-
Notifications
You must be signed in to change notification settings - Fork 2
/
Copy pathpngpriv.h
1947 lines (1721 loc) · 79.4 KB
/
pngpriv.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* pngpriv.h - private declarations for use inside libpng
*
* For conditions of distribution and use, see copyright notice in png.h
* Copyright (c) 1998-2014 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* Last changed in libpng 1.6.10 [March 6, 1014]]
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
/* The symbols declared in this file (including the functions declared
* as extern) are PRIVATE. They are not part of the libpng public
* interface, and are not recommended for use by regular applications.
* Some of them may become public in the future; others may stay private,
* change in an incompatible way, or even disappear.
* Although the libpng users are not forbidden to include this header,
* they should be well aware of the issues that may arise from doing so.
*/
#ifndef PNGPRIV_H
#define PNGPRIV_H
/* Feature Test Macros. The following are defined here to ensure that correctly
* implemented libraries reveal the APIs libpng needs to build and hide those
* that are not needed and potentially damaging to the compilation.
*
* Feature Test Macros must be defined before any system header is included (see
* POSIX 1003.1 2.8.2 "POSIX Symbols."
*
* These macros only have an effect if the operating system supports either
* POSIX 1003.1 or C99, or both. On other operating systems (particularly
* Windows/Visual Studio) there is no effect; the OS specific tests below are
* still required (as of 2011-05-02.)
*/
#define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
#ifndef PNG_VERSION_INFO_ONLY
/* Standard library headers not required by png.h: */
# include <stdlib.h>
# include <string.h>
#endif
#define PNGLIB_BUILD /*libpng is being built, not used*/
/* If HAVE_CONFIG_H is defined during the build then the build system must
* provide an appropriate "config.h" file on the include path. The header file
* must provide definitions as required below (search for "HAVE_CONFIG_H");
* see configure.ac for more details of the requirements. The macro
* "PNG_NO_CONFIG_H" is provided for maintainers to test for dependencies on
* 'configure'; define this macro to prevent the configure build including the
* configure generated config.h. Libpng is expected to compile without *any*
* special build system support on a reasonably ANSI-C compliant system.
*/
#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
# include <config.h>
/* Pick up the definition of 'restrict' from config.h if it was read: */
# define PNG_RESTRICT restrict
#endif
/* To support symbol prefixing it is necessary to know *before* including png.h
* whether the fixed point (and maybe other) APIs are exported, because if they
* are not internal definitions may be required. This is handled below just
* before png.h is included, but load the configuration now if it is available.
*/
#ifndef PNGLCONF_H
# include "pnglibconf.h"
#endif
/* Local renames may change non-exported API functions from png.h */
#if defined(PNG_PREFIX) && !defined(PNGPREFIX_H)
# include "pngprefix.h"
#endif
#ifdef PNG_USER_CONFIG
# include "pngusr.h"
/* These should have been defined in pngusr.h */
# ifndef PNG_USER_PRIVATEBUILD
# define PNG_USER_PRIVATEBUILD "Custom libpng build"
# endif
# ifndef PNG_USER_DLLFNAME_POSTFIX
# define PNG_USER_DLLFNAME_POSTFIX "Cb"
# endif
#endif
/* Compile time options.
* =====================
* In a multi-arch build the compiler may compile the code several times for the
* same object module, producing different binaries for different architectures.
* When this happens configure-time setting of the target host options cannot be
* done and this interferes with the handling of the ARM NEON optimizations, and
* possibly other similar optimizations. Put additional tests here; in general
* this is needed when the same option can be changed at both compile time and
* run time depending on the target OS (i.e. iOS vs Android.)
*
* NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
* this is not possible with certain compilers (Oracle SUN OS CC), as a result
* it is necessary to ensure that all extern functions that *might* be used
* regardless of $(CFLAGS) get declared in this file. The test on __ARM_NEON__
* below is one example of this behavior because it is controlled by the
* presence or not of -mfpu=neon on the GCC command line, it is possible to do
* this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
* do this.
*/
#define PNG_ARM_NEON_OPT 0
#ifndef PNG_ARM_NEON_OPT
/* ARM NEON optimizations are being controlled by the compiler settings,
* typically the target FPU. If the FPU has been set to NEON (-mfpu=neon
* with GCC) then the compiler will define __ARM_NEON__ and we can rely
* unconditionally on NEON instructions not crashing, otherwise we must
* disable use of NEON instructions.
*
* NOTE: at present these optimizations depend on 'ALIGNED_MEMORY', so they
* can only be turned on automatically if that is supported too. If
* PNG_ARM_NEON_OPT is set in CPPFLAGS (to >0) then arm/arm_init.c will fail
* to compile with an appropriate #error if ALIGNED_MEMORY has been turned
* off.
*
* Note that gcc-4.9 defines __ARM_NEON instead of __ARM_NEON__, so we
* check both variants.
*/
# if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
defined(PNG_ALIGNED_MEMORY_SUPPORTED)
# define PNG_ARM_NEON_OPT 2
# else
# define PNG_ARM_NEON_OPT 0
# endif
#endif
#if PNG_ARM_NEON_OPT > 0
/* NEON optimizations are to be at least considered by libpng, so enable the
* callbacks to do this.
*/
# define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
/* By default the 'intrinsics' code in arm/filter_neon_intrinsics.c is used
* if possible - if __ARM_NEON__ is set and the compiler version is not known
* to be broken. This is controlled by PNG_ARM_NEON_IMPLEMENTATION which can
* be:
*
* 1 The intrinsics code (the default with __ARM_NEON__)
* 2 The hand coded assembler (the default without __ARM_NEON__)
*
* It is possible to set PNG_ARM_NEON_IMPLEMENTATION in CPPFLAGS, however
* this is *NOT* supported and may cease to work even after a minor revision
* to libpng. It *is* valid to do this for testing purposes, e.g. speed
* testing or a new compiler, but the results should be communicated to the
* libpng implementation list for incorporation in the next minor release.
*/
# ifndef PNG_ARM_NEON_IMPLEMENTATION
# if defined(__ARM_NEON__) || defined(__ARM_NEON)
# if defined(__clang__)
/* At present it is unknown by the libpng developers which versions
* of clang support the intrinsics, however some or perhaps all
* versions do not work with the assembler so this may be
* irrelevant, so just use the default (do nothing here.)
*/
# elif defined(__GNUC__)
/* GCC 4.5.4 NEON support is known to be broken. 4.6.3 is known to
* work, so if this *is* GCC, or G++, look for a version >4.5
*/
# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
# define PNG_ARM_NEON_IMPLEMENTATION 2
# endif /* no GNUC support */
# endif /* __GNUC__ */
# else /* !defined __ARM_NEON__ */
/* The 'intrinsics' code simply won't compile without this -mfpu=neon:
*/
# define PNG_ARM_NEON_IMPLEMENTATION 2
# endif /* __ARM_NEON__ */
# endif /* !defined PNG_ARM_NEON_IMPLEMENTATION */
# ifndef PNG_ARM_NEON_IMPLEMENTATION
/* Use the intrinsics code by default. */
# define PNG_ARM_NEON_IMPLEMENTATION 1
# endif
#endif /* PNG_ARM_NEON_OPT > 0 */
/* Is this a build of a DLL where compilation of the object modules requires
* different preprocessor settings to those required for a simple library? If
* so PNG_BUILD_DLL must be set.
*
* If libpng is used inside a DLL but that DLL does not export the libpng APIs
* PNG_BUILD_DLL must not be set. To avoid the code below kicking in build a
* static library of libpng then link the DLL against that.
*/
#ifndef PNG_BUILD_DLL
# ifdef DLL_EXPORT
/* This is set by libtool when files are compiled for a DLL; libtool
* always compiles twice, even on systems where it isn't necessary. Set
* PNG_BUILD_DLL in case it is necessary:
*/
# define PNG_BUILD_DLL
# else
# ifdef _WINDLL
/* This is set by the Microsoft Visual Studio IDE in projects that
* build a DLL. It can't easily be removed from those projects (it
* isn't visible in the Visual Studio UI) so it is a fairly reliable
* indication that PNG_IMPEXP needs to be set to the DLL export
* attributes.
*/
# define PNG_BUILD_DLL
# else
# ifdef __DLL__
/* This is set by the Borland C system when compiling for a DLL
* (as above.)
*/
# define PNG_BUILD_DLL
# else
/* Add additional compiler cases here. */
# endif
# endif
# endif
#endif /* Setting PNG_BUILD_DLL if required */
/* See pngconf.h for more details: the builder of the library may set this on
* the command line to the right thing for the specific compilation system or it
* may be automagically set above (at present we know of no system where it does
* need to be set on the command line.)
*
* PNG_IMPEXP must be set here when building the library to prevent pngconf.h
* setting it to the "import" setting for a DLL build.
*/
#ifndef PNG_IMPEXP
# ifdef PNG_BUILD_DLL
# define PNG_IMPEXP PNG_DLL_EXPORT
# else
/* Not building a DLL, or the DLL doesn't require specific export
* definitions.
*/
# define PNG_IMPEXP
# endif
#endif
/* No warnings for private or deprecated functions in the build: */
#ifndef PNG_DEPRECATED
# define PNG_DEPRECATED
#endif
#ifndef PNG_PRIVATE
# define PNG_PRIVATE
#endif
/* Symbol preprocessing support.
*
* To enable listing global, but internal, symbols the following macros should
* always be used to declare an extern data or function object in this file.
*/
#ifndef PNG_INTERNAL_DATA
# define PNG_INTERNAL_DATA(type, name, array) extern type name array
#endif
#ifndef PNG_INTERNAL_FUNCTION
# define PNG_INTERNAL_FUNCTION(type, name, args, attributes)\
extern PNG_FUNCTION(type, name, args, PNG_EMPTY attributes)
#endif
#ifndef PNG_INTERNAL_CALLBACK
# define PNG_INTERNAL_CALLBACK(type, name, args, attributes)\
extern PNG_FUNCTION(type, (PNGCBAPI name), args, PNG_EMPTY attributes)
#endif
/* If floating or fixed point APIs are disabled they may still be compiled
* internally. To handle this make sure they are declared as the appropriate
* internal extern function (otherwise the symbol prefixing stuff won't work and
* the functions will be used without definitions.)
*
* NOTE: although all the API functions are declared here they are not all
* actually built! Because the declarations are still made it is necessary to
* fake out types that they depend on.
*/
#ifndef PNG_FP_EXPORT
# ifndef PNG_FLOATING_POINT_SUPPORTED
# define PNG_FP_EXPORT(ordinal, type, name, args)\
PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
# ifndef PNG_VERSION_INFO_ONLY
typedef struct png_incomplete png_double;
typedef png_double* png_doublep;
typedef const png_double* png_const_doublep;
typedef png_double** png_doublepp;
# endif
# endif
#endif
#ifndef PNG_FIXED_EXPORT
# ifndef PNG_FIXED_POINT_SUPPORTED
# define PNG_FIXED_EXPORT(ordinal, type, name, args)\
PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
# endif
#endif
#include "png.h"
/* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
#ifndef PNG_DLL_EXPORT
# define PNG_DLL_EXPORT
#endif
/* SECURITY and SAFETY:
*
* By default libpng is built without any internal limits on image size,
* individual heap (png_malloc) allocations or the total amount of memory used.
* If PNG_SAFE_LIMITS_SUPPORTED is defined, however, the limits below are used
* (unless individually overridden). These limits are believed to be fairly
* safe, but builders of secure systems should verify the values against the
* real system capabilities.
*/
#ifdef PNG_SAFE_LIMITS_SUPPORTED
/* 'safe' limits */
# ifndef PNG_USER_WIDTH_MAX
# define PNG_USER_WIDTH_MAX 1000000
# endif
# ifndef PNG_USER_HEIGHT_MAX
# define PNG_USER_HEIGHT_MAX 1000000
# endif
# ifndef PNG_USER_CHUNK_CACHE_MAX
# define PNG_USER_CHUNK_CACHE_MAX 128
# endif
# ifndef PNG_USER_CHUNK_MALLOC_MAX
# define PNG_USER_CHUNK_MALLOC_MAX 8000000
# endif
#else
/* values for no limits */
# ifndef PNG_USER_WIDTH_MAX
# define PNG_USER_WIDTH_MAX 0x7fffffff
# endif
# ifndef PNG_USER_HEIGHT_MAX
# define PNG_USER_HEIGHT_MAX 0x7fffffff
# endif
# ifndef PNG_USER_CHUNK_CACHE_MAX
# define PNG_USER_CHUNK_CACHE_MAX 0
# endif
# ifndef PNG_USER_CHUNK_MALLOC_MAX
# define PNG_USER_CHUNK_MALLOC_MAX 0
# endif
#endif
/* Moved to pngpriv.h at libpng-1.5.0 */
/* NOTE: some of these may have been used in external applications as
* these definitions were exposed in pngconf.h prior to 1.5.
*/
/* If you are running on a machine where you cannot allocate more
* than 64K of memory at once, uncomment this. While libpng will not
* normally need that much memory in a chunk (unless you load up a very
* large file), zlib needs to know how big of a chunk it can use, and
* libpng thus makes sure to check any memory allocation to verify it
* will fit into memory.
*
* zlib provides 'MAXSEG_64K' which, if defined, indicates the
* same limit and pngconf.h (already included) sets the limit
* if certain operating systems are detected.
*/
#if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
# define PNG_MAX_MALLOC_64K
#endif
#ifndef PNG_UNUSED
/* Unused formal parameter warnings are silenced using the following macro
* which is expected to have no bad effects on performance (optimizing
* compilers will probably remove it entirely). Note that if you replace
* it with something other than whitespace, you must include the terminating
* semicolon.
*/
# define PNG_UNUSED(param) (void)param;
#endif
/* Just a little check that someone hasn't tried to define something
* contradictory.
*/
#if (PNG_ZBUF_SIZE > 65536L) && defined(PNG_MAX_MALLOC_64K)
# undef PNG_ZBUF_SIZE
# define PNG_ZBUF_SIZE 65536L
#endif
/* If warnings or errors are turned off the code is disabled or redirected here.
* From 1.5.4 functions have been added to allow very limited formatting of
* error and warning messages - this code will also be disabled here.
*/
#ifdef PNG_WARNINGS_SUPPORTED
# define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
#else
# define png_warning_parameter(p,number,string) ((void)0)
# define png_warning_parameter_unsigned(p,number,format,value) ((void)0)
# define png_warning_parameter_signed(p,number,format,value) ((void)0)
# define png_formatted_warning(pp,p,message) ((void)(pp))
# define PNG_WARNING_PARAMETERS(p)
#endif
#ifndef PNG_ERROR_TEXT_SUPPORTED
# define png_fixed_error(s1,s2) png_err(s1)
#endif
/* C allows up-casts from (void*) to any pointer and (const void*) to any
* pointer to a const object. C++ regards this as a type error and requires an
* explicit, static, cast and provides the static_cast<> rune to ensure that
* const is not cast away.
*/
#ifdef __cplusplus
# define png_voidcast(type, value) static_cast<type>(value)
# define png_constcast(type, value) const_cast<type>(value)
# define png_aligncast(type, value) \
static_cast<type>(static_cast<void*>(value))
# define png_aligncastconst(type, value) \
static_cast<type>(static_cast<const void*>(value))
#else
# define png_voidcast(type, value) (value)
# define png_constcast(type, value) ((type)(value))
# define png_aligncast(type, value) ((void*)(value))
# define png_aligncastconst(type, value) ((const void*)(value))
#endif /* __cplusplus */
/* Some fixed point APIs are still required even if not exported because
* they get used by the corresponding floating point APIs. This magic
* deals with this:
*/
#ifdef PNG_FIXED_POINT_SUPPORTED
# define PNGFAPI PNGAPI
#else
# define PNGFAPI /* PRIVATE */
#endif
#ifndef PNG_VERSION_INFO_ONLY
/* Other defines specific to compilers can go here. Try to keep
* them inside an appropriate ifdef/endif pair for portability.
*/
#if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
/* png.c requires the following ANSI-C constants if the conversion of
* floating point to ASCII is implemented therein:
*
* DBL_DIG Maximum number of decimal digits (can be set to any constant)
* DBL_MIN Smallest normalized fp number (can be set to an arbitrary value)
* DBL_MAX Maximum floating point number (can be set to an arbitrary value)
*/
# include <float.h>
# if (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
defined(THINK_C) || defined(__SC__) || defined(TARGET_OS_MAC)
/* We need to check that <math.h> hasn't already been included earlier
* as it seems it doesn't agree with <fp.h>, yet we should really use
* <fp.h> if possible.
*/
# if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
# include <fp.h>
# endif
# else
# include <math.h>
# endif
# if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
/* Amiga SAS/C: We must include builtin FPU functions when compiling using
* MATH=68881
*/
# include <m68881.h>
# endif
#endif
/* This provides the non-ANSI (far) memory allocation routines. */
#if defined(__TURBOC__) && defined(__MSDOS__)
# include <mem.h>
# include <alloc.h>
#endif
#if defined(WIN32) || defined(_Windows) || defined(_WINDOWS) || \
defined(_WIN32) || defined(__WIN32__)
# include <windows.h> /* defines _WINDOWS_ macro */
#endif
#endif /* PNG_VERSION_INFO_ONLY */
/* Moved here around 1.5.0beta36 from pngconf.h */
/* Users may want to use these so they are not private. Any library
* functions that are passed far data must be model-independent.
*/
/* Memory model/platform independent fns */
#ifndef PNG_ABORT
# ifdef _WINDOWS_
# define PNG_ABORT() ExitProcess(0)
# else
# define PNG_ABORT() abort()
# endif
#endif
/* These macros may need to be architecture dependent. */
#define PNG_ALIGN_NONE 0 /* do not use data alignment */
#define PNG_ALIGN_ALWAYS 1 /* assume unaligned accesses are OK */
#ifdef offsetof
# define PNG_ALIGN_OFFSET 2 /* use offsetof to determine alignment */
#else
# define PNG_ALIGN_OFFSET -1 /* prevent the use of this */
#endif
#define PNG_ALIGN_SIZE 3 /* use sizeof to determine alignment */
#ifndef PNG_ALIGN_TYPE
/* Default to using aligned access optimizations and requiring alignment to a
* multiple of the data type size. Override in a compiler specific fashion
* if necessary by inserting tests here:
*/
# define PNG_ALIGN_TYPE PNG_ALIGN_SIZE
#endif
#if PNG_ALIGN_TYPE == PNG_ALIGN_SIZE
/* This is used because in some compiler implementations non-aligned
* structure members are supported, so the offsetof approach below fails.
* Set PNG_ALIGN_SIZE=0 for compiler combinations where unaligned access
* is good for performance. Do not do this unless you have tested the result
* and understand it.
*/
# define png_alignof(type) (sizeof (type))
#else
# if PNG_ALIGN_TYPE == PNG_ALIGN_OFFSET
# define png_alignof(type) offsetof(struct{char c; type t;}, t)
# else
# if PNG_ALIGN_TYPE == PNG_ALIGN_ALWAYS
# define png_alignof(type) (1)
# endif
/* Else leave png_alignof undefined to prevent use thereof */
# endif
#endif
/* This implicitly assumes alignment is always to a power of 2. */
#ifdef png_alignof
# define png_isaligned(ptr, type)\
((((const char*)ptr-(const char*)0) & (png_alignof(type)-1)) == 0)
#else
# define png_isaligned(ptr, type) 0
#endif
/* End of memory model/platform independent support */
/* End of 1.5.0beta36 move from pngconf.h */
/* CONSTANTS and UTILITY MACROS
* These are used internally by libpng and not exposed in the API
*/
/* Various modes of operation. Note that after an init, mode is set to
* zero automatically when the structure is created. Three of these
* are defined in png.h because they need to be visible to applications
* that call png_set_unknown_chunk().
*/
/* #define PNG_HAVE_IHDR 0x01 (defined in png.h) */
/* #define PNG_HAVE_PLTE 0x02 (defined in png.h) */
#define PNG_HAVE_IDAT 0x04
/* #define PNG_AFTER_IDAT 0x08 (defined in png.h) */
#define PNG_HAVE_IEND 0x10
/* 0x20 (unused) */
/* 0x40 (unused) */
/* 0x80 (unused) */
#define PNG_HAVE_CHUNK_HEADER 0x100
#define PNG_WROTE_tIME 0x200
#define PNG_WROTE_INFO_BEFORE_PLTE 0x400
#define PNG_BACKGROUND_IS_GRAY 0x800
#define PNG_HAVE_PNG_SIGNATURE 0x1000
#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
/* 0x4000 (unused) */
#define PNG_IS_READ_STRUCT 0x8000 /* Else is a write struct */
/* Flags for the transformations the PNG library does on the image data */
#define PNG_BGR 0x0001
#define PNG_INTERLACE 0x0002
#define PNG_PACK 0x0004
#define PNG_SHIFT 0x0008
#define PNG_SWAP_BYTES 0x0010
#define PNG_INVERT_MONO 0x0020
#define PNG_QUANTIZE 0x0040
#define PNG_COMPOSE 0x0080 /* Was PNG_BACKGROUND */
#define PNG_BACKGROUND_EXPAND 0x0100
#define PNG_EXPAND_16 0x0200 /* Added to libpng 1.5.2 */
#define PNG_16_TO_8 0x0400 /* Becomes 'chop' in 1.5.4 */
#define PNG_RGBA 0x0800
#define PNG_EXPAND 0x1000
#define PNG_GAMMA 0x2000
#define PNG_GRAY_TO_RGB 0x4000
#define PNG_FILLER 0x8000
#define PNG_PACKSWAP 0x10000
#define PNG_SWAP_ALPHA 0x20000
#define PNG_STRIP_ALPHA 0x40000
#define PNG_INVERT_ALPHA 0x80000
#define PNG_USER_TRANSFORM 0x100000
#define PNG_RGB_TO_GRAY_ERR 0x200000
#define PNG_RGB_TO_GRAY_WARN 0x400000
#define PNG_RGB_TO_GRAY 0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
#define PNG_ENCODE_ALPHA 0x800000 /* Added to libpng-1.5.4 */
#define PNG_ADD_ALPHA 0x1000000 /* Added to libpng-1.2.7 */
#define PNG_EXPAND_tRNS 0x2000000 /* Added to libpng-1.2.9 */
#define PNG_SCALE_16_TO_8 0x4000000 /* Added to libpng-1.5.4 */
/* 0x8000000 unused */
/* 0x10000000 unused */
/* 0x20000000 unused */
/* 0x40000000 unused */
/* Flags for png_create_struct */
#define PNG_STRUCT_PNG 0x0001
#define PNG_STRUCT_INFO 0x0002
/* Scaling factor for filter heuristic weighting calculations */
#define PNG_WEIGHT_FACTOR (1<<(PNG_WEIGHT_SHIFT))
#define PNG_COST_FACTOR (1<<(PNG_COST_SHIFT))
/* Flags for the png_ptr->flags rather than declaring a byte for each one */
#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY 0x0001
#define PNG_FLAG_ZSTREAM_INITIALIZED 0x0002 /* Added to libpng-1.6.0 */
/* 0x0004 unused */
#define PNG_FLAG_ZSTREAM_ENDED 0x0008 /* Added to libpng-1.6.0 */
/* 0x0010 unused */
/* 0x0020 unused */
#define PNG_FLAG_ROW_INIT 0x0040
#define PNG_FLAG_FILLER_AFTER 0x0080
#define PNG_FLAG_CRC_ANCILLARY_USE 0x0100
#define PNG_FLAG_CRC_ANCILLARY_NOWARN 0x0200
#define PNG_FLAG_CRC_CRITICAL_USE 0x0400
#define PNG_FLAG_CRC_CRITICAL_IGNORE 0x0800
#define PNG_FLAG_ASSUME_sRGB 0x1000 /* Added to libpng-1.5.4 */
#define PNG_FLAG_OPTIMIZE_ALPHA 0x2000 /* Added to libpng-1.5.4 */
#define PNG_FLAG_DETECT_UNINITIALIZED 0x4000 /* Added to libpng-1.5.4 */
/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS 0x8000 */
/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS 0x10000 */
#define PNG_FLAG_LIBRARY_MISMATCH 0x20000
#define PNG_FLAG_STRIP_ERROR_NUMBERS 0x40000
#define PNG_FLAG_STRIP_ERROR_TEXT 0x80000
#define PNG_FLAG_BENIGN_ERRORS_WARN 0x100000 /* Added to libpng-1.4.0 */
#define PNG_FLAG_APP_WARNINGS_WARN 0x200000 /* Added to libpng-1.6.0 */
#define PNG_FLAG_APP_ERRORS_WARN 0x400000 /* Added to libpng-1.6.0 */
/* 0x800000 unused */
/* 0x1000000 unused */
/* 0x2000000 unused */
/* 0x4000000 unused */
/* 0x8000000 unused */
/* 0x10000000 unused */
/* 0x20000000 unused */
/* 0x40000000 unused */
#define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
PNG_FLAG_CRC_ANCILLARY_NOWARN)
#define PNG_FLAG_CRC_CRITICAL_MASK (PNG_FLAG_CRC_CRITICAL_USE | \
PNG_FLAG_CRC_CRITICAL_IGNORE)
#define PNG_FLAG_CRC_MASK (PNG_FLAG_CRC_ANCILLARY_MASK | \
PNG_FLAG_CRC_CRITICAL_MASK)
/* Save typing and make code easier to understand */
#define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
abs((int)((c1).green) - (int)((c2).green)) + \
abs((int)((c1).blue) - (int)((c2).blue)))
/* Added to libpng-1.6.0: scale a 16-bit value in the range 0..65535 to 0..255
* by dividing by 257 *with rounding*. This macro is exact for the given range.
* See the discourse in pngrtran.c png_do_scale_16_to_8. The values in the
* macro were established by experiment (modifying the added value). The macro
* has a second variant that takes a value already scaled by 255 and divides by
* 65535 - this has a maximum error of .502. Over the range 0..65535*65535 it
* only gives off-by-one errors and only for 0.5% (1 in 200) of the values.
*/
#define PNG_DIV65535(v24) (((v24) + 32895) >> 16)
#define PNG_DIV257(v16) PNG_DIV65535((png_uint_32)(v16) * 255)
/* Added to libpng-1.2.6 JB */
#define PNG_ROWBYTES(pixel_bits, width) \
((pixel_bits) >= 8 ? \
((png_size_t)(width) * (((png_size_t)(pixel_bits)) >> 3)) : \
(( ((png_size_t)(width) * ((png_size_t)(pixel_bits))) + 7) >> 3) )
/* PNG_OUT_OF_RANGE returns true if value is outside the range
* ideal-delta..ideal+delta. Each argument is evaluated twice.
* "ideal" and "delta" should be constants, normally simple
* integers, "value" a variable. Added to libpng-1.2.6 JB
*/
#define PNG_OUT_OF_RANGE(value, ideal, delta) \
( (value) < (ideal)-(delta) || (value) > (ideal)+(delta) )
/* Conversions between fixed and floating point, only defined if
* required (to make sure the code doesn't accidentally use float
* when it is supposedly disabled.)
*/
#ifdef PNG_FLOATING_POINT_SUPPORTED
/* The floating point conversion can't overflow, though it can and
* does lose accuracy relative to the original fixed point value.
* In practice this doesn't matter because png_fixed_point only
* stores numbers with very low precision. The png_ptr and s
* arguments are unused by default but are there in case error
* checking becomes a requirement.
*/
#define png_float(png_ptr, fixed, s) (.00001 * (fixed))
/* The fixed point conversion performs range checking and evaluates
* its argument multiple times, so must be used with care. The
* range checking uses the PNG specification values for a signed
* 32 bit fixed point value except that the values are deliberately
* rounded-to-zero to an integral value - 21474 (21474.83 is roughly
* (2^31-1) * 100000). 's' is a string that describes the value being
* converted.
*
* NOTE: this macro will raise a png_error if the range check fails,
* therefore it is normally only appropriate to use this on values
* that come from API calls or other sources where an out of range
* error indicates a programming error, not a data error!
*
* NOTE: by default this is off - the macro is not used - because the
* function call saves a lot of code.
*/
#ifdef PNG_FIXED_POINT_MACRO_SUPPORTED
#define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
#endif
/* else the corresponding function is defined below, inside the scope of the
* cplusplus test.
*/
#endif
/* Constants for known chunk types. If you need to add a chunk, define the name
* here. For historical reasons these constants have the form png_<name>; i.e.
* the prefix is lower case. Please use decimal values as the parameters to
* match the ISO PNG specification and to avoid relying on the C locale
* interpretation of character values.
*
* Prior to 1.5.6 these constants were strings, as of 1.5.6 png_uint_32 values
* are computed and a new macro (PNG_STRING_FROM_CHUNK) added to allow a string
* to be generated if required.
*
* PNG_32b correctly produces a value shifted by up to 24 bits, even on
* architectures where (int) is only 16 bits.
*/
#define PNG_32b(b,s) ((png_uint_32)(b) << (s))
#define PNG_U32(b1,b2,b3,b4) \
(PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0))
/* Constants for known chunk types.
*
* MAINTAINERS: If you need to add a chunk, define the name here.
* For historical reasons these constants have the form png_<name>; i.e.
* the prefix is lower case. Please use decimal values as the parameters to
* match the ISO PNG specification and to avoid relying on the C locale
* interpretation of character values. Please keep the list sorted.
*
* Notice that PNG_U32 is used to define a 32-bit value for the 4 byte chunk
* type. In fact the specification does not express chunk types this way,
* however using a 32-bit value means that the chunk type can be read from the
* stream using exactly the same code as used for a 32-bit unsigned value and
* can be examined far more efficiently (using one arithmetic compare).
*
* Prior to 1.5.6 the chunk type constants were expressed as C strings. The
* libpng API still uses strings for 'unknown' chunks and a macro,
* PNG_STRING_FROM_CHUNK, allows a string to be generated if required. Notice
* that for portable code numeric values must still be used; the string "IHDR"
* is not portable and neither is PNG_U32('I', 'H', 'D', 'R').
*
* In 1.7.0 the definitions will be made public in png.h to avoid having to
* duplicate the same definitions in application code.
*/
#define png_IDAT PNG_U32( 73, 68, 65, 84)
#define png_IEND PNG_U32( 73, 69, 78, 68)
#define png_IHDR PNG_U32( 73, 72, 68, 82)
#define png_PLTE PNG_U32( 80, 76, 84, 69)
#define png_bKGD PNG_U32( 98, 75, 71, 68)
#define png_cHRM PNG_U32( 99, 72, 82, 77)
#define png_fRAc PNG_U32(102, 82, 65, 99) /* registered, not defined */
#define png_gAMA PNG_U32(103, 65, 77, 65)
#define png_gIFg PNG_U32(103, 73, 70, 103)
#define png_gIFt PNG_U32(103, 73, 70, 116) /* deprecated */
#define png_gIFx PNG_U32(103, 73, 70, 120)
#define png_hIST PNG_U32(104, 73, 83, 84)
#define png_iCCP PNG_U32(105, 67, 67, 80)
#define png_iTXt PNG_U32(105, 84, 88, 116)
#define png_oFFs PNG_U32(111, 70, 70, 115)
#define png_pCAL PNG_U32(112, 67, 65, 76)
#define png_pHYs PNG_U32(112, 72, 89, 115)
#define png_sBIT PNG_U32(115, 66, 73, 84)
#define png_sCAL PNG_U32(115, 67, 65, 76)
#define png_sPLT PNG_U32(115, 80, 76, 84)
#define png_sRGB PNG_U32(115, 82, 71, 66)
#define png_sTER PNG_U32(115, 84, 69, 82)
#define png_tEXt PNG_U32(116, 69, 88, 116)
#define png_tIME PNG_U32(116, 73, 77, 69)
#define png_tRNS PNG_U32(116, 82, 78, 83)
#define png_zTXt PNG_U32(122, 84, 88, 116)
/* The following will work on (signed char*) strings, whereas the get_uint_32
* macro will fail on top-bit-set values because of the sign extension.
*/
#define PNG_CHUNK_FROM_STRING(s)\
PNG_U32(0xff&(s)[0], 0xff&(s)[1], 0xff&(s)[2], 0xff&(s)[3])
/* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
* signed and the argument is a (char[]) This macro will fail miserably on
* systems where (char) is more than 8 bits.
*/
#define PNG_STRING_FROM_CHUNK(s,c)\
(void)(((char*)(s))[0]=(char)((c)>>24), ((char*)(s))[1]=(char)((c)>>16),\
((char*)(s))[2]=(char)((c)>>8), ((char*)(s))[3]=(char)((c)))
/* Do the same but terminate with a null character. */
#define PNG_CSTRING_FROM_CHUNK(s,c)\
(void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)
/* Test on flag values as defined in the spec (section 5.4): */
#define PNG_CHUNK_ANCILLARY(c) (1 & ((c) >> 29))
#define PNG_CHUNK_CRITICAL(c) (!PNG_CHUNK_ANCILLARY(c))
#define PNG_CHUNK_PRIVATE(c) (1 & ((c) >> 21))
#define PNG_CHUNK_RESERVED(c) (1 & ((c) >> 13))
#define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >> 5))
/* Gamma values (new at libpng-1.5.4): */
#define PNG_GAMMA_MAC_OLD 151724 /* Assume '1.8' is really 2.2/1.45! */
#define PNG_GAMMA_MAC_INVERSE 65909
#define PNG_GAMMA_sRGB_INVERSE 45455
/* Almost everything below is C specific; the #defines above can be used in
* non-C code (so long as it is C-preprocessed) the rest of this stuff cannot.
*/
#ifndef PNG_VERSION_INFO_ONLY
#include "pngstruct.h"
#include "pnginfo.h"
/* Validate the include paths - the include path used to generate pnglibconf.h
* must match that used in the build, or we must be using pnglibconf.h.prebuilt:
*/
#if PNG_ZLIB_VERNUM != 0 && PNG_ZLIB_VERNUM != ZLIB_VERNUM
# error ZLIB_VERNUM != PNG_ZLIB_VERNUM \
"-I (include path) error: see the notes in pngpriv.h"
/* This means that when pnglibconf.h was built the copy of zlib.h that it
* used is not the same as the one being used here. Because the build of
* libpng makes decisions to use inflateInit2 and inflateReset2 based on the
* zlib version number and because this affects handling of certain broken
* PNG files the -I directives must match.
*
* The most likely explanation is that you passed a -I in CFLAGS. This will
* not work; all the preprocessor directories and in particular all the -I
* directives must be in CPPFLAGS.
*/
#endif
/* This is used for 16 bit gamma tables -- only the top level pointers are
* const; this could be changed:
*/
typedef const png_uint_16p * png_const_uint_16pp;
/* Added to libpng-1.5.7: sRGB conversion tables */
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_table, [256]);
/* Convert from an sRGB encoded value 0..255 to a 16-bit linear value,
* 0..65535. This table gives the closest 16-bit answers (no errors).
*/
#endif
PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_base, [512]);
PNG_INTERNAL_DATA(const png_byte, png_sRGB_delta, [512]);
#define PNG_sRGB_FROM_LINEAR(linear) ((png_byte)((png_sRGB_base[(linear)>>15] +\
((((linear)&0x7fff)*png_sRGB_delta[(linear)>>15])>>12)) >> 8))
/* Given a value 'linear' in the range 0..255*65535 calculate the 8-bit sRGB
* encoded value with maximum error 0.646365. Note that the input is not a
* 16-bit value; it has been multiplied by 255! */
#endif /* PNG_SIMPLIFIED_READ/WRITE */
/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/* Internal functions; these are not exported from a DLL however because they
* are used within several of the C source files they have to be C extern.
*
* All of these functions must be declared with PNG_INTERNAL_FUNCTION.
*/
/* Zlib support */
#define PNG_UNEXPECTED_ZLIB_RETURN (-7)
PNG_INTERNAL_FUNCTION(void, png_zstream_error,(png_structrp png_ptr, int ret),
PNG_EMPTY);
/* Used by the zlib handling functions to ensure that z_stream::msg is always
* set before they return.
*/
#ifdef PNG_WRITE_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_free_buffer_list,(png_structrp png_ptr,
png_compression_bufferp *list),PNG_EMPTY);
/* Free the buffer list used by the compressed write code. */
#endif
#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
!defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
(defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
(defined(PNG_sCAL_SUPPORTED) && \
defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
PNG_INTERNAL_FUNCTION(png_fixed_point,png_fixed,(png_const_structrp png_ptr,
double fp, png_const_charp text),PNG_EMPTY);
#endif
/* Check the user version string for compatibility, returns false if the version
* numbers aren't compatible.
*/
PNG_INTERNAL_FUNCTION(int,png_user_version_check,(png_structrp png_ptr,
png_const_charp user_png_ver),PNG_EMPTY);
/* Internal base allocator - no messages, NULL on failure to allocate. This
* does, however, call the application provided allocator and that could call
* png_error (although that would be a bug in the application implementation.)
*/
PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_base,(png_const_structrp png_ptr,
png_alloc_size_t size),PNG_ALLOCATED);
#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
/* Internal array allocator, outputs no error or warning messages on failure,
* just returns NULL.
*/
PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_array,(png_const_structrp png_ptr,
int nelements, size_t element_size),PNG_ALLOCATED);
/* The same but an existing array is extended by add_elements. This function
* also memsets the new elements to 0 and copies the old elements. The old
* array is not freed or altered.
*/
PNG_INTERNAL_FUNCTION(png_voidp,png_realloc_array,(png_const_structrp png_ptr,
png_const_voidp array, int old_elements, int add_elements,
size_t element_size),PNG_ALLOCATED);
#endif /* text, sPLT or unknown chunks */
/* Magic to create a struct when there is no struct to call the user supplied
* memory allocators. Because error handling has not been set up the memory
* handlers can't safely call png_error, but this is an obscure and undocumented
* restriction so libpng has to assume that the 'free' handler, at least, might
* call png_error.
*/
PNG_INTERNAL_FUNCTION(png_structp,png_create_png_struct,
(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn,
png_free_ptr free_fn),PNG_ALLOCATED);
/* Free memory from internal libpng struct */
PNG_INTERNAL_FUNCTION(void,png_destroy_png_struct,(png_structrp png_ptr),
PNG_EMPTY);
/* Free an allocated jmp_buf (always succeeds) */
PNG_INTERNAL_FUNCTION(void,png_free_jmpbuf,(png_structrp png_ptr),PNG_EMPTY);
/* Function to allocate memory for zlib. PNGAPI is disallowed. */
PNG_INTERNAL_FUNCTION(voidpf,png_zalloc,(voidpf png_ptr, uInt items, uInt size),
PNG_ALLOCATED);
/* Function to free memory for zlib. PNGAPI is disallowed. */
PNG_INTERNAL_FUNCTION(void,png_zfree,(voidpf png_ptr, voidpf ptr),PNG_EMPTY);
/* Next four functions are used internally as callbacks. PNGCBAPI is required
* but not PNG_EXPORT. PNGAPI added at libpng version 1.2.3, changed to
* PNGCBAPI at 1.5.0
*/
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_read_data,(png_structp png_ptr,
png_bytep data, png_size_t length),PNG_EMPTY);
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_push_fill_buffer,(png_structp png_ptr,
png_bytep buffer, png_size_t length),PNG_EMPTY);
#endif
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_write_data,(png_structp png_ptr,
png_bytep data, png_size_t length),PNG_EMPTY);
#ifdef PNG_WRITE_FLUSH_SUPPORTED
# ifdef PNG_STDIO_SUPPORTED
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_flush,(png_structp png_ptr),
PNG_EMPTY);
# endif
#endif
/* Reset the CRC variable */
PNG_INTERNAL_FUNCTION(void,png_reset_crc,(png_structrp png_ptr),PNG_EMPTY);
/* Write the "data" buffer to whatever output you are using */
PNG_INTERNAL_FUNCTION(void,png_write_data,(png_structrp png_ptr,
png_const_bytep data, png_size_t length),PNG_EMPTY);
/* Read and check the PNG file signature */
PNG_INTERNAL_FUNCTION(void,png_read_sig,(png_structrp png_ptr,
png_inforp info_ptr),PNG_EMPTY);
/* Read the chunk header (length + type name) */
PNG_INTERNAL_FUNCTION(png_uint_32,png_read_chunk_header,(png_structrp png_ptr),
PNG_EMPTY);
/* Read data from whatever input you are using into the "data" buffer */
PNG_INTERNAL_FUNCTION(void,png_read_data,(png_structrp png_ptr, png_bytep data,
png_size_t length),PNG_EMPTY);
/* Read bytes into buf, and update png_ptr->crc */
PNG_INTERNAL_FUNCTION(void,png_crc_read,(png_structrp png_ptr, png_bytep buf,
png_uint_32 length),PNG_EMPTY);