1#include <linux/bitops.h>
2
3/**
4 * hweightN - returns the hamming weight of a N-bit word
5 * @x: the word to weigh
6 *
7 * The Hamming Weight of a number is the total number of bits set in it.
8 */
9
10unsigned int hweight32(unsigned int w)
11{
12	unsigned int res = w - ((w >> 1) & 0x55555555);
13	res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
14	res = (res + (res >> 4)) & 0x0F0F0F0F;
15	res = res + (res >> 8);
16	return (res + (res >> 16)) & 0x000000FF;
17}
18
19unsigned long hweight64(__u64 w)
20{
21#if BITS_PER_LONG == 32
22	return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
23#elif BITS_PER_LONG == 64
24	__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
25	res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
26	res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
27	res = res + (res >> 8);
28	res = res + (res >> 16);
29	return (res + (res >> 32)) & 0x00000000000000FFul;
30#endif
31}
32