    /* pngpriv.h - private declarations for use inside libpng
     *
     * For conditions of distribution and use, see copyright notice in png.h
     * Copyright (c) 1998-2013 Glenn Randers-Pehrson
     * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
     * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
     *
     * Last changed in libpng 1.6.7 [November 14, 2013]
     *
     * This code is released under the libpng license.
     * For conditions of distribution and use, see the disclaimer
     * and license in png.h
     */

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

    #ifndef PNGPRIV_H
    #define PNGPRIV_H

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

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

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

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

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

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

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

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

    /* Compile time options.
     * =====================
     * In a multi-arch build the compiler may compile the code several times for the
     * same object module, producing different binaries for different architectures.
     * When this happens configure-time setting of the target host options cannot be
     * done and this interferes with the handling of the ARM NEON optimizations, and
     * possibly other similar optimizations.  Put additional tests here; in general
     * this is needed when the same option can be changed at both compile time and
     * run time depending on the target OS (i.e. iOS vs Android.)
     *
     * NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
     * this is not possible with certain compilers (Oracle SUN OS CC), as a result
     * it is necessary to ensure that all extern functions that *might* be used
     * regardless of $(CFLAGS) get declared in this file.  The test on __ARM_NEON__
     * below is one example of this behavior because it is controlled by the
     * presence or not of -mfpu=neon on the GCC command line, it is possible to do
     * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
     * do this.
     */
    #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:
        */
    #  ifdef __ARM_NEON__
    #     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 control 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
    #     ifdef __ARM_NEON__
    #        if defined(__clang__)
                /* At present it is unknown by the libpng developers which versions
                 * of clang support the intrinsics, however some or perhaps all
                 * versions do not work with the assembler so this may be
                 * irrelevant, so just use the default (do nothing here.)
                 */
    #        elif defined(__GNUC__)
                /* GCC 4.5.4 NEON support is known to be broken.  4.6.3 is known to
                 * work, so if this *is* GCC, or G++, look for a version >4.5
                 */
    #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
    #              define PNG_ARM_NEON_IMPLEMENTATION 2
    #           endif /* no GNUC support */
    #        endif /* __GNUC__ */
    #     else /* !defined __ARM_NEON__ */
             /* The 'intrinsics' code simply won't compile without this -mfpu=neon:
              */
    #        define PNG_ARM_NEON_IMPLEMENTATION 2
    #     endif /* __ARM_NEON__ */
    #  endif /* !defined PNG_ARM_NEON_IMPLEMENTATION */

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

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

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

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

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

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

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

    #include "png.h"

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

    /* SECURITY and SAFETY:
     *
     * By default libpng is built without any internal limits on image size,
     * individual heap (png_malloc) allocations or the total amount of memory used.
     * If PNG_SAFE_LIMITS_SUPPORTED is defined, however, the limits below are used
     * (unless individually overridden).  These limits are believed to be fairly
     * safe, but builders of secure systems should verify the values against the
     * real system capabilities.
     */
    #ifdef PNG_SAFE_LIMITS_SUPPORTED
       /* 'safe' limits */
    #  ifndef PNG_USER_WIDTH_MAX
    #     define PNG_USER_WIDTH_MAX 1000000
    #  endif
    #  ifndef PNG_USER_HEIGHT_MAX
    #     define PNG_USER_HEIGHT_MAX 1000000
    #  endif
    #  ifndef PNG_USER_CHUNK_CACHE_MAX
    #     define PNG_USER_CHUNK_CACHE_MAX 128
    #  endif
    #  ifndef PNG_USER_CHUNK_MALLOC_MAX
    #     define PNG_USER_CHUNK_MALLOC_MAX 8000000
    #  endif
    #else
       /* values for no limits */
    #  ifndef PNG_USER_WIDTH_MAX
    #     define PNG_USER_WIDTH_MAX 0x7fffffff
    #  endif
    #  ifndef PNG_USER_HEIGHT_MAX
    #     define PNG_USER_HEIGHT_MAX 0x7fffffff
    #  endif
    #  ifndef PNG_USER_CHUNK_CACHE_MAX
    #     define PNG_USER_CHUNK_CACHE_MAX 0
    #  endif
    #  ifndef PNG_USER_CHUNK_MALLOC_MAX
    #     define PNG_USER_CHUNK_MALLOC_MAX 0
    #  endif
    #endif

    /* Moved to pngpriv.h at libpng-1.5.0 */
    /* NOTE: some of these may have been used in external applications as
     * these definitions were exposed in pngconf.h prior to 1.5.
     */

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

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

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

    /* If warnings or errors are turned off the code is disabled or redirected here.
     * From 1.5.4 functions have been added to allow very limited formatting of
     * error and warning messages - this code will also be disabled here.
     */
    #ifdef PNG_WARNINGS_SUPPORTED
    #  define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
    #else
    #  define png_warning(s1,s2) ((void)(s1))
    #  define png_chunk_warning(s1,s2) ((void)(s1))
    #  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_error(s1,s2) png_err(s1)
    #  define png_chunk_error(s1,s2) png_err(s1)
    #  define png_fixed_error(s1,s2) png_err(s1)
    #endif

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

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

    #ifndef PNG_VERSION_INFO_ONLY
    /* Other defines specific to compilers can go here.  Try to keep
     * them inside an appropriate ifdef/endif pair for portability.
     */
    #if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
        defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
       /* png.c requires the following ANSI-C constants if the conversion of
        * floating point to ASCII is implemented therein:
        *
        *  DBL_DIG  Maximum number of decimal digits (can be set to any constant)
        *  DBL_MIN  Smallest normalized fp number (can be set to an arbitrary value)
        *  DBL_MAX  Maximum floating point number (can be set to an arbitrary value)
        */
    #  include <float.h>

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

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

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

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

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

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

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

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

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

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

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

    /* Various modes of operation.  Note that after an init, mode is set to
     * zero automatically when the structure is created.  Three of these
     * are defined in png.h because they need to be visible to applications
     * that call png_set_unknown_chunk().
     */
    /* #define PNG_HAVE_IHDR            0x01 (defined in png.h) */
    /* #define PNG_HAVE_PLTE            0x02 (defined in png.h) */
    #define PNG_HAVE_IDAT               0x04
    /* #define PNG_AFTER_IDAT           0x08 (defined in png.h) */
    #define PNG_HAVE_IEND               0x10
                       /*               0x20 (unused) */
                       /*               0x40 (unused) */
                       /*               0x80 (unused) */
    #define PNG_HAVE_CHUNK_HEADER      0x100
    #define PNG_WROTE_tIME             0x200
    #define PNG_WROTE_INFO_BEFORE_PLTE 0x400
    #define PNG_BACKGROUND_IS_GRAY     0x800
    #define PNG_HAVE_PNG_SIGNATURE    0x1000
    #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
                       /*             0x4000 (unused) */
    #define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */

    /* Flags for the transformations the PNG library does on the image data */
    #define PNG_BGR                 0x0001
    #define PNG_INTERLACE           0x0002
    #define PNG_PACK                0x0004
    #define PNG_SHIFT               0x0008
    #define PNG_SWAP_BYTES          0x0010
    #define PNG_INVERT_MONO         0x0020
    #define PNG_QUANTIZE            0x0040
    #define PNG_COMPOSE             0x0080     /* Was PNG_BACKGROUND */
    #define PNG_BACKGROUND_EXPAND   0x0100
    #define PNG_EXPAND_16           0x0200     /* Added to libpng 1.5.2 */
    #define PNG_16_TO_8             0x0400     /* Becomes 'chop' in 1.5.4 */
    #define PNG_RGBA                0x0800
    #define PNG_EXPAND              0x1000
    #define PNG_GAMMA               0x2000
    #define PNG_GRAY_TO_RGB         0x4000
    #define PNG_FILLER              0x8000
    #define PNG_PACKSWAP           0x10000
    #define PNG_SWAP_ALPHA         0x20000
    #define PNG_STRIP_ALPHA        0x40000
    #define PNG_INVERT_ALPHA       0x80000
    #define PNG_USER_TRANSFORM    0x100000
    #define PNG_RGB_TO_GRAY_ERR   0x200000
    #define PNG_RGB_TO_GRAY_WARN  0x400000
    #define PNG_RGB_TO_GRAY       0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
    #define PNG_ENCODE_ALPHA      0x800000 /* Added to libpng-1.5.4 */
    #define PNG_ADD_ALPHA         0x1000000 /* Added to libpng-1.2.7 */
    #define PNG_EXPAND_tRNS       0x2000000 /* Added to libpng-1.2.9 */
    #define PNG_SCALE_16_TO_8     0x4000000 /* Added to libpng-1.5.4 */
                           /*   0x8000000 unused */
                           /*  0x10000000 unused */
                           /*  0x20000000 unused */
                           /*  0x40000000 unused */
    /* Flags for png_create_struct */
    #define PNG_STRUCT_PNG   0x0001
    #define PNG_STRUCT_INFO  0x0002

    /* Scaling factor for filter heuristic weighting calculations */
    #define PNG_WEIGHT_FACTOR (1<<(PNG_WEIGHT_SHIFT))
    #define PNG_COST_FACTOR (1<<(PNG_COST_SHIFT))

    /* Flags for the png_ptr->flags rather than declaring a byte for each one */
    #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
    #define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002 /* Added to libpng-1.6.0 */
                                      /*      0x0004    unused */
    #define PNG_FLAG_ZSTREAM_ENDED            0x0008 /* Added to libpng-1.6.0 */
                                      /*      0x0010    unused */
                                      /*      0x0020    unused */
    #define PNG_FLAG_ROW_INIT                 0x0040
    #define PNG_FLAG_FILLER_AFTER             0x0080
    #define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
    #define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
    #define PNG_FLAG_CRC_CRITICAL_USE         0x0400
    #define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
    #define PNG_FLAG_ASSUME_sRGB              0x1000 /* Added to libpng-1.5.4 */
    #define PNG_FLAG_OPTIMIZE_ALPHA           0x2000 /* Added to libpng-1.5.4 */
    #define PNG_FLAG_DETECT_UNINITIALIZED     0x4000 /* Added to libpng-1.5.4 */
    /* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000 */
    /* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000 */
    #define PNG_FLAG_LIBRARY_MISMATCH        0x20000
    #define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000
    #define PNG_FLAG_STRIP_ERROR_TEXT        0x80000
    #define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000 /* Added to libpng-1.4.0 */
    #define PNG_FLAG_APP_WARNINGS_WARN      0x200000 /* Added to libpng-1.6.0 */
    #define PNG_FLAG_APP_ERRORS_WARN        0x400000 /* Added to libpng-1.6.0 */
                                      /*    0x800000    unused */
                                      /*   0x1000000    unused */
                                      /*   0x2000000    unused */
                                      /*   0x4000000    unused */
                                      /*   0x8000000    unused */
                                      /*  0x10000000    unused */
                                      /*  0x20000000    unused */
                                      /*  0x40000000    unused */

    #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                         PNG_FLAG_CRC_ANCILLARY_NOWARN)

    #define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
                                         PNG_FLAG_CRC_CRITICAL_IGNORE)

    #define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
                                         PNG_FLAG_CRC_CRITICAL_MASK)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    /* 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, png_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_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, png_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, png_size_t text_len, 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);

    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);

    /* 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

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

    #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

    /* These are the functions that do the transformations */
    #ifdef PNG_READ_FILLER_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_read_filler,(png_row_infop row_info,
        png_bytep row, png_uint_32 filler, png_uint_32 flags),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_read_swap_alpha,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_write_swap_alpha,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_read_invert_alpha,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_write_invert_alpha,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #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

    #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
    PNG_INTERNAL_FUNCTION(int,png_do_rgb_to_gray,(png_structrp png_ptr,
        png_row_infop row_info, png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_gray_to_rgb,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_PACK_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_unpack,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_SHIFT_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_unshift,(png_row_infop row_info,
        png_bytep row, png_const_color_8p sig_bits),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

    #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_scale_16_to_8,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_chop,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_QUANTIZE_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_quantize,(png_row_infop row_info,
        png_bytep row, png_const_bytep palette_lookup,
        png_const_bytep quantize_lookup),PNG_EMPTY);

    #  ifdef PNG_CORRECT_PALETTE_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_correct_palette,(png_structrp png_ptr,
        png_colorp palette, int num_palette),PNG_EMPTY);
    #  endif
    #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

    #ifdef PNG_WRITE_PACK_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_pack,(png_row_infop row_info,
       png_bytep row, png_uint_32 bit_depth),PNG_EMPTY);
    #endif

    #ifdef PNG_WRITE_SHIFT_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_shift,(png_row_infop row_info,
        png_bytep row, png_const_color_8p bit_depth),PNG_EMPTY);
    #endif

    #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
        defined(PNG_READ_ALPHA_MODE_SUPPORTED)
    PNG_INTERNAL_FUNCTION(void,png_do_compose,(png_row_infop row_info,
        png_bytep row, png_structrp png_ptr),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_GAMMA_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_gamma,(png_row_infop row_info,
        png_bytep row, png_structrp png_ptr),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_encode_alpha,(png_row_infop row_info,
       png_bytep row, png_structrp png_ptr),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_EXPAND_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_expand_palette,(png_row_infop row_info,
        png_bytep row, png_const_colorp palette, png_const_bytep trans,
        int num_trans),PNG_EMPTY);
    PNG_INTERNAL_FUNCTION(void,png_do_expand,(png_row_infop row_info,
        png_bytep row, png_const_color_16p trans_color),PNG_EMPTY);
    #endif

    #ifdef PNG_READ_EXPAND_16_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_expand_16,(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_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 /* PNG_READ_iCCP_SUPPORTED */

    #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 /* PNG_READ_sPLT_SUPPORTED */

    #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_structrp png_ptr,
        png_uint_32 chunk_name),PNG_EMPTY);

    #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
    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 */
    #endif /* PNG_SET_UNKNOWN_CHUNKS_SUPPORTED */

    /* 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_crc_skip,(png_structrp png_ptr,
        png_uint_32 length),PNG_EMPTY);
    PNG_INTERNAL_FUNCTION(void,png_push_crc_finish,(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, png_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, png_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 /* PNG_PROGRESSIVE_READ_SUPPORTED */

    #ifdef PNG_MNG_FEATURES_SUPPORTED
    PNG_INTERNAL_FUNCTION(void,png_do_read_intrapixel,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    PNG_INTERNAL_FUNCTION(void,png_do_write_intrapixel,(png_row_infop row_info,
        png_bytep row),PNG_EMPTY);
    #endif

    /* 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. */
    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);
    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, png_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, png_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,
       png_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,
       png_size_t size),PNG_EMPTY);
    #endif /* pCAL || sCAL */

    #if defined(PNG_READ_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. */
       png_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_FUNCTION(void,png_safe_error,(png_structp png_ptr,
       png_const_charp error_message),PNG_NORETURN);

    #ifdef PNG_WARNINGS_SUPPORTED
    PNG_INTERNAL_FUNCTION(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.
        */
    PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
       (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
    #endif

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

    #include "pngdebug.h"

    #ifdef __cplusplus
    }
    #endif

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