IABSD.fr/xenocara/lib/mesa/docs/codingstyle.rst

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• Author : jsg
  Date : 2022-09-02 05:12:48
  Hash : 4968d392
  Message : Import Mesa 22.1.7

• lib/mesa/docs/codingstyle.rst

• Coding Style
  ============
  
  Mesa is over 20 years old and the coding style has evolved over time.
  Some old parts use a style that's a bit out of date. Different sections
  of mesa can use different coding style as set in the local EditorConfig
  (.editorconfig) and/or Emacs (.dir-locals.el) file. Alternatively the
  following is applicable. If the guidelines below don't cover something,
  try following the format of existing, neighboring code.
  
  Basic formatting guidelines
  
  -  3-space indentation, no tabs.
  -  Limit lines to 78 or fewer characters. The idea is to prevent line
     wrapping in 80-column editors and terminals. There are exceptions,
     such as if you're defining a large, static table of information.
  -  Opening braces go on the same line as the if/for/while statement. For
     example:
  
     .. code-block:: c
  
        if (condition) {
           foo;
        } else {
           bar;
        }
  
  -  Put a space before/after operators. For example, ``a = b + c;`` and
     not ``a=b+c;``
  -  This GNU indent command generally does the right thing for
     formatting:
  
     .. code-block:: console
  
        indent -br -i3 -npcs --no-tabs infile.c -o outfile.c
  
  -  Use comments wherever you think it would be helpful for other
     developers. Several specific cases and style examples follow. Note
     that we roughly follow `Doxygen <http://www.doxygen.nl>`__
     conventions.
  
     Single-line comments:
  
     .. code-block:: c
  
        /* null-out pointer to prevent dangling reference below */
        bufferObj = NULL;
  
     Or,
  
     .. code-block:: c
  
        bufferObj = NULL;  /* prevent dangling reference below */
  
     Multi-line comment:
  
     .. code-block:: c
  
        /* If this is a new buffer object id, or one which was generated but
         * never used before, allocate a buffer object now.
         */
  
     We try to quote the OpenGL specification where prudent:
  
     .. code-block:: c
  
        /* Page 38 of the PDF of the OpenGL ES 3.0 spec says:
         *
         *     "An INVALID_OPERATION error is generated for any of the following
         *     conditions:
         *
         *     * <length> is zero."
         *
         * Additionally, page 94 of the PDF of the OpenGL 4.5 core spec
         * (30.10.2014) also says this, so it's no longer allowed for desktop GL,
         * either.
         */
  
     Function comment example:
  
     .. code-block:: c
  
        /**
         * Create and initialize a new buffer object.  Called via the
         * ctx->Driver.CreateObject() driver callback function.
         * \param  name  integer name of the object
         * \param  type  one of GL_FOO, GL_BAR, etc.
         * \return  pointer to new object or NULL if error
         */
        struct gl_object *
        _mesa_create_object(GLuint name, GLenum type)
        {
           /* function body */
        }
  
  -  Put the function return type and qualifiers on one line and the
     function name and parameters on the next, as seen above. This makes
     it easy to use ``grep ^function_name dir/*`` to find function
     definitions. Also, the opening brace goes on the next line by itself
     (see above.)
  -  Function names follow various conventions depending on the type of
     function:
  
     +---------------------+------------------------------------------+
     | Convention          | Explanation                              |
     +=====================+==========================================+
     | ``glFooBar()``      | a public GL entry point (in              |
     |                     | :file:`glapi_dispatch.c`)                |
     +---------------------+------------------------------------------+
     | ``_mesa_FooBar()``  | the internal immediate mode function     |
     +---------------------+------------------------------------------+
     | ``save_FooBar()``   | retained mode (display list) function in |
     |                     | :file:`dlist.c`                          |
     +---------------------+------------------------------------------+
     | ``foo_bar()``       | a static (private) function              |
     +---------------------+------------------------------------------+
     | ``_mesa_foo_bar()`` | an internal non-static Mesa function     |
     +---------------------+------------------------------------------+
  
  -  Constants, macros and enum names are ``ALL_UPPERCASE``, with \_
     between words.
  -  Mesa usually uses camel case for local variables (Ex:
     ``localVarname``) while Gallium typically uses underscores (Ex:
     ``local_var_name``).
  -  Global variables are almost never used because Mesa should be
     thread-safe.
  -  Booleans. Places that are not directly visible to the GL API should
     prefer the use of ``bool``, ``true``, and ``false`` over
     ``GLboolean``, ``GL_TRUE``, and ``GL_FALSE``. In C code, this may
     mean that ``#include <stdbool.h>`` needs to be added. The
     ``try_emit_*`` method ``src/mesa/state_tracker/st_glsl_to_tgsi.cpp``
     can serve as an example.