gpsparser.h

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#ifndef LIBPROPELLER_GPSPARSER_H_
#define LIBPROPELLER_GPSPARSER_H_

#include "libpropeller/serial/serial.h"

class GPSParser {
public:

    bool Start(const int rx_pin, const int tx_pin, const int baud) {
        gps_serial_.Stop();
        next_character_position_ = 0;
        gps_serial_.Start(rx_pin, tx_pin, baud);

        recording_sentence_ = false;
        return true;
    }

    ~GPSParser() {
        gps_serial_.Stop();
    }

    char * Get() {
        return Get(internal_buffer_);
    }

    char * Get(char string[], const int maxBytes = kNmeaMaxLength) {
        for (;;) {

            int byte = gps_serial_.Get(0);
            if (byte == -1) return NULL;

            if (next_character_position_ == 6) {
                CheckForPGTOP(string);
            }


            if (recording_sentence_ == false && byte != kSentenceStartCharacter) {
                /* Do nothing */
            } else if (byte == '\r' || byte == '\n') {
                return TerminateString(string);
            } else {
                //Have a valid byte, now need to add to buffer
                recording_sentence_ = true;
                string[next_character_position_++] = byte;
            }

            if (next_character_position_ == maxBytes - 1) {
                return TerminateString(string);
            }
        }
    }

protected:
    Serial gps_serial_;

private:
    static const int kNmeaMaxLength = 85;
    static const int kBufferSize = kNmeaMaxLength;
    static const char kSentenceStartCharacter = '$';

    int next_character_position_;
    char internal_buffer_[kBufferSize]; //Holds 1 NMEA string
    bool recording_sentence_;

    char * TerminateString(char string[]) {
        string[next_character_position_] = 0; //Null terminator
        next_character_position_ = 0; //Reset nextCharacterPosition
        recording_sentence_ = false;
        return string; //Return pointer
    }

    void CheckForPGTOP(char string[]) {
        if (string[1] == 'P' &&
                string[2] == 'G' &&
                string[3] == 'T' &&
                string[4] == 'O' &&
                string[5] == 'P') {
            next_character_position_ = 0;
            recording_sentence_ = false;
        }
    }

    Serial * getSerial(void) {
        return &gps_serial_;
    }
public:
    friend class UnityTests;
};



#endif // LIBPROPELLER_GPSPARSER_H_