presto-spi/src/main/java/io/prestosql/spi/type/UnscaledDecimal128Arithmetic.java/UnscaledDecimal128Arithmetic/toUnscaledString
class UnscaledDecimal128Arithmetic:    public static String toUnscaledString(Slice decimal)
    {
        if (isZero(decimal)) {
            return "0";
        }

        char[] buffer = new char[MAX_PRECISION + 1];
        int index = buffer.length;
        boolean negative = isNegative(decimal);
        decimal = unscaledDecimal(decimal);
        do {
            int remainder = divide(decimal, 10, decimal);
            buffer[--index] = (char) ('0' + remainder);
        }
        while (!isZero(decimal));

        if (negative) {
            buffer[--index] = '-';
        }

        return new String(buffer, index, buffer.length - index);
    }