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 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];
96 extern uint8_t BitCount8Bit[256];
100 //// Inline functions
103 /// Functions for testing whether a given bit is set in a bitboard, and for
104 /// setting and clearing bits.
106 inline Bitboard bit_is_set(Bitboard b, Square s) {
107 return b & SetMaskBB[s];
110 inline void set_bit(Bitboard *b, Square s) {
114 inline void clear_bit(Bitboard *b, Square s) {
115 *b &= ClearMaskBB[s];
119 /// Functions used to update a bitboard after a move. This is faster
120 /// then calling a sequence of clear_bit() + set_bit()
122 inline Bitboard make_move_bb(Square from, Square to) {
123 return SetMaskBB[from] | SetMaskBB[to];
126 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
130 /// rank_bb() and file_bb() gives a bitboard containing all squares on a given
131 /// file or rank. It is also possible to pass a square as input to these
134 inline Bitboard rank_bb(Rank r) {
138 inline Bitboard rank_bb(Square s) {
139 return rank_bb(square_rank(s));
142 inline Bitboard file_bb(File f) {
146 inline Bitboard file_bb(Square s) {
147 return file_bb(square_file(s));
151 /// neighboring_files_bb takes a file or a square as input, and returns a
152 /// bitboard representing all squares on the neighboring files.
154 inline Bitboard neighboring_files_bb(File f) {
155 return NeighboringFilesBB[f];
158 inline Bitboard neighboring_files_bb(Square s) {
159 return neighboring_files_bb(square_file(s));
163 /// this_and_neighboring_files_bb takes a file or a square as input, and
164 /// returns a bitboard representing all squares on the given and neighboring
167 inline Bitboard this_and_neighboring_files_bb(File f) {
168 return ThisAndNeighboringFilesBB[f];
171 inline Bitboard this_and_neighboring_files_bb(Square s) {
172 return this_and_neighboring_files_bb(square_file(s));
176 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
177 /// representing all squares on the given rank from the given color's point of
178 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
179 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
182 inline Bitboard relative_rank_bb(Color c, Rank r) {
183 return RelativeRankBB[c][r];
187 /// in_front_bb() takes a color and a rank or square as input, and returns a
188 /// bitboard representing all the squares on all ranks in front of the rank
189 /// (or square), from the given color's point of view. For instance,
190 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
191 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
193 inline Bitboard in_front_bb(Color c, Rank r) {
194 return InFrontBB[c][r];
197 inline Bitboard in_front_bb(Color c, Square s) {
198 return in_front_bb(c, square_rank(s));
202 /// behind_bb() takes a color and a rank or square as input, and returns a
203 /// bitboard representing all the squares on all ranks behind of the rank
204 /// (or square), from the given color's point of view.
206 inline Bitboard behind_bb(Color c, Rank r) {
207 return InFrontBB[opposite_color(c)][r];
210 inline Bitboard behind_bb(Color c, Square s) {
211 return in_front_bb(opposite_color(c), square_rank(s));
215 /// ray_bb() gives a bitboard representing all squares along the ray in a
216 /// given direction from a given square.
218 inline Bitboard ray_bb(Square s, SignedDirection d) {
223 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
224 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
225 /// bitboard of occupied squares as input, and return a bitboard representing
226 /// all squares attacked by a rook, bishop or queen on the given square.
228 #if defined(IS_64BIT)
230 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
231 Bitboard b = blockers & RMask[s];
232 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
235 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
236 Bitboard b = blockers & BMask[s];
237 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
240 #else // if !defined(IS_64BIT)
242 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
243 Bitboard b = blockers & RMask[s];
244 return RAttacks[RAttackIndex[s] +
245 (unsigned(int(b) * int(RMult[s]) ^
246 int(b >> 32) * int(RMult[s] >> 32))
250 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
251 Bitboard b = blockers & BMask[s];
252 return BAttacks[BAttackIndex[s] +
253 (unsigned(int(b) * int(BMult[s]) ^
254 int(b >> 32) * int(BMult[s] >> 32))
260 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
261 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
265 /// squares_between returns a bitboard representing all squares between
266 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
267 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
268 /// on the same line, file or diagonal, EmptyBoardBB is returned.
270 inline Bitboard squares_between(Square s1, Square s2) {
271 return BetweenBB[s1][s2];
275 /// squares_in_front_of takes a color and a square as input, and returns a
276 /// bitboard representing all squares along the line in front of the square,
277 /// from the point of view of the given color. For instance,
278 /// squares_in_front_of(BLACK, SQ_E4) returns a bitboard with the squares
279 /// e3, e2 and e1 set.
281 inline Bitboard squares_in_front_of(Color c, Square s) {
282 return in_front_bb(c, s) & file_bb(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 in_front_bb(opposite_color(c), s) & file_bb(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.
298 inline Bitboard passed_pawn_mask(Color c, Square s) {
299 return PassedPawnMask[c][s];
303 /// outpost_mask takes a color and a square as input, and returns a bitboard
304 /// mask which can be used to test whether a piece on the square can possibly
305 /// be driven away by an enemy pawn.
307 inline Bitboard outpost_mask(Color c, Square s) {
308 return OutpostMask[c][s];
312 /// isolated_pawn_mask takes a square as input, and returns a bitboard mask
313 /// which can be used to test whether a pawn on the given square is isolated.
315 inline Bitboard isolated_pawn_mask(Square s) {
316 return neighboring_files_bb(s);
320 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
321 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
322 /// nonzero bitboard.
324 #if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
326 inline Square first_1(Bitboard b) {
328 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
329 return (Square)(dummy);
332 inline Square pop_1st_bit(Bitboard* b) {
333 const Square s = first_1(*b);
338 #else // if !defined(USE_BSFQ)
340 extern Square first_1(Bitboard b);
341 extern Square pop_1st_bit(Bitboard* b);
350 extern void print_bitboard(Bitboard b);
351 extern void init_bitboards();
352 extern int bitScanReverse32(uint32_t b);
355 #endif // !defined(BITBOARD_H_INCLUDED)