libsidplayfp  1.5.3
ZeroOrderResampler.h
1 /*
2  * This file is part of libsidplayfp, a SID player engine.
3  *
4  * Copyright 2011-2013 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 ZEROORDER_RESAMPLER_H
23 #define ZEROORDER_RESAMPLER_H
24 
25 #include "Resampler.h"
26 
27 namespace reSIDfp
28 {
29 
36 {
37 
38 private:
39  int cachedSample;
40 
41  const int cyclesPerSample;
42  int sampleOffset;
43  int outputValue;
44 
45 public:
46  ZeroOrderResampler(double clockFrequency, double samplingFrequency) :
47  cachedSample(0),
48  cyclesPerSample((int)(clockFrequency / samplingFrequency * 1024.)),
49  sampleOffset(0),
50  outputValue(0) {}
51 
52  bool input(int sample)
53  {
54  bool ready = false;
55 
56  if (sampleOffset < 1024)
57  {
58  outputValue = cachedSample + (sampleOffset * (sample - cachedSample) >> 10);
59  ready = true;
60  sampleOffset += cyclesPerSample;
61  }
62 
63  sampleOffset -= 1024;
64 
65  cachedSample = sample;
66 
67  return ready;
68  }
69 
70  int output() const { return outputValue; }
71 
72  void reset()
73  {
74  sampleOffset = 0;
75  cachedSample = 0;
76  }
77 };
78 
79 } // namespace reSIDfp
80 
81 #endif