| Akinobu Mita | 3b9ed1a | 2006-03-26 01:39:13 -0800 | [diff] [blame^] | 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 | { |
| 13 | unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555); |
| 14 | res = (res & 0x33333333) + ((res >> 2) & 0x33333333); |
| 15 | res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F); |
| 16 | res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF); |
| 17 | return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF); |
| 18 | } |
| 19 | EXPORT_SYMBOL(hweight32); |
| 20 | |
| 21 | unsigned int hweight16(unsigned int w) |
| 22 | { |
| 23 | unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555); |
| 24 | res = (res & 0x3333) + ((res >> 2) & 0x3333); |
| 25 | res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F); |
| 26 | return (res & 0x00FF) + ((res >> 8) & 0x00FF); |
| 27 | } |
| 28 | EXPORT_SYMBOL(hweight16); |
| 29 | |
| 30 | unsigned int hweight8(unsigned int w) |
| 31 | { |
| 32 | unsigned int res = (w & 0x55) + ((w >> 1) & 0x55); |
| 33 | res = (res & 0x33) + ((res >> 2) & 0x33); |
| 34 | return (res & 0x0F) + ((res >> 4) & 0x0F); |
| 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 |
| 43 | u64 res; |
| 44 | res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul); |
| 45 | res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); |
| 46 | res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful); |
| 47 | res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul); |
| 48 | res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul); |
| 49 | return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul); |
| 50 | #else |
| 51 | #error BITS_PER_LONG not defined |
| 52 | #endif |
| 53 | } |
| 54 | EXPORT_SYMBOL(hweight64); |