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;
88 extern const Bitboard SquaresByColorBB[2];
90 const Bitboard FileABB = 0x0101010101010101ULL;
91 const Bitboard FileBBB = 0x0202020202020202ULL;
92 const Bitboard FileCBB = 0x0404040404040404ULL;
93 const Bitboard FileDBB = 0x0808080808080808ULL;
94 const Bitboard FileEBB = 0x1010101010101010ULL;
95 const Bitboard FileFBB = 0x2020202020202020ULL;
96 const Bitboard FileGBB = 0x4040404040404040ULL;
97 const Bitboard FileHBB = 0x8080808080808080ULL;
99 extern const Bitboard FileBB[8];
100 extern const Bitboard NeighboringFilesBB[8];
101 extern const Bitboard ThisAndNeighboringFilesBB[8];
103 const Bitboard Rank1BB = 0xFFULL;
104 const Bitboard Rank2BB = 0xFF00ULL;
105 const Bitboard Rank3BB = 0xFF0000ULL;
106 const Bitboard Rank4BB = 0xFF000000ULL;
107 const Bitboard Rank5BB = 0xFF00000000ULL;
108 const Bitboard Rank6BB = 0xFF0000000000ULL;
109 const Bitboard Rank7BB = 0xFF000000000000ULL;
110 const Bitboard Rank8BB = 0xFF00000000000000ULL;
112 extern const Bitboard RankBB[8];
113 extern const Bitboard RelativeRankBB[2][8];
114 extern const Bitboard InFrontBB[2][8];
116 extern Bitboard SetMaskBB[64];
117 extern Bitboard ClearMaskBB[64];
119 extern Bitboard StepAttackBB[16][64];
120 extern Bitboard RayBB[64][8];
121 extern Bitboard BetweenBB[64][64];
123 extern Bitboard PassedPawnMask[2][64];
124 extern Bitboard OutpostMask[2][64];
126 #if defined(USE_COMPACT_ROOK_ATTACKS)
127 extern Bitboard RankAttacks[8][64], FileAttacks[8][64];
129 extern const uint64_t RMult[64];
130 extern const int RShift[64];
131 extern Bitboard RMask[64];
132 extern int RAttackIndex[64];
133 extern Bitboard RAttacks[0x19000];
134 #endif // defined(USE_COMPACT_ROOK_ATTACKS)
136 extern const uint64_t BMult[64];
137 extern const int BShift[64];
138 extern Bitboard BMask[64];
139 extern int BAttackIndex[64];
140 extern Bitboard BAttacks[0x1480];
142 extern Bitboard BishopPseudoAttacks[64];
143 extern Bitboard RookPseudoAttacks[64];
144 extern Bitboard QueenPseudoAttacks[64];
148 //// Inline functions
151 /// Functions for testing whether a given bit is set in a bitboard, and for
152 /// setting and clearing bits.
154 inline Bitboard bit_is_set(Bitboard b, Square s) {
155 return b & SetMaskBB[s];
158 inline void set_bit(Bitboard *b, Square s) {
162 inline void clear_bit(Bitboard *b, Square s) {
163 *b &= ClearMaskBB[s];
167 /// rank_bb() and file_bb() gives a bitboard containing all squares on a given
168 /// file or rank. It is also possible to pass a square as input to these
171 inline Bitboard rank_bb(Rank r) {
175 inline Bitboard rank_bb(Square s) {
176 return rank_bb(square_rank(s));
179 inline Bitboard file_bb(File f) {
183 inline Bitboard file_bb(Square s) {
184 return file_bb(square_file(s));
188 /// neighboring_files_bb takes a file or a square as input, and returns a
189 /// bitboard representing all squares on the neighboring files.
191 inline Bitboard neighboring_files_bb(File f) {
192 return NeighboringFilesBB[f];
195 inline Bitboard neighboring_files_bb(Square s) {
196 return neighboring_files_bb(square_file(s));
200 /// this_and_neighboring_files_bb takes a file or a square as input, and
201 /// returns a bitboard representing all squares on the given and neighboring
204 inline Bitboard this_and_neighboring_files_bb(File f) {
205 return ThisAndNeighboringFilesBB[f];
208 inline Bitboard this_and_neighboring_files_bb(Square s) {
209 return this_and_neighboring_files_bb(square_file(s));
213 /// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
214 /// representing all squares on the given rank from the given color's point of
215 /// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
216 /// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
219 inline Bitboard relative_rank_bb(Color c, Rank r) {
220 return RelativeRankBB[c][r];
224 /// in_front_bb() takes a color and a rank or square as input, and returns a
225 /// bitboard representing all the squares on all ranks in front of the rank
226 /// (or square), from the given color's point of view. For instance,
227 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
228 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
230 inline Bitboard in_front_bb(Color c, Rank r) {
231 return InFrontBB[c][r];
234 inline Bitboard in_front_bb(Color c, Square s) {
235 return in_front_bb(c, square_rank(s));
239 /// ray_bb() gives a bitboard representing all squares along the ray in a
240 /// given direction from a given square.
242 inline Bitboard ray_bb(Square s, SignedDirection d) {
247 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
248 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
249 /// bitboard of occupied squares as input, and return a bitboard representing
250 /// all squares attacked by a rook, bishop or queen on the given square.
252 #if defined(USE_COMPACT_ROOK_ATTACKS)
254 inline Bitboard file_attacks_bb(Square s, Bitboard blockers) {
255 Bitboard b = (blockers >> square_file(s)) & 0x01010101010100ULL;
257 FileAttacks[square_rank(s)][(b*0xd6e8802041d0c441ULL)>>58] & file_bb(s);
260 inline Bitboard rank_attacks_bb(Square s, Bitboard blockers) {
261 Bitboard b = (blockers >> ((s & 56) + 1)) & 63;
262 return RankAttacks[square_file(s)][b] & rank_bb(s);
265 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
266 return file_attacks_bb(s, blockers) | rank_attacks_bb(s, blockers);
269 #elif defined(USE_32BIT_ATTACKS)
271 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
272 Bitboard b = blockers & RMask[s];
273 return RAttacks[RAttackIndex[s] +
274 (unsigned(int(b) * int(RMult[s]) ^
275 int(b >> 32) * int(RMult[s] >> 32))
281 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
282 Bitboard b = blockers & RMask[s];
283 return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
288 #if defined(USE_32BIT_ATTACKS)
290 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
291 Bitboard b = blockers & BMask[s];
292 return BAttacks[BAttackIndex[s] +
293 (unsigned(int(b) * int(BMult[s]) ^
294 int(b >> 32) * int(BMult[s] >> 32))
298 #else // defined(USE_32BIT_ATTACKS)
300 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
301 Bitboard b = blockers & BMask[s];
302 return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
305 #endif // defined(USE_32BIT_ATTACKS)
307 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
308 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
312 /// squares_between returns a bitboard representing all squares between
313 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
314 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
315 /// on the same line, file or diagonal, EmptyBoardBB is returned.
317 inline Bitboard squares_between(Square s1, Square s2) {
318 return BetweenBB[s1][s2];
322 /// squares_in_front_of takes a color and a square as input, and returns a
323 /// bitboard representing all squares along the line in front of the square,
324 /// from the point of view of the given color. For instance,
325 /// squares_in_front_of(BLACK, SQ_E4) returns a bitboard with the squares
326 /// e3, e2 and e1 set.
328 inline Bitboard squares_in_front_of(Color c, Square s) {
329 return in_front_bb(c, s) & file_bb(s);
333 /// squares_behind is similar to squares_in_front, but returns the squares
334 /// behind the square instead of in front of the square.
336 inline Bitboard squares_behind(Color c, Square s) {
337 return in_front_bb(opposite_color(c), s) & file_bb(s);
341 /// passed_pawn_mask takes a color and a square as input, and returns a
342 /// bitboard mask which can be used to test if a pawn of the given color on
343 /// the given square is a passed pawn.
345 inline Bitboard passed_pawn_mask(Color c, Square s) {
346 return PassedPawnMask[c][s];
350 /// outpost_mask takes a color and a square as input, and returns a bitboard
351 /// mask which can be used to test whether a piece on the square can possibly
352 /// be driven away by an enemy pawn.
354 inline Bitboard outpost_mask(Color c, Square s) {
355 return OutpostMask[c][s];
359 /// isolated_pawn_mask takes a square as input, and returns a bitboard mask
360 /// which can be used to test whether a pawn on the given square is isolated.
362 inline Bitboard isolated_pawn_mask(Square s) {
363 return neighboring_files_bb(s);
367 /// count_1s() counts the number of nonzero bits in a bitboard.
369 #if defined(BITCOUNT_LOOP)
371 inline int count_1s(Bitboard b) {
373 for(r = 0; b; r++, b &= b - 1);
377 inline int count_1s_max_15(Bitboard b) {
381 #elif defined(BITCOUNT_SWAR_32)
383 inline int count_1s(Bitboard b) {
384 unsigned w = unsigned(b >> 32), v = unsigned(b);
385 v = v - ((v >> 1) & 0x55555555);
386 w = w - ((w >> 1) & 0x55555555);
387 v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
388 w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
389 v = (v + (v >> 4)) & 0x0F0F0F0F;
390 w = (w + (w >> 4)) & 0x0F0F0F0F;
391 v = ((v+w) * 0x01010101) >> 24; // mul is fast on amd procs
395 inline int count_1s_max_15(Bitboard b) {
396 unsigned w = unsigned(b >> 32), v = unsigned(b);
397 v = v - ((v >> 1) & 0x55555555);
398 w = w - ((w >> 1) & 0x55555555);
399 v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
400 w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
401 v = ((v+w) * 0x11111111) >> 28;
405 #elif defined(BITCOUNT_SWAR_64)
407 inline int count_1s(Bitboard b) {
408 b -= ((b>>1) & 0x5555555555555555ULL);
409 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
410 b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
411 b *= 0x0101010101010101ULL;
415 inline int count_1s_max_15(Bitboard b) {
416 b -= (b>>1) & 0x5555555555555555ULL;
417 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
418 b *= 0x1111111111111111ULL;
429 extern void print_bitboard(Bitboard b);
430 extern void init_bitboards();
431 extern Square first_1(Bitboard b);
432 extern Square pop_1st_bit(Bitboard *b);
435 #endif // !defined(BITBOARD_H_INCLUDED)