/*

    File: MeterTable.cpp

Abstract: Class for handling conversion from linear scale to dB

 Version: 1.4.3

Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

Inc. ("Apple") in consideration of your agreement to the following

terms, and your use, installation, modification or redistribution of

this Apple software constitutes acceptance of these terms.  If you do

not agree with these terms, please do not use, install, modify or

redistribute this Apple software.

In consideration of your agreement to abide by the following terms, and

subject to these terms, Apple grants you a personal, non-exclusive

license, under Apple's copyrights in this original Apple software (the

"Apple Software"), to use, reproduce, modify and redistribute the Apple

Software, with or without modifications, in source and/or binary forms;

provided that if you redistribute the Apple Software in its entirety and

without modifications, you must retain this notice and the following

text and disclaimers in all such redistributions of the Apple Software.

Neither the name, trademarks, service marks or logos of Apple Inc. may

be used to endorse or promote products derived from the Apple Software

without specific prior written permission from Apple.  Except as

expressly stated in this notice, no other rights or licenses, express or

implied, are granted by Apple herein, including but not limited to any

patent rights that may be infringed by your derivative works or by other

works in which the Apple Software may be incorporated.

The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,

MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED

AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),

STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

Copyright (C) 2014 Apple Inc. All Rights Reserved.

*/

#include "MeterTable.h"

inline double DbToAmp(double inDb)

{

    return pow(10., 0.05 * inDb);

}

MeterTable::MeterTable(float inMinDecibels, size_t inTableSize, float inRoot)

    : mMinDecibels(inMinDecibels),

    mDecibelResolution(mMinDecibels / (inTableSize - 1)), 

    mScaleFactor(1. / mDecibelResolution)

{

    if (inMinDecibels >= 0.)

    {

        printf("MeterTable inMinDecibels must be negative");

        return;

    }

    mTable = (float*)malloc(inTableSize*sizeof(float));

    double minAmp = DbToAmp(inMinDecibels);

    double ampRange = 1. - minAmp;

    double invAmpRange = 1. / ampRange;

    double rroot = 1. / inRoot;

    for (size_t i = 0; i < inTableSize; ++i) {

        double decibels = i * mDecibelResolution;

        double amp = DbToAmp(decibels);

        double adjAmp = (amp - minAmp) * invAmpRange;

        mTable[i] = pow(adjAmp, rroot);

    }

}

MeterTable::~MeterTable()

{

    free(mTable);

}