[master] Imported from libpng-1.6.21.tar

[master] Imported from libpng-1.6.20.tar
[master] Imported from libpng-1.6.19.tar
2025-07-10 18:04:09 +02:00 · 2016-01-15 14:04:53 -06:00 · 2015-12-02 22:37:04 -06:00 · 2015-11-12 07:18:03 -06:00 · 2015-07-22 22:41:05 -05:00 · 2015-03-26 08:11:22 -05:00
53 changed files with 515 additions and 3040 deletions
--- a/120
+++ b/120
@@ -1,103 +1,55 @@
-Libpng 1.6.22beta06 - May 5, 2016
+Libpng 1.6.21 - January 15, 2016

-This is not intended to be a public release.  It will be replaced
-within a few weeks by a public version or by another test version.
+This is a public release of libpng, intended for use in production codes.

 Files available for download:

 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script

-   1.6.22beta06.tar.xz (LZMA-compressed, recommended)
-   1.6.22beta06.tar.gz
+   libpng-1.6.21.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.21.tar.gz

 Source files with CRLF line endings (for Windows), without the
 "configure" script

-   lp1622b06.7z  (LZMA-compressed, recommended)
-   lp1622b06.zip
+   /scratch/glennrp/Libpng16/lpng1621.7z  (LZMA-compressed, recommended)
+   /scratch/glennrp/Libpng16/lpng1621.zip

 Other information:

-   1.6.22beta06-README.txt
-   1.6.22beta06-LICENSE.txt
-   libpng-1.6.22beta06-*.asc (armored detached GPG signatures)
+   libpng-1.6.21-README.txt
+   libpng-1.6.21-LICENSE.txt
+   libpng-1.6.21-*.asc (armored detached GPG signatures)

-Changes since the last public release (1.6.21):
+Changes since the last public release (1.6.20):

-Version 1.6.22beta01 [January 23, 2016]
-  Changed PNG_USE_MKSTEMP to __COVERITY__ to select alternate
-    "tmpfile()" implementation in contrib/libtests/pngstest.c
-  Fixed NO_STDIO build of pngunknown.c to skip calling png_init_io()
-    if there is no stdio.h support.
-  Added a png_image_write_to_memory() API and a number of assist macros
-    to allow an application that uses the simplified API write to bypass
-    stdio and write directly to memory.
-  Added some warnings (png.h) and some check code to detect *possible*
-    overflow in the ROW_STRIDE and simplified image SIZE macros.  This
-    disallows image width/height/format that *might* overflow.  This is
-    a quiet API change that limits in-memory image size (uncompressed) to
-    less than 4GByte and image row size (stride) to less than 2GByte.
-  Revised workaround for false-positive Coverity issue in pngvalid.c.
-
-Version 1.6.22beta02 [February 8, 2016]
-  Only use exit(77) in configure builds.
-  Corrected error in PNG_IMAGE_PNG_SIZE_MAX. This new macro underreported
-    the palette size because it failed to take into account that the memory
-    palette has to be expanded to full RGB when it is written to PNG.
-  Updated CMakeLists.txt, added supporting scripts/gen*.cmake.in
-    and test.cmake.in (Roger Leigh).
-  Relaxed limit checks on gamma values in pngrtran.c. As suggested in
-    the comments gamma values outside the range currently permitted
-    by png_set_alpha_mode are useful for HDR data encoding.  These values
-    are already permitted by png_set_gamma so it is reasonable caution to
-    extend the png_set_alpha_mode range as HDR imaging systems are starting
-    to emerge.
-
-Version 1.6.22beta03 [March 9, 2016]
-  Added a common-law trademark notice and export control information
-    to the LICENSE file, png.h, and the man page.
-  Restored "& 0xff" in png_save_uint_16() and png_save_uint_32() that
-    were accidentally removed from libpng-1.6.17. 
-  Changed PNG_INFO_cHNK and PNG_FREE_cHNK from 0xnnnn to 0xnnnnU in png.h
-    (Robert C. Seacord).
-  Removed dubious "#if INT_MAX" test from png.h that was added to
-    libpng-1.6.19beta02 (John Bowler).
-  Add ${INCLUDES} in scripts/genout.cmake.in (Bug report by Nixon Kwok).
-  Updated LICENSE to say files in the contrib directory are not
-    necessarily under the libpng license, and that some makefiles have
-    other copyright owners.
-  Added INTEL-SSE2 support (Mike Klein and Matt Sarett, Google, Inc.).
-  Made contrib/libtests/timepng more robust.  The code no longer gives
-    up/fails on invalid PNG data, it just skips it (with error messages).
-    The code no longer fails on PNG files with data beyond IEND.  Options
-    exist to use png_read_png (reading the whole image, not by row) and, in
-    that case, to apply any of the supported transforms.  This makes for
-    more realistic testing; the decoded data actually gets used in a
-    meaningful fashion (John Bowler).
-  Fixed some misleading indentation (Krishnaraj Bhat).
-
-Version 1.6.22beta04 [April 5, 2016]
-  Force GCC compilation to C89 if needed (Dagobert Michelsen).
-  SSE filter speed improvements for bpp=3:
-    memcpy-free implementations of load3() / store3().
-    call load3() only when needed at the end of a scanline.
-
-Version 1.6.22beta05 [April 27, 2016]
-  Added PNG_FAST_FILTERS macro (defined as
-    PNG_FILTER_NONE|PNG_FILTER_SUB|PNG_FILTER_UP).
-  Various fixes for contrib/libtests/timepng.c
-  Moved INTEL-SSE code from pngpriv.h into contrib/intel/intel_sse.patch.
-  Fixed typo (missing underscore) in #define PNG_READ_16_TO_8_SUPPORTED
-    (Bug report by Y.Ohashik).
-
-Version 1.6.22beta06 [May 5, 2016]
-  Rebased contrib/intel_sse.patch.
-  Quieted two Coverity issues in contrib/libtests/timepng.c.
-  Fixed issues with scripts/genout.cmake.in (David Capello, Nixon Kwok):
-    Added support to use multiple directories in ZLIBINCDIR variable,
-    Fixed CMAKE_C_FLAGS with multiple values when genout is compiled on MSVC,
-    Fixed pnglibconf.c compilation on OS X including the sysroot path.
+  Fixed syntax "$(command)" in tests/pngstest that some shells other than
+    bash could not parse (Bug report by Nelson Beebe). Use `command` instead.
+  Moved png_check_keyword() from pngwutil.c to pngset.c
+  Removed LE/BE dependencies in pngvalid, to 'fix' the current problem
+    in the BigEndian tests by not testing it, making the BE code the same 
+    as the LE version.
+  Fixes to pngvalid for various reduced build configurations (eliminate unused
+    statics) and a fix for the case in rgb_to_gray when the digitize option
+    reduces graylo to 0, producing a large error.
+  Widened the 'limit' check on the internally calculated error limits in
+    the 'DIGITIZE' case (the code used prior to 1.7 for rgb_to_gray error
+    checks) and changed the check to only operate in non-release builds
+   (base build type not RC or RELEASE.)
+  Fixed undefined behavior in pngvalid.c, undefined because
+    (png_byte) << shift is undefined if it changes the signed bit
+    (because png_byte is promoted to int). The libpng exported functions
+    png_get_uint_32 and png_get_uint_16 handle this. (Bug reported by
+    David Drysdale as a result of reports from UBSAN in clang 3.8).
+  This changes pngvalid to use BE random numbers; this used to produce
+    errors but these should not be fixed as a result of the previous changes.
+  In projects/vstudio, combined readme.txt and WARNING into README.txt
+  Relocated assert() in contrib/tools/pngfix.c, bug found by American
+    Fuzzy Lop, reported by Brian Carpenter.
+  Marked 'limit' UNUSED in transform_range_check().  This only affects
+    release builds.
+  Worked around a false-positive Coverity issue in pngvalid.c.

 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
--- a/77
+++ b/77
@@ -5063,8 +5063,7 @@ Version 1.6.15beta04 [November 4, 2014]
 Version 1.6.15beta05 [November 5, 2014]
  Use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING in
    example.c, pngtest.c, and applications in the contrib directory.
-  Fixed an out-of-range read in png_user_version_check() (Bug report from
-    Qixue Xiao, CVE-2015-8540).
+  Avoid out-of-bounds memory access in png_user_version_check().
  Simplified and future-proofed png_user_version_check().
  Fixed GCC unsigned int->float warnings. Various versions of GCC
    seem to generate warnings when an unsigned value is implicitly
@@ -5485,80 +5484,6 @@ Version 1.6.21rc02 [January 7, 2016]
 Version 1.6.21 [January 15, 2016]
  Worked around a false-positive Coverity issue in pngvalid.c.

-Version 1.6.22beta01 [January 23, 2016]
-  Changed PNG_USE_MKSTEMP to __COVERITY__ to select alternate
-    "tmpfile()" implementation in contrib/libtests/pngstest.c
-  Fixed NO_STDIO build of pngunknown.c to skip calling png_init_io()
-    if there is no stdio.h support.
-  Added a png_image_write_to_memory() API and a number of assist macros
-    to allow an application that uses the simplified API write to bypass
-    stdio and write directly to memory.
-  Added some warnings (png.h) and some check code to detect *possible*
-    overflow in the ROW_STRIDE and simplified image SIZE macros.  This
-    disallows image width/height/format that *might* overflow.  This is
-    a quiet API change that limits in-memory image size (uncompressed) to
-    less than 4GByte and image row size (stride) to less than 2GByte.
-  Revised workaround for false-positive Coverity issue in pngvalid.c.
-
-Version 1.6.22beta02 [February 8, 2016]
-  Only use exit(77) in configure builds.
-  Corrected error in PNG_IMAGE_PNG_SIZE_MAX. This new macro underreported
-    the palette size because it failed to take into account that the memory
-    palette has to be expanded to full RGB when it is written to PNG.
-  Updated CMakeLists.txt, added supporting scripts/gen*.cmake.in
-    and test.cmake.in (Roger Leigh).
-  Relaxed limit checks on gamma values in pngrtran.c. As suggested in
-    the comments gamma values outside the range currently permitted
-    by png_set_alpha_mode are useful for HDR data encoding.  These values
-    are already permitted by png_set_gamma so it is reasonable caution to
-    extend the png_set_alpha_mode range as HDR imaging systems are starting
-    to emerge.
-
-Version 1.6.22beta03 [March 9, 2016]
-  Added a common-law trademark notice and export control information
-    to the LICENSE file, png.h, and the man page.
-  Restored "& 0xff" in png_save_uint_16() and png_save_uint_32() that
-    were accidentally removed from libpng-1.6.17. 
-  Changed PNG_INFO_cHNK and PNG_FREE_cHNK from 0xnnnn to 0xnnnnU in png.h
-    (Robert C. Seacord).
-  Removed dubious "#if INT_MAX" test from png.h that was added to
-    libpng-1.6.19beta02 (John Bowler).
-  Add ${INCLUDES} in scripts/genout.cmake.in (Bug report by Nixon Kwok).
-  Updated LICENSE to say files in the contrib directory are not
-    necessarily under the libpng license, and that some makefiles have
-    other copyright owners.
-  Added INTEL-SSE2 support (Mike Klein and Matt Sarett, Google, Inc.).
-  Made contrib/libtests/timepng more robust.  The code no longer gives
-    up/fails on invalid PNG data, it just skips it (with error messages).
-    The code no longer fails on PNG files with data beyond IEND.  Options
-    exist to use png_read_png (reading the whole image, not by row) and, in
-    that case, to apply any of the supported transforms.  This makes for
-    more realistic testing; the decoded data actually gets used in a
-    meaningful fashion (John Bowler).
-  Fixed some misleading indentation (Krishnaraj Bhat).
-
-Version 1.6.22beta04 [April 5, 2016]
-  Force GCC compilation to C89 if needed (Dagobert Michelsen).
-  SSE filter speed improvements for bpp=3:
-    memcpy-free implementations of load3() / store3().
-    call load3() only when needed at the end of a scanline.
-
-Version 1.6.22beta05 [April 27, 2016]
-  Added PNG_FAST_FILTERS macro (defined as
-    PNG_FILTER_NONE|PNG_FILTER_SUB|PNG_FILTER_UP).
-  Various fixes for contrib/libtests/timepng.c
-  Moved INTEL-SSE code from pngpriv.h into contrib/intel/intel_sse.patch.
-  Fixed typo (missing underscore) in #define PNG_READ_16_TO_8_SUPPORTED
-    (Bug report by Y.Ohashik).
-
-Version 1.6.22beta06 [May 5, 2016]
-  Rebased contrib/intel_sse.patch.
-  Quieted two Coverity issues in contrib/libtests/timepng.c.
-  Fixed issues with scripts/genout.cmake.in (David Capello, Nixon Kwok):
-    Added support to use multiple directories in ZLIBINCDIR variable,
-    Fixed CMAKE_C_FLAGS with multiple values when genout is compiled on MSVC,
-    Fixed pnglibconf.c compilation on OS X including the sysroot path.
-
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,32 +1,13 @@
 # CMakeLists.txt

-# Copyright (C) 2007,2009-2016 Glenn Randers-Pehrson
-# Written by Christian Ehrlicher, 2007
-# Revised by Roger Lowman, 2009-2010
-# Revised by Clifford Yapp, 2011-2012
-# Revised by Roger Leigh, 2016
+# Copyright (C) 2007-2015 Glenn Randers-Pehrson

 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
 # and license in png.h

-cmake_minimum_required(VERSION 2.8.3)
-cmake_policy(VERSION 2.8.3)
-
-# Set MacOSX @rpath usage globally.
-if (POLICY CMP0020)
-  cmake_policy(SET CMP0020 NEW)
-endif(POLICY CMP0020)
-if (POLICY CMP0042)
-  cmake_policy(SET CMP0042 NEW)
-endif(POLICY CMP0042)
-# Use new variable expansion policy.
-if (POLICY CMP0053)
-  cmake_policy(SET CMP0053 NEW)
-endif(POLICY CMP0053)
-if (POLICY CMP0054)
-  cmake_policy(SET CMP0054 NEW)
-endif(POLICY CMP0054)
+cmake_minimum_required(VERSION 2.4.4)
+set(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true)

 set(CMAKE_CONFIGURATION_TYPES "Release;Debug;MinSizeRel;RelWithDebInfo")

@@ -35,7 +16,7 @@ enable_testing()

 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 22)
+set(PNGLIB_RELEASE 21)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})

@@ -66,284 +47,32 @@ option(PNG_FRAMEWORK "Build OS X framework" OFF)
 option(PNG_DEBUG     "Build with debug output" OFF)
 option(PNGARG        "Disable ANSI-C prototypes" OFF)

-set(PNG_PREFIX "" CACHE STRING "Prefix to add to the API function names")
-set(DFA_XTRA "" CACHE FILEPATH "File containing extra configuration settings")
-
 # SET LIBNAME
 set(PNG_LIB_NAME png${PNGLIB_MAJOR}${PNGLIB_MINOR})

 # to distinguish between debug and release lib
 set(CMAKE_DEBUG_POSTFIX "d")

-include(CheckCSourceCompiles)
-option(ld-version-script "Enable linker version script" ON)
-if(ld-version-script AND NOT APPLE)
-  # Check if LD supports linker scripts.
-  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/conftest.map" "VERS_1 {
-        global: sym;
-        local: *;
-};
-
-VERS_2 {
-        global: sym2;
-                main;
-} VERS_1;
-")
-  set(CMAKE_REQUIRED_FLAGS_SAVE ${CMAKE_REQUIRED_FLAGS})
-  set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS} "-Wl,--version-script='${CMAKE_CURRENT_BINARY_DIR}/conftest.map'")
-  check_c_source_compiles("void sym(void) {}
-void sym2(void) {}
-int main(void) {return 0;}
-" HAVE_LD_VERSION_SCRIPT)
-  if(NOT HAVE_LD_VERSION_SCRIPT)
-    set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS_SAVE} "-Wl,-M -Wl,${CMAKE_CURRENT_BINARY_DIR}/conftest.map")
-  check_c_source_compiles("void sym(void) {}
-void sym2(void) {}
-int main(void) {return 0;}
-" HAVE_SOLARIS_LD_VERSION_SCRIPT)
-  endif()
-  set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS_SAVE})
-  file(REMOVE "${CMAKE_CURRENT_BINARY_DIR}/conftest.map")
-endif()
-
-# Find symbol prefix.  Likely obsolete and unnecessary with recent
-# toolchains (it's not done in many other projects).
-function(symbol_prefix)
-  set(SYMBOL_PREFIX)
-
-  execute_process(COMMAND "${CMAKE_C_COMPILER}" "-E" "-"
-                  INPUT_FILE /dev/null
-                  OUTPUT_VARIABLE OUT
-                  RESULT_VARIABLE STATUS)
-
-  if(CPP_FAIL)
-    message(WARNING "Failed to run the C preprocessor")
-  endif()
-
-  string(REPLACE "\n" ";" OUT "${OUT}")
-  foreach(line ${OUT})
-    string(REGEX MATCH "^PREFIX=" found_match "${line}")
-    if(found_match)
-      STRING(REGEX REPLACE "^PREFIX=(.*\)" "\\1" prefix "${line}")
-      string(REGEX MATCH "__USER_LABEL_PREFIX__" found_match "${prefix}")
-      if(found_match)
-        STRING(REGEX REPLACE "(.*)__USER_LABEL_PREFIX__(.*)" "\\1\\2" prefix "${prefix}")
-      endif()
-      set(SYMBOL_PREFIX "${prefix}")
-    endif()
-  endforeach()
-
-    message(STATUS "Symbol prefix: ${SYMBOL_PREFIX}")
-    set(SYMBOL_PREFIX "${SYMBOL_PREFIX}" PARENT_SCOPE)
-endfunction()
-
-if(UNIX)
-  symbol_prefix()
-endif()
-
-find_program(AWK NAMES gawk awk)
-
+# Use the prebuilt pnglibconf.h file from the scripts folder
+# TODO: fix this by building with awk; without this no cmake build can be
+# configured directly (to do so indirectly use your local awk to build a
+# pnglibconf.h in the build directory.)
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
+               ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
 include_directories(${CMAKE_CURRENT_BINARY_DIR})

-if(NOT AWK)
-  # No awk available to generate sources; use pre-built pnglibconf.h
-  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
-                 ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
-  add_custom_target(genfiles) # Dummy
-else()
-  include(CMakeParseArguments)
-  # Generate .chk from .out with awk
-  # generate_chk(INPUT inputfile OUTPUT outputfile [DEPENDS dep1 [dep2...]])
-  function(generate_chk)
-    set(options)
-    set(oneValueArgs INPUT OUTPUT)
-    set(multiValueArgs DEPENDS)
-    cmake_parse_arguments(_GC "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GC_INPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires input.")
-    endif()
-    if (NOT _GC_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires output.")
-    endif()
-
-    add_custom_command(OUTPUT "${_GC_OUTPUT}"
-                       COMMAND "${CMAKE_COMMAND}"
-                               "-DINPUT=${_GC_INPUT}"
-                               "-DOUTPUT=${_GC_OUTPUT}"
-                               -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/genchk.cmake"
-                       DEPENDS "${_GC_INPUT}" ${_GC_DEPENDS}
-                       WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-  endfunction()
-
-  # Generate .out from .c with awk
-  # generate_out(INPUT inputfile OUTPUT outputfile [DEPENDS dep1 [dep2...]])
-  function(generate_out)
-    set(options)
-    set(oneValueArgs INPUT OUTPUT)
-    set(multiValueArgs DEPENDS)
-    cmake_parse_arguments(_GO "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GO_INPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires input.")
-    endif()
-    if (NOT _GO_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires output.")
-    endif()
-
-    add_custom_command(OUTPUT "${_GO_OUTPUT}"
-                       COMMAND "${CMAKE_COMMAND}"
-                               "-DINPUT=${_GO_INPUT}"
-                               "-DOUTPUT=${_GO_OUTPUT}"
-                               -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/genout.cmake"
-                       DEPENDS "${_GO_INPUT}" ${_GO_DEPENDS}
-                       WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-  endfunction()
-
-  # Generate specific source file with awk
-  # generate_source(OUTPUT outputfile [DEPENDS dep1 [dep2...]])
-  function(generate_source)
-    set(options)
-    set(oneValueArgs OUTPUT)
-    set(multiValueArgs DEPENDS)
-    cmake_parse_arguments(_GSO "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GSO_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_source requires output.")
-    endif()
-
-    add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${_GSO_OUTPUT}"
-                       COMMAND "${CMAKE_COMMAND}"
-                               "-DOUTPUT=${_GSO_OUTPUT}"
-                               -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/gensrc.cmake"
-                       DEPENDS ${_GSO_DEPENDS}
-                       WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-  endfunction()
-
-  # Copy file
-  function(generate_copy source destination)
-    add_custom_command(OUTPUT "${destination}"
-                       COMMAND "${CMAKE_COMMAND}" -E remove "${destination}"
-                       COMMAND "${CMAKE_COMMAND}" -E copy "${source}"
-                                                          "${destination}"
-                       DEPENDS "${source}")
-  endfunction()
-
-  # Generate scripts/pnglibconf.h
-  generate_source(OUTPUT "scripts/pnglibconf.c"
-                  DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.dfa"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/scripts/options.awk"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h")
-
-  # Generate pnglibconf.c
-  generate_source(OUTPUT "pnglibconf.c"
-                  DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.dfa"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/scripts/options.awk"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h")
-
-  if(PNG_PREFIX)
-    set(PNGLIBCONF_H_EXTRA_DEPENDS
-        "${CMAKE_CURRENT_BINARY_DIR}/scripts/prefix.out"
-        "${CMAKE_CURRENT_SOURCE_DIR}/scripts/macro.lst")
-    set(PNGPREFIX_H_EXTRA_DEPENDS
-        "${CMAKE_CURRENT_BINARY_DIR}/scripts/intprefix.out")
-  endif()
-
-  generate_out(INPUT "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out")
-
-  # Generate pnglibconf.h
-  generate_source(OUTPUT "pnglibconf.h"
-                  DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out"
-                          ${PNGLIBCONF_H_EXTRA_DEPENDS})
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/intprefix.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/intprefix.out"
-               DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h")
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/prefix.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/prefix.out"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/png.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h"
-                       "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out")
-
-  # Generate pngprefix.h
-  generate_source(OUTPUT "pngprefix.h"
-                  DEPENDS ${PNGPREFIX_H_EXTRA_DEPENDS})
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/sym.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/sym.out"
-               DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h")
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/symbols.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/png.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt")
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/vers.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/png.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h"
-                       "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h")
-
-  generate_chk(INPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/scripts/checksym.awk"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/scripts/symbols.def")
-
-  add_custom_target(symbol-check DEPENDS
-                    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk")
-
-  generate_copy("${CMAKE_CURRENT_BINARY_DIR}/scripts/sym.out"
-                "${CMAKE_CURRENT_BINARY_DIR}/libpng.sym")
-  generate_copy("${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out"
-                "${CMAKE_CURRENT_BINARY_DIR}/libpng.vers")
-
-  add_custom_target(genvers DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/libpng.vers")
-  add_custom_target(gensym DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/libpng.sym")
-
-  add_custom_target("genprebuilt"
-                    COMMAND "${CMAKE_COMMAND}"
-                            "-DOUTPUT=scripts/pnglibconf.h.prebuilt"
-                            -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/gensrc.cmake"
-                    WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-
-  # A single target handles generation of all generated files.  If
-  # they are dependend upon separately by multiple targets, this
-  # confuses parallel make (it would require a separate top-level
-  # target for each file to track the dependencies properly).
-  add_custom_target(genfiles DEPENDS
-    "${CMAKE_CURRENT_BINARY_DIR}/libpng.sym"
-    "${CMAKE_CURRENT_BINARY_DIR}/libpng.vers"
-    "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.c"
-    "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h"
-    "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/pngprefix.h"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/intprefix.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/pnglibconf.c"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/prefix.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/sym.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out")
-endif(NOT AWK)
-
 # OUR SOURCES
 set(libpng_public_hdrs
  png.h
  pngconf.h
-  "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h"
+  ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h
 )
-set(libpng_private_hdrs
-  pngpriv.h
-  pngdebug.h
-  pnginfo.h
-  pngstruct.h
-)
-if(AWK)
-  list(APPEND libpng_private_hdrs "${CMAKE_CURRENT_BINARY_DIR}/pngprefix.h")
-endif()
 set(libpng_sources
  ${libpng_public_hdrs}
-  ${libpng_private_hdrs}
+  pngdebug.h
+  pnginfo.h
+  pngpriv.h
+  pngstruct.h
  png.c
  pngerror.c
  pngget.c
@@ -369,18 +98,7 @@ set(pngvalid_sources
 set(pngstest_sources
  contrib/libtests/pngstest.c
 )
-set(pngunknown_sources
-  contrib/libtests/pngunknown.c
-)
-set(pngimage_sources
-  contrib/libtests/pngimage.c
-)
-set(pngfix_sources
-  contrib/tools/pngfix.c
-)
-set(png_fix_itxt_sources
-  contrib/tools/png-fix-itxt.c
-)
+# SOME NEEDED DEFINITIONS

 if(MSVC)
  add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
@@ -396,59 +114,33 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${ZLIB_INCLUDE_DIR})
 unset(PNG_LIB_TARGETS)

 if(PNG_SHARED)
-  add_library(png SHARED ${libpng_sources})
-  set(PNG_LIB_TARGETS png)
-  set_target_properties(png PROPERTIES OUTPUT_NAME ${PNG_LIB_NAME})
-  add_dependencies(png genfiles)
+  add_library(${PNG_LIB_NAME} SHARED ${libpng_sources})
+  set(PNG_LIB_TARGETS ${PNG_LIB_NAME})
  if(MSVC)
    # msvc does not append 'lib' - do it here to have consistent name
-    set_target_properties(png PROPERTIES PREFIX "lib")
-    set_target_properties(png PROPERTIES IMPORT_PREFIX "lib")
-  endif()
-  target_link_libraries(png ${ZLIB_LIBRARY} ${M_LIBRARY})
-
-  if(UNIX AND AWK)
-    if(HAVE_LD_VERSION_SCRIPT)
-      set_target_properties(png PROPERTIES LINK_FLAGS
-        "-Wl,--version-script='${CMAKE_CURRENT_BINARY_DIR}/libpng.vers'")
-    elseif(HAVE_SOLARIS_LD_VERSION_SCRIPT)
-      set_target_properties(png PROPERTIES LINK_FLAGS
-        "-Wl,-M -Wl,'${CMAKE_CURRENT_BINARY_DIR}/libpng.vers'")
-    endif()
+    set_target_properties(${PNG_LIB_NAME} PROPERTIES PREFIX "lib")
+    set_target_properties(${PNG_LIB_NAME} PROPERTIES IMPORT_PREFIX "lib")
  endif()
+  target_link_libraries(${PNG_LIB_NAME} ${ZLIB_LIBRARY} ${M_LIBRARY})
 endif()

 if(PNG_STATIC)
  # does not work without changing name
-  set(PNG_LIB_NAME_STATIC png_static)
-  add_library(png_static STATIC ${libpng_sources})
-  add_dependencies(png_static genfiles)
-  # MSVC doesn't use a different file extension for shared vs. static
-  # libs.  We are able to change OUTPUT_NAME to remove the _static
-  # for all other platforms.
-  if(NOT MSVC)
-    set_target_properties(png_static PROPERTIES
-      OUTPUT_NAME "${PNG_LIB_NAME}"
-      CLEAN_DIRECT_OUTPUT 1)
-  else()
-    set_target_properties(png_static PROPERTIES
-      OUTPUT_NAME "${PNG_LIB_NAME}_static"
-      CLEAN_DIRECT_OUTPUT 1)
-  endif()
-  list(APPEND PNG_LIB_TARGETS png_static)
+  set(PNG_LIB_NAME_STATIC ${PNG_LIB_NAME}_static)
+  add_library(${PNG_LIB_NAME_STATIC} STATIC ${libpng_sources})
+  list(APPEND PNG_LIB_TARGETS ${PNG_LIB_NAME_STATIC})
  if(MSVC)
    # msvc does not append 'lib' - do it here to have consistent name
-    set_target_properties(png_static PROPERTIES PREFIX "lib")
+    set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES PREFIX "lib")
  endif()
-  target_link_libraries(png_static ${ZLIB_LIBRARY} ${M_LIBRARY})
+  target_link_libraries(${PNG_LIB_NAME_STATIC} ${ZLIB_LIBRARY} ${M_LIBRARY})
 endif()

 if(PNG_FRAMEWORK)
-  set(PNG_LIB_NAME_FRAMEWORK png_framework)
-  add_library(png_framework SHARED ${libpng_sources})
-  add_dependencies(png_framework genfiles)
-  list(APPEND PNG_LIB_TARGETS png_framework)
-  set_target_properties(png_framework PROPERTIES
+  set(PNG_LIB_NAME_FRAMEWORK ${PNG_LIB_NAME}_framework)
+  add_library(${PNG_LIB_NAME_FRAMEWORK} SHARED ${libpng_sources})
+  list(APPEND PNG_LIB_TARGETS ${PNG_LIB_NAME_FRAMEWORK})
+  set_target_properties(${PNG_LIB_NAME_FRAMEWORK} PROPERTIES
    FRAMEWORK TRUE
    FRAMEWORK_VERSION ${PNGLIB_VERSION}
    MACOSX_FRAMEWORK_SHORT_VERSION_STRING ${PNGLIB_MAJOR}.${PNGLIB_MINOR}
@@ -457,7 +149,7 @@ if(PNG_FRAMEWORK)
    XCODE_ATTRIBUTE_INSTALL_PATH "@rpath"
    PUBLIC_HEADER "${libpng_public_hdrs}"
    OUTPUT_NAME png)
-  target_link_libraries(png_framework ${ZLIB_LIBRARY} ${M_LIBRARY})
+  target_link_libraries(${PNG_LIB_NAME_FRAMEWORK} ${ZLIB_LIBRARY} ${M_LIBRARY})
 endif()

 if(NOT PNG_LIB_TARGETS)
@@ -468,170 +160,52 @@ if(NOT PNG_LIB_TARGETS)
 endif()

 if(PNG_SHARED AND WIN32)
-  set_target_properties(png PROPERTIES DEFINE_SYMBOL PNG_BUILD_DLL)
+  set_target_properties(${PNG_LIB_NAME} PROPERTIES DEFINE_SYMBOL PNG_BUILD_DLL)
 endif()

-function(png_add_test)
-  set(options)
-  set(oneValueArgs NAME COMMAND)
-  set(multiValueArgs OPTIONS FILES)
-  cmake_parse_arguments(_PAT "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-
-  if (NOT _PAT_NAME)
-    message(FATAL_ERROR "Invalid arguments.  png_add_test requires name.")
-  endif()
-  if (NOT _PAT_COMMAND)
-    message(FATAL_ERROR "Invalid arguments.  png_add_test requires command.")
-  endif()
-
-  set(TEST_OPTIONS "${_PAT_OPTIONS}")
-  set(TEST_FILES "${_PAT_FILES}")
-
-  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/scripts/test.cmake.in"
-                 "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake" @ONLY)
-  if(CMAKE_MAJOR_VERSION GREATER 2) # have generator expressions
-    add_test(NAME "${_PAT_NAME}"
-             COMMAND "${CMAKE_COMMAND}"
-             "-DLIBPNG=$<TARGET_FILE:png>"
-             "-DTEST_COMMAND=$<TARGET_FILE:${_PAT_COMMAND}>"
-             -P "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake")
-  else() # old 2.x add_test; limited and won't work well on Windows
-    # Note LIBPNG is a dummy value as there are no generator expressions
-    add_test("${_PAT_NAME}" "${CMAKE_COMMAND}"
-             "-DLIBPNG=${CMAKE_CURRENT_BINARY_DIR}/libpng.so"
-             "-DTEST_COMMAND=./${_PAT_COMMAND}"
-             -P "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake")
-  endif()
-endfunction()
-
 if(PNG_TESTS AND PNG_SHARED)
-  # Find test PNG files by globbing, but sort lists to ensure
-  # consistency between different filesystems.
-  file(GLOB PNGSUITE_PNGS "${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/*.png")
-  list(SORT PNGSUITE_PNGS)
-  file(GLOB TEST_PNGS "${CMAKE_CURRENT_SOURCE_DIR}/contrib/testpngs/*.png")
-  list(SORT TEST_PNGS)
-
-  set(PNGTEST_PNG "${CMAKE_CURRENT_SOURCE_DIR}/pngtest.png")
-
+  # does not work with msvc due to png_lib_ver issue
  add_executable(pngtest ${pngtest_sources})
-  target_link_libraries(pngtest png)
-
-  png_add_test(NAME pngtest COMMAND pngtest FILES "${PNGTEST_PNG}")
-
+  target_link_libraries(pngtest ${PNG_LIB_NAME})
+  add_test(pngtest ./pngtest ${CMAKE_CURRENT_SOURCE_DIR}/pngtest.png)
+  #
  add_executable(pngvalid ${pngvalid_sources})
-  target_link_libraries(pngvalid png)
-
-  png_add_test(NAME pngvalid-gamma-16-to-8
-               COMMAND pngvalid OPTIONS --gamma-16-to-8)
-  png_add_test(NAME pngvalid-gamma-alpha-mode
-               COMMAND pngvalid OPTIONS --gamma-alpha-mode)
-  png_add_test(NAME pngvalid-gamma-background
-               COMMAND pngvalid OPTIONS --gamma-background)
-  png_add_test(NAME pngvalid-gamma-expand16-alpha-mode
-               COMMAND pngvalid OPTIONS --gamma-alpha-mode --expand16)
-  png_add_test(NAME pngvalid-gamma-expand16-background
-               COMMAND pngvalid OPTIONS --gamma-background --expand16)
-  png_add_test(NAME pngvalid-gamma-expand16-transform
-               COMMAND pngvalid OPTIONS --gamma-transform --expand16)
-  png_add_test(NAME pngvalid-gamma-sbit
-               COMMAND pngvalid OPTIONS --gamma-sbit)
-  png_add_test(NAME pngvalid-gamma-threshold
-               COMMAND pngvalid OPTIONS --gamma-threshold)
-  png_add_test(NAME pngvalid-gamma-transform
-               COMMAND pngvalid OPTIONS --gamma-transform)
-  png_add_test(NAME pngvalid-progressive-interlace-standard
-               COMMAND pngvalid OPTIONS --standard --progressive-read --interlace)
-  png_add_test(NAME pngvalid-progressive-size
-               COMMAND pngvalid OPTIONS --size --progressive-read)
-  png_add_test(NAME pngvalid-progressive-standard
-               COMMAND pngvalid OPTIONS --standard --progressive-read)
-  png_add_test(NAME pngvalid-standard
-               COMMAND pngvalid OPTIONS --standard)
-  png_add_test(NAME pngvalid-transform
-               COMMAND pngvalid OPTIONS --transform)
-
+  target_link_libraries(pngvalid ${PNG_LIB_NAME})
+  add_test(pngvalid ./pngvalid)
  add_executable(pngstest ${pngstest_sources})
-  target_link_libraries(pngstest png)
-
-  foreach(gamma_type 1.8 linear none sRGB)
-    foreach(alpha_type none alpha)
-      set(PNGSTEST_FILES)
-      foreach(test_png ${TEST_PNGS})
-        string(REGEX MATCH ".*-linear[-.].*" TEST_PNG_LINEAR "${test_png}")
-        string(REGEX MATCH ".*-sRGB[-.].*" TEST_PNG_SRGB "${test_png}")
-        string(REGEX MATCH ".*-1.8[-.].*" TEST_PNG_G18 "${test_png}")
-        string(REGEX MATCH ".*-alpha-.*" TEST_PNG_ALPHA "${test_png}")
-
-        set(TEST_PNG_VALID TRUE)
-
-        if(TEST_PNG_ALPHA)
-          if (NOT "${alpha_type}" STREQUAL "alpha")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        else()
-          if ("${alpha_type}" STREQUAL "alpha")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        endif()
-
-        if(TEST_PNG_LINEAR)
-          if(NOT "${gamma_type}" STREQUAL "linear")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        elseif(TEST_PNG_SRGB)
-          if(NOT "${gamma_type}" STREQUAL "sRGB")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        elseif(TEST_PNG_G18)
-          if(NOT "${gamma_type}" STREQUAL "1.8")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        else()
-          if(NOT "${gamma_type}" STREQUAL "none")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        endif()
-
-        if(TEST_PNG_VALID)
-          list(APPEND PNGSTEST_FILES "${test_png}")
-        endif()
-      endforeach()
-      # Should already be sorted, but sort anyway to be certain.
-      list(SORT PNGSTEST_FILES)
-      png_add_test(NAME pngstest-${gamma_type}-${alpha_type}
-                   COMMAND pngstest
-                   OPTIONS --tmpfile "${gamma_type}-${alpha_type}-" --log
-                   FILES ${PNGSTEST_FILES})
-    endforeach()
-  endforeach()
-
-  add_executable(pngunknown ${pngunknown_sources})
-  target_link_libraries(pngunknown png)
-
-  png_add_test(NAME pngunknown-discard COMMAND pngunknown OPTIONS --strict default=discard FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-IDAT COMMAND pngunknown OPTIONS --strict default=discard IDAT=save FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-if-safe COMMAND pngunknown OPTIONS --strict default=if-safe FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-sAPI COMMAND pngunknown OPTIONS --strict bKGD=save cHRM=save gAMA=save all=discard iCCP=save sBIT=save sRGB=save FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-save COMMAND pngunknown OPTIONS --strict default=save FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-sTER COMMAND pngunknown OPTIONS --strict sTER=if-safe FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-vpAg COMMAND pngunknown OPTIONS --strict vpAg=if-safe FILES "${PNGTEST_PNG}")
-
-  add_executable(pngimage ${pngimage_sources})
-  target_link_libraries(pngimage png)
-
-  png_add_test(NAME pngimage-quick COMMAND pngimage OPTIONS --list-combos --log FILES ${PNGSUITE_PNGS})
-  png_add_test(NAME pngimage-full COMMAND pngimage OPTIONS --exhaustive --list-combos --log FILES ${PNGSUITE_PNGS})
-endif()
-
-if(PNG_SHARED)
-  add_executable(pngfix ${pngfix_sources})
-  target_link_libraries(pngfix png)
-  set(PNG_BIN_TARGETS pngfix)
-
-  add_executable(png-fix-itxt ${png_fix_itxt_sources})
-  target_link_libraries(png-fix-itxt ${ZLIB_LIBRARY} ${M_LIBRARY})
-  list(APPEND PNG_BIN_TARGETS png-fix-itxt)
+  target_link_libraries(pngstest ${PNG_LIB_NAME})
+  add_test(pngstest ./pngstest
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g01.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g02.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g04.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p01.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p02.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p04.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g01.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g02.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g04.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn2c16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn2c16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbrn2c08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn0g16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbyn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n0g08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n2c08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp1n3p08.png
+  )
 endif()

 # Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set
@@ -660,15 +234,6 @@ macro(CREATE_SYMLINK SRC_FILE DEST_FILE)
  endif(WIN32 AND NOT CYGWIN AND NOT MSYS)
 endmacro()

-# Create source generation scripts.
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/genchk.cmake.in
-               ${CMAKE_CURRENT_BINARY_DIR}/scripts/genchk.cmake @ONLY)
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/genout.cmake.in
-               ${CMAKE_CURRENT_BINARY_DIR}/scripts/genout.cmake @ONLY)
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/gensrc.cmake.in
-               ${CMAKE_CURRENT_BINARY_DIR}/scripts/gensrc.cmake @ONLY)
-
-
 # libpng is a library so default to 'lib'
 if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
  set(CMAKE_INSTALL_LIBDIR lib)
@@ -695,12 +260,22 @@ endif(NOT WIN32 OR CYGWIN OR MINGW)

 # SET UP LINKS
 if(PNG_SHARED)
-  set_target_properties(png PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.22beta06
+  set_target_properties(${PNG_LIB_NAME} PROPERTIES
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.21
    VERSION 16.${PNGLIB_RELEASE}.0
    SOVERSION 16
    CLEAN_DIRECT_OUTPUT 1)
 endif()
+if(PNG_STATIC)
+  # MSVC doesn't use a different file extension for shared vs. static
+  # libs.  We are able to change OUTPUT_NAME to remove the _static
+  # for all other platforms.
+  if(NOT MSVC)
+    set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES
+      OUTPUT_NAME ${PNG_LIB_NAME}
+      CLEAN_DIRECT_OUTPUT 1)
+  endif()
+endif()

 # If CMake > 2.4.x, we set a variable used below to export
 # targets to an export file.
@@ -723,14 +298,14 @@ if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
  if(PNG_SHARED)
    # Create a symlink for libpng.dll.a => libpng16.dll.a on Cygwin
    if(CYGWIN OR MINGW)
-       get_target_property(BUILD_TARGET_LOCATION png LOCATION_${CMAKE_BUILD_TYPE})
+       get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
       CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_IMPORT_LIBRARY_SUFFIX})
       install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX}
         DESTINATION ${CMAKE_INSTALL_LIBDIR})
    endif(CYGWIN OR MINGW)

    if(NOT WIN32)
-      get_target_property(BUILD_TARGET_LOCATION png LOCATION_${CMAKE_BUILD_TYPE})
+      get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
      CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_SHARED_LIBRARY_SUFFIX})
      install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_SHARED_LIBRARY_SUFFIX}
         DESTINATION ${CMAKE_INSTALL_LIBDIR})
@@ -739,7 +314,7 @@ if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )

  if(PNG_STATIC)
    if(NOT WIN32 OR CYGWIN OR MINGW)
-      get_target_property(BUILD_TARGET_LOCATION png_static LOCATION_${CMAKE_BUILD_TYPE})
+      get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME_STATIC} LOCATION_${CMAKE_BUILD_TYPE})
      CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_STATIC_LIBRARY_SUFFIX})
      install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_STATIC_LIBRARY_SUFFIX}
         DESTINATION ${CMAKE_INSTALL_LIBDIR})
@@ -759,11 +334,6 @@ if(NOT SKIP_INSTALL_EXECUTABLES AND NOT SKIP_INSTALL_ALL )
  endif(NOT WIN32 OR CYGWIN OR MINGW)
 endif()

-if(NOT SKIP_INSTALL_PROGRAMS AND NOT SKIP_INSTALL_ALL )
-  install(TARGETS ${PNG_BIN_TARGETS}
-      RUNTIME DESTINATION bin)
-endif()
-
 if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
  # Install man pages
  if(NOT PNG_MAN_DIR)
--- a/4
+++ b/4
@@ -47,9 +47,7 @@ If configure does not work on your system, or if you have a need to
 change configure.ac or Makefile.am, and you have a reasonably
 up-to-date set of tools, running ./autogen.sh in a git clone before
 running ./configure may fix the problem.  To be really sure that you
-aren't using any of the included pre-built scripts, especially if you
-are building from a tar distribution instead of a git distribution,
-do this:
+aren't using any of the included pre-built scripts, you can do this:

    ./configure --enable-maintainer-mode
    make maintainer-clean
--- a/32
+++ b/32
@@ -10,7 +10,7 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.0.7, July 1, 2000 through 1.6.22beta06, May 5, 2016 are
+libpng versions 1.0.7, July 1, 2000, through 1.6.21, January 15, 2016, are
 Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
@@ -32,10 +32,6 @@ and with the following additions to the disclaimer:
   risk of satisfactory quality, performance, accuracy, and effort is with
   the user.

-Some files in the "contrib" directory and some configure-generated
-files that are distributed with libpng have other copyright owners and
-are released under other open source licenses.
-
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 libpng-0.96, and are distributed according to the same disclaimer and
@@ -59,9 +55,6 @@ Contributing Authors:
   Greg Roelofs
   Tom Tanner

-Some files in the "scripts" directory have other copyright owners
-but are released under this license.
-
 libpng versions 0.5, May 1995, through 0.88, January 1996, are
 Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.

@@ -102,29 +95,18 @@ appreciated.

 END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.

-TRADEMARK:
+A "png_get_copyright" function is available, for convenient use in "about"
+boxes and the like:

-The name "libpng" has not been registered by the Copyright owner
-as a trademark in any jurisdiction.  However, because libpng has
-been distributed and maintained world-wide, continually since 1995,
-the Copyright owner claims "common-law trademark protection" in any
-jurisdiction where common-law trademark is recognized.
+   printf("%s", png_get_copyright(NULL));

-OSI CERTIFICATION:
+Also, the PNG logo (in PNG format, of course) is supplied in the
+files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).

 Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
 a certification mark of the Open Source Initiative. OSI has not addressed
 the additional disclaimers inserted at version 1.0.7.

-EXPORT CONTROL:
-
-The Copyright owner believes that the Export Control Classification
-Number (ECCN) for libpng is EAR99, which means not subject to export
-controls or International Traffic in Arms Regulations (ITAR) because
-it is open source, publicly available software, that does not contain
-any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
-734.7(b).
-
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-May 5, 2016
+January 15, 2016
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,18 +1,13 @@
-# Makefile.am, the source file for Makefile.in (and hence Makefile), is
+# Makefile.am:
+#   Source file for Makefile.in (and hence Makefile)
 #
-# Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.22 [(PENDING RELEASE)]
-#
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h

 PNGLIB_BASENAME= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@

 ACLOCAL_AMFLAGS = -I scripts

 # test programs - run on make check, make distcheck
-check_PROGRAMS= pngtest pngunknown pngstest pngvalid pngimage timepng
+check_PROGRAMS= pngtest pngunknown pngstest pngvalid pngimage

 # Utilities - installed
 bin_PROGRAMS= pngfix png-fix-itxt
@@ -42,9 +37,6 @@ pngunknown_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 pngimage_SOURCES = contrib/libtests/pngimage.c
 pngimage_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la

-timepng_SOURCES = contrib/libtests/timepng.c
-timepng_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
-
 pngfix_SOURCES = contrib/tools/pngfix.c
 pngfix_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la

--- a/2
+++ b/2
@@ -1,4 +1,4 @@
-README for libpng version 1.6.22beta06 - May 5, 2016 (shared library 16.0)
+README for libpng version 1.6.21 - January 15, 2016 (shared library 16.0)
 See the note about version numbers near the top of png.h

 See INSTALL for instructions on how to install libpng.
--- a/arm/arm_init.c
+++ b/arm/arm_init.c
@@ -1,9 +1,9 @@

 /* arm_init.c - NEON optimised filter functions
 *
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
+ * Copyright (c) 2014 Glenn Randers-Pehrson
 * Written by Mans Rullgard, 2011.
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.16 [December 22, 2014]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -66,7 +66,6 @@ png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
    * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,
    * as documented in png.h
    */
-   png_debug(1, "in png_init_filter_functions_neon");
 #ifdef PNG_ARM_NEON_API_SUPPORTED
   switch ((pp->options >> PNG_ARM_NEON) & 3)
   {
--- a/arm/filter_neon_intrinsics.c
+++ b/arm/filter_neon_intrinsics.c
@@ -1,11 +1,11 @@

 /* filter_neon_intrinsics.c - NEON optimised filter functions
 *
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
+ * Copyright (c) 2014 Glenn Randers-Pehrson
 * Written by James Yu <james.yu at linaro.org>, October 2013.
 * Based on filter_neon.S, written by Mans Rullgard, 2011.
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.16 [December 22, 2014]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -47,8 +47,6 @@ png_read_filter_row_up_neon(png_row_infop row_info, png_bytep row,
   png_bytep rp_stop = row + row_info->rowbytes;
   png_const_bytep pp = prev_row;

-   png_debug(1, "in png_read_filter_row_up_neon");
-
   for (; rp < rp_stop; rp += 16, pp += 16)
   {
      uint8x16_t qrp, qpp;
@@ -74,8 +72,6 @@ png_read_filter_row_sub3_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_sub3_neon");
-
   for (; rp < rp_stop;)
   {
      uint8x8_t vtmp1, vtmp2;
@@ -117,8 +113,6 @@ png_read_filter_row_sub4_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_sub4_neon");
-
   for (; rp < rp_stop; rp += 16)
   {
      uint32x2x4_t vtmp = vld4_u32(png_ptr(uint32_t,rp));
@@ -154,8 +148,6 @@ png_read_filter_row_avg3_neon(png_row_infop row_info, png_bytep row,
   vrpt = png_ptr(uint8x8x2_t,&vtmp);
   vrp = *vrpt;

-   png_debug(1, "in png_read_filter_row_avg3_neon");
-
   for (; rp < rp_stop; pp += 12)
   {
      uint8x8_t vtmp1, vtmp2, vtmp3;
@@ -215,8 +207,6 @@ png_read_filter_row_avg4_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_avg4_neon");
-
   for (; rp < rp_stop; rp += 16, pp += 16)
   {
      uint32x2x4_t vtmp;
@@ -290,8 +280,6 @@ png_read_filter_row_paeth3_neon(png_row_infop row_info, png_bytep row,
   vrpt = png_ptr(uint8x8x2_t,&vtmp);
   vrp = *vrpt;

-   png_debug(1, "in png_read_filter_row_paeth3_neon");
-
   for (; rp < rp_stop; pp += 12)
   {
      uint8x8x2_t *vppt;
@@ -351,8 +339,6 @@ png_read_filter_row_paeth4_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_paeth4_neon");
-
   for (; rp < rp_stop; rp += 16, pp += 16)
   {
      uint32x2x4_t vtmp;
--- a/configure.ac
+++ b/configure.ac
@@ -1,12 +1,5 @@
 # configure.ac

-# Copyright (c) 2004-2015 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.22 [(PENDING RELEASE)]
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
 dnl Process this file with autoconf to produce a configure script.
 dnl
 dnl Minor upgrades (compatible ABI): increment the package version
@@ -25,7 +18,7 @@ AC_PREREQ([2.68])

 dnl Version number stuff here:

-AC_INIT([libpng],[1.6.22beta06],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.21],[png-mng-implement@lists.sourceforge.net])
 AC_CONFIG_MACRO_DIR([scripts])

 # libpng does not follow GNU file name conventions (hence 'foreign')
@@ -46,10 +39,10 @@ dnl automake, so the following is not necessary (and is not defined anyway):
 dnl AM_PREREQ([1.11.2])
 dnl stop configure from automagically running automake

-PNGLIB_VERSION=1.6.22beta06
+PNGLIB_VERSION=1.6.21
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=22
+PNGLIB_RELEASE=21

 dnl End of version number stuff

@@ -114,25 +107,6 @@ AC_ARG_ENABLE(werror,
      CFLAGS="$sav_CFLAGS"
    fi],)

-# For GCC 5 the default mode for C is -std=gnu11 instead of -std=gnu89
-# In pngpriv.h we request just the POSIX 1003.1 and C89 APIs by defining _POSIX_SOURCE to 1
-# This is incompatible with the new default mode, so we test for that and force the 
-# "-std=c89" compiler option:
-AC_MSG_CHECKING([if we need to force back C standard to C89])
-AC_COMPILE_IFELSE(
-   [AC_LANG_PROGRAM([
-      [#define _POSIX_SOURCE 1]
-      [#include <stdio.h>]
-   ])],
-   AC_MSG_RESULT(no),[
-      if test "x$GCC" != "xyes"; then
-         AC_MSG_ERROR(
-            [Forcing back to C89 is required but the flags are only known for GCC])
-      fi
-   AC_MSG_RESULT(yes)
-   CFLAGS="$CFLAGS -std=c89"
-])
-
 # Checks for header files.
 AC_HEADER_STDC

--- a/contrib/intel/INSTALL
+++ b/contrib/intel/INSTALL
@@ -1,176 +0,0 @@
-Enabling SSE support
-
-Copyright (c) 2016 Google, Inc.
-Written by Mike Klein, Matt Sarett
-
-This INSTALL file written by Glenn Randers-Pehrson, 2016.
-
-If you have moved intel_init.c and filter_sse2_intrinsics.c to a different
-directory, be sure to update the '#include "../../pngpriv.h"' line in both
-files if necessary to point to the correct relative location of pngpriv.h
-with respect to the new location of those files.
-
-To enable SSE support in libpng, follow the instructions in I, II, or III,
-below:
-
-I. Using patched "configure" scripts:
-
-First, apply intel_sse.patch in your build directory.
-
-   patch -i contrib/intel/intel_sse.patch -p1
-
-Then, if you are not building in a new GIT clone, e.g., in a tar
-distribution, remove any existing pre-built configure scripts:
-
-   ./configure --enable-maintainer-mode
-   make maintainer-clean
-   ./autogen.sh --maintainer --clean
-
-Finally, configure libpng with -DPNG_INTEL_SSE in CPPFLAGS:
-
-   ./autogen.sh --maintainer
-   CPPFLAGS="-DPNG_INTEL_SSE" ./configure [options]
-   make CPPFLAGS="-DPNG_INTEL_SSE" [options]
-   make
-
-II. Using a custom makefile:
-
-If you are using a custom makefile makefile, you will have to update it
-manually to include contrib/intel/*.o in the dependencies, and to define
-PNG_INTEL_SSE.
-
-III. Using manually updated "configure" scripts:
-
-If you prefer, manually edit pngpriv.h, configure.ac, and Makefile.am,
-following the instructions below, then follow the instructions in
-section II of INSTALL in the main libpng directory, then configure libpng
-with -DPNG_INTEL_SSE in CPPFLAGS.
-
-1. Insert the following lines above the copyright line near the top of
-configure.ac:
-
-----------------cut----------------
-# Copyright (c) 2016 Google, Inc.
-# Written by Mike Klein and Matt Sarett
-# Derived from the ARM supporting code in libpng/configure.ac, which was
-----------------cut----------------
-
-2. Add the following code to configure.ac under HOST SPECIFIC OPTIONS
-directly beneath the section for ARM:
-
-----------------cut----------------
-# INTEL
-# =====
-#
-# INTEL SSE (SIMD) support.
-
-AC_ARG_ENABLE([intel-sse],
-   AS_HELP_STRING([[[--enable-intel-sse]]],
-      [Enable Intel SSE optimizations: =no/off, yes/on:]
-      [no/off: disable the optimizations;]
-      [yes/on: enable the optimizations.]
-      [If not specified: determined by the compiler.]),
-   [case "$enableval" in
-      no|off)
-         # disable the default enabling:
-         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
-                   [Disable Intel SSE optimizations])
-         # Prevent inclusion of the assembler files below:
-         enable_intel_sse=no;;
-      yes|on)
-         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
-                   [Enable Intel SSE optimizations]);;
-      *)
-         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
-   esac])
-
-# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
-# or where Intel optimizations were explicitly requested (this allows a
-# fallback if a future host CPU does not match 'x86*')
-AM_CONDITIONAL([PNG_INTEL_SSE],
-   [test "$enable_intel_sse" != 'no' &&
-    case "$host_cpu" in
-      i?86|x86_64) :;;
-      *)    test "$enable_intel_sse" != '';;
-    esac])
-----------------cut----------------
-
-3. Insert the following lines above the copyright line near the top of
-Makefile.am:
-
-----------------cut----------------
-# Copyright (c) 2016 Google, Inc.
-# Written by Mike Klein and Matt Sarett
-# Derived from the ARM supporting code in libpng/configure.ac, which was
-----------------cut----------------
-
-4. Add the following code to Makefile.am under HOST SPECIFIC OPTIONS
-directly beneath the "if PNG_ARM_NEON ... endif" statement:
-
-----------------cut----------------
-if PNG_INTEL_SSE
-libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
-    contrib/intel/filter_sse2_intrinsics.c
-endif
-----------------cut----------------
-
-5. Add the following lines to pngpriv.h, following the PNG_ARM_NEON_OPT
-code:
-
-----------------cut----------------
-#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
-
-----------------cut----------------
-
-5. Add the following lines to pngpriv.h, following the prototype for
-png_read_filter_row_paeth4_neon:
-
-----------------cut----------------
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-
-----------------cut----------------
--- a/contrib/intel/filter_sse2_intrinsics.c
+++ b/contrib/intel/filter_sse2_intrinsics.c
@@ -1,379 +0,0 @@
-
-/* filter_sse2_intrinsics.c - SSE2 optimized filter functions
- *
- * Copyright (c) 2016 Google, Inc.
- * Written by Mike Klein and Matt Sarett
- * Derived from arm/filter_neon_intrinsics.c, which was
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
- *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-
-#include "../../pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-
-#if PNG_INTEL_SSE_IMPLEMENTATION > 0
-
-#include <immintrin.h>
-
-/* Functions in this file look at most 3 pixels (a,b,c) to predict the 4th (d).
- * They're positioned like this:
- *    prev:  c b
- *    row:   a d
- * The Sub filter predicts d=a, Avg d=(a+b)/2, and Paeth predicts d to be
- * whichever of a, b, or c is closest to p=a+b-c.
- */
-
-static __m128i load4(const void* p) {
-   return _mm_cvtsi32_si128(*(const int*)p);
-}
-
-static void store4(void* p, __m128i v) {
-   *(int*)p = _mm_cvtsi128_si32(v);
-}
-
-static __m128i load3(const void* p) {
-   /* We'll load 2 bytes, then 1 byte,
-    * then mask them together, and finally load into SSE.
-    */
-   const png_uint_16* p01 = p;
-   const png_byte*    p2  = (const png_byte*)(p01+1);
-
-   png_uint_32 v012 = (png_uint_32)(*p01)
-                    | (png_uint_32)(*p2) << 16;
-   return load4(&v012);
-}
-
-static void store3(void* p, __m128i v) {
-   /* We'll pull from SSE as a 32-bit int, then write
-    * its bottom two bytes, then its third byte.
-    */
-   png_uint_32 v012;
-   store4(&v012, v);
-
-   png_uint_16* p01 = p;
-   png_byte*    p2  = (png_byte*)(p01+1);
-   *p01 = v012;
-   *p2  = v012 >> 16;
-}
-
-void png_read_filter_row_sub3_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Sub filter predicts each pixel as the previous pixel, a.
-    * There is no pixel to the left of the first pixel.  It's encoded directly.
-    * That works with our main loop if we just say that left pixel was zero.
-    */
-   png_debug(1, "in png_read_filter_row_sub3_sse2");
-   __m128i a, d = _mm_setzero_si128();
-
-   int rb = row_info->rowbytes;
-   while (rb >= 4) {
-      a = d; d = load4(row);
-      d = _mm_add_epi8(d, a);
-      store3(row, d);
-
-      row += 3;
-      rb  -= 3;
-   }
-   if (rb > 0) {
-      a = d; d = load3(row);
-      d = _mm_add_epi8(d, a);
-      store3(row, d);
-
-      row += 3;
-      rb  -= 3;
-   }
-}
-
-void png_read_filter_row_sub4_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Sub filter predicts each pixel as the previous pixel, a.
-    * There is no pixel to the left of the first pixel.  It's encoded directly.
-    * That works with our main loop if we just say that left pixel was zero.
-    */
-   png_debug(1, "in png_read_filter_row_sub4_sse2");
-   __m128i a, d = _mm_setzero_si128();
-
-   int rb = row_info->rowbytes;
-   while (rb > 0) {
-      a = d; d = load4(row);
-      d = _mm_add_epi8(d, a);
-      store4(row, d);
-
-      row += 4;
-      rb  -= 4;
-   }
-}
-
-void png_read_filter_row_avg3_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Avg filter predicts each pixel as the (truncated) average of a and b.
-    * There's no pixel to the left of the first pixel.  Luckily, it's
-    * predicted to be half of the pixel above it.  So again, this works
-    * perfectly with our loop if we make sure a starts at zero.
-    */
-   png_debug(1, "in png_read_filter_row_avg3_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i    b;
-   __m128i a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb >= 4) {
-             b = load4(prev);
-      a = d; d = load4(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      __m128i avg = _mm_avg_epu8(a,b);
-      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
-      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
-                                            _mm_set1_epi8(1)));
-      d = _mm_add_epi8(d, avg);
-      store3(row, d);
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-   if (rb > 0) {
-             b = load3(prev);
-      a = d; d = load3(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      __m128i avg = _mm_avg_epu8(a,b);
-      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
-      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
-                                            _mm_set1_epi8(1)));
-
-      d = _mm_add_epi8(d, avg);
-      store3(row, d);
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-}
-
-void png_read_filter_row_avg4_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Avg filter predicts each pixel as the (truncated) average of a and b.
-    * There's no pixel to the left of the first pixel.  Luckily, it's
-    * predicted to be half of the pixel above it.  So again, this works
-    * perfectly with our loop if we make sure a starts at zero.
-    */
-   png_debug(1, "in png_read_filter_row_avg4_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i    b;
-   __m128i a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb > 0) {
-             b = load4(prev);
-      a = d; d = load4(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      __m128i avg = _mm_avg_epu8(a,b);
-      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
-      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
-                                            _mm_set1_epi8(1)));
-
-      d = _mm_add_epi8(d, avg);
-      store4(row, d);
-
-      prev += 4;
-      row  += 4;
-      rb   -= 4;
-   }
-}
-
-/* Returns |x| for 16-bit lanes. */
-static __m128i abs_i16(__m128i x) {
-#if PNG_INTEL_SSE_IMPLEMENTATION >= 2
-   return _mm_abs_epi16(x);
-#else
-   /* Read this all as, return x<0 ? -x : x.
-   * To negate two's complement, you flip all the bits then add 1.
-    */
-   __m128i is_negative = _mm_cmplt_epi16(x, _mm_setzero_si128());
-
-   /* Flip negative lanes. */
-   x = _mm_xor_si128(x, is_negative);
-
-   /* +1 to negative lanes, else +0. */
-   x = _mm_add_epi16(x, _mm_srli_epi16(is_negative, 15));
-   return x;
-#endif
-}
-
-/* Bytewise c ? t : e. */
-static __m128i if_then_else(__m128i c, __m128i t, __m128i e) {
-#if PNG_INTEL_SSE_IMPLEMENTATION >= 3
-   return _mm_blendv_epi8(e,t,c);
-#else
-   return _mm_or_si128(_mm_and_si128(c, t), _mm_andnot_si128(c, e));
-#endif
-}
-
-void png_read_filter_row_paeth3_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* Paeth tries to predict pixel d using the pixel to the left of it, a,
-    * and two pixels from the previous row, b and c:
-    *   prev: c b
-    *   row:  a d
-    * The Paeth function predicts d to be whichever of a, b, or c is nearest to
-    * p=a+b-c.
-    *
-    * The first pixel has no left context, and so uses an Up filter, p = b.
-    * This works naturally with our main loop's p = a+b-c if we force a and c
-    * to zero.
-    * Here we zero b and d, which become c and a respectively at the start of
-    * the loop.
-    */
-   png_debug(1, "in png_read_filter_row_paeth3_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i c, b = zero,
-           a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb >= 4) {
-      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
-       * intermediates.
-       */
-      c = b; b = _mm_unpacklo_epi8(load4(prev), zero);
-      a = d; d = _mm_unpacklo_epi8(load4(row ), zero);
-
-      /* (p-a) == (a+b-c - a) == (b-c) */
-      __m128i pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      __m128i pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      __m128i pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
-                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
-                                                                     c));
-
-      /* Note `_epi8`: we need addition to wrap modulo 255. */
-      d = _mm_add_epi8(d, nearest);
-      store3(row, _mm_packus_epi16(d,d));
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-   if (rb > 0) {
-      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
-       * intermediates.
-       */
-      c = b; b = _mm_unpacklo_epi8(load3(prev), zero);
-      a = d; d = _mm_unpacklo_epi8(load3(row ), zero);
-
-      /* (p-a) == (a+b-c - a) == (b-c) */
-      __m128i pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      __m128i pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      __m128i pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
-                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
-                                                                     c));
-
-      /* Note `_epi8`: we need addition to wrap modulo 255. */
-      d = _mm_add_epi8(d, nearest);
-      store3(row, _mm_packus_epi16(d,d));
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-}
-
-void png_read_filter_row_paeth4_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* Paeth tries to predict pixel d using the pixel to the left of it, a,
-    * and two pixels from the previous row, b and c:
-    *   prev: c b
-    *   row:  a d
-    * The Paeth function predicts d to be whichever of a, b, or c is nearest to
-    * p=a+b-c.
-    *
-    * The first pixel has no left context, and so uses an Up filter, p = b.
-    * This works naturally with our main loop's p = a+b-c if we force a and c
-    * to zero.
-    * Here we zero b and d, which become c and a respectively at the start of
-    * the loop.
-    */
-   png_debug(1, "in png_read_filter_row_paeth4_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i c, b = zero,
-           a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb > 0) {
-      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
-       * intermediates.
-       */
-      c = b; b = _mm_unpacklo_epi8(load4(prev), zero);
-      a = d; d = _mm_unpacklo_epi8(load4(row ), zero);
-
-      /* (p-a) == (a+b-c - a) == (b-c) */
-      __m128i pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      __m128i pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      __m128i pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
-                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
-                                                                     c));
-
-      /* Note `_epi8`: we need addition to wrap modulo 255. */
-      d = _mm_add_epi8(d, nearest);
-      store4(row, _mm_packus_epi16(d,d));
-
-      prev += 4;
-      row  += 4;
-      rb   -= 4;
-   }
-}
-
-#endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
-#endif /* READ */
--- a/contrib/intel/intel_init.c
+++ b/contrib/intel/intel_init.c
@@ -1,54 +0,0 @@
-
-/* intel_init.c - SSE2 optimized filter functions
- *
- * Copyright (c) 2016 Google, Inc.
- * Written by Mike Klein and Matt Sarett
- * Derived from arm/arm_init.c, which was
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
- *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-
-#include "../../pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-#if PNG_INTEL_SSE_IMPLEMENTATION > 0
-
-void
-png_init_filter_functions_sse2(png_structp pp, unsigned int bpp)
-{
-   /* The techniques used to implement each of these filters in SSE operate on
-    * one pixel at a time.
-    * So they generally speed up 3bpp images about 3x, 4bpp images about 4x.
-    * They can scale up to 6 and 8 bpp images and down to 2 bpp images,
-    * but they'd not likely have any benefit for 1bpp images.
-    * Most of these can be implemented using only MMX and 64-bit registers,
-    * but they end up a bit slower than using the equally-ubiquitous SSE2.
-   */
-   png_debug(1, "in png_init_filter_functions_sse2");
-   if (bpp == 3)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
-         png_read_filter_row_paeth3_sse2;
-   }
-   else if (bpp == 4)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
-          png_read_filter_row_paeth4_sse2;
-   }
-
-   /* No need optimize PNG_FILTER_VALUE_UP.  The compiler should
-    * autovectorize.
-    */
-}
-
-#endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
-#endif /* PNG_READ_SUPPORTED */
--- a/contrib/intel/intel_sse.patch
+++ b/contrib/intel/intel_sse.patch
@@ -1,192 +0,0 @@
-diff --git a/configure.ac b/configure.ac
--- a/configure.ac	2016-04-27 22:33:47.805069558 -0500
-+++ b/configure.ac	2016-04-27 22:33:47.829012469 -0500
-@@ -1,10 +1,13 @@
- # configure.ac
- 
-+# Copyright (c) 2016 Google, Inc.
-+# Written by Mike Klein and Matt Sarett
-+# Derived from the ARM supporting code in libpng/configure.ac, which was
- # Copyright (c) 2004-2015 Glenn Randers-Pehrson
- # Last changed in libpng 1.6.22 [(PENDING RELEASE)]
- 
- # This code is released under the libpng license.
- # For conditions of distribution and use, see the disclaimer
- # and license in png.h
- 
- dnl Process this file with autoconf to produce a configure script.
-@@ -335,16 +338,50 @@ AC_ARG_ENABLE([arm-neon],
- 
- AM_CONDITIONAL([PNG_ARM_NEON],
-    [test "$enable_arm_neon" != 'no' &&
-     case "$host_cpu" in
-       arm*|aarch64*) :;;
-       *)    test "$enable_arm_neon" != '';;
-     esac])
- 
-+# INTEL
-+# =====
-+#
-+# INTEL SSE (SIMD) support.
-+
-+AC_ARG_ENABLE([intel-sse],
-+   AS_HELP_STRING([[[--enable-intel-sse]]],
-+      [Enable Intel SSE optimizations: =no/off, yes/on:]
-+      [no/off: disable the optimizations;]
-+      [yes/on: enable the optimizations.]
-+      [If not specified: determined by the compiler.]),
-+   [case "$enableval" in
-+      no|off)
-+         # disable the default enabling:
-+         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
-+                   [Disable Intel SSE optimizations])
-+         # Prevent inclusion of the assembler files below:
-+         enable_intel_sse=no;;
-+      yes|on)
-+         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
-+                   [Enable Intel SSE optimizations]);;
-+      *)
-+         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
-+   esac])
-+
-+# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
-+# or where Intel optimizations were explicitly requested (this allows a
-+# fallback if a future host CPU does not match 'x86*')
-+AM_CONDITIONAL([PNG_INTEL_SSE],
-+   [test "$enable_intel_sse" != 'no' &&
-+    case "$host_cpu" in
-+      i?86|x86_64) :;;
-+      *)    test "$enable_intel_sse" != '';;
-+    esac])
- AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
- 
- # Config files, substituting as above
- AC_CONFIG_FILES([Makefile libpng.pc:libpng.pc.in])
- AC_CONFIG_FILES([libpng-config:libpng-config.in],
-    [chmod +x libpng-config])
- 
- AC_OUTPUT
-diff --git a/Makefile.am b/Makefile.am
--- a/Makefile.am	2016-04-27 22:33:47.809928404 -0500
-+++ b/Makefile.am	2016-04-27 22:33:47.832941146 -0500
-@@ -1,10 +1,13 @@
- # Makefile.am, the source file for Makefile.in (and hence Makefile), is
- #
-+# Copyright (c) 2016 Google, Inc.
-+# Written by Mike Klein and Matt Sarett
-+# Derived from the ARM supporting code in libpng/configure.ac, which was
- # Copyright (c) 2004-2016 Glenn Randers-Pehrson
- # Last changed in libpng 1.6.22 [(PENDING RELEASE)]
- #
- # This code is released under the libpng license.
- # For conditions of distribution and use, see the disclaimer
- # and license in png.h
- 
- PNGLIB_BASENAME= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
-@@ -86,16 +89,20 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SO
- 	pngset.c pngtrans.c pngwio.c pngwrite.c pngwtran.c pngwutil.c\
- 	png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h pngusr.dfa
- 
- if PNG_ARM_NEON
- libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
- 	arm/filter_neon.S arm/filter_neon_intrinsics.c
- endif
- 
-+if PNG_INTEL_SSE
-+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
-+    contrib/intel/filter_sse2_intrinsics.c
-+endif
- nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
- 
- libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
- 	-version-number @PNGLIB_MAJOR@@PNGLIB_MINOR@:@PNGLIB_RELEASE@:0
- 
- if HAVE_LD_VERSION_SCRIPT
- #   Versioned symbols and restricted exports
- if HAVE_SOLARIS_LD
-diff --git a/pngpriv.h b/pngpriv.h
--- a/pngpriv.h	2016-04-27 22:33:47.800157005 -0500
-+++ b/pngpriv.h	2016-04-27 22:33:47.838191194 -0500
-@@ -177,16 +177,52 @@
- #  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_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
-+
- /* 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.
-  */
-@@ -1184,16 +1220,29 @@ PNG_INTERNAL_FUNCTION(void,png_read_filt
-     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);
- 
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+
- /* 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
--- a/contrib/libtests/pngimage.c
+++ b/contrib/libtests/pngimage.c
@@ -1,8 +1,8 @@
 /* pngimage.c
 *
- * Copyright (c) 2015,2016 John Cunningham Bowler
+ * Copyright (c) 2015 John Cunningham Bowler
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.20 [December 3, 2015]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -36,15 +36,6 @@
 #  include <setjmp.h> /* because png.h did *not* include this */
 #endif

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
 #if defined(PNG_INFO_IMAGE_SUPPORTED) && defined(PNG_SEQUENTIAL_READ_SUPPORTED)\
    && (defined(PNG_READ_PNG_SUPPORTED) || PNG_LIBPNG_VER < 10700)
 /* If a transform is valid on both read and write this implies that if the
@@ -1691,6 +1682,6 @@ int
 main(void)
 {
   fprintf(stderr, "pngimage: no support for png_read/write_image\n");
-   return SKIP;
+   return 77;
 }
 #endif
--- a/contrib/libtests/pngstest.c
+++ b/contrib/libtests/pngstest.c
@@ -1,9 +1,9 @@
 /*-
 * pngstest.c
 *
- * Copyright (c) 2013-2016 John Cunningham Bowler
+ * Copyright (c) 2013-2015 John Cunningham Bowler
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -26,15 +26,6 @@
 #  include <config.h>
 #endif

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
 /* Define the following to use this test against your installed libpng, rather
 * than the one being built here:
 */
@@ -108,18 +99,10 @@ make_random_bytes(png_uint_32* seed, void* pv, size_t size)
   seed[1] = u1;
 }

-static png_uint_32 color_seed[2];
-
-static void
-reseed(void)
-{
-   color_seed[0] = 0x12345678U;
-   color_seed[1] = 0x9abcdefU;
-}
-
 static void
 random_color(png_colorp color)
 {
+   static png_uint_32 color_seed[2] = { 0x12345678, 0x9abcdef };
   make_random_bytes(color_seed, color, sizeof *color);
 }

@@ -324,7 +307,7 @@ compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
 }
 #endif /* unused */

-#define USE_FILE 1       /* else memory */
+#define READ_FILE 1      /* else memory */
 #define USE_STDIO 2      /* else use file name */
 #define STRICT 4         /* fail on warnings too */
 #define VERBOSE 8
@@ -333,19 +316,16 @@ compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
 #define ACCUMULATE 64
 #define FAST_WRITE 128
 #define sRGB_16BIT 256
-#define NO_RESEED  512   /* do not reseed on each new file */
-#define GBG_ERROR 1024   /* do not ignore the gamma+background_rgb_to_gray
-                          * libpng warning. */

 static void
 print_opts(png_uint_32 opts)
 {
-   if (opts & USE_FILE)
+   if (opts & READ_FILE)
      printf(" --file");
   if (opts & USE_STDIO)
      printf(" --stdio");
-   if (!(opts & STRICT))
-      printf(" --nostrict");
+   if (opts & STRICT)
+      printf(" --strict");
   if (opts & VERBOSE)
      printf(" --verbose");
   if (opts & KEEP_TMPFILES)
@@ -358,12 +338,6 @@ print_opts(png_uint_32 opts)
      printf(" --slow");
   if (opts & sRGB_16BIT)
      printf(" --sRGB-16bit");
-   if (opts & NO_RESEED)
-      printf(" --noreseed");
-#if PNG_LIBPNG_VER < 10700 /* else on by default */
-   if (opts & GBG_ERROR)
-      printf(" --fault-gbg-warning");
-#endif
 }

 #define FORMAT_NO_CHANGE 0x80000000 /* additional flag */
@@ -767,15 +741,8 @@ checkopaque(Image *image)
      return logerror(image, image->file_name, ": opaque not NULL", "");
   }

-   /* Separate out the gamma+background_rgb_to_gray warning because it may
-    * produce opaque component errors:
-    */
-   else if (image->image.warning_or_error != 0 &&
-            (strcmp(image->image.message,
-               "libpng does not support gamma+background+rgb_to_gray") == 0 ?
-                  (image->opts & GBG_ERROR) != 0 : (image->opts & STRICT) != 0))
-      return logerror(image, image->file_name, (image->opts & GBG_ERROR) != 0 ?
-                      " --fault-gbg-warning" : " --strict", "");
+   else if (image->image.warning_or_error != 0 && (image->opts & STRICT) != 0)
+      return logerror(image, image->file_name, " --strict", "");

   else
      return 1;
@@ -3041,14 +3008,14 @@ read_file(Image *image, png_uint_32 format, png_const_colorp background)
 static int
 read_one_file(Image *image)
 {
-   if (!(image->opts & USE_FILE) || (image->opts & USE_STDIO))
+   if (!(image->opts & READ_FILE) || (image->opts & USE_STDIO))
   {
      /* memory or stdio. */
      FILE *f = fopen(image->file_name, "rb");

      if (f != NULL)
      {
-         if (image->opts & USE_FILE)
+         if (image->opts & READ_FILE)
            image->input_file = f;

         else /* memory */
@@ -3129,8 +3096,7 @@ write_one_file(Image *output, Image *image, int convert_to_8bit)

   if (image->opts & USE_STDIO)
   {
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
-#ifndef __COVERITY__
+#ifndef PNG_USE_MKSTEMP
      FILE *f = tmpfile();
 #else
      /* Experimental. Coverity says tmpfile() is insecure because it
@@ -3192,14 +3158,10 @@ write_one_file(Image *output, Image *image, int convert_to_8bit)

      else
         return logerror(image, "tmpfile", ": open: ", strerror(errno));
-#else /* SIMPLIFIED_WRITE_STDIO */
-      return logerror(image, "tmpfile", ": open: unsupported", "");
-#endif /* SIMPLIFIED_WRITE_STDIO */
   }

-   else if (image->opts & USE_FILE)
+   else
   {
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
      static int counter = 0;
      char name[32];

@@ -3219,51 +3181,6 @@ write_one_file(Image *output, Image *image, int convert_to_8bit)

      else
         return logerror(image, name, ": write failed", "");
-#else /* SIMPLIFIED_WRITE_STDIO */
-      return logerror(image, "stdio", ": open: unsupported", "");
-#endif /* SIMPLIFIED_WRITE_STDIO */
-   }
-
-   else /* use memory */
-   {
-      png_alloc_size_t size;
-
-      if (png_image_write_get_memory_size(image->image, size, convert_to_8bit,
-               image->buffer+16, (png_int_32)image->stride, image->colormap))
-      {
-         /* This is non-fatal but ignoring it was causing serious problems in
-          * the macro to be ignored:
-          */
-         if (size > PNG_IMAGE_PNG_SIZE_MAX(image->image))
-            return logerror(image, "memory", ": PNG_IMAGE_SIZE_MAX wrong", "");
-
-         initimage(output, image->opts, "memory", image->stride_extra);
-         output->input_memory = malloc(size);
-
-         if (output->input_memory != NULL)
-         {
-            output->input_memory_size = size;
-
-            if (png_image_write_to_memory(&image->image, output->input_memory,
-                  &output->input_memory_size, convert_to_8bit, image->buffer+16,
-                  (png_int_32)image->stride, image->colormap))
-            {
-               /* This is also non-fatal but it safes safer to error out anyway:
-                */
-               if (size != output->input_memory_size)
-                  return logerror(image, "memory", ": memory size wrong", "");
-            }
-
-            else
-               return logerror(image, "memory", ": write failed", "");
-         }
-
-         else
-            return logerror(image, "memory", ": out of memory", "");
-      }
-
-      else
-         return logerror(image, "memory", ": get size:", "");
   }

   /* 'output' has an initialized temporary image, read this back in and compare
@@ -3439,8 +3356,6 @@ test_one_file(const char *file_name, format_list *formats, png_uint_32 opts,
   int result;
   Image image;

-   if (!(opts & NO_RESEED))
-      reseed(); /* ensure that the random numbers don't depend on file order */
   newimage(&image);
   initimage(&image, opts, file_name, stride_extra);
   result = read_one_file(&image);
@@ -3478,7 +3393,7 @@ test_one_file(const char *file_name, format_list *formats, png_uint_32 opts,
 int
 main(int argc, char **argv)
 {
-   png_uint_32 opts = FAST_WRITE | STRICT;
+   png_uint_32 opts = FAST_WRITE;
   format_list formats;
   const char *touch = NULL;
   int log_pass = 0;
@@ -3487,17 +3402,11 @@ main(int argc, char **argv)
   int retval = 0;
   int c;

-#if PNG_LIBPNG_VER >= 10700
-      /* This error should not exist in 1.7 or later: */
-      opts |= GBG_ERROR;
-#endif
-
   init_sRGB_to_d();
 #if 0
   init_error_via_linear();
 #endif
   format_init(&formats);
-   reseed(); /* initialize random number seeds */

   for (c=1; c<argc; ++c)
   {
@@ -3512,17 +3421,17 @@ main(int argc, char **argv)
      }
      else if (strcmp(arg, "--file") == 0)
 #        ifdef PNG_STDIO_SUPPORTED
-            opts |= USE_FILE;
+            opts |= READ_FILE;
 #        else
-            return SKIP; /* skipped: no support */
+            return 77; /* skipped: no support */
 #        endif
      else if (strcmp(arg, "--memory") == 0)
-         opts &= ~USE_FILE;
+         opts &= ~READ_FILE;
      else if (strcmp(arg, "--stdio") == 0)
 #        ifdef PNG_STDIO_SUPPORTED
            opts |= USE_STDIO;
 #        else
-            return SKIP; /* skipped: no support */
+            return 77; /* skipped: no support */
 #        endif
      else if (strcmp(arg, "--name") == 0)
         opts &= ~USE_STDIO;
@@ -3548,16 +3457,10 @@ main(int argc, char **argv)
         opts &= ~KEEP_GOING;
      else if (strcmp(arg, "--strict") == 0)
         opts |= STRICT;
-      else if (strcmp(arg, "--nostrict") == 0)
-         opts &= ~STRICT;
      else if (strcmp(arg, "--sRGB-16bit") == 0)
         opts |= sRGB_16BIT;
      else if (strcmp(arg, "--linear-16bit") == 0)
         opts &= ~sRGB_16BIT;
-      else if (strcmp(arg, "--noreseed") == 0)
-         opts |= NO_RESEED;
-      else if (strcmp(arg, "--fault-gbg-warning") == 0)
-         opts |= GBG_ERROR;
      else if (strcmp(arg, "--tmpfile") == 0)
      {
         if (c+1 < argc)
@@ -3814,6 +3717,6 @@ int main(void)
 {
   fprintf(stderr, "pngstest: no read support in libpng, test skipped\n");
   /* So the test is skipped: */
-   return SKIP;
+   return 77;
 }
 #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
--- a/contrib/libtests/pngunknown.c
+++ b/contrib/libtests/pngunknown.c
@@ -1,8 +1,8 @@

 /* pngunknown.c - test the read side unknown chunk handling
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
- * Copyright (c) 2015,2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.10 [March 6, 2014]
+ * Copyright (c) 2014 Glenn Randers-Pehrson
 * Written by John Cunningham Bowler
 *
 * This code is released under the libpng license.
@@ -30,21 +30,10 @@
 #  include "../../png.h"
 #endif

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
-
 /* Since this program tests the ability to change the unknown chunk handling
 * these must be defined:
 */
 #if defined(PNG_SET_UNKNOWN_CHUNKS_SUPPORTED) &&\
-   defined(PNG_STDIO_SUPPORTED) &&\
   defined(PNG_READ_SUPPORTED)

 /* One of these must be defined to allow us to find out what happened.  It is
@@ -626,7 +615,7 @@ get_unknown(display *d, png_infop info_ptr, int after_IDAT)

   return flags;
 }
-#else /* SAVE_UNKNOWN_CHUNKS */
+#else
 static png_uint_32
 get_unknown(display *d, png_infop info_ptr, int after_IDAT)
   /* Otherwise this will return the cached values set by any user callback */
@@ -645,8 +634,8 @@ get_unknown(display *d, png_infop info_ptr, int after_IDAT)
       * a check to ensure the logic is correct.
       */
 #     error No store support and no user chunk support, this will not work
-#  endif /* READ_USER_CHUNKS */
-#endif /* SAVE_UNKNOWN_CHUNKS */
+#  endif
+#endif

 static int
 check(FILE *fp, int argc, const char **argv, png_uint_32p flags/*out*/,
@@ -1012,20 +1001,6 @@ perform_one_test(FILE *fp, int argc, const char **argv,

   def = check(fp, argc, argv, flags[1], d, set_callback);

-   /* If IDAT is being handled as unknown the image read is skipped and all the
-    * IDATs after the first end up in the end info struct, so in this case add
-    * IDAT to the list of unknowns.  (Do this after 'check' above sets the
-    * chunk_info 'keep' fields.)
-    *
-    * Note that the flag setting has to be in the 'known' field to avoid
-    * triggering the consistency check below and the flag must only be set if
-    * there are multiple IDATs, so if the check above did find an unknown IDAT
-    * after IDAT.
-    */
-   if (chunk_info[0/*IDAT*/].keep != PNG_HANDLE_CHUNK_AS_DEFAULT &&
-       (flags[1][3] & PNG_INFO_IDAT) != 0)
-      flags[0][2] |= PNG_INFO_IDAT;
-
   /* Chunks should either be known or unknown, never both and this should apply
    * whether the chunk is before or after the IDAT (actually, the app can
    * probably change this by swapping the handling after the image, but this
@@ -1270,7 +1245,7 @@ main(void)
   fprintf(stderr,
      " test ignored: no support to find out about unknown chunks\n");
   /* So the test is skipped: */
-   return SKIP;
+   return 77;
 }
 #endif /* READ_USER_CHUNKS || SAVE_UNKNOWN_CHUNKS */

@@ -1281,6 +1256,6 @@ main(void)
   fprintf(stderr,
      " test ignored: no support to modify unknown chunk handling\n");
   /* So the test is skipped: */
-   return SKIP;
+   return 77;
 }
 #endif /* SET_UNKNOWN_CHUNKS && READ*/
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -1,7 +1,7 @@

 /* pngvalid.c - validate libpng by constructing then reading png files.
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.21 [January 15, 2016]
 * Copyright (c) 2014-2016 Glenn Randers-Pehrson
 * Written by John Cunningham Bowler
 *
@@ -62,10 +62,10 @@
 /* 1.6.1 added support for the configure test harness, which uses 77 to indicate
 * a skipped test, in earlier versions we need to succeed on a skipped test, so:
 */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
+#if PNG_LIBPNG_VER < 10601
 #  define SKIP 0
+#else
+#  define SKIP 77
 #endif

 /* pngvalid requires write support and one of the fixed or floating point APIs.
@@ -309,8 +309,13 @@ static void r16(png_uint_16p p16, size_t count)
   }
 }

-#define R16(this) r16(&(this), (sizeof (this))/(sizeof (png_uint_16)))
-#define R16_1(this) r16(&(this), (size_t) 1U)
+#ifdef __COVERITY__
+#  define R16(this)\
+   r16(&(this), (sizeof (this))/2U/*(sizeof (png_uint_16))*/)
+#else
+#  define R16(this)\
+   r16(&(this), (sizeof (this))/(sizeof (png_uint_16)))
+#endif

 #if defined PNG_READ_RGB_TO_GRAY_SUPPORTED ||\
    defined PNG_READ_FILLER_SUPPORTED
@@ -326,8 +331,13 @@ static void r32(png_uint_32p p32, size_t count)
   }
 }

-#define R32(this) r32(&(this), (sizeof (this))/(sizeof (png_uint_32)))
-#define R32_1(this) r32(&(this), (size_t) 1U)
+#ifdef __COVERITY__
+#  define R32(this)\
+   r32(&(this), (sizeof (this))/4U/*(sizeof (png_uint_32))*/)
+#else
+#  define R32(this)\
+   r32(&(this), (sizeof (this))/(sizeof (png_uint_32)))
+#endif

 #endif /* READ_FILLER || READ_RGB_TO_GRAY */

@@ -340,7 +350,7 @@ random_mod(unsigned int max)
 {
   png_uint_16 x;

-   R16_1(x);
+   R16(x);

   return x % max; /* 0 .. max-1 */
 }
@@ -3307,10 +3317,10 @@ init_standard_palette(png_store *ps, png_structp pp, png_infop pi, int npalette,
      for (; i<256; ++i)
         tRNS[i] = 24;

-#ifdef PNG_WRITE_tRNS_SUPPORTED
-      if (j > 0)
-         png_set_tRNS(pp, pi, tRNS, j, 0/*color*/);
-#endif
+#     ifdef PNG_WRITE_tRNS_SUPPORTED
+         if (j > 0)
+            png_set_tRNS(pp, pi, tRNS, j, 0/*color*/);
+#     endif
   }
 }

@@ -7303,7 +7313,7 @@ image_transform_png_set_rgb_to_gray_ini(const image_transform *this,
      png_uint_32 ru;
      double total;

-      R32_1(ru);
+      R32(ru);
      data.green_coefficient = total = (ru & 0xffff) / 65535.;
      ru >>= 16;
      data.red_coefficient = (1 - total) * (ru & 0xffff) / 65535.;
@@ -7937,11 +7947,11 @@ image_transform_png_set_background_set(const image_transform *this,
   else
      back.gray = (png_uint_16)data.red;

-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
-#else
-   png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
-#endif
+#  ifdef PNG_FLOATING_POINT_SUPPORTED
+      png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
+#  else
+      png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
+#  endif

   this->next->set(this->next, that, pp, pi);
 }
--- a/contrib/libtests/timepng.c
+++ b/contrib/libtests/timepng.c
@@ -1,8 +1,8 @@
 /* timepng.c
 *
- * Copyright (c) 2013,2016 John Cunningham Bowler
+ * Copyright (c) 2013 John Cunningham Bowler
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.1 [March 28, 2013]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -10,17 +10,15 @@
 *
 * Load an arbitrary number of PNG files (from the command line, or, if there
 * are no arguments on the command line, from stdin) then run a time test by
- * reading each file by row or by image (possibly with transforms in the latter
- * case).  The only output is a time as a floating point number of seconds with
- * 9 decimal digits.
+ * reading each file by row.  The test does nothing with the read result and
+ * does no transforms.  The only output is a time as a floating point number of
+ * seconds with 9 decimal digits.
 */
 #define _POSIX_C_SOURCE 199309L /* for clock_gettime */

 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <errno.h>
-#include <limits.h>

 #include <time.h>

@@ -37,61 +35,36 @@
 #  include "../../png.h"
 #endif

-/* The following is to support direct compilation of this file as C++ */
-#ifdef __cplusplus
-#  define voidcast(type, value) static_cast<type>(value)
-#else
-#  define voidcast(type, value) (value)
-#endif /* __cplusplus */
-
-#if ((defined(PNG_SEQUENTIAL_READ_SUPPORTED)) && defined(PNG_STDIO_SUPPORTED)\
-     && defined(PNG_EASY_ACCESS_SUPPORTED) && defined(PNG_INFO_IMAGE_SUPPORTED))
-typedef struct
+static int read_png(FILE *fp)
 {
-   FILE *input;
-   FILE *output;
-}  io_data;
-
-static PNG_CALLBACK(void, read_and_copy,
-      (png_structp png_ptr, png_bytep buffer, png_size_t cb))
-{
-   io_data *io = (io_data*)png_get_io_ptr(png_ptr);
-
-   if (fread(buffer, cb, 1, io->input) != 1)
-      png_error(png_ptr, strerror(errno));
-
-   if (fwrite(buffer, cb, 1, io->output) != 1)
-   {
-      perror("temporary file");
-      fprintf(stderr, "temporary file PNG write failed\n");
-      exit(1);
-   }
-}
-
-static void read_by_row(png_structp png_ptr, png_infop info_ptr,
-      FILE *write_ptr, FILE *read_ptr)
-{
-   /* These don't get freed on error, this is fine; the program immediately
-    * exits.
-    */
+   png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
+   png_infop info_ptr = NULL;
   png_bytep row = NULL, display = NULL;
-   io_data io_copy;

-   if (write_ptr != NULL)
+   if (png_ptr == NULL)
+      return 0;
+
+   if (setjmp(png_jmpbuf(png_ptr)))
   {
-      /* Set up for a copy to the temporary file: */
-      io_copy.input = read_ptr;
-      io_copy.output = write_ptr;
-      png_set_read_fn(png_ptr, &io_copy, read_and_copy);
+      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+      if (row != NULL) free(row);
+      if (display != NULL) free(display);
+      return 0;
   }

+   png_init_io(png_ptr, fp);
+
+   info_ptr = png_create_info_struct(png_ptr);
+   if (info_ptr == NULL)
+      png_error(png_ptr, "OOM allocating info structure");
+
   png_read_info(png_ptr, info_ptr);

   {
      png_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);

-      row = voidcast(png_bytep,malloc(rowbytes));
-      display = voidcast(png_bytep,malloc(rowbytes));
+      row = malloc(rowbytes);
+      display = malloc(rowbytes);

      if (row == NULL || display == NULL)
         png_error(png_ptr, "OOM allocating row buffers");
@@ -108,8 +81,7 @@ static void read_by_row(png_structp png_ptr, png_infop info_ptr,
            png_uint_32 y = height;

            /* NOTE: this trashes the row each time; interlace handling won't
-             * work, but this avoids memory thrashing for speed testing and is
-             * somewhat representative of an application that works row-by-row.
+             * work, but this avoids memory thrashing for speed testing.
             */
            while (y-- > 0)
               png_read_row(png_ptr, row, display);
@@ -119,51 +91,9 @@ static void read_by_row(png_structp png_ptr, png_infop info_ptr,

   /* Make sure to read to the end of the file: */
   png_read_end(png_ptr, info_ptr);
-
-   /* Free this up: */
+   png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
   free(row);
   free(display);
-}
-
-static PNG_CALLBACK(void, no_warnings, (png_structp png_ptr,
-         png_const_charp warning))
-{
-   (void)png_ptr;
-   (void)warning;
-}
-
-static int read_png(FILE *fp, png_int_32 transforms, FILE *write_file)
-{
-   png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,
-         no_warnings);
-   png_infop info_ptr = NULL;
-
-   if (png_ptr == NULL)
-      return 0;
-
-   if (setjmp(png_jmpbuf(png_ptr)))
-   {
-      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
-      return 0;
-   }
-
-#  ifdef PNG_BENIGN_ERRORS_SUPPORTED
-      png_set_benign_errors(png_ptr, 1/*allowed*/);
-#  endif
-   png_init_io(png_ptr, fp);
-
-   info_ptr = png_create_info_struct(png_ptr);
-
-   if (info_ptr == NULL)
-      png_error(png_ptr, "OOM allocating info structure");
-
-   if (transforms < 0)
-      read_by_row(png_ptr, info_ptr, write_file, fp);
-
-   else
-      png_read_png(png_ptr, info_ptr, transforms, NULL/*params*/);
-
-   png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
   return 1;
 }

@@ -178,7 +108,7 @@ static int mytime(struct timespec *t)
   return 0;
 }

-static int perform_one_test(FILE *fp, int nfiles, png_int_32 transforms)
+static int perform_one_test(FILE *fp, int nfiles)
 {
   int i;
   struct timespec before, after;
@@ -190,7 +120,7 @@ static int perform_one_test(FILE *fp, int nfiles, png_int_32 transforms)
   {
      for (i=0; i<nfiles; ++i)
      {
-         if (read_png(fp, transforms, NULL/*write*/))
+         if (read_png(fp))
         {
            if (ferror(fp))
            {
@@ -254,343 +184,120 @@ static int add_one_file(FILE *fp, char *name)

   if (ip != NULL)
   {
-      /* Read the file using libpng; this detects errors and also deals with
-       * files which contain data beyond the end of the file.
-       */
-      int ok = 0;
-      fpos_t pos;
-
-      if (fgetpos(fp, &pos))
+      int ch;
+      for (;;)
      {
-         /* Fatal error reading the start: */
-         perror("temporary file");
-         fprintf(stderr, "temporary file fgetpos error\n");
-         exit(1);
+         ch = getc(ip);
+         if (ch == EOF) break;
+         putc(ch, fp);
      }

-      if (read_png(ip, -1/*by row*/, fp/*output*/))
+      if (ferror(ip))
      {
-         if (ferror(ip))
-         {
-            perror(name);
-            fprintf(stderr, "%s: read error\n", name);
-         }
-
-         else
-            ok = 1; /* read ok */
+         perror(name);
+         fprintf(stderr, "%s: read error\n", name);
+         return 0;
      }

-      else
-         fprintf(stderr, "%s: file not added\n", name);
-
      (void)fclose(ip);

-      /* An error in the output is fatal; exit immediately: */
      if (ferror(fp))
      {
         perror("temporary file");
         fprintf(stderr, "temporary file write error\n");
-         exit(1);
-      }
-
-      if (ok)
-         return 1;
-
-      /* Did not read the file successfully, simply rewind the temporary
-       * file.  This must happen after the ferror check above to avoid clearing
-       * the error.
-       */
-      if (fsetpos(fp, &pos))
-      {
-         perror("temporary file");
-         fprintf(stderr, "temporary file fsetpos error\n");
-         exit(1);
+         return 0;
      }
   }

   else
   {
-      /* file open error: */
      perror(name);
      fprintf(stderr, "%s: open failed\n", name);
+      return 0;
   }

-   return 0; /* file not added */
-}
-
-static void
-usage(FILE *fp)
-{
-   if (fp != NULL) fclose(fp);
-
-   fprintf(stderr,
-"Usage:\n"
-" timepng --assemble <assembly> {files}\n"
-"  Read the files into <assembly>, output the count.  Options are ignored.\n"
-" timepng --dissemble <assembly> <count> [options]\n"
-"  Time <count> files from <assembly>, additional files may not be given.\n"
-" Otherwise:\n"
-"  Read the files into a temporary file and time the decode\n"
-"Transforms:\n"
-"  --by-image: read by image with png_read_png\n"
-"  --<transform>: implies by-image, use PNG_TRANSFORM_<transform>\n"
-"  Otherwise: read by row using png_read_row (to a single row buffer)\n"
-   /* ISO C90 string length max 509 */);fprintf(stderr,
-"{files}:\n"
-"  PNG files to copy into the assembly and time.  Invalid files are skipped\n"
-"  with appropriate error messages.  If no files are given the list of files\n"
-"  is read from stdin with each file name terminated by a newline\n"
-"Output:\n"
-"  For --assemble the output is the name of the assembly file followed by the\n"
-"  count of the files it contains; the arguments for --dissemble.  Otherwise\n"
-"  the output is the total decode time in seconds.\n");
-
-   exit(99);
+   return 1;
 }

 int main(int argc, char **argv)
 {
   int ok = 0;
-   int err = 0;
-   int nfiles = 0;
-   int transforms = -1; /* by row */
-   const char *assembly = NULL;
-   FILE *fp;
+   FILE *fp = tmpfile();

-   if (argc > 2 && strcmp(argv[1], "--assemble") == 0)
+   if (fp != NULL)
   {
-      /* Just build the test file, argv[2] is the file name. */
-      assembly = argv[2];
-      fp = fopen(assembly, "wb");
-      if (fp == NULL)
+      int err = 0;
+      int nfiles = 0;
+
+      if (argc > 1)
      {
-         perror(assembly);
-         fprintf(stderr, "timepng --assemble %s: could not open for write\n",
-               assembly);
-         usage(NULL);
-      }
+         int i;

-      argv += 2;
-      argc -= 2;
-   }
-
-   else if (argc > 3 && strcmp(argv[1], "--dissemble") == 0)
-   {
-      fp = fopen(argv[2], "rb");
-
-      if (fp == NULL)
-      {
-         perror(argv[2]);
-         fprintf(stderr, "timepng --dissemble %s: could not open for read\n",
-               argv[2]);
-         usage(NULL);
-      }
-
-      nfiles = atoi(argv[3]);
-      if (nfiles <= 0)
-      {
-         fprintf(stderr,
-               "timepng --dissemble <file> <count>: %s is not a count\n",
-               argv[3]);
-         exit(99);
-      }
-#ifdef __COVERITY__
-      else
-      {
-         nfiles &= PNG_UINT_31_MAX;
-      }
-#endif
-
-      argv += 3;
-      argc -= 3;
-   }
-
-   else /* Else use a temporary file */
-   {
-#ifndef __COVERITY__
-      fp = tmpfile();
-#else
-      /* Experimental. Coverity says tmpfile() is insecure because it
-       * generates predictable names.
-       *
-       * It is possible to satisfy Coverity by using mkstemp(); however,
-       * any platform supporting mkstemp() undoubtedly has a secure tmpfile()
-       * implementation as well, and doesn't need the fix.  Note that
-       * the fix won't work on platforms that don't support mkstemp().
-       *
-       * https://www.securecoding.cert.org/confluence/display/c/
-       * FIO21-C.+Do+not+create+temporary+files+in+shared+directories
-       * says that most historic implementations of tmpfile() provide
-       * only a limited number of possible temporary file names
-       * (usually 26) before file names are recycled. That article also
-       * provides a secure solution that unfortunately depends upon mkstemp().
-       */
-      char tmpfile[] = "timepng-XXXXXX";
-      int filedes;
-      umask(0177);
-      filedes = mkstemp(tmpfile);
-      if (filedes < 0)
-        fp = NULL;
-      else
-      {
-        fp = fdopen(filedes,"w+");
-        /* Hide the filename immediately and ensure that the file does
-         * not exist after the program ends
-         */
-        (void) unlink(tmpfile);
-      }
-#endif
-
-      if (fp == NULL)
-      {
-         perror("tmpfile");
-         fprintf(stderr, "timepng: could not open the temporary file\n");
-         exit(1); /* not a user error */
-      }
-   }
-
-   /* Handle the transforms: */
-   while (argc > 1 && argv[1][0] == '-' && argv[1][1] == '-')
-   {
-      const char *opt = *++argv + 2;
-
-      --argc;
-
-      /* Transforms turn on the by-image processing and maybe set some
-       * transforms:
-       */
-      if (transforms == -1)
-         transforms = PNG_TRANSFORM_IDENTITY;
-
-      if (strcmp(opt, "by-image") == 0)
-      {
-         /* handled above */
-      }
-
-#        define OPT(name) else if (strcmp(opt, #name) == 0)\
-         transforms |= PNG_TRANSFORM_ ## name
-
-      OPT(STRIP_16);
-      OPT(STRIP_ALPHA);
-      OPT(PACKING);
-      OPT(PACKSWAP);
-      OPT(EXPAND);
-      OPT(INVERT_MONO);
-      OPT(SHIFT);
-      OPT(BGR);
-      OPT(SWAP_ALPHA);
-      OPT(SWAP_ENDIAN);
-      OPT(INVERT_ALPHA);
-      OPT(STRIP_FILLER);
-      OPT(STRIP_FILLER_BEFORE);
-      OPT(STRIP_FILLER_AFTER);
-      OPT(GRAY_TO_RGB);
-      OPT(EXPAND_16);
-      OPT(SCALE_16);
-
-      else
-      {
-         fprintf(stderr, "timepng %s: unrecognized transform\n", opt);
-         usage(fp);
-      }
-   }
-
-   /* Handle the files: */
-   if (argc > 1 && nfiles > 0)
-      usage(fp); /* Additional files not valid with --dissemble */
-
-   else if (argc > 1)
-   {
-      int i;
-
-      for (i=1; i<argc; ++i)
-      {
-         if (nfiles == INT_MAX)
+         for (i=1; i<argc; ++i)
         {
-            fprintf(stderr, "%s: skipped, too many files\n", argv[i]);
-            break;
-         }
+            if (add_one_file(fp, argv[i]))
+               ++nfiles;

-         else if (add_one_file(fp, argv[i]))
-            ++nfiles;
-      }
-   }
-
-   else if (nfiles == 0) /* Read from stdin withoout --dissemble */
-   {
-      char filename[FILENAME_MAX+1];
-
-      while (fgets(filename, FILENAME_MAX+1, stdin))
-      {
-         size_t len = strlen(filename);
-
-         if (filename[len-1] == '\n')
-         {
-            filename[len-1] = 0;
-            if (nfiles == INT_MAX)
+            else
            {
-               fprintf(stderr, "%s: skipped, too many files\n", filename);
+               err = 1;
               break;
            }
-
-            else if (add_one_file(fp, filename))
-               ++nfiles;
-         }
-
-         else
-         {
-            fprintf(stderr, "timepng: file name too long: ...%s\n",
-               filename+len-32);
-            err = 1;
-            break;
         }
      }

-      if (ferror(stdin))
+      else
      {
-         fprintf(stderr, "timepng: stdin: read error\n");
-         err = 1;
-      }
-   }
+         char filename[FILENAME_MAX+1];

-   /* Perform the test, or produce the --assemble output: */
-   if (!err)
-   {
-      if (nfiles > 0)
-      {
-         if (assembly != NULL)
+         while (fgets(filename, FILENAME_MAX+1, stdin))
         {
-            if (fflush(fp) && !ferror(fp) && fclose(fp))
+            size_t len = strlen(filename);
+
+            if (filename[len-1] == '\n')
            {
-               perror(assembly);
-               fprintf(stderr, "%s: close failed\n", assembly);
+               filename[len-1] = 0;
+               if (add_one_file(fp, filename))
+                  ++nfiles;
+
+               else
+               {
+                  err = 1;
+                  break;
+               }
            }

            else
            {
-               printf("%s %d\n", assembly, nfiles);
-               fflush(stdout);
-               ok = !ferror(stdout);
+               fprintf(stderr, "timepng: truncated file name ...%s\n",
+                  filename+len-32);
+               err = 1;
+               break;
            }
         }

-         else
+         if (ferror(stdin))
         {
-            ok = perform_one_test(fp, nfiles, transforms);
-            (void)fclose(fp);
+            fprintf(stderr, "timepng: stdin: read error\n");
+            err = 1;
         }
      }

-      else
-         usage(fp);
+      if (!err)
+      {
+         if (nfiles > 0)
+            ok = perform_one_test(fp, nfiles);
+
+         else
+            fprintf(stderr, "usage: timepng {files} or ls files | timepng\n");
+      }
+
+      (void)fclose(fp);
   }

   else
-      (void)fclose(fp);
+      fprintf(stderr, "timepng: could not open temporary file\n");

   /* Exit code 0 on success. */
   return ok == 0;
 }
-#else /* !sufficient support */
-int main(void) { return 77; }
-#endif /* !sufficient support */
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng

- libpng version 1.6.22beta06 - May 5, 2016
+ libpng version 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng

 Based on:

- libpng versions 0.97, January 1998, through 1.6.22beta06 - May 5, 2016
+ libpng versions 0.97, January 1998, through 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 Copyright (c) 1998-2016 Glenn Randers-Pehrson

@@ -2842,7 +2842,7 @@ filter types.
       PNG_FILTER_UP    | PNG_FILTER_VALUE_UP   |
       PNG_FILTER_AVG   | PNG_FILTER_VALUE_AVG  |
       PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
-       PNG_ALL_FILTERS  | PNG_FAST_FILTERS);
+       PNG_ALL_FILTERS);

 If an application wants to start and stop using particular filters during
 compression, it should start out with all of the filters (to ensure that
@@ -4103,13 +4103,6 @@ be written:

      Write the image to the named file.

-   int png_image_write_to_memory (png_imagep image, void *memory,
-      png_alloc_size_t * PNG_RESTRICT memory_bytes,
-      int convert_to_8_bit, const void *buffer, ptrdiff_t row_stride,
-      const void *colormap));
-
-      Write the image to memory.
-
   int png_image_write_to_stdio(png_imagep image, FILE *file,
      int convert_to_8_bit, const void *buffer,
      png_int_32 row_stride, const void *colormap)
@@ -4387,9 +4380,8 @@ for any images with bit depths less than 8 bits/pixel.
 The 'method' parameter sets the main filtering method, which is
 currently only '0' in the PNG 1.2 specification.  The 'filters'
 parameter sets which filter(s), if any, should be used for each
-scanline.  Possible values are PNG_ALL_FILTERS, PNG_NO_FILTERS,
-or PNG_FAST_FILTERS to turn filtering on and off, or to turn on
-just the fast-decoding subset of filters, respectively.
+scanline.  Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+to turn filtering on and off, respectively.

 Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
 PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
@@ -4403,19 +4395,12 @@ means the first row must always be adaptively filtered, because libpng
 currently does not allocate the filter buffers until png_write_row()
 is called for the first time.)

-    filters = PNG_NO_FILTERS;
-    filters = PNG_ALL_FILTERS;
-    filters = PNG_FAST_FILTERS;
-
-    or
-
-    filters = PNG_FILTER_NONE | PNG_FILTER_SUB |
+    filters = PNG_FILTER_NONE | PNG_FILTER_SUB
              PNG_FILTER_UP | PNG_FILTER_AVG |
-              PNG_FILTER_PAETH;
+              PNG_FILTER_PAETH | PNG_ALL_FILTERS;

    png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
       filters);
-
              The second parameter can also be
              PNG_INTRAPIXEL_DIFFERENCING if you are
              writing a PNG to be embedded in a MNG
@@ -4790,8 +4775,7 @@ There are no substantial API changes between the non-deprecated parts of
 the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
 members of the main libpng control structures, png_struct and png_info,
 deprecated in earlier versions of libpng, has been completely removed from
-libpng 1.5, and new private "pngstruct.h", "pnginfo.h", and "pngdebug.h"
-header files were created.
+libpng 1.5.

 We no longer include zlib.h in png.h.  The include statement has been moved
 to pngstruct.h, where it is not accessible by applications. Applications that
@@ -5031,7 +5015,6 @@ includes the following:
     png_image_free()
   write functions
     png_image_write_to_file()
-     png_image_write_to_memory()
     png_image_write_to_stdio()

 Starting with libpng-1.6.0, you can configure libpng to prefix all exported
@@ -5345,7 +5328,7 @@ Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.

 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.22beta06 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.21 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.

 Libpng only has two year fields.  One is a 2-byte unsigned integer
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "May 5, 2016"
+.TH LIBPNG 3 "January 15, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.22beta06
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.21
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -229,8 +229,6 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.22beta06

 \fBint png_image_write_to_file (png_imagep \fP\fIimage\fP\fB, const char \fP\fI*file\fP\fB, int \fP\fIconvert_to_8bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP

-\fBint png_image_write_to_memory (png_imagep \fP\fIimage\fP\fB, void \fP\fI*memory\fP\fB, png_alloc_size_t * PNG_RESTRICT \fP\fImemory_bytes\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, const void \fI*colormap)\fP\fB);\fP
-
 \fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap)\fP\fB);\fP

 \fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
@@ -510,7 +508,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
 .SH LIBPNG.TXT
 libpng-manual.txt - A description on how to use and modify libpng

- libpng version 1.6.22beta06 - May 5, 2016
+ libpng version 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -521,7 +519,7 @@ libpng-manual.txt - A description on how to use and modify libpng

 Based on:

- libpng versions 0.97, January 1998, through 1.6.22beta06 - May 5, 2016
+ libpng versions 0.97, January 1998, through 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 Copyright (c) 1998-2016 Glenn Randers-Pehrson

@@ -3352,7 +3350,7 @@ filter types.
       PNG_FILTER_UP    | PNG_FILTER_VALUE_UP   |
       PNG_FILTER_AVG   | PNG_FILTER_VALUE_AVG  |
       PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
-       PNG_ALL_FILTERS  | PNG_FAST_FILTERS);
+       PNG_ALL_FILTERS);

 If an application wants to start and stop using particular filters during
 compression, it should start out with all of the filters (to ensure that
@@ -4613,13 +4611,6 @@ be written:

      Write the image to the named file.

-   int png_image_write_to_memory (png_imagep image, void *memory,
-      png_alloc_size_t * PNG_RESTRICT memory_bytes,
-      int convert_to_8_bit, const void *buffer, ptrdiff_t row_stride,
-      const void *colormap));
-
-      Write the image to memory.
-
   int png_image_write_to_stdio(png_imagep image, FILE *file,
      int convert_to_8_bit, const void *buffer,
      png_int_32 row_stride, const void *colormap)
@@ -4897,9 +4888,8 @@ for any images with bit depths less than 8 bits/pixel.
 The 'method' parameter sets the main filtering method, which is
 currently only '0' in the PNG 1.2 specification.  The 'filters'
 parameter sets which filter(s), if any, should be used for each
-scanline.  Possible values are PNG_ALL_FILTERS, PNG_NO_FILTERS,
-or PNG_FAST_FILTERS to turn filtering on and off, or to turn on
-just the fast-decoding subset of filters, respectively.
+scanline.  Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+to turn filtering on and off, respectively.

 Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
 PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
@@ -4913,19 +4903,12 @@ means the first row must always be adaptively filtered, because libpng
 currently does not allocate the filter buffers until png_write_row()
 is called for the first time.)

-    filters = PNG_NO_FILTERS;
-    filters = PNG_ALL_FILTERS;
-    filters = PNG_FAST_FILTERS;
-
-    or
-
-    filters = PNG_FILTER_NONE | PNG_FILTER_SUB |
+    filters = PNG_FILTER_NONE | PNG_FILTER_SUB
              PNG_FILTER_UP | PNG_FILTER_AVG |
-              PNG_FILTER_PAETH;
+              PNG_FILTER_PAETH | PNG_ALL_FILTERS;

    png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
       filters);
-
              The second parameter can also be
              PNG_INTRAPIXEL_DIFFERENCING if you are
              writing a PNG to be embedded in a MNG
@@ -5300,8 +5283,7 @@ There are no substantial API changes between the non-deprecated parts of
 the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
 members of the main libpng control structures, png_struct and png_info,
 deprecated in earlier versions of libpng, has been completely removed from
-libpng 1.5, and new private "pngstruct.h", "pnginfo.h", and "pngdebug.h"
-header files were created.
+libpng 1.5.

 We no longer include zlib.h in png.h.  The include statement has been moved
 to pngstruct.h, where it is not accessible by applications. Applications that
@@ -5541,7 +5523,6 @@ includes the following:
     png_image_free()
   write functions
     png_image_write_to_file()
-     png_image_write_to_memory()
     png_image_write_to_stdio()

 Starting with libpng-1.6.0, you can configure libpng to prefix all exported
@@ -5855,7 +5836,7 @@ Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.

 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.22beta06 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.21 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.

 Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -5953,11 +5934,11 @@ the first widely used release:
 ...
 1.0.19                  10    10019  10.so.0.19[.0]
 ...
- 1.2.56                  13    10256  12.so.0.56[.0]
+ 1.2.53                  13    10253  12.so.0.53[.0]
 ...
- 1.5.25                  15    10525  15.so.15.25[.0]
+ 1.5.23                  15    10523  15.so.15.23[.0]
 ...
- 1.6.22                  16    10622  16.so.16.22[.0]
+ 1.6.21                  16    10621  16.so.16.21[.0]

 Henceforth the source version will match the shared-library minor
 and patch numbers; the shared-library major version number will be
@@ -6013,7 +5994,7 @@ possible without all of you.

 Thanks to Frank J. T. Wojcik for helping with the documentation.

-Libpng version 1.6.22beta06 - May 5, 2016:
+Libpng version 1.6.21 - January 15, 2016:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).

@@ -6038,7 +6019,7 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.0.7, July 1, 2000 through 1.6.22beta06, May 5, 2016 are
+libpng versions 1.0.7, July 1, 2000, through 1.6.21, January 15, 2016, are
 Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
@@ -6060,10 +6041,6 @@ and with the following additions to the disclaimer:
   risk of satisfactory quality, performance, accuracy, and effort is with
   the user.

-Some files in the "contrib" directory and some configure-generated
-files that are distributed with libpng have other copyright owners and
-are released under other open source licenses.
-
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 libpng-0.96, and are distributed according to the same disclaimer and
@@ -6087,9 +6064,6 @@ Contributing Authors:
   Greg Roelofs
   Tom Tanner

-Some files in the "scripts" directory have other copyright owners
-but are released under this license.
-
 libpng versions 0.5, May 1995, through 0.88, January 1996, are
 Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.

@@ -6130,29 +6104,6 @@ appreciated.

 END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.

-TRADEMARK:
-
-The name "libpng" has not been registered by the Copyright owner
-as a trademark in any jurisdiction.  However, because libpng has
-been distributed and maintained world-wide, continually since 1995,
-the Copyright owner claims "common-law trademark protection" in any
-jurisdiction where common-law trademark is recognized.
-
-OSI CERTIFICATION:
-
-Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
-a certification mark of the Open Source Initiative. OSI has not addressed
-the additional disclaimers inserted at version 1.0.7.
-
-EXPORT CONTROL:
-
-The Copyright owner believes that the Export Control Classification
-Number (ECCN) for libpng is EAR99, which means not subject to export
-controls or International Traffic in Arms Regulations (ITAR) because
-it is open source, publicly available software, that does not contain
-any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
-734.7(b).
-
 A "png_get_copyright" function is available, for convenient use in "about"
 boxes and the like:

@@ -6161,9 +6112,13 @@ boxes and the like:
 Also, the PNG logo (in PNG format, of course) is supplied in the
 files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).

+Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
+a certification mark of the Open Source Initiative. OSI has not addressed
+the additional disclaimers inserted at version 1.0.7.
+
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-May 5, 2016
+January 15, 2016

 .\" end of man page

--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "May 5, 2016"
+.TH LIBPNGPF 3 "January 15, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.22beta06
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.21
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "May 5, 2016"
+.TH PNG 5 "January 15, 2016"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
--- a/png.c
+++ b/png.c
@@ -14,7 +14,7 @@
 #include "pngpriv.h"

 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_22beta06 Your_png_h_is_not_version_1_6_22beta06;
+typedef png_libpng_version_1_6_21 Your_png_h_is_not_version_1_6_21;

 /* Tells libpng that we have already handled the first "num_bytes" bytes
 * of the PNG file signature.  If the PNG data is embedded into another
@@ -775,14 +775,14 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
   return PNG_STRING_NEWLINE \
-      "libpng version 1.6.22beta06 - May 5, 2016" PNG_STRING_NEWLINE \
+      "libpng version 1.6.21 - January 15, 2016" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson" \
      PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE;
 #  else
-   return "libpng version 1.6.22beta06 - May 5, 2016\
+   return "libpng version 1.6.21 - January 15, 2016\
      Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\
      Copyright (c) 1996-1997 Andreas Dilger\
      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@

 /* png.h - header file for PNG reference library
 *
- * libpng version 1.6.22beta06, May 5, 2016
+ * libpng version 1.6.21, January 15, 2016
 *
 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -12,7 +12,7 @@
 * Authors and maintainers:
 *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
 *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.6.22beta06, May 5, 2016:
+ *   libpng versions 0.97, January 1998, through 1.6.21, January 15, 2016:
 *     Glenn Randers-Pehrson.
 *   See also "Contributing Authors", below.
 */
@@ -25,11 +25,7 @@
 *
 * This code is released under the libpng license.
 *
- * Some files in the "contrib" directory and some configure-generated
- * files that are distributed with libpng have other copyright owners and
- * are released under other open source licenses.
- *
- * libpng versions 1.0.7, July 1, 2000 through 1.6.22beta06, May 5, 2016 are
+ * libpng versions 1.0.7, July 1, 2000, through 1.6.21, January 15, 2016, are
 * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 * derived from libpng-1.0.6, and are distributed according to the same
 * disclaimer and license as libpng-1.0.6 with the following individuals
@@ -51,10 +47,6 @@
 *    risk of satisfactory quality, performance, accuracy, and effort is with
 *    the user.
 *
- * Some files in the "contrib" directory have other copyright owners and
- * are released under other open source licenses.
- *
- *
 * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 * libpng-0.96, and are distributed according to the same disclaimer and
@@ -65,9 +57,6 @@
 *    Glenn Randers-Pehrson
 *    Willem van Schaik
 *
- * Some files in the "scripts" directory have different copyright owners
- * but are also released under this license.
- *
 * libpng versions 0.89, June 1996, through 0.96, May 1997, are
 * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
 * and are distributed according to the same disclaimer and license as
@@ -81,9 +70,6 @@
 *    Greg Roelofs
 *    Tom Tanner
 *
- * Some files in the "scripts" directory have other copyright owners
- * but are released under this license.
- *
 * libpng versions 0.5, May 1995, through 0.88, January 1996, are
 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
@@ -123,29 +109,6 @@
 * appreciated.
 *
 * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
- *
- * TRADEMARK:
- *
- * The name "libpng" has not been registered by the Copyright owner
- * as a trademark in any jurisdiction.  However, because libpng has
- * been distributed and maintained world-wide, continually since 1995,
- * the Copyright owner claims "common-law trademark protection" in any
- * jurisdiction where common-law trademark is recognized.
- *
- * OSI CERTIFICATION:
- *
- * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
- * a certification mark of the Open Source Initiative. OSI has not addressed
- * the additional disclaimers inserted at version 1.0.7.
- *
- * EXPORT CONTROL:
- *
- * The Copyright owner believes that the Export Control Classification
- * Number (ECCN) for libpng is EAR99, which means not subject to export
- * controls or International Traffic in Arms Regulations (ITAR) because
- * it is open source, publicly available software, that does not contain
- * any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
- * 734.7(b).
 */

 /*
@@ -158,6 +121,12 @@
 * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
 */

+/*
+ * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
+ * a certification mark of the Open Source Initiative. OSI has not addressed
+ * the additional disclaimers inserted at version 1.0.7.
+ */
+
 /*
 * The contributing authors would like to thank all those who helped
 * with testing, bug fixes, and patience.  This wouldn't have been
@@ -213,11 +182,11 @@
 *    ...
 *    1.0.19                  10    10019  10.so.0.19[.0]
 *    ...
- *    1.2.56                  13    10256  12.so.0.56[.0]
+ *    1.2.53                  13    10253  12.so.0.53[.0]
 *    ...
- *    1.5.25                  15    10525  15.so.15.25[.0]
+ *    1.5.23                  15    10523  15.so.15.23[.0]
 *    ...
- *    1.6.22                  16    10622  16.so.16.22[.0]
+ *    1.6.21                  16    10621  16.so.16.21[.0]
 *
 *    Henceforth the source version will match the shared-library major
 *    and minor numbers; the shared-library major version number will be
@@ -245,13 +214,13 @@
 * Y2K compliance in libpng:
 * =========================
 *
- *    May 5, 2016
+ *    January 15, 2016
 *
 *    Since the PNG Development group is an ad-hoc body, we can't make
 *    an official declaration.
 *
 *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.6.22beta06 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.21 are Y2K compliant.  It is my belief that
 *    earlier versions were also Y2K compliant.
 *
 *    Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -313,9 +282,9 @@
 */

 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.22beta06"
+#define PNG_LIBPNG_VER_STRING "1.6.21"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.6.22beta06 - May 5, 2016\n"
+     " libpng version 1.6.21 - January 15, 2016\n"

 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -323,13 +292,13 @@
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   6
-#define PNG_LIBPNG_VER_RELEASE 22
+#define PNG_LIBPNG_VER_RELEASE 21

 /* This should match the numeric part of the final component of
 * PNG_LIBPNG_VER_STRING, omitting any leading zero:
 */

-#define PNG_LIBPNG_VER_BUILD  06
+#define PNG_LIBPNG_VER_BUILD  0

 /* Release Status */
 #define PNG_LIBPNG_BUILD_ALPHA    1
@@ -346,7 +315,7 @@
 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
                                       PNG_LIBPNG_BUILD_PRIVATE */

-#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_BETA
+#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE

 /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
 * We must not include leading zeros.
@@ -354,7 +323,7 @@
 * version 1.0.0 was mis-numbered 100 instead of 10000).  From
 * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
 */
-#define PNG_LIBPNG_VER 10622 /* 1.6.22 */
+#define PNG_LIBPNG_VER 10621 /* 1.6.21 */

 /* Library configuration: these options cannot be changed after
 * the library has been built.
@@ -464,7 +433,7 @@ extern "C" {
 /* This triggers a compiler error in png.c, if png.c and png.h
 * do not agree upon the version number.
 */
-typedef char* png_libpng_version_1_6_22beta06;
+typedef char* png_libpng_version_1_6_21;

 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
 *
@@ -765,22 +734,24 @@ typedef png_unknown_chunk * * png_unknown_chunkpp;
 * data in the info_struct to be written into the output file.  The values
 * of the PNG_INFO_<chunk> defines should NOT be changed.
 */
-#define PNG_INFO_gAMA 0x0001U
-#define PNG_INFO_sBIT 0x0002U
-#define PNG_INFO_cHRM 0x0004U
-#define PNG_INFO_PLTE 0x0008U
-#define PNG_INFO_tRNS 0x0010U
-#define PNG_INFO_bKGD 0x0020U
-#define PNG_INFO_hIST 0x0040U
-#define PNG_INFO_pHYs 0x0080U
-#define PNG_INFO_oFFs 0x0100U
-#define PNG_INFO_tIME 0x0200U
-#define PNG_INFO_pCAL 0x0400U
-#define PNG_INFO_sRGB 0x0800U  /* GR-P, 0.96a */
-#define PNG_INFO_iCCP 0x1000U  /* ESR, 1.0.6 */
-#define PNG_INFO_sPLT 0x2000U  /* ESR, 1.0.6 */
-#define PNG_INFO_sCAL 0x4000U  /* ESR, 1.0.6 */
-#define PNG_INFO_IDAT 0x8000U  /* ESR, 1.0.6 */
+#define PNG_INFO_gAMA 0x0001
+#define PNG_INFO_sBIT 0x0002
+#define PNG_INFO_cHRM 0x0004
+#define PNG_INFO_PLTE 0x0008
+#define PNG_INFO_tRNS 0x0010
+#define PNG_INFO_bKGD 0x0020
+#define PNG_INFO_hIST 0x0040
+#define PNG_INFO_pHYs 0x0080
+#define PNG_INFO_oFFs 0x0100
+#define PNG_INFO_tIME 0x0200
+#define PNG_INFO_pCAL 0x0400
+#define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */
+#define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */
+#define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */
+#define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */
+#if INT_MAX >= 0x8000 /* else this might break */
+#define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */
+#endif

 /* This is used for the transformation routines, as some of them
 * change these values for the row.  It also should enable using
@@ -1351,7 +1322,7 @@ PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
 #endif

 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-#define PNG_READ_16_TO_8_SUPPORTED /* Name prior to 1.5.4 */
+#define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
 /* Strip the second byte of information from a 16-bit depth file. */
 PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
 #endif
@@ -1502,8 +1473,8 @@ PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
 #define PNG_FILTER_UP      0x20
 #define PNG_FILTER_AVG     0x40
 #define PNG_FILTER_PAETH   0x80
-#define PNG_FAST_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP)
-#define PNG_ALL_FILTERS (PNG_FAST_FILTERS | PNG_FILTER_AVG | PNG_FILTER_PAETH)
+#define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
+                         PNG_FILTER_AVG | PNG_FILTER_PAETH)

 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
 * These defines should NOT be changed.
@@ -1780,21 +1751,21 @@ PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
 #define PNG_SET_WILL_FREE_DATA 1
 #define PNG_USER_WILL_FREE_DATA 2
 /* Flags for png_ptr->free_me and info_ptr->free_me */
-#define PNG_FREE_HIST 0x0008U
-#define PNG_FREE_ICCP 0x0010U
-#define PNG_FREE_SPLT 0x0020U
-#define PNG_FREE_ROWS 0x0040U
-#define PNG_FREE_PCAL 0x0080U
-#define PNG_FREE_SCAL 0x0100U
+#define PNG_FREE_HIST 0x0008
+#define PNG_FREE_ICCP 0x0010
+#define PNG_FREE_SPLT 0x0020
+#define PNG_FREE_ROWS 0x0040
+#define PNG_FREE_PCAL 0x0080
+#define PNG_FREE_SCAL 0x0100
 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
-#  define PNG_FREE_UNKN 0x0200U
+#  define PNG_FREE_UNKN 0x0200
 #endif
-/*      PNG_FREE_LIST 0x0400U   removed in 1.6.0 because it is ignored */
-#define PNG_FREE_PLTE 0x1000U
-#define PNG_FREE_TRNS 0x2000U
-#define PNG_FREE_TEXT 0x4000U
-#define PNG_FREE_ALL  0x7fffU
-#define PNG_FREE_MUL  0x4220U /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
+/*      PNG_FREE_LIST 0x0400    removed in 1.6.0 because it is ignored */
+#define PNG_FREE_PLTE 0x1000
+#define PNG_FREE_TRNS 0x2000
+#define PNG_FREE_TEXT 0x4000
+#define PNG_FREE_ALL  0x7fff
+#define PNG_FREE_MUL  0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */

 #ifdef PNG_USER_MEM_SUPPORTED
 PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
@@ -2918,19 +2889,12 @@ typedef struct
    * is the minimum 'row stride', the minimum count of components between each
    * row.  For a color-mapped image this is the minimum number of bytes in a
    * row.
-    *
-    * WARNING: this macro overflows for some images with more than one component
-    * and very large image widths.  libpng will refuse to process an image where
-    * this macro would overflow.
    */

 #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
   (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
   /* Return the size, in bytes, of an image buffer given a png_image and a row
    * stride - the number of components to leave space for in each row.
-    *
-    * WARNING: this macro overflows a 32-bit integer for some large PNG images,
-    * libpng will refuse to process an image where such an overflow would occur.
    */

 #define PNG_IMAGE_SIZE(image)\
@@ -3051,6 +3015,7 @@ PNG_EXPORT(238, void, png_image_free, (png_imagep image));
 #endif /* SIMPLIFIED_READ */

 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+#ifdef PNG_STDIO_SUPPORTED
 /* WRITE APIS
 * ----------
 * For write you must initialize a png_image structure to describe the image to
@@ -3067,7 +3032,6 @@ PNG_EXPORT(238, void, png_image_free, (png_imagep image));
 *    values do not correspond to the colors in sRGB.
 * colormap_entries: set to the number of entries in the color-map (0 to 256)
 */
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
 PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
   const char *file, int convert_to_8bit, const void *buffer,
   png_int_32 row_stride, const void *colormap));
@@ -3077,9 +3041,8 @@ PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
   int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
   const void *colormap));
   /* Write the image to the given (FILE*). */
-#endif /* SIMPLIFIED_WRITE_STDIO */

-/* With all write APIs if image is in one of the linear formats with 16-bit
+/* With both write APIs if image is in one of the linear formats with 16-bit
 * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
 * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
 * encoded PNG file is written.
@@ -3091,103 +3054,13 @@ PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
 *
 * With all APIs row_stride is handled as in the read APIs - it is the spacing
 * from one row to the next in component sized units (1 or 2 bytes) and if
- * negative indicates a bottom-up row layout in the buffer.  If row_stride is
- * zero, libpng will calculate it for you from the image width and number of
- * channels.
+ * negative indicates a bottom-up row layout in the buffer.  If row_stride is zero,
+ * libpng will calculate it for you from the image width and number of channels.
 *
- * Note that the write API does not support interlacing, sub-8-bit pixels or
- * most ancillary chunks.  If you need to write text chunks (e.g. for copyright
- * notices) you need to use one of the other APIs.
+ * Note that the write API does not support interlacing, sub-8-bit pixels, indexed
+ * PNG (color_type 3) or most ancillary chunks.
 */
-
-PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
-   png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8_bit,
-   const void *buffer, png_int_32 row_stride, const void *colormap));
-   /* Write the image to the given memory buffer.  The function both writes the
-    * whole PNG data stream to *memory and updates *memory_bytes with the count
-    * of bytes written.
-    *
-    * 'memory' may be NULL.  In this case *memory_bytes is not read however on
-    * success the number of bytes which would have been written will still be
-    * stored in *memory_bytes.  On failure *memory_bytes will contain 0.
-    *
-    * If 'memory' is not NULL it must point to memory[*memory_bytes] of
-    * writeable memory.
-    *
-    * If the function returns success memory[*memory_bytes] (if 'memory' is not
-    * NULL) contains the written PNG data.  *memory_bytes will always be less
-    * than or equal to the original value.
-    *
-    * If the function returns false and *memory_bytes was not changed an error
-    * occured during write.  If *memory_bytes was changed, or is not 0 if
-    * 'memory' was NULL, the write would have succeeded but for the memory
-    * buffer being too small.  *memory_bytes contains the required number of
-    * bytes and will be bigger that the original value.
-    */
-
-#define png_image_write_get_memory_size(image, size, convert_to_8_bit, buffer,\
-   row_stride, colormap)\
-   png_image_write_to_memory(&(image), 0, &(size), convert_to_8_bit, buffer,\
-         row_stride, colormap)
-   /* Return the amount of memory in 'size' required to compress this image.
-    * The png_image structure 'image' must be filled in as in the above
-    * function and must not be changed before the actual write call, the buffer
-    * and all other parameters must also be identical to that in the final
-    * write call.  The 'size' variable need not be initialized.
-    *
-    * NOTE: the macro returns true/false, if false is returned 'size' will be
-    * set to zero and the write failed and probably will fail if tried again.
-    */
-
-/* You can pre-allocate the buffer by making sure it is of sufficient size
- * regardless of the amount of compression achieved.  The buffer size will
- * always be bigger than the original image and it will never be filled.  The
- * following macros are provided to assist in allocating the buffer.
- */
-#define PNG_IMAGE_DATA_SIZE(image) (PNG_IMAGE_SIZE(image)+(image).height)
-   /* The number of uncompressed bytes in the PNG byte encoding of the image;
-    * uncompressing the PNG IDAT data will give this number of bytes.
-    *
-    * NOTE: while PNG_IMAGE_SIZE cannot overflow for an image in memory this
-    * macro can because of the extra bytes used in the PNG byte encoding.  You
-    * need to avoid this macro if your image size approaches 2^30 in width or
-    * height.  The same goes for the remainder of these macros; they all produce
-    * bigger numbers than the actual in-memory image size.
-    */
-#ifndef PNG_ZLIB_MAX_SIZE
-#  define PNG_ZLIB_MAX_SIZE(b) ((b)+(((b)+7U)>>3)+(((b)+63U)>>6)+11U)
-   /* An upper bound on the number of compressed bytes given 'b' uncompressed
-    * bytes.  This is based on deflateBounds() in zlib; different
-    * implementations of zlib compression may conceivably produce more data so
-    * if your zlib implementation is not zlib itself redefine this macro
-    * appropriately.
-    */
-#endif
-
-#define PNG_IMAGE_COMPRESSED_SIZE_MAX(image)\
-   PNG_ZLIB_MAX_SIZE((png_alloc_size_t)PNG_IMAGE_DATA_SIZE(image))
-   /* An upper bound on the size of the data in the PNG IDAT chunks. */
-
-#define PNG_IMAGE_PNG_SIZE_MAX_(image, image_size)\
-   ((8U/*sig*/+25U/*IHDR*/+16U/*gAMA*/+44U/*cHRM*/+12U/*IEND*/+\
-    (((image).format&PNG_FORMAT_FLAG_COLORMAP)?/*colormap: PLTE, tRNS*/\
-     12U+3U*(image).colormap_entries/*PLTE data*/+\
-     (((image).format&PNG_FORMAT_FLAG_ALPHA)?\
-      12U/*tRNS*/+(image).colormap_entries:0U):0U)+\
-    12U)+(12U*((image_size)/PNG_ZBUF_SIZE))/*IDAT*/+(image_size))
-   /* A helper for the following macro; if your compiler cannot handle the
-    * following macro use this one with the result of
-    * PNG_IMAGE_COMPRESSED_SIZE_MAX(image) as the second argument (most
-    * compilers should handle this just fine.)
-    */
-
-#define PNG_IMAGE_PNG_SIZE_MAX(image)\
-   PNG_IMAGE_PNG_SIZE_MAX_(image, PNG_IMAGE_COMPRESSED_SIZE_MAX(image))
-   /* An upper bound on the total length of the PNG data stream for 'image'.
-    * The result is of type png_alloc_size_t, on 32-bit systems this may
-    * overflow even though PNG_IMAGE_DATA_SIZE does not overflow; the write will
-    * run out of buffer space but return a corrected size which should work.
-    */
+#endif /* STDIO */
 #endif /* SIMPLIFIED_WRITE */
 /*******************************************************************************
 *  END OF SIMPLIFIED API
@@ -3245,7 +3118,7 @@ PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
 * one to use is one more than this.)
 */
 #ifdef PNG_EXPORT_LAST_ORDINAL
-  PNG_EXPORT_LAST_ORDINAL(245);
+  PNG_EXPORT_LAST_ORDINAL(244);
 #endif

 #ifdef __cplusplus
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@

 /* pngconf.h - machine configurable file for libpng
 *
- * libpng version 1.6.22beta06, May 5, 2016
+ * libpng version 1.6.21, January 15, 2016
 *
 * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
--- a/pngget.c
+++ b/pngget.c
@@ -456,11 +456,11 @@ png_get_pHYs_dpi(png_const_structrp png_ptr, png_const_inforp info_ptr,
   return (retval);
 }
 #endif /* pHYs */
-#endif /* INCH_CONVERSIONS */
+#endif  /* INCH_CONVERSIONS */

 /* png_get_channels really belongs in here, too, but it's been around longer */

-#endif /* EASY_ACCESS */
+#endif  /* EASY_ACCESS */


 png_byte PNGAPI
@@ -1142,19 +1142,19 @@ png_get_compression_buffer_size(png_const_structrp png_ptr)
      return 0;

 #ifdef PNG_WRITE_SUPPORTED
-   if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
 #endif
   {
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
-      return png_ptr->IDAT_read_size;
+         return png_ptr->IDAT_read_size;
 #else
-      return PNG_IDAT_READ_SIZE;
+         return PNG_IDAT_READ_SIZE;
 #endif
   }

 #ifdef PNG_WRITE_SUPPORTED
-   else
-      return png_ptr->zbuffer_size;
+      else
+         return png_ptr->zbuffer_size;
 #endif
 }

--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1,7 +1,7 @@

 /* pngpriv.h - private declarations for use inside libpng
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.21 [January 15, 2016]
 * Copyright (c) 1998-2002,2004,2006-2015 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.)
@@ -1915,8 +1915,6 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
    */
 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
-   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
 #endif

 PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
--- a/pngread.c
+++ b/pngread.c
@@ -3848,16 +3848,16 @@ png_image_read_direct(png_voidp argument)
            else
               filler = 255;

-#ifdef PNG_FORMAT_AFIRST_SUPPORTED
-            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
-            {
-               where = PNG_FILLER_BEFORE;
-               change &= ~PNG_FORMAT_FLAG_AFIRST;
-            }
+#           ifdef PNG_FORMAT_AFIRST_SUPPORTED
+               if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
+               {
+                  where = PNG_FILLER_BEFORE;
+                  change &= ~PNG_FORMAT_FLAG_AFIRST;
+               }

-            else
-#endif
-            where = PNG_FILLER_AFTER;
+               else
+#           endif
+               where = PNG_FILLER_AFTER;

            png_set_add_alpha(png_ptr, filler, where);
         }
@@ -3965,12 +3965,12 @@ png_image_read_direct(png_voidp argument)
      if (info_ptr->bit_depth == 16)
         info_format |= PNG_FORMAT_FLAG_LINEAR;

-#ifdef PNG_FORMAT_BGR_SUPPORTED
-      if ((png_ptr->transformations & PNG_BGR) != 0)
-         info_format |= PNG_FORMAT_FLAG_BGR;
-#endif
+#     ifdef PNG_FORMAT_BGR_SUPPORTED
+         if ((png_ptr->transformations & PNG_BGR) != 0)
+            info_format |= PNG_FORMAT_FLAG_BGR;
+#     endif

-#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+#     ifdef PNG_FORMAT_AFIRST_SUPPORTED
         if (do_local_background == 2)
         {
            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
@@ -4071,84 +4071,58 @@ png_image_finish_read(png_imagep image, png_const_colorp background,
 {
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
-      /* Check for row_stride overflow.  This check is not performed on the
-       * original PNG format because it may not occur in the output PNG format
-       * and libpng deals with the issues of reading the original.
-       */
-      const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
+      png_uint_32 check;

-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
+      if (row_stride == 0)
+         row_stride = PNG_IMAGE_ROW_STRIDE(*image);
+
+      if (row_stride < 0)
+         check = -row_stride;
+
+      else
+         check = row_stride;
+
+      if (image->opaque != NULL && buffer != NULL &&
+         check >= PNG_IMAGE_ROW_STRIDE(*image))
      {
-         png_uint_32 check;
-         const png_uint_32 png_row_stride = image->width * channels;
-
-         if (row_stride == 0)
-            row_stride = (png_int_32)/*SAFE*/png_row_stride;
-
-         if (row_stride < 0)
-            check = -row_stride;
-
-         else
-            check = row_stride;
-
-         if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
+         if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
+            (image->colormap_entries > 0 && colormap != NULL))
         {
-            /* Now check for overflow of the image buffer calculation; this
-             * limits the whole image size to 32 bits for API compatibility with
-             * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
+            int result;
+            png_image_read_control display;
+
+            memset(&display, 0, (sizeof display));
+            display.image = image;
+            display.buffer = buffer;
+            display.row_stride = row_stride;
+            display.colormap = colormap;
+            display.background = background;
+            display.local_row = NULL;
+
+            /* Choose the correct 'end' routine; for the color-map case all the
+             * setup has already been done.
             */
-            if (image->height <= 0xFFFFFFFF/png_row_stride)
-            {
-               if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
-                  (image->colormap_entries > 0 && colormap != NULL))
-               {
-                  int result;
-                  png_image_read_control display;
-
-                  memset(&display, 0, (sizeof display));
-                  display.image = image;
-                  display.buffer = buffer;
-                  display.row_stride = row_stride;
-                  display.colormap = colormap;
-                  display.background = background;
-                  display.local_row = NULL;
-
-                  /* Choose the correct 'end' routine; for the color-map case
-                   * all the setup has already been done.
-                   */
-                  if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
-                     result = png_safe_execute(image,
-                                    png_image_read_colormap, &display) &&
-                              png_safe_execute(image,
-                                    png_image_read_colormapped, &display);
-
-                  else
-                     result =
-                        png_safe_execute(image,
-                              png_image_read_direct, &display);
-
-                  png_image_free(image);
-                  return result;
-               }
-
-               else
-                  return png_image_error(image,
-                     "png_image_finish_read[color-map]: no color-map");
-            }
+            if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
+               result =
+                  png_safe_execute(image, png_image_read_colormap, &display) &&
+                  png_safe_execute(image, png_image_read_colormapped, &display);

            else
-               return png_image_error(image,
-                  "png_image_finish_read: image too large");
+               result =
+                  png_safe_execute(image, png_image_read_direct, &display);
+
+            png_image_free(image);
+            return result;
         }

         else
            return png_image_error(image,
-               "png_image_finish_read: invalid argument");
+               "png_image_finish_read[color-map]: no color-map");
      }

      else
         return png_image_error(image,
-            "png_image_finish_read: row_stride too large");
+            "png_image_finish_read: invalid argument");
   }

   else if (image != NULL)
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -1,8 +1,8 @@

 /* pngrtran.c - transforms the data in a row for PNG readers
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.19 [November 12, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 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.)
 *
@@ -159,7 +159,7 @@ png_set_background(png_structrp png_ptr,
   png_set_background_fixed(png_ptr, background_color, background_gamma_code,
      need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
 }
-#  endif /* FLOATING_POINT */
+#  endif  /* FLOATING_POINT */
 #endif /* READ_BACKGROUND */

 /* Scale 16-bit depth files to 8-bit depth.  If both of these are set then the
@@ -289,12 +289,9 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
    * is expected to be 1 or greater, but this range test allows for some
    * viewing correction values.  The intent is to weed out users of this API
    * who use the inverse of the gamma value accidentally!  Since some of these
-    * values are reasonable this may have to be changed:
-    *
-    * 1.6.x: changed from 0.07..3 to 0.01..100 (to accomodate the optimal 16-bit
-    * gamma of 36, and its reciprocal.)
+    * values are reasonable this may have to be changed.
    */
-   if (output_gamma < 1000 || output_gamma > 10000000)
+   if (output_gamma < 70000 || output_gamma > 300000)
      png_error(png_ptr, "output gamma out of expected range");

   /* The default file gamma is the inverse of the output gamma; the output
@@ -1915,7 +1912,7 @@ png_init_read_transformations(png_structrp png_ptr)
            png_ptr->palette[i].blue = (png_byte)component;
         }
   }
-#endif /* READ_SHIFT */
+#endif  /* READ_SHIFT */
 }

 /* Modify the info structure to reflect the transformations.  The
--- a/pngtest.c
+++ b/pngtest.c
@@ -43,15 +43,6 @@

 #include "png.h"

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
 /* Known chunks that exist in pngtest.png must be supported or pngtest will fail
 * simply as a result of re-ordering them.  This may be fixed in 1.7
 *
@@ -2074,9 +2065,9 @@ main(void)
   fprintf(STDERR,
      " test ignored because libpng was not built with read support\n");
   /* And skip this test */
-   return SKIP;
+   return PNG_LIBPNG_VER < 10600 ? 0 : 77;
 }
 #endif

 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_22beta06 Your_png_h_is_not_version_1_6_22beta06;
+typedef png_libpng_version_1_6_21 Your_png_h_is_not_version_1_6_21;
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -12,9 +12,9 @@
 */

 #include "pngpriv.h"
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
+#if defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
 #  include <errno.h>
-#endif /* SIMPLIFIED_WRITE_STDIO */
+#endif

 #ifdef PNG_WRITE_SUPPORTED

@@ -1452,6 +1452,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,


 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+# ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
 /* Initialize the write structure - general purpose utility. */
 static int
 png_image_write_init(png_imagep image)
@@ -1503,10 +1504,6 @@ typedef struct
   png_const_voidp first_row;
   ptrdiff_t       row_bytes;
   png_voidp       local_row;
-   /* Byte count for memory writing */
-   png_bytep        memory;
-   png_alloc_size_t memory_bytes; /* not used for STDIO */
-   png_alloc_size_t output_bytes; /* running total */
 } png_image_write_control;

 /* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
@@ -1934,43 +1931,9 @@ png_image_write_main(png_voidp argument)
      png_set_benign_errors(png_ptr, 0/*error*/);
 #   endif

-   /* Default the 'row_stride' parameter if required, also check the row stride
-    * and total image size to ensure that they are within the system limits.
-    */
-   {
-      const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
-
-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
-      {
-         png_uint_32 check;
-         const png_uint_32 png_row_stride = image->width * channels;
-
-         if (display->row_stride == 0)
-            display->row_stride = (png_int_32)/*SAFE*/png_row_stride;
-
-         if (display->row_stride < 0)
-            check = -display->row_stride;
-
-         else
-            check = display->row_stride;
-
-         if (check >= png_row_stride)
-         {
-            /* Now check for overflow of the image buffer calculation; this
-             * limits the whole image size to 32 bits for API compatibility with
-             * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
-             */
-            if (image->height > 0xFFFFFFFF/png_row_stride)
-               png_error(image->opaque->png_ptr, "memory image too large");
-         }
-
-         else
-            png_error(image->opaque->png_ptr, "supplied row stride too small");
-      }
-
-      else
-         png_error(image->opaque->png_ptr, "image row stride too large");
-   }
+   /* Default the 'row_stride' parameter if required. */
+   if (display->row_stride == 0)
+      display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);

   /* Set the required transforms then write the rows in the correct order. */
   if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0)
@@ -2147,122 +2110,6 @@ png_image_write_main(png_voidp argument)
   return 1;
 }

-
-static void (PNGCBAPI
-image_memory_write)(png_structp png_ptr, png_bytep/*const*/ data,
-   png_size_t size)
-{
-   png_image_write_control *display = png_voidcast(png_image_write_control*,
-      png_ptr->io_ptr/*backdoor: png_get_io_ptr(png_ptr)*/);
-   const png_alloc_size_t ob = display->output_bytes;
-
-   /* Check for overflow; this should never happen: */
-   if (size <= ((png_alloc_size_t)-1) - ob)
-   {
-      /* I don't think libpng ever does this, but just in case: */
-      if (size > 0)
-      {
-         if (display->memory_bytes >= ob+size) /* writing */
-            memcpy(display->memory+ob, data, size);
-
-         /* Always update the size: */
-         display->output_bytes = ob+size;
-      }
-   }
-
-   else
-      png_error(png_ptr, "png_image_write_to_memory: PNG too big");
-}
-
-static void (PNGCBAPI
-image_memory_flush)(png_structp png_ptr)
-{
-   PNG_UNUSED(png_ptr)
-}
-
-static int
-png_image_write_memory(png_voidp argument)
-{
-   png_image_write_control *display = png_voidcast(png_image_write_control*,
-      argument);
-
-   /* The rest of the memory-specific init and write_main in an error protected
-    * environment.  This case needs to use callbacks for the write operations
-    * since libpng has no built in support for writing to memory.
-    */
-   png_set_write_fn(display->image->opaque->png_ptr, display/*io_ptr*/,
-         image_memory_write, image_memory_flush);
-
-   return png_image_write_main(display);
-}
-
-int PNGAPI
-png_image_write_to_memory(png_imagep image, void *memory,
-   png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8bit,
-   const void *buffer, png_int_32 row_stride, const void *colormap)
-{
-   /* Write the image to the given buffer, or count the bytes if it is NULL */
-   if (image != NULL && image->version == PNG_IMAGE_VERSION)
-   {
-      if (memory_bytes != NULL && buffer != NULL)
-      {
-         /* This is to give the caller an easier error detection in the NULL
-          * case and guard against uninitialized variable problems:
-          */
-         if (memory == NULL)
-            *memory_bytes = 0;
-
-         if (png_image_write_init(image) != 0)
-         {
-            png_image_write_control display;
-            int result;
-
-            memset(&display, 0, (sizeof display));
-            display.image = image;
-            display.buffer = buffer;
-            display.row_stride = row_stride;
-            display.colormap = colormap;
-            display.convert_to_8bit = convert_to_8bit;
-            display.memory = png_voidcast(png_bytep, memory);
-            display.memory_bytes = *memory_bytes;
-            display.output_bytes = 0;
-
-            result = png_safe_execute(image, png_image_write_memory, &display);
-            png_image_free(image);
-
-            /* write_memory returns true even if we ran out of buffer. */
-            if (result)
-            {
-               /* On out-of-buffer this function returns '0' but still updates
-                * memory_bytes:
-                */
-               if (memory != NULL && display.output_bytes > *memory_bytes)
-                  result = 0;
-
-               *memory_bytes = display.output_bytes;
-            }
-
-            return result;
-         }
-
-         else
-            return 0;
-      }
-
-      else
-         return png_image_error(image,
-            "png_image_write_to_memory: invalid argument");
-   }
-
-   else if (image != NULL)
-      return png_image_error(image,
-         "png_image_write_to_memory: incorrect PNG_IMAGE_VERSION");
-
-   else
-      return 0;
-}
-
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
 int PNGAPI
 png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
   const void *buffer, png_int_32 row_stride, const void *colormap)
@@ -2270,7 +2117,7 @@ png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
   /* Write the image to the given (FILE*). */
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
-      if (file != NULL && buffer != NULL)
+      if (file != NULL)
      {
         if (png_image_write_init(image) != 0)
         {
@@ -2320,7 +2167,7 @@ png_image_write_to_file(png_imagep image, const char *file_name,
   /* Write the image to the named file. */
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
-      if (file_name != NULL && buffer != NULL)
+      if (file_name != NULL)
      {
         FILE *fp = fopen(file_name, "wb");

@@ -2378,6 +2225,6 @@ png_image_write_to_file(png_imagep image, const char *file_name,
   else
      return 0;
 }
-#endif /* SIMPLIFIED_WRITE_STDIO */
+# endif /* STDIO */
 #endif /* SIMPLIFIED_WRITE */
 #endif /* WRITE */
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,7 +1,7 @@

 /* pngwutil.c - utilities to write a PNG file
 *
- * Last changed in libpng 1.6.22 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.21 [January 15, 2016]
 * Copyright (c) 1998-2002,2004,2006-2015 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.)
@@ -23,10 +23,10 @@
 void PNGAPI
 png_save_uint_32(png_bytep buf, png_uint_32 i)
 {
-   buf[0] = (png_byte)((i >> 24) & 0xffU);
-   buf[1] = (png_byte)((i >> 16) & 0xffU);
-   buf[2] = (png_byte)((i >>  8) & 0xffU);
-   buf[3] = (png_byte)( i        & 0xffU);
+   buf[0] = (png_byte)(i >> 24);
+   buf[1] = (png_byte)(i >> 16);
+   buf[2] = (png_byte)(i >> 8);
+   buf[3] = (png_byte)(i     );
 }

 /* Place a 16-bit number into a buffer in PNG byte order.
@@ -36,8 +36,8 @@ png_save_uint_32(png_bytep buf, png_uint_32 i)
 void PNGAPI
 png_save_uint_16(png_bytep buf, unsigned int i)
 {
-   buf[0] = (png_byte)((i >> 8) & 0xffU);
-   buf[1] = (png_byte)( i       & 0xffU);
+   buf[0] = (png_byte)(i >> 8);
+   buf[1] = (png_byte)(i     );
 }
 #endif

--- a/projects/vstudio/README.txt
+++ b/projects/vstudio/README.txt
@@ -1,7 +1,7 @@

 VisualStudio instructions

-libpng version 1.6.22beta06 - May 5, 2016
+libpng version 1.6.21 - January 15, 2016

 Copyright (c) 2010,2013,2015 Glenn Randers-Pehrson

--- a/projects/vstudio/zlib.props
+++ b/projects/vstudio/zlib.props
@@ -2,7 +2,7 @@
 <!--
 * zlib.props - location of zlib source
 *
- * libpng version 1.6.22beta06 - May 5, 2016
+ * libpng version 1.6.21 - January 15, 2016
 *
 * Copyright (c) 1998-2011 Glenn Randers-Pehrson
 *
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@

-Makefiles for  libpng version 1.6.22beta06 - May 5, 2016
+Makefiles for  libpng version 1.6.21 - January 15, 2016

 pnglibconf.h.prebuilt       =>  Stores configuration settings
 makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.22beta06)
+                       (gcc, creates libpng16.so.16.1.6.21)
 makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
 makefile.knr      =>  Archaic UNIX Makefile that converts files with
                       ansi2knr (Requires ansi2knr.c from
@@ -33,12 +33,12 @@ pnglibconf.h.prebuilt       =>  Stores configuration settings
 makefile.os2      =>  OS/2 Makefile (gcc and emx, requires libpng.def)
 makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
 makefile.sggcc    =>  Silicon Graphics (gcc,
-                       creates libpng16.so.16.1.6.22beta06)
+                       creates libpng16.so.16.1.6.21)
 makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
 makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.22beta06)
+                       creates libpng16.so.16.1.6.21)
 makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.22beta06)
+                       creates libpng16.so.16.1.6.21)
 makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
 makefile.sunos    =>  Sun makefile
 makefile.32sunu   =>  Sun Ultra 32-bit makefile
--- a/scripts/def.c
+++ b/scripts/def.c
@@ -21,7 +21,7 @@ PNG_DFN "OS2 DESCRIPTION "PNG image compression library""
 PNG_DFN "OS2 CODE PRELOAD MOVEABLE DISCARDABLE"
 PNG_DFN ""
 PNG_DFN "EXPORTS"
-PNG_DFN ";Version 1.6.22beta06"
+PNG_DFN ";Version 1.6.21"

 #define PNG_EXPORTA(ordinal, type, name, args, attributes)\
        PNG_DFN "@" SYMBOL_PREFIX "@@" name "@"
--- a/scripts/genchk.cmake.in
+++ b/scripts/genchk.cmake.in
@@ -1,37 +0,0 @@
-# genchk.cmake.in
-# Generate .chk from .out with awk (generic), based upon the automake logic.
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-# Variables substituted from CMakeLists.txt
-set(SRCDIR "@CMAKE_CURRENT_SOURCE_DIR@")
-
-set(AWK "@AWK@")
-
-get_filename_component(INPUTEXT "${INPUT}" EXT)
-get_filename_component(OUTPUTEXT "${OUTPUT}" EXT)
-get_filename_component(INPUTBASE "${INPUT}" NAME_WE)
-get_filename_component(OUTPUTBASE "${OUTPUT}" NAME_WE)
-get_filename_component(INPUTDIR "${INPUT}" PATH)
-get_filename_component(OUTPUTDIR "${OUTPUT}" PATH)
-
-if("${INPUTEXT}" STREQUAL ".out" AND "${OUTPUTEXT}" STREQUAL ".chk")
-  # Generate .chk from .out with awk (generic)
-  file(REMOVE "${OUTPUT}" "${OUTPUTDIR}/${OUTPUTBASE}.new")
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/checksym.awk"
-                          "${SRCDIR}/scripts/${INPUTBASE}.def"
-                          "of=${OUTPUTDIR}/${OUTPUTBASE}.new"
-                          "${INPUT}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate ${OUTPUTDIR}/${OUTPUTBASE}.new")
-  endif()
-  file(RENAME "${OUTPUTDIR}/${OUTPUTBASE}.new" "${OUTPUT}")
-else()
-  message(FATAL_ERROR "Unsupported conversion: ${INPUTEXT} to ${OUTPUTEXT}")
-endif()
--- a/scripts/genout.cmake.in
+++ b/scripts/genout.cmake.in
@@ -1,93 +0,0 @@
-# genout.cmake.in
-# Generate .out from .c with awk (generic), based upon the automake logic.
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-# Variables substituted from CMakeLists.txt
-set(SRCDIR "@CMAKE_CURRENT_SOURCE_DIR@")
-set(BINDIR "@CMAKE_CURRENT_BINARY_DIR@")
-
-set(AWK "@AWK@")
-set(CMAKE_C_COMPILER "@CMAKE_C_COMPILER@")
-set(CMAKE_C_FLAGS @CMAKE_C_FLAGS@)
-set(INCDIR "@CMAKE_CURRENT_BINARY_DIR@")
-set(PNG_PREFIX "@PNG_PREFIX@")
-set(PNGLIB_MAJOR "@PNGLIB_MAJOR@")
-set(PNGLIB_MINOR "@PNGLIB_MINOR@")
-set(PNGLIB_VERSION "@PNGLIB_VERSION@")
-set(ZLIBINCDIR "@ZLIB_INCLUDE_DIR@")
-
-set(PLATFORM_C_FLAGS)
-if(APPLE)
-  set(CMAKE_OSX_ARCHITECTURES "@CMAKE_OSX_ARCHITECTURES@")
-  set(CMAKE_OSX_SYSROOT "@CMAKE_OSX_SYSROOT@")
-  if(CMAKE_OSX_ARCHITECTURES)
-    set(PLATFORM_C_FLAGS ${PLATFORM_C_FLAGS} -arch ${CMAKE_OSX_ARCHITECTURES})
-  endif()
-  if(CMAKE_OSX_SYSROOT)
-    set(PLATFORM_C_FLAGS ${PLATFORM_C_FLAGS} -isysroot ${CMAKE_OSX_SYSROOT})
-  endif()
-endif()
-
-get_filename_component(INPUTEXT "${INPUT}" EXT)
-get_filename_component(OUTPUTEXT "${OUTPUT}" EXT)
-get_filename_component(INPUTBASE "${INPUT}" NAME_WE)
-get_filename_component(OUTPUTBASE "${OUTPUT}" NAME_WE)
-get_filename_component(INPUTDIR "${INPUT}" PATH)
-get_filename_component(OUTPUTDIR "${OUTPUT}" PATH)
-
-if ("${INPUTEXT}" STREQUAL ".c" AND "${OUTPUTEXT}" STREQUAL ".out")
-  get_filename_component(GENDIR "${OUTPUT}" PATH)
-  file(MAKE_DIRECTORY "${GENDIR}")
-
-  file(REMOVE "${OUTPUT}.tf1" "${OUTPUT}.tf2")
-
-  set(INCLUDES "-I${INCDIR}")
-  if(ZLIBINCDIR)
-    foreach(dir ${ZLIBINCDIR})
-      list(APPEND INCLUDES "-I${dir}")
-    endforeach()
-  endif()
-
-  if(PNG_PREFIX)
-    set(PNG_PREFIX_DEF "-DPNG_PREFIX=${PNG_PREFIX}")
-  endif()
-
-  execute_process(COMMAND "${CMAKE_C_COMPILER}" "-E"
-                          ${CMAKE_C_FLAGS}
-                          ${PLATFORM_C_FLAGS}
-                          "-I${SRCDIR}"
-                          "-I${BINDIR}"
-                          ${INCLUDES}
-                          "-DPNGLIB_LIBNAME=PNG${PNGLIB_MAJOR}${PNGLIB_MINOR}_0"
-                          "-DPNGLIB_VERSION=${PNGLIB_VERSION}"
-                          "-DSYMBOL_PREFIX=${SYMBOL_PREFIX}"
-                          "-DPNG_NO_USE_READ_MACROS"
-                          "-DPNG_BUILDING_SYMBOL_TABLE"
-                          ${PNG_PREFIX_DEF}
-                          "${INPUT}"
-                  OUTPUT_FILE "${OUTPUT}.tf1"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE CPP_FAIL)
-  if(CPP_FAIL)
-    message(FATAL_ERROR "Failed to generate ${OUTPUT}.tf1")
-  endif()
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/dfn.awk"
-                          "out=${OUTPUT}.tf2" "${OUTPUT}.tf1"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate ${OUTPUT}.tf2")
-  endif()
-
-  file(REMOVE "${OUTPUT}.tf1")
-  file(RENAME "${OUTPUT}.tf2" "${OUTPUT}")
-else()
-  message(FATAL_ERROR "Unsupported conversion: ${INPUTEXT} to ${OUTPUTEXT}")
-endif()
--- a/scripts/gensrc.cmake.in
+++ b/scripts/gensrc.cmake.in
@@ -1,138 +0,0 @@
-# gensrc.cmake.in
-# Generate source files with awk, based upon the automake logic.
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-# Variables substituted from CMakeLists.txt
-set(SRCDIR "@CMAKE_CURRENT_SOURCE_DIR@")
-set(BINDIR "@CMAKE_CURRENT_BINARY_DIR@")
-
-set(AWK "@AWK@")
-set(DFA_XTRA "@DFA_XTRA@")
-set(PNG_PREFIX "@PNG_PREFIX@")
-set(PNGLIB_VERSION "@PNGLIB_VERSION@")
-
-if("${OUTPUT}" STREQUAL "scripts/pnglibconf.c")
-  # Generate scripts/pnglibconf.c
-
-  file(REMOVE "${BINDIR}/pnglibconf.tf6" "${BINDIR}/pnglibconf.tf7")
-
-  execute_process(COMMAND "${CMAKE_COMMAND}" -E echo "com ${PNGLIB_VERSION} STANDARD API DEFINITION"
-                  COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                          "out=pnglibconf.tf6" "logunsupported=1" "version=search"
-                          "${SRCDIR}/pngconf.h" "-"
-                          "${SRCDIR}/scripts/pnglibconf.dfa"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf6")
-  endif()
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                  "out=pnglibconf.tf7" "pnglibconf.tf6"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf7")
-  endif()
-
-  file(REMOVE "pnglibconf.tf6")
-  file(MAKE_DIRECTORY "${BINDIR}/scripts")
-  file(RENAME "pnglibconf.tf7" "${BINDIR}/scripts/pnglibconf.c")
-
-elseif ("${OUTPUT}" STREQUAL "pnglibconf.c")
-  # Generate pnglibconf.c
-
-  file(REMOVE "${BINDIR}/pnglibconf.tf4" "${BINDIR}/pnglibconf.tf5")
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                  out=pnglibconf.tf4 version=search
-                  ${SRCDIR}/pngconf.h ${SRCDIR}/scripts/pnglibconf.dfa
-                  ${SRCDIR}/pngusr.dfa ${DFA_XTRA}
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf4")
-  endif()
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                  out=pnglibconf.tf5 pnglibconf.tf4
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf5")
-  endif()
-
-  file(REMOVE "pnglibconf.tf4")
-  file(MAKE_DIRECTORY "${BINDIR}/scripts")
-  file(RENAME "pnglibconf.tf5" "${BINDIR}/pnglibconf.c")
-
-elseif ("${OUTPUT}" STREQUAL "pnglibconf.h")
-  # Generate pnglibconf.h
-
-  file(REMOVE "${BINDIR}/${OUTPUT}")
-  if(PNG_PREFIX)
-    file(REMOVE "pnglibconf.tf8")
-
-    execute_process(COMMAND "${AWK}" "s==0 && NR>1{print prev}
-                             s==0{prev=\$0}
-                             s==1{print \"#define\", \$1, \"${PNG_PREFIX}\" \$1}
-                             s==2{print \"#define ${PNG_PREFIX}png_\" \$1, \"PNG_\" \$1}
-                             END{print prev}" s=0 pnglibconf.out s=1 "${BINDIR}/scripts/prefix.out"
-                             s=2 "${SRCDIR}/scripts/macro.lst"
-                    OUTPUT_FILE pnglibconf.tf8
-                    RESULT_VARIABLE AWK_FAIL)
-    if(AWK_FAIL)
-      message(FATAL_ERROR "Failed to generate pnglibconf.tf8")
-    endif()
-
-    file(RENAME "pnglibconf.tf8" "${BINDIR}/${OUTPUT}")
-  else()
-    execute_process(COMMAND "${CMAKE_COMMAND}" -E copy "${BINDIR}/pnglibconf.out"
-                                                       "${BINDIR}/${OUTPUT}"
-                    RESULT_VARIABLE COPY_FAIL)
-    if(COPY_FAIL)
-      message(FATAL_ERROR "Failed to create pnglibconf.h")
-    endif()
-  endif()
-
-elseif ("${OUTPUT}" STREQUAL "pngprefix.h")
-  # Generate pngprefix.h
-
-  file(REMOVE "${BINDIR}/${OUTPUT}")
-
-  if(PNG_PREFIX)
-    file(REMOVE "pngprefix.tf1")
-
-    execute_process(COMMAND "${AWK}"
-                            "{print \"#define\", \$1, \"${PNG_PREFIX}\" \$1}"
-                            "${BINDIR}/scripts/intprefix.out"
-                    OUTPUT_FILE "pngprefix.tf1"
-                    RESULT_VARIABLE AWK_FAIL)
-    if(AWK_FAIL)
-      message(FATAL_ERROR "Failed to generate pngprefix.tf1")
-    endif()
-
-    file(RENAME "pngprefix.tf1" "${BINDIR}/${OUTPUT}")
-  else()
-    file(WRITE "${BINDIR}/${OUTPUT}" "/* No libpng symbol prefix configured. */")
-  endif()
-
-elseif("${OUTPUT}" STREQUAL "scripts/pnglibconf.h.prebuilt")
-  # Generate scripts/pnglibconf.h.prebuilt (fails build)
-
-  message(STATUS "Attempting to build scripts/pnglibconf.h.prebuilt")
-  message(STATUS "This is a machine generated file, but if you want to make")
-  message(STATUS "a new one simply build the 'genfiles' target, and copy")
-  message(STATUS "scripts/pnglibconf.out to scripts/pnglibconf.h.prebuilt")
-  message(STATUS "AND set PNG_ZLIB_VERNUM to 0 (you MUST do this)")
-  message(FATAL_ERROR "Stopping build")
-
-else()
-  message(FATAL_ERROR "Unsupported output: ${OUTPUT}")
-endif()
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -11,7 +11,7 @@

 # Modeled after libxml-config.

-version=1.6.22beta06
+version=1.6.21
 prefix=""
 libdir=""
 libs=""
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@ includedir=@includedir@/libpng16

 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.22beta06
+Version: 1.6.21
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
--- a/scripts/makefile.cegcc
+++ b/scripts/makefile.cegcc
@@ -23,7 +23,7 @@

 VERMAJ = 1
 VERMIN = 6
-VERMIC = 22
+VERMIC = 21
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 22
+RELEASE = 21

 # Shared library names:
 LIBSO=$(LIBNAME).so
--- a/scripts/makefile.msys
+++ b/scripts/makefile.msys
@@ -18,7 +18,7 @@ exec_prefix=$(prefix)
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 22
+RELEASE = 21

 # Shared library names:
 LIBSO=$(LIBNAME).dll
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include/libpng16

 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.22beta06
+SHLIB_MINOR=	1.6.21
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include

 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.22beta06
+SHLIB_MINOR=	1.6.21
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -11,7 +11,7 @@ LIBDIR=	${PREFIX}/lib
 MANDIR= ${PREFIX}/man/cat

 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.22beta06
+SHLIB_MINOR=	1.6.21

 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \
--- a/scripts/pnglibconf.dfa
+++ b/scripts/pnglibconf.dfa
@@ -873,12 +873,9 @@ option SIMPLIFIED_READ_BGR enables FORMAT_BGR,

 # Write:
 option SIMPLIFIED_WRITE,
-   requires WRITE, SETJMP, WRITE_SWAP, WRITE_PACK,
+   requires WRITE STDIO, SETJMP, WRITE_SWAP, WRITE_PACK,
      WRITE_tRNS, WRITE_gAMA, WRITE_sRGB, WRITE_cHRM

-# 1.6.22: allow simplified write without stdio support:
-option SIMPLIFIED_WRITE_STDIO requires SIMPLIFIED_WRITE STDIO
-
 option SIMPLIFIED_WRITE_AFIRST enables FORMAT_AFIRST,
   requires SIMPLIFIED_WRITE WRITE_SWAP_ALPHA

--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,8 +1,8 @@
-/* libpng 1.6.22beta06 STANDARD API DEFINITION */
+/* libpng 1.6.21 STANDARD API DEFINITION */

 /* pnglibconf.h - library build configuration */

-/* Libpng version 1.6.22beta06 - May 5, 2016 */
+/* Libpng version 1.6.21 - January 15, 2016 */

 /* Copyright (c) 1998-2015 Glenn Randers-Pehrson */

@@ -109,7 +109,6 @@
 #define PNG_SIMPLIFIED_READ_SUPPORTED
 #define PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
 #define PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
-#define PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
 #define PNG_SIMPLIFIED_WRITE_SUPPORTED
 #define PNG_STDIO_SUPPORTED
 #define PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.22beta06
+;Version 1.6.21
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng
@@ -249,4 +249,3 @@ EXPORTS
 png_set_check_for_invalid_index @242
 png_get_palette_max @243
 png_set_option @244
- png_image_write_to_memory @245
--- a/scripts/test.cmake.in
+++ b/scripts/test.cmake.in
@@ -1,31 +0,0 @@
-# test.cmake.in
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-set(TEST_OPTIONS "@TEST_OPTIONS@")
-set(TEST_FILES "@TEST_FILES@")
-
-foreach(file ${TEST_FILES})
-  file(TO_NATIVE_PATH "${file}" native_file)
-  list(APPEND NATIVE_TEST_FILES "${native_file}")
-endforeach()
-
-# Add the directory containing libpng to the PATH (Windows only)
-if(WIN32)
-  get_filename_component(LIBPNG_DIR "${LIBPNG}" PATH)
-  file(TO_NATIVE_PATH "${LIBPNG_DIR}" LIBPNG_DIR)
-  set(ENV{PATH} "${LIBPNG_DIR};$ENV{PATH}")
-endif()
-
-execute_process(COMMAND "${CMAKE_COMMAND}" -E echo "Running ${TEST_COMMAND}" ${TEST_OPTIONS} ${NATIVE_TEST_FILES})
-
-execute_process(COMMAND "${TEST_COMMAND}" ${TEST_OPTIONS} ${NATIVE_TEST_FILES}
-                RESULT_VARIABLE TEST_STATUS)
-if(TEST_STATUS)
-  message(FATAL_ERROR "Returned failed status ${TEST_STATUS}!")
-endif()
--- a/tests/pngstest
+++ b/tests/pngstest
@@ -17,38 +17,36 @@ gamma="$1"
 shift
 alpha="$1"
 shift
-args=
-LC_ALL="C" # fix glob sort order to ASCII:
-for f in "${srcdir}/contrib/testpngs/"*.png
-do
-   g=
-   case "$f" in
-      *-linear[.-]*)
-         test "$gamma" = "linear" && g="$f";;
+exec ./pngstest --tmpfile "${gamma}-${alpha}-" --log ${1+"$@"} `
+   for f in "${srcdir}/contrib/testpngs/"*.png
+   do
+      g=
+      case "$f" in
+         *-linear[.-]*)
+            test "$gamma" = "linear" && g="$f";;

-      *-sRGB[.-]*)
-         test "$gamma" = "sRGB" && g="$f";;
+         *-sRGB[.-]*)
+            test "$gamma" = "sRGB" && g="$f";;

-      *-1.8[.-]*)
-         test "$gamma" = "1.8" && g="$f";;
+         *-1.8[.-]*)
+            test "$gamma" = "1.8" && g="$f";;

-      *)
-         test "$gamma" = "none" && g="$f";;
-   esac
+         *)
+            test "$gamma" = "none" && g="$f";;
+      esac

-   case "$g" in
-      "")
-         :;;
+      case "$g" in
+         "")
+            :;;

-      *-alpha[-.]*)
-         test "$alpha" = "alpha" && args="$args $g";;
+         *-alpha[-.]*)
+            test "$alpha" = "alpha" && echo "$g";;

-      *-tRNS[-.]*)
-         test "$alpha" = "tRNS" -o "$alpha" = "none" && args="$args $g";;
+         *-tRNS[-.]*)
+            test "$alpha" = "tRNS" -o "$alpha" = "none" && echo "$g";;

-      *)
-         test "$alpha" = "opaque" -o "$alpha" = "none" && args="$args $g";;
-   esac
-done
-# This only works if the arguments don't contain spaces; they don't.
-exec ./pngstest --tmpfile "${gamma}-${alpha}-" --log ${1+"$@"} $args
+         *)
+            test "$alpha" = "opaque" -o "$alpha" = "none" && echo "$g";;
+      esac
+   done
+`