Function AddLargePositive

cpp/src/gandiva/precompiled/decimal_ops.cc:68–98

Both x_value and y_value must be >= 0

/// Both x_value and y_value must be >= 0
static BasicDecimal128 AddLargePositive(const BasicDecimalScalar128& x,
                                        const BasicDecimalScalar128& y,
                                        int32_t out_scale) {
  DCHECK_GE(x.value(), 0);
  DCHECK_GE(y.value(), 0);

  // separate out whole/fractions.
  BasicDecimal128 x_left, x_right, y_left, y_right;
  x.value().GetWholeAndFraction(x.scale(), &x_left, &x_right);
  y.value().GetWholeAndFraction(y.scale(), &y_left, &y_right);

  // Adjust fractional parts to higher scale.
  auto higher_scale = std::max(x.scale(), y.scale());
  auto x_right_scaled = CheckAndIncreaseScale(x_right, higher_scale - x.scale());
  auto y_right_scaled = CheckAndIncreaseScale(y_right, higher_scale - y.scale());

  BasicDecimal128 right;
  BasicDecimal128 carry_to_left;
  auto multiplier = BasicDecimal128::GetScaleMultiplier(higher_scale);
  if (x_right_scaled >= multiplier - y_right_scaled) {
    right = x_right_scaled - (multiplier - y_right_scaled);
    carry_to_left = 1;
  } else {
    right = x_right_scaled + y_right_scaled;
    carry_to_left = 0;
  }
  right = CheckAndReduceScale(right, higher_scale - out_scale);

  auto left = x_left + y_left + carry_to_left;
  return (left * BasicDecimal128::GetScaleMultiplier(out_scale)) + right;
}

/// x_value and y_value cannot be 0, and one must be positive and the other negative.
static BasicDecimal128 AddLargeNegative(const BasicDecimalScalar128& x,