text: /*
   * 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_Init                                                      */
  /*                                                                      */
  /* DESCRIPTION:                                                         */
  /*  This intialization function intializes the private instance         */
  /*  paramters for a given Audio Stream based on TargetGain and          */
  /*  CurrentGain                                                         */
  /*  This function caclulates the "Shift" required to provide the        */
  /*  integer part of TargetGain and fractional gain values "Target" and  */
  /*  "Current" based on maximum(TargetGain,CurrentGain)                  */
  /*  E.g. CurrentGain=1.9 and TargetGain=2.5 then based on               */
  /*  MaxGain of 2.5, Shift = 2, Current=1.9/4=0.475, Target=2.5/4=0.625  */
  /*  Therefore integer gain of 4 is provided by Left Shift of 2 and      */
  /*  fraction gain is provided through Current=0.475 and Target=0.625    */
  /* PARAMETERS:                                                          */
  /*  pStream     - ptr to Instance Parameter Structure LVMixer3_st for an*/
  /*                Audio Stream                                          */
  /*  TargetGain  - TargetGain value in Q 16.15 format                    */
  /*  CurrentGain - CurrentGain value in Q 16.15 format                   */
  /*                                                                      */
  /* RETURNS:                                                             */
  /*  void                                                                */
  /*                                                                      */
  /************************************************************************/
  
  void LVC_Mixer_Init( LVMixer3_st *pStream,
                      LVM_INT32           TargetGain,
                      LVM_INT32           CurrentGain)
  {
      LVM_INT16       Shift=0;
      LVM_INT32       MaxGain=TargetGain;         // MaxGain is in Q16.15 format
      Mix_Private_st  *pInstance=(Mix_Private_st *)pStream->PrivateParams;
      if(CurrentGain>MaxGain)
          MaxGain=CurrentGain;                    // MaxGain=max(CurrentGain,TargetGain)
  
      MaxGain=MaxGain>>15;                        // MaxGain in Q31.0 format i.e Integer part only
      while(MaxGain>0){                           // Update Shift required to provide integer gain
          Shift++;
          MaxGain=MaxGain>>1;
      }
      pInstance->Target=TargetGain<<(16-Shift);   // Update fractional gain Target
      pInstance->Current=CurrentGain<<(16-Shift); // Update fractional gain Current
      pInstance->Shift=Shift;                     // Update Shift
  }
  
  