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.
int kingAdjacentZoneAttacksCount[COLOR_NB];
Bitboard pinnedPieces[COLOR_NB];
+ Material::Entry* me;
Pawns::Entry* pi;
};
-
- // Evaluation weights, indexed by the corresponding 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}
- };
-
- 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)
// 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(-68,-49), S(-46,-33), S(-3,-12), S( 5, -4), S( 9, 11), S(15, 16), // Knights
- S( 23, 27), S( 33, 28), S(37, 29) },
- { S(-49,-44), S(-23,-16), S(16, 1), S(29, 16), S(40, 25), S(51, 34), // Bishops
- S( 55, 43), S( 61, 49), S(64, 51), S(68, 52), S(73, 55), S(75, 60),
- S( 80, 65), S( 86, 66) },
- { S(-50,-57), S(-28,-22), S(-11, 7), S(-1, 29), S( 0, 39), S( 1, 46), // Rooks
- S( 10, 66), S( 16, 79), S(22, 86), S(23,103), S(30,109), S(33,111),
- S( 37,115), S( 38,119), S(48,124) },
- { S(-43,-30), S(-27,-15), S( 1, -5), S( 2, -3), S(14, 10), S(18, 24), // Queens
- S( 20, 27), S( 33, 37), S(33, 38), S(34, 43), S(40, 46), S(43, 56),
- S( 46, 61), S( 52, 63), S(52, 63), S(57, 65), S(60, 70), S(61, 74),
- S( 67, 80), S( 76, 82), S(77, 88), S(82, 94), S(86, 95), S(90, 96),
- S( 94, 99), S( 96,100), S(99,111), S(99,112) }
+ { 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[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
};
- // Threat[defended/weak][minor/major attacking][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
+ // 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
};
- // ThreatenedByPawn[PieceType] contains a penalty according to which piece
- // type is attacked by an enemy pawn.
- const Score ThreatenedByPawn[PIECE_TYPE_NB] = {
- S(0, 0), S(0, 0), S(107, 138), S(84, 122), S(114, 203), S(121, 217)
+ // RookOnFile[semiopen/open] contains bonuses for each rook when there is no
+ // friendly pawn on the rook file.
+ const Score RookOnFile[2] = { S(20, 7), S(45, 20) };
+
+ // ThreatBySafePawn[PieceType] contains bonuses according to which piece
+ // type is attacked by a pawn which is protected or is not attacked.
+ const Score ThreatBySafePawn[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 0), S(176, 139), S(131, 127), S(217, 218), S(203, 215) };
+
+ // Threat[by minor/by rook][attacked PieceType] contains
+ // bonuses according to which piece type attacks which one.
+ // Attacks on lesser pieces which are pawn-defended are not considered.
+ const Score Threat[][PIECE_TYPE_NB] = {
+ { S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72,107), S(48,118) }, // by Minor
+ { S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48) } // by Rook
};
- // Passed[mg/eg][rank] contains midgame and endgame bonuses for passed pawns.
+ // 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) }
};
- const Score ThreatenedByHangingPawn = S(40, 60);
+ // 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 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
#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[COLOR_NB] = {
- (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
// 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;
+ const int QueenCheck = 52;
+ const int RookCheck = 45;
+ const int BishopCheck = 5;
+ const int KnightCheck = 17;
- // 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 Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
{
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_pieces() assigns bonuses and penalties to the pieces of a given color
+ // evaluate_pieces() assigns bonuses and penalties to the pieces of a given
+ // color and type.
- template<PieceType Pt, Color Us, bool DoTrace>
- Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility, const Bitboard* mobilityArea) {
-
- 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 Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
+ : Rank5BB | Rank4BB | Rank3BB);
const Square* pl = pos.squares<Pt>(Us);
ei.attackedBy[Us][Pt] = 0;
{
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 = popcount<Pt == QUEEN ? Full : Max15>(b & mobilityArea[Us]);
+ int mob = popcount(b & mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt][mob];
if (Pt == BISHOP || Pt == KNIGHT)
{
- // Bonus for outpost square
- if ( relative_rank(Us, s) >= RANK_4
- && relative_rank(Us, s) <= RANK_6
- && !(pos.pieces(Them, PAWN) & pawn_attack_span(Us, 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.square<KING>(Us);
if (DoTrace)
Trace::add(Pt, Us, score);
- // Recursively call evaluate_pieces() of next piece type until KING excluded
- return score - evaluate_pieces<NextPt, Them, DoTrace>(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*, const 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*, const 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
// 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
// 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]
- - 60 * !pos.count<QUEEN>(Them)
+ attackUnits = std::min(72, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
+ + 9 * ei.kingAdjacentZoneAttacksCount[Them]
+ + 27 * popcount(undefended)
+ + 11 * (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
{
// ...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);
- }
-
- // 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);
-
- // Consider only squares where the enemy's rook gives check
- b &= PseudoAttacks[ROOK][ksq];
-
- if (b)
- {
- // ...and then remove squares not supported by another enemy piece
- b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
- | ei.attackedBy[Them][BISHOP]);
+ | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]
+ | ei.attackedBy[Them][KING];
- if (b)
- attackUnits += RookContactCheck * 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) {
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, 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
defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Them][PAWN];
- // Add a bonus according to the kind of attacking pieces
- if (defended)
- {
- 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 = defended & (ei.attackedBy[Us][ROOK]);
- while (b)
- score += Threat[Defended][Major][type_of(pos.piece_on(pop_lsb(&b)))];
- }
-
// 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)];
}
// 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);
// 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 (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;
}
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]);
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
+ // 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))
+ - 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 * (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
+ // that the endgame score will never be divided by more than two.
+ int value = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg / 2));
+
+ return make_score(0, value);
+ }
+
+
+ // evaluate_scale_factor() computes the scale factor for the winning side
+ ScaleFactor evaluate_scale_factor(const Position& pos, const EvalInfo& ei, Value eg) {
+
+ Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
+ ScaleFactor sf = ei.me->scale_factor(pos, strongSide);
+
+ // If we don't already have an unusual scale factor, check for certain
+ // types of endgames, and use a lower scale for those.
+ if ( ei.me->game_phase() < PHASE_MIDGAME
+ && (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN))
+ {
+ if (pos.opposite_bishops())
+ {
+ // Endgame with opposite-colored bishops and no other pieces (ignoring pawns)
+ // is almost a draw, in case of KBP vs KB, it is even more a draw.
+ if ( pos.non_pawn_material(WHITE) == BishopValueMg
+ && pos.non_pawn_material(BLACK) == BishopValueMg)
+ sf = more_than_one(pos.pieces(PAWN)) ? ScaleFactor(31) : ScaleFactor(9);
+
+ // Endgame with opposite-colored bishops, but also other pieces. Still
+ // a bit drawish, but not as drawish as with only the two bishops.
+ else
+ sf = ScaleFactor(46 * sf / SCALE_FACTOR_NORMAL);
+ }
+ // Endings where weaker side can place his king in front of the opponent's
+ // pawns are drawish.
+ else if ( abs(eg) <= BishopValueEg
+ && ei.pi->pawn_span(strongSide) <= 1
+ && !pos.pawn_passed(~strongSide, pos.square<KING>(~strongSide)))
+ sf = ei.pi->pawn_span(strongSide) ? ScaleFactor(51) : ScaleFactor(37);
+ }
+
+ return sf;
}
} // namespace
/// evaluate() is the main evaluation function. It returns a static evaluation
-/// of the position always from the point of view of the side to move.
+/// of the position from the point of view of the side to move.
template<bool DoTrace>
Value Eval::evaluate(const Position& pos) {
assert(!pos.checkers());
EvalInfo ei;
- Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
+ 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 from the point of view of white.
+ // 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
- Material::Entry* me = Material::probe(pos);
- score += me->imbalance();
+ 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 (me->specialized_eval_exists())
- return me->evaluate(pos);
+ if (ei.me->specialized_eval_exists())
+ return ei.me->evaluate(pos);
// 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;
- init_eval_info<WHITE>(pos, ei);
- init_eval_info<BLACK>(pos, ei);
+ 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
+ // 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 squares protected by enemy pawns, or occupied
+ // 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 pieces and mobility
- score += evaluate_pieces<KNIGHT, WHITE, DoTrace>(pos, ei, mobility, mobilityArea);
- score += (mobility[WHITE] - mobility[BLACK]) * Weights[Mobility];
+ // Evaluate all pieces but king and pawns
+ score += evaluate_pieces<DoTrace>(pos, ei, mobility, mobilityArea);
+ score += mobility[WHITE] - mobility[BLACK];
- // Evaluate kings after all other pieces because we need complete attack
+ // 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);
{
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) >= 11756)
- score += (evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei)) * Weights[Space];
-
- // Scale winning side if position is more drawish than it appears
- Color strongSide = eg_value(score) > VALUE_DRAW ? WHITE : BLACK;
- ScaleFactor sf = me->scale_factor(pos, strongSide);
+ if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
+ score += evaluate_space<WHITE>(pos, ei)
+ - evaluate_space<BLACK>(pos, ei);
- // If we don't already have an unusual scale factor, check for certain
- // types of endgames, and use a lower scale for those.
- if ( 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.
- if ( pos.non_pawn_material(WHITE) == BishopValueMg
- && pos.non_pawn_material(BLACK) == BishopValueMg)
- sf = more_than_one(pos.pieces(PAWN)) ? ScaleFactor(32) : ScaleFactor(8);
-
- // 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);
- }
- // 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.square<KING>(~strongSide)))
- sf = ei.pi->pawn_span(strongSide) ? ScaleFactor(56) : ScaleFactor(38);
- }
+ // Evaluate position potential for the winning side
+ score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
- // Scale endgame by number of pawns
- int p = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK);
- int v_eg = 1 + abs(int(eg_value(score)));
- sf = ScaleFactor(std::max(sf / 2, sf - 7 * SCALE_FACTOR_NORMAL * (14 - p) / v_eg));
+ // 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(me->game_phase())
- + eg_value(score) * int(PHASE_MIDGAME - me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
+ Value v = mg_value(score) * int(ei.me->game_phase())
+ + eg_value(score) * int(PHASE_MIDGAME - ei.me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
v /= int(PHASE_MIDGAME);
- // In case of tracing add all single evaluation terms
+ // In case of tracing add all remaining individual evaluation terms
if (DoTrace)
{
Trace::add(MATERIAL, pos.psq_score());
- Trace::add(IMBALANCE, me->imbalance());
+ Trace::add(IMBALANCE, ei.me->imbalance());
Trace::add(PAWN, ei.pi->pawns_score());
- Trace::add(MOBILITY, mobility[WHITE] * Weights[Mobility]
- , mobility[BLACK] * Weights[Mobility]);
- Trace::add(SPACE, evaluate_space<WHITE>(pos, ei) * Weights[Space]
- , evaluate_space<BLACK>(pos, ei) * Weights[Space]);
+ Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
+ 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