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/********************* -*- mode: C; coding: utf-8 -*- *************************/
/**
* \file linFirFilter.h
* \brief Interface to Linear IIR Filter interpolation functions.
* \author Copyright (C) 2006-2022 Ralf Hoppe <ralf.hoppe@dfcgen.de>
*
******************************************************************************/
#ifndef LINFIR_FILTER_H
#define LINFIR_FILTER_H
/* INCLUDE FILES **************************************************************/
#include "dfcgen.h"
#ifdef __cplusplus
extern "C" {
#endif
/* GLOBAL TYPE DECLARATIONS ***************************************************/
/** Typical smoothing windows used in digital signal processing.
*/
typedef enum
{
LINFIR_DSPWIN_RECT = 0,
LINFIR_DSPWIN_HAMMING,
LINFIR_DSPWIN_VANHANN,
LINFIR_DSPWIN_BLACKMAN,
LINFIR_DSPWIN_KAISER,
LINFIR_DSPWIN_SIZE
} LINFIR_DSPWIN;
/** Linear FIR filter types.
*/
typedef enum
{
LINFIR_TYPE_RECT = 0, /**< Rectangular lowpass */
LINFIR_TYPE_COS, /**< Cosinus lowpass */
LINFIR_TYPE_COS2, /**< Square cosinus lowpass */
LINFIR_TYPE_GAUSS, /**< Gaussian lowpass */
LINFIR_TYPE_SQR, /**< Squared 1st order lowpass */
LINFIR_TYPE_SIZE
} LINFIR_TYPE;
/** Linear FIR filter design constraints.
* \see DESIGNDLG_COMMON
*/
typedef struct
{
LINFIR_TYPE type; /**< Filter type. \attention Must be the 1st element */
int order; /**< Order of filter. \attention Must be the 2nd element */
double cutoff; /**< Cutoff frequency. \attention Must be the 3rd element */
FTRDESIGN ftr; /**< Frequency transformation data. \attention Must be the 4th element */
LINFIR_DSPWIN dspwin; /**< Type of smoothing window */
double winparm; /**< Parameter of window, e.g. Kaiser alpha */
} LINFIR_DESIGN;
/* GLOBAL CONSTANT DECLARATIONS ***********************************************/
/* GLOBAL VARIABLE DECLARATIONS ***********************************************/
/* GLOBAL MACRO DEFINITIONS ***************************************************/
/* EXPORTED FUNCTIONS *********************************************************/
/* FUNCTION *******************************************************************/
/** Generates a linear FIR filter. The cutoff frequency always is assumed to be
* the 3dB point of magnitude response.
*
* \param pDesign Pointer to linear FIR filter design data.
* \param pFilter Pointer to buffer which gets the generated filter.
* Notice, that memory space for polynomials will be
* allocated.
*
* \return Zero on success, else an error number (see errno.h or
* gsl_errno.h for predefined codes).
******************************************************************************/
int linFirFilterGen (LINFIR_DESIGN *pDesign, FLTCOEFF *pFilter);
#ifdef __cplusplus
}
#endif
#endif /* LINFIR_FILTER_H */
/******************************************************************************/
/* END OF FILE */
/******************************************************************************/
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