* %version: 13 %

        iUserToKernAddrOffset( 0 ),

        TDataBuffer*& aBufferStart, 

    * To be called when user mode client issues a frame Rx request

    * @return ETrue if callee should complete the request immediately 

    *         as there exists Rx frame(s) which can be retrieved by the user

    *         mode client.

    *         EFalse otherwise

    virtual TBool OnReadRequest();

     * From DEthernetFrameMemMngr

     * Gets the highest priority frame (contained in a buffer allocated from

     * the shared memory) from the Rx queues.

     * Optionally frees the memory associated to a previously received frame. 

     * 

     * @param aFrameToFreeInUserSpace User space pointer to previously 

     *        received frame which can now be freed.

     *        NULL if nothing to free.

     * @return User space pointer to the Rx frame to be handled next.

     *         NULL, if there are no frames available.

     */ 

    virtual TDataBuffer* GetRxFrame( TDataBuffer* aFrameToFreeInUserSpace );

     * @return User space pointer to the meta header attached to the 

     *         allocated packet, on success.

     * Adds the specified Tx frame (contained in the buffer allocated from the 

     * shared memory) to the relevant Tx queue according to its AC (i.e.

     * priority).

     *  

     * @param aPacketInUserSpace Meta header attached to the frame; as a user

     *        space pointer.

     * @param aPacketInKernSpace If not NULL on return, the frame needs to be 

     *        discarded and this is the kernel space pointer to its meta header.

     *        If NULL on return, the frame must not be discarded. 

     * @param aUserDataTxEnabled ETrue if user data Tx is enabled

     *        EFalse otherwise

     * @return ETrue if the client is allowed to continue calling this method

     *         (i.e. Tx flow is not stopped).

     *         EFalse if the client is not allowed to call this method again

     *         (i.e. Tx flow is stopped) until it is re-allowed.

     */

    virtual TBool AddTxFrame( 

        TDataBuffer* aPacketInUserSpace, 

        TDataBuffer*& aPacketInKernSpace,

        TBool aUserDataTxEnabled );

    /**

     * From DEthernetFrameMemMngr

     * Gets the frame to be transmitted next from the Tx queues.

     * 

     * @param aWhaTxQueueState State (full / not full) of every WHA transmit 

     *        queue

     * @param aMore On return is ETrue if another frame is also ready to be 

     *        transmitted, EFalse otherwise

     * @return Pointer to the meta header of the frame to be transmitted, on

     *         success

     *         NULL, if there's no frame that could be transmitted, given the

     *         current status of the WHA Tx queues

     */ 

    virtual TDataBuffer* GetTxFrame( 

        const TWhaTxQueueState& aTxQueueState,

        TBool& aMore );

    /**

     * From DEthernetFrameMemMngr

    virtual void FreeTxPacket( TDataBuffer*& aPacket );

    /** 

     * From DEthernetFrameMemMngr

     * Determines if Tx from protocol stack side client should be resumed

     *  

     * @param aUserDataTxEnabled ETrue if user data Tx is enabled

     *        EFalse otherwise

     * @return ETrue if Tx should be resumed

     *         EFalse otherwise

     */

    virtual TBool ResumeClientTx( TBool aUserDataTxEnabled ) const;

    /** 

     * From DEthernetFrameMemMngr

     * Determines if all protocol stack side client's Tx queues are empty

     * 

     * @return ETrue if all Tx queues are empty

     *         EFalse otherwise

     */

    virtual TBool AllTxQueuesEmpty() const;

    /** kernel address of frame xfer block */

    RFrameXferBlockProtocolStack* iFrameXferBlockProtoStack;

    * the offset from a User space address to the corresponding address

    * in the Kernel space in the shared memory chunk. May also be negative 

    TInt32 iUserToKernAddrOffset;