Re: [Discuss-gnuradio] Working with Tags

[Tom Rondeau]

On Wed, Dec 30, 2015 at 11:15 AM, <address@hidden> wrote:

I wrote a block that writes the rx_time tag and another block that reads it. After reading them for a 20 to thirty calls to the work function, it stops getting any. The amount it reads varies from run to run. Any ideas?

This code snippet is from the work function my block that writes the tag. The cerr statement continues to print to the console until I stop execution.

 

<code>

    VITA49_packet_info packet_info = p_packet->get_VITA49_packet_info();

    if (m_do_send_tags)

    {

      double timestamp_in_seconds =

          static_cast<double>(p_packet->get_integer_seconds()) +

          static_cast<double>(p_packet->get_fraction_seconds()) * 1e-12;

      const pmt::pmt_t timestamp = pmt::make_tuple(

          pmt::from_uint64(static_cast<long long>(floor(timestamp_in_seconds))),

          pmt::from_double(timestamp_in_seconds - floor(timestamp_in_seconds)));

      std::cerr << "SEND (" << d_id << ") "

                << " tag_offset=" << m_tag_offset

                << std::setprecision(std::numeric_limits<double>::digits10 + 1)

                << " timesamp_in_seconds=" << timestamp_in_seconds << std::endl;

      add_item_tag(0, m_tag_offset, TIME_KEY, timestamp, d_id);

</code>

How are you setting m_tag_offset?

 

This code snippet is from my work function in the block that reads the tag. The cerr statement stops printing after twenty to thirty times suggesting that it no longer sees the time tags. The rest of the work function continues to operate properly.

<code>

  static const pmt::pmt_t TIME_KEY = pmt::string_to_symbol("rx_time");

  std::vector<tag_t> tags;

  get_tags_in_range(

      tags, 0, nitems_read(0), nitems_read(0) + noutput_items);

  std::vector<tag_t>::iterator itr;

  size_t j = 0;

  for (itr = tags.begin(); itr != tags.end(); itr++, j++)

  {

    if (pmt::eq((*itr).key, TIME_KEY))

    {

      d_real_time_seconds =

          static_cast<double>(pmt::to_uint64(pmt::tuple_ref((*itr).value, 0))) +

          static_cast<double>(pmt::to_double(pmt::tuple_ref((*itr).value, 1)));

      std::cerr << "RECEIVE (" << d_id << ") " << j

                << " tag_offset=" << (*itr).offset

                << " noutput_items=" << noutput_items

                << std::setprecision(std::numeric_limits<double>::digits10 + 1)

                << " time_seconds=" << d_real_time_seconds << std::endl;

    }

  }

}

<code>

 

/\/\ark.

What does your flowgraph look like? Or is it just the tag producing block going straight in to the tag getter block?

Tom