| 1 | #ifndef _ASM_GENERIC_BITOPS___FFS_H_ |
| 2 | #define _ASM_GENERIC_BITOPS___FFS_H_ |
| 3 | |
| 4 | #include <asm/types.h> |
| 5 | |
| 6 | /** |
| 7 | * __ffs - find first bit in word. |
| 8 | * @word: The word to search |
| 9 | * |
| 10 | * Undefined if no bit exists, so code should check against 0 first. |
| 11 | */ |
| 12 | static inline unsigned long __ffs(unsigned long word) |
| 13 | { |
| 14 | int num = 0; |
| 15 | |
| 16 | #if BITS_PER_LONG == 64 |
| 17 | if ((word & 0xffffffff) == 0) { |
| 18 | num += 32; |
| 19 | word >>= 32; |
| 20 | } |
| 21 | #endif |
| 22 | if ((word & 0xffff) == 0) { |
| 23 | num += 16; |
| 24 | word >>= 16; |
| 25 | } |
| 26 | if ((word & 0xff) == 0) { |
| 27 | num += 8; |
| 28 | word >>= 8; |
| 29 | } |
| 30 | if ((word & 0xf) == 0) { |
| 31 | num += 4; |
| 32 | word >>= 4; |
| 33 | } |
| 34 | if ((word & 0x3) == 0) { |
| 35 | num += 2; |
| 36 | word >>= 2; |
| 37 | } |
| 38 | if ((word & 0x1) == 0) |
| 39 | num += 1; |
| 40 | return num; |
| 41 | } |
| 42 | |
| 43 | #endif /* _ASM_GENERIC_BITOPS___FFS_H_ */ |