Re: [Discuss-gnuradio] work function - how it fits in the big picture

[Eric Blossom]

On Thu, Apr 20, 2006 at 11:53:03AM -0400, Charles Swiger wrote:
> On Wed, 2006-04-19 at 17:41 -0700, Eric Blossom wrote:
> 
> > To  make the new code match the behavior of GrAtscTrellisEncoder
> > (which is what I think you're up to) you'll need to derive from
> > gr_sync_block and add this to your constructor:
> > 
> >   set_output_multiple(atsci_trellis_encoder::NCODERS);
> > 
> 
> Great - that seems to work.
> 
> > I also suggest adding the "paranoid check" that's at the bottom of
> > GrAtscTrellisEncoder if you haven't already.
> 
> That check is in the atsci_trellis_encoder.cc.
> 
> 
> 
> Ok - I'm going to spend time trying to understand all that. Putting
> the same thing in atsc_viterbi_decoder.cc compiles and runs and
> gets this further down the loopback:
> 
> sched: <gr_block atsc_viterbi_decoder (21)> is requesting more input
> data
>   than we can provide.
>   ninput_items_required = 12
>   max_possible_items_available = 7
>   If this is a filter, consider reducing the number of taps.
> 
> 
> It wants 12 4096-byte soft_data_segment, or 49152 bytes. Max
> available is 28672.
> 
> Well, one solution is to go into
> gnuradio-core/src/python/gnuradio/gr/flow_graph.py and change
> fixed_buffer_size to:
> 
>    self.fixed_buffer_size = 64*1024
> 
> from  32*1024
> 
> then make, make install.  Don't know if that can by dynamically 
> changed from the processing block.
> 
> Runs, few issues in the qa script then will update cvs.
> 
> --Chuck

Don't commit the change to flow_graph.py, I believe the right answer
is elsewhere.  Please do commit the atsc changes even though it fails
make check, and I'll use it to test and fix.  I think this is a symptom
of the same problem Marcus is seeing when trying to use large numbers
of taps in the FFT filters.

Eric