Mirror of roytam1's UXP fork just in case Moonchild and Tobin decide to go after him
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/* pngpriv.h - private declarations for use inside libpng
*
* Last changed in libpng 1.6.26 [October 20, 2016]
* Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
/* The symbols declared in this file (including the functions declared
* as extern) are PRIVATE. They are not part of the libpng public
* interface, and are not recommended for use by regular applications.
* Some of them may become public in the future; others may stay private,
* change in an incompatible way, or even disappear.
* Although the libpng users are not forbidden to include this header,
* they should be well aware of the issues that may arise from doing so.
*/
#ifndef PNGPRIV_H
#define PNGPRIV_H
/* Feature Test Macros. The following are defined here to ensure that correctly
* implemented libraries reveal the APIs libpng needs to build and hide those
* that are not needed and potentially damaging to the compilation.
*
* Feature Test Macros must be defined before any system header is included (see
* POSIX 1003.1 2.8.2 "POSIX Symbols."
*
* These macros only have an effect if the operating system supports either
* POSIX 1003.1 or C99, or both. On other operating systems (particularly
* Windows/Visual Studio) there is no effect; the OS specific tests below are
* still required (as of 2011-05-02.)
*/
#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.
*
* NOTE: at present these optimizations depend on 'ALIGNED_MEMORY', so they
* can only be turned on automatically if that is supported too. If
* PNG_ARM_NEON_OPT is set in CPPFLAGS (to >0) then arm/arm_init.c will fail
* to compile with an appropriate #error if ALIGNED_MEMORY has been turned
* off.
*
* Note that gcc-4.9 defines __ARM_NEON instead of the deprecated
* __ARM_NEON__, so we check both variants.
*
* To disable ARM_NEON optimizations entirely, and skip compiling the
* associated assembler code, pass --enable-arm-neon=no to configure
* or put -DPNG_ARM_NEON_OPT=0 in CPPFLAGS.
*/
# if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
defined(PNG_ALIGNED_MEMORY_SUPPORTED)
# define PNG_ARM_NEON_OPT 2
# else
# define PNG_ARM_NEON_OPT 0
# endif
#endif
#if PNG_ARM_NEON_OPT > 0
/* NEON optimizations are to be at least considered by libpng, so enable the
* callbacks to do this.
*/
# define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
/* By default the 'intrinsics' code in arm/filter_neon_intrinsics.c is used
* if possible - if __ARM_NEON__ is set and the compiler version is not known
* to be broken. This is controlled by PNG_ARM_NEON_IMPLEMENTATION which can
* be:
*
* 1 The intrinsics code (the default with __ARM_NEON__)
* 2 The hand coded assembler (the default without __ARM_NEON__)
*
* It is possible to set PNG_ARM_NEON_IMPLEMENTATION in CPPFLAGS, however
* this is *NOT* supported and may cease to work even after a minor revision
* to libpng. It *is* valid to do this for testing purposes, e.g. speed
* testing or a new compiler, but the results should be communicated to the
* libpng implementation list for incorporation in the next minor release.
*/
# ifndef PNG_ARM_NEON_IMPLEMENTATION
# if defined(__ARM_NEON__) || defined(__ARM_NEON)
# if defined(__clang__)
/* At present it is unknown by the libpng developers which versions
* of clang support the intrinsics, however some or perhaps all
* versions do not work with the assembler so this may be
* irrelevant, so just use the default (do nothing here.)
*/
# elif defined(__GNUC__)
/* GCC 4.5.4 NEON support is known to be broken. 4.6.3 is known to
* work, so if this *is* GCC, or G++, look for a version >4.5
*/
# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
# define PNG_ARM_NEON_IMPLEMENTATION 2
# endif /* no GNUC support */
# endif /* __GNUC__ */
# else /* !defined __ARM_NEON__ */
/* The 'intrinsics' code simply won't compile without this -mfpu=neon:
*/
# define PNG_ARM_NEON_IMPLEMENTATION 2
# endif /* __ARM_NEON__ */
# endif /* !PNG_ARM_NEON_IMPLEMENTATION */
# ifndef PNG_ARM_NEON_IMPLEMENTATION
/* Use the intrinsics code by default. */
# define PNG_ARM_NEON_IMPLEMENTATION 1
# endif
#endif /* PNG_ARM_NEON_OPT > 0 */
#ifndef PNG_MIPS_MSA_OPT
# if defined(__mips_msa) && (__mips_isa_rev >= 5) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
# define PNG_MIPS_MSA_OPT 2
# else
# define PNG_MIPS_MSA_OPT 0
# endif
#endif
#ifndef PNG_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
# endif
# 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
#endif
#if PNG_MIPS_MSA_OPT > 0
# define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_msa
# ifndef PNG_MIPS_MSA_IMPLEMENTATION
# if defined(__mips_msa)
# if defined(__clang__)
# elif defined(__GNUC__)
# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
# define PNG_MIPS_MSA_IMPLEMENTATION 2
# endif /* no GNUC support */
# endif /* __GNUC__ */
# else /* !defined __mips_msa */
# define PNG_MIPS_MSA_IMPLEMENTATION 2
# endif /* __mips_msa */
# endif /* !PNG_MIPS_MSA_IMPLEMENTATION */
# ifndef PNG_MIPS_MSA_IMPLEMENTATION
# define PNG_MIPS_MSA_IMPLEMENTATION 1
# endif
#endif /* PNG_MIPS_MSA_OPT > 0 */
/* 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
/* 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)\
(((type)((const char*)ptr-(const char*)0) & \
(type)(png_alignof(type)-1)) == 0)
#else
# define png_isaligned(ptr, type) 0
#endif
/* End of memory model/platform independent support */
/* End of 1.5.0beta36 move from pngconf.h */
/* CONSTANTS and UTILITY MACROS
* These are used internally by libpng and not exposed in the API
*/
/* Various modes of operation. Note that after an init, mode is set to
* zero automatically when the structure is created. Three of these
* are defined in png.h because they need to be visible to applications
* that call png_set_unknown_chunk().
*/
/* #define PNG_HAVE_IHDR 0x01U (defined in png.h) */
/* #define PNG_HAVE_PLTE 0x02U (defined in png.h) */
#define PNG_HAVE_IDAT 0x04U
/* #define PNG_AFTER_IDAT 0x08U (defined in png.h) */
#define PNG_HAVE_IEND 0x10U
/* 0x20U (unused) */
/* 0x40U (unused) */
/* 0x80U (unused) */
#define PNG_HAVE_CHUNK_HEADER 0x100U
#define PNG_WROTE_tIME 0x200U
#define PNG_WROTE_INFO_BEFORE_PLTE 0x400U
#define PNG_BACKGROUND_IS_GRAY 0x800U
#define PNG_HAVE_PNG_SIGNATURE 0x1000U
#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000U /* Have another chunk after IDAT */
/* 0x4000U (unused) */
#define PNG_IS_READ_STRUCT 0x8000U /* Else is a write struct */
#ifdef PNG_APNG_SUPPORTED
#define PNG_HAVE_acTL 0x10000U
#define PNG_HAVE_fcTL 0x20000U
#endif
/* Flags for the transformations the PNG library does on the image data */
#define PNG_BGR 0x0001U
#define PNG_INTERLACE 0x0002U
#define PNG_PACK 0x0004U
#define PNG_SHIFT 0x0008U
#define PNG_SWAP_BYTES 0x0010U
#define PNG_INVERT_MONO 0x0020U
#define PNG_QUANTIZE 0x0040U
#define PNG_COMPOSE 0x0080U /* Was PNG_BACKGROUND */
#define PNG_BACKGROUND_EXPAND 0x0100U
#define PNG_EXPAND_16 0x0200U /* Added to libpng 1.5.2 */
#define PNG_16_TO_8 0x0400U /* Becomes 'chop' in 1.5.4 */
#define PNG_RGBA 0x0800U
#define PNG_EXPAND 0x1000U
#define PNG_GAMMA 0x2000U
#define PNG_GRAY_TO_RGB 0x4000U
#define PNG_FILLER 0x8000U
#define PNG_PACKSWAP 0x10000U
#define PNG_SWAP_ALPHA 0x20000U
#define PNG_STRIP_ALPHA 0x40000U
#define PNG_INVERT_ALPHA 0x80000U
#define PNG_USER_TRANSFORM 0x100000U
#define PNG_RGB_TO_GRAY_ERR 0x200000U
#define PNG_RGB_TO_GRAY_WARN 0x400000U
#define PNG_RGB_TO_GRAY 0x600000U /* two bits, RGB_TO_GRAY_ERR|WARN */
#define PNG_ENCODE_ALPHA 0x800000U /* Added to libpng-1.5.4 */
#define PNG_ADD_ALPHA 0x1000000U /* Added to libpng-1.2.7 */
#define PNG_EXPAND_tRNS 0x2000000U /* Added to libpng-1.2.9 */
#define PNG_SCALE_16_TO_8 0x4000000U /* Added to libpng-1.5.4 */
/* 0x8000000U unused */
/* 0x10000000U unused */
/* 0x20000000U unused */
/* 0x40000000U unused */
/* Flags for png_create_struct */
#define PNG_STRUCT_PNG 0x0001U
#define PNG_STRUCT_INFO 0x0002U
/* Flags for the png_ptr->flags rather than declaring a byte for each one */
#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY 0x0001U
#define PNG_FLAG_ZSTREAM_INITIALIZED 0x0002U /* Added to libpng-1.6.0 */
/* 0x0004U unused */
#define PNG_FLAG_ZSTREAM_ENDED 0x0008U /* Added to libpng-1.6.0 */
/* 0x0010U unused */
/* 0x0020U unused */
#define PNG_FLAG_ROW_INIT 0x0040U
#define PNG_FLAG_FILLER_AFTER 0x0080U
#define PNG_FLAG_CRC_ANCILLARY_USE 0x0100U
#define PNG_FLAG_CRC_ANCILLARY_NOWARN 0x0200U
#define PNG_FLAG_CRC_CRITICAL_USE 0x0400U
#define PNG_FLAG_CRC_CRITICAL_IGNORE 0x0800U
#define PNG_FLAG_ASSUME_sRGB 0x1000U /* Added to libpng-1.5.4 */
#define PNG_FLAG_OPTIMIZE_ALPHA 0x2000U /* Added to libpng-1.5.4 */
#define PNG_FLAG_DETECT_UNINITIALIZED 0x4000U /* Added to libpng-1.5.4 */
/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS 0x8000U */
/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS 0x10000U */
#define PNG_FLAG_LIBRARY_MISMATCH 0x20000U
#define PNG_FLAG_STRIP_ERROR_NUMBERS 0x40000U
#define PNG_FLAG_STRIP_ERROR_TEXT 0x80000U
#define PNG_FLAG_BENIGN_ERRORS_WARN 0x100000U /* Added to libpng-1.4.0 */
#define PNG_FLAG_APP_WARNINGS_WARN 0x200000U /* Added to libpng-1.6.0 */
#define PNG_FLAG_APP_ERRORS_WARN 0x400000U /* Added to libpng-1.6.0 */
/* 0x800000U unused */
/* 0x1000000U unused */
/* 0x2000000U unused */
/* 0x4000000U unused */
/* 0x8000000U unused */
/* 0x10000000U unused */
/* 0x20000000U unused */
/* 0x40000000U unused */
#define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
PNG_FLAG_CRC_ANCILLARY_NOWARN)
#define PNG_FLAG_CRC_CRITICAL_MASK (PNG_FLAG_CRC_CRITICAL_USE | \
PNG_FLAG_CRC_CRITICAL_IGNORE)
#define PNG_FLAG_CRC_MASK (PNG_FLAG_CRC_ANCILLARY_MASK | \
PNG_FLAG_CRC_CRITICAL_MASK)
/* Save typing and make code easier to understand */
#define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
abs((int)((c1).green) - (int)((c2).green)) + \
abs((int)((c1).blue) - (int)((c2).blue)))
/* Added to libpng-1.6.0: scale a 16-bit value in the range 0..65535 to 0..255
* by dividing by 257 *with rounding*. This macro is exact for the given range.
* See the discourse in pngrtran.c png_do_scale_16_to_8. The values in the
* macro were established by experiment (modifying the added value). The macro
* has a second variant that takes a value already scaled by 255 and divides by
* 65535 - this has a maximum error of .502. Over the range 0..65535*65535 it
* only gives off-by-one errors and only for 0.5% (1 in 200) of the values.
*/
#define PNG_DIV65535(v24) (((v24) + 32895) >> 16)
#define PNG_DIV257(v16) PNG_DIV65535((png_uint_32)(v16) * 255)
/* Added to libpng-1.2.6 JB */
#define PNG_ROWBYTES(pixel_bits, width) \
((pixel_bits) >= 8 ? \
((png_size_t)(width) * (((png_size_t)(pixel_bits)) >> 3)) : \
(( ((png_size_t)(width) * ((png_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_fRAc PNG_U32(102, 82, 65, 99) /* registered, not defined */
#define png_gAMA PNG_U32(103, 65, 77, 65)
#define png_gIFg PNG_U32(103, 73, 70, 103)
#define png_gIFt PNG_U32(103, 73, 70, 116) /* deprecated */
#define png_gIFx PNG_U32(103, 73, 70, 120)
#define png_hIST PNG_U32(104, 73, 83, 84)
#define png_iCCP PNG_U32(105, 67, 67, 80)
#define png_iTXt PNG_U32(105, 84, 88, 116)
#define png_oFFs PNG_U32(111, 70, 70, 115)
#define png_pCAL PNG_U32(112, 67, 65, 76)
#define png_pHYs PNG_U32(112, 72, 89, 115)
#define png_sBIT PNG_U32(115, 66, 73, 84)
#define png_sCAL PNG_U32(115, 67, 65, 76)
#define png_sPLT PNG_U32(115, 80, 76, 84)
#define png_sRGB PNG_U32(115, 82, 71, 66)
#define png_sTER PNG_U32(115, 84, 69, 82)
#define png_tEXt PNG_U32(116, 69, 88, 116)
#define png_tIME PNG_U32(116, 73, 77, 69)
#define png_tRNS PNG_U32(116, 82, 78, 83)
#define png_zTXt PNG_U32(122, 84, 88, 116)
#ifdef PNG_APNG_SUPPORTED
#define png_acTL PNG_U32( 97, 99, 84, 76)
#define png_fcTL PNG_U32(102, 99, 84, 76)
#define png_fdAT PNG_U32(102, 100, 65, 84)
/* For png_struct.apng_flags: */
#define PNG_FIRST_FRAME_HIDDEN 0x0001U
#define PNG_APNG_APP 0x0002U
#endif
/* The following will work on (signed char*) strings, whereas the get_uint_32
* macro will fail on top-bit-set values because of the sign extension.
*/
#define PNG_CHUNK_FROM_STRING(s)\
PNG_U32(0xff & (s)[0], 0xff & (s)[1], 0xff & (s)[2], 0xff & (s)[3])
/* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
* signed and the argument is a (char[]) This macro will fail miserably on
* systems where (char) is more than 8 bits.
*/
#define PNG_STRING_FROM_CHUNK(s,c)\
(void)(((char*)(s))[0]=(char)(((c)>>24) & 0xff), \
((char*)(s))[1]=(char)(((c)>>16) & 0xff),\
((char*)(s))[2]=(char)(((c)>>8) & 0xff), \
((char*)(s))[3]=(char)((c & 0xff)))
/* Do the same but terminate with a null character. */
#define PNG_CSTRING_FROM_CHUNK(s,c)\
(void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)
/* Test on flag values as defined in the spec (section 5.4): */
#define PNG_CHUNK_ANCILLARY(c) (1 & ((c) >> 29))
#define PNG_CHUNK_CRITICAL(c) (!PNG_CHUNK_ANCILLARY(c))
#define PNG_CHUNK_PRIVATE(c) (1 & ((c) >> 21))
#define PNG_CHUNK_RESERVED(c) (1 & ((c) >> 13))
#define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >> 5))
/* Gamma values (new at libpng-1.5.4): */
#define PNG_GAMMA_MAC_OLD 151724 /* Assume '1.8' is really 2.2/1.45! */
#define PNG_GAMMA_MAC_INVERSE 65909
#define PNG_GAMMA_sRGB_INVERSE 45455
/* Almost everything below is C specific; the #defines above can be used in
* non-C code (so long as it is C-preprocessed) the rest of this stuff cannot.
*/
#ifndef PNG_VERSION_INFO_ONLY
#include "pngstruct.h"
#include "pnginfo.h"
/* Validate the include paths - the include path used to generate pnglibconf.h
* must match that used in the build, or we must be using pnglibconf.h.prebuilt:
*/
#if PNG_ZLIB_VERNUM != 0 && PNG_ZLIB_VERNUM != ZLIB_VERNUM
# error ZLIB_VERNUM != PNG_ZLIB_VERNUM \
"-I (include path) error: see the notes in pngpriv.h"
/* This means that when pnglibconf.h was built the copy of zlib.h that it
* used is not the same as the one being used here. Because the build of
* libpng makes decisions to use inflateInit2 and inflateReset2 based on the
* zlib version number and because this affects handling of certain broken
* PNG files the -I directives must match.
*
* The most likely explanation is that you passed a -I in CFLAGS. This will
* not work; all the preprocessor 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)(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, 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.
*/