3 unsigned int hweight8(uint8_t w)
5 unsigned int res = w - ((w >> 1) & 0x55);
7 res = (res & 0x33) + ((res >> 2) & 0x33);
8 return (res + (res >> 4)) & 0x0F;
11 unsigned int hweight32(uint32_t w)
13 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;
21 unsigned int hweight64(uint64_t w)
23 #if BITS_PER_LONG == 32
24 return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
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;