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      1 /*
      2  * rdppm.c
      3  *
      4  * Copyright (C) 1991-1997, Thomas G. Lane.
      5  * This file is part of the Independent JPEG Group's software.
      6  * For conditions of distribution and use, see the accompanying README file.
      7  *
      8  * This file contains routines to read input images in PPM/PGM format.
      9  * The extended 2-byte-per-sample raw PPM/PGM formats are supported.
     10  * The PBMPLUS library is NOT required to compile this software
     11  * (but it is highly useful as a set of PPM image manipulation programs).
     12  *
     13  * These routines may need modification for non-Unix environments or
     14  * specialized applications.  As they stand, they assume input from
     15  * an ordinary stdio stream.  They further assume that reading begins
     16  * at the start of the file; start_input may need work if the
     17  * user interface has already read some data (e.g., to determine that
     18  * the file is indeed PPM format).
     19  */
     20 
     21 #include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */
     22 
     23 #ifdef PPM_SUPPORTED
     24 
     25 
     26 /* Portions of this code are based on the PBMPLUS library, which is:
     27 **
     28 ** Copyright (C) 1988 by Jef Poskanzer.
     29 **
     30 ** Permission to use, copy, modify, and distribute this software and its
     31 ** documentation for any purpose and without fee is hereby granted, provided
     32 ** that the above copyright notice appear in all copies and that both that
     33 ** copyright notice and this permission notice appear in supporting
     34 ** documentation.  This software is provided "as is" without express or
     35 ** implied warranty.
     36 */
     37 
     38 
     39 /* Macros to deal with unsigned chars as efficiently as compiler allows */
     40 
     41 #ifdef HAVE_UNSIGNED_CHAR
     42 typedef unsigned char U_CHAR;
     43 #define UCH(x)	((int) (x))
     44 #else /* !HAVE_UNSIGNED_CHAR */
     45 #ifdef CHAR_IS_UNSIGNED
     46 typedef char U_CHAR;
     47 #define UCH(x)	((int) (x))
     48 #else
     49 typedef char U_CHAR;
     50 #define UCH(x)	((int) (x) & 0xFF)
     51 #endif
     52 #endif /* HAVE_UNSIGNED_CHAR */
     53 
     54 
     55 #define	ReadOK(file,buffer,len)	(JFREAD(file,buffer,len) == ((size_t) (len)))
     56 
     57 
     58 /*
     59  * On most systems, reading individual bytes with getc() is drastically less
     60  * efficient than buffering a row at a time with fread().  On PCs, we must
     61  * allocate the buffer in near data space, because we are assuming small-data
     62  * memory model, wherein fread() can't reach far memory.  If you need to
     63  * process very wide images on a PC, you might have to compile in large-memory
     64  * model, or else replace fread() with a getc() loop --- which will be much
     65  * slower.
     66  */
     67 
     68 
     69 /* Private version of data source object */
     70 
     71 typedef struct {
     72   struct cjpeg_source_struct pub; /* public fields */
     73 
     74   U_CHAR *iobuffer;		/* non-FAR pointer to I/O buffer */
     75   JSAMPROW pixrow;		/* FAR pointer to same */
     76   size_t buffer_width;		/* width of I/O buffer */
     77   JSAMPLE *rescale;		/* => maxval-remapping array, or NULL */
     78 } ppm_source_struct;
     79 
     80 typedef ppm_source_struct * ppm_source_ptr;
     81 
     82 
     83 LOCAL(int)
     84 pbm_getc (FILE * infile)
     85 /* Read next char, skipping over any comments */
     86 /* A comment/newline sequence is returned as a newline */
     87 {
     88   register int ch;
     89 
     90   ch = getc(infile);
     91   if (ch == '#') {
     92     do {
     93       ch = getc(infile);
     94     } while (ch != '\n' && ch != EOF);
     95   }
     96   return ch;
     97 }
     98 
     99 
    100 LOCAL(unsigned int)
    101 read_pbm_integer (j_compress_ptr cinfo, FILE * infile)
    102 /* Read an unsigned decimal integer from the PPM file */
    103 /* Swallows one trailing character after the integer */
    104 /* Note that on a 16-bit-int machine, only values up to 64k can be read. */
    105 /* This should not be a problem in practice. */
    106 {
    107   register int ch;
    108   register unsigned int val;
    109 
    110   /* Skip any leading whitespace */
    111   do {
    112     ch = pbm_getc(infile);
    113     if (ch == EOF)
    114       ERREXIT(cinfo, JERR_INPUT_EOF);
    115   } while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
    116 
    117   if (ch < '0' || ch > '9')
    118     ERREXIT(cinfo, JERR_PPM_NONNUMERIC);
    119 
    120   val = ch - '0';
    121   while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {
    122     val *= 10;
    123     val += ch - '0';
    124   }
    125   return val;
    126 }
    127 
    128 
    129 /*
    130  * Read one row of pixels.
    131  *
    132  * We provide several different versions depending on input file format.
    133  * In all cases, input is scaled to the size of JSAMPLE.
    134  *
    135  * A really fast path is provided for reading byte/sample raw files with
    136  * maxval = MAXJSAMPLE, which is the normal case for 8-bit data.
    137  */
    138 
    139 
    140 METHODDEF(JDIMENSION)
    141 get_text_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    142 /* This version is for reading text-format PGM files with any maxval */
    143 {
    144   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    145   FILE * infile = source->pub.input_file;
    146   register JSAMPROW ptr;
    147   register JSAMPLE *rescale = source->rescale;
    148   JDIMENSION col;
    149 
    150   ptr = source->pub.buffer[0];
    151   for (col = cinfo->image_width; col > 0; col--) {
    152     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
    153   }
    154   return 1;
    155 }
    156 
    157 
    158 METHODDEF(JDIMENSION)
    159 get_text_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    160 /* This version is for reading text-format PPM files with any maxval */
    161 {
    162   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    163   FILE * infile = source->pub.input_file;
    164   register JSAMPROW ptr;
    165   register JSAMPLE *rescale = source->rescale;
    166   JDIMENSION col;
    167 
    168   ptr = source->pub.buffer[0];
    169   for (col = cinfo->image_width; col > 0; col--) {
    170     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
    171     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
    172     *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
    173   }
    174   return 1;
    175 }
    176 
    177 
    178 METHODDEF(JDIMENSION)
    179 get_scaled_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    180 /* This version is for reading raw-byte-format PGM files with any maxval */
    181 {
    182   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    183   register JSAMPROW ptr;
    184   register U_CHAR * bufferptr;
    185   register JSAMPLE *rescale = source->rescale;
    186   JDIMENSION col;
    187 
    188   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
    189     ERREXIT(cinfo, JERR_INPUT_EOF);
    190   ptr = source->pub.buffer[0];
    191   bufferptr = source->iobuffer;
    192   for (col = cinfo->image_width; col > 0; col--) {
    193     *ptr++ = rescale[UCH(*bufferptr++)];
    194   }
    195   return 1;
    196 }
    197 
    198 
    199 METHODDEF(JDIMENSION)
    200 get_scaled_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    201 /* This version is for reading raw-byte-format PPM files with any maxval */
    202 {
    203   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    204   register JSAMPROW ptr;
    205   register U_CHAR * bufferptr;
    206   register JSAMPLE *rescale = source->rescale;
    207   JDIMENSION col;
    208 
    209   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
    210     ERREXIT(cinfo, JERR_INPUT_EOF);
    211   ptr = source->pub.buffer[0];
    212   bufferptr = source->iobuffer;
    213   for (col = cinfo->image_width; col > 0; col--) {
    214     *ptr++ = rescale[UCH(*bufferptr++)];
    215     *ptr++ = rescale[UCH(*bufferptr++)];
    216     *ptr++ = rescale[UCH(*bufferptr++)];
    217   }
    218   return 1;
    219 }
    220 
    221 
    222 METHODDEF(JDIMENSION)
    223 get_raw_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    224 /* This version is for reading raw-byte-format files with maxval = MAXJSAMPLE.
    225  * In this case we just read right into the JSAMPLE buffer!
    226  * Note that same code works for PPM and PGM files.
    227  */
    228 {
    229   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    230 
    231   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
    232     ERREXIT(cinfo, JERR_INPUT_EOF);
    233   return 1;
    234 }
    235 
    236 
    237 METHODDEF(JDIMENSION)
    238 get_word_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    239 /* This version is for reading raw-word-format PGM files with any maxval */
    240 {
    241   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    242   register JSAMPROW ptr;
    243   register U_CHAR * bufferptr;
    244   register JSAMPLE *rescale = source->rescale;
    245   JDIMENSION col;
    246 
    247   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
    248     ERREXIT(cinfo, JERR_INPUT_EOF);
    249   ptr = source->pub.buffer[0];
    250   bufferptr = source->iobuffer;
    251   for (col = cinfo->image_width; col > 0; col--) {
    252     register int temp;
    253     temp  = UCH(*bufferptr++);
    254     temp |= UCH(*bufferptr++) << 8;
    255     *ptr++ = rescale[temp];
    256   }
    257   return 1;
    258 }
    259 
    260 
    261 METHODDEF(JDIMENSION)
    262 get_word_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    263 /* This version is for reading raw-word-format PPM files with any maxval */
    264 {
    265   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    266   register JSAMPROW ptr;
    267   register U_CHAR * bufferptr;
    268   register JSAMPLE *rescale = source->rescale;
    269   JDIMENSION col;
    270 
    271   if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
    272     ERREXIT(cinfo, JERR_INPUT_EOF);
    273   ptr = source->pub.buffer[0];
    274   bufferptr = source->iobuffer;
    275   for (col = cinfo->image_width; col > 0; col--) {
    276     register int temp;
    277     temp  = UCH(*bufferptr++);
    278     temp |= UCH(*bufferptr++) << 8;
    279     *ptr++ = rescale[temp];
    280     temp  = UCH(*bufferptr++);
    281     temp |= UCH(*bufferptr++) << 8;
    282     *ptr++ = rescale[temp];
    283     temp  = UCH(*bufferptr++);
    284     temp |= UCH(*bufferptr++) << 8;
    285     *ptr++ = rescale[temp];
    286   }
    287   return 1;
    288 }
    289 
    290 
    291 /*
    292  * Read the file header; return image size and component count.
    293  */
    294 
    295 METHODDEF(void)
    296 start_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    297 {
    298   ppm_source_ptr source = (ppm_source_ptr) sinfo;
    299   int c;
    300   unsigned int w, h, maxval;
    301   boolean need_iobuffer, use_raw_buffer, need_rescale;
    302 
    303   if (getc(source->pub.input_file) != 'P')
    304     ERREXIT(cinfo, JERR_PPM_NOT);
    305 
    306   c = getc(source->pub.input_file); /* subformat discriminator character */
    307 
    308   /* detect unsupported variants (ie, PBM) before trying to read header */
    309   switch (c) {
    310   case '2':			/* it's a text-format PGM file */
    311   case '3':			/* it's a text-format PPM file */
    312   case '5':			/* it's a raw-format PGM file */
    313   case '6':			/* it's a raw-format PPM file */
    314     break;
    315   default:
    316     ERREXIT(cinfo, JERR_PPM_NOT);
    317     break;
    318   }
    319 
    320   /* fetch the remaining header info */
    321   w = read_pbm_integer(cinfo, source->pub.input_file);
    322   h = read_pbm_integer(cinfo, source->pub.input_file);
    323   maxval = read_pbm_integer(cinfo, source->pub.input_file);
    324 
    325   if (w <= 0 || h <= 0 || maxval <= 0) /* error check */
    326     ERREXIT(cinfo, JERR_PPM_NOT);
    327 
    328   cinfo->data_precision = BITS_IN_JSAMPLE; /* we always rescale data to this */
    329   cinfo->image_width = (JDIMENSION) w;
    330   cinfo->image_height = (JDIMENSION) h;
    331 
    332   /* initialize flags to most common settings */
    333   need_iobuffer = TRUE;		/* do we need an I/O buffer? */
    334   use_raw_buffer = FALSE;	/* do we map input buffer onto I/O buffer? */
    335   need_rescale = TRUE;		/* do we need a rescale array? */
    336 
    337   switch (c) {
    338   case '2':			/* it's a text-format PGM file */
    339     cinfo->input_components = 1;
    340     cinfo->in_color_space = JCS_GRAYSCALE;
    341     TRACEMS2(cinfo, 1, JTRC_PGM_TEXT, w, h);
    342     source->pub.get_pixel_rows = get_text_gray_row;
    343     need_iobuffer = FALSE;
    344     break;
    345 
    346   case '3':			/* it's a text-format PPM file */
    347     cinfo->input_components = 3;
    348     cinfo->in_color_space = JCS_RGB;
    349     TRACEMS2(cinfo, 1, JTRC_PPM_TEXT, w, h);
    350     source->pub.get_pixel_rows = get_text_rgb_row;
    351     need_iobuffer = FALSE;
    352     break;
    353 
    354   case '5':			/* it's a raw-format PGM file */
    355     cinfo->input_components = 1;
    356     cinfo->in_color_space = JCS_GRAYSCALE;
    357     TRACEMS2(cinfo, 1, JTRC_PGM, w, h);
    358     if (maxval > 255) {
    359       source->pub.get_pixel_rows = get_word_gray_row;
    360     } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
    361       source->pub.get_pixel_rows = get_raw_row;
    362       use_raw_buffer = TRUE;
    363       need_rescale = FALSE;
    364     } else {
    365       source->pub.get_pixel_rows = get_scaled_gray_row;
    366     }
    367     break;
    368 
    369   case '6':			/* it's a raw-format PPM file */
    370     cinfo->input_components = 3;
    371     cinfo->in_color_space = JCS_RGB;
    372     TRACEMS2(cinfo, 1, JTRC_PPM, w, h);
    373     if (maxval > 255) {
    374       source->pub.get_pixel_rows = get_word_rgb_row;
    375     } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
    376       source->pub.get_pixel_rows = get_raw_row;
    377       use_raw_buffer = TRUE;
    378       need_rescale = FALSE;
    379     } else {
    380       source->pub.get_pixel_rows = get_scaled_rgb_row;
    381     }
    382     break;
    383   }
    384 
    385   /* Allocate space for I/O buffer: 1 or 3 bytes or words/pixel. */
    386   if (need_iobuffer) {
    387     source->buffer_width = (size_t) w * cinfo->input_components *
    388       ((maxval<=255) ? SIZEOF(U_CHAR) : (2*SIZEOF(U_CHAR)));
    389     source->iobuffer = (U_CHAR *)
    390       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    391 				  source->buffer_width);
    392   }
    393 
    394   /* Create compressor input buffer. */
    395   if (use_raw_buffer) {
    396     /* For unscaled raw-input case, we can just map it onto the I/O buffer. */
    397     /* Synthesize a JSAMPARRAY pointer structure */
    398     /* Cast here implies near->far pointer conversion on PCs */
    399     source->pixrow = (JSAMPROW) source->iobuffer;
    400     source->pub.buffer = & source->pixrow;
    401     source->pub.buffer_height = 1;
    402   } else {
    403     /* Need to translate anyway, so make a separate sample buffer. */
    404     source->pub.buffer = (*cinfo->mem->alloc_sarray)
    405       ((j_common_ptr) cinfo, JPOOL_IMAGE,
    406        (JDIMENSION) w * cinfo->input_components, (JDIMENSION) 1);
    407     source->pub.buffer_height = 1;
    408   }
    409 
    410   /* Compute the rescaling array if required. */
    411   if (need_rescale) {
    412     INT32 val, half_maxval;
    413 
    414     /* On 16-bit-int machines we have to be careful of maxval = 65535 */
    415     source->rescale = (JSAMPLE *)
    416       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    417 				  (size_t) (((long) maxval + 1L) * SIZEOF(JSAMPLE)));
    418     half_maxval = maxval / 2;
    419     for (val = 0; val <= (INT32) maxval; val++) {
    420       /* The multiplication here must be done in 32 bits to avoid overflow */
    421       source->rescale[val] = (JSAMPLE) ((val*MAXJSAMPLE + half_maxval)/maxval);
    422     }
    423   }
    424 }
    425 
    426 
    427 /*
    428  * Finish up at the end of the file.
    429  */
    430 
    431 METHODDEF(void)
    432 finish_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    433 {
    434   /* no work */
    435 }
    436 
    437 
    438 /*
    439  * The module selection routine for PPM format input.
    440  */
    441 
    442 GLOBAL(cjpeg_source_ptr)
    443 jinit_read_ppm (j_compress_ptr cinfo)
    444 {
    445   ppm_source_ptr source;
    446 
    447   /* Create module interface object */
    448   source = (ppm_source_ptr)
    449       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    450 				  SIZEOF(ppm_source_struct));
    451   /* Fill in method ptrs, except get_pixel_rows which start_input sets */
    452   source->pub.start_input = start_input_ppm;
    453   source->pub.finish_input = finish_input_ppm;
    454 
    455   return (cjpeg_source_ptr) source;
    456 }
    457 
    458 #endif /* PPM_SUPPORTED */
    459