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// lowpassfilter.h
/******************************************************************************
*
* MiXViews - an X window system based sound & data editor/processor
*
* Copyright (c) 1993, 1994 Regents of the University of California
*
* Author: Douglas Scott
* Date: December 13, 1994
*
* Permission to use, copy and modify this software and its documentation
* for research and/or educational purposes and without fee is hereby granted,
* provided that the above copyright notice appear in all copies and that
* both that copyright notice and this permission notice appear in
* supporting documentation. The author reserves the right to distribute this
* software and its documentation. The University of California and the author
* make no representations about the suitability of this software for any
* purpose, and in no event shall University of California be liable for any
* damage, loss of data, or profits resulting from its use.
* It is provided "as is" without express or implied warranty.
*
******************************************************************************/
// this does f(x) = g1x + g2[x-1] [first order recursive filter]
#ifndef LOWPASSFILTER_H
#ifdef __GNUG__
#pragma interface
#endif
#define LOWPASSFILTER_H
#include "processfun.h"
class Requester;
class LowPassFilter : public SimpleFunction {
typedef SimpleFunction Super;
friend class LowPassRequester;
public:
LowPassFilter(Data* output);
LowPassFilter(Data* output, double feedback);
redefined const char* message() { return "Filtering..."; }
redefined double operator () (double input);
redefined void restoreState();
protected:
redefined Requester* createRequester();
redefined void initialize();
private:
void clear() { past = 0; }
void setCoefficients(double *gn1, double *gn2);
private:
double cutoff;
double gain;
double g1; // these are initialized in ctor
double g2;
double past;
boolean firstTime;
};
#endif
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