mirror of
https://github.com/ShaYmez/NXDNClients.git
synced 2024-11-03 14:41:16 -05:00
161 lines
3.8 KiB
C++
161 lines
3.8 KiB
C++
/*
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* Copyright (C) 2018 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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#include "GPSHandler.h"
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#include "Utils.h"
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#include <cstdint>
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#include <cstdio>
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#include <cassert>
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#include <cstring>
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const unsigned char NXDN_DATA_TYPE_GPS = 0x06U;
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const unsigned int NXDN_DATA_LENGTH = 20U;
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const unsigned int NXDN_DATA_MAX_LENGTH = 16U * NXDN_DATA_LENGTH;
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CGPSHandler::CGPSHandler(const std::string& callsign, const std::string& suffix, CAPRSWriter* writer) :
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m_callsign(callsign),
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m_writer(writer),
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m_data(NULL),
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m_length(0U),
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m_source(),
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m_suffix(suffix)
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{
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assert(!callsign.empty());
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assert(writer != NULL);
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m_data = new unsigned char[NXDN_DATA_MAX_LENGTH];
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reset();
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}
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CGPSHandler::~CGPSHandler()
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{
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delete[] m_data;
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}
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void CGPSHandler::processHeader(const std::string& source)
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{
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reset();
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m_source = source;
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}
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void CGPSHandler::processData(const unsigned char* data)
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{
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assert(data != NULL);
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::memcpy(m_data + m_length, data + 1U, NXDN_DATA_LENGTH);
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m_length += NXDN_DATA_LENGTH;
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if (data[0U] == 0x00U) {
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processNMEA();
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reset();
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}
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}
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void CGPSHandler::processEnd()
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{
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reset();
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}
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void CGPSHandler::reset()
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{
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::memset(m_data, 0x00U, NXDN_DATA_MAX_LENGTH);
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m_length = 0U;
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m_source.clear();
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}
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void CGPSHandler::processNMEA()
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{
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if (m_data[0U] != NXDN_DATA_TYPE_GPS)
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return;
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if (::memcmp(m_data + 1U, "$G", 2U) != 0)
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return;
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if (::strchr((char*)(m_data + 1U), '*') == NULL)
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return;
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if (!checkXOR())
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return;
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if (::memcmp(m_data + 4U, "RMC", 3U) != 0) {
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CUtils::dump("Unhandled NMEA sentence", (unsigned char*)(m_data + 1U), m_length - 1U);
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return;
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}
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// Parse the $GxRMC string into tokens
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char* pRMC[20U];
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::memset(pRMC, 0x00U, 20U * sizeof(char*));
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unsigned int nRMC = 0U;
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char* p = NULL;
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char* d = (char*)(m_data + 1U);
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while ((p = ::strtok(d, ",\r\n")) != NULL && nRMC < 20U) {
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pRMC[nRMC++] = p;
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d = NULL;
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}
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// Is there any position data?
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if (pRMC[3U] == NULL || pRMC[4U] == NULL || pRMC[5U] == NULL || pRMC[6U] == NULL || ::strlen(pRMC[3U]) == 0U || ::strlen(pRMC[4U]) == 0U || ::strlen(pRMC[5U]) == 0 || ::strlen(pRMC[6U]) == 0)
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return;
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// Is it a valid GPS fix?
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if (::strcmp(pRMC[2U], "A") != 0)
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return;
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double latitude = ::atof(pRMC[3U]);
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double longitude = ::atof(pRMC[5U]);
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std::string source = m_source;
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if (!m_suffix.empty()) {
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source.append("-");
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source.append(m_suffix.substr(0U, 1U));
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}
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char output[300U];
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if (pRMC[7U] != NULL && pRMC[8U] != NULL && ::strlen(pRMC[7U]) > 0U && ::strlen(pRMC[8U]) > 0U) {
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int bearing = ::atoi(pRMC[8U]);
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int speed = ::atoi(pRMC[7U]);
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::sprintf(output, "%s>APDPRS,NXDN*,qAR,%s:!%07.2lf%s/%08.2lf%sr%03d/%03d via MMDVM",
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source.c_str(), m_callsign.c_str(), latitude, pRMC[4U], longitude, pRMC[6U], bearing, speed);
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} else {
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::sprintf(output, "%s>APDPRS,NXDN*,qAR,%s:!%07.2lf%s/%08.2lf%sr via MMDVM",
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source.c_str(), m_callsign.c_str(), latitude, pRMC[4U], longitude, pRMC[6U]);
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}
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m_writer->write(output);
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}
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bool CGPSHandler::checkXOR() const
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{
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char* p1 = ::strchr((char*)m_data, '$');
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char* p2 = ::strchr((char*)m_data, '*');
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unsigned char res = 0U;
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for (char* q = p1 + 1U; q < p2; q++)
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res ^= *q;
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char buffer[10U];
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::sprintf(buffer, "%02X", res);
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return ::memcmp(buffer, p2 + 1U, 2U) == 0;
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}
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