sl@0: // Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: //
sl@0: 
sl@0: #include "MMFAudioSPcm16ToALawCodec.h"
sl@0: 
sl@0: /***
sl@0: *
sl@0: * Convert
sl@0: *
sl@0: */
sl@0: EXPORT_C void TMMFAudioSPcm16ToAlawCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)
sl@0: 	{
sl@0: 	TInt16* pcm = (TInt16*)aSrc;
sl@0: 	TInt16* pcmLimit = pcm + aSamples; 
sl@0: 
sl@0: 	while (pcm < pcmLimit)
sl@0: 		{
sl@0: 		*aDst++ = PcmSampleToAlaw(*pcm++);
sl@0: 		}
sl@0: 
sl@0: 	}
sl@0: 
sl@0: //[ conversion look up table pcm16 to alaw ]
sl@0: const TInt8 TMMFAudioSPcm16ToAlawCodec::KExpLut[] = 
sl@0: 	{
sl@0: 	1,1,2,2,3,3,3,3,
sl@0: 	4,4,4,4,4,4,4,4,
sl@0: 	5,5,5,5,5,5,5,5,
sl@0: 	5,5,5,5,5,5,5,5,
sl@0: 	6,6,6,6,6,6,6,6,
sl@0: 	6,6,6,6,6,6,6,6,
sl@0: 	6,6,6,6,6,6,6,6,
sl@0: 	6,6,6,6,6,6,6,6,
sl@0: 	7,7,7,7,7,7,7,7,
sl@0: 	7,7,7,7,7,7,7,7,
sl@0: 	7,7,7,7,7,7,7,7,
sl@0: 	7,7,7,7,7,7,7,7,
sl@0: 	7,7,7,7,7,7,7,7,
sl@0: 	7,7,7,7,7,7,7,7,
sl@0: 	7,7,7,7,7,7,7,7,
sl@0: 	7,7,7,7,7,7,7,7
sl@0: 	};
sl@0: 
sl@0: /***
sl@0: *
sl@0: * PcmSampleToAlaw
sl@0: * @param aLaw
sl@0: * @return TUint8
sl@0: *
sl@0: */
sl@0: TUint8 TMMFAudioSPcm16ToAlawCodec::PcmSampleToAlaw(TInt aPcm)
sl@0: 	{
sl@0:     TInt sign;
sl@0: 	TInt exponent;
sl@0: 	TInt mantissa;
sl@0: 	TUint8 alawbyte;
sl@0: 
sl@0:     sign = ((~aPcm) >> 8) & KMaskSign8bit;		
sl@0:     if (sign == 0)
sl@0: 		aPcm = -aPcm;	
sl@0:     if (aPcm > KMda16PcmToAlawClip) 
sl@0: 		aPcm = KMda16PcmToAlawClip;
sl@0: 
sl@0:     if (aPcm >= 256)
sl@0: 		{
sl@0: 		exponent = KExpLut[( aPcm >> 8 ) & 0x7F];
sl@0: 		mantissa = ( aPcm >> ( exponent + 3 ) ) & 0x0F;
sl@0: 		alawbyte = STATIC_CAST( TUint8, (( exponent << 4 ) | mantissa));
sl@0: 		}
sl@0:     else
sl@0: 		alawbyte = STATIC_CAST( TUint8, aPcm >> 4);
sl@0: 
sl@0:     alawbyte ^= (sign ^ 0x55);
sl@0: 
sl@0:     return alawbyte;
sl@0: 	}
sl@0: