AP_Arming: move checking of fence up

libraries/AP_Arming/AP_Arming.cpp

@@ -23,6 +23,7 @@
 #include <AP_Mission/AP_Mission.h>
 #include <AP_Rally/AP_Rally.h>
 #include <SRV_Channel/SRV_Channel.h>
+#include <AC_Fence/AC_Fence.h>
 
 #if HAL_WITH_UAVCAN
   #include <AP_BoardConfig/AP_BoardConfig_CAN.h>
@@ -696,6 +697,29 @@ bool AP_Arming::can_checks(bool report)
     return true;
 }
 
+
+bool AP_Arming::fence_checks(bool display_failure)
+{
+    const AC_Fence *fence = AP::fence();
+    if (fence == nullptr) {
+        return true;
+    }
+
+    // check fence is ready
+    const char *fail_msg = nullptr;
+    if (fence->pre_arm_check(fail_msg)) {
+        return true;
+    }
+
+    if (fail_msg == nullptr) {
+        check_failed(ARMING_CHECK_NONE, display_failure, "Check fence");
+    } else {
+        check_failed(ARMING_CHECK_NONE, display_failure, "%s", fail_msg);
+    }
+
+    return false;
+}
+
 bool AP_Arming::pre_arm_checks(bool report)
 {
 #if !APM_BUILD_TYPE(APM_BUILD_ArduCopter)

libraries/AP_Arming/AP_Arming.h

@@ -114,6 +114,8 @@ protected:
 
     bool mission_checks(bool report);
 
+    bool fence_checks(bool report);
+
     virtual bool system_checks(bool report);
 
     bool can_checks(bool report);