/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ 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
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
- Glaurung is distributed in the hope that it will be useful,
+ Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
////
#include <cassert>
-#include <iostream>
+#include <cstring>
#include <fstream>
+#include <iostream>
+#include "bitcount.h"
#include "mersenne.h"
#include "movegen.h"
#include "movepick.h"
#include "position.h"
#include "psqtab.h"
+#include "san.h"
+#include "tt.h"
#include "ucioption.h"
+using std::string;
+
////
//// Variables
////
-int Position::castleRightsMask[64];
-
Key Position::zobrist[2][8][64];
Key Position::zobEp[64];
Key Position::zobCastle[16];
Key Position::zobMaterial[2][8][16];
Key Position::zobSideToMove;
+Key Position::zobExclusion;
-Value Position::MgPieceSquareTable[16][64];
-Value Position::EgPieceSquareTable[16][64];
+Score Position::PieceSquareTable[16][64];
+static bool RequestPending = false;
-////
-//// Functions
-////
/// Constructors
-Position::Position(const Position &pos) {
- copy(pos);
+CheckInfo::CheckInfo(const Position& pos) {
+
+ Color us = pos.side_to_move();
+ Color them = opposite_color(us);
+
+ ksq = pos.king_square(them);
+ dcCandidates = pos.discovered_check_candidates(us);
+
+ checkSq[PAWN] = pos.attacks_from<PAWN>(ksq, them);
+ checkSq[KNIGHT] = pos.attacks_from<KNIGHT>(ksq);
+ checkSq[BISHOP] = pos.attacks_from<BISHOP>(ksq);
+ checkSq[ROOK] = pos.attacks_from<ROOK>(ksq);
+ checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK];
+ checkSq[KING] = EmptyBoardBB;
+}
+
+
+/// Position c'tors. Here we always create a slower but safer copy of
+/// the original position or the FEN string, we want the new born Position
+/// object do not depend on any external data. Instead if we know what we
+/// are doing and we need speed we can create a position with default
+/// c'tor Position() and then use just fast_copy().
+
+Position::Position() {}
+
+Position::Position(const Position& pos) {
+
+ memcpy(this, &pos, sizeof(Position));
+ detach(); // Always detach() in copy c'tor to avoid surprises
}
-Position::Position(const std::string &fen) {
+Position::Position(const string& fen) {
+
from_fen(fen);
}
+/// Position::detach() copies the content of the current state and castling
+/// masks inside the position itself. This is needed when the st pointee could
+/// become stale, as example because the caller is about to going out of scope.
+
+void Position::detach() {
+
+ startState = *st;
+ st = &startState;
+ st->previous = NULL; // as a safe guard
+}
+
+
/// 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).
-void Position::from_fen(const std::string &fen) {
+void Position::from_fen(const string& fen) {
- static const std::string pieceLetters = "KQRBNPkqrbnp";
+ static const string pieceLetters = "KQRBNPkqrbnp";
static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP };
clear();
continue;
}
size_t idx = pieceLetters.find(fen[i]);
- if (idx == std::string::npos)
+ if (idx == string::npos)
{
std::cout << "Error in FEN at character " << i << std::endl;
return;
}
sideToMove = (fen[i] == 'w' ? WHITE : BLACK);
- // Castling rights:
+ // Castling rights
i++;
if (fen[i] != ' ')
{
}
i++;
- while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) {
- if(fen[i] == '-') {
- i++; break;
- }
- else if(fen[i] == 'K') allow_oo(WHITE);
- else if(fen[i] == 'Q') allow_ooo(WHITE);
- else if(fen[i] == 'k') allow_oo(BLACK);
- else if(fen[i] == 'q') allow_ooo(BLACK);
- else if(fen[i] >= 'A' && fen[i] <= 'H') {
- File rookFile, kingFile = FILE_NONE;
- for(Square square = SQ_B1; square <= SQ_G1; square++)
- if(piece_on(square) == WK)
- kingFile = square_file(square);
- if(kingFile == FILE_NONE) {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
- initialKFile = kingFile;
- rookFile = File(fen[i] - 'A') + FILE_A;
- if(rookFile < initialKFile) {
- allow_ooo(WHITE);
- initialQRFile = rookFile;
- }
- else {
- allow_oo(WHITE);
- initialKRFile = rookFile;
+ while (strchr("KQkqabcdefghABCDEFGH-", fen[i])) {
+ if (fen[i] == '-')
+ {
+ i++;
+ break;
}
- }
- else if(fen[i] >= 'a' && fen[i] <= 'h') {
- File rookFile, kingFile = FILE_NONE;
- for(Square square = SQ_B8; square <= SQ_G8; square++)
- if(piece_on(square) == BK)
- kingFile = square_file(square);
- if(kingFile == FILE_NONE) {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
+ else if (fen[i] == 'K') allow_oo(WHITE);
+ else if (fen[i] == 'Q') allow_ooo(WHITE);
+ else if (fen[i] == 'k') allow_oo(BLACK);
+ else if (fen[i] == 'q') allow_ooo(BLACK);
+ else if (fen[i] >= 'A' && fen[i] <= 'H') {
+ File rookFile, kingFile = FILE_NONE;
+ for (Square square = SQ_B1; square <= SQ_G1; square++)
+ if (piece_on(square) == WK)
+ kingFile = square_file(square);
+ if (kingFile == FILE_NONE) {
+ std::cout << "Error in FEN at character " << i << std::endl;
+ return;
+ }
+ initialKFile = kingFile;
+ rookFile = File(fen[i] - 'A') + FILE_A;
+ if (rookFile < initialKFile) {
+ allow_ooo(WHITE);
+ initialQRFile = rookFile;
+ }
+ else {
+ allow_oo(WHITE);
+ initialKRFile = rookFile;
+ }
}
- initialKFile = kingFile;
- rookFile = File(fen[i] - 'a') + FILE_A;
- if(rookFile < initialKFile) {
- allow_ooo(BLACK);
- initialQRFile = rookFile;
+ else if (fen[i] >= 'a' && fen[i] <= 'h') {
+ File rookFile, kingFile = FILE_NONE;
+ for (Square square = SQ_B8; square <= SQ_G8; square++)
+ if (piece_on(square) == BK)
+ kingFile = square_file(square);
+ if (kingFile == FILE_NONE) {
+ std::cout << "Error in FEN at character " << i << std::endl;
+ return;
+ }
+ initialKFile = kingFile;
+ rookFile = File(fen[i] - 'a') + FILE_A;
+ if (rookFile < initialKFile) {
+ allow_ooo(BLACK);
+ initialQRFile = rookFile;
+ }
+ else {
+ allow_oo(BLACK);
+ initialKRFile = rookFile;
+ }
}
else {
- allow_oo(BLACK);
- initialKRFile = rookFile;
+ std::cout << "Error in FEN at character " << i << std::endl;
+ return;
}
- }
- else {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
- i++;
+ i++;
}
// Skip blanks
while (fen[i] == ' ')
i++;
- // En passant square
- if ( i < fen.length() - 2
+ // En passant square -- ignore if no capture is possible
+ if ( i <= fen.length() - 2
&& (fen[i] >= 'a' && fen[i] <= 'h')
&& (fen[i+1] == '3' || fen[i+1] == '6'))
- epSquare = square_from_string(fen.substr(i, 2));
+ {
+ Square fenEpSquare = square_from_string(fen.substr(i, 2));
+ Color them = opposite_color(sideToMove);
+ if (attacks_from<PAWN>(fenEpSquare, them) & this->pieces(PAWN, sideToMove))
+ st->epSquare = square_from_string(fen.substr(i, 2));
+ }
// Various initialisation
for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
find_checkers();
- key = compute_key();
- pawnKey = compute_pawn_key();
- materialKey = compute_material_key();
- mgValue = compute_mg_value();
- egValue = compute_eg_value();
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->key = compute_key();
+ st->pawnKey = compute_pawn_key();
+ st->materialKey = compute_material_key();
+ st->value = compute_value();
+ st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
+ st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
}
/// Position::to_fen() converts the position object to a FEN string. This is
/// probably only useful for debugging.
-const std::string Position::to_fen() const {
+const string Position::to_fen() const {
- static const std::string pieceLetters = " PNBRQK pnbrqk";
- std::string fen;
+ static const string pieceLetters = " PNBRQK pnbrqk";
+ string fen;
int skip;
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
fen += (char)skip + '0';
skip = 0;
}
- fen += pieceLetters[piece_on(sq)];
+ fen += pieceLetters[piece_on(sq)];
}
if (skip > 0)
fen += (char)skip + '0';
fen += (rank > RANK_1 ? '/' : ' ');
}
- fen += (sideToMove == WHITE ? 'w' : 'b') + ' ';
- if (castleRights != NO_CASTLES)
+ fen += (sideToMove == WHITE ? "w " : "b ");
+ if (st->castleRights != NO_CASTLES)
{
- if (can_castle_kingside(WHITE)) fen += 'K';
- if (can_castle_queenside(WHITE)) fen += 'Q';
- if (can_castle_kingside(BLACK)) fen += 'k';
- if (can_castle_queenside(BLACK)) fen += 'q';
+ if (initialKFile == FILE_E && initialQRFile == FILE_A && initialKRFile == FILE_H)
+ {
+ if (can_castle_kingside(WHITE)) fen += 'K';
+ if (can_castle_queenside(WHITE)) fen += 'Q';
+ if (can_castle_kingside(BLACK)) fen += 'k';
+ if (can_castle_queenside(BLACK)) fen += 'q';
+ }
+ else
+ {
+ if (can_castle_kingside(WHITE))
+ fen += char(toupper(file_to_char(initialKRFile)));
+ if (can_castle_queenside(WHITE))
+ fen += char(toupper(file_to_char(initialQRFile)));
+ if (can_castle_kingside(BLACK))
+ fen += file_to_char(initialKRFile);
+ if (can_castle_queenside(BLACK))
+ fen += file_to_char(initialQRFile);
+ }
} else
fen += '-';
/// Position::print() prints an ASCII representation of the position to
-/// the standard output.
-
-void Position::print() const {
- char pieceStrings[][8] =
- {"| ? ", "| P ", "| N ", "| B ", "| R ", "| Q ", "| K ", "| ? ",
- "| ? ", "|=P=", "|=N=", "|=B=", "|=R=", "|=Q=", "|=K="
- };
-
- for(Rank rank = RANK_8; rank >= RANK_1; rank--) {
- std::cout << "+---+---+---+---+---+---+---+---+\n";
- for(File file = FILE_A; file <= FILE_H; file++) {
- Square sq = make_square(file, rank);
- Piece piece = piece_on(sq);
- if(piece == EMPTY)
- std::cout << ((square_color(sq) == WHITE)? "| " : "| . ");
- else
- std::cout << pieceStrings[piece];
- }
- std::cout << "|\n";
+/// the standard output. If a move is given then also the san is print.
+
+void Position::print(Move m) const {
+
+ static const string pieceLetters = " PNBRQK PNBRQK .";
+
+ // Check for reentrancy, as example when called from inside
+ // MovePicker that is used also here in move_to_san()
+ if (RequestPending)
+ return;
+
+ RequestPending = true;
+
+ std::cout << std::endl;
+ if (m != MOVE_NONE)
+ {
+ Position p(*this);
+ string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
+ std::cout << "Move is: " << col << move_to_san(p, m) << std::endl;
+ }
+ for (Rank rank = RANK_8; rank >= RANK_1; rank--)
+ {
+ std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
+ for (File file = FILE_A; file <= FILE_H; file++)
+ {
+ Square sq = make_square(file, rank);
+ Piece piece = piece_on(sq);
+ if (piece == EMPTY && square_color(sq) == WHITE)
+ piece = NO_PIECE;
+
+ char col = (color_of_piece_on(sq) == BLACK ? '=' : ' ');
+ std::cout << '|' << col << pieceLetters[piece] << col;
+ }
+ std::cout << '|' << std::endl;
}
- std::cout << "+---+---+---+---+---+---+---+---+\n";
- std::cout << to_fen() << std::endl;
- std::cout << key << std::endl;
+ std::cout << "+---+---+---+---+---+---+---+---+" << std::endl
+ << "Fen is: " << to_fen() << std::endl
+ << "Key is: " << st->key << std::endl;
+
+ RequestPending = false;
}
-/// Position::copy() creates a copy of the input position.
+/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the
+/// king) pieces for the given color and for the given pinner type. Or, when
+/// template parameter FindPinned is false, the pieces of the given color
+/// candidate for a discovery check against the enemy king.
+/// Bitboard checkersBB must be already updated when looking for pinners.
-void Position::copy(const Position &pos) {
- memcpy(this, &pos, sizeof(Position));
+template<bool FindPinned>
+Bitboard Position::hidden_checkers(Color c) const {
+
+ Bitboard result = EmptyBoardBB;
+ Bitboard pinners = pieces_of_color(FindPinned ? opposite_color(c) : c);
+
+ // Pinned pieces protect our king, dicovery checks attack
+ // the enemy king.
+ Square ksq = king_square(FindPinned ? c : opposite_color(c));
+
+ // Pinners are sliders, not checkers, that give check when candidate pinned is removed
+ pinners &= (pieces(ROOK, QUEEN) & RookPseudoAttacks[ksq]) | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]);
+
+ if (FindPinned && pinners)
+ pinners &= ~st->checkersBB;
+
+ while (pinners)
+ {
+ Square s = pop_1st_bit(&pinners);
+ Bitboard b = squares_between(s, ksq) & occupied_squares();
+
+ assert(b);
+
+ if ( !(b & (b - 1)) // Only one bit set?
+ && (b & pieces_of_color(c))) // Is an our piece?
+ result |= b;
+ }
+ return result;
}
/// Position:pinned_pieces() returns a bitboard of all pinned (against the
-/// king) pieces for the given color.
+/// king) pieces for the given color. Note that checkersBB bitboard must
+/// be already updated.
Bitboard Position::pinned_pieces(Color c) const {
- Bitboard b1, b2, pinned, pinners, sliders;
- Square ksq = king_square(c), s;
- Color them = opposite_color(c);
-
- pinned = EmptyBoardBB;
- b1 = occupied_squares();
-
- sliders = rooks_and_queens(them) & ~checkers();
- if(sliders & RookPseudoAttacks[ksq]) {
- b2 = piece_attacks<ROOK>(ksq) & pieces_of_color(c);
- pinners = rook_attacks_bb(ksq, b1 ^ b2) & sliders;
- while(pinners) {
- s = pop_1st_bit(&pinners);
- pinned |= (squares_between(s, ksq) & b2);
- }
- }
-
- sliders = bishops_and_queens(them) & ~checkers();
- if(sliders & BishopPseudoAttacks[ksq]) {
- b2 = piece_attacks<BISHOP>(ksq) & pieces_of_color(c);
- pinners = bishop_attacks_bb(ksq, b1 ^ b2) & sliders;
- while(pinners) {
- s = pop_1st_bit(&pinners);
- pinned |= (squares_between(s, ksq) & b2);
- }
- }
- return pinned;
+ return hidden_checkers<true>(c);
}
+
/// Position:discovered_check_candidates() returns a bitboard containing all
/// pieces for the given side which are candidates for giving a discovered
-/// check. The code is almost the same as the function for finding pinned
-/// pieces.
+/// check. Contrary to pinned_pieces() here there is no need of checkersBB
+/// to be already updated.
Bitboard Position::discovered_check_candidates(Color c) const {
- Bitboard b1, b2, dc, checkers, sliders;
- Square ksq = king_square(opposite_color(c)), s;
-
- dc = EmptyBoardBB;
- b1 = occupied_squares();
-
- sliders = rooks_and_queens(c);
- if(sliders & RookPseudoAttacks[ksq]) {
- b2 = piece_attacks<ROOK>(ksq) & pieces_of_color(c);
- checkers = rook_attacks_bb(ksq, b1 ^ b2) & sliders;
- while(checkers) {
- s = pop_1st_bit(&checkers);
- dc |= (squares_between(s, ksq) & b2);
- }
- }
- sliders = bishops_and_queens(c);
- if(sliders & BishopPseudoAttacks[ksq]) {
- b2 = piece_attacks<BISHOP>(ksq) & pieces_of_color(c);
- checkers = bishop_attacks_bb(ksq, b1 ^ b2) & sliders;
- while(checkers) {
- s = pop_1st_bit(&checkers);
- dc |= (squares_between(s, ksq) & b2);
- }
- }
-
- return dc;
+ return hidden_checkers<false>(c);
}
+/// Position::attackers_to() computes a bitboard containing all pieces which
+/// attacks a given square.
-/// Position::square_is_attacked() checks whether the given side attacks the
-/// given square.
+Bitboard Position::attackers_to(Square s) const {
-bool Position::square_is_attacked(Square s, Color c) const {
- return
- (pawn_attacks(opposite_color(c), s) & pawns(c)) ||
- (piece_attacks<KNIGHT>(s) & knights(c)) ||
- (piece_attacks<KING>(s) & kings(c)) ||
- (piece_attacks<ROOK>(s) & rooks_and_queens(c)) ||
- (piece_attacks<BISHOP>(s) & bishops_and_queens(c));
+ return (attacks_from<PAWN>(s, BLACK) & pieces(PAWN, WHITE))
+ | (attacks_from<PAWN>(s, WHITE) & pieces(PAWN, BLACK))
+ | (attacks_from<KNIGHT>(s) & pieces(KNIGHT))
+ | (attacks_from<ROOK>(s) & pieces(ROOK, QUEEN))
+ | (attacks_from<BISHOP>(s) & pieces(BISHOP, QUEEN))
+ | (attacks_from<KING>(s) & pieces(KING));
}
+/// Position::attacks_from() computes a bitboard of all attacks
+/// of a given piece put in a given square.
-/// Position::attacks_to() computes a bitboard containing all pieces which
-/// attacks a given square. There are two versions of this function: One
-/// which finds attackers of both colors, and one which only finds the
-/// attackers for one side.
+Bitboard Position::attacks_from(Piece p, Square s) const {
-Bitboard Position::attacks_to(Square s) const {
- return
- (pawn_attacks(BLACK, s) & pawns(WHITE)) |
- (pawn_attacks(WHITE, s) & pawns(BLACK)) |
- (piece_attacks<KNIGHT>(s) & pieces_of_type(KNIGHT)) |
- (piece_attacks<ROOK>(s) & rooks_and_queens()) |
- (piece_attacks<BISHOP>(s) & bishops_and_queens()) |
- (piece_attacks<KING>(s) & pieces_of_type(KING));
-}
+ assert(square_is_ok(s));
-Bitboard Position::attacks_to(Square s, Color c) const {
- return attacks_to(s) & pieces_of_color(c);
+ switch (p)
+ {
+ case WP: return attacks_from<PAWN>(s, WHITE);
+ case BP: return attacks_from<PAWN>(s, BLACK);
+ case WN: case BN: return attacks_from<KNIGHT>(s);
+ case WB: case BB: return attacks_from<BISHOP>(s);
+ case WR: case BR: return attacks_from<ROOK>(s);
+ case WQ: case BQ: return attacks_from<QUEEN>(s);
+ case WK: case BK: return attacks_from<KING>(s);
+ default: break;
+ }
+ return false;
}
-/// Position::piece_attacks_square() tests whether the piece on square f
-/// attacks square t.
+/// Position::move_attacks_square() tests whether a move from the current
+/// position attacks a given square.
-bool Position::piece_attacks_square(Square f, Square t) const {
- assert(square_is_ok(f));
- assert(square_is_ok(t));
+bool Position::move_attacks_square(Move m, Square s) const {
- switch(piece_on(f)) {
- case WP: return white_pawn_attacks_square(f, t);
- case BP: return black_pawn_attacks_square(f, t);
- case WN: case BN: return knight_attacks_square(f, t);
- case WB: case BB: return bishop_attacks_square(f, t);
- case WR: case BR: return rook_attacks_square(f, t);
- case WQ: case BQ: return queen_attacks_square(f, t);
- case WK: case BK: return king_attacks_square(f, t);
- default: return false;
- }
+ assert(move_is_ok(m));
+ assert(square_is_ok(s));
- return false;
+ Square f = move_from(m), t = move_to(m);
+
+ assert(square_is_occupied(f));
+
+ if (bit_is_set(attacks_from(piece_on(f), t), s))
+ return true;
+
+ // Move the piece and scan for X-ray attacks behind it
+ Bitboard occ = occupied_squares();
+ Color us = color_of_piece_on(f);
+ clear_bit(&occ, f);
+ set_bit(&occ, t);
+ Bitboard xray = ( (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN))
+ |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN))) & pieces_of_color(us);
+
+ // If we have attacks we need to verify that are caused by our move
+ // and are not already existent ones.
+ return xray && (xray ^ (xray & attacks_from<QUEEN>(s)));
}
/// Position::find_checkers() computes the checkersBB bitboard, which
-/// contains a nonzero bit for each checking piece (0, 1 or 2). It
-/// currently works by calling Position::attacks_to, which is probably
-/// inefficient. Consider rewriting this function to use the last move
+/// contains a nonzero bit for each checking piece (0, 1 or 2). It
+/// currently works by calling Position::attackers_to, which is probably
+/// inefficient. Consider rewriting this function to use the last move
/// played, like in non-bitboard versions of Glaurung.
void Position::find_checkers() {
- checkersBB = attacks_to(king_square(side_to_move()),
- opposite_color(side_to_move()));
-}
-
-/// Position::move_is_legal() tests whether a pseudo-legal move is legal.
-/// There are two versions of this function: One which takes only a
-/// move as input, and one which takes a move and a bitboard of pinned
-/// pieces. The latter function is faster, and should always be preferred
-/// when a pinned piece bitboard has already been computed.
-
-bool Position::move_is_legal(Move m) const {
- return move_is_legal(m, pinned_pieces(side_to_move()));
+ Color us = side_to_move();
+ st->checkersBB = attackers_to(king_square(us)) & pieces_of_color(opposite_color(us));
}
-bool Position::move_is_legal(Move m, Bitboard pinned) const {
- Color us, them;
- Square ksq, from;
+/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
+
+bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
assert(is_ok());
assert(move_is_ok(m));
assert(pinned == pinned_pieces(side_to_move()));
- // If we're in check, all pseudo-legal moves are legal, because our
- // check evasion generator only generates true legal moves.
- if(is_check()) return true;
-
// Castling moves are checked for legality during move generation.
- if(move_is_castle(m)) return true;
-
- us = side_to_move();
- them = opposite_color(us);
+ if (move_is_castle(m))
+ return true;
- from = move_from(m);
- ksq = king_square(us);
+ Color us = side_to_move();
+ Square from = move_from(m);
assert(color_of_piece_on(from) == us);
- assert(piece_on(ksq) == king_of_color(us));
+ assert(piece_on(king_square(us)) == piece_of_color_and_type(us, KING));
- // En passant captures are a tricky special case. Because they are
+ // En passant captures are a tricky special case. Because they are
// rather uncommon, we do it simply by testing whether the king is attacked
- // after the move is made:
- if(move_is_ep(m)) {
- Square to = move_to(m);
- Square capsq = make_square(square_file(to), square_rank(from));
- Bitboard b = occupied_squares();
-
- assert(to == ep_square());
- assert(piece_on(from) == pawn_of_color(us));
- assert(piece_on(capsq) == pawn_of_color(them));
- assert(piece_on(to) == EMPTY);
-
- clear_bit(&b, from); clear_bit(&b, capsq); set_bit(&b, to);
- return
- (!(rook_attacks_bb(ksq, b) & rooks_and_queens(them)) &&
- !(bishop_attacks_bb(ksq, b) & bishops_and_queens(them)));
+ // after the move is made
+ if (move_is_ep(m))
+ {
+ Color them = opposite_color(us);
+ Square to = move_to(m);
+ Square capsq = make_square(square_file(to), square_rank(from));
+ Bitboard b = occupied_squares();
+ Square ksq = king_square(us);
+
+ assert(to == ep_square());
+ assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
+ assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
+ assert(piece_on(to) == EMPTY);
+
+ clear_bit(&b, from);
+ clear_bit(&b, capsq);
+ set_bit(&b, to);
+
+ return !(rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them))
+ && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them));
}
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent.
- if(from == ksq) return !(square_is_attacked(move_to(m), them));
+ if (type_of_piece_on(from) == KING)
+ return !(attackers_to(move_to(m)) & pieces_of_color(opposite_color(us)));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
- if(!bit_is_set(pinned, from)) return true;
- if(direction_between_squares(from, ksq) ==
- direction_between_squares(move_to(m), ksq))
- return true;
+ return ( !pinned
+ || !bit_is_set(pinned, from)
+ || (direction_between_squares(from, king_square(us)) == direction_between_squares(move_to(m), king_square(us))));
+}
- return false;
+
+/// Position::pl_move_is_evasion() tests whether a pseudo-legal move is a legal evasion
+
+bool Position::pl_move_is_evasion(Move m, Bitboard pinned) const
+{
+ assert(is_check());
+
+ Color us = side_to_move();
+ Square from = move_from(m);
+ Square to = move_to(m);
+
+ // King moves and en-passant captures are verified in pl_move_is_legal()
+ if (type_of_piece_on(from) == KING || move_is_ep(m))
+ return pl_move_is_legal(m, pinned);
+
+ Bitboard target = checkers();
+ Square checksq = pop_1st_bit(&target);
+
+ if (target) // double check ?
+ return false;
+
+ // Our move must be a blocking evasion or a capture of the checking piece
+ target = squares_between(checksq, king_square(us)) | checkers();
+ return bit_is_set(target, to) && pl_move_is_legal(m, pinned);
}
-/// Position::move_is_check() tests whether a pseudo-legal move is a check.
-/// There are two versions of this function: One which takes only a move as
-/// input, and one which takes a move and a bitboard of discovered check
-/// candidates. The latter function is faster, and should always be preferred
-/// when a discovered check candidates bitboard has already been computed.
+/// Position::move_is_check() tests whether a pseudo-legal move is a check
bool Position::move_is_check(Move m) const {
- Bitboard dc = discovered_check_candidates(side_to_move());
- return move_is_check(m, dc);
-}
+ return move_is_check(m, CheckInfo(*this));
+}
-bool Position::move_is_check(Move m, Bitboard dcCandidates) const {
- Color us, them;
- Square ksq, from, to;
+bool Position::move_is_check(Move m, const CheckInfo& ci) const {
assert(is_ok());
assert(move_is_ok(m));
- assert(dcCandidates ==
- discovered_check_candidates(side_to_move()));
+ assert(ci.dcCandidates == discovered_check_candidates(side_to_move()));
+ assert(color_of_piece_on(move_from(m)) == side_to_move());
+ assert(piece_on(ci.ksq) == piece_of_color_and_type(opposite_color(side_to_move()), KING));
- us = side_to_move();
- them = opposite_color(us);
-
- from = move_from(m);
- to = move_to(m);
- ksq = king_square(them);
- assert(color_of_piece_on(from) == us);
- assert(piece_on(ksq) == king_of_color(them));
+ Square from = move_from(m);
+ Square to = move_to(m);
+ PieceType pt = type_of_piece_on(from);
- // Proceed according to the type of the moving piece:
- switch(type_of_piece_on(from)) {
- case PAWN:
- // Normal check?
- if(bit_is_set(pawn_attacks(them, ksq), to))
+ // Direct check ?
+ if (bit_is_set(ci.checkSq[pt], to))
return true;
- // Discovered check?
- else if(bit_is_set(dcCandidates, from) &&
- direction_between_squares(from, ksq) !=
- direction_between_squares(to, ksq))
- return true;
- // Promotion with check?
- else if(move_promotion(m)) {
- Bitboard b = occupied_squares();
+
+ // Discovery check ?
+ if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
+ {
+ // For pawn and king moves we need to verify also direction
+ if ( (pt != PAWN && pt != KING)
+ ||(direction_between_squares(from, ci.ksq) != direction_between_squares(to, ci.ksq)))
+ return true;
+ }
+
+ // Can we skip the ugly special cases ?
+ if (!move_is_special(m))
+ return false;
+
+ Color us = side_to_move();
+ Bitboard b = occupied_squares();
+
+ // Promotion with check ?
+ if (move_is_promotion(m))
+ {
clear_bit(&b, from);
- switch(move_promotion(m)) {
+ switch (move_promotion_piece(m))
+ {
case KNIGHT:
- return knight_attacks_square(to, ksq);
+ return bit_is_set(attacks_from<KNIGHT>(to), ci.ksq);
case BISHOP:
- return bit_is_set(bishop_attacks_bb(to, b), ksq);
+ return bit_is_set(bishop_attacks_bb(to, b), ci.ksq);
case ROOK:
- return bit_is_set(rook_attacks_bb(to, b), ksq);
+ return bit_is_set(rook_attacks_bb(to, b), ci.ksq);
case QUEEN:
- return bit_is_set(queen_attacks_bb(to, b), ksq);
+ return bit_is_set(queen_attacks_bb(to, b), ci.ksq);
default:
- assert(false);
+ assert(false);
}
- }
- // 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.
- else if(move_is_ep(m)) {
- Square capsq = make_square(square_file(to), square_rank(from));
- Bitboard b = occupied_squares();
-
- clear_bit(&b, from); clear_bit(&b, capsq); set_bit(&b, to);
- return
- ((rook_attacks_bb(ksq, b) & rooks_and_queens(us)) ||
- (bishop_attacks_bb(ksq, b) & bishops_and_queens(us)));
- }
- return false;
-
- case KNIGHT:
- // Discovered check?
- if(bit_is_set(dcCandidates, from))
- return true;
- // Normal check?
- else
- return bit_is_set(piece_attacks<KNIGHT>(ksq), to);
+ }
- case BISHOP:
- // Discovered check?
- if(bit_is_set(dcCandidates, from))
- return true;
- // Normal check?
- else
- return bit_is_set(piece_attacks<BISHOP>(ksq), to);
+ // 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 (move_is_ep(m))
+ {
+ Square capsq = make_square(square_file(to), square_rank(from));
+ clear_bit(&b, from);
+ clear_bit(&b, capsq);
+ set_bit(&b, to);
+ return (rook_attacks_bb(ci.ksq, b) & pieces(ROOK, QUEEN, us))
+ ||(bishop_attacks_bb(ci.ksq, b) & pieces(BISHOP, QUEEN, us));
+ }
- case ROOK:
- // Discovered check?
- if(bit_is_set(dcCandidates, from))
- return true;
- // Normal check?
- else
- return bit_is_set(piece_attacks<ROOK>(ksq), to);
-
- case QUEEN:
- // Discovered checks are impossible!
- assert(!bit_is_set(dcCandidates, from));
- // Normal check?
- return bit_is_set(piece_attacks<QUEEN>(ksq), to);
-
- case KING:
- // Discovered check?
- if(bit_is_set(dcCandidates, from) &&
- direction_between_squares(from, ksq) !=
- direction_between_squares(to, ksq))
- return true;
- // Castling with check?
- if(move_is_castle(m)) {
+ // Castling with check ?
+ if (move_is_castle(m))
+ {
Square kfrom, kto, rfrom, rto;
- Bitboard b = occupied_squares();
-
kfrom = from;
rfrom = to;
- if(rfrom > kfrom) {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- }
- else {
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
-
- clear_bit(&b, kfrom); clear_bit(&b, rfrom);
- set_bit(&b, rto); set_bit(&b, kto);
- return bit_is_set(rook_attacks_bb(rto, b), ksq);
- }
-
- return false;
-
- default:
- assert(false);
- return false;
+ if (rfrom > kfrom)
+ {
+ kto = relative_square(us, SQ_G1);
+ rto = relative_square(us, SQ_F1);
+ } else {
+ kto = relative_square(us, SQ_C1);
+ rto = relative_square(us, SQ_D1);
+ }
+ clear_bit(&b, kfrom);
+ clear_bit(&b, rfrom);
+ set_bit(&b, rto);
+ set_bit(&b, kto);
+ return bit_is_set(rook_attacks_bb(rto, b), ci.ksq);
}
- assert(false);
return false;
}
-/// Position::move_is_capture() tests whether a move from the current
-/// position is a capture.
+/// Position::do_move() makes a move, and saves all information necessary
+/// to a StateInfo object. The move is assumed to be legal.
+/// Pseudo-legal moves should be filtered out before this function is called.
+
+void Position::do_move(Move m, StateInfo& newSt) {
-bool Position::move_is_capture(Move m) const {
- return
- color_of_piece_on(move_to(m)) == opposite_color(side_to_move())
- || move_is_ep(m);
+ CheckInfo ci(*this);
+ do_move(m, newSt, ci, move_is_check(m, ci));
}
+void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) {
-/// Position::move_attacks_square() tests whether a move from the current
-/// position attacks a given square. Only attacks by the moving piece are
-/// considered; the function does not handle X-ray attacks.
-
-bool Position::move_attacks_square(Move m, Square s) const {
+ assert(is_ok());
assert(move_is_ok(m));
- assert(square_is_ok(s));
- Square f = move_from(m), t = move_to(m);
+ Key key = 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.
+ struct ReducedStateInfo {
+ Key pawnKey, materialKey;
+ int castleRights, rule50, pliesFromNull;
+ Square epSquare;
+ Score value;
+ Value npMaterial[2];
+ };
- assert(square_is_occupied(f));
+ memcpy(&newSt, st, sizeof(ReducedStateInfo));
+ newSt.previous = st;
+ st = &newSt;
+
+ // Save the current key to the history[] array, in order to be able to
+ // detect repetition draws.
+ history[gamePly] = key;
+ gamePly++;
+
+ // Update side to move
+ key ^= zobSideToMove;
+
+ // Increment the 50 moves rule draw counter. Resetting it to zero in the
+ // case of non-reversible moves is taken care of later.
+ st->rule50++;
+ st->pliesFromNull++;
- switch(piece_on(f)) {
- case WP: return white_pawn_attacks_square(t, s);
- case BP: return black_pawn_attacks_square(t, s);
- case WN: case BN: return knight_attacks_square(t, s);
- case WB: case BB: return bishop_attacks_square(t, s);
- case WR: case BR: return rook_attacks_square(t, s);
- case WQ: case BQ: return queen_attacks_square(t, s);
- case WK: case BK: return king_attacks_square(t, s);
- default: assert(false);
+ if (move_is_castle(m))
+ {
+ st->key = key;
+ do_castle_move(m);
+ return;
}
- return false;
-}
+ Color us = side_to_move();
+ Color them = opposite_color(us);
+ Square from = move_from(m);
+ Square to = move_to(m);
+ bool ep = move_is_ep(m);
+ bool pm = move_is_promotion(m);
+ Piece piece = piece_on(from);
+ PieceType pt = type_of_piece(piece);
+ PieceType capture = ep ? 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(!(ep || pm) || piece == piece_of_color_and_type(us, PAWN));
+ assert(!pm || relative_rank(us, to) == RANK_8);
-/// Position::backup() is called when making a move. All information
-/// necessary to restore the position when the move is later unmade
-/// is saved to an UndoInfo object. The function Position::restore
-/// does the reverse operation: When one does a backup followed by
-/// a restore with the same UndoInfo object, the position is restored
-/// to the state before backup was called.
-
-void Position::backup(UndoInfo &u) const {
- u.castleRights = castleRights;
- u.epSquare = epSquare;
- u.checkersBB = checkersBB;
- u.key = key;
- u.pawnKey = pawnKey;
- u.materialKey = materialKey;
- u.rule50 = rule50;
- u.lastMove = lastMove;
- u.capture = NO_PIECE_TYPE;
- u.mgValue = mgValue;
- u.egValue = egValue;
-}
+ if (capture)
+ do_capture_move(key, capture, them, to, ep);
+ // Update hash key
+ key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
-/// Position::restore() is called when unmaking a move. It copies back
-/// the information backed up during a previous call to Position::backup.
-
-void Position::restore(const UndoInfo &u) {
- castleRights = u.castleRights;
- epSquare = u.epSquare;
- checkersBB = u.checkersBB;
- key = u.key;
- pawnKey = u.pawnKey;
- materialKey = u.materialKey;
- rule50 = u.rule50;
- lastMove = u.lastMove;
- mgValue = u.mgValue;
- egValue = u.egValue;
-}
+ // Reset en passant square
+ if (st->epSquare != SQ_NONE)
+ {
+ key ^= zobEp[st->epSquare];
+ st->epSquare = SQ_NONE;
+ }
+ // Update castle rights, try to shortcut a common case
+ int cm = castleRightsMask[from] & castleRightsMask[to];
+ if (cm != ALL_CASTLES && ((cm & st->castleRights) != st->castleRights))
+ {
+ key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[from];
+ st->castleRights &= castleRightsMask[to];
+ key ^= zobCastle[st->castleRights];
+ }
-/// Position::do_move() makes a move, and backs up all information necessary
-/// to undo the move to an UndoInfo object. The move is assumed to be legal.
-/// Pseudo-legal moves should be filtered out before this function is called.
-/// There are two versions of this function, one which takes only the move and
-/// the UndoInfo as input, and one which takes a third parameter, a bitboard of
-/// discovered check candidates. The second version is faster, because knowing
-/// the discovered check candidates makes it easier to update the checkersBB
-/// member variable in the position object.
-
-void Position::do_move(Move m, UndoInfo &u) {
- do_move(m, u, discovered_check_candidates(side_to_move()));
-}
+ // Prefetch TT access as soon as we know key is updated
+ TT.prefetch(key);
-void Position::do_move(Move m, UndoInfo &u, Bitboard dcCandidates) {
- assert(is_ok());
- assert(move_is_ok(m));
+ // Move the piece
+ Bitboard move_bb = make_move_bb(from, to);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[pt]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
- // Back up the necessary information to our UndoInfo object (except the
- // captured piece, which is taken care of later:
- backup(u);
+ board[to] = board[from];
+ board[from] = EMPTY;
- // Save the current key to the history[] array, in order to be able to
- // detect repetition draws:
- history[gamePly] = key;
+ // 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.
+ index[to] = index[from];
+ pieceList[us][pt][index[to]] = to;
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of non-reversible moves is taken care of later.
- rule50++;
+ // If the moving piece was a pawn do some special extra work
+ if (pt == PAWN)
+ {
+ // Reset rule 50 draw counter
+ st->rule50 = 0;
- if(move_is_castle(m))
- do_castle_move(m);
- else if(move_promotion(m))
- do_promotion_move(m, u);
- else if(move_is_ep(m))
- do_ep_move(m);
- else {
- Color us, them;
- Square from, to;
- PieceType piece, capture;
+ // Update pawn hash key
+ st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- us = side_to_move();
- them = opposite_color(us);
+ // Set en passant square, only if moved pawn can be captured
+ if ((to ^ from) == 16)
+ {
+ if (attacks_from<PAWN>(from + (us == WHITE ? DELTA_N : DELTA_S), us) & pieces(PAWN, them))
+ {
+ st->epSquare = Square((int(from) + int(to)) / 2);
+ key ^= zobEp[st->epSquare];
+ }
+ }
+ }
- from = move_from(m);
- to = move_to(m);
+ // Update incremental scores
+ st->value += pst_delta(piece, from, to);
- assert(color_of_piece_on(from) == us);
- assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY);
+ // Set capture piece
+ st->capture = capture;
- piece = type_of_piece_on(from);
- capture = type_of_piece_on(to);
+ if (pm) // promotion ?
+ {
+ PieceType promotion = move_promotion_piece(m);
+
+ assert(promotion >= KNIGHT && promotion <= QUEEN);
+
+ // Insert promoted piece instead of pawn
+ clear_bit(&(byTypeBB[PAWN]), to);
+ set_bit(&(byTypeBB[promotion]), to);
+ board[to] = piece_of_color_and_type(us, promotion);
+
+ // Update piece counts
+ pieceCount[us][promotion]++;
+ pieceCount[us][PAWN]--;
+
+ // Update material key
+ st->materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]];
+ st->materialKey ^= zobMaterial[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;
+ pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE;
+ index[to] = pieceCount[us][promotion] - 1;
+ pieceList[us][promotion][index[to]] = to;
+
+ // Partially revert hash keys update
+ key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to];
+ st->pawnKey ^= zobrist[us][PAWN][to];
+
+ // Partially revert and update incremental scores
+ st->value -= pst(us, PAWN, to);
+ st->value += pst(us, promotion, to);
+
+ // Update material
+ st->npMaterial[us] += piece_value_midgame(promotion);
+ }
- if(capture) {
- assert(capture != KING);
+ // Update the key with the final value
+ st->key = key;
- // Remove captured piece:
- clear_bit(&(byColorBB[them]), to);
- clear_bit(&(byTypeBB[capture]), to);
+ // Update checkers bitboard, piece must be already moved
+ st->checkersBB = EmptyBoardBB;
- // Update hash key:
- key ^= zobrist[them][capture][to];
+ if (moveIsCheck)
+ {
+ if (ep | pm)
+ st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us);
+ else
+ {
+ // Direct checks
+ if (bit_is_set(ci.checkSq[pt], to))
+ st->checkersBB = SetMaskBB[to];
- // If the captured piece was a pawn, update pawn hash key:
- if(capture == PAWN)
- pawnKey ^= zobrist[them][PAWN][to];
+ // Discovery checks
+ if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
+ {
+ if (pt != ROOK)
+ st->checkersBB |= (attacks_from<ROOK>(ci.ksq) & pieces(ROOK, QUEEN, us));
- // Update incremental scores:
- mgValue -= mg_pst(them, capture, to);
- egValue -= eg_pst(them, capture, to);
+ if (pt != BISHOP)
+ st->checkersBB |= (attacks_from<BISHOP>(ci.ksq) & pieces(BISHOP, QUEEN, us));
+ }
+ }
+ }
- // Update material:
- if(capture != PAWN)
- npMaterial[them] -= piece_value_midgame(capture);
+ // Finish
+ sideToMove = opposite_color(sideToMove);
+ st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
- // Update material hash key:
- materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
+ assert(is_ok());
+}
- // Update piece count:
- pieceCount[them][capture]--;
- // Update piece list:
- pieceList[them][capture][index[to]] =
- pieceList[them][capture][pieceCount[them][capture]];
- index[pieceList[them][capture][index[to]]] = index[to];
+/// Position::do_capture_move() is a private method used to update captured
+/// piece info. It is called from the main Position::do_move function.
- // Remember the captured piece, in order to be able to undo the move
- // correctly:
- u.capture = capture;
+void Position::do_capture_move(Key& key, PieceType capture, Color them, Square to, bool ep) {
- // Reset rule 50 counter:
- rule50 = 0;
- }
+ assert(capture != KING);
- // Move the piece:
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[piece]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[piece]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = board[from];
- board[from] = EMPTY;
-
- // Update hash key:
- key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to];
-
- // Update incremental scores:
- mgValue -= mg_pst(us, piece, from);
- mgValue += mg_pst(us, piece, to);
- egValue -= eg_pst(us, piece, from);
- egValue += eg_pst(us, piece, to);
-
- // If the moving piece was a king, update the king square:
- if(piece == KING)
- kingSquare[us] = to;
-
- // If the move was a double pawn push, set the en passant square.
- // This code is a bit ugly right now, and should be cleaned up later.
- // FIXME
- if(epSquare != SQ_NONE) {
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
- }
- if(piece == PAWN) {
- if(abs(int(to) - int(from)) == 16) {
- if((us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) &
- pawns(BLACK))) ||
- (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) &
- pawns(WHITE)))) {
- epSquare = Square((int(from) + int(to)) / 2);
- key ^= zobEp[epSquare];
- }
- }
- // Reset rule 50 draw counter.
- rule50 = 0;
- // Update pawn hash key:
- pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- }
+ Square capsq = to;
+
+ if (ep) // en passant ?
+ {
+ capsq = (them == BLACK)? (to - DELTA_N) : (to - DELTA_S);
- // Update piece lists:
- pieceList[us][piece][index[from]] = to;
- index[to] = index[from];
-
- // Update castle rights:
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[from];
- castleRights &= castleRightsMask[to];
- key ^= zobCastle[castleRights];
-
- // Update checkers bitboard:
- checkersBB = EmptyBoardBB;
- Square ksq = king_square(them);
-
- switch(piece) {
-
- case PAWN:
- if(bit_is_set(pawn_attacks(them, ksq), to))
- set_bit(&checkersBB, to);
- if(bit_is_set(dcCandidates, from))
- checkersBB |=
- ((piece_attacks<ROOK>(ksq) & rooks_and_queens(us)) |
- (piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- case KNIGHT:
- if(bit_is_set(piece_attacks<KNIGHT>(ksq), to))
- set_bit(&checkersBB, to);
- if(bit_is_set(dcCandidates, from))
- checkersBB |=
- ((piece_attacks<ROOK>(ksq) & rooks_and_queens(us)) |
- (piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- case BISHOP:
- if(bit_is_set(piece_attacks<BISHOP>(ksq), to))
- set_bit(&checkersBB, to);
- if(bit_is_set(dcCandidates, from))
- checkersBB |=
- (piece_attacks<ROOK>(ksq) & rooks_and_queens(us));
- break;
-
- case ROOK:
- if(bit_is_set(piece_attacks<ROOK>(ksq), to))
- set_bit(&checkersBB, to);
- if(bit_is_set(dcCandidates, from))
- checkersBB |=
- (piece_attacks<BISHOP>(ksq) & bishops_and_queens(us));
- break;
-
- case QUEEN:
- if(bit_is_set(piece_attacks<QUEEN>(ksq), to))
- set_bit(&checkersBB, to);
- break;
-
- case KING:
- if(bit_is_set(dcCandidates, from))
- checkersBB |=
- ((piece_attacks<ROOK>(ksq) & rooks_and_queens(us)) |
- (piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- default:
- assert(false);
- break;
+ assert(to == st->epSquare);
+ assert(relative_rank(opposite_color(them), to) == RANK_6);
+ assert(piece_on(to) == EMPTY);
+ assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
+
+ board[capsq] = EMPTY;
}
- }
- // Finish
- key ^= zobSideToMove;
- sideToMove = opposite_color(sideToMove);
- gamePly++;
+ // Remove captured piece
+ clear_bit(&(byColorBB[them]), capsq);
+ clear_bit(&(byTypeBB[capture]), capsq);
+ clear_bit(&(byTypeBB[0]), capsq);
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ // Update hash key
+ key ^= zobrist[them][capture][capsq];
- assert(is_ok());
+ // Update incremental scores
+ st->value -= pst(them, capture, capsq);
+
+ // If the captured piece was a pawn, update pawn hash key,
+ // otherwise update non-pawn material.
+ if (capture == PAWN)
+ st->pawnKey ^= zobrist[them][PAWN][capsq];
+ else
+ st->npMaterial[them] -= piece_value_midgame(capture);
+
+ // Update piece count
+ pieceCount[them][capture]--;
+
+ // Update material hash key
+ st->materialKey ^= zobMaterial[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;
+
+ // Reset rule 50 counter
+ st->rule50 = 0;
}
/// Position::do_castle_move() is a private method used to make a castling
-/// move. It is called from the main Position::do_move function. Note that
+/// move. It is called from the main Position::do_move function. 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.
void Position::do_castle_move(Move m) {
- Color us, them;
- Square kfrom, kto, rfrom, rto;
- assert(is_ok());
assert(move_is_ok(m));
assert(move_is_castle(m));
- us = side_to_move();
- them = opposite_color(us);
+ Color us = side_to_move();
+ Color them = opposite_color(us);
- // Find source squares for king and rook:
- kfrom = move_from(m);
- rfrom = move_to(m); // HACK: See comment at beginning of function.
+ // Reset capture field
+ st->capture = NO_PIECE_TYPE;
- assert(piece_on(kfrom) == king_of_color(us));
- assert(piece_on(rfrom) == rook_of_color(us));
+ // Find source squares for king and rook
+ Square kfrom = move_from(m);
+ Square rfrom = move_to(m); // HACK: See comment at beginning of function
+ Square kto, rto;
- // Find destination squares for king and rook:
- if(rfrom > kfrom) { // O-O
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- }
- else { // O-O-O
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
+ assert(piece_on(kfrom) == piece_of_color_and_type(us, KING));
+ assert(piece_on(rfrom) == piece_of_color_and_type(us, ROOK));
+
+ // Find destination squares for king and rook
+ if (rfrom > kfrom) // O-O
+ {
+ kto = relative_square(us, SQ_G1);
+ rto = relative_square(us, SQ_F1);
+ } else { // O-O-O
+ kto = relative_square(us, SQ_C1);
+ rto = relative_square(us, SQ_D1);
}
// Remove pieces from source squares:
set_bit(&(byTypeBB[ROOK]), rto);
set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares
- // Update board array:
+ // Update board array
+ Piece king = piece_of_color_and_type(us, KING);
+ Piece rook = piece_of_color_and_type(us, ROOK);
board[kfrom] = board[rfrom] = EMPTY;
- board[kto] = king_of_color(us);
- board[rto] = rook_of_color(us);
+ board[kto] = king;
+ board[rto] = rook;
- // Update king square:
- kingSquare[us] = kto;
-
- // Update piece lists:
+ // Update piece lists
pieceList[us][KING][index[kfrom]] = kto;
pieceList[us][ROOK][index[rfrom]] = rto;
- int tmp = index[rfrom];
+ int tmp = index[rfrom]; // In Chess960 could be rto == kfrom
index[kto] = index[kfrom];
index[rto] = tmp;
- // Update incremental scores:
- mgValue -= mg_pst(us, KING, kfrom);
- mgValue += mg_pst(us, KING, kto);
- egValue -= eg_pst(us, KING, kfrom);
- egValue += eg_pst(us, KING, kto);
- mgValue -= mg_pst(us, ROOK, rfrom);
- mgValue += mg_pst(us, ROOK, rto);
- egValue -= eg_pst(us, ROOK, rfrom);
- egValue += eg_pst(us, ROOK, rto);
-
- // Update hash key:
- key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
-
- // Clear en passant square:
- if(epSquare != SQ_NONE) {
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
- }
+ // Update incremental scores
+ st->value += pst_delta(king, kfrom, kto);
+ st->value += pst_delta(rook, rfrom, rto);
- // Update castling rights:
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[kfrom];
- key ^= zobCastle[castleRights];
+ // Update hash key
+ st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
+ st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
- // Reset rule 50 counter:
- rule50 = 0;
+ // Clear en passant square
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= zobEp[st->epSquare];
+ st->epSquare = SQ_NONE;
+ }
- // Update checkers BB:
- checkersBB = attacks_to(king_square(them), us);
-}
+ // Update castling rights
+ st->key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[kfrom];
+ st->key ^= zobCastle[st->castleRights];
+ // Reset rule 50 counter
+ st->rule50 = 0;
-/// Position::do_promotion_move() is a private method used to make a promotion
-/// move. It is called from the main Position::do_move function. The
-/// UndoInfo object, which has been initialized in Position::do_move, is
-/// used to store the captured piece (if any).
+ // Update checkers BB
+ st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us);
-void Position::do_promotion_move(Move m, UndoInfo &u) {
- Color us, them;
- Square from, to;
- PieceType capture, promotion;
+ // Finish
+ sideToMove = opposite_color(sideToMove);
+ st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
assert(is_ok());
- assert(move_is_ok(m));
- assert(move_promotion(m));
-
- us = side_to_move();
- them = opposite_color(us);
-
- from = move_from(m);
- to = move_to(m);
-
- assert(relative_rank(us, to) == RANK_8);
- assert(piece_on(from) == pawn_of_color(us));
- assert(color_of_piece_on(to) == them || square_is_empty(to));
-
- capture = type_of_piece_on(to);
-
- if(capture) {
- assert(capture != KING);
-
- // Remove captured piece:
- clear_bit(&(byColorBB[them]), to);
- clear_bit(&(byTypeBB[capture]), to);
-
- // Update hash key:
- key ^= zobrist[them][capture][to];
-
- // Update incremental scores:
- mgValue -= mg_pst(them, capture, to);
- egValue -= eg_pst(them, capture, to);
-
- // Update material. Because our move is a promotion, we know that the
- // captured piece is not a pawn.
- assert(capture != PAWN);
- npMaterial[them] -= piece_value_midgame(capture);
+}
- // Update material hash key:
- materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
- // Update piece count:
- pieceCount[them][capture]--;
+/// 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.
- // Update piece list:
- pieceList[them][capture][index[to]] =
- pieceList[them][capture][pieceCount[them][capture]];
- index[pieceList[them][capture][index[to]]] = index[to];
+void Position::undo_move(Move m) {
- // Remember the captured piece, in order to be able to undo the move
- // correctly:
- u.capture = capture;
- }
+ assert(is_ok());
+ assert(move_is_ok(m));
- // Remove pawn:
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[PAWN]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- board[from] = EMPTY;
+ gamePly--;
+ sideToMove = opposite_color(sideToMove);
- // Insert promoted piece:
- promotion = move_promotion(m);
- assert(promotion >= KNIGHT && promotion <= QUEEN);
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[promotion]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = piece_of_color_and_type(us, promotion);
-
- // Update hash key:
- key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to];
-
- // Update pawn hash key:
- pawnKey ^= zobrist[us][PAWN][from];
-
- // Update material key:
- materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]];
- materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1];
-
- // Update piece counts:
- pieceCount[us][PAWN]--;
- pieceCount[us][promotion]++;
-
- // Update piece lists:
- pieceList[us][PAWN][index[from]] =
- pieceList[us][PAWN][pieceCount[us][PAWN]];
- index[pieceList[us][PAWN][index[from]]] = index[from];
- pieceList[us][promotion][pieceCount[us][promotion] - 1] = to;
- index[to] = pieceCount[us][promotion] - 1;
-
- // Update incremental scores:
- mgValue -= mg_pst(us, PAWN, from);
- mgValue += mg_pst(us, promotion, to);
- egValue -= eg_pst(us, PAWN, from);
- egValue += eg_pst(us, promotion, to);
-
- // Update material:
- npMaterial[us] += piece_value_midgame(promotion);
-
- // Clear the en passant square:
- if(epSquare != SQ_NONE) {
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
+ if (move_is_castle(m))
+ {
+ undo_castle_move(m);
+ return;
}
- // Update castle rights:
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[to];
- key ^= zobCastle[castleRights];
+ Color us = side_to_move();
+ Color them = opposite_color(us);
+ Square from = move_from(m);
+ Square to = move_to(m);
+ bool ep = move_is_ep(m);
+ bool pm = move_is_promotion(m);
- // Reset rule 50 counter:
- rule50 = 0;
+ PieceType pt = type_of_piece_on(to);
- // Update checkers BB:
- checkersBB = attacks_to(king_square(them), us);
-}
+ 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) == piece_of_color_and_type(us, PAWN));
+ if (pm) // promotion ?
+ {
+ PieceType promotion = move_promotion_piece(m);
+ pt = PAWN;
+
+ assert(promotion >= KNIGHT && promotion <= QUEEN);
+ assert(piece_on(to) == piece_of_color_and_type(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;
+ }
-/// Position::do_ep_move() is a private method used to make an en passant
-/// capture. It is called from the main Position::do_move function. Because
-/// the captured piece is always a pawn, we don't need to pass an UndoInfo
-/// object in which to store the captured piece.
-void Position::do_ep_move(Move m) {
- Color us, them;
- Square from, to, capsq;
+ // 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(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
- assert(is_ok());
- assert(move_is_ok(m));
- assert(move_is_ep(m));
-
- us = side_to_move();
- them = opposite_color(us);
-
- // Find from, to and capture squares:
- from = move_from(m);
- to = move_to(m);
- capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
-
- assert(to == epSquare);
- assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(to) == EMPTY);
- assert(piece_on(from) == pawn_of_color(us));
- assert(piece_on(capsq) == pawn_of_color(them));
-
- // Remove captured piece:
- clear_bit(&(byColorBB[them]), capsq);
- clear_bit(&(byTypeBB[PAWN]), capsq);
- clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares
- board[capsq] = EMPTY;
-
- // Remove moving piece from source square:
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[PAWN]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
-
- // Put moving piece on destination square:
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[PAWN]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = board[from];
- board[from] = EMPTY;
+ board[from] = piece_of_color_and_type(us, pt);
+ board[to] = EMPTY;
- // Update material hash key:
- materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]];
+ // Update piece list
+ index[from] = index[to];
+ pieceList[us][pt][index[from]] = from;
- // Update piece count:
- pieceCount[them][PAWN]--;
+ if (st->capture)
+ {
+ Square capsq = to;
- // Update piece list:
- pieceList[us][PAWN][index[from]] = to;
- index[to] = index[from];
- pieceList[them][PAWN][index[capsq]] =
- pieceList[them][PAWN][pieceCount[them][PAWN]];
- index[pieceList[them][PAWN][index[capsq]]] = index[capsq];
-
- // Update hash key:
- key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- key ^= zobrist[them][PAWN][capsq];
- key ^= zobEp[epSquare];
-
- // Update pawn hash key:
- pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- pawnKey ^= zobrist[them][PAWN][capsq];
-
- // Update incremental scores:
- mgValue -= mg_pst(them, PAWN, capsq);
- mgValue -= mg_pst(us, PAWN, from);
- mgValue += mg_pst(us, PAWN, to);
- egValue -= eg_pst(them, PAWN, capsq);
- egValue -= eg_pst(us, PAWN, from);
- egValue += eg_pst(us, PAWN, to);
-
- // Reset en passant square:
- epSquare = SQ_NONE;
-
- // Reset rule 50 counter:
- rule50 = 0;
-
- // Update checkers BB:
- checkersBB = attacks_to(king_square(them), us);
-}
+ if (ep)
+ capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
+ assert(st->capture != KING);
+ assert(!ep || square_is_empty(capsq));
-/// Position::undo_move() unmakes a move. When it returns, the position should
-/// be restored to exactly the same state as before the move was made. It is
-/// important that Position::undo_move is called with the same move and UndoInfo
-/// object as the earlier call to Position::do_move.
+ // Restore the captured piece
+ set_bit(&(byColorBB[them]), capsq);
+ set_bit(&(byTypeBB[st->capture]), capsq);
+ set_bit(&(byTypeBB[0]), capsq);
-void Position::undo_move(Move m, const UndoInfo &u) {
- assert(is_ok());
- assert(move_is_ok(m));
+ board[capsq] = piece_of_color_and_type(them, st->capture);
- gamePly--;
- sideToMove = opposite_color(sideToMove);
+ // Update piece count
+ pieceCount[them][st->capture]++;
- // Restore information from our UndoInfo object (except the captured piece,
- // which is taken care of later):
- restore(u);
-
- if(move_is_castle(m))
- undo_castle_move(m);
- else if(move_promotion(m))
- undo_promotion_move(m, u);
- else if(move_is_ep(m))
- undo_ep_move(m);
- else {
- Color us, them;
- Square from, to;
- PieceType piece, capture;
-
- us = side_to_move();
- them = opposite_color(us);
-
- from = move_from(m);
- to = move_to(m);
-
- assert(piece_on(from) == EMPTY);
- assert(color_of_piece_on(to) == us);
-
- // Put the piece back at the source square:
- piece = type_of_piece_on(to);
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[piece]), from);
- set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- board[from] = piece_of_color_and_type(us, piece);
-
- // Clear the destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[piece]), to);
- clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
-
- // If the moving piece was a king, update the king square:
- if(piece == KING)
- kingSquare[us] = from;
-
- // Update piece list:
- pieceList[us][piece][index[to]] = from;
- index[from] = index[to];
-
- capture = u.capture;
-
- if(capture) {
- assert(capture != KING);
- // Replace the captured piece:
- set_bit(&(byColorBB[them]), to);
- set_bit(&(byTypeBB[capture]), to);
- set_bit(&(byTypeBB[0]), to);
- board[to] = piece_of_color_and_type(them, capture);
-
- // Update material:
- if(capture != PAWN)
- npMaterial[them] += piece_value_midgame(capture);
-
- // Update piece list:
- pieceList[them][capture][pieceCount[them][capture]] = to;
- index[to] = pieceCount[them][capture];
-
- // Update piece count:
- pieceCount[them][capture]++;
- }
- else
- board[to] = EMPTY;
+ // Update piece list, add a new captured piece in capsq square
+ index[capsq] = pieceCount[them][st->capture] - 1;
+ pieceList[them][st->capture][index[capsq]] = capsq;
}
+ // Finally point our state pointer back to the previous state
+ st = st->previous;
+
assert(is_ok());
}
/// Position::undo_castle_move() is a private method used to unmake a castling
-/// move. It is called from the main Position::undo_move function. Note that
+/// move. It is called from the main Position::undo_move function. 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.
void Position::undo_castle_move(Move m) {
- Color us, them;
- Square kfrom, kto, rfrom, rto;
assert(move_is_ok(m));
assert(move_is_castle(m));
// When we have arrived here, some work has already been done by
// Position::undo_move. In particular, the side to move has been switched,
// so the code below is correct.
- us = side_to_move();
- them = opposite_color(us);
+ Color us = side_to_move();
- // Find source squares for king and rook:
- kfrom = move_from(m);
- rfrom = move_to(m); // HACK: See comment at beginning of function.
+ // Find source squares for king and rook
+ Square kfrom = move_from(m);
+ Square rfrom = move_to(m); // HACK: See comment at beginning of function
+ Square kto, rto;
- // Find destination squares for king and rook:
- if(rfrom > kfrom) { // O-O
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- }
- else { // O-O-O
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
+ // Find destination squares for king and rook
+ if (rfrom > kfrom) // O-O
+ {
+ kto = relative_square(us, SQ_G1);
+ rto = relative_square(us, SQ_F1);
+ } else { // O-O-O
+ kto = relative_square(us, SQ_C1);
+ rto = relative_square(us, SQ_D1);
}
- assert(piece_on(kto) == king_of_color(us));
- assert(piece_on(rto) == rook_of_color(us));
+ assert(piece_on(kto) == piece_of_color_and_type(us, KING));
+ assert(piece_on(rto) == piece_of_color_and_type(us, ROOK));
// Remove pieces from destination squares:
clear_bit(&(byColorBB[us]), kto);
set_bit(&(byTypeBB[ROOK]), rfrom);
set_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares
- // Update board:
+ // Update board
board[rto] = board[kto] = EMPTY;
- board[rfrom] = rook_of_color(us);
- board[kfrom] = king_of_color(us);
-
- // Update king square:
- kingSquare[us] = kfrom;
+ board[rfrom] = piece_of_color_and_type(us, ROOK);
+ board[kfrom] = piece_of_color_and_type(us, KING);
- // Update piece lists:
+ // Update piece lists
pieceList[us][KING][index[kto]] = kfrom;
pieceList[us][ROOK][index[rto]] = rfrom;
- int tmp = index[rto]; // Necessary because we may have rto == kfrom in FRC.
+ int tmp = index[rto]; // In Chess960 could be rto == kfrom
index[kfrom] = index[kto];
index[rfrom] = tmp;
-}
-
-
-/// Position::undo_promotion_move() is a private method used to unmake a
-/// promotion move. It is called from the main Position::do_move
-/// function. The UndoInfo object, which has been initialized in
-/// Position::do_move, is used to put back the captured piece (if any).
-
-void Position::undo_promotion_move(Move m, const UndoInfo &u) {
- Color us, them;
- Square from, to;
- PieceType capture, promotion;
-
- assert(move_is_ok(m));
- assert(move_promotion(m));
-
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- us = side_to_move();
- them = opposite_color(us);
-
- from = move_from(m);
- to = move_to(m);
-
- assert(relative_rank(us, to) == RANK_8);
- assert(piece_on(from) == EMPTY);
-
- // Remove promoted piece:
- promotion = move_promotion(m);
- assert(piece_on(to)==piece_of_color_and_type(us, promotion));
- assert(promotion >= KNIGHT && promotion <= QUEEN);
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[promotion]), to);
- clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
-
- // Insert pawn at source square:
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[PAWN]), from);
- set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- board[from] = pawn_of_color(us);
-
- // Update material:
- npMaterial[us] -= piece_value_midgame(promotion);
-
- // Update piece list:
- pieceList[us][PAWN][pieceCount[us][PAWN]] = from;
- index[from] = pieceCount[us][PAWN];
- pieceList[us][promotion][index[to]] =
- pieceList[us][promotion][pieceCount[us][promotion] - 1];
- index[pieceList[us][promotion][index[to]]] = index[to];
-
- // Update piece counts:
- pieceCount[us][promotion]--;
- pieceCount[us][PAWN]++;
-
- capture = u.capture;
- if(capture) {
- assert(capture != KING);
-
- // Insert captured piece:
- set_bit(&(byColorBB[them]), to);
- set_bit(&(byTypeBB[capture]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = piece_of_color_and_type(them, capture);
-
- // Update material. Because the move is a promotion move, we know
- // that the captured piece cannot be a pawn.
- assert(capture != PAWN);
- npMaterial[them] += piece_value_midgame(capture);
-
- // Update piece list:
- pieceList[them][capture][pieceCount[them][capture]] = to;
- index[to] = pieceCount[them][capture];
-
- // Update piece count:
- pieceCount[them][capture]++;
- }
- else
- board[to] = EMPTY;
-}
+ // Finally point our state pointer back to the previous state
+ st = st->previous;
-/// Position::undo_ep_move() is a private method used to unmake an en passant
-/// capture. It is called from the main Position::undo_move function. Because
-/// the captured piece is always a pawn, we don't need to pass an UndoInfo
-/// object from which to retrieve the captured piece.
-
-void Position::undo_ep_move(Move m) {
- Color us, them;
- Square from, to, capsq;
-
- assert(move_is_ok(m));
- assert(move_is_ep(m));
-
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- us = side_to_move();
- them = opposite_color(us);
-
- // Find from, to and captures squares:
- from = move_from(m);
- to = move_to(m);
- capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
-
- assert(to == ep_square());
- assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(to) == pawn_of_color(us));
- assert(piece_on(from) == EMPTY);
- assert(piece_on(capsq) == EMPTY);
-
- // Replace captured piece:
- set_bit(&(byColorBB[them]), capsq);
- set_bit(&(byTypeBB[PAWN]), capsq);
- set_bit(&(byTypeBB[0]), capsq);
- board[capsq] = pawn_of_color(them);
-
- // Remove moving piece from destination square:
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[PAWN]), to);
- clear_bit(&(byTypeBB[0]), to);
- board[to] = EMPTY;
-
- // Replace moving piece at source square:
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[PAWN]), from);
- set_bit(&(byTypeBB[0]), from);
- board[from] = pawn_of_color(us);
-
- // Update piece list:
- pieceList[us][PAWN][index[to]] = from;
- index[from] = index[to];
- pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq;
- index[capsq] = pieceCount[them][PAWN];
-
- // Update piece count:
- pieceCount[them][PAWN]++;
+ assert(is_ok());
}
/// Position::do_null_move makes() a "null move": It switches the side to move
/// and updates the hash key without executing any move on the board.
-void Position::do_null_move(UndoInfo &u) {
+void Position::do_null_move(StateInfo& backupSt) {
+
assert(is_ok());
assert(!is_check());
// Back up the information necessary to undo the null move to the supplied
- // UndoInfo object. In the case of a null move, the only thing we need to
- // remember is the last move made and the en passant square.
- u.lastMove = lastMove;
- u.epSquare = epSquare;
+ // StateInfo object.
+ // Note that differently from normal case here backupSt is actually used as
+ // a backup storage not as a new state to be used.
+ backupSt.key = st->key;
+ backupSt.epSquare = st->epSquare;
+ backupSt.value = st->value;
+ backupSt.previous = st->previous;
+ backupSt.pliesFromNull = st->pliesFromNull;
+ st->previous = &backupSt;
// Save the current key to the history[] array, in order to be able to
- // detect repetition draws:
- history[gamePly] = key;
+ // detect repetition draws.
+ history[gamePly] = st->key;
- // Update the necessary information.
- sideToMove = opposite_color(sideToMove);
- if(epSquare != SQ_NONE)
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
- rule50++;
- gamePly++;
- key ^= zobSideToMove;
+ // Update the necessary information
+ if (st->epSquare != SQ_NONE)
+ st->key ^= zobEp[st->epSquare];
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ st->key ^= zobSideToMove;
+ TT.prefetch(st->key);
- assert(is_ok());
+ sideToMove = opposite_color(sideToMove);
+ st->epSquare = SQ_NONE;
+ st->rule50++;
+ st->pliesFromNull = 0;
+ st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
+ gamePly++;
}
/// Position::undo_null_move() unmakes a "null move".
-void Position::undo_null_move(const UndoInfo &u) {
+void Position::undo_null_move() {
+
assert(is_ok());
assert(!is_check());
- // Restore information from the supplied UndoInfo object:
- lastMove = u.lastMove;
- epSquare = u.epSquare;
- if(epSquare != SQ_NONE)
- key ^= zobEp[epSquare];
+ // Restore information from the our backup StateInfo object
+ StateInfo* backupSt = st->previous;
+ st->key = backupSt->key;
+ st->epSquare = backupSt->epSquare;
+ st->value = backupSt->value;
+ st->previous = backupSt->previous;
+ st->pliesFromNull = backupSt->pliesFromNull;
- // Update the necessary information.
+ // Update the necessary information
sideToMove = opposite_color(sideToMove);
- rule50--;
+ st->rule50--;
gamePly--;
- key ^= zobSideToMove;
+}
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
- assert(is_ok());
+/// Position::see() is a static exchange evaluator: It tries to estimate the
+/// material gain or loss resulting from a move. There are three versions of
+/// 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.
+
+int Position::see(Square to) const {
+
+ assert(square_is_ok(to));
+ return see(SQ_NONE, to);
}
+int Position::see(Move m) const {
-/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are two versions of
-/// this function: One which takes a move as input, and one which takes a
-/// 'from' and a 'to' square. The function does not yet understand promotions
-/// or en passant captures.
+ assert(move_is_ok(m));
+ return see(move_from(m), move_to(m));
+}
+
+int Position::see_sign(Move m) const {
+
+ assert(move_is_ok(m));
+
+ Square from = move_from(m);
+ Square to = move_to(m);
+
+ // Early return if SEE cannot be negative because capturing piece value
+ // is not bigger then captured one.
+ if ( midgame_value_of_piece_on(from) <= midgame_value_of_piece_on(to)
+ && type_of_piece_on(from) != KING)
+ return 1;
+
+ return see(from, to);
+}
int Position::see(Square from, Square to) const {
- // Approximate material values, with pawn = 1:
+
+ // Material values
static const int seeValues[18] = {
- 0, 1, 3, 3, 5, 10, 100, 0, 0, 1, 3, 3, 5, 10, 100, 0, 0, 0
+ 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
+ RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0,
+ 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
+ RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0,
+ 0, 0
};
- Color us, them;
- Piece piece, capture;
- Bitboard attackers, occ, b;
- assert(square_is_ok(from));
+ Bitboard attackers, stmAttackers, b;
+
+ assert(square_is_ok(from) || from == SQ_NONE);
assert(square_is_ok(to));
- // Initialize colors:
- us = color_of_piece_on(from);
- them = opposite_color(us);
-
- // Initialize pieces:
- piece = piece_on(from);
- capture = piece_on(to);
-
- // Find all attackers to the destination square, with the moving piece
- // removed, but possibly an X-ray attacker added behind it:
- occ = occupied_squares();
- clear_bit(&occ, from);
- attackers =
- (rook_attacks_bb(to, occ) & rooks_and_queens()) |
- (bishop_attacks_bb(to, occ) & bishops_and_queens()) |
- (piece_attacks<KNIGHT>(to) & knights()) |
- (piece_attacks<KING>(to) & kings()) |
- (pawn_attacks(WHITE, to) & pawns(BLACK)) |
- (pawn_attacks(BLACK, to) & pawns(WHITE));
- attackers &= occ;
-
- // If the opponent has no attackers, we are finished:
- if((attackers & pieces_of_color(them)) == EmptyBoardBB)
- return seeValues[capture];
+ // Initialize colors
+ Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to)));
+ Color them = opposite_color(us);
+
+ // Initialize pieces
+ Piece piece = piece_on(from);
+ Piece capture = piece_on(to);
+ Bitboard occ = occupied_squares();
+
+ // King cannot be recaptured
+ if (type_of_piece(piece) == KING)
+ return seeValues[capture];
+
+ // Handle en passant moves
+ if (st->epSquare == to && type_of_piece_on(from) == PAWN)
+ {
+ assert(capture == EMPTY);
+
+ Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S);
+ capture = piece_on(capQq);
+ assert(type_of_piece_on(capQq) == PAWN);
+
+ // Remove the captured pawn
+ clear_bit(&occ, capQq);
+ }
+
+ while (true)
+ {
+ // Find all attackers to the destination square, with the moving piece
+ // removed, but possibly an X-ray attacker added behind it.
+ clear_bit(&occ, from);
+ attackers = (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN))
+ | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN))
+ | (attacks_from<KNIGHT>(to) & pieces(KNIGHT))
+ | (attacks_from<KING>(to) & pieces(KING))
+ | (attacks_from<PAWN>(to, WHITE) & pieces(PAWN, BLACK))
+ | (attacks_from<PAWN>(to, BLACK) & pieces(PAWN, WHITE));
+
+ if (from != SQ_NONE)
+ break;
+
+ // If we don't have any attacker we are finished
+ if ((attackers & pieces_of_color(us)) == EmptyBoardBB)
+ return 0;
+
+ // Locate the least valuable attacker to the destination square
+ // and use it to initialize from square.
+ stmAttackers = attackers & pieces_of_color(us);
+ PieceType pt;
+ for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++)
+ assert(pt < KING);
+
+ from = first_1(stmAttackers & pieces(pt));
+ piece = piece_on(from);
+ }
+
+ // If the opponent has no attackers we are finished
+ stmAttackers = attackers & pieces_of_color(them);
+ if (!stmAttackers)
+ return seeValues[capture];
+
+ attackers &= occ; // Remove the moving piece
// The destination square is defended, which makes things rather more
- // difficult to compute. We proceed by building up a "swap list" containing
+ // difficult to compute. We proceed by building up a "swap list" containing
// the material gain or loss at each stop in a sequence of captures to the
- // destianation square, where the sides alternately capture, and always
- // capture with the least valuable piece. After each capture, we look for
+ // 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.
int lastCapturingPieceValue = seeValues[piece];
int swapList[32], n = 1;
swapList[0] = seeValues[capture];
do {
- // Locate the least valuable attacker for the side to move. The loop
- // below looks like it is potentially infinite, but it isn't. We know
- // that the side to move still has at least one attacker left.
- for(pt = PAWN; !(attackers&pieces_of_color_and_type(c, pt)); pt++)
- assert(pt < KING);
-
- // Remove the attacker we just found from the 'attackers' bitboard,
- // and scan for new X-ray attacks behind the attacker:
- b = attackers & pieces_of_color_and_type(c, pt);
- occ ^= (b & -b);
- attackers |=
- (rook_attacks_bb(to, occ) & rooks_and_queens()) |
- (bishop_attacks_bb(to, occ) & bishops_and_queens());
- attackers &= occ;
-
- // Add the new entry to the swap list:
- assert(n < 32);
- swapList[n] = -swapList[n - 1] + lastCapturingPieceValue;
- n++;
-
- // Remember the value of the capturing piece, and change the side to move
- // before beginning the next iteration:
- lastCapturingPieceValue = seeValues[pt];
- c = opposite_color(c);
-
- // Stop after a king capture:
- if(pt == KING && (attackers & pieces_of_color(c))) {
+ // Locate the least valuable attacker for the side to move. The loop
+ // below looks like it is potentially infinite, but it isn't. We know
+ // that the side to move still has at least one attacker left.
+ for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++)
+ assert(pt < KING);
+
+ // Remove the attacker we just found from the 'attackers' bitboard,
+ // and scan for new X-ray attacks behind the attacker.
+ b = stmAttackers & pieces(pt);
+ occ ^= (b & (~b + 1));
+ attackers |= (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN))
+ | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN));
+
+ attackers &= occ;
+
+ // Add the new entry to the swap list
assert(n < 32);
- swapList[n++] = 100;
- break;
- }
- } while(attackers & pieces_of_color(c));
+ swapList[n] = -swapList[n - 1] + lastCapturingPieceValue;
+ n++;
- // 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(--n) swapList[n-1] = Min(-swapList[n], swapList[n-1]);
+ // Remember the value of the capturing piece, and change the side to move
+ // before beginning the next iteration
+ lastCapturingPieceValue = seeValues[pt];
+ c = opposite_color(c);
+ stmAttackers = attackers & pieces_of_color(c);
- return swapList[0];
-}
+ // Stop after a king capture
+ if (pt == KING && stmAttackers)
+ {
+ assert(n < 32);
+ swapList[n++] = QueenValueMidgame*10;
+ break;
+ }
+ } while (stmAttackers);
+ // Having built the swap list, we negamax through it to find the best
+ // achievable score from the point of view of the side to move
+ while (--n)
+ swapList[n-1] = Min(-swapList[n], swapList[n-1]);
-int Position::see(Move m) const {
- assert(move_is_ok(m));
- return see(move_from(m), move_to(m));
+ return swapList[0];
}
/// empty board, white to move, and no castling rights.
void Position::clear() {
- int i, j;
-
- for(i = 0; i < 64; i++) {
- board[i] = EMPTY;
- index[i] = 0;
- }
- for(i = 0; i < 2; i++)
- byColorBB[i] = EmptyBoardBB;
+ st = &startState;
+ memset(st, 0, sizeof(StateInfo));
+ st->epSquare = SQ_NONE;
- for(i = 0; i < 7; i++) {
- byTypeBB[i] = EmptyBoardBB;
- pieceCount[0][i] = pieceCount[1][i] = 0;
- for(j = 0; j < 8; j++)
- pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
- }
+ memset(byColorBB, 0, sizeof(Bitboard) * 2);
+ memset(byTypeBB, 0, sizeof(Bitboard) * 8);
+ memset(pieceCount, 0, sizeof(int) * 2 * 8);
+ memset(index, 0, sizeof(int) * 64);
- checkersBB = EmptyBoardBB;
+ for (int i = 0; i < 64; i++)
+ board[i] = EMPTY;
- lastMove = MOVE_NONE;
+ for (int i = 0; i < 8; i++)
+ for (int j = 0; j < 16; j++)
+ pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
sideToMove = WHITE;
- castleRights = NO_CASTLES;
+ gamePly = 0;
initialKFile = FILE_E;
initialKRFile = FILE_H;
initialQRFile = FILE_A;
- epSquare = SQ_NONE;
- rule50 = 0;
- gamePly = 0;
}
-/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the
+/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the
/// UCI interface code, whenever a non-reversible move is made in a
/// 'position fen <fen> moves m1 m2 ...' command. This makes it possible
/// for the program to handle games of arbitrary length, as long as the GUI
/// handles draws by the 50 move rule correctly.
void Position::reset_game_ply() {
+
gamePly = 0;
}
/// updating the board array, bitboards, and piece counts.
void Position::put_piece(Piece p, Square s) {
+
Color c = color_of_piece(p);
PieceType pt = type_of_piece(p);
set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares.
pieceCount[c][pt]++;
-
- if(pt == KING)
- kingSquare[c] = s;
}
/// Used when setting castling rights during parsing of FEN strings.
void Position::allow_oo(Color c) {
- castleRights |= (1 + int(c));
+
+ st->castleRights |= (1 + int(c));
}
/// Used when setting castling rights during parsing of FEN strings.
void Position::allow_ooo(Color c) {
- castleRights |= (4 + 4*int(c));
+
+ st->castleRights |= (4 + 4*int(c));
}
-/// Position::compute_key() computes the hash key of the position. The hash
+/// Position::compute_key() computes the hash key of the position. The hash
/// key is usually updated incrementally as moves are made and unmade, the
/// compute_key() function is only used when a new position is set up, and
/// to verify the correctness of the hash key when running in debug mode.
Key Position::compute_key() const {
+
Key result = Key(0ULL);
- for(Square s = SQ_A1; s <= SQ_H8; s++)
- if(square_is_occupied(s))
- result ^=
- zobrist[color_of_piece_on(s)][type_of_piece_on(s)][s];
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ if (square_is_occupied(s))
+ result ^= zobrist[color_of_piece_on(s)][type_of_piece_on(s)][s];
- if(ep_square() != SQ_NONE)
- result ^= zobEp[ep_square()];
- result ^= zobCastle[castleRights];
- if(side_to_move() == BLACK) result ^= zobSideToMove;
+ if (ep_square() != SQ_NONE)
+ result ^= zobEp[ep_square()];
+
+ result ^= zobCastle[st->castleRights];
+ if (side_to_move() == BLACK)
+ result ^= zobSideToMove;
return result;
}
-/// Position::compute_pawn_key() computes the hash key of the position. The
+/// Position::compute_pawn_key() computes the hash key of the position. The
/// hash key is usually updated incrementally as moves are made and unmade,
/// the compute_pawn_key() function is only used when a new position is set
/// up, and to verify the correctness of the pawn hash key when running in
/// debug mode.
Key Position::compute_pawn_key() const {
+
Key result = Key(0ULL);
Bitboard b;
Square s;
- for(Color c = WHITE; c <= BLACK; c++) {
- b = pawns(c);
- while(b) {
- s = pop_1st_bit(&b);
- result ^= zobrist[c][PAWN][s];
- }
+ for (Color c = WHITE; c <= BLACK; c++)
+ {
+ b = pieces(PAWN, c);
+ while (b)
+ {
+ s = pop_1st_bit(&b);
+ result ^= zobrist[c][PAWN][s];
+ }
}
return result;
}
/// debug mode.
Key Position::compute_material_key() const {
+
Key result = Key(0ULL);
- for(Color c = WHITE; c <= BLACK; c++)
- for(PieceType pt = PAWN; pt <= QUEEN; pt++) {
- int count = piece_count(c, pt);
- for(int i = 0; i <= count; i++)
- result ^= zobMaterial[c][pt][i];
- }
+ for (Color c = WHITE; c <= BLACK; c++)
+ for (PieceType pt = PAWN; pt <= QUEEN; pt++)
+ {
+ int count = piece_count(c, pt);
+ for (int i = 0; i < count; i++)
+ result ^= zobMaterial[c][pt][i];
+ }
return result;
}
-/// Position::compute_mg_value() and Position::compute_eg_value() compute the
-/// incremental scores for the middle game and the endgame. These functions
-/// are used to initialize the incremental scores when a new position is set
-/// up, and to verify that the scores are correctly updated by do_move
-/// and undo_move when the program is running in debug mode.
+/// Position::compute_value() compute the incremental scores for the middle
+/// game and the endgame. These functions are used to initialize the incremental
+/// scores when a new position is set up, and to verify that the scores are correctly
+/// updated by do_move and undo_move when the program is running in debug mode.
+Score Position::compute_value() const {
-Value Position::compute_mg_value() const {
- Value result = Value(0);
+ Score result = make_score(0, 0);
Bitboard b;
Square s;
- for(Color c = WHITE; c <= BLACK; c++)
- for(PieceType pt = PAWN; pt <= KING; pt++) {
- b = pieces_of_color_and_type(c, pt);
- while(b) {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += mg_pst(c, pt, s);
+ for (Color c = WHITE; c <= BLACK; c++)
+ for (PieceType pt = PAWN; pt <= KING; pt++)
+ {
+ b = pieces(pt, c);
+ while (b)
+ {
+ s = pop_1st_bit(&b);
+ assert(piece_on(s) == piece_of_color_and_type(c, pt));
+ result += pst(c, pt, s);
+ }
}
- }
- result += (side_to_move() == WHITE)?
- (TempoValueMidgame / 2) : -(TempoValueMidgame / 2);
- return result;
-}
-
-Value Position::compute_eg_value() const {
- Value result = Value(0);
- Bitboard b;
- Square s;
- for(Color c = WHITE; c <= BLACK; c++)
- for(PieceType pt = PAWN; pt <= KING; pt++) {
- b = pieces_of_color_and_type(c, pt);
- while(b) {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += eg_pst(c, pt, s);
- }
- }
- result += (side_to_move() == WHITE)?
- (TempoValueEndgame / 2) : -(TempoValueEndgame / 2);
+ result += (side_to_move() == WHITE ? TempoValue / 2 : -TempoValue / 2);
return result;
}
/// Position::compute_non_pawn_material() computes the total non-pawn middle
-/// game material score for the given side. Material scores are updated
+/// game material score for the given side. Material scores are updated
/// incrementally during the search, this function is only used while
/// initializing a new Position object.
Value Position::compute_non_pawn_material(Color c) const {
+
Value result = Value(0);
- Square s;
- for(PieceType pt = KNIGHT; pt <= QUEEN; pt++) {
- Bitboard b = pieces_of_color_and_type(c, pt);
- while(b) {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += piece_value_midgame(pt);
- }
+ for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
+ {
+ Bitboard b = pieces(pt, c);
+ while (b)
+ {
+ assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt));
+ pop_1st_bit(&b);
+ result += piece_value_midgame(pt);
+ }
}
return result;
}
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated. Note that this function is currently very
-/// slow, and shouldn't be used frequently inside the search.
-
-bool Position::is_mate() {
- if(is_check()) {
- MovePicker mp = MovePicker(*this, false, MOVE_NONE, MOVE_NONE, MOVE_NONE,
- MOVE_NONE, Depth(0));
- return mp.get_next_move() == MOVE_NONE;
- }
- else
- return false;
-}
-
-
/// Position::is_draw() tests whether the position is drawn by material,
-/// repetition, or the 50 moves rule. It does not detect stalemates, this
+/// repetition, or the 50 moves rule. It does not detect stalemates, this
/// must be done by the search.
+// FIXME: Currently we are not handling 50 move rule correctly when in check
bool Position::is_draw() const {
+
// Draw by material?
- if(!pawns() &&
- non_pawn_material(WHITE) + non_pawn_material(BLACK)
- <= BishopValueMidgame)
- return true;
+ if ( !pieces(PAWN)
+ && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame))
+ return true;
// Draw by the 50 moves rule?
- if(rule50 > 100 || (rule50 == 100 && !is_check()))
- return true;
+ if (st->rule50 > 100 || (st->rule50 == 100 && !is_check()))
+ return true;
// Draw by repetition?
- for(int i = 2; i < Min(gamePly, rule50); i += 2)
- if(history[gamePly - i] == key)
- return true;
+ for (int i = 4; i <= Min(Min(gamePly, st->rule50), st->pliesFromNull); i += 2)
+ if (history[gamePly - i] == st->key)
+ return true;
return false;
}
+/// Position::is_mate() returns true or false depending on whether the
+/// side to move is checkmated.
+
+bool Position::is_mate() const {
+
+ MoveStack moves[256];
+ return is_check() && (generate_moves(*this, moves, false) == moves);
+}
+
+
/// Position::has_mate_threat() tests whether a given color has a mate in one
-/// from the current position. This function is quite slow, but it doesn't
-/// matter, because it is currently only called from PV nodes, which are rare.
+/// from the current position.
bool Position::has_mate_threat(Color c) {
- UndoInfo u1, u2;
- Color stm = side_to_move();
- // The following lines are useless and silly, but prevents gcc from
- // emitting a stupid warning stating that u1.lastMove and u1.epSquare might
- // be used uninitialized.
- u1.lastMove = lastMove;
- u1.epSquare = epSquare;
+ StateInfo st1, st2;
+ Color stm = side_to_move();
- if(is_check())
- return false;
+ if (is_check())
+ return false;
// If the input color is not equal to the side to move, do a null move
- if(c != stm) do_null_move(u1);
+ if (c != stm)
+ do_null_move(st1);
MoveStack mlist[120];
- int count;
bool result = false;
+ Bitboard pinned = pinned_pieces(sideToMove);
+
+ // Generate pseudo-legal non-capture and capture check moves
+ MoveStack* last = generate_non_capture_checks(*this, mlist);
+ last = generate_captures(*this, last);
- // Generate legal moves
- count = generate_legal_moves(*this, mlist);
+ // Loop through the moves, and see if one of them is mate
+ for (MoveStack* cur = mlist; cur != last; cur++)
+ {
+ Move move = cur->move;
+ if (!pl_move_is_legal(move, pinned))
+ continue;
- // Loop through the moves, and see if one of them is mate.
- for(int i = 0; i < count; i++) {
- do_move(mlist[i].move, u2);
- if(is_mate()) result = true;
- undo_move(mlist[i].move, u2);
+ do_move(move, st2);
+ if (is_mate())
+ result = true;
+
+ undo_move(move);
}
// Undo null move, if necessary
- if(c != stm) undo_null_move(u1);
+ if (c != stm)
+ undo_null_move();
return result;
}
void Position::init_zobrist() {
- for(int i = 0; i < 2; i++)
- for(int j = 0; j < 8; j++)
- for(int k = 0; k < 64; k++)
- zobrist[i][j][k] = Key(genrand_int64());
+ for (int i = 0; i < 2; i++)
+ for (int j = 0; j < 8; j++)
+ for (int k = 0; k < 64; k++)
+ zobrist[i][j][k] = Key(genrand_int64());
- for(int i = 0; i < 64; i++)
- zobEp[i] = Key(genrand_int64());
+ for (int i = 0; i < 64; i++)
+ zobEp[i] = Key(genrand_int64());
- for(int i = 0; i < 16; i++)
- zobCastle[i] = genrand_int64();
+ for (int i = 0; i < 16; i++)
+ zobCastle[i] = genrand_int64();
zobSideToMove = genrand_int64();
- for(int i = 0; i < 2; i++)
- for(int j = 0; j < 8; j++)
- for(int k = 0; k < 16; k++)
- zobMaterial[i][j][k] = (k > 0)? Key(genrand_int64()) : Key(0LL);
+ for (int i = 0; i < 2; i++)
+ for (int j = 0; j < 8; j++)
+ for (int k = 0; k < 8; k++)
+ zobMaterial[i][j][k] = Key(genrand_int64());
+
+ for (int i = 0; i < 8; i++)
+ zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL);
- for(int i = 0; i < 16; i++)
- zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL);
+ zobExclusion = genrand_int64();
}
/// and changing the sign of the corresponding white scores.
void Position::init_piece_square_tables() {
+
int r = get_option_value_int("Randomness"), i;
- for(Square s = SQ_A1; s <= SQ_H8; s++) {
- for(Piece p = WP; p <= WK; p++) {
- i = (r == 0)? 0 : (genrand_int32() % (r*2) - r);
- MgPieceSquareTable[p][s] = Value(MgPST[p][s] + i);
- EgPieceSquareTable[p][s] = Value(EgPST[p][s] + i);
- }
- }
- for(Square s = SQ_A1; s <= SQ_H8; s++)
- for(Piece p = BP; p <= BK; p++) {
- MgPieceSquareTable[p][s] = -MgPieceSquareTable[p-8][flip_square(s)];
- EgPieceSquareTable[p][s] = -EgPieceSquareTable[p-8][flip_square(s)];
- }
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ for (Piece p = WP; p <= WK; p++)
+ {
+ i = (r == 0)? 0 : (genrand_int32() % (r*2) - r);
+ PieceSquareTable[p][s] = make_score(MgPST[p][s] + i, EgPST[p][s] + i);
+ }
+
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ for (Piece p = BP; p <= BK; p++)
+ PieceSquareTable[p][s] = -PieceSquareTable[p-8][flip_square(s)];
}
/// Position::flipped_copy() makes a copy of the input position, but with
-/// the white and black sides reversed. This is only useful for debugging,
+/// the white and black sides reversed. This is only useful for debugging,
/// especially for finding evaluation symmetry bugs.
-void Position::flipped_copy(const Position &pos) {
+void Position::flipped_copy(const Position& pos) {
+
assert(pos.is_ok());
clear();
// Board
- for(Square s = SQ_A1; s <= SQ_H8; s++)
- if(!pos.square_is_empty(s))
- put_piece(Piece(int(pos.piece_on(s)) ^ 8), flip_square(s));
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ if (!pos.square_is_empty(s))
+ put_piece(Piece(int(pos.piece_on(s)) ^ 8), flip_square(s));
// Side to move
sideToMove = opposite_color(pos.side_to_move());
// Castling rights
- if(pos.can_castle_kingside(WHITE)) allow_oo(BLACK);
- if(pos.can_castle_queenside(WHITE)) allow_ooo(BLACK);
- if(pos.can_castle_kingside(BLACK)) allow_oo(WHITE);
- if(pos.can_castle_queenside(BLACK)) allow_ooo(WHITE);
+ if (pos.can_castle_kingside(WHITE)) allow_oo(BLACK);
+ if (pos.can_castle_queenside(WHITE)) allow_ooo(BLACK);
+ if (pos.can_castle_kingside(BLACK)) allow_oo(WHITE);
+ if (pos.can_castle_queenside(BLACK)) allow_ooo(WHITE);
- initialKFile = pos.initialKFile;
+ initialKFile = pos.initialKFile;
initialKRFile = pos.initialKRFile;
initialQRFile = pos.initialQRFile;
- for(Square sq = SQ_A1; sq <= SQ_H8; sq++)
- castleRightsMask[sq] = ALL_CASTLES;
- castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO|WHITE_OOO);
- castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO|BLACK_OOO);
- castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO;
- castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO;
- castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO;
- castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
+ for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
+ castleRightsMask[sq] = ALL_CASTLES;
+
+ castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO | WHITE_OOO);
+ castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO | BLACK_OOO);
+ castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO;
+ castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO;
+ castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO;
+ castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
// En passant square
- if(pos.epSquare != SQ_NONE)
- epSquare = flip_square(pos.epSquare);
+ if (pos.st->epSquare != SQ_NONE)
+ st->epSquare = flip_square(pos.st->epSquare);
// Checkers
find_checkers();
// Hash keys
- key = compute_key();
- pawnKey = compute_pawn_key();
- materialKey = compute_material_key();
+ st->key = compute_key();
+ st->pawnKey = compute_pawn_key();
+ st->materialKey = compute_material_key();
// Incremental scores
- mgValue = compute_mg_value();
- egValue = compute_eg_value();
+ st->value = compute_value();
// Material
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
+ st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
assert(is_ok());
}
static const bool debugNonPawnMaterial = false;
static const bool debugPieceCounts = false;
static const bool debugPieceList = false;
+ static const bool debugCastleSquares = false;
if (failedStep) *failedStep = 1;
// Side to move OK?
- if(!color_is_ok(side_to_move()))
- return false;
+ if (!color_is_ok(side_to_move()))
+ return false;
// Are the king squares in the position correct?
if (failedStep) (*failedStep)++;
- if(piece_on(king_square(WHITE)) != WK)
- return false;
+ if (piece_on(king_square(WHITE)) != WK)
+ return false;
if (failedStep) (*failedStep)++;
- if(piece_on(king_square(BLACK)) != BK)
- return false;
+ if (piece_on(king_square(BLACK)) != BK)
+ return false;
// Castle files OK?
if (failedStep) (*failedStep)++;
- if(!file_is_ok(initialKRFile))
- return false;
- if(!file_is_ok(initialQRFile))
- return false;
+ if (!file_is_ok(initialKRFile))
+ return false;
+
+ if (!file_is_ok(initialQRFile))
+ return false;
// Do both sides have exactly one king?
if (failedStep) (*failedStep)++;
- if(debugKingCount) {
- int kingCount[2] = {0, 0};
- for(Square s = SQ_A1; s <= SQ_H8; s++)
- if(type_of_piece_on(s) == KING)
- kingCount[color_of_piece_on(s)]++;
- if(kingCount[0] != 1 || kingCount[1] != 1)
- return false;
+ if (debugKingCount)
+ {
+ int kingCount[2] = {0, 0};
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ if (type_of_piece_on(s) == KING)
+ kingCount[color_of_piece_on(s)]++;
+
+ if (kingCount[0] != 1 || kingCount[1] != 1)
+ return false;
}
// Can the side to move capture the opponent's king?
if (failedStep) (*failedStep)++;
- if(debugKingCapture) {
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square ksq = king_square(them);
- if(square_is_attacked(ksq, us))
- return false;
+ if (debugKingCapture)
+ {
+ Color us = side_to_move();
+ Color them = opposite_color(us);
+ Square ksq = king_square(them);
+ if (attackers_to(ksq) & pieces_of_color(us))
+ return false;
}
// Is there more than 2 checkers?
if (failedStep) (*failedStep)++;
- if(debugCheckerCount && count_1s(checkersBB) > 2)
- return false;
+ if (debugCheckerCount && count_1s(st->checkersBB) > 2)
+ return false;
// Bitboards OK?
if (failedStep) (*failedStep)++;
- if(debugBitboards) {
- // The intersection of the white and black pieces must be empty:
- if((pieces_of_color(WHITE) & pieces_of_color(BLACK))
- != EmptyBoardBB)
- return false;
-
- // The union of the white and black pieces must be equal to all
- // occupied squares:
- if((pieces_of_color(WHITE) | pieces_of_color(BLACK))
- != occupied_squares())
- return false;
+ if (debugBitboards)
+ {
+ // The intersection of the white and black pieces must be empty
+ if ((pieces_of_color(WHITE) & pieces_of_color(BLACK)) != EmptyBoardBB)
+ return false;
- // Separate piece type bitboards must have empty intersections:
- for(PieceType p1 = PAWN; p1 <= KING; p1++)
- for(PieceType p2 = PAWN; p2 <= KING; p2++)
- if(p1 != p2 && (pieces_of_type(p1) & pieces_of_type(p2)))
+ // The union of the white and black pieces must be equal to all
+ // occupied squares
+ if ((pieces_of_color(WHITE) | pieces_of_color(BLACK)) != occupied_squares())
return false;
+
+ // Separate piece type bitboards must have empty intersections
+ for (PieceType p1 = PAWN; p1 <= KING; p1++)
+ for (PieceType p2 = PAWN; p2 <= KING; p2++)
+ if (p1 != p2 && (pieces(p1) & pieces(p2)))
+ return false;
}
// En passant square OK?
if (failedStep) (*failedStep)++;
- if(ep_square() != SQ_NONE) {
- // 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)
- return false;
+ if (ep_square() != SQ_NONE)
+ {
+ // 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)
+ return false;
}
// Hash key OK?
if (failedStep) (*failedStep)++;
- if(debugKey && key != compute_key())
- return false;
+ if (debugKey && st->key != compute_key())
+ return false;
// Pawn hash key OK?
if (failedStep) (*failedStep)++;
- if(debugPawnKey && pawnKey != compute_pawn_key())
- return false;
+ if (debugPawnKey && st->pawnKey != compute_pawn_key())
+ return false;
// Material hash key OK?
if (failedStep) (*failedStep)++;
- if(debugMaterialKey && materialKey != compute_material_key())
- return false;
+ if (debugMaterialKey && st->materialKey != compute_material_key())
+ return false;
// Incremental eval OK?
if (failedStep) (*failedStep)++;
- if(debugIncrementalEval) {
- if(mgValue != compute_mg_value())
+ if (debugIncrementalEval && st->value != compute_value())
return false;
- if(egValue != compute_eg_value())
- return false;
- }
// Non-pawn material OK?
if (failedStep) (*failedStep)++;
- if(debugNonPawnMaterial) {
- if(npMaterial[WHITE] != compute_non_pawn_material(WHITE))
- return false;
- if(npMaterial[BLACK] != compute_non_pawn_material(BLACK))
- return false;
+ if (debugNonPawnMaterial)
+ {
+ if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
+ return false;
+
+ if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ return false;
}
// Piece counts OK?
if (failedStep) (*failedStep)++;
- if(debugPieceCounts)
- for(Color c = WHITE; c <= BLACK; c++)
- for(PieceType pt = PAWN; pt <= KING; pt++)
- if(pieceCount[c][pt] != count_1s(pieces_of_color_and_type(c, pt)))
- return false;
+ if (debugPieceCounts)
+ for (Color c = WHITE; c <= BLACK; c++)
+ for (PieceType pt = PAWN; pt <= KING; pt++)
+ if (pieceCount[c][pt] != count_1s(pieces(pt, c)))
+ return false;
if (failedStep) (*failedStep)++;
- if(debugPieceList) {
- for(Color c = WHITE; c <= BLACK; c++)
- for(PieceType pt = PAWN; pt <= KING; pt++)
- for(int i = 0; i < pieceCount[c][pt]; i++) {
- if(piece_on(piece_list(c, pt, i)) !=
- piece_of_color_and_type(c, pt))
- return false;
- if(index[piece_list(c, pt, i)] != i)
- return false;
- }
+ if (debugPieceList)
+ {
+ for (Color c = WHITE; c <= BLACK; c++)
+ for (PieceType pt = PAWN; pt <= KING; pt++)
+ for (int i = 0; i < pieceCount[c][pt]; i++)
+ {
+ if (piece_on(piece_list(c, pt, i)) != piece_of_color_and_type(c, pt))
+ return false;
+
+ if (index[piece_list(c, pt, i)] != i)
+ return false;
+ }
}
+
+ if (failedStep) (*failedStep)++;
+ if (debugCastleSquares) {
+ for (Color c = WHITE; c <= BLACK; c++) {
+ if (can_castle_kingside(c) && piece_on(initial_kr_square(c)) != piece_of_color_and_type(c, ROOK))
+ return false;
+ if (can_castle_queenside(c) && piece_on(initial_qr_square(c)) != piece_of_color_and_type(c, ROOK))
+ return false;
+ }
+ if (castleRightsMask[initial_kr_square(WHITE)] != (ALL_CASTLES ^ WHITE_OO))
+ return false;
+ if (castleRightsMask[initial_qr_square(WHITE)] != (ALL_CASTLES ^ WHITE_OOO))
+ return false;
+ if (castleRightsMask[initial_kr_square(BLACK)] != (ALL_CASTLES ^ BLACK_OO))
+ return false;
+ if (castleRightsMask[initial_qr_square(BLACK)] != (ALL_CASTLES ^ BLACK_OOO))
+ return false;
+ }
+
if (failedStep) *failedStep = 0;
return true;
}
projects / stockfish / blobdiff