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Diffstat (limited to 'gr-digital/include/digital_packet_sink.h')
| -rw-r--r-- | gr-digital/include/digital_packet_sink.h | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/gr-digital/include/digital_packet_sink.h b/gr-digital/include/digital_packet_sink.h new file mode 100644 index 000000000..7ab41c0ef --- /dev/null +++ b/gr-digital/include/digital_packet_sink.h @@ -0,0 +1,131 @@ +/* -*- c++ -*- */ +/* + * Copyright 2005,2012 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 <digital_api.h> +#include <gr_sync_block.h> +#include <gr_msg_queue.h> + +class digital_packet_sink; +typedef boost::shared_ptr<digital_packet_sink> digital_packet_sink_sptr; + +DIGITAL_API digital_packet_sink_sptr +digital_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 + * + * input: stream of symbols to be sliced. + * + * output: none. Pushes assembled packet into target queue + * + * The packet sink takes in a stream of binary symbols that are sliced + * around 0. The bits are then checked for the \p sync_vector to + * determine find and decode the packet. It then 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. + * + * This block is not very useful anymore as it only works with 2-level + * modulations such as BPSK or GMSK. The block can generally be + * replaced with a correlate access code and frame sink blocks. + * + * \param sync_vector The synchronization vector as a vector of 1's and 0's. + * \param target_queue The message queue that packets are sent to. + * \param threshold Number of bits that can be incorrect in the \p sync_vector. + */ +class DIGITAL_API digital_packet_sink : public gr_sync_block +{ + friend DIGITAL_API digital_packet_sink_sptr + digital_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: + digital_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: + ~digital_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 */ |