[linuxsh-shmedia-dev] Re: [parisc-linux] [patch 12/44] generic sched_find_first_bit()

[Grant G. <gru...@pa...>]

On Wed, Feb 01, 2006 at 06:02:36PM +0900, Akinobu Mita wrote:
> This patch introduces the C-language equivalent of the function:
> int sched_find_first_bit(const unsigned long *b);

Akinobu, would you prefer this is a slightly cleaner way?
(Not compile tested)

static inline int sched_find_first_bit(const unsigned long *b)
{
	if (unlikely(b[0]))
		return __ffs(b[0]);
	if (unlikely(b[1]))
		return __ffs(b[1]) + BITS_PER_LONG;
#if BITS_PER_LONG == 32
	if (unlikely(b[2]))
		return __ffs(b[2]) + 64;
	if (b[3])
		return __ffs(b[3]) + 96;
#endif
	return __ffs(b[128/BITS_PER_LONG]) + 128;
}

If BITS_PER_LONG isn't defined, the link step will fail and point
at a some unknown .o as the offender. But it's the responsibility
of the header file to make sure it's including the BITS_PER_LONG
definition, not the code that calls sched_find_first_bit().

hth,
grant