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
+ Copyright (C) 2015-2017 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"
// by the evaluation functions.
struct EvalInfo {
+ Material::Entry* me;
+ Pawns::Entry* pe;
+ Bitboard mobilityArea[COLOR_NB];
+
// 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];
+ // 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)
// 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;
};
#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.
+ // MobilityBonus[PieceType][attacked] contains bonuses for middle and end game,
+ // indexed by piece type and number of attacked squares in the mobility area.
const Score MobilityBonus[][32] = {
{}, {},
- { S(-75,-76), S(-56,-54), S(- 9,-26), S( -2,-10), S( 6, 5), S( 15, 11), // Knights
+ { 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(118,174), S(119,177), S(123,191), S(128,199) }
};
- // Outpost[knight/bishop][supported by pawn] contains bonuses for knights and
- // bishops outposts, bigger if outpost piece is supported by a pawn.
+ // Outpost[knight/bishop][supported by pawn] contains bonuses for minor
+ // pieces if they can reach an outpost square, bigger if that square is
+ // supported by a pawn. If the minor piece occupies an outpost square
+ // then score is doubled.
const Score Outpost[][2] = {
- { S(42,11), S(63,17) }, // Knights
- { S(18, 5), S(27, 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(31, 8) }, // Knights
- { S( 8, 2), S(13, 4) } // Bishops
+ { S(22, 6), S(33, 9) }, // Knight
+ { S( 9, 2), S(14, 4) } // Bishop
};
// RookOnFile[semiopen/open] contains bonuses for each rook when there is no
// friendly pawn on the rook file.
- const Score RookOnFile[2] = { S(19, 10), S(43, 21) };
+ 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
+ S(0, 0), S(0, 0), S(176, 139), S(131, 127), S(217, 218), S(203, 215)
+ };
+
+ // ThreatByMinor/ByRook[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 ThreatByMinor[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72, 107), S(48, 118)
};
- // ThreatByKing[on one/on many] contains bonuses for King attacks on
+ const Score ThreatByRook[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48)
+ };
+
+ // 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) };
// 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)
+ 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( 7, 27);
+ const Score RookOnPawn = S( 8, 24);
const Score TrappedRook = S(92, 0);
- const Score Checked = S(20, 20);
- const Score ThreatByHangingPawn = S(70, 63);
- const Score Hanging = S(48, 28);
- const Score ThreatByPawnPush = S(31, 19);
- const Score Unstoppable = S( 0, 20);
+ const Score WeakQueen = S(50, 10);
+ const Score OtherCheck = S(10, 10);
+ const Score CloseEnemies = S( 7, 0);
+ const Score PawnlessFlank = S(20, 80);
+ const Score LooseEnemies = S( 0, 25);
+ const Score ThreatByHangingPawn = S(71, 61);
+ const Score ThreatByRank = S(16, 3);
+ const Score Hanging = S(48, 27);
+ const Score ThreatByPawnPush = S(38, 22);
+ const Score HinderPassedPawn = S( 7, 0);
// 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
- // 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[PIECE_TYPE_NB] = { 0, 0, 7, 5, 4, 1 };
+ const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 78, 56, 45, 11 };
// Penalties for enemy's safe checks
- const int QueenContactCheck = 89;
- const int QueenCheck = 50;
- const int RookCheck = 45;
- const int BishopCheck = 6;
- const int KnightCheck = 14;
+ const int QueenContactCheck = 997;
+ const int QueenCheck = 745;
+ const int RookCheck = 688;
+ const int BishopCheck = 588;
+ const int KnightCheck = 924;
+ // Threshold for lazy evaluation
+ const Value LazyThreshold = Value(1500);
// 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 eval_init(const Position& pos, EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? NORTH : SOUTH);
+ const Square Down = (Us == WHITE ? SOUTH : NORTH);
+ const Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB: Rank7BB | Rank6BB);
+
+ // Find our pawns on the first two ranks, and those which are blocked
+ Bitboard b = pos.pieces(Us, PAWN) & (shift<Down>(pos.pieces()) | LowRanks);
+
+ // Squares occupied by those pawns, by our king, or controlled by enemy pawns
+ // are excluded from the mobility area.
+ ei.mobilityArea[Us] = ~(b | pos.square<KING>(Us) | ei.pe->pawn_attacks(Them));
- 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);
+ // Initialise the attack bitboards with the king and pawn information
+ b = ei.attackedBy[Us][KING] = pos.attacks_from<KING>(pos.square<KING>(Us));
+ ei.attackedBy[Us][PAWN] = ei.pe->pawn_attacks(Us);
- // Init king safety tables only if we are going to use them
- if (pos.non_pawn_material(Us) >= QueenValueMg)
+ ei.attackedBy2[Us] = b & ei.attackedBy[Us][PAWN];
+ ei.attackedBy[Us][ALL_PIECES] = b | ei.attackedBy[Us][PAWN];
+
+ // Init our king safety tables only if we are going to use them
+ if (pos.non_pawn_material(Them) >= QueenValueMg)
{
- ei.kingRing[Them] = b | shift_bb<Down>(b);
- b &= ei.attackedBy[Us][PAWN];
- ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) : 0;
- ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
+ ei.kingRing[Us] = b | shift<Up>(b);
+ ei.kingAttackersCount[Them] = popcount(b & ei.pe->pawn_attacks(Them));
+ ei.kingAdjacentZoneAttacksCount[Them] = ei.kingAttackersWeight[Them] = 0;
}
else
- ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
+ ei.kingRing[Us] = ei.kingAttackersCount[Them] = 0;
}
// color and type.
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;
+ Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility) {
const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
const Color Them = (Us == WHITE ? BLACK : WHITE);
: Rank5BB | Rank4BB | Rank3BB);
const Square* pl = pos.squares<Pt>(Us);
+ Bitboard b, bb;
+ Square s;
+ Score score = SCORE_ZERO;
+
ei.attackedBy[Us][Pt] = 0;
while ((s = *pl++) != SQ_NONE)
: Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
: pos.attacks_from<Pt>(s);
- if (ei.pinnedPieces[Us] & s)
+ if (pos.pinned_pieces(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];
- 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 = popcount<Pt == QUEEN ? Full : Max15>(b & mobilityArea[Us]);
+ int mob = popcount(b & ei.mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt][mob];
if (Pt == BISHOP || Pt == KNIGHT)
{
// Bonus for outpost squares
- bb = OutpostRanks & ~ei.pi->pawn_attacks_span(Them);
+ bb = OutpostRanks & ~ei.pe->pawn_attacks_span(Them);
if (bb & s)
- score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & s)];
+ score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & s)] * 2;
else
{
bb &= b & ~pos.pieces(Us);
if (bb)
- score += ReachableOutpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & bb)];
+ score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & bb)];
}
// Bonus when behind a pawn
// 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);
+ score -= BishopPawns * ei.pe->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
&& 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);
+ Square d = pawn_push(Us) + (file_of(s) == FILE_A ? EAST : WEST);
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
{
// 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 += RookOnPawn * popcount<Max15>(alignedPawns);
- }
+ 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 += RookOnFile[!!ei.pi->semiopen_file(Them, file_of(s))];
+ if (ei.pe->semiopen_file(Us, file_of(s)))
+ score += RookOnFile[!!ei.pe->semiopen_file(Them, file_of(s))];
- // Penalize when trapped by the king, even more if the king cannot castle
+ // Penalty when trapped by the king, even more if the king cannot castle
else if (mob <= 3)
{
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)
- && !ei.pi->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
+ && !ei.pe->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
}
}
+
+ if (Pt == QUEEN)
+ {
+ // Penalty if any relative pin or discovered attack against the queen
+ Bitboard pinners;
+ if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s, pinners))
+ score -= WeakQueen;
+ }
}
if (DoTrace)
Trace::add(Pt, Us, score);
// Recursively call evaluate_pieces() of next piece type until KING is excluded
- return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility, mobilityArea);
+ return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility);
}
template<>
- Score evaluate_pieces<false, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
+ Score evaluate_pieces<false, WHITE, KING>(const Position&, EvalInfo&, Score*) { return SCORE_ZERO; }
template<>
- Score evaluate_pieces< true, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
+ Score evaluate_pieces< true, WHITE, KING>(const Position&, EvalInfo&, Score*) { return SCORE_ZERO; }
// evaluate_king() assigns bonuses and penalties to a king of a given color
+ const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+
+ const Bitboard KingFlank[FILE_NB] = {
+ CenterFiles >> 2, CenterFiles >> 2, CenterFiles >> 2, CenterFiles, CenterFiles,
+ CenterFiles << 2, CenterFiles << 2, CenterFiles << 2
+ };
+
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 ? NORTH : SOUTH);
+ const Bitboard Camp = (Us == WHITE ? ~Bitboard(0) ^ Rank6BB ^ Rank7BB ^ Rank8BB
+ : ~Bitboard(0) ^ Rank1BB ^ Rank2BB ^ Rank3BB);
- Bitboard undefended, b, b1, b2, safe;
- int attackUnits;
const Square ksq = pos.square<KING>(Us);
+ Bitboard undefended, b, b1, b2, safe, other;
+ int kingDanger;
// King shelter and enemy pawns storm
- Score score = ei.pi->king_safety<Us>(pos, ksq);
+ Score score = ei.pe->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]);
-
- // Initialize the 'attackUnits' variable, which is used later on as an
- // index into the KingDanger[] array. The initial value is based on the
+ // Find the attacked squares which are defended only by our 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 'kingDanger' variable, which will be transformed
+ // later into a king danger score. 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]
- + 27 * popcount<Max15>(undefended)
- + 11 * !!ei.pinnedPieces[Us]
- - 64 * !pos.count<QUEEN>(Them)
- - mg_value(score) / 8;
+ kingDanger = std::min(807, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
+ + 101 * ei.kingAdjacentZoneAttacksCount[Them]
+ + 235 * popcount(undefended)
+ + 134 * (popcount(b) + !!pos.pinned_pieces(Us))
+ - 717 * !pos.count<QUEEN>(Them)
+ - 7 * mg_value(score) / 5 - 5;
// Analyse the enemy's safe queen contact checks. Firstly, find the
- // undefended squares around the king reachable by the enemy queen...
+ // undefended squares around our 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];
- if (b)
- attackUnits += QueenContactCheck * popcount<Max15>(b);
- }
+ // ...and keep squares supported by another enemy piece.
+ kingDanger += QueenContactCheck * popcount(b & ei.attackedBy2[Them]);
- // Analyse the enemy's safe distance checks for sliders and knights
- safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
+ // Analyse the safe enemy's checks which are possible on next move
+ safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
- b1 = pos.attacks_from<ROOK >(ksq) & safe;
- b2 = pos.attacks_from<BISHOP>(ksq) & safe;
+ b1 = pos.attacks_from<ROOK >(ksq);
+ b2 = pos.attacks_from<BISHOP>(ksq);
// Enemy queen safe checks
- if ((b1 | b2) & ei.attackedBy[Them][QUEEN])
- attackUnits += QueenCheck, score -= Checked;
+ if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
+ kingDanger += QueenCheck;
+
+ // For minors and rooks, also consider the square safe if attacked twice,
+ // and only defended by our queen.
+ safe |= ei.attackedBy2[Them]
+ & ~(ei.attackedBy2[Us] | pos.pieces(Them))
+ & ei.attackedBy[Us][QUEEN];
+
+ // Some other potential checks are also analysed, even from squares
+ // currently occupied by the opponent own pieces, as long as the square
+ // is not attacked by our pawns, and is not occupied by a blocked pawn.
+ other = ~( ei.attackedBy[Us][PAWN]
+ | (pos.pieces(Them, PAWN) & shift<Up>(pos.pieces(PAWN))));
+
+ // Enemy rooks safe and other checks
+ if (b1 & ei.attackedBy[Them][ROOK] & safe)
+ kingDanger += RookCheck;
+
+ else if (b1 & ei.attackedBy[Them][ROOK] & other)
+ score -= OtherCheck;
+
+ // Enemy bishops safe and other checks
+ if (b2 & ei.attackedBy[Them][BISHOP] & safe)
+ kingDanger += BishopCheck;
+
+ else if (b2 & ei.attackedBy[Them][BISHOP] & other)
+ score -= OtherCheck;
+
+ // Enemy knights safe and other checks
+ b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
+ if (b & safe)
+ kingDanger += KnightCheck;
+
+ else if (b & other)
+ score -= OtherCheck;
+
+ // Transform the kingDanger units into a Score, and substract it from the evaluation
+ if (kingDanger > 0)
+ score -= make_score(std::min(kingDanger * kingDanger / 4096, 2 * int(BishopValueMg)), 0);
+ }
- // Enemy rooks safe checks
- if (b1 & ei.attackedBy[Them][ROOK])
- attackUnits += RookCheck, score -= Checked;
+ // King tropism: firstly, find squares that opponent attacks in our king flank
+ File kf = file_of(ksq);
+ b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[kf] & Camp;
- // Enemy bishops safe checks
- if (b2 & ei.attackedBy[Them][BISHOP])
- attackUnits += BishopCheck, score -= Checked;
+ assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
+ assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
- // Enemy knights safe checks
- if (pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe)
- attackUnits += KnightCheck, score -= Checked;
+ // 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]);
- // 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)];
- }
+ score -= CloseEnemies * popcount(b);
+
+ // Penalty when our king is on a pawnless flank
+ if (!(pos.pieces(PAWN) & KingFlank[kf]))
+ score -= PawnlessFlank;
if (DoTrace)
Trace::add(KING, Us, score);
template<Color Us, bool DoTrace>
Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
- 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 };
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? NORTH : SOUTH);
+ const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
+ const Square Right = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
+ const Bitboard TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
+ const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
Bitboard b, weak, defended, safeThreats;
Score score = SCORE_ZERO;
+ // 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;
+
// Non-pawn enemies attacked by a pawn
weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];
b = pos.pieces(Us, PAWN) & ( ~ei.attackedBy[Them][ALL_PIECES]
| ei.attackedBy[Us][ALL_PIECES]);
- safeThreats = (shift_bb<Right>(b) | shift_bb<Left>(b)) & weak;
+ safeThreats = (shift<Right>(b) | shift<Left>(b)) & weak;
if (weak ^ safeThreats)
score += ThreatByHangingPawn;
{
b = (defended | weak) & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
while (b)
- score += Threat[Minor][type_of(pos.piece_on(pop_lsb(&b)))];
+ {
+ Square s = pop_lsb(&b);
+ score += ThreatByMinor[type_of(pos.piece_on(s))];
+ if (type_of(pos.piece_on(s)) != PAWN)
+ score += ThreatByRank * (int)relative_rank(Them, s);
+ }
b = (pos.pieces(Them, QUEEN) | weak) & ei.attackedBy[Us][ROOK];
while (b)
- score += Threat[Rook ][type_of(pos.piece_on(pop_lsb(&b)))];
+ {
+ Square s = pop_lsb(&b);
+ score += ThreatByRook[type_of(pos.piece_on(s))];
+ if (type_of(pos.piece_on(s)) != PAWN)
+ score += ThreatByRank * (int)relative_rank(Them, s);
+ }
- 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)
// 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 = shift<Up>(b | (shift<Up>(b & TRank2BB) & ~pos.pieces()));
b &= ~pos.pieces()
& ~ei.attackedBy[Them][PAWN]
& (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
- b = (shift_bb<Left>(b) | shift_bb<Right>(b))
+ b = (shift<Left>(b) | shift<Right>(b))
& pos.pieces(Them)
& ~ei.attackedBy[Us][PAWN];
- if (b)
- score += ThreatByPawnPush * popcount<Max15>(b);
+ score += ThreatByPawnPush * popcount(b);
if (DoTrace)
Trace::add(THREAT, Us, score);
}
- // evaluate_passed_pawns() evaluates the passed pawns of the given color
+ // evaluate_passer_pawns() evaluates the passed pawns and candidate passed
+ // pawns of the given color.
template<Color Us, bool DoTrace>
- Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
+ Score evaluate_passer_pawns(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
- Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
+ Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
Score score = SCORE_ZERO;
- b = ei.pi->passed_pawns(Us);
+ b = ei.pe->passed_pawns(Us);
while (b)
{
Square s = pop_lsb(&b);
- assert(pos.pawn_passed(Us, s));
+ assert(!(pos.pieces(PAWN) & forward_bb(Us, s)));
+
+ bb = forward_bb(Us, s) & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
+ score -= HinderPassedPawn * popcount(bb);
int r = relative_rank(Us, s) - RANK_2;
int rr = r * (r - 1);
// in the pawn's path attacked or occupied by the enemy.
defendedSquares = unsafeSquares = squaresToQueen = forward_bb(Us, s);
- Bitboard bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
+ bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
if (!(pos.pieces(Us) & bb))
defendedSquares &= ei.attackedBy[Us][ALL_PIECES];
mbonus += rr + r * 2, ebonus += rr + r * 2;
} // rr != 0
- if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
- ebonus += ebonus / 4;
+ // Assign a small bonus when the opponent has no pieces left
+ if (!pos.non_pawn_material(Them))
+ ebonus += 20;
+
+ // Scale down bonus for candidate passers which need more than one pawn
+ // push to become passed.
+ if (!pos.pawn_passed(Us, s + pawn_push(Us)))
+ mbonus /= 2, ebonus /= 2;
score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
}
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);
+ Us == WHITE ? CenterFiles & (Rank2BB | Rank3BB | Rank4BB)
+ : CenterFiles & (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
// 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) - 2 * ei.pe->open_files();
- return make_score(bonus * weight * weight * 2 / 11, 0);
+ return make_score(bonus * weight * weight / 18, 0);
}
// 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);
+ sf = ScaleFactor(46);
}
// 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.count<PAWN>(strongSide) <= 2
&& !pos.pawn_passed(~strongSide, pos.square<KING>(~strongSide)))
- sf = ei.pi->pawn_span(strongSide) ? ScaleFactor(51) : ScaleFactor(37);
+ sf = ScaleFactor(37 + 7 * pos.count<PAWN>(strongSide));
}
return sf;
assert(!pos.checkers());
+ Score mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
+ Value v;
EvalInfo ei;
- Score score, mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
-
- // 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();
// 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);
+ // Initialize score by reading the incrementally updated scores included in
+ // the position object (material + piece square tables) and the material
+ // imbalance. Score is computed internally from the white point of view.
+ Score score = pos.psq_score() + ei.me->imbalance();
+
// Probe the pawn hash table
- ei.pi = Pawns::probe(pos);
- score += ei.pi->pawns_score();
+ ei.pe = Pawns::probe(pos);
+ score += ei.pe->pawns_score();
+
+ // Early exit if score is high
+ v = (mg_value(score) + eg_value(score)) / 2;
+ if (abs(v) > LazyThreshold)
+ return pos.side_to_move() == WHITE ? v : -v;
// 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)
- };
-
- // 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 += evaluate_pieces<DoTrace>(pos, ei, mobility);
score += mobility[WHITE] - mobility[BLACK];
// Evaluate kings after all other pieces because we need full attack
- evaluate_threats<BLACK, DoTrace>(pos, ei);
// 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);
-
- // 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)));
-
- if ((b = ei.pi->passed_pawns(BLACK)) != 0)
- score -= Unstoppable * int(relative_rank(BLACK, frontmost_sq(BLACK, b)));
- }
+ score += evaluate_passer_pawns<WHITE, DoTrace>(pos, ei)
+ - evaluate_passer_pawns<BLACK, DoTrace>(pos, ei);
// Evaluate space for both sides, only during opening
if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
- evaluate_space<BLACK>(pos, ei);
// Evaluate position potential for the winning side
- score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
+ score += evaluate_initiative(pos, ei.pe->pawn_asymmetry(), eg_value(score));
// Evaluate scale factor for the winning side
ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
// 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 = 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);
{
Trace::add(MATERIAL, pos.psq_score());
Trace::add(IMBALANCE, ei.me->imbalance());
- Trace::add(PAWN, ei.pi->pawns_score());
+ Trace::add(PAWN, ei.pe->pawns_score());
Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
- Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)
- , evaluate_space<BLACK>(pos, ei));
+ if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
+ Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)
+ , evaluate_space<BLACK>(pos, ei));
Trace::add(TOTAL, score);
}
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