Nathan, thanks for the reply. This can actually explain a discrepency I see in another custom quad demod block I have.
So what does that mean in terms of the value when I access in[noutput_items]? If I get noutput_items=8192, does it align like this? in[0] = history1 in[1] = history2 in[2..8191]=data? in[8192]=??? or is it more like: in[0] = history1 in[1] = history2 in[2..8193]=data [8192 bytes following 2 history] ---------- Forwarded message ---------- From: West, Nathan <[email protected]> Date: Mon, May 1, 2017 at 2:48 PM Subject: Re: [Discuss-gnuradio] What value is in in[noutput_items+1]? To: Ghost Op <[email protected]> Cc: "[email protected]" <[email protected]> That block calls set_history(2), so in[0] is actually the last sample in 'in' from the previous call to work. On Mon, May 1, 2017 at 2:09 PM, Ghost Op <[email protected]> wrote: > I was looking back over the Quadrature Demod code and I happened to > notice something unusual. The call to the Volk multiply conjugate > routine appears to use in[noutput_items+1] on the last calculation. > > Here's the call: > volk_32fc_x2_multiply_conjugate_32fc(&tmp[0], &in[1], &in[0], > noutput_items); > > It obviously works correctly, and the buffer's bigger than > noutput_items so it doesn't seem to cause a memory access issue. > > So my question is: when volk uses the memory at in[noutput_items+1] > what value is it using? Is it using a zeroed byte, something from a > history buffer, or whatever happened to be there? > > Would anyone have any insight? > > Thanks! > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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