1#include <linux/module.h>
2#include <asm/types.h>
3#include <asm/bitops.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
12unsigned 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}
20EXPORT_SYMBOL(hweight32);
21
22unsigned 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}
29EXPORT_SYMBOL(hweight16);
30
31unsigned 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}
37EXPORT_SYMBOL(hweight8);
38
39unsigned 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}
59EXPORT_SYMBOL(hweight64);
60