/* Copyright (c) 1987, 1989, 2012 University of Maryland Department of
   Computer Science.
   
   Permission is hereby granted, free of charge, to any person obtaining
   a copy of this software and associated documentation files (the
   "Software"), to deal in the Software without restriction, including
   without limitation, the rights to use, copy, modify, merge, publish,
   distribute, sublicense, and/or sell copies of the Software, and to
   permit persons to whom the Software is furnished to do so, subject to
   the following conditions: The above copyright notice, this permission
   notice and the disclaimer statement shall be included in all copies
   or substantial portions of the Software.
   
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
   CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
   TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

/*
 * DVI page selection program
 *
 * Reads DVI version 2 files and selects pages, writing a new DVI
 * file.  The new DVI file is technically correct, though we do not
 * adjust the tallest and widest page values, nor the DVI stack size.
 * This is all right since the values will never become too small,
 * but it might be nice to fix them up.  Perhaps someday . . . .
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
 
#ifdef KPATHSEA
#include <kpathsea/config.h>
#include <kpathsea/c-fopen.h>
#include <kpathsea/getopt.h>
#if defined(WIN32)
#include <kpathsea/variable.h>
#endif
#else
#define FOPEN_RBIN_MODE  "rb"
#define FOPEN_WBIN_MODE  "wb"
#define SET_BINARY(x) (void)0
extern char *optarg;
extern int optind;
#endif
 
#include "types.h"
#include "dviclass.h"
#include "dvicodes.h"
#include "error.h"
#include "fio.h"
#include "gripes.h"
#include "search.h"
#include <stdio.h>
#include <ctype.h>
#include "common.h"

#define white(x) ((x) == ' ' || (x) == '\t' || (x) == ',')

char  *ProgName;
/* Globals */
char	serrbuf[BUFSIZ];	/* buffer for stderr */

/*
 * We will try to keep output lines shorter than MAXCOL characters.
 */
#define MAXCOL	75

/*
 * We use the following structure to keep track of fonts we have seen.
 * The final DVI file lists only the fonts it uses.
 */
struct fontinfo {
	i32	fi_newindex;	/* font number in output file */
	int	fi_reallyused;	/* true => used on a page we copied */
	i32	fi_checksum;	/* the checksum */
	i32	fi_mag;		/* the magnification */
	i32	fi_designsize;	/* the design size */
	short	fi_n1;		/* the name header length */
	short	fi_n2;		/* the name body length */
	char	*fi_name;	/* the name itself */
};

/*
 * We need to remember which pages the user would like.  We build a linked
 * list that allows us to decide (for any given page) whether it should
 * be included in the output file.  Each page has ten \count variables
 * associated with it.  We put a bound on the values allowed for each, and
 * keep a linked list of alternatives should any be outside the allowed
 * range.  For example, `dviselect *.3,10-15' would generate a two-element
 * page list, with the first allowing any value for \count0 (and \counts 2 to
 * 9) but \count1 restricted to the range 3-3, and the second restricting
 * \count0 to the range 10-15 but leaving \counts 1 to 9 unrestrained.
 *
 * We remember whether a bound is specified, so that we need not fix
 * some `large' number as a maximum value.
 *
 * We also allow `absolute' page references, where the first page is
 * page 1, the second 2, and so forth.  These are specified with an
 * equal sign: `dviselect =4:10' picks up the fourth through tenth
 * sequential pages, irrespective of \count values.
 *
 * There is also an even/odd switch (which can be applied to absolute
 * or relative pages): dviselect =even, even.3, etc.
 */
enum pstype {
	pt_lu,			/* have both lower and upper bounds */
	pt_l,			/* lower bound only */
	pt_u,			/* upper bound only */
	pt_unbounded,		/* any value at all */
	pt_even,		/* even values only */
	pt_odd			/* odd values only */
};
struct pagesel {
	enum pstype ps_type;	/* type of selector */
	i32	ps_low;		/* lower bound */
	i32	ps_high;	/* upper bound */
};
struct pagelist {
	struct	pagelist *pl_alt;	/* next in a series of alternates */
	int	pl_len;			/* number of ranges to check */
	int	pl_abs;			/* true iff absolute page ref */
	struct	pagesel pl_pages[10];	/* one for each \count variable */
};

int	SFlag;			/* true => -s, silent operation */

struct	search *FontFinder;	/* maps from input indicies to fontinfo */
i32	NextOutputFontIndex;	/* generates output indicies */
i32	CurrentFontIndex;	/* current (old) index in input */
i32	OutputFontIndex;	/* current (new) index in ouput */

struct	pagelist *PageList;	/* the list of allowed pages */

const char	*DVIFileName;	/* name of input DVI file */
FILE		*inf;		/* the input file itself */
const char	*outname;	/* name of output DVI file */
FILE		*outf;		/* the output DVI file */

long	StartOfLastPage;	/* The file position just before we started
				   the last page (this is later written to
				   the output file as the previous page
				   pointer). */
long	CurrentPosition;	/* The current position of the file */

int	UseThisPage;		/* true => current page is selected */
#ifdef ASCIIPTEX
int	ptexdvi;		/* true => dvi format is extended (TATEKUMI) */
#endif /* ASCIIPTEX */

i32	InputPageNumber;	/* current absolute page in old DVI file */
int	NumberOfOutputPages;	/* number of pages in new DVI file */

i32	Numerator;		/* numerator from DVI file */
i32	Denominator;		/* denominator from DVI file */
i32	DVIMag;			/* magnification from DVI file */

i32	Count[10];		/* the 10 \count variables */

/* save some string space: we use this a lot */
char	writeerr[] = "error writing DVI file";

#include <string.h>
static void WriteFont(struct fontinfo *);
static int evenodd(char *);
static int ParsePages(char *);
static void HandleDVIFile(void);
static void PutFontSelector(i32);
static void WritePreAmble(void);

#ifndef KPATHSEA
char	*malloc(), *realloc();
#endif /* not KPATHSEA */

/*
 * You may get lint warnings about sprintf's return value.
 * Older versions of 4BSD have `char *sprintf()'.  ANSI and
 * SysV use `int sprintf()'; so ignore the warnings.
 */

/*
 * Lint gets somewhat confused over putc.
 */
#ifdef lint
#undef putc
#ifdef ultrix /* grr */
#define putc(c, f) fputc((char)(c), f)
#else
#define putc(c, f) fputc((int)(c), f)
#endif
#endif

/*
 * Return true iff the 10 \counts are one of the desired output pages.
 */
static int
DesiredPageP(void)
{
	register struct pagelist *pl;

	for (pl = PageList; pl != NULL; pl = pl->pl_alt) {
		register struct pagesel *ps = pl->pl_pages;
		register int i;
		register i32 *pagep;

		pagep = pl->pl_abs ? &InputPageNumber : &Count[0];
		for (i = 0; i < pl->pl_len; i++, ps++, pagep++) {
			switch (ps->ps_type) {

			case pt_lu:	/* check upper, fall through */
				if (*pagep > ps->ps_high)
					goto no_good;
				/* FALLTHROUGH */

			case pt_l:	/* only if not too low */
				if (*pagep < ps->ps_low)
					goto no_good;
				break;

			case pt_u:	/* only if not too high */
				if (*pagep > ps->ps_high)
					goto no_good;
				break;

			case pt_unbounded:
				break;

			case pt_even:	/* only if even */
				if (*pagep & 1)
					goto no_good;
				break;

			case pt_odd:	/* only if odd */
				if ((*pagep & 1) == 0)
					goto no_good;
				break;
			}
		}
		return (1);	/* success */
	no_good:
		continue;
	}
	return (0);
}

/*
 * Print a message to stderr, with an optional leading space, and handling
 * long line wraps.
 */
static void
message(int space, const char *str, int len)
{
	static int beenhere;
	static int col;

	if (!beenhere)
		space = 0, beenhere++;
	if (len == 0)
		len = strlen(str);
	col += len;
	if (space) {
		if (col >= MAXCOL)
			(void) putc('\n', stderr), col = len;
		else
			(void) putc(' ', stderr), col++;
	}
	while (--len >= 0)
		(void) putc(*str++, stderr);
	(void) fflush(stderr);
}

/*
 * Start a page (process a DVI_BOP).
 */
static void
BeginPage(void)
{
	register i32 *i;

	OutputFontIndex = -1;	/* new page requires respecifying font */
	InputPageNumber++;	/* count it */
	for (i = Count; i < &Count[10]; i++)
		fGetLong(inf, *i);
	(void) GetLong(inf);	/* previous page pointer */

	if ((UseThisPage = DesiredPageP()) == 0)
		return;

	if (NumberOfOutputPages == 0)
		WritePreAmble();

	putbyte(outf, DVI_BOP);
	for (i = Count; i < &Count[10]; i++)
		PutLong(outf, *i);
	PutLong(outf, StartOfLastPage);
	if (ferror(outf))
		error(1, -1, writeerr);

	StartOfLastPage = CurrentPosition;
	CurrentPosition += 45;	/* we just wrote this much */

	if (!SFlag) {		/* write nice page usage messages */
		register int z = 0;
		register int mlen = 0;
		char msg[80];

		(void) sprintf(msg, "[%ld", (long)Count[0]);
		mlen = strlen(msg);
		for (i = &Count[1]; i < &Count[10]; i++) {
			if (*i == 0) {
				z++;
				continue;
			}
			while (--z >= 0)
				msg[mlen++] = '.', msg[mlen++] = '0';
			z = 0;
			(void) sprintf(msg + mlen, ".%ld", (long)*i);
			mlen += strlen(msg + mlen);
		}
		message(1, msg, mlen);
	}
}

/*
 * End a page (process a DVI_EOP).
 */
static void
EndPage(void)
{

	if (!UseThisPage)
		return;
	if (!SFlag)
		message(0, "]", 1);
	putbyte(outf, DVI_EOP);
	if (ferror(outf))
		error(1, -1, writeerr);
	CurrentPosition++;
	NumberOfOutputPages++;
}

/*
 * For each of the fonts used in the new DVI file, write out a definition.
 */
/* ARGSUSED */
static void
PostAmbleFontEnumerator(char *addr, i32 key)
{

	if (((struct fontinfo *)addr)->fi_reallyused)
		WriteFont((struct fontinfo *)addr);
}

static void
HandlePostAmble(void)
{
	register i32 c;

	if (NumberOfOutputPages == 0)
		return;

	(void) GetLong(inf);	/* previous page pointer */
	if (GetLong(inf) != Numerator)
		GripeMismatchedValue("numerator");
	if (GetLong(inf) != Denominator)
		GripeMismatchedValue("denominator");
	if (GetLong(inf) != DVIMag)
		GripeMismatchedValue("\\magnification");

	putbyte(outf, DVI_POST);
	PutLong(outf, StartOfLastPage);
	PutLong(outf, Numerator);
	PutLong(outf, Denominator);
	PutLong(outf, DVIMag);
	c = GetLong(inf);
	PutLong(outf, c);	/* tallest page height */
	c = GetLong(inf);
	PutLong(outf, c);	/* widest page width */
	c = GetWord(inf);
	PutWord(outf, c);	/* DVI stack size */
	PutWord(outf, NumberOfOutputPages);
	StartOfLastPage = CurrentPosition;	/* point at post */
	CurrentPosition += 29;	/* count all those `put's */
#ifdef notdef
	(void) GetWord(inf);	/* skip original number of pages */
#endif

	/*
	 * just ignore all the incoming font definitions; we are done with
	 * input file 
	 */

	/*
	 * run through the FontFinder table and dump definitions for the
	 * fonts we have used. 
	 */
	SEnumerate(FontFinder, PostAmbleFontEnumerator);

	putbyte(outf, DVI_POSTPOST);
	PutLong(outf, StartOfLastPage);	/* actually start of postamble */
#ifdef ASCIIPTEX
	if (ptexdvi)
	  putbyte(outf, DVI_PTEXVERSION);
	else
#endif /* ASCIIPTEX */
	putbyte(outf, DVI_VERSION);
	putbyte(outf, DVI_FILLER);
	putbyte(outf, DVI_FILLER);
	putbyte(outf, DVI_FILLER);
	putbyte(outf, DVI_FILLER);
	CurrentPosition += 10;
	while (CurrentPosition & 3) {
		putbyte(outf, DVI_FILLER);
		CurrentPosition++;
	}
	if (ferror(outf))
		error(1, -1, writeerr);
}

/*
 * Write a font definition to the output file
 */
static void
WriteFont(struct fontinfo *fi)
{
	register int l;
	register char *s;

	if (fi->fi_newindex < 256) {
		putbyte(outf, DVI_FNTDEF1);
		putbyte(outf, fi->fi_newindex);
		CurrentPosition += 2;
	} else if (fi->fi_newindex < 65536) {
		putbyte(outf, DVI_FNTDEF2);
		PutWord(outf, fi->fi_newindex);
		CurrentPosition += 3;
	} else if (fi->fi_newindex < 16777216) {
		putbyte(outf, DVI_FNTDEF3);
		Put3Byte(outf, fi->fi_newindex);
		CurrentPosition += 4;
	} else {
		putbyte(outf, DVI_FNTDEF4);
		PutLong(outf, fi->fi_newindex);
		CurrentPosition += 5;
	}
	PutLong(outf, fi->fi_checksum);
	PutLong(outf, fi->fi_mag);
	PutLong(outf, fi->fi_designsize);
	putbyte(outf, fi->fi_n1);
	putbyte(outf, fi->fi_n2);
	l = fi->fi_n1 + fi->fi_n2;
	CurrentPosition += 14 + l;
	s = fi->fi_name;
	while (--l >= 0)
		putbyte(outf, *s++);
}

/*
 * Array to hold the preamble comment.
 */
static char PreComment[256];

/*
 * Read the preamble.  Someday we should update the comment field.
 */
static void
ReadPreAmble(void)
{
	register int n, c;
	char *comment = PreComment;

	c = getc(inf);
	if (c == EOF)
		GripeUnexpectedDVIEOF();
	if (c != DVI_PRE)
		GripeMissingOp("PRE");
	if (getc(inf) != DVI_VERSION)
		error(1, 0, "%s is not a DVI version %d file",
		    DVIFileName, DVI_VERSION);
	Numerator = GetLong(inf);
	Denominator = GetLong(inf);
	DVIMag = GetLong(inf);
	c = GetByte(inf);
	n = UnSign8(c);
	*comment++ = (char)c;
	while (--n >= 0) {
		c = GetByte(inf);
		*comment++ = (char)c;
	}
}

/*
 * Open the output and write the preamble.
 */
static void
WritePreAmble(void)
{
	register int n, c;
	char *comment = PreComment;

	if (outname == NULL) {
		outf = stdout;
		if (!isatty(fileno(outf)))
		  SET_BINARY(fileno(outf));
	} else if ((outf = fopen(outname, FOPEN_WBIN_MODE)) == 0)
		error(1, -1, "cannot write %s", outname);

	putbyte(outf, DVI_PRE);
	putbyte(outf, DVI_VERSION);
	PutLong(outf, Numerator);
	PutLong(outf, Denominator);
	PutLong(outf, DVIMag);

	c = *comment++;
	n = UnSign8(c);
	CurrentPosition = 15 + n;	/* well, almost */
	putbyte(outf, n);
	while (--n >= 0) {
		c = *comment++;
		putbyte(outf, c);
	}
}

int
main(int argc, char **argv)
{
	register int c;
	register char *s;
#if defined(WIN32) && defined(KPATHSEA)
	int ac;
	char **av, *enc;

	if (argc>1) {
		kpse_set_program_name(argv[0], "dviselect");
		enc = kpse_var_value("command_line_encoding");
		if (get_command_line_args_utf8(enc, &ac, &av)) {
			argc = ac;
			argv = av;
		}
	}
#endif

	ProgName = *argv;
	setbuf(stderr, serrbuf);

	while ((c = getopt(argc, argv, "i:o:s")) != EOF) {
		switch (c) {

		case 's':	/* silent */
			SFlag++;
			break;

		case 'i':
			if (DVIFileName != NULL)
				goto usage;
			DVIFileName = optarg;
			break;

		case 'o':
			if (outname != NULL)
				goto usage;
			outname = optarg;
			break;

		case '?':
usage:
			(void) fprintf(stderr,
				"dviselect  in SeeTeX Ver.%s (%s)\n", VERSION, TL_VERSION);
			(void) fprintf(stderr, "\
Usage: %s [-s] [-i infile] [-o outfile] pages [...] [infile [outfile]]\n",
				ProgName);
			(void) fprintf(stderr,
				"\nEmail bug reports to %s.\n", BUG_ADDRESS);
			(void) fflush(stderr);
			exit(1);
		}
	}

	while (optind < argc) {
		s = argv[optind++];
		c = *s;
		if (!(isalpha(c) || 
		      c == '/' ||
		      (c == '.' && (s[1] == '/' || (s[1] == '.' && s[2] == '/')))) ||
		    ((c == 'e' || c == 'o') && evenodd(s))) {
			if (ParsePages(s))
				goto usage;
		} else if (DVIFileName == NULL)
			DVIFileName = s;
		else if (outname == NULL)
			outname = s;
		else
			goto usage;
	}
	if (PageList == NULL)
		goto usage;
	if (DVIFileName == NULL) {
		DVIFileName = "`stdin'";
		inf = stdin;
		if (!isatty(fileno(inf)))
		  SET_BINARY(fileno(inf));
		else
		  goto usage;
	} else if ((inf = fopen(DVIFileName, FOPEN_RBIN_MODE)) == 0)
		error(1, -1, "cannot read %s", DVIFileName);

	if ((FontFinder = SCreate(sizeof(struct fontinfo))) == 0)
		error(1, 0, "cannot create font finder (out of memory?)");

	StartOfLastPage = -1;
	ReadPreAmble();
#ifdef ASCIIPTEX
	ptexdvi = 0;
#endif /* ASCIIPTEX */
	HandleDVIFile();
	HandlePostAmble();
	if (NumberOfOutputPages > 0) {
		if (!SFlag)
			(void) fprintf(stderr, "\nWrote %d page%s, %ld bytes\n",
			    NumberOfOutputPages, NumberOfOutputPages == 1 ? "" : "s",
 			    (long)CurrentPosition);
		return 0;
	} else {
		if (!SFlag)
			(void) fprintf(stderr, "Specified page may be out of range\n");
		return 1;
	}
}

static struct pagelist *
InstallPL(struct pagesel *ps, int n, int absolute)
{
	register struct pagelist *pl;

	pl = (struct pagelist *)malloc(sizeof *pl);
	if (pl == NULL)
		GripeOutOfMemory(sizeof *pl, "page list");
	pl->pl_alt = PageList;
	PageList = pl;
	pl->pl_len = n;
	while (--n >= 0)
		pl->pl_pages[n] = ps[n];
	pl->pl_abs = absolute;
	return pl;
}

/*
 * Return true iff the string `s' is the word `even' or `odd',
 * followed by `.' or `white' characters.
 */
static int
evenodd(char *s)
{
	register int c;

	if (strncmp(s, "even", 4) == 0)
		c = s[4];
	else if (strncmp(s, "odd", 3) == 0)
		c = s[3];
	else
		return (0);
	if (c == 0 || c == '.' || white(c))
		return (1);
	return (0);
}

/*
 * Parse a string representing a list of pages.  Return 0 iff ok.  As a
 * side effect, the page selection(s) is (are) prepended to PageList.
 */
static int
ParsePages(char *s)
{
	register struct pagesel *ps;
	register int c;		/* current character */
	register i32 n;		/* current numeric value */
	register int innumber;	/* true => gathering a number */
	int i;			/* next index in page select list */
	int range;		/* true => saw a range indicator */
	int negative;		/* true => number being built is negative */
	int absolute;		/* true => absolute, not \count */
	int lb, ub, even, odd;	/* flags for lower,upper,even,odd */
	struct pagesel pagesel[10];

	range = 0;
	n = 0;
	innumber = 0;
	negative = 0;
	absolute = 0;
	i = 0;
	ps = pagesel;
	lb = ub = even = odd = 0;
	/*
	 * Talk about ad hoc!  (Not to mention convoluted.)
	 */
	for (;;) {
		c = *s++;
		if (i == 0 && !innumber && !range) {
			/* nothing special going on */
			if (c == 0)
				return 0;
			if (white(c))
				continue;
		}
		if ((c == 'e' || c == 'o') && evenodd(s - 1)) {
			if (innumber || range)
				return (-1);
			if (c == 'e') {
				s += 3;
				even = 1;
			} else {
				s += 2;
				odd = 1;
			}
			c = *s++;
			goto finishnum;
		}
		if (c == '_') {
			/* kludge: should be '-' for negatives */
			if (innumber || absolute)
				return (-1);
			innumber = 1;
			negative = 1;
			n = 0;
			continue;
		}
		if (c == '=') {
			/* absolute page */
			if (innumber || range || i > 0)
				return (-1);
			absolute = 1;
			negative = 0;
			n = 0;
			continue;
		}
		if (isdigit(c)) {
			/* accumulate numeric value */
			if (!innumber) {
				innumber = 1;
				negative = 0;
				n = c - '0';
				continue;
			}
			n *= 10;
			n += negative ? '0' - c : c - '0';
			continue;
		}
		if (c == '-' || c == ':') {
			/* here is a range */
			if (range)
				return (-1);
			if (innumber) {	/* have a lower bound */
				ps->ps_low = n;
				lb = 1;
			}
			range = 1;
			innumber = 0;
			continue;
		}
		if (c == '*') {
			/* no lower bound, no upper bound */
			c = *s++;
			if (innumber || range || (c && c != '.' && !white(c)))
				return (-1);
			goto finishnum;
		}
		if (c == 0 || c == '.' || white(c)) {
			/* end of this range */
			if (innumber) {		/* have an upper bound */
				ps->ps_high = n;
				ub = 1;
				if (!range) {
					/* no range => lower bound == upper */
					ps->ps_low = ps->ps_high;
					lb = 1;
				}
			}
finishnum:
			if (even)
				ps->ps_type = pt_even;
			else if (odd)
				ps->ps_type = pt_odd;
			else if (lb)
				ps->ps_type = ub ? pt_lu : pt_l;
			else
				ps->ps_type = ub ? pt_u : pt_unbounded;
			if (c == '.') {
				if (absolute)
					return (-1);
				if (++i >= 10)	/* too many specifiers */
					return (-1);
				ps++;
			} else {
				InstallPL(pagesel, i + 1, absolute);
				ps = pagesel;
				i = 0;
				absolute = 0;
			}
			if (c == 0)
				return (0);
			range = 0;
			innumber = 0;
			lb = ub = even = odd = 0;
			continue;
		}
		/* illegal character */
		return (-1);
	}
}

/*
 * Handle a font definition.
 */
static void
HandleFontDef(i32 index)
{
	register struct fontinfo *fi;
	register int i;
	register char *s;
	int def = S_CREATE | S_EXCL;

	if ((fi = (struct fontinfo *)SSearch(FontFinder, index, &def)) == 0) {
		if (def & S_COLL)
			error(1, 0, "font %ld already defined", (long)index);
		else
			error(1, 0, "cannot stash font %ld (out of memory?)",
				(long)index);
	}
	fi->fi_reallyused = 0;
	fi->fi_checksum = GetLong(inf);
	fi->fi_mag = GetLong(inf);
	fi->fi_designsize = GetLong(inf);
	fi->fi_n1 = UnSign8(GetByte(inf));
	fi->fi_n2 = UnSign8(GetByte(inf));
	i = fi->fi_n1 + fi->fi_n2;
	if ((s = malloc((unsigned)i)) == 0)
		GripeOutOfMemory(i, "font name");
	fi->fi_name = s;
	while (--i >= 0)
		*s++ = GetByte(inf);
}

/*
 * Handle a \special.
 */
static void
HandleSpecial(int c, int l, i32 p)
{
	register int i;

	if (UseThisPage) {
		putbyte(outf, c);
		switch (l) {

		case DPL_UNS1:
			putbyte(outf, p);
			CurrentPosition += 2;
			break;

		case DPL_UNS2:
			PutWord(outf, p);
			CurrentPosition += 3;
			break;

		case DPL_UNS3:
			Put3Byte(outf, p);
			CurrentPosition += 4;
			break;

		case DPL_SGN4:
			PutLong(outf, p);
			CurrentPosition += 5;
			break;

		default:
			panic("HandleSpecial l=%d", l);
			/* NOTREACHED */
		}
		CurrentPosition += p;
		while (--p >= 0) {
			i = getc(inf);
			putbyte(outf, i);
		}
		if (feof(inf))
			GripeUnexpectedDVIEOF();
		if (ferror(outf))
			error(1, -1, writeerr);
	} else
		while (--p >= 0)
			(void) getc(inf);
}

static void
ReallyUseFont(void)
{
	register struct fontinfo *fi;
	int look = S_LOOKUP;

	fi = (struct fontinfo *)SSearch(FontFinder, CurrentFontIndex, &look);
	if (fi == NULL)
		error(1, 0, "DVI file requested font %ld without defining it",
		    (long)CurrentFontIndex);
	if (fi->fi_reallyused == 0) {
		fi->fi_reallyused++;
		fi->fi_newindex = NextOutputFontIndex++;
		WriteFont(fi);
	}
	if (fi->fi_newindex != OutputFontIndex) {
		PutFontSelector(fi->fi_newindex);
		OutputFontIndex = fi->fi_newindex;
	}
}

/*
 * Write a font selection command to the output file
 */
static void
PutFontSelector(i32 index)
{

	if (index < 64) {
		putbyte(outf, index + DVI_FNTNUM0);
		CurrentPosition++;
	} else if (index < 256) {
		putbyte(outf, DVI_FNT1);
		putbyte(outf, index);
		CurrentPosition += 2;
	} else if (index < 65536) {
		putbyte(outf, DVI_FNT2);
		PutWord(outf, index);
		CurrentPosition += 3;
	} else if (index < 16777216) {
		putbyte(outf, DVI_FNT3);
		Put3Byte(outf, index);
		CurrentPosition += 4;
	} else {
		putbyte(outf, DVI_FNT4);
		PutLong(outf, index);
		CurrentPosition += 5;
	}
}

/*
 * The following table describes the length (in bytes) of each of the DVI
 * commands that we can simply copy, starting with DVI_SET1 (128).
 */
char	oplen[128] = {
	0, 0, 0, 0,		/* DVI_SET1 .. DVI_SET4 */
	9,			/* DVI_SETRULE */
	0, 0, 0, 0,		/* DVI_PUT1 .. DVI_PUT4 */
	9,			/* DVI_PUTRULE */
	1,			/* DVI_NOP */
	0,			/* DVI_BOP */
	0,			/* DVI_EOP */
	1,			/* DVI_PUSH */
	1,			/* DVI_POP */
	2, 3, 4, 5,		/* DVI_RIGHT1 .. DVI_RIGHT4 */
	1,			/* DVI_W0 */
	2, 3, 4, 5,		/* DVI_W1 .. DVI_W4 */
	1,			/* DVI_X0 */
	2, 3, 4, 5,		/* DVI_X1 .. DVI_X4 */
	2, 3, 4, 5,		/* DVI_DOWN1 .. DVI_DOWN4 */
	1,			/* DVI_Y0 */
	2, 3, 4, 5,		/* DVI_Y1 .. DVI_Y4 */
	1,			/* DVI_Z0 */
	2, 3, 4, 5,		/* DVI_Z1 .. DVI_Z4 */
	0,			/* DVI_FNTNUM0 (171) */
	0, 0, 0, 0, 0, 0, 0, 0,	/* 172 .. 179 */
	0, 0, 0, 0, 0, 0, 0, 0,	/* 180 .. 187 */
	0, 0, 0, 0, 0, 0, 0, 0,	/* 188 .. 195 */
	0, 0, 0, 0, 0, 0, 0, 0,	/* 196 .. 203 */
	0, 0, 0, 0, 0, 0, 0, 0,	/* 204 .. 211 */
	0, 0, 0, 0, 0, 0, 0, 0,	/* 212 .. 219 */
	0, 0, 0, 0, 0, 0, 0, 0,	/* 220 .. 227 */
	0, 0, 0, 0, 0, 0, 0,	/* 228 .. 234 */
	0, 0, 0, 0,		/* DVI_FNT1 .. DVI_FNT4 */
	0, 0, 0, 0,		/* DVI_XXX1 .. DVI_XXX4 */
	0, 0, 0, 0,		/* DVI_FNTDEF1 .. DVI_FNTDEF4 */
	0,			/* DVI_PRE */
	0,			/* DVI_POST */
	0,			/* DVI_POSTPOST */
#ifdef ASCIIPTEX
	0, 0, 0, 0, 0,		/* 250 .. 254 */
	0,			/* DVI_DIR */
#else /* !ASCIIPTEX */
	0, 0, 0, 0, 0, 0,	/* 250 .. 255 */
#endif /* !ASCIIPTEX */
};

/*
 * Here we read the input DVI file and write relevant pages to the
 * output DVI file. We also keep track of font changes, handle font
 * definitions, and perform some other housekeeping.
 */
static void
HandleDVIFile(void)
{
	register int c, l;
	register i32 p = 0;	/* avoid uninitialized warning */
	register int CurrentFontOK = 0;
	int doingpage = 0;

	/* Only way out is via "return" statement */
	for (;;) {
		c = getc(inf);	/* getc() returns unsigned values */
		if (DVI_IsChar(c)) {
			/*
			 * Copy chars, note font usage, but ignore if
			 * page is not interesting.
			 */
			if (!UseThisPage)
				continue;
			if (!CurrentFontOK) {
				ReallyUseFont();
				CurrentFontOK++;
			}
			putbyte(outf, c);
			CurrentPosition++;
			continue;
		}
		if (DVI_IsFont(c)) {	/* note font change */
			CurrentFontIndex = c - DVI_FNTNUM0;
			CurrentFontOK = 0;
			continue;
		}
		if (c == EOF)
			GripeUnexpectedDVIEOF();
		if ((l = (oplen - 128)[c]) != 0) {	/* simple copy */
			if (!UseThisPage) {
				while (--l > 0)
					(void) getc(inf);
				continue;
			}
			CurrentPosition += l;
			putbyte(outf, c);
			while (--l > 0) {
				c = getc(inf);
				putbyte(outf, c);
			}
			if (ferror(outf))
				error(1, -1, writeerr);
			continue;
		}
		if ((l = DVI_OpLen(c)) != 0) {
			/*
			 * Handle other generics.
			 * N.B.: there should only be unsigned parameters
			 * here (save SGN4), for commands with negative
			 * parameters have been taken care of above.
			 */
			switch (l) {

			case DPL_UNS1:
				p = getc(inf);
				break;

			case DPL_UNS2:
				fGetWord(inf, p);
				break;

			case DPL_UNS3:
				fGet3Byte(inf, p);
				break;

			case DPL_SGN4:
				fGetLong(inf, p);
				break;

			default:
				panic("HandleDVIFile l=%d", l);
			}

			/*
			 * Now that we have the parameter, perform the
			 * command.
			 */
			switch (DVI_DT(c)) {

			case DT_SET:
			case DT_PUT:
				if (!UseThisPage)
					continue;
				if (!CurrentFontOK) {
					ReallyUseFont();
					CurrentFontOK++;
				}
				putbyte(outf, c);
				switch (l) {

				case DPL_UNS1:
					putbyte(outf, p);
					CurrentPosition += 2;
					continue;

				case DPL_UNS2:
					PutWord(outf, p);
					CurrentPosition += 3;
					continue;

				case DPL_UNS3:
					Put3Byte(outf, p);
					CurrentPosition += 4;
					continue;

				case DPL_SGN4:
					PutLong(outf, p);
					CurrentPosition += 5;
					continue;
				}

			case DT_FNT:
				CurrentFontIndex = p;
				CurrentFontOK = 0;
				continue;

			case DT_XXX:
				HandleSpecial(c, l, p);
				continue;

			case DT_FNTDEF:
				HandleFontDef(p);
				continue;

#ifdef ASCIIPTEX
			case DT_DIR:
				if (!UseThisPage)
					continue;
				ptexdvi = 1;

				putbyte(outf, c);
				putbyte(outf, p);
				CurrentPosition += 2;
				continue;
#endif /* ASCIIPTEX */

			default:
				panic("HandleDVIFile DVI_DT(%d)=%d",
				      c, DVI_DT(c));
			}
			continue;
		}

		switch (c) {	/* handle the few remaining cases */

		case DVI_BOP:
			if (doingpage)
				GripeUnexpectedOp("BOP (during page)");
			BeginPage();
			doingpage = 1;
			CurrentFontOK = 0;
			break;

		case DVI_EOP:
			if (!doingpage)
				GripeUnexpectedOp("EOP (outside page)");
			EndPage();
			doingpage = 0;
			break;

		case DVI_PRE:
			GripeUnexpectedOp("PRE");
			/* NOTREACHED */

		case DVI_POST:
			if (doingpage)
				GripeUnexpectedOp("POST (inside page)");
			return;

		case DVI_POSTPOST:
			GripeUnexpectedOp("POSTPOST");
			/* NOTREACHED */

		default:
			GripeUndefinedOp(c);
			/* NOTREACHED */
		}
	}
}