/*

* Copyright (c) 2010 Ixonos Plc.

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the "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:

* Ixonos Plc

*

* Description: 

* Data buffering and queuing support definitions, class CActiveQueue.

*

*/

#ifndef     __ACTIVEQUEUE_H__

#define     __ACTIVEQUEUE_H__

//  INCLUDES

#ifndef __E32BASE_H__

#include <e32base.h>

#endif

//  FORWARD DECLARATIONS

class CDataProcessor;

class CActiveQueue;

//#define BLOCK_GUARD_AREA

//  CLASS DEFINITIONS

// Queue block class

class TActiveQueueBlock : public TPtr8

{

    TActiveQueueBlock(TUint8 *aBuf, TInt aMaxLength) : TPtr8(aBuf, aMaxLength) {};

protected:

    friend class CActiveQueue;

    TActiveQueueBlock *iNextBlock; // next block in the allocated block list

    TActiveQueueBlock *iPrevBlock; // prev. block in the allocated block list

    TActiveQueueBlock *iNextList; // next block in the data queue / free list

};

// The queue class

class CActiveQueue : public CBase

{

public: // constants

    enum TErrorCode

    {

        EInternalAssertionFailure = -1000,

        ENoWriter = -1001, 

        ENoReader = -1002,

        EWriteAfterStreamEnd = -1003

    };

public: // interface functions

    // Constructors and destructor

    CActiveQueue(TUint aNumberOfBlocks, TUint aBlockLength);

    ~CActiveQueue();

    void ConstructL();

    // Set/remove reader

    void SetReader(CDataProcessor *aReader, TAny *aUserPointer);

    void RemoveReader();

    // Set/remove writer

    void SetWriter(CDataProcessor *aWriter, TAny *aUserPointer);

    void RemoveWriter();

    void ResetStreamEnd();

    // Get the number of free blocks available for new data

    TUint NumFreeBlocks();

    // Get the number of blocks with data queued

    TUint NumDataBlocks();

    // Get a free block for writing data into the queue (writer)

    TPtr8 *GetFreeBlockL(TUint aBlockLength);

    // Add a data block to the queue (writer)

    void WriteBlock(TPtr8 *aBlock);

    // Read a data block from the queue (reader)

    TPtr8 *ReadBlock();

    // Return a read block back to the empty block list (reader)

    void ReturnBlock(TPtr8 *aBlock);

    // Notify that the stream has ended (writer)

    void WriteStreamEnd();

    // Check if the writer has notified that the stream has ended (reader)

    TBool StreamEnded();

    // Testing aid: get total number of blocks

    TUint NumBlocks() { return iNumBlocks; };

private: // Internal methods

    TActiveQueueBlock *AllocateBlockL();

    void FreeBlockL(TActiveQueueBlock *aBlock);

private: // Data

    TUint iNewBlockLength; // length of new blocks that are allocated

    TUint iInitialBlocks; // initial number of blocks to allocate

    CDataProcessor *iReader; // the reader

    TAny *iReaderUserPointer;

    CDataProcessor *iWriter; // the writer

    TAny *iWriterUserPointer;

    TActiveQueueBlock *iBlocks; // the list of all allocated blocks

    TUint iNumBlocks; // total number of blocks

    TActiveQueueBlock *iFreeList; // the free block list

    TUint iNumFreeBlocks; // number of free blocks

    TActiveQueueBlock *iDataQueueHead; // the data queue head (where blocks are

                                       // read from)

    TActiveQueueBlock *iDataQueueTail; // the data queue tail (where blocks are

                                       // written to

    TUint iNumDataBlocks; // number of data blocks

    TBool iStreamEnd; // has the stream ended?

};

#endif      //  __ACTIVEQUEUE_H__

// End of File