AP_Common: remove packed nature of Location, move flags out of union

This saves ~2.5kB on fmuv3

libraries/AP_Common/AP_Common.cpp

@@ -36,3 +36,6 @@ bool is_bounded_int32(int32_t value, int32_t lower_bound, int32_t upper_bound)
     return false;
 
 }
+
+// make sure we know what size the Location object is:
+assert_storage_size<Location, 16> _assert_storage_size_Location;

libraries/AP_Common/AP_Common.h

@@ -129,27 +129,17 @@ template<typename s, int t> struct assert_storage_size {
 
 //@{
 
-struct PACKED Location_Option_Flags {
+struct Location {
     uint8_t relative_alt : 1;           // 1 if altitude is relative to home
-    uint8_t unused1      : 1;           // unused flag (defined so that loiter_ccw uses the correct bit)
     uint8_t loiter_ccw   : 1;           // 0 if clockwise, 1 if counter clockwise
     uint8_t terrain_alt  : 1;           // this altitude is above terrain
     uint8_t origin_alt   : 1;           // this altitude is above ekf origin
     uint8_t loiter_xtrack : 1;          // 0 to crosstrack from center of waypoint, 1 to crosstrack from tangent exit location
-};
 
-struct PACKED Location {
+    // note that mission storage only stores 24 bits of altitude (~ +/- 83km)
-    union {
+    int32_t alt;
-        Location_Option_Flags flags;                    ///< options bitmask (1<<0 = relative altitude)
+    int32_t lat;
-        uint8_t options;                                /// allows writing all flags to eeprom as one byte
+    int32_t lng;
-    };
-    // by making alt 24 bit we can make p1 in a command 16 bit,
-    // allowing an accurate angle in centi-degrees. This keeps the
-    // storage cost per mission item at 15 bytes, and allows mission
-    // altitudes of up to +/- 83km
-    int32_t alt:24;                                     ///< param 2 - Altitude in centimeters (meters * 100) see LOCATION_ALT_MAX_M
-    int32_t lat;                                        ///< param 3 - Latitude * 10**7
-    int32_t lng;                                        ///< param 4 - Longitude * 10**7
 };
 
 //@}

libraries/AP_Common/Location.cpp

@@ -17,11 +17,22 @@ Location_Class::Location_Class()
     zero();
 }
 
+const Location_Class definitely_zero{};
+bool Location_Class::is_zero(void) const
+{
+    return !memcmp(this, &definitely_zero, sizeof(*this));
+}
+
+void Location_Class::zero(void)
+{
+    memset(this, 0, sizeof(*this));
+}
+
 Location_Class::Location_Class(int32_t latitude, int32_t longitude, int32_t alt_in_cm, ALT_FRAME frame)
 {
+    zero();
     lat = latitude;
     lng = longitude;
-    options = 0;
     set_alt_cm(alt_in_cm, frame);
 }
 
@@ -30,7 +41,11 @@ Location_Class::Location_Class(const Location& loc)
     lat = loc.lat;
     lng = loc.lng;
     alt = loc.alt;
-    options = loc.options;
+    relative_alt = loc.relative_alt;
+    loiter_ccw = loc.loiter_ccw;
+    terrain_alt = loc.terrain_alt;
+    origin_alt = loc.origin_alt;
+    loiter_xtrack = loc.loiter_xtrack;
 }
 
 Location_Class::Location_Class(const Vector3f &ekf_offset_neu)
@@ -52,31 +67,35 @@ Location_Class& Location_Class::operator=(const struct Location &loc)
     lat = loc.lat;
     lng = loc.lng;
     alt = loc.alt;
-    options = loc.options;
+    relative_alt = loc.relative_alt;
+    loiter_ccw = loc.loiter_ccw;
+    terrain_alt = loc.terrain_alt;
+    origin_alt = loc.origin_alt;
+    loiter_xtrack = loc.loiter_xtrack;
     return *this;
 }
 
 void Location_Class::set_alt_cm(int32_t alt_cm, ALT_FRAME frame)
 {
     alt = alt_cm;
-    flags.relative_alt = false;
+    relative_alt = false;
-    flags.terrain_alt = false;
+    terrain_alt = false;
-    flags.origin_alt = false;
+    origin_alt = false;
     switch (frame) {
         case ALT_FRAME_ABSOLUTE:
             // do nothing
             break;
         case ALT_FRAME_ABOVE_HOME:
-            flags.relative_alt = true;
+            relative_alt = true;
             break;
         case ALT_FRAME_ABOVE_ORIGIN:
-            flags.origin_alt = true;
+            origin_alt = true;
             break;
         case ALT_FRAME_ABOVE_TERRAIN:
             // we mark it as a relative altitude, as it doesn't have
             // home alt added
-            flags.relative_alt = true;
+            relative_alt = true;
-            flags.terrain_alt = true;
+            terrain_alt = true;
             break;
     }
 }
@@ -95,13 +114,13 @@ bool Location_Class::change_alt_frame(ALT_FRAME desired_frame)
 // get altitude frame
 Location_Class::ALT_FRAME Location_Class::get_alt_frame() const
 {
-    if (flags.terrain_alt) {
+    if (terrain_alt) {
         return ALT_FRAME_ABOVE_TERRAIN;
     }
-    if (flags.origin_alt) {
+    if (origin_alt) {
         return ALT_FRAME_ABOVE_ORIGIN;
     }
-    if (flags.relative_alt) {
+    if (relative_alt) {
         return ALT_FRAME_ABOVE_HOME;
     }
     return ALT_FRAME_ABSOLUTE;

libraries/AP_Common/Location.h

@@ -66,9 +66,9 @@ public:
     // extrapolate latitude/longitude given distances (in meters) north and east
     void offset(float ofs_north, float ofs_east);
 
-    bool is_zero(void) { return (lat == 0 && lng == 0 && alt == 0 && options == 0); }
+    bool is_zero(void) const;
 
-    void zero(void) { lat = lng = alt = 0; options = 0; }
+    void zero(void);
 
 private:
     static AP_Terrain *_terrain;