minmea/minmea.h

189 lines
4.7 KiB
C

/*
* Copyright © 2014 Kosma Moczek <kosma@cloudyourcar.com>
* This program is free software. It comes without any warranty, to the extent
* permitted by applicable law. You can redistribute it and/or modify it under
* the terms of the Do What The Fuck You Want To Public License, Version 2, as
* published by Sam Hocevar. See the COPYING file for more details.
*/
#ifndef MINMEA_H
#define MINMEA_H
#ifdef __cplusplus
extern "C" {
#endif
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <errno.h>
#include <time.h>
#include <math.h>
#include <sys/time.h>
#define MINMEA_MAX_LENGTH 80
enum minmea_sentence_id {
MINMEA_INVALID = -1,
MINMEA_UNKNOWN = 0,
MINMEA_SENTENCE_RMC,
MINMEA_SENTENCE_GGA,
MINMEA_SENTENCE_GSA,
MINMEA_SENTENCE_GST
};
struct minmea_date {
int day;
int month;
int year;
};
struct minmea_time {
int hours;
int minutes;
int seconds;
int microseconds;
};
struct minmea_sentence_rmc {
struct minmea_time time;
bool valid;
int latitude, latitude_scale;
int longitude, longitude_scale;
int speed, speed_scale;
int course, course_scale;
struct minmea_date date;
int variation, variation_scale;
};
struct minmea_sentence_gga {
struct minmea_time time;
int latitude, latitude_scale;
int longitude, longitude_scale;
int fix_quality;
int satellites_tracked;
int hdop, hdop_scale;
int altitude, altitude_scale; char altitude_units;
int height, height_scale; char height_units;
int dgps_age;
};
struct minmea_sentence_gst {
struct minmea_time time;
int RMS_deviation, RMS_deviation_scale;
int semi_major_sd, semi_major_sd_scale;
int semi_minor_sd, semi_minor_sd_scale;
int semi_major_orientation, semi_major_orientation_scale;
int lattitude_error_deviation, lattitude_error_deviation_scale;
int longitude_error_deviation, longitude_error_deviation_scale;
int altitude_error_deviation, altitude_error_deviation_scale;
};
enum minmea_gsa_mode {
MINMEA_GPGSA_MODE_AUTO = 'A',
MINMEA_GPGSA_MODE_FORCED = 'M',
};
enum minmea_gsa_fix_type {
MINMEA_GPGSA_FIX_NONE = 1,
MINMEA_GPGSA_FIX_2D = 2,
MINMEA_GPGSA_FIX_3D = 3,
};
struct minmea_sentence_gsa {
char mode;
int fix_type;
int sats[12];
int pdop, pdop_scale;
int hdop, hdop_scale;
int vdop, vdop_scale;
};
/**
* Check sentence validity and checksum. Returns true for valid sentences.
*/
bool minmea_check(const char *sentence);
/**
* Determine talker identifier.
*/
bool minmea_talker_id(char talker[3], const char *sentence);
/**
* Determine sentence identifier.
*/
enum minmea_sentence_id minmea_sentence_id(const char *sentence);
/**
* Scanf-like processor for NMEA sentences. Supports the following formats:
* c - single character (char *)
* d - direction, returned as 1/-1, default 0 (int *)
* f - fractional, returned as value + scale (int *, int *)
* i - decimal, default zero (int *)
* s - string (char *)
* t - talker identifier and type (char *)
* T - date/time stamp (int *, int *, int *)
* Returns true on success. See library source code for details.
*/
bool minmea_scan(const char *sentence, const char *format, ...);
/*
* Parse a specific type of sentence. Return true on success.
*/
bool minmea_parse_rmc(struct minmea_sentence_rmc *frame, const char *sentence);
bool minmea_parse_gga(struct minmea_sentence_gga *frame, const char *sentence);
bool minmea_parse_gsa(struct minmea_sentence_gsa *frame, const char *sentence);
bool minmea_parse_gst(struct minmea_sentence_gst *frame, const char *sentence);
/**
* Convert GPS UTC date/time representation to a UNIX timestamp.
*/
int minmea_gettimeofday(struct timeval *tv, const struct minmea_date *date, const struct minmea_time *time);
/**
* Rescale a fixed-point value to a different scale. Rounds towards zero.
*/
static inline int minmea_rescale(int value, int from, int to)
{
if (from == 0)
return 0;
if (from == to)
return value;
if (from > to)
return (value + ((value > 0) - (value < 0)) * from/to/2) / (from/to);
else
return value * (to/from);
}
/**
* Convert a fixed-point value to a floating-point value.
* Returns NaN for "unknown" values.
*/
static inline float minmea_float(int value, int scale)
{
if (scale == 0)
return NAN;
return (float) value / (float) scale;
}
/**
* Convert a raw coordinate to a floating point DD.DDD... value.
* Returns NaN for "unknown" values.
*/
static inline float minmea_coord(int value, int scale)
{
if (scale == 0)
return NAN;
int degrees = value / (scale * 100);
int minutes = value % (scale * 100);
return (float) degrees + (float) minutes / (60 * scale);
}
#ifdef __cplusplus
}
#endif
#endif /* MINMEA_H */
/* vim: set ts=4 sw=4 et: */