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[2][8];
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.
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[2];
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[2];
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[2];
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[][64] = {
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[][8] = {
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[2][128];
226 // TracedTerms[Color][PieceType || TracedType] contains a breakdown of the
227 // evaluation terms, used when tracing.
228 Score TracedScores[2][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);
271 Value ContemptFactor;
274 /// evaluate() is the main evaluation function. It always computes two
275 /// values, an endgame score and a middle game score, and interpolates
276 /// between them based on the remaining material.
278 Value evaluate(const Position& pos, Value& margin) {
279 return do_evaluate<false>(pos, margin);
283 /// init() computes evaluation weights from the corresponding UCI parameters
284 /// and setup king tables.
288 Weights[Mobility] = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
289 Weights[PassedPawns] = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
290 Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
291 Weights[KingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
292 Weights[KingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
294 // King safety is asymmetrical. Our king danger level is weighted by
295 // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
296 // If running in analysis mode, make sure we use symmetrical king safety. We
297 // do this by replacing both Weights[kingDangerUs] and Weights[kingDangerThem]
299 if (Options["UCI_AnalyseMode"])
300 Weights[KingDangerUs] = Weights[KingDangerThem] = (Weights[KingDangerUs] + Weights[KingDangerThem]) / 2;
302 const int MaxSlope = 30;
303 const int Peak = 1280;
305 for (int t = 0, i = 1; i < 100; i++)
307 t = std::min(Peak, std::min(int(0.4 * i * i), t + MaxSlope));
309 KingDangerTable[1][i] = apply_weight(make_score(t, 0), Weights[KingDangerUs]);
310 KingDangerTable[0][i] = apply_weight(make_score(t, 0), Weights[KingDangerThem]);
313 if (Options["UCI_AnalyseMode"])
314 ContemptFactor = VALUE_ZERO;
316 ContemptFactor = Options["Contempt Factor"] * PawnValueMg / 100;
320 /// trace() is like evaluate() but instead of a value returns a string suitable
321 /// to be print on stdout with the detailed descriptions and values of each
322 /// evaluation term. Used mainly for debugging.
324 std::string trace(const Position& pos) {
329 RootColor = pos.side_to_move();
332 TraceStream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
333 memset(TracedScores, 0, 2 * 16 * sizeof(Score));
335 do_evaluate<true>(pos, margin);
337 totals = TraceStream.str();
340 TraceStream << std::setw(21) << "Eval term " << "| White | Black | Total \n"
341 << " | MG EG | MG EG | MG EG \n"
342 << "---------------------+-------------+-------------+---------------\n";
344 trace_row("Material, PST, Tempo", PST);
345 trace_row("Material imbalance", IMBALANCE);
346 trace_row("Pawns", PAWN);
347 trace_row("Knights", KNIGHT);
348 trace_row("Bishops", BISHOP);
349 trace_row("Rooks", ROOK);
350 trace_row("Queens", QUEEN);
351 trace_row("Mobility", MOBILITY);
352 trace_row("King safety", KING);
353 trace_row("Threats", THREAT);
354 trace_row("Passed pawns", PASSED);
355 trace_row("Unstoppable pawns", UNSTOPPABLE);
356 trace_row("Space", SPACE);
358 TraceStream << "---------------------+-------------+-------------+---------------\n";
359 trace_row("Total", TOTAL);
360 TraceStream << totals;
362 return TraceStream.str();
371 Value do_evaluate(const Position& pos, Value& margin) {
373 assert(!pos.in_check());
377 Score score, mobilityWhite, mobilityBlack;
379 // margins[] store the uncertainty estimation of position's evaluation
380 // that typically is used by the search for pruning decisions.
381 margins[WHITE] = margins[BLACK] = VALUE_ZERO;
383 // Initialize score by reading the incrementally updated scores included
384 // in the position object (material + piece square tables) and adding
385 // Tempo bonus. Score is computed from the point of view of white.
386 score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
388 // Probe the material hash table
389 ei.mi = pos.this_thread()->materialTable.probe(pos);
390 score += ei.mi->material_value();
392 // If we have a specialized evaluation function for the current material
393 // configuration, call it and return.
394 if (ei.mi->specialized_eval_exists())
397 return ei.mi->evaluate(pos);
400 // Probe the pawn hash table
401 ei.pi = pos.this_thread()->pawnTable.probe(pos);
402 score += ei.pi->pawns_value();
404 // Initialize attack and king safety bitboards
405 init_eval_info<WHITE>(pos, ei);
406 init_eval_info<BLACK>(pos, ei);
408 // Evaluate pieces and mobility
409 score += evaluate_pieces_of_color<WHITE, Trace>(pos, ei, mobilityWhite)
410 - evaluate_pieces_of_color<BLACK, Trace>(pos, ei, mobilityBlack);
412 score += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
414 // Evaluate kings after all other pieces because we need complete attack
415 // information when computing the king safety evaluation.
416 score += evaluate_king<WHITE, Trace>(pos, ei, margins)
417 - evaluate_king<BLACK, Trace>(pos, ei, margins);
419 // Evaluate tactical threats, we need full attack information including king
420 score += evaluate_threats<WHITE>(pos, ei)
421 - evaluate_threats<BLACK>(pos, ei);
423 // Evaluate passed pawns, we need full attack information including king
424 score += evaluate_passed_pawns<WHITE>(pos, ei)
425 - evaluate_passed_pawns<BLACK>(pos, ei);
427 // If one side has only a king, check whether exists any unstoppable passed pawn
428 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
429 score += evaluate_unstoppable_pawns(pos, ei);
431 // Evaluate space for both sides, only in middle-game.
432 if (ei.mi->space_weight())
434 int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
435 score += apply_weight(make_score(s * ei.mi->space_weight(), 0), Weights[Space]);
438 // Scale winning side if position is more drawish that what it appears
439 ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
440 : ei.mi->scale_factor(pos, BLACK);
442 // If we don't already have an unusual scale factor, check for opposite
443 // colored bishop endgames, and use a lower scale for those.
444 if ( ei.mi->game_phase() < PHASE_MIDGAME
445 && pos.opposite_bishops()
446 && sf == SCALE_FACTOR_NORMAL)
448 // Only the two bishops ?
449 if ( pos.non_pawn_material(WHITE) == BishopValueMg
450 && pos.non_pawn_material(BLACK) == BishopValueMg)
452 // Check for KBP vs KB with only a single pawn that is almost
453 // certainly a draw or at least two pawns.
454 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
455 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
458 // Endgame with opposite-colored bishops, but also other pieces. Still
459 // a bit drawish, but not as drawish as with only the two bishops.
460 sf = ScaleFactor(50);
463 margin = margins[pos.side_to_move()];
464 Value v = interpolate(score, ei.mi->game_phase(), sf);
466 // In case of tracing add all single evaluation contributions for both white and black
469 trace_add(PST, pos.psq_score());
470 trace_add(IMBALANCE, ei.mi->material_value());
471 trace_add(PAWN, ei.pi->pawns_value());
472 trace_add(MOBILITY, apply_weight(mobilityWhite, Weights[Mobility]), apply_weight(mobilityBlack, Weights[Mobility]));
473 trace_add(THREAT, evaluate_threats<WHITE>(pos, ei), evaluate_threats<BLACK>(pos, ei));
474 trace_add(PASSED, evaluate_passed_pawns<WHITE>(pos, ei), evaluate_passed_pawns<BLACK>(pos, ei));
475 trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei));
476 Score w = make_score(ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei), 0);
477 Score b = make_score(ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei), 0);
478 trace_add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
479 trace_add(TOTAL, score);
480 TraceStream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
481 << ", Black: " << to_cp(margins[BLACK])
482 << "\nScaling: " << std::noshowpos
483 << std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
484 << std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
485 << std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
486 << "Total evaluation: " << to_cp(v);
489 return pos.side_to_move() == WHITE ? v : -v;
493 // init_eval_info() initializes king bitboards for given color adding
494 // pawn attacks. To be done at the beginning of the evaluation.
497 void init_eval_info(const Position& pos, EvalInfo& ei) {
499 const Color Them = (Us == WHITE ? BLACK : WHITE);
501 Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
502 ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
504 // Init king safety tables only if we are going to use them
505 if ( pos.piece_count(Us, QUEEN)
506 && pos.non_pawn_material(Us) >= QueenValueMg + RookValueMg)
508 ei.kingRing[Them] = (b | (Us == WHITE ? b >> 8 : b << 8));
509 b &= ei.attackedBy[Us][PAWN];
510 ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
511 ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
513 ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
517 // evaluate_outposts() evaluates bishop and knight outposts squares
519 template<PieceType Piece, Color Us>
520 Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
522 const Color Them = (Us == WHITE ? BLACK : WHITE);
524 assert (Piece == BISHOP || Piece == KNIGHT);
526 // Initial bonus based on square
527 Value bonus = OutpostBonus[Piece == BISHOP][relative_square(Us, s)];
529 // Increase bonus if supported by pawn, especially if the opponent has
530 // no minor piece which can exchange the outpost piece.
531 if (bonus && (ei.attackedBy[Us][PAWN] & s))
533 if ( !pos.pieces(Them, KNIGHT)
534 && !(same_color_squares(s) & pos.pieces(Them, BISHOP)))
535 bonus += bonus + bonus / 2;
539 return make_score(bonus, bonus);
543 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
545 template<PieceType Piece, Color Us, bool Trace>
546 Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
552 Score score = SCORE_ZERO;
554 const Color Them = (Us == WHITE ? BLACK : WHITE);
555 const Square* pl = pos.piece_list(Us, Piece);
557 ei.attackedBy[Us][Piece] = 0;
559 while ((s = *pl++) != SQ_NONE)
561 // Find attacked squares, including x-ray attacks for bishops and rooks
562 if (Piece == KNIGHT || Piece == QUEEN)
563 b = pos.attacks_from<Piece>(s);
564 else if (Piece == BISHOP)
565 b = attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN));
566 else if (Piece == ROOK)
567 b = attacks_bb<ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN));
571 ei.attackedBy[Us][Piece] |= b;
573 if (b & ei.kingRing[Them])
575 ei.kingAttackersCount[Us]++;
576 ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
577 Bitboard bb = (b & ei.attackedBy[Them][KING]);
579 ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
582 mob = (Piece != QUEEN ? popcount<Max15>(b & mobilityArea)
583 : popcount<Full >(b & mobilityArea));
585 mobility += MobilityBonus[Piece][mob];
587 // Add a bonus if a slider is pinning an enemy piece
588 if ( (Piece == BISHOP || Piece == ROOK || Piece == QUEEN)
589 && (PseudoAttacks[Piece][pos.king_square(Them)] & s))
591 b = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
595 if (!more_than_one(b) && (b & pos.pieces(Them)))
596 score += ThreatBonus[Piece][type_of(pos.piece_on(lsb(b)))];
599 // Decrease score if we are attacked by an enemy pawn. Remaining part
600 // of threat evaluation must be done later when we have full attack info.
601 if (ei.attackedBy[Them][PAWN] & s)
602 score -= ThreatenedByPawnPenalty[Piece];
604 // Bishop and knight outposts squares
605 if ( (Piece == BISHOP || Piece == KNIGHT)
606 && !(pos.pieces(Them, PAWN) & attack_span_mask(Us, s)))
607 score += evaluate_outposts<Piece, Us>(pos, ei, s);
609 if ((Piece == ROOK || Piece == QUEEN) && relative_rank(Us, s) >= RANK_5)
611 // Major piece on 7th rank
612 if ( relative_rank(Us, s) == RANK_7
613 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
614 score += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
616 // Major piece attacking pawns on the same rank
617 Bitboard pawns = pos.pieces(Them, PAWN) & rank_bb(s);
619 score += (Piece == ROOK ? RookOnPawnBonus
620 : QueenOnPawnBonus) * popcount<Max15>(pawns);
623 // Special extra evaluation for bishops
624 if (Piece == BISHOP && pos.is_chess960())
626 // An important Chess960 pattern: A cornered bishop blocked by
627 // a friendly pawn diagonally in front of it is a very serious
628 // problem, especially when that pawn is also blocked.
629 if (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1))
631 Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
632 if (pos.piece_on(s + d) == make_piece(Us, PAWN))
634 if (!pos.is_empty(s + d + pawn_push(Us)))
635 score -= 2*TrappedBishopA1H1Penalty;
636 else if (pos.piece_on(s + 2*d) == make_piece(Us, PAWN))
637 score -= TrappedBishopA1H1Penalty;
639 score -= TrappedBishopA1H1Penalty / 2;
644 // Special extra evaluation for rooks
647 // Open and half-open files
649 if (ei.pi->file_is_half_open(Us, f))
651 if (ei.pi->file_is_half_open(Them, f))
652 score += RookOpenFileBonus;
654 score += RookHalfOpenFileBonus;
657 // Penalize rooks which are trapped inside a king. Penalize more if
658 // king has lost right to castle.
659 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
662 ksq = pos.king_square(Us);
664 if ( file_of(ksq) >= FILE_E
665 && file_of(s) > file_of(ksq)
666 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
668 // Is there a half-open file between the king and the edge of the board?
669 if (!ei.pi->has_open_file_to_right(Us, file_of(ksq)))
670 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
671 : (TrappedRookPenalty - mob * 16), 0);
673 else if ( file_of(ksq) <= FILE_D
674 && file_of(s) < file_of(ksq)
675 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
677 // Is there a half-open file between the king and the edge of the board?
678 if (!ei.pi->has_open_file_to_left(Us, file_of(ksq)))
679 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
680 : (TrappedRookPenalty - mob * 16), 0);
686 TracedScores[Us][Piece] = score;
692 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
693 // and the type of attacked one.
696 Score evaluate_threats(const Position& pos, EvalInfo& ei) {
698 const Color Them = (Us == WHITE ? BLACK : WHITE);
700 Bitboard b, undefendedMinors, weakEnemies;
701 Score score = SCORE_ZERO;
703 // Undefended minors get penalized even if not under attack
704 undefendedMinors = pos.pieces(Them)
705 & (pos.pieces(BISHOP) | pos.pieces(KNIGHT))
706 & ~ei.attackedBy[Them][0];
708 if (undefendedMinors)
709 score += more_than_one(undefendedMinors) ? UndefendedMinorPenalty * 2
710 : UndefendedMinorPenalty;
712 // Enemy pieces not defended by a pawn and under our attack
713 weakEnemies = pos.pieces(Them)
714 & ~ei.attackedBy[Them][PAWN]
715 & ei.attackedBy[Us][0];
720 // Add bonus according to type of attacked enemy piece and to the
721 // type of attacking piece, from knights to queens. Kings are not
722 // considered because are already handled in king evaluation.
723 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
725 b = ei.attackedBy[Us][pt1] & weakEnemies;
727 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
728 if (b & pos.pieces(pt2))
729 score += ThreatBonus[pt1][pt2];
735 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
736 // pieces of a given color.
738 template<Color Us, bool Trace>
739 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
741 const Color Them = (Us == WHITE ? BLACK : WHITE);
743 Score score = mobility = SCORE_ZERO;
745 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
746 const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces(Us));
748 score += evaluate_pieces<KNIGHT, Us, Trace>(pos, ei, mobility, mobilityArea);
749 score += evaluate_pieces<BISHOP, Us, Trace>(pos, ei, mobility, mobilityArea);
750 score += evaluate_pieces<ROOK, Us, Trace>(pos, ei, mobility, mobilityArea);
751 score += evaluate_pieces<QUEEN, Us, Trace>(pos, ei, mobility, mobilityArea);
753 // Sum up all attacked squares
754 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
755 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
756 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
761 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
763 template<Color Us, bool Trace>
764 Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) {
766 const Color Them = (Us == WHITE ? BLACK : WHITE);
768 Bitboard undefended, b, b1, b2, safe;
770 const Square ksq = pos.king_square(Us);
772 // King shelter and enemy pawns storm
773 Score score = ei.pi->king_safety<Us>(pos, ksq);
775 // King safety. This is quite complicated, and is almost certainly far
776 // from optimally tuned.
777 if ( ei.kingAttackersCount[Them] >= 2
778 && ei.kingAdjacentZoneAttacksCount[Them])
780 // Find the attacked squares around the king which has no defenders
781 // apart from the king itself
782 undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
783 undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
784 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
785 | ei.attackedBy[Us][QUEEN]);
787 // Initialize the 'attackUnits' variable, which is used later on as an
788 // index to the KingDangerTable[] array. The initial value is based on
789 // the number and types of the enemy's attacking pieces, the number of
790 // attacked and undefended squares around our king, the square of the
791 // king, and the quality of the pawn shelter.
792 attackUnits = std::min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
793 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
794 + InitKingDanger[relative_square(Us, ksq)]
795 - mg_value(score) / 32;
797 // Analyse enemy's safe queen contact checks. First find undefended
798 // squares around the king attacked by enemy queen...
799 b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
802 // ...then remove squares not supported by another enemy piece
803 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
804 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
806 attackUnits += QueenContactCheckBonus
808 * (Them == pos.side_to_move() ? 2 : 1);
811 // Analyse enemy's safe rook contact checks. First find undefended
812 // squares around the king attacked by enemy rooks...
813 b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
815 // Consider only squares where the enemy rook gives check
816 b &= PseudoAttacks[ROOK][ksq];
820 // ...then remove squares not supported by another enemy piece
821 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
822 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
824 attackUnits += RookContactCheckBonus
826 * (Them == pos.side_to_move() ? 2 : 1);
829 // Analyse enemy's safe distance checks for sliders and knights
830 safe = ~(pos.pieces(Them) | ei.attackedBy[Us][0]);
832 b1 = pos.attacks_from<ROOK>(ksq) & safe;
833 b2 = pos.attacks_from<BISHOP>(ksq) & safe;
835 // Enemy queen safe checks
836 b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
838 attackUnits += QueenCheckBonus * popcount<Max15>(b);
840 // Enemy rooks safe checks
841 b = b1 & ei.attackedBy[Them][ROOK];
843 attackUnits += RookCheckBonus * popcount<Max15>(b);
845 // Enemy bishops safe checks
846 b = b2 & ei.attackedBy[Them][BISHOP];
848 attackUnits += BishopCheckBonus * popcount<Max15>(b);
850 // Enemy knights safe checks
851 b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
853 attackUnits += KnightCheckBonus * popcount<Max15>(b);
855 // To index KingDangerTable[] attackUnits must be in [0, 99] range
856 attackUnits = std::min(99, std::max(0, attackUnits));
858 // Finally, extract the king danger score from the KingDangerTable[]
859 // array and subtract the score from evaluation. Set also margins[]
860 // value that will be used for pruning because this value can sometimes
861 // be very big, and so capturing a single attacking piece can therefore
862 // result in a score change far bigger than the value of the captured piece.
863 score -= KingDangerTable[Us == Eval::RootColor][attackUnits];
864 margins[Us] += mg_value(KingDangerTable[Us == Eval::RootColor][attackUnits]);
868 TracedScores[Us][KING] = score;
874 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
877 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
879 const Color Them = (Us == WHITE ? BLACK : WHITE);
881 Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
882 Score score = SCORE_ZERO;
884 b = ei.pi->passed_pawns(Us);
890 Square s = pop_lsb(&b);
892 assert(pos.pawn_is_passed(Us, s));
894 int r = int(relative_rank(Us, s) - RANK_2);
895 int rr = r * (r - 1);
897 // Base bonus based on rank
898 Value mbonus = Value(20 * rr);
899 Value ebonus = Value(10 * (rr + r + 1));
903 Square blockSq = s + pawn_push(Us);
905 // Adjust bonus based on kings proximity
906 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr);
907 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 2 * rr);
909 // If blockSq is not the queening square then consider also a second push
910 if (rank_of(blockSq) != (Us == WHITE ? RANK_8 : RANK_1))
911 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
913 // If the pawn is free to advance, increase bonus
914 if (pos.is_empty(blockSq))
916 squaresToQueen = forward_bb(Us, s);
917 defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
919 // If there is an enemy rook or queen attacking the pawn from behind,
920 // add all X-ray attacks by the rook or queen. Otherwise consider only
921 // the squares in the pawn's path attacked or occupied by the enemy.
922 if ( (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN))
923 && (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN) & pos.attacks_from<ROOK>(s)))
924 unsafeSquares = squaresToQueen;
926 unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces(Them));
928 // If there aren't enemy attacks or pieces along the path to queen give
929 // huge bonus. Even bigger if we protect the pawn's path.
931 ebonus += Value(rr * (squaresToQueen == defendedSquares ? 17 : 15));
933 // OK, there are enemy attacks or pieces (but not pawns). Are those
934 // squares which are attacked by the enemy also attacked by us ?
935 // If yes, big bonus (but smaller than when there are no enemy attacks),
936 // if no, somewhat smaller bonus.
937 ebonus += Value(rr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
941 // Increase the bonus if the passed pawn is supported by a friendly pawn
942 // on the same rank and a bit smaller if it's on the previous rank.
943 supportingPawns = pos.pieces(Us, PAWN) & adjacent_files_bb(file_of(s));
944 if (supportingPawns & rank_bb(s))
945 ebonus += Value(r * 20);
947 else if (supportingPawns & rank_bb(s - pawn_push(Us)))
948 ebonus += Value(r * 12);
950 // Rook pawns are a special case: They are sometimes worse, and
951 // sometimes better than other passed pawns. It is difficult to find
952 // good rules for determining whether they are good or bad. For now,
953 // we try the following: Increase the value for rook pawns if the
954 // other side has no pieces apart from a knight, and decrease the
955 // value if the other side has a rook or queen.
956 if (file_of(s) == FILE_A || file_of(s) == FILE_H)
958 if (pos.non_pawn_material(Them) <= KnightValueMg)
959 ebonus += ebonus / 4;
960 else if (pos.pieces(Them, ROOK, QUEEN))
961 ebonus -= ebonus / 4;
963 score += make_score(mbonus, ebonus);
967 // Add the scores to the middle game and endgame eval
968 return apply_weight(score, Weights[PassedPawns]);
972 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides, this is quite
973 // conservative and returns a winning score only when we are very sure that the pawn is winning.
975 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
977 Bitboard b, b2, blockers, supporters, queeningPath, candidates;
978 Square s, blockSq, queeningSquare;
979 Color c, winnerSide, loserSide;
980 bool pathDefended, opposed;
981 int pliesToGo, movesToGo, oppMovesToGo, sacptg, blockersCount, minKingDist, kingptg, d;
982 int pliesToQueen[] = { 256, 256 };
984 // Step 1. Hunt for unstoppable passed pawns. If we find at least one,
985 // record how many plies are required for promotion.
986 for (c = WHITE; c <= BLACK; c++)
988 // Skip if other side has non-pawn pieces
989 if (pos.non_pawn_material(~c))
992 b = ei.pi->passed_pawns(c);
997 queeningSquare = relative_square(c, file_of(s) | RANK_8);
998 queeningPath = forward_bb(c, s);
1000 // Compute plies to queening and check direct advancement
1001 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
1002 oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
1003 pathDefended = ((ei.attackedBy[c][0] & queeningPath) == queeningPath);
1005 if (movesToGo >= oppMovesToGo && !pathDefended)
1008 // Opponent king cannot block because path is defended and position
1009 // is not in check. So only friendly pieces can be blockers.
1010 assert(!pos.in_check());
1011 assert((queeningPath & pos.pieces()) == (queeningPath & pos.pieces(c)));
1013 // Add moves needed to free the path from friendly pieces and retest condition
1014 movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
1016 if (movesToGo >= oppMovesToGo && !pathDefended)
1019 pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
1020 pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
1024 // Step 2. If either side cannot promote at least three plies before the other side then situation
1025 // becomes too complex and we give up. Otherwise we determine the possibly "winning side"
1026 if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3)
1029 winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
1030 loserSide = ~winnerSide;
1032 // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
1033 b = candidates = pos.pieces(loserSide, PAWN);
1039 // Compute plies from queening
1040 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
1041 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
1042 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
1044 // Check if (without even considering any obstacles) we're too far away or doubled
1045 if ( pliesToQueen[winnerSide] + 3 <= pliesToGo
1046 || (forward_bb(loserSide, s) & pos.pieces(loserSide, PAWN)))
1050 // If any candidate is already a passed pawn it _may_ promote in time. We give up.
1051 if (candidates & ei.pi->passed_pawns(loserSide))
1054 // Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
1060 sacptg = blockersCount = 0;
1061 minKingDist = kingptg = 256;
1063 // Compute plies from queening
1064 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
1065 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
1066 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
1068 // Generate list of blocking pawns and supporters
1069 supporters = adjacent_files_bb(file_of(s)) & candidates;
1070 opposed = forward_bb(loserSide, s) & pos.pieces(winnerSide, PAWN);
1071 blockers = passed_pawn_mask(loserSide, s) & pos.pieces(winnerSide, PAWN);
1075 // How many plies does it take to remove all the blocking pawns?
1078 blockSq = pop_lsb(&blockers);
1081 // Check pawns that can give support to overcome obstacle, for instance
1082 // black pawns: a4, b4 white: b2 then pawn in b4 is giving support.
1085 b2 = supporters & in_front_bb(winnerSide, blockSq + pawn_push(winnerSide));
1087 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1089 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1090 movesToGo = std::min(movesToGo, d);
1094 // Check pawns that can be sacrificed against the blocking pawn
1095 b2 = attack_span_mask(winnerSide, blockSq) & candidates & ~(1ULL << s);
1097 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1099 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1100 movesToGo = std::min(movesToGo, d);
1103 // If obstacle can be destroyed with an immediate pawn exchange / sacrifice,
1104 // it's not a real obstacle and we have nothing to add to pliesToGo.
1108 // Plies needed to sacrifice against all the blocking pawns
1109 sacptg += movesToGo * 2;
1112 // Plies needed for the king to capture all the blocking pawns
1113 d = square_distance(pos.king_square(loserSide), blockSq);
1114 minKingDist = std::min(minKingDist, d);
1115 kingptg = (minKingDist + blockersCount) * 2;
1118 // Check if pawn sacrifice plan _may_ save the day
1119 if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
1122 // Check if king capture plan _may_ save the day (contains some false positives)
1123 if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
1127 // Winning pawn is unstoppable and will promote as first, return big score
1128 Score score = make_score(0, (Value) 1280 - 32 * pliesToQueen[winnerSide]);
1129 return winnerSide == WHITE ? score : -score;
1133 // evaluate_space() computes the space evaluation for a given side. The
1134 // space evaluation is a simple bonus based on the number of safe squares
1135 // available for minor pieces on the central four files on ranks 2--4. Safe
1136 // squares one, two or three squares behind a friendly pawn are counted
1137 // twice. Finally, the space bonus is scaled by a weight taken from the
1138 // material hash table. The aim is to improve play on game opening.
1140 int evaluate_space(const Position& pos, EvalInfo& ei) {
1142 const Color Them = (Us == WHITE ? BLACK : WHITE);
1144 // Find the safe squares for our pieces inside the area defined by
1145 // SpaceMask[]. A square is unsafe if it is attacked by an enemy
1146 // pawn, or if it is undefended and attacked by an enemy piece.
1147 Bitboard safe = SpaceMask[Us]
1148 & ~pos.pieces(Us, PAWN)
1149 & ~ei.attackedBy[Them][PAWN]
1150 & (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
1152 // Find all squares which are at most three squares behind some friendly pawn
1153 Bitboard behind = pos.pieces(Us, PAWN);
1154 behind |= (Us == WHITE ? behind >> 8 : behind << 8);
1155 behind |= (Us == WHITE ? behind >> 16 : behind << 16);
1157 return popcount<Max15>(safe) + popcount<Max15>(behind & safe);
1161 // interpolate() interpolates between a middle game and an endgame score,
1162 // based on game phase. It also scales the return value by a ScaleFactor array.
1164 Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {
1166 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1167 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1168 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1170 int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
1171 int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
1172 return Value((result + GrainSize / 2) & ~(GrainSize - 1));
1176 // weight_option() computes the value of an evaluation weight, by combining
1177 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1179 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1181 // Scale option value from 100 to 256
1182 int mg = Options[mgOpt] * 256 / 100;
1183 int eg = Options[egOpt] * 256 / 100;
1185 return apply_weight(make_score(mg, eg), internalWeight);
1189 // A couple of little helpers used by tracing code, to_cp() converts a value to
1190 // a double in centipawns scale, trace_add() stores white and black scores.
1192 double to_cp(Value v) { return double(v) / double(PawnValueMg); }
1194 void trace_add(int idx, Score wScore, Score bScore) {
1196 TracedScores[WHITE][idx] = wScore;
1197 TracedScores[BLACK][idx] = bScore;
1201 // trace_row() is an helper function used by tracing code to register the
1202 // values of a single evaluation term.
1204 void trace_row(const char* name, int idx) {
1206 Score wScore = TracedScores[WHITE][idx];
1207 Score bScore = TracedScores[BLACK][idx];
1210 case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
1211 TraceStream << std::setw(20) << name << " | --- --- | --- --- | "
1212 << std::setw(6) << to_cp(mg_value(wScore)) << " "
1213 << std::setw(6) << to_cp(eg_value(wScore)) << " \n";
1216 TraceStream << std::setw(20) << name << " | " << std::noshowpos
1217 << std::setw(5) << to_cp(mg_value(wScore)) << " "
1218 << std::setw(5) << to_cp(eg_value(wScore)) << " | "
1219 << std::setw(5) << to_cp(mg_value(bScore)) << " "
1220 << std::setw(5) << to_cp(eg_value(bScore)) << " | "
1222 << std::setw(6) << to_cp(mg_value(wScore - bScore)) << " "
1223 << std::setw(6) << to_cp(eg_value(wScore - bScore)) << " \n";