text: /* -*- 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 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., 59 Temple Place - Suite 330,
   * Boston, MA 02111-1307, USA.
   */
  
  #ifndef INCLUDED_UCLA_IEEE802_15_4_PACKET_SINK_H
  #define INCLUDED_UCLA_IEEE802_15_4_PACKET_SINK_H
  
  #include <gr_sync_block.h>
  #include <gr_msg_queue.h>
  
  class ucla_ieee802_15_4_packet_sink;
  typedef boost::shared_ptr<ucla_ieee802_15_4_packet_sink> ucla_ieee802_15_4_packet_sink_sptr;
  
  ucla_ieee802_15_4_packet_sink_sptr 
  ucla_make_ieee802_15_4_packet_sink (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
   */
  class ucla_ieee802_15_4_packet_sink : public gr_sync_block
  {
    friend ucla_ieee802_15_4_packet_sink_sptr 
    ucla_make_ieee802_15_4_packet_sink (gr_msg_queue_sptr target_queue,
  				int threshold);
  
  private:
    enum state_t {STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER};
  
    static const int MSG_LEN_POS   = 8+1;         // 8 byte sos header, 1 byte AM type
    static const int MAX_PKT_LEN    = 128 - MSG_LEN_POS - 1; // remove header and CRC
  
    //static const unsigned int CHIP_MAPPING[];     // will hold the mapping between chip and symbols
  
    gr_msg_queue_sptr  d_target_queue;		// where to send the packet when received
    unsigned int       d_sync_vector;		// 802.15.4 standard is 4x 0 bytes and 1x0xA7
    unsigned int	     d_threshold;		// how many bits may be wrong in sync vector
  
    state_t            d_state;
  
    unsigned int       d_shift_reg;		// used to look for sync_vector
    int                d_preamble_cnt;            // count on where we are in preamble
    int                d_chip_cnt;                // counts the chips collected
  
    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
    int		     d_payload_cnt;		// how many bytes in payload
    int                d_processed;
  
  protected:
    ucla_ieee802_15_4_packet_sink(gr_msg_queue_sptr target_queue,
  				int threshold);
    
    void enter_search();
    void enter_have_sync();
    void enter_have_header(int payload_len);
    unsigned char decode_chips(unsigned int chips);
    int slice(float x) { return x > 0 ? 1 : 0; }
    
    bool header_ok()
    {
      // might do some checks on the header later...
      return 1;
    }
  
  
  public:
    ~ucla_ieee802_15_4_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 */
  