/*

* 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:

* Accenture Ltd

*

* Contributors:

*

* Description: This file is a part of sound driver for Syborg adaptation.

*

*/

#ifndef VIRTIO_QUEUE_H

#define VIRTIO_QUEUE_H

#include "virtio.h"

#include <e32def.h>

namespace VirtIo

{

/// @brief implements VirtIo Queue.

/// 

///

/// @note functions are not enclosed with any synchronisation primitives.

/// However, implementation is believed to split operations in 3 groups with the following concurrency constraints:

/// <li> A GetBuf, DetachBuf

/// <li> B AddBuf

/// <li> C Processing, Completed, Sync

/// Group C can be executed concurrently with any other functions.

/// Group A can be executed concurrently with a group B function.

/// Group A or B function cannot be executed concurrently with function from the same group.

///

/// Memory barries would have to be introduced for SMP.

///

class DQueue : public DBase, public MQueue

	{

	typedef TUint16 TIdx;

	struct TTransactionInfo

		{

		Token iToken;

		TUint iTotalLen;

		};

	static const TUint KFreeDescriptorMarker = 0xFFFF;

public:

	/// @brief Creates a VirtIo Queue with a MIo object, Queue Id,

	/// and descriptor count/ring lenght.

	DQueue( MIo& aVirtIo, TUint aId, TUint aCount );

	/// Allocates resources

	TInt Construct();

	virtual ~DQueue();

public: // implementation of MQueue

	virtual TInt AddBuf( const TAddrLen aScatterList[], TUint32 aOutNum, TUint32 aInNum, Token aToken);

	virtual TInt DetachBuf( Token aToken );

	virtual Token GetBuf( TUint& aLen );

	virtual void Sync();

	virtual TUint Id() 

		{ return iId; }

	virtual TBool Restart()

		{ return ETrue;	}

	virtual TInt Processing();

	virtual TInt Completed();	

public:	// Debug functions 

	void DumpUsedPending();

	void DumpUsed(TUint usedSlot);

	void DumpAvailPending();

	void DumpAvail(TUint availSlot);

	void DumpDescs(TUint descId );

	virtual void DumpAll();

private:

	void Wipe();

	TUint Slot( TUint i )

		{ return i & (iCount - 1); }

	void FreeDescs( TUint firstDescIdx );

	TUint8* AllocMem( TUint aSize );

	TInt AllocQueue();

	void PreInitQueue();

	void PostInitQueue();

private:

	MIo& iVirtIo;

	const TUint iId;

	const TUint iCount;

	volatile TUint iNextUsedToRead;

	TUint iFirstEverToRead;

	volatile TUint iNextAvailToSync;

	TUint iFirstEverToSync;

	TUint iDescSize;

	TUint iAvailSize;

	TUint iTokenSize;

	TUint iUsedSize;

	TRingDesc* iDesc;

	TRingAvail* iAvail;

	volatile TRingUsed* iUsed;

	TTransactionInfo* iToken;

	// managed

	TUint8* iMem;

	TPhysAddr iPhysAddr;

	TBool iPhysMemReallyAllocated;

	DPlatChunkHw* iChunk;

	};

} // namespace VirtIo

#endif