/*
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) 2008-2015 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm>
#include <cassert>
+#include <cstring> // For std::memset
#include <iomanip>
#include <sstream>
-#include <algorithm>
#include "bitcount.h"
#include "evaluate.h"
#include "material.h"
#include "pawns.h"
-#include "thread.h"
-#include "ucioption.h"
namespace {
- enum ExtendedPieceType { // Used for tracing
- PST = 8, IMBALANCE, MOBILITY, THREAT, PASSED, UNSTOPPABLE, SPACE, TOTAL
- };
+ namespace Trace {
+
+ enum Term { // First 8 entries are for PieceType
+ MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
+ };
+
+ double scores[TERM_NB][COLOR_NB][PHASE_NB];
- namespace Tracing {
+ double to_cp(Value v) { return double(v) / PawnValueEg; }
- Score scores[COLOR_NB][TOTAL + 1];
- std::stringstream stream;
+ void add(int idx, Color c, Score s) {
+ scores[idx][c][MG] = to_cp(mg_value(s));
+ scores[idx][c][EG] = to_cp(eg_value(s));
+ }
+
+ void add(int idx, Score w, Score b = SCORE_ZERO) {
+ add(idx, WHITE, w); add(idx, BLACK, b);
+ }
- 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);
+ std::ostream& operator<<(std::ostream& os, Term t) {
+
+ if (t == MATERIAL || t == IMBALANCE || t == Term(PAWN) || t == TOTAL)
+ os << " --- --- | --- --- | ";
+ else
+ os << std::setw(5) << scores[t][WHITE][MG] << " "
+ << std::setw(5) << scores[t][WHITE][EG] << " | "
+ << std::setw(5) << scores[t][BLACK][MG] << " "
+ << std::setw(5) << scores[t][BLACK][EG] << " | ";
+
+ os << std::setw(5) << scores[t][WHITE][MG] - scores[t][BLACK][MG] << " "
+ << std::setw(5) << scores[t][WHITE][EG] - scores[t][BLACK][EG] << " \n";
+
+ return os;
+ }
}
+ using namespace Trace;
+
// Struct EvalInfo contains various information computed and collected
// by the evaluation functions.
struct EvalInfo {
- // Pointers to material and pawn hash table entries
- Material::Entry* mi;
- Pawns::Entry* pi;
-
// attackedBy[color][piece type] is a bitboard representing all squares
- // attacked by a given color and piece type, attackedBy[color][ALL_PIECES]
- // contains all squares attacked by the given color.
+ // attacked by a given color and piece type (can be also ALL_PIECES).
Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
// kingRing[color] is the zone around the king which is considered
// kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
// given color which attack a square in the kingRing of the enemy king. The
- // weights of the individual piece types are given by the variables
- // QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
- // KnightAttackWeight in evaluate.cpp
+ // weights of the individual piece types are given by the elements in the
+ // KingAttackWeights array.
int kingAttackersWeight[COLOR_NB];
- // kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
- // directly adjacent to the king of the given color. Pieces which attack
- // more than one square are counted multiple times. For instance, if black's
- // king is on g8 and there's a white knight on g5, this knight adds
- // 2 to kingAdjacentZoneAttacksCount[BLACK].
+ // kingAdjacentZoneAttacksCount[color] is the number of attacks by the given
+ // color to squares directly adjacent to the enemy king. Pieces which attack
+ // more than one square are counted multiple times. For instance, if there is
+ // a white knight on g5 and black's king is on g8, this white knight adds 2
+ // to kingAdjacentZoneAttacksCount[WHITE].
int kingAdjacentZoneAttacksCount[COLOR_NB];
- };
- // Evaluation grain size, must be a power of 2
- const int GrainSize = 4;
+ Bitboard pinnedPieces[COLOR_NB];
+ Pawns::Entry* pi;
+ };
- // Evaluation weights, initialized from UCI options
- enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
- Score Weights[6];
- typedef Value V;
- #define S(mg, eg) make_score(mg, eg)
+ // Evaluation weights, indexed by the corresponding evaluation term
+ enum { Mobility, PawnStructure, PassedPawns, Space, KingSafety };
- // Internal evaluation weights. These are applied on top of the evaluation
- // weights read from UCI parameters. The purpose is to be able to change
- // the evaluation weights while keeping the default values of the UCI
- // parameters at 100, which looks prettier.
- //
- // 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)
+ const struct Weight { int mg, eg; } Weights[] = {
+ {289, 344}, {233, 201}, {221, 273}, {46, 0}, {322, 0}
};
+ Score operator*(Score s, const Weight& w) {
+ return make_score(mg_value(s) * w.mg / 256, eg_value(s) * w.eg / 256);
+ }
+
+
+ #define V(v) Value(v)
+ #define S(mg, eg) make_score(mg, eg)
+
// 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(-70,-52), S(-52,-37), S( -7,-17), S( 0, -6), S( 8, 5), S( 16, 9), // Knights
+ S( 23, 20), S( 31, 21), S( 36, 22) },
+ { S(-49,-44), S(-22,-13), S( 16, 0), S( 27, 11), S( 38, 19), S( 52, 34), // Bishops
+ S( 56, 44), S( 65, 47), S( 67, 51), S( 73, 56), S( 81, 59), S( 83, 69),
+ S( 95, 72), S(100, 75) },
+ { S(-49,-57), S(-22,-14), S(-10, 18), S( -5, 39), S( -4, 50), S( -2, 58), // Rooks
+ S( 6, 78), S( 11, 86), S( 17, 92), S( 19,103), S( 26,111), S( 27,115),
+ S( 36,119), S( 41,121), S( 50,122) },
+ { S(-41,-24), S(-26, -8), S( 0, 6), S( 2, 14), S( 12, 27), S( 21, 40), // Queens
+ S( 22, 45), S( 37, 55), S( 40, 57), S( 43, 63), S( 50, 68), S( 52, 74),
+ S( 56, 80), S( 66, 84), S( 68, 85), S( 69, 88), S( 71, 92), S( 72, 94),
+ S( 80, 96), S( 89, 98), S( 94,101), S(102,113), S(106,114), S(107,116),
+ S(112,125), S(113,127), S(117,137), S(122,143) }
};
- // Outpost[PieceType][Square] contains bonuses of knights and bishops, 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
- 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),
- V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
- V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
- V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },
- {
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
- V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
- V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
- V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
- V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }
+ // Outpost[knight/bishop][supported by pawn] contains bonuses for knights and
+ // bishops outposts, bigger if outpost piece is supported by a pawn.
+ const Score Outpost[][2] = {
+ { S(42,11), S(63,17) }, // Knights
+ { S(18, 5), S(27, 8) } // Bishops
};
- // 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
+ // Threat[minor/rook][attacked PieceType] contains
+ // bonuses according to which piece type attacks which one.
+ // Attacks on lesser pieces which are pawn defended are not considered.
+ const Score Threat[2][PIECE_TYPE_NB] = {
+ { S(0, 0), S(0, 32), S(25, 39), S(28, 44), S(42, 98), S(35,105) }, // Minor attacks
+ { S(0, 0), S(0, 27), S(26, 57), S(26, 57), S( 0, 30), S(23, 51) } // Rook attacks
};
// ThreatenedByPawn[PieceType] contains a penalty according to which piece
- // type is attacked by an enemy pawn.
- const Score ThreatenedByPawn[] = {
- S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
+ // type is attacked by a pawn.
+ const Score ThreatenedByPawn[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 0), S(107, 138), S(84, 122), S(114, 203), S(121, 217)
};
- #undef S
+ // Passed[mg/eg][rank] contains midgame and endgame bonuses for passed pawns.
+ // We don't use a Score because we process the two components independently.
+ const Value Passed[][RANK_NB] = {
+ { V(0), V( 1), V(34), V(90), V(214), V(328) },
+ { V(7), V(14), V(37), V(63), V(134), V(189) }
+ };
- 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 UndefendedMinor = make_score(25, 10);
- const Score TrappedRook = make_score(90, 0);
+ // PassedFile[File] contains a bonus according to the file of a passed pawn.
+ const Score PassedFile[] = {
+ S( 12, 10), S( 3, 10), S( 1, -8), S(-27, -12),
+ S(-27, -12), S( 1, -8), S( 3, 10), S( 12, 10)
+ };
+
+ const Score ThreatenedByHangingPawn = S(40, 60);
+
+ // Assorted bonuses and penalties used by evaluation
+ const Score KingOnOne = S( 2, 58);
+ const Score KingOnMany = S( 6,125);
+ const Score RookOnPawn = S( 7, 27);
+ const Score RookOnOpenFile = S(43, 21);
+ const Score RookOnSemiOpenFile = S(19, 10);
+ const Score BishopPawns = S( 8, 12);
+ const Score MinorBehindPawn = S(16, 0);
+ const Score TrappedRook = S(92, 0);
+ const Score Unstoppable = S( 0, 20);
+ const Score Hanging = S(31, 26);
+ const Score PawnAttackThreat = S(20, 20);
+ const Score Checked = S(20, 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);
+ const Score TrappedBishopA1H1 = S(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
+ #undef S
+ #undef V
+
+ // 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)
- };
-
- // 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[].
- //
- // 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 Bitboard SpaceMask[COLOR_NB] = {
+ (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB),
+ (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB)
};
- // 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);
- }
-
-
- /// 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(make_score(s * ei.mi->space_weight(), 0), 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);
- }
-
- margin = margins[pos.side_to_move()];
- Value v = interpolate(score, ei.mi->game_phase(), sf);
+ // King danger constants and variables. The king danger scores are looked-up
+ // in 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[].
+ Score KingDanger[512];
- // 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 = make_score(ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei), 0);
- Score b = make_score(ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei), 0);
- 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);
- }
+ // KingAttackWeights[PieceType] contains king attack weights by piece type
+ const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 7, 5, 4, 1 };
- return pos.side_to_move() == WHITE ? v : -v;
-}
+ // Penalties for enemy's safe checks
+ const int QueenContactCheck = 89;
+ const int QueenCheck = 50;
+ const int RookCheck = 45;
+ const int BishopCheck = 6;
+ const int KnightCheck = 14;
// init_eval_info() initializes king bitboards for given color adding
template<Color Us>
void init_eval_info(const Position& pos, EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
- Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
- ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
+ ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
+ Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.square<KING>(Them));
+ ei.attackedBy[Them][ALL_PIECES] |= b;
+ 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)
+ if (pos.non_pawn_material(Us) >= QueenValueMg)
{
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
- ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
- }
-
-
- // evaluate_outposts() evaluates bishop and knight outposts squares
-
- template<PieceType Piece, Color Us>
- Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
-
- const Color Them = (Us == WHITE ? BLACK : WHITE);
-
- assert (Piece == BISHOP || Piece == KNIGHT);
-
- // Initial bonus based on square
- 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.
- if (bonus && (ei.attackedBy[Us][PAWN] & s))
- {
- if ( !pos.pieces(Them, KNIGHT)
- && !(same_color_squares(s) & pos.pieces(Them, BISHOP)))
- bonus += bonus + bonus / 2;
- else
- bonus += bonus / 2;
}
- return make_score(bonus, bonus);
+ else
+ ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
}
- // 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 DoTrace>
+ Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility, const 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.squares<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);
- ei.attackedBy[Us][Piece] |= b;
+ if (ei.pinnedPieces[Us] & s)
+ b &= LineBB[pos.square<KING>(Us)][s];
+
+ 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 = popcount<Piece == QUEEN ? Full : Max15>(b & mobilityArea);
- mobility += MobilityBonus[Piece][mob];
-
- // Decrease score if we are attacked by an enemy pawn. 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;
+ if (Pt == QUEEN)
+ b &= ~( ei.attackedBy[Them][KNIGHT]
+ | ei.attackedBy[Them][BISHOP]
+ | ei.attackedBy[Them][ROOK]);
- // Penalty for bishop with same coloured pawns
- if (Piece == BISHOP)
- score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
+ int mob = popcount<Pt == QUEEN ? Full : Max15>(b & mobilityArea[Us]);
- // Bishop and knight outposts squares
- if ( (Piece == BISHOP || Piece == KNIGHT)
- && !(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
- score += evaluate_outposts<Piece, Us>(pos, ei, s);
+ mobility[Us] += MobilityBonus[Pt][mob];
- if ( (Piece == ROOK || Piece == QUEEN)
- && relative_rank(Us, s) >= RANK_5)
+ if (Pt == BISHOP || Pt == KNIGHT)
{
- // 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);
+ // Bonus for outpost square
+ if ( relative_rank(Us, s) >= RANK_4
+ && relative_rank(Us, s) <= RANK_6
+ && !(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
+ score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & s)];
+
+ // Bonus when behind a pawn
+ if ( relative_rank(Us, s) < RANK_5
+ && (pos.pieces(PAWN) & (s + pawn_push(Us))))
+ score += MinorBehindPawn;
+
+ // Penalty for pawns on same color square of bishop
+ if (Pt == BISHOP)
+ score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
+
+ // 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 ( Pt == BISHOP
+ && pos.is_chess960()
+ && (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
+ {
+ Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
+ 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;
+ }
}
- // Special extra evaluation for rooks
- if (Piece == ROOK)
+ if (Pt == 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 (mob > 6 || ei.pi->semiopen(Us, file_of(s)))
- continue;
+ // Bonus for aligning with enemy pawns on the same rank/file
+ if (relative_rank(Us, s) >= RANK_5)
+ {
+ Bitboard alignedPawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
+ if (alignedPawns)
+ score += popcount<Max15>(alignedPawns) * RookOnPawn;
+ }
- Square ksq = pos.king_square(Us);
+ // Bonus when on an open or semi-open file
+ if (ei.pi->semiopen_file(Us, file_of(s)))
+ score += ei.pi->semiopen_file(Them, file_of(s)) ? RookOnOpenFile : RookOnSemiOpenFile;
- // Penalize rooks which are trapped inside a king. Penalize more if
- // king has lost right to castle.
- 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);
- }
+ // Penalize when trapped by the king, even more if king cannot castle
+ if (mob <= 3 && !ei.pi->semiopen_file(Us, file_of(s)))
+ {
+ Square ksq = pos.square<KING>(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
- && 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 ( ((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_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
+ score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
+ }
}
}
- if (Trace)
- Tracing::scores[Us][Piece] = 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, EvalInfo& ei) {
+ if (DoTrace)
+ Trace::add(Pt, Us, score);
- 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;
+ // Recursively call evaluate_pieces() of next piece type until KING excluded
+ return score - evaluate_pieces<NextPt, Them, DoTrace>(pos, ei, mobility, mobilityArea);
}
+ template<>
+ Score evaluate_pieces<KING, WHITE, false>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
+ template<>
+ Score evaluate_pieces<KING, WHITE, true>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
- // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
- // pieces 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]);
+ // evaluate_king() assigns bonuses and penalties to a king of a given color
- 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[]) {
+ template<Color Us, bool DoTrace>
+ Score evaluate_king(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
Bitboard undefended, b, b1, b2, safe;
int attackUnits;
- const Square ksq = pos.king_square(Us);
+ const Square ksq = pos.square<KING>(Us);
// 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
+ // index into 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)
- + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
- + KingExposed[relative_square(Us, ksq)]
- - mg_value(score) / 32;
-
- // Analyse enemy's safe queen contact checks. First find undefended
- // squares around the king attacked by enemy queen...
+ // attacked and undefended squares around our king and the quality of
+ // the pawn shelter (current 'score' value).
+ attackUnits = std::min(72, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
+ + 9 * ei.kingAdjacentZoneAttacksCount[Them]
+ + 27 * popcount<Max15>(undefended)
+ + 11 * !!ei.pinnedPieces[Us]
+ - 64 * !pos.count<QUEEN>(Them)
+ - mg_value(score) / 8;
+
+ // Analyse the enemy's safe queen contact checks. Firstly, find the
+ // undefended squares around the king reachable by the enemy queen...
b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
if (b)
{
- // ...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...
- b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
+ // ...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]
+ | ei.attackedBy[Them][KING];
- // Consider only squares where the enemy rook gives check
- b &= PseudoAttacks[ROOK][ksq];
-
- if (b)
- {
- // ...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);
+ attackUnits += QueenContactCheck * popcount<Max15>(b);
}
- // Analyse enemy's safe distance checks for sliders and knights
- safe = ~(pos.pieces(Them) | ei.attackedBy[Us][ALL_PIECES]);
+ // Analyse the enemy's safe distance checks for sliders and knights
+ safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
- b1 = pos.attacks_from<ROOK>(ksq) & safe;
+ b1 = pos.attacks_from<ROOK >(ksq) & safe;
b2 = pos.attacks_from<BISHOP>(ksq) & safe;
// Enemy queen safe checks
b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
if (b)
+ {
attackUnits += QueenCheck * popcount<Max15>(b);
+ score -= Checked;
+ }
// Enemy rooks safe checks
b = b1 & ei.attackedBy[Them][ROOK];
if (b)
+ {
attackUnits += RookCheck * popcount<Max15>(b);
+ score -= Checked;
+ }
// Enemy bishops safe checks
b = b2 & ei.attackedBy[Them][BISHOP];
if (b)
+ {
attackUnits += BishopCheck * popcount<Max15>(b);
+ score -= Checked;
+ }
// Enemy knights safe checks
b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
if (b)
+ {
attackUnits += KnightCheck * popcount<Max15>(b);
-
- // To index KingDanger[] attackUnits must be in [0, 99] range
- attackUnits = std::min(99, std::max(0, attackUnits));
+ score -= Checked;
+ }
// 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.
- score -= KingDanger[Us == Search::RootColor][attackUnits];
- margins[Us] += mg_value(KingDanger[Us == Search::RootColor][attackUnits]);
+ // array and subtract the score from evaluation.
+ score -= KingDanger[std::max(std::min(attackUnits, 399), 0)];
}
- if (Trace)
- Tracing::scores[Us][KING] = score;
+ if (DoTrace)
+ Trace::add(KING, Us, score);
return score;
}
- // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
+ // evaluate_threats() assigns bonuses according to the type of attacking piece
+ // and the type of attacked one.
- template<Color Us, bool Trace>
- Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
+ template<Color Us, bool DoTrace>
+ Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
+ const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
+ const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
+ const Bitboard TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
+ const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
+ enum { Minor, Rook };
+
+ Bitboard b, weak, defended, safeThreats;
Score score = SCORE_ZERO;
- b = ei.pi->passed_pawns(Us);
+ // Non-pawn enemies attacked by a pawn
+ weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];
- while (b)
+ if (weak)
{
- Square s = pop_lsb(&b);
-
- assert(pos.pawn_is_passed(Us, s));
-
- int r = int(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));
-
- 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);
-
- // 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 the pawn is free to advance, increase bonus
- if (pos.is_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
- // the squares in the pawn's path attacked or occupied by the enemy.
- if (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN) & pos.attacks_from<ROOK>(s))
- unsafeSquares = squaresToQueen;
- 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;
-
- // Big bonus if the path to queen is fully defended, a bit less
- // if at least block square is defended.
- if (defendedSquares == squaresToQueen)
- k += 6;
-
- else if (defendedSquares & blockSq)
- k += (unsafeSquares & defendedSquares) == unsafeSquares ? 4 : 2;
+ b = pos.pieces(Us, PAWN) & ( ~ei.attackedBy[Them][ALL_PIECES]
+ | ei.attackedBy[Us][ALL_PIECES]);
- mbonus += Value(k * rr), ebonus += Value(k * rr);
- }
- } // rr != 0
+ safeThreats = (shift_bb<Right>(b) | shift_bb<Left>(b)) & weak;
- // 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 (weak ^ safeThreats)
+ score += ThreatenedByHangingPawn;
+ while (safeThreats)
+ score += ThreatenedByPawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
}
- if (Trace)
- Tracing::scores[Us][PASSED] = apply_weight(score, Weights[PassedPawns]);
+ // Non-pawn enemies defended by a pawn
+ defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Them][PAWN];
- // Add the scores to the middle game and endgame eval
- return apply_weight(score, Weights[PassedPawns]);
- }
+ // Enemies not defended by a pawn and under our attack
+ weak = pos.pieces(Them)
+ & ~ei.attackedBy[Them][PAWN]
+ & ei.attackedBy[Us][ALL_PIECES];
-
- // 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.
-
- Score evaluate_unstoppable_pawns(const Position& pos, 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 };
-
- // 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++)
+ // Add a bonus according to the kind of attacking pieces
+ if (defended | weak)
{
- // Skip if other side has non-pawn pieces
- if (pos.non_pawn_material(~c))
- continue;
-
- b = ei.pi->passed_pawns(c);
+ b = (defended | weak) & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+ while (b)
+ score += Threat[Minor][type_of(pos.piece_on(pop_lsb(&b)))];
+ b = (pos.pieces(Them, QUEEN) | weak) & ei.attackedBy[Us][ROOK];
while (b)
- {
- s = pop_lsb(&b);
- queeningSquare = relative_square(c, file_of(s) | RANK_8);
- queeningPath = forward_bb(c, s);
+ score += Threat[Rook ][type_of(pos.piece_on(pop_lsb(&b)))];
- // 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);
+ b = weak & ~ei.attackedBy[Them][ALL_PIECES];
+ if (b)
+ score += Hanging * popcount<Max15>(b);
- if (movesToGo >= oppMovesToGo && !pathDefended)
- continue;
+ b = weak & ei.attackedBy[Us][KING];
+ if (b)
+ score += more_than_one(b) ? KingOnMany : KingOnOne;
+ }
- // 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)));
+ // Bonus if some pawns can safely push and attack an enemy piece
+ b = pos.pieces(Us, PAWN) & ~TRank7BB;
+ b = shift_bb<Up>(b | (shift_bb<Up>(b & TRank2BB) & ~pos.pieces()));
- // Add moves needed to free the path from friendly pieces and retest condition
- movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
+ b &= ~pos.pieces()
+ & ~ei.attackedBy[Them][PAWN]
+ & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
- if (movesToGo >= oppMovesToGo && !pathDefended)
- continue;
+ b = (shift_bb<Left>(b) | shift_bb<Right>(b))
+ & pos.pieces(Them)
+ & ~ei.attackedBy[Us][PAWN];
- pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
- pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
- }
- }
+ if (b)
+ score += popcount<Max15>(b) * PawnAttackThreat;
- // 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;
+ if (DoTrace)
+ Trace::add(THREAT, Us, score);
- winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
- loserSide = ~winnerSide;
+ return score;
+ }
- // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
- b = candidates = pos.pieces(loserSide, PAWN);
- while (b)
- {
- s = pop_lsb(&b);
+ // evaluate_passed_pawns() evaluates the passed pawns of the given color
- // 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());
+ template<Color Us, bool DoTrace>
+ Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
- // 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;
- }
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
- // 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;
+ Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
+ Score score = SCORE_ZERO;
- // Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
- b = candidates;
+ b = ei.pi->passed_pawns(Us);
while (b)
{
- s = pop_lsb(&b);
- sacptg = blockersCount = 0;
- minKingDist = kingptg = 256;
+ Square s = pop_lsb(&b);
- // 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());
+ assert(pos.pawn_passed(Us, s));
- // 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);
+ int r = relative_rank(Us, s) - RANK_2;
+ int rr = r * (r - 1);
- assert(blockers);
+ Value mbonus = Passed[MG][r], ebonus = Passed[EG][r];
- // How many plies does it take to remove all the blocking pawns?
- while (blockers)
+ if (rr)
{
- blockSq = pop_lsb(&blockers);
- movesToGo = 256;
+ Square blockSq = s + pawn_push(Us);
- // 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)
+ // Adjust bonus based on the king's proximity
+ ebonus += distance(pos.square<KING>(Them), blockSq) * 5 * rr
+ - distance(pos.square<KING>(Us ), blockSq) * 2 * rr;
+
+ // If blockSq is not the queening square then consider also a second push
+ if (relative_rank(Us, blockSq) != RANK_8)
+ ebonus -= distance(pos.square<KING>(Us), blockSq + pawn_push(Us)) * rr;
+
+ // If the pawn is free to advance, then increase the bonus
+ if (pos.empty(blockSq))
{
- b2 = supporters & in_front_bb(winnerSide, blockSq + pawn_push(winnerSide));
+ // If there is a rook or queen attacking/defending the pawn from behind,
+ // consider all the squaresToQueen. Otherwise consider only the squares
+ // in the pawn's path attacked or occupied by the enemy.
+ defendedSquares = unsafeSquares = squaresToQueen = forward_bb(Us, s);
- 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);
- }
- }
+ Bitboard bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
- // Check pawns that can be sacrificed against the blocking pawn
- b2 = pawn_attack_span(winnerSide, blockSq) & candidates & ~(1ULL << s);
+ if (!(pos.pieces(Us) & bb))
+ defendedSquares &= ei.attackedBy[Us][ALL_PIECES];
- 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 (!(pos.pieces(Them) & bb))
+ unsafeSquares &= ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
- // 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;
+ // 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 ? 18 : !(unsafeSquares & blockSq) ? 8 : 0;
- // Plies needed to sacrifice against all the blocking pawns
- sacptg += movesToGo * 2;
- blockersCount++;
+ // 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;
- // 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;
- }
+ else if (defendedSquares & blockSq)
+ k += 4;
- // Check if pawn sacrifice plan _may_ save the day
- if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
- return SCORE_ZERO;
+ mbonus += k * rr, ebonus += k * rr;
+ }
+ else if (pos.pieces(Us) & blockSq)
+ mbonus += rr * 3 + r * 2 + 3, ebonus += rr + r * 2;
+ } // rr != 0
- // Check if king capture plan _may_ save the day (contains some false positives)
- if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
- return SCORE_ZERO;
+ if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
+ ebonus += ebonus / 4;
+
+ score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
}
- // 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;
+ if (DoTrace)
+ Trace::add(PASSED, Us, score * Weights[PassedPawns]);
+
+ // Add the scores to the middlegame and endgame eval
+ return score * Weights[PassedPawns];
}
// 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.
+ // twice. Finally, the space bonus is multiplied by a weight. The aim is to
+ // improve play on game opening.
template<Color Us>
- int evaluate_space(const Position& pos, EvalInfo& ei) {
+ Score evaluate_space(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
behind |= (Us == WHITE ? behind >> 8 : behind << 8);
behind |= (Us == WHITE ? behind >> 16 : behind << 16);
- // Since SpaceMask[Us] is fully on our half of the board
+ // Since SpaceMask[Us] is fully on our half of the board...
assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
- // Count safe + (behind & safe) with a single popcount
- return popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
+ // ...count safe + (behind & safe) with a single popcount
+ int bonus = popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
+ int weight = pos.count<KNIGHT>(Us) + pos.count<BISHOP>(Us)
+ + pos.count<KNIGHT>(Them) + pos.count<BISHOP>(Them);
+
+ return make_score(bonus * weight * weight, 0);
}
- // interpolate() interpolates between a middle game and an endgame score,
- // based on game phase. It also scales the return value by a ScaleFactor array.
+ // evaluate_initiative() computes the initiative correction value for the
+ // position, i.e. second order bonus/malus based on the known attacking/defending
+ // status of the players.
+ Score evaluate_initiative(const Position& pos, const EvalInfo& ei, const Score positional_score) {
- Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {
+ int king_separation = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
+ int pawns = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK);
+ int asymmetry = ei.pi->pawn_asymmetry();
- 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);
+ // Compute the initiative bonus for the attacking side
+ int attacker_bonus = 8 * (pawns + asymmetry + king_separation) - 120;
- 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 / 2) & ~(GrainSize - 1));
- }
+ // Now apply the bonus: note that we find the attacking side by extracting the sign
+ // of the endgame value of "positional_score", and that we carefully cap the bonus so
+ // that the endgame score with the correction will never be divided by more than two.
+ int eg = eg_value(positional_score);
+ int value = ((eg > 0) - (eg < 0)) * std::max(attacker_bonus, -abs(eg / 2));
- // 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 make_score(0, value);
}
- // 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;
+/// 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.
- return apply_weight(make_score(mg, eg), internalWeight);
- }
+template<bool DoTrace>
+Value Eval::evaluate(const Position& pos) {
+
+ assert(!pos.checkers());
+
+ EvalInfo ei;
+ Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
+
+ // Initialize score by reading the incrementally updated scores included
+ // in the position object (material + piece square tables).
+ // Score is computed from the point of view of white.
+ score = pos.psq_score();
+ // Probe the material hash table
+ Material::Entry* me = Material::probe(pos);
+ score += me->imbalance();
+
+ // If we have a specialized evaluation function for the current material
+ // configuration, call it and return.
+ if (me->specialized_eval_exists())
+ return me->evaluate(pos);
+
+ // Probe the pawn hash table
+ ei.pi = Pawns::probe(pos);
+ score += ei.pi->pawns_score() * Weights[PawnStructure];
+
+ // Initialize attack and king safety bitboards
+ ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
+ init_eval_info<WHITE>(pos, ei);
+ init_eval_info<BLACK>(pos, ei);
+
+ // Pawns blocked or on ranks 2 and 3. Will be excluded from the mobility area
+ Bitboard blockedPawns[] = {
+ pos.pieces(WHITE, PAWN) & (shift_bb<DELTA_S>(pos.pieces()) | Rank2BB | Rank3BB),
+ pos.pieces(BLACK, PAWN) & (shift_bb<DELTA_N>(pos.pieces()) | Rank7BB | Rank6BB)
+ };
+
+ // Do not include in mobility squares protected by enemy pawns, or occupied
+ // by our blocked pawns or king.
+ Bitboard mobilityArea[] = {
+ ~(ei.attackedBy[BLACK][PAWN] | blockedPawns[WHITE] | pos.square<KING>(WHITE)),
+ ~(ei.attackedBy[WHITE][PAWN] | blockedPawns[BLACK] | pos.square<KING>(BLACK))
+ };
+
+ // Evaluate pieces and mobility
+ score += evaluate_pieces<KNIGHT, WHITE, DoTrace>(pos, ei, mobility, mobilityArea);
+ score += (mobility[WHITE] - mobility[BLACK]) * Weights[Mobility];
+
+ // Evaluate kings after all other pieces because we need complete attack
+ // information when computing the king safety evaluation.
+ score += evaluate_king<WHITE, DoTrace>(pos, ei)
+ - evaluate_king<BLACK, DoTrace>(pos, ei);
- // Tracing functions definitions
+ // Evaluate tactical threats, we need full attack information including king
+ score += evaluate_threats<WHITE, DoTrace>(pos, ei)
+ - evaluate_threats<BLACK, DoTrace>(pos, ei);
- double to_cp(Value v) { return double(v) / double(PawnValueMg); }
+ // Evaluate passed pawns, we need full attack information including king
+ score += evaluate_passed_pawns<WHITE, DoTrace>(pos, ei)
+ - evaluate_passed_pawns<BLACK, DoTrace>(pos, ei);
- void Tracing::add(int idx, Score wScore, Score bScore) {
+ // If both sides have only pawns, score for potential unstoppable pawns
+ if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
+ {
+ Bitboard b;
+ if ((b = ei.pi->passed_pawns(WHITE)) != 0)
+ score += int(relative_rank(WHITE, frontmost_sq(WHITE, b))) * Unstoppable;
- scores[WHITE][idx] = wScore;
- scores[BLACK][idx] = bScore;
+ if ((b = ei.pi->passed_pawns(BLACK)) != 0)
+ score -= int(relative_rank(BLACK, frontmost_sq(BLACK, b))) * Unstoppable;
}
- void Tracing::row(const char* name, int idx) {
-
- Score wScore = scores[WHITE][idx];
- Score bScore = scores[BLACK][idx];
-
- 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";
- }
+ // Evaluate space for both sides, only during opening
+ if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
+ score += (evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei)) * Weights[Space];
+
+ // Evaluate initiative
+ score += evaluate_initiative(pos, ei, score);
+
+ // Scale winning side if position is more drawish than it appears
+ Color strongSide = eg_value(score) > VALUE_DRAW ? WHITE : BLACK;
+ ScaleFactor sf = me->scale_factor(pos, strongSide);
+
+ // If we don't already have an unusual scale factor, check for certain
+ // types of endgames, and use a lower scale for those.
+ if ( me->game_phase() < PHASE_MIDGAME
+ && (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN))
+ {
+ if (pos.opposite_bishops())
+ {
+ // Endgame with opposite-colored bishops and no other pieces (ignoring pawns)
+ // is almost a draw, in case of KBP vs KB is even more a draw.
+ if ( pos.non_pawn_material(WHITE) == BishopValueMg
+ && pos.non_pawn_material(BLACK) == BishopValueMg)
+ sf = more_than_one(pos.pieces(PAWN)) ? ScaleFactor(31) : ScaleFactor(9);
+
+ // Endgame with opposite-colored bishops, but also other pieces. Still
+ // a bit drawish, but not as drawish as with only the two bishops.
+ else
+ sf = ScaleFactor(46 * sf / SCALE_FACTOR_NORMAL);
+ }
+ // Endings where weaker side can place his king in front of the opponent's
+ // pawns are drawish.
+ else if ( abs(eg_value(score)) <= BishopValueEg
+ && ei.pi->pawn_span(strongSide) <= 1
+ && !pos.pawn_passed(~strongSide, pos.square<KING>(~strongSide)))
+ sf = ei.pi->pawn_span(strongSide) ? ScaleFactor(51) : ScaleFactor(37);
}
- std::string Tracing::do_trace(const Position& pos) {
+ // Interpolate between a middlegame and a (scaled by 'sf') endgame score
+ Value v = mg_value(score) * int(me->game_phase())
+ + eg_value(score) * int(PHASE_MIDGAME - me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
- Search::RootColor = pos.side_to_move();
+ v /= int(PHASE_MIDGAME);
- stream.str("");
- stream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
- memset(scores, 0, 2 * (TOTAL + 1) * sizeof(Score));
+ // In case of tracing add all single evaluation terms
+ if (DoTrace)
+ {
+ Trace::add(MATERIAL, pos.psq_score());
+ Trace::add(IMBALANCE, me->imbalance());
+ Trace::add(PAWN, ei.pi->pawns_score());
+ Trace::add(MOBILITY, mobility[WHITE] * Weights[Mobility]
+ , mobility[BLACK] * Weights[Mobility]);
+ Trace::add(SPACE, evaluate_space<WHITE>(pos, ei) * Weights[Space]
+ , evaluate_space<BLACK>(pos, ei) * Weights[Space]);
+ Trace::add(TOTAL, score);
+ }
- Value margin;
- do_evaluate<true>(pos, margin);
+ return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
+}
+
+// Explicit template instantiations
+template Value Eval::evaluate<true >(const Position&);
+template Value Eval::evaluate<false>(const Position&);
+
+
+/// 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. Useful for debugging.
+
+std::string Eval::trace(const Position& pos) {
+
+ std::memset(scores, 0, sizeof(scores));
+
+ Value v = evaluate<true>(pos);
+ v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
+
+ 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"
+ << " Material | " << Term(MATERIAL)
+ << " Imbalance | " << Term(IMBALANCE)
+ << " Pawns | " << Term(PAWN)
+ << " Knights | " << Term(KNIGHT)
+ << " Bishop | " << Term(BISHOP)
+ << " Rooks | " << Term(ROOK)
+ << " Queens | " << Term(QUEEN)
+ << " Mobility | " << Term(MOBILITY)
+ << " King safety | " << Term(KING)
+ << " Threats | " << Term(THREAT)
+ << " Passed pawns | " << Term(PASSED)
+ << " Space | " << Term(SPACE)
+ << "----------------+-------------+-------------+-------------\n"
+ << " Total | " << Term(TOTAL);
+
+ ss << "\nTotal Evaluation: " << to_cp(v) << " (white side)\n";
+
+ return ss.str();
+}
- 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";
+/// init() computes evaluation weights, usually at startup
- 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);
+void Eval::init() {
- stream << "---------------------+-------------+-------------+---------------\n";
- row("Total", TOTAL);
- stream << totals;
+ const int MaxSlope = 8700;
+ const int Peak = 1280000;
+ int t = 0;
- return stream.str();
+ for (int i = 0; i < 400; ++i)
+ {
+ t = std::min(Peak, std::min(i * i * 27, t + MaxSlope));
+ KingDanger[i] = make_score(t / 1000, 0) * Weights[KingSafety];
}
}
projects / stockfish / blobdiff