summaryrefslogtreecommitdiff
path: root/gpsutils.c
blob: 3add68b097ecf41dd734cb7a4666124137364df3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
/* gpsutils.c -- code shared between low-level and high-level interfaces
 *
 * This file is Copyright (c) 2010 by the GPSD project
 * BSD terms apply: see the file COPYING in the distribution root for details.
 */

/* The strptime prototype is not provided unless explicitly requested.
 * We also need to set the value high enough to signal inclusion of
 * newer features (like clock_gettime).  See the POSIX spec for more info:
 * http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_02_01_02 */
#define _XOPEN_SOURCE 600

#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <errno.h>
#include <ctype.h>

#include "gps.h"
#include "libgps.h"

#ifdef USE_QT
#include <QDateTime>
#include <QStringList>
#endif

/*
 * Berkeley implementation of strtod(), inlined to avoid locale problems
 * with the decimal point and stripped down to an atof()-equivalent.
 */

double safe_atof(const char *string)
/* Takes a decimal ASCII floating-point number, optionally
 * preceded by white space.  Must have form "-I.FE-X",
 * where I is the integer part of the mantissa, F is
 * the fractional part of the mantissa, and X is the
 * exponent.  Either of the signs may be "+", "-", or
 * omitted.  Either I or F may be omitted, or both.
 * The decimal point isn't necessary unless F is
 * present.  The "E" may actually be an "e".  E and X
 * may both be omitted (but not just one).
 */
{
    static int maxExponent = 511;   /* Largest possible base 10 exponent.  Any
				     * exponent larger than this will already
				     * produce underflow or overflow, so there's
				     * no need to worry about additional digits.
				     */
    static double powersOf10[] = {  /* Table giving binary powers of 10.  Entry */
	10.,			/* is 10^2^i.  Used to convert decimal */
	100.,			/* exponents into floating-point numbers. */
	1.0e4,
	1.0e8,
	1.0e16,
	1.0e32,
	1.0e64,
	1.0e128,
	1.0e256
    };

    bool sign, expSign = false;
    double fraction, dblExp, *d;
    register const char *p;
    register int c;
    int exp = 0;		/* Exponent read from "EX" field. */
    int fracExp = 0;		/* Exponent that derives from the fractional
				 * part.  Under normal circumstatnces, it is
				 * the negative of the number of digits in F.
				 * However, if I is very long, the last digits
				 * of I get dropped (otherwise a long I with a
				 * large negative exponent could cause an
				 * unnecessary overflow on I alone).  In this
				 * case, fracExp is incremented one for each
				 * dropped digit. */
    int mantSize;		/* Number of digits in mantissa. */
    int decPt;			/* Number of mantissa digits BEFORE decimal
				 * point. */
    const char *pExp;		/* Temporarily holds location of exponent
				 * in string. */

    /*
     * Strip off leading blanks and check for a sign.
     */

    p = string;
    while (isspace((unsigned char) *p)) {
	p += 1;
    }
    if (*p == '-') {
	sign = true;
	p += 1;
    } else {
	if (*p == '+') {
	    p += 1;
	}
	sign = false;
    }

    /*
     * Count the number of digits in the mantissa (including the decimal
     * point), and also locate the decimal point.
     */

    decPt = -1;
    for (mantSize = 0; ; mantSize += 1)
    {
	c = *p;
	if (!isdigit(c)) {
	    if ((c != '.') || (decPt >= 0)) {
		break;
	    }
	    decPt = mantSize;
	}
	p += 1;
    }

    /*
     * Now suck up the digits in the mantissa.  Use two integers to
     * collect 9 digits each (this is faster than using floating-point).
     * If the mantissa has more than 18 digits, ignore the extras, since
     * they can't affect the value anyway.
     */

    pExp  = p;
    p -= mantSize;
    if (decPt < 0) {
	decPt = mantSize;
    } else {
	mantSize -= 1;			/* One of the digits was the point. */
    }
    if (mantSize > 18) {
	fracExp = decPt - 18;
	mantSize = 18;
    } else {
	fracExp = decPt - mantSize;
    }
    if (mantSize == 0) {
	fraction = 0.0;
	//p = string;
	goto done;
    } else {
	int frac1, frac2;
	frac1 = 0;
	for ( ; mantSize > 9; mantSize -= 1)
	{
	    c = *p;
	    p += 1;
	    if (c == '.') {
		c = *p;
		p += 1;
	    }
	    frac1 = 10*frac1 + (c - '0');
	}
	frac2 = 0;
	for (; mantSize > 0; mantSize -= 1)
	{
	    c = *p;
	    p += 1;
	    if (c == '.') {
		c = *p;
		p += 1;
	    }
	    frac2 = 10*frac2 + (c - '0');
	}
	fraction = (1.0e9 * frac1) + frac2;
    }

    /*
     * Skim off the exponent.
     */

    p = pExp;
    if ((*p == 'E') || (*p == 'e')) {
	p += 1;
	if (*p == '-') {
	    expSign = true;
	    p += 1;
	} else {
	    if (*p == '+') {
		p += 1;
	    }
	    expSign = false;
	}
	while (isdigit((unsigned char) *p)) {
	    exp = exp * 10 + (*p - '0');
	    p += 1;
	}
    }
    if (expSign) {
	exp = fracExp - exp;
    } else {
	exp = fracExp + exp;
    }

    /*
     * Generate a floating-point number that represents the exponent.
     * Do this by processing the exponent one bit at a time to combine
     * many powers of 2 of 10. Then combine the exponent with the
     * fraction.
     */

    if (exp < 0) {
	expSign = true;
	exp = -exp;
    } else {
	expSign = false;
    }
    if (exp > maxExponent) {
	exp = maxExponent;
	errno = ERANGE;
    }
    dblExp = 1.0;
    for (d = powersOf10; exp != 0; exp >>= 1, d += 1) {
	if (exp & 01) {
	    dblExp *= *d;
	}
    }
    if (expSign) {
	fraction /= dblExp;
    } else {
	fraction *= dblExp;
    }

done:
    if (sign) {
	return -fraction;
    }
    return fraction;
}

#define MONTHSPERYEAR	12	/* months per calendar year */

void gps_clear_fix(struct gps_fix_t *fixp)
/* stuff a fix structure with recognizable out-of-band values */
{
    fixp->time = NAN;
    fixp->mode = MODE_NOT_SEEN;
    fixp->latitude = fixp->longitude = NAN;
    fixp->track = NAN;
    fixp->speed = NAN;
    fixp->climb = NAN;
    fixp->altitude = NAN;
    fixp->ept = NAN;
    fixp->epx = NAN;
    fixp->epy = NAN;
    fixp->epv = NAN;
    fixp->epd = NAN;
    fixp->eps = NAN;
    fixp->epc = NAN;
}

void gps_clear_dop( struct dop_t *dop)
{
    dop->xdop = dop->ydop = dop->vdop = dop->tdop = dop->hdop = dop->pdop =
        dop->gdop = NAN;
}

void gps_merge_fix(struct gps_fix_t *to,
		   gps_mask_t transfer,
		   struct gps_fix_t *from)
/* merge new data into an old fix */
{
    if ((NULL == to) || (NULL == from))
	return;
    if ((transfer & TIME_SET) != 0)
	to->time = from->time;
    if ((transfer & LATLON_SET) != 0) {
	to->latitude = from->latitude;
	to->longitude = from->longitude;
    }
    if ((transfer & MODE_SET) != 0)
	to->mode = from->mode;
    if ((transfer & ALTITUDE_SET) != 0)
	to->altitude = from->altitude;
    if ((transfer & TRACK_SET) != 0)
	to->track = from->track;
    if ((transfer & SPEED_SET) != 0)
	to->speed = from->speed;
    if ((transfer & CLIMB_SET) != 0)
	to->climb = from->climb;
    if ((transfer & TIMERR_SET) != 0)
	to->ept = from->ept;
    if ((transfer & HERR_SET) != 0) {
	to->epx = from->epx;
	to->epy = from->epy;
    }
    if ((transfer & VERR_SET) != 0)
	to->epv = from->epv;
    if ((transfer & SPEEDERR_SET) != 0)
	to->eps = from->eps;
}

/* NOTE: timestamp_t is a double, so this is only precise to
 * near microSec.  Do not use near PPS which is nanoSec precise */
timestamp_t timestamp(void)
{
     struct timespec ts;
     (void)clock_gettime(CLOCK_REALTIME, &ts);
     return (timestamp_t)(ts.tv_sec + ts.tv_nsec * 1e-9);
}

time_t mkgmtime(register struct tm * t)
/* struct tm to seconds since Unix epoch */
{
    register int year;
    register time_t result;
    static const int cumdays[MONTHSPERYEAR] =
	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

    year = 1900 + t->tm_year + t->tm_mon / MONTHSPERYEAR;
    result = (year - 1970) * 365 + cumdays[t->tm_mon % MONTHSPERYEAR];
    result += (year - 1968) / 4;
    result -= (year - 1900) / 100;
    result += (year - 1600) / 400;
    if ((year % 4) == 0 && ((year % 100) != 0 || (year % 400) == 0) &&
	(t->tm_mon % MONTHSPERYEAR) < 2)
	result--;
    result += t->tm_mday - 1;
    result *= 24;
    result += t->tm_hour;
    result *= 60;
    result += t->tm_min;
    result *= 60;
    result += t->tm_sec;
    if (t->tm_isdst == 1)
	result -= 3600;
    return (result);
}

timestamp_t iso8601_to_unix(char *isotime)
/* ISO8601 UTC to Unix UTC, no leapsecond correction. */
{
#ifndef __clang_analyzer__
#ifndef USE_QT
    char *dp = NULL;
    double usec;
    struct tm tm;
    memset(&tm,0,sizeof(tm));

    dp = strptime(isotime, "%Y-%m-%dT%H:%M:%S", &tm);
    if (dp != NULL && *dp == '.')
	usec = strtod(dp, NULL);
    else
	usec = 0;
    /*
     * It would be nice if we could say mktime(&tm) - timezone + usec instead,
     * but timezone is not available at all on some BSDs. Besides, when working
     * with historical dates the value of timezone after an ordinary tzset(3)
     * can be wrong; you have to do a redirect through the IANA historical
     * timezone database to get it right.
     */
    return (timestamp_t)mkgmtime(&tm) + usec;
#else
    double usec = 0;

    QString t(isotime);
    QDateTime d = QDateTime::fromString(isotime, Qt::ISODate);
    QStringList sl = t.split(".");
    if (sl.size() > 1)
	usec = sl[1].toInt() / pow(10., (double)sl[1].size());
    return (timestamp_t)(d.toTime_t() + usec);
#endif
#endif /* __clang_analyzer__ */
}

/* *INDENT-OFF* */
char *unix_to_iso8601(timestamp_t fixtime, /*@ out @*/
				     char isotime[], size_t len)
/* Unix UTC time to ISO8601, no timezone adjustment */
/* example: 2007-12-11T23:38:51.033Z */
{
    struct tm when;
    double integral, fractional;
    time_t intfixtime;
    char timestr[30];
    char fractstr[10];

    fractional = modf(fixtime, &integral);
    intfixtime = (time_t) integral;
    (void)gmtime_r(&intfixtime, &when);

    (void)strftime(timestr, sizeof(timestr), "%Y-%m-%dT%H:%M:%S", &when);
    /*
     * Do not mess casually with the number of decimal digits in the
     * format!  Most GPSes report over serial links at 0.01s or 0.001s
     * precision.
     */
    (void)snprintf(fractstr, sizeof(fractstr), "%.3f", fractional);
    /* add fractional part, ignore leading 0; "0.2" -> ".2" */
    (void)snprintf(isotime, len, "%s%sZ",timestr, strchr(fractstr,'.'));
    return isotime;
}
/* *INDENT-ON* */

#define Deg2Rad(n)	((n) * DEG_2_RAD)

/* Distance in meters between two points specified in degrees, optionally
with initial and final bearings. */
double earth_distance_and_bearings(double lat1, double lon1, double lat2, double lon2, double *ib, double *fb)
{
    /*
     * this is a translation of the javascript implementation of the
     * Vincenty distance formula by Chris Veness. See
     * http://www.movable-type.co.uk/scripts/latlong-vincenty.html
     */
    double a, b, f;		// WGS-84 ellipsoid params
    double L, L_P, U1, U2, s_U1, c_U1, s_U2, c_U2;
    double uSq, A, B, d_S, lambda;
    // cppcheck-suppress variableScope
    double s_L, c_L, s_A, C;
    double c_S, S, s_S, c_SqA, c_2SM;
    int i = 100;

    a = WGS84A;
    b = WGS84B;
    f = 1 / WGS84F;
    L = Deg2Rad(lon2 - lon1);
    U1 = atan((1 - f) * tan(Deg2Rad(lat1)));
    U2 = atan((1 - f) * tan(Deg2Rad(lat2)));
    s_U1 = sin(U1);
    c_U1 = cos(U1);
    s_U2 = sin(U2);
    c_U2 = cos(U2);
    lambda = L;

    do {
	s_L = sin(lambda);
	c_L = cos(lambda);
	s_S = sqrt((c_U2 * s_L) * (c_U2 * s_L) +
		   (c_U1 * s_U2 - s_U1 * c_U2 * c_L) *
		   (c_U1 * s_U2 - s_U1 * c_U2 * c_L));

	if (s_S == 0)
	    return 0;

	c_S = s_U1 * s_U2 + c_U1 * c_U2 * c_L;
	S = atan2(s_S, c_S);
	s_A = c_U1 * c_U2 * s_L / s_S;
	c_SqA = 1 - s_A * s_A;
	c_2SM = c_S - 2 * s_U1 * s_U2 / c_SqA;

	if (isnan(c_2SM))
	    c_2SM = 0;

	C = f / 16 * c_SqA * (4 + f * (4 - 3 * c_SqA));
	L_P = lambda;
	lambda = L + (1 - C) * f * s_A *
	    (S + C * s_S * (c_2SM + C * c_S * (2 * c_2SM * c_2SM - 1)));
    } while ((fabs(lambda - L_P) > 1.0e-12) && (--i > 0));

    if (i == 0)
	return NAN;		// formula failed to converge

    uSq = c_SqA * ((a * a) - (b * b)) / (b * b);
    A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)));
    B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)));
    d_S = B * s_S * (c_2SM + B / 4 *
		     (c_S * (-1 + 2 * c_2SM * c_2SM) - B / 6 * c_2SM *
		      (-3 + 4 * s_S * s_S) * (-3 + 4 * c_2SM * c_2SM)));

    if (ib != NULL)
	*ib = atan2(c_U2 * sin(lambda), c_U1 * s_U2 - s_U1 * c_U2 * cos(lambda));
    if (fb != NULL)
	*fb = atan2(c_U1 * sin(lambda), c_U1 * s_U2 * cos(lambda) - s_U1 * c_U2);

    return (WGS84B * A * (S - d_S));
}

/* Distance in meters between two points specified in degrees. */
double earth_distance(double lat1, double lon1, double lat2, double lon2)
{
	return earth_distance_and_bearings(lat1, lon1, lat2, lon2, NULL, NULL);
}

/* end */