X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.h;h=859fc958c88f60b8c88d4375fe1f53503ac3be7b;hp=1aefd8add5a623729652f70fc21a45076aacb5ee;hb=4006f2c9132db034a27a94be33070d6aaab75b24;hpb=c32904f0a049491585a043f95716f5b2c2678825
diff --git a/src/bitboard.h b/src/bitboard.h
index 1aefd8ad..afeb40ec 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -1,14 +1,14 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2020 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
@@ -18,432 +18,427 @@
along with this program. If not, see .
*/
-
-#if !defined(BITBOARD_H_INCLUDED)
+#ifndef BITBOARD_H_INCLUDED
#define BITBOARD_H_INCLUDED
+#include
-////
-//// Defines
-////
-
-// Comment following define if you prefer manually adjust
-// platform macros defined below
-#define AUTO_CONFIGURATION
+#include "types.h"
-// Quiet a warning on Intel compiler
-#if !defined(__SIZEOF_INT__ )
-#define __SIZEOF_INT__ 0
-#endif
+namespace Bitbases {
-// Check for 64 bits for different compilers: Intel, MSVC and gcc
-#if defined(__x86_64) || defined(_WIN64) || (__SIZEOF_INT__ > 4)
-#define IS_64BIT
-#endif
+void init();
+bool probe(Square wksq, Square wpsq, Square bksq, Color us);
-#if !defined(AUTO_CONFIGURATION) || defined(IS_64BIT)
+}
-//#define USE_COMPACT_ROOK_ATTACKS
-//#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
+namespace Bitboards {
-#define BITCOUNT_SWAR_64
-//#define BITCOUNT_SWAR_32
-//#define BITCOUNT_LOOP
+void init();
+const std::string pretty(Bitboard b);
-#else
+}
-#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
-#define BITCOUNT_SWAR_32
+constexpr Bitboard AllSquares = ~Bitboard(0);
+constexpr Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
-#endif
+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;
-////
-//// Includes
-////
+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);
-#include "direction.h"
-#include "piece.h"
-#include "square.h"
-#include "types.h"
+constexpr Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
+constexpr Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+constexpr Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
+constexpr Bitboard Center = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
+constexpr Bitboard KingFlank[FILE_NB] = {
+ QueenSide ^ FileDBB, QueenSide, QueenSide,
+ CenterFiles, CenterFiles,
+ KingSide, KingSide, KingSide ^ FileEBB
+};
-////
-//// Types
-////
+extern uint8_t PopCnt16[1 << 16];
+extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
-typedef uint64_t Bitboard;
+extern Bitboard SquareBB[SQUARE_NB];
+extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
+extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
-////
-//// Constants and variables
-////
+/// Magic holds all magic bitboards relevant data for a single square
+struct Magic {
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
-const Bitboard EmptyBoardBB = 0ULL;
+ // Compute the attack's index using the 'magic bitboards' approach
+ unsigned index(Bitboard occupied) const {
-const Bitboard WhiteSquaresBB = 0x55AA55AA55AA55AAULL;
-const Bitboard BlackSquaresBB = 0xAA55AA55AA55AA55ULL;
+ if (HasPext)
+ return unsigned(pext(occupied, mask));
-extern const Bitboard SquaresByColorBB[2];
+ if (Is64Bit)
+ return unsigned(((occupied & mask) * magic) >> shift);
-const Bitboard FileABB = 0x0101010101010101ULL;
-const Bitboard FileBBB = 0x0202020202020202ULL;
-const Bitboard FileCBB = 0x0404040404040404ULL;
-const Bitboard FileDBB = 0x0808080808080808ULL;
-const Bitboard FileEBB = 0x1010101010101010ULL;
-const Bitboard FileFBB = 0x2020202020202020ULL;
-const Bitboard FileGBB = 0x4040404040404040ULL;
-const Bitboard FileHBB = 0x8080808080808080ULL;
+ unsigned lo = unsigned(occupied) & unsigned(mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
+ return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
+ }
+};
-extern const Bitboard FileBB[8];
-extern const Bitboard NeighboringFilesBB[8];
-extern const Bitboard ThisAndNeighboringFilesBB[8];
+extern Magic RookMagics[SQUARE_NB];
+extern Magic BishopMagics[SQUARE_NB];
-const Bitboard Rank1BB = 0xFFULL;
-const Bitboard Rank2BB = 0xFF00ULL;
-const Bitboard Rank3BB = 0xFF0000ULL;
-const Bitboard Rank4BB = 0xFF000000ULL;
-const Bitboard Rank5BB = 0xFF00000000ULL;
-const Bitboard Rank6BB = 0xFF0000000000ULL;
-const Bitboard Rank7BB = 0xFF000000000000ULL;
-const Bitboard Rank8BB = 0xFF00000000000000ULL;
+inline Bitboard square_bb(Square s) {
+ assert(is_ok(s));
+ return SquareBB[s];
+}
-extern const Bitboard RankBB[8];
-extern const Bitboard RelativeRankBB[2][8];
-extern const Bitboard InFrontBB[2][8];
-extern Bitboard SetMaskBB[65];
-extern Bitboard ClearMaskBB[65];
+/// 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.
-extern Bitboard StepAttackBB[16][64];
-extern Bitboard RayBB[64][8];
-extern Bitboard BetweenBB[64][64];
+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); }
-extern Bitboard PassedPawnMask[2][64];
-extern Bitboard OutpostMask[2][64];
+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; }
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-extern Bitboard RankAttacks[8][64], FileAttacks[8][64];
-#else
-extern const uint64_t RMult[64];
-extern const int RShift[64];
-extern Bitboard RMask[64];
-extern int RAttackIndex[64];
-extern Bitboard RAttacks[0x19000];
-#endif // defined(USE_COMPACT_ROOK_ATTACKS)
+inline Bitboard operator|(Square s1, Square s2) { return square_bb(s1) | s2; }
-extern const uint64_t BMult[64];
-extern const int BShift[64];
-extern Bitboard BMask[64];
-extern int BAttackIndex[64];
-extern Bitboard BAttacks[0x1480];
+constexpr bool more_than_one(Bitboard b) {
+ return b & (b - 1);
+}
-extern Bitboard BishopPseudoAttacks[64];
-extern Bitboard RookPseudoAttacks[64];
-extern Bitboard QueenPseudoAttacks[64];
+constexpr bool opposite_colors(Square s1, Square s2) {
+ return (s1 + rank_of(s1) + s2 + rank_of(s2)) & 1;
+}
-////
-//// Inline functions
-////
+/// rank_bb() and file_bb() return a bitboard representing all the squares on
+/// the given file or rank.
-/// Functions for testing whether a given bit is set in a bitboard, and for
-/// setting and clearing bits.
+constexpr Bitboard rank_bb(Rank r) {
+ return Rank1BB << (8 * r);
+}
-inline Bitboard bit_is_set(Bitboard b, Square s) {
- return b & SetMaskBB[s];
+constexpr Bitboard rank_bb(Square s) {
+ return rank_bb(rank_of(s));
}
-inline void set_bit(Bitboard *b, Square s) {
- *b |= SetMaskBB[s];
+constexpr Bitboard file_bb(File f) {
+ return FileABB << f;
}
-inline void clear_bit(Bitboard *b, Square s) {
- *b &= ClearMaskBB[s];
+constexpr Bitboard file_bb(Square s) {
+ return file_bb(file_of(s));
}
-/// rank_bb() and file_bb() gives a bitboard containing all squares on a given
-/// file or rank. It is also possible to pass a square as input to these
-/// functions.
+/// shift() moves a bitboard one or two steps as specified by the direction D
-inline Bitboard rank_bb(Rank r) {
- return RankBB[r];
+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;
}
-inline Bitboard rank_bb(Square s) {
- return rank_bb(square_rank(s));
-}
-inline Bitboard file_bb(File f) {
- return FileBB[f];
-}
+/// pawn_attacks_bb() returns the squares attacked by pawns of the given color
+/// from the squares in the given bitboard.
-inline Bitboard file_bb(Square s) {
- return file_bb(square_file(s));
+template
+constexpr Bitboard pawn_attacks_bb(Bitboard b) {
+ return C == WHITE ? shift(b) | shift(b)
+ : shift(b) | shift(b);
}
+inline Bitboard pawn_attacks_bb(Color c, Square s) {
-/// neighboring_files_bb takes a file or a square as input, and returns a
-/// bitboard representing all squares on the neighboring files.
-
-inline Bitboard neighboring_files_bb(File f) {
- return NeighboringFilesBB[f];
+ assert(is_ok(s));
+ return PawnAttacks[c][s];
}
-inline Bitboard neighboring_files_bb(Square s) {
- return neighboring_files_bb(square_file(s));
+
+/// pawn_double_attacks_bb() returns the squares doubly attacked by pawns of the
+/// given color from the squares in the given bitboard.
+
+template
+constexpr Bitboard pawn_double_attacks_bb(Bitboard b) {
+ return C == WHITE ? shift(b) & shift(b)
+ : shift(b) & shift(b);
}
-/// 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.
+/// adjacent_files_bb() returns a bitboard representing all the squares on the
+/// adjacent files of a given square.
-inline Bitboard this_and_neighboring_files_bb(File f) {
- return ThisAndNeighboringFilesBB[f];
+constexpr Bitboard adjacent_files_bb(Square s) {
+ return shift(file_bb(s)) | shift(file_bb(s));
}
-inline Bitboard this_and_neighboring_files_bb(Square s) {
- return this_and_neighboring_files_bb(square_file(s));
-}
+/// line_bb() 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.
-/// relative_rank_bb() takes a color and a rank as input, and returns a bitboard
-/// representing all squares on the given rank from the given color's point of
-/// view. For instance, relative_rank_bb(WHITE, 7) gives all squares on the
-/// 7th rank, while relative_rank_bb(BLACK, 7) gives all squares on the 2nd
-/// rank.
+inline Bitboard line_bb(Square s1, Square s2) {
-inline Bitboard relative_rank_bb(Color c, Rank r) {
- return RelativeRankBB[c][r];
+ assert(is_ok(s1) && is_ok(s2));
+ return LineBB[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.
+/// between_bb() returns a bitboard representing squares that are linearly
+/// between the two given squares (excluding the given squares). If the given
+/// squares are not on a same file/rank/diagonal, we return 0. For instance,
+/// between_bb(SQ_C4, SQ_F7) will return a bitboard with squares D5 and E6.
-inline Bitboard in_front_bb(Color c, Rank r) {
- return InFrontBB[c][r];
+inline Bitboard between_bb(Square s1, Square s2) {
+ Bitboard b = line_bb(s1, s2) & ((AllSquares << s1) ^ (AllSquares << s2));
+ return b & (b - 1); //exclude lsb
}
-inline Bitboard in_front_bb(Color c, Square s) {
- return in_front_bb(c, square_rank(s));
+
+/// forward_ranks_bb() returns a bitboard representing the squares on 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.
+
+constexpr Bitboard forward_ranks_bb(Color c, Square s) {
+ return c == WHITE ? ~Rank1BB << 8 * relative_rank(WHITE, s)
+ : ~Rank8BB >> 8 * relative_rank(BLACK, s);
}
-/// behind_bb() takes a color and a rank or square as input, and returns a
-/// bitboard representing all the squares on all ranks behind of the rank
-/// (or square), from the given color's point of view.
+/// 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.
-inline Bitboard behind_bb(Color c, Rank r) {
- return InFrontBB[opposite_color(c)][r];
+constexpr Bitboard forward_file_bb(Color c, Square s) {
+ return forward_ranks_bb(c, s) & file_bb(s);
}
-inline Bitboard behind_bb(Color c, Square s) {
- return in_front_bb(opposite_color(c), square_rank(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.
+
+constexpr Bitboard pawn_attack_span(Color c, Square s) {
+ return forward_ranks_bb(c, s) & adjacent_files_bb(s);
}
-/// ray_bb() gives a bitboard representing all squares along the ray in a
-/// given direction from a given square.
+/// passed_pawn_span() returns a bitboard which can be used to test if a pawn of
+/// the given color and on the given square is a passed pawn.
-inline Bitboard ray_bb(Square s, SignedDirection d) {
- return RayBB[s][d];
+constexpr Bitboard passed_pawn_span(Color c, Square s) {
+ return pawn_attack_span(c, s) | forward_file_bb(c, 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.
+/// aligned() returns true if the squares s1, s2 and s3 are aligned either on a
+/// straight or on a diagonal line.
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-
-inline Bitboard file_attacks_bb(Square s, Bitboard blockers) {
- Bitboard b = (blockers >> square_file(s)) & 0x01010101010100ULL;
- return
- FileAttacks[square_rank(s)][(b*0xd6e8802041d0c441ULL)>>58] & file_bb(s);
+inline bool aligned(Square s1, Square s2, Square s3) {
+ return line_bb(s1, s2) & s3;
}
-inline Bitboard rank_attacks_bb(Square s, Bitboard blockers) {
- Bitboard b = (blockers >> ((s & 56) + 1)) & 63;
- return RankAttacks[square_file(s)][b] & rank_bb(s);
-}
-inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
- return file_attacks_bb(s, blockers) | rank_attacks_bb(s, blockers);
-}
+/// distance() functions return the distance between x and y, defined as the
+/// number of steps for a king in x to reach y.
-#elif defined(USE_32BIT_ATTACKS)
+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)); }
+template<> inline int distance(Square x, Square y) { return std::abs(rank_of(x) - rank_of(y)); }
+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)); }
+inline int edge_distance(Rank r) { return std::min(r, Rank(RANK_8 - r)); }
-inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
- Bitboard b = blockers & RMask[s];
- return RAttacks[RAttackIndex[s] +
- (unsigned(int(b) * int(RMult[s]) ^
- int(b >> 32) * int(RMult[s] >> 32))
- >> RShift[s])];
-}
-#else
+/// safe_destination() returns the bitboard of target square for the given step
+/// from the given square. If the step is off the board, returns empty bitboard.
-inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
- Bitboard b = blockers & RMask[s];
- return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
+inline Bitboard safe_destination(Square s, int step)
+{
+ Square to = Square(s + step);
+ return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0);
}
-#endif
-#if defined(USE_32BIT_ATTACKS)
+/// attacks_bb(Square) returns the pseudo attacks of the give piece type
+/// assuming an empty board.
-inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
- Bitboard b = blockers & BMask[s];
- return BAttacks[BAttackIndex[s] +
- (unsigned(int(b) * int(BMult[s]) ^
- int(b >> 32) * int(BMult[s] >> 32))
- >> BShift[s])];
-}
+template
+inline Bitboard attacks_bb(Square s) {
-#else // defined(USE_32BIT_ATTACKS)
+ assert((Pt != PAWN) && (is_ok(s)));
-inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
- Bitboard b = blockers & BMask[s];
- return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
+ return PseudoAttacks[Pt][s];
}
-#endif // defined(USE_32BIT_ATTACKS)
-inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
- return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
-}
+/// attacks_bb(Square, Bitboard) 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) {
-/// 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.
+ assert((Pt != PAWN) && (is_ok(s)));
-inline Bitboard squares_between(Square s1, Square s2) {
- return BetweenBB[s1][s2];
+ 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 attacks_bb(PieceType pt, Square s, Bitboard occupied) {
-/// 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. For instance,
-/// squares_in_front_of(BLACK, SQ_E4) returns a bitboard with the squares
-/// e3, e2 and e1 set.
+ assert((pt != PAWN) && (is_ok(s)));
-inline Bitboard squares_in_front_of(Color c, Square s) {
- return in_front_bb(c, s) & file_bb(s);
+ switch (pt)
+ {
+ case BISHOP: return attacks_bb(s, occupied);
+ case ROOK : return attacks_bb< ROOK>(s, occupied);
+ case QUEEN : return attacks_bb(s, occupied) | attacks_bb(s, occupied);
+ default : return PseudoAttacks[pt][s];
+ }
}
-/// squares_behind is similar to squares_in_front, but returns the squares
-/// behind the square instead of in front of the square.
+/// popcount() counts the number of non-zero bits in a bitboard
-inline Bitboard squares_behind(Color c, Square s) {
- return in_front_bb(opposite_color(c), s) & file_bb(s);
-}
+inline int popcount(Bitboard b) {
+#ifndef USE_POPCNT
-/// 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.
+ 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 Bitboard passed_pawn_mask(Color c, Square s) {
- return PassedPawnMask[c][s];
-}
+#elif defined(_MSC_VER) || defined(__INTEL_COMPILER)
+
+ return (int)_mm_popcnt_u64(b);
+#else // Assumed gcc or compatible compiler
-/// outpost_mask takes a color and a square as input, and returns a bitboard
-/// mask which can be used to test whether a piece on the square can possibly
-/// be driven away by an enemy pawn.
+ return __builtin_popcountll(b);
-inline Bitboard outpost_mask(Color c, Square s) {
- return OutpostMask[c][s];
+#endif
}
-/// isolated_pawn_mask takes a square as input, and returns a bitboard mask
-/// which can be used to test whether a pawn on the given square is isolated.
+/// lsb() and msb() return the least/most significant bit in a non-zero bitboard
-inline Bitboard isolated_pawn_mask(Square s) {
- return neighboring_files_bb(s);
+#if defined(__GNUC__) // GCC, Clang, ICC
+
+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));
+}
-/// count_1s() counts the number of nonzero bits in a bitboard.
+#elif defined(_MSC_VER) // MSVC
-#if defined(BITCOUNT_LOOP)
+#ifdef _WIN64 // MSVC, WIN64
-inline int count_1s(Bitboard b) {
- int r;
- for(r = 0; b; r++, b &= b - 1);
- return r;
+inline Square lsb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
+ _BitScanForward64(&idx, b);
+ return (Square) idx;
}
-inline int count_1s_max_15(Bitboard b) {
- return count_1s(b);
+inline Square msb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
+ _BitScanReverse64(&idx, b);
+ return (Square) idx;
}
-#elif defined(BITCOUNT_SWAR_32)
+#else // MSVC, WIN32
-inline int count_1s(Bitboard b) {
- unsigned w = unsigned(b >> 32), v = unsigned(b);
- v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
- w -= (w >> 1) & 0x55555555;
- v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
- w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
- v = ((v >> 4) + v) & 0x0F0F0F0F; // 0-8 in 8 bits
- v += (((w >> 4) + w) & 0x0F0F0F0F); // 0-16 in 8 bits
- v *= 0x01010101; // mul is fast on amd procs
- return int(v >> 24);
-}
+inline Square lsb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
-inline int count_1s_max_15(Bitboard b) {
- unsigned w = unsigned(b >> 32), v = unsigned(b);
- v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
- w -= (w >> 1) & 0x55555555;
- v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
- w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
- v += w; // 0-8 in 4 bits
- v *= 0x11111111;
- return int(v >> 28);
+ if (b & 0xffffffff) {
+ _BitScanForward(&idx, int32_t(b));
+ return Square(idx);
+ } else {
+ _BitScanForward(&idx, int32_t(b >> 32));
+ return Square(idx + 32);
+ }
}
-#elif defined(BITCOUNT_SWAR_64)
+inline Square msb(Bitboard b) {
+ assert(b);
+ unsigned long idx;
-inline int count_1s(Bitboard b) {
- b -= ((b>>1) & 0x5555555555555555ULL);
- b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
- b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
- b *= 0x0101010101010101ULL;
- return int(b >> 56);
+ if (b >> 32) {
+ _BitScanReverse(&idx, int32_t(b >> 32));
+ return Square(idx + 32);
+ } else {
+ _BitScanReverse(&idx, int32_t(b));
+ return Square(idx);
+ }
}
-inline int count_1s_max_15(Bitboard b) {
- b -= (b>>1) & 0x5555555555555555ULL;
- b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
- b *= 0x1111111111111111ULL;
- return int(b >> 60);
-}
+#endif
-#endif // BITCOUNT
+#else // Compiler is neither GCC nor MSVC compatible
+#error "Compiler not supported."
-////
-//// Prototypes
-////
+#endif
-extern void print_bitboard(Bitboard b);
-extern void init_bitboards();
-extern Square first_1(Bitboard b);
-extern Square pop_1st_bit(Bitboard *b);
+/// pop_lsb() 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;
+}
+
+
+/// frontmost_sq() returns the most advanced square for the given color,
+/// requires a non-zero bitboard.
+inline Square frontmost_sq(Color c, Bitboard b) {
+ assert(b);
+ return c == WHITE ? msb(b) : lsb(b);
+}
-#endif // !defined(BITBOARD_H_INCLUDED)
+#endif // #ifndef BITBOARD_H_INCLUDED