| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ |
| 3 | #define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ |
| 4 | |
| 5 | #include <asm/types.h> |
| 6 | #include <asm/bitsperlong.h> |
| 7 | |
| 8 | /** |
| 9 | * __ffs - find first bit in word. |
| 10 | * @word: The word to search |
| 11 | * |
| 12 | * Undefined if no bit exists, so code should check against 0 first. |
| 13 | */ |
| 14 | static __always_inline unsigned long __ffs(unsigned long word) |
| 15 | { |
| 16 | int num = 0; |
| 17 | |
| 18 | #if __BITS_PER_LONG == 64 |
| 19 | if ((word & 0xffffffff) == 0) { |
| 20 | num += 32; |
| 21 | word >>= 32; |
| 22 | } |
| 23 | #endif |
| 24 | if ((word & 0xffff) == 0) { |
| 25 | num += 16; |
| 26 | word >>= 16; |
| 27 | } |
| 28 | if ((word & 0xff) == 0) { |
| 29 | num += 8; |
| 30 | word >>= 8; |
| 31 | } |
| 32 | if ((word & 0xf) == 0) { |
| 33 | num += 4; |
| 34 | word >>= 4; |
| 35 | } |
| 36 | if ((word & 0x3) == 0) { |
| 37 | num += 2; |
| 38 | word >>= 2; |
| 39 | } |
| 40 | if ((word & 0x1) == 0) |
| 41 | num += 1; |
| 42 | return num; |
| 43 | } |
| 44 | |
| 45 | #endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ */ |