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 Bitboard BishopPseudoAttacks[64];
64 extern Bitboard RookPseudoAttacks[64];
65 extern Bitboard QueenPseudoAttacks[64];
67 extern uint8_t BitCount8Bit[256];
76 extern Magics RMagics[64];
77 extern Magics BMagics[64];
80 /// Functions for testing whether a given bit is set in a bitboard, and for
81 /// setting and clearing bits.
83 inline Bitboard bit_is_set(Bitboard b, Square s) {
84 return b & SetMaskBB[s];
87 inline void set_bit(Bitboard *b, Square s) {
91 inline void clear_bit(Bitboard *b, Square s) {
96 /// Functions used to update a bitboard after a move. This is faster
97 /// then calling a sequence of clear_bit() + set_bit()
99 inline Bitboard make_move_bb(Square from, Square to) {
100 return SetMaskBB[from] | SetMaskBB[to];
103 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
108 /// rank_bb() and file_bb() take a file or a square as input and return
109 /// a bitboard representing all squares on the given file or rank.
111 inline Bitboard rank_bb(Rank r) {
115 inline Bitboard rank_bb(Square s) {
116 return RankBB[square_rank(s)];
119 inline Bitboard file_bb(File f) {
123 inline Bitboard file_bb(Square s) {
124 return FileBB[square_file(s)];
128 /// neighboring_files_bb takes a file or a square as input and returns a
129 /// bitboard representing all squares on the neighboring files.
131 inline Bitboard neighboring_files_bb(File f) {
132 return NeighboringFilesBB[f];
135 inline Bitboard neighboring_files_bb(Square s) {
136 return NeighboringFilesBB[square_file(s)];
140 /// this_and_neighboring_files_bb takes a file or a square as input and returns
141 /// a bitboard representing all squares on the given and neighboring files.
143 inline Bitboard this_and_neighboring_files_bb(File f) {
144 return ThisAndNeighboringFilesBB[f];
147 inline Bitboard this_and_neighboring_files_bb(Square s) {
148 return ThisAndNeighboringFilesBB[square_file(s)];
152 /// in_front_bb() takes a color and a rank or square as input, and returns a
153 /// bitboard representing all the squares on all ranks in front of the rank
154 /// (or square), from the given color's point of view. For instance,
155 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
156 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
158 inline Bitboard in_front_bb(Color c, Rank r) {
159 return InFrontBB[c][r];
162 inline Bitboard in_front_bb(Color c, Square s) {
163 return InFrontBB[c][square_rank(s)];
167 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
168 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
169 /// bitboard of occupied squares as input, and return a bitboard representing
170 /// all squares attacked by a rook, bishop or queen on the given square.
172 #if defined(IS_64BIT)
174 inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
175 const Magics& m = RMagics[s];
176 return m.attacks[((occ & m.mask) * m.mult) >> m.shift];
179 inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
180 const Magics& m = BMagics[s];
181 return m.attacks[((occ & m.mask) * m.mult) >> m.shift];
184 #else // if !defined(IS_64BIT)
186 inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
187 const Magics& m = RMagics[s];
188 Bitboard b = occ & m.mask;
189 return m.attacks[(unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift];
192 inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
193 const Magics& m = BMagics[s];
194 Bitboard b = occ & m.mask;
195 return m.attacks[(unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift];
200 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
201 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
205 /// squares_between returns a bitboard representing all squares between
206 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
207 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
208 /// on the same line, file or diagonal, EmptyBoardBB is returned.
210 inline Bitboard squares_between(Square s1, Square s2) {
211 return BetweenBB[s1][s2];
215 /// squares_in_front_of takes a color and a square as input, and returns a
216 /// bitboard representing all squares along the line in front of the square,
217 /// from the point of view of the given color. Definition of the table is:
218 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
220 inline Bitboard squares_in_front_of(Color c, Square s) {
221 return SquaresInFrontMask[c][s];
225 /// passed_pawn_mask takes a color and a square as input, and returns a
226 /// bitboard mask which can be used to test if a pawn of the given color on
227 /// the given square is a passed pawn. Definition of the table is:
228 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
230 inline Bitboard passed_pawn_mask(Color c, Square s) {
231 return PassedPawnMask[c][s];
235 /// attack_span_mask takes a color and a square as input, and returns a bitboard
236 /// representing all squares that can be attacked by a pawn of the given color
237 /// when it moves along its file starting from the given square. Definition is:
238 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
240 inline Bitboard attack_span_mask(Color c, Square s) {
241 return AttackSpanMask[c][s];
245 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
246 /// either on a straight or on a diagonal line.
248 inline bool squares_aligned(Square s1, Square s2, Square s3) {
249 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
250 & ((1ULL << s1) | (1ULL << s2) | (1ULL << s3));
254 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
255 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
256 /// nonzero bitboard.
258 #if defined(USE_BSFQ)
260 #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
262 FORCE_INLINE Square first_1(Bitboard b) {
264 _BitScanForward64(&index, b);
265 return (Square) index;
269 FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
271 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
272 return (Square) dummy;
276 FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
277 const Square s = first_1(*b);
282 #else // if !defined(USE_BSFQ)
284 extern Square first_1(Bitboard b);
285 extern Square pop_1st_bit(Bitboard* b);
290 extern void print_bitboard(Bitboard b);
291 extern void init_bitboards();
293 #endif // !defined(BITBOARD_H_INCLUDED)