| /* |
| * 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 "LVM_Types.h" |
| #include "LVM_Macros.h" |
| #include "LVC_Mixer_Private.h" |
| |
| /************************************************************************/ |
| /* FUNCTION: */ |
| /* LVMixer3_SetTimeConstant */ |
| /* */ |
| /* DESCRIPTION: */ |
| /* This function calculates the step change for fractional gain for a */ |
| /* given time constant, sample rate and num channels */ |
| /* Delta=(2147483647*4*1000)/(NumChannels*SampleRate*Tc_millisec) */ |
| /* in Q 0.31 format */ |
| /* */ |
| /* PARAMETERS: */ |
| /* pStream - ptr to Instance Parameter Structure LVMixer3_st for an*/ |
| /* Audio Stream */ |
| /* Tc_millisec - TimeConstant i.e time required in milli second to */ |
| /* go from linear fractional gain of 0 to 0.99999999 */ |
| /* Fs - LVM_Fs_en enumerator for Sampling Frequency */ |
| /* NumChannels - Number of channels in Audio Stream 1=Mono, 2=Stereo */ |
| /* */ |
| /* UPDATES: */ |
| /* Delta - the step change for fractional gain per 4 samples */ |
| /* in Q0.31 format for a given Time Constant, */ |
| /* Sample Rate and NumChannels */ |
| /* RETURNS: */ |
| /* void */ |
| /************************************************************************/ |
| #ifdef BUILD_FLOAT |
| void LVC_Mixer_SetTimeConstant(LVMixer3_FLOAT_st *pStream, |
| LVM_INT32 Tc_millisec, |
| LVM_Fs_en Fs, |
| LVM_INT16 NumChannels) |
| { |
| #ifdef HIGHER_FS |
| LVM_FLOAT DeltaTable[11] = {0.500000f,/*8000*/ |
| 0.362812f,/*11025*/ |
| 0.333333f,/*12000*/ |
| 0.250000f,/*16000*/ |
| 0.181406f,/*22050*/ |
| 0.166666f,/*24000*/ |
| 0.125000f,/*32000*/ |
| 0.090703f,/*44100*/ |
| 0.083333f,/*48000*/ |
| 0.041667f,/*96000*/ |
| 0.020833f};/*192000*/ |
| #else |
| LVM_FLOAT DeltaTable[9] = {0.500000f,/*8000*/ |
| 0.362812f,/*11025*/ |
| 0.333333f,/*12000*/ |
| 0.250000f,/*16000*/ |
| 0.181406f,/*22050*/ |
| 0.166666f,/*24000*/ |
| 0.125000f,/*32000*/ |
| 0.090703f,/*44100*/ |
| 0.083333f};/*48000*/ |
| #endif |
| |
| Mix_Private_FLOAT_st *pInstance = (Mix_Private_FLOAT_st *)pStream->PrivateParams; |
| LVM_FLOAT Delta = DeltaTable[Fs]; |
| Delta = Delta / (NumChannels); |
| |
| if(Tc_millisec == 0) |
| Delta = 1.000000f; |
| else |
| Delta = Delta / Tc_millisec; |
| |
| if(Delta == 0) |
| Delta = 0.0000000005f; /* If Time Constant is so large that Delta is 0, \ |
| assign minimum value to Delta */ |
| pInstance->Delta = Delta; // Delta=(2147483647*4*1000)/(NumChannels*SampleRate*Tc_millisec) |
| } |
| #else |
| void LVC_Mixer_SetTimeConstant(LVMixer3_st *pStream, |
| LVM_INT32 Tc_millisec, |
| LVM_Fs_en Fs, |
| LVM_INT16 NumChannels) |
| { |
| LVM_INT32 DeltaTable[9]={1073741824, |
| 779132389, |
| 715827882, |
| 536870912, |
| 389566194, |
| 357913941, |
| 268435456, |
| 194783097, |
| 178956971}; |
| Mix_Private_st *pInstance=(Mix_Private_st *)pStream->PrivateParams; |
| LVM_INT32 Delta=DeltaTable[Fs]; |
| Delta=Delta>>(NumChannels-1); |
| |
| if(Tc_millisec==0) |
| Delta=0x7FFFFFFF; |
| else |
| Delta=Delta/Tc_millisec; |
| |
| if(Delta==0) |
| Delta=1; // If Time Constant is so large that Delta is 0, assign minimum value to Delta |
| |
| pInstance->Delta=Delta; // Delta=(2147483647*4*1000)/(NumChannels*SampleRate*Tc_millisec) in Q 0.31 format |
| } |
| #endif |