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(* FifoQueue.mod provides a simple fifo queue.
Copyright (C) 2001-2025 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/>. *)
IMPLEMENTATION MODULE FifoQueue ;
FROM Lists IMPORT List, InitList, PutItemIntoList, GetItemFromList ;
TYPE
Fifo = RECORD
Queue: List ;
Out : CARDINAL ;
END ;
VAR
const,
subrange,
enumeration,
constructor: Fifo ;
(*
PutInto - places a CARDINAL number, c, into a fifo queue.
*)
PROCEDURE PutInto (VAR f: Fifo; c: CARDINAL) ;
BEGIN
WITH f DO
PutItemIntoList(Queue, c)
END
END PutInto ;
(*
GetFrom - retrieves a CARDINAL number, c, from a fifo queue.
*)
PROCEDURE GetFrom (VAR f: Fifo; VAR c: CARDINAL) ;
BEGIN
WITH f DO
INC(Out) ;
c := GetItemFromList(Queue, Out)
END
END GetFrom ;
(*
PutEnumerationIntoFifoQueue - places an enumeration symbol, c,
into a fifo queue.
*)
PROCEDURE PutEnumerationIntoFifoQueue (c: CARDINAL) ;
BEGIN
PutInto(enumeration, c)
END PutEnumerationIntoFifoQueue ;
(*
GetEnumerationFromFifoQueue - retrieves an enumeration symbol,
c, from a fifo queue.
*)
PROCEDURE GetEnumerationFromFifoQueue (VAR c: CARDINAL) ;
BEGIN
GetFrom(enumeration, c)
END GetEnumerationFromFifoQueue ;
(*
PutSubrangeIntoFifoQueue - places a subrange symbol into a fifo
queue.
*)
PROCEDURE PutSubrangeIntoFifoQueue (c: CARDINAL) ;
BEGIN
PutInto(subrange, c)
END PutSubrangeIntoFifoQueue ;
(*
GetSubrangeFromFifoQueue - retrieves a subrange symbol from a
fifo queue.
*)
PROCEDURE GetSubrangeFromFifoQueue (VAR c: CARDINAL) ;
BEGIN
GetFrom(subrange, c)
END GetSubrangeFromFifoQueue ;
(*
PutConstructorIntoFifoQueue - places a constructor symbol
into a fifo queue.
*)
PROCEDURE PutConstructorIntoFifoQueue (c: CARDINAL) ;
BEGIN
PutInto(constructor, c)
END PutConstructorIntoFifoQueue ;
(*
GetConstructorFromFifoQueue - retrieves a constructor symbol
from a fifo queue.
*)
PROCEDURE GetConstructorFromFifoQueue (VAR c: CARDINAL) ;
BEGIN
GetFrom(constructor, c)
END GetConstructorFromFifoQueue ;
(*
PutConstIntoFifoQueue - places a constant symbol
into a fifo queue.
*)
PROCEDURE PutConstIntoFifoQueue (c: CARDINAL) ;
BEGIN
PutInto(const, c)
END PutConstIntoFifoQueue ;
(*
GetConstFromFifoQueue - retrieves a const symbol
from a fifo queue.
*)
PROCEDURE GetConstFromFifoQueue (VAR c: CARDINAL) ;
BEGIN
GetFrom(const, c)
END GetConstFromFifoQueue ;
(*
Init - initialize the fifo queue.
*)
PROCEDURE Init (VAR f: Fifo) ;
BEGIN
WITH f DO
InitList(Queue) ;
Out := 0
END
END Init ;
BEGIN
Init(const) ;
Init(enumeration) ;
Init(subrange) ;
Init(constructor)
END FifoQueue.
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