diff options
author | Akinobu Mita <mita@miraclelinux.com> | 2006-03-26 04:39:08 -0500 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-26 11:57:10 -0500 |
commit | c1226a005ec400e966f4993dfcc0e99fd7baa6a1 (patch) | |
tree | 7c69ee952fae6209b7e760c1b7de83e2d9f05d25 /include/asm-generic/bitops/__ffs.h | |
parent | 4117b02132d1cf96a3e1c57148e302c4801c974d (diff) |
[PATCH] bitops: generic __ffs()
This patch introduces the C-language equivalent of the function: unsigned long
__ffs(unsigned long word);
In include/asm-generic/bitops/__ffs.h
This code largely copied from: include/asm-sparc/bitops.h
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-generic/bitops/__ffs.h')
-rw-r--r-- | include/asm-generic/bitops/__ffs.h | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/__ffs.h b/include/asm-generic/bitops/__ffs.h new file mode 100644 index 000000000000..9a3274aecf83 --- /dev/null +++ b/include/asm-generic/bitops/__ffs.h | |||
@@ -0,0 +1,43 @@ | |||
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 | */ | ||
12 | static 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_ */ | ||