/*
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
S( 25, 41), S( 25, 41), S(25, 41), S(25, 41) }
};
- // Outpost[PieceType][Square] contains bonuses of knights and bishops, indexed
- // by piece type and square (from white's point of view).
+ // Outpost[PieceType][Square] contains bonuses for knights and bishops outposts,
+ // indexed by piece type and square (from white's point of view).
const Value Outpost[][SQUARE_NB] = {
{
// A B C D E F G H
// Threat[attacking][attacked] contains bonuses according to which piece
// type attacks which one.
const Score Threat[][PIECE_TYPE_NB] = {
- {}, {},
- { S(0, 0), S( 7, 39), S( 0, 0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT
- { S(0, 0), S( 7, 39), S(24, 49), S( 0, 0), S(41,100), S(41,100) }, // BISHOP
- { S(0, 0), S( 0, 22), S(15, 49), S(15, 49), S( 0, 0), S(24, 49) }, // ROOK
- { S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0, 0) } // QUEEN
+ { S(0, 0), S( 7, 39), S(24, 49), S(24, 49), S(41,100), S(41,100) }, // Minor
+ { S(0, 0), S(15, 39), S(15, 45), S(15, 45), S(15, 45), S(24, 49) }, // Major
};
// ThreatenedByPawn[PieceType] contains a penalty according to which piece
#undef S
const Score Tempo = make_score(24, 11);
- const Score BishopPin = make_score(66, 11);
const Score RookOn7th = make_score(11, 20);
const Score QueenOn7th = make_score( 3, 8);
const Score RookOnPawn = make_score(10, 28);
// happen in Chess960 games.
const Score TrappedBishopA1H1 = make_score(50, 50);
- // The SpaceMask[Color] contains the area of the board which is considered
- // by the space evaluation. In the middle game, each side is given a bonus
+ // SpaceMask[Color] contains the area of the board which is considered
+ // by the space evaluation. In the middlegame, each side is given a bonus
// based on how many squares inside this area are safe and available for
// friendly minor pieces.
const Bitboard SpaceMask[] = {
};
// King danger constants and variables. The king danger scores are taken
- // from the KingDanger[]. Various little "meta-bonuses" measuring
- // the strength of the enemy attack are added up into an integer, which
- // is used as an index to KingDanger[].
+ // from KingDanger[]. Various little "meta-bonuses" measuring the strength
+ // of the enemy attack are added up into an integer, which is used as an
+ // index to KingDanger[].
//
// KingAttackWeights[PieceType] contains king attack weights by piece type
const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
const int BishopCheck = 2;
const int KnightCheck = 3;
- // KingExposed[Square] contains penalties based on the position of the
- // defending king, indexed by king's square (from white's point of view).
- const int KingExposed[] = {
- 2, 0, 2, 5, 5, 2, 0, 2,
- 2, 2, 4, 8, 8, 4, 2, 2,
- 7, 10, 12, 12, 12, 12, 10, 7,
- 15, 15, 15, 15, 15, 15, 15, 15,
- 15, 15, 15, 15, 15, 15, 15, 15,
- 15, 15, 15, 15, 15, 15, 15, 15,
- 15, 15, 15, 15, 15, 15, 15, 15,
- 15, 15, 15, 15, 15, 15, 15, 15
- };
-
// KingDanger[Color][attackUnits] contains the actual king danger weighted
// scores, indexed by color and by a calculated integer number.
Score KingDanger[COLOR_NB][128];
namespace Eval {
/// evaluate() is the main evaluation function. It always computes two
- /// values, an endgame score and a middle game score, and interpolates
+ /// values, an endgame score and a middlegame score, and interpolates
/// between them based on the remaining material.
Value evaluate(const Position& pos) {
score += evaluate_unstoppable_pawns(pos, WHITE, ei)
- evaluate_unstoppable_pawns(pos, BLACK, ei);
- // Evaluate space for both sides, only in middle-game.
+ // Evaluate space for both sides, only in middlegame
if (ei.mi->space_weight())
{
int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
score += apply_weight(s * ei.mi->space_weight(), Weights[Space]);
}
- // Scale winning side if position is more drawish that what it appears
+ // Scale winning side if position is more drawish than it appears
ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
: ei.mi->scale_factor(pos, BLACK);
&& sf == SCALE_FACTOR_NORMAL)
{
// Ignoring any pawns, do both sides only have a single bishop and no
- // other pieces ?
+ // other pieces?
if ( pos.non_pawn_material(WHITE) == BishopValueMg
&& pos.non_pawn_material(BLACK) == BishopValueMg)
{
{
ei.kingRing[Them] = b | shift_bb<Down>(b);
b &= ei.attackedBy[Us][PAWN];
- ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
+ ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) : 0;
ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
}
else
}
- // evaluate_outposts() evaluates bishop and knight outposts squares
+ // evaluate_outposts() evaluates bishop and knight outpost squares
template<PieceType Piece, Color Us>
Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
Value bonus = Outpost[Piece == BISHOP][relative_square(Us, s)];
// Increase bonus if supported by pawn, especially if the opponent has
- // no minor piece which can exchange the outpost piece.
+ // no minor piece which can trade with the outpost piece.
if (bonus && (ei.attackedBy[Us][PAWN] & s))
{
if ( !pos.pieces(Them, KNIGHT)
if (ei.attackedBy[Them][PAWN] & s)
score -= ThreatenedByPawn[Piece];
- // Otherwise give a bonus if we are a bishop and can pin a piece or can
- // give a discovered check through an x-ray attack.
- else if ( Piece == BISHOP
- && (PseudoAttacks[Piece][pos.king_square(Them)] & s)
- && !more_than_one(BetweenBB[s][pos.king_square(Them)] & pos.pieces()))
- score += BishopPin;
-
// Penalty for bishop with same coloured pawns
if (Piece == BISHOP)
score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
Score score = ei.pi->king_safety<Us>(pos, ksq);
// Main king safety evaluation
- if ( ei.kingAttackersCount[Them] >= 2
- && ei.kingAdjacentZoneAttacksCount[Them])
+ if (ei.kingAttackersCount[Them])
{
// Find the attacked squares around the king which have no defenders
// apart from the king itself
// Initialize the 'attackUnits' variable, which is used later on as an
// index to the KingDanger[] array. The initial value is based on the
// number and types of the enemy's attacking pieces, the number of
- // attacked and undefended squares around our king, the square of the
- // king, and the quality of the pawn shelter.
+ // attacked and undefended squares around our king and the quality of
+ // the pawn shelter (current 'score' value).
attackUnits = std::min(20, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
+ 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
- + KingExposed[relative_square(Us, ksq)]
- mg_value(score) / 32;
// Analyse the enemy's safe queen contact checks. Firstly, find the
& ~ei.attackedBy[Them][PAWN]
& ei.attackedBy[Us][ALL_PIECES];
- // Add bonus according to type of attacked enemy piece and to the
- // type of attacking piece, from knights to queens. Kings are not
- // considered because are already handled in king evaluation.
+ // Add a bonus according if the attacking pieces are minor or major
if (weakEnemies)
- for (PieceType pt1 = KNIGHT; pt1 < KING; ++pt1)
- {
- b = ei.attackedBy[Us][pt1] & weakEnemies;
- if (b)
- for (PieceType pt2 = PAWN; pt2 < KING; ++pt2)
- if (b & pos.pieces(pt2))
- score += Threat[pt1][pt2];
- }
+ {
+ b = weakEnemies & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+ if (b)
+ score += Threat[0][type_of(pos.piece_on(lsb(b)))];
+
+ b = weakEnemies & (ei.attackedBy[Us][ROOK] | ei.attackedBy[Us][QUEEN]);
+ if (b)
+ score += Threat[1][type_of(pos.piece_on(lsb(b)))];
+ }
if (Trace)
Tracing::scores[Us][THREAT] = score;
if (Trace)
Tracing::scores[Us][PASSED] = apply_weight(score, Weights[PassedPawns]);
- // Add the scores to the middle game and endgame eval
+ // Add the scores to the middlegame and endgame eval
return apply_weight(score, Weights[PassedPawns]);
}
}
- // interpolate() interpolates between a middle game and an endgame score,
+ // interpolate() interpolates between a middlegame and an endgame score,
// based on game phase. It also scales the return value by a ScaleFactor array.
Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {
projects / stockfish / blobdiff