libsidplayfp 2.3.0
Resampler.h
1/*
2 * This file is part of libsidplayfp, a SID player engine.
3 *
4 * Copyright 2011-2020 Leandro Nini <drfiemost@users.sourceforge.net>
5 * Copyright 2007-2010 Antti Lankila
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 */
21
22#ifndef RESAMPLER_H
23#define RESAMPLER_H
24
25#include <cmath>
26
27#include "sidcxx11.h"
28
29#include "siddefs-fp.h"
30
31namespace reSIDfp
32{
33
39{
40protected:
41 inline short softClip(int x) const
42 {
43 constexpr int threshold = 28000;
44 if (likely(x < threshold))
45 return x;
46
47 constexpr double t = threshold / 32768.;
48 constexpr double a = 1. - t;
49 constexpr double b = 1. / a;
50
51 double value = static_cast<double>(x - threshold) / 32768.;
52 value = t + a * tanh(b * value);
53 return static_cast<short>(value * 32768.);
54 }
55
56 virtual int output() const = 0;
57
58 Resampler() {}
59
60public:
61 virtual ~Resampler() {}
62
69 virtual bool input(int sample) = 0;
70
76 short getOutput() const
77 {
78 return softClip(output());
79 }
80
81 virtual void reset() = 0;
82};
83
84} // namespace reSIDfp
85
86#endif
Definition Resampler.h:39
short getOutput() const
Definition Resampler.h:76
virtual bool input(int sample)=0