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  */
__ffs(unsigned long word)14 static __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