qf_filter.h

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/***************************************************************************
                               qf_filter.h
                             ----------------
    begin                : Mon Jan 02 2006
    copyright            : (C) 2006 by Vincent Habchi, F5RCS
    email                : 10.50@free.fr
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef _QF_FILTER_H
#define _QF_FILTER_H

// Header for filter

enum qf_filter_type
{
  LOWPASS,
  HIGHPASS,
  BANDPASS,
  BANDSTOP
};

typedef enum qf_filter_type qft;

enum qf_filter_kind
{
  BUTT,
  CHEB,
  ICHEB,
  BESS,
  CAUER,
  UNDEF
};

typedef enum qf_filter_kind qfk;

enum qf_ctype
{
  CAP,
  IND,
  RES
};

typedef enum qf_ctype qfct;

struct qf_comp
{
  qfct comp;
  qf_double_t val;
  unsigned node1;
  unsigned node2;
};

typedef struct qf_comp qfc;

// Generic filter class

class qf_filter
{
 protected:
  const qft type;       // Lowpass, highpass...
  const qfk kind;       // Butterworth, Chebichev...
  unsigned ord;         // Order of filter

  const qf_double_t fc;     // Cutoff / Center
  qf_double_t bw;           // Bandwidth
  const qf_double_t imp;    // Terminating impedance
  qf_double_t fstart;           // Start frequency
  qf_double_t fstop;            // Stop frequency

  // Polynomial description

  qf_poly E;            // H(w) = E(w)/P(w)
  qf_poly F;            // D(w) = F(w)/P(w)
  qf_poly P;

  qf_poly BN;           // B(w) susceptance of filter
  qf_poly BD;           // B(w) susceptance of filter

  unsigned ncomp;       // Number of components
  qfc * Comp;           // Table of components

public:
  qf_filter (void);     // Default init
  qf_filter (int);      // Init
  qf_filter (qfk, qft);
  qf_filter (int, qfk, qft);
  qf_filter (qfk, qft, qf_double_t, qf_double_t, qf_double_t);
  virtual ~qf_filter (void);    // Exit

  // Common routines to perform extraction of poles and zeros

  // This one extracts a finite pole of transmission
  void extract_pole_pCsLC (qf_double_t, qfc *, qf_double_t);

  int order (void) { return ord; }

  virtual void synth (qft) = 0; // Synthesize filter

  std::string to_qucs (void);   // Outputs Qucs
  std::string to_spice (void);  // Outputs SPICE
  void dump_qucs (void);        // Outputs Qucs to std::cout
  void dump_spice (void);   // Outputs SPICE to std::cout
  void dump_cout (void);    // Outputs to std::cout

private:
  std::string num2str (qf_double_t);
};

#endif // _QF_FILTER_H