media/libpng/pngpriv.h
author Bryce Van Dyk <bvandyk@mozilla.com>
Wed, 26 Sep 2018 16:34:32 +0000
changeset 496769 e6f8e822851acb248df066141c3f2a6dcbad20d6
parent 495448 4e5643db5a23372cc1095c5ef60eca76b958c493
child 532453 179c0370dfa12b59d2214509d41a8356962f5df7
permissions -rw-r--r--
Bug 1494178 - Add check to ChromiumCDMChild to mark samples with 0 encrypted bytes as unencrypted. r=cpearce With the addition of an explicit encryption enum for CDM10 input data, if a sample has 0 encrypted bytes it must be marked as unencrypted. Historically we could let the CDM figure out based on the unencrypted + encrypted bytes. However, if we mark a sample as encrypted but it has 0 encrypted bytes, the CDM will fail to decrypt. This changeset adds a check to gracefully handle samples that are marked as encrypted but with no encrypted ranges. In such cases we mark the data as unencrypted and log that such data was encountered. This means we don't break playback of encrypted media should we overlook such cases, but have better detection via logging. Differential Revision: https://phabricator.services.mozilla.com/D6873


/* pngpriv.h - private declarations for use inside libpng
 *
 * Last changed in libpng 1.6.35 [July 15, 2018]
 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

/* The symbols declared in this file (including the functions declared
 * as extern) are PRIVATE.  They are not part of the libpng public
 * interface, and are not recommended for use by regular applications.
 * Some of them may become public in the future; others may stay private,
 * change in an incompatible way, or even disappear.
 * Although the libpng users are not forbidden to include this header,
 * they should be well aware of the issues that may arise from doing so.
 */

#ifndef PNGPRIV_H
#define PNGPRIV_H

/* Feature Test Macros.  The following are defined here to ensure that correctly
 * implemented libraries reveal the APIs libpng needs to build and hide those
 * that are not needed and potentially damaging to the compilation.
 *
 * Feature Test Macros must be defined before any system header is included (see
 * POSIX 1003.1 2.8.2 "POSIX Symbols."
 *
 * These macros only have an effect if the operating system supports either
 * POSIX 1003.1 or C99, or both.  On other operating systems (particularly
 * Windows/Visual Studio) there is no effect; the OS specific tests below are
 * still required (as of 2011-05-02.)
 */
#ifndef _POSIX_SOURCE
# define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
#endif

#ifndef PNG_VERSION_INFO_ONLY
/* Standard library headers not required by png.h: */
#  include <stdlib.h>
#  include <string.h>
#endif

#define PNGLIB_BUILD /*libpng is being built, not used*/

/* If HAVE_CONFIG_H is defined during the build then the build system must
 * provide an appropriate "config.h" file on the include path.  The header file
 * must provide definitions as required below (search for "HAVE_CONFIG_H");
 * see configure.ac for more details of the requirements.  The macro
 * "PNG_NO_CONFIG_H" is provided for maintainers to test for dependencies on
 * 'configure'; define this macro to prevent the configure build including the
 * configure generated config.h.  Libpng is expected to compile without *any*
 * special build system support on a reasonably ANSI-C compliant system.
 */
#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
#  include <config.h>

   /* Pick up the definition of 'restrict' from config.h if it was read: */
#  define PNG_RESTRICT restrict
#endif

/* To support symbol prefixing it is necessary to know *before* including png.h
 * whether the fixed point (and maybe other) APIs are exported, because if they
 * are not internal definitions may be required.  This is handled below just
 * before png.h is included, but load the configuration now if it is available.
 */
#ifndef PNGLCONF_H
#  include "pnglibconf.h"
#endif

/* Local renames may change non-exported API functions from png.h */
#if defined(PNG_PREFIX) && !defined(PNGPREFIX_H)
#  include "pngprefix.h"
#endif

#ifdef PNG_USER_CONFIG
#  include "pngusr.h"
   /* These should have been defined in pngusr.h */
#  ifndef PNG_USER_PRIVATEBUILD
#    define PNG_USER_PRIVATEBUILD "Custom libpng build"
#  endif
#  ifndef PNG_USER_DLLFNAME_POSTFIX
#    define PNG_USER_DLLFNAME_POSTFIX "Cb"
#  endif
#endif

/* Compile time options.
 * =====================
 * In a multi-arch build the compiler may compile the code several times for the
 * same object module, producing different binaries for different architectures.
 * When this happens configure-time setting of the target host options cannot be
 * done and this interferes with the handling of the ARM NEON optimizations, and
 * possibly other similar optimizations.  Put additional tests here; in general
 * this is needed when the same option can be changed at both compile time and
 * run time depending on the target OS (i.e. iOS vs Android.)
 *
 * NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
 * this is not possible with certain compilers (Oracle SUN OS CC), as a result
 * it is necessary to ensure that all extern functions that *might* be used
 * regardless of $(CFLAGS) get declared in this file.  The test on __ARM_NEON__
 * below is one example of this behavior because it is controlled by the
 * presence or not of -mfpu=neon on the GCC command line, it is possible to do
 * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
 * do this.
 */
#ifndef PNG_ARM_NEON_OPT
   /* ARM NEON optimizations are being controlled by the compiler settings,
    * typically the target FPU.  If the FPU has been set to NEON (-mfpu=neon
    * with GCC) then the compiler will define __ARM_NEON__ and we can rely
    * unconditionally on NEON instructions not crashing, otherwise we must
    * disable use of NEON instructions.
    *
    * NOTE: at present these optimizations depend on 'ALIGNED_MEMORY', so they
    * can only be turned on automatically if that is supported too.  If
    * PNG_ARM_NEON_OPT is set in CPPFLAGS (to >0) then arm/arm_init.c will fail
    * to compile with an appropriate #error if ALIGNED_MEMORY has been turned
    * off.
    *
    * Note that gcc-4.9 defines __ARM_NEON instead of the deprecated
    * __ARM_NEON__, so we check both variants.
    *
    * To disable ARM_NEON optimizations entirely, and skip compiling the
    * associated assembler code, pass --enable-arm-neon=no to configure
    * or put -DPNG_ARM_NEON_OPT=0 in CPPFLAGS.
    */
#  if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
   defined(PNG_ALIGNED_MEMORY_SUPPORTED)
#     define PNG_ARM_NEON_OPT 2
#  else
#     define PNG_ARM_NEON_OPT 0
#  endif
#endif

#if PNG_ARM_NEON_OPT > 0
   /* NEON optimizations are to be at least considered by libpng, so enable the
    * callbacks to do this.
    */
#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon

   /* By default the 'intrinsics' code in arm/filter_neon_intrinsics.c is used
    * if possible - if __ARM_NEON__ is set and the compiler version is not known
    * to be broken.  This is controlled by PNG_ARM_NEON_IMPLEMENTATION which can
    * be:
    *
    *    1  The intrinsics code (the default with __ARM_NEON__)
    *    2  The hand coded assembler (the default without __ARM_NEON__)
    *
    * It is possible to set PNG_ARM_NEON_IMPLEMENTATION in CPPFLAGS, however
    * this is *NOT* supported and may cease to work even after a minor revision
    * to libpng.  It *is* valid to do this for testing purposes, e.g. speed
    * testing or a new compiler, but the results should be communicated to the
    * libpng implementation list for incorporation in the next minor release.
    */
#  ifndef PNG_ARM_NEON_IMPLEMENTATION
#     if defined(__ARM_NEON__) || defined(__ARM_NEON)
#        if defined(__clang__)
            /* At present it is unknown by the libpng developers which versions
             * of clang support the intrinsics, however some or perhaps all
             * versions do not work with the assembler so this may be
             * irrelevant, so just use the default (do nothing here.)
             */
#        elif defined(__GNUC__)
            /* GCC 4.5.4 NEON support is known to be broken.  4.6.3 is known to
             * work, so if this *is* GCC, or G++, look for a version >4.5
             */
#           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
#              define PNG_ARM_NEON_IMPLEMENTATION 2
#           endif /* no GNUC support */
#        endif /* __GNUC__ */
#     else /* !defined __ARM_NEON__ */
         /* The 'intrinsics' code simply won't compile without this -mfpu=neon:
          */
#        define PNG_ARM_NEON_IMPLEMENTATION 2
#     endif /* __ARM_NEON__ */
#  endif /* !PNG_ARM_NEON_IMPLEMENTATION */

#  ifndef PNG_ARM_NEON_IMPLEMENTATION
      /* Use the intrinsics code by default. */
#     define PNG_ARM_NEON_IMPLEMENTATION 1
#  endif
#endif /* PNG_ARM_NEON_OPT > 0 */

#ifndef PNG_MIPS_MSA_OPT
#  if defined(__mips_msa) && (__mips_isa_rev >= 5) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
#     define PNG_MIPS_MSA_OPT 2
#  else
#     define PNG_MIPS_MSA_OPT 0
#  endif
#endif

#ifndef PNG_POWERPC_VSX_OPT
#  if defined(__PPC64__) && defined(__ALTIVEC__) && defined(__VSX__)
#     define PNG_POWERPC_VSX_OPT 2
#  else
#     define PNG_POWERPC_VSX_OPT 0
#  endif
#endif

#ifndef PNG_INTEL_SSE_OPT
#   ifdef PNG_INTEL_SSE
      /* Only check for SSE if the build configuration has been modified to
       * enable SSE optimizations.  This means that these optimizations will
       * be off by default.  See contrib/intel for more details.
       */
#     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
#         define PNG_INTEL_SSE_OPT 1
#      else
#         define PNG_INTEL_SSE_OPT 0
#      endif
#   else
#      define PNG_INTEL_SSE_OPT 0
#   endif
#endif

#if PNG_INTEL_SSE_OPT > 0
#   ifndef PNG_INTEL_SSE_IMPLEMENTATION
#      if defined(__SSE4_1__) || defined(__AVX__)
          /* We are not actually using AVX, but checking for AVX is the best
             way we can detect SSE4.1 and SSSE3 on MSVC.
          */
#         define PNG_INTEL_SSE_IMPLEMENTATION 3
#      elif defined(__SSSE3__)
#         define PNG_INTEL_SSE_IMPLEMENTATION 2
#      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
#         define PNG_INTEL_SSE_IMPLEMENTATION 1
#      else
#         define PNG_INTEL_SSE_IMPLEMENTATION 0
#      endif
#   endif

#   if PNG_INTEL_SSE_IMPLEMENTATION > 0
#      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
#   endif
#else
#   define PNG_INTEL_SSE_IMPLEMENTATION 0
#endif

#if PNG_MIPS_MSA_OPT > 0
#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_msa
#  ifndef PNG_MIPS_MSA_IMPLEMENTATION
#     if defined(__mips_msa)
#        if defined(__clang__)
#        elif defined(__GNUC__)
#           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
#              define PNG_MIPS_MSA_IMPLEMENTATION 2
#           endif /* no GNUC support */
#        endif /* __GNUC__ */
#     else /* !defined __mips_msa */
#        define PNG_MIPS_MSA_IMPLEMENTATION 2
#     endif /* __mips_msa */
#  endif /* !PNG_MIPS_MSA_IMPLEMENTATION */

#  ifndef PNG_MIPS_MSA_IMPLEMENTATION
#     define PNG_MIPS_MSA_IMPLEMENTATION 1
#  endif
#endif /* PNG_MIPS_MSA_OPT > 0 */

#if PNG_POWERPC_VSX_OPT > 0
#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_vsx
#  define PNG_POWERPC_VSX_IMPLEMENTATION 1
#endif


/* Is this a build of a DLL where compilation of the object modules requires
 * different preprocessor settings to those required for a simple library?  If
 * so PNG_BUILD_DLL must be set.
 *
 * If libpng is used inside a DLL but that DLL does not export the libpng APIs
 * PNG_BUILD_DLL must not be set.  To avoid the code below kicking in build a
 * static library of libpng then link the DLL against that.
 */
#ifndef PNG_BUILD_DLL
#  ifdef DLL_EXPORT
      /* This is set by libtool when files are compiled for a DLL; libtool
       * always compiles twice, even on systems where it isn't necessary.  Set
       * PNG_BUILD_DLL in case it is necessary:
       */
#     define PNG_BUILD_DLL
#  else
#     ifdef _WINDLL
         /* This is set by the Microsoft Visual Studio IDE in projects that
          * build a DLL.  It can't easily be removed from those projects (it
          * isn't visible in the Visual Studio UI) so it is a fairly reliable
          * indication that PNG_IMPEXP needs to be set to the DLL export
          * attributes.
          */
#        define PNG_BUILD_DLL
#     else
#        ifdef __DLL__
            /* This is set by the Borland C system when compiling for a DLL
             * (as above.)
             */
#           define PNG_BUILD_DLL
#        else
            /* Add additional compiler cases here. */
#        endif
#     endif
#  endif
#endif /* Setting PNG_BUILD_DLL if required */

/* See pngconf.h for more details: the builder of the library may set this on
 * the command line to the right thing for the specific compilation system or it
 * may be automagically set above (at present we know of no system where it does
 * need to be set on the command line.)
 *
 * PNG_IMPEXP must be set here when building the library to prevent pngconf.h
 * setting it to the "import" setting for a DLL build.
 */
#ifndef PNG_IMPEXP
#  ifdef PNG_BUILD_DLL
#     define PNG_IMPEXP PNG_DLL_EXPORT
#  else
      /* Not building a DLL, or the DLL doesn't require specific export
       * definitions.
       */
#     define PNG_IMPEXP
#  endif
#endif

/* No warnings for private or deprecated functions in the build: */
#ifndef PNG_DEPRECATED
#  define PNG_DEPRECATED
#endif
#ifndef PNG_PRIVATE
#  define PNG_PRIVATE
#endif

/* Symbol preprocessing support.
 *
 * To enable listing global, but internal, symbols the following macros should
 * always be used to declare an extern data or function object in this file.
 */
#ifndef PNG_INTERNAL_DATA
#  define PNG_INTERNAL_DATA(type, name, array) PNG_LINKAGE_DATA type name array
#endif

#ifndef PNG_INTERNAL_FUNCTION
#  define PNG_INTERNAL_FUNCTION(type, name, args, attributes)\
      PNG_LINKAGE_FUNCTION PNG_FUNCTION(type, name, args, PNG_EMPTY attributes)
#endif

#ifndef PNG_INTERNAL_CALLBACK
#  define PNG_INTERNAL_CALLBACK(type, name, args, attributes)\
      PNG_LINKAGE_CALLBACK PNG_FUNCTION(type, (PNGCBAPI name), args,\
         PNG_EMPTY attributes)
#endif

/* If floating or fixed point APIs are disabled they may still be compiled
 * internally.  To handle this make sure they are declared as the appropriate
 * internal extern function (otherwise the symbol prefixing stuff won't work and
 * the functions will be used without definitions.)
 *
 * NOTE: although all the API functions are declared here they are not all
 * actually built!  Because the declarations are still made it is necessary to
 * fake out types that they depend on.
 */
#ifndef PNG_FP_EXPORT
#  ifndef PNG_FLOATING_POINT_SUPPORTED
#     define PNG_FP_EXPORT(ordinal, type, name, args)\
         PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
#     ifndef PNG_VERSION_INFO_ONLY
         typedef struct png_incomplete png_double;
         typedef png_double*           png_doublep;
         typedef const png_double*     png_const_doublep;
         typedef png_double**          png_doublepp;
#     endif
#  endif
#endif
#ifndef PNG_FIXED_EXPORT
#  ifndef PNG_FIXED_POINT_SUPPORTED
#     define PNG_FIXED_EXPORT(ordinal, type, name, args)\
         PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
#  endif
#endif

#include "png.h"

/* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
#ifndef PNG_DLL_EXPORT
#  define PNG_DLL_EXPORT
#endif

/* This is a global switch to set the compilation for an installed system
 * (a release build).  It can be set for testing debug builds to ensure that
 * they will compile when the build type is switched to RC or STABLE, the
 * default is just to use PNG_LIBPNG_BUILD_BASE_TYPE.  Set this in CPPFLAGS
 * with either:
 *
 *   -DPNG_RELEASE_BUILD Turns on the release compile path
 *   -DPNG_RELEASE_BUILD=0 Turns it off
 * or in your pngusr.h with
 *   #define PNG_RELEASE_BUILD=1 Turns on the release compile path
 *   #define PNG_RELEASE_BUILD=0 Turns it off
 */
#ifndef PNG_RELEASE_BUILD
#  define PNG_RELEASE_BUILD (PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC)
#endif

/* SECURITY and SAFETY:
 *
 * libpng is built with support for internal limits on image dimensions and
 * memory usage.  These are documented in scripts/pnglibconf.dfa of the
 * source and recorded in the machine generated header file pnglibconf.h.
 */

/* If you are running on a machine where you cannot allocate more
 * than 64K of memory at once, uncomment this.  While libpng will not
 * normally need that much memory in a chunk (unless you load up a very
 * large file), zlib needs to know how big of a chunk it can use, and
 * libpng thus makes sure to check any memory allocation to verify it
 * will fit into memory.
 *
 * zlib provides 'MAXSEG_64K' which, if defined, indicates the
 * same limit and pngconf.h (already included) sets the limit
 * if certain operating systems are detected.
 */
#if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
#  define PNG_MAX_MALLOC_64K
#endif

#ifndef PNG_UNUSED
/* Unused formal parameter warnings are silenced using the following macro
 * which is expected to have no bad effects on performance (optimizing
 * compilers will probably remove it entirely).  Note that if you replace
 * it with something other than whitespace, you must include the terminating
 * semicolon.
 */
#  define PNG_UNUSED(param) (void)param;
#endif

/* Just a little check that someone hasn't tried to define something
 * contradictory.
 */
#if (PNG_ZBUF_SIZE > 65536L) && defined(PNG_MAX_MALLOC_64K)
#  undef PNG_ZBUF_SIZE
#  define PNG_ZBUF_SIZE 65536L
#endif

/* If warnings or errors are turned off the code is disabled or redirected here.
 * From 1.5.4 functions have been added to allow very limited formatting of
 * error and warning messages - this code will also be disabled here.
 */
#ifdef PNG_WARNINGS_SUPPORTED
#  define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
#else
#  define png_warning_parameter(p,number,string) ((void)0)
#  define png_warning_parameter_unsigned(p,number,format,value) ((void)0)
#  define png_warning_parameter_signed(p,number,format,value) ((void)0)
#  define png_formatted_warning(pp,p,message) ((void)(pp))
#  define PNG_WARNING_PARAMETERS(p)
#endif
#ifndef PNG_ERROR_TEXT_SUPPORTED
#  define png_fixed_error(s1,s2) png_err(s1)
#endif

/* Some fixed point APIs are still required even if not exported because
 * they get used by the corresponding floating point APIs.  This magic
 * deals with this:
 */
#ifdef PNG_FIXED_POINT_SUPPORTED
#  define PNGFAPI PNGAPI
#else
#  define PNGFAPI /* PRIVATE */
#endif

#ifndef PNG_VERSION_INFO_ONLY
/* Other defines specific to compilers can go here.  Try to keep
 * them inside an appropriate ifdef/endif pair for portability.
 */

/* C allows up-casts from (void*) to any pointer and (const void*) to any
 * pointer to a const object.  C++ regards this as a type error and requires an
 * explicit, static, cast and provides the static_cast<> rune to ensure that
 * const is not cast away.
 */
#ifdef __cplusplus
#  define png_voidcast(type, value) static_cast<type>(value)
#  define png_constcast(type, value) const_cast<type>(value)
#  define png_aligncast(type, value) \
   static_cast<type>(static_cast<void*>(value))
#  define png_aligncastconst(type, value) \
   static_cast<type>(static_cast<const void*>(value))
#else
#  define png_voidcast(type, value) (value)
#  ifdef _WIN64
#     ifdef __GNUC__
         typedef unsigned long long png_ptruint;
#     else
         typedef unsigned __int64 png_ptruint;
#     endif
#  else
      typedef unsigned long png_ptruint;
#  endif
#  define png_constcast(type, value) ((type)(png_ptruint)(const void*)(value))
#  define png_aligncast(type, value) ((void*)(value))
#  define png_aligncastconst(type, value) ((const void*)(value))
#endif /* __cplusplus */

#if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
    defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
   /* png.c requires the following ANSI-C constants if the conversion of
    * floating point to ASCII is implemented therein:
    *
    *  DBL_DIG  Maximum number of decimal digits (can be set to any constant)
    *  DBL_MIN  Smallest normalized fp number (can be set to an arbitrary value)
    *  DBL_MAX  Maximum floating point number (can be set to an arbitrary value)
    */
#  include <float.h>

#  if (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
    defined(THINK_C) || defined(__SC__) || defined(TARGET_OS_MAC)
   /* We need to check that <math.h> hasn't already been included earlier
    * as it seems it doesn't agree with <fp.h>, yet we should really use
    * <fp.h> if possible.
    */
#    if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
#      include <fp.h>
#    endif
#  else
#    include <math.h>
#  endif
#  if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
   /* Amiga SAS/C: We must include builtin FPU functions when compiling using
    * MATH=68881
    */
#    include <m68881.h>
#  endif
#endif

/* This provides the non-ANSI (far) memory allocation routines. */
#if defined(__TURBOC__) && defined(__MSDOS__)
#  include <mem.h>
#  include <alloc.h>
#endif

#if defined(WIN32) || defined(_Windows) || defined(_WINDOWS) || \
    defined(_WIN32) || defined(__WIN32__)
#  include <windows.h>  /* defines _WINDOWS_ macro */
#endif
#endif /* PNG_VERSION_INFO_ONLY */

/* Moved here around 1.5.0beta36 from pngconf.h */
/* Users may want to use these so they are not private.  Any library
 * functions that are passed far data must be model-independent.
 */

/* Memory model/platform independent fns */
#ifndef PNG_ABORT
#  ifdef _WINDOWS_
#    define PNG_ABORT() ExitProcess(0)
#  else
#    define PNG_ABORT() abort()
#  endif
#endif

/* These macros may need to be architecture dependent. */
#define PNG_ALIGN_NONE   0 /* do not use data alignment */
#define PNG_ALIGN_ALWAYS 1 /* assume unaligned accesses are OK */
#ifdef offsetof
#  define PNG_ALIGN_OFFSET 2 /* use offsetof to determine alignment */
#else
#  define PNG_ALIGN_OFFSET -1 /* prevent the use of this */
#endif
#define PNG_ALIGN_SIZE   3 /* use sizeof to determine alignment */

#ifndef PNG_ALIGN_TYPE
   /* Default to using aligned access optimizations and requiring alignment to a
    * multiple of the data type size.  Override in a compiler specific fashion
    * if necessary by inserting tests here:
    */
#  define PNG_ALIGN_TYPE PNG_ALIGN_SIZE
#endif

#if PNG_ALIGN_TYPE == PNG_ALIGN_SIZE
   /* This is used because in some compiler implementations non-aligned
    * structure members are supported, so the offsetof approach below fails.
    * Set PNG_ALIGN_SIZE=0 for compiler combinations where unaligned access
    * is good for performance.  Do not do this unless you have tested the result
    * and understand it.
    */
#  define png_alignof(type) (sizeof (type))
#else
#  if PNG_ALIGN_TYPE == PNG_ALIGN_OFFSET
#     define png_alignof(type) offsetof(struct{char c; type t;}, t)
#  else
#     if PNG_ALIGN_TYPE == PNG_ALIGN_ALWAYS
#        define png_alignof(type) (1)
#     endif
      /* Else leave png_alignof undefined to prevent use thereof */
#  endif
#endif

/* This implicitly assumes alignment is always to a power of 2. */
#ifdef png_alignof
#  define png_isaligned(ptr, type)\
   (((type)((const char*)ptr-(const char*)0) & \
   (type)(png_alignof(type)-1)) == 0)
#else
#  define png_isaligned(ptr, type) 0
#endif

/* End of memory model/platform independent support */
/* End of 1.5.0beta36 move from pngconf.h */

/* CONSTANTS and UTILITY MACROS
 * These are used internally by libpng and not exposed in the API
 */

/* Various modes of operation.  Note that after an init, mode is set to
 * zero automatically when the structure is created.  Three of these
 * are defined in png.h because they need to be visible to applications
 * that call png_set_unknown_chunk().
 */
/* #define PNG_HAVE_IHDR            0x01U (defined in png.h) */
/* #define PNG_HAVE_PLTE            0x02U (defined in png.h) */
#define PNG_HAVE_IDAT               0x04U
/* #define PNG_AFTER_IDAT           0x08U (defined in png.h) */
#define PNG_HAVE_IEND               0x10U
                   /*               0x20U (unused) */
                   /*               0x40U (unused) */
                   /*               0x80U (unused) */
#define PNG_HAVE_CHUNK_HEADER      0x100U
#define PNG_WROTE_tIME             0x200U
#define PNG_WROTE_INFO_BEFORE_PLTE 0x400U
#define PNG_BACKGROUND_IS_GRAY     0x800U
#define PNG_HAVE_PNG_SIGNATURE    0x1000U
#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000U /* Have another chunk after IDAT */
                   /*             0x4000U (unused) */
#define PNG_IS_READ_STRUCT        0x8000U /* Else is a write struct */
#ifdef PNG_APNG_SUPPORTED
#define PNG_HAVE_acTL            0x10000U
#define PNG_HAVE_fcTL            0x20000U
#endif

/* Flags for the transformations the PNG library does on the image data */
#define PNG_BGR                 0x0001U
#define PNG_INTERLACE           0x0002U
#define PNG_PACK                0x0004U
#define PNG_SHIFT               0x0008U
#define PNG_SWAP_BYTES          0x0010U
#define PNG_INVERT_MONO         0x0020U
#define PNG_QUANTIZE            0x0040U
#define PNG_COMPOSE             0x0080U    /* Was PNG_BACKGROUND */
#define PNG_BACKGROUND_EXPAND   0x0100U
#define PNG_EXPAND_16           0x0200U    /* Added to libpng 1.5.2 */
#define PNG_16_TO_8             0x0400U    /* Becomes 'chop' in 1.5.4 */
#define PNG_RGBA                0x0800U
#define PNG_EXPAND              0x1000U
#define PNG_GAMMA               0x2000U
#define PNG_GRAY_TO_RGB         0x4000U
#define PNG_FILLER              0x8000U
#define PNG_PACKSWAP           0x10000U
#define PNG_SWAP_ALPHA         0x20000U
#define PNG_STRIP_ALPHA        0x40000U
#define PNG_INVERT_ALPHA       0x80000U
#define PNG_USER_TRANSFORM    0x100000U
#define PNG_RGB_TO_GRAY_ERR   0x200000U
#define PNG_RGB_TO_GRAY_WARN  0x400000U
#define PNG_RGB_TO_GRAY       0x600000U /* two bits, RGB_TO_GRAY_ERR|WARN */
#define PNG_ENCODE_ALPHA      0x800000U /* Added to libpng-1.5.4 */
#define PNG_ADD_ALPHA        0x1000000U /* Added to libpng-1.2.7 */
#define PNG_EXPAND_tRNS      0x2000000U /* Added to libpng-1.2.9 */
#define PNG_SCALE_16_TO_8    0x4000000U /* Added to libpng-1.5.4 */
                       /*    0x8000000U unused */
                       /*   0x10000000U unused */
                       /*   0x20000000U unused */
                       /*   0x40000000U unused */
/* Flags for png_create_struct */
#define PNG_STRUCT_PNG   0x0001U
#define PNG_STRUCT_INFO  0x0002U

/* Flags for the png_ptr->flags rather than declaring a byte for each one */
#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001U
#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002U /* Added to libpng-1.6.0 */
                                  /*      0x0004U    unused */
#define PNG_FLAG_ZSTREAM_ENDED            0x0008U /* Added to libpng-1.6.0 */
                                  /*      0x0010U    unused */
                                  /*      0x0020U    unused */
#define PNG_FLAG_ROW_INIT                 0x0040U
#define PNG_FLAG_FILLER_AFTER             0x0080U
#define PNG_FLAG_CRC_ANCILLARY_USE        0x0100U
#define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200U
#define PNG_FLAG_CRC_CRITICAL_USE         0x0400U
#define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800U
#define PNG_FLAG_ASSUME_sRGB              0x1000U /* Added to libpng-1.5.4 */
#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000U /* Added to libpng-1.5.4 */
#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000U /* Added to libpng-1.5.4 */
/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000U */
/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000U */
#define PNG_FLAG_LIBRARY_MISMATCH        0x20000U
#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000U
#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000U
#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000U /* Added to libpng-1.4.0 */
#define PNG_FLAG_APP_WARNINGS_WARN      0x200000U /* Added to libpng-1.6.0 */
#define PNG_FLAG_APP_ERRORS_WARN        0x400000U /* Added to libpng-1.6.0 */
                                  /*    0x800000U    unused */
                                  /*   0x1000000U    unused */
                                  /*   0x2000000U    unused */
                                  /*   0x4000000U    unused */
                                  /*   0x8000000U    unused */
                                  /*  0x10000000U    unused */
                                  /*  0x20000000U    unused */
                                  /*  0x40000000U    unused */

#define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                     PNG_FLAG_CRC_ANCILLARY_NOWARN)

#define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
                                     PNG_FLAG_CRC_CRITICAL_IGNORE)

#define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
                                     PNG_FLAG_CRC_CRITICAL_MASK)

/* Save typing and make code easier to understand */

#define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
   abs((int)((c1).green) - (int)((c2).green)) + \
   abs((int)((c1).blue) - (int)((c2).blue)))

/* Added to libpng-1.6.0: scale a 16-bit value in the range 0..65535 to 0..255
 * by dividing by 257 *with rounding*.  This macro is exact for the given range.
 * See the discourse in pngrtran.c png_do_scale_16_to_8.  The values in the
 * macro were established by experiment (modifying the added value).  The macro
 * has a second variant that takes a value already scaled by 255 and divides by
 * 65535 - this has a maximum error of .502.  Over the range 0..65535*65535 it
 * only gives off-by-one errors and only for 0.5% (1 in 200) of the values.
 */
#define PNG_DIV65535(v24) (((v24) + 32895) >> 16)
#define PNG_DIV257(v16) PNG_DIV65535((png_uint_32)(v16) * 255)

/* Added to libpng-1.2.6 JB */
#define PNG_ROWBYTES(pixel_bits, width) \
    ((pixel_bits) >= 8 ? \
    ((size_t)(width) * (((size_t)(pixel_bits)) >> 3)) : \
    (( ((size_t)(width) * ((size_t)(pixel_bits))) + 7) >> 3) )

/* This returns the number of trailing bits in the last byte of a row, 0 if the
 * last byte is completely full of pixels.  It is, in principle, (pixel_bits x
 * width) % 8, but that would overflow for large 'width'.  The second macro is
 * the same except that it returns the number of unused bits in the last byte;
 * (8-TRAILBITS), but 0 when TRAILBITS is 0.
 *
 * NOTE: these macros are intended to be self-evidently correct and never
 * overflow on the assumption that pixel_bits is in the range 0..255.  The
 * arguments are evaluated only once and they can be signed (e.g. as a result of
 * the integral promotions).  The result of the expression always has type
 * (png_uint_32), however the compiler always knows it is in the range 0..7.
 */
#define PNG_TRAILBITS(pixel_bits, width) \
    (((pixel_bits) * ((width) % (png_uint_32)8)) % 8)

#define PNG_PADBITS(pixel_bits, width) \
    ((8 - PNG_TRAILBITS(pixel_bits, width)) % 8)

/* PNG_OUT_OF_RANGE returns true if value is outside the range
 * ideal-delta..ideal+delta.  Each argument is evaluated twice.
 * "ideal" and "delta" should be constants, normally simple
 * integers, "value" a variable. Added to libpng-1.2.6 JB
 */
#define PNG_OUT_OF_RANGE(value, ideal, delta) \
   ( (value) < (ideal)-(delta) || (value) > (ideal)+(delta) )

/* Conversions between fixed and floating point, only defined if
 * required (to make sure the code doesn't accidentally use float
 * when it is supposedly disabled.)
 */
#ifdef PNG_FLOATING_POINT_SUPPORTED
/* The floating point conversion can't overflow, though it can and
 * does lose accuracy relative to the original fixed point value.
 * In practice this doesn't matter because png_fixed_point only
 * stores numbers with very low precision.  The png_ptr and s
 * arguments are unused by default but are there in case error
 * checking becomes a requirement.
 */
#define png_float(png_ptr, fixed, s) (.00001 * (fixed))

/* The fixed point conversion performs range checking and evaluates
 * its argument multiple times, so must be used with care.  The
 * range checking uses the PNG specification values for a signed
 * 32-bit fixed point value except that the values are deliberately
 * rounded-to-zero to an integral value - 21474 (21474.83 is roughly
 * (2^31-1) * 100000). 's' is a string that describes the value being
 * converted.
 *
 * NOTE: this macro will raise a png_error if the range check fails,
 * therefore it is normally only appropriate to use this on values
 * that come from API calls or other sources where an out of range
 * error indicates a programming error, not a data error!
 *
 * NOTE: by default this is off - the macro is not used - because the
 * function call saves a lot of code.
 */
#ifdef PNG_FIXED_POINT_MACRO_SUPPORTED
#define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
    ((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
#endif
/* else the corresponding function is defined below, inside the scope of the
 * cplusplus test.
 */
#endif

/* Constants for known chunk types.  If you need to add a chunk, define the name
 * here.  For historical reasons these constants have the form png_<name>; i.e.
 * the prefix is lower case.  Please use decimal values as the parameters to
 * match the ISO PNG specification and to avoid relying on the C locale
 * interpretation of character values.
 *
 * Prior to 1.5.6 these constants were strings, as of 1.5.6 png_uint_32 values
 * are computed and a new macro (PNG_STRING_FROM_CHUNK) added to allow a string
 * to be generated if required.
 *
 * PNG_32b correctly produces a value shifted by up to 24 bits, even on
 * architectures where (int) is only 16 bits.
 */
#define PNG_32b(b,s) ((png_uint_32)(b) << (s))
#define PNG_U32(b1,b2,b3,b4) \
   (PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0))

/* Constants for known chunk types.
 *
 * MAINTAINERS: If you need to add a chunk, define the name here.
 * For historical reasons these constants have the form png_<name>; i.e.
 * the prefix is lower case.  Please use decimal values as the parameters to
 * match the ISO PNG specification and to avoid relying on the C locale
 * interpretation of character values.  Please keep the list sorted.
 *
 * Notice that PNG_U32 is used to define a 32-bit value for the 4 byte chunk
 * type.  In fact the specification does not express chunk types this way,
 * however using a 32-bit value means that the chunk type can be read from the
 * stream using exactly the same code as used for a 32-bit unsigned value and
 * can be examined far more efficiently (using one arithmetic compare).
 *
 * Prior to 1.5.6 the chunk type constants were expressed as C strings.  The
 * libpng API still uses strings for 'unknown' chunks and a macro,
 * PNG_STRING_FROM_CHUNK, allows a string to be generated if required.  Notice
 * that for portable code numeric values must still be used; the string "IHDR"
 * is not portable and neither is PNG_U32('I', 'H', 'D', 'R').
 *
 * In 1.7.0 the definitions will be made public in png.h to avoid having to
 * duplicate the same definitions in application code.
 */
#define png_IDAT PNG_U32( 73,  68,  65,  84)
#define png_IEND PNG_U32( 73,  69,  78,  68)
#define png_IHDR PNG_U32( 73,  72,  68,  82)
#define png_PLTE PNG_U32( 80,  76,  84,  69)
#define png_bKGD PNG_U32( 98,  75,  71,  68)
#define png_cHRM PNG_U32( 99,  72,  82,  77)
#define png_eXIf PNG_U32(101,  88,  73, 102) /* registered July 2017 */
#define png_fRAc PNG_U32(102,  82,  65,  99) /* registered, not defined */
#define png_gAMA PNG_U32(103,  65,  77,  65)
#define png_gIFg PNG_U32(103,  73,  70, 103)
#define png_gIFt PNG_U32(103,  73,  70, 116) /* deprecated */
#define png_gIFx PNG_U32(103,  73,  70, 120)
#define png_hIST PNG_U32(104,  73,  83,  84)
#define png_iCCP PNG_U32(105,  67,  67,  80)
#define png_iTXt PNG_U32(105,  84,  88, 116)
#define png_oFFs PNG_U32(111,  70,  70, 115)
#define png_pCAL PNG_U32(112,  67,  65,  76)
#define png_pHYs PNG_U32(112,  72,  89, 115)
#define png_sBIT PNG_U32(115,  66,  73,  84)
#define png_sCAL PNG_U32(115,  67,  65,  76)
#define png_sPLT PNG_U32(115,  80,  76,  84)
#define png_sRGB PNG_U32(115,  82,  71,  66)
#define png_sTER PNG_U32(115,  84,  69,  82)
#define png_tEXt PNG_U32(116,  69,  88, 116)
#define png_tIME PNG_U32(116,  73,  77,  69)
#define png_tRNS PNG_U32(116,  82,  78,  83)
#define png_zTXt PNG_U32(122,  84,  88, 116)

#ifdef PNG_APNG_SUPPORTED
#define png_acTL PNG_U32( 97,  99,  84,  76)
#define png_fcTL PNG_U32(102,  99,  84,  76)
#define png_fdAT PNG_U32(102, 100,  65,  84)

/* For png_struct.apng_flags: */
#define PNG_FIRST_FRAME_HIDDEN       0x0001U
#define PNG_APNG_APP                 0x0002U
#endif

/* The following will work on (signed char*) strings, whereas the get_uint_32
 * macro will fail on top-bit-set values because of the sign extension.
 */
#define PNG_CHUNK_FROM_STRING(s)\
   PNG_U32(0xff & (s)[0], 0xff & (s)[1], 0xff & (s)[2], 0xff & (s)[3])

/* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
 * signed and the argument is a (char[])  This macro will fail miserably on
 * systems where (char) is more than 8 bits.
 */
#define PNG_STRING_FROM_CHUNK(s,c)\
   (void)(((char*)(s))[0]=(char)(((c)>>24) & 0xff), \
   ((char*)(s))[1]=(char)(((c)>>16) & 0xff),\
   ((char*)(s))[2]=(char)(((c)>>8) & 0xff), \
   ((char*)(s))[3]=(char)((c & 0xff)))

/* Do the same but terminate with a null character. */
#define PNG_CSTRING_FROM_CHUNK(s,c)\
   (void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)

/* Test on flag values as defined in the spec (section 5.4): */
#define PNG_CHUNK_ANCILLARY(c)   (1 & ((c) >> 29))
#define PNG_CHUNK_CRITICAL(c)     (!PNG_CHUNK_ANCILLARY(c))
#define PNG_CHUNK_PRIVATE(c)      (1 & ((c) >> 21))
#define PNG_CHUNK_RESERVED(c)     (1 & ((c) >> 13))
#define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >>  5))

/* Gamma values (new at libpng-1.5.4): */
#define PNG_GAMMA_MAC_OLD 151724  /* Assume '1.8' is really 2.2/1.45! */
#define PNG_GAMMA_MAC_INVERSE 65909
#define PNG_GAMMA_sRGB_INVERSE 45455

/* Almost everything below is C specific; the #defines above can be used in
 * non-C code (so long as it is C-preprocessed) the rest of this stuff cannot.
 */
#ifndef PNG_VERSION_INFO_ONLY

#include "pngstruct.h"
#include "pnginfo.h"

/* Validate the include paths - the include path used to generate pnglibconf.h
 * must match that used in the build, or we must be using pnglibconf.h.prebuilt:
 */
#if PNG_ZLIB_VERNUM != 0 && PNG_ZLIB_VERNUM != ZLIB_VERNUM
#  error ZLIB_VERNUM != PNG_ZLIB_VERNUM \
      "-I (include path) error: see the notes in pngpriv.h"
   /* This means that when pnglibconf.h was built the copy of zlib.h that it
    * used is not the same as the one being used here.  Because the build of
    * libpng makes decisions to use inflateInit2 and inflateReset2 based on the
    * zlib version number and because this affects handling of certain broken
    * PNG files the -I directives must match.
    *
    * The most likely explanation is that you passed a -I in CFLAGS. This will
    * not work; all the preprocessor directives and in particular all the -I
    * directives must be in CPPFLAGS.
    */
#endif

/* This is used for 16-bit gamma tables -- only the top level pointers are
 * const; this could be changed:
 */
typedef const png_uint_16p * png_const_uint_16pp;

/* Added to libpng-1.5.7: sRGB conversion tables */
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_table, [256]);
   /* Convert from an sRGB encoded value 0..255 to a 16-bit linear value,
    * 0..65535.  This table gives the closest 16-bit answers (no errors).
    */
#endif

PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_base, [512]);
PNG_INTERNAL_DATA(const png_byte, png_sRGB_delta, [512]);

#define PNG_sRGB_FROM_LINEAR(linear) \
  ((png_byte)(0xff & ((png_sRGB_base[(linear)>>15] \
   + ((((linear) & 0x7fff)*png_sRGB_delta[(linear)>>15])>>12)) >> 8)))
   /* Given a value 'linear' in the range 0..255*65535 calculate the 8-bit sRGB
    * encoded value with maximum error 0.646365.  Note that the input is not a
    * 16-bit value; it has been multiplied by 255! */
#endif /* SIMPLIFIED_READ/WRITE */


/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/* Internal functions; these are not exported from a DLL however because they
 * are used within several of the C source files they have to be C extern.
 *
 * All of these functions must be declared with PNG_INTERNAL_FUNCTION.
 */

/* Zlib support */
#define PNG_UNEXPECTED_ZLIB_RETURN (-7)
PNG_INTERNAL_FUNCTION(void, png_zstream_error,(png_structrp png_ptr, int ret),
   PNG_EMPTY);
   /* Used by the zlib handling functions to ensure that z_stream::msg is always
    * set before they return.
    */

#ifdef PNG_WRITE_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_free_buffer_list,(png_structrp png_ptr,
   png_compression_bufferp *list),PNG_EMPTY);
   /* Free the buffer list used by the compressed write code. */
#endif

#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
   !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
   (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
   defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
   (defined(PNG_sCAL_SUPPORTED) && \
   defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
PNG_INTERNAL_FUNCTION(png_fixed_point,png_fixed,(png_const_structrp png_ptr,
   double fp, png_const_charp text),PNG_EMPTY);
#endif

/* Check the user version string for compatibility, returns false if the version
 * numbers aren't compatible.
 */
PNG_INTERNAL_FUNCTION(int,png_user_version_check,(png_structrp png_ptr,
   png_const_charp user_png_ver),PNG_EMPTY);

/* Internal base allocator - no messages, NULL on failure to allocate.  This
 * does, however, call the application provided allocator and that could call
 * png_error (although that would be a bug in the application implementation.)
 */
PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_base,(png_const_structrp png_ptr,
   png_alloc_size_t size),PNG_ALLOCATED);

#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
   defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
/* Internal array allocator, outputs no error or warning messages on failure,
 * just returns NULL.
 */
PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_array,(png_const_structrp png_ptr,
   int nelements, size_t element_size),PNG_ALLOCATED);

/* The same but an existing array is extended by add_elements.  This function
 * also memsets the new elements to 0 and copies the old elements.  The old
 * array is not freed or altered.
 */
PNG_INTERNAL_FUNCTION(png_voidp,png_realloc_array,(png_const_structrp png_ptr,
   png_const_voidp array, int old_elements, int add_elements,
   size_t element_size),PNG_ALLOCATED);
#endif /* text, sPLT or unknown chunks */

/* Magic to create a struct when there is no struct to call the user supplied
 * memory allocators.  Because error handling has not been set up the memory
 * handlers can't safely call png_error, but this is an obscure and undocumented
 * restriction so libpng has to assume that the 'free' handler, at least, might
 * call png_error.
 */
PNG_INTERNAL_FUNCTION(png_structp,png_create_png_struct,
   (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
    png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn,
    png_free_ptr free_fn),PNG_ALLOCATED);

/* Free memory from internal libpng struct */
PNG_INTERNAL_FUNCTION(void,png_destroy_png_struct,(png_structrp png_ptr),
   PNG_EMPTY);

/* Free an allocated jmp_buf (always succeeds) */
PNG_INTERNAL_FUNCTION(void,png_free_jmpbuf,(png_structrp png_ptr),PNG_EMPTY);

/* Function to allocate memory for zlib.  PNGAPI is disallowed. */
PNG_INTERNAL_FUNCTION(voidpf,png_zalloc,(voidpf png_ptr, uInt items, uInt size),
   PNG_ALLOCATED);

/* Function to free memory for zlib.  PNGAPI is disallowed. */
PNG_INTERNAL_FUNCTION(void,png_zfree,(voidpf png_ptr, voidpf ptr),PNG_EMPTY);

/* Next four functions are used internally as callbacks.  PNGCBAPI is required
 * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3, changed to
 * PNGCBAPI at 1.5.0
 */

PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_read_data,(png_structp png_ptr,
    png_bytep data, size_t length),PNG_EMPTY);

#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_push_fill_buffer,(png_structp png_ptr,
    png_bytep buffer, size_t length),PNG_EMPTY);
#endif

PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_write_data,(png_structp png_ptr,
    png_bytep data, size_t length),PNG_EMPTY);

#ifdef PNG_WRITE_FLUSH_SUPPORTED
#  ifdef PNG_STDIO_SUPPORTED
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_flush,(png_structp png_ptr),
   PNG_EMPTY);
#  endif
#endif

/* Reset the CRC variable */
PNG_INTERNAL_FUNCTION(void,png_reset_crc,(png_structrp png_ptr),PNG_EMPTY);

/* Write the "data" buffer to whatever output you are using */
PNG_INTERNAL_FUNCTION(void,png_write_data,(png_structrp png_ptr,
    png_const_bytep data, size_t length),PNG_EMPTY);

/* Read and check the PNG file signature */
PNG_INTERNAL_FUNCTION(void,png_read_sig,(png_structrp png_ptr,
   png_inforp info_ptr),PNG_EMPTY);

/* Read the chunk header (length + type name) */
PNG_INTERNAL_FUNCTION(png_uint_32,png_read_chunk_header,(png_structrp png_ptr),
   PNG_EMPTY);

/* Read data from whatever input you are using into the "data" buffer */
PNG_INTERNAL_FUNCTION(void,png_read_data,(png_structrp png_ptr, png_bytep data,
    size_t length),PNG_EMPTY);

/* Read bytes into buf, and update png_ptr->crc */
PNG_INTERNAL_FUNCTION(void,png_crc_read,(png_structrp png_ptr, png_bytep buf,
    png_uint_32 length),PNG_EMPTY);

/* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
PNG_INTERNAL_FUNCTION(int,png_crc_finish,(png_structrp png_ptr,
   png_uint_32 skip),PNG_EMPTY);

/* Read the CRC from the file and compare it to the libpng calculated CRC */
PNG_INTERNAL_FUNCTION(int,png_crc_error,(png_structrp png_ptr),PNG_EMPTY);

/* Calculate the CRC over a section of data.  Note that we are only
 * passing a maximum of 64K on systems that have this as a memory limit,
 * since this is the maximum buffer size we can specify.
 */
PNG_INTERNAL_FUNCTION(void,png_calculate_crc,(png_structrp png_ptr,
   png_const_bytep ptr, size_t length),PNG_EMPTY);

#ifdef PNG_WRITE_FLUSH_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_flush,(png_structrp png_ptr),PNG_EMPTY);
#endif

/* Write various chunks */

/* Write the IHDR chunk, and update the png_struct with the necessary
 * information.
 */
PNG_INTERNAL_FUNCTION(void,png_write_IHDR,(png_structrp png_ptr,
   png_uint_32 width, png_uint_32 height, int bit_depth, int color_type,
   int compression_method, int filter_method, int interlace_method),PNG_EMPTY);

PNG_INTERNAL_FUNCTION(void,png_write_PLTE,(png_structrp png_ptr,
   png_const_colorp palette, png_uint_32 num_pal),PNG_EMPTY);

PNG_INTERNAL_FUNCTION(void,png_compress_IDAT,(png_structrp png_ptr,
   png_const_bytep row_data, png_alloc_size_t row_data_length, int flush),
   PNG_EMPTY);

PNG_INTERNAL_FUNCTION(void,png_write_IEND,(png_structrp png_ptr),PNG_EMPTY);

#ifdef PNG_WRITE_gAMA_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_gAMA_fixed,(png_structrp png_ptr,
    png_fixed_point file_gamma),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_sBIT_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_sBIT,(png_structrp png_ptr,
    png_const_color_8p sbit, int color_type),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_cHRM_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_cHRM_fixed,(png_structrp png_ptr,
    const png_xy *xy), PNG_EMPTY);
   /* The xy value must have been previously validated */
#endif

#ifdef PNG_WRITE_sRGB_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr,
    int intent),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_eXIf_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_eXIf,(png_structrp png_ptr,
    png_bytep exif, int num_exif),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_iCCP_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
   png_const_charp name, png_const_bytep profile), PNG_EMPTY);
   /* The profile must have been previously validated for correctness, the
    * length comes from the first four bytes.  Only the base, deflate,
    * compression is supported.
    */
#endif

#ifdef PNG_WRITE_sPLT_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_sPLT,(png_structrp png_ptr,
    png_const_sPLT_tp palette),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_tRNS_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_tRNS,(png_structrp png_ptr,
    png_const_bytep trans, png_const_color_16p values, int number,
    int color_type),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_bKGD_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_bKGD,(png_structrp png_ptr,
    png_const_color_16p values, int color_type),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_hIST_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_hIST,(png_structrp png_ptr,
    png_const_uint_16p hist, int num_hist),PNG_EMPTY);
#endif

/* Chunks that have keywords */
#ifdef PNG_WRITE_tEXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_tEXt,(png_structrp png_ptr,
   png_const_charp key, png_const_charp text, size_t text_len),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_zTXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_zTXt,(png_structrp png_ptr, png_const_charp
    key, png_const_charp text, int compression),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_iTXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_iTXt,(png_structrp png_ptr,
    int compression, png_const_charp key, png_const_charp lang,
    png_const_charp lang_key, png_const_charp text),PNG_EMPTY);
#endif

#ifdef PNG_TEXT_SUPPORTED  /* Added at version 1.0.14 and 1.2.4 */
PNG_INTERNAL_FUNCTION(int,png_set_text_2,(png_const_structrp png_ptr,
    png_inforp info_ptr, png_const_textp text_ptr, int num_text),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_oFFs_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_oFFs,(png_structrp png_ptr,
    png_int_32 x_offset, png_int_32 y_offset, int unit_type),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_pCAL_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_pCAL,(png_structrp png_ptr,
    png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams,
    png_const_charp units, png_charpp params),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_pHYs_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_pHYs,(png_structrp png_ptr,
    png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
    int unit_type),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_tIME_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_tIME,(png_structrp png_ptr,
    png_const_timep mod_time),PNG_EMPTY);
#endif

#ifdef PNG_WRITE_sCAL_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_sCAL_s,(png_structrp png_ptr,
    int unit, png_const_charp width, png_const_charp height),PNG_EMPTY);
#endif

/* Called when finished processing a row of data */
PNG_INTERNAL_FUNCTION(void,png_write_finish_row,(png_structrp png_ptr),
    PNG_EMPTY);

/* Internal use only.   Called before first row of data */
PNG_INTERNAL_FUNCTION(void,png_write_start_row,(png_structrp png_ptr),
    PNG_EMPTY);

/* Combine a row of data, dealing with alpha, etc. if requested.  'row' is an
 * array of png_ptr->width pixels.  If the image is not interlaced or this
 * is the final pass this just does a memcpy, otherwise the "display" flag
 * is used to determine whether to copy pixels that are not in the current pass.
 *
 * Because 'png_do_read_interlace' (below) replicates pixels this allows this
 * function to achieve the documented 'blocky' appearance during interlaced read
 * if display is 1 and the 'sparkle' appearance, where existing pixels in 'row'
 * are not changed if they are not in the current pass, when display is 0.
 *
 * 'display' must be 0 or 1, otherwise the memcpy will be done regardless.
 *
 * The API always reads from the png_struct row buffer and always assumes that
 * it is full width (png_do_read_interlace has already been called.)
 *
 * This function is only ever used to write to row buffers provided by the
 * caller of the relevant libpng API and the row must have already been
 * transformed by the read transformations.
 *
 * The PNG_USE_COMPILE_TIME_MASKS option causes generation of pre-computed
 * bitmasks for use within the code, otherwise runtime generated masks are used.
 * The default is compile time masks.
 */
#ifndef PNG_USE_COMPILE_TIME_MASKS
#  define PNG_USE_COMPILE_TIME_MASKS 1
#endif
PNG_INTERNAL_FUNCTION(void,png_combine_row,(png_const_structrp png_ptr,
    png_bytep row, int display),PNG_EMPTY);

#ifdef PNG_READ_INTERLACING_SUPPORTED
/* Expand an interlaced row: the 'row_info' describes the pass data that has
 * been read in and must correspond to the pixels in 'row', the pixels are
 * expanded (moved apart) in 'row' to match the final layout, when doing this
 * the pixels are *replicated* to the intervening space.  This is essential for
 * the correct operation of png_combine_row, above.
 */
PNG_INTERNAL_FUNCTION(void,png_do_read_interlace,(png_row_infop row_info,
    png_bytep row, int pass, png_uint_32 transformations),PNG_EMPTY);
#endif

/* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */

#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Grab pixels out of a row for an interlaced pass */
PNG_INTERNAL_FUNCTION(void,png_do_write_interlace,(png_row_infop row_info,
    png_bytep row, int pass),PNG_EMPTY);
#endif

/* Unfilter a row: check the filter value before calling this, there is no point
 * calling it for PNG_FILTER_VALUE_NONE.
 */
PNG_INTERNAL_FUNCTION(void,png_read_filter_row,(png_structrp pp, png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row, int filter),PNG_EMPTY);

#if PNG_ARM_NEON_OPT > 0
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_neon,(png_row_infop row_info,
    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
#endif

#if PNG_MIPS_MSA_OPT > 0
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_msa,(png_row_infop row_info,
    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
#endif

#if PNG_POWERPC_VSX_OPT > 0
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_vsx,(png_row_infop row_info,
    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
#endif

#if PNG_INTEL_SSE_IMPLEMENTATION > 0
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
#endif

/* Choose the best filter to use and filter the row data */
PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
    png_row_infop row_info),PNG_EMPTY);

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
   png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
   /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
    * is NULL the function checks, instead, for the end of the stream.  In this
    * case a benign error will be issued if the stream end is not found or if
    * extra data has to be consumed.
    */
PNG_INTERNAL_FUNCTION(void,png_read_finish_IDAT,(png_structrp png_ptr),
   PNG_EMPTY);
   /* This cleans up when the IDAT LZ stream does not end when the last image
    * byte is read; there is still some pending input.
    */

PNG_INTERNAL_FUNCTION(void,png_read_finish_row,(png_structrp png_ptr),
   PNG_EMPTY);
   /* Finish a row while reading, dealing with interlacing passes, etc. */
#endif /* SEQUENTIAL_READ */

/* Initialize the row buffers, etc. */
PNG_INTERNAL_FUNCTION(void,png_read_start_row,(png_structrp png_ptr),PNG_EMPTY);

#if ZLIB_VERNUM >= 0x1240
PNG_INTERNAL_FUNCTION(int,png_zlib_inflate,(png_structrp png_ptr, int flush),
      PNG_EMPTY);
#  define PNG_INFLATE(pp, flush) png_zlib_inflate(pp, flush)
#else /* Zlib < 1.2.4 */
#  define PNG_INFLATE(pp, flush) inflate(&(pp)->zstream, flush)
#endif /* Zlib < 1.2.4 */

#ifdef PNG_READ_TRANSFORMS_SUPPORTED
/* Optional call to update the users info structure */
PNG_INTERNAL_FUNCTION(void,png_read_transform_info,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
#endif

/* Shared transform functions, defined in pngtran.c */
#if defined(PNG_WRITE_FILLER_SUPPORTED) || \
    defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
PNG_INTERNAL_FUNCTION(void,png_do_strip_channel,(png_row_infop row_info,
    png_bytep row, int at_start),PNG_EMPTY);
#endif

#ifdef PNG_16BIT_SUPPORTED
#if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
PNG_INTERNAL_FUNCTION(void,png_do_swap,(png_row_infop row_info,
    png_bytep row),PNG_EMPTY);
#endif
#endif

#if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
    defined(PNG_WRITE_PACKSWAP_SUPPORTED)
PNG_INTERNAL_FUNCTION(void,png_do_packswap,(png_row_infop row_info,
    png_bytep row),PNG_EMPTY);
#endif

#if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
PNG_INTERNAL_FUNCTION(void,png_do_invert,(png_row_infop row_info,
    png_bytep row),PNG_EMPTY);
#endif

#if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
PNG_INTERNAL_FUNCTION(void,png_do_bgr,(png_row_infop row_info,
    png_bytep row),PNG_EMPTY);
#endif

/* The following decodes the appropriate chunks, and does error correction,
 * then calls the appropriate callback for the chunk if it is valid.
 */

/* Decode the IHDR chunk */
PNG_INTERNAL_FUNCTION(void,png_handle_IHDR,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_handle_PLTE,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_handle_IEND,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);

#ifdef PNG_READ_bKGD_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_bKGD,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_cHRM_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_cHRM,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_eXIf_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_eXIf,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_gAMA_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_gAMA,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_hIST_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_hIST,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_iCCP_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_iCCP,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif /* READ_iCCP */

#ifdef PNG_READ_iTXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_iTXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_oFFs_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_oFFs,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_pCAL_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_pCAL,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_pHYs_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_pHYs,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_sBIT_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_sBIT,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_sCAL_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_sCAL,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_sPLT_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_sPLT,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif /* READ_sPLT */

#ifdef PNG_READ_sRGB_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_sRGB,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_tEXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_tEXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_tIME_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_tIME,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_tRNS_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_tRNS,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

#ifdef PNG_READ_zTXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_zTXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif

PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_const_structrp png_ptr,
    const png_uint_32 chunk_name),PNG_EMPTY);

PNG_INTERNAL_FUNCTION(void,png_check_chunk_length,(png_const_structrp png_ptr,
    const png_uint_32 chunk_length),PNG_EMPTY);

PNG_INTERNAL_FUNCTION(void,png_handle_unknown,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length, int keep),PNG_EMPTY);
   /* This is the function that gets called for unknown chunks.  The 'keep'
    * argument is either non-zero for a known chunk that has been set to be
    * handled as unknown or zero for an unknown chunk.  By default the function
    * just skips the chunk or errors out if it is critical.
    */

#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
    defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
PNG_INTERNAL_FUNCTION(int,png_chunk_unknown_handling,
    (png_const_structrp png_ptr, png_uint_32 chunk_name),PNG_EMPTY);
   /* Exactly as the API png_handle_as_unknown() except that the argument is a
    * 32-bit chunk name, not a string.
    */
#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */

/* Handle the transformations for reading and writing */
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_do_read_transformations,(png_structrp png_ptr,
   png_row_infop row_info),PNG_EMPTY);
#endif
#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_do_write_transformations,(png_structrp png_ptr,
   png_row_infop row_info),PNG_EMPTY);
#endif

#ifdef PNG_READ_TRANSFORMS_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_init_read_transformations,(png_structrp png_ptr),
    PNG_EMPTY);
#endif

#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_push_read_chunk,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_read_sig,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_check_crc,(png_structrp png_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_save_buffer,(png_structrp png_ptr),
    PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_restore_buffer,(png_structrp png_ptr,
    png_bytep buffer, size_t buffer_length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_read_IDAT,(png_structrp png_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_process_IDAT_data,(png_structrp png_ptr,
    png_bytep buffer, size_t buffer_length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_process_row,(png_structrp png_ptr),
    PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_handle_unknown,(png_structrp png_ptr,
   png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_have_info,(png_structrp png_ptr,
   png_inforp info_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_have_end,(png_structrp png_ptr,
   png_inforp info_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_have_row,(png_structrp png_ptr,
    png_bytep row),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_read_end,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_process_some_data,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_push_finish_row,(png_structrp png_ptr),
    PNG_EMPTY);
#  ifdef PNG_READ_tEXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_push_handle_tEXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_read_tEXt,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
#  endif
#  ifdef PNG_READ_zTXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_push_handle_zTXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_read_zTXt,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
#  endif
#  ifdef PNG_READ_iTXt_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_push_handle_iTXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_push_read_iTXt,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
#  endif

#endif /* PROGRESSIVE_READ */

#ifdef PNG_APNG_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_ensure_fcTL_is_valid,(png_structp png_ptr,
   png_uint_32 width, png_uint_32 height,
   png_uint_32 x_offset, png_uint_32 y_offset,
   png_uint_16 delay_num, png_uint_16 delay_den,
   png_byte dispose_op, png_byte blend_op),PNG_EMPTY);

#ifdef PNG_READ_APNG_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_acTL,(png_structp png_ptr,
   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_handle_fcTL,(png_structp png_ptr,
   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_handle_fdAT,(png_structp png_ptr,
   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_have_info,(png_structp png_ptr,
   png_infop info_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_ensure_sequence_number,(png_structp png_ptr,
   png_uint_32 length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_reset,(png_structp png_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_read_reinit,(png_structp png_ptr,
   png_infop info_ptr),PNG_EMPTY);
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_progressive_read_reset,(png_structp png_ptr),
   PNG_EMPTY);
#endif /* PROGRESSIVE_READ */
#endif /* READ_APNG */

#ifdef PNG_WRITE_APNG_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_acTL,(png_structp png_ptr,
   png_uint_32 num_frames, png_uint_32 num_plays),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_fcTL,(png_structp png_ptr,
   png_uint_32 width, png_uint_32 height,
   png_uint_32 x_offset, png_uint_32 y_offset,
   png_uint_16 delay_num, png_uint_16 delay_den,
   png_byte dispose_op, png_byte blend_op),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_fdAT,(png_structp png_ptr,
   png_const_bytep data, png_size_t length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_reset,(png_structp png_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_reinit,(png_structp png_ptr,
   png_infop info_ptr, png_uint_32 width, png_uint_32 height),PNG_EMPTY);
#endif /* WRITE_APNG */
#endif /* APNG */

/* Added at libpng version 1.6.0 */
#ifdef PNG_GAMMA_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_colorspace_set_gamma,(png_const_structrp png_ptr,
    png_colorspacerp colorspace, png_fixed_point gAMA), PNG_EMPTY);
   /* Set the colorspace gamma with a value provided by the application or by
    * the gAMA chunk on read.  The value will override anything set by an ICC
    * profile.
    */

PNG_INTERNAL_FUNCTION(void,png_colorspace_sync_info,(png_const_structrp png_ptr,
    png_inforp info_ptr), PNG_EMPTY);
   /* Synchronize the info 'valid' flags with the colorspace */

PNG_INTERNAL_FUNCTION(void,png_colorspace_sync,(png_const_structrp png_ptr,
    png_inforp info_ptr), PNG_EMPTY);
   /* Copy the png_struct colorspace to the info_struct and call the above to
    * synchronize the flags.  Checks for NULL info_ptr and does nothing.
    */
#endif

/* Added at libpng version 1.4.0 */
#ifdef PNG_COLORSPACE_SUPPORTED
/* These internal functions are for maintaining the colorspace structure within
 * a png_info or png_struct (or, indeed, both).
 */
PNG_INTERNAL_FUNCTION(int,png_colorspace_set_chromaticities,
   (png_const_structrp png_ptr, png_colorspacerp colorspace, const png_xy *xy,
    int preferred), PNG_EMPTY);

PNG_INTERNAL_FUNCTION(int,png_colorspace_set_endpoints,
   (png_const_structrp png_ptr, png_colorspacerp colorspace, const png_XYZ *XYZ,
    int preferred), PNG_EMPTY);

#ifdef PNG_sRGB_SUPPORTED
PNG_INTERNAL_FUNCTION(int,png_colorspace_set_sRGB,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, int intent), PNG_EMPTY);
   /* This does set the colorspace gAMA and cHRM values too, but doesn't set the
    * flags to write them, if it returns false there was a problem and an error
    * message has already been output (but the colorspace may still need to be
    * synced to record the invalid flag).
    */
#endif /* sRGB */

#ifdef PNG_iCCP_SUPPORTED
PNG_INTERNAL_FUNCTION(int,png_colorspace_set_ICC,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length, png_const_bytep profile, int color_type),
   PNG_EMPTY);
   /* The 'name' is used for information only */

/* Routines for checking parts of an ICC profile. */
#ifdef PNG_READ_iCCP_SUPPORTED
PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length), PNG_EMPTY);
#endif /* READ_iCCP */
PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length,
   png_const_bytep profile /* first 132 bytes only */, int color_type),
   PNG_EMPTY);
PNG_INTERNAL_FUNCTION(int,png_icc_check_tag_table,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length,
   png_const_bytep profile /* header plus whole tag table */), PNG_EMPTY);
#ifdef PNG_sRGB_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_icc_set_sRGB,(
   png_const_structrp png_ptr, png_colorspacerp colorspace,
   png_const_bytep profile, uLong adler), PNG_EMPTY);
   /* 'adler' is the Adler32 checksum of the uncompressed profile data. It may
    * be zero to indicate that it is not available.  It is used, if provided,
    * as a fast check on the profile when checking to see if it is sRGB.
    */
#endif
#endif /* iCCP */

#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_colorspace_set_rgb_coefficients,
   (png_structrp png_ptr), PNG_EMPTY);
   /* Set the rgb_to_gray coefficients from the colorspace Y values */
#endif /* READ_RGB_TO_GRAY */
#endif /* COLORSPACE */

/* Added at libpng version 1.4.0 */
PNG_INTERNAL_FUNCTION(void,png_check_IHDR,(png_const_structrp png_ptr,
    png_uint_32 width, png_uint_32 height, int bit_depth,
    int color_type, int interlace_type, int compression_type,
    int filter_type),PNG_EMPTY);

/* Added at libpng version 1.5.10 */
#if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
    defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
PNG_INTERNAL_FUNCTION(void,png_do_check_palette_indexes,
   (png_structrp png_ptr, png_row_infop row_info),PNG_EMPTY);
#endif

#if defined(PNG_FLOATING_POINT_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
PNG_INTERNAL_FUNCTION(void,png_fixed_error,(png_const_structrp png_ptr,
   png_const_charp name),PNG_NORETURN);
#endif

/* Puts 'string' into 'buffer' at buffer[pos], taking care never to overwrite
 * the end.  Always leaves the buffer nul terminated.  Never errors out (and
 * there is no error code.)
 */
PNG_INTERNAL_FUNCTION(size_t,png_safecat,(png_charp buffer, size_t bufsize,
   size_t pos, png_const_charp string),PNG_EMPTY);

/* Various internal functions to handle formatted warning messages, currently
 * only implemented for warnings.
 */
#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
/* Utility to dump an unsigned value into a buffer, given a start pointer and
 * and end pointer (which should point just *beyond* the end of the buffer!)
 * Returns the pointer to the start of the formatted string.  This utility only
 * does unsigned values.
 */
PNG_INTERNAL_FUNCTION(png_charp,png_format_number,(png_const_charp start,
   png_charp end, int format, png_alloc_size_t number),PNG_EMPTY);

/* Convenience macro that takes an array: */
#define PNG_FORMAT_NUMBER(buffer,format,number) \
   png_format_number(buffer, buffer + (sizeof buffer), format, number)

/* Suggested size for a number buffer (enough for 64 bits and a sign!) */
#define PNG_NUMBER_BUFFER_SIZE 24

/* These are the integer formats currently supported, the name is formed from
 * the standard printf(3) format string.
 */
#define PNG_NUMBER_FORMAT_u     1 /* chose unsigned API! */
#define PNG_NUMBER_FORMAT_02u   2
#define PNG_NUMBER_FORMAT_d     1 /* chose signed API! */
#define PNG_NUMBER_FORMAT_02d   2
#define PNG_NUMBER_FORMAT_x     3
#define PNG_NUMBER_FORMAT_02x   4
#define PNG_NUMBER_FORMAT_fixed 5 /* choose the signed API */
#endif

#ifdef PNG_WARNINGS_SUPPORTED
/* New defines and members adding in libpng-1.5.4 */
#  define PNG_WARNING_PARAMETER_SIZE 32
#  define PNG_WARNING_PARAMETER_COUNT 8 /* Maximum 9; see pngerror.c */

/* An l-value of this type has to be passed to the APIs below to cache the
 * values of the parameters to a formatted warning message.
 */
typedef char png_warning_parameters[PNG_WARNING_PARAMETER_COUNT][
   PNG_WARNING_PARAMETER_SIZE];

PNG_INTERNAL_FUNCTION(void,png_warning_parameter,(png_warning_parameters p,
   int number, png_const_charp string),PNG_EMPTY);
   /* Parameters are limited in size to PNG_WARNING_PARAMETER_SIZE characters,
    * including the trailing '\0'.
    */
PNG_INTERNAL_FUNCTION(void,png_warning_parameter_unsigned,
   (png_warning_parameters p, int number, int format, png_alloc_size_t value),
   PNG_EMPTY);
   /* Use png_alloc_size_t because it is an unsigned type as big as any we
    * need to output.  Use the following for a signed value.
    */
PNG_INTERNAL_FUNCTION(void,png_warning_parameter_signed,
   (png_warning_parameters p, int number, int format, png_int_32 value),
   PNG_EMPTY);

PNG_INTERNAL_FUNCTION(void,png_formatted_warning,(png_const_structrp png_ptr,
   png_warning_parameters p, png_const_charp message),PNG_EMPTY);
   /* 'message' follows the X/Open approach of using @1, @2 to insert
    * parameters previously supplied using the above functions.  Errors in
    * specifying the parameters will simply result in garbage substitutions.
    */
#endif

#ifdef PNG_BENIGN_ERRORS_SUPPORTED
/* Application errors (new in 1.6); use these functions (declared below) for
 * errors in the parameters or order of API function calls on read.  The
 * 'warning' should be used for an error that can be handled completely; the
 * 'error' for one which can be handled safely but which may lose application
 * information or settings.
 *
 * By default these both result in a png_error call prior to release, while in a
 * released version the 'warning' is just a warning.  However if the application
 * explicitly disables benign errors (explicitly permitting the code to lose
 * information) they both turn into warnings.
 *
 * If benign errors aren't supported they end up as the corresponding base call
 * (png_warning or png_error.)
 */
PNG_INTERNAL_FUNCTION(void,png_app_warning,(png_const_structrp png_ptr,
   png_const_charp message),PNG_EMPTY);
   /* The application provided invalid parameters to an API function or called
    * an API function at the wrong time, libpng can completely recover.
    */

PNG_INTERNAL_FUNCTION(void,png_app_error,(png_const_structrp png_ptr,
   png_const_charp message),PNG_EMPTY);
   /* As above but libpng will ignore the call, or attempt some other partial
    * recovery from the error.
    */
#else
#  define png_app_warning(pp,s) png_warning(pp,s)
#  define png_app_error(pp,s) png_error(pp,s)
#endif

PNG_INTERNAL_FUNCTION(void,png_chunk_report,(png_const_structrp png_ptr,
   png_const_charp message, int error),PNG_EMPTY);
   /* Report a recoverable issue in chunk data.  On read this is used to report
    * a problem found while reading a particular chunk and the
    * png_chunk_benign_error or png_chunk_warning function is used as
    * appropriate.  On write this is used to report an error that comes from
    * data set via an application call to a png_set_ API and png_app_error or
    * png_app_warning is used as appropriate.
    *
    * The 'error' parameter must have one of the following values:
    */
#define PNG_CHUNK_WARNING     0 /* never an error */
#define PNG_CHUNK_WRITE_ERROR 1 /* an error only on write */
#define PNG_CHUNK_ERROR       2 /* always an error */

/* ASCII to FP interfaces, currently only implemented if sCAL
 * support is required.
 */
#if defined(PNG_sCAL_SUPPORTED)
/* MAX_DIGITS is actually the maximum number of characters in an sCAL
 * width or height, derived from the precision (number of significant
 * digits - a build time settable option) and assumptions about the
 * maximum ridiculous exponent.
 */
#define PNG_sCAL_MAX_DIGITS (PNG_sCAL_PRECISION+1/*.*/+1/*E*/+10/*exponent*/)

#ifdef PNG_FLOATING_POINT_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_ascii_from_fp,(png_const_structrp png_ptr,
   png_charp ascii, size_t size, double fp, unsigned int precision),
   PNG_EMPTY);
#endif /* FLOATING_POINT */

#ifdef PNG_FIXED_POINT_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_ascii_from_fixed,(png_const_structrp png_ptr,
   png_charp ascii, size_t size, png_fixed_point fp),PNG_EMPTY);
#endif /* FIXED_POINT */
#endif /* sCAL */

#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
/* An internal API to validate the format of a floating point number.
 * The result is the index of the next character.  If the number is
 * not valid it will be the index of a character in the supposed number.
 *
 * The format of a number is defined in the PNG extensions specification
 * and this API is strictly conformant to that spec, not anyone elses!
 *
 * The format as a regular expression is:
 *
 * [+-]?[0-9]+.?([Ee][+-]?[0-9]+)?
 *
 * or:
 *
 * [+-]?.[0-9]+(.[0-9]+)?([Ee][+-]?[0-9]+)?
 *
 * The complexity is that either integer or fraction must be present and the
 * fraction is permitted to have no digits only if the integer is present.
 *
 * NOTE: The dangling E problem.
 *   There is a PNG valid floating point number in the following:
 *
 *       PNG floating point numbers are not greedy.
 *
 *   Working this out requires *TWO* character lookahead (because of the
 *   sign), the parser does not do this - it will fail at the 'r' - this
 *   doesn't matter for PNG sCAL chunk values, but it requires more care
 *   if the value were ever to be embedded in something more complex.  Use
 *   ANSI-C strtod if you need the lookahead.
 */
/* State table for the parser. */
#define PNG_FP_INTEGER    0  /* before or in integer */
#define PNG_FP_FRACTION   1  /* before or in fraction */
#define PNG_FP_EXPONENT   2  /* before or in exponent */
#define PNG_FP_STATE      3  /* mask for the above */
#define PNG_FP_SAW_SIGN   4  /* Saw +/- in current state */
#define PNG_FP_SAW_DIGIT  8  /* Saw a digit in current state */
#define PNG_FP_SAW_DOT   16  /* Saw a dot in current state */
#define PNG_FP_SAW_E     32  /* Saw an E (or e) in current state */
#define PNG_FP_SAW_ANY   60  /* Saw any of the above 4 */

/* These three values don't affect the parser.  They are set but not used.
 */
#define PNG_FP_WAS_VALID 64  /* Preceding substring is a valid fp number */
#define PNG_FP_NEGATIVE 128  /* A negative number, including "-0" */
#define PNG_FP_NONZERO  256  /* A non-zero value */
#define PNG_FP_STICKY   448  /* The above three flags */

/* This is available for the caller to store in 'state' if required.  Do not
 * call the parser after setting it (the parser sometimes clears it.)
 */
#define PNG_FP_INVALID  512  /* Available for callers as a distinct value */

/* Result codes for the parser (boolean - true meants ok, false means
 * not ok yet.)
 */
#define PNG_FP_MAYBE      0  /* The number may be valid in the future */
#define PNG_FP_OK         1  /* The number is valid */

/* Tests on the sticky non-zero and negative flags.  To pass these checks
 * the state must also indicate that the whole number is valid - this is
 * achieved by testing PNG_FP_SAW_DIGIT (see the implementation for why this
 * is equivalent to PNG_FP_OK above.)
 */
#define PNG_FP_NZ_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NEGATIVE | PNG_FP_NONZERO)
   /* NZ_MASK: the string is valid and a non-zero negative value */
#define PNG_FP_Z_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NONZERO)
   /* Z MASK: the string is valid and a non-zero value. */
   /* PNG_FP_SAW_DIGIT: the string is valid. */
#define PNG_FP_IS_ZERO(state) (((state) & PNG_FP_Z_MASK) == PNG_FP_SAW_DIGIT)
#define PNG_FP_IS_POSITIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_Z_MASK)
#define PNG_FP_IS_NEGATIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_NZ_MASK)

/* The actual parser.  This can be called repeatedly. It updates
 * the index into the string and the state variable (which must
 * be initialized to 0).  It returns a result code, as above.  There
 * is no point calling the parser any more if it fails to advance to
 * the end of the string - it is stuck on an invalid character (or
 * terminated by '\0').
 *
 * Note that the pointer will consume an E or even an E+ and then leave
 * a 'maybe' state even though a preceding integer.fraction is valid.
 * The PNG_FP_WAS_VALID flag indicates that a preceding substring was
 * a valid number.  It's possible to recover from this by calling
 * the parser again (from the start, with state 0) but with a string
 * that omits the last character (i.e. set the size to the index of
 * the problem character.)  This has not been tested within libpng.
 */
PNG_INTERNAL_FUNCTION(int,png_check_fp_number,(png_const_charp string,
   size_t size, int *statep, png_size_tp whereami),PNG_EMPTY);

/* This is the same but it checks a complete string and returns true
 * only if it just contains a floating point number.  As of 1.5.4 this
 * function also returns the state at the end of parsing the number if
 * it was valid (otherwise it returns 0.)  This can be used for testing
 * for negative or zero values using the sticky flag.
 */
PNG_INTERNAL_FUNCTION(int,png_check_fp_string,(png_const_charp string,
   size_t size),PNG_EMPTY);
#endif /* pCAL || sCAL */

#if defined(PNG_GAMMA_SUPPORTED) ||\
    defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
/* Added at libpng version 1.5.0 */
/* This is a utility to provide a*times/div (rounded) and indicate
 * if there is an overflow.  The result is a boolean - false (0)
 * for overflow, true (1) if no overflow, in which case *res
 * holds the result.
 */
PNG_INTERNAL_FUNCTION(int,png_muldiv,(png_fixed_point_p res, png_fixed_point a,
   png_int_32 multiplied_by, png_int_32 divided_by),PNG_EMPTY);
#endif

#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
/* Same deal, but issue a warning on overflow and return 0. */
PNG_INTERNAL_FUNCTION(png_fixed_point,png_muldiv_warn,
   (png_const_structrp png_ptr, png_fixed_point a, png_int_32 multiplied_by,
   png_int_32 divided_by),PNG_EMPTY);
#endif

#ifdef PNG_GAMMA_SUPPORTED
/* Calculate a reciprocal - used for gamma values.  This returns
 * 0 if the argument is 0 in order to maintain an undefined value;
 * there are no warnings.
 */
PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal,(png_fixed_point a),
   PNG_EMPTY);

#ifdef PNG_READ_GAMMA_SUPPORTED
/* The same but gives a reciprocal of the product of two fixed point
 * values.  Accuracy is suitable for gamma calculations but this is
 * not exact - use png_muldiv for that.  Only required at present on read.
 */
PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal2,(png_fixed_point a,
   png_fixed_point b),PNG_EMPTY);
#endif

/* Return true if the gamma value is significantly different from 1.0 */
PNG_INTERNAL_FUNCTION(int,png_gamma_significant,(png_fixed_point gamma_value),
   PNG_EMPTY);
#endif

#ifdef PNG_READ_GAMMA_SUPPORTED
/* Internal fixed point gamma correction.  These APIs are called as
 * required to convert single values - they don't need to be fast,
 * they are not used when processing image pixel values.
 *
 * While the input is an 'unsigned' value it must actually be the
 * correct bit value - 0..255 or 0..65535 as required.
 */
PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_correct,(png_structrp png_ptr,
   unsigned int value, png_fixed_point gamma_value),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_16bit_correct,(unsigned int value,
   png_fixed_point gamma_value),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(png_byte,png_gamma_8bit_correct,(unsigned int value,
   png_fixed_point gamma_value),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_destroy_gamma_table,(png_structrp png_ptr),
   PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_build_gamma_table,(png_structrp png_ptr,
   int bit_depth),PNG_EMPTY);
#endif

/* SIMPLIFIED READ/WRITE SUPPORT */
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
/* The internal structure that png_image::opaque points to. */
typedef struct png_control
{
   png_structp png_ptr;
   png_infop   info_ptr;
   png_voidp   error_buf;           /* Always a jmp_buf at present. */

   png_const_bytep memory;          /* Memory buffer. */
   size_t          size;            /* Size of the memory buffer. */

   unsigned int for_write       :1; /* Otherwise it is a read structure */
   unsigned int owned_file      :1; /* We own the file in io_ptr */
} png_control;

/* Return the pointer to the jmp_buf from a png_control: necessary because C
 * does not reveal the type of the elements of jmp_buf.
 */
#ifdef __cplusplus
#  define png_control_jmp_buf(pc) (((jmp_buf*)((pc)->error_buf))[0])
#else
#  define png_control_jmp_buf(pc) ((pc)->error_buf)
#endif

/* Utility to safely execute a piece of libpng code catching and logging any
 * errors that might occur.  Returns true on success, false on failure (either
 * of the function or as a result of a png_error.)
 */
PNG_INTERNAL_CALLBACK(void,png_safe_error,(png_structp png_ptr,
   png_const_charp error_message),PNG_NORETURN);

#ifdef PNG_WARNINGS_SUPPORTED
PNG_INTERNAL_CALLBACK(void,png_safe_warning,(png_structp png_ptr,
   png_const_charp warning_message),PNG_EMPTY);
#else
#  define png_safe_warning 0/*dummy argument*/
#endif

PNG_INTERNAL_FUNCTION(int,png_safe_execute,(png_imagep image,
   int (*function)(png_voidp), png_voidp arg),PNG_EMPTY);

/* Utility to log an error; this also cleans up the png_image; the function
 * always returns 0 (false).
 */
PNG_INTERNAL_FUNCTION(int,png_image_error,(png_imagep image,
   png_const_charp error_message),PNG_EMPTY);

#ifndef PNG_SIMPLIFIED_READ_SUPPORTED
/* png_image_free is used by the write code but not exported */
PNG_INTERNAL_FUNCTION(void, png_image_free, (png_imagep image), PNG_EMPTY);
#endif /* !SIMPLIFIED_READ */

#endif /* SIMPLIFIED READ/WRITE */

/* These are initialization functions for hardware specific PNG filter
 * optimizations; list these here then select the appropriate one at compile
 * time using the macro PNG_FILTER_OPTIMIZATIONS.  If the macro is not defined
 * the generic code is used.
 */
#ifdef PNG_FILTER_OPTIMIZATIONS
PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
   unsigned int bpp), PNG_EMPTY);
   /* Just declare the optimization that will be used */
#else
   /* List *all* the possible optimizations here - this branch is required if
    * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
    * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
    */
#  if PNG_ARM_NEON_OPT > 0
PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
#endif

#if PNG_MIPS_MSA_OPT > 0
PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_msa,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
#endif

#  if PNG_INTEL_SSE_IMPLEMENTATION > 0
PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
#  endif
#endif

PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
   png_const_charp key, png_bytep new_key), PNG_EMPTY);

/* Maintainer: Put new private prototypes here ^ */

#include "pngdebug.h"

#ifdef __cplusplus
}
#endif

#endif /* PNG_VERSION_INFO_ONLY */
#endif /* PNGPRIV_H */