/* -*- c++ -*- */ /* Copyright 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_DIGITAL_PACKET_HEADER_DEFAULT_H #define INCLUDED_DIGITAL_PACKET_HEADER_DEFAULT_H #include <gnuradio/tags.h> #include <gnuradio/digital/api.h> #include <boost/enable_shared_from_this.hpp> #include <boost/crc.hpp> namespace gr { namespace digital { /*! * \brief Default header formatter for digital packet transmission. * \ingroup packet_operators_blk * * \details * For bursty/packetized digital transmission, packets are usually prepended * with a packet header, containing the number of bytes etc. * This class is not a block, but a tool to create these packet header. * * This is a default packet header (see header_formatter()) for a description * on the header format). To create other header, derive packet header creator * classes from this function. * * gr::digital::packet_headergenerator_bb uses header generators derived from * this class to create packet headers from data streams. */ class DIGITAL_API packet_header_default : public boost::enable_shared_from_this<gr::digital::packet_header_default> { public: typedef boost::shared_ptr<packet_header_default> sptr; packet_header_default(long header_len, const std::string &len_tag_key="packet_len", const std::string &num_tag_key="packet_num", int bits_per_byte=1); virtual ~packet_header_default(); sptr base() { return shared_from_this(); }; sptr formatter() { return shared_from_this(); }; void set_header_num(unsigned header_num) { d_header_number = header_num; }; long header_len() { return d_header_len; }; pmt::pmt_t len_tag_key() { return d_len_tag_key; }; /*! * \brief Encodes the header information in the given tags into bits and places them into \p out * * Uses the following header format: * Bits 0-11: The packet length (what was stored in the tag with key \p len_tag_key) * Bits 12-23: The header number (counts up everytime this function is called) * Bit 24-31: 8-Bit CRC * All other bits: Are set to zero * * If the header length is smaller than 32, bits are simply left out. For this * reason, they always start with the LSB. * * However, it is recommended to stay above 32 Bits, in order to have a working * CRC. */ virtual bool header_formatter(long packet_len, unsigned char *out, const std::vector<tag_t> &tags=std::vector<tag_t>()); /*! * \brief Inverse function to header_formatter(). * * Reads the bit stream in \p header and writes a corresponding tag into \p tags. */ virtual bool header_parser( const unsigned char *header, std::vector<tag_t> &tags); static sptr make(long header_len, const std::string &len_tag_key="packet_len", const std::string &num_tag_key="packet_num", int bits_per_byte=1); protected: long d_header_len; pmt::pmt_t d_len_tag_key; pmt::pmt_t d_num_tag_key; int d_bits_per_byte; unsigned d_header_number; unsigned d_mask; boost::crc_optimal<8, 0x07, 0xFF, 0x00, false, false> d_crc_impl; }; } // namespace digital } // namespace gr #endif /* INCLUDED_DIGITAL_PACKET_HEADER_DEFAULT_H */