CODING_STYLE

Coding Style for the Xen Test Framework
=======================================

The Xen Test Framework inherits its coding style from the Xen hypervisor.

Indentation
-----------

Indenting uses spaces, not tabs - in contrast to Linux.  An indent
level consists of four spaces.  Code within blocks is indented by one
extra indent level.  The enclosing braces of a block are indented the
same as the code _outside_ the block.  e.g.

void fun(void)
{
    /* One level of indent. */

    {
        /* A second level of indent. */
    }
}

White space
-----------

Space characters are used to spread out logical statements, such as in
the condition of an if or while.  Spaces are placed between the
keyword and the brackets surrounding the condition, between the
brackets and the condition itself, and around binary operators (except
the structure access operators, '.' and '->'). e.g.

if ( (wibble & wombat) == 42 )
{
    ...

There should be no trailing white space at the end of lines (including
after the opening /* of a comment block).

Line Length
-----------

Lines should be less than 80 characters in length.  Long lines should
be split at sensible places and the trailing portions indented.

User visible strings (e.g., printk() messages) should not be split so
they can searched for more easily.

Bracing
-------

Braces ('{' and '}') are usually placed on a line of their own, except
for the do/while loop.  This is unlike the Linux coding style and
unlike K&R.  do/while loops are an exception. e.g.:

if ( condition )
{
    /* Do stuff. */
}
else
{
    /* Other stuff. */
}

while ( condition )
{
    /* Do stuff. */
}

do {
    /* Do stuff. */
} while ( condition );

etc.

Braces should be omitted for blocks with a single statement. e.g.,

if ( condition )
    single_statement();

Comments
--------

Only C style /* ... */ comments are to be used.  C++ style // comments
should not be used.  Multi-word comments should begin with a capital
letter and end with a full stop.

Multi-line comment blocks should start and end with comment markers on
separate lines and each line should begin with a leading '*'.

/*
 * Example, multi-line comment block.
 *
 * Note beginning and end markers on separate lines and leading '*'.
 */

Emacs local variables
---------------------

A comment block containing local variables for emacs is permitted at
the end of files.  It should be:

/*
 * Local variables:
 * mode: C
 * c-file-style: "BSD"
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 */

Header files
------------

A microkernel will not make use of system libraries, and provide local
implementations of all required functionality.