233 lines
6.4 KiB
Plaintext
233 lines
6.4 KiB
Plaintext
RT-Thread Coding Style
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This is an developing instruction for RT-Thread developers. As an open source
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software, RT-Thread is done by the cooperation of different people. This
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document is a guide for RT-Thread developers and please obey it if you are.
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RT-Thread users could also get to know some conventions in the code through it
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and thus easier to understand the implementations of RT-Thread.
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1. Directory Naming
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In normal conditions, please name directories in lower-case. Directories should
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have descriptive names. For example, the port of a chip should be composed of
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the name of the chip and the category of the chip. Directories under components/
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should stand for what the component does.
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2. File Naming
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In normal conditions, please name files in lower-case. If the file is
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referencing other places, it can have the original name. To avoid naming
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collision, do not use general names or the names that are frequently used.
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3. Header Files
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To avoid include the same header file for multiple times, you need to define a
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symbol like this:
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#ifndef __FILE_H__
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#define __FILE_H__
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/* header file content */
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#endif
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The symbol should begin and end with "__" to avoid naming collision. The words
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of the file name should be connected by "_".
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4. Header File Comments
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In every header file, there should be copyright information and Change Log
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record like this:
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/*
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* File : rtthread.h
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* This file is part of RT-Thread RTOS
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* COPYRIGHT (C) 2006, RT-Thread Development Team
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.rt-thread.org/license/LICENSE.
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*
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* Change Logs:
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* Date Author Notes
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* 2006-03-18 Bernard the first version
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* 2006-04-26 Bernard add semaphore APIs
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* ...
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*/
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5. Structure Defines
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Please name structures in lower-case and connect words with "_". For example:
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struct rt_list_node
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{
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struct rt_list_node *next;
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struct rt_list_node *prev;
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};
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Braces should have their own lines and the members should be defines with
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indent.
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The names of type defines such like structure types should be the structure name
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plus "_t". For example:
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typedef struct rt_list_node rt_list_t;
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In order to be easily referenced, the types of objects in kernel is pointer. For
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example:
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typedef struct rt_timer* rt_timer_t;
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6. Macros
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In RT-Thread, please use upper-case names for macro definitions. Words are
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connected by "_". Like:
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#define RT_TRUE 1
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7. Function Naming and Declaration
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Please name functions in lower-case and separate words with "_". API provided to
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upper application should be declared in header files. If the function don't have
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parameters, it should be declared as void:
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rt_thread_t rt_thread_self(void);
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8. Commenting
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Please use English to comment. There shouldn't be too much comments and the
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comments should describe what does the code do. And it should describe how the
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complicated algorithm works. Comments to statements should be placed before them
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or right of them. Anther places are illegal.
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9. Indent
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Please use TAB or 4 spaces to indent. It's preferred to use 4 spaces. If no
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other special meanings, the indent should begin right after "{":
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if (condition)
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{
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/* others */
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}
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The only one exception is switch. In switch-case statements, "case" should be
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aligned with "switch":
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switch (value)
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{
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case value1:
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break;
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}
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"case" is aligned with "switch", the following code block should be indented.
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10. Braces and Spaces
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For ease of reading, it is advised that braces should occupy the whole line
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instead of following other statements. Like:
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if (condition)
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{
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/* others */
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}
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When matching braces have their own lines, the reader would identify the code
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blocks easily.
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There should be a space before parentheses when it's not a function call. For
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example:
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if (x <= y)
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{
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/* others */
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}
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for (index = 0; index < MAX_NUMBER; index ++)
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{
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/* others */
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}
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In expressions, there should be a space between most binary and ternary
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operators and the strings. No spaces around(inside) parentheses, like:
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if ( x <= y )
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{
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/* other */
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}
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This is a bad practice.
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11. trace, log Informations
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In RT-Thread, rt_kprintf is a commonly used logging routine. In RT-Thread
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rt_kprintf is implemented as a polling, non-interrupting string output. It is
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suitable in "instant" situations such as interrupt context. The polling method
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would have influence to the timing sequence of the log output.
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It is not recommended to use rt_kprintf frequently. Unless you are aware of that
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it's not a big deal to run slower.
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Logging should be off by default and can be turned on by a switch(e.g. a
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variable or a macro). When logging, it should be easy to understand and easy to
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determine where the problem is.
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12. Functions
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Functions in kernel should be K.I.S.S. If the function is too long, you should
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split it into smaller ones and make each of them simplified and easy to
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understand.
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13. Objects
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The kernel of RT-Thread uses object-oriented tech in C. The naming convention
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is: structure names are the object names, object names + verb phrases are the
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method names of objects:
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struct rt_timer
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{
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struct rt_object parent;
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/* other fields */
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};
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typedef struct rt_timer* rt_timer_t;
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The definition of structure rt_timer stands for the object definition of timer
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object.
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rt_timer_t rt_timer_create(const char* name,
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void (*timeout)(void* parameter), void* parameter,
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rt_tick_t time, rt_uint8_t flag);
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rt_err_t rt_timer_delete(rt_timer_t timer);
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rt_err_t rt_timer_start(rt_timer_t timer);
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rt_err_t rt_timer_stop(rt_timer_t timer);
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rt_timer + verb phrase stands for the method that could be used on timer object.
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When creating a new object, think twice on memory allocations: whether a static
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object could be created or it could only created dynamically on heap.
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14. Use astyle to format the code automatically
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parameters: --style=allman
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--indent=spaces=4
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--indent-preproc-block
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--pad-oper
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--pad-header
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--unpad-paren
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--suffix=none
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--align-pointer=name
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--lineend=linux
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--convert-tabs
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--verbose
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