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/*
gifsave.c
gifsave.c is based on "ppmtogif" of Jef Poskanzer.
It is modified for ToyViewer.app by T. Ogihara. (1995)
*/
/* ppmtogif.c - read a portable pixmap and produce a GIF file
**
** Based on GIFENCOD by David Rowley <mgardi@watdscu.waterloo.edu>.A
** Lempel-Zim compression based on "compress".
**
** Copyright (C) 1989 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
**
** The Graphics Interchange Format(c) is the Copyright property of
** CompuServe Incorporated. GIF(sm) is a Service Mark property of
** CompuServe Incorporated.
*/
#include "../gif.h"
#include "../common.h"
#include "../strfunc.h"
#include "save.h"
#define MAXCOLORS 256
/*
* a code_int must be able to hold 2**BITS values of type int, and also -1
*/
typedef int code_int;
#ifdef SIGNED_COMPARE_SLOW
typedef unsigned long int count_int;
#else /*SIGNED_COMPARE_SLOW*/
typedef long int count_int;
#endif /*SIGNED_COMPARE_SLOW*/
static int GIFNextPixel(void);
static void compress( int init_bits, FILE* outfile );
static void init_output(void);
static void output( code_int code );
static void cl_block( void );
static void cl_hash( count_int hsize );
static void char_out( int c );
static void flush_char( void );
/*****************************************************************************
*
* GIFENCODE.C - GIF Image compression interface
*
* GIFEncode( FName, commonInfo, colornum, transp, interlace, palette )
*
*****************************************************************************/
static int Width, Height;
static int BitsPerPixel, alphaindex, isInterlaced;
static int yPtr, yPass;
static const char *comment;
static unsigned char **imageMap;
/*
* Return the next pixel from the image
*/
static int GIFNextPixel(void)
{
int eol, r, g, b, a;
if (yPtr < 0)
return EOF;
if ((eol = getPixel(&r, &g, &b, &a)) < 0) {
yPtr = -1;
return EOF;
}
if (isInterlaced & eol) {
yPtr += yPass ? (0x10 >> yPass) : 0x08;
if (yPtr >= Height) {
if (++yPass > 3)
yPtr = -1;
else
resetPixel(imageMap, (yPtr = 8 >> yPass));
}else
resetPixel(imageMap, yPtr);
}
if (alphaindex >= 0 && a == AlphaTransp)
return alphaindex;
return mapping(r, g, b);
}
void GIFEncode( FILE *fp, commonInfo *cinf, unsigned char **map,
int colornum, int transp, int interlace, paltype *palette )
{
int Resolution, ColorMapSize, InitCodeSize;
int i, j, power, n, B;
BOOL gif89;
isInterlaced = interlace;
resetPixel(imageMap = map, yPtr = 0);
yPass = 0;
alphaindex = transp;
comment = begin_comm(cinf->memo, YES);
n = colornum;
if (alphaindex && n < 256) n++;
for (i = 1, power = 0x02; i < 8; i++, power <<= 1)
if (power >= n) break;
BitsPerPixel = i;
ColorMapSize = 1 << BitsPerPixel;
Width = cinf->width;
Height = cinf->height;
Resolution = BitsPerPixel;
/* The initial code size */
InitCodeSize = ( BitsPerPixel <= 1 ) ? 2 : BitsPerPixel;
/* Write the Magic header */
gif89 = (alphaindex >= 0 || comment);
fprintf(fp, "%s", gif89 ? "GIF89a":"GIF87a");
/* Write out the screen width and height */
put_short( cinf->width, fp );
put_short( cinf->height, fp );
/* Indicate that there is a global colour map */
B = 0x80; /* Yes, there is a color map */
B |= (Resolution - 1) << 5; /* OR in the resolution */
B |= (BitsPerPixel - 1); /* OR in the Bits per Pixel */
fputc( B, fp );
/* Write out the Background colour */
fputc( 0, fp );
fputc( 0, fp ); /* Byte of 0's (future expansion) */
/* Write out the Global Colour Map */
n = (ColorMapSize < colornum) ? ColorMapSize : colornum;
for(i = 0; i < n; ++i ) {
unsigned char *p = palette[i];
for (j = 0; j < 3; j++)
fputc( p[j], fp );
}
for( ; i < ColorMapSize; ++i ) {
for (j = 0; j < 3; j++)
fputc( 255, fp ); /* stab */
}
if (gif89) {
if (alphaindex >= 0) {
fputc('!', fp); /* Extension */
fputc(0xf9, fp); /* Graphic Control Extension */
fputc(4, fp); /* Block Size */
fputc(TRANSPARENCY, fp);
fputc(0, fp);
fputc(0, fp); /* Delay Time */
fputc(alphaindex, fp); /* Transparent Color Index */
fputc(0, fp); /* Block Terminator */
}
if (comment == NULL)
comment = "by ToyViewer";
i = strlen(comment);
fputc('!', fp); /* Extension */
fputc(0xfe, fp); /* Comment Extension */
fputc(i, fp); /* Block Size */
fprintf(fp, "%s", comment);
fputc(0, fp); /* Block Terminator */
}
/* Write an Image separator */
fputc( ',', fp );
/* Write the Image header */
put_short( 0, fp ); /* LeftOfs */
put_short( 0, fp ); /* TopOfs */
put_short( Width, fp );
put_short( Height, fp );
/* No Local Color Table & Interlace Mode */
fputc( interlace ? 0x40 : 0x00, fp );
/* Write out the initial code size */
fputc( InitCodeSize, fp );
/*
* Go and actually compress the data
*/
compress( InitCodeSize+1, fp );
/* Write out a Zero-length packet (to end the series) */
fputc( 0, fp );
/* Write the GIF file terminator */
fputc( ';', fp );
}
/***************************************************************************
*
* GIFCOMPR.C - GIF Image compression routines
*
* Lempel-Ziv compression based on 'compress'. GIF modifications by
* David Rowley (mgardi@watdcsu.waterloo.edu)
*
***************************************************************************/
/*
* General DEFINEs
*/
#define BITS 12
#define HSIZE 5003 /* 80% occupancy */
/*
*
* GIF Image compression - modified 'compress'
*
* Based on: compress.c - File compression ala IEEE Computer, June 1984.
*
* By Authors: 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)
*/
#include <ctype.h>
static int n_bits; /* number of bits/code */
static int maxbits = BITS; /* user settable max # bits/code */
static code_int maxcode; /* maximum code, given n_bits */
static code_int maxmaxcode = (code_int)1 << BITS;
/* should NEVER generate this code */
#ifdef COMPATIBLE /* But wrong! */
# define MAXCODE(n_bits) ((code_int) 1 << (n_bits) - 1)
#else /*COMPATIBLE*/
# define MAXCODE(n_bits) (((code_int) 1 << (n_bits)) - 1)
#endif /*COMPATIBLE*/
static count_int htab [HSIZE];
static unsigned short codetab [HSIZE];
#define HashTabOf(i) htab[i]
#define CodeTabOf(i) codetab[i]
static code_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) ((unsigned char *)(htab))[i]
#define de_stack ((unsigned char *)&tab_suffixof((code_int)1<<BITS))
static code_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 int offset;
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( int init_bits, FILE *outfile )
{
long fcode;
code_int i /* = 0 */;
int c;
code_int ent;
code_int disp;
code_int hsize_reg;
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;
/*
* Set up the necessary values
*/
offset = 0;
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;
init_output(); /* Set up the 'byte output' routine */
ent = GIFNextPixel();
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( (code_int)ClearCode );
while ( (c = GIFNextPixel()) != EOF ) {
++in_count;
fcode = (long) (((long) c << maxbits) + ent);
i = (((code_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 ( (code_int) 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( (code_int)ent );
++out_count;
output( (code_int) EOFCode );
}
/*****************************************************************
* 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 cur_accum = 0;
static int cur_bits = 0;
static void output( code_int code )
{
static unsigned long masks[] = {
0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
0x001F, 0x003F, 0x007F, 0x00FF,
0x01FF, 0x03FF, 0x07FF, 0x0FFF,
0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };
if( cur_bits > 0 ) {
cur_accum &= masks[ cur_bits ];
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;
maxcode = ( n_bits == maxbits )
? maxmaxcode : 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 );
/* if( ferror( g_outfile ) ) writeerr(); */
}
}
/*
* Clear out the hash table
*/
static void cl_block(void) /* table clear for block compress */
{
cl_hash ( (count_int) hsize );
free_ent = ClearCode + 2;
clear_flg = 1;
output( (code_int)ClearCode );
}
static void cl_hash(count_int hsize) /* reset code table */
{
count_int *htab_p = htab+hsize;
long i;
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
*
****************************************************************************/
static int a_count; /* Number of characters so far in this 'packet' */
static char accum[256]; /* Define the storage for the packet accumulator */
static void init_output(void)
{
cur_accum = 0;
cur_bits = 0;
a_count = 0;
}
/*
* 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( 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( void )
{
if( a_count > 0 ) {
fputc( a_count, g_outfile );
fwrite( accum, 1, a_count, g_outfile );
a_count = 0;
}
}
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