The Toggle_Button3 a State Machine which controlled by the "Button" input and removes eventually bouncing from the contact with a 4-bit shiftregister (not part of the State Machine).

The six internal states produces three outputs:
      Toggle:  Changes state for each press of the button.
      Deboun:  Will be "1" when the button pressed or else "0" (Debouched button)
      Pulse:      Like Deboun but will only be "1" for one Clk period after a press.