Specify noutput_items for each output in work function

Question

I want to modify a OOT block to have two outputs, as follow :

Current state :

    int
    block_impl::general_work (int noutput_items,
                       gr_vector_int &ninput_items,
                       gr_vector_const_void_star &input_items,
                       gr_vector_void_star &output_items)
    {
        const gr_complex *in = (const gr_complex *) input_items[0];
        gr_complex *out = (gr_complex *) output_items[0];        
        
        // signal processing part 

        switch (state) {
          case SEND: {
            // Send one complex vector to "out"
            noutput_items = 1;
          }
          case NOK:  {
            // Do nothing
            noutput_items = 0;
          }
        }
        return noutput_items;
     }

And I tried :

    int
    block_impl::general_work (int noutput_items,
                       gr_vector_int &ninput_items,
                       gr_vector_const_void_star &input_items,
                       gr_vector_void_star &output_items)
    {
        const gr_complex *in = (const gr_complex *) input_items[0];
        gr_complex *out = (gr_complex *) output_items[0];
        gr_complex *out_all = (gr_complex *) output_items[1];
        
        // signal processing part 

        switch (state) {
          case SEND: {
            // Send one complex vector to "out" and "out_all"
            noutput_items = 2;
          }
          case NOK:  {
            // Send complex vector to "out_all"
            noutput_items = 1;
          }
        }
        return noutput_items;
     }

However, this solution is not working as the block connected to "out_all" is not receiving anything and the block connected to "out" is not working properly anymore.

I guess my understanding of the "noutput_items" value to return at the end of the work function is not total, can someone explain to me what I'm missing ?

Answer 1

You can use the produce function as follow :

    int
    block_impl::general_work (int noutput_items,
                       gr_vector_int &ninput_items,
                       gr_vector_const_void_star &input_items,
                       gr_vector_void_star &output_items)
    {
        const int OUT = 0;
        const int OUT_ALL = 1;

        const gr_complex *in = (const gr_complex *) input_items[0];
        gr_complex *out = (gr_complex *) output_items[OUT];
        gr_complex *out_all = (gr_complex *) output_items[OUT_ALL];
        
        // signal processing part 

        switch (state) {
          case SEND: {
            // Send one complex vector to "out" and "out_all"
            produce(OUT,1);
            produce(OUT_ALL,1);
          }
          case NOK:  {
            // Send complex vector to "out_all"
            produce(OUT,0);
            produce(OUT_ALL,1);
          }
        }
        return WORK_CALLED_PRODUCE;
     }