Coding Style

Basic Rules

The following rules are revised from

https://www.kernel.org/doc/html/latest/process/coding-style.html

and

https://bitbucket.org/multicoreware/x265/wiki/Coding

1. indentation

   • use 4 spaces

     if (condition) {
         statements
     }
     else {
         statements
     }
     

2. breaking long lines and strings (not a must)

   • keep lines within 80 characters

3. placing braces and spaces

   • for all non-function statement blocks, put the opening brace last on the line, and put the closing brace first

     if (condition) {
         statements
     }
     else {
         statements
     }
     

   • for functions, put the opening brace at the beginning of the next line

     int function(int variable)
     {
         statements;
     }
     

   • for single statements, omit braces

     if (condition)
         one statement;
     else
         one statement;
     

   • but for the following cases, still keep them

     if (condition) {
         one statement;
         one statement;
     }
     else {
         one statement;
     }
     
     if (condition) {
        if (condition) {
           if (condition)
              statement
        }
     }
     

4. spaces

   • use a space after the following keywords

     if, switch, case, for, do, while
     

   • but not with the following keywords

     sizeof, typeof, alignof, __attribute__
     

   • do not add spaces around parenthesized expressions

     if (condition)
     

   • adjacent * to the data name or function name

     int *variable;
     int *function(int variable);
     

   • use one space on each side of the following operators

     (where, &, *, … are used as binary or ternary operators)

     =, +, -, <, >, *, /, %, |, &, ^, <=, >=, ==, !=, ?, :
     

   • do not use space after the following operators

     (where, &, *, … are used as unary operators)

     &, *, +, -, ~, !, sizeof, typeof, alignof, __attribute__, defined
     

   • do not use space before the postfix increment or decrement unary operators

     ++, --
     

   • do not use space after the prefix increment or decrement unary operators

     ++, --
     

   • do not use space around member operators

     ., ->
     

   • do not leave trailing whitespace at the ends of lines

5. naming

   • use the “small camel case” for variables or functions

     int datCst
     int getDatCst()
     

   • use the “big camel case” or small camel case with postfix _t for type

     Cst* datCst
     cst_t* datCst    // I prefer this one
     

   • use the “big camel case” or capitalization for class

     class Add
     class ADD    // I prefer this one
     

   • use the “big camel case” or capitalization for definitions or enums

     #define MACRO    value
     enums class enmCst_t{
        SAD = 0,
        SATD
     }
     

   • use the following prefix or postfix to indicate variable types:

     m_, class member
     s_, static class member
     g_, global variables
     b, boolean variables (could be omitted for names like flgSplit)
     _t, defined types
     

Supplemental Rules

The following rules are collected through code review.

1. never use tab as indentation

   (they have already been mentioned in “Basic Rules”)
2. pay attention to the use of space

   (they have already been mentioned in “Basic Rules”)

   • wrong

     int * dat
     & dat
     if(...){
     

   • right

     int *dat
     &dat
     if (...) {
     

3. definition must be atomic

   • wrong:

     #define C    A + B
     

   • right:

     #define C    (A + B)
     

4. use magic numbers as less as possible