1 files changed, 62 insertions, 0 deletions
diff --git a/gr-atsc/src/lib/atsci_basic_trellis_encoder.cc b/gr-atsc/src/lib/atsci_basic_trellis_encoder.cc
new file mode 100644
index 000000000..35081eb8e
--- /dev/null
+++ b/gr-atsc/src/lib/atsci_basic_trellis_encoder.cc
@@ -0,0 +1,62 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2002 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 2, 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <atsci_basic_trellis_encoder.h>
+#include <assert.h>
+
+const unsigned char atsci_basic_trellis_encoder::next_state[32] = {
+  0,1,4,5,
+  2,3,6,7,
+  1,0,5,4,
+  3,2,7,6,
+  4,5,0,1,
+  6,7,2,3,
+  5,4,1,0,
+  7,6,3,2
+};
+
+const unsigned char atsci_basic_trellis_encoder::out_symbol[32] = {
+  0,2,4,6,
+  1,3,5,7,
+  0,2,4,6,
+  1,3,5,7,
+  4,6,0,2,
+  5,7,1,3,
+  4,6,0,2,
+  5,7,1,3
+};
+
+
+/*!
+ * Encode two bit INPUT into 3 bit return value.  Domain is [0,3],
+ * Range is [0,7].  The mapping to bipolar levels is not done.
+ */
+
+int
+atsci_basic_trellis_encoder::encode (unsigned int input)
+{
+  assert (input < 4);
+  int index = (state << 2) + input; 
+  state = next_state[index];
+  return out_symbol[index];
+}
+