$NetBSD: STYLE,v 1.7 2002/09/06 13:18:43 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 13:18:43 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 13:18:43 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 13:18:43 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.)