/******************************************************************************/
/* iir.h
/******************************************************************************/
#ifndef IIR_H
#define IIR_H

#define	pi			3.1415926535897932384626433832795

#define IIR_FILTERTYPE_UNKNOWN     0x00000000
#define IIR_FILTERTYPE_LOWPASS     0x00000001
#define IIR_FILTERTYPE_HIGHPASS    0x00000002
#define IIR_FILTERTYPE_BANDPASS    0x00000003
#define IIR_FILTERTYPE_BANDSTOP    0x00000004
#define IIR_FILTERTYPE_PEAKING     0x00000005
#define IIR_FILTERTYPE_LOWSHELF    0x00000006
#define IIR_FILTERTYPE_HIGHSHELF   0x00000007


/******************************************************************************/
typedef struct _sComplex
{
	double pRealData, pImagData;
} Complex;

typedef struct _sIIRCoeff
{

	double ak0, ak1, ak2;
	double bk0, bk1, bk2;
	double xn1, xn2;
	double yn1, yn2;

}IIRCOEFF;

typedef struct _sIIRParam
{
	/* General Params */
	double fg, Qf;

	/* for shelving EQs */
	double beta;

	/* for peaking and shelving EQs */
	double A;
}IIRPARAM;

/******************************************************************************/
#ifdef __cplusplus
extern "C" {
#endif

void IIRInit(struct _sIIRCoeff *pCoeff, unsigned order);
int IIRCalcPartFilterCoeff1(struct _sIIRCoeff *pCoeff, double fa, double fg, double qp, unsigned filterType);
int IIRCalcPartFilterCoeff2(struct _sIIRCoeff *pCoeff, double A, double fa, double fg, double qp, unsigned filterType);
void IIRCalcFilterCoeff(struct _sIIRCoeff *pCoeff, double fa, double fg, double q, unsigned order, unsigned filterType);

double IIRBilTrans(double fg, double fa);
double IIRCalcQp(unsigned p, unsigned N);
void IIR(struct _sIIRCoeff *pCoeff, double *xn, double *yn, unsigned order, unsigned numPoints);
void IIRPrintCoeff(FILE *pFile, struct _sIIRCoeff *pCoeff, unsigned N);
void ScaleCoeff(struct _sIIRCoeff *pCoeff);
double MinMag(double val1, double val2);
double MaxMag(double val1, double val2);

#ifdef __cplusplus
}
#endif
#endif // IIR_H
/******************************************************************************/