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/*
* ffpoly.c - compute a finite field polynomial
* Copyright (c) by Tom Schouten <pdp@zzz.kotnet.org>
*
* 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 <stdlib.h>
typedef struct ffpoly_struct
{
t_object x_obj;
t_float x_f;
t_outlet *x_outlet;
t_int *x_coef;
t_int x_poly_order;
t_int x_field_order;
t_int x_lastpackedcoef;
} t_ffpoly;
static void ffpoly_compute(t_ffpoly *x, t_floatarg fcoef)
{
int in = (int)fcoef;
int fo = x->x_field_order;
int po = x->x_poly_order;
t_int* c = x->x_coef;
int i, out;
in %= fo;
if (in < 0) in += fo;
out = c[po];
for (i=po-1; i>=0; i--){
out *= in;
out += c[i];
out %= fo;
}
outlet_float(x->x_outlet, (float)out);
}
/* this sets all coefficients given one float */
static void ffpoly_coefficients(t_ffpoly *x, t_floatarg fcoef)
{
int coef = (int)fcoef;
int i;
if (coef < 0) coef = -coef;
x->x_lastpackedcoef = coef;
for (i=0; i<x->x_poly_order + 1; i++){
x->x_coef[i] = coef % x->x_field_order;
coef = coef / x->x_field_order;
}
}
/* this sets one coefficient */
static void ffpoly_coef(t_ffpoly *x, t_floatarg index, t_floatarg val)
{
int i = (int)index;
int v = (int)val;
if (i<0) return;
if (i>x->x_poly_order) return;
v %= x->x_field_order;
if (v<0) v += x->x_field_order;
x->x_coef[i] = v;
}
static void ffpoly_fieldorder(t_ffpoly *x, t_floatarg ffieldorder)
{
int i;
int order = (int)ffieldorder;
if (order < 2) order = 2;
x->x_field_order = order;
for (i=0; i<x->x_poly_order+1; i++)
x->x_coef[i] %= x->x_field_order;
//ffpoly_coefficients(x, x->x_lastpackedcoef);
}
static void ffpoly_free(t_ffpoly *x)
{
free (x->x_coef);
}
t_class *ffpoly_class;
static void *ffpoly_new(t_floatarg fpolyorder, t_floatarg ffieldorder)
{
t_int polyorder = (int)fpolyorder;
t_int fieldorder = (int)ffieldorder;
t_ffpoly *x = (t_ffpoly *)pd_new(ffpoly_class);
if (polyorder < 1) polyorder = 1;
if (fieldorder < 2) fieldorder = 2;
x->x_poly_order = polyorder;
x->x_field_order = fieldorder;
x->x_coef = (t_int *)malloc((x->x_poly_order + 1) * sizeof(int));
/* set poly to f(x) = x */
ffpoly_coefficients(x, x->x_field_order);
x->x_outlet = outlet_new(&x->x_obj, &s_float);
return (void *)x;
}
#ifdef __cplusplus
extern "C"
{
#endif
void ffpoly_setup(void)
{
ffpoly_class = class_new(gensym("ffpoly"), (t_newmethod)ffpoly_new,
(t_method)ffpoly_free, sizeof(t_ffpoly), 0, A_DEFFLOAT, A_DEFFLOAT, A_NULL);
class_addmethod(ffpoly_class, (t_method)ffpoly_coefficients, gensym("coefficients"), A_FLOAT, A_NULL);
class_addmethod(ffpoly_class, (t_method)ffpoly_coef, gensym("coef"), A_FLOAT, A_FLOAT, A_NULL);
class_addmethod(ffpoly_class, (t_method)ffpoly_fieldorder, gensym("order"), A_FLOAT, A_NULL);
class_addfloat(ffpoly_class, (t_method)ffpoly_compute);
}
#ifdef __cplusplus
}
#endif
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