/*
  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