1 #include "hweight.h" 2 hweight8(uint8_t w)3unsigned int hweight8(uint8_t w) 4 { 5 unsigned int res = w - ((w >> 1) & 0x55); 6 7 res = (res & 0x33) + ((res >> 2) & 0x33); 8 return (res + (res >> 4)) & 0x0F; 9 } 10 hweight32(uint32_t w)11unsigned int hweight32(uint32_t w) 12 { 13 unsigned int res = w - ((w >> 1) & 0x55555555); 14 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 hweight64(uint64_t w)21unsigned int hweight64(uint64_t w) 22 { 23 #if BITS_PER_LONG == 32 24 return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); 25 #else 26 uint64_t res = w - ((w >> 1) & 0x5555555555555555ULL); 27 res = (res & 0x3333333333333333ULL) + ((res >> 2) & 0x3333333333333333ULL); 28 res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0FULL; 29 res = res + (res >> 8); 30 res = res + (res >> 16); 31 return (res + (res >> 32)) & 0x00000000000000FFULL; 32 #endif 33 } 34