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[Discuss-gnuradio] Re: Help with Verilog: write_count

From: seph 004
Subject: [Discuss-gnuradio] Re: Help with Verilog: write_count
Date: Tue, 21 Nov 2006 06:08:26 -0800 (PST)

Message: 4
Date: Mon, 20 Nov 2006 08:15:50 -0800
From: Eric Blossom <address@hidden>
Subject: Re: [Discuss-gnuradio] Re: Help with Verilog: write_count
To: seph 004 <address@hidden>
Cc: address@hidden
Message-ID: <address@hidden>
Content-Type: text/plain; charset=us-ascii

>I'm not sure of which max_bytes variable you are referring to.

It's declared like this in main()

int   max_bytes = 128 * (1L << 20);

and it's used here:

test_output (usrp_standard_tx *utx, int max_bytes, double ampl,
         bool dc_p, bool counting_p)
seemingly to determine how many times to run the loop that puts samples into the write buffer.

>Nope.  It knows how to deal with _only_ 512 byte packets.  
>Remember those questions about WR & ~count[8]?

I see. So 512 byte packets represent 256 I and Q 16 bit samples? And if the FIFO is 4096 bits in capacity, it can only fit 8 packets worth of samples. So if I told the host to send 128 16-bit samples exactly, that would come to 2 packets, and  my FIFO should only be half full? Sorry for the silly questions, I just want to make sure I haven't missed something. If sending 128 samples exactly is possible, from where could you achieve this if not via the max_bytes variable?

>If you're patient, the in-band signaling plus mblocks that we're
>talked about on the list will get you closer.  All of this is unlikely
>to come together until sometime in Q1.   Good progress is being made
>on the mblocks, but we have yet to actually start refactoring all the
>USRP host and verilog code.

The m-block stuff does sound exciting, and may solve some issues I'm having. I've lost a lot of time already though, so I have to press on with this.

>Good luck!




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