X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.h;h=3afbeedfbab42ee086000de51a4964350b34bea5;hp=847132c499fdc41df9cddf97e44f01c90dd4bb7f;hb=49e110c52b19f5c99954d4797b8e991b0b60007c;hpb=389dc0e83bd0a205952432fc9e866dbe32bd54e1 diff --git a/src/bitboard.h b/src/bitboard.h index 847132c4..3afbeedf 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -1,7 +1,7 @@ /* 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) 2008-2013 Marco Costalba, Joona Kiiski, 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 @@ -18,431 +18,311 @@ along with this program. If not, see . */ - -#if !defined(BITBOARD_H_INCLUDED) +#ifndef BITBOARD_H_INCLUDED #define BITBOARD_H_INCLUDED - -//// -//// Defines -//// - -// Comment following define if you prefer manually adjust -// platform macros defined below -#define AUTO_CONFIGURATION - -// 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(AUTO_CONFIGURATION) || defined(IS_64BIT) - -//#define USE_COMPACT_ROOK_ATTACKS -//#define USE_32BIT_ATTACKS -#define USE_FOLDED_BITSCAN - -#define BITCOUNT_SWAR_64 -//#define BITCOUNT_SWAR_32 -//#define BITCOUNT_LOOP - -#else - -#define USE_32BIT_ATTACKS -#define USE_FOLDED_BITSCAN -#define BITCOUNT_SWAR_32 - -#endif - -//// -//// Includes -//// - -#include "direction.h" -#include "piece.h" -#include "square.h" #include "types.h" +namespace Bitboards { -//// -//// Types -//// - -typedef uint64_t Bitboard; +void init(); +void print(Bitboard b); +} -//// -//// Constants and variables -//// - -const Bitboard EmptyBoardBB = 0ULL; +namespace Bitbases { -const Bitboard WhiteSquaresBB = 0x55AA55AA55AA55AAULL; -const Bitboard BlackSquaresBB = 0xAA55AA55AA55AA55ULL; +void init_kpk(); +bool probe_kpk(Square wksq, Square wpsq, Square bksq, Color us); -extern const Bitboard SquaresByColorBB[2]; +} 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 const Bitboard FileBB[8]; -extern const Bitboard NeighboringFilesBB[8]; -extern const Bitboard ThisAndNeighboringFilesBB[8]; - -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; - -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]; +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; -extern Bitboard StepAttackBB[16][64]; -extern Bitboard RayBB[64][8]; -extern Bitboard BetweenBB[64][64]; +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 PassedPawnMask[2][64]; -extern Bitboard OutpostMask[2][64]; +CACHE_LINE_ALIGNMENT -#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) +extern Bitboard RMasks[SQUARE_NB]; +extern Bitboard RMagics[SQUARE_NB]; +extern Bitboard* RAttacks[SQUARE_NB]; +extern unsigned RShifts[SQUARE_NB]; -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 BMasks[SQUARE_NB]; +extern Bitboard BMagics[SQUARE_NB]; +extern Bitboard* BAttacks[SQUARE_NB]; +extern unsigned BShifts[SQUARE_NB]; -extern Bitboard BishopPseudoAttacks[64]; -extern Bitboard RookPseudoAttacks[64]; -extern Bitboard QueenPseudoAttacks[64]; +extern Bitboard SquareBB[SQUARE_NB]; +extern Bitboard FileBB[FILE_NB]; +extern Bitboard RankBB[RANK_NB]; +extern Bitboard AdjacentFilesBB[FILE_NB]; +extern Bitboard InFrontBB[COLOR_NB][RANK_NB]; +extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB]; +extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB]; +extern Bitboard DistanceRingsBB[SQUARE_NB][8]; +extern Bitboard ForwardBB[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 int SquareDistance[SQUARE_NB][SQUARE_NB]; -//// -//// Inline functions -//// +const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL; -/// Functions for testing whether a given bit is set in a bitboard, and for -/// setting and clearing bits. +/// 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 bit_is_set(Bitboard b, Square s) { - return b & SetMaskBB[s]; +inline Bitboard operator&(Bitboard b, Square s) { + return b & SquareBB[s]; } -inline void set_bit(Bitboard *b, Square s) { - *b |= SetMaskBB[s]; +inline Bitboard& operator|=(Bitboard& b, Square s) { + return b |= SquareBB[s]; } -inline void clear_bit(Bitboard *b, Square s) { - *b &= ClearMaskBB[s]; +inline Bitboard& operator^=(Bitboard& b, Square s) { + return b ^= SquareBB[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. - -inline Bitboard rank_bb(Rank r) { - return RankBB[r]; +inline Bitboard operator|(Bitboard b, Square s) { + return b | SquareBB[s]; } -inline Bitboard rank_bb(Square s) { - return rank_bb(square_rank(s)); +inline Bitboard operator^(Bitboard b, Square s) { + return b ^ SquareBB[s]; } -inline Bitboard file_bb(File f) { - return FileBB[f]; +inline bool more_than_one(Bitboard b) { + return b & (b - 1); } -inline Bitboard file_bb(Square s) { - return file_bb(square_file(s)); +inline int square_distance(Square s1, Square s2) { + return SquareDistance[s1][s2]; } - -/// 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]; +inline int file_distance(Square s1, Square s2) { + return abs(file_of(s1) - file_of(s2)); } -inline Bitboard neighboring_files_bb(Square s) { - return neighboring_files_bb(square_file(s)); -} - - -/// 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]; +inline int rank_distance(Square s1, Square s2) { + return abs(rank_of(s1) - rank_of(s2)); } -inline Bitboard this_and_neighboring_files_bb(Square s) { - return this_and_neighboring_files_bb(square_file(s)); -} +/// shift_bb() moves bitboard one step along direction Delta. Mainly for pawns. -/// 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. +template +inline Bitboard shift_bb(Bitboard b) { -inline Bitboard relative_rank_bb(Color c, Rank r) { - return RelativeRankBB[c][r]; + return Delta == DELTA_N ? b << 8 : Delta == DELTA_S ? b >> 8 + : Delta == DELTA_NE ? (b & ~FileHBB) << 9 : Delta == DELTA_SE ? (b & ~FileHBB) >> 7 + : Delta == DELTA_NW ? (b & ~FileABB) << 7 : Delta == DELTA_SW ? (b & ~FileABB) >> 9 + : 0; } -/// 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. +/// 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. -inline Bitboard in_front_bb(Color c, Rank r) { - return InFrontBB[c][r]; +inline Bitboard rank_bb(Rank r) { + return RankBB[r]; } -inline Bitboard in_front_bb(Color c, Square s) { - return in_front_bb(c, square_rank(s)); +inline Bitboard rank_bb(Square s) { + return RankBB[rank_of(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. - -inline Bitboard behind_bb(Color c, Rank r) { - return InFrontBB[opposite_color(c)][r]; +inline Bitboard file_bb(File f) { + return FileBB[f]; } -inline Bitboard behind_bb(Color c, Square s) { - return in_front_bb(opposite_color(c), square_rank(s)); +inline Bitboard file_bb(Square s) { + return FileBB[file_of(s)]; } -/// ray_bb() gives a bitboard representing all squares along the ray in a -/// given direction from a given square. +/// adjacent_files_bb() takes a file as input and returns a bitboard representing +/// all squares on the adjacent files. -inline Bitboard ray_bb(Square s, SignedDirection d) { - return RayBB[s][d]; +inline Bitboard adjacent_files_bb(File f) { + return AdjacentFilesBB[f]; } -/// 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. - -#if defined(USE_COMPACT_ROOK_ATTACKS) +/// in_front_bb() takes a color and a rank as input, and returns a bitboard +/// representing all the squares on all ranks in front of the rank, from the +/// given color's point of view. For instance, in_front_bb(BLACK, RANK_3) will +/// give all squares on ranks 1 and 2. -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 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 in_front_bb(Color c, Rank r) { + return InFrontBB[c][r]; } -inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) { - return file_attacks_bb(s, blockers) | rank_attacks_bb(s, blockers); -} -#elif defined(USE_32BIT_ATTACKS) +/// between_bb() returns a bitboard representing all squares between two squares. +/// 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 line, file or diagonal, +/// 0 is returned. -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])]; +inline Bitboard between_bb(Square s1, Square s2) { + return BetweenBB[s1][s2]; } -#else -inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) { - Bitboard b = blockers & RMask[s]; - return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])]; +/// forward_bb() 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: +/// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s) + +inline Bitboard forward_bb(Color c, Square s) { + return ForwardBB[c][s]; } -#endif -#if defined(USE_32BIT_ATTACKS) +/// pawn_attack_span() 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: +/// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s); -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])]; +inline Bitboard pawn_attack_span(Color c, Square s) { + return PawnAttackSpan[c][s]; } -#else // defined(USE_32BIT_ATTACKS) - -inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) { - Bitboard b = blockers & BMask[s]; - return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])]; -} -#endif // defined(USE_32BIT_ATTACKS) +/// 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] = pawn_attack_span(c, s) | forward_bb(c, s) -inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) { - return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers); +inline Bitboard passed_pawn_mask(Color c, Square s) { + return PassedPawnMask[c][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. +/// squares_of_color() returns a bitboard representing all squares with the same +/// color of the given square. -inline Bitboard squares_between(Square s1, Square s2) { - return BetweenBB[s1][s2]; +inline Bitboard squares_of_color(Square s) { + return DarkSquares & s ? DarkSquares : ~DarkSquares; } -/// 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. +/// squares_aligned() returns true if the squares s1, s2 and s3 are aligned +/// either on a straight or on a diagonal line. -inline Bitboard squares_in_front_of(Color c, Square s) { - return in_front_bb(c, s) & file_bb(s); +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]); } -/// squares_behind is similar to squares_in_front, but returns the squares -/// behind the square instead of in front of the square. +/// Functions for computing sliding attack bitboards. Function attacks_bb() takes +/// a square and a bitboard of occupied squares as input, and returns a bitboard +/// representing all squares attacked by Pt (bishop or rook) on the given square. +template +FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) { -inline Bitboard squares_behind(Color c, Square s) { - return in_front_bb(opposite_color(c), s) & file_bb(s); -} + Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks; + Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics; + unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts; + if (Is64Bit) + return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[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. - -inline Bitboard passed_pawn_mask(Color c, Square s) { - return PassedPawnMask[c][s]; + unsigned lo = unsigned(occ) & unsigned(Masks[s]); + unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32); + return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s]; } +template +inline Bitboard attacks_bb(Square s, Bitboard occ) { + return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index(s, occ)]; +} -/// 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 Bitboard outpost_mask(Color c, Square s) { - return OutpostMask[c][s]; -} +/// lsb()/msb() finds the least/most significant bit in a nonzero bitboard. +/// pop_lsb() finds and clears the least significant bit in a nonzero bitboard. +#ifdef USE_BSFQ -/// 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. +# if defined(_MSC_VER) && !defined(__INTEL_COMPILER) -inline Bitboard isolated_pawn_mask(Square s) { - return neighboring_files_bb(s); +FORCE_INLINE Square lsb(Bitboard b) { + unsigned long index; + _BitScanForward64(&index, b); + return (Square) index; } +FORCE_INLINE Square msb(Bitboard b) { + unsigned long index; + _BitScanReverse64(&index, b); + return (Square) index; +} -/// count_1s() counts the number of nonzero bits in a bitboard. +# elif defined(__arm__) -#if defined(BITCOUNT_LOOP) +FORCE_INLINE int lsb32(uint32_t v) { + __asm__("rbit %0, %1" : "=r"(v) : "r"(v)); + return __builtin_clz(v); +} -inline int count_1s(Bitboard b) { - int r; - for(r = 0; b; r++, b &= b - 1); - return r; +FORCE_INLINE Square msb(Bitboard b) { + return (Square) (63 - __builtin_clzll(b)); } -inline int count_1s_max_15(Bitboard b) { - return count_1s(b); +FORCE_INLINE Square lsb(Bitboard b) { + return (Square) (uint32_t(b) ? lsb32(uint32_t(b)) : 32 + lsb32(uint32_t(b >> 32))); } -#elif defined(BITCOUNT_SWAR_32) +# else -inline int count_1s(Bitboard b) { - unsigned w = unsigned(b >> 32), v = unsigned(b); - v = v - ((v >> 1) & 0x55555555); - w = w - ((w >> 1) & 0x55555555); - v = (v & 0x33333333) + ((v >> 2) & 0x33333333); - w = (w & 0x33333333) + ((w >> 2) & 0x33333333); - v = (v + (v >> 4)) & 0x0F0F0F0F; - w = (w + (w >> 4)) & 0x0F0F0F0F; - v = ((v+w) * 0x01010101) >> 24; // mul is fast on amd procs - return int(v); +FORCE_INLINE Square lsb(Bitboard b) { // Assembly code by Heinz van Saanen + Bitboard index; + __asm__("bsfq %1, %0": "=r"(index): "rm"(b) ); + return (Square) index; } -inline int count_1s_max_15(Bitboard b) { - unsigned w = unsigned(b >> 32), v = unsigned(b); - v = v - ((v >> 1) & 0x55555555); - w = w - ((w >> 1) & 0x55555555); - v = (v & 0x33333333) + ((v >> 2) & 0x33333333); - w = (w & 0x33333333) + ((w >> 2) & 0x33333333); - v = ((v+w) * 0x11111111) >> 28; - return int(v); +FORCE_INLINE Square msb(Bitboard b) { + Bitboard index; + __asm__("bsrq %1, %0": "=r"(index): "rm"(b) ); + return (Square) index; } -#elif defined(BITCOUNT_SWAR_64) - -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); -} +# endif -inline int count_1s_max_15(Bitboard b) { - b -= (b>>1) & 0x5555555555555555ULL; - b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL); - b *= 0x1111111111111111ULL; - return int(b >> 60); +FORCE_INLINE Square pop_lsb(Bitboard* b) { + const Square s = lsb(*b); + *b &= *b - 1; + return s; } -#endif // BITCOUNT +#else // if defined(USE_BSFQ) +extern Square msb(Bitboard b); +extern Square lsb(Bitboard b); +extern Square pop_lsb(Bitboard* b); -//// -//// 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); +/// frontmost_sq() and backmost_sq() find 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