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plt-scheme  4.2.1
rdppm.c
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00001 /*
00002  * rdppm.c
00003  *
00004  * Copyright (C) 1991-1997, Thomas G. Lane.
00005  * This file is part of the Independent JPEG Group's software.
00006  * For conditions of distribution and use, see the accompanying README file.
00007  *
00008  * This file contains routines to read input images in PPM/PGM format.
00009  * The extended 2-byte-per-sample raw PPM/PGM formats are supported.
00010  * The PBMPLUS library is NOT required to compile this software
00011  * (but it is highly useful as a set of PPM image manipulation programs).
00012  *
00013  * These routines may need modification for non-Unix environments or
00014  * specialized applications.  As they stand, they assume input from
00015  * an ordinary stdio stream.  They further assume that reading begins
00016  * at the start of the file; start_input may need work if the
00017  * user interface has already read some data (e.g., to determine that
00018  * the file is indeed PPM format).
00019  */
00020 
00021 #include "cdjpeg.h"         /* Common decls for cjpeg/djpeg applications */
00022 
00023 #ifdef PPM_SUPPORTED
00024 
00025 
00026 /* Portions of this code are based on the PBMPLUS library, which is:
00027 **
00028 ** Copyright (C) 1988 by Jef Poskanzer.
00029 **
00030 ** Permission to use, copy, modify, and distribute this software and its
00031 ** documentation for any purpose and without fee is hereby granted, provided
00032 ** that the above copyright notice appear in all copies and that both that
00033 ** copyright notice and this permission notice appear in supporting
00034 ** documentation.  This software is provided "as is" without express or
00035 ** implied warranty.
00036 */
00037 
00038 
00039 /* Macros to deal with unsigned chars as efficiently as compiler allows */
00040 
00041 #ifdef HAVE_UNSIGNED_CHAR
00042 typedef unsigned char U_CHAR;
00043 #define UCH(x)       ((int) (x))
00044 #else /* !HAVE_UNSIGNED_CHAR */
00045 #ifdef CHAR_IS_UNSIGNED
00046 typedef char U_CHAR;
00047 #define UCH(x)       ((int) (x))
00048 #else
00049 typedef char U_CHAR;
00050 #define UCH(x)       ((int) (x) & 0xFF)
00051 #endif
00052 #endif /* HAVE_UNSIGNED_CHAR */
00053 
00054 
00055 #define       ReadOK(file,buffer,len)     (JFREAD(file,buffer,len) == ((size_t) (len)))
00056 
00057 
00058 /*
00059  * On most systems, reading individual bytes with getc() is drastically less
00060  * efficient than buffering a row at a time with fread().  On PCs, we must
00061  * allocate the buffer in near data space, because we are assuming small-data
00062  * memory model, wherein fread() can't reach far memory.  If you need to
00063  * process very wide images on a PC, you might have to compile in large-memory
00064  * model, or else replace fread() with a getc() loop --- which will be much
00065  * slower.
00066  */
00067 
00068 
00069 /* Private version of data source object */
00070 
00071 typedef struct {
00072   struct cjpeg_source_struct pub; /* public fields */
00073 
00074   U_CHAR *iobuffer;         /* non-FAR pointer to I/O buffer */
00075   JSAMPROW pixrow;          /* FAR pointer to same */
00076   size_t buffer_width;             /* width of I/O buffer */
00077   JSAMPLE *rescale;         /* => maxval-remapping array, or NULL */
00078 } ppm_source_struct;
00079 
00080 typedef ppm_source_struct * ppm_source_ptr;
00081 
00082 
00083 LOCAL(int)
00084 pbm_getc (FILE * infile)
00085 /* Read next char, skipping over any comments */
00086 /* A comment/newline sequence is returned as a newline */
00087 {
00088   register int ch;
00089 
00090   ch = getc(infile);
00091   if (ch == '#') {
00092     do {
00093       ch = getc(infile);
00094     } while (ch != '\n' && ch != EOF);
00095   }
00096   return ch;
00097 }
00098 
00099 
00100 LOCAL(unsigned int)
00101 read_pbm_integer (j_compress_ptr cinfo, FILE * infile)
00102 /* Read an unsigned decimal integer from the PPM file */
00103 /* Swallows one trailing character after the integer */
00104 /* Note that on a 16-bit-int machine, only values up to 64k can be read. */
00105 /* This should not be a problem in practice. */
00106 {
00107   register int ch;
00108   register unsigned int val;
00109 
00110   /* Skip any leading whitespace */
00111   do {
00112     ch = pbm_getc(infile);
00113     if (ch == EOF)
00114       ERREXIT(cinfo, JERR_INPUT_EOF);
00115   } while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
00116 
00117   if (ch < '0' || ch > '9')
00118     ERREXIT(cinfo, JERR_PPM_NONNUMERIC);
00119 
00120   val = ch - '0';
00121   while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {
00122     val *= 10;
00123     val += ch - '0';
00124   }
00125   return val;
00126 }
00127 
00128 
00129 /*
00130  * Read one row of pixels.
00131  *
00132  * We provide several different versions depending on input file format.
00133  * In all cases, input is scaled to the size of JSAMPLE.
00134  *
00135  * A really fast path is provided for reading byte/sample raw files with
00136  * maxval = MAXJSAMPLE, which is the normal case for 8-bit data.
00137  */
00138 
00139 
00140 METHODDEF(JDIMENSION)
00141 get_text_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00142 /* This version is for reading text-format PGM files with any maxval */
00143 {
00144   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00145   FILE * infile = source->pub.input_file;
00146   register JSAMPROW ptr;
00147   register JSAMPLE *rescale = source->rescale;
00148   JDIMENSION col;
00149 
00150   ptr = source->pub.buffer[0];
00151   for (col = cinfo->image_width; col > 0; col--) {
00152     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
00153   }
00154   return 1;
00155 }
00156 
00157 
00158 METHODDEF(JDIMENSION)
00159 get_text_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00160 /* This version is for reading text-format PPM files with any maxval */
00161 {
00162   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00163   FILE * infile = source->pub.input_file;
00164   register JSAMPROW ptr;
00165   register JSAMPLE *rescale = source->rescale;
00166   JDIMENSION col;
00167 
00168   ptr = source->pub.buffer[0];
00169   for (col = cinfo->image_width; col > 0; col--) {
00170     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
00171     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
00172     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
00173   }
00174   return 1;
00175 }
00176 
00177 
00178 METHODDEF(JDIMENSION)
00179 get_scaled_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00180 /* This version is for reading raw-byte-format PGM files with any maxval */
00181 {
00182   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00183   register JSAMPROW ptr;
00184   register U_CHAR * bufferptr;
00185   register JSAMPLE *rescale = source->rescale;
00186   JDIMENSION col;
00187 
00188   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
00189     ERREXIT(cinfo, JERR_INPUT_EOF);
00190   ptr = source->pub.buffer[0];
00191   bufferptr = source->iobuffer;
00192   for (col = cinfo->image_width; col > 0; col--) {
00193     *ptr++ = rescale[UCH(*bufferptr++)];
00194   }
00195   return 1;
00196 }
00197 
00198 
00199 METHODDEF(JDIMENSION)
00200 get_scaled_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00201 /* This version is for reading raw-byte-format PPM files with any maxval */
00202 {
00203   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00204   register JSAMPROW ptr;
00205   register U_CHAR * bufferptr;
00206   register JSAMPLE *rescale = source->rescale;
00207   JDIMENSION col;
00208 
00209   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
00210     ERREXIT(cinfo, JERR_INPUT_EOF);
00211   ptr = source->pub.buffer[0];
00212   bufferptr = source->iobuffer;
00213   for (col = cinfo->image_width; col > 0; col--) {
00214     *ptr++ = rescale[UCH(*bufferptr++)];
00215     *ptr++ = rescale[UCH(*bufferptr++)];
00216     *ptr++ = rescale[UCH(*bufferptr++)];
00217   }
00218   return 1;
00219 }
00220 
00221 
00222 METHODDEF(JDIMENSION)
00223 get_raw_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00224 /* This version is for reading raw-byte-format files with maxval = MAXJSAMPLE.
00225  * In this case we just read right into the JSAMPLE buffer!
00226  * Note that same code works for PPM and PGM files.
00227  */
00228 {
00229   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00230 
00231   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
00232     ERREXIT(cinfo, JERR_INPUT_EOF);
00233   return 1;
00234 }
00235 
00236 
00237 METHODDEF(JDIMENSION)
00238 get_word_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00239 /* This version is for reading raw-word-format PGM files with any maxval */
00240 {
00241   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00242   register JSAMPROW ptr;
00243   register U_CHAR * bufferptr;
00244   register JSAMPLE *rescale = source->rescale;
00245   JDIMENSION col;
00246 
00247   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
00248     ERREXIT(cinfo, JERR_INPUT_EOF);
00249   ptr = source->pub.buffer[0];
00250   bufferptr = source->iobuffer;
00251   for (col = cinfo->image_width; col > 0; col--) {
00252     register int temp;
00253     temp  = UCH(*bufferptr++);
00254     temp |= UCH(*bufferptr++) << 8;
00255     *ptr++ = rescale[temp];
00256   }
00257   return 1;
00258 }
00259 
00260 
00261 METHODDEF(JDIMENSION)
00262 get_word_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00263 /* This version is for reading raw-word-format PPM files with any maxval */
00264 {
00265   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00266   register JSAMPROW ptr;
00267   register U_CHAR * bufferptr;
00268   register JSAMPLE *rescale = source->rescale;
00269   JDIMENSION col;
00270 
00271   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
00272     ERREXIT(cinfo, JERR_INPUT_EOF);
00273   ptr = source->pub.buffer[0];
00274   bufferptr = source->iobuffer;
00275   for (col = cinfo->image_width; col > 0; col--) {
00276     register int temp;
00277     temp  = UCH(*bufferptr++);
00278     temp |= UCH(*bufferptr++) << 8;
00279     *ptr++ = rescale[temp];
00280     temp  = UCH(*bufferptr++);
00281     temp |= UCH(*bufferptr++) << 8;
00282     *ptr++ = rescale[temp];
00283     temp  = UCH(*bufferptr++);
00284     temp |= UCH(*bufferptr++) << 8;
00285     *ptr++ = rescale[temp];
00286   }
00287   return 1;
00288 }
00289 
00290 
00291 /*
00292  * Read the file header; return image size and component count.
00293  */
00294 
00295 METHODDEF(void)
00296 start_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00297 {
00298   ppm_source_ptr source = (ppm_source_ptr) sinfo;
00299   int c;
00300   unsigned int w, h, maxval;
00301   boolean need_iobuffer, use_raw_buffer, need_rescale;
00302 
00303   if (getc(source->pub.input_file) != 'P')
00304     ERREXIT(cinfo, JERR_PPM_NOT);
00305 
00306   c = getc(source->pub.input_file); /* subformat discriminator character */
00307 
00308   /* detect unsupported variants (ie, PBM) before trying to read header */
00309   switch (c) {
00310   case '2':                 /* it's a text-format PGM file */
00311   case '3':                 /* it's a text-format PPM file */
00312   case '5':                 /* it's a raw-format PGM file */
00313   case '6':                 /* it's a raw-format PPM file */
00314     break;
00315   default:
00316     ERREXIT(cinfo, JERR_PPM_NOT);
00317     break;
00318   }
00319 
00320   /* fetch the remaining header info */
00321   w = read_pbm_integer(cinfo, source->pub.input_file);
00322   h = read_pbm_integer(cinfo, source->pub.input_file);
00323   maxval = read_pbm_integer(cinfo, source->pub.input_file);
00324 
00325   if (w <= 0 || h <= 0 || maxval <= 0) /* error check */
00326     ERREXIT(cinfo, JERR_PPM_NOT);
00327 
00328   cinfo->data_precision = BITS_IN_JSAMPLE; /* we always rescale data to this */
00329   cinfo->image_width = (JDIMENSION) w;
00330   cinfo->image_height = (JDIMENSION) h;
00331 
00332   /* initialize flags to most common settings */
00333   need_iobuffer = TRUE;            /* do we need an I/O buffer? */
00334   use_raw_buffer = FALSE;   /* do we map input buffer onto I/O buffer? */
00335   need_rescale = TRUE;             /* do we need a rescale array? */
00336 
00337   switch (c) {
00338   case '2':                 /* it's a text-format PGM file */
00339     cinfo->input_components = 1;
00340     cinfo->in_color_space = JCS_GRAYSCALE;
00341     TRACEMS2(cinfo, 1, JTRC_PGM_TEXT, w, h);
00342     source->pub.get_pixel_rows = get_text_gray_row;
00343     need_iobuffer = FALSE;
00344     break;
00345 
00346   case '3':                 /* it's a text-format PPM file */
00347     cinfo->input_components = 3;
00348     cinfo->in_color_space = JCS_RGB;
00349     TRACEMS2(cinfo, 1, JTRC_PPM_TEXT, w, h);
00350     source->pub.get_pixel_rows = get_text_rgb_row;
00351     need_iobuffer = FALSE;
00352     break;
00353 
00354   case '5':                 /* it's a raw-format PGM file */
00355     cinfo->input_components = 1;
00356     cinfo->in_color_space = JCS_GRAYSCALE;
00357     TRACEMS2(cinfo, 1, JTRC_PGM, w, h);
00358     if (maxval > 255) {
00359       source->pub.get_pixel_rows = get_word_gray_row;
00360     } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
00361       source->pub.get_pixel_rows = get_raw_row;
00362       use_raw_buffer = TRUE;
00363       need_rescale = FALSE;
00364     } else {
00365       source->pub.get_pixel_rows = get_scaled_gray_row;
00366     }
00367     break;
00368 
00369   case '6':                 /* it's a raw-format PPM file */
00370     cinfo->input_components = 3;
00371     cinfo->in_color_space = JCS_RGB;
00372     TRACEMS2(cinfo, 1, JTRC_PPM, w, h);
00373     if (maxval > 255) {
00374       source->pub.get_pixel_rows = get_word_rgb_row;
00375     } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
00376       source->pub.get_pixel_rows = get_raw_row;
00377       use_raw_buffer = TRUE;
00378       need_rescale = FALSE;
00379     } else {
00380       source->pub.get_pixel_rows = get_scaled_rgb_row;
00381     }
00382     break;
00383   }
00384 
00385   /* Allocate space for I/O buffer: 1 or 3 bytes or words/pixel. */
00386   if (need_iobuffer) {
00387     source->buffer_width = (size_t) w * cinfo->input_components *
00388       ((maxval<=255) ? SIZEOF(U_CHAR) : (2*SIZEOF(U_CHAR)));
00389     source->iobuffer = (U_CHAR *)
00390       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00391                               source->buffer_width);
00392   }
00393 
00394   /* Create compressor input buffer. */
00395   if (use_raw_buffer) {
00396     /* For unscaled raw-input case, we can just map it onto the I/O buffer. */
00397     /* Synthesize a JSAMPARRAY pointer structure */
00398     /* Cast here implies near->far pointer conversion on PCs */
00399     source->pixrow = (JSAMPROW) source->iobuffer;
00400     source->pub.buffer = & source->pixrow;
00401     source->pub.buffer_height = 1;
00402   } else {
00403     /* Need to translate anyway, so make a separate sample buffer. */
00404     source->pub.buffer = (*cinfo->mem->alloc_sarray)
00405       ((j_common_ptr) cinfo, JPOOL_IMAGE,
00406        (JDIMENSION) w * cinfo->input_components, (JDIMENSION) 1);
00407     source->pub.buffer_height = 1;
00408   }
00409 
00410   /* Compute the rescaling array if required. */
00411   if (need_rescale) {
00412     INT32 val, half_maxval;
00413 
00414     /* On 16-bit-int machines we have to be careful of maxval = 65535 */
00415     source->rescale = (JSAMPLE *)
00416       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00417                               (size_t) (((long) maxval + 1L) * SIZEOF(JSAMPLE)));
00418     half_maxval = maxval / 2;
00419     for (val = 0; val <= (INT32) maxval; val++) {
00420       /* The multiplication here must be done in 32 bits to avoid overflow */
00421       source->rescale[val] = (JSAMPLE) ((val*MAXJSAMPLE + half_maxval)/maxval);
00422     }
00423   }
00424 }
00425 
00426 
00427 /*
00428  * Finish up at the end of the file.
00429  */
00430 
00431 METHODDEF(void)
00432 finish_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
00433 {
00434   /* no work */
00435 }
00436 
00437 
00438 /*
00439  * The module selection routine for PPM format input.
00440  */
00441 
00442 GLOBAL(cjpeg_source_ptr)
00443 jinit_read_ppm (j_compress_ptr cinfo)
00444 {
00445   ppm_source_ptr source;
00446 
00447   /* Create module interface object */
00448   source = (ppm_source_ptr)
00449       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00450                               SIZEOF(ppm_source_struct));
00451   /* Fill in method ptrs, except get_pixel_rows which start_input sets */
00452   source->pub.start_input = start_input_ppm;
00453   source->pub.finish_input = finish_input_ppm;
00454 
00455   return (cjpeg_source_ptr) source;
00456 }
00457 
00458 #endif /* PPM_SUPPORTED */