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(-1, 29), 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 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
154 const Score RookOn7thBonus = make_score(47, 98);
155 const Score QueenOn7thBonus = make_score(27, 54);
157 // Rooks on open files (modified by Joona Kiiski)
158 const Score RookOpenFileBonus = make_score(43, 43);
159 const Score RookHalfOpenFileBonus = make_score(19, 19);
161 // Penalty for rooks trapped inside a friendly king which has lost the
163 const Value TrappedRookPenalty = Value(180);
165 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
166 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
167 // happen in Chess960 games.
168 const Score TrappedBishopA1H1Penalty = make_score(100, 100);
170 // The SpaceMask[Color] contains the area of the board which is considered
171 // by the space evaluation. In the middle game, each side is given a bonus
172 // based on how many squares inside this area are safe and available for
173 // friendly minor pieces.
174 const Bitboard SpaceMask[] = {
175 (1ULL << SQ_C2) | (1ULL << SQ_D2) | (1ULL << SQ_E2) | (1ULL << SQ_F2) |
176 (1ULL << SQ_C3) | (1ULL << SQ_D3) | (1ULL << SQ_E3) | (1ULL << SQ_F3) |
177 (1ULL << SQ_C4) | (1ULL << SQ_D4) | (1ULL << SQ_E4) | (1ULL << SQ_F4),
178 (1ULL << SQ_C7) | (1ULL << SQ_D7) | (1ULL << SQ_E7) | (1ULL << SQ_F7) |
179 (1ULL << SQ_C6) | (1ULL << SQ_D6) | (1ULL << SQ_E6) | (1ULL << SQ_F6) |
180 (1ULL << SQ_C5) | (1ULL << SQ_D5) | (1ULL << SQ_E5) | (1ULL << SQ_F5)
183 // King danger constants and variables. The king danger scores are taken
184 // from the KingDangerTable[]. Various little "meta-bonuses" measuring
185 // the strength of the enemy attack are added up into an integer, which
186 // is used as an index to KingDangerTable[].
188 // KingAttackWeights[PieceType] contains king attack weights by piece type
189 const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
191 // Bonuses for enemy's safe checks
192 const int QueenContactCheckBonus = 6;
193 const int RookContactCheckBonus = 4;
194 const int QueenCheckBonus = 3;
195 const int RookCheckBonus = 2;
196 const int BishopCheckBonus = 1;
197 const int KnightCheckBonus = 1;
199 // InitKingDanger[Square] contains penalties based on the position of the
200 // defending king, indexed by king's square (from white's point of view).
201 const int InitKingDanger[] = {
202 2, 0, 2, 5, 5, 2, 0, 2,
203 2, 2, 4, 8, 8, 4, 2, 2,
204 7, 10, 12, 12, 12, 12, 10, 7,
205 15, 15, 15, 15, 15, 15, 15, 15,
206 15, 15, 15, 15, 15, 15, 15, 15,
207 15, 15, 15, 15, 15, 15, 15, 15,
208 15, 15, 15, 15, 15, 15, 15, 15,
209 15, 15, 15, 15, 15, 15, 15, 15
212 // KingDangerTable[Color][attackUnits] contains the actual king danger
213 // weighted scores, indexed by color and by a calculated integer number.
214 Score KingDangerTable[2][128];
216 // TracedTerms[Color][PieceType || TracedType] contains a breakdown of the
217 // evaluation terms, used when tracing.
218 Score TracedScores[2][16];
219 std::stringstream TraceStream;
222 PST = 8, IMBALANCE = 9, MOBILITY = 10, THREAT = 11,
223 PASSED = 12, UNSTOPPABLE = 13, SPACE = 14, TOTAL = 15
226 // Function prototypes
228 Value do_evaluate(const Position& pos, Value& margin);
231 void init_eval_info(const Position& pos, EvalInfo& ei);
233 template<Color Us, bool Trace>
234 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility);
236 template<Color Us, bool Trace>
237 Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]);
240 Score evaluate_threats(const Position& pos, EvalInfo& ei);
243 int evaluate_space(const Position& pos, EvalInfo& ei);
246 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
248 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
250 inline Score apply_weight(Score v, Score weight);
251 Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf);
252 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
254 double to_cp(Value v);
255 void trace_add(int idx, Score term_w, Score term_b = SCORE_ZERO);
259 /// evaluate() is the main evaluation function. It always computes two
260 /// values, an endgame score and a middle game score, and interpolates
261 /// between them based on the remaining material.
262 Value evaluate(const Position& pos, Value& margin) { return do_evaluate<false>(pos, margin); }
267 Value do_evaluate(const Position& pos, Value& margin) {
271 Score score, mobilityWhite, mobilityBlack;
273 assert(pos.thread() >= 0 && pos.thread() < MAX_THREADS);
274 assert(!pos.in_check());
276 // Initialize score by reading the incrementally updated scores included
277 // in the position object (material + piece square tables).
280 // margins[] store the uncertainty estimation of position's evaluation
281 // that typically is used by the search for pruning decisions.
282 margins[WHITE] = margins[BLACK] = VALUE_ZERO;
284 // Probe the material hash table
285 ei.mi = Threads[pos.thread()].materialTable.material_info(pos);
286 score += ei.mi->material_value();
288 // If we have a specialized evaluation function for the current material
289 // configuration, call it and return.
290 if (ei.mi->specialized_eval_exists())
293 return ei.mi->evaluate(pos);
296 // Probe the pawn hash table
297 ei.pi = Threads[pos.thread()].pawnTable.pawn_info(pos);
298 score += ei.pi->pawns_value();
300 // Initialize attack and king safety bitboards
301 init_eval_info<WHITE>(pos, ei);
302 init_eval_info<BLACK>(pos, ei);
304 // Evaluate pieces and mobility
305 score += evaluate_pieces_of_color<WHITE, Trace>(pos, ei, mobilityWhite)
306 - evaluate_pieces_of_color<BLACK, Trace>(pos, ei, mobilityBlack);
308 score += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
310 // Evaluate kings after all other pieces because we need complete attack
311 // information when computing the king safety evaluation.
312 score += evaluate_king<WHITE, Trace>(pos, ei, margins)
313 - evaluate_king<BLACK, Trace>(pos, ei, margins);
315 // Evaluate tactical threats, we need full attack information including king
316 score += evaluate_threats<WHITE>(pos, ei)
317 - evaluate_threats<BLACK>(pos, ei);
319 // Evaluate passed pawns, we need full attack information including king
320 score += evaluate_passed_pawns<WHITE>(pos, ei)
321 - evaluate_passed_pawns<BLACK>(pos, ei);
323 // If one side has only a king, check whether exists any unstoppable passed pawn
324 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
325 score += evaluate_unstoppable_pawns(pos, ei);
327 // Evaluate space for both sides, only in middle-game.
328 if (ei.mi->space_weight())
330 int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
331 score += apply_weight(make_score(s * ei.mi->space_weight(), 0), Weights[Space]);
334 // Scale winning side if position is more drawish that what it appears
335 ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
336 : ei.mi->scale_factor(pos, BLACK);
338 // If we don't already have an unusual scale factor, check for opposite
339 // colored bishop endgames, and use a lower scale for those.
340 if ( ei.mi->game_phase() < PHASE_MIDGAME
341 && pos.opposite_colored_bishops()
342 && sf == SCALE_FACTOR_NORMAL)
344 // Only the two bishops ?
345 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
346 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
348 // Check for KBP vs KB with only a single pawn that is almost
349 // certainly a draw or at least two pawns.
350 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
351 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
354 // Endgame with opposite-colored bishops, but also other pieces. Still
355 // a bit drawish, but not as drawish as with only the two bishops.
356 sf = ScaleFactor(50);
359 // Interpolate between the middle game and the endgame score
360 margin = margins[pos.side_to_move()];
361 Value v = scale_by_game_phase(score, ei.mi->game_phase(), sf);
363 // In case of tracing add all single evaluation contributions for both white and black
366 trace_add(PST, pos.value());
367 trace_add(IMBALANCE, ei.mi->material_value());
368 trace_add(PAWN, ei.pi->pawns_value());
369 trace_add(MOBILITY, apply_weight(mobilityWhite, Weights[Mobility]), apply_weight(mobilityBlack, Weights[Mobility]));
370 trace_add(THREAT, evaluate_threats<WHITE>(pos, ei), evaluate_threats<BLACK>(pos, ei));
371 trace_add(PASSED, evaluate_passed_pawns<WHITE>(pos, ei), evaluate_passed_pawns<BLACK>(pos, ei));
372 trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei));
373 Score w = make_score(ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei), 0);
374 Score b = make_score(ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei), 0);
375 trace_add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
376 trace_add(TOTAL, score);
377 TraceStream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
378 << ", Black: " << to_cp(margins[BLACK])
379 << "\nScaling: " << std::noshowpos
380 << std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
381 << std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
382 << std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
383 << "Total evaluation: " << to_cp(v);
386 return pos.side_to_move() == WHITE ? v : -v;
392 /// read_weights() reads evaluation weights from the corresponding UCI parameters
394 void read_evaluation_uci_options(Color us) {
396 // King safety is asymmetrical. Our king danger level is weighted by
397 // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
398 const int kingDangerUs = (us == WHITE ? KingDangerUs : KingDangerThem);
399 const int kingDangerThem = (us == WHITE ? KingDangerThem : KingDangerUs);
401 Weights[Mobility] = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
402 Weights[PassedPawns] = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
403 Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
404 Weights[kingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
405 Weights[kingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
407 // If running in analysis mode, make sure we use symmetrical king safety. We do this
408 // by replacing both Weights[kingDangerUs] and Weights[kingDangerThem] by their average.
409 if (Options["UCI_AnalyseMode"])
410 Weights[kingDangerUs] = Weights[kingDangerThem] = (Weights[kingDangerUs] + Weights[kingDangerThem]) / 2;
418 // init_eval_info() initializes king bitboards for given color adding
419 // pawn attacks. To be done at the beginning of the evaluation.
422 void init_eval_info(const Position& pos, EvalInfo& ei) {
424 const Color Them = (Us == WHITE ? BLACK : WHITE);
426 Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
427 ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
429 // Init king safety tables only if we are going to use them
430 if ( pos.piece_count(Us, QUEEN)
431 && pos.non_pawn_material(Us) >= QueenValueMidgame + RookValueMidgame)
433 ei.kingRing[Them] = (b | (Us == WHITE ? b >> 8 : b << 8));
434 b &= ei.attackedBy[Us][PAWN];
435 ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
436 ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
438 ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
442 // evaluate_outposts() evaluates bishop and knight outposts squares
444 template<PieceType Piece, Color Us>
445 Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
447 const Color Them = (Us == WHITE ? BLACK : WHITE);
449 assert (Piece == BISHOP || Piece == KNIGHT);
451 // Initial bonus based on square
452 Value bonus = OutpostBonus[Piece == BISHOP][relative_square(Us, s)];
454 // Increase bonus if supported by pawn, especially if the opponent has
455 // no minor piece which can exchange the outpost piece.
456 if (bonus && (ei.attackedBy[Us][PAWN] & s))
458 if ( !pos.pieces(KNIGHT, Them)
459 && !(same_color_squares(s) & pos.pieces(BISHOP, Them)))
460 bonus += bonus + bonus / 2;
464 return make_score(bonus, bonus);
468 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
470 template<PieceType Piece, Color Us, bool Trace>
471 Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
477 Score score = SCORE_ZERO;
479 const Color Them = (Us == WHITE ? BLACK : WHITE);
480 const Square* pl = pos.piece_list(Us, Piece);
482 ei.attackedBy[Us][Piece] = 0;
484 while ((s = *pl++) != SQ_NONE)
486 // Find attacked squares, including x-ray attacks for bishops and rooks
487 if (Piece == KNIGHT || Piece == QUEEN)
488 b = pos.attacks_from<Piece>(s);
489 else if (Piece == BISHOP)
490 b = attacks_bb<BISHOP>(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
491 else if (Piece == ROOK)
492 b = attacks_bb<ROOK>(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
496 // Update attack info
497 ei.attackedBy[Us][Piece] |= b;
500 if (b & ei.kingRing[Them])
502 ei.kingAttackersCount[Us]++;
503 ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
504 Bitboard bb = (b & ei.attackedBy[Them][KING]);
506 ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
510 mob = (Piece != QUEEN ? popcount<Max15>(b & mobilityArea)
511 : popcount<Full >(b & mobilityArea));
513 mobility += MobilityBonus[Piece][mob];
515 // Decrease score if we are attacked by an enemy pawn. Remaining part
516 // of threat evaluation must be done later when we have full attack info.
517 if (ei.attackedBy[Them][PAWN] & s)
518 score -= ThreatenedByPawnPenalty[Piece];
520 // Bishop and knight outposts squares
521 if ( (Piece == BISHOP || Piece == KNIGHT)
522 && !(pos.pieces(PAWN, Them) & attack_span_mask(Us, s)))
523 score += evaluate_outposts<Piece, Us>(pos, ei, s);
525 // Queen or rook on 7th rank
526 if ( (Piece == ROOK || Piece == QUEEN)
527 && relative_rank(Us, s) == RANK_7
528 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
530 score += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
533 // Special extra evaluation for bishops
534 if (Piece == BISHOP && pos.is_chess960())
536 // An important Chess960 pattern: A cornered bishop blocked by
537 // a friendly pawn diagonally in front of it is a very serious
538 // problem, especially when that pawn is also blocked.
539 if (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1))
541 Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
542 if (pos.piece_on(s + d) == make_piece(Us, PAWN))
544 if (!pos.square_is_empty(s + d + pawn_push(Us)))
545 score -= 2*TrappedBishopA1H1Penalty;
546 else if (pos.piece_on(s + 2*d) == make_piece(Us, PAWN))
547 score -= TrappedBishopA1H1Penalty;
549 score -= TrappedBishopA1H1Penalty / 2;
554 // Special extra evaluation for rooks
557 // Open and half-open files
559 if (ei.pi->file_is_half_open(Us, f))
561 if (ei.pi->file_is_half_open(Them, f))
562 score += RookOpenFileBonus;
564 score += RookHalfOpenFileBonus;
567 // Penalize rooks which are trapped inside a king. Penalize more if
568 // king has lost right to castle.
569 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
572 ksq = pos.king_square(Us);
574 if ( file_of(ksq) >= FILE_E
575 && file_of(s) > file_of(ksq)
576 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
578 // Is there a half-open file between the king and the edge of the board?
579 if (!ei.pi->has_open_file_to_right(Us, file_of(ksq)))
580 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
581 : (TrappedRookPenalty - mob * 16), 0);
583 else if ( file_of(ksq) <= FILE_D
584 && file_of(s) < file_of(ksq)
585 && (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
587 // Is there a half-open file between the king and the edge of the board?
588 if (!ei.pi->has_open_file_to_left(Us, file_of(ksq)))
589 score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
590 : (TrappedRookPenalty - mob * 16), 0);
596 TracedScores[Us][Piece] = score;
602 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
603 // and the type of attacked one.
606 Score evaluate_threats(const Position& pos, EvalInfo& ei) {
608 const Color Them = (Us == WHITE ? BLACK : WHITE);
611 Score score = SCORE_ZERO;
613 // Enemy pieces not defended by a pawn and under our attack
614 Bitboard weakEnemies = pos.pieces(Them)
615 & ~ei.attackedBy[Them][PAWN]
616 & ei.attackedBy[Us][0];
620 // Add bonus according to type of attacked enemy piece and to the
621 // type of attacking piece, from knights to queens. Kings are not
622 // considered because are already handled in king evaluation.
623 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
625 b = ei.attackedBy[Us][pt1] & weakEnemies;
627 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
628 if (b & pos.pieces(pt2))
629 score += ThreatBonus[pt1][pt2];
635 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
636 // pieces of a given color.
638 template<Color Us, bool Trace>
639 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
641 const Color Them = (Us == WHITE ? BLACK : WHITE);
643 Score score = mobility = SCORE_ZERO;
645 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
646 const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces(Us));
648 score += evaluate_pieces<KNIGHT, Us, Trace>(pos, ei, mobility, mobilityArea);
649 score += evaluate_pieces<BISHOP, Us, Trace>(pos, ei, mobility, mobilityArea);
650 score += evaluate_pieces<ROOK, Us, Trace>(pos, ei, mobility, mobilityArea);
651 score += evaluate_pieces<QUEEN, Us, Trace>(pos, ei, mobility, mobilityArea);
653 // Sum up all attacked squares
654 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
655 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
656 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
661 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
663 template<Color Us, bool Trace>
664 Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) {
666 const Color Them = (Us == WHITE ? BLACK : WHITE);
668 Bitboard undefended, b, b1, b2, safe;
670 const Square ksq = pos.king_square(Us);
673 Score score = ei.pi->king_shelter<Us>(pos, ksq);
675 // King safety. This is quite complicated, and is almost certainly far
676 // from optimally tuned.
677 if ( ei.kingAttackersCount[Them] >= 2
678 && ei.kingAdjacentZoneAttacksCount[Them])
680 // Find the attacked squares around the king which has no defenders
681 // apart from the king itself
682 undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
683 undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
684 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
685 | ei.attackedBy[Us][QUEEN]);
687 // Initialize the 'attackUnits' variable, which is used later on as an
688 // index to the KingDangerTable[] array. The initial value is based on
689 // the number and types of the enemy's attacking pieces, the number of
690 // attacked and undefended squares around our king, the square of the
691 // king, and the quality of the pawn shelter.
692 attackUnits = std::min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
693 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
694 + InitKingDanger[relative_square(Us, ksq)]
695 - mg_value(ei.pi->king_shelter<Us>(pos, ksq)) / 32;
697 // Analyse enemy's safe queen contact checks. First find undefended
698 // squares around the king attacked by enemy queen...
699 b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
702 // ...then remove squares not supported by another enemy piece
703 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
704 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
706 attackUnits += QueenContactCheckBonus
708 * (Them == pos.side_to_move() ? 2 : 1);
711 // Analyse enemy's safe rook contact checks. First find undefended
712 // squares around the king attacked by enemy rooks...
713 b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
715 // Consider only squares where the enemy rook gives check
716 b &= PseudoAttacks[ROOK][ksq];
720 // ...then remove squares not supported by another enemy piece
721 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
722 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
724 attackUnits += RookContactCheckBonus
726 * (Them == pos.side_to_move() ? 2 : 1);
729 // Analyse enemy's safe distance checks for sliders and knights
730 safe = ~(pos.pieces(Them) | ei.attackedBy[Us][0]);
732 b1 = pos.attacks_from<ROOK>(ksq) & safe;
733 b2 = pos.attacks_from<BISHOP>(ksq) & safe;
735 // Enemy queen safe checks
736 b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
738 attackUnits += QueenCheckBonus * popcount<Max15>(b);
740 // Enemy rooks safe checks
741 b = b1 & ei.attackedBy[Them][ROOK];
743 attackUnits += RookCheckBonus * popcount<Max15>(b);
745 // Enemy bishops safe checks
746 b = b2 & ei.attackedBy[Them][BISHOP];
748 attackUnits += BishopCheckBonus * popcount<Max15>(b);
750 // Enemy knights safe checks
751 b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
753 attackUnits += KnightCheckBonus * popcount<Max15>(b);
755 // To index KingDangerTable[] attackUnits must be in [0, 99] range
756 attackUnits = std::min(99, std::max(0, attackUnits));
758 // Finally, extract the king danger score from the KingDangerTable[]
759 // array and subtract the score from evaluation. Set also margins[]
760 // value that will be used for pruning because this value can sometimes
761 // be very big, and so capturing a single attacking piece can therefore
762 // result in a score change far bigger than the value of the captured piece.
763 score -= KingDangerTable[Us][attackUnits];
764 margins[Us] += mg_value(KingDangerTable[Us][attackUnits]);
768 TracedScores[Us][KING] = score;
774 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
777 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
779 const Color Them = (Us == WHITE ? BLACK : WHITE);
781 Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
782 Score score = SCORE_ZERO;
784 b = ei.pi->passed_pawns(Us);
790 Square s = pop_1st_bit(&b);
792 assert(pos.pawn_is_passed(Us, s));
794 int r = int(relative_rank(Us, s) - RANK_2);
795 int rr = r * (r - 1);
797 // Base bonus based on rank
798 Value mbonus = Value(20 * rr);
799 Value ebonus = Value(10 * (rr + r + 1));
803 Square blockSq = s + pawn_push(Us);
805 // Adjust bonus based on kings proximity
806 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr);
807 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 2 * rr);
809 // If blockSq is not the queening square then consider also a second push
810 if (rank_of(blockSq) != (Us == WHITE ? RANK_8 : RANK_1))
811 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
813 // If the pawn is free to advance, increase bonus
814 if (pos.square_is_empty(blockSq))
816 squaresToQueen = squares_in_front_of(Us, s);
817 defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
819 // If there is an enemy rook or queen attacking the pawn from behind,
820 // add all X-ray attacks by the rook or queen. Otherwise consider only
821 // the squares in the pawn's path attacked or occupied by the enemy.
822 if ( (squares_in_front_of(Them, s) & pos.pieces(ROOK, QUEEN, Them))
823 && (squares_in_front_of(Them, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<ROOK>(s)))
824 unsafeSquares = squaresToQueen;
826 unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces(Them));
828 // If there aren't enemy attacks or pieces along the path to queen give
829 // huge bonus. Even bigger if we protect the pawn's path.
831 ebonus += Value(rr * (squaresToQueen == defendedSquares ? 17 : 15));
833 // OK, there are enemy attacks or pieces (but not pawns). Are those
834 // squares which are attacked by the enemy also attacked by us ?
835 // If yes, big bonus (but smaller than when there are no enemy attacks),
836 // if no, somewhat smaller bonus.
837 ebonus += Value(rr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
841 // Increase the bonus if the passed pawn is supported by a friendly pawn
842 // on the same rank and a bit smaller if it's on the previous rank.
843 supportingPawns = pos.pieces(PAWN, Us) & adjacent_files_bb(file_of(s));
844 if (supportingPawns & rank_bb(s))
845 ebonus += Value(r * 20);
847 else if (supportingPawns & rank_bb(s - pawn_push(Us)))
848 ebonus += Value(r * 12);
850 // Rook pawns are a special case: They are sometimes worse, and
851 // sometimes better than other passed pawns. It is difficult to find
852 // good rules for determining whether they are good or bad. For now,
853 // we try the following: Increase the value for rook pawns if the
854 // other side has no pieces apart from a knight, and decrease the
855 // value if the other side has a rook or queen.
856 if (file_of(s) == FILE_A || file_of(s) == FILE_H)
858 if (pos.non_pawn_material(Them) <= KnightValueMidgame)
859 ebonus += ebonus / 4;
860 else if (pos.pieces(ROOK, QUEEN, Them))
861 ebonus -= ebonus / 4;
863 score += make_score(mbonus, ebonus);
867 // Add the scores to the middle game and endgame eval
868 return apply_weight(score, Weights[PassedPawns]);
872 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides, this is quite
873 // conservative and returns a winning score only when we are very sure that the pawn is winning.
875 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
877 Bitboard b, b2, blockers, supporters, queeningPath, candidates;
878 Square s, blockSq, queeningSquare;
879 Color c, winnerSide, loserSide;
880 bool pathDefended, opposed;
881 int pliesToGo, movesToGo, oppMovesToGo, sacptg, blockersCount, minKingDist, kingptg, d;
882 int pliesToQueen[] = { 256, 256 };
884 // Step 1. Hunt for unstoppable passed pawns. If we find at least one,
885 // record how many plies are required for promotion.
886 for (c = WHITE; c <= BLACK; c++)
888 // Skip if other side has non-pawn pieces
889 if (pos.non_pawn_material(~c))
892 b = ei.pi->passed_pawns(c);
897 queeningSquare = relative_square(c, make_square(file_of(s), RANK_8));
898 queeningPath = squares_in_front_of(c, s);
900 // Compute plies to queening and check direct advancement
901 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
902 oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
903 pathDefended = ((ei.attackedBy[c][0] & queeningPath) == queeningPath);
905 if (movesToGo >= oppMovesToGo && !pathDefended)
908 // Opponent king cannot block because path is defended and position
909 // is not in check. So only friendly pieces can be blockers.
910 assert(!pos.in_check());
911 assert((queeningPath & pos.occupied_squares()) == (queeningPath & pos.pieces(c)));
913 // Add moves needed to free the path from friendly pieces and retest condition
914 movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
916 if (movesToGo >= oppMovesToGo && !pathDefended)
919 pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
920 pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
924 // Step 2. If either side cannot promote at least three plies before the other side then situation
925 // becomes too complex and we give up. Otherwise we determine the possibly "winning side"
926 if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3)
929 winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
930 loserSide = ~winnerSide;
932 // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
933 b = candidates = pos.pieces(PAWN, loserSide);
939 // Compute plies from queening
940 queeningSquare = relative_square(loserSide, make_square(file_of(s), RANK_8));
941 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
942 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
944 // Check if (without even considering any obstacles) we're too far away or doubled
945 if ( pliesToQueen[winnerSide] + 3 <= pliesToGo
946 || (squares_in_front_of(loserSide, s) & pos.pieces(PAWN, loserSide)))
950 // If any candidate is already a passed pawn it _may_ promote in time. We give up.
951 if (candidates & ei.pi->passed_pawns(loserSide))
954 // Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
960 sacptg = blockersCount = 0;
961 minKingDist = kingptg = 256;
963 // Compute plies from queening
964 queeningSquare = relative_square(loserSide, make_square(file_of(s), RANK_8));
965 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
966 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
968 // Generate list of blocking pawns and supporters
969 supporters = adjacent_files_bb(file_of(s)) & candidates;
970 opposed = squares_in_front_of(loserSide, s) & pos.pieces(PAWN, winnerSide);
971 blockers = passed_pawn_mask(loserSide, s) & pos.pieces(PAWN, winnerSide);
975 // How many plies does it take to remove all the blocking pawns?
978 blockSq = pop_1st_bit(&blockers);
981 // Check pawns that can give support to overcome obstacle, for instance
982 // black pawns: a4, b4 white: b2 then pawn in b4 is giving support.
985 b2 = supporters & in_front_bb(winnerSide, blockSq + pawn_push(winnerSide));
987 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
989 d = square_distance(blockSq, pop_1st_bit(&b2)) - 2;
990 movesToGo = std::min(movesToGo, d);
994 // Check pawns that can be sacrificed against the blocking pawn
995 b2 = attack_span_mask(winnerSide, blockSq) & candidates & ~(1ULL << s);
997 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
999 d = square_distance(blockSq, pop_1st_bit(&b2)) - 2;
1000 movesToGo = std::min(movesToGo, d);
1003 // If obstacle can be destroyed with an immediate pawn exchange / sacrifice,
1004 // it's not a real obstacle and we have nothing to add to pliesToGo.
1008 // Plies needed to sacrifice against all the blocking pawns
1009 sacptg += movesToGo * 2;
1012 // Plies needed for the king to capture all the blocking pawns
1013 d = square_distance(pos.king_square(loserSide), blockSq);
1014 minKingDist = std::min(minKingDist, d);
1015 kingptg = (minKingDist + blockersCount) * 2;
1018 // Check if pawn sacrifice plan _may_ save the day
1019 if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
1022 // Check if king capture plan _may_ save the day (contains some false positives)
1023 if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
1027 // Winning pawn is unstoppable and will promote as first, return big score
1028 Score score = make_score(0, (Value) 0x500 - 0x20 * pliesToQueen[winnerSide]);
1029 return winnerSide == WHITE ? score : -score;
1033 // evaluate_space() computes the space evaluation for a given side. The
1034 // space evaluation is a simple bonus based on the number of safe squares
1035 // available for minor pieces on the central four files on ranks 2--4. Safe
1036 // squares one, two or three squares behind a friendly pawn are counted
1037 // twice. Finally, the space bonus is scaled by a weight taken from the
1038 // material hash table. The aim is to improve play on game opening.
1040 int evaluate_space(const Position& pos, EvalInfo& ei) {
1042 const Color Them = (Us == WHITE ? BLACK : WHITE);
1044 // Find the safe squares for our pieces inside the area defined by
1045 // SpaceMask[]. A square is unsafe if it is attacked by an enemy
1046 // pawn, or if it is undefended and attacked by an enemy piece.
1047 Bitboard safe = SpaceMask[Us]
1048 & ~pos.pieces(PAWN, Us)
1049 & ~ei.attackedBy[Them][PAWN]
1050 & (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
1052 // Find all squares which are at most three squares behind some friendly pawn
1053 Bitboard behind = pos.pieces(PAWN, Us);
1054 behind |= (Us == WHITE ? behind >> 8 : behind << 8);
1055 behind |= (Us == WHITE ? behind >> 16 : behind << 16);
1057 return popcount<Max15>(safe) + popcount<Max15>(behind & safe);
1061 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1063 inline Score apply_weight(Score v, Score w) {
1064 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
1065 (int(eg_value(v)) * eg_value(w)) / 0x100);
1069 // scale_by_game_phase() interpolates between a middle game and an endgame score,
1070 // based on game phase. It also scales the return value by a ScaleFactor array.
1072 Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf) {
1074 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1075 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1076 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1078 int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
1079 int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
1080 return Value((result + GrainSize / 2) & ~(GrainSize - 1));
1084 // weight_option() computes the value of an evaluation weight, by combining
1085 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1087 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1089 // Scale option value from 100 to 256
1090 int mg = Options[mgOpt] * 256 / 100;
1091 int eg = Options[egOpt] * 256 / 100;
1093 return apply_weight(make_score(mg, eg), internalWeight);
1097 // init_safety() initizes the king safety evaluation, based on UCI
1098 // parameters. It is called from read_weights().
1100 void init_safety() {
1102 const Value MaxSlope = Value(30);
1103 const Value Peak = Value(1280);
1106 // First setup the base table
1107 for (int i = 0; i < 100; i++)
1109 t[i] = Value(int(0.4 * i * i));
1112 t[i] = std::min(t[i], t[i - 1] + MaxSlope);
1114 t[i] = std::min(t[i], Peak);
1117 // Then apply the weights and get the final KingDangerTable[] array
1118 for (Color c = WHITE; c <= BLACK; c++)
1119 for (int i = 0; i < 100; i++)
1120 KingDangerTable[c][i] = apply_weight(make_score(t[i], 0), Weights[KingDangerUs + c]);
1124 // A couple of little helpers used by tracing code, to_cp() converts a value to
1125 // a double in centipawns scale, trace_add() stores white and black scores.
1127 double to_cp(Value v) { return double(v) / double(PawnValueMidgame); }
1129 void trace_add(int idx, Score wScore, Score bScore) {
1131 TracedScores[WHITE][idx] = wScore;
1132 TracedScores[BLACK][idx] = bScore;
1135 // trace_row() is an helper function used by tracing code to register the
1136 // values of a single evaluation term.
1138 void trace_row(const char *name, int idx) {
1140 Score wScore = TracedScores[WHITE][idx];
1141 Score bScore = TracedScores[BLACK][idx];
1144 case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
1145 TraceStream << std::setw(20) << name << " | --- --- | --- --- | "
1146 << std::setw(6) << to_cp(mg_value(wScore)) << " "
1147 << std::setw(6) << to_cp(eg_value(wScore)) << " \n";
1150 TraceStream << std::setw(20) << name << " | " << std::noshowpos
1151 << std::setw(5) << to_cp(mg_value(wScore)) << " "
1152 << std::setw(5) << to_cp(eg_value(wScore)) << " | "
1153 << std::setw(5) << to_cp(mg_value(bScore)) << " "
1154 << std::setw(5) << to_cp(eg_value(bScore)) << " | "
1156 << std::setw(6) << to_cp(mg_value(wScore - bScore)) << " "
1157 << std::setw(6) << to_cp(eg_value(wScore - bScore)) << " \n";
1163 /// trace_evaluate() is like evaluate() but instead of a value returns a string
1164 /// suitable to be print on stdout with the detailed descriptions and values of
1165 /// each evaluation term. Used mainly for debugging.
1167 std::string trace_evaluate(const Position& pos) {
1172 TraceStream.str("");
1173 TraceStream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
1174 memset(TracedScores, 0, 2 * 16 * sizeof(Score));
1176 do_evaluate<true>(pos, margin);
1178 totals = TraceStream.str();
1179 TraceStream.str("");
1181 TraceStream << std::setw(21) << "Eval term " << "| White | Black | Total \n"
1182 << " | MG EG | MG EG | MG EG \n"
1183 << "---------------------+-------------+-------------+---------------\n";
1185 trace_row("Material, PST, Tempo", PST);
1186 trace_row("Material imbalance", IMBALANCE);
1187 trace_row("Pawns", PAWN);
1188 trace_row("Knights", KNIGHT);
1189 trace_row("Bishops", BISHOP);
1190 trace_row("Rooks", ROOK);
1191 trace_row("Queens", QUEEN);
1192 trace_row("Mobility", MOBILITY);
1193 trace_row("King safety", KING);
1194 trace_row("Threats", THREAT);
1195 trace_row("Passed pawns", PASSED);
1196 trace_row("Unstoppable pawns", UNSTOPPABLE);
1197 trace_row("Space", SPACE);
1199 TraceStream << "---------------------+-------------+-------------+---------------\n";
1200 trace_row("Total", TOTAL);
1201 TraceStream << totals;
1203 return TraceStream.str();