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