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diff --git a/intern/audaspace/FX/AUD_BaseIIRFilterReader.h b/intern/audaspace/FX/AUD_BaseIIRFilterReader.h
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+/*
+ * $Id$
+ *
+ * ***** BEGIN LGPL LICENSE BLOCK *****
+ *
+ * Copyright 2009 Jörg Hermann Müller
+ *
+ * This file is part of AudaSpace.
+ *
+ * AudaSpace is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * AudaSpace 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with AudaSpace.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * ***** END LGPL LICENSE BLOCK *****
+ */
+
+#ifndef AUD_BASEIIRFILTERREADER
+#define AUD_BASEIIRFILTERREADER
+
+#include "AUD_EffectReader.h"
+#include "AUD_Buffer.h"
+
+/**
+ * This class is a base class for infinite impulse response filters.
+ */
+class AUD_BaseIIRFilterReader : public AUD_EffectReader
+{
+private:
+	/**
+	 * Channel count.
+	 */
+	const int m_channels;
+
+	/**
+	 * Length of input samples needed.
+	 */
+	const int m_xlen;
+
+	/**
+	 * Length of output samples needed.
+	 */
+	const int m_ylen;
+
+	/**
+	 * The playback buffer.
+	 */
+	AUD_Buffer m_buffer;
+
+	/**
+	 * The last in samples array.
+	 */
+	sample_t* m_x;
+
+	/**
+	 * The last out samples array.
+	 */
+	sample_t* m_y;
+
+	/**
+	 * Position of the current input sample in the input array.
+	 */
+	int m_xpos;
+
+	/**
+	 * Position of the current output sample in the output array.
+	 */
+	int m_ypos;
+
+	/**
+	 * Current channel.
+	 */
+	int m_channel;
+
+	// hide copy constructor and operator=
+	AUD_BaseIIRFilterReader(const AUD_BaseIIRFilterReader&);
+	AUD_BaseIIRFilterReader& operator=(const AUD_BaseIIRFilterReader&);
+
+protected:
+	/**
+	 * Creates a new base IIR filter reader.
+	 * \param reader The reader to read from.
+	 * \param in The count of past input samples needed.
+	 * \param out The count of past output samples needed.
+	 */
+	AUD_BaseIIRFilterReader(AUD_IReader* reader, int in, int out);
+
+public:
+	inline sample_t x(int pos)
+	{
+		return m_x[(m_xpos + pos + m_xlen) % m_xlen * m_channels + m_channel];
+	}
+
+	inline sample_t y(int pos)
+	{
+		return m_y[(m_ypos + pos + m_ylen) % m_ylen * m_channels + m_channel];
+	}
+
+	virtual ~AUD_BaseIIRFilterReader();
+
+	virtual void read(int & length, sample_t* & buffer);
+
+	virtual sample_t filter()=0;
+};
+
+#endif //AUD_BASEIIRFILTERREADER