From 5e3a338b129e9ce6b5369c829ccd7290ed53c7e7 Mon Sep 17 00:00:00 2001
From: Martin Peach <mrpeach@users.sourceforge.net>
Date: Mon, 15 Mar 2010 21:24:35 +0000
Subject: An external that emulates an RC timer, similar to lop~ but good for
 envelope generation.

svn path=/trunk/externals/mrpeach/; revision=13207
---
 rc~/rc~-help.pd | 27 +++++++++++++++++++++++
 rc~/rc~.c       | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)
 create mode 100644 rc~/rc~-help.pd
 create mode 100644 rc~/rc~.c

diff --git a/rc~/rc~-help.pd b/rc~/rc~-help.pd
new file mode 100644
index 0000000..3222b7e
--- /dev/null
+++ b/rc~/rc~-help.pd
@@ -0,0 +1,27 @@
+#N canvas 632 273 450 377 10;
+#X obj 52 180 dac~;
+#X obj 53 143 *~;
+#X obj 52 79 tgl 15 0 empty empty empty 17 7 0 10 -4034 -13381 -1 0
+1;
+#X obj 79 79 nbx 5 14 0 1e+37 0 1 empty empty seconds 60 8 0 10 -4034
+-13381 -13381 0.73 256;
+#X obj 52 57 metro 1000;
+#X obj 52 36 tgl 15 0 empty empty empty 17 7 0 10 -4034 -13381 -1 1
+1;
+#X obj 52 99 rc~ 1;
+#X text 191 167 Author: Martin Peach;
+#X text 191 186 2010/03/15;
+#X obj 67 121 noise~;
+#X obj 136 230 lop~;
+#X text 63 230 similar to:;
+#X text 49 -22 rc~ emulates a capacitor charging through a resistor.
+The creation argument can be overriden by the right inlet \, and represents
+a charging time constant in seconds.;
+#X connect 1 0 0 0;
+#X connect 1 0 0 1;
+#X connect 2 0 6 0;
+#X connect 3 0 6 1;
+#X connect 4 0 2 0;
+#X connect 5 0 4 0;
+#X connect 6 0 1 0;
+#X connect 9 0 1 1;
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 */
+
-- 
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