Release OpenCV 3.4.20

Merge pull request #23860 from fengyuentau:fix_overflow_sigmoid_v3.4
dnn: fix overflow in sigmoid layer for 3.4
2026-07-21 19:33:03 +04:00 · 2023-06-27 14:29:13 +03:00 · 2023-06-23 19:47:42 +03:00 · 2023-06-23 21:22:21 +08:00 · 2023-06-23 13:07:45 +03:00 · 2023-06-23 17:53:03 +09:00
425 changed files with 18827 additions and 6349 deletions
@@ -0,0 +1,34 @@
+name: PR:3.4
+
+on:
+  pull_request:
+    branches:
+      - 3.4
+
+jobs:
+  Ubuntu2004-ARM64:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-ARM64.yaml@main
+
+  Ubuntu1404-x64:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-U14.yaml@main
+
+  Ubuntu2004-x64:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-U20.yaml@main
+
+  Windows10-x64:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-W10.yaml@main
+
+  macOS-ARM64:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-macOS-ARM64.yaml@main
+
+  macOS-x64:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-macOS-x86_64.yaml@main
+
+  iOS:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-iOS.yaml@main
+
+  Android:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-Android.yaml@main
+
+  docs:
+    uses: opencv/ci-gha-workflow/.github/workflows/OCV-PR-3.4-docs.yaml@main
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8.11 FATAL_ERROR)
+cmake_minimum_required(VERSION ${MIN_VER_CMAKE} FATAL_ERROR)

 project(Carotene)

@@ -27,6 +27,10 @@ if(CMAKE_COMPILER_IS_GNUCC)
    endif()
 endif()

+if(APPLE AND CV_CLANG AND WITH_NEON)
+    ocv_warnings_disable(CMAKE_CXX_FLAGS -Wno-unused-function)
+endif()
+
 add_library(carotene_objs OBJECT EXCLUDE_FROM_ALL
  ${carotene_headers}
  ${carotene_sources}
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8.8 FATAL_ERROR)
+cmake_minimum_required(VERSION ${MIN_VER_CMAKE} FATAL_ERROR)

 include(CheckCCompilerFlag)
 include(CheckCXXCompilerFlag)
@@ -1296,13 +1296,13 @@ struct MorphCtx
    CAROTENE_NS::BORDER_MODE border;
    uchar borderValues[4];
 };
-inline int TEGRA_MORPHINIT(cvhalFilter2D **context, int operation, int src_type, int dst_type, int, int,
+inline int TEGRA_MORPHINIT(cvhalFilter2D **context, int operation, int src_type, int dst_type, int width, int height,
                           int kernel_type, uchar *kernel_data, size_t kernel_step, int kernel_width, int kernel_height, int anchor_x, int anchor_y,
                           int borderType, const double borderValue[4], int iterations, bool allowSubmatrix, bool allowInplace)
 {
    if(!context || !kernel_data || src_type != dst_type ||
       CV_MAT_DEPTH(src_type) != CV_8U || src_type < 0 || (src_type >> CV_CN_SHIFT) > 3 ||
-
+       width < kernel_width || height < kernel_height ||
       allowSubmatrix || allowInplace || iterations != 1 ||
       !CAROTENE_NS::isSupportedConfiguration())
        return CV_HAL_ERROR_NOT_IMPLEMENTED;
@@ -109,9 +109,9 @@ template <> struct wAdd<s32>
        vgamma = vdupq_n_f32(_gamma + 0.5);
    }

-    void operator() (const typename VecTraits<s32>::vec128 & v_src0,
-                     const typename VecTraits<s32>::vec128 & v_src1,
-                     typename VecTraits<s32>::vec128 & v_dst) const
+    void operator() (const VecTraits<s32>::vec128 & v_src0,
+                     const VecTraits<s32>::vec128 & v_src1,
+                     VecTraits<s32>::vec128 & v_dst) const
    {
        float32x4_t vs1 = vcvtq_f32_s32(v_src0);
        float32x4_t vs2 = vcvtq_f32_s32(v_src1);
@@ -121,9 +121,9 @@ template <> struct wAdd<s32>
        v_dst = vcvtq_s32_f32(vs1);
    }

-    void operator() (const typename VecTraits<s32>::vec64 & v_src0,
-                     const typename VecTraits<s32>::vec64 & v_src1,
-                     typename VecTraits<s32>::vec64 & v_dst) const
+    void operator() (const VecTraits<s32>::vec64 & v_src0,
+                     const VecTraits<s32>::vec64 & v_src1,
+                     VecTraits<s32>::vec64 & v_dst) const
    {
        float32x2_t vs1 = vcvt_f32_s32(v_src0);
        float32x2_t vs2 = vcvt_f32_s32(v_src1);
@@ -153,9 +153,9 @@ template <> struct wAdd<u32>
        vgamma = vdupq_n_f32(_gamma + 0.5);
    }

-    void operator() (const typename VecTraits<u32>::vec128 & v_src0,
-                     const typename VecTraits<u32>::vec128 & v_src1,
-                     typename VecTraits<u32>::vec128 & v_dst) const
+    void operator() (const VecTraits<u32>::vec128 & v_src0,
+                     const VecTraits<u32>::vec128 & v_src1,
+                     VecTraits<u32>::vec128 & v_dst) const
    {
        float32x4_t vs1 = vcvtq_f32_u32(v_src0);
        float32x4_t vs2 = vcvtq_f32_u32(v_src1);
@@ -165,9 +165,9 @@ template <> struct wAdd<u32>
        v_dst = vcvtq_u32_f32(vs1);
    }

-    void operator() (const typename VecTraits<u32>::vec64 & v_src0,
-                     const typename VecTraits<u32>::vec64 & v_src1,
-                     typename VecTraits<u32>::vec64 & v_dst) const
+    void operator() (const VecTraits<u32>::vec64 & v_src0,
+                     const VecTraits<u32>::vec64 & v_src1,
+                     VecTraits<u32>::vec64 & v_dst) const
    {
        float32x2_t vs1 = vcvt_f32_u32(v_src0);
        float32x2_t vs2 = vcvt_f32_u32(v_src1);
@@ -197,17 +197,17 @@ template <> struct wAdd<f32>
        vgamma = vdupq_n_f32(_gamma + 0.5);
    }

-    void operator() (const typename VecTraits<f32>::vec128 & v_src0,
-                     const typename VecTraits<f32>::vec128 & v_src1,
-                     typename VecTraits<f32>::vec128 & v_dst) const
+    void operator() (const VecTraits<f32>::vec128 & v_src0,
+                     const VecTraits<f32>::vec128 & v_src1,
+                     VecTraits<f32>::vec128 & v_dst) const
    {
        float32x4_t vs1 = vmlaq_f32(vgamma, v_src0, valpha);
        v_dst = vmlaq_f32(vs1, v_src1, vbeta);
    }

-    void operator() (const typename VecTraits<f32>::vec64 & v_src0,
-                     const typename VecTraits<f32>::vec64 & v_src1,
-                     typename VecTraits<f32>::vec64 & v_dst) const
+    void operator() (const VecTraits<f32>::vec64 & v_src0,
+                     const VecTraits<f32>::vec64 & v_src1,
+                     VecTraits<f32>::vec64 & v_dst) const
    {
        float32x2_t vs1 = vmla_f32(vget_low(vgamma), v_src0, vget_low(valpha));
        v_dst = vmla_f32(vs1, v_src1, vget_low(vbeta));
@@ -1,8 +1,8 @@
-# Binaries branch name: ffmpeg/3.4_20211220
-# Binaries were created for OpenCV: a22dd28e0272ec0f1cfee8811d3f5f0392827c65
-ocv_update(FFMPEG_BINARIES_COMMIT "5a7644ec3940c6eed41c6ebb5a0602a5615fdb3f")
-ocv_update(FFMPEG_FILE_HASH_BIN32 "8ad9de6f1f2ca77786748d1f3a4e83ea")
-ocv_update(FFMPEG_FILE_HASH_BIN64 "2c670f068252e7cd28d3883993dc1d6e")
+# Binaries branch name: 3.4_20230620
+# Binaries were created for OpenCV: c97c22b7cf2ef0f82cd4203a2e9a6eda94e9f7f1
+ocv_update(FFMPEG_BINARIES_COMMIT "7c4bb90fd43a13732ae907981a88fb983a7e2197")
+ocv_update(FFMPEG_FILE_HASH_BIN32 "d7db86de29b0460294489c5ed3180b56")
+ocv_update(FFMPEG_FILE_HASH_BIN64 "9df93d8afff2eee368ad484098a12b18")
 ocv_update(FFMPEG_FILE_HASH_CMAKE "3b90f67f4b429e77d3da36698cef700c")

 function(download_win_ffmpeg script_var)
@@ -2,32 +2,32 @@ function(download_ippicv root_var)
  set(${root_var} "" PARENT_SCOPE)

  # Commit SHA in the opencv_3rdparty repo
-  set(IPPICV_COMMIT "a56b6ac6f030c312b2dce17430eef13aed9af274")
+  set(IPPICV_COMMIT "1224f78da6684df04397ac0f40c961ed37f79ccb")
  # Define actual ICV versions
  if(APPLE)
    set(OPENCV_ICV_PLATFORM "macosx")
    set(OPENCV_ICV_PACKAGE_SUBDIR "ippicv_mac")
-    set(OPENCV_ICV_NAME "ippicv_2020_mac_intel64_20191018_general.tgz")
-    set(OPENCV_ICV_HASH "1c3d675c2a2395d094d523024896e01b")
+    set(OPENCV_ICV_NAME "ippicv_2021.8_mac_intel64_20230330_general.tgz")
+    set(OPENCV_ICV_HASH "d2b234a86af1b616958619a4560356d9")
  elseif((UNIX AND NOT ANDROID) OR (UNIX AND ANDROID_ABI MATCHES "x86"))
    set(OPENCV_ICV_PLATFORM "linux")
    set(OPENCV_ICV_PACKAGE_SUBDIR "ippicv_lnx")
    if(X86_64)
-      set(OPENCV_ICV_NAME "ippicv_2020_lnx_intel64_20191018_general.tgz")
-      set(OPENCV_ICV_HASH "7421de0095c7a39162ae13a6098782f9")
+      set(OPENCV_ICV_NAME "ippicv_2021.8_lnx_intel64_20230330_general.tgz")
+      set(OPENCV_ICV_HASH "43219bdc7e3805adcbe3a1e2f1f3ef3b")
    else()
-      set(OPENCV_ICV_NAME "ippicv_2020_lnx_ia32_20191018_general.tgz")
-      set(OPENCV_ICV_HASH "ad189a940fb60eb71f291321322fe3e8")
+      set(OPENCV_ICV_NAME "ippicv_2021.8_lnx_ia32_20230330_general.tgz")
+      set(OPENCV_ICV_HASH "165875443d72faa3fd2146869da90d07")
    endif()
  elseif(WIN32 AND NOT ARM)
    set(OPENCV_ICV_PLATFORM "windows")
    set(OPENCV_ICV_PACKAGE_SUBDIR "ippicv_win")
    if(X86_64)
-      set(OPENCV_ICV_NAME "ippicv_2020_win_intel64_20191018_general.zip")
-      set(OPENCV_ICV_HASH "879741a7946b814455eee6c6ffde2984")
+      set(OPENCV_ICV_NAME "ippicv_2021.8_win_intel64_20230330_general.zip")
+      set(OPENCV_ICV_HASH "71e4f58de939f0348ec7fb58ffb17dbf")
    else()
-      set(OPENCV_ICV_NAME "ippicv_2020_win_ia32_20191018_general.zip")
-      set(OPENCV_ICV_HASH "cd39bdf0c2e1cac9a61101dad7a2413e")
+      set(OPENCV_ICV_NAME "ippicv_2021.8_win_ia32_20230330_general.zip")
+      set(OPENCV_ICV_HASH "57fd4648cfe64eae9e2ad9d50173a553")
    endif()
  else()
    return()
@@ -66,6 +66,11 @@ if(PPC64LE OR PPC64)
  endif()
 endif()

+if(APPLE AND CV_CLANG AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 13.1)
+  ocv_warnings_disable(CMAKE_C_FLAGS -Wnull-pointer-subtraction)
+  ocv_warnings_disable(CMAKE_C_FLAGS -Wunused-but-set-variable)
+endif()
+
 # ----------------------------------------------------------------------------------
 #         Define the library target:
 # ----------------------------------------------------------------------------------
@@ -77,7 +82,9 @@ endif(MSVC)
 add_library(${PNG_LIBRARY} STATIC ${OPENCV_3RDPARTY_EXCLUDE_FROM_ALL} ${lib_srcs} ${lib_hdrs})
 target_link_libraries(${PNG_LIBRARY} ${ZLIB_LIBRARIES})

-ocv_warnings_disable(CMAKE_C_FLAGS -Wundef -Wcast-align -Wimplicit-fallthrough -Wunused-parameter -Wsign-compare)
+ocv_warnings_disable(CMAKE_C_FLAGS -Wundef -Wcast-align -Wimplicit-fallthrough -Wunused-parameter -Wsign-compare
+    -Wmaybe-uninitialized
+)

 set_target_properties(${PNG_LIBRARY}
  PROPERTIES OUTPUT_NAME ${PNG_LIBRARY}
@@ -452,8 +452,9 @@ ocv_warnings_disable(CMAKE_C_FLAGS -Wno-unused-but-set-variable -Wmissing-protot
                                   -Wcast-align -Wshadow -Wno-maybe-uninitialized -Wno-pointer-to-int-cast -Wno-int-to-pointer-cast
                                   -Wmisleading-indentation
                                   -Wimplicit-fallthrough
+                                   -Wunused-parameter  # clang
+                                   -Warray-parameter
 )
-ocv_warnings_disable(CMAKE_C_FLAGS -Wunused-parameter) # clang
 ocv_warnings_disable(CMAKE_CXX_FLAGS -Wmissing-declarations -Wunused-parameter -Wmissing-prototypes
    -Wundef  # tiffiop.h: #if __clang_major__ >= 4
 )
@@ -119,6 +119,7 @@ ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4334) # vs2005 Win64
 ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4244) # vs2008
 ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4267) # vs2008 Win64
 ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4456) # vs2015
+ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4819) # vs2019 Win64

 if(MSVC AND CV_ICC)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Qrestrict")
@@ -77,7 +77,7 @@ E.g. external ref-counting is implemented for 1.0 version and native OpenVX one

 Also there are some **C++ 11** features are used (e.g. rvalue ref-s) when their availability is detected at ***compile time***.

-C++ exceptions are used for errors indication instead of return codes. There are two types of exceptions are defined:  `RuntimeError` is thrown when OpenVX C call returned unsuccessful result and `WrapperError` is thrown when a problem is occured in the wrappers code. Both exception calsses are derived from `std::exception` (actually from its inheritants).
+C++ exceptions are used for errors indication instead of return codes. There are two types of exceptions are defined:  `RuntimeError` is thrown when OpenVX C call returned unsuccessful result and `WrapperError` is thrown when a problem is occurred in the wrappers code. Both exception calsses are derived from `std::exception` (actually from its inheritants).

 The so called **OpenVX objects** (e.g. `vx_image`) are represented as C++ classes in wrappers.
 All these classes use automatic ref-counting that allows development of exception-safe code.
@@ -37,7 +37,7 @@ libtiff               Tag Image File Format (TIFF) Software
                      WITH_TIFF CMake option must be ON to add libtiff & zlib support to imgcodecs.
 ------------------------------------------------------------------------------------
 zlib                  General purpose LZ77 compression library
-                      Copyright (C) 1995-2012 Jean-loup Gailly and Mark Adler.
+                      Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler.
                      See zlib home page http://www.zlib.net
                      for details and links to the source code
 ------------------------------------------------------------------------------------
@@ -170,4 +170,4 @@ ocv_install_target(tbb EXPORT OpenCVModules

 ocv_install_3rdparty_licenses(tbb "${tbb_src_dir}/LICENSE" "${tbb_src_dir}/README")

-ocv_tbb_read_version("${tbb_src_dir}/include")
+ocv_tbb_read_version("${tbb_src_dir}/include" tbb)
@@ -83,6 +83,7 @@ ocv_warnings_disable(CMAKE_C_FLAGS -Wshorten-64-to-32 -Wattributes -Wstrict-prot
    -Wundef  # _LFS64_LARGEFILE is not defined
    /wd4267  # MSVS 2015 (x64) + zlib 1.2.11
    -Wimplicit-fallthrough
+    /wd4244  # MSVS + zlib 1.2.12: warning C4244: '=': conversion from 'ush' to 'uchf', possible loss of data
 )

 set_target_properties(${ZLIB_LIBRARY} PROPERTIES
@@ -101,4 +102,4 @@ if(NOT BUILD_SHARED_LIBS)
  ocv_install_target(${ZLIB_LIBRARY} EXPORT OpenCVModules ARCHIVE DESTINATION ${OPENCV_3P_LIB_INSTALL_PATH} COMPONENT dev)
 endif()

-ocv_install_3rdparty_licenses(zlib README)
+ocv_install_3rdparty_licenses(zlib LICENSE)
@@ -1,6 +1,81 @@

                ChangeLog file for zlib

+Changes in 1.2.13 (13 Oct 2022)
+- Fix configure issue that discarded provided CC definition
+- Correct incorrect inputs provided to the CRC functions
+- Repair prototypes and exporting of new CRC functions
+- Fix inflateBack to detect invalid input with distances too far
+- Have infback() deliver all of the available output up to any error
+- Fix a bug when getting a gzip header extra field with inflate()
+- Fix bug in block type selection when Z_FIXED used
+- Tighten deflateBound bounds
+- Remove deleted assembler code references
+- Various portability and appearance improvements
+
+Changes in 1.2.12 (27 Mar 2022)
+- Cygwin does not have _wopen(), so do not create gzopen_w() there
+- Permit a deflateParams() parameter change as soon as possible
+- Limit hash table inserts after switch from stored deflate
+- Fix bug when window full in deflate_stored()
+- Fix CLEAR_HASH macro to be usable as a single statement
+- Avoid a conversion error in gzseek when off_t type too small
+- Have Makefile return non-zero error code on test failure
+- Avoid some conversion warnings in gzread.c and gzwrite.c
+- Update use of errno for newer Windows CE versions
+- Small speedup to inflate [psumbera]
+- Return an error if the gzputs string length can't fit in an int
+- Add address checking in clang to -w option of configure
+- Don't compute check value for raw inflate if asked to validate
+- Handle case where inflateSync used when header never processed
+- Avoid the use of ptrdiff_t
+- Avoid an undefined behavior of memcpy() in gzappend()
+- Avoid undefined behaviors of memcpy() in gz*printf()
+- Avoid an undefined behavior of memcpy() in _tr_stored_block()
+- Make the names in functions declarations identical to definitions
+- Remove old assembler code in which bugs have manifested
+- Fix deflateEnd() to not report an error at start of raw deflate
+- Add legal disclaimer to README
+- Emphasize the need to continue decompressing gzip members
+- Correct the initialization requirements for deflateInit2()
+- Fix a bug that can crash deflate on some input when using Z_FIXED
+- Assure that the number of bits for deflatePrime() is valid
+- Use a structure to make globals in enough.c evident
+- Use a macro for the printf format of big_t in enough.c
+- Clean up code style in enough.c, update version
+- Use inline function instead of macro for index in enough.c
+- Clarify that prefix codes are counted in enough.c
+- Show all the codes for the maximum tables size in enough.c
+- Add gznorm.c example, which normalizes gzip files
+- Fix the zran.c example to work on a multiple-member gzip file
+- Add tables for crc32_combine(), to speed it up by a factor of 200
+- Add crc32_combine_gen() and crc32_combine_op() for fast combines
+- Speed up software CRC-32 computation by a factor of 1.5 to 3
+- Use atomic test and set, if available, for dynamic CRC tables
+- Don't bother computing check value after successful inflateSync()
+- Correct comment in crc32.c
+- Add use of the ARMv8 crc32 instructions when requested
+- Use ARM crc32 instructions if the ARM architecture has them
+- Explicitly note that the 32-bit check values are 32 bits
+- Avoid adding empty gzip member after gzflush with Z_FINISH
+- Fix memory leak on error in gzlog.c
+- Fix error in comment on the polynomial representation of a byte
+- Clarify gz* function interfaces, referring to parameter names
+- Change macro name in inflate.c to avoid collision in VxWorks
+- Correct typo in blast.c
+- Improve portability of contrib/minizip
+- Fix indentation in minizip's zip.c
+- Replace black/white with allow/block. (theresa-m)
+- minizip warning fix if MAXU32 already defined. (gvollant)
+- Fix unztell64() in minizip to work past 4GB. (Daniël Hörchner)
+- Clean up minizip to reduce warnings for testing
+- Add fallthrough comments for gcc
+- Eliminate use of ULL constants
+- Separate out address sanitizing from warnings in configure
+- Remove destructive aspects of make distclean
+- Check for cc masquerading as gcc or clang in configure
+- Fix crc32.c to compile local functions only if used
+
 Changes in 1.2.11 (15 Jan 2017)
 - Fix deflate stored bug when pulling last block from window
 - Permit immediate deflateParams changes before any deflate input
@@ -96,7 +171,7 @@ Changes in 1.2.7.1 (24 Mar 2013)
 - Fix types in contrib/minizip to match result of get_crc_table()
 - Simplify contrib/vstudio/vc10 with 'd' suffix
 - Add TOP support to win32/Makefile.msc
- Suport i686 and amd64 assembler builds in CMakeLists.txt
+- Support i686 and amd64 assembler builds in CMakeLists.txt
 - Fix typos in the use of _LARGEFILE64_SOURCE in zconf.h
 - Add vc11 and vc12 build files to contrib/vstudio
 - Add gzvprintf() as an undocumented function in zlib
@@ -296,14 +371,14 @@ Changes in 1.2.5.1 (10 Sep 2011)
 - Use u4 type for crc_table to avoid conversion warnings
 - Apply casts in zlib.h to avoid conversion warnings
 - Add OF to prototypes for adler32_combine_ and crc32_combine_ [Miller]
- Improve inflateSync() documentation to note indeterminancy
+- Improve inflateSync() documentation to note indeterminacy
 - Add deflatePending() function to return the amount of pending output
 - Correct the spelling of "specification" in FAQ [Randers-Pehrson]
 - Add a check in configure for stdarg.h, use for gzprintf()
 - Check that pointers fit in ints when gzprint() compiled old style
 - Add dummy name before $(SHAREDLIBV) in Makefile [Bar-Lev, Bowler]
 - Delete line in configure that adds -L. libz.a to LDFLAGS [Weigelt]
- Add debug records in assmebler code [Londer]
+- Add debug records in assembler code [Londer]
 - Update RFC references to use http://tools.ietf.org/html/... [Li]
 - Add --archs option, use of libtool to configure for Mac OS X [Borstel]

@@ -511,7 +586,7 @@ Changes in 1.2.3.5 (8 Jan 2010)
 - Don't use _vsnprintf on later versions of MSVC [Lowman]
 - Add CMake build script and input file [Lowman]
 - Update contrib/minizip to 1.1 [Svensson, Vollant]
- Moved nintendods directory from contrib to .
+- Moved nintendods directory from contrib to root
 - Replace gzio.c with a new set of routines with the same functionality
 - Add gzbuffer(), gzoffset(), gzclose_r(), gzclose_w() as part of above
 - Update contrib/minizip to 1.1b
@@ -685,7 +760,7 @@ Changes in 1.2.2.4 (11 July 2005)
 - Be more strict on incomplete code sets in inflate_table() and increase
  ENOUGH and MAXD -- this repairs a possible security vulnerability for
  invalid inflate input.  Thanks to Tavis Ormandy and Markus Oberhumer for
-  discovering the vulnerability and providing test cases.
+  discovering the vulnerability and providing test cases
 - Add ia64 support to configure for HP-UX [Smith]
 - Add error return to gzread() for format or i/o error [Levin]
 - Use malloc.h for OS/2 [Necasek]
@@ -721,7 +796,7 @@ Changes in 1.2.2.2 (30 December 2004)
 - Add Z_FIXED strategy option to deflateInit2() to force fixed trees
 - Add updated make_vms.com [Coghlan], update README
 - Create a new "examples" directory, move gzappend.c there, add zpipe.c,
-  fitblk.c, gzlog.[ch], gzjoin.c, and zlib_how.html.
+  fitblk.c, gzlog.[ch], gzjoin.c, and zlib_how.html
 - Add FAQ entry and comments in deflate.c on uninitialized memory access
 - Add Solaris 9 make options in configure [Gilbert]
 - Allow strerror() usage in gzio.c for STDC
@@ -792,7 +867,7 @@ Changes in 1.2.1.1 (9 January 2004)
 - Fix a big fat bug in inftrees.c that prevented decoding valid
  dynamic blocks with only literals and no distance codes --
  Thanks to "Hot Emu" for the bug report and sample file
- Add a note to puff.c on no distance codes case.
+- Add a note to puff.c on no distance codes case

 Changes in 1.2.1 (17 November 2003)
 - Remove a tab in contrib/gzappend/gzappend.c
@@ -970,7 +1045,7 @@ Changes in 1.2.0.1 (17 March 2003)
    - Include additional header file on VMS for off_t typedef
 - Try to use _vsnprintf where it supplants vsprintf [Vollant]
 - Add some casts in inffast.c
- Enchance comments in zlib.h on what happens if gzprintf() tries to
+- Enhance comments in zlib.h on what happens if gzprintf() tries to
  write more than 4095 bytes before compression
 - Remove unused state from inflateBackEnd()
 - Remove exit(0) from minigzip.c, example.c
@@ -1036,14 +1111,14 @@ Changes in 1.2.0 (9 March 2003)
 - Add contrib/puff/ simple inflate for deflate format description

 Changes in 1.1.4 (11 March 2002)
- ZFREE was repeated on same allocation on some error conditions.
+- ZFREE was repeated on same allocation on some error conditions
  This creates a security problem described in
  http://www.zlib.org/advisory-2002-03-11.txt
 - Returned incorrect error (Z_MEM_ERROR) on some invalid data
 - Avoid accesses before window for invalid distances with inflate window
-  less than 32K.
+  less than 32K
 - force windowBits > 8 to avoid a bug in the encoder for a window size
-  of 256 bytes. (A complete fix will be available in 1.1.5).
+  of 256 bytes. (A complete fix will be available in 1.1.5)

 Changes in 1.1.3 (9 July 1998)
 - fix "an inflate input buffer bug that shows up on rare but persistent
@@ -1117,7 +1192,7 @@ Changes in 1.1.1 (27 Feb 98)
 - remove block truncation heuristic which had very marginal effect for zlib
  (smaller lit_bufsize than in gzip 1.2.4) and degraded a little the
  compression ratio on some files. This also allows inlining _tr_tally for
-  matches in deflate_slow.
+  matches in deflate_slow
 - added msdos/Makefile.w32 for WIN32 Microsoft Visual C++ (Bob Frazier)

 Changes in 1.1.0 (24 Feb 98)
@@ -1148,7 +1223,7 @@ Changes in 1.0.9 (17 Feb 1998)
 - Avoid gcc 2.8.0 comparison bug a little differently than zlib 1.0.8
 - in inftrees.c, avoid cc -O bug on HP (Farshid Elahi)
 - in zconf.h move the ZLIB_DLL stuff earlier to avoid problems with
-  the declaration of FAR (Gilles VOllant)
+  the declaration of FAR (Gilles Vollant)
 - install libz.so* with mode 755 (executable) instead of 644 (Marc Lehmann)
 - read_buf buf parameter of type Bytef* instead of charf*
 - zmemcpy parameters are of type Bytef*, not charf* (Joseph Strout)
@@ -1162,7 +1237,7 @@ Changes in 1.0.8 (27 Jan 1998)
 - include sys/types.h to get off_t on some systems (Marc Lehmann & QingLong)
 - use constant arrays for the static trees in trees.c instead of computing
  them at run time (thanks to Ken Raeburn for this suggestion). To create
-  trees.h, compile with GEN_TREES_H and run "make test".
+  trees.h, compile with GEN_TREES_H and run "make test"
 - check return code of example in "make test" and display result
 - pass minigzip command line options to file_compress
 - simplifying code of inflateSync to avoid gcc 2.8 bug
@@ -1201,12 +1276,12 @@ Changes in 1.0.6 (19 Jan 1998)
 - add functions gzprintf, gzputc, gzgetc, gztell, gzeof, gzseek, gzrewind and
  gzsetparams (thanks to Roland Giersig and Kevin Ruland for some of this code)
 - Fix a deflate bug occurring only with compression level 0 (thanks to
-  Andy Buckler for finding this one).
- In minigzip, pass transparently also the first byte for .Z files.
+  Andy Buckler for finding this one)
+- In minigzip, pass transparently also the first byte for .Z files
 - return Z_BUF_ERROR instead of Z_OK if output buffer full in uncompress()
 - check Z_FINISH in inflate (thanks to Marc Schluper)
 - Implement deflateCopy (thanks to Adam Costello)
- make static libraries by default in configure, add --shared option.
+- make static libraries by default in configure, add --shared option
 - move MSDOS or Windows specific files to directory msdos
 - suppress the notion of partial flush to simplify the interface
  (but the symbol Z_PARTIAL_FLUSH is kept for compatibility with 1.0.4)
@@ -1218,7 +1293,7 @@ Changes in 1.0.6 (19 Jan 1998)
 - added Makefile.nt (thanks to Stephen Williams)
 - added the unsupported "contrib" directory:
   contrib/asm386/ by Gilles Vollant <info@winimage.com>
-        386 asm code replacing longest_match().
+        386 asm code replacing longest_match()
   contrib/iostream/ by Kevin Ruland <kevin@rodin.wustl.edu>
        A C++ I/O streams interface to the zlib gz* functions
   contrib/iostream2/  by Tyge Løvset <Tyge.Lovset@cmr.no>
@@ -1226,7 +1301,7 @@ Changes in 1.0.6 (19 Jan 1998)
   contrib/untgz/  by "Pedro A. Aranda Guti\irrez" <paag@tid.es>
        A very simple tar.gz file extractor using zlib
   contrib/visual-basic.txt by Carlos Rios <c_rios@sonda.cl>
-        How to use compress(), uncompress() and the gz* functions from VB.
+        How to use compress(), uncompress() and the gz* functions from VB
 - pass params -f (filtered data), -h (huffman only), -1 to -9 (compression
  level) in minigzip (thanks to Tom Lane)

@@ -1235,8 +1310,8 @@ Changes in 1.0.6 (19 Jan 1998)
 - add undocumented function inflateSyncPoint() (hack for Paul Mackerras)
 - add undocumented function zError to convert error code to string
  (for Tim Smithers)
- Allow compilation of gzio with -DNO_DEFLATE to avoid the compression code.
- Use default memcpy for Symantec MSDOS compiler.
+- Allow compilation of gzio with -DNO_DEFLATE to avoid the compression code
+- Use default memcpy for Symantec MSDOS compiler
 - Add EXPORT keyword for check_func (needed for Windows DLL)
 - add current directory to LD_LIBRARY_PATH for "make test"
 - create also a link for libz.so.1
@@ -1249,7 +1324,7 @@ Changes in 1.0.6 (19 Jan 1998)
 - allow compilation with ANSI keywords only enabled for TurboC in large model
 - avoid "versionString"[0] (Borland bug)
 - add NEED_DUMMY_RETURN for Borland
- use variable z_verbose for tracing in debug mode (L. Peter Deutsch).
+- use variable z_verbose for tracing in debug mode (L. Peter Deutsch)
 - allow compilation with CC
 - defined STDC for OS/2 (David Charlap)
 - limit external names to 8 chars for MVS (Thomas Lund)
@@ -1259,7 +1334,7 @@ Changes in 1.0.6 (19 Jan 1998)
 - use _fdopen instead of fdopen for MSC >= 6.0 (Thomas Fanslau)
 - added makelcc.bat for lcc-win32 (Tom St Denis)
 - in Makefile.dj2, use copy and del instead of install and rm (Frank Donahoe)
- Avoid expanded $Id$. Use "rcs -kb" or "cvs admin -kb" to avoid Id expansion.
+- Avoid expanded $Id$. Use "rcs -kb" or "cvs admin -kb" to avoid Id expansion
 - check for unistd.h in configure (for off_t)
 - remove useless check parameter in inflate_blocks_free
 - avoid useless assignment of s->check to itself in inflate_blocks_new
@@ -1280,7 +1355,7 @@ Changes in 1.0.5 (3 Jan 98)
 Changes in 1.0.4 (24 Jul 96)
 - In very rare conditions, deflate(s, Z_FINISH) could fail to produce an EOF
  bit, so the decompressor could decompress all the correct data but went
-  on to attempt decompressing extra garbage data. This affected minigzip too.
+  on to attempt decompressing extra garbage data. This affected minigzip too
 - zlibVersion and gzerror return const char* (needed for DLL)
 - port to RISCOS (no fdopen, no multiple dots, no unlink, no fileno)
 - use z_error only for DEBUG (avoid problem with DLLs)
@@ -1310,7 +1385,7 @@ Changes in 1.0.1 (20 May 96) [1.0 skipped to avoid confusion]
 - fix array overlay in deflate.c which sometimes caused bad compressed data
 - fix inflate bug with empty stored block
 - fix MSDOS medium model which was broken in 0.99
- fix deflateParams() which could generate bad compressed data.
+- fix deflateParams() which could generate bad compressed data
 - Bytef is define'd instead of typedef'ed (work around Borland bug)
 - added an INDEX file
 - new makefiles for DJGPP (Makefile.dj2), 32-bit Borland (Makefile.b32),
@@ -1331,7 +1406,7 @@ Changes in 0.99 (27 Jan 96)
 - allow preset dictionary shared between compressor and decompressor
 - allow compression level 0 (no compression)
 - add deflateParams in zlib.h: allow dynamic change of compression level
-  and compression strategy.
+  and compression strategy
 - test large buffers and deflateParams in example.c
 - add optional "configure" to build zlib as a shared library
 - suppress Makefile.qnx, use configure instead
@@ -1373,30 +1448,30 @@ Changes in 0.99 (27 Jan 96)
 - use STDC instead of __GO32__ to avoid redeclaring exit, calloc, etc...
 - use Z_BINARY instead of BINARY
 - document that gzclose after gzdopen will close the file
- allow "a" as mode in gzopen.
+- allow "a" as mode in gzopen
 - fix error checking in gzread
 - allow skipping .gz extra-field on pipes
 - added reference to Perl interface in README
 - put the crc table in FAR data (I dislike more and more the medium model :)
 - added get_crc_table
- added a dimension to all arrays (Borland C can't count).
+- added a dimension to all arrays (Borland C can't count)
 - workaround Borland C bug in declaration of inflate_codes_new & inflate_fast
 - guard against multiple inclusion of *.h (for precompiled header on Mac)
- Watcom C pretends to be Microsoft C small model even in 32 bit mode.
+- Watcom C pretends to be Microsoft C small model even in 32 bit mode
 - don't use unsized arrays to avoid silly warnings by Visual C++:
     warning C4746: 'inflate_mask' : unsized array treated as  '__far'
-     (what's wrong with far data in far model?).
+     (what's wrong with far data in far model?)
 - define enum out of inflate_blocks_state to allow compilation with C++

 Changes in 0.95 (16 Aug 95)
 - fix MSDOS small and medium model (now easier to adapt to any compiler)
 - inlined send_bits
 - fix the final (:-) bug for deflate with flush (output was correct but
-  not completely flushed in rare occasions).
+  not completely flushed in rare occasions)
 - default window size is same for compression and decompression
-  (it's now sufficient to set MAX_WBITS in zconf.h).
+  (it's now sufficient to set MAX_WBITS in zconf.h)
 - voidp -> voidpf and voidnp -> voidp (for consistency with other
-  typedefs and because voidnp was not near in large model).
+  typedefs and because voidnp was not near in large model)

 Changes in 0.94 (13 Aug 95)
 - support MSDOS medium model
@@ -1405,12 +1480,12 @@ Changes in 0.94 (13 Aug 95)
 - added support for VMS
 - allow a compression level in gzopen()
 - gzflush now calls fflush
- For deflate with flush, flush even if no more input is provided.
+- For deflate with flush, flush even if no more input is provided
 - rename libgz.a as libz.a
 - avoid complex expression in infcodes.c triggering Turbo C bug
 - work around a problem with gcc on Alpha (in INSERT_STRING)
 - don't use inline functions (problem with some gcc versions)
- allow renaming of Byte, uInt, etc... with #define.
+- allow renaming of Byte, uInt, etc... with #define
 - avoid warning about (unused) pointer before start of array in deflate.c
 - avoid various warnings in gzio.c, example.c, infblock.c, adler32.c, zutil.c
 - avoid reserved word 'new' in trees.c
@@ -1429,7 +1504,7 @@ Changes in 0.92 (3 May 95)
 - no memcpy on Pyramid
 - suppressed inftest.c
 - optimized fill_window, put longest_match inline for gcc
- optimized inflate on stored blocks.
+- optimized inflate on stored blocks
 - untabify all sources to simplify patches

 Changes in 0.91 (2 May 95)
@@ -1447,7 +1522,7 @@ Changes in 0.9 (1 May 95)
 - let again gzread copy uncompressed data unchanged (was working in 0.71)
 - deflate(Z_FULL_FLUSH), inflateReset and inflateSync are now fully implemented
 - added a test of inflateSync in example.c
- moved MAX_WBITS to zconf.h because users might want to change that.
+- moved MAX_WBITS to zconf.h because users might want to change that
 - document explicitly that zalloc(64K) on MSDOS must return a normalized
  pointer (zero offset)
 - added Makefiles for Microsoft C, Turbo C, Borland C++
@@ -1456,7 +1531,7 @@ Changes in 0.9 (1 May 95)
 Changes in 0.8 (29 April 95)
 - added fast inflate (inffast.c)
 - deflate(Z_FINISH) now returns Z_STREAM_END when done. Warning: this
-  is incompatible with previous versions of zlib which returned Z_OK.
+  is incompatible with previous versions of zlib which returned Z_OK
 - work around a TurboC compiler bug (bad code for b << 0, see infutil.h)
  (actually that was not a compiler bug, see 0.81 above)
 - gzread no longer reads one extra byte in certain cases
@@ -1466,50 +1541,50 @@ Changes in 0.8 (29 April 95)

 Changes in 0.71 (14 April 95)
 - Fixed more MSDOS compilation problems :( There is still a bug with
-  TurboC large model.
+  TurboC large model

 Changes in 0.7 (14 April 95)
- Added full inflate support.
+- Added full inflate support
 - Simplified the crc32() interface. The pre- and post-conditioning
  (one's complement) is now done inside crc32(). WARNING: this is
-  incompatible with previous versions; see zlib.h for the new usage.
+  incompatible with previous versions; see zlib.h for the new usage

 Changes in 0.61 (12 April 95)
- workaround for a bug in TurboC. example and minigzip now work on MSDOS.
+- workaround for a bug in TurboC. example and minigzip now work on MSDOS

 Changes in 0.6 (11 April 95)
 - added minigzip.c
 - added gzdopen to reopen a file descriptor as gzFile
- added transparent reading of non-gziped files in gzread.
+- added transparent reading of non-gziped files in gzread
 - fixed bug in gzread (don't read crc as data)
- fixed bug in destroy (gzio.c) (don't return Z_STREAM_END for gzclose).
+- fixed bug in destroy (gzio.c) (don't return Z_STREAM_END for gzclose)
 - don't allocate big arrays in the stack (for MSDOS)
 - fix some MSDOS compilation problems

 Changes in 0.5:
 - do real compression in deflate.c. Z_PARTIAL_FLUSH is supported but
-  not yet Z_FULL_FLUSH.
+  not yet Z_FULL_FLUSH
 - support decompression but only in a single step (forced Z_FINISH)
- added opaque object for zalloc and zfree.
+- added opaque object for zalloc and zfree
 - added deflateReset and inflateReset
- added a variable zlib_version for consistency checking.
- renamed the 'filter' parameter of deflateInit2 as 'strategy'.
-  Added Z_FILTERED and Z_HUFFMAN_ONLY constants.
+- added a variable zlib_version for consistency checking
+- renamed the 'filter' parameter of deflateInit2 as 'strategy'
+  Added Z_FILTERED and Z_HUFFMAN_ONLY constants

 Changes in 0.4:
- avoid "zip" everywhere, use zlib instead of ziplib.
+- avoid "zip" everywhere, use zlib instead of ziplib
 - suppress Z_BLOCK_FLUSH, interpret Z_PARTIAL_FLUSH as block flush
-  if compression method == 8.
+  if compression method == 8
 - added adler32 and crc32
 - renamed deflateOptions as deflateInit2, call one or the other but not both
- added the method parameter for deflateInit2.
+- added the method parameter for deflateInit2
 - added inflateInit2
- simplied considerably deflateInit and inflateInit by not supporting
+- simplified considerably deflateInit and inflateInit by not supporting
  user-provided history buffer. This is supported only in deflateInit2
-  and inflateInit2.
+  and inflateInit2

 Changes in 0.3:
 - prefix all macro names with Z_
- use Z_FINISH instead of deflateEnd to finish compression.
+- use Z_FINISH instead of deflateEnd to finish compression
 - added Z_HUFFMAN_ONLY
 - added gzerror()
@@ -0,0 +1,22 @@
+Copyright notice:
+
+ (C) 1995-2022 Jean-loup Gailly and Mark Adler
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  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 notice may not be removed or altered from any source distribution.
+
+  Jean-loup Gailly        Mark Adler
+  jloup@gzip.org          madler@alumni.caltech.edu
@@ -1,6 +1,6 @@
 ZLIB DATA COMPRESSION LIBRARY

-zlib 1.2.11 is a general purpose data compression library.  All the code is
+zlib 1.2.13 is a general purpose data compression library.  All the code is
 thread safe.  The data format used by the zlib library is described by RFCs
 (Request for Comments) 1950 to 1952 in the files
 http://tools.ietf.org/html/rfc1950 (zlib format), rfc1951 (deflate format) and
@@ -31,7 +31,7 @@ Mark Nelson <markn@ieee.org> wrote an article about zlib for the Jan.  1997
 issue of Dr.  Dobb's Journal; a copy of the article is available at
 http://marknelson.us/1997/01/01/zlib-engine/ .

-The changes made in version 1.2.11 are documented in the file ChangeLog.
+The changes made in version 1.2.13 are documented in the file ChangeLog.

 Unsupported third party contributions are provided in directory contrib/ .

@@ -84,7 +84,7 @@ Acknowledgments:

 Copyright notice:

- (C) 1995-2017 Jean-loup Gailly and Mark Adler
+ (C) 1995-2022 Jean-loup Gailly and Mark Adler

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
@@ -108,7 +108,10 @@ Copyright notice:
 If you use the zlib library in a product, we would appreciate *not* receiving
 lengthy legal documents to sign.  The sources are provided for free but without
 warranty of any kind.  The library has been entirely written by Jean-loup
-Gailly and Mark Adler; it does not include third-party code.
+Gailly and Mark Adler; it does not include third-party code.  We make all
+contributions to and distributions of this project solely in our personal
+capacity, and are not conveying any rights to any intellectual property of
+any third parties.

 If you redistribute modified sources, we would appreciate that you include in
 the file ChangeLog history information documenting your changes.  Please read
@@ -19,7 +19,7 @@
   memory, Z_BUF_ERROR if there was not enough room in the output buffer,
   Z_STREAM_ERROR if the level parameter is invalid.
 */
-int ZEXPORT compress2 (dest, destLen, source, sourceLen, level)
+int ZEXPORT compress2(dest, destLen, source, sourceLen, level)
    Bytef *dest;
    uLongf *destLen;
    const Bytef *source;
@@ -65,7 +65,7 @@ int ZEXPORT compress2 (dest, destLen, source, sourceLen, level)

 /* ===========================================================================
 */
-int ZEXPORT compress (dest, destLen, source, sourceLen)
+int ZEXPORT compress(dest, destLen, source, sourceLen)
    Bytef *dest;
    uLongf *destLen;
    const Bytef *source;
@@ -78,7 +78,7 @@ int ZEXPORT compress (dest, destLen, source, sourceLen)
     If the default memLevel or windowBits for deflateInit() is changed, then
   this function needs to be updated.
 */
-uLong ZEXPORT compressBound (sourceLen)
+uLong ZEXPORT compressBound(sourceLen)
    uLong sourceLen;
 {
    return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
@@ -1,5 +1,5 @@
 /* deflate.c -- compress data using the deflation algorithm
- * Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler
+ * Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -52,7 +52,7 @@
 #include "deflate.h"

 const char deflate_copyright[] =
-   " deflate 1.2.11 Copyright 1995-2017 Jean-loup Gailly and Mark Adler ";
+   " deflate 1.2.13 Copyright 1995-2022 Jean-loup Gailly and Mark Adler ";
 /*
  If you use the zlib library in a product, an acknowledgment is welcome
  in the documentation of your product. If for some reason you cannot
@@ -87,13 +87,7 @@ local void lm_init        OF((deflate_state *s));
 local void putShortMSB    OF((deflate_state *s, uInt b));
 local void flush_pending  OF((z_streamp strm));
 local unsigned read_buf   OF((z_streamp strm, Bytef *buf, unsigned size));
-#ifdef ASMV
-#  pragma message("Assembler code may have bugs -- use at your own risk")
-      void match_init OF((void)); /* asm code initialization */
-      uInt longest_match  OF((deflate_state *s, IPos cur_match));
-#else
 local uInt longest_match  OF((deflate_state *s, IPos cur_match));
-#endif

 #ifdef ZLIB_DEBUG
 local  void check_match OF((deflate_state *s, IPos start, IPos match,
@@ -160,7 +154,7 @@ local const config configuration_table[10] = {
 *    characters, so that a running hash key can be computed from the previous
 *    key instead of complete recalculation each time.
 */
-#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
+#define UPDATE_HASH(s,h,c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask)


 /* ===========================================================================
@@ -190,8 +184,11 @@ local const config configuration_table[10] = {
 * prev[] will be initialized on the fly.
 */
 #define CLEAR_HASH(s) \
-    s->head[s->hash_size-1] = NIL; \
-    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
+    do { \
+        s->head[s->hash_size - 1] = NIL; \
+        zmemzero((Bytef *)s->head, \
+                 (unsigned)(s->hash_size - 1)*sizeof(*s->head)); \
+    } while (0)

 /* ===========================================================================
 * Slide the hash table when sliding the window down (could be avoided with 32
@@ -252,11 +249,6 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
    int wrap = 1;
    static const char my_version[] = ZLIB_VERSION;

-    ushf *overlay;
-    /* We overlay pending_buf and d_buf+l_buf. This works since the average
-     * output size for (length,distance) codes is <= 24 bits.
-     */
-
    if (version == Z_NULL || version[0] != my_version[0] ||
        stream_size != sizeof(z_stream)) {
        return Z_VERSION_ERROR;
@@ -287,6 +279,8 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,

    if (windowBits < 0) { /* suppress zlib wrapper */
        wrap = 0;
+        if (windowBits < -15)
+            return Z_STREAM_ERROR;
        windowBits = -windowBits;
    }
 #ifdef GZIP
@@ -316,7 +310,7 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
    s->hash_bits = (uInt)memLevel + 7;
    s->hash_size = 1 << s->hash_bits;
    s->hash_mask = s->hash_size - 1;
-    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
+    s->hash_shift =  ((s->hash_bits + MIN_MATCH-1) / MIN_MATCH);

    s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
    s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
@@ -326,9 +320,47 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,

    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */

-    overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
-    s->pending_buf = (uchf *) overlay;
-    s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
+    /* We overlay pending_buf and sym_buf. This works since the average size
+     * for length/distance pairs over any compressed block is assured to be 31
+     * bits or less.
+     *
+     * Analysis: The longest fixed codes are a length code of 8 bits plus 5
+     * extra bits, for lengths 131 to 257. The longest fixed distance codes are
+     * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest
+     * possible fixed-codes length/distance pair is then 31 bits total.
+     *
+     * sym_buf starts one-fourth of the way into pending_buf. So there are
+     * three bytes in sym_buf for every four bytes in pending_buf. Each symbol
+     * in sym_buf is three bytes -- two for the distance and one for the
+     * literal/length. As each symbol is consumed, the pointer to the next
+     * sym_buf value to read moves forward three bytes. From that symbol, up to
+     * 31 bits are written to pending_buf. The closest the written pending_buf
+     * bits gets to the next sym_buf symbol to read is just before the last
+     * code is written. At that time, 31*(n - 2) bits have been written, just
+     * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at
+     * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1
+     * symbols are written.) The closest the writing gets to what is unread is
+     * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and
+     * can range from 128 to 32768.
+     *
+     * Therefore, at a minimum, there are 142 bits of space between what is
+     * written and what is read in the overlain buffers, so the symbols cannot
+     * be overwritten by the compressed data. That space is actually 139 bits,
+     * due to the three-bit fixed-code block header.
+     *
+     * That covers the case where either Z_FIXED is specified, forcing fixed
+     * codes, or when the use of fixed codes is chosen, because that choice
+     * results in a smaller compressed block than dynamic codes. That latter
+     * condition then assures that the above analysis also covers all dynamic
+     * blocks. A dynamic-code block will only be chosen to be emitted if it has
+     * fewer bits than a fixed-code block would for the same set of symbols.
+     * Therefore its average symbol length is assured to be less than 31. So
+     * the compressed data for a dynamic block also cannot overwrite the
+     * symbols from which it is being constructed.
+     */
+
+    s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4);
+    s->pending_buf_size = (ulg)s->lit_bufsize * 4;

    if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
        s->pending_buf == Z_NULL) {
@@ -337,8 +369,12 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
        deflateEnd (strm);
        return Z_MEM_ERROR;
    }
-    s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
-    s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
+    s->sym_buf = s->pending_buf + s->lit_bufsize;
+    s->sym_end = (s->lit_bufsize - 1) * 3;
+    /* We avoid equality with lit_bufsize*3 because of wraparound at 64K
+     * on 16 bit machines and because stored blocks are restricted to
+     * 64K-1 bytes.
+     */

    s->level = level;
    s->strategy = strategy;
@@ -350,7 +386,7 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
 /* =========================================================================
 * Check for a valid deflate stream state. Return 0 if ok, 1 if not.
 */
-local int deflateStateCheck (strm)
+local int deflateStateCheck(strm)
    z_streamp strm;
 {
    deflate_state *s;
@@ -373,7 +409,7 @@ local int deflateStateCheck (strm)
 }

 /* ========================================================================= */
-int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
+int ZEXPORT deflateSetDictionary(strm, dictionary, dictLength)
    z_streamp strm;
    const Bytef *dictionary;
    uInt  dictLength;
@@ -442,7 +478,7 @@ int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
 }

 /* ========================================================================= */
-int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
+int ZEXPORT deflateGetDictionary(strm, dictionary, dictLength)
    z_streamp strm;
    Bytef *dictionary;
    uInt  *dictLength;
@@ -464,7 +500,7 @@ int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
 }

 /* ========================================================================= */
-int ZEXPORT deflateResetKeep (strm)
+int ZEXPORT deflateResetKeep(strm)
    z_streamp strm;
 {
    deflate_state *s;
@@ -488,13 +524,13 @@ int ZEXPORT deflateResetKeep (strm)
 #ifdef GZIP
        s->wrap == 2 ? GZIP_STATE :
 #endif
-        s->wrap ? INIT_STATE : BUSY_STATE;
+        INIT_STATE;
    strm->adler =
 #ifdef GZIP
        s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
 #endif
        adler32(0L, Z_NULL, 0);
-    s->last_flush = Z_NO_FLUSH;
+    s->last_flush = -2;

    _tr_init(s);

@@ -502,7 +538,7 @@ int ZEXPORT deflateResetKeep (strm)
 }

 /* ========================================================================= */
-int ZEXPORT deflateReset (strm)
+int ZEXPORT deflateReset(strm)
    z_streamp strm;
 {
    int ret;
@@ -514,7 +550,7 @@ int ZEXPORT deflateReset (strm)
 }

 /* ========================================================================= */
-int ZEXPORT deflateSetHeader (strm, head)
+int ZEXPORT deflateSetHeader(strm, head)
    z_streamp strm;
    gz_headerp head;
 {
@@ -525,7 +561,7 @@ int ZEXPORT deflateSetHeader (strm, head)
 }

 /* ========================================================================= */
-int ZEXPORT deflatePending (strm, pending, bits)
+int ZEXPORT deflatePending(strm, pending, bits)
    unsigned *pending;
    int *bits;
    z_streamp strm;
@@ -539,7 +575,7 @@ int ZEXPORT deflatePending (strm, pending, bits)
 }

 /* ========================================================================= */
-int ZEXPORT deflatePrime (strm, bits, value)
+int ZEXPORT deflatePrime(strm, bits, value)
    z_streamp strm;
    int bits;
    int value;
@@ -549,7 +585,8 @@ int ZEXPORT deflatePrime (strm, bits, value)

    if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
    s = strm->state;
-    if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
+    if (bits < 0 || bits > 16 ||
+        s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3))
        return Z_BUF_ERROR;
    do {
        put = Buf_size - s->bi_valid;
@@ -587,12 +624,12 @@ int ZEXPORT deflateParams(strm, level, strategy)
    func = configuration_table[s->level].func;

    if ((strategy != s->strategy || func != configuration_table[level].func) &&
-        s->high_water) {
+        s->last_flush != -2) {
        /* Flush the last buffer: */
        int err = deflate(strm, Z_BLOCK);
        if (err == Z_STREAM_ERROR)
            return err;
-        if (strm->avail_out == 0)
+        if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead)
            return Z_BUF_ERROR;
    }
    if (s->level != level) {
@@ -633,36 +670,50 @@ int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
 }

 /* =========================================================================
- * For the default windowBits of 15 and memLevel of 8, this function returns
- * a close to exact, as well as small, upper bound on the compressed size.
- * They are coded as constants here for a reason--if the #define's are
- * changed, then this function needs to be changed as well.  The return
- * value for 15 and 8 only works for those exact settings.
+ * For the default windowBits of 15 and memLevel of 8, this function returns a
+ * close to exact, as well as small, upper bound on the compressed size. This
+ * is an expansion of ~0.03%, plus a small constant.
 *
- * For any setting other than those defaults for windowBits and memLevel,
- * the value returned is a conservative worst case for the maximum expansion
- * resulting from using fixed blocks instead of stored blocks, which deflate
- * can emit on compressed data for some combinations of the parameters.
+ * For any setting other than those defaults for windowBits and memLevel, one
+ * of two worst case bounds is returned. This is at most an expansion of ~4% or
+ * ~13%, plus a small constant.
 *
- * This function could be more sophisticated to provide closer upper bounds for
- * every combination of windowBits and memLevel.  But even the conservative
- * upper bound of about 14% expansion does not seem onerous for output buffer
- * allocation.
+ * Both the 0.03% and 4% derive from the overhead of stored blocks. The first
+ * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second
+ * is for stored blocks of 127 bytes (the worst case memLevel == 1). The
+ * expansion results from five bytes of header for each stored block.
+ *
+ * The larger expansion of 13% results from a window size less than or equal to
+ * the symbols buffer size (windowBits <= memLevel + 7). In that case some of
+ * the data being compressed may have slid out of the sliding window, impeding
+ * a stored block from being emitted. Then the only choice is a fixed or
+ * dynamic block, where a fixed block limits the maximum expansion to 9 bits
+ * per 8-bit byte, plus 10 bits for every block. The smallest block size for
+ * which this can occur is 255 (memLevel == 2).
+ *
+ * Shifts are used to approximate divisions, for speed.
 */
 uLong ZEXPORT deflateBound(strm, sourceLen)
    z_streamp strm;
    uLong sourceLen;
 {
    deflate_state *s;
-    uLong complen, wraplen;
+    uLong fixedlen, storelen, wraplen;

-    /* conservative upper bound for compressed data */
-    complen = sourceLen +
-              ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
+    /* upper bound for fixed blocks with 9-bit literals and length 255
+       (memLevel == 2, which is the lowest that may not use stored blocks) --
+       ~13% overhead plus a small constant */
+    fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) +
+               (sourceLen >> 9) + 4;

-    /* if can't get parameters, return conservative bound plus zlib wrapper */
+    /* upper bound for stored blocks with length 127 (memLevel == 1) --
+       ~4% overhead plus a small constant */
+    storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) +
+               (sourceLen >> 11) + 7;
+
+    /* if can't get parameters, return larger bound plus a zlib wrapper */
    if (deflateStateCheck(strm))
-        return complen + 6;
+        return (fixedlen > storelen ? fixedlen : storelen) + 6;

    /* compute wrapper length */
    s = strm->state;
@@ -699,11 +750,12 @@ uLong ZEXPORT deflateBound(strm, sourceLen)
        wraplen = 6;
    }

-    /* if not default parameters, return conservative bound */
+    /* if not default parameters, return one of the conservative bounds */
    if (s->w_bits != 15 || s->hash_bits != 8 + 7)
-        return complen + wraplen;
+        return (s->w_bits <= s->hash_bits ? fixedlen : storelen) + wraplen;

-    /* default settings: return tight bound for that case */
+    /* default settings: return tight bound for that case -- ~0.03% overhead
+       plus a small constant */
    return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
           (sourceLen >> 25) + 13 - 6 + wraplen;
 }
@@ -713,7 +765,7 @@ uLong ZEXPORT deflateBound(strm, sourceLen)
 * IN assertion: the stream state is correct and there is enough room in
 * pending_buf.
 */
-local void putShortMSB (s, b)
+local void putShortMSB(s, b)
    deflate_state *s;
    uInt b;
 {
@@ -760,7 +812,7 @@ local void flush_pending(strm)
    } while (0)

 /* ========================================================================= */
-int ZEXPORT deflate (strm, flush)
+int ZEXPORT deflate(strm, flush)
    z_streamp strm;
    int flush;
 {
@@ -811,9 +863,11 @@ int ZEXPORT deflate (strm, flush)
    }

    /* Write the header */
+    if (s->status == INIT_STATE && s->wrap == 0)
+        s->status = BUSY_STATE;
    if (s->status == INIT_STATE) {
        /* zlib header */
-        uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
+        uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8;
        uInt level_flags;

        if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
@@ -1073,7 +1127,7 @@ int ZEXPORT deflate (strm, flush)
 }

 /* ========================================================================= */
-int ZEXPORT deflateEnd (strm)
+int ZEXPORT deflateEnd(strm)
    z_streamp strm;
 {
    int status;
@@ -1099,7 +1153,7 @@ int ZEXPORT deflateEnd (strm)
 * To simplify the source, this is not supported for 16-bit MSDOS (which
 * doesn't have enough memory anyway to duplicate compression states).
 */
-int ZEXPORT deflateCopy (dest, source)
+int ZEXPORT deflateCopy(dest, source)
    z_streamp dest;
    z_streamp source;
 {
@@ -1108,7 +1162,6 @@ int ZEXPORT deflateCopy (dest, source)
 #else
    deflate_state *ds;
    deflate_state *ss;
-    ushf *overlay;


    if (deflateStateCheck(source) || dest == Z_NULL) {
@@ -1128,8 +1181,7 @@ int ZEXPORT deflateCopy (dest, source)
    ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
    ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
    ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
-    overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
-    ds->pending_buf = (uchf *) overlay;
+    ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4);

    if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
        ds->pending_buf == Z_NULL) {
@@ -1143,8 +1195,7 @@ int ZEXPORT deflateCopy (dest, source)
    zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);

    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
-    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
-    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
+    ds->sym_buf = ds->pending_buf + ds->lit_bufsize;

    ds->l_desc.dyn_tree = ds->dyn_ltree;
    ds->d_desc.dyn_tree = ds->dyn_dtree;
@@ -1191,7 +1242,7 @@ local unsigned read_buf(strm, buf, size)
 /* ===========================================================================
 * Initialize the "longest match" routines for a new zlib stream
 */
-local void lm_init (s)
+local void lm_init(s)
    deflate_state *s;
 {
    s->window_size = (ulg)2L*s->w_size;
@@ -1212,11 +1263,6 @@ local void lm_init (s)
    s->match_length = s->prev_length = MIN_MATCH-1;
    s->match_available = 0;
    s->ins_h = 0;
-#ifndef FASTEST
-#ifdef ASMV
-    match_init(); /* initialize the asm code */
-#endif
-#endif
 }

 #ifndef FASTEST
@@ -1229,10 +1275,6 @@ local void lm_init (s)
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 * OUT assertion: the match length is not greater than s->lookahead.
 */
-#ifndef ASMV
-/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
- * match.S. The code will be functionally equivalent.
- */
 local uInt longest_match(s, cur_match)
    deflate_state *s;
    IPos cur_match;                             /* current match */
@@ -1257,10 +1299,10 @@ local uInt longest_match(s, cur_match)
     */
    register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
    register ush scan_start = *(ushf*)scan;
-    register ush scan_end   = *(ushf*)(scan+best_len-1);
+    register ush scan_end   = *(ushf*)(scan + best_len - 1);
 #else
    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
-    register Byte scan_end1  = scan[best_len-1];
+    register Byte scan_end1  = scan[best_len - 1];
    register Byte scan_end   = scan[best_len];
 #endif

@@ -1278,7 +1320,8 @@ local uInt longest_match(s, cur_match)
     */
    if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;

-    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
+    Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
+           "need lookahead");

    do {
        Assert(cur_match < s->strstart, "no future");
@@ -1296,43 +1339,44 @@ local uInt longest_match(s, cur_match)
        /* This code assumes sizeof(unsigned short) == 2. Do not use
         * UNALIGNED_OK if your compiler uses a different size.
         */
-        if (*(ushf*)(match+best_len-1) != scan_end ||
+        if (*(ushf*)(match + best_len - 1) != scan_end ||
            *(ushf*)match != scan_start) continue;

        /* It is not necessary to compare scan[2] and match[2] since they are
         * always equal when the other bytes match, given that the hash keys
         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
-         * strstart+3, +5, ... up to strstart+257. We check for insufficient
+         * strstart + 3, + 5, up to strstart + 257. We check for insufficient
         * lookahead only every 4th comparison; the 128th check will be made
-         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
+         * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is
         * necessary to put more guard bytes at the end of the window, or
         * to check more often for insufficient lookahead.
         */
        Assert(scan[2] == match[2], "scan[2]?");
        scan++, match++;
        do {
-        } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
-                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
-                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
-                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
+        } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) &&
+                 *(ushf*)(scan += 2) == *(ushf*)(match += 2) &&
+                 *(ushf*)(scan += 2) == *(ushf*)(match += 2) &&
+                 *(ushf*)(scan += 2) == *(ushf*)(match += 2) &&
                 scan < strend);
        /* The funny "do {}" generates better code on most compilers */

-        /* Here, scan <= window+strstart+257 */
-        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
+        /* Here, scan <= window + strstart + 257 */
+        Assert(scan <= s->window + (unsigned)(s->window_size - 1),
+               "wild scan");
        if (*scan == *match) scan++;

-        len = (MAX_MATCH - 1) - (int)(strend-scan);
+        len = (MAX_MATCH - 1) - (int)(strend - scan);
        scan = strend - (MAX_MATCH-1);

 #else /* UNALIGNED_OK */

-        if (match[best_len]   != scan_end  ||
-            match[best_len-1] != scan_end1 ||
-            *match            != *scan     ||
-            *++match          != scan[1])      continue;
+        if (match[best_len]     != scan_end  ||
+            match[best_len - 1] != scan_end1 ||
+            *match              != *scan     ||
+            *++match            != scan[1])      continue;

-        /* The check at best_len-1 can be removed because it will be made
+        /* The check at best_len - 1 can be removed because it will be made
         * again later. (This heuristic is not always a win.)
         * It is not necessary to compare scan[2] and match[2] since they
         * are always equal when the other bytes match, given that
@@ -1342,7 +1386,7 @@ local uInt longest_match(s, cur_match)
        Assert(*scan == *match, "match[2]?");

        /* We check for insufficient lookahead only every 8th comparison;
-         * the 256th check will be made at strstart+258.
+         * the 256th check will be made at strstart + 258.
         */
        do {
        } while (*++scan == *++match && *++scan == *++match &&
@@ -1351,7 +1395,8 @@ local uInt longest_match(s, cur_match)
                 *++scan == *++match && *++scan == *++match &&
                 scan < strend);

-        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
+        Assert(scan <= s->window + (unsigned)(s->window_size - 1),
+               "wild scan");

        len = MAX_MATCH - (int)(strend - scan);
        scan = strend - MAX_MATCH;
@@ -1363,9 +1408,9 @@ local uInt longest_match(s, cur_match)
            best_len = len;
            if (len >= nice_match) break;
 #ifdef UNALIGNED_OK
-            scan_end = *(ushf*)(scan+best_len-1);
+            scan_end = *(ushf*)(scan + best_len - 1);
 #else
-            scan_end1  = scan[best_len-1];
+            scan_end1  = scan[best_len - 1];
            scan_end   = scan[best_len];
 #endif
        }
@@ -1375,7 +1420,6 @@ local uInt longest_match(s, cur_match)
    if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
    return s->lookahead;
 }
-#endif /* ASMV */

 #else /* FASTEST */

@@ -1396,7 +1440,8 @@ local uInt longest_match(s, cur_match)
     */
    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");

-    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
+    Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
+           "need lookahead");

    Assert(cur_match < s->strstart, "no future");

@@ -1406,7 +1451,7 @@ local uInt longest_match(s, cur_match)
     */
    if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;

-    /* The check at best_len-1 can be removed because it will be made
+    /* The check at best_len - 1 can be removed because it will be made
     * again later. (This heuristic is not always a win.)
     * It is not necessary to compare scan[2] and match[2] since they
     * are always equal when the other bytes match, given that
@@ -1416,7 +1461,7 @@ local uInt longest_match(s, cur_match)
    Assert(*scan == *match, "match[2]?");

    /* We check for insufficient lookahead only every 8th comparison;
-     * the 256th check will be made at strstart+258.
+     * the 256th check will be made at strstart + 258.
     */
    do {
    } while (*++scan == *++match && *++scan == *++match &&
@@ -1425,7 +1470,7 @@ local uInt longest_match(s, cur_match)
             *++scan == *++match && *++scan == *++match &&
             scan < strend);

-    Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
+    Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan");

    len = MAX_MATCH - (int)(strend - scan);

@@ -1461,7 +1506,7 @@ local void check_match(s, start, match, length)
        z_error("invalid match");
    }
    if (z_verbose > 1) {
-        fprintf(stderr,"\\[%d,%d]", start-match, length);
+        fprintf(stderr,"\\[%d,%d]", start - match, length);
        do { putc(s->window[start++], stderr); } while (--length != 0);
    }
 }
@@ -1507,12 +1552,14 @@ local void fill_window(s)
        /* If the window is almost full and there is insufficient lookahead,
         * move the upper half to the lower one to make room in the upper half.
         */
-        if (s->strstart >= wsize+MAX_DIST(s)) {
+        if (s->strstart >= wsize + MAX_DIST(s)) {

-            zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more);
+            zmemcpy(s->window, s->window + wsize, (unsigned)wsize - more);
            s->match_start -= wsize;
            s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
            s->block_start -= (long) wsize;
+            if (s->insert > s->strstart)
+                s->insert = s->strstart;
            slide_hash(s);
            more += wsize;
        }
@@ -1638,7 +1685,7 @@ local void fill_window(s)
 *
 * deflate_stored() is written to minimize the number of times an input byte is
 * copied. It is most efficient with large input and output buffers, which
- * maximizes the opportunites to have a single copy from next_in to next_out.
+ * maximizes the opportunities to have a single copy from next_in to next_out.
 */
 local block_state deflate_stored(s, flush)
    deflate_state *s;
@@ -1742,6 +1789,7 @@ local block_state deflate_stored(s, flush)
            s->matches = 2;         /* clear hash */
            zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
            s->strstart = s->w_size;
+            s->insert = s->strstart;
        }
        else {
            if (s->window_size - s->strstart <= used) {
@@ -1750,12 +1798,14 @@ local block_state deflate_stored(s, flush)
                zmemcpy(s->window, s->window + s->w_size, s->strstart);
                if (s->matches < 2)
                    s->matches++;   /* add a pending slide_hash() */
+                if (s->insert > s->strstart)
+                    s->insert = s->strstart;
            }
            zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);
            s->strstart += used;
+            s->insert += MIN(used, s->w_size - s->insert);
        }
        s->block_start = s->strstart;
-        s->insert += MIN(used, s->w_size - s->insert);
    }
    if (s->high_water < s->strstart)
        s->high_water = s->strstart;
@@ -1770,7 +1820,7 @@ local block_state deflate_stored(s, flush)
        return block_done;

    /* Fill the window with any remaining input. */
-    have = s->window_size - s->strstart - 1;
+    have = s->window_size - s->strstart;
    if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) {
        /* Slide the window down. */
        s->block_start -= s->w_size;
@@ -1779,12 +1829,15 @@ local block_state deflate_stored(s, flush)
        if (s->matches < 2)
            s->matches++;           /* add a pending slide_hash() */
        have += s->w_size;          /* more space now */
+        if (s->insert > s->strstart)
+            s->insert = s->strstart;
    }
    if (have > s->strm->avail_in)
        have = s->strm->avail_in;
    if (have) {
        read_buf(s->strm, s->window + s->strstart, have);
        s->strstart += have;
+        s->insert += MIN(have, s->w_size - s->insert);
    }
    if (s->high_water < s->strstart)
        s->high_water = s->strstart;
@@ -1842,7 +1895,7 @@ local block_state deflate_fast(s, flush)
            if (s->lookahead == 0) break; /* flush the current block */
        }

-        /* Insert the string window[strstart .. strstart+2] in the
+        /* Insert the string window[strstart .. strstart + 2] in the
         * dictionary, and set hash_head to the head of the hash chain:
         */
        hash_head = NIL;
@@ -1890,7 +1943,7 @@ local block_state deflate_fast(s, flush)
                s->strstart += s->match_length;
                s->match_length = 0;
                s->ins_h = s->window[s->strstart];
-                UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
+                UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]);
 #if MIN_MATCH != 3
                Call UPDATE_HASH() MIN_MATCH-3 more times
 #endif
@@ -1901,7 +1954,7 @@ local block_state deflate_fast(s, flush)
        } else {
            /* No match, output a literal byte */
            Tracevv((stderr,"%c", s->window[s->strstart]));
-            _tr_tally_lit (s, s->window[s->strstart], bflush);
+            _tr_tally_lit(s, s->window[s->strstart], bflush);
            s->lookahead--;
            s->strstart++;
        }
@@ -1912,7 +1965,7 @@ local block_state deflate_fast(s, flush)
        FLUSH_BLOCK(s, 1);
        return finish_done;
    }
-    if (s->last_lit)
+    if (s->sym_next)
        FLUSH_BLOCK(s, 0);
    return block_done;
 }
@@ -1945,7 +1998,7 @@ local block_state deflate_slow(s, flush)
            if (s->lookahead == 0) break; /* flush the current block */
        }

-        /* Insert the string window[strstart .. strstart+2] in the
+        /* Insert the string window[strstart .. strstart + 2] in the
         * dictionary, and set hash_head to the head of the hash chain:
         */
        hash_head = NIL;
@@ -1987,17 +2040,17 @@ local block_state deflate_slow(s, flush)
            uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
            /* Do not insert strings in hash table beyond this. */

-            check_match(s, s->strstart-1, s->prev_match, s->prev_length);
+            check_match(s, s->strstart - 1, s->prev_match, s->prev_length);

-            _tr_tally_dist(s, s->strstart -1 - s->prev_match,
+            _tr_tally_dist(s, s->strstart - 1 - s->prev_match,
                           s->prev_length - MIN_MATCH, bflush);

            /* Insert in hash table all strings up to the end of the match.
-             * strstart-1 and strstart are already inserted. If there is not
+             * strstart - 1 and strstart are already inserted. If there is not
             * enough lookahead, the last two strings are not inserted in
             * the hash table.
             */
-            s->lookahead -= s->prev_length-1;
+            s->lookahead -= s->prev_length - 1;
            s->prev_length -= 2;
            do {
                if (++s->strstart <= max_insert) {
@@ -2015,8 +2068,8 @@ local block_state deflate_slow(s, flush)
             * single literal. If there was a match but the current match
             * is longer, truncate the previous match to a single literal.
             */
-            Tracevv((stderr,"%c", s->window[s->strstart-1]));
-            _tr_tally_lit(s, s->window[s->strstart-1], bflush);
+            Tracevv((stderr,"%c", s->window[s->strstart - 1]));
+            _tr_tally_lit(s, s->window[s->strstart - 1], bflush);
            if (bflush) {
                FLUSH_BLOCK_ONLY(s, 0);
            }
@@ -2034,8 +2087,8 @@ local block_state deflate_slow(s, flush)
    }
    Assert (flush != Z_NO_FLUSH, "no flush?");
    if (s->match_available) {
-        Tracevv((stderr,"%c", s->window[s->strstart-1]));
-        _tr_tally_lit(s, s->window[s->strstart-1], bflush);
+        Tracevv((stderr,"%c", s->window[s->strstart - 1]));
+        _tr_tally_lit(s, s->window[s->strstart - 1], bflush);
        s->match_available = 0;
    }
    s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
@@ -2043,7 +2096,7 @@ local block_state deflate_slow(s, flush)
        FLUSH_BLOCK(s, 1);
        return finish_done;
    }
-    if (s->last_lit)
+    if (s->sym_next)
        FLUSH_BLOCK(s, 0);
    return block_done;
 }
@@ -2092,7 +2145,8 @@ local block_state deflate_rle(s, flush)
                if (s->match_length > s->lookahead)
                    s->match_length = s->lookahead;
            }
-            Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
+            Assert(scan <= s->window + (uInt)(s->window_size - 1),
+                   "wild scan");
        }

        /* Emit match if have run of MIN_MATCH or longer, else emit literal */
@@ -2107,7 +2161,7 @@ local block_state deflate_rle(s, flush)
        } else {
            /* No match, output a literal byte */
            Tracevv((stderr,"%c", s->window[s->strstart]));
-            _tr_tally_lit (s, s->window[s->strstart], bflush);
+            _tr_tally_lit(s, s->window[s->strstart], bflush);
            s->lookahead--;
            s->strstart++;
        }
@@ -2118,7 +2172,7 @@ local block_state deflate_rle(s, flush)
        FLUSH_BLOCK(s, 1);
        return finish_done;
    }
-    if (s->last_lit)
+    if (s->sym_next)
        FLUSH_BLOCK(s, 0);
    return block_done;
 }
@@ -2147,7 +2201,7 @@ local block_state deflate_huff(s, flush)
        /* Output a literal byte */
        s->match_length = 0;
        Tracevv((stderr,"%c", s->window[s->strstart]));
-        _tr_tally_lit (s, s->window[s->strstart], bflush);
+        _tr_tally_lit(s, s->window[s->strstart], bflush);
        s->lookahead--;
        s->strstart++;
        if (bflush) FLUSH_BLOCK(s, 0);
@@ -2157,7 +2211,7 @@ local block_state deflate_huff(s, flush)
        FLUSH_BLOCK(s, 1);
        return finish_done;
    }
-    if (s->last_lit)
+    if (s->sym_next)
        FLUSH_BLOCK(s, 0);
    return block_done;
 }
@@ -1,5 +1,5 @@
 /* deflate.h -- internal compression state
- * Copyright (C) 1995-2016 Jean-loup Gailly
+ * Copyright (C) 1995-2018 Jean-loup Gailly
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -217,7 +217,7 @@ typedef struct internal_state {
    /* Depth of each subtree used as tie breaker for trees of equal frequency
     */

-    uchf *l_buf;          /* buffer for literals or lengths */
+    uchf *sym_buf;        /* buffer for distances and literals/lengths */

    uInt  lit_bufsize;
    /* Size of match buffer for literals/lengths.  There are 4 reasons for
@@ -239,13 +239,8 @@ typedef struct internal_state {
     *   - I can't count above 4
     */

-    uInt last_lit;      /* running index in l_buf */
-
-    ushf *d_buf;
-    /* Buffer for distances. To simplify the code, d_buf and l_buf have
-     * the same number of elements. To use different lengths, an extra flag
-     * array would be necessary.
-     */
+    uInt sym_next;      /* running index in sym_buf */
+    uInt sym_end;       /* symbol table full when sym_next reaches this */

    ulg opt_len;        /* bit length of current block with optimal trees */
    ulg static_len;     /* bit length of current block with static trees */
@@ -325,20 +320,22 @@ void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf,

 # define _tr_tally_lit(s, c, flush) \
  { uch cc = (c); \
-    s->d_buf[s->last_lit] = 0; \
-    s->l_buf[s->last_lit++] = cc; \
+    s->sym_buf[s->sym_next++] = 0; \
+    s->sym_buf[s->sym_next++] = 0; \
+    s->sym_buf[s->sym_next++] = cc; \
    s->dyn_ltree[cc].Freq++; \
-    flush = (s->last_lit == s->lit_bufsize-1); \
+    flush = (s->sym_next == s->sym_end); \
   }
 # define _tr_tally_dist(s, distance, length, flush) \
  { uch len = (uch)(length); \
    ush dist = (ush)(distance); \
-    s->d_buf[s->last_lit] = dist; \
-    s->l_buf[s->last_lit++] = len; \
+    s->sym_buf[s->sym_next++] = (uch)dist; \
+    s->sym_buf[s->sym_next++] = (uch)(dist >> 8); \
+    s->sym_buf[s->sym_next++] = len; \
    dist--; \
    s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
    s->dyn_dtree[d_code(dist)].Freq++; \
-    flush = (s->last_lit == s->lit_bufsize-1); \
+    flush = (s->sym_next == s->sym_end); \
  }
 #else
 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
@@ -1,5 +1,5 @@
 /* gzguts.h -- zlib internal header definitions for gz* operations
- * Copyright (C) 2004, 2005, 2010, 2011, 2012, 2013, 2016 Mark Adler
+ * Copyright (C) 2004-2019 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -39,7 +39,7 @@
 #  include <io.h>
 #endif

-#if defined(_WIN32) || defined(__CYGWIN__)
+#if defined(_WIN32)
 #  define WIDECHAR
 #endif

@@ -190,6 +190,7 @@ typedef struct {
        /* just for writing */
    int level;              /* compression level */
    int strategy;           /* compression strategy */
+    int reset;              /* true if a reset is pending after a Z_FINISH */
        /* seek request */
    z_off64_t skip;         /* amount to skip (already rewound if backwards) */
    int seek;               /* true if seek request pending */
@@ -1,11 +1,11 @@
 /* gzlib.c -- zlib functions common to reading and writing gzip files
- * Copyright (C) 2004-2017 Mark Adler
+ * Copyright (C) 2004-2019 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

 #include "gzguts.h"

-#if defined(_WIN32) && !defined(__BORLANDC__) && !defined(__MINGW32__)
+#if defined(_WIN32) && !defined(__BORLANDC__)
 #  define LSEEK _lseeki64
 #else
 #if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
@@ -30,7 +30,7 @@ local gzFile gz_open OF((const void *, int, const char *));

   The gz_strwinerror function does not change the current setting of
   GetLastError. */
-char ZLIB_INTERNAL *gz_strwinerror (error)
+char ZLIB_INTERNAL *gz_strwinerror(error)
     DWORD error;
 {
    static char buf[1024];
@@ -81,6 +81,8 @@ local void gz_reset(state)
        state->past = 0;            /* have not read past end yet */
        state->how = LOOK;          /* look for gzip header */
    }
+    else                            /* for writing ... */
+        state->reset = 0;           /* no deflateReset pending */
    state->seek = 0;                /* no seek request pending */
    gz_error(state, Z_OK, NULL);    /* clear error */
    state->x.pos = 0;               /* no uncompressed data yet */
@@ -397,7 +399,7 @@ z_off64_t ZEXPORT gzseek64(file, offset, whence)
    /* if within raw area while reading, just go there */
    if (state->mode == GZ_READ && state->how == COPY &&
            state->x.pos + offset >= 0) {
-        ret = LSEEK(state->fd, offset - state->x.have, SEEK_CUR);
+        ret = LSEEK(state->fd, offset - (z_off64_t)state->x.have, SEEK_CUR);
        if (ret == -1)
            return -1;
        state->x.have = 0;
@@ -1,5 +1,5 @@
 /* gzread.c -- zlib functions for reading gzip files
- * Copyright (C) 2004, 2005, 2010, 2011, 2012, 2013, 2016 Mark Adler
+ * Copyright (C) 2004-2017 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -157,11 +157,9 @@ local int gz_look(state)
       the output buffer is larger than the input buffer, which also assures
       space for gzungetc() */
    state->x.next = state->out;
-    if (strm->avail_in) {
-        memcpy(state->x.next, strm->next_in, strm->avail_in);
-        state->x.have = strm->avail_in;
-        strm->avail_in = 0;
-    }
+    memcpy(state->x.next, strm->next_in, strm->avail_in);
+    state->x.have = strm->avail_in;
+    strm->avail_in = 0;
    state->how = COPY;
    state->direct = 1;
    return 0;
@@ -314,9 +312,9 @@ local z_size_t gz_read(state, buf, len)
    got = 0;
    do {
        /* set n to the maximum amount of len that fits in an unsigned int */
-        n = -1;
+        n = (unsigned)-1;
        if (n > len)
-            n = (int)len;
+            n = (unsigned)len;

        /* first just try copying data from the output buffer */
        if (state->x.have) {
@@ -397,7 +395,7 @@ int ZEXPORT gzread(file, buf, len)
    }

    /* read len or fewer bytes to buf */
-    len = (int)gz_read(state, buf, len);
+    len = (unsigned)gz_read(state, buf, len);

    /* check for an error */
    if (len == 0 && state->err != Z_OK && state->err != Z_BUF_ERROR)
@@ -447,7 +445,6 @@ z_size_t ZEXPORT gzfread(buf, size, nitems, file)
 int ZEXPORT gzgetc(file)
    gzFile file;
 {
-    int ret;
    unsigned char buf[1];
    gz_statep state;

@@ -469,8 +466,7 @@ int ZEXPORT gzgetc(file)
    }

    /* nothing there -- try gz_read() */
-    ret = (int)gz_read(state, buf, 1);
-    return ret < 1 ? -1 : buf[0];
+    return gz_read(state, buf, 1) < 1 ? -1 : buf[0];
 }

 int ZEXPORT gzgetc_(file)
@@ -1,5 +1,5 @@
 /* gzwrite.c -- zlib functions for writing gzip files
- * Copyright (C) 2004-2017 Mark Adler
+ * Copyright (C) 2004-2019 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -97,6 +97,15 @@ local int gz_comp(state, flush)
        return 0;
    }

+    /* check for a pending reset */
+    if (state->reset) {
+        /* don't start a new gzip member unless there is data to write */
+        if (strm->avail_in == 0)
+            return 0;
+        deflateReset(strm);
+        state->reset = 0;
+    }
+
    /* run deflate() on provided input until it produces no more output */
    ret = Z_OK;
    do {
@@ -134,7 +143,7 @@ local int gz_comp(state, flush)

    /* if that completed a deflate stream, allow another to start */
    if (flush == Z_FINISH)
-        deflateReset(strm);
+        state->reset = 1;

    /* all done, no errors */
    return 0;
@@ -209,7 +218,7 @@ local z_size_t gz_write(state, buf, len)
                              state->in);
            copy = state->size - have;
            if (copy > len)
-                copy = (int)len;
+                copy = (unsigned)len;
            memcpy(state->in + have, buf, copy);
            state->strm.avail_in += copy;
            state->x.pos += copy;
@@ -229,7 +238,7 @@ local z_size_t gz_write(state, buf, len)
        do {
            unsigned n = (unsigned)-1;
            if (n > len)
-                n = (int)len;
+                n = (unsigned)len;
            state->strm.avail_in = n;
            state->x.pos += n;
            if (gz_comp(state, Z_NO_FLUSH) == -1)
@@ -349,12 +358,11 @@ int ZEXPORT gzputc(file, c)
 }

 /* -- see zlib.h -- */
-int ZEXPORT gzputs(file, str)
+int ZEXPORT gzputs(file, s)
    gzFile file;
-    const char *str;
+    const char *s;
 {
-    int ret;
-    z_size_t len;
+    z_size_t len, put;
    gz_statep state;

    /* get internal structure */
@@ -367,9 +375,13 @@ int ZEXPORT gzputs(file, str)
        return -1;

    /* write string */
-    len = strlen(str);
-    ret = (int)gz_write(state, str, len);
-    return ret == 0 && len != 0 ? -1 : ret;
+    len = strlen(s);
+    if ((int)len < 0 || (unsigned)len != len) {
+        gz_error(state, Z_STREAM_ERROR, "string length does not fit in int");
+        return -1;
+    }
+    put = gz_write(state, s, len);
+    return put < len ? -1 : (int)len;
 }

 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
@@ -441,7 +453,7 @@ int ZEXPORTVA gzvprintf(gzFile file, const char *format, va_list va)
        strm->avail_in = state->size;
        if (gz_comp(state, Z_NO_FLUSH) == -1)
            return state->err;
-        memcpy(state->in, state->in + state->size, left);
+        memmove(state->in, state->in + state->size, left);
        strm->next_in = state->in;
        strm->avail_in = left;
    }
@@ -462,7 +474,7 @@ int ZEXPORTVA gzprintf(gzFile file, const char *format, ...)
 #else /* !STDC && !Z_HAVE_STDARG_H */

 /* -- see zlib.h -- */
-int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
+int ZEXPORTVA gzprintf(file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
                       a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
    gzFile file;
    const char *format;
@@ -540,7 +552,7 @@ int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
        strm->avail_in = state->size;
        if (gz_comp(state, Z_NO_FLUSH) == -1)
            return state->err;
-        memcpy(state->in, state->in + state->size, left);
+        memmove(state->in, state->in + state->size, left);
        strm->next_in = state->in;
        strm->avail_in = left;
    }
@@ -1,5 +1,5 @@
 /* infback.c -- inflate using a call-back interface
- * Copyright (C) 1995-2016 Mark Adler
+ * Copyright (C) 1995-2022 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -66,6 +66,7 @@ int stream_size;
    state->window = window;
    state->wnext = 0;
    state->whave = 0;
+    state->sane = 1;
    return Z_OK;
 }

@@ -477,6 +478,7 @@ void FAR *out_desc;
            }
            Tracev((stderr, "inflate:       codes ok\n"));
            state->mode = LEN;
+                /* fallthrough */

        case LEN:
            /* use inflate_fast() if we have enough input and output */
@@ -604,25 +606,27 @@ void FAR *out_desc;
            break;

        case DONE:
-            /* inflate stream terminated properly -- write leftover output */
+            /* inflate stream terminated properly */
            ret = Z_STREAM_END;
-            if (left < state->wsize) {
-                if (out(out_desc, state->window, state->wsize - left))
-                    ret = Z_BUF_ERROR;
-            }
            goto inf_leave;

        case BAD:
            ret = Z_DATA_ERROR;
            goto inf_leave;

-        default:                /* can't happen, but makes compilers happy */
+        default:
+            /* can't happen, but makes compilers happy */
            ret = Z_STREAM_ERROR;
            goto inf_leave;
        }

-    /* Return unused input */
+    /* Write leftover output and return unused input */
  inf_leave:
+    if (left < state->wsize) {
+        if (out(out_desc, state->window, state->wsize - left) &&
+            ret == Z_STREAM_END)
+            ret = Z_BUF_ERROR;
+    }
    strm->next_in = next;
    strm->avail_in = have;
    return ret;
@@ -70,7 +70,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
    code const FAR *dcode;      /* local strm->distcode */
    unsigned lmask;             /* mask for first level of length codes */
    unsigned dmask;             /* mask for first level of distance codes */
-    code here;                  /* retrieved table entry */
+    code const *here;           /* retrieved table entry */
    unsigned op;                /* code bits, operation, extra bits, or */
                                /*  window position, window bytes to copy */
    unsigned len;               /* match length, unused bytes */
@@ -107,20 +107,20 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
            hold += (unsigned long)(*in++) << bits;
            bits += 8;
        }
-        here = lcode[hold & lmask];
+        here = lcode + (hold & lmask);
      dolen:
-        op = (unsigned)(here.bits);
+        op = (unsigned)(here->bits);
        hold >>= op;
        bits -= op;
-        op = (unsigned)(here.op);
+        op = (unsigned)(here->op);
        if (op == 0) {                          /* literal */
-            Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
+            Tracevv((stderr, here->val >= 0x20 && here->val < 0x7f ?
                    "inflate:         literal '%c'\n" :
-                    "inflate:         literal 0x%02x\n", here.val));
-            *out++ = (unsigned char)(here.val);
+                    "inflate:         literal 0x%02x\n", here->val));
+            *out++ = (unsigned char)(here->val);
        }
        else if (op & 16) {                     /* length base */
-            len = (unsigned)(here.val);
+            len = (unsigned)(here->val);
            op &= 15;                           /* number of extra bits */
            if (op) {
                if (bits < op) {
@@ -138,14 +138,14 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
                hold += (unsigned long)(*in++) << bits;
                bits += 8;
            }
-            here = dcode[hold & dmask];
+            here = dcode + (hold & dmask);
          dodist:
-            op = (unsigned)(here.bits);
+            op = (unsigned)(here->bits);
            hold >>= op;
            bits -= op;
-            op = (unsigned)(here.op);
+            op = (unsigned)(here->op);
            if (op & 16) {                      /* distance base */
-                dist = (unsigned)(here.val);
+                dist = (unsigned)(here->val);
                op &= 15;                       /* number of extra bits */
                if (bits < op) {
                    hold += (unsigned long)(*in++) << bits;
@@ -264,7 +264,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
                }
            }
            else if ((op & 64) == 0) {          /* 2nd level distance code */
-                here = dcode[here.val + (hold & ((1U << op) - 1))];
+                here = dcode + here->val + (hold & ((1U << op) - 1));
                goto dodist;
            }
            else {
@@ -274,7 +274,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
            }
        }
        else if ((op & 64) == 0) {              /* 2nd level length code */
-            here = lcode[here.val + (hold & ((1U << op) - 1))];
+            here = lcode + here->val + (hold & ((1U << op) - 1));
            goto dolen;
        }
        else if (op & 32) {                     /* end-of-block */
@@ -1,5 +1,5 @@
 /* inflate.c -- zlib decompression
- * Copyright (C) 1995-2016 Mark Adler
+ * Copyright (C) 1995-2022 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -130,6 +130,7 @@ z_streamp strm;
    state->mode = HEAD;
    state->last = 0;
    state->havedict = 0;
+    state->flags = -1;
    state->dmax = 32768U;
    state->head = Z_NULL;
    state->hold = 0;
@@ -167,6 +168,8 @@ int windowBits;

    /* extract wrap request from windowBits parameter */
    if (windowBits < 0) {
+        if (windowBits < -15)
+            return Z_STREAM_ERROR;
        wrap = 0;
        windowBits = -windowBits;
    }
@@ -448,10 +451,10 @@ unsigned copy;

 /* check function to use adler32() for zlib or crc32() for gzip */
 #ifdef GUNZIP
-#  define UPDATE(check, buf, len) \
+#  define UPDATE_CHECK(check, buf, len) \
    (state->flags ? crc32(check, buf, len) : adler32(check, buf, len))
 #else
-#  define UPDATE(check, buf, len) adler32(check, buf, len)
+#  define UPDATE_CHECK(check, buf, len) adler32(check, buf, len)
 #endif

 /* check macros for header crc */
@@ -671,7 +674,6 @@ int flush;
                state->mode = FLAGS;
                break;
            }
-            state->flags = 0;           /* expect zlib header */
            if (state->head != Z_NULL)
                state->head->done = -1;
            if (!(state->wrap & 1) ||   /* check if zlib header allowed */
@@ -698,6 +700,7 @@ int flush;
                break;
            }
            state->dmax = 1U << len;
+            state->flags = 0;               /* indicate zlib header */
            Tracev((stderr, "inflate:   zlib header ok\n"));
            strm->adler = state->check = adler32(0L, Z_NULL, 0);
            state->mode = hold & 0x200 ? DICTID : TYPE;
@@ -723,6 +726,7 @@ int flush;
                CRC2(state->check, hold);
            INITBITS();
            state->mode = TIME;
+                /* fallthrough */
        case TIME:
            NEEDBITS(32);
            if (state->head != Z_NULL)
@@ -731,6 +735,7 @@ int flush;
                CRC4(state->check, hold);
            INITBITS();
            state->mode = OS;
+                /* fallthrough */
        case OS:
            NEEDBITS(16);
            if (state->head != Z_NULL) {
@@ -741,6 +746,7 @@ int flush;
                CRC2(state->check, hold);
            INITBITS();
            state->mode = EXLEN;
+                /* fallthrough */
        case EXLEN:
            if (state->flags & 0x0400) {
                NEEDBITS(16);
@@ -754,14 +760,16 @@ int flush;
            else if (state->head != Z_NULL)
                state->head->extra = Z_NULL;
            state->mode = EXTRA;
+                /* fallthrough */
        case EXTRA:
            if (state->flags & 0x0400) {
                copy = state->length;
                if (copy > have) copy = have;
                if (copy) {
                    if (state->head != Z_NULL &&
-                        state->head->extra != Z_NULL) {
-                        len = state->head->extra_len - state->length;
+                        state->head->extra != Z_NULL &&
+                        (len = state->head->extra_len - state->length) <
+                            state->head->extra_max) {
                        zmemcpy(state->head->extra + len, next,
                                len + copy > state->head->extra_max ?
                                state->head->extra_max - len : copy);
@@ -776,6 +784,7 @@ int flush;
            }
            state->length = 0;
            state->mode = NAME;
+                /* fallthrough */
        case NAME:
            if (state->flags & 0x0800) {
                if (have == 0) goto inf_leave;
@@ -797,6 +806,7 @@ int flush;
                state->head->name = Z_NULL;
            state->length = 0;
            state->mode = COMMENT;
+                /* fallthrough */
        case COMMENT:
            if (state->flags & 0x1000) {
                if (have == 0) goto inf_leave;
@@ -817,6 +827,7 @@ int flush;
            else if (state->head != Z_NULL)
                state->head->comment = Z_NULL;
            state->mode = HCRC;
+                /* fallthrough */
        case HCRC:
            if (state->flags & 0x0200) {
                NEEDBITS(16);
@@ -840,6 +851,7 @@ int flush;
            strm->adler = state->check = ZSWAP32(hold);
            INITBITS();
            state->mode = DICT;
+                /* fallthrough */
        case DICT:
            if (state->havedict == 0) {
                RESTORE();
@@ -847,8 +859,10 @@ int flush;
            }
            strm->adler = state->check = adler32(0L, Z_NULL, 0);
            state->mode = TYPE;
+                /* fallthrough */
        case TYPE:
            if (flush == Z_BLOCK || flush == Z_TREES) goto inf_leave;
+                /* fallthrough */
        case TYPEDO:
            if (state->last) {
                BYTEBITS();
@@ -899,8 +913,10 @@ int flush;
            INITBITS();
            state->mode = COPY_;
            if (flush == Z_TREES) goto inf_leave;
+                /* fallthrough */
        case COPY_:
            state->mode = COPY;
+                /* fallthrough */
        case COPY:
            copy = state->length;
            if (copy) {
@@ -936,6 +952,7 @@ int flush;
            Tracev((stderr, "inflate:       table sizes ok\n"));
            state->have = 0;
            state->mode = LENLENS;
+                /* fallthrough */
        case LENLENS:
            while (state->have < state->ncode) {
                NEEDBITS(3);
@@ -957,6 +974,7 @@ int flush;
            Tracev((stderr, "inflate:       code lengths ok\n"));
            state->have = 0;
            state->mode = CODELENS;
+                /* fallthrough */
        case CODELENS:
            while (state->have < state->nlen + state->ndist) {
                for (;;) {
@@ -1040,8 +1058,10 @@ int flush;
            Tracev((stderr, "inflate:       codes ok\n"));
            state->mode = LEN_;
            if (flush == Z_TREES) goto inf_leave;
+                /* fallthrough */
        case LEN_:
            state->mode = LEN;
+                /* fallthrough */
        case LEN:
            if (have >= 6 && left >= 258) {
                RESTORE();
@@ -1091,6 +1111,7 @@ int flush;
            }
            state->extra = (unsigned)(here.op) & 15;
            state->mode = LENEXT;
+                /* fallthrough */
        case LENEXT:
            if (state->extra) {
                NEEDBITS(state->extra);
@@ -1101,6 +1122,7 @@ int flush;
            Tracevv((stderr, "inflate:         length %u\n", state->length));
            state->was = state->length;
            state->mode = DIST;
+                /* fallthrough */
        case DIST:
            for (;;) {
                here = state->distcode[BITS(state->distbits)];
@@ -1128,6 +1150,7 @@ int flush;
            state->offset = (unsigned)here.val;
            state->extra = (unsigned)(here.op) & 15;
            state->mode = DISTEXT;
+                /* fallthrough */
        case DISTEXT:
            if (state->extra) {
                NEEDBITS(state->extra);
@@ -1144,6 +1167,7 @@ int flush;
 #endif
            Tracevv((stderr, "inflate:         distance %u\n", state->offset));
            state->mode = MATCH;
+                /* fallthrough */
        case MATCH:
            if (left == 0) goto inf_leave;
            copy = out - left;
@@ -1203,7 +1227,7 @@ int flush;
                state->total += out;
                if ((state->wrap & 4) && out)
                    strm->adler = state->check =
-                        UPDATE(state->check, put - out, out);
+                        UPDATE_CHECK(state->check, put - out, out);
                out = left;
                if ((state->wrap & 4) && (
 #ifdef GUNZIP
@@ -1219,10 +1243,11 @@ int flush;
            }
 #ifdef GUNZIP
            state->mode = LENGTH;
+                /* fallthrough */
        case LENGTH:
            if (state->wrap && state->flags) {
                NEEDBITS(32);
-                if (hold != (state->total & 0xffffffffUL)) {
+                if ((state->wrap & 4) && hold != (state->total & 0xffffffff)) {
                    strm->msg = (char *)"incorrect length check";
                    state->mode = BAD;
                    break;
@@ -1232,6 +1257,7 @@ int flush;
            }
 #endif
            state->mode = DONE;
+                /* fallthrough */
        case DONE:
            ret = Z_STREAM_END;
            goto inf_leave;
@@ -1241,6 +1267,7 @@ int flush;
        case MEM:
            return Z_MEM_ERROR;
        case SYNC:
+                /* fallthrough */
        default:
            return Z_STREAM_ERROR;
        }
@@ -1266,7 +1293,7 @@ int flush;
    state->total += out;
    if ((state->wrap & 4) && out)
        strm->adler = state->check =
-            UPDATE(state->check, strm->next_out - out, out);
+            UPDATE_CHECK(state->check, strm->next_out - out, out);
    strm->data_type = (int)state->bits + (state->last ? 64 : 0) +
                      (state->mode == TYPE ? 128 : 0) +
                      (state->mode == LEN_ || state->mode == COPY_ ? 256 : 0);
@@ -1402,6 +1429,7 @@ int ZEXPORT inflateSync(strm)
 z_streamp strm;
 {
    unsigned len;               /* number of bytes to look at or looked at */
+    int flags;                  /* temporary to save header status */
    unsigned long in, out;      /* temporary to save total_in and total_out */
    unsigned char buf[4];       /* to restore bit buffer to byte string */
    struct inflate_state FAR *state;
@@ -1434,9 +1462,15 @@ z_streamp strm;

    /* return no joy or set up to restart inflate() on a new block */
    if (state->have != 4) return Z_DATA_ERROR;
+    if (state->flags == -1)
+        state->wrap = 0;    /* if no header yet, treat as raw */
+    else
+        state->wrap &= ~4;  /* no point in computing a check value now */
+    flags = state->flags;
    in = strm->total_in;  out = strm->total_out;
    inflateReset(strm);
    strm->total_in = in;  strm->total_out = out;
+    state->flags = flags;
    state->mode = TYPE;
    return Z_OK;
 }
@@ -1532,7 +1566,7 @@ int check;

    if (inflateStateCheck(strm)) return Z_STREAM_ERROR;
    state = (struct inflate_state FAR *)strm->state;
-    if (check)
+    if (check && state->wrap)
        state->wrap |= 4;
    else
        state->wrap &= ~4;
@@ -1,5 +1,5 @@
 /* inflate.h -- internal inflate state definition
- * Copyright (C) 1995-2016 Mark Adler
+ * Copyright (C) 1995-2019 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -86,7 +86,8 @@ struct inflate_state {
    int wrap;                   /* bit 0 true for zlib, bit 1 true for gzip,
                                   bit 2 true to validate check value */
    int havedict;               /* true if dictionary provided */
-    int flags;                  /* gzip header method and flags (0 if zlib) */
+    int flags;                  /* gzip header method and flags, 0 if zlib, or
+                                   -1 if raw or no header yet */
    unsigned dmax;              /* zlib header max distance (INFLATE_STRICT) */
    unsigned long check;        /* protected copy of check value */
    unsigned long total;        /* protected copy of output count */
@@ -1,5 +1,5 @@
 /* inftrees.c -- generate Huffman trees for efficient decoding
- * Copyright (C) 1995-2017 Mark Adler
+ * Copyright (C) 1995-2022 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -9,7 +9,7 @@
 #define MAXBITS 15

 const char inflate_copyright[] =
-   " inflate 1.2.11 Copyright 1995-2017 Mark Adler ";
+   " inflate 1.2.13 Copyright 1995-2022 Mark Adler ";
 /*
  If you use the zlib library in a product, an acknowledgment is welcome
  in the documentation of your product. If for some reason you cannot
@@ -62,7 +62,7 @@ unsigned short FAR *work;
        35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
    static const unsigned short lext[31] = { /* Length codes 257..285 extra */
        16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18,
-        19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 77, 202};
+        19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 194, 65};
    static const unsigned short dbase[32] = { /* Distance codes 0..29 base */
        1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
        257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
@@ -38,7 +38,7 @@ typedef struct {
 /* Maximum size of the dynamic table.  The maximum number of code structures is
   1444, which is the sum of 852 for literal/length codes and 592 for distance
   codes.  These values were found by exhaustive searches using the program
-   examples/enough.c found in the zlib distribtution.  The arguments to that
+   examples/enough.c found in the zlib distribution.  The arguments to that
   program are the number of symbols, the initial root table size, and the
   maximum bit length of a code.  "enough 286 9 15" for literal/length codes
   returns returns 852, and "enough 30 6 15" for distance codes returns 592.
@@ -1,5 +1,5 @@
 /* trees.c -- output deflated data using Huffman coding
- * Copyright (C) 1995-2017 Jean-loup Gailly
+ * Copyright (C) 1995-2021 Jean-loup Gailly
 * detect_data_type() function provided freely by Cosmin Truta, 2006
 * For conditions of distribution and use, see copyright notice in zlib.h
 */
@@ -149,7 +149,7 @@ local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
 local void compress_block OF((deflate_state *s, const ct_data *ltree,
                              const ct_data *dtree));
 local int  detect_data_type OF((deflate_state *s));
-local unsigned bi_reverse OF((unsigned value, int length));
+local unsigned bi_reverse OF((unsigned code, int len));
 local void bi_windup      OF((deflate_state *s));
 local void bi_flush       OF((deflate_state *s));

@@ -193,7 +193,7 @@ local void send_bits(s, value, length)
    s->bits_sent += (ulg)length;

    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
-     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
+     * (16 - bi_valid) bits from value, leaving (width - (16 - bi_valid))
     * unused bits in value.
     */
    if (s->bi_valid > (int)Buf_size - length) {
@@ -256,7 +256,7 @@ local void tr_static_init()
    length = 0;
    for (code = 0; code < LENGTH_CODES-1; code++) {
        base_length[code] = length;
-        for (n = 0; n < (1<<extra_lbits[code]); n++) {
+        for (n = 0; n < (1 << extra_lbits[code]); n++) {
            _length_code[length++] = (uch)code;
        }
    }
@@ -265,13 +265,13 @@ local void tr_static_init()
     * in two different ways: code 284 + 5 bits or code 285, so we
     * overwrite length_code[255] to use the best encoding:
     */
-    _length_code[length-1] = (uch)code;
+    _length_code[length - 1] = (uch)code;

    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
    dist = 0;
    for (code = 0 ; code < 16; code++) {
        base_dist[code] = dist;
-        for (n = 0; n < (1<<extra_dbits[code]); n++) {
+        for (n = 0; n < (1 << extra_dbits[code]); n++) {
            _dist_code[dist++] = (uch)code;
        }
    }
@@ -279,11 +279,11 @@ local void tr_static_init()
    dist >>= 7; /* from now on, all distances are divided by 128 */
    for ( ; code < D_CODES; code++) {
        base_dist[code] = dist << 7;
-        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
+        for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
            _dist_code[256 + dist++] = (uch)code;
        }
    }
-    Assert (dist == 256, "tr_static_init: 256+dist != 512");
+    Assert (dist == 256, "tr_static_init: 256 + dist != 512");

    /* Construct the codes of the static literal tree */
    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
@@ -312,7 +312,7 @@ local void tr_static_init()
 }

 /* ===========================================================================
- * Genererate the file trees.h describing the static trees.
+ * Generate the file trees.h describing the static trees.
 */
 #ifdef GEN_TREES_H
 #  ifndef ZLIB_DEBUG
@@ -321,7 +321,7 @@ local void tr_static_init()

 #  define SEPARATOR(i, last, width) \
      ((i) == (last)? "\n};\n\n" :    \
-       ((i) % (width) == (width)-1 ? ",\n" : ", "))
+       ((i) % (width) == (width) - 1 ? ",\n" : ", "))

 void gen_trees_header()
 {
@@ -416,7 +416,7 @@ local void init_block(s)

    s->dyn_ltree[END_BLOCK].Freq = 1;
    s->opt_len = s->static_len = 0L;
-    s->last_lit = s->matches = 0;
+    s->sym_next = s->matches = 0;
 }

 #define SMALLEST 1
@@ -458,7 +458,7 @@ local void pqdownheap(s, tree, k)
    while (j <= s->heap_len) {
        /* Set j to the smallest of the two sons: */
        if (j < s->heap_len &&
-            smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
+            smaller(tree, s->heap[j + 1], s->heap[j], s->depth)) {
            j++;
        }
        /* Exit if v is smaller than both sons */
@@ -507,7 +507,7 @@ local void gen_bitlen(s, desc)
     */
    tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */

-    for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
+    for (h = s->heap_max + 1; h < HEAP_SIZE; h++) {
        n = s->heap[h];
        bits = tree[tree[n].Dad].Len + 1;
        if (bits > max_length) bits = max_length, overflow++;
@@ -518,7 +518,7 @@ local void gen_bitlen(s, desc)

        s->bl_count[bits]++;
        xbits = 0;
-        if (n >= base) xbits = extra[n-base];
+        if (n >= base) xbits = extra[n - base];
        f = tree[n].Freq;
        s->opt_len += (ulg)f * (unsigned)(bits + xbits);
        if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
@@ -530,10 +530,10 @@ local void gen_bitlen(s, desc)

    /* Find the first bit length which could increase: */
    do {
-        bits = max_length-1;
+        bits = max_length - 1;
        while (s->bl_count[bits] == 0) bits--;
-        s->bl_count[bits]--;      /* move one leaf down the tree */
-        s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
+        s->bl_count[bits]--;        /* move one leaf down the tree */
+        s->bl_count[bits + 1] += 2; /* move one overflow item as its brother */
        s->bl_count[max_length]--;
        /* The brother of the overflow item also moves one step up,
         * but this does not affect bl_count[max_length]
@@ -569,7 +569,7 @@ local void gen_bitlen(s, desc)
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
-local void gen_codes (tree, max_code, bl_count)
+local void gen_codes(tree, max_code, bl_count)
    ct_data *tree;             /* the tree to decorate */
    int max_code;              /* largest code with non zero frequency */
    ushf *bl_count;            /* number of codes at each bit length */
@@ -583,13 +583,13 @@ local void gen_codes (tree, max_code, bl_count)
     * without bit reversal.
     */
    for (bits = 1; bits <= MAX_BITS; bits++) {
-        code = (code + bl_count[bits-1]) << 1;
+        code = (code + bl_count[bits - 1]) << 1;
        next_code[bits] = (ush)code;
    }
    /* Check that the bit counts in bl_count are consistent. The last code
     * must be all ones.
     */
-    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
+    Assert (code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
            "inconsistent bit counts");
    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

@@ -600,7 +600,7 @@ local void gen_codes (tree, max_code, bl_count)
        tree[n].Code = (ush)bi_reverse(next_code[len]++, len);

        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
-             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
+            n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len] - 1));
    }
 }

@@ -624,7 +624,7 @@ local void build_tree(s, desc)
    int node;          /* new node being created */

    /* Construct the initial heap, with least frequent element in
-     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
+     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n + 1].
     * heap[0] is not used.
     */
    s->heap_len = 0, s->heap_max = HEAP_SIZE;
@@ -652,7 +652,7 @@ local void build_tree(s, desc)
    }
    desc->max_code = max_code;

-    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
+    /* The elements heap[heap_len/2 + 1 .. heap_len] are leaves of the tree,
     * establish sub-heaps of increasing lengths:
     */
    for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
@@ -700,7 +700,7 @@ local void build_tree(s, desc)
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree.
 */
-local void scan_tree (s, tree, max_code)
+local void scan_tree(s, tree, max_code)
    deflate_state *s;
    ct_data *tree;   /* the tree to be scanned */
    int max_code;    /* and its largest code of non zero frequency */
@@ -714,10 +714,10 @@ local void scan_tree (s, tree, max_code)
    int min_count = 4;         /* min repeat count */

    if (nextlen == 0) max_count = 138, min_count = 3;
-    tree[max_code+1].Len = (ush)0xffff; /* guard */
+    tree[max_code + 1].Len = (ush)0xffff; /* guard */

    for (n = 0; n <= max_code; n++) {
-        curlen = nextlen; nextlen = tree[n+1].Len;
+        curlen = nextlen; nextlen = tree[n + 1].Len;
        if (++count < max_count && curlen == nextlen) {
            continue;
        } else if (count < min_count) {
@@ -745,7 +745,7 @@ local void scan_tree (s, tree, max_code)
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
-local void send_tree (s, tree, max_code)
+local void send_tree(s, tree, max_code)
    deflate_state *s;
    ct_data *tree; /* the tree to be scanned */
    int max_code;       /* and its largest code of non zero frequency */
@@ -758,11 +758,11 @@ local void send_tree (s, tree, max_code)
    int max_count = 7;         /* max repeat count */
    int min_count = 4;         /* min repeat count */

-    /* tree[max_code+1].Len = -1; */  /* guard already set */
+    /* tree[max_code + 1].Len = -1; */  /* guard already set */
    if (nextlen == 0) max_count = 138, min_count = 3;

    for (n = 0; n <= max_code; n++) {
-        curlen = nextlen; nextlen = tree[n+1].Len;
+        curlen = nextlen; nextlen = tree[n + 1].Len;
        if (++count < max_count && curlen == nextlen) {
            continue;
        } else if (count < min_count) {
@@ -773,13 +773,13 @@ local void send_tree (s, tree, max_code)
                send_code(s, curlen, s->bl_tree); count--;
            }
            Assert(count >= 3 && count <= 6, " 3_6?");
-            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
+            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count - 3, 2);

        } else if (count <= 10) {
-            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
+            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count - 3, 3);

        } else {
-            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
+            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count - 11, 7);
        }
        count = 0; prevlen = curlen;
        if (nextlen == 0) {
@@ -807,8 +807,8 @@ local int build_bl_tree(s)

    /* Build the bit length tree: */
    build_tree(s, (tree_desc *)(&(s->bl_desc)));
-    /* opt_len now includes the length of the tree representations, except
-     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
+    /* opt_len now includes the length of the tree representations, except the
+     * lengths of the bit lengths codes and the 5 + 5 + 4 bits for the counts.
     */

    /* Determine the number of bit length codes to send. The pkzip format
@@ -819,7 +819,7 @@ local int build_bl_tree(s)
        if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
    }
    /* Update opt_len to include the bit length tree and counts */
-    s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4;
+    s->opt_len += 3*((ulg)max_blindex + 1) + 5 + 5 + 4;
    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
            s->opt_len, s->static_len));

@@ -841,19 +841,19 @@ local void send_all_trees(s, lcodes, dcodes, blcodes)
    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
            "too many codes");
    Tracev((stderr, "\nbl counts: "));
-    send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
-    send_bits(s, dcodes-1,   5);
-    send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
+    send_bits(s, lcodes - 257, 5);  /* not +255 as stated in appnote.txt */
+    send_bits(s, dcodes - 1,   5);
+    send_bits(s, blcodes - 4,  4);  /* not -3 as stated in appnote.txt */
    for (rank = 0; rank < blcodes; rank++) {
        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
        send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
    }
    Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));

-    send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
+    send_tree(s, (ct_data *)s->dyn_ltree, lcodes - 1);  /* literal tree */
    Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));

-    send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
+    send_tree(s, (ct_data *)s->dyn_dtree, dcodes - 1);  /* distance tree */
    Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
 }

@@ -866,17 +866,18 @@ void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
    ulg stored_len;   /* length of input block */
    int last;         /* one if this is the last block for a file */
 {
-    send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
+    send_bits(s, (STORED_BLOCK<<1) + last, 3);  /* send block type */
    bi_windup(s);        /* align on byte boundary */
    put_short(s, (ush)stored_len);
    put_short(s, (ush)~stored_len);
-    zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
+    if (stored_len)
+        zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
    s->pending += stored_len;
 #ifdef ZLIB_DEBUG
    s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
    s->compressed_len += (stored_len + 4) << 3;
    s->bits_sent += 2*16;
-    s->bits_sent += stored_len<<3;
+    s->bits_sent += stored_len << 3;
 #endif
 }

@@ -942,14 +943,17 @@ void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
        max_blindex = build_bl_tree(s);

        /* Determine the best encoding. Compute the block lengths in bytes. */
-        opt_lenb = (s->opt_len+3+7)>>3;
-        static_lenb = (s->static_len+3+7)>>3;
+        opt_lenb = (s->opt_len + 3 + 7) >> 3;
+        static_lenb = (s->static_len + 3 + 7) >> 3;

        Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
                opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
-                s->last_lit));
+                s->sym_next / 3));

-        if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
+#ifndef FORCE_STATIC
+        if (static_lenb <= opt_lenb || s->strategy == Z_FIXED)
+#endif
+            opt_lenb = static_lenb;

    } else {
        Assert(buf != (char*)0, "lost buf");
@@ -959,7 +963,7 @@ void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
 #ifdef FORCE_STORED
    if (buf != (char*)0) { /* force stored block */
 #else
-    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
+    if (stored_len + 4 <= opt_lenb && buf != (char*)0) {
                       /* 4: two words for the lengths */
 #endif
        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
@@ -970,21 +974,17 @@ void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
         */
        _tr_stored_block(s, buf, stored_len, last);

-#ifdef FORCE_STATIC
-    } else if (static_lenb >= 0) { /* force static trees */
-#else
-    } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
-#endif
-        send_bits(s, (STATIC_TREES<<1)+last, 3);
+    } else if (static_lenb == opt_lenb) {
+        send_bits(s, (STATIC_TREES<<1) + last, 3);
        compress_block(s, (const ct_data *)static_ltree,
                       (const ct_data *)static_dtree);
 #ifdef ZLIB_DEBUG
        s->compressed_len += 3 + s->static_len;
 #endif
    } else {
-        send_bits(s, (DYN_TREES<<1)+last, 3);
-        send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
-                       max_blindex+1);
+        send_bits(s, (DYN_TREES<<1) + last, 3);
+        send_all_trees(s, s->l_desc.max_code + 1, s->d_desc.max_code + 1,
+                       max_blindex + 1);
        compress_block(s, (const ct_data *)s->dyn_ltree,
                       (const ct_data *)s->dyn_dtree);
 #ifdef ZLIB_DEBUG
@@ -1003,21 +1003,22 @@ void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
        s->compressed_len += 7;  /* align on byte boundary */
 #endif
    }
-    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
-           s->compressed_len-7*last));
+    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len >> 3,
+           s->compressed_len - 7*last));
 }

 /* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 */
-int ZLIB_INTERNAL _tr_tally (s, dist, lc)
+int ZLIB_INTERNAL _tr_tally(s, dist, lc)
    deflate_state *s;
    unsigned dist;  /* distance of matched string */
-    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
+    unsigned lc;    /* match length - MIN_MATCH or unmatched char (dist==0) */
 {
-    s->d_buf[s->last_lit] = (ush)dist;
-    s->l_buf[s->last_lit++] = (uch)lc;
+    s->sym_buf[s->sym_next++] = (uch)dist;
+    s->sym_buf[s->sym_next++] = (uch)(dist >> 8);
+    s->sym_buf[s->sym_next++] = (uch)lc;
    if (dist == 0) {
        /* lc is the unmatched char */
        s->dyn_ltree[lc].Freq++;
@@ -1029,33 +1030,10 @@ int ZLIB_INTERNAL _tr_tally (s, dist, lc)
               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
               (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");

-        s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
+        s->dyn_ltree[_length_code[lc] + LITERALS + 1].Freq++;
        s->dyn_dtree[d_code(dist)].Freq++;
    }
-
-#ifdef TRUNCATE_BLOCK
-    /* Try to guess if it is profitable to stop the current block here */
-    if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
-        /* Compute an upper bound for the compressed length */
-        ulg out_length = (ulg)s->last_lit*8L;
-        ulg in_length = (ulg)((long)s->strstart - s->block_start);
-        int dcode;
-        for (dcode = 0; dcode < D_CODES; dcode++) {
-            out_length += (ulg)s->dyn_dtree[dcode].Freq *
-                (5L+extra_dbits[dcode]);
-        }
-        out_length >>= 3;
-        Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
-               s->last_lit, in_length, out_length,
-               100L - out_length*100L/in_length));
-        if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
-    }
-#endif
-    return (s->last_lit == s->lit_bufsize-1);
-    /* We avoid equality with lit_bufsize because of wraparound at 64K
-     * on 16 bit machines and because stored blocks are restricted to
-     * 64K-1 bytes.
-     */
+    return (s->sym_next == s->sym_end);
 }

 /* ===========================================================================
@@ -1068,20 +1046,21 @@ local void compress_block(s, ltree, dtree)
 {
    unsigned dist;      /* distance of matched string */
    int lc;             /* match length or unmatched char (if dist == 0) */
-    unsigned lx = 0;    /* running index in l_buf */
+    unsigned sx = 0;    /* running index in sym_buf */
    unsigned code;      /* the code to send */
    int extra;          /* number of extra bits to send */

-    if (s->last_lit != 0) do {
-        dist = s->d_buf[lx];
-        lc = s->l_buf[lx++];
+    if (s->sym_next != 0) do {
+        dist = s->sym_buf[sx++] & 0xff;
+        dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
+        lc = s->sym_buf[sx++];
        if (dist == 0) {
            send_code(s, lc, ltree); /* send a literal byte */
            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
        } else {
            /* Here, lc is the match length - MIN_MATCH */
            code = _length_code[lc];
-            send_code(s, code+LITERALS+1, ltree); /* send the length code */
+            send_code(s, code + LITERALS + 1, ltree);   /* send length code */
            extra = extra_lbits[code];
            if (extra != 0) {
                lc -= base_length[code];
@@ -1099,11 +1078,10 @@ local void compress_block(s, ltree, dtree)
            }
        } /* literal or match pair ? */

-        /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
-        Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
-               "pendingBuf overflow");
+        /* Check that the overlay between pending_buf and sym_buf is ok: */
+        Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");

-    } while (lx < s->last_lit);
+    } while (sx < s->sym_next);

    send_code(s, END_BLOCK, ltree);
 }
@@ -1112,9 +1090,9 @@ local void compress_block(s, ltree, dtree)
 * Check if the data type is TEXT or BINARY, using the following algorithm:
 * - TEXT if the two conditions below are satisfied:
 *    a) There are no non-portable control characters belonging to the
- *       "black list" (0..6, 14..25, 28..31).
+ *       "block list" (0..6, 14..25, 28..31).
 *    b) There is at least one printable character belonging to the
- *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
+ *       "allow list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
 * - BINARY otherwise.
 * - The following partially-portable control characters form a
 *   "gray list" that is ignored in this detection algorithm:
@@ -1124,19 +1102,19 @@ local void compress_block(s, ltree, dtree)
 local int detect_data_type(s)
    deflate_state *s;
 {
-    /* black_mask is the bit mask of black-listed bytes
+    /* block_mask is the bit mask of block-listed bytes
     * set bits 0..6, 14..25, and 28..31
     * 0xf3ffc07f = binary 11110011111111111100000001111111
     */
-    unsigned long black_mask = 0xf3ffc07fUL;
+    unsigned long block_mask = 0xf3ffc07fUL;
    int n;

-    /* Check for non-textual ("black-listed") bytes. */
-    for (n = 0; n <= 31; n++, black_mask >>= 1)
-        if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
+    /* Check for non-textual ("block-listed") bytes. */
+    for (n = 0; n <= 31; n++, block_mask >>= 1)
+        if ((block_mask & 1) && (s->dyn_ltree[n].Freq != 0))
            return Z_BINARY;

-    /* Check for textual ("white-listed") bytes. */
+    /* Check for textual ("allow-listed") bytes. */
    if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
            || s->dyn_ltree[13].Freq != 0)
        return Z_TEXT;
@@ -1144,7 +1122,7 @@ local int detect_data_type(s)
        if (s->dyn_ltree[n].Freq != 0)
            return Z_TEXT;

-    /* There are no "black-listed" or "white-listed" bytes:
+    /* There are no "block-listed" or "allow-listed" bytes:
     * this stream either is empty or has tolerated ("gray-listed") bytes only.
     */
    return Z_BINARY;
@@ -1198,6 +1176,6 @@ local void bi_windup(s)
    s->bi_buf = 0;
    s->bi_valid = 0;
 #ifdef ZLIB_DEBUG
-    s->bits_sent = (s->bits_sent+7) & ~7;
+    s->bits_sent = (s->bits_sent + 7) & ~7;
 #endif
 }
@@ -24,7 +24,7 @@
   Z_DATA_ERROR if the input data was corrupted, including if the input data is
   an incomplete zlib stream.
 */
-int ZEXPORT uncompress2 (dest, destLen, source, sourceLen)
+int ZEXPORT uncompress2(dest, destLen, source, sourceLen)
    Bytef *dest;
    uLongf *destLen;
    const Bytef *source;
@@ -83,7 +83,7 @@ int ZEXPORT uncompress2 (dest, destLen, source, sourceLen)
           err;
 }

-int ZEXPORT uncompress (dest, destLen, source, sourceLen)
+int ZEXPORT uncompress(dest, destLen, source, sourceLen)
    Bytef *dest;
    uLongf *destLen;
    const Bytef *source;
@@ -38,6 +38,9 @@
 #  define crc32                 z_crc32
 #  define crc32_combine         z_crc32_combine
 #  define crc32_combine64       z_crc32_combine64
+#  define crc32_combine_gen     z_crc32_combine_gen
+#  define crc32_combine_gen64   z_crc32_combine_gen64
+#  define crc32_combine_op      z_crc32_combine_op
 #  define crc32_z               z_crc32_z
 #  define deflate               z_deflate
 #  define deflateBound          z_deflateBound
@@ -349,6 +352,9 @@
 #    ifdef FAR
 #      undef FAR
 #    endif
+#    ifndef WIN32_LEAN_AND_MEAN
+#      define WIN32_LEAN_AND_MEAN
+#    endif
 #    include <windows.h>
     /* No need for _export, use ZLIB.DEF instead. */
     /* For complete Windows compatibility, use WINAPI, not __stdcall. */
@@ -467,11 +473,18 @@ typedef uLong FAR uLongf;
 #  undef _LARGEFILE64_SOURCE
 #endif

-#if defined(__WATCOMC__) && !defined(Z_HAVE_UNISTD_H)
-#  define Z_HAVE_UNISTD_H
+#ifndef Z_HAVE_UNISTD_H
+#  ifdef __WATCOMC__
+#    define Z_HAVE_UNISTD_H
+#  endif
+#endif
+#ifndef Z_HAVE_UNISTD_H
+#  if defined(_LARGEFILE64_SOURCE) && !defined(_WIN32)
+#    define Z_HAVE_UNISTD_H
+#  endif
 #endif
 #ifndef Z_SOLO
-#  if defined(Z_HAVE_UNISTD_H) || defined(_LARGEFILE64_SOURCE)
+#  if defined(Z_HAVE_UNISTD_H)
 #    include <unistd.h>         /* for SEEK_*, off_t, and _LFS64_LARGEFILE */
 #    ifdef VMS
 #      include <unixio.h>       /* for off_t */
@@ -1,7 +1,7 @@
 /* zlib.h -- interface of the 'zlib' general purpose compression library
-  version 1.2.11, January 15th, 2017
+  version 1.2.13, October 13th, 2022

-  Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler
+  Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
@@ -37,11 +37,11 @@
 extern "C" {
 #endif

-#define ZLIB_VERSION "1.2.11"
-#define ZLIB_VERNUM 0x12b0
+#define ZLIB_VERSION "1.2.13"
+#define ZLIB_VERNUM 0x12d0
 #define ZLIB_VER_MAJOR 1
 #define ZLIB_VER_MINOR 2
-#define ZLIB_VER_REVISION 11
+#define ZLIB_VER_REVISION 13
 #define ZLIB_VER_SUBREVISION 0

 /*
@@ -276,7 +276,7 @@ ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
  == 0), or after each call of deflate().  If deflate returns Z_OK and with
  zero avail_out, it must be called again after making room in the output
  buffer because there might be more output pending. See deflatePending(),
-  which can be used if desired to determine whether or not there is more ouput
+  which can be used if desired to determine whether or not there is more output
  in that case.

    Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
@@ -543,8 +543,7 @@ ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
                                     int  strategy));

     This is another version of deflateInit with more compression options.  The
-   fields next_in, zalloc, zfree and opaque must be initialized before by the
-   caller.
+   fields zalloc, zfree and opaque must be initialized before by the caller.

     The method parameter is the compression method.  It must be Z_DEFLATED in
   this version of the library.
@@ -661,7 +660,7 @@ ZEXTERN int ZEXPORT deflateGetDictionary OF((z_streamp strm,
   to dictionary.  dictionary must have enough space, where 32768 bytes is
   always enough.  If deflateGetDictionary() is called with dictionary equal to
   Z_NULL, then only the dictionary length is returned, and nothing is copied.
-   Similary, if dictLength is Z_NULL, then it is not set.
+   Similarly, if dictLength is Z_NULL, then it is not set.

     deflateGetDictionary() may return a length less than the window size, even
   when more than the window size in input has been provided. It may return up
@@ -712,11 +711,12 @@ ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
   used to switch between compression and straight copy of the input data, or
   to switch to a different kind of input data requiring a different strategy.
   If the compression approach (which is a function of the level) or the
-   strategy is changed, and if any input has been consumed in a previous
-   deflate() call, then the input available so far is compressed with the old
-   level and strategy using deflate(strm, Z_BLOCK).  There are three approaches
-   for the compression levels 0, 1..3, and 4..9 respectively.  The new level
-   and strategy will take effect at the next call of deflate().
+   strategy is changed, and if there have been any deflate() calls since the
+   state was initialized or reset, then the input available so far is
+   compressed with the old level and strategy using deflate(strm, Z_BLOCK).
+   There are three approaches for the compression levels 0, 1..3, and 4..9
+   respectively.  The new level and strategy will take effect at the next call
+   of deflate().

     If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
   not have enough output space to complete, then the parameter change will not
@@ -865,9 +865,11 @@ ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
   detection, or add 16 to decode only the gzip format (the zlib format will
   return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
   CRC-32 instead of an Adler-32.  Unlike the gunzip utility and gzread() (see
-   below), inflate() will not automatically decode concatenated gzip streams.
-   inflate() will return Z_STREAM_END at the end of the gzip stream.  The state
-   would need to be reset to continue decoding a subsequent gzip stream.
+   below), inflate() will *not* automatically decode concatenated gzip members.
+   inflate() will return Z_STREAM_END at the end of the gzip member.  The state
+   would need to be reset to continue decoding a subsequent gzip member.  This
+   *must* be done if there is more data after a gzip member, in order for the
+   decompression to be compliant with the gzip standard (RFC 1952).

     inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
   memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
@@ -913,7 +915,7 @@ ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
   to dictionary.  dictionary must have enough space, where 32768 bytes is
   always enough.  If inflateGetDictionary() is called with dictionary equal to
   Z_NULL, then only the dictionary length is returned, and nothing is copied.
-   Similary, if dictLength is Z_NULL, then it is not set.
+   Similarly, if dictLength is Z_NULL, then it is not set.

     inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
   stream state is inconsistent.
@@ -1302,14 +1304,14 @@ typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
 /*
 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));

-     Opens a gzip (.gz) file for reading or writing.  The mode parameter is as
-   in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
-   a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
-   compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
-   for fixed code compression as in "wb9F".  (See the description of
-   deflateInit2 for more information about the strategy parameter.)  'T' will
-   request transparent writing or appending with no compression and not using
-   the gzip format.
+     Open the gzip (.gz) file at path for reading and decompressing, or
+   compressing and writing.  The mode parameter is as in fopen ("rb" or "wb")
+   but can also include a compression level ("wb9") or a strategy: 'f' for
+   filtered data as in "wb6f", 'h' for Huffman-only compression as in "wb1h",
+   'R' for run-length encoding as in "wb1R", or 'F' for fixed code compression
+   as in "wb9F".  (See the description of deflateInit2 for more information
+   about the strategy parameter.)  'T' will request transparent writing or
+   appending with no compression and not using the gzip format.

     "a" can be used instead of "w" to request that the gzip stream that will
   be written be appended to the file.  "+" will result in an error, since
@@ -1339,9 +1341,9 @@ ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));

 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
 /*
-     gzdopen associates a gzFile with the file descriptor fd.  File descriptors
-   are obtained from calls like open, dup, creat, pipe or fileno (if the file
-   has been previously opened with fopen).  The mode parameter is as in gzopen.
+     Associate a gzFile with the file descriptor fd.  File descriptors are
+   obtained from calls like open, dup, creat, pipe or fileno (if the file has
+   been previously opened with fopen).  The mode parameter is as in gzopen.

     The next call of gzclose on the returned gzFile will also close the file
   descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
@@ -1362,13 +1364,13 @@ ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));

 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
 /*
-     Set the internal buffer size used by this library's functions.  The
-   default buffer size is 8192 bytes.  This function must be called after
-   gzopen() or gzdopen(), and before any other calls that read or write the
-   file.  The buffer memory allocation is always deferred to the first read or
-   write.  Three times that size in buffer space is allocated.  A larger buffer
-   size of, for example, 64K or 128K bytes will noticeably increase the speed
-   of decompression (reading).
+     Set the internal buffer size used by this library's functions for file to
+   size.  The default buffer size is 8192 bytes.  This function must be called
+   after gzopen() or gzdopen(), and before any other calls that read or write
+   the file.  The buffer memory allocation is always deferred to the first read
+   or write.  Three times that size in buffer space is allocated.  A larger
+   buffer size of, for example, 64K or 128K bytes will noticeably increase the
+   speed of decompression (reading).

     The new buffer size also affects the maximum length for gzprintf().

@@ -1378,9 +1380,9 @@ ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));

 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
 /*
-     Dynamically update the compression level or strategy.  See the description
-   of deflateInit2 for the meaning of these parameters.  Previously provided
-   data is flushed before the parameter change.
+     Dynamically update the compression level and strategy for file.  See the
+   description of deflateInit2 for the meaning of these parameters. Previously
+   provided data is flushed before applying the parameter changes.

     gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
   opened for writing, Z_ERRNO if there is an error writing the flushed data,
@@ -1389,7 +1391,7 @@ ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));

 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
 /*
-     Reads the given number of uncompressed bytes from the compressed file.  If
+     Read and decompress up to len uncompressed bytes from file into buf.  If
   the input file is not in gzip format, gzread copies the given number of
   bytes into the buffer directly from the file.

@@ -1420,11 +1422,11 @@ ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
 ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
                                     gzFile file));
 /*
-     Read up to nitems items of size size from file to buf, otherwise operating
-   as gzread() does.  This duplicates the interface of stdio's fread(), with
-   size_t request and return types.  If the library defines size_t, then
-   z_size_t is identical to size_t.  If not, then z_size_t is an unsigned
-   integer type that can contain a pointer.
+     Read and decompress up to nitems items of size size from file into buf,
+   otherwise operating as gzread() does.  This duplicates the interface of
+   stdio's fread(), with size_t request and return types.  If the library
+   defines size_t, then z_size_t is identical to size_t.  If not, then z_size_t
+   is an unsigned integer type that can contain a pointer.

     gzfread() returns the number of full items read of size size, or zero if
   the end of the file was reached and a full item could not be read, or if
@@ -1435,26 +1437,24 @@ ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,

     In the event that the end of file is reached and only a partial item is
   available at the end, i.e. the remaining uncompressed data length is not a
-   multiple of size, then the final partial item is nevetheless read into buf
+   multiple of size, then the final partial item is nevertheless read into buf
   and the end-of-file flag is set.  The length of the partial item read is not
   provided, but could be inferred from the result of gztell().  This behavior
   is the same as the behavior of fread() implementations in common libraries,
   but it prevents the direct use of gzfread() to read a concurrently written
-   file, reseting and retrying on end-of-file, when size is not 1.
+   file, resetting and retrying on end-of-file, when size is not 1.
 */

-ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
-                                voidpc buf, unsigned len));
+ZEXTERN int ZEXPORT gzwrite OF((gzFile file, voidpc buf, unsigned len));
 /*
-     Writes the given number of uncompressed bytes into the compressed file.
-   gzwrite returns the number of uncompressed bytes written or 0 in case of
-   error.
+     Compress and write the len uncompressed bytes at buf to file. gzwrite
+   returns the number of uncompressed bytes written or 0 in case of error.
 */

 ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
                                      z_size_t nitems, gzFile file));
 /*
-     gzfwrite() writes nitems items of size size from buf to file, duplicating
+     Compress and write nitems items of size size from buf to file, duplicating
   the interface of stdio's fwrite(), with size_t request and return types.  If
   the library defines size_t, then z_size_t is identical to size_t.  If not,
   then z_size_t is an unsigned integer type that can contain a pointer.
@@ -1467,22 +1467,22 @@ ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,

 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
 /*
-     Converts, formats, and writes the arguments to the compressed file under
-   control of the format string, as in fprintf.  gzprintf returns the number of
+     Convert, format, compress, and write the arguments (...) to file under
+   control of the string format, as in fprintf.  gzprintf returns the number of
   uncompressed bytes actually written, or a negative zlib error code in case
   of error.  The number of uncompressed bytes written is limited to 8191, or
   one less than the buffer size given to gzbuffer().  The caller should assure
   that this limit is not exceeded.  If it is exceeded, then gzprintf() will
   return an error (0) with nothing written.  In this case, there may also be a
   buffer overflow with unpredictable consequences, which is possible only if
-   zlib was compiled with the insecure functions sprintf() or vsprintf()
+   zlib was compiled with the insecure functions sprintf() or vsprintf(),
   because the secure snprintf() or vsnprintf() functions were not available.
   This can be determined using zlibCompileFlags().
 */

 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
 /*
-     Writes the given null-terminated string to the compressed file, excluding
+     Compress and write the given null-terminated string s to file, excluding
   the terminating null character.

     gzputs returns the number of characters written, or -1 in case of error.
@@ -1490,11 +1490,12 @@ ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));

 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
 /*
-     Reads bytes from the compressed file until len-1 characters are read, or a
-   newline character is read and transferred to buf, or an end-of-file
-   condition is encountered.  If any characters are read or if len == 1, the
-   string is terminated with a null character.  If no characters are read due
-   to an end-of-file or len < 1, then the buffer is left untouched.
+     Read and decompress bytes from file into buf, until len-1 characters are
+   read, or until a newline character is read and transferred to buf, or an
+   end-of-file condition is encountered.  If any characters are read or if len
+   is one, the string is terminated with a null character.  If no characters
+   are read due to an end-of-file or len is less than one, then the buffer is
+   left untouched.

     gzgets returns buf which is a null-terminated string, or it returns NULL
   for end-of-file or in case of error.  If there was an error, the contents at
@@ -1503,13 +1504,13 @@ ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));

 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
 /*
-     Writes c, converted to an unsigned char, into the compressed file.  gzputc
+     Compress and write c, converted to an unsigned char, into file.  gzputc
   returns the value that was written, or -1 in case of error.
 */

 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
 /*
-     Reads one byte from the compressed file.  gzgetc returns this byte or -1
+     Read and decompress one byte from file.  gzgetc returns this byte or -1
   in case of end of file or error.  This is implemented as a macro for speed.
   As such, it does not do all of the checking the other functions do.  I.e.
   it does not check to see if file is NULL, nor whether the structure file
@@ -1518,8 +1519,8 @@ ZEXTERN int ZEXPORT gzgetc OF((gzFile file));

 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
 /*
-     Push one character back onto the stream to be read as the first character
-   on the next read.  At least one character of push-back is allowed.
+     Push c back onto the stream for file to be read as the first character on
+   the next read.  At least one character of push-back is always allowed.
   gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
   fail if c is -1, and may fail if a character has been pushed but not read
   yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
@@ -1530,9 +1531,9 @@ ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));

 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
 /*
-     Flushes all pending output into the compressed file.  The parameter flush
-   is as in the deflate() function.  The return value is the zlib error number
-   (see function gzerror below).  gzflush is only permitted when writing.
+     Flush all pending output to file.  The parameter flush is as in the
+   deflate() function.  The return value is the zlib error number (see function
+   gzerror below).  gzflush is only permitted when writing.

     If the flush parameter is Z_FINISH, the remaining data is written and the
   gzip stream is completed in the output.  If gzwrite() is called again, a new
@@ -1547,8 +1548,8 @@ ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
                                   z_off_t offset, int whence));

-     Sets the starting position for the next gzread or gzwrite on the given
-   compressed file.  The offset represents a number of bytes in the
+     Set the starting position to offset relative to whence for the next gzread
+   or gzwrite on file.  The offset represents a number of bytes in the
   uncompressed data stream.  The whence parameter is defined as in lseek(2);
   the value SEEK_END is not supported.

@@ -1565,18 +1566,18 @@ ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,

 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
 /*
-     Rewinds the given file. This function is supported only for reading.
+     Rewind file. This function is supported only for reading.

-     gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
+     gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET).
 */

 /*
 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));

-     Returns the starting position for the next gzread or gzwrite on the given
-   compressed file.  This position represents a number of bytes in the
-   uncompressed data stream, and is zero when starting, even if appending or
-   reading a gzip stream from the middle of a file using gzdopen().
+     Return the starting position for the next gzread or gzwrite on file.
+   This position represents a number of bytes in the uncompressed data stream,
+   and is zero when starting, even if appending or reading a gzip stream from
+   the middle of a file using gzdopen().

     gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
 */
@@ -1584,22 +1585,22 @@ ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
 /*
 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));

-     Returns the current offset in the file being read or written.  This offset
-   includes the count of bytes that precede the gzip stream, for example when
-   appending or when using gzdopen() for reading.  When reading, the offset
-   does not include as yet unused buffered input.  This information can be used
-   for a progress indicator.  On error, gzoffset() returns -1.
+     Return the current compressed (actual) read or write offset of file.  This
+   offset includes the count of bytes that precede the gzip stream, for example
+   when appending or when using gzdopen() for reading.  When reading, the
+   offset does not include as yet unused buffered input.  This information can
+   be used for a progress indicator.  On error, gzoffset() returns -1.
 */

 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
 /*
-     Returns true (1) if the end-of-file indicator has been set while reading,
-   false (0) otherwise.  Note that the end-of-file indicator is set only if the
-   read tried to go past the end of the input, but came up short.  Therefore,
-   just like feof(), gzeof() may return false even if there is no more data to
-   read, in the event that the last read request was for the exact number of
-   bytes remaining in the input file.  This will happen if the input file size
-   is an exact multiple of the buffer size.
+     Return true (1) if the end-of-file indicator for file has been set while
+   reading, false (0) otherwise.  Note that the end-of-file indicator is set
+   only if the read tried to go past the end of the input, but came up short.
+   Therefore, just like feof(), gzeof() may return false even if there is no
+   more data to read, in the event that the last read request was for the exact
+   number of bytes remaining in the input file.  This will happen if the input
+   file size is an exact multiple of the buffer size.

     If gzeof() returns true, then the read functions will return no more data,
   unless the end-of-file indicator is reset by gzclearerr() and the input file
@@ -1608,7 +1609,7 @@ ZEXTERN int ZEXPORT gzeof OF((gzFile file));

 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
 /*
-     Returns true (1) if file is being copied directly while reading, or false
+     Return true (1) if file is being copied directly while reading, or false
   (0) if file is a gzip stream being decompressed.

     If the input file is empty, gzdirect() will return true, since the input
@@ -1629,8 +1630,8 @@ ZEXTERN int ZEXPORT gzdirect OF((gzFile file));

 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
 /*
-     Flushes all pending output if necessary, closes the compressed file and
-   deallocates the (de)compression state.  Note that once file is closed, you
+     Flush all pending output for file, if necessary, close file and
+   deallocate the (de)compression state.  Note that once file is closed, you
   cannot call gzerror with file, since its structures have been deallocated.
   gzclose must not be called more than once on the same file, just as free
   must not be called more than once on the same allocation.
@@ -1654,10 +1655,10 @@ ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));

 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
 /*
-     Returns the error message for the last error which occurred on the given
-   compressed file.  errnum is set to zlib error number.  If an error occurred
-   in the file system and not in the compression library, errnum is set to
-   Z_ERRNO and the application may consult errno to get the exact error code.
+     Return the error message for the last error which occurred on file.
+   errnum is set to zlib error number.  If an error occurred in the file system
+   and not in the compression library, errnum is set to Z_ERRNO and the
+   application may consult errno to get the exact error code.

     The application must not modify the returned string.  Future calls to
   this function may invalidate the previously returned string.  If file is
@@ -1670,7 +1671,7 @@ ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));

 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
 /*
-     Clears the error and end-of-file flags for file.  This is analogous to the
+     Clear the error and end-of-file flags for file.  This is analogous to the
   clearerr() function in stdio.  This is useful for continuing to read a gzip
   file that is being written concurrently.
 */
@@ -1688,8 +1689,9 @@ ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
 /*
     Update a running Adler-32 checksum with the bytes buf[0..len-1] and
-   return the updated checksum.  If buf is Z_NULL, this function returns the
-   required initial value for the checksum.
+   return the updated checksum. An Adler-32 value is in the range of a 32-bit
+   unsigned integer. If buf is Z_NULL, this function returns the required
+   initial value for the checksum.

     An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
   much faster.
@@ -1722,12 +1724,13 @@ ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
   negative, the result has no meaning or utility.
 */

-ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
+ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
 /*
     Update a running CRC-32 with the bytes buf[0..len-1] and return the
-   updated CRC-32.  If buf is Z_NULL, this function returns the required
-   initial value for the crc.  Pre- and post-conditioning (one's complement) is
-   performed within this function so it shouldn't be done by the application.
+   updated CRC-32. A CRC-32 value is in the range of a 32-bit unsigned integer.
+   If buf is Z_NULL, this function returns the required initial value for the
+   crc. Pre- and post-conditioning (one's complement) is performed within this
+   function so it shouldn't be done by the application.

   Usage example:

@@ -1739,7 +1742,7 @@ ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
     if (crc != original_crc) error();
 */

-ZEXTERN uLong ZEXPORT crc32_z OF((uLong adler, const Bytef *buf,
+ZEXTERN uLong ZEXPORT crc32_z OF((uLong crc, const Bytef *buf,
                                  z_size_t len));
 /*
     Same as crc32(), but with a size_t length.
@@ -1755,6 +1758,20 @@ ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
   len2.
 */

+/*
+ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t len2));
+
+     Return the operator corresponding to length len2, to be used with
+   crc32_combine_op().
+*/
+
+ZEXTERN uLong ZEXPORT crc32_combine_op OF((uLong crc1, uLong crc2, uLong op));
+/*
+     Give the same result as crc32_combine(), using op in place of len2. op is
+   is generated from len2 by crc32_combine_gen(). This will be faster than
+   crc32_combine() if the generated op is used more than once.
+*/
+

                        /* various hacks, don't look :) */

@@ -1842,6 +1859,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
   ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
   ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
   ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
+   ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off64_t));
 #endif

 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
@@ -1852,6 +1870,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
 #    define z_gzoffset z_gzoffset64
 #    define z_adler32_combine z_adler32_combine64
 #    define z_crc32_combine z_crc32_combine64
+#    define z_crc32_combine_gen z_crc32_combine_gen64
 #  else
 #    define gzopen gzopen64
 #    define gzseek gzseek64
@@ -1859,6 +1878,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
 #    define gzoffset gzoffset64
 #    define adler32_combine adler32_combine64
 #    define crc32_combine crc32_combine64
+#    define crc32_combine_gen crc32_combine_gen64
 #  endif
 #  ifndef Z_LARGE64
     ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
@@ -1867,6 +1887,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
     ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
     ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
     ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
+     ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off_t));
 #  endif
 #else
   ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
@@ -1875,12 +1896,14 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
   ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
   ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
   ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
+   ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t));
 #endif

 #else /* Z_SOLO */

   ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
   ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
+   ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t));

 #endif /* !Z_SOLO */

@@ -1890,10 +1913,10 @@ ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
 ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
 ZEXTERN int            ZEXPORT inflateValidate OF((z_streamp, int));
-ZEXTERN unsigned long  ZEXPORT inflateCodesUsed OF ((z_streamp));
+ZEXTERN unsigned long  ZEXPORT inflateCodesUsed OF((z_streamp));
 ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
 ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
-#if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(Z_SOLO)
+#if defined(_WIN32) && !defined(Z_SOLO)
 ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
                                            const char *mode));
 #endif
@@ -61,9 +61,11 @@ uLong ZEXPORT zlibCompileFlags()
 #ifdef ZLIB_DEBUG
    flags += 1 << 8;
 #endif
+    /*
 #if defined(ASMV) || defined(ASMINF)
    flags += 1 << 9;
 #endif
+     */
 #ifdef ZLIB_WINAPI
    flags += 1 << 10;
 #endif
@@ -119,7 +121,7 @@ uLong ZEXPORT zlibCompileFlags()
 #  endif
 int ZLIB_INTERNAL z_verbose = verbose;

-void ZLIB_INTERNAL z_error (m)
+void ZLIB_INTERNAL z_error(m)
    char *m;
 {
    fprintf(stderr, "%s\n", m);
@@ -137,7 +139,7 @@ const char * ZEXPORT zError(err)
 }

 #if defined(_WIN32_WCE) && _WIN32_WCE < 0x800
-    /* The Microsoft C Run-Time Library for Windows CE doesn't have
+    /* The older Microsoft C Run-Time Library for Windows CE doesn't have
     * errno.  We define it as a global variable to simplify porting.
     * Its value is always 0 and should not be used.
     */
@@ -214,7 +216,7 @@ local ptr_table table[MAX_PTR];
 * a protected system like OS/2. Use Microsoft C instead.
 */

-voidpf ZLIB_INTERNAL zcalloc (voidpf opaque, unsigned items, unsigned size)
+voidpf ZLIB_INTERNAL zcalloc(voidpf opaque, unsigned items, unsigned size)
 {
    voidpf buf;
    ulg bsize = (ulg)items*size;
@@ -240,7 +242,7 @@ voidpf ZLIB_INTERNAL zcalloc (voidpf opaque, unsigned items, unsigned size)
    return buf;
 }

-void ZLIB_INTERNAL zcfree (voidpf opaque, voidpf ptr)
+void ZLIB_INTERNAL zcfree(voidpf opaque, voidpf ptr)
 {
    int n;

@@ -277,13 +279,13 @@ void ZLIB_INTERNAL zcfree (voidpf opaque, voidpf ptr)
 #  define _hfree   hfree
 #endif

-voidpf ZLIB_INTERNAL zcalloc (voidpf opaque, uInt items, uInt size)
+voidpf ZLIB_INTERNAL zcalloc(voidpf opaque, uInt items, uInt size)
 {
    (void)opaque;
    return _halloc((long)items, size);
 }

-void ZLIB_INTERNAL zcfree (voidpf opaque, voidpf ptr)
+void ZLIB_INTERNAL zcfree(voidpf opaque, voidpf ptr)
 {
    (void)opaque;
    _hfree(ptr);
@@ -302,7 +304,7 @@ extern voidp  calloc OF((uInt items, uInt size));
 extern void   free   OF((voidpf ptr));
 #endif

-voidpf ZLIB_INTERNAL zcalloc (opaque, items, size)
+voidpf ZLIB_INTERNAL zcalloc(opaque, items, size)
    voidpf opaque;
    unsigned items;
    unsigned size;
@@ -312,7 +314,7 @@ voidpf ZLIB_INTERNAL zcalloc (opaque, items, size)
                              (voidpf)calloc(items, size);
 }

-void ZLIB_INTERNAL zcfree (opaque, ptr)
+void ZLIB_INTERNAL zcfree(opaque, ptr)
    voidpf opaque;
    voidpf ptr;
 {
@@ -1,5 +1,5 @@
 /* zutil.h -- internal interface and configuration of the compression library
- * Copyright (C) 1995-2016 Jean-loup Gailly, Mark Adler
+ * Copyright (C) 1995-2022 Jean-loup Gailly, Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

@@ -29,10 +29,6 @@
 #  include <stdlib.h>
 #endif

-#ifdef Z_SOLO
-   typedef long ptrdiff_t;  /* guess -- will be caught if guess is wrong */
-#endif
-
 #ifndef local
 #  define local static
 #endif
@@ -46,6 +42,17 @@ typedef unsigned short ush;
 typedef ush FAR ushf;
 typedef unsigned long  ulg;

+#if !defined(Z_U8) && !defined(Z_SOLO) && defined(STDC)
+#  include <limits.h>
+#  if (ULONG_MAX == 0xffffffffffffffff)
+#    define Z_U8 unsigned long
+#  elif (ULLONG_MAX == 0xffffffffffffffff)
+#    define Z_U8 unsigned long long
+#  elif (UINT_MAX == 0xffffffffffffffff)
+#    define Z_U8 unsigned
+#  endif
+#endif
+
 extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
 /* (size given to avoid silly warnings with Visual C++) */

@@ -169,13 +176,7 @@ extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */

 #if (defined(_MSC_VER) && (_MSC_VER > 600)) && !defined __INTERIX
 #  if defined(_WIN32_WCE)
-#    if _WIN32_WCE < 0x800
-#      define fdopen(fd,mode) NULL /* No fdopen() */
-#      ifndef _PTRDIFF_T_DEFINED
-         typedef int ptrdiff_t;
-#        define _PTRDIFF_T_DEFINED
-#      endif
-#  endif
+#    define fdopen(fd,mode) NULL /* No fdopen() */
 #  else
 #    define fdopen(fd,type)  _fdopen(fd,type)
 #  endif
@@ -192,6 +193,7 @@ extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
    (!defined(_LARGEFILE64_SOURCE) || _LFS64_LARGEFILE-0 == 0)
    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
+    ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off_t));
 #endif

        /* common defaults */
@@ -244,7 +244,7 @@ OCV_OPTION(WITH_AVFOUNDATION "Use AVFoundation for Video I/O (iOS/Mac)" ON
 OCV_OPTION(WITH_CARBON "Use Carbon for UI instead of Cocoa (OBSOLETE)" OFF
  VISIBLE_IF (APPLE OR HAVE_COCOA)
  VERIFY HAVE_CARBON)
-OCV_OPTION(WITH_CAROTENE "Use NVidia carotene acceleration library for ARM platform" ON
+OCV_OPTION(WITH_CAROTENE "Use NVidia carotene acceleration library for ARM platform" (NOT CV_DISABLE_OPTIMIZATION)
  VISIBLE_IF (ARM OR AARCH64) AND NOT IOS AND NOT (CMAKE_VERSION VERSION_LESS "2.8.11"))
 OCV_OPTION(WITH_CPUFEATURES "Use cpufeatures Android library" ON
  VISIBLE_IF ANDROID
@@ -291,12 +291,10 @@ OCV_OPTION(WITH_IPP "Include Intel IPP support" (NOT MINGW AND NOT CV_DISABLE_OP
 OCV_OPTION(WITH_HALIDE "Include Halide support" OFF
  VISIBLE_IF TRUE
  VERIFY HAVE_HALIDE)
-OCV_OPTION(WITH_INF_ENGINE "Include Intel Inference Engine support" OFF
+# replacement for deprecated options: WITH_INF_ENGINE, WITH_NGRAPH
+OCV_OPTION(WITH_OPENVINO "Include Intel OpenVINO toolkit support" (WITH_INF_ENGINE)
  VISIBLE_IF TRUE
-  VERIFY INF_ENGINE_TARGET)
-OCV_OPTION(WITH_NGRAPH "Include nGraph support" WITH_INF_ENGINE
-  VISIBLE_IF TRUE
-  VERIFY TARGET ngraph::ngraph)
+  VERIFY TARGET ocv.3rdparty.openvino)
 OCV_OPTION(WITH_JASPER "Include JPEG2K support" ON
  VISIBLE_IF NOT IOS
  VERIFY HAVE_JASPER)
@@ -764,7 +762,7 @@ if(WITH_HALIDE)
 endif()

 # --- Inference Engine ---
-if(WITH_INF_ENGINE)
+if(WITH_INF_ENGINE OR WITH_OPENVINO)
  include(cmake/OpenCVDetectInferenceEngine.cmake)
 endif()

@@ -1524,54 +1522,61 @@ if(WITH_HALIDE OR HAVE_HALIDE)
  status("    Halide:"     HAVE_HALIDE      THEN "YES (${HALIDE_LIBRARIES} ${HALIDE_INCLUDE_DIRS})" ELSE NO)
 endif()

-if(WITH_INF_ENGINE OR INF_ENGINE_TARGET)
-  if(INF_ENGINE_TARGET)
-    list(GET INF_ENGINE_TARGET 0 ie_target)
-    set(__msg "YES (${INF_ENGINE_RELEASE} / ${INF_ENGINE_VERSION})")
-    get_target_property(_lib ${ie_target} IMPORTED_LOCATION)
-    get_target_property(_lib_imp_rel ${ie_target} IMPORTED_IMPLIB_RELEASE)
-    get_target_property(_lib_imp_dbg ${ie_target} IMPORTED_IMPLIB_DEBUG)
-    get_target_property(_lib_rel ${ie_target} IMPORTED_LOCATION_RELEASE)
-    get_target_property(_lib_dbg ${ie_target} IMPORTED_LOCATION_DEBUG)
-    ocv_build_features_string(_lib
-      IF _lib THEN "${_lib}"
-      IF _lib_imp_rel AND _lib_imp_dbg THEN "${_lib_imp_rel} / ${_lib_imp_dbg}"
-      IF _lib_rel AND _lib_dbg THEN "${_lib_rel} / ${_lib_dbg}"
-      IF _lib_rel  THEN "${_lib_rel}"
-      IF _lib_dbg  THEN "${_lib_dbg}"
-      ELSE "unknown"
-    )
-    get_target_property(_inc ${ie_target} INTERFACE_INCLUDE_DIRECTORIES)
-    status("    Inference Engine:" "${__msg}")
-    status("        * libs:" "${_lib}")
-    status("        * includes:" "${_inc}")
-  else()
-    status("    Inference Engine:"     "NO")
+if(HAVE_OPENVINO
+    OR (WITH_OPENVINO AND NOT WITH_INF_ENGINE AND NOT INF_ENGINE_TARGET)
+)
+  status("    OpenVINO:" TARGET openvino::runtime THEN "YES (${OpenVINO_VERSION})" ELSE "NO")
+else()
+  if(WITH_INF_ENGINE OR INF_ENGINE_TARGET)
+    if(INF_ENGINE_TARGET)
+      list(GET INF_ENGINE_TARGET 0 ie_target)
+      set(__msg "YES (${INF_ENGINE_RELEASE} / ${INF_ENGINE_VERSION})")
+      ocv_get_imported_target(ie_target "${ie_target}")
+      get_target_property(_lib ${ie_target} IMPORTED_LOCATION)
+      get_target_property(_lib_imp_rel ${ie_target} IMPORTED_IMPLIB_RELEASE)
+      get_target_property(_lib_imp_dbg ${ie_target} IMPORTED_IMPLIB_DEBUG)
+      get_target_property(_lib_rel ${ie_target} IMPORTED_LOCATION_RELEASE)
+      get_target_property(_lib_dbg ${ie_target} IMPORTED_LOCATION_DEBUG)
+      ocv_build_features_string(_lib
+        IF _lib THEN "${_lib}"
+        IF _lib_imp_rel AND _lib_imp_dbg THEN "${_lib_imp_rel} / ${_lib_imp_dbg}"
+        IF _lib_rel AND _lib_dbg THEN "${_lib_rel} / ${_lib_dbg}"
+        IF _lib_rel  THEN "${_lib_rel}"
+        IF _lib_dbg  THEN "${_lib_dbg}"
+        ELSE "unknown"
+      )
+      get_target_property(_inc ${ie_target} INTERFACE_INCLUDE_DIRECTORIES)
+      status("    Inference Engine:" "${__msg}")
+      status("        * libs:" "${_lib}")
+      status("        * includes:" "${_inc}")
+    else()
+      status("    Inference Engine:"     "NO")
+    endif()
  endif()
-endif()
-if(WITH_NGRAPH OR HAVE_NGRAPH)
-  if(HAVE_NGRAPH)
-    set(__target ngraph::ngraph)
-    set(__msg "YES (${ngraph_VERSION})")
-    get_target_property(_lib ${__target} IMPORTED_LOCATION)
-    get_target_property(_lib_imp_rel ${__target} IMPORTED_IMPLIB_RELEASE)
-    get_target_property(_lib_imp_dbg ${__target} IMPORTED_IMPLIB_DEBUG)
-    get_target_property(_lib_rel ${__target} IMPORTED_LOCATION_RELEASE)
-    get_target_property(_lib_dbg ${__target} IMPORTED_LOCATION_DEBUG)
-    ocv_build_features_string(_lib
-      IF _lib THEN "${_lib}"
-      IF _lib_imp_rel AND _lib_imp_dbg THEN "${_lib_imp_rel} / ${_lib_imp_dbg}"
-      IF _lib_rel AND _lib_dbg THEN "${_lib_rel} / ${_lib_dbg}"
-      IF _lib_rel  THEN "${_lib_rel}"
-      IF _lib_dbg  THEN "${_lib_dbg}"
-      ELSE "unknown"
-    )
-    get_target_property(_inc ${__target} INTERFACE_INCLUDE_DIRECTORIES)
-    status("    nGraph:" "${__msg}")
-    status("        * libs:" "${_lib}")
-    status("        * includes:" "${_inc}")
-  else()
-    status("    nGraph:"     "NO")
+  if(WITH_NGRAPH OR HAVE_NGRAPH)
+    if(HAVE_NGRAPH)
+      ocv_get_imported_target(__target ngraph::ngraph)
+      set(__msg "YES (${ngraph_VERSION})")
+      get_target_property(_lib ${__target} IMPORTED_LOCATION)
+      get_target_property(_lib_imp_rel ${__target} IMPORTED_IMPLIB_RELEASE)
+      get_target_property(_lib_imp_dbg ${__target} IMPORTED_IMPLIB_DEBUG)
+      get_target_property(_lib_rel ${__target} IMPORTED_LOCATION_RELEASE)
+      get_target_property(_lib_dbg ${__target} IMPORTED_LOCATION_DEBUG)
+      ocv_build_features_string(_lib
+        IF _lib THEN "${_lib}"
+        IF _lib_imp_rel AND _lib_imp_dbg THEN "${_lib_imp_rel} / ${_lib_imp_dbg}"
+        IF _lib_rel AND _lib_dbg THEN "${_lib_rel} / ${_lib_dbg}"
+        IF _lib_rel  THEN "${_lib_rel}"
+        IF _lib_dbg  THEN "${_lib_dbg}"
+        ELSE "unknown"
+      )
+      get_target_property(_inc ${__target} INTERFACE_INCLUDE_DIRECTORIES)
+      status("    nGraph:" "${__msg}")
+      status("        * libs:" "${_lib}")
+      status("        * includes:" "${_inc}")
+    else()
+      status("    nGraph:"     "NO")
+    endif()
  endif()
 endif()

@@ -7,13 +7,13 @@ copy or use the software.
               For Open Source Computer Vision Library
                       (3-clause BSD License)

-Copyright (C) 2000-2021, Intel Corporation, all rights reserved.
+Copyright (C) 2000-2022, Intel Corporation, all rights reserved.
 Copyright (C) 2009-2011, Willow Garage Inc., all rights reserved.
 Copyright (C) 2009-2016, NVIDIA Corporation, all rights reserved.
 Copyright (C) 2010-2013, Advanced Micro Devices, Inc., all rights reserved.
-Copyright (C) 2015-2021, OpenCV Foundation, all rights reserved.
+Copyright (C) 2015-2023, OpenCV Foundation, all rights reserved.
 Copyright (C) 2015-2016, Itseez Inc., all rights reserved.
-Copyright (C) 2019-2021, Xperience AI, all rights reserved.
+Copyright (C) 2019-2023, Xperience AI, all rights reserved.
 Third party copyrights are property of their respective owners.

 Redistribution and use in source and binary forms, with or without modification,
@@ -70,7 +70,7 @@ using namespace cv;

 static int icvMkDir( const char* filename )
 {
-    char path[PATH_MAX];
+    char path[PATH_MAX+1];
    char* p;
    int pos;

@@ -83,7 +83,8 @@ static int icvMkDir( const char* filename )
    mode = 0755;
 #endif /* _WIN32 */

-    strcpy( path, filename );
+    path[0] = '\0';
+    strncat( path, filename, PATH_MAX );

    p = path;
    for( ; ; )
@@ -252,7 +252,7 @@ bool CvCascadeClassifier::train( const string _cascadeDirName,
            fs << "}";
        }
        // save current stage
-        char buf[10];
+        char buf[32];
        sprintf(buf, "%s%d", "stage", i );
        string stageFilename = dirName + buf + ".xml";
        FileStorage fs( stageFilename, FileStorage::WRITE );
@@ -54,7 +54,7 @@ bool CvCascadeImageReader::NegReader::nextImg()
    size_t count = imgFilenames.size();
    for( size_t i = 0; i < count; i++ )
    {
-        src = imread( imgFilenames[last++], 0 );
+        src = imread( imgFilenames[last++], IMREAD_GRAYSCALE );
        if( src.empty() ){
            last %= count;
            continue;
@@ -86,6 +86,9 @@ int main( int argc, const char** argv )
        "{ image i        |      | (required) path to reference image }"
        "{ model m        |      | (required) path to cascade xml file }"
        "{ data d         |      | (optional) path to video output folder }"
+        "{ ext            | avi  | (optional) output video file extension e.g. avi (default) or mp4 }"
+        "{ fourcc         | XVID | (optional) output video file's 4-character codec e.g. XVID (default) or H264 }"
+        "{ fps            |   15 | (optional) output video file's frames-per-second rate }"
    );
    // Read in the input arguments
    if (parser.has("help")){
@@ -96,7 +99,9 @@ int main( int argc, const char** argv )
    string model(parser.get<string>("model"));
    string output_folder(parser.get<string>("data"));
    string image_ref = (parser.get<string>("image"));
-    if (model.empty() || image_ref.empty()){
+    string fourcc = (parser.get<string>("fourcc"));
+    int fps = parser.get<int>("fps");
+    if (model.empty() || image_ref.empty() || fourcc.size()!=4 || fps<1){
        parser.printMessage();
        printLimits();
        return -1;
@@ -166,11 +171,19 @@ int main( int argc, const char** argv )
    // each stage, containing all weak classifiers for that stage.
    bool draw_planes = false;
    stringstream output_video;
-    output_video << output_folder << "model_visualization.avi";
+    output_video << output_folder << "model_visualization." << parser.get<string>("ext");
    VideoWriter result_video;
    if( output_folder.compare("") != 0 ){
        draw_planes = true;
-        result_video.open(output_video.str(), VideoWriter::fourcc('X','V','I','D'), 15, Size(reference_image.cols * resize_factor, reference_image.rows * resize_factor), false);
+        result_video.open(output_video.str(), VideoWriter::fourcc(fourcc[0],fourcc[1],fourcc[2],fourcc[3]), fps, visualization.size(), false);
+        if (!result_video.isOpened()){
+            cerr << "the output video '" << output_video.str() << "' could not be opened."
+                 << " fourcc=" << fourcc
+                 << " fps=" << fps
+                 << " frameSize=" << visualization.size()
+                 << endl;
+            return -1;
+        }
    }

    if(haar){
@@ -46,7 +46,7 @@

 set(CPU_ALL_OPTIMIZATIONS "SSE;SSE2;SSE3;SSSE3;SSE4_1;SSE4_2;POPCNT;AVX;FP16;AVX2;FMA3;AVX_512F")
 list(APPEND CPU_ALL_OPTIMIZATIONS "AVX512_COMMON;AVX512_KNL;AVX512_KNM;AVX512_SKX;AVX512_CNL;AVX512_CLX;AVX512_ICL")
-list(APPEND CPU_ALL_OPTIMIZATIONS NEON VFPV3 FP16)
+list(APPEND CPU_ALL_OPTIMIZATIONS NEON VFPV3 FP16 NEON_DOTPROD)
 list(APPEND CPU_ALL_OPTIMIZATIONS MSA)
 list(APPEND CPU_ALL_OPTIMIZATIONS VSX VSX3)
 list(REMOVE_DUPLICATES CPU_ALL_OPTIMIZATIONS)
@@ -326,6 +326,7 @@ if(X86 OR X86_64)
 elseif(ARM OR AARCH64)
  ocv_update(CPU_NEON_TEST_FILE "${OpenCV_SOURCE_DIR}/cmake/checks/cpu_neon.cpp")
  ocv_update(CPU_FP16_TEST_FILE "${OpenCV_SOURCE_DIR}/cmake/checks/cpu_fp16.cpp")
+  ocv_update(CPU_NEON_DOTPROD_TEST_FILE "${OpenCV_SOURCE_DIR}/cmake/checks/cpu_dotprod.cpp")
  if(NOT AARCH64)
    ocv_update(CPU_KNOWN_OPTIMIZATIONS "VFPV3;NEON;FP16")
    if(NOT MSVC)
@@ -337,9 +338,11 @@ elseif(ARM OR AARCH64)
    endif()
    ocv_update(CPU_FP16_IMPLIES "NEON")
  else()
-    ocv_update(CPU_KNOWN_OPTIMIZATIONS "NEON;FP16")
+    ocv_update(CPU_KNOWN_OPTIMIZATIONS "NEON;FP16;NEON_DOTPROD")
    ocv_update(CPU_NEON_FLAGS_ON "")
    ocv_update(CPU_FP16_IMPLIES "NEON")
+    ocv_update(CPU_NEON_DOTPROD_FLAGS_ON "-march=armv8.2-a+dotprod")
+    ocv_update(CPU_NEON_DOTPROD_IMPLIES "NEON")
    set(CPU_BASELINE "NEON;FP16" CACHE STRING "${HELP_CPU_BASELINE}")
  endif()
 elseif(MIPS)
@@ -677,7 +680,7 @@ macro(ocv_compiler_optimization_process_sources SOURCES_VAR_NAME LIBS_VAR_NAME T
          if(fname_LOWER MATCHES "\\.${OPT_LOWER}\\.cpp$")
 #message("${fname} BASELINE-${OPT}")
            set(__opt_found 1)
-            list(APPEND __result "${fname}")
+            list(APPEND __result_${OPT} "${fname}")
            break()
          endif()
        endforeach()
@@ -711,7 +714,7 @@ macro(ocv_compiler_optimization_process_sources SOURCES_VAR_NAME LIBS_VAR_NAME T
    endif()
  endforeach()

-  foreach(OPT ${CPU_DISPATCH_FINAL})
+  foreach(OPT ${CPU_BASELINE_FINAL} ${CPU_DISPATCH_FINAL})
    if(__result_${OPT})
 #message("${OPT}: ${__result_${OPT}}")
      if(CMAKE_GENERATOR MATCHES "^Visual"
@@ -119,12 +119,12 @@ if(CV_GCC OR CV_CLANG)
    # we want.
    add_extra_compiler_option(-Wall)
  endif()
-  add_extra_compiler_option(-Werror=return-type)
-  add_extra_compiler_option(-Werror=non-virtual-dtor)
-  add_extra_compiler_option(-Werror=address)
-  add_extra_compiler_option(-Werror=sequence-point)
+  add_extra_compiler_option(-Wreturn-type)
+  add_extra_compiler_option(-Wnon-virtual-dtor)
+  add_extra_compiler_option(-Waddress)
+  add_extra_compiler_option(-Wsequence-point)
  add_extra_compiler_option(-Wformat)
-  add_extra_compiler_option(-Werror=format-security -Wformat)
+  add_extra_compiler_option(-Wformat-security -Wformat)
  add_extra_compiler_option(-Wmissing-declarations)
  add_extra_compiler_option(-Wmissing-prototypes)
  add_extra_compiler_option(-Wstrict-prototypes)
@@ -134,7 +134,7 @@ if(CV_GCC OR CV_CLANG)
  add_extra_compiler_option(-Wshadow)
  add_extra_compiler_option(-Wsign-promo)
  add_extra_compiler_option(-Wuninitialized)
-  if(CV_GCC AND (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 6.0) AND (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.0))
+  if(CV_GCC AND (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 6.0) AND (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.0 OR ARM))
    add_extra_compiler_option(-Wno-psabi)
  endif()
  if(HAVE_CXX11)
@@ -360,6 +360,22 @@ if(NOT OPENCV_SKIP_LINK_AS_NEEDED)
  endif()
 endif()

+# Apply "-Wl,--no-undefined" linker flags: https://github.com/opencv/opencv/pull/21347
+if(NOT OPENCV_SKIP_LINK_NO_UNDEFINED)
+  if(UNIX AND (NOT APPLE OR NOT CMAKE_VERSION VERSION_LESS "3.2"))
+    set(_option "-Wl,--no-undefined")
+    set(_saved_CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS}")
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${_option}")  # requires CMake 3.2+ and CMP0056
+    ocv_check_compiler_flag(CXX "" HAVE_LINK_NO_UNDEFINED)
+    set(CMAKE_EXE_LINKER_FLAGS "${_saved_CMAKE_EXE_LINKER_FLAGS}")
+    if(HAVE_LINK_NO_UNDEFINED)
+      set(OPENCV_EXTRA_EXE_LINKER_FLAGS "${OPENCV_EXTRA_EXE_LINKER_FLAGS} ${_option}")
+      set(OPENCV_EXTRA_SHARED_LINKER_FLAGS "${OPENCV_EXTRA_SHARED_LINKER_FLAGS} ${_option}")
+      set(OPENCV_EXTRA_MODULE_LINKER_FLAGS "${OPENCV_EXTRA_MODULE_LINKER_FLAGS} ${_option}")
+    endif()
+  endif()
+endif()
+
 # combine all "extra" options
 if(NOT OPENCV_SKIP_EXTRA_COMPILER_FLAGS)
  set(CMAKE_C_FLAGS           "${CMAKE_C_FLAGS} ${OPENCV_EXTRA_FLAGS} ${OPENCV_EXTRA_C_FLAGS}")
@@ -410,6 +426,7 @@ if(MSVC)
    ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4275) # non dll-interface class 'std::exception' used as base for dll-interface class 'cv::Exception'
    ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4512) # Assignment operator could not be generated
    ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4589) # Constructor of abstract class 'cv::ORB' ignores initializer for virtual base class 'cv::Algorithm'
+    ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4819) # Symbols like delta or epsilon cannot be represented
  endif()

  if(CV_ICC AND NOT ENABLE_NOISY_WARNINGS)
@@ -243,12 +243,13 @@ if(CUDA_FOUND)
      endif()
      if(NOT _nvcc_res EQUAL 0)
        message(STATUS "Automatic detection of CUDA generation failed. Going to build for all known architectures.")
-        # TX1 (5.3) TX2 (6.2) Xavier (7.2) V100 (7.0)
+        # TX1 (5.3) TX2 (6.2) Xavier (7.2) V100 (7.0) Orin (8.7)
        ocv_filter_available_architecture(__cuda_arch_bin
            5.3
            6.2
            7.2
            7.0
+            8.7
        )
      else()
        set(__cuda_arch_bin "${_nvcc_out}")
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION ${MIN_VER_CMAKE})

 if(" ${HALIDE_ROOT_DIR}" STREQUAL " ")
  unset(HALIDE_ROOT_DIR CACHE)
@@ -1,21 +1,7 @@
-# The script detects Intel(R) Inference Engine installation
-#
-# Cache variables:
-# INF_ENGINE_RELEASE - a number reflecting IE source interface (linked with OpenVINO release)
-#
-# Detect parameters:
-# 1. Native cmake IE package:
-#    - environment variable InferenceEngine_DIR is set to location of cmake module
-# 2. Custom location:
-#    - INF_ENGINE_INCLUDE_DIRS - headers search location
-#    - INF_ENGINE_LIB_DIRS     - library search location
-# 3. OpenVINO location:
-#    - environment variable INTEL_OPENVINO_DIR is set to location of OpenVINO installation dir
-#    - INF_ENGINE_PLATFORM - part of name of library directory representing its platform
+# The script detects Intel(R) OpenVINO(TM) runtime installation
 #
 # Result:
-# INF_ENGINE_TARGET - set to name of imported library target representing InferenceEngine
-#
+# - target ocv.3rdparty.openvino

 if(NOT HAVE_CXX11)
    message(WARNING "DL Inference engine requires C++11. You can turn it on via ENABLE_CXX11=ON CMake flag.")
@@ -24,84 +10,23 @@ endif()

 # =======================

-macro(ocv_ie_find_extra_libraries find_prefix find_suffix)
-  file(GLOB libraries "${INF_ENGINE_LIB_DIRS}/${find_prefix}inference_engine*${find_suffix}")
-  foreach(full_path IN LISTS libraries)
-    get_filename_component(library "${full_path}" NAME_WE)
-    string(REPLACE "${find_prefix}" "" library "${library}")
-    if(library STREQUAL "inference_engine" OR library STREQUAL "inference_engined")
-      # skip
-    else()
-      add_library(${library} UNKNOWN IMPORTED)
-      set_target_properties(${library} PROPERTIES
-          IMPORTED_LOCATION "${full_path}")
-      list(APPEND custom_libraries ${library})
-    endif()
-  endforeach()
-endmacro()
-
-function(add_custom_ie_build _inc _lib _lib_rel _lib_dbg _msg)
-  if(NOT _inc OR NOT (_lib OR _lib_rel OR _lib_dbg))
+if(WITH_OPENVINO)
+  find_package(OpenVINO QUIET)
+  if(OpenVINO_FOUND)
+    message(STATUS "OpenVINO FOUND: ${OpenVINO_VERSION}")
+    math(EXPR ver "${OpenVINO_VERSION_MAJOR} * 1000000 + ${OpenVINO_VERSION_MINOR} * 10000 + ${OpenVINO_VERSION_PATCH} * 100")
+    ocv_add_external_target(openvino "" "openvino::runtime" "INF_ENGINE_RELEASE=${ver};HAVE_NGRAPH;HAVE_DNN_NGRAPH;HAVE_INF_ENGINE")
+    set(HAVE_OPENVINO 1)
    return()
  endif()
-  if(NOT _lib)
-    if(_lib_rel)
-      set(_lib "${_lib_rel}")
-    else()
-      set(_lib "${_lib_dbg}")
-    endif()
-  endif()
-  add_library(inference_engine UNKNOWN IMPORTED)
-  set_target_properties(inference_engine PROPERTIES
-    IMPORTED_LOCATION "${_lib}"
-    IMPORTED_IMPLIB_RELEASE "${_lib_rel}"
-    IMPORTED_IMPLIB_DEBUG "${_lib_dbg}"
-    INTERFACE_INCLUDE_DIRECTORIES "${_inc}"
-  )
-
-  set(custom_libraries "")
-  set(__prefixes "${CMAKE_FIND_LIBRARY_PREFIXES}")
-  if(NOT __prefixes)
-    set(__prefixes "_empty_")
-  endif()
-  foreach(find_prefix ${__prefixes})
-    if(find_prefix STREQUAL "_empty_")  # foreach doesn't iterate over empty elements
-      set(find_prefix "")
-    endif()
-    if(NOT DEFINED INFERENCE_ENGINE_FIND_LIBRARY_SUFFIXES)  # allow custom override
-      set(INFERENCE_ENGINE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
-      if(APPLE)
-        ocv_list_filterout(INFERENCE_ENGINE_FIND_LIBRARY_SUFFIXES "^.so$")  # skip plugins (can't be linked)
-      endif()
-    endif()
-    foreach(find_suffix ${INFERENCE_ENGINE_FIND_LIBRARY_SUFFIXES})
-      ocv_ie_find_extra_libraries("${find_prefix}" "${find_suffix}")
-    endforeach()
-    if(NOT CMAKE_FIND_LIBRARY_SUFFIXES)
-      ocv_ie_find_extra_libraries("${find_prefix}" "")
-    endif()
-  endforeach()
-
-  if(NOT INF_ENGINE_RELEASE VERSION_GREATER "2018050000")
-    find_library(INF_ENGINE_OMP_LIBRARY iomp5 PATHS "${INF_ENGINE_OMP_DIR}" NO_DEFAULT_PATH)
-    if(NOT INF_ENGINE_OMP_LIBRARY)
-      message(WARNING "OpenMP for IE have not been found. Set INF_ENGINE_OMP_DIR variable if you experience build errors.")
-    endif()
-  endif()
-  if(EXISTS "${INF_ENGINE_OMP_LIBRARY}")
-    set_target_properties(inference_engine PROPERTIES IMPORTED_LINK_INTERFACE_LIBRARIES "${INF_ENGINE_OMP_LIBRARY}")
-  endif()
-  set(INF_ENGINE_VERSION "Unknown" CACHE STRING "")
-  set(INF_ENGINE_TARGET "inference_engine;${custom_libraries}" PARENT_SCOPE)
-  message(STATUS "Detected InferenceEngine: ${_msg}")
-endfunction()
+endif()

 # ======================

 find_package(InferenceEngine QUIET)
 if(InferenceEngine_FOUND)
  set(INF_ENGINE_TARGET ${InferenceEngine_LIBRARIES})
-  set(INF_ENGINE_VERSION "${InferenceEngine_VERSION}" CACHE STRING "")
+  set(INF_ENGINE_VERSION "${InferenceEngine_VERSION}")
  message(STATUS "Detected InferenceEngine: cmake package (${InferenceEngine_VERSION})")
 endif()

@@ -119,47 +44,19 @@ elseif(DEFINED INF_ENGINE_RELEASE)
 endif()
 set(INF_ENGINE_RELEASE "${INF_ENGINE_RELEASE_INIT}" CACHE STRING "Force IE version, should be in form YYYYAABBCC (e.g. 2020.1.0.2 -> 2020010002)")

-if(NOT INF_ENGINE_TARGET AND INF_ENGINE_LIB_DIRS AND INF_ENGINE_INCLUDE_DIRS)
-  find_path(ie_custom_inc "inference_engine.hpp" PATHS "${INF_ENGINE_INCLUDE_DIRS}" NO_DEFAULT_PATH)
-  if(CMAKE_BUILD_TYPE STREQUAL "Debug")
-    find_library(ie_custom_lib_dbg "inference_engined" PATHS "${INF_ENGINE_LIB_DIRS}" NO_DEFAULT_PATH)  # Win32 and MacOSX
-  endif()
-  find_library(ie_custom_lib "inference_engine" PATHS "${INF_ENGINE_LIB_DIRS}" NO_DEFAULT_PATH)
-  find_library(ie_custom_lib_rel "inference_engine" PATHS "${INF_ENGINE_LIB_DIRS}/Release" NO_DEFAULT_PATH)
-  find_library(ie_custom_lib_dbg "inference_engine" PATHS "${INF_ENGINE_LIB_DIRS}/Debug" NO_DEFAULT_PATH)
-  add_custom_ie_build("${ie_custom_inc}" "${ie_custom_lib}" "${ie_custom_lib_rel}" "${ie_custom_lib_dbg}" "INF_ENGINE_{INCLUDE,LIB}_DIRS")
-endif()
-
-set(_loc "$ENV{INTEL_OPENVINO_DIR}")
-if(NOT _loc AND DEFINED ENV{INTEL_CVSDK_DIR})
-  set(_loc "$ENV{INTEL_CVSDK_DIR}")  # OpenVINO 2018.x
-endif()
-if(NOT INF_ENGINE_TARGET AND _loc)
-  if(NOT INF_ENGINE_RELEASE VERSION_GREATER "2018050000")
-    set(INF_ENGINE_PLATFORM_DEFAULT "ubuntu_16.04")
-  else()
-    set(INF_ENGINE_PLATFORM_DEFAULT "")
-  endif()
-  set(INF_ENGINE_PLATFORM "${INF_ENGINE_PLATFORM_DEFAULT}" CACHE STRING "InferenceEngine platform (library dir)")
-  find_path(ie_custom_env_inc "inference_engine.hpp" PATHS "${_loc}/deployment_tools/inference_engine/include" NO_DEFAULT_PATH)
-  if(CMAKE_BUILD_TYPE STREQUAL "Debug")
-    find_library(ie_custom_env_lib_dbg "inference_engined" PATHS "${_loc}/deployment_tools/inference_engine/lib/${INF_ENGINE_PLATFORM}/intel64" NO_DEFAULT_PATH)
-  endif()
-  find_library(ie_custom_env_lib "inference_engine" PATHS "${_loc}/deployment_tools/inference_engine/lib/${INF_ENGINE_PLATFORM}/intel64" NO_DEFAULT_PATH)
-  find_library(ie_custom_env_lib_rel "inference_engine" PATHS "${_loc}/deployment_tools/inference_engine/lib/intel64/Release" NO_DEFAULT_PATH)
-  find_library(ie_custom_env_lib_dbg "inference_engine" PATHS "${_loc}/deployment_tools/inference_engine/lib/intel64/Debug" NO_DEFAULT_PATH)
-  add_custom_ie_build("${ie_custom_env_inc}" "${ie_custom_env_lib}" "${ie_custom_env_lib_rel}" "${ie_custom_env_lib_dbg}" "OpenVINO (${_loc})")
-endif()
+set(tgts)
+set(defs)

 # Add more features to the target
-
 if(INF_ENGINE_TARGET)
  set_target_properties(${INF_ENGINE_TARGET} PROPERTIES
      INTERFACE_COMPILE_DEFINITIONS "HAVE_INF_ENGINE=1;INF_ENGINE_RELEASE=${INF_ENGINE_RELEASE}"
  )
+  list(APPEND tgts ${INF_ENGINE_TARGET})
+  list(APPEND defs "INF_ENGINE_RELEASE=${INF_ENGINE_RELEASE}" "HAVE_INF_ENGINE")
 endif()

-if(WITH_NGRAPH)
+if(WITH_NGRAPH OR NOT DEFINED WITH_NGRAPH)
  find_package(ngraph QUIET)
  if(ngraph_FOUND)
    ocv_assert(TARGET ngraph::ngraph)
@@ -168,5 +65,9 @@ if(WITH_NGRAPH)
    endif()
    message(STATUS "Detected ngraph: cmake package (${ngraph_VERSION})")
    set(HAVE_NGRAPH ON)
+    list(APPEND tgts ngraph::ngraph)
+    list(APPEND defs "HAVE_NGRAPH" "HAVE_DNN_NGRAPH")
  endif()
 endif()
+
+ocv_add_external_target(openvino "" "${tgts}" "${defs}")
@@ -19,7 +19,7 @@
 #   - "tbb" target exists and added to OPENCV_LINKER_LIBS

 function(ocv_tbb_cmake_guess _found)
-    find_package(TBB QUIET COMPONENTS tbb PATHS "$ENV{TBBROOT}/cmake")
+    find_package(TBB QUIET COMPONENTS tbb PATHS "$ENV{TBBROOT}/cmake" "$ENV{TBBROOT}/lib/cmake/tbb")
    if(TBB_FOUND)
      if(NOT TARGET TBB::tbb)
        message(WARNING "No TBB::tbb target found!")
@@ -28,11 +28,11 @@ function(ocv_tbb_cmake_guess _found)
      get_target_property(_lib TBB::tbb IMPORTED_LOCATION_RELEASE)
      message(STATUS "Found TBB (cmake): ${_lib}")
      get_target_property(_inc TBB::tbb INTERFACE_INCLUDE_DIRECTORIES)
-      ocv_tbb_read_version("${_inc}")
      add_library(tbb INTERFACE IMPORTED)
      set_target_properties(tbb PROPERTIES
        INTERFACE_LINK_LIBRARIES TBB::tbb
      )
+      ocv_tbb_read_version("${_inc}" tbb)
      set(${_found} TRUE PARENT_SCOPE)
    endif()
 endfunction()
@@ -66,7 +66,6 @@ function(ocv_tbb_env_guess _found)
  find_library(TBB_ENV_LIB_DEBUG NAMES "tbb_debug")
  if (TBB_ENV_INCLUDE AND (TBB_ENV_LIB OR TBB_ENV_LIB_DEBUG))
    ocv_tbb_env_verify()
-    ocv_tbb_read_version("${TBB_ENV_INCLUDE}")
    add_library(tbb UNKNOWN IMPORTED)
    set_target_properties(tbb PROPERTIES
      IMPORTED_LOCATION "${TBB_ENV_LIB}"
@@ -82,12 +81,14 @@ function(ocv_tbb_env_guess _found)
      get_filename_component(_dir "${TBB_ENV_LIB}" DIRECTORY)
      set_target_properties(tbb PROPERTIES INTERFACE_LINK_LIBRARIES "-L${_dir}")
    endif()
+    ocv_tbb_read_version("${TBB_ENV_INCLUDE}" tbb)
    message(STATUS "Found TBB (env): ${TBB_ENV_LIB}")
    set(${_found} TRUE PARENT_SCOPE)
  endif()
 endfunction()

-function(ocv_tbb_read_version _path)
+function(ocv_tbb_read_version _path _tgt)
+  find_file(TBB_VER_FILE oneapi/tbb/version.h "${_path}" NO_DEFAULT_PATH CMAKE_FIND_ROOT_PATH_BOTH)
  find_file(TBB_VER_FILE tbb/tbb_stddef.h "${_path}" NO_DEFAULT_PATH CMAKE_FIND_ROOT_PATH_BOTH)
  ocv_parse_header("${TBB_VER_FILE}" TBB_VERSION_LINES TBB_VERSION_MAJOR TBB_VERSION_MINOR TBB_INTERFACE_VERSION CACHE)
 endfunction()
@@ -118,16 +118,10 @@ if(MKL_USE_SINGLE_DYNAMIC_LIBRARY AND NOT (MKL_VERSION_STR VERSION_LESS "10.3.0"

 elseif(NOT (MKL_VERSION_STR VERSION_LESS "11.3.0"))

-  foreach(MKL_ARCH ${MKL_ARCH_LIST})
-    list(APPEND mkl_lib_find_paths
-      ${MKL_ROOT_DIR}/../tbb/lib/${MKL_ARCH}
-    )
-  endforeach()
-
  set(mkl_lib_list "mkl_intel_${MKL_ARCH_SUFFIX}")

  if(MKL_WITH_TBB)
-    list(APPEND mkl_lib_list mkl_tbb_thread tbb)
+    list(APPEND mkl_lib_list mkl_tbb_thread)
  elseif(MKL_WITH_OPENMP)
    if(MSVC)
      list(APPEND mkl_lib_list mkl_intel_thread libiomp5md)
@@ -155,6 +149,7 @@ if(NOT MKL_LIBRARIES)
    endif()
    list(APPEND MKL_LIBRARIES ${${lib_var_name}})
  endforeach()
+  list(APPEND MKL_LIBRARIES ${OPENCV_EXTRA_MKL_LIBRARIES})
 endif()

 message(STATUS "Found MKL ${MKL_VERSION_STR} at: ${MKL_ROOT_DIR}")
@@ -866,7 +866,10 @@ macro(ocv_check_modules define)
      foreach(flag ${${define}_LDFLAGS})
        if(flag MATCHES "^-L(.*)")
          list(APPEND _libs_paths ${CMAKE_MATCH_1})
-        elseif(IS_ABSOLUTE "${flag}")
+        elseif(IS_ABSOLUTE "${flag}"
+            OR flag STREQUAL "-lstdc++"
+            OR flag STREQUAL "-latomic"
+        )
          list(APPEND _libs "${flag}")
        elseif(flag MATCHES "^-l(.*)")
          set(_lib "${CMAKE_MATCH_1}")
@@ -1580,6 +1583,60 @@ function(ocv_add_library target)
 endfunction()


+function(ocv_add_external_target name inc link def)
+  if(BUILD_SHARED_LIBS AND link)
+    set(imp IMPORTED)
+  endif()
+  add_library(ocv.3rdparty.${name} INTERFACE ${imp})
+  if(def)
+    if(NOT (CMAKE_VERSION VERSION_LESS "3.11.0"))  # https://gitlab.kitware.com/cmake/cmake/-/merge_requests/1264 : eliminates "Cannot specify compile definitions for imported target" error message
+      target_compile_definitions(ocv.3rdparty.${name} INTERFACE "${def}")
+    else()
+      set_target_properties(ocv.3rdparty.${name} PROPERTIES INTERFACE_COMPILE_DEFINITIONS "${def}")
+    endif()
+  endif()
+  if(inc)
+    if(NOT (CMAKE_VERSION VERSION_LESS "3.11.0"))  # https://gitlab.kitware.com/cmake/cmake/-/merge_requests/1264 : eliminates "Cannot specify compile definitions for imported target" error message
+      target_include_directories(ocv.3rdparty.${name} SYSTEM INTERFACE "$<BUILD_INTERFACE:${inc}>")
+    else()
+      set_target_properties(ocv.3rdparty.${name} PROPERTIES
+          INTERFACE_INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${inc}>"
+          INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${inc}>"
+      )
+    endif()
+  endif()
+  if(link)
+    # When cmake version is greater than or equal to 3.11, INTERFACE_LINK_LIBRARIES no longer applies to interface library
+    # See https://github.com/opencv/opencv/pull/18658
+    if(CMAKE_VERSION VERSION_LESS 3.11)
+      set_target_properties(ocv.3rdparty.${name} PROPERTIES
+        INTERFACE_LINK_LIBRARIES "${link}")
+    else()
+      target_link_libraries(ocv.3rdparty.${name} INTERFACE ${link})
+    endif()
+  endif()
+  # to install used target only upgrade CMake
+  if(NOT BUILD_SHARED_LIBS
+      AND CMAKE_VERSION VERSION_LESS "3.13.0"  # https://gitlab.kitware.com/cmake/cmake/-/merge_requests/2152
+  )
+    install(TARGETS ocv.3rdparty.${name} EXPORT OpenCVModules)
+  endif()
+endfunction()
+
+
+# Returns the first non-interface target
+function(ocv_get_imported_target imported interface)
+  set(__result "${interface}")
+  get_target_property(__type "${__result}" TYPE)
+  if(__type STREQUAL "INTERFACE_LIBRARY")
+    get_target_property(__libs "${__result}" INTERFACE_LINK_LIBRARIES)
+    list(GET __libs 0 __interface)
+    ocv_get_imported_target(__result "${__interface}")
+  endif()
+  set(${imported} "${__result}" PARENT_SCOPE)
+endfunction()
+
+
 macro(ocv_get_libname var_name)
  get_filename_component(__libname "${ARGN}" NAME)
  # libopencv_core.so.3.3 -> opencv_core
@@ -0,0 +1,24 @@
+#include <stdio.h>
+
+#if defined __GNUC__ && (defined __arm__ || defined __aarch64__)
+#include "arm_neon.h"
+int test()
+{
+    const unsigned int src[] = { 0, 0, 0, 0 };
+    unsigned int dst[4];
+    uint32x4_t v_src = *(uint32x4_t*)src;
+    uint8x16_t v_m0 = *(uint8x16_t*)src;
+    uint8x16_t v_m1 = *(uint8x16_t*)src;
+    uint32x4_t v_dst = vdotq_u32(v_src, v_m0, v_m1);
+    *(uint32x4_t*)dst = v_dst;
+    return (int)dst[0];
+}
+#else
+#error "DOTPROD is not supported"
+#endif
+
+int main()
+{
+  printf("%d\n", test());
+  return 0;
+}
@@ -41,7 +41,7 @@
 <script src="utils.js" type="text/javascript"></script>
 <script id="codeSnippet" type="text/code-snippet">
 let src = cv.imread('canvasInput');
-let dst = cv.Mat.zeros(src.cols, src.rows, cv.CV_8UC3);
+let dst = cv.Mat.zeros(src.rows, src.cols, cv.CV_8UC3);
 cv.cvtColor(src, src, cv.COLOR_RGBA2GRAY, 0);
 cv.threshold(src, src, 120, 200, cv.THRESH_BINARY);
 let contours = new cv.MatVector();
@@ -147,7 +147,7 @@ if (dataset === 'COCO') {
                   ["Neck", "LShoulder"], ["RShoulder", "RElbow"],
                   ["RElbow", "RWrist"], ["LShoulder", "LElbow"],
                   ["LElbow", "LWrist"], ["Nose", "REye"],
-                   ["REye", "REar"], ["Neck", "LEye"],
+                   ["REye", "REar"], ["Nose", "LEye"],
                   ["LEye", "LEar"], ["Neck", "MidHip"],
                   ["MidHip", "RHip"], ["RHip", "RKnee"],
                   ["RKnee", "RAnkle"], ["RAnkle", "RBigToe"],
@@ -15,7 +15,7 @@ We will see each one of them.

 ### 1. Sobel and Scharr Derivatives

-Sobel operators is a joint Gausssian smoothing plus differentiation operation, so it is more
+Sobel operators is a joint Gaussian smoothing plus differentiation operation, so it is more
 resistant to noise. You can specify the direction of derivatives to be taken, vertical or horizontal
 (by the arguments, yorder and xorder respectively). You can also specify the size of kernel by the
 argument ksize. If ksize = -1, a 3x3 Scharr filter is used which gives better results than 3x3 Sobel
@@ -97,4 +97,4 @@ Try it
 <iframe src="../../js_gradients_absSobel.html" width="100%"
        onload="this.style.height=this.contentDocument.body.scrollHeight +'px';">
 </iframe>
-\endhtmlonly
+\endhtmlonly
@@ -52,7 +52,7 @@ Try it

 ### 2. Dilation

-It is just opposite of erosion. Here, a pixel element is '1' if atleast one pixel under the kernel
+It is just opposite of erosion. Here, a pixel element is '1' if at least one pixel under the kernel
 is '1'. So it increases the white region in the image or size of foreground object increases.
 Normally, in cases like noise removal, erosion is followed by dilation. Because, erosion removes
 white noises, but it also shrinks our object. So we dilate it. Since noise is gone, they won't come
@@ -223,7 +223,7 @@ Before the example, is worth consider first how files are handled in emscripten

 These C++ sources use standard APIs to access the filesystem and the implementation often ends up in system calls that read a file in the hard drive. Since JavaScript applications in the browser don't have access to the local filesystem, [emscripten emulates a standard filesystem](https://emscripten.org/docs/api_reference/Filesystem-API.html) so compiled C++ code works out of the box.

-In the browser, this filesystem is emulated in memory while in Node.js there's also the possibility of using the local filesystem directly. This is often preferable since there's no need of copy file's content in memory. This section is explains how to do do just that, this is, configuring emscripten so files are accessed directly from our local filesystem and relative paths match files relative to the current local directory as expected.
+In the browser, this filesystem is emulated in memory while in Node.js there's also the possibility of using the local filesystem directly. This is often preferable since there's no need of copy file's content in memory. This section explains how to do just that, this is, configuring emscripten so files are accessed directly from our local filesystem and relative paths match files relative to the current local directory as expected.

 ### The example ###

@@ -232,7 +232,7 @@ The following is an adaptation of @ref tutorial_js_face_detection.
@code{.js}
 const { Canvas, createCanvas, Image, ImageData, loadImage } = require('canvas');
 const { JSDOM } = require('jsdom');
-const { writeFileSync, readFileSync } = require('fs');
+const { writeFileSync, existsSync, mkdirSync } = require('fs');

 (async () => {
  await loadOpenCV();
@@ -122,11 +122,14 @@ imgElement.onload = function() {
  mat.delete();
 };

-function onOpenCvReady() {
-  document.getElementById('status').innerHTML = 'OpenCV.js is ready.';
-}
+var Module = {
+  // https://emscripten.org/docs/api_reference/module.html#Module.onRuntimeInitialized
+  onRuntimeInitialized() {
+    document.getElementById('status').innerHTML = 'OpenCV.js is ready.';
+  }
+};
 </script>
-<script async src="opencv.js" onload="onOpenCvReady();" type="text/javascript"></script>
+<script async src="opencv.js" type="text/javascript"></script>
 </body>
 </html>
@endcode
@@ -8,14 +8,18 @@
  url = {https://www.doc.ic.ac.uk/~ajd/Publications/alcantarilla_etal_eccv2012.pdf}
 }
@article{ANB13,
-  author = {Alcantarilla, Pablo F and Nuevo, Jes{\'u}s and Bartoli, Adrien},
+  author = {Pablo Fern{\'{a}}ndez Alcantarilla and Jes{\'{u}}s Nuevo and Adrien Bartoli},
+  editor = {Tilo Burghardt and Dima Damen and Walterio W. Mayol{-}Cuevas and Majid Mirmehdi},
  title = {Fast Explicit Diffusion for Accelerated Features in Nonlinear Scale Spaces},
-  year = {2011},
-  pages = {1281--1298},
-  journal = {Trans. Pattern Anal. Machine Intell},
-  volume = {34},
-  number = {7},
-  url = {http://www.bmva.org/bmvc/2013/Papers/paper0013/paper0013.pdf}
+  booktitle = {British Machine Vision Conference, {BMVC} 2013, Bristol, UK, September 9-13, 2013},
+  pages = {13.1--13.11},
+  publisher = {{BMVA} Press},
+  year = {2013},
+  url = {https://doi.org/10.5244/C.27.13},
+  doi = {10.5244/C.27.13},
+  timestamp = {Sat, 09 Apr 2022 12:44:13 +0200},
+  biburl = {https://dblp.org/rec/conf/bmvc/AlcantarillaNB13.bib},
+  bibsource = {dblp computer science bibliography, https://dblp.org}
 }
@inproceedings{Andreff99,
  author = {Andreff, Nicolas and Horaud, Radu and Espiau, Bernard},
@@ -543,7 +547,7 @@
  title = {Multiple view geometry in computer vision},
  year = {2003},
  publisher = {Cambridge university press},
-  url = {http://cds.cern.ch/record/1598612/files/0521540518_TOC.pdf}
+  url = {https://www.robots.ox.ac.uk/~vgg/hzbook/}
 }
@article{Horaud95,
  author = {Horaud, Radu and Dornaika, Fadi},
@@ -745,10 +749,17 @@
  isbn = {0387008934},
  publisher = {Springer}
 }
-@article{Malis,
-  author = {Malis, Ezio and Vargas, Manuel and others},
-  title = {Deeper understanding of the homography decomposition for vision-based control},
-  year = {2007}
+@article{Malis2007,
+  author = {Malis, Ezio and Vargas, Manuel},
+  title = {{Deeper understanding of the homography decomposition for vision-based control}},
+  year = {2007},
+  url = {https://hal.inria.fr/inria-00174036},
+  type = {Research Report},
+  number = {RR-6303},
+  pages = {90},
+  institution = {{INRIA}},
+  keywords = {Visual servoing ; planar objects ; homography ; decomposition ; camera calibration errors ; structure from motion ; Euclidean},
+  pdf = {https://hal.inria.fr/inria-00174036v3/file/RR-6303.pdf},
 }
@article{Marchand16,
  author = {Marchand, Eric and Uchiyama, Hideaki and Spindler, Fabien},
@@ -905,7 +916,8 @@
  author = {Szeliski, Richard},
  title = {Computer vision: algorithms and applications},
  year = {2010},
-  publisher = {Springer}
+  publisher = {Springer},
+  url = {https://szeliski.org/Book/}
 }
@article{Rafael12,
  author = {von Gioi, Rafael Grompone and Jakubowicz, J{\'e}r{\'e}mie and Morel, Jean-Michel and Randall, Gregory},
@@ -1292,3 +1304,20 @@
  publisher={IEEE},
  doi = {10.1109/TPAMI.2021.3055337}
 }
+@article{Kannala2006,
+  author = {Kannala, Juho and Brandt, Sami},
+  year = {2006},
+  month = {09},
+  pages = {1335-40},
+  title = {A Generic Camera Model and Calibration Method for Conventional, Wide-Angle, and Fish-Eye Lenses},
+  volume = {28},
+  journal = {IEEE transactions on pattern analysis and machine intelligence},
+  doi = {10.1109/TPAMI.2006.153}
+}
+@article{Buades2005DenoisingIS,
+  title={Denoising image sequences does not require motion estimation},
+  author={Antoni Buades and Bartomeu Coll and Jean-Michel Morel},
+  journal={IEEE Conference on Advanced Video and Signal Based Surveillance, 2005.},
+  year={2005},
+  pages={70-74}
+}
@@ -127,7 +127,7 @@ for fname in images:
        objpoints.append(objp)

        corners2 = cv.cornerSubPix(gray,corners, (11,11), (-1,-1), criteria)
-        imgpoints.append(corners)
+        imgpoints.append(corners2)

        # Draw and display the corners
        cv.drawChessboardCorners(img, (7,6), corners2, ret)
@@ -41,8 +41,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-imgL = cv.imread('tsukuba_l.png',0)
-imgR = cv.imread('tsukuba_r.png',0)
+imgL = cv.imread('tsukuba_l.png', cv.IMREAD_GRAYSCALE)
+imgR = cv.imread('tsukuba_r.png', cv.IMREAD_GRAYSCALE)

 stereo = cv.StereoBM_create(numDisparities=16, blockSize=15)
 disparity = stereo.compute(imgL,imgR)
@@ -76,8 +76,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img1 = cv.imread('myleft.jpg',0)  #queryimage # left image
-img2 = cv.imread('myright.jpg',0) #trainimage # right image
+img1 = cv.imread('myleft.jpg', cv.IMREAD_GRAYSCALE)  #queryimage # left image
+img2 = cv.imread('myright.jpg', cv.IMREAD_GRAYSCALE) #trainimage # right image

 sift = cv.SIFT_create()

@@ -25,6 +25,7 @@ Let's load a color image first:
 >>> import cv2 as cv

 >>> img = cv.imread('messi5.jpg')
+>>> assert img is not None, "file could not be read, check with os.path.exists()"
@endcode
 You can access a pixel value by its row and column coordinates. For BGR image, it returns an array
 of Blue, Green, Red values. For grayscale image, just corresponding intensity is returned.
@@ -173,6 +174,7 @@ from matplotlib import pyplot as plt
 BLUE = [255,0,0]

 img1 = cv.imread('opencv-logo.png')
+assert img1 is not None, "file could not be read, check with os.path.exists()"

 replicate = cv.copyMakeBorder(img1,10,10,10,10,cv.BORDER_REPLICATE)
 reflect = cv.copyMakeBorder(img1,10,10,10,10,cv.BORDER_REFLECT)
@@ -50,6 +50,8 @@ Here \f$\gamma\f$ is taken as zero.
@code{.py}
 img1 = cv.imread('ml.png')
 img2 = cv.imread('opencv-logo.png')
+assert img1 is not None, "file could not be read, check with os.path.exists()"
+assert img2 is not None, "file could not be read, check with os.path.exists()"

 dst = cv.addWeighted(img1,0.7,img2,0.3,0)

@@ -76,6 +78,8 @@ bitwise operations as shown below:
 # Load two images
 img1 = cv.imread('messi5.jpg')
 img2 = cv.imread('opencv-logo-white.png')
+assert img1 is not None, "file could not be read, check with os.path.exists()"
+assert img2 is not None, "file could not be read, check with os.path.exists()"

 # I want to put logo on top-left corner, So I create a ROI
 rows,cols,channels = img2.shape
@@ -14,7 +14,7 @@ So in this chapter, you will learn:
 Apart from OpenCV, Python also provides a module **time** which is helpful in measuring the time of
 execution. Another module **profile** helps to get a detailed report on the code, like how much time
 each function in the code took, how many times the function was called, etc. But, if you are using
-IPython, all these features are integrated in an user-friendly manner. We will see some important
+IPython, all these features are integrated in a user-friendly manner. We will see some important
 ones, and for more details, check links in the **Additional Resources** section.

 Measuring Performance with OpenCV
@@ -37,6 +37,7 @@ of odd sizes ranging from 5 to 49. (Don't worry about what the result will look
 goal):
@code{.py}
 img1 = cv.imread('messi5.jpg')
+assert img1 is not None, "file could not be read, check with os.path.exists()"

 e1 = cv.getTickCount()
 for i in range(5,49,2):
@@ -63,7 +63,7 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('simple.jpg',0)
+img = cv.imread('simple.jpg', cv.IMREAD_GRAYSCALE)

 # Initiate FAST detector
 star = cv.xfeatures2d.StarDetector_create()
@@ -98,7 +98,7 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('blox.jpg',0) # `<opencv_root>/samples/data/blox.jpg`
+img = cv.imread('blox.jpg', cv.IMREAD_GRAYSCALE) # `<opencv_root>/samples/data/blox.jpg`

 # Initiate FAST object with default values
 fast = cv.FastFeatureDetector_create()
@@ -18,7 +18,7 @@ is sufficient to find the object exactly on the trainImage.

 For that, we can use a function from calib3d module, ie **cv.findHomography()**. If we pass the set
 of points from both the images, it will find the perspective transformation of that object. Then we
-can use **cv.perspectiveTransform()** to find the object. It needs atleast four correct points to
+can use **cv.perspectiveTransform()** to find the object. It needs at least four correct points to
 find the transformation.

 We have seen that there can be some possible errors while matching which may affect the result. To
@@ -40,8 +40,8 @@ from matplotlib import pyplot as plt

 MIN_MATCH_COUNT = 10

-img1 = cv.imread('box.png',0)          # queryImage
-img2 = cv.imread('box_in_scene.png',0) # trainImage
+img1 = cv.imread('box.png', cv.IMREAD_GRAYSCALE)          # queryImage
+img2 = cv.imread('box_in_scene.png', cv.IMREAD_GRAYSCALE) # trainImage

 # Initiate SIFT detector
 sift = cv.SIFT_create()
@@ -64,7 +64,7 @@ for m,n in matches:
    if m.distance < 0.7*n.distance:
        good.append(m)
@endcode
-Now we set a condition that atleast 10 matches (defined by MIN_MATCH_COUNT) are to be there to
+Now we set a condition that at least 10 matches (defined by MIN_MATCH_COUNT) are to be there to
 find the object. Otherwise simply show a message saying not enough matches are present.

 If enough matches are found, we extract the locations of matched keypoints in both the images. They
@@ -67,7 +67,7 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('simple.jpg',0)
+img = cv.imread('simple.jpg', cv.IMREAD_GRAYSCALE)

 # Initiate ORB detector
 orb = cv.ORB_create()
@@ -76,7 +76,7 @@ and descriptors.
 First we will see a simple demo on how to find SURF keypoints and descriptors and draw it. All
 examples are shown in Python terminal since it is just same as SIFT only.
@code{.py}
->>> img = cv.imread('fly.png',0)
+>>> img = cv.imread('fly.png', cv.IMREAD_GRAYSCALE)

 # Create SURF object. You can specify params here or later.
 # Here I set Hessian Threshold to 400
@@ -83,7 +83,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('messi5.jpg',0)
+img = cv.imread('messi5.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 edges = cv.Canny(img,100,200)

 plt.subplot(121),plt.imshow(img,cmap = 'gray')
@@ -24,7 +24,8 @@ The function **cv.moments()** gives a dictionary of all moment values calculated
 import numpy as np
 import cv2 as cv

-img = cv.imread('star.jpg',0)
+img = cv.imread('star.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 ret,thresh = cv.threshold(img,127,255,0)
 im2,contours,hierarchy = cv.findContours(thresh, 1, 2)

@@ -29,6 +29,7 @@ import numpy as np
 import cv2 as cv

 im = cv.imread('test.jpg')
+assert im is not None, "file could not be read, check with os.path.exists()"
 imgray = cv.cvtColor(im, cv.COLOR_BGR2GRAY)
 ret, thresh = cv.threshold(imgray, 127, 255, 0)
 im2, contours, hierarchy = cv.findContours(thresh, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE)
@@ -41,6 +41,7 @@ import cv2 as cv
 import numpy as np

 img = cv.imread('star.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"
 img_gray = cv.cvtColor(img,cv.COLOR_BGR2GRAY)
 ret,thresh = cv.threshold(img_gray, 127, 255,0)
 im2,contours,hierarchy = cv.findContours(thresh,2,1)
@@ -92,8 +93,10 @@ docs.
 import cv2 as cv
 import numpy as np

-img1 = cv.imread('star.jpg',0)
-img2 = cv.imread('star2.jpg',0)
+img1 = cv.imread('star.jpg', cv.IMREAD_GRAYSCALE)
+img2 = cv.imread('star2.jpg', cv.IMREAD_GRAYSCALE)
+assert img1 is not None, "file could not be read, check with os.path.exists()"
+assert img2 is not None, "file could not be read, check with os.path.exists()"

 ret, thresh = cv.threshold(img1, 127, 255,0)
 ret, thresh2 = cv.threshold(img2, 127, 255,0)
@@ -29,6 +29,7 @@ import cv2 as cv
 from matplotlib import pyplot as plt

 img = cv.imread('opencv_logo.png')
+assert img is not None, "file could not be read, check with os.path.exists()"

 kernel = np.ones((5,5),np.float32)/25
 dst = cv.filter2D(img,-1,kernel)
@@ -70,6 +71,7 @@ import numpy as np
 from matplotlib import pyplot as plt

 img = cv.imread('opencv-logo-white.png')
+assert img is not None, "file could not be read, check with os.path.exists()"

 blur = cv.blur(img,(5,5))

@@ -28,6 +28,7 @@ import numpy as np
 import cv2 as cv

 img = cv.imread('messi5.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"

 res = cv.resize(img,None,fx=2, fy=2, interpolation = cv.INTER_CUBIC)

@@ -49,7 +50,8 @@ function. See the below example for a shift of (100,50):
 import numpy as np
 import cv2 as cv

-img = cv.imread('messi5.jpg',0)
+img = cv.imread('messi5.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 rows,cols = img.shape

 M = np.float32([[1,0,100],[0,1,50]])
@@ -87,7 +89,8 @@ where:
 To find this transformation matrix, OpenCV provides a function, **cv.getRotationMatrix2D**. Check out the
 below example which rotates the image by 90 degree with respect to center without any scaling.
@code{.py}
-img = cv.imread('messi5.jpg',0)
+img = cv.imread('messi5.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 rows,cols = img.shape

 # cols-1 and rows-1 are the coordinate limits.
@@ -108,6 +111,7 @@ which is to be passed to **cv.warpAffine**.
 Check the below example, and also look at the points I selected (which are marked in green color):
@code{.py}
 img = cv.imread('drawing.png')
+assert img is not None, "file could not be read, check with os.path.exists()"
 rows,cols,ch = img.shape

 pts1 = np.float32([[50,50],[200,50],[50,200]])
@@ -137,6 +141,7 @@ matrix.
 See the code below:
@code{.py}
 img = cv.imread('sudoku.png')
+assert img is not None, "file could not be read, check with os.path.exists()"
 rows,cols,ch = img.shape

 pts1 = np.float32([[56,65],[368,52],[28,387],[389,390]])
@@ -93,6 +93,7 @@ import cv2 as cv
 from matplotlib import pyplot as plt

 img = cv.imread('messi5.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"
 mask = np.zeros(img.shape[:2],np.uint8)

 bgdModel = np.zeros((1,65),np.float64)
@@ -122,7 +123,8 @@ remaining background with gray. Then loaded that mask image in OpenCV, edited or
 got with corresponding values in newly added mask image. Check the code below:*
@code{.py}
 # newmask is the mask image I manually labelled
-newmask = cv.imread('newmask.png',0)
+newmask = cv.imread('newmask.png', cv.IMREAD_GRAYSCALE)
+assert newmask is not None, "file could not be read, check with os.path.exists()"

 # wherever it is marked white (sure foreground), change mask=1
 # wherever it is marked black (sure background), change mask=0
@@ -17,7 +17,7 @@ We will see each one of them.

 ### 1. Sobel and Scharr Derivatives

-Sobel operators is a joint Gausssian smoothing plus differentiation operation, so it is more
+Sobel operators is a joint Gaussian smoothing plus differentiation operation, so it is more
 resistant to noise. You can specify the direction of derivatives to be taken, vertical or horizontal
 (by the arguments, yorder and xorder respectively). You can also specify the size of kernel by the
 argument ksize. If ksize = -1, a 3x3 Scharr filter is used which gives better results than 3x3 Sobel
@@ -42,7 +42,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('dave.jpg',0)
+img = cv.imread('dave.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"

 laplacian = cv.Laplacian(img,cv.CV_64F)
 sobelx = cv.Sobel(img,cv.CV_64F,1,0,ksize=5)
@@ -79,7 +80,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('box.png',0)
+img = cv.imread('box.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"

 # Output dtype = cv.CV_8U
 sobelx8u = cv.Sobel(img,cv.CV_8U,1,0,ksize=5)
@@ -38,6 +38,7 @@ import numpy as np
 import cv2 as cv

 img = cv.imread('home.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"
 hsv = cv.cvtColor(img,cv.COLOR_BGR2HSV)

 hist = cv.calcHist([hsv], [0, 1], None, [180, 256], [0, 180, 0, 256])
@@ -55,6 +56,7 @@ import cv2 as cv
 from matplotlib import pyplot as plt

 img = cv.imread('home.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"
 hsv = cv.cvtColor(img,cv.COLOR_BGR2HSV)

 hist, xbins, ybins = np.histogram2d(h.ravel(),s.ravel(),[180,256],[[0,180],[0,256]])
@@ -89,6 +91,7 @@ import cv2 as cv
 from matplotlib import pyplot as plt

 img = cv.imread('home.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"
 hsv = cv.cvtColor(img,cv.COLOR_BGR2HSV)
 hist = cv.calcHist( [hsv], [0, 1], None, [180, 256], [0, 180, 0, 256] )

@@ -38,10 +38,12 @@ import cv2 as cvfrom matplotlib import pyplot as plt

 #roi is the object or region of object we need to find
 roi = cv.imread('rose_red.png')
+assert roi is not None, "file could not be read, check with os.path.exists()"
 hsv = cv.cvtColor(roi,cv.COLOR_BGR2HSV)

 #target is the image we search in
 target = cv.imread('rose.png')
+assert target is not None, "file could not be read, check with os.path.exists()"
 hsvt = cv.cvtColor(target,cv.COLOR_BGR2HSV)

 # Find the histograms using calcHist. Can be done with np.histogram2d also
@@ -85,9 +87,11 @@ import numpy as np
 import cv2 as cv

 roi = cv.imread('rose_red.png')
+assert roi is not None, "file could not be read, check with os.path.exists()"
 hsv = cv.cvtColor(roi,cv.COLOR_BGR2HSV)

 target = cv.imread('rose.png')
+assert target is not None, "file could not be read, check with os.path.exists()"
 hsvt = cv.cvtColor(target,cv.COLOR_BGR2HSV)

 # calculating object histogram
@@ -77,7 +77,8 @@ and its parameters :
 So let's start with a sample image. Simply load an image in grayscale mode and find its full
 histogram.
@code{.py}
-img = cv.imread('home.jpg',0)
+img = cv.imread('home.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 hist = cv.calcHist([img],[0],None,[256],[0,256])
@endcode
 hist is a 256x1 array, each value corresponds to number of pixels in that image with its
@@ -121,7 +122,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('home.jpg',0)
+img = cv.imread('home.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 plt.hist(img.ravel(),256,[0,256]); plt.show()
@endcode
 You will get a plot as below :
@@ -136,6 +138,7 @@ import cv2 as cv
 from matplotlib import pyplot as plt

 img = cv.imread('home.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"
 color = ('b','g','r')
 for i,col in enumerate(color):
    histr = cv.calcHist([img],[i],None,[256],[0,256])
@@ -164,7 +167,8 @@ We used cv.calcHist() to find the histogram of the full image. What if you want
 of some regions of an image? Just create a mask image with white color on the region you want to
 find histogram and black otherwise. Then pass this as the mask.
@code{.py}
-img = cv.imread('home.jpg',0)
+img = cv.imread('home.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"

 # create a mask
 mask = np.zeros(img.shape[:2], np.uint8)
@@ -30,7 +30,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('wiki.jpg',0)
+img = cv.imread('wiki.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"

 hist,bins = np.histogram(img.flatten(),256,[0,256])

@@ -81,7 +82,8 @@ output is our histogram equalized image.

 Below is a simple code snippet showing its usage for same image we used :
@code{.py}
-img = cv.imread('wiki.jpg',0)
+img = cv.imread('wiki.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 equ = cv.equalizeHist(img)
 res = np.hstack((img,equ)) #stacking images side-by-side
 cv.imwrite('res.png',res)
@@ -124,7 +126,8 @@ Below code snippet shows how to apply CLAHE in OpenCV:
 import numpy as np
 import cv2 as cv

-img = cv.imread('tsukuba_l.png',0)
+img = cv.imread('tsukuba_l.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"

 # create a CLAHE object (Arguments are optional).
 clahe = cv.createCLAHE(clipLimit=2.0, tileGridSize=(8,8))
@@ -23,7 +23,8 @@ explained in the documentation. So we directly go to the code.
 import numpy as np
 import cv2 as cv

-img = cv.imread('opencv-logo-white.png',0)
+img = cv.imread('opencv-logo-white.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 img = cv.medianBlur(img,5)
 cimg = cv.cvtColor(img,cv.COLOR_GRAY2BGR)

@@ -38,7 +38,8 @@ Here, as an example, I would use a 5x5 kernel with full of ones. Let's see it ho
 import cv2 as cv
 import numpy as np

-img = cv.imread('j.png',0)
+img = cv.imread('j.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 kernel = np.ones((5,5),np.uint8)
 erosion = cv.erode(img,kernel,iterations = 1)
@endcode
@@ -48,7 +49,7 @@ Result:

 ### 2. Dilation

-It is just opposite of erosion. Here, a pixel element is '1' if atleast one pixel under the kernel
+It is just opposite of erosion. Here, a pixel element is '1' if at least one pixel under the kernel
 is '1'. So it increases the white region in the image or size of foreground object increases.
 Normally, in cases like noise removal, erosion is followed by dilation. Because, erosion removes
 white noises, but it also shrinks our object. So we dilate it. Since noise is gone, they won't come
@@ -31,6 +31,7 @@ Similarly while expanding, area becomes 4 times in each level. We can find Gauss
 **cv.pyrDown()** and **cv.pyrUp()** functions.
@code{.py}
 img = cv.imread('messi5.jpg')
+assert img is not None, "file could not be read, check with os.path.exists()"
 lower_reso = cv.pyrDown(higher_reso)
@endcode
 Below is the 4 levels in an image pyramid.
@@ -84,6 +85,8 @@ import numpy as np,sys

 A = cv.imread('apple.jpg')
 B = cv.imread('orange.jpg')
+assert A is not None, "file could not be read, check with os.path.exists()"
+assert B is not None, "file could not be read, check with os.path.exists()"

 # generate Gaussian pyramid for A
 G = A.copy()
@@ -38,9 +38,11 @@ import cv2 as cv
 import numpy as np
 from matplotlib import pyplot as plt

-img = cv.imread('messi5.jpg',0)
+img = cv.imread('messi5.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 img2 = img.copy()
-template = cv.imread('template.jpg',0)
+template = cv.imread('template.jpg', cv.IMREAD_GRAYSCALE)
+assert template is not None, "file could not be read, check with os.path.exists()"
 w, h = template.shape[::-1]

 # All the 6 methods for comparison in a list
@@ -113,8 +115,10 @@ import numpy as np
 from matplotlib import pyplot as plt

 img_rgb = cv.imread('mario.png')
+assert img_rgb is not None, "file could not be read, check with os.path.exists()"
 img_gray = cv.cvtColor(img_rgb, cv.COLOR_BGR2GRAY)
-template = cv.imread('mario_coin.png',0)
+template = cv.imread('mario_coin.png', cv.IMREAD_GRAYSCALE)
+assert template is not None, "file could not be read, check with os.path.exists()"
 w, h = template.shape[::-1]

 res = cv.matchTemplate(img_gray,template,cv.TM_CCOEFF_NORMED)
@@ -37,7 +37,8 @@ import cv2 as cv
 import numpy as np
 from matplotlib import pyplot as plt

-img = cv.imread('gradient.png',0)
+img = cv.imread('gradient.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 ret,thresh1 = cv.threshold(img,127,255,cv.THRESH_BINARY)
 ret,thresh2 = cv.threshold(img,127,255,cv.THRESH_BINARY_INV)
 ret,thresh3 = cv.threshold(img,127,255,cv.THRESH_TRUNC)
@@ -85,7 +86,8 @@ import cv2 as cv
 import numpy as np
 from matplotlib import pyplot as plt

-img = cv.imread('sudoku.png',0)
+img = cv.imread('sudoku.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 img = cv.medianBlur(img,5)

 ret,th1 = cv.threshold(img,127,255,cv.THRESH_BINARY)
@@ -133,7 +135,8 @@ import cv2 as cv
 import numpy as np
 from matplotlib import pyplot as plt

-img = cv.imread('noisy2.png',0)
+img = cv.imread('noisy2.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"

 # global thresholding
 ret1,th1 = cv.threshold(img,127,255,cv.THRESH_BINARY)
@@ -183,7 +186,8 @@ where
 It actually finds a value of t which lies in between two peaks such that variances to both classes
 are minimal. It can be simply implemented in Python as follows:
@code{.py}
-img = cv.imread('noisy2.png',0)
+img = cv.imread('noisy2.png', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 blur = cv.GaussianBlur(img,(5,5),0)

 # find normalized_histogram, and its cumulative distribution function
@@ -54,7 +54,8 @@ import cv2 as cv
 import numpy as np
 from matplotlib import pyplot as plt

-img = cv.imread('messi5.jpg',0)
+img = cv.imread('messi5.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"
 f = np.fft.fft2(img)
 fshift = np.fft.fftshift(f)
 magnitude_spectrum = 20*np.log(np.abs(fshift))
@@ -121,7 +122,8 @@ import numpy as np
 import cv2 as cv
 from matplotlib import pyplot as plt

-img = cv.imread('messi5.jpg',0)
+img = cv.imread('messi5.jpg', cv.IMREAD_GRAYSCALE)
+assert img is not None, "file could not be read, check with os.path.exists()"

 dft = cv.dft(np.float32(img),flags = cv.DFT_COMPLEX_OUTPUT)
 dft_shift = np.fft.fftshift(dft)
@@ -184,7 +186,8 @@ So how do we find this optimal size ? OpenCV provides a function, **cv.getOptima
 this. It is applicable to both **cv.dft()** and **np.fft.fft2()**. Let's check their performance
 using IPython magic command %timeit.
@code{.py}
-In [16]: img = cv.imread('messi5.jpg',0)
+In [15]: img = cv.imread('messi5.jpg', cv.IMREAD_GRAYSCALE)
+In [16]: assert img is not None, "file could not be read, check with os.path.exists()"
 In [17]: rows,cols = img.shape
 In [18]: print("{} {}".format(rows,cols))
 342 548
@@ -49,6 +49,7 @@ import cv2 as cv
 from matplotlib import pyplot as plt

 img = cv.imread('coins.png')
+assert img is not None, "file could not be read, check with os.path.exists()"
 gray = cv.cvtColor(img,cv.COLOR_BGR2GRAY)
 ret, thresh = cv.threshold(gray,0,255,cv.THRESH_BINARY_INV+cv.THRESH_OTSU)
@endcode
@@ -56,7 +56,7 @@ import numpy as np
 import cv2 as cv

 img = cv.imread('messi_2.jpg')
-mask = cv.imread('mask2.png',0)
+mask = cv.imread('mask2.png', cv.IMREAD_GRAYSCALE)

 dst = cv.inpaint(img,mask,3,cv.INPAINT_TELEA)

@@ -30,7 +30,7 @@ programmer to express ideas in fewer lines of code without reducing readability.
 Compared to languages like C/C++, Python is slower. That said, Python can be easily extended with
 C/C++, which allows us to write computationally intensive code in C/C++ and create Python wrappers
 that can be used as Python modules. This gives us two advantages: first, the code is as fast as the
-original C/C++ code (since it is the actual C++ code working in background) and second, it easier to
+original C/C++ code (since it is the actual C++ code working in background) and second, it is easier to
 code in Python than C/C++. OpenCV-Python is a Python wrapper for the original OpenCV C++
 implementation.

@@ -79,8 +79,9 @@ Below is the list of contributors who submitted tutorials to OpenCV-Python.
 Additional Resources
 --------------------

-#  A Quick guide to Python - [A Byte of Python](http://swaroopch.com/notes/python/)
-2.  [NumPy Quickstart tutorial](https://numpy.org/devdocs/user/quickstart.html)
-3.  [NumPy Reference](https://numpy.org/devdocs/reference/index.html#reference)
-4.  [OpenCV Documentation](http://docs.opencv.org/)
+-#  A Quick guide to Python - [A Byte of Python](https://python.swaroopch.com/)
+1.  [A Quick guide to Python](https://www.freecodecamp.org/news/the-python-guide-for-beginners/)
+2.  [NumPy Quickstart tutorial](https://numpy.org/doc/stable/user/quickstart.html)
+3.  [NumPy Reference](https://numpy.org/doc/stable/reference/index.html)
+4.  [OpenCV Documentation](https://docs.opencv.org/)
 5.  [OpenCV Forum](https://forum.opencv.org/)
@@ -33,6 +33,8 @@ Installing OpenCV from prebuilt binaries

 -#  Copy **cv2.pyd** to **C:/Python27/lib/site-packages**.

+-#  Copy the **opencv_world.dll** file to **C:/Python27/lib/site-packages**
+
 -#  Open Python IDLE and type following codes in Python terminal.
    @code
        >>> import cv2 as cv
@@ -3,29 +3,30 @@
@prev_tutorial{tutorial_dnn_javascript}

 ## Introduction
-Deep learning is a fast growing area. The new approaches to build neural networks
-usually introduce new types of layers. They could be modifications of existing
-ones or implement outstanding researching ideas.
+Deep learning is a fast-growing area. New approaches to building neural networks
+usually introduce new types of layers. These could be modifications of existing
+ones or implementation of outstanding research ideas.

-OpenCV gives an opportunity to import and run networks from different deep learning
-frameworks. There are a number of the most popular layers. However you can face
-a problem that your network cannot be imported using OpenCV because of unimplemented layers.
+OpenCV allows importing and running networks from different deep learning frameworks.
+There is a number of the most popular layers. However, you can face a problem that
+your network cannot be imported using OpenCV because some layers of your network
+can be not implemented in the deep learning engine of OpenCV.

 The first solution is to create a feature request at https://github.com/opencv/opencv/issues
-mentioning details such a source of model and type of new layer. A new layer could
-be implemented if OpenCV community shares this need.
+mentioning details such as a source of a model and a type of new layer.
+The new layer could be implemented if the OpenCV community shares this need.

-The second way is to define a **custom layer** so OpenCV's deep learning engine
+The second way is to define a **custom layer** so that OpenCV's deep learning engine
 will know how to use it. This tutorial is dedicated to show you a process of deep
-learning models import customization.
+learning model's import customization.

 ## Define a custom layer in C++
 Deep learning layer is a building block of network's pipeline.
 It has connections to **input blobs** and produces results to **output blobs**.
 There are trained **weights** and **hyper-parameters**.
-Layers' names, types, weights and hyper-parameters are stored in files are generated by
-native frameworks during training. If OpenCV mets unknown layer type it throws an
-exception trying to read a model:
+Layers' names, types, weights and hyper-parameters are stored in files are
+generated by native frameworks during training. If OpenCV encounters unknown
+layer type it throws an exception while trying to read a model:

 ```
 Unspecified error: Can't create layer "layer_name" of type "MyType" in function getLayerInstance
@@ -61,7 +62,7 @@ This method should create an instance of you layer and return cv::Ptr with it.

@snippet dnn/custom_layers.hpp MyLayer::getMemoryShapes

-Returns layer's output shapes depends on input shapes. You may request an extra
+Returns layer's output shapes depending on input shapes. You may request an extra
 memory using `internals`.

 - Run a layer
@@ -71,20 +72,20 @@ memory using `internals`.
 Implement a layer's logic here. Compute outputs for given inputs.

@note OpenCV manages memory allocated for layers. In the most cases the same memory
-can be reused between layers. So your `forward` implementation should not rely that
-the second invocation of `forward` will has the same data at `outputs` and `internals`.
+can be reused between layers. So your `forward` implementation should not rely on that
+the second invocation of `forward` will have the same data at `outputs` and `internals`.

 - Optional `finalize` method

@snippet dnn/custom_layers.hpp MyLayer::finalize

-The chain of methods are the following: OpenCV deep learning engine calls `create`
-method once then it calls `getMemoryShapes` for an every created layer then you
-can make some preparations depends on known input dimensions at cv::dnn::Layer::finalize.
-After network was initialized only `forward` method is called for an every network's input.
+The chain of methods is the following: OpenCV deep learning engine calls `create`
+method once, then it calls `getMemoryShapes` for every created layer, then you
+can make some preparations depend on known input dimensions at cv::dnn::Layer::finalize.
+After network was initialized only `forward` method is called for every network's input.

-@note Varying input blobs' sizes such height or width or batch size you make OpenCV
-reallocate all the internal memory. That leads efficiency gaps. Try to initialize
+@note Varying input blobs' sizes such height, width or batch size make OpenCV
+reallocate all the internal memory. That leads to efficiency gaps. Try to initialize
 and deploy models using a fixed batch size and image's dimensions.

 ## Example: custom layer from Caffe
@@ -201,7 +202,7 @@ deep learning model. That was trained with one and only difference comparing to
 a current version of [Caffe framework](http://caffe.berkeleyvision.org/). `Crop`
 layers that receive two input blobs and crop the first one to match spatial dimensions
 of the second one used to crop from the center. Nowadays Caffe's layer does it
-from the top-left corner. So using the latest version of Caffe or OpenCV you'll
+from the top-left corner. So using the latest version of Caffe or OpenCV you will
 get shifted results with filled borders.

 Next we're going to replace OpenCV's `Crop` layer that makes top-left cropping by
@@ -217,7 +218,7 @@ a centric one.

@snippet dnn/edge_detection.py Register

-That's it! We've replaced an implemented OpenCV's layer to a custom one.
+That's it! We have replaced an implemented OpenCV's layer to a custom one.
 You may find a full script in the [source code](https://github.com/opencv/opencv/tree/3.4/samples/dnn/edge_detection.py).

 <table border="0">
@@ -10,9 +10,11 @@ Introduction {#tutorial_homography_Introduction}

 This tutorial will demonstrate the basic concepts of the homography with some codes.
 For detailed explanations about the theory, please refer to a computer vision course or a computer vision book, e.g.:
-*   Multiple View Geometry in Computer Vision, @cite HartleyZ00.
-*   An Invitation to 3-D Vision: From Images to Geometric Models, @cite Ma:2003:IVI
-*   Computer Vision: Algorithms and Applications, @cite RS10
+*   Multiple View Geometry in Computer Vision, Richard Hartley and Andrew Zisserman, @cite HartleyZ00 (some sample chapters are available [here](https://www.robots.ox.ac.uk/~vgg/hzbook/), CVPR Tutorials are available [here](https://www.robots.ox.ac.uk/~az/tutorials/))
+*   An Invitation to 3-D Vision: From Images to Geometric Models, Yi Ma, Stefano Soatto, Jana Kosecka, and S. Shankar Sastry, @cite Ma:2003:IVI (a computer vision book handout is available [here](https://cs.gmu.edu/%7Ekosecka/cs685/VisionBookHandout.pdf))
+*   Computer Vision: Algorithms and Applications, Richard Szeliski, @cite RS10 (an electronic version is available [here](https://szeliski.org/Book/))
+*   Deeper understanding of the homography decomposition for vision-based control, Ezio Malis, Manuel Vargas, @cite Malis2007 (open access [here](https://hal.inria.fr/inria-00174036))
+*   Pose Estimation for Augmented Reality: A Hands-On Survey, Eric Marchand, Hideaki Uchiyama, Fabien Spindler, @cite Marchand16 (open access [here](https://hal.inria.fr/hal-01246370))

 The tutorial code can be found here [C++](https://github.com/opencv/opencv/tree/3.4/samples/cpp/tutorial_code/features2D/Homography),
 [Python](https://github.com/opencv/opencv/tree/3.4/samples/python/tutorial_code/features2D/Homography),
@@ -32,7 +34,7 @@ Briefly, the planar homography relates the transformation between two planes (up
  x^{'} \\
  y^{'} \\
  1
-  \end{bmatrix} = H
+  \end{bmatrix} = \mathbf{H}
  \begin{bmatrix}
  x \\
  y \\
@@ -123,22 +125,22 @@ A quick solution to retrieve the pose from the homography matrix is (see \ref po

 \f[
  \begin{align*}
-  \boldsymbol{X} &= \left( X, Y, 0, 1 \right ) \\
-  \boldsymbol{x} &= \boldsymbol{P}\boldsymbol{X} \\
-                 &= \boldsymbol{K} \left[ \boldsymbol{r_1} \hspace{0.5em} \boldsymbol{r_2} \hspace{0.5em} \boldsymbol{r_3} \hspace{0.5em} \boldsymbol{t} \right ]
+  \mathbf{X} &= \left( X, Y, 0, 1 \right ) \\
+  \mathbf{x} &= \mathbf{P}\mathbf{X} \\
+                 &= \mathbf{K} \left[ \mathbf{r_1} \hspace{0.5em} \mathbf{r_2} \hspace{0.5em} \mathbf{r_3} \hspace{0.5em} \mathbf{t} \right ]
  \begin{pmatrix}
  X \\
  Y \\
  0 \\
  1
  \end{pmatrix} \\
-             &= \boldsymbol{K} \left[ \boldsymbol{r_1} \hspace{0.5em} \boldsymbol{r_2} \hspace{0.5em} \boldsymbol{t} \right ]
+             &= \mathbf{K} \left[ \mathbf{r_1} \hspace{0.5em} \mathbf{r_2} \hspace{0.5em} \mathbf{t} \right ]
  \begin{pmatrix}
  X \\
  Y \\
  1
  \end{pmatrix} \\
-  &= \boldsymbol{H}
+  &= \mathbf{H}
  \begin{pmatrix}
  X \\
  Y \\
@@ -149,16 +151,16 @@ A quick solution to retrieve the pose from the homography matrix is (see \ref po

 \f[
  \begin{align*}
-  \boldsymbol{H} &= \lambda \boldsymbol{K} \left[ \boldsymbol{r_1} \hspace{0.5em} \boldsymbol{r_2} \hspace{0.5em} \boldsymbol{t} \right ] \\
-  \boldsymbol{K}^{-1} \boldsymbol{H} &= \lambda \left[ \boldsymbol{r_1} \hspace{0.5em} \boldsymbol{r_2} \hspace{0.5em} \boldsymbol{t} \right ] \\
-  \boldsymbol{P} &= \boldsymbol{K} \left[ \boldsymbol{r_1} \hspace{0.5em} \boldsymbol{r_2} \hspace{0.5em} \left( \boldsymbol{r_1} \times \boldsymbol{r_2} \right ) \hspace{0.5em} \boldsymbol{t} \right ]
+  \mathbf{H} &= \lambda \mathbf{K} \left[ \mathbf{r_1} \hspace{0.5em} \mathbf{r_2} \hspace{0.5em} \mathbf{t} \right ] \\
+  \mathbf{K}^{-1} \mathbf{H} &= \lambda \left[ \mathbf{r_1} \hspace{0.5em} \mathbf{r_2} \hspace{0.5em} \mathbf{t} \right ] \\
+  \mathbf{P} &= \mathbf{K} \left[ \mathbf{r_1} \hspace{0.5em} \mathbf{r_2} \hspace{0.5em} \left( \mathbf{r_1} \times \mathbf{r_2} \right ) \hspace{0.5em} \mathbf{t} \right ]
  \end{align*}
 \f]

 This is a quick solution (see also \ref projective_transformations "2") as this does not ensure that the resulting rotation matrix will be orthogonal and the scale is estimated roughly by normalize the first column to 1.

-A solution to have a proper rotation matrix (with the properties of a rotation matrix) consists to apply a polar decomposition
-(see \ref polar_decomposition "6" or \ref polar_decomposition_svd "7" for some information):
+A solution to have a proper rotation matrix (with the properties of a rotation matrix) consists to apply a polar decomposition, or orthogonalization of the rotation matrix
+(see \ref polar_decomposition "6" or \ref polar_decomposition_svd "7" or \ref polar_decomposition_svd_2 "8" or \ref Kabsch_algorithm "9" for some information):

@snippet pose_from_homography.cpp polar-decomposition-of-the-rotation-matrix

@@ -239,7 +241,7 @@ To check the correctness of the calculation, the matching lines are displayed:

 ### Demo 3: Homography from the camera displacement {#tutorial_homography_Demo3}

-The homography relates the transformation between two planes and it is possible to retrieve the corresponding camera displacement that allows to go from the first to the second plane view (see @cite Malis for more information).
+The homography relates the transformation between two planes and it is possible to retrieve the corresponding camera displacement that allows to go from the first to the second plane view (see @cite Malis2007 for more information).
 Before going into the details that allow to compute the homography from the camera displacement, some recalls about camera pose and homogeneous transformation.

 The function @ref cv::solvePnP allows to compute the camera pose from the correspondences 3D object points (points expressed in the object frame) and the projected 2D image points (object points viewed in the image).
@@ -269,7 +271,7 @@ The intrinsic parameters and the distortion coefficients are required (see the c
  Z_o \\
  1
  \end{bmatrix} \\
-  &= \boldsymbol{K} \hspace{0.2em} ^{c}\textrm{M}_o
+  &= \mathbf{K} \hspace{0.2em} ^{c}\mathbf{M}_o
  \begin{bmatrix}
  X_o \\
  Y_o \\
@@ -279,9 +281,9 @@ The intrinsic parameters and the distortion coefficients are required (see the c
  \end{align*}
 \f]

-\f$ \boldsymbol{K} \f$ is the intrinsic matrix and \f$ ^{c}\textrm{M}_o \f$ is the camera pose. The output of @ref cv::solvePnP is exactly this: `rvec` is the Rodrigues rotation vector and `tvec` the translation vector.
+\f$ \mathbf{K} \f$ is the intrinsic matrix and \f$ ^{c}\mathbf{M}_o \f$ is the camera pose. The output of @ref cv::solvePnP is exactly this: `rvec` is the Rodrigues rotation vector and `tvec` the translation vector.

-\f$ ^{c}\textrm{M}_o \f$ can be represented in a homogeneous form and allows to transform a point expressed in the object frame into the camera frame:
+\f$ ^{c}\mathbf{M}_o \f$ can be represented in a homogeneous form and allows to transform a point expressed in the object frame into the camera frame:

 \f[
  \begin{align*}
@@ -291,7 +293,7 @@ The intrinsic parameters and the distortion coefficients are required (see the c
  Z_c \\
  1
  \end{bmatrix} &=
-  \hspace{0.2em} ^{c}\textrm{M}_o
+  \hspace{0.2em} ^{c}\mathbf{M}_o
  \begin{bmatrix}
  X_o \\
  Y_o \\
@@ -300,7 +302,7 @@ The intrinsic parameters and the distortion coefficients are required (see the c
  \end{bmatrix} \\
  &=
  \begin{bmatrix}
-  ^{c}\textrm{R}_o & ^{c}\textrm{t}_o \\
+  ^{c}\mathbf{R}_o & ^{c}\mathbf{t}_o \\
  0_{1\times3} & 1
  \end{bmatrix}
  \begin{bmatrix}
@@ -327,19 +329,19 @@ The intrinsic parameters and the distortion coefficients are required (see the c

 Transform a point expressed in one frame to another frame can be easily done with matrix multiplication:

-*   \f$ ^{c_1}\textrm{M}_o \f$ is the camera pose for the camera 1
-*   \f$ ^{c_2}\textrm{M}_o \f$ is the camera pose for the camera 2
+*   \f$ ^{c_1}\mathbf{M}_o \f$ is the camera pose for the camera 1
+*   \f$ ^{c_2}\mathbf{M}_o \f$ is the camera pose for the camera 2

 To transform a 3D point expressed in the camera 1 frame to the camera 2 frame:

 \f[
-  ^{c_2}\textrm{M}_{c_1} = \hspace{0.2em} ^{c_2}\textrm{M}_{o} \cdot \hspace{0.1em} ^{o}\textrm{M}_{c_1} = \hspace{0.2em} ^{c_2}\textrm{M}_{o} \cdot \hspace{0.1em} \left( ^{c_1}\textrm{M}_{o} \right )^{-1} =
+  ^{c_2}\mathbf{M}_{c_1} = \hspace{0.2em} ^{c_2}\mathbf{M}_{o} \cdot \hspace{0.1em} ^{o}\mathbf{M}_{c_1} = \hspace{0.2em} ^{c_2}\mathbf{M}_{o} \cdot \hspace{0.1em} \left( ^{c_1}\mathbf{M}_{o} \right )^{-1} =
  \begin{bmatrix}
-  ^{c_2}\textrm{R}_{o} & ^{c_2}\textrm{t}_{o} \\
+  ^{c_2}\mathbf{R}_{o} & ^{c_2}\mathbf{t}_{o} \\
  0_{3 \times 1} & 1
  \end{bmatrix} \cdot
  \begin{bmatrix}
-  ^{c_1}\textrm{R}_{o}^T & - \hspace{0.2em} ^{c_1}\textrm{R}_{o}^T \cdot \hspace{0.2em} ^{c_1}\textrm{t}_{o} \\
+  ^{c_1}\mathbf{R}_{o}^T & - \hspace{0.2em} ^{c_1}\mathbf{R}_{o}^T \cdot \hspace{0.2em} ^{c_1}\mathbf{t}_{o} \\
  0_{1 \times 3} & 1
  \end{bmatrix}
 \f]
@@ -362,11 +364,11 @@ On this figure, `n` is the normal vector of the plane and `d` the distance betwe
 The [equation](https://en.wikipedia.org/wiki/Homography_(computer_vision)#3D_plane_to_plane_equation) to compute the homography from the camera displacement is:

 \f[
-  ^{2}\textrm{H}_{1} = \hspace{0.2em} ^{2}\textrm{R}_{1} - \hspace{0.1em} \frac{^{2}\textrm{t}_{1} \cdot n^T}{d}
+  ^{2}\mathbf{H}_{1} = \hspace{0.2em} ^{2}\mathbf{R}_{1} - \hspace{0.1em} \frac{^{2}\mathbf{t}_{1} \cdot \hspace{0.1em} ^{1}\mathbf{n}^\top}{^1d}
 \f]

-Where \f$ ^{2}\textrm{H}_{1} \f$ is the homography matrix that maps the points in the first camera frame to the corresponding points in the second camera frame, \f$ ^{2}\textrm{R}_{1} = \hspace{0.2em} ^{c_2}\textrm{R}_{o} \cdot \hspace{0.1em} ^{c_1}\textrm{R}_{o}^{T} \f$
-is the rotation matrix that represents the rotation between the two camera frames and \f$ ^{2}\textrm{t}_{1} = \hspace{0.2em} ^{c_2}\textrm{R}_{o} \cdot \left( - \hspace{0.1em} ^{c_1}\textrm{R}_{o}^{T} \cdot \hspace{0.1em} ^{c_1}\textrm{t}_{o} \right ) + \hspace{0.1em} ^{c_2}\textrm{t}_{o} \f$
+Where \f$ ^{2}\mathbf{H}_{1} \f$ is the homography matrix that maps the points in the first camera frame to the corresponding points in the second camera frame, \f$ ^{2}\mathbf{R}_{1} = \hspace{0.2em} ^{c_2}\mathbf{R}_{o} \cdot \hspace{0.1em} ^{c_1}\mathbf{R}_{o}^{\top} \f$
+is the rotation matrix that represents the rotation between the two camera frames and \f$ ^{2}\mathbf{t}_{1} = \hspace{0.2em} ^{c_2}\mathbf{R}_{o} \cdot \left( - \hspace{0.1em} ^{c_1}\mathbf{R}_{o}^{\top} \cdot \hspace{0.1em} ^{c_1}\mathbf{t}_{o} \right ) + \hspace{0.1em} ^{c_2}\mathbf{t}_{o} \f$
 the translation vector between the two camera frames.

 Here the normal vector `n` is the plane normal expressed in the camera frame 1 and can be computed as the cross product of 2 vectors (using 3 non collinear points that lie on the plane) or in our case directly with:
@@ -377,7 +379,7 @@ The distance `d` can be computed as the dot product between the plane normal and

@snippet homography_from_camera_displacement.cpp compute-plane-distance-to-the-camera-frame-1

-The projective homography matrix \f$ \textbf{G} \f$ can be computed from the Euclidean homography \f$ \textbf{H} \f$ using the intrinsic matrix \f$ \textbf{K} \f$ (see @cite Malis), here assuming the same camera between the two plane views:
+The projective homography matrix \f$ \textbf{G} \f$ can be computed from the Euclidean homography \f$ \textbf{H} \f$ using the intrinsic matrix \f$ \textbf{K} \f$ (see @cite Malis2007), here assuming the same camera between the two plane views:

 \f[
  \textbf{G} = \gamma \textbf{K} \textbf{H} \textbf{K}^{-1}
@@ -388,7 +390,7 @@ The projective homography matrix \f$ \textbf{G} \f$ can be computed from the Euc
 In our case, the Z-axis of the chessboard goes inside the object whereas in the homography figure it goes outside. This is just a matter of sign:

 \f[
-  ^{2}\textrm{H}_{1} = \hspace{0.2em} ^{2}\textrm{R}_{1} + \hspace{0.1em} \frac{^{2}\textrm{t}_{1} \cdot n^T}{d}
+  ^{2}\mathbf{H}_{1} = \hspace{0.2em} ^{2}\mathbf{R}_{1} + \hspace{0.1em} \frac{^{2}\mathbf{t}_{1} \cdot \hspace{0.1em} ^{1}\mathbf{n}^\top}{^1d}
 \f]

@snippet homography_from_camera_displacement.cpp compute-homography-from-camera-displacement
@@ -410,10 +412,18 @@ homography from camera displacement:

 The homography matrices are similar. If we compare the image 1 warped using both homography matrices:

-![Left: image warped using the homography estimated. Right: using the homography computed from the camera displacement](images/homography_camera_displacement_compare.jpg)
+![Left: image warped using the estimated homography. Right: using the homography computed from the camera displacement.](images/homography_camera_displacement_compare.jpg)

 Visually, it is hard to distinguish a difference between the result image from the homography computed from the camera displacement and the one estimated with @ref cv::findHomography function.

+#### Exercise
+
+This demo shows you how to compute the homography transformation from two camera poses. Try to perform the same operations, but by computing N inter homography this time. Instead of computing one homography to directly warp the source image to the desired camera viewpoint, perform N warping operations to see the different transformations operating.
+
+You should get something similar to the following:
+
+![The first three images show the source image warped at three different interpolated camera viewpoints. The 4th image shows the "error image" between the warped source image at the final camera viewpoint and the desired image.](images/homography_camera_poses_interpolation.jpg)
+
 ### Demo 4: Decompose the homography matrix {#tutorial_homography_Demo4}

 OpenCV 3 contains the function @ref cv::decomposeHomographyMat which allows to decompose the homography matrix to a set of rotations, translations and plane normals.
@@ -466,8 +476,8 @@ As you can see, there is one solution that matches almost perfectly with the com
 At least two of the solutions may further be invalidated if point correspondences are available by applying positive depth constraint (all points must be in front of the camera).
 ```

-As the result of the decomposition is a camera displacement, if we have the initial camera pose \f$ ^{c_1}\textrm{M}_{o} \f$, we can compute the current camera pose
-\f$ ^{c_2}\textrm{M}_{o} = \hspace{0.2em} ^{c_2}\textrm{M}_{c_1} \cdot \hspace{0.1em} ^{c_1}\textrm{M}_{o} \f$ and test if the 3D object points that belong to the plane are projected in front of the camera or not.
+As the result of the decomposition is a camera displacement, if we have the initial camera pose \f$ ^{c_1}\mathbf{M}_{o} \f$, we can compute the current camera pose
+\f$ ^{c_2}\mathbf{M}_{o} = \hspace{0.2em} ^{c_2}\mathbf{M}_{c_1} \cdot \hspace{0.1em} ^{c_1}\mathbf{M}_{o} \f$ and test if the 3D object points that belong to the plane are projected in front of the camera or not.
 Another solution could be to retain the solution with the closest normal if we know the plane normal expressed at the camera 1 pose.

 The same thing but with the homography matrix estimated with @ref cv::findHomography
@@ -516,7 +526,7 @@ The [stitching module](@ref stitching) provides a complete pipeline to stitch im
 The homography transformation applies only for planar structure. But in the case of a rotating camera (pure rotation around the camera axis of projection, no translation), an arbitrary world can be considered
 ([see previously](@ref tutorial_homography_What_is_the_homography_matrix)).

-The homography can then be computed using the rotation transformation and the camera intrinsic parameters as (see for instance \ref homography_course "8"):
+The homography can then be computed using the rotation transformation and the camera intrinsic parameters as (see for instance \ref homography_course "10"):

 \f[
  s
@@ -534,7 +544,7 @@ The homography can then be computed using the rotation transformation and the ca
 \f]

 To illustrate, we used Blender, a free and open-source 3D computer graphics software, to generate two camera views with only a rotation transformation between each other.
-More information about how to retrieve the camera intrinsic parameters and the `3x4` extrinsic matrix with respect to the world can be found in \ref answer_blender "9" (an additional transformation
+More information about how to retrieve the camera intrinsic parameters and the `3x4` extrinsic matrix with respect to the world can be found in \ref answer_blender "11" (an additional transformation
 is needed to get the transformation between the camera and the object frames) with Blender.

 The figure below shows the two generated views of the Suzanne model, with only a rotation transformation:
@@ -603,11 +613,13 @@ Additional references {#tutorial_homography_Additional_references}
 ---------------------

 *   \anchor lecture_16 1. [Lecture 16: Planar Homographies](http://www.cse.psu.edu/~rtc12/CSE486/lecture16.pdf), Robert Collins
-*   \anchor projective_transformations 2. [2D projective transformations (homographies)](https://ags.cs.uni-kl.de/fileadmin/inf_ags/3dcv-ws11-12/3DCV_WS11-12_lec04.pdf), Christiano Gava, Gabriele Bleser
-*   \anchor szeliski 3. [Computer Vision: Algorithms and Applications](http://szeliski.org/Book/drafts/SzeliskiBook_20100903_draft.pdf), Richard Szeliski
+*   \anchor projective_transformations 2. [2D projective transformations (homographies)](https://web.archive.org/web/20171226115739/https://ags.cs.uni-kl.de/fileadmin/inf_ags/3dcv-ws11-12/3DCV_WS11-12_lec04.pdf), Christiano Gava, Gabriele Bleser
+*   \anchor szeliski 3. [Computer Vision: Algorithms and Applications](https://szeliski.org/Book/), Richard Szeliski
 *   \anchor answer_dsp 4. [Step by Step Camera Pose Estimation for Visual Tracking and Planar Markers](https://dsp.stackexchange.com/a/2737)
-*   \anchor pose_ar 5. [Pose from homography estimation](https://team.inria.fr/lagadic/camera_localization/tutorial-pose-dlt-planar-opencv.html)
+*   \anchor pose_ar 5. [Pose from homography estimation](https://visp-doc.inria.fr/doxygen/camera_localization/tutorial-pose-dlt-planar-opencv.html)
 *   \anchor polar_decomposition 6. [Polar Decomposition (in Continuum Mechanics)](http://www.continuummechanics.org/polardecomposition.html)
-*   \anchor polar_decomposition_svd 7. [A Personal Interview with the Singular Value Decomposition](https://web.stanford.edu/~gavish/documents/SVD_ans_you.pdf), Matan Gavish
-*   \anchor homography_course 8. [Homography](http://people.scs.carleton.ca/~c_shu/Courses/comp4900d/notes/homography.pdf), Dr. Gerhard Roth
-*   \anchor answer_blender 9. [3x4 camera matrix from blender camera](https://blender.stackexchange.com/a/38210)
+*   \anchor polar_decomposition_svd 7. [Chapter 3 - 3.1.2 From matrices to rotations - Theorem 3.1 (Least-squares estimation of a rotation from a matrix K)](https://www-sop.inria.fr/asclepios/cours/MVA/Rotations.pdf)
+*   \anchor polar_decomposition_svd_2 8. [A Personal Interview with the Singular Value Decomposition](https://web.stanford.edu/~gavish/documents/SVD_ans_you.pdf), Matan Gavish
+*   \anchor Kabsch_algorithm 9. [Kabsch algorithm, Computation of the optimal rotation matrix](https://en.wikipedia.org/wiki/Kabsch_algorithm#Computation_of_the_optimal_rotation_matrix)
+*   \anchor homography_course 10. [Homography](http://people.scs.carleton.ca/~c_shu/Courses/comp4900d/notes/homography.pdf), Dr. Gerhard Roth
+*   \anchor answer_blender 11. [3x4 camera matrix from blender camera](https://blender.stackexchange.com/a/38210)
@@ -0,0 +1,92 @@
+Object detection with Generalized Ballard and Guil Hough Transform {#tutorial_generalized_hough_ballard_guil}
+==================================================================
+
+@tableofcontents
+
+@prev_tutorial{tutorial_hough_circle}
+@next_tutorial{tutorial_remap}
+
+Goal
+----
+
+In this tutorial you will learn how to:
+
+- Use @ref cv::GeneralizedHoughBallard and @ref cv::GeneralizedHoughGuil to detect an object
+
+Example
+-------
+
+### What does this program do?
+
+1. Load the image and template
+
+![image](images/generalized_hough_mini_image.jpg)
+![template](images/generalized_hough_mini_template.jpg)
+
+2. Instantiate @ref cv::GeneralizedHoughBallard with the help of `createGeneralizedHoughBallard()`
+3. Instantiate @ref cv::GeneralizedHoughGuil with the help of `createGeneralizedHoughGuil()`
+4. Set the required parameters for both GeneralizedHough variants
+5. Detect and show found results
+
+@note
+- Both variants can't be instantiated directly. Using the create methods is required.
+- Guil Hough is very slow. Calculating the results for the "mini" files used in this tutorial
+  takes only a few seconds. With image and template in a higher resolution, as shown below,
+  my notebook requires about 5 minutes to calculate a result.
+
+![image](images/generalized_hough_image.jpg)
+![template](images/generalized_hough_template.jpg)
+
+### Code
+
+The complete code for this tutorial is shown below.
+@include samples/cpp/tutorial_code/ImgTrans/generalizedHoughTransform.cpp
+
+Explanation
+-----------
+
+### Load image, template and setup variables
+
+@snippet samples/cpp/tutorial_code/ImgTrans/generalizedHoughTransform.cpp generalized-hough-transform-load-and-setup
+
+The position vectors will contain the matches the detectors will find.
+Every entry contains four floating point values:
+position vector
+
+- *[0]*: x coordinate of center point
+- *[1]*: y coordinate of center point
+- *[2]*: scale of detected object compared to template
+- *[3]*: rotation of detected object in degree in relation to template
+
+An example could look as follows: `[200, 100, 0.9, 120]`
+
+### Setup parameters
+
+@snippet samples/cpp/tutorial_code/ImgTrans/generalizedHoughTransform.cpp generalized-hough-transform-setup-parameters
+
+Finding the optimal values can end up in trial and error and depends on many factors, such as the image resolution.
+
+### Run detection
+
+@snippet samples/cpp/tutorial_code/ImgTrans/generalizedHoughTransform.cpp generalized-hough-transform-run
+
+As mentioned above, this step will take some time, especially with larger images and when using Guil.
+
+### Draw results and show image
+
+@snippet samples/cpp/tutorial_code/ImgTrans/generalizedHoughTransform.cpp generalized-hough-transform-draw-results
+
+Result
+------
+
+![result image](images/generalized_hough_result_img.jpg)
+
+The blue rectangle shows the result of @ref cv::GeneralizedHoughBallard and the green rectangles the results of @ref
+cv::GeneralizedHoughGuil.
+
+Getting perfect results like in this example is unlikely if the parameters are not perfectly adapted to the sample.
+An example with less perfect parameters is shown below.
+For the Ballard variant, only the center of the result is marked as a black dot on this image. The rectangle would be
+the same as on the previous image.
+
+![less perfect result](images/generalized_hough_less_perfect_result_img.jpg)
--- a/Show More
+++ b/Show More