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)
pbm_getc(FILE * infile)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)
read_pbm_integer(j_compress_ptr cinfo,FILE * infile)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)
get_text_gray_row(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
get_text_rgb_row(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
get_scaled_gray_row(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
get_scaled_rgb_row(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
get_raw_row(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
get_word_gray_row(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
get_word_rgb_row(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
start_input_ppm(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
finish_input_ppm(j_compress_ptr cinfo,cjpeg_source_ptr sinfo)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)
jinit_read_ppm(j_compress_ptr cinfo)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