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
29 extern void print(Bitboard b);
35 extern Bitboard RMasks[64];
36 extern Bitboard RMagics[64];
37 extern Bitboard* RAttacks[64];
38 extern unsigned RShifts[64];
40 extern Bitboard BMasks[64];
41 extern Bitboard BMagics[64];
42 extern Bitboard* BAttacks[64];
43 extern unsigned BShifts[64];
45 extern Bitboard SquareBB[64];
46 extern Bitboard FileBB[8];
47 extern Bitboard RankBB[8];
48 extern Bitboard AdjacentFilesBB[8];
49 extern Bitboard ThisAndAdjacentFilesBB[8];
50 extern Bitboard InFrontBB[2][8];
51 extern Bitboard StepAttacksBB[16][64];
52 extern Bitboard BetweenBB[64][64];
53 extern Bitboard DistanceRingsBB[64][8];
54 extern Bitboard ForwardBB[2][64];
55 extern Bitboard PassedPawnMask[2][64];
56 extern Bitboard AttackSpanMask[2][64];
57 extern Bitboard PseudoAttacks[6][64];
60 /// Overloads of bitwise operators between a Bitboard and a Square for testing
61 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
63 inline Bitboard operator&(Bitboard b, Square s) {
64 return b & SquareBB[s];
67 inline Bitboard& operator|=(Bitboard& b, Square s) {
68 return b |= SquareBB[s];
71 inline Bitboard& operator^=(Bitboard& b, Square s) {
72 return b ^= SquareBB[s];
75 inline Bitboard operator|(Bitboard b, Square s) {
76 return b | SquareBB[s];
79 inline Bitboard operator^(Bitboard b, Square s) {
80 return b ^ SquareBB[s];
84 /// more_than_one() returns true if in 'b' there is more than one bit set
86 inline bool more_than_one(Bitboard b) {
91 /// rank_bb() and file_bb() take a file or a square as input and return
92 /// a bitboard representing all squares on the given file or rank.
94 inline Bitboard rank_bb(Rank r) {
98 inline Bitboard rank_bb(Square s) {
99 return RankBB[rank_of(s)];
102 inline Bitboard file_bb(File f) {
106 inline Bitboard file_bb(Square s) {
107 return FileBB[file_of(s)];
111 /// adjacent_files_bb takes a file as input and returns a bitboard representing
112 /// all squares on the adjacent files.
114 inline Bitboard adjacent_files_bb(File f) {
115 return AdjacentFilesBB[f];
119 /// this_and_adjacent_files_bb takes a file as input and returns a bitboard
120 /// representing all squares on the given and adjacent files.
122 inline Bitboard this_and_adjacent_files_bb(File f) {
123 return ThisAndAdjacentFilesBB[f];
127 /// in_front_bb() takes a color and a rank or square as input, and returns a
128 /// bitboard representing all the squares on all ranks in front of the rank
129 /// (or square), from the given color's point of view. For instance,
130 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
131 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
133 inline Bitboard in_front_bb(Color c, Rank r) {
134 return InFrontBB[c][r];
137 inline Bitboard in_front_bb(Color c, Square s) {
138 return InFrontBB[c][rank_of(s)];
142 /// between_bb returns a bitboard representing all squares between two squares.
143 /// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
144 /// square d5 and e6 set. If s1 and s2 are not on the same line, file or diagonal,
147 inline Bitboard between_bb(Square s1, Square s2) {
148 return BetweenBB[s1][s2];
152 /// forward_bb takes a color and a square as input, and returns a bitboard
153 /// representing all squares along the line in front of the square, from the
154 /// point of view of the given color. Definition of the table is:
155 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
157 inline Bitboard forward_bb(Color c, Square s) {
158 return ForwardBB[c][s];
162 /// passed_pawn_mask takes a color and a square as input, and returns a
163 /// bitboard mask which can be used to test if a pawn of the given color on
164 /// the given square is a passed pawn. Definition of the table is:
165 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(s)
167 inline Bitboard passed_pawn_mask(Color c, Square s) {
168 return PassedPawnMask[c][s];
172 /// attack_span_mask takes a color and a square as input, and returns a bitboard
173 /// representing all squares that can be attacked by a pawn of the given color
174 /// when it moves along its file starting from the given square. Definition is:
175 /// AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
177 inline Bitboard attack_span_mask(Color c, Square s) {
178 return AttackSpanMask[c][s];
182 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
183 /// either on a straight or on a diagonal line.
185 inline bool squares_aligned(Square s1, Square s2, Square s3) {
186 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
187 & ( SquareBB[s1] | SquareBB[s2] | SquareBB[s3]);
191 /// same_color_squares() returns a bitboard representing all squares with
192 /// the same color of the given square.
194 inline Bitboard same_color_squares(Square s) {
195 return Bitboard(0xAA55AA55AA55AA55ULL) & s ? 0xAA55AA55AA55AA55ULL
196 : ~0xAA55AA55AA55AA55ULL;
200 /// Functions for computing sliding attack bitboards. Function attacks_bb() takes
201 /// a square and a bitboard of occupied squares as input, and returns a bitboard
202 /// representing all squares attacked by Pt (bishop or rook) on the given square.
203 template<PieceType Pt>
204 FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
206 Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
207 Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
208 unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
211 return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
213 unsigned lo = unsigned(occ) & unsigned(Masks[s]);
214 unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
215 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
218 template<PieceType Pt>
219 inline Bitboard attacks_bb(Square s, Bitboard occ) {
220 return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
224 /// lsb()/msb() finds the least/most significant bit in a nonzero bitboard.
225 /// pop_lsb() finds and clears the least significant bit in a nonzero bitboard.
227 #if defined(USE_BSFQ)
229 # if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
231 FORCE_INLINE Square lsb(Bitboard b) {
233 _BitScanForward64(&index, b);
234 return (Square) index;
237 FORCE_INLINE Square msb(Bitboard b) {
239 _BitScanReverse64(&index, b);
240 return (Square) index;
245 FORCE_INLINE Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen
247 __asm__("bsfq %1, %0": "=r"(index): "rm"(b) );
248 return (Square) index;
251 FORCE_INLINE Square msb(Bitboard b) {
253 __asm__("bsrq %1, %0": "=r"(index): "rm"(b) );
254 return (Square) index;
259 FORCE_INLINE Square pop_lsb(Bitboard* b) {
260 const Square s = lsb(*b);
265 #else // if !defined(USE_BSFQ)
267 extern Square msb(Bitboard b);
268 extern Square lsb(Bitboard b);
269 extern Square pop_lsb(Bitboard* b);
273 #endif // !defined(BITBOARD_H_INCLUDED)