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;
44 const Bitboard FileABB = 0x0101010101010101ULL;
45 const Bitboard FileBBB = 0x0202020202020202ULL;
46 const Bitboard FileCBB = 0x0404040404040404ULL;
47 const Bitboard FileDBB = 0x0808080808080808ULL;
48 const Bitboard FileEBB = 0x1010101010101010ULL;
49 const Bitboard FileFBB = 0x2020202020202020ULL;
50 const Bitboard FileGBB = 0x4040404040404040ULL;
51 const Bitboard FileHBB = 0x8080808080808080ULL;
53 const Bitboard Rank1BB = 0xFFULL;
54 const Bitboard Rank2BB = 0xFF00ULL;
55 const Bitboard Rank3BB = 0xFF0000ULL;
56 const Bitboard Rank4BB = 0xFF000000ULL;
57 const Bitboard Rank5BB = 0xFF00000000ULL;
58 const Bitboard Rank6BB = 0xFF0000000000ULL;
59 const Bitboard Rank7BB = 0xFF000000000000ULL;
60 const Bitboard Rank8BB = 0xFF00000000000000ULL;
62 extern const Bitboard SquaresByColorBB[2];
63 extern const Bitboard FileBB[8];
64 extern const Bitboard NeighboringFilesBB[8];
65 extern const Bitboard ThisAndNeighboringFilesBB[8];
66 extern const Bitboard RankBB[8];
67 extern const Bitboard RelativeRankBB[2][8];
68 extern const Bitboard InFrontBB[2][8];
70 extern Bitboard SetMaskBB[65];
71 extern Bitboard ClearMaskBB[65];
73 extern Bitboard StepAttackBB[16][64];
74 extern Bitboard RayBB[64][8];
75 extern Bitboard BetweenBB[64][64];
77 extern Bitboard PassedPawnMask[2][64];
78 extern Bitboard OutpostMask[2][64];
80 extern const uint64_t RMult[64];
81 extern const int RShift[64];
82 extern Bitboard RMask[64];
83 extern int RAttackIndex[64];
84 extern Bitboard RAttacks[0x19000];
86 extern const uint64_t BMult[64];
87 extern const int BShift[64];
88 extern Bitboard BMask[64];
89 extern int BAttackIndex[64];
90 extern Bitboard BAttacks[0x1480];
92 extern Bitboard BishopPseudoAttacks[64];
93 extern Bitboard RookPseudoAttacks[64];
94 extern Bitboard QueenPseudoAttacks[64];
101 /// Functions for testing whether a given bit is set in a bitboard, and for
102 /// setting and clearing bits.
104 inline Bitboard bit_is_set(Bitboard b, Square s) {
105 return b & SetMaskBB[s];
108 inline void set_bit(Bitboard *b, Square s) {
112 inline void clear_bit(Bitboard *b, Square s) {
113 *b &= ClearMaskBB[s];
117 /// Functions used to update a bitboard after a move. This is faster
118 /// then calling a sequence of clear_bit() + set_bit()
120 inline Bitboard make_move_bb(Square from, Square to) {
121 return SetMaskBB[from] | SetMaskBB[to];
124 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
128 /// rank_bb() and file_bb() gives a bitboard containing all squares on a given
129 /// file or rank. It is also possible to pass a square as input to these
132 inline Bitboard rank_bb(Rank r) {
136 inline Bitboard rank_bb(Square s) {
137 return rank_bb(square_rank(s));
140 inline Bitboard file_bb(File f) {
144 inline Bitboard file_bb(Square s) {
145 return file_bb(square_file(s));
149 /// neighboring_files_bb takes a file or a square as input, and returns a
150 /// bitboard representing all squares on the neighboring files.
152 inline Bitboard neighboring_files_bb(File f) {
153 return NeighboringFilesBB[f];
156 inline Bitboard neighboring_files_bb(Square s) {
157 return neighboring_files_bb(square_file(s));
161 /// this_and_neighboring_files_bb takes a file or a square as input, and
162 /// returns a bitboard representing all squares on the given and neighboring
165 inline Bitboard this_and_neighboring_files_bb(File f) {
166 return ThisAndNeighboringFilesBB[f];
169 inline Bitboard this_and_neighboring_files_bb(Square s) {
170 return this_and_neighboring_files_bb(square_file(s));
174 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
175 /// representing all squares on the given rank from the given color's point of
176 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
177 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
180 inline Bitboard relative_rank_bb(Color c, Rank r) {
181 return RelativeRankBB[c][r];
185 /// in_front_bb() takes a color and a rank or square as input, and returns a
186 /// bitboard representing all the squares on all ranks in front of the rank
187 /// (or square), from the given color's point of view. For instance,
188 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
189 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
191 inline Bitboard in_front_bb(Color c, Rank r) {
192 return InFrontBB[c][r];
195 inline Bitboard in_front_bb(Color c, Square s) {
196 return in_front_bb(c, square_rank(s));
200 /// behind_bb() takes a color and a rank or square as input, and returns a
201 /// bitboard representing all the squares on all ranks behind of the rank
202 /// (or square), from the given color's point of view.
204 inline Bitboard behind_bb(Color c, Rank r) {
205 return InFrontBB[opposite_color(c)][r];
208 inline Bitboard behind_bb(Color c, Square s) {
209 return in_front_bb(opposite_color(c), square_rank(s));
213 /// ray_bb() gives a bitboard representing all squares along the ray in a
214 /// given direction from a given square.
216 inline Bitboard ray_bb(Square s, SignedDirection d) {
221 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
222 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
223 /// bitboard of occupied squares as input, and return a bitboard representing
224 /// all squares attacked by a rook, bishop or queen on the given square.
226 #if defined(IS_64BIT)
228 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
229 Bitboard b = blockers & RMask[s];
230 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
233 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
234 Bitboard b = blockers & BMask[s];
235 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
238 #else // if !defined(IS_64BIT)
240 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
241 Bitboard b = blockers & RMask[s];
242 return RAttacks[RAttackIndex[s] +
243 (unsigned(int(b) * int(RMult[s]) ^
244 int(b >> 32) * int(RMult[s] >> 32))
248 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
249 Bitboard b = blockers & BMask[s];
250 return BAttacks[BAttackIndex[s] +
251 (unsigned(int(b) * int(BMult[s]) ^
252 int(b >> 32) * int(BMult[s] >> 32))
258 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
259 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
263 /// squares_between returns a bitboard representing all squares between
264 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
265 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
266 /// on the same line, file or diagonal, EmptyBoardBB is returned.
268 inline Bitboard squares_between(Square s1, Square s2) {
269 return BetweenBB[s1][s2];
273 /// squares_in_front_of takes a color and a square as input, and returns a
274 /// bitboard representing all squares along the line in front of the square,
275 /// from the point of view of the given color. For instance,
276 /// squares_in_front_of(BLACK, SQ_E4) returns a bitboard with the squares
277 /// e3, e2 and e1 set.
279 inline Bitboard squares_in_front_of(Color c, Square s) {
280 return in_front_bb(c, s) & file_bb(s);
284 /// squares_behind is similar to squares_in_front, but returns the squares
285 /// behind the square instead of in front of the square.
287 inline Bitboard squares_behind(Color c, Square s) {
288 return in_front_bb(opposite_color(c), s) & file_bb(s);
292 /// passed_pawn_mask takes a color and a square as input, and returns a
293 /// bitboard mask which can be used to test if a pawn of the given color on
294 /// the given square is a passed pawn.
296 inline Bitboard passed_pawn_mask(Color c, Square s) {
297 return PassedPawnMask[c][s];
301 /// outpost_mask takes a color and a square as input, and returns a bitboard
302 /// mask which can be used to test whether a piece on the square can possibly
303 /// be driven away by an enemy pawn.
305 inline Bitboard outpost_mask(Color c, Square s) {
306 return OutpostMask[c][s];
310 /// isolated_pawn_mask takes a square as input, and returns a bitboard mask
311 /// which can be used to test whether a pawn on the given square is isolated.
313 inline Bitboard isolated_pawn_mask(Square s) {
314 return neighboring_files_bb(s);
318 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
319 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
320 /// nonzero bitboard.
322 #if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
324 inline Square __attribute__((always_inline)) first_1(Bitboard b) {
326 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
327 return (Square)(dummy);
330 inline Square __attribute__((always_inline)) pop_1st_bit(Bitboard* b) {
331 const Square s = first_1(*b);
336 #else // if !defined(USE_BSFQ)
338 extern Square first_1(Bitboard b);
339 extern Square pop_1st_bit(Bitboard* b);
348 extern void print_bitboard(Bitboard b);
349 extern void init_bitboards();
352 #endif // !defined(BITBOARD_H_INCLUDED)