// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2011 Wilson Snyder
// SPDX-License-Identifier: CC0-1.0

module t (
    input clk
);

  integer cyc = 0;
  reg [63:0] crc;
  reg [63:0] sum;

  parameter DW = 4;
  wire [3:0] drv_a = crc[3:0];
  wire [3:0] drv_b = crc[7:4];
  wire [3:0] drv_e = crc[19:16];

  /*AUTOWIRE*/
  // Beginning of automatic wires (for undeclared instantiated-module outputs)
  wire [DW-1:0] drv;  // To/From test1 of Test1.v
  wire [DW-1:0] drv2;  // From test2 of Test2.v
  // End of automatics

  Test1 test1 (  /*AUTOINST*/
      // Inouts
      .drv(drv[DW-1:0]),
      // Inputs
      .drv_a(drv_a[DW-1:0]),
      .drv_b(drv_b[DW-1:0]),
      .drv_e(drv_e[DW-1:0])
  );
  Test2 test2 (  /*AUTOINST*/
      // Outputs
      .drv2(drv2[DW-1:0]),
      // Inputs
      .drv_a(drv_a[DW-1:0]),
      .drv_b(drv_b[DW-1:0]),
      .drv_e(drv_e[DW-1:0])
  );

  // Aggregate outputs into a single result vector
  wire [63:0] result = {60'h0, drv};

  // Test loop
  always @(posedge clk) begin
`ifdef TEST_VERBOSE
    $write("[%0t] cyc==%0d crc=%x drv=%x %x  (%b??%b:%b)\n", $time, cyc, crc, drv, drv2, drv_e,
           drv_a, drv_b);
`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 <= 64'h0;
    end
    else if (cyc < 10) begin
      sum <= 64'h0;
    end
    else if (cyc < 90) begin
      if (drv2 != drv) $stop;
    end
    else if (cyc == 99) begin
      $write("[%0t] cyc==%0d crc=%x sum=%x\n", $time, cyc, crc, sum);
      if (crc !== 64'hc77bb9b3784ea091) $stop;
      // What checksum will we end up with (above print should match)
      `define EXPECTED_SUM 64'hd95d216c5a2945d0
      if (sum !== `EXPECTED_SUM) $stop;
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end

endmodule

module Test1 #(
    parameter DW = 4
) (
    input wire [DW-1:0] drv_a,
    input wire [DW-1:0] drv_b,
    input wire [DW-1:0] drv_e,
    inout wire [DW-1:0] drv
);

  wire drv_0, drv_1, drv_2, drv_3;
  bufif1 bufa0 (drv_0, drv_a[0], drv_e[0]);
  bufif1 bufb0 (drv_0, drv_b[0], ~drv_e[0]);
  bufif1 bufa1 (drv_1, drv_a[1], drv_e[1]);
  bufif1 bufb1 (drv_1, drv_b[1], ~drv_e[1]);
  bufif1 bufa2 (drv_2, drv_a[2], drv_e[2]);
  bufif1 bufb2 (drv_2, drv_b[2], ~drv_e[2]);
  bufif1 bufa3 (drv_3, drv_a[3], drv_e[3]), bufb3 (drv_3, drv_b[3], ~drv_e[3]);
  assign drv = {drv_3, drv_2, drv_1, drv_0};

endmodule

module Test2 #(
    parameter DW = 4
) (
    input wire [DW-1:0] drv_a,
    input wire [DW-1:0] drv_b,
    input wire [DW-1:0] drv_e,
    inout wire [DW-1:0] drv2
);

  wire [DW-1:0] drv_all;
  bufif1 bufa[DW-1:0] (drv_all, drv_a, drv_e);
  // Below ~= bufif1 bufb [DW-1:0] (drv_all, drv_b, ~drv_e);
  bufif1 bufb[DW-1:0] (
      {drv_all[3], drv_all[2], drv_all[1], drv_all[0]},
      {drv_b[3], drv_b[2], drv_b[1], drv_b[0]},
      {~drv_e[3], ~drv_e[2], ~drv_e[1], ~drv_e[0]}
  );
  assign drv2 = drv_all;

endmodule