[libsigrokdecode.git] / HACKING

-------------------------------------------------------------------------------
HACKING
-------------------------------------------------------------------------------

Coding style
------------

This project is programmed using the Linux kernel coding style, see
http://lxr.linux.no/linux/Documentation/CodingStyle for details.

Please use the same style for any code contributions, thanks!

The Python decoders should follow the usual Python conventions and use
Python idioms as far as it makes sense. The coding style should mostly follow
the Python PEP-8, which includes the convention of 4 spaces for indentation.
See http://www.python.org/dev/peps/pep-0008/ for details.


Contributions
-------------

 - Patches should be sent to the development mailinglist at
   sigrok-devel@lists.sourceforge.net (please subscribe to the list first).

   https://lists.sourceforge.net/lists/listinfo/sigrok-devel

 - Alternatively, you can also clone the git repository and let us know
   from where to pull/review your changes. You can use gitorious.org,
   github.com, or any other public git hosting site.


Random notes
------------

 - Consistently use g_try_malloc() / g_try_malloc0(). Do not use standard
   malloc()/calloc() if it can be avoided (sometimes other libs such
   as libftdi can return malloc()'d memory, for example).

 - Always properly match allocations with the proper *free() functions. If
   glib's g_try_malloc()/g_try_malloc0() was used, use g_free() to free the
   memory. Otherwise use standard free(). Never use the wrong function!

 - Never use g_malloc() or g_malloc0(). These functions do not return NULL
   if not enough memory is available but rather lead to an exit() or segfault
   instead. This behaviour is not acceptable for libraries.
   Use g_try_malloc()/g_try_malloc0() instead and check the return value.

 - You should never print any messages (neither to stdout nor stderr nor
   elsewhere) "manually" via e.g. printf() or g_log() or similar functions.
   Only srd_err()/srd_warn()/srd_info()/srd_dbg()/srd_spew() should be used.

 - Use glib's gboolean / TRUE / FALSE for boolean types consistently.
   Do not use <stdbool.h> and its true / false, and do not invent private
   definitions for this either.

 - Consistently use the same naming convention for #include guards in headers:
   <PROJECTNAME>_<PATH_TO_FILE>_<FILE>
   This ensures that all #include guards are always unique and consistent.
   Example: LIBSIGROKDECODE_SIGROKDECODE_INTERNAL_H

 - Consistently use the same naming convention for API functions:
   <libprefix>_<groupname>_<action>().

   Examples:
     srd_log_loglevel_set(), srd_log_loglevel_get(), srd_log_handler_set(),
     srd_log_handler_set_default(), and so on.

   Getter/setter function names should usually end with "_get" or "_set".
   Functions creating new "objects" should end with "_new".
   Functions destroying "objects" should end with "_destroy".
   Functions adding or removing items (e.g. from lists) should end with
   either "_add" or "_remove".
   Functions operating on all items from a list (not on only one of them),
   should end with "_all", e.g. "_remove_all", "_get_all", and so on.
   Use "_remove_all" in favor of "_clear" for consistency.


Doxygen
-------

 - In Doxygen comments, put an empty line between the block of @param lines
   and the final @return line. The @param lines themselves (if there is more
   than one) are not separated by empty lines.

 - Mark private functions (SRD_PRIV) with /** @private */, so that Doxygen
   doesn't include them in the output. Functions that are "static" anyway
   don't need to be marked like this.

 - Mark private variables/#defines with /** @cond PRIVATE */ and
   /** @endcond */, so that Doxygen doesn't include them in the output.
   Variables that are "static" don't need to be marked like this.

 - Mark all public API functions (SRD_API) with a @since tag which indicates
   in which release the respective function was added. If the function has
   existed before, but its API changed later, document this as well.

   Non-public functions (static ones, and those marked SRD_PRIV) don't need
   to have @since markers.

   The @since tag should be the last one, i.e. it should come after @param,
   @return, @see, and so on.

   Examples:

     @since 0.1.0

     @since 0.1.1 (but the API changed in 0.2.0)


Protocol decoder guidelines
---------------------------

 - The 'desc' metadata field for a protocol decoder, which contains a
   short, one-line description of the protocol/bus, should be at most 55
   characters long, and end with a full stop. This short description can be
   displayed on the command-line using "sigrok-cli -V -l 3", or in various
   different places in GUIs.

 - Longer, multi-line descriptions should be placed in the protocol
   decoder's __init__.py file as docstring. It can be viewed (for a specific
   protocol decoder, e.g., UART) via "sigrok-cli -a uart", or in various
   other places in GUIs.

 - Generally use strings for states (of the PD state machine), not integers.
   This avoids having to keep a list of state definitions at the top of file.
   The performance overhead for this is negligible in practice.

   Recommended:
     self.state = 'IDLE'
     self.state = 'GET STOP BIT'
   Not recommended:
     self.state = IDLE
     self.state = GET_STOP_BIT
     (where IDLE = 0 and GET_STOP_BIT = 1, for example)

 - Generally use strings for commands/IDs in generated protocol packets.
   This avoids having to know magic numbers of the PD in higher-level PDs.
   The performance overhead for this is negligible in practice.

   Recommended:
     self.put(x, y, p, ['STOPBIT', 0, 0])
     self.put(x, y, p, ['ADDRESS READ', 0x51])
   Not recommended:
     self.put(x, y, p, [STOPBIT, 0, 0])
     self.put(x, y, p, [ADDRESS_READ, 0x51])
     (with STOPBIT = 3 and ADDRESS_READ = 7, for example)

 - Use ALL-CAPS names for PD states and protocol packet commands/ID.
   Words should be separated by spaces (not underscores or the like).

   Recommended:
     'FIND ADDRESS', 'GET TEMPERATURE', 'START'
   Not recommended:
     'FIND_ADDRESS', 'Get Temperature', 'start'


Release engineering
-------------------

See

 http://sigrok.org/wiki/Developers/Release_process

for a list of items that need to be done when releasing a new tarball.
Commit	Line	Data
1859c480 UH	1	-------------------------------------------------------------------------------
	2	HACKING
	3	-------------------------------------------------------------------------------
	4
	5	Coding style
	6	------------
	7
	8	This project is programmed using the Linux kernel coding style, see
	9	http://lxr.linux.no/linux/Documentation/CodingStyle for details.
	10
	11	Please use the same style for any code contributions, thanks!
	12
	13	The Python decoders should follow the usual Python conventions and use
	14	Python idioms as far as it makes sense. The coding style should mostly follow
	15	the Python PEP-8, which includes the convention of 4 spaces for indentation.
	16	See http://www.python.org/dev/peps/pep-0008/ for details.
	17
	18
	19	Contributions
	20	-------------
	21
	22	- Patches should be sent to the development mailinglist at
	23	sigrok-devel@lists.sourceforge.net (please subscribe to the list first).
	24
	25	https://lists.sourceforge.net/lists/listinfo/sigrok-devel
	26
	27	- Alternatively, you can also clone the git repository and let us know
	28	from where to pull/review your changes. You can use gitorious.org,
	29	github.com, or any other public git hosting site.
	30
	31
	32	Random notes
	33	------------
	34
	35	- Consistently use g_try_malloc() / g_try_malloc0(). Do not use standard
	36	malloc()/calloc() if it can be avoided (sometimes other libs such
	37	as libftdi can return malloc()'d memory, for example).
	38
	39	- Always properly match allocations with the proper *free() functions. If
	40	glib's g_try_malloc()/g_try_malloc0() was used, use g_free() to free the
	41	memory. Otherwise use standard free(). Never use the wrong function!
	42
	43	- Never use g_malloc() or g_malloc0(). These functions do not return NULL
	44	if not enough memory is available but rather lead to an exit() or segfault
	45	instead. This behaviour is not acceptable for libraries.
	46	Use g_try_malloc()/g_try_malloc0() instead and check the return value.
	47
	48	- You should never print any messages (neither to stdout nor stderr nor
	49	elsewhere) "manually" via e.g. printf() or g_log() or similar functions.
	50	Only srd_err()/srd_warn()/srd_info()/srd_dbg()/srd_spew() should be used.
	51
	52	- Use glib's gboolean / TRUE / FALSE for boolean types consistently.
	53	Do not use <stdbool.h> and its true / false, and do not invent private
	54	definitions for this either.
	55
	56	- Consistently use the same naming convention for #include guards in headers:
	57	<PROJECTNAME>_<PATH_TO_FILE>_<FILE>
	58	This ensures that all #include guards are always unique and consistent.
	59	Example: LIBSIGROKDECODE_SIGROKDECODE_INTERNAL_H
	60
	61	- Consistently use the same naming convention for API functions:
	62	<libprefix>_<groupname>_<action>().
	63
	64	Examples:
65	srd_log_loglevel_set(), srd_log_loglevel_get(), srd_log_handler_set(),
66	srd_log_handler_set_default(), and so on.
67
68	Getter/setter function names should usually end with "_get" or "_set".
69	Functions creating new "objects" should end with "_new".
70	Functions destroying "objects" should end with "_destroy".
71	Functions adding or removing items (e.g. from lists) should end with
72	either "_add" or "_remove".
73	Functions operating on all items from a list (not on only one of them),
74	should end with "_all", e.g. "_remove_all", "_get_all", and so on.
75	Use "_remove_all" in favor of "_clear" for consistency.
76
31e615a5 UH	77
	78	Doxygen
	79	-------
	80
1859c480 UH	81	- In Doxygen comments, put an empty line between the block of @param lines
	82	and the final @return line. The @param lines themselves (if there is more
	83	than one) are not separated by empty lines.
	84
31e615a5 UH	85	- Mark private functions (SRD_PRIV) with /** @private */, so that Doxygen
	86	doesn't include them in the output. Functions that are "static" anyway
	87	don't need to be marked like this.
	88
	89	- Mark private variables/#defines with /** @cond PRIVATE */ and
	90	/** @endcond */, so that Doxygen doesn't include them in the output.
	91	Variables that are "static" don't need to be marked like this.
	92
f11e9498 UH	93	- Mark all public API functions (SRD_API) with a @since tag which indicates
	94	in which release the respective function was added. If the function has
	95	existed before, but its API changed later, document this as well.
	96
	97	Non-public functions (static ones, and those marked SRD_PRIV) don't need
	98	to have @since markers.
	99
	100	The @since tag should be the last one, i.e. it should come after @param,
	101	@return, @see, and so on.
	102
	103	Examples:
	104
	105	@since 0.1.0
	106
	107	@since 0.1.1 (but the API changed in 0.2.0)
	108
1859c480 UH	109
	110	Protocol decoder guidelines
	111	---------------------------
	112
	113	- The 'desc' metadata field for a protocol decoder, which contains a
	114	short, one-line description of the protocol/bus, should be at most 55
	115	characters long, and end with a full stop. This short description can be
	116	displayed on the command-line using "sigrok-cli -V -l 3", or in various
	117	different places in GUIs.
	118
	119	- Longer, multi-line descriptions should be placed in the protocol
	120	decoder's __init__.py file as docstring. It can be viewed (for a specific
	121	protocol decoder, e.g., UART) via "sigrok-cli -a uart", or in various
	122	other places in GUIs.
	123
	124	- Generally use strings for states (of the PD state machine), not integers.
	125	This avoids having to keep a list of state definitions at the top of file.
	126	The performance overhead for this is negligible in practice.
	127
	128	Recommended:
	129	self.state = 'IDLE'
	130	self.state = 'GET STOP BIT'
	131	Not recommended:
	132	self.state = IDLE
	133	self.state = GET_STOP_BIT
	134	(where IDLE = 0 and GET_STOP_BIT = 1, for example)
	135
	136	- Generally use strings for commands/IDs in generated protocol packets.
	137	This avoids having to know magic numbers of the PD in higher-level PDs.
	138	The performance overhead for this is negligible in practice.
	139
	140	Recommended:
	141	self.put(x, y, p, ['STOPBIT', 0, 0])
	142	self.put(x, y, p, ['ADDRESS READ', 0x51])
	143	Not recommended:
	144	self.put(x, y, p, [STOPBIT, 0, 0])
	145	self.put(x, y, p, [ADDRESS_READ, 0x51])
	146	(with STOPBIT = 3 and ADDRESS_READ = 7, for example)
	147
	148	- Use ALL-CAPS names for PD states and protocol packet commands/ID.
	149	Words should be separated by spaces (not underscores or the like).
	150
	151	Recommended:
	152	'FIND ADDRESS', 'GET TEMPERATURE', 'START'
	153	Not recommended:
	154	'FIND_ADDRESS', 'Get Temperature', 'start'
	155
	156
	157	Release engineering
	158	-------------------
	159
	160	See
	161
	162	http://sigrok.org/wiki/Developers/Release_process
	163
	164	for a list of items that need to be done when releasing a new tarball.
	165