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revised version of F746_SD_GraphicEqualizer
Dependencies: BSP_DISCO_F746NG F746_GUI F746_SAI_IO FrequencyResponseDrawer LCD_DISCO_F746NG SDFileSystem_Warning_Fixed TS_DISCO_F746NG mbed
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Diff: MyClasses_Functions/BiquadGrEq.hpp
- Revision:
- 0:e953eb392151
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MyClasses_Functions/BiquadGrEq.hpp Wed Apr 27 13:56:39 2016 +0000 @@ -0,0 +1,66 @@ +//-------------------------------------------------------------- +// グラフィックイコライザで使う 1D タイプの 2 次のフィルタ +// Biquad filter of 1D type for graphic equalizer +// このクラスでは,係数は実行中に書き換えられることを想定している +// +// u[n] = x[n] + a1*u[n-1] + a2*u[n-2] +// y[n] = b0*u[n] + b1*u[n-1] + b2*u[n-2] +// x[n] : input signal +// y[n] : output signal +// +// 2016/03/25, Copyright (c) 2016 MIKAMI, Naoki +//-------------------------------------------------------------- + +#ifndef IIR_BIQUAD_HPP +#define IIR_BIQUAD_HPP + +#include "mbed.h" + +// 2nd order IIR filter +namespace Mikami +{ + class BiquadGrEq + { + public: + struct Coefs { float a1, a2, b0, b1, b2; }; + + BiquadGrEq() {} // Default constructore + + BiquadGrEq(const Coefs ck) + { + SetCoefficients(ck); + Clear(); + } + + void SetCoefficients(const Coefs ck) + { + a1_ = ck.a1; + a2_ = ck.a2; + b0_ = ck.b0; + b1_ = ck.b1; + b2_ = ck.b2; + } + + float Execute(float xn) + { + float un = xn + a1_*un1_ + a2_*un2_; + float yn = b0_*un + b1_*un1_ + b2_*un2_; + + un2_ = un1_; + un1_ = un; + + return yn; + } + + void Clear() { un1_ = un2_ = 0; } + + private: + float a1_, a2_, b0_, b1_, b2_; + float un1_, un2_; + + // disallow copy constructor + BiquadGrEq(const BiquadGrEq&); + }; +} +#endif // IIR_BIQUAD_HPP +