From 179bf7c56f7a8e4df6031d3366548f7afbee31d2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?IOhannes=20m=20zm=C3=B6lnig?=
 <zmoelnig@users.sourceforge.net>
Date: Tue, 31 Jan 2006 10:44:35 +0000
Subject: added the missing examples files; added a LICENSE (all the C-files
 are under pd's FreeBSD-like license, the HOWTO itself is
 CreativeCommons-ShareAlike 2.5)

svn path=/trunk/; revision=4525
---
 doc/tutorials/externals-howto/example4/pan~.c | 146 ++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 doc/tutorials/externals-howto/example4/pan~.c

(limited to 'doc/tutorials/externals-howto/example4/pan~.c')

diff --git a/doc/tutorials/externals-howto/example4/pan~.c b/doc/tutorials/externals-howto/example4/pan~.c
new file mode 100644
index 00000000..06dccd69
--- /dev/null
+++ b/doc/tutorials/externals-howto/example4/pan~.c
@@ -0,0 +1,146 @@
+/*
+ * HOWTO write an External for Pure data
+ * (c) 2001-2006 IOhannes m zmölnig zmoelnig[AT]iem.at
+ *
+ * this is the source-code for the fourth example in the HOWTO
+ * it creates a simple dsp-object:
+ * 2 input signals are mixed into 1 output signal
+ * the mixing-factor can be set via the 3rd inlet
+ *
+ * for legal issues please see the file LICENSE.txt
+ */
+
+
+/**
+ * include the interface to Pd 
+ */
+#include "m_pd.h"
+
+
+/**
+ * define a new "class" 
+ */
+static t_class *pan_tilde_class;
+
+
+/**
+ * this is the dataspace of our new object
+ * the first element is the mandatory "t_object"
+ * f_pan denotes the mixing-factor
+ * "f" is a dummy and is used to be able to send floats AS signals.
+ */
+typedef struct _pan_tilde {
+  t_object  x_obj;
+  t_sample f_pan;
+  t_sample f;
+} t_pan_tilde;
+
+
+/**
+ * this is the core of the object
+ * this perform-routine is called for each signal block
+ * the name of this function is arbitrary and is registered to Pd in the 
+ * pan_tilde_dsp() function, each time the DSP is turned on
+ *
+ * the argument to this function is just a pointer within an array
+ * we have to know for ourselves how many elements inthis array are
+ * reserved for us (hint: we declare the number of used elements in the
+ * pan_tilde_dsp() at registration
+ *
+ * since all elements are of type "t_int" we have to cast them to whatever
+ * we think is apropriate; "apropriate" is how we registered this function
+ * in pan_tilde_dsp()
+ */
+t_int *pan_tilde_perform(t_int *w)
+{
+  /* the first element is a pointer to the dataspace of this object */
+  t_pan_tilde *x = (t_pan_tilde *)(w[1]);
+  /* here is a pointer to the t_sample arrays that hold the 2 input signals */
+  t_sample  *in1 =    (t_sample *)(w[2]);
+  t_sample  *in2 =    (t_sample *)(w[3]);
+  /* here comes the signalblock that will hold the output signal */
+  t_sample  *out =    (t_sample *)(w[4]);
+  /* all signalblocks are of the same length */
+  int          n =           (int)(w[5]);
+  /* get (and clip) the mixing-factor */
+  t_sample f_pan = (x->f_pan<0)?0.0:(x->f_pan>1)?1.0:x->f_pan;
+  /* just a counter */
+  int i;
+
+  /* this is the main routine: 
+   * mix the 2 input signals into the output signal
+   */
+  for(i=0; i<n; i++)
+    {
+      out[i]=in1[i]*(1-f_pan)+in2[i]*f_pan;
+    }
+
+  /* return a pointer to the dataspace for the next dsp-object */
+  return (w+6);
+}
+
+
+/**
+ * register a special perform-routine at the dsp-engine
+ * this function gets called whenever the DSP is turned ON
+ * the name of this function is registered in pan_tilde_setup()
+ */
+void pan_tilde_dsp(t_pan_tilde *x, t_signal **sp)
+{
+  /* add pan_tilde_perform() to the DSP-tree;
+   * the pan_tilde_perform() will expect "5" arguments (packed into an
+   * t_int-array), which are:
+   * the objects data-space, 3 signal vectors (which happen to be
+   * 2 input signals and 1 output signal) and the length of the
+   * signal vectors (all vectors are of the same length)
+   */
+  dsp_add(pan_tilde_perform, 5, x,
+          sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, sp[0]->s_n);
+}
+
+
+/**
+ * this is the "constructor" of the class
+ * the argument is the initial mixing-factir
+ */
+void *pan_tilde_new(t_floatarg f)
+{
+  t_pan_tilde *x = (t_pan_tilde *)pd_new(pan_tilde_class);
+
+  /* save the mixing factor in our dataspace */
+  x->f_pan = f;
+  
+  /* create a new signal-inlet */
+  inlet_new(&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
+
+  /* create a new passive inlet for the mixing-factor */
+  floatinlet_new (&x->x_obj, &x->f_pan);
+
+  /* create a new signal-outlet */
+  outlet_new(&x->x_obj, &s_signal);
+
+  return (void *)x;
+}
+
+
+/**
+ * define the function-space of the class
+ * within a single-object external the name of this function is very special
+ */
+void pan_tilde_setup(void) {
+  pan_tilde_class = class_new(gensym("pan~"),
+        (t_newmethod)pan_tilde_new,
+        0, sizeof(t_pan_tilde),
+        CLASS_DEFAULT, 
+        A_DEFFLOAT, 0);
+
+  /* whenever the audio-engine is turned on, the "pan_tilde_dsp()" 
+   * function will get called
+   */
+  class_addmethod(pan_tilde_class,
+        (t_method)pan_tilde_dsp, gensym("dsp"), 0);
+  /* if no signal is connected to the first inlet, we can as well 
+   * connect a number box to it and use it as "signal"
+   */
+  CLASS_MAINSIGNALIN(pan_tilde_class, t_pan_tilde, f);
+}
-- 
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