+ /* We try to spot a "complete" subtexture "above" ROW, COL;
+ * this texture is given by appropriate rounding of WIDTH x ROW.
+ * Then we just add the amount left (usually on the left).
+ *
+ * Example for X*Y microtiles (Z bytes each)
+ * offset = Z * (((width + X - 1) / X) * (row / Y) + col / X);
+ */
+