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//----------------------------------------------------------------
//  縦続形 IIR フィルタ（Biquad クラスを使用）
//  Class for IIR filter of cascade structure using Biquad class
//  2015/09/03, Copyright (c) 2015 MIKAMI, Naoki
//----------------------------------------------------------------

#ifndef IIR_CASCADE_HPP
#define IIR_CASCADE_HPP

#include "Biquad.hpp"

namespace Mikami
{
    template<int order> class IirCascade
    {
    public:
    
        // constructor
        IirCascade(const Biquad::Coefs ck[], float g0) : g0_(g0) 
        {
            for (int n=0; n<order/2; n++)
                hk_[n] = new Biquad(ck[n]);
            Clear();
        }
    
        // destructor
        ~IirCascade()
        {
            for  (int n=0; n<order/2; n++) delete hk_[n];
        }
        
        // clear internal buffer
        void Clear()
        {
            for (int k=0; k<order/2; k++) hk_[k]->Clear();
        }

        // execute filter
        float Execute(float xn)
        {
            float yn = g0_*xn;
            for (int k=0; k<order/2; k++) yn = hk_[k]->Execute(yn);
            return yn;
        }

    private:
        Biquad* hk_[order/2];   // biquad IIR filter
        const float g0_;        // gain factor

        // disallow copy constructor and assignment operator
        IirCascade(const IirCascade&);
        IirCascade& operator = (const IirCascade&);
   };
}
#endif  // IIR_CASCADE_HPP