1 // Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).

     2 // All rights reserved.

     3 // This component and the accompanying materials are made available

     4 // under the terms of "Eclipse Public License v1.0"

     5 // which accompanies this distribution, and is available

     6 // at the URL "http://www.eclipse.org/legal/epl-v10.html".

     7 //

     8 // Initial Contributors:

     9 // Nokia Corporation - initial contribution.

    10 //

    11 // Contributors:

    12 //

    13 // Description:

    14 //

    15 

    16 #include "MMFAudioSPcm16ToMuLawCodec.h"

    17 

    18 /***

    19 *

    20 * Convert

    21 *

    22 */

    23 EXPORT_C void TMMFAudioSPcm16ToMuLawCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)

    24 	{

    25 	TInt pcm;

    26 	while (aSamples--)

    27 		{

    28 		pcm = (aSrc[0]+(aSrc[1]<<8));

    29 		*aDst++ = PcmSampleToMuLaw(STATIC_CAST(TInt16 , pcm));

    30 		aSrc+=2;

    31 		}

    32 	}

    33 

    34 //[ conversion look up table pcm16 to Mulaw ]

    35 const TInt8 TMMFAudioSPcm16ToMuLawCodec::KExpLut[] = 

    36 	{

    37 	0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,

    38 	4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,

    39 	5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,

    40 	5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,

    41 	6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,

    42 	6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,

    43 	6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,

    44 	6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,

    45 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

    46 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

    47 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

    48 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

    49 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

    50 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

    51 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

    52 	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7

    53 	};

    54 

    55 /***

    56 *

    57 * PcmSampleToMulaw

    58 * @param Mulaw

    59 * @return TUint8

    60 *

    61 */

    62 TUint8 TMMFAudioSPcm16ToMuLawCodec::PcmSampleToMuLaw(TInt aPcm)

    63 	{

    64     TInt sign, exponent, mantissa;

    65     TUint8 ulawbyte;

    66 

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

    68     if ( sign != 0 )

    69 		aPcm = STATIC_CAST( TUint16,-aPcm);

    70 	if ( STATIC_CAST(TUint , aPcm) > STATIC_CAST(TUint , KMda16PcmToMulawClip ))

    71 		aPcm = KMda16PcmToMulawClip;	

    72 

    73     aPcm = STATIC_CAST(TInt16 , aPcm + KMda16PcmToMulawBias);

    74     exponent = KExpLut[( aPcm >> 7 ) & KAndMask8bit];

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

    76     ulawbyte = STATIC_CAST( TUint8, ~ ( sign | ( exponent << 4 ) | mantissa ));

    77 

    78     return ulawbyte;

    79 	}