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DroidFish: Updated stockfish engine to version 3.

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This commit is contained in:
Peter Osterlund
2013-05-03 17:03:42 +00:00
parent 3f55b61865
commit 34b9fd139f
42 changed files with 2092 additions and 2383 deletions
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548
DroidFish/jni/stockfish/position.cpp
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@@ -1,7 +1,7 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -19,6 +19,7 @@
#include <cassert>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <sstream>
#include <algorithm>
@@ -40,16 +41,16 @@ static const string PieceToChar(" PNBRQK pnbrqk");
CACHE_LINE_ALIGNMENT
Score pieceSquareTable[16][64]; // [piece][square]
Value PieceValue[2][18] = { // [Mg / Eg][piece / pieceType]
Score pieceSquareTable[PIECE_NB][SQUARE_NB];
Value PieceValue[PHASE_NB][PIECE_NB] = {
{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
namespace Zobrist {
Key psq[2][8][64]; // [color][pieceType][square / piece count]
Key enpassant[8]; // [file]
Key castle[16]; // [castleRight]
Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
Key enpassant[FILE_NB];
Key castle[CASTLE_RIGHT_NB];
Key side;
Key exclusion;
@@ -86,10 +87,10 @@ void init() {
for (PieceType pt = PAWN; pt <= KING; pt++)
{
PieceValue[Mg][make_piece(BLACK, pt)] = PieceValue[Mg][pt];
PieceValue[Eg][make_piece(BLACK, pt)] = PieceValue[Eg][pt];
PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt];
PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt];
Score v = make_score(PieceValue[Mg][pt], PieceValue[Eg][pt]);
Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]);
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
@@ -172,11 +173,11 @@ Position& Position::operator=(const Position& pos) {
}
/// Position::from_fen() initializes the position object with the given FEN
/// string. This function is not very robust - make sure that input FENs are
/// correct (this is assumed to be the responsibility of the GUI).
/// Position::set() initializes the position object with the given FEN string.
/// This function is not very robust - make sure that input FENs are correct,
/// this is assumed to be the responsibility of the GUI.
void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) {
void Position::set(const string& fenStr, bool isChess960, Thread* th) {
/*
A FEN string defines a particular position using only the ASCII character set.
@@ -214,13 +215,13 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) {
char col, row, token;
size_t p;
Square sq = SQ_A8;
std::istringstream fen(fenStr);
std::istringstream ss(fenStr);
clear();
fen >> std::noskipws;
ss >> std::noskipws;
// 1. Piece placement
while ((fen >> token) && !isspace(token))
while ((ss >> token) && !isspace(token))
{
if (isdigit(token))
sq += Square(token - '0'); // Advance the given number of files
@@ -236,16 +237,16 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) {
}
// 2. Active color
fen >> token;
ss >> token;
sideToMove = (token == 'w' ? WHITE : BLACK);
fen >> token;
ss >> token;
// 3. Castling availability. Compatible with 3 standards: Normal FEN standard,
// Shredder-FEN that uses the letters of the columns on which the rooks began
// the game instead of KQkq and also X-FEN standard that, in case of Chess960,
// if an inner rook is associated with the castling right, the castling tag is
// replaced by the file letter of the involved rook, as for the Shredder-FEN.
while ((fen >> token) && !isspace(token))
while ((ss >> token) && !isspace(token))
{
Square rsq;
Color c = islower(token) ? BLACK : WHITE;
@@ -268,8 +269,8 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) {
}
// 4. En passant square. Ignore if no pawn capture is possible
if ( ((fen >> col) && (col >= 'a' && col <= 'h'))
&& ((fen >> row) && (row == '3' || row == '6')))
if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
&& ((ss >> row) && (row == '3' || row == '6')))
{
st->epSquare = File(col - 'a') | Rank(row - '1');
@@ -278,11 +279,11 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) {
}
// 5-6. Halfmove clock and fullmove number
fen >> std::skipws >> st->rule50 >> startPosPly;
ss >> std::skipws >> st->rule50 >> gamePly;
// Convert from fullmove starting from 1 to ply starting from 0,
// handle also common incorrect FEN with fullmove = 0.
startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK);
st->key = compute_key();
st->pawnKey = compute_pawn_key();
@@ -325,71 +326,64 @@ void Position::set_castle_right(Color c, Square rfrom) {
}
/// Position::to_fen() returns a FEN representation of the position. In case
/// Position::fen() returns a FEN representation of the position. In case
/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function.
const string Position::to_fen() const {
const string Position::fen() const {
std::ostringstream fen;
Square sq;
int emptyCnt;
std::ostringstream ss;
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
{
emptyCnt = 0;
for (File file = FILE_A; file <= FILE_H; file++)
{
sq = file | rank;
Square sq = file | rank;
if (is_empty(sq))
emptyCnt++;
else
{
if (emptyCnt > 0)
{
fen << emptyCnt;
emptyCnt = 0;
}
fen << PieceToChar[piece_on(sq)];
int emptyCnt = 1;
for ( ; file < FILE_H && is_empty(sq++); file++)
emptyCnt++;
ss << emptyCnt;
}
else
ss << PieceToChar[piece_on(sq)];
}
if (emptyCnt > 0)
fen << emptyCnt;
if (rank > RANK_1)
fen << '/';
ss << '/';
}
fen << (sideToMove == WHITE ? " w " : " b ");
ss << (sideToMove == WHITE ? " w " : " b ");
if (can_castle(WHITE_OO))
fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE))))) : 'K');
ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K');
if (can_castle(WHITE_OOO))
fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE))))) : 'Q');
ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q');
if (can_castle(BLACK_OO))
fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE))) : 'k');
ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k');
if (can_castle(BLACK_OOO))
fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE))) : 'q');
ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q');
if (st->castleRights == CASTLES_NONE)
fen << '-';
ss << '-';
fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
<< st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
<< st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
return fen.str();
return ss.str();
}
/// Position::print() prints an ASCII representation of the position to
/// the standard output. If a move is given then also the san is printed.
/// Position::pretty() returns an ASCII representation of the position to be
/// printed to the standard output together with the move's san notation.
void Position::print(Move move) const {
const string Position::pretty(Move move) const {
const string dottedLine = "\n+---+---+---+---+---+---+---+---+";
const string twoRows = dottedLine + "\n| | . | | . | | . | | . |"
@@ -397,19 +391,27 @@ void Position::print(Move move) const {
string brd = twoRows + twoRows + twoRows + twoRows + dottedLine;
sync_cout;
std::ostringstream ss;
if (move)
{
Position p(*this);
cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move);
}
ss << "\nMove: " << (sideToMove == BLACK ? ".." : "")
<< move_to_san(*const_cast<Position*>(this), move);
for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
if (piece_on(sq) != NO_PIECE)
brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)];
cout << brd << "\nFen is: " << to_fen() << "\nKey is: " << st->key << sync_endl;
ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase
<< std::setfill('0') << std::setw(16) << st->key << "\nCheckers: ";
for (Bitboard b = checkers(); b; )
ss << square_to_string(pop_lsb(&b)) << " ";
ss << "\nLegal moves: ";
for (MoveList<LEGAL> ml(*this); !ml.end(); ++ml)
ss << move_to_san(*const_cast<Position*>(this), ml.move()) << " ";
return ss.str();
}
@@ -475,37 +477,6 @@ Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) {
}
/// Position::move_attacks_square() tests whether a move from the current
/// position attacks a given square.
bool Position::move_attacks_square(Move m, Square s) const {
assert(is_ok(m));
assert(is_ok(s));
Bitboard occ, xray;
Square from = from_sq(m);
Square to = to_sq(m);
Piece piece = piece_moved(m);
assert(!is_empty(from));
// Update occupancy as if the piece is moving
occ = pieces() ^ from ^ to;
// The piece moved in 'to' attacks the square 's' ?
if (attacks_from(piece, to, occ) & s)
return true;
// Scan for possible X-ray attackers behind the moved piece
xray = (attacks_bb< ROOK>(s, occ) & pieces(color_of(piece), QUEEN, ROOK))
| (attacks_bb<BISHOP>(s, occ) & pieces(color_of(piece), QUEEN, BISHOP));
// Verify attackers are triggered by our move and not already existing
return xray && (xray ^ (xray & attacks_from<QUEEN>(s)));
}
/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
@@ -553,20 +524,6 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
}
/// 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.
bool Position::move_is_legal(const Move m) const {
for (MoveList<LEGAL> ml(*this); !ml.end(); ++ml)
if (ml.move() == m)
return true;
return false;
}
/// Position::is_pseudo_legal() takes a random move and tests whether the move
/// is pseudo legal. It is used to validate moves from TT that can be corrupted
/// due to SMP concurrent access or hash position key aliasing.
@@ -574,14 +531,13 @@ bool Position::move_is_legal(const Move m) const {
bool Position::is_pseudo_legal(const Move m) const {
Color us = sideToMove;
Color them = ~sideToMove;
Square from = from_sq(m);
Square to = to_sq(m);
Piece pc = piece_moved(m);
// Use a slower but simpler function for uncommon cases
if (type_of(m) != NORMAL)
return move_is_legal(m);
return MoveList<LEGAL>(*this).contains(m);
// Is not a promotion, so promotion piece must be empty
if (promotion_type(m) - 2 != NO_PIECE_TYPE)
@@ -593,7 +549,7 @@ bool Position::is_pseudo_legal(const Move m) const {
return false;
// The destination square cannot be occupied by a friendly piece
if (color_of(piece_on(to)) == us)
if (piece_on(to) != NO_PIECE && color_of(piece_on(to)) == us)
return false;
// Handle the special case of a pawn move
@@ -619,7 +575,7 @@ bool Position::is_pseudo_legal(const Move m) const {
case DELTA_SE:
// Capture. The destination square must be occupied by an enemy
// piece (en passant captures was handled earlier).
if (color_of(piece_on(to)) != them)
if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us)
return false;
// From and to files must be one file apart, avoids a7h5
@@ -664,18 +620,16 @@ bool Position::is_pseudo_legal(const Move m) const {
// Evasions generator already takes care to avoid some kind of illegal moves
// and pl_move_is_legal() relies on this. So we have to take care that the
// same kind of moves are filtered out here.
if (in_check())
if (checkers())
{
if (type_of(pc) != KING)
{
Bitboard b = checkers();
Square checksq = pop_lsb(&b);
if (b) // 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(checksq, king_square(us)) | checkers()) & to))
if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to))
return false;
}
// In case of king moves under check we have to remove king so to catch
@@ -720,15 +674,16 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
Color us = sideToMove;
Square ksq = king_square(~us);
// Promotion with check ?
if (type_of(m) == PROMOTION)
switch (type_of(m))
{
case PROMOTION:
return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq;
// En passant capture with check ? We have already handled the case
// of direct checks and ordinary discovered check, the only case we
// need to handle is the unusual case of a discovered check through
// the captured pawn.
if (type_of(m) == ENPASSANT)
case ENPASSANT:
{
Square capsq = file_of(to) | rank_of(from);
Bitboard b = (pieces() ^ from ^ capsq) | to;
@@ -736,9 +691,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK))
| (attacks_bb<BISHOP>(ksq, b) & pieces(us, QUEEN, BISHOP));
}
// Castling with check ?
if (type_of(m) == CASTLE)
case CASTLE:
{
Square kfrom = from;
Square rfrom = to; // 'King captures the rook' notation
@@ -748,8 +701,10 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
return attacks_bb<ROOK>(rto, b) & ksq;
}
return false;
default:
assert(false);
return false;
}
}
@@ -772,9 +727,9 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
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.
memcpy(&newSt, st, sizeof(ReducedStateInfo));
// which are going to be recalculated from scratch anyway, then switch our state
// pointer to point to the new, ready to be updated, state.
memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
newSt.previous = st;
st = &newSt;
@@ -782,18 +737,12 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
// Update side to move
k ^= Zobrist::side;
// Increment the 50 moves rule draw counter. Resetting it to zero in the
// case of a capture or a pawn move is taken care of later.
// Increment ply counters.In particular rule50 will be later reset it to zero
// in case of a capture or a pawn move.
gamePly++;
st->rule50++;
st->pliesFromNull++;
if (type_of(m) == CASTLE)
{
st->key = k;
do_castle_move<true>(m);
return;
}
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
@@ -803,9 +752,25 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
PieceType capture = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
assert(color_of(piece) == us);
assert(color_of(piece_on(to)) != us);
assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE);
assert(capture != KING);
if (type_of(m) == CASTLE)
{
assert(piece == make_piece(us, KING));
bool kingSide = to > from;
Square rfrom = to; // Castle is encoded as "king captures friendly rook"
Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
capture = NO_PIECE_TYPE;
do_castle(from, to, rfrom, rto);
st->psqScore += psq_delta(make_piece(us, ROOK), rfrom, rto);
k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
}
if (capture)
{
Square capsq = to;
@@ -830,7 +795,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
}
else
st->npMaterial[them] -= PieceValue[Mg][capture];
st->npMaterial[them] -= PieceValue[MG][capture];
// Remove the captured piece
byTypeBB[ALL_PIECES] ^= capsq;
@@ -840,7 +805,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
// 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
// WARNING: This is a not reversible 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.
@@ -849,9 +814,10 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
pieceList[them][capture][index[lastSquare]] = lastSquare;
pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
// Update hash keys
// Update material hash key and prefetch access to materialTable
k ^= Zobrist::psq[them][capture][capsq];
st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]];
prefetch((char*)thisThread->materialTable[st->materialKey]);
// Update incremental scores
st->psqScore -= pieceSquareTable[make_piece(them, capture)][capsq];
@@ -878,22 +844,25 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
st->castleRights &= ~cr;
}
// Prefetch TT access as soon as we know key is updated
// Prefetch TT access as soon as we know the new hash key
prefetch((char*)TT.first_entry(k));
// Move the piece
Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
byTypeBB[ALL_PIECES] ^= from_to_bb;
byTypeBB[pt] ^= from_to_bb;
byColorBB[us] ^= from_to_bb;
// Move the piece. The tricky Chess960 castle is handled earlier
if (type_of(m) != CASTLE)
{
Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
byTypeBB[ALL_PIECES] ^= from_to_bb;
byTypeBB[pt] ^= from_to_bb;
byColorBB[us] ^= from_to_bb;
board[to] = board[from];
board[from] = NO_PIECE;
board[from] = NO_PIECE;
board[to] = piece;
// 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;
// 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 is a pawn do some special extra work
if (pt == PAWN)
@@ -938,20 +907,17 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
- pieceSquareTable[make_piece(us, PAWN)][to];
// Update material
st->npMaterial[us] += PieceValue[Mg][promotion];
st->npMaterial[us] += PieceValue[MG][promotion];
}
// Update pawn hash key
// Update pawn hash key and prefetch access to pawnsTable
st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to];
prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
// Reset rule 50 draw counter
st->rule50 = 0;
}
// Prefetch pawn and material hash tables
prefetch((char*)thisThread->pawnTable.entries[st->pawnKey]);
prefetch((char*)thisThread->materialTable.entries[st->materialKey]);
// Update incremental scores
st->psqScore += psq_delta(piece, from, to);
@@ -1001,22 +967,14 @@ void Position::undo_move(Move m) {
sideToMove = ~sideToMove;
if (type_of(m) == CASTLE)
{
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 pt = type_of(piece_on(to));
PieceType capture = st->capturedType;
assert(is_empty(from));
assert(color_of(piece) == us);
assert(is_empty(from) || type_of(m) == CASTLE);
assert(capture != KING);
if (type_of(m) == PROMOTION)
@@ -1044,19 +1002,32 @@ void Position::undo_move(Move m) {
pt = PAWN;
}
// Put the piece back at the source square
Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
byTypeBB[ALL_PIECES] ^= from_to_bb;
byTypeBB[pt] ^= from_to_bb;
byColorBB[us] ^= from_to_bb;
if (type_of(m) == CASTLE)
{
bool kingSide = to > from;
Square rfrom = to; // Castle is encoded as "king captures friendly rook"
Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
capture = NO_PIECE_TYPE;
pt = KING;
do_castle(to, from, rto, rfrom);
}
else
{
// Put the piece back at the source square
Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
byTypeBB[ALL_PIECES] ^= from_to_bb;
byTypeBB[pt] ^= from_to_bb;
byColorBB[us] ^= from_to_bb;
board[from] = board[to];
board[to] = NO_PIECE;
board[to] = NO_PIECE;
board[from] = make_piece(us, pt);
// 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;
// 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)
{
@@ -1086,49 +1057,18 @@ void Position::undo_move(Move m) {
// Finally point our state pointer back to the previous state
st = st->previous;
gamePly--;
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
/// as e1h1.
template<bool Do>
void Position::do_castle_move(Move m) {
/// Position::do_castle() is a helper used to do/undo a castling move. This
/// is a bit tricky, especially in Chess960.
assert(is_ok(m));
assert(type_of(m) == CASTLE);
Square kto, kfrom, rfrom, rto, kAfter, rAfter;
void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) {
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
{
kAfter = relative_square(us, SQ_G1);
rAfter = relative_square(us, SQ_F1);
}
else // O-O-O
{
kAfter = relative_square(us, SQ_C1);
rAfter = relative_square(us, SQ_D1);
}
kfrom = Do ? kBefore : kAfter;
rfrom = Do ? rBefore : rAfter;
kto = Do ? kAfter : kBefore;
rto = Do ? rAfter : rBefore;
assert(piece_on(kfrom) == make_piece(us, KING));
assert(piece_on(rfrom) == make_piece(us, ROOK));
// Move the pieces, with some care; in chess960 could be kto == rfrom
Bitboard k_from_to_bb = SquareBB[kfrom] ^ SquareBB[kto];
Bitboard r_from_to_bb = SquareBB[rfrom] ^ SquareBB[rto];
byTypeBB[KING] ^= k_from_to_bb;
@@ -1136,105 +1076,63 @@ void Position::do_castle_move(Move m) {
byTypeBB[ALL_PIECES] ^= k_from_to_bb ^ r_from_to_bb;
byColorBB[us] ^= k_from_to_bb ^ r_from_to_bb;
// Update board
Piece king = make_piece(us, KING);
Piece rook = make_piece(us, ROOK);
// Could be from == to, so first set NO_PIECE then KING and ROOK
board[kfrom] = board[rfrom] = NO_PIECE;
board[kto] = king;
board[rto] = rook;
board[kto] = make_piece(us, KING);
board[rto] = make_piece(us, ROOK);
// Update piece lists
pieceList[us][KING][index[kfrom]] = kto;
pieceList[us][ROOK][index[rfrom]] = rto;
int tmp = index[rfrom]; // In Chess960 could be kto == rfrom
index[kto] = index[kfrom];
index[rto] = tmp;
if (Do)
{
// Reset capture field
st->capturedType = NO_PIECE_TYPE;
// Update incremental scores
st->psqScore += psq_delta(king, kfrom, kto);
st->psqScore += psq_delta(rook, rfrom, rto);
// Update hash key
st->key ^= Zobrist::psq[us][KING][kfrom] ^ Zobrist::psq[us][KING][kto];
st->key ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
// Clear en passant square
if (st->epSquare != SQ_NONE)
{
st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
st->epSquare = SQ_NONE;
}
// Update castling rights
st->key ^= Zobrist::castle[st->castleRights & castleRightsMask[kfrom]];
st->castleRights &= ~castleRightsMask[kfrom];
// Update checkers BB
st->checkersBB = attackers_to(king_square(~us)) & pieces(us);
sideToMove = ~sideToMove;
}
else
// Undo: point our state pointer back to the previous state
st = st->previous;
assert(pos_is_ok());
// Could be kfrom == rto, so use a 'tmp' variable
int tmp = index[kfrom];
index[rto] = index[rfrom];
index[kto] = tmp;
pieceList[us][KING][index[kto]] = kto;
pieceList[us][ROOK][index[rto]] = rto;
}
/// 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>
void Position::do_null_move(StateInfo& backupSt) {
/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips
/// the side to move without executing any move on the board.
assert(!in_check());
void Position::do_null_move(StateInfo& newSt) {
// Back up the information necessary to undo the null move to the supplied
// StateInfo object. Note that differently from normal case here backupSt
// is actually used as a backup storage not as the new state. This reduces
// the number of fields to be copied.
StateInfo* src = Do ? st : &backupSt;
StateInfo* dst = Do ? &backupSt : st;
assert(!checkers());
dst->key = src->key;
dst->epSquare = src->epSquare;
dst->psqScore = src->psqScore;
dst->rule50 = src->rule50;
dst->pliesFromNull = src->pliesFromNull;
memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
newSt.previous = st;
st = &newSt;
if (st->epSquare != SQ_NONE)
{
st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
st->epSquare = SQ_NONE;
}
st->key ^= Zobrist::side;
prefetch((char*)TT.first_entry(st->key));
st->rule50++;
st->pliesFromNull = 0;
sideToMove = ~sideToMove;
if (Do)
{
if (st->epSquare != SQ_NONE)
st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
st->key ^= Zobrist::side;
prefetch((char*)TT.first_entry(st->key));
st->epSquare = SQ_NONE;
st->rule50++;
st->pliesFromNull = 0;
}
assert(pos_is_ok());
}
// Explicit template instantiations
template void Position::do_null_move<false>(StateInfo& backupSt);
template void Position::do_null_move<true>(StateInfo& backupSt);
void Position::undo_null_move() {
assert(!checkers());
st = st->previous;
sideToMove = ~sideToMove;
}
/// 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
/// 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.
/// material gain or loss resulting from a move. Parameter 'asymmThreshold' takes
/// tempi into account. If the side who initiated the capturing sequence does the
/// last capture, he loses a tempo and if the result is below 'asymmThreshold'
/// the capturing sequence is considered bad.
int Position::see_sign(Move m) const {
@@ -1243,13 +1141,13 @@ int Position::see_sign(Move m) const {
// Early return if SEE cannot be negative because captured piece value
// is not less then capturing one. Note that king moves always return
// here because king midgame value is set to 0.
if (PieceValue[Mg][piece_on(to_sq(m))] >= PieceValue[Mg][piece_moved(m)])
if (PieceValue[MG][piece_on(to_sq(m))] >= PieceValue[MG][piece_moved(m)])
return 1;
return see(m);
}
int Position::see(Move m) const {
int Position::see(Move m, int asymmThreshold) const {
Square from, to;
Bitboard occupied, attackers, stmAttackers;
@@ -1290,7 +1188,7 @@ int Position::see(Move m) const {
stm = ~color_of(piece_on(from));
stmAttackers = attackers & pieces(stm);
if (!stmAttackers)
return PieceValue[Mg][captured];
return PieceValue[MG][captured];
// The destination square is defended, which makes things rather more
// difficult to compute. We proceed by building up a "swap list" containing
@@ -1298,14 +1196,14 @@ int Position::see(Move m) const {
// destination square, where the sides alternately capture, and always
// capture with the least valuable piece. After each capture, we look for
// new X-ray attacks from behind the capturing piece.
swapList[0] = PieceValue[Mg][captured];
swapList[0] = PieceValue[MG][captured];
captured = type_of(piece_on(from));
do {
assert(slIndex < 32);
// Add the new entry to the swap list
swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[Mg][captured];
swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
slIndex++;
// Locate and remove from 'occupied' the next least valuable attacker
@@ -1326,6 +1224,15 @@ int Position::see(Move m) const {
} while (stmAttackers);
// If we are doing asymmetric SEE evaluation and the same side does the first
// and the last capture, he loses a tempo and gain must be at least worth
// 'asymmThreshold', otherwise we replace the score with a very low value,
// before negamaxing.
if (asymmThreshold)
for (int i = 0; i < slIndex; i += 2)
if (swapList[i] < asymmThreshold)
swapList[i] = - QueenValueMg * 16;
// 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)
@@ -1347,9 +1254,6 @@ void Position::clear() {
for (int i = 0; i < 8; i++)
for (int j = 0; j < 16; j++)
pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
board[sq] = NO_PIECE;
}
@@ -1463,7 +1367,7 @@ Value Position::compute_non_pawn_material(Color c) const {
Value value = VALUE_ZERO;
for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
value += piece_count(c, pt) * PieceValue[Mg][pt];
value += piece_count(c, pt) * PieceValue[MG][pt];
return value;
}
@@ -1472,7 +1376,6 @@ Value Position::compute_non_pawn_material(Color c) const {
/// 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.
template<bool SkipRepetition>
bool Position::is_draw() const {
// Draw by material?
@@ -1481,37 +1384,30 @@ bool Position::is_draw() const {
return true;
// Draw by the 50 moves rule?
if (st->rule50 > 99 && (!in_check() || MoveList<LEGAL>(*this).size()))
if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
// Draw by repetition?
if (!SkipRepetition)
int i = 4, e = std::min(st->rule50, st->pliesFromNull);
if (i <= e)
{
int i = 4, e = std::min(st->rule50, st->pliesFromNull);
StateInfo* stp = st->previous->previous;
if (i <= e)
{
StateInfo* stp = st->previous->previous;
do {
stp = stp->previous->previous;
do {
stp = stp->previous->previous;
if (stp->key == st->key)
return true;
if (stp->key == st->key)
return true;
i += 2;
i +=2;
} while (i <= e);
}
} while (i <= e);
}
return false;
}
// Explicit template instantiations
template bool Position::is_draw<false>() const;
template bool Position::is_draw<true>() const;
/// Position::flip() flips position with the white and black sides reversed. This
/// is only useful for debugging especially for finding evaluation symmetry bugs.
@@ -1526,7 +1422,7 @@ void Position::flip() {
thisThread = pos.this_thread();
nodes = pos.nodes_searched();
chess960 = pos.is_chess960();
startPosPly = pos.startpos_ply_counter();
gamePly = pos.game_ply();
for (Square s = SQ_A1; s <= SQ_H8; s++)
if (!pos.is_empty(s))
@@ -1593,7 +1489,7 @@ bool Position::pos_is_ok(int* failedStep) const {
if ((*step)++, debugKingCount)
{
int kingCount[2] = {};
int kingCount[COLOR_NB] = {};
for (Square s = SQ_A1; s <= SQ_H8; s++)
if (type_of(piece_on(s)) == KING)