On Wed, Jun 4, 2014 at 2:22 PM, xianda <[email protected]> wrote:
> Hi all:
> I want to know something about the forecast().
> I have already known that forcast() can tell scheduler how many
> input items are required for each output item.
> 1.But now i have read two example:
> The first one:
> void your_block::forecast(int
> noutput_items,gr_vector_int &ninput_items_required){
>
> ninput_items_required[0]=100 *
> noutput_items;
> ninput_items_required[1]=100 *
> noutput_items; }
>
>
In your first example above, you have exactly two input ports.
That's why you need to specify "ninput_items_required[0]" and
"ninput_items_required[1]", there are in total 2 ports.
In fact in this example the value of "ninput_items_required.size()" is 2.
In alternative, you could also replace above two lines with:
for (unsigned i=0; i < 2; i++)
ninput_items_required[i] = 100 * noutput_items;
Or, to be more generic, you could also use this:
for (unsigned i=0; i < ninput_items_required.size(); i++)
ninput_items_required[i] = 100 * noutput_items;
>
> 2.I want to know if we use the general_work().Is it means that
> we must use the forcast()?Thanks.
> Best regards
>
>
If you use "general" block, you need to specify "forecast()".
"General" block has "general_work()" function but not "general()" function.
If you use sync block, decim, interpolation block etc, you have "work()"
but not "general_work()", and you don't need to write "forecast()".
This is very straight-forward.
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