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1 #include <linux/bitops.h>
2 #include <asm/types.h>
3 
4 /**
5  * hweightN - returns the hamming weight of a N-bit word
6  * @x: the word to weigh
7  *
8  * The Hamming Weight of a number is the total number of bits set in it.
9  */
10 
__sw_hweight32(unsigned int w)11 unsigned int __sw_hweight32(unsigned int w)
12 {
13 #ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
14 	w -= (w >> 1) & 0x55555555;
15 	w =  (w & 0x33333333) + ((w >> 2) & 0x33333333);
16 	w =  (w + (w >> 4)) & 0x0f0f0f0f;
17 	return (w * 0x01010101) >> 24;
18 #else
19 	unsigned int res = w - ((w >> 1) & 0x55555555);
20 	res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
21 	res = (res + (res >> 4)) & 0x0F0F0F0F;
22 	res = res + (res >> 8);
23 	return (res + (res >> 16)) & 0x000000FF;
24 #endif
25 }
26 
__sw_hweight16(unsigned int w)27 unsigned int __sw_hweight16(unsigned int w)
28 {
29 	unsigned int res = w - ((w >> 1) & 0x5555);
30 	res = (res & 0x3333) + ((res >> 2) & 0x3333);
31 	res = (res + (res >> 4)) & 0x0F0F;
32 	return (res + (res >> 8)) & 0x00FF;
33 }
34 
__sw_hweight8(unsigned int w)35 unsigned int __sw_hweight8(unsigned int w)
36 {
37 	unsigned int res = w - ((w >> 1) & 0x55);
38 	res = (res & 0x33) + ((res >> 2) & 0x33);
39 	return (res + (res >> 4)) & 0x0F;
40 }
41 
__sw_hweight64(__u64 w)42 unsigned long __sw_hweight64(__u64 w)
43 {
44 #if BITS_PER_LONG == 32
45 	return __sw_hweight32((unsigned int)(w >> 32)) +
46 	       __sw_hweight32((unsigned int)w);
47 #elif BITS_PER_LONG == 64
48 #ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
49 	w -= (w >> 1) & 0x5555555555555555ul;
50 	w =  (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
51 	w =  (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
52 	return (w * 0x0101010101010101ul) >> 56;
53 #else
54 	__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
55 	res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
56 	res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
57 	res = res + (res >> 8);
58 	res = res + (res >> 16);
59 	return (res + (res >> 32)) & 0x00000000000000FFul;
60 #endif
61 #endif
62 }
63