riscv: Remove unused argument

Signed-off-by: Cosmin Truta <ctruta@gmail.com>

.appveyor.yml

@@ -0,0 +1,81 @@
+version: 1.6.x-{build}
+
+branches:
+  except:
+    - /libpng[0-1][0-8]/
+    - /v[0-1][.][0-8][.][0-9]+/
+
+image:
+  - Visual Studio 2022
+
+shallow_clone: true
+
+environment:
+  matrix:
+    - TOOLCHAIN: vstudio
+      AUTOMATION: cmake
+      ARCH: x86
+    - TOOLCHAIN: vstudio
+      AUTOMATION: cmake
+      ARCH: x64
+    - TOOLCHAIN: vstudio
+      AUTOMATION: cmake
+      ARCH: arm64
+    - TOOLCHAIN: llvm
+      AUTOMATION: cmake
+      ARCH: x64
+    - TOOLCHAIN: msys2
+      AUTOMATION: cmake
+      ARCH: i686
+    - TOOLCHAIN: msys2
+      AUTOMATION: cmake
+      ARCH: x86_64
+    - TOOLCHAIN: msys2
+      AUTOMATION: configure
+      ARCH: i686
+    - TOOLCHAIN: msys2
+      AUTOMATION: configure
+      ARCH: x86_64
+    - TOOLCHAIN: msys2
+      AUTOMATION: makefiles
+      ARCH: i686
+    - TOOLCHAIN: msys2
+      AUTOMATION: makefiles
+      ARCH: x86_64
+
+install:
+  - 'if "%TOOLCHAIN%"=="vstudio" C:\tools\vcpkg\vcpkg.exe install zlib:%ARCH%-windows'
+  - 'if "%TOOLCHAIN%"=="vstudio" C:\tools\vcpkg\vcpkg.exe integrate install'
+  - 'if "%TOOLCHAIN%"=="llvm" C:\tools\vcpkg\vcpkg.exe install zlib:%ARCH%-windows'
+  - 'if "%TOOLCHAIN%"=="llvm" C:\tools\vcpkg\vcpkg.exe integrate install'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="cmake" C:\msys64\usr\bin\pacman.exe -S --noconfirm mingw-w64-%ARCH%-cmake mingw-w64-%ARCH%-ninja'
+
+before_build:
+  - 'if "%TOOLCHAIN%"=="vstudio" set CI_CMAKE_GENERATOR=Visual Studio 17 2022'
+  - 'if "%TOOLCHAIN%"=="vstudio" set CI_CMAKE_TOOLCHAIN_FILE=C:\tools\vcpkg\scripts\buildsystems\vcpkg.cmake'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="x86" set CI_CMAKE_GENERATOR_PLATFORM=Win32'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="x64" set CI_CMAKE_GENERATOR_PLATFORM=x64'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="arm64" set CI_CMAKE_GENERATOR_PLATFORM=ARM64'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="arm64" set CI_CMAKE_VARS=-DPNG_TESTS=0'
+  - 'if "%TOOLCHAIN%"=="llvm" set CI_CMAKE_GENERATOR=Ninja'
+  - 'if "%TOOLCHAIN%"=="llvm" set CI_CMAKE_TOOLCHAIN_FILE=C:\tools\vcpkg\scripts\buildsystems\vcpkg.cmake'
+  - 'if "%TOOLCHAIN%"=="llvm" set CI_CC=clang'
+  - 'if "%TOOLCHAIN%"=="msys2" set CI_CMAKE_GENERATOR=Ninja'
+  - 'if "%TOOLCHAIN%"=="msys2" set CI_CC=gcc'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%ARCH%"=="i686" set MSYSTEM=MINGW32'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%ARCH%"=="x86_64" set MSYSTEM=MINGW64'
+  - 'set CI_CMAKE_BUILD_FLAGS=-j2'
+  - 'set CI_CTEST_FLAGS=-j2'
+  - 'set CI_MAKE_FLAGS=-j2'
+  - 'set CI_MAKEFILES=scripts/makefile.gcc scripts/makefile.msys scripts/makefile.std'
+
+build_script:
+  - 'if "%TOOLCHAIN%"=="vstudio" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_cmake.sh"'
+  - 'if "%TOOLCHAIN%"=="llvm" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_cmake.sh"'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="cmake" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_cmake.sh"'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="configure" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_configure.sh"'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="makefiles" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_makefiles.sh"'
+
+cache:
+  - 'C:\tools\vcpkg\installed'
+  - 'C:\msys64\var\cache\pacman'

.cmake-format.yaml

@@ -0,0 +1,94 @@
+# https://pypi.org/project/cmakelang
+# https://github.com/cheshirekow/cmake_format
+
+# ----------------------
+# Options for formatting
+# ----------------------
+
+# How wide to allow formatted cmake files
+# TODO: Reflow the CMake files to allow setting the maximum line width to 100.
+line_width: 255
+
+# How many spaces to tab for indent
+tab_size: 2
+
+# If true, lines are indented using tab characters (utf-8 0x09) instead of
+# <tab_size> space characters (utf-8 0x20). In cases where the layout would
+# require a fractional tab character, the behavior of the fractional
+# indentation is governed by <fractional_tab_policy>
+use_tabchars: false
+
+# If <use_tabchars> is True, then the value of this variable indicates how
+# fractional indentions are handled during whitespace replacement. If set to
+# 'use-space', fractional indentation is left as spaces (utf-8 0x20). If set
+# to `round-up` fractional indentation is replaced with a single tab character
+# (utf-8 0x09) effectively shifting the column to the next tabstop
+fractional_tab_policy: "use-space"
+
+# Enable comment markup parsing and reflow
+enable_markup: false
+
+# -------------------
+# Options for linting
+# -------------------
+
+# Lint codes to disable
+disabled_codes: [
+  # TODO:
+  # Reconcile the CMake variable names with the patterns below, then
+  # re-enable the "invalid variable name XXX" messages.
+  "C0103",
+
+  # TODO:
+  # Add brief COMMENT arguments to the `add_custom_target` commands.
+  "C0113",
+]
+
+# Regular expression pattern describing valid function names
+function_pattern: "[0-9a-z_]+"
+
+# Regular expression pattern describing valid macro names
+macro_pattern: "[0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for variables with global
+# (cache) scope
+global_var_pattern: "[A-Z][0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for variables with global
+# scope (but internal semantic)
+internal_var_pattern: "_[A-Z][0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for variables with local
+# scope
+local_var_pattern: "[a-z][a-z0-9_]+"
+
+# Regular expression pattern describing valid names for privatedirectory
+# variables
+private_var_pattern: "_[0-9a-z_]+"
+
+# Regular expression pattern describing valid names for public directory
+# variables
+public_var_pattern: "[A-Z][0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for function/macro
+# arguments and loop variables.
+argument_var_pattern: "[a-z][a-z0-9_]+"
+
+# Regular expression pattern describing valid names for keywords used in
+# functions or macros
+keyword_pattern: "[A-Z][0-9A-Z_]+"
+
+# In the heuristic for C0201, how many conditionals to match within a loop in
+# before considering the loop a parser
+max_conditionals_custom_parser: 2
+
+# Require at least this many newlines between statements;
+# require no more than this many newlines between statements;
+# etc.
+min_statement_spacing: 1
+max_statement_spacing: 2
+max_returns: 6
+max_branches: 12
+max_arguments: 5
+max_localvars: 15
+max_statements: 50

.editorconfig

@@ -0,0 +1,55 @@
+# https://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.txt]
+indent_size = unset
+indent_style = space
+
+[*.[chS]]
+indent_size = 3
+indent_style = space
+max_doc_length = 80
+max_line_length = 80
+
+[*.dfa]
+indent_size = 3
+indent_style = space
+max_doc_length = 80
+max_line_length = 80
+
+[*.awk]
+indent_size = 3
+indent_style = space
+max_doc_length = 80
+max_line_length = 100
+
+[*.cmake]
+indent_size = 2
+indent_style = space
+max_doc_length = 80
+max_line_length = 100
+
+[*.sh]
+indent_size = 4
+indent_style = space
+max_doc_length = 100
+max_line_length = 100
+
+[{Makefile.in,aclocal.m4,ltmain.sh}]
+indent_size = unset
+indent_style = unset
+insert_final_newline = unset
+max_doc_length = unset
+max_line_length = unset
+trim_trailing_whitespace = unset
+
+[COMMIT_EDITMSG]
+indent_style = space
+max_doc_length = unset
+max_line_length = 72

.editorconfig-checker.json

@@ -0,0 +1,9 @@
+{
+  "Disable": {
+    "IndentSize": true
+  },
+  "Exclude": [
+    ".git/",
+    "out/"
+  ]
+}

.github/workflows/lint.yml

@@ -0,0 +1,31 @@
+name: Linting libpng
+
+on:
+  push:
+    branches:
+      - libpng16
+      - libpng18
+  pull_request:
+    branches:
+      - libpng16
+      - libpng18
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Set up the cache
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pip
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/pip.txt') }}
+          restore-keys: ${{ runner.os }}-pip-
+      - name: Install yamllint
+        run: pip install yamllint
+      - name: Install editorconfig-checker
+        uses: editorconfig-checker/action-editorconfig-checker@main
+      - name: Check out the code
+        uses: actions/checkout@v4
+      - name: Run the linting script
+        run: bash ./ci/ci_lint.sh

.gitignore

@@ -0,0 +1,159 @@
+# Prerequisites
+*.d
+
+# Precompiled headers
+*.gch
+*.pch
+
+# Object files
+*.slo
+*.lo
+*.o
+*.obj
+
+# Linker output files
+*.exp
+*.ilk
+*.map
+
+# Compiled dynamic libraries
+*.dll
+*.dylib
+*.so
+*.so.*
+
+# Compiled static libraries
+*.a
+*.la
+*.lai
+*.lib
+
+# Compiled executables
+*.app/
+*.exe
+a.out
+
+# Debug files
+*.dSYM/
+*.idb
+*.pdb
+*.su
+
+# Tag files
+TAGS
+.TAGS
+!TAGS/
+tags
+.tags
+!tags/
+gtags.files
+GTAGS
+GRTAGS
+GPATH
+GSYMS
+cscope.files
+cscope.out
+cscope.*.out
+
+# Text editing and text processing artifacts
+\#*\#
+.\#*
+[._]*.sw[a-p]
+[._]sw[a-p]
+*.bak
+*.orig
+*.rej
+*.tmp
+*~
+
+# IDE files and directories
+## Eclipse
+.cproject/
+.project/
+.settings/
+## Embarcadero RAD Studio
+*.cbproj.*
+__recovery/
+## JetBrains
+.idea/
+## NetBeans
+nbbuild/
+nbdist/
+nbproject/
+## Visual Studio
+.vs/
+### Visual Studio user files
+*.rsuser
+*.sln.docstates
+*.suo
+*.user
+*.userprefs
+### Visual Studio cache files (for older versions)
+*.aps
+*.ncb
+*.opensdf
+*.sdf
+*.VC.db
+*.VC.opendb
+ipch/
+## Visual Studio Code
+.vscode/*
+!.vscode/extensions.json
+!.vscode/launch.json
+!.vscode/settings.json
+!.vscode/tasks.json
+## (Various)
+*.*cache
+*.cache*
+[._]*_history
+.history/
+[Bb]ackup*/
+
+# Build, test and CI output directories
+*[Dd]ebug/
+[Dd]ebug*/
+*[Rr]elease/
+[Rr]elease*/
+[._]build*/
+/[Bb]uild*/
+/[Oo]ut/
+
+# Libpng configuration and auxiliary build artifacts
+*.out
+*out.png
+[._]deps/
+[._]libs/
+.dirstamp
+/Makefile
+/autom4te.cache/
+/config*~
+/config.h
+/config.log
+/config.status
+/install*~
+/libpng*-config
+/libpng*.pc
+/libpng.vers
+/libtool
+/stamp-h1
+CMake*.json
+!CMakePresets.json
+CMakeLists.txt.*
+pnglibconf.[ch]
+pnglibconf.dfn
+pnglibconf.pre
+pngprefix.h
+
+# Libpng test programs, scripts and artifacts
+/test-suite.log
+/tests/*.log
+/tests/*.trs
+/png-fix-itxt
+/pngcp
+/pngfix
+/pngimage
+/pngstest
+/pngtest
+/pngunknown
+/pngvalid
+/timepng

.yamllint.yml

@@ -0,0 +1,7 @@
+extends: default
+rules:
+  document-start: disable
+  document-end: disable
+  line-length: disable
+  truthy:
+    check-keys: false

ANNOUNCE

@@ -1,22 +1,48 @@
+libpng 1.6.50.git
+=================
 
-Libpng 1.0.12beta1 - May 14, 2001
+This is a development version, not intended to be a public release.
+It will be replaced by a public release, or by another development
+version, at a later time.
 
-This is a public release of libpng, intended for use in production codes.
 
-Changes since the last public release (1.0.11):
+libpng 1.6.49 - June 12, 2025
+=============================
 
-  Test for Windows platform in pngconf.h when including malloc.h (Emmanuel Blot)
-  Updated makefile.cygwin and handling of Cygwin's ALL_STATIC in pngconf.h
-  Added some never-to-be-executed code in pnggccrd.c to quiet compiler warnings.
-  Bumped DLLNUM to 2.
-  Added a check for attempts to read or write PLTE in grayscale PNG datastreams.
-  Eliminated the png_error about apps using png_read|write_init().  Instead,
-    libpng will reallocate the png_struct and info_struct if they are too small.
-    This achieves future binary compatibility for old applications written for
-    libpng-0.88 and earlier.
-  Modified png_create_struct so it passes user mem_ptr to user memory allocator.
+This is a public release of libpng, intended for use in production code.
 
-Send comments/corrections/commendations to
-png-implement@ccrc.wustl.edu or to randeg@alum.rpi.edu
 
-Glenn R-P
+Files available for download
+----------------------------
+
+Source files with LF line endings (for Unix/Linux):
+
+ * libpng-1.6.49.tar.xz (LZMA-compressed, recommended)
+ * libpng-1.6.49.tar.gz (deflate-compressed)
+
+Source files with CRLF line endings (for Windows):
+
+ * lpng1649.7z (LZMA-compressed, recommended)
+ * lpng1649.zip (deflate-compressed)
+
+Other information:
+
+ * README.md
+ * LICENSE.md
+ * AUTHORS.md
+ * TRADEMARK.md
+
+
+Changes from version 1.6.48 to version 1.6.49
+---------------------------------------------
+
+ * Added SIMD-optimized code for the RISC-V Vector Extension (RVV).
+   (Contributed by Manfred Schlaegl, Dragos Tiselice and Filip Wasil)
+ * Added various fixes and improvements to the build scripts and to
+   the sample code.
+
+
+Send comments/corrections/commendations to png-mng-implement at lists.sf.net.
+Subscription is required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe.

AUTHORS

@@ -0,0 +1,66 @@
+PNG REFERENCE LIBRARY AUTHORS
+=============================
+
+This is the list of PNG Reference Library ("libpng") Contributing
+Authors, for copyright and licensing purposes.
+
+ * Adam Richter
+ * Andreas Dilger
+ * Chris Blume
+ * Cosmin Truta
+ * Dave Martindale
+ * Eric S. Raymond
+ * Gilles Vollant
+ * Glenn Randers-Pehrson
+ * Greg Roelofs
+ * Guy Eric Schalnat
+ * James Yu
+ * John Bowler
+ * Kevin Bracey
+ * Lucas Chollet
+ * Magnus Holmgren
+ * Mandar Sahastrabuddhe
+ * Manfred Schlaegl
+ * Mans Rullgard
+ * Matt Sarett
+ * Mike Klein
+ * Pascal Massimino
+ * Paul Schmidt
+ * Philippe Antoine
+ * Qiang Zhou
+ * Sam Bushell
+ * Samuel Williams
+ * Simon-Pierre Cadieux
+ * Tim Wegner
+ * Tom Lane
+ * Tom Tanner
+ * Vadim Barkov
+ * Willem van Schaik
+ * Zhijie Liang
+ * Apple Inc.
+    - Zixu Wang (王子旭)
+ * Arm Holdings
+    - Richard Townsend
+ * Google LLC
+    - Dan Field
+    - Dragoș Tiselice
+    - Leon Scroggins III
+    - Matt Sarett
+    - Mike Klein
+    - Sami Boukortt
+    - Wan-Teh Chang
+ * Loongson Technology Corporation Ltd.
+    - GuXiWei (顾希伟)
+    - JinBo (金波)
+    - ZhangLixia (张利霞)
+ * Samsung Group
+    - Filip Wasil
+
+The build projects, the build scripts, the test scripts, and other
+files in the "projects", "scripts" and "tests" directories, have
+other copyright owners, but are released under the libpng license.
+
+Some files in the "ci" and "contrib" directories, as well as some
+of the tools-generated files that are distributed with libpng, have
+other copyright owners, and are released under other open source
+licenses.

INSTALL

@@ -1,137 +1,467 @@
+    Installing libpng
 
-Installing libpng version 1.0.12beta1 - May 14, 2001
+Contents
 
-Before installing libpng, you must first install zlib.  zlib
-can usually be found wherever you got libpng.  zlib can be
-placed in another directory, at the same level as libpng.
-Note that your system might already have a preinstalled
-zlib, but you will still need to have access to the
-zlib.h and zconf.h include files that correspond to the
-version of zlib that's installed.
+       I. Simple installation
+      II. Rebuilding the configure scripts
+     III. Using scripts/makefile*
+      IV. Using cmake
+       V. Directory structure
+      VI. Building with project files
+     VII. Building with makefiles
+    VIII. Configuring libpng for 16-bit platforms
+      IX. Configuring for DOS
+       X. Configuring for Medium Model
+      XI. Prepending a prefix to exported symbols
+     XII. Configuring for compiler xxx:
+    XIII. Removing unwanted object code
+     XIV. Enabling or disabling hardware optimizations
+      XV. Changes to the build and configuration of libpng in libpng-1.5.x
+     XVI. Setjmp/longjmp issues
+    XVII. Common linking failures
+   XVIII. Other sources of information about libpng
+
+I. Simple installation
+
+On Unix/Linux and similar systems, you can simply type
+
+    ./configure [--prefix=/path]
+    make check
+    make install
+
+and ignore the rest of this document.  "/path" is the path to the directory
+where you want to install the libpng "lib", "include", and "bin"
+subdirectories.
+
+If you downloaded a GIT clone, you will need to run ./autogen.sh before
+running ./configure, to create "configure" and "Makefile.in" which are
+not included in the GIT repository.
+
+Note that "configure" is only included in the "*.tar" distributions and not
+in the "*.zip" or "*.7z" distributions. If you downloaded one of those
+distributions, see "Building with project files" or "Building with makefiles",
+below.
+
+II. Rebuilding the configure scripts
+
+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:
+
+    ./configure --enable-maintainer-mode
+    make maintainer-clean
+    ./autogen.sh --maintainer --clean
+    ./autogen.sh --maintainer
+    ./configure [--prefix=/path] [other options]
+    make
+    make install
+    make check
+
+III. Using scripts/makefile*
+
+Instead, you can use one of the custom-built makefiles in the
+"scripts" directory
+
+    cp scripts/pnglibconf.h.prebuilt pnglibconf.h
+    cp scripts/makefile.system makefile
+    make test
+    make install
+
+The files that are presently available in the scripts directory
+are listed and described in scripts/README.txt.
+
+Or you can use one of the "projects" in the "projects" directory.
+
+Before installing libpng, you must first install zlib, if it
+is not already on your system.  zlib can usually be found
+wherever you got libpng; otherwise go to https://zlib.net/.  You can
+place zlib in the same directory as libpng or in another directory.
+
+If your system already has a preinstalled zlib you will still need
+to have access to the zlib.h and zconf.h include files that
+correspond to the version of zlib that's installed.
+
+If you wish to test with a particular zlib that is not first in the
+standard library search path, put ZLIBLIB, ZLIBINC, CPPFLAGS, LDFLAGS,
+and LD_LIBRARY_PATH in your environment before running "make test"
+or "make distcheck":
+
+    ZLIBLIB=/path/to/lib export ZLIBLIB
+    ZLIBINC=/path/to/include export ZLIBINC
+    CPPFLAGS="-I$ZLIBINC" export CPPFLAGS
+    LDFLAGS="-L$ZLIBLIB" export LDFLAGS
+    LD_LIBRARY_PATH="$ZLIBLIB:$LD_LIBRARY_PATH" export LD_LIBRARY_PATH
+
+If you are using one of the makefile scripts, put ZLIBLIB and ZLIBINC
+in your environment and type
+
+    make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test
+
+IV. Using cmake
+
+If you want to use "cmake" (see www.cmake.org), type
+
+    cmake . -DCMAKE_INSTALL_PREFIX=/path
+    make
+    make install
+
+As when using the simple configure method described above, "/path" points to
+the installation directory where you want to put the libpng "lib", "include",
+and "bin" subdirectories.
+
+V. Directory structure
 
 You can rename the directories that you downloaded (they
-might be called "libpng-1.0.12beta1" or "lpng109" and "zlib-1.1.3"
-or "zlib113") so that you have directories called "zlib" and "libpng".
+might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.8"
+or "zlib128") so that you have directories called "zlib" and "libpng".
 
 Your directory structure should look like this:
 
-   ..       (the parent directory)
-      libpng  (this directory)
+    .. (the parent directory)
+      libpng (this directory)
           INSTALL (this file)
           README
-          *.h
-          *.c
+          *.h, *.c  => libpng source files
+          CMakeLists.txt    =>  "cmake" script
+          ci
+             ci_*.sh
+          configuration files:
+             configure.ac, configure, Makefile.am, Makefile.in,
+             autogen.sh, config.guess, ltmain.sh, missing, libpng.pc.in,
+             libpng-config.in, aclocal.m4, config.h.in, config.sub,
+             depcomp, install-sh, mkinstalldirs, test-pngtest.sh, etc.
           contrib
-             gregbook
-             msvctest
-             pngminus
-             pngsuite
-             visupng
+             arm-neon, conftest, examples, gregbook, libtests, pngminim,
+             pngminus, pngsuite, tools, visupng, riscv-rvv
           projects
-             beos
-             borland
-             msvc
-             wince
+             owatcom, visualc71, vstudio
           scripts
              makefile.*
+             *.def (module definition files)
+             etc.
           pngtest.png
           etc.
       zlib
-          README
-          *.h
-          *.c
-          contrib
-          etc.
+          README, *.h, *.c, contrib, etc.
 
 If the line endings in the files look funny, you may wish to get the other
 distribution of libpng.  It is available in both tar.gz (UNIX style line
 endings) and zip (DOS style line endings) formats.
 
-If you are building libpng with MSVC, you can enter the libpng\msvc directory
-and follow the instructions in msvc\README.txt.  You can build libpng for
-WindowsCE by entering the libpng\wince directory and following the
-instructions in the README* files.
+VI. Building with project files
 
-Else enter the zlib directory and follow the instructions in zlib/README,
-then come back here and choose the appropriate makefile.sys in the scripts
-directory.
+If you are building libpng with Microsoft Visual Studio, you can enter
+the directory projects\visualc71 or projects\vstudio and follow the
+instructions in README.txt.
 
-The files that are presently available in the scripts directory
-include
+Otherwise, enter the zlib directory and follow the instructions in
+zlib/README, then come back here and run "configure" or choose the
+appropriate makefile in the scripts directory.
 
- makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
- makefile.linux    =>  Linux/ELF makefile (gcc, creates libpng.so.2.1.0.12beta1)
- makefile.gcmmx    =>  Linux/ELF makefile (gcc, creates libpng.so.2.1.0.12beta1,
-                       uses assembler code tuned for Intel MMX platform)
- makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
- makefile.knr      =>  Archaic UNIX Makefile that converts files with
-                       ansi2knr (Requires ansi2knr.c from
-                       ftp://ftp.cs.wisc.edu/ghost)
- makefile.aix      =>  AIX makefile
- makefile.cygwin   =>  Cygwin/gcc makefile
- makefile.dec      =>  DEC Alpha UNIX makefile
- makefile.hpgcc    =>  HPUX makefile using gcc
- makefile.hpux     =>  HPUX (10.20 and 11.00) makefile
- makefile.ibmc     =>  IBM C/C++ version 3.x for Win32 and OS/2 (static)
- makefile.intel    =>  Intel C/C++ version 4.0 and later
- libpng.icc        =>  Project file for IBM VisualAge/C++ version 4.0 or later
- makefile.macosx   =>  MACOS X Makefile
- makefile.netbsd   =>  NetBSD/cc makefile, uses PNGGCCRD
- makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
- makefile.sggcc    =>  Silicon Graphics (gcc, creates libpng.so.2.1.0.12beta1)
- makefile.sunos    =>  Sun makefile
- makefile.solaris  =>  Solaris 2.X makefile (gcc, creates libpng.so.2.1.0.12beta1)
- makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
- makefile.mips     =>  MIPS makefile
- makefile.acorn    =>  Acorn makefile
- makefile.amiga    =>  Amiga makefile
- smakefile.ppc     =>  AMIGA smakefile for SAS C V6.58/7.00 PPC compiler
-                       (Requires SCOPTIONS, copied from scripts/SCOPTIONS.ppc)
- makefile.atari    =>  Atari makefile
- makefile.beos     =>  BEOS makefile for X86
- makefile.bor      =>  Borland makefile (uses bcc)
- makefile.bc32     =>  32-bit Borland C++ (all modules compiled in C mode)
- makefile.bd32     =>  To make a png32bd.dll with Borland C++ 4.5
- makefile.tc3      =>  Turbo C 3.0 makefile
- makefile.dj2      =>  DJGPP 2 makefile
- makefile.msc      =>  Microsoft C makefile
- makefile.vcawin32 =>  makefile for Microsoft Visual C++ 5.0 and later (uses
-                       assembler code tuned for Intel MMX platform)
- makefile.vcwin32  =>  makefile for Microsoft Visual C++ 4.0 and later (does
-                       not use assembler code)
- makefile.os2      =>  OS/2 Makefile (gcc and emx, requires pngos2.def)
- pngos2.def        =>  OS/2 module definition file used by makefile.os2
- makefile.watcom   =>  Watcom 10a+ Makefile, 32-bit flat memory model
- makevms.com       =>  VMS build script
- descrip.mms       =>  VMS makefile for MMS or MMK
- pngdef.pas        =>  Defines for a png32bd.dll with Borland C++ 4.5
- SCOPTIONS.ppc     =>  Used with smakefile.ppc
+VII. Building with makefiles
 
 Copy the file (or files) that you need from the
 scripts directory into this directory, for example
 
-   MSDOS example: copy scripts\makefile.msc makefile
-   UNIX example:    cp scripts/makefile.std makefile
+UNIX example:
+
+    cp scripts/makefile.std Makefile
+    make
+
+Windows example:
+
+    nmake -f scripts\makefile.vcwin32
 
 Read the makefile to see if you need to change any source or
 target directories to match your preferences.
 
-Then read pngconf.h to see if you want to make any configuration
+Then read pnglibconf.dfa to see if you want to make any configuration
 changes.
 
-Then just run "make test" which will create the libpng library in
-this directory and run a quick test that reads the "pngtest.png"
-file and writes a "pngout.png" file that should be identical to it.
-Look for "9782 zero samples" in the output of the test.  For more
-confidence, you can run another test by typing "pngtest pngnow.png"
-and looking for "289 zero samples" in the output.  Also, you can
-run "pngtest -m *.png" in the "contrib/pngsuite" directory and compare
+Then just run "make" which will create the libpng library in
+this directory and "make test" which will run a quick test that reads
+the "pngtest.png" file and writes a "pngout.png" file that should be
+identical to it.  Look for "9782 zero samples" in the output of the
+test.  For more confidence, you can run another test by typing
+"pngtest pngnow.png" and looking for "289 zero samples" in the output.
+Also, you can run "pngtest -m contrib/pngsuite/*.png" and compare
 your output with the result shown in contrib/pngsuite/README.
 
-Most of the makefiles will allow you to run "make install" to
-put the library in its final resting place (if you want to
-do that, run "make install" in the zlib directory first if necessary).
+Most of the makefiles used to allow you to run "make install" to put
+the library in its final resting place, but that feature is no longer
+supported.  The only tested and supported manners to install libpng are
+the conventional build and install procedures driven by the configure
+script or by the CMake file.
 
-Further information can be found in the README and libpng.txt
-files, in the individual makefiles, in png.h, in the README files in
-subdirectories of the LIB directory, and the manual pages libpng.3 and png.5.
+VIII. Configuring for DOS and other 16-bit platforms
+
+Officially, the support for 16-bit platforms has been removed.
+
+For DOS users who only have access to the lower 640K, you will
+have to limit zlib's memory usage via a png_set_compression_mem_level()
+call.  See zlib.h or zconf.h in the zlib library for more information.
+
+You may be or may not be in luck if you target the "large" memory model,
+but all the smaller models ("small", "compact" and "medium") are known
+to be unworkable.  For DOS users who have access beyond the lower 640K,
+a "flat" 32-bit DOS model (such as DJGPP) is strongly recommended.
+
+For DOS users who only have access to the lower 640K, you will have to
+limit zlib's memory usage via a png_set_compression_mem_level() call.
+You will also have to look into zconf.h to tell zlib (and thus libpng)
+that it cannot allocate more than 64K at a time.  Even if you can, the
+memory won't be accessible.  Therefore, you should limit zlib and libpng
+to 64K by defining MAXSEG_64K.
+
+IX. Prepending a prefix to exported symbols
+
+Starting with libpng-1.6.0, you can configure libpng (when using the
+"configure" script) to prefix all exported symbols by means of the
+configuration option "--with-libpng-prefix=FOO_", where FOO_ can be any
+string beginning with a letter and containing only uppercase
+and lowercase letters, digits, and the underscore (i.e., a C language
+identifier).  This creates a set of macros in pnglibconf.h, so this is
+transparent to applications; their function calls get transformed by
+the macros to use the modified names.
+
+X. Configuring for compiler xxx:
+
+All includes for libpng are in pngconf.h.  If you need to add, change
+or delete an include, this is the place to do it.
+The includes that are not needed outside libpng are placed in pngpriv.h,
+which is only used by the routines inside libpng itself.
+The files in libpng proper only include pngpriv.h and png.h, which
+in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h.
+As of libpng-1.5.0, pngpriv.h also includes three other private header
+files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
+that previously appeared in the public headers.
+
+XI. Removing unwanted object code
+
+There are a bunch of #define's in pngconf.h that control what parts of
+libpng are compiled.  All the defines end in _SUPPORTED.  If you are
+never going to use a capability, you can change the #define to #undef
+before recompiling libpng and save yourself code and data space, or
+you can turn off individual capabilities with defines that begin with
+"PNG_NO_".
+
+In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
+
+You can also turn all of the transforms and ancillary chunk capabilities
+off en masse with compiler directives that define
+PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
+or all four, along with directives to turn on any of the capabilities that
+you do want.  The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the
+extra transformations but still leave the library fully capable of reading
+and writing PNG files with all known public chunks. Use of the
+PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
+that is incapable of reading or writing ancillary chunks.  If you are
+not using the progressive reading capability, you can turn that off
+with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
+capability, which you'll still have).
+
+All the reading and writing specific code are in separate files, so the
+linker should only grab the files it needs.  However, if you want to
+make sure, or if you are building a stand alone library, all the
+reading files start with "pngr" and all the writing files start with "pngw".
+The files that don't match either (like png.c, pngtrans.c, etc.)
+are used for both reading and writing, and always need to be included.
+The progressive reader is in pngpread.c
+
+If you are creating or distributing a dynamically linked library (a .so
+or DLL file), you should not remove or disable any parts of the library,
+as this will cause applications linked with different versions of the
+library to fail if they call functions not available in your library.
+The size of the library itself should not be an issue, because only
+those sections that are actually used will be loaded into memory.
+
+XII. Enabling or disabling hardware optimizations
+
+Certain hardware capabilities, such as the Intel SSE instructions,
+are normally detected at run time. Enable them with configure options
+such as one of
+
+   --enable-arm-neon=yes
+   --enable-mips-msa=yes
+   --enable-intel-sse=yes
+   --enable-powerpc-vsx=yes
+   --enable-riscv-rvv=yes
+
+or enable them all at once with
+
+   --enable-hardware-optimizations=yes
+
+or, if you are not using "configure", you can use one
+or more of
+
+   CPPFLAGS += "-DPNG_ARM_NEON"
+   CPPFLAGS += "-DPNG_MIPS_MSA"
+   CPPFLAGS += "-DPNG_INTEL_SSE"
+   CPPFLAGS += "-DPNG_POWERPC_VSX"
+   CPPFLAGS += "-DPNG_RISCV_RVV"
+
+See for example scripts/makefile.linux-opt
+
+If you wish to avoid using them,
+you can disable them via the configure option
+
+   --disable-hardware-optimizations
+
+to disable them all, or
+
+   --enable-intel-sse=no
+
+to disable a particular one,
+or via compiler-command options such as
+
+   CPPFLAGS += "-DPNG_ARM_NEON_OPT=0, -DPNG_MIPS_MSA_OPT=0,
+   -DPNG_INTEL_SSE_OPT=0, -DPNG_POWERPC_VSX_OPT=0,
+   -DPNG_RISCV_RVV_OPT=0"
+
+If you are using cmake, hardware optimizations are "on"
+by default. To disable them, use
+
+    cmake . -DPNG_ARM_NEON=no -DPNG_INTEL_SSE=no \
+            -DPNG_MIPS_MSA=no -DPNG_POWERPC_VSX=no \
+            -DPNG_RISCV_RVV=no
+
+or disable them all at once with
+
+    cmake . -DPNG_HARDWARE_OPTIMIZATIONS=no
+
+XIII. Changes to the build and configuration of libpng in libpng-1.5.x
+
+Details of internal changes to the library code can be found in the CHANGES
+file and in the GIT repository logs.  These will be of no concern to the vast
+majority of library users or builders; however, the few who configure libpng
+to a non-default feature set may need to change how this is done.
+
+There should be no need for library builders to alter build scripts if
+these use the distributed build support - configure or the makefiles -
+however, users of the makefiles may care to update their build scripts
+to build pnglibconf.h where the corresponding makefile does not do so.
+
+Building libpng with a non-default configuration has changed completely.
+The old method using pngusr.h should still work correctly even though the
+way pngusr.h is used in the build has been changed; however, library
+builders will probably want to examine the changes to take advantage of
+new capabilities and to simplify their build system.
+
+A. Specific changes to library configuration capabilities
+
+The exact mechanism used to control attributes of API functions has
+changed.  A single set of operating system independent macro definitions
+is used and operating system specific directives are defined in
+pnglibconf.h
+
+As part of this the mechanism used to choose procedure call standards on
+those systems that allow a choice has been changed.  At present this only
+affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
+running on Intel processors.  As before, PNGAPI is defined where required
+to control the exported API functions; however, two new macros, PNGCBAPI
+and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
+(PNGCAPI) for functions that must match a C library prototype (currently
+only png_longjmp_ptr, which must match the C longjmp function.)  The new
+approach is documented in pngconf.h
+
+Despite these changes, libpng 1.5.0 only supports the native C function
+calling standard on those platforms tested so far ("__cdecl" on Microsoft
+Windows).  This is because the support requirements for alternative
+calling conventions seem to no longer exist.  Developers who find it
+necessary to set PNG_API_RULE to 1 should advise the mailing list
+(png-mng-implement) of this and library builders who use Openwatcom and
+therefore set PNG_API_RULE to 2 should also contact the mailing list.
+
+B. Changes to the configuration mechanism
+
+Prior to libpng-1.5.0 library builders who needed to configure libpng
+had either to modify the exported pngconf.h header file to add system
+specific configuration or had to write feature selection macros into
+pngusr.h and cause this to be included into pngconf.h by defining
+PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
+application built without PNG_USER_CONFIG defined would see the
+unmodified, default, libpng API and thus would probably fail to link.
+
+These mechanisms still work in the configure build and in any makefile
+build that builds pnglibconf.h, although the feature selection macros
+have changed somewhat as described above.  In 1.5.0, however, pngusr.h is
+processed only once, at the time the exported header file pnglibconf.h is
+built.  pngconf.h no longer includes pngusr.h; therefore, pngusr.h is ignored
+after the build of pnglibconf.h and it is never included in an application
+build.
+
+The formerly used alternative of adding a list of feature macros to the
+CPPFLAGS setting in the build also still works; however, the macros will be
+copied to pnglibconf.h and this may produce macro redefinition warnings
+when the individual C files are compiled.
+
+All configuration now only works if pnglibconf.h is built from
+scripts/pnglibconf.dfa.  This requires the program awk.  Brian Kernighan
+(the original author of awk) maintains C source code of that awk and this
+and all known later implementations (often called by subtly different
+names - nawk and gawk for example) are adequate to build pnglibconf.h.
+The Sun Microsystems (now Oracle) program 'awk' is an earlier version
+and does not work; this may also apply to other systems that have a
+functioning awk called 'nawk'.
+
+Configuration options are now documented in scripts/pnglibconf.dfa.  This
+file also includes dependency information that ensures a configuration is
+consistent; that is, if a feature is switched off, dependent features are
+also switched off.  As a recommended alternative to using feature macros in
+pngusr.h a system builder may also define equivalent options in pngusr.dfa
+(or, indeed, any file) and add that to the configuration by setting
+DFA_XTRA to the file name.  The makefiles in contrib/pngminim illustrate
+how to do this, and also illustrate a case where pngusr.h is still required.
+
+After you have built libpng, the definitions that were recorded in
+pnglibconf.h are available to your application (pnglibconf.h is included
+in png.h and gets installed alongside png.h and pngconf.h in your
+$PREFIX/include directory).  Do not edit pnglibconf.h after you have built
+libpng, because than the settings would not accurately reflect the settings
+that were used to build libpng.
+
+XIV. Setjmp/longjmp issues
+
+Libpng uses setjmp()/longjmp() for error handling.  Unfortunately setjmp()
+is known to be not thread-safe on some platforms and we don't know of
+any platform where it is guaranteed to be thread-safe.  Therefore, if
+your application is going to be using multiple threads, you should
+configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
+-DPNG_NO_SETJMP on your compile line, or with
+
+    #undef PNG_SETJMP_SUPPORTED
+
+in your pnglibconf.h or pngusr.h.
+
+Starting with libpng-1.6.0, the library included a "simplified API".
+This requires setjmp/longjmp, so you must either build the library
+with PNG_SETJMP_SUPPORTED defined, or with PNG_SIMPLIFIED_READ_SUPPORTED
+and PNG_SIMPLIFIED_WRITE_SUPPORTED undefined.
+
+XV. Common linking failures
+
+If your application fails to find libpng or zlib entries while linking:
+
+  Be sure "-lz" appears after "-lpng" on your linking command.
+
+  Be sure you have built libpng, zlib, and your application for the
+  same platform (e.g., 32-bit or 64-bit).
+
+  If you are using the vstudio project, observe the WARNING in
+  project/vstudio/README.txt.
+
+XVI. Other sources of information about libpng:
+
+Further information can be found in the README and libpng-manual.txt
+files, in the individual makefiles, in png.h, and the manual pages
+libpng.3 and png.5.
+
+Copyright (c) 2022 Cosmin Truta
+Copyright (c) 1998-2002,2006-2016 Glenn Randers-Pehrson
+This document is released under the libpng license.
+For conditions of distribution and use, see the disclaimer
+and license in png.h.

KNOWNBUG

@@ -1,7 +0,0 @@
-
-Known bugs in libpng-1.0.11
-
-1. April 22, 2001: pnggccrd.c has been reported to crash on NetBSD when
-   reading interlaced PNG files, when assembler code is enabled.
-
-   STATUS: Under investigation.

LICENSE

@@ -1,102 +1,134 @@
+COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
+=========================================
 
-This copy of the libpng notices is provided for your convenience.  In case of
-any discrepancy between this copy and the notices in the file png.h that is
-included in the libpng distribution, the latter shall prevail.
+PNG Reference Library License version 2
+---------------------------------------
 
-COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+ * Copyright (c) 1995-2025 The PNG Reference Library Authors.
+ * Copyright (c) 2018-2025 Cosmin Truta.
+ * Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson.
+ * Copyright (c) 1996-1997 Andreas Dilger.
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 
-If you modify libpng you may insert additional notices immediately following
-this sentence.
+The software is supplied "as is", without warranty of any kind,
+express or implied, including, without limitation, the warranties
+of merchantability, fitness for a particular purpose, title, and
+non-infringement.  In no event shall the Copyright owners, or
+anyone distributing the software, be liable for any damages or
+other liability, whether in contract, tort or otherwise, arising
+from, out of, or in connection with the software, or the use or
+other dealings in the software, even if advised of the possibility
+of such damage.
 
-libpng versions 1.0.7, July 1, 2000, through 1.0.12beta1, May 14, 2001, are
-Copyright (c) 2000, 2001 Glenn Randers-Pehrson
-and are distributed according to the same disclaimer and license as libpng-1.0.6
-with the following individuals added to the list of Contributing Authors
+Permission is hereby granted to use, copy, modify, and distribute
+this software, or portions hereof, for any purpose, without fee,
+subject to the following restrictions:
 
-   Simon-Pierre Cadieux
-   Eric S. Raymond
-   Gilles Vollant
+ 1. The origin of this software must not be misrepresented; you
+    must not claim that you wrote the original software.  If you
+    use this software in a product, an acknowledgment in the product
+    documentation would be appreciated, but is not required.
+
+ 2. Altered source versions must be plainly marked as such, and must
+    not be misrepresented as being the original software.
+
+ 3. This Copyright notice may not be removed or altered from any
+    source or altered source distribution.
+
+
+PNG Reference Library License version 1 (for libpng 0.5 through 1.6.35)
+-----------------------------------------------------------------------
+
+libpng versions 1.0.7, July 1, 2000, through 1.6.35, July 15, 2018 are
+Copyright (c) 2000-2002, 2004, 2006-2018 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
+added to the list of Contributing Authors:
+
+    Simon-Pierre Cadieux
+    Eric S. Raymond
+    Mans Rullgard
+    Cosmin Truta
+    Gilles Vollant
+    James Yu
+    Mandar Sahastrabuddhe
+    Google Inc.
+    Vadim Barkov
 
 and with the following additions to the disclaimer:
 
-   There is no warranty against interference with your enjoyment of the
-   library or against infringement.  There is no warranty that our
-   efforts or the library will fulfill any of your particular purposes
-   or needs.  This library is provided with all faults, and the entire
-   risk of satisfactory quality, performance, accuracy, and effort is with
-   the user.
+    There is no warranty against interference with your enjoyment of
+    the library or against infringement.  There is no warranty that our
+    efforts or the library will fulfill any of your particular purposes
+    or needs.  This library is provided with all faults, and the entire
+    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, 1999 Glenn Randers-Pehrson, and are
-distributed according to the same disclaimer and license as libpng-0.96,
-with the following individuals added to the list of Contributing Authors:
+Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+libpng-0.96, and are distributed according to the same disclaimer and
+license as libpng-0.96, with the following individuals added to the
+list of Contributing Authors:
 
-   Tom Lane
-   Glenn Randers-Pehrson
-   Willem van Schaik
+    Tom Lane
+    Glenn Randers-Pehrson
+    Willem van Schaik
 
 libpng versions 0.89, June 1996, through 0.96, May 1997, are
-Copyright (c) 1996, 1997 Andreas Dilger
-Distributed according to the same disclaimer and license as libpng-0.88,
-with the following individuals added to the list of Contributing Authors:
+Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+and are distributed according to the same disclaimer and license as
+libpng-0.88, with the following individuals added to the list of
+Contributing Authors:
 
-   John Bowler
-   Kevin Bracey
-   Sam Bushell
-   Magnus Holmgren
-   Greg Roelofs
-   Tom Tanner
+    John Bowler
+    Kevin Bracey
+    Sam Bushell
+    Magnus Holmgren
+    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.
+Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 
 For the purposes of this copyright and license, "Contributing Authors"
 is defined as the following set of individuals:
 
-   Andreas Dilger
-   Dave Martindale
-   Guy Eric Schalnat
-   Paul Schmidt
-   Tim Wegner
+    Andreas Dilger
+    Dave Martindale
+    Guy Eric Schalnat
+    Paul Schmidt
+    Tim Wegner
 
-The PNG Reference Library is supplied "AS IS".  The Contributing Authors
-and Group 42, Inc. disclaim all warranties, expressed or implied,
-including, without limitation, the warranties of merchantability and of
-fitness for any purpose.  The Contributing Authors and Group 42, Inc.
-assume no liability for direct, indirect, incidental, special, exemplary,
-or consequential damages, which may result from the use of the PNG
-Reference Library, even if advised of the possibility of such damage.
+The PNG Reference Library is supplied "AS IS".  The Contributing
+Authors and Group 42, Inc. disclaim all warranties, expressed or
+implied, including, without limitation, the warranties of
+merchantability and of fitness for any purpose.  The Contributing
+Authors and Group 42, Inc. assume no liability for direct, indirect,
+incidental, special, exemplary, or consequential damages, which may
+result from the use of the PNG Reference Library, even if advised of
+the possibility of such damage.
 
 Permission is hereby granted to use, copy, modify, and distribute this
 source code, or portions hereof, for any purpose, without fee, subject
 to the following restrictions:
 
-1. The origin of this source code must not be misrepresented.
+ 1. The origin of this source code must not be misrepresented.
 
-2. Altered versions must be plainly marked as such and
-   must not be misrepresented as being the original source.
+ 2. Altered versions must be plainly marked as such and must not
+    be misrepresented as being the original source.
 
-3. This Copyright notice may not be removed or altered from
-   any source or altered source distribution.
+ 3. This Copyright notice may not be removed or altered from any
+    source or altered source distribution.
 
-The Contributing Authors and Group 42, Inc. specifically permit, without
-fee, and encourage the use of this source code as a component to
-supporting the PNG file format in commercial products.  If you use this
-source code in a product, acknowledgment is not required but would be
-appreciated.
-
-
-A "png_get_copyright" function is available, for convenient use in "about"
-boxes and the like:
-
-   printf("%s",png_get_copyright(NULL));
-
-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.
-
-Glenn Randers-Pehrson
-randeg@alum.rpi.edu
-May 14, 2001
+The Contributing Authors and Group 42, Inc. specifically permit,
+without fee, and encourage the use of this source code as a component
+to supporting the PNG file format in commercial products.  If you use
+this source code in a product, acknowledgment is not required but would
+be appreciated.

Makefile.am

@@ -0,0 +1,437 @@
+# Makefile.am, the source file for Makefile.in (and hence Makefile), is
+#
+# Copyright (c) 2018-2025 Cosmin Truta
+# Copyright (c) 2004-2016 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
+
+PNGLIB_BASENAME= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
+
+ACLOCAL_AMFLAGS = -I scripts/autoconf
+
+# test programs - run on make check, make distcheck
+if ENABLE_TESTS
+check_PROGRAMS= pngtest pngunknown pngstest pngvalid pngimage pngcp
+if HAVE_CLOCK_GETTIME
+check_PROGRAMS += timepng
+endif
+else
+check_PROGRAMS=
+endif
+
+# Utilities - installed
+if ENABLE_TOOLS
+bin_PROGRAMS= pngfix png-fix-itxt
+else
+bin_PROGRAMS=
+endif
+
+# This ensures that pnglibconf.h gets built at the start of 'make all' or
+# 'make check', but it does not add dependencies to the individual programs,
+# this is done below.
+#
+# IMPORTANT: always add the object modules of new programs to the list below
+# because otherwise the sequence 'configure; make new-program' will *sometimes*
+# result in the installed (system) pnglibconf.h being used and the result is
+# always wrong and always very confusing.
+BUILT_SOURCES = pnglibconf.h
+
+if ENABLE_TESTS
+pngtest_SOURCES = pngtest.c
+pngtest_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngvalid_SOURCES = contrib/libtests/pngvalid.c
+pngvalid_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngstest_SOURCES = contrib/libtests/pngstest.c
+pngstest_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngunknown_SOURCES = contrib/libtests/pngunknown.c
+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
+
+pngcp_SOURCES = contrib/tools/pngcp.c
+pngcp_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+endif
+
+if ENABLE_TOOLS
+pngfix_SOURCES = contrib/tools/pngfix.c
+pngfix_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+png_fix_itxt_SOURCES = contrib/tools/png-fix-itxt.c
+endif
+
+# Generally these are single line shell scripts to run a test with a particular
+# set of parameters:
+if ENABLE_TESTS
+TESTS =\
+   tests/pngtest-all\
+   tests/pngvalid-gamma-16-to-8 tests/pngvalid-gamma-alpha-mode\
+   tests/pngvalid-gamma-background tests/pngvalid-gamma-expand16-alpha-mode\
+   tests/pngvalid-gamma-expand16-background\
+   tests/pngvalid-gamma-expand16-transform tests/pngvalid-gamma-sbit\
+   tests/pngvalid-gamma-threshold tests/pngvalid-gamma-transform\
+   tests/pngvalid-progressive-size\
+   tests/pngvalid-progressive-interlace-standard\
+   tests/pngvalid-transform\
+   tests/pngvalid-progressive-standard tests/pngvalid-standard\
+   tests/pngstest-1.8 tests/pngstest-1.8-alpha tests/pngstest-linear\
+   tests/pngstest-linear-alpha tests/pngstest-none tests/pngstest-none-alpha\
+   tests/pngstest-sRGB tests/pngstest-sRGB-alpha tests/pngunknown-IDAT\
+   tests/pngunknown-discard tests/pngunknown-if-safe tests/pngunknown-sAPI\
+   tests/pngunknown-sTER tests/pngunknown-save tests/pngunknown-vpAg\
+   tests/pngimage-quick tests/pngimage-full
+endif
+
+# man pages
+dist_man_MANS= libpng.3 libpngpf.3 png.5
+
+# generate the -config scripts if required
+binconfigs= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config
+EXTRA_SCRIPTS= libpng-config libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config
+bin_SCRIPTS= @binconfigs@
+
+# rules to build libpng, only build the old library on request
+lib_LTLIBRARIES=libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+# EXTRA_LTLIBRARIES= libpng.la
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\
+	pngget.c pngmem.c pngpread.c pngread.c pngrio.c pngrtran.c pngrutil.c\
+	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_intrinsics.c \
+	arm/palette_neon_intrinsics.c
+endif
+
+if PNG_MIPS_MSA
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c\
+	mips/filter_msa_intrinsics.c
+endif
+
+if PNG_MIPS_MMI
+if !PNG_MIPS_MSA
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c
+endif
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/filter_mmi_inline_assembly.c
+endif
+
+if PNG_INTEL_SSE
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += intel/intel_init.c\
+	intel/filter_sse2_intrinsics.c
+endif
+
+if PNG_POWERPC_VSX
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += powerpc/powerpc_init.c\
+        powerpc/filter_vsx_intrinsics.c
+endif
+
+if PNG_RISCV_RVV
+noinst_LTLIBRARIES= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv.la
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv_la_SOURCES = riscv/riscv_init.c\
+        riscv/filter_rvv_intrinsics.c
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv_la_CFLAGS = -march=rv64gv
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LIBADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv.la
+endif
+
+if PNG_LOONGARCH_LSX
+noinst_LTLIBRARIES= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx.la
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx_la_SOURCES = loongarch/loongarch_lsx_init.c\
+	loongarch/filter_lsx_intrinsics.c
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx_la_CFLAGS = -mlsx
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LIBADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx.la
+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
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS += -Wl,-M -Wl,libpng.vers
+else
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS += -Wl,--version-script=libpng.vers
+endif
+
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES = libpng.vers
+else
+#   Only restricted exports when possible
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS += -export-symbols libpng.sym
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES = libpng.sym
+endif
+
+if PNG_RISCV_RVV
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES += libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv.la
+endif
+
+if PNG_LOONGARCH_LSX
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES += libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx.la
+endif
+
+#distribute headers in /usr/include/libpng/*
+pkgincludedir= $(includedir)/$(PNGLIB_BASENAME)
+pkginclude_HEADERS= png.h pngconf.h
+nodist_pkginclude_HEADERS= pnglibconf.h
+
+# pkg-config stuff, note that libpng.pc is always required in order
+# to get the correct library
+pkgconfigdir = @pkgconfigdir@
+pkgconfig_DATA = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc
+
+# Extra source distribution files, '${srcdir}' is used below to stop build files
+# from those directories being included.  This only works if the configure is
+# not done in the source directory!
+EXTRA_DIST= \
+	ANNOUNCE AUTHORS CHANGES INSTALL LICENSE README TODO TRADEMARK \
+	pngtest.png pngbar.png pngnow.png pngbar.jpg autogen.sh \
+	${srcdir}/ci ${srcdir}/contrib ${srcdir}/projects ${srcdir}/scripts \
+	$(TESTS) $(XFAIL_TESTS) tests/pngstest \
+	CMakeLists.txt example.c libpng-manual.txt
+
+SCRIPT_CLEANFILES=scripts/*.out scripts/*.chk
+
+CLEANFILES= *.tf? pngout.png libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc \
+	libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config libpng.vers libpng.sym \
+	check.new pnglibconf.h pngprefix.h symbols.new pngtest-log.txt \
+	pnglibconf.out pnglibconf.c pnglibconf.pre pnglibconf.dfn \
+	$(SCRIPT_CLEANFILES)
+
+MAINTAINERCLEANFILES = Makefile.in aclocal.m4 config.guess config.h.in \
+config.sub configure depcomp install-sh ltmain.sh missing
+
+# PNG_COPTS give extra options for the C compiler to be used on all compilation
+# steps (unless target_CFLAGS is specified; that will take precedence over
+# AM_CFLAGS)
+PNG_COPTS = @PNG_COPTS@
+AM_CFLAGS = ${PNG_COPTS}
+
+# DFNCPP is normally just CPP - the C preprocessor - but on Solaris and maybe
+# other operating systems (NeXT?) the C preprocessor selected by configure
+# checks input tokens for validity - effectively it performs part of the ANSI-C
+# parsing - and therefore fails with the .df files.  configure.ac has special
+# checks for this and sets DFNCPP appropriately.
+DFNCPP = @DFNCPP@
+
+SUFFIXES = .chk .out
+
+$(PNGLIB_BASENAME).pc: libpng.pc
+	cp libpng.pc $@
+
+$(PNGLIB_BASENAME)-config: libpng-config
+	cp libpng-config $@
+
+scripts/sym.out scripts/vers.out: png.h pngconf.h pnglibconf.h
+scripts/prefix.out: png.h pngconf.h pnglibconf.out
+scripts/symbols.out: png.h pngconf.h $(srcdir)/scripts/pnglibconf.h.prebuilt
+scripts/intprefix.out: pnglibconf.h
+
+libpng.sym: scripts/sym.out
+	rm -f $@
+	cp $? $@
+libpng.vers: scripts/vers.out
+	rm -f $@
+	cp $? $@
+
+if DO_PNG_PREFIX
+# Rename functions in scripts/prefix.out with a PNG_PREFIX prefix.
+# Rename macros in scripts/macro.lst from PNG_PREFIXpng_ to PNG_ (the actual
+# implementation of the macro).
+pnglibconf.h: pnglibconf.out scripts/prefix.out scripts/macro.lst
+	rm -f $@
+	$(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_" $$1}\
+	   END{print prev}' s=0 pnglibconf.out s=1 scripts/prefix.out\
+	   s=2 ${srcdir}/scripts/macro.lst >pnglibconf.tf8
+	mv pnglibconf.tf8 $@
+
+pngprefix.h: scripts/intprefix.out
+	rm -f pngprefix.tf1
+	$(AWK) '{print "#define", $$1, "@PNG_PREFIX@" $$1}' $? >pngprefix.tf1
+	mv pngprefix.tf1 $@
+else
+pnglibconf.h: pnglibconf.out
+	rm -f $@
+	cp $? $@
+
+pngprefix.h: # is empty
+	:>$@
+endif
+
+$(srcdir)/scripts/pnglibconf.h.prebuilt:
+	@echo "Attempting to build $@" >&2
+	@echo "This is a machine generated file, but if you want to make" >&2
+	@echo "a new one simply make 'scripts/pnglibconf.out', copy that" >&2
+	@echo "AND set PNG_ZLIB_VERNUM to 0 (you MUST do this)" >&2
+	@exit 1
+
+# The following is necessary to ensure that the local pnglibconf.h is used, not
+# an installed one (this can happen immediately after on a clean system if
+# 'make test' is the first thing the user does.)  Only files which include
+# one of the png source files (typically png.h or pngpriv.h) need to be listed
+# here:
+pngtest.o: pnglibconf.h
+
+contrib/libtests/makepng.o: pnglibconf.h
+contrib/libtests/pngstest.o: pnglibconf.h
+contrib/libtests/pngunknown.o: pnglibconf.h
+contrib/libtests/pngimage.o: pnglibconf.h
+contrib/libtests/pngvalid.o: pnglibconf.h
+contrib/libtests/readpng.o: pnglibconf.h
+contrib/libtests/tarith.o: pnglibconf.h
+contrib/libtests/timepng.o: pnglibconf.h
+
+contrib/tools/makesRGB.o: pnglibconf.h
+contrib/tools/pngfix.o: pnglibconf.h
+contrib/tools/pngcp.o: pnglibconf.h
+
+# We must use -DPNG_NO_USE_READ_MACROS here even when the library may actually
+# be built with PNG_USE_READ_MACROS; this prevents the read macros from
+# interfering with the symbol file format.
+SYMBOL_CFLAGS = -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
+
+if DO_PNG_PREFIX
+SYMBOL_CFLAGS += -DPNG_PREFIX='@PNG_PREFIX@'
+endif
+
+.c.out:
+	rm -f $@ $*.tf[12]
+	test -d scripts || mkdir scripts || test -d scripts
+	$(DFNCPP) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES)\
+	    $(CPPFLAGS) $(SYMBOL_CFLAGS) $< > $*.tf1
+	$(AWK) -f "${srcdir}/scripts/dfn.awk" out="$*.tf2" $*.tf1 1>&2
+	rm -f $*.tf1
+	mv $*.tf2 $@
+
+# The .c file for pnglibconf.h is machine generated
+pnglibconf.c: scripts/pnglibconf.dfa scripts/options.awk pngconf.h pngusr.dfa $(DFA_XTRA)
+	rm -f $@ $*.tf[45]
+	$(AWK) -f ${srcdir}/scripts/options.awk out=$*.tf4 version=search\
+	    ${srcdir}/pngconf.h ${srcdir}/scripts/pnglibconf.dfa\
+	    ${srcdir}/pngusr.dfa $(DFA_XTRA) 1>&2
+	$(AWK) -f ${srcdir}/scripts/options.awk out=$*.tf5 $*.tf4 1>&2
+	rm $*.tf4
+	mv $*.tf5 $@
+
+# Symbol checks (.def and .out files should match)
+scripts/symbols.chk: scripts/checksym.awk scripts/symbols.def scripts/symbols.out
+
+.out.chk:
+	rm -f $@ $*.new
+	$(AWK) -f ${srcdir}/scripts/checksym.awk ${srcdir}/scripts/${*F}.def\
+	    of="$*.new" $< >&2
+	mv $*.new $@
+
+# used on demand to regenerate the standard header, CPPFLAGS should
+# be empty - no non-standard defines
+scripts/pnglibconf.c: scripts/pnglibconf.dfa scripts/options.awk pngconf.h
+	rm -f $@ pnglibconf.tf[67]
+	test -z "$(CPPFLAGS)"
+	echo "com @PNGLIB_VERSION@ STANDARD API DEFINITION" |\
+	$(AWK) -f ${srcdir}/scripts/options.awk out=pnglibconf.tf6\
+	    logunsupported=1 version=search ${srcdir}/pngconf.h -\
+	    ${srcdir}/scripts/pnglibconf.dfa 1>&2
+	$(AWK) -f ${srcdir}/scripts/options.awk out=pnglibconf.tf7\
+	    pnglibconf.tf6 1>&2
+	rm pnglibconf.tf6
+	mv pnglibconf.tf7 $@
+
+$(libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_OBJECTS): png.h pngconf.h \
+	pnglibconf.h pngpriv.h pngdebug.h pnginfo.h pngstruct.h pngprefix.h
+
+test: check-am
+
+# Extra checks
+check: scripts/symbols.chk
+
+# Don't distribute the generated script files
+dist-hook:
+	cd '$(top_distdir)'; rm -f $(SCRIPT_CLEANFILES)
+
+# Make links between installed files with release-specific names and the generic
+# file names.  If this install rule is run the generic names will be deleted and
+# recreated - this has obvious issues for systems with multiple installations.
+
+install-header-links:
+	@set -ex; cd '$(DESTDIR)$(includedir)'; for f in $(HEADERS); do \
+	   rm -f "$$f"; $(LN_S) "$(PNGLIB_BASENAME)/$$f" "$$f"; done
+
+uninstall-header-links:
+	cd '$(DESTDIR)$(includedir)'; rm -f $(HEADERS)
+
+install-libpng-pc:
+	@set -ex; cd '$(DESTDIR)$(pkgconfigdir)'; rm -f libpng.pc; \
+	   $(LN_S) '$(PNGLIB_BASENAME).pc' libpng.pc
+
+uninstall-libpng-pc:
+	rm -f '$(DESTDIR)$(pkgconfigdir)/libpng.pc'
+
+# EXT_LIST is a list of the possibly library directory extensions, this exists
+# because we can't find a good way of discovering the file extensions that are
+# actually installed on a given system, so instead we check for every extension
+# we have seen.
+
+EXT_LIST = a dll.a so so.@PNGLIB_MAJOR@@PNGLIB_MINOR@.@PNGLIB_RELEASE@ la sl dylib
+
+install-library-links:
+	@set -x; cd '$(DESTDIR)$(libdir)';\
+	for ext in $(EXT_LIST); do\
+	   rm -f "libpng.$$ext";\
+           if test -f "$(PNGLIB_BASENAME).$$ext"; then\
+              $(LN_S) "$(PNGLIB_BASENAME).$$ext" "libpng.$$ext" || exit 1;\
+           fi;\
+	done
+
+uninstall-library-links:
+	@set -x; cd '$(DESTDIR)$(libdir)'; for ext in $(EXT_LIST); do\
+	   rm -f "libpng.$$ext"; done
+
+install-libpng-config:
+	@set -ex; cd '$(DESTDIR)$(bindir)'; rm -f libpng-config; \
+	   $(LN_S) '$(PNGLIB_BASENAME)-config' libpng-config
+
+uninstall-libpng-config:
+	rm -f '$(DESTDIR)$(bindir)/libpng-config'
+
+if DO_INSTALL_LINKS
+# If --enable-unversioned-links is specified the header and lib file links
+# will be automatically made on a 'make install':
+
+install-data-hook: install-header-links
+uninstall-hook: uninstall-header-links
+install-exec-hook: install-library-links
+uninstall-hook: uninstall-library-links
+endif
+
+if DO_INSTALL_LIBPNG_PC
+# Likewise, --install-pc causes libpng.pc to be constructed:
+
+install-data-hook: install-libpng-pc
+uninstall-hook: uninstall-libpng-pc
+endif
+
+if DO_INSTALL_LIBPNG_CONFIG
+# And --install-config:
+
+install-exec-hook: install-libpng-config
+uninstall-hook: uninstall-libpng-config
+endif
+
+# The following addition ensures that 'make all' always builds the test programs
+# too.  It used to, but some change either in libpng or configure stopped this
+# working.
+all-am: $(check_PROGRAMS)

README

@@ -1,49 +1,88 @@
-README for libpng 1.0.12beta1 - May 14, 2001 (shared library 2.1)
-See the note about version numbers near the top of png.h
+README for libpng version 1.6.50.git
+====================================
 
-See INSTALL for instructions on how to install libpng.
+See the note about version numbers near the top of `png.h`.
+See `INSTALL` for instructions on how to install libpng.
 
-Libpng comes in two distribution formats.  Get libpng-*.tar.gz if you
-want UNIX-style line endings in the text files, or lpng*.zip if you want
-DOS-style line endings.
+Libpng comes in several distribution formats.  Get `libpng-*.tar.gz`
+or `libpng-*.tar.xz` if you want UNIX-style line endings in the text
+files, or `lpng*.7z` or `lpng*.zip` if you want DOS-style line endings.
 
-Version 0.89 was the first official release of libpng.  Don't let the
-fact that it's the first release fool you.  The libpng library has been in
-extensive use and testing since mid-1995.  By late 1997 it had
-finally gotten to the stage where there hadn't been significant
-changes to the API in some time, and people have a bad feeling about
-libraries with versions < 1.0.  Version 1.0.0 was released in
-March 1998.
+For a detailed description on using libpng, read `libpng-manual.txt`.
+For examples of libpng in a program, see `example.c` and `pngtest.c`.
+For usage information and restrictions (what little they are) on libpng,
+see `png.h`.  For a description on using zlib (the compression library
+used by libpng) and zlib's restrictions, see `zlib.h`.
 
-****
-Note that some of the changes to the png_info structure render this
+You should use zlib 1.0.4 or later to run this, but it _may_ work with
+versions as old as zlib 0.95.  Even so, there are bugs in older zlib
+versions which can cause the output of invalid compression streams for
+some images.
+
+You should also note that zlib is a compression library that is useful
+for more things than just PNG files.  You can use zlib as a drop-in
+replacement for `fread()` and `fwrite()`, if you are so inclined.
+
+zlib should be available at the same place that libpng is, or at
+https://zlib.net .
+
+You may also want a copy of the PNG specification.  It is available
+as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
+these at http://www.libpng.org/pub/png/pngdocs.html .
+
+This code is currently being archived at https://libpng.sourceforge.io
+in the download area, and at http://libpng.download/src .
+
+This release, based in a large way on Glenn's, Guy's and Andreas'
+earlier work, was created and will be supported by myself and the PNG
+development group.
+
+Send comments, corrections and commendations to `png-mng-implement`
+at `lists.sourceforge.net`.  (Subscription is required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe.)
+
+Send general questions about the PNG specification to `png-mng-misc`
+at `lists.sourceforge.net`.  (Subscription is required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-misc
+to subscribe.)
+
+Historical notes
+----------------
+
+The libpng library has been in extensive use and testing since mid-1995.
+Version 0.89, published a year later, was the first official release.
+By late 1997, it had finally gotten to the stage where there hadn't
+been significant changes to the API in some time, and people have a bad
+feeling about libraries with versions below 1.0.  Version 1.0.0 was
+released in March 1998.
+
+Note that some of the changes to the `png_info` structure render this
 version of the library binary incompatible with libpng-0.89 or
 earlier versions if you are using a shared library.  The type of the
-"filler" parameter for png_set_filler() has changed from png_byte to
-png_uint_32, which will affect shared-library applications that use
-this function.
+`filler` parameter for `png_set_filler()` has changed from `png_byte`
+to `png_uint_32`, which will affect shared-library applications that
+use this function.
 
-To avoid problems with changes to the internals of png_info_struct,
+To avoid problems with changes to the internals of the `info_struct`,
 new APIs have been made available in 0.95 to avoid direct application
-access to info_ptr.  These functions are the png_set_<chunk> and
-png_get_<chunk> functions.  These functions should be used when
-accessing/storing the info_struct data, rather than manipulating it
+access to `info_ptr`.  These functions are the `png_set_<chunk>` and
+`png_get_<chunk>` functions.  These functions should be used when
+accessing/storing the `info_struct` data, rather than manipulating it
 directly, to avoid such problems in the future.
 
-It is important to note that the APIs do not make current programs
+It is important to note that the APIs did not make current programs
 that access the info struct directly incompatible with the new
-library.  However, it is strongly suggested that new programs use
-the new APIs (as shown in example.c and pngtest.c), and older programs
-be converted to the new format, to facilitate upgrades in the future.
-****
-
-Additions since 0.90 include the ability to compile libpng as a
-Windows DLL, and new APIs for accessing data in the info struct.
-Experimental functions include the ability to set weighting and cost
-factors for row filter selection, direct reads of integers from buffers
-on big-endian processors that support misaligned data access, faster
-methods of doing alpha composition, and more accurate 16->8 bit color
-conversion.
+library, through libpng-1.2.x.  In libpng-1.4.x, which was meant to
+be a transitional release, members of the `png_struct` and the
+`info_struct` can still be accessed, but the compiler will issue a
+warning about deprecated usage.  Since libpng-1.5.0, direct access
+to these structs is not allowed, and the definitions of the structs
+reside in private `pngstruct.h` and `pnginfo.h` header files that are
+not accessible to applications.  It is strongly suggested that new
+programs use the new APIs (as shown in `example.c` and `pngtest.c`),
+and older programs be converted to the new format, to facilitate
+upgrades in the future.
 
 The additions since 0.89 include the ability to read from a PNG stream
 which has had some (or all) of the signature bytes read by the calling
@@ -53,195 +92,93 @@ the library action on the detection of chunk CRC errors.  It is possible
 to set different actions based on whether the CRC error occurred in a
 critical or an ancillary chunk.
 
-The changes made to the library, and bugs fixed are based on discussions
-on the PNG implementation mailing list <png-implement@ccrc.wustl.edu>
-and not on material submitted privately to Guy, Andreas, or Glenn.  They will
-forward any good suggestions to the list.
+The additions since 0.90 include the ability to compile libpng as a
+Windows DLL, and new APIs for accessing data in the `info_struct`.
+Experimental functions included the ability to set weighting and cost
+factors for row filter selection, direct reads of integers from buffers
+on big-endian processors that support misaligned data access, faster
+methods of doing alpha composition, and more accurate 16-to-8 bit color
+conversion.  Some of these experimental functions, such as the weighted
+filter heuristics, have since been removed.
 
-For a detailed description on using libpng, read libpng.txt.  For
-examples of libpng in a program, see example.c and pngtest.c.  For usage
-information and restrictions (what little they are) on libpng, see
-png.h.  For a description on using zlib (the compression library used by
-libpng) and zlib's restrictions, see zlib.h
+Files included in this distribution
+-----------------------------------
 
-I have included a general makefile, as well as several machine and
-compiler specific ones, but you may have to modify one for your own needs.
+    ANNOUNCE      =>  Announcement of this version, with recent changes
+    AUTHORS       =>  List of contributing authors
+    CHANGES       =>  Description of changes between libpng versions
+    INSTALL       =>  Instructions to install libpng
+    LICENSE       =>  License to use and redistribute libpng
+    README        =>  This file
+    TODO          =>  Things not implemented in the current library
+    TRADEMARK     =>  Trademark information
+    example.c     =>  Example code for using libpng functions
+    libpng.3      =>  Manual page for libpng (includes libpng-manual.txt)
+    libpng-manual.txt  =>  Description of libpng and its functions
+    libpngpf.3    =>  Manual page for libpng's private functions (deprecated)
+    png.5         =>  Manual page for the PNG format
+    png.c         =>  Basic interface functions common to library
+    png.h         =>  Library function and interface declarations (public)
+    pngpriv.h     =>  Library function and interface declarations (private)
+    pngconf.h     =>  System specific library configuration (public)
+    pngstruct.h   =>  png_struct declaration (private)
+    pnginfo.h     =>  png_info struct declaration (private)
+    pngdebug.h    =>  debugging macros (private)
+    pngerror.c    =>  Error/warning message I/O functions
+    pngget.c      =>  Functions for retrieving info from struct
+    pngmem.c      =>  Memory handling functions
+    pngbar.png    =>  PNG logo, 88x31
+    pngnow.png    =>  PNG logo, 98x31
+    pngpread.c    =>  Progressive reading functions
+    pngread.c     =>  Read data/helper high-level functions
+    pngrio.c      =>  Lowest-level data read I/O functions
+    pngrtran.c    =>  Read data transformation functions
+    pngrutil.c    =>  Read data utility functions
+    pngset.c      =>  Functions for storing data into the info_struct
+    pngtest.c     =>  Library test program
+    pngtest.png   =>  Library test sample image
+    pngtrans.c    =>  Common data transformation functions
+    pngwio.c      =>  Lowest-level write I/O functions
+    pngwrite.c    =>  High-level write functions
+    pngwtran.c    =>  Write data transformations
+    pngwutil.c    =>  Write utility functions
+    arm/          =>  Optimized code for ARM Neon
+    intel/        =>  Optimized code for INTEL SSE2
+    loongarch/    =>  Optimized code for LoongArch LSX
+    mips/         =>  Optimized code for MIPS MSA and MIPS MMI
+    powerpc/      =>  Optimized code for PowerPC VSX
+    riscv/        =>  Optimized code for the RISC-V platform
+    ci/           =>  Scripts for continuous integration
+    contrib/      =>  External contributions
+        arm-neon/     =>  Optimized code for the ARM-NEON platform
+        mips-msa/     =>  Optimized code for the MIPS-MSA platform
+        powerpc-vsx/  =>  Optimized code for the POWERPC-VSX platform
+        examples/     =>  Examples of libpng usage
+        gregbook/     =>  Source code for PNG reading and writing, from
+                          "PNG: The Definitive Guide" by Greg Roelofs,
+                          O'Reilly, 1999
+        libtests/     =>  Test programs
+        pngexif/      =>  Program to inspect the EXIF information in PNG files
+        pngminim/     =>  Minimal decoder, encoder, and progressive decoder
+                          programs demonstrating the use of pngusr.dfa
+        pngminus/     =>  Simple pnm2png and png2pnm programs
+        pngsuite/     =>  Test images
+        riscv-rvv/    =>  Optimized code for the RISC-V Vector platform
+        testpngs/     =>  Test images
+        tools/        =>  Various tools
+        visupng/      =>  VisualPng, a Windows viewer for PNG images
+    projects/     =>  Project files and workspaces for various IDEs
+        owatcom/      =>  OpenWatcom project
+        visualc71/    =>  Microsoft Visual C++ 7.1 workspace
+        vstudio/      =>  Microsoft Visual Studio workspace
+    scripts/      =>  Scripts and makefiles for building libpng
+                      (see scripts/README.txt for the complete list)
+    tests/        =>  Test scripts
 
-You should use zlib 1.0.4 or later to run this, but it MAY work with
-versions as old as zlib 0.95.  Even so, there are bugs in older zlib
-versions which can cause the output of invalid compression streams for
-some images.  You will definitely need zlib 1.0.4 or later if you are
-taking advantage of the MS-DOS "far" structure allocation for the small
-and medium memory models.  You should also note that zlib is a
-compression library that is useful for more things than just PNG files.
-You can use zlib as a drop-in replacement for fread() and fwrite() if
-you are so inclined.
+Good luck, and happy coding!
 
-zlib should be available at the same place that libpng is.
-If not, it should be at ftp.uu.net in /graphics/png
-Eventually, it will be at ftp.uu.net in /pub/archiving/zip/zlib
-
-You may also want a copy of the PNG specification.  It is available
-as an RFC and a W3C Recommendation.  Failing
-these resources you can try ftp.uu.net in the /graphics/png directory.
-
-This code is currently being archived at ftp.uu.net in the
-/graphics/png directory, and on CompuServe, Lib 20 (PNG SUPPORT)
-at GO GRAPHSUP.  If you can't find it in any of those places,
-e-mail me, and I'll help you find it.
-
-If you have any code changes, requests, problems, etc., please e-mail
-them to me.  Also, I'd appreciate any make files or project files,
-and any modifications you needed to make to get libpng to compile,
-along with a #define variable to tell what compiler/system you are on.
-If you needed to add transformations to libpng, or wish libpng would
-provide the image in a different way, drop me a note (and code, if
-possible), so I can consider supporting the transformation.
-Finally, if you get any warning messages when compiling libpng
-(note: not zlib), and they are easy to fix, I'd appreciate the
-fix.  Please mention "libpng" somewhere in the subject line.  Thanks.
-
-This release was created and will be supported by myself (of course
-based in a large way on Guy's and Andreas' earlier work), and the PNG group.
-
-randeg@alum.rpi.edu
-png-implement@ccrc.wustl.edu
-
-You can't reach Guy, the original libpng author, at the addresses
-given in previous versions of this document.  He and Andreas will read mail
-addressed to the png-implement list, however.
-
-Please do not send general questions about PNG.  Send them to
-the address in the specification (png-group@w3.org).  At the same
-time, please do not send libpng questions to that address, send them to me
-or to png-implement@ccrc.wustl.edu.  I'll
-get them in the end anyway.  If you have a question about something
-in the PNG specification that is related to using libpng, send it
-to me.  Send me any questions that start with "I was using libpng,
-and ...".  If in doubt, send questions to me.  I'll bounce them
-to others, if necessary.
-
-Please do not send suggestions on how to change PNG.  We have
-been discussing PNG for three years now, and it is official and
-finished.  If you have suggestions for libpng, however, I'll
-gladly listen.  Even if your suggestion is not used for version
-1.0, it may be used later.
-
-Files in this distribution:
-
-      ANNOUNCE      =>  Announcement of this version, with recent changes
-      CHANGES       =>  Description of changes between libpng versions
-      KNOWNBUG      =>  List of known bugs and deficiencies
-      LICENSE       =>  License to use and redistribute libpng
-      README        =>  This file
-      TODO          =>  Things not implemented in the current library
-      Y2KINFO       =>  Statement of Y2K compliance
-      example.c     =>  Example code for using libpng functions
-      libpng.3      =>  manual page for libpng (includes libpng.txt)
-      libpng.txt    =>  Description of libpng and its functions
-      libpngpf.3    =>  manual page for libpng's private functions
-      png.5         =>  manual page for the PNG format
-      png.c         =>  Basic interface functions common to library
-      png.h         =>  Library function and interface declarations
-      pngconf.h     =>  System specific library configuration
-      pngasmrd.h    =>  Header file for assembler-coded functions
-      pngerror.c    =>  Error/warning message I/O functions
-      pngget.c      =>  Functions for retrieving info from struct
-      pngmem.c      =>  Memory handling functions
-      pngbar.png    =>  PNG logo, 88x31
-      pngnow.png    =>  PNG logo, 98x31
-      pngpread.c    =>  Progressive reading functions
-      pngread.c     =>  Read data/helper high-level functions
-      pngrio.c      =>  Lowest-level data read I/O functions
-      pngrtran.c    =>  Read data transformation functions
-      pngrutil.c    =>  Read data utility functions
-      pngset.c      =>  Functions for storing data into the info_struct
-      pngtest.c     =>  Library test program
-      pngtest.png   =>  Library test sample image
-      pngtrans.c    =>  Common data transformation functions
-      pngwio.c      =>  Lowest-level write I/O functions
-      pngwrite.c    =>  High-level write functions
-      pngwtran.c    =>  Write data transformations
-      pngwutil.c    =>  Write utility functions
-      contrib       =>  Contributions
-       gregbook         =>  source code for PNG reading and writing, from
-                            Greg Roelofs' "PNG: The Definitive Guide",
-                            O'Reilly, 1999
-       msvctest     =>  Builds and runs pngtest using a MSVC workspace
-       pngminus     =>  Simple pnm2png and png2pnm programs
-       pngsuite     =>  Test images
-       visupng      =>  Contains a MSVC workspace for VisualPng
-      projects      =>  Contains project files and workspaces for building DLL
-       beos             =>  Contains a Beos workspace for building libpng
-       borland          =>  Contains a Borland workspace for building libpng
-                            and zlib
-       msvc             =>  Contains a Microsoft Visual C++ (MSVC) workspace
-                            for building libpng and zlib
-       wince            =>  Contains a Microsoft Visual C++ (Windows CD Toolkit)
-                            workspace for building libpng and zlib on WindowsCE
-      scripts       =>  Directory containing scripts for building libpng:
-       descrip.mms      =>  VMS makefile for MMS or MMK
-       makefile.std     =>  Generic UNIX makefile (cc, creates static libpng.a)
-       makefile.linux   =>  Linux/ELF makefile
-                            (gcc, creates libpng.so.2.1.0.12beta1)
-       makefile.gcmmx   =>  Linux/ELF makefile (gcc, creates
-                            libpng.so.2.1.0.12beta1, uses assembler code
-                            tuned for Intel MMX platform)
-       makefile.gcc     =>  Generic makefile (gcc, creates static libpng.a)
-       makefile.knr     =>  Archaic UNIX Makefile that converts files with
-                            ansi2knr (Requires ansi2knr.c from
-                            ftp://ftp.cs.wisc.edu/ghost)
-       makefile.aix     =>  AIX makefile
-       makefile.cygwin  =>  Cygwin/gcc makefile
-       makefile.dec     =>  DEC Alpha UNIX makefile
-       makefile.hpgcc   =>  HPUX makefile using gcc
-       makefile.hpux    =>  HPUX (10.20 and 11.00) makefile
-       makefile.ibmc    =>  IBM C/C++ version 3.x for Win32 and OS/2 (static)
-       makefile.intel   =>  Intel C/C++ version 4.0 and later
-       libpng.icc       =>  Project file, IBM VisualAge/C++ 4.0 or later
-       makefile.macosx  =>  MACOS X Makefile
-       makefile.netbsd  =>  NetBSD/cc makefile, uses PNGGCCRD
-       makefile.sgi     =>  Silicon Graphics IRIX (cc, creates static lib)
-       makefile.sggcc   =>  Silicon Graphics (gcc, creates libpng.so.2.1.0.12beta1)
-       makefile.sunos   =>  Sun makefile
-       makefile.solaris =>  Solaris 2.X makefile
-                            (gcc, creates libpng.so.2.1.0.12beta1)
-       makefile.sco     =>  For SCO OSr5  ELF and Unixware 7 with Native cc
-       makefile.mips    =>  MIPS makefile
-       makefile.acorn   =>  Acorn makefile
-       makefile.amiga   =>  Amiga makefile
-       smakefile.ppc    =>  AMIGA smakefile for SAS C V6.58/7.00 PPC
-                            compiler (Requires SCOPTIONS, copied from
-                            scripts/SCOPTIONS.ppc)
-       makefile.atari   =>  Atari makefile
-       makefile.beos    =>  BEOS makefile for X86
-       makefile.bor     =>  Borland makefile (uses bcc)
-       makefile.bc32    =>  32-bit Borland C++ (all modules compiled in C mode)
-       makefile.bd32    =>  To make a png32bd.dll with Borland C++ 4.5
-       makefile.tc3     =>  Turbo C 3.0 makefile
-       makefile.dj2     =>  DJGPP 2 makefile
-       makefile.msc     =>  Microsoft C makefile
-       makefile.vcawin32 => makefile for Microsoft Visual C++ 5.0 and
-                            later (uses assembler code tuned for Intel MMX
-                            platform)
-       makefile.vcwin32 =>  makefile for Microsoft Visual C++ 4.0 and
-                            later (does not use assembler code)
-       makefile.os2     =>  OS/2 Makefile (gcc and emx, requires pngos2.def)
-       pngos2.def       =>  OS/2 module definition file used by makefile.os2
-       makefile.watcom  =>  Watcom 10a+ Makefile, 32-bit flat memory model
-       makevms.com      =>  VMS build script
-       pngdef.pas       =>  Defines for a png32bd.dll with Borland C++ 4.5
-       SCOPTIONS.ppc    =>  Used with smakefile.ppc
-
-Good luck, and happy coding.
-
--Glenn Randers-Pehrson
- Internet: randeg@alum.rpi.edu
-
--Andreas Eric Dilger
- Internet: adilger@enel.ucalgary.ca
- Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
-
--Guy Eric Schalnat
- (formerly of Group 42, Inc)
- Internet: gschal@infinet.com
+ * Cosmin Truta (current maintainer, since 2018)
+ * Glenn Randers-Pehrson (former maintainer, 1998-2018)
+ * Andreas Eric Dilger (former maintainer, 1996-1997)
+ * Guy Eric Schalnat (original author and former maintainer, 1995-1996)
+   (formerly of Group 42, Inc.)

TODO

@@ -1,24 +1,22 @@
-TODO - list of things to do for libpng:
+TODO list for libpng
+--------------------
 
-Final bug fixes.
-Improve API by hiding the png_struct and png_info structs.
-Finish work on the no-floating-point version (including gamma compensation)
-Better C++ wrapper/full C++ implementation?
-Fix problem with C++ and EXTERN "C".
-cHRM transformation.
-Improve setjmp/longjmp usage or remove it in favor of returning error codes.
-Add "grayscale->palette" transformation and "palette->grayscale" detection.
-Improved dithering.
-Multi-lingual error and warning message support.
-Complete sRGB transformation (presently it simply uses gamma=0.45455).
-Man pages for function calls.
-Better documentation.
-Better filter selection
-   (counting huffman bits/precompression?  filter inertia?  filter costs?).
-Histogram creation.
-Text conversion between different code pages (Latin-1 -> Mac and DOS).
-Should we always malloc 2^bit_depth PLTE/tRNS/hIST entries for safety?
-Build gamma tables using fixed point (and do away with floating point entirely).
-Use greater precision when changing to linear gamma for compositing against
-  background and doing rgb-to-gray transformation.
-Investigate pre-incremented loop counters and other loop constructions.
+ * Fix all defects (duh!)
+ * cHRM transformation.
+ * Palette creation.
+ * "grayscale->palette" transformation and "palette->grayscale" detection.
+ * Improved dithering.
+ * Multi-lingual error and warning message support.
+ * Complete sRGB transformation.  (Currently it simply uses gamma=0.45455.)
+ * Man pages for function calls.
+ * Better documentation.
+ * Better filter selection
+   (e.g., counting huffman bits/precompression; filter inertia; filter costs).
+ * Histogram creation.
+ * Text conversion between different code pages (e.g., Latin-1 to Mac).
+ * Avoid building gamma tables whenever possible.
+ * Greater precision in changing to linear gamma for compositing against
+   background, and in doing rgb-to-gray transformations.
+ * Investigate pre-incremented loop counters and other loop constructions.
+ * Interpolated method of handling interlacing.
+ * More validations for libpng transformations.

TRADEMARK

@@ -0,0 +1,8 @@
+TRADEMARK
+=========
+
+The name "libpng" has not been registered by the Copyright owners
+as a trademark in any jurisdiction.  However, because libpng has
+been distributed and maintained world-wide, continually since 1995,
+the Copyright owners claim "common-law trademark protection" in any
+jurisdiction where common-law trademark is recognized.

Y2KINFO

@@ -1,55 +0,0 @@
-   Y2K compliance in libpng:
-   =========================
-
-      May 14, 2001
-
-      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 1.0.12beta1 are Y2K compliant.  It is my belief that earlier
-      versions were also Y2K compliant.
-
-      Libpng only has three year fields.  One is a 2-byte unsigned integer
-      that will hold years up to 65535.  The other two hold the date in text
-      format, and will hold years up to 9999.
-
-      The integer is
-          "png_uint_16 year" in png_time_struct.
-
-      The strings are
-          "png_charp time_buffer" in png_struct and
-          "near_time_buffer", which is a local character string in png.c.
-
-      There are seven time-related functions:
-
-          png_convert_to_rfc_1123() in png.c
-            (formerly png_convert_to_rfc_1152() in error)
-          png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
-          png_convert_from_time_t() in pngwrite.c
-          png_get_tIME() in pngget.c
-          png_handle_tIME() in pngrutil.c, called in pngread.c
-          png_set_tIME() in pngset.c
-          png_write_tIME() in pngwutil.c, called in pngwrite.c
-
-      All appear to handle dates properly in a Y2K environment.  The
-      png_convert_from_time_t() function calls gmtime() to convert from system
-      clock time, which returns (year - 1900), which we properly convert to
-      the full 4-digit year.  There is a possibility that applications using
-      libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
-      function, or that they are incorrectly passing only a 2-digit year
-      instead of "year - 1900" into the png_convert_from_struct_tm() function,
-      but this is not under our control.  The libpng documentation has always
-      stated that it works with 4-digit years, and the APIs have been
-      documented as such.
-
-      The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
-      integer to hold the year, and can hold years as large as 65535.
-
-      zlib, upon which libpng depends, is also Y2K compliant.  It contains
-      no date-related code.
-
-
-         Glenn Randers-Pehrson
-         libpng maintainer
-         PNG Development Group

arm/arm_init.c

@@ -0,0 +1,138 @@
+/* arm_init.c - NEON optimised filter functions
+ *
+ * Copyright (c) 2018-2022 Cosmin Truta
+ * Copyright (c) 2014,2016 Glenn Randers-Pehrson
+ * Written by Mans Rullgard, 2011.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+/* This module requires POSIX 1003.1 functions. */
+#define _POSIX_SOURCE 1
+
+#include "../pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+#if PNG_ARM_NEON_OPT > 0
+#ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
+/* WARNING: it is strongly recommended that you do not build libpng with
+ * run-time checks for CPU features if at all possible.  In the case of the ARM
+ * NEON instructions there is no processor-specific way of detecting the
+ * presence of the required support, therefore run-time detection is extremely
+ * OS specific.
+ *
+ * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
+ * a fragment of C source code which defines the png_have_neon function.  There
+ * are a number of implementations in contrib/arm-neon, but the only one that
+ * has partial support is contrib/arm-neon/linux.c - a generic Linux
+ * implementation which reads /proc/cpufino.
+ */
+#include <signal.h> /* for sig_atomic_t */
+
+#ifndef PNG_ARM_NEON_FILE
+#  if defined(__aarch64__) || defined(_M_ARM64)
+     /* ARM Neon is expected to be unconditionally available on ARM64. */
+#    error PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on ARM64
+#  elif defined(__ARM_NEON__) || defined(__ARM_NEON)
+     /* ARM Neon is expected to be available on the target CPU architecture. */
+#    error PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on this CPU arch
+#  elif defined(__linux__)
+#    define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
+#  else
+#    error No support for run-time ARM Neon checking; use compile-time options
+#  endif
+#endif
+
+static int png_have_neon(png_structp png_ptr);
+#ifdef PNG_ARM_NEON_FILE
+#  include PNG_ARM_NEON_FILE
+#endif
+#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
+
+#ifndef PNG_ALIGNED_MEMORY_SUPPORTED
+#  error ALIGNED_MEMORY is required; please define PNG_ALIGNED_MEMORY_SUPPORTED
+#endif
+
+void
+png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
+{
+   /* The switch statement is compiled in for ARM_NEON_API, the call to
+    * png_have_neon is compiled in for ARM_NEON_CHECK.  If both are defined
+    * the check is only performed if the API has not set the NEON option on
+    * or off explicitly.  In this case the check controls what happens.
+    *
+    * If the CHECK is not compiled in and the option is UNSET the behavior prior
+    * to 1.6.7 was to use the NEON code - this was a bug caused by having the
+    * 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)
+   {
+      case PNG_OPTION_UNSET:
+         /* Allow the run-time check to execute if it has been enabled -
+          * thus both API and CHECK can be turned on.  If it isn't supported
+          * this case will fall through to the 'default' below, which just
+          * returns.
+          */
+#endif /* PNG_ARM_NEON_API_SUPPORTED */
+#ifdef PNG_ARM_NEON_CHECK_SUPPORTED
+         {
+            static volatile sig_atomic_t no_neon = -1; /* not checked */
+
+            if (no_neon < 0)
+               no_neon = !png_have_neon(pp);
+
+            if (no_neon)
+               return;
+         }
+#ifdef PNG_ARM_NEON_API_SUPPORTED
+         break;
+#endif
+#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
+
+#ifdef PNG_ARM_NEON_API_SUPPORTED
+      default: /* OFF or INVALID */
+         return;
+
+      case PNG_OPTION_ON:
+         /* Option turned on */
+         break;
+   }
+#endif
+
+   /* IMPORTANT: any new external functions used here must be declared using
+    * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
+    * 'prefix' option to configure works:
+    *
+    *    ./configure --with-libpng-prefix=foobar_
+    *
+    * Verify you have got this right by running the above command, doing a build
+    * and examining pngprefix.h; it must contain a #define for every external
+    * function you add.  (Notice that this happens automatically for the
+    * initialization function.)
+    */
+   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
+
+   if (bpp == 3)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+         png_read_filter_row_paeth3_neon;
+   }
+
+   else if (bpp == 4)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+          png_read_filter_row_paeth4_neon;
+   }
+}
+#endif /* PNG_ARM_NEON_OPT > 0 */
+#endif /* READ */

arm/filter_neon.S

@@ -0,0 +1,60 @@
+/* filter_neon.S - placeholder file
+ *
+ * Copyright (c) 2024 Cosmin Truta
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+/* IMPORTANT NOTE:
+ *
+ * Historically, the hand-coded assembler implementation of Neon optimizations
+ * in this module had not been in sync with the intrinsics-based implementation
+ * in filter_neon_intrinsics.c and palette_neon_intrinsics.c, at least since
+ * the introduction of riffled palette optimizations. Moreover, the assembler
+ * code used to work on 32-bit ARM only, and it caused problems, even if empty,
+ * on 64-bit ARM.
+ *
+ * All references to this module from our internal build scripts and projects
+ * have been removed.
+ *
+ * For the external projects that might still expect this module to be present,
+ * we leave this stub in place, for the remaining lifetime of libpng-1.6.x.
+ * Everything should continue to function normally, as long as there are no
+ * deliberate attempts to use the old hand-made assembler code. A build error
+ * will be raised otherwise.
+ */
+
+/* This is required to get the symbol renames, which are #defines, and the
+ * definitions (or not) of PNG_ARM_NEON_OPT and PNG_ARM_NEON_IMPLEMENTATION.
+ */
+#define PNG_VERSION_INFO_ONLY
+#include "../pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+#if PNG_ARM_NEON_IMPLEMENTATION == 2 /* hand-coded assembler */
+#if PNG_ARM_NEON_OPT > 0
+
+#if defined(__clang__)
+#define GNUC_VERSION 0 /* not gcc, although it might pretend to be */
+#elif defined(__GNUC__)
+#define GNUC_MAJOR (__GNUC__ + 0)
+#define GNUC_MINOR (__GNUC_MINOR__ + 0)
+#define GNUC_PATCHLEVEL (__GNUC_PATCHLEVEL__ + 0)
+#define GNUC_VERSION (GNUC_MAJOR * 10000 + GNUC_MINOR * 100 + GNUC_PATCHLEVEL)
+#else
+#define GNUC_VERSION 0 /* not gcc */
+#endif
+
+#if (GNUC_VERSION > 0) && (GNUC_VERSION < 40300)
+#error "PNG_ARM_NEON is not supported with gcc versions earlier than 4.3.0"
+#elif GNUC_VERSION == 40504
+#error "PNG_ARM_NEON is not supported with gcc version 4.5.4"
+#else
+#error "Please use 'arm/*_neon_intrinsics.c' for PNG_ARM_NEON support"
+#endif
+
+#endif /* PNG_ARM_NEON_OPT > 0 */
+#endif /* PNG_ARM_NEON_IMPLEMENTATION == 2 */
+#endif /* READ */

arm/filter_neon_intrinsics.c

@@ -0,0 +1,401 @@
+/* filter_neon_intrinsics.c - NEON optimised filter functions
+ *
+ * Copyright (c) 2018 Cosmin Truta
+ * Copyright (c) 2014,2016 Glenn Randers-Pehrson
+ * Written by James Yu <james.yu at linaro.org>, October 2013.
+ * Based on filter_neon.S, written by Mans Rullgard, 2011.
+ *
+ * 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
+
+/* This code requires -mfpu=neon on the command line: */
+#if PNG_ARM_NEON_IMPLEMENTATION == 1 /* intrinsics code from pngpriv.h */
+
+#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64)
+#  include <arm64_neon.h>
+#else
+#  include <arm_neon.h>
+#endif
+
+/* libpng row pointers are not necessarily aligned to any particular boundary,
+ * however this code will only work with appropriate alignment.  arm/arm_init.c
+ * checks for this (and will not compile unless it is done). This code uses
+ * variants of png_aligncast to avoid compiler warnings.
+ */
+#define png_ptr(type,pointer) png_aligncast(type *,pointer)
+#define png_ptrc(type,pointer) png_aligncastconst(const type *,pointer)
+
+/* The following relies on a variable 'temp_pointer' being declared with type
+ * 'type'.  This is written this way just to hide the GCC strict aliasing
+ * warning; note that the code is safe because there never is an alias between
+ * the input and output pointers.
+ *
+ * When compiling with MSVC ARM64, the png_ldr macro can't be passed directly
+ * to vst4_lane_u32, because of an internal compiler error inside MSVC.
+ * To avoid this compiler bug, we use a temporary variable (vdest_val) to store
+ * the result of png_ldr.
+ */
+#define png_ldr(type,pointer)\
+   (temp_pointer = png_ptr(type,pointer), *temp_pointer)
+
+#if PNG_ARM_NEON_OPT > 0
+
+void
+png_read_filter_row_up_neon(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp = 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;
+
+      qrp = vld1q_u8(rp);
+      qpp = vld1q_u8(pp);
+      qrp = vaddq_u8(qrp, qpp);
+      vst1q_u8(rp, qrp);
+   }
+}
+
+void
+png_read_filter_row_sub3_neon(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp = row;
+   png_bytep rp_stop = row + row_info->rowbytes;
+
+   uint8x16_t vtmp = vld1q_u8(rp);
+   uint8x8x2_t *vrpt = png_ptr(uint8x8x2_t, &vtmp);
+   uint8x8x2_t vrp = *vrpt;
+
+   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;
+      uint32x2_t *temp_pointer;
+
+      vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 3);
+      vdest.val[0] = vadd_u8(vdest.val[3], vrp.val[0]);
+      vtmp2 = vext_u8(vrp.val[0], vrp.val[1], 6);
+      vdest.val[1] = vadd_u8(vdest.val[0], vtmp1);
+
+      vtmp1 = vext_u8(vrp.val[1], vrp.val[1], 1);
+      vdest.val[2] = vadd_u8(vdest.val[1], vtmp2);
+      vdest.val[3] = vadd_u8(vdest.val[2], vtmp1);
+
+      vtmp = vld1q_u8(rp + 12);
+      vrpt = png_ptr(uint8x8x2_t, &vtmp);
+      vrp = *vrpt;
+
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[0]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[1]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[2]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[3]), 0);
+      rp += 3;
+   }
+
+   PNG_UNUSED(prev_row)
+}
+
+void
+png_read_filter_row_sub4_neon(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp = row;
+   png_bytep rp_stop = row + row_info->rowbytes;
+
+   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));
+      uint8x8x4_t *vrpt = png_ptr(uint8x8x4_t,&vtmp);
+      uint8x8x4_t vrp = *vrpt;
+      uint32x2x4_t *temp_pointer;
+      uint32x2x4_t vdest_val;
+
+      vdest.val[0] = vadd_u8(vdest.val[3], vrp.val[0]);
+      vdest.val[1] = vadd_u8(vdest.val[0], vrp.val[1]);
+      vdest.val[2] = vadd_u8(vdest.val[1], vrp.val[2]);
+      vdest.val[3] = vadd_u8(vdest.val[2], vrp.val[3]);
+
+      vdest_val = png_ldr(uint32x2x4_t, &vdest);
+      vst4_lane_u32(png_ptr(uint32_t,rp), vdest_val, 0);
+   }
+
+   PNG_UNUSED(prev_row)
+}
+
+void
+png_read_filter_row_avg3_neon(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp = row;
+   png_const_bytep pp = prev_row;
+   png_bytep rp_stop = row + row_info->rowbytes;
+
+   uint8x16_t vtmp;
+   uint8x8x2_t *vrpt;
+   uint8x8x2_t vrp;
+   uint8x8x4_t vdest;
+   vdest.val[3] = vdup_n_u8(0);
+
+   vtmp = vld1q_u8(rp);
+   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;
+
+      uint8x8x2_t *vppt;
+      uint8x8x2_t vpp;
+
+      uint32x2_t *temp_pointer;
+
+      vtmp = vld1q_u8(pp);
+      vppt = png_ptr(uint8x8x2_t,&vtmp);
+      vpp = *vppt;
+
+      vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 3);
+      vdest.val[0] = vhadd_u8(vdest.val[3], vpp.val[0]);
+      vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+
+      vtmp2 = vext_u8(vpp.val[0], vpp.val[1], 3);
+      vtmp3 = vext_u8(vrp.val[0], vrp.val[1], 6);
+      vdest.val[1] = vhadd_u8(vdest.val[0], vtmp2);
+      vdest.val[1] = vadd_u8(vdest.val[1], vtmp1);
+
+      vtmp2 = vext_u8(vpp.val[0], vpp.val[1], 6);
+      vtmp1 = vext_u8(vrp.val[1], vrp.val[1], 1);
+
+      vtmp = vld1q_u8(rp + 12);
+      vrpt = png_ptr(uint8x8x2_t,&vtmp);
+      vrp = *vrpt;
+
+      vdest.val[2] = vhadd_u8(vdest.val[1], vtmp2);
+      vdest.val[2] = vadd_u8(vdest.val[2], vtmp3);
+
+      vtmp2 = vext_u8(vpp.val[1], vpp.val[1], 1);
+
+      vdest.val[3] = vhadd_u8(vdest.val[2], vtmp2);
+      vdest.val[3] = vadd_u8(vdest.val[3], vtmp1);
+
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[0]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[1]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[2]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[3]), 0);
+      rp += 3;
+   }
+}
+
+void
+png_read_filter_row_avg4_neon(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp = row;
+   png_bytep rp_stop = row + row_info->rowbytes;
+   png_const_bytep pp = prev_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;
+      uint8x8x4_t *vrpt, *vppt;
+      uint8x8x4_t vrp, vpp;
+      uint32x2x4_t *temp_pointer;
+      uint32x2x4_t vdest_val;
+
+      vtmp = vld4_u32(png_ptr(uint32_t,rp));
+      vrpt = png_ptr(uint8x8x4_t,&vtmp);
+      vrp = *vrpt;
+      vtmp = vld4_u32(png_ptrc(uint32_t,pp));
+      vppt = png_ptr(uint8x8x4_t,&vtmp);
+      vpp = *vppt;
+
+      vdest.val[0] = vhadd_u8(vdest.val[3], vpp.val[0]);
+      vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+      vdest.val[1] = vhadd_u8(vdest.val[0], vpp.val[1]);
+      vdest.val[1] = vadd_u8(vdest.val[1], vrp.val[1]);
+      vdest.val[2] = vhadd_u8(vdest.val[1], vpp.val[2]);
+      vdest.val[2] = vadd_u8(vdest.val[2], vrp.val[2]);
+      vdest.val[3] = vhadd_u8(vdest.val[2], vpp.val[3]);
+      vdest.val[3] = vadd_u8(vdest.val[3], vrp.val[3]);
+
+      vdest_val = png_ldr(uint32x2x4_t, &vdest);
+      vst4_lane_u32(png_ptr(uint32_t,rp), vdest_val, 0);
+   }
+}
+
+static uint8x8_t
+paeth(uint8x8_t a, uint8x8_t b, uint8x8_t c)
+{
+   uint8x8_t d, e;
+   uint16x8_t p1, pa, pb, pc;
+
+   p1 = vaddl_u8(a, b); /* a + b */
+   pc = vaddl_u8(c, c); /* c * 2 */
+   pa = vabdl_u8(b, c); /* pa */
+   pb = vabdl_u8(a, c); /* pb */
+   pc = vabdq_u16(p1, pc); /* pc */
+
+   p1 = vcleq_u16(pa, pb); /* pa <= pb */
+   pa = vcleq_u16(pa, pc); /* pa <= pc */
+   pb = vcleq_u16(pb, pc); /* pb <= pc */
+
+   p1 = vandq_u16(p1, pa); /* pa <= pb && pa <= pc */
+
+   d = vmovn_u16(pb);
+   e = vmovn_u16(p1);
+
+   d = vbsl_u8(d, b, c);
+   e = vbsl_u8(e, a, d);
+
+   return e;
+}
+
+void
+png_read_filter_row_paeth3_neon(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp = row;
+   png_const_bytep pp = prev_row;
+   png_bytep rp_stop = row + row_info->rowbytes;
+
+   uint8x16_t vtmp;
+   uint8x8x2_t *vrpt;
+   uint8x8x2_t vrp;
+   uint8x8_t vlast = vdup_n_u8(0);
+   uint8x8x4_t vdest;
+   vdest.val[3] = vdup_n_u8(0);
+
+   vtmp = vld1q_u8(rp);
+   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;
+      uint8x8x2_t vpp;
+      uint8x8_t vtmp1, vtmp2, vtmp3;
+      uint32x2_t *temp_pointer;
+
+      vtmp = vld1q_u8(pp);
+      vppt = png_ptr(uint8x8x2_t,&vtmp);
+      vpp = *vppt;
+
+      vdest.val[0] = paeth(vdest.val[3], vpp.val[0], vlast);
+      vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+
+      vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 3);
+      vtmp2 = vext_u8(vpp.val[0], vpp.val[1], 3);
+      vdest.val[1] = paeth(vdest.val[0], vtmp2, vpp.val[0]);
+      vdest.val[1] = vadd_u8(vdest.val[1], vtmp1);
+
+      vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 6);
+      vtmp3 = vext_u8(vpp.val[0], vpp.val[1], 6);
+      vdest.val[2] = paeth(vdest.val[1], vtmp3, vtmp2);
+      vdest.val[2] = vadd_u8(vdest.val[2], vtmp1);
+
+      vtmp1 = vext_u8(vrp.val[1], vrp.val[1], 1);
+      vtmp2 = vext_u8(vpp.val[1], vpp.val[1], 1);
+
+      vtmp = vld1q_u8(rp + 12);
+      vrpt = png_ptr(uint8x8x2_t,&vtmp);
+      vrp = *vrpt;
+
+      vdest.val[3] = paeth(vdest.val[2], vtmp2, vtmp3);
+      vdest.val[3] = vadd_u8(vdest.val[3], vtmp1);
+
+      vlast = vtmp2;
+
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[0]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[1]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[2]), 0);
+      rp += 3;
+      vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[3]), 0);
+      rp += 3;
+   }
+}
+
+void
+png_read_filter_row_paeth4_neon(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp = row;
+   png_bytep rp_stop = row + row_info->rowbytes;
+   png_const_bytep pp = prev_row;
+
+   uint8x8_t vlast = vdup_n_u8(0);
+   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;
+      uint8x8x4_t *vrpt, *vppt;
+      uint8x8x4_t vrp, vpp;
+      uint32x2x4_t *temp_pointer;
+      uint32x2x4_t vdest_val;
+
+      vtmp = vld4_u32(png_ptr(uint32_t,rp));
+      vrpt = png_ptr(uint8x8x4_t,&vtmp);
+      vrp = *vrpt;
+      vtmp = vld4_u32(png_ptrc(uint32_t,pp));
+      vppt = png_ptr(uint8x8x4_t,&vtmp);
+      vpp = *vppt;
+
+      vdest.val[0] = paeth(vdest.val[3], vpp.val[0], vlast);
+      vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+      vdest.val[1] = paeth(vdest.val[0], vpp.val[1], vpp.val[0]);
+      vdest.val[1] = vadd_u8(vdest.val[1], vrp.val[1]);
+      vdest.val[2] = paeth(vdest.val[1], vpp.val[2], vpp.val[1]);
+      vdest.val[2] = vadd_u8(vdest.val[2], vrp.val[2]);
+      vdest.val[3] = paeth(vdest.val[2], vpp.val[3], vpp.val[2]);
+      vdest.val[3] = vadd_u8(vdest.val[3], vrp.val[3]);
+
+      vlast = vpp.val[3];
+
+      vdest_val = png_ldr(uint32x2x4_t, &vdest);
+      vst4_lane_u32(png_ptr(uint32_t,rp), vdest_val, 0);
+   }
+}
+
+#endif /* PNG_ARM_NEON_OPT > 0 */
+#endif /* PNG_ARM_NEON_IMPLEMENTATION == 1 (intrinsics) */
+#endif /* READ */

arm/palette_neon_intrinsics.c

@@ -0,0 +1,150 @@
+/* palette_neon_intrinsics.c - NEON optimised palette expansion functions
+ *
+ * Copyright (c) 2018-2019 Cosmin Truta
+ * Copyright (c) 2017-2018 Arm Holdings. All rights reserved.
+ * Written by Richard Townsend <Richard.Townsend@arm.com>, February 2017.
+ *
+ * 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"
+
+#if PNG_ARM_NEON_IMPLEMENTATION == 1
+
+#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64)
+#  include <arm64_neon.h>
+#else
+#  include <arm_neon.h>
+#endif
+
+/* Build an RGBA8 palette from the separate RGB and alpha palettes. */
+void
+png_riffle_palette_neon(png_structrp png_ptr)
+{
+   png_const_colorp palette = png_ptr->palette;
+   png_bytep riffled_palette = png_ptr->riffled_palette;
+   png_const_bytep trans_alpha = png_ptr->trans_alpha;
+   int num_trans = png_ptr->num_trans;
+   int i;
+
+   /* Initially black, opaque. */
+   uint8x16x4_t w = {{
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0xff),
+   }};
+
+   png_debug(1, "in png_riffle_palette_neon");
+
+   /* First, riffle the RGB colours into an RGBA8 palette.
+    * The alpha component is set to opaque for now.
+    */
+   for (i = 0; i < 256; i += 16)
+   {
+      uint8x16x3_t v = vld3q_u8((png_const_bytep)(palette + i));
+      w.val[0] = v.val[0];
+      w.val[1] = v.val[1];
+      w.val[2] = v.val[2];
+      vst4q_u8(riffled_palette + (i << 2), w);
+   }
+
+   /* Fix up the missing transparency values. */
+   for (i = 0; i < num_trans; i++)
+      riffled_palette[(i << 2) + 3] = trans_alpha[i];
+}
+
+/* Expands a palettized row into RGBA8. */
+int
+png_do_expand_palette_rgba8_neon(png_structrp png_ptr, png_row_infop row_info,
+    png_const_bytep row, png_bytepp ssp, png_bytepp ddp)
+{
+   png_uint_32 row_width = row_info->width;
+   const png_uint_32 *riffled_palette =
+      png_aligncastconst(png_const_uint_32p, png_ptr->riffled_palette);
+   const png_uint_32 pixels_per_chunk = 4;
+   png_uint_32 i;
+
+   png_debug(1, "in png_do_expand_palette_rgba8_neon");
+
+   PNG_UNUSED(row)
+   if (row_width < pixels_per_chunk)
+      return 0;
+
+   /* This function originally gets the last byte of the output row.
+    * The NEON part writes forward from a given position, so we have
+    * to seek this back by 4 pixels x 4 bytes.
+    */
+   *ddp = *ddp - ((pixels_per_chunk * sizeof(png_uint_32)) - 1);
+
+   for (i = 0; i < row_width; i += pixels_per_chunk)
+   {
+      uint32x4_t cur;
+      png_bytep sp = *ssp - i, dp = *ddp - (i << 2);
+      cur = vld1q_dup_u32 (riffled_palette + *(sp - 3));
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 2), cur, 1);
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 1), cur, 2);
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 0), cur, 3);
+      vst1q_u32((void *)dp, cur);
+   }
+   if (i != row_width)
+   {
+      /* Remove the amount that wasn't processed. */
+      i -= pixels_per_chunk;
+   }
+
+   /* Decrement output pointers. */
+   *ssp = *ssp - i;
+   *ddp = *ddp - (i << 2);
+   return i;
+}
+
+/* Expands a palettized row into RGB8. */
+int
+png_do_expand_palette_rgb8_neon(png_structrp png_ptr, png_row_infop row_info,
+    png_const_bytep row, png_bytepp ssp, png_bytepp ddp)
+{
+   png_uint_32 row_width = row_info->width;
+   png_const_bytep palette = (png_const_bytep)png_ptr->palette;
+   const png_uint_32 pixels_per_chunk = 8;
+   png_uint_32 i;
+
+   png_debug(1, "in png_do_expand_palette_rgb8_neon");
+
+   PNG_UNUSED(row)
+   if (row_width <= pixels_per_chunk)
+      return 0;
+
+   /* Seeking this back by 8 pixels x 3 bytes. */
+   *ddp = *ddp - ((pixels_per_chunk * sizeof(png_color)) - 1);
+
+   for (i = 0; i < row_width; i += pixels_per_chunk)
+   {
+      uint8x8x3_t cur;
+      png_bytep sp = *ssp - i, dp = *ddp - ((i << 1) + i);
+      cur = vld3_dup_u8(palette + sizeof(png_color) * (*(sp - 7)));
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 6)), cur, 1);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 5)), cur, 2);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 4)), cur, 3);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 3)), cur, 4);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 2)), cur, 5);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 1)), cur, 6);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 0)), cur, 7);
+      vst3_u8((void *)dp, cur);
+   }
+
+   if (i != row_width)
+   {
+      /* Remove the amount that wasn't processed. */
+      i -= pixels_per_chunk;
+   }
+
+   /* Decrement output pointers. */
+   *ssp = *ssp - i;
+   *ddp = *ddp - ((i << 1) + i);
+   return i;
+}
+
+#endif /* PNG_ARM_NEON_IMPLEMENTATION */

autogen.sh

@@ -0,0 +1,226 @@
+#! /bin/sh
+#
+# Run 'autoreconf' to build 'configure', 'Makefile.in' and other configure
+# control files.
+#
+# The first time this is run on a GIT checkout the only files that exist are
+# configure.ac and Makefile.am; all of the autotools support scripts are
+# missing.  They are instantiated with autoreconf --force --install.
+#
+# For regular ("tarball") distributions all the files should exist.  We do not
+# want them to be updated *under any circumstances*.  It should never be
+# necessary to run autogen.sh because ./configure --enable-maintainer-mode says
+# what to do if Makefile.am or configure.ac are changed.
+#
+# It is *probably* OK to update the files on a GIT checkout, because they have
+# come from the local tools, but leave that to the user who is assumed to know
+# whether it is ok or required.
+#
+# This script is intended to work without arguments, there are, however, hidden
+# arguments (a) for use while testing the script and (b) to fix up systems that
+# have been broken.  If (b) is required the script prompts for the correct
+# options.  For this reason the options are *NOT* documented in the help; this
+# is deliberate; UTSL.
+#
+clean=
+maintainer=
+while test $# -gt 0
+do
+   case "$1" in
+      --maintainer)
+         maintainer=1;;
+
+      --clean)
+         clean=1;;
+
+      *)
+         exec >&2
+         echo "$0: usage: ./autogen.sh"
+         if test -d .git
+         then
+            echo "  ./autogen.sh generates the configure script and"
+            echo "  Makefile.in, or refreshes them after changes to Makefile.am"
+            echo "  or configure.ac.  You may prefer to just run autoreconf."
+         elif test -z "$maintainer"
+         then
+            echo "  DO NOT RUN THIS SCRIPT."
+            echo "  If you need to change Makefile.am or configure.ac then you"
+            echo "  also need to run ./configure --enable-maintainer-mode and"
+            echo "  use the appropriate autotools, *NOT* this script, to update"
+            echo "  everything, please check the documentation of autoreconf."
+            echo "  WARNING: libpng is intentionally generated with a known,"
+            echo "  fixed, set of autotools.  It is known *NOT* to work with"
+            echo "  the collection of autotools distributed on highly reputable"
+            echo "  operating systems."
+            echo "  Remember: autotools is GNU software, you are expected to"
+            echo "  pay for support."
+         else
+            echo "  You have run autogen.sh with --maintainer enabled and you"
+            echo "  are not using a GIT distribution, then you have given an"
+            echo "  unrecognized argument.  This is not good. --maintainer"
+            echo "  switches off any assumptions that you might not know what"
+            echo "  you are doing."
+         fi
+         exit 1;;
+   esac
+
+   shift
+done
+#
+# First check for a set of the autotools files; if absent then this is assumed
+# to be a GIT version and the local autotools must be used.  If present this
+# is a tarball distribution and the script should not be used.  If partially
+# present bad things are happening.
+#
+# The autotools generated files:
+libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in
+   config.sub configure depcomp install-sh ltmain.sh missing\
+   test-driver"
+#
+# Files generated by versions of autoconf >2.68 or automake >1.13 (i.e. later
+# versions than those required by configure.ac):
+libpng_autotools_extra="compile config.h.in~"
+#
+# These are separate because 'maintainer-clean' does not remove them.
+libpng_libtool_files="scripts/autoconf/libtool.m4 scripts/autoconf/ltoptions.m4\
+   scripts/autoconf/ltsugar.m4 scripts/autoconf/ltversion.m4\
+   scripts/autoconf/lt~obsolete.m4"
+
+libpng_autotools_dirs="autom4te.cache" # not required
+#
+# The configure generated files:
+libpng_configure_files="Makefile config.h config.log config.status\
+   libpng-config libpng.pc libtool stamp-h1"
+
+libpng_configure_dirs=".deps"
+#
+# We must remove the configure generated files as well as the autotools
+# generated files if autotools are regenerated because otherwise if configure
+# has been run without "--enable-maintainer-mode" make can do a partial update
+# of Makefile.  These functions do the two bits of cleaning.
+clean_autotools(){
+   rm -rf $libpng_autotools_files $libpng_libtool_files $libpng_autotools_dirs
+   rm -rf $libpng_autotools_extra
+}
+
+clean_configure(){
+   rm -rf $libpng_configure_files $libpng_configure_dirs
+}
+#
+# Clean: remove everything (this is to help with testing)
+if test -n "$clean"
+then
+   clean_configure
+   if test -n "$maintainer"
+   then
+      clean_autotools
+   fi
+
+   exit 0
+fi
+#
+# Validate the distribution.
+libpng_autotools_file_found=
+libpng_autotools_file_missing=
+for file in $libpng_autotools_files
+do
+   if test -f  "$file"
+   then
+      libpng_autotools_file_found=1
+   else
+      libpng_autotools_file_missing=1
+   fi
+done
+#
+# Presence of one of these does not *invalidate* missing, but absence
+# invalidates found.
+for file in $libpng_libtool_files
+do
+   if test ! -f "$file"
+   then
+      libpng_autotools_file_missing=1
+   fi
+done
+#
+# The cache directory doesn't matter - it will be regenerated and does not exist
+# anyway in a tarball.
+#
+# Either everything is missing or everything is there, the --maintainer option
+# just changes this so that the mode is set to generate all the files.
+mode=
+if test -z "$libpng_autotools_file_found" -o -n "$maintainer"
+then
+   mode="autoreconf"
+else
+   if test -n "$libpng_autotools_file_missing"
+   then
+      mode="broken"
+   else
+      mode="configure"
+   fi
+fi
+#
+# So:
+case "$mode" in
+   autoreconf)
+      # Clean in case configure files exist
+      clean_configure
+      clean_autotools
+      # Everything must be initialized, so use --force
+      if autoreconf --warnings=all --force --install
+      then
+         missing=
+         for file in $libpng_autotools_files
+         do
+            test -f "$file" || missing=1
+         done
+         # ignore the cache directory
+         test -z "$missing" || {
+            exec >&2
+            echo "autoreconf was run, but did not produce all the expected"
+            echo "files.  It is likely that your autotools installation is"
+            echo "not compatible with that expected by libpng."
+            exit 1
+         }
+      else
+         exec >&2
+         echo "autoreconf failed: your version of autotools is incompatible"
+         echo "with this libpng version.  Please use a distributed archive"
+         echo "(which includes the autotools generated files) and run configure"
+         echo "instead."
+         exit 1
+      fi;;
+
+   configure)
+      if test -d .git
+      then
+         exec >&2
+         echo "ERROR: running autoreconf on an initialized system"
+         echo "  This is not necessary; it is only necessary to remake the"
+         echo "  autotools generated files if Makefile.am or configure.ac"
+         echo "  change and make does the right thing with:"
+         echo
+         echo "     ./configure --enable-maintainer-mode."
+         echo
+         echo "  You can run autoreconf yourself if you don't like maintainer"
+         echo "  mode and you can also just run autoreconf -f -i to initialize"
+         echo "  everything in the first place; this script is only for"
+         echo "  compatibility with prior releases."
+         exit 1
+      else
+         exec >&2
+         echo "autogen.sh is intended only to generate 'configure' on systems"
+         echo "that do not have it.  You have a complete 'configure', if you"
+         echo "need to change Makefile.am or configure.ac you also need to"
+         echo "run configure with the --enable-maintainer-mode option."
+         exit 1
+      fi;;
+
+   broken)
+      exec >&2
+      echo "Your system has a partial set of autotools generated files."
+      echo "autogen.sh is unable to proceed.  The full set of files is"
+      echo "contained in the libpng 'tar' distribution archive and you do"
+      echo "not need to run autogen.sh if you use it."
+      exit 1;;
+esac

ci/.shellcheckrc

@@ -0,0 +1,11 @@
+# Disable the "expressions don't expand in single quotes, use double quotes"
+# advice. We need the regular expressions to remain uninterpolated.
+disable=SC2016
+
+# Disable the "variable appears unused" warning caused by the use of getopts
+# with an obligatory (but unused) variable name in the main function.
+disable=SC2034
+
+# Disable all the "quote to prevent globbing or word splitting" advice.
+# We need word splitting for well-known variables like MAKEFLAGS and CFLAGS.
+disable=SC2086,SC2206

ci/LICENSE_MIT.txt

@@ -0,0 +1,19 @@
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

ci/README.md

@@ -0,0 +1,25 @@
+Scripts for the Continuous Integration of the PNG Reference Library
+===================================================================
+
+Copyright Notice
+----------------
+
+Copyright (c) 2019-2025 Cosmin Truta.
+
+Use, modification and distribution are subject to the MIT License.
+Please see the accompanying file `LICENSE_MIT.txt` or visit
+https://opensource.org/license/mit
+
+File List
+---------
+
+    LICENSE_MIT.txt         ==>  The License file
+    README.md               ==>  This file
+    ci_lint.sh              ==>  Lint the source code
+    ci_shellify.sh          ==>  Convert select definitions to shell syntax
+    ci_verify_cmake.sh      ==>  Verify the build driven by CMakeLists.txt
+    ci_verify_configure.sh  ==>  Verify the build driven by configure
+    ci_verify_makefiles.sh  ==>  Verify the build driven by scripts/makefile.*
+    ci_verify_version.sh    ==>  Verify the consistency of version definitions
+    lib/ci.lib.sh           ==>  Shell utilities for the main ci_*.sh scripts
+    targets/*/ci_env.*.sh   ==>  Shell environments for cross-platform testing

ci/ci_lint.sh

@@ -0,0 +1,142 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+# Initialize the global constants CI_{...}{CHECK,CHECKER,LINT}.
+CI_SHELLCHECK="${CI_SHELLCHECK:-shellcheck}"
+CI_EDITORCONFIG_CHECKER="${CI_EDITORCONFIG_CHECKER:-editorconfig-checker}"
+CI_YAMLLINT="${CI_YAMLLINT:-yamllint}"
+
+# Initialize the global lint status.
+CI_LINT_STATUS=0
+
+function ci_init_lint {
+    ci_info "## START OF LINTING ##"
+    local my_program
+    # Complete the initialization of CI_SHELLCHECK.
+    # Set it to the empty string if the shellcheck program is unavailable.
+    my_program="$(command -v "$CI_SHELLCHECK")" || {
+        ci_warn "program not found: '$CI_SHELLCHECK'"
+    }
+    CI_SHELLCHECK="$my_program"
+    # Complete the initialization of CI_EDITORCONFIG_CHECKER.
+    # Set it to the empty string if the editorconfig-checker program is unavailable.
+    my_program="$(command -v "$CI_EDITORCONFIG_CHECKER")" || {
+        ci_warn "program not found: '$CI_EDITORCONFIG_CHECKER'"
+    }
+    CI_EDITORCONFIG_CHECKER="$my_program"
+    # Complete the initialization of CI_YAMLLINT.
+    # Set it to the empty string if the yamllint program is unavailable.
+    my_program="$(command -v "$CI_YAMLLINT")" || {
+        ci_warn "program not found: '$CI_YAMLLINT'"
+    }
+    CI_YAMLLINT="$my_program"
+}
+
+function ci_finish_lint {
+    ci_info "## END OF LINTING ##"
+    if [[ $CI_LINT_STATUS -eq 0 ]]
+    then
+        ci_info "## SUCCESS ##"
+    else
+        ci_info "linting failed"
+    fi
+    return "$CI_LINT_STATUS"
+}
+
+function ci_lint_ci_scripts {
+    [[ -x $CI_SHELLCHECK ]] || {
+        ci_warn "## NOT LINTING: CI scripts ##"
+        return 0
+    }
+    ci_info "## LINTING: CI scripts ##"
+    ci_spawn "$CI_SHELLCHECK" --version
+    find ./ci -name "ci_*.sh" -not -name "ci_env.*.sh" | {
+        local my_file
+        while IFS="" read -r my_file
+        do
+            ci_spawn "$CI_SHELLCHECK" -x "$my_file" || {
+                # Linting failed.
+                return 1
+            }
+        done
+    }
+}
+
+function ci_lint_text_files {
+    [[ -x $CI_EDITORCONFIG_CHECKER ]] || {
+        ci_warn "## NOT LINTING: text files ##"
+        return 0
+    }
+    ci_info "## LINTING: text files ##"
+    ci_spawn "$CI_EDITORCONFIG_CHECKER" --version
+    ci_spawn "$CI_EDITORCONFIG_CHECKER" --config .editorconfig-checker.json || {
+        # Linting failed.
+        return 1
+    }
+}
+
+function ci_lint_yaml_files {
+    [[ -x $CI_YAMLLINT ]] || {
+        ci_warn "## NOT LINTING: YAML files ##"
+        return 0
+    }
+    ci_info "## LINTING: YAML files ##"
+    ci_spawn "$CI_YAMLLINT" --version
+    # Considering that the YAML format is an extension of the JSON format,
+    # we can lint both the YAML files and the plain JSON files here.
+    find . \( -iname "*.yml" -o -iname "*.yaml" -o -iname "*.json" \) -not -path "./out/*" | {
+        local my_file
+        while IFS="" read -r my_file
+        do
+            ci_spawn "$CI_YAMLLINT" --strict "$my_file" || {
+                # Linting failed.
+                return 1
+            }
+        done
+    }
+}
+
+function ci_lint {
+    ci_init_lint
+    ci_lint_ci_scripts || CI_LINT_STATUS=1
+    ci_lint_text_files || CI_LINT_STATUS=1
+    ci_lint_yaml_files || CI_LINT_STATUS=1
+    # TODO: ci_lint_png_files, etc.
+    ci_finish_lint
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        usage 2
+    }
+    # And... go!
+    ci_lint
+}
+
+main "$@"

ci/ci_verify_cmake.sh

@@ -0,0 +1,209 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+CI_SRC_DIR="$CI_TOPLEVEL_DIR"
+CI_OUT_DIR="$CI_TOPLEVEL_DIR/out"
+CI_BUILD_DIR="$CI_OUT_DIR/ci_verify_cmake.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.build"
+CI_INSTALL_DIR="$CI_OUT_DIR/ci_verify_cmake.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.install"
+
+function ci_init_build {
+    # Ensure that the mandatory variables are initialized.
+    CI_CMAKE="${CI_CMAKE:-cmake}"
+    CI_CTEST="${CI_CTEST:-ctest}"
+    CI_CMAKE_BUILD_TYPE="${CI_CMAKE_BUILD_TYPE:-Release}"
+    if [[ $CI_CMAKE_GENERATOR == "Visual Studio"* ]]
+    then
+        # Clean up incidental mixtures of Windows and Bash-on-Windows
+        # environment variables, to avoid confusing MSBuild.
+        [[ $TEMP && ( $Temp || $temp ) ]] && unset TEMP
+        [[ $TMP && ( $Tmp || $tmp ) ]] && unset TMP
+        # Ensure that CI_CMAKE_GENERATOR_PLATFORM is initialized for this generator.
+        [[ $CI_CMAKE_GENERATOR_PLATFORM ]] || {
+            ci_err_internal "missing \$CI_CMAKE_GENERATOR_PLATFORM"
+        }
+    elif [[ -x $(command -v ninja) ]]
+    then
+        CI_CMAKE_GENERATOR="${CI_CMAKE_GENERATOR:-Ninja}"
+    fi
+}
+
+function ci_trace_build {
+    ci_info "## START OF CONFIGURATION ##"
+    ci_info "build arch: $CI_BUILD_ARCH"
+    ci_info "build system: $CI_BUILD_SYSTEM"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] && {
+        ci_info "target arch: $CI_TARGET_ARCH"
+        ci_info "target system: $CI_TARGET_SYSTEM"
+    }
+    ci_info "source directory: $CI_SRC_DIR"
+    ci_info "build directory: $CI_BUILD_DIR"
+    ci_info "install directory: $CI_INSTALL_DIR"
+    ci_info "environment option: \$CI_CMAKE: '$CI_CMAKE'"
+    ci_info "environment option: \$CI_CMAKE_GENERATOR: '$CI_CMAKE_GENERATOR'"
+    ci_info "environment option: \$CI_CMAKE_GENERATOR_PLATFORM: '$CI_CMAKE_GENERATOR_PLATFORM'"
+    ci_info "environment option: \$CI_CMAKE_BUILD_TYPE: '$CI_CMAKE_BUILD_TYPE'"
+    ci_info "environment option: \$CI_CMAKE_BUILD_FLAGS: '$CI_CMAKE_BUILD_FLAGS'"
+    ci_info "environment option: \$CI_CMAKE_TOOLCHAIN_FILE: '$CI_CMAKE_TOOLCHAIN_FILE'"
+    ci_info "environment option: \$CI_CMAKE_VARS: '$CI_CMAKE_VARS'"
+    ci_info "environment option: \$CI_CTEST: '$CI_CTEST'"
+    ci_info "environment option: \$CI_CTEST_FLAGS: '$CI_CTEST_FLAGS'"
+    ci_info "environment option: \$CI_CC: '$CI_CC'"
+    ci_info "environment option: \$CI_CC_FLAGS: '$CI_CC_FLAGS'"
+    ci_info "environment option: \$CI_AR: '$CI_AR'"
+    ci_info "environment option: \$CI_RANLIB: '$CI_RANLIB'"
+    ci_info "environment option: \$CI_SANITIZERS: '$CI_SANITIZERS'"
+    ci_info "environment option: \$CI_FORCE: '$CI_FORCE'"
+    ci_info "environment option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+    ci_info "environment option: \$CI_NO_TEST: '$CI_NO_TEST'"
+    ci_info "environment option: \$CI_NO_INSTALL: '$CI_NO_INSTALL'"
+    ci_info "environment option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+    ci_info "executable: \$CI_CMAKE: $(command -V "$CI_CMAKE")"
+    ci_info "executable: \$CI_CTEST: $(command -V "$CI_CTEST")"
+    [[ $CI_CC ]] && {
+        ci_info "executable: \$CI_CC: $(command -V "$CI_CC")"
+    }
+    [[ $CI_AR ]] && {
+        ci_info "executable: \$CI_AR: $(command -V "$CI_AR")"
+    }
+    [[ $CI_RANLIB ]] && {
+        ci_info "executable: \$CI_RANLIB: $(command -V "$CI_RANLIB")"
+    }
+    ci_info "## END OF CONFIGURATION ##"
+}
+
+function ci_cleanup_old_build {
+    ci_info "## START OF PRE-BUILD CLEANUP ##"
+    [[ ! -e $CI_BUILD_DIR && ! -e $CI_INSTALL_DIR ]] || {
+        ci_spawn rm -fr "$CI_BUILD_DIR"
+        ci_spawn rm -fr "$CI_INSTALL_DIR"
+    }
+    ci_info "## END OF PRE-BUILD CLEANUP ##"
+}
+
+function ci_build {
+    ci_info "## START OF BUILD ##"
+    # Adjust the CI environment variables, as needed.
+    CI_CMAKE="$(command -v "$CI_CMAKE")" || ci_err "bad or missing \$CI_CMAKE"
+    ci_spawn "$CI_CMAKE" --version
+    CI_CTEST="$(command -v "$CI_CTEST")" || ci_err "bad or missing \$CI_CTEST"
+    ci_spawn "$CI_CTEST" --version
+    [[ $CI_CMAKE_GENERATOR == *"Ninja"* ]] && {
+        CI_NINJA="$(command -v ninja)" || ci_err "bad or missing ninja, no pun intended"
+        ci_spawn "$CI_NINJA" --version
+    }
+    [[ $CI_AR ]] && {
+        # Use the full path of CI_AR to work around a mysterious CMake error.
+        CI_AR="$(command -v "$CI_AR")" || ci_err "bad or missing \$CI_AR"
+    }
+    [[ $CI_RANLIB ]] && {
+        # Use the full path of CI_RANLIB to work around a mysterious CMake error.
+        CI_RANLIB="$(command -v "$CI_RANLIB")" || ci_err "bad or missing \$CI_RANLIB"
+    }
+    # Export the CMake environment variables.
+    [[ $CI_CMAKE_GENERATOR ]] && {
+        ci_spawn export CMAKE_GENERATOR="$CI_CMAKE_GENERATOR"
+    }
+    [[ $CI_CMAKE_GENERATOR_PLATFORM ]] && {
+        ci_spawn export CMAKE_GENERATOR_PLATFORM="$CI_CMAKE_GENERATOR_PLATFORM"
+    }
+    # Initialize and populate the local arrays.
+    local all_cmake_vars=()
+    local all_cmake_build_flags=()
+    local all_ctest_flags=()
+    [[ $CI_CMAKE_TOOLCHAIN_FILE ]] && {
+        all_cmake_vars+=("-DCMAKE_TOOLCHAIN_FILE=$CI_CMAKE_TOOLCHAIN_FILE")
+    }
+    [[ $CI_CC ]] && {
+        all_cmake_vars+=("-DCMAKE_C_COMPILER=$CI_CC")
+    }
+    [[ $CI_CC_FLAGS || $CI_SANITIZERS ]] && {
+        [[ $CI_SANITIZERS ]] && CI_CC_FLAGS+="${CI_CC_FLAGS:+" "}-fsanitize=$CI_SANITIZERS"
+        all_cmake_vars+=("-DCMAKE_C_FLAGS=$CI_CC_FLAGS")
+    }
+    [[ $CI_AR ]] && {
+        all_cmake_vars+=("-DCMAKE_AR=$CI_AR")
+    }
+    [[ $CI_RANLIB ]] && {
+        all_cmake_vars+=("-DCMAKE_RANLIB=$CI_RANLIB")
+    }
+    all_cmake_vars+=("-DCMAKE_BUILD_TYPE=$CI_CMAKE_BUILD_TYPE")
+    all_cmake_vars+=("-DCMAKE_VERBOSE_MAKEFILE=ON")
+    all_cmake_vars+=($CI_CMAKE_VARS)
+    all_cmake_build_flags+=($CI_CMAKE_BUILD_FLAGS)
+    all_ctest_flags+=($CI_CTEST_FLAGS)
+    # And... build!
+    ci_spawn mkdir -p "$CI_BUILD_DIR"
+    # Spawn "cmake ...".
+    ci_spawn "$CI_CMAKE" -B "$CI_BUILD_DIR" \
+                         -S . \
+                         -DCMAKE_INSTALL_PREFIX="$CI_INSTALL_DIR" \
+                         "${all_cmake_vars[@]}"
+    ci_expr $((CI_NO_BUILD)) || {
+        # Spawn "cmake --build ...".
+        ci_spawn "$CI_CMAKE" --build "$CI_BUILD_DIR" \
+                             --config "$CI_CMAKE_BUILD_TYPE" \
+                             "${all_cmake_build_flags[@]}"
+    }
+    ci_expr $((CI_NO_TEST)) || {
+        # Spawn "ctest" if testing is not disabled.
+        ci_spawn pushd "$CI_BUILD_DIR"
+        ci_spawn "$CI_CTEST" --build-config "$CI_CMAKE_BUILD_TYPE" \
+                             "${all_ctest_flags[@]}"
+        ci_spawn popd
+    }
+    ci_expr $((CI_NO_INSTALL)) || {
+        # Spawn "cmake --build ... --target install" if installation is not disabled.
+        ci_spawn "$CI_CMAKE" --build "$CI_BUILD_DIR" \
+                             --config "$CI_CMAKE_BUILD_TYPE" \
+                             --target install \
+                             "${all_cmake_build_flags[@]}"
+    }
+    ci_expr $((CI_NO_CLEAN)) || {
+        # Spawn "make --build ... --target clean" if cleaning is not disabled.
+        ci_spawn "$CI_CMAKE" --build "$CI_BUILD_DIR" \
+                             --config "$CI_CMAKE_BUILD_TYPE" \
+                             --target clean \
+                             "${all_cmake_build_flags[@]}"
+    }
+    ci_info "## END OF BUILD ##"
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
+    ci_init_build
+    ci_trace_build
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        echo >&2 "note: this program accepts environment options only"
+        usage 2
+    }
+    ci_cleanup_old_build
+    ci_build
+}
+
+main "$@"

ci/ci_verify_configure.sh

@@ -0,0 +1,182 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+CI_SRC_DIR="$CI_TOPLEVEL_DIR"
+CI_OUT_DIR="$CI_TOPLEVEL_DIR/out"
+CI_BUILD_DIR="$CI_OUT_DIR/ci_verify_configure.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.build"
+CI_INSTALL_DIR="$CI_OUT_DIR/ci_verify_configure.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.install"
+
+function ci_init_build {
+    # Ensure that the mandatory variables are initialized.
+    CI_MAKE="${CI_MAKE:-make}"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] || {
+        # For native builds, set CI_CC to "cc" by default if the cc command is available.
+        # The configure script defaults CC to "gcc", which is not always a good idea.
+        [[ -x $(command -v cc) ]] && CI_CC="${CI_CC:-cc}"
+    }
+    # Ensure that the CI_ variables that cannot be customized reliably are not initialized.
+    [[ ! $CI_CONFIGURE_VARS ]] || {
+        ci_err "unsupported: \$CI_CONFIGURE_VARS='$CI_CONFIGURE_VARS'"
+    }
+    [[ ! $CI_MAKE_VARS ]] || {
+        ci_err "unsupported: \$CI_MAKE_VARS='$CI_MAKE_VARS'"
+    }
+}
+
+function ci_trace_build {
+    ci_info "## START OF CONFIGURATION ##"
+    ci_info "build arch: $CI_BUILD_ARCH"
+    ci_info "build system: $CI_BUILD_SYSTEM"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] && {
+        ci_info "target arch: $CI_TARGET_ARCH"
+        ci_info "target system: $CI_TARGET_SYSTEM"
+    }
+    ci_info "source directory: $CI_SRC_DIR"
+    ci_info "build directory: $CI_BUILD_DIR"
+    ci_info "install directory: $CI_INSTALL_DIR"
+    ci_info "environment option: \$CI_CONFIGURE_FLAGS: '$CI_CONFIGURE_FLAGS'"
+    ci_info "environment option: \$CI_MAKE: '$CI_MAKE'"
+    ci_info "environment option: \$CI_MAKE_FLAGS: '$CI_MAKE_FLAGS'"
+    ci_info "environment option: \$CI_CC: '$CI_CC'"
+    ci_info "environment option: \$CI_CC_FLAGS: '$CI_CC_FLAGS'"
+    ci_info "environment option: \$CI_CPP: '$CI_CPP'"
+    ci_info "environment option: \$CI_CPP_FLAGS: '$CI_CPP_FLAGS'"
+    ci_info "environment option: \$CI_AR: '$CI_AR'"
+    ci_info "environment option: \$CI_RANLIB: '$CI_RANLIB'"
+    ci_info "environment option: \$CI_LD: '$CI_LD'"
+    ci_info "environment option: \$CI_LD_FLAGS: '$CI_LD_FLAGS'"
+    ci_info "environment option: \$CI_SANITIZERS: '$CI_SANITIZERS'"
+    ci_info "environment option: \$CI_FORCE: '$CI_FORCE'"
+    ci_info "environment option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+    ci_info "environment option: \$CI_NO_TEST: '$CI_NO_TEST'"
+    ci_info "environment option: \$CI_NO_INSTALL: '$CI_NO_INSTALL'"
+    ci_info "environment option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+    ci_info "executable: \$CI_MAKE: $(command -V "$CI_MAKE")"
+    [[ $CI_CC ]] && {
+        ci_info "executable: \$CI_CC: $(command -V "$CI_CC")"
+    }
+    [[ $CI_CPP ]] && {
+        ci_info "executable: \$CI_CPP: $(command -V "$CI_CPP")"
+    }
+    [[ $CI_AR ]] && {
+        ci_info "executable: \$CI_AR: $(command -V "$CI_AR")"
+    }
+    [[ $CI_RANLIB ]] && {
+        ci_info "executable: \$CI_RANLIB: $(command -V "$CI_RANLIB")"
+    }
+    [[ $CI_LD ]] && {
+        ci_info "executable: \$CI_LD: $(command -V "$CI_LD")"
+    }
+    ci_info "## END OF CONFIGURATION ##"
+}
+
+function ci_cleanup_old_build {
+    ci_info "## START OF PRE-BUILD CLEANUP ##"
+    [[ ! -e $CI_BUILD_DIR && ! -e $CI_INSTALL_DIR ]] || {
+        ci_spawn rm -fr "$CI_BUILD_DIR"
+        ci_spawn rm -fr "$CI_INSTALL_DIR"
+    }
+    [[ ! -e "$CI_SRC_DIR/config.status" ]] || {
+        ci_warn "unexpected build configuration file: '$CI_SRC_DIR/config.status'"
+        if ci_expr $((CI_FORCE))
+        then
+            # Delete the old config and (possibly) the old build.
+            ci_info "note: forcing an in-tree build cleanup"
+            if [[ -f $CI_SRC_DIR/Makefile ]]
+            then
+                ci_spawn make -C "$CI_SRC_DIR" distclean
+            else
+                ci_spawn rm -fr "$CI_SRC_DIR"/config.{log,status}
+            fi
+        else
+            # Alert the user, but do not delete their files.
+            ci_warn "the configure script might fail"
+            ci_info "hint: consider using the option \$CI_FORCE=1"
+        fi
+    }
+    ci_info "## END OF PRE-BUILD CLEANUP ##"
+}
+
+function ci_build {
+    ci_info "## START OF BUILD ##"
+    # Export the configure build environment.
+    [[ $CI_CC ]] && ci_spawn export CC="$CI_CC"
+    [[ $CI_CC_FLAGS ]] && ci_spawn export CFLAGS="$CI_CC_FLAGS"
+    [[ $CI_CPP ]] && ci_spawn export CPP="$CI_CPP"
+    [[ $CI_CPP_FLAGS ]] && ci_spawn export CPPFLAGS="$CI_CPP_FLAGS"
+    [[ $CI_AR ]] && ci_spawn export AR="$CI_AR"
+    [[ $CI_RANLIB ]] && ci_spawn export RANLIB="$CI_RANLIB"
+    [[ $CI_LD ]] && ci_spawn export LD="$CI_LD"
+    [[ $CI_LD_FLAGS ]] && ci_spawn export LDFLAGS="$CI_LD_FLAGS"
+    [[ $CI_SANITIZERS ]] && {
+        ci_spawn export CFLAGS="${CFLAGS:-"-O2"} -fsanitize=$CI_SANITIZERS"
+        ci_spawn export LDFLAGS="${LDFLAGS}${LDFLAGS:+" "}-fsanitize=$CI_SANITIZERS"
+    }
+    # Spawn "autogen.sh" if the configure script is not available.
+    [[ -x "$CI_SRC_DIR/configure" ]] || {
+        ci_spawn "$CI_SRC_DIR/autogen.sh" --maintainer
+    }
+    # And... build!
+    ci_spawn mkdir -p "$CI_BUILD_DIR"
+    ci_spawn cd "$CI_BUILD_DIR"
+    # Spawn "configure".
+    ci_spawn "$CI_SRC_DIR/configure" --prefix="$CI_INSTALL_DIR" $CI_CONFIGURE_FLAGS
+    ci_expr $((CI_NO_BUILD)) || {
+        # Spawn "make".
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS
+    }
+    ci_expr $((CI_NO_TEST)) || {
+        # Spawn "make test" if testing is not disabled.
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS test
+    }
+    ci_expr $((CI_NO_INSTALL)) || {
+        # Spawn "make install" if installation is not disabled.
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS install
+    }
+    ci_expr $((CI_NO_CLEAN)) || {
+        # Spawn "make clean" and "make distclean" if cleaning is not disabled.
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS clean
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS distclean
+    }
+    ci_info "## END OF BUILD ##"
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
+    ci_init_build
+    ci_trace_build
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        echo >&2 "note: this program accepts environment options only"
+        usage 2
+    }
+    ci_cleanup_old_build
+    ci_build
+}
+
+main "$@"

ci/ci_verify_makefiles.sh

@@ -0,0 +1,200 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+CI_SRC_DIR="$CI_TOPLEVEL_DIR"
+
+function ci_init_build {
+    # Ensure that the mandatory variables are initialized.
+    CI_MAKE="${CI_MAKE:-make}"
+    case "$CI_CC" in
+    ( *clang* )
+        CI_MAKEFILES="${CI_MAKEFILES:-"scripts/makefile.clang"}" ;;
+    ( *gcc* )
+        CI_MAKEFILES="${CI_MAKEFILES:-"scripts/makefile.gcc"}" ;;
+    ( * )
+        CI_MAKEFILES="${CI_MAKEFILES:-"scripts/makefile.std"}" ;;
+    esac
+}
+
+function ci_trace_build {
+    ci_info "## START OF CONFIGURATION ##"
+    ci_info "build arch: $CI_BUILD_ARCH"
+    ci_info "build system: $CI_BUILD_SYSTEM"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] && {
+        ci_info "target arch: $CI_TARGET_ARCH"
+        ci_info "target system: $CI_TARGET_SYSTEM"
+    }
+    ci_info "source directory: $CI_SRC_DIR"
+    ci_info "environment option: \$CI_MAKEFILES: '$CI_MAKEFILES'"
+    ci_info "environment option: \$CI_MAKE: '$CI_MAKE'"
+    ci_info "environment option: \$CI_MAKE_FLAGS: '$CI_MAKE_FLAGS'"
+    ci_info "environment option: \$CI_MAKE_VARS: '$CI_MAKE_VARS'"
+    ci_info "environment option: \$CI_CC: '$CI_CC'"
+    ci_info "environment option: \$CI_CC_FLAGS: '$CI_CC_FLAGS'"
+    ci_info "environment option: \$CI_CPP: '$CI_CPP'"
+    ci_info "environment option: \$CI_CPP_FLAGS: '$CI_CPP_FLAGS'"
+    ci_info "environment option: \$CI_AR: '$CI_AR'"
+    ci_info "environment option: \$CI_RANLIB: '$CI_RANLIB'"
+    ci_info "environment option: \$CI_LD: '$CI_LD'"
+    ci_info "environment option: \$CI_LD_FLAGS: '$CI_LD_FLAGS'"
+    ci_info "environment option: \$CI_LIBS: '$CI_LIBS'"
+    ci_info "environment option: \$CI_SANITIZERS: '$CI_SANITIZERS'"
+    ci_info "environment option: \$CI_FORCE: '$CI_FORCE'"
+    ci_info "environment option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+    ci_info "environment option: \$CI_NO_TEST: '$CI_NO_TEST'"
+    ci_info "environment option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+    ci_info "executable: \$CI_MAKE: $(command -V "$CI_MAKE")"
+    [[ $CI_CC ]] && {
+        ci_info "executable: \$CI_CC: $(command -V "$CI_CC")"
+    }
+    [[ $CI_CPP ]] && {
+        ci_info "executable: \$CI_CPP: $(command -V "$CI_CPP")"
+    }
+    [[ $CI_AR ]] && {
+        ci_info "executable: \$CI_AR: $(command -V "$CI_AR")"
+    }
+    [[ $CI_RANLIB ]] && {
+        ci_info "executable: \$CI_RANLIB: $(command -V "$CI_RANLIB")"
+    }
+    [[ $CI_LD ]] && {
+        ci_info "executable: \$CI_LD: $(command -V "$CI_LD")"
+    }
+    ci_info "## END OF CONFIGURATION ##"
+}
+
+function ci_cleanup_old_build {
+    # Any old makefile-based build will most likely leave a mess
+    # of object files behind if interrupted, e.g., via Ctrl+C.
+    # There may be other files behind, depending on what makefile
+    # had been used. We cannot easily enumerate all of those.
+    # Fortunately, for a clean makefiles-based build, it should be
+    # sufficient to remove the old object files only.
+    ci_info "## START OF PRE-BUILD CLEANUP ##"
+    local find_args=(-maxdepth 1 \( -iname "*.o" -o -iname "*.obj" \))
+    [[ ! $(find "$CI_SRC_DIR" "${find_args[@]}" | head -n1) ]] || {
+        ci_warn "unexpected build found in '$CI_SRC_DIR'"
+        if ci_expr $((CI_FORCE))
+        then
+            # Delete the old build.
+            local my_file
+            find "$CI_SRC_DIR" "${find_args[@]}" |
+                while IFS="" read -r my_file
+                do
+                    ci_spawn rm -fr "$my_file"
+                done
+            ci_info "## END OF PRE-BUILD CLEANUP ##"
+        else
+            # Alert the user, but do not delete their existing files,
+            # and do not mess up their existing build.
+            ci_info "hint: consider using the option \$CI_FORCE=1"
+            ci_err "unable to continue"
+        fi
+    }
+}
+
+function ci_build {
+    ci_info "## START OF BUILD ##"
+    # Initialize and populate the local arrays.
+    local all_make_flags=()
+    local all_make_vars=()
+    [[ $CI_MAKE_FLAGS ]] && {
+        all_make_flags+=($CI_MAKE_FLAGS)
+    }
+    [[ $CI_CC ]] && {
+        all_make_vars+=("CC=$CI_CC")
+    }
+    [[ $CI_CC_FLAGS || $CI_SANITIZERS ]] && {
+        [[ $CI_SANITIZERS ]] && CI_CC_FLAGS="${CI_CC_FLAGS:-"-O2"} -fsanitize=$CI_SANITIZERS"
+        all_make_vars+=("CFLAGS=$CI_CC_FLAGS")
+    }
+    [[ $CI_CPP ]] && {
+        all_make_vars+=("CPP=$CI_CPP")
+    }
+    [[ $CI_CPP_FLAGS ]] && {
+        all_make_vars+=("CPPFLAGS=$CI_CPP_FLAGS")
+    }
+    [[ $CI_AR ]] && {
+        all_make_vars+=("AR=$CI_AR")
+    }
+    [[ $CI_RANLIB ]] && {
+        all_make_vars+=("RANLIB=$CI_RANLIB")
+    }
+    [[ $CI_LD ]] && {
+        all_make_vars+=("LD=$CI_LD")
+    }
+    [[ $CI_LD_FLAGS || $CI_SANITIZERS ]] && {
+        [[ $CI_SANITIZERS ]] && CI_LD_FLAGS+="${CI_LD_FLAGS:+" "}-fsanitize=$CI_SANITIZERS"
+        all_make_vars+=("LDFLAGS=$CI_LD_FLAGS")
+    }
+    [[ $CI_LIBS ]] && {
+        all_make_vars+=("LIBS=$CI_LIBS")
+    }
+    all_make_vars+=($CI_MAKE_VARS)
+    # And... build!
+    local my_makefile
+    for my_makefile in $CI_MAKEFILES
+    do
+        ci_info "using makefile: $my_makefile"
+        ci_expr $((CI_NO_BUILD)) || {
+            # Spawn "make".
+            ci_spawn "$CI_MAKE" -f "$my_makefile" \
+                                "${all_make_flags[@]}" \
+                                "${all_make_vars[@]}"
+        }
+        ci_expr $((CI_NO_TEST)) || {
+            # Spawn "make test" if testing is not disabled.
+            ci_spawn "$CI_MAKE" -f "$my_makefile" \
+                                "${all_make_flags[@]}" \
+                                "${all_make_vars[@]}" \
+                                test
+        }
+        ci_expr $((CI_NO_CLEAN)) || {
+            # Spawn "make clean" if cleaning is not disabled.
+            ci_spawn "$CI_MAKE" -f "$my_makefile" \
+                                "${all_make_flags[@]}" \
+                                "${all_make_vars[@]}" \
+                                clean
+        }
+    done
+    ci_info "## END OF BUILD ##"
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
+    ci_init_build
+    ci_trace_build
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        echo >&2 "note: this program accepts environment options only"
+        usage 2
+    }
+    ci_cleanup_old_build
+    ci_build
+}
+
+main "$@"

ci/ci_verify_version.sh

@@ -0,0 +1,191 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+# Declare the global environments collected from various sources.
+declare CI_ENV_LIBPNG_VER        # collected from png.h
+declare CI_ENV_AUTOCONF_VER      # collected from configure.ac
+declare CI_ENV_CMAKE_VER         # collected from CMakeLists.txt
+declare CI_ENV_LIBPNGCONFIG_VER  # collected from scripts/libpng-config-head.in
+
+function ci_run_shellify {
+    local my_script my_result
+    my_script="$CI_SCRIPT_DIR/libexec/ci_shellify_${1#--}.sh"
+    shift 1
+    [[ -f $my_script ]] || {
+        ci_err_internal "missing script: '$my_script'"
+    }
+    ci_info "shellifying:" "$@"
+    "$BASH" "$my_script" "$@"
+    echo "$my_result" | "$BASH" --posix || ci_err "bad shellify output"
+    echo "$my_result"
+}
+
+function ci_init_version_verification {
+    ci_info "## START OF VERIFICATION ##"
+    CI_ENV_LIBPNG_VER="$(ci_run_shellify --c png.h)"
+    echo "$CI_ENV_LIBPNG_VER"
+    CI_ENV_AUTOCONF_VER="$(ci_run_shellify --autoconf configure.ac)"
+    echo "$CI_ENV_AUTOCONF_VER"
+    CI_ENV_CMAKE_VER="$(ci_run_shellify --cmake CMakeLists.txt)"
+    echo "$CI_ENV_CMAKE_VER"
+    CI_ENV_LIBPNGCONFIG_VER="$(ci_run_shellify --shell scripts/libpng-config-head.in)"
+    echo "$CI_ENV_LIBPNGCONFIG_VER"
+}
+
+# shellcheck disable=SC2154
+function ci_do_version_verification {
+    local my_expect
+    ci_info "## VERIFYING: version definitions in 'png.h' ##"
+    eval "$CI_ENV_LIBPNG_VER"
+    my_expect="${PNG_LIBPNG_VER_MAJOR}.${PNG_LIBPNG_VER_MINOR}.${PNG_LIBPNG_VER_RELEASE}"
+    if [[ "$PNG_LIBPNG_VER_STRING" == "$my_expect"* ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_STRING == $my_expect*"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_STRING != $my_expect*"
+    fi
+    my_expect=$((PNG_LIBPNG_VER_MAJOR*10000 + PNG_LIBPNG_VER_MINOR*100 + PNG_LIBPNG_VER_RELEASE))
+    if [[ "$PNG_LIBPNG_VER" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER != $my_expect"
+    fi
+    my_expect=$((PNG_LIBPNG_VER_MAJOR*10 + PNG_LIBPNG_VER_MINOR))
+    if [[ "$PNG_LIBPNG_VER_SHAREDLIB" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_SHAREDLIB == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_SHAREDLIB != $my_expect"
+    fi
+    if [[ "$PNG_LIBPNG_VER_SONUM" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_SONUM == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_SONUM != $my_expect"
+    fi
+    if [[ "$PNG_LIBPNG_VER_DLLNUM" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_DLLNUM == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_DLLNUM != $my_expect"
+    fi
+    if [[ "$PNG_LIBPNG_VER_BUILD" == [01] ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_BUILD == [01]"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_BUILD != [01]"
+    fi
+    ci_info "## VERIFYING: build definitions in 'png.h' ##"
+    my_expect="${PNG_LIBPNG_VER_MAJOR}.${PNG_LIBPNG_VER_MINOR}.${PNG_LIBPNG_VER_RELEASE}"
+    if [[ "$PNG_LIBPNG_VER_STRING" == "$my_expect" ]]
+    then
+        if [[ $PNG_LIBPNG_VER_BUILD -eq 0 ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_VER_BUILD -eq 0"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_VER_BUILD -ne 0"
+        fi
+        if [[ $PNG_LIBPNG_BUILD_BASE_TYPE -eq $PNG_LIBPNG_BUILD_STABLE ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_BUILD_BASE_TYPE -eq \$PNG_LIBPNG_BUILD_STABLE"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_BUILD_BASE_TYPE -ne \$PNG_LIBPNG_BUILD_STABLE"
+        fi
+    elif [[ "$PNG_LIBPNG_VER_STRING" == "$my_expect".git ]]
+    then
+        if [[ $PNG_LIBPNG_VER_BUILD -ne 0 ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_VER_BUILD -ne 0"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_VER_BUILD -eq 0"
+        fi
+        if [[ $PNG_LIBPNG_BUILD_BASE_TYPE -ne $PNG_LIBPNG_BUILD_STABLE ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_BUILD_BASE_TYPE -ne \$PNG_LIBPNG_BUILD_STABLE"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_BUILD_BASE_TYPE -eq \$PNG_LIBPNG_BUILD_STABLE"
+        fi
+    else
+        ci_err "unexpected: \$PNG_LIBPNG_VER_STRING == '$PNG_LIBPNG_VER_STRING'"
+    fi
+    ci_info "## VERIFYING: type definitions in 'png.h' ##"
+    my_expect="$(echo "png_libpng_version_${PNG_LIBPNG_VER_STRING}" | tr . _)"
+    ci_spawn grep -w -e "$my_expect" png.h
+    ci_info "## VERIFYING: version definitions in 'configure.ac' ##"
+    eval "$CI_ENV_AUTOCONF_VER"
+    if [[ "$PNGLIB_VERSION" == "$PNG_LIBPNG_VER_STRING" ]]
+    then
+        ci_info "matched: \$PNGLIB_VERSION == \$PNG_LIBPNG_VER_STRING"
+    else
+        ci_err "mismatched: \$PNGLIB_VERSION != \$PNG_LIBPNG_VER_STRING"
+    fi
+    ci_info "## VERIFYING: version definitions in 'CMakeLists.txt' ##"
+    eval "$CI_ENV_CMAKE_VER"
+    if [[ "$PNGLIB_VERSION" == "$PNG_LIBPNG_VER_STRING" && "$PNGLIB_SUBREVISION" == 0 ]]
+    then
+        ci_info "matched: \$PNGLIB_VERSION == \$PNG_LIBPNG_VER_STRING"
+        ci_info "matched: \$PNGLIB_SUBREVISION == 0"
+    elif [[ "$PNGLIB_VERSION.$PNGLIB_SUBREVISION" == "$PNG_LIBPNG_VER_STRING" ]]
+    then
+        ci_info "matched: \$PNGLIB_VERSION.\$PNGLIB_SUBREVISION == \$PNG_LIBPNG_VER_STRING"
+    else
+        ci_err "mismatched: \$PNGLIB_VERSION != \$PNG_LIBPNG_VER_STRING"
+    fi
+    ci_info "## VERIFYING: version definitions in 'scripts/libpng-config-head.in' ##"
+    eval "$CI_ENV_LIBPNGCONFIG_VER"
+    if [[ "$version" == "$PNG_LIBPNG_VER_STRING" ]]
+    then
+        ci_info "matched: \$version == \$PNG_LIBPNG_VER_STRING"
+    else
+        ci_err "mismatched: \$version != \$PNG_LIBPNG_VER_STRING"
+    fi
+}
+
+function ci_finish_version_verification {
+    ci_info "## END OF VERIFICATION ##"
+    # Relying on "set -o errexit" to not reach here in case of error.
+    ci_info "## SUCCESS ##"
+}
+
+function ci_verify_version {
+    ci_init_version_verification
+    ci_do_version_verification
+    ci_finish_version_verification
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        usage 2
+    }
+    # And... go!
+    ci_verify_version
+}
+
+main "$@"

ci/lib/ci.lib.sh

@@ -0,0 +1,111 @@
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+test -f "$BASH_SOURCE" || {
+    echo >&2 "warning: this module requires Bash version 3 or newer"
+}
+test "${#BASH_SOURCE[@]}" -gt 1 || {
+    echo >&2 "warning: this module should be sourced from a Bash script"
+}
+
+# Reset the locale to avoid surprises from locale-dependent commands.
+export LC_ALL=C
+export LANG=C
+export LANGUAGE=C
+
+# Reset CDPATH to avoid surprises from the "cd" command.
+export CDPATH=""
+
+# Initialize the global constants CI_SCRIPT_{NAME,DIR} and CI_TOPLEVEL_DIR.
+CI_SCRIPT_NAME="$(basename -- "$0")"
+CI_SCRIPT_DIR="$(cd "$(dirname -- "$0")" && pwd)"
+CI_TOPLEVEL_DIR="$(cd "$(dirname -- "${BASH_SOURCE[0]}")/../.." && pwd)"
+
+# Initialize the global constants CI_BUILD_{...} for the host build platform.
+CI_BUILD_ARCH="${CI_BUILD_ARCH:-"$(uname -m | tr 'A-Z/\.-' 'a-z____')"}"
+CI_BUILD_SYSTEM="${CI_BUILD_SYSTEM:-"$(uname -s | tr 'A-Z/\.-' 'a-z____')"}"
+
+# Initialize the global constants CI_TARGET_{...} for the target platform.
+CI_TARGET_ARCH="${CI_TARGET_ARCH:-"$CI_BUILD_ARCH"}"
+CI_TARGET_SYSTEM="${CI_TARGET_SYSTEM:-"$CI_BUILD_SYSTEM"}"
+
+function ci_info {
+    printf >&2 "%s: %s\\n" "$CI_SCRIPT_NAME" "$*"
+}
+
+function ci_warn {
+    printf >&2 "%s: warning: %s\\n" "$CI_SCRIPT_NAME" "$*"
+}
+
+function ci_err {
+    printf >&2 "%s: error: %s\\n" "$CI_SCRIPT_NAME" "$*"
+    exit 2
+}
+
+function ci_err_internal {
+    printf >&2 "%s: internal error: %s\\n" "$CI_SCRIPT_NAME" "$*"
+    printf >&2 "ABORTED\\n"
+    # Exit with the conventional SIGABRT code.
+    exit 134
+}
+
+function ci_expr {
+    if [[ ${*:-0} == [0-9] ]]
+    then
+        # This is the same as in the else-branch below, albeit much faster
+        # for our intended use cases.
+        return $((!$1))
+    else
+        # The funny-looking compound command "... && return $? || return $?"
+        # allows the execution to continue uninterrupted under "set -e".
+        expr >/dev/null "$@" && return $? || return $?
+    fi
+}
+
+function ci_spawn {
+    printf >&2 "%s: executing:" "$CI_SCRIPT_NAME"
+    printf >&2 " %q" "$@"
+    printf >&2 "\\n"
+    "$@"
+}
+
+# Ensure that the internal initialization is correct.
+[[ $CI_TOPLEVEL_DIR/ci/lib/ci.lib.sh -ef ${BASH_SOURCE[0]} ]] || {
+    ci_err_internal "bad or missing \$CI_TOPLEVEL_DIR"
+}
+[[ $CI_SCRIPT_DIR/$CI_SCRIPT_NAME -ef $0 ]] || {
+    ci_err_internal "bad or missing \$CI_SCRIPT_DIR/\$CI_SCRIPT_NAME"
+}
+[[ $CI_BUILD_ARCH && $CI_BUILD_SYSTEM ]] || {
+    ci_err_internal "missing \$CI_BUILD_ARCH or \$CI_BUILD_SYSTEM"
+}
+[[ $CI_TARGET_ARCH && $CI_TARGET_SYSTEM ]] || {
+    ci_err_internal "missing \$CI_TARGET_ARCH or \$CI_TARGET_SYSTEM"
+}
+
+# Ensure that the user initialization is correct.
+[[ ${CI_FORCE:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_FORCE: '$CI_FORCE'"
+}
+[[ ${CI_NO_BUILD:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+}
+[[ ${CI_NO_TEST:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_TEST: '$CI_NO_TEST'"
+}
+[[ ${CI_NO_INSTALL:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_INSTALL: '$CI_NO_INSTALL'"
+}
+[[ ${CI_NO_CLEAN:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+}
+if ci_expr $((CI_NO_BUILD))
+then
+    ci_expr $((CI_NO_TEST && CI_NO_INSTALL)) || {
+        ci_err "\$CI_NO_BUILD requires \$CI_NO_TEST and \$CI_NO_INSTALL"
+    }
+fi

ci/libexec/ci_shellify_autoconf.sh

@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_autoconf {
+    # Convert autoconf (M4) text, specifically originating
+    # from configure.ac, to shell scripting text.
+    # Select only the easy-to-parse definitions of PNGLIB_*.
+    sed -n -e '/^ *PNGLIB_[^ ]*=[$"0-9A-Za-z_]/ p' |
+        sed -e 's/^ *PNG\([0-9A-Za-z_]*\)=\([^# ]*\).*$/PNG\1=\2/' \
+            -e 's/^\([^ ]*=[^ ]*\).*$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] configure.ac"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    [[ $(basename -- "$1") == configure.ac ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'configure.ac')"
+    }
+    ci_shellify_autoconf <"$1"
+}
+
+main "$@"

ci/libexec/ci_shellify_c.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_c {
+    # Convert C preprocessor text, specifically originating
+    # from png.h, to shell scripting text.
+    # Select only the easy-to-parse definitions of PNG_LIBPNG_*.
+    sed -n -e '/^\# *define * PNG_LIBPNG_[^ ]* * ["0-9A-Za-z_]/ p' |
+        sed -e 's/^\# *define * PNG\([^ ]*\) * \([^ ]*\)/PNG\1=\2/' \
+            -e 's/=PNG\([0-9A-Za-z_]*\)/=\${PNG\1}/' \
+            -e 's/^\([^ ]*=[^ ]*\).*$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] png.h"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    [[ $(basename -- "$1") == png.h ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'png.h')"
+    }
+    ci_shellify_c <"$1"
+}
+
+main "$@"

ci/libexec/ci_shellify_cmake.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_cmake {
+    # Convert CMake lists text, specifically originating
+    # from CMakeLists.txt, to shell scripting text.
+    # Select only the easy-to-parse definitions of PNGLIB_*.
+    sed -n -e '/^ *set *(PNGLIB_[^ ]* * [$"0-9A-Za-z_].*)/ p' |
+        sed -e 's/^ *set *(PNG\([^ ]*\) * \([^() ]*\)).*$/PNG\1=\2/' \
+            -e 's/^\([^ ]*=[^ ]*\).*$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] CMakeLists.txt"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    filename="$(basename -- "$1")"
+    [[ $filename == [Cc][Mm]ake[Ll]ists.txt ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'CMakeLists.txt')"
+    }
+    ci_shellify_cmake <"$1"
+}
+
+main "$@"

ci/libexec/ci_shellify_shell.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_shell {
+    # Convert shell scripting text to shell scripting text.
+    # Select only the easy-to-parse version definitions.
+    sed -n -e '/^ *[A-Za-z_][0-9A-Za-z_]*=[0-9][^ #]* *$/ p' |
+        sed -e 's/^ *\([^ ]*=[^ ]*\) *$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] libpng-config-head.in"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    [[ $(basename -- "$1") == libpng-config-head.in ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'libpng-config-head.in')"
+    }
+    ci_shellify_shell <"$1"
+}
+
+main "$@"

ci/targets/android/ci_env.aarch64-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_ARCHVER=aarch64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.armv7a-linux-androideabi.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_ARCHVER=armv7a
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=androideabi
+export CI_TARGET_ABIVER=androideabi29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.i686-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_ARCHVER=i686
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.x86_64-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_ARCHVER=x86_64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/cygwin/ci_env.i686-pc-cygwin.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=cygwin
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=CYGWIN
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/cygwin/ci_env.x86_64-pc-cygwin.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=cygwin
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=CYGWIN
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/darwin/ci_env.arm64-apple-darwin.sh

@@ -0,0 +1,15 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm64
+export CI_TARGET_SYSTEM=darwin
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Darwin
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+    -DCMAKE_OSX_ARCHITECTURES=$CI_TARGET_ARCH
+"

ci/targets/darwin/ci_env.x86_64-apple-darwin.sh

@@ -0,0 +1,15 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=darwin
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Darwin
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+    -DCMAKE_OSX_ARCHITECTURES=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.aarch64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.i686-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.riscv64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=riscv64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.x86_64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.aarch64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.arm-linux-gnueabi.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnueabi
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.arm-linux-gnueabihf.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnueabihf
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.i686-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips64-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips64el-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips64el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsel-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsel
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa32r6-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa32r6
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa32r6el-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa32r6el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa64r6-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa64r6
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa64r6el-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa64r6el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc64le-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc64le
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.riscv64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=riscv64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.x86_64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/msdos/ci_env.i386-pc-msdoswatcom.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i386
+export CI_TARGET_SYSTEM=msdoswatcom
+
+export CI_CC="wcl386"
+
+# Open Watcom V2 CMake build
+# https://github.com/open-watcom/open-watcom-v2/discussions/716
+export CI_CMAKE_GENERATOR="Watcom WMake"
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=DOS
+"

ci/targets/msdos/ci_env.i586-pc-msdosdjgpp.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i586
+export CI_TARGET_SYSTEM=msdosdjgpp
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Generic
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/msdos/ci_env.i86-pc-msdoswatcom.sh

@@ -0,0 +1,19 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i86
+export CI_TARGET_SYSTEM=msdoswatcom
+
+export CI_CC="wcl"
+
+# Open Watcom V2 CMake build
+# https://github.com/open-watcom/open-watcom-v2/discussions/716
+export CI_CMAKE_GENERATOR="Watcom WMake"
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=DOS
+    -DCMAKE_SYSTEM_PROCESSOR=I86
+"

ci/targets/windows/ci_env.aarch64-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.i686-w64-mingw32.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=mingw32
+
+# The output of `uname -s` on MSYS2 is understandable, and so is
+# CI_TARGET_SYSTEM above, in simplified form. (See also Cygwin.)
+# But aside from that, the Mingw-w64 nomenclature is rather messy.
+export CI_CC="$CI_TARGET_ARCH-w64-mingw32-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.i686-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.x86_64-w64-mingw32.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=mingw64
+
+# The output of `uname -s` on MSYS2 is understandable, and so is
+# CI_TARGET_SYSTEM above, in simplified form. (See also Cygwin.)
+# But aside from that, the Mingw-w64 nomenclature is rather messy.
+export CI_CC="$CI_TARGET_ARCH-w64-mingw32-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.x86_64-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

compile

@@ -0,0 +1,364 @@
+#! /bin/sh
+# Wrapper for compilers which do not understand '-c -o'.
+
+scriptversion=2025-02-03.05; # UTC
+
+# Copyright (C) 1999-2025 Free Software Foundation, Inc.
+# Written by Tom Tromey <tromey@cygnus.com>.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+# As a special exception to the GNU General Public License, if you
+# distribute this file as part of a program that contains a
+# configuration script generated by Autoconf, you may include it under
+# the same distribution terms that you use for the rest of that program.
+
+# This file is maintained in Automake, please report
+# bugs to <bug-automake@gnu.org> or send patches to
+# <automake-patches@gnu.org>.
+
+nl='
+'
+
+# We need space, tab and new line, in precisely that order.  Quoting is
+# there to prevent tools from complaining about whitespace usage.
+IFS=" ""	$nl"
+
+file_conv=
+
+# func_file_conv build_file unneeded_conversions
+# Convert a $build file to $host form and store it in $file
+# Currently only supports Windows hosts. If the determined conversion
+# type is listed in (the comma separated) UNNEEDED_CONVERSIONS, no
+# conversion will take place.
+func_file_conv ()
+{
+  file=$1
+  case $file in
+    / | /[!/]*) # absolute file, and not a UNC file
+      if test -z "$file_conv"; then
+	# lazily determine how to convert abs files
+	case `uname -s` in
+	  MINGW*)
+	    if test -n "$MSYSTEM" && (cygpath --version) >/dev/null 2>&1; then
+	      # MSYS2 environment.
+	      file_conv=cygwin
+	    else
+	      # Original MinGW environment.
+	      file_conv=mingw
+	    fi
+	    ;;
+	  MSYS*)
+	    # Old MSYS environment, or MSYS2 with 32-bit MSYS2 shell.
+	    file_conv=cygwin
+	    ;;
+	  CYGWIN*)
+	    # Cygwin environment.
+	    file_conv=cygwin
+	    ;;
+	  *)
+	    file_conv=wine
+	    ;;
+	esac
+      fi
+      case $file_conv/,$2, in
+	*,$file_conv,*)
+	  # This is the optimization mentioned above:
+	  # If UNNEEDED_CONVERSIONS contains $file_conv, don't convert.
+	  ;;
+	mingw/*)
+	  file=`cmd //C echo "$file " | sed -e 's/"\(.*\) " *$/\1/'`
+	  ;;
+	cygwin/*)
+	  file=`cygpath -w "$file" || echo "$file"`
+	  ;;
+	wine/*)
+	  file=`winepath -w "$file" || echo "$file"`
+	  ;;
+      esac
+      ;;
+  esac
+}
+
+# func_cl_dashL linkdir
+# Make cl look for libraries in LINKDIR
+func_cl_dashL ()
+{
+  func_file_conv "$1"
+  if test -z "$lib_path"; then
+    lib_path=$file
+  else
+    lib_path="$lib_path;$file"
+  fi
+  linker_opts="$linker_opts -LIBPATH:$file"
+}
+
+# func_cl_dashl library
+# Do a library search-path lookup for cl
+func_cl_dashl ()
+{
+  lib=$1
+  found=no
+  save_IFS=$IFS
+  IFS=';'
+  for dir in $lib_path $LIB
+  do
+    IFS=$save_IFS
+    if $shared && test -f "$dir/$lib.dll.lib"; then
+      found=yes
+      lib=$dir/$lib.dll.lib
+      break
+    fi
+    if test -f "$dir/$lib.lib"; then
+      found=yes
+      lib=$dir/$lib.lib
+      break
+    fi
+    if test -f "$dir/lib$lib.a"; then
+      found=yes
+      lib=$dir/lib$lib.a
+      break
+    fi
+  done
+  IFS=$save_IFS
+
+  if test "$found" != yes; then
+    lib=$lib.lib
+  fi
+}
+
+# func_cl_wrapper cl arg...
+# Adjust compile command to suit cl
+func_cl_wrapper ()
+{
+  # Assume a capable shell
+  lib_path=
+  shared=:
+  linker_opts=
+  for arg
+  do
+    if test -n "$eat"; then
+      eat=
+    else
+      case $1 in
+	-o)
+	  # configure might choose to run compile as 'compile cc -o foo foo.c'.
+	  eat=1
+	  case $2 in
+	    *.o | *.lo | *.[oO][bB][jJ])
+	      func_file_conv "$2"
+	      set x "$@" -Fo"$file"
+	      shift
+	      ;;
+	    *)
+	      func_file_conv "$2"
+	      set x "$@" -Fe"$file"
+	      shift
+	      ;;
+	  esac
+	  ;;
+	-I)
+	  eat=1
+	  func_file_conv "$2" mingw
+	  set x "$@" -I"$file"
+	  shift
+	  ;;
+	-I*)
+	  func_file_conv "${1#-I}" mingw
+	  set x "$@" -I"$file"
+	  shift
+	  ;;
+	-l)
+	  eat=1
+	  func_cl_dashl "$2"
+	  set x "$@" "$lib"
+	  shift
+	  ;;
+	-l*)
+	  func_cl_dashl "${1#-l}"
+	  set x "$@" "$lib"
+	  shift
+	  ;;
+	-L)
+	  eat=1
+	  func_cl_dashL "$2"
+	  ;;
+	-L*)
+	  func_cl_dashL "${1#-L}"
+	  ;;
+	-static)
+	  shared=false
+	  ;;
+	-Wl,*)
+	  arg=${1#-Wl,}
+	  save_ifs="$IFS"; IFS=','
+	  for flag in $arg; do
+	    IFS="$save_ifs"
+	    linker_opts="$linker_opts $flag"
+	  done
+	  IFS="$save_ifs"
+	  ;;
+	-Xlinker)
+	  eat=1
+	  linker_opts="$linker_opts $2"
+	  ;;
+	-*)
+	  set x "$@" "$1"
+	  shift
+	  ;;
+	*.cc | *.CC | *.cxx | *.CXX | *.[cC]++)
+	  func_file_conv "$1"
+	  set x "$@" -Tp"$file"
+	  shift
+	  ;;
+	*.c | *.cpp | *.CPP | *.lib | *.LIB | *.Lib | *.OBJ | *.obj | *.[oO])
+	  func_file_conv "$1" mingw
+	  set x "$@" "$file"
+	  shift
+	  ;;
+	*)
+	  set x "$@" "$1"
+	  shift
+	  ;;
+      esac
+    fi
+    shift
+  done
+  if test -n "$linker_opts"; then
+    linker_opts="-link$linker_opts"
+  fi
+  exec "$@" $linker_opts
+  exit 1
+}
+
+eat=
+
+case $1 in
+  '')
+     echo "$0: No command.  Try '$0 --help' for more information." 1>&2
+     exit 1;
+     ;;
+  -h | --h*)
+    cat <<\EOF
+Usage: compile [--help] [--version] PROGRAM [ARGS]
+
+Wrapper for compilers which do not understand '-c -o'.
+Remove '-o dest.o' from ARGS, run PROGRAM with the remaining
+arguments, and rename the output as expected.
+
+If you are trying to build a whole package this is not the
+right script to run: please start by reading the file 'INSTALL'.
+
+Report bugs to <bug-automake@gnu.org>.
+GNU Automake home page: <https://www.gnu.org/software/automake/>.
+General help using GNU software: <https://www.gnu.org/gethelp/>.
+EOF
+    exit $?
+    ;;
+  -v | --v*)
+    echo "compile (GNU Automake) $scriptversion"
+    exit $?
+    ;;
+  cl | *[/\\]cl | cl.exe | *[/\\]cl.exe | \
+  clang-cl | *[/\\]clang-cl | clang-cl.exe | *[/\\]clang-cl.exe | \
+  icl | *[/\\]icl | icl.exe | *[/\\]icl.exe )
+    func_cl_wrapper "$@"      # Doesn't return...
+    ;;
+esac
+
+ofile=
+cfile=
+
+for arg
+do
+  if test -n "$eat"; then
+    eat=
+  else
+    case $1 in
+      -o)
+	# configure might choose to run compile as 'compile cc -o foo foo.c'.
+	# So we strip '-o arg' only if arg is an object.
+	eat=1
+	case $2 in
+	  *.o | *.obj)
+	    ofile=$2
+	    ;;
+	  *)
+	    set x "$@" -o "$2"
+	    shift
+	    ;;
+	esac
+	;;
+      *.c)
+	cfile=$1
+	set x "$@" "$1"
+	shift
+	;;
+      *)
+	set x "$@" "$1"
+	shift
+	;;
+    esac
+  fi
+  shift
+done
+
+if test -z "$ofile" || test -z "$cfile"; then
+  # If no '-o' option was seen then we might have been invoked from a
+  # pattern rule where we don't need one.  That is ok -- this is a
+  # normal compilation that the losing compiler can handle.  If no
+  # '.c' file was seen then we are probably linking.  That is also
+  # ok.
+  exec "$@"
+fi
+
+# Name of file we expect compiler to create.
+cofile=`echo "$cfile" | sed 's|^.*[\\/]||; s|^[a-zA-Z]:||; s/\.c$/.o/'`
+
+# Create the lock directory.
+# Note: use '[/\\:.-]' here to ensure that we don't use the same name
+# that we are using for the .o file.  Also, base the name on the expected
+# object file name, since that is what matters with a parallel build.
+lockdir=`echo "$cofile" | sed -e 's|[/\\:.-]|_|g'`.d
+while true; do
+  if mkdir "$lockdir" >/dev/null 2>&1; then
+    break
+  fi
+  sleep 1
+done
+# FIXME: race condition here if user kills between mkdir and trap.
+trap "rmdir '$lockdir'; exit 1" 1 2 15
+
+# Run the compile.
+"$@"
+ret=$?
+
+if test -f "$cofile"; then
+  test "$cofile" = "$ofile" || mv "$cofile" "$ofile"
+elif test -f "${cofile}bj"; then
+  test "${cofile}bj" = "$ofile" || mv "${cofile}bj" "$ofile"
+fi
+
+rmdir "$lockdir"
+exit $ret
+
+# Local Variables:
+# mode: shell-script
+# sh-indentation: 2
+# eval: (add-hook 'before-save-hook 'time-stamp nil t)
+# time-stamp-start: "scriptversion="
+# time-stamp-format: "%:y-%02m-%02d.%02H"
+# time-stamp-time-zone: "UTC0"
+# time-stamp-end: "; # UTC"
+# End:

config.h.in

@@ -0,0 +1,144 @@
+/* config.h.in.  Generated from configure.ac by autoheader.  */
+
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#undef HAVE_DLFCN_H
+
+/* Define to 1 if you have the 'feenableexcept' function. */
+#undef HAVE_FEENABLEEXCEPT
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#undef HAVE_INTTYPES_H
+
+/* Define to 1 if you have the 'm' library (-lm). */
+#undef HAVE_LIBM
+
+/* Define to 1 if you have the 'z' library (-lz). */
+#undef HAVE_LIBZ
+
+/* Define to 1 if you have the 'pow' function. */
+#undef HAVE_POW
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#undef HAVE_STDINT_H
+
+/* Define to 1 if you have the <stdio.h> header file. */
+#undef HAVE_STDIO_H
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#undef HAVE_STDLIB_H
+
+/* Define to 1 if you have the <strings.h> header file. */
+#undef HAVE_STRINGS_H
+
+/* Define to 1 if you have the <string.h> header file. */
+#undef HAVE_STRING_H
+
+/* Define to 1 if you have the <sys/stat.h> header file. */
+#undef HAVE_SYS_STAT_H
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#undef HAVE_SYS_TYPES_H
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#undef HAVE_UNISTD_H
+
+/* Define to the sub-directory where libtool stores uninstalled libraries. */
+#undef LT_OBJDIR
+
+/* Name of package */
+#undef PACKAGE
+
+/* Define to the address where bug reports for this package should be sent. */
+#undef PACKAGE_BUGREPORT
+
+/* Define to the full name of this package. */
+#undef PACKAGE_NAME
+
+/* Define to the full name and version of this package. */
+#undef PACKAGE_STRING
+
+/* Define to the one symbol short name of this package. */
+#undef PACKAGE_TARNAME
+
+/* Define to the home page for this package. */
+#undef PACKAGE_URL
+
+/* Define to the version of this package. */
+#undef PACKAGE_VERSION
+
+/* Turn on ARM Neon optimizations at run-time */
+#undef PNG_ARM_NEON_API_SUPPORTED
+
+/* Check for ARM Neon support at run-time */
+#undef PNG_ARM_NEON_CHECK_SUPPORTED
+
+/* Enable ARM Neon optimizations */
+#undef PNG_ARM_NEON_OPT
+
+/* Enable Intel SSE optimizations */
+#undef PNG_INTEL_SSE_OPT
+
+/* Enable LOONGARCH LSX optimizations */
+#undef PNG_LOONGARCH_LSX_OPT
+
+/* Turn on MIPS MMI optimizations at run-time */
+#undef PNG_MIPS_MMI_API_SUPPORTED
+
+/* Check for MIPS MMI support at run-time */
+#undef PNG_MIPS_MMI_CHECK_SUPPORTED
+
+/* Enable MIPS MMI optimizations */
+#undef PNG_MIPS_MMI_OPT
+
+/* Turn on MIPS MSA optimizations at run-time */
+#undef PNG_MIPS_MSA_API_SUPPORTED
+
+/* Check for MIPS MSA support at run-time */
+#undef PNG_MIPS_MSA_CHECK_SUPPORTED
+
+/* Enable MIPS MSA optimizations */
+#undef PNG_MIPS_MSA_OPT
+
+/* Turn on POWERPC VSX optimizations at run-time */
+#undef PNG_POWERPC_VSX_API_SUPPORTED
+
+/* Check for POWERPC VSX support at run-time */
+#undef PNG_POWERPC_VSX_CHECK_SUPPORTED
+
+/* Enable POWERPC VSX optimizations */
+#undef PNG_POWERPC_VSX_OPT
+
+/* Turn on RISC-V Vector optimizations at run-time */
+#undef PNG_RISCV_RVV_API_SUPPORTED
+
+/* Check for RISC-V Vector support at run-time */
+#undef PNG_RISCV_RVV_CHECK_SUPPORTED
+
+/* Enable RISCV RVV optimizations */
+#undef PNG_RISCV_RVV_OPT
+
+/* Define to 1 if all of the C89 standard headers exist (not just the ones
+   required in a freestanding environment). This macro is provided for
+   backward compatibility; new code need not use it. */
+#undef STDC_HEADERS
+
+/* Define to 1 if your <sys/time.h> declares 'struct tm'. */
+#undef TM_IN_SYS_TIME
+
+/* Version number of package */
+#undef VERSION
+
+/* Define to the equivalent of the C99 'restrict' keyword, or to
+   nothing if this is not supported.  Do not define if restrict is
+   supported only directly.  */
+#undef restrict
+/* Work around a bug in older versions of Sun C++, which did not
+   #define __restrict__ or support _Restrict or __restrict__
+   even though the corresponding Sun C compiler ended up with
+   "#define restrict _Restrict" or "#define restrict __restrict__"
+   in the previous line.  This workaround can be removed once
+   we assume Oracle Developer Studio 12.5 (2016) or later.  */
+#if defined __SUNPRO_CC && !defined __RESTRICT && !defined __restrict__
+# define _Restrict
+# define __restrict__
+#endif

configure.ac

@@ -0,0 +1,749 @@
+# configure.ac
+
+# Copyright (c) 2018-2024 Cosmin Truta
+# Copyright (c) 2004-2016 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
+
+dnl Process this file with autoconf to produce a configure script.
+dnl
+dnl Minor upgrades (compatible ABI): increment the package version
+dnl (third field in two places below) and set the PNGLIB_RELEASE
+dnl variable.
+dnl
+dnl Major upgrades (incompatible ABI): increment the package major
+dnl version (second field, or first if desired), set the minor
+dnl to 0, set PNGLIB_MAJOR below *and* follow the instructions in
+dnl Makefile.am to upgrade the package name.
+
+dnl This is here to prevent earlier autoconf from being used, it
+dnl should not be necessary to regenerate configure if the time
+dnl stamps are correct
+AC_PREREQ([2.68])
+
+dnl Version number stuff here:
+
+AC_INIT([libpng],[1.6.50.git],[png-mng-implement@lists.sourceforge.net])
+AC_CONFIG_MACRO_DIR([scripts/autoconf])
+
+# libpng does not follow GNU file name conventions (hence 'foreign')
+# color-tests requires automake 1.11 or later
+# silent-rules requires automake 1.11 or later
+# dist-xz requires automake 1.11 or later
+# 1.12.2 fixes a security issue in 1.11.2 and 1.12.1
+# 1.13 is required for parallel tests
+AM_INIT_AUTOMAKE([1.13 foreign dist-xz color-tests silent-rules subdir-objects])
+# The following line causes --disable-maintainer-mode to be the default to
+# configure. This is necessary because libpng distributions cannot rely on the
+# time stamps of the autotools generated files being correct
+AM_MAINTAINER_MODE
+
+dnl configure.ac and Makefile.am expect automake 1.11.2 or a compatible later
+dnl version; aclocal.m4 will generate a failure if you use a prior version of
+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=1.6.50.git
+PNGLIB_MAJOR=1
+PNGLIB_MINOR=6
+PNGLIB_RELEASE=50
+
+dnl End of version number stuff
+
+AC_CONFIG_SRCDIR([pngget.c])
+AC_CONFIG_HEADERS([config.h])
+
+# Check the basic programs.
+AC_LANG([C])
+AC_PROG_CC
+AM_PROG_AS
+LT_PATH_LD
+AC_PROG_CPP
+AC_PROG_AWK
+AC_PROG_INSTALL
+AC_PROG_LN_S
+AC_PROG_MAKE_SET
+
+dnl libtool/libtoolize; version 2.4.2 is the tested version. This or any
+dnl compatible later version may be used
+LT_INIT([win32-dll])
+LT_PREREQ([2.4.2])
+
+dnl Declare the AWK variable.
+AC_ARG_VAR(AWK, [AWK language processor])
+
+# Some awk implementations crash when confronted with pnglibconf.dfa.
+# Run a test now, to make sure this doesn't happen.
+AC_MSG_CHECKING([if awk ($AWK) works])
+if ${AWK} -f ${srcdir}/scripts/options.awk out="/dev/null" version=search\
+   ${srcdir}/pngconf.h ${srcdir}/scripts/pnglibconf.dfa\
+   ${srcdir}/pngusr.dfa 1>&2
+then
+   AC_MSG_RESULT([yes])
+else
+   AC_MSG_FAILURE([no], 1)
+fi
+
+# This is a remnant of the old cc -E validation, where it may have been
+# necessary to use a different preprocessor for .dfn files
+DFNCPP="$CPP"
+AC_SUBST(DFNCPP)
+
+AC_ARG_ENABLE([tests],
+   AS_HELP_STRING([--disable-tests],
+      [do not build the test programs (default is to build)]),
+      [enable_tests="$enableval"],
+      [enable_tests=yes])
+
+AM_CONDITIONAL([ENABLE_TESTS],
+   [test "$enable_tests" != "no"])
+
+AC_ARG_ENABLE([tools],
+   AS_HELP_STRING([--disable-tools],
+      [do not build the auxiliary tools (default is to build)]),
+      [enable_tools="$enableval"],
+      [enable_tools=yes])
+
+AM_CONDITIONAL([ENABLE_TOOLS],
+   [test "$enable_tools" != "no"])
+
+# -Werror cannot be passed to GCC in CFLAGS because configure will fail
+# (it checks the compiler with a program that generates a warning).
+# Add the following option to deal with this:
+AC_ARG_VAR(PNG_COPTS,
+   [additional flags for the C compiler, to be used for options that would]
+   [cause configure itself to fail])
+AC_ARG_ENABLE(werror,
+   AS_HELP_STRING([[[--enable-werror[=OPT]]]],
+      [Pass -Werror or the given argument to the compiler if it is supported]),
+   [test "$enable_werror" = "yes" && enable_werror="-Werror"
+    if test "$enable_werror" != "no"; then
+      sav_CFLAGS="$CFLAGS"
+      CFLAGS="$enable_werror $CFLAGS"
+      AC_MSG_CHECKING([if the compiler allows $enable_werror])
+      AC_COMPILE_IFELSE(
+         [AC_LANG_SOURCE([
+            [int main(int argc, char **argv){]
+            [return argv[argc-1][0];]
+            [}]])],
+         AC_MSG_RESULT(yes)
+         PNG_COPTS="$PNG_COPTS $enable_werror",
+         AC_MSG_RESULT(no))
+      CFLAGS="$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 structures and compiler characteristics.
+AC_STRUCT_TM
+AC_C_RESTRICT
+
+# Checks for library functions.
+AC_CHECK_FUNCS([pow], ,
+  [AC_CHECK_LIB([m], [pow], , [AC_MSG_ERROR([cannot find pow])])])
+
+# Some later POSIX 1003.1 functions are required for test programs, failure
+# here is soft (the corresponding test program is not built).
+AC_CHECK_FUNC([clock_gettime], , [AC_MSG_WARN([not building timepng])])
+AM_CONDITIONAL([HAVE_CLOCK_GETTIME], [test "$ac_cv_func_clock_gettime" = "yes"])
+
+AC_ARG_WITH(zlib-prefix,
+   AS_HELP_STRING([[[--with-zlib-prefix]]],
+      [prefix that may have been used in installed zlib]),
+      [ZPREFIX=${withval}],
+      [ZPREFIX='z_'])
+AC_CHECK_LIB([z], [zlibVersion], ,
+  [AC_CHECK_LIB([z], [${ZPREFIX}zlibVersion], ,
+     [AC_MSG_ERROR([zlib not installed])])])
+
+# The following is for pngvalid, to ensure it catches FP errors even on
+# platforms that don't enable FP exceptions, the function appears in the math
+# library (typically), it's not an error if it is not found.
+AC_CHECK_LIB([m], [feenableexcept])
+AC_CHECK_FUNCS([feenableexcept])
+
+AC_MSG_CHECKING([if using Solaris linker])
+SLD=`$LD --version 2>&1 | grep Solaris`
+if test "$SLD"; then
+    have_solaris_ld=yes
+    AC_MSG_RESULT(yes)
+else
+    have_solaris_ld=no
+    AC_MSG_RESULT(no)
+fi
+AM_CONDITIONAL(HAVE_SOLARIS_LD, test "$have_solaris_ld" = "yes")
+
+AC_MSG_CHECKING([if libraries can be versioned])
+# Special case for PE/COFF platforms: ld reports
+# support for version-script, but doesn't actually
+# DO anything with it.
+case $host in
+*cygwin* | *mingw32* | *interix* )
+    have_ld_version_script=no
+    AC_MSG_RESULT(no)
+;;
+* )
+
+if test "$have_solaris_ld" = "yes"; then
+    GLD=`$LD --help < /dev/null 2>&1 | grep 'M mapfile'`
+else
+    GLD=`$LD --help < /dev/null 2>/dev/null | grep version-script`
+fi
+
+if test "$GLD"; then
+    have_ld_version_script=yes
+    AC_MSG_RESULT(yes)
+else
+    have_ld_version_script=no
+    AC_MSG_RESULT(no)
+    AC_MSG_WARN(*** You have not enabled versioned symbols.)
+fi
+;;
+esac
+
+AM_CONDITIONAL(HAVE_LD_VERSION_SCRIPT, test "$have_ld_version_script" = "yes")
+
+if test "$have_ld_version_script" = "yes"; then
+    AC_MSG_CHECKING([for symbol prefix])
+    SYMBOL_PREFIX=`echo "PREFIX=__USER_LABEL_PREFIX__" \
+                  | ${CPP:-${CC:-gcc} -E} - 2>&1 \
+                  | ${EGREP:-grep} "^PREFIX=" \
+                  | ${SED:-sed} -e "s:^PREFIX=::" -e "s:__USER_LABEL_PREFIX__::"`
+    AC_SUBST(SYMBOL_PREFIX)
+    AC_MSG_RESULT($SYMBOL_PREFIX)
+fi
+
+# Substitutions for .in files
+AC_SUBST(PNGLIB_VERSION)
+AC_SUBST(PNGLIB_MAJOR)
+AC_SUBST(PNGLIB_MINOR)
+AC_SUBST(PNGLIB_RELEASE)
+
+# Additional arguments (and substitutions)
+# Allow the pkg-config directory to be set
+AC_ARG_WITH(pkgconfigdir,
+   AS_HELP_STRING([[[--with-pkgconfigdir]]],
+      [Use the specified pkgconfig dir (default is libdir/pkgconfig)]),
+   [pkgconfigdir=${withval}],
+   [pkgconfigdir='${libdir}/pkgconfig'])
+
+AC_SUBST([pkgconfigdir])
+AC_MSG_NOTICE([[pkgconfig directory is ${pkgconfigdir}]])
+
+# Make the *-config binary config scripts optional
+AC_ARG_WITH(binconfigs,
+   AS_HELP_STRING([[[--with-binconfigs]]],
+      [Generate shell libpng-config scripts as well as pkg-config data]
+      [@<:@default=yes@:>@]),
+   [if test "${withval}" = no; then
+      binconfigs=
+      AC_MSG_NOTICE([[libpng-config scripts will not be built]])
+    else
+      binconfigs='${binconfigs}'
+    fi],
+   [binconfigs='${binconfigs}'])
+AC_SUBST([binconfigs])
+
+# Support for prefixes to the API function names; this will generate defines
+# at the start of the build to rename exported library functions
+AC_ARG_WITH(libpng-prefix,
+   AS_HELP_STRING([[[--with-libpng-prefix]]],
+      [prefix libpng exported function (API) names with the given value]),
+   [if test "${withval:-no}" != "no"; then
+      AC_SUBST([PNG_PREFIX], [${withval}])
+    fi])
+AM_CONDITIONAL([DO_PNG_PREFIX], [test "${with_libpng_prefix:-no}" != "no"])
+
+# Control over what links are made for installed files.  Versioned files are
+# always installed, when the following options are turned on corresponding
+# unversioned links are also created (normally as symbolic links):
+AC_ARG_ENABLE([unversioned-links],
+   AS_HELP_STRING([[[--enable-unversioned-links]]],
+      [Installed libpng header files are placed in a versioned subdirectory]
+      [and installed libpng library (including DLL) files are versioned.]
+      [If this option is enabled unversioned links will be created pointing to]
+      [the corresponding installed files.  If you use libpng.pc or]
+      [libpng-config for all builds you do not need these links, but if you]
+      [compile programs directly they will typically #include <png.h> and]
+      [link with -lpng; in that case you need the links.]
+      [The links can be installed manually using 'make install-header-links']
+      [and 'make install-library-links' and can be removed using the]
+      [corresponding uninstall- targets.  If you do enable this option every]
+      [libpng 'make install' will recreate the links to point to the just]
+      [installed version of libpng.  The default is to create the links;]
+      [use --disable-unversioned-links to change this]))
+
+# The AM_CONDITIONAL test is written so that the default is enabled;
+# --disable-unversioned-links must be given to turn the option off.
+AM_CONDITIONAL([DO_INSTALL_LINKS],[test "$enable_unversioned_links" != "no"])
+
+AC_ARG_ENABLE([unversioned-libpng-pc],
+   AS_HELP_STRING([[[--enable-unversioned-libpng-pc]]],
+      [Install the configuration file 'libpng.pc' as a link to the versioned]
+      [version.  This is done by default - use --disable-unversioned-libpng-pc]
+      [to change this.]))
+AM_CONDITIONAL([DO_INSTALL_LIBPNG_PC],
+   [test "$enable_unversioned_libpng_pc" != "no"])
+
+AC_ARG_ENABLE([unversioned-libpng-config],
+   AS_HELP_STRING([[[--enable-unversioned-libpng-config]]],
+      [Install the configuration file 'libpng-config' as a link to the]
+      [versioned version.  This is done by default - use]
+      [--disable-unversioned-libpng-config to change this.]))
+AM_CONDITIONAL([DO_INSTALL_LIBPNG_CONFIG],
+   [test "$enable_unversioned_libpng_config" != "no"])
+
+# HOST-SPECIFIC OPTIONS
+# =====================
+#
+# DEFAULT
+# =======
+#
+AC_ARG_ENABLE([hardware-optimizations],
+   AS_HELP_STRING([[[--enable-hardware-optimizations]]],
+      [Enable hardware optimizations: =no/off, yes/on.]),
+   [case "$enableval" in
+      no|off)
+         # disable hardware optimization on all systems:
+         enable_arm_neon=no
+         AC_DEFINE([PNG_ARM_NEON_OPT], [0],
+           [Disable ARM_NEON optimizations])
+         enable_mips_msa=no
+         AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
+           [Disable MIPS_MSA optimizations])
+         enable_mips_mmi=no
+         AC_DEFINE([PNG_MIPS_MMI_OPT], [0],
+           [Disable MIPS_MMI optimizations])
+         enable_powerpc_vsx=no
+         AC_DEFINE([PNG_POWERPC_VSX_OPT], [0],
+           [Disable POWERPC VSX optimizations])
+         enable_intel_sse=no
+         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
+           [Disable INTEL_SSE optimizations])
+         enable_loongarch_lsx=no
+         AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [0],
+           [Disable LOONGARCH_LSX optimizations])
+         enable_riscv_rvv=no
+         AC_DEFINE([PNG_RISCV_RVV_OPT], [0],
+           [Disable RISC-V Vector optimizations])
+         ;;
+      *)
+         # allow enabling hardware optimization on any system:
+         case "$host_cpu" in
+            arm*|aarch64*)
+              enable_arm_neon=yes
+              AC_DEFINE([PNG_ARM_NEON_OPT], [2],
+                [Enable ARM_NEON optimizations])
+              ;;
+            mipsel*|mips64el*)
+              enable_mips_mmi=yes
+              enable_mips_msa=yes
+              AC_DEFINE([PNG_MIPS_MMI_OPT], [1],
+                [Enable MIPS_MMI optimizations])
+              AC_DEFINE([PNG_MIPS_MSA_OPT], [2],
+                [Enable MIPS_MSA optimizations])
+              ;;
+            i?86|x86_64)
+              enable_intel_sse=yes
+              AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
+                [Enable Intel SSE optimizations])
+              ;;
+            powerpc*|ppc64*)
+              enable_powerpc_vsx=yes
+              AC_DEFINE([PNG_POWERPC_VSX_OPT], [2],
+                [Enable POWERPC VSX optimizations])
+              ;;
+            loongarch*)
+              enable_loongarch_lsx=yes
+              AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [1],
+                [Enable LOONGARCH_LSX optimizations])
+              ;;
+            riscv64)
+              enable_riscv_rvv=yes
+              AC_DEFINE([PNG_RISCV_RVV_OPT], [2],
+                [Enable RISC-V Vector optimizations])
+              ;;
+         esac
+         ;;
+   esac])
+
+# ARM NEON
+# ========
+
+AC_ARG_ENABLE([arm-neon],
+   AS_HELP_STRING([[[--enable-arm-neon]]],
+      [Enable ARM NEON optimizations: =no/off, check, api, yes/on.]
+      [no/off: disable the optimizations;]
+      [check: use internal checking code (deprecated and poorly supported);]
+      [api: disable by default, enable by a call to png_set_option;]
+      [yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __ARM_NEON__ systems:
+         AC_DEFINE([PNG_ARM_NEON_OPT], [0],
+                   [Disable ARM Neon optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_arm_neon=no ;;
+      check)
+         AC_DEFINE([PNG_ARM_NEON_CHECK_SUPPORTED], [],
+                   [Check for ARM Neon support at run-time]);;
+      api)
+         AC_DEFINE([PNG_ARM_NEON_API_SUPPORTED], [],
+                   [Turn on ARM Neon optimizations at run-time]);;
+      yes|on)
+         AC_DEFINE([PNG_ARM_NEON_OPT], [2],
+                   [Enable ARM Neon optimizations])
+         AC_MSG_WARN([--enable-arm-neon: please specify 'check' or 'api';]
+            [if you want the optimizations unconditionally,]
+            [pass '-mfpu=neon' to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-arm-neon=${enable_arm_neon}:]
+                      [invalid argument])
+   esac])
+
+# Add ARM-specific files to all builds where $host_cpu is arm ('arm*') or
+# where ARM optimizations were explicitly requested. (This allows a fallback
+# if a future host CPU does not match 'arm*'.)
+
+AM_CONDITIONAL([PNG_ARM_NEON],
+   [test "$enable_arm_neon" != 'no' &&
+    case "$host_cpu" in
+      arm*|aarch64*) : ;;
+      *)    test "$enable_arm_neon" != '' ;;
+    esac])
+
+# MIPS MSA
+# ========
+
+AC_ARG_ENABLE([mips-msa],
+   AS_HELP_STRING([[[--enable-mips-msa]]],
+      [Enable MIPS MSA optimizations: =no/off, check, api, yes/on.]
+      [no/off: disable the optimizations;]
+      [check: use internal checking code (deprecated and poorly supported);]
+      [api: disable by default, enable by a call to png_set_option;]
+      [yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __mips_msa systems:
+         AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
+                   [Disable MIPS MSA optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_mips_msa=no ;;
+      check)
+         AC_DEFINE([PNG_MIPS_MSA_CHECK_SUPPORTED], [],
+                   [Check for MIPS MSA support at run-time]);;
+      api)
+         AC_DEFINE([PNG_MIPS_MSA_API_SUPPORTED], [],
+                   [Turn on MIPS MSA optimizations at run-time]);;
+      yes|on)
+         AC_DEFINE([PNG_MIPS_MSA_OPT], [2],
+                   [Enable MIPS MSA optimizations])
+         AC_MSG_WARN([--enable-mips-msa: please specify 'check' or 'api';]
+            [if you want the optimizations unconditionally,]
+            [pass '-mmsa -mfp64' to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-mips-msa=${enable_mips_msa}:]
+                      [invalid argument])
+   esac])
+
+# Add MIPS-specific files to all builds where $host_cpu is mips ('mips*') or
+# where MIPS optimizations were explicitly requested. (This allows a fallback
+# if a future host CPU does not match 'mips*'.)
+
+AM_CONDITIONAL([PNG_MIPS_MSA],
+   [test "$enable_mips_msa" != 'no' &&
+    case "$host_cpu" in
+      mipsel*|mips64el*) : ;;
+    esac])
+
+# MIPS MMI
+# ========
+
+AC_ARG_ENABLE([mips-mmi],
+   AS_HELP_STRING([[[--enable-mips-mmi]]],
+      [Enable MIPS MMI optimizations: =no/off, check, api, yes/on.]
+      [no/off: disable the optimizations;]
+      [check: use internal checking code (deprecated and poorly supported);]
+      [api: disable by default, enable by a call to png_set_option;]
+      [yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __mips_mmi systems:
+         AC_DEFINE([PNG_MIPS_MMI_OPT], [0],
+                   [Disable MIPS MMI optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_mips_mmi=no;;
+      check)
+         AC_DEFINE([PNG_MIPS_MMI_CHECK_SUPPORTED], [],
+                   [Check for MIPS MMI support at run-time]);;
+      api)
+         AC_DEFINE([PNG_MIPS_MMI_API_SUPPORTED], [],
+                   [Turn on MIPS MMI optimizations at run-time]);;
+      yes|on)
+         AC_DEFINE([PNG_MIPS_MMI_OPT], [1],
+                   [Enable MIPS MMI optimizations])
+         AC_MSG_WARN([--enable-mips-mmi: please specify 'check' or 'api';]
+            [if you want the optimizations unconditionally]
+            [pass '-mloongson-mmi -march=loongson3a' to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-mips-mmi=${enable_mips_mmi}:]
+                      [invalid argument])
+   esac])
+
+# Add MIPS specific files to all builds where the host_cpu is mips ('mips*') or
+# where MIPS optimizations were explicitly requested. (This allows a fallback
+# if a future host CPU does not match 'mips*'.)
+
+AM_CONDITIONAL([PNG_MIPS_MMI],
+   [test "$enable_mips_mmi" != 'no' &&
+    case "$host_cpu" in
+      mipsel*|mips64el*) : ;;
+    esac])
+
+# INTEL SSE
+# =========
+
+AC_ARG_ENABLE([intel-sse],
+   AS_HELP_STRING([[[--enable-intel-sse]]],
+      [Enable Intel SSE optimizations: =no/off, yes/on.]
+      [no/off: disable the optimizations;]
+      [yes/on: enable the optimizations.]
+      [If not specified: determined by the compiler.]),
+   [case "$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 argument])
+   esac])
+
+# Add Intel-specific files to all builds where $host_cpu is Intel ('x86*') or
+# where Intel optimizations were explicitly requested. (This allows a fallback
+# if a future host CPU does not match 'x86*'.)
+AM_CONDITIONAL([PNG_INTEL_SSE],
+   [test "$enable_intel_sse" != 'no' &&
+    case "$host_cpu" in
+      i?86|x86_64) : ;;
+      *)    test "$enable_intel_sse" != '' ;;
+    esac])
+
+# POWERPC VSX
+# ===========
+
+AC_ARG_ENABLE([powerpc-vsx],
+AS_HELP_STRING([[[--enable-powerpc-vsx]]],
+      [Enable POWERPC VSX optimizations: =no/off, check, api, yes/on.]
+      [no/off: disable the optimizations;]
+      [check: use internal checking code;]
+      [api: disable by default, enable by a call to png_set_option;]
+      [yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __ppc64__ systems:
+         AC_DEFINE([PNG_POWERPC_VSX_OPT], [0],
+                   [Disable POWERPC VSX optimizations])
+         # Prevent inclusion of the platform-specific files below:
+         enable_powerpc_vsx=no ;;
+      check)
+         AC_DEFINE([PNG_POWERPC_VSX_CHECK_SUPPORTED], [],
+                   [Check for POWERPC VSX support at run-time])
+         AC_MSG_WARN([--enable-powerpc-vsx: please see contrib/powerpc/README]
+                     [for the list of supported systems.]);;
+      api)
+         AC_DEFINE([PNG_POWERPC_VSX_API_SUPPORTED], [],
+                   [Turn on POWERPC VSX optimizations at run-time]);;
+      yes|on)
+         AC_DEFINE([PNG_POWERPC_VSX_OPT], [2],
+                   [Enable POWERPC VSX optimizations])
+         AC_MSG_WARN([--enable-powerpc-vsx: please specify 'check' or 'api';]
+            [if you want the optimizations unconditionally,]
+            [pass '-maltivec -mvsx' or '-mcpu=power8' to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-powerpc-vsx=${enable_powerpc_vsx}:]
+                      [invalid argument])
+   esac])
+
+# Add PowerPC-specific files to all builds where $host_cpu is powerpc
+# ('powerpc*') or where PowerPC optimizations were explicitly requested.
+# (This allows a fallback if a future host CPU does not match 'powerpc*'.)
+
+AM_CONDITIONAL([PNG_POWERPC_VSX],
+   [test "$enable_powerpc_vsx" != 'no' &&
+    case "$host_cpu" in
+      powerpc*|ppc64*) : ;;
+    esac])
+
+# LOONGARCH LSX
+# =============
+
+AC_ARG_ENABLE([loongarch-lsx],
+   AS_HELP_STRING([[[--enable-loongarch-lsx]]],
+      [Enable LOONGARCH LSX optimizations: =no/off, yes/on:]
+      [no/off: disable the optimizations;]
+      [yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __loongarch_simd systems:
+         AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [0],
+                   [Disable LOONGARCH LSX optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_loongarch_lsx=no;;
+      yes|on)
+         AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [1],
+                   [Enable LOONGARCH LSX optimizations])
+         ;;
+      *)
+         AC_MSG_ERROR([--enable-loongarch-lsx=${enable_loongarch_lsx}:]
+                      [invalid argument])
+   esac])
+
+if test "$enable_loongarch_lsx" != "no" &&
+   case "$host_cpu" in
+      loongarch*) : ;;
+      *)    test "$enable_loongarch_lsx" != '' ;;
+   esac
+then
+   compiler_support_loongarch_lsx=no
+   AC_MSG_CHECKING(whether to use LoongArch LSX intrinsics)
+   save_CFLAGS="$CFLAGS"
+   LSX_CFLAGS="${LSX_CFLAGS:-"-mlsx"}"
+   CFLAGS="$CFLAGS $LSX_CFLAGS"
+   AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <lsxintrin.h>
+int main(){
+   __m128i a, b, c;
+   a = __lsx_vadd_w(b, c);
+   return 0;
+}]])],compiler_support_loongarch_lsx=yes)
+   CFLAGS="$save_CFLAGS"
+   AC_MSG_RESULT($compiler_support_loongarch_lsx)
+   if test "$compiler_support_loongarch_lsx" = "yes"; then
+      AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [1],
+                [Enable LOONGARCH LSX optimizations])
+   else
+      AC_MSG_WARN([Compiler does not support loongarch LSX.])
+   fi
+fi
+
+# Add LoongArch specific files to all builds where the host_cpu is loongarch
+# ('loongarch*') or where LoongArch optimizations were explicitly requested.
+# (This allows a fallback if a future host CPU does not match 'loongarch*'.)
+
+AM_CONDITIONAL([PNG_LOONGARCH_LSX],
+   [test "$enable_loongarch_lsx" != "no" &&
+    test "$compiler_support_loongarch_lsx" = "yes" &&
+    case "$host_cpu" in
+      loongarch*) : ;;
+      *)    test "$enable_loongarch_lsx" != '' ;;
+    esac])
+
+# RISC-V
+# ======
+#
+# RISC-V Vector support.
+
+AC_ARG_ENABLE([riscv-rvv],
+AS_HELP_STRING([[[--enable-riscv-rvv]]],
+      [Enable RISC-V Vector optimizations: =no/off, check, api, yes/on:]
+      [no/off: disable the optimizations; check: use internal checking code]
+      [api: disable by default, enable by a call to png_set_option]
+      [yes/on: turn on. If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __riscv systems:
+         AC_DEFINE([PNG_RISCV_RVV_OPT], [0],
+                   [Disable RISC-V Vector optimizations])
+         # Prevent inclusion of the platform-specific files below:
+         enable_riscv_rvv=no ;;
+      yes|on)
+         AC_DEFINE([PNG_RISCV_RVV_OPT], [2],
+                   [Enable RISC-V Vector optimizations])
+         AC_MSG_WARN([--enable-riscv-rvv:]
+            [if you want the optimizations pass e.g. '-march=rv64gv1p0' to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-riscv-rvv=${enable_riscv_rvv}: invalid value])
+   esac])
+
+if test "$enable_riscv_rvv" != "no" &&
+   case "$host_cpu" in
+      riscv64) : ;;
+      *)    test "$enable_riscv_rvv" != '' ;;
+   esac
+then
+   compiler_support_riscv_rvv=no
+   AC_MSG_CHECKING(whether to use RISC-V RVV intrinsics)
+
+   AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <riscv_vector.h>
+#include <asm/hwcap.h>
+#ifndef COMPAT_HWCAP_ISA_V /* added in linux-6.5 */
+#error "COMPAT_HWCAP_ISA_V is not available"
+#endif
+int main() {
+   const float src[] = { 0.0f, 0.0f, 0.0f, 0.0f };
+   uint64_t ptr[2] = {0x0908060504020100, 0xFFFFFFFF0E0D0C0A};
+   vuint8m1_t a = __riscv_vreinterpret_v_u64m1_u8m1(__riscv_vle64_v_u64m1(ptr, 2));
+   vfloat32m1_t val = __riscv_vle32_v_f32m1((const float*)(src), 4);
+   return (int)__riscv_vfmv_f_s_f32m1_f32(val);
+}]])],compiler_support_riscv_rvv=yes)
+   AC_MSG_RESULT($compiler_support_riscv_rvv)
+   if test "$compiler_support_riscv_rvv" = "yes"; then
+      AC_DEFINE([PNG_RISCV_RVV_OPT], [1],
+                [Enable RISCV RVV optimizations])
+   else
+      AC_MSG_WARN([Compiler does not support riscv rvv.])
+   fi
+fi
+
+# Add RISC-V-specific files to all builds where $host_cpu is riscv ('riscv64')
+# or where RISC-V optimizations were explicitly requested (this allows a fallback
+# if a future host CPU does not match 'riscv64')
+
+AM_CONDITIONAL([PNG_RISCV_RVV],
+   [test "$enable_riscv_rvv" != "no" &&
+    test "$compiler_support_riscv_rvv" = "yes" &&
+    case "$host_cpu" in
+      riscv64) : ;;
+      *)    test "$compiler_support_riscv_rvv" != '' ;;
+    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

contrib/.editorconfig

@@ -0,0 +1,9 @@
+# https://editorconfig.org
+
+root = false
+
+[*.[ch]]
+indent_size = unset
+indent_style = unset
+max_doc_length = unset
+max_line_length = unset

contrib/README.txt

@@ -0,0 +1,7 @@
+External contributions to libpng
+--------------------------------
+
+This "contrib" directory contains contributions which are not necessarily under
+the libpng license, although all are open source.  They are not part of
+libpng proper and are not used for building the library, although some are used
+for testing the library via "make check".

contrib/arm-neon/README

@@ -0,0 +1,83 @@
+OPERATING SYSTEM SPECIFIC ARM NEON DETECTION
+--------------------------------------------
+
+Detection of the ability to execute ARM NEON on an ARM processor requires
+operating system support.  (The information is not available in user mode.)
+
+HOW TO USE THIS
+---------------
+
+This directory contains C code fragments that can be included in arm/arm_init.c
+by setting the macro PNG_ARM_NEON_FILE to the file name in "" or <> at build
+time.  This setting is not recorded in pnglibconf.h and can be changed simply by
+rebuilding arm/arm_init.o with the required macro definition.
+
+For any of this code to be used the ARM NEON code must be enabled and run time
+checks must be supported.  I.e.:
+
+#if PNG_ARM_NEON_OPT > 0
+#ifdef PNG_ARM_NEON_CHECK_SUPPORTED
+
+This is done in a 'configure' build by passing configure the argument:
+
+   --enable-arm-neon=check
+
+Apart from the basic Linux implementation in contrib/arm-neon/linux.c this code
+is unsupported.  That means that it is not even compiled on a regular basis and
+may be broken in any given minor release.
+
+FILE FORMAT
+-----------
+
+Each file documents its testing status as of the last time it was tested (which
+may have been a long time ago):
+
+STATUS: one of:
+   SUPPORTED: This indicates that the file is included in the regularly
+         performed test builds and bugs are fixed when discovered.
+   COMPILED: This indicates that the code did compile at least once.  See the
+         more detailed description for the extent to which the result was
+         successful.
+   TESTED: This means the code was fully compiled into the libpng test programs
+         and these were run at least once.
+
+BUG REPORTS: an email address to which to send reports of problems
+
+The file is a fragment of C code. It should not define any 'extern' symbols;
+everything should be static.  It must define the function:
+
+static int png_have_neon(png_structp png_ptr);
+
+That function must return 1 if ARM NEON instructions are supported, 0 if not.
+It must not execute png_error unless it detects a bug.  A png_error will prevent
+the reading of the PNG and in the future, writing too.
+
+BUG REPORTS
+-----------
+
+If you mail a bug report for any file that is not SUPPORTED there may only be
+limited response.  Consider fixing it and sending a patch to fix the problem -
+this is more likely to result in action.
+
+CONTRIBUTIONS
+-------------
+
+You may send contributions of new implementations to
+png-mng-implement@sourceforge.net.  Please write code in strict C90 C where
+possible.  Obviously OS dependencies are to be expected.  If you submit code you
+must have the authors permission and it must have a license that is acceptable
+to the current maintainer; in particular that license must permit modification
+and redistribution.
+
+Please try to make the contribution a single file and give the file a clear and
+unambiguous name that identifies the target OS.  If multiple files really are
+required put them all in a sub-directory.
+
+You must also be prepared to handle bug reports from users of the code, either
+by joining the png-mng-implement mailing list or by providing an email for the
+"BUG REPORTS" entry or both.  Please make sure that the header of the file
+contains the STATUS and BUG REPORTS fields as above.
+
+Please list the OS requirements as precisely as possible.  Ideally you should
+also list the environment in which the code has been tested and certainly list
+any environments where you suspect it might not work.

contrib/arm-neon/android-ndk.c

@@ -0,0 +1,39 @@
+/* contrib/arm-neon/android-ndk.c
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by John Bowler, 2014.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * SEE contrib/arm-neon/README before reporting bugs
+ *
+ * STATUS: COMPILED, UNTESTED
+ * BUG REPORTS: png-mng-implement@sourceforge.net
+ *
+ * png_have_neon implemented for the Android NDK, see:
+ *
+ * Documentation:
+ *    http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html
+ *    https://code.google.com/p/android/issues/detail?id=49065
+ *
+ * NOTE: this requires that libpng is built against the Android NDK and linked
+ * with an implementation of the Android ARM 'cpu-features' library.  The code
+ * has been compiled only, not linked: no version of the library has been found,
+ * only the header files exist in the NDK.
+ */
+
+#include <cpu-features.h>
+
+static int
+png_have_neon(png_structp png_ptr)
+{
+   /* This is a whole lot easier than the linux code, however it is probably
+    * implemented as below, therefore it is better to cache the result (these
+    * function calls may be slow!)
+    */
+   PNG_UNUSED(png_ptr)
+   return android_getCpuFamily() == ANDROID_CPU_FAMILY_ARM &&
+      (android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) != 0;
+}

contrib/arm-neon/linux-auxv.c

@@ -0,0 +1,120 @@
+/* contrib/arm-neon/linux-auxv.c
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by Mans Rullgard, 2011.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * SEE contrib/arm-neon/README before reporting bugs
+ *
+ * STATUS: COMPILED, TESTED
+ * BUG REPORTS: png-mng-implement@sourceforge.net
+ *
+ * png_have_neon implemented for Linux versions which allow access to
+ * /proc/self/auxv.  This is probably faster, cleaner and safer than the code to
+ * read /proc/cpuinfo in contrib/arm-neon/linux, however it is yet another piece
+ * of potentially untested code and has more complex dependencies than the code
+ * to read cpuinfo.
+ *
+ * This generic __linux__ implementation requires reading /proc/self/auxv and
+ * looking at each element for one that records NEON capabilities.
+ */
+
+#include <unistd.h> /* for POSIX 1003.1 */
+#include <errno.h>  /* for EINTR */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <elf.h>
+#include <asm/hwcap.h>
+
+/* A read call may be interrupted, in which case it returns -1 and sets errno to
+ * EINTR if nothing was done, otherwise (if something was done) a partial read
+ * may result.
+ */
+static size_t
+safe_read(png_structp png_ptr, int fd, void *buffer_in, size_t nbytes)
+{
+   size_t ntotal = 0;
+   char *buffer = png_voidcast(char*, buffer_in);
+
+   while (nbytes > 0)
+   {
+      unsigned int nread;
+      int iread;
+
+      /* Passing nread > INT_MAX to read is implementation defined in POSIX
+       * 1003.1, therefore despite the unsigned argument portable code must
+       * limit the value to INT_MAX!
+       */
+      if (nbytes > INT_MAX)
+         nread = INT_MAX;
+
+      else
+         nread = (unsigned int)/*SAFE*/nbytes;
+
+      iread = read(fd, buffer, nread);
+
+      if (iread == -1)
+      {
+         /* This is the devil in the details, a read can terminate early with 0
+          * bytes read because of EINTR, yet it still returns -1 otherwise end
+          * of file cannot be distinguished.
+          */
+         if (errno != EINTR)
+         {
+            png_warning(png_ptr, "/proc read failed");
+            return 0; /* I.e., a permanent failure */
+         }
+      }
+
+      else if (iread < 0)
+      {
+         /* Not a valid 'read' result: */
+         png_warning(png_ptr, "OS /proc read bug");
+         return 0;
+      }
+
+      else if (iread > 0)
+      {
+         /* Continue reading until a permanent failure, or EOF */
+         buffer += iread;
+         nbytes -= (unsigned int)/*SAFE*/iread;
+         ntotal += (unsigned int)/*SAFE*/iread;
+      }
+
+      else
+         return ntotal;
+   }
+
+   return ntotal; /* nbytes == 0 */
+}
+
+static int
+png_have_neon(png_structp png_ptr)
+{
+   int fd = open("/proc/self/auxv", O_RDONLY);
+   Elf32_auxv_t aux;
+
+   /* Failsafe: failure to open means no NEON */
+   if (fd == -1)
+   {
+      png_warning(png_ptr, "/proc/self/auxv open failed");
+      return 0;
+   }
+
+   while (safe_read(png_ptr, fd, &aux, sizeof aux) == sizeof aux)
+   {
+      if (aux.a_type == AT_HWCAP && (aux.a_un.a_val & HWCAP_NEON) != 0)
+      {
+         close(fd);
+         return 1;
+      }
+   }
+
+   close(fd);
+   return 0;
+}

contrib/arm-neon/linux.c

@@ -0,0 +1,161 @@
+/* contrib/arm-neon/linux.c
+ *
+ * Copyright (c) 2014, 2017 Glenn Randers-Pehrson
+ * Written by John Bowler, 2014, 2017.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * SEE contrib/arm-neon/README before reporting bugs
+ *
+ * STATUS: SUPPORTED
+ * BUG REPORTS: png-mng-implement@sourceforge.net
+ *
+ * png_have_neon implemented for Linux by reading the widely available
+ * pseudo-file /proc/cpuinfo.
+ *
+ * This code is strict ANSI-C and is probably moderately portable; it does
+ * however use <stdio.h> and it assumes that /proc/cpuinfo is never localized.
+ */
+
+#include <stdio.h>
+
+static int
+png_have_neon(png_structp png_ptr)
+{
+   FILE *f = fopen("/proc/cpuinfo", "rb");
+
+   if (f != NULL)
+   {
+      /* This is a simple state machine which reads the input byte-by-byte until
+       * it gets a match on the 'neon' feature or reaches the end of the stream.
+       */
+      static const char ch_feature[] = { 70, 69, 65, 84, 85, 82, 69, 83 };
+      static const char ch_neon[] = { 78, 69, 79, 78 };
+
+      enum
+      {
+         StartLine, Feature, Colon, StartTag, Neon, HaveNeon, SkipTag, SkipLine
+      }  state;
+      int counter;
+
+      for (state=StartLine, counter=0;;)
+      {
+         int ch = fgetc(f);
+
+         if (ch == EOF)
+         {
+            /* EOF means error or end-of-file, return false; neon at EOF is
+             * assumed to be a mistake.
+             */
+            fclose(f);
+            return 0;
+         }
+
+         switch (state)
+         {
+            case StartLine:
+               /* Match spaces at the start of line */
+               if (ch <= 32) /* skip control characters and space */
+                  break;
+
+               counter=0;
+               state = Feature;
+               /* FALLTHROUGH */
+
+            case Feature:
+               /* Match 'FEATURE', ASCII case insensitive. */
+               if ((ch & ~0x20) == ch_feature[counter])
+               {
+                  if (++counter == (sizeof ch_feature))
+                     state = Colon;
+                  break;
+               }
+
+               /* did not match 'feature' */
+               state = SkipLine;
+               /* FALLTHROUGH */
+
+            case SkipLine:
+            skipLine:
+               /* Skip everything until we see linefeed or carriage return */
+               if (ch != 10 && ch != 13)
+                  break;
+
+               state = StartLine;
+               break;
+
+            case Colon:
+               /* Match any number of space or tab followed by ':' */
+               if (ch == 32 || ch == 9)
+                  break;
+
+               if (ch == 58) /* i.e. ':' */
+               {
+                  state = StartTag;
+                  break;
+               }
+
+               /* Either a bad line format or a 'feature' prefix followed by
+                * other characters.
+                */
+               state = SkipLine;
+               goto skipLine;
+
+            case StartTag:
+               /* Skip space characters before a tag */
+               if (ch == 32 || ch == 9)
+                  break;
+
+               state = Neon;
+               counter = 0;
+               /* FALLTHROUGH */
+
+            case Neon:
+               /* Look for 'neon' tag */
+               if ((ch & ~0x20) == ch_neon[counter])
+               {
+                  if (++counter == (sizeof ch_neon))
+                     state = HaveNeon;
+                  break;
+               }
+
+               state = SkipTag;
+               /* FALLTHROUGH */
+
+            case SkipTag:
+               /* Skip non-space characters */
+               if (ch == 10 || ch == 13)
+                  state = StartLine;
+
+               else if (ch == 32 || ch == 9)
+                  state = StartTag;
+               break;
+
+            case HaveNeon:
+               /* Have seen a 'neon' prefix, but there must be a space or new
+                * line character to terminate it.
+                */
+               if (ch == 10 || ch == 13 || ch == 32 || ch == 9)
+               {
+                  fclose(f);
+                  return 1;
+               }
+
+               state = SkipTag;
+               break;
+
+            default:
+               png_error(png_ptr, "png_have_neon: internal error (bug)");
+         }
+      }
+   }
+
+#ifdef PNG_WARNINGS_SUPPORTED
+   else
+      png_warning(png_ptr, "/proc/cpuinfo open failed");
+#endif
+
+   return 0;
+}

contrib/conftest/README

@@ -0,0 +1,49 @@
+This directory contains test configuration files, currently always '.dfa' files
+intended to be used in the build by setting the make macro DFA_XTRA to the name
+of the file.
+
+These files are used in release validation of the 'configure' builds of libpng
+by building 'make check', or 'make all-am' for cross-builds, with each .dfa
+file.
+
+The files in this directory may change between minor releases, however
+contributions describing specific builds of libpng are welcomed.  There is no
+guarantee that libpng will continue to build with such configurations; support
+for given configurations can be, and has been, dropped between successive minor
+releases.  However if a .dfa file describing a configuration is not in this
+directory it is very unlikely that it will be tested before a minor release!
+
+You can use these .dfa files as the basis of new configurations.  Files in this
+directory should not have any use restrictions or restrictive licenses.
+
+This directory is not included in the .zip and .7z distributions, which do
+not contain 'configure' scripts.
+
+DOCUMENTATION
+=============
+
+Examples:
+   ${srcdir}/pngusr.dfa
+   ${srcdir}/contrib/pngminim/*/pngusr.dfa
+
+Documentation of the options:
+   ${srcdir}/scripts/pnglibconf.dfa
+
+Documentation of the file format:
+   ${srcdir}/scripts/options.awk
+
+FILE NAMING
+===========
+
+File names in this directory may NOT contain any of the five characters:
+
+   - , + * ?
+
+Neither may they contain any space character.
+
+While other characters may be used it is strongly suggested that file names be
+limited to lower case Latiin alphabetic characters (a-z), digits (0-9) and, if
+necessary the underscore (_) character.  File names should be about 8 characters
+long (excluding the .dfa extension).  Submitted .dfa files should have names
+between 7 and 16 characters long, shorter names (6 characters or less) are
+reserved for standard tests.

contrib/conftest/basic.dfa

@@ -0,0 +1,133 @@
+# basic.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2024
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with basic read and write support.  This enables the lowest
+# level libpng read and write APIs - the "row-by-row" ones.
+#
+# Support is enabled only for those transformations that are observed to be
+# required by widely used apps or are in the v3 specification.
+#
+
+everything = off
+
+# The sequential read code is enabled here; the progressive code can be used
+# instead but there is no point enabling both.
+
+option READ on
+option SEQUENTIAL_READ on
+option EASY_ACCESS on
+option SET_USER_LIMITS on
+option INFO_IMAGE on
+option READ_16BIT on
+
+# Errors: these can be disabled but then there won't be any error messages
+# just failures and the error messages are really needed for apps:
+option WARNINGS on
+option ERROR_TEXT on
+option BENIGN_READ_ERRORS on
+
+# Required for many display programs such as web browsers:
+option PROGRESSIVE_READ on
+
+# Switch on the write code - this makes a minimalist encoder but with
+# interlace support turned on; otherwise png_read_png..png_write_png will
+# fail on an interlaced image.
+option WRITE on
+option WRITE_INTERLACING on
+option WRITE_16BIT on
+
+# Usages of the 'fixed' APIs are relatively rare but they do occur
+# one or the other for both the API and the internal math.
+
+#Fixed point:
+option FIXED_POINT on
+
+#Floating point:
+option FLOATING_POINT on
+option FLOATING_ARITHMETIC on
+
+# Basic error handling, IO and user memory support.  The latter allows the
+# application program to provide its own implementations of 'malloc' and 'free'.
+option SETJMP on
+option STDIO on
+option USER_MEM on
+
+# Gamma handling: this needs to be on for the gamma handling
+option READ_GAMMA on
+
+# The supported chunks
+chunk bKGD on
+chunk cHRM on
+chunk eXIf on
+chunk gAMA on
+chunk iCCP on
+chunk iTXt on
+chunk pHYs on
+chunk sBIT on
+chunk sRGB on
+chunk tEXt on
+chunk tIME on
+chunk tRNS on
+chunk zTXt on
+
+# These don't seem to be used anywhere:
+# chunk pCAL
+# chunk sCAL
+# chunk sPLT
+
+# The rest of this is app dependent: none of these options are required for
+# read/write of the full range of PNG files and the normal chunk handling on
+# read.
+option WRITE_CUSTOMIZE_ZTXT_COMPRESSION on
+option WRITE_CUSTOMIZE_COMPRESSION on
+
+option READ_EXPAND on
+option READ_FILLER on
+option READ_GRAY_TO_RGB on
+option READ_INVERT on
+option READ_PACK on
+option READ_RGB_TO_GRAY on
+option READ_SCALE_16_TO_8 on
+option READ_SHIFT on
+option READ_STRIP_16_TO_8 on
+option READ_STRIP_ALPHA on
+option READ_SWAP on
+
+option CONVERT_tIME on
+
+# optipng
+option IO_STATE on
+option STORE_UNKNOWN_CHUNKS on
+option HANDLE_AS_UNKNOWN on
+
+# pngcrush
+option READ_USER_TRANSFORM on
+option WRITE_FLUSH on
+
+# pnmtopng
+chunk hIST on
+
+# cairo
+option WRITE_PACKSWAP on
+option WRITE_USER_TRANSFORM on
+
+# graphicsmagick
+option READ_USER_CHUNKS on
+
+# Qt5.15 qtgui (gentoo package split) Qt6.6 qtbase
+option READ_BGR on
+option WRITE_BGR on
+option READ_SWAP_ALPHA on
+option WRITE_SWAP_ALPHA on
+chunk oFFs on
+
+# ghostscript-gpl
+option WRITE_INVERT_ALPHA on
+option WRITE_INVERT on

contrib/conftest/fixed.dfa

@@ -0,0 +1,15 @@
+# fixed.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Test the standard libpng configuration without floating point (the internal
+# fixed point implementations are used instead).
+#
+option FLOATING_ARITHMETIC off
+option FLOATING_POINT off

contrib/conftest/float-fixed.dfa

@@ -0,0 +1,14 @@
+# fixed-float.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Test the standard libpng configuration with the fixed point internal
+# implementation in place of the default floating point
+#
+option FLOATING_ARITHMETIC off

contrib/conftest/nocompile-limits.dfa

@@ -0,0 +1,21 @@
+# nolimits.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+#
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng without any limits and without run-time settable limits.  Turning
+# USER_LIMITS off reduces libpng code size by allowing compile-time elimination
+# of some checking code.
+#
+option USER_LIMITS off
+
+@# define PNG_USER_WIDTH_MAX PNG_UINT_31_MAX
+@# define PNG_USER_HEIGHT_MAX PNG_UINT_31_MAX
+@# define PNG_USER_CHUNK_CACHE_MAX 0
+@# define PNG_USER_CHUNK_MALLOC_MAX 0

contrib/conftest/nolimits.dfa

@@ -0,0 +1,19 @@
+# nolimits.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+#
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng without any limits.  With these settigs run-time limits are still
+# possible.
+#
+@# define PNG_USER_WIDTH_MAX PNG_UINT_31_MAX
+@# define PNG_USER_HEIGHT_MAX PNG_UINT_31_MAX
+@# define PNG_USER_CHUNK_CACHE_MAX 0
+@# define PNG_USER_CHUNK_MALLOC_MAX 0
+

contrib/conftest/pngcp.dfa

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+# pngcp.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2016
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with support for pngcp.  This means just png_read_png,
+# png_write_png and small number of configuration settings.
+#
+everything = off
+
+# This option is specific to this configuration; it adds a #define to the
+# generated pnglibconf.h which turns on the (not portable) timing option for
+# pngcp.  Note that any option is automatically preceded by PNG_; there is no
+# way round this and this is deliberate.
+option PNGCP_TIMING
+
+# Because of the everything off above the option must also be turned on.  This
+# may not be done in one step because it is safer and avoids mis-spelled options
+# in user .dfa files to error out if an unrecognized option is turned on.
+option PNGCP_TIMING on
+
+# Options to turn on png_read_png and png_write_png:
+option INFO_IMAGE on
+option SEQUENTIAL_READ on
+option EASY_ACCESS on
+option WRITE on
+option WRITE_16BIT on
+option WRITE_FILTER on
+
+# pngcp needs this to preserve unknown chunks, switching all these on means that
+# pngcp can work without explicit known chunk reading support
+option UNKNOWN_CHUNKS on
+option SET_UNKNOWN_CHUNKS on
+option HANDLE_AS_UNKNOWN on
+option SAVE_UNKNOWN_CHUNKS on
+option WRITE_UNKNOWN_CHUNKS on
+
+# pngcp needs this to handle palette files with invalid indices:
+option CHECK_FOR_INVALID_INDEX on
+option GET_PALETTE_MAX on
+
+# Pre-libpng 1.7 pngcp has to stash text chunks manually, post 1.7 without this
+# text chunks should be handled as unknown ok.
+option TEXT on
+
+# this is used to turn off limits:
+option USER_LIMITS on
+option SET_USER_LIMITS on
+
+# these are just required for specific customizations
+option WRITE_CUSTOMIZE_ZTXT_COMPRESSION on
+option WRITE_CUSTOMIZE_COMPRESSION on

contrib/conftest/read-full.dfa

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+# read-full.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with no write support and full read support.
+#
+option WRITE off

contrib/conftest/read.dfa

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+# read.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with basic read support.  This enables the lowest level libpng
+# read API - the one where the calling code has to use a loop to read each row.
+# At present this is the API used by most programs.
+#
+# Support is enabled only for those chunks and transformations that are
+# typically required - others can be added easily.
+#
+
+everything = off
+
+# The sequential read code is enabled here; the progressive code can be used
+# instead but there is no point enabling both.
+
+option SEQUENTIAL_READ on
+
+# Likewise it is pointless enabling both fixed and floating point APIs.  Choose
+# one or the other for both the API and the internal math.
+
+#Fixed point:
+#option FIXED_POINT on
+#option FLOATING_ARITHMETIC off
+
+#Floating point:
+option FLOATING_POINT on
+option FLOATING_ARITHMETIC on
+
+# Basic error handling, IO and user memory support.  The latter allows the
+# application program to provide its own implementations of 'malloc' and 'free'.
+option SETJMP on
+option STDIO on
+option USER_MEM on
+
+# To read the full set of PNG images correctly interlace, transparency and
+# 16-bit support is required.  The application can implement interlace itself,
+# but very few do and it's no longer possible to disable it when READ is
+# enabled.
+option READ_tRNS on
+option READ_16BIT on
+
+# Everything else is application dependent.  This file assumes the app handles
+# all the native PNG bit layouts, so it doesn't need any of layout change
+# transforms, but needs libpng to perform gamma correction.  It doesn't do any
+# colorspace stuff and ignores the 'significant bit' information.
+#
+# If your app always expands the image to a limited set of bit layouts you
+# probably want to consider using the simplified API instead of the low level
+# one - see png.h and s_read.dfa.
+option READ_GAMMA on

contrib/conftest/s_read.dfa

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+# s_read.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with simplified read support (only).  This builds a minimal
+# libpng able to read all PNG formats and convert them into a small number of
+# well understood memory formats.
+#
+
+everything = off
+
+option SIMPLIFIED_READ on
+
+# It isn't necessary to chose fixed or floating point for the APIs because the
+# simplified API doesn't need fixed or floating point numbers.  It is necessary
+# to chose an internal math implementation.  The default (because of 'everything
+# = off') is fixed point - turn the floating point implementation on if you have
+# hardware floating point or prefer your software floating point implementation.
+option FLOATING_ARITHMETIC on
+
+# This is not strictly necessary, but without it the message strings in the API
+# will not be filled in
+option ERROR_TEXT on
+
+# Switching these options on enables the 'AFIRST' and 'BGR' formats - you don't
+# need this if you don't use them, they just allow the in-memory layout to be
+# changed to match common hardware formats.
+option SIMPLIFIED_READ_AFIRST on
+option SIMPLIFIED_READ_BGR on

contrib/conftest/s_write.dfa

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+# s_write.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with (just) simplified write support
+#
+
+everything = off
+
+option SIMPLIFIED_WRITE on
+
+# It isn't necessary to chose fixed or floating point for the APIs because the
+# simplified API doesn't need fixed or floating point numbers.  It is necessary
+# to chose an internal math implementation.  The default (because of 'everything
+# = off') is fixed point - turn the floating point implementation on if you have
+# hardware floating point or prefer your software floating point implementation.
+option FLOATING_ARITHMETIC on
+
+# This is not strictly necessary, but without it the message strings in the API
+# will not be filled in
+option ERROR_TEXT on
+
+# Switching these options on enables the 'AFIRST' and 'BGR' formats - you don't
+# need this if you don't use them, they just allow the in-memory layout to be
+# changed to match common hardware formats.
+option SIMPLIFIED_WRITE_AFIRST on
+option SIMPLIFIED_WRITE_BGR on

contrib/conftest/simple.dfa

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+# simple.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with just the simplified APIs (read and write).
+#
+
+everything = off
+
+option SIMPLIFIED_WRITE on
+option SIMPLIFIED_READ on
+
+# It isn't necessary to chose fixed or floating point for the APIs because the
+# simplified API doesn't need fixed or floating point numbers.  It is necessary
+# to chose an internal math implementation.  The default (because of 'everything
+# = off') is fixed point - turn the floating point implementation on if you have
+# hardware floating point or prefer your software floating point implementation.
+option FLOATING_ARITHMETIC on
+
+# This is not strictly necessary, but without it the message strings in the API
+# will not be filled in
+option ERROR_TEXT on
+
+# Switching these options on enables the 'AFIRST' and 'BGR' formats - you don't
+# need this if you don't use them, they just allow the in-memory layout to be
+# changed to match common hardware formats.
+option SIMPLIFIED_READ_AFIRST on
+option SIMPLIFIED_READ_BGR on
+option SIMPLIFIED_WRITE_AFIRST on
+option SIMPLIFIED_WRITE_BGR on