IMPLEMENTATION MODULE RedOpsl1;
FROM QueueInfo IMPORT Maxqueue,InfoTip;

PROCEDURE MakeNull(VAR q : RedOpslTip);
BEGIN
  WITH q DO
    Prvi := 0;
    Zadnji := 0
  END
END MakeNull;

PROCEDURE Empty(VAR q : RedOpslTip) : BOOLEAN;
BEGIN
  RETURN q.Zadnji = 0
END Empty;


PROCEDURE First(VAR q : RedOpslTip;
                VAR x : InfoTip;
                VAR ok : BOOLEAN);
BEGIN
  IF Empty(q) THEN
    ok := FALSE
  ELSE
    ok := TRUE;
    WITH q DO
      x := Element[Prvi]
    END
  END
END First;

PROCEDURE AddOne(i : CARDINAL) : CARDINAL;
BEGIN
  IF i = Maxqueue THEN
    RETURN 1
  ELSE
    RETURN i+1
  END
END AddOne;

PROCEDURE PopFirst(VAR q : RedOpslTip;
                   VAR ok : BOOLEAN);
BEGIN
  IF Empty(q) THEN
    ok := FALSE
  ELSE
    ok := TRUE;
    WITH q DO
      IF Prvi = Zadnji THEN
        MakeNull(q)
      ELSE
        Prvi := AddOne(Prvi)
      END
    END
  END
END PopFirst;

PROCEDURE AddRear(VAR q : RedOpslTip;
                  x : InfoTip;
                  VAR ok : BOOLEAN);
BEGIN
  WITH q DO
    IF AddOne(Zadnji) = Prvi THEN
      ok := FALSE
    ELSE
      ok := TRUE;
      IF Empty(q) THEN
        Prvi := 1;
        Zadnji := 1
      ELSE
        Zadnji := AddOne(Zadnji)
      END;
      Element[Zadnji] := x
    END
  END
END AddRear;

END RedOpsl1.