mirror of
https://github.com/peterosterlund2/droidfish.git
synced 2024-12-04 17:30:56 +01:00
333 lines
9.7 KiB
C++
333 lines
9.7 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef BITBOARD_H_INCLUDED
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#define BITBOARD_H_INCLUDED
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#include <string>
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#include "types.h"
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namespace Bitbases {
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void init();
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bool probe(Square wksq, Square wpsq, Square bksq, Color us);
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}
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namespace Bitboards {
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void init();
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const std::string pretty(Bitboard b);
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}
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const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
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const Bitboard FileABB = 0x0101010101010101ULL;
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const Bitboard FileBBB = FileABB << 1;
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const Bitboard FileCBB = FileABB << 2;
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const Bitboard FileDBB = FileABB << 3;
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const Bitboard FileEBB = FileABB << 4;
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const Bitboard FileFBB = FileABB << 5;
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const Bitboard FileGBB = FileABB << 6;
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const Bitboard FileHBB = FileABB << 7;
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const Bitboard Rank1BB = 0xFF;
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const Bitboard Rank2BB = Rank1BB << (8 * 1);
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const Bitboard Rank3BB = Rank1BB << (8 * 2);
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const Bitboard Rank4BB = Rank1BB << (8 * 3);
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const Bitboard Rank5BB = Rank1BB << (8 * 4);
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const Bitboard Rank6BB = Rank1BB << (8 * 5);
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const Bitboard Rank7BB = Rank1BB << (8 * 6);
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const Bitboard Rank8BB = Rank1BB << (8 * 7);
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extern int SquareDistance[SQUARE_NB][SQUARE_NB];
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extern Bitboard RookMasks [SQUARE_NB];
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extern Bitboard RookMagics [SQUARE_NB];
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extern Bitboard* RookAttacks[SQUARE_NB];
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extern unsigned RookShifts [SQUARE_NB];
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extern Bitboard BishopMasks [SQUARE_NB];
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extern Bitboard BishopMagics [SQUARE_NB];
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extern Bitboard* BishopAttacks[SQUARE_NB];
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extern unsigned BishopShifts [SQUARE_NB];
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extern Bitboard SquareBB[SQUARE_NB];
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extern Bitboard FileBB[FILE_NB];
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extern Bitboard RankBB[RANK_NB];
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extern Bitboard AdjacentFilesBB[FILE_NB];
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extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
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extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
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extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
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extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
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extern Bitboard DistanceRingBB[SQUARE_NB][8];
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extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
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extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
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extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
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extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
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/// Overloads of bitwise operators between a Bitboard and a Square for testing
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/// whether a given bit is set in a bitboard, and for setting and clearing bits.
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inline Bitboard operator&(Bitboard b, Square s) {
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return b & SquareBB[s];
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}
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inline Bitboard operator|(Bitboard b, Square s) {
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return b | SquareBB[s];
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}
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inline Bitboard operator^(Bitboard b, Square s) {
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return b ^ SquareBB[s];
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}
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inline Bitboard& operator|=(Bitboard& b, Square s) {
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return b |= SquareBB[s];
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}
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inline Bitboard& operator^=(Bitboard& b, Square s) {
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return b ^= SquareBB[s];
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}
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inline bool more_than_one(Bitboard b) {
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return b & (b - 1);
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}
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/// rank_bb() and file_bb() return a bitboard representing all the squares on
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/// the given file or rank.
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inline Bitboard rank_bb(Rank r) {
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return RankBB[r];
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}
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inline Bitboard rank_bb(Square s) {
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return RankBB[rank_of(s)];
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}
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inline Bitboard file_bb(File f) {
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return FileBB[f];
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}
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inline Bitboard file_bb(Square s) {
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return FileBB[file_of(s)];
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}
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/// shift_bb() moves a bitboard one step along direction Delta. Mainly for pawns
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template<Square Delta>
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inline Bitboard shift_bb(Bitboard b) {
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return Delta == DELTA_N ? b << 8 : Delta == DELTA_S ? b >> 8
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: Delta == DELTA_NE ? (b & ~FileHBB) << 9 : Delta == DELTA_SE ? (b & ~FileHBB) >> 7
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: Delta == DELTA_NW ? (b & ~FileABB) << 7 : Delta == DELTA_SW ? (b & ~FileABB) >> 9
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: 0;
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}
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/// adjacent_files_bb() returns a bitboard representing all the squares on the
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/// adjacent files of the given one.
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inline Bitboard adjacent_files_bb(File f) {
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return AdjacentFilesBB[f];
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}
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/// between_bb() returns a bitboard representing all the squares between the two
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/// given ones. For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with
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/// the bits for square d5 and e6 set. If s1 and s2 are not on the same rank, file
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/// or diagonal, 0 is returned.
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inline Bitboard between_bb(Square s1, Square s2) {
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return BetweenBB[s1][s2];
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}
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/// in_front_bb() returns a bitboard representing all the squares on all the ranks
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/// in front of the given one, from the point of view of the given color. For
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/// instance, in_front_bb(BLACK, RANK_3) will return the squares on ranks 1 and 2.
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inline Bitboard in_front_bb(Color c, Rank r) {
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return InFrontBB[c][r];
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}
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/// forward_bb() returns a bitboard representing all the squares along the line
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/// in front of the given one, from the point of view of the given color:
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/// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
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inline Bitboard forward_bb(Color c, Square s) {
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return ForwardBB[c][s];
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}
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/// pawn_attack_span() returns a bitboard representing all the squares that can be
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/// attacked by a pawn of the given color when it moves along its file, starting
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/// from the given square:
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/// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
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inline Bitboard pawn_attack_span(Color c, Square s) {
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return PawnAttackSpan[c][s];
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}
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/// passed_pawn_mask() returns a bitboard mask which can be used to test if a
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/// pawn of the given color and on the given square is a passed pawn:
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/// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_bb(c, s)
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inline Bitboard passed_pawn_mask(Color c, Square s) {
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return PassedPawnMask[c][s];
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}
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/// aligned() returns true if the squares s1, s2 and s3 are aligned either on a
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/// straight or on a diagonal line.
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inline bool aligned(Square s1, Square s2, Square s3) {
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return LineBB[s1][s2] & s3;
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}
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/// distance() functions return the distance between x and y, defined as the
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/// number of steps for a king in x to reach y. Works with squares, ranks, files.
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template<typename T> inline int distance(T x, T y) { return x < y ? y - x : x - y; }
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template<> inline int distance<Square>(Square x, Square y) { return SquareDistance[x][y]; }
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template<typename T1, typename T2> inline int distance(T2 x, T2 y);
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template<> inline int distance<File>(Square x, Square y) { return distance(file_of(x), file_of(y)); }
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template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
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/// attacks_bb() returns a bitboard representing all the squares attacked by a
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/// piece of type Pt (bishop or rook) placed on 's'. The helper magic_index()
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/// looks up the index using the 'magic bitboards' approach.
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template<PieceType Pt>
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inline unsigned magic_index(Square s, Bitboard occupied) {
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Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks;
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Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics;
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unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts;
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if (HasPext)
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return unsigned(pext(occupied, Masks[s]));
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if (Is64Bit)
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return unsigned(((occupied & Masks[s]) * Magics[s]) >> Shifts[s]);
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unsigned lo = unsigned(occupied) & unsigned(Masks[s]);
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unsigned hi = unsigned(occupied >> 32) & unsigned(Masks[s] >> 32);
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return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
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}
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template<PieceType Pt>
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inline Bitboard attacks_bb(Square s, Bitboard occupied) {
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return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index<Pt>(s, occupied)];
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}
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inline Bitboard attacks_bb(Piece pc, Square s, Bitboard occupied) {
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switch (type_of(pc))
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{
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case BISHOP: return attacks_bb<BISHOP>(s, occupied);
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case ROOK : return attacks_bb<ROOK>(s, occupied);
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case QUEEN : return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
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default : return StepAttacksBB[pc][s];
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}
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}
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/// lsb() and msb() return the least/most significant bit in a non-zero bitboard
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#ifdef USE_BSFQ
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# if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
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inline Square lsb(Bitboard b) {
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unsigned long idx;
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_BitScanForward64(&idx, b);
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return (Square) idx;
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}
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inline Square msb(Bitboard b) {
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unsigned long idx;
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_BitScanReverse64(&idx, b);
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return (Square) idx;
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}
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# elif defined(__arm__)
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inline int lsb32(uint32_t v) {
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__asm__("rbit %0, %1" : "=r"(v) : "r"(v));
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return __builtin_clz(v);
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}
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inline Square msb(Bitboard b) {
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return (Square) (63 - __builtin_clzll(b));
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}
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inline Square lsb(Bitboard b) {
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return (Square) (uint32_t(b) ? lsb32(uint32_t(b)) : 32 + lsb32(uint32_t(b >> 32)));
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}
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# else // Assumed gcc or compatible compiler
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inline Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen
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Bitboard idx;
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__asm__("bsfq %1, %0": "=r"(idx): "rm"(b) );
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return (Square) idx;
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}
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inline Square msb(Bitboard b) {
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Bitboard idx;
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__asm__("bsrq %1, %0": "=r"(idx): "rm"(b) );
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return (Square) idx;
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}
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# endif
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#else // ifdef(USE_BSFQ)
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Square lsb(Bitboard b);
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Square msb(Bitboard b);
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#endif
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/// pop_lsb() finds and clears the least significant bit in a non-zero bitboard
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inline Square pop_lsb(Bitboard* b) {
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const Square s = lsb(*b);
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*b &= *b - 1;
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return s;
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}
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/// frontmost_sq() and backmost_sq() return the square corresponding to the
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/// most/least advanced bit relative to the given color.
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inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); }
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inline Square backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); }
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#endif // #ifndef BITBOARD_H_INCLUDED
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