/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
// Table used to drive the defending king towards the edge of the board
// in KX vs K and KQ vs KR endgames.
- const int MateTable[64] = {
+ const int MateTable[SQUARE_NB] = {
100, 90, 80, 70, 70, 80, 90, 100,
90, 70, 60, 50, 50, 60, 70, 90,
80, 60, 40, 30, 30, 40, 60, 80,
// Table used to drive the defending king towards a corner square of the
// right color in KBN vs K endgames.
- const int KBNKMateTable[64] = {
+ const int KBNKMateTable[SQUARE_NB] = {
200, 190, 180, 170, 160, 150, 140, 130,
190, 180, 170, 160, 150, 140, 130, 140,
180, 170, 155, 140, 140, 125, 140, 150,
add<KRKP>("KRKP");
add<KRKB>("KRKB");
add<KRKN>("KRKN");
+ add<KQKP>("KQKP");
add<KQKR>("KQKR");
add<KBBKN>("KBBKN");
add<KNPK>("KNPK");
+ add<KNPKB>("KNPKB");
add<KRPKR>("KRPKR");
add<KBPKB>("KBPKB");
add<KBPKN>("KBPKN");
// Stalemate detection with lone king
if ( pos.side_to_move() == weakerSide
- && !pos.in_check()
+ && !pos.checkers()
&& !MoveList<LEGAL>(pos).size()) {
return VALUE_DRAW;
}
Square loserKSq = pos.king_square(weakerSide);
Value result = pos.non_pawn_material(strongerSide)
- + pos.piece_count(strongerSide, PAWN) * PawnValueEndgame
+ + pos.piece_count(strongerSide, PAWN) * PawnValueEg
+ MateTable[loserKSq]
+ DistanceBonus[square_distance(winnerKSq, loserKSq)];
assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO);
- assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame + BishopValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == KnightValueMg + BishopValueMg);
assert(pos.piece_count(strongerSide, BISHOP) == 1);
assert(pos.piece_count(strongerSide, KNIGHT) == 1);
assert(pos.piece_count(strongerSide, PAWN) == 0);
Square winnerKSq = pos.king_square(strongerSide);
Square loserKSq = pos.king_square(weakerSide);
- Square bishopSquare = pos.piece_list(strongerSide, BISHOP)[0];
+ Square bishopSq = pos.piece_list(strongerSide, BISHOP)[0];
// kbnk_mate_table() tries to drive toward corners A1 or H8,
// if we have a bishop that cannot reach the above squares we
// mirror the kings so to drive enemy toward corners A8 or H1.
- if (opposite_colors(bishopSquare, SQ_A1))
+ if (opposite_colors(bishopSq, SQ_A1))
{
winnerKSq = mirror(winnerKSq);
loserKSq = mirror(loserKSq);
assert(pos.piece_count(weakerSide, PAWN) == 0);
Square wksq, bksq, wpsq;
- Color stm;
+ Color us;
if (strongerSide == WHITE)
{
wksq = pos.king_square(WHITE);
bksq = pos.king_square(BLACK);
wpsq = pos.piece_list(WHITE, PAWN)[0];
- stm = pos.side_to_move();
+ us = pos.side_to_move();
}
else
{
wksq = ~pos.king_square(BLACK);
bksq = ~pos.king_square(WHITE);
wpsq = ~pos.piece_list(BLACK, PAWN)[0];
- stm = ~pos.side_to_move();
+ us = ~pos.side_to_move();
}
if (file_of(wpsq) >= FILE_E)
wpsq = mirror(wpsq);
}
- if (!Bitbases::probe_kpk(wksq, wpsq, bksq, stm))
+ if (!Bitbases::probe_kpk(wksq, wpsq, bksq, us))
return VALUE_DRAW;
- Value result = VALUE_KNOWN_WIN
- + PawnValueEndgame
- + Value(rank_of(wpsq));
+ Value result = VALUE_KNOWN_WIN + PawnValueEg + Value(rank_of(wpsq));
return strongerSide == pos.side_to_move() ? result : -result;
}
template<>
Value Endgame<KRKP>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == RookValueMg);
assert(pos.piece_count(strongerSide, PAWN) == 0);
assert(pos.non_pawn_material(weakerSide) == 0);
assert(pos.piece_count(weakerSide, PAWN) == 1);
// If the stronger side's king is in front of the pawn, it's a win
if (wksq < bpsq && file_of(wksq) == file_of(bpsq))
- result = RookValueEndgame - Value(square_distance(wksq, bpsq));
+ result = RookValueEg - Value(square_distance(wksq, bpsq));
// If the weaker side's king is too far from the pawn and the rook,
// it's a win
else if ( square_distance(bksq, bpsq) - (tempo ^ 1) >= 3
&& square_distance(bksq, wrsq) >= 3)
- result = RookValueEndgame - Value(square_distance(wksq, bpsq));
+ result = RookValueEg - Value(square_distance(wksq, bpsq));
// If the pawn is far advanced and supported by the defending king,
// the position is drawish
template<>
Value Endgame<KRKB>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == RookValueMg);
assert(pos.piece_count(strongerSide, PAWN) == 0);
- assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == BishopValueMg);
assert(pos.piece_count(weakerSide, PAWN) == 0);
assert(pos.piece_count(weakerSide, BISHOP) == 1);
template<>
Value Endgame<KRKN>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == RookValueMg);
assert(pos.piece_count(strongerSide, PAWN) == 0);
- assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == KnightValueMg);
assert(pos.piece_count(weakerSide, PAWN) == 0);
assert(pos.piece_count(weakerSide, KNIGHT) == 1);
}
+/// KQ vs KP. In general, a win for the stronger side, however, there are a few
+/// important exceptions. Pawn on 7th rank, A,C,F or H file, with king next can
+/// be a draw, so we scale down to distance between kings only.
+template<>
+Value Endgame<KQKP>::operator()(const Position& pos) const {
+
+ assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
+ assert(pos.piece_count(strongerSide, PAWN) == 0);
+ assert(pos.non_pawn_material(weakerSide) == 0);
+ assert(pos.piece_count(weakerSide, PAWN) == 1);
+
+ Square winnerKSq = pos.king_square(strongerSide);
+ Square loserKSq = pos.king_square(weakerSide);
+ Square pawnSq = pos.piece_list(weakerSide, PAWN)[0];
+
+ Value result = QueenValueEg
+ - PawnValueEg
+ + DistanceBonus[square_distance(winnerKSq, loserKSq)];
+
+ if ( square_distance(loserKSq, pawnSq) == 1
+ && relative_rank(weakerSide, pawnSq) == RANK_7)
+ {
+ File f = file_of(pawnSq);
+
+ if (f == FILE_A || f == FILE_C || f == FILE_F || f == FILE_H)
+ result = Value(DistanceBonus[square_distance(winnerKSq, loserKSq)]);
+ }
+ return strongerSide == pos.side_to_move() ? result : -result;
+}
+
+
/// KQ vs KR. This is almost identical to KX vs K: We give the attacking
/// king a bonus for having the kings close together, and for forcing the
/// defending king towards the edge. If we also take care to avoid null move
template<>
Value Endgame<KQKR>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
assert(pos.piece_count(strongerSide, PAWN) == 0);
- assert(pos.non_pawn_material(weakerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == RookValueMg);
assert(pos.piece_count(weakerSide, PAWN) == 0);
Square winnerKSq = pos.king_square(strongerSide);
Square loserKSq = pos.king_square(weakerSide);
- Value result = QueenValueEndgame
- - RookValueEndgame
+ Value result = QueenValueEg
+ - RookValueEg
+ MateTable[loserKSq]
+ DistanceBonus[square_distance(winnerKSq, loserKSq)];
Value Endgame<KBBKN>::operator()(const Position& pos) const {
assert(pos.piece_count(strongerSide, BISHOP) == 2);
- assert(pos.non_pawn_material(strongerSide) == 2*BishopValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == 2*BishopValueMg);
assert(pos.piece_count(weakerSide, KNIGHT) == 1);
- assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == KnightValueMg);
assert(!pos.pieces(PAWN));
- Value result = BishopValueEndgame;
+ Value result = BishopValueEg;
Square wksq = pos.king_square(strongerSide);
Square bksq = pos.king_square(weakerSide);
Square nsq = pos.piece_list(weakerSide, KNIGHT)[0];
template<>
ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
assert(pos.piece_count(strongerSide, BISHOP) == 1);
assert(pos.piece_count(strongerSide, PAWN) >= 1);
return SCALE_FACTOR_DRAW;
}
}
+
+ // All pawns on same B or G file? Then potential draw
+ if ( (pawnFile == FILE_B || pawnFile == FILE_G)
+ && !(pos.pieces(PAWN) & ~file_bb(pawnFile))
+ && pos.non_pawn_material(weakerSide) == 0
+ && pos.piece_count(weakerSide, PAWN) >= 1)
+ {
+ // Get weaker pawn closest to opponent's queening square
+ Bitboard wkPawns = pos.pieces(weakerSide, PAWN);
+ Square weakerPawnSq = strongerSide == WHITE ? msb(wkPawns) : lsb(wkPawns);
+
+ Square strongerKingSq = pos.king_square(strongerSide);
+ Square weakerKingSq = pos.king_square(weakerSide);
+ Square bishopSq = pos.piece_list(strongerSide, BISHOP)[0];
+
+ // Draw if weaker pawn is on rank 7, bishop can't attack the pawn, and
+ // weaker king can stop opposing opponent's king from penetrating.
+ if ( relative_rank(strongerSide, weakerPawnSq) == RANK_7
+ && opposite_colors(bishopSq, weakerPawnSq)
+ && square_distance(weakerPawnSq, weakerKingSq) <= square_distance(weakerPawnSq, strongerKingSq))
+ return SCALE_FACTOR_DRAW;
+ }
+
return SCALE_FACTOR_NONE;
}
template<>
ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
assert(pos.piece_count(strongerSide, QUEEN) == 1);
assert(pos.piece_count(strongerSide, PAWN) == 0);
assert(pos.piece_count(weakerSide, ROOK) == 1);
template<>
ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == RookValueMg);
assert(pos.piece_count(strongerSide, PAWN) == 1);
- assert(pos.non_pawn_material(weakerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == RookValueMg);
assert(pos.piece_count(weakerSide, PAWN) == 0);
Square wksq = pos.king_square(strongerSide);
template<>
ScaleFactor Endgame<KRPPKRP>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == RookValueMg);
assert(pos.piece_count(strongerSide, PAWN) == 2);
- assert(pos.non_pawn_material(weakerSide) == RookValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == RookValueMg);
assert(pos.piece_count(weakerSide, PAWN) == 1);
Square wpsq1 = pos.piece_list(strongerSide, PAWN)[0];
// Does the defending king block the pawns?
if ( square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1
|| ( file_of(ksq) == FILE_A
- && !in_front_bb(strongerSide, ksq) & pawns))
+ && !(in_front_bb(strongerSide, ksq) & pawns)))
return SCALE_FACTOR_DRAW;
}
// Are all pawns on the 'h' file?
// Does the defending king block the pawns?
if ( square_distance(ksq, relative_square(strongerSide, SQ_H8)) <= 1
|| ( file_of(ksq) == FILE_H
- && !in_front_bb(strongerSide, ksq) & pawns))
+ && !(in_front_bb(strongerSide, ksq) & pawns)))
return SCALE_FACTOR_DRAW;
}
return SCALE_FACTOR_NONE;
template<>
ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
assert(pos.piece_count(strongerSide, BISHOP) == 1);
assert(pos.piece_count(strongerSide, PAWN) == 1);
- assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == BishopValueMg);
assert(pos.piece_count(weakerSide, BISHOP) == 1);
assert(pos.piece_count(weakerSide, PAWN) == 0);
template<>
ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
assert(pos.piece_count(strongerSide, BISHOP) == 1);
assert(pos.piece_count(strongerSide, PAWN) == 2);
- assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == BishopValueMg);
assert(pos.piece_count(weakerSide, BISHOP) == 1);
assert(pos.piece_count(weakerSide, PAWN) == 0);
template<>
ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
assert(pos.piece_count(strongerSide, BISHOP) == 1);
assert(pos.piece_count(strongerSide, PAWN) == 1);
- assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame);
+ assert(pos.non_pawn_material(weakerSide) == KnightValueMg);
assert(pos.piece_count(weakerSide, KNIGHT) == 1);
assert(pos.piece_count(weakerSide, PAWN) == 0);
template<>
ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame);
+ assert(pos.non_pawn_material(strongerSide) == KnightValueMg);
assert(pos.piece_count(strongerSide, KNIGHT) == 1);
assert(pos.piece_count(strongerSide, PAWN) == 1);
assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
}
+/// K, knight and a pawn vs K and bishop. If knight can block bishop from taking
+/// pawn, it's a win. Otherwise, drawn.
+template<>
+ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
+
+ Square pawnSq = pos.piece_list(strongerSide, PAWN)[0];
+ Square bishopSq = pos.piece_list(weakerSide, BISHOP)[0];
+ Square weakerKingSq = pos.king_square(weakerSide);
+
+ // King needs to get close to promoting pawn to prevent knight from blocking.
+ // Rules for this are very tricky, so just approximate.
+ if (forward_bb(strongerSide, pawnSq) & pos.attacks_from<BISHOP>(bishopSq))
+ return ScaleFactor(square_distance(weakerKingSq, pawnSq));
+
+ return SCALE_FACTOR_NONE;
+}
+
+
/// K and a pawn vs K and a pawn. This is done by removing the weakest side's
/// pawn and probing the KP vs K bitbase: If the weakest side has a draw without
/// the pawn, she probably has at least a draw with the pawn as well. The exception
Square wksq = pos.king_square(strongerSide);
Square bksq = pos.king_square(weakerSide);
Square wpsq = pos.piece_list(strongerSide, PAWN)[0];
- Color stm = pos.side_to_move();
+ Color us = pos.side_to_move();
if (strongerSide == BLACK)
{
wksq = ~wksq;
bksq = ~bksq;
wpsq = ~wpsq;
- stm = ~stm;
+ us = ~us;
}
if (file_of(wpsq) >= FILE_E)
// Probe the KPK bitbase with the weakest side's pawn removed. If it's a draw,
// it's probably at least a draw even with the pawn.
- return Bitbases::probe_kpk(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
+ return Bitbases::probe_kpk(wksq, wpsq, bksq, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
}
projects / stockfish / blobdiff