IMPLEMENTATION MODULE Stack ;

FROM Memory IMPORT WriteSlot, ReadSlot ;
FROM Local IMPORT GetSP, SetSP ;

TYPE
  RealView = RECORD CASE : BOOLEAN OF
               | TRUE: r : REAL ;
               | FALSE: v : LONGCARD ;
             END ;
           END ;
  QuadView = RECORD CASE : BOOLEAN OF
               | TRUE: r : LONGREAL ;
               | FALSE: lo, hi : LONGCARD ;
             END ;
           END ;

VAR
  rv : RealView ;
  qv : QuadView ;

PROCEDURE Push (v: LONGCARD) ;
BEGIN
  SetSP (GetSP () - 8) ;
  WriteSlot (GetSP (), v) ;
END Push ;

PROCEDURE Pop () : LONGCARD ;
VAR v: LONGCARD ;
BEGIN
  v := ReadSlot (GetSP ()) ;
  SetSP (GetSP () + 8) ;
  RETURN v ;
END Pop ;

PROCEDURE PushInt (v: INTEGER) ;
BEGIN
  Push (VAL (LONGCARD, v)) ;
END PushInt ;

PROCEDURE PopInt () : INTEGER ;
BEGIN
  RETURN VAL (INTEGER, VAL (CARDINAL, Pop ())) ;
END PopInt ;

PROCEDURE PushCard (v: CARDINAL) ;
BEGIN
  Push (VAL (LONGCARD, v)) ;
END PushCard ;

PROCEDURE PopCard () : CARDINAL ;
BEGIN
  RETURN VAL (CARDINAL, Pop ()) ;
END PopCard ;

PROCEDURE PushBool (v: BOOLEAN) ;
BEGIN
  IF v THEN
    Push (1) ;
  ELSE
    Push (0) ;
  END ;
END PushBool ;

PROCEDURE PopBool () : BOOLEAN ;
BEGIN
  RETURN Pop () # 0 ;
END PopBool ;

PROCEDURE PushLongInt (v: LONGINT) ;
BEGIN
  Push (VAL (LONGCARD, v)) ;
END PushLongInt ;

PROCEDURE PopLongInt () : LONGINT ;
BEGIN
  RETURN VAL (LONGINT, Pop ()) ;
END PopLongInt ;

PROCEDURE PushLongCard (v: LONGCARD) ;
BEGIN
  Push (v) ;
END PushLongCard ;

PROCEDURE PopLongCard () : LONGCARD ;
BEGIN
  RETURN Pop () ;
END PopLongCard ;

PROCEDURE PushReal (v: REAL) ;
BEGIN
  rv.r := v ;
  Push (rv.v) ;
END PushReal ;

PROCEDURE PopReal () : REAL ;
BEGIN
  rv.v := Pop () ;
  RETURN rv.r ;
END PopReal ;

PROCEDURE PushQuad (v: LONGREAL) ;
BEGIN
  qv.r := v ;
  Push (qv.hi) ;
  Push (qv.lo) ;
END PushQuad ;

PROCEDURE PopQuad () : LONGREAL ;
BEGIN
  qv.lo := Pop () ;
  qv.hi := Pop () ;
  RETURN qv.r ;
END PopQuad ;

PROCEDURE Reserve (n: CARDINAL) ;
BEGIN
  SetSP (GetSP () - VAL (LONGCARD, n) * 8) ;
END Reserve ;

END Stack.