// Copyright (c) 2002-2009 Nokia Corporation and/or its subsidiary(-ies).

 // All rights reserved.

 // This component and the accompanying materials are made available

 // under the terms of the License "Eclipse Public License v1.0"

 // which accompanies this distribution, and is available

 // at the URL "http://www.eclipse.org/legal/epl-v10.html".

 //

 // Initial Contributors:

 // Nokia Corporation - initial contribution.

 //

 // Contributors:

 //

 // Description:

 // e32\include\kernel\msgqueue.h

 // 

 //

 #ifndef __MSGQUEUE_H__

 #define __MSGQUEUE_H__

 #include <kernel/kernel.h>

 #include "nk_priv.h"

 /**

 @internalComponent

 */

 class DMsgQueue : public DObject

 	{

 public:

 	enum TQueueState {EEmpty, EPartial, EFull};

 	enum {KMaxLength = 256};

 public:

 	~DMsgQueue();

 	TInt Create(DObject* aOwner, const TDesC* aName, TInt aMsgLength, TInt aSlotCount, TBool aVisible = ETrue);

 	TInt Send(const TAny* aPtr, TInt aLength);

 	TInt Receive(TAny* aPtr, TInt aLength);

 	void NotifySpaceAvailable(TRequestStatus* aStatus);

 	void NotifyDataAvailable(TRequestStatus* aStatus);

 	void CancelSpaceAvailable();

 	void CancelDataAvailable();

 	TInt MessageSize() const;

 private:

 	enum TNotification {ESpaceAvailable, EDataAvailable};

 	void CompleteRequestIfPending(DThread*& aThread, TClientRequest* aRequest, TInt aCompletionVal);

 	void RequestNotification(TNotification aNotification, TRequestStatus* aStatus, DThread*& aThread, TClientRequest* aRequest);

 private:

 	TUint8* iMsgPool;			//pointer to the block of memory used for the slots

 	TUint8* iFirstFreeSlot;		//first free slot in the msg pool unless iState == EFull

 	TUint8* iFirstFullSlot;		//first full slot in the pool unless iState == EEmpty

 	TUint8* iEndOfPool;			//address after the allocated pool.  

 	DThread* iThreadWaitingOnSpaceAvail;	//thread waiting for space available notification

 	DThread* iThreadWaitingOnDataAvail;		//thread waiting for data available notification

 	TClientRequest* iDataAvailRequest;

 	TClientRequest* iSpaceAvailRequest;

 	TUint16 iMaxMsgLength;		//max message length in bytes

 	TUint8 iState;				//whether the queue is empty, full or in between

 	TUint8 iSpare;

 public:

 	friend class Monitor;

 	};

 #endif