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46 lines
2.0 KiB
C++
46 lines
2.0 KiB
C++
//---------------------------------------------------------------------------
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#ifndef LowPassPrototypesH
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#define LowPassPrototypesH
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#include <complex>
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#define MAX_POLE_COUNT 20
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#define ARRAY_DIM 50 // This MUST be at least 2*MAX_POLE_COUNT because some filter polys are defined in terms of 2 * NumPoles
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namespace kitiirfir
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{
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enum TOurSortTypes{stMax, stMin};
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// These coeff form H(s) = (N2*s^2 + N1*s + N0) / (D2*s^2 + D1*s + D0)
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// NumSections is the number of 1st and 2nd order polynomial factors .
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struct TSPlaneCoeff { double N2[ARRAY_DIM]; double N1[ARRAY_DIM]; double N0[ARRAY_DIM];
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double D2[ARRAY_DIM]; double D1[ARRAY_DIM]; double D0[ARRAY_DIM];
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int NumSections; };
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// These are the available filter polynomials. NOT_IIR is for code testing.
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enum TFilterPoly {BUTTERWORTH, GAUSSIAN, BESSEL, ADJUSTABLE, CHEBYSHEV,
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INVERSE_CHEBY, PAPOULIS, ELLIPTIC, NOT_IIR};
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// This structure defines the low pass filter prototype.
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// The 3 dB corner frequency is 1 rad/sec for all filters.
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struct TLowPassParams {TFilterPoly ProtoType; // Butterworth, Cheby, etc.
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int NumPoles; // Pole count
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double Ripple; // Passband Ripple for the Elliptic and Chebyshev
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double StopBanddB; // Stop Band Attenuation in dB for the Elliptic and Inverse Cheby
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double Gamma; // Controls the transition bandwidth on the Adjustable Gauss. -1 <= Gamma <= 1
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};
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TSPlaneCoeff CalcLowPassProtoCoeff(TLowPassParams Filt);
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void SetCornerFreq(int Count, double *D2, double *D1, double *D0, double *N2, double *N1, double *N0);
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int GetFilterCoeff(int RootCount, std::complex<double> *Roots, double *A2, double *A1, double *A0);
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int RebuildPoly(int PolyCount, double *PolyCoeff, double *A2, double *A1, double *A0 );
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void SortRootsByZeta(std::complex<double> *Roots, int Count, TOurSortTypes SortType);
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bool HeapIndexSort(double *Data, int *Index, int N, TOurSortTypes SortType);
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} // namespace
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#endif
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