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 "BQ_1I_D16F16Css_TRC_WRA_01_Private.h" 20 #include "LVM_Macros.h" 21 22 /************************************************************************** 23 ASSUMPTIONS: 24 COEFS- 25 pBiquadState->coefs[0] is A2, pBiquadState->coefs[1] is A1 26 pBiquadState->coefs[2] is A0, pBiquadState->coefs[3] is -B2 27 pBiquadState->coefs[4] is -B1, these are in Q15 format 28 29 DELAYS- 30 pBiquadState->pDelays[0] is x(n-1)L in Q0 format 31 pBiquadState->pDelays[1] is x(n-2)L in Q0 format 32 pBiquadState->pDelays[2] is y(n-1)L in Q0 format 33 pBiquadState->pDelays[3] is y(n-2)L in Q0 format 34 ***************************************************************************/ 35 36 void BQ_1I_D16F16C15_TRC_WRA_01 ( Biquad_Instance_t *pInstance, 37 LVM_INT16 *pDataIn, 38 LVM_INT16 *pDataOut, 39 LVM_INT16 NrSamples) 40 { 41 LVM_INT32 ynL; 42 LVM_INT16 ii; 43 PFilter_State pBiquadState = (PFilter_State) pInstance; 44 45 for (ii = NrSamples; ii != 0; ii--) 46 { 47 48 49 /************************************************************************** 50 PROCESSING OF THE LEFT CHANNEL 51 ***************************************************************************/ 52 // ynL=A2 (Q15) * x(n-2)L (Q0) in Q15 53 ynL=(LVM_INT32)pBiquadState->coefs[0]* pBiquadState->pDelays[1]; 54 55 // ynL+=A1 (Q15) * x(n-1)L (Q0) in Q15 56 ynL+=(LVM_INT32)pBiquadState->coefs[1]* pBiquadState->pDelays[0]; 57 58 // ynL+=A0 (Q15) * x(n)L (Q0) in Q15 59 ynL+=(LVM_INT32)pBiquadState->coefs[2]* (*pDataIn); 60 61 // ynL+= (-B2 (Q15) * y(n-2)L (Q0) ) in Q15 62 ynL+=(LVM_INT32)pBiquadState->coefs[3]*pBiquadState->pDelays[3]; 63 64 // ynL+= (-B1 (Q15) * y(n-1)L (Q0) ) in Q15 65 ynL+=(LVM_INT32)pBiquadState->coefs[4]*pBiquadState->pDelays[2]; 66 67 ynL=ynL>>15; // ynL in Q0 format 68 /************************************************************************** 69 UPDATING THE DELAYS 70 ***************************************************************************/ 71 pBiquadState->pDelays[3]=pBiquadState->pDelays[2]; // y(n-2)L=y(n-1)L 72 pBiquadState->pDelays[1]=pBiquadState->pDelays[0]; // x(n-2)L=x(n-1)L 73 pBiquadState->pDelays[2]=ynL; // Update y(n-1)L in Q0 74 pBiquadState->pDelays[0]=(*pDataIn++); // Update x(n-1)L in Q0 75 76 /************************************************************************** 77 WRITING THE OUTPUT 78 ***************************************************************************/ 79 *pDataOut++=(LVM_INT16)ynL; // Write Left output in Q0 80 81 82 } 83 84 } 85 86
