Re: [Discuss-gnuradio] Custom Blocks and Number of Items Per Port

[Martin Braun (CEL)]

On Fri, Aug 03, 2012 at 02:23:39PM -0400, Alexander Olihovik wrote:
> It seems as if the gr_sync_block is close to what Josh Blum refers to as an
> Arbitrary Ratio Block in his Blocks Coding Guide.

Read the guide again :)
that's not at all what it is.

This might also help:
http://gnuradio.org/redmine/projects/gnuradio/wiki/TutorialsCoreConcepts

...not quite finished, though.

> Do you think if I were to use the forecast() function and make all
> ninput_items_required[i] to be the same set amount, I would always have the
> same number of input_items[i] on each port every time the work() function is
> called? Is it this simple?

There should be no reason at all for wanting to have the same number of
input_items at every port. Leave that to the scheduler. Just consume
whatever items you need every time work() is called.

MB


> 
> 
> On Fri, Aug 3, 2012 at 1:56 PM, Martin Braun (CEL) <address@hidden>
> wrote:
> 
> 
>     On Fri, Aug 03, 2012 at 01:38:38PM -0400, Alexander Olihovik wrote:
>     > There are a few cases when input_items[0] doesn't equal input_items[1].
>     If say,
>     > len(input_items[0]) = 1000 and len(input_items[1]) = 1500, and I 
> returned
>     the
>     > smaller of the two values, 1000, what would happen to the other 500
>     samples on
>     > port 1? Would they be buffered somewhere and then used the next time the
>     work
>     > function is called?
> 
> 
>     Yep. The case where the len(input_items) are different is what you
>     should normally prepare for.
> 
>     Are you *certain* you can't use a gr_sync_{block,decimator,interpolator}?
>     That would make stuff much easier for you, I guess. For a start, you
>     wouldn't even need to check input_items.
> 
>     MB
> 
> 
>     >
>     >
>     > On Wed, Aug 1, 2012 at 8:40 PM, Tom Rondeau <address@hidden> wrote:
>     >
>     >
>     >     On Wed, Aug 1, 2012 at 3:46 PM, Alexander Olihovik <
>     address@hidden>
>     >     wrote:
>     >     > Hi all!
>     >     > I'm writing a custom sink block in Python with multiple input 
> ports
>     of
>     >     all
>     >     > the same data type.
>     >     > I've been reading Josh's block coding guide, but I'm confused at
>     one
>     >     point:
>     >     > The value returned by a block should be the number of items
>     produced by
>     >     that
>     >     > block.
>     >     > Is this to say that if I have multiple ports, I may return the
>     value of
>     >     > input_items[0]?
>     >     > Or is it correct to say that I must return the sum of all
>     input_items[i],
>     >     i
>     >     > = range(number of input ports)?
>     >     >
>     >     >
>     >     > I would like to create a synchronous block where all ports consume
>     and
>     >     > produce an equal number of items every time the work function is
>     called.
>     >     > However, it appears that there are times when input_items[0] !=
>     >     > input_items[1] != ... != input_items[numPorts-1]
>     >     > If I were to return input_items[0], I would assume that this would
>     not
>     >     yield
>     >     > the results I expect!
>     >     >
>     >     > Any help is greatly appreciated!
>     >     >
>     >     > From,
>     >     > Alex
>     >
>     >
>     >     If you have a block with multiple input items and you want to 
> produce
>     >     the same number every time, noutput_items will tell you how much you
>     >     are capable of producing on every output stream. When you 'return
>     >     noutput_items', you are saying that you have produced that many 
> items
>     >     on EVERY stream.
>     >
>     >     There is another way that specifies the same thing. Each block
>     >     consumes some number of samples on every input stream and produces
>     >     some number of samples on every output stream. You can individually
>     >     specify "produce(i, N_i)" and "consume(o, N_o)" on each input and
>     >     output stream, respectively. In this case i is the input stream and
>     >     N_i is the number of items consumed on that input stream and o is 
> the
>     >     output stream and N_o is the number of items consumed on that output
>     >     stream. When specifying your own 'produce' values, though, make sure
>     >     to return WORKED_CALLED_PRODUCE, to tell the scheduler that you have
>     >     done this yourself. But it sounds like you want to produce the same
>     >     amount on every stream, so you should be fine just using 'return
>     >     nouput_items'.
>     >
>     >     Tom
>     >
>     >
>     >
>     >
>     > --
>     > Alex Olihovik
>     > University of Virginia 2013
>     > BS Electrical Engineering
>     > BS Computer Engineering
>     > address@hidden
> 
> 
>     > _______________________________________________
>     > Discuss-gnuradio mailing list
>     > address@hidden
>     > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
> 
>     --
>     Karlsruhe Institute of Technology (KIT)
>     Communications Engineering Lab (CEL)
> 
>     Dipl.-Ing. Martin Braun
>     Research Associate
> 
>     Kaiserstraße 12
>     Building 05.01
>     76131 Karlsruhe
> 
>     Phone: +49 721 608-43790
>     Fax: +49 721 608-46071
>     www.cel.kit.edu
> 
>     KIT -- University of the State of Baden-Württemberg and
>     National Laboratory of the Helmholtz Association
> 
>     _______________________________________________
>     Discuss-gnuradio mailing list
>     address@hidden
>     https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
> 
> 
> 
> 
> --
> Alex Olihovik
> University of Virginia 2013
> BS Electrical Engineering
> BS Computer Engineering
> address@hidden

> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio


-- 
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin Braun
Research Associate

Kaiserstraße 12
Building 05.01
76131 Karlsruhe

Phone: +49 721 608-43790
Fax: +49 721 608-46071
www.cel.kit.edu

KIT -- University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association

pgp741n61sFOb.pgp
Description: PGP signature