/* Ln03DVI translates a TeX DVI file to an LN03 format file. 

Ln03DVI is still being developed. Copyright (c) 1985, 1986, 1987
by Digital Equipment Corporation, Maynard, Massachusetts,
USA. Originial Author: Flavio Rose (...!decwrl!dvinci.dec.com!rose)

This version of Ln03DVI is maintained by Matt Thomas.
Please send all bug reports to either:
    ...!decwrl!thebay.dec.com!mthomas (UUCP)
    mthomas@thebay.dec.com (Internet) */

/* Dvi2ln3 is based on the publicly-available program DVItype,
written by David R. Fuchs of Stanford University; and also
on earlier DEC programs, Dvi2lng, Topp and LN03Topp, for the
LN01 and LN03 laser printers. This program is not a DEC
product and is not guaranteed to work. 

Dvi2ln3 is written in VAX C. Specific VAX and VMS
dependencies have generally been avoided, however. The
reader may find them by searching for the strings VAX and
VMS in this file. 

During development, double square brackets [[ ]] in a
comment indicate some places where the code needs to be
improved. 

[[Among the useful things that still need to be done:
differentiating between int and long variables so this can
be ported more easily to 16-bit architectures; testing to
see if malloc returns 0; a \special for ROM fonts.]] 

Development history:

Feb. 85:    Did some early work on Dvi2ln3, translating bits
	    and pieces of Dvi2lng. Concluded, however, that it
	    was better to translate LN03Topp and Dvi2lng into
	    C first. The reason for this is that code which
	    mimics an existing program is easier to write and
	    to test. 

5/15/85:    At this date, the old LN03Topp program has been
	    successfully translated into C (except for the
	    ability to read files over DECnet). At this point,
	    did some further cleanup of the Dvi2ln3 source. 

6/4/85:	    Coding of Dvi2ln3 begins in earnest. Merging bits
	    and pieces from various places. Chucking chunks
	    and all that junk from LN03Topp; pass2 is just
	    straightforward translation. 

6/22/85:    Cleanup after initial debugging. Ready to
	    distribute. 

10/8/85:    Adding \special's to imitate Textset's DVIAPS program.
	    Corrected bug in parsing of \specials. Version 1.

10/15/85:   More changes for specials. Version 2.

11/8/85:    Fixed bug in ln03:defpoint \special. Version 3.

11/15/85:   Changed way information about font size is passed
	    back by add_txf_to_lnf. Add PXL-reading
	    capability. Version 4. 

11/21/85:   Error handling has been reformed. Still version 4.

12/12/85:   Bug correction in handling of plotfile special. 
	    Version 5.

1/7/86:	    Clear all fonts from memory at beginning of 
	    document. Version 6.

1/16/86:    Fixed bug in dvi2ln3nft.c, nftf was not being
	    closed after use. Version 7. (Bug found by Mark
	    DeVries.) 

3/4/86:	    Support for landscape added -- very easy, if only
	    I had known. Fixed bug found by Mark DeVries,
	    error returned if \special selects device other
	    than LN03. Version 8. 

3/28/86:    Conditionalization for Ultrix. #ifndef vms ==
	    #ifdef ultrix. Still emits 8-bit characters.
	    Should be unchanged under VMS. getenv is used to
	    replace logicals. Version 9. 

4/4/86:     Added support for 7-bit only environments, 
	    conditionalized on the SEVENBIT symbol. Still 
	    version 9.

4/16/86:    Final changes to make compilation under Ultrix 
	    clean. Still version 9.

6/27/86:    Finally added option for A4-sized paper. Version 
	    10.

11/6/86:    Bug when /n= is specified and /s= is not. Fixed
	    rule computation. Version 11.

02/20/87:   Clean up messages.  Add PK file support to DVI2LN3NFT.C.
	    Genericize the PK file support.  Rename from Dvi2ln3 to
	    Ln03DVI to keep this version indepedent of the original.
	    Prepare/cleanup for realease on the Unix-Tex distribution.

5/18/87:    Move version info to a seperate file, ln03version.c.
*/ 

#ifdef vms
#include stdio
#include ctype
#else
#include <stdio.h>
#include <ctype.h>
#endif

/* Ultrix seems to want this: */

#ifdef bsd4_2
# define strchr index 
extern int errno;
#endif

#ifndef vms
char *strchr(), *malloc(), *getenv();
# define SEVENBIT 1
#endif

/* The version information */

extern char ln03dvi_version[];


/* In VMS, we declare all global variables to be globaldef.
This is not really necessary, just an old habit from working
with other VMS languages. It's done with #define's, so it
may easily be undone when porting the program to other
systems. */ 

#ifdef vms
#define GLOBAL globaldef
#define EXTERN globalref
#else
#define GLOBAL 
#define EXTERN extern
#endif


/* Here begins a long list of global variables. */

/* hoff is the horizontal offset in pixels to be added to
all dimensions read in; voff is the corresponding vertical
offset. */ 

GLOBAL int hoff, voff;
GLOBAL FILE *tfmfile,*outfile;
GLOBAL int dvifile;

/* [[We are finally implementing the speed optimization of
eliminating getc's on dvifile. Hence the following:]] */

GLOBAL unsigned char dvibuf[513];
GLOBAL int dvifp,dvieof;
#define mygetcdvi ((dvifp < 512) ? dvibuf[dvifp++] : \
	moredvi()) 

/* Each page in a DVI file is identified by ten longwords,
which appear immediately after each bop (beginning of page)
command. Ln03DVI, like DVItype, supports certain options
that allow one to print only selected pages. The following
variables are used for this purpose. 

Num_pages is a count of how many pages have been passed to
the output. Max_pages is the user-specified maximum number
of pages to pass. How_many_counts denotes the number of
identifying longwords to take into account when searching
for the user-specified starting page. The user specifies the
starting page as the first one whose identifying longwords
match certain specified values, stored in start_page.
However, identifying longword i is only required to match
the value in start_page[i] if use_count[i] is nonzero. */ 

GLOBAL long int num_pages,max_pages;
GLOBAL int how_many_counts,use_count[10];
GLOBAL long int start_page[10];

/* When the output file can have no characters with code >
127, the user should employ a LN03DVI which is recompiled
with the symbol SEVENBIT defined. Such a Ln03DVI will run slower
than one which is allowed eight bits, and produce larger
output files. */ 

#ifdef SEVENBIT
GLOBAL int right7; 
#endif

/* FILESPECLEN is the maximum size of a file specification
under VMS. [[Perhaps arrays of fixed size should not be
used, but rather malloc should be employed...]] */ 

#define FILESPECLEN 252

/* landscape says whether we are printing in landscape or
portrait. */ 

GLOBAL char landscape;

/* a4_paper says whether we are printing on a4 paper. */

GLOBAL char a4_paper;

/* The main routine deals with the command line arguments,
opens the dvi file, and then calls various other routines to
handle the "passes". There are two passes, each of which
involves reading the DVI file from start to finish; in
between, the font load is constructed. */ 

main(argc,argv) 
int argc;
char *argv[];
{
    int status,i,jnam,jext;
    char infnam[FILESPECLEN];

    if (argc < 2) {
	printf("Usage:\tln03dvi [options] dvifile\n");
	printf("    -h hoffset\t\t(horizontal offset in pixels)\n");
	printf("    -v voffset\t\t(vertical offset in pixels)\n");
	printf("    -s XYX\t\t(starting page number)\n");
	printf("    -n pages\t\t(number of pages)\n");
	printf("    -l\t\t\t(landscape mode)\n");
	printf("    -e\t\t\t(european A4 paper)\n");
	goto exit_label;
	}

    printf("\n\tLn03DVI %s\n\n",ln03dvi_version);

/* Now decipher the options off the command line. */

#ifdef SEVENBIT
    right7 = 0;
#endif
    max_pages = 1000000000;
    how_many_counts = 0;
    hoff = 300;
    voff = 300;
    landscape = 0;
    a4_paper = 0;
    for (i=1; i<argc; i++) {

	/* The extension of the input file defaults to .dvi. Locate
	the filename field within the filespec parameter, set jname
	to point to beginning, jext to point to one place after end.
	[[This code is of course dependent on the VMS filespec
	syntax.]] */ 

	if (argv[i][0] == '-') {
	    i += command_line_option( &argv[i], argc-i );
	} else {
	    strcpy(infnam,argv[i]);

	    /* The extension of the input file defaults to .dvi. Locate
	    the filename field within the filespec parameter, set jname
	    to point to beginning, jext to point to one place after end.
	    [[This code is of course dependent on the VMS filespec
	    syntax.]] */ 
      
	    find_filename(infnam,&jnam,&jext);
	    if (infnam[jext] == '\0') strcat(infnam,".dvi");
	    dvifile = open(infnam,0);
	    if (dvifile < 0) {
		fprintf(stderr,"Couldn't open dvi file ");
		perror(infnam);
		goto exit_label;
	    }
	    dvieof = 0;
	    dvifp = 512;
	}
    }

/* Now do the passes */

    status = pass1();
    if (status != 0) goto exit_label; 
#ifdef vms || bsd4_2
    if (lseek(dvifile,0,0) == -1) {
	printf("\n Couldn't rewind dvi file.");
	goto exit_label;
    }
#else
    lseek(dvifile,0,0);
#endif
    dvieof = 0;
    dvifp = 512;

    status = open_output_file(infnam,jnam,jext,".ln3");
    if (status != 0) { perror("Couldn't open output file");
	goto exit_label; }

    status = make_font_load();
    if (status != 0) goto exit_label;

    pass2();
    printf("\n");

    fprintf(outfile,"\033[!p");
    close(dvifile);
    fclose(outfile);

exit_label:
/*
#ifndef vms
    printf("\n");
#endif
*/
    ;
}

/* Find_filename finds the filename part of a filespec
passed in s, returning the index of the first character in
*ns, and the index of the character after the last in *ne.
[[This works under VMS and Unix. MS-DOS still needs work.]]
*/ 

int find_filename(s,ns,ne)
char s[];
int *ns,*ne;
{
    int jnam,jext,j,slen;

    slen = strlen(s);
    jnam = 0;
    for (j = slen-1; j >= 0; j--) {
#ifdef vms
	if (s[j] == ':' || s[j] == ']' ||
	    s[j] == '>') {
#else
	if (s[j] == '/') {
#endif
	    jnam = j+1;
	    break;
	}
    }

    jext = slen;	
    for (j = jnam; j < slen; j++) {
#ifdef vms
	if (s[j] == '.' || s[j] == ';') {
#else
	if (s[j] == '.') {
#endif
	    jext = j;
	    break;
	}
    }

    *ns = jnam;
    *ne = jext;
}

/* Moredvi reads up to 512 bytes from the dvi file and puts
them in the dvibuf. It also returns the first byte. Any
missing bytes are filled in with 248, the dvi command code
for the postamble. 

[[The read is not retried. Thus, the dvifile must be either
stream or fixed-length 512 byte records for this to work.
TeX-generated dvi files have fixed-length 512 byte
records.]] */ 

unsigned char moredvi() {
    int i,j;

    i = read(dvifile,dvibuf,512);
    dvifp = 1;
    if (i <= 0) {
	dvieof = 1;
	for (j=0; j<512; j++) dvibuf[j] = 248;
	return(248);
    } else if (i < 512) 
	for (j=i; j<512; j++) dvibuf[j] = 248;
    return(dvibuf[0]);
}


/* ERROR HANDLING: Errors should be reported as close to the
source as possible, so that the maximum amount of
information is available to the user to identify the error. 

Errors in the format of DVI or TFM files are not reported
specifically, since there exist programs, DVItype and
TFtoPL, which diagnose errors in such files. This program
accepts some incorrect DVI files, for example, those with a
bad postamble or bad backpointers. [[However, someday we may
rewrite the program to select pages by using these features
of the DVI format, rather than by skipping unwanted pages.]]
*/ 

GLOBAL char *bad_DVI_message = "Bad DVI file - check it with DVItype\n"; 

/* Command_line_option reads and processes options off the
argument list. At this time, six options are supported. 

The N option sets the maximum number of pages to be printed.
Its syntax is /N=<integer> . 

The H option modifies the default horizontal offset.

The V option modifies the default vertical offset. 

The S option has syntax /S=<pagespec>{.<pagespec>}* where
the {}* denotes repetition, and a <pagespec> is either an
integer or * to indicate any value. An example would be
"/S=*.8.3". 

The meaning of the S option is as follows: In a DVI file,
pages are identified by ten longword values which follow
each bop (beginning of page) command. The value of the S
option indicates which page to start printing on. For
example, "*.8.3" means start printing at the first page
whose second identifying longword is 8 and third is 3. 

The L option says print in landscape.

The E (for European) option says print on A4 paper. */ 

int command_line_option( argv, argc )
char **argv;
int argc;
{
    long int i = 0, k;
    char *u;
    char *t = &argv[0][1];

    if (toupper(t[0]) == 'N') {
	if (isdigit(t[1]))
	    sscanf(&t[2], "%ld", &k);
	else {
	    sscanf(argv[1], "%ld", &k );
	    i += 1;
	}
	max_pages = k;
    } else if (toupper(t[0]) == 'H') {
	if (isdigit(t[1]))
	    sscanf(&t[2], "%ld", &k);
	else {
	    sscanf(argv[1], "%ld", &k );
	    i += 1;
	}
	hoff = k;
    } else if (toupper(t[0]) == 'V') {
	if (isdigit(t[1]))
	    sscanf(&t[2], "%ld", &k);
	else {
	    sscanf(argv[1], "%ld", &k );
	    i += 1;
	}
	voff = k;
    } else if (toupper(t[0]) == 'L') {
	landscape = 1;
    } else if (toupper(t[0]) == 'E') {
	a4_paper = 1;
    } else if (toupper(t[0]) == 'S') {
	if (t[1] == 0) {
	    t = argv[1];
	    i++;
	}
	how_many_counts = 0;
	for (;;) {
	    if (t[0] == '*') {
		use_count[how_many_counts] = 0;
		how_many_counts++;
	    } else if (sscanf(t,"%ld",&k) != 0) {
		use_count[how_many_counts] = 1;
		start_page[how_many_counts] = k;
		how_many_counts++;
	    } else break;
	    u = strchr(t,'.');
	    if (u == 0) break;
	    t = &u[1];
	}
    }
    return(i);
}

/* Open_output_file opens one of the output files, using the
file pointer outfile. The name of the output file is
obtained by appending the string ext to the substring of
infnam beginning at jnam and ending at jext. 

[[This code contains a VMS dependency. We use creat followed
by fdopen to open the file as a normal VMS file
("rat=cr","rfm=var") rather than a STREAM_LF file. Beginning
with VAX C V2.0, this can be done by just calling fopen.]]
*/ 

int open_output_file(infnam,jnam,jext,ext)
char *infnam,*ext;
int jnam,jext;
{
    char outfnam[FILESPECLEN];
    int jj;

    strcpy(outfnam,&infnam[jnam]);
    strcpy(&outfnam[jext-jnam],ext);

#ifdef vms
    jj = creat(outfnam,0,"rat=cr","rfm=var");
#else
    jj = creat(outfnam,0644);
#endif
    if (jj == -1) return(1);
    outfile = fdopen(jj,"w");
    if (outfile == NULL) return(1);

    return(0);
}

/* We use an overlay, as suggested in the DVItype
documentation, to combine these bytes into larger integers.
[[Note that this technique relies on the fact that numbers
on the VAX are stored with the least significant byte first.
The macros below would have to be changed if the program
were to be ported to a machine architecture for which this
is not so.]] 

[[The use of getc is expensive, since getc is a function in
VAX C V2.0. Eventually, one would want to rewrite these
macros to work like the old getc macro.]] */ 

#ifdef BIG_ENDIAN
/* For Sun's */
#define two_bytes_u lcx.uc[2] = mygetcdvi; \
    lcx.uc[3] = mygetcdvi; lcx.uc[1] = 0; lcx.uc[0] = 0

#define two_bytes_s lcx.c[2] = mygetcdvi; \
    lcx.c[3] = mygetcdvi;  \
    if (lcx.c[2] >= 0) { lcx.uc[1] = 0; lcx.uc[0] = 0 ;} \
    else { lcx.uc[1] = 255; lcx.uc[0] = 255; }

#define three_bytes_u lcx.uc[1] = mygetcdvi; lcx.uc[2] = mygetcdvi; \
    lcx.uc[3] = mygetcdvi; lcx.uc[0] = 0

#define three_bytes_s lcx.c[1] = mygetcdvi; lcx.c[2] = mygetcdvi; \
    lcx.c[3] = mygetcdvi;  \
    lcx.uc[0] = (lcx.c[1] >= 0) ? 0 : 255;

#define four_bytes lcx.c[0] = mygetcdvi; \
    lcx.c[1] = mygetcdvi; lcx.c[2] = mygetcdvi; \
    lcx.c[3] = mygetcdvi; 

#else  /* Not big endian */

GLOBAL union lc { long int l; unsigned long int ul; char c[4]; 
	    unsigned char uc[4]; } lcx;

#define two_bytes_u lcx.uc[1] = mygetcdvi; \
    lcx.uc[0] = mygetcdvi; lcx.uc[2] = 0; lcx.uc[3] = 0
#define two_bytes_u lcx.uc[1] = mygetcdvi; \
    lcx.uc[0] = mygetcdvi; lcx.uc[2] = 0; lcx.uc[3] = 0

#define two_bytes_s lcx.c[1] = mygetcdvi; \
    lcx.c[0] = mygetcdvi;  \
    if (lcx.c[1] >= 0) { lcx.uc[2] = 0; lcx.uc[3] = 0 ;} \
    else { lcx.uc[2] = 255; lcx.uc[3] = 255; }

#define three_bytes_u lcx.uc[3] = mygetcdvi; lcx.uc[1] = mygetcdvi; \
    lcx.uc[0] = mygetcdvi; lcx.uc[2] = 0

#define three_bytes_s lcx.c[2] = mygetcdvi; lcx.c[1] = mygetcdvi; \
    lcx.c[0] = mygetcdvi; \
    lcx.uc[3] = (lcx.c[2] >= 0) ? 0 : 255;

#define four_bytes lcx.c[3] = mygetcdvi; \
    lcx.c[2] = mygetcdvi; lcx.c[1] = mygetcdvi; \
    lcx.c[0] = mygetcdvi; 

#endif

/* Knuth's programs like to hardcode fixed maximum sizes for
various things, for example, the maximum number of fonts
allowed in a DVI file. In general, it is preferable to use
the C function malloc to allocate storage as needed. That is
what we generally do in this Ln03DVI, but there are some
residues of the Knuthian approach, like MAXTEXFONTS below.
By the way, we never attempt to return any storage to the
system. 

[[Eventually, it would be better to get rid of MAXTEXFONTS
and use a linked list of records instead. There would be no
cpu time penalty to using a linked list, because the
function set_curf below does a linear search through the
font array anyway.]] 

Txf is a data structure describing a TeX font. */

#define MAXTEXFONTS 100

struct txf { unsigned char chu[256]; int bc, ec; long int space, design_size,
    scaled_size; int nchs; };

GLOBAL struct txf *txfa[MAXTEXFONTS+1];

/* Font_name points to strings containing TeX font names.
Those strings are created with malloc as needed. */ 

GLOBAL char *font_name[MAXTEXFONTS+1]; 

/* Font width information needs to be read from TFM files.
TFM is a special format defined by TeX. "Ln03DVI" stores each
width in a longword. DVItype tries to save space by a
two-level width storage method. We just allocate an array of
widths for each font with malloc. 

[[We don't check that font checksums match in Ln03DVI,
because there are a lot of slightly obsolete TFMs floating
around which would result in a checksum error, but seem to
give perfectly reasonable formatted output nonetheless.]] */

GLOBAL long int *font_width[MAXTEXFONTS+1];

/* TeX fonts are referred to by their internal numbers,
which go from 0 to nf-1. The DVI file refers to them by
external numbers, hence the array to_ext used to convert
internal numbers to external numbers. Curf is the internal
font number of the current font in the DVI file. Curchu
points to the 'chu' (character used) array of the current
font. */ 

GLOBAL int to_ext[MAXTEXFONTS+1],
    nf,
    curf;
GLOBAL unsigned char *curchu;

/* In some switch statements, a lot of cases have to be
enumerated. We employ the following Knuthian macro for that
purpose: */ 

#define four_cases(_x1) case _x1: case _x1+1: case _x1+2: case _x1+3: 

/* We define a lot of constants corresponding to the DVI
operation codes. These are copied from DVItype. */ 

#define id_byte 2    /* current version of the dvi format */
#define set_char_0 0 /* typeset character 0 and move right */
#define set1 128     /* typeset a character and move right */
#define set_rule 132 /* typeset a rule and move right */
#define put1 133     /* typeset a character */
#define put_rule 137 /* typeset a rule */
#define nop 138      /* no operation */
#define bop 139      /* beginning of page */
#define eop 140      /* ending of page */
#define push 141     /* save the current positions */
#define pop 142      /* restore previous positions */
#define right1 143   /* move right */
#define w0 147       /* move right by |w| */
#define w1 148       /* move right and set |w| */
#define x0 152       /* move right by |x| */
#define x1 153       /* move right and set |x| */
#define down1 157    /* move down */
#define y0 161       /* move down by |y| */
#define y1 162       /* move down and set |y| */
#define z0 166       /* move down by |z| */
#define z1 167       /* move down and set |z| */
#define fnt_num_0 171 /* set current font to 0 */
#define fnt1 235     /* set current font */
#define xxx1 239     /* extension to dvi primitives (\special) */
#define xxx4 242     /* potentially long extension to dvi primitives */
#define fnt_def1 243 /* define the meaning of a font number */
#define pre 247      /* preamble */
#define post 248     /* postamble beginning */
#define post_post 249 /* postamble ending */
#define undefined_command 250

GLOBAL long int mag, num, den;
GLOBAL double conv, unmag_conv;

/* Read_preamble reads the preamble of the dvi file. The
comment is thrown away. The format version number is
checked. The magnification, numerator, and denominator are
remembered in the globals mag, num, den. The float values
conv and unmag_conv serve to convert measurements from DVI
units to pixels. */ 

int read_preamble() {
    unsigned int i;
    int j;

    i = mygetcdvi;
    if (i != pre) return(1);
    i = mygetcdvi;
    if (i != id_byte) return(1);
    four_bytes; num = lcx.l;
    if (num <= 0) return(1);
    four_bytes; den = lcx.l;
    if (den <= 0) return(1);
    four_bytes; mag = lcx.l;
    if (mag <= 0) return(1);

    unmag_conv = (num/254000.0) * (300.0/den);
    conv = unmag_conv * (mag/1000.0);

/* Skip over the comment field. */
    
    i = mygetcdvi;
    for (j=0; j<i; j++) mygetcdvi;
    return(0);
}

/* The dvi file format requires us to keep track of various
quantities, among them the horizontal and vertical positions
h and v, and four values referred to simply as x, y, z and
w. We also keep pixel-rounded versions of h and v, called hh
and vv. */ 

GLOBAL long h, v, x, y, z, w;
GLOBAL int hh, vv;

/* The following function, copied from DVItype, reads from
the DVI file the first parameter of the current DVI command.
In the case of functions whose first parameter is implicit,
such as set_char_0 through set_char_127, the implicit
parameter is returned. */ 

long first_par(o)
int o;
{
    unsigned int i;

    if ((o >= set_char_0) && (o < set_char_0+128))
	return(o-set_char_0);
    if ((o >= fnt_num_0) && (o < fnt_num_0+64))
	return(o-fnt_num_0);
    switch (o) {
	case set1:
	case put1:
	case fnt1:
	case xxx1:
	case fnt_def1:
	    i = mygetcdvi;
	    return(i);
	case set1+1:
	case put1+1:
	case fnt1+1:
	case xxx1+1:
	case fnt_def1+1:
	    two_bytes_u;
	    return(lcx.ul);
	case set1+2:
	case put1+2:
	case fnt1+2:
	case xxx1+2:
	case fnt_def1+2:
	    three_bytes_u;
	    return(lcx.ul);
	case right1:
	case w1:
	case x1:
	case down1:
	case y1:
	case z1:
	    return(mygetcdvi);
	case right1+1:
	case w1+1:
	case x1+1:
	case down1+1:
	case y1+1:
	case z1+1:
	    two_bytes_s;
	    return(lcx.l);
	case right1+2:
	case w1+2:
	case x1+2:
	case down1+2:
	case y1+2:
	case z1+2:
	    three_bytes_s;
	    return(lcx.l);
	case set_rule:
	case put_rule:
	case right1+3:
	case w1+3:
	case x1+3:
	case down1+3:
	case y1+3:
	case z1+3:
	case set1+3:
	case put1+3:
	case fnt1+3:
	case xxx1+3:
	case fnt_def1+3:
	    four_bytes;
	    return(lcx.l);
	case w0:
	    return(w);
	case x0:
	    return(x);
	case y0:
	    return(y);
	case z0:
	    return(z);
	default:
	    return(0);
    }
}

/* Pass1 reads from the DVI file until the last page that
has to be processed, as determined by the page selection
data structures. Font definitions are processed, as are font
selections; after the starting page begins, pass1 records
which characters are used from which fonts. Other commands
are ignored in pass1. Return 1 if something goes wrong, e.g.
if the DVI file comes to a premature end. This resembles
skip_pages below. */ 

int pass1() {

    unsigned int k;
    long int p;
    int i;
    char startp;
    
    if (read_preamble() != 0) {
	fprintf(stderr,bad_DVI_message);
	return(1);
    }

    num_pages = 0;

    for (;;) {
	if (dvieof) {
	    fprintf(stderr,bad_DVI_message);
	    return(1);
	}
	k = mygetcdvi;
	if (k == post) return(0);
	if (k >= set_char_0 && k < set_char_0+128) {
	    p = k;
	    k = set1;
        } else if (k >= fnt_num_0 && k < fnt_num_0+64) {
	    p = k-fnt_num_0;
	    k = fnt1;
        } else p = first_par(k);

	switch (k) {
	    case bop:
		startp = 1;
		for (i=0; i<10; i++) {
		    four_bytes;
		    if (i < how_many_counts && use_count[i] &&
			    lcx.l != start_page[i]) startp = 0;
		    }
		four_bytes;
		if (startp != 0 || num_pages > 0) {
		    num_pages++;
		    if (num_pages > max_pages) return(0);
		}
		break;
	    case set_rule:
	    case put_rule:
		four_bytes;
	        break;
	    four_cases(fnt_def1)
		i = define_font(p);
		if (i != 0) return(1);
		break;
	    four_cases(fnt1)
		if (num_pages > 0) set_curf(p);
		break;
            four_cases(set1)
	    four_cases(put1)
		if (num_pages > 0)
		    txfa[curf] -> chu[p] = 1;
		break;

/* \special's are currently ignored in pass1, and handled
only in pass2. [[This will change if the putchar special is
implemented.]] */ 

	    four_cases(xxx1)
		for (; p>0; p--) mygetcdvi;
		break;
            default:
		break;
	}
    }
/*  return(0); /* Unreachable */
}

/* FONT LOAD BUILDING: The hardest thing Ln03DVI has to do
is to build an LN03 font load that contains the glyphs
required to print the DVI file. The following code pertains
to that effort. 

LN03 fonts come in two flavors. Left fonts are invoked by
character codes 33 to 126. Right fonts are invoked by
character codes 161 to 254. Hence: */ 

#define leftfirst 33
#define rightfirst 161
#define leftlast 126
#define rightlast 254

/* It is believed that there is a maximum of 32
downline-loaded LN03 fonts. We always deal with these in
pairs, using one as a left font, the other as a right font.
Hence we have a maximum of 16 pairs. */ 

#define maxnfonts 16

/* We keep track of the true last character in each LN03
font pair; the width of each character; and the LN03 name
assigned to that pair. [[Yikes. Chw is an unsigned char
here; it should be at least an unsigned short.]] */ 

GLOBAL int lastch[maxnfonts];
GLOBAL unsigned char chw[maxnfonts][256];
GLOBAL char fname[maxnfonts][32];

/* Txf is a record structure describing a TeX font. Txfa is
an array of txf records. Txf2lnf describes the mapping
between TeX fonts and pairs of LN03 fonts. Because the
constructed LN03 font load has just the glyphs that are
needed, we can often cram more than one TeX font into a pair
of LN03 fonts. */ 

GLOBAL int txf2lnf[MAXTEXFONTS];

/* Maxfontnos reflects the fact that LN03 fonts must be
denoted by a number from 10 to 19 in order to be selected as
the LN03's current font. */ 

#define maxfontnos 9

/* The LN03 font-denoting numbers 10-19 have to be allocated
among the fonts. The useno array keeps track of which number
a font is using, -1 if the font currently doesn't have any
number. The whouses array says which font is using a given
number. */ 

GLOBAL int useno[maxnfonts],whouses[maxfontnos];

/* After the font load we declare the right and bottom
margins we are going to use; these are always the maximum
allowed values. */ 

GLOBAL int maxrmar,maxbmar;

/* The global ras_len_added is employed by the
font-load-creating code to communicate how many bytes of
raster information it adds to the font load each time it is
called. [[Maybe there should be no EXTERNs in the main code
file, just GLOBALs?]] The right thing would be to put all
these declarations in .h's.]] */ 

EXTERN long ras_len_added;

#define max(x,y) (((x)>(y))?(x):(y))
#define min(x,y) (((x)<(y))?(x):(y))

/* Make_font_load calls on other procedures to generate the
LN03 font load. It writes the opening lines of the output
file, too. */ 

int make_font_load() {
    
    int i,j,jj,k,l,fno,maxfno,chsize;
    long int totsize;
    int lnfcnt,txfcnt,the_txf,txf_size,lnfleft;
    int txford[MAXTEXFONTS];
    char cnt[3];

    totsize = 0;
    chsize = 0;
    curf = 0;
    for (i=0; i<maxnfonts; i++) 
	for (j=0; j<256; j++) chw[i][j] = 0;

    for (jj=0; jj<MAXTEXFONTS; jj++) txf2lnf[jj] = -1;

/* Fill the fname strings with different valid LN03 font
names. [[This initialization could be done statically, but
then maxnfonts would be more hardcoded.]] */ 

    for (i=0; i<maxnfonts; i++) 
        strcpy(fname[i],"U000000002SK00GG0001UZZZZ02F000");
    for (jj=1; jj<maxnfonts; jj++) {
	sprintf(cnt,"%02d",jj);
	strncpy(&(fname[jj][5]),cnt,2);
    }

/* The margins are set to values that seem appropriate for
American 8 1/2 by 11" paper. It is not clear if this needs
to be changed for European A4 paper. Not changing it might
deprive Europeans of access to the bottom 1.5cm of their
paper. 

I have tried to set the margins appropriately according
to the paper type (a4 or 8 1/2 x 11"), and to throw away
text which is set outside. [[However, text too close to the
bottom margin still results in an apparently undocumented
LN03 page eject.]] */ 

    if (landscape == 1) {
	if (a4_paper == 0) {
	    maxrmar = 3300;
	    maxbmar = 2475;    
	} else {
	    maxrmar = 3475;
	    maxbmar = 2475;    
	}
    } else {
	if (a4_paper == 0) {
	    maxrmar = 2550;
	    maxbmar = 3300;
	} else {
	    maxrmar = 2550;
	    maxbmar = 3475;    
	}
    } 

/* In the following, esc[?21 J means print in landscape on 8
1/2 x 11 inch paper, esc[?22 J means print in portrait on A4
paper, esc[?23 J means landscape on A4 paper, esc[?27h means
"advance the carriage by the character width when you set a
character", esc[11h and esc[7 I together mean to interpret
all dimensions in escape sequences as pixel units; esc[?52h
means our origin of coordinates is the upper left edge of
the paper; esc[%dt means the "maximum length" of the paper
is maxbmar pixels. */ 

    fprintf(outfile,"\033[!p");
    if (landscape == 1 && a4_paper == 0) fprintf(outfile,"\033[?21 J");
    if (landscape == 0 && a4_paper == 1) fprintf(outfile,"\033[?22 J");
    if (landscape == 1 && a4_paper == 1) fprintf(outfile,"\033[?23 J");
    fprintf(outfile,"\033[?7l\033[?27h\033[11h\033[7 I\033[?52h\033[%dt\n",
	maxbmar);

    for (i=0; i<maxnfonts; i++) useno[i] = -1;
    for (i=0; i<maxfontnos; i++) whouses[i] = -1;
    maxfno = -1;

/* Write font loading escape sequence onto outf. The ;0y
causes all previously downloaded fonts to be cleared from
the LN03's font memory. */ 

    fprintf(outfile,"\033P0;1;0y");

/* Count how many glyphs each font requires. */

    for (fno=0; fno<nf; fno++) {

	txfa[fno] -> nchs = 0;
	for(i=0; i<256; i++) 
	    if (txfa[fno] -> chu[i] != 0) txfa[fno] -> nchs++;

	if (txfa[fno] -> nchs > 188)  goto need_empty_slots;
	chsize += txfa[fno] -> nchs;
    }
    printf("Font load to contain %d glyphs.\n",chsize);


/* Now we have to allocate TeX fonts to LN03 font pairs and
perform the actual load. The goal is to use as few LN03
fonts as possible. 

I don't know any way to do the allocation optimally, so a
first-fit heuristic is used. 

1.	Find the largest unassigned TeX font. If none, exit,
	we're done. Number of glyphs used is the measure of size. 

2.	Allocate an LN03 font pair for that TeX font and put
	the TeX font into it. 

3.	Find the largest remaining TeX font that fits in
	what is left of that LN03 font pair. 

    3.1. if none exists, go to 1. 
    3.2. if one exists, put it in the font pair and go back 
	 to 3. 

The txford array contains the TeX font numbers in the order
that they are assigned. Txfcnt keeps track of how many TeX
fonts have been assigned so far. */ 

    lnfcnt = 0;
    txfcnt = 0;
    for (i=0; i<MAXTEXFONTS; i++) txford[i] = -1;

    while (1) {

/* Find largest unassigned TeX font */

	lnfleft = rightlast-rightfirst+1+leftlast-leftfirst+1;
	txf_size = -1;
	for (j = 0; j < MAXTEXFONTS; j++) {
	    if (txfa[j] != 0 && txf2lnf[j] == -1 
		&& txfa[j] -> nchs > txf_size) {
		txf_size = txfa[j] -> nchs;
		the_txf = j;
	    }
	}
	if (txf_size <= 0)  goto assignment_done;
	if (lnfcnt > maxnfonts)  goto too_complex;
	if (txf_size > lnfleft)  goto need_empty_slots;

/* Now allocate new LN03 font pair and put the current TeX
font into it */ 

	txf2lnf[the_txf] = lnfcnt;
	txford[txfcnt] = the_txf;
	txfcnt++;
	k = leftfirst-1;
	for (j = 0; j <= 255; j++) {
	    if (txfa[the_txf] -> chu[j] != 0) {
		k++;
		if (k == leftlast+1)  k = rightfirst;
		lnfleft--;
		txfa[the_txf] -> chu[j] = k; 
	    }
	}
	lastch[lnfcnt] = k;

/* Now try to fill the remaining part of the LN03 font pair
using other TeX fonts */ 

	while (1) {

	    txf_size = -1;
	    for (j = 0; j < MAXTEXFONTS; j++) {
		if (txfa[j] != 0 && txf2lnf[j] == -1
		    && txfa[j] -> nchs > txf_size 
		    && txfa[j] -> nchs <= lnfleft) {
		    txf_size = txfa[j] -> nchs;
		    the_txf = j;
		}
	    }
	    if (txf_size <= 0)  break;

	    txf2lnf[the_txf] = lnfcnt;
	    txford[txfcnt] = the_txf;
	    txfcnt++;
	    k = lastch[lnfcnt];
	    for (j=0; j<=255; j++) {
		if (txfa[the_txf] -> chu[j] != 0) {
		    k++;
		    lnfleft--;
		    if (k == leftlast+1) k = rightfirst;
		    txfa[the_txf] -> chu[j] = k; 
		}
	    }
	    lastch[lnfcnt] = k;
	}
	
	lnfcnt++;
    }

assignment_done:

/* At this point, the TeX fonts have been assigned to LN03
font pairs. The assignment is reflected in the arrays
txf2lnf, lastch and txford. It remains to actually generate
the desired font load. This has to be done carefully, since
the function add_txf_to_lnf only supports adding glyphs to
an LN03 font pair in ascending order of character code. */ 

    for (j=0; j<txfcnt; j++) {
	k = txford[j];
	if (j != 0 && txf2lnf[k] != txf2lnf[txford[j-1]])  
	    fprintf(outfile,",\n");
	add_txf_to_lnf(txf2lnf[k],k);	
	totsize += ras_len_added;
    }

/* [[At this point we ought to add code that writes a
message saying how much font RAM the load will occupy. But
there is no documentation for determining that! So, we make
the following compromise:]] */ 

    printf("Approximate size of font load: %ld bytes\n",totsize);

/* Now output escape sequences to the LN03 that assign the
available font numbers to the first ten font pairs in the
load. [[We may want to insert a few \n's in the following to
keep the line from getting too long.]] */ 

    fprintf(outfile,"\n;Ln03DVI 12 font load\033\\");
    fprintf(outfile,"\033[1;%ds\033[%dt\033[1;%dr",maxrmar,maxbmar,maxbmar);
    for (j=0; j <= min(maxfontnos,lnfcnt-1); j++) {
	useno[j] = j;
	whouses[j] = j;
	k = fname[j][16];
	fname[j][16] = '\0';
	fprintf(outfile,"\033P1;1%d}%s\033\\",j,fname[j]);
	fname[j][16] = k;
    }
    fprintf(outfile,"\033[10m");

    return(0);

too_complex:
    fprintf(stderr,"Can't construct a font load:\n");
    fprintf(stderr,"Dvi file uses too many glyphs from too many different fonts.\n");
    return(1);

/* [[We need to determine what the real limit is on the
number of LN03 fonts, and refine the test to detect if it is
being exceeded. Fortunately, only a very complex DVI file
could exceed the limit.]] */ 

need_empty_slots:
    {
	int msg = (100.0*conv*txfa[fno] -> scaled_size)/
	    (unmag_conv*txfa[fno] -> design_size) + 0.5;

	fprintf(stderr,"Font %s",font_name[fno]);
	if (msg != 100) printf(" (@ %d%%)",mag);
	fprintf(stderr," uses > 188 characters. Can't handle that.\n");
	return(1);
    }

/* [[The error message above should be fixed to specify the
magnification of the font also. -- done, matt]] */ 

}

/* The lines in the LN3 file are limited to lengths of about
100 bytes. We keep track of how many bytes are written so
far in the global lnhp. The accounting is conservative, so
e.g. each integer representing a pixel position counts as 4
bytes even though it might be shorter. [[One could easily
increase 100 to 200. It is not clear what problems are
provoked by going over, say, 256.]] 

Vpset keeps track of whether the vertical position needs to
be output to the LN03 file before setting any more
characters. Hh_old keeps track of the horizontal position
which LN03 thinks it's at. */ 

GLOBAL int ln3p,vpset,hh_old;

#define inc_ln3p(x) ln3p += x; if (ln3p > 100) \
    { ln3p = 0; vpset = 0; hh_old = 30000; }

/* [[In the above macro, hh_old is set to 30000 to mean "a
very large number" (the maximum valid hh for an LN03 is
2550), so as to force the code below to re-output the true
hh. What are the implications of this kludge? Would it not
be more reasonable to have instead an hhset variable?]] */ 

/* A stack of hvxyzw values is kept; the stack pointer is
called s. [[Again, it would be better to make this stack a
linked list.]] */ 

#define STACKSIZE 100

GLOBAL long hstack[STACKSIZE], vstack[STACKSIZE], xstack[STACKSIZE], 
    ystack[STACKSIZE], zstack[STACKSIZE], wstack[STACKSIZE];
GLOBAL int hhstack[STACKSIZE], vvstack[STACKSIZE];
GLOBAL int s;

/* DVI files specify distances in units of 2^-16 points.
When translating to a device-specific format, it is
necessary to round the DVI distances to pixel units. This is
done by means of the pixel_round macro. 

However, rather than using this macro in the straightforward
way, rounding is often performed by more elaborate
techniques, which we call "Stanford rules" (after John Le
Carre's "Moscow rules"). These rules make use of a parameter
MAX_DRIFT, which is roughly the maximum number of pixels
that things are allowed to deviate from straightforward
rounding. */ 

#define pixel_round(x) ((int) ((x<0) ? \
    (conv*(x)-0.5) : (conv*(x)+0.5)))
    
#define MAX_DRIFT 2

/* Pass2 reads the dvi file and interprets the commands in
it, usually by calling other routines. The interpretation
generally consists of writing something into the output
file, updating the current fonts and positions, and possibly
updating the stack. */ 

int pass2()
{
    int i,j;
    long int p;
    unsigned int k;
    
    if (read_preamble() != 0) {
	fprintf(stderr,bad_DVI_message);
	return(1);
    }

    curf = 0;
    ln3p = 0;
    s = 0;
    vpset = 0;
    hh_old = 30000;

/* Skip pages until the desired starting page is reached. A
nonzero value is returned if the starting page is never
encountered. */ 

    if (skip_pages() != 0) return(0); 

    for (;;) {
	if (dvieof) { 
            fprintf(stderr,bad_DVI_message);
	    return(1); }
	k = mygetcdvi;
	if (k == post) return(0);
	if (k >= undefined_command) {
            fprintf(stderr,bad_DVI_message);
	    return(1); }
	
	if (k >= set_char_0 && k < set_char_0+128) {
	    p = k;
	    k = set1;
        } else if (k >= fnt_num_0 && k < fnt_num_0+64) {
	    p = k-fnt_num_0;
	    k = fnt1;
        } else p = first_par(k);

	j = do_command(k,p);
	if (j == 2) return(0); /* done with the required number of pages */
	else if (j == 1) return(1); /* error encountered, stop */

    }
}

GLOBAL long first_counter;

/* Read from the DVI file until the starting page condition
is met. Return 1 if something goes wrong, or if the DVI file
comes to an end. This function is copied quite closely from
DVItype. */ 

int skip_pages() {

    unsigned int k;
    int i;
    long p;
    char startp;
    
    for (;;) {
	if (dvieof) return(1);
	k = mygetcdvi;
	if (k == post) return(1);
	if (k >= set_char_0 && k < set_char_0+128) {
	    p = k;
	    k = set1;
        } else if (k >= fnt_num_0 && k < fnt_num_0+64) {
	    p = k-fnt_num_0;
	    k = fnt1;
        } else p = first_par(k);

	switch (k) {
	    case bop:
		startp = 1;
		for (i=0; i<10; i++) {
		    four_bytes;
		    if (i == 0) first_counter = lcx.l;
		    if (i < how_many_counts && use_count[i] &&
			    lcx.l != start_page[i]) startp = 0;
		    }
		four_bytes;
		if (startp != 0) { 
		    v = 0; vv = 0; h = 0; hh = 0;
		    printf("\n [%ld]",first_counter);
		    num_pages = 1; return(0); }
		break;
	    case set_rule:
	    case put_rule:
		four_bytes;
	        break;
	    four_cases(fnt_def1)
		define_font_pass2(p);
		break;
	    four_cases(xxx1)
		for (; p>0; p--) mygetcdvi;
		break;
            default:
		break;
	}
    }
/*  return(0); /* Unreachable */
}

/* Do_command performs the DVI command of code k, assuming
the "first parameter" is p. It is assumed that k is not one
of set_char0 through set_char127. */ 

int do_command(k,p)
int k;
long p;
{
    int i,j,l,lnf;

    switch (k) {
	four_cases(fnt_def1)
	    define_font_pass2();
	    break;

/* It is possible that the dvi file sets some glyphs off the
page. No error message is given, since the user will
generally see what is happening in the output (plus, if
Ln03DVI gives an error message, users will complain about
Ln03DVI even though the error is in their TeX file). 

In most cases, Ln03DVI takes no special action at all, since
the LN03 will clip the glyphs for us. Unfortunately, the
LN03 doesn't let us specify negative horizontal or vertical
positions, so we have to clip glyphs at such positions away
ourselves. Also, if one sets at a position below the bottom
margin, the LN03 will eject a page, so glyphs that are set
below that margin also have to be clipped by hand. 

The following code accomplishes that: */ 

	four_cases(put1)
	four_cases(set1)

	    if (vv+voff > 0 && vv+voff <= maxbmar && hh+hoff > 0) {
		if (!vpset) {
		    fprintf(outfile,"\n\033[%dd",vv+voff);
		    fprintf(outfile,"\033[%d`",hh+hoff);
		    ln3p = 16;
		    vpset = 1;
		    hh_old = hh;
		}
		if (hh_old != hh) {
		    if (hh > hh_old) fprintf(outfile,"\033[%da",hh-hh_old);
		    else fprintf(outfile,"\033[%d`",hh+hoff);
		    ln3p += 7;
		}

#ifndef SEVENBIT
		putc(curchu[p],outfile);
#else 
		if (curchu[p] > 127) {
		    if (right7 == 0) {
			fputs("\033n",outfile);
			inc_ln3p(2);
			right7 = 1;
		    }
		    putc(curchu[p]-128,outfile);
		} else {
		    if (right7 == 1) {
		        putc(15,outfile);
			inc_ln3p(1);
			right7 = 0;
		    }
		    putc(curchu[p],outfile);
		}
#endif
		inc_ln3p(1);
	    }
	    if (k >= put1) {
	        hh_old = hh+chw[txf2lnf[curf]][curchu[p]];
		break;
	    }
	    h += font_width[curf][p];

/* In rounding h to generate the pixel-position hh, Stanford
rules (see above) come into play. We set the new hh
(horizontal position in pixels) to the value obtained by
adding the pixel width of the character being set to the
current position. We then correct this value so that it does
not exceed the rounded version of the true position by more
than MAX_DRIFT pixels. 

Note that if we did not apply Stanford rules here, or
equivalently if we set MAX_DRIFT to zero, many more
set-X-position commands would appear in the output. */ 

	    hh += chw[txf2lnf[curf]][curchu[p]];
	    hh_old = hh;
	    l = pixel_round(h);
	    if (hh-l > MAX_DRIFT) hh = l+MAX_DRIFT;
	    else if (l-hh > MAX_DRIFT) hh = l-MAX_DRIFT;
	    break;

	four_cases(fnt1)
	    set_curf(p);
	    curchu = &(txfa[curf] -> chu[0]);
	    lnf = txf2lnf[curf];
	    if (useno[lnf] == -1) {
		useno[whouses[maxfontnos]] = -1;
		useno[lnf] = maxfontnos;
		whouses[maxfontnos] = lnf;
		fprintf(outfile,"\033P1;1%d}%16s\033\\",maxfontnos,
			fname[lnf]);
		inc_ln3p(26);
	    }
	    fprintf(outfile,"\033[1%dm",useno[lnf]);
	    inc_ln3p(5);
	    break;

	case set_rule:
	case put_rule: 

/* When converting rule dimensions to pixel dimensions, we
do not follow Stanford rules. Rather, we just round the true
positions to obtain the pixel positions. This avoids
unsightly gaps between rules. [[It should not cause much of
a problem with typical rule applications (ruled tables,
fraction bars)...but perhaps with large delimiters there
might be some difficulty. This needs more thought...]] */ 

	    four_bytes; 
	    if (p >= 0 && lcx.l >= 0) {
	        i = pixel_round(p);
		j = pixel_round(lcx.l);
                if (p > 0 && i == 0) i = 1;
                if (lcx.l > 0 && j == 0) j = 1;
		do_rule(pixel_round(h),
			pixel_round(v)-i,pixel_round(h)+j,
			pixel_round(v));
            }
	    if (k == set_rule) {
		h += lcx.l;
		hh = pixel_round(h);
	    }
	    break;

	 case push:
	    s++;
	    if (s == STACKSIZE) {
		fprintf(stderr,"\nStack too deep for Ln03DVI\n");
		return(1);
	    }
	    xstack[s] = x;
	    ystack[s] = y;
	    vstack[s] = v;
	    hstack[s] = h;
	    vvstack[s] = vv;
	    hhstack[s] = hh;
	    wstack[s] = w;
	    zstack[s] = z;
	    break;

	case pop:
	    if (s == 0) {
		fprintf(stderr,bad_DVI_message); 
		return(1); 
	    }
	    if (vv != vvstack[s]) vpset = 0;
	    x = xstack[s]; 
	    y = ystack[s];    
	    v = vstack[s]; 
	    h = hstack[s];    
	    vv = vvstack[s]; 
	    hh = hhstack[s];    
	    w = wstack[s]; 
	    z = zstack[s];
	    s--; 
	    break; 

	four_cases(xxx1)
	    do_special_pass2(p);
	    break;

	case bop:

/* If we've done the required number of pages, we'll skip
the rest of the DVI file. If not, type the first parameter
of bop on the user's terminal the way TeX does, to give an
indication of progress. */ 

	    if (num_pages == max_pages) return(2);
	    v = 0; vv = 0; h = 0; hh = 0;
	    vpset = 0; hh_old = 100000;
	    four_bytes;
	    if (num_pages%12 == 0) printf("\n");
	    first_counter = lcx.l;
	    printf(" [%ld]",lcx.l);
	    fflush(stdout);
	    num_pages++;
	    for (i = 0; i<40; i++) mygetcdvi; 
	    break;

	case eop:
	    fprintf(outfile,"\n\f");
	    ln3p = 0;
	    break;

/* Now we have to consider the cases for pure motion. */ 

	four_cases(right1)
	    set_h(h+p);
	    break;
	four_cases(x1)
	    x = p;
	case x0:
	    set_h(h+x);
	    break;
	four_cases(y1)
	    y = p;
	case y0:
	    set_v(v+y);
	    break;
	four_cases(w1)
	    w = p;
	case w0:
	    set_h(h+w);
	    break;
	four_cases(z1)
	    z = p;
	case z0:
	    set_v(v+z);
	    break;
	four_cases(down1)
	    set_v(v+p);
	    break;

    }	
    return(0);
}

/* Set_curf sets the current font to external number p. Note
that the current font is maintained as an internal font
number. */ 

int set_curf(p)
int p;
{
    to_ext[nf] = p;
    curf = 0;
    while (to_ext[curf] != p) { curf++; }    
}

/* Define_font processes a font definition from the DVI
file. The TFM file for the font is read at this point from
the directory TEX$FONTS.

[[Originally it made sense to read the DVI files here,
because we were supporting the LN03 font file format only,
and that has no place for the tfm widths. The PXL and PK
formats, on the other hand, contain the widths, so that if
those files are being used there is no need to open the TFM
file at all. Hence, this code should all be moved to after
we've figured out what kind of raster file is being used.]]
*/ 

int define_font(e)
int e;
{
    int i;
    unsigned char p,n;
    if (e == MAXTEXFONTS) { fprintf(stderr,"\nToo many fonts for Ln03DVI\n");
	return(1); }
    txfa[nf] = (struct txf *)malloc(sizeof(struct txf));
    to_ext[nf] = e;
    four_bytes;
    four_bytes;
    txfa[nf] -> scaled_size = lcx.l;
    four_bytes;
    txfa[nf] -> design_size = lcx.l;
    for (i=0; i<256; i++) txfa[nf] -> chu[i] = '\0';
    p = mygetcdvi; n = mygetcdvi;
    font_name[nf] = malloc(p+n+1);
    for (i=0; i<p+n; i++) { font_name[nf][i] = mygetcdvi; }
    font_name[nf][p+n] = '\0';

    if (txfa[nf] -> scaled_size <= 0 || txfa[nf] -> scaled_size >=
	8*8*8*8*8*8*8*8*8) {
	fprintf(stderr,"\n Font %s has a bad scaled size\n",font_name[nf]);
	return(1);
    }
    if (txfa[nf] -> design_size <= 0 || txfa[nf] -> design_size >= 
	8*8*8*8*8*8*8*8*8) {
	fprintf(stderr,"\n Font %s has a bad design size\n",font_name[nf]);
	return(1);
    }

/* We follow DVItype and compute for each font a "space"
parameter which is one-sixth of the scaled design size. This
parameter is used in rounding the horizontal position to
pixels according to "Stanford rules." See the function set_h
below. */ 

    txfa[nf] -> space = txfa[nf] -> scaled_size/6;     

    i = read_tfm_file();
    if (i != 0) return(i);
    nf++;
    return(0); 

}

/* TFM files, like the DVI file, are read with getc, foolish
as that may seem. We use the same overlays that are used for
merging DVI bytes into longwords. However, since the TFM
file consists of longwords, only tfm_longword is need. */ 

#define tfm_longword { lcx.uc[3] = getc(tfmfile); \
    lcx.uc[2] = getc(tfmfile); lcx.uc[1] = getc(tfmfile); \
    lcx.uc[0] = getc(tfmfile); }

/* Read_tfm_file obtains the character widths from the TFM file
corresponding to font nf. */ 

int read_tfm_file() {

    int i,lh,nw;
    int info[256];
    long z,alpha,beta;
    long width[256];

    open_tfm_file();
    if (tfmfile == NULL) {
	fprintf(stderr,"\n Can't open TFM file for font ");
	perror(font_name[nf]);
	return(1); }

/* The TFM format is described in some issue of the TUGBoat
(TeX users' group newsletter), and in the comments to the
programs TeX and TFtoPL. Here we summarize those aspects of
TFM format that are relevant to the task of extracting the
widths of the characters. 

The first 24 bytes of a TFM file contain twelve 16-bit
integers that give the lengths of the various subsequent
portions of the file. The ones relevant to our purposes are
LH, length of the header data, BC, the smallest character
code in the font, EC, the largest character code in the
font, and NW, number of words in the width table. So, we
read those right now, and then skip over the remainder, and
then over a set of LH longwords called the "header." */ 

    tfm_longword; 
    lh = 256*lcx.uc[1] + lcx.uc[0];
    tfm_longword;
    txfa[nf] -> bc = 256*lcx.uc[3] + lcx.uc[2];
    txfa[nf] -> ec = 256*lcx.uc[1] + lcx.uc[0];
    tfm_longword;
    nw = 256*lcx.uc[3] + lcx.uc[2];
    if (txfa[nf] -> bc > 255 || txfa[nf] -> ec > 255 ||
	txfa[nf] -> bc > txfa[nf] -> ec || nw > 256) {
	fprintf(stderr,"\n Bad TFM file for font %s\n",font_name[nf]);
	return(1);
    }

    for(i=0; i<lh+3; i++) tfm_longword;

/* After the header, there are two arrays in the TFM file
that interest us. The first, INFO, is EC-BC+1 longwords long
and contains pointers to the second, WIDTH, which is NW
longwords long. For each character i, the width of i is
WIDTH[INFO[i-BC]]. We read these arrays into memory. */ 

    for(i=0; i<txfa[nf] -> ec-txfa[nf] -> bc+1; i++) {
	tfm_longword;
	if (lcx.uc[3] >= nw) {
	    printf("\n Bad TFM file for font %s",font_name[nf]);
	    return(1);
	}
	info[i] = lcx.uc[3];
    }

/* The widths are stored in a rather strange format known as
a "fix-word." A nonnegative width is expressed in "fix-word"
format by expressing it in units of 2^-20 times the design
size. A negative width is expressed in "fix-word" format by
expressing its negative in those units, and then changing
the most significant byte to 255. 

One needs to convert these widths into DVI units,
multiplying by the scaled design size according to a certain
arcane algorithm. The algorithm is copied from DVItype, to
which we refer the reader for an explanation. [[Copout. I
don't really understand what's going on here. Why not just
use floating point? That's what it's for.]] */ 

    z = txfa[nf] -> scaled_size;
    alpha = 16*z; beta = 16;
    while (z >= 4*(8*8*8*8*8*8*8)) { z = z/2; beta = beta/2; }
    for(i=0; i<nw; i++) {
	tfm_longword;
	width[i] = ( ( (lcx.uc[0]*z)/256 + lcx.uc[1]*z )/256  + 
		lcx.uc[2]*z)/beta;
	if (lcx.uc[3] == 255) width[i] -= alpha;
    }

    fclose(tfmfile);

/* Using these two arrays, we now compute the widths of the
characters in the fonts and place them into two malloc'ed
arrays, one for the widths in DVI units, one for the width
in pixel units. */ 

    font_width[nf] = (long int *)malloc(4*(txfa[nf] -> ec+1));
    
    for (i=0; i<txfa[nf] -> bc; i++) font_width[nf][i] = 0;
    for (i=txfa[nf] -> bc; i <= txfa[nf] -> ec; i++) 
	font_width[nf][i] = width[info[i-txfa[nf] -> bc]];
    return(0);
}

/* Open_tfm_file finds and opens the tfm file corresponding
to a font nf. The global file variable tfmfile is used to
hold the file pointer. [[This function will not work if the
TFM file lies over the net on a VMS V3.x host, because C
file opens do not work in such circumstances. The problem
can be ignored, because eventually there should be very few
VMS V3.x hosts left.]] */ 

int open_tfm_file () {

    int jext,jnam;
    char filespec[FILESPECLEN];

#ifndef vms
    char *texfontdir;
#endif


    find_filename(font_name[nf],&jnam,&jext);
    filespec[0] = '\0';

/* If there is no directory part, fill in using the logical
tex$fonts */ 

#ifdef vms
    if (jnam == 0) strcpy(filespec,"tex$fonts:");
#else
    if (jnam == 0) { 
	texfontdir = getenv("TEXFONTS");
	if  (texfontdir == NULL)
	    texfontdir = "/usr/lib/tex/fonts";
	strcpy(filespec,texfontdir);
	if  (filespec[strlen(filespec)-1] != '/')
	    strcat(filespec,"/");
    }
#endif
    strcat(filespec,font_name[nf]);

/* if there is no extension, add the extension ".tfm" */

    if (font_name[nf][jext] == '\0') strcat(filespec,".tfm");
    tfmfile = fopen(filespec,"r");

}

/* Define_font_pass2 skips a font definition from the DVI
file. */ 

int define_font_pass2()
{
    unsigned char p,n;
    int i;
    four_bytes;
    four_bytes;
    four_bytes;
    p = mygetcdvi; n = mygetcdvi;
    for (i=0; i<p+n; i++) mygetcdvi;
}

/* Do_rule writes into the ln3 file the escape sequence
corresponding to a rule. The rule is silently clipped to fit
on the page. */ 

int do_rule(xx0,yy0,xx1,yy1) 
int xx0,yy0,xx1,yy1;
{
    int j;

    xx0 = min(xx0+hoff,maxrmar);
    xx1 = min(xx1+hoff,maxrmar);
    xx0 = max(xx0,0);
    xx1 = max(xx1,0);
    yy0 = min(yy0+voff,maxbmar);
    yy1 = min(yy1+voff,maxbmar);
    yy0 = max(yy0,0);
    yy1 = max(yy1,0);
    if (xx0 > xx1) { j = xx0; xx0 = xx1; xx1 = j; }
    if (yy0 > yy1) { j = yy0; yy0 = yy1; yy1 = j; }
	    
    if ((yy1 != yy0 && xx1 != xx0)) {
	fprintf(outfile,"\033[1;%d;%d;%d;%d!|",
	    xx0,yy0,yy1-yy0,xx1-xx0);
	inc_ln3p(25);
    }
}

/* Set_v is called to execute vertical-position-altering
commands, other than pops. It modifies v and vv, and outputs
the vertical position to the LN3 file. We don't follow
Stanford rules here. They sometimes set the vertical
position in pixels vv to something other than the rounded
value of v. Not following Stanford rules implies, for
example, that the relative vertical positions of an accent
and its accentee may differ by one pixel according to how
the baseline of the accentee gets rounded. [[This should
perhaps be fixed.]] */ 

int set_v(v1)
int v1;
{
    int l;

    l = pixel_round(v1);
    v = v1;
    vv = l;
    vpset = 0;
}    

/* Set_h is called whenever a DVI command is encountered
that alters the horizonal position, other than a set_char,
set_rule or pop. It sets h to the new value, and alters hh
according to Stanford rules. */ 

int set_h(new_h)
int new_h;   
{
    int l,old_hh;

    old_hh = hh;
    l = pixel_round(new_h);
    if (txfa[curf] == 0 || new_h-h >= txfa[curf] -> space
	|| new_h-h <= -4*txfa[curf] -> space) hh = l;
    else {
	hh += pixel_round(new_h-h);
	if (hh-l > MAX_DRIFT) hh = l+MAX_DRIFT;
	else if (hh-l < -MAX_DRIFT) hh = l-MAX_DRIFT;
    }
    h = new_h;
    return(0);
}