summaryrefslogtreecommitdiffstats
path: root/apps/plugins/pdbox/PDa/extra/lowshelf.c
blob: 52c30d839dd06de5e9df6cae8de039ea057fa450 (plain)
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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
/* (C) Guenter Geiger <geiger@epy.co.at> */


/*

 These filter coefficients computations are taken from
 http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  

 written by Robert Bristow-Johnson

*/

#include "m_pd.h"
#ifdef NT
#pragma warning( disable : 4244 )
#pragma warning( disable : 4305 )
#endif
#include <math.h>
#include "filters.h"



/* ------------------- lowshelf ----------------------------*/

static t_class *lowshelf_class;

void lowshelf_bang(t_rbjfilter *x)
{
     t_atom at[5];
     t_float omega = e_omega(x->x_freq,x->x_rate);
     t_float A = e_A(x->x_gain);
     t_float cs = cos(omega);
     t_float sn = sin(omega);
     t_float beta = e_beta(A,x->x_bw*0.01);

     t_float b0 =    A*((A+1) - (A-1)*cs + beta*sn);
     t_float b1 = 2.*A*((A-1) - (A+1)*cs);
     t_float b2 =    A*((A+1) - (A-1)*cs - beta*sn);
     t_float a0 =      ((A+1) + (A-1)*cs + beta*sn);
     t_float a1 =  -2.*((A-1) + (A+1)*cs);
     t_float a2 =      ((A+1) + (A-1)*cs - beta*sn);

/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
     
     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
       post("lowshelf: filter unstable -> resetting");
       a0=1.;a1=0.;a2=0.;
       b0=1.;b1=0.;b2=0.;
     }

     SETFLOAT(at,-a1/a0);
     SETFLOAT(at+1,-a2/a0);
     SETFLOAT(at+2,b0/a0);
     SETFLOAT(at+3,b1/a0);
     SETFLOAT(at+4,b2/a0);
     
     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
}


void lowshelf_float(t_rbjfilter *x,t_floatarg f)
{
     x->x_freq = f;
     lowshelf_bang(x);
}


static void *lowshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
{
    t_rbjfilter *x = (t_rbjfilter *)pd_new(lowshelf_class);

    x->x_rate = 44100.0;
    outlet_new(&x->x_obj,&s_float);
    floatinlet_new(&x->x_obj, &x->x_gain);    
    floatinlet_new(&x->x_obj, &x->x_bw);
    if (f > 0.) x->x_freq = f;
    if (bw > 0.) x->x_bw = bw;
    if (g != 0.) x->x_gain = g;
    return (x);
}


void lowshelf_setup(void)
{
    lowshelf_class = class_new(gensym("lowshelf"), (t_newmethod)lowshelf_new, 0,
				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
    class_addbang(lowshelf_class,lowshelf_bang);
    class_addfloat(lowshelf_class,lowshelf_float);
}


/* (C) Guenter Geiger <geiger@epy.co.at> */


/*

 These filter coefficients computations are taken from
 http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  

 written by Robert Bristow-Johnson

*/

#include "m_pd.h"
#ifdef NT
#pragma warning( disable : 4244 )
#pragma warning( disable : 4305 )
#endif
#include <math.h>
#include "filters.h"



/* ------------------- lowshelf ----------------------------*/

static t_class *lowshelf_class;

void lowshelf_bang(t_rbjfilter *x)
{
     t_atom at[5];
     t_float omega = e_omega(x->x_freq,x->x_rate);
     t_float A = e_A(x->x_gain);
     t_float cs = cos(omega);
     t_float sn = sin(omega);
     t_float beta = e_beta(A,x->x_bw*0.01);

     t_float b0 =    A*((A+1) - (A-1)*cs + beta*sn);
     t_float b1 = 2.*A*((A-1) - (A+1)*cs);
     t_float b2 =    A*((A+1) - (A-1)*cs - beta*sn);
     t_float a0 =      ((A+1) + (A-1)*cs + beta*sn);
     t_float a1 =  -2.*((A-1) + (A+1)*cs);
     t_float a2 =      ((A+1) + (A-1)*cs - beta*sn);

/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
     
     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
       post("lowshelf: filter unstable -> resetting");
       a0=1.;a1=0.;a2=0.;
       b0=1.;b1=0.;b2=0.;
     }

     SETFLOAT(at,-a1/a0);
     SETFLOAT(at+1,-a2/a0);
     SETFLOAT(at+2,b0/a0);
     SETFLOAT(at+3,b1/a0);
     SETFLOAT(at+4,b2/a0);
     
     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
}


void lowshelf_float(t_rbjfilter *x,t_floatarg f)
{
     x->x_freq = f;
     lowshelf_bang(x);
}


static void *lowshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
{
    t_rbjfilter *x = (t_rbjfilter *)pd_new(lowshelf_class);

    x->x_rate = 44100.0;
    outlet_new(&x->x_obj,&s_float);
    floatinlet_new(&x->x_obj, &x->x_gain);    
    floatinlet_new(&x->x_obj, &x->x_bw);
    if (f > 0.) x->x_freq = f;
    if (bw > 0.) x->x_bw = bw;
    if (g != 0.) x->x_gain = g;
    return (x);
}


void lowshelf_setup(void)
{
    lowshelf_class = class_new(gensym("lowshelf"), (t_newmethod)lowshelf_new, 0,
				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
    class_addbang(lowshelf_class,lowshelf_bang);
    class_addfloat(lowshelf_class,lowshelf_float);
}