/*
* rdgif.c
*
* Copyright (C) 1991-1996, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
**************************************************************************
* WARNING: You will need an LZW patent license from Unisys in order to *
* use this file legally in any commercial or shareware application. *
**************************************************************************
*
* This file contains routines to read input images in GIF format.
*
* These routines may need modification for non-Unix environments or
* specialized applications. As they stand, they assume input from
* an ordinary stdio stream. They further assume that reading begins
* at the start of the file; input_init may need work if the
* user interface has already read some data (e.g., to determine that
* the file is indeed GIF format).
*/
/*
* This code is loosely based on giftoppm from the PBMPLUS distribution
* of Feb. 1991. That file contains the following copyright notice:
* +-------------------------------------------------------------------+
* | Copyright 1990, David Koblas. |
* | 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. |
* +-------------------------------------------------------------------+
*
* We are also required to state that
* "The Graphics Interchange Format(c) is the Copyright property of
* CompuServe Incorporated. GIF(sm) is a Service Mark property of
* CompuServe Incorporated."
*/
#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
#ifdef GIF_SUPPORTED
#define MAXCOLORMAPSIZE 256 /* max # of colors in a GIF colormap */
#define NUMCOLORS 3 /* # of colors */
#define CM_RED 0 /* color component numbers */
#define CM_GREEN 1
#define CM_BLUE 2
#define MAX_LZW_BITS 12 /* maximum LZW code size */
#define LZW_TABLE_SIZE (1<<MAX_LZW_BITS) /* # of possible LZW symbols */
/* Macros for extracting header data --- note we assume chars may be signed */
#define LM_to_uint(a,b) ((((b)&0xFF) << 8) | ((a)&0xFF))
#define BitSet(byte, bit) ((byte) & (bit))
#define INTERLACE 0x40 /* mask for bit signifying interlaced image */
#define COLORMAPFLAG 0x80 /* mask for bit signifying colormap presence */
#define ReadOK(file,buffer,len) (JFREAD(file,buffer,len) == ((size_t) (len)))
/* LZW decompression tables look like this:
* symbol_head[K] = prefix symbol of any LZW symbol K (0..LZW_TABLE_SIZE-1)
* symbol_tail[K] = suffix byte of any LZW symbol K (0..LZW_TABLE_SIZE-1)
* Note that entries 0..end_code of the above tables are not used,
* since those symbols represent raw bytes or special codes.
*
* The stack represents the not-yet-used expansion of the last LZW symbol.
* In the worst case, a symbol could expand to as many bytes as there are
* LZW symbols, so we allocate LZW_TABLE_SIZE bytes for the stack.
* (This is conservative since that number includes the raw-byte symbols.)
*
* The tables are allocated from FAR heap space since they would use up
* rather a lot of the near data space in a PC.
*/
/* Private version of data source object */
typedef struct {
struct cjpeg_source_struct pub; /* public fields */
j_compress_ptr cinfo; /* back link saves passing separate parm */
JSAMPARRAY colormap; /* GIF colormap (converted to my format) */
/* State for GetCode and LZWReadByte */
char code_buf[256+4]; /* current input data block */
int last_byte; /* # of bytes in code_buf */
int last_bit; /* # of bits in code_buf */
int cur_bit; /* next bit index to read */
boolean out_of_blocks; /* TRUE if hit terminator data block */
int input_code_size; /* codesize given in GIF file */
int clear_code,end_code; /* values for Clear and End codes */
int code_size; /* current actual code size */
int limit_code; /* 2^code_size */
int max_code; /* first unused code value */
boolean first_time; /* flags first call to LZWReadByte */
/* Private state for LZWReadByte */
int oldcode; /* previous LZW symbol */
int firstcode; /* first byte of oldcode's expansion */
/* LZW symbol table and expansion stack */
UINT16 FAR *symbol_head; /* => table of prefix symbols */
UINT8 FAR *symbol_tail; /* => table of suffix bytes */
UINT8 FAR *symbol_stack; /* => stack for symbol expansions */
UINT8 FAR *sp; /* stack pointer */
/* State for interlaced image processing */
boolean is_interlaced; /* TRUE if have interlaced image */
jvirt_sarray_ptr interlaced_image; /* full image in interlaced order */
JDIMENSION cur_row_number; /* need to know actual row number */
JDIMENSION pass2_offset; /* # of pixel rows in pass 1 */
JDIMENSION pass3_offset; /* # of pixel rows in passes 1&2 */
JDIMENSION pass4_offset; /* # of pixel rows in passes 1,2,3 */
} gif_source_struct;
typedef gif_source_struct * gif_source_ptr;
/* Forward declarations */
METHODDEF(JDIMENSION) get_pixel_rows
JPP((j_compress_ptr cinfo, cjpeg_source_ptr sinfo));
METHODDEF(JDIMENSION) load_interlaced_image
JPP((j_compress_ptr cinfo, cjpeg_source_ptr sinfo));
METHODDEF(JDIMENSION) get_interlaced_row
JPP((j_compress_ptr cinfo, cjpeg_source_ptr sinfo));
LOCAL(int)
ReadByte (gif_source_ptr sinfo)
/* Read next byte from GIF file */
{
register FILE * infile = sinfo->pub.input_file;
int c;
if ((c = getc(infile)) == EOF)
ERREXIT(sinfo->cinfo, JERR_INPUT_EOF);
return c;
}
LOCAL(int)
GetDataBlock (gif_source_ptr sinfo, char *buf)
/* Read a GIF data block, which has a leading count byte */
/* A zero-length block marks the end of a data block sequence */
{
int count;
count = ReadByte(sinfo);
if (count > 0) {
if (! ReadOK(sinfo->pub.input_file, buf, count))
ERREXIT(sinfo->cinfo, JERR_INPUT_EOF);
}
return count;
}
LOCAL(void)
SkipDataBlocks (gif_source_ptr sinfo)
/* Skip a series of data blocks, until a block terminator is found */
{
char buf[256];
while (GetDataBlock(sinfo, buf) > 0)
/* skip */;
}
LOCAL(void)
ReInitLZW (gif_source_ptr sinfo)
/* (Re)initialize LZW state; shared code for startup and Clear processing */
{
sinfo->code_size = sinfo->input_code_size + 1;
sinfo->limit_code = sinfo->clear_code << 1; /* 2^code_size */
sinfo->max_code = sinfo->clear_code + 2; /* first unused code value */
sinfo->sp = sinfo->symbol_stack; /* init stack to empty */
}
LOCAL(void)
InitLZWCode (gif_source_ptr sinfo)
/* Initialize for a series of LZWReadByte (and hence GetCode) calls */
{
/* GetCode initialization */
sinfo->last_byte = 2; /* make safe to "recopy last two bytes" */
sinfo->last_bit = 0; /* nothing in the buffer */
sinfo->cur_bit = 0; /* force buffer load on first call */
sinfo->out_of_blocks = FALSE;
/* LZWReadByte initialization: */
/* compute special code values (note that these do not change later) */
sinfo->clear_code = 1 << sinfo->input_code_size;
sinfo->end_code = sinfo->clear_code + 1;
sinfo->first_time = TRUE;
ReInitLZW(sinfo);
}
LOCAL(int)
GetCode (gif_source_ptr sinfo)
/* Fetch the next code_size bits from the GIF data */
/* We assume code_size is less than 16 */
{
register INT32 accum;
int offs, ret, count;
while ( (sinfo->cur_bit + sinfo->code_size) > sinfo->last_bit) {
/* Time to reload the buffer */
if (sinfo->out_of_blocks) {
WARNMS(sinfo->cinfo, JWRN_GIF_NOMOREDATA);
return sinfo->end_code; /* fake something useful */
}
/* preserve last two bytes of what we have -- assume code_size <= 16 */
sinfo->code_buf[0] = sinfo->code_buf[sinfo->last_byte-2];
sinfo->code_buf[1] = sinfo->code_buf[sinfo->last_byte-1];
/* Load more bytes; set flag if we reach the terminator block */
if ((count = GetDataBlock(sinfo, &sinfo->code_buf[2])) == 0) {
sinfo->out_of_blocks = TRUE;
WARNMS(sinfo->cinfo, JWRN_GIF_NOMOREDATA);
return sinfo->end_code; /* fake something useful */
}
/* Reset counters */
sinfo->cur_bit = (sinfo->cur_bit - sinfo->last_bit) + 16;
sinfo->last_byte = 2 + count;
sinfo->last_bit = sinfo->last_byte * 8;
}
/* Form up next 24 bits in accum */
offs = sinfo->cur_bit >> 3; /* byte containing cur_bit */
#ifdef CHAR_IS_UNSIGNED
accum = sinfo->code_buf[offs+2];
accum <<= 8;
accum |= sinfo->code_buf[offs+1];
accum <<= 8;
accum |= sinfo->code_buf[offs];
#else
accum = sinfo->code_buf[offs+2] & 0xFF;
accum <<= 8;
accum |= sinfo->code_buf[offs+1] & 0xFF;
accum <<= 8;
accum |= sinfo->code_buf[offs] & 0xFF;
#endif
/* Right-align cur_bit in accum, then mask off desired number of bits */
accum >>= (sinfo->cur_bit & 7);
ret = ((int) accum) & ((1 << sinfo->code_size) - 1);
sinfo->cur_bit += sinfo->code_size;
return ret;
}
LOCAL(int)
LZWReadByte (gif_source_ptr sinfo)
/* Read an LZW-compressed byte */
{
register int code; /* current working code */
int incode; /* saves actual input code */
/* First time, just eat the expected Clear code(s) and return next code, */
/* which is expected to be a raw byte. */
if (sinfo->first_time) {
sinfo->first_time = FALSE;
code = sinfo->clear_code; /* enables sharing code with Clear case */
} else {
/* If any codes are stacked from a previously read symbol, return them */
if (sinfo->sp > sinfo->symbol_stack)
return (int) *(-- sinfo->sp);
/* Time to read a new symbol */
code = GetCode(sinfo);
}
if (code == sinfo->clear_code) {
/* Reinit state, swallow any extra Clear codes, and */
/* return next code, which is expected to be a raw byte. */
ReInitLZW(sinfo);
do {
code = GetCode(sinfo);
} while (code == sinfo->clear_code);
if (code > sinfo->clear_code) { /* make sure it is a raw byte */
WARNMS(sinfo->cinfo, JWRN_GIF_BADDATA);
code = 0; /* use something valid */
}
/* make firstcode, oldcode valid! */
sinfo->firstcode = sinfo->oldcode = code;
return code;
}
if (code == sinfo->end_code) {
/* Skip the rest of the image, unless GetCode already read terminator */
if (! sinfo->out_of_blocks) {
SkipDataBlocks(sinfo);
sinfo->out_of_blocks = TRUE;
}
/* Complain that there's not enough data */
WARNMS(sinfo->cinfo, JWRN_GIF_ENDCODE);
/* Pad data with 0's */
return 0; /* fake something usable */
}
/* Got normal raw byte or LZW symbol */
incode = code; /* save for a moment */
if (code >= sinfo->max_code) { /* special case for not-yet-defined symbol */
/* code == max_code is OK; anything bigger is bad data */
if (code > sinfo->max_code) {
WARNMS(sinfo->cinfo, JWRN_GIF_BADDATA);
incode = 0; /* prevent creation of loops in symbol table */
}
/* this symbol will be defined as oldcode/firstcode */
*(sinfo->sp++) = (UINT8) sinfo->firstcode;
code = sinfo->oldcode;
}
/* If it's a symbol, expand it into the stack */
while (code >= sinfo->clear_code) {
*(sinfo->sp++) = sinfo->symbol_tail[code]; /* tail is a byte value */
code = sinfo->symbol_head[code]; /* head is another LZW symbol */
}
/* At this point code just represents a raw byte */
sinfo->firstcode = code; /* save for possible future use */
/* If there's room in table, */
if ((code = sinfo->max_code) < LZW_TABLE_SIZE) {
/* Define a new symbol = prev sym + head of this sym's expansion */
sinfo->symbol_head[code] = sinfo->oldcode;
sinfo->symbol_tail[code] = (UINT8) sinfo->firstcode;
sinfo->max_code++;
/* Is it time to increase code_size? */
if ((sinfo->max_code >= sinfo->limit_code) &&
(sinfo->code_size < MAX_LZW_BITS)) {
sinfo->code_size++;
sinfo->limit_code <<= 1; /* keep equal to 2^code_size */
}
}
sinfo->oldcode = incode; /* save last input symbol for future use */
return sinfo->firstcode; /* return first byte of symbol's expansion */
}
LOCAL(void)
ReadColorMap (gif_source_ptr sinfo, int cmaplen, JSAMPARRAY cmap)
/* Read a GIF colormap */
{
int i;
for (i = 0; i < cmaplen; i++) {
#if BITS_IN_JSAMPLE == 8
#define UPSCALE(x) (x)
#else
#define UPSCALE(x) ((x) << (BITS_IN_JSAMPLE-8))
#endif
cmap[CM_RED][i] = (JSAMPLE) UPSCALE(ReadByte(sinfo));
cmap[CM_GREEN][i] = (JSAMPLE) UPSCALE(ReadByte(sinfo));
cmap[CM_BLUE][i] = (JSAMPLE) UPSCALE(ReadByte(sinfo));
}
}
LOCAL(void)
DoExtension (gif_source_ptr sinfo)
/* Process an extension block */
/* Currently we ignore 'em all */
{
int extlabel;
/* Read extension label byte */
extlabel = ReadByte(sinfo);
TRACEMS1(sinfo->cinfo, 1, JTRC_GIF_EXTENSION, extlabel);
/* Skip the data block(s) associated with the extension */
SkipDataBlocks(sinfo);
}
/*
* Read the file header; return image size and component count.
*/
METHODDEF(void)
start_input_gif (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
gif_source_ptr source = (gif_source_ptr) sinfo;
char hdrbuf[10]; /* workspace for reading control blocks */
unsigned int width, height; /* image dimensions */
int colormaplen, aspectRatio;
int c;
/* Allocate space to store the colormap */
source->colormap = (*cinfo->mem->alloc_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE,
(JDIMENSION) MAXCOLORMAPSIZE, (JDIMENSION) NUMCOLORS);
/* Read and verify GIF Header */
if (! ReadOK(source->pub.input_file, hdrbuf, 6))
ERREXIT(cinfo, JERR_GIF_NOT);
if (hdrbuf[0] != 'G' || hdrbuf[1] != 'I' || hdrbuf[2] != 'F')
ERREXIT(cinfo, JERR_GIF_NOT);
/* Check for expected version numbers.
* If unknown version, give warning and try to process anyway;
* this is per recommendation in GIF89a standard.
*/
if ((hdrbuf[3] != '8' || hdrbuf[4] != '7' || hdrbuf[5] != 'a') &&
(hdrbuf[3] != '8' || hdrbuf[4] != '9' || hdrbuf[5] != 'a'))
TRACEMS3(cinfo, 1, JTRC_GIF_BADVERSION, hdrbuf[3], hdrbuf[4], hdrbuf[5]);
/* Read and decipher Logical Screen Descriptor */
if (! ReadOK(source->pub.input_file, hdrbuf, 7))
ERREXIT(cinfo, JERR_INPUT_EOF);
width = LM_to_uint(hdrbuf[0],hdrbuf[1]);
height = LM_to_uint(hdrbuf[2],hdrbuf[3]);
colormaplen = 2 << (hdrbuf[4] & 0x07);
/* we ignore the color resolution, sort flag, and background color index */
aspectRatio = hdrbuf[6] & 0xFF;
if (aspectRatio != 0 && aspectRatio != 49)
TRACEMS(cinfo, 1, JTRC_GIF_NONSQUARE);
/* Read global colormap if header indicates it is present */
if (BitSet(hdrbuf[4], COLORMAPFLAG))
ReadColorMap(source, colormaplen, source->colormap);
/* Scan until we reach start of desired image.
* We don't currently support skipping images, but could add it easily.
*/
for (;;) {
c = ReadByte(source);
if (c == ';') /* GIF terminator?? */
ERREXIT(cinfo, JERR_GIF_IMAGENOTFOUND);
if (c == '!') { /* Extension */
DoExtension(source);
continue;
}
if (c != ',') { /* Not an image separator? */
WARNMS1(cinfo, JWRN_GIF_CHAR, c);
continue;
}
/* Read and decipher Local Image Descriptor */
if (! ReadOK(source->pub.input_file, hdrbuf, 9))
ERREXIT(cinfo, JERR_INPUT_EOF);
/* we ignore top/left position info, also sort flag */
width = LM_to_uint(hdrbuf[4],hdrbuf[5]);
height = LM_to_uint(hdrbuf[6],hdrbuf[7]);
source->is_interlaced = BitSet(hdrbuf[8], INTERLACE);
/* Read local colormap if header indicates it is present */
/* Note: if we wanted to support skipping images, */
/* we'd need to skip rather than read colormap for ignored images */
if (BitSet(hdrbuf[8], COLORMAPFLAG)) {
colormaplen = 2 << (hdrbuf[8] & 0x07);
ReadColorMap(source, colormaplen, source->colormap);
}
source->input_code_size = ReadByte(source); /* get min-code-size byte */
if (source->input_code_size < 2 || source->input_code_size >= MAX_LZW_BITS)
ERREXIT1(cinfo, JERR_GIF_CODESIZE, source->input_code_size);
/* Reached desired image, so break out of loop */
/* If we wanted to skip this image, */
/* we'd call SkipDataBlocks and then continue the loop */
break;
}
/* Prepare to read selected image: first initialize LZW decompressor */
source->symbol_head = (UINT16 FAR *)
(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
LZW_TABLE_SIZE * SIZEOF(UINT16));
source->symbol_tail = (UINT8 FAR *)
(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
LZW_TABLE_SIZE * SIZEOF(UINT8));
source->symbol_stack = (UINT8 FAR *)
(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
LZW_TABLE_SIZE * SIZEOF(UINT8));
InitLZWCode(source);
/*
* If image is interlaced, we read it into a full-size sample array,
* decompressing as we go; then get_interlaced_row selects rows from the
* sample array in the proper order.
*/
if (source->is_interlaced) {
/* We request the virtual array now, but can't access it until virtual
* arrays have been allocated. Hence, the actual work of reading the
* image is postponed until the first call to get_pixel_rows.
*/
source->interlaced_image = (*cinfo->mem->request_virt_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
(JDIMENSION) width, (JDIMENSION) height, (JDIMENSION) 1);
if (cinfo->progress != NULL) {
cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;
progress->total_extra_passes++; /* count file input as separate pass */
}
source->pub.get_pixel_rows = load_interlaced_image;
} else {
source->pub.get_pixel_rows = get_pixel_rows;
}
/* Create compressor input buffer. */
source->pub.buffer = (*cinfo->mem->alloc_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE,
(JDIMENSION) width * NUMCOLORS, (JDIMENSION) 1);
source->pub.buffer_height = 1;
/* Return info about the image. */
cinfo->in_color_space = JCS_RGB;
cinfo->input_components = NUMCOLORS;
cinfo->data_precision = BITS_IN_JSAMPLE; /* we always rescale data to this */
cinfo->image_width = width;
cinfo->image_height = height;
TRACEMS3(cinfo, 1, JTRC_GIF, width, height, colormaplen);
}
/*
* Read one row of pixels.
* This version is used for noninterlaced GIF images:
* we read directly from the GIF file.
*/
METHODDEF(JDIMENSION)
get_pixel_rows (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
gif_source_ptr source = (gif_source_ptr) sinfo;
register int c;
register JSAMPROW ptr;
register JDIMENSION col;
register JSAMPARRAY colormap = source->colormap;
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
c = LZWReadByte(source);
*ptr++ = colormap[CM_RED][c];
*ptr++ = colormap[CM_GREEN][c];
*ptr++ = colormap[CM_BLUE][c];
}
return 1;
}
/*
* Read one row of pixels.
* This version is used for the first call on get_pixel_rows when
* reading an interlaced GIF file: we read the whole image into memory.
*/
METHODDEF(JDIMENSION)
load_interlaced_image (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
gif_source_ptr source = (gif_source_ptr) sinfo;
JSAMPARRAY image_ptr;
register JSAMPROW sptr;
register JDIMENSION col;
JDIMENSION row;
cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;
/* Read the interlaced image into the virtual array we've created. */
for (row = 0; row < cinfo->image_height; row++) {
if (progress != NULL) {
progress->pub.pass_counter = (long) row;
progress->pub.pass_limit = (long) cinfo->image_height;
(*progress->pub.progress_monitor) ((j_common_ptr) cinfo);
}
image_ptr = (*cinfo->mem->access_virt_sarray)
((j_common_ptr) cinfo, source->interlaced_image,
row, (JDIMENSION) 1, TRUE);
sptr = image_ptr[0];
for (col = cinfo->image_width; col > 0; col--) {
*sptr++ = (JSAMPLE) LZWReadByte(source);
}
}
if (progress != NULL)
progress->completed_extra_passes++;
/* Replace method pointer so subsequent calls don't come here. */
source->pub.get_pixel_rows = get_interlaced_row;
/* Initialize for get_interlaced_row, and perform first call on it. */
source->cur_row_number = 0;
source->pass2_offset = (cinfo->image_height + 7) / 8;
source->pass3_offset = source->pass2_offset + (cinfo->image_height + 3) / 8;
source->pass4_offset = source->pass3_offset + (cinfo->image_height + 1) / 4;
return get_interlaced_row(cinfo, sinfo);
}
/*
* Read one row of pixels.
* This version is used for interlaced GIF images:
* we read from the virtual array.
*/
METHODDEF(JDIMENSION)
get_interlaced_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
gif_source_ptr source = (gif_source_ptr) sinfo;
JSAMPARRAY image_ptr;
register int c;
register JSAMPROW sptr, ptr;
register JDIMENSION col;
register JSAMPARRAY colormap = source->colormap;
JDIMENSION irow;
/* Figure out which row of interlaced image is needed, and access it. */
switch ((int) (source->cur_row_number & 7)) {
case 0: /* first-pass row */
irow = source->cur_row_number >> 3;
break;
case 4: /* second-pass row */
irow = (source->cur_row_number >> 3) + source->pass2_offset;
break;
case 2: /* third-pass row */
case 6:
irow = (source->cur_row_number >> 2) + source->pass3_offset;
break;
default: /* fourth-pass row */
irow = (source->cur_row_number >> 1) + source->pass4_offset;
break;
}
image_ptr = (*cinfo->mem->access_virt_sarray)
((j_common_ptr) cinfo, source->interlaced_image,
irow, (JDIMENSION) 1, FALSE);
/* Scan the row, expand colormap, and output */
sptr = image_ptr[0];
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
c = GETJSAMPLE(*sptr++);
*ptr++ = colormap[CM_RED][c];
*ptr++ = colormap[CM_GREEN][c];
*ptr++ = colormap[CM_BLUE][c];
}
source->cur_row_number++; /* for next time */
return 1;
}
/*
* Finish up at the end of the file.
*/
METHODDEF(void)
finish_input_gif (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
/* no work */
}
/*
* The module selection routine for GIF format input.
*/
GLOBAL(cjpeg_source_ptr)
jinit_read_gif (j_compress_ptr cinfo)
{
gif_source_ptr source;
/* Create module interface object */
source = (gif_source_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(gif_source_struct));
source->cinfo = cinfo; /* make back link for subroutines */
/* Fill in method ptrs, except get_pixel_rows which start_input sets */
source->pub.start_input = start_input_gif;
source->pub.finish_input = finish_input_gif;
return (cjpeg_source_ptr) source;
}
#endif /* GIF_SUPPORTED */