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https://github.com/sockspls/badfish
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e56342ed00
Shrinking from [16] to [2][2] is able to speedup perft of start position of almost 5% ! No functional change. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
468 lines
16 KiB
C++
468 lines
16 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <algorithm>
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#include <cassert>
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#include "movegen.h"
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#include "position.h"
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/// Simple macro to wrap a very common while loop, no facny, no flexibility,
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/// hardcoded names 'mlist' and 'from'.
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#define SERIALIZE(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b))
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/// Version used for pawns, where the 'from' square is given as a delta from the 'to' square
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#define SERIALIZE_PAWNS(b, d) while (b) { Square to = pop_1st_bit(&b); \
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(*mlist++).move = make_move(to - (d), to); }
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namespace {
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template<CastlingSide Side, bool OnlyChecks>
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MoveStack* generate_castle(const Position& pos, MoveStack* mlist, Color us) {
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CastleRight cr = CastleRight((Side == KING_SIDE ? WHITE_OO : WHITE_OOO) << us);
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if (pos.castle_impeded(us, Side) || !pos.can_castle(cr))
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return mlist;
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// After castling, the rook and king final positions are the same in Chess960
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// as they would be in standard chess.
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Square kfrom = pos.king_square(us);
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Square kto = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
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Square rfrom = pos.castle_rook_square(us, Side);
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Bitboard enemies = pos.pieces(~us);
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assert(!pos.in_check());
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for (Square s = std::min(kfrom, kto), e = std::max(kfrom, kto); s <= e; s++)
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if ( s != kfrom // We are not in check
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&& (pos.attackers_to(s) & enemies))
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return mlist;
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// Because we generate only legal castling moves we need to verify that
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// when moving the castling rook we do not discover some hidden checker.
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// For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
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if ( pos.is_chess960()
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&& (pos.attackers_to(kto, pos.pieces() ^ rfrom) & enemies))
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return mlist;
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(*mlist++).move = make_castle(kfrom, rfrom);
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if (OnlyChecks && !pos.move_gives_check((mlist - 1)->move, CheckInfo(pos)))
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mlist--;
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return mlist;
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}
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template<Square Delta>
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inline Bitboard move_pawns(Bitboard p) {
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return Delta == DELTA_N ? p << 8
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: Delta == DELTA_S ? p >> 8
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: Delta == DELTA_NE ? (p & ~FileHBB) << 9
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: Delta == DELTA_SE ? (p & ~FileHBB) >> 7
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: Delta == DELTA_NW ? (p & ~FileABB) << 7
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: Delta == DELTA_SW ? (p & ~FileABB) >> 9 : 0;
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}
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template<MoveType Type, Square Delta>
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inline MoveStack* generate_promotions(MoveStack* mlist, Bitboard pawnsOn7, Bitboard target, Square ksq) {
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Bitboard b = move_pawns<Delta>(pawnsOn7) & target;
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while (b)
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{
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Square to = pop_1st_bit(&b);
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if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
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(*mlist++).move = make_promotion(to - Delta, to, QUEEN);
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if (Type == MV_QUIET || Type == MV_EVASION || Type == MV_NON_EVASION)
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{
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(*mlist++).move = make_promotion(to - Delta, to, ROOK);
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(*mlist++).move = make_promotion(to - Delta, to, BISHOP);
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(*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
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}
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// Knight-promotion is the only one that can give a direct check not
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// already included in the queen-promotion.
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if (Type == MV_QUIET_CHECK && (StepAttacksBB[W_KNIGHT][to] & ksq))
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(*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
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else
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(void)ksq; // Silence a warning under MSVC
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}
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return mlist;
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}
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template<Color Us, MoveType Type>
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MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq = SQ_NONE) {
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// Compute our parametrized parameters at compile time, named according to
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// the point of view of white side.
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const Color Them = (Us == WHITE ? BLACK : WHITE);
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const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
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const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
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const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
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const Square UP = (Us == WHITE ? DELTA_N : DELTA_S);
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const Square RIGHT = (Us == WHITE ? DELTA_NE : DELTA_SW);
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const Square LEFT = (Us == WHITE ? DELTA_NW : DELTA_SE);
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Bitboard b1, b2, dc1, dc2, emptySquares;
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Bitboard pawnsOn7 = pos.pieces(PAWN, Us) & TRank7BB;
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Bitboard pawnsNotOn7 = pos.pieces(PAWN, Us) & ~TRank7BB;
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Bitboard enemies = (Type == MV_EVASION ? pos.pieces(Them) & target:
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Type == MV_CAPTURE ? target : pos.pieces(Them));
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// Single and double pawn pushes, no promotions
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if (Type != MV_CAPTURE)
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{
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emptySquares = (Type == MV_QUIET ? target : ~pos.pieces());
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b1 = move_pawns<UP>(pawnsNotOn7) & emptySquares;
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b2 = move_pawns<UP>(b1 & TRank3BB) & emptySquares;
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if (Type == MV_EVASION) // Consider only blocking squares
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{
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b1 &= target;
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b2 &= target;
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}
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if (Type == MV_QUIET_CHECK)
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{
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b1 &= pos.attacks_from<PAWN>(ksq, Them);
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b2 &= pos.attacks_from<PAWN>(ksq, Them);
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// Add pawn pushes which give discovered check. This is possible only
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// if the pawn is not on the same file as the enemy king, because we
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// don't generate captures. Note that a possible discovery check
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// promotion has been already generated among captures.
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if (pawnsNotOn7 & target) // Target is dc bitboard
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{
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dc1 = move_pawns<UP>(pawnsNotOn7 & target) & emptySquares & ~file_bb(ksq);
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dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
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b1 |= dc1;
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b2 |= dc2;
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}
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}
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SERIALIZE_PAWNS(b1, UP);
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SERIALIZE_PAWNS(b2, UP + UP);
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}
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// Promotions and underpromotions
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if (pawnsOn7 && (Type != MV_EVASION || (target & TRank8BB)))
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{
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if (Type == MV_CAPTURE)
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emptySquares = ~pos.pieces();
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if (Type == MV_EVASION)
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emptySquares &= target;
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mlist = generate_promotions<Type, RIGHT>(mlist, pawnsOn7, enemies, ksq);
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mlist = generate_promotions<Type, LEFT>(mlist, pawnsOn7, enemies, ksq);
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mlist = generate_promotions<Type, UP>(mlist, pawnsOn7, emptySquares, ksq);
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}
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// Standard and en-passant captures
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if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
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{
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b1 = move_pawns<RIGHT>(pawnsNotOn7) & enemies;
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b2 = move_pawns<LEFT >(pawnsNotOn7) & enemies;
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SERIALIZE_PAWNS(b1, RIGHT);
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SERIALIZE_PAWNS(b2, LEFT);
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if (pos.ep_square() != SQ_NONE)
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{
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assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6));
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// An en passant capture can be an evasion only if the checking piece
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// is the double pushed pawn and so is in the target. Otherwise this
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// is a discovery check and we are forced to do otherwise.
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if (Type == MV_EVASION && !(target & (pos.ep_square() - UP)))
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return mlist;
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b1 = pawnsNotOn7 & pos.attacks_from<PAWN>(pos.ep_square(), Them);
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assert(b1);
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while (b1)
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(*mlist++).move = make_enpassant(pop_1st_bit(&b1), pos.ep_square());
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}
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}
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return mlist;
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}
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template<PieceType Pt>
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inline MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist,
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Color us, const CheckInfo& ci) {
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assert(Pt != KING && Pt != PAWN);
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Bitboard b, target;
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Square from;
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const Square* pl = pos.piece_list(us, Pt);
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if (*pl != SQ_NONE)
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{
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target = ci.checkSq[Pt] & ~pos.pieces(); // Non capture checks only
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do {
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from = *pl;
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if ( (Pt == BISHOP || Pt == ROOK || Pt == QUEEN)
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&& !(PseudoAttacks[Pt][from] & target))
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continue;
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if (ci.dcCandidates && (ci.dcCandidates & from))
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continue;
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b = pos.attacks_from<Pt>(from) & target;
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SERIALIZE(b);
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} while (*++pl != SQ_NONE);
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}
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return mlist;
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}
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template<PieceType Pt>
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FORCE_INLINE MoveStack* generate_moves(const Position& pos, MoveStack* mlist,
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Color us, Bitboard target) {
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assert(Pt != KING && Pt != PAWN);
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Bitboard b;
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Square from;
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const Square* pl = pos.piece_list(us, Pt);
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if (*pl != SQ_NONE)
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do {
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from = *pl;
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b = pos.attacks_from<Pt>(from) & target;
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SERIALIZE(b);
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} while (*++pl != SQ_NONE);
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return mlist;
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}
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template<>
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FORCE_INLINE MoveStack* generate_moves<KING>(const Position& pos, MoveStack* mlist,
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Color us, Bitboard target) {
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Square from = pos.king_square(us);
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Bitboard b = pos.attacks_from<KING>(from) & target;
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SERIALIZE(b);
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return mlist;
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}
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} // namespace
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/// generate<MV_CAPTURE> generates all pseudo-legal captures and queen
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/// promotions. Returns a pointer to the end of the move list.
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///
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/// generate<MV_QUIET> generates all pseudo-legal non-captures and
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/// underpromotions. Returns a pointer to the end of the move list.
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///
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/// generate<MV_NON_EVASION> generates all pseudo-legal captures and
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/// non-captures. Returns a pointer to the end of the move list.
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template<MoveType Type>
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MoveStack* generate(const Position& pos, MoveStack* mlist) {
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assert(Type == MV_CAPTURE || Type == MV_QUIET || Type == MV_NON_EVASION);
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assert(!pos.in_check());
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Color us = pos.side_to_move();
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Bitboard target;
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if (Type == MV_CAPTURE)
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target = pos.pieces(~us);
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else if (Type == MV_QUIET)
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target = ~pos.pieces();
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else if (Type == MV_NON_EVASION)
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target = ~pos.pieces(us);
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mlist = (us == WHITE ? generate_pawn_moves<WHITE, Type>(pos, mlist, target)
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: generate_pawn_moves<BLACK, Type>(pos, mlist, target));
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mlist = generate_moves<KNIGHT>(pos, mlist, us, target);
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mlist = generate_moves<BISHOP>(pos, mlist, us, target);
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mlist = generate_moves<ROOK>(pos, mlist, us, target);
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mlist = generate_moves<QUEEN>(pos, mlist, us, target);
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mlist = generate_moves<KING>(pos, mlist, us, target);
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if (Type != MV_CAPTURE && pos.can_castle(us))
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{
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mlist = generate_castle<KING_SIDE, false>(pos, mlist, us);
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mlist = generate_castle<QUEEN_SIDE, false>(pos, mlist, us);
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}
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return mlist;
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}
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// Explicit template instantiations
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template MoveStack* generate<MV_CAPTURE>(const Position& pos, MoveStack* mlist);
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template MoveStack* generate<MV_QUIET>(const Position& pos, MoveStack* mlist);
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template MoveStack* generate<MV_NON_EVASION>(const Position& pos, MoveStack* mlist);
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/// generate<MV_QUIET_CHECK> generates all pseudo-legal non-captures and knight
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/// underpromotions that give check. Returns a pointer to the end of the move list.
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template<>
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MoveStack* generate<MV_QUIET_CHECK>(const Position& pos, MoveStack* mlist) {
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assert(!pos.in_check());
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Color us = pos.side_to_move();
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CheckInfo ci(pos);
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Bitboard dc = ci.dcCandidates;
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while (dc)
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{
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Square from = pop_1st_bit(&dc);
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PieceType pt = type_of(pos.piece_on(from));
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if (pt == PAWN)
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continue; // Will be generated togheter with direct checks
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Bitboard b = pos.attacks_from(Piece(pt), from) & ~pos.pieces();
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if (pt == KING)
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b &= ~PseudoAttacks[QUEEN][ci.ksq];
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SERIALIZE(b);
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}
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mlist = (us == WHITE ? generate_pawn_moves<WHITE, MV_QUIET_CHECK>(pos, mlist, ci.dcCandidates, ci.ksq)
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: generate_pawn_moves<BLACK, MV_QUIET_CHECK>(pos, mlist, ci.dcCandidates, ci.ksq));
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mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, ci);
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mlist = generate_direct_checks<BISHOP>(pos, mlist, us, ci);
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mlist = generate_direct_checks<ROOK>(pos, mlist, us, ci);
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mlist = generate_direct_checks<QUEEN>(pos, mlist, us, ci);
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if (pos.can_castle(us))
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{
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mlist = generate_castle<KING_SIDE, true>(pos, mlist, us);
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mlist = generate_castle<QUEEN_SIDE, true>(pos, mlist, us);
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}
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return mlist;
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}
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/// generate<MV_EVASION> generates all pseudo-legal check evasions when the side
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/// to move is in check. Returns a pointer to the end of the move list.
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template<>
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MoveStack* generate<MV_EVASION>(const Position& pos, MoveStack* mlist) {
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assert(pos.in_check());
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Bitboard b, target;
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Square from, checksq;
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int checkersCnt = 0;
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Color us = pos.side_to_move();
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Square ksq = pos.king_square(us);
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Bitboard sliderAttacks = 0;
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Bitboard checkers = pos.checkers();
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assert(checkers);
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// Find squares attacked by slider checkers, we will remove them from the king
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// evasions so to skip known illegal moves avoiding useless legality check later.
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b = checkers;
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do
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{
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checkersCnt++;
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checksq = pop_1st_bit(&b);
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assert(color_of(pos.piece_on(checksq)) == ~us);
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switch (type_of(pos.piece_on(checksq)))
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{
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case BISHOP: sliderAttacks |= PseudoAttacks[BISHOP][checksq]; break;
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case ROOK: sliderAttacks |= PseudoAttacks[ROOK][checksq]; break;
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case QUEEN:
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// If queen and king are far or not on a diagonal line we can safely
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// remove all the squares attacked in the other direction becuase are
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// not reachable by the king anyway.
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if (squares_between(ksq, checksq) || !(PseudoAttacks[BISHOP][checksq] & ksq))
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sliderAttacks |= PseudoAttacks[QUEEN][checksq];
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// Otherwise we need to use real rook attacks to check if king is safe
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// to move in the other direction. For example: king in B2, queen in A1
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// a knight in B1, and we can safely move to C1.
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else
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sliderAttacks |= PseudoAttacks[BISHOP][checksq] | pos.attacks_from<ROOK>(checksq);
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default:
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break;
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}
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} while (b);
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// Generate evasions for king, capture and non capture moves
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b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
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from = ksq;
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SERIALIZE(b);
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// Generate evasions for other pieces only if not under a double check
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if (checkersCnt > 1)
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return mlist;
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// Blocking evasions or captures of the checking piece
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target = squares_between(checksq, ksq) | checkers;
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mlist = (us == WHITE ? generate_pawn_moves<WHITE, MV_EVASION>(pos, mlist, target)
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: generate_pawn_moves<BLACK, MV_EVASION>(pos, mlist, target));
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mlist = generate_moves<KNIGHT>(pos, mlist, us, target);
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mlist = generate_moves<BISHOP>(pos, mlist, us, target);
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mlist = generate_moves<ROOK>(pos, mlist, us, target);
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return generate_moves<QUEEN>(pos, mlist, us, target);
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}
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/// generate<MV_LEGAL> generates all the legal moves in the given position
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template<>
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MoveStack* generate<MV_LEGAL>(const Position& pos, MoveStack* mlist) {
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MoveStack *last, *cur = mlist;
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Bitboard pinned = pos.pinned_pieces();
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last = pos.in_check() ? generate<MV_EVASION>(pos, mlist)
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: generate<MV_NON_EVASION>(pos, mlist);
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while (cur != last)
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if (!pos.pl_move_is_legal(cur->move, pinned))
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cur->move = (--last)->move;
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else
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cur++;
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return last;
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}
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