SET, CLR, ISSET in types.h for _KERNEL builds
Yar Tikhiy
yar at comp.chem.msu.su
Wed Jun 28 09:42:36 UTC 2006
On Tue, Jun 27, 2006 at 01:58:17PM -0600, M. Warner Losh wrote:
> NetBSD recently added SET, CLR, ISSET to sys/types.h (only if _KERNEL
> is defined). I'd like to do something similar in FreeBSD. I see no
> reason to needless deviate from NetBSD here. One could make an
> argument for lots of different files, but at the end of the day does
> it really matter enough to justify having it be different than NetBSD?
>
> Here's my proposed diff, inline, for your consideration:
>
> Index: types.h
> ===================================================================
> RCS file: /home/ncvs/src/sys/sys/types.h,v
> retrieving revision 1.95
> diff -u -r1.95 types.h
> --- types.h 26 Nov 2005 12:42:35 -0000 1.95
> +++ types.h 27 Jun 2006 19:57:23 -0000
> @@ -294,6 +294,11 @@
>
> #define offsetof(type, field) __offsetof(type, field)
>
> +/* Macros to clear/set/test flags. */
> +#define SET(t, f) (t) |= (f)
> +#define CLR(t, f) (t) &= ~(f)
> +#define ISSET(t, f) ((t) & (f))
> +
> #endif /* !_KERNEL */
>
> /*
>
> NOTE: That /* !_KERNEL */ should have the '!' removed, but I didn't
> want to confuse things by doing that too.
>
> Comments?
I'd rather enclose the whole RHS of SET and CLR in parentheses.
It's still C; SET and CLR can be used in expressions and cause
precedence artefacts if not parenthesised.
--
Yar
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