// 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 "MMFAudioPcm16ToImaAdpcmCodec.h"

EXPORT_C void TMMFAudioPcm16ToImaAdpcmCodec::SetState(const TMMFImaAdpcmCodecState& aState)

	{

     iState = aState ;

	}

EXPORT_C const TMMFImaAdpcmCodecState& TMMFAudioPcm16ToImaAdpcmCodec::GetState()

	{

	return iState;

	}

/**

*

* Convert

* @param aSrc

* @param aDst

* @param aSamples

*

*/

EXPORT_C void TMMFAudioPcm16ToImaAdpcmCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)

	{

	TInt val;			// Current input sample value 

    TInt sign;			// Current adpcm sign bit 

    TInt delta;			// Current adpcm output value 

	TInt diff;			// Difference between val and valprev 

	TInt step;			// Stepsize

    TInt valpred;		// Predicted value 

    TInt vpdiff;		// Current change to valpred 

    TInt index;			// Current step change index 

	TInt16* srcPtr=REINTERPRET_CAST(TInt16*, aSrc);

	TInt16* src=srcPtr;

	iState.iPredicted = *aSrc++;

	iState.iPredicted |= STATIC_CAST(TInt16, ((*aSrc++) << 8));

    valpred = iState.iPredicted;

    index = iState.iIndex;

    ASSERT(index >= 0);

    step = KStepSizeTable[index];

	//Write block header

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

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

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

	*aDst++ = 0; //reserved byte

	src++;

	aSamples --;	

	for (; aSamples > 0; aSamples--) 

		{ 

		val = *src;

		src++;

		step = KStepSizeTable[index];

		// Step 1 - compute difference with previous value 

		diff = val - valpred;

		sign = (diff < 0) ? 8 : 0;

		if ( sign ) diff = (-diff);

		// Step 2 - Divide and clamp 

		// Note:

		// This code *approximately* computes:

		//    delta = diff*4/step;

		//    vpdiff = (delta+0.5)*step/4;

		// but in shift step bits are dropped. The net result of this is

		// that even if you have fast mul/div hardware you cannot put it to

		// good use since the fixup would be too expensive.

		//

		delta = 0;

		vpdiff = (step >> 3);

		if ( diff >= step ) 

			{

			delta = 4;

			diff -= step;

			vpdiff += step;

			}

		step >>= 1;

		if ( diff >= step  ) 

			{

			delta |= 2;

			diff -= step;

			vpdiff += step;

			}

		step >>= 1;

		if ( diff >= step ) 

			{

			delta |= 1;

			vpdiff += step;

			}

		// Step 3 - Update previous value 

		if ( sign )

			valpred -= vpdiff;

		else

			valpred += vpdiff;

		// Step 4 - Clamp previous value to 16 bits 

		if ( valpred > KClamp - 1 )

			valpred = KClamp - 1;

		else if ( valpred < - KClamp )

			valpred = - KClamp;

		// Step 5 - Assemble value, update index and step values 

		delta |= sign;

		index += KIndexTable[delta];

		if ( index < 0 ) index = 0;

		if ( index > 88 ) index = 88;

		// Step 6 - Output value 

		if (iBufferStep) 

			iBuffer = delta & 0x0f;

		else 

			*aDst++ = STATIC_CAST( TInt8, ((delta << 4) & 0xf0) | iBuffer);

		iBufferStep = !iBufferStep;

		}

	iState.iPredicted = STATIC_CAST(TInt16, valpred);

	iState.iIndex = STATIC_CAST(TUint8, index);

	}

// IMA-ADPCM step variation table 

const TInt TMMFAudioPcm16ToImaAdpcmCodec::KIndexTable[] =

	{

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

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

	};

const TInt TMMFAudioPcm16ToImaAdpcmCodec::KStepSizeTable[] = 

	{

	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

	};