Re: [Discuss-gnuradio] Problem with messages and msg_queue

[Trond Danielsen]

2007/5/10, Eric Blossom <address@hidden>:
> On Wed, May 09, 2007 at 11:14:43PM +0200, Trond Danielsen wrote:
> > 2007/5/9, Eric Blossom <address@hidden>:
> > >On Wed, May 09, 2007 at 08:12:05PM +0200, Trond Danielsen wrote:
> > >> Hi everyone,
> > >>
> > >> I've got a problem with messages and message queues. The problem is
> > >> simply that I just cannot figure out how to use them. I tried the
> > >> simple program that is attached to this email (test.py), and the
> > >> result is in test.log. If anybody has the time to take a quick look at
> > >> the code and point me in the right direction, I would be very
> > >> thankful!
> > >>
> > >> Regards,
> > >>
> > >> --
> > >> Trond Danielsen
> > >
> > >
> > >This looks correct, and in fact you are receiving a payload that's 800
> > >bytes long (== 200 * sizeof(float)), so everything looks good.
> > >
> > >In reality, you'd want to do something with the payload:
> > >
> > >  payload = msg.to_string()  # return payload as an python string
> > >
> > >  foo = struct.unpack(format, payload)
> > >
> > >See gnuradio-core/src/python/gnuradio/blksimpl/pkt.py for a real-life
> > >example.
> > >
> > >Eric
> >
> > Ok, I guess I misunderstood one thing: I assumed that gr.message_sink(
> > gr.sizeof_float, ...) would set the payload size for each packet to 4
> > bytes.
>
> No, that would kill our performance.
>
> Eric

Ok, I read from pkt.py that to finish a packet, I just append
gr.message(1) at the tail of the message queue, but is there a simple
way to do this if I just want to send packet of fixed size, where the
payload comes from a flow graph?
--
Trond Danielsen