private final void register (SelectableChannel handle_, int ops, boolean negate)
    {
        PollSet pollset = fd_table.get(handle_);
        
        if (negate) 
            pollset.ops = pollset.ops &~ ops;
        else
            pollset.ops = pollset.ops | ops;
        
        if (pollset.key != null)
            pollset.key.interestOps(pollset.ops);
        else
            retired = true;
    }