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/*
* xvgifwr.c - handles writing of GIF files. based on flgife.c and
* flgifc.c from the FBM Library, by Michael Maudlin
*
* Contains:
* WriteGIF(fp, pic, ptype, w, h, rmap, gmap, bmap, numcols, colorstyle,
* comment)
*
* Note: slightly brain-damaged, in that it'll only write non-interlaced
* GIF files (in the interests of speed, or something)
*
*/
/*****************************************************************
* Portions of this code Copyright (C) 1989 by Michael Mauldin.
* Permission is granted to use this file in whole or in
* part for any purpose, educational, recreational or commercial,
* provided that this copyright notice is retained unchanged.
* This software is available to all free of charge by anonymous
* FTP and in the UUNET archives.
*
*
* Authors: Michael Mauldin (mlm@cs.cmu.edu)
* David Rowley (mgardi@watdcsu.waterloo.edu)
*
* Based on: compress.c - File compression ala IEEE Computer, June 1984.
*
* Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
* Jim McKie (decvax!mcvax!jim)
* Steve Davies (decvax!vax135!petsd!peora!srd)
* Ken Turkowski (decvax!decwrl!turtlevax!ken)
* James A. Woods (decvax!ihnp4!ames!jaw)
* Joe Orost (decvax!vax135!petsd!joe)
*****************************************************************/
/* Copyright Notice
* ================
* Copyright 1989, 1990, 1991, 1992, 1993 by John Bradley
*
* Permission to use, copy, and distribute XV in its entirety, for
* non-commercial purposes, is hereby granted without fee, provided that
* this license information and copyright notice appear in all copies.
*
* Note that distributing XV 'bundled' in with ANY product is considered
* to be a 'commercial purpose'.
*
* Also note that any copies of XV that are distributed MUST be built
* and/or configured to be in their 'unregistered copy' mode, so that it
* is made obvious to the user that XV is shareware, and that they should
* consider donating, or at least reading this License Info.
*
* The software may be modified for your own purposes, but modified
* versions may NOT be distributed without prior consent of the author.
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the author be held liable for any damages
* arising from the use of this software.
*
* If you would like to do something with XV that this copyright
* prohibits (such as distributing it with a commercial product,
* using portions of the source in some other program, etc.), please
* contact the author (preferably via email). Arrangements can
* probably be worked out.
*
* XV is shareware for PERSONAL USE only. You may use XV for your own
* amusement, and if you find it nifty, useful, generally cool, or of
* some value to you, your non-deductable donation would be greatly
* appreciated. $25 is the suggested donation, though, of course,
* larger donations are quite welcome. Folks who donate $25 or more
* can receive a Real Nice bound copy of the XV manual for no extra
* charge.
*
* Commercial, government, and institutional users MUST register their
* copies of XV, for the exceedingly REASONABLE price of just $25 per
* workstation/X terminal. Site licenses are available for those who
* wish to run XV on a large number of machines. Contact the author
* for more details.
*
* The author may be contacted via:
* US Mail: John Bradley
* 1053 Floyd Terrace
* Bryn Mawr, PA 19010
*
* Phone: (215) 898-8813
* EMail: bradley@cis.upenn.edu
*/
#include "xv.h"
typedef long int count_int;
static int Width, Height;
static int curx, cury;
static long CountDown;
static int Interlace;
static byte bw[2] = {0, 0xff};
#ifdef __STDC__
static void putword(int, FILE *);
static void compress(int, FILE *, byte *, int);
static void output(int);
static void cl_block(void);
static void cl_hash(count_int);
static void char_init(void);
static void char_out(int);
static void flush_char(void);
#else
static void putword(), compress(), output(), cl_block(), cl_hash();
static void char_init(), char_out(), flush_char();
#endif
static byte pc2nc[256],r1[256],g1[256],b1[256];
/*************************************************************/
int WriteGIF(fp, pic, ptype, w, h, rmap, gmap, bmap, numcols, colorstyle,
comment)
FILE *fp;
byte *pic;
int ptype, w,h;
byte *rmap, *gmap, *bmap;
int numcols, colorstyle;
char *comment;
{
int RWidth, RHeight;
int LeftOfs, TopOfs;
int ColorMapSize, InitCodeSize, Background, BitsPerPixel;
int i,j,nc;
byte *pic8;
byte rtemp[256],gtemp[256],btemp[256];
if (ptype == PIC24) { /* have to quantize down to 8 bits */
pic8 = Conv24to8(pic, w, h, 256, rtemp,gtemp,btemp);
if (!pic8) FatalError("Unable to malloc in WriteGIF()");
rmap = rtemp; gmap = gtemp; bmap = btemp; numcols=256;
}
else pic8 = pic;
/* if writing B/W stipple... */
if (colorstyle==2) {
rmap = gmap = bmap = bw;
numcols = 2;
}
Interlace = 0;
Background = 0;
for (i=0; i<256; i++) { pc2nc[i] = r1[i] = g1[i] = b1[i] = 0; }
/* compute number of unique colors */
nc = 0;
for (i=0; i<numcols; i++) {
/* see if color #i is already used */
for (j=0; j<i; j++) {
if (rmap[i] == rmap[j] && gmap[i] == gmap[j] &&
bmap[i] == bmap[j]) break;
}
if (j==i) { /* wasn't found */
pc2nc[i] = nc;
r1[nc] = rmap[i];
g1[nc] = gmap[i];
b1[nc] = bmap[i];
nc++;
}
else pc2nc[i] = pc2nc[j];
}
/* figure out 'BitsPerPixel' */
for (i=1; i<8; i++)
if ( (1<<i) >= nc) break;
BitsPerPixel = i;
ColorMapSize = 1 << BitsPerPixel;
RWidth = Width = w;
RHeight = Height = h;
LeftOfs = TopOfs = 0;
CountDown = w * h; /* # of pixels we'll be doing */
if (BitsPerPixel <= 1) InitCodeSize = 2;
else InitCodeSize = BitsPerPixel;
curx = cury = 0;
if (!fp) {
fprintf(stderr, "WriteGIF: file not open for writing\n" );
if (ptype == PIC24) free(pic8);
return (1);
}
if (DEBUG)
fprintf(stderr,"WrGIF: pic=%x, w,h=%dx%d, numcols=%d, Bits%d,Cmap=%d\n",
pic8, w,h,numcols,BitsPerPixel,ColorMapSize);
if (comment && strlen(comment)>0)
fwrite("GIF89a", 1, 6, fp); /* the GIF magic number */
else
fwrite("GIF87a", 1, 6, fp); /* the GIF magic number */
putword(RWidth, fp); /* screen descriptor */
putword(RHeight, fp);
i = 0x80; /* Yes, there is a color map */
i |= (8-1)<<4; /* OR in the color resolution (hardwired 8) */
i |= (BitsPerPixel - 1); /* OR in the # of bits per pixel */
fputc(i,fp);
fputc(Background, fp); /* background color */
fputc(0, fp); /* future expansion byte */
if (colorstyle == 1) { /* greyscale */
for (i=0; i<ColorMapSize; i++) {
j = MONO(r1[i], g1[i], b1[i]);
fputc(j, fp);
fputc(j, fp);
fputc(j, fp);
}
}
else {
for (i=0; i<ColorMapSize; i++) { /* write out Global colormap */
fputc(r1[i], fp);
fputc(g1[i], fp);
fputc(b1[i], fp);
}
}
if (comment && strlen(comment)>0) { /* write comment blocks */
char *sp;
int i, blen;
fputc(0x21, fp); /* EXTENSION block */
fputc(0xFE, fp); /* comment extension */
sp = comment;
while ( (blen=strlen(sp)) > 0) {
if (blen>255) blen = 255;
fputc(blen, fp);
for (i=0; i<blen; i++, sp++) fputc(*sp, fp);
}
fputc(0, fp); /* zero-length data subblock to end extension */
}
fputc( ',', fp ); /* image separator */
/* Write the Image header */
putword(LeftOfs, fp);
putword(TopOfs, fp);
putword(Width, fp);
putword(Height, fp);
if (Interlace) fputc(0x40, fp); /* Use Global Colormap, maybe Interlace */
else fputc(0x00, fp);
fputc(InitCodeSize, fp);
compress(InitCodeSize+1, fp, pic8, w*h);
fputc(0,fp); /* Write out a Zero-length packet (EOF) */
fputc(';',fp); /* Write GIF file terminator */
if (ptype == PIC24) free(pic8);
if (ferror(fp)) return -1;
return (0);
}
/******************************/
static void putword(w, fp)
int w;
FILE *fp;
{
/* writes a 16-bit integer in GIF order (LSB first) */
fputc(w & 0xff, fp);
fputc((w>>8)&0xff, fp);
}
/***********************************************************************/
static unsigned long cur_accum = 0;
static int cur_bits = 0;
#define min(a,b) ((a>b) ? b : a)
#define XV_BITS 12 /* BITS was already defined on some systems */
#define MSDOS 1
#define HSIZE 5003 /* 80% occupancy */
typedef unsigned char char_type;
static int n_bits; /* number of bits/code */
static int maxbits = XV_BITS; /* user settable max # bits/code */
static int maxcode; /* maximum code, given n_bits */
static int maxmaxcode = 1 << XV_BITS; /* NEVER generate this */
#define MAXCODE(n_bits) ( (1 << (n_bits)) - 1)
static count_int htab [HSIZE];
static unsigned short codetab [HSIZE];
#define HashTabOf(i) htab[i]
#define CodeTabOf(i) codetab[i]
static int hsize = HSIZE; /* for dynamic table sizing */
/*
* To save much memory, we overlay the table used by compress() with those
* used by decompress(). The tab_prefix table is the same size and type
* as the codetab. The tab_suffix table needs 2**BITS characters. We
* get this from the beginning of htab. The output stack uses the rest
* of htab, and contains characters. There is plenty of room for any
* possible stack (stack used to be 8000 characters).
*/
#define tab_prefixof(i) CodeTabOf(i)
#define tab_suffixof(i) ((char_type *)(htab))[i]
#define de_stack ((char_type *)&tab_suffixof(1<<XV_BITS))
static int free_ent = 0; /* first unused entry */
/*
* block compression parameters -- after all codes are used up,
* and compression rate changes, start over.
*/
static int clear_flg = 0;
static long int in_count = 1; /* length of input */
static long int out_count = 0; /* # of codes output (for debugging) */
/*
* compress stdin to stdout
*
* Algorithm: use open addressing double hashing (no chaining) on the
* prefix code / next character combination. We do a variant of Knuth's
* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
* secondary probe. Here, the modular division first probe is gives way
* to a faster exclusive-or manipulation. Also do block compression with
* an adaptive reset, whereby the code table is cleared when the compression
* ratio decreases, but after the table fills. The variable-length output
* codes are re-sized at this point, and a special CLEAR code is generated
* for the decompressor. Late addition: construct the table according to
* file size for noticeable speed improvement on small files. Please direct
* questions about this implementation to ames!jaw.
*/
static int g_init_bits;
static FILE *g_outfile;
static int ClearCode;
static int EOFCode;
/********************************************************/
static void compress(init_bits, outfile, data, len)
int init_bits;
FILE *outfile;
byte *data;
int len;
{
register long fcode;
register int i = 0;
register int c;
register int ent;
register int disp;
register int hsize_reg;
register int hshift;
/*
* Set up the globals: g_init_bits - initial number of bits
* g_outfile - pointer to output file
*/
g_init_bits = init_bits;
g_outfile = outfile;
/* initialize 'compress' globals */
maxbits = XV_BITS;
maxmaxcode = 1<<XV_BITS;
xvbzero((char *) htab, sizeof(htab));
xvbzero((char *) codetab, sizeof(codetab));
hsize = HSIZE;
free_ent = 0;
clear_flg = 0;
in_count = 1;
out_count = 0;
cur_accum = 0;
cur_bits = 0;
/*
* Set up the necessary values
*/
out_count = 0;
clear_flg = 0;
in_count = 1;
maxcode = MAXCODE(n_bits = g_init_bits);
ClearCode = (1 << (init_bits - 1));
EOFCode = ClearCode + 1;
free_ent = ClearCode + 2;
char_init();
ent = pc2nc[*data++]; len--;
hshift = 0;
for ( fcode = (long) hsize; fcode < 65536L; fcode *= 2L )
hshift++;
hshift = 8 - hshift; /* set hash code range bound */
hsize_reg = hsize;
cl_hash( (count_int) hsize_reg); /* clear hash table */
output(ClearCode);
while (len) {
c = pc2nc[*data++]; len--;
in_count++;
fcode = (long) ( ( (long) c << maxbits) + ent);
i = (((int) c << hshift) ^ ent); /* xor hashing */
if ( HashTabOf (i) == fcode ) {
ent = CodeTabOf (i);
continue;
}
else if ( (long)HashTabOf (i) < 0 ) /* empty slot */
goto nomatch;
disp = hsize_reg - i; /* secondary hash (after G. Knott) */
if ( i == 0 )
disp = 1;
probe:
if ( (i -= disp) < 0 )
i += hsize_reg;
if ( HashTabOf (i) == fcode ) {
ent = CodeTabOf (i);
continue;
}
if ( (long)HashTabOf (i) >= 0 )
goto probe;
nomatch:
output(ent);
out_count++;
ent = c;
if ( free_ent < maxmaxcode ) {
CodeTabOf (i) = free_ent++; /* code -> hashtable */
HashTabOf (i) = fcode;
}
else
cl_block();
}
/* Put out the final code */
output(ent);
out_count++;
output(EOFCode);
}
/*****************************************************************
* TAG( output )
*
* Output the given code.
* Inputs:
* code: A n_bits-bit integer. If == -1, then EOF. This assumes
* that n_bits =< (long)wordsize - 1.
* Outputs:
* Outputs code to the file.
* Assumptions:
* Chars are 8 bits long.
* Algorithm:
* Maintain a BITS character long buffer (so that 8 codes will
* fit in it exactly). Use the VAX insv instruction to insert each
* code in turn. When the buffer fills up empty it and start over.
*/
static
unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
0x001F, 0x003F, 0x007F, 0x00FF,
0x01FF, 0x03FF, 0x07FF, 0x0FFF,
0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };
static void output(code)
int code;
{
cur_accum &= masks[cur_bits];
if (cur_bits > 0)
cur_accum |= ((long)code << cur_bits);
else
cur_accum = code;
cur_bits += n_bits;
while( cur_bits >= 8 ) {
char_out( (unsigned int) (cur_accum & 0xff) );
cur_accum >>= 8;
cur_bits -= 8;
}
/*
* If the next entry is going to be too big for the code size,
* then increase it, if possible.
*/
if (free_ent > maxcode || clear_flg) {
if( clear_flg ) {
maxcode = MAXCODE (n_bits = g_init_bits);
clear_flg = 0;
}
else {
n_bits++;
if ( n_bits == maxbits )
maxcode = maxmaxcode;
else
maxcode = MAXCODE(n_bits);
}
}
if( code == EOFCode ) {
/* At EOF, write the rest of the buffer */
while( cur_bits > 0 ) {
char_out( (unsigned int)(cur_accum & 0xff) );
cur_accum >>= 8;
cur_bits -= 8;
}
flush_char();
fflush( g_outfile );
#ifdef FOO
if( ferror( g_outfile ) )
FatalError("unable to write GIF file");
#endif
}
}
/********************************/
static void cl_block () /* table clear for block compress */
{
/* Clear out the hash table */
cl_hash ( (count_int) hsize );
free_ent = ClearCode + 2;
clear_flg = 1;
output(ClearCode);
}
/********************************/
static void cl_hash(hsize) /* reset code table */
register count_int hsize;
{
register count_int *htab_p = htab+hsize;
register long i;
register long m1 = -1;
i = hsize - 16;
do { /* might use Sys V memset(3) here */
*(htab_p-16) = m1;
*(htab_p-15) = m1;
*(htab_p-14) = m1;
*(htab_p-13) = m1;
*(htab_p-12) = m1;
*(htab_p-11) = m1;
*(htab_p-10) = m1;
*(htab_p-9) = m1;
*(htab_p-8) = m1;
*(htab_p-7) = m1;
*(htab_p-6) = m1;
*(htab_p-5) = m1;
*(htab_p-4) = m1;
*(htab_p-3) = m1;
*(htab_p-2) = m1;
*(htab_p-1) = m1;
htab_p -= 16;
} while ((i -= 16) >= 0);
for ( i += 16; i > 0; i-- )
*--htab_p = m1;
}
/******************************************************************************
*
* GIF Specific routines
*
******************************************************************************/
/*
* Number of characters so far in this 'packet'
*/
static int a_count;
/*
* Set up the 'byte output' routine
*/
static void char_init()
{
a_count = 0;
}
/*
* Define the storage for the packet accumulator
*/
static char accum[ 256 ];
/*
* Add a character to the end of the current packet, and if it is 254
* characters, flush the packet to disk.
*/
static void char_out(c)
int c;
{
accum[ a_count++ ] = c;
if( a_count >= 254 )
flush_char();
}
/*
* Flush the packet to disk, and reset the accumulator
*/
static void flush_char()
{
if( a_count > 0 ) {
fputc( a_count, g_outfile );
fwrite( accum, 1, a_count, g_outfile );
a_count = 0;
}
}
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