| #include <linux/bitops.h> |
| * hweightN - returns the hamming weight of a N-bit word |
| * The Hamming Weight of a number is the total number of bits set in it. |
| unsigned int hweight32(unsigned int w) |
| unsigned int res = w - ((w >> 1) & 0x55555555); |
| res = (res & 0x33333333) + ((res >> 2) & 0x33333333); |
| res = (res + (res >> 4)) & 0x0F0F0F0F; |
| return (res + (res >> 16)) & 0x000000FF; |
| unsigned long hweight64(__u64 w) |
| return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); |
| #elif BITS_PER_LONG == 64 |
| __u64 res = w - ((w >> 1) & 0x5555555555555555ul); |
| res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); |
| res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; |
| return (res + (res >> 32)) & 0x00000000000000FFul; |