An external that emulates an RC timer, similar to lop~ but good for envelope generation.

svn path=/trunk/externals/mrpeach/; revision=13207

1 files changed, 68 insertions, 0 deletions

diff --git a/rc~/rc~.c b/rc~/rc~.c
new file mode 100644
index 0000000..87525b8
--- /dev/null
+++ b/rc~/rc~.c
@@ -0,0 +1,68 @@
+/* rc~.c by Martin Peach 20100315 */
+/* Pd external emulating a resistor-capacitor low-pass filter */
+/* The control parameter is a time constant in seconds (or resistance X capacitance) */
+
+#include "m_pd.h"
+
+static t_class *rc_tilde_class;
+
+typedef struct _rc_tilde
+{
+    t_object    rc_obj;
+    t_float     rc_rc;
+    t_float     rc_f;
+    t_sample    rc_node;
+} t_rc_tilde;
+
+t_int *rc_tilde_perform(t_int *w)
+{
+    t_rc_tilde      *x = (t_rc_tilde *)(w[1]);
+    t_sample        *in = (t_sample *)(w[2]);
+    t_sample        *out = (t_sample *)(w[3]);
+    int             n = (int)(w[4]);
+    float           slewrate;
+    float           sp = 1.0/sys_getsr();
+
+    if (x->rc_rc < sp) slewrate = 1.0;    
+    else slewrate = sp/x->rc_rc;
+        
+    while (n--)
+    {
+        x->rc_node += (*in++ - x->rc_node)*slewrate;
+        *out++ = x->rc_node;
+    }
+
+    return (w+5);
+}
+
+void rc_tilde_dsp(t_rc_tilde *x, t_signal **sp)
+{
+    dsp_add(rc_tilde_perform, 4, x, sp[0]->s_vec, sp[1]->s_vec, sp[0]->s_n);
+}
+
+void *rc_tilde_new(t_floatarg f)
+{
+    t_rc_tilde *x = (t_rc_tilde *)pd_new(rc_tilde_class);
+
+    x->rc_rc = f;
+    x->rc_node = 0.0;
+  
+    floatinlet_new (&x->rc_obj, &x->rc_rc);
+    outlet_new(&x->rc_obj, &s_signal);
+    return (void *)x;
+}
+
+void rc_tilde_setup(void)
+{
+    rc_tilde_class = class_new(gensym("rc~"),
+        (t_newmethod)rc_tilde_new,
+        0, sizeof(t_rc_tilde),
+        CLASS_DEFAULT, 
+        A_DEFFLOAT, 0);
+
+    class_addmethod(rc_tilde_class, (t_method)rc_tilde_dsp, gensym("dsp"), 0);
+    CLASS_MAINSIGNALIN(rc_tilde_class, t_rc_tilde, rc_f);
+}
+
+/* fin rc~.c */
+