/*
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) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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
#ifndef BITBOARD_H_INCLUDED
#define BITBOARD_H_INCLUDED
+#include <algorithm>
+#include <cassert>
+#include <cmath>
+#include <cstdint>
+#include <cstdlib>
#include <string>
#include "types.h"
-namespace Bitbases {
-
-void init();
-bool probe(Square wksq, Square wpsq, Square bksq, Color us);
-
-}
+namespace Stockfish {
namespace Bitboards {
-void init();
-const std::string pretty(Bitboard b);
-
-}
+void init();
+std::string pretty(Bitboard b);
-constexpr Bitboard AllSquares = ~Bitboard(0);
-constexpr Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
+} // namespace Stockfish::Bitboards
constexpr Bitboard FileABB = 0x0101010101010101ULL;
constexpr Bitboard FileBBB = FileABB << 1;
constexpr Bitboard Rank7BB = Rank1BB << (8 * 6);
constexpr Bitboard Rank8BB = Rank1BB << (8 * 7);
-extern int SquareDistance[SQUARE_NB][SQUARE_NB];
+extern uint8_t PopCnt16[1 << 16];
+extern uint8_t 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
+// Magic holds all magic bitboards relevant data for a single square
struct Magic {
- Bitboard mask;
- Bitboard magic;
- Bitboard* attacks;
- unsigned shift;
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
- // Compute the attack's index using the 'magic bitboards' approach
- unsigned index(Bitboard occupied) const {
+ // Compute the attack's index using the 'magic bitboards' approach
+ unsigned index(Bitboard occupied) const {
- if (HasPext)
- return unsigned(pext(occupied, mask));
+ if (HasPext)
+ return unsigned(pext(occupied, mask));
- if (Is64Bit)
- return unsigned(((occupied & mask) * magic) >> shift);
+ 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;
- }
+ 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 Bitboard square_bb(Square s) {
+ assert(is_ok(s));
+ return (1ULL << s);
}
-inline Bitboard operator|(Bitboard b, Square s) {
- return b | SquareBB[s];
-}
-inline Bitboard operator^(Bitboard b, Square s) {
- return b ^ SquareBB[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.
-inline Bitboard& operator|=(Bitboard& b, Square s) {
- return b |= SquareBB[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& operator^=(Bitboard& b, Square s) { return b ^= square_bb(s); }
-inline Bitboard& operator^=(Bitboard& b, Square s) {
- return b ^= SquareBB[s];
-}
+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; }
-constexpr bool more_than_one(Bitboard b) {
- return b & (b - 1);
-}
+inline Bitboard operator|(Square s1, Square s2) { return square_bb(s1) | s2; }
-/// rank_bb() and file_bb() return a bitboard representing all the squares on
-/// the given file or rank.
+constexpr bool more_than_one(Bitboard b) { return b & (b - 1); }
-inline Bitboard rank_bb(Rank r) {
- return RankBB[r];
-}
-inline Bitboard rank_bb(Square s) {
- return RankBB[rank_of(s)];
-}
+// rank_bb() and file_bb() return a bitboard representing all the squares on
+// the given file or rank.
-inline Bitboard file_bb(File f) {
- return FileBB[f];
-}
+constexpr Bitboard rank_bb(Rank r) { return Rank1BB << (8 * r); }
-inline Bitboard file_bb(Square s) {
- return FileBB[file_of(s)];
-}
+constexpr Bitboard rank_bb(Square s) { return rank_bb(rank_of(s)); }
+constexpr Bitboard file_bb(File f) { return FileABB << f; }
-/// make_bitboard() returns a bitboard from a list of squares
+constexpr Bitboard file_bb(Square s) { return file_bb(file_of(s)); }
-constexpr Bitboard make_bitboard() { return 0; }
-
-template<typename ...Squares>
-constexpr Bitboard make_bitboard(Square s, Squares... squares) {
- return (1ULL << s) | make_bitboard(squares...);
-}
-
-
-/// shift() moves a bitboard one step along direction D (mainly for pawns)
+// Moves a bitboard one or two steps as specified by the direction D
template<Direction D>
constexpr Bitboard shift(Bitboard b) {
- return D == NORTH ? b << 8 : D == SOUTH ? b >> 8
- : 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.
-
+ 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;
+}
+
+
+// Returns the squares attacked by pawns of 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);
+ return C == WHITE ? shift<NORTH_WEST>(b) | shift<NORTH_EAST>(b)
+ : shift<SOUTH_WEST>(b) | shift<SOUTH_EAST>(b);
}
+inline Bitboard pawn_attacks_bb(Color c, Square s) {
-/// 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];
+ assert(is_ok(s));
+ return PawnAttacks[c][s];
}
+// 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) {
-/// 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.
+ assert(is_ok(s1) && is_ok(s2));
-inline Bitboard between_bb(Square s1, Square s2) {
- return BetweenBB[s1][s2];
+ return LineBB[s1][s2];
}
-/// 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 forward_ranks_bb(Color c, Square s) {
- return ForwardRanksBB[c][rank_of(s)];
-}
-
+// 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) {
-/// 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)
+ assert(is_ok(s1) && is_ok(s2));
-inline Bitboard forward_file_bb(Color c, Square s) {
- return ForwardFileBB[c][s];
+ 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; }
-/// 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));
-inline Bitboard pawn_attack_span(Color c, Square s) {
- return PawnAttackSpan[c][s];
-}
+// distance() functions return the distance between x and y, defined as the
+// number of steps for a king in x to reach y.
+template<typename T1 = Square>
+inline int distance(Square x, Square y);
-/// 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)
-
-inline Bitboard passed_pawn_mask(Color c, Square s) {
- return PassedPawnMask[c][s];
+template<>
+inline int distance<File>(Square x, Square y) {
+ return std::abs(file_of(x) - file_of(y));
}
-
-/// aligned() 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 LineBB[s1][s2] & s3;
+template<>
+inline int distance<Rank>(Square x, Square y) {
+ return std::abs(rank_of(x) - rank_of(y));
}
+template<>
+inline int distance<Square>(Square x, Square y) {
+ return SquareDistance[x][y];
+}
-/// 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 int edge_distance(File f) { return std::min(f, File(FILE_H - f)); }
-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]; }
+// Returns the pseudo attacks of the given piece type
+// assuming an empty board.
+template<PieceType Pt>
+inline Bitboard attacks_bb(Square s) {
-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)); }
+ assert((Pt != PAWN) && (is_ok(s)));
+ return PseudoAttacks[Pt][s];
+}
-/// attacks_bb() returns a bitboard representing all the squares attacked by a
-/// piece of type Pt (bishop or rook) placed on '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<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)];
+ 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<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
+ default :
+ return PseudoAttacks[Pt][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);
+ assert((pt != PAWN) && (is_ok(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];
- }
+ 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];
+ }
}
-/// popcount() counts the number of non-zero bits in a bitboard
-
+// Counts the number of non-zero bits in a bitboard.
inline int popcount(Bitboard b) {
#ifndef USE_POPCNT
- 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]];
+ 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]];
-#elif defined(_MSC_VER) || defined(__INTEL_COMPILER)
+#elif defined(_MSC_VER)
- return (int)_mm_popcnt_u64(b);
+ return int(_mm_popcnt_u64(b));
-#else // Assumed gcc or compatible compiler
+#else // Assumed gcc or compatible compiler
- return __builtin_popcountll(b);
+ return __builtin_popcountll(b);
#endif
}
-
-/// lsb() and msb() return the least/most significant bit in a non-zero bitboard
-
-#if defined(__GNUC__) // GCC, Clang, ICC
-
+// Returns the least significant bit in a non-zero bitboard.
inline Square lsb(Bitboard b) {
- assert(b);
- return Square(__builtin_ctzll(b));
-}
-
-inline Square msb(Bitboard b) {
- assert(b);
- return Square(63 ^ __builtin_clzll(b));
-}
+ assert(b);
-#elif defined(_MSC_VER) // MSVC
+#if defined(__GNUC__) // GCC, Clang, ICX
-#ifdef _WIN64 // MSVC, WIN64
+ return Square(__builtin_ctzll(b));
-inline Square lsb(Bitboard b) {
- assert(b);
- unsigned long idx;
- _BitScanForward64(&idx, b);
- return (Square) idx;
-}
+#elif defined(_MSC_VER)
+ #ifdef _WIN64 // MSVC, WIN64
-inline Square msb(Bitboard b) {
- assert(b);
- unsigned long idx;
- _BitScanReverse64(&idx, b);
- return (Square) idx;
-}
+ unsigned long idx;
+ _BitScanForward64(&idx, b);
+ return Square(idx);
-#else // MSVC, WIN32
+ #else // MSVC, WIN32
+ unsigned long idx;
-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);
- }
+ if (b & 0xffffffff)
+ {
+ _BitScanForward(&idx, int32_t(b));
+ return Square(idx);
+ }
+ else
+ {
+ _BitScanForward(&idx, int32_t(b >> 32));
+ return Square(idx + 32);
+ }
+ #endif
+#else // Compiler is neither GCC nor MSVC compatible
+ #error "Compiler not supported."
+#endif
}
+// Returns the most significant bit in a non-zero bitboard.
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);
- }
-}
+ assert(b);
-#endif
+#if defined(__GNUC__) // GCC, Clang, ICX
-#else // Compiler is neither GCC nor MSVC compatible
+ return Square(63 ^ __builtin_clzll(b));
-#error "Compiler not supported."
+#elif defined(_MSC_VER)
+ #ifdef _WIN64 // MSVC, WIN64
-#endif
+ unsigned long idx;
+ _BitScanReverse64(&idx, b);
+ return Square(idx);
+ #else // MSVC, WIN32
-/// pop_lsb() finds and clears the least significant bit in a non-zero bitboard
+ unsigned long idx;
-inline Square pop_lsb(Bitboard* b) {
- const Square s = lsb(*b);
- *b &= *b - 1;
- return s;
+ 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;
+}
-/// frontmost_sq() and backmost_sq() return the square corresponding to the
-/// most/least advanced bit relative to the given color.
+// 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;
+}
-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); }
+} // namespace Stockfish
-#endif // #ifndef BITBOARD_H_INCLUDED
+#endif // #ifndef BITBOARD_H_INCLUDED
projects / stockfish / blobdiff