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_SetTarget                                                 */
25/*                                                                      */
26/* DESCRIPTION:                                                         */
27/*  This function updates the private instance parameters: Shift,Target,*/
28/*  Current for a given Audio Stream based on new value of TargetGain   */
29/*                                                                      */
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   */
39/*                    for an Audio Stream                               */
40/*  TargetGain      - TargetGain value in Q 16.15 format                */
41/*                                                                      */
42/* RETURNS:                                                             */
43/*  void                                                                */
44/*                                                                      */
45/************************************************************************/
46
47void LVC_Mixer_SetTarget(LVMixer3_st *pStream,
48                        LVM_INT32           TargetGain)
49{
50    LVM_INT32       Shift=0;
51    LVM_INT32       CurrentGain;
52    LVM_INT32       MaxGain=TargetGain;                     // MaxGain is in Q16.15 format
53    Mix_Private_st  *pInstance=(Mix_Private_st *)pStream->PrivateParams;
54    CurrentGain=pInstance->Current>>(16-pInstance->Shift);  // CurrentGain in Q16.15 format
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