1 #include <linux/module.h> 2 #include <linux/bitops.h> 3 #include <asm/types.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 hweight32(unsigned int w)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 } 20 EXPORT_SYMBOL(hweight32); 21 hweight16(unsigned int w)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 } 29 EXPORT_SYMBOL(hweight16); 30 hweight8(unsigned int w)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 } 37 EXPORT_SYMBOL(hweight8); 38 hweight64(__u64 w)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 } 59 EXPORT_SYMBOL(hweight64); 60