AP_AHRS: move AOA/SSA to AP_AHRS, don't recalc on fetch

libraries/AP_AHRS/AP_AHRS.cpp

@@ -320,6 +320,9 @@ void AP_AHRS::update(bool skip_ins_update)
         _view->update(skip_ins_update);
     }
 
+    // update AOA and SSA
+    update_AOA_SSA();
+
 #if HAL_NMEA_OUTPUT_ENABLED
     // update NMEA output
     if (_nmea_out != nullptr) {

libraries/AP_AHRS/AP_AHRS.h

@@ -324,6 +324,18 @@ public:
     // create a view
     AP_AHRS_View *create_view(enum Rotation rotation, float pitch_trim_deg=0);
 
+    // write AOA and SSA information to dataflash logs:
+    void Write_AOA_SSA(void) const;
+
+    // update AOA and SSA values
+    virtual void update_AOA_SSA(void);
+
+    // return AOA
+    float getAOA(void) const { return _AOA; }
+
+    // return SSA
+    float getSSA(void) const { return _SSA; }
+
 protected:
     // optional view class
     AP_AHRS_View *_view;

libraries/AP_AHRS/AP_AHRS_Backend.cpp

@@ -248,7 +248,7 @@ AP_AHRS_View *AP_AHRS::create_view(enum Rotation rotation, float pitch_trim_deg)
  * "ANGLE OF ATTACK AND SIDESLIP ESTIMATION USING AN INERTIAL REFERENCE PLATFORM" by
  * JOSEPH E. ZEIS, JR., CAPTAIN, USAF
  */
-void AP_AHRS_Backend::update_AOA_SSA(void)
+void AP_AHRS::update_AOA_SSA(void)
 {
 #if APM_BUILD_TYPE(APM_BUILD_ArduPlane)
     const uint32_t now = AP_HAL::millis();
@@ -294,20 +294,6 @@ void AP_AHRS_Backend::update_AOA_SSA(void)
 #endif
 }
 
-// return current AOA
-float AP_AHRS_Backend::getAOA(void)
-{
-    update_AOA_SSA();
-    return _AOA;
-}
-
-// return calculated SSA
-float AP_AHRS_Backend::getSSA(void)
-{
-    update_AOA_SSA();
-    return _SSA;
-}
-
 // rotate a 2D vector from earth frame to body frame
 Vector2f AP_AHRS_Backend::earth_to_body2D(const Vector2f &ef) const
 {

libraries/AP_AHRS/AP_AHRS_Backend.h

@@ -514,12 +514,6 @@ public:
         AP::ins().get_delta_velocity(ret, dt);
     }
 
-    // return calculated AOA
-    float getAOA(void);
-
-    // return calculated SSA
-    float getSSA(void);
-
     // rotate a 2D vector from earth frame to body frame
     // in result, x is forward, y is right
     Vector2f earth_to_body2D(const Vector2f &ef_vector) const;
@@ -537,8 +531,6 @@ public:
     Vector3f earth_to_body(const Vector3f &v) const {
         return get_rotation_body_to_ned().mul_transpose(v);
     }
-    
-    virtual void update_AOA_SSA(void);
 
     // get_hgt_ctrl_limit - get maximum height to be observed by the
     // control loops in meters and a validity flag.  It will return
@@ -571,7 +563,6 @@ public:
 
     // Logging to disk functions
     void Write_AHRS2(void) const;
-    void Write_AOA_SSA(void);  // should be const? but it calls update functions
     void Write_Attitude(const Vector3f &targets) const;
     void Write_Origin(uint8_t origin_type, const Location &loc) const; 
     void Write_POS(void) const;

libraries/AP_AHRS/AP_AHRS_DCM.cpp

@@ -112,9 +112,6 @@ AP_AHRS_DCM::update(bool skip_ins_update)
     // update trig values including _cos_roll, cos_pitch
     update_trig();
 
-    // update AOA and SSA
-    update_AOA_SSA();
-
     backup_attitude();
 
     // update takeoff/touchdown flags

libraries/AP_AHRS/AP_AHRS_Logging.cpp

@@ -32,7 +32,7 @@ void AP_AHRS_Backend::Write_AHRS2() const
 }
 
 // Write AOA and SSA
-void AP_AHRS_Backend::Write_AOA_SSA(void)
+void AP_AHRS::Write_AOA_SSA(void) const
 {
     const struct log_AOA_SSA aoa_ssa{
         LOG_PACKET_HEADER_INIT(LOG_AOA_SSA_MSG),