Modport

SV Verification Directory

Modport

The modport construct within an interface module is used to group signals and specify their directionality. By assigning port directions, modport enforces access control, restricting signals to specific roles and clearly defining their intended function within the interface.

The modport keyword is employed to establish these signal definitions within an interface.

• Modport provides input, output, inout and ref as port declarations.
• Signals that are driven should be declared as outputs in the modport module.

Example Code

• Design

  module add (intf m_intf);
  
    assign m_intf.s = m_intf.a + m_intf.b;
  
  endmodule
  

• Testbench

  interface intf();
    logic [3:0] a;
    logic [3:0] b;
    logic [4:0] s;
  
          modport driver (output a, b, input s);
  
  endinterface
  
  module test;
  
    intf i_intf();      //interface handle declaration
  
    add DUT (i_intf);   // using interface handle name instead of post declaration
  
    initial begin
      $display("---------- ADDER ----------");
      repeat(10) begin
        i_intf.a = $random();
        i_intf.b = $random();
        #1;
        $display("a = %d, b = %d => s = %d", i_intf.a, i_intf.b, i_intf.s);
      end
    end
  endmodule
  

  Execute the design in EDA Playground