shithub: femtolisp

ref: 2e8caea3fb2dc18b3a1e5f51c62ca49c841d850e
dir: /popcount.c/

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#include "platform.h"

uint32_t
__builtin_popcount(uint32_t b)
{
	b = b - ((b>>1)&0x55555555);
	b = ((b>>2)&0x33333333) + (b&0x33333333);
	b = ((b>>4)+b)&0x0f0f0f0f;
	b += (b>>8);
	b += (b>>16);
	return b & 0x3f;
}