presto-spi/src/main/java/io/prestosql/spi/type/UnscaledDecimal128Arithmetic.java/UnscaledDecimal128Arithmetic/unpackUnsignedLong
class UnscaledDecimal128Arithmetic:    private static long unpackUnsignedLong(long value)
    {
        return value & ~SIGN_LONG_MASK;
    }