[BitBoard] Add fills and direction methods

BitBoard.cpp

@@ -31,3 +31,23 @@ BitBoard BitBoard::getRank(int r) {
 BitBoard BitBoard::genShift(BitBoard x, const int s) {
     return (s < 0) ? (x >> -s) : (s > 63) ? x : (x << s);
 }
+
+BitBoard BitBoard::northFill() const {
+    BitBoard result(mBoard);
+    result |= (result << 8);
+    result |= (result << 16);
+    result |= (result << 32);
+    return (result << 8);
+}
+
+BitBoard BitBoard::southFill() const {
+    BitBoard result(mBoard);
+    result |= (result >> 8);
+    result |= (result >> 16);
+    result |= (result >> 32);
+    return result;
+}
+
+BitBoard BitBoard::fileFill() const {
+    return northFill() | southFill();
+}