| Akinobu Mita | 136abb3 | 2006-03-26 01:39:09 -0800 | [diff] [blame] | 1 | #ifndef _ASM_GENERIC_BITOPS_FLS_H_ |
| 2 | #define _ASM_GENERIC_BITOPS_FLS_H_ |
| 3 | |
| 4 | /** |
| 5 | * fls - find last (most-significant) bit set |
| 6 | * @x: the word to search |
| 7 | * |
| 8 | * This is defined the same way as ffs. |
| 9 | * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. |
| 10 | */ |
| 11 | |
| Andi Kleen | c839994 | 2009-01-12 23:01:15 +0100 | [diff] [blame] | 12 | static __always_inline int fls(int x) |
| Akinobu Mita | 136abb3 | 2006-03-26 01:39:09 -0800 | [diff] [blame] | 13 | { |
| 14 | int r = 32; |
| 15 | |
| 16 | if (!x) |
| 17 | return 0; |
| 18 | if (!(x & 0xffff0000u)) { |
| 19 | x <<= 16; |
| 20 | r -= 16; |
| 21 | } |
| 22 | if (!(x & 0xff000000u)) { |
| 23 | x <<= 8; |
| 24 | r -= 8; |
| 25 | } |
| 26 | if (!(x & 0xf0000000u)) { |
| 27 | x <<= 4; |
| 28 | r -= 4; |
| 29 | } |
| 30 | if (!(x & 0xc0000000u)) { |
| 31 | x <<= 2; |
| 32 | r -= 2; |
| 33 | } |
| 34 | if (!(x & 0x80000000u)) { |
| 35 | x <<= 1; |
| 36 | r -= 1; |
| 37 | } |
| 38 | return r; |
| 39 | } |
| 40 | |
| 41 | #endif /* _ASM_GENERIC_BITOPS_FLS_H_ */ |