Re: [Discuss-gnuradio] forecast and general work function

[s . subrata105]

Thank you Marcus. I am trying to simulate a network with 2 transmitters and one 
receiver. The TX's transmit streams at random times and the RX receives the sum 
of the signals from both the TX's. The adder block however doesn't give any 
output when one of its input stream is empty (i.e. when both the inputs are not 
available at the same time) . That's why I'm trying to create an intermediate 
block for each TX that takes in an input and outputs zeros if the input is 
empty. This way the adder block would always have something to add. Thanks.

Subrata

> On Oct 28, 2015, at 17:36, Marcus Müller <address@hidden> wrote:
> 
> Hi Subrata,
> 
> while what you plan to do is possible if you build a block with a
> general_work method and a forecast. In fact, here the forecast
> implementation will probably be pretty crucial, but also be pretty
> simple -- just always require the same amount of samples from input0 as
> you're asked to produce output, and don't require anything from input1.
> 
> However, I'm pretty certain GNU Radio won't schedule your block as you
> want to (in fact, I just wrote a minimal test case to verify[1]).
> 
> My general recommendation would be to write a minimal block that takes a
> stream and converts it to messages, and passes those to
> gr-eventstream[2]. gr-eventstream has blocks to do exactly that: produce
> a zero-signal when there's no (message) input, produce the content of
> the message input otherwise; you could just take that output and add it
> to your input1, and be done :)
> 
> Best regards,
> Marcus
> 
> 
> [1] https://github.com/marcusmueller/gr-demo_assymetric_input clone, and
> run ./qa_prioritizer.py in the python/ folder
> [2] http://oshearesearch.com/tag/gr-eventstream/
>> On 28.10.2015 21:26, address@hidden wrote:
>> I am trying to create a block that has two input and one output. Its like a 
>> priority multiplexer; if input0 is empty then output = input1 else output = 
>> input0 ( input0 always has samples) its a stream based block. 
>> How do I declare the work function, because the number of samples needed 
>> from each input to produce noutput_items depends on whether input0 is empty. 
>> Any help in the general work function is also greatly appreciated.
>> 
>> Thanks
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> 
> 
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