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 "LVM_Types.h"
19#include "LVM_Macros.h"
20#include "LVC_Mixer_Private.h"
21
22/************************************************************************/
23/* FUNCTION:                                                            */
24/*   LVMixer3_Init                                                      */
25/*                                                                      */
26/* DESCRIPTION:                                                         */
27/*  This intialization function intializes the private instance         */
28/*  paramters for a given Audio Stream based on TargetGain and          */
29/*  CurrentGain                                                         */
30/*  This function caclulates the "Shift" required to provide the        */
31/*  integer part of TargetGain and fractional gain values "Target" and  */
32/*  "Current" based on maximum(TargetGain,CurrentGain)                  */
33/*  E.g. CurrentGain=1.9 and TargetGain=2.5 then based on               */
34/*  MaxGain of 2.5, Shift = 2, Current=1.9/4=0.475, Target=2.5/4=0.625  */
35/*  Therefore integer gain of 4 is provided by Left Shift of 2 and      */
36/*  fraction gain is provided through Current=0.475 and Target=0.625    */
37/* PARAMETERS:                                                          */
38/*  pStream     - ptr to Instance Parameter Structure LVMixer3_st for an*/
39/*                Audio Stream                                          */
40/*  TargetGain  - TargetGain value in Q 16.15 format                    */
41/*  CurrentGain - CurrentGain value in Q 16.15 format                   */
42/*                                                                      */
43/* RETURNS:                                                             */
44/*  void                                                                */
45/*                                                                      */
46/************************************************************************/
47
48void LVC_Mixer_Init( LVMixer3_st *pStream,
49                    LVM_INT32           TargetGain,
50                    LVM_INT32           CurrentGain)
51{
52    LVM_INT16       Shift=0;
53    LVM_INT32       MaxGain=TargetGain;         // MaxGain is in Q16.15 format
54    Mix_Private_st  *pInstance=(Mix_Private_st *)pStream->PrivateParams;
55    if(CurrentGain>MaxGain)
56        MaxGain=CurrentGain;                    // MaxGain=max(CurrentGain,TargetGain)
57
58    MaxGain=MaxGain>>15;                        // MaxGain in Q31.0 format i.e Integer part only
59    while(MaxGain>0){                           // Update Shift required to provide integer gain
60        Shift++;
61        MaxGain=MaxGain>>1;
62    }
63    pInstance->Target=TargetGain<<(16-Shift);   // Update fractional gain Target
64    pInstance->Current=CurrentGain<<(16-Shift); // Update fractional gain Current
65    pInstance->Shift=Shift;                     // Update Shift
66}
67
68