ref: c29ae6d779ecb2785219f14837e63dcbcefffb3f
dir: /src/biquad.h/
#ifndef biquad_included
#define biquad_included
#include <math.h>
#include "st_i.h"
/* Private data for the biquad filter effects */
typedef struct biquad
{
double gain;
double fc; /* Centre/corner/cutoff frequency */
union {double q, bandwidth, slope;} width; /* Depending on filter type */
bool dcNormalise; /* A treble filter should normalise at DC */
double b2, b1, b0; /* Filter coefficients */
double a2, a1, a0; /* Filter coefficients */
st_sample_t i1, i2; /* Filter memory */
double o1, o2; /* Filter memory */
} * biquad_t;
int st_biquad_start(eff_t effp, char const * width_name);
int st_biquad_flow(eff_t effp, const st_sample_t *ibuf, st_sample_t *obuf,
st_size_t *isamp, st_size_t *osamp);
assert_static(sizeof(struct biquad) <= ST_MAX_EFFECT_PRIVSIZE,
/* else */ biquad_PRIVSIZE_too_big);
#endif