[Discuss-gnuradio] Packet-based communication & underrun / Possible solution?

[Mattia Rizzi]

I want a gnu radio application that send packets (messages) in AIR when pressing ENTER with USRP. Since i don't want any underun on USRP side, i need a block that send zero-filled packets when there's no data to send.
I solved it with a modify of message_source block.
Instead of call delete->head() and wait for a message, i check if there's a new message to send with empty_p(). If there isn't, then zero-fill the data (to the USRP)

The code
    //my code
     if (d_msgq->empty_p())
      {
     memset (out, 0, noutput_items*d_itemsize);
    return noutput_items;
      }
      // end of my code

      d_msg = d_msgq->delete_head();  //blocking call      
      d_msg_offset = 0;

It's okay? There are other ways to do it better? Thank you.