examples/Multimedia/MmfExCodec/MMFExPcm8ToPcm16Codec.cpp

// MMFExPcm8Pcm16Codec.cpp
// Copyright (c) 1997-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// License: "Symbian Foundation License v1.0" to Symbian Foundation
// members and "Symbian Foundation End User License Agreement v1.0"
// to non-members at the URL
// "http://www.symbianfoundation.org/legal/licencesv10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
//

#include "MMFExPcm8ToPcm16Codec.h"


// Factory function
CMMFCodec* CMMFExPcm8Pcm16Codec::NewL(TAny* )
        {
        CMMFExPcm8Pcm16Codec* self=new(ELeave) CMMFExPcm8Pcm16Codec();
        return self;
        }

// Process source buffer and writes converted data to destination buffer
// The codec expands 1 byte to 2 bytes
TCodecProcessResult CMMFExPcm8Pcm16Codec::ProcessL(const CMMFBuffer& aSrc, CMMFBuffer& aDst)
        {
        TCodecProcessResult result;
        result.iStatus = TCodecProcessResult::EProcessIncomplete;

        // cast from generic CMMFBuffer to CMMFDataBuffer
        iSrc = STATIC_CAST(const CMMFDataBuffer*, &aSrc);
        iDst = STATIC_CAST(CMMFDataBuffer*, &aDst);

        const TUint dstMaxLen = iDst->Data().MaxLength();
        if (!dstMaxLen)
                User::Leave(KErrArgument);

        //don't scribble Destination (pDst) by only consuming enough source to fill pDst
        TUint srcUse = (dstMaxLen - iDst->Position()) / 2;
        const TUint srcLen = iSrc->Data().Length();
        const TUint sourceRemain = srcLen - iSrc->Position();

        //make sure we don't blow source by checking against remaining
        //and clipping to minimum remaining if necessary
        srcUse = (srcUse<sourceRemain ? srcUse : sourceRemain);
        
        //we need to cast away CONST even on the source, as the TClass needs a TUint8*
        TUint8* pSrc = CONST_CAST(TUint8*,iSrc->Data().Ptr());
        pSrc += iSrc->Position();
        TUint8* pDst = CONST_CAST(TUint8*,iDst->Data().Ptr());
        pDst += iDst->Position();

        Convert(pSrc, pDst, srcUse );

        if ((srcUse * 2) + iDst->Position() < dstMaxLen)
                result.iStatus = TCodecProcessResult::EDstNotFilled;

        else if (srcUse + iSrc->Position() >= srcLen)
                result.iStatus = TCodecProcessResult::EProcessComplete;

        result.iSrcBytesProcessed = srcUse;
        result.iDstBytesAdded = srcUse * 2;

        iDst->Data().SetLength(iDst->Position() + (srcUse * 2));

        return result;
        }


// Helper to convert signed 8-bit to signed 16-bit
void CMMFExPcm8Pcm16Codec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)
        {
        const TInt KAndMask8bit = 0xff;
        TInt s16;
        while (aSamples--)
                { 
                s16 = (*aSrc++)<<8;
                *aDst++ = STATIC_CAST( TInt8, s16&KAndMask8bit);
                *aDst++ = STATIC_CAST( TInt8, (s16>>8)&KAndMask8bit);
                }
        }

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