// 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

 	};