2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (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 const std::string pretty(Bitboard b);
38 bool probe_kpk(Square wksq, Square wpsq, Square bksq, Color us);
42 const Bitboard FileABB = 0x0101010101010101ULL;
43 const Bitboard FileBBB = FileABB << 1;
44 const Bitboard FileCBB = FileABB << 2;
45 const Bitboard FileDBB = FileABB << 3;
46 const Bitboard FileEBB = FileABB << 4;
47 const Bitboard FileFBB = FileABB << 5;
48 const Bitboard FileGBB = FileABB << 6;
49 const Bitboard FileHBB = FileABB << 7;
51 const Bitboard Rank1BB = 0xFF;
52 const Bitboard Rank2BB = Rank1BB << (8 * 1);
53 const Bitboard Rank3BB = Rank1BB << (8 * 2);
54 const Bitboard Rank4BB = Rank1BB << (8 * 3);
55 const Bitboard Rank5BB = Rank1BB << (8 * 4);
56 const Bitboard Rank6BB = Rank1BB << (8 * 5);
57 const Bitboard Rank7BB = Rank1BB << (8 * 6);
58 const Bitboard Rank8BB = Rank1BB << (8 * 7);
60 extern Bitboard RMasks[SQUARE_NB];
61 extern Bitboard RMagics[SQUARE_NB];
62 extern Bitboard* RAttacks[SQUARE_NB];
63 extern unsigned RShifts[SQUARE_NB];
65 extern Bitboard BMasks[SQUARE_NB];
66 extern Bitboard BMagics[SQUARE_NB];
67 extern Bitboard* BAttacks[SQUARE_NB];
68 extern unsigned BShifts[SQUARE_NB];
70 extern Bitboard SquareBB[SQUARE_NB];
71 extern Bitboard FileBB[FILE_NB];
72 extern Bitboard RankBB[RANK_NB];
73 extern Bitboard AdjacentFilesBB[FILE_NB];
74 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
75 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
76 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
77 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
78 extern Bitboard DistanceRingsBB[SQUARE_NB][8];
79 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
80 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
81 extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
82 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
84 extern int SquareDistance[SQUARE_NB][SQUARE_NB];
86 const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
88 /// Overloads of bitwise operators between a Bitboard and a Square for testing
89 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
91 inline Bitboard operator&(Bitboard b, Square s) {
92 return b & SquareBB[s];
95 inline Bitboard& operator|=(Bitboard& b, Square s) {
96 return b |= SquareBB[s];
99 inline Bitboard& operator^=(Bitboard& b, Square s) {
100 return b ^= SquareBB[s];
103 inline Bitboard operator|(Bitboard b, Square s) {
104 return b | SquareBB[s];
107 inline Bitboard operator^(Bitboard b, Square s) {
108 return b ^ SquareBB[s];
111 inline bool more_than_one(Bitboard b) {
115 template<typename T> inline int distance(T x, T y) { return x < y ? y - x : x - y; }
116 template<> inline int distance<Square>(Square x, Square y) { return SquareDistance[x][y]; }
118 template<typename T1, typename T2> inline int distance(T2 x, T2 y);
119 template<> inline int distance<File>(Square x, Square y) { return distance(file_of(x), file_of(y)); }
120 template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
123 /// shift_bb() moves bitboard one step along direction Delta. Mainly for pawns.
125 template<Square Delta>
126 inline Bitboard shift_bb(Bitboard b) {
128 return Delta == DELTA_N ? b << 8 : Delta == DELTA_S ? b >> 8
129 : Delta == DELTA_NE ? (b & ~FileHBB) << 9 : Delta == DELTA_SE ? (b & ~FileHBB) >> 7
130 : Delta == DELTA_NW ? (b & ~FileABB) << 7 : Delta == DELTA_SW ? (b & ~FileABB) >> 9
135 /// rank_bb() and file_bb() take a file or a square as input and return
136 /// a bitboard representing all squares on the given file or rank.
138 inline Bitboard rank_bb(Rank r) {
142 inline Bitboard rank_bb(Square s) {
143 return RankBB[rank_of(s)];
146 inline Bitboard file_bb(File f) {
150 inline Bitboard file_bb(Square s) {
151 return FileBB[file_of(s)];
155 /// adjacent_files_bb() takes a file as input and returns a bitboard representing
156 /// all squares on the adjacent files.
158 inline Bitboard adjacent_files_bb(File f) {
159 return AdjacentFilesBB[f];
163 /// in_front_bb() takes a color and a rank as input, and returns a bitboard
164 /// representing all the squares on all ranks in front of the rank, from the
165 /// given color's point of view. For instance, in_front_bb(BLACK, RANK_3) will
166 /// give all squares on ranks 1 and 2.
168 inline Bitboard in_front_bb(Color c, Rank r) {
169 return InFrontBB[c][r];
173 /// between_bb() returns a bitboard representing all squares between two squares.
174 /// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
175 /// square d5 and e6 set. If s1 and s2 are not on the same rank, file or diagonal,
178 inline Bitboard between_bb(Square s1, Square s2) {
179 return BetweenBB[s1][s2];
183 /// forward_bb() takes a color and a square as input, and returns a bitboard
184 /// representing all squares along the line in front of the square, from the
185 /// point of view of the given color. Definition of the table is:
186 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
188 inline Bitboard forward_bb(Color c, Square s) {
189 return ForwardBB[c][s];
193 /// pawn_attack_span() takes a color and a square as input, and returns a bitboard
194 /// representing all squares that can be attacked by a pawn of the given color
195 /// when it moves along its file starting from the given square. Definition is:
196 /// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
198 inline Bitboard pawn_attack_span(Color c, Square s) {
199 return PawnAttackSpan[c][s];
203 /// passed_pawn_mask() takes a color and a square as input, and returns a
204 /// bitboard mask which can be used to test if a pawn of the given color on
205 /// the given square is a passed pawn. Definition of the table is:
206 /// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_bb(c, s)
208 inline Bitboard passed_pawn_mask(Color c, Square s) {
209 return PassedPawnMask[c][s];
213 /// squares_of_color() returns a bitboard representing all squares with the same
214 /// color of the given square.
216 inline Bitboard squares_of_color(Square s) {
217 return DarkSquares & s ? DarkSquares : ~DarkSquares;
221 /// aligned() returns true if the squares s1, s2 and s3 are aligned
222 /// either on a straight or on a diagonal line.
224 inline bool aligned(Square s1, Square s2, Square s3) {
225 return LineBB[s1][s2] & s3;
229 /// Functions for computing sliding attack bitboards. Function attacks_bb() takes
230 /// a square and a bitboard of occupied squares as input, and returns a bitboard
231 /// representing all squares attacked by Pt (bishop or rook) on the given square.
232 template<PieceType Pt>
233 FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
235 Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
236 Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
237 unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
240 return unsigned(_pext_u64(occ, Masks[s]));
243 return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
245 unsigned lo = unsigned(occ) & unsigned(Masks[s]);
246 unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
247 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
250 template<PieceType Pt>
251 inline Bitboard attacks_bb(Square s, Bitboard occ) {
252 return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
255 inline Bitboard attacks_bb(Piece pc, Square s, Bitboard occ) {
259 case BISHOP: return attacks_bb<BISHOP>(s, occ);
260 case ROOK : return attacks_bb<ROOK>(s, occ);
261 case QUEEN : return attacks_bb<BISHOP>(s, occ) | attacks_bb<ROOK>(s, occ);
262 default : return StepAttacksBB[pc][s];
266 /// lsb()/msb() finds the least/most significant bit in a non-zero bitboard.
267 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard.
271 # if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
273 FORCE_INLINE Square lsb(Bitboard b) {
275 _BitScanForward64(&idx, b);
279 FORCE_INLINE Square msb(Bitboard b) {
281 _BitScanReverse64(&idx, b);
285 # elif defined(__arm__)
287 FORCE_INLINE int lsb32(uint32_t v) {
288 __asm__("rbit %0, %1" : "=r"(v) : "r"(v));
289 return __builtin_clz(v);
292 FORCE_INLINE Square msb(Bitboard b) {
293 return (Square) (63 - __builtin_clzll(b));
296 FORCE_INLINE Square lsb(Bitboard b) {
297 return (Square) (uint32_t(b) ? lsb32(uint32_t(b)) : 32 + lsb32(uint32_t(b >> 32)));
302 FORCE_INLINE Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen
304 __asm__("bsfq %1, %0": "=r"(idx): "rm"(b) );
308 FORCE_INLINE Square msb(Bitboard b) {
310 __asm__("bsrq %1, %0": "=r"(idx): "rm"(b) );
316 FORCE_INLINE Square pop_lsb(Bitboard* b) {
317 const Square s = lsb(*b);
322 #else // if defined(USE_BSFQ)
324 extern Square msb(Bitboard b);
325 extern Square lsb(Bitboard b);
326 extern Square pop_lsb(Bitboard* b);
330 /// frontmost_sq() and backmost_sq() find the square corresponding to the
331 /// most/least advanced bit relative to the given color.
333 inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); }
334 inline Square backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); }
336 #endif // #ifndef BITBOARD_H_INCLUDED