From b3a503a9ef11df415faf5dcfb454f7dd9d3f074e Mon Sep 17 00:00:00 2001
From: timw1971 <tim@accuix.com>
Date: Fri, 15 Jan 2016 15:15:22 +0000
Subject: [PATCH] Optimised _dirty flag.

_dirty set only if the value being written is different from the existing value in the cache.
---
 libraries/EEPROM/EEPROM.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/libraries/EEPROM/EEPROM.cpp b/libraries/EEPROM/EEPROM.cpp
index 41c484306..29e9579ac 100644
--- a/libraries/EEPROM/EEPROM.cpp
+++ b/libraries/EEPROM/EEPROM.cpp
@@ -86,8 +86,13 @@ void EEPROMClass::write(int address, uint8_t value) {
   if(!_data)
     return;
 
-  _data[address] = value;
-  _dirty = true;
+  // Optimise _dirty. Only flagged if data written is different.
+  uint8_t* pData = &_data[address];
+  if (*pData != value)
+  {
+    *pData = value;
+    _dirty = true;
+  }
 }
 
 bool EEPROMClass::commit() {