Re: [Discuss-gnuradio] Writing own gnuradio Block, optional output port

[Chris Kuethe]

If the delayed signal is optional, why not just use a delay block when you need a delayed signal?

[your_source]--+-->[do_stuff]-------------------+

               |                                |    ____________

               |                                +-->[ something  ]

               |                                    | that uses  |-->[output]

               |                                +-->[_both_paths_]

               |                                |

               +-->[delay]--->[do_other_stuff]--+

On Wed, Dec 16, 2015 at 2:40 PM, Charles Bridger <address@hidden> wrote:

I've created a signal source and want to create a second port which outputs the same signal, except one sample behind. The problem I'm having is that I don't know how to make it "optional". If I change the code in the private constructor from:

[Constructor Code}

...

gr::io_signature::make(1,1,sizeof(float)),

....

 to 

gr::io_signature::make(1,2,sizeof(float)),

It still makes me  plug something into the port when I use the block in GRC, even when I don't want to use the second output port.

I don't know if my code in the work method is relevant but I address the tw output ports like this:

float *out0 = (float *) output_items[0];

float *out1 = (float *) output_items[1];

for(int i = 0; i < noutput_items; i++)

{

    out0[i] = stuff;

    out1[i] = stuff - 1; // <- I want that to be optional when I put the block in GRC.

}

I've also tried setting the io_signature::make to 1,-1,sizeof(float) but that's less than ideal and doesn't work if in GRC i set number of outputs to 1.

Again thank you all for your time.

Cheers,

Charles 

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