verilator/test_regress/t/t_EXAMPLE.v

// DESCRIPTION: Verilator: Verilog Test module
//
// Use this file as a template for submitting bugs, etc.
// This module takes a single clock input, and should either
//      $write("*-* All Finished *-*\n");
//      $finish;
// on success, or $stop.
//
// The code as shown applies a random vector to the Test
// module, then calculates a CRC on the Test module's outputs.
//
// **If you do not wish for your code to be released to the public
// please note it here, otherwise:**
//
// This file ONLY is placed under the Creative Commons Public Domain, for
// any use, without warranty, 2025 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=%0x exp=%0x (%s !== %s)\n", `__FILE__,`__LINE__, (gotv), (expv), `"gotv`", `"expv`"); `stop; end while(0);
`define checks(gotv,expv) do if ((gotv) != (expv)) begin $write("%%Error: %s:%0d:  got='%s' exp='%s'\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);

module t(/*AUTOARG*/
   // Inputs
   clk
   );
   input clk;

   int cyc;
   reg [63:0] crc;
   reg [63:0] sum;

   // Take CRC data and apply to testblock inputs
   wire [31:0] in = crc[31:0];

   /*AUTOWIRE*/
   // Beginning of automatic wires (for undeclared instantiated-module outputs)
   wire [31:0]          out;                    // From test of Test.v
   // End of automatics

   Test test(/*AUTOINST*/
             // Outputs
             .out                       (out[31:0]),
             // Inputs
             .clk                       (clk),
             .in                        (in[31:0]));

   // Aggregate outputs into a single result vector
   wire [63:0] result = {32'h0, out};

   // Test loop
   always @(posedge clk) begin
`ifdef TEST_VERBOSE
      $write("[%0t] cyc==%0d crc=%x result=%x\n", $time, cyc, crc, result);
`endif
      cyc <= cyc + 1;
      crc <= {crc[62:0], crc[63] ^ crc[2] ^ crc[0]};
      sum <= result ^ {sum[62:0], sum[63] ^ sum[2] ^ sum[0]};
      if (cyc == 0) begin
         // Setup
         crc <= 64'h5aef0c8d_d70a4497;
         sum <= '0;
      end
      else if (cyc < 10) begin
         sum <= '0;
      end
      else if (cyc < 90) begin
      end
      else if (cyc == 99) begin
         $write("[%0t] cyc==%0d crc=%x sum=%x\n", $time, cyc, crc, sum);
         `checkh(crc, 64'hc77bb9b3784ea091);
         // What checksum will we end up with (above print should match)
         `checkh(sum, 64'h4afe43fb79d7b71e);
         $write("*-* All Finished *-*\n");
         $finish;
      end
   end

endmodule

module Test(/*AUTOARG*/
   // Outputs
   out,
   // Inputs
   clk, in
   );

   // Replace this module with the device under test.
   //
   // Change the code in the t module to apply values to the inputs and
   // merge the output values into the result vector.

   input clk;
   input [31:0] in;
   output reg [31:0] out;

   always @(posedge clk) begin
      out <= in;
   end
endmodule