/*

* Copyright (c) 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:   Declaration of the RWlanLddCircularBuffer class.

*

*/

/*

* %version: 2 %

*/

#ifndef R_WLANCIRCULARBUFFER_H

#define R_WLANCIRCULARBUFFER_H

class TDataBuffer;

/**

 * Wlan LDD Shared Memory FIFO queue for Tx packets.

 * 

 * @param size The size of the queue in packets.

 */

template <TUint size>

class RWlanCircularBuffer

    {

public:

    /* Because this class is mapped into shared memory, it does not have

     * a constructor or a desctructor.

     */ 

    /**

     * Initialization. This method acts as a contructor.

     */ 

    inline void DoInit();

    /**

     * Release. This method acts as a desctructor.

     */ 

    inline void Release();

    /**

     * This method returns and removes the next packet from the queue.

     * 

     * @return Pointer to the meta header attached to the packet on success.

     *         NULL if the queue is empty.

     */ 

    inline TDataBuffer* GetPacket();

    /**

     * This method is used to put a packet to the end of the queue.

     * 

     * @param aPacket Pointer to the meta header attached to the packet.

     * @return ETrue if the Packet was added to the queue.

     *         EFalse if the queue was already full and the Packet could not

     *         be added to the queue.

     */ 

    inline TBool PutPacket( TDataBuffer* aPacket );

    /**

     * Returns the next packet in the queue without removing it from the queue.

     * 

     * @return Pointer to the meta header attached to the packet on the top 

     *         of the queue.

     */

    inline TDataBuffer* PeekPacket();

    /**

     * Returns the number of packets in the queue.

     * 

     * @return number of packets in the queue.

     */

    inline TUint GetLength() const;

    /**

     * This method can be used to check if the queue is empty.

     * 

     * @return ETrue, when the queue is empty.

     *         EFalse, when the queue is not empty.

     */ 

    inline TBool IsEmpty() const;

    /**

     * This method can be used to check if the queue is full.

     * 

     * @return ETrue, when the queue is full.

     *         EFalse, when the queue is not full.

     */ 

    inline TBool IsFull() const ;

    /**

     * This method can be used to check if the queue is active.

     * 

     * @param aTimeNow Current time as microseconds since midnight, January 

     *        1st, 0 AD nominal Gregorian

     * @return ETrue, if the queue is active.

     *         EFalse, if the queue is not active.

     */ 

    inline TBool IsActive( TInt64 aTimeNow ) const;

private:    // Data

    /** Queue as a circular buffer */

    TDataBuffer* iBuffer[size];

    /** Index of the packet to get next. See GetPacket() */

    TUint iGetIndex;

    /** Index where to put the next packet. See PutPacket() */

    TUint iPutIndex;

    /** The number of packets currently in the queue */

    TUint iPacketAmount;

    /** The capacity of the queue */

    TUint iSize;

    /** 

    * Time stamp (as microseconds since midnight, January 1st, 0 AD nominal

    * Gregorian) when the queue became empty. 

    * Valid only if the queue is empty 

    */

    TInt64 iBecameEmptyAt;

};

#ifdef __KERNEL_MODE__

#include "wllddcircularbuffer.inl"

#endif

#endif /* R_WLANCIRCULARBUFFER_H */