173 lines
5.0 KiB
C++
173 lines
5.0 KiB
C++
/***************************************************************************
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* Copyright (C) 2021 - 2022 by Federico Amedeo Izzo IU2NUO, *
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* Niccolò Izzo IU2KIN *
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* Frederik Saraci IU2NRO *
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* Silvano Seva IU2KWO *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, see <http://www.gnu.org/licenses/> *
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***************************************************************************/
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#ifndef M17_LINKSETUPFRAME_H
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#define M17_LINKSETUPFRAME_H
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#ifndef __cplusplus
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#error This header is C++ only!
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#endif
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#include <string>
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#include <array>
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#include "M17Datatypes.hpp"
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namespace M17
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{
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class M17FrameDecoder;
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/**
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* This class describes and handles an M17 Link Setup Frame.
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* By default the frame contains a broadcast destination address, unless a
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* specific address is set by calling the corresponding function.
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*/
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class M17LinkSetupFrame
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{
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public:
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/**
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* Constructor.
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*/
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M17LinkSetupFrame();
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/**
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* Destructor.
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*/
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~M17LinkSetupFrame();
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/**
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* Clear the frame content, filling it with zeroes and resetting the
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* destination address to broadcast.
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*/
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void clear();
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/**
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* Set source callsign.
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*
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* @param callsign: string containing the source callsign.
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*/
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void setSource(const std::string& callsign);
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/**
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* Get source callsign.
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*
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* @return: string containing the source callsign.
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*/
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std::string getSource();
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/**
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* Set destination callsign.
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*
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* @param callsign: string containing the destination callsign.
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*/
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void setDestination(const std::string& callsign);
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/**
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* Get destination callsign.
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*
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* @return: string containing the destination callsign.
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*/
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std::string getDestination();
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/**
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* Get stream type field.
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*
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* @return a copy of the frame's tream type field.
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*/
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streamType_t getType();
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/**
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* Set stream type field.
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*
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* @param type: stream type field to be written.
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*/
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void setType(streamType_t type);
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/**
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* Get metadata field.
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*
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* @return a reference to frame's metadata field, allowing for both read and
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* write access.
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*/
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meta_t& metadata();
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/**
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* Compute a new CRC over the frame content and update the corresponding
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* field.
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*/
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void updateCrc();
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/**
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* Check if frame data is valid that is, if the CRC computed over the LSF
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* fields matches the one carried by the LSF itself.
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*
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* @return true if CRC of LSF data matches the one stored in the LSF itself,
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* false otherwise.
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*/
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bool valid();
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/**
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* Get underlying data.
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*
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* @return a pointer to const uint8_t allowing direct access to LSF data.
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*/
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const uint8_t *getData();
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/**
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* Generate one of the six possible LSF chunks for embedding in data frame's
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* LICH field. Output is the Golay (24,12) encoded LSF chunk.
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*
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* @param segmentNum: segment number, between 0 and 5.
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* @return Golay (24,12) encoded LSF chunk.
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*/
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lich_t generateLichSegment(const uint8_t segmentNum);
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private:
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/**
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* Compute the CRC16 of a given chunk of data using the polynomial 0x5935
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* with an initial value set to 0xFFFF, as per M17 specification.
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*
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* \param data: pointer to the data block.
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* \param len: lenght of the data block, in bytes.
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* \return computed CRC16 over the data block.
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*/
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uint16_t crc16(const void *data, const size_t len);
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struct __attribute__((packed))
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{
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call_t dst; ///< Destination callsign
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call_t src; ///< Source callsign
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streamType_t type; ///< Stream type information
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meta_t meta; ///< Metadata
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uint16_t crc; ///< CRC
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}
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data; ///< Frame data.
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// Frame decoder class needs to access raw frame data
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friend class M17FrameDecoder;
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};
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} // namespace M17
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#endif // M17_LINKSETUPFRAME_H
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