1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_GENERIC_BITOPS_FLS_H_
3 #define _ASM_GENERIC_BITOPS_FLS_H_
4
5 /**
6 * generic_fls - find last (most-significant) bit set
7 * @x: the word to search
8 *
9 * This is defined the same way as ffs.
10 * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
11 */
12
13 static __always_inline int generic_fls(unsigned int x)
14 {
15 int r = 32;
16
17 if (!x)
18 return 0;
19 if (!(x & 0xffff0000u)) {
20 x <<= 16;
21 r -= 16;
22 }
23 if (!(x & 0xff000000u)) {
24 x <<= 8;
25 r -= 8;
26 }
27 if (!(x & 0xf0000000u)) {
28 x <<= 4;
29 r -= 4;
30 }
31 if (!(x & 0xc0000000u)) {
32 x <<= 2;
33 r -= 2;
34 }
35 if (!(x & 0x80000000u)) {
36 x <<= 1;
37 r -= 1;
38 }
39 return r;
40 }
41
42 #ifndef __HAVE_ARCH_FLS
43 #define fls(x) generic_fls(x)
44 #endif
45
46 #endif /* _ASM_GENERIC_BITOPS_FLS_H_ */
47
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