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Alexander van Heukelum7d9dff22008-03-15 18:30:57 +01001#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 */
12static 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_ */