presto-spi/src/main/java/io/prestosql/spi/type/UnscaledDecimal128Arithmetic.java/UnscaledDecimal128Arithmetic/setRawLong
class UnscaledDecimal128Arithmetic:    private static void setRawLong(Slice decimal, int index, long value)
    {
        unsafe.putLong(decimal.getBase(), decimal.getAddress() + SIZE_OF_LONG * index, value);
    }