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nmea.h /* * GearBox Project: Peer-Reviewed Open-Source Libraries for Robotics * http://gearbox.sf.net/ * Copyright (c) 2004-2008 Alex Brooks, Alexei Makarenko, Tobias Kaupp, Duncan Mercer * * This distribution is licensed to you under the terms described in * the LICENSE file included in this distribution. * */ #ifndef GBXGPSUTILACFR_NMEA_H #define GBXGPSUTILACFR_NMEA_H #include <vector> #include <string> /* for further info: http://www.kh-gps.de/nmea-faq.htm http://vancouver-webpages.com/peter/nmeafaq.txt NMEA-0183 sentence $aaccc,c--c*hh<CR><LF> || || || | || || || \________ <CR><LF> - End of sentence (0xOD 0xOA) || || |\__________ hh - Checksum field hexadecimal [optional] || || \___________ * - Checksum delimiter (0x2A) [optional] || |\_______________ c--c - Data sentence block || \________________ , - Field delimiter (0x2c) |\_____________________ aaccc - Address field/Command \______________________ $ - Start of sentence The optional checksum field consists of a "*" and two hex digits representing the exclusive OR of all characters between, but not including, the "$" and "*". A checksum is required on some sentences. */ namespace gbxgpsutilacfr { // class SOEXPORT NmeaException : public std::exception class NmeaException : public std::exception { public: NmeaException(const char *message) : message_(message) {} NmeaException(const std::string &message) : message_(message) {} virtual ~NmeaException() throw() {} virtual const char* what() const throw() { return message_.c_str(); } protected: std::string message_; }; #define MAX_SENTENCE_LEN 256 // When using class to send data, need to add checksum, when reciving data need to test checksum // Checksums are usually optional enum NmeaMessageOptions { TestChecksum, AddChecksum, DontTestOrAddChecksum }; // class SOEXPORT NmeaMessage{ class NmeaMessage { public: NmeaMessage(); NmeaMessage(const char *sentence, int testCheckSum=DontTestOrAddChecksum ); // Set up the internal data for a sentence. // May throw NmeaException if TestChecksum is specified. void setSentence(const char *data, int testCheckSum=DontTestOrAddChecksum ); // Do we only have the raw string? bool haveSentence() const { return haveSentence_; }; // Do we have parsed fields? bool haveTokens() const { return haveTokens_; }; // Do we have a valid checksum? bool haveValidChecksum() const { return checkSumOK_; }; // Have we checked the checksum? bool haveTestedChecksum()const { return haveCheckSum_; }; // calculate the checksum from sentence // May throw NmeaException. bool testChecksumOk(); // Return the raw sentence string const char* sentence() { return sentence_; }; // Return a single data token as a string std::string& getDataToken(int i) { return dataTokens_[i]; }; // Return the number of fields int numDataTokens() const { return dataTokens_.size(); }; //Tokenise the string that we received void parseTokens(); private: void init(); // May throw NmeaException. void addCheckSum(); // Do we only have the raw string ? bool haveSentence_; // Have we parsed data into tokens ? bool haveTokens_; // Have we a checksum and is it valid? bool haveCheckSum_; bool checkSumOK_; // The raw sentence, allow for terminator char sentence_[MAX_SENTENCE_LEN+1]; // The tokenised data std::vector<std::string> dataTokens_; }; } #endif

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