// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
//
//  SiRF Binary GPS driver for ArduPilot and ArduPilotMega.
//	Code by Michael Smith.
//
//	This library is free software; you can redistribute it and / or
//	modify it under the terms of the GNU Lesser General Public
//	License as published by the Free Software Foundation; either
//	version 2.1 of the License, or (at your option) any later version.
//
#ifndef __AP_GPS_SIRF_H__
#define __AP_GPS_SIRF_H__

#include <AP_HAL.h>
#include <AP_Common.h>
#include "GPS.h"

#define SIRF_SET_BINARY "$PSRF100,0,38400,8,1,0*3C"

class AP_GPS_SIRF : public GPS {
public:
	AP_GPS_SIRF() : 
		GPS(),
		_step(0),
		_gather(false),
		_payload_length(0),
		_payload_counter(0),
		_msg_id(0)
		{}

    virtual void        init(AP_HAL::UARTDriver *s, enum GPS_Engine_Setting nav_setting = GPS_ENGINE_NONE);
    virtual bool        read();
	static bool         _detect(uint8_t data);

private:
    struct PACKED sirf_geonav {
        uint16_t fix_invalid;
        uint16_t fix_type;
        uint16_t week;
        uint32_t time;
        uint16_t year;
        uint8_t month;
        uint8_t day;
        uint8_t hour;
        uint8_t minute;
        uint16_t second;
        uint32_t satellites_used;
        int32_t latitude;
        int32_t longitude;
        int32_t altitude_ellipsoid;
        int32_t altitude_msl;
        int8_t map_datum;
        int16_t ground_speed;
        int16_t ground_course;
        int16_t res1;
        int16_t climb_rate;
        uint16_t heading_rate;
        uint32_t horizontal_position_error;
        uint32_t vertical_position_error;
        uint32_t time_error;
        int16_t horizontal_velocity_error;
        int32_t clock_bias;
        uint32_t clock_bias_error;
        int32_t clock_drift;
        uint32_t clock_drift_error;
        uint32_t distance;
        uint16_t distance_error;
        uint16_t heading_error;
        uint8_t satellites;
        uint8_t hdop;
        uint8_t mode_info;
    };
    enum sirf_protocol_bytes {
        PREAMBLE1 = 0xa0,
        PREAMBLE2 = 0xa2,
        POSTAMBLE1 = 0xb0,
        POSTAMBLE2 = 0xb3,
        MSG_GEONAV = 0x29
    };
    enum sirf_fix_type {
        FIX_3D = 0x6,
        FIX_MASK = 0x7
    };


    // State machine state
    uint8_t         _step;
    uint16_t        _checksum;
    bool            _gather;
    uint16_t        _payload_length;
    uint16_t        _payload_counter;
    uint8_t         _msg_id;

    // Message buffer
    union {
        sirf_geonav nav;
        uint8_t bytes[];
    } _buffer;

    bool        _parse_gps(void);
    void        _accumulate(uint8_t val);
};

#endif // AP_GPS_SIRF_h