ATLAS coding style

ATLAS attempts to use a unified coding style. Older codes may not adhere to it strictly (especially in function prototyping and single-line ifs), but all new codes should do so.

• Strict ANSI/ISO 9899-1990 C conformance is required
  • Must use /* */, not //
• Lines are at most 80 characters in length
• No tabs should be used in the file, only spaces
  

  $\rightarrow$

  in vim can use :set expandtab

• Indentation is always 3 characters, and the braces should line up, as in:
  

        for (i=0; i < N; i++)
        {
           for (j=0; j < N; j++)
              statement;
        }
  

  All braces are lined up this way (eg., ifs, functions & loops).
• Multiline function calls have arguments indented to the opening paren:
  

                 error = function_call(arg1, arg2, arg3,
                                       arg4, ar5);
  

• If bodies are always on a separate line from if, so you want:
  

            if (cond)
               statement;
  

  
  rather than:
  

            if (cond) statement;
  

• Comments are either to the right of a line if there is room, or on lines preceeding the commented code if not, using a style like:
  

  /*
   *       This comment describes what is going on the below loop body
   *       and if conditional
   */
           if (cond)
           {
           }
  /*
   *       Comment describing else body
   */
           else
           {
           }
  

  
  Note that the comment text is lined up with the code it comments.
• Occasionally you need a superblock of comments, that describes a whole region of code (eg, multiple if/else blocks). This is done as:
  

  /*
   * ======================================================================
   * Here is a comment describing the total operation of multiple blocks of
   * code which are all individually commented in the above manner
   * ======================================================================
   */
  
     for ()
     {
        if (cond)
        ....
        else if
        ...
     }
  

• Functions prologues are commented like this:

  int my_func
  (
     int iparm,           /* comment describing this parameter */
     void *vp,            /* comment describing this paraemter */
     ...
  )
  /*
   * This mandatory block of comments placed between the func declaration and
   * the opening brace describes what the function does.  If the function
   * returns a value, this block of comments end with line(s) describing the
   * the return value, of the form:
   * RETURNS: 0 on success, non-zero error message otherwise
   *          second line describing return value
   */
  {
  }
  

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