+typedef uint64_t Bitboard;
+
+const int MAX_MOVES = 192;
+const int MAX_PLY = 100;
+const int MAX_PLY_PLUS_2 = MAX_PLY + 2;
+
+const Bitboard FileABB = 0x0101010101010101ULL;
+const Bitboard FileBBB = FileABB << 1;
+const Bitboard FileCBB = FileABB << 2;
+const Bitboard FileDBB = FileABB << 3;
+const Bitboard FileEBB = FileABB << 4;
+const Bitboard FileFBB = FileABB << 5;
+const Bitboard FileGBB = FileABB << 6;
+const Bitboard FileHBB = FileABB << 7;
+
+const Bitboard Rank1BB = 0xFF;
+const Bitboard Rank2BB = Rank1BB << (8 * 1);
+const Bitboard Rank3BB = Rank1BB << (8 * 2);
+const Bitboard Rank4BB = Rank1BB << (8 * 3);
+const Bitboard Rank5BB = Rank1BB << (8 * 4);
+const Bitboard Rank6BB = Rank1BB << (8 * 5);
+const Bitboard Rank7BB = Rank1BB << (8 * 6);
+const Bitboard Rank8BB = Rank1BB << (8 * 7);
+
+
+/// A move needs 16 bits to be stored
+///
+/// bit 0- 5: destination square (from 0 to 63)
+/// bit 6-11: origin square (from 0 to 63)
+/// bit 12-13: promotion piece type - 2 (from KNIGHT-2 to QUEEN-2)
+/// bit 14-15: special move flag: promotion (1), en passant (2), castle (3)
+///
+/// Special cases are MOVE_NONE and MOVE_NULL. We can sneak these in because in
+/// any normal move destination square is always different from origin square
+/// while MOVE_NONE and MOVE_NULL have the same origin and destination square.
+
+enum Move {
+ MOVE_NONE = 0,
+ MOVE_NULL = 65
+};
+
+struct MoveStack {
+ Move move;
+ int score;
+};
+
+inline bool operator<(const MoveStack& f, const MoveStack& s) {
+ return f.score < s.score;
+}
+
+enum CastleRight {
+ CASTLES_NONE = 0,
+ WHITE_OO = 1,
+ BLACK_OO = 2,
+ WHITE_OOO = 4,
+ BLACK_OOO = 8,
+ ALL_CASTLES = 15
+};
+
+enum ScaleFactor {
+ SCALE_FACTOR_DRAW = 0,
+ SCALE_FACTOR_NORMAL = 64,
+ SCALE_FACTOR_MAX = 128,
+ SCALE_FACTOR_NONE = 255
+};
+
+enum Bound {
+ BOUND_NONE = 0,
+ BOUND_UPPER = 1,
+ BOUND_LOWER = 2,
+ BOUND_EXACT = BOUND_UPPER | BOUND_LOWER
+};
+
+enum Value {
+ VALUE_ZERO = 0,
+ VALUE_DRAW = 0,
+ VALUE_KNOWN_WIN = 15000,
+ VALUE_MATE = 30000,
+ VALUE_INFINITE = 30001,
+ VALUE_NONE = 30002,
+
+ VALUE_MATE_IN_MAX_PLY = VALUE_MATE - MAX_PLY,
+ VALUE_MATED_IN_MAX_PLY = -VALUE_MATE + MAX_PLY,
+
+ VALUE_ENSURE_INTEGER_SIZE_P = INT_MAX,
+ VALUE_ENSURE_INTEGER_SIZE_N = INT_MIN
+};
+
+enum PieceType {
+ NO_PIECE_TYPE = 0, ALL_PIECES = 0,
+ PAWN = 1, KNIGHT = 2, BISHOP = 3, ROOK = 4, QUEEN = 5, KING = 6
+};
+
+enum Piece {
+ NO_PIECE = 16, // color_of(NO_PIECE) == NO_COLOR
+ W_PAWN = 1, W_KNIGHT = 2, W_BISHOP = 3, W_ROOK = 4, W_QUEEN = 5, W_KING = 6,
+ B_PAWN = 9, B_KNIGHT = 10, B_BISHOP = 11, B_ROOK = 12, B_QUEEN = 13, B_KING = 14
+};
+
+enum Color {
+ WHITE, BLACK, NO_COLOR
+};
+
+enum Depth {
+
+ ONE_PLY = 2,
+
+ DEPTH_ZERO = 0 * ONE_PLY,
+ DEPTH_QS_CHECKS = -1 * ONE_PLY,
+ DEPTH_QS_NO_CHECKS = -2 * ONE_PLY,
+ DEPTH_QS_RECAPTURES = -5 * ONE_PLY,
+
+ DEPTH_NONE = -127 * ONE_PLY
+};
+
+enum Square {
+ SQ_A1, SQ_B1, SQ_C1, SQ_D1, SQ_E1, SQ_F1, SQ_G1, SQ_H1,
+ SQ_A2, SQ_B2, SQ_C2, SQ_D2, SQ_E2, SQ_F2, SQ_G2, SQ_H2,
+ SQ_A3, SQ_B3, SQ_C3, SQ_D3, SQ_E3, SQ_F3, SQ_G3, SQ_H3,
+ SQ_A4, SQ_B4, SQ_C4, SQ_D4, SQ_E4, SQ_F4, SQ_G4, SQ_H4,
+ SQ_A5, SQ_B5, SQ_C5, SQ_D5, SQ_E5, SQ_F5, SQ_G5, SQ_H5,
+ SQ_A6, SQ_B6, SQ_C6, SQ_D6, SQ_E6, SQ_F6, SQ_G6, SQ_H6,
+ SQ_A7, SQ_B7, SQ_C7, SQ_D7, SQ_E7, SQ_F7, SQ_G7, SQ_H7,
+ SQ_A8, SQ_B8, SQ_C8, SQ_D8, SQ_E8, SQ_F8, SQ_G8, SQ_H8,
+ SQ_NONE,
+
+ DELTA_N = 8,
+ DELTA_E = 1,
+ DELTA_S = -8,
+ DELTA_W = -1,
+
+ DELTA_NN = DELTA_N + DELTA_N,
+ DELTA_NE = DELTA_N + DELTA_E,
+ DELTA_SE = DELTA_S + DELTA_E,
+ DELTA_SS = DELTA_S + DELTA_S,
+ DELTA_SW = DELTA_S + DELTA_W,
+ DELTA_NW = DELTA_N + DELTA_W
+};
+
+enum File {
+ FILE_A, FILE_B, FILE_C, FILE_D, FILE_E, FILE_F, FILE_G, FILE_H
+};
+
+enum Rank {
+ RANK_1, RANK_2, RANK_3, RANK_4, RANK_5, RANK_6, RANK_7, RANK_8
+};
+
+
+/// Score enum keeps a midgame and an endgame value in a single integer (enum),
+/// first LSB 16 bits are used to store endgame value, while upper bits are used
+/// for midgame value. Compiler is free to choose the enum type as long as can
+/// keep its data, so ensure Score to be an integer type.
+enum Score {
+ SCORE_ZERO = 0,
+ SCORE_ENSURE_INTEGER_SIZE_P = INT_MAX,
+ SCORE_ENSURE_INTEGER_SIZE_N = INT_MIN
+};
+
+inline Score make_score(int mg, int eg) { return Score((mg << 16) + eg); }
+
+/// Extracting the signed lower and upper 16 bits it 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 mg_value(Score s) { return Value(((s + 32768) & ~0xffff) / 0x10000); }
+
+/// On Intel 64 bit we have a small speed regression with the standard conforming
+/// version, so use a faster code in this case that, although not 100% standard
+/// compliant it seems to work for Intel and MSVC.
+#if defined(IS_64BIT) && (!defined(__GNUC__) || defined(__INTEL_COMPILER))
+
+inline Value eg_value(Score s) { return Value(int16_t(s & 0xffff)); }
+
+#else
+
+inline Value eg_value(Score s) {
+ return Value((int)(unsigned(s) & 0x7fffu) - (int)(unsigned(s) & 0x8000u));
+}
+
+#endif
+
+#define ENABLE_SAFE_OPERATORS_ON(T) \
+inline T operator+(const T d1, const T d2) { return T(int(d1) + int(d2)); } \
+inline T operator-(const T d1, const T d2) { return T(int(d1) - int(d2)); } \
+inline T operator*(int i, const T d) { return T(i * int(d)); } \
+inline T operator*(const T d, int i) { return T(int(d) * i); } \
+inline T operator-(const T d) { return T(-int(d)); } \
+inline T& operator+=(T& d1, const T d2) { d1 = d1 + d2; return d1; } \
+inline T& operator-=(T& d1, const T d2) { d1 = d1 - d2; return d1; } \
+inline T& operator*=(T& d, int i) { d = T(int(d) * i); return d; }
+
+#define ENABLE_OPERATORS_ON(T) ENABLE_SAFE_OPERATORS_ON(T) \
+inline T operator++(T& d, int) { d = T(int(d) + 1); return d; } \
+inline T operator--(T& d, int) { d = T(int(d) - 1); return d; } \
+inline T operator/(const T d, int i) { return T(int(d) / i); } \
+inline T& operator/=(T& d, int i) { d = T(int(d) / i); return d; }
+
+ENABLE_OPERATORS_ON(Value)
+ENABLE_OPERATORS_ON(PieceType)
+ENABLE_OPERATORS_ON(Piece)
+ENABLE_OPERATORS_ON(Color)
+ENABLE_OPERATORS_ON(Depth)
+ENABLE_OPERATORS_ON(Square)
+ENABLE_OPERATORS_ON(File)
+ENABLE_OPERATORS_ON(Rank)
+
+/// Added operators for adding integers to a Value
+inline Value operator+(Value v, int i) { return Value(int(v) + i); }
+inline Value operator-(Value v, int i) { return Value(int(v) - i); }
+
+ENABLE_SAFE_OPERATORS_ON(Score)
+
+/// 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.
+inline Score operator*(Score s1, Score s2);
+
+/// 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);
+}
+
+/// Weight score v by score w trying to prevent overflow
+inline Score apply_weight(Score v, Score w) {
+ return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
+ (int(eg_value(v)) * eg_value(w)) / 0x100);
+}
+
+#undef ENABLE_OPERATORS_ON
+#undef ENABLE_SAFE_OPERATORS_ON
+
+const Value PawnValueMidgame = Value(0x0C6);
+const Value PawnValueEndgame = Value(0x102);
+const Value KnightValueMidgame = Value(0x331);
+const Value KnightValueEndgame = Value(0x34E);
+const Value BishopValueMidgame = Value(0x344);
+const Value BishopValueEndgame = Value(0x359);
+const Value RookValueMidgame = Value(0x4F6);
+const Value RookValueEndgame = Value(0x4FE);
+const Value QueenValueMidgame = Value(0x9D9);
+const Value QueenValueEndgame = Value(0x9FE);
+
+extern const Value PieceValueMidgame[17]; // Indexed by Piece or PieceType
+extern const Value PieceValueEndgame[17];
+extern int SquareDistance[64][64];
+extern uint8_t BitCount8Bit[256];
+
+inline Color operator~(Color c) {
+ return Color(c ^ 1);
+}
+
+inline Square operator~(Square s) {
+ return Square(s ^ 56); // Vertical flip SQ_A1 -> SQ_A8
+}
+
+inline Value mate_in(int ply) {
+ return VALUE_MATE - ply;
+}
+
+inline Value mated_in(int ply) {
+ return -VALUE_MATE + ply;
+}
+
+inline Piece make_piece(Color c, PieceType pt) {
+ return Piece((c << 3) | pt);
+}
+
+inline PieceType type_of(Piece p) {
+ return PieceType(p & 7);
+}
+
+inline Color color_of(Piece p) {
+ return Color(p >> 3);
+}
+
+inline Square make_square(File f, Rank r) {
+ return Square((r << 3) | f);
+}
+
+inline bool is_ok(Square s) {
+ return s >= SQ_A1 && s <= SQ_H8;
+}
+
+inline File file_of(Square s) {
+ return File(s & 7);
+}
+
+inline Rank rank_of(Square s) {
+ return Rank(s >> 3);
+}
+
+inline Square mirror(Square s) {
+ return Square(s ^ 7); // Horizontal flip SQ_A1 -> SQ_H1
+}
+
+inline Square relative_square(Color c, Square s) {
+ return Square(s ^ (c * 56));
+}
+
+inline Rank relative_rank(Color c, Rank r) {
+ return Rank(r ^ (c * 7));
+}
+
+inline Rank relative_rank(Color c, Square s) {
+ return relative_rank(c, rank_of(s));
+}
+
+inline bool opposite_colors(Square s1, Square s2) {
+ int s = s1 ^ s2;
+ return ((s >> 3) ^ s) & 1;
+}
+
+inline int file_distance(Square s1, Square s2) {
+ return abs(file_of(s1) - file_of(s2));
+}
+
+inline int rank_distance(Square s1, Square s2) {
+ return abs(rank_of(s1) - rank_of(s2));
+}
+
+inline int square_distance(Square s1, Square s2) {
+ return SquareDistance[s1][s2];
+}
+
+inline char piece_type_to_char(PieceType pt) {
+ return " PNBRQK"[pt];
+}
+
+inline char file_to_char(File f) {
+ return char(f - FILE_A + int('a'));
+}
+
+inline char rank_to_char(Rank r) {
+ return char(r - RANK_1 + int('1'));
+}
+
+inline Square pawn_push(Color c) {
+ return c == WHITE ? DELTA_N : DELTA_S;
+}
+
+inline Square from_sq(Move m) {
+ return Square((m >> 6) & 0x3F);
+}
+
+inline Square to_sq(Move m) {
+ return Square(m & 0x3F);
+}
+
+inline bool is_special(Move m) {
+ return m & (3 << 14);
+}
+
+inline bool is_promotion(Move m) {
+ return (m & (3 << 14)) == (1 << 14);
+}
+
+inline int is_enpassant(Move m) {
+ return (m & (3 << 14)) == (2 << 14);
+}
+
+inline int is_castle(Move m) {
+ return (m & (3 << 14)) == (3 << 14);
+}
+
+inline PieceType promotion_type(Move m) {
+ return PieceType(((m >> 12) & 3) + 2);
+}
+
+inline Move make_move(Square from, Square to) {
+ return Move(to | (from << 6));
+}
+
+inline Move make_promotion(Square from, Square to, PieceType pt) {
+ return Move(to | (from << 6) | (1 << 14) | ((pt - 2) << 12)) ;
+}
+
+inline Move make_enpassant(Square from, Square to) {
+ return Move(to | (from << 6) | (2 << 14));
+}
+
+inline Move make_castle(Square from, Square to) {
+ return Move(to | (from << 6) | (3 << 14));
+}
+
+inline bool is_ok(Move m) {
+ return from_sq(m) != to_sq(m); // Catches also MOVE_NULL and MOVE_NONE
+}
+
+#include <string>
+
+inline const std::string square_to_string(Square s) {
+ char ch[] = { file_to_char(file_of(s)), rank_to_char(rank_of(s)), 0 };
+ return ch;
+}
+
+/// Our insertion sort implementation, works with pointers and iterators and is
+/// guaranteed to be stable, as is needed.
+template<typename T, typename K>
+void sort(K first, K last)
+{
+ T tmp;
+ K p, q;
+
+ for (p = first + 1; p < last; p++)
+ {
+ tmp = *p;
+ for (q = p; q != first && *(q-1) < tmp; --q)
+ *q = *(q-1);
+ *q = tmp;
+ }
+}