blob: 360556a7803d4dae582b39edec3e91bb78ac7749 [file] [log] [blame]
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -08001#include <linux/module.h>
2#include <asm/types.h>
Andi Kleen01366112006-09-26 10:52:38 +02003#include <asm/bitops.h>
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -08004
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{
Akinobu Mitaf9b41922006-03-26 01:40:00 -080014 unsigned int res = w - ((w >> 1) & 0x55555555);
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080015 res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
Akinobu Mitaf9b41922006-03-26 01:40:00 -080016 res = (res + (res >> 4)) & 0x0F0F0F0F;
17 res = res + (res >> 8);
18 return (res + (res >> 16)) & 0x000000FF;
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080019}
20EXPORT_SYMBOL(hweight32);
21
22unsigned int hweight16(unsigned int w)
23{
Akinobu Mitaf9b41922006-03-26 01:40:00 -080024 unsigned int res = w - ((w >> 1) & 0x5555);
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080025 res = (res & 0x3333) + ((res >> 2) & 0x3333);
Akinobu Mitaf9b41922006-03-26 01:40:00 -080026 res = (res + (res >> 4)) & 0x0F0F;
27 return (res + (res >> 8)) & 0x00FF;
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080028}
29EXPORT_SYMBOL(hweight16);
30
31unsigned int hweight8(unsigned int w)
32{
Akinobu Mitaf9b41922006-03-26 01:40:00 -080033 unsigned int res = w - ((w >> 1) & 0x55);
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080034 res = (res & 0x33) + ((res >> 2) & 0x33);
Akinobu Mitaf9b41922006-03-26 01:40:00 -080035 return (res + (res >> 4)) & 0x0F;
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080036}
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
Andi Kleen01366112006-09-26 10:52:38 +020044#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
Akinobu Mitaf9b41922006-03-26 01:40:00 -080050 __u64 res = w - ((w >> 1) & 0x5555555555555555ul);
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080051 res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
Akinobu Mitaf9b41922006-03-26 01:40:00 -080052 res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
53 res = res + (res >> 8);
54 res = res + (res >> 16);
55 return (res + (res >> 32)) & 0x00000000000000FFul;
Andi Kleen01366112006-09-26 10:52:38 +020056#endif
Akinobu Mita3b9ed1a2006-03-26 01:39:13 -080057#endif
58}
59EXPORT_SYMBOL(hweight64);