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				5	<title>Coding Style</title>
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Erik Faye-Lund	ecdab0d	2019-05-06 13:26:47 +0200	[diff] [blame]	11	The Mesa 3D Graphics Library
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	12	</div>
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				16
				17	<h1>Coding Style</h1>
				18
				19	<p>
				20	Mesa is over 20 years old and the coding style has evolved over time.
				21	Some old parts use a style that's a bit out of date.
				22
				23	Different sections of mesa can use different coding style as set in the local
				24	EditorConfig (.editorconfig) and/or Emacs (.dir-locals.el) file.
				25
				26	Alternatively the following is applicable.
				27
				28	If the guidelines below don't cover something, try following the format of
				29	existing, neighboring code.
				30	</p>
				31
				32	<p>
				33	Basic formatting guidelines
				34	</p>
				35
				36	<ul>
				37	<li>3-space indentation, no tabs.
				38	<li>Limit lines to 78 or fewer characters. The idea is to prevent line
				39	wrapping in 80-column editors and terminals. There are exceptions, such
				40	as if you're defining a large, static table of information.
				41	<li>Opening braces go on the same line as the if/for/while statement.
				42	For example:
				43	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	44	if (condition) {
				45	foo;
				46	} else {
				47	bar;
				48	}
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	49	</pre>
				50
Erik Faye-Lund	0ee3669	2019-05-28 13:34:34 +0200	[diff] [blame]	51	<li>Put a space before/after operators. For example, <code>a = b + c;</code>
				52	and not <code>a=b+c;</code>
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	53
				54	<li>This GNU indent command generally does the right thing for formatting:
				55	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	56	indent -br -i3 -npcs --no-tabs infile.c -o outfile.c
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	57	</pre>
				58
Erik Faye-Lund	d60dc5d	2019-05-28 13:20:29 +0200	[diff] [blame]	59	<li>
				60	<p>Use comments wherever you think it would be helpful for other developers.
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	61	Several specific cases and style examples follow. Note that we roughly
Erik Faye-Lund	c59c793	2019-06-03 19:23:07 +0200	[diff] [blame]	62	follow <a href="http://www.doxygen.nl">Doxygen</a> conventions.
Erik Faye-Lund	d60dc5d	2019-05-28 13:20:29 +0200	[diff] [blame]	63	</p>
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	64	Single-line comments:
				65	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	66	/* null-out pointer to prevent dangling reference below */
				67	bufferObj = NULL;
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	68	</pre>
				69	Or,
				70	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	71	bufferObj = NULL; /* prevent dangling reference below */
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	72	</pre>
				73	Multi-line comment:
				74	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	75	/* If this is a new buffer object id, or one which was generated but
				76	* never used before, allocate a buffer object now.
				77	*/
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	78	</pre>
				79	We try to quote the OpenGL specification where prudent:
				80	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	81	/* Page 38 of the PDF of the OpenGL ES 3.0 spec says:
				82	*
				83	* "An INVALID_OPERATION error is generated for any of the following
				84	* conditions:
				85	*
				86	* * <length> is zero."
				87	*
				88	* Additionally, page 94 of the PDF of the OpenGL 4.5 core spec
				89	* (30.10.2014) also says this, so it's no longer allowed for desktop GL,
				90	* either.
				91	*/
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	92	</pre>
				93	Function comment example:
				94	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	95	/**
				96	* Create and initialize a new buffer object. Called via the
				97	* ctx->Driver.CreateObject() driver callback function.
				98	* \param name integer name of the object
				99	* \param type one of GL_FOO, GL_BAR, etc.
				100	* \return pointer to new object or NULL if error
				101	*/
				102	struct gl_object *
				103	_mesa_create_object(GLuint name, GLenum type)
				104	{
				105	/* function body */
				106	}
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	107	</pre>
				108
				109	<li>Put the function return type and qualifiers on one line and the function
				110	name and parameters on the next, as seen above. This makes it easy to use
				111	<code>grep ^function_name dir/*</code> to find function definitions. Also,
				112	the opening brace goes on the next line by itself (see above.)
				113
				114	<li>Function names follow various conventions depending on the type of function:
				115	<pre>
Erik Faye-Lund	9954120	2020-01-16 20:18:07 +0100	[diff] [blame]	116	glFooBar() - a public GL entry point (in glapi_dispatch.c)
				117	_mesa_FooBar() - the internal immediate mode function
				118	save_FooBar() - retained mode (display list) function in dlist.c
				119	foo_bar() - a static (private) function
				120	_mesa_foo_bar() - an internal non-static Mesa function
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	121	</pre>
				122
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	123	<li>Constants, macros and enum names are <code>ALL_UPPERCASE</code>, with _
				124	between words.
				125	<li>Mesa usually uses camel case for local variables (Ex:
				126	<code>localVarname</code>) while gallium typically uses underscores (Ex:
				127	<code>local_var_name</code>).
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	128	<li>Global variables are almost never used because Mesa should be thread-safe.
				129
				130	<li>Booleans. Places that are not directly visible to the GL API
Erik Faye-Lund	0ee3669	2019-05-28 13:34:34 +0200	[diff] [blame]	131	should prefer the use of <code>bool</code>, <code>true</code>, and
				132	<code>false</code> over <code>GLboolean</code>, <code>GL_TRUE</code>, and
				133	<code>GL_FALSE</code>. In C code, this may mean that
				134	<code>#include <stdbool.h></code> needs to be added. The
Erik Faye-Lund	f3235cf	2019-06-06 10:11:31 +0200	[diff] [blame]	135	<code>try_emit_*</code> methods in <code>src/mesa/program/ir_to_mesa.cpp</code>
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	136	and <code>src/mesa/state_tracker/st_glsl_to_tgsi.cpp</code> can serve as
				137	examples.
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	138
				139	</ul>
Emil Velikov	e561737	2016-11-16 00:31:26 +0000	[diff] [blame]	140
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