diff options
Diffstat (limited to '')
-rw-r--r-- | libraries/irrlicht-1.8/source/Irrlicht/libpng/png.c | 2870 |
1 files changed, 2870 insertions, 0 deletions
diff --git a/libraries/irrlicht-1.8/source/Irrlicht/libpng/png.c b/libraries/irrlicht-1.8/source/Irrlicht/libpng/png.c new file mode 100644 index 0000000..5a490b2 --- /dev/null +++ b/libraries/irrlicht-1.8/source/Irrlicht/libpng/png.c | |||
@@ -0,0 +1,2870 @@ | |||
1 | |||
2 | /* png.c - location for general purpose libpng functions | ||
3 | * | ||
4 | * Last changed in libpng 1.5.7 [December 15, 2011] | ||
5 | * Copyright (c) 1998-2011 Glenn Randers-Pehrson | ||
6 | * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) | ||
7 | * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) | ||
8 | * | ||
9 | * This code is released under the libpng license. | ||
10 | * For conditions of distribution and use, see the disclaimer | ||
11 | * and license in png.h | ||
12 | */ | ||
13 | |||
14 | #include "pngpriv.h" | ||
15 | |||
16 | /* Generate a compiler error if there is an old png.h in the search path. */ | ||
17 | typedef png_libpng_version_1_5_9 Your_png_h_is_not_version_1_5_9; | ||
18 | |||
19 | /* Tells libpng that we have already handled the first "num_bytes" bytes | ||
20 | * of the PNG file signature. If the PNG data is embedded into another | ||
21 | * stream we can set num_bytes = 8 so that libpng will not attempt to read | ||
22 | * or write any of the magic bytes before it starts on the IHDR. | ||
23 | */ | ||
24 | |||
25 | #ifdef PNG_READ_SUPPORTED | ||
26 | void PNGAPI | ||
27 | png_set_sig_bytes(png_structp png_ptr, int num_bytes) | ||
28 | { | ||
29 | png_debug(1, "in png_set_sig_bytes"); | ||
30 | |||
31 | if (png_ptr == NULL) | ||
32 | return; | ||
33 | |||
34 | if (num_bytes > 8) | ||
35 | png_error(png_ptr, "Too many bytes for PNG signature"); | ||
36 | |||
37 | png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes); | ||
38 | } | ||
39 | |||
40 | /* Checks whether the supplied bytes match the PNG signature. We allow | ||
41 | * checking less than the full 8-byte signature so that those apps that | ||
42 | * already read the first few bytes of a file to determine the file type | ||
43 | * can simply check the remaining bytes for extra assurance. Returns | ||
44 | * an integer less than, equal to, or greater than zero if sig is found, | ||
45 | * respectively, to be less than, to match, or be greater than the correct | ||
46 | * PNG signature (this is the same behavior as strcmp, memcmp, etc). | ||
47 | */ | ||
48 | int PNGAPI | ||
49 | png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check) | ||
50 | { | ||
51 | png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; | ||
52 | |||
53 | if (num_to_check > 8) | ||
54 | num_to_check = 8; | ||
55 | |||
56 | else if (num_to_check < 1) | ||
57 | return (-1); | ||
58 | |||
59 | if (start > 7) | ||
60 | return (-1); | ||
61 | |||
62 | if (start + num_to_check > 8) | ||
63 | num_to_check = 8 - start; | ||
64 | |||
65 | return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check))); | ||
66 | } | ||
67 | |||
68 | #endif /* PNG_READ_SUPPORTED */ | ||
69 | |||
70 | #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) | ||
71 | /* Function to allocate memory for zlib */ | ||
72 | PNG_FUNCTION(voidpf /* PRIVATE */, | ||
73 | png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED) | ||
74 | { | ||
75 | png_voidp ptr; | ||
76 | png_structp p=(png_structp)png_ptr; | ||
77 | png_uint_32 save_flags=p->flags; | ||
78 | png_alloc_size_t num_bytes; | ||
79 | |||
80 | if (png_ptr == NULL) | ||
81 | return (NULL); | ||
82 | |||
83 | if (items > PNG_UINT_32_MAX/size) | ||
84 | { | ||
85 | png_warning (p, "Potential overflow in png_zalloc()"); | ||
86 | return (NULL); | ||
87 | } | ||
88 | num_bytes = (png_alloc_size_t)items * size; | ||
89 | |||
90 | p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK; | ||
91 | ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes); | ||
92 | p->flags=save_flags; | ||
93 | |||
94 | return ((voidpf)ptr); | ||
95 | } | ||
96 | |||
97 | /* Function to free memory for zlib */ | ||
98 | void /* PRIVATE */ | ||
99 | png_zfree(voidpf png_ptr, voidpf ptr) | ||
100 | { | ||
101 | png_free((png_structp)png_ptr, (png_voidp)ptr); | ||
102 | } | ||
103 | |||
104 | /* Reset the CRC variable to 32 bits of 1's. Care must be taken | ||
105 | * in case CRC is > 32 bits to leave the top bits 0. | ||
106 | */ | ||
107 | void /* PRIVATE */ | ||
108 | png_reset_crc(png_structp png_ptr) | ||
109 | { | ||
110 | /* The cast is safe because the crc is a 32 bit value. */ | ||
111 | png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0); | ||
112 | } | ||
113 | |||
114 | /* Calculate the CRC over a section of data. We can only pass as | ||
115 | * much data to this routine as the largest single buffer size. We | ||
116 | * also check that this data will actually be used before going to the | ||
117 | * trouble of calculating it. | ||
118 | */ | ||
119 | void /* PRIVATE */ | ||
120 | png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length) | ||
121 | { | ||
122 | int need_crc = 1; | ||
123 | |||
124 | if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name)) | ||
125 | { | ||
126 | if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) == | ||
127 | (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN)) | ||
128 | need_crc = 0; | ||
129 | } | ||
130 | |||
131 | else /* critical */ | ||
132 | { | ||
133 | if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) | ||
134 | need_crc = 0; | ||
135 | } | ||
136 | |||
137 | /* 'uLong' is defined as unsigned long, this means that on some systems it is | ||
138 | * a 64 bit value. crc32, however, returns 32 bits so the following cast is | ||
139 | * safe. 'uInt' may be no more than 16 bits, so it is necessary to perform a | ||
140 | * loop here. | ||
141 | */ | ||
142 | if (need_crc && length > 0) | ||
143 | { | ||
144 | uLong crc = png_ptr->crc; /* Should never issue a warning */ | ||
145 | |||
146 | do | ||
147 | { | ||
148 | uInt safeLength = (uInt)length; | ||
149 | if (safeLength == 0) | ||
150 | safeLength = (uInt)-1; /* evil, but safe */ | ||
151 | |||
152 | crc = crc32(crc, ptr, safeLength); | ||
153 | |||
154 | /* The following should never issue compiler warnings, if they do the | ||
155 | * target system has characteristics that will probably violate other | ||
156 | * assumptions within the libpng code. | ||
157 | */ | ||
158 | ptr += safeLength; | ||
159 | length -= safeLength; | ||
160 | } | ||
161 | while (length > 0); | ||
162 | |||
163 | /* And the following is always safe because the crc is only 32 bits. */ | ||
164 | png_ptr->crc = (png_uint_32)crc; | ||
165 | } | ||
166 | } | ||
167 | |||
168 | /* Check a user supplied version number, called from both read and write | ||
169 | * functions that create a png_struct | ||
170 | */ | ||
171 | int | ||
172 | png_user_version_check(png_structp png_ptr, png_const_charp user_png_ver) | ||
173 | { | ||
174 | if (user_png_ver) | ||
175 | { | ||
176 | int i = 0; | ||
177 | |||
178 | do | ||
179 | { | ||
180 | if (user_png_ver[i] != png_libpng_ver[i]) | ||
181 | png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; | ||
182 | } while (png_libpng_ver[i++]); | ||
183 | } | ||
184 | |||
185 | else | ||
186 | png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; | ||
187 | |||
188 | if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) | ||
189 | { | ||
190 | /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so | ||
191 | * we must recompile any applications that use any older library version. | ||
192 | * For versions after libpng 1.0, we will be compatible, so we need | ||
193 | * only check the first digit. | ||
194 | */ | ||
195 | if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] || | ||
196 | (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) || | ||
197 | (user_png_ver[0] == '0' && user_png_ver[2] < '9')) | ||
198 | { | ||
199 | #ifdef PNG_WARNINGS_SUPPORTED | ||
200 | size_t pos = 0; | ||
201 | char m[128]; | ||
202 | |||
203 | pos = png_safecat(m, sizeof m, pos, "Application built with libpng-"); | ||
204 | pos = png_safecat(m, sizeof m, pos, user_png_ver); | ||
205 | pos = png_safecat(m, sizeof m, pos, " but running with "); | ||
206 | pos = png_safecat(m, sizeof m, pos, png_libpng_ver); | ||
207 | |||
208 | png_warning(png_ptr, m); | ||
209 | #endif | ||
210 | |||
211 | #ifdef PNG_ERROR_NUMBERS_SUPPORTED | ||
212 | png_ptr->flags = 0; | ||
213 | #endif | ||
214 | |||
215 | return 0; | ||
216 | } | ||
217 | } | ||
218 | |||
219 | /* Success return. */ | ||
220 | return 1; | ||
221 | } | ||
222 | |||
223 | /* Allocate the memory for an info_struct for the application. We don't | ||
224 | * really need the png_ptr, but it could potentially be useful in the | ||
225 | * future. This should be used in favour of malloc(png_sizeof(png_info)) | ||
226 | * and png_info_init() so that applications that want to use a shared | ||
227 | * libpng don't have to be recompiled if png_info changes size. | ||
228 | */ | ||
229 | PNG_FUNCTION(png_infop,PNGAPI | ||
230 | png_create_info_struct,(png_structp png_ptr),PNG_ALLOCATED) | ||
231 | { | ||
232 | png_infop info_ptr; | ||
233 | |||
234 | png_debug(1, "in png_create_info_struct"); | ||
235 | |||
236 | if (png_ptr == NULL) | ||
237 | return (NULL); | ||
238 | |||
239 | #ifdef PNG_USER_MEM_SUPPORTED | ||
240 | info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO, | ||
241 | png_ptr->malloc_fn, png_ptr->mem_ptr); | ||
242 | #else | ||
243 | info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO); | ||
244 | #endif | ||
245 | if (info_ptr != NULL) | ||
246 | png_info_init_3(&info_ptr, png_sizeof(png_info)); | ||
247 | |||
248 | return (info_ptr); | ||
249 | } | ||
250 | |||
251 | /* This function frees the memory associated with a single info struct. | ||
252 | * Normally, one would use either png_destroy_read_struct() or | ||
253 | * png_destroy_write_struct() to free an info struct, but this may be | ||
254 | * useful for some applications. | ||
255 | */ | ||
256 | void PNGAPI | ||
257 | png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr) | ||
258 | { | ||
259 | png_infop info_ptr = NULL; | ||
260 | |||
261 | png_debug(1, "in png_destroy_info_struct"); | ||
262 | |||
263 | if (png_ptr == NULL) | ||
264 | return; | ||
265 | |||
266 | if (info_ptr_ptr != NULL) | ||
267 | info_ptr = *info_ptr_ptr; | ||
268 | |||
269 | if (info_ptr != NULL) | ||
270 | { | ||
271 | png_info_destroy(png_ptr, info_ptr); | ||
272 | |||
273 | #ifdef PNG_USER_MEM_SUPPORTED | ||
274 | png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn, | ||
275 | png_ptr->mem_ptr); | ||
276 | #else | ||
277 | png_destroy_struct((png_voidp)info_ptr); | ||
278 | #endif | ||
279 | *info_ptr_ptr = NULL; | ||
280 | } | ||
281 | } | ||
282 | |||
283 | /* Initialize the info structure. This is now an internal function (0.89) | ||
284 | * and applications using it are urged to use png_create_info_struct() | ||
285 | * instead. | ||
286 | */ | ||
287 | |||
288 | void PNGAPI | ||
289 | png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size) | ||
290 | { | ||
291 | png_infop info_ptr = *ptr_ptr; | ||
292 | |||
293 | png_debug(1, "in png_info_init_3"); | ||
294 | |||
295 | if (info_ptr == NULL) | ||
296 | return; | ||
297 | |||
298 | if (png_sizeof(png_info) > png_info_struct_size) | ||
299 | { | ||
300 | png_destroy_struct(info_ptr); | ||
301 | info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO); | ||
302 | *ptr_ptr = info_ptr; | ||
303 | } | ||
304 | |||
305 | /* Set everything to 0 */ | ||
306 | png_memset(info_ptr, 0, png_sizeof(png_info)); | ||
307 | } | ||
308 | |||
309 | void PNGAPI | ||
310 | png_data_freer(png_structp png_ptr, png_infop info_ptr, | ||
311 | int freer, png_uint_32 mask) | ||
312 | { | ||
313 | png_debug(1, "in png_data_freer"); | ||
314 | |||
315 | if (png_ptr == NULL || info_ptr == NULL) | ||
316 | return; | ||
317 | |||
318 | if (freer == PNG_DESTROY_WILL_FREE_DATA) | ||
319 | info_ptr->free_me |= mask; | ||
320 | |||
321 | else if (freer == PNG_USER_WILL_FREE_DATA) | ||
322 | info_ptr->free_me &= ~mask; | ||
323 | |||
324 | else | ||
325 | png_warning(png_ptr, | ||
326 | "Unknown freer parameter in png_data_freer"); | ||
327 | } | ||
328 | |||
329 | void PNGAPI | ||
330 | png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask, | ||
331 | int num) | ||
332 | { | ||
333 | png_debug(1, "in png_free_data"); | ||
334 | |||
335 | if (png_ptr == NULL || info_ptr == NULL) | ||
336 | return; | ||
337 | |||
338 | #ifdef PNG_TEXT_SUPPORTED | ||
339 | /* Free text item num or (if num == -1) all text items */ | ||
340 | if ((mask & PNG_FREE_TEXT) & info_ptr->free_me) | ||
341 | { | ||
342 | if (num != -1) | ||
343 | { | ||
344 | if (info_ptr->text && info_ptr->text[num].key) | ||
345 | { | ||
346 | png_free(png_ptr, info_ptr->text[num].key); | ||
347 | info_ptr->text[num].key = NULL; | ||
348 | } | ||
349 | } | ||
350 | |||
351 | else | ||
352 | { | ||
353 | int i; | ||
354 | for (i = 0; i < info_ptr->num_text; i++) | ||
355 | png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i); | ||
356 | png_free(png_ptr, info_ptr->text); | ||
357 | info_ptr->text = NULL; | ||
358 | info_ptr->num_text=0; | ||
359 | } | ||
360 | } | ||
361 | #endif | ||
362 | |||
363 | #ifdef PNG_tRNS_SUPPORTED | ||
364 | /* Free any tRNS entry */ | ||
365 | if ((mask & PNG_FREE_TRNS) & info_ptr->free_me) | ||
366 | { | ||
367 | png_free(png_ptr, info_ptr->trans_alpha); | ||
368 | info_ptr->trans_alpha = NULL; | ||
369 | info_ptr->valid &= ~PNG_INFO_tRNS; | ||
370 | } | ||
371 | #endif | ||
372 | |||
373 | #ifdef PNG_sCAL_SUPPORTED | ||
374 | /* Free any sCAL entry */ | ||
375 | if ((mask & PNG_FREE_SCAL) & info_ptr->free_me) | ||
376 | { | ||
377 | png_free(png_ptr, info_ptr->scal_s_width); | ||
378 | png_free(png_ptr, info_ptr->scal_s_height); | ||
379 | info_ptr->scal_s_width = NULL; | ||
380 | info_ptr->scal_s_height = NULL; | ||
381 | info_ptr->valid &= ~PNG_INFO_sCAL; | ||
382 | } | ||
383 | #endif | ||
384 | |||
385 | #ifdef PNG_pCAL_SUPPORTED | ||
386 | /* Free any pCAL entry */ | ||
387 | if ((mask & PNG_FREE_PCAL) & info_ptr->free_me) | ||
388 | { | ||
389 | png_free(png_ptr, info_ptr->pcal_purpose); | ||
390 | png_free(png_ptr, info_ptr->pcal_units); | ||
391 | info_ptr->pcal_purpose = NULL; | ||
392 | info_ptr->pcal_units = NULL; | ||
393 | if (info_ptr->pcal_params != NULL) | ||
394 | { | ||
395 | int i; | ||
396 | for (i = 0; i < (int)info_ptr->pcal_nparams; i++) | ||
397 | { | ||
398 | png_free(png_ptr, info_ptr->pcal_params[i]); | ||
399 | info_ptr->pcal_params[i] = NULL; | ||
400 | } | ||
401 | png_free(png_ptr, info_ptr->pcal_params); | ||
402 | info_ptr->pcal_params = NULL; | ||
403 | } | ||
404 | info_ptr->valid &= ~PNG_INFO_pCAL; | ||
405 | } | ||
406 | #endif | ||
407 | |||
408 | #ifdef PNG_iCCP_SUPPORTED | ||
409 | /* Free any iCCP entry */ | ||
410 | if ((mask & PNG_FREE_ICCP) & info_ptr->free_me) | ||
411 | { | ||
412 | png_free(png_ptr, info_ptr->iccp_name); | ||
413 | png_free(png_ptr, info_ptr->iccp_profile); | ||
414 | info_ptr->iccp_name = NULL; | ||
415 | info_ptr->iccp_profile = NULL; | ||
416 | info_ptr->valid &= ~PNG_INFO_iCCP; | ||
417 | } | ||
418 | #endif | ||
419 | |||
420 | #ifdef PNG_sPLT_SUPPORTED | ||
421 | /* Free a given sPLT entry, or (if num == -1) all sPLT entries */ | ||
422 | if ((mask & PNG_FREE_SPLT) & info_ptr->free_me) | ||
423 | { | ||
424 | if (num != -1) | ||
425 | { | ||
426 | if (info_ptr->splt_palettes) | ||
427 | { | ||
428 | png_free(png_ptr, info_ptr->splt_palettes[num].name); | ||
429 | png_free(png_ptr, info_ptr->splt_palettes[num].entries); | ||
430 | info_ptr->splt_palettes[num].name = NULL; | ||
431 | info_ptr->splt_palettes[num].entries = NULL; | ||
432 | } | ||
433 | } | ||
434 | |||
435 | else | ||
436 | { | ||
437 | if (info_ptr->splt_palettes_num) | ||
438 | { | ||
439 | int i; | ||
440 | for (i = 0; i < (int)info_ptr->splt_palettes_num; i++) | ||
441 | png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i); | ||
442 | |||
443 | png_free(png_ptr, info_ptr->splt_palettes); | ||
444 | info_ptr->splt_palettes = NULL; | ||
445 | info_ptr->splt_palettes_num = 0; | ||
446 | } | ||
447 | info_ptr->valid &= ~PNG_INFO_sPLT; | ||
448 | } | ||
449 | } | ||
450 | #endif | ||
451 | |||
452 | #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED | ||
453 | if (png_ptr->unknown_chunk.data) | ||
454 | { | ||
455 | png_free(png_ptr, png_ptr->unknown_chunk.data); | ||
456 | png_ptr->unknown_chunk.data = NULL; | ||
457 | } | ||
458 | |||
459 | if ((mask & PNG_FREE_UNKN) & info_ptr->free_me) | ||
460 | { | ||
461 | if (num != -1) | ||
462 | { | ||
463 | if (info_ptr->unknown_chunks) | ||
464 | { | ||
465 | png_free(png_ptr, info_ptr->unknown_chunks[num].data); | ||
466 | info_ptr->unknown_chunks[num].data = NULL; | ||
467 | } | ||
468 | } | ||
469 | |||
470 | else | ||
471 | { | ||
472 | int i; | ||
473 | |||
474 | if (info_ptr->unknown_chunks_num) | ||
475 | { | ||
476 | for (i = 0; i < info_ptr->unknown_chunks_num; i++) | ||
477 | png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i); | ||
478 | |||
479 | png_free(png_ptr, info_ptr->unknown_chunks); | ||
480 | info_ptr->unknown_chunks = NULL; | ||
481 | info_ptr->unknown_chunks_num = 0; | ||
482 | } | ||
483 | } | ||
484 | } | ||
485 | #endif | ||
486 | |||
487 | #ifdef PNG_hIST_SUPPORTED | ||
488 | /* Free any hIST entry */ | ||
489 | if ((mask & PNG_FREE_HIST) & info_ptr->free_me) | ||
490 | { | ||
491 | png_free(png_ptr, info_ptr->hist); | ||
492 | info_ptr->hist = NULL; | ||
493 | info_ptr->valid &= ~PNG_INFO_hIST; | ||
494 | } | ||
495 | #endif | ||
496 | |||
497 | /* Free any PLTE entry that was internally allocated */ | ||
498 | if ((mask & PNG_FREE_PLTE) & info_ptr->free_me) | ||
499 | { | ||
500 | png_zfree(png_ptr, info_ptr->palette); | ||
501 | info_ptr->palette = NULL; | ||
502 | info_ptr->valid &= ~PNG_INFO_PLTE; | ||
503 | info_ptr->num_palette = 0; | ||
504 | } | ||
505 | |||
506 | #ifdef PNG_INFO_IMAGE_SUPPORTED | ||
507 | /* Free any image bits attached to the info structure */ | ||
508 | if ((mask & PNG_FREE_ROWS) & info_ptr->free_me) | ||
509 | { | ||
510 | if (info_ptr->row_pointers) | ||
511 | { | ||
512 | int row; | ||
513 | for (row = 0; row < (int)info_ptr->height; row++) | ||
514 | { | ||
515 | png_free(png_ptr, info_ptr->row_pointers[row]); | ||
516 | info_ptr->row_pointers[row] = NULL; | ||
517 | } | ||
518 | png_free(png_ptr, info_ptr->row_pointers); | ||
519 | info_ptr->row_pointers = NULL; | ||
520 | } | ||
521 | info_ptr->valid &= ~PNG_INFO_IDAT; | ||
522 | } | ||
523 | #endif | ||
524 | |||
525 | if (num != -1) | ||
526 | mask &= ~PNG_FREE_MUL; | ||
527 | |||
528 | info_ptr->free_me &= ~mask; | ||
529 | } | ||
530 | |||
531 | /* This is an internal routine to free any memory that the info struct is | ||
532 | * pointing to before re-using it or freeing the struct itself. Recall | ||
533 | * that png_free() checks for NULL pointers for us. | ||
534 | */ | ||
535 | void /* PRIVATE */ | ||
536 | png_info_destroy(png_structp png_ptr, png_infop info_ptr) | ||
537 | { | ||
538 | png_debug(1, "in png_info_destroy"); | ||
539 | |||
540 | png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1); | ||
541 | |||
542 | #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | ||
543 | if (png_ptr->num_chunk_list) | ||
544 | { | ||
545 | png_free(png_ptr, png_ptr->chunk_list); | ||
546 | png_ptr->chunk_list = NULL; | ||
547 | png_ptr->num_chunk_list = 0; | ||
548 | } | ||
549 | #endif | ||
550 | |||
551 | png_info_init_3(&info_ptr, png_sizeof(png_info)); | ||
552 | } | ||
553 | #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ | ||
554 | |||
555 | /* This function returns a pointer to the io_ptr associated with the user | ||
556 | * functions. The application should free any memory associated with this | ||
557 | * pointer before png_write_destroy() or png_read_destroy() are called. | ||
558 | */ | ||
559 | png_voidp PNGAPI | ||
560 | png_get_io_ptr(png_structp png_ptr) | ||
561 | { | ||
562 | if (png_ptr == NULL) | ||
563 | return (NULL); | ||
564 | |||
565 | return (png_ptr->io_ptr); | ||
566 | } | ||
567 | |||
568 | #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) | ||
569 | # ifdef PNG_STDIO_SUPPORTED | ||
570 | /* Initialize the default input/output functions for the PNG file. If you | ||
571 | * use your own read or write routines, you can call either png_set_read_fn() | ||
572 | * or png_set_write_fn() instead of png_init_io(). If you have defined | ||
573 | * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a | ||
574 | * function of your own because "FILE *" isn't necessarily available. | ||
575 | */ | ||
576 | void PNGAPI | ||
577 | png_init_io(png_structp png_ptr, png_FILE_p fp) | ||
578 | { | ||
579 | png_debug(1, "in png_init_io"); | ||
580 | |||
581 | if (png_ptr == NULL) | ||
582 | return; | ||
583 | |||
584 | png_ptr->io_ptr = (png_voidp)fp; | ||
585 | } | ||
586 | # endif | ||
587 | |||
588 | # ifdef PNG_TIME_RFC1123_SUPPORTED | ||
589 | /* Convert the supplied time into an RFC 1123 string suitable for use in | ||
590 | * a "Creation Time" or other text-based time string. | ||
591 | */ | ||
592 | png_const_charp PNGAPI | ||
593 | png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime) | ||
594 | { | ||
595 | static PNG_CONST char short_months[12][4] = | ||
596 | {"Jan", "Feb", "Mar", "Apr", "May", "Jun", | ||
597 | "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; | ||
598 | |||
599 | if (png_ptr == NULL) | ||
600 | return (NULL); | ||
601 | |||
602 | if (ptime->year > 9999 /* RFC1123 limitation */ || | ||
603 | ptime->month == 0 || ptime->month > 12 || | ||
604 | ptime->day == 0 || ptime->day > 31 || | ||
605 | ptime->hour > 23 || ptime->minute > 59 || | ||
606 | ptime->second > 60) | ||
607 | { | ||
608 | png_warning(png_ptr, "Ignoring invalid time value"); | ||
609 | return (NULL); | ||
610 | } | ||
611 | |||
612 | { | ||
613 | size_t pos = 0; | ||
614 | char number_buf[5]; /* enough for a four-digit year */ | ||
615 | |||
616 | # define APPEND_STRING(string)\ | ||
617 | pos = png_safecat(png_ptr->time_buffer, sizeof png_ptr->time_buffer,\ | ||
618 | pos, (string)) | ||
619 | # define APPEND_NUMBER(format, value)\ | ||
620 | APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value))) | ||
621 | # define APPEND(ch)\ | ||
622 | if (pos < (sizeof png_ptr->time_buffer)-1)\ | ||
623 | png_ptr->time_buffer[pos++] = (ch) | ||
624 | |||
625 | APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day); | ||
626 | APPEND(' '); | ||
627 | APPEND_STRING(short_months[(ptime->month - 1)]); | ||
628 | APPEND(' '); | ||
629 | APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year); | ||
630 | APPEND(' '); | ||
631 | APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour); | ||
632 | APPEND(':'); | ||
633 | APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute); | ||
634 | APPEND(':'); | ||
635 | APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second); | ||
636 | APPEND_STRING(" +0000"); /* This reliably terminates the buffer */ | ||
637 | |||
638 | # undef APPEND | ||
639 | # undef APPEND_NUMBER | ||
640 | # undef APPEND_STRING | ||
641 | } | ||
642 | |||
643 | return png_ptr->time_buffer; | ||
644 | } | ||
645 | # endif /* PNG_TIME_RFC1123_SUPPORTED */ | ||
646 | |||
647 | #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ | ||
648 | |||
649 | png_const_charp PNGAPI | ||
650 | png_get_copyright(png_const_structp png_ptr) | ||
651 | { | ||
652 | PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ | ||
653 | #ifdef PNG_STRING_COPYRIGHT | ||
654 | return PNG_STRING_COPYRIGHT | ||
655 | #else | ||
656 | # ifdef __STDC__ | ||
657 | return PNG_STRING_NEWLINE \ | ||
658 | "libpng version 1.5.9 - February 18, 2012" PNG_STRING_NEWLINE \ | ||
659 | "Copyright (c) 1998-2011 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \ | ||
660 | "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \ | ||
661 | "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \ | ||
662 | PNG_STRING_NEWLINE; | ||
663 | # else | ||
664 | return "libpng version 1.5.9 - February 18, 2012\ | ||
665 | Copyright (c) 1998-2011 Glenn Randers-Pehrson\ | ||
666 | Copyright (c) 1996-1997 Andreas Dilger\ | ||
667 | Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc."; | ||
668 | # endif | ||
669 | #endif | ||
670 | } | ||
671 | |||
672 | /* The following return the library version as a short string in the | ||
673 | * format 1.0.0 through 99.99.99zz. To get the version of *.h files | ||
674 | * used with your application, print out PNG_LIBPNG_VER_STRING, which | ||
675 | * is defined in png.h. | ||
676 | * Note: now there is no difference between png_get_libpng_ver() and | ||
677 | * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard, | ||
678 | * it is guaranteed that png.c uses the correct version of png.h. | ||
679 | */ | ||
680 | png_const_charp PNGAPI | ||
681 | png_get_libpng_ver(png_const_structp png_ptr) | ||
682 | { | ||
683 | /* Version of *.c files used when building libpng */ | ||
684 | return png_get_header_ver(png_ptr); | ||
685 | } | ||
686 | |||
687 | png_const_charp PNGAPI | ||
688 | png_get_header_ver(png_const_structp png_ptr) | ||
689 | { | ||
690 | /* Version of *.h files used when building libpng */ | ||
691 | PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ | ||
692 | return PNG_LIBPNG_VER_STRING; | ||
693 | } | ||
694 | |||
695 | png_const_charp PNGAPI | ||
696 | png_get_header_version(png_const_structp png_ptr) | ||
697 | { | ||
698 | /* Returns longer string containing both version and date */ | ||
699 | PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ | ||
700 | #ifdef __STDC__ | ||
701 | return PNG_HEADER_VERSION_STRING | ||
702 | # ifndef PNG_READ_SUPPORTED | ||
703 | " (NO READ SUPPORT)" | ||
704 | # endif | ||
705 | PNG_STRING_NEWLINE; | ||
706 | #else | ||
707 | return PNG_HEADER_VERSION_STRING; | ||
708 | #endif | ||
709 | } | ||
710 | |||
711 | #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | ||
712 | int PNGAPI | ||
713 | png_handle_as_unknown(png_structp png_ptr, png_const_bytep chunk_name) | ||
714 | { | ||
715 | /* Check chunk_name and return "keep" value if it's on the list, else 0 */ | ||
716 | png_const_bytep p, p_end; | ||
717 | |||
718 | if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list <= 0) | ||
719 | return PNG_HANDLE_CHUNK_AS_DEFAULT; | ||
720 | |||
721 | p_end = png_ptr->chunk_list; | ||
722 | p = p_end + png_ptr->num_chunk_list*5; /* beyond end */ | ||
723 | |||
724 | /* The code is the fifth byte after each four byte string. Historically this | ||
725 | * code was always searched from the end of the list, so it should continue | ||
726 | * to do so in case there are duplicated entries. | ||
727 | */ | ||
728 | do /* num_chunk_list > 0, so at least one */ | ||
729 | { | ||
730 | p -= 5; | ||
731 | if (!png_memcmp(chunk_name, p, 4)) | ||
732 | return p[4]; | ||
733 | } | ||
734 | while (p > p_end); | ||
735 | |||
736 | return PNG_HANDLE_CHUNK_AS_DEFAULT; | ||
737 | } | ||
738 | |||
739 | int /* PRIVATE */ | ||
740 | png_chunk_unknown_handling(png_structp png_ptr, png_uint_32 chunk_name) | ||
741 | { | ||
742 | png_byte chunk_string[5]; | ||
743 | |||
744 | PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name); | ||
745 | return png_handle_as_unknown(png_ptr, chunk_string); | ||
746 | } | ||
747 | #endif | ||
748 | |||
749 | #ifdef PNG_READ_SUPPORTED | ||
750 | /* This function, added to libpng-1.0.6g, is untested. */ | ||
751 | int PNGAPI | ||
752 | png_reset_zstream(png_structp png_ptr) | ||
753 | { | ||
754 | if (png_ptr == NULL) | ||
755 | return Z_STREAM_ERROR; | ||
756 | |||
757 | return (inflateReset(&png_ptr->zstream)); | ||
758 | } | ||
759 | #endif /* PNG_READ_SUPPORTED */ | ||
760 | |||
761 | /* This function was added to libpng-1.0.7 */ | ||
762 | png_uint_32 PNGAPI | ||
763 | png_access_version_number(void) | ||
764 | { | ||
765 | /* Version of *.c files used when building libpng */ | ||
766 | return((png_uint_32)PNG_LIBPNG_VER); | ||
767 | } | ||
768 | |||
769 | |||
770 | |||
771 | #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) | ||
772 | /* png_convert_size: a PNGAPI but no longer in png.h, so deleted | ||
773 | * at libpng 1.5.5! | ||
774 | */ | ||
775 | |||
776 | /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */ | ||
777 | # ifdef PNG_CHECK_cHRM_SUPPORTED | ||
778 | |||
779 | int /* PRIVATE */ | ||
780 | png_check_cHRM_fixed(png_structp png_ptr, | ||
781 | png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x, | ||
782 | png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y, | ||
783 | png_fixed_point blue_x, png_fixed_point blue_y) | ||
784 | { | ||
785 | int ret = 1; | ||
786 | unsigned long xy_hi,xy_lo,yx_hi,yx_lo; | ||
787 | |||
788 | png_debug(1, "in function png_check_cHRM_fixed"); | ||
789 | |||
790 | if (png_ptr == NULL) | ||
791 | return 0; | ||
792 | |||
793 | /* (x,y,z) values are first limited to 0..100000 (PNG_FP_1), the white | ||
794 | * y must also be greater than 0. To test for the upper limit calculate | ||
795 | * (PNG_FP_1-y) - x must be <= to this for z to be >= 0 (and the expression | ||
796 | * cannot overflow.) At this point we know x and y are >= 0 and (x+y) is | ||
797 | * <= PNG_FP_1. The previous test on PNG_MAX_UINT_31 is removed because it | ||
798 | * pointless (and it produces compiler warnings!) | ||
799 | */ | ||
800 | if (white_x < 0 || white_y <= 0 || | ||
801 | red_x < 0 || red_y < 0 || | ||
802 | green_x < 0 || green_y < 0 || | ||
803 | blue_x < 0 || blue_y < 0) | ||
804 | { | ||
805 | png_warning(png_ptr, | ||
806 | "Ignoring attempt to set negative chromaticity value"); | ||
807 | ret = 0; | ||
808 | } | ||
809 | /* And (x+y) must be <= PNG_FP_1 (so z is >= 0) */ | ||
810 | if (white_x > PNG_FP_1 - white_y) | ||
811 | { | ||
812 | png_warning(png_ptr, "Invalid cHRM white point"); | ||
813 | ret = 0; | ||
814 | } | ||
815 | |||
816 | if (red_x > PNG_FP_1 - red_y) | ||
817 | { | ||
818 | png_warning(png_ptr, "Invalid cHRM red point"); | ||
819 | ret = 0; | ||
820 | } | ||
821 | |||
822 | if (green_x > PNG_FP_1 - green_y) | ||
823 | { | ||
824 | png_warning(png_ptr, "Invalid cHRM green point"); | ||
825 | ret = 0; | ||
826 | } | ||
827 | |||
828 | if (blue_x > PNG_FP_1 - blue_y) | ||
829 | { | ||
830 | png_warning(png_ptr, "Invalid cHRM blue point"); | ||
831 | ret = 0; | ||
832 | } | ||
833 | |||
834 | png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo); | ||
835 | png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo); | ||
836 | |||
837 | if (xy_hi == yx_hi && xy_lo == yx_lo) | ||
838 | { | ||
839 | png_warning(png_ptr, | ||
840 | "Ignoring attempt to set cHRM RGB triangle with zero area"); | ||
841 | ret = 0; | ||
842 | } | ||
843 | |||
844 | return ret; | ||
845 | } | ||
846 | # endif /* PNG_CHECK_cHRM_SUPPORTED */ | ||
847 | |||
848 | #ifdef PNG_cHRM_SUPPORTED | ||
849 | /* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for | ||
850 | * cHRM, as opposed to using chromaticities. These internal APIs return | ||
851 | * non-zero on a parameter error. The X, Y and Z values are required to be | ||
852 | * positive and less than 1.0. | ||
853 | */ | ||
854 | int png_xy_from_XYZ(png_xy *xy, png_XYZ XYZ) | ||
855 | { | ||
856 | png_int_32 d, dwhite, whiteX, whiteY; | ||
857 | |||
858 | d = XYZ.redX + XYZ.redY + XYZ.redZ; | ||
859 | if (!png_muldiv(&xy->redx, XYZ.redX, PNG_FP_1, d)) return 1; | ||
860 | if (!png_muldiv(&xy->redy, XYZ.redY, PNG_FP_1, d)) return 1; | ||
861 | dwhite = d; | ||
862 | whiteX = XYZ.redX; | ||
863 | whiteY = XYZ.redY; | ||
864 | |||
865 | d = XYZ.greenX + XYZ.greenY + XYZ.greenZ; | ||
866 | if (!png_muldiv(&xy->greenx, XYZ.greenX, PNG_FP_1, d)) return 1; | ||
867 | if (!png_muldiv(&xy->greeny, XYZ.greenY, PNG_FP_1, d)) return 1; | ||
868 | dwhite += d; | ||
869 | whiteX += XYZ.greenX; | ||
870 | whiteY += XYZ.greenY; | ||
871 | |||
872 | d = XYZ.blueX + XYZ.blueY + XYZ.blueZ; | ||
873 | if (!png_muldiv(&xy->bluex, XYZ.blueX, PNG_FP_1, d)) return 1; | ||
874 | if (!png_muldiv(&xy->bluey, XYZ.blueY, PNG_FP_1, d)) return 1; | ||
875 | dwhite += d; | ||
876 | whiteX += XYZ.blueX; | ||
877 | whiteY += XYZ.blueY; | ||
878 | |||
879 | /* The reference white is simply the same of the end-point (X,Y,Z) vectors, | ||
880 | * thus: | ||
881 | */ | ||
882 | if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1; | ||
883 | if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1; | ||
884 | |||
885 | return 0; | ||
886 | } | ||
887 | |||
888 | int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy) | ||
889 | { | ||
890 | png_fixed_point red_inverse, green_inverse, blue_scale; | ||
891 | png_fixed_point left, right, denominator; | ||
892 | |||
893 | /* Check xy and, implicitly, z. Note that wide gamut color spaces typically | ||
894 | * have end points with 0 tristimulus values (these are impossible end | ||
895 | * points, but they are used to cover the possible colors.) | ||
896 | */ | ||
897 | if (xy.redx < 0 || xy.redx > PNG_FP_1) return 1; | ||
898 | if (xy.redy < 0 || xy.redy > PNG_FP_1-xy.redx) return 1; | ||
899 | if (xy.greenx < 0 || xy.greenx > PNG_FP_1) return 1; | ||
900 | if (xy.greeny < 0 || xy.greeny > PNG_FP_1-xy.greenx) return 1; | ||
901 | if (xy.bluex < 0 || xy.bluex > PNG_FP_1) return 1; | ||
902 | if (xy.bluey < 0 || xy.bluey > PNG_FP_1-xy.bluex) return 1; | ||
903 | if (xy.whitex < 0 || xy.whitex > PNG_FP_1) return 1; | ||
904 | if (xy.whitey < 0 || xy.whitey > PNG_FP_1-xy.whitex) return 1; | ||
905 | |||
906 | /* The reverse calculation is more difficult because the original tristimulus | ||
907 | * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8 | ||
908 | * derived values were recorded in the cHRM chunk; | ||
909 | * (red,green,blue,white)x(x,y). This loses one degree of freedom and | ||
910 | * therefore an arbitrary ninth value has to be introduced to undo the | ||
911 | * original transformations. | ||
912 | * | ||
913 | * Think of the original end-points as points in (X,Y,Z) space. The | ||
914 | * chromaticity values (c) have the property: | ||
915 | * | ||
916 | * C | ||
917 | * c = --------- | ||
918 | * X + Y + Z | ||
919 | * | ||
920 | * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the | ||
921 | * three chromaticity values (x,y,z) for each end-point obey the | ||
922 | * relationship: | ||
923 | * | ||
924 | * x + y + z = 1 | ||
925 | * | ||
926 | * This describes the plane in (X,Y,Z) space that intersects each axis at the | ||
927 | * value 1.0; call this the chromaticity plane. Thus the chromaticity | ||
928 | * calculation has scaled each end-point so that it is on the x+y+z=1 plane | ||
929 | * and chromaticity is the intersection of the vector from the origin to the | ||
930 | * (X,Y,Z) value with the chromaticity plane. | ||
931 | * | ||
932 | * To fully invert the chromaticity calculation we would need the three | ||
933 | * end-point scale factors, (red-scale, green-scale, blue-scale), but these | ||
934 | * were not recorded. Instead we calculated the reference white (X,Y,Z) and | ||
935 | * recorded the chromaticity of this. The reference white (X,Y,Z) would have | ||
936 | * given all three of the scale factors since: | ||
937 | * | ||
938 | * color-C = color-c * color-scale | ||
939 | * white-C = red-C + green-C + blue-C | ||
940 | * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale | ||
941 | * | ||
942 | * But cHRM records only white-x and white-y, so we have lost the white scale | ||
943 | * factor: | ||
944 | * | ||
945 | * white-C = white-c*white-scale | ||
946 | * | ||
947 | * To handle this the inverse transformation makes an arbitrary assumption | ||
948 | * about white-scale: | ||
949 | * | ||
950 | * Assume: white-Y = 1.0 | ||
951 | * Hence: white-scale = 1/white-y | ||
952 | * Or: red-Y + green-Y + blue-Y = 1.0 | ||
953 | * | ||
954 | * Notice the last statement of the assumption gives an equation in three of | ||
955 | * the nine values we want to calculate. 8 more equations come from the | ||
956 | * above routine as summarised at the top above (the chromaticity | ||
957 | * calculation): | ||
958 | * | ||
959 | * Given: color-x = color-X / (color-X + color-Y + color-Z) | ||
960 | * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0 | ||
961 | * | ||
962 | * This is 9 simultaneous equations in the 9 variables "color-C" and can be | ||
963 | * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix | ||
964 | * determinants, however this is not as bad as it seems because only 28 of | ||
965 | * the total of 90 terms in the various matrices are non-zero. Nevertheless | ||
966 | * Cramer's rule is notoriously numerically unstable because the determinant | ||
967 | * calculation involves the difference of large, but similar, numbers. It is | ||
968 | * difficult to be sure that the calculation is stable for real world values | ||
969 | * and it is certain that it becomes unstable where the end points are close | ||
970 | * together. | ||
971 | * | ||
972 | * So this code uses the perhaps slighly less optimal but more understandable | ||
973 | * and totally obvious approach of calculating color-scale. | ||
974 | * | ||
975 | * This algorithm depends on the precision in white-scale and that is | ||
976 | * (1/white-y), so we can immediately see that as white-y approaches 0 the | ||
977 | * accuracy inherent in the cHRM chunk drops off substantially. | ||
978 | * | ||
979 | * libpng arithmetic: a simple invertion of the above equations | ||
980 | * ------------------------------------------------------------ | ||
981 | * | ||
982 | * white_scale = 1/white-y | ||
983 | * white-X = white-x * white-scale | ||
984 | * white-Y = 1.0 | ||
985 | * white-Z = (1 - white-x - white-y) * white_scale | ||
986 | * | ||
987 | * white-C = red-C + green-C + blue-C | ||
988 | * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale | ||
989 | * | ||
990 | * This gives us three equations in (red-scale,green-scale,blue-scale) where | ||
991 | * all the coefficients are now known: | ||
992 | * | ||
993 | * red-x*red-scale + green-x*green-scale + blue-x*blue-scale | ||
994 | * = white-x/white-y | ||
995 | * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1 | ||
996 | * red-z*red-scale + green-z*green-scale + blue-z*blue-scale | ||
997 | * = (1 - white-x - white-y)/white-y | ||
998 | * | ||
999 | * In the last equation color-z is (1 - color-x - color-y) so we can add all | ||
1000 | * three equations together to get an alternative third: | ||
1001 | * | ||
1002 | * red-scale + green-scale + blue-scale = 1/white-y = white-scale | ||
1003 | * | ||
1004 | * So now we have a Cramer's rule solution where the determinants are just | ||
1005 | * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve | ||
1006 | * multiplication of three coefficients so we can't guarantee to avoid | ||
1007 | * overflow in the libpng fixed point representation. Using Cramer's rule in | ||
1008 | * floating point is probably a good choice here, but it's not an option for | ||
1009 | * fixed point. Instead proceed to simplify the first two equations by | ||
1010 | * eliminating what is likely to be the largest value, blue-scale: | ||
1011 | * | ||
1012 | * blue-scale = white-scale - red-scale - green-scale | ||
1013 | * | ||
1014 | * Hence: | ||
1015 | * | ||
1016 | * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale = | ||
1017 | * (white-x - blue-x)*white-scale | ||
1018 | * | ||
1019 | * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale = | ||
1020 | * 1 - blue-y*white-scale | ||
1021 | * | ||
1022 | * And now we can trivially solve for (red-scale,green-scale): | ||
1023 | * | ||
1024 | * green-scale = | ||
1025 | * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale | ||
1026 | * ----------------------------------------------------------- | ||
1027 | * green-x - blue-x | ||
1028 | * | ||
1029 | * red-scale = | ||
1030 | * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale | ||
1031 | * --------------------------------------------------------- | ||
1032 | * red-y - blue-y | ||
1033 | * | ||
1034 | * Hence: | ||
1035 | * | ||
1036 | * red-scale = | ||
1037 | * ( (green-x - blue-x) * (white-y - blue-y) - | ||
1038 | * (green-y - blue-y) * (white-x - blue-x) ) / white-y | ||
1039 | * ------------------------------------------------------------------------- | ||
1040 | * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) | ||
1041 | * | ||
1042 | * green-scale = | ||
1043 | * ( (red-y - blue-y) * (white-x - blue-x) - | ||
1044 | * (red-x - blue-x) * (white-y - blue-y) ) / white-y | ||
1045 | * ------------------------------------------------------------------------- | ||
1046 | * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) | ||
1047 | * | ||
1048 | * Accuracy: | ||
1049 | * The input values have 5 decimal digits of accuracy. The values are all in | ||
1050 | * the range 0 < value < 1, so simple products are in the same range but may | ||
1051 | * need up to 10 decimal digits to preserve the original precision and avoid | ||
1052 | * underflow. Because we are using a 32-bit signed representation we cannot | ||
1053 | * match this; the best is a little over 9 decimal digits, less than 10. | ||
1054 | * | ||
1055 | * The approach used here is to preserve the maximum precision within the | ||
1056 | * signed representation. Because the red-scale calculation above uses the | ||
1057 | * difference between two products of values that must be in the range -1..+1 | ||
1058 | * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The | ||
1059 | * factor is irrelevant in the calculation because it is applied to both | ||
1060 | * numerator and denominator. | ||
1061 | * | ||
1062 | * Note that the values of the differences of the products of the | ||
1063 | * chromaticities in the above equations tend to be small, for example for | ||
1064 | * the sRGB chromaticities they are: | ||
1065 | * | ||
1066 | * red numerator: -0.04751 | ||
1067 | * green numerator: -0.08788 | ||
1068 | * denominator: -0.2241 (without white-y multiplication) | ||
1069 | * | ||
1070 | * The resultant Y coefficients from the chromaticities of some widely used | ||
1071 | * color space definitions are (to 15 decimal places): | ||
1072 | * | ||
1073 | * sRGB | ||
1074 | * 0.212639005871510 0.715168678767756 0.072192315360734 | ||
1075 | * Kodak ProPhoto | ||
1076 | * 0.288071128229293 0.711843217810102 0.000085653960605 | ||
1077 | * Adobe RGB | ||
1078 | * 0.297344975250536 0.627363566255466 0.075291458493998 | ||
1079 | * Adobe Wide Gamut RGB | ||
1080 | * 0.258728243040113 0.724682314948566 0.016589442011321 | ||
1081 | */ | ||
1082 | /* By the argument, above overflow should be impossible here. The return | ||
1083 | * value of 2 indicates an internal error to the caller. | ||
1084 | */ | ||
1085 | if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.redy - xy.bluey, 7)) return 2; | ||
1086 | if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.redx - xy.bluex, 7)) return 2; | ||
1087 | denominator = left - right; | ||
1088 | |||
1089 | /* Now find the red numerator. */ | ||
1090 | if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2; | ||
1091 | if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.whitex-xy.bluex, 7)) return 2; | ||
1092 | |||
1093 | /* Overflow is possible here and it indicates an extreme set of PNG cHRM | ||
1094 | * chunk values. This calculation actually returns the reciprocal of the | ||
1095 | * scale value because this allows us to delay the multiplication of white-y | ||
1096 | * into the denominator, which tends to produce a small number. | ||
1097 | */ | ||
1098 | if (!png_muldiv(&red_inverse, xy.whitey, denominator, left-right) || | ||
1099 | red_inverse <= xy.whitey /* r+g+b scales = white scale */) | ||
1100 | return 1; | ||
1101 | |||
1102 | /* Similarly for green_inverse: */ | ||
1103 | if (!png_muldiv(&left, xy.redy-xy.bluey, xy.whitex-xy.bluex, 7)) return 2; | ||
1104 | if (!png_muldiv(&right, xy.redx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2; | ||
1105 | if (!png_muldiv(&green_inverse, xy.whitey, denominator, left-right) || | ||
1106 | green_inverse <= xy.whitey) | ||
1107 | return 1; | ||
1108 | |||
1109 | /* And the blue scale, the checks above guarantee this can't overflow but it | ||
1110 | * can still produce 0 for extreme cHRM values. | ||
1111 | */ | ||
1112 | blue_scale = png_reciprocal(xy.whitey) - png_reciprocal(red_inverse) - | ||
1113 | png_reciprocal(green_inverse); | ||
1114 | if (blue_scale <= 0) return 1; | ||
1115 | |||
1116 | |||
1117 | /* And fill in the png_XYZ: */ | ||
1118 | if (!png_muldiv(&XYZ->redX, xy.redx, PNG_FP_1, red_inverse)) return 1; | ||
1119 | if (!png_muldiv(&XYZ->redY, xy.redy, PNG_FP_1, red_inverse)) return 1; | ||
1120 | if (!png_muldiv(&XYZ->redZ, PNG_FP_1 - xy.redx - xy.redy, PNG_FP_1, | ||
1121 | red_inverse)) | ||
1122 | return 1; | ||
1123 | |||
1124 | if (!png_muldiv(&XYZ->greenX, xy.greenx, PNG_FP_1, green_inverse)) return 1; | ||
1125 | if (!png_muldiv(&XYZ->greenY, xy.greeny, PNG_FP_1, green_inverse)) return 1; | ||
1126 | if (!png_muldiv(&XYZ->greenZ, PNG_FP_1 - xy.greenx - xy.greeny, PNG_FP_1, | ||
1127 | green_inverse)) | ||
1128 | return 1; | ||
1129 | |||
1130 | if (!png_muldiv(&XYZ->blueX, xy.bluex, blue_scale, PNG_FP_1)) return 1; | ||
1131 | if (!png_muldiv(&XYZ->blueY, xy.bluey, blue_scale, PNG_FP_1)) return 1; | ||
1132 | if (!png_muldiv(&XYZ->blueZ, PNG_FP_1 - xy.bluex - xy.bluey, blue_scale, | ||
1133 | PNG_FP_1)) | ||
1134 | return 1; | ||
1135 | |||
1136 | return 0; /*success*/ | ||
1137 | } | ||
1138 | |||
1139 | int png_XYZ_from_xy_checked(png_structp png_ptr, png_XYZ *XYZ, png_xy xy) | ||
1140 | { | ||
1141 | switch (png_XYZ_from_xy(XYZ, xy)) | ||
1142 | { | ||
1143 | case 0: /* success */ | ||
1144 | return 1; | ||
1145 | |||
1146 | case 1: | ||
1147 | /* The chunk may be technically valid, but we got png_fixed_point | ||
1148 | * overflow while trying to get XYZ values out of it. This is | ||
1149 | * entirely benign - the cHRM chunk is pretty extreme. | ||
1150 | */ | ||
1151 | png_warning(png_ptr, | ||
1152 | "extreme cHRM chunk cannot be converted to tristimulus values"); | ||
1153 | break; | ||
1154 | |||
1155 | default: | ||
1156 | /* libpng is broken; this should be a warning but if it happens we | ||
1157 | * want error reports so for the moment it is an error. | ||
1158 | */ | ||
1159 | png_error(png_ptr, "internal error in png_XYZ_from_xy"); | ||
1160 | break; | ||
1161 | } | ||
1162 | |||
1163 | /* ERROR RETURN */ | ||
1164 | return 0; | ||
1165 | } | ||
1166 | #endif | ||
1167 | |||
1168 | void /* PRIVATE */ | ||
1169 | png_check_IHDR(png_structp png_ptr, | ||
1170 | png_uint_32 width, png_uint_32 height, int bit_depth, | ||
1171 | int color_type, int interlace_type, int compression_type, | ||
1172 | int filter_type) | ||
1173 | { | ||
1174 | int error = 0; | ||
1175 | |||
1176 | /* Check for width and height valid values */ | ||
1177 | if (width == 0) | ||
1178 | { | ||
1179 | png_warning(png_ptr, "Image width is zero in IHDR"); | ||
1180 | error = 1; | ||
1181 | } | ||
1182 | |||
1183 | if (height == 0) | ||
1184 | { | ||
1185 | png_warning(png_ptr, "Image height is zero in IHDR"); | ||
1186 | error = 1; | ||
1187 | } | ||
1188 | |||
1189 | # ifdef PNG_SET_USER_LIMITS_SUPPORTED | ||
1190 | if (width > png_ptr->user_width_max) | ||
1191 | |||
1192 | # else | ||
1193 | if (width > PNG_USER_WIDTH_MAX) | ||
1194 | # endif | ||
1195 | { | ||
1196 | png_warning(png_ptr, "Image width exceeds user limit in IHDR"); | ||
1197 | error = 1; | ||
1198 | } | ||
1199 | |||
1200 | # ifdef PNG_SET_USER_LIMITS_SUPPORTED | ||
1201 | if (height > png_ptr->user_height_max) | ||
1202 | # else | ||
1203 | if (height > PNG_USER_HEIGHT_MAX) | ||
1204 | # endif | ||
1205 | { | ||
1206 | png_warning(png_ptr, "Image height exceeds user limit in IHDR"); | ||
1207 | error = 1; | ||
1208 | } | ||
1209 | |||
1210 | if (width > PNG_UINT_31_MAX) | ||
1211 | { | ||
1212 | png_warning(png_ptr, "Invalid image width in IHDR"); | ||
1213 | error = 1; | ||
1214 | } | ||
1215 | |||
1216 | if (height > PNG_UINT_31_MAX) | ||
1217 | { | ||
1218 | png_warning(png_ptr, "Invalid image height in IHDR"); | ||
1219 | error = 1; | ||
1220 | } | ||
1221 | |||
1222 | if (width > (PNG_UINT_32_MAX | ||
1223 | >> 3) /* 8-byte RGBA pixels */ | ||
1224 | - 48 /* bigrowbuf hack */ | ||
1225 | - 1 /* filter byte */ | ||
1226 | - 7*8 /* rounding of width to multiple of 8 pixels */ | ||
1227 | - 8) /* extra max_pixel_depth pad */ | ||
1228 | png_warning(png_ptr, "Width is too large for libpng to process pixels"); | ||
1229 | |||
1230 | /* Check other values */ | ||
1231 | if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 && | ||
1232 | bit_depth != 8 && bit_depth != 16) | ||
1233 | { | ||
1234 | png_warning(png_ptr, "Invalid bit depth in IHDR"); | ||
1235 | error = 1; | ||
1236 | } | ||
1237 | |||
1238 | if (color_type < 0 || color_type == 1 || | ||
1239 | color_type == 5 || color_type > 6) | ||
1240 | { | ||
1241 | png_warning(png_ptr, "Invalid color type in IHDR"); | ||
1242 | error = 1; | ||
1243 | } | ||
1244 | |||
1245 | if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) || | ||
1246 | ((color_type == PNG_COLOR_TYPE_RGB || | ||
1247 | color_type == PNG_COLOR_TYPE_GRAY_ALPHA || | ||
1248 | color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8)) | ||
1249 | { | ||
1250 | png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR"); | ||
1251 | error = 1; | ||
1252 | } | ||
1253 | |||
1254 | if (interlace_type >= PNG_INTERLACE_LAST) | ||
1255 | { | ||
1256 | png_warning(png_ptr, "Unknown interlace method in IHDR"); | ||
1257 | error = 1; | ||
1258 | } | ||
1259 | |||
1260 | if (compression_type != PNG_COMPRESSION_TYPE_BASE) | ||
1261 | { | ||
1262 | png_warning(png_ptr, "Unknown compression method in IHDR"); | ||
1263 | error = 1; | ||
1264 | } | ||
1265 | |||
1266 | # ifdef PNG_MNG_FEATURES_SUPPORTED | ||
1267 | /* Accept filter_method 64 (intrapixel differencing) only if | ||
1268 | * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and | ||
1269 | * 2. Libpng did not read a PNG signature (this filter_method is only | ||
1270 | * used in PNG datastreams that are embedded in MNG datastreams) and | ||
1271 | * 3. The application called png_permit_mng_features with a mask that | ||
1272 | * included PNG_FLAG_MNG_FILTER_64 and | ||
1273 | * 4. The filter_method is 64 and | ||
1274 | * 5. The color_type is RGB or RGBA | ||
1275 | */ | ||
1276 | if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) && | ||
1277 | png_ptr->mng_features_permitted) | ||
1278 | png_warning(png_ptr, "MNG features are not allowed in a PNG datastream"); | ||
1279 | |||
1280 | if (filter_type != PNG_FILTER_TYPE_BASE) | ||
1281 | { | ||
1282 | if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) && | ||
1283 | (filter_type == PNG_INTRAPIXEL_DIFFERENCING) && | ||
1284 | ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && | ||
1285 | (color_type == PNG_COLOR_TYPE_RGB || | ||
1286 | color_type == PNG_COLOR_TYPE_RGB_ALPHA))) | ||
1287 | { | ||
1288 | png_warning(png_ptr, "Unknown filter method in IHDR"); | ||
1289 | error = 1; | ||
1290 | } | ||
1291 | |||
1292 | if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) | ||
1293 | { | ||
1294 | png_warning(png_ptr, "Invalid filter method in IHDR"); | ||
1295 | error = 1; | ||
1296 | } | ||
1297 | } | ||
1298 | |||
1299 | # else | ||
1300 | if (filter_type != PNG_FILTER_TYPE_BASE) | ||
1301 | { | ||
1302 | png_warning(png_ptr, "Unknown filter method in IHDR"); | ||
1303 | error = 1; | ||
1304 | } | ||
1305 | # endif | ||
1306 | |||
1307 | if (error == 1) | ||
1308 | png_error(png_ptr, "Invalid IHDR data"); | ||
1309 | } | ||
1310 | |||
1311 | #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) | ||
1312 | /* ASCII to fp functions */ | ||
1313 | /* Check an ASCII formated floating point value, see the more detailed | ||
1314 | * comments in pngpriv.h | ||
1315 | */ | ||
1316 | /* The following is used internally to preserve the sticky flags */ | ||
1317 | #define png_fp_add(state, flags) ((state) |= (flags)) | ||
1318 | #define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY)) | ||
1319 | |||
1320 | int /* PRIVATE */ | ||
1321 | png_check_fp_number(png_const_charp string, png_size_t size, int *statep, | ||
1322 | png_size_tp whereami) | ||
1323 | { | ||
1324 | int state = *statep; | ||
1325 | png_size_t i = *whereami; | ||
1326 | |||
1327 | while (i < size) | ||
1328 | { | ||
1329 | int type; | ||
1330 | /* First find the type of the next character */ | ||
1331 | switch (string[i]) | ||
1332 | { | ||
1333 | case 43: type = PNG_FP_SAW_SIGN; break; | ||
1334 | case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break; | ||
1335 | case 46: type = PNG_FP_SAW_DOT; break; | ||
1336 | case 48: type = PNG_FP_SAW_DIGIT; break; | ||
1337 | case 49: case 50: case 51: case 52: | ||
1338 | case 53: case 54: case 55: case 56: | ||
1339 | case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break; | ||
1340 | case 69: | ||
1341 | case 101: type = PNG_FP_SAW_E; break; | ||
1342 | default: goto PNG_FP_End; | ||
1343 | } | ||
1344 | |||
1345 | /* Now deal with this type according to the current | ||
1346 | * state, the type is arranged to not overlap the | ||
1347 | * bits of the PNG_FP_STATE. | ||
1348 | */ | ||
1349 | switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY)) | ||
1350 | { | ||
1351 | case PNG_FP_INTEGER + PNG_FP_SAW_SIGN: | ||
1352 | if (state & PNG_FP_SAW_ANY) | ||
1353 | goto PNG_FP_End; /* not a part of the number */ | ||
1354 | |||
1355 | png_fp_add(state, type); | ||
1356 | break; | ||
1357 | |||
1358 | case PNG_FP_INTEGER + PNG_FP_SAW_DOT: | ||
1359 | /* Ok as trailer, ok as lead of fraction. */ | ||
1360 | if (state & PNG_FP_SAW_DOT) /* two dots */ | ||
1361 | goto PNG_FP_End; | ||
1362 | |||
1363 | else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */ | ||
1364 | png_fp_add(state, type); | ||
1365 | |||
1366 | else | ||
1367 | png_fp_set(state, PNG_FP_FRACTION | type); | ||
1368 | |||
1369 | break; | ||
1370 | |||
1371 | case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT: | ||
1372 | if (state & PNG_FP_SAW_DOT) /* delayed fraction */ | ||
1373 | png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT); | ||
1374 | |||
1375 | png_fp_add(state, type | PNG_FP_WAS_VALID); | ||
1376 | |||
1377 | break; | ||
1378 | |||
1379 | case PNG_FP_INTEGER + PNG_FP_SAW_E: | ||
1380 | if ((state & PNG_FP_SAW_DIGIT) == 0) | ||
1381 | goto PNG_FP_End; | ||
1382 | |||
1383 | png_fp_set(state, PNG_FP_EXPONENT); | ||
1384 | |||
1385 | break; | ||
1386 | |||
1387 | /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN: | ||
1388 | goto PNG_FP_End; ** no sign in fraction */ | ||
1389 | |||
1390 | /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT: | ||
1391 | goto PNG_FP_End; ** Because SAW_DOT is always set */ | ||
1392 | |||
1393 | case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT: | ||
1394 | png_fp_add(state, type | PNG_FP_WAS_VALID); | ||
1395 | break; | ||
1396 | |||
1397 | case PNG_FP_FRACTION + PNG_FP_SAW_E: | ||
1398 | /* This is correct because the trailing '.' on an | ||
1399 | * integer is handled above - so we can only get here | ||
1400 | * with the sequence ".E" (with no preceding digits). | ||
1401 | */ | ||
1402 | if ((state & PNG_FP_SAW_DIGIT) == 0) | ||
1403 | goto PNG_FP_End; | ||
1404 | |||
1405 | png_fp_set(state, PNG_FP_EXPONENT); | ||
1406 | |||
1407 | break; | ||
1408 | |||
1409 | case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN: | ||
1410 | if (state & PNG_FP_SAW_ANY) | ||
1411 | goto PNG_FP_End; /* not a part of the number */ | ||
1412 | |||
1413 | png_fp_add(state, PNG_FP_SAW_SIGN); | ||
1414 | |||
1415 | break; | ||
1416 | |||
1417 | /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT: | ||
1418 | goto PNG_FP_End; */ | ||
1419 | |||
1420 | case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT: | ||
1421 | png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID); | ||
1422 | |||
1423 | break; | ||
1424 | |||
1425 | /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E: | ||
1426 | goto PNG_FP_End; */ | ||
1427 | |||
1428 | default: goto PNG_FP_End; /* I.e. break 2 */ | ||
1429 | } | ||
1430 | |||
1431 | /* The character seems ok, continue. */ | ||
1432 | ++i; | ||
1433 | } | ||
1434 | |||
1435 | PNG_FP_End: | ||
1436 | /* Here at the end, update the state and return the correct | ||
1437 | * return code. | ||
1438 | */ | ||
1439 | *statep = state; | ||
1440 | *whereami = i; | ||
1441 | |||
1442 | return (state & PNG_FP_SAW_DIGIT) != 0; | ||
1443 | } | ||
1444 | |||
1445 | |||
1446 | /* The same but for a complete string. */ | ||
1447 | int | ||
1448 | png_check_fp_string(png_const_charp string, png_size_t size) | ||
1449 | { | ||
1450 | int state=0; | ||
1451 | png_size_t char_index=0; | ||
1452 | |||
1453 | if (png_check_fp_number(string, size, &state, &char_index) && | ||
1454 | (char_index == size || string[char_index] == 0)) | ||
1455 | return state /* must be non-zero - see above */; | ||
1456 | |||
1457 | return 0; /* i.e. fail */ | ||
1458 | } | ||
1459 | #endif /* pCAL or sCAL */ | ||
1460 | |||
1461 | #ifdef PNG_READ_sCAL_SUPPORTED | ||
1462 | # ifdef PNG_FLOATING_POINT_SUPPORTED | ||
1463 | /* Utility used below - a simple accurate power of ten from an integral | ||
1464 | * exponent. | ||
1465 | */ | ||
1466 | static double | ||
1467 | png_pow10(int power) | ||
1468 | { | ||
1469 | int recip = 0; | ||
1470 | double d = 1; | ||
1471 | |||
1472 | /* Handle negative exponent with a reciprocal at the end because | ||
1473 | * 10 is exact whereas .1 is inexact in base 2 | ||
1474 | */ | ||
1475 | if (power < 0) | ||
1476 | { | ||
1477 | if (power < DBL_MIN_10_EXP) return 0; | ||
1478 | recip = 1, power = -power; | ||
1479 | } | ||
1480 | |||
1481 | if (power > 0) | ||
1482 | { | ||
1483 | /* Decompose power bitwise. */ | ||
1484 | double mult = 10; | ||
1485 | do | ||
1486 | { | ||
1487 | if (power & 1) d *= mult; | ||
1488 | mult *= mult; | ||
1489 | power >>= 1; | ||
1490 | } | ||
1491 | while (power > 0); | ||
1492 | |||
1493 | if (recip) d = 1/d; | ||
1494 | } | ||
1495 | /* else power is 0 and d is 1 */ | ||
1496 | |||
1497 | return d; | ||
1498 | } | ||
1499 | |||
1500 | /* Function to format a floating point value in ASCII with a given | ||
1501 | * precision. | ||
1502 | */ | ||
1503 | void /* PRIVATE */ | ||
1504 | png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size, | ||
1505 | double fp, unsigned int precision) | ||
1506 | { | ||
1507 | /* We use standard functions from math.h, but not printf because | ||
1508 | * that would require stdio. The caller must supply a buffer of | ||
1509 | * sufficient size or we will png_error. The tests on size and | ||
1510 | * the space in ascii[] consumed are indicated below. | ||
1511 | */ | ||
1512 | if (precision < 1) | ||
1513 | precision = DBL_DIG; | ||
1514 | |||
1515 | /* Enforce the limit of the implementation precision too. */ | ||
1516 | if (precision > DBL_DIG+1) | ||
1517 | precision = DBL_DIG+1; | ||
1518 | |||
1519 | /* Basic sanity checks */ | ||
1520 | if (size >= precision+5) /* See the requirements below. */ | ||
1521 | { | ||
1522 | if (fp < 0) | ||
1523 | { | ||
1524 | fp = -fp; | ||
1525 | *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */ | ||
1526 | --size; | ||
1527 | } | ||
1528 | |||
1529 | if (fp >= DBL_MIN && fp <= DBL_MAX) | ||
1530 | { | ||
1531 | int exp_b10; /* A base 10 exponent */ | ||
1532 | double base; /* 10^exp_b10 */ | ||
1533 | |||
1534 | /* First extract a base 10 exponent of the number, | ||
1535 | * the calculation below rounds down when converting | ||
1536 | * from base 2 to base 10 (multiply by log10(2) - | ||
1537 | * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to | ||
1538 | * be increased. Note that the arithmetic shift | ||
1539 | * performs a floor() unlike C arithmetic - using a | ||
1540 | * C multiply would break the following for negative | ||
1541 | * exponents. | ||
1542 | */ | ||
1543 | (void)frexp(fp, &exp_b10); /* exponent to base 2 */ | ||
1544 | |||
1545 | exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */ | ||
1546 | |||
1547 | /* Avoid underflow here. */ | ||
1548 | base = png_pow10(exp_b10); /* May underflow */ | ||
1549 | |||
1550 | while (base < DBL_MIN || base < fp) | ||
1551 | { | ||
1552 | /* And this may overflow. */ | ||
1553 | double test = png_pow10(exp_b10+1); | ||
1554 | |||
1555 | if (test <= DBL_MAX) | ||
1556 | ++exp_b10, base = test; | ||
1557 | |||
1558 | else | ||
1559 | break; | ||
1560 | } | ||
1561 | |||
1562 | /* Normalize fp and correct exp_b10, after this fp is in the | ||
1563 | * range [.1,1) and exp_b10 is both the exponent and the digit | ||
1564 | * *before* which the decimal point should be inserted | ||
1565 | * (starting with 0 for the first digit). Note that this | ||
1566 | * works even if 10^exp_b10 is out of range because of the | ||
1567 | * test on DBL_MAX above. | ||
1568 | */ | ||
1569 | fp /= base; | ||
1570 | while (fp >= 1) fp /= 10, ++exp_b10; | ||
1571 | |||
1572 | /* Because of the code above fp may, at this point, be | ||
1573 | * less than .1, this is ok because the code below can | ||
1574 | * handle the leading zeros this generates, so no attempt | ||
1575 | * is made to correct that here. | ||
1576 | */ | ||
1577 | |||
1578 | { | ||
1579 | int czero, clead, cdigits; | ||
1580 | char exponent[10]; | ||
1581 | |||
1582 | /* Allow up to two leading zeros - this will not lengthen | ||
1583 | * the number compared to using E-n. | ||
1584 | */ | ||
1585 | if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */ | ||
1586 | { | ||
1587 | czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */ | ||
1588 | exp_b10 = 0; /* Dot added below before first output. */ | ||
1589 | } | ||
1590 | else | ||
1591 | czero = 0; /* No zeros to add */ | ||
1592 | |||
1593 | /* Generate the digit list, stripping trailing zeros and | ||
1594 | * inserting a '.' before a digit if the exponent is 0. | ||
1595 | */ | ||
1596 | clead = czero; /* Count of leading zeros */ | ||
1597 | cdigits = 0; /* Count of digits in list. */ | ||
1598 | |||
1599 | do | ||
1600 | { | ||
1601 | double d; | ||
1602 | |||
1603 | fp *= 10; | ||
1604 | /* Use modf here, not floor and subtract, so that | ||
1605 | * the separation is done in one step. At the end | ||
1606 | * of the loop don't break the number into parts so | ||
1607 | * that the final digit is rounded. | ||
1608 | */ | ||
1609 | if (cdigits+czero-clead+1 < (int)precision) | ||
1610 | fp = modf(fp, &d); | ||
1611 | |||
1612 | else | ||
1613 | { | ||
1614 | d = floor(fp + .5); | ||
1615 | |||
1616 | if (d > 9) | ||
1617 | { | ||
1618 | /* Rounding up to 10, handle that here. */ | ||
1619 | if (czero > 0) | ||
1620 | { | ||
1621 | --czero, d = 1; | ||
1622 | if (cdigits == 0) --clead; | ||
1623 | } | ||
1624 | else | ||
1625 | { | ||
1626 | while (cdigits > 0 && d > 9) | ||
1627 | { | ||
1628 | int ch = *--ascii; | ||
1629 | |||
1630 | if (exp_b10 != (-1)) | ||
1631 | ++exp_b10; | ||
1632 | |||
1633 | else if (ch == 46) | ||
1634 | { | ||
1635 | ch = *--ascii, ++size; | ||
1636 | /* Advance exp_b10 to '1', so that the | ||
1637 | * decimal point happens after the | ||
1638 | * previous digit. | ||
1639 | */ | ||
1640 | exp_b10 = 1; | ||
1641 | } | ||
1642 | |||
1643 | --cdigits; | ||
1644 | d = ch - 47; /* I.e. 1+(ch-48) */ | ||
1645 | } | ||
1646 | |||
1647 | /* Did we reach the beginning? If so adjust the | ||
1648 | * exponent but take into account the leading | ||
1649 | * decimal point. | ||
1650 | */ | ||
1651 | if (d > 9) /* cdigits == 0 */ | ||
1652 | { | ||
1653 | if (exp_b10 == (-1)) | ||
1654 | { | ||
1655 | /* Leading decimal point (plus zeros?), if | ||
1656 | * we lose the decimal point here it must | ||
1657 | * be reentered below. | ||
1658 | */ | ||
1659 | int ch = *--ascii; | ||
1660 | |||
1661 | if (ch == 46) | ||
1662 | ++size, exp_b10 = 1; | ||
1663 | |||
1664 | /* Else lost a leading zero, so 'exp_b10' is | ||
1665 | * still ok at (-1) | ||
1666 | */ | ||
1667 | } | ||
1668 | else | ||
1669 | ++exp_b10; | ||
1670 | |||
1671 | /* In all cases we output a '1' */ | ||
1672 | d = 1; | ||
1673 | } | ||
1674 | } | ||
1675 | } | ||
1676 | fp = 0; /* Guarantees termination below. */ | ||
1677 | } | ||
1678 | |||
1679 | if (d == 0) | ||
1680 | { | ||
1681 | ++czero; | ||
1682 | if (cdigits == 0) ++clead; | ||
1683 | } | ||
1684 | else | ||
1685 | { | ||
1686 | /* Included embedded zeros in the digit count. */ | ||
1687 | cdigits += czero - clead; | ||
1688 | clead = 0; | ||
1689 | |||
1690 | while (czero > 0) | ||
1691 | { | ||
1692 | /* exp_b10 == (-1) means we just output the decimal | ||
1693 | * place - after the DP don't adjust 'exp_b10' any | ||
1694 | * more! | ||
1695 | */ | ||
1696 | if (exp_b10 != (-1)) | ||
1697 | { | ||
1698 | if (exp_b10 == 0) *ascii++ = 46, --size; | ||
1699 | /* PLUS 1: TOTAL 4 */ | ||
1700 | --exp_b10; | ||
1701 | } | ||
1702 | *ascii++ = 48, --czero; | ||
1703 | } | ||
1704 | |||
1705 | if (exp_b10 != (-1)) | ||
1706 | { | ||
1707 | if (exp_b10 == 0) *ascii++ = 46, --size; /* counted | ||
1708 | above */ | ||
1709 | --exp_b10; | ||
1710 | } | ||
1711 | *ascii++ = (char)(48 + (int)d), ++cdigits; | ||
1712 | } | ||
1713 | } | ||
1714 | while (cdigits+czero-clead < (int)precision && fp > DBL_MIN); | ||
1715 | |||
1716 | /* The total output count (max) is now 4+precision */ | ||
1717 | |||
1718 | /* Check for an exponent, if we don't need one we are | ||
1719 | * done and just need to terminate the string. At | ||
1720 | * this point exp_b10==(-1) is effectively if flag - it got | ||
1721 | * to '-1' because of the decrement after outputing | ||
1722 | * the decimal point above (the exponent required is | ||
1723 | * *not* -1!) | ||
1724 | */ | ||
1725 | if (exp_b10 >= (-1) && exp_b10 <= 2) | ||
1726 | { | ||
1727 | /* The following only happens if we didn't output the | ||
1728 | * leading zeros above for negative exponent, so this | ||
1729 | * doest add to the digit requirement. Note that the | ||
1730 | * two zeros here can only be output if the two leading | ||
1731 | * zeros were *not* output, so this doesn't increase | ||
1732 | * the output count. | ||
1733 | */ | ||
1734 | while (--exp_b10 >= 0) *ascii++ = 48; | ||
1735 | |||
1736 | *ascii = 0; | ||
1737 | |||
1738 | /* Total buffer requirement (including the '\0') is | ||
1739 | * 5+precision - see check at the start. | ||
1740 | */ | ||
1741 | return; | ||
1742 | } | ||
1743 | |||
1744 | /* Here if an exponent is required, adjust size for | ||
1745 | * the digits we output but did not count. The total | ||
1746 | * digit output here so far is at most 1+precision - no | ||
1747 | * decimal point and no leading or trailing zeros have | ||
1748 | * been output. | ||
1749 | */ | ||
1750 | size -= cdigits; | ||
1751 | |||
1752 | *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */ | ||
1753 | |||
1754 | /* The following use of an unsigned temporary avoids ambiguities in | ||
1755 | * the signed arithmetic on exp_b10 and permits GCC at least to do | ||
1756 | * better optimization. | ||
1757 | */ | ||
1758 | { | ||
1759 | unsigned int uexp_b10; | ||
1760 | |||
1761 | if (exp_b10 < 0) | ||
1762 | { | ||
1763 | *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */ | ||
1764 | uexp_b10 = -exp_b10; | ||
1765 | } | ||
1766 | |||
1767 | else | ||
1768 | uexp_b10 = exp_b10; | ||
1769 | |||
1770 | cdigits = 0; | ||
1771 | |||
1772 | while (uexp_b10 > 0) | ||
1773 | { | ||
1774 | exponent[cdigits++] = (char)(48 + uexp_b10 % 10); | ||
1775 | uexp_b10 /= 10; | ||
1776 | } | ||
1777 | } | ||
1778 | |||
1779 | /* Need another size check here for the exponent digits, so | ||
1780 | * this need not be considered above. | ||
1781 | */ | ||
1782 | if ((int)size > cdigits) | ||
1783 | { | ||
1784 | while (cdigits > 0) *ascii++ = exponent[--cdigits]; | ||
1785 | |||
1786 | *ascii = 0; | ||
1787 | |||
1788 | return; | ||
1789 | } | ||
1790 | } | ||
1791 | } | ||
1792 | else if (!(fp >= DBL_MIN)) | ||
1793 | { | ||
1794 | *ascii++ = 48; /* '0' */ | ||
1795 | *ascii = 0; | ||
1796 | return; | ||
1797 | } | ||
1798 | else | ||
1799 | { | ||
1800 | *ascii++ = 105; /* 'i' */ | ||
1801 | *ascii++ = 110; /* 'n' */ | ||
1802 | *ascii++ = 102; /* 'f' */ | ||
1803 | *ascii = 0; | ||
1804 | return; | ||
1805 | } | ||
1806 | } | ||
1807 | |||
1808 | /* Here on buffer too small. */ | ||
1809 | png_error(png_ptr, "ASCII conversion buffer too small"); | ||
1810 | } | ||
1811 | |||
1812 | # endif /* FLOATING_POINT */ | ||
1813 | |||
1814 | # ifdef PNG_FIXED_POINT_SUPPORTED | ||
1815 | /* Function to format a fixed point value in ASCII. | ||
1816 | */ | ||
1817 | void /* PRIVATE */ | ||
1818 | png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size, | ||
1819 | png_fixed_point fp) | ||
1820 | { | ||
1821 | /* Require space for 10 decimal digits, a decimal point, a minus sign and a | ||
1822 | * trailing \0, 13 characters: | ||
1823 | */ | ||
1824 | if (size > 12) | ||
1825 | { | ||
1826 | png_uint_32 num; | ||
1827 | |||
1828 | /* Avoid overflow here on the minimum integer. */ | ||
1829 | if (fp < 0) | ||
1830 | *ascii++ = 45, --size, num = -fp; | ||
1831 | else | ||
1832 | num = fp; | ||
1833 | |||
1834 | if (num <= 0x80000000) /* else overflowed */ | ||
1835 | { | ||
1836 | unsigned int ndigits = 0, first = 16 /* flag value */; | ||
1837 | char digits[10]; | ||
1838 | |||
1839 | while (num) | ||
1840 | { | ||
1841 | /* Split the low digit off num: */ | ||
1842 | unsigned int tmp = num/10; | ||
1843 | num -= tmp*10; | ||
1844 | digits[ndigits++] = (char)(48 + num); | ||
1845 | /* Record the first non-zero digit, note that this is a number | ||
1846 | * starting at 1, it's not actually the array index. | ||
1847 | */ | ||
1848 | if (first == 16 && num > 0) | ||
1849 | first = ndigits; | ||
1850 | num = tmp; | ||
1851 | } | ||
1852 | |||
1853 | if (ndigits > 0) | ||
1854 | { | ||
1855 | while (ndigits > 5) *ascii++ = digits[--ndigits]; | ||
1856 | /* The remaining digits are fractional digits, ndigits is '5' or | ||
1857 | * smaller at this point. It is certainly not zero. Check for a | ||
1858 | * non-zero fractional digit: | ||
1859 | */ | ||
1860 | if (first <= 5) | ||
1861 | { | ||
1862 | unsigned int i; | ||
1863 | *ascii++ = 46; /* decimal point */ | ||
1864 | /* ndigits may be <5 for small numbers, output leading zeros | ||
1865 | * then ndigits digits to first: | ||
1866 | */ | ||
1867 | i = 5; | ||
1868 | while (ndigits < i) *ascii++ = 48, --i; | ||
1869 | while (ndigits >= first) *ascii++ = digits[--ndigits]; | ||
1870 | /* Don't output the trailing zeros! */ | ||
1871 | } | ||
1872 | } | ||
1873 | else | ||
1874 | *ascii++ = 48; | ||
1875 | |||
1876 | /* And null terminate the string: */ | ||
1877 | *ascii = 0; | ||
1878 | return; | ||
1879 | } | ||
1880 | } | ||
1881 | |||
1882 | /* Here on buffer too small. */ | ||
1883 | png_error(png_ptr, "ASCII conversion buffer too small"); | ||
1884 | } | ||
1885 | # endif /* FIXED_POINT */ | ||
1886 | #endif /* READ_SCAL */ | ||
1887 | |||
1888 | #if defined(PNG_FLOATING_POINT_SUPPORTED) && \ | ||
1889 | !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) | ||
1890 | png_fixed_point | ||
1891 | png_fixed(png_structp png_ptr, double fp, png_const_charp text) | ||
1892 | { | ||
1893 | double r = floor(100000 * fp + .5); | ||
1894 | |||
1895 | if (r > 2147483647. || r < -2147483648.) | ||
1896 | png_fixed_error(png_ptr, text); | ||
1897 | |||
1898 | return (png_fixed_point)r; | ||
1899 | } | ||
1900 | #endif | ||
1901 | |||
1902 | #if defined(PNG_READ_GAMMA_SUPPORTED) || \ | ||
1903 | defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG__READ_pHYs_SUPPORTED) | ||
1904 | /* muldiv functions */ | ||
1905 | /* This API takes signed arguments and rounds the result to the nearest | ||
1906 | * integer (or, for a fixed point number - the standard argument - to | ||
1907 | * the nearest .00001). Overflow and divide by zero are signalled in | ||
1908 | * the result, a boolean - true on success, false on overflow. | ||
1909 | */ | ||
1910 | int | ||
1911 | png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, | ||
1912 | png_int_32 divisor) | ||
1913 | { | ||
1914 | /* Return a * times / divisor, rounded. */ | ||
1915 | if (divisor != 0) | ||
1916 | { | ||
1917 | if (a == 0 || times == 0) | ||
1918 | { | ||
1919 | *res = 0; | ||
1920 | return 1; | ||
1921 | } | ||
1922 | else | ||
1923 | { | ||
1924 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
1925 | double r = a; | ||
1926 | r *= times; | ||
1927 | r /= divisor; | ||
1928 | r = floor(r+.5); | ||
1929 | |||
1930 | /* A png_fixed_point is a 32-bit integer. */ | ||
1931 | if (r <= 2147483647. && r >= -2147483648.) | ||
1932 | { | ||
1933 | *res = (png_fixed_point)r; | ||
1934 | return 1; | ||
1935 | } | ||
1936 | #else | ||
1937 | int negative = 0; | ||
1938 | png_uint_32 A, T, D; | ||
1939 | png_uint_32 s16, s32, s00; | ||
1940 | |||
1941 | if (a < 0) | ||
1942 | negative = 1, A = -a; | ||
1943 | else | ||
1944 | A = a; | ||
1945 | |||
1946 | if (times < 0) | ||
1947 | negative = !negative, T = -times; | ||
1948 | else | ||
1949 | T = times; | ||
1950 | |||
1951 | if (divisor < 0) | ||
1952 | negative = !negative, D = -divisor; | ||
1953 | else | ||
1954 | D = divisor; | ||
1955 | |||
1956 | /* Following can't overflow because the arguments only | ||
1957 | * have 31 bits each, however the result may be 32 bits. | ||
1958 | */ | ||
1959 | s16 = (A >> 16) * (T & 0xffff) + | ||
1960 | (A & 0xffff) * (T >> 16); | ||
1961 | /* Can't overflow because the a*times bit is only 30 | ||
1962 | * bits at most. | ||
1963 | */ | ||
1964 | s32 = (A >> 16) * (T >> 16) + (s16 >> 16); | ||
1965 | s00 = (A & 0xffff) * (T & 0xffff); | ||
1966 | |||
1967 | s16 = (s16 & 0xffff) << 16; | ||
1968 | s00 += s16; | ||
1969 | |||
1970 | if (s00 < s16) | ||
1971 | ++s32; /* carry */ | ||
1972 | |||
1973 | if (s32 < D) /* else overflow */ | ||
1974 | { | ||
1975 | /* s32.s00 is now the 64-bit product, do a standard | ||
1976 | * division, we know that s32 < D, so the maximum | ||
1977 | * required shift is 31. | ||
1978 | */ | ||
1979 | int bitshift = 32; | ||
1980 | png_fixed_point result = 0; /* NOTE: signed */ | ||
1981 | |||
1982 | while (--bitshift >= 0) | ||
1983 | { | ||
1984 | png_uint_32 d32, d00; | ||
1985 | |||
1986 | if (bitshift > 0) | ||
1987 | d32 = D >> (32-bitshift), d00 = D << bitshift; | ||
1988 | |||
1989 | else | ||
1990 | d32 = 0, d00 = D; | ||
1991 | |||
1992 | if (s32 > d32) | ||
1993 | { | ||
1994 | if (s00 < d00) --s32; /* carry */ | ||
1995 | s32 -= d32, s00 -= d00, result += 1<<bitshift; | ||
1996 | } | ||
1997 | |||
1998 | else | ||
1999 | if (s32 == d32 && s00 >= d00) | ||
2000 | s32 = 0, s00 -= d00, result += 1<<bitshift; | ||
2001 | } | ||
2002 | |||
2003 | /* Handle the rounding. */ | ||
2004 | if (s00 >= (D >> 1)) | ||
2005 | ++result; | ||
2006 | |||
2007 | if (negative) | ||
2008 | result = -result; | ||
2009 | |||
2010 | /* Check for overflow. */ | ||
2011 | if ((negative && result <= 0) || (!negative && result >= 0)) | ||
2012 | { | ||
2013 | *res = result; | ||
2014 | return 1; | ||
2015 | } | ||
2016 | } | ||
2017 | #endif | ||
2018 | } | ||
2019 | } | ||
2020 | |||
2021 | return 0; | ||
2022 | } | ||
2023 | #endif /* READ_GAMMA || INCH_CONVERSIONS */ | ||
2024 | |||
2025 | #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED) | ||
2026 | /* The following is for when the caller doesn't much care about the | ||
2027 | * result. | ||
2028 | */ | ||
2029 | png_fixed_point | ||
2030 | png_muldiv_warn(png_structp png_ptr, png_fixed_point a, png_int_32 times, | ||
2031 | png_int_32 divisor) | ||
2032 | { | ||
2033 | png_fixed_point result; | ||
2034 | |||
2035 | if (png_muldiv(&result, a, times, divisor)) | ||
2036 | return result; | ||
2037 | |||
2038 | png_warning(png_ptr, "fixed point overflow ignored"); | ||
2039 | return 0; | ||
2040 | } | ||
2041 | #endif | ||
2042 | |||
2043 | #ifdef PNG_READ_GAMMA_SUPPORTED /* more fixed point functions for gammma */ | ||
2044 | /* Calculate a reciprocal, return 0 on div-by-zero or overflow. */ | ||
2045 | png_fixed_point | ||
2046 | png_reciprocal(png_fixed_point a) | ||
2047 | { | ||
2048 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
2049 | double r = floor(1E10/a+.5); | ||
2050 | |||
2051 | if (r <= 2147483647. && r >= -2147483648.) | ||
2052 | return (png_fixed_point)r; | ||
2053 | #else | ||
2054 | png_fixed_point res; | ||
2055 | |||
2056 | if (png_muldiv(&res, 100000, 100000, a)) | ||
2057 | return res; | ||
2058 | #endif | ||
2059 | |||
2060 | return 0; /* error/overflow */ | ||
2061 | } | ||
2062 | |||
2063 | /* A local convenience routine. */ | ||
2064 | static png_fixed_point | ||
2065 | png_product2(png_fixed_point a, png_fixed_point b) | ||
2066 | { | ||
2067 | /* The required result is 1/a * 1/b; the following preserves accuracy. */ | ||
2068 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
2069 | double r = a * 1E-5; | ||
2070 | r *= b; | ||
2071 | r = floor(r+.5); | ||
2072 | |||
2073 | if (r <= 2147483647. && r >= -2147483648.) | ||
2074 | return (png_fixed_point)r; | ||
2075 | #else | ||
2076 | png_fixed_point res; | ||
2077 | |||
2078 | if (png_muldiv(&res, a, b, 100000)) | ||
2079 | return res; | ||
2080 | #endif | ||
2081 | |||
2082 | return 0; /* overflow */ | ||
2083 | } | ||
2084 | |||
2085 | /* The inverse of the above. */ | ||
2086 | png_fixed_point | ||
2087 | png_reciprocal2(png_fixed_point a, png_fixed_point b) | ||
2088 | { | ||
2089 | /* The required result is 1/a * 1/b; the following preserves accuracy. */ | ||
2090 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
2091 | double r = 1E15/a; | ||
2092 | r /= b; | ||
2093 | r = floor(r+.5); | ||
2094 | |||
2095 | if (r <= 2147483647. && r >= -2147483648.) | ||
2096 | return (png_fixed_point)r; | ||
2097 | #else | ||
2098 | /* This may overflow because the range of png_fixed_point isn't symmetric, | ||
2099 | * but this API is only used for the product of file and screen gamma so it | ||
2100 | * doesn't matter that the smallest number it can produce is 1/21474, not | ||
2101 | * 1/100000 | ||
2102 | */ | ||
2103 | png_fixed_point res = png_product2(a, b); | ||
2104 | |||
2105 | if (res != 0) | ||
2106 | return png_reciprocal(res); | ||
2107 | #endif | ||
2108 | |||
2109 | return 0; /* overflow */ | ||
2110 | } | ||
2111 | #endif /* READ_GAMMA */ | ||
2112 | |||
2113 | #ifdef PNG_CHECK_cHRM_SUPPORTED | ||
2114 | /* Added at libpng version 1.2.34 (Dec 8, 2008) and 1.4.0 (Jan 2, | ||
2115 | * 2010: moved from pngset.c) */ | ||
2116 | /* | ||
2117 | * Multiply two 32-bit numbers, V1 and V2, using 32-bit | ||
2118 | * arithmetic, to produce a 64-bit result in the HI/LO words. | ||
2119 | * | ||
2120 | * A B | ||
2121 | * x C D | ||
2122 | * ------ | ||
2123 | * AD || BD | ||
2124 | * AC || CB || 0 | ||
2125 | * | ||
2126 | * where A and B are the high and low 16-bit words of V1, | ||
2127 | * C and D are the 16-bit words of V2, AD is the product of | ||
2128 | * A and D, and X || Y is (X << 16) + Y. | ||
2129 | */ | ||
2130 | |||
2131 | void /* PRIVATE */ | ||
2132 | png_64bit_product (long v1, long v2, unsigned long *hi_product, | ||
2133 | unsigned long *lo_product) | ||
2134 | { | ||
2135 | int a, b, c, d; | ||
2136 | long lo, hi, x, y; | ||
2137 | |||
2138 | a = (v1 >> 16) & 0xffff; | ||
2139 | b = v1 & 0xffff; | ||
2140 | c = (v2 >> 16) & 0xffff; | ||
2141 | d = v2 & 0xffff; | ||
2142 | |||
2143 | lo = b * d; /* BD */ | ||
2144 | x = a * d + c * b; /* AD + CB */ | ||
2145 | y = ((lo >> 16) & 0xffff) + x; | ||
2146 | |||
2147 | lo = (lo & 0xffff) | ((y & 0xffff) << 16); | ||
2148 | hi = (y >> 16) & 0xffff; | ||
2149 | |||
2150 | hi += a * c; /* AC */ | ||
2151 | |||
2152 | *hi_product = (unsigned long)hi; | ||
2153 | *lo_product = (unsigned long)lo; | ||
2154 | } | ||
2155 | #endif /* CHECK_cHRM */ | ||
2156 | |||
2157 | #ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */ | ||
2158 | #ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
2159 | /* Fixed point gamma. | ||
2160 | * | ||
2161 | * To calculate gamma this code implements fast log() and exp() calls using only | ||
2162 | * fixed point arithmetic. This code has sufficient precision for either 8-bit | ||
2163 | * or 16-bit sample values. | ||
2164 | * | ||
2165 | * The tables used here were calculated using simple 'bc' programs, but C double | ||
2166 | * precision floating point arithmetic would work fine. The programs are given | ||
2167 | * at the head of each table. | ||
2168 | * | ||
2169 | * 8-bit log table | ||
2170 | * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to | ||
2171 | * 255, so it's the base 2 logarithm of a normalized 8-bit floating point | ||
2172 | * mantissa. The numbers are 32-bit fractions. | ||
2173 | */ | ||
2174 | static png_uint_32 | ||
2175 | png_8bit_l2[128] = | ||
2176 | { | ||
2177 | # ifdef PNG_DO_BC | ||
2178 | for (i=128;i<256;++i) { .5 - l(i/255)/l(2)*65536*65536; } | ||
2179 | # else | ||
2180 | 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U, | ||
2181 | 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U, | ||
2182 | 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U, | ||
2183 | 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U, | ||
2184 | 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U, | ||
2185 | 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U, | ||
2186 | 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U, | ||
2187 | 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U, | ||
2188 | 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U, | ||
2189 | 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U, | ||
2190 | 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U, | ||
2191 | 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U, | ||
2192 | 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U, | ||
2193 | 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U, | ||
2194 | 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U, | ||
2195 | 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U, | ||
2196 | 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U, | ||
2197 | 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U, | ||
2198 | 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U, | ||
2199 | 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U, | ||
2200 | 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U, | ||
2201 | 24347096U, 0U | ||
2202 | # endif | ||
2203 | |||
2204 | #if 0 | ||
2205 | /* The following are the values for 16-bit tables - these work fine for the | ||
2206 | * 8-bit conversions but produce very slightly larger errors in the 16-bit | ||
2207 | * log (about 1.2 as opposed to 0.7 absolute error in the final value). To | ||
2208 | * use these all the shifts below must be adjusted appropriately. | ||
2209 | */ | ||
2210 | 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054, | ||
2211 | 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803, | ||
2212 | 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068, | ||
2213 | 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782, | ||
2214 | 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887, | ||
2215 | 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339, | ||
2216 | 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098, | ||
2217 | 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132, | ||
2218 | 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415, | ||
2219 | 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523, | ||
2220 | 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495, | ||
2221 | 1119, 744, 372 | ||
2222 | #endif | ||
2223 | }; | ||
2224 | |||
2225 | PNG_STATIC png_int_32 | ||
2226 | png_log8bit(unsigned int x) | ||
2227 | { | ||
2228 | unsigned int lg2 = 0; | ||
2229 | /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log, | ||
2230 | * because the log is actually negate that means adding 1. The final | ||
2231 | * returned value thus has the range 0 (for 255 input) to 7.994 (for 1 | ||
2232 | * input), return 7.99998 for the overflow (log 0) case - so the result is | ||
2233 | * always at most 19 bits. | ||
2234 | */ | ||
2235 | if ((x &= 0xff) == 0) | ||
2236 | return 0xffffffff; | ||
2237 | |||
2238 | if ((x & 0xf0) == 0) | ||
2239 | lg2 = 4, x <<= 4; | ||
2240 | |||
2241 | if ((x & 0xc0) == 0) | ||
2242 | lg2 += 2, x <<= 2; | ||
2243 | |||
2244 | if ((x & 0x80) == 0) | ||
2245 | lg2 += 1, x <<= 1; | ||
2246 | |||
2247 | /* result is at most 19 bits, so this cast is safe: */ | ||
2248 | return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16)); | ||
2249 | } | ||
2250 | |||
2251 | /* The above gives exact (to 16 binary places) log2 values for 8-bit images, | ||
2252 | * for 16-bit images we use the most significant 8 bits of the 16-bit value to | ||
2253 | * get an approximation then multiply the approximation by a correction factor | ||
2254 | * determined by the remaining up to 8 bits. This requires an additional step | ||
2255 | * in the 16-bit case. | ||
2256 | * | ||
2257 | * We want log2(value/65535), we have log2(v'/255), where: | ||
2258 | * | ||
2259 | * value = v' * 256 + v'' | ||
2260 | * = v' * f | ||
2261 | * | ||
2262 | * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128 | ||
2263 | * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less | ||
2264 | * than 258. The final factor also needs to correct for the fact that our 8-bit | ||
2265 | * value is scaled by 255, whereas the 16-bit values must be scaled by 65535. | ||
2266 | * | ||
2267 | * This gives a final formula using a calculated value 'x' which is value/v' and | ||
2268 | * scaling by 65536 to match the above table: | ||
2269 | * | ||
2270 | * log2(x/257) * 65536 | ||
2271 | * | ||
2272 | * Since these numbers are so close to '1' we can use simple linear | ||
2273 | * interpolation between the two end values 256/257 (result -368.61) and 258/257 | ||
2274 | * (result 367.179). The values used below are scaled by a further 64 to give | ||
2275 | * 16-bit precision in the interpolation: | ||
2276 | * | ||
2277 | * Start (256): -23591 | ||
2278 | * Zero (257): 0 | ||
2279 | * End (258): 23499 | ||
2280 | */ | ||
2281 | PNG_STATIC png_int_32 | ||
2282 | png_log16bit(png_uint_32 x) | ||
2283 | { | ||
2284 | unsigned int lg2 = 0; | ||
2285 | |||
2286 | /* As above, but now the input has 16 bits. */ | ||
2287 | if ((x &= 0xffff) == 0) | ||
2288 | return 0xffffffff; | ||
2289 | |||
2290 | if ((x & 0xff00) == 0) | ||
2291 | lg2 = 8, x <<= 8; | ||
2292 | |||
2293 | if ((x & 0xf000) == 0) | ||
2294 | lg2 += 4, x <<= 4; | ||
2295 | |||
2296 | if ((x & 0xc000) == 0) | ||
2297 | lg2 += 2, x <<= 2; | ||
2298 | |||
2299 | if ((x & 0x8000) == 0) | ||
2300 | lg2 += 1, x <<= 1; | ||
2301 | |||
2302 | /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional | ||
2303 | * value. | ||
2304 | */ | ||
2305 | lg2 <<= 28; | ||
2306 | lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4; | ||
2307 | |||
2308 | /* Now we need to interpolate the factor, this requires a division by the top | ||
2309 | * 8 bits. Do this with maximum precision. | ||
2310 | */ | ||
2311 | x = ((x << 16) + (x >> 9)) / (x >> 8); | ||
2312 | |||
2313 | /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24, | ||
2314 | * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly | ||
2315 | * 16 bits to interpolate to get the low bits of the result. Round the | ||
2316 | * answer. Note that the end point values are scaled by 64 to retain overall | ||
2317 | * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust | ||
2318 | * the overall scaling by 6-12. Round at every step. | ||
2319 | */ | ||
2320 | x -= 1U << 24; | ||
2321 | |||
2322 | if (x <= 65536U) /* <= '257' */ | ||
2323 | lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12); | ||
2324 | |||
2325 | else | ||
2326 | lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12); | ||
2327 | |||
2328 | /* Safe, because the result can't have more than 20 bits: */ | ||
2329 | return (png_int_32)((lg2 + 2048) >> 12); | ||
2330 | } | ||
2331 | |||
2332 | /* The 'exp()' case must invert the above, taking a 20-bit fixed point | ||
2333 | * logarithmic value and returning a 16 or 8-bit number as appropriate. In | ||
2334 | * each case only the low 16 bits are relevant - the fraction - since the | ||
2335 | * integer bits (the top 4) simply determine a shift. | ||
2336 | * | ||
2337 | * The worst case is the 16-bit distinction between 65535 and 65534, this | ||
2338 | * requires perhaps spurious accuracy in the decoding of the logarithm to | ||
2339 | * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance | ||
2340 | * of getting this accuracy in practice. | ||
2341 | * | ||
2342 | * To deal with this the following exp() function works out the exponent of the | ||
2343 | * frational part of the logarithm by using an accurate 32-bit value from the | ||
2344 | * top four fractional bits then multiplying in the remaining bits. | ||
2345 | */ | ||
2346 | static png_uint_32 | ||
2347 | png_32bit_exp[16] = | ||
2348 | { | ||
2349 | # ifdef PNG_DO_BC | ||
2350 | for (i=0;i<16;++i) { .5 + e(-i/16*l(2))*2^32; } | ||
2351 | # else | ||
2352 | /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */ | ||
2353 | 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U, | ||
2354 | 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U, | ||
2355 | 2553802834U, 2445529972U, 2341847524U, 2242560872U | ||
2356 | # endif | ||
2357 | }; | ||
2358 | |||
2359 | /* Adjustment table; provided to explain the numbers in the code below. */ | ||
2360 | #ifdef PNG_DO_BC | ||
2361 | for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"} | ||
2362 | 11 44937.64284865548751208448 | ||
2363 | 10 45180.98734845585101160448 | ||
2364 | 9 45303.31936980687359311872 | ||
2365 | 8 45364.65110595323018870784 | ||
2366 | 7 45395.35850361789624614912 | ||
2367 | 6 45410.72259715102037508096 | ||
2368 | 5 45418.40724413220722311168 | ||
2369 | 4 45422.25021786898173001728 | ||
2370 | 3 45424.17186732298419044352 | ||
2371 | 2 45425.13273269940811464704 | ||
2372 | 1 45425.61317555035558641664 | ||
2373 | 0 45425.85339951654943850496 | ||
2374 | #endif | ||
2375 | |||
2376 | PNG_STATIC png_uint_32 | ||
2377 | png_exp(png_fixed_point x) | ||
2378 | { | ||
2379 | if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */ | ||
2380 | { | ||
2381 | /* Obtain a 4-bit approximation */ | ||
2382 | png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf]; | ||
2383 | |||
2384 | /* Incorporate the low 12 bits - these decrease the returned value by | ||
2385 | * multiplying by a number less than 1 if the bit is set. The multiplier | ||
2386 | * is determined by the above table and the shift. Notice that the values | ||
2387 | * converge on 45426 and this is used to allow linear interpolation of the | ||
2388 | * low bits. | ||
2389 | */ | ||
2390 | if (x & 0x800) | ||
2391 | e -= (((e >> 16) * 44938U) + 16U) >> 5; | ||
2392 | |||
2393 | if (x & 0x400) | ||
2394 | e -= (((e >> 16) * 45181U) + 32U) >> 6; | ||
2395 | |||
2396 | if (x & 0x200) | ||
2397 | e -= (((e >> 16) * 45303U) + 64U) >> 7; | ||
2398 | |||
2399 | if (x & 0x100) | ||
2400 | e -= (((e >> 16) * 45365U) + 128U) >> 8; | ||
2401 | |||
2402 | if (x & 0x080) | ||
2403 | e -= (((e >> 16) * 45395U) + 256U) >> 9; | ||
2404 | |||
2405 | if (x & 0x040) | ||
2406 | e -= (((e >> 16) * 45410U) + 512U) >> 10; | ||
2407 | |||
2408 | /* And handle the low 6 bits in a single block. */ | ||
2409 | e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9; | ||
2410 | |||
2411 | /* Handle the upper bits of x. */ | ||
2412 | e >>= x >> 16; | ||
2413 | return e; | ||
2414 | } | ||
2415 | |||
2416 | /* Check for overflow */ | ||
2417 | if (x <= 0) | ||
2418 | return png_32bit_exp[0]; | ||
2419 | |||
2420 | /* Else underflow */ | ||
2421 | return 0; | ||
2422 | } | ||
2423 | |||
2424 | PNG_STATIC png_byte | ||
2425 | png_exp8bit(png_fixed_point lg2) | ||
2426 | { | ||
2427 | /* Get a 32-bit value: */ | ||
2428 | png_uint_32 x = png_exp(lg2); | ||
2429 | |||
2430 | /* Convert the 32-bit value to 0..255 by multiplying by 256-1, note that the | ||
2431 | * second, rounding, step can't overflow because of the first, subtraction, | ||
2432 | * step. | ||
2433 | */ | ||
2434 | x -= x >> 8; | ||
2435 | return (png_byte)((x + 0x7fffffU) >> 24); | ||
2436 | } | ||
2437 | |||
2438 | PNG_STATIC png_uint_16 | ||
2439 | png_exp16bit(png_fixed_point lg2) | ||
2440 | { | ||
2441 | /* Get a 32-bit value: */ | ||
2442 | png_uint_32 x = png_exp(lg2); | ||
2443 | |||
2444 | /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */ | ||
2445 | x -= x >> 16; | ||
2446 | return (png_uint_16)((x + 32767U) >> 16); | ||
2447 | } | ||
2448 | #endif /* FLOATING_ARITHMETIC */ | ||
2449 | |||
2450 | png_byte | ||
2451 | png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val) | ||
2452 | { | ||
2453 | if (value > 0 && value < 255) | ||
2454 | { | ||
2455 | # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
2456 | double r = floor(255*pow(value/255.,gamma_val*.00001)+.5); | ||
2457 | return (png_byte)r; | ||
2458 | # else | ||
2459 | png_int_32 lg2 = png_log8bit(value); | ||
2460 | png_fixed_point res; | ||
2461 | |||
2462 | if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1)) | ||
2463 | return png_exp8bit(res); | ||
2464 | |||
2465 | /* Overflow. */ | ||
2466 | value = 0; | ||
2467 | # endif | ||
2468 | } | ||
2469 | |||
2470 | return (png_byte)value; | ||
2471 | } | ||
2472 | |||
2473 | png_uint_16 | ||
2474 | png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val) | ||
2475 | { | ||
2476 | if (value > 0 && value < 65535) | ||
2477 | { | ||
2478 | # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
2479 | double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5); | ||
2480 | return (png_uint_16)r; | ||
2481 | # else | ||
2482 | png_int_32 lg2 = png_log16bit(value); | ||
2483 | png_fixed_point res; | ||
2484 | |||
2485 | if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1)) | ||
2486 | return png_exp16bit(res); | ||
2487 | |||
2488 | /* Overflow. */ | ||
2489 | value = 0; | ||
2490 | # endif | ||
2491 | } | ||
2492 | |||
2493 | return (png_uint_16)value; | ||
2494 | } | ||
2495 | |||
2496 | /* This does the right thing based on the bit_depth field of the | ||
2497 | * png_struct, interpreting values as 8-bit or 16-bit. While the result | ||
2498 | * is nominally a 16-bit value if bit depth is 8 then the result is | ||
2499 | * 8-bit (as are the arguments.) | ||
2500 | */ | ||
2501 | png_uint_16 /* PRIVATE */ | ||
2502 | png_gamma_correct(png_structp png_ptr, unsigned int value, | ||
2503 | png_fixed_point gamma_val) | ||
2504 | { | ||
2505 | if (png_ptr->bit_depth == 8) | ||
2506 | return png_gamma_8bit_correct(value, gamma_val); | ||
2507 | |||
2508 | else | ||
2509 | return png_gamma_16bit_correct(value, gamma_val); | ||
2510 | } | ||
2511 | |||
2512 | /* This is the shared test on whether a gamma value is 'significant' - whether | ||
2513 | * it is worth doing gamma correction. | ||
2514 | */ | ||
2515 | int /* PRIVATE */ | ||
2516 | png_gamma_significant(png_fixed_point gamma_val) | ||
2517 | { | ||
2518 | return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED || | ||
2519 | gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED; | ||
2520 | } | ||
2521 | |||
2522 | /* Internal function to build a single 16-bit table - the table consists of | ||
2523 | * 'num' 256-entry subtables, where 'num' is determined by 'shift' - the amount | ||
2524 | * to shift the input values right (or 16-number_of_signifiant_bits). | ||
2525 | * | ||
2526 | * The caller is responsible for ensuring that the table gets cleaned up on | ||
2527 | * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument | ||
2528 | * should be somewhere that will be cleaned. | ||
2529 | */ | ||
2530 | static void | ||
2531 | png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable, | ||
2532 | PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) | ||
2533 | { | ||
2534 | /* Various values derived from 'shift': */ | ||
2535 | PNG_CONST unsigned int num = 1U << (8U - shift); | ||
2536 | PNG_CONST unsigned int max = (1U << (16U - shift))-1U; | ||
2537 | PNG_CONST unsigned int max_by_2 = 1U << (15U-shift); | ||
2538 | unsigned int i; | ||
2539 | |||
2540 | png_uint_16pp table = *ptable = | ||
2541 | (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p)); | ||
2542 | |||
2543 | for (i = 0; i < num; i++) | ||
2544 | { | ||
2545 | png_uint_16p sub_table = table[i] = | ||
2546 | (png_uint_16p)png_malloc(png_ptr, 256 * png_sizeof(png_uint_16)); | ||
2547 | |||
2548 | /* The 'threshold' test is repeated here because it can arise for one of | ||
2549 | * the 16-bit tables even if the others don't hit it. | ||
2550 | */ | ||
2551 | if (png_gamma_significant(gamma_val)) | ||
2552 | { | ||
2553 | /* The old code would overflow at the end and this would cause the | ||
2554 | * 'pow' function to return a result >1, resulting in an | ||
2555 | * arithmetic error. This code follows the spec exactly; ig is | ||
2556 | * the recovered input sample, it always has 8-16 bits. | ||
2557 | * | ||
2558 | * We want input * 65535/max, rounded, the arithmetic fits in 32 | ||
2559 | * bits (unsigned) so long as max <= 32767. | ||
2560 | */ | ||
2561 | unsigned int j; | ||
2562 | for (j = 0; j < 256; j++) | ||
2563 | { | ||
2564 | png_uint_32 ig = (j << (8-shift)) + i; | ||
2565 | # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED | ||
2566 | /* Inline the 'max' scaling operation: */ | ||
2567 | double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5); | ||
2568 | sub_table[j] = (png_uint_16)d; | ||
2569 | # else | ||
2570 | if (shift) | ||
2571 | ig = (ig * 65535U + max_by_2)/max; | ||
2572 | |||
2573 | sub_table[j] = png_gamma_16bit_correct(ig, gamma_val); | ||
2574 | # endif | ||
2575 | } | ||
2576 | } | ||
2577 | else | ||
2578 | { | ||
2579 | /* We must still build a table, but do it the fast way. */ | ||
2580 | unsigned int j; | ||
2581 | |||
2582 | for (j = 0; j < 256; j++) | ||
2583 | { | ||
2584 | png_uint_32 ig = (j << (8-shift)) + i; | ||
2585 | |||
2586 | if (shift) | ||
2587 | ig = (ig * 65535U + max_by_2)/max; | ||
2588 | |||
2589 | sub_table[j] = (png_uint_16)ig; | ||
2590 | } | ||
2591 | } | ||
2592 | } | ||
2593 | } | ||
2594 | |||
2595 | /* NOTE: this function expects the *inverse* of the overall gamma transformation | ||
2596 | * required. | ||
2597 | */ | ||
2598 | static void | ||
2599 | png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable, | ||
2600 | PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) | ||
2601 | { | ||
2602 | PNG_CONST unsigned int num = 1U << (8U - shift); | ||
2603 | PNG_CONST unsigned int max = (1U << (16U - shift))-1U; | ||
2604 | unsigned int i; | ||
2605 | png_uint_32 last; | ||
2606 | |||
2607 | png_uint_16pp table = *ptable = | ||
2608 | (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p)); | ||
2609 | |||
2610 | /* 'num' is the number of tables and also the number of low bits of the | ||
2611 | * input 16-bit value used to select a table. Each table is itself indexed | ||
2612 | * by the high 8 bits of the value. | ||
2613 | */ | ||
2614 | for (i = 0; i < num; i++) | ||
2615 | table[i] = (png_uint_16p)png_malloc(png_ptr, | ||
2616 | 256 * png_sizeof(png_uint_16)); | ||
2617 | |||
2618 | /* 'gamma_val' is set to the reciprocal of the value calculated above, so | ||
2619 | * pow(out,g) is an *input* value. 'last' is the last input value set. | ||
2620 | * | ||
2621 | * In the loop 'i' is used to find output values. Since the output is | ||
2622 | * 8-bit there are only 256 possible values. The tables are set up to | ||
2623 | * select the closest possible output value for each input by finding | ||
2624 | * the input value at the boundary between each pair of output values | ||
2625 | * and filling the table up to that boundary with the lower output | ||
2626 | * value. | ||
2627 | * | ||
2628 | * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit | ||
2629 | * values the code below uses a 16-bit value in i; the values start at | ||
2630 | * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last | ||
2631 | * entries are filled with 255). Start i at 128 and fill all 'last' | ||
2632 | * table entries <= 'max' | ||
2633 | */ | ||
2634 | last = 0; | ||
2635 | for (i = 0; i < 255; ++i) /* 8-bit output value */ | ||
2636 | { | ||
2637 | /* Find the corresponding maximum input value */ | ||
2638 | png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */ | ||
2639 | |||
2640 | /* Find the boundary value in 16 bits: */ | ||
2641 | png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val); | ||
2642 | |||
2643 | /* Adjust (round) to (16-shift) bits: */ | ||
2644 | bound = (bound * max + 32768U)/65535U + 1U; | ||
2645 | |||
2646 | while (last < bound) | ||
2647 | { | ||
2648 | table[last & (0xffU >> shift)][last >> (8U - shift)] = out; | ||
2649 | last++; | ||
2650 | } | ||
2651 | } | ||
2652 | |||
2653 | /* And fill in the final entries. */ | ||
2654 | while (last < (num << 8)) | ||
2655 | { | ||
2656 | table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U; | ||
2657 | last++; | ||
2658 | } | ||
2659 | } | ||
2660 | |||
2661 | /* Build a single 8-bit table: same as the 16-bit case but much simpler (and | ||
2662 | * typically much faster). Note that libpng currently does no sBIT processing | ||
2663 | * (apparently contrary to the spec) so a 256-entry table is always generated. | ||
2664 | */ | ||
2665 | static void | ||
2666 | png_build_8bit_table(png_structp png_ptr, png_bytepp ptable, | ||
2667 | PNG_CONST png_fixed_point gamma_val) | ||
2668 | { | ||
2669 | unsigned int i; | ||
2670 | png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256); | ||
2671 | |||
2672 | if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++) | ||
2673 | table[i] = png_gamma_8bit_correct(i, gamma_val); | ||
2674 | |||
2675 | else for (i=0; i<256; ++i) | ||
2676 | table[i] = (png_byte)i; | ||
2677 | } | ||
2678 | |||
2679 | /* Used from png_read_destroy and below to release the memory used by the gamma | ||
2680 | * tables. | ||
2681 | */ | ||
2682 | void /* PRIVATE */ | ||
2683 | png_destroy_gamma_table(png_structp png_ptr) | ||
2684 | { | ||
2685 | png_free(png_ptr, png_ptr->gamma_table); | ||
2686 | png_ptr->gamma_table = NULL; | ||
2687 | |||
2688 | if (png_ptr->gamma_16_table != NULL) | ||
2689 | { | ||
2690 | int i; | ||
2691 | int istop = (1 << (8 - png_ptr->gamma_shift)); | ||
2692 | for (i = 0; i < istop; i++) | ||
2693 | { | ||
2694 | png_free(png_ptr, png_ptr->gamma_16_table[i]); | ||
2695 | } | ||
2696 | png_free(png_ptr, png_ptr->gamma_16_table); | ||
2697 | png_ptr->gamma_16_table = NULL; | ||
2698 | } | ||
2699 | |||
2700 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ | ||
2701 | defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ | ||
2702 | defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) | ||
2703 | png_free(png_ptr, png_ptr->gamma_from_1); | ||
2704 | png_ptr->gamma_from_1 = NULL; | ||
2705 | png_free(png_ptr, png_ptr->gamma_to_1); | ||
2706 | png_ptr->gamma_to_1 = NULL; | ||
2707 | |||
2708 | if (png_ptr->gamma_16_from_1 != NULL) | ||
2709 | { | ||
2710 | int i; | ||
2711 | int istop = (1 << (8 - png_ptr->gamma_shift)); | ||
2712 | for (i = 0; i < istop; i++) | ||
2713 | { | ||
2714 | png_free(png_ptr, png_ptr->gamma_16_from_1[i]); | ||
2715 | } | ||
2716 | png_free(png_ptr, png_ptr->gamma_16_from_1); | ||
2717 | png_ptr->gamma_16_from_1 = NULL; | ||
2718 | } | ||
2719 | if (png_ptr->gamma_16_to_1 != NULL) | ||
2720 | { | ||
2721 | int i; | ||
2722 | int istop = (1 << (8 - png_ptr->gamma_shift)); | ||
2723 | for (i = 0; i < istop; i++) | ||
2724 | { | ||
2725 | png_free(png_ptr, png_ptr->gamma_16_to_1[i]); | ||
2726 | } | ||
2727 | png_free(png_ptr, png_ptr->gamma_16_to_1); | ||
2728 | png_ptr->gamma_16_to_1 = NULL; | ||
2729 | } | ||
2730 | #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ | ||
2731 | } | ||
2732 | |||
2733 | /* We build the 8- or 16-bit gamma tables here. Note that for 16-bit | ||
2734 | * tables, we don't make a full table if we are reducing to 8-bit in | ||
2735 | * the future. Note also how the gamma_16 tables are segmented so that | ||
2736 | * we don't need to allocate > 64K chunks for a full 16-bit table. | ||
2737 | */ | ||
2738 | void /* PRIVATE */ | ||
2739 | png_build_gamma_table(png_structp png_ptr, int bit_depth) | ||
2740 | { | ||
2741 | png_debug(1, "in png_build_gamma_table"); | ||
2742 | |||
2743 | /* Remove any existing table; this copes with multiple calls to | ||
2744 | * png_read_update_info. The warning is because building the gamma tables | ||
2745 | * multiple times is a performance hit - it's harmless but the ability to call | ||
2746 | * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible | ||
2747 | * to warn if the app introduces such a hit. | ||
2748 | */ | ||
2749 | if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL) | ||
2750 | { | ||
2751 | png_warning(png_ptr, "gamma table being rebuilt"); | ||
2752 | png_destroy_gamma_table(png_ptr); | ||
2753 | } | ||
2754 | |||
2755 | if (bit_depth <= 8) | ||
2756 | { | ||
2757 | png_build_8bit_table(png_ptr, &png_ptr->gamma_table, | ||
2758 | png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma, | ||
2759 | png_ptr->screen_gamma) : PNG_FP_1); | ||
2760 | |||
2761 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ | ||
2762 | defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ | ||
2763 | defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) | ||
2764 | if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) | ||
2765 | { | ||
2766 | png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1, | ||
2767 | png_reciprocal(png_ptr->gamma)); | ||
2768 | |||
2769 | png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1, | ||
2770 | png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : | ||
2771 | png_ptr->gamma/* Probably doing rgb_to_gray */); | ||
2772 | } | ||
2773 | #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ | ||
2774 | } | ||
2775 | else | ||
2776 | { | ||
2777 | png_byte shift, sig_bit; | ||
2778 | |||
2779 | if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) | ||
2780 | { | ||
2781 | sig_bit = png_ptr->sig_bit.red; | ||
2782 | |||
2783 | if (png_ptr->sig_bit.green > sig_bit) | ||
2784 | sig_bit = png_ptr->sig_bit.green; | ||
2785 | |||
2786 | if (png_ptr->sig_bit.blue > sig_bit) | ||
2787 | sig_bit = png_ptr->sig_bit.blue; | ||
2788 | } | ||
2789 | else | ||
2790 | sig_bit = png_ptr->sig_bit.gray; | ||
2791 | |||
2792 | /* 16-bit gamma code uses this equation: | ||
2793 | * | ||
2794 | * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8] | ||
2795 | * | ||
2796 | * Where 'iv' is the input color value and 'ov' is the output value - | ||
2797 | * pow(iv, gamma). | ||
2798 | * | ||
2799 | * Thus the gamma table consists of up to 256 256-entry tables. The table | ||
2800 | * is selected by the (8-gamma_shift) most significant of the low 8 bits of | ||
2801 | * the color value then indexed by the upper 8 bits: | ||
2802 | * | ||
2803 | * table[low bits][high 8 bits] | ||
2804 | * | ||
2805 | * So the table 'n' corresponds to all those 'iv' of: | ||
2806 | * | ||
2807 | * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1> | ||
2808 | * | ||
2809 | */ | ||
2810 | if (sig_bit > 0 && sig_bit < 16U) | ||
2811 | shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */ | ||
2812 | |||
2813 | else | ||
2814 | shift = 0; /* keep all 16 bits */ | ||
2815 | |||
2816 | if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) | ||
2817 | { | ||
2818 | /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively | ||
2819 | * the significant bits in the *input* when the output will | ||
2820 | * eventually be 8 bits. By default it is 11. | ||
2821 | */ | ||
2822 | if (shift < (16U - PNG_MAX_GAMMA_8)) | ||
2823 | shift = (16U - PNG_MAX_GAMMA_8); | ||
2824 | } | ||
2825 | |||
2826 | if (shift > 8U) | ||
2827 | shift = 8U; /* Guarantees at least one table! */ | ||
2828 | |||
2829 | png_ptr->gamma_shift = shift; | ||
2830 | |||
2831 | #ifdef PNG_16BIT_SUPPORTED | ||
2832 | /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now | ||
2833 | * PNG_COMPOSE). This effectively smashed the background calculation for | ||
2834 | * 16-bit output because the 8-bit table assumes the result will be reduced | ||
2835 | * to 8 bits. | ||
2836 | */ | ||
2837 | if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) | ||
2838 | #endif | ||
2839 | png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift, | ||
2840 | png_ptr->screen_gamma > 0 ? png_product2(png_ptr->gamma, | ||
2841 | png_ptr->screen_gamma) : PNG_FP_1); | ||
2842 | |||
2843 | #ifdef PNG_16BIT_SUPPORTED | ||
2844 | else | ||
2845 | png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift, | ||
2846 | png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma, | ||
2847 | png_ptr->screen_gamma) : PNG_FP_1); | ||
2848 | #endif | ||
2849 | |||
2850 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ | ||
2851 | defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ | ||
2852 | defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) | ||
2853 | if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) | ||
2854 | { | ||
2855 | png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift, | ||
2856 | png_reciprocal(png_ptr->gamma)); | ||
2857 | |||
2858 | /* Notice that the '16 from 1' table should be full precision, however | ||
2859 | * the lookup on this table still uses gamma_shift, so it can't be. | ||
2860 | * TODO: fix this. | ||
2861 | */ | ||
2862 | png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift, | ||
2863 | png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : | ||
2864 | png_ptr->gamma/* Probably doing rgb_to_gray */); | ||
2865 | } | ||
2866 | #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ | ||
2867 | } | ||
2868 | } | ||
2869 | #endif /* READ_GAMMA */ | ||
2870 | #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ | ||