Pepper kernel coding style

This document describes the coding style for the Pepper kernel. It is used as a guideline across all source files.

Indentation

Indentations should be 4 characters long.

Line length

Lines should not be more than 100 characters long.

Variables

Variables should be declared at most once per line.

Braces

Non-function statement blocks should have an opening brace last on the line, and a closing brace first. Exception is made for else, else if statements and the like:

if (something) {
    do_something();
} else if (something_else) {
    do_something_else();
}

Having no braces for a single statement structure is fine.

Functions should have their opening brace on a separate line, and the same goes for the closing brace:

void function()
{
    do_something();
}

Spaces

Use a space after if, switch, case, for, do, while keywords, but not for sizeof, typeof, alignof, __attribute__ and the like.

For pointers, the asterisk should always be placed adjacent to the type name, like char* str;.

Naming

Functions should be named with whole words, beginning with the corresponding name of the module in the kernel (the parent folder). Words should be spaced with underscores, like so:

serial_init(void* ptr, char* str, int foo);

Constants should be named in all caps, separated by underscores:

#define MAX_HEAP_SIZE 0x1000

Global variables need to have descriptive names. Local variables can be kept short (especially for loop counters).

Typedefs

Structures should not be typedef'd. However using typedef for an enumeration is fine.

Functions

Functions should be short, simple, and only do one thing.

Function prototypes should include parameter names and their data types.

Commenting

Comments should describe what a function does and why, not how it does it. The preferred way of commenting functions is the following:

/*
 * function_name - Function brief description
 * @arg1: Argument 1 description
 * @arg2: Argument 2 description
 *
 * A longer description can be featured here, explaining more
 * in detail what the function does and why it does it.
 */

Kernel messages

When printing kernel messages with the DEBUG macro, they should start with a capital letter.

Resources

Some of the elements here are inspired by the Linux kernel coding style.

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