From f30c72188659ba5bc640154118c832616e7fa01a Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Sun, 19 Feb 2012 16:57:49 +1100
Subject: [PATCH] AP_Param: added ParamToken type for variable list traversal

---
 libraries/AP_Common/AP_Param.cpp | 23 +++++++++++++----------
 libraries/AP_Common/AP_Param.h   | 14 ++++++++++----
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/libraries/AP_Common/AP_Param.cpp b/libraries/AP_Common/AP_Param.cpp
index 17c2c28ada..7d07f227da 100644
--- a/libraries/AP_Common/AP_Param.cpp
+++ b/libraries/AP_Common/AP_Param.cpp
@@ -575,9 +575,10 @@ bool AP_Param::load_all(void)
 
 
 // return the first variable in _var_info
-AP_Param *AP_Param::first(uint16_t *token, enum ap_var_type *ptype)
+AP_Param *AP_Param::first(ParamToken *token, enum ap_var_type *ptype)
 {
-    *token = 0;
+    token->key = 0;
+    token->group_element = 0;
     if (_num_vars == 0) {
         return NULL;
     }
@@ -593,7 +594,7 @@ AP_Param *AP_Param::next_group(uint8_t vindex, const struct GroupInfo *group_inf
                                bool *found_current,
                                uint8_t group_base,
                                uint8_t group_shift,
-                               uint16_t *token,
+                               ParamToken *token,
                                enum ap_var_type *ptype)
 {
     uint8_t type;
@@ -612,13 +613,14 @@ AP_Param *AP_Param::next_group(uint8_t vindex, const struct GroupInfo *group_inf
         } else {
             if (*found_current) {
                 // got a new one
-                (*token) = ((uint16_t)GROUP_ID(group_info, group_base, i, group_shift)<<8) | vindex;
+                token->key = vindex;
+                token->group_element = GROUP_ID(group_info, group_base, i, group_shift);
                 if (ptype != NULL) {
                     *ptype = (enum ap_var_type)type;
                 }
                 return (AP_Param*)(PGM_POINTER(&_var_info[vindex].ptr) + PGM_UINT16(&group_info[i].offset));
             }
-            if (GROUP_ID(group_info, group_base, i, group_shift) == (uint8_t)((*token)>>8)) {
+            if (GROUP_ID(group_info, group_base, i, group_shift) == token->group_element) {
                 *found_current = true;
             }
         }
@@ -628,9 +630,9 @@ AP_Param *AP_Param::next_group(uint8_t vindex, const struct GroupInfo *group_inf
 
 /// Returns the next variable in _var_info, recursing into groups
 /// as needed
-AP_Param *AP_Param::next(uint16_t *token, enum ap_var_type *ptype)
+AP_Param *AP_Param::next(ParamToken *token, enum ap_var_type *ptype)
 {
-    uint8_t i = (*token)&0xFF;
+    uint8_t i = token->key;
     bool found_current = false;
     if (i >= _num_vars) {
         // illegal token
@@ -651,7 +653,8 @@ AP_Param *AP_Param::next(uint16_t *token, enum ap_var_type *ptype)
             }
         } else {
             // found the next one
-            (*token) = i;
+            token->key = i;
+            token->group_element = 0;
             if (ptype != NULL) {
                 *ptype = (enum ap_var_type)type;
             }
@@ -663,7 +666,7 @@ AP_Param *AP_Param::next(uint16_t *token, enum ap_var_type *ptype)
 
 /// Returns the next scalar in _var_info, recursing into groups
 /// as needed
-AP_Param *AP_Param::next_scalar(uint16_t *token, enum ap_var_type *ptype)
+AP_Param *AP_Param::next_scalar(ParamToken *token, enum ap_var_type *ptype)
 {
     AP_Param *ap;
     enum ap_var_type type;
@@ -696,7 +699,7 @@ float AP_Param::cast_to_float(enum ap_var_type type)
 // print the value of all variables
 void AP_Param::show_all(void)
 {
-    uint16_t token;
+    ParamToken token;
     AP_Param *ap;
     enum ap_var_type type;
 
diff --git a/libraries/AP_Common/AP_Param.h b/libraries/AP_Common/AP_Param.h
index b898a8a297..82e234a42f 100644
--- a/libraries/AP_Common/AP_Param.h
+++ b/libraries/AP_Common/AP_Param.h
@@ -74,6 +74,12 @@ public:
         const struct GroupInfo *group_info;
     };
 
+    // a token used for first()/next() state
+    typedef struct {
+        uint8_t key;
+        uint8_t group_element;
+    } ParamToken;
+
     // called once at startup to setup the _var_info[] table. This
     // will also check the EEPROM header and re-initialise it if the
     // wrong version is found
@@ -138,15 +144,15 @@ public:
     /// @return             The first variable in _var_info, or NULL if
     ///                     there are none.
     ///
-    static AP_Param *first(uint16_t *token, enum ap_var_type *ptype);
+    static AP_Param *first(ParamToken *token, enum ap_var_type *ptype);
 
     /// Returns the next variable in _var_info, recursing into groups
     /// as needed
-    static AP_Param *next(uint16_t *token, enum ap_var_type *ptype);
+    static AP_Param *next(ParamToken *token, enum ap_var_type *ptype);
 
     /// Returns the next scalar variable in _var_info, recursing into groups
     /// as needed
-    static AP_Param *next_scalar(uint16_t *token, enum ap_var_type *ptype);
+    static AP_Param *next_scalar(ParamToken *token, enum ap_var_type *ptype);
 
     /// cast a variable to a float given its type
     float cast_to_float(enum ap_var_type type);
@@ -203,7 +209,7 @@ private:
                                 bool *found_current,
                                 uint8_t group_base,
                                 uint8_t group_shift,
-                                uint16_t *token,
+                                ParamToken *token,
                                 enum ap_var_type *ptype);
 
     static uint16_t _eeprom_size;