]>
Commit | Line | Data |
---|---|---|
3b9ed1a5 AM |
1 | #include <linux/module.h> |
2 | #include <asm/types.h> | |
3 | ||
4 | /** | |
5 | * hweightN - returns the hamming weight of a N-bit word | |
6 | * @x: the word to weigh | |
7 | * | |
8 | * The Hamming Weight of a number is the total number of bits set in it. | |
9 | */ | |
10 | ||
11 | unsigned int hweight32(unsigned int w) | |
12 | { | |
f9b41929 | 13 | unsigned int res = w - ((w >> 1) & 0x55555555); |
3b9ed1a5 | 14 | res = (res & 0x33333333) + ((res >> 2) & 0x33333333); |
f9b41929 AM |
15 | res = (res + (res >> 4)) & 0x0F0F0F0F; |
16 | res = res + (res >> 8); | |
17 | return (res + (res >> 16)) & 0x000000FF; | |
3b9ed1a5 AM |
18 | } |
19 | EXPORT_SYMBOL(hweight32); | |
20 | ||
21 | unsigned int hweight16(unsigned int w) | |
22 | { | |
f9b41929 | 23 | unsigned int res = w - ((w >> 1) & 0x5555); |
3b9ed1a5 | 24 | res = (res & 0x3333) + ((res >> 2) & 0x3333); |
f9b41929 AM |
25 | res = (res + (res >> 4)) & 0x0F0F; |
26 | return (res + (res >> 8)) & 0x00FF; | |
3b9ed1a5 AM |
27 | } |
28 | EXPORT_SYMBOL(hweight16); | |
29 | ||
30 | unsigned int hweight8(unsigned int w) | |
31 | { | |
f9b41929 | 32 | unsigned int res = w - ((w >> 1) & 0x55); |
3b9ed1a5 | 33 | res = (res & 0x33) + ((res >> 2) & 0x33); |
f9b41929 | 34 | return (res + (res >> 4)) & 0x0F; |
3b9ed1a5 AM |
35 | } |
36 | EXPORT_SYMBOL(hweight8); | |
37 | ||
38 | unsigned long hweight64(__u64 w) | |
39 | { | |
40 | #if BITS_PER_LONG == 32 | |
41 | return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); | |
42 | #elif BITS_PER_LONG == 64 | |
f9b41929 | 43 | __u64 res = w - ((w >> 1) & 0x5555555555555555ul); |
3b9ed1a5 | 44 | res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); |
f9b41929 AM |
45 | res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; |
46 | res = res + (res >> 8); | |
47 | res = res + (res >> 16); | |
48 | return (res + (res >> 32)) & 0x00000000000000FFul; | |
3b9ed1a5 AM |
49 | #else |
50 | #error BITS_PER_LONG not defined | |
51 | #endif | |
52 | } | |
53 | EXPORT_SYMBOL(hweight64); |