Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6
[linux-2.6-block.git] / lib / hweight.c
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3b9ed1a5 1#include <linux/module.h>
1977f032 2#include <linux/bitops.h>
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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
12unsigned int hweight32(unsigned int w)
13{
f9b41929 14 unsigned int res = w - ((w >> 1) & 0x55555555);
3b9ed1a5 15 res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
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16 res = (res + (res >> 4)) & 0x0F0F0F0F;
17 res = res + (res >> 8);
18 return (res + (res >> 16)) & 0x000000FF;
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19}
20EXPORT_SYMBOL(hweight32);
21
22unsigned int hweight16(unsigned int w)
23{
f9b41929 24 unsigned int res = w - ((w >> 1) & 0x5555);
3b9ed1a5 25 res = (res & 0x3333) + ((res >> 2) & 0x3333);
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26 res = (res + (res >> 4)) & 0x0F0F;
27 return (res + (res >> 8)) & 0x00FF;
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28}
29EXPORT_SYMBOL(hweight16);
30
31unsigned int hweight8(unsigned int w)
32{
f9b41929 33 unsigned int res = w - ((w >> 1) & 0x55);
3b9ed1a5 34 res = (res & 0x33) + ((res >> 2) & 0x33);
f9b41929 35 return (res + (res >> 4)) & 0x0F;
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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
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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
f9b41929 50 __u64 res = w - ((w >> 1) & 0x5555555555555555ul);
3b9ed1a5 51 res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
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52 res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
53 res = res + (res >> 8);
54 res = res + (res >> 16);
55 return (res + (res >> 32)) & 0x00000000000000FFul;
0136611c 56#endif
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57#endif
58}
59EXPORT_SYMBOL(hweight64);