Factory Reset (#13)

Fixes https://github.com/awonak/alt-gravity/issues/1

Reviewed-on: https://git.pinkduck.xyz/awonak/libGravity/pulls/13

firmware/Gravity/save_state.cpp

@@ -26,7 +26,8 @@ bool StateManager::initialize(AppState& app) {
         return loadData(app, MAX_SAVE_SLOTS);
     } else {
         // EEPROM does not contain save data for this firmware & version.
-        // Initialize eeprom and save default patter to all save slots.
+        // Erase EEPROM and initialize state. Save default pattern to all save slots.
+        factoryReset();
         reset(app);
         _saveMetadata();
         // MAX_SAVE_SLOTS slot is reserved for transient state.
@@ -82,6 +83,15 @@ void StateManager::markDirty() {
     _lastChangeTime = millis();
 }
 
+// Erases all data in the EEPROM by writing 0 to every address.
+void StateManager::factoryReset() {
+    noInterrupts();
+    for (unsigned int i = 0 ; i < EEPROM.length() ; i++) {
+        EEPROM.write(i, 0);
+    }
+    interrupts();
+}
+
 bool StateManager::_isDataValid() {
     Metadata load_meta;
     EEPROM.get(0, load_meta);