diff --git a/src/tiles.c b/src/tiles.c
new file mode 100644
index 00000000..32078abc
--- /dev/null
+++ b/src/tiles.c
@@ -0,0 +1,114 @@
+/* vim:expandtab:ts=2 sw=2:
+*/
+/*  Grafx2 - The Ultimate 256-color bitmap paint program
+
+    Copyright 2010 Adrien Destugues
+
+    Grafx2 is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License
+    as published by the Free Software Foundation; version 2
+    of the License.
+
+    Grafx2 is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Grafx2; if not, see <http://www.gnu.org/licenses/>
+*/
+
+/// \file Handle tiles.
+
+/// Build the tile-area from the current picture 
+void build_tile_area()
+{
+	word tileAreaWidth = Main_image_width / Snap_width + 1;
+	word tileAreaHeight = Main_image_height / Snap_height + 1;
+
+	int* tileArea = malloc(tileAreaWidth*tileAreaHeight*sizeof(int));
+
+	word tile_x, tile_y, pixel_x, pixel_y;
+
+	// For each tile, we have to crawl up to the top of the picture and
+	// find the first identical tile
+	for (tile_y = 0; tile_y < tileAreaWidth; tile_y++)
+		for(tile_x = 0; tile_x < tileAreaHeight; tile_x++)
+		{
+			// So, this is the "for each tile"
+			word ctx, cty;
+			// First we compare the tile with the others one in the same line at the left
+			for(ctx = tile_x - 1; ctx >= 0; ctx--)
+			if(compare_tiles(tile_x*Snap_width, tile_y*Snap_height, ctx*Snap_width, tile_y*Snap_height))
+			{
+				// We found a match !
+				tileArea[tile_y*tileAreaWidth+tile_x] = tile_y*tileAreaWidth+ctx;
+				goto found;
+			}
+
+			// Then we look at all the lines above
+			for(cty = tile_y - 1; cty >= 0; cty--)
+			for(ctx = tileAreaWidth - 1; ctx >= 0; ctx--)
+			if(compare_tiles(tile_x*Snap_width, tile_y*Snap_height, ctx*Snap_width, cty*Snap_height))
+			{
+				// We found a match !
+				tileArea[tile_y*tileAreaWidth+tile_x] = cty*tileAreaWidth+ctx;
+				goto found;
+			}
+
+			// Then we look at all the lines below
+			for(cty = tileAreaHeight - 1; cty >= tile_y; cty--)
+			for(ctx = tileAreaWidth - 1; ctx >= 0; ctx--)
+			if(compare_tiles(tile_x*Snap_width, tile_y*Snap_height, ctx*Snap_width, cty*Snap_height))
+			{
+				// We found a match !
+				tileArea[tile_y*tileAreaWidth+tile_x] = cty*tileAreaWidth+ctx;
+				goto found;
+			}
+			
+			// Then we look at the tiles at the right of this one
+			// (including the tile itself, so we are sure we match something this time)
+			for(ctx = tileAreaHeight; ctx >= tile_x; ctx--)
+			if(compare_tiles(tile_x*Snap_width, tile_y*Snap_height, ctx*Snap_width, tile_y*Snap_height))
+			{
+				// We found a match !
+				tileArea[tile_y*tileAreaWidth+tile_x] = tile_y*tileAreaWidth+ctx;
+			}
+			
+found:
+		}
+}
+
+
+// Compare tiles
+// The parameters are in pixel-space.
+void compare_tiles(word x1, word y1, word x2, word y2)
+{
+	word pixel_x, pixel_y;
+	byte c1, c2;
+
+	for (pixel_y = 0; pixel_y < Snap_width; pixel_y++)
+	for (pixel_x = 0; pixel_x < Snap_height; pixel_x++)
+	{
+		c1 = Main_screen + (y1+pixel_y) * Main_image_width + (x1+pixel_x);
+		c2 = Main_screen + (y2+pixel_y) * Main_image_width + (x2+pixel_x);
+		if (c1 != c2) return 0;
+	}
+
+	return 1;
+}
+
+/// Copy a tile pixeldata to all the identical ones
+// Call this after the end of an operation
+void update_tile(word pixel_x, word pixel_y)
+{
+	int tileOffset = (pixel_y/Snap_height)*tileAreaHeight + pixel_x/Snap_width;
+	int firstTileOffset = tileOffset + 1; // to make sure they are not equal
+
+	while(firstTileOffset != tileOffset)
+	{
+		tileOffset = tileArea[tileOffset];
+		
+		//do the copy of a block starting at (pixel_x, pixel_y)
+	}
+}