diff options
Diffstat (limited to 'include/asm-generic/bitops/fls64.h')
| -rw-r--r-- | include/asm-generic/bitops/fls64.h | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/include/asm-generic/bitops/fls64.h b/include/asm-generic/bitops/fls64.h index 1b6b17ce242..b097cf8444e 100644 --- a/include/asm-generic/bitops/fls64.h +++ b/include/asm-generic/bitops/fls64.h @@ -3,12 +3,34 @@ #include <asm/types.h> -static inline int fls64(__u64 x) +/** + * fls64 - find last set bit in a 64-bit word + * @x: the word to search + * + * This is defined in a similar way as the libc and compiler builtin + * ffsll, but returns the position of the most significant set bit. + * + * fls64(value) returns 0 if value is 0 or the position of the last + * set bit if value is nonzero. The last (most significant) bit is + * at position 64. + */ +#if BITS_PER_LONG == 32 +static __always_inline int fls64(__u64 x) { __u32 h = x >> 32; if (h) return fls(h) + 32; return fls(x); } +#elif BITS_PER_LONG == 64 +static __always_inline int fls64(__u64 x) +{ + if (x == 0) + return 0; + return __fls(x) + 1; +} +#else +#error BITS_PER_LONG not 32 or 64 +#endif #endif /* _ASM_GENERIC_BITOPS_FLS64_H_ */ |