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_1I_D16F16Css_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 29 DELAYS- 30 pBiquadState->pDelays[0] is x(n-1)L in Q0 format 31 pBiquadState->pDelays[1] is y(n-1)L in Q0 format 32 ***************************************************************************/ 33 34 void FO_1I_D16F16C15_TRC_WRA_01( Biquad_Instance_t *pInstance, 35 LVM_INT16 *pDataIn, 36 LVM_INT16 *pDataOut, 37 LVM_INT16 NrSamples) 38 { 39 LVM_INT32 ynL; 40 LVM_INT16 ii; 41 PFilter_State pBiquadState = (PFilter_State) pInstance; 42 43 for (ii = NrSamples; ii != 0; ii--) 44 { 45 46 /************************************************************************** 47 PROCESSING OF THE LEFT CHANNEL 48 ***************************************************************************/ 49 // ynL=A1 (Q15) * x(n-1)L (Q0) in Q15 50 ynL=(LVM_INT32)pBiquadState->coefs[0]* pBiquadState->pDelays[0]; 51 52 // ynL+=A0 (Q15) * x(n)L (Q0) in Q15 53 ynL+=(LVM_INT32)pBiquadState->coefs[1]* (*pDataIn); 54 55 // ynL+= (-B1 (Q15) * y(n-1)L (Q0) ) in Q15 56 ynL+=(LVM_INT32)pBiquadState->coefs[2]*pBiquadState->pDelays[1]; 57 58 59 ynL=(LVM_INT16)(ynL>>15); // ynL in Q0 format 60 /************************************************************************** 61 UPDATING THE DELAYS 62 ***************************************************************************/ 63 pBiquadState->pDelays[1]=ynL; // Update y(n-1)L in Q0 64 pBiquadState->pDelays[0]=(*pDataIn++); // Update x(n-1)L in Q0 65 66 /************************************************************************** 67 WRITING THE OUTPUT 68 ***************************************************************************/ 69 *pDataOut++=(LVM_INT16)ynL; // Write Left output in Q0 70 71 } 72 73 } 74 75
