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, Value 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 Value margins[COLOR_NB];
368 Score score, mobilityWhite, mobilityBlack;
369 Thread* th = pos.this_thread();
371 // margins[] store the uncertainty estimation of position's evaluation
372 // that typically is used by the search for pruning decisions.
373 margins[WHITE] = margins[BLACK] = VALUE_ZERO;
375 // Initialize score by reading the incrementally updated scores included
376 // in the position object (material + piece square tables) and adding
377 // Tempo bonus. Score is computed from the point of view of white.
378 score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
380 // Probe the material hash table
381 ei.mi = Material::probe(pos, th->materialTable, th->endgames);
382 score += ei.mi->material_value();
384 // If we have a specialized evaluation function for the current material
385 // configuration, call it and return.
386 if (ei.mi->specialized_eval_exists())
389 return ei.mi->evaluate(pos);
392 // Probe the pawn hash table
393 ei.pi = Pawns::probe(pos, th->pawnsTable);
394 score += ei.pi->pawns_value();
396 // Initialize attack and king safety bitboards
397 init_eval_info<WHITE>(pos, ei);
398 init_eval_info<BLACK>(pos, ei);
400 // Evaluate pieces and mobility
401 score += evaluate_pieces_of_color<WHITE, Trace>(pos, ei, mobilityWhite)
402 - evaluate_pieces_of_color<BLACK, Trace>(pos, ei, mobilityBlack);
404 score += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
406 // Evaluate kings after all other pieces because we need complete attack
407 // information when computing the king safety evaluation.
408 score += evaluate_king<WHITE, Trace>(pos, ei, margins)
409 - evaluate_king<BLACK, Trace>(pos, ei, margins);
411 // Evaluate tactical threats, we need full attack information including king
412 score += evaluate_threats<WHITE>(pos, ei)
413 - evaluate_threats<BLACK>(pos, ei);
415 // Evaluate passed pawns, we need full attack information including king
416 score += evaluate_passed_pawns<WHITE>(pos, ei)
417 - evaluate_passed_pawns<BLACK>(pos, ei);
419 // If one side has only a king, check whether exists any unstoppable passed pawn
420 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
421 score += evaluate_unstoppable_pawns(pos, ei);
423 // Evaluate space for both sides, only in middle-game.
424 if (ei.mi->space_weight())
426 int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
427 score += apply_weight(make_score(s * ei.mi->space_weight(), 0), Weights[Space]);
430 // Scale winning side if position is more drawish that what it appears
431 ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
432 : ei.mi->scale_factor(pos, BLACK);
434 // If we don't already have an unusual scale factor, check for opposite
435 // colored bishop endgames, and use a lower scale for those.
436 if ( ei.mi->game_phase() < PHASE_MIDGAME
437 && pos.opposite_bishops()
438 && sf == SCALE_FACTOR_NORMAL)
440 // Only the two bishops ?
441 if ( pos.non_pawn_material(WHITE) == BishopValueMg
442 && pos.non_pawn_material(BLACK) == BishopValueMg)
444 // Check for KBP vs KB with only a single pawn that is almost
445 // certainly a draw or at least two pawns.
446 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
447 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
450 // Endgame with opposite-colored bishops, but also other pieces. Still
451 // a bit drawish, but not as drawish as with only the two bishops.
452 sf = ScaleFactor(50);
455 margin = margins[pos.side_to_move()];
456 Value v = interpolate(score, ei.mi->game_phase(), sf);
458 // In case of tracing add all single evaluation contributions for both white and black
461 trace_add(PST, pos.psq_score());
462 trace_add(IMBALANCE, ei.mi->material_value());
463 trace_add(PAWN, ei.pi->pawns_value());
464 trace_add(MOBILITY, apply_weight(mobilityWhite, Weights[Mobility]), apply_weight(mobilityBlack, Weights[Mobility]));
465 trace_add(THREAT, evaluate_threats<WHITE>(pos, ei), evaluate_threats<BLACK>(pos, ei));
466 trace_add(PASSED, evaluate_passed_pawns<WHITE>(pos, ei), evaluate_passed_pawns<BLACK>(pos, ei));
467 trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei));
468 Score w = make_score(ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei), 0);
469 Score b = make_score(ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei), 0);
470 trace_add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
471 trace_add(TOTAL, score);
472 TraceStream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
473 << ", Black: " << to_cp(margins[BLACK])
474 << "\nScaling: " << std::noshowpos
475 << std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
476 << std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
477 << std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
478 << "Total evaluation: " << to_cp(v);
481 return pos.side_to_move() == WHITE ? v : -v;
485 // init_eval_info() initializes king bitboards for given color adding
486 // pawn attacks. To be done at the beginning of the evaluation.
489 void init_eval_info(const Position& pos, EvalInfo& ei) {
491 const Color Them = (Us == WHITE ? BLACK : WHITE);
493 Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
494 ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
496 // Init king safety tables only if we are going to use them
497 if ( pos.piece_count(Us, QUEEN)
498 && pos.non_pawn_material(Us) >= QueenValueMg + RookValueMg)
500 ei.kingRing[Them] = (b | (Us == WHITE ? b >> 8 : b << 8));
501 b &= ei.attackedBy[Us][PAWN];
502 ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
503 ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
505 ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
509 // evaluate_outposts() evaluates bishop and knight outposts squares
511 template<PieceType Piece, Color Us>
512 Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
514 const Color Them = (Us == WHITE ? BLACK : WHITE);
516 assert (Piece == BISHOP || Piece == KNIGHT);
518 // Initial bonus based on square
519 Value bonus = OutpostBonus[Piece == BISHOP][relative_square(Us, s)];
521 // Increase bonus if supported by pawn, especially if the opponent has
522 // no minor piece which can exchange the outpost piece.
523 if (bonus && (ei.attackedBy[Us][PAWN] & s))
525 if ( !pos.pieces(Them, KNIGHT)
526 && !(same_color_squares(s) & pos.pieces(Them, BISHOP)))
527 bonus += bonus + bonus / 2;
531 return make_score(bonus, bonus);
535 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
537 template<PieceType Piece, Color Us, bool Trace>
538 Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
544 Score score = SCORE_ZERO;
546 const Color Them = (Us == WHITE ? BLACK : WHITE);
547 const Square* pl = pos.piece_list(Us, Piece);
549 ei.attackedBy[Us][Piece] = 0;
551 while ((s = *pl++) != SQ_NONE)
553 // Find attacked squares, including x-ray attacks for bishops and rooks
554 if (Piece == KNIGHT || Piece == QUEEN)
555 b = pos.attacks_from<Piece>(s);
556 else if (Piece == BISHOP)
557 b = attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN));
558 else if (Piece == ROOK)
559 b = attacks_bb<ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN));
563 ei.attackedBy[Us][Piece] |= b;
565 if (b & ei.kingRing[Them])
567 ei.kingAttackersCount[Us]++;
568 ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
569 Bitboard bb = (b & ei.attackedBy[Them][KING]);
571 ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
574 mob = (Piece != QUEEN ? popcount<Max15>(b & mobilityArea)
575 : popcount<Full >(b & mobilityArea));
577 mobility += MobilityBonus[Piece][mob];
579 // Add a bonus if a slider is pinning an enemy piece
580 if ( (Piece == BISHOP || Piece == ROOK || Piece == QUEEN)
581 && (PseudoAttacks[Piece][pos.king_square(Them)] & s))
583 b = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
587 if (!more_than_one(b) && (b & pos.pieces(Them)))
588 score += ThreatBonus[Piece][type_of(pos.piece_on(lsb(b)))];
591 // Decrease score if we are attacked by an enemy pawn. Remaining part
592 // of threat evaluation must be done later when we have full attack info.
593 if (ei.attackedBy[Them][PAWN] & s)
594 score -= ThreatenedByPawnPenalty[Piece];
596 // Bishop and knight outposts squares
597 if ( (Piece == BISHOP || Piece == KNIGHT)
598 && !(pos.pieces(Them, PAWN) & attack_span_mask(Us, s)))
599 score += evaluate_outposts<Piece, Us>(pos, ei, s);
601 if ((Piece == ROOK || Piece == QUEEN) && relative_rank(Us, s) >= RANK_5)
603 // Major piece on 7th rank
604 if ( relative_rank(Us, s) == RANK_7
605 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
606 score += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
608 // Major piece attacking pawns on the same rank
609 Bitboard pawns = pos.pieces(Them, PAWN) & rank_bb(s);
611 score += (Piece == ROOK ? RookOnPawnBonus
612 : QueenOnPawnBonus) * popcount<Max15>(pawns);
615 // Special extra evaluation for bishops
616 if (Piece == BISHOP && pos.is_chess960())
618 // An important Chess960 pattern: A cornered bishop blocked by
619 // a friendly pawn diagonally in front of it is a very serious
620 // problem, especially when that pawn is also blocked.
621 if (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1))
623 Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
624 if (pos.piece_on(s + d) == make_piece(Us, PAWN))
626 if (!pos.is_empty(s + d + pawn_push(Us)))
627 score -= 2*TrappedBishopA1H1Penalty;
628 else if (pos.piece_on(s + 2*d) == make_piece(Us, PAWN))
629 score -= TrappedBishopA1H1Penalty;
631 score -= TrappedBishopA1H1Penalty / 2;
636 // Special extra evaluation for rooks
639 // Open and half-open files
641 if (ei.pi->file_is_half_open(Us, f))
643 if (ei.pi->file_is_half_open(Them, f))
644 score += RookOpenFileBonus;
646 score += RookHalfOpenFileBonus;
649 // Penalize rooks which are trapped inside a king. Penalize more if
650 // king has lost right to castle.
651 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
654 ksq = pos.king_square(Us);
656 if ( file_of(ksq) >= FILE_E
657 && file_of(s) > file_of(ksq)
658 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
660 // Is there a half-open file between the king and the edge of the board?
661 if (!ei.pi->has_open_file_to_right(Us, file_of(ksq)))
662 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
663 : (TrappedRookPenalty - mob * 16), 0);
665 else if ( file_of(ksq) <= FILE_D
666 && file_of(s) < file_of(ksq)
667 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
669 // Is there a half-open file between the king and the edge of the board?
670 if (!ei.pi->has_open_file_to_left(Us, file_of(ksq)))
671 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
672 : (TrappedRookPenalty - mob * 16), 0);
678 TracedScores[Us][Piece] = score;
684 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
685 // and the type of attacked one.
688 Score evaluate_threats(const Position& pos, EvalInfo& ei) {
690 const Color Them = (Us == WHITE ? BLACK : WHITE);
692 Bitboard b, undefendedMinors, weakEnemies;
693 Score score = SCORE_ZERO;
695 // Undefended minors get penalized even if not under attack
696 undefendedMinors = pos.pieces(Them)
697 & (pos.pieces(BISHOP) | pos.pieces(KNIGHT))
698 & ~ei.attackedBy[Them][0];
700 if (undefendedMinors)
701 score += more_than_one(undefendedMinors) ? UndefendedMinorPenalty * 2
702 : UndefendedMinorPenalty;
704 // Enemy pieces not defended by a pawn and under our attack
705 weakEnemies = pos.pieces(Them)
706 & ~ei.attackedBy[Them][PAWN]
707 & ei.attackedBy[Us][0];
712 // Add bonus according to type of attacked enemy piece and to the
713 // type of attacking piece, from knights to queens. Kings are not
714 // considered because are already handled in king evaluation.
715 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
717 b = ei.attackedBy[Us][pt1] & weakEnemies;
719 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
720 if (b & pos.pieces(pt2))
721 score += ThreatBonus[pt1][pt2];
727 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
728 // pieces of a given color.
730 template<Color Us, bool Trace>
731 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
733 const Color Them = (Us == WHITE ? BLACK : WHITE);
735 Score score = mobility = SCORE_ZERO;
737 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
738 const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces(Us));
740 score += evaluate_pieces<KNIGHT, Us, Trace>(pos, ei, mobility, mobilityArea);
741 score += evaluate_pieces<BISHOP, Us, Trace>(pos, ei, mobility, mobilityArea);
742 score += evaluate_pieces<ROOK, Us, Trace>(pos, ei, mobility, mobilityArea);
743 score += evaluate_pieces<QUEEN, Us, Trace>(pos, ei, mobility, mobilityArea);
745 // Sum up all attacked squares
746 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
747 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
748 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
753 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
755 template<Color Us, bool Trace>
756 Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) {
758 const Color Them = (Us == WHITE ? BLACK : WHITE);
760 Bitboard undefended, b, b1, b2, safe;
762 const Square ksq = pos.king_square(Us);
764 // King shelter and enemy pawns storm
765 Score score = ei.pi->king_safety<Us>(pos, ksq);
767 // King safety. This is quite complicated, and is almost certainly far
768 // from optimally tuned.
769 if ( ei.kingAttackersCount[Them] >= 2
770 && ei.kingAdjacentZoneAttacksCount[Them])
772 // Find the attacked squares around the king which has no defenders
773 // apart from the king itself
774 undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
775 undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
776 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
777 | ei.attackedBy[Us][QUEEN]);
779 // Initialize the 'attackUnits' variable, which is used later on as an
780 // index to the KingDangerTable[] array. The initial value is based on
781 // the number and types of the enemy's attacking pieces, the number of
782 // attacked and undefended squares around our king, the square of the
783 // king, and the quality of the pawn shelter.
784 attackUnits = std::min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
785 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
786 + InitKingDanger[relative_square(Us, ksq)]
787 - mg_value(score) / 32;
789 // Analyse enemy's safe queen contact checks. First find undefended
790 // squares around the king attacked by enemy queen...
791 b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
794 // ...then remove squares not supported by another enemy piece
795 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
796 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
798 attackUnits += QueenContactCheckBonus
800 * (Them == pos.side_to_move() ? 2 : 1);
803 // Analyse enemy's safe rook contact checks. First find undefended
804 // squares around the king attacked by enemy rooks...
805 b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
807 // Consider only squares where the enemy rook gives check
808 b &= PseudoAttacks[ROOK][ksq];
812 // ...then remove squares not supported by another enemy piece
813 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
814 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
816 attackUnits += RookContactCheckBonus
818 * (Them == pos.side_to_move() ? 2 : 1);
821 // Analyse enemy's safe distance checks for sliders and knights
822 safe = ~(pos.pieces(Them) | ei.attackedBy[Us][0]);
824 b1 = pos.attacks_from<ROOK>(ksq) & safe;
825 b2 = pos.attacks_from<BISHOP>(ksq) & safe;
827 // Enemy queen safe checks
828 b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
830 attackUnits += QueenCheckBonus * popcount<Max15>(b);
832 // Enemy rooks safe checks
833 b = b1 & ei.attackedBy[Them][ROOK];
835 attackUnits += RookCheckBonus * popcount<Max15>(b);
837 // Enemy bishops safe checks
838 b = b2 & ei.attackedBy[Them][BISHOP];
840 attackUnits += BishopCheckBonus * popcount<Max15>(b);
842 // Enemy knights safe checks
843 b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
845 attackUnits += KnightCheckBonus * popcount<Max15>(b);
847 // To index KingDangerTable[] attackUnits must be in [0, 99] range
848 attackUnits = std::min(99, std::max(0, attackUnits));
850 // Finally, extract the king danger score from the KingDangerTable[]
851 // array and subtract the score from evaluation. Set also margins[]
852 // value that will be used for pruning because this value can sometimes
853 // be very big, and so capturing a single attacking piece can therefore
854 // result in a score change far bigger than the value of the captured piece.
855 score -= KingDangerTable[Us == Search::RootColor][attackUnits];
856 margins[Us] += mg_value(KingDangerTable[Us == Search::RootColor][attackUnits]);
860 TracedScores[Us][KING] = score;
866 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
869 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
871 const Color Them = (Us == WHITE ? BLACK : WHITE);
873 Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
874 Score score = SCORE_ZERO;
876 b = ei.pi->passed_pawns(Us);
882 Square s = pop_lsb(&b);
884 assert(pos.pawn_is_passed(Us, s));
886 int r = int(relative_rank(Us, s) - RANK_2);
887 int rr = r * (r - 1);
889 // Base bonus based on rank
890 Value mbonus = Value(20 * rr);
891 Value ebonus = Value(10 * (rr + r + 1));
895 Square blockSq = s + pawn_push(Us);
897 // Adjust bonus based on kings proximity
898 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr);
899 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 2 * rr);
901 // If blockSq is not the queening square then consider also a second push
902 if (rank_of(blockSq) != (Us == WHITE ? RANK_8 : RANK_1))
903 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
905 // If the pawn is free to advance, increase bonus
906 if (pos.is_empty(blockSq))
908 squaresToQueen = forward_bb(Us, s);
909 defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
911 // If there is an enemy rook or queen attacking the pawn from behind,
912 // add all X-ray attacks by the rook or queen. Otherwise consider only
913 // the squares in the pawn's path attacked or occupied by the enemy.
914 if ( (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN))
915 && (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN) & pos.attacks_from<ROOK>(s)))
916 unsafeSquares = squaresToQueen;
918 unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces(Them));
920 // If there aren't enemy attacks or pieces along the path to queen give
921 // huge bonus. Even bigger if we protect the pawn's path.
923 ebonus += Value(rr * (squaresToQueen == defendedSquares ? 17 : 15));
925 // OK, there are enemy attacks or pieces (but not pawns). Are those
926 // squares which are attacked by the enemy also attacked by us ?
927 // If yes, big bonus (but smaller than when there are no enemy attacks),
928 // if no, somewhat smaller bonus.
929 ebonus += Value(rr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
933 // Increase the bonus if the passed pawn is supported by a friendly pawn
934 // on the same rank and a bit smaller if it's on the previous rank.
935 supportingPawns = pos.pieces(Us, PAWN) & adjacent_files_bb(file_of(s));
936 if (supportingPawns & rank_bb(s))
937 ebonus += Value(r * 20);
939 else if (supportingPawns & rank_bb(s - pawn_push(Us)))
940 ebonus += Value(r * 12);
942 // Rook pawns are a special case: They are sometimes worse, and
943 // sometimes better than other passed pawns. It is difficult to find
944 // good rules for determining whether they are good or bad. For now,
945 // we try the following: Increase the value for rook pawns if the
946 // other side has no pieces apart from a knight, and decrease the
947 // value if the other side has a rook or queen.
948 if (file_of(s) == FILE_A || file_of(s) == FILE_H)
950 if (pos.non_pawn_material(Them) <= KnightValueMg)
951 ebonus += ebonus / 4;
952 else if (pos.pieces(Them, ROOK, QUEEN))
953 ebonus -= ebonus / 4;
955 score += make_score(mbonus, ebonus);
959 // Add the scores to the middle game and endgame eval
960 return apply_weight(score, Weights[PassedPawns]);
964 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides, this is quite
965 // conservative and returns a winning score only when we are very sure that the pawn is winning.
967 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
969 Bitboard b, b2, blockers, supporters, queeningPath, candidates;
970 Square s, blockSq, queeningSquare;
971 Color c, winnerSide, loserSide;
972 bool pathDefended, opposed;
973 int pliesToGo, movesToGo, oppMovesToGo, sacptg, blockersCount, minKingDist, kingptg, d;
974 int pliesToQueen[] = { 256, 256 };
976 // Step 1. Hunt for unstoppable passed pawns. If we find at least one,
977 // record how many plies are required for promotion.
978 for (c = WHITE; c <= BLACK; c++)
980 // Skip if other side has non-pawn pieces
981 if (pos.non_pawn_material(~c))
984 b = ei.pi->passed_pawns(c);
989 queeningSquare = relative_square(c, file_of(s) | RANK_8);
990 queeningPath = forward_bb(c, s);
992 // Compute plies to queening and check direct advancement
993 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
994 oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
995 pathDefended = ((ei.attackedBy[c][0] & queeningPath) == queeningPath);
997 if (movesToGo >= oppMovesToGo && !pathDefended)
1000 // Opponent king cannot block because path is defended and position
1001 // is not in check. So only friendly pieces can be blockers.
1002 assert(!pos.checkers());
1003 assert((queeningPath & pos.pieces()) == (queeningPath & pos.pieces(c)));
1005 // Add moves needed to free the path from friendly pieces and retest condition
1006 movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
1008 if (movesToGo >= oppMovesToGo && !pathDefended)
1011 pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
1012 pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
1016 // Step 2. If either side cannot promote at least three plies before the other side then situation
1017 // becomes too complex and we give up. Otherwise we determine the possibly "winning side"
1018 if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3)
1021 winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
1022 loserSide = ~winnerSide;
1024 // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
1025 b = candidates = pos.pieces(loserSide, PAWN);
1031 // Compute plies from queening
1032 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
1033 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
1034 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
1036 // Check if (without even considering any obstacles) we're too far away or doubled
1037 if ( pliesToQueen[winnerSide] + 3 <= pliesToGo
1038 || (forward_bb(loserSide, s) & pos.pieces(loserSide, PAWN)))
1042 // If any candidate is already a passed pawn it _may_ promote in time. We give up.
1043 if (candidates & ei.pi->passed_pawns(loserSide))
1046 // Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
1052 sacptg = blockersCount = 0;
1053 minKingDist = kingptg = 256;
1055 // Compute plies from queening
1056 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
1057 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
1058 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
1060 // Generate list of blocking pawns and supporters
1061 supporters = adjacent_files_bb(file_of(s)) & candidates;
1062 opposed = forward_bb(loserSide, s) & pos.pieces(winnerSide, PAWN);
1063 blockers = passed_pawn_mask(loserSide, s) & pos.pieces(winnerSide, PAWN);
1067 // How many plies does it take to remove all the blocking pawns?
1070 blockSq = pop_lsb(&blockers);
1073 // Check pawns that can give support to overcome obstacle, for instance
1074 // black pawns: a4, b4 white: b2 then pawn in b4 is giving support.
1077 b2 = supporters & in_front_bb(winnerSide, blockSq + pawn_push(winnerSide));
1079 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1081 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1082 movesToGo = std::min(movesToGo, d);
1086 // Check pawns that can be sacrificed against the blocking pawn
1087 b2 = attack_span_mask(winnerSide, blockSq) & candidates & ~(1ULL << s);
1089 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1091 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1092 movesToGo = std::min(movesToGo, d);
1095 // If obstacle can be destroyed with an immediate pawn exchange / sacrifice,
1096 // it's not a real obstacle and we have nothing to add to pliesToGo.
1100 // Plies needed to sacrifice against all the blocking pawns
1101 sacptg += movesToGo * 2;
1104 // Plies needed for the king to capture all the blocking pawns
1105 d = square_distance(pos.king_square(loserSide), blockSq);
1106 minKingDist = std::min(minKingDist, d);
1107 kingptg = (minKingDist + blockersCount) * 2;
1110 // Check if pawn sacrifice plan _may_ save the day
1111 if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
1114 // Check if king capture plan _may_ save the day (contains some false positives)
1115 if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
1119 // Winning pawn is unstoppable and will promote as first, return big score
1120 Score score = make_score(0, (Value) 1280 - 32 * pliesToQueen[winnerSide]);
1121 return winnerSide == WHITE ? score : -score;
1125 // evaluate_space() computes the space evaluation for a given side. The
1126 // space evaluation is a simple bonus based on the number of safe squares
1127 // available for minor pieces on the central four files on ranks 2--4. Safe
1128 // squares one, two or three squares behind a friendly pawn are counted
1129 // twice. Finally, the space bonus is scaled by a weight taken from the
1130 // material hash table. The aim is to improve play on game opening.
1132 int evaluate_space(const Position& pos, EvalInfo& ei) {
1134 const Color Them = (Us == WHITE ? BLACK : WHITE);
1136 // Find the safe squares for our pieces inside the area defined by
1137 // SpaceMask[]. A square is unsafe if it is attacked by an enemy
1138 // pawn, or if it is undefended and attacked by an enemy piece.
1139 Bitboard safe = SpaceMask[Us]
1140 & ~pos.pieces(Us, PAWN)
1141 & ~ei.attackedBy[Them][PAWN]
1142 & (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
1144 // Find all squares which are at most three squares behind some friendly pawn
1145 Bitboard behind = pos.pieces(Us, PAWN);
1146 behind |= (Us == WHITE ? behind >> 8 : behind << 8);
1147 behind |= (Us == WHITE ? behind >> 16 : behind << 16);
1149 return popcount<Max15>(safe) + popcount<Max15>(behind & safe);
1153 // interpolate() interpolates between a middle game and an endgame score,
1154 // based on game phase. It also scales the return value by a ScaleFactor array.
1156 Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {
1158 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1159 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1160 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1162 int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
1163 int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
1164 return Value((result + GrainSize / 2) & ~(GrainSize - 1));
1168 // weight_option() computes the value of an evaluation weight, by combining
1169 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1171 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1173 // Scale option value from 100 to 256
1174 int mg = Options[mgOpt] * 256 / 100;
1175 int eg = Options[egOpt] * 256 / 100;
1177 return apply_weight(make_score(mg, eg), internalWeight);
1181 // A couple of little helpers used by tracing code, to_cp() converts a value to
1182 // a double in centipawns scale, trace_add() stores white and black scores.
1184 double to_cp(Value v) { return double(v) / double(PawnValueMg); }
1186 void trace_add(int idx, Score wScore, Score bScore) {
1188 TracedScores[WHITE][idx] = wScore;
1189 TracedScores[BLACK][idx] = bScore;
1193 // trace_row() is an helper function used by tracing code to register the
1194 // values of a single evaluation term.
1196 void trace_row(const char* name, int idx) {
1198 Score wScore = TracedScores[WHITE][idx];
1199 Score bScore = TracedScores[BLACK][idx];
1202 case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
1203 TraceStream << std::setw(20) << name << " | --- --- | --- --- | "
1204 << std::setw(6) << to_cp(mg_value(wScore)) << " "
1205 << std::setw(6) << to_cp(eg_value(wScore)) << " \n";
1208 TraceStream << std::setw(20) << name << " | " << std::noshowpos
1209 << std::setw(5) << to_cp(mg_value(wScore)) << " "
1210 << std::setw(5) << to_cp(eg_value(wScore)) << " | "
1211 << std::setw(5) << to_cp(mg_value(bScore)) << " "
1212 << std::setw(5) << to_cp(eg_value(bScore)) << " | "
1214 << std::setw(6) << to_cp(mg_value(wScore - bScore)) << " "
1215 << std::setw(6) << to_cp(eg_value(wScore - bScore)) << " \n";