| Greg Kroah-Hartman | b244131 | 2017-11-01 15:07:57 +0100 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| Akinobu Mita | 136abb3 | 2006-03-26 01:39:09 -0800 | [diff] [blame] | 2 | #ifndef _ASM_GENERIC_BITOPS_FLS_H_ |
| 3 | #define _ASM_GENERIC_BITOPS_FLS_H_ |
| 4 | |
| 5 | /** |
| 6 | * fls - find last (most-significant) bit set |
| 7 | * @x: the word to search |
| 8 | * |
| 9 | * This is defined the same way as ffs. |
| 10 | * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. |
| 11 | */ |
| 12 | |
| Matthew Wilcox | 3fc2579 | 2019-01-03 15:26:41 -0800 | [diff] [blame] | 13 | static __always_inline int fls(unsigned int x) |
| Akinobu Mita | 136abb3 | 2006-03-26 01:39:09 -0800 | [diff] [blame] | 14 | { |
| 15 | int r = 32; |
| 16 | |
| 17 | if (!x) |
| 18 | return 0; |
| 19 | if (!(x & 0xffff0000u)) { |
| 20 | x <<= 16; |
| 21 | r -= 16; |
| 22 | } |
| 23 | if (!(x & 0xff000000u)) { |
| 24 | x <<= 8; |
| 25 | r -= 8; |
| 26 | } |
| 27 | if (!(x & 0xf0000000u)) { |
| 28 | x <<= 4; |
| 29 | r -= 4; |
| 30 | } |
| 31 | if (!(x & 0xc0000000u)) { |
| 32 | x <<= 2; |
| 33 | r -= 2; |
| 34 | } |
| 35 | if (!(x & 0x80000000u)) { |
| 36 | x <<= 1; |
| 37 | r -= 1; |
| 38 | } |
| 39 | return r; |
| 40 | } |
| 41 | |
| 42 | #endif /* _ASM_GENERIC_BITOPS_FLS_H_ */ |