// 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:

// MMFAudioImaAdpcmToS16PcmCodec.cpp

// 

//

#include "MMFAudioImaAdpcmToS16PcmCodec.h"

/**

*

* Convert

* @param aSrc

* @param aDst

* @param aSamples

*

*/

EXPORT_C void TMMFAudioImaAdpcmToS16PcmCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)

	{

	TInt delta;			// Current adpcm output value 

    TInt step;			// Stepsize

    TInt valpred;		// Predicted value 

    TInt vpdiff;		// Current change to valpred 

    TInt index;			// Current step change index 

	//[Read first sample and index from block header

	// we do not need to store the information across calls 

	//since we process the entire block here]

	valpred = (*aSrc++) & KAndMask8bit;

	valpred |= STATIC_CAST(TInt16, ((*aSrc++) << 8));

	index = *aSrc++;

	TUint8* dst=aDst;

	aSrc++; //skip reserved header byte

	//Write first sample to dest

	*aDst++ = STATIC_CAST( TUint8, valpred);

	*aDst++ = STATIC_CAST( TUint8, valpred >> 8);

	dst += 2;

	aSamples --;

	TBool theBufferStep = ETrue;

    TInt  bufferValue = 0;

	for ( ; aSamples > 0 ; aSamples-- ) 

		{ 

		// Step 1 - get the delta value

		if ( theBufferStep) 

			{

			bufferValue = *aSrc++;

			delta = bufferValue & 0xf;

			} 

		else 

			{

			delta = (bufferValue >> 4) & 0xf;

			}

		theBufferStep = !theBufferStep;

		ASSERT(index >= 0);

		step = KStepSizeTable[index];

		vpdiff = step>>3;

		if ( delta & 4 ) 

			vpdiff += step;

		if ( delta & 2 ) 

			vpdiff += step>>1;

		if ( delta & 1 ) 

			vpdiff += step>>2;

		if ( delta & 8 )

			valpred -= vpdiff;

		else

			valpred += vpdiff;

		if ( valpred > (KClamp - 1) )

			valpred = (KClamp - 1);

		else if ( valpred < -KClamp )

			valpred = -KClamp;

		index += KIndexTable[delta];

		if ( index < 0 ) 

			index = 0;

		if ( index > KMaxImaAdpcmTableEntries ) 

			index = KMaxImaAdpcmTableEntries;

		*dst++ = STATIC_CAST( TUint8, valpred&KAndMask8bit);

		*dst++ = STATIC_CAST( TUint8, (valpred>>8) );

		}

	}

// IMA-ADPCM step variation table 

const TInt TMMFAudioImaAdpcmToS16PcmCodec::KIndexTable[] =

 	{

    -1, -1, -1, -1, 2, 4, 6, 8,

    -1, -1, -1, -1, 2, 4, 6, 8

	};

const TInt TMMFAudioImaAdpcmToS16PcmCodec::KStepSizeTable[89] = 

	{

   7, 8, 9, 10, 11, 12, 13, 14, 16, 17,

   19, 21, 23, 25, 28, 31, 34, 37, 41, 45,

   50, 55, 60, 66, 73, 80, 88, 97, 107, 118,

   130, 143, 157, 173, 190, 209, 230, 253, 279, 307,

   337, 371, 408, 449, 494, 544, 598, 658, 724, 796,

   876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,

   2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,

   5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,

   15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767

	};