1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_GENERIC_BITOPS_FLS64_H_
3 #define _ASM_GENERIC_BITOPS_FLS64_H_
4
5 #include <asm/types.h>
6
7 /**
8 * fls64 - find last set bit in a 64-bit word
9 * @x: the word to search
10 *
11 * This is defined in a similar way as the libc and compiler builtin
12 * ffsll, but returns the position of the most significant set bit.
13 *
14 * fls64(value) returns 0 if value is 0 or the position of the last
15 * set bit if value is nonzero. The last (most significant) bit is
16 * at position 64.
17 */
18 #if BITS_PER_LONG == 32
19 static __always_inline int fls64(__u64 x)
20 {
21 __u32 h = x >> 32;
22 if (h)
23 return fls(h) + 32;
24 return fls(x);
25 }
26 #elif BITS_PER_LONG == 64
27 static __always_inline int fls64(__u64 x)
28 {
29 if (x == 0)
30 return 0;
31 return __fls(x) + 1;
32 }
33 #else
34 #error BITS_PER_LONG not 32 or 64
35 #endif
36
37 #endif /* _ASM_GENERIC_BITOPS_FLS64_H_ */
38
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.