How to ignore specific covergroup instances of a multi dimensional dynamic array covergroup instantiation

Question

I have a covergroup something like this

  covergroup cover_routers with function sample(bit inj_val,eje_val);
   option.per_instance = 1; 

    inj_val_cp : coverpoint inj_val
                  {
                   bins inject_valid[] = {[0:1]};
                  } 
    eje_val_cp : coverpoint eje_val
                  {
                    bins eject_valid[] = {[0:1]};
                  }   
   endgroup

Below I have multi dimentional dynamic array instance of the covergroup. Since it is a 8x4 array, so there will be 32 instances of the covergroup cov_routers but I want to exclude certain instances based on values of i and j, where i and j are two dimensions of the array, If I don't do so, it shows holes in covergroup instances in verdi

For some values of i and j, I dont want coverage i.e just for example for the following instances of covergroups I don't want coverage,

cov_routers[2][0]; cov_routers[2][1], cov_routers[2][2], cov_routers[7][3] and cov_routers[7][2]

I don't want to sample them so I tried doing something like following:

   class my_cov extends ovm_component;
    `ovm_component_utils_begin(my_cov)
    `ovm_component_utils_end
    cover_routers cov_routers[][];// ixj= 8x4 array
     function new(input string name = "my_cov", ovm_component parent = null);
     super.new(name,parent);
     endfunction
     
     function void build();
     super.build();
      cov_routers  = new[8]; 
          foreach(cov_routers[i])
          begin
             if (i==2)
             cov_routers[i] = new[1]; // since i want coverage only for 1 instance cov_routers[2][3] 
             else if (i==7)
             cov_routers[i] = new[2];// since i want cov only for cov_routers[7][0] & cov_routers[7][1]
              else 
              cov_routers[i] = new[4];
              end

              for (int i=0; i<8; i++) 
              begin
                 for (int j=0; j<4; j++)
                 begin
                   if (((i==2) && (j ==0))||((i==2) && (j ==1))||((i==2) && (j ==2))||((i==7)&&(j==3))||((i==7)&&(j==2))
                   begin
                 //do nothing
                   end
                   else
                   begin
                    cov_routers[i][j] =new;
                   end
                  end
                 end

          task run();
            super.run();
              fork
              router_coverage();
              join
           endtask

           task automatic router_coverage();
           for (int p=0; p<8; p++) 
              begin
              automatic int i=p;
                 for (int q=0; q<4; q++)
                 begin
                 automatic int j=q;
                  if (((i==2) && (j ==0))||((i==2) && (j ==1))||((i==2) && (j ==2))||((i==7)&&(j==3))||((i==7)&&(j==2))
                  begin
                  // do nothing
                  end
                  else
                  begin
                   fork
                   begin
                   router_c(i,j)
                   end
                   join_none
                  end
               endtask

            task automatic router_c(int i, int j);
            forever
            begin
            .....waiting for clock
            .....sampling coverpoints inj_val  and eje_val through proprietary fns
            cov_routers[i][j].sample(inj_val, eje_val)
            end
            endtask

but when I do sampling of following instance in run task, it gives the error below

                     cov_routers[2][3].sample(....)

Error-[NOA] Null object access The object is being used before it was constructed/allocated. Please make sure that the object is allocated before using it.

Please help me with what I am doing wrong here or is there any other easier way of ignoring coverage for certain instances of covergroups, I will be very grateful

How to ignore specific covergroup instances of a multi dimensional dynamic array covergroup instantiation

Answers (1)

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