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/* Lattice IIR filter from PARCOR coefficients
* Copyright (C) 2005 Nicolas Chetry <okin@altern.org>
* and Edward Kelly <morph_2016@yahoo.co.uk>
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "m_pd.h"
static t_class *lpreson_tilde_class;
typedef struct _lpreson_control
{
t_float *c_residual, *c_output;
t_atom *x_parcors;
/* t_atom x_parc_interp_one[MAXPOLES];
t_int x_parc_ord_one;
t_atom x_parc_interp_two[MAXPOLES];
t_int x_parc_ord_two; */
} t_lpreson_control;
typedef struct _lpreson_tilde
{
t_object x_obj;
t_float f_dummy;
t_int x_order;
t_lpreson_control x_ctl;
} t_lpreson_tilde;
t_int *lpreson_tilde_perform(t_int *w)
{
t_object x_obj;
t_lpreson_tilde *x = (t_lpreson_tilde *)(w[1]);
t_lpreson_control *ctl = (t_lpreson_control *)(w[2]);
int n = (int)(w[3]);
t_float *in = ctl->c_residual;
t_float *out = ctl->c_output;
t_int ord = x->x_order;
float mem[ord+1];
/*
* Do the inverse filtering
*
* 'data_in' : residual signal (length 'len')
* 'data_out' : output frame (length 'len')
* 'coeff' : the parcor coefficients (length 'tap')
* 'lattice_iir' : filter memory - Previously initialised using init_lattice_iir_filter()
*
*/
int k, i;
float sri;
for (i=0;i<=ord;i++)
{
// SETFLOAT (&schur->x_parcors[i],0);
mem[i] = 0.0;
}
for (k = 0; k < n; k++ )
{
/* Synthesis filter - Lattice structure */
sri = in[k];
for (i=0; i<ord; i++)
{
t_float parcor = atom_getfloatarg ((ord-1-i),ord,ctl->x_parcors);
sri = sri - parcor * mem[ord-1-i];
mem[ord-i] = mem[ord-1-i] + parcor*sri;
}
out[k] = sri;
mem[0] = sri;
} /* next k */
return(w+4);
}
static void lpreson_tilde_list(t_lpreson_tilde *x, t_symbol *s, int argc, t_atom *argv)
{
if (argc)
{
// x->x_ctl.parc_interp_two = copybytes(x->x_ctl.parc_interp_one, x->x_ctl.parc_ord_one * sizeof(t_atom));
// x->x_ctl.parc_ord_two = x->x_ctl.parc_ord_one;
// x->x_ctl.parc_interp_one = copybytes(x->x_ctl.parcors, x->x_order * sizeof(t_atom));
// x->x_ctl.parc_ord_one = x->x_order;
freebytes(x->x_ctl.x_parcors, x->x_order * sizeof(t_atom));
}
x->x_ctl.x_parcors = copybytes(argv, argc * sizeof(t_atom));
x->x_order = argc;
}
void *lpreson_tilde_dsp(t_lpreson_tilde *x, t_signal **sp)
{
x->x_ctl.c_residual = sp[0]->s_vec;
x->x_ctl.c_output = sp[1]->s_vec;
dsp_add(lpreson_tilde_perform, 3, x, &x->x_ctl, sp[0]->s_n);
return (void *)x;
}
void *lpreson_tilde_new(t_floatarg f)
{
t_lpreson_tilde *x = (t_lpreson_tilde *)pd_new(lpreson_tilde_class);
x->x_order = f >= 1 ? (int)f : 5;
outlet_new(&x->x_obj, &s_signal);
return (void *)x;
}
void lpreson_tilde_setup(void)
{
lpreson_tilde_class = class_new(gensym("lpreson~"), (t_newmethod)lpreson_tilde_new, 0, sizeof(t_lpreson_tilde), CLASS_DEFAULT, A_DEFFLOAT, 0);
post(". . Lattice IIR filter for lpc. . . . . . .");
post(". . by Nicolas Chetry <okin@altern.org> . .");
post(". & Edward Kelly <morph_2016@yahoo.co.uk> .");
class_addmethod(lpreson_tilde_class, (t_method)lpreson_tilde_dsp, gensym("dsp"), 0);
class_addlist(lpreson_tilde_class, lpreson_tilde_list);
CLASS_MAINSIGNALIN(lpreson_tilde_class, t_lpreson_tilde, f_dummy);
}
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