diff -r 013716db5021 -r d8d95053303a guestrendering/vghwserialiser/inc/requestbuffer.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/guestrendering/vghwserialiser/inc/requestbuffer.h	Fri Aug 20 18:02:40 2010 +0100
@@ -0,0 +1,255 @@
+// 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