/*
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
namespace {
- enum ExtendedPieceType { // Used for tracing
- PST = 8, IMBALANCE, MOBILITY, THREAT, PASSED, UNSTOPPABLE, SPACE, TOTAL
- };
-
- namespace Tracing {
-
- Score scores[COLOR_NB][TOTAL + 1];
- std::stringstream stream;
-
- void add(int idx, Score term_w, Score term_b = SCORE_ZERO);
- void row(const char* name, int idx);
- std::string do_trace(const Position& pos);
- }
-
// Struct EvalInfo contains various information computed and collected
// by the evaluation functions.
struct EvalInfo {
// king is on g8 and there's a white knight on g5, this knight adds
// 2 to kingAdjacentZoneAttacksCount[BLACK].
int kingAdjacentZoneAttacksCount[COLOR_NB];
+
+ Bitboard pinnedPieces[COLOR_NB];
};
- // Evaluation grain size, must be a power of 2
- const int GrainSize = 4;
+ namespace Tracing {
+
+ enum Terms { // First 8 entries are for PieceType
+ PST = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERMS_NB
+ };
+
+ Score terms[COLOR_NB][TERMS_NB];
+ EvalInfo ei;
+ ScaleFactor sf;
+
+ double to_cp(Value v);
+ void add_term(int idx, Score term_w, Score term_b = SCORE_ZERO);
+ void format_row(std::stringstream& ss, const char* name, int idx);
+ std::string do_trace(const Position& pos);
+ }
// Evaluation weights, initialized from UCI options
enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
- Score Weights[6];
+ struct Weight { int mg, eg; } Weights[6];
typedef Value V;
#define S(mg, eg) make_score(mg, eg)
//
// Values modified by Joona Kiiski
const Score WeightsInternal[] = {
- S(289, 344), S(233, 201), S(221, 273), S(46, 0), S(271, 0), S(307, 0)
+ S(289, 344), S(233, 201), S(221, 273), S(46, 0), S(271, 0), S(307, 0)
};
// MobilityBonus[PieceType][attacked] contains bonuses for middle and end
// game, indexed by piece type and number of attacked squares not occupied by
// friendly pieces.
const Score MobilityBonus[][32] = {
- {}, {},
- { S(-35,-30), S(-22,-20), S(-9,-10), S( 3, 0), S(15, 10), S(27, 20), // Knights
- S( 37, 28), S( 42, 31), S(44, 33) },
- { S(-22,-27), S( -8,-13), S( 6, 1), S(20, 15), S(34, 29), S(48, 43), // Bishops
- S( 60, 55), S( 68, 63), S(74, 68), S(77, 72), S(80, 75), S(82, 77),
- S( 84, 79), S( 86, 81), S(87, 82), S(87, 82) },
- { S(-17,-33), S(-11,-16), S(-5, 0), S( 1, 16), S( 7, 32), S(13, 48), // Rooks
- S( 18, 64), S( 22, 80), S(26, 96), S(29,109), S(31,115), S(33,119),
- S( 35,122), S( 36,123), S(37,124), S(38,124) },
- { S(-12,-20), S( -8,-13), S(-5, -7), S(-2, -1), S( 1, 5), S( 4, 11), // Queens
- S( 7, 17), S( 10, 23), S(13, 29), S(16, 34), S(18, 38), S(20, 40),
- S( 22, 41), S( 23, 41), S(24, 41), S(25, 41), S(25, 41), S(25, 41),
- S( 25, 41), S( 25, 41), S(25, 41), S(25, 41), S(25, 41), S(25, 41),
- S( 25, 41), S( 25, 41), S(25, 41), S(25, 41), S(25, 41), S(25, 41),
- S( 25, 41), S( 25, 41) }
+ {}, {},
+ { S(-65,-50), S(-42,-30), S(-9,-10), S( 3, 0), S(15, 10), S(27, 20), // Knights
+ S( 37, 28), S( 42, 31), S(44, 33) },
+ { S(-52,-47), S(-28,-23), S( 6, 1), S(20, 15), S(34, 29), S(48, 43), // Bishops
+ S( 60, 55), S( 68, 63), S(74, 68), S(77, 72), S(80, 75), S(82, 77),
+ S( 84, 79), S( 86, 81) },
+ { S(-47,-53), S(-31,-26), S(-5, 0), S( 1, 16), S( 7, 32), S(13, 48), // Rooks
+ S( 18, 64), S( 22, 80), S(26, 96), S(29,109), S(31,115), S(33,119),
+ S( 35,122), S( 36,123), S(37,124) },
+ { S(-42,-40), S(-28,-23), S(-5, -7), S( 0, 0), S( 6, 10), S(11, 19), // Queens
+ S( 13, 29), S( 18, 38), S(20, 40), S(21, 41), S(22, 41), S(22, 41),
+ S( 22, 41), S( 23, 41), S(24, 41), S(25, 41), S(25, 41), S(25, 41),
+ S( 25, 41), S( 25, 41), S(25, 41), S(25, 41), S(25, 41), S(25, 41),
+ 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
+ {// A B C D E F G H
V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
// 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
S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
};
+ // Hanging[side to move] contains a bonus for each enemy hanging piece
+ const Score Hanging[2] = { S(23, 20) , S(35, 45) };
+
#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);
- const Score QueenOnPawn = make_score( 4, 20);
const Score RookOpenFile = make_score(43, 21);
const Score RookSemiopenFile = make_score(19, 10);
const Score BishopPawns = make_score( 8, 12);
+ const Score MinorBehindPawn = make_score(16, 0);
const Score UndefendedMinor = make_score(25, 10);
const Score TrappedRook = make_score(90, 0);
+ const Score Unstoppable = make_score( 0, 20);
// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
// 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[] = {
- (1ULL << SQ_C2) | (1ULL << SQ_D2) | (1ULL << SQ_E2) | (1ULL << SQ_F2) |
- (1ULL << SQ_C3) | (1ULL << SQ_D3) | (1ULL << SQ_E3) | (1ULL << SQ_F3) |
- (1ULL << SQ_C4) | (1ULL << SQ_D4) | (1ULL << SQ_E4) | (1ULL << SQ_F4),
- (1ULL << SQ_C7) | (1ULL << SQ_D7) | (1ULL << SQ_E7) | (1ULL << SQ_F7) |
- (1ULL << SQ_C6) | (1ULL << SQ_D6) | (1ULL << SQ_E6) | (1ULL << SQ_F6) |
- (1ULL << SQ_C5) | (1ULL << SQ_D5) | (1ULL << SQ_E5) | (1ULL << SQ_F5)
+ (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB),
+ (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB)
};
// 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 };
// Bonuses for enemy's safe checks
- const int QueenContactCheck = 6;
- const int RookContactCheck = 4;
- const int QueenCheck = 3;
- const int RookCheck = 2;
- const int BishopCheck = 1;
- const int KnightCheck = 1;
-
- // 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
- };
+ const int QueenContactCheck = 24;
+ const int RookContactCheck = 16;
+ const int QueenCheck = 12;
+ const int RookCheck = 8;
+ const int BishopCheck = 2;
+ const int KnightCheck = 3;
// KingDanger[Color][attackUnits] contains the actual king danger weighted
// scores, indexed by color and by a calculated integer number.
Score KingDanger[COLOR_NB][128];
- // Function prototypes
- template<bool Trace>
- Value do_evaluate(const Position& pos, Value& margin);
-
- template<Color Us>
- void init_eval_info(const Position& pos, EvalInfo& ei);
-
- template<Color Us, bool Trace>
- Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility);
-
- template<Color Us, bool Trace>
- Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]);
-
- template<Color Us, bool Trace>
- Score evaluate_threats(const Position& pos, EvalInfo& ei);
-
- template<Color Us, bool Trace>
- Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
-
- template<Color Us>
- int evaluate_space(const Position& pos, EvalInfo& ei);
-
- Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
-
- Value interpolate(const Score& v, Phase ph, ScaleFactor sf);
- Score apply_weight(Score v, Score w);
- Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
- double to_cp(Value v);
-}
-
-
-namespace Eval {
-
- /// evaluate() is the main evaluation function. It always computes two
- /// values, an endgame score and a middle game score, and interpolates
- /// between them based on the remaining material.
- Value evaluate(const Position& pos, Value& margin) {
- return do_evaluate<false>(pos, margin);
+ // apply_weight() weighs score 'v' by weight 'w' trying to prevent overflow
+ Score apply_weight(Score v, const Weight& w) {
+ return make_score(mg_value(v) * w.mg / 256, eg_value(v) * w.eg / 256);
}
- /// trace() is like evaluate() but instead of a value returns a string suitable
- /// to be print on stdout with the detailed descriptions and values of each
- /// evaluation term. Used mainly for debugging.
- std::string trace(const Position& pos) {
- return Tracing::do_trace(pos);
- }
-
-
- /// init() computes evaluation weights from the corresponding UCI parameters
- /// and setup king tables.
-
- void init() {
-
- Weights[Mobility] = weight_option("Mobility (Midgame)", "Mobility (Endgame)", WeightsInternal[Mobility]);
- Weights[PawnStructure] = weight_option("Pawn Structure (Midgame)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
- Weights[PassedPawns] = weight_option("Passed Pawns (Midgame)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
- Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
- Weights[KingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
- Weights[KingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
-
- const int MaxSlope = 30;
- const int Peak = 1280;
-
- for (int t = 0, i = 1; i < 100; i++)
- {
- t = std::min(Peak, std::min(int(0.4 * i * i), t + MaxSlope));
-
- KingDanger[1][i] = apply_weight(make_score(t, 0), Weights[KingDangerUs]);
- KingDanger[0][i] = apply_weight(make_score(t, 0), Weights[KingDangerThem]);
- }
- }
-
-} // namespace Eval
-
-
-namespace {
-
-template<bool Trace>
-Value do_evaluate(const Position& pos, Value& margin) {
-
- assert(!pos.checkers());
-
- EvalInfo ei;
- Value margins[COLOR_NB];
- Score score, mobilityWhite, mobilityBlack;
- Thread* th = pos.this_thread();
-
- // margins[] store the uncertainty estimation of position's evaluation
- // that typically is used by the search for pruning decisions.
- margins[WHITE] = margins[BLACK] = VALUE_ZERO;
-
- // Initialize score by reading the incrementally updated scores included
- // in the position object (material + piece square tables) and adding
- // Tempo bonus. Score is computed from the point of view of white.
- score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
-
- // Probe the material hash table
- ei.mi = Material::probe(pos, th->materialTable, th->endgames);
- score += ei.mi->material_value();
-
- // If we have a specialized evaluation function for the current material
- // configuration, call it and return.
- if (ei.mi->specialized_eval_exists())
- {
- margin = VALUE_ZERO;
- return ei.mi->evaluate(pos);
- }
-
- // Probe the pawn hash table
- ei.pi = Pawns::probe(pos, th->pawnsTable);
- score += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
-
- // Initialize attack and king safety bitboards
- init_eval_info<WHITE>(pos, ei);
- init_eval_info<BLACK>(pos, ei);
-
- // Evaluate pieces and mobility
- score += evaluate_pieces_of_color<WHITE, Trace>(pos, ei, mobilityWhite)
- - evaluate_pieces_of_color<BLACK, Trace>(pos, ei, mobilityBlack);
-
- score += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
-
- // Evaluate kings after all other pieces because we need complete attack
- // information when computing the king safety evaluation.
- score += evaluate_king<WHITE, Trace>(pos, ei, margins)
- - evaluate_king<BLACK, Trace>(pos, ei, margins);
-
- // Evaluate tactical threats, we need full attack information including king
- score += evaluate_threats<WHITE, Trace>(pos, ei)
- - evaluate_threats<BLACK, Trace>(pos, ei);
-
- // Evaluate passed pawns, we need full attack information including king
- score += evaluate_passed_pawns<WHITE, Trace>(pos, ei)
- - evaluate_passed_pawns<BLACK, Trace>(pos, ei);
-
- // If one side has only a king, check whether exists any unstoppable passed pawn
- if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
- score += evaluate_unstoppable_pawns(pos, ei);
-
- // Evaluate space for both sides, only in middle-game.
- 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
- ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
- : ei.mi->scale_factor(pos, BLACK);
-
- // If we don't already have an unusual scale factor, check for opposite
- // colored bishop endgames, and use a lower scale for those.
- if ( ei.mi->game_phase() < PHASE_MIDGAME
- && pos.opposite_bishops()
- && sf == SCALE_FACTOR_NORMAL)
- {
- // Only the two bishops ?
- if ( pos.non_pawn_material(WHITE) == BishopValueMg
- && pos.non_pawn_material(BLACK) == BishopValueMg)
- {
- // Check for KBP vs KB with only a single pawn that is almost
- // certainly a draw or at least two pawns.
- bool one_pawn = (pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK) == 1);
- sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
- }
- else
- // Endgame with opposite-colored bishops, but also other pieces. Still
- // a bit drawish, but not as drawish as with only the two bishops.
- sf = ScaleFactor(50);
- }
+ // weight_option() computes the value of an evaluation weight, by combining
+ // two UCI-configurable weights (midgame and endgame) with an internal weight.
- margin = margins[pos.side_to_move()];
- Value v = interpolate(score, ei.mi->game_phase(), sf);
+ Weight weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
- // In case of tracing add all single evaluation contributions for both white and black
- if (Trace)
- {
- Tracing::add(PST, pos.psq_score());
- Tracing::add(IMBALANCE, ei.mi->material_value());
- Tracing::add(PAWN, ei.pi->pawns_value());
- Tracing::add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei));
- Score w = ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei);
- Score b = ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei);
- Tracing::add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
- Tracing::add(TOTAL, score);
- Tracing::stream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
- << ", Black: " << to_cp(margins[BLACK])
- << "\nScaling: " << std::noshowpos
- << std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
- << std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
- << std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
- << "Total evaluation: " << to_cp(v);
+ Weight w = { Options[mgOpt] * mg_value(internalWeight) / 100,
+ Options[egOpt] * eg_value(internalWeight) / 100 };
+ return w;
}
- return pos.side_to_move() == WHITE ? v : -v;
-}
-
// init_eval_info() initializes king bitboards for given color adding
// pawn attacks. To be done at the beginning of the evaluation.
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
+ ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
+
Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
- ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
+ ei.attackedBy[Us][ALL_PIECES] = ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
// Init king safety tables only if we are going to use them
if (pos.count<QUEEN>(Us) && pos.non_pawn_material(Us) > QueenValueMg + PawnValueMg)
{
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
+ }
+ else
ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
}
- // evaluate_outposts() evaluates bishop and knight outposts squares
+ // evaluate_outposts() evaluates bishop and knight outpost squares
- template<PieceType Piece, Color Us>
+ template<PieceType Pt, Color Us>
Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
- assert (Piece == BISHOP || Piece == KNIGHT);
+ assert (Pt == BISHOP || Pt == KNIGHT);
// Initial bonus based on square
- Value bonus = Outpost[Piece == BISHOP][relative_square(Us, s)];
+ Value bonus = Outpost[Pt == 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)
else
bonus += bonus / 2;
}
+
return make_score(bonus, bonus);
}
- // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
+ // evaluate_pieces() assigns bonuses and penalties to the pieces of a given color
- template<PieceType Piece, Color Us, bool Trace>
- Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
+ template<PieceType Pt, Color Us, bool Trace>
+ Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility, Bitboard* mobilityArea) {
Bitboard b;
Square s;
Score score = SCORE_ZERO;
+ const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square* pl = pos.list<Piece>(Us);
+ const Square* pl = pos.list<Pt>(Us);
- ei.attackedBy[Us][Piece] = 0;
+ ei.attackedBy[Us][Pt] = 0;
while ((s = *pl++) != SQ_NONE)
{
// Find attacked squares, including x-ray attacks for bishops and rooks
- b = Piece == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN))
- : Piece == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
- : pos.attacks_from<Piece>(s);
+ b = Pt == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN))
+ : Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
+ : pos.attacks_from<Pt>(s);
+
+ if (ei.pinnedPieces[Us] & s)
+ b &= LineBB[pos.king_square(Us)][s];
- ei.attackedBy[Us][Piece] |= b;
+ ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;
if (b & ei.kingRing[Them])
{
ei.kingAttackersCount[Us]++;
- ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
- Bitboard bb = (b & ei.attackedBy[Them][KING]);
+ ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
+ Bitboard bb = b & ei.attackedBy[Them][KING];
if (bb)
ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
}
- int mob = Piece != QUEEN ? popcount<Max15>(b & mobilityArea)
- : popcount<Full >(b & mobilityArea);
+ if (Pt == QUEEN)
+ b &= ~( ei.attackedBy[Them][KNIGHT]
+ | ei.attackedBy[Them][BISHOP]
+ | ei.attackedBy[Them][ROOK]);
+
+ int mob = Pt != QUEEN ? popcount<Max15>(b & mobilityArea[Us])
+ : popcount<Full >(b & mobilityArea[Us]);
- mobility += MobilityBonus[Piece][mob];
+ mobility[Us] += MobilityBonus[Pt][mob];
- // Decrease score if we are attacked by an enemy pawn. Remaining part
+ // Decrease score if we are attacked by an enemy pawn. The remaining part
// of threat evaluation must be done later when we have full attack info.
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 -= ThreatenedByPawn[Pt];
- if (Piece == BISHOP || Piece == KNIGHT)
+ if (Pt == BISHOP || Pt == KNIGHT)
{
+ // Penalty for bishop with same colored pawns
+ if (Pt == BISHOP)
+ score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
+
// Bishop and knight outposts squares
if (!(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
- score += evaluate_outposts<Piece, Us>(pos, ei, s);
+ score += evaluate_outposts<Pt, Us>(pos, ei, s);
- // Pawn in front of knight/bishop
+ // Bishop or knight behind a pawn
if ( relative_rank(Us, s) < RANK_5
&& (pos.pieces(PAWN) & (s + pawn_push(Us))))
- score += make_score(16, 0);
+ score += MinorBehindPawn;
}
- if ( (Piece == ROOK || Piece == QUEEN)
- && relative_rank(Us, s) >= RANK_5)
+ if (Pt == ROOK)
{
- // Major piece on 7th rank and enemy king trapped on 8th
- if ( relative_rank(Us, s) == RANK_7
- && relative_rank(Us, pos.king_square(Them)) == RANK_8)
- score += Piece == ROOK ? RookOn7th : QueenOn7th;
-
- // Major piece attacking enemy pawns on the same rank/file
- Bitboard pawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
- if (pawns)
- score += popcount<Max15>(pawns) * (Piece == ROOK ? RookOnPawn : QueenOnPawn);
- }
+ // Rook piece attacking enemy pawns on the same rank/file
+ if (relative_rank(Us, s) >= RANK_5)
+ {
+ Bitboard pawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
+ if (pawns)
+ score += popcount<Max15>(pawns) * RookOnPawn;
+ }
- // Special extra evaluation for rooks
- if (Piece == ROOK)
- {
// Give a bonus for a rook on a open or semi-open file
- if (ei.pi->semiopen(Us, file_of(s)))
- score += ei.pi->semiopen(Them, file_of(s)) ? RookOpenFile : RookSemiopenFile;
+ if (ei.pi->semiopen_file(Us, file_of(s)))
+ score += ei.pi->semiopen_file(Them, file_of(s)) ? RookOpenFile : RookSemiopenFile;
- if (mob > 3 || ei.pi->semiopen(Us, file_of(s)))
+ if (mob > 3 || ei.pi->semiopen_file(Us, file_of(s)))
continue;
Square ksq = pos.king_square(Us);
- // Penalize rooks which are trapped inside a king. Penalize more if
- // king has lost right to castle.
+ // Penalize rooks which are trapped by a king. Penalize more if the
+ // king has lost its castling capability.
if ( ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
&& (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
- && !ei.pi->semiopen_on_side(Us, file_of(ksq), file_of(ksq) < FILE_E))
- score -= (TrappedRook - make_score(mob * 8, 0)) * (pos.can_castle(Us) ? 1 : 2);
+ && !ei.pi->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
+ score -= (TrappedRook - make_score(mob * 8, 0)) * (1 + !pos.can_castle(Us));
}
// An important Chess960 pattern: A cornered bishop blocked by a friendly
// pawn diagonally in front of it is a very serious problem, especially
// when that pawn is also blocked.
- if ( Piece == BISHOP
+ if ( Pt == BISHOP
&& pos.is_chess960()
&& (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
{
- const enum Piece P = make_piece(Us, PAWN);
Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
- if (pos.piece_on(s + d) == P)
- score -= !pos.is_empty(s + d + pawn_push(Us)) ? TrappedBishopA1H1 * 4
- : pos.piece_on(s + d + d) == P ? TrappedBishopA1H1 * 2
- : TrappedBishopA1H1;
+ if (pos.piece_on(s + d) == make_piece(Us, PAWN))
+ score -= !pos.empty(s + d + pawn_push(Us)) ? TrappedBishopA1H1 * 4
+ : pos.piece_on(s + d + d) == make_piece(Us, PAWN) ? TrappedBishopA1H1 * 2
+ : TrappedBishopA1H1;
}
}
if (Trace)
- Tracing::scores[Us][Piece] = score;
+ Tracing::terms[Us][Pt] = score;
- return score;
+ return score - evaluate_pieces<NextPt, Them, Trace>(pos, ei, mobility, mobilityArea);
}
+ template<>
+ Score evaluate_pieces<KING, WHITE, false>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
+ template<>
+ Score evaluate_pieces<KING, WHITE, true>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
- // evaluate_threats<>() assigns bonuses according to the type of attacking piece
- // and the type of attacked one.
- template<Color Us, bool Trace>
- Score evaluate_threats(const Position& pos, EvalInfo& ei) {
-
- const Color Them = (Us == WHITE ? BLACK : WHITE);
-
- Bitboard b, undefendedMinors, weakEnemies;
- Score score = SCORE_ZERO;
-
- // Undefended minors get penalized even if not under attack
- undefendedMinors = pos.pieces(Them, BISHOP, KNIGHT)
- & ~ei.attackedBy[Them][ALL_PIECES];
-
- if (undefendedMinors)
- score += UndefendedMinor;
-
- // Enemy pieces not defended by a pawn and under our attack
- weakEnemies = pos.pieces(Them)
- & ~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.
- 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];
- }
-
- if (Trace)
- Tracing::scores[Us][THREAT] = score;
-
- return score;
- }
-
-
- // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
- // pieces of a given color.
+ // evaluate_king() assigns bonuses and penalties to a king of a given color
template<Color Us, bool Trace>
- Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
-
- const Color Them = (Us == WHITE ? BLACK : WHITE);
-
- Score score = mobility = SCORE_ZERO;
-
- // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
- const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces(Us, PAWN, KING));
-
- score += evaluate_pieces<KNIGHT, Us, Trace>(pos, ei, mobility, mobilityArea);
- score += evaluate_pieces<BISHOP, Us, Trace>(pos, ei, mobility, mobilityArea);
- score += evaluate_pieces<ROOK, Us, Trace>(pos, ei, mobility, mobilityArea);
- score += evaluate_pieces<QUEEN, Us, Trace>(pos, ei, mobility, mobilityArea);
-
- // Sum up all attacked squares
- ei.attackedBy[Us][ALL_PIECES] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
- | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
- | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
- if (Trace)
- Tracing::scores[Us][MOBILITY] = apply_weight(mobility, Weights[Mobility]);
-
- return score;
- }
-
-
- // evaluate_king<>() assigns bonuses and penalties to a king of a given color
-
- template<Color Us, bool Trace>
- Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) {
+ Score evaluate_king(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
// King shelter and enemy pawns storm
Score score = ei.pi->king_safety<Us>(pos, ksq);
- // King safety. This is quite complicated, and is almost certainly far
- // from optimally tuned.
- if ( ei.kingAttackersCount[Them] >= 2
- && ei.kingAdjacentZoneAttacksCount[Them])
+ // Main king safety evaluation
+ if (ei.kingAttackersCount[Them])
{
- // Find the attacked squares around the king which has no defenders
+ // Find the attacked squares around the king which have no defenders
// apart from the king itself
- undefended = ei.attackedBy[Them][ALL_PIECES] & ei.attackedBy[Us][KING];
- undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
+ undefended = ei.attackedBy[Them][ALL_PIECES]
+ & ei.attackedBy[Us][KING]
+ & ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
| ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
| ei.attackedBy[Us][QUEEN]);
// 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.
- attackUnits = std::min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
+ // 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)]
+ + 2 * (ei.pinnedPieces[Us] != 0)
- mg_value(score) / 32;
- // Analyse enemy's safe queen contact checks. First find undefended
- // squares around the king attacked by enemy queen...
+ // Analyse the enemy's safe queen contact checks. Firstly, find the
+ // undefended squares around the king that are attacked by the enemy's
+ // queen...
b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
if (b)
{
- // ...then remove squares not supported by another enemy piece
+ // ...and then remove squares not supported by another enemy piece
b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
| ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
+
if (b)
attackUnits += QueenContactCheck
* popcount<Max15>(b)
* (Them == pos.side_to_move() ? 2 : 1);
}
- // Analyse enemy's safe rook contact checks. First find undefended
- // squares around the king attacked by enemy rooks...
+ // Analyse the enemy's safe rook contact checks. Firstly, find the
+ // undefended squares around the king that are attacked by the enemy's
+ // rooks...
b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
- // Consider only squares where the enemy rook gives check
+ // Consider only squares where the enemy's rook gives check
b &= PseudoAttacks[ROOK][ksq];
if (b)
{
- // ...then remove squares not supported by another enemy piece
+ // ...and then remove squares not supported by another enemy piece
b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
| ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
+
if (b)
attackUnits += RookContactCheck
* popcount<Max15>(b)
* (Them == pos.side_to_move() ? 2 : 1);
}
- // Analyse enemy's safe distance checks for sliders and knights
+ // Analyse the enemy's safe distance checks for sliders and knights
safe = ~(pos.pieces(Them) | ei.attackedBy[Us][ALL_PIECES]);
b1 = pos.attacks_from<ROOK>(ksq) & safe;
attackUnits = std::min(99, std::max(0, attackUnits));
// Finally, extract the king danger score from the KingDanger[]
- // array and subtract the score from evaluation. Set also margins[]
- // value that will be used for pruning because this value can sometimes
- // be very big, and so capturing a single attacking piece can therefore
- // result in a score change far bigger than the value of the captured piece.
+ // array and subtract the score from evaluation.
score -= KingDanger[Us == Search::RootColor][attackUnits];
- margins[Us] += mg_value(KingDanger[Us == Search::RootColor][attackUnits]);
}
if (Trace)
- Tracing::scores[Us][KING] = score;
+ Tracing::terms[Us][KING] = score;
+
+ return score;
+ }
+
+
+ // evaluate_threats() assigns bonuses according to the type of attacking piece
+ // and the type of attacked one.
+
+ template<Color Us, bool Trace>
+ Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+
+ Bitboard b, undefendedMinors, weakEnemies;
+ Score score = SCORE_ZERO;
+
+ // Undefended minors get penalized even if they are not under attack
+ undefendedMinors = pos.pieces(Them, BISHOP, KNIGHT)
+ & ~ei.attackedBy[Them][ALL_PIECES];
+
+ if (undefendedMinors)
+ score += UndefendedMinor;
+
+ // Enemies not defended by a pawn and under our attack
+ weakEnemies = pos.pieces(Them)
+ & ~ei.attackedBy[Them][PAWN]
+ & ei.attackedBy[Us][ALL_PIECES];
+
+ // Add a bonus according if the attacking pieces are minor or major
+ if (weakEnemies)
+ {
+ b = weakEnemies & (ei.attackedBy[Us][PAWN] | 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)))];
+
+ b = weakEnemies & ~ei.attackedBy[Them][ALL_PIECES];
+ if (b)
+ score += more_than_one(b) ? Hanging[Us != pos.side_to_move()] * popcount<Max15>(b)
+ : Hanging[Us == pos.side_to_move()];
+ }
+
+ if (Trace)
+ Tracing::terms[Us][Tracing::THREAT] = score;
return score;
}
- // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
+ // evaluate_passed_pawns() evaluates the passed pawns of the given color
template<Color Us, bool Trace>
- Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
+ Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
- Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
+ Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
Score score = SCORE_ZERO;
b = ei.pi->passed_pawns(Us);
{
Square s = pop_lsb(&b);
- assert(pos.pawn_is_passed(Us, s));
+ assert(pos.pawn_passed(Us, s));
- int r = int(relative_rank(Us, s) - RANK_2);
+ int r = relative_rank(Us, s) - RANK_2;
int rr = r * (r - 1);
// Base bonus based on rank
- Value mbonus = Value(17 * rr);
- Value ebonus = Value(7 * (rr + r + 1));
+ Value mbonus = Value(17 * rr), ebonus = Value(7 * (rr + r + 1));
if (rr)
{
Square blockSq = s + pawn_push(Us);
- // Adjust bonus based on kings proximity
- ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr);
- ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 2 * rr);
+ // Adjust bonus based on the king's proximity
+ ebonus += square_distance(pos.king_square(Them), blockSq) * 5 * rr
+ - square_distance(pos.king_square(Us ), blockSq) * 2 * rr;
// If blockSq is not the queening square then consider also a second push
- if (rank_of(blockSq) != (Us == WHITE ? RANK_8 : RANK_1))
- ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
+ if (relative_rank(Us, blockSq) != RANK_8)
+ ebonus -= square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr;
- // If the pawn is free to advance, increase bonus
- if (pos.is_empty(blockSq))
+ // If the pawn is free to advance, then increase the bonus
+ if (pos.empty(blockSq))
{
squaresToQueen = forward_bb(Us, s);
- defendedSquares = squaresToQueen & ei.attackedBy[Us][ALL_PIECES];
// If there is an enemy rook or queen attacking the pawn from behind,
// add all X-ray attacks by the rook or queen. Otherwise consider only
else
unsafeSquares = squaresToQueen & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
- // If there aren't enemy attacks huge bonus, a bit smaller if at
- // least block square is not attacked, otherwise smallest bonus.
- int k = !unsafeSquares ? 15 : !(unsafeSquares & blockSq) ? 9 : 3;
+ if ( unlikely(forward_bb(Them, s) & pos.pieces(Us, ROOK, QUEEN))
+ && (forward_bb(Them, s) & pos.pieces(Us, ROOK, QUEEN) & pos.attacks_from<ROOK>(s)))
+ defendedSquares = squaresToQueen;
+ else
+ defendedSquares = squaresToQueen & ei.attackedBy[Us][ALL_PIECES];
+
+ // If there aren't any enemy attacks, assign a big bonus. Otherwise
+ // assign a smaller bonus if the block square isn't attacked.
+ int k = !unsafeSquares ? 15 : !(unsafeSquares & blockSq) ? 9 : 0;
- // Big bonus if the path to queen is fully defended, a bit less
- // if at least block square is defended.
+ // If the path to queen is fully defended, assign a big bonus.
+ // Otherwise assign a smaller bonus if the block square is defended.
if (defendedSquares == squaresToQueen)
k += 6;
else if (defendedSquares & blockSq)
- k += (unsafeSquares & defendedSquares) == unsafeSquares ? 4 : 2;
+ k += 4;
- mbonus += Value(k * rr), ebonus += Value(k * rr);
+ mbonus += k * rr, ebonus += k * rr;
}
} // rr != 0
- // Increase the bonus if the passed pawn is supported by a friendly pawn
- // on the same rank and a bit smaller if it's on the previous rank.
- supportingPawns = pos.pieces(Us, PAWN) & adjacent_files_bb(file_of(s));
- if (supportingPawns & rank_bb(s))
- ebonus += Value(r * 20);
-
- else if (supportingPawns & rank_bb(s - pawn_push(Us)))
- ebonus += Value(r * 12);
-
- // Rook pawns are a special case: They are sometimes worse, and
- // sometimes better than other passed pawns. It is difficult to find
- // good rules for determining whether they are good or bad. For now,
- // we try the following: Increase the value for rook pawns if the
- // other side has no pieces apart from a knight, and decrease the
- // value if the other side has a rook or queen.
- if (file_of(s) == FILE_A || file_of(s) == FILE_H)
- {
- if (pos.non_pawn_material(Them) <= KnightValueMg)
- ebonus += ebonus / 4;
- else if (pos.pieces(Them, ROOK, QUEEN))
- ebonus -= ebonus / 4;
- }
- score += make_score(mbonus, ebonus);
+ if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
+ ebonus += ebonus / 4;
+ score += make_score(mbonus, ebonus);
}
if (Trace)
- Tracing::scores[Us][PASSED] = apply_weight(score, Weights[PassedPawns]);
+ Tracing::terms[Us][Tracing::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]);
}
- // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides, this is quite
- // conservative and returns a winning score only when we are very sure that the pawn is winning.
+ // evaluate_unstoppable_pawns() scores the most advanced among the passed and
+ // candidate pawns. In case opponent has no pieces but pawns, this is somewhat
+ // related to the possibility that pawns are unstoppable.
- Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
+ Score evaluate_unstoppable_pawns(const Position& pos, Color us, const EvalInfo& ei) {
- Bitboard b, b2, blockers, supporters, queeningPath, candidates;
- Square s, blockSq, queeningSquare;
- Color c, winnerSide, loserSide;
- bool pathDefended, opposed;
- int pliesToGo, movesToGo, oppMovesToGo, sacptg, blockersCount, minKingDist, kingptg, d;
- int pliesToQueen[] = { 256, 256 };
+ Bitboard b = ei.pi->passed_pawns(us) | ei.pi->candidate_pawns(us);
- // Step 1. Hunt for unstoppable passed pawns. If we find at least one,
- // record how many plies are required for promotion.
- for (c = WHITE; c <= BLACK; c++)
- {
- // Skip if other side has non-pawn pieces
- if (pos.non_pawn_material(~c))
- continue;
+ if (!b || pos.non_pawn_material(~us))
+ return SCORE_ZERO;
- b = ei.pi->passed_pawns(c);
+ return Unstoppable * int(relative_rank(us, frontmost_sq(us, b)));
+ }
- while (b)
- {
- s = pop_lsb(&b);
- queeningSquare = relative_square(c, file_of(s) | RANK_8);
- queeningPath = forward_bb(c, s);
- // Compute plies to queening and check direct advancement
- movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
- oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
- pathDefended = ((ei.attackedBy[c][ALL_PIECES] & queeningPath) == queeningPath);
+ // evaluate_space() computes the space evaluation for a given side. The
+ // space evaluation is a simple bonus based on the number of safe squares
+ // available for minor pieces on the central four files on ranks 2--4. Safe
+ // squares one, two or three squares behind a friendly pawn are counted
+ // twice. Finally, the space bonus is scaled by a weight taken from the
+ // material hash table. The aim is to improve play on game opening.
+ template<Color Us>
+ int evaluate_space(const Position& pos, const EvalInfo& ei) {
- if (movesToGo >= oppMovesToGo && !pathDefended)
- continue;
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
- // Opponent king cannot block because path is defended and position
- // is not in check. So only friendly pieces can be blockers.
- assert(!pos.checkers());
- assert((queeningPath & pos.pieces()) == (queeningPath & pos.pieces(c)));
+ // Find the safe squares for our pieces inside the area defined by
+ // SpaceMask[]. A square is unsafe if it is attacked by an enemy
+ // pawn, or if it is undefended and attacked by an enemy piece.
+ Bitboard safe = SpaceMask[Us]
+ & ~pos.pieces(Us, PAWN)
+ & ~ei.attackedBy[Them][PAWN]
+ & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
- // Add moves needed to free the path from friendly pieces and retest condition
- movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
+ // Find all squares which are at most three squares behind some friendly pawn
+ Bitboard behind = pos.pieces(Us, PAWN);
+ behind |= (Us == WHITE ? behind >> 8 : behind << 8);
+ behind |= (Us == WHITE ? behind >> 16 : behind << 16);
- if (movesToGo >= oppMovesToGo && !pathDefended)
- continue;
+ // Since SpaceMask[Us] is fully on our half of the board
+ assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
- pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
- pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
- }
- }
+ // Count safe + (behind & safe) with a single popcount
+ return popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
+ }
- // Step 2. If either side cannot promote at least three plies before the other side then situation
- // becomes too complex and we give up. Otherwise we determine the possibly "winning side"
- if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3)
- return SCORE_ZERO;
- winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
- loserSide = ~winnerSide;
+ // do_evaluate() is the evaluation entry point, called directly from evaluate()
- // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
- b = candidates = pos.pieces(loserSide, PAWN);
+ template<bool Trace>
+ Value do_evaluate(const Position& pos) {
- while (b)
- {
- s = pop_lsb(&b);
+ assert(!pos.checkers());
- // Compute plies from queening
- queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
- movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
- pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
+ EvalInfo ei;
+ Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
+ Thread* thisThread = pos.this_thread();
- // Check if (without even considering any obstacles) we're too far away or doubled
- if ( pliesToQueen[winnerSide] + 3 <= pliesToGo
- || (forward_bb(loserSide, s) & pos.pieces(loserSide, PAWN)))
- candidates ^= s;
- }
+ // Initialize score by reading the incrementally updated scores included
+ // in the position object (material + piece square tables) and adding a
+ // Tempo bonus. Score is computed from the point of view of white.
+ score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
- // If any candidate is already a passed pawn it _may_ promote in time. We give up.
- if (candidates & ei.pi->passed_pawns(loserSide))
- return SCORE_ZERO;
+ // Probe the material hash table
+ ei.mi = Material::probe(pos, thisThread->materialTable, thisThread->endgames);
+ score += ei.mi->material_value();
- // Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
- b = candidates;
+ // If we have a specialized evaluation function for the current material
+ // configuration, call it and return.
+ if (ei.mi->specialized_eval_exists())
+ return ei.mi->evaluate(pos);
- while (b)
- {
- s = pop_lsb(&b);
- sacptg = blockersCount = 0;
- minKingDist = kingptg = 256;
+ // Probe the pawn hash table
+ ei.pi = Pawns::probe(pos, thisThread->pawnsTable);
+ score += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
- // Compute plies from queening
- queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
- movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
- pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
+ // Initialize attack and king safety bitboards
+ init_eval_info<WHITE>(pos, ei);
+ init_eval_info<BLACK>(pos, ei);
- // Generate list of blocking pawns and supporters
- supporters = adjacent_files_bb(file_of(s)) & candidates;
- opposed = forward_bb(loserSide, s) & pos.pieces(winnerSide, PAWN);
- blockers = passed_pawn_mask(loserSide, s) & pos.pieces(winnerSide, PAWN);
+ ei.attackedBy[WHITE][ALL_PIECES] |= ei.attackedBy[WHITE][KING];
+ ei.attackedBy[BLACK][ALL_PIECES] |= ei.attackedBy[BLACK][KING];
- assert(blockers);
+ // Do not include in mobility squares protected by enemy pawns or occupied by our pawns or king
+ Bitboard mobilityArea[] = { ~(ei.attackedBy[BLACK][PAWN] | pos.pieces(WHITE, PAWN, KING)),
+ ~(ei.attackedBy[WHITE][PAWN] | pos.pieces(BLACK, PAWN, KING)) };
- // How many plies does it take to remove all the blocking pawns?
- while (blockers)
- {
- blockSq = pop_lsb(&blockers);
- movesToGo = 256;
+ // Evaluate pieces and mobility
+ score += evaluate_pieces<KNIGHT, WHITE, Trace>(pos, ei, mobility, mobilityArea);
+ score += apply_weight(mobility[WHITE] - mobility[BLACK], Weights[Mobility]);
- // Check pawns that can give support to overcome obstacle, for instance
- // black pawns: a4, b4 white: b2 then pawn in b4 is giving support.
- if (!opposed)
- {
- b2 = supporters & in_front_bb(winnerSide, rank_of(blockSq + pawn_push(winnerSide)));
+ // Evaluate kings after all other pieces because we need complete attack
+ // information when computing the king safety evaluation.
+ score += evaluate_king<WHITE, Trace>(pos, ei)
+ - evaluate_king<BLACK, Trace>(pos, ei);
- while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
- {
- d = square_distance(blockSq, pop_lsb(&b2)) - 2;
- movesToGo = std::min(movesToGo, d);
- }
- }
+ // Evaluate tactical threats, we need full attack information including king
+ score += evaluate_threats<WHITE, Trace>(pos, ei)
+ - evaluate_threats<BLACK, Trace>(pos, ei);
- // Check pawns that can be sacrificed against the blocking pawn
- b2 = pawn_attack_span(winnerSide, blockSq) & candidates & ~(1ULL << s);
+ // Evaluate passed pawns, we need full attack information including king
+ score += evaluate_passed_pawns<WHITE, Trace>(pos, ei)
+ - evaluate_passed_pawns<BLACK, Trace>(pos, ei);
- while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
- {
- d = square_distance(blockSq, pop_lsb(&b2)) - 2;
- movesToGo = std::min(movesToGo, d);
- }
+ // If one side has only a king, score for potential unstoppable pawns
+ if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
+ score += evaluate_unstoppable_pawns(pos, WHITE, ei)
+ - evaluate_unstoppable_pawns(pos, BLACK, ei);
- // If obstacle can be destroyed with an immediate pawn exchange / sacrifice,
- // it's not a real obstacle and we have nothing to add to pliesToGo.
- if (movesToGo <= 0)
- continue;
+ // 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]);
+ }
- // Plies needed to sacrifice against all the blocking pawns
- sacptg += movesToGo * 2;
- blockersCount++;
+ // 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);
- // Plies needed for the king to capture all the blocking pawns
- d = square_distance(pos.king_square(loserSide), blockSq);
- minKingDist = std::min(minKingDist, d);
- kingptg = (minKingDist + blockersCount) * 2;
+ // If we don't already have an unusual scale factor, check for opposite
+ // colored bishop endgames, and use a lower scale for those.
+ if ( ei.mi->game_phase() < PHASE_MIDGAME
+ && pos.opposite_bishops()
+ && (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN))
+ {
+ // Ignoring any pawns, do both sides only have a single bishop and no
+ // other pieces?
+ if ( pos.non_pawn_material(WHITE) == BishopValueMg
+ && pos.non_pawn_material(BLACK) == BishopValueMg)
+ {
+ // Check for KBP vs KB with only a single pawn that is almost
+ // certainly a draw or at least two pawns.
+ bool one_pawn = (pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK) == 1);
+ sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
}
+ else
+ // Endgame with opposite-colored bishops, but also other pieces. Still
+ // a bit drawish, but not as drawish as with only the two bishops.
+ sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
+ }
- // Check if pawn sacrifice plan _may_ save the day
- if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
- return SCORE_ZERO;
+ // Interpolate between a middlegame and a (scaled by 'sf') endgame score
+ Value v = mg_value(score) * int(ei.mi->game_phase())
+ + eg_value(score) * int(PHASE_MIDGAME - ei.mi->game_phase()) * sf / SCALE_FACTOR_NORMAL;
- // Check if king capture plan _may_ save the day (contains some false positives)
- if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
- return SCORE_ZERO;
+ v /= PHASE_MIDGAME;
+
+ // In case of tracing add all single evaluation contributions for both white and black
+ if (Trace)
+ {
+ Tracing::add_term(Tracing::PST, pos.psq_score());
+ Tracing::add_term(Tracing::IMBALANCE, ei.mi->material_value());
+ Tracing::add_term(PAWN, ei.pi->pawns_value());
+ Tracing::add_term(Tracing::MOBILITY, apply_weight(mobility[WHITE], Weights[Mobility])
+ , apply_weight(mobility[BLACK], Weights[Mobility]));
+ Score w = ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei);
+ Score b = ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei);
+ Tracing::add_term(Tracing::SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
+ Tracing::add_term(Tracing::TOTAL, score);
+ Tracing::ei = ei;
+ Tracing::sf = sf;
}
- // Winning pawn is unstoppable and will promote as first, return big score
- Score score = make_score(0, (Value) 1280 - 32 * pliesToQueen[winnerSide]);
- return winnerSide == WHITE ? score : -score;
+ return pos.side_to_move() == WHITE ? v : -v;
}
- // evaluate_space() computes the space evaluation for a given side. The
- // space evaluation is a simple bonus based on the number of safe squares
- // available for minor pieces on the central four files on ranks 2--4. Safe
- // squares one, two or three squares behind a friendly pawn are counted
- // twice. Finally, the space bonus is scaled by a weight taken from the
- // material hash table. The aim is to improve play on game opening.
- template<Color Us>
- int evaluate_space(const Position& pos, EvalInfo& ei) {
+ // Tracing function definitions
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ double Tracing::to_cp(Value v) { return double(v) / PawnValueEg; }
- // Find the safe squares for our pieces inside the area defined by
- // SpaceMask[]. A square is unsafe if it is attacked by an enemy
- // pawn, or if it is undefended and attacked by an enemy piece.
- Bitboard safe = SpaceMask[Us]
- & ~pos.pieces(Us, PAWN)
- & ~ei.attackedBy[Them][PAWN]
- & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
+ void Tracing::add_term(int idx, Score wScore, Score bScore) {
- // Find all squares which are at most three squares behind some friendly pawn
- Bitboard behind = pos.pieces(Us, PAWN);
- behind |= (Us == WHITE ? behind >> 8 : behind << 8);
- behind |= (Us == WHITE ? behind >> 16 : behind << 16);
+ terms[WHITE][idx] = wScore;
+ terms[BLACK][idx] = bScore;
+ }
- // Since SpaceMask[Us] is fully on our half of the board
- assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
+ void Tracing::format_row(std::stringstream& ss, const char* name, int idx) {
- // Count safe + (behind & safe) with a single popcount
- return popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
+ Score wScore = terms[WHITE][idx];
+ Score bScore = terms[BLACK][idx];
+
+ switch (idx) {
+ case PST: case IMBALANCE: case PAWN: case TOTAL:
+ ss << std::setw(20) << name << " | --- --- | --- --- | "
+ << std::setw(5) << to_cp(mg_value(wScore - bScore)) << " "
+ << std::setw(5) << to_cp(eg_value(wScore - bScore)) << " \n";
+ break;
+ default:
+ ss << std::setw(20) << name << " | " << std::noshowpos
+ << std::setw(5) << to_cp(mg_value(wScore)) << " "
+ << std::setw(5) << to_cp(eg_value(wScore)) << " | "
+ << std::setw(5) << to_cp(mg_value(bScore)) << " "
+ << std::setw(5) << to_cp(eg_value(bScore)) << " | "
+ << std::setw(5) << to_cp(mg_value(wScore - bScore)) << " "
+ << std::setw(5) << to_cp(eg_value(wScore - bScore)) << " \n";
+ }
}
+ std::string Tracing::do_trace(const Position& pos) {
- // interpolate() interpolates between a middle game and an endgame score,
- // based on game phase. It also scales the return value by a ScaleFactor array.
+ std::memset(terms, 0, sizeof(terms));
- Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {
+ Value v = do_evaluate<true>(pos);
+ v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
- assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
- assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
- assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
+ std::stringstream ss;
+ ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
+ << " Eval term | White | Black | Total \n"
+ << " | MG EG | MG EG | MG EG \n"
+ << "---------------------+-------------+-------------+-------------\n";
- int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
- int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
- return Value((result / GrainSize) * GrainSize); // Sign independent
- }
+ format_row(ss, "Material, PST, Tempo", PST);
+ format_row(ss, "Material imbalance", IMBALANCE);
+ format_row(ss, "Pawns", PAWN);
+ format_row(ss, "Knights", KNIGHT);
+ format_row(ss, "Bishops", BISHOP);
+ format_row(ss, "Rooks", ROOK);
+ format_row(ss, "Queens", QUEEN);
+ format_row(ss, "Mobility", MOBILITY);
+ format_row(ss, "King safety", KING);
+ format_row(ss, "Threats", THREAT);
+ format_row(ss, "Passed pawns", PASSED);
+ format_row(ss, "Space", SPACE);
+
+ ss << "---------------------+-------------+-------------+-------------\n";
+ format_row(ss, "Total", TOTAL);
+
+ ss << "\nTotal Evaluation: " << to_cp(v) << " (white side)\n";
- // apply_weight() weights score v by score w trying to prevent overflow
- Score apply_weight(Score v, Score w) {
- return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
- (int(eg_value(v)) * eg_value(w)) / 0x100);
+ return ss.str();
}
- // weight_option() computes the value of an evaluation weight, by combining
- // two UCI-configurable weights (midgame and endgame) with an internal weight.
+} // namespace
- Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
- // Scale option value from 100 to 256
- int mg = Options[mgOpt] * 256 / 100;
- int eg = Options[egOpt] * 256 / 100;
+namespace Eval {
- return apply_weight(make_score(mg, eg), internalWeight);
+ /// evaluate() is the main evaluation function. It returns a static evaluation
+ /// of the position always from the point of view of the side to move.
+
+ Value evaluate(const Position& pos) {
+ return do_evaluate<false>(pos);
}
- // Tracing functions definitions
+ /// trace() is like evaluate(), but instead of returning a value, it returns
+ /// a string (suitable for outputting to stdout) that contains the detailed
+ /// descriptions and values of each evaluation term. It's mainly used for
+ /// debugging.
+ std::string trace(const Position& pos) {
+ return Tracing::do_trace(pos);
+ }
- double to_cp(Value v) { return double(v) / double(PawnValueMg); }
- void Tracing::add(int idx, Score wScore, Score bScore) {
+ /// init() computes evaluation weights from the corresponding UCI parameters
+ /// and setup king tables.
+
+ void init() {
- scores[WHITE][idx] = wScore;
- scores[BLACK][idx] = bScore;
- }
+ Weights[Mobility] = weight_option("Mobility (Midgame)", "Mobility (Endgame)", WeightsInternal[Mobility]);
+ Weights[PawnStructure] = weight_option("Pawn Structure (Midgame)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
+ Weights[PassedPawns] = weight_option("Passed Pawns (Midgame)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
+ Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
+ Weights[KingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
+ Weights[KingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
- void Tracing::row(const char* name, int idx) {
+ const double MaxSlope = 30;
+ const double Peak = 1280;
- Score wScore = scores[WHITE][idx];
- Score bScore = scores[BLACK][idx];
+ for (int t = 0, i = 1; i < 100; ++i)
+ {
+ t = int(std::min(Peak, std::min(0.4 * i * i, t + MaxSlope)));
- switch (idx) {
- case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
- stream << std::setw(20) << name << " | --- --- | --- --- | "
- << std::setw(6) << to_cp(mg_value(wScore)) << " "
- << std::setw(6) << to_cp(eg_value(wScore)) << " \n";
- break;
- default:
- stream << std::setw(20) << name << " | " << std::noshowpos
- << std::setw(5) << to_cp(mg_value(wScore)) << " "
- << std::setw(5) << to_cp(eg_value(wScore)) << " | "
- << std::setw(5) << to_cp(mg_value(bScore)) << " "
- << std::setw(5) << to_cp(eg_value(bScore)) << " | "
- << std::showpos
- << std::setw(6) << to_cp(mg_value(wScore - bScore)) << " "
- << std::setw(6) << to_cp(eg_value(wScore - bScore)) << " \n";
+ KingDanger[1][i] = apply_weight(make_score(t, 0), Weights[KingDangerUs]);
+ KingDanger[0][i] = apply_weight(make_score(t, 0), Weights[KingDangerThem]);
}
}
- std::string Tracing::do_trace(const Position& pos) {
-
- stream.str("");
- stream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
- std::memset(scores, 0, 2 * (TOTAL + 1) * sizeof(Score));
-
- Value margin;
- do_evaluate<true>(pos, margin);
-
- std::string totals = stream.str();
- stream.str("");
-
- stream << std::setw(21) << "Eval term " << "| White | Black | Total \n"
- << " | MG EG | MG EG | MG EG \n"
- << "---------------------+-------------+-------------+---------------\n";
-
- row("Material, PST, Tempo", PST);
- row("Material imbalance", IMBALANCE);
- row("Pawns", PAWN);
- row("Knights", KNIGHT);
- row("Bishops", BISHOP);
- row("Rooks", ROOK);
- row("Queens", QUEEN);
- row("Mobility", MOBILITY);
- row("King safety", KING);
- row("Threats", THREAT);
- row("Passed pawns", PASSED);
- row("Unstoppable pawns", UNSTOPPABLE);
- row("Space", SPACE);
-
- stream << "---------------------+-------------+-------------+---------------\n";
- row("Total", TOTAL);
- stream << totals;
-
- return stream.str();
- }
-}
+} // namespace Eval
projects / stockfish / blobdiff