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 "FO_2I_D16F32Css_LShx_TRC_WRA_01_Private.h" 20 #include "LVM_Macros.h" 21 22 /************************************************************************** 23 ASSUMPTIONS: 24 COEFS- 25 pBiquadState->coefs[0] is A1, 26 pBiquadState->coefs[1] is A0, 27 pBiquadState->coefs[2] is -B1, these are in Q15 format 28 pBiquadState->Shift is Shift value 29 DELAYS- 30 pBiquadState->pDelays[0] is x(n-1)L in Q15 format 31 pBiquadState->pDelays[1] is y(n-1)L in Q30 format 32 pBiquadState->pDelays[2] is x(n-1)R in Q15 format 33 pBiquadState->pDelays[3] is y(n-1)R in Q30 format 34 ***************************************************************************/ 35 36 void FO_2I_D16F32C15_LShx_TRC_WRA_01(Biquad_Instance_t *pInstance, 37 LVM_INT16 *pDataIn, 38 LVM_INT16 *pDataOut, 39 LVM_INT16 NrSamples) 40 { 41 LVM_INT32 ynL,ynR; 42 LVM_INT32 Temp; 43 LVM_INT32 NegSatValue; 44 LVM_INT16 ii; 45 LVM_INT16 Shift; 46 PFilter_State pBiquadState = (PFilter_State) pInstance; 47 48 NegSatValue = LVM_MAXINT_16 +1; 49 NegSatValue = -NegSatValue; 50 51 Shift = pBiquadState->Shift; 52 53 54 for (ii = NrSamples; ii != 0; ii--) 55 { 56 57 /************************************************************************** 58 PROCESSING OF THE LEFT CHANNEL 59 ***************************************************************************/ 60 61 // ynL =A1 (Q15) * x(n-1)L (Q15) in Q30 62 ynL=(LVM_INT32)pBiquadState->coefs[0]* pBiquadState->pDelays[0]; 63 // ynR =A1 (Q15) * x(n-1)R (Q15) in Q30 64 ynR=(LVM_INT32)pBiquadState->coefs[0]* pBiquadState->pDelays[2]; 65 66 67 // ynL+=A0 (Q15) * x(n)L (Q15) in Q30 68 ynL+=(LVM_INT32)pBiquadState->coefs[1]* (*pDataIn); 69 // ynR+=A0 (Q15) * x(n)L (Q15) in Q30 70 ynR+=(LVM_INT32)pBiquadState->coefs[1]* (*(pDataIn+1)); 71 72 73 // ynL += (-B1 (Q15) * y(n-1)L (Q30) ) in Q30 74 MUL32x16INTO32(pBiquadState->pDelays[1],pBiquadState->coefs[2],Temp,15); 75 ynL +=Temp; 76 // ynR += (-B1 (Q15) * y(n-1)R (Q30) ) in Q30 77 MUL32x16INTO32(pBiquadState->pDelays[3],pBiquadState->coefs[2],Temp,15); 78 ynR +=Temp; 79 80 81 /************************************************************************** 82 UPDATING THE DELAYS 83 ***************************************************************************/ 84 pBiquadState->pDelays[1]=ynL; // Update y(n-1)L in Q30 85 pBiquadState->pDelays[0]=(*pDataIn++); // Update x(n-1)L in Q15 86 87 pBiquadState->pDelays[3]=ynR; // Update y(n-1)R in Q30 88 pBiquadState->pDelays[2]=(*pDataIn++); // Update x(n-1)R in Q15 89 90 /************************************************************************** 91 WRITING THE OUTPUT 92 ***************************************************************************/ 93 /*Apply shift: Instead of left shift on 16-bit result, right shift of (15-shift) is applied 94 for better SNR*/ 95 ynL = ynL>>(15-Shift); 96 ynR = ynR>>(15-Shift); 97 98 /*Saturate results*/ 99 if(ynL > LVM_MAXINT_16) 100 { 101 ynL = LVM_MAXINT_16; 102 } 103 else 104 { 105 if(ynL < NegSatValue) 106 { 107 ynL = NegSatValue; 108 } 109 } 110 111 if(ynR > LVM_MAXINT_16) 112 { 113 ynR = LVM_MAXINT_16; 114 } 115 else 116 { 117 if(ynR < NegSatValue) 118 { 119 ynR = NegSatValue; 120 } 121 } 122 123 *pDataOut++=(LVM_INT16)ynL; 124 *pDataOut++=(LVM_INT16)ynR; 125 } 126 127 } 128 129
