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Fabio Estevam77c85542015-11-05 12:43:23 -02001#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 */
12static __always_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_ */