// 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