+/// squares_aligned returns true if the squares s1, s2 and s3 are aligned
+/// either on a straight or on a diagonal line.
+
+inline bool squares_aligned(Square s1, Square s2, Square s3) {
+ return DirectionTable[s1][s2] != DELTA_NONE
+ && abs(DirectionTable[s1][s2]) == abs(DirectionTable[s2][s3]);
+}
+
+
+/// squares_straight_aligned returns true if the squares s1 and s2 are aligned
+/// on a straight line, either veritical or horizontal.
+
+inline bool squares_straight_aligned(Square s1, Square s2) {
+ return abs(DirectionTable[s1][s2]) == DELTA_N
+ || abs(DirectionTable[s1][s2]) == DELTA_E;
+}
+
+