static int lo0bits(ULong *y)
{
	int k;
	ULong x = *y;

	if (x & 7) {
		if (x & 1) {
			return 0;
		}
		if (x & 2) {
			*y = x >> 1;
			return 1;
		}
		*y = x >> 2;
		return 2;
	}
	k = 0;
	if (!(x & 0xffff)) {
		k = 16;
		x >>= 16;
	}
	if (!(x & 0xff)) {
		k += 8;
		x >>= 8;
	}
	if (!(x & 0xf)) {
		k += 4;
		x >>= 4;
	}
	if (!(x & 0x3)) {
		k += 2;
		x >>= 2;
	}
	if (!(x & 1)) {
		k++;
		x >>= 1;
		if (!(x & 1)) {
			return 32;
		}
	}
	*y = x;
	return k;
}