/* -*- c++ -*- */

/*

 * Copyright 2005 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_PACKET_SINK_H

#define INCLUDED_GR_PACKET_SINK_H

#include <gr_core_api.h>

#include <gr_sync_block.h>

#include <gr_msg_queue.h>

class gr_packet_sink;

typedef boost::shared_ptr<gr_packet_sink> gr_packet_sink_sptr;

GR_CORE_API gr_packet_sink_sptr 

gr_make_packet_sink (const std::vector<unsigned char>& sync_vector,

                     gr_msg_queue_sptr target_queue,

                     int threshold = -1                        // -1 -> use default

                     );

/*!

 * \brief process received  bits looking for packet sync, header, and process bits into packet

 * \ingroup sink_blk

 */

class GR_CORE_API gr_packet_sink : public gr_sync_block

{

  friend GR_CORE_API gr_packet_sink_sptr 

  gr_make_packet_sink (const std::vector<unsigned char>& sync_vector,

                       gr_msg_queue_sptr target_queue,

                       int threshold);

 private:

  enum state_t {STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER};

  static const int MAX_PKT_LEN    = 4096;

  static const int HEADERBITLEN   = 32;

  gr_msg_queue_sptr  d_target_queue;                // where to send the packet when received

  unsigned long long d_sync_vector;                // access code to locate start of packet

  unsigned int             d_threshold;                // how many bits may be wrong in sync vector

  state_t            d_state;

  unsigned long long d_shift_reg;                // used to look for sync_vector

  unsigned int       d_header;                        // header bits

  int                     d_headerbitlen_cnt;        // how many so far

  unsigned char      d_packet[MAX_PKT_LEN];        // assembled payload

  unsigned char             d_packet_byte;                // byte being assembled

  int                     d_packet_byte_index;        // which bit of d_packet_byte we're working on

  int                      d_packetlen;                // length of packet

  int                     d_packetlen_cnt;                // how many so far

 protected:

  gr_packet_sink(const std::vector<unsigned char>& sync_vector, 

                 gr_msg_queue_sptr target_queue,

                 int threshold);

  void enter_search();

  void enter_have_sync();

  void enter_have_header(int payload_len);

  int slice(float x) { return x > 0 ? 1 : 0; }

  bool header_ok()

  {

    // confirm that two copies of header info are identical

    return ((d_header >> 16) ^ (d_header & 0xffff)) == 0;

  }

  int header_payload_len()

  {

    // header consists of two 16-bit shorts in network byte order

    int t = (d_header >> 16) & 0xffff;

    return t;

  }

 public:

  ~gr_packet_sink();

  int work(int noutput_items,

           gr_vector_const_void_star &input_items,

           gr_vector_void_star &output_items);

  //! return true if we detect carrier

  bool carrier_sensed() const

  {

    return d_state != STATE_SYNC_SEARCH;

  }

};

#endif /* INCLUDED_GR_PACKET_SINK_H */