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/*
* Copyright (C) 2004-2010 NXP Software
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "BIQUAD.h"
#include "FO_2I_D16F32Css_LShx_TRC_WRA_01_Private.h"
#include "LVM_Macros.h"
/**************************************************************************
ASSUMPTIONS:
COEFS-
pBiquadState->coefs[0] is A1,
pBiquadState->coefs[1] is A0,
pBiquadState->coefs[2] is -B1, these are in Q15 format
pBiquadState->Shift is Shift value
DELAYS-
pBiquadState->pDelays[0] is x(n-1)L in Q15 format
pBiquadState->pDelays[1] is y(n-1)L in Q30 format
pBiquadState->pDelays[2] is x(n-1)R in Q15 format
pBiquadState->pDelays[3] is y(n-1)R in Q30 format
***************************************************************************/
void FO_2I_D16F32C15_LShx_TRC_WRA_01(Biquad_Instance_t *pInstance,
LVM_INT16 *pDataIn,
LVM_INT16 *pDataOut,
LVM_INT16 NrSamples)
{
LVM_INT32 ynL,ynR;
LVM_INT32 Temp;
LVM_INT32 NegSatValue;
LVM_INT16 ii;
LVM_INT16 Shift;
PFilter_State pBiquadState = (PFilter_State) pInstance;
NegSatValue = LVM_MAXINT_16 +1;
NegSatValue = -NegSatValue;
Shift = pBiquadState->Shift;
for (ii = NrSamples; ii != 0; ii--)
{
/**************************************************************************
PROCESSING OF THE LEFT CHANNEL
***************************************************************************/
// ynL =A1 (Q15) * x(n-1)L (Q15) in Q30
ynL=(LVM_INT32)pBiquadState->coefs[0]* pBiquadState->pDelays[0];
// ynR =A1 (Q15) * x(n-1)R (Q15) in Q30
ynR=(LVM_INT32)pBiquadState->coefs[0]* pBiquadState->pDelays[2];
// ynL+=A0 (Q15) * x(n)L (Q15) in Q30
ynL+=(LVM_INT32)pBiquadState->coefs[1]* (*pDataIn);
// ynR+=A0 (Q15) * x(n)L (Q15) in Q30
ynR+=(LVM_INT32)pBiquadState->coefs[1]* (*(pDataIn+1));
// ynL += (-B1 (Q15) * y(n-1)L (Q30) ) in Q30
MUL32x16INTO32(pBiquadState->pDelays[1],pBiquadState->coefs[2],Temp,15);
ynL +=Temp;
// ynR += (-B1 (Q15) * y(n-1)R (Q30) ) in Q30
MUL32x16INTO32(pBiquadState->pDelays[3],pBiquadState->coefs[2],Temp,15);
ynR +=Temp;
/**************************************************************************
UPDATING THE DELAYS
***************************************************************************/
pBiquadState->pDelays[1]=ynL; // Update y(n-1)L in Q30
pBiquadState->pDelays[0]=(*pDataIn++); // Update x(n-1)L in Q15
pBiquadState->pDelays[3]=ynR; // Update y(n-1)R in Q30
pBiquadState->pDelays[2]=(*pDataIn++); // Update x(n-1)R in Q15
/**************************************************************************
WRITING THE OUTPUT
***************************************************************************/
/*Apply shift: Instead of left shift on 16-bit result, right shift of (15-shift) is applied
for better SNR*/
ynL = ynL>>(15-Shift);
ynR = ynR>>(15-Shift);
/*Saturate results*/
if(ynL > LVM_MAXINT_16)
{
ynL = LVM_MAXINT_16;
}
else
{
if(ynL < NegSatValue)
{
ynL = NegSatValue;
}
}
if(ynR > LVM_MAXINT_16)
{
ynR = LVM_MAXINT_16;
}
else
{
if(ynR < NegSatValue)
{
ynR = NegSatValue;
}
}
*pDataOut++=(LVM_INT16)ynL;
*pDataOut++=(LVM_INT16)ynR;
}
}
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