codingstyle.html revision b8e80941
1b8e80941Smrg<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2b8e80941Smrg<html lang="en"> 3b8e80941Smrg<head> 4b8e80941Smrg <meta http-equiv="content-type" content="text/html; charset=utf-8"> 5b8e80941Smrg <title>Coding Style</title> 6b8e80941Smrg <link rel="stylesheet" type="text/css" href="mesa.css"> 7b8e80941Smrg</head> 8b8e80941Smrg<body> 9b8e80941Smrg 10b8e80941Smrg<div class="header"> 11b8e80941Smrg <h1>The Mesa 3D Graphics Library</h1> 12b8e80941Smrg</div> 13b8e80941Smrg 14b8e80941Smrg<iframe src="contents.html"></iframe> 15b8e80941Smrg<div class="content"> 16b8e80941Smrg 17b8e80941Smrg<h1>Coding Style</h1> 18b8e80941Smrg 19b8e80941Smrg<p> 20b8e80941SmrgMesa is over 20 years old and the coding style has evolved over time. 21b8e80941SmrgSome old parts use a style that's a bit out of date. 22b8e80941Smrg 23b8e80941SmrgDifferent sections of mesa can use different coding style as set in the local 24b8e80941SmrgEditorConfig (.editorconfig) and/or Emacs (.dir-locals.el) file. 25b8e80941Smrg 26b8e80941SmrgAlternatively the following is applicable. 27b8e80941Smrg 28b8e80941SmrgIf the guidelines below don't cover something, try following the format of 29b8e80941Smrgexisting, neighboring code. 30b8e80941Smrg</p> 31b8e80941Smrg 32b8e80941Smrg<p> 33b8e80941SmrgBasic formatting guidelines 34b8e80941Smrg</p> 35b8e80941Smrg 36b8e80941Smrg<ul> 37b8e80941Smrg<li>3-space indentation, no tabs. 38b8e80941Smrg<li>Limit lines to 78 or fewer characters. The idea is to prevent line 39b8e80941Smrgwrapping in 80-column editors and terminals. There are exceptions, such 40b8e80941Smrgas if you're defining a large, static table of information. 41b8e80941Smrg<li>Opening braces go on the same line as the if/for/while statement. 42b8e80941SmrgFor example: 43b8e80941Smrg<pre> 44b8e80941Smrg if (condition) { 45b8e80941Smrg foo; 46b8e80941Smrg } else { 47b8e80941Smrg bar; 48b8e80941Smrg } 49b8e80941Smrg</pre> 50b8e80941Smrg 51b8e80941Smrg<li>Put a space before/after operators. For example, <tt>a = b + c;</tt> 52b8e80941Smrgand not <tt>a=b+c;</tt> 53b8e80941Smrg 54b8e80941Smrg<li>This GNU indent command generally does the right thing for formatting: 55b8e80941Smrg<pre> 56b8e80941Smrg indent -br -i3 -npcs --no-tabs infile.c -o outfile.c 57b8e80941Smrg</pre> 58b8e80941Smrg 59b8e80941Smrg<li>Use comments wherever you think it would be helpful for other developers. 60b8e80941SmrgSeveral specific cases and style examples follow. Note that we roughly 61b8e80941Smrgfollow <a href="https://www.stack.nl/~dimitri/doxygen/">Doxygen</a> conventions. 62b8e80941Smrg<br> 63b8e80941Smrg<br> 64b8e80941SmrgSingle-line comments: 65b8e80941Smrg<pre> 66b8e80941Smrg /* null-out pointer to prevent dangling reference below */ 67b8e80941Smrg bufferObj = NULL; 68b8e80941Smrg</pre> 69b8e80941SmrgOr, 70b8e80941Smrg<pre> 71b8e80941Smrg bufferObj = NULL; /* prevent dangling reference below */ 72b8e80941Smrg</pre> 73b8e80941SmrgMulti-line comment: 74b8e80941Smrg<pre> 75b8e80941Smrg /* If this is a new buffer object id, or one which was generated but 76b8e80941Smrg * never used before, allocate a buffer object now. 77b8e80941Smrg */ 78b8e80941Smrg</pre> 79b8e80941SmrgWe try to quote the OpenGL specification where prudent: 80b8e80941Smrg<pre> 81b8e80941Smrg /* Page 38 of the PDF of the OpenGL ES 3.0 spec says: 82b8e80941Smrg * 83b8e80941Smrg * "An INVALID_OPERATION error is generated for any of the following 84b8e80941Smrg * conditions: 85b8e80941Smrg * 86b8e80941Smrg * * <length> is zero." 87b8e80941Smrg * 88b8e80941Smrg * Additionally, page 94 of the PDF of the OpenGL 4.5 core spec 89b8e80941Smrg * (30.10.2014) also says this, so it's no longer allowed for desktop GL, 90b8e80941Smrg * either. 91b8e80941Smrg */ 92b8e80941Smrg</pre> 93b8e80941SmrgFunction comment example: 94b8e80941Smrg<pre> 95b8e80941Smrg /** 96b8e80941Smrg * Create and initialize a new buffer object. Called via the 97b8e80941Smrg * ctx->Driver.CreateObject() driver callback function. 98b8e80941Smrg * \param name integer name of the object 99b8e80941Smrg * \param type one of GL_FOO, GL_BAR, etc. 100b8e80941Smrg * \return pointer to new object or NULL if error 101b8e80941Smrg */ 102b8e80941Smrg struct gl_object * 103b8e80941Smrg _mesa_create_object(GLuint name, GLenum type) 104b8e80941Smrg { 105b8e80941Smrg /* function body */ 106b8e80941Smrg } 107b8e80941Smrg</pre> 108b8e80941Smrg 109b8e80941Smrg<li>Put the function return type and qualifiers on one line and the function 110b8e80941Smrgname and parameters on the next, as seen above. This makes it easy to use 111b8e80941Smrg<code>grep ^function_name dir/*</code> to find function definitions. Also, 112b8e80941Smrgthe opening brace goes on the next line by itself (see above.) 113b8e80941Smrg 114b8e80941Smrg<li>Function names follow various conventions depending on the type of function: 115b8e80941Smrg<pre> 116b8e80941Smrg glFooBar() - a public GL entry point (in glapi_dispatch.c) 117b8e80941Smrg _mesa_FooBar() - the internal immediate mode function 118b8e80941Smrg save_FooBar() - retained mode (display list) function in dlist.c 119b8e80941Smrg foo_bar() - a static (private) function 120b8e80941Smrg _mesa_foo_bar() - an internal non-static Mesa function 121b8e80941Smrg</pre> 122b8e80941Smrg 123b8e80941Smrg<li>Constants, macros and enum names are ALL_UPPERCASE, with _ between 124b8e80941Smrgwords. 125b8e80941Smrg<li>Mesa usually uses camel case for local variables (Ex: "localVarname") 126b8e80941Smrgwhile gallium typically uses underscores (Ex: "local_var_name"). 127b8e80941Smrg<li>Global variables are almost never used because Mesa should be thread-safe. 128b8e80941Smrg 129b8e80941Smrg<li>Booleans. Places that are not directly visible to the GL API 130b8e80941Smrgshould prefer the use of <tt>bool</tt>, <tt>true</tt>, and 131b8e80941Smrg<tt>false</tt> over <tt>GLboolean</tt>, <tt>GL_TRUE</tt>, and 132b8e80941Smrg<tt>GL_FALSE</tt>. In C code, this may mean that 133b8e80941Smrg<tt>#include <stdbool.h></tt> needs to be added. The 134b8e80941Smrg<tt>try_emit_</tt>* methods in src/mesa/program/ir_to_mesa.cpp and 135b8e80941Smrgsrc/mesa/state_tracker/st_glsl_to_tgsi.cpp can serve as examples. 136b8e80941Smrg 137b8e80941Smrg</ul> 138b8e80941Smrg 139b8e80941Smrg</div> 140b8e80941Smrg</body> 141b8e80941Smrg</html> 142