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
28 extern Bitboard RMasks[64];
29 extern Bitboard RMagics[64];
30 extern Bitboard* RAttacks[64];
31 extern unsigned RShifts[64];
33 extern Bitboard BMasks[64];
34 extern Bitboard BMagics[64];
35 extern Bitboard* BAttacks[64];
36 extern unsigned BShifts[64];
38 extern Bitboard SquareBB[64];
39 extern Bitboard FileBB[8];
40 extern Bitboard RankBB[8];
41 extern Bitboard AdjacentFilesBB[8];
42 extern Bitboard ThisAndAdjacentFilesBB[8];
43 extern Bitboard InFrontBB[2][8];
44 extern Bitboard StepAttacksBB[16][64];
45 extern Bitboard BetweenBB[64][64];
46 extern Bitboard SquaresInFrontMask[2][64];
47 extern Bitboard PassedPawnMask[2][64];
48 extern Bitboard AttackSpanMask[2][64];
49 extern Bitboard PseudoAttacks[6][64];
52 /// Overloads of bitwise operators between a Bitboard and a Square for testing
53 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
55 inline Bitboard operator&(Bitboard b, Square s) {
56 return b & SquareBB[s];
59 inline Bitboard& operator|=(Bitboard& b, Square s) {
60 return b |= SquareBB[s];
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];
76 /// rank_bb() and file_bb() take a file or a square as input and return
77 /// a bitboard representing all squares on the given file or rank.
79 inline Bitboard rank_bb(Rank r) {
83 inline Bitboard rank_bb(Square s) {
84 return RankBB[rank_of(s)];
87 inline Bitboard file_bb(File f) {
91 inline Bitboard file_bb(Square s) {
92 return FileBB[file_of(s)];
96 /// adjacent_files_bb takes a file as input and returns a bitboard representing
97 /// all squares on the adjacent files.
99 inline Bitboard adjacent_files_bb(File f) {
100 return AdjacentFilesBB[f];
104 /// this_and_adjacent_files_bb takes a file as input and returns a bitboard
105 /// representing all squares on the given and adjacent files.
107 inline Bitboard this_and_adjacent_files_bb(File f) {
108 return ThisAndAdjacentFilesBB[f];
112 /// in_front_bb() takes a color and a rank or square as input, and returns a
113 /// bitboard representing all the squares on all ranks in front of the rank
114 /// (or square), from the given color's point of view. For instance,
115 /// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
116 /// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
118 inline Bitboard in_front_bb(Color c, Rank r) {
119 return InFrontBB[c][r];
122 inline Bitboard in_front_bb(Color c, Square s) {
123 return InFrontBB[c][rank_of(s)];
127 /// Functions for computing sliding attack bitboards. Function attacks_bb() takes
128 /// a square and a bitboard of occupied squares as input, and returns a bitboard
129 /// representing all squares attacked by Pt (bishop or rook) on the given square.
130 template<PieceType Pt>
131 FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
133 Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
134 Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
135 unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
138 return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
140 unsigned lo = unsigned(occ) & unsigned(Masks[s]);
141 unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
142 return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
145 template<PieceType Pt>
146 inline Bitboard attacks_bb(Square s, Bitboard occ) {
147 Bitboard** const Attacks = Pt == ROOK ? RAttacks : BAttacks;
148 return Attacks[s][magic_index<Pt>(s, occ)];
152 /// squares_between returns a bitboard representing all squares between
153 /// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
154 /// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
155 /// on the same line, file or diagonal, EmptyBoardBB is returned.
157 inline Bitboard squares_between(Square s1, Square s2) {
158 return BetweenBB[s1][s2];
162 /// squares_in_front_of takes a color and a square as input, and returns a
163 /// bitboard representing all squares along the line in front of the square,
164 /// from the point of view of the given color. Definition of the table is:
165 /// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
167 inline Bitboard squares_in_front_of(Color c, Square s) {
168 return SquaresInFrontMask[c][s];
172 /// passed_pawn_mask takes a color and a square as input, and returns a
173 /// bitboard mask which can be used to test if a pawn of the given color on
174 /// the given square is a passed pawn. Definition of the table is:
175 /// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(s)
177 inline Bitboard passed_pawn_mask(Color c, Square s) {
178 return PassedPawnMask[c][s];
182 /// attack_span_mask takes a color and a square as input, and returns a bitboard
183 /// representing all squares that can be attacked by a pawn of the given color
184 /// when it moves along its file starting from the given square. Definition is:
185 /// AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
187 inline Bitboard attack_span_mask(Color c, Square s) {
188 return AttackSpanMask[c][s];
192 /// squares_aligned returns true if the squares s1, s2 and s3 are aligned
193 /// either on a straight or on a diagonal line.
195 inline bool squares_aligned(Square s1, Square s2, Square s3) {
196 return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
197 & ( SquareBB[s1] | SquareBB[s2] | SquareBB[s3]);
201 /// same_color_squares() returns a bitboard representing all squares with
202 /// the same color of the given square.
204 inline Bitboard same_color_squares(Square s) {
205 return Bitboard(0xAA55AA55AA55AA55ULL) & s ? 0xAA55AA55AA55AA55ULL
206 : ~0xAA55AA55AA55AA55ULL;
210 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
211 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
212 /// nonzero bitboard.
214 #if defined(USE_BSFQ)
216 #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
218 FORCE_INLINE Square first_1(Bitboard b) {
220 _BitScanForward64(&index, b);
221 return (Square) index;
225 FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
227 __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
228 return (Square) dummy;
232 FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
233 const Square s = first_1(*b);
238 #else // if !defined(USE_BSFQ)
240 extern Square first_1(Bitboard b);
241 extern Square pop_1st_bit(Bitboard* b);
246 extern void print_bitboard(Bitboard b);
247 extern void bitboards_init();
249 #endif // !defined(BITBOARD_H_INCLUDED)