AP_Param: add support for converting between old and new parameters

this allows for a conversion table between old parameters and new
parameters, making firmware upgrades with moved parameters much easier
for users

libraries/AP_Param/AP_Param.cpp

@@ -608,6 +608,17 @@ AP_Param::find(const char *name, enum ap_var_type *ptype)
     return NULL;
 }
 
+// Find a variable by name.
+//
+AP_Param *
+AP_Param::find_P(const prog_char_t *name, enum ap_var_type *ptype)
+{
+    char param_name[AP_MAX_NAME_SIZE+1];
+    strncpy_P(param_name, name, AP_MAX_NAME_SIZE);
+    param_name[AP_MAX_NAME_SIZE] = 0;
+    return find(param_name, ptype);
+}
+
 // Find a variable by index. Note that this is quite slow.
 //
 AP_Param *
@@ -705,6 +716,7 @@ bool AP_Param::save(void)
 
     if (ofs+type_size((enum ap_var_type)phdr.type)+2*sizeof(phdr) >= _eeprom_size) {
         // we are out of room for saving variables
+        hal.console->println_P(PSTR("EEPROM full"));
         return false;
     }
 
@@ -770,20 +782,20 @@ bool AP_Param::load(void)
 }
 
 // set a AP_Param variable to a specified value
-void AP_Param::set_value(enum ap_var_type type, void *ptr, float def_value)
+void AP_Param::set_value(enum ap_var_type type, void *ptr, float value)
 {
     switch (type) {
     case AP_PARAM_INT8:
-        ((AP_Int8 *)ptr)->set(def_value);
+        ((AP_Int8 *)ptr)->set(value);
         break;
     case AP_PARAM_INT16:
-        ((AP_Int16 *)ptr)->set(def_value);
+        ((AP_Int16 *)ptr)->set(value);
         break;
     case AP_PARAM_INT32:
-        ((AP_Int32 *)ptr)->set(def_value);
+        ((AP_Int32 *)ptr)->set(value);
         break;
     case AP_PARAM_FLOAT:
-        ((AP_Float *)ptr)->set(def_value);
+        ((AP_Float *)ptr)->set(value);
         break;
     default:
         break;
@@ -1054,3 +1066,72 @@ void AP_Param::show_all(AP_HAL::BetterStream *port)
     }
 }
 
+// convert one old vehicle parameter to new object parameter
+void AP_Param::convert_old_parameter(const struct ConversionInfo *info)
+{
+
+    // find the old value in EEPROM.
+    uint16_t pofs;
+    AP_Param::Param_header header;
+    header.type = PGM_UINT8(&info->type);
+    header.key = PGM_UINT8(&info->old_key);
+    header.group_element = PGM_UINT8(&info->old_group_element);
+    if (!scan(&header, &pofs)) {
+        // the old parameter isn't saved in the EEPROM. It was
+        // probably still set to the default value, which isn't stored
+        // no need to convert
+        return;
+    }
+
+    // load the old value from EEPROM
+    uint8_t old_value[type_size((enum ap_var_type)header.type)];
+    hal.storage->read_block(old_value, pofs+sizeof(header), sizeof(old_value));
+    const AP_Param *ap = (const AP_Param *)&old_value[0];
+
+    // find the new variable in the variable structures
+    enum ap_var_type ptype;
+    AP_Param *ap2;
+    ap2 = find_P((const prog_char_t *)&info->new_name[0], &ptype);
+    if (ap2 == NULL) {
+        hal.console->printf_P(PSTR("Unknown conversion '%S'\n"), info->new_name);
+        return;
+    }
+
+    // see if we can load it from EEPROM
+    if (ap2->load()) {
+        // the new parameter already has a value set by the user, or
+        // has already been converted
+        return;
+    }
+
+    // see if they are the same type
+    if (ptype == header.type) {
+        // copy the value over only if the new parameter does not already
+        // have the old value (via a default).
+        if (memcmp(ap2, ap, sizeof(old_value)) != 0) {
+            memcpy(ap2, ap, sizeof(old_value));
+            // and save
+            ap2->save();
+        }
+    } else if (ptype <= AP_PARAM_FLOAT && header.type <= AP_PARAM_FLOAT) {
+        // perform scalar->scalar conversion
+        float v = ap->cast_to_float((enum ap_var_type)header.type);
+        if (v != ap2->cast_to_float(ptype)) {
+            // the value needs to change
+            set_value(ptype, ap2, v);
+            ap2->save();
+        }
+    } else {
+        // can't do vector<->scalar conversion, or different vector types
+        hal.console->printf_P(PSTR("Bad conversion type '%S'\n"), info->new_name);
+    }
+}
+
+
+// convert old vehicle parameters to new object parametersv
+void AP_Param::convert_old_parameters(const struct ConversionInfo *conversion_table, uint8_t table_size)
+{
+    for (uint8_t i=0; i<table_size; i++) {
+        convert_old_parameter(&conversion_table[i]);
+    }
+}

libraries/AP_Param/AP_Param.h

@@ -83,6 +83,12 @@ public:
             const float def_value;
         };
     };
+    struct ConversionInfo {
+        uint8_t old_key; // k_param_*
+        uint8_t old_group_element; // index in old object
+        enum ap_var_type type; // AP_PARAM_*
+        const char new_name[AP_MAX_NAME_SIZE+1];        
+    };
 
     // called once at startup to setup the _var_info[] table. This
     // will also check the EEPROM header and re-initialise it if the
@@ -137,6 +143,7 @@ public:
     ///                         it does not exist.
     ///
     static AP_Param * find(const char *name, enum ap_var_type *ptype);
+    static AP_Param * find_P(const prog_char_t *name, enum ap_var_type *ptype);
 
     /// Find a variable by index.
     ///
@@ -187,6 +194,9 @@ public:
     // does not recurse into the sub-objects    
     static void         setup_sketch_defaults(void);
 
+    // convert old vehicle parameters to new object parameters
+    static void         convert_old_parameters(const struct ConversionInfo *conversion_table, uint8_t table_size);
+
     /// Erase all variables in EEPROM.
     ///
     static void         erase_all(void);
@@ -300,7 +310,7 @@ private:
                                     const struct GroupInfo *group_info,
                                     enum ap_var_type *ptype);
     static void                 write_sentinal(uint16_t ofs);
-    bool                        scan(
+    static bool                 scan(
                                     const struct Param_header *phdr,
                                     uint16_t *pofs);
     static uint8_t				type_size(enum ap_var_type type);
@@ -325,6 +335,9 @@ private:
     static const uint8_t        k_EEPROM_magic0      = 0x50;
     static const uint8_t        k_EEPROM_magic1      = 0x41; ///< "AP"
     static const uint8_t        k_EEPROM_revision    = 6; ///< current format revision
+
+    // convert old vehicle parameters to new object parameters
+    static void         convert_old_parameter(const struct ConversionInfo *info);
 };
 
 /// Template class for scalar variables.