// 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;

	}