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/>.
22 #if !defined(BITBOARD_H_INCLUDED)
23 #define BITBOARD_H_INCLUDED
35 //// Constants and variables
38 const Bitboard EmptyBoardBB = 0;
40 const Bitboard FileABB = 0x0101010101010101ULL;
41 const Bitboard FileBBB = FileABB << 1;
42 const Bitboard FileCBB = FileABB << 2;
43 const Bitboard FileDBB = FileABB << 3;
44 const Bitboard FileEBB = FileABB << 4;
45 const Bitboard FileFBB = FileABB << 5;
46 const Bitboard FileGBB = FileABB << 6;
47 const Bitboard FileHBB = FileABB << 7;
49 const Bitboard Rank1BB = 0xFF;
50 const Bitboard Rank2BB = Rank1BB << (8 * 1);
51 const Bitboard Rank3BB = Rank1BB << (8 * 2);
52 const Bitboard Rank4BB = Rank1BB << (8 * 3);
53 const Bitboard Rank5BB = Rank1BB << (8 * 4);
54 const Bitboard Rank6BB = Rank1BB << (8 * 5);
55 const Bitboard Rank7BB = Rank1BB << (8 * 6);
56 const Bitboard Rank8BB = Rank1BB << (8 * 7);
58 extern const Bitboard SquaresByColorBB[2];
59 extern const Bitboard FileBB[8];
60 extern const Bitboard NeighboringFilesBB[8];
61 extern const Bitboard ThisAndNeighboringFilesBB[8];
62 extern const Bitboard RankBB[8];
63 extern const Bitboard RelativeRankBB[2][8];
64 extern const Bitboard InFrontBB[2][8];
66 extern Bitboard SetMaskBB[65];
67 extern Bitboard ClearMaskBB[65];
69 extern Bitboard StepAttackBB[16][64];
70 extern Bitboard RayBB[64][8];
71 extern Bitboard BetweenBB[64][64];
73 extern Bitboard SquaresInFrontMask[2][64];
74 extern Bitboard PassedPawnMask[2][64];
75 extern Bitboard AttackSpanMask[2][64];
77 extern const uint64_t RMult[64];
78 extern const int RShift[64];
79 extern Bitboard RMask[64];
80 extern int RAttackIndex[64];
81 extern Bitboard RAttacks[0x19000];
83 extern const uint64_t BMult[64];
84 extern const int BShift[64];
85 extern Bitboard BMask[64];
86 extern int BAttackIndex[64];
87 extern Bitboard BAttacks[0x1480];
89 extern Bitboard BishopPseudoAttacks[64];
90 extern Bitboard RookPseudoAttacks[64];
91 extern Bitboard QueenPseudoAttacks[64];
93 extern uint8_t BitCount8Bit[256];
100 /// Functions for testing whether a given bit is set in a bitboard, and for
101 /// setting and clearing bits.
103 inline Bitboard bit_is_set(Bitboard b, Square s) {
104 return b & SetMaskBB[s];
107 inline void set_bit(Bitboard *b, Square s) {
111 inline void clear_bit(Bitboard *b, Square s) {
112 *b &= ClearMaskBB[s];
116 /// Functions used to update a bitboard after a move. This is faster
117 /// then calling a sequence of clear_bit() + set_bit()
119 inline Bitboard make_move_bb(Square from, Square to) {
120 return SetMaskBB[from] | SetMaskBB[to];
123 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
127 /// rank_bb() and file_bb() take a file or a square as input, and return
128 /// a bitboard representing all squares on the given file or rank.
130 inline Bitboard rank_bb(Rank r) {
134 inline Bitboard rank_bb(Square s) {
135 return rank_bb(square_rank(s));
138 inline Bitboard file_bb(File f) {
142 inline Bitboard file_bb(Square s) {
143 return file_bb(square_file(s));
147 /// neighboring_files_bb takes a file or a square as input, and returns a
148 /// bitboard representing all squares on the neighboring files.
150 inline Bitboard neighboring_files_bb(File f) {
151 return NeighboringFilesBB[f];
154 inline Bitboard neighboring_files_bb(Square s) {
155 return NeighboringFilesBB[square_file(s)];
159 /// this_and_neighboring_files_bb takes a file or a square as input, and
160 /// returns a bitboard representing all squares on the given and neighboring
163 inline Bitboard this_and_neighboring_files_bb(File f) {
164 return ThisAndNeighboringFilesBB[f];
167 inline Bitboard this_and_neighboring_files_bb(Square s) {
168 return ThisAndNeighboringFilesBB[square_file(s)];
172 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
173 /// representing all squares on the given rank from the given color's point of
174 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
175 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
178 inline Bitboard relative_rank_bb(Color c, Rank r) {
179 return RelativeRankBB[c][r];
183 /// in_front_bb() takes a color and a rank or square as input, and returns a
184 /// bitboard representing all the squares on all ranks in front of the rank
185 /// (or square), from the given color's point of view. For instance,
186 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
187 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
189 inline Bitboard in_front_bb(Color c, Rank r) {
190 return InFrontBB[c][r];
193 inline Bitboard in_front_bb(Color c, Square s) {
194 return InFrontBB[c][square_rank(s)];
198 /// behind_bb() takes a color and a rank or square as input, and returns a
199 /// bitboard representing all the squares on all ranks behind of the rank
200 /// (or square), from the given color's point of view.
202 inline Bitboard behind_bb(Color c, Rank r) {
203 return InFrontBB[opposite_color(c)][r];
206 inline Bitboard behind_bb(Color c, Square s) {
207 return InFrontBB[opposite_color(c)][square_rank(s)];
211 /// ray_bb() gives a bitboard representing all squares along the ray in a
212 /// given direction from a given square.
214 inline Bitboard ray_bb(Square s, SignedDirection d) {
219 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
220 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
221 /// bitboard of occupied squares as input, and return a bitboard representing
222 /// all squares attacked by a rook, bishop or queen on the given square.
224 #if defined(IS_64BIT)
226 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
227 Bitboard b = blockers & RMask[s];
228 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
231 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
232 Bitboard b = blockers & BMask[s];
233 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
236 #else // if !defined(IS_64BIT)
238 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
239 Bitboard b = blockers & RMask[s];
240 return RAttacks[RAttackIndex[s] +
241 (unsigned(int(b) * int(RMult[s]) ^
242 int(b >> 32) * int(RMult[s] >> 32))
246 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
247 Bitboard b = blockers & BMask[s];
248 return BAttacks[BAttackIndex[s] +
249 (unsigned(int(b) * int(BMult[s]) ^
250 int(b >> 32) * int(BMult[s] >> 32))
256 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
257 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
261 /// squares_between returns a bitboard representing all squares between
262 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
263 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
264 /// on the same line, file or diagonal, EmptyBoardBB is returned.
266 inline Bitboard squares_between(Square s1, Square s2) {
267 return BetweenBB[s1][s2];
271 /// squares_in_front_of takes a color and a square as input, and returns a
272 /// bitboard representing all squares along the line in front of the square,
273 /// from the point of view of the given color. Definition of the table is:
274 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
276 inline Bitboard squares_in_front_of(Color c, Square s) {
277 return SquaresInFrontMask[c][s];
281 /// squares_behind is similar to squares_in_front, but returns the squares
282 /// behind the square instead of in front of the square.
284 inline Bitboard squares_behind(Color c, Square s) {
285 return SquaresInFrontMask[opposite_color(c)][s];
289 /// passed_pawn_mask takes a color and a square as input, and returns a
290 /// bitboard mask which can be used to test if a pawn of the given color on
291 /// the given square is a passed pawn. Definition of the table is:
292 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
294 inline Bitboard passed_pawn_mask(Color c, Square s) {
295 return PassedPawnMask[c][s];
299 /// attack_span_mask takes a color and a square as input, and returns a bitboard
300 /// representing all squares that can be attacked by a pawn of the given color
301 /// when it moves along its file starting from the given square. Definition is:
302 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
304 inline Bitboard attack_span_mask(Color c, Square s) {
305 return AttackSpanMask[c][s];
309 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
310 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
311 /// nonzero bitboard.
313 #if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
315 inline Square first_1(Bitboard b) {
317 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
318 return (Square)(dummy);
321 inline Square pop_1st_bit(Bitboard* b) {
322 const Square s = first_1(*b);
327 #else // if !defined(USE_BSFQ)
329 extern Square first_1(Bitboard b);
330 extern Square pop_1st_bit(Bitboard* b);
339 extern void print_bitboard(Bitboard b);
340 extern void init_bitboards();
343 #endif // !defined(BITBOARD_H_INCLUDED)