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/* rc~.c by Martin Peach 20100315 */
/* Pd external emulating a resistor-capacitor low-pass filter */
/* The control parameter is a time constant in seconds (or resistance X capacitance) */
#include "m_pd.h"
static t_class *rc_tilde_class;
typedef struct _rc_tilde
{
t_object rc_obj;
t_float rc_rc;
t_float rc_f;
t_sample rc_node;
} t_rc_tilde;
static t_int *rc_tilde_perform(t_int *w);
static void rc_tilde_dsp(t_rc_tilde *x, t_signal **sp);
static void *rc_tilde_new(t_floatarg f);
static t_int *rc_tilde_perform(t_int *w)
{
t_rc_tilde *x = (t_rc_tilde *)(w[1]);
t_sample *in = (t_sample *)(w[2]);
t_sample *out = (t_sample *)(w[3]);
int n = (int)(w[4]);
float slewrate;
float sp = 1.0/sys_getsr();
if (x->rc_rc < sp) slewrate = 1.0;
else slewrate = sp/x->rc_rc;
while (n--)
{
x->rc_node += (*in++ - x->rc_node)*slewrate;
*out++ = x->rc_node;
}
return (w+5);
}
static void rc_tilde_dsp(t_rc_tilde *x, t_signal **sp)
{
dsp_add(rc_tilde_perform, 4, x, sp[0]->s_vec, sp[1]->s_vec, sp[0]->s_n);
}
static void *rc_tilde_new(t_floatarg f)
{
t_rc_tilde *x = (t_rc_tilde *)pd_new(rc_tilde_class);
x->rc_rc = f;
x->rc_node = 0.0;
floatinlet_new (&x->rc_obj, &x->rc_rc);
outlet_new(&x->rc_obj, &s_signal);
return (void *)x;
}
void rc_tilde_setup(void)
{
rc_tilde_class = class_new(gensym("rc~"),
(t_newmethod)rc_tilde_new,
0, sizeof(t_rc_tilde),
CLASS_DEFAULT,
A_DEFFLOAT, 0);
class_addmethod(rc_tilde_class, (t_method)rc_tilde_dsp, gensym("dsp"), 0);
CLASS_MAINSIGNALIN(rc_tilde_class, t_rc_tilde, rc_f);
}
/* fin rc~.c */
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