2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 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
28 const Bitboard EmptyBoardBB = 0;
30 const Bitboard FileABB = 0x0101010101010101ULL;
31 const Bitboard FileBBB = FileABB << 1;
32 const Bitboard FileCBB = FileABB << 2;
33 const Bitboard FileDBB = FileABB << 3;
34 const Bitboard FileEBB = FileABB << 4;
35 const Bitboard FileFBB = FileABB << 5;
36 const Bitboard FileGBB = FileABB << 6;
37 const Bitboard FileHBB = FileABB << 7;
39 const Bitboard Rank1BB = 0xFF;
40 const Bitboard Rank2BB = Rank1BB << (8 * 1);
41 const Bitboard Rank3BB = Rank1BB << (8 * 2);
42 const Bitboard Rank4BB = Rank1BB << (8 * 3);
43 const Bitboard Rank5BB = Rank1BB << (8 * 4);
44 const Bitboard Rank6BB = Rank1BB << (8 * 5);
45 const Bitboard Rank7BB = Rank1BB << (8 * 6);
46 const Bitboard Rank8BB = Rank1BB << (8 * 7);
48 extern const Bitboard SquaresByColorBB[2];
49 extern const Bitboard FileBB[8];
50 extern const Bitboard NeighboringFilesBB[8];
51 extern const Bitboard ThisAndNeighboringFilesBB[8];
52 extern const Bitboard RankBB[8];
53 extern const Bitboard RelativeRankBB[2][8];
54 extern const Bitboard InFrontBB[2][8];
56 extern Bitboard SetMaskBB[65];
57 extern Bitboard ClearMaskBB[65];
59 extern Bitboard NonSlidingAttacksBB[16][64];
60 extern Bitboard BetweenBB[64][64];
62 extern Bitboard SquaresInFrontMask[2][64];
63 extern Bitboard PassedPawnMask[2][64];
64 extern Bitboard AttackSpanMask[2][64];
66 extern const uint64_t RMult[64];
67 extern const int RShift[64];
68 extern Bitboard RMask[64];
69 extern int RAttackIndex[64];
70 extern Bitboard RAttacks[0x19000];
72 extern const uint64_t BMult[64];
73 extern const int BShift[64];
74 extern Bitboard BMask[64];
75 extern int BAttackIndex[64];
76 extern Bitboard BAttacks[0x1480];
78 extern Bitboard BishopPseudoAttacks[64];
79 extern Bitboard RookPseudoAttacks[64];
80 extern Bitboard QueenPseudoAttacks[64];
82 extern uint8_t BitCount8Bit[256];
85 /// Functions for testing whether a given bit is set in a bitboard, and for
86 /// setting and clearing bits.
88 inline Bitboard bit_is_set(Bitboard b, Square s) {
89 return b & SetMaskBB[s];
92 inline void set_bit(Bitboard *b, Square s) {
96 inline void clear_bit(Bitboard *b, Square s) {
101 /// Functions used to update a bitboard after a move. This is faster
102 /// then calling a sequence of clear_bit() + set_bit()
104 inline Bitboard make_move_bb(Square from, Square to) {
105 return SetMaskBB[from] | SetMaskBB[to];
108 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
113 /// rank_bb() and file_bb() take a file or a square as input and return
114 /// a bitboard representing all squares on the given file or rank.
116 inline Bitboard rank_bb(Rank r) {
120 inline Bitboard rank_bb(Square s) {
121 return RankBB[square_rank(s)];
124 inline Bitboard file_bb(File f) {
128 inline Bitboard file_bb(Square s) {
129 return FileBB[square_file(s)];
133 /// neighboring_files_bb takes a file or a square as input and returns a
134 /// bitboard representing all squares on the neighboring files.
136 inline Bitboard neighboring_files_bb(File f) {
137 return NeighboringFilesBB[f];
140 inline Bitboard neighboring_files_bb(Square s) {
141 return NeighboringFilesBB[square_file(s)];
145 /// this_and_neighboring_files_bb takes a file or a square as input and returns
146 /// a bitboard representing all squares on the given and neighboring files.
148 inline Bitboard this_and_neighboring_files_bb(File f) {
149 return ThisAndNeighboringFilesBB[f];
152 inline Bitboard this_and_neighboring_files_bb(Square s) {
153 return ThisAndNeighboringFilesBB[square_file(s)];
157 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
158 /// representing all squares on the given rank from the given color's point of
159 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
160 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
163 inline Bitboard relative_rank_bb(Color c, Rank r) {
164 return RelativeRankBB[c][r];
168 /// in_front_bb() takes a color and a rank or square as input, and returns a
169 /// bitboard representing all the squares on all ranks in front of the rank
170 /// (or square), from the given color's point of view. For instance,
171 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
172 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
174 inline Bitboard in_front_bb(Color c, Rank r) {
175 return InFrontBB[c][r];
178 inline Bitboard in_front_bb(Color c, Square s) {
179 return InFrontBB[c][square_rank(s)];
183 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
184 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
185 /// bitboard of occupied squares as input, and return a bitboard representing
186 /// all squares attacked by a rook, bishop or queen on the given square.
188 #if defined(IS_64BIT)
190 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
191 Bitboard b = blockers & RMask[s];
192 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
195 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
196 Bitboard b = blockers & BMask[s];
197 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
200 #else // if !defined(IS_64BIT)
202 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
203 Bitboard b = blockers & RMask[s];
204 return RAttacks[RAttackIndex[s] +
205 (unsigned(int(b) * int(RMult[s]) ^
206 int(b >> 32) * int(RMult[s] >> 32))
210 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
211 Bitboard b = blockers & BMask[s];
212 return BAttacks[BAttackIndex[s] +
213 (unsigned(int(b) * int(BMult[s]) ^
214 int(b >> 32) * int(BMult[s] >> 32))
220 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
221 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
225 /// squares_between returns a bitboard representing all squares between
226 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
227 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
228 /// on the same line, file or diagonal, EmptyBoardBB is returned.
230 inline Bitboard squares_between(Square s1, Square s2) {
231 return BetweenBB[s1][s2];
235 /// squares_in_front_of takes a color and a square as input, and returns a
236 /// bitboard representing all squares along the line in front of the square,
237 /// from the point of view of the given color. Definition of the table is:
238 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
240 inline Bitboard squares_in_front_of(Color c, Square s) {
241 return SquaresInFrontMask[c][s];
245 /// passed_pawn_mask takes a color and a square as input, and returns a
246 /// bitboard mask which can be used to test if a pawn of the given color on
247 /// the given square is a passed pawn. Definition of the table is:
248 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
250 inline Bitboard passed_pawn_mask(Color c, Square s) {
251 return PassedPawnMask[c][s];
255 /// attack_span_mask takes a color and a square as input, and returns a bitboard
256 /// representing all squares that can be attacked by a pawn of the given color
257 /// when it moves along its file starting from the given square. Definition is:
258 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
260 inline Bitboard attack_span_mask(Color c, Square s) {
261 return AttackSpanMask[c][s];
265 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
266 /// either on a straight or on a diagonal line.
268 inline bool squares_aligned(Square s1, Square s2, Square s3) {
269 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
270 & ((1ULL << s1) | (1ULL << s2) | (1ULL << s3));
274 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
275 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
276 /// nonzero bitboard.
278 #if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
280 inline Square first_1(Bitboard b) {
282 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
283 return (Square)(dummy);
286 inline Square pop_1st_bit(Bitboard* b) {
287 const Square s = first_1(*b);
292 #else // if !defined(USE_BSFQ)
294 extern Square first_1(Bitboard b);
295 extern Square pop_1st_bit(Bitboard* b);
300 extern void print_bitboard(Bitboard b);
301 extern void init_bitboards();
303 #endif // !defined(BITBOARD_H_INCLUDED)