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 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 /// rank_bb() and file_bb() gives a bitboard containing all squares on a given
209 /// file or rank. It is also possible to pass a square as input to these
212 inline Bitboard rank_bb(Rank r) {
216 inline Bitboard rank_bb(Square s) {
217 return rank_bb(square_rank(s));
220 inline Bitboard file_bb(File f) {
224 inline Bitboard file_bb(Square s) {
225 return file_bb(square_file(s));
229 /// neighboring_files_bb takes a file or a square as input, and returns a
230 /// bitboard representing all squares on the neighboring files.
232 inline Bitboard neighboring_files_bb(File f) {
233 return NeighboringFilesBB[f];
236 inline Bitboard neighboring_files_bb(Square s) {
237 return neighboring_files_bb(square_file(s));
241 /// this_and_neighboring_files_bb takes a file or a square as input, and
242 /// returns a bitboard representing all squares on the given and neighboring
245 inline Bitboard this_and_neighboring_files_bb(File f) {
246 return ThisAndNeighboringFilesBB[f];
249 inline Bitboard this_and_neighboring_files_bb(Square s) {
250 return this_and_neighboring_files_bb(square_file(s));
254 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
255 /// representing all squares on the given rank from the given color's point of
256 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
257 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
260 inline Bitboard relative_rank_bb(Color c, Rank r) {
261 return RelativeRankBB[c][r];
265 /// in_front_bb() takes a color and a rank or square as input, and returns a
266 /// bitboard representing all the squares on all ranks in front of the rank
267 /// (or square), from the given color's point of view. For instance,
268 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
269 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
271 inline Bitboard in_front_bb(Color c, Rank r) {
272 return InFrontBB[c][r];
275 inline Bitboard in_front_bb(Color c, Square s) {
276 return in_front_bb(c, square_rank(s));
280 /// behind_bb() takes a color and a rank or square as input, and returns a
281 /// bitboard representing all the squares on all ranks behind of the rank
282 /// (or square), from the given color's point of view.
284 inline Bitboard behind_bb(Color c, Rank r) {
285 return InFrontBB[opposite_color(c)][r];
288 inline Bitboard behind_bb(Color c, Square s) {
289 return in_front_bb(opposite_color(c), square_rank(s));
293 /// ray_bb() gives a bitboard representing all squares along the ray in a
294 /// given direction from a given square.
296 inline Bitboard ray_bb(Square s, SignedDirection d) {
301 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
302 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
303 /// bitboard of occupied squares as input, and return a bitboard representing
304 /// all squares attacked by a rook, bishop or queen on the given square.
306 #if defined(USE_COMPACT_ROOK_ATTACKS)
308 inline Bitboard file_attacks_bb(Square s, Bitboard blockers) {
309 Bitboard b = (blockers >> square_file(s)) & 0x01010101010100ULL;
311 FileAttacks[square_rank(s)][(b*0xd6e8802041d0c441ULL)>>58] & file_bb(s);
314 inline Bitboard rank_attacks_bb(Square s, Bitboard blockers) {
315 Bitboard b = (blockers >> ((s & 56) + 1)) & 63;
316 return RankAttacks[square_file(s)][b] & rank_bb(s);
319 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
320 return file_attacks_bb(s, blockers) | rank_attacks_bb(s, blockers);
323 #elif defined(USE_32BIT_ATTACKS)
325 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
326 Bitboard b = blockers & RMask[s];
327 return RAttacks[RAttackIndex[s] +
328 (unsigned(int(b) * int(RMult[s]) ^
329 int(b >> 32) * int(RMult[s] >> 32))
335 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
336 Bitboard b = blockers & RMask[s];
337 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
342 #if defined(USE_32BIT_ATTACKS)
344 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
345 Bitboard b = blockers & BMask[s];
346 return BAttacks[BAttackIndex[s] +
347 (unsigned(int(b) * int(BMult[s]) ^
348 int(b >> 32) * int(BMult[s] >> 32))
352 #else // defined(USE_32BIT_ATTACKS)
354 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
355 Bitboard b = blockers & BMask[s];
356 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
359 #endif // defined(USE_32BIT_ATTACKS)
361 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
362 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
366 /// squares_between returns a bitboard representing all squares between
367 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
368 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
369 /// on the same line, file or diagonal, EmptyBoardBB is returned.
371 inline Bitboard squares_between(Square s1, Square s2) {
372 return BetweenBB[s1][s2];
376 /// squares_in_front_of takes a color and a square as input, and returns a
377 /// bitboard representing all squares along the line in front of the square,
378 /// from the point of view of the given color. For instance,
379 /// squares_in_front_of(BLACK, SQ_E4) returns a bitboard with the squares
380 /// e3, e2 and e1 set.
382 inline Bitboard squares_in_front_of(Color c, Square s) {
383 return in_front_bb(c, s) & file_bb(s);
387 /// squares_behind is similar to squares_in_front, but returns the squares
388 /// behind the square instead of in front of the square.
390 inline Bitboard squares_behind(Color c, Square s) {
391 return in_front_bb(opposite_color(c), s) & file_bb(s);
395 /// passed_pawn_mask takes a color and a square as input, and returns a
396 /// bitboard mask which can be used to test if a pawn of the given color on
397 /// the given square is a passed pawn.
399 inline Bitboard passed_pawn_mask(Color c, Square s) {
400 return PassedPawnMask[c][s];
404 /// outpost_mask takes a color and a square as input, and returns a bitboard
405 /// mask which can be used to test whether a piece on the square can possibly
406 /// be driven away by an enemy pawn.
408 inline Bitboard outpost_mask(Color c, Square s) {
409 return OutpostMask[c][s];
413 /// isolated_pawn_mask takes a square as input, and returns a bitboard mask
414 /// which can be used to test whether a pawn on the given square is isolated.
416 inline Bitboard isolated_pawn_mask(Square s) {
417 return neighboring_files_bb(s);
421 /// count_1s() counts the number of nonzero bits in a bitboard.
423 #if defined(BITCOUNT_LOOP)
425 inline int count_1s(Bitboard b) {
427 for(r = 0; b; r++, b &= b - 1);
431 inline int count_1s_max_15(Bitboard b) {
435 #elif defined(BITCOUNT_SWAR_32)
437 inline int count_1s(Bitboard b) {
438 unsigned w = unsigned(b >> 32), v = unsigned(b);
439 v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
440 w -= (w >> 1) & 0x55555555;
441 v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
442 w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
443 v = ((v >> 4) + v) & 0x0F0F0F0F; // 0-8 in 8 bits
444 v += (((w >> 4) + w) & 0x0F0F0F0F); // 0-16 in 8 bits
445 v *= 0x01010101; // mul is fast on amd procs
449 inline int count_1s_max_15(Bitboard b) {
450 unsigned w = unsigned(b >> 32), v = unsigned(b);
451 v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
452 w -= (w >> 1) & 0x55555555;
453 v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
454 w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
455 v += w; // 0-8 in 4 bits
460 #elif defined(BITCOUNT_SWAR_64)
462 inline int count_1s(Bitboard b) {
463 b -= ((b>>1) & 0x5555555555555555ULL);
464 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
465 b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
466 b *= 0x0101010101010101ULL;
470 inline int count_1s_max_15(Bitboard b) {
471 b -= (b>>1) & 0x5555555555555555ULL;
472 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
473 b *= 0x1111111111111111ULL;
484 extern void print_bitboard(Bitboard b);
485 extern void init_bitboards();
486 extern Square first_1(Bitboard b);
487 extern Square pop_1st_bit(Bitboard *b);
490 #endif // !defined(BITBOARD_H_INCLUDED)