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#ifndef _BIQUADFILTER_H
#define _BIQUADFILTER_H
/**
* Unit_BiquadFilter implements a second order IIR filter.
*
* @author (C) 2002 Phil Burk, SoftSynth.com, All Rights Reserved
*/
#define BIQUAD_MIN_RATIO (0.000001)
#define BIQUAD_MIN_Q (0.00001)
typedef struct BiquadFilter_s
{
double xn1; // storage for delayed signals
double xn2;
double yn1;
double yn2;
double a0; // coefficients
double a1;
double a2;
double b1;
double b2;
double cos_omega;
double sin_omega;
double alpha;
} BiquadFilter;
void BiquadFilter_SetupHighPass( BiquadFilter *filter, double ratio, double Q );
void BiquadFilter_SetupNotch( BiquadFilter *filter, double ratio, double Q );
void BiquadFilter_Filter( BiquadFilter *filter, float *inputs, float *outputs, int numSamples );
#endif
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