1 files changed, 71 insertions, 0 deletions
diff --git a/gr-digital/lib/diff_decoder_bb_impl.cc b/gr-digital/lib/diff_decoder_bb_impl.cc
new file mode 100644
index 0000000000..74c247a830
--- /dev/null
+++ b/gr-digital/lib/diff_decoder_bb_impl.cc
@@ -0,0 +1,71 @@
+/* -*- 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 "diff_decoder_bb_impl.h"
+#include <gr_io_signature.h>
+
+namespace gr {
+  namespace digital {
+    diff_decoder_bb::sptr
+    diff_decoder_bb::make(unsigned int modulus)
+    {
+      return gnuradio::get_initial_sptr
+	(new diff_decoder_bb_impl(modulus));
+    }
+
+    diff_decoder_bb_impl::diff_decoder_bb_impl(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
+    }
+
+    diff_decoder_bb_impl::~diff_decoder_bb_impl()
+    {
+    }
+
+    int
+    diff_decoder_bb_impl::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;
+    }
+
+  } /* namespace digital */
+} /* namespace gr */