Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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
#include <iomanip>
#include <sstream>
-#include "bitcount.h"
+#include "bitboard.h"
#include "evaluate.h"
#include "material.h"
#include "pawns.h"
namespace {
+ namespace Trace {
+
+ enum Term { // The first 8 entries are for PieceType
+ MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
+ };
+
+ double scores[TERM_NB][COLOR_NB][PHASE_NB];
+
+ double to_cp(Value v) { return double(v) / PawnValueEg; }
+
+ void add(int idx, Color c, Score s) {
+ scores[idx][c][MG] = to_cp(mg_value(s));
+ scores[idx][c][EG] = to_cp(eg_value(s));
+ }
+
+ void add(int idx, Score w, Score b = SCORE_ZERO) {
+ add(idx, WHITE, w); add(idx, BLACK, b);
+ }
+
+ std::ostream& operator<<(std::ostream& os, Term t) {
+
+ if (t == MATERIAL || t == IMBALANCE || t == Term(PAWN) || t == TOTAL)
+ os << " --- --- | --- --- | ";
+ else
+ os << std::setw(5) << scores[t][WHITE][MG] << " "
+ << std::setw(5) << scores[t][WHITE][EG] << " | "
+ << std::setw(5) << scores[t][BLACK][MG] << " "
+ << std::setw(5) << scores[t][BLACK][EG] << " | ";
+
+ os << std::setw(5) << scores[t][WHITE][MG] - scores[t][BLACK][MG] << " "
+ << std::setw(5) << scores[t][WHITE][EG] - scores[t][BLACK][EG] << " \n";
+
+ return os;
+ }
+ }
+
+ using namespace Trace;
+
// Struct EvalInfo contains various information computed and collected
// by the evaluation functions.
struct EvalInfo {
- // Pointers to material and pawn hash table entries
- Material::Entry* mi;
- Pawns::Entry* pi;
-
// attackedBy[color][piece type] is a bitboard representing all squares
- // attacked by a given color and piece type, attackedBy[color][ALL_PIECES]
- // contains all squares attacked by the given color.
+ // attacked by a given color and piece type (can be also ALL_PIECES).
Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
+ // attackedBy2[color] are the squares attacked by 2 pieces of a given color,
+ // possibly via x-ray or by one pawn and one piece. Diagonal x-ray through
+ // pawn or squares attacked by 2 pawns are not explicitly added.
+ Bitboard attackedBy2[COLOR_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)
// which attack a square in the kingRing of the enemy king.
int kingAttackersCount[COLOR_NB];
- // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
+ // 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 to squares
- // directly adjacent to the king of the given color. Pieces which attack
- // more than one square are counted multiple times. For instance, if black's
- // king is on g8 and there's a white knight on g5, this knight adds
- // 2 to kingAdjacentZoneAttacksCount[BLACK].
+ // kingAdjacentZoneAttacksCount[color] is the number of attacks by the given
+ // color to squares directly adjacent to the enemy king. Pieces which attack
+ // more than one square are counted multiple times. For instance, if there is
+ // a white knight on g5 and black's king is on g8, this white knight adds 2
+ // to kingAdjacentZoneAttacksCount[WHITE].
int kingAdjacentZoneAttacksCount[COLOR_NB];
Bitboard pinnedPieces[COLOR_NB];
- };
-
- namespace Tracing {
-
- enum Terms { // First 8 entries are for PieceType
- MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERMS_NB
- };
-
- Score scores[COLOR_NB][TERMS_NB];
- EvalInfo ei;
- ScaleFactor sf;
-
- double to_cp(Value v);
- void write(int idx, Color c, Score s);
- void write(int idx, Score w, Score b = SCORE_ZERO);
- void print(std::stringstream& ss, const char* name, int idx);
- std::string do_trace(const Position& pos);
- }
-
- // Evaluation weights, indexed by evaluation term
- enum { Mobility, PawnStructure, PassedPawns, Space, KingSafety };
- const struct Weight { int mg, eg; } Weights[] = {
- {289, 344}, {233, 201}, {221, 273}, {46, 0}, {322, 0}
+ Material::Entry* me;
+ Pawns::Entry* pi;
};
#define V(v) Value(v)
#define S(mg, eg) make_score(mg, eg)
// MobilityBonus[PieceType][attacked] contains bonuses for middle and end
- // game, indexed by piece type and number of attacked squares not occupied by
- // friendly pieces.
+ // game, indexed by piece type and number of attacked squares in the MobilityArea.
const Score MobilityBonus[][32] = {
{}, {},
- { S(-65,-50), S(-42,-30), S(-9,-10), S( 3, 0), S(15, 10), S(27, 20), // Knights
- S( 37, 28), S( 42, 31), S(44, 33) },
- { S(-52,-47), S(-28,-23), S( 6, 1), S(20, 15), S(34, 29), S(48, 43), // Bishops
- S( 60, 55), S( 68, 63), S(74, 68), S(77, 72), S(80, 75), S(82, 77),
- S( 84, 79), S( 86, 81) },
- { S(-47,-53), S(-31,-26), S(-5, 0), S( 1, 16), S( 7, 32), S(13, 48), // Rooks
- S( 18, 64), S( 22, 80), S(26, 96), S(29,109), S(31,115), S(33,119),
- S( 35,122), S( 36,123), S(37,124) },
- { S(-42,-40), S(-28,-23), S(-5, -7), S( 0, 0), S( 6, 10), S(11, 19), // Queens
- S( 13, 29), S( 18, 38), S(20, 40), S(21, 41), S(22, 41), S(22, 41),
- S( 22, 41), S( 23, 41), S(24, 41), S(25, 41), S(25, 41), S(25, 41),
- S( 25, 41), S( 25, 41), S(25, 41), S(25, 41), S(25, 41), S(25, 41),
- S( 25, 41), S( 25, 41), S(25, 41), S(25, 41) }
+ { 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) }
};
- // Outpost[PieceType][Square] contains bonuses for knights and bishops outposts,
- // indexed by piece type and square (from white's point of view).
- const Value Outpost[][SQUARE_NB] = {
- {// A B C D E F G H
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
- V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
- V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
- V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
- V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },
- {
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
- V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
- V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
- V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
- V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
- V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }
+ // Outpost[knight/bishop][supported by pawn] contains bonuses for knights and
+ // bishops outposts, bigger if outpost piece is supported by a pawn.
+ const Score Outpost[][2] = {
+ { S(43,11), S(65,20) }, // Knights
+ { S(20, 3), S(29, 8) } // Bishops
+ };
+
+ // 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
};
- // Threat[defended/weak][minor/major attacking][attacked PieceType] contains
+ // 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.
- const Score Threat[][2][PIECE_TYPE_NB] = {
- { { S(0, 0), S( 0, 0), S(19, 37), S(24, 37), S(44, 97), S(35,106) }, // Defended Minor
- { S(0, 0), S( 0, 0), S( 9, 14), S( 9, 14), S( 7, 14), S(24, 48) } }, // Defended Major
- { { S(0, 0), S( 0,32), S(33, 41), S(31, 50), S(41,100), S(35,104) }, // Weak Minor
- { S(0, 0), S( 0,27), S(26, 57), S(26, 57), S(0 , 43), S(23, 51) } } // Weak Major
+ // 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
};
- // ThreatenedByPawn[PieceType] contains a penalty according to which piece
- // type is attacked by an enemy pawn.
- const Score ThreatenedByPawn[] = {
- S(0, 0), S(0, 0), S(87, 118), S(84, 122), S(114, 203), S(121, 217)
+ // 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) };
+
+ // 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) }
+ };
+
+ // 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 KingOnOne = S( 2, 58);
- const Score KingOnMany = S( 6,125);
- const Score RookOnPawn = S( 7, 27);
- const Score RookOnOpenFile = S(43, 21);
- const Score RookOnSemiOpenFile = S(19, 10);
- const Score BishopPawns = S( 8, 12);
- const Score MinorBehindPawn = S(16, 0);
- const Score TrappedRook = S(92, 0);
- const Score Unstoppable = S( 0, 20);
- const Score Hanging = S(31, 26);
- const Score PawnAttackThreat = S(20, 20);
+ const Score MinorBehindPawn = S(16, 0);
+ const Score BishopPawns = S( 8, 12);
+ const Score RookOnPawn = S( 8, 24);
+ const Score TrappedRook = S(92, 0);
+ const Score CloseEnemies = S( 7, 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
#undef S
#undef V
- // SpaceMask[Color] contains the area of the board which is considered
- // by the space evaluation. In the middlegame, each side is given a bonus
- // based on how many squares inside this area are safe and available for
- // friendly minor pieces.
- const Bitboard SpaceMask[] = {
- (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB),
- (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB)
- };
-
// 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];
+
// KingAttackWeights[PieceType] contains king attack weights by piece type
- const int KingAttackWeights[] = { 0, 0, 7, 5, 4, 1 };
+ const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 7, 5, 4, 1 };
- // Bonuses for enemy's safe checks
+ // Penalties for enemy's safe checks
const int QueenContactCheck = 89;
- const int RookContactCheck = 71;
- const int QueenCheck = 50;
- const int RookCheck = 37;
- const int BishopCheck = 6;
- const int KnightCheck = 14;
-
- // KingDanger[attackUnits] contains the actual king danger weighted
- // scores, indexed by a calculated integer number.
- Score KingDanger[512];
+ const int QueenCheck = 62;
+ const int RookCheck = 57;
+ const int BishopCheck = 48;
+ const int KnightCheck = 78;
- // apply_weight() weighs score 's' by weight 'w' trying to prevent overflow
- Score apply_weight(Score s, const Weight& w) {
- return make_score(mg_value(s) * w.mg / 256, eg_value(s) * w.eg / 256);
- }
-
- // init_eval_info() initializes king bitboards for given color adding
- // pawn attacks. To be done at the beginning of the evaluation.
+ // eval_init() initializes king and attack bitboards for a given color
+ // adding pawn attacks. To be done at the beginning of the evaluation.
template<Color Us>
- void init_eval_info(const Position& pos, EvalInfo& ei) {
+ void eval_init(const Position& pos, EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
-
- Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
- ei.attackedBy[Us][ALL_PIECES] = ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
+ Bitboard b = ei.attackedBy[Them][KING];
+ ei.attackedBy[Them][ALL_PIECES] |= b;
+ ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
+ ei.attackedBy2[Us] = ei.attackedBy[Us][PAWN] & ei.attackedBy[Us][KING];
// 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] = b ? popcount<Max15>(b) : 0;
+ ei.kingAttackersCount[Us] = popcount(b);
ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
}
else
}
- // evaluate_outpost() evaluates bishop and knight outpost squares
-
- template<PieceType Pt, Color Us>
- Score evaluate_outpost(const Position& pos, const EvalInfo& ei, Square s) {
-
- const Color Them = (Us == WHITE ? BLACK : WHITE);
-
- assert (Pt == BISHOP || Pt == KNIGHT);
-
- // Initial bonus based on square
- Value bonus = Outpost[Pt == BISHOP][relative_square(Us, s)];
-
- // Increase bonus if supported by pawn, especially if the opponent has
- // no minor piece which can trade with the outpost piece.
- if (bonus && (ei.attackedBy[Us][PAWN] & s))
- {
- if ( !pos.pieces(Them, KNIGHT)
- && !(squares_of_color(s) & pos.pieces(Them, BISHOP)))
- bonus += bonus + bonus / 2;
- else
- bonus += bonus / 2;
- }
-
- return make_score(bonus * 2, bonus / 2);
- }
-
-
- // evaluate_pieces() assigns bonuses and penalties to the pieces of a given color
-
- template<PieceType Pt, Color Us, bool Trace>
- Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility, Bitboard* mobilityArea) {
+ // evaluate_pieces() assigns bonuses and penalties to the pieces of a given
+ // color and type.
- Bitboard b;
+ 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;
const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square* pl = pos.list<Pt>(Us);
+ const Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
+ : Rank5BB | Rank4BB | Rank3BB);
+ const Square* pl = pos.squares<Pt>(Us);
ei.attackedBy[Us][Pt] = 0;
: pos.attacks_from<Pt>(s);
if (ei.pinnedPieces[Us] & s)
- b &= LineBB[pos.king_square(Us)][s];
+ b &= LineBB[pos.square<KING>(Us)][s];
+ ei.attackedBy2[Us] |= ei.attackedBy[Us][ALL_PIECES] & b;
ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;
if (b & ei.kingRing[Them])
{
ei.kingAttackersCount[Us]++;
ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
- Bitboard bb = b & ei.attackedBy[Them][KING];
- if (bb)
- ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
+ ei.kingAdjacentZoneAttacksCount[Us] += popcount(b & ei.attackedBy[Them][KING]);
}
if (Pt == QUEEN)
| ei.attackedBy[Them][BISHOP]
| ei.attackedBy[Them][ROOK]);
- int mob = Pt != QUEEN ? popcount<Max15>(b & mobilityArea[Us])
- : popcount<Full >(b & mobilityArea[Us]);
+ int mob = popcount(b & mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt][mob];
- // Decrease score if we are attacked by an enemy pawn. The remaining part
- // of threat evaluation must be done later when we have full attack info.
- if (ei.attackedBy[Them][PAWN] & s)
- score -= ThreatenedByPawn[Pt];
-
if (Pt == BISHOP || Pt == KNIGHT)
{
- // Bonus for outpost square
- if (!(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
- score += evaluate_outpost<Pt, Us>(pos, ei, s);
+ // 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)];
+ }
// Bonus when behind a pawn
if ( relative_rank(Us, s) < RANK_5
&& (pos.pieces(PAWN) & (s + pawn_push(Us))))
score += MinorBehindPawn;
- // Penalty for pawns on same color square of bishop
+ // 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);
{
// Bonus for aligning with enemy pawns on the same rank/file
if (relative_rank(Us, s) >= RANK_5)
- {
- Bitboard alignedPawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
- if (alignedPawns)
- score += popcount<Max15>(alignedPawns) * RookOnPawn;
- }
+ score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
// Bonus when on an open or semi-open file
if (ei.pi->semiopen_file(Us, file_of(s)))
- score += ei.pi->semiopen_file(Them, file_of(s)) ? RookOnOpenFile : RookOnSemiOpenFile;
+ score += RookOnFile[!!ei.pi->semiopen_file(Them, file_of(s))];
- // Penalize when trapped by the king, even more if king cannot castle
- if (mob <= 3 && !ei.pi->semiopen_file(Us, file_of(s)))
+ // Penalize when trapped by the king, even more if the king cannot castle
+ else if (mob <= 3)
{
- Square ksq = pos.king_square(Us);
+ Square ksq = pos.square<KING>(Us);
if ( ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
&& (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
}
}
+
+ if (Pt == QUEEN)
+ {
+ // Penalty if any relative pin or discovered attack against the queen
+ if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s))
+ score -= WeakQueen;
+ }
}
- if (Trace)
- Tracing::write(Pt, Us, score);
+ if (DoTrace)
+ Trace::add(Pt, Us, score);
- // Recursively call evaluate_pieces() of next piece type until KING excluded
- return score - evaluate_pieces<NextPt, Them, Trace>(pos, ei, mobility, mobilityArea);
+ // Recursively call evaluate_pieces() of next piece type until KING is excluded
+ return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility, mobilityArea);
}
template<>
- Score evaluate_pieces<KING, WHITE, false>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
+ Score evaluate_pieces<false, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
template<>
- Score evaluate_pieces<KING, WHITE, true>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
+ Score evaluate_pieces< true, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
// evaluate_king() assigns bonuses and penalties to a king of a given color
- template<Color Us, bool Trace>
+ const Bitboard WhiteCamp = Rank1BB | Rank2BB | Rank3BB | Rank4BB | Rank5BB;
+ const Bitboard BlackCamp = Rank8BB | Rank7BB | Rank6BB | Rank5BB | Rank4BB;
+ const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
+ const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+ const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
+
+ const Bitboard KingFlank[COLOR_NB][FILE_NB] = {
+ { QueenSide & WhiteCamp, QueenSide & WhiteCamp, QueenSide & WhiteCamp, CenterFiles & WhiteCamp,
+ CenterFiles & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp },
+ { QueenSide & BlackCamp, QueenSide & BlackCamp, QueenSide & BlackCamp, CenterFiles & BlackCamp,
+ CenterFiles & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp },
+ };
+
+ template<Color Us, bool DoTrace>
Score evaluate_king(const Position& pos, const EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
- Bitboard undefended, b, b1, b2, safe;
+ Bitboard undefended, b, b1, b2, safe, other;
int attackUnits;
- const Square ksq = pos.king_square(Us);
+ const Square ksq = pos.square<KING>(Us);
// King shelter and enemy pawns storm
Score score = ei.pi->king_safety<Us>(pos, ksq);
// Main king safety evaluation
if (ei.kingAttackersCount[Them])
{
- // 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]);
+ // Find the attacked squares which are defended only by the king...
+ undefended = ei.attackedBy[Them][ALL_PIECES]
+ & ei.attackedBy[Us][KING]
+ & ~ei.attackedBy2[Us];
+
+ // ... 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(74, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
- + 8 * ei.kingAdjacentZoneAttacksCount[Them]
- + 25 * popcount<Max15>(undefended)
- + 11 * (ei.pinnedPieces[Us] != 0)
- - mg_value(score) * 31 / 256
- - !pos.count<QUEEN>(Them) * 60;
+ 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];
- if (b)
- attackUnits += QueenContactCheck * popcount<Max15>(b);
- }
+ // ...and keep squares supported by another enemy piece
+ attackUnits += QueenContactCheck * popcount(b & ei.attackedBy2[Them]);
- // Analyse the enemy's safe rook contact checks. Firstly, find the
- // undefended squares around the king reachable by the enemy rooks...
- b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
+ // Analyse the safe enemy's checks which are possible on next move...
+ safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
- // Consider only squares where the enemy's rook gives check
- b &= PseudoAttacks[ROOK][ksq];
+ // ... 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))));
- 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]);
+ b1 = pos.attacks_from<ROOK >(ksq);
+ b2 = pos.attacks_from<BISHOP>(ksq);
- if (b)
- attackUnits += RookContactCheck * popcount<Max15>(b);
- }
+ // Enemy queen safe checks
+ if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
+ attackUnits += QueenCheck, score -= SafeCheck;
- // Analyse the enemy's safe distance checks for sliders and knights
- safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
+ // For other pieces, also consider the square safe if attacked twice,
+ // and only defended by a queen.
+ safe |= ei.attackedBy2[Them]
+ & ~(ei.attackedBy2[Us] | pos.pieces(Them))
+ & ei.attackedBy[Us][QUEEN];
- b1 = pos.attacks_from<ROOK >(ksq) & safe;
- b2 = pos.attacks_from<BISHOP>(ksq) & safe;
+ // Enemy rooks safe and other checks
+ if (b1 & ei.attackedBy[Them][ROOK] & safe)
+ attackUnits += RookCheck, score -= SafeCheck;
- // Enemy queen safe checks
- b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
- if (b)
- attackUnits += QueenCheck * popcount<Max15>(b);
+ else if (b1 & ei.attackedBy[Them][ROOK] & other)
+ score -= OtherCheck;
- // Enemy rooks safe checks
- b = b1 & ei.attackedBy[Them][ROOK];
- if (b)
- attackUnits += RookCheck * popcount<Max15>(b);
+ // Enemy bishops safe and other checks
+ if (b2 & ei.attackedBy[Them][BISHOP] & safe)
+ attackUnits += BishopCheck, score -= SafeCheck;
- // Enemy bishops safe checks
- b = b2 & ei.attackedBy[Them][BISHOP];
- if (b)
- attackUnits += BishopCheck * popcount<Max15>(b);
+ else if (b2 & ei.attackedBy[Them][BISHOP] & other)
+ score -= OtherCheck;
- // Enemy knights safe checks
- b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
- if (b)
- attackUnits += KnightCheck * popcount<Max15>(b);
+ // Enemy knights safe and other checks
+ b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
+ if (b & safe)
+ attackUnits += KnightCheck, score -= SafeCheck;
+
+ else if (b & other)
+ score -= OtherCheck;
// Finally, extract the king danger score from the KingDanger[]
- // array and subtract the score from evaluation.
+ // array and subtract the score from the evaluation.
score -= KingDanger[std::max(std::min(attackUnits, 399), 0)];
}
- if (Trace)
- Tracing::write(KING, Us, score);
+ // King tropism: firstly, find squares that opponent attacks in our king flank
+ b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[Us][file_of(ksq)];
+
+ assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
+ assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
+
+ // Secondly, add the squares which are attacked twice in that flank and
+ // which are not defended by our pawns.
+ b = (Us == WHITE ? b << 4 : b >> 4)
+ | (b & ei.attackedBy2[Them] & ~ei.attackedBy[Us][PAWN]);
+
+ score -= CloseEnemies * popcount(b);
+
+ if (DoTrace)
+ Trace::add(KING, Us, score);
return score;
}
- // evaluate_threats() assigns bonuses according to the type of attacking piece
- // and the type of attacked one.
+ // evaluate_threats() assigns bonuses according to the types of the attacking
+ // and the attacked pieces.
- template<Color Us, bool Trace>
+ template<Color Us, bool DoTrace>
Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- enum { Defended, Weak };
- enum { Minor, Major };
+ enum { Minor, Rook };
- Bitboard b, weak, defended;
+ Bitboard b, weak, defended, safeThreats;
Score score = SCORE_ZERO;
- // Non-pawn enemies defended by a pawn
- defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN))
- & ei.attackedBy[Them][PAWN];
+ // 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;
- // Add a bonus according to the kind of attacking pieces
- if (defended)
+ // Non-pawn enemies attacked by a pawn
+ weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];
+
+ if (weak)
{
- b = defended & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
- while (b)
- score += Threat[Defended][Minor][type_of(pos.piece_on(pop_lsb(&b)))];
+ b = pos.pieces(Us, PAWN) & ( ~ei.attackedBy[Them][ALL_PIECES]
+ | ei.attackedBy[Us][ALL_PIECES]);
- b = defended & (ei.attackedBy[Us][ROOK]);
- while (b)
- score += Threat[Defended][Major][type_of(pos.piece_on(pop_lsb(&b)))];
+ safeThreats = (shift_bb<Right>(b) | shift_bb<Left>(b)) & weak;
+
+ if (weak ^ safeThreats)
+ score += ThreatByHangingPawn;
+
+ 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];
+
// Enemies not defended by a pawn and under our attack
weak = pos.pieces(Them)
& ~ei.attackedBy[Them][PAWN]
& ei.attackedBy[Us][ALL_PIECES];
// Add a bonus according to the kind of attacking pieces
- if (weak)
+ if (defended | weak)
{
- b = weak & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+ b = (defended | weak) & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
while (b)
- score += Threat[Weak][Minor][type_of(pos.piece_on(pop_lsb(&b)))];
+ score += Threat[Minor][type_of(pos.piece_on(pop_lsb(&b)))];
- b = weak & (ei.attackedBy[Us][ROOK] | ei.attackedBy[Us][QUEEN]);
+ b = (pos.pieces(Them, QUEEN) | weak) & ei.attackedBy[Us][ROOK];
while (b)
- score += Threat[Weak][Major][type_of(pos.piece_on(pop_lsb(&b)))];
+ score += Threat[Rook ][type_of(pos.piece_on(pop_lsb(&b)))];
- b = weak & ~ei.attackedBy[Them][ALL_PIECES];
- if (b)
- score += Hanging * popcount<Max15>(b);
+ score += Hanging * popcount(weak & ~ei.attackedBy[Them][ALL_PIECES]);
b = weak & ei.attackedBy[Us][KING];
if (b)
- score += more_than_one(b) ? KingOnMany : KingOnOne;
+ score += ThreatByKing[more_than_one(b)];
}
- // Add bonus for safe pawn pushes which attacks an enemy piece
+ // 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()));
b &= ~pos.pieces()
& ~ei.attackedBy[Them][PAWN]
- & (ei.attackedBy[Us][PAWN] | ~ei.attackedBy[Them][ALL_PIECES]);
+ & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
b = (shift_bb<Left>(b) | shift_bb<Right>(b))
& pos.pieces(Them)
& ~ei.attackedBy[Us][PAWN];
- if(b)
- score += popcount<Max15>(b) * PawnAttackThreat;
+ score += ThreatByPawnPush * popcount(b);
- if (Trace)
- Tracing::write(Tracing::THREAT, Us, score);
+ if (DoTrace)
+ Trace::add(THREAT, Us, score);
return score;
}
// evaluate_passed_pawns() evaluates the passed pawns of the given color
- template<Color Us, bool Trace>
+ template<Color Us, bool DoTrace>
Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
Square s = pop_lsb(&b);
assert(pos.pawn_passed(Us, s));
+ assert(!(pos.pieces(PAWN) & forward_bb(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));
+ Value mbonus = Passed[MG][r], ebonus = Passed[EG][r];
if (rr)
{
Square blockSq = s + pawn_push(Us);
// Adjust bonus based on the king's proximity
- ebonus += distance(pos.king_square(Them), blockSq) * 5 * rr
- - distance(pos.king_square(Us ), blockSq) * 2 * rr;
+ ebonus += distance(pos.square<KING>(Them), blockSq) * 5 * rr
+ - distance(pos.square<KING>(Us ), blockSq) * 2 * rr;
// If blockSq is not the queening square then consider also a second push
if (relative_rank(Us, blockSq) != RANK_8)
- ebonus -= distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr;
+ ebonus -= distance(pos.square<KING>(Us), blockSq + pawn_push(Us)) * rr;
// If the pawn is free to advance, then increase the bonus
if (pos.empty(blockSq))
// 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;
+ int k = !unsafeSquares ? 18 : !(unsafeSquares & blockSq) ? 8 : 0;
- // If the path to queen is fully defended, assign a big bonus.
+ // 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;
mbonus += k * rr, ebonus += k * rr;
}
else if (pos.pieces(Us) & blockSq)
- mbonus += rr * 3 + r * 2 + 3, ebonus += rr + r * 2;
+ mbonus += rr + r * 2, ebonus += rr + r * 2;
} // rr != 0
- if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
- ebonus += ebonus / 4;
-
- score += make_score(mbonus, ebonus);
+ score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
}
- if (Trace)
- Tracing::write(Tracing::PASSED, Us, apply_weight(score, Weights[PassedPawns]));
+ if (DoTrace)
+ Trace::add(PASSED, Us, score);
// Add the scores to the middlegame and endgame eval
- return apply_weight(score, Weights[PassedPawns]);
+ return score;
}
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
+ // 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]
+ Bitboard safe = SpaceMask
& ~pos.pieces(Us, PAWN)
& ~ei.attackedBy[Them][PAWN]
& (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
behind |= (Us == WHITE ? behind >> 8 : behind << 8);
behind |= (Us == WHITE ? behind >> 16 : behind << 16);
- // Since SpaceMask[Us] is fully on our half of the board
+ // Since SpaceMask[Us] is fully on our half of the board...
assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
- // Count safe + (behind & safe) with a single popcount
- int bonus = popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
- int weight = pos.count<KNIGHT>(Us) + pos.count<BISHOP>(Us)
- + pos.count<KNIGHT>(Them) + pos.count<BISHOP>(Them);
+ // ...count safe + (behind & safe) with a single popcount
+ int bonus = popcount((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
+ bonus = std::min(16, bonus);
+ int weight = pos.count<ALL_PIECES>(Us);
- return make_score(bonus * weight * weight, 0);
+ return make_score(bonus * weight * weight / 22, 0);
}
- // 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 };
-
- // Initialize score by reading the incrementally updated scores included
- // in the position object (material + piece square tables).
- // Score is computed from the point of view of white.
- score = pos.psq_score();
-
- // Probe the material hash table
- ei.mi = Material::probe(pos);
- score += ei.mi->imbalance();
-
- // 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);
- score += apply_weight(ei.pi->pawns_score(), Weights[PawnStructure]);
-
- // Initialize attack and king safety bitboards
- init_eval_info<WHITE>(pos, ei);
- init_eval_info<BLACK>(pos, ei);
+ // 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) {
- ei.attackedBy[WHITE][ALL_PIECES] |= ei.attackedBy[WHITE][KING];
- ei.attackedBy[BLACK][ALL_PIECES] |= ei.attackedBy[BLACK][KING];
+ 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);
- // 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)) };
+ // Compute the initiative bonus for the attacking side
+ int initiative = 8 * (asymmetry + kingDistance - 15) + 12 * pawns;
- // Evaluate pieces and mobility
- score += evaluate_pieces<KNIGHT, WHITE, Trace>(pos, ei, mobility, mobilityArea);
- score += apply_weight(mobility[WHITE] - mobility[BLACK], Weights[Mobility]);
+ // 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));
- // 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);
+ return make_score(0, value);
+ }
- // 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);
+ // evaluate_scale_factor() computes the scale factor for the winning side
+ ScaleFactor evaluate_scale_factor(const Position& pos, const EvalInfo& ei, Value eg) {
- // If both sides have only pawns, score for potential unstoppable pawns
- if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
- {
- Bitboard b;
- if ((b = ei.pi->passed_pawns(WHITE)) != 0)
- score += int(relative_rank(WHITE, frontmost_sq(WHITE, b))) * Unstoppable;
-
- if ((b = ei.pi->passed_pawns(BLACK)) != 0)
- score -= int(relative_rank(BLACK, frontmost_sq(BLACK, b))) * Unstoppable;
- }
-
- // Evaluate space for both sides, only during opening
- if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)
- {
- Score s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
- score += apply_weight(s, Weights[Space]);
- }
-
- // Scale winning side if position is more drawish than it appears
- Color strongSide = eg_value(score) > VALUE_DRAW ? WHITE : BLACK;
- ScaleFactor sf = ei.mi->scale_factor(pos, strongSide);
+ Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
+ ScaleFactor sf = ei.me->scale_factor(pos, strongSide);
// If we don't already have an unusual scale factor, check for certain
// types of endgames, and use a lower scale for those.
- if ( ei.mi->game_phase() < PHASE_MIDGAME
+ 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 is even more a draw.
+ // 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(32) : ScaleFactor(8);
+ 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(50 * sf / SCALE_FACTOR_NORMAL);
+ sf = ScaleFactor(46);
}
// Endings where weaker side can place his king in front of the opponent's
// pawns are drawish.
- else if ( abs(eg_value(score)) <= BishopValueEg
- && ei.pi->pawn_span(strongSide) <= 1
- && !pos.pawn_passed(~strongSide, pos.king_square(~strongSide)))
- sf = ei.pi->pawn_span(strongSide) ? ScaleFactor(56) : ScaleFactor(38);
+ else if ( abs(eg) <= BishopValueEg
+ && pos.count<PAWN>(strongSide) <= 2
+ && !pos.pawn_passed(~strongSide, pos.square<KING>(~strongSide)))
+ sf = ScaleFactor(37 + 7 * pos.count<PAWN>(strongSide));
}
- // 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;
+ return sf;
+ }
+
+} // namespace
- v /= int(PHASE_MIDGAME);
- // In case of tracing add all single evaluation contributions for both white and black
- if (Trace)
- {
- Tracing::write(Tracing::MATERIAL, pos.psq_score());
- Tracing::write(Tracing::IMBALANCE, ei.mi->imbalance());
- Tracing::write(PAWN, ei.pi->pawns_score());
- Tracing::write(Tracing::MOBILITY, apply_weight(mobility[WHITE], Weights[Mobility])
- , apply_weight(mobility[BLACK], Weights[Mobility]));
- Tracing::write(Tracing::SPACE, apply_weight(evaluate_space<WHITE>(pos, ei), Weights[Space])
- , apply_weight(evaluate_space<BLACK>(pos, ei), Weights[Space]));
- Tracing::write(Tracing::TOTAL, score);
- Tracing::ei = ei;
- Tracing::sf = sf;
- }
+/// evaluate() is the main evaluation function. It returns a static evaluation
+/// of the position from the point of view of the side to move.
- return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo;
- }
+template<bool DoTrace>
+Value Eval::evaluate(const Position& pos) {
+ assert(!pos.checkers());
- // Tracing function definitions
+ EvalInfo ei;
+ Score score, mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
- double Tracing::to_cp(Value v) { return double(v) / PawnValueEg; }
+ // 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();
- void Tracing::write(int idx, Color c, Score s) { scores[c][idx] = s; }
+ // Probe the material hash table
+ ei.me = Material::probe(pos);
+ score += ei.me->imbalance();
- void Tracing::write(int idx, Score w, Score b) {
+ // 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);
- write(idx, WHITE, w);
- write(idx, BLACK, b);
- }
+ // Probe the pawn hash table
+ ei.pi = Pawns::probe(pos);
+ score += ei.pi->pawns_score();
- void Tracing::print(std::stringstream& ss, const char* name, int idx) {
-
- Score wScore = scores[WHITE][idx];
- Score bScore = scores[BLACK][idx];
-
- switch (idx) {
- case MATERIAL: case IMBALANCE: case PAWN: case TOTAL:
- ss << std::setw(15) << 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(15) << 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";
- }
- }
+ // Initialize attack and king safety bitboards
+ ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
+ ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.square<KING>(WHITE));
+ ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.square<KING>(BLACK));
+ eval_init<WHITE>(pos, ei);
+ eval_init<BLACK>(pos, ei);
- std::string Tracing::do_trace(const Position& pos) {
+ // 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)
+ };
- std::memset(scores, 0, sizeof(scores));
+ // 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))
+ };
- Value v = do_evaluate<true>(pos);
- v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
+ // Evaluate all pieces but king and pawns
+ score += evaluate_pieces<DoTrace>(pos, ei, mobility, mobilityArea);
+ score += mobility[WHITE] - mobility[BLACK];
- 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";
+ // 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);
- print(ss, "Material", MATERIAL);
- print(ss, "Imbalance", IMBALANCE);
- print(ss, "Pawns", PAWN);
- print(ss, "Knights", KNIGHT);
- print(ss, "Bishops", BISHOP);
- print(ss, "Rooks", ROOK);
- print(ss, "Queens", QUEEN);
- print(ss, "Mobility", MOBILITY);
- print(ss, "King safety", KING);
- print(ss, "Threats", THREAT);
- print(ss, "Passed pawns", PASSED);
- print(ss, "Space", SPACE);
+ // Evaluate tactical threats, we need full attack information including king
+ score += evaluate_threats<WHITE, DoTrace>(pos, ei)
+ - evaluate_threats<BLACK, DoTrace>(pos, ei);
- ss << "----------------+-------------+-------------+-------------\n";
- print(ss, "Total", TOTAL);
+ // 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);
- ss << "\nTotal Evaluation: " << to_cp(v) << " (white side)\n";
+ // 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)));
- return ss.str();
+ if ((b = ei.pi->passed_pawns(BLACK)) != 0)
+ score -= Unstoppable * int(relative_rank(BLACK, frontmost_sq(BLACK, b)));
}
-} // namespace
+ // 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);
+ // Evaluate position potential for the winning side
+ score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
-namespace Eval {
+ // Evaluate scale factor for the winning side
+ ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
- /// 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.
+ // 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;
- Value evaluate(const Position& pos) {
- return do_evaluate<false>(pos);
+ 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);
}
+ return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
+}
- /// 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);
- }
+// Explicit template instantiations
+template Value Eval::evaluate<true >(const Position&);
+template Value Eval::evaluate<false>(const Position&);
- /// init() computes evaluation weights, usually at startup
+/// 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.
- void init() {
+std::string Eval::trace(const Position& pos) {
- const double MaxSlope = 8.7;
- const double Peak = 1280;
- double t = 0.0;
+ std::memset(scores, 0, sizeof(scores));
- for (int i = 1; i < 400; ++i)
- {
- t = std::min(Peak, std::min(0.027 * i * i, t + MaxSlope));
- KingDanger[i] = apply_weight(make_score(int(t), 0), Weights[KingSafety]);
- }
- }
+ Value v = evaluate<true>(pos);
+ v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
-} // namespace Eval
+ 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();
+}
+
+
+/// init() computes evaluation weights, usually at startup
+
+void Eval::init() {
+
+ const int MaxSlope = 322;
+ const int Peak = 47410;
+ int t = 0;
+
+ 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