ref: 931ae0cfebeb46892406efc7468636e59f8110a9
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 */