diff -r 434d6b8a406d -r ca9e48af31e6 MiniDisplay/FutabaVfd.cpp
--- a/MiniDisplay/FutabaVfd.cpp	Fri May 30 13:45:14 2014 +0200
+++ b/MiniDisplay/FutabaVfd.cpp	Fri May 30 15:02:15 2014 +0200
@@ -9,13 +9,8 @@
 #include <QTextStream>
 #endif
 
-//
-//
-//
 
-
-
-
+const int KNumberOfFrameBeforeDiffAlgo = 3;
 
 //
 //
@@ -79,6 +74,7 @@
 GP1212A01A::GP1212A01A():
 	iDisplayPositionX(0),iDisplayPositionY(0),
     iOffScreenMode(true),
+    iUseFrameDiffAlgo(true),
     iFrameNext(NULL),
     iFrameCurrent(NULL),
     iFramePrevious(NULL),
@@ -380,14 +376,15 @@
 	if (OffScreenMode())
 		{
 		//Send host back buffer to device back buffer
-        if (iNeedFullFrameUpdate<3)
+        if (!iUseFrameDiffAlgo || iNeedFullFrameUpdate<KNumberOfFrameBeforeDiffAlgo)
             {
-            //TODO: enable this once SendModifiedPixelBlocks works
             iNeedFullFrameUpdate++;
             SetPixelBlock(0,0,63,FrameBufferSizeInBytes(),iFrameNext->Ptr());
             }
         else
             {
+            //Frame diff algo is enabled
+            //We are going to send to our device only the differences between next frame and previous frame
             SendModifiedPixelBlocks();
             }
 		//Swap device front and back buffer
@@ -412,7 +409,6 @@
 /**
  * @brief GP1212A01A::SendModifiedPixelBlocks
  * Compare our back and front buffer and send to the device only the modified pixels.
- * TODO: Get this working at some point.
  */
 void GP1212A01A::SendModifiedPixelBlocks()
     {
@@ -420,13 +416,17 @@
     //const int KBlocksPerRow = WidthInPixels()/16; //16
     //const int KBlocksPerColumn = HeightInPixels()/16; //4
 
+    const int KPixelBlockEdge = 16;
+    const int KPixelBlockSizeInBits = KPixelBlockEdge*KPixelBlockEdge;
+    const int KPixelBlockSizeInBytes = KPixelBlockSizeInBits/8;
+
     int w=WidthInPixels();
     int h=HeightInPixels();
 
 
-
     //TODO: optimize with memcmp and 16 inc
     /*
+
     for (int i=0;i<w;i++)
         {
         for (int j=0;j<h;j++)
@@ -445,32 +445,34 @@
         }
     */
 
-    BitArray nextBlock(16*16);
-    BitArray previousBlock(16*16);
+    BitArray nextBlock(KPixelBlockSizeInBits);
+    BitArray previousBlock(KPixelBlockSizeInBits);
 
-    for (int i=0;i<w;i+=16)
+    for (int i=0;i<w;i+=KPixelBlockEdge)
         {
-        for (int j=0;j<h;j+=16)
+        for (int j=0;j<h;j+=KPixelBlockEdge)
             {
             //aX*HeightInPixels()+aY
             //int offset=(i*w/8)+(j/8);
 
 #ifdef DEBUG_FRAME_DIFF
-            QImage imagePrevious(16,16,QImage::Format_RGB32);
-            QImage imageNext(16,16,QImage::Format_RGB32);
+            QImage imagePrevious(KPixelBlockEdge,KPixelBlockEdge,QImage::Format_RGB32);
+            QImage imageNext(KPixelBlockEdge,KPixelBlockEdge,QImage::Format_RGB32);
 #endif
 
             //Get both our blocks from our buffers
-            for (int x=i;x<i+16;x++)
+            for (int x=i;x<i+KPixelBlockEdge;x++)
                 {
-                for (int y=j;y<j+16;y++)
+                for (int y=j;y<j+KPixelBlockEdge;y++)
                     {
-                    nextBlock.SetBitValue((x-i)*16+(y-j),(*iFrameNext)[x*h+y]);
-                    previousBlock.SetBitValue((x-i)*16+(y-j),(*iFramePrevious)[x*h+y]);
+                    int blockOffset=(x-i)*KPixelBlockEdge+(y-j);
+                    int frameOffset=x*h+y;
+                    nextBlock.SetBitValue(blockOffset,(*iFrameNext)[frameOffset]);
+                    previousBlock.SetBitValue(blockOffset,(*iFramePrevious)[frameOffset]);
 
 #ifdef DEBUG_FRAME_DIFF
-                    imageNext.setPixel(x-i,y-j,(nextBlock[(x-i)*16+(y-j)]?0xFFFFFFFF:0x00000000));
-                    imagePrevious.setPixel(x-i,y-j,(previousBlock[(x-i)*16+(y-j)]?0xFFFFFFFF:0x00000000));
+                    imageNext.setPixel(x-i,y-j,(nextBlock[blockOffset]?0xFFFFFFFF:0x00000000));
+                    imagePrevious.setPixel(x-i,y-j,(previousBlock[blockOffset]?0xFFFFFFFF:0x00000000));
 #endif
                     }
                 }
@@ -486,10 +488,10 @@
 
 
             //if (memcmp(iFrameNext->Ptr()+offset,iFramePrevious->Ptr()+offset,32 )) //32=(16*16/8)
-            if (memcmp(nextBlock.Ptr(),previousBlock.Ptr(),32 )!=0) //32=(16*16/8)
+            if (memcmp(nextBlock.Ptr(),previousBlock.Ptr(),KPixelBlockSizeInBytes)!=0)
                 {
                 //We need to update that block
-                SetPixelBlock(i,j,15,32,nextBlock.Ptr());
+                SetPixelBlock(i,j,KPixelBlockEdge-1,KPixelBlockSizeInBytes,nextBlock.Ptr());
                 //SetPixelBlock(i,j,15,32,0xFF/*nextBlock.Ptr()*/);
                 //SetDisplayPosition(iDisplayPositionX,OffScreenY());
                 //SetDisplayPosition(iDisplayPositionX,OffScreenY());