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      1 
      2 /* pngpriv.h - private declarations for use inside libpng
      3  *
      4  * Last changed in libpng 1.6.22 [May 26, 2016]
      5  * Copyright (c) 1998-2002,2004,2006-2016 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 /* The symbols declared in this file (including the functions declared
     15  * as extern) are PRIVATE.  They are not part of the libpng public
     16  * interface, and are not recommended for use by regular applications.
     17  * Some of them may become public in the future; others may stay private,
     18  * change in an incompatible way, or even disappear.
     19  * Although the libpng users are not forbidden to include this header,
     20  * they should be well aware of the issues that may arise from doing so.
     21  */
     22 
     23 #ifndef PNGPRIV_H
     24 #define PNGPRIV_H
     25 
     26 /* Feature Test Macros.  The following are defined here to ensure that correctly
     27  * implemented libraries reveal the APIs libpng needs to build and hide those
     28  * that are not needed and potentially damaging to the compilation.
     29  *
     30  * Feature Test Macros must be defined before any system header is included (see
     31  * POSIX 1003.1 2.8.2 "POSIX Symbols."
     32  *
     33  * These macros only have an effect if the operating system supports either
     34  * POSIX 1003.1 or C99, or both.  On other operating systems (particularly
     35  * Windows/Visual Studio) there is no effect; the OS specific tests below are
     36  * still required (as of 2011-05-02.)
     37  */
     38 #define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
     39 
     40 #ifndef PNG_VERSION_INFO_ONLY
     41 /* Standard library headers not required by png.h: */
     42 #  include <stdlib.h>
     43 #  include <string.h>
     44 #endif
     45 
     46 #define PNGLIB_BUILD /*libpng is being built, not used*/
     47 
     48 /* If HAVE_CONFIG_H is defined during the build then the build system must
     49  * provide an appropriate "config.h" file on the include path.  The header file
     50  * must provide definitions as required below (search for "HAVE_CONFIG_H");
     51  * see configure.ac for more details of the requirements.  The macro
     52  * "PNG_NO_CONFIG_H" is provided for maintainers to test for dependencies on
     53  * 'configure'; define this macro to prevent the configure build including the
     54  * configure generated config.h.  Libpng is expected to compile without *any*
     55  * special build system support on a reasonably ANSI-C compliant system.
     56  */
     57 #if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
     58 #  include <config.h>
     59 
     60    /* Pick up the definition of 'restrict' from config.h if it was read: */
     61 #  define PNG_RESTRICT restrict
     62 #endif
     63 
     64 /* To support symbol prefixing it is necessary to know *before* including png.h
     65  * whether the fixed point (and maybe other) APIs are exported, because if they
     66  * are not internal definitions may be required.  This is handled below just
     67  * before png.h is included, but load the configuration now if it is available.
     68  */
     69 #ifndef PNGLCONF_H
     70 #  include "pnglibconf.h"
     71 #endif
     72 
     73 /* Local renames may change non-exported API functions from png.h */
     74 #if defined(PNG_PREFIX) && !defined(PNGPREFIX_H)
     75 #  include "pngprefix.h"
     76 #endif
     77 
     78 #ifdef PNG_USER_CONFIG
     79 #  include "pngusr.h"
     80    /* These should have been defined in pngusr.h */
     81 #  ifndef PNG_USER_PRIVATEBUILD
     82 #    define PNG_USER_PRIVATEBUILD "Custom libpng build"
     83 #  endif
     84 #  ifndef PNG_USER_DLLFNAME_POSTFIX
     85 #    define PNG_USER_DLLFNAME_POSTFIX "Cb"
     86 #  endif
     87 #endif
     88 
     89 /* Compile time options.
     90  * =====================
     91  * In a multi-arch build the compiler may compile the code several times for the
     92  * same object module, producing different binaries for different architectures.
     93  * When this happens configure-time setting of the target host options cannot be
     94  * done and this interferes with the handling of the ARM NEON optimizations, and
     95  * possibly other similar optimizations.  Put additional tests here; in general
     96  * this is needed when the same option can be changed at both compile time and
     97  * run time depending on the target OS (i.e. iOS vs Android.)
     98  *
     99  * NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
    100  * this is not possible with certain compilers (Oracle SUN OS CC), as a result
    101  * it is necessary to ensure that all extern functions that *might* be used
    102  * regardless of $(CFLAGS) get declared in this file.  The test on __ARM_NEON__
    103  * below is one example of this behavior because it is controlled by the
    104  * presence or not of -mfpu=neon on the GCC command line, it is possible to do
    105  * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
    106  * do this.
    107  */
    108 #ifndef PNG_ARM_NEON_OPT
    109    /* ARM NEON optimizations are being controlled by the compiler settings,
    110     * typically the target FPU.  If the FPU has been set to NEON (-mfpu=neon
    111     * with GCC) then the compiler will define __ARM_NEON__ and we can rely
    112     * unconditionally on NEON instructions not crashing, otherwise we must
    113     * disable use of NEON instructions.
    114     *
    115     * NOTE: at present these optimizations depend on 'ALIGNED_MEMORY', so they
    116     * can only be turned on automatically if that is supported too.  If
    117     * PNG_ARM_NEON_OPT is set in CPPFLAGS (to >0) then arm/arm_init.c will fail
    118     * to compile with an appropriate #error if ALIGNED_MEMORY has been turned
    119     * off.
    120     *
    121     * Note that gcc-4.9 defines __ARM_NEON instead of the deprecated
    122     * __ARM_NEON__, so we check both variants.
    123     *
    124     * To disable ARM_NEON optimizations entirely, and skip compiling the
    125     * associated assembler code, pass --enable-arm-neon=no to configure
    126     * or put -DPNG_ARM_NEON_OPT=0 in CPPFLAGS.
    127     */
    128 #  if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
    129    defined(PNG_ALIGNED_MEMORY_SUPPORTED)
    130 #     define PNG_ARM_NEON_OPT 2
    131 #  else
    132 #     define PNG_ARM_NEON_OPT 0
    133 #  endif
    134 #endif
    135 
    136 #if PNG_ARM_NEON_OPT > 0
    137    /* NEON optimizations are to be at least considered by libpng, so enable the
    138     * callbacks to do this.
    139     */
    140 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
    141 
    142    /* By default the 'intrinsics' code in arm/filter_neon_intrinsics.c is used
    143     * if possible - if __ARM_NEON__ is set and the compiler version is not known
    144     * to be broken.  This is controlled by PNG_ARM_NEON_IMPLEMENTATION which can
    145     * be:
    146     *
    147     *    1  The intrinsics code (the default with __ARM_NEON__)
    148     *    2  The hand coded assembler (the default without __ARM_NEON__)
    149     *
    150     * It is possible to set PNG_ARM_NEON_IMPLEMENTATION in CPPFLAGS, however
    151     * this is *NOT* supported and may cease to work even after a minor revision
    152     * to libpng.  It *is* valid to do this for testing purposes, e.g. speed
    153     * testing or a new compiler, but the results should be communicated to the
    154     * libpng implementation list for incorporation in the next minor release.
    155     */
    156 #  ifndef PNG_ARM_NEON_IMPLEMENTATION
    157 #     if defined(__ARM_NEON__) || defined(__ARM_NEON)
    158 #        if defined(__clang__)
    159             /* At present it is unknown by the libpng developers which versions
    160              * of clang support the intrinsics, however some or perhaps all
    161              * versions do not work with the assembler so this may be
    162              * irrelevant, so just use the default (do nothing here.)
    163              */
    164 #        elif defined(__GNUC__)
    165             /* GCC 4.5.4 NEON support is known to be broken.  4.6.3 is known to
    166              * work, so if this *is* GCC, or G++, look for a version >4.5
    167              */
    168 #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
    169 #              define PNG_ARM_NEON_IMPLEMENTATION 2
    170 #           endif /* no GNUC support */
    171 #        endif /* __GNUC__ */
    172 #     else /* !defined __ARM_NEON__ */
    173          /* The 'intrinsics' code simply won't compile without this -mfpu=neon:
    174           */
    175 #        define PNG_ARM_NEON_IMPLEMENTATION 2
    176 #     endif /* __ARM_NEON__ */
    177 #  endif /* !PNG_ARM_NEON_IMPLEMENTATION */
    178 
    179 #  ifndef PNG_ARM_NEON_IMPLEMENTATION
    180       /* Use the intrinsics code by default. */
    181 #     define PNG_ARM_NEON_IMPLEMENTATION 1
    182 #  endif
    183 #endif /* PNG_ARM_NEON_OPT > 0 */
    184 
    185 #ifndef PNG_INTEL_SSE_OPT
    186 #   ifdef PNG_INTEL_SSE
    187       /* Only check for SSE if the build configuration has been modified to
    188        * enable SSE optimizations.  This means that these optimizations will
    189        * be off by default.  See contrib/intel for more details.
    190        */
    191 #     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
    192        defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
    193        (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
    194 #         define PNG_INTEL_SSE_OPT 1
    195 #      endif
    196 #   endif
    197 #endif
    198 
    199 #if PNG_INTEL_SSE_OPT > 0
    200 #   ifndef PNG_INTEL_SSE_IMPLEMENTATION
    201 #      if defined(__SSE4_1__) || defined(__AVX__)
    202           /* We are not actually using AVX, but checking for AVX is the best
    203              way we can detect SSE4.1 and SSSE3 on MSVC.
    204           */
    205 #         define PNG_INTEL_SSE_IMPLEMENTATION 3
    206 #      elif defined(__SSSE3__)
    207 #         define PNG_INTEL_SSE_IMPLEMENTATION 2
    208 #      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
    209        (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
    210 #         define PNG_INTEL_SSE_IMPLEMENTATION 1
    211 #      else
    212 #         define PNG_INTEL_SSE_IMPLEMENTATION 0
    213 #      endif
    214 #   endif
    215 
    216 #   if PNG_INTEL_SSE_IMPLEMENTATION > 0
    217 #      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
    218 #   endif
    219 #endif
    220 
    221 /* Is this a build of a DLL where compilation of the object modules requires
    222  * different preprocessor settings to those required for a simple library?  If
    223  * so PNG_BUILD_DLL must be set.
    224  *
    225  * If libpng is used inside a DLL but that DLL does not export the libpng APIs
    226  * PNG_BUILD_DLL must not be set.  To avoid the code below kicking in build a
    227  * static library of libpng then link the DLL against that.
    228  */
    229 #ifndef PNG_BUILD_DLL
    230 #  ifdef DLL_EXPORT
    231       /* This is set by libtool when files are compiled for a DLL; libtool
    232        * always compiles twice, even on systems where it isn't necessary.  Set
    233        * PNG_BUILD_DLL in case it is necessary:
    234        */
    235 #     define PNG_BUILD_DLL
    236 #  else
    237 #     ifdef _WINDLL
    238          /* This is set by the Microsoft Visual Studio IDE in projects that
    239           * build a DLL.  It can't easily be removed from those projects (it
    240           * isn't visible in the Visual Studio UI) so it is a fairly reliable
    241           * indication that PNG_IMPEXP needs to be set to the DLL export
    242           * attributes.
    243           */
    244 #        define PNG_BUILD_DLL
    245 #     else
    246 #        ifdef __DLL__
    247             /* This is set by the Borland C system when compiling for a DLL
    248              * (as above.)
    249              */
    250 #           define PNG_BUILD_DLL
    251 #        else
    252             /* Add additional compiler cases here. */
    253 #        endif
    254 #     endif
    255 #  endif
    256 #endif /* Setting PNG_BUILD_DLL if required */
    257 
    258 /* See pngconf.h for more details: the builder of the library may set this on
    259  * the command line to the right thing for the specific compilation system or it
    260  * may be automagically set above (at present we know of no system where it does
    261  * need to be set on the command line.)
    262  *
    263  * PNG_IMPEXP must be set here when building the library to prevent pngconf.h
    264  * setting it to the "import" setting for a DLL build.
    265  */
    266 #ifndef PNG_IMPEXP
    267 #  ifdef PNG_BUILD_DLL
    268 #     define PNG_IMPEXP PNG_DLL_EXPORT
    269 #  else
    270       /* Not building a DLL, or the DLL doesn't require specific export
    271        * definitions.
    272        */
    273 #     define PNG_IMPEXP
    274 #  endif
    275 #endif
    276 
    277 /* No warnings for private or deprecated functions in the build: */
    278 #ifndef PNG_DEPRECATED
    279 #  define PNG_DEPRECATED
    280 #endif
    281 #ifndef PNG_PRIVATE
    282 #  define PNG_PRIVATE
    283 #endif
    284 
    285 /* Symbol preprocessing support.
    286  *
    287  * To enable listing global, but internal, symbols the following macros should
    288  * always be used to declare an extern data or function object in this file.
    289  */
    290 #ifndef PNG_INTERNAL_DATA
    291 #  define PNG_INTERNAL_DATA(type, name, array) PNG_LINKAGE_DATA type name array
    292 #endif
    293 
    294 #ifndef PNG_INTERNAL_FUNCTION
    295 #  define PNG_INTERNAL_FUNCTION(type, name, args, attributes)\
    296       PNG_LINKAGE_FUNCTION PNG_FUNCTION(type, name, args, PNG_EMPTY attributes)
    297 #endif
    298 
    299 #ifndef PNG_INTERNAL_CALLBACK
    300 #  define PNG_INTERNAL_CALLBACK(type, name, args, attributes)\
    301       PNG_LINKAGE_CALLBACK PNG_FUNCTION(type, (PNGCBAPI name), args,\
    302          PNG_EMPTY attributes)
    303 #endif
    304 
    305 /* If floating or fixed point APIs are disabled they may still be compiled
    306  * internally.  To handle this make sure they are declared as the appropriate
    307  * internal extern function (otherwise the symbol prefixing stuff won't work and
    308  * the functions will be used without definitions.)
    309  *
    310  * NOTE: although all the API functions are declared here they are not all
    311  * actually built!  Because the declarations are still made it is necessary to
    312  * fake out types that they depend on.
    313  */
    314 #ifndef PNG_FP_EXPORT
    315 #  ifndef PNG_FLOATING_POINT_SUPPORTED
    316 #     define PNG_FP_EXPORT(ordinal, type, name, args)\
    317          PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
    318 #     ifndef PNG_VERSION_INFO_ONLY
    319          typedef struct png_incomplete png_double;
    320          typedef png_double*           png_doublep;
    321          typedef const png_double*     png_const_doublep;
    322          typedef png_double**          png_doublepp;
    323 #     endif
    324 #  endif
    325 #endif
    326 #ifndef PNG_FIXED_EXPORT
    327 #  ifndef PNG_FIXED_POINT_SUPPORTED
    328 #     define PNG_FIXED_EXPORT(ordinal, type, name, args)\
    329          PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
    330 #  endif
    331 #endif
    332 
    333 #include "png.h"
    334 
    335 /* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
    336 #ifndef PNG_DLL_EXPORT
    337 #  define PNG_DLL_EXPORT
    338 #endif
    339 
    340 /* This is a global switch to set the compilation for an installed system
    341  * (a release build).  It can be set for testing debug builds to ensure that
    342  * they will compile when the build type is switched to RC or STABLE, the
    343  * default is just to use PNG_LIBPNG_BUILD_BASE_TYPE.  Set this in CPPFLAGS
    344  * with either:
    345  *
    346  *   -DPNG_RELEASE_BUILD Turns on the release compile path
    347  *   -DPNG_RELEASE_BUILD=0 Turns it off
    348  * or in your pngusr.h with
    349  *   #define PNG_RELEASE_BUILD=1 Turns on the release compile path
    350  *   #define PNG_RELEASE_BUILD=0 Turns it off
    351  */
    352 #ifndef PNG_RELEASE_BUILD
    353 #  define PNG_RELEASE_BUILD (PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC)
    354 #endif
    355 
    356 /* SECURITY and SAFETY:
    357  *
    358  * libpng is built with support for internal limits on image dimensions and
    359  * memory usage.  These are documented in scripts/pnglibconf.dfa of the
    360  * source and recorded in the machine generated header file pnglibconf.h.
    361  */
    362 
    363 /* If you are running on a machine where you cannot allocate more
    364  * than 64K of memory at once, uncomment this.  While libpng will not
    365  * normally need that much memory in a chunk (unless you load up a very
    366  * large file), zlib needs to know how big of a chunk it can use, and
    367  * libpng thus makes sure to check any memory allocation to verify it
    368  * will fit into memory.
    369  *
    370  * zlib provides 'MAXSEG_64K' which, if defined, indicates the
    371  * same limit and pngconf.h (already included) sets the limit
    372  * if certain operating systems are detected.
    373  */
    374 #if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
    375 #  define PNG_MAX_MALLOC_64K
    376 #endif
    377 
    378 #ifndef PNG_UNUSED
    379 /* Unused formal parameter warnings are silenced using the following macro
    380  * which is expected to have no bad effects on performance (optimizing
    381  * compilers will probably remove it entirely).  Note that if you replace
    382  * it with something other than whitespace, you must include the terminating
    383  * semicolon.
    384  */
    385 #  define PNG_UNUSED(param) (void)param;
    386 #endif
    387 
    388 /* Just a little check that someone hasn't tried to define something
    389  * contradictory.
    390  */
    391 #if (PNG_ZBUF_SIZE > 65536L) && defined(PNG_MAX_MALLOC_64K)
    392 #  undef PNG_ZBUF_SIZE
    393 #  define PNG_ZBUF_SIZE 65536L
    394 #endif
    395 
    396 /* If warnings or errors are turned off the code is disabled or redirected here.
    397  * From 1.5.4 functions have been added to allow very limited formatting of
    398  * error and warning messages - this code will also be disabled here.
    399  */
    400 #ifdef PNG_WARNINGS_SUPPORTED
    401 #  define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
    402 #else
    403 #  define png_warning_parameter(p,number,string) ((void)0)
    404 #  define png_warning_parameter_unsigned(p,number,format,value) ((void)0)
    405 #  define png_warning_parameter_signed(p,number,format,value) ((void)0)
    406 #  define png_formatted_warning(pp,p,message) ((void)(pp))
    407 #  define PNG_WARNING_PARAMETERS(p)
    408 #endif
    409 #ifndef PNG_ERROR_TEXT_SUPPORTED
    410 #  define png_fixed_error(s1,s2) png_err(s1)
    411 #endif
    412 
    413 /* C allows up-casts from (void*) to any pointer and (const void*) to any
    414  * pointer to a const object.  C++ regards this as a type error and requires an
    415  * explicit, static, cast and provides the static_cast<> rune to ensure that
    416  * const is not cast away.
    417  */
    418 #ifdef __cplusplus
    419 #  define png_voidcast(type, value) static_cast<type>(value)
    420 #  define png_constcast(type, value) const_cast<type>(value)
    421 #  define png_aligncast(type, value) \
    422    static_cast<type>(static_cast<void*>(value))
    423 #  define png_aligncastconst(type, value) \
    424    static_cast<type>(static_cast<const void*>(value))
    425 #else
    426 #  define png_voidcast(type, value) (value)
    427 #  define png_constcast(type, value) ((type)(value))
    428 #  define png_aligncast(type, value) ((void*)(value))
    429 #  define png_aligncastconst(type, value) ((const void*)(value))
    430 #endif /* __cplusplus */
    431 
    432 /* Some fixed point APIs are still required even if not exported because
    433  * they get used by the corresponding floating point APIs.  This magic
    434  * deals with this:
    435  */
    436 #ifdef PNG_FIXED_POINT_SUPPORTED
    437 #  define PNGFAPI PNGAPI
    438 #else
    439 #  define PNGFAPI /* PRIVATE */
    440 #endif
    441 
    442 #ifndef PNG_VERSION_INFO_ONLY
    443 /* Other defines specific to compilers can go here.  Try to keep
    444  * them inside an appropriate ifdef/endif pair for portability.
    445  */
    446 #if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
    447     defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
    448    /* png.c requires the following ANSI-C constants if the conversion of
    449     * floating point to ASCII is implemented therein:
    450     *
    451     *  DBL_DIG  Maximum number of decimal digits (can be set to any constant)
    452     *  DBL_MIN  Smallest normalized fp number (can be set to an arbitrary value)
    453     *  DBL_MAX  Maximum floating point number (can be set to an arbitrary value)
    454     */
    455 #  include <float.h>
    456 
    457 #  if (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
    458     defined(THINK_C) || defined(__SC__) || defined(TARGET_OS_MAC)
    459      /* We need to check that <math.h> hasn't already been included earlier
    460       * as it seems it doesn't agree with <fp.h>, yet we should really use
    461       * <fp.h> if possible.
    462       */
    463 #    if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
    464 #      include <fp.h>
    465 #    endif
    466 #  else
    467 #    include <math.h>
    468 #  endif
    469 #  if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
    470      /* Amiga SAS/C: We must include builtin FPU functions when compiling using
    471       * MATH=68881
    472       */
    473 #    include <m68881.h>
    474 #  endif
    475 #endif
    476 
    477 /* This provides the non-ANSI (far) memory allocation routines. */
    478 #if defined(__TURBOC__) && defined(__MSDOS__)
    479 #  include <mem.h>
    480 #  include <alloc.h>
    481 #endif
    482 
    483 #if defined(WIN32) || defined(_Windows) || defined(_WINDOWS) || \
    484     defined(_WIN32) || defined(__WIN32__)
    485 #  include <windows.h>  /* defines _WINDOWS_ macro */
    486 #endif
    487 #endif /* PNG_VERSION_INFO_ONLY */
    488 
    489 /* Moved here around 1.5.0beta36 from pngconf.h */
    490 /* Users may want to use these so they are not private.  Any library
    491  * functions that are passed far data must be model-independent.
    492  */
    493 
    494 /* Memory model/platform independent fns */
    495 #ifndef PNG_ABORT
    496 #  ifdef _WINDOWS_
    497 #    define PNG_ABORT() ExitProcess(0)
    498 #  else
    499 #    define PNG_ABORT() abort()
    500 #  endif
    501 #endif
    502 
    503 /* These macros may need to be architecture dependent. */
    504 #define PNG_ALIGN_NONE   0 /* do not use data alignment */
    505 #define PNG_ALIGN_ALWAYS 1 /* assume unaligned accesses are OK */
    506 #ifdef offsetof
    507 #  define PNG_ALIGN_OFFSET 2 /* use offsetof to determine alignment */
    508 #else
    509 #  define PNG_ALIGN_OFFSET -1 /* prevent the use of this */
    510 #endif
    511 #define PNG_ALIGN_SIZE   3 /* use sizeof to determine alignment */
    512 
    513 #ifndef PNG_ALIGN_TYPE
    514    /* Default to using aligned access optimizations and requiring alignment to a
    515     * multiple of the data type size.  Override in a compiler specific fashion
    516     * if necessary by inserting tests here:
    517     */
    518 #  define PNG_ALIGN_TYPE PNG_ALIGN_SIZE
    519 #endif
    520 
    521 #if PNG_ALIGN_TYPE == PNG_ALIGN_SIZE
    522    /* This is used because in some compiler implementations non-aligned
    523     * structure members are supported, so the offsetof approach below fails.
    524     * Set PNG_ALIGN_SIZE=0 for compiler combinations where unaligned access
    525     * is good for performance.  Do not do this unless you have tested the result
    526     * and understand it.
    527     */
    528 #  define png_alignof(type) (sizeof (type))
    529 #else
    530 #  if PNG_ALIGN_TYPE == PNG_ALIGN_OFFSET
    531 #     define png_alignof(type) offsetof(struct{char c; type t;}, t)
    532 #  else
    533 #     if PNG_ALIGN_TYPE == PNG_ALIGN_ALWAYS
    534 #        define png_alignof(type) (1)
    535 #     endif
    536       /* Else leave png_alignof undefined to prevent use thereof */
    537 #  endif
    538 #endif
    539 
    540 /* This implicitly assumes alignment is always to a power of 2. */
    541 #ifdef png_alignof
    542 #  define png_isaligned(ptr, type)\
    543    ((((const char*)ptr-(const char*)0) & (png_alignof(type)-1)) == 0)
    544 #else
    545 #  define png_isaligned(ptr, type) 0
    546 #endif
    547 
    548 /* End of memory model/platform independent support */
    549 /* End of 1.5.0beta36 move from pngconf.h */
    550 
    551 /* CONSTANTS and UTILITY MACROS
    552  * These are used internally by libpng and not exposed in the API
    553  */
    554 
    555 /* Various modes of operation.  Note that after an init, mode is set to
    556  * zero automatically when the structure is created.  Three of these
    557  * are defined in png.h because they need to be visible to applications
    558  * that call png_set_unknown_chunk().
    559  */
    560 /* #define PNG_HAVE_IHDR            0x01 (defined in png.h) */
    561 /* #define PNG_HAVE_PLTE            0x02 (defined in png.h) */
    562 #define PNG_HAVE_IDAT               0x04
    563 /* #define PNG_AFTER_IDAT           0x08 (defined in png.h) */
    564 #define PNG_HAVE_IEND               0x10
    565                    /*               0x20 (unused) */
    566                    /*               0x40 (unused) */
    567                    /*               0x80 (unused) */
    568 #define PNG_HAVE_CHUNK_HEADER      0x100
    569 #define PNG_WROTE_tIME             0x200
    570 #define PNG_WROTE_INFO_BEFORE_PLTE 0x400
    571 #define PNG_BACKGROUND_IS_GRAY     0x800
    572 #define PNG_HAVE_PNG_SIGNATURE    0x1000
    573 #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
    574                    /*             0x4000 (unused) */
    575 #define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */
    576 
    577 /* Flags for the transformations the PNG library does on the image data */
    578 #define PNG_BGR                 0x0001
    579 #define PNG_INTERLACE           0x0002
    580 #define PNG_PACK                0x0004
    581 #define PNG_SHIFT               0x0008
    582 #define PNG_SWAP_BYTES          0x0010
    583 #define PNG_INVERT_MONO         0x0020
    584 #define PNG_QUANTIZE            0x0040
    585 #define PNG_COMPOSE             0x0080     /* Was PNG_BACKGROUND */
    586 #define PNG_BACKGROUND_EXPAND   0x0100
    587 #define PNG_EXPAND_16           0x0200     /* Added to libpng 1.5.2 */
    588 #define PNG_16_TO_8             0x0400     /* Becomes 'chop' in 1.5.4 */
    589 #define PNG_RGBA                0x0800
    590 #define PNG_EXPAND              0x1000
    591 #define PNG_GAMMA               0x2000
    592 #define PNG_GRAY_TO_RGB         0x4000
    593 #define PNG_FILLER              0x8000
    594 #define PNG_PACKSWAP           0x10000
    595 #define PNG_SWAP_ALPHA         0x20000
    596 #define PNG_STRIP_ALPHA        0x40000
    597 #define PNG_INVERT_ALPHA       0x80000
    598 #define PNG_USER_TRANSFORM    0x100000
    599 #define PNG_RGB_TO_GRAY_ERR   0x200000
    600 #define PNG_RGB_TO_GRAY_WARN  0x400000
    601 #define PNG_RGB_TO_GRAY       0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
    602 #define PNG_ENCODE_ALPHA      0x800000 /* Added to libpng-1.5.4 */
    603 #define PNG_ADD_ALPHA        0x1000000 /* Added to libpng-1.2.7 */
    604 #define PNG_EXPAND_tRNS      0x2000000 /* Added to libpng-1.2.9 */
    605 #define PNG_SCALE_16_TO_8    0x4000000 /* Added to libpng-1.5.4 */
    606                        /*    0x8000000 unused */
    607                        /*   0x10000000 unused */
    608                        /*   0x20000000 unused */
    609                        /*   0x40000000 unused */
    610 /* Flags for png_create_struct */
    611 #define PNG_STRUCT_PNG   0x0001
    612 #define PNG_STRUCT_INFO  0x0002
    613 
    614 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
    615 #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
    616 #define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002 /* Added to libpng-1.6.0 */
    617                                   /*      0x0004    unused */
    618 #define PNG_FLAG_ZSTREAM_ENDED            0x0008 /* Added to libpng-1.6.0 */
    619                                   /*      0x0010    unused */
    620                                   /*      0x0020    unused */
    621 #define PNG_FLAG_ROW_INIT                 0x0040
    622 #define PNG_FLAG_FILLER_AFTER             0x0080
    623 #define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
    624 #define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
    625 #define PNG_FLAG_CRC_CRITICAL_USE         0x0400
    626 #define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
    627 #define PNG_FLAG_ASSUME_sRGB              0x1000 /* Added to libpng-1.5.4 */
    628 #define PNG_FLAG_OPTIMIZE_ALPHA           0x2000 /* Added to libpng-1.5.4 */
    629 #define PNG_FLAG_DETECT_UNINITIALIZED     0x4000 /* Added to libpng-1.5.4 */
    630 /* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000 */
    631 /* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000 */
    632 #define PNG_FLAG_LIBRARY_MISMATCH        0x20000
    633 #define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000
    634 #define PNG_FLAG_STRIP_ERROR_TEXT        0x80000
    635 #define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000 /* Added to libpng-1.4.0 */
    636 #define PNG_FLAG_APP_WARNINGS_WARN      0x200000 /* Added to libpng-1.6.0 */
    637 #define PNG_FLAG_APP_ERRORS_WARN        0x400000 /* Added to libpng-1.6.0 */
    638                                   /*    0x800000    unused */
    639                                   /*   0x1000000    unused */
    640                                   /*   0x2000000    unused */
    641                                   /*   0x4000000    unused */
    642                                   /*   0x8000000    unused */
    643                                   /*  0x10000000    unused */
    644                                   /*  0x20000000    unused */
    645                                   /*  0x40000000    unused */
    646 
    647 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
    648                                      PNG_FLAG_CRC_ANCILLARY_NOWARN)
    649 
    650 #define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
    651                                      PNG_FLAG_CRC_CRITICAL_IGNORE)
    652 
    653 #define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
    654                                      PNG_FLAG_CRC_CRITICAL_MASK)
    655 
    656 /* Save typing and make code easier to understand */
    657 
    658 #define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
    659    abs((int)((c1).green) - (int)((c2).green)) + \
    660    abs((int)((c1).blue) - (int)((c2).blue)))
    661 
    662 /* Added to libpng-1.6.0: scale a 16-bit value in the range 0..65535 to 0..255
    663  * by dividing by 257 *with rounding*.  This macro is exact for the given range.
    664  * See the discourse in pngrtran.c png_do_scale_16_to_8.  The values in the
    665  * macro were established by experiment (modifying the added value).  The macro
    666  * has a second variant that takes a value already scaled by 255 and divides by
    667  * 65535 - this has a maximum error of .502.  Over the range 0..65535*65535 it
    668  * only gives off-by-one errors and only for 0.5% (1 in 200) of the values.
    669  */
    670 #define PNG_DIV65535(v24) (((v24) + 32895) >> 16)
    671 #define PNG_DIV257(v16) PNG_DIV65535((png_uint_32)(v16) * 255)
    672 
    673 /* Added to libpng-1.2.6 JB */
    674 #define PNG_ROWBYTES(pixel_bits, width) \
    675     ((pixel_bits) >= 8 ? \
    676     ((png_size_t)(width) * (((png_size_t)(pixel_bits)) >> 3)) : \
    677     (( ((png_size_t)(width) * ((png_size_t)(pixel_bits))) + 7) >> 3) )
    678 
    679 /* PNG_OUT_OF_RANGE returns true if value is outside the range
    680  * ideal-delta..ideal+delta.  Each argument is evaluated twice.
    681  * "ideal" and "delta" should be constants, normally simple
    682  * integers, "value" a variable. Added to libpng-1.2.6 JB
    683  */
    684 #define PNG_OUT_OF_RANGE(value, ideal, delta) \
    685    ( (value) < (ideal)-(delta) || (value) > (ideal)+(delta) )
    686 
    687 /* Conversions between fixed and floating point, only defined if
    688  * required (to make sure the code doesn't accidentally use float
    689  * when it is supposedly disabled.)
    690  */
    691 #ifdef PNG_FLOATING_POINT_SUPPORTED
    692 /* The floating point conversion can't overflow, though it can and
    693  * does lose accuracy relative to the original fixed point value.
    694  * In practice this doesn't matter because png_fixed_point only
    695  * stores numbers with very low precision.  The png_ptr and s
    696  * arguments are unused by default but are there in case error
    697  * checking becomes a requirement.
    698  */
    699 #define png_float(png_ptr, fixed, s) (.00001 * (fixed))
    700 
    701 /* The fixed point conversion performs range checking and evaluates
    702  * its argument multiple times, so must be used with care.  The
    703  * range checking uses the PNG specification values for a signed
    704  * 32-bit fixed point value except that the values are deliberately
    705  * rounded-to-zero to an integral value - 21474 (21474.83 is roughly
    706  * (2^31-1) * 100000). 's' is a string that describes the value being
    707  * converted.
    708  *
    709  * NOTE: this macro will raise a png_error if the range check fails,
    710  * therefore it is normally only appropriate to use this on values
    711  * that come from API calls or other sources where an out of range
    712  * error indicates a programming error, not a data error!
    713  *
    714  * NOTE: by default this is off - the macro is not used - because the
    715  * function call saves a lot of code.
    716  */
    717 #ifdef PNG_FIXED_POINT_MACRO_SUPPORTED
    718 #define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
    719     ((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
    720 #endif
    721 /* else the corresponding function is defined below, inside the scope of the
    722  * cplusplus test.
    723  */
    724 #endif
    725 
    726 /* Constants for known chunk types.  If you need to add a chunk, define the name
    727  * here.  For historical reasons these constants have the form png_<name>; i.e.
    728  * the prefix is lower case.  Please use decimal values as the parameters to
    729  * match the ISO PNG specification and to avoid relying on the C locale
    730  * interpretation of character values.
    731  *
    732  * Prior to 1.5.6 these constants were strings, as of 1.5.6 png_uint_32 values
    733  * are computed and a new macro (PNG_STRING_FROM_CHUNK) added to allow a string
    734  * to be generated if required.
    735  *
    736  * PNG_32b correctly produces a value shifted by up to 24 bits, even on
    737  * architectures where (int) is only 16 bits.
    738  */
    739 #define PNG_32b(b,s) ((png_uint_32)(b) << (s))
    740 #define PNG_U32(b1,b2,b3,b4) \
    741    (PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0))
    742 
    743 /* Constants for known chunk types.
    744  *
    745  * MAINTAINERS: If you need to add a chunk, define the name here.
    746  * For historical reasons these constants have the form png_<name>; i.e.
    747  * the prefix is lower case.  Please use decimal values as the parameters to
    748  * match the ISO PNG specification and to avoid relying on the C locale
    749  * interpretation of character values.  Please keep the list sorted.
    750  *
    751  * Notice that PNG_U32 is used to define a 32-bit value for the 4 byte chunk
    752  * type.  In fact the specification does not express chunk types this way,
    753  * however using a 32-bit value means that the chunk type can be read from the
    754  * stream using exactly the same code as used for a 32-bit unsigned value and
    755  * can be examined far more efficiently (using one arithmetic compare).
    756  *
    757  * Prior to 1.5.6 the chunk type constants were expressed as C strings.  The
    758  * libpng API still uses strings for 'unknown' chunks and a macro,
    759  * PNG_STRING_FROM_CHUNK, allows a string to be generated if required.  Notice
    760  * that for portable code numeric values must still be used; the string "IHDR"
    761  * is not portable and neither is PNG_U32('I', 'H', 'D', 'R').
    762  *
    763  * In 1.7.0 the definitions will be made public in png.h to avoid having to
    764  * duplicate the same definitions in application code.
    765  */
    766 #define png_IDAT PNG_U32( 73,  68,  65,  84)
    767 #define png_IEND PNG_U32( 73,  69,  78,  68)
    768 #define png_IHDR PNG_U32( 73,  72,  68,  82)
    769 #define png_PLTE PNG_U32( 80,  76,  84,  69)
    770 #define png_bKGD PNG_U32( 98,  75,  71,  68)
    771 #define png_cHRM PNG_U32( 99,  72,  82,  77)
    772 #define png_fRAc PNG_U32(102,  82,  65,  99) /* registered, not defined */
    773 #define png_gAMA PNG_U32(103,  65,  77,  65)
    774 #define png_gIFg PNG_U32(103,  73,  70, 103)
    775 #define png_gIFt PNG_U32(103,  73,  70, 116) /* deprecated */
    776 #define png_gIFx PNG_U32(103,  73,  70, 120)
    777 #define png_hIST PNG_U32(104,  73,  83,  84)
    778 #define png_iCCP PNG_U32(105,  67,  67,  80)
    779 #define png_iTXt PNG_U32(105,  84,  88, 116)
    780 #define png_oFFs PNG_U32(111,  70,  70, 115)
    781 #define png_pCAL PNG_U32(112,  67,  65,  76)
    782 #define png_pHYs PNG_U32(112,  72,  89, 115)
    783 #define png_sBIT PNG_U32(115,  66,  73,  84)
    784 #define png_sCAL PNG_U32(115,  67,  65,  76)
    785 #define png_sPLT PNG_U32(115,  80,  76,  84)
    786 #define png_sRGB PNG_U32(115,  82,  71,  66)
    787 #define png_sTER PNG_U32(115,  84,  69,  82)
    788 #define png_tEXt PNG_U32(116,  69,  88, 116)
    789 #define png_tIME PNG_U32(116,  73,  77,  69)
    790 #define png_tRNS PNG_U32(116,  82,  78,  83)
    791 #define png_zTXt PNG_U32(122,  84,  88, 116)
    792 
    793 /* The following will work on (signed char*) strings, whereas the get_uint_32
    794  * macro will fail on top-bit-set values because of the sign extension.
    795  */
    796 #define PNG_CHUNK_FROM_STRING(s)\
    797    PNG_U32(0xff & (s)[0], 0xff & (s)[1], 0xff & (s)[2], 0xff & (s)[3])
    798 
    799 /* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
    800  * signed and the argument is a (char[])  This macro will fail miserably on
    801  * systems where (char) is more than 8 bits.
    802  */
    803 #define PNG_STRING_FROM_CHUNK(s,c)\
    804    (void)(((char*)(s))[0]=(char)(((c)>>24) & 0xff), \
    805    ((char*)(s))[1]=(char)(((c)>>16) & 0xff),\
    806    ((char*)(s))[2]=(char)(((c)>>8) & 0xff), \
    807    ((char*)(s))[3]=(char)((c & 0xff)))
    808 
    809 /* Do the same but terminate with a null character. */
    810 #define PNG_CSTRING_FROM_CHUNK(s,c)\
    811    (void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)
    812 
    813 /* Test on flag values as defined in the spec (section 5.4): */
    814 #define PNG_CHUNK_ANCILLARY(c)   (1 & ((c) >> 29))
    815 #define PNG_CHUNK_CRITICAL(c)     (!PNG_CHUNK_ANCILLARY(c))
    816 #define PNG_CHUNK_PRIVATE(c)      (1 & ((c) >> 21))
    817 #define PNG_CHUNK_RESERVED(c)     (1 & ((c) >> 13))
    818 #define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >>  5))
    819 
    820 /* Gamma values (new at libpng-1.5.4): */
    821 #define PNG_GAMMA_MAC_OLD 151724  /* Assume '1.8' is really 2.2/1.45! */
    822 #define PNG_GAMMA_MAC_INVERSE 65909
    823 #define PNG_GAMMA_sRGB_INVERSE 45455
    824 
    825 /* Almost everything below is C specific; the #defines above can be used in
    826  * non-C code (so long as it is C-preprocessed) the rest of this stuff cannot.
    827  */
    828 #ifndef PNG_VERSION_INFO_ONLY
    829 
    830 #include "pngstruct.h"
    831 #include "pnginfo.h"
    832 
    833 /* Validate the include paths - the include path used to generate pnglibconf.h
    834  * must match that used in the build, or we must be using pnglibconf.h.prebuilt:
    835  */
    836 #if PNG_ZLIB_VERNUM != 0 && PNG_ZLIB_VERNUM != ZLIB_VERNUM
    837 #  error ZLIB_VERNUM != PNG_ZLIB_VERNUM \
    838       "-I (include path) error: see the notes in pngpriv.h"
    839    /* This means that when pnglibconf.h was built the copy of zlib.h that it
    840     * used is not the same as the one being used here.  Because the build of
    841     * libpng makes decisions to use inflateInit2 and inflateReset2 based on the
    842     * zlib version number and because this affects handling of certain broken
    843     * PNG files the -I directives must match.
    844     *
    845     * The most likely explanation is that you passed a -I in CFLAGS. This will
    846     * not work; all the preprocessor directories and in particular all the -I
    847     * directives must be in CPPFLAGS.
    848     */
    849 #endif
    850 
    851 /* This is used for 16-bit gamma tables -- only the top level pointers are
    852  * const; this could be changed:
    853  */
    854 typedef const png_uint_16p * png_const_uint_16pp;
    855 
    856 /* Added to libpng-1.5.7: sRGB conversion tables */
    857 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
    858    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
    859 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
    860 PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_table, [256]);
    861    /* Convert from an sRGB encoded value 0..255 to a 16-bit linear value,
    862     * 0..65535.  This table gives the closest 16-bit answers (no errors).
    863     */
    864 #endif
    865 
    866 PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_base, [512]);
    867 PNG_INTERNAL_DATA(const png_byte, png_sRGB_delta, [512]);
    868 
    869 #define PNG_sRGB_FROM_LINEAR(linear) \
    870   ((png_byte)(0xff & ((png_sRGB_base[(linear)>>15] \
    871    + ((((linear) & 0x7fff)*png_sRGB_delta[(linear)>>15])>>12)) >> 8)))
    872    /* Given a value 'linear' in the range 0..255*65535 calculate the 8-bit sRGB
    873     * encoded value with maximum error 0.646365.  Note that the input is not a
    874     * 16-bit value; it has been multiplied by 255! */
    875 #endif /* SIMPLIFIED_READ/WRITE */
    876 
    877 
    878 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
    879 #ifdef __cplusplus
    880 extern "C" {
    881 #endif /* __cplusplus */
    882 
    883 /* Internal functions; these are not exported from a DLL however because they
    884  * are used within several of the C source files they have to be C extern.
    885  *
    886  * All of these functions must be declared with PNG_INTERNAL_FUNCTION.
    887  */
    888 
    889 /* Zlib support */
    890 #define PNG_UNEXPECTED_ZLIB_RETURN (-7)
    891 PNG_INTERNAL_FUNCTION(void, png_zstream_error,(png_structrp png_ptr, int ret),
    892    PNG_EMPTY);
    893    /* Used by the zlib handling functions to ensure that z_stream::msg is always
    894     * set before they return.
    895     */
    896 
    897 #ifdef PNG_WRITE_SUPPORTED
    898 PNG_INTERNAL_FUNCTION(void,png_free_buffer_list,(png_structrp png_ptr,
    899    png_compression_bufferp *list),PNG_EMPTY);
    900    /* Free the buffer list used by the compressed write code. */
    901 #endif
    902 
    903 #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
    904    !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
    905    (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
    906    defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
    907    defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
    908    (defined(PNG_sCAL_SUPPORTED) && \
    909    defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
    910 PNG_INTERNAL_FUNCTION(png_fixed_point,png_fixed,(png_const_structrp png_ptr,
    911    double fp, png_const_charp text),PNG_EMPTY);
    912 #endif
    913 
    914 /* Check the user version string for compatibility, returns false if the version
    915  * numbers aren't compatible.
    916  */
    917 PNG_INTERNAL_FUNCTION(int,png_user_version_check,(png_structrp png_ptr,
    918    png_const_charp user_png_ver),PNG_EMPTY);
    919 
    920 /* Internal base allocator - no messages, NULL on failure to allocate.  This
    921  * does, however, call the application provided allocator and that could call
    922  * png_error (although that would be a bug in the application implementation.)
    923  */
    924 PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_base,(png_const_structrp png_ptr,
    925    png_alloc_size_t size),PNG_ALLOCATED);
    926 
    927 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
    928    defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
    929 /* Internal array allocator, outputs no error or warning messages on failure,
    930  * just returns NULL.
    931  */
    932 PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_array,(png_const_structrp png_ptr,
    933    int nelements, size_t element_size),PNG_ALLOCATED);
    934 
    935 /* The same but an existing array is extended by add_elements.  This function
    936  * also memsets the new elements to 0 and copies the old elements.  The old
    937  * array is not freed or altered.
    938  */
    939 PNG_INTERNAL_FUNCTION(png_voidp,png_realloc_array,(png_const_structrp png_ptr,
    940    png_const_voidp array, int old_elements, int add_elements,
    941    size_t element_size),PNG_ALLOCATED);
    942 #endif /* text, sPLT or unknown chunks */
    943 
    944 /* Magic to create a struct when there is no struct to call the user supplied
    945  * memory allocators.  Because error handling has not been set up the memory
    946  * handlers can't safely call png_error, but this is an obscure and undocumented
    947  * restriction so libpng has to assume that the 'free' handler, at least, might
    948  * call png_error.
    949  */
    950 PNG_INTERNAL_FUNCTION(png_structp,png_create_png_struct,
    951    (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
    952     png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn,
    953     png_free_ptr free_fn),PNG_ALLOCATED);
    954 
    955 /* Free memory from internal libpng struct */
    956 PNG_INTERNAL_FUNCTION(void,png_destroy_png_struct,(png_structrp png_ptr),
    957    PNG_EMPTY);
    958 
    959 /* Free an allocated jmp_buf (always succeeds) */
    960 PNG_INTERNAL_FUNCTION(void,png_free_jmpbuf,(png_structrp png_ptr),PNG_EMPTY);
    961 
    962 /* Function to allocate memory for zlib.  PNGAPI is disallowed. */
    963 PNG_INTERNAL_FUNCTION(voidpf,png_zalloc,(voidpf png_ptr, uInt items, uInt size),
    964    PNG_ALLOCATED);
    965 
    966 /* Function to free memory for zlib.  PNGAPI is disallowed. */
    967 PNG_INTERNAL_FUNCTION(void,png_zfree,(voidpf png_ptr, voidpf ptr),PNG_EMPTY);
    968 
    969 /* Next four functions are used internally as callbacks.  PNGCBAPI is required
    970  * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3, changed to
    971  * PNGCBAPI at 1.5.0
    972  */
    973 
    974 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_read_data,(png_structp png_ptr,
    975     png_bytep data, png_size_t length),PNG_EMPTY);
    976 
    977 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    978 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_push_fill_buffer,(png_structp png_ptr,
    979     png_bytep buffer, png_size_t length),PNG_EMPTY);
    980 #endif
    981 
    982 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_write_data,(png_structp png_ptr,
    983     png_bytep data, png_size_t length),PNG_EMPTY);
    984 
    985 #ifdef PNG_WRITE_FLUSH_SUPPORTED
    986 #  ifdef PNG_STDIO_SUPPORTED
    987 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_flush,(png_structp png_ptr),
    988    PNG_EMPTY);
    989 #  endif
    990 #endif
    991 
    992 /* Reset the CRC variable */
    993 PNG_INTERNAL_FUNCTION(void,png_reset_crc,(png_structrp png_ptr),PNG_EMPTY);
    994 
    995 /* Write the "data" buffer to whatever output you are using */
    996 PNG_INTERNAL_FUNCTION(void,png_write_data,(png_structrp png_ptr,
    997     png_const_bytep data, png_size_t length),PNG_EMPTY);
    998 
    999 /* Read and check the PNG file signature */
   1000 PNG_INTERNAL_FUNCTION(void,png_read_sig,(png_structrp png_ptr,
   1001    png_inforp info_ptr),PNG_EMPTY);
   1002 
   1003 /* Read the chunk header (length + type name) */
   1004 PNG_INTERNAL_FUNCTION(png_uint_32,png_read_chunk_header,(png_structrp png_ptr),
   1005    PNG_EMPTY);
   1006 
   1007 /* Read data from whatever input you are using into the "data" buffer */
   1008 PNG_INTERNAL_FUNCTION(void,png_read_data,(png_structrp png_ptr, png_bytep data,
   1009     png_size_t length),PNG_EMPTY);
   1010 
   1011 /* Read bytes into buf, and update png_ptr->crc */
   1012 PNG_INTERNAL_FUNCTION(void,png_crc_read,(png_structrp png_ptr, png_bytep buf,
   1013     png_uint_32 length),PNG_EMPTY);
   1014 
   1015 /* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
   1016 PNG_INTERNAL_FUNCTION(int,png_crc_finish,(png_structrp png_ptr,
   1017    png_uint_32 skip),PNG_EMPTY);
   1018 
   1019 /* Read the CRC from the file and compare it to the libpng calculated CRC */
   1020 PNG_INTERNAL_FUNCTION(int,png_crc_error,(png_structrp png_ptr),PNG_EMPTY);
   1021 
   1022 /* Calculate the CRC over a section of data.  Note that we are only
   1023  * passing a maximum of 64K on systems that have this as a memory limit,
   1024  * since this is the maximum buffer size we can specify.
   1025  */
   1026 PNG_INTERNAL_FUNCTION(void,png_calculate_crc,(png_structrp png_ptr,
   1027    png_const_bytep ptr, png_size_t length),PNG_EMPTY);
   1028 
   1029 #ifdef PNG_WRITE_FLUSH_SUPPORTED
   1030 PNG_INTERNAL_FUNCTION(void,png_flush,(png_structrp png_ptr),PNG_EMPTY);
   1031 #endif
   1032 
   1033 /* Write various chunks */
   1034 
   1035 /* Write the IHDR chunk, and update the png_struct with the necessary
   1036  * information.
   1037  */
   1038 PNG_INTERNAL_FUNCTION(void,png_write_IHDR,(png_structrp png_ptr,
   1039    png_uint_32 width, png_uint_32 height, int bit_depth, int color_type,
   1040    int compression_method, int filter_method, int interlace_method),PNG_EMPTY);
   1041 
   1042 PNG_INTERNAL_FUNCTION(void,png_write_PLTE,(png_structrp png_ptr,
   1043    png_const_colorp palette, png_uint_32 num_pal),PNG_EMPTY);
   1044 
   1045 PNG_INTERNAL_FUNCTION(void,png_compress_IDAT,(png_structrp png_ptr,
   1046    png_const_bytep row_data, png_alloc_size_t row_data_length, int flush),
   1047    PNG_EMPTY);
   1048 
   1049 PNG_INTERNAL_FUNCTION(void,png_write_IEND,(png_structrp png_ptr),PNG_EMPTY);
   1050 
   1051 #ifdef PNG_WRITE_gAMA_SUPPORTED
   1052 PNG_INTERNAL_FUNCTION(void,png_write_gAMA_fixed,(png_structrp png_ptr,
   1053     png_fixed_point file_gamma),PNG_EMPTY);
   1054 #endif
   1055 
   1056 #ifdef PNG_WRITE_sBIT_SUPPORTED
   1057 PNG_INTERNAL_FUNCTION(void,png_write_sBIT,(png_structrp png_ptr,
   1058     png_const_color_8p sbit, int color_type),PNG_EMPTY);
   1059 #endif
   1060 
   1061 #ifdef PNG_WRITE_cHRM_SUPPORTED
   1062 PNG_INTERNAL_FUNCTION(void,png_write_cHRM_fixed,(png_structrp png_ptr,
   1063     const png_xy *xy), PNG_EMPTY);
   1064     /* The xy value must have been previously validated */
   1065 #endif
   1066 
   1067 #ifdef PNG_WRITE_sRGB_SUPPORTED
   1068 PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr,
   1069     int intent),PNG_EMPTY);
   1070 #endif
   1071 
   1072 #ifdef PNG_WRITE_iCCP_SUPPORTED
   1073 PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
   1074    png_const_charp name, png_const_bytep profile), PNG_EMPTY);
   1075    /* The profile must have been previously validated for correctness, the
   1076     * length comes from the first four bytes.  Only the base, deflate,
   1077     * compression is supported.
   1078     */
   1079 #endif
   1080 
   1081 #ifdef PNG_WRITE_sPLT_SUPPORTED
   1082 PNG_INTERNAL_FUNCTION(void,png_write_sPLT,(png_structrp png_ptr,
   1083     png_const_sPLT_tp palette),PNG_EMPTY);
   1084 #endif
   1085 
   1086 #ifdef PNG_WRITE_tRNS_SUPPORTED
   1087 PNG_INTERNAL_FUNCTION(void,png_write_tRNS,(png_structrp png_ptr,
   1088     png_const_bytep trans, png_const_color_16p values, int number,
   1089     int color_type),PNG_EMPTY);
   1090 #endif
   1091 
   1092 #ifdef PNG_WRITE_bKGD_SUPPORTED
   1093 PNG_INTERNAL_FUNCTION(void,png_write_bKGD,(png_structrp png_ptr,
   1094     png_const_color_16p values, int color_type),PNG_EMPTY);
   1095 #endif
   1096 
   1097 #ifdef PNG_WRITE_hIST_SUPPORTED
   1098 PNG_INTERNAL_FUNCTION(void,png_write_hIST,(png_structrp png_ptr,
   1099     png_const_uint_16p hist, int num_hist),PNG_EMPTY);
   1100 #endif
   1101 
   1102 /* Chunks that have keywords */
   1103 #ifdef PNG_WRITE_tEXt_SUPPORTED
   1104 PNG_INTERNAL_FUNCTION(void,png_write_tEXt,(png_structrp png_ptr,
   1105    png_const_charp key, png_const_charp text, png_size_t text_len),PNG_EMPTY);
   1106 #endif
   1107 
   1108 #ifdef PNG_WRITE_zTXt_SUPPORTED
   1109 PNG_INTERNAL_FUNCTION(void,png_write_zTXt,(png_structrp png_ptr, png_const_charp
   1110     key, png_const_charp text, int compression),PNG_EMPTY);
   1111 #endif
   1112 
   1113 #ifdef PNG_WRITE_iTXt_SUPPORTED
   1114 PNG_INTERNAL_FUNCTION(void,png_write_iTXt,(png_structrp png_ptr,
   1115     int compression, png_const_charp key, png_const_charp lang,
   1116     png_const_charp lang_key, png_const_charp text),PNG_EMPTY);
   1117 #endif
   1118 
   1119 #ifdef PNG_TEXT_SUPPORTED  /* Added at version 1.0.14 and 1.2.4 */
   1120 PNG_INTERNAL_FUNCTION(int,png_set_text_2,(png_const_structrp png_ptr,
   1121     png_inforp info_ptr, png_const_textp text_ptr, int num_text),PNG_EMPTY);
   1122 #endif
   1123 
   1124 #ifdef PNG_WRITE_oFFs_SUPPORTED
   1125 PNG_INTERNAL_FUNCTION(void,png_write_oFFs,(png_structrp png_ptr,
   1126     png_int_32 x_offset, png_int_32 y_offset, int unit_type),PNG_EMPTY);
   1127 #endif
   1128 
   1129 #ifdef PNG_WRITE_pCAL_SUPPORTED
   1130 PNG_INTERNAL_FUNCTION(void,png_write_pCAL,(png_structrp png_ptr,
   1131     png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams,
   1132     png_const_charp units, png_charpp params),PNG_EMPTY);
   1133 #endif
   1134 
   1135 #ifdef PNG_WRITE_pHYs_SUPPORTED
   1136 PNG_INTERNAL_FUNCTION(void,png_write_pHYs,(png_structrp png_ptr,
   1137     png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
   1138     int unit_type),PNG_EMPTY);
   1139 #endif
   1140 
   1141 #ifdef PNG_WRITE_tIME_SUPPORTED
   1142 PNG_INTERNAL_FUNCTION(void,png_write_tIME,(png_structrp png_ptr,
   1143     png_const_timep mod_time),PNG_EMPTY);
   1144 #endif
   1145 
   1146 #ifdef PNG_WRITE_sCAL_SUPPORTED
   1147 PNG_INTERNAL_FUNCTION(void,png_write_sCAL_s,(png_structrp png_ptr,
   1148     int unit, png_const_charp width, png_const_charp height),PNG_EMPTY);
   1149 #endif
   1150 
   1151 /* Called when finished processing a row of data */
   1152 PNG_INTERNAL_FUNCTION(void,png_write_finish_row,(png_structrp png_ptr),
   1153     PNG_EMPTY);
   1154 
   1155 /* Internal use only.   Called before first row of data */
   1156 PNG_INTERNAL_FUNCTION(void,png_write_start_row,(png_structrp png_ptr),
   1157     PNG_EMPTY);
   1158 
   1159 /* Combine a row of data, dealing with alpha, etc. if requested.  'row' is an
   1160  * array of png_ptr->width pixels.  If the image is not interlaced or this
   1161  * is the final pass this just does a memcpy, otherwise the "display" flag
   1162  * is used to determine whether to copy pixels that are not in the current pass.
   1163  *
   1164  * Because 'png_do_read_interlace' (below) replicates pixels this allows this
   1165  * function to achieve the documented 'blocky' appearance during interlaced read
   1166  * if display is 1 and the 'sparkle' appearance, where existing pixels in 'row'
   1167  * are not changed if they are not in the current pass, when display is 0.
   1168  *
   1169  * 'display' must be 0 or 1, otherwise the memcpy will be done regardless.
   1170  *
   1171  * The API always reads from the png_struct row buffer and always assumes that
   1172  * it is full width (png_do_read_interlace has already been called.)
   1173  *
   1174  * This function is only ever used to write to row buffers provided by the
   1175  * caller of the relevant libpng API and the row must have already been
   1176  * transformed by the read transformations.
   1177  *
   1178  * The PNG_USE_COMPILE_TIME_MASKS option causes generation of pre-computed
   1179  * bitmasks for use within the code, otherwise runtime generated masks are used.
   1180  * The default is compile time masks.
   1181  */
   1182 #ifndef PNG_USE_COMPILE_TIME_MASKS
   1183 #  define PNG_USE_COMPILE_TIME_MASKS 1
   1184 #endif
   1185 PNG_INTERNAL_FUNCTION(void,png_combine_row,(png_const_structrp png_ptr,
   1186     png_bytep row, int display),PNG_EMPTY);
   1187 
   1188 #ifdef PNG_READ_INTERLACING_SUPPORTED
   1189 /* Expand an interlaced row: the 'row_info' describes the pass data that has
   1190  * been read in and must correspond to the pixels in 'row', the pixels are
   1191  * expanded (moved apart) in 'row' to match the final layout, when doing this
   1192  * the pixels are *replicated* to the intervening space.  This is essential for
   1193  * the correct operation of png_combine_row, above.
   1194  */
   1195 PNG_INTERNAL_FUNCTION(void,png_do_read_interlace,(png_row_infop row_info,
   1196     png_bytep row, int pass, png_uint_32 transformations),PNG_EMPTY);
   1197 #endif
   1198 
   1199 /* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */
   1200 
   1201 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
   1202 /* Grab pixels out of a row for an interlaced pass */
   1203 PNG_INTERNAL_FUNCTION(void,png_do_write_interlace,(png_row_infop row_info,
   1204     png_bytep row, int pass),PNG_EMPTY);
   1205 #endif
   1206 
   1207 /* Unfilter a row: check the filter value before calling this, there is no point
   1208  * calling it for PNG_FILTER_VALUE_NONE.
   1209  */
   1210 PNG_INTERNAL_FUNCTION(void,png_read_filter_row,(png_structrp pp, png_row_infop
   1211     row_info, png_bytep row, png_const_bytep prev_row, int filter),PNG_EMPTY);
   1212 
   1213 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_neon,(png_row_infop row_info,
   1214     png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1215 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_neon,(png_row_infop
   1216     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1217 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_neon,(png_row_infop
   1218     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1219 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_neon,(png_row_infop
   1220     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1221 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_neon,(png_row_infop
   1222     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1223 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_neon,(png_row_infop
   1224     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1225 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_neon,(png_row_infop
   1226     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1227 
   1228 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
   1229     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1230 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
   1231     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1232 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
   1233     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1234 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
   1235     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1236 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
   1237     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1238 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
   1239     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1240 
   1241 /* Choose the best filter to use and filter the row data */
   1242 PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
   1243     png_row_infop row_info),PNG_EMPTY);
   1244 
   1245 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
   1246 PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
   1247    png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
   1248    /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
   1249     * is NULL the function checks, instead, for the end of the stream.  In this
   1250     * case a benign error will be issued if the stream end is not found or if
   1251     * extra data has to be consumed.
   1252     */
   1253 PNG_INTERNAL_FUNCTION(void,png_read_finish_IDAT,(png_structrp png_ptr),
   1254    PNG_EMPTY);
   1255    /* This cleans up when the IDAT LZ stream does not end when the last image
   1256     * byte is read; there is still some pending input.
   1257     */
   1258 
   1259 PNG_INTERNAL_FUNCTION(void,png_read_finish_row,(png_structrp png_ptr),
   1260    PNG_EMPTY);
   1261    /* Finish a row while reading, dealing with interlacing passes, etc. */
   1262 #endif /* SEQUENTIAL_READ */
   1263 
   1264 /* Initialize the row buffers, etc. */
   1265 PNG_INTERNAL_FUNCTION(void,png_read_start_row,(png_structrp png_ptr),PNG_EMPTY);
   1266 
   1267 #if PNG_ZLIB_VERNUM >= 0x1240
   1268 PNG_INTERNAL_FUNCTION(int,png_zlib_inflate,(png_structrp png_ptr, int flush),
   1269       PNG_EMPTY);
   1270 #  define PNG_INFLATE(pp, flush) png_zlib_inflate(pp, flush)
   1271 #else /* Zlib < 1.2.4 */
   1272 #  define PNG_INFLATE(pp, flush) inflate(&(pp)->zstream, flush)
   1273 #endif /* Zlib < 1.2.4 */
   1274 
   1275 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
   1276 /* Optional call to update the users info structure */
   1277 PNG_INTERNAL_FUNCTION(void,png_read_transform_info,(png_structrp png_ptr,
   1278     png_inforp info_ptr),PNG_EMPTY);
   1279 #endif
   1280 
   1281 /* Shared transform functions, defined in pngtran.c */
   1282 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
   1283     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
   1284 PNG_INTERNAL_FUNCTION(void,png_do_strip_channel,(png_row_infop row_info,
   1285     png_bytep row, int at_start),PNG_EMPTY);
   1286 #endif
   1287 
   1288 #ifdef PNG_16BIT_SUPPORTED
   1289 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
   1290 PNG_INTERNAL_FUNCTION(void,png_do_swap,(png_row_infop row_info,
   1291     png_bytep row),PNG_EMPTY);
   1292 #endif
   1293 #endif
   1294 
   1295 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
   1296     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
   1297 PNG_INTERNAL_FUNCTION(void,png_do_packswap,(png_row_infop row_info,
   1298     png_bytep row),PNG_EMPTY);
   1299 #endif
   1300 
   1301 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
   1302 PNG_INTERNAL_FUNCTION(void,png_do_invert,(png_row_infop row_info,
   1303     png_bytep row),PNG_EMPTY);
   1304 #endif
   1305 
   1306 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
   1307 PNG_INTERNAL_FUNCTION(void,png_do_bgr,(png_row_infop row_info,
   1308     png_bytep row),PNG_EMPTY);
   1309 #endif
   1310 
   1311 /* The following decodes the appropriate chunks, and does error correction,
   1312  * then calls the appropriate callback for the chunk if it is valid.
   1313  */
   1314 
   1315 /* Decode the IHDR chunk */
   1316 PNG_INTERNAL_FUNCTION(void,png_handle_IHDR,(png_structrp png_ptr,
   1317     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1318 PNG_INTERNAL_FUNCTION(void,png_handle_PLTE,(png_structrp png_ptr,
   1319     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1320 PNG_INTERNAL_FUNCTION(void,png_handle_IEND,(png_structrp png_ptr,
   1321     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1322 
   1323 #ifdef PNG_READ_bKGD_SUPPORTED
   1324 PNG_INTERNAL_FUNCTION(void,png_handle_bKGD,(png_structrp png_ptr,
   1325     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1326 #endif
   1327 
   1328 #ifdef PNG_READ_cHRM_SUPPORTED
   1329 PNG_INTERNAL_FUNCTION(void,png_handle_cHRM,(png_structrp png_ptr,
   1330     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1331 #endif
   1332 
   1333 #ifdef PNG_READ_gAMA_SUPPORTED
   1334 PNG_INTERNAL_FUNCTION(void,png_handle_gAMA,(png_structrp png_ptr,
   1335     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1336 #endif
   1337 
   1338 #ifdef PNG_READ_hIST_SUPPORTED
   1339 PNG_INTERNAL_FUNCTION(void,png_handle_hIST,(png_structrp png_ptr,
   1340     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1341 #endif
   1342 
   1343 #ifdef PNG_READ_iCCP_SUPPORTED
   1344 PNG_INTERNAL_FUNCTION(void,png_handle_iCCP,(png_structrp png_ptr,
   1345     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1346 #endif /* READ_iCCP */
   1347 
   1348 #ifdef PNG_READ_iTXt_SUPPORTED
   1349 PNG_INTERNAL_FUNCTION(void,png_handle_iTXt,(png_structrp png_ptr,
   1350     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1351 #endif
   1352 
   1353 #ifdef PNG_READ_oFFs_SUPPORTED
   1354 PNG_INTERNAL_FUNCTION(void,png_handle_oFFs,(png_structrp png_ptr,
   1355     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1356 #endif
   1357 
   1358 #ifdef PNG_READ_pCAL_SUPPORTED
   1359 PNG_INTERNAL_FUNCTION(void,png_handle_pCAL,(png_structrp png_ptr,
   1360     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1361 #endif
   1362 
   1363 #ifdef PNG_READ_pHYs_SUPPORTED
   1364 PNG_INTERNAL_FUNCTION(void,png_handle_pHYs,(png_structrp png_ptr,
   1365     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1366 #endif
   1367 
   1368 #ifdef PNG_READ_sBIT_SUPPORTED
   1369 PNG_INTERNAL_FUNCTION(void,png_handle_sBIT,(png_structrp png_ptr,
   1370     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1371 #endif
   1372 
   1373 #ifdef PNG_READ_sCAL_SUPPORTED
   1374 PNG_INTERNAL_FUNCTION(void,png_handle_sCAL,(png_structrp png_ptr,
   1375     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1376 #endif
   1377 
   1378 #ifdef PNG_READ_sPLT_SUPPORTED
   1379 PNG_INTERNAL_FUNCTION(void,png_handle_sPLT,(png_structrp png_ptr,
   1380     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1381 #endif /* READ_sPLT */
   1382 
   1383 #ifdef PNG_READ_sRGB_SUPPORTED
   1384 PNG_INTERNAL_FUNCTION(void,png_handle_sRGB,(png_structrp png_ptr,
   1385     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1386 #endif
   1387 
   1388 #ifdef PNG_READ_tEXt_SUPPORTED
   1389 PNG_INTERNAL_FUNCTION(void,png_handle_tEXt,(png_structrp png_ptr,
   1390     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1391 #endif
   1392 
   1393 #ifdef PNG_READ_tIME_SUPPORTED
   1394 PNG_INTERNAL_FUNCTION(void,png_handle_tIME,(png_structrp png_ptr,
   1395     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1396 #endif
   1397 
   1398 #ifdef PNG_READ_tRNS_SUPPORTED
   1399 PNG_INTERNAL_FUNCTION(void,png_handle_tRNS,(png_structrp png_ptr,
   1400     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1401 #endif
   1402 
   1403 #ifdef PNG_READ_zTXt_SUPPORTED
   1404 PNG_INTERNAL_FUNCTION(void,png_handle_zTXt,(png_structrp png_ptr,
   1405     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1406 #endif
   1407 
   1408 PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_structrp png_ptr,
   1409     png_uint_32 chunk_name),PNG_EMPTY);
   1410 
   1411 PNG_INTERNAL_FUNCTION(void,png_handle_unknown,(png_structrp png_ptr,
   1412     png_inforp info_ptr, png_uint_32 length, int keep),PNG_EMPTY);
   1413    /* This is the function that gets called for unknown chunks.  The 'keep'
   1414     * argument is either non-zero for a known chunk that has been set to be
   1415     * handled as unknown or zero for an unknown chunk.  By default the function
   1416     * just skips the chunk or errors out if it is critical.
   1417     */
   1418 
   1419 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
   1420     defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
   1421 PNG_INTERNAL_FUNCTION(int,png_chunk_unknown_handling,
   1422     (png_const_structrp png_ptr, png_uint_32 chunk_name),PNG_EMPTY);
   1423    /* Exactly as the API png_handle_as_unknown() except that the argument is a
   1424     * 32-bit chunk name, not a string.
   1425     */
   1426 #endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
   1427 
   1428 /* Handle the transformations for reading and writing */
   1429 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
   1430 PNG_INTERNAL_FUNCTION(void,png_do_read_transformations,(png_structrp png_ptr,
   1431    png_row_infop row_info),PNG_EMPTY);
   1432 #endif
   1433 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
   1434 PNG_INTERNAL_FUNCTION(void,png_do_write_transformations,(png_structrp png_ptr,
   1435    png_row_infop row_info),PNG_EMPTY);
   1436 #endif
   1437 
   1438 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
   1439 PNG_INTERNAL_FUNCTION(void,png_init_read_transformations,(png_structrp png_ptr),
   1440     PNG_EMPTY);
   1441 #endif
   1442 
   1443 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
   1444 PNG_INTERNAL_FUNCTION(void,png_push_read_chunk,(png_structrp png_ptr,
   1445     png_inforp info_ptr),PNG_EMPTY);
   1446 PNG_INTERNAL_FUNCTION(void,png_push_read_sig,(png_structrp png_ptr,
   1447     png_inforp info_ptr),PNG_EMPTY);
   1448 PNG_INTERNAL_FUNCTION(void,png_push_check_crc,(png_structrp png_ptr),PNG_EMPTY);
   1449 PNG_INTERNAL_FUNCTION(void,png_push_save_buffer,(png_structrp png_ptr),
   1450     PNG_EMPTY);
   1451 PNG_INTERNAL_FUNCTION(void,png_push_restore_buffer,(png_structrp png_ptr,
   1452     png_bytep buffer, png_size_t buffer_length),PNG_EMPTY);
   1453 PNG_INTERNAL_FUNCTION(void,png_push_read_IDAT,(png_structrp png_ptr),PNG_EMPTY);
   1454 PNG_INTERNAL_FUNCTION(void,png_process_IDAT_data,(png_structrp png_ptr,
   1455     png_bytep buffer, png_size_t buffer_length),PNG_EMPTY);
   1456 PNG_INTERNAL_FUNCTION(void,png_push_process_row,(png_structrp png_ptr),
   1457     PNG_EMPTY);
   1458 PNG_INTERNAL_FUNCTION(void,png_push_handle_unknown,(png_structrp png_ptr,
   1459    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1460 PNG_INTERNAL_FUNCTION(void,png_push_have_info,(png_structrp png_ptr,
   1461    png_inforp info_ptr),PNG_EMPTY);
   1462 PNG_INTERNAL_FUNCTION(void,png_push_have_end,(png_structrp png_ptr,
   1463    png_inforp info_ptr),PNG_EMPTY);
   1464 PNG_INTERNAL_FUNCTION(void,png_push_have_row,(png_structrp png_ptr,
   1465      png_bytep row),PNG_EMPTY);
   1466 PNG_INTERNAL_FUNCTION(void,png_push_read_end,(png_structrp png_ptr,
   1467     png_inforp info_ptr),PNG_EMPTY);
   1468 PNG_INTERNAL_FUNCTION(void,png_process_some_data,(png_structrp png_ptr,
   1469     png_inforp info_ptr),PNG_EMPTY);
   1470 PNG_INTERNAL_FUNCTION(void,png_read_push_finish_row,(png_structrp png_ptr),
   1471     PNG_EMPTY);
   1472 #  ifdef PNG_READ_tEXt_SUPPORTED
   1473 PNG_INTERNAL_FUNCTION(void,png_push_handle_tEXt,(png_structrp png_ptr,
   1474     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1475 PNG_INTERNAL_FUNCTION(void,png_push_read_tEXt,(png_structrp png_ptr,
   1476     png_inforp info_ptr),PNG_EMPTY);
   1477 #  endif
   1478 #  ifdef PNG_READ_zTXt_SUPPORTED
   1479 PNG_INTERNAL_FUNCTION(void,png_push_handle_zTXt,(png_structrp png_ptr,
   1480     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1481 PNG_INTERNAL_FUNCTION(void,png_push_read_zTXt,(png_structrp png_ptr,
   1482     png_inforp info_ptr),PNG_EMPTY);
   1483 #  endif
   1484 #  ifdef PNG_READ_iTXt_SUPPORTED
   1485 PNG_INTERNAL_FUNCTION(void,png_push_handle_iTXt,(png_structrp png_ptr,
   1486     png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1487 PNG_INTERNAL_FUNCTION(void,png_push_read_iTXt,(png_structrp png_ptr,
   1488     png_inforp info_ptr),PNG_EMPTY);
   1489 #  endif
   1490 
   1491 #endif /* PROGRESSIVE_READ */
   1492 
   1493 /* Added at libpng version 1.6.0 */
   1494 #ifdef PNG_GAMMA_SUPPORTED
   1495 PNG_INTERNAL_FUNCTION(void,png_colorspace_set_gamma,(png_const_structrp png_ptr,
   1496     png_colorspacerp colorspace, png_fixed_point gAMA), PNG_EMPTY);
   1497    /* Set the colorspace gamma with a value provided by the application or by
   1498     * the gAMA chunk on read.  The value will override anything set by an ICC
   1499     * profile.
   1500     */
   1501 
   1502 PNG_INTERNAL_FUNCTION(void,png_colorspace_sync_info,(png_const_structrp png_ptr,
   1503     png_inforp info_ptr), PNG_EMPTY);
   1504     /* Synchronize the info 'valid' flags with the colorspace */
   1505 
   1506 PNG_INTERNAL_FUNCTION(void,png_colorspace_sync,(png_const_structrp png_ptr,
   1507     png_inforp info_ptr), PNG_EMPTY);
   1508     /* Copy the png_struct colorspace to the info_struct and call the above to
   1509      * synchronize the flags.  Checks for NULL info_ptr and does nothing.
   1510      */
   1511 #endif
   1512 
   1513 /* Added at libpng version 1.4.0 */
   1514 #ifdef PNG_COLORSPACE_SUPPORTED
   1515 /* These internal functions are for maintaining the colorspace structure within
   1516  * a png_info or png_struct (or, indeed, both).
   1517  */
   1518 PNG_INTERNAL_FUNCTION(int,png_colorspace_set_chromaticities,
   1519    (png_const_structrp png_ptr, png_colorspacerp colorspace, const png_xy *xy,
   1520     int preferred), PNG_EMPTY);
   1521 
   1522 PNG_INTERNAL_FUNCTION(int,png_colorspace_set_endpoints,
   1523    (png_const_structrp png_ptr, png_colorspacerp colorspace, const png_XYZ *XYZ,
   1524     int preferred), PNG_EMPTY);
   1525 
   1526 #ifdef PNG_sRGB_SUPPORTED
   1527 PNG_INTERNAL_FUNCTION(int,png_colorspace_set_sRGB,(png_const_structrp png_ptr,
   1528    png_colorspacerp colorspace, int intent), PNG_EMPTY);
   1529    /* This does set the colorspace gAMA and cHRM values too, but doesn't set the
   1530     * flags to write them, if it returns false there was a problem and an error
   1531     * message has already been output (but the colorspace may still need to be
   1532     * synced to record the invalid flag).
   1533     */
   1534 #endif /* sRGB */
   1535 
   1536 #ifdef PNG_iCCP_SUPPORTED
   1537 PNG_INTERNAL_FUNCTION(int,png_colorspace_set_ICC,(png_const_structrp png_ptr,
   1538    png_colorspacerp colorspace, png_const_charp name,
   1539    png_uint_32 profile_length, png_const_bytep profile, int color_type),
   1540    PNG_EMPTY);
   1541    /* The 'name' is used for information only */
   1542 
   1543 /* Routines for checking parts of an ICC profile. */
   1544 #ifdef PNG_READ_iCCP_SUPPORTED
   1545 PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
   1546    png_colorspacerp colorspace, png_const_charp name,
   1547    png_uint_32 profile_length), PNG_EMPTY);
   1548 #endif /* READ_iCCP */
   1549 PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
   1550    png_colorspacerp colorspace, png_const_charp name,
   1551    png_uint_32 profile_length,
   1552    png_const_bytep profile /* first 132 bytes only */, int color_type),
   1553    PNG_EMPTY);
   1554 PNG_INTERNAL_FUNCTION(int,png_icc_check_tag_table,(png_const_structrp png_ptr,
   1555    png_colorspacerp colorspace, png_const_charp name,
   1556    png_uint_32 profile_length,
   1557    png_const_bytep profile /* header plus whole tag table */), PNG_EMPTY);
   1558 #ifdef PNG_sRGB_SUPPORTED
   1559 PNG_INTERNAL_FUNCTION(void,png_icc_set_sRGB,(
   1560    png_const_structrp png_ptr, png_colorspacerp colorspace,
   1561    png_const_bytep profile, uLong adler), PNG_EMPTY);
   1562    /* 'adler' is the Adler32 checksum of the uncompressed profile data. It may
   1563     * be zero to indicate that it is not available.  It is used, if provided,
   1564     * as a fast check on the profile when checking to see if it is sRGB.
   1565     */
   1566 #endif
   1567 #endif /* iCCP */
   1568 
   1569 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
   1570 PNG_INTERNAL_FUNCTION(void,png_colorspace_set_rgb_coefficients,
   1571    (png_structrp png_ptr), PNG_EMPTY);
   1572    /* Set the rgb_to_gray coefficients from the colorspace Y values */
   1573 #endif /* READ_RGB_TO_GRAY */
   1574 #endif /* COLORSPACE */
   1575 
   1576 /* Added at libpng version 1.4.0 */
   1577 PNG_INTERNAL_FUNCTION(void,png_check_IHDR,(png_const_structrp png_ptr,
   1578     png_uint_32 width, png_uint_32 height, int bit_depth,
   1579     int color_type, int interlace_type, int compression_type,
   1580     int filter_type),PNG_EMPTY);
   1581 
   1582 /* Added at libpng version 1.5.10 */
   1583 #if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
   1584     defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
   1585 PNG_INTERNAL_FUNCTION(void,png_do_check_palette_indexes,
   1586    (png_structrp png_ptr, png_row_infop row_info),PNG_EMPTY);
   1587 #endif
   1588 
   1589 #if defined(PNG_FLOATING_POINT_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
   1590 PNG_INTERNAL_FUNCTION(void,png_fixed_error,(png_const_structrp png_ptr,
   1591    png_const_charp name),PNG_NORETURN);
   1592 #endif
   1593 
   1594 /* Puts 'string' into 'buffer' at buffer[pos], taking care never to overwrite
   1595  * the end.  Always leaves the buffer nul terminated.  Never errors out (and
   1596  * there is no error code.)
   1597  */
   1598 PNG_INTERNAL_FUNCTION(size_t,png_safecat,(png_charp buffer, size_t bufsize,
   1599    size_t pos, png_const_charp string),PNG_EMPTY);
   1600 
   1601 /* Various internal functions to handle formatted warning messages, currently
   1602  * only implemented for warnings.
   1603  */
   1604 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
   1605 /* Utility to dump an unsigned value into a buffer, given a start pointer and
   1606  * and end pointer (which should point just *beyond* the end of the buffer!)
   1607  * Returns the pointer to the start of the formatted string.  This utility only
   1608  * does unsigned values.
   1609  */
   1610 PNG_INTERNAL_FUNCTION(png_charp,png_format_number,(png_const_charp start,
   1611    png_charp end, int format, png_alloc_size_t number),PNG_EMPTY);
   1612 
   1613 /* Convenience macro that takes an array: */
   1614 #define PNG_FORMAT_NUMBER(buffer,format,number) \
   1615    png_format_number(buffer, buffer + (sizeof buffer), format, number)
   1616 
   1617 /* Suggested size for a number buffer (enough for 64 bits and a sign!) */
   1618 #define PNG_NUMBER_BUFFER_SIZE 24
   1619 
   1620 /* These are the integer formats currently supported, the name is formed from
   1621  * the standard printf(3) format string.
   1622  */
   1623 #define PNG_NUMBER_FORMAT_u     1 /* chose unsigned API! */
   1624 #define PNG_NUMBER_FORMAT_02u   2
   1625 #define PNG_NUMBER_FORMAT_d     1 /* chose signed API! */
   1626 #define PNG_NUMBER_FORMAT_02d   2
   1627 #define PNG_NUMBER_FORMAT_x     3
   1628 #define PNG_NUMBER_FORMAT_02x   4
   1629 #define PNG_NUMBER_FORMAT_fixed 5 /* choose the signed API */
   1630 #endif
   1631 
   1632 #ifdef PNG_WARNINGS_SUPPORTED
   1633 /* New defines and members adding in libpng-1.5.4 */
   1634 #  define PNG_WARNING_PARAMETER_SIZE 32
   1635 #  define PNG_WARNING_PARAMETER_COUNT 8 /* Maximum 9; see pngerror.c */
   1636 
   1637 /* An l-value of this type has to be passed to the APIs below to cache the
   1638  * values of the parameters to a formatted warning message.
   1639  */
   1640 typedef char png_warning_parameters[PNG_WARNING_PARAMETER_COUNT][
   1641    PNG_WARNING_PARAMETER_SIZE];
   1642 
   1643 PNG_INTERNAL_FUNCTION(void,png_warning_parameter,(png_warning_parameters p,
   1644    int number, png_const_charp string),PNG_EMPTY);
   1645    /* Parameters are limited in size to PNG_WARNING_PARAMETER_SIZE characters,
   1646     * including the trailing '\0'.
   1647     */
   1648 PNG_INTERNAL_FUNCTION(void,png_warning_parameter_unsigned,
   1649    (png_warning_parameters p, int number, int format, png_alloc_size_t value),
   1650    PNG_EMPTY);
   1651    /* Use png_alloc_size_t because it is an unsigned type as big as any we
   1652     * need to output.  Use the following for a signed value.
   1653     */
   1654 PNG_INTERNAL_FUNCTION(void,png_warning_parameter_signed,
   1655    (png_warning_parameters p, int number, int format, png_int_32 value),
   1656    PNG_EMPTY);
   1657 
   1658 PNG_INTERNAL_FUNCTION(void,png_formatted_warning,(png_const_structrp png_ptr,
   1659    png_warning_parameters p, png_const_charp message),PNG_EMPTY);
   1660    /* 'message' follows the X/Open approach of using @1, @2 to insert
   1661     * parameters previously supplied using the above functions.  Errors in
   1662     * specifying the parameters will simply result in garbage substitutions.
   1663     */
   1664 #endif
   1665 
   1666 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
   1667 /* Application errors (new in 1.6); use these functions (declared below) for
   1668  * errors in the parameters or order of API function calls on read.  The
   1669  * 'warning' should be used for an error that can be handled completely; the
   1670  * 'error' for one which can be handled safely but which may lose application
   1671  * information or settings.
   1672  *
   1673  * By default these both result in a png_error call prior to release, while in a
   1674  * released version the 'warning' is just a warning.  However if the application
   1675  * explicitly disables benign errors (explicitly permitting the code to lose
   1676  * information) they both turn into warnings.
   1677  *
   1678  * If benign errors aren't supported they end up as the corresponding base call
   1679  * (png_warning or png_error.)
   1680  */
   1681 PNG_INTERNAL_FUNCTION(void,png_app_warning,(png_const_structrp png_ptr,
   1682    png_const_charp message),PNG_EMPTY);
   1683    /* The application provided invalid parameters to an API function or called
   1684     * an API function at the wrong time, libpng can completely recover.
   1685     */
   1686 
   1687 PNG_INTERNAL_FUNCTION(void,png_app_error,(png_const_structrp png_ptr,
   1688    png_const_charp message),PNG_EMPTY);
   1689    /* As above but libpng will ignore the call, or attempt some other partial
   1690     * recovery from the error.
   1691     */
   1692 #else
   1693 #  define png_app_warning(pp,s) png_warning(pp,s)
   1694 #  define png_app_error(pp,s) png_error(pp,s)
   1695 #endif
   1696 
   1697 PNG_INTERNAL_FUNCTION(void,png_chunk_report,(png_const_structrp png_ptr,
   1698    png_const_charp message, int error),PNG_EMPTY);
   1699    /* Report a recoverable issue in chunk data.  On read this is used to report
   1700     * a problem found while reading a particular chunk and the
   1701     * png_chunk_benign_error or png_chunk_warning function is used as
   1702     * appropriate.  On write this is used to report an error that comes from
   1703     * data set via an application call to a png_set_ API and png_app_error or
   1704     * png_app_warning is used as appropriate.
   1705     *
   1706     * The 'error' parameter must have one of the following values:
   1707     */
   1708 #define PNG_CHUNK_WARNING     0 /* never an error */
   1709 #define PNG_CHUNK_WRITE_ERROR 1 /* an error only on write */
   1710 #define PNG_CHUNK_ERROR       2 /* always an error */
   1711 
   1712 /* ASCII to FP interfaces, currently only implemented if sCAL
   1713  * support is required.
   1714  */
   1715 #if defined(PNG_sCAL_SUPPORTED)
   1716 /* MAX_DIGITS is actually the maximum number of characters in an sCAL
   1717  * width or height, derived from the precision (number of significant
   1718  * digits - a build time settable option) and assumptions about the
   1719  * maximum ridiculous exponent.
   1720  */
   1721 #define PNG_sCAL_MAX_DIGITS (PNG_sCAL_PRECISION+1/*.*/+1/*E*/+10/*exponent*/)
   1722 
   1723 #ifdef PNG_FLOATING_POINT_SUPPORTED
   1724 PNG_INTERNAL_FUNCTION(void,png_ascii_from_fp,(png_const_structrp png_ptr,
   1725    png_charp ascii, png_size_t size, double fp, unsigned int precision),
   1726    PNG_EMPTY);
   1727 #endif /* FLOATING_POINT */
   1728 
   1729 #ifdef PNG_FIXED_POINT_SUPPORTED
   1730 PNG_INTERNAL_FUNCTION(void,png_ascii_from_fixed,(png_const_structrp png_ptr,
   1731    png_charp ascii, png_size_t size, png_fixed_point fp),PNG_EMPTY);
   1732 #endif /* FIXED_POINT */
   1733 #endif /* sCAL */
   1734 
   1735 #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
   1736 /* An internal API to validate the format of a floating point number.
   1737  * The result is the index of the next character.  If the number is
   1738  * not valid it will be the index of a character in the supposed number.
   1739  *
   1740  * The format of a number is defined in the PNG extensions specification
   1741  * and this API is strictly conformant to that spec, not anyone elses!
   1742  *
   1743  * The format as a regular expression is:
   1744  *
   1745  * [+-]?[0-9]+.?([Ee][+-]?[0-9]+)?
   1746  *
   1747  * or:
   1748  *
   1749  * [+-]?.[0-9]+(.[0-9]+)?([Ee][+-]?[0-9]+)?
   1750  *
   1751  * The complexity is that either integer or fraction must be present and the
   1752  * fraction is permitted to have no digits only if the integer is present.
   1753  *
   1754  * NOTE: The dangling E problem.
   1755  *   There is a PNG valid floating point number in the following:
   1756  *
   1757  *       PNG floating point numbers are not greedy.
   1758  *
   1759  *   Working this out requires *TWO* character lookahead (because of the
   1760  *   sign), the parser does not do this - it will fail at the 'r' - this
   1761  *   doesn't matter for PNG sCAL chunk values, but it requires more care
   1762  *   if the value were ever to be embedded in something more complex.  Use
   1763  *   ANSI-C strtod if you need the lookahead.
   1764  */
   1765 /* State table for the parser. */
   1766 #define PNG_FP_INTEGER    0  /* before or in integer */
   1767 #define PNG_FP_FRACTION   1  /* before or in fraction */
   1768 #define PNG_FP_EXPONENT   2  /* before or in exponent */
   1769 #define PNG_FP_STATE      3  /* mask for the above */
   1770 #define PNG_FP_SAW_SIGN   4  /* Saw +/- in current state */
   1771 #define PNG_FP_SAW_DIGIT  8  /* Saw a digit in current state */
   1772 #define PNG_FP_SAW_DOT   16  /* Saw a dot in current state */
   1773 #define PNG_FP_SAW_E     32  /* Saw an E (or e) in current state */
   1774 #define PNG_FP_SAW_ANY   60  /* Saw any of the above 4 */
   1775 
   1776 /* These three values don't affect the parser.  They are set but not used.
   1777  */
   1778 #define PNG_FP_WAS_VALID 64  /* Preceding substring is a valid fp number */
   1779 #define PNG_FP_NEGATIVE 128  /* A negative number, including "-0" */
   1780 #define PNG_FP_NONZERO  256  /* A non-zero value */
   1781 #define PNG_FP_STICKY   448  /* The above three flags */
   1782 
   1783 /* This is available for the caller to store in 'state' if required.  Do not
   1784  * call the parser after setting it (the parser sometimes clears it.)
   1785  */
   1786 #define PNG_FP_INVALID  512  /* Available for callers as a distinct value */
   1787 
   1788 /* Result codes for the parser (boolean - true meants ok, false means
   1789  * not ok yet.)
   1790  */
   1791 #define PNG_FP_MAYBE      0  /* The number may be valid in the future */
   1792 #define PNG_FP_OK         1  /* The number is valid */
   1793 
   1794 /* Tests on the sticky non-zero and negative flags.  To pass these checks
   1795  * the state must also indicate that the whole number is valid - this is
   1796  * achieved by testing PNG_FP_SAW_DIGIT (see the implementation for why this
   1797  * is equivalent to PNG_FP_OK above.)
   1798  */
   1799 #define PNG_FP_NZ_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NEGATIVE | PNG_FP_NONZERO)
   1800    /* NZ_MASK: the string is valid and a non-zero negative value */
   1801 #define PNG_FP_Z_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NONZERO)
   1802    /* Z MASK: the string is valid and a non-zero value. */
   1803    /* PNG_FP_SAW_DIGIT: the string is valid. */
   1804 #define PNG_FP_IS_ZERO(state) (((state) & PNG_FP_Z_MASK) == PNG_FP_SAW_DIGIT)
   1805 #define PNG_FP_IS_POSITIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_Z_MASK)
   1806 #define PNG_FP_IS_NEGATIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_NZ_MASK)
   1807 
   1808 /* The actual parser.  This can be called repeatedly. It updates
   1809  * the index into the string and the state variable (which must
   1810  * be initialized to 0).  It returns a result code, as above.  There
   1811  * is no point calling the parser any more if it fails to advance to
   1812  * the end of the string - it is stuck on an invalid character (or
   1813  * terminated by '\0').
   1814  *
   1815  * Note that the pointer will consume an E or even an E+ and then leave
   1816  * a 'maybe' state even though a preceding integer.fraction is valid.
   1817  * The PNG_FP_WAS_VALID flag indicates that a preceding substring was
   1818  * a valid number.  It's possible to recover from this by calling
   1819  * the parser again (from the start, with state 0) but with a string
   1820  * that omits the last character (i.e. set the size to the index of
   1821  * the problem character.)  This has not been tested within libpng.
   1822  */
   1823 PNG_INTERNAL_FUNCTION(int,png_check_fp_number,(png_const_charp string,
   1824    png_size_t size, int *statep, png_size_tp whereami),PNG_EMPTY);
   1825 
   1826 /* This is the same but it checks a complete string and returns true
   1827  * only if it just contains a floating point number.  As of 1.5.4 this
   1828  * function also returns the state at the end of parsing the number if
   1829  * it was valid (otherwise it returns 0.)  This can be used for testing
   1830  * for negative or zero values using the sticky flag.
   1831  */
   1832 PNG_INTERNAL_FUNCTION(int,png_check_fp_string,(png_const_charp string,
   1833    png_size_t size),PNG_EMPTY);
   1834 #endif /* pCAL || sCAL */
   1835 
   1836 #if defined(PNG_GAMMA_SUPPORTED) ||\
   1837     defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
   1838 /* Added at libpng version 1.5.0 */
   1839 /* This is a utility to provide a*times/div (rounded) and indicate
   1840  * if there is an overflow.  The result is a boolean - false (0)
   1841  * for overflow, true (1) if no overflow, in which case *res
   1842  * holds the result.
   1843  */
   1844 PNG_INTERNAL_FUNCTION(int,png_muldiv,(png_fixed_point_p res, png_fixed_point a,
   1845    png_int_32 multiplied_by, png_int_32 divided_by),PNG_EMPTY);
   1846 #endif
   1847 
   1848 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
   1849 /* Same deal, but issue a warning on overflow and return 0. */
   1850 PNG_INTERNAL_FUNCTION(png_fixed_point,png_muldiv_warn,
   1851    (png_const_structrp png_ptr, png_fixed_point a, png_int_32 multiplied_by,
   1852    png_int_32 divided_by),PNG_EMPTY);
   1853 #endif
   1854 
   1855 #ifdef PNG_GAMMA_SUPPORTED
   1856 /* Calculate a reciprocal - used for gamma values.  This returns
   1857  * 0 if the argument is 0 in order to maintain an undefined value;
   1858  * there are no warnings.
   1859  */
   1860 PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal,(png_fixed_point a),
   1861    PNG_EMPTY);
   1862 
   1863 #ifdef PNG_READ_GAMMA_SUPPORTED
   1864 /* The same but gives a reciprocal of the product of two fixed point
   1865  * values.  Accuracy is suitable for gamma calculations but this is
   1866  * not exact - use png_muldiv for that.  Only required at present on read.
   1867  */
   1868 PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal2,(png_fixed_point a,
   1869    png_fixed_point b),PNG_EMPTY);
   1870 #endif
   1871 
   1872 /* Return true if the gamma value is significantly different from 1.0 */
   1873 PNG_INTERNAL_FUNCTION(int,png_gamma_significant,(png_fixed_point gamma_value),
   1874    PNG_EMPTY);
   1875 #endif
   1876 
   1877 #ifdef PNG_READ_GAMMA_SUPPORTED
   1878 /* Internal fixed point gamma correction.  These APIs are called as
   1879  * required to convert single values - they don't need to be fast,
   1880  * they are not used when processing image pixel values.
   1881  *
   1882  * While the input is an 'unsigned' value it must actually be the
   1883  * correct bit value - 0..255 or 0..65535 as required.
   1884  */
   1885 PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_correct,(png_structrp png_ptr,
   1886    unsigned int value, png_fixed_point gamma_value),PNG_EMPTY);
   1887 PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_16bit_correct,(unsigned int value,
   1888    png_fixed_point gamma_value),PNG_EMPTY);
   1889 PNG_INTERNAL_FUNCTION(png_byte,png_gamma_8bit_correct,(unsigned int value,
   1890    png_fixed_point gamma_value),PNG_EMPTY);
   1891 PNG_INTERNAL_FUNCTION(void,png_destroy_gamma_table,(png_structrp png_ptr),
   1892    PNG_EMPTY);
   1893 PNG_INTERNAL_FUNCTION(void,png_build_gamma_table,(png_structrp png_ptr,
   1894    int bit_depth),PNG_EMPTY);
   1895 #endif
   1896 
   1897 /* SIMPLIFIED READ/WRITE SUPPORT */
   1898 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
   1899    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
   1900 /* The internal structure that png_image::opaque points to. */
   1901 typedef struct png_control
   1902 {
   1903    png_structp png_ptr;
   1904    png_infop   info_ptr;
   1905    png_voidp   error_buf;           /* Always a jmp_buf at present. */
   1906 
   1907    png_const_bytep memory;          /* Memory buffer. */
   1908    png_size_t      size;            /* Size of the memory buffer. */
   1909 
   1910    unsigned int for_write       :1; /* Otherwise it is a read structure */
   1911    unsigned int owned_file      :1; /* We own the file in io_ptr */
   1912 } png_control;
   1913 
   1914 /* Return the pointer to the jmp_buf from a png_control: necessary because C
   1915  * does not reveal the type of the elements of jmp_buf.
   1916  */
   1917 #ifdef __cplusplus
   1918 #  define png_control_jmp_buf(pc) (((jmp_buf*)((pc)->error_buf))[0])
   1919 #else
   1920 #  define png_control_jmp_buf(pc) ((pc)->error_buf)
   1921 #endif
   1922 
   1923 /* Utility to safely execute a piece of libpng code catching and logging any
   1924  * errors that might occur.  Returns true on success, false on failure (either
   1925  * of the function or as a result of a png_error.)
   1926  */
   1927 PNG_INTERNAL_CALLBACK(void,png_safe_error,(png_structp png_ptr,
   1928    png_const_charp error_message),PNG_NORETURN);
   1929 
   1930 #ifdef PNG_WARNINGS_SUPPORTED
   1931 PNG_INTERNAL_CALLBACK(void,png_safe_warning,(png_structp png_ptr,
   1932    png_const_charp warning_message),PNG_EMPTY);
   1933 #else
   1934 #  define png_safe_warning 0/*dummy argument*/
   1935 #endif
   1936 
   1937 PNG_INTERNAL_FUNCTION(int,png_safe_execute,(png_imagep image,
   1938    int (*function)(png_voidp), png_voidp arg),PNG_EMPTY);
   1939 
   1940 /* Utility to log an error; this also cleans up the png_image; the function
   1941  * always returns 0 (false).
   1942  */
   1943 PNG_INTERNAL_FUNCTION(int,png_image_error,(png_imagep image,
   1944    png_const_charp error_message),PNG_EMPTY);
   1945 
   1946 #ifndef PNG_SIMPLIFIED_READ_SUPPORTED
   1947 /* png_image_free is used by the write code but not exported */
   1948 PNG_INTERNAL_FUNCTION(void, png_image_free, (png_imagep image), PNG_EMPTY);
   1949 #endif /* !SIMPLIFIED_READ */
   1950 
   1951 #endif /* SIMPLIFIED READ/WRITE */
   1952 
   1953 /* These are initialization functions for hardware specific PNG filter
   1954  * optimizations; list these here then select the appropriate one at compile
   1955  * time using the macro PNG_FILTER_OPTIMIZATIONS.  If the macro is not defined
   1956  * the generic code is used.
   1957  */
   1958 #ifdef PNG_FILTER_OPTIMIZATIONS
   1959 PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
   1960    unsigned int bpp), PNG_EMPTY);
   1961    /* Just declare the optimization that will be used */
   1962 #else
   1963    /* List *all* the possible optimizations here - this branch is required if
   1964     * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
   1965     * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
   1966     */
   1967 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
   1968    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   1969 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
   1970    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   1971 #endif
   1972 
   1973 PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
   1974    png_const_charp key, png_bytep new_key), PNG_EMPTY);
   1975 
   1976 /* Maintainer: Put new private prototypes here ^ */
   1977 
   1978 #include "pngdebug.h"
   1979 
   1980 #ifdef __cplusplus
   1981 }
   1982 #endif
   1983 
   1984 #endif /* PNG_VERSION_INFO_ONLY */
   1985 #endif /* PNGPRIV_H */
   1986