1 #include <linux/module.h>
2 #include <linux/bitops.h>
3 #include <asm/types.h>
4
5 /**
6 * hweightN - returns the hamming weight of a N-bit word
7 * @x: the word to weigh
8 *
9 * The Hamming Weight of a number is the total number of bits set in it.
10 */
11
12 unsigned int hweight32(unsigned int w)
13 {
14 unsigned int res = w - ((w >> 1) & 0x55555555);
15 res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
16 res = (res + (res >> 4)) & 0x0F0F0F0F;
17 res = res + (res >> 8);
18 return (res + (res >> 16)) & 0x000000FF;
19 }
20 EXPORT_SYMBOL(hweight32);
21
22 unsigned int hweight16(unsigned int w)
23 {
24 unsigned int res = w - ((w >> 1) & 0x5555);
25 res = (res & 0x3333) + ((res >> 2) & 0x3333);
26 res = (res + (res >> 4)) & 0x0F0F;
27 return (res + (res >> 8)) & 0x00FF;
28 }
29 EXPORT_SYMBOL(hweight16);
30
31 unsigned int hweight8(unsigned int w)
32 {
33 unsigned int res = w - ((w >> 1) & 0x55);
34 res = (res & 0x33) + ((res >> 2) & 0x33);
35 return (res + (res >> 4)) & 0x0F;
36 }
37 EXPORT_SYMBOL(hweight8);
38
39 unsigned long hweight64(__u64 w)
40 {
41 #if BITS_PER_LONG == 32
42 return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
43 #elif BITS_PER_LONG == 64
44 #ifdef ARCH_HAS_FAST_MULTIPLIER
45 w -= (w >> 1) & 0x5555555555555555ul;
46 w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
47 w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
48 return (w * 0x0101010101010101ul) >> 56;
49 #else
50 __u64 res = w - ((w >> 1) & 0x5555555555555555ul);
51 res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
52 res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
53 res = res + (res >> 8);
54 res = res + (res >> 16);
55 return (res + (res >> 32)) & 0x00000000000000FFul;
56 #endif
57 #endif
58 }
59 EXPORT_SYMBOL(hweight64);
60
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