ref: 32a1b47da6fe0e872c66d2721ff221ff1a5e8ba8
dir: /src/plan9/popcount.c/
#include "platform.h" int sl_popcount(unsigned int w) { w -= (w >> 1) & 0x55555555U; w = (w & 0x33333333U) + ((w >> 2) & 0x33333333U); w = (w + (w >> 4)) & 0x0F0F0F0FU; w = (w * 0x01010101U) >> 24; return w; }