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/*
* 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.
*/
/************************************************************************/
/* */
/* Project:: */
/* $Author: beq07716 $*/
/* $Revision: 1000 $*/
/* $Date: 2010-06-28 13:08:20 +0200 (Mon, 28 Jun 2010) $*/
/* */
/************************************************************************/
#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
}
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