package Queue_Pack_Simple is

type Element is new Positive range 1_000 .. 40_000;

type Marker is mod Queue_Size;

type List is array (Marker) of Element;

type Queue_Type is record
      Top, Free : Marker  := Marker'First;
      Is_Empty  : Boolean := True;
      Elements  : List; -- will be initialized to invalids
   end record;

Queue_Size : constant Positive := 10;

procedure Enqueue 
(
Item
:     Element;
Queue
: in out Queue_Type);

procedure Dequeue 
(
Item
: out Element;
Queue
: in out Queue_Type);

function Is_Empty 
(
Queue
: Queue_Type) return Boolean is (Queue.Is_Empty);

function Is_Full 
(
Queue
: Queue_Type) return Boolean is (not Queue.Is_Empty and then Queue.Top = Queue.Free);