/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
////
#include <cassert>
-#include <iostream>
+#include <cstring>
#include <fstream>
+#include <iostream>
+#include "bitcount.h"
#include "mersenne.h"
#include "movegen.h"
#include "movepick.h"
#include "san.h"
#include "ucioption.h"
+using std::string;
+
////
//// Variables
////
-extern SearchStack EmptySearchStack;
-
int Position::castleRightsMask[64];
Key Position::zobrist[2][8][64];
copy(pos);
}
-Position::Position(const std::string& fen) {
+Position::Position(const string& fen) {
from_fen(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).
-void Position::from_fen(const std::string& fen) {
+void Position::from_fen(const string& fen) {
- static const std::string pieceLetters = "KQRBNPkqrbnp";
+ static const string pieceLetters = "KQRBNPkqrbnp";
static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP };
clear();
continue;
}
size_t idx = pieceLetters.find(fen[i]);
- if (idx == std::string::npos)
+ if (idx == string::npos)
{
std::cout << "Error in FEN at character " << i << std::endl;
return;
i++;
// En passant square
- if ( i < fen.length() - 2
+ if ( i <= fen.length() - 2
&& (fen[i] >= 'a' && fen[i] <= 'h')
&& (fen[i+1] == '3' || fen[i+1] == '6'))
- epSquare = square_from_string(fen.substr(i, 2));
+ st->epSquare = square_from_string(fen.substr(i, 2));
// Various initialisation
for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
find_checkers();
- key = compute_key();
- pawnKey = compute_pawn_key();
- materialKey = compute_material_key();
- mgValue = compute_mg_value();
- egValue = compute_eg_value();
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->key = compute_key();
+ st->pawnKey = compute_pawn_key();
+ st->materialKey = compute_material_key();
+ st->mgValue = compute_value<MidGame>();
+ st->egValue = compute_value<EndGame>();
+ st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
+ st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
}
/// Position::to_fen() converts the position object to a FEN string. This is
/// probably only useful for debugging.
-const std::string Position::to_fen() const {
+const string Position::to_fen() const {
- static const std::string pieceLetters = " PNBRQK pnbrqk";
- std::string fen;
+ static const string pieceLetters = " PNBRQK pnbrqk";
+ string fen;
int skip;
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
fen += (rank > RANK_1 ? '/' : ' ');
}
fen += (sideToMove == WHITE ? "w " : "b ");
- if (castleRights != NO_CASTLES)
+ if (st->castleRights != NO_CASTLES)
{
if (can_castle_kingside(WHITE)) fen += 'K';
if (can_castle_queenside(WHITE)) fen += 'Q';
void Position::print(Move m) const {
- static const std::string pieceLetters = " PNBRQK PNBRQK .";
+ static const string pieceLetters = " PNBRQK PNBRQK .";
// Check for reentrancy, as example when called from inside
// MovePicker that is used also here in move_to_san()
std::cout << std::endl;
if (m != MOVE_NONE)
{
- std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
+ string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
std::cout << "Move is: " << col << move_to_san(*this, m) << std::endl;
}
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
}
std::cout << "+---+---+---+---+---+---+---+---+" << std::endl
<< "Fen is: " << to_fen() << std::endl
- << "Key is: " << key << std::endl;
+ << "Key is: " << st->key << std::endl;
RequestPending = false;
}
/// Position::copy() creates a copy of the input position.
-void Position::copy(const Position &pos) {
+void Position::copy(const Position& pos) {
memcpy(this, &pos, sizeof(Position));
+ saveState(); // detach and copy state info
}
-/// Position:pinned_pieces() returns a bitboard of all pinned (against the
-/// king) pieces for the given color.
-Bitboard Position::pinned_pieces(Color c) const {
+/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the
+/// king) pieces for the given color and for the given pinner type. Or, when
+/// template parameter FindPinned is false, the pieces of the given color
+/// candidate for a discovery check against the enemy king.
+/// Note that checkersBB bitboard must be already updated.
- Square ksq = king_square(c);
- return hidden_checks<ROOK, true>(c, ksq) | hidden_checks<BISHOP, true>(c, ksq);
-}
+template<bool FindPinned>
+Bitboard Position::hidden_checkers(Color c) const {
+ Bitboard pinners, result = EmptyBoardBB;
-/// Position:discovered_check_candidates() returns a bitboard containing all
-/// pieces for the given side which are candidates for giving a discovered
-/// check. The code is almost the same as the function for finding pinned
-/// pieces.
+ // Pinned pieces protect our king, dicovery checks attack
+ // the enemy king.
+ Square ksq = king_square(FindPinned ? c : opposite_color(c));
-Bitboard Position::discovered_check_candidates(Color c) const {
+ // Pinners are sliders, not checkers, that give check when
+ // candidate pinned is removed.
+ pinners = (rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq])
+ | (bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]);
+
+ if (FindPinned && pinners)
+ pinners &= ~st->checkersBB;
+
+ while (pinners)
+ {
+ Square s = pop_1st_bit(&pinners);
+ Bitboard b = squares_between(s, ksq) & occupied_squares();
- Square ksq = king_square(opposite_color(c));
- return hidden_checks<ROOK, false>(c, ksq) | hidden_checks<BISHOP, false>(c, ksq);
+ assert(b);
+
+ if ( !(b & (b - 1)) // Only one bit set?
+ && (b & pieces_of_color(c))) // Is an our piece?
+ result |= b;
+ }
+ return result;
}
-/// Position:hidden_checks<>() returns a bitboard of all pinned (against the
-/// king) pieces for the given color and for the given pinner type. Or, when
-/// template parameter FindPinned is false, the pinned pieces of opposite color
-/// that are, indeed, the pieces candidate for a discovery check.
-template<PieceType Piece, bool FindPinned>
-Bitboard Position::hidden_checks(Color c, Square ksq) const {
+/// Position:pinned_pieces() returns a bitboard of all pinned (against the
+/// king) pieces for the given color.
- Square s;
- Bitboard sliders, result = EmptyBoardBB;
+Bitboard Position::pinned_pieces(Color c) const {
- if (Piece == ROOK) // Resolved at compile time
- sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq];
- else
- sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq];
+ return hidden_checkers<true>(c);
+}
- if (sliders && (!FindPinned || (sliders & ~checkersBB)))
- {
- // King blockers are candidate pinned pieces
- Bitboard candidate_pinned = piece_attacks<Piece>(ksq) & pieces_of_color(c);
- // Pinners are sliders, not checkers, that give check when
- // candidate pinned are removed.
- Bitboard pinners = (FindPinned ? sliders & ~checkersBB : sliders);
+/// Position:discovered_check_candidates() returns a bitboard containing all
+/// pieces for the given side which are candidates for giving a discovered
+/// check.
- if (Piece == ROOK)
- pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned);
- else
- pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned);
+Bitboard Position::discovered_check_candidates(Color c) const {
- // Finally for each pinner find the corresponding pinned piece (if same color of king)
- // or discovery checker (if opposite color) among the candidates.
- while (pinners)
- {
- s = pop_1st_bit(&pinners);
- result |= (squares_between(s, ksq) & candidate_pinned);
- }
- }
- return result;
+ return hidden_checkers<false>(c);
}
-
/// Position::attacks_to() computes a bitboard containing all pieces which
-/// attacks a given square. There are two versions of this function: One
-/// which finds attackers of both colors, and one which only finds the
-/// attackers for one side.
+/// attacks a given square.
Bitboard Position::attacks_to(Square s) const {
/// Position::piece_attacks_square() tests whether the piece on square f
/// attacks square t.
-bool Position::piece_attacks_square(Square f, Square t) const {
+bool Position::piece_attacks_square(Piece p, Square f, Square t) const {
assert(square_is_ok(f));
assert(square_is_ok(t));
- switch (piece_on(f))
+ switch (p)
{
case WP: return pawn_attacks_square(WHITE, f, t);
case BP: return pawn_attacks_square(BLACK, f, t);
/// Position::move_attacks_square() tests whether a move from the current
-/// position attacks a given square. Only attacks by the moving piece are
-/// considered; the function does not handle X-ray attacks.
+/// position attacks a given square.
bool Position::move_attacks_square(Move m, Square s) const {
assert(square_is_occupied(f));
- switch (piece_on(f))
- {
- case WP: return pawn_attacks_square(WHITE, t, s);
- case BP: return pawn_attacks_square(BLACK, t, s);
- case WN: case BN: return piece_attacks_square<KNIGHT>(t, s);
- case WB: case BB: return piece_attacks_square<BISHOP>(t, s);
- case WR: case BR: return piece_attacks_square<ROOK>(t, s);
- case WQ: case BQ: return piece_attacks_square<QUEEN>(t, s);
- case WK: case BK: return piece_attacks_square<KING>(t, s);
- default: break;
- }
- return false;
+ if (piece_attacks_square(piece_on(f), t, s))
+ return true;
+
+ // Move the piece and scan for X-ray attacks behind it
+ Bitboard occ = occupied_squares();
+ Color us = color_of_piece_on(f);
+ clear_bit(&occ, f);
+ set_bit(&occ, t);
+ Bitboard xray = ( (rook_attacks_bb(s, occ) & rooks_and_queens())
+ |(bishop_attacks_bb(s, occ) & bishops_and_queens())) & pieces_of_color(us);
+
+ // If we have attacks we need to verify that are caused by our move
+ // and are not already existent ones.
+ return xray && (xray ^ (xray & piece_attacks<QUEEN>(s)));
}
/// Position::find_checkers() computes the checkersBB bitboard, which
-/// contains a nonzero bit for each checking piece (0, 1 or 2). It
+/// contains a nonzero bit for each checking piece (0, 1 or 2). It
/// currently works by calling Position::attacks_to, which is probably
/// inefficient. Consider rewriting this function to use the last move
/// played, like in non-bitboard versions of Glaurung.
void Position::find_checkers() {
Color us = side_to_move();
- checkersBB = attacks_to(king_square(us), opposite_color(us));
+ st->checkersBB = attacks_to(king_square(us), opposite_color(us));
}
-/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal.
-/// There are two versions of this function: One which takes only a
-/// move as input, and one which takes a move and a bitboard of pinned
-/// pieces. The latter function is faster, and should always be preferred
-/// when a pinned piece bitboard has already been computed.
+/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
-bool Position::pl_move_is_legal(Move m) const {
+bool Position::pl_move_is_legal(Move m) const {
- return pl_move_is_legal(m, pinned_pieces(side_to_move()));
+ // If we're in check, all pseudo-legal moves are legal, because our
+ // check evasion generator only generates true legal moves.
+ return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move()));
}
bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
assert(is_ok());
assert(move_is_ok(m));
assert(pinned == pinned_pieces(side_to_move()));
-
- // If we're in check, all pseudo-legal moves are legal, because our
- // check evasion generator only generates true legal moves.
- if (is_check())
- return true;
+ assert(!is_check());
// Castling moves are checked for legality during move generation.
if (move_is_castle(m))
return true;
Color us = side_to_move();
- Color them = opposite_color(us);
Square from = move_from(m);
Square ksq = king_square(us);
assert(color_of_piece_on(from) == us);
- assert(piece_on(ksq) == king_of_color(us));
+ assert(piece_on(ksq) == piece_of_color_and_type(us, KING));
// En passant captures are a tricky special case. Because they are
// rather uncommon, we do it simply by testing whether the king is attacked
// after the move is made
if (move_is_ep(m))
{
+ Color them = opposite_color(us);
Square to = move_to(m);
Square capsq = make_square(square_file(to), square_rank(from));
Bitboard b = occupied_squares();
assert(to == ep_square());
- assert(piece_on(from) == pawn_of_color(us));
- assert(piece_on(capsq) == pawn_of_color(them));
+ assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
+ assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
assert(piece_on(to) == EMPTY);
clear_bit(&b, from);
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent.
if (from == ksq)
- return !(square_is_attacked(move_to(m), them));
+ return !(square_is_attacked(move_to(m), opposite_color(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 ( !bit_is_set(pinned, from)
+ return ( !pinned
+ || !bit_is_set(pinned, from)
|| (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq)));
}
-/// Position::move_is_check() tests whether a pseudo-legal move is a check.
-/// There are two versions of this function: One which takes only a move as
-/// input, and one which takes a move and a bitboard of discovered check
-/// candidates. The latter function is faster, and should always be preferred
-/// when a discovered check candidates bitboard has already been computed.
+/// Position::move_is_check() tests whether a pseudo-legal move is a check
bool Position::move_is_check(Move m) const {
Square ksq = king_square(them);
assert(color_of_piece_on(from) == us);
- assert(piece_on(ksq) == king_of_color(them));
+ assert(piece_on(ksq) == piece_of_color_and_type(them, KING));
// Proceed according to the type of the moving piece
switch (type_of_piece_on(from))
if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check?
return true;
- if ( bit_is_set(dcCandidates, from) // Discovered check?
+ if ( dcCandidates // Discovered check?
+ && bit_is_set(dcCandidates, from)
&& (direction_between_squares(from, ksq) != direction_between_squares(to, ksq)))
return true;
}
return false;
+ // Test discovered check and normal check according to piece type
case KNIGHT:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<KNIGHT>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || bit_is_set(piece_attacks<KNIGHT>(ksq), to);
case BISHOP:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<BISHOP>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks<BISHOP>(ksq), to));
case ROOK:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<ROOK>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || (direction_is_straight(ksq, to) && bit_is_set(piece_attacks<ROOK>(ksq), to));
case QUEEN:
// Discovered checks are impossible!
assert(!bit_is_set(dcCandidates, from));
- return bit_is_set(piece_attacks<QUEEN>(ksq), to); // Normal check?
+ return ( (direction_is_straight(ksq, to) && bit_is_set(piece_attacks<ROOK>(ksq), to))
+ || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks<BISHOP>(ksq), to)));
case KING:
// Discovered check?
}
-/// Position::move_is_capture() tests whether a move from the current
-/// position is a capture. Move must not be MOVE_NONE.
-
-bool Position::move_is_capture(Move m) const {
-
- assert(m != MOVE_NONE);
-
- return ( !square_is_empty(move_to(m))
- && (color_of_piece_on(move_to(m)) != color_of_piece_on(move_from(m)))
- )
- || move_is_ep(m);
-}
-
-
-/// Position::backup() is called when making a move. All information
-/// necessary to restore the position when the move is later unmade
-/// is saved to an UndoInfo object. The function Position::restore
-/// does the reverse operation: When one does a backup followed by
-/// a restore with the same UndoInfo object, the position is restored
-/// to the state before backup was called.
-
-void Position::backup(UndoInfo& u) const {
-
- u.castleRights = castleRights;
- u.epSquare = epSquare;
- u.checkersBB = checkersBB;
- u.key = key;
- u.pawnKey = pawnKey;
- u.materialKey = materialKey;
- u.rule50 = rule50;
- u.lastMove = lastMove;
- u.mgValue = mgValue;
- u.egValue = egValue;
- u.capture = NO_PIECE_TYPE;
-}
-
-
-/// Position::restore() is called when unmaking a move. It copies back
-/// the information backed up during a previous call to Position::backup.
-
-void Position::restore(const UndoInfo& u) {
-
- castleRights = u.castleRights;
- epSquare = u.epSquare;
- checkersBB = u.checkersBB;
- key = u.key;
- pawnKey = u.pawnKey;
- materialKey = u.materialKey;
- rule50 = u.rule50;
- lastMove = u.lastMove;
- mgValue = u.mgValue;
- egValue = u.egValue;
- // u.capture is restored in undo_move()
-}
-
-
-/// Position::update_checkers() is a private method to udpate chekers info
+/// Position::update_checkers() udpates chekers info given the move. It is called
+/// in do_move() and is faster then find_checkers().
template<PieceType Piece>
inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from,
Square to, Bitboard dcCandidates) {
- if (Piece != KING && bit_is_set(piece_attacks<Piece>(ksq), to))
+ const bool Bishop = (Piece == QUEEN || Piece == BISHOP);
+ const bool Rook = (Piece == QUEEN || Piece == ROOK);
+ const bool Slider = Bishop || Rook;
+
+ // Direct checks
+ if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to))
+ || (Rook && bit_is_set(RookPseudoAttacks[ksq], to)))
+ && bit_is_set(piece_attacks<Piece>(ksq), to)) // slow, try to early skip
set_bit(pCheckersBB, to);
+ else if ( Piece != KING
+ && !Slider
+ && bit_is_set(piece_attacks<Piece>(ksq), to))
+ set_bit(pCheckersBB, to);
+
+ // Discovery checks
if (Piece != QUEEN && bit_is_set(dcCandidates, from))
{
if (Piece != ROOK)
}
-/// Position::do_move() makes a move, and backs up all information necessary
-/// to undo the move to an UndoInfo object. The move is assumed to be legal.
+/// Position::do_move() makes a move, and saves all information necessary
+/// to a StateInfo object. The move is assumed to be legal.
/// Pseudo-legal moves should be filtered out before this function is called.
-/// There are two versions of this function, one which takes only the move and
-/// the UndoInfo as input, and one which takes a third parameter, a bitboard of
-/// discovered check candidates. The second version is faster, because knowing
-/// the discovered check candidates makes it easier to update the checkersBB
-/// member variable in the position object.
-void Position::do_move(Move m, UndoInfo& u) {
+void Position::do_move(Move m, StateInfo& newSt) {
- do_move(m, u, discovered_check_candidates(side_to_move()));
+ do_move(m, newSt, discovered_check_candidates(side_to_move()));
}
-void Position::do_move(Move m, UndoInfo& u, Bitboard dcCandidates) {
+void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
assert(is_ok());
assert(move_is_ok(m));
- // Back up the necessary information to our UndoInfo object (except the
- // captured piece, which is taken care of later.
- backup(u);
+ // Copy some fields of old state to our new StateInfo object except the
+ // ones which are recalculated from scratch anyway, then switch our state
+ // pointer to point to the new, ready to be updated, state.
+ struct ReducedStateInfo {
+ Key key, pawnKey, materialKey;
+ int castleRights, rule50;
+ Square epSquare;
+ Value mgValue, egValue;
+ Value npMaterial[2];
+ };
+
+ memcpy(&newSt, st, sizeof(ReducedStateInfo));
+ newSt.capture = NO_PIECE_TYPE;
+ newSt.previous = st;
+ st = &newSt;
// Save the current key to the history[] array, in order to be able to
// detect repetition draws.
- history[gamePly] = key;
+ history[gamePly] = st->key;
// Increment the 50 moves rule draw counter. Resetting it to zero in the
// case of non-reversible moves is taken care of later.
- rule50++;
+ st->rule50++;
if (move_is_castle(m))
do_castle_move(m);
else if (move_promotion(m))
- do_promotion_move(m, u);
+ do_promotion_move(m);
else if (move_is_ep(m))
do_ep_move(m);
else
assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY);
PieceType piece = type_of_piece_on(from);
- PieceType capture = type_of_piece_on(to);
- if (capture)
- {
- u.capture = capture;
- do_capture_move(m, capture, them, to);
- }
+ st->capture = type_of_piece_on(to);
+
+ if (st->capture)
+ do_capture_move(st->capture, them, to);
// Move the piece
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[piece]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[piece]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+ Bitboard move_bb = make_move_bb(from, to);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[piece]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
+
board[to] = board[from];
board[from] = EMPTY;
// Update hash key
- key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to];
+ st->key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to];
// Update incremental scores
- mgValue -= mg_pst(us, piece, from);
- mgValue += mg_pst(us, piece, to);
- egValue -= eg_pst(us, piece, from);
- egValue += eg_pst(us, piece, to);
+ st->mgValue -= pst<MidGame>(us, piece, from);
+ st->mgValue += pst<MidGame>(us, piece, to);
+ st->egValue -= pst<EndGame>(us, piece, from);
+ st->egValue += pst<EndGame>(us, piece, to);
// If the moving piece was a king, update the king square
if (piece == KING)
kingSquare[us] = to;
// Reset en passant square
- if (epSquare != SQ_NONE)
+ if (st->epSquare != SQ_NONE)
{
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
+ st->key ^= zobEp[st->epSquare];
+ st->epSquare = SQ_NONE;
}
// If the moving piece was a pawn do some special extra work
if (piece == PAWN)
{
// Reset rule 50 draw counter
- rule50 = 0;
+ st->rule50 = 0;
// Update pawn hash key
- pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+ st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
// Set en passant square, only if moved pawn can be captured
if (abs(int(to) - int(from)) == 16)
if ( (us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK)))
|| (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE))))
{
- epSquare = Square((int(from) + int(to)) / 2);
- key ^= zobEp[epSquare];
+ st->epSquare = Square((int(from) + int(to)) / 2);
+ st->key ^= zobEp[st->epSquare];
}
}
}
index[to] = index[from];
// Update castle rights
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[from];
- castleRights &= castleRightsMask[to];
- key ^= zobCastle[castleRights];
+ st->key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[from];
+ st->castleRights &= castleRightsMask[to];
+ st->key ^= zobCastle[st->castleRights];
// Update checkers bitboard, piece must be already moved
- checkersBB = EmptyBoardBB;
+ st->checkersBB = EmptyBoardBB;
Square ksq = king_square(them);
switch (piece)
{
- case PAWN: update_checkers<PAWN>(&checkersBB, ksq, from, to, dcCandidates); break;
- case KNIGHT: update_checkers<KNIGHT>(&checkersBB, ksq, from, to, dcCandidates); break;
- case BISHOP: update_checkers<BISHOP>(&checkersBB, ksq, from, to, dcCandidates); break;
- case ROOK: update_checkers<ROOK>(&checkersBB, ksq, from, to, dcCandidates); break;
- case QUEEN: update_checkers<QUEEN>(&checkersBB, ksq, from, to, dcCandidates); break;
- case KING: update_checkers<KING>(&checkersBB, ksq, from, to, dcCandidates); break;
+ case PAWN: update_checkers<PAWN>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case KNIGHT: update_checkers<KNIGHT>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case BISHOP: update_checkers<BISHOP>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case ROOK: update_checkers<ROOK>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case QUEEN: update_checkers<QUEEN>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case KING: update_checkers<KING>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
default: assert(false); break;
}
}
// Finish
- key ^= zobSideToMove;
+ st->key ^= zobSideToMove;
sideToMove = opposite_color(sideToMove);
gamePly++;
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
+ st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
assert(is_ok());
}
/// Position::do_capture_move() is a private method used to update captured
/// piece info. It is called from the main Position::do_move function.
-void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) {
+void Position::do_capture_move(PieceType capture, Color them, Square to) {
assert(capture != KING);
// Remove captured piece
clear_bit(&(byColorBB[them]), to);
clear_bit(&(byTypeBB[capture]), to);
+ clear_bit(&(byTypeBB[0]), to);
// Update hash key
- key ^= zobrist[them][capture][to];
+ st->key ^= zobrist[them][capture][to];
// If the captured piece was a pawn, update pawn hash key
if (capture == PAWN)
- pawnKey ^= zobrist[them][PAWN][to];
+ st->pawnKey ^= zobrist[them][PAWN][to];
// Update incremental scores
- mgValue -= mg_pst(them, capture, to);
- egValue -= eg_pst(them, capture, to);
-
- assert(!move_promotion(m) || capture != PAWN);
+ st->mgValue -= pst<MidGame>(them, capture, to);
+ st->egValue -= pst<EndGame>(them, capture, to);
// Update material
if (capture != PAWN)
- npMaterial[them] -= piece_value_midgame(capture);
+ st->npMaterial[them] -= piece_value_midgame(capture);
// Update material hash key
- materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
+ st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
// Update piece count
pieceCount[them][capture]--;
index[pieceList[them][capture][index[to]]] = index[to];
// Reset rule 50 counter
- rule50 = 0;
+ st->rule50 = 0;
}
Square rfrom = move_to(m); // HACK: See comment at beginning of function
Square kto, rto;
- assert(piece_on(kfrom) == king_of_color(us));
- assert(piece_on(rfrom) == rook_of_color(us));
+ assert(piece_on(kfrom) == piece_of_color_and_type(us, KING));
+ assert(piece_on(rfrom) == piece_of_color_and_type(us, ROOK));
// Find destination squares for king and rook
if (rfrom > kfrom) // O-O
// Update board array
board[kfrom] = board[rfrom] = EMPTY;
- board[kto] = king_of_color(us);
- board[rto] = rook_of_color(us);
+ board[kto] = piece_of_color_and_type(us, KING);
+ board[rto] = piece_of_color_and_type(us, ROOK);
// Update king square
kingSquare[us] = kto;
index[rto] = tmp;
// Update incremental scores
- mgValue -= mg_pst(us, KING, kfrom);
- mgValue += mg_pst(us, KING, kto);
- egValue -= eg_pst(us, KING, kfrom);
- egValue += eg_pst(us, KING, kto);
- mgValue -= mg_pst(us, ROOK, rfrom);
- mgValue += mg_pst(us, ROOK, rto);
- egValue -= eg_pst(us, ROOK, rfrom);
- egValue += eg_pst(us, ROOK, rto);
+ st->mgValue -= pst<MidGame>(us, KING, kfrom);
+ st->mgValue += pst<MidGame>(us, KING, kto);
+ st->egValue -= pst<EndGame>(us, KING, kfrom);
+ st->egValue += pst<EndGame>(us, KING, kto);
+ st->mgValue -= pst<MidGame>(us, ROOK, rfrom);
+ st->mgValue += pst<MidGame>(us, ROOK, rto);
+ st->egValue -= pst<EndGame>(us, ROOK, rfrom);
+ st->egValue += pst<EndGame>(us, ROOK, rto);
// Update hash key
- key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
+ st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
+ st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
// Clear en passant square
- if (epSquare != SQ_NONE)
+ if (st->epSquare != SQ_NONE)
{
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
+ st->key ^= zobEp[st->epSquare];
+ st->epSquare = SQ_NONE;
}
// Update castling rights
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[kfrom];
- key ^= zobCastle[castleRights];
+ st->key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[kfrom];
+ st->key ^= zobCastle[st->castleRights];
// Reset rule 50 counter
- rule50 = 0;
+ st->rule50 = 0;
// Update checkers BB
- checkersBB = attacks_to(king_square(them), us);
+ st->checkersBB = attacks_to(king_square(them), us);
}
/// Position::do_promotion_move() is a private method used to make a promotion
-/// move. It is called from the main Position::do_move function. The
-/// UndoInfo object, which has been initialized in Position::do_move, is
-/// used to store the captured piece (if any).
+/// move. It is called from the main Position::do_move function.
-void Position::do_promotion_move(Move m, UndoInfo &u) {
+void Position::do_promotion_move(Move m) {
Color us, them;
Square from, to;
- PieceType capture, promotion;
+ PieceType promotion;
assert(is_ok());
assert(move_is_ok(m));
to = move_to(m);
assert(relative_rank(us, to) == RANK_8);
- assert(piece_on(from) == pawn_of_color(us));
+ assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
assert(color_of_piece_on(to) == them || square_is_empty(to));
- capture = type_of_piece_on(to);
+ st->capture = type_of_piece_on(to);
- if (capture)
- {
- u.capture = capture;
- do_capture_move(m, capture, them, to);
- }
+ if (st->capture)
+ do_capture_move(st->capture, them, to);
// Remove pawn
clear_bit(&(byColorBB[us]), from);
board[to] = piece_of_color_and_type(us, promotion);
// Update hash key
- key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to];
+ st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to];
// Update pawn hash key
- pawnKey ^= zobrist[us][PAWN][from];
+ st->pawnKey ^= zobrist[us][PAWN][from];
// Update material key
- materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]];
- materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1];
+ st->materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]];
+ st->materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1];
// Update piece counts
pieceCount[us][PAWN]--;
index[to] = pieceCount[us][promotion] - 1;
// Update incremental scores
- mgValue -= mg_pst(us, PAWN, from);
- mgValue += mg_pst(us, promotion, to);
- egValue -= eg_pst(us, PAWN, from);
- egValue += eg_pst(us, promotion, to);
+ st->mgValue -= pst<MidGame>(us, PAWN, from);
+ st->mgValue += pst<MidGame>(us, promotion, to);
+ st->egValue -= pst<EndGame>(us, PAWN, from);
+ st->egValue += pst<EndGame>(us, promotion, to);
// Update material
- npMaterial[us] += piece_value_midgame(promotion);
+ st->npMaterial[us] += piece_value_midgame(promotion);
// Clear the en passant square
- if (epSquare != SQ_NONE)
+ if (st->epSquare != SQ_NONE)
{
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
+ st->key ^= zobEp[st->epSquare];
+ st->epSquare = SQ_NONE;
}
// Update castle rights
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[to];
- key ^= zobCastle[castleRights];
+ st->key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[to];
+ st->key ^= zobCastle[st->castleRights];
// Reset rule 50 counter
- rule50 = 0;
+ st->rule50 = 0;
// Update checkers BB
- checkersBB = attacks_to(king_square(them), us);
+ st->checkersBB = attacks_to(king_square(them), us);
}
/// Position::do_ep_move() is a private method used to make an en passant
-/// capture. It is called from the main Position::do_move function. Because
-/// the captured piece is always a pawn, we don't need to pass an UndoInfo
-/// object in which to store the captured piece.
+/// capture. It is called from the main Position::do_move function.
void Position::do_ep_move(Move m) {
to = move_to(m);
capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
- assert(to == epSquare);
+ assert(to == st->epSquare);
assert(relative_rank(us, to) == RANK_6);
assert(piece_on(to) == EMPTY);
- assert(piece_on(from) == pawn_of_color(us));
- assert(piece_on(capsq) == pawn_of_color(them));
+ assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
+ assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
- // Remove captured piece
+ // Remove captured pawn
clear_bit(&(byColorBB[them]), capsq);
clear_bit(&(byTypeBB[PAWN]), capsq);
clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares
board[capsq] = EMPTY;
- // Remove moving piece from source square
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[PAWN]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
-
- // Put moving piece on destination square
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[PAWN]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+ // Move capturing pawn
+ Bitboard move_bb = make_move_bb(from, to);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[PAWN]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
board[to] = board[from];
board[from] = EMPTY;
// Update material hash key
- materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]];
+ st->materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]];
// Update piece count
pieceCount[them][PAWN]--;
index[pieceList[them][PAWN][index[capsq]]] = index[capsq];
// Update hash key
- key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- key ^= zobrist[them][PAWN][capsq];
- key ^= zobEp[epSquare];
+ st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+ st->key ^= zobrist[them][PAWN][capsq];
+ st->key ^= zobEp[st->epSquare];
// Update pawn hash key
- pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- pawnKey ^= zobrist[them][PAWN][capsq];
+ st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+ st->pawnKey ^= zobrist[them][PAWN][capsq];
// Update incremental scores
- mgValue -= mg_pst(them, PAWN, capsq);
- mgValue -= mg_pst(us, PAWN, from);
- mgValue += mg_pst(us, PAWN, to);
- egValue -= eg_pst(them, PAWN, capsq);
- egValue -= eg_pst(us, PAWN, from);
- egValue += eg_pst(us, PAWN, to);
+ st->mgValue -= pst<MidGame>(them, PAWN, capsq);
+ st->mgValue -= pst<MidGame>(us, PAWN, from);
+ st->mgValue += pst<MidGame>(us, PAWN, to);
+ st->egValue -= pst<EndGame>(them, PAWN, capsq);
+ st->egValue -= pst<EndGame>(us, PAWN, from);
+ st->egValue += pst<EndGame>(us, PAWN, to);
// Reset en passant square
- epSquare = SQ_NONE;
+ st->epSquare = SQ_NONE;
// Reset rule 50 counter
- rule50 = 0;
+ st->rule50 = 0;
// Update checkers BB
- checkersBB = attacks_to(king_square(them), us);
+ st->checkersBB = attacks_to(king_square(them), us);
}
/// Position::undo_move() unmakes a move. When it returns, the position should
-/// be restored to exactly the same state as before the move was made. It is
-/// important that Position::undo_move is called with the same move and UndoInfo
-/// object as the earlier call to Position::do_move.
+/// be restored to exactly the same state as before the move was made.
-void Position::undo_move(Move m, const UndoInfo &u) {
+void Position::undo_move(Move m) {
assert(is_ok());
assert(move_is_ok(m));
gamePly--;
sideToMove = opposite_color(sideToMove);
- // Restore information from our UndoInfo object (except the captured piece,
- // which is taken care of later)
- restore(u);
-
if (move_is_castle(m))
undo_castle_move(m);
else if (move_promotion(m))
- undo_promotion_move(m, u);
+ undo_promotion_move(m);
else if (move_is_ep(m))
undo_ep_move(m);
else
{
Color us, them;
Square from, to;
- PieceType piece, capture;
+ PieceType piece;
us = side_to_move();
them = opposite_color(us);
assert(color_of_piece_on(to) == us);
// Put the piece back at the source square
+ Bitboard move_bb = make_move_bb(to, from);
piece = type_of_piece_on(to);
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[piece]), from);
- set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[piece]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
board[from] = piece_of_color_and_type(us, piece);
- // Clear the destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[piece]), to);
- clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
-
// If the moving piece was a king, update the king square
if (piece == KING)
kingSquare[us] = from;
pieceList[us][piece][index[to]] = from;
index[from] = index[to];
- capture = u.capture;
-
- if (capture)
+ if (st->capture)
{
- assert(capture != KING);
+ assert(st->capture != KING);
- // Replace the captured piece
+ // Restore the captured piece
set_bit(&(byColorBB[them]), to);
- set_bit(&(byTypeBB[capture]), to);
+ set_bit(&(byTypeBB[st->capture]), to);
set_bit(&(byTypeBB[0]), to);
- board[to] = piece_of_color_and_type(them, capture);
-
- // Update material
- if (capture != PAWN)
- npMaterial[them] += piece_value_midgame(capture);
+ board[to] = piece_of_color_and_type(them, st->capture);
// Update piece list
- pieceList[them][capture][pieceCount[them][capture]] = to;
- index[to] = pieceCount[them][capture];
+ pieceList[them][st->capture][pieceCount[them][st->capture]] = to;
+ index[to] = pieceCount[them][st->capture];
// Update piece count
- pieceCount[them][capture]++;
+ pieceCount[them][st->capture]++;
} else
board[to] = EMPTY;
}
+ // Finally point our state pointer back to the previous state
+ st = st->previous;
+
assert(is_ok());
}
rto = relative_square(us, SQ_D1);
}
- assert(piece_on(kto) == king_of_color(us));
- assert(piece_on(rto) == rook_of_color(us));
+ assert(piece_on(kto) == piece_of_color_and_type(us, KING));
+ assert(piece_on(rto) == piece_of_color_and_type(us, ROOK));
// Remove pieces from destination squares
clear_bit(&(byColorBB[us]), kto);
// Update board
board[rto] = board[kto] = EMPTY;
- board[rfrom] = rook_of_color(us);
- board[kfrom] = king_of_color(us);
+ board[rfrom] = piece_of_color_and_type(us, ROOK);
+ board[kfrom] = piece_of_color_and_type(us, KING);
// Update king square
kingSquare[us] = kfrom;
/// Position::undo_promotion_move() is a private method used to unmake a
/// promotion move. It is called from the main Position::do_move
-/// function. The UndoInfo object, which has been initialized in
-/// Position::do_move, is used to put back the captured piece (if any).
+/// function.
-void Position::undo_promotion_move(Move m, const UndoInfo &u) {
+void Position::undo_promotion_move(Move m) {
Color us, them;
Square from, to;
- PieceType capture, promotion;
+ PieceType promotion;
assert(move_is_ok(m));
assert(move_promotion(m));
set_bit(&(byColorBB[us]), from);
set_bit(&(byTypeBB[PAWN]), from);
set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- board[from] = pawn_of_color(us);
-
- // Update material
- npMaterial[us] -= piece_value_midgame(promotion);
+ board[from] = piece_of_color_and_type(us, PAWN);
// Update piece list
pieceList[us][PAWN][pieceCount[us][PAWN]] = from;
pieceCount[us][promotion]--;
pieceCount[us][PAWN]++;
- capture = u.capture;
-
- if (capture)
+ if (st->capture)
{
- assert(capture != KING);
+ assert(st->capture != KING);
// Insert captured piece:
set_bit(&(byColorBB[them]), to);
- set_bit(&(byTypeBB[capture]), to);
+ set_bit(&(byTypeBB[st->capture]), to);
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = piece_of_color_and_type(them, capture);
-
- // Update material. Because the move is a promotion move, we know
- // that the captured piece cannot be a pawn.
- assert(capture != PAWN);
- npMaterial[them] += piece_value_midgame(capture);
+ board[to] = piece_of_color_and_type(them, st->capture);
// Update piece list
- pieceList[them][capture][pieceCount[them][capture]] = to;
- index[to] = pieceCount[them][capture];
+ pieceList[them][st->capture][pieceCount[them][st->capture]] = to;
+ index[to] = pieceCount[them][st->capture];
// Update piece count
- pieceCount[them][capture]++;
+ pieceCount[them][st->capture]++;
} else
board[to] = EMPTY;
}
/// Position::undo_ep_move() is a private method used to unmake an en passant
-/// capture. It is called from the main Position::undo_move function. Because
-/// the captured piece is always a pawn, we don't need to pass an UndoInfo
-/// object from which to retrieve the captured piece.
+/// capture. It is called from the main Position::undo_move function.
void Position::undo_ep_move(Move m) {
Square to = move_to(m);
Square capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
- assert(to == ep_square());
+ assert(to == st->previous->epSquare);
assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(to) == pawn_of_color(us));
+ assert(piece_on(to) == piece_of_color_and_type(us, PAWN));
assert(piece_on(from) == EMPTY);
assert(piece_on(capsq) == EMPTY);
- // Replace captured piece
+ // Restore captured pawn
set_bit(&(byColorBB[them]), capsq);
set_bit(&(byTypeBB[PAWN]), capsq);
set_bit(&(byTypeBB[0]), capsq);
- board[capsq] = pawn_of_color(them);
+ board[capsq] = piece_of_color_and_type(them, PAWN);
- // Remove moving piece from destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[PAWN]), to);
- clear_bit(&(byTypeBB[0]), to);
+ // Move capturing pawn back to source square
+ Bitboard move_bb = make_move_bb(to, from);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[PAWN]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb);
board[to] = EMPTY;
+ board[from] = piece_of_color_and_type(us, PAWN);
- // Replace moving piece at source square
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[PAWN]), from);
- set_bit(&(byTypeBB[0]), from);
- board[from] = pawn_of_color(us);
-
- // Update piece list:
+ // Update piece list
pieceList[us][PAWN][index[to]] = from;
index[from] = index[to];
pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq;
index[capsq] = pieceCount[them][PAWN];
- // Update piece count:
+ // Update piece count
pieceCount[them][PAWN]++;
}
/// Position::do_null_move makes() a "null move": It switches the side to move
/// and updates the hash key without executing any move on the board.
-void Position::do_null_move(UndoInfo& u) {
+void Position::do_null_move(StateInfo& backupSt) {
assert(is_ok());
assert(!is_check());
// Back up the information necessary to undo the null move to the supplied
- // UndoInfo object. In the case of a null move, the only thing we need to
- // remember is the last move made and the en passant square.
- u.lastMove = lastMove;
- u.epSquare = epSquare;
+ // StateInfo object.
+ // Note that differently from normal case here backupSt is actually used as
+ // a backup storage not as a new state to be used.
+ backupSt.epSquare = st->epSquare;
+ backupSt.key = st->key;
+ backupSt.mgValue = st->mgValue;
+ backupSt.egValue = st->egValue;
+ backupSt.previous = st->previous;
+ st->previous = &backupSt;
// Save the current key to the history[] array, in order to be able to
// detect repetition draws.
- history[gamePly] = key;
+ history[gamePly] = st->key;
// Update the necessary information
sideToMove = opposite_color(sideToMove);
- if (epSquare != SQ_NONE)
- key ^= zobEp[epSquare];
+ if (st->epSquare != SQ_NONE)
+ st->key ^= zobEp[st->epSquare];
- epSquare = SQ_NONE;
- rule50++;
+ st->epSquare = SQ_NONE;
+ st->rule50++;
gamePly++;
- key ^= zobSideToMove;
+ st->key ^= zobSideToMove;
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
+ st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
assert(is_ok());
}
/// Position::undo_null_move() unmakes a "null move".
-void Position::undo_null_move(const UndoInfo &u) {
+void Position::undo_null_move() {
assert(is_ok());
assert(!is_check());
- // Restore information from the supplied UndoInfo object:
- lastMove = u.lastMove;
- epSquare = u.epSquare;
- if (epSquare != SQ_NONE)
- key ^= zobEp[epSquare];
+ // Restore information from the our backup StateInfo object
+ st->epSquare = st->previous->epSquare;
+ st->key = st->previous->key;
+ st->mgValue = st->previous->mgValue;
+ st->egValue = st->previous->egValue;
+ st->previous = st->previous->previous;
- // Update the necessary information.
+ // Update the necessary information
sideToMove = opposite_color(sideToMove);
- rule50--;
+ st->rule50--;
gamePly--;
- key ^= zobSideToMove;
-
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
assert(is_ok());
}
/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are three versions of
+/// material gain or loss resulting from a move. There are three versions of
/// this function: One which takes a destination square as input, one takes a
/// move, and one which takes a 'from' and a 'to' square. The function does
/// not yet understand promotions captures.
0, 0
};
- Bitboard attackers, occ, b;
+ Bitboard attackers, stmAttackers, occ, b;
assert(square_is_ok(from) || from == SQ_NONE);
assert(square_is_ok(to));
occ = occupied_squares();
// Handle en passant moves
- if (epSquare == to && type_of_piece_on(from) == PAWN)
+ if (st->epSquare == to && type_of_piece_on(from) == PAWN)
{
assert(capture == EMPTY);
Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S);
capture = piece_on(capQq);
-
assert(type_of_piece_on(capQq) == PAWN);
// Remove the captured pawn
}
// If the opponent has no attackers we are finished
- if ((attackers & pieces_of_color(them)) == EmptyBoardBB)
+ stmAttackers = attackers & pieces_of_color(them);
+ if (!stmAttackers)
return seeValues[capture];
attackers &= occ; // Remove the moving piece
swapList[0] = seeValues[capture];
do {
- // Locate the least valuable attacker for the side to move. The loop
+ // Locate the least valuable attacker for the side to move. The loop
// below looks like it is potentially infinite, but it isn't. We know
// that the side to move still has at least one attacker left.
- for (pt = PAWN; !(attackers & pieces_of_color_and_type(c, pt)); pt++)
+ for (pt = PAWN; !(stmAttackers & pieces_of_type(pt)); pt++)
assert(pt < KING);
// Remove the attacker we just found from the 'attackers' bitboard,
// and scan for new X-ray attacks behind the attacker.
- b = attackers & pieces_of_color_and_type(c, pt);
- occ ^= (b & -b);
+ b = stmAttackers & pieces_of_type(pt);
+ occ ^= (b & (~b + 1));
attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens())
| (bishop_attacks_bb(to, occ) & bishops_and_queens());
// before beginning the next iteration
lastCapturingPieceValue = seeValues[pt];
c = opposite_color(c);
+ stmAttackers = attackers & pieces_of_color(c);
// Stop after a king capture
- if (pt == KING && (attackers & pieces_of_color(c)))
+ if (pt == KING && stmAttackers)
{
assert(n < 32);
swapList[n++] = 100;
break;
}
- } while (attackers & pieces_of_color(c));
+ } 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
}
+/// Position::saveState() copies the content of the current state
+/// inside startState and makes st point to it. This is needed
+/// when the st pointee could become stale, as example because
+/// the caller is about to going out of scope.
+
+void Position::saveState() {
+
+ startState = *st;
+ st = &startState;
+ st->previous = NULL; // as a safe guard
+}
+
+
/// Position::clear() erases the position object to a pristine state, with an
/// empty board, white to move, and no castling rights.
void Position::clear() {
+ st = &startState;
+ memset(st, 0, sizeof(StateInfo));
+ st->epSquare = SQ_NONE;
+
+ memset(index, 0, sizeof(int) * 64);
+ memset(byColorBB, 0, sizeof(Bitboard) * 2);
+
for (int i = 0; i < 64; i++)
- {
board[i] = EMPTY;
- index[i] = 0;
- }
-
- for (int i = 0; i < 2; i++)
- byColorBB[i] = EmptyBoardBB;
for (int i = 0; i < 7; i++)
{
pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
}
- checkersBB = EmptyBoardBB;
-
- lastMove = MOVE_NONE;
-
sideToMove = WHITE;
- castleRights = NO_CASTLES;
+ gamePly = 0;
initialKFile = FILE_E;
initialKRFile = FILE_H;
initialQRFile = FILE_A;
- epSquare = SQ_NONE;
- rule50 = 0;
- gamePly = 0;
}
void Position::allow_oo(Color c) {
- castleRights |= (1 + int(c));
+ st->castleRights |= (1 + int(c));
}
void Position::allow_ooo(Color c) {
- castleRights |= (4 + 4*int(c));
+ st->castleRights |= (4 + 4*int(c));
}
if (ep_square() != SQ_NONE)
result ^= zobEp[ep_square()];
- result ^= zobCastle[castleRights];
+ result ^= zobCastle[st->castleRights];
if (side_to_move() == BLACK)
result ^= zobSideToMove;
}
-/// Position::compute_mg_value() and Position::compute_eg_value() compute 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.
-
-Value Position::compute_mg_value() const {
+/// Position::compute_value() compute 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.
+template<Position::GamePhase Phase>
+Value Position::compute_value() const {
Value result = Value(0);
Bitboard b;
{
s = pop_1st_bit(&b);
assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += mg_pst(c, pt, s);
+ result += pst<Phase>(c, pt, s);
}
}
- result += (side_to_move() == WHITE)? TempoValueMidgame / 2 : -TempoValueMidgame / 2;
- return result;
-}
-
-Value Position::compute_eg_value() const {
-
- Value result = Value(0);
- Bitboard b;
- Square s;
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- {
- b = pieces_of_color_and_type(c, pt);
- while(b)
- {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += eg_pst(c, pt, s);
- }
- }
- result += (side_to_move() == WHITE)? TempoValueEndgame / 2 : -TempoValueEndgame / 2;
+ const Value TempoValue = (Phase == MidGame ? TempoValueMidgame : TempoValueEndgame);
+ result += (side_to_move() == WHITE)? TempoValue / 2 : -TempoValue / 2;
return result;
}
Value Position::compute_non_pawn_material(Color c) const {
Value result = Value(0);
- Square s;
for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
{
Bitboard b = pieces_of_color_and_type(c, pt);
- while(b)
+ while (b)
{
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
+ assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt));
+ pop_1st_bit(&b);
result += piece_value_midgame(pt);
}
}
}
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated. Note that this function is currently very
-/// slow, and shouldn't be used frequently inside the search.
-
-bool Position::is_mate() const {
-
- if (is_check())
- {
- MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0));
- return mp.get_next_move() == MOVE_NONE;
- }
- return false;
-}
-
-
/// Position::is_draw() tests whether the position is drawn by material,
/// repetition, or the 50 moves rule. It does not detect stalemates, this
/// must be done by the search.
return true;
// Draw by the 50 moves rule?
- if (rule50 > 100 || (rule50 == 100 && !is_check()))
+ if (st->rule50 > 100 || (st->rule50 == 100 && !is_check()))
return true;
// Draw by repetition?
- for (int i = 2; i < Min(gamePly, rule50); i += 2)
- if (history[gamePly - i] == key)
+ for (int i = 2; i < Min(gamePly, st->rule50); i += 2)
+ if (history[gamePly - i] == st->key)
return true;
return false;
}
+/// Position::is_mate() returns true or false depending on whether the
+/// side to move is checkmated.
+
+bool Position::is_mate() const {
+
+ MoveStack moves[256];
+
+ return is_check() && !generate_evasions(*this, moves, pinned_pieces(sideToMove));
+}
+
+
/// Position::has_mate_threat() tests whether a given color has a mate in one
-/// from the current position. This function is quite slow, but it doesn't
-/// matter, because it is currently only called from PV nodes, which are rare.
+/// from the current position.
bool Position::has_mate_threat(Color c) {
- UndoInfo u1, u2;
+ StateInfo st1, st2;
Color stm = side_to_move();
- // The following lines are useless and silly, but prevents gcc from
- // emitting a stupid warning stating that u1.lastMove and u1.epSquare might
- // be used uninitialized.
- u1.lastMove = lastMove;
- u1.epSquare = epSquare;
-
if (is_check())
return false;
// If the input color is not equal to the side to move, do a null move
if (c != stm)
- do_null_move(u1);
+ do_null_move(st1);
MoveStack mlist[120];
int count;
bool result = false;
+ Bitboard dc = discovered_check_candidates(sideToMove);
+ Bitboard pinned = pinned_pieces(sideToMove);
- // Generate legal moves
- count = generate_legal_moves(*this, mlist);
+ // Generate pseudo-legal non-capture and capture check moves
+ count = generate_non_capture_checks(*this, mlist, dc);
+ count += generate_captures(*this, mlist + count);
// Loop through the moves, and see if one of them is mate
for (int i = 0; i < count; i++)
{
- do_move(mlist[i].move, u2);
+ Move move = mlist[i].move;
+
+ if (!pl_move_is_legal(move, pinned))
+ continue;
+
+ do_move(move, st2);
if (is_mate())
result = true;
- undo_move(mlist[i].move, u2);
+ undo_move(move);
}
// Undo null move, if necessary
if (c != stm)
- undo_null_move(u1);
+ undo_null_move();
return result;
}
/// the white and black sides reversed. This is only useful for debugging,
/// especially for finding evaluation symmetry bugs.
-void Position::flipped_copy(const Position &pos) {
+void Position::flipped_copy(const Position& pos) {
assert(pos.is_ok());
castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
// En passant square
- if (pos.epSquare != SQ_NONE)
- epSquare = flip_square(pos.epSquare);
+ if (pos.st->epSquare != SQ_NONE)
+ st->epSquare = flip_square(pos.st->epSquare);
// Checkers
find_checkers();
// Hash keys
- key = compute_key();
- pawnKey = compute_pawn_key();
- materialKey = compute_material_key();
+ st->key = compute_key();
+ st->pawnKey = compute_pawn_key();
+ st->materialKey = compute_material_key();
// Incremental scores
- mgValue = compute_mg_value();
- egValue = compute_eg_value();
+ st->mgValue = compute_value<MidGame>();
+ st->egValue = compute_value<EndGame>();
// Material
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
+ st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
assert(is_ok());
}
// Is there more than 2 checkers?
if (failedStep) (*failedStep)++;
- if (debugCheckerCount && count_1s(checkersBB) > 2)
+ if (debugCheckerCount && count_1s(st->checkersBB) > 2)
return false;
// Bitboards OK?
// Hash key OK?
if (failedStep) (*failedStep)++;
- if (debugKey && key != compute_key())
+ if (debugKey && st->key != compute_key())
return false;
// Pawn hash key OK?
if (failedStep) (*failedStep)++;
- if (debugPawnKey && pawnKey != compute_pawn_key())
+ if (debugPawnKey && st->pawnKey != compute_pawn_key())
return false;
// Material hash key OK?
if (failedStep) (*failedStep)++;
- if (debugMaterialKey && materialKey != compute_material_key())
+ if (debugMaterialKey && st->materialKey != compute_material_key())
return false;
// Incremental eval OK?
if (failedStep) (*failedStep)++;
if (debugIncrementalEval)
{
- if (mgValue != compute_mg_value())
+ if (st->mgValue != compute_value<MidGame>())
return false;
- if (egValue != compute_eg_value())
+ if (st->egValue != compute_value<EndGame>())
return false;
}
if (failedStep) (*failedStep)++;
if (debugNonPawnMaterial)
{
- if (npMaterial[WHITE] != compute_non_pawn_material(WHITE))
+ if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
return false;
- if (npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
return false;
}
projects / stockfish / blobdiff