+
+/// Extracting the signed lower and upper 16 bits is not so trivial because
+/// according to the standard a simple cast to short is implementation defined
+/// and so is a right shift of a signed integer.
+inline Value eg_value(Score s) {
+ union { uint16_t u; int16_t s; } eg = { uint16_t(unsigned(s + 0x8000) >> 16) };
+ return Value(eg.s);
+}
+
+inline Value mg_value(Score s) {
+ union { uint16_t u; int16_t s; } mg = { uint16_t(unsigned(s)) };
+ return Value(mg.s);
+}
+
+#define ENABLE_BASE_OPERATORS_ON(T) \
+constexpr T operator+(T d1, T d2) { return T(int(d1) + int(d2)); } \
+constexpr T operator-(T d1, T d2) { return T(int(d1) - int(d2)); } \
+constexpr T operator-(T d) { return T(-int(d)); } \
+inline T& operator+=(T& d1, T d2) { return d1 = d1 + d2; } \
+inline T& operator-=(T& d1, T d2) { return d1 = d1 - d2; }
+
+#define ENABLE_INCR_OPERATORS_ON(T) \
+inline T& operator++(T& d) { return d = T(int(d) + 1); } \
+inline T& operator--(T& d) { return d = T(int(d) - 1); }
+
+#define ENABLE_FULL_OPERATORS_ON(T) \
+ENABLE_BASE_OPERATORS_ON(T) \
+constexpr T operator*(int i, T d) { return T(i * int(d)); } \
+constexpr T operator*(T d, int i) { return T(int(d) * i); } \
+constexpr T operator/(T d, int i) { return T(int(d) / i); } \
+constexpr int operator/(T d1, T d2) { return int(d1) / int(d2); } \
+inline T& operator*=(T& d, int i) { return d = T(int(d) * i); } \
+inline T& operator/=(T& d, int i) { return d = T(int(d) / i); }
+
+ENABLE_FULL_OPERATORS_ON(Value)
+ENABLE_FULL_OPERATORS_ON(Direction)
+
+ENABLE_INCR_OPERATORS_ON(PieceType)
+ENABLE_INCR_OPERATORS_ON(Piece)
+ENABLE_INCR_OPERATORS_ON(Square)
+ENABLE_INCR_OPERATORS_ON(File)
+ENABLE_INCR_OPERATORS_ON(Rank)
+
+ENABLE_BASE_OPERATORS_ON(Score)
+
+#undef ENABLE_FULL_OPERATORS_ON
+#undef ENABLE_INCR_OPERATORS_ON
+#undef ENABLE_BASE_OPERATORS_ON
+
+/// Additional operators to add integers to a Value
+constexpr Value operator+(Value v, int i) { return Value(int(v) + i); }
+constexpr Value operator-(Value v, int i) { return Value(int(v) - i); }
+inline Value& operator+=(Value& v, int i) { return v = v + i; }
+inline Value& operator-=(Value& v, int i) { return v = v - i; }
+
+/// Additional operators to add a Direction to a Square
+constexpr Square operator+(Square s, Direction d) { return Square(int(s) + int(d)); }
+constexpr Square operator-(Square s, Direction d) { return Square(int(s) - int(d)); }
+inline Square& operator+=(Square& s, Direction d) { return s = s + d; }
+inline Square& operator-=(Square& s, Direction d) { return s = s - d; }
+
+/// Only declared but not defined. We don't want to multiply two scores due to
+/// a very high risk of overflow. So user should explicitly convert to integer.
+Score operator*(Score, Score) = delete;
+
+/// Division of a Score must be handled separately for each term
+inline Score operator/(Score s, int i) {
+ return make_score(mg_value(s) / i, eg_value(s) / i);
+}
+
+/// Multiplication of a Score by an integer. We check for overflow in debug mode.
+inline Score operator*(Score s, int i) {
+
+ Score result = Score(int(s) * i);
+
+ assert(eg_value(result) == (i * eg_value(s)));
+ assert(mg_value(result) == (i * mg_value(s)));
+ assert((i == 0) || (result / i) == s);
+
+ return result;
+}
+
+/// Multiplication of a Score by an boolean
+inline Score operator*(Score s, bool b) {
+ return Score(int(s) * int(b));
+}
+
+constexpr Color operator~(Color c) {
+ return Color(c ^ BLACK); // Toggle color
+}
+
+constexpr Square operator~(Square s) {
+ return Square(s ^ SQ_A8); // Vertical flip SQ_A1 -> SQ_A8
+}
+
+constexpr Piece operator~(Piece pc) {
+ return Piece(pc ^ 8); // Swap color of piece B_KNIGHT -> W_KNIGHT
+}
+
+inline File map_to_queenside(File f) {
+ return std::min(f, File(FILE_H - f)); // Map files ABCDEFGH to files ABCDDCBA
+}
+
+constexpr CastlingRights operator&(Color c, CastlingRights cr) {
+ return CastlingRights((c == WHITE ? WHITE_CASTLING : BLACK_CASTLING) & cr);
+}
+
+constexpr Value mate_in(int ply) {
+ return VALUE_MATE - ply;
+}
+
+constexpr Value mated_in(int ply) {
+ return -VALUE_MATE + ply;
+}
+
+constexpr Square make_square(File f, Rank r) {
+ return Square((r << 3) + f);
+}
+
+constexpr Piece make_piece(Color c, PieceType pt) {
+ return Piece((c << 3) + pt);
+}
+
+constexpr PieceType type_of(Piece pc) {
+ return PieceType(pc & 7);
+}
+
+inline Color color_of(Piece pc) {
+ assert(pc != NO_PIECE);
+ return Color(pc >> 3);
+}
+
+constexpr bool is_ok(Square s) {
+ return s >= SQ_A1 && s <= SQ_H8;
+}
+
+constexpr File file_of(Square s) {
+ return File(s & 7);
+}
+
+constexpr Rank rank_of(Square s) {
+ return Rank(s >> 3);
+}
+
+constexpr Square relative_square(Color c, Square s) {
+ return Square(s ^ (c * 56));
+}
+
+constexpr Rank relative_rank(Color c, Rank r) {
+ return Rank(r ^ (c * 7));
+}
+
+constexpr Rank relative_rank(Color c, Square s) {
+ return relative_rank(c, rank_of(s));
+}
+
+constexpr Direction pawn_push(Color c) {
+ return c == WHITE ? NORTH : SOUTH;
+}
+
+constexpr Square from_sq(Move m) {
+ return Square((m >> 6) & 0x3F);
+}
+
+constexpr Square to_sq(Move m) {
+ return Square(m & 0x3F);
+}
+
+constexpr int from_to(Move m) {
+ return m & 0xFFF;
+}
+
+constexpr MoveType type_of(Move m) {
+ return MoveType(m & (3 << 14));
+}
+
+constexpr PieceType promotion_type(Move m) {
+ return PieceType(((m >> 12) & 3) + KNIGHT);
+}
+
+constexpr Move make_move(Square from, Square to) {
+ return Move((from << 6) + to);
+}
+
+constexpr Move reverse_move(Move m) {
+ return make_move(to_sq(m), from_sq(m));
+}
+
+template<MoveType T>
+constexpr Move make(Square from, Square to, PieceType pt = KNIGHT) {
+ return Move(T + ((pt - KNIGHT) << 12) + (from << 6) + to);
+}
+
+constexpr bool is_ok(Move m) {
+ return from_sq(m) != to_sq(m); // Catch MOVE_NULL and MOVE_NONE