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1 | #include <linux/bitops.h> |
2 | |
3 | /** |
4 | * hweightN - returns the hamming weight of a N-bit word |
5 | * @x: the word to weigh |
6 | * |
7 | * The Hamming Weight of a number is the total number of bits set in it. |
8 | */ |
9 | |
10 | unsigned int hweight32(unsigned int w) |
11 | { |
12 | unsigned int res = w - ((w >> 1) & 0x55555555); |
13 | res = (res & 0x33333333) + ((res >> 2) & 0x33333333); |
14 | res = (res + (res >> 4)) & 0x0F0F0F0F; |
15 | res = res + (res >> 8); |
16 | return (res + (res >> 16)) & 0x000000FF; |
17 | } |
18 | |
19 | unsigned long hweight64(__u64 w) |
20 | { |
21 | #if BITS_PER_LONG == 32 |
22 | return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); |
23 | #elif BITS_PER_LONG == 64 |
24 | __u64 res = w - ((w >> 1) & 0x5555555555555555ul); |
25 | res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); |
26 | res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; |
27 | res = res + (res >> 8); |
28 | res = res + (res >> 16); |
29 | return (res + (res >> 32)) & 0x00000000000000FFul; |
30 | #endif |
31 | } |
32 |
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