SV: [Discuss-gnuradio] fundamentals of block-connections, message queue etc.

[Ulrika Uppman]

Hi Milo,
As I understand (if we're still are talking about the 802.11b code), the tx 
side uses multiple message queues "in between" the processing blocks to handle 
the different data rates. I'm not sure I understand your question, but yes the 
detete_head() function is used to extract messages from the queue. Take a look 
in the bbn_80211b_pkt.py and I think you will see how the message queues are 
used there.

/Ulrika
________________________________

Från: Milo Wong [mailto:address@hidden 
Skickat: den 26 augusti 2009 06:47
Till: Colby Boyer
Kopia: Ulrika Uppman; GNU Radio Discussion
Ämne: Re: [Discuss-gnuradio] fundamentals of block-connections, message queue 
etc.


Hi Colby,

Based on what you said, is that means, at Tx side, the encoded data stream from 
encoder should also be loaded into gr.msg_queue() and applies delete_head() 
funtion?

Thank you,

Milo


On Tue, Aug 25, 2009 at 8:08 PM, Colby Boyer <address@hidden> wrote:


        Within the BBN RX side, all the processing blocks are stuck together so 
that data "streams" from each block to the next. In the final block, when a 
packet is successfully decoded it is loaded in a message queue.  The loading 
into the message queue is done within the C++ code, not the python.
        
        There is another thread running that will sleep on an empty queue and 
will not wake up until something is inserted into the queue. When a message 
enters the queue, the thread wakes up, takes out the message and then prints it 
out via a call back function.
        
        Check the source code for the message queue to see if there is another 
function to add a message.
        
        Thanks,
        Colby 


        On Tue, Aug 25, 2009 at 8:08 AM, Ulrika Uppman <address@hidden> wrote:
        

                Hi everyone,
                I'm trying to get a grip of how the software code works in 
gnuradio. At the moment I'm looking at the bbn 802.11b rx implementation.
                
                I would like to understand how the data stream is transported 
from the usrp source block and further to the rest of the processing blocks 
that are connected together. There is a message queue involved, but how and 
where is the data added to the queue? Is there another way of putting data in 
the message queue than using the inset_tail function?
                
                I have read the general documentation on how the gnuradio code 
is built by David Shen, and I have also been reading the gr code, but I still 
can't seem to figure it all out. Can someone please point me in the right 
direction on where to look for this kind of documentation?
                
                Thanks!
                /Ulrika
                
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