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282 lines
8.1 KiB
282 lines
8.1 KiB
/* GSL - Generic Sound Layer
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* Copyright (C) 2001 Stefan Westerfeld and Tim Janik
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General
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* Public License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __GSL_FILTER_H__
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#define __GSL_FILTER_H__
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#include <gsl/gslmath.h>
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#ifdef __cplusplus
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extern "C" {
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#endif /* __cplusplus */
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/* --- transformations --- */
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static inline GslComplex gsl_trans_s2z (GslComplex s);
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static inline double gsl_trans_freq2s (double w);
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static inline double gsl_trans_zepsilon2ss (double epsilon);
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/* --- filter roots and poles --- */
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void gsl_filter_butter_rp (unsigned int iorder,
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double freq, /* 0..pi */
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double epsilon,
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GslComplex *roots, /* [0..iorder-1] */
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GslComplex *poles);
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void gsl_filter_tscheb1_rp (unsigned int iorder,
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double freq, /* 0..pi */
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double epsilon,
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GslComplex *roots, /* [0..iorder-1] */
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GslComplex *poles);
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void gsl_filter_tscheb2_rp (unsigned int iorder,
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double c_freq, /* 0..pi */
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double steepness,
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double epsilon,
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GslComplex *roots, /* [0..iorder-1] */
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GslComplex *poles);
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/* --- tschebyscheff type II steepness --- */
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double gsl_filter_tscheb2_steepness_db (unsigned int iorder,
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double c_freq,
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double epsilon,
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double stopband_db);
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double gsl_filter_tscheb2_steepness (unsigned int iorder,
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double c_freq,
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double epsilon,
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double residue);
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/* --- lowpass filters --- */
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void gsl_filter_butter_lp (unsigned int iorder,
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double freq, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb1_lp (unsigned int iorder,
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double freq, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb2_lp (unsigned int iorder,
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double c_freq, /* 0..pi */
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double steepness,
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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/* --- highpass filters --- */
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void gsl_filter_butter_hp (unsigned int iorder,
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double freq, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb1_hp (unsigned int iorder,
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double freq, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb2_hp (unsigned int iorder,
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double c_freq, /* 0..pi */
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double steepness,
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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/* --- bandpass filters --- */
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void gsl_filter_butter_bp (unsigned int iorder,
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double freq1, /* 0..pi */
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double freq2, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb1_bp (unsigned int iorder,
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double freq1, /* 0..pi */
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double freq2, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb2_bp (unsigned int iorder,
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double freq1, /* 0..pi */
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double freq2, /* 0..pi */
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double steepness,
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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/* --- bandstop filters --- */
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void gsl_filter_butter_bs (unsigned int iorder,
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double freq1, /* 0..pi */
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double freq2, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb1_bs (unsigned int iorder,
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double freq1, /* 0..pi */
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double freq2, /* 0..pi */
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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void gsl_filter_tscheb2_bs (unsigned int iorder,
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double freq1, /* 0..pi */
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double freq2, /* 0..pi */
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double steepness,
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double epsilon,
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double *a, /* [0..iorder] */
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double *b);
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/* --- FIR Filters --- */
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void gsl_filter_fir_approx (unsigned int iorder,
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double *a, /* [0..iorder] */
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unsigned int n_points,
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const double *freq,
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const double *value);
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/* --- IIR Filter Evaluation --- */
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typedef struct {
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guint order;
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gdouble *a; /* [0..order] */
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gdouble *b; /* [0..order] */
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gdouble *w; /* [0..2*order] */
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} GslIIRFilter;
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void gsl_iir_filter_setup (GslIIRFilter *f,
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guint order,
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const gdouble *a,
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const gdouble *b,
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gdouble *buffer); /* 4*(order+1) */
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void gsl_iir_filter_change (GslIIRFilter *f,
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guint order,
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const gdouble *a,
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const gdouble *b,
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gdouble *buffer); /* 4*(order+1) */
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void gsl_iir_filter_eval (GslIIRFilter *f,
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guint n_values,
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const gfloat *x,
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gfloat *y);
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/* --- Biquad Filters --- */
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typedef enum /*< skip >*/
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{
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GSL_BIQUAD_NORMALIZE_PASSBAND,
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GSL_BIQUAD_NORMALIZE_RESONANCE_GAIN,
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GSL_BIQUAD_NORMALIZE_PEAK_GAIN
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} GslBiquadNormalize;
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typedef enum /*< skip >*/
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{
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GSL_BIQUAD_RESONANT_LOWPASS = 1,
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GSL_BIQUAD_RESONANT_HIGHPASS,
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GSL_BIQUAD_LOWSHELVE,
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GSL_BIQUAD_HIGHSHELVE,
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GSL_BIQUAD_PEAK
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} GslBiquadType;
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typedef struct {
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GslBiquadType type;
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GslBiquadNormalize normalize; /* high/low pass */
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gfloat f_fn;
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gfloat gain;
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gfloat quality; /* peak/notch */
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guint dirty : 1; /* post filter_config() changes? */
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guint approx_values : 1; /* biquad_config_approx_*() called? */
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/*< private >*/
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gdouble k, v;
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} GslBiquadConfig;
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typedef struct {
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gdouble xc0, xc1, xc2;
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gdouble yc1, yc2; /* yc0==1 */
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gdouble xd1, xd2, yd1, yd2; /* history */
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} GslBiquadFilter;
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void gsl_biquad_config_init (GslBiquadConfig *c,
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GslBiquadType type,
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GslBiquadNormalize normalize);
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void gsl_biquad_config_setup (GslBiquadConfig *c,
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gfloat f_fn,
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gfloat gain,
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gfloat quality);
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void gsl_biquad_config_approx_freq (GslBiquadConfig *c,
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gfloat f_fn);
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void gsl_biquad_config_approx_gain (GslBiquadConfig *c,
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gfloat gain);
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void gsl_biquad_filter_config (GslBiquadFilter *f,
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GslBiquadConfig *c,
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gboolean reset_state);
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void gsl_biquad_filter_eval (GslBiquadFilter *f,
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guint n_values,
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const gfloat *x,
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gfloat *y);
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/* --- filter scanning -- */
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gdouble gsl_filter_sine_scan (guint order,
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const gdouble *a,
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const gdouble *b,
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gdouble freq,
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guint n_values);
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/* --- implementations --- */
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static inline GslComplex
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gsl_trans_s2z (GslComplex s)
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{
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/* 1 + (Td/2) * s
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* z = ----------------
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* 1 - (Td/2) * s
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*/
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GslComplex one = { 1, 0 };
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return gsl_complex_div (gsl_complex_add (one, s), gsl_complex_sub (one, s));
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/* return gsl_complex_div (gsl_complex_sub (s, one), gsl_complex_add (s, one)); */
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}
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static inline double
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gsl_trans_freq2s (double w)
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{
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return tan (w / 2.);
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}
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static inline double
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gsl_trans_zepsilon2ss (double zepsilon)
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{
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double e2 = (1.0 - zepsilon) * (1.0 - zepsilon);
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/* 1___ _________________
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* | \ | 1.0
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* |-----\<---- 1 - zepsilon zepsilon = \ | ----------------
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* |_______\________________ \| 1 + sepsilon^2
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*/
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return sqrt ((1.0 - e2) / e2);
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}
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static inline double
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gsl_trans_freq2z (double w)
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{
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return atan (w) * 2.;
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}
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#ifdef __cplusplus
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}
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#endif /* __cplusplus */
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#endif /* __GSL_FILTER_H__ */
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