presto-spi/src/main/java/io/prestosql/spi/type/UnscaledDecimal128Arithmetic.java/UnscaledDecimal128Arithmetic/packUnsigned
class UnscaledDecimal128Arithmetic:    private static void packUnsigned(int[] digits, Slice decimal)
    {
        if (digitsInIntegerBase(digits) > NUMBER_OF_INTS) {
            throwOverflowException();
        }
        if ((digits[3] & SIGN_INT_MASK) != 0) {
            throwOverflowException();
        }
        pack(decimal, digits[0], digits[1], digits[2], digits[3], false);
    }