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-rw-r--r--src/iemlib1/biquad_freq_resp.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/src/iemlib1/biquad_freq_resp.c b/src/iemlib1/biquad_freq_resp.c
new file mode 100644
index 0000000..3ebe25d
--- /dev/null
+++ b/src/iemlib1/biquad_freq_resp.c
@@ -0,0 +1,92 @@
+/* For information on usage and redistribution, and for a DISCLAIMER OF ALL
+* WARRANTIES, see the file, "LICENSE.txt," in this distribution.
+
+iemlib1 written by Thomas Musil, Copyright (c) IEM KUG Graz Austria 2000 - 2003 */
+
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+
+
+#include "m_pd.h"
+#include "iemlib.h"
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+
+/* --------------------------- biquad_freq_resp ----------------------------- */
+
+typedef struct _biquad_freq_resp
+{
+ t_object x_obj;
+ float a0;
+ float a1;
+ float a2;
+ float b1;
+ float b2;
+ t_outlet *x_out_re;
+ t_outlet *x_out_im;
+} t_biquad_freq_resp;
+
+static t_class *biquad_freq_resp_class;
+
+static void biquad_freq_resp_float(t_biquad_freq_resp *x, t_float f)
+{
+ float re1, im1, re2, im2;
+ float c, s, a;
+
+ if(f < 0.0f)
+ f = 0.0f;
+ else if(f > 180.0f)
+ f = 180.0;
+ f *= 3.14159265f;
+ f /= 180.0f;
+
+ c = cos(f);
+ s = sin(f);
+
+ re1 = x->a0 + x->a1*c + x->a2*(c*c - s*s);
+ im1 = x->a1*s + x->a2*2.0f*(s*c);
+ re2 = 1.0f - x->b1*c - x->b2*(c*c - s*s);
+ im2 = -x->b1*s - x->b2*2.0f*(s*c);
+ a = re2*re2 + im2*im2;
+ outlet_float(x->x_out_im, (re1*im2 - re2*im1)/a);/* because z^-1 = e^-jwt, negative sign */
+ outlet_float(x->x_out_re, (re1*re2 + im1*im2)/a);
+
+}
+/* y/x = (a0 + a1*z-1 + a2*z-2)/(1 - b1*z-1 - b2*z-2);*/
+
+static void biquad_freq_resp_list(t_biquad_freq_resp *x, t_symbol *s, int argc, t_atom *argv)
+{
+ if((argc == 5)&&IS_A_FLOAT(argv,4)&&IS_A_FLOAT(argv,3)&&IS_A_FLOAT(argv,2)&&IS_A_FLOAT(argv,1)&&IS_A_FLOAT(argv,0))
+ {
+ x->b1 = (float)atom_getfloatarg(0, argc, argv);
+ x->b2 = (float)atom_getfloatarg(1, argc, argv);
+ x->a0 = (float)atom_getfloatarg(2, argc, argv);
+ x->a1 = (float)atom_getfloatarg(3, argc, argv);
+ x->a2 = (float)atom_getfloatarg(4, argc, argv);
+ }
+}
+
+static void *biquad_freq_resp_new(void)
+{
+ t_biquad_freq_resp *x = (t_biquad_freq_resp *)pd_new(biquad_freq_resp_class);
+ x->x_out_re = outlet_new(&x->x_obj, &s_float);
+ x->x_out_im = outlet_new(&x->x_obj, &s_float);
+ x->b1 = 0.0f;
+ x->b2 = 0.0f;
+ x->a0 = 0.0f;
+ x->a1 = 0.0f;
+ x->a2 = 0.0f;
+ return (x);
+}
+
+void biquad_freq_resp_setup(void)
+{
+ biquad_freq_resp_class = class_new(gensym("biquad_freq_resp"), (t_newmethod)biquad_freq_resp_new, 0,
+ sizeof(t_biquad_freq_resp), 0, 0);
+ class_addfloat(biquad_freq_resp_class, biquad_freq_resp_float);
+ class_addlist(biquad_freq_resp_class, (t_method)biquad_freq_resp_list);
+ class_sethelpsymbol(biquad_freq_resp_class, gensym("iemhelp/help-biquad_freq_resp"));
+} \ No newline at end of file