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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 | - Don't do variable declarations in compound statements, only at the | |
36 | beginning of a function. | |
37 | ||
38 | - Generally avoid assigning values to variables at declaration time, | |
39 | especially so for complex and/or run-time dependent values. | |
40 | ||
41 | - Consistently use g_try_malloc() / g_try_malloc0(). Do not use standard | |
42 | malloc()/calloc() if it can be avoided (sometimes other libs such | |
43 | as libftdi can return malloc()'d memory, for example). | |
44 | ||
45 | - Always properly match allocations with the proper *free() functions. If | |
46 | glib's g_try_malloc()/g_try_malloc0() was used, use g_free() to free the | |
47 | memory. Otherwise use standard free(). Never use the wrong function! | |
48 | ||
49 | - Never use g_malloc() or g_malloc0(). These functions do not return NULL | |
50 | if not enough memory is available but rather lead to an exit() or segfault | |
51 | instead. This behaviour is not acceptable for libraries. | |
52 | Use g_try_malloc()/g_try_malloc0() instead and check the return value. | |
53 | ||
54 | - You should never print any messages (neither to stdout nor stderr nor | |
55 | elsewhere) "manually" via e.g. printf() or g_log() or similar functions. | |
56 | Only srd_err()/srd_warn()/srd_info()/srd_dbg()/srd_spew() should be used. | |
57 | ||
58 | - Use glib's gboolean / TRUE / FALSE for boolean types consistently. | |
59 | Do not use <stdbool.h> and its true / false, and do not invent private | |
60 | definitions for this either. | |
61 | ||
62 | - Consistently use the same naming convention for #include guards in headers: | |
63 | <PROJECTNAME>_<PATH_TO_FILE>_<FILE> | |
64 | This ensures that all #include guards are always unique and consistent. | |
65 | Example: LIBSIGROKDECODE_LIBSIGROKDECODE_INTERNAL_H | |
66 | ||
67 | - Consistently use the same naming convention for API functions: | |
68 | <libprefix>_<groupname>_<action>(). | |
69 | ||
70 | Examples: | |
71 | srd_log_loglevel_set(), srd_log_loglevel_get(), srd_log_handler_set(), | |
72 | srd_log_handler_set_default(), and so on. | |
73 | ||
74 | Getter/setter function names should usually end with "_get" or "_set". | |
75 | Functions creating new "objects" should end with "_new". | |
76 | Functions destroying "objects" should end with "_destroy". | |
77 | Functions adding or removing items (e.g. from lists) should end with | |
78 | either "_add" or "_remove". | |
79 | Functions operating on all items from a list (not on only one of them), | |
80 | should end with "_all", e.g. "_remove_all", "_get_all", and so on. | |
81 | Use "_remove_all" in favor of "_clear" for consistency. | |
82 | ||
83 | - All enums should generally use an explicit start number of 10000. | |
84 | If there are multiple "categories" in the enum entries, each category | |
85 | should be 10000 entries apart from the next one. The start of categories | |
86 | are thus 10000, 20000, 30000, and so on. | |
87 | ||
88 | Adding items to an enum MUST always append to a "category", never add | |
89 | items in the middle of a category. The order of items MUST NOT be changed. | |
90 | Any of the above would break the ABI. | |
91 | ||
92 | The enum item 0 is special and is used as terminator in some lists, thus | |
93 | enums should not use this for "valid" entries (and start at 10000 instead). | |
94 | ||
95 | ||
96 | Doxygen | |
97 | ------- | |
98 | ||
99 | - In Doxygen comments, put an empty line between the block of @param lines | |
100 | and the final @return line. The @param lines themselves (if there is more | |
101 | than one) are not separated by empty lines. | |
102 | ||
103 | - Mark private functions (SRD_PRIV) with /** @private */, so that Doxygen | |
104 | doesn't include them in the output. Functions that are "static" anyway | |
105 | don't need to be marked like this. | |
106 | ||
107 | - Mark private variables/#defines with /** @cond PRIVATE */ and | |
108 | /** @endcond */, so that Doxygen doesn't include them in the output. | |
109 | Variables that are "static" don't need to be marked like this. | |
110 | ||
111 | - Mark all public API functions (SRD_API) with a @since tag which indicates | |
112 | in which release the respective function was added (e.g. "@since 0.1.0"). | |
113 | ||
114 | If the function has existed before, but its API changed later, the @since | |
115 | tag should mention only the release when the API last changed. | |
116 | ||
117 | Example: The srd_foo() call was added in 0.1.0, but the API changed in | |
118 | the later 0.2.0 release. The docs should read "@since 0.2.0" in that case. | |
119 | ||
120 | Non-public functions (static ones, and those marked SRD_PRIV) don't need | |
121 | to have @since markers. | |
122 | ||
123 | The @since tag should be the last one, i.e. it should come after @param, | |
124 | @return, @see, and so on. | |
125 | ||
126 | ||
127 | Protocol decoder guidelines | |
128 | --------------------------- | |
129 | ||
130 | - The 'desc' metadata field for a protocol decoder, which contains a | |
131 | short, one-line description of the protocol/bus, should be at most 55 | |
132 | characters long, and end with a full stop. This short description can be | |
133 | displayed on the command-line using "sigrok-cli -V -l 3", or in various | |
134 | different places in GUIs. | |
135 | ||
136 | - Longer, multi-line descriptions should be placed in the protocol | |
137 | decoder's __init__.py file as docstring. It can be viewed (for a specific | |
138 | protocol decoder, e.g., UART) via "sigrok-cli -a uart", or in various | |
139 | other places in GUIs. | |
140 | ||
141 | - Generally use strings for states (of the PD state machine), not integers. | |
142 | This avoids having to keep a list of state definitions at the top of file. | |
143 | The performance overhead for this is negligible in practice. | |
144 | ||
145 | Recommended: | |
146 | self.state = 'IDLE' | |
147 | self.state = 'GET STOP BIT' | |
148 | Not recommended: | |
149 | self.state = IDLE | |
150 | self.state = GET_STOP_BIT | |
151 | (where IDLE = 0 and GET_STOP_BIT = 1, for example) | |
152 | ||
153 | - Generally use strings for commands/IDs in generated protocol packets. | |
154 | This avoids having to know magic numbers of the PD in higher-level PDs. | |
155 | The performance overhead for this is negligible in practice. | |
156 | ||
157 | Recommended: | |
158 | self.put(x, y, p, ['STOPBIT', 0, 0]) | |
159 | self.put(x, y, p, ['ADDRESS READ', 0x51]) | |
160 | Not recommended: | |
161 | self.put(x, y, p, [STOPBIT, 0, 0]) | |
162 | self.put(x, y, p, [ADDRESS_READ, 0x51]) | |
163 | (with STOPBIT = 3 and ADDRESS_READ = 7, for example) | |
164 | ||
165 | - Use ALL-CAPS names for PD states and protocol packet commands/ID. | |
166 | Words should be separated by spaces (not underscores or the like). | |
167 | ||
168 | Recommended: | |
169 | 'FIND ADDRESS', 'GET TEMPERATURE', 'START' | |
170 | Not recommended: | |
171 | 'FIND_ADDRESS', 'Get Temperature', 'start' | |
172 | ||
173 | ||
174 | Testsuite | |
175 | --------- | |
176 | ||
177 | You can run the libsigrokdecode testsuite using: | |
178 | ||
179 | $ make check | |
180 | ||
181 | ||
182 | Protocol decoder test framework | |
183 | ------------------------------- | |
184 | ||
185 | Please see the sigrok-test repository for a protocol decoder test suite that | |
186 | checks the decoded data of various PDs against known-good reference data. | |
187 | ||
188 | ||
189 | Release engineering | |
190 | ------------------- | |
191 | ||
192 | See | |
193 | ||
194 | http://sigrok.org/wiki/Developers/Release_process | |
195 | ||
196 | for a list of items that need to be done when releasing a new tarball. | |
197 |