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/*
ZynAddSubFX - a software synthesizer
Analog Filter.h - Several analog filters (lowpass, highpass...)
Copyright (C) 2002-2005 Nasca Octavian Paul
Author: Nasca Octavian Paul
This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License
as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License (version 2) for more details.
You should have received a copy of the GNU General Public License (version 2)
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef ANALOG_FILTER_H
#define ANALOG_FILTER_H
#include "../globals.h"
#include "Filter_.h"
class AnalogFilter:public Filter_{
public:
AnalogFilter(unsigned char Ftype,REALTYPE Ffreq, REALTYPE Fq,unsigned char Fstages);
~AnalogFilter();
void filterout(REALTYPE *smp);
void setfreq(REALTYPE frequency);
void setfreq_and_q(REALTYPE frequency,REALTYPE q_);
void setq(REALTYPE q_);
void settype(int type_);
void setgain(REALTYPE dBgain);
void setstages(int stages_);
void cleanup();
REALTYPE H(REALTYPE freq);//Obtains the response for a given frequency
private:
struct fstage{
REALTYPE c1,c2;
} x[MAX_FILTER_STAGES+1],y[MAX_FILTER_STAGES+1],
oldx[MAX_FILTER_STAGES+1],oldy[MAX_FILTER_STAGES+1];
void singlefilterout(REALTYPE *smp,fstage &x,fstage &y,REALTYPE *c,REALTYPE *d);
void computefiltercoefs();
int type;//The type of the filter (LPF1,HPF1,LPF2,HPF2...)
int stages;//how many times the filter is applied (0->1,1->2,etc.)
REALTYPE freq;//Frequency given in Hz
REALTYPE q; //Q factor (resonance or Q factor)
REALTYPE gain;//the gain of the filter (if are shelf/peak) filters
int order;//the order of the filter (number of poles)
REALTYPE c[3],d[3];//coefficients
REALTYPE oldc[3],oldd[3];//old coefficients(used only if some filter paremeters changes very fast, and it needs interpolation)
REALTYPE xd[3],yd[3];//used if the filter is applied more times
int needsinterpolation,firsttime;
int abovenq;//this is 1 if the frequency is above the nyquist
int oldabovenq;//if the last time was above nyquist (used to see if it needs interpolation)
};
#endif
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