1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_GENERIC_BITOPS___FLS_H_
3 #define _ASM_GENERIC_BITOPS___FLS_H_
4
5 #include <asm/types.h>
6
7 /**
8 * generic___fls - find last (most-significant) set bit in a long word
9 * @word: the word to search
10 *
11 * Undefined if no set bit exists, so code should check against 0 first.
12 */
13 static __always_inline unsigned int generic___fls(unsigned long word)
14 {
15 unsigned int num = BITS_PER_LONG - 1;
16
17 #if BITS_PER_LONG == 64
18 if (!(word & (~0ul << 32))) {
19 num -= 32;
20 word <<= 32;
21 }
22 #endif
23 if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
24 num -= 16;
25 word <<= 16;
26 }
27 if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
28 num -= 8;
29 word <<= 8;
30 }
31 if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
32 num -= 4;
33 word <<= 4;
34 }
35 if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
36 num -= 2;
37 word <<= 2;
38 }
39 if (!(word & (~0ul << (BITS_PER_LONG-1))))
40 num -= 1;
41 return num;
42 }
43
44 #ifndef __HAVE_ARCH___FLS
45 #define __fls(word) generic___fls(word)
46 #endif
47
48 #endif /* _ASM_GENERIC_BITOPS___FLS_H_ */
49
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