libsidplayfp 1.0.3
ZeroOrderResampler.h
00001 /*
00002  * This file is part of libsidplayfp, a SID player engine.
00003  *
00004  * Copyright 2011-2013 Leandro Nini <drfiemost@users.sourceforge.net>
00005  * Copyright 2007-2010 Antti Lankila
00006  *
00007  * This program is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 2 of the License, or
00010  * (at your option) any later version.
00011  *
00012  * This program is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU General Public License
00018  * along with this program; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
00020  */
00021 
00022 #ifndef ZEROORDER_RESAMPLER_H
00023 #define ZEROORDER_RESAMPLER_H
00024 
00025 #include "Resampler.h"
00026 
00027 namespace reSIDfp
00028 {
00029 
00035 class ZeroOrderResampler : public Resampler
00036 {
00037 
00038 private:
00039     int cachedSample;
00040 
00041     const int cyclesPerSample;
00042     int sampleOffset;
00043     int outputValue;
00044 
00045 public:
00046     ZeroOrderResampler(double clockFrequency, double samplingFrequency) :
00047         cachedSample(0),
00048         cyclesPerSample((int)(clockFrequency / samplingFrequency * 1024.)),
00049         sampleOffset(0),
00050         outputValue(0) {}
00051 
00052     bool input(int sample)
00053     {
00054         bool ready = false;
00055 
00056         if (sampleOffset < 1024)
00057         {
00058             outputValue = cachedSample + (sampleOffset * (sample - cachedSample) >> 10);
00059             ready = true;
00060             sampleOffset += cyclesPerSample;
00061         }
00062 
00063         sampleOffset -= 1024;
00064 
00065         cachedSample = sample;
00066 
00067         return ready;
00068     }
00069 
00070     int output() const { return outputValue; }
00071 
00072     void reset()
00073     {
00074         sampleOffset = 0;
00075         cachedSample = 0;
00076     }
00077 };
00078 
00079 } // namespace reSIDfp
00080 
00081 #endif