1 files changed, 71 insertions, 0 deletions
diff --git a/arts/modules/synth/synth_shelve_cutoff_impl.cc b/arts/modules/synth/synth_shelve_cutoff_impl.cc
new file mode 100644
index 00000000..888480e3
--- /dev/null
+++ b/arts/modules/synth/synth_shelve_cutoff_impl.cc
@@ -0,0 +1,71 @@
+/*
+
+    Copyright (C) 2000 Stefan Westerfeld
+                       stefan@space.twc.de
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+  
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+   
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+    Boston, MA 02111-1307, USA.
+
+    */
+
+#include "artsmodulessynth.h"
+#include "stdsynthmodule.h"
+#include "c_filter_stuff.h"
+
+using namespace Arts;
+
+class Synth_SHELVE_CUTOFF_impl : virtual public Synth_SHELVE_CUTOFF_skel,
+								 virtual public StdSynthModule
+{
+protected:
+	filter f;
+public:
+	void streamInit();
+	void calculateBlock(unsigned long samples);
+};
+
+REGISTER_IMPLEMENTATION(Synth_SHELVE_CUTOFF_impl);
+
+void Synth_SHELVE_CUTOFF_impl::streamInit()
+{
+	initfilter(&f);
+}
+
+void Synth_SHELVE_CUTOFF_impl::calculateBlock(unsigned long samples)
+{
+	float filterfrequency = frequency[0];
+
+	// the shelve-lowpass-filter is extremely sensitive to frequencies which
+	// are out of it's range (it produces NaN's then) so we'll be careful ;)
+	if(filterfrequency > 22000.0) filterfrequency = 22000.0;
+	if(filterfrequency < 1.0) filterfrequency = 1.0;
+	setfilter_shelvelowpass(&f,filterfrequency,80.0);
+
+	unsigned long i;
+
+	for(i=0;i<samples;i++)
+	{
+		// better paste applyfilter here instead of:
+		// *outsig++ = 0.95 * applyfilter(&f,*insig++);
+  		f.x = invalue[i];
+  		f.y = f.cx * f.x + f.cx1 * f.x1 + f.cx2 * f.x2
+    		+ f.cy1 * f.y1 + f.cy2 * f.y2;
+  		f.x2 = f.x1;
+  		f.x1 = f.x;
+  		f.y2 = f.y1;
+  		f.y1 = f.y;
+  		outvalue[i] = 0.95 * f.y;
+	}
+}