// Copyright (c) 2003-2009 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:

 //

 #include "MMFAudioSPcm16ToALawCodec.h"

 /***

 *

 * Convert

 *

 */

 EXPORT_C void TMMFAudioSPcm16ToAlawCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)

 	{

 	TInt16* pcm = (TInt16*)aSrc;

 	TInt16* pcmLimit = pcm + aSamples; 

 	while (pcm < pcmLimit)

 		{

 		*aDst++ = PcmSampleToAlaw(*pcm++);

 		}

 	}

 //[ conversion look up table pcm16 to alaw ]

 const TInt8 TMMFAudioSPcm16ToAlawCodec::KExpLut[] = 

 	{

 	1,1,2,2,3,3,3,3,

 	4,4,4,4,4,4,4,4,

 	5,5,5,5,5,5,5,5,

 	5,5,5,5,5,5,5,5,

 	6,6,6,6,6,6,6,6,

 	6,6,6,6,6,6,6,6,

 	6,6,6,6,6,6,6,6,

 	6,6,6,6,6,6,6,6,

 	7,7,7,7,7,7,7,7,

 	7,7,7,7,7,7,7,7,

 	7,7,7,7,7,7,7,7,

 	7,7,7,7,7,7,7,7,

 	7,7,7,7,7,7,7,7,

 	7,7,7,7,7,7,7,7,

 	7,7,7,7,7,7,7,7,

 	7,7,7,7,7,7,7,7

 	};

 /***

 *

 * PcmSampleToAlaw

 * @param aLaw

 * @return TUint8

 *

 */

 TUint8 TMMFAudioSPcm16ToAlawCodec::PcmSampleToAlaw(TInt aPcm)

 	{

     TInt sign;

 	TInt exponent;

 	TInt mantissa;

 	TUint8 alawbyte;

     sign = ((~aPcm) >> 8) & KMaskSign8bit;		

     if (sign == 0)

 		aPcm = -aPcm;	

     if (aPcm > KMda16PcmToAlawClip) 

 		aPcm = KMda16PcmToAlawClip;

     if (aPcm >= 256)

 		{

 		exponent = KExpLut[( aPcm >> 8 ) & 0x7F];

 		mantissa = ( aPcm >> ( exponent + 3 ) ) & 0x0F;

 		alawbyte = STATIC_CAST( TUint8, (( exponent << 4 ) | mantissa));

 		}

     else

 		alawbyte = STATIC_CAST( TUint8, aPcm >> 4);

     alawbyte ^= (sign ^ 0x55);

     return alawbyte;

 	}