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// Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).
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// All rights reserved.
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// This component and the accompanying materials are made available
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// under the terms of "Eclipse Public License v1.0"
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// which accompanies this distribution, and is available
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// at the URL "http://www.eclipse.org/legal/epl-v10.html".
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//
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// Initial Contributors:
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// Nokia Corporation - initial contribution.
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//
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// Contributors:
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//
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// Description:
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// MMFAudioImaAdpcmToS16PcmCodec.cpp
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//
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//
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#include "MMFAudioImaAdpcmToS16PcmCodec.h"
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/**
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*
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* Convert
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* @param aSrc
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* @param aDst
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* @param aSamples
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*
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*/
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EXPORT_C void TMMFAudioImaAdpcmToS16PcmCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)
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{
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TInt delta; // Current adpcm output value
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TInt step; // Stepsize
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TInt valpred; // Predicted value
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TInt vpdiff; // Current change to valpred
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TInt index; // Current step change index
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//[Read first sample and index from block header
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// we do not need to store the information across calls
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//since we process the entire block here]
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valpred = (*aSrc++) & KAndMask8bit;
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valpred |= STATIC_CAST(TInt16, ((*aSrc++) << 8));
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index = *aSrc++;
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TUint8* dst=aDst;
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aSrc++; //skip reserved header byte
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//Write first sample to dest
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*aDst++ = STATIC_CAST( TUint8, valpred);
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*aDst++ = STATIC_CAST( TUint8, valpred >> 8);
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dst += 2;
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aSamples --;
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TBool theBufferStep = ETrue;
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TInt bufferValue = 0;
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for ( ; aSamples > 0 ; aSamples-- )
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{
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// Step 1 - get the delta value
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if ( theBufferStep)
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{
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bufferValue = *aSrc++;
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delta = bufferValue & 0xf;
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}
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else
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{
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delta = (bufferValue >> 4) & 0xf;
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}
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theBufferStep = !theBufferStep;
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ASSERT(index >= 0);
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step = KStepSizeTable[index];
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vpdiff = step>>3;
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if ( delta & 4 )
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vpdiff += step;
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if ( delta & 2 )
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vpdiff += step>>1;
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if ( delta & 1 )
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vpdiff += step>>2;
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if ( delta & 8 )
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valpred -= vpdiff;
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else
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valpred += vpdiff;
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if ( valpred > (KClamp - 1) )
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valpred = (KClamp - 1);
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else if ( valpred < -KClamp )
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valpred = -KClamp;
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index += KIndexTable[delta];
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if ( index < 0 )
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index = 0;
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if ( index > KMaxImaAdpcmTableEntries )
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index = KMaxImaAdpcmTableEntries;
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*dst++ = STATIC_CAST( TUint8, valpred&KAndMask8bit);
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*dst++ = STATIC_CAST( TUint8, (valpred>>8) );
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}
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}
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// IMA-ADPCM step variation table
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const TInt TMMFAudioImaAdpcmToS16PcmCodec::KIndexTable[] =
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{
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-1, -1, -1, -1, 2, 4, 6, 8,
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-1, -1, -1, -1, 2, 4, 6, 8
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};
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const TInt TMMFAudioImaAdpcmToS16PcmCodec::KStepSizeTable[89] =
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{
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7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
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19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
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50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
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130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
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337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
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876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
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2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
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5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
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15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
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};
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