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#ifndef LS_FILTER_H
#define LS_FILTER_H
#include <util/biquad.h>
#define FILT_MIDI_2_FREQ(m) (m * 80.0f + 10.0f)
#define FILT_MIDI_2_RESO(m) (m * 0.00787f)
#define LSF_BW 0.9
#define LSF_FB 0.9f
typedef struct {
biquad filt;
biquad bp_filt;
bq_t scale;
bq_t resonance;
} ls_filt;
typedef enum {
LS_FILT_TYPE_LP = 0,
LS_FILT_TYPE_BP = 1,
LS_FILT_TYPE_HP = 2
} ls_filt_type;
static inline void ls_filt_init(ls_filt *f)
{
biquad_init(&(f->filt));
biquad_init(&(f->bp_filt));
}
static inline void ls_filt_setup(ls_filt *f, ls_filt_type t, bq_t cutoff,
bq_t resonance, bq_t fs)
{
bp_set_params(&(f->bp_filt), cutoff, 0.7, fs);
switch(t) {
case LS_FILT_TYPE_LP:
lp_set_params(&(f->filt), cutoff, 1.0 - resonance * LSF_BW, fs);
break;
case LS_FILT_TYPE_BP:
bp_set_params(&(f->filt), cutoff, 1.0 - resonance * LSF_BW, fs);
break;
case LS_FILT_TYPE_HP:
hp_set_params(&(f->filt), cutoff, 1.0 - resonance * LSF_BW, fs);
break;
default:
/* oops, its not a known type - should really happen, but
lets make the output silent just in case */
lp_set_params(&(f->filt), 1.0, 1.0, fs);
break;
}
f->scale = 1.0f - resonance * 0.7f;
f->resonance = resonance;
}
static inline bq_t ls_filt_run(ls_filt *f, bq_t in)
{
return biquad_run(&(f->filt), in) * f->scale +
biquad_run_fb(&(f->bp_filt), in, f->resonance * LSF_FB) *
f->resonance;
}
#endif
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