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

#include <stdio.h>

#ifndef pi
#define	pi			3.1415926535897932384626433832795
#endif

#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


/******************************************************************************/
#ifndef iir_float_t
#define iir_float_t float
#endif

typedef struct _sComplex
{
	iir_float_t pRealData, pImagData;
} Complex;

typedef struct _siir_coef_t
{

	iir_float_t ak0, ak1, ak2;
	iir_float_t bk0, bk1, bk2;

} iir_coef_t;

typedef struct _siir_state_t
{

	iir_float_t xn1, xn2;
	iir_float_t yn1, yn2;

} iir_state_t;

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

	/* for shelving EQs */
	iir_float_t beta;

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

typedef struct _siir_lin_t
{
	unsigned order;
	iir_float_t *pX, *pY;
} iir_lin_t;


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

void IIRInit(iir_state_t *pState, unsigned order);
int IIRCalcPartFilterCoeff1(iir_coef_t *pCoeff, iir_float_t fa, iir_float_t fg, iir_float_t qp, unsigned filterType);
int IIRCalcPartFilterCoeff2(iir_coef_t *pCoeff, iir_float_t A, iir_float_t fa, iir_float_t fg, iir_float_t qp, unsigned filterType);
void IIRCalcFilterCoeff(iir_coef_t *pCoeff, iir_float_t fa, iir_float_t fg, iir_float_t q, unsigned order, unsigned filterType);

iir_float_t IIRBilTrans(iir_float_t fg, iir_float_t fa);
iir_float_t IIRCalcQp(unsigned p, unsigned N);
void IIR(iir_state_t *pState, iir_coef_t *pCoeff, iir_float_t *xn, iir_float_t *yn, unsigned order, unsigned numPoints);
iir_float_t IIRS(iir_state_t *pState, iir_coef_t *pCoeff, iir_float_t xn, unsigned order);

void IIRSSE(iir_coef_t *pCoeff, iir_float_t *xn, iir_float_t *yn, unsigned order, unsigned numPoints);
void IIRPrintCoeff(FILE *pFile, iir_coef_t *pCoeff, unsigned N);
void ScaleCoeff(iir_coef_t *pCoeff);
iir_float_t MinMag(iir_float_t val1, iir_float_t val2);
iir_float_t MaxMag(iir_float_t val1, iir_float_t val2);

void IIR_lin_init(iir_lin_t *pObj, unsigned order);
void IIR_lin_free(iir_lin_t *pObj);
iir_float_t IIR_lin_process(iir_lin_t *pObj, iir_float_t *pB, iir_float_t *pA, iir_float_t x);

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