altoslib: Don't smash existing GPS pad alt after boost

Leave the existing GPS pad altitude value in place after boost by
checking to see if it was ever computed before resetting it to the
barometric pad altitude. This makes GPS height values relative to the pad.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/altoslib/AltosState.java b/altoslib/AltosState.java
index 218c598ab5d80d6a4e264b86a1a9d25209b5f933..4f59c840c4f6d02acc8e862a27578b9ed4534c0a 100644 (file)
--- a/altoslib/AltosState.java
+++ b/altoslib/AltosState.java
@@ -200,10 +200,10 @@ public class AltosState {
                                }
                                ngps++;
                        }
-               } else
-                       pad_alt = ground_altitude;
-
-               data.new_gps = false;
+               } else {
+                       if (ngps == 0)
+                               pad_alt = ground_altitude;
+               }
 
                gps_waiting = MIN_PAD_SAMPLES - npad;
                if (gps_waiting < 0)