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

[hutiantian]

Hi Martin,
What's the TSB tags? Does the tags have the different types? I think the 
tags just a pair of key-value.

Thanks
Tiankun

于 2014年07月21日 17:54, Martin Braun 写道:
> Before myths about tagged stream blocks start perpetuating the webs:
> TPP_DONT on a tagged stream blocks does the same as on any other type of
> block; however, TSB tags still get through.
>
> A closer inspection of packet_headergenerator_bb (either by reading the
> source code or the manual page
> (http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1packet__headergenerator__bb.html#details)
> reveals that the actual processing is done in a separate kernel, the
> header formatter object, which is user-defined. See
> packet_header_default for an example.
>
> M
>
> On 07/20/2014 04:54 PM, Marcus Müller wrote:
> > 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
> > > > >
> > > > >
> > > > >
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