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: //
sl@0: 
sl@0: #include "MMFAudioPcm16ToImaAdpcmCodec.h"
sl@0: 
sl@0: 
sl@0: EXPORT_C void TMMFAudioPcm16ToImaAdpcmCodec::SetState(const TMMFImaAdpcmCodecState& aState)
sl@0: 	{
sl@0:      iState = aState ;
sl@0: 	}
sl@0: 
sl@0: EXPORT_C const TMMFImaAdpcmCodecState& TMMFAudioPcm16ToImaAdpcmCodec::GetState()
sl@0: 	{
sl@0: 	return iState;
sl@0: 	}
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 TMMFAudioPcm16ToImaAdpcmCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)
sl@0: 	{
sl@0: 	TInt val;			// Current input sample value 
sl@0:     TInt sign;			// Current adpcm sign bit 
sl@0:     TInt delta;			// Current adpcm output value 
sl@0: 	TInt diff;			// Difference between val and valprev 
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: 	TInt16* srcPtr=REINTERPRET_CAST(TInt16*, aSrc);
sl@0: 	TInt16* src=srcPtr;
sl@0: 	
sl@0: 	iState.iPredicted = *aSrc++;
sl@0: 	iState.iPredicted |= STATIC_CAST(TInt16, ((*aSrc++) << 8));
sl@0: 	
sl@0:     valpred = iState.iPredicted;
sl@0:     index = iState.iIndex;
sl@0:     ASSERT(index >= 0);
sl@0:     step = KStepSizeTable[index];
sl@0: 	
sl@0: 	//Write block header
sl@0: 	*aDst++ = STATIC_CAST( TUint8, valpred);
sl@0: 	*aDst++ = STATIC_CAST( TUint8, valpred >> 8);
sl@0: 	*aDst++ = STATIC_CAST( TUint8, index);
sl@0: 	*aDst++ = 0; //reserved byte
sl@0: 	src++;
sl@0: 	aSamples --;	
sl@0: 	
sl@0: 	for (; aSamples > 0; aSamples--) 
sl@0: 		{ 
sl@0: 		val = *src;
sl@0: 		src++;
sl@0: 		
sl@0: 		step = KStepSizeTable[index];
sl@0: 		
sl@0: 		// Step 1 - compute difference with previous value 
sl@0: 		diff = val - valpred;
sl@0: 		sign = (diff < 0) ? 8 : 0;
sl@0: 		if ( sign ) diff = (-diff);
sl@0: 		
sl@0: 		// Step 2 - Divide and clamp 
sl@0: 		// Note:
sl@0: 		// This code *approximately* computes:
sl@0: 		//    delta = diff*4/step;
sl@0: 		//    vpdiff = (delta+0.5)*step/4;
sl@0: 		// but in shift step bits are dropped. The net result of this is
sl@0: 		// that even if you have fast mul/div hardware you cannot put it to
sl@0: 		// good use since the fixup would be too expensive.
sl@0: 		//
sl@0: 		delta = 0;
sl@0: 		vpdiff = (step >> 3);
sl@0: 		
sl@0: 		if ( diff >= step ) 
sl@0: 			{
sl@0: 			delta = 4;
sl@0: 			diff -= step;
sl@0: 			vpdiff += step;
sl@0: 			}
sl@0: 		step >>= 1;
sl@0: 		if ( diff >= step  ) 
sl@0: 			{
sl@0: 			delta |= 2;
sl@0: 			diff -= step;
sl@0: 			vpdiff += step;
sl@0: 			}
sl@0: 		step >>= 1;
sl@0: 		if ( diff >= step ) 
sl@0: 			{
sl@0: 			delta |= 1;
sl@0: 			vpdiff += step;
sl@0: 			}
sl@0: 		
sl@0: 		// Step 3 - Update previous value 
sl@0: 		if ( sign )
sl@0: 			valpred -= vpdiff;
sl@0: 		else
sl@0: 			valpred += vpdiff;
sl@0: 		
sl@0: 		// Step 4 - Clamp previous value to 16 bits 
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: 		// Step 5 - Assemble value, update index and step values 
sl@0: 		delta |= sign;
sl@0: 		
sl@0: 		index += KIndexTable[delta];
sl@0: 		if ( index < 0 ) index = 0;
sl@0: 		if ( index > 88 ) index = 88;
sl@0: 		
sl@0: 		// Step 6 - Output value 
sl@0: 		if (iBufferStep) 
sl@0: 			iBuffer = delta & 0x0f;
sl@0: 		else 
sl@0: 			*aDst++ = STATIC_CAST( TInt8, ((delta << 4) & 0xf0) | iBuffer);
sl@0: 		
sl@0: 		iBufferStep = !iBufferStep;
sl@0: 		}
sl@0: 	
sl@0: 	iState.iPredicted = STATIC_CAST(TInt16, valpred);
sl@0: 	iState.iIndex = STATIC_CAST(TUint8, index);
sl@0: 	}
sl@0: 
sl@0: // IMA-ADPCM step variation table 
sl@0: const TInt TMMFAudioPcm16ToImaAdpcmCodec::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 TMMFAudioPcm16ToImaAdpcmCodec::KStepSizeTable[] = 
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: 	};
sl@0: 	
sl@0: 
sl@0: 
sl@0: