$NetBSD: STYLE,v 1.7 2002/09/06 13:18:51 gehenna Exp $

Style guide for NetBSD/alpha kernel files.

This file is meant to supplement the NetBSD KNF style guide (which covers
most of the rest of the system, and can be found in /usr/share/misc/style).


SECTIONS

       * INCLUDE FILES
       * RCS IDS
       * COMPILATION FLAGS
       * MACRO DEFINITIONS
       * BLOCKS AND EXPRESSIONS


INCLUDE FILES

(1) All option headers should be included first, and sorted, like:

#include "opt_dec_3000_300.h"
#include "opt_dec_3000_500.h"

(2) All C sources should include <sys/cdefs.h> as the first header to
be included after any option headers, with a line like:

#include <sys/cdefs.h>                  /* RCS ID & Copyright macro defns */


RCS IDS

(1) NetBSD RCS ID tags ($NetBSD: STYLE,v 1.7 2002/09/06 13:18:51 gehenna Exp $ tags) in C sources and headers should
appear at the top of the file in a single-line comment of the form

/*<space>$NetBSD: STYLE,v 1.7 2002/09/06 13:18:51 gehenna Exp $<space>*/

which differs from the normal NetBSD style, in that it uses spaces
rather than tabs to separate the tag from the comment start and end
delimiters.

(2) All C and assembler sources should include an RCS ID tag which can
be compiled into the binary, with a line like:

__KERNEL_RCSID(0, "$NetBSD: STYLE,v 1.7 2002/09/06 13:18:51 gehenna Exp $");

after the inclusion of cdefs.h.  Source files which include other source
files should change the number '0' to a different number, so that it
doesn't conflict with the RCS ID definitions in included sources.
Generation of these RCS IDs is disabled if the kernel option
NO_KERNEL_RCSIDS is defined.  (In some cases, picking the number to use
may not be so straightforward, but the rule above usually works.)


COMPILATION FLAGS

By default, NetBSD/alpha kernel files are compiled with the following gcc
warning flags:

       -Werror
       -Wall
       -Wstrict-prototypes
       -Wmissing-prototypes
       -Wno-format

NetBSD/alpha kernel code should compile cleanly with those flags.  At some
point in the future (when the nonstandard extensions have been removed
from the kernel printf() function), -Wformat will be re-enabled, so sources
should be able to compile with it enabled as well.


MACRO DEFINITIONS

(1) Macros which use C blocks (i.e. are of the form "{ ... expressions
.. }") should always be defined like:

#define MACRO(arg1, arg2, argN)                                 \
do {                                                            \
       ...                                                     \
       expressions                                             \
       ...                                                     \
} while (0)

so that they behave like functions or macros which don't use blocks (e.g.
for the purpose of "if (foo) MACRO(); else ...").


BLOCKS AND EXPRESSIONS

(1) Surround blocks with { and } more often than is absolutely necessary.
For instance:

       if (foo)
               bar();

is acceptable, but:

       if (foo) {
               bar();
       }

is preferred.  (In contrast, NetBSD KNF says that no braces are to be
used for control statements with zero or one statements.)

(2) Use extra parentheses when it makes expressions clearer.  For instance,

       (foo == 10 && bar == 20)

is acceptable, but:

       ((foo == 10) && (bar == 20))

is preferred.  (In contrast, NetBSD KNF says to avoid using parentheses
except where necessary unless the expression is very confusing without
them.)