Randomizing a dynamic array size

SystemVerilog
, , ,
3

You have a number of problems with your code, the biggest one is you forgot to declare size as rand.


class Object;
   rand int id;
endclass

class Objects;
   rand Object lst[];
   rand int size; // you forgot to declare rand
   
   constraint default_size {
      size > 0 && size < 6;
   }
   
   constraint default_lst {
      lst.size() == size;
   }
   // A better way to write these constraints without size
    constraint size_c { lst.size() inside {[1:5]};}
   
   function void post_randomize();
      lst 	 = new[size];
      foreach (lst[i]) begin
	 lst[i]     = new; // need to construct each element
	 lst[i].id  = i;
      end
   endfunction
   
endclass

module test1; // don't use program blocks
   Objects objs; // declare static variables outside of initial blocks
   
   initial begin
      objs  = new;
      void'(objs.randomize()); // normally should check the result 
      $display("Allocated an array of size=%0d", objs.lst.size());
   end
endmodule : test1