(45 . 7)(45 . 7)
   function W_Borrow(A : in Word; B : in Word; D : in Word)
                    return WBool is
   begin
      return WBool(Shift_Right(((not A) and B) or (((not A) or B) and D),
      return WBool(Shift_Right((B and D) or ((B or D) and (not A)),
                               Bitness - 1));
   end W_Borrow;