Git commit conventions ====================== Each commit message should start with a directory or full file path prefix, so it was clear which part of codebase a commit affects. If a change affects one file, it's better to use path to a file. If it affects few files in a subdirectory, using subdirectory as a prefix is ok. For longish paths, it's acceptable to drop intermediate components, which still should provide good context of a change. It's also ok to drop file extensions. Besides prefix, first line of a commit message should describe a change clearly and to the point, and be a grammatical sentence with final full stop. First line should fit within 78 characters. Examples of good first line of commit messages: py/objstr: Add splitlines() method. py: Rename FOO to BAR. docs/machine: Fix typo in reset() description. ports: Switch to use lib/foo instead of duplicated code. After the first line, add an empty line and in following lines describe a change in a detail, if needed. Any change beyond 5 lines would likely require such detailed description. To get good practical examples of good commits and their messages, browse the `git log` of the project. Python code conventions ======================= Python code follows [PEP 8](http://legacy.python.org/dev/peps/pep-0008/). Naming conventions: - Module names are short and all lowercase; eg pyb, stm. - Class names are CamelCase, with abbreviations all uppercase; eg I2C, not I2c. - Function and method names are all lowercase with words separated by a single underscore as necessary to improve readability; eg mem_read. - Constants are all uppercase with words separated by a single underscore; eg GPIO_IDR. C code conventions ================== When writing new C code, please adhere to the following conventions. White space: - Expand tabs to 4 spaces. - Don't leave trailing whitespace at the end of a line. - For control blocks (if, for, while), put 1 space between the keyword and the opening parenthesis. - Put 1 space after a comma, and 1 space around operators. Braces: - Use braces for all blocks, even no-line and single-line pieces of code. - Put opening braces on the end of the line it belongs to, not on a new line. - For else-statements, put the else on the same line as the previous closing brace. Header files: - Header files should be protected from multiple inclusion with #if directives. See an existing header for naming convention. Names: - Use underscore_case, not camelCase for all names. - Use CAPS_WITH_UNDERSCORE for enums and macros. - When defining a type use underscore_case and put '_t' after it. Integer types: MicroPython runs on 16, 32, and 64 bit machines, so it's important to use the correctly-sized (and signed) integer types. The general guidelines are: - For most cases use mp_int_t for signed and mp_uint_t for unsigned integer values. These are guaranteed to be machine-word sized and therefore big enough to hold the value from a MicroPython small-int object. - Use size_t for things that count bytes / sizes of objects. - You can use int/uint, but remember that they may be 16-bits wide. - If in doubt, use mp_int_t/mp_uint_t. Comments: - Be concise and only write comments for things that are not obvious. - Use `// ` prefix, NOT `/* ... */`. No extra fluff. Memory allocation: - Use m_new, m_renew, m_del (and friends) to allocate and free heap memory. These macros are defined in py/misc.h. Examples -------- Braces, spaces, names and comments: #define TO_ADD (123) // This function will always recurse indefinitely and is only used to show // coding style int foo_function(int x, int some_value) { if (x < some_value) { foo(some_value, x); } else { foo(x + TO_ADD, some_value - 1); } for (int my_counter = 0; my_counter < x; my_counter++) { } } Type declarations: typedef struct _my_struct_t { int member; void *data; } my_struct_t;