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de1e17b1 ACM |
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 | */ | |
12 | static __always_inline unsigned long __fls(unsigned long word) | |
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_ */ |