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921 lines
36 KiB
C++
921 lines
36 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <algorithm>
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#include <cassert>
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#include <iomanip>
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#include <sstream>
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#include "bitcount.h"
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#include "evaluate.h"
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#include "material.h"
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#include "pawns.h"
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#include "thread.h"
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#include "ucioption.h"
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namespace {
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// Struct EvalInfo contains various information computed and collected
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// by the evaluation functions.
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struct EvalInfo {
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// Pointers to material and pawn hash table entries
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Material::Entry* mi;
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Pawns::Entry* pi;
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// attackedBy[color][piece type] is a bitboard representing all squares
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// attacked by a given color and piece type, attackedBy[color][ALL_PIECES]
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// contains all squares attacked by the given color.
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Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
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// kingRing[color] is the zone around the king which is considered
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// by the king safety evaluation. This consists of the squares directly
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// adjacent to the king, and the three (or two, for a king on an edge file)
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// squares two ranks in front of the king. For instance, if black's king
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// is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
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// f7, g7, h7, f6, g6 and h6.
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Bitboard kingRing[COLOR_NB];
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// kingAttackersCount[color] is the number of pieces of the given color
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// which attack a square in the kingRing of the enemy king.
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int kingAttackersCount[COLOR_NB];
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// kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
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// given color which attack a square in the kingRing of the enemy king. The
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// weights of the individual piece types are given by the variables
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// QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
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// KnightAttackWeight in evaluate.cpp
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int kingAttackersWeight[COLOR_NB];
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// kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
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// directly adjacent to the king of the given color. Pieces which attack
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// more than one square are counted multiple times. For instance, if black's
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// king is on g8 and there's a white knight on g5, this knight adds
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// 2 to kingAdjacentZoneAttacksCount[BLACK].
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int kingAdjacentZoneAttacksCount[COLOR_NB];
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Bitboard pinnedPieces[COLOR_NB];
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};
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namespace Tracing {
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enum Terms { // First 8 entries are for PieceType
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PST = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERMS_NB
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};
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Score terms[COLOR_NB][TERMS_NB];
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EvalInfo ei;
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ScaleFactor sf;
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double to_cp(Value v);
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void add_term(int idx, Score term_w, Score term_b = SCORE_ZERO);
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void format_row(std::stringstream& ss, const char* name, int idx);
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std::string do_trace(const Position& pos);
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}
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// Evaluation weights, initialized from UCI options
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enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
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struct Weight { int mg, eg; } Weights[6];
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typedef Value V;
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#define S(mg, eg) make_score(mg, eg)
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// Internal evaluation weights. These are applied on top of the evaluation
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// weights read from UCI parameters. The purpose is to be able to change
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// the evaluation weights while keeping the default values of the UCI
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// parameters at 100, which looks prettier.
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//
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// Values modified by Joona Kiiski
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const Score WeightsInternal[] = {
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S(289, 344), S(233, 201), S(221, 273), S(46, 0), S(271, 0), S(307, 0)
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};
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// MobilityBonus[PieceType][attacked] contains bonuses for middle and end
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// game, indexed by piece type and number of attacked squares not occupied by
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// friendly pieces.
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const Score MobilityBonus[][32] = {
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{}, {},
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{ S(-65,-50), S(-42,-30), S(-9,-10), S( 3, 0), S(15, 10), S(27, 20), // Knights
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S( 37, 28), S( 42, 31), S(44, 33) },
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{ S(-52,-47), S(-28,-23), S( 6, 1), S(20, 15), S(34, 29), S(48, 43), // Bishops
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S( 60, 55), S( 68, 63), S(74, 68), S(77, 72), S(80, 75), S(82, 77),
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S( 84, 79), S( 86, 81) },
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{ S(-47,-53), S(-31,-26), S(-5, 0), S( 1, 16), S( 7, 32), S(13, 48), // Rooks
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S( 18, 64), S( 22, 80), S(26, 96), S(29,109), S(31,115), S(33,119),
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S( 35,122), S( 36,123), S(37,124) },
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{ S(-42,-40), S(-28,-23), S(-5, -7), S( 0, 0), S( 6, 10), S(11, 19), // Queens
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S( 13, 29), S( 18, 38), S(20, 40), S(21, 41), S(22, 41), S(22, 41),
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S( 22, 41), S( 23, 41), S(24, 41), S(25, 41), S(25, 41), S(25, 41),
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S( 25, 41), S( 25, 41), S(25, 41), S(25, 41), S(25, 41), S(25, 41),
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S( 25, 41), S( 25, 41), S(25, 41), S(25, 41) }
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};
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// Outpost[PieceType][Square] contains bonuses for knights and bishops outposts,
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// indexed by piece type and square (from white's point of view).
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const Value Outpost[][SQUARE_NB] = {
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{// A B C D E F G H
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
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V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
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V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
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V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
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V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },
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{
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
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V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
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V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
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V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
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V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }
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};
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// Threat[attacking][attacked] contains bonuses according to which piece
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// type attacks which one.
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const Score Threat[][PIECE_TYPE_NB] = {
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{ S(0, 0), S( 7, 39), S(24, 49), S(24, 49), S(41,100), S(41,100) }, // Minor
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{ S(0, 0), S(15, 39), S(15, 45), S(15, 45), S(15, 45), S(24, 49) } // Major
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};
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// ThreatenedByPawn[PieceType] contains a penalty according to which piece
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// type is attacked by an enemy pawn.
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const Score ThreatenedByPawn[] = {
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S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
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};
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// Hanging[side to move] contains a bonus for each enemy hanging piece
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const Score Hanging[2] = { S(23, 20) , S(35, 45) };
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#undef S
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const Score Tempo = make_score(24, 11);
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const Score RookOnPawn = make_score(10, 28);
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const Score RookOpenFile = make_score(43, 21);
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const Score RookSemiopenFile = make_score(19, 10);
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const Score BishopPawns = make_score( 8, 12);
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const Score MinorBehindPawn = make_score(16, 0);
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const Score TrappedRook = make_score(90, 0);
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const Score Unstoppable = make_score( 0, 20);
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// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
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// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
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// happen in Chess960 games.
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const Score TrappedBishopA1H1 = make_score(50, 50);
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// SpaceMask[Color] contains the area of the board which is considered
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// by the space evaluation. In the middlegame, each side is given a bonus
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// based on how many squares inside this area are safe and available for
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// friendly minor pieces.
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const Bitboard SpaceMask[] = {
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(FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB),
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(FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB)
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};
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// King danger constants and variables. The king danger scores are taken
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// from KingDanger[]. Various little "meta-bonuses" measuring the strength
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// of the enemy attack are added up into an integer, which is used as an
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// index to KingDanger[].
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//
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// KingAttackWeights[PieceType] contains king attack weights by piece type
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const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
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// Bonuses for enemy's safe checks
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const int QueenContactCheck = 24;
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const int RookContactCheck = 16;
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const int QueenCheck = 12;
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const int RookCheck = 8;
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const int BishopCheck = 2;
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const int KnightCheck = 3;
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// KingDanger[Color][attackUnits] contains the actual king danger weighted
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// scores, indexed by color and by a calculated integer number.
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Score KingDanger[COLOR_NB][128];
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// apply_weight() weighs score 'v' by weight 'w' trying to prevent overflow
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Score apply_weight(Score v, const Weight& w) {
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return make_score(mg_value(v) * w.mg / 256, eg_value(v) * w.eg / 256);
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}
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// weight_option() computes the value of an evaluation weight, by combining
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// two UCI-configurable weights (midgame and endgame) with an internal weight.
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Weight weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
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Weight w = { Options[mgOpt] * mg_value(internalWeight) / 100,
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Options[egOpt] * eg_value(internalWeight) / 100 };
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return w;
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}
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// init_eval_info() initializes king bitboards for given color adding
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// pawn attacks. To be done at the beginning of the evaluation.
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template<Color Us>
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void init_eval_info(const Position& pos, EvalInfo& ei) {
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const Color Them = (Us == WHITE ? BLACK : WHITE);
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const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
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ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
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Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
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ei.attackedBy[Us][ALL_PIECES] = ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
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// Init king safety tables only if we are going to use them
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if (pos.count<QUEEN>(Us) && pos.non_pawn_material(Us) > QueenValueMg + PawnValueMg)
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{
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ei.kingRing[Them] = b | shift_bb<Down>(b);
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b &= ei.attackedBy[Us][PAWN];
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ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) : 0;
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ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
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}
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else
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ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
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}
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// evaluate_outposts() evaluates bishop and knight outpost squares
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template<PieceType Pt, Color Us>
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Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
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const Color Them = (Us == WHITE ? BLACK : WHITE);
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assert (Pt == BISHOP || Pt == KNIGHT);
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// Initial bonus based on square
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Value bonus = Outpost[Pt == BISHOP][relative_square(Us, s)];
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// Increase bonus if supported by pawn, especially if the opponent has
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// no minor piece which can trade with the outpost piece.
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if (bonus && (ei.attackedBy[Us][PAWN] & s))
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{
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if ( !pos.pieces(Them, KNIGHT)
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&& !(squares_of_color(s) & pos.pieces(Them, BISHOP)))
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bonus += bonus + bonus / 2;
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else
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bonus += bonus / 2;
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}
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return make_score(bonus, bonus);
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}
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// evaluate_pieces() assigns bonuses and penalties to the pieces of a given color
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template<PieceType Pt, Color Us, bool Trace>
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Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility, Bitboard* mobilityArea) {
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Bitboard b;
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Square s;
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Score score = SCORE_ZERO;
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const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
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const Color Them = (Us == WHITE ? BLACK : WHITE);
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const Square* pl = pos.list<Pt>(Us);
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ei.attackedBy[Us][Pt] = 0;
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while ((s = *pl++) != SQ_NONE)
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{
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// Find attacked squares, including x-ray attacks for bishops and rooks
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b = Pt == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN))
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: Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
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: pos.attacks_from<Pt>(s);
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if (ei.pinnedPieces[Us] & s)
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b &= LineBB[pos.king_square(Us)][s];
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ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;
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if (b & ei.kingRing[Them])
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{
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ei.kingAttackersCount[Us]++;
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ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
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Bitboard bb = b & ei.attackedBy[Them][KING];
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if (bb)
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ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
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}
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if (Pt == QUEEN)
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b &= ~( ei.attackedBy[Them][KNIGHT]
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| ei.attackedBy[Them][BISHOP]
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| ei.attackedBy[Them][ROOK]);
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int mob = Pt != QUEEN ? popcount<Max15>(b & mobilityArea[Us])
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: popcount<Full >(b & mobilityArea[Us]);
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mobility[Us] += MobilityBonus[Pt][mob];
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// Decrease score if we are attacked by an enemy pawn. The remaining part
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// of threat evaluation must be done later when we have full attack info.
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if (ei.attackedBy[Them][PAWN] & s)
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score -= ThreatenedByPawn[Pt];
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if (Pt == BISHOP || Pt == KNIGHT)
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{
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// Penalty for bishop with same colored pawns
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if (Pt == BISHOP)
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score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
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// Bishop and knight outposts squares
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if (!(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
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score += evaluate_outposts<Pt, Us>(pos, ei, s);
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// Bishop or knight behind a pawn
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if ( relative_rank(Us, s) < RANK_5
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&& (pos.pieces(PAWN) & (s + pawn_push(Us))))
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score += MinorBehindPawn;
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}
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if (Pt == ROOK)
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{
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// Rook piece attacking enemy pawns on the same rank/file
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if (relative_rank(Us, s) >= RANK_5)
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{
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Bitboard pawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
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if (pawns)
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score += popcount<Max15>(pawns) * RookOnPawn;
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}
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// Give a bonus for a rook on a open or semi-open file
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if (ei.pi->semiopen_file(Us, file_of(s)))
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score += ei.pi->semiopen_file(Them, file_of(s)) ? RookOpenFile : RookSemiopenFile;
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if (mob > 3 || ei.pi->semiopen_file(Us, file_of(s)))
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continue;
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Square ksq = pos.king_square(Us);
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// Penalize rooks which are trapped by a king. Penalize more if the
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// king has lost its castling capability.
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if ( ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
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&& (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
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&& !ei.pi->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
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score -= (TrappedRook - make_score(mob * 8, 0)) * (1 + !pos.can_castle(Us));
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}
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// An important Chess960 pattern: A cornered bishop blocked by a friendly
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// pawn diagonally in front of it is a very serious problem, especially
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// when that pawn is also blocked.
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if ( Pt == BISHOP
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&& pos.is_chess960()
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&& (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
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{
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Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
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if (pos.piece_on(s + d) == make_piece(Us, PAWN))
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score -= !pos.empty(s + d + pawn_push(Us)) ? TrappedBishopA1H1 * 4
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: pos.piece_on(s + d + d) == make_piece(Us, PAWN) ? TrappedBishopA1H1 * 2
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: TrappedBishopA1H1;
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}
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}
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if (Trace)
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Tracing::terms[Us][Pt] = score;
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return score - evaluate_pieces<NextPt, Them, Trace>(pos, ei, mobility, mobilityArea);
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}
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template<>
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Score evaluate_pieces<KING, WHITE, false>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
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template<>
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Score evaluate_pieces<KING, WHITE, true>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
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// evaluate_king() assigns bonuses and penalties to a king of a given color
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template<Color Us, bool Trace>
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Score evaluate_king(const Position& pos, const EvalInfo& ei) {
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const Color Them = (Us == WHITE ? BLACK : WHITE);
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Bitboard undefended, b, b1, b2, safe;
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int attackUnits;
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const Square ksq = pos.king_square(Us);
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// King shelter and enemy pawns storm
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Score score = ei.pi->king_safety<Us>(pos, ksq);
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// Main king safety evaluation
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if (ei.kingAttackersCount[Them])
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{
|
|
// 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]
|
|
& ~( 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 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))
|
|
+ 2 * (ei.pinnedPieces[Us] != 0)
|
|
- mg_value(score) / 32;
|
|
|
|
// 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)
|
|
{
|
|
// ...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 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's rook gives check
|
|
b &= PseudoAttacks[ROOK][ksq];
|
|
|
|
if (b)
|
|
{
|
|
// ...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 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;
|
|
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);
|
|
|
|
// Enemy rooks safe checks
|
|
b = b1 & ei.attackedBy[Them][ROOK];
|
|
if (b)
|
|
attackUnits += RookCheck * popcount<Max15>(b);
|
|
|
|
// Enemy bishops safe checks
|
|
b = b2 & ei.attackedBy[Them][BISHOP];
|
|
if (b)
|
|
attackUnits += BishopCheck * popcount<Max15>(b);
|
|
|
|
// 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));
|
|
|
|
// Finally, extract the king danger score from the KingDanger[]
|
|
// array and subtract the score from evaluation.
|
|
score -= KingDanger[Us == Search::RootColor][attackUnits];
|
|
}
|
|
|
|
if (Trace)
|
|
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, weakEnemies;
|
|
Score score = SCORE_ZERO;
|
|
|
|
// 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
|
|
|
|
template<Color Us, bool Trace>
|
|
Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
|
|
Score score = SCORE_ZERO;
|
|
|
|
b = ei.pi->passed_pawns(Us);
|
|
|
|
while (b)
|
|
{
|
|
Square s = pop_lsb(&b);
|
|
|
|
assert(pos.pawn_passed(Us, s));
|
|
|
|
int r = relative_rank(Us, s) - RANK_2;
|
|
int rr = r * (r - 1);
|
|
|
|
// Base bonus based on rank
|
|
Value mbonus = Value(17 * rr), ebonus = Value(7 * (rr + r + 1));
|
|
|
|
if (rr)
|
|
{
|
|
Square blockSq = s + pawn_push(Us);
|
|
|
|
// 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 (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, then increase the bonus
|
|
if (pos.empty(blockSq))
|
|
{
|
|
squaresToQueen = forward_bb(Us, s);
|
|
|
|
// 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 ( unlikely(forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN))
|
|
&& (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 ( 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;
|
|
|
|
// 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 += 4;
|
|
|
|
mbonus += k * rr, ebonus += k * rr;
|
|
}
|
|
} // rr != 0
|
|
|
|
if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
|
|
ebonus += ebonus / 4;
|
|
|
|
score += make_score(mbonus, ebonus);
|
|
}
|
|
|
|
if (Trace)
|
|
Tracing::terms[Us][Tracing::PASSED] = apply_weight(score, Weights[PassedPawns]);
|
|
|
|
// Add the scores to the middlegame and endgame eval
|
|
return apply_weight(score, Weights[PassedPawns]);
|
|
}
|
|
|
|
|
|
// 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, Color us, const EvalInfo& ei) {
|
|
|
|
Bitboard b = ei.pi->passed_pawns(us) | ei.pi->candidate_pawns(us);
|
|
|
|
if (!b || pos.non_pawn_material(~us))
|
|
return SCORE_ZERO;
|
|
|
|
return Unstoppable * int(relative_rank(us, frontmost_sq(us, b)));
|
|
}
|
|
|
|
|
|
// 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) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
// 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]);
|
|
|
|
// 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);
|
|
|
|
// 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));
|
|
}
|
|
|
|
|
|
// do_evaluate() is the evaluation entry point, called directly from evaluate()
|
|
|
|
template<bool Trace>
|
|
Value do_evaluate(const Position& pos) {
|
|
|
|
assert(!pos.checkers());
|
|
|
|
EvalInfo ei;
|
|
Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
|
|
Thread* thisThread = pos.this_thread();
|
|
|
|
// 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);
|
|
|
|
// Probe the material hash table
|
|
ei.mi = Material::probe(pos, thisThread->materialTable, thisThread->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())
|
|
return ei.mi->evaluate(pos);
|
|
|
|
// Probe the pawn hash table
|
|
ei.pi = Pawns::probe(pos, thisThread->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);
|
|
|
|
ei.attackedBy[WHITE][ALL_PIECES] |= ei.attackedBy[WHITE][KING];
|
|
ei.attackedBy[BLACK][ALL_PIECES] |= ei.attackedBy[BLACK][KING];
|
|
|
|
// 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)) };
|
|
|
|
// Evaluate pieces and mobility
|
|
score += evaluate_pieces<KNIGHT, WHITE, Trace>(pos, ei, mobility, mobilityArea);
|
|
score += apply_weight(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, Trace>(pos, ei)
|
|
- evaluate_king<BLACK, Trace>(pos, ei);
|
|
|
|
// 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, 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);
|
|
|
|
// Evaluate space for both sides, only in middlegame
|
|
if (ei.mi->space_weight())
|
|
{
|
|
int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
|
|
score += apply_weight(s * ei.mi->space_weight(), Weights[Space]);
|
|
}
|
|
|
|
// Scale winning side if position is more drawish than 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 || 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);
|
|
}
|
|
|
|
// 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;
|
|
|
|
v /= int(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;
|
|
}
|
|
|
|
return pos.side_to_move() == WHITE ? v : -v;
|
|
}
|
|
|
|
|
|
// Tracing function definitions
|
|
|
|
double Tracing::to_cp(Value v) { return double(v) / PawnValueEg; }
|
|
|
|
void Tracing::add_term(int idx, Score wScore, Score bScore) {
|
|
|
|
terms[WHITE][idx] = wScore;
|
|
terms[BLACK][idx] = bScore;
|
|
}
|
|
|
|
void Tracing::format_row(std::stringstream& ss, const char* name, int idx) {
|
|
|
|
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) {
|
|
|
|
std::memset(terms, 0, sizeof(terms));
|
|
|
|
Value v = do_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";
|
|
|
|
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);
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format_row(ss, "Rooks", ROOK);
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format_row(ss, "Queens", QUEEN);
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|
format_row(ss, "Mobility", MOBILITY);
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|
format_row(ss, "King safety", KING);
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|
format_row(ss, "Threats", THREAT);
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|
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";
|
|
|
|
return ss.str();
|
|
}
|
|
|
|
} // namespace
|
|
|
|
|
|
namespace Eval {
|
|
|
|
/// 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);
|
|
}
|
|
|
|
|
|
/// 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);
|
|
}
|
|
|
|
|
|
/// 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 double MaxSlope = 30;
|
|
const double Peak = 1280;
|
|
|
|
for (int t = 0, i = 1; i < 100; ++i)
|
|
{
|
|
t = int(std::min(Peak, std::min(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
|