Merged r4605:4612 from jcorgan/glfsr branch into trunk. Implements Galois LFSR source block of degree 1 through 32.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@4613 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 54 insertions, 0 deletions

diff --git a/gnuradio-core/src/lib/general/gri_glfsr.h b/gnuradio-core/src/lib/general/gri_glfsr.h
new file mode 100644
index 000000000..7fde99370
--- /dev/null
+++ b/gnuradio-core/src/lib/general/gri_glfsr.h
@@ -0,0 +1,54 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2007 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., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef INCLUDED_GRI_GLFSR_H
+#define INCLUDED_GRI_GLFSR_H
+
+/*!
+ * \brief Galois Linear Feedback Shift Register using specified polynomial mask
+ *
+ * Generates a maximal length pseudo-random sequence of length 2^degree-1
+ */
+
+class gri_glfsr
+{
+ private:
+  int d_shift_register;
+  int d_mask;
+
+ public:
+
+  gri_glfsr(int mask, int seed) { d_shift_register = seed; d_mask = mask; }
+  static int glfsr_mask(int degree);
+
+  unsigned char next_bit() {
+    unsigned char bit = d_shift_register & 1;
+    d_shift_register >>= 1;
+    if (bit)
+      d_shift_register ^= d_mask;
+    return bit;
+  }
+
+  int mask() const { return d_mask; }
+};
+
+#endif /* INCLUDED_GRI_GLFSR_H */