|= n << 7 & 0b1000_0000 return r } func CenteredMod(x, m uint32) int32 { x = x % m if x > m/2 { return int32(x) - int32(m) } return int32(x) } func reduceModQ(x int32) uint32 { x %= q if x < 0 { return uint32(x + q) } return uint32(x) } func TestCenteredMod(t *testing.T) { for x := range uint32(q * 2) { got := CenteredMod(uint32(x), q) if reduceModQ(got) != (x % q) { t.Fatalf("CenteredMod(%d) = %d, which is not congruent to %d mod %d", x, got, x, q) } } for x := range uint32(q) { r, _ := fieldToMontgomery(x)...