2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2012 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/>.
21 #if !defined(BITBOARD_H_INCLUDED)
22 #define BITBOARD_H_INCLUDED
26 extern Bitboard FileBB[8];
27 extern Bitboard NeighboringFilesBB[8];
28 extern Bitboard ThisAndNeighboringFilesBB[8];
29 extern Bitboard RankBB[8];
30 extern Bitboard InFrontBB[2][8];
32 extern Bitboard SetMaskBB[65];
33 extern Bitboard ClearMaskBB[65];
35 extern Bitboard StepAttacksBB[16][64];
36 extern Bitboard BetweenBB[64][64];
38 extern Bitboard SquaresInFrontMask[2][64];
39 extern Bitboard PassedPawnMask[2][64];
40 extern Bitboard AttackSpanMask[2][64];
42 extern uint64_t RMagics[64];
43 extern int RShifts[64];
44 extern Bitboard RMasks[64];
45 extern Bitboard* RAttacks[64];
47 extern uint64_t BMagics[64];
48 extern int BShifts[64];
49 extern Bitboard BMasks[64];
50 extern Bitboard* BAttacks[64];
52 extern Bitboard BishopPseudoAttacks[64];
53 extern Bitboard RookPseudoAttacks[64];
54 extern Bitboard QueenPseudoAttacks[64];
56 extern uint8_t BitCount8Bit[256];
59 /// Functions for testing whether a given bit is set in a bitboard, and for
60 /// setting and clearing bits.
62 inline Bitboard bit_is_set(Bitboard b, Square s) {
63 return b & SetMaskBB[s];
66 inline void set_bit(Bitboard* b, Square s) {
70 inline void clear_bit(Bitboard* b, Square s) {
75 /// Functions used to update a bitboard after a move. This is faster
76 /// then calling a sequence of clear_bit() + set_bit()
78 inline Bitboard make_move_bb(Square from, Square to) {
79 return SetMaskBB[from] | SetMaskBB[to];
82 inline void do_move_bb(Bitboard* b, Bitboard move_bb) {
87 /// rank_bb() and file_bb() take a file or a square as input and return
88 /// a bitboard representing all squares on the given file or rank.
90 inline Bitboard rank_bb(Rank r) {
94 inline Bitboard rank_bb(Square s) {
95 return RankBB[rank_of(s)];
98 inline Bitboard file_bb(File f) {
102 inline Bitboard file_bb(Square s) {
103 return FileBB[file_of(s)];
107 /// neighboring_files_bb takes a file as input and returns a bitboard representing
108 /// all squares on the neighboring files.
110 inline Bitboard neighboring_files_bb(File f) {
111 return NeighboringFilesBB[f];
115 /// this_and_neighboring_files_bb takes a file as input and returns a bitboard
116 /// representing all squares on the given and neighboring files.
118 inline Bitboard this_and_neighboring_files_bb(File f) {
119 return ThisAndNeighboringFilesBB[f];
123 /// in_front_bb() takes a color and a rank or square as input, and returns a
124 /// bitboard representing all the squares on all ranks in front of the rank
125 /// (or square), from the given color's point of view. For instance,
126 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
127 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
129 inline Bitboard in_front_bb(Color c, Rank r) {
130 return InFrontBB[c][r];
133 inline Bitboard in_front_bb(Color c, Square s) {
134 return InFrontBB[c][rank_of(s)];
138 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
139 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
140 /// bitboard of occupied squares as input, and return a bitboard representing
141 /// all squares attacked by a rook, bishop or queen on the given square.
143 #if defined(IS_64BIT)
145 FORCE_INLINE unsigned rook_index(Square s, Bitboard occ) {
146 return unsigned(((occ & RMasks[s]) * RMagics[s]) >> RShifts[s]);
149 FORCE_INLINE unsigned bishop_index(Square s, Bitboard occ) {
150 return unsigned(((occ & BMasks[s]) * BMagics[s]) >> BShifts[s]);
153 #else // if !defined(IS_64BIT)
155 FORCE_INLINE unsigned rook_index(Square s, Bitboard occ) {
156 Bitboard b = occ & RMasks[s];
157 return unsigned(int(b) * int(RMagics[s]) ^ int(b >> 32) * int(RMagics[s] >> 32)) >> RShifts[s];
160 FORCE_INLINE unsigned bishop_index(Square s, Bitboard occ) {
161 Bitboard b = occ & BMasks[s];
162 return unsigned(int(b) * int(BMagics[s]) ^ int(b >> 32) * int(BMagics[s] >> 32)) >> BShifts[s];
166 inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
167 return RAttacks[s][rook_index(s, occ)];
170 inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
171 return BAttacks[s][bishop_index(s, occ)];
174 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
175 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
179 /// squares_between returns a bitboard representing all squares between
180 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
181 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
182 /// on the same line, file or diagonal, EmptyBoardBB is returned.
184 inline Bitboard squares_between(Square s1, Square s2) {
185 return BetweenBB[s1][s2];
189 /// squares_in_front_of takes a color and a square as input, and returns a
190 /// bitboard representing all squares along the line in front of the square,
191 /// from the point of view of the given color. Definition of the table is:
192 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
194 inline Bitboard squares_in_front_of(Color c, Square s) {
195 return SquaresInFrontMask[c][s];
199 /// passed_pawn_mask takes a color and a square as input, and returns a
200 /// bitboard mask which can be used to test if a pawn of the given color on
201 /// the given square is a passed pawn. Definition of the table is:
202 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
204 inline Bitboard passed_pawn_mask(Color c, Square s) {
205 return PassedPawnMask[c][s];
209 /// attack_span_mask takes a color and a square as input, and returns a bitboard
210 /// representing all squares that can be attacked by a pawn of the given color
211 /// when it moves along its file starting from the given square. Definition is:
212 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
214 inline Bitboard attack_span_mask(Color c, Square s) {
215 return AttackSpanMask[c][s];
219 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
220 /// either on a straight or on a diagonal line.
222 inline bool squares_aligned(Square s1, Square s2, Square s3) {
223 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
224 & ( SetMaskBB[s1] | SetMaskBB[s2] | SetMaskBB[s3]);
228 /// same_color_squares() returns a bitboard representing all squares with
229 /// the same color of the given square.
231 inline Bitboard same_color_squares(Square s) {
232 return bit_is_set(0xAA55AA55AA55AA55ULL, s) ? 0xAA55AA55AA55AA55ULL
233 : ~0xAA55AA55AA55AA55ULL;
237 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
238 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
239 /// nonzero bitboard.
241 #if defined(USE_BSFQ)
243 #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
245 FORCE_INLINE Square first_1(Bitboard b) {
247 _BitScanForward64(&index, b);
248 return (Square) index;
252 FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
254 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
255 return (Square) dummy;
259 FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
260 const Square s = first_1(*b);
265 #else // if !defined(USE_BSFQ)
267 extern Square first_1(Bitboard b);
268 extern Square pop_1st_bit(Bitboard* b);
273 extern void print_bitboard(Bitboard b);
274 extern void bitboards_init();
276 #endif // !defined(BITBOARD_H_INCLUDED)