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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2017 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
extern int SquareDistance[SQUARE_NB][SQUARE_NB];
-extern Bitboard RookMasks [SQUARE_NB];
-extern Bitboard RookMagics [SQUARE_NB];
-extern Bitboard* RookAttacks[SQUARE_NB];
-extern unsigned RookShifts [SQUARE_NB];
-
-extern Bitboard BishopMasks [SQUARE_NB];
-extern Bitboard BishopMagics [SQUARE_NB];
-extern Bitboard* BishopAttacks[SQUARE_NB];
-extern unsigned BishopShifts [SQUARE_NB];
-
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 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 ForwardBB[COLOR_NB][SQUARE_NB];
+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
+struct Magic {
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
+
+ /// looks up the index using the 'magic bitboards' approach.
+ unsigned index(Bitboard occupied) const {
+
+ if (HasPext)
+ return unsigned(pext(occupied, mask));
+
+ 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;
+ }
+};
+
+extern Magic RookMagics[SQUARE_NB];
+extern Magic BishopMagics[SQUARE_NB];
/// Overloads of bitwise operators between a Bitboard and a Square for testing
}
-/// shift_bb() moves a bitboard one step along direction Delta. Mainly for pawns
+/// shift() moves a bitboard one step along direction D. Mainly for pawns
-template<Square Delta>
-inline Bitboard shift_bb(Bitboard b) {
- 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
+template<Square D>
+inline Bitboard shift(Bitboard b) {
+ return D == NORTH ? b << 8 : D == SOUTH ? b >> 8
+ : D == NORTH_EAST ? (b & ~FileHBB) << 9 : D == SOUTH_EAST ? (b & ~FileHBB) >> 7
+ : D == NORTH_WEST ? (b & ~FileABB) << 7 : D == SOUTH_WEST ? (b & ~FileABB) >> 9
: 0;
}
}
-/// in_front_bb() returns a bitboard representing all the squares on all the ranks
+/// forward_ranks_bb() returns a bitboard representing all the squares on all the ranks
/// in front of the given one, from the point of view of the given color. For
-/// instance, in_front_bb(BLACK, RANK_3) will return the squares on ranks 1 and 2.
+/// 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)];
}
-/// forward_bb() returns a bitboard representing all the squares along the line
+/// 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:
-/// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
+/// ForwardFileBB[c][s] = forward_ranks_bb(c, s) & file_bb(s)
-inline Bitboard forward_bb(Color c, Square s) {
- return ForwardBB[c][s];
+inline Bitboard forward_file_bb(Color c, Square s) {
+ return ForwardFileBB[c][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:
-/// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
+/// 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];
/// 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_bb(c, s)
+/// 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];
/// attacks_bb() returns a bitboard representing all the squares attacked by a
-/// piece of type Pt (bishop or rook) placed on 's'. The helper magic_index()
-/// looks up the index using the 'magic bitboards' approach.
-template<PieceType Pt>
-inline unsigned magic_index(Square s, Bitboard occupied) {
-
- Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks;
- Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics;
- unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts;
-
- if (HasPext)
- return unsigned(pext(occupied, Masks[s]));
-
- if (Is64Bit)
- return unsigned(((occupied & Masks[s]) * Magics[s]) >> Shifts[s]);
-
- unsigned lo = unsigned(occupied) & unsigned(Masks[s]);
- unsigned hi = unsigned(occupied >> 32) & unsigned(Masks[s] >> 32);
- return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
-}
+/// piece of type Pt (bishop or rook) placed on 's'.
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
- return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index<Pt>(s, occupied)];
+
+ const Magic& M = Pt == ROOK ? RookMagics[s] : BishopMagics[s];
+ return M.attacks[M.index(occupied)];
}
-inline Bitboard attacks_bb(Piece pc, Square s, Bitboard occupied) {
+inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
+
+ assert(pt != PAWN);
- switch (type_of(pc))
+ switch (pt)
{
case BISHOP: return attacks_bb<BISHOP>(s, occupied);
- case ROOK : return attacks_bb<ROOK>(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 StepAttacksBB[pc][s];
+ default : return PseudoAttacks[pt][s];
}
}
+/// popcount() 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]];
+
+#elif defined(_MSC_VER) || defined(__INTEL_COMPILER)
+
+ return (int)_mm_popcnt_u64(b);
+
+#else // Assumed gcc or compatible compiler
+
+ return __builtin_popcountll(b);
+
+#endif
+}
+
+
/// lsb() and msb() return the least/most significant bit in a non-zero bitboard
#if defined(__GNUC__)
-inline Square lsb(Bitboard b) { return Square(__builtin_ctzll(b)); }
-inline Square msb(Bitboard b) { return Square(63 - __builtin_clzll(b)); }
+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));
+}
#elif defined(_WIN64) && defined(_MSC_VER)
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;
projects / stockfish / blobdiff