// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2014 Wilson Snyder
// SPDX-License-Identifier: CC0-1.0

// verilog_format: off
`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)
// verilog_format: on

module t (
    input clk
);

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

  generate
    for (genvar width = 1; width <= 16; width++) begin
      for (genvar amt = 1; amt <= width; amt++) begin
        Test #(
            .WIDTH(width),
            .AMT(amt)
        ) test (
            .ins(crc[width-1:0])
        );
      end
    end
  endgenerate

  // Test loop
  always @(posedge clk) begin
`ifdef TEST_VERBOSE
    $write("[%0t] cyc==%0d crc=%x\n", $time, cyc, crc);
`endif
    cyc <= cyc + 1;
    crc <= {crc[62:0], crc[63] ^ crc[2] ^ crc[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
    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'h0
      if (sum !== `EXPECTED_SUM) $stop;
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end

endmodule

module Test (  /*AUTOARG*/
    // Inputs
    ins
);

  parameter WIDTH = 1;
  parameter AMT = 1;

  input [WIDTH-1:0] ins;
  reg [WIDTH-1:0] got;
  reg [WIDTH-1:0] expec;
  int istart;
  int bitn;
  int ostart;

  always @* begin
    got = {<<AMT{ins}};

    // Note always starts with right-most bit
    expec = 0;
    for (istart = 0; istart < WIDTH; istart += AMT) begin
      ostart = WIDTH - AMT - istart;
      if (ostart < 0) ostart = 0;
      for (bitn = 0; bitn < AMT; bitn++) begin
        if ((istart+bitn) < WIDTH
                && (istart+bitn) >= 0
                && (ostart+bitn) < WIDTH
                && (ostart+bitn) >= 0) begin
          expec[ostart+bitn] = ins[istart+bitn];
        end
      end
    end

`ifdef TEST_VERBOSE
    $write("[%0t] exp %0d'b%b got %0d'b%b = { << %0d { %0d'b%b }}\n", $time, WIDTH, expec, WIDTH,
           got, AMT, WIDTH, ins);
`endif
    `checkh(got, expec);
  end

endmodule