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
