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);
62 extern Bitboard RMasks[SQUARE_NB];
63 extern Bitboard RMagics[SQUARE_NB];
64 extern Bitboard* RAttacks[SQUARE_NB];
65 extern unsigned RShifts[SQUARE_NB];
67 extern Bitboard BMasks[SQUARE_NB];
68 extern Bitboard BMagics[SQUARE_NB];
69 extern Bitboard* BAttacks[SQUARE_NB];
70 extern unsigned BShifts[SQUARE_NB];
72 extern Bitboard SquareBB[SQUARE_NB];
73 extern Bitboard FileBB[FILE_NB];
74 extern Bitboard RankBB[RANK_NB];
75 extern Bitboard AdjacentFilesBB[FILE_NB];
76 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
77 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
78 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
79 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
80 extern Bitboard DistanceRingsBB[SQUARE_NB][8];
81 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
82 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
83 extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
84 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
86 extern int SquareDistance[SQUARE_NB][SQUARE_NB];
88 const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
90 /// Overloads of bitwise operators between a Bitboard and a Square for testing
91 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
93 inline Bitboard operator&(Bitboard b, Square s) {
94 return b & SquareBB[s];
97 inline Bitboard& operator|=(Bitboard& b, Square s) {
98 return b |= SquareBB[s];
101 inline Bitboard& operator^=(Bitboard& b, Square s) {
102 return b ^= SquareBB[s];
105 inline Bitboard operator|(Bitboard b, Square s) {
106 return b | SquareBB[s];
109 inline Bitboard operator^(Bitboard b, Square s) {
110 return b ^ SquareBB[s];
113 inline bool more_than_one(Bitboard b) {
117 inline int square_distance(Square s1, Square s2) {
118 return SquareDistance[s1][s2];
121 inline int file_distance(Square s1, Square s2) {
122 return dist(file_of(s1), file_of(s2));
125 inline int rank_distance(Square s1, Square s2) {
126 return dist(rank_of(s1), rank_of(s2));
130 /// shift_bb() moves bitboard one step along direction Delta. Mainly for pawns.
132 template<Square Delta>
133 inline Bitboard shift_bb(Bitboard b) {
135 return Delta == DELTA_N ? b << 8 : Delta == DELTA_S ? b >> 8
136 : Delta == DELTA_NE ? (b & ~FileHBB) << 9 : Delta == DELTA_SE ? (b & ~FileHBB) >> 7
137 : Delta == DELTA_NW ? (b & ~FileABB) << 7 : Delta == DELTA_SW ? (b & ~FileABB) >> 9
142 /// rank_bb() and file_bb() take a file or a square as input and return
143 /// a bitboard representing all squares on the given file or rank.
145 inline Bitboard rank_bb(Rank r) {
149 inline Bitboard rank_bb(Square s) {
150 return RankBB[rank_of(s)];
153 inline Bitboard file_bb(File f) {
157 inline Bitboard file_bb(Square s) {
158 return FileBB[file_of(s)];
162 /// adjacent_files_bb() takes a file as input and returns a bitboard representing
163 /// all squares on the adjacent files.
165 inline Bitboard adjacent_files_bb(File f) {
166 return AdjacentFilesBB[f];
170 /// in_front_bb() takes a color and a rank as input, and returns a bitboard
171 /// representing all the squares on all ranks in front of the rank, from the
172 /// given color's point of view. For instance, in_front_bb(BLACK, RANK_3) will
173 /// give all squares on ranks 1 and 2.
175 inline Bitboard in_front_bb(Color c, Rank r) {
176 return InFrontBB[c][r];
180 /// between_bb() returns a bitboard representing all squares between two squares.
181 /// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
182 /// square d5 and e6 set. If s1 and s2 are not on the same rank, file or diagonal,
185 inline Bitboard between_bb(Square s1, Square s2) {
186 return BetweenBB[s1][s2];
190 /// forward_bb() takes a color and a square as input, and returns a bitboard
191 /// representing all squares along the line in front of the square, from the
192 /// point of view of the given color. Definition of the table is:
193 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
195 inline Bitboard forward_bb(Color c, Square s) {
196 return ForwardBB[c][s];
200 /// pawn_attack_span() takes a color and a square as input, and returns a bitboard
201 /// representing all squares that can be attacked by a pawn of the given color
202 /// when it moves along its file starting from the given square. Definition is:
203 /// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
205 inline Bitboard pawn_attack_span(Color c, Square s) {
206 return PawnAttackSpan[c][s];
210 /// passed_pawn_mask() takes a color and a square as input, and returns a
211 /// bitboard mask which can be used to test if a pawn of the given color on
212 /// the given square is a passed pawn. Definition of the table is:
213 /// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_bb(c, s)
215 inline Bitboard passed_pawn_mask(Color c, Square s) {
216 return PassedPawnMask[c][s];
220 /// squares_of_color() returns a bitboard representing all squares with the same
221 /// color of the given square.
223 inline Bitboard squares_of_color(Square s) {
224 return DarkSquares & s ? DarkSquares : ~DarkSquares;
228 /// aligned() returns true if the squares s1, s2 and s3 are aligned
229 /// either on a straight or on a diagonal line.
231 inline bool aligned(Square s1, Square s2, Square s3) {
232 return LineBB[s1][s2] & s3;
236 /// Functions for computing sliding attack bitboards. Function attacks_bb() takes
237 /// a square and a bitboard of occupied squares as input, and returns a bitboard
238 /// representing all squares attacked by Pt (bishop or rook) on the given square.
239 template<PieceType Pt>
240 FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
242 Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
243 Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
244 unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
247 return unsigned(_pext_u64(occ, Masks[s]));
250 return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
252 unsigned lo = unsigned(occ) & unsigned(Masks[s]);
253 unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
254 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
257 template<PieceType Pt>
258 inline Bitboard attacks_bb(Square s, Bitboard occ) {
259 return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
262 inline Bitboard attacks_bb(Piece pc, Square s, Bitboard occ) {
266 case BISHOP: return attacks_bb<BISHOP>(s, occ);
267 case ROOK : return attacks_bb<ROOK>(s, occ);
268 case QUEEN : return attacks_bb<BISHOP>(s, occ) | attacks_bb<ROOK>(s, occ);
269 default : return StepAttacksBB[pc][s];
273 /// lsb()/msb() finds the least/most significant bit in a non-zero bitboard.
274 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard.
278 # if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
280 FORCE_INLINE Square lsb(Bitboard b) {
282 _BitScanForward64(&idx, b);
286 FORCE_INLINE Square msb(Bitboard b) {
288 _BitScanReverse64(&idx, b);
292 # elif defined(__arm__)
294 FORCE_INLINE int lsb32(uint32_t v) {
295 __asm__("rbit %0, %1" : "=r"(v) : "r"(v));
296 return __builtin_clz(v);
299 FORCE_INLINE Square msb(Bitboard b) {
300 return (Square) (63 - __builtin_clzll(b));
303 FORCE_INLINE Square lsb(Bitboard b) {
304 return (Square) (uint32_t(b) ? lsb32(uint32_t(b)) : 32 + lsb32(uint32_t(b >> 32)));
309 FORCE_INLINE Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen
311 __asm__("bsfq %1, %0": "=r"(idx): "rm"(b) );
315 FORCE_INLINE Square msb(Bitboard b) {
317 __asm__("bsrq %1, %0": "=r"(idx): "rm"(b) );
323 FORCE_INLINE Square pop_lsb(Bitboard* b) {
324 const Square s = lsb(*b);
329 #else // if defined(USE_BSFQ)
331 extern Square msb(Bitboard b);
332 extern Square lsb(Bitboard b);
333 extern Square pop_lsb(Bitboard* b);
337 /// frontmost_sq() and backmost_sq() find the square corresponding to the
338 /// most/least advanced bit relative to the given color.
340 inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); }
341 inline Square backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); }
343 #endif // #ifndef BITBOARD_H_INCLUDED