[Discuss OpenCPI] Limit on buffer size due to ocpi_buffer_size_* property

From: <dwp_at_md1tech.co.uk>
Date: Fri, 16 Jun 23 09:00:56 +0000

Hello,

Is there a particular reason why the `ocpi_buffer_size_*` properties are restricted to 16 bit?\
This results in quite a small limit on the amount of data that can be sent over a single buffer.

I am trying to send the output of an FFT (as floats) and this is limiting the size of the FFT I can do to 4096. (When sticking to powers of 2)

I would have expected that even with the limit in place I would be able to send 8192 floats in a single buffer but when I set the `sequenceLength` property in the protocol to 8192 I get this error:

`Exiting for exception: Value for property "ocpi_buffer_size_out" of instance "fft" of component "local.uhd.uhd.fft" is invalid for its type: for property ocpi_buffer_size_out: Expression value (6.5536e4) is out of range for UShort type properties (0 to 6.5535e4)`

I know that I could serialise the data and send it over multiple buffers however this would introduce additional time and space complexity copying memory in and out of extra buffers.

Thanks in advance,\
Dan






Received on Fri Jun 16 2023 - 09:00:56 CDT