package body Logic is

   --  @name Step
   --  @return
   --  @parameter N:Natural
   --  @parameter O:Natural
   --  @description Do one calculation step and safe the result to O.
   procedure Step (N : Natural; O : out Natural) is

   begin

      if N mod 2 = 0 then
         O := N / 2;
      else
         O := 3 * N + 1;
      end if;

   end Step;

   --  @name Row
   --  @return
   --  @parameter N:Natural,Final
   --  @description Calculate full row for design.
   procedure Row (N : Natural; Final : out Natural) is
      Old    : Natural := N;
      Update : Natural;
   begin

      while (Old < (Natural'Last / 3)) and (not (Old = 1)) loop

         Step (Old, Update);
         Old := Update;

      end loop;

      if not (Old = 1) then
         Old := 1;
      end if;

      Final := Old;

   end Row;

end Logic;