2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
30 #include "ucioption.h"
34 // Struct EvalInfo contains various information computed and collected
35 // by the evaluation functions.
38 // Pointers to material and pawn hash table entries
42 // attackedBy[color][piece type] is a bitboard representing all squares
43 // attacked by a given color and piece type, attackedBy[color][0] contains
44 // all squares attacked by the given color.
45 Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
47 // kingRing[color] is the zone around the king which is considered
48 // by the king safety evaluation. This consists of the squares directly
49 // adjacent to the king, and the three (or two, for a king on an edge file)
50 // squares two ranks in front of the king. For instance, if black's king
51 // is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
52 // f7, g7, h7, f6, g6 and h6.
53 Bitboard kingRing[COLOR_NB];
55 // kingAttackersCount[color] is the number of pieces of the given color
56 // which attack a square in the kingRing of the enemy king.
57 int kingAttackersCount[COLOR_NB];
59 // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
60 // given color which attack a square in the kingRing of the enemy king. The
61 // weights of the individual piece types are given by the variables
62 // QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
63 // KnightAttackWeight in evaluate.cpp
64 int kingAttackersWeight[COLOR_NB];
66 // kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
67 // directly adjacent to the king of the given color. Pieces which attack
68 // more than one square are counted multiple times. For instance, if black's
69 // king is on g8 and there's a white knight on g5, this knight adds
70 // 2 to kingAdjacentZoneAttacksCount[BLACK].
71 int kingAdjacentZoneAttacksCount[COLOR_NB];
74 // Evaluation grain size, must be a power of 2
75 const int GrainSize = 8;
77 // Evaluation weights, initialized from UCI options
78 enum { Mobility, PassedPawns, Space, KingDangerUs, KingDangerThem };
82 #define S(mg, eg) make_score(mg, eg)
84 // Internal evaluation weights. These are applied on top of the evaluation
85 // weights read from UCI parameters. The purpose is to be able to change
86 // the evaluation weights while keeping the default values of the UCI
87 // parameters at 100, which looks prettier.
89 // Values modified by Joona Kiiski
90 const Score WeightsInternal[] = {
91 S(252, 344), S(216, 266), S(46, 0), S(247, 0), S(259, 0)
94 // MobilityBonus[PieceType][attacked] contains mobility bonuses for middle and
95 // end game, indexed by piece type and number of attacked squares not occupied
96 // by friendly pieces.
97 const Score MobilityBonus[][32] = {
99 { S(-38,-33), S(-25,-23), S(-12,-13), S( 0, -3), S(12, 7), S(25, 17), // Knights
100 S( 31, 22), S( 38, 27), S( 38, 27) },
101 { S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12), S(31, 26), S(45, 40), // Bishops
102 S( 57, 52), S( 65, 60), S( 71, 65), S(74, 69), S(76, 71), S(78, 73),
103 S( 79, 74), S( 80, 75), S( 81, 76), S(81, 76) },
104 { S(-20,-36), S(-14,-19), S( -8, -3), S(-2, 13), S( 4, 29), S(10, 46), // Rooks
105 S( 14, 62), S( 19, 79), S( 23, 95), S(26,106), S(27,111), S(28,114),
106 S( 29,116), S( 30,117), S( 31,118), S(32,118) },
107 { S(-10,-18), S( -8,-13), S( -6, -7), S(-3, -2), S(-1, 3), S( 1, 8), // Queens
108 S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
109 S( 16, 35), S( 17, 35), S( 18, 35), S(20, 35), S(20, 35), S(20, 35),
110 S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
111 S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
112 S( 20, 35), S( 20, 35) }
115 // OutpostBonus[PieceType][Square] contains outpost bonuses of knights and
116 // bishops, indexed by piece type and square (from white's point of view).
117 const Value OutpostBonus[][SQUARE_NB] = {
120 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
121 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
122 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
123 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
124 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
125 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },
127 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
128 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
129 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
130 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
131 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
132 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }
135 // ThreatBonus[attacking][attacked] contains threat bonuses according to
136 // which piece type attacks which one.
137 const Score ThreatBonus[][PIECE_TYPE_NB] = {
139 { S(0, 0), S( 7, 39), S( 0, 0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT
140 { S(0, 0), S( 7, 39), S(24, 49), S( 0, 0), S(41,100), S(41,100) }, // BISHOP
141 { S(0, 0), S( 0, 22), S(15, 49), S(15, 49), S( 0, 0), S(24, 49) }, // ROOK
142 { S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0, 0) } // QUEEN
145 // ThreatenedByPawnPenalty[PieceType] contains a penalty according to which
146 // piece type is attacked by an enemy pawn.
147 const Score ThreatenedByPawnPenalty[] = {
148 S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
153 // Bonus for having the side to move (modified by Joona Kiiski)
154 const Score Tempo = make_score(24, 11);
156 // Rooks and queens on the 7th rank
157 const Score RookOn7thBonus = make_score(3, 20);
158 const Score QueenOn7thBonus = make_score(1, 8);
160 // Rooks and queens attacking pawns on the same rank
161 const Score RookOnPawnBonus = make_score(3, 48);
162 const Score QueenOnPawnBonus = make_score(1, 40);
164 // Rooks on open files (modified by Joona Kiiski)
165 const Score RookOpenFileBonus = make_score(43, 21);
166 const Score RookHalfOpenFileBonus = make_score(19, 10);
168 // Penalty for rooks trapped inside a friendly king which has lost the
170 const Value TrappedRookPenalty = Value(180);
172 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
173 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
174 // happen in Chess960 games.
175 const Score TrappedBishopA1H1Penalty = make_score(100, 100);
177 // Penalty for an undefended bishop or knight
178 const Score UndefendedMinorPenalty = make_score(25, 10);
180 // The SpaceMask[Color] contains the area of the board which is considered
181 // by the space evaluation. In the middle game, each side is given a bonus
182 // based on how many squares inside this area are safe and available for
183 // friendly minor pieces.
184 const Bitboard SpaceMask[] = {
185 (1ULL << SQ_C2) | (1ULL << SQ_D2) | (1ULL << SQ_E2) | (1ULL << SQ_F2) |
186 (1ULL << SQ_C3) | (1ULL << SQ_D3) | (1ULL << SQ_E3) | (1ULL << SQ_F3) |
187 (1ULL << SQ_C4) | (1ULL << SQ_D4) | (1ULL << SQ_E4) | (1ULL << SQ_F4),
188 (1ULL << SQ_C7) | (1ULL << SQ_D7) | (1ULL << SQ_E7) | (1ULL << SQ_F7) |
189 (1ULL << SQ_C6) | (1ULL << SQ_D6) | (1ULL << SQ_E6) | (1ULL << SQ_F6) |
190 (1ULL << SQ_C5) | (1ULL << SQ_D5) | (1ULL << SQ_E5) | (1ULL << SQ_F5)
193 // King danger constants and variables. The king danger scores are taken
194 // from the KingDangerTable[]. Various little "meta-bonuses" measuring
195 // the strength of the enemy attack are added up into an integer, which
196 // is used as an index to KingDangerTable[].
198 // KingAttackWeights[PieceType] contains king attack weights by piece type
199 const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
201 // Bonuses for enemy's safe checks
202 const int QueenContactCheckBonus = 6;
203 const int RookContactCheckBonus = 4;
204 const int QueenCheckBonus = 3;
205 const int RookCheckBonus = 2;
206 const int BishopCheckBonus = 1;
207 const int KnightCheckBonus = 1;
209 // InitKingDanger[Square] contains penalties based on the position of the
210 // defending king, indexed by king's square (from white's point of view).
211 const int InitKingDanger[] = {
212 2, 0, 2, 5, 5, 2, 0, 2,
213 2, 2, 4, 8, 8, 4, 2, 2,
214 7, 10, 12, 12, 12, 12, 10, 7,
215 15, 15, 15, 15, 15, 15, 15, 15,
216 15, 15, 15, 15, 15, 15, 15, 15,
217 15, 15, 15, 15, 15, 15, 15, 15,
218 15, 15, 15, 15, 15, 15, 15, 15,
219 15, 15, 15, 15, 15, 15, 15, 15
222 // KingDangerTable[Color][attackUnits] contains the actual king danger
223 // weighted scores, indexed by color and by a calculated integer number.
224 Score KingDangerTable[COLOR_NB][128];
226 // TracedTerms[Color][PieceType || TracedType] contains a breakdown of the
227 // evaluation terms, used when tracing.
228 Score TracedScores[COLOR_NB][16];
229 std::stringstream TraceStream;
232 PST = 8, IMBALANCE = 9, MOBILITY = 10, THREAT = 11,
233 PASSED = 12, UNSTOPPABLE = 13, SPACE = 14, TOTAL = 15
236 // Function prototypes
238 Value do_evaluate(const Position& pos, Value& margin);
241 void init_eval_info(const Position& pos, EvalInfo& ei);
243 template<Color Us, bool Trace>
244 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility);
246 template<Color Us, bool Trace>
247 Score evaluate_king(const Position& pos, EvalInfo& ei, int16_t margins[]);
250 Score evaluate_threats(const Position& pos, EvalInfo& ei);
253 int evaluate_space(const Position& pos, EvalInfo& ei);
256 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
258 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
260 Value interpolate(const Score& v, Phase ph, ScaleFactor sf);
261 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
262 double to_cp(Value v);
263 void trace_add(int idx, Score term_w, Score term_b = SCORE_ZERO);
264 void trace_row(const char* name, int idx);
270 /// evaluate() is the main evaluation function. It always computes two
271 /// values, an endgame score and a middle game score, and interpolates
272 /// between them based on the remaining material.
274 Value evaluate(const Position& pos, Value& margin) {
275 return do_evaluate<false>(pos, margin);
279 /// init() computes evaluation weights from the corresponding UCI parameters
280 /// and setup king tables.
284 Weights[Mobility] = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
285 Weights[PassedPawns] = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
286 Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
287 Weights[KingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
288 Weights[KingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
290 // King safety is asymmetrical. Our king danger level is weighted by
291 // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
292 // If running in analysis mode, make sure we use symmetrical king safety. We
293 // do this by replacing both Weights[kingDangerUs] and Weights[kingDangerThem]
295 if (Options["UCI_AnalyseMode"])
296 Weights[KingDangerUs] = Weights[KingDangerThem] = (Weights[KingDangerUs] + Weights[KingDangerThem]) / 2;
298 const int MaxSlope = 30;
299 const int Peak = 1280;
301 for (int t = 0, i = 1; i < 100; i++)
303 t = std::min(Peak, std::min(int(0.4 * i * i), t + MaxSlope));
305 KingDangerTable[1][i] = apply_weight(make_score(t, 0), Weights[KingDangerUs]);
306 KingDangerTable[0][i] = apply_weight(make_score(t, 0), Weights[KingDangerThem]);
311 /// trace() is like evaluate() but instead of a value returns a string suitable
312 /// to be print on stdout with the detailed descriptions and values of each
313 /// evaluation term. Used mainly for debugging.
315 std::string trace(const Position& pos) {
320 Search::RootColor = pos.side_to_move();
323 TraceStream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
324 memset(TracedScores, 0, 2 * 16 * sizeof(Score));
326 do_evaluate<true>(pos, margin);
328 totals = TraceStream.str();
331 TraceStream << std::setw(21) << "Eval term " << "| White | Black | Total \n"
332 << " | MG EG | MG EG | MG EG \n"
333 << "---------------------+-------------+-------------+---------------\n";
335 trace_row("Material, PST, Tempo", PST);
336 trace_row("Material imbalance", IMBALANCE);
337 trace_row("Pawns", PAWN);
338 trace_row("Knights", KNIGHT);
339 trace_row("Bishops", BISHOP);
340 trace_row("Rooks", ROOK);
341 trace_row("Queens", QUEEN);
342 trace_row("Mobility", MOBILITY);
343 trace_row("King safety", KING);
344 trace_row("Threats", THREAT);
345 trace_row("Passed pawns", PASSED);
346 trace_row("Unstoppable pawns", UNSTOPPABLE);
347 trace_row("Space", SPACE);
349 TraceStream << "---------------------+-------------+-------------+---------------\n";
350 trace_row("Total", TOTAL);
351 TraceStream << totals;
353 return TraceStream.str();
362 Value do_evaluate(const Position& pos, Value& margin) {
364 assert(!pos.checkers());
367 Score score, mobilityWhite, mobilityBlack;
370 Thread* th = pos.this_thread();
371 Eval::Entry* e = th->evalTable[key];
373 // If e->key matches the position's hash key, it means that we have analysed
374 // this node before, and we can simply return the information we found the last
375 // time instead of recomputing it.
378 margin = Value(e->margins[pos.side_to_move()]);
382 // Otherwise we overwrite current content with this node info.
385 // margins[] store the uncertainty estimation of position's evaluation
386 // that typically is used by the search for pruning decisions.
387 e->margins[WHITE] = e->margins[BLACK] = VALUE_ZERO;
389 // Initialize score by reading the incrementally updated scores included
390 // in the position object (material + piece square tables) and adding
391 // Tempo bonus. Score is computed from the point of view of white.
392 score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
394 // Probe the material hash table
395 ei.mi = Material::probe(pos, th->materialTable, th->endgames);
396 score += ei.mi->material_value();
398 // If we have a specialized evaluation function for the current material
399 // configuration, call it and return.
400 if (ei.mi->specialized_eval_exists())
403 e->value = ei.mi->evaluate(pos);
407 // Probe the pawn hash table
408 ei.pi = Pawns::probe(pos, th->pawnsTable);
409 score += ei.pi->pawns_value();
411 // Initialize attack and king safety bitboards
412 init_eval_info<WHITE>(pos, ei);
413 init_eval_info<BLACK>(pos, ei);
415 // Evaluate pieces and mobility
416 score += evaluate_pieces_of_color<WHITE, Trace>(pos, ei, mobilityWhite)
417 - evaluate_pieces_of_color<BLACK, Trace>(pos, ei, mobilityBlack);
419 score += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
421 // Evaluate kings after all other pieces because we need complete attack
422 // information when computing the king safety evaluation.
423 score += evaluate_king<WHITE, Trace>(pos, ei, e->margins)
424 - evaluate_king<BLACK, Trace>(pos, ei, e->margins);
426 // Evaluate tactical threats, we need full attack information including king
427 score += evaluate_threats<WHITE>(pos, ei)
428 - evaluate_threats<BLACK>(pos, ei);
430 // Evaluate passed pawns, we need full attack information including king
431 score += evaluate_passed_pawns<WHITE>(pos, ei)
432 - evaluate_passed_pawns<BLACK>(pos, ei);
434 // If one side has only a king, check whether exists any unstoppable passed pawn
435 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
436 score += evaluate_unstoppable_pawns(pos, ei);
438 // Evaluate space for both sides, only in middle-game.
439 if (ei.mi->space_weight())
441 int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
442 score += apply_weight(make_score(s * ei.mi->space_weight(), 0), Weights[Space]);
445 // Scale winning side if position is more drawish that what it appears
446 ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
447 : ei.mi->scale_factor(pos, BLACK);
449 // If we don't already have an unusual scale factor, check for opposite
450 // colored bishop endgames, and use a lower scale for those.
451 if ( ei.mi->game_phase() < PHASE_MIDGAME
452 && pos.opposite_bishops()
453 && sf == SCALE_FACTOR_NORMAL)
455 // Only the two bishops ?
456 if ( pos.non_pawn_material(WHITE) == BishopValueMg
457 && pos.non_pawn_material(BLACK) == BishopValueMg)
459 // Check for KBP vs KB with only a single pawn that is almost
460 // certainly a draw or at least two pawns.
461 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
462 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
465 // Endgame with opposite-colored bishops, but also other pieces. Still
466 // a bit drawish, but not as drawish as with only the two bishops.
467 sf = ScaleFactor(50);
470 margin = Value(e->margins[pos.side_to_move()]);
471 Value v = interpolate(score, ei.mi->game_phase(), sf);
473 // In case of tracing add all single evaluation contributions for both white and black
476 trace_add(PST, pos.psq_score());
477 trace_add(IMBALANCE, ei.mi->material_value());
478 trace_add(PAWN, ei.pi->pawns_value());
479 trace_add(MOBILITY, apply_weight(mobilityWhite, Weights[Mobility]), apply_weight(mobilityBlack, Weights[Mobility]));
480 trace_add(THREAT, evaluate_threats<WHITE>(pos, ei), evaluate_threats<BLACK>(pos, ei));
481 trace_add(PASSED, evaluate_passed_pawns<WHITE>(pos, ei), evaluate_passed_pawns<BLACK>(pos, ei));
482 trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei));
483 Score w = make_score(ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei), 0);
484 Score b = make_score(ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei), 0);
485 trace_add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
486 trace_add(TOTAL, score);
487 TraceStream << "\nUncertainty margin: White: " << to_cp(Value(e->margins[WHITE]))
488 << ", Black: " << to_cp(Value(e->margins[BLACK]))
489 << "\nScaling: " << std::noshowpos
490 << std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
491 << std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
492 << std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
493 << "Total evaluation: " << to_cp(v);
496 return e->value = pos.side_to_move() == WHITE ? v : -v;
500 // init_eval_info() initializes king bitboards for given color adding
501 // pawn attacks. To be done at the beginning of the evaluation.
504 void init_eval_info(const Position& pos, EvalInfo& ei) {
506 const Color Them = (Us == WHITE ? BLACK : WHITE);
508 Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
509 ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
511 // Init king safety tables only if we are going to use them
512 if ( pos.piece_count(Us, QUEEN)
513 && pos.non_pawn_material(Us) >= QueenValueMg + RookValueMg)
515 ei.kingRing[Them] = (b | (Us == WHITE ? b >> 8 : b << 8));
516 b &= ei.attackedBy[Us][PAWN];
517 ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
518 ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
520 ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
524 // evaluate_outposts() evaluates bishop and knight outposts squares
526 template<PieceType Piece, Color Us>
527 Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
529 const Color Them = (Us == WHITE ? BLACK : WHITE);
531 assert (Piece == BISHOP || Piece == KNIGHT);
533 // Initial bonus based on square
534 Value bonus = OutpostBonus[Piece == BISHOP][relative_square(Us, s)];
536 // Increase bonus if supported by pawn, especially if the opponent has
537 // no minor piece which can exchange the outpost piece.
538 if (bonus && (ei.attackedBy[Us][PAWN] & s))
540 if ( !pos.pieces(Them, KNIGHT)
541 && !(same_color_squares(s) & pos.pieces(Them, BISHOP)))
542 bonus += bonus + bonus / 2;
546 return make_score(bonus, bonus);
550 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
552 template<PieceType Piece, Color Us, bool Trace>
553 Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
559 Score score = SCORE_ZERO;
561 const Color Them = (Us == WHITE ? BLACK : WHITE);
562 const Square* pl = pos.piece_list(Us, Piece);
564 ei.attackedBy[Us][Piece] = 0;
566 while ((s = *pl++) != SQ_NONE)
568 // Find attacked squares, including x-ray attacks for bishops and rooks
569 if (Piece == KNIGHT || Piece == QUEEN)
570 b = pos.attacks_from<Piece>(s);
571 else if (Piece == BISHOP)
572 b = attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN));
573 else if (Piece == ROOK)
574 b = attacks_bb<ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN));
578 ei.attackedBy[Us][Piece] |= b;
580 if (b & ei.kingRing[Them])
582 ei.kingAttackersCount[Us]++;
583 ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
584 Bitboard bb = (b & ei.attackedBy[Them][KING]);
586 ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
589 mob = (Piece != QUEEN ? popcount<Max15>(b & mobilityArea)
590 : popcount<Full >(b & mobilityArea));
592 mobility += MobilityBonus[Piece][mob];
594 // Add a bonus if a slider is pinning an enemy piece
595 if ( (Piece == BISHOP || Piece == ROOK || Piece == QUEEN)
596 && (PseudoAttacks[Piece][pos.king_square(Them)] & s))
598 b = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
602 if (!more_than_one(b) && (b & pos.pieces(Them)))
603 score += ThreatBonus[Piece][type_of(pos.piece_on(lsb(b)))];
606 // Decrease score if we are attacked by an enemy pawn. Remaining part
607 // of threat evaluation must be done later when we have full attack info.
608 if (ei.attackedBy[Them][PAWN] & s)
609 score -= ThreatenedByPawnPenalty[Piece];
611 // Bishop and knight outposts squares
612 if ( (Piece == BISHOP || Piece == KNIGHT)
613 && !(pos.pieces(Them, PAWN) & attack_span_mask(Us, s)))
614 score += evaluate_outposts<Piece, Us>(pos, ei, s);
616 if ((Piece == ROOK || Piece == QUEEN) && relative_rank(Us, s) >= RANK_5)
618 // Major piece on 7th rank
619 if ( relative_rank(Us, s) == RANK_7
620 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
621 score += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
623 // Major piece attacking pawns on the same rank
624 Bitboard pawns = pos.pieces(Them, PAWN) & rank_bb(s);
626 score += (Piece == ROOK ? RookOnPawnBonus
627 : QueenOnPawnBonus) * popcount<Max15>(pawns);
630 // Special extra evaluation for bishops
631 if (Piece == BISHOP && pos.is_chess960())
633 // An important Chess960 pattern: A cornered bishop blocked by
634 // a friendly pawn diagonally in front of it is a very serious
635 // problem, especially when that pawn is also blocked.
636 if (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1))
638 Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
639 if (pos.piece_on(s + d) == make_piece(Us, PAWN))
641 if (!pos.is_empty(s + d + pawn_push(Us)))
642 score -= 2*TrappedBishopA1H1Penalty;
643 else if (pos.piece_on(s + 2*d) == make_piece(Us, PAWN))
644 score -= TrappedBishopA1H1Penalty;
646 score -= TrappedBishopA1H1Penalty / 2;
651 // Special extra evaluation for rooks
654 // Open and half-open files
656 if (ei.pi->file_is_half_open(Us, f))
658 if (ei.pi->file_is_half_open(Them, f))
659 score += RookOpenFileBonus;
661 score += RookHalfOpenFileBonus;
664 // Penalize rooks which are trapped inside a king. Penalize more if
665 // king has lost right to castle.
666 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
669 ksq = pos.king_square(Us);
671 if ( file_of(ksq) >= FILE_E
672 && file_of(s) > file_of(ksq)
673 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
675 // Is there a half-open file between the king and the edge of the board?
676 if (!ei.pi->has_open_file_to_right(Us, file_of(ksq)))
677 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
678 : (TrappedRookPenalty - mob * 16), 0);
680 else if ( file_of(ksq) <= FILE_D
681 && file_of(s) < file_of(ksq)
682 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
684 // Is there a half-open file between the king and the edge of the board?
685 if (!ei.pi->has_open_file_to_left(Us, file_of(ksq)))
686 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
687 : (TrappedRookPenalty - mob * 16), 0);
693 TracedScores[Us][Piece] = score;
699 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
700 // and the type of attacked one.
703 Score evaluate_threats(const Position& pos, EvalInfo& ei) {
705 const Color Them = (Us == WHITE ? BLACK : WHITE);
707 Bitboard b, undefendedMinors, weakEnemies;
708 Score score = SCORE_ZERO;
710 // Undefended minors get penalized even if not under attack
711 undefendedMinors = pos.pieces(Them)
712 & (pos.pieces(BISHOP) | pos.pieces(KNIGHT))
713 & ~ei.attackedBy[Them][0];
715 if (undefendedMinors)
716 score += more_than_one(undefendedMinors) ? UndefendedMinorPenalty * 2
717 : UndefendedMinorPenalty;
719 // Enemy pieces not defended by a pawn and under our attack
720 weakEnemies = pos.pieces(Them)
721 & ~ei.attackedBy[Them][PAWN]
722 & ei.attackedBy[Us][0];
727 // Add bonus according to type of attacked enemy piece and to the
728 // type of attacking piece, from knights to queens. Kings are not
729 // considered because are already handled in king evaluation.
730 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
732 b = ei.attackedBy[Us][pt1] & weakEnemies;
734 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
735 if (b & pos.pieces(pt2))
736 score += ThreatBonus[pt1][pt2];
742 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
743 // pieces of a given color.
745 template<Color Us, bool Trace>
746 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
748 const Color Them = (Us == WHITE ? BLACK : WHITE);
750 Score score = mobility = SCORE_ZERO;
752 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
753 const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces(Us));
755 score += evaluate_pieces<KNIGHT, Us, Trace>(pos, ei, mobility, mobilityArea);
756 score += evaluate_pieces<BISHOP, Us, Trace>(pos, ei, mobility, mobilityArea);
757 score += evaluate_pieces<ROOK, Us, Trace>(pos, ei, mobility, mobilityArea);
758 score += evaluate_pieces<QUEEN, Us, Trace>(pos, ei, mobility, mobilityArea);
760 // Sum up all attacked squares
761 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
762 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
763 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
768 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
770 template<Color Us, bool Trace>
771 Score evaluate_king(const Position& pos, EvalInfo& ei, int16_t margins[]) {
773 const Color Them = (Us == WHITE ? BLACK : WHITE);
775 Bitboard undefended, b, b1, b2, safe;
777 const Square ksq = pos.king_square(Us);
779 // King shelter and enemy pawns storm
780 Score score = ei.pi->king_safety<Us>(pos, ksq);
782 // King safety. This is quite complicated, and is almost certainly far
783 // from optimally tuned.
784 if ( ei.kingAttackersCount[Them] >= 2
785 && ei.kingAdjacentZoneAttacksCount[Them])
787 // Find the attacked squares around the king which has no defenders
788 // apart from the king itself
789 undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
790 undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
791 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
792 | ei.attackedBy[Us][QUEEN]);
794 // Initialize the 'attackUnits' variable, which is used later on as an
795 // index to the KingDangerTable[] array. The initial value is based on
796 // the number and types of the enemy's attacking pieces, the number of
797 // attacked and undefended squares around our king, the square of the
798 // king, and the quality of the pawn shelter.
799 attackUnits = std::min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
800 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
801 + InitKingDanger[relative_square(Us, ksq)]
802 - mg_value(score) / 32;
804 // Analyse enemy's safe queen contact checks. First find undefended
805 // squares around the king attacked by enemy queen...
806 b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
809 // ...then remove squares not supported by another enemy piece
810 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
811 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
813 attackUnits += QueenContactCheckBonus
815 * (Them == pos.side_to_move() ? 2 : 1);
818 // Analyse enemy's safe rook contact checks. First find undefended
819 // squares around the king attacked by enemy rooks...
820 b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
822 // Consider only squares where the enemy rook gives check
823 b &= PseudoAttacks[ROOK][ksq];
827 // ...then remove squares not supported by another enemy piece
828 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
829 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
831 attackUnits += RookContactCheckBonus
833 * (Them == pos.side_to_move() ? 2 : 1);
836 // Analyse enemy's safe distance checks for sliders and knights
837 safe = ~(pos.pieces(Them) | ei.attackedBy[Us][0]);
839 b1 = pos.attacks_from<ROOK>(ksq) & safe;
840 b2 = pos.attacks_from<BISHOP>(ksq) & safe;
842 // Enemy queen safe checks
843 b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
845 attackUnits += QueenCheckBonus * popcount<Max15>(b);
847 // Enemy rooks safe checks
848 b = b1 & ei.attackedBy[Them][ROOK];
850 attackUnits += RookCheckBonus * popcount<Max15>(b);
852 // Enemy bishops safe checks
853 b = b2 & ei.attackedBy[Them][BISHOP];
855 attackUnits += BishopCheckBonus * popcount<Max15>(b);
857 // Enemy knights safe checks
858 b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
860 attackUnits += KnightCheckBonus * popcount<Max15>(b);
862 // To index KingDangerTable[] attackUnits must be in [0, 99] range
863 attackUnits = std::min(99, std::max(0, attackUnits));
865 // Finally, extract the king danger score from the KingDangerTable[]
866 // array and subtract the score from evaluation. Set also margins[]
867 // value that will be used for pruning because this value can sometimes
868 // be very big, and so capturing a single attacking piece can therefore
869 // result in a score change far bigger than the value of the captured piece.
870 score -= KingDangerTable[Us == Search::RootColor][attackUnits];
871 margins[Us] += int16_t(mg_value(KingDangerTable[Us == Search::RootColor][attackUnits]));
875 TracedScores[Us][KING] = score;
881 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
884 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
886 const Color Them = (Us == WHITE ? BLACK : WHITE);
888 Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
889 Score score = SCORE_ZERO;
891 b = ei.pi->passed_pawns(Us);
897 Square s = pop_lsb(&b);
899 assert(pos.pawn_is_passed(Us, s));
901 int r = int(relative_rank(Us, s) - RANK_2);
902 int rr = r * (r - 1);
904 // Base bonus based on rank
905 Value mbonus = Value(20 * rr);
906 Value ebonus = Value(10 * (rr + r + 1));
910 Square blockSq = s + pawn_push(Us);
912 // Adjust bonus based on kings proximity
913 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr);
914 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 2 * rr);
916 // If blockSq is not the queening square then consider also a second push
917 if (rank_of(blockSq) != (Us == WHITE ? RANK_8 : RANK_1))
918 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
920 // If the pawn is free to advance, increase bonus
921 if (pos.is_empty(blockSq))
923 squaresToQueen = forward_bb(Us, s);
924 defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
926 // If there is an enemy rook or queen attacking the pawn from behind,
927 // add all X-ray attacks by the rook or queen. Otherwise consider only
928 // the squares in the pawn's path attacked or occupied by the enemy.
929 if ( (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN))
930 && (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN) & pos.attacks_from<ROOK>(s)))
931 unsafeSquares = squaresToQueen;
933 unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces(Them));
935 // If there aren't enemy attacks or pieces along the path to queen give
936 // huge bonus. Even bigger if we protect the pawn's path.
938 ebonus += Value(rr * (squaresToQueen == defendedSquares ? 17 : 15));
940 // OK, there are enemy attacks or pieces (but not pawns). Are those
941 // squares which are attacked by the enemy also attacked by us ?
942 // If yes, big bonus (but smaller than when there are no enemy attacks),
943 // if no, somewhat smaller bonus.
944 ebonus += Value(rr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
948 // Increase the bonus if the passed pawn is supported by a friendly pawn
949 // on the same rank and a bit smaller if it's on the previous rank.
950 supportingPawns = pos.pieces(Us, PAWN) & adjacent_files_bb(file_of(s));
951 if (supportingPawns & rank_bb(s))
952 ebonus += Value(r * 20);
954 else if (supportingPawns & rank_bb(s - pawn_push(Us)))
955 ebonus += Value(r * 12);
957 // Rook pawns are a special case: They are sometimes worse, and
958 // sometimes better than other passed pawns. It is difficult to find
959 // good rules for determining whether they are good or bad. For now,
960 // we try the following: Increase the value for rook pawns if the
961 // other side has no pieces apart from a knight, and decrease the
962 // value if the other side has a rook or queen.
963 if (file_of(s) == FILE_A || file_of(s) == FILE_H)
965 if (pos.non_pawn_material(Them) <= KnightValueMg)
966 ebonus += ebonus / 4;
967 else if (pos.pieces(Them, ROOK, QUEEN))
968 ebonus -= ebonus / 4;
970 score += make_score(mbonus, ebonus);
974 // Add the scores to the middle game and endgame eval
975 return apply_weight(score, Weights[PassedPawns]);
979 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides, this is quite
980 // conservative and returns a winning score only when we are very sure that the pawn is winning.
982 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
984 Bitboard b, b2, blockers, supporters, queeningPath, candidates;
985 Square s, blockSq, queeningSquare;
986 Color c, winnerSide, loserSide;
987 bool pathDefended, opposed;
988 int pliesToGo, movesToGo, oppMovesToGo, sacptg, blockersCount, minKingDist, kingptg, d;
989 int pliesToQueen[] = { 256, 256 };
991 // Step 1. Hunt for unstoppable passed pawns. If we find at least one,
992 // record how many plies are required for promotion.
993 for (c = WHITE; c <= BLACK; c++)
995 // Skip if other side has non-pawn pieces
996 if (pos.non_pawn_material(~c))
999 b = ei.pi->passed_pawns(c);
1004 queeningSquare = relative_square(c, file_of(s) | RANK_8);
1005 queeningPath = forward_bb(c, s);
1007 // Compute plies to queening and check direct advancement
1008 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
1009 oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
1010 pathDefended = ((ei.attackedBy[c][0] & queeningPath) == queeningPath);
1012 if (movesToGo >= oppMovesToGo && !pathDefended)
1015 // Opponent king cannot block because path is defended and position
1016 // is not in check. So only friendly pieces can be blockers.
1017 assert(!pos.checkers());
1018 assert((queeningPath & pos.pieces()) == (queeningPath & pos.pieces(c)));
1020 // Add moves needed to free the path from friendly pieces and retest condition
1021 movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
1023 if (movesToGo >= oppMovesToGo && !pathDefended)
1026 pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
1027 pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
1031 // Step 2. If either side cannot promote at least three plies before the other side then situation
1032 // becomes too complex and we give up. Otherwise we determine the possibly "winning side"
1033 if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3)
1036 winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
1037 loserSide = ~winnerSide;
1039 // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
1040 b = candidates = pos.pieces(loserSide, PAWN);
1046 // Compute plies from queening
1047 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
1048 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
1049 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
1051 // Check if (without even considering any obstacles) we're too far away or doubled
1052 if ( pliesToQueen[winnerSide] + 3 <= pliesToGo
1053 || (forward_bb(loserSide, s) & pos.pieces(loserSide, PAWN)))
1057 // If any candidate is already a passed pawn it _may_ promote in time. We give up.
1058 if (candidates & ei.pi->passed_pawns(loserSide))
1061 // Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
1067 sacptg = blockersCount = 0;
1068 minKingDist = kingptg = 256;
1070 // Compute plies from queening
1071 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
1072 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
1073 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
1075 // Generate list of blocking pawns and supporters
1076 supporters = adjacent_files_bb(file_of(s)) & candidates;
1077 opposed = forward_bb(loserSide, s) & pos.pieces(winnerSide, PAWN);
1078 blockers = passed_pawn_mask(loserSide, s) & pos.pieces(winnerSide, PAWN);
1082 // How many plies does it take to remove all the blocking pawns?
1085 blockSq = pop_lsb(&blockers);
1088 // Check pawns that can give support to overcome obstacle, for instance
1089 // black pawns: a4, b4 white: b2 then pawn in b4 is giving support.
1092 b2 = supporters & in_front_bb(winnerSide, blockSq + pawn_push(winnerSide));
1094 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1096 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1097 movesToGo = std::min(movesToGo, d);
1101 // Check pawns that can be sacrificed against the blocking pawn
1102 b2 = attack_span_mask(winnerSide, blockSq) & candidates & ~(1ULL << s);
1104 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1106 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1107 movesToGo = std::min(movesToGo, d);
1110 // If obstacle can be destroyed with an immediate pawn exchange / sacrifice,
1111 // it's not a real obstacle and we have nothing to add to pliesToGo.
1115 // Plies needed to sacrifice against all the blocking pawns
1116 sacptg += movesToGo * 2;
1119 // Plies needed for the king to capture all the blocking pawns
1120 d = square_distance(pos.king_square(loserSide), blockSq);
1121 minKingDist = std::min(minKingDist, d);
1122 kingptg = (minKingDist + blockersCount) * 2;
1125 // Check if pawn sacrifice plan _may_ save the day
1126 if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
1129 // Check if king capture plan _may_ save the day (contains some false positives)
1130 if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
1134 // Winning pawn is unstoppable and will promote as first, return big score
1135 Score score = make_score(0, (Value) 1280 - 32 * pliesToQueen[winnerSide]);
1136 return winnerSide == WHITE ? score : -score;
1140 // evaluate_space() computes the space evaluation for a given side. The
1141 // space evaluation is a simple bonus based on the number of safe squares
1142 // available for minor pieces on the central four files on ranks 2--4. Safe
1143 // squares one, two or three squares behind a friendly pawn are counted
1144 // twice. Finally, the space bonus is scaled by a weight taken from the
1145 // material hash table. The aim is to improve play on game opening.
1147 int evaluate_space(const Position& pos, EvalInfo& ei) {
1149 const Color Them = (Us == WHITE ? BLACK : WHITE);
1151 // Find the safe squares for our pieces inside the area defined by
1152 // SpaceMask[]. A square is unsafe if it is attacked by an enemy
1153 // pawn, or if it is undefended and attacked by an enemy piece.
1154 Bitboard safe = SpaceMask[Us]
1155 & ~pos.pieces(Us, PAWN)
1156 & ~ei.attackedBy[Them][PAWN]
1157 & (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
1159 // Find all squares which are at most three squares behind some friendly pawn
1160 Bitboard behind = pos.pieces(Us, PAWN);
1161 behind |= (Us == WHITE ? behind >> 8 : behind << 8);
1162 behind |= (Us == WHITE ? behind >> 16 : behind << 16);
1164 return popcount<Max15>(safe) + popcount<Max15>(behind & safe);
1168 // interpolate() interpolates between a middle game and an endgame score,
1169 // based on game phase. It also scales the return value by a ScaleFactor array.
1171 Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {
1173 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1174 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1175 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1177 int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
1178 int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
1179 return Value((result + GrainSize / 2) & ~(GrainSize - 1));
1183 // weight_option() computes the value of an evaluation weight, by combining
1184 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1186 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1188 // Scale option value from 100 to 256
1189 int mg = Options[mgOpt] * 256 / 100;
1190 int eg = Options[egOpt] * 256 / 100;
1192 return apply_weight(make_score(mg, eg), internalWeight);
1196 // A couple of little helpers used by tracing code, to_cp() converts a value to
1197 // a double in centipawns scale, trace_add() stores white and black scores.
1199 double to_cp(Value v) { return double(v) / double(PawnValueMg); }
1201 void trace_add(int idx, Score wScore, Score bScore) {
1203 TracedScores[WHITE][idx] = wScore;
1204 TracedScores[BLACK][idx] = bScore;
1208 // trace_row() is an helper function used by tracing code to register the
1209 // values of a single evaluation term.
1211 void trace_row(const char* name, int idx) {
1213 Score wScore = TracedScores[WHITE][idx];
1214 Score bScore = TracedScores[BLACK][idx];
1217 case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
1218 TraceStream << std::setw(20) << name << " | --- --- | --- --- | "
1219 << std::setw(6) << to_cp(mg_value(wScore)) << " "
1220 << std::setw(6) << to_cp(eg_value(wScore)) << " \n";
1223 TraceStream << std::setw(20) << name << " | " << std::noshowpos
1224 << std::setw(5) << to_cp(mg_value(wScore)) << " "
1225 << std::setw(5) << to_cp(eg_value(wScore)) << " | "
1226 << std::setw(5) << to_cp(mg_value(bScore)) << " "
1227 << std::setw(5) << to_cp(eg_value(bScore)) << " | "
1229 << std::setw(6) << to_cp(mg_value(wScore - bScore)) << " "
1230 << std::setw(6) << to_cp(eg_value(wScore - bScore)) << " \n";