ALU TB

`timescale 1ns/10ps

typedef enum bit[3:0] {ADD, SUB, MUL, DIV, MOD, POW,
                       AND,  OR, XOR,
                       CONC,
                       LLS, LRS,
                       ALS, ARS,
                       GTQ, EQU} opcode_enum;

class alu_inputs;
  rand bit [3:0] a_rand, b_rand;
  rand opcode_enum opcode_rand;
  constraint opcode_range
  {
    (opcode_rand == POW) -> b_rand inside {[0:2]};
  }
endclass

module alu_tb();



reg  [3:0] a_tb, b_tb;
reg        rst_tb, clk_tb;
reg  [3:0] opcode_tb;
wire [7:0] _output_tb;

always
begin
  clk_tb = 1'b1; #(10);
  clk_tb = 1'b0; #(10);
end

alu uut(.a(a_tb), .b(b_tb), .clk(clk_tb), .rst(rst_tb), .opcode(opcode_tb), ._output(_output_tb));

alu_inputs alu_rand;

integer i;

initial
begin
  alu_rand = new();
  rst_tb = 1;
  @(negedge clk_tb);
  rst_tb = 0;
  @(negedge clk_tb);
  for (i = 0; i < 50; i = i + 1)
  begin
    alu_rand.randomize();
    opcode_tb = alu_rand.opcode_rand;
    a_tb = alu_rand.a_rand;
    b_tb = alu_rand.b_rand;
    @(negedge clk_tb);
  end
  $stop;
end

/*task check_result(input [7:0] exp_rslt);
  if(exp_rslt !== _output_tb)
    $display("Incorrect");
  else
    $display("Correct");
endtask*/

endmodule