message: operate more on values where possible
diff: @@ -417,14 +417,14 @@ fn mac3(acc: &mut [BigDigit], b: &[BigDigit], c: &[BigDigit]) {
  let r0 = &x0 * &y0;
  let r4 = &x2 * &y2;
  - let r1 = (&p + &x1) * (&q + &y1);
  + let r1 = (p + x1) * (q + y1);
  let r2 = &p2 * &q2;
  let r3 = ((p2 + x2)*2 - x0) * ((q2 + y2)*2 - y0);
  - let mut comp3: BigInt = (&r3 - &r1) / 3;
  - let mut comp1: BigInt = (&r1 - &r2) / 2;
  - let mut comp2: BigInt = &r2 - &r0;
  - comp3 = (&comp2 - &comp3)/2 + &r4*2;
  + let mut comp3: BigInt = (r3 - &r1) / 3;
  + let mut comp1: BigInt = (r1 - &r2) / 2;
  + let mut comp2: BigInt = r2 - &r0;
  + comp3 = (&comp2 - comp3)/2 + &r4*2;
  comp2 = comp2 + &comp1 - &r4;
  comp1 = comp1 - &comp3;
  