// Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "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:

#ifndef REQUEST_BUFFER_H_

#define REQUEST_BUFFER_H_

#include "serializerplatform.h"

/*

 * Base for ring buffer users

 */

class MRequestBufferBookKeepingBase

    {

public:

    virtual TUint32 GetWriteCount() = 0;

    virtual TUint32 GetReadCount() = 0;

    virtual TUint32 BufferTail() = 0;

    };

/*

 * Ring buffer writer. Data source for ring buffer.

 */

class MRequestBufferBookKeepingWriter: public MRequestBufferBookKeepingBase

    {

public:

    virtual TUint32 BufferHead() = 0;

    virtual void SetBufferHead( TUint32 aIndex ) = 0;

    virtual void IncrementWriteCount( TUint32 aWriteCount ) = 0;

    virtual void SetMaxTailIndex( TUint32 aIndex ) = 0;

    };

/*

 * Ring buffer reader. Data consumer for ring buffer.

 */

class MRequestBufferBookKeepingReader: public MRequestBufferBookKeepingBase

    {

public:

    virtual void SetBufferTail( TUint32 aIndex ) = 0;

    virtual void IncrementReadCount( TUint32 aReadCount ) = 0;

    virtual TUint32 MaxTailIndex() = 0;

    };

class RequestBufferBase

    {

public:

    /*

     * 

     */

    static TUint32 AdjustAlignment( TUint32 aIndex, const TUint32 aAlignment )

    {

    const TUint32 remainder = aIndex % aAlignment;

    if ( remainder )

        {

        aIndex += aAlignment - remainder;

        }

    return aIndex;

    }

protected:

    /*

     * 

     */

    RequestBufferBase( TUint32 aSize ):

        iSize( aSize )

        {}

protected:

    const TUint32 iSize;

    };

class RequestBufferWriter: RequestBufferBase

    {

public:

    /*

     * 

     */

    RequestBufferWriter( MRequestBufferBookKeepingWriter& aBookKeeper, TUint32 aSize ): 

        RequestBufferBase( aSize ),

        iBookKeeper( aBookKeeper )

        {}

    /*

     * 

     */

    void InitBuffer()

        {

        iBookKeeper.SetBufferHead( 0 );    

        iBookKeeper.SetMaxTailIndex( iSize );

        }

    /*

     * Does not check for free space, assure free space by using CheckForSpace

     */

    TUint32 AllocateBytes( const TUint32 aBytes )

        {

        TUint32 base = iBookKeeper.BufferHead();

        if ( base + aBytes > iSize )

            {

            iBookKeeper.SetMaxTailIndex( base );

            base = 0;

            }

        else if ( iBookKeeper.BufferTail() <= base )

            {

            iBookKeeper.SetMaxTailIndex( iSize );

            }

        return base;

        }

    /*

     * Does not check for free space, assure free space by using CheckForSpace

     */

    void CommitBytes( const TUint32 aBase, const TUint32 aBytes )

        {

        //TUint32 base = CheckIndexForWrapAround( AdjustAlignment( aBase + aBytes, 4 ) );

        TUint32 base = AdjustAlignment( aBase + aBytes, 4 );

		const TUint32 inc( base - aBase );

        iBookKeeper.SetBufferHead( base );

        iBookKeeper.IncrementWriteCount( inc );

        }

    /*

     * 

     */

    TBool CheckForSpace( const TUint32 aSpaceNeeded )

        {

        const TUint32 inputBufferHead( iBookKeeper.BufferHead() );

        const TUint32 inputBufferTail( iBookKeeper.BufferTail() );

        //Notice that tail might grow during the execution of this function

        // but it would only cause false negative as a result

        //Buffer can be empty or full

        if ( inputBufferHead == inputBufferTail )

            {

            //Check if the buffer is full or empty

            if ( iBookKeeper.GetWriteCount() - iBookKeeper.GetReadCount() )

                {

                //Buffer is full

                return EFalse;

                }

            }

        //Let's check if the SFC fits to the buffer

        const TUint32 newHeadIndex = inputBufferHead + aSpaceNeeded;// + alignmentAdjust;

        if ( inputBufferHead < inputBufferTail && newHeadIndex > inputBufferTail )

            {

            //Buffer does not have enough space

            return EFalse; 

            }

        else if ( inputBufferHead >= inputBufferTail )

            {

            if ( newHeadIndex > iSize && aSpaceNeeded > inputBufferTail )

                {

                //Buffer does not have enough space

                return EFalse;

                }

            }

        return ETrue;        

        }

private:

    MRequestBufferBookKeepingWriter& iBookKeeper;

    };

class RequestBufferReader: public RequestBufferBase

    {

public:

    /*

     * 

     */

    RequestBufferReader( MRequestBufferBookKeepingReader& aBookKeeper, TUint32 aSize ): 

        RequestBufferBase( aSize ),

        iBookKeeper( aBookKeeper )

        {}

    /*

     * 

     */

    void InitBuffer()

        {

        iBookKeeper.SetBufferTail( 0 );

        }

    /*

     * 

     */

    TUint32 GetReadIndex()

        {

		const TUint32 bufTail( iBookKeeper.BufferTail() );

		const TUint32 bufTail2( CheckIndexForWrapAround( bufTail ) );

        if ( bufTail != bufTail2 )

			{

			iBookKeeper.SetBufferTail( bufTail2 );

			}

		return bufTail2;

        }

    /*

     * 

     */

    void FreeBytes( TUint32 aBytes )

        {

		const TUint32 oldTail(iBookKeeper.BufferTail());

        TUint32 newBufferTail = AdjustAlignment( aBytes + oldTail, 4 );

		const TUint32 inc( newBufferTail - oldTail );

        newBufferTail = CheckIndexForWrapAround( newBufferTail );

        iBookKeeper.IncrementReadCount( inc );

        iBookKeeper.SetBufferTail( newBufferTail );

        }

    /*

     * 

     */

    TBool IsDataAvailable()

        {

		const TUint32 readc( iBookKeeper.GetReadCount() );

		const TUint32 writec( iBookKeeper.GetWriteCount() );

        return readc != writec;

        }   

    /*

     * 

     */

    TUint32 CheckIndexForWrapAround( TUint32 aIndex )

        {

        //Head is behind of tail when MaxTailIndex is applied so

        // this routine works for head, too

        if ( aIndex >= iBookKeeper.MaxTailIndex() )

            {

            return 0;

            }

        return aIndex;

        }

private:

    MRequestBufferBookKeepingReader& iBookKeeper;

    };

#endif