/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#if !defined(BITBOARD_H_INCLUDED)
+#ifndef BITBOARD_H_INCLUDED
#define BITBOARD_H_INCLUDED
+#include <string>
+
#include "types.h"
-extern Bitboard RMasks[64];
-extern Bitboard RMagics[64];
-extern Bitboard* RAttacks[64];
-extern int RShifts[64];
-
-extern Bitboard BMasks[64];
-extern Bitboard BMagics[64];
-extern Bitboard* BAttacks[64];
-extern int BShifts[64];
-
-extern Bitboard SquareBB[64];
-extern Bitboard FileBB[8];
-extern Bitboard RankBB[8];
-extern Bitboard AdjacentFilesBB[8];
-extern Bitboard ThisAndAdjacentFilesBB[8];
-extern Bitboard InFrontBB[2][8];
-extern Bitboard StepAttacksBB[16][64];
-extern Bitboard BetweenBB[64][64];
-extern Bitboard SquaresInFrontMask[2][64];
-extern Bitboard PassedPawnMask[2][64];
-extern Bitboard AttackSpanMask[2][64];
-extern Bitboard PseudoAttacks[6][64];
-
-
-/// Functions for testing whether a given bit is set in a bitboard, and for
-/// setting and clearing bits.
-
-inline Bitboard bit_is_set(Bitboard b, Square s) {
- return b & SquareBB[s];
+namespace Bitbases {
+
+void init();
+bool probe(Square wksq, Square wpsq, Square bksq, Color us);
+
+}
+
+namespace Bitboards {
+
+void init();
+const std::string pretty(Bitboard b);
+
}
-inline void set_bit(Bitboard* b, Square s) {
- *b |= SquareBB[s];
+const Bitboard AllSquares = ~Bitboard(0);
+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);
+
+extern int SquareDistance[SQUARE_NB][SQUARE_NB];
+
+extern Bitboard SquareBB[SQUARE_NB];
+extern Bitboard FileBB[FILE_NB];
+extern Bitboard RankBB[RANK_NB];
+extern Bitboard AdjacentFilesBB[FILE_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 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) {
+ return b & SquareBB[s];
}
-inline void xor_bit(Bitboard* b, Square s) {
- *b ^= SquareBB[s];
+inline Bitboard operator|(Bitboard b, Square s) {
+ return b | SquareBB[s];
}
+inline Bitboard operator^(Bitboard b, Square s) {
+ return b ^ SquareBB[s];
+}
-/// Functions used to update a bitboard after a move. This is faster
-/// then calling a sequence of clear_bit() + set_bit()
+inline Bitboard& operator|=(Bitboard& b, Square s) {
+ return b |= SquareBB[s];
+}
-inline Bitboard make_move_bb(Square from, Square to) {
- return SquareBB[from] | SquareBB[to];
+inline Bitboard& operator^=(Bitboard& b, Square s) {
+ return b ^= SquareBB[s];
}
-inline void do_move_bb(Bitboard* b, Bitboard move_bb) {
- *b ^= move_bb;
+constexpr bool more_than_one(Bitboard b) {
+ return b & (b - 1);
}
-/// rank_bb() and file_bb() take a file or a square as input and return
-/// a bitboard representing all squares on the given file or rank.
+/// rank_bb() and file_bb() return a bitboard representing all the squares on
+/// the given file or rank.
inline Bitboard rank_bb(Rank r) {
return RankBB[r];
}
-/// adjacent_files_bb takes a file as input and returns a bitboard representing
-/// all squares on the adjacent files.
+/// shift() moves a bitboard one step along direction D. Mainly for pawns
+
+template<Square 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
+ : 0;
+}
+
+
+/// adjacent_files_bb() returns a bitboard representing all the squares on the
+/// adjacent files of the given one.
inline Bitboard adjacent_files_bb(File f) {
return AdjacentFilesBB[f];
}
-/// this_and_adjacent_files_bb takes a file as input and returns a bitboard
-/// representing all squares on the given and adjacent files.
+/// between_bb() returns a bitboard representing all the squares between the two
+/// given ones. For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with
+/// the bits for square d5 and e6 set. If s1 and s2 are not on the same rank, file
+/// or diagonal, 0 is returned.
-inline Bitboard this_and_adjacent_files_bb(File f) {
- return ThisAndAdjacentFilesBB[f];
+inline Bitboard between_bb(Square s1, Square s2) {
+ return BetweenBB[s1][s2];
}
-/// in_front_bb() takes a color and a rank or square as input, and returns a
-/// bitboard representing all the squares on all ranks in front of the rank
-/// (or square), from the given color's point of view. For instance,
-/// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
-/// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
+/// forward_ranks_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, 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)];
}
-inline Bitboard in_front_bb(Color c, Square s) {
- return InFrontBB[c][rank_of(s)];
-}
+/// 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:
+/// ForwardFileBB[c][s] = forward_ranks_bb(c, s) & file_bb(s)
-/// Functions for computing sliding attack bitboards. rook_attacks_bb(),
-/// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
-/// bitboard of occupied squares as input, and return a bitboard representing
-/// all squares attacked by a rook, bishop or queen on the given square.
+inline Bitboard forward_file_bb(Color c, Square s) {
+ return ForwardFileBB[c][s];
+}
-#if defined(IS_64BIT)
-FORCE_INLINE unsigned r_index(Square s, Bitboard occ) {
- return unsigned(((occ & RMasks[s]) * RMagics[s]) >> RShifts[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] = forward_ranks_bb(c, s) & adjacent_files_bb(file_of(s));
-FORCE_INLINE unsigned b_index(Square s, Bitboard occ) {
- return unsigned(((occ & BMasks[s]) * BMagics[s]) >> BShifts[s]);
+inline Bitboard pawn_attack_span(Color c, Square s) {
+ return PawnAttackSpan[c][s];
}
-#else // if !defined(IS_64BIT)
-FORCE_INLINE unsigned r_index(Square s, Bitboard occ) {
- Bitboard b = occ & RMasks[s];
- return unsigned(int(b) * int(RMagics[s]) ^ int(b >> 32) * int(RMagics[s] >> 32)) >> RShifts[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_file_bb(c, s)
-FORCE_INLINE unsigned b_index(Square s, Bitboard occ) {
- Bitboard b = occ & BMasks[s];
- return unsigned(int(b) * int(BMagics[s]) ^ int(b >> 32) * int(BMagics[s] >> 32)) >> BShifts[s];
+inline Bitboard passed_pawn_mask(Color c, Square s) {
+ return PassedPawnMask[c][s];
}
-#endif
-inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
- return RAttacks[s][r_index(s, occ)];
-}
+/// aligned() returns true if the squares s1, s2 and s3 are aligned either on a
+/// straight or on a diagonal line.
-inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
- return BAttacks[s][b_index(s, occ)];
+inline bool aligned(Square s1, Square s2, Square s3) {
+ return LineBB[s1][s2] & s3;
}
-/// squares_between returns a bitboard representing all squares between
-/// two squares. For instance, squares_between(SQ_C4, SQ_F7) returns a
-/// bitboard with the bits for square d5 and e6 set. If s1 and s2 are not
-/// on the same line, file or diagonal, EmptyBoardBB is returned.
+/// distance() functions return the distance between x and y, defined as the
+/// number of steps for a king in x to reach y. Works with squares, ranks, files.
-inline Bitboard squares_between(Square s1, Square s2) {
- return BetweenBB[s1][s2];
-}
+template<typename T> inline int distance(T x, T y) { return x < y ? y - x : x - y; }
+template<> inline int distance<Square>(Square x, Square y) { return SquareDistance[x][y]; }
+template<typename T1, typename T2> inline int distance(T2 x, T2 y);
+template<> inline int distance<File>(Square x, Square y) { return distance(file_of(x), file_of(y)); }
+template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
-/// squares_in_front_of takes a color and a square as input, and returns a
-/// bitboard representing all squares along the line in front of the square,
-/// from the point of view of the given color. Definition of the table is:
-/// SquaresInFrontOf[c][s] = in_front_bb(c, s) & file_bb(s)
-inline Bitboard squares_in_front_of(Color c, Square s) {
- return SquaresInFrontMask[c][s];
+/// attacks_bb() returns a bitboard representing all the squares attacked by a
+/// piece of type Pt (bishop or rook) placed on 's'.
+
+template<PieceType Pt>
+inline Bitboard attacks_bb(Square s, Bitboard occupied) {
+
+ const Magic& m = Pt == ROOK ? RookMagics[s] : BishopMagics[s];
+ return m.attacks[m.index(occupied)];
}
+inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
-/// passed_pawn_mask takes a color and a square as input, and returns a
-/// bitboard mask which can be used to test if a pawn of the given color on
-/// the given square is a passed pawn. Definition of the table is:
-/// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(s)
+ assert(pt != PAWN);
-inline Bitboard passed_pawn_mask(Color c, Square s) {
- return PassedPawnMask[c][s];
+ 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 PseudoAttacks[pt][s];
+ }
}
-/// attack_span_mask takes a color and a square as input, and returns a bitboard
-/// representing all squares that can be attacked by a pawn of the given color
-/// when it moves along its file starting from the given square. Definition is:
-/// AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
+/// popcount() counts the number of non-zero bits in a bitboard
-inline Bitboard attack_span_mask(Color c, Square s) {
- return AttackSpanMask[c][s];
-}
+inline int popcount(Bitboard b) {
+#ifndef USE_POPCNT
-/// squares_aligned returns true if the squares s1, s2 and s3 are aligned
-/// either on a straight or on a diagonal line.
+ extern uint8_t PopCnt16[1 << 16];
+ union { Bitboard bb; uint16_t u[4]; } v = { b };
+ return PopCnt16[v.u[0]] + PopCnt16[v.u[1]] + PopCnt16[v.u[2]] + PopCnt16[v.u[3]];
-inline bool squares_aligned(Square s1, Square s2, Square s3) {
- return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
- & ( SquareBB[s1] | SquareBB[s2] | SquareBB[s3]);
-}
+#elif defined(_MSC_VER) || defined(__INTEL_COMPILER)
+ return (int)_mm_popcnt_u64(b);
-/// same_color_squares() returns a bitboard representing all squares with
-/// the same color of the given square.
+#else // Assumed gcc or compatible compiler
-inline Bitboard same_color_squares(Square s) {
- return bit_is_set(0xAA55AA55AA55AA55ULL, s) ? 0xAA55AA55AA55AA55ULL
- : ~0xAA55AA55AA55AA55ULL;
+ return __builtin_popcountll(b);
+
+#endif
}
-/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
-/// pop_1st_bit() finds and clears the least significant nonzero bit in a
-/// nonzero bitboard.
+/// lsb() and msb() return the least/most significant bit in a non-zero bitboard
-#if defined(USE_BSFQ)
+#if defined(__GNUC__)
-#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
+inline Square lsb(Bitboard b) {
+ assert(b);
+ return Square(__builtin_ctzll(b));
+}
-FORCE_INLINE Square first_1(Bitboard b) {
- unsigned long index;
- _BitScanForward64(&index, b);
- return (Square) index;
+inline Square msb(Bitboard b) {
+ assert(b);
+ return Square(63 ^ __builtin_clzll(b));
}
-#else
-FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
- Bitboard dummy;
- __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
- return (Square) dummy;
+#elif defined(_WIN64) && defined(_MSC_VER)
+
+inline Square lsb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
+ _BitScanForward64(&idx, b);
+ return (Square) idx;
}
-#endif
-FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
- const Square s = first_1(*b);
- *b &= ~(1ULL<<s);
- return s;
+inline Square msb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
+ _BitScanReverse64(&idx, b);
+ return (Square) idx;
}
-#else // if !defined(USE_BSFQ)
+#else
+
+#define NO_BSF // Fallback on software implementation for other cases
-extern Square first_1(Bitboard b);
-extern Square pop_1st_bit(Bitboard* b);
+Square lsb(Bitboard b);
+Square msb(Bitboard b);
#endif
-extern void print_bitboard(Bitboard b);
-extern void bitboards_init();
+/// pop_lsb() finds and clears the least significant bit in a non-zero bitboard
+
+inline Square pop_lsb(Bitboard* b) {
+ const Square s = lsb(*b);
+ *b &= *b - 1;
+ return s;
+}
+
+
+/// frontmost_sq() and backmost_sq() return the square corresponding to the
+/// most/least advanced bit relative to the given color.
+
+inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); }
+inline Square backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); }
-#endif // !defined(BITBOARD_H_INCLUDED)
+#endif // #ifndef BITBOARD_H_INCLUDED
projects / stockfish / blobdiff