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: // MMFAudioImaAdpcmToS16PcmCodec.cpp
sl@0: // 
sl@0: //
sl@0: 
sl@0: #include "MMFAudioImaAdpcmToS16PcmCodec.h"
sl@0: 
sl@0: /**
sl@0: *
sl@0: * Convert
sl@0: * @param aSrc
sl@0: * @param aDst
sl@0: * @param aSamples
sl@0: *
sl@0: */
sl@0: EXPORT_C void TMMFAudioImaAdpcmToS16PcmCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)
sl@0: 	{
sl@0: 	TInt delta;			// Current adpcm output value 
sl@0:     TInt step;			// Stepsize
sl@0:     TInt valpred;		// Predicted value 
sl@0:     TInt vpdiff;		// Current change to valpred 
sl@0:     TInt index;			// Current step change index 
sl@0: 
sl@0: 	//[Read first sample and index from block header
sl@0: 	// we do not need to store the information across calls 
sl@0: 	//since we process the entire block here]
sl@0: 	valpred = (*aSrc++) & KAndMask8bit;
sl@0: 	valpred |= STATIC_CAST(TInt16, ((*aSrc++) << 8));
sl@0: 	index = *aSrc++;
sl@0: 	TUint8* dst=aDst;
sl@0: 
sl@0: 	aSrc++; //skip reserved header byte
sl@0: 
sl@0: 	//Write first sample to dest
sl@0: 	*aDst++ = STATIC_CAST( TUint8, valpred);
sl@0: 	*aDst++ = STATIC_CAST( TUint8, valpred >> 8);
sl@0: 	dst += 2;
sl@0: 	aSamples --;
sl@0: 
sl@0: 	TBool theBufferStep = ETrue;
sl@0:     TInt  bufferValue = 0;
sl@0: 	for ( ; aSamples > 0 ; aSamples-- ) 
sl@0: 		{ 
sl@0: 		// Step 1 - get the delta value
sl@0: 		if ( theBufferStep) 
sl@0: 			{
sl@0: 			bufferValue = *aSrc++;
sl@0: 			delta = bufferValue & 0xf;
sl@0: 			} 
sl@0: 		else 
sl@0: 			{
sl@0: 			delta = (bufferValue >> 4) & 0xf;
sl@0: 			}
sl@0: 
sl@0: 		theBufferStep = !theBufferStep;
sl@0: 
sl@0: 		ASSERT(index >= 0);
sl@0: 		step = KStepSizeTable[index];
sl@0: 
sl@0: 		vpdiff = step>>3;
sl@0: 		if ( delta & 4 ) 
sl@0: 			vpdiff += step;
sl@0: 		if ( delta & 2 ) 
sl@0: 			vpdiff += step>>1;
sl@0: 		if ( delta & 1 ) 
sl@0: 			vpdiff += step>>2;
sl@0: 
sl@0: 		if ( delta & 8 )
sl@0: 			valpred -= vpdiff;
sl@0: 		else
sl@0: 			valpred += vpdiff;
sl@0: 
sl@0: 		if ( valpred > (KClamp - 1) )
sl@0: 			valpred = (KClamp - 1);
sl@0: 		else if ( valpred < -KClamp )
sl@0: 			valpred = -KClamp;
sl@0: 
sl@0: 		index += KIndexTable[delta];
sl@0: 		if ( index < 0 ) 
sl@0: 			index = 0;
sl@0: 		if ( index > KMaxImaAdpcmTableEntries ) 
sl@0: 			index = KMaxImaAdpcmTableEntries;
sl@0: 
sl@0: 		*dst++ = STATIC_CAST( TUint8, valpred&KAndMask8bit);
sl@0: 		*dst++ = STATIC_CAST( TUint8, (valpred>>8) );
sl@0: 		}
sl@0: 	}
sl@0: 
sl@0: 
sl@0: 
sl@0: // IMA-ADPCM step variation table 
sl@0: const TInt TMMFAudioImaAdpcmToS16PcmCodec::KIndexTable[] =
sl@0:  	{
sl@0:     -1, -1, -1, -1, 2, 4, 6, 8,
sl@0:     -1, -1, -1, -1, 2, 4, 6, 8
sl@0: 	};
sl@0: 
sl@0: const TInt TMMFAudioImaAdpcmToS16PcmCodec::KStepSizeTable[89] = 
sl@0: 	{
sl@0:    7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
sl@0:    19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
sl@0:    50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
sl@0:    130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
sl@0:    337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
sl@0:    876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
sl@0:    2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
sl@0:    5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
sl@0:    15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
sl@0: 	};