 9;
WHILE (lastnonzero > 0) AND (currTeXpage[lastnonzero] = 0) DO
   DEC(lastnonzero);        (* find last counter with non-zero value *)
END;
(* always show \count0 but don't show trailing 0 counters *)
FOR i := 0 TO lastnonzero DO
   WriteInt(currTeXpage[i]);
   IF i <> lastnonzero THEN
      Write('.');
   END;
END;
Write(']');
END ShowTeXPage;

(******************************************************************************)

PROCEDURE PageOffPaper;

(* One or more page edges do not fall within the paper edges.
   We show user just how bad the problem is.
*)

BEGIN
INC(warncount);
WriteString('Page off paper (paper is ');
ShowDimension(paperwd); WriteString(' wide by ');
ShowDimension(paperht); WriteString(' high)');
WriteLn;
IF minhp < paperleft THEN
   WriteString('Beyond left edge by ');
   ShowDimension(paperleft - minhp);
   WriteLn;
END;
IF maxhp > paperright THEN
   WriteString('Beyond right edge by ');
   ShowDimension(maxhp - paperright);
   WriteLn;
END;
IF minvp < papertop THEN
   WriteString('Above top edge by ');
   ShowDimension(papertop - minvp);
   WriteLn;
END;
IF maxvp > paperbottom THEN
   WriteString('Below bottom edge by ');
   ShowDimension(maxvp - paperbottom);
   WriteLn;
END;
END PageOffPaper;

(******************************************************************************)

PROCEDURE LoadFonts;

(* For each bitmapped font that is used (and exists) on the current page,
   go thru charlist and call LoadBitmap for each character that hasn't yet
   been downloaded.  BeginBitmapFont will only be called if necessary.
*)

VAR
   thisfontinfo : fontinfoptr;    (* current font info in fontlist *)
   thischarinfo : charinfoptr;    (* current char info in charlist *)
   thischar     : CARDINAL;       (* current index into current chartable *)
   fontopen     : BOOLEAN;        (* is thisfontinfo^.fontspec open? *)

BEGIN
thisfontinfo := fontlist;
WHILE thisfontinfo <> unusedfont DO
(* SortFonts makes sure we only consider used fonts *)
WITH thisfontinfo^ DO
   (* do nothing if resident PostScript font or bitmapped font doesn't exist *)
   IF (NOT psfont) AND fontexists THEN
      fontopen := FALSE;              (* avoid opening font unnecessarily *)
      thischarinfo := charlist;
      WHILE thischarinfo <> NIL DO    (* process unloaded chars in chartable *)
         WITH thischarinfo^ DO
            thischar := 0;
            WHILE thischar < charcount DO
               WITH chartable[thischar] DO
               WITH pixelptr^[code] DO
                  IF (NOT loaded) AND (mapadr > 0) THEN   (* load bitmap *)
                     IF NOT fontopen THEN
                        OpenFont(thisfontinfo);
                        BeginBitmapFont(fontid);
                        fontopen := TRUE;                 (* only open once *)
                     END;
                     LoadBitmap(thisfontinfo,code);
                     loaded := TRUE;                      (* only load once *)
                  END;
               END;
               END;
               INC(thischar);
            END;
            thischarinfo := nextchar;
         END;
      END;
      IF fontopen THEN CloseFontFile END;
   END;
   thisfontinfo := nextfont;
END; (* WITH *)
END; (* WHILE *)
END LoadFonts;

(******************************************************************************)

PROCEDURE OpenFont (thisfontinfo : fontinfoptr);

BEGIN
WITH thisfontinfo^ DO
   IF OpenFontFile(fontspec) THEN
      (* DEBUG
      WriteString("Loading characters for ");
      WriteString(fontspec);
      WriteLn;
      GUBED *)
   ELSE
      (* this should never happen since we avoid loading dummy font chars *)
      WriteLn;
      WriteString('Bug in OpenFont!  Could not open: ');
      WriteString(fontspec);
      WriteLn; Halt(error);
   END;
END;
END OpenFont;

(******************************************************************************)

PROCEDURE DoSpecials;

(* Call OutputSpecial for each \special command on the current page.
   (The speciallist is built by MySpecialRoutine during InterpretPage.)
*)

VAR temp : specialinfoptr;

BEGIN
WHILE speciallist <> NIL DO
   WITH speciallist^ DO
      (* The \special bytes are treated as a file name, possibly followed by
         a space and additional PostScript text.
         PSWriter will read this file and copy it verbatim to the output file.
         The optional text is prefixed to the file as a separate line.
      *)
      IF NOT OutputSpecial(special,hp,vp) THEN
         INC(warncount);
         WriteString("Couldn't open \special file: ");
         WriteString(special);   (* includes optional text *)
         WriteLn;
      ELSIF stats THEN
         WriteString('\special command at (');
         ShowDimension(hp); Write(',');
         ShowDimension(vp); WriteString('): ');
         WriteString(special); WriteLn;
      END;
      temp := speciallist;
      speciallist := nextspecial;
      DISPOSE(temp);   (* speciallist must be NIL for next page *)
   END;
END;
END DoSpecials;

(******************************************************************************)

PROCEDURE DoFonts;

(* For each font that is used (and exists) on the current page,
   call the appropriate sequence of PSWriter routines depending on
   the conserveVM flag and whether the font is bitmapped or resident.
   See PSWRITER.DEF for details.
*)

VAR
   thisfontinfo : fontinfoptr;    (* current font info in fontlist *)
   thischarinfo : charinfoptr;    (* current char info in charlist *)
   thischar     : CARDINAL;       (* current index into current chartable *)

BEGIN
thisfontinfo := fontlist;
WHILE thisfontinfo <> unusedfont DO
(* SortFonts makes sure we only consider used fonts! *)
WITH thisfontinfo^ DO
   IF fontexists THEN                          (* won't be dummy font info *)
      IF psfont THEN
         BeginPostScriptFont(fontname,scaledsize,mag);
      ELSE
         IF conserveVM THEN SaveVM(fontid) END;
         BeginBitmapFont(fontid);
      END;

      IF conserveVM AND (NOT psfont) THEN      (* download bitmaps *)
         OpenFont(thisfontinfo);
         thischarinfo := charlist;
         WHILE thischarinfo <> NIL DO          (* process unique chars *)
            WITH thischarinfo^ DO
               thischar := 0;
               WHILE thischar < charcount DO
                  WITH chartable[thischar] DO
                  WITH pixelptr^[code] DO
                     IF (NOT loaded) AND (mapadr > 0) THEN   (* load bitmap *)
                        LoadBitmap(thisfontinfo,code);
                        loaded := TRUE;                      (* but only once *)
                     END;
                  END;
                  END;
                  INC(thischar);
               END;
               thischarinfo := nextchar;
            END;
         END;
         CloseFontFile;
         (* reset loaded flags to FALSE for next page *)
         FOR thischar := 0 TO maxTeXchar DO
            pixelptr^[thischar].loaded := FALSE;
         END;
      END;

      IF psfont THEN
         thischarinfo := charlist;
         WHILE thischarinfo <> NIL DO
            WITH thischarinfo^ DO
               thischar := 0;
               WHILE thischar < charcount DO
                  WITH chartable[thischar] DO
                  WITH pixelptr^[code] DO
                     IF mapadr > 0 THEN               (* char exists *)
                        SetPostScriptChar(CHR(code),
                                          hp,vp,      (* reference point *)
                                          pwidth);    (* advance width *)
                     END;
                  END;
                  END;
                  INC(thischar);
               END;
               thischarinfo := nextchar;
            END;
         END;
      ELSE
         thischarinfo := charlist;
         WHILE thischarinfo <> NIL DO
            WITH thischarinfo^ DO
               thischar := 0;
               WHILE thischar < charcount DO
                  WITH chartable[thischar] DO
                  WITH pixelptr^[code] DO
                     IF mapadr > 0 THEN               (* char exists *)
                        SetBitmapChar(CHR(code),
                                      hp,vp,          (* reference point *)
                                      pwidth);        (* advance width *)
                     END;
                  END;
                  END;
                  INC(thischar);
               END;
               thischarinfo := nextchar;
            END;
         END;
      END;
      EndFont;

      IF conserveVM AND (NOT psfont) THEN RestoreVM END;
   END;
   thisfontinfo := nextfont;
END; (* WITH *)
END; (* WHILE *)
END DoFonts;

(******************************************************************************)

PROCEDURE DoRules;

(* Call SetRule for each rule on the current page. *)

VAR thisrule : CARDINAL;
    thisruleinfo : ruleinfoptr;

BEGIN
thisruleinfo := rulelist;
WHILE thisruleinfo <> NIL DO
   WITH thisruleinfo^ DO
      thisrule := 0;
      WHILE thisrule < rulecount DO
         WITH ruletable[thisrule] DO
            SetRule(wd,ht,    (* width and height of rule *)
                    hp,vp);   (* bottom left corner of rule *)
         END;
         INC(thisrule);
      END;
      thisruleinfo := nextrule;
   END;
END;
END DoRules;

(******************************************************************************)

PROCEDURE ShowPageStats;

(* Show rule/font/character statistics for current page. *)

VAR fontcount : CARDINAL;
    thisfontinfo : fontinfoptr;

BEGIN
WriteString('Total rules on current page = '); WriteCard(totalrules);
WriteLn;
WriteString('Fonts on current page:');
WriteLn;
fontcount := 0;
thisfontinfo := fontlist;
WHILE thisfontinfo <> NIL DO
   WITH thisfontinfo^ DO
      IF fontused THEN
         WriteString(fontspec);
         IF psfont THEN ShowPtSize(scaledsize) END;
         IF NOT fontexists THEN WriteString('   DOES NOT EXIST!') END;
         INC(fontcount);
         WriteString('   total chars = '); WriteCard(totalchars); WriteLn;
      END;
      thisfontinfo := nextfont;
   END;
END;
WriteString('Total fonts on current page = '); WriteCard(fontcount);
WriteLn;
WriteLn;
END ShowPageStats;

(******************************************************************************)

PROCEDURE ShowFinalStats;

(* Show some overall statistics. *)

VAR fontsused, c, loadcount, loadtotal, bitmapbytes : CARDINAL;
    thisfontinfo : fontinfoptr;

BEGIN
WriteString('Summary'); WriteLn;
WriteString('======='); WriteLn;
WriteLn;
WriteString('Total pages output = '); WriteCard(pagecount);
WriteLn;
WriteString('Total pages in DVI file = '); WriteCard(totalpages);
WriteLn;
WriteString('Total fonts in DVI file = '); WriteCard(totalfonts);
WriteLn;
(* go thru fontlist showing info for EVERY font *)
fontsused := 0;
loadtotal := 0;
bitmapbytes := 0;
thisfontinfo := fontlist;
WHILE thisfontinfo <> NIL DO
   WITH thisfontinfo^ DO
      IF fontspeclen > 0 THEN
         WriteString(fontspec);
         IF psfont THEN ShowPtSize(scaledsize) END;
         IF fontexists THEN
            INC(fontsused);
            IF (NOT conserveVM) AND (NOT psfont) THEN
               loadcount := 0;
               FOR c := 0 TO maxTeXchar DO
                  WITH pixelptr^[c] DO
                     IF loaded AND (mapadr > 0) THEN
                        INC(loadcount);
                        INC(bitmapbytes, ht * ((wd + 7) DIV 8) );
                     END;
                  END;
               END;
               WriteString('   loaded chars = '); WriteCard(loadcount);
               INC(loadtotal,loadcount);
            END;
         ELSE
            WriteString('   DOES NOT EXIST!');
         END;
      ELSE
         WriteString(fontname);
         WriteString(' scaled ');
         WriteCard(TRUNC( FLOAT(mag) *
                          FLOAT(scaledsize)/FLOAT(designsize) + 0.5 ));
         WriteString(' not used');
      END;
      WriteLn;
      thisfontinfo := nextfont;
   END;
END;
WriteString('Total fonts actually used = '); WriteCard(fontsused);
WriteLn;
IF NOT conserveVM THEN
   WriteString('Total characters loaded = '); WriteCard(loadtotal);
   WriteLn;
   WriteString('Hex digits in loaded bitmaps = 2 * '); WriteCard(bitmapbytes);
   WriteLn;
END;
END ShowFinalStats;

(******************************************************************************)

PROCEDURE ShowPtSize (scaledsize : INTEGER);

(* Show given font size (in DVI units) in terms of (possibly magnified) pts. *)

VAR realdim : REAL;   fracpart : CARDINAL;

BEGIN
WriteString(' at ');
realdim := (FLOAT(scaledsize) / FLOAT(10000H)) * (FLOAT(mag) / 1000.0);
(* show realdim to an accuracy of 1 decimal place *)
IF ABS(realdim) < 0.05 THEN
   WriteString('0');
ELSE
   IF realdim < 0.0 THEN
      Write('-');
      realdim := ABS(realdim);
   END;
   realdim := realdim + 0.05;     (* round up to 1 decimal place *)
   WriteCard(TRUNC(realdim));     (* whole part *)
   fracpart := TRUNC((realdim - FLOAT(TRUNC(realdim))) * 10.0);   (* 0..9 *)
   IF fracpart > 0 THEN
      Write('.');
      WriteCard(fracpart);
   END;
END;
WriteString('pt');
END ShowPtSize;

(******************************************************************************)

BEGIN
TopLevel;
END PSDVI.