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c1226a00 AM |
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 | */ | |
c8399943 | 12 | static __always_inline unsigned long __ffs(unsigned long word) |
c1226a00 AM |
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_ */ |