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
30 const std::string pretty(Bitboard b);
37 bool probe_kpk(Square wksq, Square wpsq, Square bksq, Color us);
41 const Bitboard FileABB = 0x0101010101010101ULL;
42 const Bitboard FileBBB = FileABB << 1;
43 const Bitboard FileCBB = FileABB << 2;
44 const Bitboard FileDBB = FileABB << 3;
45 const Bitboard FileEBB = FileABB << 4;
46 const Bitboard FileFBB = FileABB << 5;
47 const Bitboard FileGBB = FileABB << 6;
48 const Bitboard FileHBB = FileABB << 7;
50 const Bitboard Rank1BB = 0xFF;
51 const Bitboard Rank2BB = Rank1BB << (8 * 1);
52 const Bitboard Rank3BB = Rank1BB << (8 * 2);
53 const Bitboard Rank4BB = Rank1BB << (8 * 3);
54 const Bitboard Rank5BB = Rank1BB << (8 * 4);
55 const Bitboard Rank6BB = Rank1BB << (8 * 5);
56 const Bitboard Rank7BB = Rank1BB << (8 * 6);
57 const Bitboard Rank8BB = Rank1BB << (8 * 7);
61 extern Bitboard RMasks[SQUARE_NB];
62 extern Bitboard RMagics[SQUARE_NB];
63 extern Bitboard* RAttacks[SQUARE_NB];
64 extern unsigned RShifts[SQUARE_NB];
66 extern Bitboard BMasks[SQUARE_NB];
67 extern Bitboard BMagics[SQUARE_NB];
68 extern Bitboard* BAttacks[SQUARE_NB];
69 extern unsigned BShifts[SQUARE_NB];
71 extern Bitboard SquareBB[SQUARE_NB];
72 extern Bitboard FileBB[FILE_NB];
73 extern Bitboard RankBB[RANK_NB];
74 extern Bitboard AdjacentFilesBB[FILE_NB];
75 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
76 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
77 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
78 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
79 extern Bitboard DistanceRingsBB[SQUARE_NB][8];
80 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
81 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
82 extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
83 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
85 extern int SquareDistance[SQUARE_NB][SQUARE_NB];
87 const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
89 /// Overloads of bitwise operators between a Bitboard and a Square for testing
90 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
92 inline Bitboard operator&(Bitboard b, Square s) {
93 return b & SquareBB[s];
96 inline Bitboard& operator|=(Bitboard& b, Square s) {
97 return b |= SquareBB[s];
100 inline Bitboard& operator^=(Bitboard& b, Square s) {
101 return b ^= SquareBB[s];
104 inline Bitboard operator|(Bitboard b, Square s) {
105 return b | SquareBB[s];
108 inline Bitboard operator^(Bitboard b, Square s) {
109 return b ^ SquareBB[s];
112 inline bool more_than_one(Bitboard b) {
116 inline int square_distance(Square s1, Square s2) {
117 return SquareDistance[s1][s2];
120 inline int file_distance(Square s1, Square s2) {
121 return abs(file_of(s1) - file_of(s2));
124 inline int rank_distance(Square s1, Square s2) {
125 return abs(rank_of(s1) - rank_of(s2));
129 /// shift_bb() moves bitboard one step along direction Delta. Mainly for pawns.
131 template<Square Delta>
132 inline Bitboard shift_bb(Bitboard b) {
134 return Delta == DELTA_N ? b << 8 : Delta == DELTA_S ? b >> 8
135 : Delta == DELTA_NE ? (b & ~FileHBB) << 9 : Delta == DELTA_SE ? (b & ~FileHBB) >> 7
136 : Delta == DELTA_NW ? (b & ~FileABB) << 7 : Delta == DELTA_SW ? (b & ~FileABB) >> 9
141 /// rank_bb() and file_bb() take a file or a square as input and return
142 /// a bitboard representing all squares on the given file or rank.
144 inline Bitboard rank_bb(Rank r) {
148 inline Bitboard rank_bb(Square s) {
149 return RankBB[rank_of(s)];
152 inline Bitboard file_bb(File f) {
156 inline Bitboard file_bb(Square s) {
157 return FileBB[file_of(s)];
161 /// adjacent_files_bb() takes a file as input and returns a bitboard representing
162 /// all squares on the adjacent files.
164 inline Bitboard adjacent_files_bb(File f) {
165 return AdjacentFilesBB[f];
169 /// in_front_bb() takes a color and a rank as input, and returns a bitboard
170 /// representing all the squares on all ranks in front of the rank, from the
171 /// given color's point of view. For instance, in_front_bb(BLACK, RANK_3) will
172 /// give all squares on ranks 1 and 2.
174 inline Bitboard in_front_bb(Color c, Rank r) {
175 return InFrontBB[c][r];
179 /// between_bb() returns a bitboard representing all squares between two squares.
180 /// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
181 /// square d5 and e6 set. If s1 and s2 are not on the same rank, file or diagonal,
184 inline Bitboard between_bb(Square s1, Square s2) {
185 return BetweenBB[s1][s2];
189 /// forward_bb() takes a color and a square as input, and returns a bitboard
190 /// representing all squares along the line in front of the square, from the
191 /// point of view of the given color. Definition of the table is:
192 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
194 inline Bitboard forward_bb(Color c, Square s) {
195 return ForwardBB[c][s];
199 /// pawn_attack_span() takes a color and a square as input, and returns a bitboard
200 /// representing all squares that can be attacked by a pawn of the given color
201 /// when it moves along its file starting from the given square. Definition is:
202 /// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
204 inline Bitboard pawn_attack_span(Color c, Square s) {
205 return PawnAttackSpan[c][s];
209 /// passed_pawn_mask() takes a color and a square as input, and returns a
210 /// bitboard mask which can be used to test if a pawn of the given color on
211 /// the given square is a passed pawn. Definition of the table is:
212 /// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_bb(c, s)
214 inline Bitboard passed_pawn_mask(Color c, Square s) {
215 return PassedPawnMask[c][s];
219 /// squares_of_color() returns a bitboard representing all squares with the same
220 /// color of the given square.
222 inline Bitboard squares_of_color(Square s) {
223 return DarkSquares & s ? DarkSquares : ~DarkSquares;
227 /// aligned() returns true if the squares s1, s2 and s3 are aligned
228 /// either on a straight or on a diagonal line.
230 inline bool aligned(Square s1, Square s2, Square s3) {
231 return LineBB[s1][s2] & s3;
235 /// Functions for computing sliding attack bitboards. Function attacks_bb() takes
236 /// a square and a bitboard of occupied squares as input, and returns a bitboard
237 /// representing all squares attacked by Pt (bishop or rook) on the given square.
238 template<PieceType Pt>
239 FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
241 Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
242 Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
243 unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
246 return unsigned(_pext_u64(occ, Masks[s]));
249 return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
251 unsigned lo = unsigned(occ) & unsigned(Masks[s]);
252 unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
253 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
256 template<PieceType Pt>
257 inline Bitboard attacks_bb(Square s, Bitboard occ) {
258 return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
261 inline Bitboard attacks_bb(Piece pc, Square s, Bitboard occ) {
265 case BISHOP: return attacks_bb<BISHOP>(s, occ);
266 case ROOK : return attacks_bb<ROOK>(s, occ);
267 case QUEEN : return attacks_bb<BISHOP>(s, occ) | attacks_bb<ROOK>(s, occ);
268 default : return StepAttacksBB[pc][s];
272 /// lsb()/msb() finds the least/most significant bit in a non-zero bitboard.
273 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard.
277 # if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
279 FORCE_INLINE Square lsb(Bitboard b) {
281 _BitScanForward64(&idx, b);
285 FORCE_INLINE Square msb(Bitboard b) {
287 _BitScanReverse64(&idx, b);
291 # elif defined(__arm__)
293 FORCE_INLINE int lsb32(uint32_t v) {
294 __asm__("rbit %0, %1" : "=r"(v) : "r"(v));
295 return __builtin_clz(v);
298 FORCE_INLINE Square msb(Bitboard b) {
299 return (Square) (63 - __builtin_clzll(b));
302 FORCE_INLINE Square lsb(Bitboard b) {
303 return (Square) (uint32_t(b) ? lsb32(uint32_t(b)) : 32 + lsb32(uint32_t(b >> 32)));
308 FORCE_INLINE Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen
310 __asm__("bsfq %1, %0": "=r"(idx): "rm"(b) );
314 FORCE_INLINE Square msb(Bitboard b) {
316 __asm__("bsrq %1, %0": "=r"(idx): "rm"(b) );
322 FORCE_INLINE Square pop_lsb(Bitboard* b) {
323 const Square s = lsb(*b);
328 #else // if defined(USE_BSFQ)
330 extern Square msb(Bitboard b);
331 extern Square lsb(Bitboard b);
332 extern Square pop_lsb(Bitboard* b);
336 /// frontmost_sq() and backmost_sq() find the square corresponding to the
337 /// most/least advanced bit relative to the given color.
339 inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); }
340 inline Square backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); }
342 #endif // #ifndef BITBOARD_H_INCLUDED