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ca48cf7 Initial commit based on 1.1.0 release from
Tom Gall authored
1 /*
2 * rdppm.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * Modified 2009 by Bill Allombert, Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains routines to read input images in PPM/PGM format.
10 * The extended 2-byte-per-sample raw PPM/PGM formats are supported.
11 * The PBMPLUS library is NOT required to compile this software
12 * (but it is highly useful as a set of PPM image manipulation programs).
13 *
14 * These routines may need modification for non-Unix environments or
15 * specialized applications. As they stand, they assume input from
16 * an ordinary stdio stream. They further assume that reading begins
17 * at the start of the file; start_input may need work if the
18 * user interface has already read some data (e.g., to determine that
19 * the file is indeed PPM format).
20 */
21
22 #include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
23
24 #ifdef PPM_SUPPORTED
25
26
27 /* Portions of this code are based on the PBMPLUS library, which is:
28 **
29 ** Copyright (C) 1988 by Jef Poskanzer.
30 **
31 ** Permission to use, copy, modify, and distribute this software and its
32 ** documentation for any purpose and without fee is hereby granted, provided
33 ** that the above copyright notice appear in all copies and that both that
34 ** copyright notice and this permission notice appear in supporting
35 ** documentation. This software is provided "as is" without express or
36 ** implied warranty.
37 */
38
39
40 /* Macros to deal with unsigned chars as efficiently as compiler allows */
41
42 #ifdef HAVE_UNSIGNED_CHAR
43 typedef unsigned char U_CHAR;
44 #define UCH(x) ((int) (x))
45 #else /* !HAVE_UNSIGNED_CHAR */
46 #ifdef CHAR_IS_UNSIGNED
47 typedef char U_CHAR;
48 #define UCH(x) ((int) (x))
49 #else
50 typedef char U_CHAR;
51 #define UCH(x) ((int) (x) & 0xFF)
52 #endif
53 #endif /* HAVE_UNSIGNED_CHAR */
54
55
56 #define ReadOK(file,buffer,len) (JFREAD(file,buffer,len) == ((size_t) (len)))
57
58
59 /*
60 * On most systems, reading individual bytes with getc() is drastically less
61 * efficient than buffering a row at a time with fread(). On PCs, we must
62 * allocate the buffer in near data space, because we are assuming small-data
63 * memory model, wherein fread() can't reach far memory. If you need to
64 * process very wide images on a PC, you might have to compile in large-memory
65 * model, or else replace fread() with a getc() loop --- which will be much
66 * slower.
67 */
68
69
70 /* Private version of data source object */
71
72 typedef struct {
73 struct cjpeg_source_struct pub; /* public fields */
74
75 U_CHAR *iobuffer; /* non-FAR pointer to I/O buffer */
76 JSAMPROW pixrow; /* FAR pointer to same */
77 size_t buffer_width; /* width of I/O buffer */
78 JSAMPLE *rescale; /* => maxval-remapping array, or NULL */
79 } ppm_source_struct;
80
81 typedef ppm_source_struct * ppm_source_ptr;
82
83
84 LOCAL(int)
85 pbm_getc (FILE * infile)
86 /* Read next char, skipping over any comments */
87 /* A comment/newline sequence is returned as a newline */
88 {
89 register int ch;
90
91 ch = getc(infile);
92 if (ch == '#') {
93 do {
94 ch = getc(infile);
95 } while (ch != '\n' && ch != EOF);
96 }
97 return ch;
98 }
99
100
101 LOCAL(unsigned int)
102 read_pbm_integer (j_compress_ptr cinfo, FILE * infile)
103 /* Read an unsigned decimal integer from the PPM file */
104 /* Swallows one trailing character after the integer */
105 /* Note that on a 16-bit-int machine, only values up to 64k can be read. */
106 /* This should not be a problem in practice. */
107 {
108 register int ch;
109 register unsigned int val;
110
111 /* Skip any leading whitespace */
112 do {
113 ch = pbm_getc(infile);
114 if (ch == EOF)
115 ERREXIT(cinfo, JERR_INPUT_EOF);
116 } while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
117
118 if (ch < '0' || ch > '9')
119 ERREXIT(cinfo, JERR_PPM_NONNUMERIC);
120
121 val = ch - '0';
122 while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {
123 val *= 10;
124 val += ch - '0';
125 }
126 return val;
127 }
128
129
130 /*
131 * Read one row of pixels.
132 *
133 * We provide several different versions depending on input file format.
134 * In all cases, input is scaled to the size of JSAMPLE.
135 *
136 * A really fast path is provided for reading byte/sample raw files with
137 * maxval = MAXJSAMPLE, which is the normal case for 8-bit data.
138 */
139
140
141 METHODDEF(JDIMENSION)
142 get_text_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
143 /* This version is for reading text-format PGM files with any maxval */
144 {
145 ppm_source_ptr source = (ppm_source_ptr) sinfo;
146 FILE * infile = source->pub.input_file;
147 register JSAMPROW ptr;
148 register JSAMPLE *rescale = source->rescale;
149 JDIMENSION col;
150
151 ptr = source->pub.buffer[0];
152 for (col = cinfo->image_width; col > 0; col--) {
153 *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
154 }
155 return 1;
156 }
157
158
159 METHODDEF(JDIMENSION)
160 get_text_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
161 /* This version is for reading text-format PPM files with any maxval */
162 {
163 ppm_source_ptr source = (ppm_source_ptr) sinfo;
164 FILE * infile = source->pub.input_file;
165 register JSAMPROW ptr;
166 register JSAMPLE *rescale = source->rescale;
167 JDIMENSION col;
168
169 ptr = source->pub.buffer[0];
170 for (col = cinfo->image_width; col > 0; col--) {
171 *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
172 *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
173 *ptr++ = rescale[read_pbm_integer(cinfo, infile)];
174 }
175 return 1;
176 }
177
178
179 METHODDEF(JDIMENSION)
180 get_scaled_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
181 /* This version is for reading raw-byte-format PGM files with any maxval */
182 {
183 ppm_source_ptr source = (ppm_source_ptr) sinfo;
184 register JSAMPROW ptr;
185 register U_CHAR * bufferptr;
186 register JSAMPLE *rescale = source->rescale;
187 JDIMENSION col;
188
189 if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
190 ERREXIT(cinfo, JERR_INPUT_EOF);
191 ptr = source->pub.buffer[0];
192 bufferptr = source->iobuffer;
193 for (col = cinfo->image_width; col > 0; col--) {
194 *ptr++ = rescale[UCH(*bufferptr++)];
195 }
196 return 1;
197 }
198
199
200 METHODDEF(JDIMENSION)
201 get_scaled_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
202 /* This version is for reading raw-byte-format PPM files with any maxval */
203 {
204 ppm_source_ptr source = (ppm_source_ptr) sinfo;
205 register JSAMPROW ptr;
206 register U_CHAR * bufferptr;
207 register JSAMPLE *rescale = source->rescale;
208 JDIMENSION col;
209
210 if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
211 ERREXIT(cinfo, JERR_INPUT_EOF);
212 ptr = source->pub.buffer[0];
213 bufferptr = source->iobuffer;
214 for (col = cinfo->image_width; col > 0; col--) {
215 *ptr++ = rescale[UCH(*bufferptr++)];
216 *ptr++ = rescale[UCH(*bufferptr++)];
217 *ptr++ = rescale[UCH(*bufferptr++)];
218 }
219 return 1;
220 }
221
222
223 METHODDEF(JDIMENSION)
224 get_raw_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
225 /* This version is for reading raw-byte-format files with maxval = MAXJSAMPLE.
226 * In this case we just read right into the JSAMPLE buffer!
227 * Note that same code works for PPM and PGM files.
228 */
229 {
230 ppm_source_ptr source = (ppm_source_ptr) sinfo;
231
232 if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
233 ERREXIT(cinfo, JERR_INPUT_EOF);
234 return 1;
235 }
236
237
238 METHODDEF(JDIMENSION)
239 get_word_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
240 /* This version is for reading raw-word-format PGM files with any maxval */
241 {
242 ppm_source_ptr source = (ppm_source_ptr) sinfo;
243 register JSAMPROW ptr;
244 register U_CHAR * bufferptr;
245 register JSAMPLE *rescale = source->rescale;
246 JDIMENSION col;
247
248 if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
249 ERREXIT(cinfo, JERR_INPUT_EOF);
250 ptr = source->pub.buffer[0];
251 bufferptr = source->iobuffer;
252 for (col = cinfo->image_width; col > 0; col--) {
253 register int temp;
254 temp = UCH(*bufferptr++) << 8;
255 temp |= UCH(*bufferptr++);
256 *ptr++ = rescale[temp];
257 }
258 return 1;
259 }
260
261
262 METHODDEF(JDIMENSION)
263 get_word_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
264 /* This version is for reading raw-word-format PPM files with any maxval */
265 {
266 ppm_source_ptr source = (ppm_source_ptr) sinfo;
267 register JSAMPROW ptr;
268 register U_CHAR * bufferptr;
269 register JSAMPLE *rescale = source->rescale;
270 JDIMENSION col;
271
272 if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))
273 ERREXIT(cinfo, JERR_INPUT_EOF);
274 ptr = source->pub.buffer[0];
275 bufferptr = source->iobuffer;
276 for (col = cinfo->image_width; col > 0; col--) {
277 register int temp;
278 temp = UCH(*bufferptr++) << 8;
279 temp |= UCH(*bufferptr++);
280 *ptr++ = rescale[temp];
281 temp = UCH(*bufferptr++) << 8;
282 temp |= UCH(*bufferptr++);
283 *ptr++ = rescale[temp];
284 temp = UCH(*bufferptr++) << 8;
285 temp |= UCH(*bufferptr++);
286 *ptr++ = rescale[temp];
287 }
288 return 1;
289 }
290
291
292 /*
293 * Read the file header; return image size and component count.
294 */
295
296 METHODDEF(void)
297 start_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
298 {
299 ppm_source_ptr source = (ppm_source_ptr) sinfo;
300 int c;
301 unsigned int w, h, maxval;
302 boolean need_iobuffer, use_raw_buffer, need_rescale;
303
304 if (getc(source->pub.input_file) != 'P')
305 ERREXIT(cinfo, JERR_PPM_NOT);
306
307 c = getc(source->pub.input_file); /* subformat discriminator character */
308
309 /* detect unsupported variants (ie, PBM) before trying to read header */
310 switch (c) {
311 case '2': /* it's a text-format PGM file */
312 case '3': /* it's a text-format PPM file */
313 case '5': /* it's a raw-format PGM file */
314 case '6': /* it's a raw-format PPM file */
315 break;
316 default:
317 ERREXIT(cinfo, JERR_PPM_NOT);
318 break;
319 }
320
321 /* fetch the remaining header info */
322 w = read_pbm_integer(cinfo, source->pub.input_file);
323 h = read_pbm_integer(cinfo, source->pub.input_file);
324 maxval = read_pbm_integer(cinfo, source->pub.input_file);
325
326 if (w <= 0 || h <= 0 || maxval <= 0) /* error check */
327 ERREXIT(cinfo, JERR_PPM_NOT);
328
329 cinfo->data_precision = BITS_IN_JSAMPLE; /* we always rescale data to this */
330 cinfo->image_width = (JDIMENSION) w;
331 cinfo->image_height = (JDIMENSION) h;
332
333 /* initialize flags to most common settings */
334 need_iobuffer = TRUE; /* do we need an I/O buffer? */
335 use_raw_buffer = FALSE; /* do we map input buffer onto I/O buffer? */
336 need_rescale = TRUE; /* do we need a rescale array? */
337
338 switch (c) {
339 case '2': /* it's a text-format PGM file */
340 cinfo->input_components = 1;
341 cinfo->in_color_space = JCS_GRAYSCALE;
342 TRACEMS2(cinfo, 1, JTRC_PGM_TEXT, w, h);
343 source->pub.get_pixel_rows = get_text_gray_row;
344 need_iobuffer = FALSE;
345 break;
346
347 case '3': /* it's a text-format PPM file */
348 cinfo->input_components = 3;
349 cinfo->in_color_space = JCS_RGB;
350 TRACEMS2(cinfo, 1, JTRC_PPM_TEXT, w, h);
351 source->pub.get_pixel_rows = get_text_rgb_row;
352 need_iobuffer = FALSE;
353 break;
354
355 case '5': /* it's a raw-format PGM file */
356 cinfo->input_components = 1;
357 cinfo->in_color_space = JCS_GRAYSCALE;
358 TRACEMS2(cinfo, 1, JTRC_PGM, w, h);
359 if (maxval > 255) {
360 source->pub.get_pixel_rows = get_word_gray_row;
361 } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
362 source->pub.get_pixel_rows = get_raw_row;
363 use_raw_buffer = TRUE;
364 need_rescale = FALSE;
365 } else {
366 source->pub.get_pixel_rows = get_scaled_gray_row;
367 }
368 break;
369
370 case '6': /* it's a raw-format PPM file */
371 cinfo->input_components = 3;
372 cinfo->in_color_space = JCS_RGB;
373 TRACEMS2(cinfo, 1, JTRC_PPM, w, h);
374 if (maxval > 255) {
375 source->pub.get_pixel_rows = get_word_rgb_row;
376 } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {
377 source->pub.get_pixel_rows = get_raw_row;
378 use_raw_buffer = TRUE;
379 need_rescale = FALSE;
380 } else {
381 source->pub.get_pixel_rows = get_scaled_rgb_row;
382 }
383 break;
384 }
385
386 /* Allocate space for I/O buffer: 1 or 3 bytes or words/pixel. */
387 if (need_iobuffer) {
388 source->buffer_width = (size_t) w * cinfo->input_components *
389 ((maxval<=255) ? SIZEOF(U_CHAR) : (2*SIZEOF(U_CHAR)));
390 source->iobuffer = (U_CHAR *)
391 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
392 source->buffer_width);
393 }
394
395 /* Create compressor input buffer. */
396 if (use_raw_buffer) {
397 /* For unscaled raw-input case, we can just map it onto the I/O buffer. */
398 /* Synthesize a JSAMPARRAY pointer structure */
399 /* Cast here implies near->far pointer conversion on PCs */
400 source->pixrow = (JSAMPROW) source->iobuffer;
401 source->pub.buffer = & source->pixrow;
402 source->pub.buffer_height = 1;
403 } else {
404 /* Need to translate anyway, so make a separate sample buffer. */
405 source->pub.buffer = (*cinfo->mem->alloc_sarray)
406 ((j_common_ptr) cinfo, JPOOL_IMAGE,
407 (JDIMENSION) w * cinfo->input_components, (JDIMENSION) 1);
408 source->pub.buffer_height = 1;
409 }
410
411 /* Compute the rescaling array if required. */
412 if (need_rescale) {
413 INT32 val, half_maxval;
414
415 /* On 16-bit-int machines we have to be careful of maxval = 65535 */
416 source->rescale = (JSAMPLE *)
417 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
418 (size_t) (((long) maxval + 1L) * SIZEOF(JSAMPLE)));
419 half_maxval = maxval / 2;
420 for (val = 0; val <= (INT32) maxval; val++) {
421 /* The multiplication here must be done in 32 bits to avoid overflow */
422 source->rescale[val] = (JSAMPLE) ((val*MAXJSAMPLE + half_maxval)/maxval);
423 }
424 }
425 }
426
427
428 /*
429 * Finish up at the end of the file.
430 */
431
432 METHODDEF(void)
433 finish_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
434 {
435 /* no work */
436 }
437
438
439 /*
440 * The module selection routine for PPM format input.
441 */
442
443 GLOBAL(cjpeg_source_ptr)
444 jinit_read_ppm (j_compress_ptr cinfo)
445 {
446 ppm_source_ptr source;
447
448 /* Create module interface object */
449 source = (ppm_source_ptr)
450 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
451 SIZEOF(ppm_source_struct));
452 /* Fill in method ptrs, except get_pixel_rows which start_input sets */
453 source->pub.start_input = start_input_ppm;
454 source->pub.finish_input = finish_input_ppm;
455
456 return (cjpeg_source_ptr) source;
457 }
458
459 #endif /* PPM_SUPPORTED */
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