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/*
* moog vcf, 4-pole lowpass resonant filter
*
* (c) Edward Kelly 2012
* BSD License
*/
#include "m_pd.h"
#include <math.h>
#define _limit 0.95
static t_class *mvcf_tilde_class;
typedef struct _mvcf_tilde {
t_object x_obj;
t_float b0, b1, b2, b3, b4; //filter buffers to keep (beware denormals!)
t_float token, debug, safety;
t_outlet *lp;
} t_mvcf_tilde;
/* We could have a mode where the fc and res are only registered at the start of the block (quick) or are registered in signal mode (slow) - i.e. a flag */
static inline float saturate( float input ) { //clamp without branching
float x1 = fabsf( input + _limit );
float x2 = fabsf( input - _limit );
return 0.5 * (x1 - x2);
}
t_int *mvcf_tilde_perform(t_int *w) {
t_mvcf_tilde *x = (t_mvcf_tilde *)(w[1]);
t_sample *in = (t_sample *)(w[2]);
t_sample *fc = (t_sample *)(w[3]);
t_sample *res = (t_sample *)(w[4]);
t_sample *out = (t_sample *)(w[5]);
int n = (int)(w[6]);
//x *b0 =
/*
q = 1.0f - frequency;
p = frequency + 0.8f * frequency * q;
f = p + p - 1.0f;
q = resonance * (1.0f + 0.5f * q * (1.0f - q + 5.6f * q * q));
*/
// while (n--) {
// float f = *(in++);
// setup_svf(obj, *(freq++), *(res++));
// *(out++) = run_svf(obj, f + ((obj->b) * (*(res++))));
// }
float t1 = 0;
float t2 = 0;
float xb0 = x->b0;
float xb1 = x->b1;
float xb2 = x->b2;
float xb3 = x->b3;
float xb4 = x->b4;
float i1 = 0;
float fc1 = 0;
float res1 = 0;
float q = 0;
float p = 0;
float fcoeff = 0;
// while (n-=4) {
while (n--) {
i1=(*in++);
fc1 = (*fc++);
/* This failsafe line stops the filter bursting
* ...but it is expensive! */
if(x->safety) {
fc1 = fc1 <= 1 ? fc1 >= 0 ? fc1 : 0 : 1;
}
res1 = (*res++);
q = 1.0f - fc1;
p = fc1 + 0.8f * fc1 * q;
fcoeff = p + p - 1.0f;
q = res1 * (1.0f + 0.5f * q * (1.0f - q + 5.6f * q * q));
i1 -= q * xb4; //feedback
t1 = xb1;
xb1 = (i1 + xb0) * p - xb1 * fcoeff;
t2 = xb2;
xb2 = (xb1 + t1) * p - xb2 * fcoeff;
t1 = xb3;
xb3 = (xb2 + t2) * p - xb3 * fcoeff;
xb4 = (xb3 + t1) * p - xb4 * fcoeff;
xb4 = saturate(xb4);
xb4 = xb4 - xb4 * xb4 * xb4 * 0.01f;
xb0 = i1;
*out++ = xb4; // lowpass mode
// *out++ = i1 - x->b4; // highpass mode
// Lowpass output: xb4
// Highpass output: in - xb4;
// Bandpass output: 3.0f * (b3 - xb4);
}
x->b0 = xb0;
x->b1 = xb1;
x->b2 = xb2;
x->b3 = xb3;
x->b4 = xb4;
if(x->debug != 0) {
x->token +=1;
if(x->token == 15) {
post("q = %f, p=%f, fcoeff=%f, b0=%f, b1=%f, b2=%f, b3=%f, b4=%f",q,p,fcoeff,xb0,xb1,xb2,xb3,xb4);
x->token = 0;
}
}
return (w+7);
}
void mvcf_tilde_dsp(t_mvcf_tilde *x, t_signal **sp) {
dsp_add(mvcf_tilde_perform, 6, x, sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, sp[3]->s_vec, sp[0]->s_n);
}
void mvcf_tilde_safety(t_mvcf_tilde *x, t_floatarg f) {
x->safety = f != 0 ? 1 : 0;
}
/*void mvcf_tilde_mode(t_mvcf_tilde *x, t_floatarg f) {
x->mode = f < 1 ? 0 : f > 1 ? 2 : 1;
}
*/
void mvcf_tilde_clear(t_mvcf_tilde *x) {
x->b0 = 0;
x->b1 = 0;
x->b2 = 0;
x->b3 = 0;
x->b4 = 0;
}
void mvcf_tilde_debug(t_mvcf_tilde *x, t_floatarg f) {
x->debug = f != 0 ? 1 : 0;
}
void *mvcf_tilde_new(t_floatarg f) {
t_mvcf_tilde *x = (t_mvcf_tilde *)pd_new(mvcf_tilde_class);
x->b0 = 0;
x->b1 = 0;
x->b2 = 0;
x->b3 = 0;
x->b4 = 0;
x->token = 0;
x->safety = 1;
inlet_new (&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
inlet_new (&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
outlet_new(&x->x_obj, &s_signal);
return (void *)x;
}
void mvcf_tilde_setup(void) {
mvcf_tilde_class = class_new(gensym("mvcf~"),
(t_newmethod)mvcf_tilde_new,
0, sizeof(t_mvcf_tilde),
CLASS_DEFAULT, A_DEFFLOAT, 0);
post("~~~~~~~~~~~~~~~>mvcf~");
post("~~~>by Ed Kelly, 2012");
class_addmethod(mvcf_tilde_class,
(t_method)mvcf_tilde_dsp, gensym("dsp"), 0);
CLASS_MAINSIGNALIN(mvcf_tilde_class, t_mvcf_tilde, token);
class_addmethod(mvcf_tilde_class, (t_method)mvcf_tilde_clear, gensym("clear"), 0);
class_addmethod(mvcf_tilde_class, (t_method)mvcf_tilde_debug, gensym("debug"), 0);
class_addmethod(mvcf_tilde_class, (t_method)mvcf_tilde_safety, gensym("safe"), 0);
// class_addmethod(mvcf_tilde_class, (t_method)mvcf_tilde_mode, gensym("mode"), A_DEFFLOAT, 0);
}
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