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diff --git a/gr-howto-write-a-block/include/howto_square2_ff.h b/gr-howto-write-a-block/include/howto_square2_ff.h
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+/* -*- c++ -*- */
+/*
+ * Copyright 2004 Free Software Foundation, Inc.
+ * 
+ * This file is part of GNU Radio
+ * 
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ * 
+ * GNU Radio 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 General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+#ifndef INCLUDED_HOWTO_SQUARE2_FF_H
+#define INCLUDED_HOWTO_SQUARE2_FF_H
+
+#include <howto_api.h>
+#include <gr_sync_block.h>
+
+class howto_square2_ff;
+
+/*
+ * We use boost::shared_ptr's instead of raw pointers for all access
+ * to gr_blocks (and many other data structures).  The shared_ptr gets
+ * us transparent reference counting, which greatly simplifies storage
+ * management issues.  This is especially helpful in our hybrid
+ * C++ / Python system.
+ *
+ * See http://www.boost.org/libs/smart_ptr/smart_ptr.htm
+ *
+ * As a convention, the _sptr suffix indicates a boost::shared_ptr
+ */
+typedef boost::shared_ptr<howto_square2_ff> howto_square2_ff_sptr;
+
+/*!
+ * \brief Return a shared_ptr to a new instance of howto_square2_ff.
+ *
+ * To avoid accidental use of raw pointers, howto_square2_ff's
+ * constructor is private.  howto_make_square2_ff is the public
+ * interface for creating new instances.
+ */
+HOWTO_API howto_square2_ff_sptr howto_make_square2_ff ();
+
+/*!
+ * \brief square2 a stream of floats.
+ * \ingroup block
+ *
+ * This uses the preferred technique: subclassing gr_sync_block.
+ */
+class HOWTO_API howto_square2_ff : public gr_sync_block
+{
+private:
+  // The friend declaration allows howto_make_square2_ff to
+  // access the private constructor.
+
+  friend HOWTO_API howto_square2_ff_sptr howto_make_square2_ff ();
+
+  howto_square2_ff ();  	// private constructor
+
+ public:
+  ~howto_square2_ff ();	// public destructor
+
+  // Where all the action really happens
+
+  int work (int noutput_items,
+	    gr_vector_const_void_star &input_items,
+	    gr_vector_void_star &output_items);
+};
+
+#endif /* INCLUDED_HOWTO_SQUARE2_FF_H */