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
