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| author | Akinobu Mita <mita@miraclelinux.com> | 2006-03-26 11:39:12 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-26 18:57:11 +0200 |
| commit | 6d29ea23da033f46ac4ab359d46650a7f7474611 (patch) | |
| tree | 20403ba836b8e5e7ace71cae914bbc16d552a4bd | |
| parent | [PATCH] bitops: generic find_{next,first}{,_zero}_bit() (diff) | |
| download | linux-6d29ea23da033f46ac4ab359d46650a7f7474611.tar.xz linux-6d29ea23da033f46ac4ab359d46650a7f7474611.zip | |
[PATCH] bitops: generic sched_find_first_bit()
This patch introduces the C-language equivalent of the function: int
sched_find_first_bit(const unsigned long *b);
In include/asm-generic/bitops/sched.h
This code largely copied from: include/asm-powerpc/bitops.h
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | include/asm-generic/bitops/sched.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/sched.h b/include/asm-generic/bitops/sched.h new file mode 100644 index 000000000000..5ef93a4d009f --- /dev/null +++ b/include/asm-generic/bitops/sched.h @@ -0,0 +1,36 @@ +#ifndef _ASM_GENERIC_BITOPS_SCHED_H_ +#define _ASM_GENERIC_BITOPS_SCHED_H_ + +#include <linux/compiler.h> /* unlikely() */ +#include <asm/types.h> + +/* + * Every architecture must define this function. It's the fastest + * way of searching a 140-bit bitmap where the first 100 bits are + * unlikely to be set. It's guaranteed that at least one of the 140 + * bits is cleared. + */ +static inline int sched_find_first_bit(const unsigned long *b) +{ +#if BITS_PER_LONG == 64 + if (unlikely(b[0])) + return __ffs(b[0]); + if (unlikely(b[1])) + return __ffs(b[1]) + 64; + return __ffs(b[2]) + 128; +#elif BITS_PER_LONG == 32 + if (unlikely(b[0])) + return __ffs(b[0]); + if (unlikely(b[1])) + return __ffs(b[1]) + 32; + if (unlikely(b[2])) + return __ffs(b[2]) + 64; + if (b[3]) + return __ffs(b[3]) + 96; + return __ffs(b[4]) + 128; +#else +#error BITS_PER_LONG not defined +#endif +} + +#endif /* _ASM_GENERIC_BITOPS_SCHED_H_ */ |