Local variables in CoverGroup

SystemVerilog
1

Hi There,

Can I have a local variable in a covergroup?

Can I have a user defined new function for a covergroup?

Thanks,
Sunil.

2

In reply to KumarSunilB:

No and No. What are you looking to accomplish?

3

In reply to dave_59:

I am trying to do something like below (not exactly same but similar).



covergroup TYPE_t2_cg with function sample(TYPE_t2 item);
   
      option.per_instance = 1;
   
      bit signed [`NUM:0] min;
      bit signed [`NUM:0] max;

      byte data_type;
      byte data_size;

      function new(byte d_type, byte d_size);
         data_type = d_type;
         data_size = d_size;

         if(data_type == 1) begin
            min = 0;
            max = (2**data_size);
         end
         else if(data_type == 2) begin
            min = (2**data_size+1);
            max = (3**data_size);
         end
      endfunction

      cp_opA : coverpoint item.opA
         {
            bins b_min          = {  min              };
            bins b_lower        = {[(min+ 1):(min+10)]};
            bins b_intermediate = {[(min+11):(max-11)]};
            bins b_higher       = {[(max-10):(max- 1)]};
            bins b_max          = {  max              };
         }

   endgroup

   function void some_function(TYPE_t1 s);

      TYPE_t2_cg i_cg[byte][byte];

      TYPE_t2 item;

      item.map(s);

      if(NULL == i_cg[s.data_type][s.data_size]) begin
         i_cg[s.data_type][s.data_size] = new(s.data_type, s.data_size);
      end

      i_cg[s.data_type][s.data_size].sample(item);

   endfunction
4

In reply to KumarSunilB:
You could do this as a function before constructing the covergroup

 typedef bit signed [`N:0] intN;
 function void TYPE_t2_new(input byte data_type, data_size, output intN min, max);
         if(data_type == 1) begin
            min = 0;
            max = (2**data_size);
         end
         else if(data_type == 2) begin
            min = (2**data_size+1);
            max = (3**data_size);
         end
endfunction
covergroup TYPE_t2_cg(intN min, max)  with function sample(TYPE_t2 item);
      option.per_instance = 1;
      cp_opA : coverpoint item.opA
         {
            bins b_min          = {  min              };
            bins b_lower        = {[(min+ 1):(min+10)]};
            bins b_intermediate = {[(min+11):(max-11)]};
            bins b_higher       = {[(max-10):(max- 1)]};
            bins b_max          = {  max              };
         }
 
   endgroup
 
   function void some_function(TYPE_t1 s);
      intN min, max;
      TYPE_t2_cg i_cg[byte][byte];
 
      TYPE_t2 item;
 
      item.map(s);

      if(NULL == i_cg[s.data_type][s.data_size]) begin
         TYPE_t2_new(s.data_type, s.data_size, min, max)
         i_cg[s.data_type][s.data_size] = new(min, max);
      end
 
      i_cg[s.data_type][s.data_size].sample(item);
 
   endfunction
5

In reply to dave_59:

Thanks Dave.

However I see issue in the following line

→ if(0 == i_cg[s.data_type][s.data_size])

Is it legal to check if the covergroup is initialized or not by comparing it to 0?

Sunil.

6

In reply to KumarSunilB:

handles can only be compared to other handles or NULL. so 0 is not allowed.

7

In reply to dave_59:

Thanks Dave.