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

/*

 * Copyright 2005,2006 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_GR_OFDM_FRAME_SINK_H

#define INCLUDED_GR_OFDM_FRAME_SINK_H

#include <gr_sync_block.h>

#include <gr_msg_queue.h>

class gr_ofdm_frame_sink;

typedef boost::shared_ptr<gr_ofdm_frame_sink> gr_ofdm_frame_sink_sptr;

gr_ofdm_frame_sink_sptr 

gr_make_ofdm_frame_sink (gr_msg_queue_sptr target_queue, unsigned int occupied_tones);

/*!

 * \brief Given a stream of bits and access_code flags, assemble packets.

 * \ingroup sink

 *

 * input: stream of bytes from gr_correlate_access_code_bb

 * output: none.  Pushes assembled packet into target queue

 *

 * The framer expects a fixed length header of 2 16-bit shorts

 * containing the payload length, followed by the payload.  If the 

 * 2 16-bit shorts are not identical, this packet is ignored.  Better

 * algs are welcome.

 *

 * The input data consists of bytes that have two bits used.

 * Bit 0, the LSB, contains the data bit.

 * Bit 1 if set, indicates that the corresponding bit is the

 * the first bit of the packet.  That is, this bit is the first

 * one after the access code.

 */

class gr_ofdm_frame_sink : public gr_sync_block

{

  friend gr_ofdm_frame_sink_sptr 

  gr_make_ofdm_frame_sink (gr_msg_queue_sptr target_queue, unsigned int occupied_tones);

 private:

  enum state_t {STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER};

  static const int MAX_PKT_LEN    = 4096;

  static const int HEADERBYTELEN   = 4;

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

  state_t            d_state;

  unsigned int       d_header;                        // header bits

  int                     d_headerbytelen_cnt;        // how many so far

  unsigned char      *d_bytes_out;              // hold the current bytes produced by the demapper    

  unsigned int       d_occupied_carriers;

  unsigned int       d_byte_offset;

  unsigned int       d_partial_byte;

  unsigned char      d_packet[MAX_PKT_LEN];        // assembled payload

  int                      d_packetlen;                // length of packet

  int                d_packet_whitener_offset;  // offset into whitener string to use

  int                     d_packetlen_cnt;                // how many so far

 protected:

  gr_ofdm_frame_sink(gr_msg_queue_sptr target_queue, unsigned int occupied_tones);

  void enter_search();

  void enter_have_sync();

  void enter_have_header();

  bool header_ok()

  {

    // confirm that two copies of header info are identical

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

  }

  unsigned char bpsk_slicer(gr_complex x);

  unsigned int bpsk_demapper(const gr_complex *in,

                             unsigned char *out);  

 public:

  ~gr_ofdm_frame_sink();

  int work(int noutput_items,

           gr_vector_const_void_star &input_items,

           gr_vector_void_star &output_items);

};

#endif /* INCLUDED_GR_OFDM_FRAME_SINK_H */