1 files changed, 69 insertions, 0 deletions
diff --git a/gr-blocks/include/blocks/lfsr_15_1_0.h b/gr-blocks/include/blocks/lfsr_15_1_0.h
new file mode 100644
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+++ b/gr-blocks/include/blocks/lfsr_15_1_0.h
@@ -0,0 +1,69 @@
+/* -*- 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_GRI_LFSR_15_1_0_H
+#define INCLUDED_GRI_LFSR_15_1_0_H
+
+#include <blocks/api.h>
+
+namespace gr {
+  namespace blocks {
+
+    /*!
+     * \brief Linear Feedback Shift Register using primitive polynomial x^15 + x + 1
+     * \ingroup misc
+     *
+     * Generates a maximal length pseudo-random sequence of length
+     * 2^15 - 1 bits.
+     */
+    class BLOCKS_API lfsr_15_1_0
+    {
+    private:
+      unsigned long d_sr;    // shift register
+
+    public:
+      lfsr_15_1_0() { reset(); }
+
+      void reset() { d_sr = 0x7fff; }
+
+      int next_bit()
+      {
+        d_sr = ((((d_sr >> 1) ^ d_sr) & 0x1) << 14) | (d_sr >> 1);
+        return d_sr & 0x1;
+      }
+
+      int next_byte ()
+      {
+        int	v = 0;
+        for(int i = 0; i < 8; i++) {
+          v >>= 1;
+          if(next_bit ())
+            v |= 0x80;
+        }
+        return v;
+      }
+    };
+
+  } /* namespace blocks */
+} /* namespace gr */
+
+#endif /* INCLUDED_GRI_LFSR_15_1_0_H */