X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=cc320b4b3e45d55aba64cbc2194f71795ba5d35f;hp=6885b135cafad835c691087a336ba9d66708228e;hb=8b0fee9998e2ae530fa57e55f6cf145779aef3d0;hpb=490f67a3f89449e243c3e85feb13679f388d9e22 diff --git a/src/position.cpp b/src/position.cpp index 6885b135..cc320b4b 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -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) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 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 @@ -19,29 +19,21 @@ #include #include -#include +#include // For std::memset #include -#include #include #include "bitcount.h" +#include "misc.h" #include "movegen.h" -#include "notation.h" #include "position.h" #include "psqtab.h" -#include "rkiss.h" #include "thread.h" #include "tt.h" +#include "uci.h" using std::string; -using std::cout; -using std::endl; -static const string PieceToChar(" PNBRQK pnbrqk"); - -CACHE_LINE_ALIGNMENT - -Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; Value PieceValue[PHASE_NB][PIECE_NB] = { { VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg }, { VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } }; @@ -50,16 +42,19 @@ namespace Zobrist { Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; Key enpassant[FILE_NB]; - Key castle[CASTLE_RIGHT_NB]; + Key castling[CASTLING_RIGHT_NB]; Key side; Key exclusion; } -Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion;} +Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion; } namespace { -// min_attacker() is an helper function used by see() to locate the least +const string PieceToChar(" PNBRQK pnbrqk"); +Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; + +// min_attacker() is a helper function used by see() to locate the least // valuable attacker for the side to move, remove the attacker we just found // from the bitboards and scan for new X-ray attacks behind it. @@ -85,7 +80,7 @@ PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stm template<> FORCE_INLINE PieceType min_attacker(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) { - return KING; // No need to update bitboards, it is the last cycle + return KING; // No need to update bitboards: it is the last cycle } } // namespace @@ -98,7 +93,7 @@ CheckInfo::CheckInfo(const Position& pos) { Color them = ~pos.side_to_move(); ksq = pos.king_square(them); - pinned = pos.pinned_pieces(); + pinned = pos.pinned_pieces(pos.side_to_move()); dcCandidates = pos.discovered_check_candidates(); checkSq[PAWN] = pos.attacks_from(ksq, them); @@ -110,45 +105,69 @@ CheckInfo::CheckInfo(const Position& pos) { } +/// operator<<(Position) returns an ASCII representation of the position + +std::ostream& operator<<(std::ostream& os, const Position& pos) { + + os << "\n +---+---+---+---+---+---+---+---+\n"; + + for (Rank r = RANK_8; r >= RANK_1; --r) + { + for (File f = FILE_A; f <= FILE_H; ++f) + os << " | " << PieceToChar[pos.piece_on(make_square(f, r))]; + + os << " |\n +---+---+---+---+---+---+---+---+\n"; + } + + os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase + << std::setfill('0') << std::setw(16) << pos.st->key << std::dec << "\nCheckers: "; + + for (Bitboard b = pos.checkers(); b; ) + os << UCI::square(pop_lsb(&b)) << " "; + + return os; +} + + /// Position::init() initializes at startup the various arrays used to compute /// hash keys and the piece square tables. The latter is a two-step operation: -/// First, the white halves of the tables are copied from PSQT[] tables. Second, -/// the black halves of the tables are initialized by flipping and changing the -/// sign of the white scores. +/// Firstly, the white halves of the tables are copied from PSQT[] tables. +/// Secondly, the black halves of the tables are initialized by flipping and +/// changing the sign of the white scores. void Position::init() { - RKISS rk; + PRNG rng(1070372); - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) - for (Square s = SQ_A1; s <= SQ_H8; s++) - Zobrist::psq[c][pt][s] = rk.rand(); + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) + for (Square s = SQ_A1; s <= SQ_H8; ++s) + Zobrist::psq[c][pt][s] = rng.rand(); - for (File f = FILE_A; f <= FILE_H; f++) - Zobrist::enpassant[f] = rk.rand(); + for (File f = FILE_A; f <= FILE_H; ++f) + Zobrist::enpassant[f] = rng.rand(); - for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++) + for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr) { Bitboard b = cr; while (b) { - Key k = Zobrist::castle[1ULL << pop_lsb(&b)]; - Zobrist::castle[cr] ^= k ? k : rk.rand(); + Key k = Zobrist::castling[1ULL << pop_lsb(&b)]; + Zobrist::castling[cr] ^= k ? k : rng.rand(); } } - Zobrist::side = rk.rand(); - Zobrist::exclusion = rk.rand(); + Zobrist::side = rng.rand(); + Zobrist::exclusion = rng.rand(); - for (PieceType pt = PAWN; pt <= KING; pt++) + for (PieceType pt = PAWN; pt <= KING; ++pt) { PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt]; PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt]; Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]); - for (Square s = SQ_A1; s <= SQ_H8; s++) + for (Square s = SQ_A1; s <= SQ_H8; ++s) { psq[WHITE][pt][ s] = (v + PSQT[pt][s]); psq[BLACK][pt][~s] = -(v + PSQT[pt][s]); @@ -157,9 +176,8 @@ void Position::init() { } -/// Position::operator=() creates a copy of 'pos'. We want the new born Position -/// object do not depend on any external data so we detach state pointer from -/// the source one. +/// Position::operator=() creates a copy of 'pos' but detaching the state pointer +/// from the source to be self-consistent and not depending on any external data. Position& Position::operator=(const Position& pos) { @@ -174,6 +192,21 @@ Position& Position::operator=(const Position& pos) { } +/// Position::clear() erases the position object to a pristine state, with an +/// empty board, white to move, and no castling rights. + +void Position::clear() { + + std::memset(this, 0, sizeof(Position)); + startState.epSquare = SQ_NONE; + st = &startState; + + for (int i = 0; i < PIECE_TYPE_NB; ++i) + for (int j = 0; j < 16; ++j) + pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE; +} + + /// Position::set() initializes the position object with the given FEN string. /// This function is not very robust - make sure that input FENs are correct, /// this is assumed to be the responsibility of the GUI. @@ -185,11 +218,11 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { A FEN string contains six fields separated by a space. The fields are: 1) Piece placement (from white's perspective). Each rank is described, starting - with rank 8 and ending with rank 1; within each rank, the contents of each + with rank 8 and ending with rank 1. Within each rank, the contents of each square are described from file A through file H. Following the Standard Algebraic Notation (SAN), each piece is identified by a single letter taken from the standard English names. White pieces are designated using upper-case - letters ("PNBRQK") while Black take lowercase ("pnbrqk"). Blank squares are + letters ("PNBRQK") whilst Black uses lowercase ("pnbrqk"). Blank squares are noted using digits 1 through 8 (the number of blank squares), and "/" separates ranks. @@ -213,8 +246,8 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { incremented after Black's move. */ - char col, row, token; - size_t p; + unsigned char col, row, token; + size_t idx; Square sq = SQ_A8; std::istringstream ss(fenStr); @@ -230,10 +263,10 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { else if (token == '/') sq -= Square(16); - else if ((p = PieceToChar.find(token)) != string::npos) + else if ((idx = PieceToChar.find(token)) != string::npos) { - put_piece(sq, color_of(Piece(p)), type_of(Piece(p))); - sq++; + put_piece(sq, color_of(Piece(idx)), type_of(Piece(idx))); + ++sq; } } @@ -255,25 +288,25 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { token = char(toupper(token)); if (token == 'K') - for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; rsq--) {} + for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; --rsq) {} else if (token == 'Q') - for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; rsq++) {} + for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; ++rsq) {} else if (token >= 'A' && token <= 'H') - rsq = File(token - 'A') | relative_rank(c, RANK_1); + rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); else continue; - set_castle_right(c, rsq); + set_castling_right(c, rsq); } // 4. En passant square. Ignore if no pawn capture is possible if ( ((ss >> col) && (col >= 'a' && col <= 'h')) && ((ss >> row) && (row == '3' || row == '6'))) { - st->epSquare = File(col - 'a') | Rank(row - '1'); + st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))) st->epSquare = SQ_NONE; @@ -284,205 +317,204 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { // Convert from fullmove starting from 1 to ply starting from 0, // handle also common incorrect FEN with fullmove = 0. - gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK); - - st->key = compute_key(); - st->pawnKey = compute_pawn_key(); - st->materialKey = compute_material_key(); - st->psq = compute_psq_score(); - st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); - st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); - st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); + gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK); + chess960 = isChess960; thisThread = th; + set_state(st); assert(pos_is_ok()); } -/// Position::set_castle_right() is an helper function used to set castling +/// Position::set_castling_right() is a helper function used to set castling /// rights given the corresponding color and the rook starting square. -void Position::set_castle_right(Color c, Square rfrom) { +void Position::set_castling_right(Color c, Square rfrom) { Square kfrom = king_square(c); CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE; - CastleRight cr = make_castle_right(c, cs); + CastlingRight cr = (c | cs); - st->castleRights |= cr; - castleRightsMask[kfrom] |= cr; - castleRightsMask[rfrom] |= cr; - castleRookSquare[c][cs] = rfrom; + st->castlingRights |= cr; + castlingRightsMask[kfrom] |= cr; + castlingRightsMask[rfrom] |= cr; + castlingRookSquare[cr] = rfrom; Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1); Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1); - for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); s++) + for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s) if (s != kfrom && s != rfrom) - castlePath[c][cs] |= s; + castlingPath[cr] |= s; - for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); s++) + for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s) if (s != kfrom && s != rfrom) - castlePath[c][cs] |= s; + castlingPath[cr] |= s; } -/// Position::fen() returns a FEN representation of the position. In case -/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function. +/// Position::set_state() computes the hash keys of the position, and other +/// data that once computed is updated incrementally as moves are made. +/// The function is only used when a new position is set up, and to verify +/// the correctness of the StateInfo data when running in debug mode. + +void Position::set_state(StateInfo* si) const { + + si->key = si->pawnKey = si->materialKey = 0; + si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO; + si->psq = SCORE_ZERO; + + si->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); + + for (Bitboard b = pieces(); b; ) + { + Square s = pop_lsb(&b); + Piece pc = piece_on(s); + si->key ^= Zobrist::psq[color_of(pc)][type_of(pc)][s]; + si->psq += psq[color_of(pc)][type_of(pc)][s]; + } + + if (ep_square() != SQ_NONE) + si->key ^= Zobrist::enpassant[file_of(ep_square())]; + + if (sideToMove == BLACK) + si->key ^= Zobrist::side; + + si->key ^= Zobrist::castling[st->castlingRights]; + + for (Bitboard b = pieces(PAWN); b; ) + { + Square s = pop_lsb(&b); + si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s]; + } + + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) + for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt) + si->materialKey ^= Zobrist::psq[c][pt][cnt]; + + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt) + si->nonPawnMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt]; +} + + +/// Position::fen() returns a FEN representation of the position. In case of +/// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function. const string Position::fen() const { + int emptyCnt; std::ostringstream ss; - for (Rank rank = RANK_8; rank >= RANK_1; rank--) + for (Rank r = RANK_8; r >= RANK_1; --r) { - for (File file = FILE_A; file <= FILE_H; file++) + for (File f = FILE_A; f <= FILE_H; ++f) { - Square sq = file | rank; - - if (is_empty(sq)) - { - int emptyCnt = 1; - - for ( ; file < FILE_H && is_empty(sq++); file++) - emptyCnt++; + for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f) + ++emptyCnt; + if (emptyCnt) ss << emptyCnt; - } - else - ss << PieceToChar[piece_on(sq)]; + + if (f <= FILE_H) + ss << PieceToChar[piece_on(make_square(f, r))]; } - if (rank > RANK_1) + if (r > RANK_1) ss << '/'; } ss << (sideToMove == WHITE ? " w " : " b "); if (can_castle(WHITE_OO)) - ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K'); + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | KING_SIDE))) : 'K'); if (can_castle(WHITE_OOO)) - ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q'); + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE))) : 'Q'); if (can_castle(BLACK_OO)) - ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k'); + ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | KING_SIDE))) : 'k'); if (can_castle(BLACK_OOO)) - ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q'); + ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE))) : 'q'); - if (st->castleRights == CASTLES_NONE) + if (!can_castle(WHITE) && !can_castle(BLACK)) ss << '-'; - ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") - << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2; + ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::square(ep_square()) + " ") + << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2; return ss.str(); } -/// Position::pretty() returns an ASCII representation of the position to be -/// printed to the standard output together with the move's san notation. +/// Position::game_phase() calculates the game phase interpolating total non-pawn +/// material between endgame and midgame limits. -const string Position::pretty(Move move) const { +Phase Position::game_phase() const { - const string dottedLine = "\n+---+---+---+---+---+---+---+---+"; - const string twoRows = dottedLine + "\n| | . | | . | | . | | . |" - + dottedLine + "\n| . | | . | | . | | . | |"; + Value npm = st->nonPawnMaterial[WHITE] + st->nonPawnMaterial[BLACK]; - string brd = twoRows + twoRows + twoRows + twoRows + dottedLine; + npm = std::max(EndgameLimit, std::min(npm, MidgameLimit)); - for (Bitboard b = pieces(); b; ) - { - Square s = pop_lsb(&b); - brd[513 - 68 * rank_of(s) + 4 * file_of(s)] = PieceToChar[piece_on(s)]; - } - - std::ostringstream ss; - - if (move) - ss << "\nMove: " << (sideToMove == BLACK ? ".." : "") - << move_to_san(*const_cast(this), move); - - ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase - << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: "; - - for (Bitboard b = checkers(); b; ) - ss << square_to_string(pop_lsb(&b)) << " "; - - ss << "\nLegal moves: "; - for (MoveList it(*this); *it; ++it) - ss << move_to_san(*const_cast(this), *it) << " "; - - return ss.str(); + return Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit)); } -/// Position:hidden_checkers() returns a bitboard of all pinned / discovery check -/// pieces, according to the call parameters. Pinned pieces protect our king, -/// discovery check pieces attack the enemy king. +/// Position::check_blockers() returns a bitboard of all the pieces with color +/// 'c' that are blocking check on the king with color 'kingColor'. A piece +/// blocks a check if removing that piece from the board would result in a +/// position where the king is in check. A check blocking piece can be either a +/// pinned or a discovered check piece, according if its color 'c' is the same +/// or the opposite of 'kingColor'. -Bitboard Position::hidden_checkers(Square ksq, Color c) const { +Bitboard Position::check_blockers(Color c, Color kingColor) const { Bitboard b, pinners, result = 0; + Square ksq = king_square(kingColor); - // Pinners are sliders that give check when pinned piece is removed + // Pinners are sliders that give check when a pinned piece is removed pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq]) - | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(c); + | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(~kingColor); while (pinners) { b = between_bb(ksq, pop_lsb(&pinners)) & pieces(); if (!more_than_one(b)) - result |= b & pieces(sideToMove); + result |= b & pieces(c); } return result; } /// Position::attackers_to() computes a bitboard of all pieces which attack a -/// given square. Slider attacks use occ bitboard as occupancy. - -Bitboard Position::attackers_to(Square s, Bitboard occ) const { - - return (attacks_from(s, BLACK) & pieces(WHITE, PAWN)) - | (attacks_from(s, WHITE) & pieces(BLACK, PAWN)) - | (attacks_from(s) & pieces(KNIGHT)) - | (attacks_bb(s, occ) & pieces(ROOK, QUEEN)) - | (attacks_bb(s, occ) & pieces(BISHOP, QUEEN)) - | (attacks_from(s) & pieces(KING)); -} +/// given square. Slider attacks use the occupied bitboard to indicate occupancy. +Bitboard Position::attackers_to(Square s, Bitboard occupied) const { -/// Position::attacks_from() computes a bitboard of all attacks of a given piece -/// put in a given square. Slider attacks use occ bitboard as occupancy. - -Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { - - assert(is_ok(s)); - - switch (type_of(p)) - { - case BISHOP: return attacks_bb(s, occ); - case ROOK : return attacks_bb(s, occ); - case QUEEN : return attacks_bb(s, occ) | attacks_bb(s, occ); - default : return StepAttacksBB[p][s]; - } + return (attacks_from(s, BLACK) & pieces(WHITE, PAWN)) + | (attacks_from(s, WHITE) & pieces(BLACK, PAWN)) + | (attacks_from(s) & pieces(KNIGHT)) + | (attacks_bb(s, occupied) & pieces(ROOK, QUEEN)) + | (attacks_bb(s, occupied) & pieces(BISHOP, QUEEN)) + | (attacks_from(s) & pieces(KING)); } -/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal +/// Position::legal() tests whether a pseudo-legal move is legal -bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { +bool Position::legal(Move m, Bitboard pinned) const { assert(is_ok(m)); - assert(pinned == pinned_pieces()); + assert(pinned == pinned_pieces(sideToMove)); Color us = sideToMove; Square from = from_sq(m); - assert(color_of(piece_moved(m)) == us); + assert(color_of(moved_piece(m)) == us); assert(piece_on(king_square(us)) == make_piece(us, KING)); // En passant captures are a tricky special case. Because they are rather @@ -490,45 +522,44 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { // the move is made. if (type_of(m) == ENPASSANT) { - Color them = ~us; - Square to = to_sq(m); - Square capsq = to + pawn_push(them); Square ksq = king_square(us); - Bitboard b = (pieces() ^ from ^ capsq) | to; + Square to = to_sq(m); + Square capsq = to - pawn_push(us); + Bitboard occupied = (pieces() ^ from ^ capsq) | to; assert(to == ep_square()); - assert(piece_moved(m) == make_piece(us, PAWN)); - assert(piece_on(capsq) == make_piece(them, PAWN)); + assert(moved_piece(m) == make_piece(us, PAWN)); + assert(piece_on(capsq) == make_piece(~us, PAWN)); assert(piece_on(to) == NO_PIECE); - return !(attacks_bb< ROOK>(ksq, b) & pieces(them, QUEEN, ROOK)) - && !(attacks_bb(ksq, b) & pieces(them, QUEEN, BISHOP)); + return !(attacks_bb< ROOK>(ksq, occupied) & pieces(~us, QUEEN, ROOK)) + && !(attacks_bb(ksq, occupied) & pieces(~us, QUEEN, BISHOP)); } // If the moving piece is a king, check whether the destination // square is attacked by the opponent. Castling moves are checked // for legality during move generation. if (type_of(piece_on(from)) == KING) - return type_of(m) == CASTLE || !(attackers_to(to_sq(m)) & pieces(~us)); + return type_of(m) == CASTLING || !(attackers_to(to_sq(m)) & pieces(~us)); // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. return !pinned || !(pinned & from) - || squares_aligned(from, to_sq(m), king_square(us)); + || aligned(from, to_sq(m), king_square(us)); } -/// Position::is_pseudo_legal() takes a random move and tests whether the move -/// is pseudo legal. It is used to validate moves from TT that can be corrupted +/// Position::pseudo_legal() takes a random move and tests whether the move is +/// pseudo legal. It is used to validate moves from TT that can be corrupted /// due to SMP concurrent access or hash position key aliasing. -bool Position::is_pseudo_legal(const Move m) const { +bool Position::pseudo_legal(const Move m) const { Color us = sideToMove; Square from = from_sq(m); Square to = to_sq(m); - Piece pc = piece_moved(m); + Piece pc = moved_piece(m); // Use a slower but simpler function for uncommon cases if (type_of(m) != NORMAL) @@ -538,7 +569,7 @@ bool Position::is_pseudo_legal(const Move m) const { if (promotion_type(m) - 2 != NO_PIECE_TYPE) return false; - // If the from square is not occupied by a piece belonging to the side to + // If the 'from' square is not occupied by a piece belonging to the side to // move, the move is obviously not legal. if (pc == NO_PIECE || color_of(pc) != us) return false; @@ -550,71 +581,27 @@ bool Position::is_pseudo_legal(const Move m) const { // Handle the special case of a pawn move if (type_of(pc) == PAWN) { - // Move direction must be compatible with pawn color - int direction = to - from; - if ((us == WHITE) != (direction > 0)) - return false; - // We have already handled promotion moves, so destination - // cannot be on the 8/1th rank. - if (rank_of(to) == RANK_8 || rank_of(to) == RANK_1) + // cannot be on the 8th/1st rank. + if (rank_of(to) == relative_rank(us, RANK_8)) return false; - // Proceed according to the square delta between the origin and - // destination squares. - switch (direction) - { - case DELTA_NW: - case DELTA_NE: - case DELTA_SW: - case DELTA_SE: - // Capture. The destination square must be occupied by an enemy - // piece (en passant captures was handled earlier). - if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us) - return false; + if ( !(attacks_from(from, us) & pieces(~us) & to) // Not a capture - // From and to files must be one file apart, avoids a7h5 - if (abs(file_of(from) - file_of(to)) != 1) - return false; - break; + && !((from + pawn_push(us) == to) && empty(to)) // Not a single push - case DELTA_N: - case DELTA_S: - // Pawn push. The destination square must be empty. - if (!is_empty(to)) - return false; - break; - - case DELTA_NN: - // Double white pawn push. The destination square must be on the fourth - // rank, and both the destination square and the square between the - // source and destination squares must be empty. - if ( rank_of(to) != RANK_4 - || !is_empty(to) - || !is_empty(from + DELTA_N)) - return false; - break; - - case DELTA_SS: - // Double black pawn push. The destination square must be on the fifth - // rank, and both the destination square and the square between the - // source and destination squares must be empty. - if ( rank_of(to) != RANK_5 - || !is_empty(to) - || !is_empty(from + DELTA_S)) + && !( (from + 2 * pawn_push(us) == to) // Not a double push + && (rank_of(from) == relative_rank(us, RANK_2)) + && empty(to) + && empty(to - pawn_push(us)))) return false; - break; - - default: - return false; - } } else if (!(attacks_from(pc, from) & to)) return false; // Evasions generator already takes care to avoid some kind of illegal moves - // and pl_move_is_legal() relies on this. So we have to take care that the - // same kind of moves are filtered out here. + // and legal() relies on this. We therefore have to take care that the same + // kind of moves are filtered out here. if (checkers()) { if (type_of(pc) != KING) @@ -627,8 +614,8 @@ bool Position::is_pseudo_legal(const Move m) const { if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to)) return false; } - // In case of king moves under check we have to remove king so to catch - // as invalid moves like b1a1 when opposite queen is on c1. + // In case of king moves under check we have to remove king so as to catch + // invalid moves like b1a1 when opposite queen is on c1. else if (attackers_to(to, pieces() ^ from) & pieces(~us)) return false; } @@ -637,64 +624,57 @@ bool Position::is_pseudo_legal(const Move m) const { } -/// Position::move_gives_check() tests whether a pseudo-legal move gives a check +/// Position::gives_check() tests whether a pseudo-legal move gives a check -bool Position::move_gives_check(Move m, const CheckInfo& ci) const { +bool Position::gives_check(Move m, const CheckInfo& ci) const { assert(is_ok(m)); assert(ci.dcCandidates == discovered_check_candidates()); - assert(color_of(piece_moved(m)) == sideToMove); + assert(color_of(moved_piece(m)) == sideToMove); Square from = from_sq(m); Square to = to_sq(m); PieceType pt = type_of(piece_on(from)); - // Direct check ? + // Is there a direct check? if (ci.checkSq[pt] & to) return true; - // Discovery check ? - if (unlikely(ci.dcCandidates) && (ci.dcCandidates & from)) - { - // For pawn and king moves we need to verify also direction - if ( (pt != PAWN && pt != KING) - || !squares_aligned(from, to, king_square(~sideToMove))) - return true; - } - - // Can we skip the ugly special cases ? - if (type_of(m) == NORMAL) - return false; - - Color us = sideToMove; - Square ksq = king_square(~us); + // Is there a discovered check? + if ( ci.dcCandidates + && (ci.dcCandidates & from) + && !aligned(from, to, ci.ksq)) + return true; switch (type_of(m)) { + case NORMAL: + return false; + case PROMOTION: - return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq; + return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq; - // En passant capture with check ? We have already handled the case - // of direct checks and ordinary discovered check, the only case we + // En passant capture with check? We have already handled the case + // of direct checks and ordinary discovered check, so the only case we // need to handle is the unusual case of a discovered check through // the captured pawn. case ENPASSANT: { - Square capsq = file_of(to) | rank_of(from); + Square capsq = make_square(file_of(to), rank_of(from)); Bitboard b = (pieces() ^ from ^ capsq) | to; - return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK)) - | (attacks_bb(ksq, b) & pieces(us, QUEEN, BISHOP)); + return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK)) + | (attacks_bb(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP)); } - case CASTLE: + case CASTLING: { Square kfrom = from; - Square rfrom = to; // 'King captures the rook' notation - Square kto = relative_square(us, rfrom > kfrom ? SQ_G1 : SQ_C1); - Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1); + Square rfrom = to; // Castling is encoded as 'King captures the rook' + Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1); + Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1); - return (PseudoAttacks[ROOK][rto] & ksq) - && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ksq); + return (PseudoAttacks[ROOK][rto] & ci.ksq) + && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq); } default: assert(false); @@ -710,7 +690,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const { void Position::do_move(Move m, StateInfo& newSt) { CheckInfo ci(*this); - do_move(m, newSt, ci, move_gives_check(m, ci)); + do_move(m, newSt, ci, gives_check(m, ci)); } void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) { @@ -718,12 +698,12 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI assert(is_ok(m)); assert(&newSt != st); - nodes++; + ++nodes; Key k = st->key; - // Copy some fields of old state to our new StateInfo object except the ones - // which are going to be recalculated from scratch anyway, then switch our state - // pointer to point to the new, ready to be updated, state. + // Copy some fields of the old state to our new StateInfo object except the + // ones which are going to be recalculated from scratch anyway and then switch + // our state pointer to point to the new (ready to be updated) state. std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t)); newSt.previous = st; @@ -732,11 +712,11 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI // Update side to move k ^= Zobrist::side; - // Increment ply counters.In particular rule50 will be later reset it to zero + // Increment ply counters. In particular, rule50 will be reset to zero later on // in case of a capture or a pawn move. - gamePly++; - st->rule50++; - st->pliesFromNull++; + ++gamePly; + ++st->rule50; + ++st->pliesFromNull; Color us = sideToMove; Color them = ~us; @@ -744,35 +724,31 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI Square to = to_sq(m); Piece pc = piece_on(from); PieceType pt = type_of(pc); - PieceType capture = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to)); + PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to)); assert(color_of(pc) == us); - assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE); - assert(capture != KING); + assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLING); + assert(captured != KING); - if (type_of(m) == CASTLE) + if (type_of(m) == CASTLING) { assert(pc == make_piece(us, KING)); - bool kingSide = to > from; - Square rfrom = to; // Castle is encoded as "king captures friendly rook" - Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); - to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); - capture = NO_PIECE_TYPE; - - do_castle(from, to, rfrom, rto); + Square rfrom, rto; + do_castling(from, to, rfrom, rto); + captured = NO_PIECE_TYPE; st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom]; k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto]; } - if (capture) + if (captured) { Square capsq = to; // If the captured piece is a pawn, update pawn hash key, otherwise // update non-pawn material. - if (capture == PAWN) + if (captured == PAWN) { if (type_of(m) == ENPASSANT) { @@ -790,18 +766,18 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st->pawnKey ^= Zobrist::psq[them][PAWN][capsq]; } else - st->npMaterial[them] -= PieceValue[MG][capture]; + st->nonPawnMaterial[them] -= PieceValue[MG][captured]; // Update board and piece lists - remove_piece(capsq, them, capture); + remove_piece(capsq, them, captured); // Update material hash key and prefetch access to materialTable - k ^= Zobrist::psq[them][capture][capsq]; - st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]]; + k ^= Zobrist::psq[them][captured][capsq]; + st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]]; prefetch((char*)thisThread->materialTable[st->materialKey]); // Update incremental scores - st->psq -= psq[them][capture][capsq]; + st->psq -= psq[them][captured][capsq]; // Reset rule 50 counter st->rule50 = 0; @@ -817,25 +793,22 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st->epSquare = SQ_NONE; } - // Update castle rights if needed - if (st->castleRights && (castleRightsMask[from] | castleRightsMask[to])) + // Update castling rights if needed + if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to])) { - int cr = castleRightsMask[from] | castleRightsMask[to]; - k ^= Zobrist::castle[st->castleRights & cr]; - st->castleRights &= ~cr; + int cr = castlingRightsMask[from] | castlingRightsMask[to]; + k ^= Zobrist::castling[st->castlingRights & cr]; + st->castlingRights &= ~cr; } - // Prefetch TT access as soon as we know the new hash key - prefetch((char*)TT.first_entry(k)); - - // Move the piece. The tricky Chess960 castle is handled earlier - if (type_of(m) != CASTLE) + // Move the piece. The tricky Chess960 castling is handled earlier + if (type_of(m) != CASTLING) move_piece(from, to, us, pt); // If the moving piece is a pawn do some special extra work if (pt == PAWN) { - // Set en-passant square, only if moved pawn can be captured + // Set en-passant square if the moved pawn can be captured if ( (int(to) ^ int(from)) == 16 && (attacks_from(from + pawn_push(us), us) & pieces(them, PAWN))) { @@ -843,7 +816,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI k ^= Zobrist::enpassant[file_of(st->epSquare)]; } - if (type_of(m) == PROMOTION) + else if (type_of(m) == PROMOTION) { PieceType promotion = promotion_type(m); @@ -863,7 +836,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st->psq += psq[us][promotion][to] - psq[us][PAWN][to]; // Update material - st->npMaterial[us] += PieceValue[MG][promotion]; + st->nonPawnMaterial[us] += PieceValue[MG][promotion]; } // Update pawn hash key and prefetch access to pawnsTable @@ -878,12 +851,12 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st->psq += psq[us][pt][to] - psq[us][pt][from]; // Set capture piece - st->capturedType = capture; + st->capturedType = captured; // Update the key with the final value st->key = k; - // Update checkers bitboard, piece must be already moved + // Update checkers bitboard: piece must be already moved due to attacks_from() st->checkersBB = 0; if (moveIsCheck) @@ -896,7 +869,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI if (ci.checkSq[pt] & to) st->checkersBB |= to; - // Discovery checks + // Discovered checks if (ci.dcCandidates && (ci.dcCandidates & from)) { if (pt != ROOK) @@ -924,77 +897,75 @@ void Position::undo_move(Move m) { sideToMove = ~sideToMove; Color us = sideToMove; - Color them = ~us; Square from = from_sq(m); Square to = to_sq(m); PieceType pt = type_of(piece_on(to)); - PieceType capture = st->capturedType; - assert(is_empty(from) || type_of(m) == CASTLE); - assert(capture != KING); + assert(empty(from) || type_of(m) == CASTLING); + assert(st->capturedType != KING); if (type_of(m) == PROMOTION) { - PieceType promotion = promotion_type(m); - - assert(promotion == pt); + assert(pt == promotion_type(m)); assert(relative_rank(us, to) == RANK_8); - assert(promotion >= KNIGHT && promotion <= QUEEN); + assert(promotion_type(m) >= KNIGHT && promotion_type(m) <= QUEEN); - remove_piece(to, us, promotion); + remove_piece(to, us, promotion_type(m)); put_piece(to, us, PAWN); pt = PAWN; } - if (type_of(m) == CASTLE) + if (type_of(m) == CASTLING) { - bool kingSide = to > from; - Square rfrom = to; // Castle is encoded as "king captures friendly rook" - Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); - to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); - capture = NO_PIECE_TYPE; - pt = KING; - do_castle(to, from, rto, rfrom); + Square rfrom, rto; + do_castling(from, to, rfrom, rto); } else - move_piece(to, from, us, pt); // Put the piece back at the source square - - if (capture) { - Square capsq = to; + move_piece(to, from, us, pt); // Put the piece back at the source square - if (type_of(m) == ENPASSANT) + if (st->capturedType) { - capsq -= pawn_push(us); + Square capsq = to; - assert(pt == PAWN); - assert(to == st->previous->epSquare); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(capsq) == NO_PIECE); - } + if (type_of(m) == ENPASSANT) + { + capsq -= pawn_push(us); - put_piece(capsq, them, capture); // Restore the captured piece + assert(pt == PAWN); + assert(to == st->previous->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(capsq) == NO_PIECE); + } + + put_piece(capsq, ~us, st->capturedType); // Restore the captured piece + } } // Finally point our state pointer back to the previous state st = st->previous; - gamePly--; + --gamePly; assert(pos_is_ok()); } -/// Position::do_castle() is a helper used to do/undo a castling move. This +/// Position::do_castling() is a helper used to do/undo a castling move. This /// is a bit tricky, especially in Chess960. +template +void Position::do_castling(Square from, Square& to, Square& rfrom, Square& rto) { -void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) { + bool kingSide = to > from; + rfrom = to; // Castling is encoded as "king captures friendly rook" + rto = relative_square(sideToMove, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(sideToMove, kingSide ? SQ_G1 : SQ_C1); // Remove both pieces first since squares could overlap in Chess960 - remove_piece(kfrom, sideToMove, KING); - remove_piece(rfrom, sideToMove, ROOK); - board[kfrom] = board[rfrom] = NO_PIECE; // Since remove_piece doesn't do it for us - put_piece(kto, sideToMove, KING); - put_piece(rto, sideToMove, ROOK); + remove_piece(Do ? from : to, sideToMove, KING); + remove_piece(Do ? rfrom : rto, sideToMove, ROOK); + board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us + put_piece(Do ? to : from, sideToMove, KING); + put_piece(Do ? rto : rfrom, sideToMove, ROOK); } @@ -1019,7 +990,7 @@ void Position::do_null_move(StateInfo& newSt) { st->key ^= Zobrist::side; prefetch((char*)TT.first_entry(st->key)); - st->rule50++; + ++st->rule50; st->pliesFromNull = 0; sideToMove = ~sideToMove; @@ -1036,30 +1007,48 @@ void Position::undo_null_move() { } +/// Position::key_after() computes the new hash key after the given move. Needed +/// for speculative prefetch. It doesn't recognize special moves like castling, +/// en-passant and promotions. + +Key Position::key_after(Move m) const { + + Color us = sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(from)); + PieceType captured = type_of(piece_on(to)); + Key k = st->key ^ Zobrist::side; + + if (captured) + k ^= Zobrist::psq[~us][captured][to]; + + return k ^ Zobrist::psq[us][pt][to] ^ Zobrist::psq[us][pt][from]; +} + + /// Position::see() is a static exchange evaluator: It tries to estimate the -/// material gain or loss resulting from a move. Parameter 'asymmThreshold' takes -/// tempi into account. If the side who initiated the capturing sequence does the -/// last capture, he loses a tempo and if the result is below 'asymmThreshold' -/// the capturing sequence is considered bad. +/// material gain or loss resulting from a move. -int Position::see_sign(Move m) const { +Value Position::see_sign(Move m) const { assert(is_ok(m)); // Early return if SEE cannot be negative because captured piece value // is not less then capturing one. Note that king moves always return // here because king midgame value is set to 0. - if (PieceValue[MG][piece_moved(m)] <= PieceValue[MG][piece_on(to_sq(m))]) - return 1; + if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))]) + return VALUE_KNOWN_WIN; return see(m); } -int Position::see(Move m, int asymmThreshold) const { +Value Position::see(Move m) const { Square from, to; Bitboard occupied, attackers, stmAttackers; - int swapList[32], slIndex = 1; + Value swapList[32]; + int slIndex = 1; PieceType captured; Color stm; @@ -1067,15 +1056,15 @@ int Position::see(Move m, int asymmThreshold) const { from = from_sq(m); to = to_sq(m); - swapList[0] = PieceValue[MG][type_of(piece_on(to))]; + swapList[0] = PieceValue[MG][piece_on(to)]; stm = color_of(piece_on(from)); occupied = pieces() ^ from; - // Castle moves are implemented as king capturing the rook so cannot be - // handled correctly. Simply return 0 that is always the correct value + // Castling moves are implemented as king capturing the rook so cannot + // be handled correctly. Simply return VALUE_ZERO that is always correct // unless in the rare case the rook ends up under attack. - if (type_of(m) == CASTLE) - return 0; + if (type_of(m) == CASTLING) + return VALUE_ZERO; if (type_of(m) == ENPASSANT) { @@ -1106,181 +1095,49 @@ int Position::see(Move m, int asymmThreshold) const { // Add the new entry to the swap list swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; - slIndex++; // Locate and remove the next least valuable attacker captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); - stm = ~stm; - stmAttackers = attackers & pieces(stm); // Stop before processing a king capture - if (captured == KING && stmAttackers) + if (captured == KING) { - swapList[slIndex++] = QueenValueMg * 16; + if (stmAttackers == attackers) + ++slIndex; + break; } - } while (stmAttackers); + stm = ~stm; + stmAttackers = attackers & pieces(stm); + ++slIndex; - // If we are doing asymmetric SEE evaluation and the same side does the first - // and the last capture, he loses a tempo and gain must be at least worth - // 'asymmThreshold', otherwise we replace the score with a very low value, - // before negamaxing. - if (asymmThreshold) - for (int i = 0; i < slIndex; i += 2) - if (swapList[i] < asymmThreshold) - swapList[i] = - QueenValueMg * 16; + } while (stmAttackers); // Having built the swap list, we negamax through it to find the best // achievable score from the point of view of the side to move. while (--slIndex) - swapList[slIndex-1] = std::min(-swapList[slIndex], swapList[slIndex-1]); + swapList[slIndex - 1] = std::min(-swapList[slIndex], swapList[slIndex - 1]); return swapList[0]; } -/// Position::clear() erases the position object to a pristine state, with an -/// empty board, white to move, and no castling rights. - -void Position::clear() { - - std::memset(this, 0, sizeof(Position)); - startState.epSquare = SQ_NONE; - st = &startState; - - for (int i = 0; i < 8; i++) - for (int j = 0; j < 16; j++) - pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; -} - - -/// Position::compute_key() computes the hash key of the position. The hash -/// key is usually updated incrementally as moves are made and unmade, the -/// compute_key() function is only used when a new position is set up, and -/// to verify the correctness of the hash key when running in debug mode. - -Key Position::compute_key() const { - - Key k = Zobrist::castle[st->castleRights]; - - for (Bitboard b = pieces(); b; ) - { - Square s = pop_lsb(&b); - k ^= Zobrist::psq[color_of(piece_on(s))][type_of(piece_on(s))][s]; - } - - if (ep_square() != SQ_NONE) - k ^= Zobrist::enpassant[file_of(ep_square())]; - - if (sideToMove == BLACK) - k ^= Zobrist::side; - - return k; -} - - -/// Position::compute_pawn_key() computes the hash key of the position. The -/// hash key is usually updated incrementally as moves are made and unmade, -/// the compute_pawn_key() function is only used when a new position is set -/// up, and to verify the correctness of the pawn hash key when running in -/// debug mode. - -Key Position::compute_pawn_key() const { - - Key k = 0; - - for (Bitboard b = pieces(PAWN); b; ) - { - Square s = pop_lsb(&b); - k ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s]; - } - - return k; -} - - -/// Position::compute_material_key() computes the hash key of the position. -/// The hash key is usually updated incrementally as moves are made and unmade, -/// the compute_material_key() function is only used when a new position is set -/// up, and to verify the correctness of the material hash key when running in -/// debug mode. - -Key Position::compute_material_key() const { - - Key k = 0; - - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= QUEEN; pt++) - for (int cnt = 0; cnt < pieceCount[c][pt]; cnt++) - k ^= Zobrist::psq[c][pt][cnt]; - - return k; -} - - -/// Position::compute_psq_score() computes the incremental scores for the middle -/// game and the endgame. These functions are used to initialize the incremental -/// scores when a new position is set up, and to verify that the scores are correctly -/// updated by do_move and undo_move when the program is running in debug mode. - -Score Position::compute_psq_score() const { - - Score score = SCORE_ZERO; - - for (Bitboard b = pieces(); b; ) - { - Square s = pop_lsb(&b); - Piece pc = piece_on(s); - score += psq[color_of(pc)][type_of(pc)][s]; - } - - return score; -} - - -/// Position::compute_non_pawn_material() computes the total non-pawn middle -/// game material value for the given side. Material values are updated -/// incrementally during the search, this function is only used while -/// initializing a new Position object. - -Value Position::compute_non_pawn_material(Color c) const { - - Value value = VALUE_ZERO; - - for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) - value += pieceCount[c][pt] * PieceValue[MG][pt]; - - return value; -} - - -/// Position::is_draw() tests whether the position is drawn by repetition -/// or the 50 moves rule. It does not detect stalemates, this must be done -/// by the search. +/// Position::is_draw() tests whether the position is drawn by material, 50 moves +/// rule or repetition. It does not detect stalemates. bool Position::is_draw() const { - // Draw by the 50 moves rule? if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; - // Draw by repetition? - int i = 4, e = std::min(st->rule50, st->pliesFromNull); - - if (i <= e) + StateInfo* stp = st; + for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2) { - StateInfo* stp = st->previous->previous; - - do { - stp = stp->previous->previous; - - if (stp->key == st->key) - return true; - - i += 2; + stp = stp->previous->previous; - } while (i <= e); + if (stp->key == st->key) + return true; // Draw at first repetition } return false; @@ -1288,20 +1145,16 @@ bool Position::is_draw() const { /// Position::flip() flips position with the white and black sides reversed. This -/// is only useful for debugging especially for finding evaluation symmetry bugs. - -static char toggle_case(char c) { - return char(islower(c) ? toupper(c) : tolower(c)); -} +/// is only useful for debugging e.g. for finding evaluation symmetry bugs. void Position::flip() { string f, token; std::stringstream ss(fen()); - for (Rank rank = RANK_8; rank >= RANK_1; rank--) // Piece placement + for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement { - std::getline(ss, token, rank > RANK_1 ? '/' : ' '); + std::getline(ss, token, r > RANK_1 ? '/' : ' '); f.insert(0, token + (f.empty() ? " " : "/")); } @@ -1311,7 +1164,8 @@ void Position::flip() { ss >> token; // Castling availability f += token + " "; - std::transform(f.begin(), f.end(), f.begin(), toggle_case); + std::transform(f.begin(), f.end(), f.begin(), + [](char c) { return char(islower(c) ? toupper(c) : tolower(c)); }); ss >> token; // En passant square f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3")); @@ -1325,60 +1179,33 @@ void Position::flip() { } -/// Position::pos_is_ok() performs some consitency checks for the position object. +/// Position::pos_is_ok() performs some consistency checks for the position object. /// This is meant to be helpful when debugging. -bool Position::pos_is_ok(int* failedStep) const { - - int dummy, *step = failedStep ? failedStep : &dummy; +bool Position::pos_is_ok(int* step) const { - // What features of the position should be verified? + // Which parts of the position should be verified? const bool all = false; - const bool debugBitboards = all || false; - const bool debugKingCount = all || false; - const bool debugKingCapture = all || false; - const bool debugCheckerCount = all || false; - const bool debugKey = all || false; - const bool debugMaterialKey = all || false; - const bool debugPawnKey = all || false; - const bool debugIncrementalEval = all || false; - const bool debugNonPawnMaterial = all || false; - const bool debugPieceCounts = all || false; - const bool debugPieceList = all || false; - const bool debugCastleSquares = all || false; - - *step = 1; - - if (sideToMove != WHITE && sideToMove != BLACK) + const bool testBitboards = all || false; + const bool testState = all || false; + const bool testKingCount = all || false; + const bool testKingCapture = all || false; + const bool testPieceCounts = all || false; + const bool testPieceList = all || false; + const bool testCastlingSquares = all || false; + + if (step) + *step = 1; + + if ( (sideToMove != WHITE && sideToMove != BLACK) + || piece_on(king_square(WHITE)) != W_KING + || piece_on(king_square(BLACK)) != B_KING + || ( ep_square() != SQ_NONE + && relative_rank(sideToMove, ep_square()) != RANK_6)) return false; - if ((*step)++, piece_on(king_square(WHITE)) != W_KING) - return false; - - if ((*step)++, piece_on(king_square(BLACK)) != B_KING) - return false; - - if ((*step)++, debugKingCount) - { - int kingCount[COLOR_NB] = {}; - - for (Square s = SQ_A1; s <= SQ_H8; s++) - if (type_of(piece_on(s)) == KING) - kingCount[color_of(piece_on(s))]++; - - if (kingCount[0] != 1 || kingCount[1] != 1) - return false; - } - - if ((*step)++, debugKingCapture) - if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove)) - return false; - - if ((*step)++, debugCheckerCount && popcount(st->checkersBB) > 2) - return false; - - if ((*step)++, debugBitboards) + if (step && ++*step, testBitboards) { // The intersection of the white and black pieces must be empty if (pieces(WHITE) & pieces(BLACK)) @@ -1390,61 +1217,61 @@ bool Position::pos_is_ok(int* failedStep) const { return false; // Separate piece type bitboards must have empty intersections - for (PieceType p1 = PAWN; p1 <= KING; p1++) - for (PieceType p2 = PAWN; p2 <= KING; p2++) + for (PieceType p1 = PAWN; p1 <= KING; ++p1) + for (PieceType p2 = PAWN; p2 <= KING; ++p2) if (p1 != p2 && (pieces(p1) & pieces(p2))) return false; } - if ((*step)++, ep_square() != SQ_NONE && relative_rank(sideToMove, ep_square()) != RANK_6) - return false; - - if ((*step)++, debugKey && st->key != compute_key()) - return false; - - if ((*step)++, debugPawnKey && st->pawnKey != compute_pawn_key()) - return false; - - if ((*step)++, debugMaterialKey && st->materialKey != compute_material_key()) - return false; + if (step && ++*step, testState) + { + StateInfo si; + set_state(&si); + if ( st->key != si.key + || st->pawnKey != si.pawnKey + || st->materialKey != si.materialKey + || st->nonPawnMaterial[WHITE] != si.nonPawnMaterial[WHITE] + || st->nonPawnMaterial[BLACK] != si.nonPawnMaterial[BLACK] + || st->psq != si.psq + || st->checkersBB != si.checkersBB) + return false; + } - if ((*step)++, debugIncrementalEval && st->psq != compute_psq_score()) - return false; + if (step && ++*step, testKingCount) + if ( std::count(board, board + SQUARE_NB, W_KING) != 1 + || std::count(board, board + SQUARE_NB, B_KING) != 1) + return false; - if ((*step)++, debugNonPawnMaterial) - if ( st->npMaterial[WHITE] != compute_non_pawn_material(WHITE) - || st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if (step && ++*step, testKingCapture) + if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove)) return false; - if ((*step)++, debugPieceCounts) - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) + if (step && ++*step, testPieceCounts) + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) if (pieceCount[c][pt] != popcount(pieces(c, pt))) return false; - if ((*step)++, debugPieceList) - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) - for (int i = 0; i < pieceCount[c][pt]; i++) + if (step && ++*step, testPieceList) + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) + for (int i = 0; i < pieceCount[c][pt]; ++i) if ( board[pieceList[c][pt][i]] != make_piece(c, pt) || index[pieceList[c][pt][i]] != i) return false; - if ((*step)++, debugCastleSquares) - for (Color c = WHITE; c <= BLACK; c++) + if (step && ++*step, testCastlingSquares) + for (Color c = WHITE; c <= BLACK; ++c) for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1)) { - CastleRight cr = make_castle_right(c, s); - - if (!can_castle(cr)) + if (!can_castle(c | s)) continue; - if ( (castleRightsMask[king_square(c)] & cr) != cr - || piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK) - || castleRightsMask[castleRookSquare[c][s]] != cr) + if ( (castlingRightsMask[king_square(c)] & (c | s)) != (c | s) + || piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK) + || castlingRightsMask[castlingRookSquare[c | s]] != (c | s)) return false; } - *step = 0; return true; }