GNU Radio 2.x: gr_packet_sink.h Source File

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# gr_packet_sink.h

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    00001 /* -*- c++ -*- */
    00002 /*
    00003  * Copyright 2005 Free Software Foundation, Inc.
    00004  *
    00005  * This file is part of GNU Radio
    00006  *
    00007  * GNU Radio is free software; you can redistribute it and/or modify
    00008  * it under the terms of the GNU General Public License as published by
    00009  * the Free Software Foundation; either version 2, or (at your option)
    00010  * any later version.
    00011  *
    00012  * GNU Radio is distributed in the hope that it will be useful,
    00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
    00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00015  * GNU General Public License for more details.
    00016  *
    00017  * You should have received a copy of the GNU General Public License
    00018  * along with GNU Radio; see the file COPYING.  If not, write to
    00019  * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
    00020  * Boston, MA 02111-1307, USA.
    00021  */
    00022
    00023 #ifndef INCLUDED_GR_PACKET_SINK_H
    00024 #define INCLUDED_GR_PACKET_SINK_H
    00025
    00026 #include <gr_sync_block.h>
    00027 #include <gr_msg_queue.h>
    00028
    00029 class gr_packet_sink;
    00030 typedef boost::shared_ptr<gr_packet_sink> gr_packet_sink_sptr;
    00031
    00032 gr_packet_sink_sptr
    00033 gr_make_packet_sink (const std::vector<unsigned char>& sync_vector,
    00034                      gr_msg_queue_sptr target_queue,
    00035                      int threshold = -1                 // -1 -> use default
    00036                      );
    00041 class gr_packet_sink : public gr_sync_block
    00042 {
    00043   friend gr_packet_sink_sptr
    00044   gr_make_packet_sink (const std::vector<unsigned char>& sync_vector,
    00045                        gr_msg_queue_sptr target_queue,
    00046                        int threshold);
    00047
    00048  private:
    00049   enum state_t {STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER};
    00050
    00051   static const int MAX_PKT_LEN    = 4096;
    00052   static const int HEADERBITLEN   = 32;
    00053
    00054   gr_msg_queue_sptr  d_target_queue;            // where to send the packet when received
    00055   unsigned long long d_sync_vector;             // access code to locate start of packet
    00056   unsigned int       d_threshold;               // how many bits may be wrong in sync vector
    00057
    00058   state_t            d_state;
    00059
    00060   unsigned long long d_shift_reg;               // used to look for sync_vector
    00061
    00062   unsigned int       d_header;                  // header bits
    00063   int                d_headerbitlen_cnt;        // how many so far
    00064
    00065   unsigned char      d_packet[MAX_PKT_LEN];     // assembled payload
    00066   unsigned char      d_packet_byte;             // byte being assembled
    00067   int                d_packet_byte_index;       // which bit of d_packet_byte we're working on
    00068   int                d_packetlen;               // length of packet
    00069   int                d_packetlen_cnt;           // how many so far
    00070
    00071  protected:
    00072   gr_packet_sink(const std::vector<unsigned char>& sync_vector,
    00073                  gr_msg_queue_sptr target_queue,
    00074                  int threshold);
    00075
    00076   void enter_search();
    00077   void enter_have_sync();
    00078   void enter_have_header(int payload_len);
    00079
    00080   int slice(float x) { return x > 0 ? 1 : 0; }
    00081
    00082   bool header_ok()
    00083   {
    00084     // confirm that two copies of header info are identical
    00085     return ((d_header >> 16) ^ (d_header & 0xffff)) == 0;
    00086   }
    00087
    00088   int header_payload_len()
    00089   {
    00090     // header consists of two 16-bit shorts in network byte order
    00091     int t = (d_header >> 16) & 0xffff;
    00092     return t;
    00093   }
    00094
    00095  public:
    00096   ~gr_packet_sink();
    00097
    00098   int work(int noutput_items,
    00099            gr_vector_const_void_star &input_items,
    00100            gr_vector_void_star &output_items);
    00101 };
    00102
    00103 #endif /* INCLUDED_GR_PACKET_SINK_H */