2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2013 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 #if !defined(BITBOARD_H_INCLUDED)
22 #define BITBOARD_H_INCLUDED
29 void print(Bitboard b);
36 bool probe_kpk(Square wksq, Square wpsq, Square bksq, Color us);
42 extern Bitboard RMasks[SQUARE_NB];
43 extern Bitboard RMagics[SQUARE_NB];
44 extern Bitboard* RAttacks[SQUARE_NB];
45 extern unsigned RShifts[SQUARE_NB];
47 extern Bitboard BMasks[SQUARE_NB];
48 extern Bitboard BMagics[SQUARE_NB];
49 extern Bitboard* BAttacks[SQUARE_NB];
50 extern unsigned BShifts[SQUARE_NB];
52 extern Bitboard SquareBB[SQUARE_NB];
53 extern Bitboard FileBB[FILE_NB];
54 extern Bitboard RankBB[RANK_NB];
55 extern Bitboard AdjacentFilesBB[FILE_NB];
56 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
57 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
58 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
59 extern Bitboard DistanceRingsBB[SQUARE_NB][8];
60 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
61 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
62 extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
63 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
65 const Bitboard BlackSquares = 0xAA55AA55AA55AA55ULL;
67 /// Overloads of bitwise operators between a Bitboard and a Square for testing
68 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
70 inline Bitboard operator&(Bitboard b, Square s) {
71 return b & SquareBB[s];
74 inline Bitboard& operator|=(Bitboard& b, Square s) {
75 return b |= SquareBB[s];
78 inline Bitboard& operator^=(Bitboard& b, Square s) {
79 return b ^= SquareBB[s];
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];
91 /// more_than_one() returns true if in 'b' there is more than one bit set
93 inline bool more_than_one(Bitboard b) {
98 /// shift_bb() moves bitboard one step along direction Delta. Mainly for pawns.
100 template<Square Delta>
101 inline Bitboard shift_bb(Bitboard b) {
103 return Delta == DELTA_N ? b << 8 : Delta == DELTA_S ? b >> 8
104 : Delta == DELTA_NE ? (b & ~FileHBB) << 9 : Delta == DELTA_SE ? (b & ~FileHBB) >> 7
105 : Delta == DELTA_NW ? (b & ~FileABB) << 7 : Delta == DELTA_SW ? (b & ~FileABB) >> 9
110 /// rank_bb() and file_bb() take a file or a square as input and return
111 /// a bitboard representing all squares on the given file or rank.
113 inline Bitboard rank_bb(Rank r) {
117 inline Bitboard rank_bb(Square s) {
118 return RankBB[rank_of(s)];
121 inline Bitboard file_bb(File f) {
125 inline Bitboard file_bb(Square s) {
126 return FileBB[file_of(s)];
130 /// adjacent_files_bb takes a file as input and returns a bitboard representing
131 /// all squares on the adjacent files.
133 inline Bitboard adjacent_files_bb(File f) {
134 return AdjacentFilesBB[f];
138 /// in_front_bb() takes a color and a rank or square as input, and returns a
139 /// bitboard representing all the squares on all ranks in front of the rank
140 /// (or square), from the given color's point of view. For instance,
141 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
142 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
144 inline Bitboard in_front_bb(Color c, Rank r) {
145 return InFrontBB[c][r];
148 inline Bitboard in_front_bb(Color c, Square s) {
149 return InFrontBB[c][rank_of(s)];
153 /// between_bb returns a bitboard representing all squares between two squares.
154 /// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
155 /// square d5 and e6 set. If s1 and s2 are not on the same line, file or diagonal,
158 inline Bitboard between_bb(Square s1, Square s2) {
159 return BetweenBB[s1][s2];
163 /// forward_bb takes a color and a square as input, and returns a bitboard
164 /// representing all squares along the line in front of the square, from the
165 /// point of view of the given color. Definition of the table is:
166 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
168 inline Bitboard forward_bb(Color c, Square s) {
169 return ForwardBB[c][s];
173 /// passed_pawn_mask takes a color and a square as input, and returns a
174 /// bitboard mask which can be used to test if a pawn of the given color on
175 /// the given square is a passed pawn. Definition of the table is:
176 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(s)
178 inline Bitboard passed_pawn_mask(Color c, Square s) {
179 return PassedPawnMask[c][s];
183 /// attack_span_mask takes a color and a square as input, and returns a bitboard
184 /// representing all squares that can be attacked by a pawn of the given color
185 /// when it moves along its file starting from the given square. Definition is:
186 /// AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
188 inline Bitboard pawn_attack_span(Color c, Square s) {
189 return PawnAttackSpan[c][s];
193 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
194 /// either on a straight or on a diagonal line.
196 inline bool squares_aligned(Square s1, Square s2, Square s3) {
197 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
198 & ( SquareBB[s1] | SquareBB[s2] | SquareBB[s3]);
202 /// same_color_squares() returns a bitboard representing all squares with
203 /// the same color of the given square.
205 inline Bitboard same_color_squares(Square s) {
206 return BlackSquares & s ? BlackSquares : ~BlackSquares;
210 /// Functions for computing sliding attack bitboards. Function attacks_bb() takes
211 /// a square and a bitboard of occupied squares as input, and returns a bitboard
212 /// representing all squares attacked by Pt (bishop or rook) on the given square.
213 template<PieceType Pt>
214 FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
216 Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
217 Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
218 unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
221 return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
223 unsigned lo = unsigned(occ) & unsigned(Masks[s]);
224 unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
225 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
228 template<PieceType Pt>
229 inline Bitboard attacks_bb(Square s, Bitboard occ) {
230 return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
234 /// lsb()/msb() finds the least/most significant bit in a nonzero bitboard.
235 /// pop_lsb() finds and clears the least significant bit in a nonzero bitboard.
237 #if defined(USE_BSFQ)
239 # if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
241 FORCE_INLINE Square lsb(Bitboard b) {
243 _BitScanForward64(&index, b);
244 return (Square) index;
247 FORCE_INLINE Square msb(Bitboard b) {
249 _BitScanReverse64(&index, b);
250 return (Square) index;
253 # elif defined(__arm__)
255 FORCE_INLINE int lsb32(uint32_t v) {
256 __asm__("rbit %0, %1" : "=r"(v) : "r"(v));
257 return __builtin_clz(v);
260 FORCE_INLINE Square msb(Bitboard b) {
261 return (Square) (63 - __builtin_clzll(b));
264 FORCE_INLINE Square lsb(Bitboard b) {
265 return (Square) (uint32_t(b) ? lsb32(uint32_t(b)) : 32 + lsb32(uint32_t(b >> 32)));
270 FORCE_INLINE Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen
272 __asm__("bsfq %1, %0": "=r"(index): "rm"(b) );
273 return (Square) index;
276 FORCE_INLINE Square msb(Bitboard b) {
278 __asm__("bsrq %1, %0": "=r"(index): "rm"(b) );
279 return (Square) index;
284 FORCE_INLINE Square pop_lsb(Bitboard* b) {
285 const Square s = lsb(*b);
290 #else // if !defined(USE_BSFQ)
292 extern Square msb(Bitboard b);
293 extern Square lsb(Bitboard b);
294 extern Square pop_lsb(Bitboard* b);
298 #endif // !defined(BITBOARD_H_INCLUDED)