//---------------------------------------------------------------------------

#ifndef LowPassPrototypesH
#define LowPassPrototypesH

#include <complex>

#define MAX_POLE_COUNT 20
#define ARRAY_DIM 50      // This MUST be at least 2*MAX_POLE_COUNT because some filter polys are defined in terms of 2 * NumPoles

namespace kitiirfir
{

enum TOurSortTypes{stMax, stMin};

// These coeff form H(s) = (N2*s^2 + N1*s + N0) / (D2*s^2 + D1*s + D0)
// NumSections is the number of 1st and 2nd order polynomial factors .
struct TSPlaneCoeff { double N2[ARRAY_DIM]; double N1[ARRAY_DIM]; double N0[ARRAY_DIM];
                   double D2[ARRAY_DIM]; double D1[ARRAY_DIM]; double D0[ARRAY_DIM];
                   int NumSections; };

// These are the available filter polynomials. NOT_IIR is for code testing.
enum TFilterPoly {BUTTERWORTH, GAUSSIAN, BESSEL, ADJUSTABLE, CHEBYSHEV,
               INVERSE_CHEBY, PAPOULIS, ELLIPTIC, NOT_IIR};

// This structure defines the low pass filter prototype.
// The 3 dB corner frequency is 1 rad/sec for all filters.
struct TLowPassParams {TFilterPoly ProtoType;  // Butterworth, Cheby, etc.
                    int NumPoles;           // Pole count
                    double Ripple;          // Passband Ripple for the Elliptic and Chebyshev
                    double StopBanddB;      // Stop Band Attenuation in dB for the Elliptic and Inverse Cheby
                    double Gamma;           // Controls the transition bandwidth on the Adjustable Gauss. -1 <= Gamma <= 1
                   };


TSPlaneCoeff CalcLowPassProtoCoeff(TLowPassParams Filt);
void SetCornerFreq(int Count, double *D2, double *D1, double *D0, double *N2, double *N1, double *N0);
int GetFilterCoeff(int RootCount, std::complex<double> *Roots, double *A2, double *A1, double *A0);
int RebuildPoly(int PolyCount, double *PolyCoeff, double *A2, double *A1, double *A0 );
void SortRootsByZeta(std::complex<double> *Roots, int Count, TOurSortTypes SortType);
bool HeapIndexSort(double *Data, int *Index, int N, TOurSortTypes SortType);

} // namespace

#endif