| Alexander van Heukelum | 7d9dff2 | 2008-03-15 18:30:57 +0100 | [diff] [blame] | 1 | #ifndef _ASM_GENERIC_BITOPS___FLS_H_ |
| 2 | #define _ASM_GENERIC_BITOPS___FLS_H_ |
| 3 | |
| 4 | #include <asm/types.h> |
| 5 | |
| 6 | /** |
| 7 | * __fls - find last (most-significant) set bit in a long word |
| 8 | * @word: the word to search |
| 9 | * |
| 10 | * Undefined if no set bit exists, so code should check against 0 first. |
| 11 | */ |
| Andi Kleen | c8399943 | 2009-01-12 23:01:15 +0100 | [diff] [blame] | 12 | static __always_inline unsigned long __fls(unsigned long word) |
| Alexander van Heukelum | 7d9dff2 | 2008-03-15 18:30:57 +0100 | [diff] [blame] | 13 | { |
| 14 | int num = BITS_PER_LONG - 1; |
| 15 | |
| 16 | #if BITS_PER_LONG == 64 |
| 17 | if (!(word & (~0ul << 32))) { |
| 18 | num -= 32; |
| 19 | word <<= 32; |
| 20 | } |
| 21 | #endif |
| 22 | if (!(word & (~0ul << (BITS_PER_LONG-16)))) { |
| 23 | num -= 16; |
| 24 | word <<= 16; |
| 25 | } |
| 26 | if (!(word & (~0ul << (BITS_PER_LONG-8)))) { |
| 27 | num -= 8; |
| 28 | word <<= 8; |
| 29 | } |
| 30 | if (!(word & (~0ul << (BITS_PER_LONG-4)))) { |
| 31 | num -= 4; |
| 32 | word <<= 4; |
| 33 | } |
| 34 | if (!(word & (~0ul << (BITS_PER_LONG-2)))) { |
| 35 | num -= 2; |
| 36 | word <<= 2; |
| 37 | } |
| 38 | if (!(word & (~0ul << (BITS_PER_LONG-1)))) |
| 39 | num -= 1; |
| 40 | return num; |
| 41 | } |
| 42 | |
| 43 | #endif /* _ASM_GENERIC_BITOPS___FLS_H_ */ |