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authorAkinobu Mita <mita@miraclelinux.com>2006-03-26 04:39:09 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-26 11:57:10 -0500
commit136abb32d6b4acf196425fb3968ebb368d84280e (patch)
tree48f0f127f204569b4484bac6ab014f8ca36f7477
parent176d8b0c2709e764d491e63a0c1b3a3e1459fcf8 (diff)
[PATCH] bitops: generic fls()
This patch introduces the C-language equivalent of the function: int fls(int x); In include/asm-generic/bitops/fls.h This code largely copied from: include/linux/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>
-rw-r--r--include/asm-generic/bitops/fls.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/fls.h b/include/asm-generic/bitops/fls.h
new file mode 100644
index 000000000000..850859bc5069
--- /dev/null
+++ b/include/asm-generic/bitops/fls.h
@@ -0,0 +1,41 @@
1#ifndef _ASM_GENERIC_BITOPS_FLS_H_
2#define _ASM_GENERIC_BITOPS_FLS_H_
3
4/**
5 * fls - find last (most-significant) bit set
6 * @x: the word to search
7 *
8 * This is defined the same way as ffs.
9 * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
10 */
11
12static inline int fls(int x)
13{
14 int r = 32;
15
16 if (!x)
17 return 0;
18 if (!(x & 0xffff0000u)) {
19 x <<= 16;
20 r -= 16;
21 }
22 if (!(x & 0xff000000u)) {
23 x <<= 8;
24 r -= 8;
25 }
26 if (!(x & 0xf0000000u)) {
27 x <<= 4;
28 r -= 4;
29 }
30 if (!(x & 0xc0000000u)) {
31 x <<= 2;
32 r -= 2;
33 }
34 if (!(x & 0x80000000u)) {
35 x <<= 1;
36 r -= 1;
37 }
38 return r;
39}
40
41#endif /* _ASM_GENERIC_BITOPS_FLS_H_ */