//////////////////////////////////////////
// Modular Design #2

module modular_2 (  clk,
                    reset,
                    go_1,
                    kill_1,
                    go_2,
                    kill_2,
                    go_3,
                    kill_3,
                    kill_clr,
                    done_out,
                    kill_ltchd
                 );          

    input          clk;
    input          reset;
    input          go_1;
    input          kill_1;
    input          go_2;
    input          kill_2;
    input          go_3;
    input          kill_3;
    input          kill_clr;
    
    output         done_out;
    output         kill_ltchd;

    reg            kill_ltchd;
    wire           done_1;
    wire           done_2;

    // ------ Design implementation -----

    // first module instantiation
    state_machine_1 go_delay_1
           (
             .reset   ( reset  ),
             .clk     ( clk    ),
             .go      ( go_1   ),
             .kill    ( kill_1 ),
             .done    ( done_1 )
           );

    // second module instantiation
    state_machine_1 go_delay_2
           (
             .reset   ( reset  ),
             .clk     ( clk    ),
             .go      ( done_1 | go_2 ),
             .kill    ( kill_2 ),
             .done    ( done_2 )
           );

    // third module instantiation
    state_machine_1 go_delay_3
           (
             .reset   ( reset    ),
             .clk     ( clk      ),
             .go      (   done_1 
                        | done_2
                        | go_3
                      ),
             .kill    ( kill_3   ),
             .done    ( done_out )
           );


    // Kill Latch
    always @( posedge clk or posedge reset )
      begin
        if ( reset )
          kill_ltchd <= 1'b0;
        else if (   kill_1
                 || kill_2
                 || kill_3
                )
          kill_ltchd <= 1'b1;
        else if ( kill_clr )
          kill_ltchd <= 1'b0;
      end

endmodule