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
30 // Comment following define if you prefer manually adjust
31 // platform macros defined below
32 #define AUTO_CONFIGURATION
34 // Quiet a warning on Intel compiler
35 #if !defined(__SIZEOF_INT__ )
36 #define __SIZEOF_INT__ 0
39 // Check for 64 bits for different compilers: Intel, MSVC and gcc
40 #if defined(__x86_64) || defined(_WIN64) || (__SIZEOF_INT__ > 4)
44 #if !defined(AUTO_CONFIGURATION) || defined(IS_64BIT)
46 //#define USE_COMPACT_ROOK_ATTACKS
47 //#define USE_32BIT_ATTACKS
48 #define USE_FOLDED_BITSCAN
50 #define BITCOUNT_SWAR_64
51 //#define BITCOUNT_SWAR_32
52 //#define BITCOUNT_LOOP
56 #define USE_32BIT_ATTACKS
57 #define USE_FOLDED_BITSCAN
58 #define BITCOUNT_SWAR_32
66 #include "direction.h"
76 typedef uint64_t Bitboard;
80 //// Constants and variables
83 const Bitboard EmptyBoardBB = 0ULL;
85 const Bitboard WhiteSquaresBB = 0x55AA55AA55AA55AAULL;
86 const Bitboard BlackSquaresBB = 0xAA55AA55AA55AA55ULL;
87 const Bitboard SquaresByColorBB[2] = { BlackSquaresBB, WhiteSquaresBB };
89 const Bitboard FileABB = 0x0101010101010101ULL;
90 const Bitboard FileBBB = 0x0202020202020202ULL;
91 const Bitboard FileCBB = 0x0404040404040404ULL;
92 const Bitboard FileDBB = 0x0808080808080808ULL;
93 const Bitboard FileEBB = 0x1010101010101010ULL;
94 const Bitboard FileFBB = 0x2020202020202020ULL;
95 const Bitboard FileGBB = 0x4040404040404040ULL;
96 const Bitboard FileHBB = 0x8080808080808080ULL;
98 const Bitboard FileBB[8] = {
99 FileABB, FileBBB, FileCBB, FileDBB, FileEBB, FileFBB, FileGBB, FileHBB
102 const Bitboard NeighboringFilesBB[8] = {
103 FileBBB, FileABB|FileCBB, FileBBB|FileDBB, FileCBB|FileEBB,
104 FileDBB|FileFBB, FileEBB|FileGBB, FileFBB|FileHBB, FileGBB
107 const Bitboard ThisAndNeighboringFilesBB[8] = {
108 FileABB|FileBBB, FileABB|FileBBB|FileCBB,
109 FileBBB|FileCBB|FileDBB, FileCBB|FileDBB|FileEBB,
110 FileDBB|FileEBB|FileFBB, FileEBB|FileFBB|FileGBB,
111 FileFBB|FileGBB|FileHBB, FileGBB|FileHBB
114 const Bitboard Rank1BB = 0xFFULL;
115 const Bitboard Rank2BB = 0xFF00ULL;
116 const Bitboard Rank3BB = 0xFF0000ULL;
117 const Bitboard Rank4BB = 0xFF000000ULL;
118 const Bitboard Rank5BB = 0xFF00000000ULL;
119 const Bitboard Rank6BB = 0xFF0000000000ULL;
120 const Bitboard Rank7BB = 0xFF000000000000ULL;
121 const Bitboard Rank8BB = 0xFF00000000000000ULL;
123 const Bitboard RankBB[8] = {
124 Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB
127 const Bitboard RelativeRankBB[2][8] = {
128 { Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB },
129 { Rank8BB, Rank7BB, Rank6BB, Rank5BB, Rank4BB, Rank3BB, Rank2BB, Rank1BB }
132 const Bitboard InFrontBB[2][8] = {
133 { Rank2BB | Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
134 Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
135 Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
136 Rank5BB | Rank6BB | Rank7BB | Rank8BB,
137 Rank6BB | Rank7BB | Rank8BB,
145 Rank3BB | Rank2BB | Rank1BB,
146 Rank4BB | Rank3BB | Rank2BB | Rank1BB,
147 Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB,
148 Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB,
149 Rank7BB | Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB
153 extern Bitboard SetMaskBB[65];
154 extern Bitboard ClearMaskBB[65];
156 extern Bitboard StepAttackBB[16][64];
157 extern Bitboard RayBB[64][8];
158 extern Bitboard BetweenBB[64][64];
160 extern Bitboard PassedPawnMask[2][64];
161 extern Bitboard OutpostMask[2][64];
163 #if defined(USE_COMPACT_ROOK_ATTACKS)
165 extern Bitboard RankAttacks[8][64], FileAttacks[8][64];
169 extern const uint64_t RMult[64];
170 extern const int RShift[64];
171 extern Bitboard RMask[64];
172 extern int RAttackIndex[64];
173 extern Bitboard RAttacks[0x19000];
175 #endif // defined(USE_COMPACT_ROOK_ATTACKS)
177 extern const uint64_t BMult[64];
178 extern const int BShift[64];
179 extern Bitboard BMask[64];
180 extern int BAttackIndex[64];
181 extern Bitboard BAttacks[0x1480];
183 extern Bitboard BishopPseudoAttacks[64];
184 extern Bitboard RookPseudoAttacks[64];
185 extern Bitboard QueenPseudoAttacks[64];
189 //// Inline functions
192 /// Functions for testing whether a given bit is set in a bitboard, and for
193 /// setting and clearing bits.
195 inline Bitboard bit_is_set(Bitboard b, Square s) {
196 return b & SetMaskBB[s];
199 inline void set_bit(Bitboard *b, Square s) {
203 inline void clear_bit(Bitboard *b, Square s) {
204 *b &= ClearMaskBB[s];
208 /// Functions used to update a bitboard after a move. This is faster
209 /// then calling a sequence of clear_bit() + set_bit()
211 inline Bitboard make_move_bb(Square from, Square to) {
212 return SetMaskBB[from] | SetMaskBB[to];
215 inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
219 /// rank_bb() and file_bb() gives a bitboard containing all squares on a given
220 /// file or rank. It is also possible to pass a square as input to these
223 inline Bitboard rank_bb(Rank r) {
227 inline Bitboard rank_bb(Square s) {
228 return rank_bb(square_rank(s));
231 inline Bitboard file_bb(File f) {
235 inline Bitboard file_bb(Square s) {
236 return file_bb(square_file(s));
240 /// neighboring_files_bb takes a file or a square as input, and returns a
241 /// bitboard representing all squares on the neighboring files.
243 inline Bitboard neighboring_files_bb(File f) {
244 return NeighboringFilesBB[f];
247 inline Bitboard neighboring_files_bb(Square s) {
248 return neighboring_files_bb(square_file(s));
252 /// this_and_neighboring_files_bb takes a file or a square as input, and
253 /// returns a bitboard representing all squares on the given and neighboring
256 inline Bitboard this_and_neighboring_files_bb(File f) {
257 return ThisAndNeighboringFilesBB[f];
260 inline Bitboard this_and_neighboring_files_bb(Square s) {
261 return this_and_neighboring_files_bb(square_file(s));
265 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
266 /// representing all squares on the given rank from the given color's point of
267 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
268 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
271 inline Bitboard relative_rank_bb(Color c, Rank r) {
272 return RelativeRankBB[c][r];
276 /// in_front_bb() takes a color and a rank or square as input, and returns a
277 /// bitboard representing all the squares on all ranks in front of the rank
278 /// (or square), from the given color's point of view. For instance,
279 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
280 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
282 inline Bitboard in_front_bb(Color c, Rank r) {
283 return InFrontBB[c][r];
286 inline Bitboard in_front_bb(Color c, Square s) {
287 return in_front_bb(c, square_rank(s));
291 /// behind_bb() takes a color and a rank or square as input, and returns a
292 /// bitboard representing all the squares on all ranks behind of the rank
293 /// (or square), from the given color's point of view.
295 inline Bitboard behind_bb(Color c, Rank r) {
296 return InFrontBB[opposite_color(c)][r];
299 inline Bitboard behind_bb(Color c, Square s) {
300 return in_front_bb(opposite_color(c), square_rank(s));
304 /// ray_bb() gives a bitboard representing all squares along the ray in a
305 /// given direction from a given square.
307 inline Bitboard ray_bb(Square s, SignedDirection d) {
312 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
313 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
314 /// bitboard of occupied squares as input, and return a bitboard representing
315 /// all squares attacked by a rook, bishop or queen on the given square.
317 #if defined(USE_COMPACT_ROOK_ATTACKS)
319 inline Bitboard file_attacks_bb(Square s, Bitboard blockers) {
320 Bitboard b = (blockers >> square_file(s)) & 0x01010101010100ULL;
322 FileAttacks[square_rank(s)][(b*0xd6e8802041d0c441ULL)>>58] & file_bb(s);
325 inline Bitboard rank_attacks_bb(Square s, Bitboard blockers) {
326 Bitboard b = (blockers >> ((s & 56) + 1)) & 63;
327 return RankAttacks[square_file(s)][b] & rank_bb(s);
330 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
331 return file_attacks_bb(s, blockers) | rank_attacks_bb(s, blockers);
334 #elif defined(USE_32BIT_ATTACKS)
336 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
337 Bitboard b = blockers & RMask[s];
338 return RAttacks[RAttackIndex[s] +
339 (unsigned(int(b) * int(RMult[s]) ^
340 int(b >> 32) * int(RMult[s] >> 32))
346 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
347 Bitboard b = blockers & RMask[s];
348 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
353 #if defined(USE_32BIT_ATTACKS)
355 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
356 Bitboard b = blockers & BMask[s];
357 return BAttacks[BAttackIndex[s] +
358 (unsigned(int(b) * int(BMult[s]) ^
359 int(b >> 32) * int(BMult[s] >> 32))
363 #else // defined(USE_32BIT_ATTACKS)
365 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
366 Bitboard b = blockers & BMask[s];
367 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
370 #endif // defined(USE_32BIT_ATTACKS)
372 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
373 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
377 /// squares_between returns a bitboard representing all squares between
378 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
379 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
380 /// on the same line, file or diagonal, EmptyBoardBB is returned.
382 inline Bitboard squares_between(Square s1, Square s2) {
383 return BetweenBB[s1][s2];
387 /// squares_in_front_of takes a color and a square as input, and returns a
388 /// bitboard representing all squares along the line in front of the square,
389 /// from the point of view of the given color. For instance,
390 /// squares_in_front_of(BLACK, SQ_E4) returns a bitboard with the squares
391 /// e3, e2 and e1 set.
393 inline Bitboard squares_in_front_of(Color c, Square s) {
394 return in_front_bb(c, s) & file_bb(s);
398 /// squares_behind is similar to squares_in_front, but returns the squares
399 /// behind the square instead of in front of the square.
401 inline Bitboard squares_behind(Color c, Square s) {
402 return in_front_bb(opposite_color(c), s) & file_bb(s);
406 /// passed_pawn_mask takes a color and a square as input, and returns a
407 /// bitboard mask which can be used to test if a pawn of the given color on
408 /// the given square is a passed pawn.
410 inline Bitboard passed_pawn_mask(Color c, Square s) {
411 return PassedPawnMask[c][s];
415 /// outpost_mask takes a color and a square as input, and returns a bitboard
416 /// mask which can be used to test whether a piece on the square can possibly
417 /// be driven away by an enemy pawn.
419 inline Bitboard outpost_mask(Color c, Square s) {
420 return OutpostMask[c][s];
424 /// isolated_pawn_mask takes a square as input, and returns a bitboard mask
425 /// which can be used to test whether a pawn on the given square is isolated.
427 inline Bitboard isolated_pawn_mask(Square s) {
428 return neighboring_files_bb(s);
432 /// count_1s() counts the number of nonzero bits in a bitboard.
434 #if defined(BITCOUNT_LOOP)
436 inline int count_1s(Bitboard b) {
438 for(r = 0; b; r++, b &= b - 1);
442 inline int count_1s_max_15(Bitboard b) {
446 #elif defined(BITCOUNT_SWAR_32)
448 inline int count_1s(Bitboard b) {
449 unsigned w = unsigned(b >> 32), v = unsigned(b);
450 v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
451 w -= (w >> 1) & 0x55555555;
452 v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
453 w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
454 v = ((v >> 4) + v) & 0x0F0F0F0F; // 0-8 in 8 bits
455 v += (((w >> 4) + w) & 0x0F0F0F0F); // 0-16 in 8 bits
456 v *= 0x01010101; // mul is fast on amd procs
460 inline int count_1s_max_15(Bitboard b) {
461 unsigned w = unsigned(b >> 32), v = unsigned(b);
462 v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
463 w -= (w >> 1) & 0x55555555;
464 v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
465 w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
466 v += w; // 0-8 in 4 bits
471 #elif defined(BITCOUNT_SWAR_64)
473 inline int count_1s(Bitboard b) {
474 b -= ((b>>1) & 0x5555555555555555ULL);
475 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
476 b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
477 b *= 0x0101010101010101ULL;
481 inline int count_1s_max_15(Bitboard b) {
482 b -= (b>>1) & 0x5555555555555555ULL;
483 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
484 b *= 0x1111111111111111ULL;
495 extern void print_bitboard(Bitboard b);
496 extern void init_bitboards();
497 extern Square first_1(Bitboard b);
498 extern Square pop_1st_bit(Bitboard *b);
501 #endif // !defined(BITBOARD_H_INCLUDED)