public static void Reduce(uint[] xx, uint[] z) { ulong cc = Nat256.Mul33Add(PInv33, xx, 8, xx, 0, z, 0); uint c = Nat256.Mul33DWordAdd(PInv33, cc, z, 0); Debug.Assert(c == 0 || c == 1); if (c != 0 || (z[7] == P7 && Nat256.Gte(z, P))) { Nat.Add33To(8, PInv33, z); } }