Query regarding the print method that is used by the ovm_printer

OVM
1

Hi All,

I have a query related to print method in the OVM, i would explain it with the below mentioned source code:

import ovm_pkg::*;
class a_check extends ovm_transaction;
  
   int a_inst;
  `ovm_object_utils_begin(a_check)
  `ovm_field_int(a_inst,OVM_ALL_ON);
  `ovm_object_utils_end
  
  function new(string name = "a_check");
   super.new(name);
  endfunction 
  
  function void print_fields();
    this.print();
  endfunction
  
endclass

class b_check extends a_check;
  
  int b_inst;
  
  `ovm_object_utils_begin(b_check)
  `ovm_field_int(b_inst,OVM_ALL_ON);
  `ovm_object_utils_end
  
  
  function new(string name = "b_check");
    super.new(name);
  endfunction 
  
  function void print_fields_b();
   this.print();
  endfunction
endclass

module tb_top;
  
  import ovm_pkg::*;
  
  initial begin
    b_check b_inst;
    b_inst = b_check::type_id::create("b_inst");
    b_inst.print_fields_b();
  end
  
endmodule

Here i have two print methods, one in the parent class a_check(print_fields() method) and one in the child class b_check (print_fields_b() method).
I have called the print method of the child class b_check in the module, i observe that the properties of the parent class a_check are also getting printed.
It is obvious that because of inheritance the parent class properties are getting printed, from the print method of the child class b_check.
The OVM print statement is as below :

Name Type Size Value

b_check b_check - b_check@6
a_inst integral 32 'h0
b_inst integral 32 'h0

My query is that is there any switch in the print method of the OVM so that i get the only print of the properties of child class properties.

2

In reply to nchakravarthy:

No, and you can’t override the `ovm_field_* macros either.

We strongly recommend against using any of the the `ovm_field macros for their extremely poor performance, as well as many other issues. See OVM/Transaction/Methods | Verification Academy for a better approach.

3

In reply to dave_59:

Thanks dave for your inputs

I have tried overriding the do_print() method and print the user defined messages, this is the source code:

import ovm_pkg::*;
class a_check extends ovm_transaction;
 
   int a_inst;
  `ovm_object_utils_begin(a_check)
  `ovm_field_int(a_inst,OVM_ALL_ON);
  `ovm_object_utils_end
 
  function new(string name = "a_check");
   super.new(name);
  endfunction 
 
  function void print_fields();
    this.print();
  endfunction
  
  virtual function void do_print(ovm_printer printer);
    printer.print_field("a_inst",0,32);
   endfunction
 
endclass
 
class b_check extends a_check;
 
  int b_inst;
 
  `ovm_object_utils_begin(b_check)
  `ovm_field_int(b_inst,OVM_ALL_ON);
  `ovm_object_utils_end
 
 
  function new(string name = "b_check");
    super.new(name);
  endfunction 
 
  function void print_fields_b();
   this.print();
  endfunction
  
  virtual function void do_print(ovm_printer printer);
    printer.print_field("b_inst",0,32);
  endfunction
endclass
 
module tb_top;
 
  import ovm_pkg::*;
 
  initial begin
    b_check b_inst;
    b_inst = b_check::type_id::create("b_inst");
    b_inst.print_fields_b();
  end
 
endmodule

I have declared do_print() methods both in the parent class a_check and child class b_check

Assumption is if the do_print() method is overridden in the class scope and if we call print() method of that particular class then the do_print method should be executed.

But am observing different behavior as i have called the method(print_fields_b()) of the child class b_check, expecting that only the do_print() method of the child class b_check must be executed.

Observing that it is printing the all the properties and then it is printing the user defined print statements presnt in the do_print() method of the child class b_check

The transcript is :

Name Type Size Value

b_inst b_check - b_inst@4
a_inst integral 32 'h0
b_inst integral 32 'h0
b_inst integral 32 'h0

so here b_inst is printed twice, Pleasecorrect me if am wrong in understanding the do_print() method of the OVM

4

In reply to nchakravarthy:

do_print() is a hook that appends to what the field macros have already set up.

Change

 `ovm_object_utils_begin(b_check)
 `ovm_field_int(b_inst,OVM_ALL_ON);
 `ovm_object_utils_end

to

 `ovm_object_utils(b_check)