presto-spi/src/main/java/io/prestosql/spi/type/UnscaledDecimal128Arithmetic.java/UnscaledDecimal128Arithmetic/addUnsignedMultiPrecision
class UnscaledDecimal128Arithmetic:    private static void addUnsignedMultiPrecision(int[] left, int leftOffset, int[] right, int length)
    {
        int leftIndex = leftOffset - length;
        int carry = 0;
        for (int rightIndex = 0; rightIndex < length; rightIndex++, leftIndex++) {
            long accumulator = toUnsignedLong(left[leftIndex]) + toUnsignedLong(right[rightIndex]) + toUnsignedLong(carry);
            left[leftIndex] = lowInt(accumulator);
            carry = highInt(accumulator);
        }
        left[leftIndex] += carry;
    }