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 ThisAndAdjacentFilesBB[FILE_NB];
57 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
58 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
59 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
60 extern Bitboard DistanceRingsBB[SQUARE_NB][8];
61 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
62 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
63 extern Bitboard AttackSpanMask[COLOR_NB][SQUARE_NB];
64 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
66 const Bitboard WhiteSquares = 0x55AA55AA55AA55AAULL;
67 const Bitboard BlackSquares = 0xAA55AA55AA55AA55ULL;
69 /// Overloads of bitwise operators between a Bitboard and a Square for testing
70 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
72 inline Bitboard operator&(Bitboard b, Square s) {
73 return b & SquareBB[s];
76 inline Bitboard& operator|=(Bitboard& b, Square s) {
77 return b |= SquareBB[s];
80 inline Bitboard& operator^=(Bitboard& b, Square s) {
81 return b ^= SquareBB[s];
84 inline Bitboard operator|(Bitboard b, Square s) {
85 return b | SquareBB[s];
88 inline Bitboard operator^(Bitboard b, Square s) {
89 return b ^ SquareBB[s];
93 /// more_than_one() returns true if in 'b' there is more than one bit set
95 inline bool more_than_one(Bitboard b) {
100 /// rank_bb() and file_bb() take a file or a square as input and return
101 /// a bitboard representing all squares on the given file or rank.
103 inline Bitboard rank_bb(Rank r) {
107 inline Bitboard rank_bb(Square s) {
108 return RankBB[rank_of(s)];
111 inline Bitboard file_bb(File f) {
115 inline Bitboard file_bb(Square s) {
116 return FileBB[file_of(s)];
120 /// adjacent_files_bb takes a file as input and returns a bitboard representing
121 /// all squares on the adjacent files.
123 inline Bitboard adjacent_files_bb(File f) {
124 return AdjacentFilesBB[f];
128 /// this_and_adjacent_files_bb takes a file as input and returns a bitboard
129 /// representing all squares on the given and adjacent files.
131 inline Bitboard this_and_adjacent_files_bb(File f) {
132 return ThisAndAdjacentFilesBB[f];
136 /// in_front_bb() takes a color and a rank or square as input, and returns a
137 /// bitboard representing all the squares on all ranks in front of the rank
138 /// (or square), from the given color's point of view. For instance,
139 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
140 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
142 inline Bitboard in_front_bb(Color c, Rank r) {
143 return InFrontBB[c][r];
146 inline Bitboard in_front_bb(Color c, Square s) {
147 return InFrontBB[c][rank_of(s)];
151 /// between_bb returns a bitboard representing all squares between two squares.
152 /// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
153 /// square d5 and e6 set. If s1 and s2 are not on the same line, file or diagonal,
156 inline Bitboard between_bb(Square s1, Square s2) {
157 return BetweenBB[s1][s2];
161 /// forward_bb takes a color and a square as input, and returns a bitboard
162 /// representing all squares along the line in front of the square, from the
163 /// point of view of the given color. Definition of the table is:
164 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
166 inline Bitboard forward_bb(Color c, Square s) {
167 return ForwardBB[c][s];
171 /// passed_pawn_mask takes a color and a square as input, and returns a
172 /// bitboard mask which can be used to test if a pawn of the given color on
173 /// the given square is a passed pawn. Definition of the table is:
174 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(s)
176 inline Bitboard passed_pawn_mask(Color c, Square s) {
177 return PassedPawnMask[c][s];
181 /// attack_span_mask takes a color and a square as input, and returns a bitboard
182 /// representing all squares that can be attacked by a pawn of the given color
183 /// when it moves along its file starting from the given square. Definition is:
184 /// AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
186 inline Bitboard attack_span_mask(Color c, Square s) {
187 return AttackSpanMask[c][s];
191 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
192 /// either on a straight or on a diagonal line.
194 inline bool squares_aligned(Square s1, Square s2, Square s3) {
195 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
196 & ( SquareBB[s1] | SquareBB[s2] | SquareBB[s3]);
200 /// same_color_squares() returns a bitboard representing all squares with
201 /// the same color of the given square.
203 inline Bitboard same_color_squares(Square s) {
204 return Bitboard(0xAA55AA55AA55AA55ULL) & s ? 0xAA55AA55AA55AA55ULL
205 : ~0xAA55AA55AA55AA55ULL;
209 /// Functions for computing sliding attack bitboards. Function attacks_bb() takes
210 /// a square and a bitboard of occupied squares as input, and returns a bitboard
211 /// representing all squares attacked by Pt (bishop or rook) on the given square.
212 template<PieceType Pt>
213 FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
215 Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
216 Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
217 unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
220 return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
222 unsigned lo = unsigned(occ) & unsigned(Masks[s]);
223 unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
224 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
227 template<PieceType Pt>
228 inline Bitboard attacks_bb(Square s, Bitboard occ) {
229 return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
233 /// lsb()/msb() finds the least/most significant bit in a nonzero bitboard.
234 /// pop_lsb() finds and clears the least significant bit in a nonzero bitboard.
236 #if defined(USE_BSFQ)
238 # if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
240 FORCE_INLINE Square lsb(Bitboard b) {
242 _BitScanForward64(&index, b);
243 return (Square) index;
246 FORCE_INLINE Square msb(Bitboard b) {
248 _BitScanReverse64(&index, b);
249 return (Square) index;
252 # elif defined(__arm__)
254 FORCE_INLINE int lsb32(uint32_t v) {
255 __asm__("rbit %0, %1" : "=r"(v) : "r"(v));
256 return __builtin_clz(v);
259 FORCE_INLINE Square msb(Bitboard b) {
260 return (Square) (63 - __builtin_clzll(b));
263 FORCE_INLINE Square lsb(Bitboard b) {
264 return (Square) (uint32_t(b) ? lsb32(uint32_t(b)) : 32 + lsb32(uint32_t(b >> 32)));
269 FORCE_INLINE Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen
271 __asm__("bsfq %1, %0": "=r"(index): "rm"(b) );
272 return (Square) index;
275 FORCE_INLINE Square msb(Bitboard b) {
277 __asm__("bsrq %1, %0": "=r"(index): "rm"(b) );
278 return (Square) index;
283 FORCE_INLINE Square pop_lsb(Bitboard* b) {
284 const Square s = lsb(*b);
289 #else // if !defined(USE_BSFQ)
291 extern Square msb(Bitboard b);
292 extern Square lsb(Bitboard b);
293 extern Square pop_lsb(Bitboard* b);
297 #endif // !defined(BITBOARD_H_INCLUDED)