2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2009 Marco Costalba
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
29 #include "direction.h"
36 //// Constants and variables
39 const Bitboard EmptyBoardBB = 0ULL;
41 const Bitboard WhiteSquaresBB = 0x55AA55AA55AA55AAULL;
42 const Bitboard BlackSquaresBB = 0xAA55AA55AA55AA55ULL;
43 const Bitboard SquaresByColorBB[2] = { BlackSquaresBB, WhiteSquaresBB };
45 const Bitboard FileABB = 0x0101010101010101ULL;
46 const Bitboard FileBBB = 0x0202020202020202ULL;
47 const Bitboard FileCBB = 0x0404040404040404ULL;
48 const Bitboard FileDBB = 0x0808080808080808ULL;
49 const Bitboard FileEBB = 0x1010101010101010ULL;
50 const Bitboard FileFBB = 0x2020202020202020ULL;
51 const Bitboard FileGBB = 0x4040404040404040ULL;
52 const Bitboard FileHBB = 0x8080808080808080ULL;
54 const Bitboard FileBB[8] = {
55 FileABB, FileBBB, FileCBB, FileDBB, FileEBB, FileFBB, FileGBB, FileHBB
58 const Bitboard NeighboringFilesBB[8] = {
59 FileBBB, FileABB|FileCBB, FileBBB|FileDBB, FileCBB|FileEBB,
60 FileDBB|FileFBB, FileEBB|FileGBB, FileFBB|FileHBB, FileGBB
63 const Bitboard ThisAndNeighboringFilesBB[8] = {
64 FileABB|FileBBB, FileABB|FileBBB|FileCBB,
65 FileBBB|FileCBB|FileDBB, FileCBB|FileDBB|FileEBB,
66 FileDBB|FileEBB|FileFBB, FileEBB|FileFBB|FileGBB,
67 FileFBB|FileGBB|FileHBB, FileGBB|FileHBB
70 const Bitboard Rank1BB = 0xFFULL;
71 const Bitboard Rank2BB = 0xFF00ULL;
72 const Bitboard Rank3BB = 0xFF0000ULL;
73 const Bitboard Rank4BB = 0xFF000000ULL;
74 const Bitboard Rank5BB = 0xFF00000000ULL;
75 const Bitboard Rank6BB = 0xFF0000000000ULL;
76 const Bitboard Rank7BB = 0xFF000000000000ULL;
77 const Bitboard Rank8BB = 0xFF00000000000000ULL;
79 const Bitboard RankBB[8] = {
80 Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB
83 const Bitboard RelativeRankBB[2][8] = {
84 { Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB },
85 { Rank8BB, Rank7BB, Rank6BB, Rank5BB, Rank4BB, Rank3BB, Rank2BB, Rank1BB }
88 const Bitboard InFrontBB[2][8] = {
89 { Rank2BB | Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
90 Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
91 Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
92 Rank5BB | Rank6BB | Rank7BB | Rank8BB,
93 Rank6BB | Rank7BB | Rank8BB,
101 Rank3BB | Rank2BB | Rank1BB,
102 Rank4BB | Rank3BB | Rank2BB | Rank1BB,
103 Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB,
104 Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB,
105 Rank7BB | Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB
109 extern Bitboard SetMaskBB[65];
110 extern Bitboard ClearMaskBB[65];
112 extern Bitboard StepAttackBB[16][64];
113 extern Bitboard RayBB[64][8];
114 extern Bitboard BetweenBB[64][64];
116 extern Bitboard PassedPawnMask[2][64];
117 extern Bitboard OutpostMask[2][64];
119 extern const uint64_t RMult[64];
120 extern const int RShift[64];
121 extern Bitboard RMask[64];
122 extern int RAttackIndex[64];
123 extern Bitboard RAttacks[0x19000];
125 extern const uint64_t BMult[64];
126 extern const int BShift[64];
127 extern Bitboard BMask[64];
128 extern int BAttackIndex[64];
129 extern Bitboard BAttacks[0x1480];
131 extern Bitboard BishopPseudoAttacks[64];
132 extern Bitboard RookPseudoAttacks[64];
133 extern Bitboard QueenPseudoAttacks[64];
137 //// Inline functions
140 /// Functions for testing whether a given bit is set in a bitboard, and for
141 /// setting and clearing bits.
143 inline Bitboard bit_is_set(Bitboard b, Square s) {
144 return b & SetMaskBB[s];
147 inline void set_bit(Bitboard *b, Square s) {
151 inline void clear_bit(Bitboard *b, Square s) {
152 *b &= ClearMaskBB[s];
156 /// Functions used to update a bitboard after a move. This is faster
157 /// then calling a sequence of clear_bit() + set_bit()
159 inline Bitboard make_move_bb(Square from, Square to) {
160 return SetMaskBB[from] | SetMaskBB[to];
163 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
167 /// rank_bb() and file_bb() gives a bitboard containing all squares on a given
168 /// file or rank. It is also possible to pass a square as input to these
171 inline Bitboard rank_bb(Rank r) {
175 inline Bitboard rank_bb(Square s) {
176 return rank_bb(square_rank(s));
179 inline Bitboard file_bb(File f) {
183 inline Bitboard file_bb(Square s) {
184 return file_bb(square_file(s));
188 /// neighboring_files_bb takes a file or a square as input, and returns a
189 /// bitboard representing all squares on the neighboring files.
191 inline Bitboard neighboring_files_bb(File f) {
192 return NeighboringFilesBB[f];
195 inline Bitboard neighboring_files_bb(Square s) {
196 return neighboring_files_bb(square_file(s));
200 /// this_and_neighboring_files_bb takes a file or a square as input, and
201 /// returns a bitboard representing all squares on the given and neighboring
204 inline Bitboard this_and_neighboring_files_bb(File f) {
205 return ThisAndNeighboringFilesBB[f];
208 inline Bitboard this_and_neighboring_files_bb(Square s) {
209 return this_and_neighboring_files_bb(square_file(s));
213 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
214 /// representing all squares on the given rank from the given color's point of
215 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
216 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
219 inline Bitboard relative_rank_bb(Color c, Rank r) {
220 return RelativeRankBB[c][r];
224 /// in_front_bb() takes a color and a rank or square as input, and returns a
225 /// bitboard representing all the squares on all ranks in front of the rank
226 /// (or square), from the given color's point of view. For instance,
227 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
228 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
230 inline Bitboard in_front_bb(Color c, Rank r) {
231 return InFrontBB[c][r];
234 inline Bitboard in_front_bb(Color c, Square s) {
235 return in_front_bb(c, square_rank(s));
239 /// behind_bb() takes a color and a rank or square as input, and returns a
240 /// bitboard representing all the squares on all ranks behind of the rank
241 /// (or square), from the given color's point of view.
243 inline Bitboard behind_bb(Color c, Rank r) {
244 return InFrontBB[opposite_color(c)][r];
247 inline Bitboard behind_bb(Color c, Square s) {
248 return in_front_bb(opposite_color(c), square_rank(s));
252 /// ray_bb() gives a bitboard representing all squares along the ray in a
253 /// given direction from a given square.
255 inline Bitboard ray_bb(Square s, SignedDirection d) {
260 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
261 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
262 /// bitboard of occupied squares as input, and return a bitboard representing
263 /// all squares attacked by a rook, bishop or queen on the given square.
265 #if defined(IS_64BIT)
267 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
268 Bitboard b = blockers & RMask[s];
269 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
272 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
273 Bitboard b = blockers & BMask[s];
274 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
277 #else // if !defined(IS_64BIT)
279 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
280 Bitboard b = blockers & RMask[s];
281 return RAttacks[RAttackIndex[s] +
282 (unsigned(int(b) * int(RMult[s]) ^
283 int(b >> 32) * int(RMult[s] >> 32))
287 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
288 Bitboard b = blockers & BMask[s];
289 return BAttacks[BAttackIndex[s] +
290 (unsigned(int(b) * int(BMult[s]) ^
291 int(b >> 32) * int(BMult[s] >> 32))
297 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
298 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
302 /// squares_between returns a bitboard representing all squares between
303 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
304 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
305 /// on the same line, file or diagonal, EmptyBoardBB is returned.
307 inline Bitboard squares_between(Square s1, Square s2) {
308 return BetweenBB[s1][s2];
312 /// squares_in_front_of takes a color and a square as input, and returns a
313 /// bitboard representing all squares along the line in front of the square,
314 /// from the point of view of the given color. For instance,
315 /// squares_in_front_of(BLACK, SQ_E4) returns a bitboard with the squares
316 /// e3, e2 and e1 set.
318 inline Bitboard squares_in_front_of(Color c, Square s) {
319 return in_front_bb(c, s) & file_bb(s);
323 /// squares_behind is similar to squares_in_front, but returns the squares
324 /// behind the square instead of in front of the square.
326 inline Bitboard squares_behind(Color c, Square s) {
327 return in_front_bb(opposite_color(c), s) & file_bb(s);
331 /// passed_pawn_mask takes a color and a square as input, and returns a
332 /// bitboard mask which can be used to test if a pawn of the given color on
333 /// the given square is a passed pawn.
335 inline Bitboard passed_pawn_mask(Color c, Square s) {
336 return PassedPawnMask[c][s];
340 /// outpost_mask takes a color and a square as input, and returns a bitboard
341 /// mask which can be used to test whether a piece on the square can possibly
342 /// be driven away by an enemy pawn.
344 inline Bitboard outpost_mask(Color c, Square s) {
345 return OutpostMask[c][s];
349 /// isolated_pawn_mask takes a square as input, and returns a bitboard mask
350 /// which can be used to test whether a pawn on the given square is isolated.
352 inline Bitboard isolated_pawn_mask(Square s) {
353 return neighboring_files_bb(s);
357 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
358 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
359 /// nonzero bitboard.
361 #if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
363 inline Square __attribute__((always_inline)) first_1(Bitboard b) {
365 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
366 return (Square)(dummy);
369 inline Square __attribute__((always_inline)) pop_1st_bit(Bitboard* b) {
370 const Square s = first_1(*b);
375 #else // if !defined(USE_BSFQ)
377 extern Square first_1(Bitboard b);
378 extern Square pop_1st_bit(Bitboard* b);
387 extern void print_bitboard(Bitboard b);
388 extern void init_bitboards();
391 #endif // !defined(BITBOARD_H_INCLUDED)