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/>.
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 FileABB = 0x0101010101010101ULL;
42 const Bitboard FileBBB = 0x0202020202020202ULL;
43 const Bitboard FileCBB = 0x0404040404040404ULL;
44 const Bitboard FileDBB = 0x0808080808080808ULL;
45 const Bitboard FileEBB = 0x1010101010101010ULL;
46 const Bitboard FileFBB = 0x2020202020202020ULL;
47 const Bitboard FileGBB = 0x4040404040404040ULL;
48 const Bitboard FileHBB = 0x8080808080808080ULL;
50 const Bitboard Rank1BB = 0xFFULL;
51 const Bitboard Rank2BB = 0xFF00ULL;
52 const Bitboard Rank3BB = 0xFF0000ULL;
53 const Bitboard Rank4BB = 0xFF000000ULL;
54 const Bitboard Rank5BB = 0xFF00000000ULL;
55 const Bitboard Rank6BB = 0xFF0000000000ULL;
56 const Bitboard Rank7BB = 0xFF000000000000ULL;
57 const Bitboard Rank8BB = 0xFF00000000000000ULL;
59 extern const Bitboard SquaresByColorBB[2];
60 extern const Bitboard FileBB[8];
61 extern const Bitboard NeighboringFilesBB[8];
62 extern const Bitboard ThisAndNeighboringFilesBB[8];
63 extern const Bitboard RankBB[8];
64 extern const Bitboard RelativeRankBB[2][8];
65 extern const Bitboard InFrontBB[2][8];
67 extern Bitboard SetMaskBB[65];
68 extern Bitboard ClearMaskBB[65];
70 extern Bitboard StepAttackBB[16][64];
71 extern Bitboard RayBB[64][8];
72 extern Bitboard BetweenBB[64][64];
74 extern Bitboard SquaresInFrontMask[2][64];
75 extern Bitboard PassedPawnMask[2][64];
76 extern Bitboard AttackSpanMask[2][64];
78 extern const uint64_t RMult[64];
79 extern const int RShift[64];
80 extern Bitboard RMask[64];
81 extern int RAttackIndex[64];
82 extern Bitboard RAttacks[0x19000];
84 extern const uint64_t BMult[64];
85 extern const int BShift[64];
86 extern Bitboard BMask[64];
87 extern int BAttackIndex[64];
88 extern Bitboard BAttacks[0x1480];
90 extern Bitboard BishopPseudoAttacks[64];
91 extern Bitboard RookPseudoAttacks[64];
92 extern Bitboard QueenPseudoAttacks[64];
94 extern uint8_t BitCount8Bit[256];
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() take a file or a square as input, and return
129 /// a bitboard representing all squares on the given file or rank.
131 inline Bitboard rank_bb(Rank r) {
135 inline Bitboard rank_bb(Square s) {
136 return rank_bb(square_rank(s));
139 inline Bitboard file_bb(File f) {
143 inline Bitboard file_bb(Square s) {
144 return file_bb(square_file(s));
148 /// neighboring_files_bb takes a file or a square as input, and returns a
149 /// bitboard representing all squares on the neighboring files.
151 inline Bitboard neighboring_files_bb(File f) {
152 return NeighboringFilesBB[f];
155 inline Bitboard neighboring_files_bb(Square s) {
156 return NeighboringFilesBB[square_file(s)];
160 /// this_and_neighboring_files_bb takes a file or a square as input, and
161 /// returns a bitboard representing all squares on the given and neighboring
164 inline Bitboard this_and_neighboring_files_bb(File f) {
165 return ThisAndNeighboringFilesBB[f];
168 inline Bitboard this_and_neighboring_files_bb(Square s) {
169 return ThisAndNeighboringFilesBB[square_file(s)];
173 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
174 /// representing all squares on the given rank from the given color's point of
175 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
176 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
179 inline Bitboard relative_rank_bb(Color c, Rank r) {
180 return RelativeRankBB[c][r];
184 /// in_front_bb() takes a color and a rank or square as input, and returns a
185 /// bitboard representing all the squares on all ranks in front of the rank
186 /// (or square), from the given color's point of view. For instance,
187 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
188 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
190 inline Bitboard in_front_bb(Color c, Rank r) {
191 return InFrontBB[c][r];
194 inline Bitboard in_front_bb(Color c, Square s) {
195 return InFrontBB[c][square_rank(s)];
199 /// behind_bb() takes a color and a rank or square as input, and returns a
200 /// bitboard representing all the squares on all ranks behind of the rank
201 /// (or square), from the given color's point of view.
203 inline Bitboard behind_bb(Color c, Rank r) {
204 return InFrontBB[opposite_color(c)][r];
207 inline Bitboard behind_bb(Color c, Square s) {
208 return InFrontBB[opposite_color(c)][square_rank(s)];
212 /// ray_bb() gives a bitboard representing all squares along the ray in a
213 /// given direction from a given square.
215 inline Bitboard ray_bb(Square s, SignedDirection d) {
220 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
221 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
222 /// bitboard of occupied squares as input, and return a bitboard representing
223 /// all squares attacked by a rook, bishop or queen on the given square.
225 #if defined(IS_64BIT)
227 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
228 Bitboard b = blockers & RMask[s];
229 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
232 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
233 Bitboard b = blockers & BMask[s];
234 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
237 #else // if !defined(IS_64BIT)
239 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
240 Bitboard b = blockers & RMask[s];
241 return RAttacks[RAttackIndex[s] +
242 (unsigned(int(b) * int(RMult[s]) ^
243 int(b >> 32) * int(RMult[s] >> 32))
247 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
248 Bitboard b = blockers & BMask[s];
249 return BAttacks[BAttackIndex[s] +
250 (unsigned(int(b) * int(BMult[s]) ^
251 int(b >> 32) * int(BMult[s] >> 32))
257 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
258 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
262 /// squares_between returns a bitboard representing all squares between
263 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
264 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
265 /// on the same line, file or diagonal, EmptyBoardBB is returned.
267 inline Bitboard squares_between(Square s1, Square s2) {
268 return BetweenBB[s1][s2];
272 /// squares_in_front_of takes a color and a square as input, and returns a
273 /// bitboard representing all squares along the line in front of the square,
274 /// from the point of view of the given color. Definition of the table is:
275 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
277 inline Bitboard squares_in_front_of(Color c, Square s) {
278 return SquaresInFrontMask[c][s];
282 /// squares_behind is similar to squares_in_front, but returns the squares
283 /// behind the square instead of in front of the square.
285 inline Bitboard squares_behind(Color c, Square s) {
286 return SquaresInFrontMask[opposite_color(c)][s];
290 /// passed_pawn_mask takes a color and a square as input, and returns a
291 /// bitboard mask which can be used to test if a pawn of the given color on
292 /// the given square is a passed pawn. Definition of the table is:
293 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
295 inline Bitboard passed_pawn_mask(Color c, Square s) {
296 return PassedPawnMask[c][s];
300 /// attack_span_mask takes a color and a square as input, and returns a bitboard
301 /// representing all squares that can be attacked by a pawn of the given color
302 /// when it moves along its file starting from the given square. Definition is:
303 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
305 inline Bitboard attack_span_mask(Color c, Square s) {
306 return AttackSpanMask[c][s];
310 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
311 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
312 /// nonzero bitboard.
314 #if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
316 inline Square first_1(Bitboard b) {
318 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
319 return (Square)(dummy);
322 inline Square pop_1st_bit(Bitboard* b) {
323 const Square s = first_1(*b);
328 #else // if !defined(USE_BSFQ)
330 extern Square first_1(Bitboard b);
331 extern Square pop_1st_bit(Bitboard* b);
340 extern void print_bitboard(Bitboard b);
341 extern void init_bitboards();
344 #endif // !defined(BITBOARD_H_INCLUDED)