1/*
2 * Copyright (c) 2011-2015, Intel Corporation
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without modification,
6 * are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation and/or
13 * other materials provided with the distribution.
14 *
15 * 3. Neither the name of the copyright holder nor the names of its contributors
16 * may be used to endorse or promote products derived from this software without
17 * specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
21 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
23 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
26 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#pragma once
32
33#include "LinearParameterAdaptation.h"
34#include <cmath>
35#include <limits>
36
37/**
38 * This class is used to perform a logarithmic adapation of type:
39 * (slopeNumerator / slopeDenominator) * log(parameter) + offset
40 * Since log(x) == -INFINITY , we can define FloorValue as a
41 *       x -> 0
42 * a lower bound limit for the adaptation
43 */
44class CLogarithmicParameterAdaptation : public CLinearParameterAdaptation
45{
46public:
47    CLogarithmicParameterAdaptation();
48
49    /**
50     * Conversions must satisfy the following: f(f'(a)) = a
51     * Let f=fromUserValue and f'=toUserValue
52     * if y = f(log(x)/log(base)), then
53     * f'(y) * log(base) = log (x)
54     * exp(f'(y)*log(base)) = x
55     */
56    virtual int64_t fromUserValue(double dValue) const;
57    virtual double toUserValue(int64_t iValue) const;
58
59    virtual void showProperties(std::string &strResult) const;
60
61    virtual bool fromXml(const CXmlElement &xmlElement, CXmlSerializingContext &serializingContext);
62
63private:
64    /**
65     * _dLogarithmBase characterizes the new logarithm logB(x) with
66     * the following property: logB(x) = log(x) / log(_dLogarithmBase).
67     * log being the base-e logarithm.
68     *
69     * std::exp(1) == e^1 == e == natural logarithm base
70     * Make sure there is no precision lose by using std::exp overload that
71     * return the same type as _dLogarithmBase
72     */
73    double _dLogarithmBase{std::exp(decltype(_dLogarithmBase){1})};
74    /**
75     * _dFloorValue reflects the lower bound for volume attenuation
76     */
77    double _dFloorValue{-std::numeric_limits<double>::infinity()};
78};
79