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Merge branch 'prefer-global-cpr'

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This commit is contained in:
Oliver Jowett 2014-09-25 17:18:08 +01:00
commit d820ae1afc
3 changed files with 24 additions and 22 deletions

13
mode_s.c
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@ -2062,11 +2062,8 @@ double cprDlonFunction(double lat, int fflag, int surface) {
//
// A few remarks:
// 1) 131072 is 2^17 since CPR latitude and longitude are encoded in 17 bits.
// 2) We assume that we always received the odd packet as last packet for
// simplicity. This may provide a position that is less fresh of a few
// seconds.
//
void decodeCPR(struct aircraft *a, int fflag, int surface) {
int decodeCPR(struct aircraft *a, int fflag, int surface) {
double AirDlat0 = (surface ? 90.0 : 360.0) / 60.0;
double AirDlat1 = (surface ? 90.0 : 360.0) / 59.0;
double lat0 = a->even_cprlat;
@ -2092,7 +2089,8 @@ void decodeCPR(struct aircraft *a, int fflag, int surface) {
surface_rlat = Modes.fUserLat;
surface_rlon = Modes.fUserLon;
} else {
return;
// No local reference, give up
return (-1);
}
rlat0 += floor(surface_rlat / 90.0) * 90.0; // Move from 1st quadrant to our quadrant
rlat1 += floor(surface_rlat / 90.0) * 90.0;
@ -2105,7 +2103,8 @@ void decodeCPR(struct aircraft *a, int fflag, int surface) {
if (rlat0 < -90 || rlat0 > 90 || rlat1 < -90 || rlat1 > 90) return;
// Check that both are in the same latitude zone, or abort.
if (cprNLFunction(rlat0) != cprNLFunction(rlat1)) return;
if (cprNLFunction(rlat0) != cprNLFunction(rlat1))
return (-1);
// Compute ni and the Longitude Index "m"
if (fflag) { // Use odd packet.
@ -2131,6 +2130,8 @@ void decodeCPR(struct aircraft *a, int fflag, int surface) {
a->seenLatLon = a->seen;
a->timestampLatLon = a->timestamp;
a->bFlags |= (MODES_ACFLAGS_LATLON_VALID | MODES_ACFLAGS_LATLON_REL_OK);
return 0;
}
//
//=========================================================================