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 Trace {
- enum Term { // First 8 entries are for PieceType
+ enum Term { // The first 8 entries are for PieceType
MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
};
// 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.
Pawns::Entry* pi;
};
-
- // Evaluation weights, indexed by the corresponding evaluation term
- enum { PawnStructure, PassedPawns, Space, KingSafety };
-
- const struct Weight { int mg, eg; } Weights[] = {
- {214, 203}, {193, 262}, {47, 0}, {330, 0}
- };
-
- Score operator*(Score s, const Weight& w) {
- return make_score(mg_value(s) * w.mg / 256, eg_value(s) * w.eg / 256);
- }
-
-
#define V(v) Value(v)
#define S(mg, eg) make_score(mg, eg)
// Outpost[knight/bishop][supported by pawn] contains bonuses for knights and
// bishops outposts, bigger if outpost piece is supported by a pawn.
const Score Outpost[][2] = {
- { S(42,11), S(63,17) }, // Knights
- { S(18, 5), S(27, 8) } // Bishops
+ { 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(31, 8) }, // Knights
- { S( 8, 2), S(13, 4) } // Bishops
+ { S(21, 5), S(35, 8) }, // Knights
+ { S( 8, 0), S(14, 4) } // Bishops
};
- // Threat[minor/rook][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.
- // Attacks on lesser pieces which are pawn defended are not considered.
- const Score Threat[2][PIECE_TYPE_NB] = {
- { S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72, 107), S(48,118) }, // Minor attacks
- { S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48) } // Rook attacks
+ // 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 a pawn.
- const Score ThreatenedByPawn[PIECE_TYPE_NB] = {
- S(0, 0), S(0, 0), S(176, 139), S(131, 127), S(217, 218), S(203, 215)
- };
+ // 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(0), V( 1), V(34), V(90), V(214), V(328) },
- { V(7), V(14), V(37), V(63), V(134), V(189) }
+ { 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[] = {
- S( 12, 10), S( 3, 10), S( 1, -8), S(-27, -12),
- S(-27, -12), S( 1, -8), S( 3, 10), S( 12, 10)
+ // 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)
};
- const Score ThreatenedByHangingPawn = S(70, 63);
-
// Assorted bonuses and penalties used by evaluation
- const Score KingOnOne = S( 3, 62);
- const Score KingOnMany = S( 9,138);
- 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(48, 28);
- const Score PawnAttackThreat = S(31, 19);
- const Score Checked = 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 Checked = S(20, 20);
+ const Score ThreatByHangingPawn = S(71, 61);
+ const Score LooseEnemies = S( 0, 25);
+ 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
// Penalties for enemy's safe checks
const int QueenContactCheck = 89;
- const int QueenCheck = 50;
+ const int QueenCheck = 52;
const int RookCheck = 45;
- const int BishopCheck = 6;
- const int KnightCheck = 14;
+ const int BishopCheck = 5;
+ const int KnightCheck = 17;
- // eval_init() initializes king and attack bitboards for given color
+ // 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>
{
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
{
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 & mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt][mob];
&& (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.square<KING>(Us);
if (DoTrace)
Trace::add(Pt, Us, score);
- // Recursively call evaluate_pieces() of next piece type until KING excluded
+ // Recursively call evaluate_pieces() of next piece type until KING is excluded
return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility, mobilityArea);
}
// Main king safety evaluation
if (ei.kingAttackersCount[Them])
{
- // Find the attacked squares around the king which have no defenders
- // apart from the king itself.
+ // 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
// 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]
+ + 27 * popcount(undefended)
+ + 11 * (popcount(b) + !!ei.pinnedPieces[Us])
- 64 * !pos.count<QUEEN>(Them)
- mg_value(score) / 8;
| ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]
| ei.attackedBy[Them][KING];
- if (b)
- attackUnits += QueenContactCheck * popcount<Max15>(b);
+ attackUnits += QueenContactCheck * popcount(b);
}
// Analyse the enemy's safe distance checks for sliders and knights
b2 = pos.attacks_from<BISHOP>(ksq) & safe;
// Enemy queen safe checks
- b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
- if (b)
- {
- attackUnits += QueenCheck * popcount<Max15>(b);
- score -= Checked;
- }
+ if ((b1 | b2) & ei.attackedBy[Them][QUEEN])
+ attackUnits += QueenCheck, score -= Checked;
// Enemy rooks safe checks
- b = b1 & ei.attackedBy[Them][ROOK];
- if (b)
- {
- attackUnits += RookCheck * popcount<Max15>(b);
- score -= Checked;
- }
+ if (b1 & ei.attackedBy[Them][ROOK])
+ attackUnits += RookCheck, score -= Checked;
// Enemy bishops safe checks
- b = b2 & ei.attackedBy[Them][BISHOP];
- if (b)
- {
- attackUnits += BishopCheck * popcount<Max15>(b);
- score -= Checked;
- }
+ if (b2 & ei.attackedBy[Them][BISHOP])
+ attackUnits += BishopCheck, score -= Checked;
// Enemy knights safe checks
- b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
- if (b)
- {
- attackUnits += KnightCheck * popcount<Max15>(b);
- score -= Checked;
- }
+ if (pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe)
+ attackUnits += KnightCheck, score -= Checked;
// 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)];
}
}
- // 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 DoTrace>
Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
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];
safeThreats = (shift_bb<Right>(b) | shift_bb<Left>(b)) & weak;
if (weak ^ safeThreats)
- score += ThreatenedByHangingPawn;
+ score += ThreatByHangingPawn;
while (safeThreats)
- score += ThreatenedByPawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
+ score += ThreatBySafePawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
}
// Non-pawn enemies defended by a pawn
while (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)];
}
// Bonus if some pawns can safely push and attack an enemy piece
& pos.pieces(Them)
& ~ei.attackedBy[Us][PAWN];
- if (b)
- score += popcount<Max15>(b) * PawnAttackThreat;
+ score += ThreatByPawnPush * popcount(b);
if (DoTrace)
Trace::add(THREAT, Us, score);
// assign a smaller bonus if the block square isn't attacked.
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) + PassedFile[file_of(s)];
}
if (DoTrace)
- Trace::add(PASSED, Us, score * Weights[PassedPawns]);
+ Trace::add(PASSED, Us, score);
// Add the scores to the middlegame and endgame eval
- return score * Weights[PassedPawns];
+ return score;
}
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 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);
- return make_score(bonus * weight * weight, 0);
+ return make_score(bonus * weight * weight * 2 / 11, 0);
}
// evaluate_initiative() computes the initiative correction value for the
- // position, i.e. second order bonus/malus based on the known attacking/defending
+ // 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) {
- int kingDistance = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
+ 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);
// Compute the initiative bonus for the attacking side
- int initiative = 8 * (pawns + asymmetry + kingDistance - 15);
+ int initiative = 8 * (asymmetry + kingDistance - 15) + 12 * pawns;
// 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
// evaluate_scale_factor() computes the scale factor for the winning side
- ScaleFactor evaluate_scale_factor(const Position& pos, const EvalInfo& ei, Score score) {
+ ScaleFactor evaluate_scale_factor(const Position& pos, const EvalInfo& ei, Value eg) {
- Color strongSide = eg_value(score) > VALUE_DRAW ? WHITE : BLACK;
+ 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
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(31) : ScaleFactor(9);
}
// Endings where weaker side can place his king in front of the opponent's
// pawns are drawish.
- else if ( abs(eg_value(score)) <= BishopValueEg
+ 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);
// Probe the pawn hash table
ei.pi = Pawns::probe(pos);
- score += ei.pi->pawns_score() * Weights[PawnStructure];
+ score += ei.pi->pawns_score();
// Initialize attack and king safety bitboards
ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
{
Bitboard b;
if ((b = ei.pi->passed_pawns(WHITE)) != 0)
- score += int(relative_rank(WHITE, frontmost_sq(WHITE, b))) * Unstoppable;
+ score += Unstoppable * int(relative_rank(WHITE, frontmost_sq(WHITE, b)));
if ((b = ei.pi->passed_pawns(BLACK)) != 0)
- score -= int(relative_rank(BLACK, frontmost_sq(BLACK, b))) * Unstoppable;
+ 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)) * Weights[Space];
+ 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));
// Evaluate scale factor for the winning side
- ScaleFactor sf = evaluate_scale_factor(pos, ei, score);
+ 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())
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) * Weights[Space]
- , evaluate_space<BLACK>(pos, ei) * Weights[Space]);
+ Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)
+ , evaluate_space<BLACK>(pos, ei));
Trace::add(TOTAL, score);
}
void Eval::init() {
- const int MaxSlope = 8700;
- const int Peak = 1280000;
+ 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 * 27, t + MaxSlope));
- KingDanger[i] = make_score(t / 1000, 0) * Weights[KingSafety];
+ t = std::min(Peak, std::min(i * i - 16, t + MaxSlope));
+ KingDanger[i] = make_score(t * 268 / 7700, 0);
}
}
projects / stockfish / blobdiff