x := r.Uint64()
	lo1a, lo0 := bits.Mul32(uint32(x), n)
	hi, lo1b := bits.Mul32(uint32(x>>32), n)
	lo1, c := bits.Add32(lo1a, lo1b, 0)
	hi += c
	if lo1 == 0 && lo0 < uint32(n) {
		n64 := uint64(n)
		thresh := uint32(-n64 % n64)
		for lo1 == 0 && lo0 < thresh {
			x := r.Uint64()
			lo1a, lo0 = bits.Mul32(uint32(x), n)
			hi, lo1b = bits.Mul32(uint32(x>>32), n)
			lo1, c = bits.Add32(lo1a, lo1b, 0)
			hi += c
		}