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/*
* cheby.c - chebyshev polynomial evaluation
* Copyright (c) 2000-2003 by Tom Schouten
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "m_pd.h"
#include <math.h>
#define MAX_ORDER 1024
#define DEFAULT_ORDER 4
typedef struct chebyctl
{
t_float c_gain[MAX_ORDER];
t_int c_order;
} t_chebyctl;
typedef struct cheby
{
t_object x_obj;
t_float x_f;
t_chebyctl x_ctl;
} t_cheby;
static void cheby_bang(t_cheby *x)
{
}
static void cheby_coef(t_cheby *x, t_floatarg coef, t_floatarg f)
{
int i = (int)coef;
if ((i > 0) && (i < x->x_ctl.c_order + 1)){
x->x_ctl.c_gain[i-1] = f;
/* post("cheby: harmonic %d set to %f", i, f); */
}
}
static t_int *cheby_perform(t_int *w)
{
t_float *in = (float *)(w[3]);
t_float *out = (float *)(w[4]);
t_chebyctl *ctl = (t_chebyctl *)(w[1]);
t_float *gain = ctl->c_gain;
t_int i;
t_int n = (t_int)(w[2]), k;
t_float x,y,t1,t2,t,acc;
for (i = 0; i < n; i++)
{
x = *in++;
gain = ctl->c_gain;
t2 = 1; /* T_0 */
t1 = x; /* T_1 */
acc = *gain++ * x; /* a_1 T_1 */
for (k=2; k<=ctl->c_order; k++){
t = 2*x*t1 - t2; /* T_k = 2 x T_{k-1} - T_{k-2} */
acc += *gain++ * t; /* a_k T_k */
t2 = t1;
t1 = t;
}
*out++ = acc;
}
return (w+5);
}
static void cheby_dsp(t_cheby *x, t_signal **sp)
{
dsp_add(cheby_perform, 4, &x->x_ctl, sp[0]->s_n, sp[0]->s_vec, sp[1]->s_vec);
}
static void cheby_free(void)
{
}
t_class *cheby_class;
static void *cheby_new(t_floatarg order_f)
{
int i;
int order = (int)order_f;
t_cheby *x = (t_cheby *)pd_new(cheby_class);
outlet_new(&x->x_obj, gensym("signal"));
if (order < 1) order = DEFAULT_ORDER; /* default */
if (order > MAX_ORDER) order = MAX_ORDER; /* maximum */
//post("cheby: order = %d", order);
x->x_ctl.c_order = order;
cheby_coef(x, 1, 1);
for (i=2; i<order+1; i++){
cheby_coef(x, 0, i);
}
return (void *)x;
}
void cheby_tilde_setup(void)
{
//post("cheby~ v0.1");
cheby_class = class_new(gensym("cheby~"), (t_newmethod)cheby_new,
(t_method)cheby_free, sizeof(t_cheby), 0, A_DEFFLOAT, 0);
CLASS_MAINSIGNALIN(cheby_class, t_cheby, x_f);
class_addmethod(cheby_class, (t_method)cheby_bang, gensym("bang"), 0);
class_addmethod(cheby_class, (t_method)cheby_dsp, gensym("dsp"), 0);
class_addmethod(cheby_class, (t_method)cheby_coef, gensym("coef"), A_DEFFLOAT, A_DEFFLOAT, 0);
}
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