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Fix NaN in greatcircle calc if positions are identical.

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Bail out early if there's a global CPR decoding error so we don't try
to do range/speed checks on a position of (0,0)
This commit is contained in:
Oliver Jowett 2015-02-18 01:53:47 +00:00
parent bfe2cb0336
commit 44302bb199
1 changed files with 12 additions and 2 deletions
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14
track.c
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@ -120,6 +120,11 @@ static double greatcircle(double lat0, double lon0, double lat1, double lon1)
lon0 = lon0 * M_PI / 180.0;
lat1 = lat1 * M_PI / 180.0;
lon1 = lon1 * M_PI / 180.0;
// avoid NaN
if (fabs(lat0 - lat1) < 0.0001 && fabs(lon0 - lon1) < 0.0001)
return 0.0;
return 6371e3 * acos(sin(lat0) * sin(lat1) + cos(lat0) * cos(lat1) * cos(fabs(lon0 - lon1)));
}
@ -131,6 +136,7 @@ static int speed_check(struct aircraft *a, double lat, double lon, uint64_t now,
double distance;
double range;
int speed;
int inrange;
if (!(a->bFlags & MODES_ACFLAGS_LATLON_VALID))
return 1; // no reference, assume OK
@ -164,14 +170,15 @@ static int speed_check(struct aircraft *a, double lat, double lon, uint64_t now,
// find actual distance
distance = greatcircle(a->lat, a->lon, lat, lon);
inrange = (distance <= range);
#ifdef DEBUG_CPR_CHECKS
if (distance >= range) {
if (!inrange) {
fprintf(stderr, "Speed check failed: %06x: %.3f,%.3f -> %.3f,%.3f in %.1f seconds, max speed %d kt, range %.1fkm, actual %.1fkm\n",
a->addr, a->lat, a->lon, lat, lon, elapsed/1000.0, speed, range/1000.0, distance/1000.0);
}
#endif
return (distance < range);
return inrange;
}
static int doGlobalCPR(struct aircraft *a, int fflag, int surface, uint64_t now, double *lat, double *lon, unsigned *nuc)
@ -211,6 +218,9 @@ static int doGlobalCPR(struct aircraft *a, int fflag, int surface, uint64_t now,
lat, lon);
}
if (result < 0)
return result;
// check max range
if (Modes.maxRange > 0 && (Modes.bUserFlags & MODES_USER_LATLON_VALID)) {
double range = greatcircle(Modes.fUserLat, Modes.fUserLon, *lat, *lon);