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/>.
21 #if !defined(BITBOARD_H_INCLUDED)
22 #define BITBOARD_H_INCLUDED
26 extern Bitboard SquaresByColorBB[2];
27 extern Bitboard FileBB[8];
28 extern Bitboard NeighboringFilesBB[8];
29 extern Bitboard ThisAndNeighboringFilesBB[8];
30 extern Bitboard RankBB[8];
31 extern Bitboard InFrontBB[2][8];
33 extern Bitboard SetMaskBB[65];
34 extern Bitboard ClearMaskBB[65];
36 extern Bitboard StepAttacksBB[16][64];
37 extern Bitboard BetweenBB[64][64];
39 extern Bitboard SquaresInFrontMask[2][64];
40 extern Bitboard PassedPawnMask[2][64];
41 extern Bitboard AttackSpanMask[2][64];
43 extern uint64_t RMagics[64];
44 extern int RShifts[64];
45 extern Bitboard RMasks[64];
46 extern Bitboard* RAttacks[64];
48 extern uint64_t BMagics[64];
49 extern int BShifts[64];
50 extern Bitboard BMasks[64];
51 extern Bitboard* BAttacks[64];
53 extern Bitboard BishopPseudoAttacks[64];
54 extern Bitboard RookPseudoAttacks[64];
55 extern Bitboard QueenPseudoAttacks[64];
57 extern uint8_t BitCount8Bit[256];
60 /// Functions for testing whether a given bit is set in a bitboard, and for
61 /// setting and clearing bits.
63 inline Bitboard bit_is_set(Bitboard b, Square s) {
64 return b & SetMaskBB[s];
67 inline void set_bit(Bitboard* b, Square s) {
71 inline void clear_bit(Bitboard* b, Square s) {
76 /// Functions used to update a bitboard after a move. This is faster
77 /// then calling a sequence of clear_bit() + set_bit()
79 inline Bitboard make_move_bb(Square from, Square to) {
80 return SetMaskBB[from] | SetMaskBB[to];
83 inline void do_move_bb(Bitboard* b, Bitboard move_bb) {
88 /// rank_bb() and file_bb() take a file or a square as input and return
89 /// a bitboard representing all squares on the given file or rank.
91 inline Bitboard rank_bb(Rank r) {
95 inline Bitboard rank_bb(Square s) {
96 return RankBB[rank_of(s)];
99 inline Bitboard file_bb(File f) {
103 inline Bitboard file_bb(Square s) {
104 return FileBB[file_of(s)];
108 /// neighboring_files_bb takes a file as input and returns a bitboard representing
109 /// all squares on the neighboring files.
111 inline Bitboard neighboring_files_bb(File f) {
112 return NeighboringFilesBB[f];
116 /// this_and_neighboring_files_bb takes a file as input and returns a bitboard
117 /// representing all squares on the given and neighboring files.
119 inline Bitboard this_and_neighboring_files_bb(File f) {
120 return ThisAndNeighboringFilesBB[f];
124 /// in_front_bb() takes a color and a rank or square as input, and returns a
125 /// bitboard representing all the squares on all ranks in front of the rank
126 /// (or square), from the given color's point of view. For instance,
127 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
128 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
130 inline Bitboard in_front_bb(Color c, Rank r) {
131 return InFrontBB[c][r];
134 inline Bitboard in_front_bb(Color c, Square s) {
135 return InFrontBB[c][rank_of(s)];
139 /// Functions for computing sliding attack bitboards. rook_attacks_bb(),
140 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
141 /// bitboard of occupied squares as input, and return a bitboard representing
142 /// all squares attacked by a rook, bishop or queen on the given square.
144 #if defined(IS_64BIT)
146 FORCE_INLINE unsigned rook_index(Square s, Bitboard occ) {
147 return unsigned(((occ & RMasks[s]) * RMagics[s]) >> RShifts[s]);
150 FORCE_INLINE unsigned bishop_index(Square s, Bitboard occ) {
151 return unsigned(((occ & BMasks[s]) * BMagics[s]) >> BShifts[s]);
154 #else // if !defined(IS_64BIT)
156 FORCE_INLINE unsigned rook_index(Square s, Bitboard occ) {
157 Bitboard b = occ & RMasks[s];
158 return unsigned(int(b) * int(RMagics[s]) ^ int(b >> 32) * int(RMagics[s] >> 32)) >> RShifts[s];
161 FORCE_INLINE unsigned bishop_index(Square s, Bitboard occ) {
162 Bitboard b = occ & BMasks[s];
163 return unsigned(int(b) * int(BMagics[s]) ^ int(b >> 32) * int(BMagics[s] >> 32)) >> BShifts[s];
167 inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
168 return RAttacks[s][rook_index(s, occ)];
171 inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
172 return BAttacks[s][bishop_index(s, occ)];
175 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
176 return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
180 /// squares_between returns a bitboard representing all squares between
181 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
182 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
183 /// on the same line, file or diagonal, EmptyBoardBB is returned.
185 inline Bitboard squares_between(Square s1, Square s2) {
186 return BetweenBB[s1][s2];
190 /// squares_in_front_of takes a color and a square as input, and returns a
191 /// bitboard representing all squares along the line in front of the square,
192 /// from the point of view of the given color. Definition of the table is:
193 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
195 inline Bitboard squares_in_front_of(Color c, Square s) {
196 return SquaresInFrontMask[c][s];
200 /// passed_pawn_mask takes a color and a square as input, and returns a
201 /// bitboard mask which can be used to test if a pawn of the given color on
202 /// the given square is a passed pawn. Definition of the table is:
203 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s)
205 inline Bitboard passed_pawn_mask(Color c, Square s) {
206 return PassedPawnMask[c][s];
210 /// attack_span_mask takes a color and a square as input, and returns a bitboard
211 /// representing all squares that can be attacked by a pawn of the given color
212 /// when it moves along its file starting from the given square. Definition is:
213 /// AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
215 inline Bitboard attack_span_mask(Color c, Square s) {
216 return AttackSpanMask[c][s];
220 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
221 /// either on a straight or on a diagonal line.
223 inline bool squares_aligned(Square s1, Square s2, Square s3) {
224 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
225 & ( SetMaskBB[s1] | SetMaskBB[s2] | SetMaskBB[s3]);
229 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
230 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
231 /// nonzero bitboard.
233 #if defined(USE_BSFQ)
235 #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
237 FORCE_INLINE Square first_1(Bitboard b) {
239 _BitScanForward64(&index, b);
240 return (Square) index;
244 FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
246 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
247 return (Square) dummy;
251 FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
252 const Square s = first_1(*b);
257 #else // if !defined(USE_BSFQ)
259 extern Square first_1(Bitboard b);
260 extern Square pop_1st_bit(Bitboard* b);
265 extern void print_bitboard(Bitboard b);
266 extern void bitboards_init();
268 #endif // !defined(BITBOARD_H_INCLUDED)