digital: moved simple_correlator (inverse of simple_framer) to gr-digital.

2 files changed, 108 insertions, 0 deletions

diff --git a/gr-digital/include/CMakeLists.txt b/gr-digital/include/CMakeLists.txt
index f863b2875..ad5baec87 100644
--- a/gr-digital/include/CMakeLists.txt
+++ b/gr-digital/include/CMakeLists.txt
@@ -123,6 +123,7 @@ install(FILES
     digital_scrambler_bb.h
     digital_simple_framer.h
     digital_simple_framer_sync.h
+    digital_simple_correlator.h
     DESTINATION ${GR_INCLUDE_DIR}/gnuradio
     COMPONENT "digital_devel"
 )
diff --git a/gr-digital/include/digital_simple_correlator.h b/gr-digital/include/digital_simple_correlator.h
new file mode 100644
index 000000000..716c6995c
--- /dev/null
+++ b/gr-digital/include/digital_simple_correlator.h
@@ -0,0 +1,107 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2004,2013 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_GR_SIMPLE_CORRELATOR_H
+#define INCLUDED_GR_SIMPLE_CORRELATOR_H
+
+#include <digital_api.h>
+#include <gr_block.h>
+
+class digital_simple_correlator;
+typedef boost::shared_ptr<digital_simple_correlator> digital_simple_correlator_sptr;
+
+DIGITAL_API digital_simple_correlator_sptr digital_make_simple_correlator(int payload_bytesize);
+
+/*!
+ * \brief inverse of simple_framer (more or less)
+ * \ingroup sync_blk
+ */
+class DIGITAL_API digital_simple_correlator : public gr_block
+{
+ private:
+  static const int OVERSAMPLE = 8;
+  enum state_t { ST_LOOKING, ST_UNDER_THRESHOLD, ST_LOCKED };
+
+  int            d_payload_bytesize;
+  state_t        d_state;
+  unsigned int   d_osi;			// over sample index [0,OVERSAMPLE-1]
+  unsigned int   d_transition_osi;	// first index where Hamming dist < thresh
+  unsigned int   d_center_osi;		// center of bit
+  unsigned long long int d_shift_reg[OVERSAMPLE];
+  int            d_bblen;		// length of bitbuf
+  unsigned char *d_bitbuf;		// demodulated bits
+  unsigned char *d_pktbuf;		// temp packet buf
+  int            d_bbi;			// bitbuf index
+
+  static const int AVG_PERIOD = 512;	// must be power of 2 (for freq offset correction)
+  int   d_avbi;
+  float d_avgbuf[AVG_PERIOD];
+  float d_avg;
+  float d_accum;
+
+#ifdef DEBUG_SIMPLE_CORRELATOR
+  FILE *d_debug_fp;    // binary log file
+#endif
+
+  friend GR_CORE_API digital_simple_correlator_sptr
+    digital_make_simple_correlator(int payload_bytesize);
+  digital_simple_correlator(int payload_bytesize);
+
+  inline int slice(float x)
+  {
+    return x >= d_avg ? 1 : 0;
+  }
+
+  void update_avg(float x);
+
+  void enter_locked();
+  void enter_under_threshold();
+  void enter_looking();
+
+  static int add_index(int a, int b)
+  {
+    int t = a + b;
+    if(t >= OVERSAMPLE)
+      t -= OVERSAMPLE;
+    assert(t >= 0 && t < OVERSAMPLE);
+    return t;
+  }
+
+  static int sub_index(int a, int b)
+  {
+    int t = a - b;
+    if(t < 0)
+      t += OVERSAMPLE;
+    assert(t >= 0 && t < OVERSAMPLE);
+    return t;
+  }
+
+ public:
+  ~digital_simple_correlator();
+
+  int general_work(int noutput_items,
+                   gr_vector_int &ninput_items,
+                   gr_vector_const_void_star &input_items,
+                   gr_vector_void_star &output_items);
+};
+
+#endif /* INCLUDED_GR_SIMPLE_CORRELATOR_H */