/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include "position.h"
+
#include <algorithm>
+#include <atomic>
#include <cassert>
-#include <cstddef> // For offsetof()
-#include <cstring> // For std::memset, std::memcmp
+#include <cctype>
+#include <cstddef>
+#include <cstring>
+#include <initializer_list>
#include <iomanip>
+#include <iostream>
#include <sstream>
+#include <string_view>
+#include <utility>
#include "bitboard.h"
#include "misc.h"
#include "movegen.h"
-#include "position.h"
+#include "nnue/nnue_common.h"
+#include "syzygy/tbprobe.h"
#include "thread.h"
#include "tt.h"
#include "uci.h"
-#include "syzygy/tbprobe.h"
using std::string;
+namespace Stockfish {
+
namespace Zobrist {
Key psq[PIECE_NB][SQUARE_NB];
Key enpassant[FILE_NB];
Key castling[CASTLING_RIGHT_NB];
- Key side, noPawns;
+ Key side;
}
namespace {
-const string PieceToChar(" PNBRQK pnbrqk");
+constexpr std::string_view PieceToChar(" PNBRQK pnbrqk");
constexpr Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING };
<< std::setfill(' ') << std::dec << "\nCheckers: ";
for (Bitboard b = pos.checkers(); b; )
- os << UCI::square(pop_lsb(&b)) << " ";
+ os << UCI::square(pop_lsb(b)) << " ";
if ( int(Tablebases::MaxCardinality) >= popcount(pos.pieces())
&& !pos.can_castle(ANY_CASTLING))
{
StateInfo st;
+ ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
+
Position p;
p.set(pos.fen(), pos.is_chess960(), &st, pos.this_thread());
Tablebases::ProbeState s1, s2;
}
-// Marcel van Kervinck's cuckoo algorithm for fast detection of "upcoming repetition"
-// situations. Description of the algorithm in the following paper:
-// https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf
+// Implements Marcel van Kervinck's cuckoo algorithm to detect repetition of positions
+// for 3-fold repetition draws. The algorithm uses two hash tables with Zobrist hashes
+// to allow fast detection of recurring positions. For details see:
+// http://web.archive.org/web/20201107002606/https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf
// First and second hash functions for indexing the cuckoo tables
inline int H1(Key h) { return h & 0x1fff; }
Zobrist::castling[cr] = rng.rand<Key>();
Zobrist::side = rng.rand<Key>();
- Zobrist::noPawns = rng.rand<Key>();
// Prepare the cuckoo tables
std::memset(cuckoo, 0, sizeof(cuckoo));
std::memset(cuckooMove, 0, sizeof(cuckooMove));
- int count = 0;
+ [[maybe_unused]] int count = 0;
for (Piece pc : Pieces)
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2)
4) En passant target square (in algebraic notation). If there's no en passant
target square, this is "-". If a pawn has just made a 2-square move, this
- is the position "behind" the pawn. Following X-FEN standard, this is recorded only
- if there is a pawn in position to make an en passant capture, and if there really
- is a pawn that might have advanced two squares.
+ is the position "behind" the pawn. Following X-FEN standard, this is recorded
+ only if there is a pawn in position to make an en passant capture, and if
+ there really is a pawn that might have advanced two squares.
5) Halfmove clock. This is the number of halfmoves since the last pawn advance
or capture. This is used to determine if a draw can be claimed under the
std::memset(this, 0, sizeof(Position));
std::memset(si, 0, sizeof(StateInfo));
- std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE);
st = si;
ss >> std::noskipws;
chess960 = isChess960;
thisThread = th;
- set_state(st);
- st->accumulator.state[WHITE] = Eval::NNUE::INIT;
- st->accumulator.state[BLACK] = Eval::NNUE::INIT;
+ set_state();
assert(pos_is_ok());
Square kto = relative_square(c, cr & KING_SIDE ? SQ_G1 : SQ_C1);
Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1);
- castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto)
+ castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto))
& ~(kfrom | rfrom);
}
/// Position::set_check_info() sets king attacks to detect if a move gives check
-void Position::set_check_info(StateInfo* si) const {
+void Position::set_check_info() const {
- si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square<KING>(WHITE), si->pinners[BLACK]);
- si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square<KING>(BLACK), si->pinners[WHITE]);
+ update_slider_blockers(WHITE);
+ update_slider_blockers(BLACK);
Square ksq = square<KING>(~sideToMove);
- si->checkSquares[PAWN] = pawn_attacks_bb(~sideToMove, ksq);
- si->checkSquares[KNIGHT] = attacks_bb<KNIGHT>(ksq);
- si->checkSquares[BISHOP] = attacks_bb<BISHOP>(ksq, pieces());
- si->checkSquares[ROOK] = attacks_bb<ROOK>(ksq, pieces());
- si->checkSquares[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK];
- si->checkSquares[KING] = 0;
+ st->checkSquares[PAWN] = pawn_attacks_bb(~sideToMove, ksq);
+ st->checkSquares[KNIGHT] = attacks_bb<KNIGHT>(ksq);
+ st->checkSquares[BISHOP] = attacks_bb<BISHOP>(ksq, pieces());
+ st->checkSquares[ROOK] = attacks_bb<ROOK>(ksq, pieces());
+ st->checkSquares[QUEEN] = st->checkSquares[BISHOP] | st->checkSquares[ROOK];
+ st->checkSquares[KING] = 0;
}
/// 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.
+/// The function is only used when a new position is set up
-void Position::set_state(StateInfo* si) const {
+void Position::set_state() const {
- si->key = si->materialKey = 0;
- si->pawnKey = Zobrist::noPawns;
- si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO;
- si->checkersBB = attackers_to(square<KING>(sideToMove)) & pieces(~sideToMove);
+ st->key = st->materialKey = 0;
+ st->nonPawnMaterial[WHITE] = st->nonPawnMaterial[BLACK] = VALUE_ZERO;
+ st->checkersBB = attackers_to(square<KING>(sideToMove)) & pieces(~sideToMove);
- set_check_info(si);
+ set_check_info();
for (Bitboard b = pieces(); b; )
{
- Square s = pop_lsb(&b);
+ Square s = pop_lsb(b);
Piece pc = piece_on(s);
- si->key ^= Zobrist::psq[pc][s];
-
- if (type_of(pc) == PAWN)
- si->pawnKey ^= Zobrist::psq[pc][s];
+ st->key ^= Zobrist::psq[pc][s];
- else if (type_of(pc) != KING)
- si->nonPawnMaterial[color_of(pc)] += PieceValue[MG][pc];
+ if (type_of(pc) != KING && type_of(pc) != PAWN)
+ st->nonPawnMaterial[color_of(pc)] += PieceValue[pc];
}
- if (si->epSquare != SQ_NONE)
- si->key ^= Zobrist::enpassant[file_of(si->epSquare)];
+ if (st->epSquare != SQ_NONE)
+ st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
if (sideToMove == BLACK)
- si->key ^= Zobrist::side;
+ st->key ^= Zobrist::side;
- si->key ^= Zobrist::castling[si->castlingRights];
+ st->key ^= Zobrist::castling[st->castlingRights];
for (Piece pc : Pieces)
for (int cnt = 0; cnt < pieceCount[pc]; ++cnt)
- si->materialKey ^= Zobrist::psq[pc][cnt];
+ st->materialKey ^= Zobrist::psq[pc][cnt];
}
/// 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 {
+string Position::fen() const {
int emptyCnt;
std::ostringstream ss;
return ss.str();
}
+/// update_slider_blockers() calculates st->blockersForKing[c] and st->pinners[~c],
+/// which store respectively the pieces preventing king of color c from being in check
+/// and the slider pieces of color ~c pinning pieces of color c to the king.
+void Position::update_slider_blockers(Color c) const {
-/// Position::slider_blockers() returns a bitboard of all the pieces (both colors)
-/// that are blocking attacks on the square 's' from 'sliders'. A piece blocks a
-/// slider if removing that piece from the board would result in a position where
-/// square 's' is attacked. For example, a king-attack blocking piece can be either
-/// a pinned or a discovered check piece, according if its color is the opposite
-/// or the same of the color of the slider.
+ Square ksq = square<KING>(c);
-Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const {
-
- Bitboard blockers = 0;
- pinners = 0;
+ st->blockersForKing[c] = 0;
+ st->pinners[~c] = 0;
// Snipers are sliders that attack 's' when a piece and other snipers are removed
- Bitboard snipers = ( (attacks_bb< ROOK>(s) & pieces(QUEEN, ROOK))
- | (attacks_bb<BISHOP>(s) & pieces(QUEEN, BISHOP))) & sliders;
+ Bitboard snipers = ( (attacks_bb< ROOK>(ksq) & pieces(QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(ksq) & pieces(QUEEN, BISHOP))) & pieces(~c);
Bitboard occupancy = pieces() ^ snipers;
while (snipers)
{
- Square sniperSq = pop_lsb(&snipers);
- Bitboard b = between_bb(s, sniperSq) & occupancy;
+ Square sniperSq = pop_lsb(snipers);
+ Bitboard b = between_bb(ksq, sniperSq) & occupancy;
if (b && !more_than_one(b))
{
- blockers |= b;
- if (b & pieces(color_of(piece_on(s))))
- pinners |= sniperSq;
+ st->blockersForKing[c] |= b;
+ if (b & pieces(c))
+ st->pinners[~c] |= sniperSq;
}
}
- return blockers;
}
// 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 (type_of(m) == ENPASSANT)
+ if (type_of(m) == EN_PASSANT)
{
Square ksq = square<KING>(us);
Square capsq = to - pawn_push(us);
if (attackers_to(s) & pieces(~us))
return false;
- // In case of Chess960, verify that when moving the castling rook we do
- // not discover some hidden checker.
+ // In case of Chess960, verify if the Rook blocks some checks
// For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
- return !chess960
- || !(attacks_bb<ROOK>(to, pieces() ^ to_sq(m)) & pieces(~us, ROOK, QUEEN));
+ return !chess960 || !(blockers_for_king(us) & to_sq(m));
}
// If the moving piece is a king, check whether the destination square is
// attacked by the opponent.
if (type_of(piece_on(from)) == KING)
- return !(attackers_to(to) & pieces(~us));
+ return !(attackers_to(to, pieces() ^ from) & 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 !(blockers_for_king(us) & from)
- || aligned(from, to, square<KING>(us));
+ return !(blockers_for_king(us) & from)
+ || aligned(from, to, square<KING>(us));
}
/// 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
+/// 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::pseudo_legal(const Move m) const {
Piece pc = moved_piece(m);
// Use a slower but simpler function for uncommon cases
+ // yet we skip the legality check of MoveList<LEGAL>().
if (type_of(m) != NORMAL)
- return MoveList<LEGAL>(*this).contains(m);
+ return checkers() ? MoveList< EVASIONS>(*this).contains(m)
+ : MoveList<NON_EVASIONS>(*this).contains(m);
- // Is not a promotion, so promotion piece must be empty
- if (promotion_type(m) - KNIGHT != NO_PIECE_TYPE)
- return false;
+ // Is not a promotion, so the promotion piece must be empty
+ assert(promotion_type(m) - KNIGHT == NO_PIECE_TYPE);
// If the 'from' square is not occupied by a piece belonging to the side to
// move, the move is obviously not legal.
return false;
if ( !(pawn_attacks_bb(us, from) & pieces(~us) & to) // Not a capture
- && !((from + pawn_push(us) == to) && empty(to)) // Not a single push
- && !( (from + 2 * pawn_push(us) == to) // Not a double push
+ && !((from + pawn_push(us) == to) && empty(to)) // Not a single push
+ && !( (from + 2 * pawn_push(us) == to) // Not a double push
&& (relative_rank(us, from) == RANK_2)
&& empty(to)
&& empty(to - pawn_push(us))))
{
if (type_of(pc) != KING)
{
- // Double check? In this case a king move is required
+ // Double check? In this case, a king move is required
if (more_than_one(checkers()))
return false;
- // Our move must be a blocking evasion or a capture of the checking piece
- if (!((between_bb(lsb(checkers()), square<KING>(us)) | checkers()) & to))
+ // Our move must be a blocking interposition or a capture of the checking piece
+ if (!(between_bb(square<KING>(us), lsb(checkers())) & to))
return false;
}
- // In case of king moves under check we have to remove king so as to catch
+ // In case of king moves under check we have to remove the 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;
return true;
// Is there a discovered check?
- if ( (blockers_for_king(~sideToMove) & from)
- && !aligned(from, to, square<KING>(~sideToMove)))
- return true;
+ if (blockers_for_king(~sideToMove) & from)
+ return !aligned(from, to, square<KING>(~sideToMove))
+ || type_of(m) == CASTLING;
switch (type_of(m))
{
// 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:
+ case EN_PASSANT:
{
Square capsq = make_square(file_of(to), rank_of(from));
Bitboard b = (pieces() ^ from ^ capsq) | to;
return (attacks_bb< ROOK>(square<KING>(~sideToMove), b) & pieces(sideToMove, QUEEN, ROOK))
| (attacks_bb<BISHOP>(square<KING>(~sideToMove), b) & pieces(sideToMove, QUEEN, BISHOP));
}
- case CASTLING:
+ default: //CASTLING
{
- Square kfrom = from;
- 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);
+ // Castling is encoded as 'king captures the rook'
+ Square rto = relative_square(sideToMove, to > from ? SQ_F1 : SQ_D1);
- return (attacks_bb<ROOK>(rto) & square<KING>(~sideToMove))
- && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square<KING>(~sideToMove));
+ return check_squares(ROOK) & rto;
}
- default:
- assert(false);
- return false;
}
}
++st->pliesFromNull;
// Used by NNUE
- st->accumulator.state[WHITE] = Eval::NNUE::EMPTY;
- st->accumulator.state[BLACK] = Eval::NNUE::EMPTY;
+ st->accumulator.computed[WHITE] = false;
+ st->accumulator.computed[BLACK] = false;
auto& dp = st->dirtyPiece;
dp.dirty_num = 1;
Square from = from_sq(m);
Square to = to_sq(m);
Piece pc = piece_on(from);
- Piece captured = type_of(m) == ENPASSANT ? make_piece(them, PAWN) : piece_on(to);
+ Piece captured = type_of(m) == EN_PASSANT ? make_piece(them, PAWN) : piece_on(to);
assert(color_of(pc) == us);
assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us));
// update non-pawn material.
if (type_of(captured) == PAWN)
{
- if (type_of(m) == ENPASSANT)
+ if (type_of(m) == EN_PASSANT)
{
capsq -= pawn_push(us);
assert(piece_on(to) == NO_PIECE);
assert(piece_on(capsq) == make_piece(them, PAWN));
}
-
- st->pawnKey ^= Zobrist::psq[captured][capsq];
}
else
- st->nonPawnMaterial[them] -= PieceValue[MG][captured];
+ st->nonPawnMaterial[them] -= PieceValue[captured];
- if (Eval::useNNUE)
- {
- dp.dirty_num = 2; // 1 piece moved, 1 piece captured
- dp.piece[1] = captured;
- dp.from[1] = capsq;
- dp.to[1] = SQ_NONE;
- }
+ dp.dirty_num = 2; // 1 piece moved, 1 piece captured
+ dp.piece[1] = captured;
+ dp.from[1] = capsq;
+ dp.to[1] = SQ_NONE;
// Update board and piece lists
remove_piece(capsq);
- if (type_of(m) == ENPASSANT)
- board[capsq] = NO_PIECE;
-
// Update material hash key and prefetch access to materialTable
k ^= Zobrist::psq[captured][capsq];
st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]];
- prefetch(thisThread->materialTable[st->materialKey]);
// Reset rule 50 counter
st->rule50 = 0;
// Move the piece. The tricky Chess960 castling is handled earlier
if (type_of(m) != CASTLING)
{
- if (Eval::useNNUE)
- {
- dp.piece[0] = pc;
- dp.from[0] = from;
- dp.to[0] = to;
- }
+ dp.piece[0] = pc;
+ dp.from[0] = from;
+ dp.to[0] = to;
move_piece(from, to);
}
// If the moving piece is a pawn do some special extra work
if (type_of(pc) == PAWN)
{
- // Set en-passant square if the moved pawn can be captured
+ // Set en passant square if the moved pawn can be captured
if ( (int(to) ^ int(from)) == 16
&& (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN)))
{
remove_piece(to);
put_piece(promotion, to);
- if (Eval::useNNUE)
- {
- // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE
- dp.to[0] = SQ_NONE;
- dp.piece[dp.dirty_num] = promotion;
- dp.from[dp.dirty_num] = SQ_NONE;
- dp.to[dp.dirty_num] = to;
- dp.dirty_num++;
- }
+ // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE
+ dp.to[0] = SQ_NONE;
+ dp.piece[dp.dirty_num] = promotion;
+ dp.from[dp.dirty_num] = SQ_NONE;
+ dp.to[dp.dirty_num] = to;
+ dp.dirty_num++;
// Update hash keys
k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to];
- st->pawnKey ^= Zobrist::psq[pc][to];
st->materialKey ^= Zobrist::psq[promotion][pieceCount[promotion]-1]
^ Zobrist::psq[pc][pieceCount[pc]];
// Update material
- st->nonPawnMaterial[us] += PieceValue[MG][promotion];
+ st->nonPawnMaterial[us] += PieceValue[promotion];
}
- // Update pawn hash key
- st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
-
// Reset rule 50 draw counter
st->rule50 = 0;
}
sideToMove = ~sideToMove;
// Update king attacks used for fast check detection
- set_check_info(st);
+ set_check_info();
// Calculate the repetition info. It is the ply distance from the previous
// occurrence of the same position, negative in the 3-fold case, or zero
{
Square capsq = to;
- if (type_of(m) == ENPASSANT)
+ if (type_of(m) == EN_PASSANT)
{
capsq -= pawn_push(us);
rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
- if (Do && Eval::useNNUE)
+ if (Do)
{
auto& dp = st->dirtyPiece;
dp.piece[0] = make_piece(us, KING);
// Remove both pieces first since squares could overlap in Chess960
remove_piece(Do ? from : to);
remove_piece(Do ? rfrom : rto);
- board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do this for us
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // remove_piece does not do this for us
put_piece(make_piece(us, KING), Do ? to : from);
put_piece(make_piece(us, ROOK), Do ? rto : rfrom);
}
-/// Position::do(undo)_null_move() is used to do(undo) a "null move": it flips
+/// Position::do_null_move() is used to do a "null move": it flips
/// the side to move without executing any move on the board.
void Position::do_null_move(StateInfo& newSt) {
st->dirtyPiece.dirty_num = 0;
st->dirtyPiece.piece[0] = NO_PIECE; // Avoid checks in UpdateAccumulator()
- st->accumulator.state[WHITE] = Eval::NNUE::EMPTY;
- st->accumulator.state[BLACK] = Eval::NNUE::EMPTY;
+ st->accumulator.computed[WHITE] = false;
+ st->accumulator.computed[BLACK] = false;
if (st->epSquare != SQ_NONE)
{
}
st->key ^= Zobrist::side;
- prefetch(TT.first_entry(st->key));
-
++st->rule50;
+ prefetch(TT.first_entry(key()));
+
st->pliesFromNull = 0;
sideToMove = ~sideToMove;
- set_check_info(st);
+ set_check_info();
st->repetition = 0;
assert(pos_is_ok());
}
+
+/// Position::undo_null_move() must be used to undo a "null move"
+
void Position::undo_null_move() {
assert(!checkers());
/// 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.
+/// en passant and promotions.
Key Position::key_after(Move m) const {
if (captured)
k ^= Zobrist::psq[captured][to];
- return k ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
+ k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
+
+ return (captured || type_of(pc) == PAWN)
+ ? k : adjust_key50<true>(k);
}
assert(is_ok(m));
- // Only deal with normal moves, assume others pass a simple see
+ // Only deal with normal moves, assume others pass a simple SEE
if (type_of(m) != NORMAL)
return VALUE_ZERO >= threshold;
Square from = from_sq(m), to = to_sq(m);
- int swap = PieceValue[MG][piece_on(to)] - threshold;
+ int swap = PieceValue[piece_on(to)] - threshold;
if (swap < 0)
return false;
- swap = PieceValue[MG][piece_on(from)] - swap;
+ swap = PieceValue[piece_on(from)] - swap;
if (swap <= 0)
return true;
- Bitboard occupied = pieces() ^ from ^ to;
- Color stm = color_of(piece_on(from));
+ assert(color_of(piece_on(from)) == sideToMove);
+ Bitboard occupied = pieces() ^ from ^ to; // xoring to is important for pinned piece logic
+ Color stm = sideToMove;
Bitboard attackers = attackers_to(to, occupied);
Bitboard stmAttackers, bb;
int res = 1;
if (!(stmAttackers = attackers & pieces(stm)))
break;
- // Don't allow pinned pieces to attack (except the king) as long as
- // there are pinners on their original square.
+ // Don't allow pinned pieces to attack as long as there are
+ // pinners on their original square.
if (pinners(~stm) & occupied)
+ {
stmAttackers &= ~blockers_for_king(stm);
- if (!stmAttackers)
- break;
+ if (!stmAttackers)
+ break;
+ }
res ^= 1;
// the bitboard 'attackers' any X-ray attackers behind it.
if ((bb = stmAttackers & pieces(PAWN)))
{
- if ((swap = PawnValueMg - swap) < res)
+ if ((swap = PawnValue - swap) < res)
break;
+ occupied ^= least_significant_square_bb(bb);
- occupied ^= lsb(bb);
attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
}
else if ((bb = stmAttackers & pieces(KNIGHT)))
{
- if ((swap = KnightValueMg - swap) < res)
+ if ((swap = KnightValue - swap) < res)
break;
-
- occupied ^= lsb(bb);
+ occupied ^= least_significant_square_bb(bb);
}
else if ((bb = stmAttackers & pieces(BISHOP)))
{
- if ((swap = BishopValueMg - swap) < res)
+ if ((swap = BishopValue - swap) < res)
break;
+ occupied ^= least_significant_square_bb(bb);
- occupied ^= lsb(bb);
attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
}
else if ((bb = stmAttackers & pieces(ROOK)))
{
- if ((swap = RookValueMg - swap) < res)
+ if ((swap = RookValue - swap) < res)
break;
+ occupied ^= least_significant_square_bb(bb);
- occupied ^= lsb(bb);
attackers |= attacks_bb<ROOK>(to, occupied) & pieces(ROOK, QUEEN);
}
else if ((bb = stmAttackers & pieces(QUEEN)))
{
- if ((swap = QueenValueMg - swap) < res)
+ if ((swap = QueenValue - swap) < res)
break;
+ occupied ^= least_significant_square_bb(bb);
- occupied ^= lsb(bb);
attackers |= (attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN))
| (attacks_bb<ROOK >(to, occupied) & pieces(ROOK , QUEEN));
}
else // KING
- // If we "capture" with the king but opponent still has attackers,
+ // If we "capture" with the king but the opponent still has attackers,
// reverse the result.
return (attackers & ~pieces(stm)) ? res ^ 1 : res;
}
return bool(res);
}
-
/// Position::is_draw() tests whether the position is drawn by 50-move rule
/// or by repetition. It does not detect stalemates.
Square s1 = from_sq(move);
Square s2 = to_sq(move);
- if (!(between_bb(s1, s2) & pieces()))
+ if (!((between_bb(s1, s2) ^ s2) & pieces()))
{
if (ply > i)
return true;
/// Position::pos_is_ok() performs some consistency checks for the
-/// position object and raises an asserts if something wrong is detected.
+/// position object and raise an assert if something wrong is detected.
/// This is meant to be helpful when debugging.
bool Position::pos_is_ok() const {
if (p1 != p2 && (pieces(p1) & pieces(p2)))
assert(0 && "pos_is_ok: Bitboards");
- StateInfo si = *st;
- set_state(&si);
- if (std::memcmp(&si, st, sizeof(StateInfo)))
- assert(0 && "pos_is_ok: State");
for (Piece pc : Pieces)
- {
if ( pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc)))
|| pieceCount[pc] != std::count(board, board + SQUARE_NB, pc))
assert(0 && "pos_is_ok: Pieces");
- for (int i = 0; i < pieceCount[pc]; ++i)
- if (board[pieceList[pc][i]] != pc || index[pieceList[pc][i]] != i)
- assert(0 && "pos_is_ok: Index");
- }
-
for (Color c : { WHITE, BLACK })
for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE})
{
return true;
}
+
+} // namespace Stockfish
projects / stockfish / blobdiff