1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
#include "../src/m_pd.h"
#include "../src/m_fixed.h"
typedef struct biquadctl
{
t_sample c_x1;
t_sample c_x2;
t_sample c_fb1;
t_sample c_fb2;
t_sample c_ff1;
t_sample c_ff2;
t_sample c_ff3;
} t_biquadctl;
typedef struct sigbiquad
{
t_object x_obj;
float x_f;
t_biquadctl x_cspace;
t_biquadctl *x_ctl;
} t_sigbiquad;
t_class *sigbiquad_class;
static void sigbiquad_list(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv);
static void *sigbiquad_new(t_symbol *s, int argc, t_atom *argv)
{
t_sigbiquad *x = (t_sigbiquad *)pd_new(sigbiquad_class);
outlet_new(&x->x_obj, gensym("signal"));
x->x_ctl = &x->x_cspace;
x->x_cspace.c_x1 = x->x_cspace.c_x2 = 0;
sigbiquad_list(x, s, argc, argv);
x->x_f = 0;
return (x);
}
static t_int *sigbiquad_perform(t_int *w)
{
t_sample *in = (t_sample *)(w[1]);
t_sample *out = (t_sample *)(w[2]);
t_biquadctl *c = (t_biquadctl *)(w[3]);
int n = (t_int)(w[4]);
int i;
t_sample last = c->c_x1;
t_sample prev = c->c_x2;
t_sample fb1 = c->c_fb1;
t_sample fb2 = c->c_fb2;
t_sample ff1 = c->c_ff1;
t_sample ff2 = c->c_ff2;
t_sample ff3 = c->c_ff3;
for (i = 0; i < n; i++)
{
t_sample output = *in++ + mult(fb1,last) + mult(fb2,prev);
if (PD_BADFLOAT(output))
output = 0;
*out++ = mult(ff1,output) + mult(ff2,last) + mult(ff3,prev);
prev = last;
last = output;
}
c->c_x1 = last;
c->c_x2 = prev;
return (w+5);
}
static void sigbiquad_list(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv)
{
#ifdef ROCKBOX
(void) s;
#endif
float fb1 = atom_getfloatarg(0, argc, argv);
float fb2 = atom_getfloatarg(1, argc, argv);
float ff1 = atom_getfloatarg(2, argc, argv);
float ff2 = atom_getfloatarg(3, argc, argv);
float ff3 = atom_getfloatarg(4, argc, argv);
float discriminant = fb1 * fb1 + 4 * fb2;
t_biquadctl *c = x->x_ctl;
if (discriminant < 0) /* imaginary roots -- resonant filter */
{
/* they're conjugates so we just check that the product
is less than one */
if (fb2 >= -1.0f) goto stable;
}
else /* real roots */
{
/* check that the parabola 1 - fb1 x - fb2 x^2 has a
vertex between -1 and 1, and that it's nonnegative
at both ends, which implies both roots are in [1-,1]. */
if (fb1 <= 2.0f && fb1 >= -2.0f &&
1.0f - fb1 -fb2 >= 0 && 1.0f + fb1 - fb2 >= 0)
goto stable;
}
/* if unstable, just bash to zero */
fb1 = fb2 = ff1 = ff2 = ff3 = 0;
stable:
c->c_fb1 = ftofix(fb1);
c->c_fb2 = ftofix(fb2);
c->c_ff1 = ftofix(ff1);
c->c_ff2 = ftofix(ff2);
c->c_ff3 = ftofix(ff3);
}
static void sigbiquad_set(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv)
{
#ifdef ROCKBOX
(void) s;
#endif
t_biquadctl *c = x->x_ctl;
c->c_x1 = atom_getfloatarg(0, argc, argv);
c->c_x2 = atom_getfloatarg(1, argc, argv);
}
static void sigbiquad_dsp(t_sigbiquad *x, t_signal **sp)
{
dsp_add(sigbiquad_perform, 4,
sp[0]->s_vec, sp[1]->s_vec,
x->x_ctl, sp[0]->s_n);
}
void biquad_tilde_setup(void)
{
sigbiquad_class = class_new(gensym("biquad~"), (t_newmethod)sigbiquad_new,
0, sizeof(t_sigbiquad), 0, A_GIMME, 0);
CLASS_MAINSIGNALIN(sigbiquad_class, t_sigbiquad, x_f);
class_addmethod(sigbiquad_class, (t_method)sigbiquad_dsp, gensym("dsp"), 0);
class_addlist(sigbiquad_class, sigbiquad_list);
class_addmethod(sigbiquad_class, (t_method)sigbiquad_set, gensym("set"),
A_GIMME, 0);
class_addmethod(sigbiquad_class, (t_method)sigbiquad_set, gensym("clear"),
A_GIMME, 0);
}
|
