/*+
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* This component and the accompanying materials are made available+
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* under the terms of the License "Eclipse Public License v1.0"+
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* which accompanies this distribution, and is available+
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* at the URL "http://www.eclipse.org/legal/epl-v10.html".+
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*+
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* Initial Contributors:+
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* Accenture Ltd+
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*+
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* Contributors:+
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*+
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* Description: This file is a part of sound driver for Syborg adaptation.+
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*+
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*/+
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+
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#ifndef VIRTIO_QUEUE_H+
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#define VIRTIO_QUEUE_H+
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+
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#include "virtio.h"+
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#include <e32def.h>+
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+
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namespace VirtIo+
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{+
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+
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/// @brief implements VirtIo Queue.+
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/// +
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///+
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/// @note functions are not enclosed with any synchronisation primitives.+
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/// However, implementation is believed to split operations in 3 groups with the following concurrency constraints:+
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/// <li> A GetBuf, DetachBuf+
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/// <li> B AddBuf+
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/// <li> C Processing, Completed, Sync+
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/// Group C can be executed concurrently with any other functions.+
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/// Group A can be executed concurrently with a group B function.+
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/// Group A or B function cannot be executed concurrently with function from the same group.+
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///+
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/// Memory barries would have to be introduced for SMP.+
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///+
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class DQueue : public DBase, public MQueue+
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	{+
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	typedef TUint16 TIdx;+
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+
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	struct TTransactionInfo+
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		{+
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		Token iToken;+
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		TUint iTotalLen;+
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		};+
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	+
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	static const TUint KFreeDescriptorMarker = 0xFFFF;+
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	+
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public:+
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+
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	/// @brief Creates a VirtIo Queue with a MIo object, Queue Id,+
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	/// and descriptor count/ring lenght.+
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	DQueue( MIo& aVirtIo, TUint aId, TUint aCount );+
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	+
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	/// Allocates resources+
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	TInt Construct();+
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		+
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	virtual ~DQueue();+
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	+
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public: // implementation of MQueue+
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	+
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	virtual TInt AddBuf( const TAddrLen aScatterList[], TUint32 aOutNum, TUint32 aInNum, Token aToken);+
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	+
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	virtual TInt DetachBuf( Token aToken );+
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	+
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	virtual Token GetBuf( TUint& aLen );+
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	+
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	virtual void Sync();+
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	+
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	virtual TUint Id() +
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		{ return iId; }+
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	+
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	virtual TBool Restart()+
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		{ return ETrue;	}+
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	+
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	virtual TInt Processing();+
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			+
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	virtual TInt Completed();	+
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	+
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public:	// Debug functions +
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	void DumpUsedPending();+
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	+
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	void DumpUsed(TUint usedSlot);+
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	void DumpAvailPending();+
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	+
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	void DumpAvail(TUint availSlot);+
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	void DumpDescs(TUint descId );+
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	+
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	virtual void DumpAll();+
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		+
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private:+
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	void Wipe();+
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+
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	TUint Slot( TUint i )+
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		{ return i & (iCount - 1); }+
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				+
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	void FreeDescs( TUint firstDescIdx );+
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	+
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	TUint8* AllocMem( TUint aSize );+
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	+
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	TInt AllocQueue();+
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	+
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	void PreInitQueue();+
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	+
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	void PostInitQueue();+
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	+
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private:+
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	MIo& iVirtIo;+
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	const TUint iId;+
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	const TUint iCount;+
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	volatile TUint iNextUsedToRead;+
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	TUint iFirstEverToRead;+
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	volatile TUint iNextAvailToSync;+
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	TUint iFirstEverToSync;+
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+
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	TUint iDescSize;+
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	TUint iAvailSize;+
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	TUint iTokenSize;+
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	TUint iUsedSize;+
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	+
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	TRingDesc* iDesc;+
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	TRingAvail* iAvail;+
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	volatile TRingUsed* iUsed;+
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	TTransactionInfo* iToken;+
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	+
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	// managed+
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	TUint8* iMem;+
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	TPhysAddr iPhysAddr;+
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	TBool iPhysMemReallyAllocated;+
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	DPlatChunkHw* iChunk;+
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	+
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	};+
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+
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+
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} // namespace VirtIo+
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+
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#endif+
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