From d0d6040b3e0c01e746060dcc410bfafaef8ac56f Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Thu, 17 Aug 2017 17:23:36 +1000
Subject: [PATCH] AP_Param: use wider range of sentinal values

this copes better with power off while writing parameters
---
 libraries/AP_Param/AP_Param.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libraries/AP_Param/AP_Param.cpp b/libraries/AP_Param/AP_Param.cpp
index 1d1d5e207f..c3aea9b3aa 100644
--- a/libraries/AP_Param/AP_Param.cpp
+++ b/libraries/AP_Param/AP_Param.cpp
@@ -649,6 +649,13 @@ bool AP_Param::is_sentinal(const Param_header &phdr)
         phdr.group_element == _sentinal_group) {
         return true;
     }
+    // also check for 0xFFFFFFFF and 0x00000000, which are the fill
+    // values for storage. These can appear if power off occurs while
+    // writing data
+    uint32_t v = *(uint32_t *)&phdr;
+    if (v == 0 || v == 0xFFFFFFFF) {
+        return true;
+    }
     return false;
 }