There is a performance issue with this.  If your program needs to manipulate 
the raw data, but at the same time provide that raw data to another branch(es), 
a copy much be made.  If this is the case, then it would make more sense to 
duplicate the data in parallel as it enters the system.  This should be more 
efficient than memcopy.

I am looking into DMA to see if this is possible.

Regards,

Mark McCarron

From: m...@ettus.com
Date: Thu, 16 May 2013 20:51:32 -0700
Subject: Re: [Discuss-gnuradio] Question about UHD driver
To: mark.mccar...@live.co.uk
CC: discuss-gnuradio@gnu.org


There is no need to create multiple copies.  The consuming blocks are each 
given a pointer to the same data, and the memory is not freed until all the 
consuming blocks indicate they are done with it.


Matt

On Thu, May 16, 2013 at 11:00 AM, Mark McCarron <mark.mccar...@live.co.uk> 
wrote:





I am wondering if the UHD driver has the ability to create multiple copies of 
the stream in memory???

Let's say I have a flow-graph that has two branches, the first pushes complex 
data to an FFT, whereas the second demodulates a portion of that data into AM.



Does the driver supply a single stream, which is then copied by the 
application?  Or does it create two copies of the stream and allow each branch 
of the flow-graph to manipulate the data via pointers?

I'm digging into DMA to see if this is possible, I would be surprised if there 
was a limitation here.



Regards,

Mark McCarron                                     

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