Re: [Discuss-gnuradio] how does Packet Header Generator module handle tags

[hutiantian]

Hi Marcus,
What's the "non-length tags" mean?  the "length tags" you mentioned is 
that input  parameter, right? I only find this one tags.
When I remove  'set_tag_propagation_policy(TPP_DONT)', this module seems 
still works fine. Why should we need set this flag in this module?

Thanks
Tiankun

于 2014年07月20日 22:54, Marcus Müller 写道:
> Hi Tiankun,
>
> On 20.07.2014 15:50, hutiantian wrote:
> > Hi Marcus,
> > My tx_ofdm.py is gen by tx_ofdm.grc, there are a
> > 'packet_headergenerator_bb' module in it. This module use
> > 'set_tag_propagation_policy(TPP_DONT)' to handle tags by itself.
> Ah ok!
> > I didn't find any code has touch tags in this module, but when I
> > connect it to Tag Debug module, I can find the tags output.
> This is indeed strange. However, packet_headergenerator_bb is a subclass
> of tagged_stream_block [1].
>
> > In my opinion, if one module use
> > 'set_tag_propagation_policy(TPP_DONT)', and it does not handle it,
> > tags will not pass down.
> That's generally correct, but there's the tagged stream block exception:
> [1], "A note on tag propagation" tells us that one most of the time
> would use TPP_DONT to handle all non-length tags, whilst length tags are
> always passed forward.
>
> Hope that helped!
>
> Greetings,
> Marcus
>
>
> [1] http://gnuradio.org/doc/doxygen/page_tagged_stream_blocks.html
> > Thanks
> > Tiankun
> >
> > 于 2014年07月20日 21:15, Marcus Müller 写道:
> > > Hi Tiankun,
> > >
> > > what's your GNU Radio version [1]? Where did you find that tx_ofdm.py?
> > > There is no tx_ofdm.py in my GNU Radio source tree (in none of v3.7.4,
> > > v3.6.5 or v3.4.2). There is a tx_ofdm.grc, which can be used to generate
> > > a tx_ofdm.py, but that does not (and shouldn't) contain a
> > > "set_tag_propagation_policy" line.
> > >
> > > Greetings,
> > > Marcus
> > >
> > > [1] you can find out by running "gnuradio-config-info -v"
> > > On 20.07.2014 14:54, Tiankun Hu wrote:
> > > > Hi Experts,
> > > > I was reading tx_ofdm.py. I found this module use
> > > > 'set_tag_propagation_policy(TPP_DONT)' to handle tags by itself, but I
> > > > cann't find the code that used to handle tag in this module.
> > > > I knew this module will call 'packet_header_ofdm.header_formatter()'
> > > > and
> > > > 'packet_header_default.header_formatter()', but I also cann't find the
> > > > handle tag code in these functions.
> > > > Anyone can help me figure out where does this module process tags?
> > > >
> > > > Thanks
> > > > Tiankun
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > Discuss-gnuradio mailing list
> > > > address@hidden
> > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > >
> > >
> > >
> > > _______________________________________________
> > > Discuss-gnuradio mailing list
> > > address@hidden
> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio