Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
extern Bitboard RankBB[RANK_NB];
extern Bitboard AdjacentFilesBB[FILE_NB];
extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
-extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
extern Bitboard DistanceRingBB[SQUARE_NB][8];
extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
+extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
/// Overloads of bitwise operators between a Bitboard and a Square for testing
/// forward_bb() returns a bitboard representing all the squares along the line
/// in front of the given one, from the point of view of the given color:
-/// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
+/// ForwardBB[c][s] = in_front_bb(c, rank_of(s)) & file_bb(s)
inline Bitboard forward_bb(Color c, Square s) {
return ForwardBB[c][s];
/// pawn_attack_span() returns a bitboard representing all the squares that can be
/// attacked by a pawn of the given color when it moves along its file, starting
/// from the given square:
-/// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
+/// PawnAttackSpan[c][s] = in_front_bb(c, rank_of(s)) & adjacent_files_bb(s);
inline Bitboard pawn_attack_span(Color c, Square s) {
return PawnAttackSpan[c][s];
template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
+/// Magic holds all magic relevant data for a single square
+struct Magic {
+
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
+};
+
/// attacks_bb() returns a bitboard representing all the squares attacked by a
/// piece of type Pt (bishop or rook) placed on 's'. The helper magic_index()
/// looks up the index using the 'magic bitboards' approach.
template<PieceType Pt>
inline unsigned magic_index(Square s, Bitboard occupied) {
- extern Bitboard RookMasks[SQUARE_NB];
- extern Bitboard RookMagics[SQUARE_NB];
- extern unsigned RookShifts[SQUARE_NB];
- extern Bitboard BishopMasks[SQUARE_NB];
- extern Bitboard BishopMagics[SQUARE_NB];
- extern unsigned BishopShifts[SQUARE_NB];
+ extern Magic RookMagics[SQUARE_NB];
+ extern Magic BishopMagics[SQUARE_NB];
- Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks;
- Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics;
- unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts;
+ const Magic* Magics = Pt == ROOK ? RookMagics : BishopMagics;
+ Bitboard mask = Magics[s].mask;
+ Bitboard magic = Magics[s].magic;
+ unsigned shift = Magics[s].shift;
if (HasPext)
- return unsigned(pext(occupied, Masks[s]));
+ return unsigned(pext(occupied, mask));
if (Is64Bit)
- return unsigned(((occupied & Masks[s]) * Magics[s]) >> Shifts[s]);
+ return unsigned(((occupied & mask) * magic) >> shift);
- unsigned lo = unsigned(occupied) & unsigned(Masks[s]);
- unsigned hi = unsigned(occupied >> 32) & unsigned(Masks[s] >> 32);
- return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
+ unsigned lo = unsigned(occupied) & unsigned(mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
+ return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
}
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
- extern Bitboard* RookAttacks[SQUARE_NB];
- extern Bitboard* BishopAttacks[SQUARE_NB];
+ extern Magic RookMagics[SQUARE_NB];
+ extern Magic BishopMagics[SQUARE_NB];
- return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index<Pt>(s, occupied)];
+ return (Pt == ROOK ? RookMagics : BishopMagics)[s].attacks[magic_index<Pt>(s, occupied)];
}
-inline Bitboard attacks_bb(Piece pc, Square s, Bitboard occupied) {
+inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
+
+ assert(pt != PAWN);
- switch (type_of(pc))
+ switch (pt)
{
case BISHOP: return attacks_bb<BISHOP>(s, occupied);
case ROOK : return attacks_bb<ROOK>(s, occupied);
case QUEEN : return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
- default : return StepAttacksBB[pc][s];
+ default : return PseudoAttacks[pt][s];
}
}
inline Square msb(Bitboard b) {
assert(b);
- return Square(63 - __builtin_clzll(b));
+ return Square(63 ^ __builtin_clzll(b));
}
#elif defined(_WIN64) && defined(_MSC_VER)