verilator/test_regress/t/t_interface1.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2013 Wilson Snyder
// SPDX-License-Identifier: CC0-1.0

// Very simple test for interface pathclearing

interface ifc;
  logic [3:0] value;
endinterface

module t (
    input clk
);

  integer cyc = 1;

  ifc itop ();

  sub c1 (
      .isub(itop),
      .i_value(4'h4)
  );

  always @(posedge clk) begin
    cyc <= cyc + 1;
    if (cyc == 20) begin
      if (c1.i_value != 4) $stop;  // 'Normal' crossref just for comparison
      if (itop.value != 4) $stop;
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end
endmodule

module sub (
    ifc isub,
    input logic [3:0] i_value
);

  always @* begin
    isub.value = i_value;
  end
endmodule : sub