1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
3#define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
4
5#include <asm/types.h>
6#include <asm/bitsperlong.h>
7
8/**
9 * __ffs - find first bit in word.
10 * @word: The word to search
11 *
12 * Undefined if no bit exists, so code should check against 0 first.
13 */
14static __always_inline unsigned long __ffs(unsigned long word)
15{
16	int num = 0;
17
18#if __BITS_PER_LONG == 64
19	if ((word & 0xffffffff) == 0) {
20		num += 32;
21		word >>= 32;
22	}
23#endif
24	if ((word & 0xffff) == 0) {
25		num += 16;
26		word >>= 16;
27	}
28	if ((word & 0xff) == 0) {
29		num += 8;
30		word >>= 8;
31	}
32	if ((word & 0xf) == 0) {
33		num += 4;
34		word >>= 4;
35	}
36	if ((word & 0x3) == 0) {
37		num += 2;
38		word >>= 2;
39	}
40	if ((word & 0x1) == 0)
41		num += 1;
42	return num;
43}
44
45#endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ */
46