Re: [Discuss-gnuradio] Details on USB buffer

[Stefan Bruens]

On Friday 27 February 2009 01:05:52 Tony wrote:
> The USRP C++ example program uses this code to move USRP USB data into a
> buffer:
>
>       urx->read(&buf, bufsize, &overrun);
>
> If this line is called many times in a short period of time will the buffer
> have some of the data leftover from previous read(s)?  Can I assume that
> the OS will not return the buffer until the next n bytes have been
> received?
>
> Tony 

The read is a blocking read. The return value is the number of bytes actually 
read, which will always be the same as bufsize or an error value (<0). Samples 
may be thrown away in the USRP itself this is called an overrun, in this case 
the corresponding variable will be set to true.

Stefan

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