X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fbitboard.h;h=390966e3494273969bdb53a50c6953a6c9782611;hb=HEAD;hp=00f0f576d91972762e7f2781a585c3600f371e24;hpb=b1b0c640462aed199a3665e575f9cb208b8e4687;p=stockfish
diff --git a/src/bitboard.h b/src/bitboard.h
index 00f0f576..7dbd5329 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -1,14 +1,12 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
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
@@ -18,276 +16,359 @@
along with this program. If not, see .
*/
-#if !defined(BITBOARD_H_INCLUDED)
+#ifndef BITBOARD_H_INCLUDED
#define BITBOARD_H_INCLUDED
+#include
+#include
+#include
+#include
+#include
+#include
+
#include "types.h"
-const Bitboard EmptyBoardBB = 0;
-
-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 Bitboard SquaresByColorBB[2];
-extern Bitboard FileBB[8];
-extern Bitboard NeighboringFilesBB[8];
-extern Bitboard ThisAndNeighboringFilesBB[8];
-extern Bitboard RankBB[8];
-extern Bitboard InFrontBB[2][8];
-
-extern Bitboard SetMaskBB[65];
-extern Bitboard ClearMaskBB[65];
-
-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 BishopPseudoAttacks[64];
-extern Bitboard RookPseudoAttacks[64];
-extern Bitboard QueenPseudoAttacks[64];
-
-extern uint8_t BitCount8Bit[256];
-
-struct Magics {
- Bitboard mask;
- uint64_t mult;
- uint32_t shift;
- Bitboard* attacks;
-};
+namespace Stockfish {
-extern Magics RMagics[64];
-extern Magics BMagics[64];
+namespace Bitboards {
+void init();
+std::string pretty(Bitboard b);
-/// Functions for testing whether a given bit is set in a bitboard, and for
-/// setting and clearing bits.
+} // namespace Stockfish::Bitboards
-inline Bitboard bit_is_set(Bitboard b, Square s) {
- return b & SetMaskBB[s];
-}
+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;
-inline void set_bit(Bitboard *b, Square s) {
- *b |= SetMaskBB[s];
-}
+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);
-inline void clear_bit(Bitboard *b, Square s) {
- *b &= ClearMaskBB[s];
-}
+extern uint8_t PopCnt16[1 << 16];
+extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
+extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
+extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
-/// Functions used to update a bitboard after a move. This is faster
-/// then calling a sequence of clear_bit() + set_bit()
-inline Bitboard make_move_bb(Square from, Square to) {
- return SetMaskBB[from] | SetMaskBB[to];
-}
+// Magic holds all magic bitboards relevant data for a single square
+struct Magic {
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
-inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
- *b ^= move_bb;
-}
+ // Compute the attack's index using the 'magic bitboards' approach
+ unsigned index(Bitboard occupied) const {
+ if (HasPext)
+ return unsigned(pext(occupied, mask));
-/// 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.
+ if (Is64Bit)
+ return unsigned(((occupied & mask) * magic) >> shift);
-inline Bitboard rank_bb(Rank r) {
- return RankBB[r];
-}
+ unsigned lo = unsigned(occupied) & unsigned(mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
+ return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
+ }
+};
-inline Bitboard rank_bb(Square s) {
- return RankBB[square_rank(s)];
-}
+extern Magic RookMagics[SQUARE_NB];
+extern Magic BishopMagics[SQUARE_NB];
-inline Bitboard file_bb(File f) {
- return FileBB[f];
+inline Bitboard square_bb(Square s) {
+ assert(is_ok(s));
+ return (1ULL << s);
}
-inline Bitboard file_bb(Square s) {
- return FileBB[square_file(s)];
-}
+// 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.
-/// neighboring_files_bb takes a file or a square as input and returns a
-/// bitboard representing all squares on the neighboring files.
+inline Bitboard operator&(Bitboard b, Square s) { return b & square_bb(s); }
+inline Bitboard operator|(Bitboard b, Square s) { return b | square_bb(s); }
+inline Bitboard operator^(Bitboard b, Square s) { return b ^ square_bb(s); }
+inline Bitboard& operator|=(Bitboard& b, Square s) { return b |= square_bb(s); }
+inline Bitboard& operator^=(Bitboard& b, Square s) { return b ^= square_bb(s); }
-inline Bitboard neighboring_files_bb(File f) {
- return NeighboringFilesBB[f];
-}
+inline Bitboard operator&(Square s, Bitboard b) { return b & s; }
+inline Bitboard operator|(Square s, Bitboard b) { return b | s; }
+inline Bitboard operator^(Square s, Bitboard b) { return b ^ s; }
-inline Bitboard neighboring_files_bb(Square s) {
- return NeighboringFilesBB[square_file(s)];
-}
+inline Bitboard operator|(Square s1, Square s2) { return square_bb(s1) | s2; }
+constexpr bool more_than_one(Bitboard b) { return b & (b - 1); }
-/// this_and_neighboring_files_bb takes a file or a square as input and returns
-/// a bitboard representing all squares on the given and neighboring files.
-inline Bitboard this_and_neighboring_files_bb(File f) {
- return ThisAndNeighboringFilesBB[f];
-}
+// rank_bb() and file_bb() return a bitboard representing all the squares on
+// the given file or rank.
-inline Bitboard this_and_neighboring_files_bb(Square s) {
- return ThisAndNeighboringFilesBB[square_file(s)];
-}
+constexpr Bitboard rank_bb(Rank r) { return Rank1BB << (8 * r); }
+constexpr Bitboard rank_bb(Square s) { return rank_bb(rank_of(s)); }
-/// 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.
+constexpr Bitboard file_bb(File f) { return FileABB << f; }
-inline Bitboard in_front_bb(Color c, Rank r) {
- return InFrontBB[c][r];
-}
+constexpr Bitboard file_bb(Square s) { return file_bb(file_of(s)); }
-inline Bitboard in_front_bb(Color c, Square s) {
- return InFrontBB[c][square_rank(s)];
+
+// Moves a bitboard one or two steps as specified by the direction D
+template
+constexpr Bitboard shift(Bitboard b) {
+ return D == NORTH ? b << 8
+ : D == SOUTH ? b >> 8
+ : D == NORTH + NORTH ? b << 16
+ : D == SOUTH + SOUTH ? b >> 16
+ : 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;
}
-/// 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.
+// Returns the squares attacked by pawns of the given color
+// from the squares in the given bitboard.
+template
+constexpr Bitboard pawn_attacks_bb(Bitboard b) {
+ return C == WHITE ? shift(b) | shift(b)
+ : shift(b) | shift(b);
+}
-#if defined(IS_64BIT)
+inline Bitboard pawn_attacks_bb(Color c, Square s) {
-inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
- const Magics& m = RMagics[s];
- return m.attacks[((occ & m.mask) * m.mult) >> m.shift];
+ assert(is_ok(s));
+ return PawnAttacks[c][s];
}
-inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
- const Magics& m = BMagics[s];
- return m.attacks[((occ & m.mask) * m.mult) >> m.shift];
-}
+// Returns a bitboard representing an entire line (from board edge
+// to board edge) that intersects the two given squares. If the given squares
+// are not on a same file/rank/diagonal, the function returns 0. For instance,
+// line_bb(SQ_C4, SQ_F7) will return a bitboard with the A2-G8 diagonal.
+inline Bitboard line_bb(Square s1, Square s2) {
-#else // if !defined(IS_64BIT)
+ assert(is_ok(s1) && is_ok(s2));
-inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
- const Magics& m = RMagics[s];
- Bitboard b = occ & m.mask;
- return m.attacks[(unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift];
+ return LineBB[s1][s2];
}
-inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
- const Magics& m = BMagics[s];
- Bitboard b = occ & m.mask;
- return m.attacks[(unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift];
-}
-#endif
+// Returns a bitboard representing the squares in the semi-open
+// segment between the squares s1 and s2 (excluding s1 but including s2). If the
+// given squares are not on a same file/rank/diagonal, it returns s2. For instance,
+// between_bb(SQ_C4, SQ_F7) will return a bitboard with squares D5, E6 and F7, but
+// between_bb(SQ_E6, SQ_F8) will return a bitboard with the square F8. This trick
+// allows to generate non-king evasion moves faster: the defending piece must either
+// interpose itself to cover the check or capture the checking piece.
+inline Bitboard between_bb(Square s1, Square s2) {
-inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
- return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
+ assert(is_ok(s1) && is_ok(s2));
+
+ return BetweenBB[s1][s2];
}
+// Returns true if the squares s1, s2 and s3 are aligned either on a
+// straight or on a diagonal line.
+inline bool aligned(Square s1, Square s2, Square s3) { return line_bb(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.
-inline Bitboard squares_between(Square s1, Square s2) {
- return BetweenBB[s1][s2];
-}
+// distance() functions return the distance between x and y, defined as the
+// number of steps for a king in x to reach y.
+
+template
+inline int distance(Square x, Square y);
+template<>
+inline int distance(Square x, Square y) {
+ return std::abs(file_of(x) - file_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)
+template<>
+inline int distance(Square x, Square y) {
+ return std::abs(rank_of(x) - rank_of(y));
+}
-inline Bitboard squares_in_front_of(Color c, Square s) {
- return SquaresInFrontMask[c][s];
+template<>
+inline int distance(Square x, Square y) {
+ return SquareDistance[x][y];
}
+inline int edge_distance(File f) { return std::min(f, File(FILE_H - f)); }
+
+// Returns the pseudo attacks of the given piece type
+// assuming an empty board.
+template
+inline Bitboard attacks_bb(Square s) {
-/// 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_neighboring_files_bb(s)
+ assert((Pt != PAWN) && (is_ok(s)));
-inline Bitboard passed_pawn_mask(Color c, Square s) {
- return PassedPawnMask[c][s];
+ 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) & neighboring_files_bb(s);
+// Returns the attacks by the given piece
+// assuming the board is occupied according to the passed Bitboard.
+// Sliding piece attacks do not continue passed an occupied square.
+template
+inline Bitboard attacks_bb(Square s, Bitboard occupied) {
+
+ assert((Pt != PAWN) && (is_ok(s)));
+
+ switch (Pt)
+ {
+ case BISHOP :
+ return BishopMagics[s].attacks[BishopMagics[s].index(occupied)];
+ case ROOK :
+ return RookMagics[s].attacks[RookMagics[s].index(occupied)];
+ case QUEEN :
+ return attacks_bb(s, occupied) | attacks_bb(s, occupied);
+ default :
+ return PseudoAttacks[Pt][s];
+ }
+}
-inline Bitboard attack_span_mask(Color c, Square s) {
- return AttackSpanMask[c][s];
+// Returns the attacks by the given piece
+// assuming the board is occupied according to the passed Bitboard.
+// Sliding piece attacks do not continue passed an occupied square.
+inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
+
+ assert((pt != PAWN) && (is_ok(s)));
+
+ switch (pt)
+ {
+ case BISHOP :
+ return attacks_bb(s, occupied);
+ case ROOK :
+ return attacks_bb(s, occupied);
+ case QUEEN :
+ return attacks_bb(s, occupied) | attacks_bb(s, occupied);
+ default :
+ return PseudoAttacks[pt][s];
+ }
}
-/// squares_aligned returns true if the squares s1, s2 and s3 are aligned
-/// either on a straight or on a diagonal line.
+// Counts the number of non-zero bits in a bitboard.
+inline int popcount(Bitboard b) {
-inline bool squares_aligned(Square s1, Square s2, Square s3) {
- return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
- & ((1ULL << s1) | (1ULL << s2) | (1ULL << s3));
-}
+#ifndef USE_POPCNT
+ 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]];
-/// 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.
+#elif defined(_MSC_VER)
-#if defined(USE_BSFQ)
+ return int(_mm_popcnt_u64(b));
-#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
+#else // Assumed gcc or compatible compiler
-FORCE_INLINE Square first_1(Bitboard b) {
- unsigned long index;
- _BitScanForward64(&index, b);
- return (Square) index;
-}
-#else
+ return __builtin_popcountll(b);
-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;
-}
#endif
+}
-FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
- const Square s = first_1(*b);
- *b &= ~(1ULL<> 32));
+ return Square(idx + 32);
+ }
+ #endif
+#else // Compiler is neither GCC nor MSVC compatible
+ #error "Compiler not supported."
+#endif
}
-#else // if !defined(USE_BSFQ)
+// Returns the most significant bit in a non-zero bitboard.
+inline Square msb(Bitboard b) {
+ assert(b);
+
+#if defined(__GNUC__) // GCC, Clang, ICX
+
+ return Square(63 ^ __builtin_clzll(b));
+
+#elif defined(_MSC_VER)
+ #ifdef _WIN64 // MSVC, WIN64
+
+ unsigned long idx;
+ _BitScanReverse64(&idx, b);
+ return Square(idx);
-extern Square first_1(Bitboard b);
-extern Square pop_1st_bit(Bitboard* b);
+ #else // MSVC, WIN32
+ 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
+#else // Compiler is neither GCC nor MSVC compatible
+ #error "Compiler not supported."
#endif
+}
+// Returns the bitboard of the least significant
+// square of a non-zero bitboard. It is equivalent to square_bb(lsb(bb)).
+inline Bitboard least_significant_square_bb(Bitboard b) {
+ assert(b);
+ return b & -b;
+}
+
+// Finds and clears the least significant bit in a non-zero bitboard.
+inline Square pop_lsb(Bitboard& b) {
+ assert(b);
+ const Square s = lsb(b);
+ b &= b - 1;
+ return s;
+}
-extern void print_bitboard(Bitboard b);
-extern void init_bitboards();
+} // namespace Stockfish
-#endif // !defined(BITBOARD_H_INCLUDED)
+#endif // #ifndef BITBOARD_H_INCLUDED