From 7aa98d55eb6c678081f8050bd23875a6af490f29 Mon Sep 17 00:00:00 2001
From: Andy Piper <github@andypiper.com>
Date: Sun, 10 May 2020 15:04:03 +0100
Subject: [PATCH] AP_Param: expose the stable key for use by AP_OSD add support
 for finding parameters by name and returning the token

---
 libraries/AP_Param/AP_Param.cpp | 20 ++++++++++++++++++++
 libraries/AP_Param/AP_Param.h   |  6 ++++++
 2 files changed, 26 insertions(+)

diff --git a/libraries/AP_Param/AP_Param.cpp b/libraries/AP_Param/AP_Param.cpp
index ca0de8372a..933b026106 100644
--- a/libraries/AP_Param/AP_Param.cpp
+++ b/libraries/AP_Param/AP_Param.cpp
@@ -909,6 +909,26 @@ AP_Param::find_by_index(uint16_t idx, enum ap_var_type *ptype, ParamToken *token
     return ap;    
 }
 
+// by-name equivalent of find_by_index()
+AP_Param* AP_Param::find_by_name(const char* name, enum ap_var_type *ptype, ParamToken *token)
+{
+    AP_Param *ap;
+    uint16_t count = 0;
+    for (ap = AP_Param::first(token, ptype);
+         ap && *ptype != AP_PARAM_GROUP && *ptype != AP_PARAM_NONE;
+         ap = AP_Param::next_scalar(token, ptype)) {
+        int32_t ret = strncasecmp(name, _var_info[token->key].name, AP_MAX_NAME_SIZE);
+        if (ret >= 0) {
+            char buf[AP_MAX_NAME_SIZE];
+            ap->copy_name_token(*token, buf, AP_MAX_NAME_SIZE);
+            if (strncasecmp(name, buf, AP_MAX_NAME_SIZE) == 0) {
+                break;
+            }
+        }
+        count++;
+    }
+    return ap;
+}
 
 /*
   Find a variable by pointer, returning key. This is used for loading pointer variables
diff --git a/libraries/AP_Param/AP_Param.h b/libraries/AP_Param/AP_Param.h
index 3d42ac1345..a477d91e0e 100644
--- a/libraries/AP_Param/AP_Param.h
+++ b/libraries/AP_Param/AP_Param.h
@@ -314,6 +314,9 @@ public:
     ///
     static AP_Param * find_by_index(uint16_t idx, enum ap_var_type *ptype, ParamToken *token);
 
+    // by-name equivalent of find_by_index()
+    static AP_Param* find_by_name(const char* name, enum ap_var_type *ptype, ParamToken *token);
+
     /// Find a variable by pointer
     ///
     ///
@@ -474,6 +477,9 @@ public:
 
     // return true if the parameter is read-only
     bool is_read_only(void) const;
+
+    // return the persistent top level key for the ParamToken key
+    static uint16_t get_persistent_key(uint16_t key) { return _var_info[key].key; }
     
     // count of parameters in tree
     static uint16_t count_parameters(void);