From 0922b82d4233cf105d0a825a1174e572f9d75798 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Thu, 20 Sep 2012 07:42:35 +1000
Subject: [PATCH] AP_Param: added find_by_index()

---
 libraries/AP_Common/AP_Param.cpp | 16 ++++++++++++++++
 libraries/AP_Common/AP_Param.h   |  9 +++++++++
 2 files changed, 25 insertions(+)

diff --git a/libraries/AP_Common/AP_Param.cpp b/libraries/AP_Common/AP_Param.cpp
index 8eae231eab..7e9a0d0827 100644
--- a/libraries/AP_Common/AP_Param.cpp
+++ b/libraries/AP_Common/AP_Param.cpp
@@ -579,6 +579,22 @@ AP_Param::find(const char *name, enum ap_var_type *ptype)
     return NULL;
 }
 
+// Find a variable by index. Note that this is quite slow.
+//
+AP_Param *
+AP_Param::find_by_index(uint16_t idx, enum ap_var_type *ptype)
+{
+    ParamToken token;
+    AP_Param *ap;
+    uint16_t count=0;
+    for (ap=AP_Param::first(&token, ptype);
+         ap && count < idx;
+         ap=AP_Param::next_scalar(&token, ptype)) {
+        count++;
+    }
+    return ap;    
+}
+
 // Save the variable to EEPROM, if supported
 //
 bool AP_Param::save(void)
diff --git a/libraries/AP_Common/AP_Param.h b/libraries/AP_Common/AP_Param.h
index c06d9a03dc..9b1379e415 100644
--- a/libraries/AP_Common/AP_Param.h
+++ b/libraries/AP_Common/AP_Param.h
@@ -132,6 +132,15 @@ public:
     ///
     static AP_Param * find(const char *name, enum ap_var_type *ptype);
 
+    /// Find a variable by index.
+    ///
+    ///
+    /// @param  idx             The index of the variable
+    /// @return                 A pointer to the variable, or NULL if
+    ///                         it does not exist.
+    ///
+    static AP_Param * find_by_index(uint16_t idx, enum ap_var_type *ptype);
+
     /// Save the current value of the variable to EEPROM.
     ///
     /// @return                True if the variable was saved successfully.