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      1 /*
      2  * Copyright (C) 2004-2010 NXP Software
      3  * Copyright (C) 2010 The Android Open Source Project
      4  *
      5  * Licensed under the Apache License, Version 2.0 (the "License");
      6  * you may not use this file except in compliance with the License.
      7  * You may obtain a copy of the License at
      8  *
      9  *      http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  * Unless required by applicable law or agreed to in writing, software
     12  * distributed under the License is distributed on an "AS IS" BASIS,
     13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  * See the License for the specific language governing permissions and
     15  * limitations under the License.
     16  */
     17 
     18 #include "BIQUAD.h"
     19 #include "BP_1I_D16F16Css_TRC_WRA_01_Private.h"
     20 #include "LVM_Macros.h"
     21 
     22 
     23 /**************************************************************************
     24  ASSUMPTIONS:
     25  COEFS-
     26  pBiquadState->coefs[0] is A0,
     27  pBiquadState->coefs[1] is -B2,
     28  pBiquadState->coefs[2] is -B1, these are in Q14 format
     29 
     30  DELAYS-
     31  pBiquadState->pDelays[0] is x(n-1)L in Q0 format
     32  pBiquadState->pDelays[1] is x(n-2)L in Q0 format
     33  pBiquadState->pDelays[2] is y(n-1)L in Q0 format
     34  pBiquadState->pDelays[3] is y(n-2)L in Q0 format
     35 ***************************************************************************/
     36 
     37 void BP_1I_D16F16C14_TRC_WRA_01 ( Biquad_Instance_t       *pInstance,
     38                                   LVM_INT16               *pDataIn,
     39                                   LVM_INT16               *pDataOut,
     40                                   LVM_INT16               NrSamples)
     41 
     42 
     43     {
     44         LVM_INT32 ynL;
     45         LVM_INT16 ii;
     46         PFilter_State pBiquadState = (PFilter_State) pInstance;
     47 
     48          for (ii = NrSamples; ii != 0; ii--)
     49          {
     50 
     51 
     52             /**************************************************************************
     53                             PROCESSING OF THE LEFT CHANNEL
     54             ***************************************************************************/
     55             // ynL= (A0 (Q14) * (x(n)L (Q0) - x(n-2)L (Q0) ) )  in Q14
     56             ynL=(LVM_INT32)pBiquadState->coefs[0]* ((*pDataIn)-pBiquadState->pDelays[1]);
     57 
     58             // ynL+= ((-B2 (Q14) * y(n-2)L (Q0) ) ) in Q14
     59             ynL+=(LVM_INT32)pBiquadState->coefs[1]*pBiquadState->pDelays[3];
     60 
     61             // ynL+= ((-B1 (Q30) * y(n-1)L (Q0) ) ) in Q14
     62             ynL+=(LVM_INT32)pBiquadState->coefs[2]*pBiquadState->pDelays[2];
     63 
     64             ynL=(LVM_INT16)(ynL>>14); // ynL in Q0
     65             /**************************************************************************
     66                             UPDATING THE DELAYS
     67             ***************************************************************************/
     68             pBiquadState->pDelays[3]=pBiquadState->pDelays[2]; // y(n-2)L=y(n-1)L
     69             pBiquadState->pDelays[1]=pBiquadState->pDelays[0]; // x(n-2)L=x(n-1)L
     70             pBiquadState->pDelays[2]=ynL; // Update y(n-1)L in Q0
     71             pBiquadState->pDelays[0]=(*pDataIn++); // Update x(n-1)L in Q0
     72 
     73             /**************************************************************************
     74                             WRITING THE OUTPUT
     75             ***************************************************************************/
     76             *pDataOut++=(LVM_INT16)ynL; // Write Left output in Q0
     77 
     78         }
     79 
     80     }
     81 
     82