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(* RTdata.mod implements a mechanism whereby devices can attach data.
Copyright (C) 2008-2023 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. *)
IMPLEMENTATION MODULE RTdata ;
FROM IOLink IMPORT RAISEdevException ;
FROM RTentity IMPORT Group, InitGroup, PutKey, IsIn, DelKey ;
FROM Storage IMPORT ALLOCATE, DEALLOCATE ;
IMPORT IOChan ;
TYPE
key = (allocated, deallocated) ;
(* each module can register one of these *)
ModuleId = POINTER TO RECORD
id: CARDINAL ;
END ;
(* each device can contain multiple of the these *)
ModuleData = POINTER TO RECORD
mid : ModuleId ;
data : ADDRESS ;
free : FreeProcedure ;
right: ModuleData ;
END ;
(*
MakeModuleId - creates a unique module Id.
*)
PROCEDURE MakeModuleId (VAR m: ModuleId) ;
BEGIN
INC(lastId) ;
NEW(m) ;
WITH m^ DO
id := lastId
END ;
PutKey(mids, m, ORD(allocated))
END MakeModuleId ;
(*
verifyModuleId - verifies that, m, has not been deallocated.
*)
PROCEDURE verifyModuleId (m: ModuleId; d: DeviceTablePtr) ;
BEGIN
IF NOT IsIn(mids, m)
THEN
WITH d^ DO
RAISEdevException(cid, did, IOChan.hardDeviceError,
'RTdata: invalid module id')
END
END
END verifyModuleId ;
(*
InitData - adds, datum, to the device, d. The datum
is associated with ModuleID, m.
*)
PROCEDURE InitData (d: DeviceTablePtr; m: ModuleId;
datum: ADDRESS; f: FreeProcedure) ;
VAR
md: ModuleData ;
BEGIN
NEW(md) ;
WITH md^ DO
mid := m ;
data := datum ;
free := f ;
right := d^.cd
END ;
d^.cd := md
END InitData ;
(*
GetData - returns the datum assocated with ModuleId, m.
*)
PROCEDURE GetData (d: DeviceTablePtr; m: ModuleId) : ADDRESS ;
VAR
md: ModuleData ;
BEGIN
verifyModuleId(m, d) ;
md := d^.cd ;
WHILE md#NIL DO
IF md^.mid=m
THEN
RETURN( md^.data )
ELSE
md := md^.right
END
END ;
RETURN( md )
END GetData ;
(*
KillData - destroys the datum associated with ModuleId, m,
in device, d. It invokes the free procedure
given during InitData.
*)
PROCEDURE KillData (d: DeviceTablePtr; m: ModuleId) ;
VAR
last,
md : ModuleData ;
BEGIN
verifyModuleId(m, d) ;
last := NIL ;
md := d^.cd ;
WHILE md#NIL DO
IF md^.mid=m
THEN
IF last=NIL
THEN
d^.cd := md^.right
ELSE
last^.right := md^.right
END ;
DelKey(mids, m) ;
md^.free(md^.data) ;
md^.data := NIL ;
DISPOSE(md)
ELSE
last := md ;
md := md^.right
END
END
END KillData ;
VAR
mids : Group ;
lastId: CARDINAL ;
BEGIN
mids := InitGroup() ;
lastId := 0
END RTdata.
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