verilator/test_regress/t/t_force_mid.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain, for
// any use, without warranty, 2021 by Wilson Snyder.
// SPDX-License-Identifier: CC0-1.0

`define stop $stop
`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got='h%x exp='h%x\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0)

module t(/*AUTOARG*/
   // Outputs
   topout,
   // Inputs
   clk, topin
   );

   input clk;
   input [3:0] topin;
   output [3:0] topout;

   integer cyc = 0;

   assign topout = 4'b0101;

   always @ (posedge clk) begin
      cyc <= cyc + 1;
      if (cyc == 0) begin
         if (topout != 4'b0101) $stop;
         if (topin != 4'b1001) $stop;
      end
      else if (cyc == 1) begin
         force topout = 4'b1010;
      end
      else if (cyc == 2) begin
         if (topout != 4'b1010) $stop;
         release topout;
      end
      else if (cyc == 3) begin
         if (topout != 4'b0101) $stop;
      end
      else if (cyc == 4) begin
         force topin = 4'b1100;
      end
      else if (cyc == 5) begin
         if (topin != 4'b1100) $stop;
         release topin;
      end
      else if (cyc == 6) begin
         if (topin != 4'b1001) $stop;
      end


      //
      else if (cyc == 99) begin
         $write("*-* All Finished *-*\n");
         $finish;
      end
   end

endmodule