diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/bitops.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 387a81813..e14e6c7b1 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -38,6 +38,43 @@ static inline int generic_ffs(int x) return r; } +/** + * fls - find last (most-significant) bit set + * @x: the word to search + * + * This is defined the same way as ffs. + * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. + */ +static inline int generic_fls(int x) +{ + int r = 32; + + if (!x) + return 0; + if (!(x & 0xffff0000u)) { + x <<= 16; + r -= 16; + } + if (!(x & 0xff000000u)) { + x <<= 8; + r -= 8; + } + if (!(x & 0xf0000000u)) { + x <<= 4; + r -= 4; + } + if (!(x & 0xc0000000u)) { + x <<= 2; + r -= 2; + } + if (!(x & 0x80000000u)) { + x <<= 1; + r -= 1; + } + return r; +} + + /* * hweightN: returns the hamming weight (i.e. the number * of bits set) of a N-bit word @@ -82,6 +119,14 @@ static inline unsigned int generic_hweight8(unsigned int w) # define __clear_bit generic_clear_bit #endif +#ifndef ffs +# define ffs generic_ffs +#endif + +#ifndef fls +# define fls generic_fls +#endif + /** * __set_bit - Set a bit in memory * @nr: the bit to set |