| /* |
| * rdppm.c |
| * |
| * Copyright (C) 1991-1994, 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 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 */ |
| JDIMENSION buffer_width; /* width of one row */ |
| 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. |
| * |
| * Note that a really fast path is provided for reading raw files with |
| * maxval = MAXJSAMPLE, which is the normal case (at least for 8-bit JSAMPLEs). |
| */ |
| |
| |
| 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-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-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-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; |
| } |
| |
| |
| /* |
| * 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 can_use_raw; |
| |
| if (getc(source->pub.input_file) != 'P') |
| ERREXIT(cinfo, JERR_PPM_NOT); |
| |
| c = getc(source->pub.input_file); /* save format discriminator for a sec */ |
| |
| /* while we 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; |
| |
| /* Raw PPM/PGM matches JSAMPLE representation iff: */ |
| can_use_raw = (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)); |
| |
| 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; |
| can_use_raw = FALSE; /* force a rescale array to be made */ |
| 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; |
| can_use_raw = FALSE; /* force a rescale array to be made */ |
| 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 (can_use_raw) |
| source->pub.get_pixel_rows = get_raw_row; |
| else |
| source->pub.get_pixel_rows = get_scaled_gray_row; |
| /* allocate space for I/O buffer: 1 byte/pixel */ |
| source->iobuffer = (U_CHAR *) |
| (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| (size_t) (SIZEOF(U_CHAR) * (size_t) w)); |
| 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 (can_use_raw) |
| source->pub.get_pixel_rows = get_raw_row; |
| else |
| source->pub.get_pixel_rows = get_scaled_rgb_row; |
| /* allocate space for I/O buffer: 3 bytes/pixel */ |
| source->iobuffer = (U_CHAR *) |
| (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| (size_t) (3 * SIZEOF(U_CHAR) * (size_t) w)); |
| break; |
| |
| default: |
| ERREXIT(cinfo, JERR_PPM_NOT); |
| break; |
| } |
| |
| /* Create compressor input buffer. */ |
| source->buffer_width = (JDIMENSION) w * cinfo->input_components; |
| if (can_use_raw) { |
| /* 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, |
| source->buffer_width, (JDIMENSION) 1); |
| source->pub.buffer_height = 1; |
| } |
| |
| /* Compute the rescaling array if required (we use it for all but raw) */ |
| if (can_use_raw) { |
| source->rescale = NULL; /* no rescaling required */ |
| } else { |
| 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 */ |