/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <fstream>
#include <iostream>
+#include "bitcount.h"
#include "mersenne.h"
#include "movegen.h"
#include "movepick.h"
#include "san.h"
#include "ucioption.h"
+using std::string;
+
////
//// Variables
////
-extern SearchStack EmptySearchStack;
-
int Position::castleRightsMask[64];
Key Position::zobrist[2][8][64];
copy(pos);
}
-Position::Position(const std::string& fen) {
+Position::Position(const string& fen) {
from_fen(fen);
}
/// string. This function is not very robust - make sure that input FENs are
/// correct (this is assumed to be the responsibility of the GUI).
-void Position::from_fen(const std::string& fen) {
+void Position::from_fen(const string& fen) {
- static const std::string pieceLetters = "KQRBNPkqrbnp";
+ static const string pieceLetters = "KQRBNPkqrbnp";
static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP };
clear();
continue;
}
size_t idx = pieceLetters.find(fen[i]);
- if (idx == std::string::npos)
+ if (idx == string::npos)
{
std::cout << "Error in FEN at character " << i << std::endl;
return;
i++;
// En passant square
- if ( i < fen.length() - 2
+ if ( i <= fen.length() - 2
&& (fen[i] >= 'a' && fen[i] <= 'h')
&& (fen[i+1] == '3' || fen[i+1] == '6'))
st->epSquare = square_from_string(fen.substr(i, 2));
st->materialKey = compute_material_key();
st->mgValue = compute_value<MidGame>();
st->egValue = compute_value<EndGame>();
- 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);
}
/// 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--)
void Position::print(Move m) const {
- static const std::string pieceLetters = " PNBRQK PNBRQK .";
+ static const string pieceLetters = " PNBRQK PNBRQK .";
// Check for reentrancy, as example when called from inside
// MovePicker that is used also here in move_to_san()
std::cout << std::endl;
if (m != MOVE_NONE)
{
- std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
+ string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
std::cout << "Move is: " << col << move_to_san(*this, m) << std::endl;
}
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
/// Position::copy() creates a copy of the input position.
-void Position::copy(const Position &pos) {
+void Position::copy(const Position& pos) {
memcpy(this, &pos, sizeof(Position));
+ saveState(); // detach and copy state info
}
}
/// Position::attacks_to() computes a bitboard containing all pieces which
-/// attacks a given square. There are two versions of this function: One
-/// which finds attackers of both colors, and one which only finds the
-/// attackers for one side.
+/// attacks a given square.
Bitboard Position::attacks_to(Square s) const {
bool Position::pl_move_is_legal(Move m) const {
- return pl_move_is_legal(m, pinned_pieces(side_to_move()));
+ // If we're in check, all pseudo-legal moves are legal, because our
+ // check evasion generator only generates true legal moves.
+ return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move()));
}
bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
assert(is_ok());
assert(move_is_ok(m));
assert(pinned == pinned_pieces(side_to_move()));
-
- // If we're in check, all pseudo-legal moves are legal, because our
- // check evasion generator only generates true legal moves.
- if (is_check())
- return true;
+ assert(!is_check());
// Castling moves are checked for legality during move generation.
if (move_is_castle(m))
if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check?
return true;
- if ( bit_is_set(dcCandidates, from) // Discovered check?
+ if ( dcCandidates // Discovered check?
+ && bit_is_set(dcCandidates, from)
&& (direction_between_squares(from, ksq) != direction_between_squares(to, ksq)))
return true;
- if (move_promotion(m)) // Promotion with check?
+ if (move_is_promotion(m)) // Promotion with check?
{
Bitboard b = occupied_squares();
clear_bit(&b, from);
- switch (move_promotion(m))
+ switch (move_promotion_piece(m))
{
case KNIGHT:
return bit_is_set(piece_attacks<KNIGHT>(to), ksq);
}
return false;
+ // Test discovered check and normal check according to piece type
case KNIGHT:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<KNIGHT>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || bit_is_set(piece_attacks<KNIGHT>(ksq), to);
case BISHOP:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<BISHOP>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks<BISHOP>(ksq), to));
case ROOK:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<ROOK>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || (direction_is_straight(ksq, to) && bit_is_set(piece_attacks<ROOK>(ksq), to));
case QUEEN:
// Discovered checks are impossible!
assert(!bit_is_set(dcCandidates, from));
- return bit_is_set(piece_attacks<QUEEN>(ksq), to); // Normal check?
+ return ( (direction_is_straight(ksq, to) && bit_is_set(piece_attacks<ROOK>(ksq), to))
+ || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks<BISHOP>(ksq), to)));
case KING:
// Discovered check?
}
-/// Position::move_is_capture() tests whether a move from the current
-/// position is a capture. Move must not be MOVE_NONE.
-
-bool Position::move_is_capture(Move m) const {
-
- assert(m != MOVE_NONE);
-
- return ( !square_is_empty(move_to(m))
- && (color_of_piece_on(move_to(m)) != color_of_piece_on(move_from(m)))
- )
- || move_is_ep(m);
-}
-
-
/// Position::update_checkers() udpates chekers info given the move. It is called
/// in do_move() and is faster then find_checkers().
const bool Rook = (Piece == QUEEN || Piece == ROOK);
const bool Slider = Bishop || Rook;
+ // Direct checks
if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to))
|| (Rook && bit_is_set(RookPseudoAttacks[ksq], to)))
&& bit_is_set(piece_attacks<Piece>(ksq), to)) // slow, try to early skip
&& bit_is_set(piece_attacks<Piece>(ksq), to))
set_bit(pCheckersBB, to);
+ // Discovery checks
if (Piece != QUEEN && bit_is_set(dcCandidates, from))
{
if (Piece != ROOK)
int castleRights, rule50;
Square epSquare;
Value mgValue, egValue;
+ Value npMaterial[2];
};
memcpy(&newSt, st, sizeof(ReducedStateInfo));
if (move_is_castle(m))
do_castle_move(m);
- else if (move_promotion(m))
+ else if (move_is_promotion(m))
do_promotion_move(m);
else if (move_is_ep(m))
do_ep_move(m);
assert(color_of_piece_on(from) == us);
assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY);
- PieceType piece = type_of_piece_on(from);
+ Piece piece = piece_on(from);
+ PieceType pt = type_of_piece(piece);
st->capture = type_of_piece_on(to);
if (st->capture)
- do_capture_move(m, st->capture, them, to);
+ do_capture_move(st->capture, them, to);
// Move the piece
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[piece]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[piece]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+ Bitboard move_bb = make_move_bb(from, to);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[pt]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
+
board[to] = board[from];
board[from] = EMPTY;
// Update hash key
- st->key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to];
+ st->key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
// Update incremental scores
- st->mgValue -= pst<MidGame>(us, piece, from);
- st->mgValue += pst<MidGame>(us, piece, to);
- st->egValue -= pst<EndGame>(us, piece, from);
- st->egValue += pst<EndGame>(us, piece, to);
+ st->mgValue += pst_delta<MidGame>(piece, from, to);
+ st->egValue += pst_delta<EndGame>(piece, from, to);
// If the moving piece was a king, update the king square
- if (piece == KING)
+ if (pt == KING)
kingSquare[us] = to;
// Reset en passant square
}
// If the moving piece was a pawn do some special extra work
- if (piece == PAWN)
+ if (pt == PAWN)
{
// Reset rule 50 draw counter
st->rule50 = 0;
}
// Update piece lists
- pieceList[us][piece][index[from]] = to;
+ pieceList[us][pt][index[from]] = to;
index[to] = index[from];
- // Update castle rights
- st->key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[from];
- st->castleRights &= castleRightsMask[to];
- st->key ^= zobCastle[st->castleRights];
+ // Update castle rights, try to shortcut a common case
+ if ((castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES)
+ {
+ st->key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[from];
+ st->castleRights &= castleRightsMask[to];
+ st->key ^= zobCastle[st->castleRights];
+ }
// Update checkers bitboard, piece must be already moved
st->checkersBB = EmptyBoardBB;
Square ksq = king_square(them);
- switch (piece)
+ switch (pt)
{
case PAWN: update_checkers<PAWN>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
case KNIGHT: update_checkers<KNIGHT>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
/// Position::do_capture_move() is a private method used to update captured
/// piece info. It is called from the main Position::do_move function.
-void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) {
+void Position::do_capture_move(PieceType capture, Color them, Square to) {
assert(capture != KING);
// Remove captured piece
clear_bit(&(byColorBB[them]), to);
clear_bit(&(byTypeBB[capture]), to);
+ clear_bit(&(byTypeBB[0]), to);
// Update hash key
st->key ^= zobrist[them][capture][to];
st->mgValue -= pst<MidGame>(them, capture, to);
st->egValue -= pst<EndGame>(them, capture, to);
- assert(!move_promotion(m) || capture != PAWN);
-
// Update material
if (capture != PAWN)
- npMaterial[them] -= piece_value_midgame(capture);
+ st->npMaterial[them] -= piece_value_midgame(capture);
// Update material hash key
st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares
// 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] = piece_of_color_and_type(us, KING);
- board[rto] = piece_of_color_and_type(us, ROOK);
+ board[kto] = king;
+ board[rto] = rook;
// Update king square
kingSquare[us] = kto;
index[rto] = tmp;
// Update incremental scores
- st->mgValue -= pst<MidGame>(us, KING, kfrom);
- st->mgValue += pst<MidGame>(us, KING, kto);
- st->egValue -= pst<EndGame>(us, KING, kfrom);
- st->egValue += pst<EndGame>(us, KING, kto);
- st->mgValue -= pst<MidGame>(us, ROOK, rfrom);
- st->mgValue += pst<MidGame>(us, ROOK, rto);
- st->egValue -= pst<EndGame>(us, ROOK, rfrom);
- st->egValue += pst<EndGame>(us, ROOK, rto);
+ st->mgValue += pst_delta<MidGame>(king, kfrom, kto);
+ st->egValue += pst_delta<EndGame>(king, kfrom, kto);
+ st->mgValue += pst_delta<MidGame>(rook, rfrom, rto);
+ st->egValue += pst_delta<EndGame>(rook, rfrom, rto);
// Update hash key
st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
assert(is_ok());
assert(move_is_ok(m));
- assert(move_promotion(m));
+ assert(move_is_promotion(m));
us = side_to_move();
them = opposite_color(us);
st->capture = type_of_piece_on(to);
if (st->capture)
- do_capture_move(m, st->capture, them, to);
+ do_capture_move(st->capture, them, to);
// Remove pawn
clear_bit(&(byColorBB[us]), from);
board[from] = EMPTY;
// Insert promoted piece
- promotion = move_promotion(m);
+ promotion = move_promotion_piece(m);
assert(promotion >= KNIGHT && promotion <= QUEEN);
set_bit(&(byColorBB[us]), to);
set_bit(&(byTypeBB[promotion]), to);
st->egValue += pst<EndGame>(us, promotion, to);
// Update material
- npMaterial[us] += piece_value_midgame(promotion);
+ st->npMaterial[us] += piece_value_midgame(promotion);
// Clear the en passant square
if (st->epSquare != SQ_NONE)
assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
- // Remove captured piece
+ // Remove captured pawn
clear_bit(&(byColorBB[them]), capsq);
clear_bit(&(byTypeBB[PAWN]), capsq);
clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares
board[capsq] = EMPTY;
- // Remove moving piece from source square
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[PAWN]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
-
- // Put moving piece on destination square
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[PAWN]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+ // Move capturing pawn
+ Bitboard move_bb = make_move_bb(from, to);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[PAWN]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
board[to] = board[from];
board[from] = EMPTY;
st->pawnKey ^= zobrist[them][PAWN][capsq];
// Update incremental scores
+ Piece pawn = piece_of_color_and_type(us, PAWN);
+ st->mgValue += pst_delta<MidGame>(pawn, from, to);
+ st->egValue += pst_delta<EndGame>(pawn, from, to);
st->mgValue -= pst<MidGame>(them, PAWN, capsq);
- st->mgValue -= pst<MidGame>(us, PAWN, from);
- st->mgValue += pst<MidGame>(us, PAWN, to);
st->egValue -= pst<EndGame>(them, PAWN, capsq);
- st->egValue -= pst<EndGame>(us, PAWN, from);
- st->egValue += pst<EndGame>(us, PAWN, to);
// Reset en passant square
st->epSquare = SQ_NONE;
if (move_is_castle(m))
undo_castle_move(m);
- else if (move_promotion(m))
+ else if (move_is_promotion(m))
undo_promotion_move(m);
else if (move_is_ep(m))
undo_ep_move(m);
assert(color_of_piece_on(to) == us);
// Put the piece back at the source square
+ Bitboard move_bb = make_move_bb(to, from);
piece = type_of_piece_on(to);
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[piece]), from);
- set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[piece]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
board[from] = piece_of_color_and_type(us, piece);
- // Clear the destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[piece]), to);
- clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
-
// If the moving piece was a king, update the king square
if (piece == KING)
kingSquare[us] = from;
{
assert(st->capture != KING);
- // Replace the captured piece
+ // Restore the captured piece
set_bit(&(byColorBB[them]), to);
set_bit(&(byTypeBB[st->capture]), to);
set_bit(&(byTypeBB[0]), to);
board[to] = piece_of_color_and_type(them, st->capture);
- // Update material
- if (st->capture != PAWN)
- npMaterial[them] += piece_value_midgame(st->capture);
-
// Update piece list
pieceList[them][st->capture][pieceCount[them][st->capture]] = to;
index[to] = pieceCount[them][st->capture];
PieceType promotion;
assert(move_is_ok(m));
- assert(move_promotion(m));
+ assert(move_is_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,
assert(piece_on(from) == EMPTY);
// Remove promoted piece
- promotion = move_promotion(m);
+ promotion = move_promotion_piece(m);
assert(piece_on(to)==piece_of_color_and_type(us, promotion));
assert(promotion >= KNIGHT && promotion <= QUEEN);
clear_bit(&(byColorBB[us]), to);
set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
board[from] = piece_of_color_and_type(us, PAWN);
- // Update material
- npMaterial[us] -= piece_value_midgame(promotion);
-
// Update piece list
pieceList[us][PAWN][pieceCount[us][PAWN]] = from;
index[from] = pieceCount[us][PAWN];
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
board[to] = piece_of_color_and_type(them, st->capture);
- // Update material. Because the move is a promotion move, we know
- // that the captured piece cannot be a pawn.
- assert(st->capture != PAWN);
- npMaterial[them] += piece_value_midgame(st->capture);
-
// Update piece list
pieceList[them][st->capture][pieceCount[them][st->capture]] = to;
index[to] = pieceCount[them][st->capture];
assert(piece_on(from) == EMPTY);
assert(piece_on(capsq) == EMPTY);
- // Replace captured piece
+ // Restore captured pawn
set_bit(&(byColorBB[them]), capsq);
set_bit(&(byTypeBB[PAWN]), capsq);
set_bit(&(byTypeBB[0]), capsq);
board[capsq] = piece_of_color_and_type(them, PAWN);
- // Remove moving piece from destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[PAWN]), to);
- clear_bit(&(byTypeBB[0]), to);
+ // Move capturing pawn back to source square
+ Bitboard move_bb = make_move_bb(to, from);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[PAWN]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb);
board[to] = EMPTY;
-
- // Replace moving piece at source square
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[PAWN]), from);
- set_bit(&(byTypeBB[0]), from);
board[from] = piece_of_color_and_type(us, PAWN);
- // Update piece list:
+ // Update piece list
pieceList[us][PAWN][index[to]] = from;
index[from] = index[to];
pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq;
index[capsq] = pieceCount[them][PAWN];
- // Update piece count:
+ // Update piece count
pieceCount[them][PAWN]++;
}
assert(!is_check());
// Back up the information necessary to undo the null move to the supplied
- // StateInfo 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.
+ // 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.lastMove = st->lastMove;
backupSt.epSquare = st->epSquare;
+ backupSt.key = st->key;
+ backupSt.mgValue = st->mgValue;
+ backupSt.egValue = st->egValue;
backupSt.previous = st->previous;
st->previous = &backupSt;
assert(!is_check());
// Restore information from the our backup StateInfo object
- st->lastMove = st->previous->lastMove;
st->epSquare = st->previous->epSquare;
+ st->key = st->previous->key;
+ st->mgValue = st->previous->mgValue;
+ st->egValue = st->previous->egValue;
st->previous = st->previous->previous;
- if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[st->epSquare];
-
// Update the necessary information
sideToMove = opposite_color(sideToMove);
st->rule50--;
gamePly--;
- st->key ^= zobSideToMove;
-
- st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
assert(is_ok());
}
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 {
// Material values
0, 0
};
- Bitboard attackers, occ, b;
+ Bitboard attackers, stmAttackers, occ, b;
assert(square_is_ok(from) || from == SQ_NONE);
assert(square_is_ok(to));
Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S);
capture = piece_on(capQq);
-
assert(type_of_piece_on(capQq) == PAWN);
// Remove the captured pawn
}
// If the opponent has no attackers we are finished
- if ((attackers & pieces_of_color(them)) == EmptyBoardBB)
+ stmAttackers = attackers & pieces_of_color(them);
+ if (!stmAttackers)
return seeValues[capture];
attackers &= occ; // Remove the moving piece
// Locate the least valuable attacker for the side to move. The loop
// below looks like it is potentially infinite, but it isn't. We know
// that the side to move still has at least one attacker left.
- for (pt = PAWN; !(attackers & pieces_of_color_and_type(c, pt)); pt++)
+ for (pt = PAWN; !(stmAttackers & pieces_of_type(pt)); pt++)
assert(pt < KING);
// Remove the attacker we just found from the 'attackers' bitboard,
// and scan for new X-ray attacks behind the attacker.
- b = attackers & pieces_of_color_and_type(c, pt);
- occ ^= (b & -b);
+ b = stmAttackers & pieces_of_type(pt);
+ occ ^= (b & (~b + 1));
attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens())
| (bishop_attacks_bb(to, occ) & bishops_and_queens());
// before beginning the next iteration
lastCapturingPieceValue = seeValues[pt];
c = opposite_color(c);
+ stmAttackers = attackers & pieces_of_color(c);
// Stop after a king capture
- if (pt == KING && (attackers & pieces_of_color(c)))
+ if (pt == KING && stmAttackers)
{
assert(n < 32);
- swapList[n++] = 100;
+ swapList[n++] = QueenValueMidgame*10;
break;
}
- } while (attackers & pieces_of_color(c));
+ } while (stmAttackers);
// Having built the swap list, we negamax through it to find the best
// achievable score from the point of view of the side to move
}
-/// Position::setStartState() copies the content of the argument
+/// Position::saveState() copies the content of the current state
/// inside startState and makes st point to it. This is needed
/// when the st pointee could become stale, as example because
/// the caller is about to going out of scope.
-void Position::setStartState(const StateInfo& s) {
+void Position::saveState() {
- startState = s;
+ startState = *st;
st = &startState;
+ st->previous = NULL; // as a safe guard
}
Value Position::compute_non_pawn_material(Color c) const {
Value result = Value(0);
- Square s;
for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
{
Bitboard b = pieces_of_color_and_type(c, pt);
- while(b)
+ while (b)
{
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
+ assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt));
+ pop_1st_bit(&b);
result += piece_value_midgame(pt);
}
}
}
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated. Note that this function is currently very
-/// slow, and shouldn't be used frequently inside the search.
-
-bool Position::is_mate() const {
-
- if (is_check())
- {
- MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0));
- return mp.get_next_move() == MOVE_NONE;
- }
- return false;
-}
-
-
/// Position::is_draw() tests whether the position is drawn by material,
/// repetition, or the 50 moves rule. It does not detect stalemates, this
/// must be done by the search.
}
+/// Position::is_mate() returns true or false depending on whether the
+/// side to move is checkmated.
+
+bool Position::is_mate() const {
+
+ MoveStack moves[256];
+
+ return is_check() && !generate_evasions(*this, moves, pinned_pieces(sideToMove));
+}
+
+
/// Position::has_mate_threat() tests whether a given color has a mate in one
-/// from the current position. This function is quite slow, but it doesn't
-/// matter, because it is currently only called from PV nodes, which are rare.
+/// from the current position.
bool Position::has_mate_threat(Color c) {
StateInfo st1, st2;
Color stm = side_to_move();
- // The following lines are useless and silly, but prevents gcc from
- // emitting a stupid warning stating that u1.lastMove and u1.epSquare might
- // be used uninitialized.
- st1.lastMove = st->lastMove;
- st1.epSquare = st->epSquare;
-
if (is_check())
return false;
MoveStack mlist[120];
int count;
bool result = false;
+ Bitboard dc = discovered_check_candidates(sideToMove);
+ Bitboard pinned = pinned_pieces(sideToMove);
- // Generate legal moves
- count = generate_legal_moves(*this, mlist);
+ // Generate pseudo-legal non-capture and capture check moves
+ count = generate_non_capture_checks(*this, mlist, dc);
+ count += generate_captures(*this, mlist + count);
// Loop through the moves, and see if one of them is mate
for (int i = 0; i < count; i++)
{
- do_move(mlist[i].move, st2);
+ Move move = mlist[i].move;
+
+ if (!pl_move_is_legal(move, pinned))
+ continue;
+
+ do_move(move, st2);
if (is_mate())
result = true;
- undo_move(mlist[i].move);
+ undo_move(move);
}
// Undo null move, if necessary
/// 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());
st->egValue = compute_value<EndGame>();
// Material
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
+ st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
assert(is_ok());
}
if (failedStep) (*failedStep)++;
if (debugNonPawnMaterial)
{
- if (npMaterial[WHITE] != compute_non_pawn_material(WHITE))
+ if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
return false;
- if (npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
return false;
}