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