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) 2015-2019 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
}
-const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
-
-const Bitboard FileABB = 0x0101010101010101ULL;
-const Bitboard FileBBB = FileABB << 1;
-const Bitboard FileCBB = FileABB << 2;
-const Bitboard FileDBB = FileABB << 3;
-const Bitboard FileEBB = FileABB << 4;
-const Bitboard FileFBB = FileABB << 5;
-const Bitboard FileGBB = FileABB << 6;
-const Bitboard FileHBB = FileABB << 7;
-
-const Bitboard Rank1BB = 0xFF;
-const Bitboard Rank2BB = Rank1BB << (8 * 1);
-const Bitboard Rank3BB = Rank1BB << (8 * 2);
-const Bitboard Rank4BB = Rank1BB << (8 * 3);
-const Bitboard Rank5BB = Rank1BB << (8 * 4);
-const Bitboard Rank6BB = Rank1BB << (8 * 5);
-const Bitboard Rank7BB = Rank1BB << (8 * 6);
-const Bitboard Rank8BB = Rank1BB << (8 * 7);
+constexpr Bitboard AllSquares = ~Bitboard(0);
+constexpr Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
+
+constexpr Bitboard FileABB = 0x0101010101010101ULL;
+constexpr Bitboard FileBBB = FileABB << 1;
+constexpr Bitboard FileCBB = FileABB << 2;
+constexpr Bitboard FileDBB = FileABB << 3;
+constexpr Bitboard FileEBB = FileABB << 4;
+constexpr Bitboard FileFBB = FileABB << 5;
+constexpr Bitboard FileGBB = FileABB << 6;
+constexpr Bitboard FileHBB = FileABB << 7;
+
+constexpr Bitboard Rank1BB = 0xFF;
+constexpr Bitboard Rank2BB = Rank1BB << (8 * 1);
+constexpr Bitboard Rank3BB = Rank1BB << (8 * 2);
+constexpr Bitboard Rank4BB = Rank1BB << (8 * 3);
+constexpr Bitboard Rank5BB = Rank1BB << (8 * 4);
+constexpr Bitboard Rank6BB = Rank1BB << (8 * 5);
+constexpr Bitboard Rank7BB = Rank1BB << (8 * 6);
+constexpr Bitboard Rank8BB = Rank1BB << (8 * 7);
extern int SquareDistance[SQUARE_NB][SQUARE_NB];
extern Bitboard FileBB[FILE_NB];
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 ForwardRanksBB[COLOR_NB][RANK_NB];
extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
extern Bitboard DistanceRingBB[SQUARE_NB][8];
-extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
+extern Bitboard ForwardFileBB[COLOR_NB][SQUARE_NB];
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];
+
+
+/// Magic holds all magic bitboards relevant data for a single square
+struct Magic {
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
+
+ // Compute the attack's index using the 'magic bitboards' approach
+ unsigned index(Bitboard occupied) const {
+
+ if (HasPext)
+ return unsigned(pext(occupied, mask));
+
+ if (Is64Bit)
+ return unsigned(((occupied & mask) * magic) >> shift);
+
+ unsigned lo = unsigned(occupied) & unsigned(mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
+ return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
+ }
+};
+
+extern Magic RookMagics[SQUARE_NB];
+extern Magic BishopMagics[SQUARE_NB];
/// Overloads of bitwise operators between a Bitboard and a Square for testing
/// whether a given bit is set in a bitboard, and for setting and clearing bits.
inline Bitboard operator&(Bitboard b, Square s) {
+ assert(s >= SQ_A1 && s <= SQ_H8);
return b & SquareBB[s];
}
inline Bitboard operator|(Bitboard b, Square s) {
+ assert(s >= SQ_A1 && s <= SQ_H8);
return b | SquareBB[s];
}
inline Bitboard operator^(Bitboard b, Square s) {
+ assert(s >= SQ_A1 && s <= SQ_H8);
return b ^ SquareBB[s];
}
inline Bitboard& operator|=(Bitboard& b, Square s) {
+ assert(s >= SQ_A1 && s <= SQ_H8);
return b |= SquareBB[s];
}
inline Bitboard& operator^=(Bitboard& b, Square s) {
+ assert(s >= SQ_A1 && s <= SQ_H8);
return b ^= SquareBB[s];
}
-inline bool more_than_one(Bitboard b) {
+constexpr bool more_than_one(Bitboard b) {
return b & (b - 1);
}
+inline bool opposite_colors(Square s1, Square s2) {
+ return bool(DarkSquares & s1) != bool(DarkSquares & s2);
+}
/// rank_bb() and file_bb() return a bitboard representing all the squares on
/// the given file or rank.
}
-/// shift() moves a bitboard one step along direction D. Mainly for pawns
+/// shift() moves a bitboard one step along direction D (mainly for pawns)
-template<Square D>
-inline Bitboard shift(Bitboard b) {
+template<Direction D>
+constexpr Bitboard shift(Bitboard b) {
return D == NORTH ? b << 8 : D == SOUTH ? b >> 8
- : D == NORTH_EAST ? (b & ~FileHBB) << 9 : D == SOUTH_EAST ? (b & ~FileHBB) >> 7
- : D == NORTH_WEST ? (b & ~FileABB) << 7 : D == SOUTH_WEST ? (b & ~FileABB) >> 9
+ : D == EAST ? (b & ~FileHBB) << 1 : D == WEST ? (b & ~FileABB) >> 1
+ : D == NORTH_EAST ? (b & ~FileHBB) << 9 : D == NORTH_WEST ? (b & ~FileABB) << 7
+ : D == SOUTH_EAST ? (b & ~FileHBB) >> 7 : D == SOUTH_WEST ? (b & ~FileABB) >> 9
: 0;
}
+/// pawn_attacks_bb() returns the pawn attacks for the given color from the
+/// squares in the given bitboard.
+
+template<Color C>
+constexpr Bitboard pawn_attacks_bb(Bitboard b) {
+ return C == WHITE ? shift<NORTH_WEST>(b) | shift<NORTH_EAST>(b)
+ : shift<SOUTH_WEST>(b) | shift<SOUTH_EAST>(b);
+}
+
+
+/// double_pawn_attacks_bb() returns the pawn attacks for the given color
+/// from the squares in the given bitboard.
+
+template<Color C>
+constexpr Bitboard double_pawn_attacks_bb(Bitboard b) {
+ return C == WHITE ? shift<NORTH_WEST>(b) & shift<NORTH_EAST>(b)
+ : shift<SOUTH_WEST>(b) & shift<SOUTH_EAST>(b);
+}
+
+
/// adjacent_files_bb() returns a bitboard representing all the squares on the
/// adjacent files of the given one.
}
-/// in_front_bb() returns a bitboard representing all the squares on all the ranks
-/// in front of the given one, from the point of view of the given color. For
-/// instance, in_front_bb(BLACK, RANK_3) will return the squares on ranks 1 and 2.
+/// forward_ranks_bb() returns a bitboard representing the squares on all the ranks
+/// in front of the given one, from the point of view of the given color. For instance,
+/// forward_ranks_bb(BLACK, SQ_D3) will return the 16 squares on ranks 1 and 2.
-inline Bitboard in_front_bb(Color c, Rank r) {
- return InFrontBB[c][r];
+inline Bitboard forward_ranks_bb(Color c, Square s) {
+ return ForwardRanksBB[c][rank_of(s)];
}
-/// forward_bb() returns a bitboard representing all the squares along the line
+/// forward_file_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)
+/// ForwardFileBB[c][s] = forward_ranks_bb(c, s) & file_bb(s)
-inline Bitboard forward_bb(Color c, Square s) {
- return ForwardBB[c][s];
+inline Bitboard forward_file_bb(Color c, Square s) {
+ return ForwardFileBB[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] = forward_ranks_bb(c, s) & adjacent_files_bb(file_of(s));
inline Bitboard pawn_attack_span(Color c, Square s) {
return PawnAttackSpan[c][s];
/// passed_pawn_mask() returns a bitboard mask which can be used to test if a
/// pawn of the given color and on the given square is a passed pawn:
-/// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_bb(c, s)
+/// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_file_bb(c, s)
inline Bitboard passed_pawn_mask(Color c, Square s) {
return PassedPawnMask[c][s];
/// 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];
-
- Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks;
- Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics;
- unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts;
-
- if (HasPext)
- return unsigned(pext(occupied, Masks[s]));
-
- if (Is64Bit)
- return unsigned(((occupied & Masks[s]) * Magics[s]) >> Shifts[s]);
-
- 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];
-}
+/// piece of type Pt (bishop or rook) placed on 's'.
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
- extern Bitboard* RookAttacks[SQUARE_NB];
- extern Bitboard* BishopAttacks[SQUARE_NB];
-
- return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index<Pt>(s, occupied)];
+ const Magic& m = Pt == ROOK ? RookMagics[s] : BishopMagics[s];
+ return m.attacks[m.index(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 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];
}
}
/// lsb() and msb() return the least/most significant bit in a non-zero bitboard
-#if defined(__GNUC__)
+#if defined(__GNUC__) // GCC, Clang, ICC
inline Square lsb(Bitboard b) {
assert(b);
return Square(63 ^ __builtin_clzll(b));
}
-#elif defined(_WIN64) && defined(_MSC_VER)
+#elif defined(_MSC_VER) // MSVC
+
+#ifdef _WIN64 // MSVC, WIN64
inline Square lsb(Bitboard b) {
assert(b);
return (Square) idx;
}
-#else
+#else // MSVC, WIN32
+
+inline Square lsb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
+
+ if (b & 0xffffffff) {
+ _BitScanForward(&idx, int32_t(b));
+ return Square(idx);
+ } else {
+ _BitScanForward(&idx, int32_t(b >> 32));
+ return Square(idx + 32);
+ }
+}
+
+inline Square msb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
+
+ if (b >> 32) {
+ _BitScanReverse(&idx, int32_t(b >> 32));
+ return Square(idx + 32);
+ } else {
+ _BitScanReverse(&idx, int32_t(b));
+ return Square(idx);
+ }
+}
+
+#endif
-#define NO_BSF // Fallback on software implementation for other cases
+#else // Compiler is neither GCC nor MSVC compatible
-Square lsb(Bitboard b);
-Square msb(Bitboard b);
+#error "Compiler not supported."
#endif
projects / stockfish / blobdiff