1 files changed, 61 insertions, 0 deletions
diff --git a/gr-digital/lib/digital_diff_decoder_bb.cc b/gr-digital/lib/digital_diff_decoder_bb.cc
new file mode 100644
index 000000000..7b8e8726a
--- /dev/null
+++ b/gr-digital/lib/digital_diff_decoder_bb.cc
@@ -0,0 +1,61 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2006,2010,2012 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <digital_diff_decoder_bb.h>
+#include <gr_io_signature.h>
+
+digital_diff_decoder_bb_sptr
+digital_make_diff_decoder_bb (unsigned int modulus)
+{
+  return gnuradio::get_initial_sptr(new digital_diff_decoder_bb(modulus));
+}
+
+digital_diff_decoder_bb::digital_diff_decoder_bb (unsigned int modulus)
+  : gr_sync_block ("diff_decoder_bb",
+		   gr_make_io_signature (1, 1, sizeof (unsigned char)),
+		   gr_make_io_signature (1, 1, sizeof (unsigned char))),
+    d_modulus(modulus)
+{
+  set_history(2);	// need to look at two inputs
+}
+
+int
+digital_diff_decoder_bb::work (int noutput_items,
+			       gr_vector_const_void_star &input_items,
+			       gr_vector_void_star &output_items)
+{
+  const unsigned char *in = (const unsigned char *) input_items[0];
+  unsigned char *out = (unsigned char *) output_items[0];
+  in += 1;	// ensure that in[-1] is valid
+
+  unsigned modulus = d_modulus;
+
+  for (int i = 0; i < noutput_items; i++) {
+    out[i] = (in[i] - in[i-1]) % modulus;
+  }
+
+  return noutput_items;
+}