On Thu, Jan 08, 2009 at 12:44:18PM -0800, Earle Frank wrote: > > Eric Blossom wrote: > > > > Let's say that block D never produces an output, but is consuming all > > of it's input. Can you see how this leads to a hang? > > > > I can see that will cause the flow graph to hang. And I followed your > explanation. > I have added a "timeout" feature to block D, so that after a maximum of M > samples, block D will output the appropriate enable signal. > So now it is impossible for block D to consume all inputs and never produce > an output. > > Let me further describe my test: > Let N=100, M=40. > The expected enable signal out of block D is: > 0 for n=0 to 49 > 1 for n=50 to 79 > 0 for n=80 to 89 > 1 for n=90 to 109 > 0 for n=110 to 199 > > Block A produce 100 samples to it's output buffer. > Block B consumed all 100 samples of it's input and produced 100 samples to > it's output buffer. > Block C consumed all 100 samples of it's input and produced 100 samples to > it's output buffer. > > Block D consumed all 100 samples of it's input and produced the correct > enable signal for n=0 to 89. > The state inside block D is now 10, because it saw the beginning of an event > from n=90 to 99. It is waiting for the event to end or for the state to > reach M=40. > > Block E consumed 90 input samples from the input buffer from B and from the > input buffer from D to produce 30 outputs. These outputs are simply the > values from block B at n=50 to 79. > > > Eric Blossom wrote: > > > > It goes like this. E ends up BLKD_IN on it's second input, but > > meanwhile the buffer on it's first input is full. It's full because B > > has been writing it as quickly as it can. Once E's first input buffer > > (== B's output buffer) is full. B becomes output blocked. It will > > never run again because it's got nowhere to put it's output. > > > > Shouldn't the output buffer be nearly empty for block B now? Block E has > consumed 90 of the 100 samples from block B. > Shouldn't block B be able to process another 90 samples or even 100 samples > (assuming the output buffer is big enough)? > > Why doesn't block A produce the next 100 samples to it's output buffer? And > if it does, why doesn't block C consumed those 100 samples? And also, why > doesn't block B consume at least 90 of those 100 samples?? > > > Thanks again for all the insight > EF
Doesn't C do a set_output_multiple(N(==100))? If so, and there's only 90 samples available it won't run. You're on your own from here. This is K7GNU, clear. Eric _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
