/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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/>.
*/
-
-////
-//// Includes
-////
-
+#include <algorithm>
#include <cassert>
-#include <cstring>
+#include <cstring> // For std::memset
+#include <iomanip>
+#include <sstream>
-#include "bitcount.h"
+#include "bitboard.h"
#include "evaluate.h"
#include "material.h"
#include "pawns.h"
-#include "scale.h"
-#include "thread.h"
-#include "ucioption.h"
+namespace {
-////
-//// Local definitions
-////
+ namespace Trace {
-namespace {
+ enum Term { // The first 8 entries are for PieceType
+ MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
+ };
- const int Sign[2] = { 1, -1 };
-
- // Evaluation grain size, must be a power of 2
- const int GrainSize = 8;
-
- // Evaluation weights, initialized from UCI options
- int WeightMobilityMidgame, WeightMobilityEndgame;
- int WeightPawnStructureMidgame, WeightPawnStructureEndgame;
- int WeightPassedPawnsMidgame, WeightPassedPawnsEndgame;
- int WeightKingSafety[2];
- int WeightSpace;
-
- // 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 int WeightMobilityMidgameInternal = 248;
- const int WeightMobilityEndgameInternal = 271;
- const int WeightPawnStructureMidgameInternal = 233;
- const int WeightPawnStructureEndgameInternal = 201;
- const int WeightPassedPawnsMidgameInternal = 252;
- const int WeightPassedPawnsEndgameInternal = 259;
- const int WeightKingSafetyInternal = 247;
- const int WeightKingOppSafetyInternal = 259;
- const int WeightSpaceInternal = 46;
-
- // Mobility and outposts bonus modified by Joona Kiiski
- //
- // Visually better to define tables constants
- typedef Value V;
-
- // Knight mobility bonus in middle game and endgame, indexed by the number
- // of attacked squares not occupied by friendly piecess.
- const Value MidgameKnightMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7 8
- V(-38), V(-25),V(-12), V(0), V(12), V(25), V(31), V(38), V(38)
- };
+ double scores[TERM_NB][COLOR_NB][PHASE_NB];
- const Value EndgameKnightMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7 8
- V(-33), V(-23),V(-13), V(-3), V(7), V(17), V(22), V(27), V(27)
- };
+ double to_cp(Value v) { return double(v) / PawnValueEg; }
- // Bishop mobility bonus in middle game and endgame, indexed by the number
- // of attacked squares not occupied by friendly pieces. X-ray attacks through
- // queens are also included.
- const Value MidgameBishopMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7
- V(-25), V(-11), V(3), V(17), V(31), V(45), V(57), V(65),
- // 8 9 10 11 12 13 14 15
- V( 71), V( 74), V(76), V(78), V(79), V(80), V(81), V(81)
- };
+ 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));
+ }
- const Value EndgameBishopMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7
- V(-30), V(-16), V(-2), V(12), V(26), V(40), V(52), V(60),
- // 8 9 10 11 12 13 14 15
- V( 65), V( 69), V(71), V(73), V(74), V(75), V(76), V(76)
- };
+ void add(int idx, Score w, Score b = SCORE_ZERO) {
+ add(idx, WHITE, w); add(idx, BLACK, b);
+ }
- // Rook mobility bonus in middle game and endgame, indexed by the number
- // of attacked squares not occupied by friendly pieces. X-ray attacks through
- // queens and rooks are also included.
- const Value MidgameRookMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7
- V(-20), V(-14), V(-8), V(-2), V(4), V(10), V(14), V(19),
- // 8 9 10 11 12 13 14 15
- V( 23), V( 26), V(27), V(28), V(29), V(30), V(31), V(32)
- };
+ std::ostream& operator<<(std::ostream& os, Term t) {
- const Value EndgameRookMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7
- V(-36), V(-19), V(-3), V(13), V(29), V(46), V(62), V(79),
- // 8 9 10 11 12 13 14 15
- V( 95), V(106),V(111),V(114),V(116),V(117),V(118),V(118)
- };
+ 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] << " | ";
- // Queen mobility bonus in middle game and endgame, indexed by the number
- // of attacked squares not occupied by friendly pieces.
- const Value MidgameQueenMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7
- V(-10), V(-8), V(-6), V(-3), V(-1), V( 1), V( 3), V( 5),
- // 8 9 10 11 12 13 14 15
- V( 8), V(10), V(12), V(15), V(16), V(17), V(18), V(20),
- // 16 17 18 19 20 21 22 23
- V( 20), V(20), V(20), V(20), V(20), V(20), V(20), V(20),
- // 24 25 26 27 28 29 30 31
- V( 20), V(20), V(20), V(20), V(20), V(20), V(20), V(20)
- };
+ os << std::setw(5) << scores[t][WHITE][MG] - scores[t][BLACK][MG] << " "
+ << std::setw(5) << scores[t][WHITE][EG] - scores[t][BLACK][EG] << " \n";
- const Value EndgameQueenMobilityBonus[] = {
- // 0 1 2 3 4 5 6 7
- V(-18),V(-13), V(-7), V(-2), V( 3), V (8), V(13), V(19),
- // 8 9 10 11 12 13 14 15
- V( 23), V(27), V(32), V(34), V(35), V(35), V(35), V(35),
- // 16 17 18 19 20 21 22 23
- V( 35), V(35), V(35), V(35), V(35), V(35), V(35), V(35),
- // 24 25 26 27 28 29 30 31
- V( 35), V(35), V(35), V(35), V(35), V(35), V(35), V(35)
- };
+ return os;
+ }
+ }
- // Outpost bonuses for knights and bishops, indexed by square (from white's
- // point of view).
- const Value KnightOutpostBonus[64] = {
- // A B C D E F G H
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
- V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
- V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
- V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
- V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
+ using namespace Trace;
+
+ // Struct EvalInfo contains various information computed and collected
+ // by the evaluation functions.
+ struct EvalInfo {
+
+ // attackedBy[color][piece type] is a bitboard representing all squares
+ // 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
+ // by the king safety evaluation. This consists of the squares directly
+ // adjacent to the king, and the three (or two, for a king on an edge file)
+ // squares two ranks in front of the king. For instance, if black's king
+ // is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
+ // f7, g7, h7, f6, g6 and h6.
+ Bitboard kingRing[COLOR_NB];
+
+ // kingAttackersCount[color] is the number of pieces of the given color
+ // which attack a square in the kingRing of the enemy king.
+ int kingAttackersCount[COLOR_NB];
+
+ // kingAttackersWeight[color] is the sum of the "weights" 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 elements in the
+ // KingAttackWeights array.
+ int kingAttackersWeight[COLOR_NB];
+
+ // 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];
+
+ Bitboard pinnedPieces[COLOR_NB];
+ Material::Entry* me;
+ Pawns::Entry* pi;
};
- const Value BishopOutpostBonus[64] = {
- // A B C D E F G H
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
- V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
- V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
- V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
- V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
+ #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 in the MobilityArea.
+ const Score MobilityBonus[][32] = {
+ {}, {},
+ { S(-75,-76), S(-56,-54), S(- 9,-26), S( -2,-10), S( 6, 5), S( 15, 11), // Knights
+ S( 22, 26), S( 30, 28), S( 36, 29) },
+ { S(-48,-58), S(-21,-19), S( 16, -2), S( 26, 12), S( 37, 22), S( 51, 42), // Bishops
+ S( 54, 54), S( 63, 58), S( 65, 63), S( 71, 70), S( 79, 74), S( 81, 86),
+ S( 92, 90), S( 97, 94) },
+ { S(-56,-78), S(-25,-18), S(-11, 26), S( -5, 55), S( -4, 70), S( -1, 81), // Rooks
+ S( 8,109), S( 14,120), S( 21,128), S( 23,143), S( 31,154), S( 32,160),
+ S( 43,165), S( 49,168), S( 59,169) },
+ { S(-40,-35), S(-25,-12), S( 2, 7), S( 4, 19), S( 14, 37), S( 24, 55), // Queens
+ S( 25, 62), S( 40, 76), S( 43, 79), S( 47, 87), S( 54, 94), S( 56,102),
+ S( 60,111), S( 70,116), S( 72,118), S( 73,122), S( 75,128), S( 77,130),
+ S( 85,133), S( 94,136), S( 99,140), S(108,157), S(112,158), S(113,161),
+ S(118,174), S(119,177), S(123,191), S(128,199) }
};
- // Bonus for unstoppable passed pawns
- const Value UnstoppablePawnValue = Value(0x500);
+ // 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(43,11), S(65,20) }, // Knights
+ { S(20, 3), S(29, 8) } // Bishops
+ };
- // Rooks and queens on the 7th rank (modified by Joona Kiiski)
- const Value MidgameRookOn7thBonus = Value(47);
- const Value EndgameRookOn7thBonus = Value(98);
- const Value MidgameQueenOn7thBonus = Value(27);
- const Value EndgameQueenOn7thBonus = Value(54);
+ // ReachableOutpost[knight/bishop][supported by pawn] contains bonuses for
+ // knights and bishops which can reach an outpost square in one move, bigger
+ // if outpost square is supported by a pawn.
+ const Score ReachableOutpost[][2] = {
+ { S(21, 5), S(35, 8) }, // Knights
+ { S( 8, 0), S(14, 4) } // Bishops
+ };
- // Rooks on open files (modified by Joona Kiiski)
- const Value RookOpenFileBonus = Value(43);
- const Value RookHalfOpenFileBonus = Value(19);
+ // RookOnFile[semiopen/open] contains bonuses for each rook when there is no
+ // friendly pawn on the rook file.
+ const Score RookOnFile[2] = { S(20, 7), S(45, 20) };
+
+ // ThreatBySafePawn[PieceType] contains bonuses according to which piece
+ // type is attacked by a pawn which is protected or is not attacked.
+ const Score ThreatBySafePawn[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 0), S(176, 139), S(131, 127), S(217, 218), S(203, 215) };
+
+ // Threat[by minor/by 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[][PIECE_TYPE_NB] = {
+ { S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72,107), S(48,118) }, // by Minor
+ { S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48) } // by Rook
+ };
- // Penalty for rooks trapped inside a friendly king which has lost the
- // right to castle.
- const Value TrappedRookPenalty = Value(180);
+ // ThreatByKing[on one/on many] contains bonuses for King attacks on
+ // pawns or pieces which are not pawn-defended.
+ const Score ThreatByKing[2] = { S(3, 62), S(9, 138) };
- // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
- // enemy pawns.
- const Value TrappedBishopA7H7Penalty = Value(300);
+ // 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(5), V( 5), V(31), V(73), V(166), V(252) },
+ { V(7), V(14), V(38), V(73), V(166), V(252) }
+ };
- // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
- const Bitboard MaskA7H7[2] = {
- ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
- ((1ULL << SQ_A2) | (1ULL << SQ_H2))
+ // PassedFile[File] contains a bonus according to the file of a passed pawn
+ const Score PassedFile[FILE_NB] = {
+ S( 9, 10), S( 2, 10), S( 1, -8), S(-20,-12),
+ S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
};
+ // Assorted bonuses and penalties used by evaluation
+ const Score MinorBehindPawn = S(16, 0);
+ const Score BishopPawns = S( 8, 12);
+ const Score RookOnPawn = S( 8, 24);
+ const Score TrappedRook = S(92, 0);
+ const Score SafeCheck = S(20, 20);
+ const Score OtherCheck = S(10, 10);
+ const Score ThreatByHangingPawn = S(71, 61);
+ const Score LooseEnemies = S( 0, 25);
+ const Score WeakQueen = S(35, 0);
+ const Score Hanging = S(48, 27);
+ const Score ThreatByPawnPush = S(38, 22);
+ const Score Unstoppable = S( 0, 20);
+
// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
// happen in Chess960 games.
- const Value TrappedBishopA1H1Penalty = Value(100);
+ const Score TrappedBishopA1H1 = S(50, 50);
- // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
- const Bitboard MaskA1H1[2] = {
- ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
- ((1ULL << SQ_A8) | (1ULL << SQ_H8))
- };
+ #undef S
+ #undef V
- // 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
- // based on how many squares inside this area are safe and available for
- // friendly minor pieces.
- const Bitboard SpaceMask[2] = {
- (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 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];
- /// King safety constants and variables. The king safety scores are taken
- /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
- /// the strength of the attack are added up into an integer, which is used
- /// as an index to SafetyTable[].
-
- // Attack weights for each piece type
- const int QueenAttackWeight = 5;
- const int RookAttackWeight = 3;
- const int BishopAttackWeight = 2;
- const int KnightAttackWeight = 2;
-
- // Bonuses for safe checks, initialized from UCI options
- int QueenContactCheckBonus, DiscoveredCheckBonus;
- int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
-
- // Scan for queen contact mates?
- const bool QueenContactMates = true;
-
- // Bonus for having a mate threat, initialized from UCI options
- int MateThreatBonus;
-
- // InitKingDanger[] contains bonuses based on the position of the defending
- // king.
- const int InitKingDanger[64] = {
- 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
- };
+ // KingAttackWeights[PieceType] contains king attack weights by piece type
+ const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 7, 5, 4, 1 };
- // SafetyTable[] contains the actual king safety scores. It is initialized
- // in init_safety().
- Value SafetyTable[100];
+ // Penalties for enemy's safe checks
+ const int QueenContactCheck = 89;
+ const int QueenCheck = 62;
+ const int RookCheck = 57;
+ const int BishopCheck = 48;
+ const int KnightCheck = 78;
- // Pawn and material hash tables, indexed by the current thread id
- PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
- MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
- // Sizes of pawn and material hash tables
- const int PawnTableSize = 16384;
- const int MaterialTableSize = 1024;
+ // eval_init() initializes king and attack bitboards for a given color
+ // adding pawn attacks. To be done at the beginning of the evaluation.
- // Function prototypes
- template<bool HasPopCnt>
- Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
+ template<Color Us>
+ void eval_init(const Position& pos, EvalInfo& ei) {
- template<Color Us, bool HasPopCnt>
- void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
- template<Color Us, bool HasPopCnt>
- void evaluate_king(const Position& pos, EvalInfo& ei);
+ 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);
- template<Color Us, bool HasPopCnt>
- void evaluate_space(const Position& pos, EvalInfo& ei);
+ // Init king safety tables only if we are going to use them
+ if (pos.non_pawn_material(Us) >= QueenValueMg)
+ {
+ ei.kingRing[Them] = b | shift_bb<Down>(b);
+ b &= ei.attackedBy[Us][PAWN];
+ ei.kingAttackersCount[Us] = popcount(b);
+ ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
+ }
+ else
+ ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
+ }
- void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
- void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
- void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
- inline Value apply_weight(Value v, int w);
- Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
- int weight_option(const std::string& opt, int weight);
- void init_safety();
-}
+ // evaluate_pieces() assigns bonuses and penalties to the pieces of a given
+ // color and type.
-////
-//// Functions
-////
+ template<bool DoTrace, Color Us = WHITE, PieceType Pt = KNIGHT>
+ Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility,
+ const Bitboard* mobilityArea) {
+ Bitboard b, bb;
+ Square s;
+ Score score = SCORE_ZERO;
-/// 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, EvalInfo& ei, int threadID) {
+ const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
+ : Rank5BB | Rank4BB | Rank3BB);
+ const Square* pl = pos.squares<Pt>(Us);
- return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
- : do_evaluate<false>(pos, ei, threadID);
-}
+ ei.attackedBy[Us][Pt] = 0;
-namespace {
+ while ((s = *pl++) != SQ_NONE)
+ {
+ // Find attacked squares, including x-ray attacks for bishops and rooks
+ 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);
-template<bool HasPopCnt>
-Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
+ if (ei.pinnedPieces[Us] & s)
+ b &= LineBB[pos.square<KING>(Us)][s];
- assert(pos.is_ok());
- assert(threadID >= 0 && threadID < THREAD_MAX);
+ ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;
- memset(&ei, 0, sizeof(EvalInfo));
+ if (b & ei.kingRing[Them])
+ {
+ ei.kingAttackersCount[Us]++;
+ ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
+ ei.kingAdjacentZoneAttacksCount[Us] += popcount(b & ei.attackedBy[Them][KING]);
+ }
- // Initialize by reading the incrementally updated scores included in the
- // position object (material + piece square tables)
- ei.mgValue = pos.mg_value();
- ei.egValue = pos.eg_value();
+ if (Pt == QUEEN)
+ b &= ~( ei.attackedBy[Them][KNIGHT]
+ | ei.attackedBy[Them][BISHOP]
+ | ei.attackedBy[Them][ROOK]);
- // Probe the material hash table
- ei.mi = MaterialTable[threadID]->get_material_info(pos);
- ei.mgValue += ei.mi->material_value();
- ei.egValue += ei.mi->material_value();
+ int mob = popcount(b & mobilityArea[Us]);
- // 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);
+ mobility[Us] += MobilityBonus[Pt][mob];
- // After get_material_info() call that modifies them
- ScaleFactor factor[2];
- factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
- factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
+ if (Pt == BISHOP || Pt == KNIGHT)
+ {
+ // Bonus for outpost squares
+ bb = OutpostRanks & ~ei.pi->pawn_attacks_span(Them);
+ if (bb & s)
+ score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & s)];
+ else
+ {
+ bb &= b & ~pos.pieces(Us);
+ if (bb)
+ score += ReachableOutpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & bb)];
+ }
- // Probe the pawn hash table
- ei.pi = PawnTable[threadID]->get_pawn_info(pos);
- ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
- ei.egValue += apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame);
-
- // Initialize king attack bitboards and king attack zones for both sides
- ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
- ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
- ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
- ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
-
- // Initialize pawn attack bitboards for both sides
- ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
- ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
- Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
- Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
- if (b1)
- ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
-
- if (b2)
- ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
-
- // Evaluate pieces
- evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
- evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
-
- // Kings. Kings are evaluated after all other pieces for both sides,
- // because we need complete attack information for all pieces when computing
- // the king safety evaluation.
- evaluate_king<WHITE, HasPopCnt>(pos, ei);
- evaluate_king<BLACK, HasPopCnt>(pos, ei);
-
- // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
- // because we need to know which side promotes first in positions where
- // both sides have an unstoppable passed pawn.
- if (ei.pi->passed_pawns())
- evaluate_passed_pawns(pos, ei);
-
- Phase phase = pos.game_phase();
-
- // Middle-game specific evaluation terms
- if (phase > PHASE_ENDGAME)
- {
- // Pawn storms in positions with opposite castling.
- if ( square_file(pos.king_square(WHITE)) >= FILE_E
- && square_file(pos.king_square(BLACK)) <= FILE_D)
+ // 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 the same color square as the 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;
+ }
+ }
- ei.mgValue += ei.pi->queenside_storm_value(WHITE)
- - ei.pi->kingside_storm_value(BLACK);
+ if (Pt == ROOK)
+ {
+ // Bonus for aligning with enemy pawns on the same rank/file
+ if (relative_rank(Us, s) >= RANK_5)
+ score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
- else if ( square_file(pos.king_square(WHITE)) <= FILE_D
- && square_file(pos.king_square(BLACK)) >= FILE_E)
+ // Bonus when on an open or semi-open file
+ if (ei.pi->semiopen_file(Us, file_of(s)))
+ score += RookOnFile[!!ei.pi->semiopen_file(Them, file_of(s))];
- ei.mgValue += ei.pi->kingside_storm_value(WHITE)
- - ei.pi->queenside_storm_value(BLACK);
+ // Penalize when trapped by the king, even more if the king cannot castle
+ else if (mob <= 3)
+ {
+ Square ksq = pos.square<KING>(Us);
- // Evaluate space for both sides
- if (ei.mi->space_weight() > 0)
- {
- evaluate_space<WHITE, HasPopCnt>(pos, ei);
- evaluate_space<BLACK, HasPopCnt>(pos, ei);
+ 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));
+ }
+ }
}
- }
- // Mobility
- ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
- ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
+ if (DoTrace)
+ Trace::add(Pt, Us, score);
- // If we don't already have an unusual scale factor, check for opposite
- // colored bishop endgames, and use a lower scale for those
- if ( phase < PHASE_MIDGAME
- && pos.opposite_colored_bishops()
- && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
- || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
- {
- ScaleFactor sf;
-
- // Only the two bishops ?
- if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
- && pos.non_pawn_material(BLACK) == BishopValueMidgame)
- {
- // 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.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 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);
-
- if (factor[WHITE] == SCALE_FACTOR_NORMAL)
- factor[WHITE] = sf;
- if (factor[BLACK] == SCALE_FACTOR_NORMAL)
- factor[BLACK] = sf;
+ // Recursively call evaluate_pieces() of next piece type until KING is excluded
+ return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility, mobilityArea);
}
- // Interpolate between the middle game and the endgame score
- Color stm = pos.side_to_move();
+ template<>
+ Score evaluate_pieces<false, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
+ template<>
+ Score evaluate_pieces< true, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
- Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
- return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
-}
+ // evaluate_king() assigns bonuses and penalties to a king of a given color
-} // namespace
+ template<Color Us, bool DoTrace>
+ Score evaluate_king(const Position& pos, const EvalInfo& ei) {
-/// quick_evaluate() does a very approximate evaluation of the current position.
-/// It currently considers only material and piece square table scores. Perhaps
-/// we should add scores from the pawn and material hash tables?
-
-Value quick_evaluate(const Position &pos) {
-
- assert(pos.is_ok());
-
- static const
- ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
-
- Value mgv = pos.mg_value();
- Value egv = pos.eg_value();
- Phase ph = pos.game_phase();
- Color stm = pos.side_to_move();
-
- return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
-}
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
+ Bitboard undefended, b, b1, b2, safe, other;
+ int attackUnits;
+ const Square ksq = pos.square<KING>(Us);
-/// init_eval() initializes various tables used by the evaluation function
+ // King shelter and enemy pawns storm
+ Score score = ei.pi->king_safety<Us>(pos, ksq);
-void init_eval(int threads) {
-
- assert(threads <= THREAD_MAX);
-
- for (int i = 0; i < THREAD_MAX; i++)
- {
- if (i >= threads)
+ // Main king safety evaluation
+ if (ei.kingAttackersCount[Them])
{
- delete PawnTable[i];
- delete MaterialTable[i];
- PawnTable[i] = NULL;
- MaterialTable[i] = NULL;
- continue;
- }
- if (!PawnTable[i])
- PawnTable[i] = new PawnInfoTable(PawnTableSize);
- if (!MaterialTable[i])
- MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
- }
-}
-
-
-/// quit_eval() releases heap-allocated memory at program termination
-
-void quit_eval() {
-
- for (int i = 0; i < THREAD_MAX; i++)
- {
- delete PawnTable[i];
- delete MaterialTable[i];
- PawnTable[i] = NULL;
- MaterialTable[i] = NULL;
- }
-}
-
+ // Find the attacked squares which are defended only by the king...
+ 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]);
+
+ // ... and those which are not defended at all in the larger king ring
+ b = ei.attackedBy[Them][ALL_PIECES] & ~ei.attackedBy[Us][ALL_PIECES]
+ & ei.kingRing[Us] & ~pos.pieces(Them);
+
+ // Initialize the 'attackUnits' variable, which is used later on as an
+ // 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 and the quality of
+ // the pawn shelter (current 'score' value).
+ attackUnits = std::min(72, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
+ + 9 * ei.kingAdjacentZoneAttacksCount[Them]
+ + 21 * popcount(undefended)
+ + 12 * (popcount(b) + !!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)
+ {
+ // ...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];
-/// read_weights() reads evaluation weights from the corresponding UCI parameters
+ attackUnits += QueenContactCheck * popcount(b);
+ }
-void read_weights(Color us) {
+ // Analyse the safe enemy's checks which are possible on next move...
+ safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
- Color them = opposite_color(us);
+ // ... and some other potential checks, only requiring the square to be
+ // safe from pawn-attacks, and not being occupied by a blocked pawn.
+ other = ~( ei.attackedBy[Us][PAWN]
+ | (pos.pieces(Them, PAWN) & shift_bb<Up>(pos.pieces(PAWN))));
- WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
- WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
- WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
- WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
- WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
- WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
- WeightSpace = weight_option("Space", WeightSpaceInternal);
- WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
- WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
+ b1 = pos.attacks_from<ROOK >(ksq);
+ b2 = pos.attacks_from<BISHOP>(ksq);
- // If running in analysis mode, make sure we use symmetrical king safety. We do this
- // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
- if (get_option_value_bool("UCI_AnalyseMode"))
- {
- WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
- WeightKingSafety[them] = WeightKingSafety[us];
- }
- init_safety();
-}
+ // Enemy queen safe checks
+ if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
+ attackUnits += QueenCheck, score -= SafeCheck;
+ // Enemy rooks safe and other checks
+ if (b1 & ei.attackedBy[Them][ROOK] & safe)
+ attackUnits += RookCheck, score -= SafeCheck;
-namespace {
+ else if (b1 & ei.attackedBy[Them][ROOK] & other)
+ score -= OtherCheck;
- // evaluate_mobility() computes mobility and attacks for every piece
+ // Enemy bishops safe and other checks
+ if (b2 & ei.attackedBy[Them][BISHOP] & safe)
+ attackUnits += BishopCheck, score -= SafeCheck;
- template<PieceType Piece, Color Us, bool HasPopCnt>
- int evaluate_mobility(const Position& pos, Bitboard b, EvalInfo& ei) {
+ else if (b2 & ei.attackedBy[Them][BISHOP] & other)
+ score -= OtherCheck;
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
- static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
- static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
- static const int lastIndex[] = { 0, 0, 8, 15, 15, 31 };
+ // Enemy knights safe and other checks
+ b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
+ if (b & safe)
+ attackUnits += KnightCheck, score -= SafeCheck;
- // Update attack info
- ei.attackedBy[Us][Piece] |= b;
+ else if (b & other)
+ score -= OtherCheck;
- // King attacks
- if (b & ei.kingZone[Us])
- {
- ei.kingAttackersCount[Us]++;
- ei.kingAttackersWeight[Us] += AttackWeight[Piece];
- Bitboard bb = (b & ei.attackedBy[Them][KING]);
- if (bb)
- ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
+ // Finally, extract the king danger score from the KingDanger[]
+ // array and subtract the score from the evaluation.
+ score -= KingDanger[std::max(std::min(attackUnits, 399), 0)];
}
- // Remove squares protected by enemy pawns or occupied by our pieces
- b &= ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
-
- // The squares occupied by enemy pieces (not defended by pawns) will be
- // counted two times instead of one. The shift (almost) guarantees that
- // intersection of the shifted value with b is zero so that after or-ing
- // the count of 1s bits is increased by the number of affected squares.
- b |= Us == WHITE ? ((b & pos.pieces_of_color(Them)) >> 1)
- : ((b & pos.pieces_of_color(Them)) << 1);
+ if (DoTrace)
+ Trace::add(KING, Us, score);
- // Mobility
- int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b)
- : count_1s<HasPopCnt>(b));
-
- if (mob > lastIndex[Piece])
- mob = lastIndex[Piece];
-
- ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
- ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
- return mob;
+ return score;
}
- // evaluate_outposts() evaluates bishop and knight outposts squares
-
- template<PieceType Piece, Color Us>
- void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
+ // evaluate_threats() assigns bonuses according to the types of the attacking
+ // and the attacked pieces.
- const Color Them = (Us == WHITE ? BLACK : WHITE);
-
- // Initial bonus based on square
- Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
- : KnightOutpostBonus[relative_square(Us, s)]);
+ template<Color Us, bool DoTrace>
+ Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
- // Increase bonus if supported by pawn, especially if the opponent has
- // no minor piece which can exchange the outpost piece
- if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
- {
- if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
- && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
- bonus += bonus + bonus / 2;
- else
- bonus += bonus / 2;
- }
- ei.mgValue += Sign[Us] * bonus;
- ei.egValue += Sign[Us] * bonus;
- }
+ 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);
+ enum { Minor, Rook };
- // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
+ Bitboard b, weak, defended, safeThreats;
+ Score score = SCORE_ZERO;
- template<PieceType Piece, Color Us, bool HasPopCnt>
- void evaluate_pieces(const Position& pos, EvalInfo& ei) {
+ // Small bonus if the opponent has loose pawns or pieces
+ if ( (pos.pieces(Them) ^ pos.pieces(Them, QUEEN, KING))
+ & ~(ei.attackedBy[Us][ALL_PIECES] | ei.attackedBy[Them][ALL_PIECES]))
+ score += LooseEnemies;
- Bitboard b;
- Square s, ksq;
- int mob;
- File f;
+ // Bonus for pin or discovered attack on the opponent queen
+ if ( pos.count<QUEEN>(Them) == 1
+ && pos.slider_blockers(pos.pieces(),
+ pos.pieces(Us, ROOK, BISHOP),
+ pos.square<QUEEN>(Them)))
+ score += WeakQueen;
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square* ptr = pos.piece_list_begin(Us, Piece);
+ // Non-pawn enemies attacked by a pawn
+ weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];
- while ((s = *ptr++) != SQ_NONE)
+ if (weak)
{
- if (Piece == KNIGHT || Piece == QUEEN)
- b = pos.attacks_from<Piece>(s);
- else if (Piece == BISHOP)
- b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
- else if (Piece == ROOK)
- b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
- else
- assert(false);
-
- // Attacks and mobility
- mob = evaluate_mobility<Piece, Us, HasPopCnt>(pos, b, ei);
-
- // Bishop and knight outposts squares
- if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
- evaluate_outposts<Piece, Us>(pos, ei, s);
-
- // Special patterns: trapped bishops on a7/h7/a2/h2
- // and trapped bishops on a1/h1/a8/h8 in Chess960.
- if (Piece == BISHOP)
- {
- if (bit_is_set(MaskA7H7[Us], s))
- evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
+ b = pos.pieces(Us, PAWN) & ( ~ei.attackedBy[Them][ALL_PIECES]
+ | ei.attackedBy[Us][ALL_PIECES]);
- if (Chess960 && bit_is_set(MaskA1H1[Us], s))
- evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
- }
+ safeThreats = (shift_bb<Right>(b) | shift_bb<Left>(b)) & weak;
- if (Piece == ROOK || Piece == QUEEN)
- {
- // Queen or rook on 7th rank
- if ( relative_rank(Us, s) == RANK_7
- && relative_rank(Us, pos.king_square(Them)) == RANK_8)
- {
- ei.mgValue += Sign[Us] * (Piece == ROOK ? MidgameRookOn7thBonus : MidgameQueenOn7thBonus);
- ei.egValue += Sign[Us] * (Piece == ROOK ? EndgameRookOn7thBonus : EndgameQueenOn7thBonus);
- }
- }
-
- // Special extra evaluation for rooks
- if (Piece == ROOK)
- {
- // Open and half-open files
- f = square_file(s);
- if (ei.pi->file_is_half_open(Us, f))
- {
- if (ei.pi->file_is_half_open(Them, f))
- {
- ei.mgValue += Sign[Us] * RookOpenFileBonus;
- ei.egValue += Sign[Us] * RookOpenFileBonus;
- }
- else
- {
- ei.mgValue += Sign[Us] * RookHalfOpenFileBonus;
- ei.egValue += Sign[Us] * RookHalfOpenFileBonus;
- }
- }
+ if (weak ^ safeThreats)
+ score += ThreatByHangingPawn;
- // Penalize rooks which are trapped inside a king. Penalize more if
- // king has lost right to castle.
- if (mob > 6 || ei.pi->file_is_half_open(Us, f))
- continue;
-
- ksq = pos.king_square(Us);
-
- if ( square_file(ksq) >= FILE_E
- && square_file(s) > square_file(ksq)
- && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
- {
- // Is there a half-open file between the king and the edge of the board?
- if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
- ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
- : Sign[Us] * (TrappedRookPenalty - mob * 16);
- }
- else if ( square_file(ksq) <= FILE_D
- && square_file(s) < square_file(ksq)
- && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
- {
- // Is there a half-open file between the king and the edge of the board?
- if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
- ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
- : Sign[Us] * (TrappedRookPenalty - mob * 16);
- }
- }
+ while (safeThreats)
+ score += ThreatBySafePawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
}
- }
+ // Non-pawn enemies defended by a pawn
+ defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Them][PAWN];
- // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
- // pieces of a given color.
+ // Enemies not defended by a pawn and under our attack
+ weak = pos.pieces(Them)
+ & ~ei.attackedBy[Them][PAWN]
+ & ei.attackedBy[Us][ALL_PIECES];
- template<Color Us, bool HasPopCnt>
- void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
+ // Add a bonus according to the kind of attacking pieces
+ if (defended | weak)
+ {
+ b = (defended | weak) & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+ while (b)
+ score += Threat[Minor][type_of(pos.piece_on(pop_lsb(&b)))];
- evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
- evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
- evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
- evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
+ b = (pos.pieces(Them, QUEEN) | weak) & ei.attackedBy[Us][ROOK];
+ while (b)
+ score += Threat[Rook ][type_of(pos.piece_on(pop_lsb(&b)))];
- // Sum up all attacked squares
- ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
- | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
- | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
- }
+ score += Hanging * popcount(weak & ~ei.attackedBy[Them][ALL_PIECES]);
+ b = weak & ei.attackedBy[Us][KING];
+ if (b)
+ score += ThreatByKing[more_than_one(b)];
+ }
- // evaluate_king<>() assigns bonuses and penalties to a king of a given color
+ // 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()));
- template<Color Us, bool HasPopCnt>
- void evaluate_king(const Position& pos, EvalInfo& ei) {
+ b &= ~pos.pieces()
+ & ~ei.attackedBy[Them][PAWN]
+ & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square s = pos.king_square(Us);
- int shelter = 0;
+ b = (shift_bb<Left>(b) | shift_bb<Right>(b))
+ & pos.pieces(Them)
+ & ~ei.attackedBy[Us][PAWN];
- // King shelter
- if (relative_rank(Us, s) <= RANK_4)
- {
- shelter = ei.pi->get_king_shelter(pos, Us, s);
- ei.mgValue += Sign[Us] * Value(shelter);
- }
+ score += ThreatByPawnPush * popcount(b);
- // King safety. This is quite complicated, and is almost certainly far
- // from optimally tuned.
- if ( pos.piece_count(Them, QUEEN) >= 1
- && ei.kingAttackersCount[Them] >= 2
- && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
- && ei.kingAdjacentZoneAttacksCount[Them])
- {
- // Is it the attackers turn to move?
- bool sente = (Them == pos.side_to_move());
-
- // Find the attacked squares around the king which has no defenders
- // apart from the king itself
- Bitboard undefended =
- ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
- & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
- & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
- & ei.attacked_by(Us, KING);
-
- Bitboard occ = pos.occupied_squares(), b, b2;
-
- // Initialize the 'attackUnits' variable, which is used later on as an
- // index to the SafetyTable[] array. The initial value is based on the
- // number and types of the attacking pieces, the number of attacked and
- // undefended squares around the king, the square of the king, and the
- // quality of the pawn shelter.
- int attackUnits =
- Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
- + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
- + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
-
- // Analyse safe queen contact checks
- b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
- if (b)
- {
- Bitboard attackedByOthers =
- ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
- | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
-
- b &= attackedByOthers;
- if (b)
- {
- // The bitboard b now contains the squares available for safe queen
- // contact checks.
- int count = count_1s_max_15<HasPopCnt>(b);
- attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
-
- // Is there a mate threat?
- if (QueenContactMates && !pos.is_check())
- {
- Bitboard escapeSquares =
- pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
-
- while (b)
- {
- Square from, to = pop_1st_bit(&b);
- if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
- {
- // We have a mate, unless the queen is pinned or there
- // is an X-ray attack through the queen.
- for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
- {
- from = pos.piece_list(Them, QUEEN, i);
- if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
- && !bit_is_set(pos.pinned_pieces(Them), from)
- && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
- && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
-
- ei.mateThreat[Them] = make_move(from, to);
- }
- }
- }
- }
- }
- }
-
- // Analyse safe distance checks
- if (QueenCheckBonus > 0 || RookCheckBonus > 0)
- {
- b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
-
- // Queen checks
- b2 = b & ei.attacked_by(Them, QUEEN);
- if (b2)
- attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
-
- // Rook checks
- b2 = b & ei.attacked_by(Them, ROOK);
- if (b2)
- attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
- }
- if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
- {
- b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
-
- // Queen checks
- b2 = b & ei.attacked_by(Them, QUEEN);
- if (b2)
- attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
-
- // Bishop checks
- b2 = b & ei.attacked_by(Them, BISHOP);
- if (b2)
- attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
- }
- if (KnightCheckBonus > 0)
- {
- b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
-
- // Knight checks
- b2 = b & ei.attacked_by(Them, KNIGHT);
- if (b2)
- attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
- }
-
- // Analyse discovered checks (only for non-pawns right now, consider
- // adding pawns later).
- if (DiscoveredCheckBonus)
- {
- b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
- if (b)
- attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
- }
-
- // Has a mate threat been found? We don't do anything here if the
- // side with the mating move is the side to move, because in that
- // case the mating side will get a huge bonus at the end of the main
- // evaluation function instead.
- if (ei.mateThreat[Them] != MOVE_NONE)
- attackUnits += MateThreatBonus;
-
- // Ensure that attackUnits is between 0 and 99, in order to avoid array
- // out of bounds errors:
- if (attackUnits < 0)
- attackUnits = 0;
-
- if (attackUnits >= 100)
- attackUnits = 99;
-
- // Finally, extract the king safety score from the SafetyTable[] array.
- // Add the score to the evaluation, and also to ei.futilityMargin. The
- // reason for adding the king safety score to the futility margin is
- // that the king safety scores can sometimes be very big, and that
- // capturing a single attacking piece can therefore result in a score
- // change far bigger than the value of the captured piece.
- Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
-
- ei.mgValue -= Sign[Us] * v;
-
- if (Us == pos.side_to_move())
- ei.futilityMargin += v;
- }
+ if (DoTrace)
+ Trace::add(THREAT, Us, score);
+
+ return score;
}
// evaluate_passed_pawns() evaluates the passed pawns of the given color
- template<Color Us>
- void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], EvalInfo& ei) {
+ template<Color Us, bool DoTrace>
+ Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
- Bitboard b2, b3, b4;
- Square ourKingSq = pos.king_square(Us);
- Square theirKingSq = pos.king_square(Them);
- Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
+ Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
+ Score score = SCORE_ZERO;
+
+ b = ei.pi->passed_pawns(Us);
while (b)
{
- Square s = pop_1st_bit(&b);
+ Square s = pop_lsb(&b);
- assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
- assert(pos.pawn_is_passed(Us, s));
+ assert(pos.pawn_passed(Us, s));
- int r = int(relative_rank(Us, s) - RANK_2);
- int tr = Max(0, r * (r - 1));
+ int r = relative_rank(Us, s) - RANK_2;
+ int rr = r * (r - 1);
- // Base bonus based on rank
- Value mbonus = Value(20 * tr);
- Value ebonus = Value(10 + r * r * 10);
+ Value mbonus = Passed[MG][r], ebonus = Passed[EG][r];
- // Adjust bonus based on king proximity
- if (tr)
+ if (rr)
{
Square blockSq = s + pawn_push(Us);
- ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
- ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
- ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
-
- // If the pawn is free to advance, increase bonus
- if (pos.square_is_empty(blockSq))
- {
- // There are no enemy pawns in the pawn's path
- b2 = squares_in_front_of(Us, s);
-
- assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
-
- // Squares attacked by us
- b4 = b2 & ei.attacked_by(Us);
-
- // Squares attacked or occupied by enemy pieces
- b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
-
- // If there is an enemy rook or queen attacking the pawn from behind,
- // add all X-ray attacks by the rook or queen.
- if ( bit_is_set(ei.attacked_by(Them, ROOK) | ei.attacked_by(Them, QUEEN), s)
- && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them)))
- b3 = b2;
-
- // Are any of the squares in the pawn's path attacked or occupied by the enemy?
- if (b3 == EmptyBoardBB)
- // No enemy attacks or pieces, huge bonus!
- // Even bigger if we protect the pawn's path
- ebonus += Value(tr * (b2 == b4 ? 17 : 15));
- else
- // OK, there are enemy attacks or pieces (but not pawns). Are those
- // squares which are attacked by the enemy also attacked by us ?
- // If yes, big bonus (but smaller than when there are no enemy attacks),
- // if no, somewhat smaller bonus.
- ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
-
- // At last, add a small bonus when there are no *friendly* pieces
- // in the pawn's path.
- if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
- ebonus += Value(tr);
- }
- } // tr != 0
-
- // If the pawn is supported by a friendly pawn, increase bonus
- b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
- if (b2 & rank_bb(s))
- ebonus += Value(r * 20);
- else if (pos.attacks_from<PAWN>(s, Them) & b2)
- ebonus += Value(r * 12);
-
- // If the other side has only a king, check whether the pawn is
- // unstoppable
- if (pos.non_pawn_material(Them) == Value(0))
- {
- Square qsq;
- int d;
+ // 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;
- qsq = relative_square(Us, make_square(square_file(s), RANK_8));
- d = square_distance(s, qsq)
- - square_distance(theirKingSq, qsq)
- + (Us != pos.side_to_move());
+ // 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 (d < 0)
+ // If the pawn is free to advance, then increase the bonus
+ if (pos.empty(blockSq))
{
- int mtg = RANK_8 - relative_rank(Us, s);
- int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
- mtg += blockerCount;
- d += blockerCount;
- if (d < 0)
- movesToGo[Us] = movesToGo[Us] ? Min(movesToGo[Us], mtg) : mtg;
- }
- }
-
- // 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 (square_file(s) == FILE_A || square_file(s) == FILE_H)
- {
- if ( pos.non_pawn_material(Them) <= KnightValueMidgame
- && pos.piece_count(Them, KNIGHT) <= 1)
- ebonus += ebonus / 4;
- else if (pos.pieces(ROOK, QUEEN, Them))
- ebonus -= ebonus / 4;
- }
+ // 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);
- // Add the scores for this pawn to the middle game and endgame eval.
- ei.mgValue += apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame);
- ei.egValue += apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame);
+ Bitboard bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
- } // while
- }
+ if (!(pos.pieces(Us) & bb))
+ defendedSquares &= ei.attackedBy[Us][ALL_PIECES];
+ if (!(pos.pieces(Them) & bb))
+ unsafeSquares &= ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
- // evaluate_passed_pawns() evaluates the passed pawns for both sides
+ // 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;
- void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
+ // If the path to the queen is fully defended, assign a big bonus.
+ // Otherwise assign a smaller bonus if the block square is defended.
+ if (defendedSquares == squaresToQueen)
+ k += 6;
- int movesToGo[2] = {0, 0};
+ else if (defendedSquares & blockSq)
+ k += 4;
- // Evaluate pawns for each color
- evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, ei);
- evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, ei);
+ mbonus += k * rr, ebonus += k * rr;
+ }
+ else if (pos.pieces(Us) & blockSq)
+ mbonus += rr + r * 2, ebonus += rr + r * 2;
+ } // rr != 0
- // Does either side have an unstoppable passed pawn?
- if (movesToGo[WHITE] && !movesToGo[BLACK])
- ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]);
- else if (movesToGo[BLACK] && !movesToGo[WHITE])
- ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]);
- else if (movesToGo[BLACK] && movesToGo[WHITE])
- {
- // Both sides have unstoppable pawns! Try to find out who queens
- // first. We begin by transforming 'movesToGo' to the number of
- // plies until the pawn queens for both sides.
- movesToGo[WHITE] *= 2;
- movesToGo[BLACK] *= 2;
- movesToGo[pos.side_to_move()]--;
-
- // If one side queens at least three plies before the other, that
- // side wins.
- if (movesToGo[WHITE] <= movesToGo[BLACK] - 3)
- ei.egValue += UnstoppablePawnValue - Value(0x40 * (movesToGo[WHITE]/2));
- else if (movesToGo[BLACK] <= movesToGo[WHITE] - 3)
- ei.egValue -= UnstoppablePawnValue - Value(0x40 * (movesToGo[BLACK]/2));
-
- // We could also add some rules about the situation when one side
- // queens exactly one ply before the other: Does the first queen
- // check the opponent's king, or attack the opponent's queening square?
- // This is slightly tricky to get right, because it is possible that
- // the opponent's king has moved somewhere before the first pawn queens.
+ score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
}
+
+ if (DoTrace)
+ Trace::add(PASSED, Us, score);
+
+ // Add the scores to the middlegame and endgame eval
+ return score;
}
- // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
- // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
- // if it is.
+ // 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 multiplied by a weight. The aim is to
+ // improve play on game opening.
+ template<Color Us>
+ Score evaluate_space(const Position& pos, const EvalInfo& ei) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Bitboard SpaceMask =
+ Us == WHITE ? (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB)
+ : (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB);
+
+ // 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
+ & ~pos.pieces(Us, PAWN)
+ & ~ei.attackedBy[Them][PAWN]
+ & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
- void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
+ // 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);
- assert(square_is_ok(s));
- assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
+ // Since SpaceMask[Us] is fully on our half of the board...
+ assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
- Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
- Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
+ // ...count safe + (behind & safe) with a single popcount
+ int bonus = popcount((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);
- if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
- && pos.see(s, b6) < 0
- && pos.see(s, b8) < 0)
- {
- ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
- ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
- }
+ return make_score(bonus * weight * weight * 2 / 11, 0);
}
- // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
- // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
- // black), and assigns a penalty if it is. This pattern can obviously
- // only occur in Chess960 games.
+ // 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, int asymmetry, Value eg) {
- void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
+ int kingDistance = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
+ - distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
+ int pawns = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK);
- Piece pawn = piece_of_color_and_type(us, PAWN);
- Square b2, b3, c3;
+ // Compute the initiative bonus for the attacking side
+ int initiative = 8 * (asymmetry + kingDistance - 15) + 12 * pawns;
- assert(Chess960);
- assert(square_is_ok(s));
- assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
+ // Now apply the bonus: note that we find the attacking side by extracting
+ // the sign of the endgame value, and that we carefully cap the bonus so
+ // that the endgame score will never be divided by more than two.
+ int value = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg / 2));
- if (square_file(s) == FILE_A)
- {
- b2 = relative_square(us, SQ_B2);
- b3 = relative_square(us, SQ_B3);
- c3 = relative_square(us, SQ_C3);
- }
- else
- {
- b2 = relative_square(us, SQ_G2);
- b3 = relative_square(us, SQ_G3);
- c3 = relative_square(us, SQ_F3);
- }
+ return make_score(0, value);
+ }
- if (pos.piece_on(b2) == pawn)
- {
- Value penalty;
- if (!pos.square_is_empty(b3))
- penalty = 2*TrappedBishopA1H1Penalty;
- else if (pos.piece_on(c3) == pawn)
- penalty = TrappedBishopA1H1Penalty;
- else
- penalty = TrappedBishopA1H1Penalty / 2;
+ // evaluate_scale_factor() computes the scale factor for the winning side
+ ScaleFactor evaluate_scale_factor(const Position& pos, const EvalInfo& ei, Value eg) {
+
+ Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
+ ScaleFactor sf = ei.me->scale_factor(pos, strongSide);
- ei.mgValue -= Sign[us] * penalty;
- ei.egValue -= Sign[us] * penalty;
+ // If we don't already have an unusual scale factor, check for certain
+ // types of endgames, and use a lower scale for those.
+ if ( ei.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, it 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) <= 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);
}
+
+ return sf;
}
+} // namespace
- // 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.
- template<Color Us, bool HasPopCnt>
- void evaluate_space(const Position& pos, EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+/// evaluate() is the main evaluation function. It returns a static evaluation
+/// of the position from the point of view of the side to move.
- // Find the safe squares for our pieces inside the area defined by
- // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
- // pawn, or if it is undefended and attacked by an enemy piece.
+template<bool DoTrace>
+Value Eval::evaluate(const Position& pos) {
- Bitboard safeSquares = SpaceMask[Us]
- & ~pos.pieces(PAWN, Us)
- & ~ei.attacked_by(Them, PAWN)
- & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
+ assert(!pos.checkers());
- // Find all squares which are at most three squares behind some friendly
- // pawn.
- Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
- behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
- behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
+ EvalInfo ei;
+ Score score, mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
- int space = count_1s_max_15<HasPopCnt>(safeSquares)
- + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
+ // Initialize score by reading the incrementally updated scores included in
+ // the position object (material + piece square tables). Score is computed
+ // internally from the white point of view.
+ score = pos.psq_score();
- ei.mgValue += Sign[Us] * apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
- }
+ // Probe the material hash table
+ ei.me = Material::probe(pos);
+ score += ei.me->imbalance();
+ // If we have a specialized evaluation function for the current material
+ // configuration, call it and return.
+ if (ei.me->specialized_eval_exists())
+ return ei.me->evaluate(pos);
- // apply_weight() applies an evaluation weight to a value
+ // Probe the pawn hash table
+ ei.pi = Pawns::probe(pos);
+ score += ei.pi->pawns_score();
+
+ // Initialize attack and king safety bitboards
+ ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
+ eval_init<WHITE>(pos, ei);
+ eval_init<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)
+ };
- inline Value apply_weight(Value v, int w) {
- return (v*w) / 0x100;
- }
+ // Do not include in mobility area 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 all pieces but king and pawns
+ score += evaluate_pieces<DoTrace>(pos, ei, mobility, mobilityArea);
+ score += mobility[WHITE] - mobility[BLACK];
- // scale_by_game_phase() interpolates between a middle game and an endgame
- // score, based on game phase. It also scales the return value by a
- // ScaleFactor array.
+ // Evaluate kings after all other pieces because we need full attack
+ // information when computing the king safety evaluation.
+ score += evaluate_king<WHITE, DoTrace>(pos, ei)
+ - evaluate_king<BLACK, DoTrace>(pos, ei);
- Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
+ // Evaluate tactical threats, we need full attack information including king
+ score += evaluate_threats<WHITE, DoTrace>(pos, ei)
+ - evaluate_threats<BLACK, DoTrace>(pos, ei);
- assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
- assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
- assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
+ // 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);
- ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
+ // 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 += Unstoppable * int(relative_rank(WHITE, frontmost_sq(WHITE, b)));
- Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
- return Value(int(result) & ~(GrainSize - 1));
+ if ((b = ei.pi->passed_pawns(BLACK)) != 0)
+ score -= Unstoppable * int(relative_rank(BLACK, frontmost_sq(BLACK, b)));
}
+ // 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);
- // weight_option() computes the value of an evaluation weight, by combining
- // an UCI-configurable weight with an internal weight.
+ // Evaluate position potential for the winning side
+ score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
- int weight_option(const std::string& opt, int internalWeight) {
+ // Evaluate scale factor for the winning side
+ ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
- int uciWeight = get_option_value_int(opt);
- uciWeight = (uciWeight * 0x100) / 100;
- return (uciWeight * internalWeight) / 0x100;
- }
+ // Interpolate between a middlegame and a (scaled by 'sf') endgame score
+ Value v = mg_value(score) * int(ei.me->game_phase())
+ + eg_value(score) * int(PHASE_MIDGAME - ei.me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
+
+ v /= int(PHASE_MIDGAME);
+ // In case of tracing add all remaining individual evaluation terms
+ if (DoTrace)
+ {
+ Trace::add(MATERIAL, pos.psq_score());
+ Trace::add(IMBALANCE, ei.me->imbalance());
+ Trace::add(PAWN, ei.pi->pawns_score());
+ Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
+ Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)
+ , evaluate_space<BLACK>(pos, ei));
+ Trace::add(TOTAL, score);
+ }
- // init_safety() initizes the king safety evaluation, based on UCI
- // parameters. It is called from read_weights().
+ return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
+}
- void init_safety() {
+// 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();
+}
- QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
- QueenCheckBonus = get_option_value_int("Queen Check Bonus");
- RookCheckBonus = get_option_value_int("Rook Check Bonus");
- BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
- KnightCheckBonus = get_option_value_int("Knight Check Bonus");
- DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
- MateThreatBonus = get_option_value_int("Mate Threat Bonus");
- int maxSlope = get_option_value_int("King Safety Max Slope");
- int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
- double a = get_option_value_int("King Safety Coefficient") / 100.0;
- double b = get_option_value_int("King Safety X Intercept");
- bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
- bool linear = (get_option_value_string("King Safety Curve") == "Linear");
+/// init() computes evaluation weights, usually at startup
- for (int i = 0; i < 100; i++)
- {
- if (i < b)
- SafetyTable[i] = Value(0);
- else if (quad)
- SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
- else if (linear)
- SafetyTable[i] = Value((int)(100 * a * (i - b)));
- }
+void Eval::init() {
- for (int i = 0; i < 100; i++)
- {
- if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
- for (int j = i + 1; j < 100; j++)
- SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
+ const int MaxSlope = 322;
+ const int Peak = 47410;
+ int t = 0;
- if (SafetyTable[i] > Value(peak))
- SafetyTable[i] = Value(peak);
- }
+ for (int i = 0; i < 400; ++i)
+ {
+ t = std::min(Peak, std::min(i * i - 16, t + MaxSlope));
+ KingDanger[i] = make_score(t * 268 / 7700, 0);
}
}
projects / stockfish / blobdiff