From 9b9815eec4231d9efea7cd5c6a18c09c2ebff310 Mon Sep 17 00:00:00 2001 From: Victor Vasiliev Date: Thu, 1 Dec 2011 20:45:44 +0400 Subject: Update developers documentation with coding conventions. Signed-off-by: Luca Barbato --- doc/developer.texi | 123 ++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 97 insertions(+), 26 deletions(-) (limited to 'doc') diff --git a/doc/developer.texi b/doc/developer.texi index 800009e89b..128b46e830 100644 --- a/doc/developer.texi +++ b/doc/developer.texi @@ -45,48 +45,61 @@ mailing list. @anchor{Coding Rules} @section Coding Rules -Libav is programmed in the ISO C90 language with a few additional -features from ISO C99, namely: +@subsection Code formatting conventions +The code is written in K&R C style. That means the following: @itemize @bullet @item -the @samp{inline} keyword; +The control statements are formatted by putting space betwen the statement and parenthesis +in the following way: +@example +for (i = 0; i < filter->input_count; i ++) @{ +@end example @item -@samp{//} comments; +The case statement is always located at the same level as the switch itself: +@example +switch (link->init_state) @{ +case AVLINK_INIT: + continue; +case AVLINK_STARTINIT: + av_log(filter, AV_LOG_INFO, "circular filter chain detected"); + return 0; +@end example @item -designated struct initializers (@samp{struct s x = @{ .i = 17 @};}) +Braces in function declarations are written on the new line: +@example +const char *avfilter_configuration(void) +@{ + return LIBAV_CONFIGURATION; +@} +@end example @item -compound literals (@samp{x = (struct s) @{ 17, 23 @};}) +In case of a single-statement if, no curly braces are required: +@example +if (!pic || !picref) + goto fail; +@end example +@item +Do not put spaces immediately inside parenthesis. @samp{if (ret)} is a valid style; @samp{if ( ret )} is not. @end itemize -These features are supported by all compilers we care about, so we will not -accept patches to remove their use unless they absolutely do not impair -clarity and performance. - -All code must compile with recent versions of GCC and a number of other -currently supported compilers. To ensure compatibility, please do not use -additional C99 features or GCC extensions. Especially watch out for: +There are the following guidelines regarding the indentation in files: @itemize @bullet @item -mixing statements and declarations; -@item -@samp{long long} (use @samp{int64_t} instead); -@item -@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar; -@item -GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}). -@end itemize - Indent size is 4. -The presentation is one inspired by 'indent -i4 -kr -nut'. +@item The TAB character is forbidden outside of Makefiles as is any form of trailing whitespace. Commits containing either will be rejected by the git repository. +@item +You should try to limit your code lines to 80 characters; however, do so if and only if this improves readability. +@end itemize +The presentation is one inspired by 'indent -i4 -kr -nut'. The main priority in Libav is simplicity and small code size in order to minimize the bug count. -Comments: Use the JavaDoc/Doxygen -format (see examples below) so that code documentation +@subsection Comments +Use the JavaDoc/Doxygen format (see examples below) so that code documentation can be generated automatically. All nontrivial functions should have a comment above them explaining what the function does, even if it is just one sentence. All structures and their member variables should be documented, too. @@ -120,11 +133,69 @@ int myfunc(int my_parameter) ... @end example +@subsection C language features + +Libav is programmed in the ISO C90 language with a few additional +features from ISO C99, namely: +@itemize @bullet +@item +the @samp{inline} keyword; +@item +@samp{//} comments; +@item +designated struct initializers (@samp{struct s x = @{ .i = 17 @};}) +@item +compound literals (@samp{x = (struct s) @{ 17, 23 @};}) +@end itemize + +These features are supported by all compilers we care about, so we will not +accept patches to remove their use unless they absolutely do not impair +clarity and performance. + +All code must compile with recent versions of GCC and a number of other +currently supported compilers. To ensure compatibility, please do not use +additional C99 features or GCC extensions. Especially watch out for: +@itemize @bullet +@item +mixing statements and declarations; +@item +@samp{long long} (use @samp{int64_t} instead); +@item +@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar; +@item +GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}). +@end itemize + +@subsection Naming conventions +All names are using underscores (_), not CamelCase. For example, @samp{avfilter_get_video_buffer} is +a valid function name and @samp{AVFilterGetVideo} is not. The only exception from this are structure names; +they should always be in the CamelCase + +There are following conventions for naming variables and functions: +@itemize @bullet +@item +For local variables no prefix is required. +@item +For variables and functions declared as @code{static} no prefixes are required. +@item +For variables and functions used internally by the library, @code{ff_} prefix should be used. +For example, @samp{ff_w64_demuxer}. +@item +For variables and functions used internally across multiple libraries, use @code{avpriv_}. For example, +@samp{avpriv_aac_parse_header}. +@item +For exported names, each library has its own prefixes. Just check the existing code and name accordingly. +@end itemize + +@subsection Miscellanous conventions +@itemize @bullet +@item fprintf and printf are forbidden in libavformat and libavcodec, please use av_log() instead. - +@item Casts should be used only when necessary. Unneeded parentheses should also be avoided if they don't make the code easier to understand. +@end itemize @section Development Policy -- cgit v1.2.3