(* M2StackWord.def provides a generic stack for WORD sized objects.

Copyright (C) 2001-2023 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.

This file is part of GNU Modula-2.

GNU Modula-2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GNU Modula-2 is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Modula-2; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  *)

DEFINITION MODULE M2StackWord ;

(*
    Title      : M2StackWord
    Author     : Gaius Mulley
    System     : UNIX (GNU Modula-2)
    Date       : Fri Oct 12 17:26:50 2001
    Revision   : $Version$
    Description: provides a generic stack for WORD sized objects.
*)

FROM SYSTEM IMPORT WORD ;
EXPORT QUALIFIED StackOfWord, InitStackWord, KillStackWord, PushWord,
                 ReduceWord, RemoveTop, PopWord, PeepWord, IsEmptyWord,
                 NoOfItemsInStackWord ;

TYPE
   StackOfWord ;


(*
   InitStackWord - creates and returns a new stack.
*)

PROCEDURE InitStackWord () : StackOfWord ;


(*
   KillStackWord - destroys a stack, returning NIL.
*)

PROCEDURE KillStackWord (s: StackOfWord) : StackOfWord ;


(*
   PushWord - pushes a word, w, onto, s.
*)

PROCEDURE PushWord (s: StackOfWord; w: WORD) ;


(*
   PopWord - pops an element from stack, s.
*)

PROCEDURE PopWord (s: StackOfWord) : WORD ;


(*
   IsEmptyWord - returns TRUE if stack, s, is empty.
*)

PROCEDURE IsEmptyWord (s: StackOfWord) : BOOLEAN ;


(*
   PeepWord - returns the element at, n, items below in the stack.
              Top of stack can be seen via Peep(s, 1)
*)

PROCEDURE PeepWord (s: StackOfWord; n: CARDINAL) : WORD ;


(*
   ReduceWord - reduce the stack by n elements.
*)

PROCEDURE ReduceWord (s: StackOfWord; n: CARDINAL) ;


(*
   RemoveTop - throw away the top element of the stack.
*)

PROCEDURE RemoveTop (s: StackOfWord) ;


(*
   NoOfItemsInStackWord - returns the number of items held in the stack, s.
*)

PROCEDURE NoOfItemsInStackWord (s: StackOfWord) : CARDINAL ;


END M2StackWord.