presto-spi/src/main/java/io/prestosql/spi/type/UnscaledDecimal128Arithmetic.java/UnscaledDecimal128Arithmetic/combineInts
class UnscaledDecimal128Arithmetic:    private static long combineInts(int high, int low)
    {
        return (((long) high) << 32) | toUnsignedLong(low);
    }