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/* Copyright (c) 2003 krzYszcz and others.
* For information on usage and redistribution, and for a DISCLAIMER OF ALL
* WARRANTIES, see the file, "LICENSE.txt," in this distribution. */
/* This filter (cmusic's nres and csound's resonr) originates from
CMJv6n4 article by Smith & Angell. See also section 9.6 of
``Introduction to Digital Filters'' by Smith. */
/* CHECKME if creation args (or defaults) restored after signal disconnection */
#include <math.h>
#include "m_pd.h"
#include "shared.h"
#include "sickle/sic.h"
#if defined(_WIN32) || defined(__APPLE__)
/* cf pd/src/x_arithmetic.c */
#define expf exp
#define cosf cos
#endif
#define RESON_DEFQ .01
#define RESON_MINQ 1e-20 /* CHECKME */
#define RESON_MINOMEGA .0001 /* CHECKME */
#define RESON_MAXOMEGA SHARED_PI /* CHECKME */
typedef struct _reson
{
t_sic x_sic;
float x_srcoef;
float x_xnm1;
float x_xnm2;
float x_ynm1;
float x_ynm2;
} t_reson;
static t_class *reson_class;
static void reson_clear(t_reson *x)
{
x->x_xnm1 = x->x_xnm2 = x->x_ynm1 = x->x_ynm2 = 0.;
}
/* LATER make ready for optional audio-rate modulation
(separate scalar case routines, use sic_makecostable(), etc.) */
static t_int *reson_perform(t_int *w)
{
t_reson *x = (t_reson *)(w[1]);
int nblock = (int)(w[2]);
t_float *xin = (t_float *)(w[3]);
t_float *gin = (t_float *)(w[4]);
t_float fin0 = *(t_float *)(w[5]);
t_float qin0 = *(t_float *)(w[6]);
t_float *out = (t_float *)(w[7]);
float xnm1 = x->x_xnm1;
float xnm2 = x->x_xnm2;
float ynm1 = x->x_ynm1;
float ynm2 = x->x_ynm2;
/* CHECKME sampled once per block */
float qinv = (qin0 > RESON_MINQ ? -1. / qin0 : (-1. / RESON_MINQ));
float omega = fin0 * x->x_srcoef;
float radius, c1, c2, scale;
if (omega < RESON_MINOMEGA)
omega = RESON_MINOMEGA;
else if (omega > RESON_MAXOMEGA)
omega = RESON_MAXOMEGA;
radius = expf(omega * qinv); /* radius < 1 (because omega * qinv < 0) */
c1 = 2. * radius * cosf(omega);
c2 = radius * radius;
scale = 1. - radius;
while (nblock--)
{
float yn, xn = *xin++;
/* CHECKED gain control */
*out++ = yn =
*gin++ * scale * (xn - radius * xnm2) + c1 * ynm1 - c2 * ynm2;
xnm2 = xnm1;
xnm1 = xn;
ynm2 = ynm1;
ynm1 = yn;
}
x->x_xnm1 = xnm1;
x->x_xnm2 = xnm2;
/* LATER rethink */
x->x_ynm1 = (PD_BIGORSMALL(ynm1) ? 0. : ynm1);
x->x_ynm2 = (PD_BIGORSMALL(ynm2) ? 0. : ynm2);
return (w + 8);
}
static void reson_dsp(t_reson *x, t_signal **sp)
{
x->x_srcoef = SHARED_2PI / sp[0]->s_sr;
reson_clear(x);
dsp_add(reson_perform, 7, x, sp[0]->s_n,
sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, sp[3]->s_vec,
sp[4]->s_vec);
}
static void *reson_new(t_floatarg f1, t_floatarg f2, t_floatarg f3)
{
t_reson *x = (t_reson *)pd_new(reson_class);
x->x_srcoef = SHARED_2PI / sys_getsr();
if (f1 < 0.) f1 = 0.;
if (f2 < 0.) f2 = 0.;
if (f3 <= 0.)
f3 = RESON_DEFQ; /* CHECKED */
sic_newinlet((t_sic *)x, f1);
sic_newinlet((t_sic *)x, f2);
sic_newinlet((t_sic *)x, f3);
outlet_new((t_object *)x, &s_signal);
reson_clear(x);
return (x);
}
void reson_tilde_setup(void)
{
reson_class = class_new(gensym("reson~"),
(t_newmethod)reson_new, 0,
sizeof(t_reson), 0,
A_DEFFLOAT, A_DEFFLOAT, A_DEFFLOAT, 0);
sic_setup(reson_class, reson_dsp, SIC_FLOATTOSIGNAL);
class_addmethod(reson_class, (t_method)reson_clear, gensym("clear"), 0);
}
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