/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2012 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
#include <fstream>
#include <iostream>
#include <sstream>
+#include <algorithm>
#include "bitcount.h"
#include "movegen.h"
const Score TempoValue = make_score(48, 22);
// To convert a Piece to and from a FEN char
- const string PieceToChar(".PNBRQK pnbrqk ");
+ const string PieceToChar(" PNBRQK pnbrqk .");
}
CheckInfo::CheckInfo(const Position& pos) {
- Color them = flip(pos.side_to_move());
- Square ksq = pos.king_square(them);
+ Color them = ~pos.side_to_move();
+ ksq = pos.king_square(them);
pinned = pos.pinned_pieces();
dcCandidates = pos.discovered_check_candidates();
checkSq[BISHOP] = pos.attacks_from<BISHOP>(ksq);
checkSq[ROOK] = pos.attacks_from<ROOK>(ksq);
checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK];
- checkSq[KING] = EmptyBoardBB;
+ checkSq[KING] = 0;
}
/// or the FEN string, we want the new born Position object do not depend
/// on any external data so we detach state pointer from the source one.
-Position::Position(const Position& pos, int th) {
+void Position::copy(const Position& pos, int th) {
memcpy(this, &pos, sizeof(Position));
+ startState = *st;
+ st = &startState;
threadID = th;
nodes = 0;
/*
A FEN string defines a particular position using only the ASCII character set.
- A FEN string contains six fields. The separator between fields is a space. The fields are:
+ 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 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 noted using digits 1 through 8 (the number
- of blank squares), and "/" separate ranks.
+ 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
+ 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
+ noted using digits 1 through 8 (the number of blank squares), and "/"
+ separates ranks.
2) Active color. "w" means white moves next, "b" means black.
- 3) Castling availability. If neither side can castle, this is "-". Otherwise, this has one or more
- letters: "K" (White can castle kingside), "Q" (White can castle queenside), "k" (Black can castle
- kingside), and/or "q" (Black can castle queenside).
+ 3) Castling availability. If neither side can castle, this is "-". Otherwise,
+ this has one or more letters: "K" (White can castle kingside), "Q" (White
+ can castle queenside), "k" (Black can castle kingside), and/or "q" (Black
+ can castle queenside).
- 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. This is recorded
- regardless of whether there is a pawn in position to make an en passant capture.
+ 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. This is recorded regardless of whether
+ there is a pawn in position to make an en passant capture.
- 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 fifty-move rule.
+ 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
+ fifty-move rule.
- 6) Fullmove number: The number of the full move. It starts at 1, and is incremented after Black's move.
+ 6) Fullmove number. The number of the full move. It starts at 1, and is
+ incremented after Black's move.
*/
char col, row, token;
// 1. Piece placement
while ((fen >> token) && !isspace(token))
{
- if (token == '/')
- sq -= Square(16); // Jump back of 2 rows
+ if (isdigit(token))
+ sq += Square(token - '0'); // Advance the given number of files
- else if (isdigit(token))
- sq += Square(token - '0'); // Skip the given number of files
+ else if (token == '/')
+ sq = make_square(FILE_A, rank_of(sq) - Rank(2));
else if ((p = PieceToChar.find(token)) != string::npos)
{
{
Square rsq;
Color c = islower(token) ? BLACK : WHITE;
- Piece rook = make_piece(c, ROOK);
token = char(toupper(token));
if (token == 'K')
- for (rsq = relative_square(c, SQ_H1); 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); 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 = make_square(File(token - 'A'), relative_rank(c, RANK_1));
else
continue;
- set_castle_right(king_square(c), rsq);
+ set_castle_right(c, rsq);
}
// 4. En passant square. Ignore if no pawn capture is possible
// Convert from fullmove starting from 1 to ply starting from 0,
// handle also common incorrect FEN with fullmove = 0.
- startPosPly = Max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
+ startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
st->key = compute_key();
st->pawnKey = compute_pawn_key();
st->value = compute_value();
st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
+ st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
chess960 = isChess960;
assert(pos_is_ok());
/// Position::set_castle_right() is an helper function used to set castling
-/// rights given the corresponding king and rook starting squares.
+/// rights given the corresponding color and the rook starting square.
-void Position::set_castle_right(Square ksq, Square rsq) {
+void Position::set_castle_right(Color c, Square rsq) {
- int f = (rsq < ksq ? WHITE_OOO : WHITE_OO) << color_of(piece_on(ksq));
+ int f = (rsq < king_square(c) ? WHITE_OOO : WHITE_OO) << c;
st->castleRights |= f;
- castleRightsMask[ksq] ^= f;
+ castleRightsMask[king_square(c)] ^= f;
castleRightsMask[rsq] ^= f;
castleRookSquare[f] = rsq;
}
{
sq = make_square(file, rank);
- if (!square_is_empty(sq))
+ if (square_is_empty(sq))
+ emptyCnt++;
+ else
{
- if (emptyCnt)
+ if (emptyCnt > 0)
{
fen << emptyCnt;
emptyCnt = 0;
}
fen << PieceToChar[piece_on(sq)];
}
- else
- emptyCnt++;
}
- if (emptyCnt)
+ if (emptyCnt > 0)
fen << emptyCnt;
if (rank > RANK_1)
fen << (sideToMove == WHITE ? " w " : " b ");
- if (st->castleRights != CASTLES_NONE)
- {
- if (can_castle(WHITE_OO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K');
+ if (can_castle(WHITE_OO))
+ fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K');
- if (can_castle(WHITE_OOO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q');
+ if (can_castle(WHITE_OOO))
+ fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q');
- if (can_castle(BLACK_OO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k');
+ if (can_castle(BLACK_OO))
+ fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k');
- if (can_castle(BLACK_OOO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q');
- } else
+ if (can_castle(BLACK_OOO))
+ fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q');
+
+ if (st->castleRights == CASTLES_NONE)
fen << '-';
- fen << (ep_square() == SQ_NONE ? " -" : " " + square_to_string(ep_square()))
- << " " << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+ fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
return fen.str();
}
if (move)
{
Position p(*this, thread());
- string dd = (sideToMove == BLACK ? ".." : "");
- cout << "\nMove is: " << dd << move_to_san(p, move);
+ cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move);
}
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
{
Square sq = make_square(file, rank);
Piece piece = piece_on(sq);
+ char c = (color_of(piece) == BLACK ? '=' : ' ');
- if (piece == PIECE_NONE && color_of(sq) == DARK)
- piece = PIECE_NONE_DARK_SQ;
+ if (piece == NO_PIECE && !opposite_colors(sq, SQ_A1))
+ piece++; // Index the dot
- char c = (color_of(piece_on(sq)) == BLACK ? '=' : ' ');
cout << c << PieceToChar[piece] << c << '|';
}
}
/// king) pieces for the given color. Or, when template parameter FindPinned is
/// false, the function return the pieces of the given color candidate for a
/// discovery check against the enemy king.
-
template<bool FindPinned>
Bitboard Position::hidden_checkers() const {
// Pinned pieces protect our king, dicovery checks attack the enemy king
- Bitboard b, result = EmptyBoardBB;
- Bitboard pinners = pieces(FindPinned ? flip(sideToMove) : sideToMove);
- Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove));
+ Bitboard b, result = 0;
+ Bitboard pinners = pieces(FindPinned ? ~sideToMove : sideToMove);
+ Square ksq = king_square(FindPinned ? sideToMove : ~sideToMove);
// Pinners are sliders, that give check when candidate pinned is removed
- pinners &= (pieces(ROOK, QUEEN) & RookPseudoAttacks[ksq])
- | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]);
+ pinners &= (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq])
+ | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]);
while (pinners)
{
return result;
}
+// Explicit template instantiations
+template Bitboard Position::hidden_checkers<true>() const;
+template Bitboard Position::hidden_checkers<false>() const;
-/// Position:pinned_pieces() returns a bitboard of all pinned (against the
-/// king) pieces for the side to move.
-
-Bitboard Position::pinned_pieces() const {
-
- return hidden_checkers<true>();
-}
-
-
-/// Position:discovered_check_candidates() returns a bitboard containing all
-/// pieces for the side to move which are candidates for giving a discovered
-/// check.
-
-Bitboard Position::discovered_check_candidates() const {
-
- return hidden_checkers<false>();
-}
-/// Position::attackers_to() computes a bitboard of all pieces which attacks a
+/// 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 {
| (attacks_from<KING>(s) & pieces(KING));
}
+
/// 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.
assert(square_is_ok(s));
- switch (p)
+ switch (type_of(p))
{
- case WB: case BB: return bishop_attacks_bb(s, occ);
- case WR: case BR: return rook_attacks_bb(s, occ);
- case WQ: case BQ: return bishop_attacks_bb(s, occ) | rook_attacks_bb(s, occ);
- default: return StepAttacksBB[p][s];
+ case BISHOP: return bishop_attacks_bb(s, occ);
+ case ROOK : return rook_attacks_bb(s, occ);
+ case QUEEN : return bishop_attacks_bb(s, occ) | rook_attacks_bb(s, occ);
+ default : return StepAttacksBB[p][s];
}
}
assert(square_is_ok(s));
Bitboard occ, xray;
- Square f = move_from(m), t = move_to(m);
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece piece = piece_on(from);
+
+ assert(!square_is_empty(from));
- assert(!square_is_empty(f));
+ // Update occupancy as if the piece is moving
+ occ = occupied_squares();
+ do_move_bb(&occ, make_move_bb(from, to));
- if (bit_is_set(attacks_from(piece_on(f), t), s))
+ // The piece moved in 'to' attacks the square 's' ?
+ if (bit_is_set(attacks_from(piece, to, occ), s))
return true;
- // Move the piece and scan for X-ray attacks behind it
- occ = occupied_squares();
- do_move_bb(&occ, make_move_bb(f, t));
- xray = ( (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN))
- |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN)))
- & pieces(color_of(piece_on(f)));
+ // Scan for possible X-ray attackers behind the moved piece
+ xray = (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN, color_of(piece)))
+ |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN, color_of(piece)));
- // If we have attacks we need to verify that are caused by our move
- // and are not already existent ones.
+ // Verify attackers are triggered by our move and not already existing
return xray && (xray ^ (xray & attacks_from<QUEEN>(s)));
}
assert(is_ok(m));
assert(pinned == pinned_pieces());
- Color us = side_to_move();
- Square from = move_from(m);
+ Color us = sideToMove;
+ Square from = from_sq(m);
assert(color_of(piece_on(from)) == us);
assert(piece_on(king_square(us)) == make_piece(us, KING));
// the move is made.
if (is_enpassant(m))
{
- Color them = flip(us);
- Square to = move_to(m);
+ Color them = ~us;
+ Square to = to_sq(m);
Square capsq = to + pawn_push(them);
Square ksq = king_square(us);
Bitboard b = occupied_squares();
assert(to == ep_square());
assert(piece_on(from) == make_piece(us, PAWN));
assert(piece_on(capsq) == make_piece(them, PAWN));
- assert(piece_on(to) == PIECE_NONE);
+ assert(piece_on(to) == NO_PIECE);
clear_bit(&b, from);
clear_bit(&b, capsq);
// square is attacked by the opponent. Castling moves are checked
// for legality during move generation.
if (type_of(piece_on(from)) == KING)
- return is_castle(m) || !(attackers_to(move_to(m)) & pieces(flip(us)));
+ return is_castle(m) || !(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
|| !bit_is_set(pinned, from)
- || squares_aligned(from, move_to(m), king_square(us));
+ || squares_aligned(from, to_sq(m), king_square(us));
}
/// Position::move_is_legal() takes a random move and tests whether the move
-/// is legal. This version is not very fast and should be used only
-/// in non time-critical paths.
+/// is legal. This version is not very fast and should be used only in non
+/// time-critical paths.
bool Position::move_is_legal(const Move m) const {
bool Position::is_pseudo_legal(const Move m) const {
Color us = sideToMove;
- Color them = flip(sideToMove);
- Square from = move_from(m);
- Square to = move_to(m);
+ Color them = ~sideToMove;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
Piece pc = piece_on(from);
// Use a slower but simpler function for uncommon cases
return move_is_legal(m);
// Is not a promotion, so promotion piece must be empty
- if (promotion_piece_type(m) - 2 != PIECE_TYPE_NONE)
+ if (promotion_piece_type(m) - 2 != NO_PIECE_TYPE)
return false;
// If the from square is not occupied by a piece belonging to the side to
// move, the move is obviously not legal.
- if (pc == PIECE_NONE || color_of(pc) != us)
+ if (pc == NO_PIECE || color_of(pc) != us)
return false;
// The destination square cannot be occupied by a friendly piece
{
Bitboard b = occupied_squares();
clear_bit(&b, from);
- if (attackers_to(move_to(m), b) & pieces(flip(us)))
+ if (attackers_to(to_sq(m), b) & pieces(~us))
return false;
}
else
// Our move must be a blocking evasion or a capture of the checking piece
target = squares_between(checksq, king_square(us)) | checkers();
- if (!bit_is_set(target, move_to(m)))
+ if (!bit_is_set(target, to_sq(m)))
return false;
}
}
assert(is_ok(m));
assert(ci.dcCandidates == discovered_check_candidates());
- assert(color_of(piece_on(move_from(m))) == side_to_move());
+ assert(color_of(piece_moved(m)) == sideToMove);
- Square from = move_from(m);
- Square to = move_to(m);
+ Square from = from_sq(m);
+ Square to = to_sq(m);
PieceType pt = type_of(piece_on(from));
// Direct check ?
{
// For pawn and king moves we need to verify also direction
if ( (pt != PAWN && pt != KING)
- || !squares_aligned(from, to, king_square(flip(side_to_move()))))
+ || !squares_aligned(from, to, king_square(~sideToMove)))
return true;
}
if (!is_special(m))
return false;
- Color us = side_to_move();
+ Color us = sideToMove;
Bitboard b = occupied_squares();
- Square ksq = king_square(flip(us));
+ Square ksq = king_square(~us);
// Promotion with check ?
if (is_promotion(m))
assert(&newSt != st);
nodes++;
- Key key = st->key;
+ Key k = st->key;
- // 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.
+ // 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 pawnKey, materialKey;
Value npMaterial[2];
st = &newSt;
// Update side to move
- key ^= zobSideToMove;
+ k ^= zobSideToMove;
// Increment the 50 moves rule draw counter. Resetting it to zero in the
// case of non-reversible moves is taken care of later.
if (is_castle(m))
{
- st->key = key;
+ st->key = k;
do_castle_move<true>(m);
return;
}
- Color us = side_to_move();
- Color them = flip(us);
- Square from = move_from(m);
- Square to = move_to(m);
- bool ep = is_enpassant(m);
- bool pm = is_promotion(m);
-
+ Color us = sideToMove;
+ Color them = ~us;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
Piece piece = piece_on(from);
PieceType pt = type_of(piece);
- PieceType capture = ep ? PAWN : type_of(piece_on(to));
+ PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to));
- assert(color_of(piece_on(from)) == us);
- assert(color_of(piece_on(to)) == them || square_is_empty(to));
+ assert(color_of(piece) == us);
+ assert(color_of(piece_on(to)) != us);
assert(capture != KING);
if (capture)
{
Square capsq = to;
- // If the captured piece was a pawn, update pawn hash key, otherwise
+ // If the captured piece is a pawn, update pawn hash key, otherwise
// update non-pawn material.
if (capture == PAWN)
{
- if (ep) // En passant?
+ if (is_enpassant(m))
{
capsq += pawn_push(them);
assert(pt == PAWN);
assert(to == st->epSquare);
assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(to) == PIECE_NONE);
+ assert(piece_on(to) == NO_PIECE);
assert(piece_on(capsq) == make_piece(them, PAWN));
- board[capsq] = PIECE_NONE;
+ board[capsq] = NO_PIECE;
}
st->pawnKey ^= zobrist[them][PAWN][capsq];
else
st->npMaterial[them] -= PieceValueMidgame[capture];
- // Remove captured piece
+ // Remove the captured piece
clear_bit(&byColorBB[them], capsq);
clear_bit(&byTypeBB[capture], capsq);
clear_bit(&occupied, capsq);
- // Update hash key
- key ^= zobrist[them][capture][capsq];
-
- // Update incremental scores
- st->value -= pst(make_piece(them, capture), capsq);
-
- // Update piece count
- pieceCount[them][capture]--;
+ // Update piece list, move the last piece at index[capsq] position and
+ // shrink the list.
+ //
+ // WARNING: This is a not revresible operation. When we will reinsert the
+ // captured piece in undo_move() we will put it at the end of the list and
+ // not in its original place, it means index[] and pieceList[] are not
+ // guaranteed to be invariant to a do_move() + undo_move() sequence.
+ Square lastSquare = pieceList[them][capture][--pieceCount[them][capture]];
+ index[lastSquare] = index[capsq];
+ pieceList[them][capture][index[lastSquare]] = lastSquare;
+ pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
- // Update material hash key
+ // Update hash keys
+ k ^= zobrist[them][capture][capsq];
st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]];
- // Update piece list, move the last piece at index[capsq] position
- //
- // WARNING: This is a not perfectly revresible operation. When we
- // will reinsert the captured piece in undo_move() we will put it
- // at the end of the list and not in its original place, it means
- // index[] and pieceList[] are not guaranteed to be invariant to a
- // do_move() + undo_move() sequence.
- Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]];
- index[lastPieceSquare] = index[capsq];
- pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare;
- pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
+ // Update incremental scores
+ st->value -= pst(make_piece(them, capture), capsq);
// Reset rule 50 counter
st->rule50 = 0;
}
// Update hash key
- key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
+ k ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
// Reset en passant square
if (st->epSquare != SQ_NONE)
{
- key ^= zobEp[st->epSquare];
+ k ^= zobEp[st->epSquare];
st->epSquare = SQ_NONE;
}
if ( st->castleRights != CASTLES_NONE
&& (castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES)
{
- key ^= zobCastle[st->castleRights];
+ k ^= zobCastle[st->castleRights];
st->castleRights &= castleRightsMask[from] & castleRightsMask[to];
- key ^= zobCastle[st->castleRights];
+ k ^= zobCastle[st->castleRights];
}
// Prefetch TT access as soon as we know key is updated
- prefetch((char*)TT.first_entry(key));
+ prefetch((char*)TT.first_entry(k));
// Move the piece
Bitboard move_bb = make_move_bb(from, to);
do_move_bb(&occupied, move_bb);
board[to] = board[from];
- board[from] = PIECE_NONE;
+ board[from] = NO_PIECE;
- // Update piece lists, note that index[from] is not updated and
- // becomes stale. This works as long as index[] is accessed just
- // by known occupied squares.
+ // Update piece lists, index[from] is not updated and becomes stale. This
+ // works as long as index[] is accessed just by known occupied squares.
index[to] = index[from];
pieceList[us][pt][index[to]] = to;
- // If the moving piece was a pawn do some special extra work
+ // If the moving piece is a pawn do some special extra work
if (pt == PAWN)
{
- // Reset rule 50 draw counter
- st->rule50 = 0;
-
- // Update pawn hash key and prefetch in L1/L2 cache
- st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
-
- // Set en passant square, only if moved pawn can be captured
- if ((to ^ from) == 16)
+ // Set en-passant square, only if moved pawn can be captured
+ if ( (to ^ from) == 16
+ && (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(PAWN, them)))
{
- if (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(PAWN, them))
- {
- st->epSquare = Square((int(from) + int(to)) / 2);
- key ^= zobEp[st->epSquare];
- }
+ st->epSquare = Square((from + to) / 2);
+ k ^= zobEp[st->epSquare];
}
- if (pm) // promotion ?
+ if (is_promotion(m))
{
PieceType promotion = promotion_piece_type(m);
+ assert(relative_rank(us, to) == RANK_8);
assert(promotion >= KNIGHT && promotion <= QUEEN);
- // Insert promoted piece instead of pawn
+ // Replace the pawn with the promoted piece
clear_bit(&byTypeBB[PAWN], to);
set_bit(&byTypeBB[promotion], to);
board[to] = make_piece(us, promotion);
- // Update piece counts
- pieceCount[us][promotion]++;
- pieceCount[us][PAWN]--;
-
- // Update material key
- st->materialKey ^= zobrist[us][PAWN][pieceCount[us][PAWN]];
- st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]-1];
-
// Update piece lists, move the last pawn at index[to] position
// and shrink the list. Add a new promotion piece to the list.
- Square lastPawnSquare = pieceList[us][PAWN][pieceCount[us][PAWN]];
- index[lastPawnSquare] = index[to];
- pieceList[us][PAWN][index[lastPawnSquare]] = lastPawnSquare;
+ Square lastSquare = pieceList[us][PAWN][--pieceCount[us][PAWN]];
+ index[lastSquare] = index[to];
+ pieceList[us][PAWN][index[lastSquare]] = lastSquare;
pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE;
- index[to] = pieceCount[us][promotion] - 1;
+ index[to] = pieceCount[us][promotion];
pieceList[us][promotion][index[to]] = to;
- // Partially revert hash keys update
- key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to];
+ // Update hash keys
+ k ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to];
st->pawnKey ^= zobrist[us][PAWN][to];
+ st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]++]
+ ^ zobrist[us][PAWN][pieceCount[us][PAWN]];
- // Partially revert and update incremental scores
- st->value -= pst(make_piece(us, PAWN), to);
- st->value += pst(make_piece(us, promotion), to);
+ // Update incremental score
+ st->value += pst(make_piece(us, promotion), to)
+ - pst(make_piece(us, PAWN), to);
// Update material
st->npMaterial[us] += PieceValueMidgame[promotion];
}
+
+ // Update pawn hash key
+ st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+
+ // Reset rule 50 draw counter
+ st->rule50 = 0;
}
// Prefetch pawn and material hash tables
st->capturedType = capture;
// Update the key with the final value
- st->key = key;
+ st->key = k;
// Update checkers bitboard, piece must be already moved
- st->checkersBB = EmptyBoardBB;
+ st->checkersBB = 0;
if (moveIsCheck)
{
- if (ep | pm)
+ if (is_special(m))
st->checkersBB = attackers_to(king_square(them)) & pieces(us);
else
{
if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
{
if (pt != ROOK)
- st->checkersBB |= (attacks_from<ROOK>(king_square(them)) & pieces(ROOK, QUEEN, us));
+ st->checkersBB |= attacks_from<ROOK>(king_square(them)) & pieces(ROOK, QUEEN, us);
if (pt != BISHOP)
- st->checkersBB |= (attacks_from<BISHOP>(king_square(them)) & pieces(BISHOP, QUEEN, us));
+ st->checkersBB |= attacks_from<BISHOP>(king_square(them)) & pieces(BISHOP, QUEEN, us);
}
}
}
// Finish
- sideToMove = flip(sideToMove);
+ sideToMove = ~sideToMove;
st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
assert(pos_is_ok());
}
+/// 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.
+
+void Position::undo_move(Move m) {
+
+ assert(is_ok(m));
+
+ sideToMove = ~sideToMove;
+
+ if (is_castle(m))
+ {
+ do_castle_move<false>(m);
+ return;
+ }
+
+ Color us = sideToMove;
+ Color them = ~us;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece piece = piece_on(to);
+ PieceType pt = type_of(piece);
+ PieceType capture = st->capturedType;
+
+ assert(square_is_empty(from));
+ assert(color_of(piece) == us);
+ assert(capture != KING);
+
+ if (is_promotion(m))
+ {
+ PieceType promotion = promotion_piece_type(m);
+
+ assert(promotion == pt);
+ assert(relative_rank(us, to) == RANK_8);
+ assert(promotion >= KNIGHT && promotion <= QUEEN);
+
+ // Replace the promoted piece with the pawn
+ clear_bit(&byTypeBB[promotion], to);
+ set_bit(&byTypeBB[PAWN], to);
+ board[to] = make_piece(us, PAWN);
+
+ // Update piece lists, move the last promoted piece at index[to] position
+ // and shrink the list. Add a new pawn to the list.
+ Square lastSquare = pieceList[us][promotion][--pieceCount[us][promotion]];
+ index[lastSquare] = index[to];
+ pieceList[us][promotion][index[lastSquare]] = lastSquare;
+ pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE;
+ index[to] = pieceCount[us][PAWN]++;
+ pieceList[us][PAWN][index[to]] = to;
+
+ pt = PAWN;
+ }
+
+ // Put the piece back at the source square
+ Bitboard move_bb = make_move_bb(to, from);
+ do_move_bb(&byColorBB[us], move_bb);
+ do_move_bb(&byTypeBB[pt], move_bb);
+ do_move_bb(&occupied, move_bb);
+
+ board[from] = board[to];
+ board[to] = NO_PIECE;
+
+ // Update piece lists, index[to] is not updated and becomes stale. This
+ // works as long as index[] is accessed just by known occupied squares.
+ index[from] = index[to];
+ pieceList[us][pt][index[from]] = from;
+
+ if (capture)
+ {
+ Square capsq = to;
+
+ if (is_enpassant(m))
+ {
+ capsq -= pawn_push(us);
+
+ assert(pt == PAWN);
+ assert(to == st->previous->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(capsq) == NO_PIECE);
+ }
+
+ // Restore the captured piece
+ set_bit(&byColorBB[them], capsq);
+ set_bit(&byTypeBB[capture], capsq);
+ set_bit(&occupied, capsq);
+
+ board[capsq] = make_piece(them, capture);
+
+ // Update piece list, add a new captured piece in capsq square
+ index[capsq] = pieceCount[them][capture]++;
+ pieceList[them][capture][index[capsq]] = capsq;
+ }
+
+ // Finally point our state pointer back to the previous state
+ st = st->previous;
+
+ assert(pos_is_ok());
+}
+
+
/// Position::do_castle_move() is a private method used to do/undo a castling
/// move. Note that castling moves are encoded as "king captures friendly rook"
/// moves, for instance white short castling in a non-Chess960 game is encoded
Square kto, kfrom, rfrom, rto, kAfter, rAfter;
- Color us = side_to_move();
- Square kBefore = move_from(m);
- Square rBefore = move_to(m);
+ Color us = sideToMove;
+ Square kBefore = from_sq(m);
+ Square rBefore = to_sq(m);
// Find after-castle squares for king and rook
if (rBefore > kBefore) // O-O
// Update board
Piece king = make_piece(us, KING);
Piece rook = make_piece(us, ROOK);
- board[kfrom] = board[rfrom] = PIECE_NONE;
+ board[kfrom] = board[rfrom] = NO_PIECE;
board[kto] = king;
board[rto] = rook;
if (Do)
{
// Reset capture field
- st->capturedType = PIECE_TYPE_NONE;
+ st->capturedType = NO_PIECE_TYPE;
// Update incremental scores
st->value += pst_delta(king, kfrom, kto);
st->rule50 = 0;
// Update checkers BB
- st->checkersBB = attackers_to(king_square(flip(us))) & pieces(us);
+ st->checkersBB = attackers_to(king_square(~us)) & pieces(us);
// Finish
- sideToMove = flip(sideToMove);
+ sideToMove = ~sideToMove;
st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
}
else
}
-/// 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.
-
-void Position::undo_move(Move m) {
-
- assert(is_ok(m));
-
- sideToMove = flip(sideToMove);
-
- if (is_castle(m))
- {
- do_castle_move<false>(m);
- return;
- }
-
- Color us = side_to_move();
- Color them = flip(us);
- Square from = move_from(m);
- Square to = move_to(m);
- bool ep = is_enpassant(m);
- bool pm = is_promotion(m);
-
- PieceType pt = type_of(piece_on(to));
-
- assert(square_is_empty(from));
- assert(color_of(piece_on(to)) == us);
- assert(!pm || relative_rank(us, to) == RANK_8);
- assert(!ep || to == st->previous->epSquare);
- assert(!ep || relative_rank(us, to) == RANK_6);
- assert(!ep || piece_on(to) == make_piece(us, PAWN));
-
- if (pm) // promotion ?
- {
- PieceType promotion = promotion_piece_type(m);
- pt = PAWN;
-
- assert(promotion >= KNIGHT && promotion <= QUEEN);
- assert(piece_on(to) == make_piece(us, promotion));
-
- // Replace promoted piece with a pawn
- clear_bit(&byTypeBB[promotion], to);
- set_bit(&byTypeBB[PAWN], to);
-
- // Update piece counts
- pieceCount[us][promotion]--;
- pieceCount[us][PAWN]++;
-
- // Update piece list replacing promotion piece with a pawn
- Square lastPromotionSquare = pieceList[us][promotion][pieceCount[us][promotion]];
- index[lastPromotionSquare] = index[to];
- pieceList[us][promotion][index[lastPromotionSquare]] = lastPromotionSquare;
- pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE;
- index[to] = pieceCount[us][PAWN] - 1;
- pieceList[us][PAWN][index[to]] = to;
- }
-
- // Put the piece back at the source square
- Bitboard move_bb = make_move_bb(to, from);
- do_move_bb(&byColorBB[us], move_bb);
- do_move_bb(&byTypeBB[pt], move_bb);
- do_move_bb(&occupied, move_bb);
-
- board[from] = make_piece(us, pt);
- board[to] = PIECE_NONE;
-
- // Update piece list
- index[from] = index[to];
- pieceList[us][pt][index[from]] = from;
-
- if (st->capturedType)
- {
- Square capsq = to;
-
- if (ep)
- capsq = to - pawn_push(us);
-
- assert(st->capturedType != KING);
- assert(!ep || square_is_empty(capsq));
-
- // Restore the captured piece
- set_bit(&byColorBB[them], capsq);
- set_bit(&byTypeBB[st->capturedType], capsq);
- set_bit(&occupied, capsq);
-
- board[capsq] = make_piece(them, st->capturedType);
-
- // Update piece count
- pieceCount[them][st->capturedType]++;
-
- // Update piece list, add a new captured piece in capsq square
- index[capsq] = pieceCount[them][st->capturedType] - 1;
- pieceList[them][st->capturedType][index[capsq]] = capsq;
- }
-
- // Finally point our state pointer back to the previous state
- st = st->previous;
-
- assert(pos_is_ok());
-}
-
-
/// Position::do_null_move() is used to do/undo a "null move": It flips the side
/// to move and updates the hash key without executing any move on the board.
template<bool Do>
dst->rule50 = src->rule50;
dst->pliesFromNull = src->pliesFromNull;
- sideToMove = flip(sideToMove);
+ sideToMove = ~sideToMove;
if (Do)
{
assert(is_ok(m));
- Square from = move_from(m);
- Square to = move_to(m);
+ Square from = from_sq(m);
+ Square to = to_sq(m);
// Early return if SEE cannot be negative because captured piece value
// is not less then capturing one. Note that king moves always return
if (is_castle(m))
return 0;
- from = move_from(m);
- to = move_to(m);
+ from = from_sq(m);
+ to = to_sq(m);
capturedType = type_of(piece_on(to));
occ = occupied_squares();
// Handle en passant moves
- if (st->epSquare == to && type_of(piece_on(from)) == PAWN)
+ if (is_enpassant(m))
{
- Square capQq = to - pawn_push(side_to_move());
+ Square capQq = to - pawn_push(sideToMove);
- assert(capturedType == PIECE_TYPE_NONE);
+ assert(!capturedType);
assert(type_of(piece_on(capQq)) == PAWN);
// Remove the captured pawn
attackers = attackers_to(to, occ);
// If the opponent has no attackers we are finished
- stm = flip(color_of(piece_on(from)));
+ stm = ~color_of(piece_on(from));
stmAttackers = attackers & pieces(stm);
if (!stmAttackers)
return PieceValueMidgame[capturedType];
// Remember the value of the capturing piece, and change the side to
// move before beginning the next iteration.
capturedType = pt;
- stm = flip(stm);
+ stm = ~stm;
stmAttackers = attackers & pieces(stm);
// Stop before processing a king capture
// 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] = Min(-swapList[slIndex], swapList[slIndex-1]);
+ swapList[slIndex-1] = std::min(-swapList[slIndex], swapList[slIndex-1]);
return swapList[0];
}
for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
{
- board[sq] = PIECE_NONE;
+ board[sq] = NO_PIECE;
castleRightsMask[sq] = ALL_CASTLES;
}
sideToMove = WHITE;
if (ep_square() != SQ_NONE)
result ^= zobEp[ep_square()];
- if (side_to_move() == BLACK)
+ if (sideToMove == BLACK)
result ^= zobSideToMove;
return result;
result += pst(make_piece(c, pt), pop_1st_bit(&b));
}
- result += (side_to_move() == WHITE ? TempoValue / 2 : -TempoValue / 2);
+ result += (sideToMove == WHITE ? TempoValue / 2 : -TempoValue / 2);
return result;
}
return true;
// Draw by the 50 moves rule?
- if (st->rule50 > 99 && !is_mate())
+ if (st->rule50 > 99 && (!in_check() || MoveList<MV_LEGAL>(*this).size()))
return true;
// Draw by repetition?
if (!SkipRepetition)
{
- int i = 4, e = Min(st->rule50, st->pliesFromNull);
+ int i = 4, e = std::min(st->rule50, st->pliesFromNull);
if (i <= e)
{
template bool Position::is_draw<true>() const;
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated.
-
-bool Position::is_mate() const {
-
- return in_check() && !MoveList<MV_LEGAL>(*this).size();
-}
-
-
/// Position::init() is a static member function which 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
zobSideToMove = rk.rand<Key>();
zobExclusion = rk.rand<Key>();
- for (Piece p = WP; p <= WK; p++)
+ for (Piece p = W_PAWN; p <= W_KING; p++)
{
Score ps = make_score(PieceValueMidgame[p], PieceValueEndgame[p]);
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
pieceSquareTable[p][s] = ps + PSQT[p][s];
- pieceSquareTable[p+8][flip(s)] = -pieceSquareTable[p][s];
+ pieceSquareTable[p+8][~s] = -pieceSquareTable[p][s];
}
}
}
// Board
for (Square s = SQ_A1; s <= SQ_H8; s++)
if (!pos.square_is_empty(s))
- put_piece(Piece(pos.piece_on(s) ^ 8), flip(s));
+ put_piece(Piece(pos.piece_on(s) ^ 8), ~s);
// Side to move
- sideToMove = flip(pos.side_to_move());
+ sideToMove = ~pos.side_to_move();
// Castling rights
if (pos.can_castle(WHITE_OO))
- set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OO)));
+ set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OO));
if (pos.can_castle(WHITE_OOO))
- set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OOO)));
+ set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OOO));
if (pos.can_castle(BLACK_OO))
- set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OO)));
+ set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OO));
if (pos.can_castle(BLACK_OOO))
- set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OOO)));
+ set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OOO));
// En passant square
if (pos.st->epSquare != SQ_NONE)
- st->epSquare = flip(pos.st->epSquare);
+ st->epSquare = ~pos.st->epSquare;
// Checkers
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
+ st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
// Hash keys
st->key = compute_key();
if (failedStep) *failedStep = 1;
// Side to move OK?
- if (side_to_move() != WHITE && side_to_move() != BLACK)
+ if (sideToMove != WHITE && sideToMove != BLACK)
return false;
// Are the king squares in the position correct?
if (failedStep) (*failedStep)++;
- if (piece_on(king_square(WHITE)) != WK)
+ if (piece_on(king_square(WHITE)) != W_KING)
return false;
if (failedStep) (*failedStep)++;
- if (piece_on(king_square(BLACK)) != BK)
+ if (piece_on(king_square(BLACK)) != B_KING)
return false;
// Do both sides have exactly one king?
if (failedStep) (*failedStep)++;
if (debugKingCapture)
{
- Color us = side_to_move();
- Color them = flip(us);
+ Color us = sideToMove;
+ Color them = ~us;
Square ksq = king_square(them);
if (attackers_to(ksq) & pieces(us))
return false;
// Is there more than 2 checkers?
if (failedStep) (*failedStep)++;
- if (debugCheckerCount && count_1s<CNT32>(st->checkersBB) > 2)
+ if (debugCheckerCount && popcount<Full>(st->checkersBB) > 2)
return false;
// Bitboards OK?
if (debugBitboards)
{
// The intersection of the white and black pieces must be empty
- if ((pieces(WHITE) & pieces(BLACK)) != EmptyBoardBB)
+ if (!(pieces(WHITE) & pieces(BLACK)))
return false;
// The union of the white and black pieces must be equal to all
{
// The en passant square must be on rank 6, from the point of view of the
// side to move.
- if (relative_rank(side_to_move(), ep_square()) != RANK_6)
+ if (relative_rank(sideToMove, ep_square()) != RANK_6)
return false;
}
if (debugPieceCounts)
for (Color c = WHITE; c <= BLACK; c++)
for (PieceType pt = PAWN; pt <= KING; pt++)
- if (pieceCount[c][pt] != count_1s<CNT32>(pieces(pt, c)))
+ if (pieceCount[c][pt] != popcount<Full>(pieces(pt, c)))
return false;
if (failedStep) (*failedStep)++;
if (!can_castle(f))
continue;
- Piece rook = (f & (WHITE_OO | WHITE_OOO) ? WR : BR);
+ Piece rook = (f & (WHITE_OO | WHITE_OOO) ? W_ROOK : B_ROOK);
if ( castleRightsMask[castleRookSquare[f]] != (ALL_CASTLES ^ f)
|| piece_on(castleRookSquare[f]) != rook)
projects / stockfish / blobdiff