/* pngpriv.h - private declarations for use inside libpng

 *

 * Copyright (c) 2018-2022 Cosmin Truta

 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson

 * Copyright (c) 1996-1997 Andreas Dilger

 * 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:

          */

#        if !defined(__aarch64__) && !defined(_M_ARM64)

            /* The assembler code currently does not work on ARM64 */

#          define PNG_ARM_NEON_IMPLEMENTATION 2

#        endif /* __aarch64__ */

#     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

#else /* PNG_ARM_NEON_OPT == 0 */

#     define PNG_ARM_NEON_IMPLEMENTATION 0

#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

#else

#  define PNG_MIPS_MSA_IMPLEMENTATION 0

#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

#else

#  define PNG_POWERPC_VSX_IMPLEMENTATION 0

#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)

#  define png_constcast(type, value) ((type)(void*)(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(__WIN32__) || defined(__NT__)

#  include <windows.h>

#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.

 */

/* Platform-independent functions */

#ifndef PNG_ABORT

#  define PNG_ABORT() abort()

#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 a multiple of 2. */

#ifdef png_alignof

#  define png_isaligned(ptr, type) \

   (((type)(size_t)((const void*)(ptr)) & (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 */

/* 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)

/* 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),