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// Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).
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// All rights reserved.
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// This component and the accompanying materials are made available
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// under the terms of "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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// Nokia Corporation - initial contribution.
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//
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// Contributors:
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//
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// Description:
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//
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#include "MMFAudioSPcm16ToALawCodec.h"
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/***
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*
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* Convert
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*
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*/
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EXPORT_C void TMMFAudioSPcm16ToAlawCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)
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{
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TInt16* pcm = (TInt16*)aSrc;
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TInt16* pcmLimit = pcm + aSamples;
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while (pcm < pcmLimit)
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{
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*aDst++ = PcmSampleToAlaw(*pcm++);
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}
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}
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//[ conversion look up table pcm16 to alaw ]
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const TInt8 TMMFAudioSPcm16ToAlawCodec::KExpLut[] =
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{
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1,1,2,2,3,3,3,3,
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4,4,4,4,4,4,4,4,
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5,5,5,5,5,5,5,5,
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5,5,5,5,5,5,5,5,
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6,6,6,6,6,6,6,6,
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6,6,6,6,6,6,6,6,
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6,6,6,6,6,6,6,6,
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6,6,6,6,6,6,6,6,
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7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7
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};
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/***
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*
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* PcmSampleToAlaw
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* @param aLaw
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* @return TUint8
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*
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*/
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TUint8 TMMFAudioSPcm16ToAlawCodec::PcmSampleToAlaw(TInt aPcm)
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{
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TInt sign;
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TInt exponent;
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TInt mantissa;
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TUint8 alawbyte;
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sign = ((~aPcm) >> 8) & KMaskSign8bit;
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if (sign == 0)
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aPcm = -aPcm;
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if (aPcm > KMda16PcmToAlawClip)
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aPcm = KMda16PcmToAlawClip;
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if (aPcm >= 256)
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{
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exponent = KExpLut[( aPcm >> 8 ) & 0x7F];
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mantissa = ( aPcm >> ( exponent + 3 ) ) & 0x0F;
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alawbyte = STATIC_CAST( TUint8, (( exponent << 4 ) | mantissa));
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}
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else
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alawbyte = STATIC_CAST( TUint8, aPcm >> 4);
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alawbyte ^= (sign ^ 0x55);
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return alawbyte;
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}
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