xref: /OK3568_Linux_fs/u-boot/arch/nios2/include/asm/bitops/ffs.h (revision 4882a59341e53eb6f0b4789bf948001014eff981) 
1*4882a593Smuzhiyun #ifndef _ASM_GENERIC_BITOPS_FFS_H_
2*4882a593Smuzhiyun #define _ASM_GENERIC_BITOPS_FFS_H_
3*4882a593Smuzhiyun 
4*4882a593Smuzhiyun /**
5*4882a593Smuzhiyun  * ffs - find first bit set
6*4882a593Smuzhiyun  * @x: the word to search
7*4882a593Smuzhiyun  *
8*4882a593Smuzhiyun  * This is defined the same way as
9*4882a593Smuzhiyun  * the libc and compiler builtin ffs routines, therefore
10*4882a593Smuzhiyun  * differs in spirit from the above ffz (man ffs).
11*4882a593Smuzhiyun  */
ffs(int x)12*4882a593Smuzhiyun static inline int ffs(int x)
13*4882a593Smuzhiyun {
14*4882a593Smuzhiyun 	int r = 1;
15*4882a593Smuzhiyun 
16*4882a593Smuzhiyun 	if (!x)
17*4882a593Smuzhiyun 		return 0;
18*4882a593Smuzhiyun 	if (!(x & 0xffff)) {
19*4882a593Smuzhiyun 		x >>= 16;
20*4882a593Smuzhiyun 		r += 16;
21*4882a593Smuzhiyun 	}
22*4882a593Smuzhiyun 	if (!(x & 0xff)) {
23*4882a593Smuzhiyun 		x >>= 8;
24*4882a593Smuzhiyun 		r += 8;
25*4882a593Smuzhiyun 	}
26*4882a593Smuzhiyun 	if (!(x & 0xf)) {
27*4882a593Smuzhiyun 		x >>= 4;
28*4882a593Smuzhiyun 		r += 4;
29*4882a593Smuzhiyun 	}
30*4882a593Smuzhiyun 	if (!(x & 3)) {
31*4882a593Smuzhiyun 		x >>= 2;
32*4882a593Smuzhiyun 		r += 2;
33*4882a593Smuzhiyun 	}
34*4882a593Smuzhiyun 	if (!(x & 1)) {
35*4882a593Smuzhiyun 		x >>= 1;
36*4882a593Smuzhiyun 		r += 1;
37*4882a593Smuzhiyun 	}
38*4882a593Smuzhiyun 	return r;
39*4882a593Smuzhiyun }
40*4882a593Smuzhiyun 
41*4882a593Smuzhiyun #endif /* _ASM_GENERIC_BITOPS_FFS_H_ */
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