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176 lines
6.9 KiB
176 lines
6.9 KiB
/*
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* Copyright (C) 2012-2014 by Jonathan Naylor G4KLX
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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 2 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, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef SplitController_H
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#define SplitController_H
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#include "GatewayProtocolHandler.h"
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#include "DStarDefines.h"
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#include "RingBuffer.h"
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#include "Timer.h"
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#include "Modem.h"
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#include "Utils.h"
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#include "StdCompat.h"
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#include <string>
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#include <vector>
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#include <cstdint>
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/*
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* CAMBESlot - Holds one sequence-number slot's worth of AMBE data from all receivers.
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*
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* D-Star transmits 21 frames per super-frame (one data sync + 20 voice frames).
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* CSplitController maintains 21 CAMBESlot objects, indexed by the D-Star sequence
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* number. When AMBE data arrives from multiple receivers for the same slot, the
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* copy with the fewest AMBE error bits (lowest m_errors) is kept as the best copy.
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*
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* m_valid[n] - true when receiver n has contributed data for this slot.
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* m_end[n] - true when receiver n flagged end-of-transmission for this slot.
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* m_best - index of the receiver whose data is currently stored in m_ambe.
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* m_timer - deadline by which the slot must be forwarded to the repeater,
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* even if not all receivers have responded.
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*/
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class CAMBESlot {
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public:
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CAMBESlot(unsigned int rxCount);
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~CAMBESlot();
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void reset();
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// Returns true when no receiver has deposited data yet (m_length == 0).
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bool isFirst() const;
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bool* m_valid;
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unsigned int m_errors;
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unsigned int m_best;
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unsigned char* m_ambe;
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unsigned int m_length;
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bool* m_end;
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CTimer m_timer;
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private:
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unsigned int m_rxCount;
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};
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/*
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* CSplitController - Multi-receiver split-site repeater controller using UDP.
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*
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* Allows multiple geographically separated receive sites to feed a single
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* repeater. Each receiver and transmitter connects to the controller via UDP
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* using the CGatewayProtocolHandler (ircDDB gateway wire protocol).
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*
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* Network protocol:
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* Receivers send NETWORK_HEADER and NETWORK_DATA packets, each containing
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* the stream ID, sequence number, AMBE payload, and an error count.
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* Transmitters receive NETWORK_HEADER and NETWORK_DATA forwarded by the
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* controller's transmit() method.
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* All remotes register by sending NETWORK_REGISTER with their name string;
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* the controller maps names to IP:port and runs a REGISTRATION_TIMEOUT timer
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* that expires if a remote goes silent.
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*
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* AMBE selection (best-copy diversity):
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* For each D-Star sequence number slot (0-20), AMBE frames from all registered
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* receivers are buffered in the corresponding CAMBESlot. The frame with the
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* fewest AMBE error bits wins and is forwarded to the repeater when the slot
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* timer expires. If no receiver provides data for a slot, a silence frame
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* (NULL_FRAME_DATA_BYTES) is substituted.
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*
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* Resequencing:
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* m_inSeqNo tracks the next expected sequence number from any receiver.
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* m_outSeqNo tracks the next slot to be forwarded to the repeater.
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* Out-of-order packets that are more than 18 slots ahead are discarded.
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*
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* Header forwarding (sendHeader()):
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* Deferred until the first data slot is ready to be forwarded. This ensures
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* the repeater receives header + data without a gap, and means m_headerSent
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* guards against duplicate header injection.
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*
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* timeout: per-slot wait time in milliseconds added to each slot's timer on
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* top of the expected frame arrival time. Increasing timeout improves
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* diversity at the cost of added latency.
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*/
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class CSplitController : public CModem {
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public:
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CSplitController(const std::string& localAddress, unsigned int localPort, const std::vector<std::string>& transmitterNames, const std::vector<std::string>& receiverNames, unsigned int timeout);
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virtual ~CSplitController();
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virtual bool start();
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virtual unsigned int getSpace();
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virtual bool isTXReady();
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virtual bool writeHeader(const CHeaderData& header);
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virtual bool writeData(const unsigned char* data, unsigned int length, bool end);
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private:
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void entry();
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CGatewayProtocolHandler m_handler;
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std::vector<std::string> m_transmitterNames;
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std::vector<std::string> m_receiverNames;
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unsigned int m_timeout;
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unsigned int m_txCount;
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unsigned int m_rxCount;
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in_addr* m_txAddresses;
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unsigned int* m_txPorts;
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CTimer** m_txTimers;
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in_addr* m_rxAddresses;
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unsigned int* m_rxPorts;
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CTimer** m_rxTimers;
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CRingBuffer<unsigned char> m_txData;
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uint16_t m_outId;
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uint8_t m_outSeq;
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CTimer m_endTimer;
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bool m_listening;
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uint8_t m_inSeqNo;
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uint8_t m_outSeqNo;
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unsigned char* m_header;
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uint16_t* m_id;
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bool* m_valid;
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CAMBESlot** m_slots;
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bool m_headerSent;
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unsigned int* m_packets;
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unsigned int* m_best;
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unsigned int* m_missed;
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unsigned int m_silence;
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// Drains m_txData and forwards header/data/EOT to all registered transmitters.
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void transmit();
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// Reads all pending UDP packets and dispatches them to processHeader/processAMBE
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// or updates remote registrations.
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void receive();
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// Advances all timers by ms; expires slot timers and forwards data to m_rxData.
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void timers(unsigned int ms);
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// Records a header from receiver n. First header starts the slot timers and
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// initialises per-receiver tracking; subsequent headers from other receivers
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// are validated by memcmp against the first.
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void processHeader(unsigned int n, uint16_t id, const unsigned char* header, unsigned int length);
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// Deposits an AMBE frame from receiver n into the appropriate sequence slot.
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// Keeps the frame with the lowest error count; discards frames > 18 slots ahead.
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void processAMBE(unsigned int n, uint16_t id, const unsigned char* ambe, unsigned int length, uint8_t seqNo, unsigned char errors);
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// Returns true when all valid receivers have signalled end-of-transmission
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// and none are still active in this slot.
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bool isEnd(const CAMBESlot& slot) const;
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// Queues the buffered header into m_rxData; must be called with m_mutex held.
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void sendHeader();
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// Logs per-receiver packet counts, best-copy proportions, and missed frames.
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void printStats() const;
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};
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#endif
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