1#include <linux/module.h> 2#include <asm/types.h> 3#include <asm/bitops.h> 4 5/** 6 * hweightN - returns the hamming weight of a N-bit word 7 * @x: the word to weigh 8 * 9 * The Hamming Weight of a number is the total number of bits set in it. 10 */ 11 12unsigned int hweight32(unsigned int w) 13{ 14 unsigned int res = w - ((w >> 1) & 0x55555555); 15 res = (res & 0x33333333) + ((res >> 2) & 0x33333333); 16 res = (res + (res >> 4)) & 0x0F0F0F0F; 17 res = res + (res >> 8); 18 return (res + (res >> 16)) & 0x000000FF; 19} 20EXPORT_SYMBOL(hweight32); 21 22unsigned int hweight16(unsigned int w) 23{ 24 unsigned int res = w - ((w >> 1) & 0x5555); 25 res = (res & 0x3333) + ((res >> 2) & 0x3333); 26 res = (res + (res >> 4)) & 0x0F0F; 27 return (res + (res >> 8)) & 0x00FF; 28} 29EXPORT_SYMBOL(hweight16); 30 31unsigned int hweight8(unsigned int w) 32{ 33 unsigned int res = w - ((w >> 1) & 0x55); 34 res = (res & 0x33) + ((res >> 2) & 0x33); 35 return (res + (res >> 4)) & 0x0F; 36} 37EXPORT_SYMBOL(hweight8); 38 39unsigned long hweight64(__u64 w) 40{ 41#if BITS_PER_LONG == 32 42 return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); 43#elif BITS_PER_LONG == 64 44#ifdef ARCH_HAS_FAST_MULTIPLIER 45 w -= (w >> 1) & 0x5555555555555555ul; 46 w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul); 47 w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful; 48 return (w * 0x0101010101010101ul) >> 56; 49#else 50 __u64 res = w - ((w >> 1) & 0x5555555555555555ul); 51 res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); 52 res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; 53 res = res + (res >> 8); 54 res = res + (res >> 16); 55 return (res + (res >> 32)) & 0x00000000000000FFul; 56#endif 57#endif 58} 59EXPORT_SYMBOL(hweight64); 60