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 <t...@trondeau.com> wrote:
>
>
> On Wed, Aug 1, 2012 at 3:46 PM, Alexander Olihovik <ano...@virginia.edu>
> 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
> ano...@virginia.edu
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