`timescale 1ns / 1ps

module testbench();

  reg reset = 0;
  
  initial begin
    $dumpfile("testbench.vcd");
    $dumpvars(0,testbench);
  end

  reg clk = 0;
  always #32 clk = !clk;


  reg [31:0] a, b, exp_result;
  reg [3:0] op;
  reg [3:0] exp_flags;
  wire [31:0] result;
  wire zero, exp_zero;

  assign exp_zero = exp_flags[0];

  reg [31:0]	vector_count, error_count;
  reg [103:0] testvec [0:9999];

  initial begin
    $readmemh("alu_testvec.txt", testvec);
    error_count = 0;
    vector_count = 0;
  end
  
  always @ (posedge clk) begin
    #16;
    {op, a, b, exp_result, exp_flags} = testvec[vector_count];
    #32;
    if ((result !== exp_result) | (zero !== exp_zero)) begin
      $display("Error at %5d ns: op %b a = %h b = %h", $time, op, a, b);
      $display("       %h (expected %h)", result, exp_result);
      $display(" zero: %b (expected %b)", zero, exp_zero);

      error_count = error_count + 1;
    end

    vector_count = vector_count + 1;

    if ((vector_count == 9027)) begin
      $display("%d tests completed with %d errors", vector_count, error_count);
      #16;

      $finish;
    end
  end

  
  

  alu #(.N(32)) alu (
    .A(a),
    .B(b),
    .OP(op),
    .RESULT(result),
    .ZERO(zero)
  );

endmodule