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 uint64_t RMult[64];
64 extern int RShift[64];
65 extern Bitboard RMask[64];
66 extern Bitboard* RAttacks[64];
68 extern uint64_t BMult[64];
69 extern int BShift[64];
70 extern Bitboard BMask[64];
71 extern Bitboard* BAttacks[64];
73 extern Bitboard BishopPseudoAttacks[64];
74 extern Bitboard RookPseudoAttacks[64];
75 extern Bitboard QueenPseudoAttacks[64];
77 extern uint8_t BitCount8Bit[256];
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 return RAttacks[s][((occ & RMask[s]) * RMult[s]) >> RShift[s]];
178 inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
179 return BAttacks[s][((occ & BMask[s]) * BMult[s]) >> BShift[s]];
182 #else // if !defined(IS_64BIT)
184 inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
185 Bitboard b = occ & RMask[s];
187 [unsigned(int(b) * int(RMult[s]) ^ int(b >> 32) * int(RMult[s] >> 32)) >> RShift[s]];
190 inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
191 Bitboard b = occ & BMask[s];
193 [unsigned(int(b) * int(BMult[s]) ^ int(b >> 32) * int(BMult[s] >> 32)) >> BShift[s]];
198 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
199 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
203 /// squares_between returns a bitboard representing all squares between
204 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
205 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
206 /// on the same line, file or diagonal, EmptyBoardBB is returned.
208 inline Bitboard squares_between(Square s1, Square s2) {
209 return BetweenBB[s1][s2];
213 /// squares_in_front_of takes a color and a square as input, and returns a
214 /// bitboard representing all squares along the line in front of the square,
215 /// from the point of view of the given color. Definition of the table is:
216 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
218 inline Bitboard squares_in_front_of(Color c, Square s) {
219 return SquaresInFrontMask[c][s];
223 /// passed_pawn_mask takes a color and a square as input, and returns a
224 /// bitboard mask which can be used to test if a pawn of the given color on
225 /// the given square is a passed pawn. Definition of the table is:
226 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
228 inline Bitboard passed_pawn_mask(Color c, Square s) {
229 return PassedPawnMask[c][s];
233 /// attack_span_mask takes a color and a square as input, and returns a bitboard
234 /// representing all squares that can be attacked by a pawn of the given color
235 /// when it moves along its file starting from the given square. Definition is:
236 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
238 inline Bitboard attack_span_mask(Color c, Square s) {
239 return AttackSpanMask[c][s];
243 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
244 /// either on a straight or on a diagonal line.
246 inline bool squares_aligned(Square s1, Square s2, Square s3) {
247 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
248 & ( SetMaskBB[s1] | SetMaskBB[s2] | SetMaskBB[s3]);
252 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
253 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
254 /// nonzero bitboard.
256 #if defined(USE_BSFQ)
258 #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
260 FORCE_INLINE Square first_1(Bitboard b) {
262 _BitScanForward64(&index, b);
263 return (Square) index;
267 FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
269 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
270 return (Square) dummy;
274 FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
275 const Square s = first_1(*b);
280 #else // if !defined(USE_BSFQ)
282 extern Square first_1(Bitboard b);
283 extern Square pop_1st_bit(Bitboard* b);
288 extern void print_bitboard(Bitboard b);
289 extern void init_bitboards();
291 #endif // !defined(BITBOARD_H_INCLUDED)