1 files changed, 5 insertions, 1 deletions
diff --git a/cell.h b/cell.h
index fc5f467..7041920 100644
--- a/cell.h
+++ b/cell.h
@@ -1,6 +1,10 @@
 #ifndef SUDOKU_CELL_H
 #define SUDOKU_CELL_H
 
+#define CELL_VALUE_MASK(x)          (1 << ((x)-1))
+#define CELL_SET_NOT(target, val)   ((target) |= CELL_VALUE_MASK(val))
+#define CELL_IS_NOT(cand, val)      ((cand & CELL_VALUE_MASK(val)))
+
 /* Description of a single cell on a sudoku board */
 struct cell
 {
@@ -10,7 +14,7 @@ struct cell
 	/* Array used to determine which values this cell can NOT be.
 	 * A non-zero value at index N indicates that this cell cannot have the
 	 * value N + 1 */
-	char not[9];
+	int not;
 };
 
 #endif /* SUDOKU_CELL_H */