Add doxygen config and update formatting and doc comments

5 files changed, 3207 insertions, 1282 deletions

diff --git a/.gitignore b/.gitignore
index 179b224..0f7e72c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
+Makefile.config.override
 build-*
-
+docs/html
+*~
diff --git a/README b/README
new file mode 100644
index 0000000..498ee46
--- /dev/null
+++ b/README
@@ -0,0 +1,36 @@
+libnsgif - Decoding GIF files
+=============================
+
+The functions provided by this library allow for efficient progressive
+GIF decoding. Whilst the initialisation does not ensure that there is
+sufficient image data to complete the entire frame, it does ensure
+that the information provided is valid. Any subsequent attempts to
+decode an initialised GIF are guaranteed to succeed, and any bytes of
+the image not present are assumed to be totally transparent.
+
+To begin decoding a GIF, the 'gif' structure must be initialised with
+the 'gif_data' and 'buffer_size' set to their initial values. The
+'buffer_position' should initially be 0, and will be internally
+updated as the decoding commences. The caller should then repeatedly
+call gif_initialise() with the structure until the function returns 1,
+or no more data is avaliable.
+
+Once the initialisation has begun, the decoder completes the variables
+'frame_count' and 'frame_count_partial'. The former being the total
+number of frames that have been successfully initialised, and the
+latter being the number of frames that a partial amount of data is
+available for. This assists the caller in managing the animation
+whilst decoding is continuing.
+
+To decode a frame, the caller must use gif_decode_frame() which
+updates the current 'frame_image' to reflect the desired frame. The
+required 'disposal_method' is also updated to reflect how the frame
+should be plotted. The caller must not assume that the current
+'frame_image' will be valid between calls if initialisation is still
+occuring, and should either always request that the frame is decoded
+(no processing will occur if the 'decoded_frame' has not been
+invalidated by initialisation) or perform the check itself.
+
+It should be noted that gif_finalise() should always be called, even
+if no frames were initialised.  Additionally, it is the responsibility
+of the caller to free 'gif_data'.
diff --git a/docs/Doxyfile b/docs/Doxyfile
new file mode 100644
index 0000000..fbbf523
--- /dev/null
+++ b/docs/Doxyfile
@@ -0,0 +1,1792 @@
+# Doxyfile 1.8.1.2
+
+# This file describes the settings to be used by the documentation system
+# doxygen (www.doxygen.org) for a project.
+#
+# All text after a hash (#) is considered a comment and will be ignored.
+# The format is:
+#       TAG = value [value, ...]
+# For lists items can also be appended using:
+#       TAG += value [value, ...]
+# Values that contain spaces should be placed between quotes (" ").
+
+#---------------------------------------------------------------------------
+# Project related configuration options
+#---------------------------------------------------------------------------
+
+# This tag specifies the encoding used for all characters in the config file
+# that follow. The default is UTF-8 which is also the encoding used for all
+# text before the first occurrence of this tag. Doxygen uses libiconv (or the
+# iconv built into libc) for the transcoding. See
+# http://www.gnu.org/software/libiconv for the list of possible encodings.
+
+DOXYFILE_ENCODING      = UTF-8
+
+# The PROJECT_NAME tag is a single word (or sequence of words) that should
+# identify the project. Note that if you do not use Doxywizard you need
+# to put quotes around the project name if it contains spaces.
+
+PROJECT_NAME           = "libnsgif"
+
+# The PROJECT_NUMBER tag can be used to enter a project or revision number.
+# This could be handy for archiving the generated documentation or
+5A# if some version control system is used.
+
+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 quick idea about the purpose of the project. Keep the description short.
+
+PROJECT_BRIEF          =
+
+# With the PROJECT_LOGO tag one can specify an logo or icon that is
+# included in the documentation. The maximum height of the logo should not
+# exceed 55 pixels and the maximum width should not exceed 200 pixels.
+# Doxygen will copy the logo to the output directory.
+
+PROJECT_LOGO           =
+
+# The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute)
+# base path where the generated documentation will be put.
+# If a relative path is entered, it will be relative to the location
+# where doxygen was started. If left blank the current directory will be used.
+
+OUTPUT_DIRECTORY       = docs/
+
+# 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 option can be useful when feeding doxygen a huge amount of
+# source files, where putting all generated files in the same directory would
+# otherwise cause performance problems for the file system.
+
+CREATE_SUBDIRS         = 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.
+# The default language is English, other supported languages are:
+# Afrikaans, Arabic, Brazilian, Catalan, Chinese, Chinese-Traditional,
+# Croatian, Czech, Danish, Dutch, Esperanto, Farsi, Finnish, French, German,
+# Greek, Hungarian, Italian, Japanese, Japanese-en (Japanese with English
+# messages), Korean, Korean-en, Lithuanian, Norwegian, Macedonian, Persian,
+# Polish, Portuguese, Romanian, Russian, Serbian, Serbian-Cyrillic, Slovak,
+# Slovene, Spanish, Swedish, Ukrainian, and Vietnamese.
+
+OUTPUT_LANGUAGE        = English
+
+# If the BRIEF_MEMBER_DESC tag is set to YES (the default) 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.
+
+BRIEF_MEMBER_DESC      = YES
+
+# If the REPEAT_BRIEF tag is set to YES (the default) Doxygen will prepend
+# the brief description of a member or function before the detailed description.
+# Note: if both HIDE_UNDOC_MEMBERS and BRIEF_MEMBER_DESC are set to NO, the
+# brief descriptions will be completely suppressed.
+
+REPEAT_BRIEF           = YES
+
+# This tag implements a quasi-intelligent brief description abbreviator
+# that is used to form the text in various listings. Each string
+# in this list, if found as the leading text of the brief description, will be
+# stripped from the text and the result after processing the whole list, is
+# used as the annotated text. Otherwise, the brief description is used as-is.
+# If left blank, the following values are used ("$name" is automatically
+# replaced with the name of the entity): "The $name class" "The $name widget"
+# "The $name file" "is" "provides" "specifies" "contains"
+# "represents" "a" "an" "the"
+
+ABBREVIATE_BRIEF       =
+
+# If the ALWAYS_DETAILED_SEC and REPEAT_BRIEF tags are both set to YES then
+# Doxygen will generate a detailed section even if there is only a brief
+# description.
+
+ALWAYS_DETAILED_SEC    = NO
+
+# If the INLINE_INHERITED_MEMB tag is set to YES, doxygen will show all
+# inherited members of a class in the documentation of that class as if those
+# members were ordinary class members. Constructors, destructors and assignment
+# operators of the base classes will not be shown.
+
+INLINE_INHERITED_MEMB  = NO
+
+# If the FULL_PATH_NAMES tag is set to YES then Doxygen will prepend the full
+# path before files name in the file list and in the header files. If set
+# to NO the shortest path that makes the file name unique will be used.
+
+FULL_PATH_NAMES        = YES
+
+# If the FULL_PATH_NAMES tag is set to YES then the STRIP_FROM_PATH tag
+# can be used to strip a user-defined part of the path. Stripping is
+# only done if one of the specified strings matches the left-hand part of
+# the path. The tag can be used to show relative paths in the file list.
+# If left blank the directory from which doxygen is run is used as the
+# path to strip.
+
+STRIP_FROM_PATH        =
+
+# 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 header file to include in order to use a class.
+# If left blank only the name of the header file containing the class
+# definition is used. Otherwise one should specify the include paths that
+# are normally passed to the compiler using the -I flag.
+
+STRIP_FROM_INC_PATH    =
+
+# If the SHORT_NAMES tag is set to YES, doxygen will generate much shorter
+# (but less readable) file names. This can be useful if your file system
+# doesn't support long names like on DOS, Mac, or CD-ROM.
+
+SHORT_NAMES            = NO
+
+# If the JAVADOC_AUTOBRIEF tag is set to YES then Doxygen
+# will interpret the first line (until the first dot) of a JavaDoc-style
+# comment as the brief description. If set to NO, the JavaDoc
+# comments will behave just like regular Qt-style comments
+# (thus requiring an explicit @brief command for a brief description.)
+
+JAVADOC_AUTOBRIEF      = NO
+
+# If the QT_AUTOBRIEF tag is set to YES then Doxygen will
+# interpret the first line (until the first dot) of a Qt-style
+# comment as the brief description. If set to NO, the comments
+# will behave just like regular Qt-style comments (thus requiring
+# an explicit \brief command for a brief description.)
+
+QT_AUTOBRIEF           = NO
+
+# The MULTILINE_CPP_IS_BRIEF tag can be set to YES to make Doxygen
+# treat a multi-line C++ special comment block (i.e. a block of //! or ///
+# comments) as a brief description. This used to be the default behaviour.
+# The new default is to treat a multi-line C++ comment block as a detailed
+# description. Set this tag to YES if you prefer the old behaviour instead.
+
+MULTILINE_CPP_IS_BRIEF = NO
+
+# If the INHERIT_DOCS tag is set to YES (the default) then an undocumented
+# member inherits the documentation from any documented member that it
+# re-implements.
+
+INHERIT_DOCS           = YES
+
+# If the SEPARATE_MEMBER_PAGES tag is set to YES, then doxygen will produce
+# a new page for each member. If set to NO, the documentation of a member will
+# be part of the file/class/namespace that contains it.
+
+SEPARATE_MEMBER_PAGES  = NO
+
+# The TAB_SIZE tag can be used to set the number of spaces in a tab.
+# Doxygen uses this value to replace tabs by spaces in code fragments.
+
+TAB_SIZE               = 8
+
+# This tag can be used to specify a number of aliases that acts
+# as commands in the documentation. An alias has the form "name=value".
+# For example adding "sideeffect=\par Side Effects:\n" 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.
+
+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 members will be omitted, etc.
+
+OPTIMIZE_OUTPUT_FOR_C  = YES
+
+# Set the OPTIMIZE_OUTPUT_JAVA tag to YES if your project consists of Java
+# sources only. Doxygen will then generate output that is more tailored for
+# Java. For instance, namespaces will be presented as packages, qualified
+# scopes will look different, etc.
+
+OPTIMIZE_OUTPUT_JAVA   = NO
+
+# Set the OPTIMIZE_FOR_FORTRAN tag to YES if your project consists of Fortran
+# sources only. Doxygen will then generate output that is more tailored for
+# Fortran.
+
+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.
+
+OPTIMIZE_OUTPUT_VHDL   = 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++, D, PHP, Objective-C, Python, Fortran, VHDL, C, C++. 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 that for custom extensions
+# you also need to set FILE_PATTERNS otherwise the files are not read by doxygen.
+
+EXTENSION_MAPPING      =
+
+# If MARKDOWN_SUPPORT is enabled (the default) then doxygen pre-processes all
+# comments according to the Markdown format, which allows for more readable
+# documentation. See http://daringfireball.net/projects/markdown/ for details.
+# The output of markdown processing is further processed by doxygen, so you
+# can mix doxygen, HTML, and XML commands with Markdown formatting.
+# Disable only in case of backward compatibilities issues.
+
+MARKDOWN_SUPPORT       = YES
+
+# If you use STL classes (i.e. std::string, std::vector, etc.) but do not want
+# to include (a tag file for) the STL sources as input, then you should
+# set this tag to YES in order to let doxygen match functions declarations and
+# definitions whose arguments contain STL classes (e.g. func(std::string); v.s.
+# func(std::string) {}). This also makes the inheritance and collaboration
+# diagrams that involve STL classes more complete and accurate.
+
+BUILTIN_STL_SUPPORT    = NO
+
+# If you use Microsoft's C++/CLI language, you should set this option to YES to
+# enable parsing support.
+
+CPP_CLI_SUPPORT        = NO
+
+# Set the SIP_SUPPORT tag to YES if your project consists of sip sources only.
+# Doxygen will parse them like normal C++ but will assume all classes use public
+# instead of private inheritance when no explicit protection keyword is present.
+
+SIP_SUPPORT            = NO
+
+# For Microsoft's IDL there are propget and propput attributes to indicate getter
+# and setter methods for a property. Setting this option to YES (the default)
+# will make doxygen replace the get and set methods by a property in the
+# documentation. This will only work if the methods are indeed getting or
+# setting a simple type. If this is not the case, or you want to show the
+# methods anyway, you should set this option to NO.
+
+IDL_PROPERTY_SUPPORT   = YES
+
+# If member grouping is used in the documentation and the DISTRIBUTE_GROUP_DOC
+# tag is set to YES, then doxygen will reuse the documentation of the first
+# member in the group (if any) for the other members of the group. By default
+# all members of a group must be documented explicitly.
+
+DISTRIBUTE_GROUP_DOC   = NO
+
+# Set the SUBGROUPING tag to YES (the default) to allow class member groups of
+# the same type (for instance a group of public functions) to be put as a
+# subgroup of that type (e.g. under the Public Functions section). Set it to
+# NO to prevent subgrouping. Alternatively, this can be done per class using
+# the \nosubgrouping command.
+
+SUBGROUPING            = YES
+
+# When the INLINE_GROUPED_CLASSES tag is set to YES, classes, structs and
+# unions are shown inside the group in which they are included (e.g. using
+# @ingroup) instead of on a separate page (for HTML and Man pages) or
+# section (for LaTeX and RTF).
+
+INLINE_GROUPED_CLASSES = NO
+
+# When the INLINE_SIMPLE_STRUCTS tag is set to YES, structs, classes, and
+# unions with only public data fields will be shown inline in the documentation
+# of the scope in which they are defined (i.e. file, namespace, or group
+# documentation), provided this scope is documented. If set to NO (the default),
+# structs, classes, and unions are shown on a separate page (for HTML and Man
+# pages) or section (for LaTeX and RTF).
+
+INLINE_SIMPLE_STRUCTS  = NO
+
+# When TYPEDEF_HIDES_STRUCT is enabled, a typedef of a struct, union, or enum
+# is documented as struct, union, or enum with the name of the typedef. So
+# typedef struct TypeS {} TypeT, will appear in the documentation as a struct
+# with name TypeT. When disabled the typedef will appear as a member of a file,
+# namespace, or class. And the struct will be named TypeS. This can typically
+# be useful for C code in case the coding convention dictates that all compound
+# types are typedef'ed and only the typedef is referenced, never the tag name.
+
+TYPEDEF_HIDES_STRUCT   = NO
+
+# The SYMBOL_CACHE_SIZE determines the size of the internal cache use to
+# determine which symbols to keep in memory and which to flush to disk.
+# When the cache is full, less often used symbols will be written to disk.
+# For small to medium size projects (<1000 input files) the default value is
+# probably good enough. For larger projects a too small cache size can cause
+# doxygen to be busy swapping symbols to and from disk most of the time
+# causing a significant performance penalty.
+# If the system has enough physical memory increasing the cache will improve the
+# performance by keeping more symbols in memory. Note that the value works on
+# a logarithmic scale so increasing the size by one will roughly double the
+# memory usage. The cache size is given by this formula:
+# 2^(16+SYMBOL_CACHE_SIZE). The valid range is 0..9, the default is 0,
+# corresponding to a cache size of 2^16 = 65536 symbols.
+
+SYMBOL_CACHE_SIZE      = 0
+
+# Similar to the SYMBOL_CACHE_SIZE the size of the symbol lookup cache can be
+# set using LOOKUP_CACHE_SIZE. This cache is used to resolve symbols given
+# their name and scope. Since this can be an expensive process and often the
+# same symbol appear multiple times in the code, doxygen keeps a cache of
+# pre-resolved symbols. If the cache is too small doxygen will become slower.
+# If the cache is too large, memory is wasted. The cache size is given by this
+# formula: 2^(16+LOOKUP_CACHE_SIZE). The valid range is 0..9, the default is 0,
+# corresponding to a cache size of 2^16 = 65536 symbols.
+
+LOOKUP_CACHE_SIZE      = 0
+
+#---------------------------------------------------------------------------
+# Build related configuration options
+#---------------------------------------------------------------------------
+
+# If the EXTRACT_ALL tag is set to YES doxygen will assume all entities in
+# documentation are documented, even if no documentation was available.
+# Private class members and static file members will be hidden unless
+# the EXTRACT_PRIVATE and EXTRACT_STATIC tags are set to YES
+
+EXTRACT_ALL            = YES
+
+# If the EXTRACT_PRIVATE tag is set to YES all private members of a class
+# will be included in the documentation.
+
+EXTRACT_PRIVATE        = NO
+
+# If the EXTRACT_PACKAGE tag is set to YES all members with package or internal scope will be included in the documentation.
+
+EXTRACT_PACKAGE        = NO
+
+# If the EXTRACT_STATIC tag is set to YES all static members of a file
+# will be included in the documentation.
+
+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 only classes defined in header files are included.
+
+EXTRACT_LOCAL_CLASSES  = YES
+
+# This flag is only useful for Objective-C code. When set to YES local
+# methods, which are defined in the implementation section but not in
+# the interface are included in the documentation.
+# If set to NO (the default) only methods in the interface are included.
+
+EXTRACT_LOCAL_METHODS  = NO
+
+# If this flag is set to YES, the members of anonymous namespaces will be
+# extracted and appear in the documentation as a namespace called
+# 'anonymous_namespace{file}', where file will be replaced with the base
+# name of the file that contains the anonymous namespace. By default
+# anonymous namespaces are hidden.
+
+EXTRACT_ANON_NSPACES   = NO
+
+# If the HIDE_UNDOC_MEMBERS tag is set to YES, Doxygen will hide all
+# undocumented members of documented classes, files or namespaces.
+# If set to NO (the default) these members will be included in the
+# various overviews, but no documentation section is generated.
+# This option has no effect if EXTRACT_ALL is enabled.
+
+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 (the default) these classes will be included in the various
+# overviews. This option has no effect if EXTRACT_ALL is enabled.
+
+HIDE_UNDOC_CLASSES     = NO
+
+# If the HIDE_FRIEND_COMPOUNDS tag is set to YES, Doxygen will hide all
+# friend (class|struct|union) declarations.
+# If set to NO (the default) these declarations will be included in the
+# documentation.
+
+HIDE_FRIEND_COMPOUNDS  = NO
+
+# If the HIDE_IN_BODY_DOCS tag is set to YES, Doxygen will hide any
+# documentation blocks found inside the body of a function.
+# If set to NO (the default) these blocks will be appended to the
+# function's detailed documentation block.
+
+HIDE_IN_BODY_DOCS      = NO
+
+# The INTERNAL_DOCS tag determines if documentation
+# that is typed after a \internal command is included. If the tag is set
+# to NO (the default) then the documentation will be excluded.
+# Set it to YES to include the internal documentation.
+
+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
+# and Mac users are advised to set this option to NO.
+
+CASE_SENSE_NAMES       = YES
+
+# If the HIDE_SCOPE_NAMES tag is set to NO (the default) then Doxygen
+# will show members with their full class and namespace scopes in the
+# documentation. If set to YES the scope will be hidden.
+
+HIDE_SCOPE_NAMES       = NO
+
+# If the SHOW_INCLUDE_FILES tag is set to YES (the default) then Doxygen
+# will put a list of the files that are included by a file in the documentation
+# of that file.
+
+SHOW_INCLUDE_FILES     = YES
+
+# If the FORCE_LOCAL_INCLUDES tag is set to YES then Doxygen
+# will list include files with double quotes in the documentation
+# rather than with sharp brackets.
+
+FORCE_LOCAL_INCLUDES   = NO
+
+# If the INLINE_INFO tag is set to YES (the default) then a tag [inline]
+# is inserted in the documentation for inline members.
+
+INLINE_INFO            = YES
+
+# If the SORT_MEMBER_DOCS tag is set to YES (the default) then doxygen
+# will sort the (detailed) documentation of file and class members
+# alphabetically by member name. If set to NO the members will appear in
+# declaration order.
+
+SORT_MEMBER_DOCS       = YES
+
+# If the SORT_BRIEF_DOCS tag is set to YES then doxygen will sort the
+# brief documentation of file, namespace and class members alphabetically
+# by member name. If set to NO (the default) the members will appear in
+# declaration order.
+
+SORT_BRIEF_DOCS        = NO
+
+# If the SORT_MEMBERS_CTORS_1ST tag is set to YES then doxygen
+# will sort the (brief and detailed) documentation of class members so that
+# constructors and destructors are listed first. If set to NO (the default)
+# the constructors will appear in the respective orders defined by
+# SORT_MEMBER_DOCS and SORT_BRIEF_DOCS.
+# This tag will be ignored for brief docs if SORT_BRIEF_DOCS is set to NO
+# and ignored for detailed docs if SORT_MEMBER_DOCS is set to NO.
+
+SORT_MEMBERS_CTORS_1ST = NO
+
+# If the SORT_GROUP_NAMES tag is set to YES then doxygen will sort the
+# hierarchy of group names into alphabetical order. If set to NO (the default)
+# the group names will appear in their defined order.
+
+SORT_GROUP_NAMES       = NO
+
+# If the SORT_BY_SCOPE_NAME tag is set to YES, the class list will be
+# sorted by fully-qualified names, including namespaces. If set to
+# NO (the default), the class list will be sorted only by class name,
+# not including the namespace part.
+# Note: This option is not very useful if HIDE_SCOPE_NAMES is set to YES.
+# Note: This option applies only to the class list, not to the
+# alphabetical list.
+
+SORT_BY_SCOPE_NAME     = NO
+
+# If the STRICT_PROTO_MATCHING option is enabled and doxygen fails to
+# do proper type resolution of all parameters of a function it will reject a
+# match between the prototype and the implementation of a member function even
+# if there is only one candidate or it is obvious which candidate to choose
+# by doing a simple string match. By disabling STRICT_PROTO_MATCHING doxygen
+# will still accept a match between prototype and implementation in such cases.
+
+STRICT_PROTO_MATCHING  = NO
+
+# The GENERATE_TODOLIST tag can be used to enable (YES) or
+# disable (NO) the todo list. This list is created by putting \todo
+# commands in the documentation.
+
+GENERATE_TODOLIST      = YES
+
+# The GENERATE_TESTLIST tag can be used to enable (YES) or
+# disable (NO) the test list. This list is created by putting \test
+# commands in the documentation.
+
+GENERATE_TESTLIST      = YES
+
+# The GENERATE_BUGLIST tag can be used to enable (YES) or
+# disable (NO) the bug list. This list is created by putting \bug
+# commands in the documentation.
+
+GENERATE_BUGLIST       = YES
+
+# The GENERATE_DEPRECATEDLIST tag can be used to enable (YES) or
+# disable (NO) the deprecated list. This list is created by putting
+# \deprecated commands in the documentation.
+
+GENERATE_DEPRECATEDLIST= YES
+
+# The ENABLED_SECTIONS tag can be used to enable conditional
+# documentation sections, marked by \if sectionname ... \endif.
+
+ENABLED_SECTIONS       =
+
+# The MAX_INITIALIZER_LINES tag determines the maximum number of lines
+# the initial value of a variable or macro consists of for it to appear in
+# the documentation. If the initializer consists of more lines than specified
+# here it will be hidden. Use a value of 0 to hide initializers completely.
+# The appearance of the initializer of individual variables and macros in the
+# documentation can be controlled using \showinitializer or \hideinitializer
+# command in the documentation regardless of this setting.
+
+MAX_INITIALIZER_LINES  = 30
+
+# Set the SHOW_USED_FILES tag to NO to disable the list of files generated
+# at the bottom of the documentation of classes and structs. If set to YES the
+# list will mention the files that were used to generate the documentation.
+
+SHOW_USED_FILES        = YES
+
+# Set the SHOW_FILES tag to NO to disable the generation of the Files page.
+# This will remove the Files entry from the Quick Index and from the
+# Folder Tree View (if specified). The default is YES.
+
+SHOW_FILES             = YES
+
+# Set the SHOW_NAMESPACES tag to NO to disable the generation of the
+# Namespaces page.
+# This will remove the Namespaces entry from the Quick Index
+# and from the Folder Tree View (if specified). The default is YES.
+
+SHOW_NAMESPACES        = YES
+
+# The FILE_VERSION_FILTER tag can be used to specify a program or script that
+# doxygen should invoke to get the current version for each file (typically from
+# the version control system). Doxygen will invoke the program by executing (via
+# popen()) the command <command> <input-file>, where <command> is the value of
+# the FILE_VERSION_FILTER tag, and <input-file> is the name of an input file
+# provided by doxygen. Whatever the program writes to standard output
+# is used as the file version. See the manual for examples.
+
+FILE_VERSION_FILTER    =
+
+# The LAYOUT_FILE tag can be used to specify a layout file which will be parsed
+# by doxygen. The layout file controls the global structure of the generated
+# 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.
+
+LAYOUT_FILE            =
+
+# The CITE_BIB_FILES tag can be used to specify one or more bib files
+# containing the references data. This must be a list of .bib files. The
+# .bib extension is automatically appended if omitted. Using this command
+# requires the bibtex tool to be installed. See also
+# http://en.wikipedia.org/wiki/BibTeX for more info. For LaTeX the style
+# of the bibliography can be controlled using LATEX_BIB_STYLE. To use this
+# feature you need bibtex and perl available in the search path.
+
+CITE_BIB_FILES         =
+
+#---------------------------------------------------------------------------
+# configuration options related to warning and progress messages
+#---------------------------------------------------------------------------
+
+# The QUIET tag can be used to turn on/off the messages that are generated
+# by doxygen. Possible values are YES and NO. If left blank NO is used.
+
+QUIET                  = NO
+
+# The WARNINGS tag can be used to turn on/off the warning messages that are
+# generated by doxygen. Possible values are YES and NO. If left blank
+# NO is used.
+
+WARNINGS               = YES
+
+# If WARN_IF_UNDOCUMENTED is set to YES, then doxygen will generate warnings
+# for undocumented members. If EXTRACT_ALL is set to YES then this flag will
+# automatically be disabled.
+
+WARN_IF_UNDOCUMENTED   = YES
+
+# If WARN_IF_DOC_ERROR 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.
+
+WARN_IF_DOC_ERROR      = YES
+
+# The 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 (the default) doxygen will only warn about
+# wrong or incomplete parameter documentation, but not about the absence of
+# documentation.
+
+WARN_NO_PARAMDOC       = NO
+
+# The WARN_FORMAT tag determines the format of the warning messages that
+# doxygen can produce. The string should contain the $file, $line, and $text
+# tags, which will be replaced by the file and line number from which the
+# warning originated and the warning text. Optionally the format may contain
+# $version, which will be replaced by the version of the file (if it could
+# be obtained via FILE_VERSION_FILTER)
+
+WARN_FORMAT            = "$file:$line: $text"
+
+# 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 stderr.
+
+WARN_LOGFILE           =
+
+#---------------------------------------------------------------------------
+# configuration options related to the input files
+#---------------------------------------------------------------------------
+
+# The INPUT tag can be used to specify the files and/or directories that contain
+# documented source files. You may enter file names like "myfile.cpp" or
+# directories like "/usr/src/myproject". Separate the files or directories
+# with spaces.
+
+INPUT                  =
+
+# This tag can be used to specify the character encoding of the source files
+# that doxygen parses. Internally doxygen uses the UTF-8 encoding, which is
+# also the default input encoding. Doxygen uses libiconv (or the iconv built
+# into libc) for the transcoding. See http://www.gnu.org/software/libiconv for
+# the list of possible encodings.
+
+INPUT_ENCODING         = UTF-8
+
+# If the value of the INPUT tag contains directories, you can use the
+# FILE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp
+# and *.h) to filter out the source-files in the directories. If left
+# blank the following patterns are tested:
+# *.c *.cc *.cxx *.cpp *.c++ *.d *.java *.ii *.ixx *.ipp *.i++ *.inl *.h *.hh
+# *.hxx *.hpp *.h++ *.idl *.odl *.cs *.php *.php3 *.inc *.m *.mm *.dox *.py
+# *.f90 *.f *.for *.vhd *.vhdl
+
+FILE_PATTERNS          =
+
+# The RECURSIVE tag can be used to turn specify whether or not subdirectories
+# should be searched for input files as well. Possible values are YES and NO.
+# If left blank NO is used.
+
+RECURSIVE              = YES
+
+# The EXCLUDE tag can be used to specify files and/or directories that should be
+# excluded from the INPUT source files. This way you can easily exclude a
+# subdirectory from a directory tree whose root is specified with the INPUT tag.
+# Note that relative paths are relative to the directory from which doxygen is
+# run.
+
+EXCLUDE                =
+
+# The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
+# directories that are symbolic links (a Unix file system feature) are excluded
+# from the input.
+
+EXCLUDE_SYMLINKS       = NO
+
+# If the value of the INPUT tag contains directories, you can use the
+# EXCLUDE_PATTERNS tag to specify one or more wildcard patterns to exclude
+# certain files from those directories. Note that the wildcards are matched
+# against the file with absolute path, so to exclude all test directories
+# for example use the pattern */test/*
+
+EXCLUDE_PATTERNS       =
+
+# The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
+# (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
+
+EXCLUDE_SYMBOLS        =
+
+# The EXAMPLE_PATH tag can be used to specify one or more files or
+# directories that contain example code fragments that are included (see
+# the \include command).
+
+EXAMPLE_PATH           =
+
+# If the value of the EXAMPLE_PATH tag contains directories, you can use the
+# EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp
+# and *.h) to filter out the source-files in the directories. If left
+# blank all files are included.
+
+EXAMPLE_PATTERNS       =
+
+# If the EXAMPLE_RECURSIVE tag is set to YES then subdirectories will be
+# searched for input files to be used with the \include or \dontinclude
+# commands irrespective of the value of the RECURSIVE tag.
+# Possible values are YES and NO. If left blank NO is used.
+
+EXAMPLE_RECURSIVE      = NO
+
+# The IMAGE_PATH tag can be used to specify one or more files or
+# directories that contain image that are included in the documentation (see
+# the \image command).
+
+IMAGE_PATH             =
+
+# The INPUT_FILTER tag can be used to specify a program that doxygen should
+# invoke to filter for each input file. Doxygen will invoke the filter program
+# by executing (via popen()) the command <filter> <input-file>, where <filter>
+# is the value of the INPUT_FILTER tag, and <input-file> is the name of an
+# input file. Doxygen will then use the output that the filter program writes
+# to standard output.
+# If FILTER_PATTERNS is specified, this tag will be
+# ignored.
+
+INPUT_FILTER           =
+
+# The FILTER_PATTERNS tag can be used to specify filters on a per file pattern
+# basis.
+# Doxygen will compare the file name with each pattern and apply the
+# filter if there is a match.
+# The filters are a list of the form:
+# pattern=filter (like *.cpp=my_cpp_filter). See INPUT_FILTER for further
+# info on how filters are used. If FILTER_PATTERNS is empty or if
+# non of the patterns match the file name, INPUT_FILTER is applied.
+
+FILTER_PATTERNS        =
+
+# If the FILTER_SOURCE_FILES tag is set to YES, the input filter (if set using
+# INPUT_FILTER) will be used to filter the input files when producing source
+# files to browse (i.e. when SOURCE_BROWSER is set to YES).
+
+FILTER_SOURCE_FILES    = NO
+
+# The FILTER_SOURCE_PATTERNS tag can be used to specify source filters per file
+# pattern. A pattern will override the setting for FILTER_PATTERN (if any)
+# and it is also possible to disable source filtering for a specific pattern
+# using *.ext= (so without naming a filter). This option only has effect when
+# FILTER_SOURCE_FILES is enabled.
+
+FILTER_SOURCE_PATTERNS =
+
+#---------------------------------------------------------------------------
+# configuration options related to source browsing
+#---------------------------------------------------------------------------
+
+# If the SOURCE_BROWSER tag is set to YES then a list of source files will
+# be generated. Documented entities will be cross-referenced with these sources.
+# Note: To get rid of all source code in the generated output, make sure also
+# VERBATIM_HEADERS is set to NO.
+
+SOURCE_BROWSER         = NO
+
+# Setting the INLINE_SOURCES tag to YES will include the body
+# of functions and classes directly in the documentation.
+
+INLINE_SOURCES         = NO
+
+# Setting the STRIP_CODE_COMMENTS tag to YES (the default) will instruct
+# doxygen to hide any special comment blocks from generated source code
+# fragments. Normal C, C++ and Fortran comments will always remain visible.
+
+STRIP_CODE_COMMENTS    = YES
+
+# If the REFERENCED_BY_RELATION tag is set to YES
+# then for each documented function all documented
+# functions referencing it will be listed.
+
+REFERENCED_BY_RELATION = NO
+
+# If the REFERENCES_RELATION tag is set to YES
+# then for each documented function all documented entities
+# called/used by that function will be listed.
+
+REFERENCES_RELATION    = NO
+
+# If the REFERENCES_LINK_SOURCE tag is set to YES (the default)
+# and SOURCE_BROWSER tag is set to YES, then the hyperlinks from
+# functions in REFERENCES_RELATION and REFERENCED_BY_RELATION lists will
+# link to the source code.
+# Otherwise they will link to the documentation.
+
+REFERENCES_LINK_SOURCE = YES
+
+# If the USE_HTAGS tag is set to YES then the references to source code
+# will point to the HTML generated by the htags(1) tool instead of doxygen
+# built-in source browser. The htags tool is part of GNU's global source
+# tagging system (see http://www.gnu.org/software/global/global.html). You
+# will need version 4.8.6 or higher.
+
+USE_HTAGS              = NO
+
+# If the VERBATIM_HEADERS tag is set to YES (the default) then Doxygen
+# will generate a verbatim copy of the header file for each class for
+# which an include is specified. Set to NO to disable this.
+
+VERBATIM_HEADERS       = YES
+
+#---------------------------------------------------------------------------
+# configuration options related to the alphabetical class index
+#---------------------------------------------------------------------------
+
+# If the ALPHABETICAL_INDEX tag is set to YES, an alphabetical index
+# of all compounds will be generated. Enable this if the project
+# contains a lot of classes, structs, unions or interfaces.
+
+ALPHABETICAL_INDEX     = YES
+
+# If the alphabetical index is enabled (see ALPHABETICAL_INDEX) then
+# the COLS_IN_ALPHA_INDEX tag can be used to specify the number of columns
+# in which this list will be split (can be a number in the range [1..20])
+
+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 one or more prefixes that
+# should be ignored while generating the index headers.
+
+IGNORE_PREFIX          =
+
+#---------------------------------------------------------------------------
+# configuration options related to the HTML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_HTML tag is set to YES (the default) Doxygen will
+# generate HTML output.
+
+GENERATE_HTML          = YES
+
+# The HTML_OUTPUT tag is used to specify where the HTML docs will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be
+# put in front of it. If left blank `html' will be used as the default path.
+
+HTML_OUTPUT            = html
+
+# The HTML_FILE_EXTENSION tag can be used to specify the file extension for
+# each generated HTML page (for example: .htm,.php,.asp). If it is left blank
+# doxygen will generate files with .html extension.
+
+HTML_FILE_EXTENSION    = .html
+
+# The HTML_HEADER tag can be used to specify a personal HTML header for
+# each generated HTML page. If it is left blank doxygen will generate a
+# standard header. Note that when using a custom header you are responsible
+#  for the proper inclusion of any scripts and style sheets that doxygen
+# needs, which is dependent on the configuration options used.
+# It is advised to generate a default header using "doxygen -w html
+# header.html footer.html stylesheet.css YourConfigFile" and then modify
+# that header. Note that the header is subject to change so you typically
+# have to redo this when upgrading to a newer version of doxygen or when
+# changing the value of configuration settings such as GENERATE_TREEVIEW!
+
+HTML_HEADER            =
+
+# The HTML_FOOTER tag can be used to specify a personal HTML footer for
+# each generated HTML page. If it is left blank doxygen will generate a
+# standard footer.
+
+HTML_FOOTER            =
+
+# The HTML_STYLESHEET tag can be used to specify a user-defined cascading
+# style sheet that is used by each HTML page. It can be used to
+# fine-tune the look of the HTML output. If the tag is left blank doxygen
+# will generate a default style sheet. Note that doxygen will try to copy
+# the style sheet file to the HTML output directory, so don't put your own
+# style sheet in the HTML output directory as well, or it will be erased!
+
+HTML_STYLESHEET        =
+
+# The HTML_EXTRA_FILES tag can be used to specify one or more extra images or
+# other source files which should be copied to the HTML output directory. Note
+# that these files will be copied to the base HTML output directory. Use the
+# $relpath$ marker in the HTML_HEADER and/or HTML_FOOTER files to load these
+# files. In the HTML_STYLESHEET file, use the file name only. Also note that
+# the files will be copied as-is; there are no commands or markers available.
+
+HTML_EXTRA_FILES       =
+
+# 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 http://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.
+# The allowed range is 0 to 359.
+
+HTML_COLORSTYLE_HUE    = 220
+
+# 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 value of 255 will produce the most vivid colors.
+
+HTML_COLORSTYLE_SAT    = 100
+
+# The HTML_COLORSTYLE_GAMMA tag controls the gamma correction applied to
+# the luminance component of the colors in the HTML output. Values below
+# 100 gradually make the output lighter, whereas values above 100 make
+# the output darker. The value divided by 100 is the actual gamma applied,
+# so 80 represents a gamma of 0.8, The value 220 represents a gamma of 2.2,
+# and 100 does not change the gamma.
+
+HTML_COLORSTYLE_GAMMA  = 80
+
+# 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 to NO can help when comparing the output of multiple runs.
+
+HTML_TIMESTAMP         = YES
+
+# 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
+# page has loaded.
+
+HTML_DYNAMIC_SECTIONS  = NO
+
+# With HTML_INDEX_NUM_ENTRIES one can control the preferred number of
+# entries shown in the various tree structured indices initially; the user
+# can expand and collapse entries dynamically later on. Doxygen will expand
+# the tree to such a level that at most the specified number of entries are
+# visible (unless a fully collapsed tree already exceeds this amount).
+# So setting the number of entries 1 will produce a full collapsed tree by
+# default. 0 is a special value representing an infinite number of entries
+# and will result in a full expanded tree by default.
+
+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, 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 http://developer.apple.com/tools/creatingdocsetswithdoxygen.html
+# for more information.
+
+GENERATE_DOCSET        = NO
+
+# When GENERATE_DOCSET tag is set to YES, this tag determines the name of the
+# 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.
+
+DOCSET_FEEDNAME        = "Doxygen generated docs"
+
+# When GENERATE_DOCSET tag is set to YES, 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.
+
+DOCSET_BUNDLE_ID       = org.doxygen.Project
+
+# When GENERATE_PUBLISHER_ID tag specifies a string that should uniquely identify
+# the documentation publisher. This should be a reverse domain-name style
+# string, e.g. com.mycompany.MyDocSet.documentation.
+
+DOCSET_PUBLISHER_ID    = org.doxygen.Publisher
+
+# The GENERATE_PUBLISHER_NAME tag identifies the documentation publisher.
+
+DOCSET_PUBLISHER_NAME  = Publisher
+
+# If the GENERATE_HTMLHELP tag is set to YES, additional index files
+# will be generated that can be used as input for tools like the
+# Microsoft HTML help workshop to generate a compiled HTML help file (.chm)
+# of the generated HTML documentation.
+
+GENERATE_HTMLHELP      = NO
+
+# If the GENERATE_HTMLHELP tag is set to YES, the CHM_FILE tag can
+# be used to specify the file name of the resulting .chm file. You
+# can add a path in front of the file if the result should not be
+# written to the html output directory.
+
+CHM_FILE               =
+
+# If the GENERATE_HTMLHELP tag is set to YES, the HHC_LOCATION tag can
+# be used to specify the location (absolute path including file name) of
+# the HTML help compiler (hhc.exe). If non-empty doxygen will try to run
+# the HTML help compiler on the generated index.hhp.
+
+HHC_LOCATION           =
+
+# If the GENERATE_HTMLHELP tag is set to YES, 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).
+
+GENERATE_CHI           = NO
+
+# If the GENERATE_HTMLHELP tag is set to YES, the CHM_INDEX_ENCODING
+# is used to encode HtmlHelp index (hhk), content (hhc) and project file
+# content.
+
+CHM_INDEX_ENCODING     =
+
+# If the GENERATE_HTMLHELP tag is set to YES, the BINARY_TOC flag
+# controls whether a binary table of contents is generated (YES) or a
+# normal table of contents (NO) in the .chm file.
+
+BINARY_TOC             = NO
+
+# The TOC_EXPAND flag can be set to YES to add extra items for group members
+# to the contents of the HTML help documentation and to the tree view.
+
+TOC_EXPAND             = NO
+
+# If the GENERATE_QHP tag is set to YES and both QHP_NAMESPACE and
+# QHP_VIRTUAL_FOLDER are set, an additional index file will be generated
+# that can be used as input for Qt's qhelpgenerator to generate a
+# Qt Compressed Help (.qch) of the generated HTML documentation.
+
+GENERATE_QHP           = NO
+
+# If the QHG_LOCATION tag is specified, the QCH_FILE tag can
+# be used to specify the file name of the resulting .qch file.
+# The path specified is relative to the HTML output folder.
+
+QCH_FILE               =
+
+# The QHP_NAMESPACE tag specifies the namespace to use when generating
+# Qt Help Project output. For more information please see
+# http://doc.trolltech.com/qthelpproject.html#namespace
+
+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
+# http://doc.trolltech.com/qthelpproject.html#virtual-folders
+
+QHP_VIRTUAL_FOLDER     = doc
+
+# If QHP_CUST_FILTER_NAME is set, it specifies the name of a custom filter to
+# add. For more information please see
+# http://doc.trolltech.com/qthelpproject.html#custom-filters
+
+QHP_CUST_FILTER_NAME   =
+
+# The QHP_CUST_FILT_ATTRS tag specifies the list of the attributes of the
+# custom filter to add. For more information please see
+# <a href="http://doc.trolltech.com/qthelpproject.html#custom-filters">
+# Qt Help Project / Custom Filters</a>.
+
+QHP_CUST_FILTER_ATTRS  =
+
+# The QHP_SECT_FILTER_ATTRS tag specifies the list of the attributes this
+# project's
+# filter section matches.
+# <a href="http://doc.trolltech.com/qthelpproject.html#filter-attributes">
+# Qt Help Project / Filter Attributes</a>.
+
+QHP_SECT_FILTER_ATTRS  =
+
+# If the GENERATE_QHP tag is set to YES, 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.
+
+QHG_LOCATION           =
+
+# If the GENERATE_ECLIPSEHELP tag is set to YES, additional index files
+#  will be generated, which together with the HTML files, form an Eclipse help
+# plugin. To install this plugin and make it available under the help contents
+# menu in Eclipse, the contents of the directory containing the HTML and XML
+# files needs to be copied into the plugins directory of eclipse. The name of
+# the directory within the plugins directory should be the same as
+# the ECLIPSE_DOC_ID value. After copying Eclipse needs to be restarted before
+# the help appears.
+
+GENERATE_ECLIPSEHELP   = NO
+
+# A unique identifier for the eclipse help plugin. When installing the plugin
+# the directory name containing the HTML and XML files should also have
+# this name.
+
+ECLIPSE_DOC_ID         = org.doxygen.Project
+
+# The DISABLE_INDEX tag can be used to turn on/off the condensed index (tabs)
+# at top of each HTML page. The value NO (the default) enables the index and
+# the value YES disables it. Since the tabs have the same information as the
+# navigation tree you can set this option to NO if you already set
+# GENERATE_TREEVIEW to YES.
+
+DISABLE_INDEX          = NO
+
+# The GENERATE_TREEVIEW tag is used to specify whether a tree-like index
+# structure should be generated to display hierarchical information.
+# If the tag value is set to YES, a side panel will be generated
+# containing a tree-like index structure (just like the one that
+# is generated for HTML Help). For this 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.
+# Since the tree basically has the same information as the tab index you
+# could consider to set DISABLE_INDEX to NO when enabling this option.
+
+GENERATE_TREEVIEW      = NO
+
+# The ENUM_VALUES_PER_LINE tag can be used to set the number of enum values
+# (range [0,1..20]) that doxygen will group on one line in the generated HTML
+# documentation. Note that a value of 0 will completely suppress the enum
+# values from appearing in the overview section.
+
+ENUM_VALUES_PER_LINE   = 4
+
+# If the treeview is enabled (see GENERATE_TREEVIEW) then this tag can be
+# used to set the initial width (in pixels) of the frame in which the tree
+# is shown.
+
+TREEVIEW_WIDTH         = 250
+
+# When the EXT_LINKS_IN_WINDOW option is set to YES doxygen will open
+# links to external symbols imported via tag files in a separate window.
+
+EXT_LINKS_IN_WINDOW    = NO
+
+# Use this tag to change the font size of Latex formulas included
+# as images in the HTML documentation. The default is 10. Note that
+# when you change the font size after a successful doxygen run you need
+# to manually remove any form_*.png images from the HTML output directory
+# to force them to be regenerated.
+
+FORMULA_FONTSIZE       = 10
+
+# Use the FORMULA_TRANPARENT 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 before the changes have effect.
+
+FORMULA_TRANSPARENT    = YES
+
+# Enable the USE_MATHJAX option to render LaTeX formulas using MathJax
+# (see http://www.mathjax.org) which uses client side Javascript for the
+# rendering instead of using prerendered bitmaps. Use this if you do not
+# have LaTeX installed or if you want to formulas look prettier in the HTML
+# output. When enabled you may also need to install MathJax separately and
+# configure the path to it using the MATHJAX_RELPATH option.
+
+USE_MATHJAX            = NO
+
+# When MathJax is enabled you need to specify the location relative to the
+# HTML output directory using the MATHJAX_RELPATH option. The destination
+# directory should contain the MathJax.js script. For instance, if the mathjax
+# directory is located at the same level as the HTML output directory, then
+# 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 http://www.mathjax.org before deployment.
+
+MATHJAX_RELPATH        = http://cdn.mathjax.org/mathjax/latest
+
+# The MATHJAX_EXTENSIONS tag can be used to specify one or MathJax extension
+# names that should be enabled during MathJax rendering.
+
+MATHJAX_EXTENSIONS     =
+
+# When the SEARCHENGINE tag is enabled doxygen will generate a search box
+# for the HTML output. The underlying search engine uses javascript
+# and DHTML and should work on any modern browser. Note that when using
+# HTML help (GENERATE_HTMLHELP), Qt help (GENERATE_QHP), or docsets
+# (GENERATE_DOCSET) there is already a search function so this one should
+# typically be disabled. For large projects the javascript based search engine
+# can be slow, then enabling SERVER_BASED_SEARCH may provide a better solution.
+
+SEARCHENGINE           = YES
+
+# When the SERVER_BASED_SEARCH tag is enabled the search engine will be
+# implemented using a PHP enabled web server instead of at the web client
+# using Javascript. Doxygen will generate the search PHP script and index
+# file to put on the web server. The advantage of the server
+# based approach is that it scales better to large projects and allows
+# full text search. The disadvantages are that it is more difficult to setup
+# and does not have live searching capabilities.
+
+SERVER_BASED_SEARCH    = NO
+
+#---------------------------------------------------------------------------
+# configuration options related to the LaTeX output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_LATEX tag is set to YES (the default) Doxygen will
+# generate Latex output.
+
+GENERATE_LATEX         = NO
+
+# The LATEX_OUTPUT tag is used to specify where the LaTeX docs will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be
+# put in front of it. If left blank `latex' will be used as the default path.
+
+LATEX_OUTPUT           = latex
+
+# The LATEX_CMD_NAME tag can be used to specify the LaTeX command name to be
+# invoked. If left blank `latex' will be used as the default command name.
+# Note that when enabling USE_PDFLATEX this option is only used for
+# generating bitmaps for formulas in the HTML output, but not in the
+# Makefile that is written to the output directory.
+
+LATEX_CMD_NAME         = latex
+
+# The MAKEINDEX_CMD_NAME tag can be used to specify the command name to
+# generate index for LaTeX. If left blank `makeindex' will be used as the
+# default command name.
+
+MAKEINDEX_CMD_NAME     = makeindex
+
+# If the COMPACT_LATEX tag is set to YES Doxygen generates more compact
+# LaTeX documents. This may be useful for small projects and may help to
+# save some trees in general.
+
+COMPACT_LATEX          = NO
+
+# The PAPER_TYPE tag can be used to set the paper type that is used
+# by the printer. Possible values are: a4, letter, legal and
+# executive. If left blank a4wide will be used.
+
+PAPER_TYPE             = a4
+
+# The EXTRA_PACKAGES tag can be to specify one or more names of LaTeX
+# packages that should be included in the LaTeX output.
+
+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. Notice: only use this tag if you know what you are doing!
+
+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. Notice: only use this tag if you know what you are doing!
+
+LATEX_FOOTER           =
+
+# If the PDF_HYPERLINKS tag is set to YES, the LaTeX that is generated
+# is prepared for conversion to pdf (using ps2pdf). The pdf file will
+# contain links (just like the HTML output) instead of page references
+# This makes the output suitable for online browsing using a pdf viewer.
+
+PDF_HYPERLINKS         = YES
+
+# If the USE_PDFLATEX tag is set to YES, pdflatex will be used instead of
+# plain latex in the generated Makefile. Set this option to YES to get a
+# higher quality PDF documentation.
+
+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.
+
+LATEX_BATCHMODE        = NO
+
+# If LATEX_HIDE_INDICES is set to YES then doxygen will not
+# include the index chapters (such as File Index, Compound Index, etc.)
+# in the output.
+
+LATEX_HIDE_INDICES     = NO
+
+# If LATEX_SOURCE_CODE 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.
+
+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. The default style is "plain". See
+# http://en.wikipedia.org/wiki/BibTeX for more info.
+
+LATEX_BIB_STYLE        = plain
+
+#---------------------------------------------------------------------------
+# configuration options related to the RTF output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_RTF tag is set to YES Doxygen will generate RTF output
+# The RTF output is optimized for Word 97 and may not look very pretty with
+# other RTF readers or editors.
+
+GENERATE_RTF           = NO
+
+# The RTF_OUTPUT tag is used to specify where the RTF docs will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be
+# put in front of it. If left blank `rtf' will be used as the default path.
+
+RTF_OUTPUT             = rtf
+
+# If the COMPACT_RTF tag is set to YES Doxygen generates more compact
+# RTF documents. This may be useful for small projects and may help to
+# save some trees in general.
+
+COMPACT_RTF            = NO
+
+# If the RTF_HYPERLINKS tag is set to YES, the RTF that is generated
+# will contain hyperlink fields. The RTF file will
+# contain links (just like the HTML output) instead of page references.
+# This makes the output suitable for online browsing using WORD or other
+# programs which support those fields.
+# Note: wordpad (write) and others do not support links.
+
+RTF_HYPERLINKS         = NO
+
+# Load style sheet definitions from file. Syntax is similar to doxygen's
+# config file, i.e. a series of assignments. You only have to provide
+# replacements, missing definitions are set to their default value.
+
+RTF_STYLESHEET_FILE    =
+
+# Set optional variables used in the generation of an rtf document.
+# Syntax is similar to doxygen's config file.
+
+RTF_EXTENSIONS_FILE    =
+
+#---------------------------------------------------------------------------
+# configuration options related to the man page output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_MAN tag is set to YES (the default) Doxygen will
+# generate man pages
+
+GENERATE_MAN           = NO
+
+# The MAN_OUTPUT tag is used to specify where the man pages will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be
+# put in front of it. If left blank `man' will be used as the default path.
+
+MAN_OUTPUT             = man
+
+# The MAN_EXTENSION tag determines the extension that is added to
+# the generated man pages (default is the subroutine's section .3)
+
+MAN_EXTENSION          = .3
+
+# If the MAN_LINKS tag is set to YES and Doxygen generates man output,
+# then it will generate one additional man file for each entity
+# documented in the real man page(s). These additional files
+# only source the real man page, but without them the man command
+# would be unable to find the correct page. The default is NO.
+
+MAN_LINKS              = NO
+
+#---------------------------------------------------------------------------
+# configuration options related to the XML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_XML tag is set to YES Doxygen will
+# generate an XML file that captures the structure of
+# the code including all documentation.
+
+GENERATE_XML           = NO
+
+# The XML_OUTPUT tag is used to specify where the XML pages will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be
+# put in front of it. If left blank `xml' will be used as the default path.
+
+XML_OUTPUT             = xml
+
+# The XML_SCHEMA tag can be used to specify an XML schema,
+# which can be used by a validating XML parser to check the
+# syntax of the XML files.
+
+XML_SCHEMA             =
+
+# The XML_DTD tag can be used to specify an XML DTD,
+# which can be used by a validating XML parser to check the
+# syntax of the XML files.
+
+XML_DTD                =
+
+# If the XML_PROGRAMLISTING tag is set to YES Doxygen will
+# dump the program listings (including syntax highlighting
+# and cross-referencing information) to the XML output. Note that
+# enabling this will significantly increase the size of the XML output.
+
+XML_PROGRAMLISTING     = YES
+
+#---------------------------------------------------------------------------
+# configuration options for the AutoGen Definitions output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_AUTOGEN_DEF tag is set to YES Doxygen will
+# generate an AutoGen Definitions (see autogen.sf.net) file
+# that captures the structure of the code including all
+# documentation. Note that this feature is still experimental
+# and incomplete at the moment.
+
+GENERATE_AUTOGEN_DEF   = NO
+
+#---------------------------------------------------------------------------
+# configuration options related to the Perl module output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_PERLMOD tag is set to YES Doxygen will
+# generate a Perl module file that captures the structure of
+# the code including all documentation. Note that this
+# feature is still experimental and incomplete at the
+# moment.
+
+GENERATE_PERLMOD       = NO
+
+# If the PERLMOD_LATEX tag is set to YES Doxygen will generate
+# the necessary Makefile rules, Perl scripts and LaTeX code to be able
+# to generate PDF and DVI output from the Perl module output.
+
+PERLMOD_LATEX          = NO
+
+# If the PERLMOD_PRETTY tag is set to YES the Perl module output will be
+# nicely formatted so it can be parsed by a human reader.
+# This is useful
+# if you want to understand what is going on.
+# On the other hand, if this
+# tag is set to NO the size of the Perl module output will be much smaller
+# and Perl will parse it just the same.
+
+PERLMOD_PRETTY         = YES
+
+# The names of the make variables in the generated doxyrules.make file
+# are prefixed with the string contained in PERLMOD_MAKEVAR_PREFIX.
+# This is useful so different doxyrules.make files included by the same
+# Makefile don't overwrite each other's variables.
+
+PERLMOD_MAKEVAR_PREFIX =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the preprocessor
+#---------------------------------------------------------------------------
+
+# If the ENABLE_PREPROCESSING tag is set to YES (the default) Doxygen will
+# evaluate all C-preprocessor directives found in the sources and include
+# files.
+
+ENABLE_PREPROCESSING   = YES
+
+# If the MACRO_EXPANSION tag is set to YES Doxygen will expand all macro
+# names in the source code. If set to NO (the default) only conditional
+# compilation will be performed. Macro expansion can be done in a controlled
+# way by setting EXPAND_ONLY_PREDEF to YES.
+
+MACRO_EXPANSION        = NO
+
+# If the EXPAND_ONLY_PREDEF and MACRO_EXPANSION tags are both set to YES
+# then the macro expansion is limited to the macros specified with the
+# PREDEFINED and EXPAND_AS_DEFINED tags.
+
+EXPAND_ONLY_PREDEF     = NO
+
+# If the SEARCH_INCLUDES tag is set to YES (the default) the includes files
+# pointed to by INCLUDE_PATH will be searched when a #include is found.
+
+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.
+
+INCLUDE_PATH           =
+
+# You can use the INCLUDE_FILE_PATTERNS tag to specify one or more wildcard
+# patterns (like *.h and *.hpp) to filter out the header-files in the
+# directories. If left blank, the patterns specified with FILE_PATTERNS will
+# be used.
+
+INCLUDE_FILE_PATTERNS  =
+
+# The PREDEFINED tag can be used to specify one or more macro names that
+# are defined before the preprocessor is started (similar to the -D option of
+# gcc). The argument of the tag is a list of macros of the form: name
+# or name=definition (no spaces). If the definition and the = are
+# omitted =1 is assumed. To prevent a macro definition from being
+# undefined via #undef or recursively expanded use the := operator
+# instead of the = operator.
+
+PREDEFINED             =
+
+# If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then
+# this tag can be used to specify a list of macro names that should be expanded.
+# The macro definition that is found in the sources will be used.
+# Use the PREDEFINED tag if you want to use a different macro definition that
+# overrules the definition found in the source code.
+
+EXPAND_AS_DEFINED      =
+
+# If the SKIP_FUNCTION_MACROS tag is set to YES (the default) then
+# doxygen's preprocessor will remove all references to function-like macros
+# that are alone on a line, have an all uppercase name, and do not end with a
+# semicolon, because these will confuse the parser if not removed.
+
+SKIP_FUNCTION_MACROS   = YES
+
+#---------------------------------------------------------------------------
+# Configuration::additions related to external references
+#---------------------------------------------------------------------------
+
+# The TAGFILES option can be used to specify one or more tagfiles. For each
+# tag file the location of the external documentation should be added. The
+# format of a tag file without this location is as follows:
+#
+# TAGFILES = file1 file2 ...
+# Adding location for the tag files is done as follows:
+#
+# TAGFILES = file1=loc1 "file2 = loc2" ...
+# where "loc1" and "loc2" can be relative or absolute paths
+# or URLs. Note that each tag file must have a unique name (where the name does
+# NOT include the path). If a tag file is not located in the directory in which
+# doxygen is run, you must also specify the path to the tagfile here.
+
+TAGFILES               =
+
+# When a file name is specified after GENERATE_TAGFILE, doxygen will create
+# a tag file that is based on the input files it reads.
+
+GENERATE_TAGFILE       =
+
+# If the ALLEXTERNALS tag is set to YES all external classes will be listed
+# in the class index. If set to NO only the inherited external classes
+# will be listed.
+
+ALLEXTERNALS           = NO
+
+# If the EXTERNAL_GROUPS tag is set to YES all external groups will be listed
+# in the modules index. If set to NO, only the current project's groups will
+# be listed.
+
+EXTERNAL_GROUPS        = YES
+
+# The PERL_PATH should be the absolute path and name of the perl script
+# interpreter (i.e. the result of `which perl').
+
+PERL_PATH              = /usr/bin/perl
+
+#---------------------------------------------------------------------------
+# Configuration options related to the dot tool
+#---------------------------------------------------------------------------
+
+# If the CLASS_DIAGRAMS tag is set to YES (the default) Doxygen will
+# generate a inheritance diagram (in HTML, RTF 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.
+
+CLASS_DIAGRAMS         = YES
+
+# You can define message sequence charts within doxygen comments using the \msc
+# command. Doxygen will then run the mscgen tool (see
+# http://www.mcternan.me.uk/mscgen/) to produce the chart and insert it in the
+# documentation. The MSCGEN_PATH tag allows you to specify the directory where
+# the mscgen tool resides. If left empty the tool is assumed to be found in the
+# default search path.
+
+MSCGEN_PATH            =
+
+# If set to YES, the inheritance and collaboration graphs will hide
+# inheritance and usage relations if the target is undocumented
+# or is not a class.
+
+HIDE_UNDOC_RELATIONS   = YES
+
+# If you set the HAVE_DOT tag to YES then doxygen will assume the dot tool is
+# available from the path. This tool is part of Graphviz, 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)
+
+HAVE_DOT               = NO
+
+# The DOT_NUM_THREADS specifies the number of dot invocations doxygen is
+# allowed to run in parallel. When set to 0 (the default) doxygen will
+# base this on the number of processors available in the system. You can set it
+# explicitly to a value larger than 0 to get control over the balance
+# between CPU load and processing speed.
+
+DOT_NUM_THREADS        = 0
+
+# By default doxygen will use the Helvetica font for all dot files that
+# doxygen generates. When you want a differently looking font 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.
+
+DOT_FONTNAME           = Helvetica
+
+# The DOT_FONTSIZE tag can be used to set the size of the font of dot graphs.
+# The default size is 10pt.
+
+DOT_FONTSIZE           = 10
+
+# By default doxygen will tell dot to use the Helvetica font.
+# If you specify a different font using DOT_FONTNAME you can use DOT_FONTPATH to
+# set the path where dot can find it.
+
+DOT_FONTPATH           =
+
+# If the CLASS_GRAPH and HAVE_DOT tags are 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.
+
+CLASS_GRAPH            = YES
+
+# If the COLLABORATION_GRAPH and HAVE_DOT tags are set to YES then doxygen
+# will generate a graph for each documented class showing the direct and
+# indirect implementation dependencies (inheritance, containment, and
+# class references variables) of the class with other documented classes.
+
+COLLABORATION_GRAPH    = YES
+
+# If the GROUP_GRAPHS and HAVE_DOT tags are set to YES then doxygen
+# will generate a graph for groups, showing the direct groups dependencies
+
+GROUP_GRAPHS           = YES
+
+# If the UML_LOOK tag is set to YES doxygen will generate inheritance and
+# collaboration diagrams in a style similar to the OMG's Unified Modeling
+# Language.
+
+UML_LOOK               = NO
+
+# If the UML_LOOK tag is enabled, the fields and methods are shown inside
+# the class node. If there are many fields or methods and many nodes the
+# graph may become too big to be useful. The UML_LIMIT_NUM_FIELDS
+# threshold limits the number of items for each type to make the size more
+# managable. Set this to 0 for no limit. Note that the threshold may be
+# exceeded by 50% before the limit is enforced.
+
+UML_LIMIT_NUM_FIELDS   = 10
+
+# If set to YES, the inheritance and collaboration graphs will show the
+# relations between templates and their instances.
+
+TEMPLATE_RELATIONS     = NO
+
+# If the ENABLE_PREPROCESSING, SEARCH_INCLUDES, INCLUDE_GRAPH, and HAVE_DOT
+# tags are set to YES then doxygen will generate a graph for each documented
+# file showing the direct and indirect include dependencies of the file with
+# other documented files.
+
+INCLUDE_GRAPH          = YES
+
+# If the ENABLE_PREPROCESSING, SEARCH_INCLUDES, INCLUDED_BY_GRAPH, and
+# HAVE_DOT tags are set to YES then doxygen will generate a graph for each
+# documented header file showing the documented files that directly or
+# indirectly include this file.
+
+INCLUDED_BY_GRAPH      = YES
+
+# If the CALL_GRAPH and HAVE_DOT options are set to YES then
+# doxygen will generate a call dependency graph for every global function
+# or class method. Note that enabling this option will significantly increase
+# the time of a run. So in most cases it will be better to enable call graphs
+# for selected functions only using the \callgraph command.
+
+CALL_GRAPH             = NO
+
+# If the CALLER_GRAPH and HAVE_DOT tags are set to YES then
+# doxygen will generate a caller dependency graph for every global function
+# or class method. Note that enabling this option will significantly increase
+# the time of a run. So in most cases it will be better to enable caller
+# graphs for selected functions only using the \callergraph command.
+
+CALLER_GRAPH           = NO
+
+# If the GRAPHICAL_HIERARCHY and HAVE_DOT tags are set to YES then doxygen
+# will generate a graphical hierarchy of all classes instead of a textual one.
+
+GRAPHICAL_HIERARCHY    = YES
+
+# If the DIRECTORY_GRAPH and HAVE_DOT tags are set to YES
+# then doxygen will show the dependencies a directory has on other directories
+# in a graphical way. The dependency relations are determined by the #include
+# relations between the files in the directories.
+
+DIRECTORY_GRAPH        = YES
+
+# The DOT_IMAGE_FORMAT tag can be used to set the image format of the images
+# generated by dot. Possible values are svg, png, jpg, or gif.
+# If left blank png will be used. 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).
+
+DOT_IMAGE_FORMAT       = png
+
+# If DOT_IMAGE_FORMAT is set to svg, then this option can be set to YES to
+# enable generation of interactive SVG images that allow zooming and panning.
+# Note that this requires a modern browser other than Internet Explorer.
+# Tested and working are Firefox, Chrome, Safari, and Opera. For IE 9+ you
+# need to set HTML_FILE_EXTENSION to xhtml in order to make the SVG files
+# visible. Older versions of IE do not have SVG support.
+
+INTERACTIVE_SVG        = NO
+
+# The tag DOT_PATH can be used to specify the path where the dot tool can be
+# found. If left blank, it is assumed the dot tool can be found in the path.
+
+DOT_PATH               =
+
+# The DOTFILE_DIRS tag can be used to specify one or more directories that
+# contain dot files that are included in the documentation (see the
+# \dotfile command).
+
+DOTFILE_DIRS           =
+
+# The MSCFILE_DIRS tag can be used to specify one or more directories that
+# contain msc files that are included in the documentation (see the
+# \mscfile command).
+
+MSCFILE_DIRS           =
+
+# The DOT_GRAPH_MAX_NODES tag can be used to set the maximum number of
+# nodes that will be shown in the graph. If the number of nodes in a graph
+# becomes larger than this value, doxygen will truncate the graph, which is
+# visualized by representing a node as a red box. Note that doxygen if the
+# number of direct children of the root node in a graph is already larger than
+# DOT_GRAPH_MAX_NODES then the graph will not be shown at all. Also note
+# that the size of a graph can be further restricted by MAX_DOT_GRAPH_DEPTH.
+
+DOT_GRAPH_MAX_NODES    = 50
+
+# The MAX_DOT_GRAPH_DEPTH tag can be used to set the maximum depth of the
+# graphs generated by dot. A depth value of 3 means that only nodes reachable
+# from the root by following a path via at most 3 edges will be shown. Nodes
+# that lay further from the root node will be omitted. Note that setting this
+# option to 1 or 2 may greatly reduce the computation time needed for large
+# code bases. Also note that the size of a graph can be further restricted by
+# DOT_GRAPH_MAX_NODES. Using a depth of 0 means no depth restriction.
+
+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).
+
+DOT_TRANSPARENT        = NO
+
+# Set the DOT_MULTI_TARGETS tag to YES 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 this, this feature is disabled by default.
+
+DOT_MULTI_TARGETS      = YES
+
+# If the GENERATE_LEGEND tag is set to YES (the default) Doxygen will
+# generate a legend page explaining the meaning of the various boxes and
+# arrows in the dot generated graphs.
+
+GENERATE_LEGEND        = YES
+
+# If the DOT_CLEANUP tag is set to YES (the default) Doxygen will
+# remove the intermediate dot files that are used to generate
+# the various graphs.
+
+DOT_CLEANUP            = YES
diff --git a/include/libnsgif.h b/include/libnsgif.h
index 462c354..33b4b19 100644
--- a/include/libnsgif.h
+++ b/include/libnsgif.h
@@ -7,8 +7,9 @@
  *                http://www.opensource.org/licenses/mit-license.php
  */
 
-/** \file
- * Progressive animated GIF file decoding (interface).
+/**
+ * \file
+ * Interface to progressive animated GIF file decoding.
  */
 
 #ifndef _LIBNSGIF_H_
@@ -17,42 +18,53 @@
 #include <stdbool.h>
 #include <inttypes.h>
 
-/*	Error return values
-*/
+/* Error return values */
 typedef enum {
-	GIF_WORKING = 1,
-	GIF_OK = 0,
-	GIF_INSUFFICIENT_FRAME_DATA = -1,
-	GIF_FRAME_DATA_ERROR = -2,
-	GIF_INSUFFICIENT_DATA = -3,
-	GIF_DATA_ERROR = -4,
-	GIF_INSUFFICIENT_MEMORY = -5,
-	GIF_FRAME_NO_DISPLAY = -6,
-	GIF_END_OF_FRAME = -7
+        GIF_WORKING = 1,
+        GIF_OK = 0,
+        GIF_INSUFFICIENT_FRAME_DATA = -1,
+        GIF_FRAME_DATA_ERROR = -2,
+        GIF_INSUFFICIENT_DATA = -3,
+        GIF_DATA_ERROR = -4,
+        GIF_INSUFFICIENT_MEMORY = -5,
+        GIF_FRAME_NO_DISPLAY = -6,
+        GIF_END_OF_FRAME = -7
 } gif_result;
 
-/*	The GIF frame data
-*/
+/** GIF frame data */
 typedef struct gif_frame {
-  	bool display;				/**< whether the frame should be displayed/animated */
-  	unsigned int frame_delay;		/**< delay (in cs) before animating the frame */
-	/**	Internal members are listed below
-	*/
-  	unsigned int frame_pointer;		/**< offset (in bytes) to the GIF frame data */
-  	bool virgin;				/**< whether the frame has previously been used */
-	bool opaque;				/**< whether the frame is totally opaque */
-	bool redraw_required;			/**< whether a forcable screen redraw is required */
-	unsigned char disposal_method;		/**< how the previous frame should be disposed; affects plotting */
-	bool transparency;	 		/**< whether we acknoledge transparency */
-	unsigned char transparency_index;	/**< the index designating a transparent pixel */
-	unsigned int redraw_x;			/**< x co-ordinate of redraw rectangle */
-	unsigned int redraw_y;			/**< y co-ordinate of redraw rectangle */
-	unsigned int redraw_width;		/**< width of redraw rectangle */
-	unsigned int redraw_height;		/**< height of redraw rectangle */
+        /** whether the frame should be displayed/animated */
+        bool display;
+        /** delay (in cs) before animating the frame */
+        unsigned int frame_delay;
+
+        /* Internal members are listed below */
+
+        /** offset (in bytes) to the GIF frame data */
+        unsigned int frame_pointer;
+        /** whether the frame has previously been used */
+        bool virgin;
+        /** whether the frame is totally opaque */
+        bool opaque;
+        /** whether a forcable screen redraw is required */
+        bool redraw_required;
+        /** how the previous frame should be disposed; affects plotting */
+        unsigned char disposal_method;
+        /** whether we acknoledge transparency */
+        bool transparency;
+        /** the index designating a transparent pixel */
+        unsigned char transparency_index;
+        /** x co-ordinate of redraw rectangle */
+        unsigned int redraw_x;
+        /** y co-ordinate of redraw rectangle */
+        unsigned int redraw_y;
+        /** width of redraw rectangle */
+        unsigned int redraw_width;
+        /** height of redraw rectangle */
+        unsigned int redraw_height;
 } gif_frame;
 
-/*	API for Bitmap callbacks
-*/
+/* API for Bitmap callbacks */
 typedef void* (*gif_bitmap_cb_create)(int width, int height);
 typedef void (*gif_bitmap_cb_destroy)(void *bitmap);
 typedef unsigned char* (*gif_bitmap_cb_get_buffer)(void *bitmap);
@@ -60,49 +72,112 @@ typedef void (*gif_bitmap_cb_set_opaque)(void *bitmap, bool opaque);
 typedef bool (*gif_bitmap_cb_test_opaque)(void *bitmap);
 typedef void (*gif_bitmap_cb_modified)(void *bitmap);
 
-/*	The Bitmap callbacks function table
-*/
+/** Bitmap callbacks function table */
 typedef struct gif_bitmap_callback_vt {
-	gif_bitmap_cb_create bitmap_create;		/**< Create a bitmap. */
-	gif_bitmap_cb_destroy bitmap_destroy;		/**< Free a bitmap. */
-	gif_bitmap_cb_get_buffer bitmap_get_buffer;	/**< Return a pointer to the pixel data in a bitmap. */
-	/**	Members below are optional
-	*/
-	gif_bitmap_cb_set_opaque bitmap_set_opaque;	/**< Sets whether a bitmap should be plotted opaque. */
-	gif_bitmap_cb_test_opaque bitmap_test_opaque;	/**< Tests whether a bitmap has an opaque alpha channel. */
-	gif_bitmap_cb_modified bitmap_modified;	/**< The bitmap image has changed, so flush any persistant cache. */
+        /** Create a bitmap. */
+        gif_bitmap_cb_create bitmap_create;
+        /** Free a bitmap. */
+        gif_bitmap_cb_destroy bitmap_destroy;
+        /** Return a pointer to the pixel data in a bitmap. */
+        gif_bitmap_cb_get_buffer bitmap_get_buffer;
+
+        /* Members below are optional */
+
+        /** Sets whether a bitmap should be plotted opaque. */
+        gif_bitmap_cb_set_opaque bitmap_set_opaque;
+        /** Tests whether a bitmap has an opaque alpha channel. */
+        gif_bitmap_cb_test_opaque bitmap_test_opaque;
+        /** The bitmap image has changed, so flush any persistant cache. */
+        gif_bitmap_cb_modified bitmap_modified;
 } gif_bitmap_callback_vt;
 
-/*	The GIF animation data
-*/
+/** GIF animation data */
 typedef struct gif_animation {
-	gif_bitmap_callback_vt bitmap_callbacks;	/**< callbacks for bitmap functions */
-	unsigned char *gif_data;			/**< pointer to GIF data */
-	unsigned int width;				/**< width of GIF (may increase during decoding) */
-	unsigned int height;				/**< heigth of GIF (may increase during decoding) */
-	unsigned int frame_count;			/**< number of frames decoded */
-	unsigned int frame_count_partial;		/**< number of frames partially decoded */
-	gif_frame *frames;				/**< decoded frames */
-	int decoded_frame;				/**< current frame decoded to bitmap */
-	void *frame_image;				/**< currently decoded image; stored as bitmap from bitmap_create callback */
-	int loop_count;					/**< number of times to loop animation */
-	gif_result current_error;			/**< current error type, or 0 for none*/
-	/**	Internal members are listed below
-	*/
-	unsigned int buffer_position;			/**< current index into GIF data */
-	unsigned int buffer_size;			/**< total number of bytes of GIF data available */
-	unsigned int frame_holders;			/**< current number of frame holders */
-	unsigned int background_index;			/**< index in the colour table for the background colour */
-	unsigned int aspect_ratio;			/**< image aspect ratio (ignored) */
-	unsigned int colour_table_size;		/**< size of colour table (in entries) */
-	bool global_colours;				/**< whether the GIF has a global colour table */
-	unsigned int *global_colour_table;		/**< global colour table */
-	unsigned int *local_colour_table;		/**< local colour table */
+        /** callbacks for bitmap functions */
+        gif_bitmap_callback_vt bitmap_callbacks;
+        /** pointer to GIF data */
+        unsigned char *gif_data;
+        /** width of GIF (may increase during decoding) */
+        unsigned int width;
+        /** heigth of GIF (may increase during decoding) */
+        unsigned int height;
+        /** number of frames decoded */
+        unsigned int frame_count;
+        /** number of frames partially decoded */
+        unsigned int frame_count_partial;
+        /** decoded frames */
+        gif_frame *frames;
+        /** current frame decoded to bitmap */
+        int decoded_frame;
+        /** currently decoded image; stored as bitmap from bitmap_create callback */
+        void *frame_image;
+        /** number of times to loop animation */
+        int loop_count;
+        /** current error type, or 0 for none */
+        gif_result current_error;
+
+        /* Internal members are listed below */
+
+        /** current index into GIF data */
+        unsigned int buffer_position;
+        /** total number of bytes of GIF data available */
+        unsigned int buffer_size;
+        /** current number of frame holders */
+        unsigned int frame_holders;
+        /** index in the colour table for the background colour */
+        unsigned int background_index;
+        /** image aspect ratio (ignored) */
+        unsigned int aspect_ratio;
+        /** size of colour table (in entries) */
+        unsigned int colour_table_size;
+        /** whether the GIF has a global colour table */
+        bool global_colours;
+        /** global colour table */
+        unsigned int *global_colour_table;
+        /** local colour table */
+        unsigned int *local_colour_table;
 } gif_animation;
 
+/**
+ * Initialises necessary gif_animation members.
+ */
 void gif_create(gif_animation *gif, gif_bitmap_callback_vt *bitmap_callbacks);
+
+/**
+ * Initialises any workspace held by the animation and attempts to decode
+ * any information that hasn't already been decoded.
+ * If an error occurs, all previously decoded frames are retained.
+ *
+ * @return Error return value.
+ *         - GIF_FRAME_DATA_ERROR for GIF frame data error
+ *         - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to process
+ *                                     any more frames
+ *         - GIF_INSUFFICIENT_MEMORY for memory error
+ *         - GIF_DATA_ERROR for GIF error
+ *         - GIF_INSUFFICIENT_DATA for insufficient data to do anything
+ *         - GIF_OK for successful decoding
+ *         - GIF_WORKING for successful decoding if more frames are expected
+ */
 gif_result gif_initialise(gif_animation *gif, size_t size, unsigned char *data);
+
+/**
+ * Decodes a GIF frame.
+ *
+ * @return Error return value. If a frame does not contain any image data,
+ *		GIF_OK is returned and gif->current_error is set to
+ *		GIF_FRAME_NO_DISPLAY
+ *         - GIF_FRAME_DATA_ERROR for GIF frame data error
+ *         - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
+ *         - GIF_DATA_ERROR for GIF error (invalid frame header)
+ *         - GIF_INSUFFICIENT_DATA for insufficient data to do anything
+ *         - GIF_INSUFFICIENT_MEMORY for insufficient memory to process
+ *         - GIF_OK for successful decoding
+ */
 gif_result gif_decode_frame(gif_animation *gif, unsigned int frame);
+
+/**
+ * Releases any workspace held by a gif
+ */
 void gif_finalise(gif_animation *gif);
 
 #endif
diff --git a/src/libnsgif.c b/src/libnsgif.c
index 87371f2..69c54ea 100644
--- a/src/libnsgif.c
+++ b/src/libnsgif.c
@@ -15,82 +15,39 @@
 #include "libnsgif.h"
 #include "utils/log.h"
 
-/*	READING GIF FILES
-	=================
-
-	The functions provided by this file allow for efficient progressive GIF
-	decoding. Whilst the initialisation does not ensure that there is
-	sufficient image data to complete the entire frame, it does ensure that
-	the information provided is valid. Any subsequent attempts to decode an
-	initialised GIF are guaranteed to succeed, and any bytes of the image
-	not present are assumed to be totally transparent.
-
-	To begin decoding a GIF, the 'gif' structure must be initialised with
-	the 'gif_data' and 'buffer_size' set to their initial values. The
-	'buffer_position' should initially be 0, and will be internally updated
-	as the decoding commences. The caller should then repeatedly call
-	gif_initialise() with the structure until the function returns 1, or
-	no more data is avaliable.
-
-	Once the initialisation has begun, the decoder completes the variables
-	'frame_count' and 'frame_count_partial'. The former being the total
-	number of frames that have been successfully initialised, and the
-	latter being the number of frames that a partial amount of data is
-	available for. This assists the caller in managing the animation whilst
-	decoding is continuing.
-
-	To decode a frame, the caller must use gif_decode_frame() which updates
-	the current 'frame_image' to reflect the desired frame. The required
-	'disposal_method' is also updated to reflect how the frame should be
-	plotted. The caller must not assume that the current 'frame_image' will
-	be valid between calls if initialisation is still occuring, and should
-	either always request that the frame is decoded (no processing will
-	occur if the 'decoded_frame' has not been invalidated by initialisation)
-	or perform the check itself.
-
-	It should be noted that gif_finalise() should always be called, even if
-	no frames were initialised.  Additionally, it is the responsibility of
-	the caller to free 'gif_data'.
-
-	[rjw] - Fri 2nd April 2004
-*/
-
-/*	TO-DO LIST
-	=================
-
-	+ Plain text and comment extensions could be implemented if there is any
-	interest in doing so.
-*/
-
-
+/**
+ *
+ * \file
+ * \brief GIF image decoder
+ *
+ * The GIF format is thoroughly documented; a full description can be found at
+ * http://www.w3.org/Graphics/GIF/spec-gif89a.txt
+ *
+ * \todo Plain text and comment extensions should be implemented.
+ */
 
 
-/*	Maximum colour table size
-*/
+/** Maximum colour table size */
 #define GIF_MAX_COLOURS 256
 
-/*	Internal flag that the colour table needs to be processed
-*/
+/** Internal flag that the colour table needs to be processed */
 #define GIF_PROCESS_COLOURS 0xaa000000
 
-/*	Internal flag that a frame is invalid/unprocessed
-*/
+/** Internal flag that a frame is invalid/unprocessed */
 #define GIF_INVALID_FRAME -1
 
-/*	Maximum LZW bits available
-*/
+/** Maximum LZW bits available */
 #define GIF_MAX_LZW 12
 
-/* Transparent colour
-*/
+/** Transparent colour */
 #define GIF_TRANSPARENT_COLOUR 0x00
 
-/*	GIF Flags
-*/
+/* GIF Flags */
 #define GIF_FRAME_COMBINE 1
 #define GIF_FRAME_CLEAR 2
 #define GIF_FRAME_RESTORE 3
 #define GIF_FRAME_QUIRKS_RESTORE 4
+
 #define GIF_IMAGE_SEPARATOR 0x2c
 #define GIF_INTERLACE_MASK 0x40
 #define GIF_COLOUR_TABLE_MASK 0x80
@@ -105,30 +62,28 @@
 #define GIF_BLOCK_TERMINATOR 0x00
 #define GIF_TRAILER 0x3b
 
-/*	Internal GIF routines
-*/
+/* Internal GIF routines */
 static gif_result gif_initialise_sprite(gif_animation *gif, unsigned int width, unsigned int height);
 static gif_result gif_initialise_frame(gif_animation *gif);
 static gif_result gif_initialise_frame_extensions(gif_animation *gif, const int frame);
 static gif_result gif_skip_frame_extensions(gif_animation *gif);
 static unsigned int gif_interlaced_line(int height, int y);
 
-
-
-/*	Internal LZW routines
-*/
+/* Internal LZW routines */
 static void gif_init_LZW(gif_animation *gif);
 static bool gif_next_LZW(gif_animation *gif);
 static int gif_next_code(gif_animation *gif, int code_size);
 
-/*	General LZW values. They are shared for all GIFs being decoded, and
-	thus we can't handle progressive decoding efficiently without having
-	the data for each image which would use an extra 10Kb or so per GIF.
-*/
+/* General LZW values. They are shared for all GIFs being decoded, and thus we
+ * can't handle progressive decoding efficiently without having the data for
+ * each image which would use an extra 10Kb or so per GIF.
+ */
 static unsigned char buf[4];
 static unsigned char *direct;
-static int maskTbl[16] = {0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f,
-			  0x00ff, 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff};
+static int maskTbl[16] = {
+        0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f,
+        0x00ff, 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff
+};
 static int table[2][(1 << GIF_MAX_LZW)];
 static unsigned char stack[(1 << GIF_MAX_LZW) * 2];
 static unsigned char *stack_pointer;
@@ -140,1181 +95,1246 @@ static int firstcode, oldcode;
 static bool zero_data_block = false;
 static bool get_done;
 
-/*	Whether to clear the decoded image rather than plot
-*/
+/* Whether to clear the decoded image rather than plot */
 static bool clear_image = false;
 
 
-
-/**	Initialises necessary gif_animation members.
-*/
-void gif_create(gif_animation *gif, gif_bitmap_callback_vt *bitmap_callbacks) {
-	memset(gif, 0, sizeof(gif_animation));
-	gif->bitmap_callbacks = *bitmap_callbacks;
-	gif->decoded_frame = GIF_INVALID_FRAME;
+/**
+ * Updates the sprite memory size
+ *
+ * \param gif The animation context
+ * \param width The width of the sprite
+ * \param height The height of the sprite
+ * \return GIF_INSUFFICIENT_MEMORY for a memory error GIF_OK for success
+ */
+static gif_result
+gif_initialise_sprite(gif_animation *gif,
+                      unsigned int width,
+                      unsigned int height)
+{
+        unsigned int max_width;
+        unsigned int max_height;
+        struct bitmap *buffer;
+
+        /* Check if we've changed */
+        if ((width <= gif->width) && (height <= gif->height)) {
+                return GIF_OK;
+        }
+
+        /* Get our maximum values */
+        max_width = (width > gif->width) ? width : gif->width;
+        max_height = (height > gif->height) ? height : gif->height;
+
+        /* Allocate some more memory */
+        assert(gif->bitmap_callbacks.bitmap_create);
+        buffer = gif->bitmap_callbacks.bitmap_create(max_width, max_height);
+        if (buffer == NULL) {
+                return GIF_INSUFFICIENT_MEMORY;
+        }
+
+        assert(gif->bitmap_callbacks.bitmap_destroy);
+        gif->bitmap_callbacks.bitmap_destroy(gif->frame_image);
+        gif->frame_image = buffer;
+        gif->width = max_width;
+        gif->height = max_height;
+
+        /* Invalidate our currently decoded image */
+        gif->decoded_frame = GIF_INVALID_FRAME;
+        return GIF_OK;
 }
 
 
-/**	Initialises any workspace held by the animation and attempts to decode
-	any information that hasn't already been decoded.
-	If an error occurs, all previously decoded frames are retained.
-
-	@return GIF_FRAME_DATA_ERROR for GIF frame data error
-		GIF_INSUFFICIENT_FRAME_DATA for insufficient data to process
-		          any more frames
-		GIF_INSUFFICIENT_MEMORY for memory error
-		GIF_DATA_ERROR for GIF error
-		GIF_INSUFFICIENT_DATA for insufficient data to do anything
-		GIF_OK for successful decoding
-		GIF_WORKING for successful decoding if more frames are expected
+/**
+ * Attempts to initialise the next frame
+ *
+ * \param gif The animation context
+ * \return error code
+ *         - GIF_INSUFFICIENT_DATA for insufficient data to do anything
+ *         - GIF_FRAME_DATA_ERROR for GIF frame data error
+ *         - GIF_INSUFFICIENT_MEMORY for insufficient memory to process
+ *         - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
+ *         - GIF_DATA_ERROR for GIF error (invalid frame header)
+ *         - GIF_OK for successful decoding
+ *         - GIF_WORKING for successful decoding if more frames are expected
 */
-gif_result gif_initialise(gif_animation *gif, size_t size, unsigned char *data) {
-	unsigned char *gif_data;
-	unsigned int index;
-	gif_result return_value;
-
-	/* 	The GIF format is thoroughly documented; a full description
-	 *	can be found at http://www.w3.org/Graphics/GIF/spec-gif89a.txt
-	*/
-
-	/*	Initialize values
-	*/
-	gif->buffer_size = size;
-	gif->gif_data = data;
-	
-	/*	Check for sufficient data to be a GIF (6-byte header + 7-byte logical screen descriptor)
-	*/
-	if (gif->buffer_size < 13) return GIF_INSUFFICIENT_DATA;
-
-	/*	Get our current processing position
-	*/
-	gif_data = gif->gif_data + gif->buffer_position;
-
-	/*	See if we should initialise the GIF
-	*/
-	if (gif->buffer_position == 0) {
-
-		/*	We want everything to be NULL before we start so we've no chance
-			of freeing bad pointers (paranoia)
-		*/
-		gif->frame_image = NULL;
-		gif->frames = NULL;
-		gif->local_colour_table = NULL;
-		gif->global_colour_table = NULL;
-
-		/*	The caller may have been lazy and not reset any values
-		*/
-		gif->frame_count = 0;
-		gif->frame_count_partial = 0;
-		gif->decoded_frame = GIF_INVALID_FRAME;
-
-		/* 6-byte GIF file header is:
-		 *
-		 *	+0	3CHARS	Signature ('GIF')
-		 *	+3	3CHARS	Version ('87a' or '89a')
-		 */
-		if (strncmp((const char *) gif_data, "GIF", 3) != 0)
-			return GIF_DATA_ERROR;
-		gif_data += 3;
-
-		/*	Ensure GIF reports version 87a or 89a
-		*/
-/*		if ((strncmp(gif_data, "87a", 3) != 0) &&
-				(strncmp(gif_data, "89a", 3) != 0))
-			LOG(("Unknown GIF format - proceeding anyway"));
-*/		gif_data += 3;
-
-		/* 7-byte Logical Screen Descriptor is:
-		 *
-		 *	+0	SHORT	Logical Screen Width
-		 *	+2	SHORT	Logical Screen Height
-		 *	+4	CHAR	__Packed Fields__
-		 * 			1BIT	Global Colour Table Flag
-		 * 			3BITS	Colour Resolution
-		 * 			1BIT	Sort Flag
-		 * 			3BITS	Size of Global Colour Table
-		 *	+5	CHAR	Background Colour Index
-		 *	+6	CHAR	Pixel Aspect Ratio
-		 */
-		gif->width = gif_data[0] | (gif_data[1] << 8);
-		gif->height = gif_data[2] | (gif_data[3] << 8);
-		gif->global_colours = (gif_data[4] & GIF_COLOUR_TABLE_MASK);
-		gif->colour_table_size = (2 << (gif_data[4] & GIF_COLOUR_TABLE_SIZE_MASK));
-		gif->background_index = gif_data[5];
-		gif->aspect_ratio = gif_data[6];
-		gif->loop_count = 1;
-		gif_data += 7;
-
-		/*	Some broken GIFs report the size as the screen size they were created in. As
-			such, we detect for the common cases and set the sizes as 0 if they are found
-			which results in the GIF being the maximum size of the frames.
-		*/
-		if (((gif->width == 640) && (gif->height == 480)) ||
-				((gif->width == 640) && (gif->height == 512)) ||
-				((gif->width == 800) && (gif->height == 600)) ||
-				((gif->width == 1024) && (gif->height == 768)) ||
-				((gif->width == 1280) && (gif->height == 1024)) ||
-				((gif->width == 1600) && (gif->height == 1200)) ||
-				((gif->width == 0) || (gif->height == 0)) ||
-				((gif->width > 2048) || (gif->height > 2048))) {
-			gif->width = 1;
-			gif->height = 1;
-		}
-
-		/*	Allocate some data irrespective of whether we've got any colour tables. We
-			always get the maximum size in case a GIF is lying to us. It's far better
-			to give the wrong colours than to trample over some memory somewhere.
-		*/
-		gif->global_colour_table = calloc(GIF_MAX_COLOURS, sizeof(unsigned int));
-		gif->local_colour_table = calloc(GIF_MAX_COLOURS, sizeof(unsigned int));
-		if ((gif->global_colour_table == NULL) || (gif->local_colour_table == NULL)) {
-			gif_finalise(gif);
-			return GIF_INSUFFICIENT_MEMORY;
-		}
-
-		/*	Set the first colour to a value that will never occur in reality so we
-			know if we've processed it
-		*/
-		gif->global_colour_table[0] = GIF_PROCESS_COLOURS;
-		
-		/*	Check if the GIF has no frame data (13-byte header + 1-byte termination block)
-		 *	Although generally useless, the GIF specification does not expressly prohibit this
-		 */
-		if (gif->buffer_size == 14) {
-			if (gif_data[0] == GIF_TRAILER)
-				return GIF_OK;
-			else
-				return GIF_INSUFFICIENT_DATA;
-		}
-
-		/*	Initialise enough workspace for 4 frames initially
-		*/
-		if ((gif->frames = (gif_frame *)malloc(sizeof(gif_frame))) == NULL) {
-			gif_finalise(gif);
-			return GIF_INSUFFICIENT_MEMORY;
-		}
-		gif->frame_holders = 1;
-
-		/*	Initialise the sprite header
-		*/
-		assert(gif->bitmap_callbacks.bitmap_create);
-		if ((gif->frame_image = gif->bitmap_callbacks.bitmap_create(gif->width, gif->height)) == NULL) {
-			gif_finalise(gif);
-			return GIF_INSUFFICIENT_MEMORY;
-		}
-
-		/*	Remember we've done this now
-		*/
-		gif->buffer_position = gif_data - gif->gif_data;
-	}
-
-	/*	Do the colour map if we haven't already. As the top byte is always 0xff or 0x00
-		depending on the transparency we know if it's been filled in.
-	*/
-	if (gif->global_colour_table[0] == GIF_PROCESS_COLOURS) {
-		/*	Check for a global colour map signified by bit 7
-		*/
-		if (gif->global_colours) {
-			if (gif->buffer_size < (gif->colour_table_size * 3 + 12)) {
-				return GIF_INSUFFICIENT_DATA;
-			}
-			for (index = 0; index < gif->colour_table_size; index++) {
-				/* Gif colour map contents are r,g,b.
-				 *
-				 * We want to pack them bytewise into the 
-				 * colour table, such that the red component
-				 * is in byte 0 and the alpha component is in
-				 * byte 3.
-				 */
-				unsigned char *entry = (unsigned char *) &gif->
-						global_colour_table[index];
-
-				entry[0] = gif_data[0];	/* r */
-				entry[1] = gif_data[1];	/* g */
-				entry[2] = gif_data[2];	/* b */
-				entry[3] = 0xff;	/* a */
-
-				gif_data += 3;
-			}
-			gif->buffer_position = (gif_data - gif->gif_data);
-		} else {
-			/*	Create a default colour table with the first two colours as black and white
-			*/
-			unsigned int *entry = gif->global_colour_table;
-
-			entry[0] = 0x00000000;
-			/* Force Alpha channel to opaque */
-			((unsigned char *) entry)[3] = 0xff;
-
-			entry[1] = 0xffffffff;
-		}
-	}
-
-	/*	Repeatedly try to initialise frames
-	*/
-	while ((return_value = gif_initialise_frame(gif)) == GIF_WORKING);
-
-	/*	If there was a memory error tell the caller
-	*/
-	if ((return_value == GIF_INSUFFICIENT_MEMORY) ||
-			(return_value == GIF_DATA_ERROR))
-		return return_value;
-
-	/*	If we didn't have some frames then a GIF_INSUFFICIENT_DATA becomes a
-		GIF_INSUFFICIENT_FRAME_DATA
-	*/
-	if ((return_value == GIF_INSUFFICIENT_DATA) && (gif->frame_count_partial > 0))
-		return GIF_INSUFFICIENT_FRAME_DATA;
-
-	/*	Return how many we got
-	*/
-	return return_value;
+static gif_result gif_initialise_frame(gif_animation *gif)
+{
+        int frame;
+        gif_frame *temp_buf;
+
+        unsigned char *gif_data, *gif_end;
+        int gif_bytes;
+        unsigned int flags = 0;
+        unsigned int width, height, offset_x, offset_y;
+        unsigned int block_size, colour_table_size;
+        bool first_image = true;
+        gif_result return_value;
+
+        /* Get the frame to decode and our data position */
+        frame = gif->frame_count;
+
+        /* Get our buffer position etc. */
+        gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position);
+        gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size);
+        gif_bytes = (gif_end - gif_data);
+
+        /* Check if we've finished */
+        if ((gif_bytes > 0) && (gif_data[0] == GIF_TRAILER)) {
+                return GIF_OK;
+        }
+
+        /* Check if there is enough data remaining. The shortest block of data
+         * is a 4-byte comment extension + 1-byte block terminator + 1-byte gif
+         * trailer
+         */
+        if (gif_bytes < 6) {
+                return GIF_INSUFFICIENT_DATA;
+        }
+
+        /* We could theoretically get some junk data that gives us millions of
+         * frames, so we ensure that we don't have a silly number
+         */
+        if (frame > 4096) {
+                return GIF_FRAME_DATA_ERROR;
+        }
+
+        /* Get some memory to store our pointers in etc. */
+        if ((int)gif->frame_holders <= frame) {
+                /* Allocate more memory */
+                temp_buf = (gif_frame *)realloc(gif->frames, (frame + 1) * sizeof(gif_frame));
+                if (temp_buf == NULL) {
+                        return GIF_INSUFFICIENT_MEMORY;
+                }
+                gif->frames = temp_buf;
+                gif->frame_holders = frame + 1;
+        }
+
+        /* Store our frame pointer. We would do it when allocating except we
+         * start off with one frame allocated so we can always use realloc.
+         */
+        gif->frames[frame].frame_pointer = gif->buffer_position;
+        gif->frames[frame].display = false;
+        gif->frames[frame].virgin = true;
+        gif->frames[frame].disposal_method = 0;
+        gif->frames[frame].transparency = false;
+        gif->frames[frame].frame_delay = 100;
+        gif->frames[frame].redraw_required = false;
+
+        /* Invalidate any previous decoding we have of this frame */
+        if (gif->decoded_frame == frame) {
+                gif->decoded_frame = GIF_INVALID_FRAME;
+        }
+
+        /* We pretend to initialise the frames, but really we just skip over
+         * all the data contained within. This is all basically a cut down
+         * version of gif_decode_frame that doesn't have any of the LZW bits in
+         * it.
+         */
+
+        /* Initialise any extensions */
+        gif->buffer_position = gif_data - gif->gif_data;
+        return_value = gif_initialise_frame_extensions(gif, frame);
+        if (return_value != GIF_OK) {
+                return return_value;
+        }
+        gif_data = (gif->gif_data + gif->buffer_position);
+        gif_bytes = (gif_end - gif_data);
+
+        /* Check if we've finished */
+        if ((gif_bytes = (gif_end - gif_data)) < 1) {
+                return GIF_INSUFFICIENT_FRAME_DATA;
+        }
+
+        if (gif_data[0] == GIF_TRAILER) {
+                gif->buffer_position = (gif_data - gif->gif_data);
+                gif->frame_count = frame + 1;
+                return GIF_OK;
+        }
+
+        /* If we're not done, there should be an image descriptor */
+        if (gif_data[0] != GIF_IMAGE_SEPARATOR) {
+                return GIF_FRAME_DATA_ERROR;
+        }
+
+        /* Do some simple boundary checking */
+        if (gif_bytes < 10) {
+                return GIF_INSUFFICIENT_FRAME_DATA;
+        }
+        offset_x = gif_data[1] | (gif_data[2] << 8);
+        offset_y = gif_data[3] | (gif_data[4] << 8);
+        width = gif_data[5] | (gif_data[6] << 8);
+        height = gif_data[7] | (gif_data[8] << 8);
+
+        /* Set up the redraw characteristics. We have to check for extending
+         * the area due to multi-image frames.
+         */
+        if (!first_image) {
+                if (gif->frames[frame].redraw_x > offset_x) {
+                        gif->frames[frame].redraw_width += (gif->frames[frame].redraw_x - offset_x);
+                        gif->frames[frame].redraw_x = offset_x;
+                }
+
+                if (gif->frames[frame].redraw_y > offset_y) {
+                        gif->frames[frame].redraw_height += (gif->frames[frame].redraw_y - offset_y);
+                        gif->frames[frame].redraw_y = offset_y;
+                }
+
+                if ((offset_x + width) > (gif->frames[frame].redraw_x + gif->frames[frame].redraw_width)) {
+                        gif->frames[frame].redraw_width = (offset_x + width) - gif->frames[frame].redraw_x;
+                }
+
+                if ((offset_y + height) > (gif->frames[frame].redraw_y + gif->frames[frame].redraw_height)) {
+                        gif->frames[frame].redraw_height = (offset_y + height) - gif->frames[frame].redraw_y;
+                }
+        } else {
+                first_image = false;
+                gif->frames[frame].redraw_x = offset_x;
+                gif->frames[frame].redraw_y = offset_y;
+                gif->frames[frame].redraw_width = width;
+                gif->frames[frame].redraw_height = height;
+        }
+
+        /* if we are clearing the background then we need to redraw enough to
+         * cover the previous frame too
+         */
+        gif->frames[frame].redraw_required = ((gif->frames[frame].disposal_method == GIF_FRAME_CLEAR) ||
+                                                (gif->frames[frame].disposal_method == GIF_FRAME_RESTORE));
+
+        /* Boundary checking - shouldn't ever happen except with junk data */
+        if (gif_initialise_sprite(gif, (offset_x + width), (offset_y + height))) {
+                return GIF_INSUFFICIENT_MEMORY;
+        }
+
+        /* Decode the flags */
+        flags = gif_data[9];
+        colour_table_size = 2 << (flags & GIF_COLOUR_TABLE_SIZE_MASK);
+
+        /* Move our data onwards and remember we've got a bit of this frame */
+        gif_data += 10;
+        gif_bytes = (gif_end - gif_data);
+        gif->frame_count_partial = frame + 1;
+
+        /* Skip the local colour table */
+        if (flags & GIF_COLOUR_TABLE_MASK) {
+                gif_data += 3 * colour_table_size;
+                if ((gif_bytes = (gif_end - gif_data)) < 0) {
+                        return GIF_INSUFFICIENT_FRAME_DATA;
+                }
+        }
+
+        /* Ensure we have a correct code size */
+        if (gif_bytes < 1) {
+                return GIF_INSUFFICIENT_FRAME_DATA;
+        }
+        if (gif_data[0] > GIF_MAX_LZW) {
+                return GIF_DATA_ERROR;
+        }
+
+        /* Move our pointer to the actual image data */
+        gif_data++;
+        --gif_bytes;
+
+        /* Repeatedly skip blocks until we get a zero block or run out of data
+         * These blocks of image data are processed later by gif_decode_frame()
+         */
+        block_size = 0;
+        while (block_size != 1) {
+                if (gif_bytes < 1) return GIF_INSUFFICIENT_FRAME_DATA;
+                block_size = gif_data[0] + 1;
+                /* Check if the frame data runs off the end of the file	*/
+                if ((int)(gif_bytes - block_size) < 0) {
+                        /* Try to recover by signaling the end of the gif.
+                         * Once we get garbage data, there is no logical way to
+                         * determine where the next frame is.  It's probably
+                         * better to partially load the gif than not at all.
+                         */
+                        if (gif_bytes >= 2) {
+                                gif_data[0] = 0;
+                                gif_data[1] = GIF_TRAILER;
+                                gif_bytes = 1;
+                                ++gif_data;
+                                break;
+                        } else {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+                } else {
+                        gif_bytes -= block_size;
+                        gif_data += block_size;
+                }
+        }
+
+        /* Add the frame and set the display flag */
+        gif->buffer_position = gif_data - gif->gif_data;
+        gif->frame_count = frame + 1;
+        gif->frames[frame].display = true;
+
+        /* Check if we've finished */
+        if (gif_bytes < 1) {
+                return GIF_INSUFFICIENT_FRAME_DATA;
+        } else {
+                if (gif_data[0] == GIF_TRAILER) {
+                        return GIF_OK;
+                }
+        }
+        return GIF_WORKING;
 }
 
 
-/**	Updates the sprite memory size
-
-	@return GIF_INSUFFICIENT_MEMORY for a memory error
-		GIF_OK for success
-*/
-static gif_result gif_initialise_sprite(gif_animation *gif, unsigned int width, unsigned int height) {
-	unsigned int max_width;
-	unsigned int max_height;
-	struct bitmap *buffer;
-
-	/*	Check if we've changed
-	*/
-	if ((width <= gif->width) && (height <= gif->height))
-		return GIF_OK;
-
-	/*	Get our maximum values
-	*/
-	max_width = (width > gif->width) ? width : gif->width;
-	max_height = (height > gif->height) ? height : gif->height;
-
-	/*	Allocate some more memory
-	*/
-	assert(gif->bitmap_callbacks.bitmap_create);
-	if ((buffer = gif->bitmap_callbacks.bitmap_create(max_width, max_height)) == NULL)
-		return GIF_INSUFFICIENT_MEMORY;
-	assert(gif->bitmap_callbacks.bitmap_destroy);
-	gif->bitmap_callbacks.bitmap_destroy(gif->frame_image);
-	gif->frame_image = buffer;
-	gif->width = max_width;
-	gif->height = max_height;
-
-	/*	Invalidate our currently decoded image
-	*/
-	gif->decoded_frame = GIF_INVALID_FRAME;
-	return GIF_OK;
+/**
+ * Attempts to initialise the frame's extensions
+ *
+ * \param gif The animation context
+ * \param frame The frame number
+ * @return GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the
+ *         frame GIF_OK for successful initialisation.
+ */
+static gif_result
+gif_initialise_frame_extensions(gif_animation *gif, const int frame)
+{
+        unsigned char *gif_data, *gif_end;
+        int gif_bytes;
+        unsigned int block_size;
+
+        /* Get our buffer position etc.	*/
+        gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position);
+        gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size);
+
+        /* Initialise the extensions */
+        while (gif_data < gif_end && gif_data[0] == GIF_EXTENSION_INTRODUCER) {
+                ++gif_data;
+                if ((gif_bytes = (gif_end - gif_data)) < 1) {
+                        return GIF_INSUFFICIENT_FRAME_DATA;
+                }
+
+                /* Switch on extension label */
+                switch (gif_data[0]) {
+                case GIF_EXTENSION_GRAPHIC_CONTROL:
+                        /* 6-byte Graphic Control Extension is:
+                         *
+                         *	+0	CHAR	Graphic Control Label
+                         *	+1	CHAR	Block Size
+                         *	+2	CHAR	__Packed Fields__
+                         *			3BITS	Reserved
+                         *			3BITS	Disposal Method
+                         *			1BIT	User Input Flag
+                         *			1BIT	Transparent Color Flag
+                         *	+3	SHORT	Delay Time
+                         *	+5	CHAR	Transparent Color Index
+                         */
+                        if (gif_bytes < 6) {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+
+                        gif->frames[frame].frame_delay = gif_data[3] | (gif_data[4] << 8);
+                        if (gif_data[2] & GIF_TRANSPARENCY_MASK) {
+                                gif->frames[frame].transparency = true;
+                                gif->frames[frame].transparency_index = gif_data[5];
+                        }
+                        gif->frames[frame].disposal_method = ((gif_data[2] & GIF_DISPOSAL_MASK) >> 2);
+                        /* I have encountered documentation and GIFs in the
+                         * wild that use 0x04 to restore the previous frame,
+                         * rather than the officially documented 0x03.  I
+                         * believe some (older?)  software may even actually
+                         * export this way.  We handle this as a type of
+                         * "quirks" mode.
+                         */
+                        if (gif->frames[frame].disposal_method == GIF_FRAME_QUIRKS_RESTORE) {
+                                gif->frames[frame].disposal_method = GIF_FRAME_RESTORE;
+                        }
+                        gif_data += (2 + gif_data[1]);
+                        break;
+
+                case GIF_EXTENSION_APPLICATION:
+                        /* 14-byte+ Application Extension is:
+                         *
+                         *	+0    CHAR    Application Extension Label
+                         *	+1    CHAR    Block Size
+                         *	+2    8CHARS  Application Identifier
+                         *	+10   3CHARS  Appl. Authentication Code
+                         *	+13   1-256   Application Data (Data sub-blocks)
+                         */
+                        if (gif_bytes < 17) {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+                        if ((gif_data[1] == 0x0b) &&
+                            (strncmp((const char *) gif_data + 2,
+                                     "NETSCAPE2.0", 11) == 0) &&
+                            (gif_data[13] == 0x03) &&
+                            (gif_data[14] == 0x01)) {
+                                gif->loop_count = gif_data[15] | (gif_data[16] << 8);
+                        }
+                        gif_data += (2 + gif_data[1]);
+                        break;
+
+                case GIF_EXTENSION_COMMENT:
+                        /* Move the pointer to the first data sub-block Skip 1
+                         * byte for the extension label
+                         */
+                        ++gif_data;
+                        break;
+
+                default:
+                        /* Move the pointer to the first data sub-block Skip 2
+                         * bytes for the extension label and size fields Skip
+                         * the extension size itself
+                         */
+                        if (gif_bytes < 2) {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+                        gif_data += (2 + gif_data[1]);
+                }
+
+                /* Repeatedly skip blocks until we get a zero block or run out
+                 * of data This data is ignored by this gif decoder
+                 */
+                gif_bytes = (gif_end - gif_data);
+                block_size = 0;
+                while (gif_data < gif_end && gif_data[0] != GIF_BLOCK_TERMINATOR) {
+                        block_size = gif_data[0] + 1;
+                        if ((gif_bytes -= block_size) < 0) {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+                        gif_data += block_size;
+                }
+                ++gif_data;
+        }
+
+        /* Set buffer position and return */
+        gif->buffer_position = (gif_data - gif->gif_data);
+        return GIF_OK;
 }
 
 
-/**	Attempts to initialise the next frame
+/**
+ * Skips the frame's extensions (which have been previously initialised)
+ *
+ * \param gif The animation context
+ * \return GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the
+ *         frame GIF_OK for successful decoding
+ */
+static gif_result gif_skip_frame_extensions(gif_animation *gif)
+{
+        unsigned char *gif_data, *gif_end;
+        int gif_bytes;
+        unsigned int block_size;
+
+        /* Get our buffer position etc.	*/
+        gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position);
+        gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size);
+        gif_bytes = (gif_end - gif_data);
+
+        /* Skip the extensions */
+        while (gif_data < gif_end && gif_data[0] == GIF_EXTENSION_INTRODUCER) {
+                ++gif_data;
+                if (gif_data >= gif_end) {
+                        return GIF_INSUFFICIENT_FRAME_DATA;
+                }
+
+                /* Switch on extension label */
+                switch(gif_data[0]) {
+                case GIF_EXTENSION_COMMENT:
+                        /* Move the pointer to the first data sub-block
+                         * 1 byte for the extension label
+                         */
+                        ++gif_data;
+                        break;
+
+                default:
+                        /* Move the pointer to the first data sub-block 2 bytes
+                         * for the extension label and size fields Skip the
+                         * extension size itself
+                         */
+                        if (gif_data + 1 >= gif_end) {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+                        gif_data += (2 + gif_data[1]);
+                }
+
+                /* Repeatedly skip blocks until we get a zero block or run out
+                 * of data This data is ignored by this gif decoder
+                 */
+                gif_bytes = (gif_end - gif_data);
+                block_size = 0;
+                while (gif_data < gif_end && gif_data[0] != GIF_BLOCK_TERMINATOR) {
+                        block_size = gif_data[0] + 1;
+                        if ((gif_bytes -= block_size) < 0) {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+                        gif_data += block_size;
+                }
+                ++gif_data;
+        }
+
+        /* Set buffer position and return */
+        gif->buffer_position = (gif_data - gif->gif_data);
+        return GIF_OK;
+}
 
-	@return GIF_INSUFFICIENT_DATA for insufficient data to do anything
-		GIF_FRAME_DATA_ERROR for GIF frame data error
-		GIF_INSUFFICIENT_MEMORY for insufficient memory to process
-		GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
-		GIF_DATA_ERROR for GIF error (invalid frame header)
-		GIF_OK for successful decoding
-		GIF_WORKING for successful decoding if more frames are expected
-*/
-static gif_result gif_initialise_frame(gif_animation *gif) {
-	int frame;
-	gif_frame *temp_buf;
-
-	unsigned char *gif_data, *gif_end;
-	int gif_bytes;
-	unsigned int flags = 0;
-	unsigned int width, height, offset_x, offset_y;
-	unsigned int block_size, colour_table_size;
-	bool first_image = true;
-	gif_result return_value;
-
-	/*	Get the frame to decode and our data position
-	*/
-	frame = gif->frame_count;
-
-	/*	Get our buffer position etc.
-	*/
-	gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position);
-	gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size);
-	gif_bytes = (gif_end - gif_data);
-
-	/*	Check if we've finished
-	*/
-	if ((gif_bytes > 0) && (gif_data[0] == GIF_TRAILER)) return GIF_OK;
-	
-	/*	Check if we have enough data
-	 *	The shortest block of data is a 4-byte comment extension + 1-byte block terminator + 1-byte gif trailer
-	*/
-	if (gif_bytes < 6) return GIF_INSUFFICIENT_DATA;
-
-	/*	We could theoretically get some junk data that gives us millions of frames, so
-		we ensure that we don't have a silly number
-	*/
-	if (frame > 4096) return GIF_FRAME_DATA_ERROR;
-
-	/*	Get some memory to store our pointers in etc.
-	*/
-	if ((int)gif->frame_holders <= frame) {
-		/*	Allocate more memory
-		*/
-		if ((temp_buf = (gif_frame *)realloc(gif->frames,
-					(frame + 1) * sizeof(gif_frame))) == NULL)
-			return GIF_INSUFFICIENT_MEMORY;
-		gif->frames = temp_buf;
-		gif->frame_holders = frame + 1;
-	}
-
-	/*	Store our frame pointer. We would do it when allocating except we
-		start off with one frame allocated so we can always use realloc.
-	*/
-	gif->frames[frame].frame_pointer = gif->buffer_position;
-	gif->frames[frame].display = false;
-	gif->frames[frame].virgin = true;
-	gif->frames[frame].disposal_method = 0;
-	gif->frames[frame].transparency = false;
-	gif->frames[frame].frame_delay = 100;
-	gif->frames[frame].redraw_required = false;
-
-	/*	Invalidate any previous decoding we have of this frame
-	*/
-	if (gif->decoded_frame == frame)
-		gif->decoded_frame = GIF_INVALID_FRAME;
-
-	/*	We pretend to initialise the frames, but really we just skip over all
-		the data contained within. This is all basically a cut down version of
-		gif_decode_frame that doesn't have any of the LZW bits in it.
-	*/
-
-	/*	Initialise any extensions
-	*/
-	gif->buffer_position = gif_data - gif->gif_data;
-	if ((return_value = gif_initialise_frame_extensions(gif, frame)) != GIF_OK)
-		return return_value;
-	gif_data = (gif->gif_data + gif->buffer_position);
-	gif_bytes = (gif_end - gif_data);
-
-	/*	Check if we've finished
-	*/
-	if ((gif_bytes = (gif_end - gif_data)) < 1)
-		return GIF_INSUFFICIENT_FRAME_DATA;
-	else if (gif_data[0] == GIF_TRAILER) {
-		gif->buffer_position = (gif_data - gif->gif_data);
-		gif->frame_count = frame + 1;
-		return GIF_OK;
-	}
-
-	/*	If we're not done, there should be an image descriptor
-	*/
-	if (gif_data[0] != GIF_IMAGE_SEPARATOR) return GIF_FRAME_DATA_ERROR;
-
-	/*	Do some simple boundary checking
-	*/
-	if (gif_bytes < 10) return GIF_INSUFFICIENT_FRAME_DATA;
-	offset_x = gif_data[1] | (gif_data[2] << 8);
-	offset_y = gif_data[3] | (gif_data[4] << 8);
-	width = gif_data[5] | (gif_data[6] << 8);
-	height = gif_data[7] | (gif_data[8] << 8);
-
-	/*	Set up the redraw characteristics. We have to check for extending the area
-		due to multi-image frames.
-	*/
-	if (!first_image) {
-		if (gif->frames[frame].redraw_x > offset_x) {
-			gif->frames[frame].redraw_width += (gif->frames[frame].redraw_x - offset_x);
-			gif->frames[frame].redraw_x = offset_x;
-		}
-		if (gif->frames[frame].redraw_y > offset_y) {
-			gif->frames[frame].redraw_height += (gif->frames[frame].redraw_y - offset_y);
-			gif->frames[frame].redraw_y = offset_y;
-		}
-		if ((offset_x + width) > (gif->frames[frame].redraw_x + gif->frames[frame].redraw_width))
-			gif->frames[frame].redraw_width = (offset_x + width) - gif->frames[frame].redraw_x;
-		if ((offset_y + height) > (gif->frames[frame].redraw_y + gif->frames[frame].redraw_height))
-			gif->frames[frame].redraw_height = (offset_y + height) - gif->frames[frame].redraw_y;
-	} else {
-		first_image = false;
-		gif->frames[frame].redraw_x = offset_x;
-		gif->frames[frame].redraw_y = offset_y;
-		gif->frames[frame].redraw_width = width;
-		gif->frames[frame].redraw_height = height;
-	}
-
-	/*	if we are clearing the background then we need to redraw enough to cover the previous
-		frame too
-	*/
-	gif->frames[frame].redraw_required = ((gif->frames[frame].disposal_method == GIF_FRAME_CLEAR) ||
-						(gif->frames[frame].disposal_method == GIF_FRAME_RESTORE));
-
-	/*	Boundary checking - shouldn't ever happen except with junk data
-	*/
-	if (gif_initialise_sprite(gif, (offset_x + width), (offset_y + height)))
-		return GIF_INSUFFICIENT_MEMORY;
-
-	/*	Decode the flags
-	*/
-	flags = gif_data[9];
-	colour_table_size = 2 << (flags & GIF_COLOUR_TABLE_SIZE_MASK);
-
-	/*	Move our data onwards and remember we've got a bit of this frame
-	*/
-	gif_data += 10;
-	gif_bytes = (gif_end - gif_data);
-	gif->frame_count_partial = frame + 1;
-
-	/*	Skip the local colour table
-	*/
-	if (flags & GIF_COLOUR_TABLE_MASK) {
-		gif_data += 3 * colour_table_size;
-		if ((gif_bytes = (gif_end - gif_data)) < 0)
-			return GIF_INSUFFICIENT_FRAME_DATA;
-	}
-
-	/*	Ensure we have a correct code size
-	*/
-	if (gif_bytes < 1)
-		return GIF_INSUFFICIENT_FRAME_DATA;
-	if (gif_data[0] > GIF_MAX_LZW)
-		return GIF_DATA_ERROR;
-
-	/*	Move our pointer to the actual image data
-	*/
-	gif_data++;
-	--gif_bytes;
-
-	/*	Repeatedly skip blocks until we get a zero block or run out of data
-	 *	These blocks of image data are processed later by gif_decode_frame()
-	*/
-	block_size = 0;
-	while (block_size != 1) {
-		if (gif_bytes < 1) return GIF_INSUFFICIENT_FRAME_DATA;
-		block_size = gif_data[0] + 1;
-		/*	Check if the frame data runs off the end of the file
-		*/
-		if ((int)(gif_bytes - block_size) < 0) {
-			/*	Try to recover by signaling the end of the gif.
-			 *	Once we get garbage data, there is no logical
-			 *	way to determine where the next frame is.
-			 *	It's probably better to partially load the gif
-			 *	than not at all.
-			*/
-			if (gif_bytes >= 2) {
-				gif_data[0] = 0;
-				gif_data[1] = GIF_TRAILER;
-				gif_bytes = 1;
-				++gif_data;
-				break;
-			} else
-				return GIF_INSUFFICIENT_FRAME_DATA;
-		} else {
-			gif_bytes -= block_size;
-			gif_data += block_size;
-		}
-	}
-
-	/*	Add the frame and set the display flag
-	*/
-	gif->buffer_position = gif_data - gif->gif_data;
-	gif->frame_count = frame + 1;
-	gif->frames[frame].display = true;
-
-	/*	Check if we've finished
-	*/
-	if (gif_bytes < 1)
-		return GIF_INSUFFICIENT_FRAME_DATA;
-	else
-		if (gif_data[0] == GIF_TRAILER) return GIF_OK;
-	return GIF_WORKING;
+static unsigned int gif_interlaced_line(int height, int y) {
+        if ((y << 3) < height) {
+                return (y << 3);
+        }
+        y -= ((height + 7) >> 3);
+        if ((y << 3) < (height - 4)) {
+                return (y << 3) + 4;
+        }
+        y -= ((height + 3) >> 3);
+        if ((y << 2) < (height - 2)) {
+                return (y << 2) + 2;
+        }
+        y -= ((height + 1) >> 2);
+        return (y << 1) + 1;
 }
 
-/**	Attempts to initialise the frame's extensions
 
-	@return GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
-		GIF_OK for successful initialisation
-*/
-static gif_result gif_initialise_frame_extensions(gif_animation *gif, const int frame) {
-	unsigned char *gif_data, *gif_end;
-	int gif_bytes;
-	unsigned int block_size;
-
-	/*	Get our buffer position etc.
-	*/
-	gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position);
-	gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size);
-	
-	/*	Initialise the extensions
-	*/
-	while (gif_data < gif_end && gif_data[0] == GIF_EXTENSION_INTRODUCER) {
-		++gif_data;
-		if ((gif_bytes = (gif_end - gif_data)) < 1)
-			return GIF_INSUFFICIENT_FRAME_DATA;
-
-		/*	Switch on extension label
-		*/
-		switch(gif_data[0]) {
-			/* 6-byte Graphic Control Extension is:
-			 *
-			 *	+0	CHAR	Graphic Control Label
-			 *	+1	CHAR	Block Size
-			 *	+2	CHAR	__Packed Fields__
-			 *			3BITS	Reserved
-			 *			3BITS	Disposal Method
-			 *			1BIT	User Input Flag
-			 *			1BIT	Transparent Color Flag
-			 *	+3	SHORT	Delay Time
-			 *	+5	CHAR	Transparent Color Index
-			*/
-			case GIF_EXTENSION_GRAPHIC_CONTROL:
-				if (gif_bytes < 6) return GIF_INSUFFICIENT_FRAME_DATA;
-				gif->frames[frame].frame_delay = gif_data[3] | (gif_data[4] << 8);
-				if (gif_data[2] & GIF_TRANSPARENCY_MASK) {
-					gif->frames[frame].transparency = true;
-					gif->frames[frame].transparency_index = gif_data[5];
-				}
-				gif->frames[frame].disposal_method = ((gif_data[2] & GIF_DISPOSAL_MASK) >> 2);
-				/*	I have encountered documentation and GIFs in the wild that use
-				 *	0x04 to restore the previous frame, rather than the officially
-				 *	documented 0x03.  I believe some (older?) software may even actually
-				 *	export this way.  We handle this as a type of "quirks" mode.
-				*/
-				if (gif->frames[frame].disposal_method == GIF_FRAME_QUIRKS_RESTORE)
-					gif->frames[frame].disposal_method = GIF_FRAME_RESTORE;
-				gif_data += (2 + gif_data[1]);
-				break;
-
-			/* 14-byte+ Application Extension is:
-			 *
-			 *	+0	CHAR	Application Extension Label
-			 *	+1	CHAR	Block Size
-			 *	+2	8CHARS	Application Identifier
-			 *	+10	3CHARS	Appl. Authentication Code
-			 *	+13	1-256	Application Data (Data sub-blocks)
-			*/
-			case GIF_EXTENSION_APPLICATION:
-				if (gif_bytes < 17) return GIF_INSUFFICIENT_FRAME_DATA;
-				if ((gif_data[1] == 0x0b) &&
-					(strncmp((const char *) gif_data + 2,
-						"NETSCAPE2.0", 11) == 0) &&
-					(gif_data[13] == 0x03) &&
-					(gif_data[14] == 0x01)) {
-						gif->loop_count = gif_data[15] | (gif_data[16] << 8);
-				}
-				gif_data += (2 + gif_data[1]);
-				break;
-
-			/*	Move the pointer to the first data sub-block
-			 *	Skip 1 byte for the extension label
-			*/
-			case GIF_EXTENSION_COMMENT:
-				++gif_data;
-				break;
-
-			/*	Move the pointer to the first data sub-block
-			 *	Skip 2 bytes for the extension label and size fields
-			 *	Skip the extension size itself
-			*/
-			default:
-				if (gif_bytes < 2) return GIF_INSUFFICIENT_FRAME_DATA;
-				gif_data += (2 + gif_data[1]);
-		}
-
-		/*	Repeatedly skip blocks until we get a zero block or run out of data
-		 *	This data is ignored by this gif decoder
-		*/
-		gif_bytes = (gif_end - gif_data);
-		block_size = 0;
-		while (gif_data < gif_end && gif_data[0] != GIF_BLOCK_TERMINATOR) {
-			block_size = gif_data[0] + 1;
-			if ((gif_bytes -= block_size) < 0)
-				return GIF_INSUFFICIENT_FRAME_DATA;
-			gif_data += block_size;
-		}
-		++gif_data;
-	}
-
-	/*	Set buffer position and return
-	*/
-	gif->buffer_position = (gif_data - gif->gif_data);
-	return GIF_OK;
+/**
+ * Initialise LZW decoding
+ */
+void gif_init_LZW(gif_animation *gif)
+{
+        int i;
+
+        gif->current_error = 0;
+        if (clear_code >= (1 << GIF_MAX_LZW)) {
+                stack_pointer = stack;
+                gif->current_error = GIF_FRAME_DATA_ERROR;
+                return;
+        }
+
+        /* initialise our table */
+        memset(table, 0x00, (1 << GIF_MAX_LZW) * 8);
+        for (i = 0; i < clear_code; ++i) {
+                table[1][i] = i;
+        }
+
+        /* update our LZW parameters */
+        code_size = set_code_size + 1;
+        max_code_size = clear_code << 1;
+        max_code = clear_code + 2;
+        stack_pointer = stack;
+        do {
+                firstcode = oldcode = gif_next_code(gif, code_size);
+        } while (firstcode == clear_code);
+        *stack_pointer++ =firstcode;
 }
 
 
-/**	Decodes a GIF frame.
+static bool gif_next_LZW(gif_animation *gif)
+{
+        int code, incode;
+        int block_size;
+        int new_code;
+
+        code = gif_next_code(gif, code_size);
+        if (code < 0) {
+                gif->current_error = code;
+                return false;
+        } else if (code == clear_code) {
+                gif_init_LZW(gif);
+                return true;
+        } else if (code == end_code) {
+                /* skip to the end of our data so multi-image GIFs work */
+                if (zero_data_block) {
+                        gif->current_error = GIF_FRAME_DATA_ERROR;
+                        return false;
+                }
+                block_size = 0;
+                while (block_size != 1 &&
+                       gif->buffer_position < gif->buffer_size) {
+                        block_size = gif->gif_data[gif->buffer_position] + 1;
+                        gif->buffer_position += block_size;
+                }
+                gif->current_error = GIF_FRAME_DATA_ERROR;
+                return false;
+        }
+
+        incode = code;
+        if (code >= max_code) {
+                if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2)) {
+                        gif->current_error = GIF_FRAME_DATA_ERROR;
+                        return false;
+                }
+                *stack_pointer++ = firstcode;
+                code = oldcode;
+        }
+
+        /* The following loop is the most important in the GIF decoding cycle
+         * as every single pixel passes through it.
+         *
+         * Note: our stack is always big enough to hold a complete decompressed
+         * chunk.
+         */
+        while (code >= clear_code) {
+                if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2) ||
+                    code >= (1 << GIF_MAX_LZW)) {
+                        gif->current_error = GIF_FRAME_DATA_ERROR;
+                        return false;
+                }
+                *stack_pointer++ = table[1][code];
+                new_code = table[0][code];
+                if (new_code < clear_code) {
+                        code = new_code;
+                        break;
+                }
+
+                if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2) ||
+                    new_code >= (1 << GIF_MAX_LZW)) {
+                        gif->current_error = GIF_FRAME_DATA_ERROR;
+                        return false;
+                }
+                *stack_pointer++ = table[1][new_code];
+                code = table[0][new_code];
+                if (code == new_code) {
+                        gif->current_error = GIF_FRAME_DATA_ERROR;
+                        return false;
+                }
+        }
+
+        if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2)) {
+                gif->current_error = GIF_FRAME_DATA_ERROR;
+                return false;
+        }
+        *stack_pointer++ = firstcode = table[1][code];
+
+        if ((code = max_code) < (1 << GIF_MAX_LZW)) {
+                table[0][code] = oldcode;
+                table[1][code] = firstcode;
+                ++max_code;
+                if ((max_code >= max_code_size) &&
+                    (max_code_size < (1 << GIF_MAX_LZW))) {
+                        max_code_size = max_code_size << 1;
+                        ++code_size;
+                }
+        }
+        oldcode = incode;
+        return true;
+}
 
-	@return GIF_FRAME_DATA_ERROR for GIF frame data error
-		GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
-		GIF_DATA_ERROR for GIF error (invalid frame header)
-		GIF_INSUFFICIENT_DATA for insufficient data to do anything
-		GIF_INSUFFICIENT_MEMORY for insufficient memory to process
-		GIF_OK for successful decoding
-		If a frame does not contain any image data, GIF_OK is returned and
-			gif->current_error is set to GIF_FRAME_NO_DISPLAY
-*/
-gif_result gif_decode_frame(gif_animation *gif, unsigned int frame) {
-	unsigned int index = 0;
-	unsigned char *gif_data, *gif_end;
-	int gif_bytes;
-	unsigned int width, height, offset_x, offset_y;
-	unsigned int flags, colour_table_size, interlace;
-	unsigned int *colour_table;
-	unsigned int *frame_data = 0;	// Set to 0 for no warnings
-	unsigned int *frame_scanline;
-	unsigned int save_buffer_position;
-	unsigned int return_value = 0;
-	unsigned int x, y, decode_y, burst_bytes;
-	int last_undisposed_frame = (frame - 1);
-	register unsigned char colour;
-
-	/*	Ensure this frame is supposed to be decoded
-	*/
-	if (gif->frames[frame].display == false) {
-		gif->current_error = GIF_FRAME_NO_DISPLAY;
-		return GIF_OK;
-	}
-
-	/*	Ensure we have a frame to decode
-	*/
-	if (frame > gif->frame_count_partial)
-		return GIF_INSUFFICIENT_DATA;
-	if ((!clear_image) && ((int)frame == gif->decoded_frame))
-		return GIF_OK;
-
-	/*	Get the start of our frame data and the end of the GIF data
-	*/
-	gif_data = gif->gif_data + gif->frames[frame].frame_pointer;
-	gif_end = gif->gif_data + gif->buffer_size;
-	gif_bytes = (gif_end - gif_data);
-
-	/*	Check if we have enough data
-	 *	The shortest block of data is a 10-byte image descriptor + 1-byte gif trailer
-	*/
-	if (gif_bytes < 12) return GIF_INSUFFICIENT_FRAME_DATA;
-
-	/*	Save the buffer position
-	*/
-	save_buffer_position = gif->buffer_position;
-	gif->buffer_position = gif_data - gif->gif_data;
-
-	/*	Skip any extensions because we all ready processed them
-	*/
-	if ((return_value = gif_skip_frame_extensions(gif)) != GIF_OK)
-		goto gif_decode_frame_exit;
-	gif_data = (gif->gif_data + gif->buffer_position);
-	gif_bytes = (gif_end - gif_data);
-
-	/*	Ensure we have enough data for the 10-byte image descriptor + 1-byte gif trailer
-	*/
-	if (gif_bytes < 12) {
-		return_value = GIF_INSUFFICIENT_FRAME_DATA;
-		goto gif_decode_frame_exit;
-	}
-
-	/* 10-byte Image Descriptor is:
-	 *
-	 *	+0	CHAR	Image Separator (0x2c)
-	 *	+1	SHORT	Image Left Position
-	 *	+3	SHORT	Image Top Position
-	 *	+5	SHORT	Width
-	 *	+7	SHORT	Height
-	 *	+9	CHAR	__Packed Fields__
-	 *			1BIT	Local Colour Table Flag
-	 *			1BIT	Interlace Flag
-	 *			1BIT	Sort Flag
-	 *			2BITS	Reserved
-	 *			3BITS	Size of Local Colour Table
-	*/
-	if (gif_data[0] != GIF_IMAGE_SEPARATOR) {
-		return_value = GIF_DATA_ERROR;
-		goto gif_decode_frame_exit;
-	}
-	offset_x = gif_data[1] | (gif_data[2] << 8);
-	offset_y = gif_data[3] | (gif_data[4] << 8);
-	width = gif_data[5] | (gif_data[6] << 8);
-	height = gif_data[7] | (gif_data[8] << 8);
-
-	/*	Boundary checking - shouldn't ever happen except unless the data has been
-		modified since initialisation.
-	*/
-	if ((offset_x + width > gif->width) || (offset_y + height > gif->height)) {
-		return_value = GIF_DATA_ERROR;
-		goto gif_decode_frame_exit;
-	}
-
-	/*	Decode the flags
-	*/
-	flags = gif_data[9];
-	colour_table_size = 2 << (flags & GIF_COLOUR_TABLE_SIZE_MASK);
-	interlace = flags & GIF_INTERLACE_MASK;
-
-	/*	Move our pointer to the colour table or image data (if no colour table is given)
-	*/
-	gif_data += 10;
-	gif_bytes = (gif_end - gif_data);
-
-	/*	Set up the colour table
-	*/
-	if (flags & GIF_COLOUR_TABLE_MASK) {
-		if (gif_bytes < (int)(3 * colour_table_size)) {
-			return_value = GIF_INSUFFICIENT_FRAME_DATA;
-			goto gif_decode_frame_exit;
-		}
-		colour_table = gif->local_colour_table;
-		if (!clear_image) {
-			for (index = 0; index < colour_table_size; index++) {
-				/* Gif colour map contents are r,g,b.
-				 *
-				 * We want to pack them bytewise into the 
-				 * colour table, such that the red component
-				 * is in byte 0 and the alpha component is in
-				 * byte 3.
-				 */
-				unsigned char *entry = 
-					(unsigned char *) &colour_table[index];
-
-				entry[0] = gif_data[0];	/* r */
-				entry[1] = gif_data[1];	/* g */
-				entry[2] = gif_data[2];	/* b */
-				entry[3] = 0xff;	/* a */
-
-				gif_data += 3;
-			}
-		} else {
-			gif_data += 3 * colour_table_size;
-		}
-		gif_bytes = (gif_end - gif_data);
-	} else {
-		colour_table = gif->global_colour_table;
-	}
-
-	/*	Check if we've finished
-	*/
-	if (gif_bytes < 1) {
-		return_value = GIF_INSUFFICIENT_FRAME_DATA;
-		goto gif_decode_frame_exit;
-	} else if (gif_data[0] == GIF_TRAILER) {
-		return_value = GIF_OK;
-		goto gif_decode_frame_exit;
-	}
-
-	/*	Get the frame data
-	*/
-	assert(gif->bitmap_callbacks.bitmap_get_buffer);
-	frame_data = (void *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
-	if (!frame_data)
-		return GIF_INSUFFICIENT_MEMORY;
-
-	/*	If we are clearing the image we just clear, if not decode
-	*/
-	if (!clear_image) {
-		/*	Ensure we have enough data for a 1-byte LZW code size + 1-byte gif trailer
-		*/
-		if (gif_bytes < 2) {
-			return_value = GIF_INSUFFICIENT_FRAME_DATA;
-			goto gif_decode_frame_exit;
-		/*	If we only have a 1-byte LZW code size + 1-byte gif trailer, we're finished
-		*/
-		} else if ((gif_bytes == 2) && (gif_data[1] == GIF_TRAILER)) {
-			return_value = GIF_OK;
-			goto gif_decode_frame_exit;
-		}
-
-		/*	If the previous frame's disposal method requires we restore the background
-		 *	colour or this is the first frame, clear the frame data
-		*/
-		if ((frame == 0) || (gif->decoded_frame == GIF_INVALID_FRAME)) {
-			memset((char*)frame_data, GIF_TRANSPARENT_COLOUR, gif->width * gif->height * sizeof(int));
-			gif->decoded_frame = frame;
-			/* The line below would fill the image with its background color, but because GIFs support
-			 * transparency we likely wouldn't want to do that. */
-			/* memset((char*)frame_data, colour_table[gif->background_index], gif->width * gif->height * sizeof(int)); */
-		} else if ((frame != 0) && (gif->frames[frame - 1].disposal_method == GIF_FRAME_CLEAR)) {
-			clear_image = true;
-			if ((return_value = gif_decode_frame(gif, (frame - 1))) != GIF_OK)
-				goto gif_decode_frame_exit;
-			clear_image = false;
-		/*	If the previous frame's disposal method requires we restore the previous
-		 *	image, find the last image set to "do not dispose" and get that frame data
-		*/
-		} else if ((frame != 0) && (gif->frames[frame - 1].disposal_method == GIF_FRAME_RESTORE)) {
-			while ((last_undisposed_frame != -1) && (gif->frames[--last_undisposed_frame].disposal_method == GIF_FRAME_RESTORE))
-				;
-
-			/*	If we don't find one, clear the frame data
-			 */
-			if (last_undisposed_frame == -1) {
-				/* see notes above on transparency vs. background color */
-				memset((char*)frame_data, GIF_TRANSPARENT_COLOUR, gif->width * gif->height * sizeof(int));
-			} else {
-				if ((return_value = gif_decode_frame(gif, last_undisposed_frame)) != GIF_OK)
-					goto gif_decode_frame_exit;
-				/*	Get this frame's data
-				*/
-				assert(gif->bitmap_callbacks.bitmap_get_buffer);
-				frame_data = (void *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
-				if (!frame_data)
-					return GIF_INSUFFICIENT_MEMORY;
-			}
-		}
-		gif->decoded_frame = frame;
-
-		/*	Initialise the LZW decoding
-		*/
-		set_code_size = gif_data[0];
-		gif->buffer_position = (gif_data - gif->gif_data) + 1;
-
-		/*	Set our code variables
-		*/
-		code_size = set_code_size + 1;
-		clear_code = (1 << set_code_size);
-		end_code = clear_code + 1;
-		max_code_size = clear_code << 1;
-		max_code = clear_code + 2;
-		curbit = lastbit = 0;
-		last_byte = 2;
-		get_done = false;
-		direct = buf;
-		gif_init_LZW(gif);
-
-		/*	Decompress the data
-		*/
-		for (y = 0; y < height; y++) {
-			if (interlace)
-				decode_y = gif_interlaced_line(height, y) + offset_y;
-			else
-				decode_y = y + offset_y;
-			frame_scanline = frame_data + offset_x + (decode_y * gif->width);
-
-			/*	Rather than decoding pixel by pixel, we try to burst out streams
-				of data to remove the need for end-of data checks every pixel.
-			*/
-			x = width;
-			while (x > 0) {
-				burst_bytes = (stack_pointer - stack);
-				if (burst_bytes > 0) {
-					if (burst_bytes > x)
-						burst_bytes = x;
-					x -= burst_bytes;
-					while (burst_bytes-- > 0) {
-						colour = *--stack_pointer;
-						if (((gif->frames[frame].transparency) &&
-							(colour != gif->frames[frame].transparency_index)) ||
-							(!gif->frames[frame].transparency))
-								*frame_scanline = colour_table[colour];
-						frame_scanline++;
-					}
-				} else {
-					if (!gif_next_LZW(gif)) {
-						/*	Unexpected end of frame, try to recover
-						*/
-						if (gif->current_error == GIF_END_OF_FRAME)
-							return_value = GIF_OK;
-						else
-							return_value = gif->current_error;
-						goto gif_decode_frame_exit;
-					}
-				}
-			}
-		}
-	} else {
-		/*	Clear our frame
-		*/
-		if (gif->frames[frame].disposal_method == GIF_FRAME_CLEAR) {
-			for (y = 0; y < height; y++) {
-				frame_scanline = frame_data + offset_x + ((offset_y + y) * gif->width);
-				if (gif->frames[frame].transparency)
-					memset(frame_scanline, GIF_TRANSPARENT_COLOUR, width * 4);
-				else
-					memset(frame_scanline, colour_table[gif->background_index], width * 4);
-			}
-		}
-	}
-gif_decode_frame_exit:
+static int gif_next_code(gif_animation *gif, int code_size)
+{
+        int i, j, end, count, ret;
+        unsigned char *b;
+
+        end = curbit + code_size;
+        if (end >= lastbit) {
+                if (get_done) {
+                        return GIF_END_OF_FRAME;
+                }
+                buf[0] = direct[last_byte - 2];
+                buf[1] = direct[last_byte - 1];
+
+                /* get the next block */
+                direct = gif->gif_data + gif->buffer_position;
+                if (gif->buffer_position >= gif->buffer_size) {
+                        return GIF_INSUFFICIENT_FRAME_DATA;
+                }
+                zero_data_block = ((count = direct[0]) == 0);
+                if ((gif->buffer_position + count) >= gif->buffer_size) {
+                        return GIF_INSUFFICIENT_FRAME_DATA;
+                }
+                if (count == 0) {
+                        get_done = true;
+                } else {
+                        if (gif->buffer_position + 3 >= gif->buffer_size) {
+                                return GIF_INSUFFICIENT_FRAME_DATA;
+                        }
+                        direct -= 1;
+                        buf[2] = direct[2];
+                        buf[3] = direct[3];
+                }
+                gif->buffer_position += count + 1;
+
+                /* update our variables */
+                last_byte = 2 + count;
+                curbit = (curbit - lastbit) + 16;
+                lastbit = (2 + count) << 3;
+                end = curbit + code_size;
+        }
+
+        i = curbit >> 3;
+        if (i < 2) {
+                b = buf;
+        } else {
+                b = direct;
+        }
+
+        ret = b[i];
+        j = (end >> 3) - 1;
+        if (i <= j) {
+                ret |= (b[i + 1] << 8);
+                if (i < j) {
+                        ret |= (b[i + 2] << 16);
+                }
+        }
+        ret = (ret >> (curbit % 8)) & maskTbl[code_size];
+        curbit += code_size;
+        return ret;
+}
 
-	/*	Check if we should test for optimisation
-	*/
-	if (gif->frames[frame].virgin) {
-		if (gif->bitmap_callbacks.bitmap_test_opaque)
-			gif->frames[frame].opaque = gif->bitmap_callbacks.bitmap_test_opaque(gif->frame_image);
-		else
-			gif->frames[frame].opaque = false;
-		gif->frames[frame].virgin = false;
-	}
-	if (gif->bitmap_callbacks.bitmap_set_opaque)
-		gif->bitmap_callbacks.bitmap_set_opaque(gif->frame_image, gif->frames[frame].opaque);
-	if (gif->bitmap_callbacks.bitmap_modified)
-		gif->bitmap_callbacks.bitmap_modified(gif->frame_image);
-
-	/*	Restore the buffer position
-	*/
-	gif->buffer_position = save_buffer_position;
-
-	/*	Success!
-	*/
-	return return_value;
 
+/* exported function documented in libnsgif.h */
+void gif_create(gif_animation *gif, gif_bitmap_callback_vt *bitmap_callbacks)
+{
+        memset(gif, 0, sizeof(gif_animation));
+        gif->bitmap_callbacks = *bitmap_callbacks;
+        gif->decoded_frame = GIF_INVALID_FRAME;
 }
 
-/**	Skips the frame's extensions (which have been previously initialised)
 
-	@return GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
-		GIF_OK for successful decoding
-*/
-static gif_result gif_skip_frame_extensions(gif_animation *gif) {
-	unsigned char *gif_data, *gif_end;
-	int gif_bytes;
-	unsigned int block_size;
-
-	/*	Get our buffer position etc.
-	*/
-	gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position);
-	gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size);
-	gif_bytes = (gif_end - gif_data);
-
-	/*	Skip the extensions
-	*/
-	while (gif_data < gif_end && gif_data[0] == GIF_EXTENSION_INTRODUCER) {
-		++gif_data;
-		if (gif_data >= gif_end)
-			return GIF_INSUFFICIENT_FRAME_DATA;
-
-		/*	Switch on extension label
-		*/
-		switch(gif_data[0]) {
-			/*	Move the pointer to the first data sub-block
-			 *	1 byte for the extension label
-			*/
-			case GIF_EXTENSION_COMMENT:
-				++gif_data;
-				break;
-
-			/*	Move the pointer to the first data sub-block
-			 *	2 bytes for the extension label and size fields
-			 *	Skip the extension size itself
-			*/
-			default:
-				if (gif_data + 1 >= gif_end)
-					return GIF_INSUFFICIENT_FRAME_DATA;
-				gif_data += (2 + gif_data[1]);
-		}
-
-		/*	Repeatedly skip blocks until we get a zero block or run out of data
-		 *	This data is ignored by this gif decoder
-		*/
-		gif_bytes = (gif_end - gif_data);
-		block_size = 0;
-		while (gif_data < gif_end && gif_data[0] != GIF_BLOCK_TERMINATOR) {
-			block_size = gif_data[0] + 1;
-			if ((gif_bytes -= block_size) < 0)
-				return GIF_INSUFFICIENT_FRAME_DATA;
-			gif_data += block_size;
-		}
-		++gif_data;
-	}
-
-	/*	Set buffer position and return
-	*/
-	gif->buffer_position = (gif_data - gif->gif_data);
-	return GIF_OK;
+/* exported function documented in libnsgif.h */
+gif_result gif_initialise(gif_animation *gif, size_t size, unsigned char *data)
+{
+        unsigned char *gif_data;
+        unsigned int index;
+        gif_result return_value;
+
+        /* Initialize values */
+        gif->buffer_size = size;
+        gif->gif_data = data;
+
+        /* Check for sufficient data to be a GIF (6-byte header + 7-byte
+         * logical screen descriptor)
+         */
+        if (gif->buffer_size < 13) {
+                return GIF_INSUFFICIENT_DATA;
+        }
+
+        /* Get our current processing position */
+        gif_data = gif->gif_data + gif->buffer_position;
+
+        /* See if we should initialise the GIF */
+        if (gif->buffer_position == 0) {
+                /* We want everything to be NULL before we start so we've no
+                 * chance of freeing bad pointers (paranoia)
+                 */
+                gif->frame_image = NULL;
+                gif->frames = NULL;
+                gif->local_colour_table = NULL;
+                gif->global_colour_table = NULL;
+
+                /* The caller may have been lazy and not reset any values */
+                gif->frame_count = 0;
+                gif->frame_count_partial = 0;
+                gif->decoded_frame = GIF_INVALID_FRAME;
+
+                /* 6-byte GIF file header is:
+                 *
+                 *	+0	3CHARS	Signature ('GIF')
+                 *	+3	3CHARS	Version ('87a' or '89a')
+                 */
+                if (strncmp((const char *) gif_data, "GIF", 3) != 0) {
+                        return GIF_DATA_ERROR;
+                }
+                gif_data += 3;
+
+                /* Ensure GIF reports version 87a or 89a */
+                /*
+                if ((strncmp(gif_data, "87a", 3) != 0) &&
+                    (strncmp(gif_data, "89a", 3) != 0))
+                               LOG(("Unknown GIF format - proceeding anyway"));
+                */
+                gif_data += 3;
+
+                /* 7-byte Logical Screen Descriptor is:
+                 *
+                 *	+0	SHORT	Logical Screen Width
+                 *	+2	SHORT	Logical Screen Height
+                 *	+4	CHAR	__Packed Fields__
+                 *                      1BIT	Global Colour Table Flag
+                 *                      3BITS	Colour Resolution
+                 *                      1BIT	Sort Flag
+                 *                      3BITS	Size of Global Colour Table
+                 *	+5	CHAR	Background Colour Index
+                 *	+6	CHAR	Pixel Aspect Ratio
+                 */
+                gif->width = gif_data[0] | (gif_data[1] << 8);
+                gif->height = gif_data[2] | (gif_data[3] << 8);
+                gif->global_colours = (gif_data[4] & GIF_COLOUR_TABLE_MASK);
+                gif->colour_table_size = (2 << (gif_data[4] & GIF_COLOUR_TABLE_SIZE_MASK));
+                gif->background_index = gif_data[5];
+                gif->aspect_ratio = gif_data[6];
+                gif->loop_count = 1;
+                gif_data += 7;
+
+                /* Some broken GIFs report the size as the screen size they
+                 * were created in. As such, we detect for the common cases and
+                 * set the sizes as 0 if they are found which results in the
+                 * GIF being the maximum size of the frames.
+                 */
+                if (((gif->width == 640) && (gif->height == 480)) ||
+                    ((gif->width == 640) && (gif->height == 512)) ||
+                    ((gif->width == 800) && (gif->height == 600)) ||
+                    ((gif->width == 1024) && (gif->height == 768)) ||
+                    ((gif->width == 1280) && (gif->height == 1024)) ||
+                    ((gif->width == 1600) && (gif->height == 1200)) ||
+                    ((gif->width == 0) || (gif->height == 0)) ||
+                    ((gif->width > 2048) || (gif->height > 2048))) {
+                        gif->width = 1;
+                        gif->height = 1;
+                }
+
+                /* Allocate some data irrespective of whether we've got any
+                 * colour tables. We always get the maximum size in case a GIF
+                 * is lying to us. It's far better to give the wrong colours
+                 * than to trample over some memory somewhere.
+                */
+                gif->global_colour_table = calloc(GIF_MAX_COLOURS, sizeof(unsigned int));
+                gif->local_colour_table = calloc(GIF_MAX_COLOURS, sizeof(unsigned int));
+                if ((gif->global_colour_table == NULL) ||
+                    (gif->local_colour_table == NULL)) {
+                        gif_finalise(gif);
+                        return GIF_INSUFFICIENT_MEMORY;
+                }
+
+                /* Set the first colour to a value that will never occur in
+                 * reality so we know if we've processed it
+                */
+                gif->global_colour_table[0] = GIF_PROCESS_COLOURS;
+
+                /* Check if the GIF has no frame data (13-byte header + 1-byte
+                 * termination block) Although generally useless, the GIF
+                 * specification does not expressly prohibit this
+                 */
+                if (gif->buffer_size == 14) {
+                        if (gif_data[0] == GIF_TRAILER) {
+                                return GIF_OK;
+                        } else {
+                                return GIF_INSUFFICIENT_DATA;
+                        }
+                }
+
+                /* Initialise enough workspace for 4 frames initially */
+                if ((gif->frames = (gif_frame *)malloc(sizeof(gif_frame))) == NULL) {
+                        gif_finalise(gif);
+                        return GIF_INSUFFICIENT_MEMORY;
+                }
+                gif->frame_holders = 1;
+
+                /* Initialise the bitmap header */
+                assert(gif->bitmap_callbacks.bitmap_create);
+                gif->frame_image = gif->bitmap_callbacks.bitmap_create(gif->width, gif->height);
+                if (gif->frame_image == NULL) {
+                        gif_finalise(gif);
+                        return GIF_INSUFFICIENT_MEMORY;
+                }
+
+                /* Remember we've done this now */
+                gif->buffer_position = gif_data - gif->gif_data;
+        }
+
+        /*  Do the colour map if we haven't already. As the top byte is always
+         *  0xff or 0x00 depending on the transparency we know if it's been
+         *  filled in.
+         */
+        if (gif->global_colour_table[0] == GIF_PROCESS_COLOURS) {
+                /* Check for a global colour map signified by bit 7 */
+                if (gif->global_colours) {
+                        if (gif->buffer_size < (gif->colour_table_size * 3 + 12)) {
+                                return GIF_INSUFFICIENT_DATA;
+                        }
+                        for (index = 0; index < gif->colour_table_size; index++) {
+                                /* Gif colour map contents are r,g,b.
+                                 *
+                                 * We want to pack them bytewise into the
+                                 * colour table, such that the red component
+                                 * is in byte 0 and the alpha component is in
+                                 * byte 3.
+                                 */
+                                unsigned char *entry = (unsigned char *) &gif->
+                                                       global_colour_table[index];
+
+                                entry[0] = gif_data[0];	/* r */
+                                entry[1] = gif_data[1];	/* g */
+                                entry[2] = gif_data[2];	/* b */
+                                entry[3] = 0xff;	/* a */
+
+                                gif_data += 3;
+                        }
+                        gif->buffer_position = (gif_data - gif->gif_data);
+                } else {
+                        /* Create a default colour table with the first two
+                         * colours as black and white
+                         */
+                        unsigned int *entry = gif->global_colour_table;
+
+                        entry[0] = 0x00000000;
+                        /* Force Alpha channel to opaque */
+                        ((unsigned char *) entry)[3] = 0xff;
+
+                        entry[1] = 0xffffffff;
+                }
+        }
+
+        /* Repeatedly try to initialise frames */
+        while ((return_value = gif_initialise_frame(gif)) == GIF_WORKING);
+
+        /* If there was a memory error tell the caller */
+        if ((return_value == GIF_INSUFFICIENT_MEMORY) ||
+            (return_value == GIF_DATA_ERROR)) {
+                return return_value;
+        }
+
+        /* If we didn't have some frames then a GIF_INSUFFICIENT_DATA becomes a
+         * GIF_INSUFFICIENT_FRAME_DATA
+         */
+        if ((return_value == GIF_INSUFFICIENT_DATA) &&
+            (gif->frame_count_partial > 0)) {
+                return GIF_INSUFFICIENT_FRAME_DATA;
+        }
+
+        /* Return how many we got */
+        return return_value;
 }
 
-static unsigned int gif_interlaced_line(int height, int y) {
-	if ((y << 3) < height) return (y << 3);
-	y -= ((height + 7) >> 3);
-	if ((y << 3) < (height - 4)) return (y << 3) + 4;
-	y -= ((height + 3) >> 3);
-	if ((y << 2) < (height - 2)) return (y << 2) + 2;
-	y -= ((height + 1) >> 2);
-	return (y << 1) + 1;
-}
 
-/*	Releases any workspace held by the animation
-*/
-void gif_finalise(gif_animation *gif) {
-	/*	Release all our memory blocks
-	*/
-	if (gif->frame_image) {
-		assert(gif->bitmap_callbacks.bitmap_destroy);
-		gif->bitmap_callbacks.bitmap_destroy(gif->frame_image);
-	}
-	gif->frame_image = NULL;
-	free(gif->frames);
-	gif->frames = NULL;
-	free(gif->local_colour_table);
-	gif->local_colour_table = NULL;
-	free(gif->global_colour_table);
-	gif->global_colour_table = NULL;
-}
+/* exported function documented in libnsgif.h */
+gif_result gif_decode_frame(gif_animation *gif, unsigned int frame)
+{
+        unsigned int index = 0;
+        unsigned char *gif_data, *gif_end;
+        int gif_bytes;
+        unsigned int width, height, offset_x, offset_y;
+        unsigned int flags, colour_table_size, interlace;
+        unsigned int *colour_table;
+        unsigned int *frame_data = 0;	// Set to 0 for no warnings
+        unsigned int *frame_scanline;
+        unsigned int save_buffer_position;
+        unsigned int return_value = 0;
+        unsigned int x, y, decode_y, burst_bytes;
+        int last_undisposed_frame = (frame - 1);
+        register unsigned char colour;
+
+        /* Ensure this frame is supposed to be decoded */
+        if (gif->frames[frame].display == false) {
+                gif->current_error = GIF_FRAME_NO_DISPLAY;
+                return GIF_OK;
+        }
+
+        /* Ensure the frame is in range to decode */
+        if (frame > gif->frame_count_partial) {
+                return GIF_INSUFFICIENT_DATA;
+        }
+
+        /* done if frame is already decoded */
+        if ((!clear_image) &&
+            ((int)frame == gif->decoded_frame)) {
+                return GIF_OK;
+        }
+
+        /* Get the start of our frame data and the end of the GIF data */
+        gif_data = gif->gif_data + gif->frames[frame].frame_pointer;
+        gif_end = gif->gif_data + gif->buffer_size;
+        gif_bytes = (gif_end - gif_data);
+
+        /*
+         * Ensure there is a minimal amount of data to proceed.  The shortest
+         * block of data is a 10-byte image descriptor + 1-byte gif trailer
+         */
+        if (gif_bytes < 12) {
+                return GIF_INSUFFICIENT_FRAME_DATA;
+        }
+
+        /* Save the buffer position */
+        save_buffer_position = gif->buffer_position;
+        gif->buffer_position = gif_data - gif->gif_data;
+
+        /* Skip any extensions because they have allready been processed */
+        if ((return_value = gif_skip_frame_extensions(gif)) != GIF_OK) {
+                goto gif_decode_frame_exit;
+        }
+        gif_data = (gif->gif_data + gif->buffer_position);
+        gif_bytes = (gif_end - gif_data);
+
+        /* Ensure we have enough data for the 10-byte image descriptor + 1-byte
+         * gif trailer
+         */
+        if (gif_bytes < 12) {
+                return_value = GIF_INSUFFICIENT_FRAME_DATA;
+                goto gif_decode_frame_exit;
+        }
+
+        /* 10-byte Image Descriptor is:
+         *
+         *	+0	CHAR	Image Separator (0x2c)
+         *	+1	SHORT	Image Left Position
+         *	+3	SHORT	Image Top Position
+         *	+5	SHORT	Width
+         *	+7	SHORT	Height
+         *	+9	CHAR	__Packed Fields__
+         *			1BIT	Local Colour Table Flag
+         *			1BIT	Interlace Flag
+         *			1BIT	Sort Flag
+         *			2BITS	Reserved
+         *			3BITS	Size of Local Colour Table
+         */
+        if (gif_data[0] != GIF_IMAGE_SEPARATOR) {
+                return_value = GIF_DATA_ERROR;
+                goto gif_decode_frame_exit;
+        }
+        offset_x = gif_data[1] | (gif_data[2] << 8);
+        offset_y = gif_data[3] | (gif_data[4] << 8);
+        width = gif_data[5] | (gif_data[6] << 8);
+        height = gif_data[7] | (gif_data[8] << 8);
+
+        /* Boundary checking - shouldn't ever happen except unless the data has
+         * been modified since initialisation.
+         */
+        if ((offset_x + width > gif->width) ||
+            (offset_y + height > gif->height)) {
+                return_value = GIF_DATA_ERROR;
+                goto gif_decode_frame_exit;
+        }
+
+        /* Decode the flags */
+        flags = gif_data[9];
+        colour_table_size = 2 << (flags & GIF_COLOUR_TABLE_SIZE_MASK);
+        interlace = flags & GIF_INTERLACE_MASK;
+
+        /* Advance data pointer to next block either colour table or image
+         * data.
+         */
+        gif_data += 10;
+        gif_bytes = (gif_end - gif_data);
+
+        /* Set up the colour table */
+        if (flags & GIF_COLOUR_TABLE_MASK) {
+                if (gif_bytes < (int)(3 * colour_table_size)) {
+                        return_value = GIF_INSUFFICIENT_FRAME_DATA;
+                        goto gif_decode_frame_exit;
+                }
+                colour_table = gif->local_colour_table;
+                if (!clear_image) {
+                        for (index = 0; index < colour_table_size; index++) {
+                                /* Gif colour map contents are r,g,b.
+                                 *
+                                 * We want to pack them bytewise into the
+                                 * colour table, such that the red component
+                                 * is in byte 0 and the alpha component is in
+                                 * byte 3.
+                                 */
+                                unsigned char *entry =
+                                        (unsigned char *) &colour_table[index];
+
+                                entry[0] = gif_data[0];	/* r */
+                                entry[1] = gif_data[1];	/* g */
+                                entry[2] = gif_data[2];	/* b */
+                                entry[3] = 0xff;	/* a */
+
+                                gif_data += 3;
+                        }
+                } else {
+                        gif_data += 3 * colour_table_size;
+                }
+                gif_bytes = (gif_end - gif_data);
+        } else {
+                colour_table = gif->global_colour_table;
+        }
+
+        /* Ensure sufficient data remains */
+        if (gif_bytes < 1) {
+                return_value = GIF_INSUFFICIENT_FRAME_DATA;
+                goto gif_decode_frame_exit;
+        }
+
+        /* check for an end marker */
+        if (gif_data[0] == GIF_TRAILER) {
+                return_value = GIF_OK;
+                goto gif_decode_frame_exit;
+        }
+
+        /* Get the frame data */
+        assert(gif->bitmap_callbacks.bitmap_get_buffer);
+        frame_data = (void *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
+        if (!frame_data) {
+                return GIF_INSUFFICIENT_MEMORY;
+        }
+
+        /* If we are clearing the image we just clear, if not decode */
+        if (!clear_image) {
+                /* Ensure we have enough data for a 1-byte LZW code size +
+                 * 1-byte gif trailer
+                 */
+                if (gif_bytes < 2) {
+                        return_value = GIF_INSUFFICIENT_FRAME_DATA;
+                        goto gif_decode_frame_exit;
+                }
+
+                /* If we only have a 1-byte LZW code size + 1-byte gif trailer,
+                 * we're finished
+                 */
+                if ((gif_bytes == 2) && (gif_data[1] == GIF_TRAILER)) {
+                        return_value = GIF_OK;
+                        goto gif_decode_frame_exit;
+                }
+
+                /* If the previous frame's disposal method requires we restore
+                 * the background colour or this is the first frame, clear
+                 * the frame data
+                 */
+                if ((frame == 0) || (gif->decoded_frame == GIF_INVALID_FRAME)) {
+                        memset((char*)frame_data,
+                               GIF_TRANSPARENT_COLOUR,
+                               gif->width * gif->height * sizeof(int));
+                        gif->decoded_frame = frame;
+                        /* The line below would fill the image with its
+                         * background color, but because GIFs support
+                         * transparency we likely wouldn't want to do that. */
+                        /* memset((char*)frame_data, colour_table[gif->background_index], gif->width * gif->height * sizeof(int)); */
+                } else if ((frame != 0) &&
+                           (gif->frames[frame - 1].disposal_method == GIF_FRAME_CLEAR)) {
+                        clear_image = true;
+                        if ((return_value = gif_decode_frame(gif, (frame - 1))) != GIF_OK) {
+                                goto gif_decode_frame_exit;
+                        }
+                        clear_image = false;
+                        /*
+                         * If the previous frame's disposal method requires we
+                         * restore the previous image, find the last image set
+                         * to "do not dispose" and get that frame data
+                         */
+                } else if ((frame != 0) &&
+                           (gif->frames[frame - 1].disposal_method == GIF_FRAME_RESTORE)) {
+                        while ((last_undisposed_frame != -1) &&
+                               (gif->frames[--last_undisposed_frame].disposal_method == GIF_FRAME_RESTORE));
+
+                        /* If we don't find one, clear the frame data */
+                        if (last_undisposed_frame == -1) {
+                                /* see notes above on transparency
+                                 * vs. background color */
+                                memset((char*)frame_data,
+                                       GIF_TRANSPARENT_COLOUR,
+                                       gif->width * gif->height * sizeof(int));
+                        } else {
+                                if ((return_value = gif_decode_frame(gif, last_undisposed_frame)) != GIF_OK) {
+                                        goto gif_decode_frame_exit;
+                                }
+                                /* Get this frame's data */
+                                assert(gif->bitmap_callbacks.bitmap_get_buffer);
+                                frame_data = (void *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
+                                if (!frame_data) {
+                                        return GIF_INSUFFICIENT_MEMORY;
+                                }
+                        }
+                }
+                gif->decoded_frame = frame;
+
+                /* Initialise the LZW decoding */
+                set_code_size = gif_data[0];
+                gif->buffer_position = (gif_data - gif->gif_data) + 1;
+
+                /* Set our code variables */
+                code_size = set_code_size + 1;
+                clear_code = (1 << set_code_size);
+                end_code = clear_code + 1;
+                max_code_size = clear_code << 1;
+                max_code = clear_code + 2;
+                curbit = lastbit = 0;
+                last_byte = 2;
+                get_done = false;
+                direct = buf;
+                gif_init_LZW(gif);
+
+                /* Decompress the data */
+                for (y = 0; y < height; y++) {
+                        if (interlace) {
+                                decode_y = gif_interlaced_line(height, y) + offset_y;
+                        } else {
+                                decode_y = y + offset_y;
+                        }
+                        frame_scanline = frame_data + offset_x + (decode_y * gif->width);
+
+                        /* Rather than decoding pixel by pixel, we try to burst
+                         * out streams of data to remove the need for end-of
+                         * data checks every pixel.
+                         */
+                        x = width;
+                        while (x > 0) {
+                                burst_bytes = (stack_pointer - stack);
+                                if (burst_bytes > 0) {
+                                        if (burst_bytes > x) {
+                                                burst_bytes = x;
+                                        }
+                                        x -= burst_bytes;
+                                        while (burst_bytes-- > 0) {
+                                                colour = *--stack_pointer;
+                                                if (((gif->frames[frame].transparency) &&
+                                                     (colour != gif->frames[frame].transparency_index)) ||
+                                                    (!gif->frames[frame].transparency)) {
+                                                        *frame_scanline = colour_table[colour];
+                                                }
+                                                frame_scanline++;
+                                        }
+                                } else {
+                                        if (!gif_next_LZW(gif)) {
+                                                /* Unexpected end of frame, try to recover */
+                                                if (gif->current_error == GIF_END_OF_FRAME) {
+                                                        return_value = GIF_OK;
+                                                } else {
+                                                        return_value = gif->current_error;
+                                                }
+                                                goto gif_decode_frame_exit;
+                                        }
+                                }
+                        }
+                }
+        } else {
+                /* Clear our frame */
+                if (gif->frames[frame].disposal_method == GIF_FRAME_CLEAR) {
+                        for (y = 0; y < height; y++) {
+                                frame_scanline = frame_data + offset_x + ((offset_y + y) * gif->width);
+                                if (gif->frames[frame].transparency) {
+                                        memset(frame_scanline,
+                                               GIF_TRANSPARENT_COLOUR,
+                                               width * 4);
+                                } else {
+                                        memset(frame_scanline,
+                                               colour_table[gif->background_index],
+                                               width * 4);
+                                }
+                        }
+                }
+        }
+gif_decode_frame_exit:
 
-/**
- * Initialise LZW decoding
- */
-void gif_init_LZW(gif_animation *gif) {
-	int i;
-
-	gif->current_error = 0;
-	if (clear_code >= (1 << GIF_MAX_LZW)) {
-		stack_pointer = stack;
-		gif->current_error = GIF_FRAME_DATA_ERROR;
-		return;
-	}
-
-	/* initialise our table */
-	memset(table, 0x00, (1 << GIF_MAX_LZW) * 8);
-	for (i = 0; i < clear_code; ++i)
-		table[1][i] = i;
-
-	/* update our LZW parameters */
-	code_size = set_code_size + 1;
-	max_code_size = clear_code << 1;
-	max_code = clear_code + 2;
-	stack_pointer = stack;
-	do {
-		firstcode = oldcode = gif_next_code(gif, code_size);
-	} while (firstcode == clear_code);
-	*stack_pointer++ =firstcode;
-}
+        /* Check if we should test for optimisation */
+        if (gif->frames[frame].virgin) {
+                if (gif->bitmap_callbacks.bitmap_test_opaque) {
+                        gif->frames[frame].opaque = gif->bitmap_callbacks.bitmap_test_opaque(gif->frame_image);
+                } else {
+                        gif->frames[frame].opaque = false;
+                }
+                gif->frames[frame].virgin = false;
+        }
+
+        if (gif->bitmap_callbacks.bitmap_set_opaque) {
+                gif->bitmap_callbacks.bitmap_set_opaque(gif->frame_image, gif->frames[frame].opaque);
+        }
 
+        if (gif->bitmap_callbacks.bitmap_modified) {
+                gif->bitmap_callbacks.bitmap_modified(gif->frame_image);
+        }
 
-static bool gif_next_LZW(gif_animation *gif) {
-	int code, incode;
-	int block_size;
-	int new_code;
-
-	code = gif_next_code(gif, code_size);
-	if (code < 0) {
-	  	gif->current_error = code;
-		return false;
-	} else if (code == clear_code) {
-		gif_init_LZW(gif);
-		return true;
-	} else if (code == end_code) {
-		/* skip to the end of our data so multi-image GIFs work */
-		if (zero_data_block) {
-			gif->current_error = GIF_FRAME_DATA_ERROR;
-			return false;
-		}
-		block_size = 0;
-		while (block_size != 1 &&
-				gif->buffer_position < gif->buffer_size) {
-			block_size = gif->gif_data[gif->buffer_position] + 1;
-			gif->buffer_position += block_size;
-		}
-		gif->current_error = GIF_FRAME_DATA_ERROR;
-		return false;
-	}
-
-	incode = code;
-	if (code >= max_code) {
-		if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2)) {
-			gif->current_error = GIF_FRAME_DATA_ERROR;
-			return false;
-		}
-		*stack_pointer++ = firstcode;
-		code = oldcode;
-	}
-
-	/* The following loop is the most important in the GIF decoding cycle as every
-	 * single pixel passes through it.
-	 *
-	 * Note: our stack is always big enough to hold a complete decompressed chunk. */
-	while (code >= clear_code) {
-		if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2) ||
-				code >= (1 << GIF_MAX_LZW)) {
-			gif->current_error = GIF_FRAME_DATA_ERROR;
-			return false;
-		}
-		*stack_pointer++ = table[1][code];
-		new_code = table[0][code];
-		if (new_code < clear_code) {
-			code = new_code;
-			break;
-		}
-
-		if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2) ||
-				new_code >= (1 << GIF_MAX_LZW)) {
-			gif->current_error = GIF_FRAME_DATA_ERROR;
-			return false;
-		}
-		*stack_pointer++ = table[1][new_code];
-		code = table[0][new_code];
-		if (code == new_code) {
-		  	gif->current_error = GIF_FRAME_DATA_ERROR;
-			return false;
-		}
-	}
-
-	if (stack_pointer >= stack + ((1 << GIF_MAX_LZW) * 2)) {
-		gif->current_error = GIF_FRAME_DATA_ERROR;
-		return false;
-	}
-	*stack_pointer++ = firstcode = table[1][code];
-
-	if ((code = max_code) < (1 << GIF_MAX_LZW)) {
-		table[0][code] = oldcode;
-		table[1][code] = firstcode;
-		++max_code;
-		if ((max_code >= max_code_size) && (max_code_size < (1 << GIF_MAX_LZW))) {
-			max_code_size = max_code_size << 1;
-			++code_size;
-		}
-	}
-	oldcode = incode;
-	return true;
+        /* Restore the buffer position */
+        gif->buffer_position = save_buffer_position;
+
+        return return_value;
 }
 
-static int gif_next_code(gif_animation *gif, int code_size) {
-	int i, j, end, count, ret;
-	unsigned char *b;
-
-	end = curbit + code_size;
-	if (end >= lastbit) {
-		if (get_done)
-			return GIF_END_OF_FRAME;
-		buf[0] = direct[last_byte - 2];
-		buf[1] = direct[last_byte - 1];
-
-		/* get the next block */
-		direct = gif->gif_data + gif->buffer_position;
-		if (gif->buffer_position >= gif->buffer_size)
-			return GIF_INSUFFICIENT_FRAME_DATA;
-		zero_data_block = ((count = direct[0]) == 0);
-		if ((gif->buffer_position + count) >= gif->buffer_size)
-			return GIF_INSUFFICIENT_FRAME_DATA;
-		if (count == 0)
-			get_done = true;
-		else {
-			if (gif->buffer_position + 3 >= gif->buffer_size)
-				return GIF_INSUFFICIENT_FRAME_DATA;
-			direct -= 1;
-			buf[2] = direct[2];
-			buf[3] = direct[3];
-		}
-		gif->buffer_position += count + 1;
-
-		/* update our variables */
-		last_byte = 2 + count;
-		curbit = (curbit - lastbit) + 16;
-		lastbit = (2 + count) << 3;
-		end = curbit + code_size;
-	}
-
-	i = curbit >> 3;
-	if (i < 2)
-		b = buf;
-	else
-		b = direct;
-
-	ret = b[i];
-	j = (end >> 3) - 1;
-	if (i <= j) {
-		ret |= (b[i + 1] << 8);
-		if (i < j)
-			ret |= (b[i + 2] << 16);
-	}
-	ret = (ret >> (curbit % 8)) & maskTbl[code_size];
-	curbit += code_size;
-	return ret;
+
+/* exported function documented in libnsgif.h */
+void gif_finalise(gif_animation *gif)
+{
+        /* Release all our memory blocks */
+        if (gif->frame_image) {
+                assert(gif->bitmap_callbacks.bitmap_destroy);
+                gif->bitmap_callbacks.bitmap_destroy(gif->frame_image);
+        }
+
+        gif->frame_image = NULL;
+        free(gif->frames);
+        gif->frames = NULL;
+        free(gif->local_colour_table);
+        gif->local_colour_table = NULL;
+        free(gif->global_colour_table);
+        gif->global_colour_table = NULL;
 }