ref: dfb4b522830edab8f3856289d326d6cf5e930644
dir: /sys/src/cmd/gs/jpeg/rdppm.c/
/*
* rdppm.c
*
* Copyright (C) 1991-1997, 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.
*
* This file contains routines to read input images in PPM/PGM format.
* The extended 2-byte-per-sample raw PPM/PGM formats are supported.
* The PBMPLUS library is NOT required to compile this software
* (but it is highly useful as a set of PPM image manipulation programs).
*
* 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; start_input may need work if the
* user interface has already read some data (e.g., to determine that
* the file is indeed PPM format).
*/
#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
#ifdef PPM_SUPPORTED
/* Portions of this code are based on the PBMPLUS library, which is:
**
** Copyright (C) 1988 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.
*/
/* Macros to deal with unsigned chars as efficiently as compiler allows */
#ifdef HAVE_UNSIGNED_CHAR
typedef unsigned char U_CHAR;
#define UCH(x) ((int) (x))
#else /* !HAVE_UNSIGNED_CHAR */
#ifdef CHAR_IS_UNSIGNED
typedef char U_CHAR;
#define UCH(x) ((int) (x))
#else
typedef char U_CHAR;
#define UCH(x) ((int) (x) & 0xFF)
#endif
#endif /* HAVE_UNSIGNED_CHAR */
#define ReadOK(file,buffer,len) (JFREAD(file,buffer,len) == ((size_t) (len)))
/*
* On most systems, reading individual bytes with getc() is drastically less
* efficient than buffering a row at a time with fread(). On PCs, we must
* allocate the buffer in near data space, because we are assuming small-data
* memory model, wherein fread() can't reach far memory. If you need to
* process very wide images on a PC, you might have to compile in large-memory
* model, or else replace fread() with a getc() loop --- which will be much
* slower.
*/
/* Private version of data source object */
typedef struct {
struct cjpeg_source_struct pub; /* public fields */
U_CHAR *iobuffer; /* non-FAR pointer to I/O buffer */
JSAMPROW pixrow; /* FAR pointer to same */
size_t buffer_width; /* width of I/O buffer */
JSAMPLE *rescale; /* => maxval-remapping array, or NULL */
} ppm_source_struct;
typedef ppm_source_struct * ppm_source_ptr;
LOCAL(int)
pbm_getc (FILE * infile)
/* Read next char, skipping over any comments */
/* A comment/newline sequence is returned as a newline */
{
register int ch;
ch = getc(infile);
if (ch == '#') {
do {
ch = getc(infile);
} while (ch != '\n' && ch != EOF);
}
return ch;
}
LOCAL(unsigned int)
read_pbm_integer (j_compress_ptr cinfo, FILE * infile)
/* Read an unsigned decimal integer from the PPM file */
/* Swallows one trailing character after the integer */
/* Note that on a 16-bit-int machine, only values up to 64k can be read. */
/* This should not be a problem in practice. */
{
register int ch;
register unsigned int val;
/* Skip any leading whitespace */
do {
ch = pbm_getc(infile);
if (ch == EOF)
ERREXIT(cinfo, JERR_INPUT_EOF);
} while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
if (ch < '0' || ch > '9')
ERREXIT(cinfo, JERR_PPM_NONNUMERIC);
val = ch - '0';
while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {
val *= 10;
val += ch - '0';
}
return val;
}
/*
* Read one row of pixels.
*
* We provide several different versions depending on input file format.
* In all cases, input is scaled to the size of JSAMPLE.
*
* A really fast path is provided for reading byte/sample raw files with
* maxval = MAXJSAMPLE, which is the normal case for 8-bit data.
*/
METHODDEF(JDIMENSION)
get_text_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading text-format PGM files with any maxval */
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
FILE * infile = source->pub.input_file;
register JSAMPROW ptr;
register JSAMPLE *rescale = source->rescale;
JDIMENSION col;
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
*ptr++ = rescale[read_pbm_integer(cinfo, infile)];
}
return 1;
}
METHODDEF(JDIMENSION)
get_text_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading text-format PPM files with any maxval */
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
FILE * infile = source->pub.input_file;
register JSAMPROW ptr;
register JSAMPLE *rescale = source->rescale;
JDIMENSION col;
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
*ptr++ = rescale[read_pbm_integer(cinfo, infile)];
*ptr++ = rescale[read_pbm_integer(cinfo, infile)];
*ptr++ = rescale[read_pbm_integer(cinfo, infile)];
}
return 1;
}
METHODDEF(JDIMENSION)
get_scaled_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading raw-byte-format PGM files with any maxval */
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
register JSAMPROW ptr;
register U_CHAR * bufferptr;
register JSAMPLE *rescale = source->rescale;
JDIMENSION col;
if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
ERREXIT(cinfo, JERR_INPUT_EOF);
ptr = source->pub.buffer[0];
bufferptr = source->iobuffer;
for (col = cinfo->image_width; col > 0; col--) {
*ptr++ = rescale[UCH(*bufferptr++)];
}
return 1;
}
METHODDEF(JDIMENSION)
get_scaled_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading raw-byte-format PPM files with any maxval */
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
register JSAMPROW ptr;
register U_CHAR * bufferptr;
register JSAMPLE *rescale = source->rescale;
JDIMENSION col;
if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
ERREXIT(cinfo, JERR_INPUT_EOF);
ptr = source->pub.buffer[0];
bufferptr = source->iobuffer;
for (col = cinfo->image_width; col > 0; col--) {
*ptr++ = rescale[UCH(*bufferptr++)];
*ptr++ = rescale[UCH(*bufferptr++)];
*ptr++ = rescale[UCH(*bufferptr++)];
}
return 1;
}
METHODDEF(JDIMENSION)
get_raw_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading raw-byte-format files with maxval = MAXJSAMPLE.
* In this case we just read right into the JSAMPLE buffer!
* Note that same code works for PPM and PGM files.
*/
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
ERREXIT(cinfo, JERR_INPUT_EOF);
return 1;
}
METHODDEF(JDIMENSION)
get_word_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading raw-word-format PGM files with any maxval */
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
register JSAMPROW ptr;
register U_CHAR * bufferptr;
register JSAMPLE *rescale = source->rescale;
JDIMENSION col;
if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
ERREXIT(cinfo, JERR_INPUT_EOF);
ptr = source->pub.buffer[0];
bufferptr = source->iobuffer;
for (col = cinfo->image_width; col > 0; col--) {
register int temp;
temp = UCH(*bufferptr++);
temp |= UCH(*bufferptr++) << 8;
*ptr++ = rescale[temp];
}
return 1;
}
METHODDEF(JDIMENSION)
get_word_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading raw-word-format PPM files with any maxval */
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
register JSAMPROW ptr;
register U_CHAR * bufferptr;
register JSAMPLE *rescale = source->rescale;
JDIMENSION col;
if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
ERREXIT(cinfo, JERR_INPUT_EOF);
ptr = source->pub.buffer[0];
bufferptr = source->iobuffer;
for (col = cinfo->image_width; col > 0; col--) {
register int temp;
temp = UCH(*bufferptr++);
temp |= UCH(*bufferptr++) << 8;
*ptr++ = rescale[temp];
temp = UCH(*bufferptr++);
temp |= UCH(*bufferptr++) << 8;
*ptr++ = rescale[temp];
temp = UCH(*bufferptr++);
temp |= UCH(*bufferptr++) << 8;
*ptr++ = rescale[temp];
}
return 1;
}
/*
* Read the file header; return image size and component count.
*/
METHODDEF(void)
start_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
ppm_source_ptr source = (ppm_source_ptr) sinfo;
int c;
unsigned int w, h, maxval;
boolean need_iobuffer, use_raw_buffer, need_rescale;
if (getc(source->pub.input_file) != 'P')
ERREXIT(cinfo, JERR_PPM_NOT);
c = getc(source->pub.input_file); /* subformat discriminator character */
/* detect unsupported variants (ie, PBM) before trying to read header */
switch (c) {
case '2': /* it's a text-format PGM file */
case '3': /* it's a text-format PPM file */
case '5': /* it's a raw-format PGM file */
case '6': /* it's a raw-format PPM file */
break;
default:
ERREXIT(cinfo, JERR_PPM_NOT);
break;
}
/* fetch the remaining header info */
w = read_pbm_integer(cinfo, source->pub.input_file);
h = read_pbm_integer(cinfo, source->pub.input_file);
maxval = read_pbm_integer(cinfo, source->pub.input_file);
if (w <= 0 || h <= 0 || maxval <= 0) /* error check */
ERREXIT(cinfo, JERR_PPM_NOT);
cinfo->data_precision = BITS_IN_JSAMPLE; /* we always rescale data to this */
cinfo->image_width = (JDIMENSION) w;
cinfo->image_height = (JDIMENSION) h;
/* initialize flags to most common settings */
need_iobuffer = TRUE; /* do we need an I/O buffer? */
use_raw_buffer = FALSE; /* do we map input buffer onto I/O buffer? */
need_rescale = TRUE; /* do we need a rescale array? */
switch (c) {
case '2': /* it's a text-format PGM file */
cinfo->input_components = 1;
cinfo->in_color_space = JCS_GRAYSCALE;
TRACEMS2(cinfo, 1, JTRC_PGM_TEXT, w, h);
source->pub.get_pixel_rows = get_text_gray_row;
need_iobuffer = FALSE;
break;
case '3': /* it's a text-format PPM file */
cinfo->input_components = 3;
cinfo->in_color_space = JCS_RGB;
TRACEMS2(cinfo, 1, JTRC_PPM_TEXT, w, h);
source->pub.get_pixel_rows = get_text_rgb_row;
need_iobuffer = FALSE;
break;
case '5': /* it's a raw-format PGM file */
cinfo->input_components = 1;
cinfo->in_color_space = JCS_GRAYSCALE;
TRACEMS2(cinfo, 1, JTRC_PGM, w, h);
if (maxval > 255) {
source->pub.get_pixel_rows = get_word_gray_row;
} else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
source->pub.get_pixel_rows = get_raw_row;
use_raw_buffer = TRUE;
need_rescale = FALSE;
} else {
source->pub.get_pixel_rows = get_scaled_gray_row;
}
break;
case '6': /* it's a raw-format PPM file */
cinfo->input_components = 3;
cinfo->in_color_space = JCS_RGB;
TRACEMS2(cinfo, 1, JTRC_PPM, w, h);
if (maxval > 255) {
source->pub.get_pixel_rows = get_word_rgb_row;
} else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
source->pub.get_pixel_rows = get_raw_row;
use_raw_buffer = TRUE;
need_rescale = FALSE;
} else {
source->pub.get_pixel_rows = get_scaled_rgb_row;
}
break;
}
/* Allocate space for I/O buffer: 1 or 3 bytes or words/pixel. */
if (need_iobuffer) {
source->buffer_width = (size_t) w * cinfo->input_components *
((maxval<=255) ? SIZEOF(U_CHAR) : (2*SIZEOF(U_CHAR)));
source->iobuffer = (U_CHAR *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
source->buffer_width);
}
/* Create compressor input buffer. */
if (use_raw_buffer) {
/* For unscaled raw-input case, we can just map it onto the I/O buffer. */
/* Synthesize a JSAMPARRAY pointer structure */
/* Cast here implies near->far pointer conversion on PCs */
source->pixrow = (JSAMPROW) source->iobuffer;
source->pub.buffer = & source->pixrow;
source->pub.buffer_height = 1;
} else {
/* Need to translate anyway, so make a separate sample buffer. */
source->pub.buffer = (*cinfo->mem->alloc_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE,
(JDIMENSION) w * cinfo->input_components, (JDIMENSION) 1);
source->pub.buffer_height = 1;
}
/* Compute the rescaling array if required. */
if (need_rescale) {
INT32 val, half_maxval;
/* On 16-bit-int machines we have to be careful of maxval = 65535 */
source->rescale = (JSAMPLE *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
(size_t) (((long) maxval + 1L) * SIZEOF(JSAMPLE)));
half_maxval = maxval / 2;
for (val = 0; val <= (INT32) maxval; val++) {
/* The multiplication here must be done in 32 bits to avoid overflow */
source->rescale[val] = (JSAMPLE) ((val*MAXJSAMPLE + half_maxval)/maxval);
}
}
}
/*
* Finish up at the end of the file.
*/
METHODDEF(void)
finish_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
/* no work */
}
/*
* The module selection routine for PPM format input.
*/
GLOBAL(cjpeg_source_ptr)
jinit_read_ppm (j_compress_ptr cinfo)
{
ppm_source_ptr source;
/* Create module interface object */
source = (ppm_source_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(ppm_source_struct));
/* Fill in method ptrs, except get_pixel_rows which start_input sets */
source->pub.start_input = start_input_ppm;
source->pub.finish_input = finish_input_ppm;
return (cjpeg_source_ptr) source;
}
#endif /* PPM_SUPPORTED */