1 files changed, 47 insertions, 0 deletions
diff --git a/gr-howto-write-a-block/python/square3_ff.py b/gr-howto-write-a-block/python/square3_ff.py
new file mode 100644
index 000000000..df702734e
--- /dev/null
+++ b/gr-howto-write-a-block/python/square3_ff.py
@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+#
+# Copyright 2013 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.
+#
+
+import numpy
+from gnuradio import gr
+
+class square3_ff(gr.sync_block):
+    " Squaring block "
+    def __init__(self):
+        gr.sync_block.__init__(
+            self,
+            name = "square3_ff",
+            in_sig = [numpy.float32], # Input signature: 1 float at a time
+            out_sig = [numpy.float32], # Output signature: 1 float at a time
+        )
+
+    def work(self, input_items, output_items):
+        """ Notes:
+        - You must not forget the [:] at the output items, otherwise
+          stuff doesn't truly get copied to the output
+        - Both input_ and output_items[N] are numpy arrays, so you can
+          do fancy stuff like multiplying them elementwise
+        - noutput_items and ninput_items are implicit in the length of
+          output_items and input_items, respectively
+        """
+        output_items[0][:] = input_items[0] * input_items[0]
+        return len(output_items[0])
+