AP_GPS_NMEA.h

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/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

//
// NMEA parser, adapted by Michael Smith from TinyGPS v9:
//
// TinyGPS - a small GPS library for Arduino providing basic NMEA parsing
// Copyright (C) 2008-9 Mikal Hart
// All rights reserved.
//
//

#pragma once

#include "AP_GPS.h"
#include "GPS_Backend.h"

class AP_GPS_NMEA : public AP_GPS_Backend
{
    friend class AP_GPS_NMEA_Test;

public:
    AP_GPS_NMEA(AP_GPS &_gps, AP_GPS::GPS_State &_state, AP_HAL::UARTDriver *_port);

    bool        read();

    static bool _detect(struct NMEA_detect_state &state, uint8_t data);

    const char *name() const override { return "NMEA"; }

private:
    enum _sentence_types {      //there are some more than 10 fields in some sentences , thus we have to increase these value.
        _GPS_SENTENCE_RMC = 32,
        _GPS_SENTENCE_GGA = 64,
        _GPS_SENTENCE_VTG = 96,
        _GPS_SENTENCE_OTHER = 0
    };

    bool                        _decode(char c);

    int16_t                     _from_hex(char a);

    static int32_t _parse_decimal_100(const char *p);

    uint32_t    _parse_degrees();

    bool                        _term_complete();

    bool _have_new_message(void);

    uint8_t _parity;                                                    
    bool _is_checksum_term;                                     
    char _term[15];                                                     
    uint8_t _sentence_type;                                     
    uint8_t _term_number;                                       
    uint8_t _term_offset;                                       
    bool _gps_data_good;                                        

    // The result of parsing terms within a message is stored temporarily until
    // the message is completely processed and the checksum validated.
    // This avoids the need to buffer the entire message.
    int32_t _new_time;                                                  
    int32_t _new_date;                                                  
    int32_t _new_latitude;                                      
    int32_t _new_longitude;                                     
    int32_t _new_altitude;                                      
    int32_t _new_speed;                                                 
    int32_t _new_course;                                        
    uint16_t _new_hdop;                                                 
    uint8_t _new_satellite_count;                       
    uint8_t _new_quality_indicator;                                     

    uint32_t _last_RMC_ms = 0;
    uint32_t _last_GGA_ms = 0;
    uint32_t _last_VTG_ms = 0;


    static const char _SiRF_init_string[];         
    static const char _MTK_init_string[];                  
    static const char _ublox_init_string[];        


    static const char _initialisation_blob[];
};