Doxygen: Refactor Doxyfile.in to doxygen/Doxyfile.

Instead of having Doxyfile.in configured by Autoconf, the Doxyfile
can have the tags that need to be configured piped into the doxygen
command through stdin with the overrides after Doxyfile's contents.

Going forward, the documentation should be generated in two different
modes: liblzma or internal.

liblzma is useful for most users. It is the documentation for just
the liblzma API header files. This is the default.

internal is for people who want to understand how xz and liblzma work.
It might be useful for people who want to contribute to the project.

4 files changed, 456 insertions, 309 deletions

diff --git a/.gitignore b/.gitignore
index d6b144f1..c5883bba 100644
--- a/.gitignore
+++ b/.gitignore
@@ -38,7 +38,8 @@ build-aux/test-driver
 
 coverage
 
-/doc/html
+/doc/internal
+/doc/liblzma
 
 /src/liblzma/liblzma.pc
 /src/lzmainfo/lzmainfo
diff --git a/Makefile.am b/Makefile.am
index c4a46187..1756e5cb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -55,7 +55,6 @@ EXTRA_DIST = \
 	cmake \
 	CMakeLists.txt \
 	autogen.sh \
-	Doxyfile.in \
 	COPYING.GPLv2 \
 	COPYING.GPLv3 \
 	COPYING.LGPLv2.1 \
diff --git a/configure.ac b/configure.ac
index ad94e01a..631b1877 100644
--- a/configure.ac
+++ b/configure.ac
@@ -520,45 +520,6 @@ AC_ARG_ENABLE([doc], [AS_HELP_STRING([--disable-doc],
 AM_CONDITIONAL([COND_DOC], [test x$enable_doc != xno])
 
 
-###########
-# Doxygen #
-###########
-
-# Doxygen can be enabled in two different modes:
-# api - Only generate Doxygen html pages for liblzma API headers.
-# all - Generate Doxygen html pages for every file.
-# api mode is the default because the primary purpose for the doxygen
-# documentation is to publicaly describe liblzma's API. The other html
-# pages are only useful for those who want to understand or alter the
-# internals of xz and liblzma.
-
-AC_ARG_ENABLE([doxygen], [AS_HELP_STRING([--enable-doxygen=SCOPE],
-			[Doxygen SCOPE can be `all', or `api'.
-			The default is `api', which will generate doxygen html
-			for liblzma API. The `all' option will generate doxygen
-			html for every .c and .h file.])],
-		[], [enable_doxygen=api])
-case $enable_doxygen in
-	api)
-		doxygen_project_name="liblzma ($PACKAGE_NAME)"
-		doxygen_extract_private=NO
-		doxygen_input_path=src/liblzma/api
-		;;
-	all)
-		doxygen_project_name="$PACKAGE_NAME"
-		doxygen_extract_private=YES
-		doxygen_input_path=src
-		;;
-	*)
-		AC_MSG_ERROR([--enable-doxygen only accepts `all' or `api'])
-		;;
-esac
-
-AC_SUBST([doxygen_project_name])
-AC_SUBST([doxygen_extract_private])
-AC_SUBST([doxygen_input_path])
-
-
 ##############
 # Sandboxing #
 ##############
@@ -1171,7 +1132,6 @@ xz=`echo xz | sed "$program_transform_name"`
 AC_SUBST([xz])
 
 AC_CONFIG_FILES([
-	Doxyfile
 	Makefile
 	po/Makefile.in
 	lib/Makefile
diff --git a/Doxyfile.in b/doxygen/Doxyfile
index a1795d10..f18d18cd 100644
--- a/Doxyfile.in
+++ b/doxygen/Doxyfile
@@ -1,4 +1,4 @@
-# Doxyfile 1.8.17
+# Doxyfile 1.9.6
 
 # This file describes the settings to be used by the documentation system
 # doxygen (www.doxygen.org) for a project.
@@ -12,6 +12,16 @@
 # For lists, items can also be appended using:
 # TAG += value [value, ...]
 # Values that contain spaces should be placed between quotes (\" \").
+#
+# Note:
+#
+# Use doxygen to compare the used configuration file with the template
+# configuration file:
+# doxygen -x [configFile]
+# Use doxygen to compare the used configuration file with the template
+# configuration file without replacing the environment variables or CMake type
+# replacement variables:
+# doxygen -x_noenv [configFile]
 
 #---------------------------------------------------------------------------
 # Project related configuration options
@@ -32,13 +42,13 @@ DOXYFILE_ENCODING      = UTF-8
 # title of most generated pages and in a few other places.
 # The default value is: My Project.
 
-PROJECT_NAME           = "@doxygen_project_name@"
+PROJECT_NAME           = "liblzma (XZ Utils)"
 
 # The PROJECT_NUMBER tag can be used to enter a project or revision number. This
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = "@PACKAGE_VERSION@"
+PROJECT_NUMBER         =
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
@@ -58,18 +68,30 @@ PROJECT_LOGO           =
 # entered, it will be relative to the location where doxygen was started. If
 # left blank the current directory will be used.
 
-OUTPUT_DIRECTORY       = doc
+OUTPUT_DIRECTORY       = ../doc
 
-# If the CREATE_SUBDIRS tag is set to YES then doxygen will create 4096 sub-
-# directories (in 2 levels) under the output directory of each output format and
-# will distribute the generated files over these directories. Enabling this
+# If the CREATE_SUBDIRS tag is set to YES then doxygen will create up to 4096
+# sub-directories (in 2 levels) under the output directory of each output format
+# and will distribute the generated files over these directories. Enabling this
 # option can be useful when feeding doxygen a huge amount of source files, where
 # putting all generated files in the same directory would otherwise causes
-# performance problems for the file system.
+# performance problems for the file system. Adapt CREATE_SUBDIRS_LEVEL to
+# control the number of sub-directories.
 # The default value is: NO.
 
 CREATE_SUBDIRS         = NO
 
+# Controls the number of sub-directories that will be created when
+# CREATE_SUBDIRS tag is set to YES. Level 0 represents 16 directories, and every
+# level increment doubles the number of directories, resulting in 4096
+# directories at level 8 which is the default and also the maximum value. The
+# sub-directories are organized in 2 levels, the first level always has a fixed
+# number of 16 directories.
+# Minimum value: 0, maximum value: 8, default value: 8.
+# This tag requires that the tag CREATE_SUBDIRS is set to YES.
+
+CREATE_SUBDIRS_LEVEL   = 8
+
 # If the ALLOW_UNICODE_NAMES tag is set to YES, doxygen will allow non-ASCII
 # characters to appear in the names of generated files. If set to NO, non-ASCII
 # characters will be escaped, for example _xE3_x81_x84 will be used for Unicode
@@ -81,26 +103,18 @@ ALLOW_UNICODE_NAMES    = NO
 # The OUTPUT_LANGUAGE tag is used to specify the language in which all
 # documentation generated by doxygen is written. Doxygen will use this
 # information to generate all constant output in the proper language.
-# Possible values are: Afrikaans, Arabic, Armenian, Brazilian, Catalan, Chinese,
-# Chinese-Traditional, Croatian, Czech, Danish, Dutch, English (United States),
-# Esperanto, Farsi (Persian), Finnish, French, German, Greek, Hungarian,
-# Indonesian, Italian, Japanese, Japanese-en (Japanese with English messages),
-# Korean, Korean-en (Korean with English messages), Latvian, Lithuanian,
-# Macedonian, Norwegian, Persian (Farsi), Polish, Portuguese, Romanian, Russian,
-# Serbian, Serbian-Cyrillic, Slovak, Slovene, Spanish, Swedish, Turkish,
-# Ukrainian and Vietnamese.
+# Possible values are: Afrikaans, Arabic, Armenian, Brazilian, Bulgarian,
+# Catalan, Chinese, Chinese-Traditional, Croatian, Czech, Danish, Dutch, English
+# (United States), Esperanto, Farsi (Persian), Finnish, French, German, Greek,
+# Hindi, Hungarian, Indonesian, Italian, Japanese, Japanese-en (Japanese with
+# English messages), Korean, Korean-en (Korean with English messages), Latvian,
+# Lithuanian, Macedonian, Norwegian, Persian (Farsi), Polish, Portuguese,
+# Romanian, Russian, Serbian, Serbian-Cyrillic, Slovak, Slovene, Spanish,
+# Swedish, Turkish, Ukrainian and Vietnamese.
 # The default value is: English.
 
 OUTPUT_LANGUAGE        = English
 
-# The OUTPUT_TEXT_DIRECTION tag is used to specify the direction in which all
-# documentation generated by doxygen is written. Doxygen will use this
-# information to generate all generated output in the proper direction.
-# Possible values are: None, LTR, RTL and Context.
-# The default value is: None.
-
-OUTPUT_TEXT_DIRECTION  = None
-
 # If the BRIEF_MEMBER_DESC tag is set to YES, doxygen will include brief member
 # descriptions after the members that are listed in the file and class
 # documentation (similar to Javadoc). Set to NO to disable this.
@@ -160,7 +174,7 @@ FULL_PATH_NAMES        = YES
 # will be relative from the directory where doxygen is started.
 # This tag requires that the tag FULL_PATH_NAMES is set to YES.
 
-STRIP_FROM_PATH        = @top_srcdir@/@doxygen_input_path@
+STRIP_FROM_PATH        = ../src/liblzma/api
 
 # The STRIP_FROM_INC_PATH tag can be used to strip a user-defined part of the
 # path mentioned in the documentation of a class, which tells the reader which
@@ -217,6 +231,14 @@ QT_AUTOBRIEF           = NO
 
 MULTILINE_CPP_IS_BRIEF = NO
 
+# By default Python docstrings are displayed as preformatted text and doxygen's
+# special commands cannot be used. By setting PYTHON_DOCSTRING to NO the
+# doxygen's special commands can be used and the contents of the docstring
+# documentation blocks is shown as doxygen documentation.
+# The default value is: YES.
+
+PYTHON_DOCSTRING       = YES
+
 # If the INHERIT_DOCS tag is set to YES then an undocumented member inherits the
 # documentation from any documented member that it re-implements.
 # The default value is: YES.
@@ -240,25 +262,19 @@ TAB_SIZE               = 8
 # the documentation. An alias has the form:
 # name=value
 # For example adding
-# "sideeffect=@par Side Effects:\n"
+# "sideeffect=@par Side Effects:^^"
 # will allow you to put the command \sideeffect (or @sideeffect) in the
 # documentation, which will result in a user-defined paragraph with heading
-# "Side Effects:". You can put \n's in the value part of an alias to insert
-# newlines (in the resulting output). You can put ^^ in the value part of an
-# alias to insert a newline as if a physical newline was in the original file.
-# When you need a literal { or } or , in the value part of an alias you have to
-# escape them by means of a backslash (\), this can lead to conflicts with the
-# commands \{ and \} for these it is advised to use the version @{ and @} or use
-# a double escape (\\{ and \\})
+# "Side Effects:". Note that you cannot put \n's in the value part of an alias
+# to insert newlines (in the resulting output). You can put ^^ in the value part
+# of an alias to insert a newline as if a physical newline was in the original
+# file. When you need a literal { or } or , in the value part of an alias you
+# have to escape them by means of a backslash (\), this can lead to conflicts
+# with the commands \{ and \} for these it is advised to use the version @{ and
+# @} or use a double escape (\\{ and \\})
 
 ALIASES                =
 
-# This tag can be used to specify a number of word-keyword mappings (TCL only).
-# A mapping has the form "name=value". For example adding "class=itcl::class"
-# will allow you to use the command class in the itcl::class meaning.
-
-TCL_SUBST              =
-
 # Set the OPTIMIZE_OUTPUT_FOR_C tag to YES if your project consists of C sources
 # only. Doxygen will then generate output that is more tailored for C. For
 # instance, some of the names that are used will be different. The list of all
@@ -267,23 +283,54 @@ TCL_SUBST              =
 
 OPTIMIZE_OUTPUT_FOR_C  = YES
 
+# Set the OPTIMIZE_OUTPUT_JAVA tag to YES if your project consists of Java or
+# Python sources only. Doxygen will then generate output that is more tailored
+# for that language. For instance, namespaces will be presented as packages,
+# qualified scopes will look different, etc.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_JAVA   = NO
+
+# Set the OPTIMIZE_FOR_FORTRAN tag to YES if your project consists of Fortran
+# sources. Doxygen will then generate output that is tailored for Fortran.
+# The default value is: NO.
+
+OPTIMIZE_FOR_FORTRAN   = NO
+
+# Set the OPTIMIZE_OUTPUT_VHDL tag to YES if your project consists of VHDL
+# sources. Doxygen will then generate output that is tailored for VHDL.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_VHDL   = NO
+
+# Set the OPTIMIZE_OUTPUT_SLICE tag to YES if your project consists of Slice
+# sources only. Doxygen will then generate output that is more tailored for that
+# language. For instance, namespaces will be presented as modules, types will be
+# separated into more groups, etc.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_SLICE  = NO
+
 # Doxygen selects the parser to use depending on the extension of the files it
 # parses. With this tag you can assign which parser to use for a given
 # extension. Doxygen has a built-in mapping, but you can override or extend it
 # using this tag. The format is ext=language, where ext is a file extension, and
 # language is one of the parsers supported by doxygen: IDL, Java, JavaScript,
-# Csharp (C#), C, C++, D, PHP, md (Markdown), Objective-C, Python, Slice,
-# Fortran (fixed format Fortran: FortranFixed, free formatted Fortran:
+# Csharp (C#), C, C++, Lex, D, PHP, md (Markdown), Objective-C, Python, Slice,
+# VHDL, Fortran (fixed format Fortran: FortranFixed, free formatted Fortran:
 # FortranFree, unknown formatted Fortran: Fortran. In the later case the parser
 # tries to guess whether the code is fixed or free formatted code, this is the
-# default for Fortran type files), VHDL, tcl. For instance to make doxygen treat
-# .inc files as Fortran files (default is PHP), and .f files as C (default is
-# Fortran), use: inc=Fortran f=C.
+# default for Fortran type files). For instance to make doxygen treat .inc files
+# as Fortran files (default is PHP), and .f files as C (default is Fortran),
+# use: inc=Fortran f=C.
 #
 # Note: For files without extension you can use no_extension as a placeholder.
 #
 # Note that for custom extensions you also need to set FILE_PATTERNS otherwise
-# the files are not read by doxygen.
+# the files are not read by doxygen. When specifying no_extension you should add
+# * to the FILE_PATTERNS.
+#
+# Note see also the list of default file extension mappings.
 
 EXTENSION_MAPPING      =
 
@@ -417,6 +464,19 @@ TYPEDEF_HIDES_STRUCT   = NO
 
 LOOKUP_CACHE_SIZE      = 0
 
+# The NUM_PROC_THREADS specifies the number of threads doxygen is allowed to use
+# during processing. When set to 0 doxygen will based this on the number of
+# cores available in the system. You can set it explicitly to a value larger
+# than 0 to get more control over the balance between CPU load and processing
+# speed. At this moment only the input processing can be done using multiple
+# threads. Since this is still an experimental feature the default is set to 1,
+# which effectively disables parallel processing. Please report any issues you
+# encounter. Generating dot graphs in parallel is controlled by the
+# DOT_NUM_THREADS setting.
+# Minimum value: 0, maximum value: 32, default value: 1.
+
+NUM_PROC_THREADS       = 1
+
 #---------------------------------------------------------------------------
 # Build related configuration options
 #---------------------------------------------------------------------------
@@ -435,7 +495,7 @@ EXTRACT_ALL            = NO
 # be included in the documentation.
 # The default value is: NO.
 
-EXTRACT_PRIVATE        = @doxygen_extract_private@
+EXTRACT_PRIVATE        = NO
 
 # If the EXTRACT_PRIV_VIRTUAL tag is set to YES, documented private virtual
 # methods of a class will be included in the documentation.
@@ -453,7 +513,7 @@ EXTRACT_PACKAGE        = NO
 # included in the documentation.
 # The default value is: NO.
 
-EXTRACT_STATIC         = @doxygen_extract_private@
+EXTRACT_STATIC         = NO
 
 # If the EXTRACT_LOCAL_CLASSES tag is set to YES, classes (and structs) defined
 # locally in source files will be included in the documentation. If set to NO,
@@ -461,7 +521,7 @@ EXTRACT_STATIC         = @doxygen_extract_private@
 # for Java sources.
 # The default value is: YES.
 
-EXTRACT_LOCAL_CLASSES  = @doxygen_extract_private@
+EXTRACT_LOCAL_CLASSES  = NO
 
 # This flag is only useful for Objective-C code. If set to YES, local methods,
 # which are defined in the implementation section but not in the interface are
@@ -480,6 +540,13 @@ EXTRACT_LOCAL_METHODS  = NO
 
 EXTRACT_ANON_NSPACES   = NO
 
+# If this flag is set to YES, the name of an unnamed parameter in a declaration
+# will be determined by the corresponding definition. By default unnamed
+# parameters remain unnamed in the output.
+# The default value is: YES.
+
+RESOLVE_UNNAMED_PARAMS = YES
+
 # If the HIDE_UNDOC_MEMBERS tag is set to YES, doxygen will hide all
 # undocumented members inside documented classes or files. If set to NO these
 # members will be included in the various overviews, but no documentation
@@ -491,7 +558,8 @@ HIDE_UNDOC_MEMBERS     = NO
 # If the HIDE_UNDOC_CLASSES tag is set to YES, doxygen will hide all
 # undocumented classes that are normally visible in the class hierarchy. If set
 # to NO, these classes will be included in the various overviews. This option
-# has no effect if EXTRACT_ALL is enabled.
+# will also hide undocumented C++ concepts if enabled. This option has no effect
+# if EXTRACT_ALL is enabled.
 # The default value is: NO.
 
 HIDE_UNDOC_CLASSES     = NO
@@ -517,12 +585,20 @@ HIDE_IN_BODY_DOCS      = NO
 
 INTERNAL_DOCS          = NO
 
-# If the CASE_SENSE_NAMES tag is set to NO then doxygen will only generate file
-# names in lower-case letters. If set to YES, upper-case letters are also
-# allowed. This is useful if you have classes or files whose names only differ
-# in case and if your file system supports case sensitive file names. Windows
-# (including Cygwin) ands Mac users are advised to set this option to NO.
-# The default value is: system dependent.
+# With the correct setting of option CASE_SENSE_NAMES doxygen will better be
+# able to match the capabilities of the underlying filesystem. In case the
+# filesystem is case sensitive (i.e. it supports files in the same directory
+# whose names only differ in casing), the option must be set to YES to properly
+# deal with such files in case they appear in the input. For filesystems that
+# are not case sensitive the option should be set to NO to properly deal with
+# output files written for symbols that only differ in casing, such as for two
+# classes, one named CLASS and the other named Class, and to also support
+# references to files without having to specify the exact matching casing. On
+# Windows (including Cygwin) and MacOS, users should typically set this option
+# to NO, whereas on Linux or other Unix flavors it should typically be set to
+# YES.
+# Possible values are: SYSTEM, NO and YES.
+# The default value is: SYSTEM.
 
 CASE_SENSE_NAMES       = YES
 
@@ -540,6 +616,12 @@ HIDE_SCOPE_NAMES       = NO
 
 HIDE_COMPOUND_REFERENCE= NO
 
+# If the SHOW_HEADERFILE tag is set to YES then the documentation for a class
+# will show which file needs to be included to use the class.
+# The default value is: YES.
+
+SHOW_HEADERFILE        = YES
+
 # If the SHOW_INCLUDE_FILES tag is set to YES then doxygen will put a list of
 # the files that are included by a file in the documentation of that file.
 # The default value is: YES.
@@ -697,7 +779,8 @@ FILE_VERSION_FILTER    =
 # output files in an output format independent way. To create the layout file
 # that represents doxygen's defaults, run doxygen with the -l option. You can
 # optionally specify a file name after the option, if omitted DoxygenLayout.xml
-# will be used as the name of the layout file.
+# will be used as the name of the layout file. See also section "Changing the
+# layout of pages" for information.
 #
 # Note that if you run doxygen from a directory containing a file called
 # DoxygenLayout.xml, doxygen will parse it automatically even if the LAYOUT_FILE
@@ -743,24 +826,43 @@ WARNINGS               = YES
 WARN_IF_UNDOCUMENTED   = YES
 
 # If the WARN_IF_DOC_ERROR tag is set to YES, doxygen will generate warnings for
-# potential errors in the documentation, such as not documenting some parameters
-# in a documented function, or documenting parameters that don't exist or using
-# markup commands wrongly.
+# potential errors in the documentation, such as documenting some parameters in
+# a documented function twice, or documenting parameters that don't exist or
+# using markup commands wrongly.
 # The default value is: YES.
 
 WARN_IF_DOC_ERROR      = YES
 
+# If WARN_IF_INCOMPLETE_DOC is set to YES, doxygen will warn about incomplete
+# function parameter documentation. If set to NO, doxygen will accept that some
+# parameters have no documentation without warning.
+# The default value is: YES.
+
+WARN_IF_INCOMPLETE_DOC = YES
+
 # This WARN_NO_PARAMDOC option can be enabled to get warnings for functions that
 # are documented, but have no documentation for their parameters or return
-# value. If set to NO, doxygen will only warn about wrong or incomplete
-# parameter documentation, but not about the absence of documentation. If
-# EXTRACT_ALL is set to YES then this flag will automatically be disabled.
+# value. If set to NO, doxygen will only warn about wrong parameter
+# documentation, but not about the absence of documentation. If EXTRACT_ALL is
+# set to YES then this flag will automatically be disabled. See also
+# WARN_IF_INCOMPLETE_DOC
 # The default value is: NO.
 
 WARN_NO_PARAMDOC       = NO
 
+# If WARN_IF_UNDOC_ENUM_VAL option is set to YES, doxygen will warn about
+# undocumented enumeration values. If set to NO, doxygen will accept
+# undocumented enumeration values. If EXTRACT_ALL is set to YES then this flag
+# will automatically be disabled.
+# The default value is: NO.
+
+WARN_IF_UNDOC_ENUM_VAL = NO
+
 # If the WARN_AS_ERROR tag is set to YES then doxygen will immediately stop when
-# a warning is encountered.
+# a warning is encountered. If the WARN_AS_ERROR tag is set to FAIL_ON_WARNINGS
+# then doxygen will continue running as if WARN_AS_ERROR tag is set to NO, but
+# at the end of the doxygen process doxygen will return with a non-zero status.
+# Possible values are: NO, YES and FAIL_ON_WARNINGS.
 # The default value is: NO.
 
 WARN_AS_ERROR          = NO
@@ -771,13 +873,27 @@ WARN_AS_ERROR          = NO
 # and the warning text. Optionally the format may contain $version, which will
 # be replaced by the version of the file (if it could be obtained via
 # FILE_VERSION_FILTER)
+# See also: WARN_LINE_FORMAT
 # The default value is: $file:$line: $text.
 
 WARN_FORMAT            = "$file:$line: $text"
 
+# In the $text part of the WARN_FORMAT command it is possible that a reference
+# to a more specific place is given. To make it easier to jump to this place
+# (outside of doxygen) the user can define a custom "cut" / "paste" string.
+# Example:
+# WARN_LINE_FORMAT = "'vi $file +$line'"
+# See also: WARN_FORMAT
+# The default value is: at line $line of file $file.
+
+WARN_LINE_FORMAT       = "at line $line of file $file"
+
 # The WARN_LOGFILE tag can be used to specify a file to which warning and error
 # messages should be written. If left blank the output is written to standard
-# error (stderr).
+# error (stderr). In case the file specified cannot be opened for writing the
+# warning and error messages are written to standard error. When as file - is
+# specified the warning and error messages are written to standard output
+# (stdout).
 
 WARN_LOGFILE           =
 
@@ -791,17 +907,28 @@ WARN_LOGFILE           =
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = @top_srcdir@/@doxygen_input_path@
+INPUT                  = ../src/liblzma/api
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
 # libiconv (or the iconv built into libc) for the transcoding. See the libiconv
-# documentation (see: https://www.gnu.org/software/libiconv/) for the list of
-# possible encodings.
+# documentation (see:
+# https://www.gnu.org/software/libiconv/) for the list of possible encodings.
+# See also: INPUT_FILE_ENCODING
 # The default value is: UTF-8.
 
 INPUT_ENCODING         = UTF-8
 
+# This tag can be used to specify the character encoding of the source files
+# that doxygen parses The INPUT_FILE_ENCODING tag can be used to specify
+# character encoding on a per file pattern basis. Doxygen will compare the file
+# name with each pattern and apply the encoding instead of the default
+# INPUT_ENCODING) if there is a match. The character encodings are a list of the
+# form: pattern=encoding (like *.php=ISO-8859-1). See cfg_input_encoding
+# "INPUT_ENCODING" for further information on supported encodings.
+
+INPUT_FILE_ENCODING    =
+
 # If the value of the INPUT tag contains directories, you can use the
 # FILE_PATTERNS tag to specify one or more wildcard patterns (like *.cpp and
 # *.h) to filter out the source-files in the directories.
@@ -810,15 +937,18 @@ INPUT_ENCODING         = UTF-8
 # need to set EXTENSION_MAPPING for the extension otherwise the files are not
 # read by doxygen.
 #
+# Note the list of default checked file patterns might differ from the list of
+# default file extension mappings.
+#
 # If left blank the following patterns are tested:*.c, *.cc, *.cxx, *.cpp,
 # *.c++, *.java, *.ii, *.ixx, *.ipp, *.i++, *.inl, *.idl, *.ddl, *.odl, *.h,
-# *.hh, *.hxx, *.hpp, *.h++, *.cs, *.d, *.php, *.php4, *.php5, *.phtml, *.inc,
-# *.m, *.markdown, *.md, *.mm, *.dox (to be provided as doxygen C comment),
-# *.doc (to be provided as doxygen C comment), *.txt (to be provided as doxygen
-# C comment), *.py, *.pyw, *.f90, *.f95, *.f03, *.f08, *.f, *.for, *.tcl, *.vhd,
+# *.hh, *.hxx, *.hpp, *.h++, *.l, *.cs, *.d, *.php, *.php4, *.php5, *.phtml,
+# *.inc, *.m, *.markdown, *.md, *.mm, *.dox (to be provided as doxygen C
+# comment), *.py, *.pyw, *.f90, *.f95, *.f03, *.f08, *.f18, *.f, *.for, *.vhd,
 # *.vhdl, *.ucf, *.qsf and *.ice.
 
-FILE_PATTERNS          = *.c *.h
+FILE_PATTERNS          = *.c \
+                         *.h
 
 # The RECURSIVE tag can be used to specify whether or not subdirectories should
 # be searched for input files as well.
@@ -855,7 +985,7 @@ EXCLUDE_PATTERNS       =
 # (namespaces, classes, functions, etc.) that should be excluded from the
 # output. The symbol name can be a fully qualified name, a word, or if the
 # wildcard * is used, a substring. Examples: ANamespace, AClass,
-# AClass::ANamespace, ANamespace::*Test
+# ANamespace::AClass, ANamespace::*Test
 #
 # Note that the wildcards are matched against the file with absolute path, so to
 # exclude all test directories use the pattern */test/*
@@ -903,6 +1033,11 @@ IMAGE_PATH             =
 # code is scanned, but not when the output code is generated. If lines are added
 # or removed, the anchors will not be placed correctly.
 #
+# Note that doxygen will use the data processed and written to standard output
+# for further processing, therefore nothing else, like debug statements or used
+# commands (so in case of a Windows batch file always use @echo OFF), should be
+# written to standard output.
+#
 # Note that for custom extensions or not directly supported extensions you also
 # need to set EXTENSION_MAPPING for the extension otherwise the files are not
 # properly processed by doxygen.
@@ -944,6 +1079,15 @@ FILTER_SOURCE_PATTERNS =
 
 USE_MDFILE_AS_MAINPAGE =
 
+# The Fortran standard specifies that for fixed formatted Fortran code all
+# characters from position 72 are to be considered as comment. A common
+# extension is to allow longer lines before the automatic comment starts. The
+# setting FORTRAN_COMMENT_AFTER will also make it possible that longer lines can
+# be processed before the automatic comment starts.
+# Minimum value: 7, maximum value: 10000, default value: 72.
+
+FORTRAN_COMMENT_AFTER  = 72
+
 #---------------------------------------------------------------------------
 # Configuration options related to source browsing
 #---------------------------------------------------------------------------
@@ -1030,35 +1174,6 @@ USE_HTAGS              = NO
 
 VERBATIM_HEADERS       = NO
 
-# If the CLANG_ASSISTED_PARSING tag is set to YES then doxygen will use the
-# clang parser (see: http://clang.llvm.org/) for more accurate parsing at the
-# cost of reduced performance. This can be particularly helpful with template
-# rich C++ code for which doxygen's built-in parser lacks the necessary type
-# information.
-# Note: The availability of this option depends on whether or not doxygen was
-# generated with the -Duse_libclang=ON option for CMake.
-# The default value is: NO.
-
-CLANG_ASSISTED_PARSING = NO
-
-# If clang assisted parsing is enabled you can provide the compiler with command
-# line options that you would normally use when invoking the compiler. Note that
-# the include paths will already be set by doxygen for the files and directories
-# specified with INPUT and INCLUDE_PATH.
-# This tag requires that the tag CLANG_ASSISTED_PARSING is set to YES.
-
-CLANG_OPTIONS          =
-
-# If clang assisted parsing is enabled you can provide the clang parser with the
-# path to the compilation database (see:
-# http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html) used when the files
-# were built. This is equivalent to specifying the "-p" option to a clang tool,
-# such as clang-check. These options will then be passed to the parser.
-# Note: The availability of this option depends on whether or not doxygen was
-# generated with the -Duse_libclang=ON option for CMake.
-
-CLANG_DATABASE_PATH    =
-
 #---------------------------------------------------------------------------
 # Configuration options related to the alphabetical class index
 #---------------------------------------------------------------------------
@@ -1070,17 +1185,11 @@ CLANG_DATABASE_PATH    =
 
 ALPHABETICAL_INDEX     = NO
 
-# The COLS_IN_ALPHA_INDEX tag can be used to specify the number of columns in
-# which the alphabetical index list will be split.
-# Minimum value: 1, maximum value: 20, default value: 5.
-# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
-
-COLS_IN_ALPHA_INDEX    = 5
-
-# In case all classes in a project start with a common prefix, all classes will
-# be put under the same header in the alphabetical index. The IGNORE_PREFIX tag
-# can be used to specify a prefix (or a list of prefixes) that should be ignored
-# while generating the index headers.
+# The IGNORE_PREFIX tag can be used to specify a prefix (or a list of prefixes)
+# that should be ignored while generating the index headers. The IGNORE_PREFIX
+# tag works for classes, function and member names. The entity will be placed in
+# the alphabetical list under the first letter of the entity name that remains
+# after removing the prefix.
 # This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
 
 IGNORE_PREFIX          =
@@ -1100,7 +1209,7 @@ GENERATE_HTML          = YES
 # The default directory is: html.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_OUTPUT            = html
+HTML_OUTPUT            = liblzma
 
 # The HTML_FILE_EXTENSION tag can be used to specify the file extension for each
 # generated HTML page (for example: .htm, .php, .asp).
@@ -1159,7 +1268,12 @@ HTML_STYLESHEET        =
 # Doxygen will copy the style sheet files to the output directory.
 # Note: The order of the extra style sheet files is of importance (e.g. the last
 # style sheet in the list overrules the setting of the previous ones in the
-# list). For an example see the documentation.
+# list).
+# Note: Since the styling of scrollbars can currently not be overruled in
+# Webkit/Chromium, the styling will be left out of the default doxygen.css if
+# one or more extra stylesheets have been specified. So if scrollbar
+# customization is desired it has to be added explicitly. For an example see the
+# documentation.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
 HTML_EXTRA_STYLESHEET  =
@@ -1174,24 +1288,37 @@ HTML_EXTRA_STYLESHEET  =
 
 HTML_EXTRA_FILES       =
 
+# The HTML_COLORSTYLE tag can be used to specify if the generated HTML output
+# should be rendered with a dark or light theme.
+# Possible values are: LIGHT always generate light mode output, DARK always
+# generate dark mode output, AUTO_LIGHT automatically set the mode according to
+# the user preference, use light mode if no preference is set (the default),
+# AUTO_DARK automatically set the mode according to the user preference, use
+# dark mode if no preference is set and TOGGLE allow to user to switch between
+# light and dark mode via a button.
+# The default value is: AUTO_LIGHT.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE        = AUTO_LIGHT
+
 # The HTML_COLORSTYLE_HUE tag controls the color of the HTML output. Doxygen
 # will adjust the colors in the style sheet and background images according to
-# this color. Hue is specified as an angle on a colorwheel, see
+# this color. Hue is specified as an angle on a color-wheel, see
 # https://en.wikipedia.org/wiki/Hue for more information. For instance the value
 # 0 represents red, 60 is yellow, 120 is green, 180 is cyan, 240 is blue, 300
 # purple, and 360 is red again.
 # Minimum value: 0, maximum value: 359, default value: 220.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_COLORSTYLE_HUE    = 220
+HTML_COLORSTYLE_HUE    = 210
 
 # The HTML_COLORSTYLE_SAT tag controls the purity (or saturation) of the colors
-# in the HTML output. For a value of 0 the output will use grayscales only. A
+# in the HTML output. For a value of 0 the output will use gray-scales only. A
 # value of 255 will produce the most vivid colors.
 # Minimum value: 0, maximum value: 255, default value: 100.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_COLORSTYLE_SAT    = 100
+HTML_COLORSTYLE_SAT    = 180
 
 # The HTML_COLORSTYLE_GAMMA tag controls the gamma correction applied to the
 # luminance component of the colors in the HTML output. Values below 100
@@ -1202,7 +1329,7 @@ HTML_COLORSTYLE_SAT    = 100
 # Minimum value: 40, maximum value: 240, default value: 80.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_COLORSTYLE_GAMMA  = 80
+HTML_COLORSTYLE_GAMMA  = 110
 
 # If the HTML_TIMESTAMP tag is set to YES then the footer of each generated HTML
 # page will contain the date and time when the page was generated. Setting this
@@ -1222,7 +1349,7 @@ HTML_TIMESTAMP         = NO
 # The default value is: YES.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_DYNAMIC_MENUS     = YES
+HTML_DYNAMIC_MENUS     = NO
 
 # If the HTML_DYNAMIC_SECTIONS tag is set to YES then the generated HTML
 # documentation will contain sections that can be hidden and shown after the
@@ -1247,10 +1374,11 @@ HTML_INDEX_NUM_ENTRIES = 100
 
 # If the GENERATE_DOCSET tag is set to YES, additional index files will be
 # generated that can be used as input for Apple's Xcode 3 integrated development
-# environment (see: https://developer.apple.com/xcode/), introduced with OSX
-# 10.5 (Leopard). To create a documentation set, doxygen will generate a
-# Makefile in the HTML output directory. Running make will produce the docset in
-# that directory and running make install will install the docset in
+# environment (see:
+# https://developer.apple.com/xcode/), introduced with OSX 10.5 (Leopard). To
+# create a documentation set, doxygen will generate a Makefile in the HTML
+# output directory. Running make will produce the docset in that directory and
+# running make install will install the docset in
 # ~/Library/Developer/Shared/Documentation/DocSets so that Xcode will find it at
 # startup. See https://developer.apple.com/library/archive/featuredarticles/Doxy
 # genXcode/_index.html for more information.
@@ -1267,6 +1395,13 @@ GENERATE_DOCSET        = NO
 
 DOCSET_FEEDNAME        = "Doxygen generated docs"
 
+# This tag determines the URL of the docset feed. A documentation feed provides
+# an umbrella under which multiple documentation sets from a single provider
+# (such as a company or product suite) can be grouped.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_FEEDURL         =
+
 # This tag specifies a string that should uniquely identify the documentation
 # set bundle. This should be a reverse domain-name style string, e.g.
 # com.mycompany.MyDocSet. Doxygen will append .docset to the name.
@@ -1292,8 +1427,12 @@ DOCSET_PUBLISHER_NAME  = Publisher
 # If the GENERATE_HTMLHELP tag is set to YES then doxygen generates three
 # additional HTML index files: index.hhp, index.hhc, and index.hhk. The
 # index.hhp is a project file that can be read by Microsoft's HTML Help Workshop
-# (see: https://www.microsoft.com/en-us/download/details.aspx?id=21138) on
-# Windows.
+# on Windows. In the beginning of 2021 Microsoft took the original page, with
+# a.o. the download links, offline the HTML help workshop was already many years
+# in maintenance mode). You can download the HTML help workshop from the web
+# archives at Installation executable (see:
+# http://web.archive.org/web/20160201063255/http://download.microsoft.com/downlo
+# ad/0/A/9/0A939EF6-E31C-430F-A3DF-DFAE7960D564/htmlhelp.exe).
 #
 # The HTML Help Workshop contains a compiler that can convert all HTML output
 # generated by doxygen into a single compiled HTML file (.chm). Compiled HTML
@@ -1323,7 +1462,7 @@ CHM_FILE               =
 HHC_LOCATION           =
 
 # The GENERATE_CHI flag controls if a separate .chi index file is generated
-# (YES) or that it should be included in the master .chm file (NO).
+# (YES) or that it should be included in the main .chm file (NO).
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTMLHELP is set to YES.
 
@@ -1368,7 +1507,8 @@ QCH_FILE               =
 
 # The QHP_NAMESPACE tag specifies the namespace to use when generating Qt Help
 # Project output. For more information please see Qt Help Project / Namespace
-# (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#namespace).
+# (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#namespace).
 # The default value is: org.doxygen.Project.
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
@@ -1376,8 +1516,8 @@ QHP_NAMESPACE          = org.doxygen.Project
 
 # The QHP_VIRTUAL_FOLDER tag specifies the namespace to use when generating Qt
 # Help Project output. For more information please see Qt Help Project / Virtual
-# Folders (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#virtual-
-# folders).
+# Folders (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#virtual-folders).
 # The default value is: doc.
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
@@ -1385,16 +1525,16 @@ QHP_VIRTUAL_FOLDER     = doc
 
 # If the QHP_CUST_FILTER_NAME tag is set, it specifies the name of a custom
 # filter to add. For more information please see Qt Help Project / Custom
-# Filters (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-
-# filters).
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
 QHP_CUST_FILTER_NAME   =
 
 # The QHP_CUST_FILTER_ATTRS tag specifies the list of the attributes of the
 # custom filter to add. For more information please see Qt Help Project / Custom
-# Filters (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-
-# filters).
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
 QHP_CUST_FILTER_ATTRS  =
@@ -1406,9 +1546,9 @@ QHP_CUST_FILTER_ATTRS  =
 
 QHP_SECT_FILTER_ATTRS  =
 
-# The QHG_LOCATION tag can be used to specify the location of Qt's
-# qhelpgenerator. If non-empty doxygen will try to run qhelpgenerator on the
-# generated .qhp file.
+# The QHG_LOCATION tag can be used to specify the location (absolute path
+# including file name) of Qt's qhelpgenerator. If non-empty doxygen will try to
+# run qhelpgenerator on the generated .qhp file.
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
 QHG_LOCATION           =
@@ -1451,16 +1591,28 @@ DISABLE_INDEX          = NO
 # to work a browser that supports JavaScript, DHTML, CSS and frames is required
 # (i.e. any modern browser). Windows users are probably better off using the
 # HTML help feature. Via custom style sheets (see HTML_EXTRA_STYLESHEET) one can
-# further fine-tune the look of the index. As an example, the default style
-# sheet generated by doxygen has an example that shows how to put an image at
-# the root of the tree instead of the PROJECT_NAME. Since the tree basically has
-# the same information as the tab index, you could consider setting
-# DISABLE_INDEX to YES when enabling this option.
+# further fine tune the look of the index (see "Fine-tuning the output"). As an
+# example, the default style sheet generated by doxygen has an example that
+# shows how to put an image at the root of the tree instead of the PROJECT_NAME.
+# Since the tree basically has the same information as the tab index, you could
+# consider setting DISABLE_INDEX to YES when enabling this option.
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
 GENERATE_TREEVIEW      = NO
 
+# When both GENERATE_TREEVIEW and DISABLE_INDEX are set to YES, then the
+# FULL_SIDEBAR option determines if the side bar is limited to only the treeview
+# area (value NO) or if it should extend to the full height of the window (value
+# YES). Setting this to YES gives a layout similar to
+# https://docs.readthedocs.io with more room for contents, but less room for the
+# project logo, title, and description. If either GENERATE_TREEVIEW or
+# DISABLE_INDEX is set to NO, this option has no effect.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FULL_SIDEBAR           = NO
+
 # The ENUM_VALUES_PER_LINE tag can be used to set the number of enum values that
 # doxygen will group on one line in the generated HTML documentation.
 #
@@ -1485,6 +1637,24 @@ TREEVIEW_WIDTH         = 250
 
 EXT_LINKS_IN_WINDOW    = NO
 
+# If the OBFUSCATE_EMAILS tag is set to YES, doxygen will obfuscate email
+# addresses.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+OBFUSCATE_EMAILS       = YES
+
+# If the HTML_FORMULA_FORMAT option is set to svg, doxygen will use the pdf2svg
+# tool (see https://github.com/dawbarton/pdf2svg) or inkscape (see
+# https://inkscape.org) to generate formulas as SVG images instead of PNGs for
+# the HTML output. These images will generally look nicer at scaled resolutions.
+# Possible values are: png (the default) and svg (looks nicer but requires the
+# pdf2svg or inkscape tool).
+# The default value is: png.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FORMULA_FORMAT    = png
+
 # Use this tag to change the font size of LaTeX formulas included as images in
 # the HTML documentation. When you change the font size after a successful
 # doxygen run you need to manually remove any form_*.png images from the HTML
@@ -1494,17 +1664,6 @@ EXT_LINKS_IN_WINDOW    = NO
 
 FORMULA_FONTSIZE       = 10
 
-# Use the FORMULA_TRANSPARENT tag to determine whether or not the images
-# generated for formulas are transparent PNGs. Transparent PNGs are not
-# supported properly for IE 6.0, but are supported on all modern browsers.
-#
-# Note that when changing this option you need to delete any form_*.png files in
-# the HTML output directory before the changes have effect.
-# The default value is: YES.
-# This tag requires that the tag GENERATE_HTML is set to YES.
-
-FORMULA_TRANSPARENT    = YES
-
 # The FORMULA_MACROFILE can contain LaTeX \newcommand and \renewcommand commands
 # to create new LaTeX commands to be used in formulas as building blocks. See
 # the section "Including formulas" for details.
@@ -1522,11 +1681,29 @@ FORMULA_MACROFILE      =
 
 USE_MATHJAX            = NO
 
+# With MATHJAX_VERSION it is possible to specify the MathJax version to be used.
+# Note that the different versions of MathJax have different requirements with
+# regards to the different settings, so it is possible that also other MathJax
+# settings have to be changed when switching between the different MathJax
+# versions.
+# Possible values are: MathJax_2 and MathJax_3.
+# The default value is: MathJax_2.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_VERSION        = MathJax_2
+
 # When MathJax is enabled you can set the default output format to be used for
-# the MathJax output. See the MathJax site (see:
-# http://docs.mathjax.org/en/latest/output.html) for more details.
+# the MathJax output. For more details about the output format see MathJax
+# version 2 (see:
+# http://docs.mathjax.org/en/v2.7-latest/output.html) and MathJax version 3
+# (see:
+# http://docs.mathjax.org/en/latest/web/components/output.html).
 # Possible values are: HTML-CSS (which is slower, but has the best
-# compatibility), NativeMML (i.e. MathML) and SVG.
+# compatibility. This is the name for Mathjax version 2, for MathJax version 3
+# this will be translated into chtml), NativeMML (i.e. MathML. Only supported
+# for NathJax 2. For MathJax version 3 chtml will be used instead.), chtml (This
+# is the name for Mathjax version 3, for MathJax version 2 this will be
+# translated into HTML-CSS) and SVG.
 # The default value is: HTML-CSS.
 # This tag requires that the tag USE_MATHJAX is set to YES.
 
@@ -1539,22 +1716,29 @@ MATHJAX_FORMAT         = HTML-CSS
 # MATHJAX_RELPATH should be ../mathjax. The default value points to the MathJax
 # Content Delivery Network so you can quickly see the result without installing
 # MathJax. However, it is strongly recommended to install a local copy of
-# MathJax from https://www.mathjax.org before deployment.
-# The default value is: https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/.
+# MathJax from https://www.mathjax.org before deployment. The default value is:
+# - in case of MathJax version 2: https://cdn.jsdelivr.net/npm/mathjax@2
+# - in case of MathJax version 3: https://cdn.jsdelivr.net/npm/mathjax@3
 # This tag requires that the tag USE_MATHJAX is set to YES.
 
 MATHJAX_RELPATH        = https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/
 
 # The MATHJAX_EXTENSIONS tag can be used to specify one or more MathJax
 # extension names that should be enabled during MathJax rendering. For example
+# for MathJax version 2 (see
+# https://docs.mathjax.org/en/v2.7-latest/tex.html#tex-and-latex-extensions):
 # MATHJAX_EXTENSIONS = TeX/AMSmath TeX/AMSsymbols
+# For example for MathJax version 3 (see
+# http://docs.mathjax.org/en/latest/input/tex/extensions/index.html):
+# MATHJAX_EXTENSIONS = ams
 # This tag requires that the tag USE_MATHJAX is set to YES.
 
 MATHJAX_EXTENSIONS     =
 
 # The MATHJAX_CODEFILE tag can be used to specify a file with javascript pieces
 # of code that will be used on startup of the MathJax code. See the MathJax site
-# (see: http://docs.mathjax.org/en/latest/output.html) for more details. For an
+# (see:
+# http://docs.mathjax.org/en/v2.7-latest/output.html) for more details. For an
 # example see the documentation.
 # This tag requires that the tag USE_MATHJAX is set to YES.
 
@@ -1601,7 +1785,8 @@ SERVER_BASED_SEARCH    = NO
 #
 # Doxygen ships with an example indexer (doxyindexer) and search engine
 # (doxysearch.cgi) which are based on the open source search engine library
-# Xapian (see: https://xapian.org/).
+# Xapian (see:
+# https://xapian.org/).
 #
 # See the section "External Indexing and Searching" for details.
 # The default value is: NO.
@@ -1614,8 +1799,9 @@ EXTERNAL_SEARCH        = NO
 #
 # Doxygen ships with an example indexer (doxyindexer) and search engine
 # (doxysearch.cgi) which are based on the open source search engine library
-# Xapian (see: https://xapian.org/). See the section "External Indexing and
-# Searching" for details.
+# Xapian (see:
+# https://xapian.org/). See the section "External Indexing and Searching" for
+# details.
 # This tag requires that the tag SEARCHENGINE is set to YES.
 
 SEARCHENGINE_URL       =
@@ -1710,7 +1896,7 @@ COMPACT_LATEX          = NO
 # The default value is: a4.
 # This tag requires that the tag GENERATE_LATEX is set to YES.
 
-PAPER_TYPE             = a4wide
+PAPER_TYPE             = a4
 
 # The EXTRA_PACKAGES tag can be used to specify one or more LaTeX package names
 # that should be included in the LaTeX output. The package can be specified just
@@ -1724,29 +1910,31 @@ PAPER_TYPE             = a4wide
 
 EXTRA_PACKAGES         =
 
-# The LATEX_HEADER tag can be used to specify a personal LaTeX header for the
-# generated LaTeX document. The header should contain everything until the first
-# chapter. If it is left blank doxygen will generate a standard header. See
-# section "Doxygen usage" for information on how to let doxygen write the
-# default header to a separate file.
+# The LATEX_HEADER tag can be used to specify a user-defined LaTeX header for
+# the generated LaTeX document. The header should contain everything until the
+# first chapter. If it is left blank doxygen will generate a standard header. It
+# is highly recommended to start with a default header using
+# doxygen -w latex new_header.tex new_footer.tex new_stylesheet.sty
+# and then modify the file new_header.tex. See also section "Doxygen usage" for
+# information on how to generate the default header that doxygen normally uses.
 #
-# Note: Only use a user-defined header if you know what you are doing! The
-# following commands have a special meaning inside the header: $title,
-# $datetime, $date, $doxygenversion, $projectname, $projectnumber,
-# $projectbrief, $projectlogo. Doxygen will replace $title with the empty
-# string, for the replacement values of the other commands the user is referred
-# to HTML_HEADER.
+# Note: Only use a user-defined header if you know what you are doing!
+# Note: The header is subject to change so you typically have to regenerate the
+# default header when upgrading to a newer version of doxygen. The following
+# commands have a special meaning inside the header (and footer): For a
+# description of the possible markers and block names see the documentation.
 # This tag requires that the tag GENERATE_LATEX is set to YES.
 
 LATEX_HEADER           =
 
-# The LATEX_FOOTER tag can be used to specify a personal LaTeX footer for the
-# generated LaTeX document. The footer should contain everything after the last
-# chapter. If it is left blank doxygen will generate a standard footer. See
+# The LATEX_FOOTER tag can be used to specify a user-defined LaTeX footer for
+# the generated LaTeX document. The footer should contain everything after the
+# last chapter. If it is left blank doxygen will generate a standard footer. See
 # LATEX_HEADER for more information on how to generate a default footer and what
-# special commands can be used inside the footer.
-#
-# Note: Only use a user-defined footer if you know what you are doing!
+# special commands can be used inside the footer. See also section "Doxygen
+# usage" for information on how to generate the default footer that doxygen
+# normally uses. Note: Only use a user-defined footer if you know what you are
+# doing!
 # This tag requires that the tag GENERATE_LATEX is set to YES.
 
 LATEX_FOOTER           =
@@ -1779,9 +1967,11 @@ LATEX_EXTRA_FILES      =
 
 PDF_HYPERLINKS         = NO
 
-# If the USE_PDFLATEX tag is set to YES, doxygen will use pdflatex to generate
-# the PDF file directly from the LaTeX files. Set this option to YES, to get a
-# higher quality PDF documentation.
+# If the USE_PDFLATEX tag is set to YES, doxygen will use the engine as
+# specified with LATEX_CMD_NAME to generate the PDF file directly from the LaTeX
+# files. Set this option to YES, to get a higher quality PDF documentation.
+#
+# See also section LATEX_CMD_NAME for selecting the engine.
 # The default value is: YES.
 # This tag requires that the tag GENERATE_LATEX is set to YES.
 
@@ -1789,8 +1979,7 @@ USE_PDFLATEX           = YES
 
 # If the LATEX_BATCHMODE tag is set to YES, doxygen will add the \batchmode
 # command to the generated LaTeX files. This will instruct LaTeX to keep running
-# if errors occur, instead of asking the user for help. This option is also used
-# when generating formulas in HTML.
+# if errors occur, instead of asking the user for help.
 # The default value is: NO.
 # This tag requires that the tag GENERATE_LATEX is set to YES.
 
@@ -1803,16 +1992,6 @@ LATEX_BATCHMODE        = NO
 
 LATEX_HIDE_INDICES     = NO
 
-# If the LATEX_SOURCE_CODE tag is set to YES then doxygen will include source
-# code with syntax highlighting in the LaTeX output.
-#
-# Note that which sources are shown also depends on other settings such as
-# SOURCE_BROWSER.
-# The default value is: NO.
-# This tag requires that the tag GENERATE_LATEX is set to YES.
-
-LATEX_SOURCE_CODE      = NO
-
 # The LATEX_BIB_STYLE tag can be used to specify the style to use for the
 # bibliography, e.g. plainnat, or ieeetr. See
 # https://en.wikipedia.org/wiki/BibTeX and \cite for more info.
@@ -1893,16 +2072,6 @@ RTF_STYLESHEET_FILE    =
 
 RTF_EXTENSIONS_FILE    =
 
-# If the RTF_SOURCE_CODE tag is set to YES then doxygen will include source code
-# with syntax highlighting in the RTF output.
-#
-# Note that which sources are shown also depends on other settings such as
-# SOURCE_BROWSER.
-# The default value is: NO.
-# This tag requires that the tag GENERATE_RTF is set to YES.
-
-RTF_SOURCE_CODE        = NO
-
 #---------------------------------------------------------------------------
 # Configuration options related to the man page output
 #---------------------------------------------------------------------------
@@ -1999,15 +2168,6 @@ GENERATE_DOCBOOK       = NO
 
 DOCBOOK_OUTPUT         = docbook
 
-# If the DOCBOOK_PROGRAMLISTING tag is set to YES, doxygen will include the
-# program listings (including syntax highlighting and cross-referencing
-# information) to the DOCBOOK output. Note that enabling this will significantly
-# increase the size of the DOCBOOK output.
-# The default value is: NO.
-# This tag requires that the tag GENERATE_DOCBOOK is set to YES.
-
-DOCBOOK_PROGRAMLISTING = NO
-
 #---------------------------------------------------------------------------
 # Configuration options for the AutoGen Definitions output
 #---------------------------------------------------------------------------
@@ -2094,7 +2254,8 @@ SEARCH_INCLUDES        = YES
 
 # The INCLUDE_PATH tag can be used to specify one or more directories that
 # contain include files that are not input files but should be processed by the
-# preprocessor.
+# preprocessor. Note that the INCLUDE_PATH is not recursive, so the setting of
+# RECURSIVE has no effect here.
 # This tag requires that the tag SEARCH_INCLUDES is set to YES.
 
 INCLUDE_PATH           =
@@ -2188,15 +2349,6 @@ EXTERNAL_PAGES         = YES
 # Configuration options related to the dot tool
 #---------------------------------------------------------------------------
 
-# If the CLASS_DIAGRAMS tag is set to YES, doxygen will generate a class diagram
-# (in HTML and LaTeX) for classes with base or super classes. Setting the tag to
-# NO turns the diagrams off. Note that this option also works with HAVE_DOT
-# disabled, but it is recommended to install and use dot, since it yields more
-# powerful graphs.
-# The default value is: YES.
-
-CLASS_DIAGRAMS         = YES
-
 # You can include diagrams made with dia in doxygen documentation. Doxygen will
 # then run dia to produce the diagram and insert it in the documentation. The
 # DIA_PATH tag allows you to specify the directory where the dia binary resides.
@@ -2215,7 +2367,7 @@ HIDE_UNDOC_RELATIONS   = YES
 # http://www.graphviz.org/), a graph visualization toolkit from AT&T and Lucent
 # Bell Labs. The other options in this section have no effect if this option is
 # set to NO
-# The default value is: YES.
+# The default value is: NO.
 
 HAVE_DOT               = NO
 
@@ -2229,35 +2381,50 @@ HAVE_DOT               = NO
 
 DOT_NUM_THREADS        = 0
 
-# When you want a differently looking font in the dot files that doxygen
-# generates you can specify the font name using DOT_FONTNAME. You need to make
-# sure dot is able to find the font, which can be done by putting it in a
-# standard location or by setting the DOTFONTPATH environment variable or by
-# setting DOT_FONTPATH to the directory containing the font.
-# The default value is: Helvetica.
+# DOT_COMMON_ATTR is common attributes for nodes, edges and labels of
+# subgraphs. When you want a differently looking font in the dot files that
+# doxygen generates you can specify fontname, fontcolor and fontsize attributes.
+# For details please see <a href=https://graphviz.org/doc/info/attrs.html>Node,
+# Edge and Graph Attributes specification</a> You need to make sure dot is able
+# to find the font, which can be done by putting it in a standard location or by
+# setting the DOTFONTPATH environment variable or by setting DOT_FONTPATH to the
+# directory containing the font. Default graphviz fontsize is 14.
+# The default value is: fontname=Helvetica,fontsize=10.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_COMMON_ATTR        = "fontname=Helvetica,fontsize=10"
+
+# DOT_EDGE_ATTR is concatenated with DOT_COMMON_ATTR. For elegant style you can
+# add 'arrowhead=open, arrowtail=open, arrowsize=0.5'. <a
+# href=https://graphviz.org/doc/info/arrows.html>Complete documentation about
+# arrows shapes.</a>
+# The default value is: labelfontname=Helvetica,labelfontsize=10.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_FONTNAME           = Helvetica
+DOT_EDGE_ATTR          = "labelfontname=Helvetica,labelfontsize=10"
 
-# The DOT_FONTSIZE tag can be used to set the size (in points) of the font of
-# dot graphs.
-# Minimum value: 4, maximum value: 24, default value: 10.
+# DOT_NODE_ATTR is concatenated with DOT_COMMON_ATTR. For view without boxes
+# around nodes set 'shape=plain' or 'shape=plaintext' <a
+# href=https://www.graphviz.org/doc/info/shapes.html>Shapes specification</a>
+# The default value is: shape=box,height=0.2,width=0.4.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_FONTSIZE           = 10
+DOT_NODE_ATTR          = "shape=box,height=0.2,width=0.4"
 
-# By default doxygen will tell dot to use the default font as specified with
-# DOT_FONTNAME. If you specify a different font using DOT_FONTNAME you can set
-# the path where dot can find it using this tag.
+# You can set the path where dot can find font specified with fontname in
+# DOT_COMMON_ATTR and others dot attributes.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
 DOT_FONTPATH           =
 
-# If the CLASS_GRAPH tag is set to YES then doxygen will generate a graph for
-# each documented class showing the direct and indirect inheritance relations.
-# Setting this tag to YES will force the CLASS_DIAGRAMS tag to NO.
+# If the CLASS_GRAPH tag is set to YES (or GRAPH) then doxygen will generate a
+# graph for each documented class showing the direct and indirect inheritance
+# relations. In case HAVE_DOT is set as well dot will be used to draw the graph,
+# otherwise the built-in generator will be used. If the CLASS_GRAPH tag is set
+# to TEXT the direct and indirect inheritance relations will be shown as texts /
+# links.
+# Possible values are: NO, YES, TEXT and GRAPH.
 # The default value is: YES.
-# This tag requires that the tag HAVE_DOT is set to YES.
 
 CLASS_GRAPH            = YES
 
@@ -2271,7 +2438,8 @@ CLASS_GRAPH            = YES
 COLLABORATION_GRAPH    = YES
 
 # If the GROUP_GRAPHS tag is set to YES then doxygen will generate a graph for
-# groups, showing the direct groups dependencies.
+# groups, showing the direct groups dependencies. See also the chapter Grouping
+# in the manual.
 # The default value is: YES.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
@@ -2294,10 +2462,32 @@ UML_LOOK               = NO
 # but if the number exceeds 15, the total amount of fields shown is limited to
 # 10.
 # Minimum value: 0, maximum value: 100, default value: 10.
-# This tag requires that the tag HAVE_DOT is set to YES.
+# This tag requires that the tag UML_LOOK is set to YES.
 
 UML_LIMIT_NUM_FIELDS   = 10
 
+# If the DOT_UML_DETAILS tag is set to NO, doxygen will show attributes and
+# methods without types and arguments in the UML graphs. If the DOT_UML_DETAILS
+# tag is set to YES, doxygen will add type and arguments for attributes and
+# methods in the UML graphs. If the DOT_UML_DETAILS tag is set to NONE, doxygen
+# will not generate fields with class member information in the UML graphs. The
+# class diagrams will look similar to the default class diagrams but using UML
+# notation for the relationships.
+# Possible values are: NO, YES and NONE.
+# The default value is: NO.
+# This tag requires that the tag UML_LOOK is set to YES.
+
+DOT_UML_DETAILS        = NO
+
+# The DOT_WRAP_THRESHOLD tag can be used to set the maximum number of characters
+# to display on a single line. If the actual line length exceeds this threshold
+# significantly it will wrapped across multiple lines. Some heuristics are apply
+# to avoid ugly line breaks.
+# Minimum value: 0, maximum value: 1000, default value: 17.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_WRAP_THRESHOLD     = 17
+
 # If the TEMPLATE_RELATIONS tag is set to YES then the inheritance and
 # collaboration graphs will show the relations between templates and their
 # instances.
@@ -2364,6 +2554,13 @@ GRAPHICAL_HIERARCHY    = YES
 
 DIRECTORY_GRAPH        = YES
 
+# The DIR_GRAPH_MAX_DEPTH tag can be used to limit the maximum number of levels
+# of child directories generated in directory dependency graphs by dot.
+# Minimum value: 1, maximum value: 25, default value: 1.
+# This tag requires that the tag DIRECTORY_GRAPH is set to YES.
+
+DIR_GRAPH_MAX_DEPTH    = 1
+
 # The DOT_IMAGE_FORMAT tag can be used to set the image format of the images
 # generated by dot. For an explanation of the image formats see the section
 # output formats in the documentation of the dot tool (Graphviz (see:
@@ -2371,9 +2568,7 @@ DIRECTORY_GRAPH        = YES
 # Note: If you choose svg you need to set HTML_FILE_EXTENSION to xhtml in order
 # to make the SVG files visible in IE 9+ (other browsers do not have this
 # requirement).
-# Possible values are: png, png:cairo, png:cairo:cairo, png:cairo:gd, png:gd,
-# png:gd:gd, jpg, jpg:cairo, jpg:cairo:gd, jpg:gd, jpg:gd:gd, gif, gif:cairo,
-# gif:cairo:gd, gif:gd, gif:gd:gd, svg, png:gd, png:gd:gd, png:cairo,
+# Possible values are: png, jpg, gif, svg, png:gd, png:gd:gd, png:cairo,
 # png:cairo:gd, png:cairo:cairo, png:cairo:gdiplus, png:gdiplus and
 # png:gdiplus:gdiplus.
 # The default value is: png.
@@ -2419,10 +2614,10 @@ MSCFILE_DIRS           =
 DIAFILE_DIRS           =
 
 # When using plantuml, the PLANTUML_JAR_PATH tag should be used to specify the
-# path where java can find the plantuml.jar file. If left blank, it is assumed
-# PlantUML is not used or called during a preprocessing step. Doxygen will
-# generate a warning when it encounters a \startuml command in this case and
-# will not generate output for the diagram.
+# path where java can find the plantuml.jar file or to the filename of jar file
+# to be used. If left blank, it is assumed PlantUML is not used or called during
+# a preprocessing step. Doxygen will generate a warning when it encounters a
+# \startuml command in this case and will not generate output for the diagram.
 
 PLANTUML_JAR_PATH      =
 
@@ -2460,18 +2655,6 @@ DOT_GRAPH_MAX_NODES    = 50
 
 MAX_DOT_GRAPH_DEPTH    = 0
 
-# Set the DOT_TRANSPARENT tag to YES to generate images with a transparent
-# background. This is disabled by default, because dot on Windows does not seem
-# to support this out of the box.
-#
-# Warning: Depending on the platform used, enabling this option may lead to
-# badly anti-aliased labels on the edges of a graph (i.e. they become hard to
-# read).
-# The default value is: NO.
-# This tag requires that the tag HAVE_DOT is set to YES.
-
-DOT_TRANSPARENT        = NO
-
 # Set the DOT_MULTI_TARGETS tag to YES to allow dot to generate multiple output
 # files in one run (i.e. multiple -o and -T options on the command line). This
 # makes dot run faster, but since only newer versions of dot (>1.8.10) support
@@ -2484,14 +2667,18 @@ DOT_MULTI_TARGETS      = NO
 # If the GENERATE_LEGEND tag is set to YES doxygen will generate a legend page
 # explaining the meaning of the various boxes and arrows in the dot generated
 # graphs.
+# Note: This tag requires that UML_LOOK isn't set, i.e. the doxygen internal
+# graphical representation for inheritance and collaboration diagrams is used.
 # The default value is: YES.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
 GENERATE_LEGEND        = YES
 
-# If the DOT_CLEANUP tag is set to YES, doxygen will remove the intermediate dot
+# If the DOT_CLEANUP tag is set to YES, doxygen will remove the intermediate
 # files that are used to generate the various graphs.
+#
+# Note: This setting is not only used for dot files but also for msc temporary
+# files.
 # The default value is: YES.
-# This tag requires that the tag HAVE_DOT is set to YES.
 
 DOT_CLEANUP            = YES