X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.h;h=2b9161250f5fb8277ba4f2deac1e012646cec331;hp=d5c16a919006f75caf3ddd44ae0c406c3a5440dc;hb=a8e903c33a676decfcf5c721b6b4bfdb4102e5c0;hpb=a87ea9846d4adc8d2ed8107c072c43b5ef53e4fe diff --git a/src/bitboard.h b/src/bitboard.h index d5c16a91..f1db634f 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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 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 @@ -18,195 +18,137 @@ along with this program. If not, see . */ - -#if !defined(BITBOARD_H_INCLUDED) +#ifndef BITBOARD_H_INCLUDED #define BITBOARD_H_INCLUDED -//// -//// Defines -//// +#include -// Quiet a warning on Intel compiler -#if !defined(__SIZEOF_INT__ ) -#define __SIZEOF_INT__ 0 -#endif - -// Check for 64 bits for different compilers: Intel, MSVC and gcc -#if defined(__x86_64) || defined(_WIN64) || (__SIZEOF_INT__ > 4) -#define IS_64BIT -#endif - -#if defined(IS_64BIT) && (defined(__GNUC__) || defined(__INTEL_COMPILER)) -#define USE_BSFQ -#endif +#include "types.h" +namespace Bitbases { -//// -//// Includes -//// +void init(); +bool probe(Square wksq, Square wpsq, Square bksq, Color us); -#include "direction.h" -#include "piece.h" -#include "square.h" -#include "types.h" +} +namespace Bitboards { -//// -//// Types -//// +void init(); +const std::string pretty(Bitboard b); -typedef uint64_t Bitboard; +} +constexpr Bitboard AllSquares = ~Bitboard(0); +constexpr Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL; -//// -//// Constants and variables -//// +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; -const Bitboard EmptyBoardBB = 0ULL; +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); -const Bitboard WhiteSquaresBB = 0x55AA55AA55AA55AAULL; -const Bitboard BlackSquaresBB = 0xAA55AA55AA55AA55ULL; -const Bitboard SquaresByColorBB[2] = { BlackSquaresBB, WhiteSquaresBB }; +extern int SquareDistance[SQUARE_NB][SQUARE_NB]; -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; +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]; -const Bitboard FileBB[8] = { - FileABB, FileBBB, FileCBB, FileDBB, FileEBB, FileFBB, FileGBB, FileHBB -}; -const Bitboard NeighboringFilesBB[8] = { - FileBBB, FileABB|FileCBB, FileBBB|FileDBB, FileCBB|FileEBB, - FileDBB|FileFBB, FileEBB|FileGBB, FileFBB|FileHBB, FileGBB -}; +/// Magic holds all magic bitboards relevant data for a single square +struct Magic { + Bitboard mask; + Bitboard magic; + Bitboard* attacks; + unsigned shift; -const Bitboard ThisAndNeighboringFilesBB[8] = { - FileABB|FileBBB, FileABB|FileBBB|FileCBB, - FileBBB|FileCBB|FileDBB, FileCBB|FileDBB|FileEBB, - FileDBB|FileEBB|FileFBB, FileEBB|FileFBB|FileGBB, - FileFBB|FileGBB|FileHBB, FileGBB|FileHBB -}; + // Compute the attack's index using the 'magic bitboards' approach + unsigned index(Bitboard occupied) const { -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; - -const Bitboard RankBB[8] = { - Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB -}; + if (HasPext) + return unsigned(pext(occupied, mask)); -const Bitboard RelativeRankBB[2][8] = { - { Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB }, - { Rank8BB, Rank7BB, Rank6BB, Rank5BB, Rank4BB, Rank3BB, Rank2BB, Rank1BB } -}; + if (Is64Bit) + return unsigned(((occupied & mask) * magic) >> shift); -const Bitboard InFrontBB[2][8] = { - { Rank2BB | Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB, - Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB, - Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB, - Rank5BB | Rank6BB | Rank7BB | Rank8BB, - Rank6BB | Rank7BB | Rank8BB, - Rank7BB | Rank8BB, - Rank8BB, - EmptyBoardBB - }, - { EmptyBoardBB, - Rank1BB, - Rank2BB | Rank1BB, - Rank3BB | Rank2BB | Rank1BB, - Rank4BB | Rank3BB | Rank2BB | Rank1BB, - Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB, - Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB, - Rank7BB | Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB + unsigned lo = unsigned(occupied) & unsigned(mask); + unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32); + return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift; } }; -const int BitTable[64] = { - 63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2, - 51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5, 52, - 26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38, 28, - 58, 20, 37, 17, 36, 8 -}; +extern Magic RookMagics[SQUARE_NB]; +extern Magic BishopMagics[SQUARE_NB]; -extern Bitboard SetMaskBB[65]; -extern Bitboard ClearMaskBB[65]; -extern Bitboard StepAttackBB[16][64]; -extern Bitboard RayBB[64][8]; -extern Bitboard BetweenBB[64][64]; +/// 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 PassedPawnMask[2][64]; -extern Bitboard OutpostMask[2][64]; - -extern const uint64_t RMult[64]; -extern const int RShift[64]; -extern Bitboard RMask[64]; -extern int RAttackIndex[64]; -extern Bitboard RAttacks[0x19000]; - -extern const uint64_t BMult[64]; -extern const int BShift[64]; -extern Bitboard BMask[64]; -extern int BAttackIndex[64]; -extern Bitboard BAttacks[0x1480]; - -extern Bitboard BishopPseudoAttacks[64]; -extern Bitboard RookPseudoAttacks[64]; -extern Bitboard QueenPseudoAttacks[64]; - - -//// -//// Inline functions -//// - -/// 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 & SetMaskBB[s]; +inline Bitboard operator&(Bitboard b, Square s) { + assert(s >= SQ_A1 && s <= SQ_H8); + return b & SquareBB[s]; } -inline void set_bit(Bitboard *b, Square s) { - *b |= SetMaskBB[s]; +inline Bitboard operator|(Bitboard b, Square s) { + assert(s >= SQ_A1 && s <= SQ_H8); + return b | SquareBB[s]; } -inline void clear_bit(Bitboard *b, Square s) { - *b &= ClearMaskBB[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]; +} -/// 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) { + assert(s >= SQ_A1 && s <= SQ_H8); + return b ^= SquareBB[s]; +} -inline Bitboard make_move_bb(Square from, Square to) { - return SetMaskBB[from] | SetMaskBB[to]; +constexpr bool more_than_one(Bitboard b) { + return b & (b - 1); } -inline void do_move_bb(Bitboard *b, Bitboard move_bb) { - *b ^= move_bb; +inline bool opposite_colors(Square s1, Square s2) { + + return bool(DarkSquares & s1) != bool(DarkSquares & s2); } -/// 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. +/// 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]; } inline Bitboard rank_bb(Square s) { - return rank_bb(square_rank(s)); + return RankBB[rank_of(s)]; } inline Bitboard file_bb(File f) { @@ -214,216 +156,244 @@ inline Bitboard file_bb(File f) { } inline Bitboard file_bb(Square s) { - return file_bb(square_file(s)); + return FileBB[file_of(s)]; } -/// neighboring_files_bb takes a file or a square as input, and returns a -/// bitboard representing all squares on the neighboring files. +/// shift() moves a bitboard one step along direction D (mainly for pawns) -inline Bitboard neighboring_files_bb(File f) { - return NeighboringFilesBB[f]; +template +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; } -inline Bitboard neighboring_files_bb(Square s) { - return neighboring_files_bb(square_file(s)); + +/// pawn_attacks_bb() returns the pawn attacks for 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); } -/// 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. +/// double_pawn_attacks_bb() returns the pawn attacks for the given color +/// from the squares in the given bitboard. -inline Bitboard this_and_neighboring_files_bb(File f) { - return ThisAndNeighboringFilesBB[f]; +template +constexpr Bitboard double_pawn_attacks_bb(Bitboard b) { + return C == WHITE ? shift(b) & shift(b) + : shift(b) & shift(b); } -inline Bitboard this_and_neighboring_files_bb(Square s) { - return this_and_neighboring_files_bb(square_file(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]; } -/// 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. +/// 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 relative_rank_bb(Color c, Rank r) { - return RelativeRankBB[c][r]; +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 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 in_front_bb(c, square_rank(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) + +inline Bitboard forward_file_bb(Color c, Square s) { + return ForwardFileBB[c][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. +/// 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 behind_bb(Color c, Rank r) { - return InFrontBB[opposite_color(c)][r]; +inline Bitboard pawn_attack_span(Color c, Square s) { + return PawnAttackSpan[c][s]; } -inline Bitboard behind_bb(Color c, Square s) { - return in_front_bb(opposite_color(c), square_rank(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) + +inline Bitboard passed_pawn_mask(Color c, Square s) { + return PassedPawnMask[c][s]; } -/// ray_bb() gives a bitboard representing all squares along the ray in a -/// given direction from a given square. +/// aligned() returns true if the squares s1, s2 and s3 are aligned either on a +/// straight or on a diagonal line. -inline Bitboard ray_bb(Square s, SignedDirection d) { - return RayBB[s][d]; +inline bool aligned(Square s1, Square s2, Square s3) { + return LineBB[s1][s2] & s3; } -/// 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. +/// 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. -#if defined(IS_64BIT) +template inline int distance(T x, T y) { return x < y ? y - x : x - y; } +template<> inline int distance(Square x, Square y) { return SquareDistance[x][y]; } -inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) { - Bitboard b = blockers & RMask[s]; - return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])]; -} +template inline int distance(T2 x, T2 y); +template<> inline int distance(Square x, Square y) { return distance(file_of(x), file_of(y)); } +template<> inline int distance(Square x, Square y) { return distance(rank_of(x), rank_of(y)); } -inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) { - Bitboard b = blockers & BMask[s]; - return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])]; -} -#else // if !defined(IS_64BIT) +/// attacks_bb() returns a bitboard representing all the squares attacked by a +/// piece of type Pt (bishop or rook) placed on 's'. -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])]; -} +template +inline Bitboard attacks_bb(Square s, Bitboard occupied) { -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])]; + const Magic& m = Pt == ROOK ? RookMagics[s] : BishopMagics[s]; + return m.attacks[m.index(occupied)]; } -#endif +inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) { + + assert(pt != PAWN); -inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) { - return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers); + 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_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. +/// popcount() counts the number of non-zero bits in a bitboard -inline Bitboard squares_between(Square s1, Square s2) { - return BetweenBB[s1][s2]; -} +inline int popcount(Bitboard b) { +#ifndef USE_POPCNT -/// 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. + 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 Bitboard squares_in_front_of(Color c, Square s) { - return in_front_bb(c, s) & file_bb(s); -} +#elif defined(_MSC_VER) || defined(__INTEL_COMPILER) + return (int)_mm_popcnt_u64(b); -/// squares_behind is similar to squares_in_front, but returns the squares -/// behind the square instead of in front of the square. +#else // Assumed gcc or compatible compiler -inline Bitboard squares_behind(Color c, Square s) { - return in_front_bb(opposite_color(c), s) & file_bb(s); -} + return __builtin_popcountll(b); +#endif +} -/// 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. -inline Bitboard passed_pawn_mask(Color c, Square s) { - return PassedPawnMask[c][s]; -} +/// lsb() and msb() return the least/most significant bit in a non-zero bitboard +#if defined(__GNUC__) // GCC, Clang, ICC -/// 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. +inline Square lsb(Bitboard b) { + assert(b); + return Square(__builtin_ctzll(b)); +} -inline Bitboard outpost_mask(Color c, Square s) { - return OutpostMask[c][s]; +inline Square msb(Bitboard b) { + assert(b); + return Square(63 ^ __builtin_clzll(b)); } +#elif defined(_MSC_VER) // MSVC -/// 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. +#ifdef _WIN64 // MSVC, WIN64 -inline Bitboard isolated_pawn_mask(Square s) { - return neighboring_files_bb(s); +inline Square lsb(Bitboard b) { + assert(b); + unsigned long idx; + _BitScanForward64(&idx, b); + return (Square) idx; } +inline Square msb(Bitboard b) { + assert(b); + unsigned long idx; + _BitScanReverse64(&idx, b); + return (Square) idx; +} -/// 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. +#else // MSVC, WIN32 -#if defined(USE_BSFQ) // Assembly code by Heinz van Saanen +inline Square lsb(Bitboard b) { + assert(b); + unsigned long idx; -inline Square __attribute__((always_inline)) first_1(Bitboard b) { - Bitboard dummy; - __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) ); - return (Square)(dummy); + if (b & 0xffffffff) { + _BitScanForward(&idx, int32_t(b)); + return Square(idx); + } else { + _BitScanForward(&idx, int32_t(b >> 32)); + return Square(idx + 32); + } } -inline Square __attribute__((always_inline)) pop_1st_bit(Bitboard* b) { - const Square s = first_1(*b); - *b &= ~(1ULL<> 32) { + _BitScanReverse(&idx, int32_t(b >> 32)); + return Square(idx + 32); + } else { + _BitScanReverse(&idx, int32_t(b)); + return Square(idx); + } } -#else // if !defined(USE_BSFQ) +#endif -inline Square first_1(Bitboard b) { - b ^= (b - 1); - uint32_t fold = int(b) ^ int(b >> 32); - return Square(BitTable[(fold * 0x783a9b23) >> 26]); -} +#else // Compiler is neither GCC nor MSVC compatible -extern Square pop_1st_bit(Bitboard* b); +#error "Compiler not supported." #endif -//// -//// Prototypes -//// +/// 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; +} + -extern void print_bitboard(Bitboard b); -extern void init_bitboards(); +/// 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