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 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 SquaresInFrontMask[2][64];
78 extern Bitboard PassedPawnMask[2][64];
79 extern Bitboard OutpostMask[2][64];
81 extern const uint64_t RMult[64];
82 extern const int RShift[64];
83 extern Bitboard RMask[64];
84 extern int RAttackIndex[64];
85 extern Bitboard RAttacks[0x19000];
87 extern const uint64_t BMult[64];
88 extern const int BShift[64];
89 extern Bitboard BMask[64];
90 extern int BAttackIndex[64];
91 extern Bitboard BAttacks[0x1480];
93 extern Bitboard BishopPseudoAttacks[64];
94 extern Bitboard RookPseudoAttacks[64];
95 extern Bitboard QueenPseudoAttacks[64];
97 extern uint8_t BitCount8Bit[256];
101 //// Inline functions
104 /// Functions for testing whether a given bit is set in a bitboard, and for
105 /// setting and clearing bits.
107 inline Bitboard bit_is_set(Bitboard b, Square s) {
108 return b & SetMaskBB[s];
111 inline void set_bit(Bitboard *b, Square s) {
115 inline void clear_bit(Bitboard *b, Square s) {
116 *b &= ClearMaskBB[s];
120 /// Functions used to update a bitboard after a move. This is faster
121 /// then calling a sequence of clear_bit() + set_bit()
123 inline Bitboard make_move_bb(Square from, Square to) {
124 return SetMaskBB[from] | SetMaskBB[to];
127 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
131 /// rank_bb() and file_bb() gives a bitboard containing all squares on a given
132 /// file or rank. It is also possible to pass a square as input to these
135 inline Bitboard rank_bb(Rank r) {
139 inline Bitboard rank_bb(Square s) {
140 return rank_bb(square_rank(s));
143 inline Bitboard file_bb(File f) {
147 inline Bitboard file_bb(Square s) {
148 return file_bb(square_file(s));
152 /// neighboring_files_bb takes a file or a square as input, and returns a
153 /// bitboard representing all squares on the neighboring files.
155 inline Bitboard neighboring_files_bb(File f) {
156 return NeighboringFilesBB[f];
159 inline Bitboard neighboring_files_bb(Square s) {
160 return NeighboringFilesBB[square_file(s)];
164 /// this_and_neighboring_files_bb takes a file or a square as input, and
165 /// returns a bitboard representing all squares on the given and neighboring
168 inline Bitboard this_and_neighboring_files_bb(File f) {
169 return ThisAndNeighboringFilesBB[f];
172 inline Bitboard this_and_neighboring_files_bb(Square s) {
173 return ThisAndNeighboringFilesBB[square_file(s)];
177 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
178 /// representing all squares on the given rank from the given color's point of
179 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
180 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
183 inline Bitboard relative_rank_bb(Color c, Rank r) {
184 return RelativeRankBB[c][r];
188 /// in_front_bb() takes a color and a rank or square as input, and returns a
189 /// bitboard representing all the squares on all ranks in front of the rank
190 /// (or square), from the given color's point of view. For instance,
191 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
192 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
194 inline Bitboard in_front_bb(Color c, Rank r) {
195 return InFrontBB[c][r];
198 inline Bitboard in_front_bb(Color c, Square s) {
199 return InFrontBB[c][square_rank(s)];
203 /// behind_bb() takes a color and a rank or square as input, and returns a
204 /// bitboard representing all the squares on all ranks behind of the rank
205 /// (or square), from the given color's point of view.
207 inline Bitboard behind_bb(Color c, Rank r) {
208 return InFrontBB[opposite_color(c)][r];
211 inline Bitboard behind_bb(Color c, Square s) {
212 return InFrontBB[opposite_color(c)][square_rank(s)];
216 /// ray_bb() gives a bitboard representing all squares along the ray in a
217 /// given direction from a given square.
219 inline Bitboard ray_bb(Square s, SignedDirection d) {
224 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
225 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
226 /// bitboard of occupied squares as input, and return a bitboard representing
227 /// all squares attacked by a rook, bishop or queen on the given square.
229 #if defined(IS_64BIT)
231 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
232 Bitboard b = blockers & RMask[s];
233 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
236 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
237 Bitboard b = blockers & BMask[s];
238 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
241 #else // if !defined(IS_64BIT)
243 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
244 Bitboard b = blockers & RMask[s];
245 return RAttacks[RAttackIndex[s] +
246 (unsigned(int(b) * int(RMult[s]) ^
247 int(b >> 32) * int(RMult[s] >> 32))
251 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
252 Bitboard b = blockers & BMask[s];
253 return BAttacks[BAttackIndex[s] +
254 (unsigned(int(b) * int(BMult[s]) ^
255 int(b >> 32) * int(BMult[s] >> 32))
261 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
262 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
266 /// squares_between returns a bitboard representing all squares between
267 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
268 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
269 /// on the same line, file or diagonal, EmptyBoardBB is returned.
271 inline Bitboard squares_between(Square s1, Square s2) {
272 return BetweenBB[s1][s2];
276 /// squares_in_front_of takes a color and a square as input, and returns a
277 /// bitboard representing all squares along the line in front of the square,
278 /// from the point of view of the given color. Definition of the table is:
279 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
281 inline Bitboard squares_in_front_of(Color c, Square s) {
282 return SquaresInFrontMask[c][s];
286 /// squares_behind is similar to squares_in_front, but returns the squares
287 /// behind the square instead of in front of the square.
289 inline Bitboard squares_behind(Color c, Square s) {
290 return SquaresInFrontMask[opposite_color(c)][s];
294 /// passed_pawn_mask takes a color and a square as input, and returns a
295 /// bitboard mask which can be used to test if a pawn of the given color on
296 /// the given square is a passed pawn. Definition of the table is:
297 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
299 inline Bitboard passed_pawn_mask(Color c, Square s) {
300 return PassedPawnMask[c][s];
304 /// outpost_mask takes a color and a square as input, and returns a bitboard
305 /// mask which can be used to test whether a piece on the square can possibly
306 /// be driven away by an enemy pawn. Definition of the table is:
307 /// OutpostMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
309 inline Bitboard outpost_mask(Color c, Square s) {
310 return OutpostMask[c][s];
314 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
315 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
316 /// nonzero bitboard.
318 #if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
320 inline Square first_1(Bitboard b) {
322 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
323 return (Square)(dummy);
326 inline Square pop_1st_bit(Bitboard* b) {
327 const Square s = first_1(*b);
332 #else // if !defined(USE_BSFQ)
334 extern Square first_1(Bitboard b);
335 extern Square pop_1st_bit(Bitboard* b);
344 extern void print_bitboard(Bitboard b);
345 extern void init_bitboards();
346 extern int bitScanReverse32(uint32_t b);
349 #endif // !defined(BITBOARD_H_INCLUDED)