2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
5 Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
7 Stockfish is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 Stockfish is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #ifndef BITBOARD_H_INCLUDED
22 #define BITBOARD_H_INCLUDED
31 bool probe(Square wksq, Square wpsq, Square bksq, Color us);
38 const std::string pretty(Bitboard b);
42 const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
44 const Bitboard FileABB = 0x0101010101010101ULL;
45 const Bitboard FileBBB = FileABB << 1;
46 const Bitboard FileCBB = FileABB << 2;
47 const Bitboard FileDBB = FileABB << 3;
48 const Bitboard FileEBB = FileABB << 4;
49 const Bitboard FileFBB = FileABB << 5;
50 const Bitboard FileGBB = FileABB << 6;
51 const Bitboard FileHBB = FileABB << 7;
53 const Bitboard Rank1BB = 0xFF;
54 const Bitboard Rank2BB = Rank1BB << (8 * 1);
55 const Bitboard Rank3BB = Rank1BB << (8 * 2);
56 const Bitboard Rank4BB = Rank1BB << (8 * 3);
57 const Bitboard Rank5BB = Rank1BB << (8 * 4);
58 const Bitboard Rank6BB = Rank1BB << (8 * 5);
59 const Bitboard Rank7BB = Rank1BB << (8 * 6);
60 const Bitboard Rank8BB = Rank1BB << (8 * 7);
62 extern int SquareDistance[SQUARE_NB][SQUARE_NB];
64 extern Bitboard SquareBB[SQUARE_NB];
65 extern Bitboard FileBB[FILE_NB];
66 extern Bitboard RankBB[RANK_NB];
67 extern Bitboard AdjacentFilesBB[FILE_NB];
68 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
69 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
70 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
71 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
72 extern Bitboard DistanceRingBB[SQUARE_NB][8];
73 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
74 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
75 extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
76 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
79 /// Overloads of bitwise operators between a Bitboard and a Square for testing
80 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
82 inline Bitboard operator&(Bitboard b, Square s) {
83 return b & SquareBB[s];
86 inline Bitboard operator|(Bitboard b, Square s) {
87 return b | SquareBB[s];
90 inline Bitboard operator^(Bitboard b, Square s) {
91 return b ^ SquareBB[s];
94 inline Bitboard& operator|=(Bitboard& b, Square s) {
95 return b |= SquareBB[s];
98 inline Bitboard& operator^=(Bitboard& b, Square s) {
99 return b ^= SquareBB[s];
102 inline bool more_than_one(Bitboard b) {
107 /// rank_bb() and file_bb() return a bitboard representing all the squares on
108 /// the given file or rank.
110 inline Bitboard rank_bb(Rank r) {
114 inline Bitboard rank_bb(Square s) {
115 return RankBB[rank_of(s)];
118 inline Bitboard file_bb(File f) {
122 inline Bitboard file_bb(Square s) {
123 return FileBB[file_of(s)];
127 /// shift() moves a bitboard one step along direction D. Mainly for pawns
130 inline Bitboard shift(Bitboard b) {
131 return D == NORTH ? b << 8 : D == SOUTH ? b >> 8
132 : D == NORTH_EAST ? (b & ~FileHBB) << 9 : D == SOUTH_EAST ? (b & ~FileHBB) >> 7
133 : D == NORTH_WEST ? (b & ~FileABB) << 7 : D == SOUTH_WEST ? (b & ~FileABB) >> 9
138 /// adjacent_files_bb() returns a bitboard representing all the squares on the
139 /// adjacent files of the given one.
141 inline Bitboard adjacent_files_bb(File f) {
142 return AdjacentFilesBB[f];
146 /// between_bb() returns a bitboard representing all the squares between the two
147 /// given ones. For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with
148 /// the bits for square d5 and e6 set. If s1 and s2 are not on the same rank, file
149 /// or diagonal, 0 is returned.
151 inline Bitboard between_bb(Square s1, Square s2) {
152 return BetweenBB[s1][s2];
156 /// in_front_bb() returns a bitboard representing all the squares on all the ranks
157 /// in front of the given one, from the point of view of the given color. For
158 /// instance, in_front_bb(BLACK, RANK_3) will return the squares on ranks 1 and 2.
160 inline Bitboard in_front_bb(Color c, Rank r) {
161 return InFrontBB[c][r];
165 /// forward_bb() returns a bitboard representing all the squares along the line
166 /// in front of the given one, from the point of view of the given color:
167 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
169 inline Bitboard forward_bb(Color c, Square s) {
170 return ForwardBB[c][s];
174 /// pawn_attack_span() returns a bitboard representing all the squares that can be
175 /// attacked by a pawn of the given color when it moves along its file, starting
176 /// from the given square:
177 /// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
179 inline Bitboard pawn_attack_span(Color c, Square s) {
180 return PawnAttackSpan[c][s];
184 /// passed_pawn_mask() returns a bitboard mask which can be used to test if a
185 /// pawn of the given color and on the given square is a passed pawn:
186 /// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_bb(c, s)
188 inline Bitboard passed_pawn_mask(Color c, Square s) {
189 return PassedPawnMask[c][s];
193 /// aligned() returns true if the squares s1, s2 and s3 are aligned either on a
194 /// straight or on a diagonal line.
196 inline bool aligned(Square s1, Square s2, Square s3) {
197 return LineBB[s1][s2] & s3;
201 /// distance() functions return the distance between x and y, defined as the
202 /// number of steps for a king in x to reach y. Works with squares, ranks, files.
204 template<typename T> inline int distance(T x, T y) { return x < y ? y - x : x - y; }
205 template<> inline int distance<Square>(Square x, Square y) { return SquareDistance[x][y]; }
207 template<typename T1, typename T2> inline int distance(T2 x, T2 y);
208 template<> inline int distance<File>(Square x, Square y) { return distance(file_of(x), file_of(y)); }
209 template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
212 /// attacks_bb() returns a bitboard representing all the squares attacked by a
213 /// piece of type Pt (bishop or rook) placed on 's'. The helper magic_index()
214 /// looks up the index using the 'magic bitboards' approach.
215 template<PieceType Pt>
216 inline unsigned magic_index(Square s, Bitboard occupied) {
218 extern Bitboard RookMasks[SQUARE_NB];
219 extern Bitboard RookMagics[SQUARE_NB];
220 extern unsigned RookShifts[SQUARE_NB];
221 extern Bitboard BishopMasks[SQUARE_NB];
222 extern Bitboard BishopMagics[SQUARE_NB];
223 extern unsigned BishopShifts[SQUARE_NB];
225 Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks;
226 Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics;
227 unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts;
230 return unsigned(pext(occupied, Masks[s]));
233 return unsigned(((occupied & Masks[s]) * Magics[s]) >> Shifts[s]);
235 unsigned lo = unsigned(occupied) & unsigned(Masks[s]);
236 unsigned hi = unsigned(occupied >> 32) & unsigned(Masks[s] >> 32);
237 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
240 template<PieceType Pt>
241 inline Bitboard attacks_bb(Square s, Bitboard occupied) {
243 extern Bitboard* RookAttacks[SQUARE_NB];
244 extern Bitboard* BishopAttacks[SQUARE_NB];
246 return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index<Pt>(s, occupied)];
249 inline Bitboard attacks_bb(Piece pc, Square s, Bitboard occupied) {
253 case BISHOP: return attacks_bb<BISHOP>(s, occupied);
254 case ROOK : return attacks_bb<ROOK>(s, occupied);
255 case QUEEN : return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
256 default : return StepAttacksBB[pc][s];
261 /// popcount() counts the number of non-zero bits in a bitboard
263 inline int popcount(Bitboard b) {
267 extern uint8_t PopCnt16[1 << 16];
268 union { Bitboard bb; uint16_t u[4]; } v = { b };
269 return PopCnt16[v.u[0]] + PopCnt16[v.u[1]] + PopCnt16[v.u[2]] + PopCnt16[v.u[3]];
271 #elif defined(_MSC_VER) || defined(__INTEL_COMPILER)
273 return (int)_mm_popcnt_u64(b);
275 #else // Assumed gcc or compatible compiler
277 return __builtin_popcountll(b);
283 /// lsb() and msb() return the least/most significant bit in a non-zero bitboard
285 #if defined(__GNUC__)
287 inline Square lsb(Bitboard b) {
289 return Square(__builtin_ctzll(b));
292 inline Square msb(Bitboard b) {
294 return Square(63 - __builtin_clzll(b));
297 #elif defined(_WIN64) && defined(_MSC_VER)
299 inline Square lsb(Bitboard b) {
302 _BitScanForward64(&idx, b);
306 inline Square msb(Bitboard b) {
309 _BitScanReverse64(&idx, b);
315 #define NO_BSF // Fallback on software implementation for other cases
317 Square lsb(Bitboard b);
318 Square msb(Bitboard b);
323 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard
325 inline Square pop_lsb(Bitboard* b) {
326 const Square s = lsb(*b);
332 /// frontmost_sq() and backmost_sq() return the square corresponding to the
333 /// most/least advanced bit relative to the given color.
335 inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); }
336 inline Square backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); }
338 #endif // #ifndef BITBOARD_H_INCLUDED