Copter: use an enumeration for pre-throw motor state

ArduCopter/Parameters.cpp

@@ -699,7 +699,7 @@ const AP_Param::Info Copter::var_info[] = {
     // @Description: Used by Throw mode. Controls whether motors will run at the speed set by MOT_SPIN_MIN or will be stopped when armed and waiting for the throw.
     // @Values: 0:Stopped,1:Running
     // @User: Standard
-    GSCALAR(throw_motor_start, "THROW_MOT_START", 0),
+    GSCALAR(throw_motor_start, "THROW_MOT_START", (float)ModeThrow::PreThrowMotorState::STOPPED),
 #endif
 
     // @Param: RTL_ALT_TYPE

ArduCopter/Parameters.h

@@ -447,7 +447,7 @@ public:
     AP_Int16        gcs_pid_mask;
 
 #if MODE_THROW_ENABLED == ENABLED
-    AP_Int8         throw_motor_start;
+    AP_Enum<ModeThrow::PreThrowMotorState>         throw_motor_start;
 #endif
 
     AP_Int8         rtl_alt_type;

ArduCopter/mode.h

@@ -1340,6 +1340,11 @@ public:
         Drop = 1
     };
 
+    enum class PreThrowMotorState {
+        STOPPED = 0,
+        RUNNING = 1,
+    };
+
 protected:
 
     const char *name() const override { return "THROW"; }

ArduCopter/mode_throw.cpp

@@ -108,7 +108,7 @@ void ModeThrow::run()
     case Throw_Disarmed:
 
         // prevent motors from rotating before the throw is detected unless enabled by the user
-        if (g.throw_motor_start == 1) {
+        if (g.throw_motor_start == PreThrowMotorState::RUNNING) {
             motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         } else {
             motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::SHUT_DOWN);
@@ -123,7 +123,7 @@ void ModeThrow::run()
     case Throw_Detecting:
 
         // prevent motors from rotating before the throw is detected unless enabled by the user
-        if (g.throw_motor_start == 1) {
+        if (g.throw_motor_start == PreThrowMotorState::RUNNING) {
             motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         } else {
             motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::SHUT_DOWN);