extern Bitboard QueenPseudoAttacks[64];
extern uint8_t BitCount8Bit[256];
+extern int8_t DirectionTable[64][64];
////
}
+/// 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;
+}
+
+
/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
/// pop_1st_bit() finds and clears the least significant nonzero bit in a
/// nonzero bitboard.