// Enabling IRQ's (extended mode)
    write_register(8'd4, 8'hff);


    fork
      begin
        #2700;
        $display("\n\nStart receiving data from CAN bus");
        /* Standard frame format
        receive_frame(0, 0, {26'h00000a0, 3'h1}, 4'h1, 15'h2d9c); // mode, rtr, id, length, crc
        receive_frame(0, 0, {26'h00000a0, 3'h1}, 4'h2, 15'h46b4); // mode, rtr, id, length, crc
        receive_frame(0, 0, {26'h00000af, 3'h1}, 4'h0, 15'h42cd); // mode, rtr, id, length, crc
        receive_frame(0, 0, {26'h00000af, 3'h1}, 4'h1, 15'h555f); // mode, rtr, id, length, crc
        receive_frame(0, 0, {26'h00000af, 3'h1}, 4'h2, 15'h6742); // mode, rtr, id, length, crc
        */

        // Extended frame format
        receive_frame(1, 0, {8'ha6, 8'h00, 8'h5a, 5'h15}, 4'h1, 15'h2d22); // mode, rtr, id, length, crc
        receive_frame(1, 0, {8'ha6, 8'h00, 8'h5a, 5'h15}, 4'h2, 15'h3d2d); // mode, rtr, id, length, crc
        receive_frame(1, 0, {8'ha6, 8'h00, 8'h5a, 5'h15}, 4'h0, 15'h23aa); // mode, rtr, id, length, crc
        receive_frame(1, 0, {8'ha6, 8'h00, 8'h5a, 5'h15}, 4'h1, 15'h2d22); // mode, rtr, id, length, crc
        receive_frame(1, 0, {8'ha6, 8'h00, 8'h5a, 5'h15}, 4'h2, 15'h3d2d); // mode, rtr, id, length, crc

      end

      begin
        tx_request_command;
      end

      begin
        // Transmitting acknowledge
        wait (can_testbench.i_can_top.i_can_bsp.tx_state & can_testbench.i_can_top.i_can_bsp.rx_ack);
        #1 rx = 0;
        wait (can_testbench.i_can_top.i_can_bsp.rx_ack_lim);
        #1 rx = 1;
      end

      begin   // Reading irq and arbitration lost capture register

        repeat(1)
          begin
            while (~(can_testbench.i_can_top.i_can_bsp.rx_crc_lim & can_testbench.i_can_top.i_can_bsp.sample_point))
              begin
                @ (posedge clk);
              end

            // Read irq register
            #1 read_register(8'd3);
    
            // Read arbitration lost capture register
            read_register(8'd11);
          end


        repeat(1)
          begin
            while (~(can_testbench.i_can_top.i_can_bsp.rx_crc_lim & can_testbench.i_can_top.i_can_bsp.sample_point))
              begin
                @ (posedge clk);
              end

            // Read irq register
            #1 read_register(8'd3);
          end

        repeat(1)
          begin
            while (~(can_testbench.i_can_top.i_can_bsp.rx_crc_lim & can_testbench.i_can_top.i_can_bsp.sample_point))
              begin
                @ (posedge clk);
              end

            // Read arbitration lost capture register
            read_register(8'd11);
          end

      end

    join

    read_receive_buffer;
    release_rx_buffer_command;
    release_rx_buffer_command;
    read_receive_buffer;
    release_rx_buffer_command;
    read_receive_buffer;
    release_rx_buffer_command;
    read_receive_buffer;
    release_rx_buffer_command;
    read_receive_buffer;

    #200000;

    read_receive_buffer;

    // Read irq register
    read_register(8'd3);
    #1000;

  end
endtask   // send_frame_extended



task self_reception_request;    // CAN IP core sends sets self reception mode and transmits a msg. This test runs in EXTENDED mode
  begin

    // Switch-on reset mode
    write_register(8'd0, {7'h0, (`CAN_MODE_RESET)});
    
    // Set Clock Divider register
    extended_mode = 1'b1;
    write_register(8'd31, {extended_mode, 7'h0});    // Setting the extended mode
 
    // Set Acceptance Code and Acceptance Mask registers
    write_register(8'd16, 8'ha6); // acceptance code 0
    write_register(8'd17, 8'hb0); // acceptance code 1
    write_register(8'd18, 8'h12); // acceptance code 2
    write_register(8'd19, 8'h30); // acceptance code 3
    write_register(8'd20, 8'h00); // acceptance mask 0
    write_register(8'd21, 8'h00); // acceptance mask 1
    write_register(8'd22, 8'h00); // acceptance mask 2
    write_register(8'd23, 8'h00); // acceptance mask 3

    // Setting the "self test mode"
    write_register(8'd0, 8'h4);

    // Switch-off reset mode
    write_register(8'd0, {7'h0, ~(`CAN_MODE_RESET)});

    // After exiting the reset mode sending bus free
    repeat (11) send_bit(1);


    // Writing TX frame information + identifier + data
    write_register(8'd16, 8'h45);   // Frame format = 0, Remote transmision request = 1, DLC = 5
    write_register(8'd17, 8'ha6);   // ID[28:21] = a6
    write_register(8'd18, 8'ha0);   // ID[20:18] = 5
    // write_register(8'd19, 8'h78); RTR does not send any data
    // write_register(8'd20, 8'h9a);
    // write_register(8'd21, 8'hbc);
    // write_register(8'd22, 8'hde);
    // write_register(8'd23, 8'hf0);
    // write_register(8'd24, 8'h0f);
    // write_register(8'd25, 8'hed);
    // write_register(8'd26, 8'hcb);
    // write_register(8'd27, 8'ha9);
    // write_register(8'd28, 8'h87);


    // Enabling IRQ's (extended mode)
    write_register(8'd4, 8'hff);

    self_reception_request_command;

    #400000;

    read_receive_buffer;
    release_rx_buffer_command;
    release_rx_buffer_command;
    read_receive_buffer;
    release_rx_buffer_command;
    read_receive_buffer;
    release_rx_buffer_command;
    read_receive_buffer;
    release_rx_buffer_command;
    read_receive_buffer;


    read_receive_buffer;

    // Read irq register
    read_register(8'd3);
    #1000;

  end
endtask   // self_reception_request



task test_empty_fifo;
  begin

    // Enable irqs (basic mode)
    write_register(8'd0, 8'h1e);

    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h3, 15'h56a9); // mode, rtr, id, length, crc
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h7, 15'h391d); // mode, rtr, id, length, crc

    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h8, 15'h70e0); // mode, rtr, id, length, crc

    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;
  end
endtask



task test_empty_fifo_ext;
  begin
    receive_frame(1, 0, 29'h14d60246, 4'h3, 15'h5262); // mode, rtr, id, length, crc
    receive_frame(1, 0, 29'h14d60246, 4'h7, 15'h1730); // mode, rtr, id, length, crc
    
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    receive_frame(1, 0, 29'h14d60246, 4'h8, 15'h2f7a); // mode, rtr, id, length, crc

    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;
  end
endtask



task test_full_fifo;
  begin

    // Enable irqs (basic mode)
    write_register(8'd0, 8'h1e);

    $display("\n\n");

    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h0, 15'h2372); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h1, 15'h30bb); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h2, 15'h2da1); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h3, 15'h56a9); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h4, 15'h3124); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h5, 15'h6944); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h6, 15'h5182); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h7, 15'h391d); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h8, 15'h70e0); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h8, 15'h70e0); // mode, rtr, id, length, crc
    fifo_info;
    $display("FIFO should be full now");

    // Following one is accepted with overrun
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h8, 15'h70e0); // mode, rtr, id, length, crc
    fifo_info;

    release_rx_buffer_command;
    fifo_info;

    // Space just enough for the following frame.
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h0, 15'h2372); // mode, rtr, id, length, crc
    fifo_info;

    // Following accepted with overrun
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h8, 15'h70e0); // mode, rtr, id, length, crc
    fifo_info;
//    read_overrun_info(0, 15);

    release_rx_buffer_command;
    release_rx_buffer_command;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;
    receive_frame(0, 0, {26'h00000e8, 3'h1}, 4'h8, 15'h70e0); // mode, rtr, id, length, crc
    fifo_info;
//    read_overrun_info(0, 15);
    $display("\n\n");

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    clear_data_overrun_command;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    clear_data_overrun_command;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    // Read irq register
    read_register(8'd3);

    // Read irq register
    read_register(8'd3);
    #1000;

  end
endtask



task test_full_fifo_ext;
  begin
    release_rx_buffer_command;
    $display("\n\n");
    read_receive_buffer;
    fifo_info;

    receive_frame(1, 0, 29'h14d60246, 4'h0, 15'h6f54); // mode, rtr, id, length, crc
    read_receive_buffer;
    fifo_info;
    receive_frame(1, 0, 29'h14d60246, 4'h1, 15'h6d38); // mode, rtr, id, length, crc
    read_receive_buffer;
    fifo_info;
    receive_frame(1, 0, 29'h14d60246, 4'h2, 15'h053e); // mode, rtr, id, length, crc
    fifo_info;
    read_receive_buffer;
    receive_frame(1, 0, 29'h14d60246, 4'h3, 15'h5262); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(1, 0, 29'h14d60246, 4'h4, 15'h4bba); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(1, 0, 29'h14d60246, 4'h5, 15'h4d7d); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(1, 0, 29'h14d60246, 4'h6, 15'h6f40); // mode, rtr, id, length, crc
    fifo_info;
    receive_frame(1, 0, 29'h14d60246, 4'h7, 15'h1730); // mode, rtr, id, length, crc
    fifo_info;
//    read_overrun_info(0, 10);

    release_rx_buffer_command;
    release_rx_buffer_command;
    fifo_info;
    receive_frame(1, 0, 29'h14d60246, 4'h8, 15'h2f7a); // mode, rtr, id, length, crc
    fifo_info;
//    read_overrun_info(0, 15);
    $display("\n\n");

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

    release_rx_buffer_command;
    read_receive_buffer;
    fifo_info;

  end
endtask


/*
task initialize_fifo;
  integer i;
  begin
    for (i=0; i<32; i=i+1)
      begin
        can_testbench.i_can_top.i_can_bsp.i_can_fifo.length_info[i] = 0;
        can_testbench.i_can_top.i_can_bsp.i_can_fifo.overrun_info[i] = 0;