/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
}
-/// Position:hidden_checkers() returns a bitboard of all pinned / discovered check
-/// pieces, according to the call parameters. Pinned pieces protect our king and
-/// discovered check pieces attack the enemy king.
+/// Position::check_blockers() returns a bitboard of all the pieces with color
+/// 'c' that are blocking check on the king with color 'kingColor'. A piece
+/// blocks a check if removing that piece from the board would result in a
+/// position where the king is in check. A check blocking piece can be either a
+/// pinned or a discovered check piece, according if its color 'c' is the same
+/// or the opposite of 'kingColor'.
-Bitboard Position::hidden_checkers(Color c, Color kingColor) const {
+Bitboard Position::check_blockers(Color c, Color kingColor) const {
Bitboard b, pinners, result = 0;
Square ksq = king_square(kingColor);
}
-/// Position::move_gives_check() tests whether a pseudo-legal move gives a check
+/// Position::gives_check() tests whether a pseudo-legal move gives a check
bool Position::gives_check(Move m, const CheckInfo& ci) const {
// Is there a discovered check?
if ( unlikely(ci.dcCandidates)
&& (ci.dcCandidates & from)
- && !aligned(from, to, king_square(~sideToMove)))
+ && !aligned(from, to, ci.ksq))
return true;
// Can we skip the ugly special cases?
if (type_of(m) == NORMAL)
return false;
- Color us = sideToMove;
- Square ksq = king_square(~us);
-
switch (type_of(m))
{
case PROMOTION:
- return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ksq;
+ return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq;
// En passant capture with check? We have already handled the case
// of direct checks and ordinary discovered check, so the only case we
Square capsq = file_of(to) | rank_of(from);
Bitboard b = (pieces() ^ from ^ capsq) | to;
- return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK))
- | (attacks_bb<BISHOP>(ksq, b) & pieces(us, QUEEN, BISHOP));
+ return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP));
}
case CASTLING:
{
Square kfrom = from;
Square rfrom = to; // Castling is encoded as 'King captures the rook'
- Square kto = relative_square(us, rfrom > kfrom ? SQ_G1 : SQ_C1);
- Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1);
+ Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1);
- return (PseudoAttacks[ROOK][rto] & ksq)
- && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ksq);
+ return (PseudoAttacks[ROOK][rto] & ci.ksq)
+ && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq);
}
default:
assert(false);
// Add the new entry to the swap list
swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
- ++slIndex;
// Locate and remove the next least valuable attacker
captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
- stm = ~stm;
- stmAttackers = attackers & pieces(stm);
// Stop before processing a king capture
- if (captured == KING && stmAttackers)
+ if (captured == KING)
{
- swapList[slIndex++] = QueenValueMg * 16;
+ if (stmAttackers == attackers)
+ ++slIndex;
+
break;
}
+ stm = ~stm;
+ stmAttackers = attackers & pieces(stm);
+ ++slIndex;
+
} while (stmAttackers);
// Having built the swap list, we negamax through it to find the best