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
26 const Bitboard EmptyBoardBB = 0;
28 const Bitboard FileABB = 0x0101010101010101ULL;
29 const Bitboard FileBBB = FileABB << 1;
30 const Bitboard FileCBB = FileABB << 2;
31 const Bitboard FileDBB = FileABB << 3;
32 const Bitboard FileEBB = FileABB << 4;
33 const Bitboard FileFBB = FileABB << 5;
34 const Bitboard FileGBB = FileABB << 6;
35 const Bitboard FileHBB = FileABB << 7;
37 const Bitboard Rank1BB = 0xFF;
38 const Bitboard Rank2BB = Rank1BB << (8 * 1);
39 const Bitboard Rank3BB = Rank1BB << (8 * 2);
40 const Bitboard Rank4BB = Rank1BB << (8 * 3);
41 const Bitboard Rank5BB = Rank1BB << (8 * 4);
42 const Bitboard Rank6BB = Rank1BB << (8 * 5);
43 const Bitboard Rank7BB = Rank1BB << (8 * 6);
44 const Bitboard Rank8BB = Rank1BB << (8 * 7);
46 extern Bitboard SquaresByColorBB[2];
47 extern Bitboard FileBB[8];
48 extern Bitboard NeighboringFilesBB[8];
49 extern Bitboard ThisAndNeighboringFilesBB[8];
50 extern Bitboard RankBB[8];
51 extern Bitboard InFrontBB[2][8];
53 extern Bitboard SetMaskBB[65];
54 extern Bitboard ClearMaskBB[65];
56 extern Bitboard StepAttacksBB[16][64];
57 extern Bitboard BetweenBB[64][64];
59 extern Bitboard SquaresInFrontMask[2][64];
60 extern Bitboard PassedPawnMask[2][64];
61 extern Bitboard AttackSpanMask[2][64];
63 extern const uint64_t RMult[64];
64 extern const int RShift[64];
65 extern Bitboard RMask[64];
66 extern int RAttackIndex[64];
67 extern Bitboard RAttacks[0x19000];
69 extern const uint64_t BMult[64];
70 extern const int BShift[64];
71 extern Bitboard BMask[64];
72 extern int BAttackIndex[64];
73 extern Bitboard BAttacks[0x1480];
75 extern Bitboard BishopPseudoAttacks[64];
76 extern Bitboard RookPseudoAttacks[64];
77 extern Bitboard QueenPseudoAttacks[64];
79 extern uint8_t BitCount8Bit[256];
82 /// Functions for testing whether a given bit is set in a bitboard, and for
83 /// setting and clearing bits.
85 inline Bitboard bit_is_set(Bitboard b, Square s) {
86 return b & SetMaskBB[s];
89 inline void set_bit(Bitboard *b, Square s) {
93 inline void clear_bit(Bitboard *b, Square s) {
98 /// Functions used to update a bitboard after a move. This is faster
99 /// then calling a sequence of clear_bit() + set_bit()
101 inline Bitboard make_move_bb(Square from, Square to) {
102 return SetMaskBB[from] | SetMaskBB[to];
105 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
110 /// rank_bb() and file_bb() take a file or a square as input and return
111 /// a bitboard representing all squares on the given file or rank.
113 inline Bitboard rank_bb(Rank r) {
117 inline Bitboard rank_bb(Square s) {
118 return RankBB[square_rank(s)];
121 inline Bitboard file_bb(File f) {
125 inline Bitboard file_bb(Square s) {
126 return FileBB[square_file(s)];
130 /// neighboring_files_bb takes a file or a square as input and returns a
131 /// bitboard representing all squares on the neighboring files.
133 inline Bitboard neighboring_files_bb(File f) {
134 return NeighboringFilesBB[f];
137 inline Bitboard neighboring_files_bb(Square s) {
138 return NeighboringFilesBB[square_file(s)];
142 /// this_and_neighboring_files_bb takes a file or a square as input and returns
143 /// a bitboard representing all squares on the given and neighboring files.
145 inline Bitboard this_and_neighboring_files_bb(File f) {
146 return ThisAndNeighboringFilesBB[f];
149 inline Bitboard this_and_neighboring_files_bb(Square s) {
150 return ThisAndNeighboringFilesBB[square_file(s)];
154 /// in_front_bb() takes a color and a rank or square as input, and returns a
155 /// bitboard representing all the squares on all ranks in front of the rank
156 /// (or square), from the given color's point of view. For instance,
157 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
158 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
160 inline Bitboard in_front_bb(Color c, Rank r) {
161 return InFrontBB[c][r];
164 inline Bitboard in_front_bb(Color c, Square s) {
165 return InFrontBB[c][square_rank(s)];
169 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
170 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
171 /// bitboard of occupied squares as input, and return a bitboard representing
172 /// all squares attacked by a rook, bishop or queen on the given square.
174 #if defined(IS_64BIT)
176 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
177 Bitboard b = blockers & RMask[s];
178 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
181 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
182 Bitboard b = blockers & BMask[s];
183 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
186 #else // if !defined(IS_64BIT)
188 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
189 Bitboard b = blockers & RMask[s];
190 return RAttacks[RAttackIndex[s] +
191 (unsigned(int(b) * int(RMult[s]) ^ int(b >> 32) * int(RMult[s] >> 32)) >> RShift[s])];
194 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
195 Bitboard b = blockers & BMask[s];
196 return BAttacks[BAttackIndex[s] +
197 (unsigned(int(b) * int(BMult[s]) ^ int(b >> 32) * int(BMult[s] >> 32)) >> BShift[s])];
202 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
203 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
207 /// squares_between returns a bitboard representing all squares between
208 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
209 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
210 /// on the same line, file or diagonal, EmptyBoardBB is returned.
212 inline Bitboard squares_between(Square s1, Square s2) {
213 return BetweenBB[s1][s2];
217 /// squares_in_front_of takes a color and a square as input, and returns a
218 /// bitboard representing all squares along the line in front of the square,
219 /// from the point of view of the given color. Definition of the table is:
220 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
222 inline Bitboard squares_in_front_of(Color c, Square s) {
223 return SquaresInFrontMask[c][s];
227 /// passed_pawn_mask takes a color and a square as input, and returns a
228 /// bitboard mask which can be used to test if a pawn of the given color on
229 /// the given square is a passed pawn. Definition of the table is:
230 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
232 inline Bitboard passed_pawn_mask(Color c, Square s) {
233 return PassedPawnMask[c][s];
237 /// attack_span_mask takes a color and a square as input, and returns a bitboard
238 /// representing all squares that can be attacked by a pawn of the given color
239 /// when it moves along its file starting from the given square. Definition is:
240 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
242 inline Bitboard attack_span_mask(Color c, Square s) {
243 return AttackSpanMask[c][s];
247 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
248 /// either on a straight or on a diagonal line.
250 inline bool squares_aligned(Square s1, Square s2, Square s3) {
251 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
252 & ((1ULL << s1) | (1ULL << s2) | (1ULL << s3));
256 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
257 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
258 /// nonzero bitboard.
260 #if defined(USE_BSFQ)
262 #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
264 FORCE_INLINE Square first_1(Bitboard b) {
266 _BitScanForward64(&index, b);
267 return (Square) index;
271 FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
273 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
274 return (Square) dummy;
278 FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
279 const Square s = first_1(*b);
284 #else // if !defined(USE_BSFQ)
286 extern Square first_1(Bitboard b);
287 extern Square pop_1st_bit(Bitboard* b);
292 extern void print_bitboard(Bitboard b);
293 extern void init_bitboards();
295 #endif // !defined(BITBOARD_H_INCLUDED)