1#include "hweight.h"
2
3unsigned int hweight8(uint8_t w)
4{
5	unsigned int res = w - ((w >> 1) & 0x55);
6
7	res = (res & 0x33) + ((res >> 2) & 0x33);
8	return (res + (res >> 4)) & 0x0F;
9}
10
11unsigned int hweight32(uint32_t w)
12{
13	unsigned int res = w - ((w >> 1) & 0x55555555);
14
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
21unsigned int hweight64(uint64_t w)
22{
23#if BITS_PER_LONG == 32
24	return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
25#else
26	uint64_t res = w - ((w >> 1) & 0x5555555555555555ULL);
27	res = (res & 0x3333333333333333ULL) + ((res >> 2) & 0x3333333333333333ULL);
28	res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0FULL;
29	res = res + (res >> 8);
30	res = res + (res >> 16);
31	return (res + (res >> 32)) & 0x00000000000000FFULL;
32#endif
33}
34