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#include "hweight.h"
unsigned int hweight8(uint8_t w)
{
unsigned int res = w - ((w >> 1) & 0x55);
res = (res & 0x33) + ((res >> 2) & 0x33);
return (res + (res >> 4)) & 0x0F;
}
unsigned int hweight32(uint32_t w)
{
unsigned int res = w - ((w >> 1) & 0x55555555);
res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
res = (res + (res >> 4)) & 0x0F0F0F0F;
res = res + (res >> 8);
return (res + (res >> 16)) & 0x000000FF;
}
unsigned int hweight64(uint64_t w)
{
#if BITS_PER_LONG == 32
return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
#else
uint64_t res = w - ((w >> 1) & 0x5555555555555555ULL);
res = (res & 0x3333333333333333ULL) + ((res >> 2) & 0x3333333333333333ULL);
res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0FULL;
res = res + (res >> 8);
res = res + (res >> 16);
return (res + (res >> 32)) & 0x00000000000000FFULL;
#endif
}
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