Merge branch 'dfsg-orig'

[debian/gnuradio] / gr-atsc / src / lib / atsci_sliding_correlator.h

diff --git a/gr-atsc/src/lib/atsci_sliding_correlator.h b/gr-atsc/src/lib/atsci_sliding_correlator.h
new file mode 100644 (file)
index 0000000..c01bc9a
--- /dev/null
+++ b/gr-atsc/src/lib/atsci_sliding_correlator.h
@@ -0,0 +1,83 @@
+/* -*- 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 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 _ATSC_SLIDING_CORRELATOR_H_
+#define _ATSC_SLIDING_CORRELATOR_H_
+
+#include <string.h>
+
+extern const unsigned char atsc_pn511[511];
+extern const unsigned char atsc_pn63[63];
+
+/*!
+ * \brief look for the PN 511 field sync pattern
+ */
+class atsci_sliding_correlator {
+ public:
+
+  atsci_sliding_correlator ();
+  ~atsci_sliding_correlator (){};
+
+  //! input hard decision bit, return correlation (0,511)
+  // Result is the number of wrong bits.  
+  // E.g., 0 -> perfect match; 511 -> all bits are wrong
+
+  int input_bit (int bit);
+
+  //! input sample, return correlation (0,511)
+  // Result is the number of wrong bits.  
+  // E.g., 0 -> perfect match; 511 -> all bits are wrong
+
+  int input_int (int sample){
+    return input_bit (sample < 0 ? 0 : 1);
+  }
+
+  //! input sample, return correlation (0,511)
+  // Result is the number of wrong bits.  
+  // E.g., 0 -> perfect match; 511 -> all bits are wrong
+
+  int input_float (float sample){
+    return input_bit (sample < 0 ? 0 : 1);
+  }
+
+  void reset () { input.reset (); }
+  
+ private:
+
+  typedef unsigned long        srblock;
+  static const int bits_per_char = 8;
+  static const int srblock_bitsize = sizeof (srblock) * bits_per_char;
+  static const int NSRBLOCKS = (511 + srblock_bitsize - 1) / srblock_bitsize;
+
+  class shift_reg {
+  public:
+    shift_reg ()  { reset (); }
+    void reset () { memset (d, 0, sizeof (d)); }
+    void shift_in (int bit);
+    srblock    d[NSRBLOCKS];
+  };
+
+  shift_reg    mask;           // pattern we're looking for
+  shift_reg    input;          // current input window
+  shift_reg    and_mask;       // bits to consider
+};
+
+#endif /* _ATSC_SLIDING_CORRELATOR_H_ */