Null source just sets all outputs to zero, so it’s equivalent to a constant
source with the scalar=0.
…
for(size_t n = 0; n < input_items.size(); n++) {
optr = (void*)output_items[n];
memset(optr, 0, noutput_items *
output_signature()->sizeof_stream_item(n));
}
…
I think this is some subtle issue with Stream Mux’s forecast function and how
it interacts with the scheduler knowing when to advance read pointers from the
upstream block. This is just a wild guess, though. Also, I’ve seen an upstream
block connect to two inputs of a Multiply block to create a squaring device,
and that seems to work just fine. But in Stream Mux’s case, it’s only copying
from one input at a time.
Sean
From: discuss-gnuradio-bounces+sean.nowlan=gtri.gatech....@gnu.org
[mailto:discuss-gnuradio-bounces+sean.nowlan=gtri.gatech....@gnu.org] On Behalf
Of Jeon
Sent: Wednesday, July 08, 2015 10:46 PM
To: Discuss GNU Radio mailing list
Subject: Re: [Discuss-gnuradio] Flowgraph locking up with Stream Mux
whileni didnt look into null source block code,
but the basic behavior of null source block is,
it outputs nothing.
So stream mux waits until input blocks pass a given number of samples and it
takes forever
Regards
Jeon
2015. 7. 9. 오전 11:27에 "Nowlan, Sean"
<sean.now...@gtri.gatech.edu<mailto:sean.now...@gtri.gatech.edu>>님이 작성:
I’m somehow getting a simple flowgraph to lock up GNU Radio. It locks up every
time I run it, after roughly the same amount of time. As you can see in the
attached image and GRC file, I’m feeding two inputs of a Stream Mux block from
the same upstream block. Do you imagine why that might cause problems?
I know there are other ways to do what I’ve shown here, but locking up seems
like a bug.
Thanks,
Sean
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