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authorSebastian Huber <sebastian.huber@embedded-brains.de>2019-04-03 11:12:24 +0200
committerSebastian Huber <sebastian.huber@embedded-brains.de>2019-04-05 09:36:06 +0200
commitef1911298e3cfe5998bbc9fba243658ae36f471b (patch)
treef8e79c057e6460087b52b237fa85de30f97ff7da /eng
parent1d48fb5a0035362ee462172696043691a700a0cc (diff)
downloadrtems-docs-ef1911298e3cfe5998bbc9fba243658ae36f471b.tar.bz2
eng: Rework Doxygen guidelines
Update #3704.
Diffstat (limited to 'eng')
-rw-r--r--eng/coding-doxygen.rst676
1 files changed, 235 insertions, 441 deletions
diff --git a/eng/coding-doxygen.rst b/eng/coding-doxygen.rst
index a155de1..2f7682d 100644
--- a/eng/coding-doxygen.rst
+++ b/eng/coding-doxygen.rst
@@ -1,481 +1,275 @@
.. SPDX-License-Identifier: CC-BY-SA-4.0
-.. Copyright (C) 2018.
-.. COMMENT: RTEMS Foundation, The RTEMS Documentation Project
+.. Copyright (C) 2019 embedded brains GmbH
-General Doxygen Recommentations
-===============================
+Doxygen Guidelines
+==================
-.. COMMENT: TBD - Convert the following to Rest and insert into this file
-.. COMMENT: TBD - https://devel.rtems.org/wiki/Developer/Coding/Doxygen
-
-.. sidebar:: *History*
+Group Names
+-----------
- RTEMS is much older than Doxygen (http://www.doxygen.org/) and
- the documentation in the .h files was obviously not written with
- Doxygen markup in mind. In 2007, Joel Sherrill undertook to convert the
- documentation in the .h and .inl files in the RTEMS SuperCore? to Doxygen
- format. As a result of this effort, the Doxygen for the development
- version of the RTEMS is now built automatically periodically and made
- available on the RTEMS Website. In April 2008, Joel Sherrill began to
- update the Classic API (e.g. cpukit/rtems) .h files to include Doxygen
- markup. Now, RTEMS has nice Doxygen markup including state and sequence
- diagrams.
-
-Doxygen Best Practices
-----------------------
-
-* Do not use ``@a``. Instead use ``@param`` to document function parameters.
-* Do not use ``@return``. Instead use ``@retval`` to document return status
- codes.
-* Do not write documentation for trivial functions.
-* Do not repeat documentation, use ``@see`` for example.
-* Do not use ``@note``.
-* Use groups and arrange them in a hierarchy. Put every file into at least
- one group.
-* Use dot comments for state diagrams.
-* Use one whitespace character after an asterisk.
-
-Special Notes for Google Code-in Students
------------------------------------------
-
-Follow the directions given by the `Google Code-in
-<https://devel.rtems.org/wiki/GCI>`_ task and this should take
-care of itself if in doubt ask a mentor and/or tell a mentor the decision you
-made.
-
-Header File Example
--------------------
-
-`thread.h
-<https://git.rtems.org/rtems/tree/cpukit/include/rtems/score/thread.h>`_ and
-`threadimpl.h
-<https://git.rtems.org/rtems/tree/cpukit/include/rtems/score/threadimpl.h>`_
-should be a good example of how a header file shouldbe written. The following
-gives details in bits and pieces.
-
-Header blocks
--------------
-
-Header files should contain the similar comment blocks as other source files,
-described at :ref:`coding-file-hdr`.
-
-.. code-block:: c
-
- /**
- * @file
- *
- * @ingroup FlipFlop
- *
- * @brief Flip-Flop API
- */
-
- /*
- * Copyright (c) YYYY Author.
- *
- * The license and distribution terms for this file may be
- * found in the file LICENSE in this distribution or at
- * http://www.rtems.com/license/LICENSE.
- */
-
-Header guard
-------------
-
-After the comment blocks, use a header guard that assembles at least the
-include path of the file. For example, if ``flipflop.h`` is in
-``<rtems/lib/flipflop.h>`` then
-
-.. code-block:: c
-
- #ifndef RTEMS_LIB_FLIP_FLOP_H
- #define RTEMS_LIB_FLIP_FLOP_H
-
-Includes
---------
-
-Then add your include files before protecting C declarations from C++.
-
-.. code-block:: c
-
- #include <rtems.h>
-
- #ifdef __cplusplus
- extern "C" {
- #endif /* __cplusplus */
-
-Using @defgroup for group definitions
--------------------------------------
-
-Add any group definitions surrounding the function declarations that belong
-in that group. Rarely, a header may define more than one group. Here we use
-a dot diagram.
-
-.. code-block:: c
-
- /**
- * @defgroup FlipFlop Flip-Flop
- *
- * @brief Simple Flip-Flop state machine.
- *
- * @dot
- * digraph {
- * start [label="START"];
- * flip [label="FLIP"];
- * flop [label="FLOP"];
- * flip -> flop [label="flop()", URL="\ref flop"];
- * flop -> flip [label="flip()", URL="\ref flip"];
- * start -> flip
- * [label="flip_flop_initialize(FLIP)", URL="\ref flip_flop_initialize"];
- * start -> flop
- * [label="flip_flop_initialize(FLOP)", URL="\ref flip_flop_initialize"];
- * flip -> start
- * [label="flip_flop_restart()", URL="\ref flip_flop_restart"];
- * }
- * @enddot
- *
- * @{
- */
-
-enum and struct
----------------
-
-Provide documentation for declarations of enumerated types and structs.
-Use typedefs for structs, and do not use ``_t`` as a typename suffix.
-
-.. code-block:: c
-
- /**
- * @brief The set of possible flip-flop states.
- *
- * Enumerated type to define the set of states for a flip-flop.
- */
- typedef enum {
- START = 0,
- FLIP,
- FLOP
- } flip_flop_state;
-
- /**
- * @brief Object containing multiple flip-flops.
- *
- * Encapsulates multiple flip-flops.
- */
- typedef struct {
- /**
- * @brief Primary flip-flop.
- */
- flip_flop_state primary;
- /**
- * @brief Secondary flip-flop.
- */
- flip_flop_state secondary;
- } flip_flop_multiple;
-
-Using @name for organization
-----------------------------
-
-Complicated groups can be given additional organization by using ``@name``, or
-by declaring additional groups within the hierarchy of the header file's
-top-level group.
-
-.. code-block:: c
-
- /**
- * @name Flip-Flop Maintenance
- *
- * @{
- */
-
-Declaring functions
--------------------
-
-Function declarations should have an @brief that states what the function does
-in a single topic sentence starting with a descriptive verb in the present
-tense.
-
-.. code-block:: c
-
- /**
- * @brief Initializes the flip-flop state.
- *
- * @param[in] state The initial state to set the flip-flop.
- *
- * @retval RTEMS_SUCCESSFUL Successfully initialized.
- * @retval RTEMS_INCORRECT_STATE Flip-flop state is not valid.
- */
- rtems_status_code flip_flop_initialize(flip_flop_state state);
-
- /**
- * @brief Restarts the flip-flop.
- *
- * @retval RTEMS_SUCCESSFUL Successfully restarted.
- * @retval RTEMS_INCORRECT_STATE Flip-flop not in flip state.
- */
- rtems_status_code flip_flop_restart(void);
+Doxygen group names shall use
+`CamelCase <https://en.wikipedia.org/wiki/Camel_case>`_.
+In the RTEMS source code, CamelCase is rarely used, so this makes it easier to
+search and replace Doxygen groups. It avoids ambiguous references to
+functions, types, defines, macros, and groups. All groups shall have an
+``RTEMS`` prefix. This makes it possible to include the RTEMS files with
+Doxygen comments in a larger project without name conflicts.
-Do not document trivial functions, such as getter/setter methods.
+.. code:: c
-.. code-block:: c
+ /**
+ * @defgroup RTEMSScoreThread
+ *
+ * @ingrop RTEMSScore
+ *
+ * ...
+ */
- flip_flop_state flip_flop_current_state(void);
+Use Groups
+----------
-Close the documentation name definition and open a new name definition.
+Every file, function declaration, type definition, typedef, define, macro and
+global variable declaration shall belong to at least one Doxygen group. Use
+``@defgroup`` and ``@addtogroup`` with ``@{`` and ``@}`` brackets to add
+members to a group. A group shall be defined at most once. Each group shall
+be documented with an ``@brief`` description and an optional detailed
+description. The ``@brief`` description shall use
+`Title Case <https://en.wikipedia.org/wiki/Letter_case#Title_Case>`_.
+Use grammatically correct sentences for the detailed descriptions.
-.. code-block:: c
+.. code:: c
- /** @} */
+ /**
+ * @defgroup RTEMSScoreThread
+ *
+ * @ingrop RTEMSScore
+ *
+ * @brief Thread Handler
+ *
+ * ...
+ *
+ * @{
+ */
- /**
- * @name Flip-Flop Usage
- *
- * @{
- */
+ ... declarations, defines ...
- /**
- * @brief Flip operation.
- *
- * @retval RTEMS_SUCCESSFUL Flipped successfully.
- * @retval RTEMS_INCORRECT_STATE Incorrect state for flip operation.
- */
- rtems_status_code flip( void );
-
- /**
- * @brief Flop operation.
- *
- * @retval RTEMS_SUCCESSFUL Flopped successfully.
- * @retval RTEMS_INCORRECT_STATE Incorrect state for flop operation.
- */
- rtems_status_code flop( void );
-
- /** @} */
-
-Ending the file
----------------
-
-Close the documentation group definition, then the extern C declarations,
-then the header guard.
-
-.. code-block:: c
-
- /** @} */
-
- #ifdef __cplusplus
- }
- #endif /* __cplusplus */
-
- #endif /* RTEMS_LIB_FLIP_FLOP_H */
-
- No newline at the end of the file.
-
-Source File Example
--------------------
-
-.. code-block:: c
-
- /**
- * @file
- *
- * @ingroup FlipFlop
- *
- * @brief Flip-Flop implementation.
- */
-
- /*
- * Copyright (c) YYYY Author.
- *
- * The license and distribution terms for this file may be
- * found in the file LICENSE in this distribution or at
- * http://www.rtems.com/license/LICENSE.
- */
-
- #include <rtems/lib/flipflop.h>
-
- static flip_flop_state current_state;
-
- rtems_status_code flip_flop_initialize(flip_flop_state state)
- {
- if (current_state == START) {
- current_state = state;
-
- return RTEMS_SUCCESSFUL;
- } else {
- return RTEMS_INCORRECT_STATE;
- }
- }
+ /** @} */
- rtems_status_code flip_flop_restart(void)
- {
- if (current_state == FLIP) {
- current_state = START;
+.. code:: c
- return RTEMS_SUCCESSFUL;
- } else {
- return RTEMS_INCORRECT_STATE;
- }
- }
+ /**
+ * @addtogroup RTEMSScoreThread
+ *
+ * @{
+ */
- flip_flop_state flip_flop_current_state(void)
- {
- return current_state;
- }
+ ... declarations, defines ...
- rtems_status_code flip(void)
- {
- if (current_state == FLOP) {
- current_state = FLIP;
-
- return RTEMS_SUCCESSFUL;
- } else {
- return RTEMS_INCORRECT_STATE;
- }
- }
-
- rtems_status_code flop(void)
- {
- if (current_state == FLIP) {
- current_state = FLOP;
-
- return RTEMS_SUCCESSFUL;
- } else {
- return RTEMS_INCORRECT_STATE;
- }
- }
+ /** @} */
Files
-----
-Document files with the ``@file`` directive omitting the optional filename
-argument. Doxygen will infer the filename from the actual name of the file.
-Within one Doxygen run all files are unique and specified by the current
-Doxyfile. We can define how the generated output of path and filenames looks
-like in the Doxyfile via the ``FULL_PATH_NAMES``, ``STRIP_FROM_PATH`` and
-``STRIP_FROM_INC_PATH`` options.
-
-Functions
----------
-
-For documentation of function arguments there are basically to ways:
-
-The first one uses ``@param``:
-
-.. code-block:: c
-
- /**
- * @brief Copies from a source to a destination memory area.
- *
- * The source and destination areas may not overlap.
- *
- * @param[out] dest The destination memory area to copy to.
- * @param[in] src The source memory area to copy from.
- * @param[in] n The number of bytes to copy.
- */
-
-The second is to use ``@a`` param in descriptive text, for example:
-
-.. code-block:: c
- /**
- * Copies @a n bytes from a source memory area @a src to a destination memory
- * area @a dest, where both areas may not overlap.
- */
+Each source or header file shall have an ``@file`` block at the top of the
+file. The ``@file`` block should precede the license header separated by one
+blank line. This placement reduces the chance of merge conflicts in imported
+third-party code. The ``@file`` block shall be put into a group with
+``@ingroup GroupName``. The ``@file`` block should have an ``@brief``
+description and a detailed description if it is considered helpful. Use
+``@brief @copybrief GroupName`` as a default to copy the ``@brief`` description
+from the corresponding group and omit the detailed description.
-The ``@a`` indicates that the next word is a function argument and deserves
-some kind of highlighting. However, we feel that ``@a`` buries the usage of
-function arguments within description text. In RTEMS sources, we prefer to
-use ``@param`` instead of ``@a``.
+.. code:: c
-Doxyfile Hints
---------------
-
-Header Files
-~~~~~~~~~~~
-
-It is an RTEMS build feature that header files need to be installed in order to
-be useful. One workaround to generate documentation which allows automatic
-link generation is to use the installed header files as documentation input.
-Assume that we have the RTEMS sources in the rtems directory and the build of
-our BSP in build/powerpc-rtems5/mybsp relative to a common top-level directory.
-Then you can configure Doxygen like:
-
-.. code-block::
-
- INPUT = rtems/bsps/powerpc/mybsp \
- rtems/c/src/lib/libcpu/powerpc/mycpu \
- rtems/make/custom/mybsp.cfg \
- build/powerpc-rtems5/mybsp/lib/include/myincludes
-
- RECURSIVE = YES
-
- EXCLUDE = rtems/bsps/powerpc/mybsp/include \
- rtems/c/src/lib/libcpu/powerpc/mycpu/include
-
- FULL_PATH_NAMES = YES
-
- STRIP_FROM_PATH = build/powerpc-rtems5/mybsp/lib/include \
- rtems
-
-Script and Assembly Files
-~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Doxygen cannot cope with script (= files with #-like comments) or assembly
-files. But you can add filter programs for them
+ /**
+ * @file
+ *
+ * @ingroup RTEMSScoreThread
+ *
+ * @brief @copybrief RTEMSScoreThread
+ */
-.. COMMENT: TBD - Add source code for filter programs somewhere
+.. code:: c
-.. code-block::
+ /**
+ * @file
+ *
+ * @ingroup RTEMSScoreThread
+ *
+ * @brief Some helpful brief description.
+ *
+ * Some helpful detailed description.
+ */
- FILTER_PATTERNS = *.S=c-comments-only \
- *.s=c-comments-only \
- *.cfg=script-comments-only \
- *.am=script-comments-only \
- *.ac=script-comments-only
+Type Definitions
+----------------
-Assembly Example
-~~~~~~~~~~~~~~~~
+Each type defined in a header file shall be documented with an ``@brief``
+description and an optional detailed description. Each type member shall be
+documented with an ``@brief`` description and an optional detailed description.
+Use grammatically correct sentences for the detailed descriptions.
-.. code-block:: c
+.. code:: c
- /**
- * @fn void mpc55xx_fmpll_reset_config()
- *
- * @brief Configure FMPLL after reset.
- *
- * Sets the system clock from 12 MHz in two steps up to 128 MHz.
- */
- GLOBAL_FUNCTION mpc55xx_fmpll_reset_config
- /* Save link register */
- mflr r3
+ /**
+ * @brief The information structure used to manage each API class of objects.
+ *
+ * If objects for the API class are configured, an instance of this structure
+ * is statically allocated and pre-initialized by OBJECTS_INFORMATION_DEFINE()
+ * through <rtems/confdefs.h>. The RTEMS library contains a statically
+ * allocated and pre-initialized instance for each API class providing zero
+ * objects, see OBJECTS_INFORMATION_DEFINE_ZERO().
+ */
+ typedef struct {
+ /**
+ * @brief This is the maximum valid ID of this object API class.
+ *
+ * This member is statically initialized and provides also the object API,
+ * class and multiprocessing node information.
+ *
+ * It is used by _Objects_Get() to validate an object ID.
+ */
+ Objects_Id maximum_id;
+
+ ... more members ...
+ } Objects_Information;
+
+Function Declarations
+---------------------
+
+Each function declaration or function-like macros in a header file shall be
+documented with an ``@brief`` description and an optional detailed description.
+Use grammatically correct sentences for the brief and detailed descriptions.
+Each parameter shall be documented with an ``@param`` entry. List the
+``@param`` entries in the order of the function parameters. For *non-const
+pointer* parameters
+
+* use ``@param[out]``, if the referenced object is modified by the function, or
+
+* use ``@param[in, out]``, if the referenced object is read and modified by the
+ function.
+
+For other parameters (e.g. *const pointer* and *scalar* parameters) do not use
+the ``[in]``, ``[out]`` or ``[in, out]`` parameter specifiers. Each return
+value or return value range shall be documented with an ``@retval`` entry.
+Document the most common return value first. Use a placeholder name for value
+ranges, e.g. ``pointer`` in the ``_Workspace_Allocate()`` example below. In
+case the function returns only one value, then use ``@return``, e.g. use
+``@retval`` only if there are at least two return values or return value
+ranges. Use grammatically correct sentences for the parameter and return value
+descriptions.
+
+.. code:: c
- LA r4, FMPLL_SYNCR
+ /**
+ * @brief Sends a message to the message queue.
+ *
+ * This directive sends the message buffer to the message queue indicated by
+ * ID. If one or more tasks is blocked waiting to receive a message from this
+ * message queue, then one will receive the message. The task selected to
+ * receive the message is based on the task queue discipline algorithm in use
+ * by this particular message queue. If no tasks are waiting, then the message
+ * buffer will be placed at the rear of the chain of pending messages for this
+ * message queue.
+ *
+ * @param id The message queue ID.
+ * @param buffer The message content buffer.
+ * @param size The size of the message.
+ *
+ * @retval RTEMS_SUCCESSFUL Successful operation.
+ * @retval RTEMS_INVALID_ID Invalid message queue ID.
+ * @retval RTEMS_INVALID_ADDRESS The message buffer pointer is @c NULL.
+ * @retval RTEMS_INVALID_SIZE The message size is larger than the maximum
+ * message size of the message queue.
+ * @retval RTEMS_TOO_MANY The new message would exceed the message queue limit
+ * for pending messages.
+ */
+ rtems_status_code rtems_message_queue_send(
+ rtems_id id,
+ const void *buffer,
+ size_t size
+ );
-You have to put a declaration of this function somewhere in a header file.
+.. code:: c
-Script Example
-~~~~~~~~~~~~~~
+ /**
+ * @brief Receives a message from the message queue
+ *
+ * This directive is invoked when the calling task wishes to receive a message
+ * from the message queue indicated by ID. The received message is to be placed
+ * in the buffer. If no messages are outstanding and the option set indicates
+ * that the task is willing to block, then the task will be blocked until a
+ * message arrives or until, optionally, timeout clock ticks have passed.
+ *
+ * @param id The message queue ID.
+ * @param[out] buffer The buffer for the message content. The buffer must be
+ * large enough to store maximum size messages of this message queue.
+ * @param[out] size The size of the message.
+ * @param option_set The option set, e.g. RTEMS_NO_WAIT or RTEMS_WAIT.
+ * @param timeout The number of ticks to wait if the RTEMS_WAIT is set. Use
+ * RTEMS_NO_TIMEOUT to wait indefinitely.
+ *
+ * @retval RTEMS_SUCCESSFUL Successful operation.
+ * @retval RTEMS_INVALID_ID Invalid message queue ID.
+ * @retval RTEMS_INVALID_ADDRESS The message buffer pointer or the message size
+ * pointer is @c NULL.
+ * @retval RTEMS_TIMEOUT A timeout occurred and no message was received.
+ */
+ rtems_status_code rtems_message_queue_receive(
+ rtems_id id,
+ void *buffer,
+ size_t *size,
+ rtems_option option_set,
+ rtems_interval timeout
+ );
-.. code-block:: shell
+.. code:: c
- ##
- #
- # @file
- #
- # @ingroup mpc55xx_config
- #
- # @brief Configure script of LibBSP for the MPC55xx evaluation boards.
- #
+ /**
+ * @brief Allocates a memory block of the specified size from the workspace.
+ *
+ * @param size The size of the memory block.
+ *
+ * @retval pointer The pointer to the memory block. The pointer is at least
+ * aligned by CPU_HEAP_ALIGNMENT.
+ * @retval NULL No memory block with the requested size is available in the
+ * workspace.
+ */
+ void *_Workspace_Allocate( size_t size );
- AC_PREREQ([2.69])
- AC_INIT([rtems-c-src-lib-libbsp-powerpc-mpc55xxevb],[_RTEMS_VERSION],[https://devel.rtems.org/newticket])
+.. code:: c
+ /**
+ * @brief Rebalances the red-black tree after insertion of the node.
+ *
+ * @param[in, out] the_rbtree The red-black tree control.
+ * @param[in, out] the_node The most recently inserted node.
+ */
+ void _RBTree_Insert_color(
+ RBTree_Control *the_rbtree,
+ RBTree_Node *the_node
+ );
-GCC Attributes
---------------
+.. code:: c
-The Doxygen C/C++ parser cannot cope with the GCC ``attribute((something))``
-stuff. But you can discard such features with pre-defined preprocessor macros
+ /**
+ * @brief Builds an object ID from its components.
+ *
+ * @param the_api The object API.
+ * @param the_class The object API class.
+ * @param node The object node.
+ * @param index The object index.
+ *
+ * @return Returns the object ID constructed from the arguments.
+ */
+ #define _Objects_Build_id( the_api, the_class, node, index )
-.. code-block:: shell
+Header File Examples
+--------------------
- ENABLE_PREPROCESSING = YES
- MACRO_EXPANSION = YES
- EXPAND_ONLY_PREDEF = YES
- PREDEFINED = __attribute__(x)=
+The
+`<rtems/score/thread.h> <https://git.rtems.org/rtems/tree/cpukit/include/rtems/score/thread.h>`_
+and
+`<rtems/score/threadimpl.h> <https://git.rtems.org/rtems/tree/cpukit/include/rtems/score/threadimpl.h>`_
+header files are a good example of how header files should be documented.