2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 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/>.
35 #include "ucioption.h"
39 //// Local definitions
44 // Struct EvalInfo contains various information computed and collected
45 // by the evaluation functions.
48 // Pointer to pawn hash table entry
51 // attackedBy[color][piece type] is a bitboard representing all squares
52 // attacked by a given color and piece type, attackedBy[color][0] contains
53 // all squares attacked by the given color.
54 Bitboard attackedBy[2][8];
56 // kingZone[color] is the zone around the enemy king which is considered
57 // by the king safety evaluation. This consists of the squares directly
58 // adjacent to the king, and the three (or two, for a king on an edge file)
59 // squares two ranks in front of the king. For instance, if black's king
60 // is on g8, kingZone[WHITE] is a bitboard containing the squares f8, h8,
61 // f7, g7, h7, f6, g6 and h6.
64 // kingAttackersCount[color] is the number of pieces of the given color
65 // which attack a square in the kingZone of the enemy king.
66 int kingAttackersCount[2];
68 // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
69 // given color which attack a square in the kingZone of the enemy king. The
70 // weights of the individual piece types are given by the variables
71 // QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
72 // KnightAttackWeight in evaluate.cpp
73 int kingAttackersWeight[2];
75 // kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
76 // directly adjacent to the king of the given color. Pieces which attack
77 // more than one square are counted multiple times. For instance, if black's
78 // king is on g8 and there's a white knight on g5, this knight adds
79 // 2 to kingAdjacentZoneAttacksCount[BLACK].
80 int kingAdjacentZoneAttacksCount[2];
83 // Evaluation grain size, must be a power of 2
84 const int GrainSize = 8;
86 // Evaluation weights, initialized from UCI options
87 enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
91 #define S(mg, eg) make_score(mg, eg)
93 // Internal evaluation weights. These are applied on top of the evaluation
94 // weights read from UCI parameters. The purpose is to be able to change
95 // the evaluation weights while keeping the default values of the UCI
96 // parameters at 100, which looks prettier.
98 // Values modified by Joona Kiiski
99 const Score WeightsInternal[] = {
100 S(248, 271), S(233, 201), S(252, 259), S(46, 0), S(247, 0), S(259, 0)
103 // MobilityBonus[PieceType][attacked] contains mobility bonuses for middle and
104 // end game, indexed by piece type and number of attacked squares not occupied
105 // by friendly pieces.
106 const Score MobilityBonus[][32] = {
108 { S(-38,-33), S(-25,-23), S(-12,-13), S( 0, -3), S(12, 7), S(25, 17), // Knights
109 S( 31, 22), S( 38, 27), S( 38, 27) },
110 { S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12), S(31, 26), S(45, 40), // Bishops
111 S( 57, 52), S( 65, 60), S( 71, 65), S(74, 69), S(76, 71), S(78, 73),
112 S( 79, 74), S( 80, 75), S( 81, 76), S(81, 76) },
113 { S(-20,-36), S(-14,-19), S( -8, -3), S(-2, 13), S( 4, 29), S(10, 46), // Rooks
114 S( 14, 62), S( 19, 79), S( 23, 95), S(26,106), S(27,111), S(28,114),
115 S( 29,116), S( 30,117), S( 31,118), S(32,118) },
116 { S(-10,-18), S( -8,-13), S( -6, -7), S(-3, -2), S(-1, 3), S( 1, 8), // Queens
117 S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
118 S( 16, 35), S( 17, 35), S( 18, 35), S(20, 35), S(20, 35), S(20, 35),
119 S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
120 S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
121 S( 20, 35), S( 20, 35) }
124 // OutpostBonus[PieceType][Square] contains outpost bonuses of knights and
125 // bishops, indexed by piece type and square (from white's point of view).
126 const Value OutpostBonus[][64] = {
129 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
130 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
131 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
132 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
133 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
134 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },
136 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
137 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
138 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
139 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
140 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
141 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }
144 // ThreatBonus[attacking][attacked] contains threat bonuses according to
145 // which piece type attacks which one.
146 const Score ThreatBonus[][8] = {
148 { S(0, 0), S( 7, 39), S( 0, 0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT
149 { S(0, 0), S( 7, 39), S(24, 49), S( 0, 0), S(41,100), S(41,100) }, // BISHOP
150 { S(0, 0), S(-1, 29), S(15, 49), S(15, 49), S( 0, 0), S(24, 49) }, // ROOK
151 { S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0, 0) } // QUEEN
154 // ThreatedByPawnPenalty[PieceType] contains a penalty according to which
155 // piece type is attacked by an enemy pawn.
156 const Score ThreatedByPawnPenalty[] = {
157 S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
162 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
163 const Score RookOn7thBonus = make_score(47, 98);
164 const Score QueenOn7thBonus = make_score(27, 54);
166 // Rooks on open files (modified by Joona Kiiski)
167 const Score RookOpenFileBonus = make_score(43, 43);
168 const Score RookHalfOpenFileBonus = make_score(19, 19);
170 // Penalty for rooks trapped inside a friendly king which has lost the
172 const Value TrappedRookPenalty = Value(180);
174 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
175 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
176 // happen in Chess960 games.
177 const Score TrappedBishopA1H1Penalty = make_score(100, 100);
179 // The SpaceMask[Color] contains the area of the board which is considered
180 // by the space evaluation. In the middle game, each side is given a bonus
181 // based on how many squares inside this area are safe and available for
182 // friendly minor pieces.
183 const Bitboard SpaceMask[] = {
184 (1ULL << SQ_C2) | (1ULL << SQ_D2) | (1ULL << SQ_E2) | (1ULL << SQ_F2) |
185 (1ULL << SQ_C3) | (1ULL << SQ_D3) | (1ULL << SQ_E3) | (1ULL << SQ_F3) |
186 (1ULL << SQ_C4) | (1ULL << SQ_D4) | (1ULL << SQ_E4) | (1ULL << SQ_F4),
187 (1ULL << SQ_C7) | (1ULL << SQ_D7) | (1ULL << SQ_E7) | (1ULL << SQ_F7) |
188 (1ULL << SQ_C6) | (1ULL << SQ_D6) | (1ULL << SQ_E6) | (1ULL << SQ_F6) |
189 (1ULL << SQ_C5) | (1ULL << SQ_D5) | (1ULL << SQ_E5) | (1ULL << SQ_F5)
192 // King danger constants and variables. The king danger scores are taken
193 // from the KingDangerTable[]. Various little "meta-bonuses" measuring
194 // the strength of the enemy attack are added up into an integer, which
195 // is used as an index to KingDangerTable[].
197 // KingAttackWeights[PieceType] contains king attack weights by piece type
198 const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
200 // Bonuses for enemy's safe checks
201 const int QueenContactCheckBonus = 6;
202 const int RookContactCheckBonus = 4;
203 const int QueenCheckBonus = 3;
204 const int RookCheckBonus = 2;
205 const int BishopCheckBonus = 1;
206 const int KnightCheckBonus = 1;
208 // InitKingDanger[Square] contains penalties based on the position of the
209 // defending king, indexed by king's square (from white's point of view).
210 const int InitKingDanger[] = {
211 2, 0, 2, 5, 5, 2, 0, 2,
212 2, 2, 4, 8, 8, 4, 2, 2,
213 7, 10, 12, 12, 12, 12, 10, 7,
214 15, 15, 15, 15, 15, 15, 15, 15,
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
221 // KingDangerTable[Color][attackUnits] contains the actual king danger
222 // weighted scores, indexed by color and by a calculated integer number.
223 Score KingDangerTable[2][128];
225 // TracedTerms[Color][PieceType || TracedType] contains a breakdown of the
226 // evaluation terms, used when tracing.
227 Score TracedTerms[2][16];
228 std::stringstream TraceStream;
231 PST = 8, IMBALANCE = 9, MOBILITY = 10, THREAT = 11,
232 PASSED = 12, UNSTOPPABLE = 13, SPACE = 14, TOTAL = 15
235 // Pawn and material hash tables, indexed by the current thread id.
236 // Note that they will be initialized at 0 being global variables.
237 MaterialInfoTable* MaterialTable[MAX_THREADS];
238 PawnInfoTable* PawnTable[MAX_THREADS];
240 // Function prototypes
241 template<bool HasPopCnt, bool Trace>
242 Value do_evaluate(const Position& pos, Value& margin);
244 template<Color Us, bool HasPopCnt>
245 void init_eval_info(const Position& pos, EvalInfo& ei);
247 template<Color Us, bool HasPopCnt, bool Trace>
248 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility);
250 template<Color Us, bool HasPopCnt, bool Trace>
251 Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]);
254 Score evaluate_threats(const Position& pos, EvalInfo& ei);
256 template<Color Us, bool HasPopCnt>
257 int evaluate_space(const Position& pos, EvalInfo& ei);
260 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
262 template<bool HasPopCnt>
263 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
265 inline Score apply_weight(Score v, Score weight);
266 Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf);
267 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
272 /// prefetchTables() is called in do_move() to prefetch pawn and material
273 /// hash tables data that will be needed shortly after in evaluation.
275 void prefetchTables(Key pKey, Key mKey, int threadID) {
277 PawnTable[threadID]->prefetch(pKey);
278 MaterialTable[threadID]->prefetch(mKey);
282 /// evaluate() is the main evaluation function. It always computes two
283 /// values, an endgame score and a middle game score, and interpolates
284 /// between them based on the remaining material.
285 Value evaluate(const Position& pos, Value& margin) {
287 return CpuHasPOPCNT ? do_evaluate<true, false>(pos, margin)
288 : do_evaluate<false, false>(pos, margin);
293 double to_cp(Value v) { return double(v) / double(PawnValueMidgame); }
295 void trace_add(int idx, Score term_w, Score term_b = Score(0)) {
297 TracedTerms[WHITE][idx] = term_w;
298 TracedTerms[BLACK][idx] = term_b;
301 template<bool HasPopCnt, bool Trace>
302 Value do_evaluate(const Position& pos, Value& margin) {
306 Score mobilityWhite, mobilityBlack;
309 assert(pos.thread() >= 0 && pos.thread() < MAX_THREADS);
310 assert(!pos.is_check());
312 // Initialize value by reading the incrementally updated scores included
313 // in the position object (material + piece square tables).
314 Score bonus = pos.value();
316 // margins[] store the uncertainty estimation of position's evaluation
317 // that typically is used by the search for pruning decisions.
318 margins[WHITE] = margins[BLACK] = VALUE_ZERO;
320 // Probe the material hash table
321 MaterialInfo* mi = MaterialTable[pos.thread()]->get_material_info(pos);
322 bonus += mi->material_value();
324 // If we have a specialized evaluation function for the current material
325 // configuration, call it and return.
326 if (mi->specialized_eval_exists())
329 return mi->evaluate(pos);
332 // Probe the pawn hash table
333 ei.pi = PawnTable[pos.thread()]->get_pawn_info(pos);
334 bonus += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
336 // Initialize attack and king safety bitboards
337 init_eval_info<WHITE, HasPopCnt>(pos, ei);
338 init_eval_info<BLACK, HasPopCnt>(pos, ei);
340 // Evaluate pieces and mobility
341 bonus += evaluate_pieces_of_color<WHITE, HasPopCnt, Trace>(pos, ei, mobilityWhite)
342 - evaluate_pieces_of_color<BLACK, HasPopCnt, Trace>(pos, ei, mobilityBlack);
344 bonus += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
346 // Evaluate kings after all other pieces because we need complete attack
347 // information when computing the king safety evaluation.
348 bonus += evaluate_king<WHITE, HasPopCnt, Trace>(pos, ei, margins)
349 - evaluate_king<BLACK, HasPopCnt, Trace>(pos, ei, margins);
351 // Evaluate tactical threats, we need full attack information including king
352 bonus += evaluate_threats<WHITE>(pos, ei)
353 - evaluate_threats<BLACK>(pos, ei);
355 // Evaluate passed pawns, we need full attack information including king
356 bonus += evaluate_passed_pawns<WHITE>(pos, ei)
357 - evaluate_passed_pawns<BLACK>(pos, ei);
359 // If one side has only a king, check whether exists any unstoppable passed pawn
360 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
362 bonus += evaluate_unstoppable_pawns<HasPopCnt>(pos, ei);
365 trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns<HasPopCnt>(pos, ei));
368 // Evaluate space for both sides, only in middle-game.
369 if (mi->space_weight())
371 int s_w = evaluate_space<WHITE, HasPopCnt>(pos, ei);
372 int s_b = evaluate_space<BLACK, HasPopCnt>(pos, ei);
373 bonus += apply_weight(make_score((s_w - s_b) * mi->space_weight(), 0), Weights[Space]);
376 trace_add(SPACE, apply_weight(make_score(s_w * mi->space_weight(), make_score(0, 0)), Weights[Space]),
377 apply_weight(make_score(s_b * mi->space_weight(), make_score(0, 0)), Weights[Space]));
380 // Scale winning side if position is more drawish that what it appears
381 ScaleFactor sf = eg_value(bonus) > VALUE_DRAW ? mi->scale_factor(pos, WHITE)
382 : mi->scale_factor(pos, BLACK);
383 Phase phase = mi->game_phase();
385 // If we don't already have an unusual scale factor, check for opposite
386 // colored bishop endgames, and use a lower scale for those.
387 if ( phase < PHASE_MIDGAME
388 && pos.opposite_colored_bishops()
389 && sf == SCALE_FACTOR_NORMAL)
391 // Only the two bishops ?
392 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
393 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
395 // Check for KBP vs KB with only a single pawn that is almost
396 // certainly a draw or at least two pawns.
397 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
398 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
401 // Endgame with opposite-colored bishops, but also other pieces. Still
402 // a bit drawish, but not as drawish as with only the two bishops.
403 sf = ScaleFactor(50);
406 // Interpolate between the middle game and the endgame score
407 margin = margins[pos.side_to_move()];
408 Value v = scale_by_game_phase(bonus, phase, sf);
412 trace_add(PST, pos.value());
413 trace_add(IMBALANCE, mi->material_value());
414 trace_add(PAWN, apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]));
415 trace_add(MOBILITY, apply_weight(mobilityWhite, Weights[Mobility]), apply_weight(mobilityBlack, Weights[Mobility]));
416 trace_add(THREAT, evaluate_threats<WHITE>(pos, ei), evaluate_threats<BLACK>(pos, ei));
417 trace_add(PASSED, evaluate_passed_pawns<WHITE>(pos, ei), evaluate_passed_pawns<BLACK>(pos, ei));
418 trace_add(TOTAL, bonus);
419 TraceStream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
420 << ", Black: " << to_cp(margins[BLACK])
421 << "\nScaling: " << std::noshowpos
422 << std::setw(6) << 100.0 * phase/128.0 << "% MG, "
423 << std::setw(6) << 100.0 * (1.0 - phase/128.0) << "% * "
424 << std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
425 << "Total evaluation: " << to_cp(v);
428 return pos.side_to_move() == WHITE ? v : -v;
434 /// init_eval() initializes various tables used by the evaluation function
436 void init_eval(int threads) {
438 assert(threads <= MAX_THREADS);
440 for (int i = 0; i < MAX_THREADS; i++)
445 delete MaterialTable[i];
447 MaterialTable[i] = NULL;
451 PawnTable[i] = new PawnInfoTable();
453 if (!MaterialTable[i])
454 MaterialTable[i] = new MaterialInfoTable();
459 /// quit_eval() releases heap-allocated memory at program termination
467 /// read_weights() reads evaluation weights from the corresponding UCI parameters
469 void read_evaluation_uci_options(Color us) {
471 // King safety is asymmetrical. Our king danger level is weighted by
472 // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
473 const int kingDangerUs = (us == WHITE ? KingDangerUs : KingDangerThem);
474 const int kingDangerThem = (us == WHITE ? KingDangerThem : KingDangerUs);
476 Weights[Mobility] = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
477 Weights[PawnStructure] = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
478 Weights[PassedPawns] = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
479 Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
480 Weights[kingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
481 Weights[kingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
483 // If running in analysis mode, make sure we use symmetrical king safety. We do this
484 // by replacing both Weights[kingDangerUs] and Weights[kingDangerThem] by their average.
485 if (Options["UCI_AnalyseMode"].value<bool>())
486 Weights[kingDangerUs] = Weights[kingDangerThem] = (Weights[kingDangerUs] + Weights[kingDangerThem]) / 2;
494 // init_eval_info() initializes king bitboards for given color adding
495 // pawn attacks. To be done at the beginning of the evaluation.
497 template<Color Us, bool HasPopCnt>
498 void init_eval_info(const Position& pos, EvalInfo& ei) {
500 const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
501 const Color Them = (Us == WHITE ? BLACK : WHITE);
503 Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
504 ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
506 // Init king safety tables only if we are going to use them
507 if ( pos.piece_count(Us, QUEEN)
508 && pos.non_pawn_material(Us) >= QueenValueMidgame + RookValueMidgame)
510 ei.kingZone[Us] = (b | (Us == WHITE ? b >> 8 : b << 8));
511 b &= ei.attackedBy[Us][PAWN];
512 ei.kingAttackersCount[Us] = b ? count_1s<Max15>(b) / 2 : 0;
513 ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
515 ei.kingZone[Us] = ei.kingAttackersCount[Us] = 0;
519 // evaluate_outposts() evaluates bishop and knight outposts squares
521 template<PieceType Piece, Color Us>
522 Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
524 const Color Them = (Us == WHITE ? BLACK : WHITE);
526 assert (Piece == BISHOP || Piece == KNIGHT);
528 // Initial bonus based on square
529 Value bonus = OutpostBonus[Piece == BISHOP][relative_square(Us, s)];
531 // Increase bonus if supported by pawn, especially if the opponent has
532 // no minor piece which can exchange the outpost piece.
533 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
535 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
536 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
537 bonus += bonus + bonus / 2;
541 return make_score(bonus, bonus);
545 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
547 template<PieceType Piece, Color Us, bool HasPopCnt, bool Trace>
548 Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
554 Score bonus = SCORE_ZERO;
556 const BitCountType Full = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64 : CNT32;
557 const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
558 const Color Them = (Us == WHITE ? BLACK : WHITE);
559 const Square* ptr = pos.piece_list_begin(Us, Piece);
561 ei.attackedBy[Us][Piece] = EmptyBoardBB;
563 while ((s = *ptr++) != SQ_NONE)
565 // Find attacked squares, including x-ray attacks for bishops and rooks
566 if (Piece == KNIGHT || Piece == QUEEN)
567 b = pos.attacks_from<Piece>(s);
568 else if (Piece == BISHOP)
569 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
570 else if (Piece == ROOK)
571 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
575 // Update attack info
576 ei.attackedBy[Us][Piece] |= b;
579 if (b & ei.kingZone[Us])
581 ei.kingAttackersCount[Us]++;
582 ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
583 Bitboard bb = (b & ei.attackedBy[Them][KING]);
585 ei.kingAdjacentZoneAttacksCount[Us] += count_1s<Max15>(bb);
589 mob = (Piece != QUEEN ? count_1s<Max15>(b & mobilityArea)
590 : count_1s<Full >(b & mobilityArea));
592 mobility += MobilityBonus[Piece][mob];
594 // Decrease score if we are attacked by an enemy pawn. Remaining part
595 // of threat evaluation must be done later when we have full attack info.
596 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
597 bonus -= ThreatedByPawnPenalty[Piece];
599 // Bishop and knight outposts squares
600 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Us))
601 bonus += evaluate_outposts<Piece, Us>(pos, ei, s);
603 // Queen or rook on 7th rank
604 if ( (Piece == ROOK || Piece == QUEEN)
605 && relative_rank(Us, s) == RANK_7
606 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
608 bonus += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
611 // Special extra evaluation for bishops
612 if (Piece == BISHOP && pos.is_chess960())
614 // An important Chess960 pattern: A cornered bishop blocked by
615 // a friendly pawn diagonally in front of it is a very serious
616 // problem, especially when that pawn is also blocked.
617 if (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1))
619 Square d = pawn_push(Us) + (square_file(s) == FILE_A ? DELTA_E : DELTA_W);
620 if (pos.piece_on(s + d) == make_piece(Us, PAWN))
622 if (!pos.square_is_empty(s + d + pawn_push(Us)))
623 bonus -= 2*TrappedBishopA1H1Penalty;
624 else if (pos.piece_on(s + 2*d) == make_piece(Us, PAWN))
625 bonus -= TrappedBishopA1H1Penalty;
627 bonus -= TrappedBishopA1H1Penalty / 2;
632 // Special extra evaluation for rooks
635 // Open and half-open files
637 if (ei.pi->file_is_half_open(Us, f))
639 if (ei.pi->file_is_half_open(Them, f))
640 bonus += RookOpenFileBonus;
642 bonus += RookHalfOpenFileBonus;
645 // Penalize rooks which are trapped inside a king. Penalize more if
646 // king has lost right to castle.
647 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
650 ksq = pos.king_square(Us);
652 if ( square_file(ksq) >= FILE_E
653 && square_file(s) > square_file(ksq)
654 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
656 // Is there a half-open file between the king and the edge of the board?
657 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
658 bonus -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
659 : (TrappedRookPenalty - mob * 16), 0);
661 else if ( square_file(ksq) <= FILE_D
662 && square_file(s) < square_file(ksq)
663 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
665 // Is there a half-open file between the king and the edge of the board?
666 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
667 bonus -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
668 : (TrappedRookPenalty - mob * 16), 0);
674 TracedTerms[Us][Piece] = bonus;
680 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
681 // and the type of attacked one.
684 Score evaluate_threats(const Position& pos, EvalInfo& ei) {
686 const Color Them = (Us == WHITE ? BLACK : WHITE);
689 Score bonus = SCORE_ZERO;
691 // Enemy pieces not defended by a pawn and under our attack
692 Bitboard weakEnemies = pos.pieces_of_color(Them)
693 & ~ei.attackedBy[Them][PAWN]
694 & ei.attackedBy[Us][0];
698 // Add bonus according to type of attacked enemy piece and to the
699 // type of attacking piece, from knights to queens. Kings are not
700 // considered because are already handled in king evaluation.
701 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
703 b = ei.attackedBy[Us][pt1] & weakEnemies;
705 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
706 if (b & pos.pieces(pt2))
707 bonus += ThreatBonus[pt1][pt2];
713 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
714 // pieces of a given color.
716 template<Color Us, bool HasPopCnt, bool Trace>
717 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
719 const Color Them = (Us == WHITE ? BLACK : WHITE);
721 Score bonus = mobility = SCORE_ZERO;
723 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
724 const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
726 bonus += evaluate_pieces<KNIGHT, Us, HasPopCnt, Trace>(pos, ei, mobility, mobilityArea);
727 bonus += evaluate_pieces<BISHOP, Us, HasPopCnt, Trace>(pos, ei, mobility, mobilityArea);
728 bonus += evaluate_pieces<ROOK, Us, HasPopCnt, Trace>(pos, ei, mobility, mobilityArea);
729 bonus += evaluate_pieces<QUEEN, Us, HasPopCnt, Trace>(pos, ei, mobility, mobilityArea);
731 // Sum up all attacked squares
732 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
733 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
734 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
739 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
741 template<Color Us, bool HasPopCnt, bool Trace>
742 Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) {
744 const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
745 const Color Them = (Us == WHITE ? BLACK : WHITE);
747 Bitboard undefended, b, b1, b2, safe;
749 const Square ksq = pos.king_square(Us);
752 Score bonus = ei.pi->king_shelter<Us>(pos, ksq);
754 // King safety. This is quite complicated, and is almost certainly far
755 // from optimally tuned.
756 if ( ei.kingAttackersCount[Them] >= 2
757 && ei.kingAdjacentZoneAttacksCount[Them])
759 // Find the attacked squares around the king which has no defenders
760 // apart from the king itself
761 undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
762 undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
763 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
764 | ei.attackedBy[Us][QUEEN]);
766 // Initialize the 'attackUnits' variable, which is used later on as an
767 // index to the KingDangerTable[] array. The initial value is based on
768 // the number and types of the enemy's attacking pieces, the number of
769 // attacked and undefended squares around our king, the square of the
770 // king, and the quality of the pawn shelter.
771 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
772 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s<Max15>(undefended))
773 + InitKingDanger[relative_square(Us, ksq)]
774 - mg_value(ei.pi->king_shelter<Us>(pos, ksq)) / 32;
776 // Analyse enemy's safe queen contact checks. First find undefended
777 // squares around the king attacked by enemy queen...
778 b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces_of_color(Them);
781 // ...then remove squares not supported by another enemy piece
782 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
783 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
785 attackUnits += QueenContactCheckBonus
787 * (Them == pos.side_to_move() ? 2 : 1);
790 // Analyse enemy's safe rook contact checks. First find undefended
791 // squares around the king attacked by enemy rooks...
792 b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces_of_color(Them);
794 // Consider only squares where the enemy rook gives check
795 b &= RookPseudoAttacks[ksq];
799 // ...then remove squares not supported by another enemy piece
800 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
801 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
803 attackUnits += RookContactCheckBonus
805 * (Them == pos.side_to_move() ? 2 : 1);
808 // Analyse enemy's safe distance checks for sliders and knights
809 safe = ~(pos.pieces_of_color(Them) | ei.attackedBy[Us][0]);
811 b1 = pos.attacks_from<ROOK>(ksq) & safe;
812 b2 = pos.attacks_from<BISHOP>(ksq) & safe;
814 // Enemy queen safe checks
815 b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
817 attackUnits += QueenCheckBonus * count_1s<Max15>(b);
819 // Enemy rooks safe checks
820 b = b1 & ei.attackedBy[Them][ROOK];
822 attackUnits += RookCheckBonus * count_1s<Max15>(b);
824 // Enemy bishops safe checks
825 b = b2 & ei.attackedBy[Them][BISHOP];
827 attackUnits += BishopCheckBonus * count_1s<Max15>(b);
829 // Enemy knights safe checks
830 b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
832 attackUnits += KnightCheckBonus * count_1s<Max15>(b);
834 // To index KingDangerTable[] attackUnits must be in [0, 99] range
835 attackUnits = Min(99, Max(0, attackUnits));
837 // Finally, extract the king danger score from the KingDangerTable[]
838 // array and subtract the score from evaluation. Set also margins[]
839 // value that will be used for pruning because this value can sometimes
840 // be very big, and so capturing a single attacking piece can therefore
841 // result in a score change far bigger than the value of the captured piece.
842 bonus -= KingDangerTable[Us][attackUnits];
843 margins[Us] += mg_value(KingDangerTable[Us][attackUnits]);
847 TracedTerms[Us][KING] = bonus;
853 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
856 Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
858 const Color Them = (Us == WHITE ? BLACK : WHITE);
860 Score bonus = SCORE_ZERO;
861 Bitboard squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
862 Bitboard b = ei.pi->passed_pawns(Us);
868 Square s = pop_1st_bit(&b);
870 assert(pos.pawn_is_passed(Us, s));
872 int r = int(relative_rank(Us, s) - RANK_2);
873 int rr = r * (r - 1);
875 // Base bonus based on rank
876 Value mbonus = Value(20 * rr);
877 Value ebonus = Value(10 * (rr + r + 1));
881 Square blockSq = s + pawn_push(Us);
883 // Adjust bonus based on kings proximity
884 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * rr);
885 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
886 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * rr);
888 // If the pawn is free to advance, increase bonus
889 if (pos.square_is_empty(blockSq))
891 squaresToQueen = squares_in_front_of(Us, s);
892 defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
894 // If there is an enemy rook or queen attacking the pawn from behind,
895 // add all X-ray attacks by the rook or queen. Otherwise consider only
896 // the squares in the pawn's path attacked or occupied by the enemy.
897 if ( (squares_in_front_of(Them, s) & pos.pieces(ROOK, QUEEN, Them))
898 && (squares_in_front_of(Them, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<ROOK>(s)))
899 unsafeSquares = squaresToQueen;
901 unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces_of_color(Them));
903 // If there aren't enemy attacks or pieces along the path to queen give
904 // huge bonus. Even bigger if we protect the pawn's path.
906 ebonus += Value(rr * (squaresToQueen == defendedSquares ? 17 : 15));
908 // OK, there are enemy attacks or pieces (but not pawns). Are those
909 // squares which are attacked by the enemy also attacked by us ?
910 // If yes, big bonus (but smaller than when there are no enemy attacks),
911 // if no, somewhat smaller bonus.
912 ebonus += Value(rr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
914 // At last, add a small bonus when there are no *friendly* pieces
915 // in the pawn's path.
916 if (!(squaresToQueen & pos.pieces_of_color(Us)))
921 // Increase the bonus if the passed pawn is supported by a friendly pawn
922 // on the same rank and a bit smaller if it's on the previous rank.
923 supportingPawns = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
924 if (supportingPawns & rank_bb(s))
925 ebonus += Value(r * 20);
926 else if (supportingPawns & rank_bb(s - pawn_push(Us)))
927 ebonus += Value(r * 12);
929 // Rook pawns are a special case: They are sometimes worse, and
930 // sometimes better than other passed pawns. It is difficult to find
931 // good rules for determining whether they are good or bad. For now,
932 // we try the following: Increase the value for rook pawns if the
933 // other side has no pieces apart from a knight, and decrease the
934 // value if the other side has a rook or queen.
935 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
937 if (pos.non_pawn_material(Them) <= KnightValueMidgame)
938 ebonus += ebonus / 4;
939 else if (pos.pieces(ROOK, QUEEN, Them))
940 ebonus -= ebonus / 4;
942 bonus += make_score(mbonus, ebonus);
946 // Add the scores to the middle game and endgame eval
947 return apply_weight(bonus, Weights[PassedPawns]);
950 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides
951 template<bool HasPopCnt>
952 Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
954 const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
956 // Step 1. Hunt for unstoppable pawns. If we find at least one, record how many plies
957 // are required for promotion
958 int pliesToGo[2] = {256, 256};
960 for (Color c = WHITE; c <= BLACK; c++)
962 // Skip if other side has non-pawn pieces
963 if (pos.non_pawn_material(opposite_color(c)))
966 Bitboard b = ei.pi->passed_pawns(c);
970 Square s = pop_1st_bit(&b);
971 Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8));
973 int mtg = RANK_8 - relative_rank(c, s) - int(relative_rank(c, s) == RANK_2);
974 int oppmtg = square_distance(pos.king_square(opposite_color(c)), queeningSquare) - int(c != pos.side_to_move());
975 bool pathDefended = ((ei.attackedBy[c][0] & squares_in_front_of(c, s)) == squares_in_front_of(c, s));
977 if (mtg >= oppmtg && !pathDefended)
980 int blockerCount = count_1s<Max15>(squares_in_front_of(c, s) & pos.occupied_squares());
983 if (mtg >= oppmtg && !pathDefended)
986 int ptg = 2 * mtg - int(c == pos.side_to_move());
988 if (ptg < pliesToGo[c])
993 // Step 2. If either side cannot promote at least three plies before the other side then
994 // situation becomes too complex and we give up. Otherwise we determine the possibly "winning side"
995 if (abs(pliesToGo[WHITE] - pliesToGo[BLACK]) < 3)
996 return make_score(0, 0);
998 Color winnerSide = (pliesToGo[WHITE] < pliesToGo[BLACK] ? WHITE : BLACK);
999 Color loserSide = opposite_color(winnerSide);
1001 // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
1002 // We collect the potential candidates in potentialBB.
1003 Bitboard pawnBB = pos.pieces(PAWN, loserSide);
1004 Bitboard potentialBB = pawnBB;
1005 const Bitboard passedBB = ei.pi->passed_pawns(loserSide);
1009 Square psq = pop_1st_bit(&pawnBB);
1011 // Check direct advancement
1012 int mtg = RANK_8 - relative_rank(loserSide, psq) - int(relative_rank(loserSide, psq) == RANK_2);
1013 int ptg = 2 * mtg - int(loserSide == pos.side_to_move());
1015 // Check if (without even considering any obstacles) we're too far away
1016 if (pliesToGo[winnerSide] + 3 <= ptg)
1018 clear_bit(&potentialBB, psq);
1022 // If this is passed pawn, then it _may_ promote in time. We give up.
1023 if (bit_is_set(passedBB, psq))
1024 return make_score(0, 0);
1026 // Doubled pawn is worthless
1027 if (squares_in_front_of(loserSide, psq) & (pos.pieces(PAWN, loserSide)))
1029 clear_bit(&potentialBB, psq);
1034 // Step 4. Check new passed pawn creation through king capturing and sacrifises
1035 pawnBB = potentialBB;
1039 Square psq = pop_1st_bit(&pawnBB);
1041 int mtg = RANK_8 - relative_rank(loserSide, psq) - int(relative_rank(loserSide, psq) == RANK_2);
1042 int ptg = 2 * mtg - int(loserSide == pos.side_to_move());
1044 // Generate list of obstacles
1045 Bitboard obsBB = passed_pawn_mask(loserSide, psq) & pos.pieces(PAWN, winnerSide);
1046 const bool pawnIsOpposed = squares_in_front_of(loserSide, psq) & obsBB;
1049 // How many plies does it take to remove all the obstacles?
1051 int realObsCount = 0;
1052 int minKingDist = 256;
1056 Square obSq = pop_1st_bit(&obsBB);
1059 // Check pawns that can give support to overcome obstacle (Eg. wp: a4,b4 bp: b2. b4 is giving support)
1060 if (!pawnIsOpposed && square_file(psq) != square_file(obSq))
1062 Bitboard supBB = in_front_bb(winnerSide, Square(obSq + (winnerSide == WHITE ? 8 : -8)))
1063 & neighboring_files_bb(psq) & potentialBB;
1065 while(supBB) // This while-loop could be replaced with supSq = LSB/MSB(supBB) (depending on color)
1067 Square supSq = pop_1st_bit(&supBB);
1068 int dist = square_distance(obSq, supSq);
1069 minMoves = Min(minMoves, dist - 2);
1074 // Check pawns that can be sacrifised
1075 Bitboard sacBB = passed_pawn_mask(winnerSide, obSq) & neighboring_files_bb(obSq) & potentialBB & ~(1ULL << psq);
1077 while(sacBB) // This while-loop could be replaced with sacSq = LSB/MSB(sacBB) (depending on color)
1079 Square sacSq = pop_1st_bit(&sacBB);
1080 int dist = square_distance(obSq, sacSq);
1081 minMoves = Min(minMoves, dist - 2);
1084 // If obstacle can be destroyed with immediate pawn sacrifise, it's not real obstacle
1088 // Pawn sac calculations
1089 sacptg += minMoves * 2;
1091 // King capture calc
1093 int kingDist = square_distance(pos.king_square(loserSide), obSq);
1094 minKingDist = Min(minKingDist, kingDist);
1097 // Check if pawn sac plan _may_ save the day
1098 if (pliesToGo[winnerSide] + 3 > ptg + sacptg)
1099 return make_score(0, 0);
1101 // Check if king capture plan _may_ save the day (contains some false positives)
1102 int kingptg = (minKingDist + realObsCount) * 2;
1103 if (pliesToGo[winnerSide] + 3 > ptg + kingptg)
1104 return make_score(0, 0);
1107 // Step 5. Assign bonus
1108 const int Sign[2] = {1, -1};
1109 return Sign[winnerSide] * make_score(0, (Value) 0x500 - 0x20 * pliesToGo[winnerSide]);
1113 // evaluate_space() computes the space evaluation for a given side. The
1114 // space evaluation is a simple bonus based on the number of safe squares
1115 // available for minor pieces on the central four files on ranks 2--4. Safe
1116 // squares one, two or three squares behind a friendly pawn are counted
1117 // twice. Finally, the space bonus is scaled by a weight taken from the
1118 // material hash table. The aim is to improve play on game opening.
1119 template<Color Us, bool HasPopCnt>
1120 int evaluate_space(const Position& pos, EvalInfo& ei) {
1122 const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
1123 const Color Them = (Us == WHITE ? BLACK : WHITE);
1125 // Find the safe squares for our pieces inside the area defined by
1126 // SpaceMask[]. A square is unsafe if it is attacked by an enemy
1127 // pawn, or if it is undefended and attacked by an enemy piece.
1128 Bitboard safe = SpaceMask[Us]
1129 & ~pos.pieces(PAWN, Us)
1130 & ~ei.attackedBy[Them][PAWN]
1131 & (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
1133 // Find all squares which are at most three squares behind some friendly pawn
1134 Bitboard behind = pos.pieces(PAWN, Us);
1135 behind |= (Us == WHITE ? behind >> 8 : behind << 8);
1136 behind |= (Us == WHITE ? behind >> 16 : behind << 16);
1138 return count_1s<Max15>(safe) + count_1s<Max15>(behind & safe);
1142 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1144 inline Score apply_weight(Score v, Score w) {
1145 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
1146 (int(eg_value(v)) * eg_value(w)) / 0x100);
1150 // scale_by_game_phase() interpolates between a middle game and an endgame score,
1151 // based on game phase. It also scales the return value by a ScaleFactor array.
1153 Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf) {
1155 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1156 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1157 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1159 int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
1160 int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
1161 return Value((result + GrainSize / 2) & ~(GrainSize - 1));
1165 // weight_option() computes the value of an evaluation weight, by combining
1166 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1168 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1170 // Scale option value from 100 to 256
1171 int mg = Options[mgOpt].value<int>() * 256 / 100;
1172 int eg = Options[egOpt].value<int>() * 256 / 100;
1174 return apply_weight(make_score(mg, eg), internalWeight);
1178 // init_safety() initizes the king safety evaluation, based on UCI
1179 // parameters. It is called from read_weights().
1181 void init_safety() {
1183 const Value MaxSlope = Value(30);
1184 const Value Peak = Value(1280);
1187 // First setup the base table
1188 for (int i = 0; i < 100; i++)
1190 t[i] = Value(int(0.4 * i * i));
1193 t[i] = Min(t[i], t[i - 1] + MaxSlope);
1195 t[i] = Min(t[i], Peak);
1198 // Then apply the weights and get the final KingDangerTable[] array
1199 for (Color c = WHITE; c <= BLACK; c++)
1200 for (int i = 0; i < 100; i++)
1201 KingDangerTable[c][i] = apply_weight(make_score(t[i], 0), Weights[KingDangerUs + c]);
1205 // trace_row() is an helper function used by tracing code to register the
1206 // values of a single evaluation term.
1208 void trace_row(const char *name, int idx) {
1210 Score term_w = TracedTerms[WHITE][idx];
1211 Score term_b = TracedTerms[BLACK][idx];
1214 case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
1215 TraceStream << std::setw(20) << name << " | --- --- | --- --- | "
1216 << std::setw(6) << to_cp(mg_value(term_w)) << " "
1217 << std::setw(6) << to_cp(eg_value(term_w)) << " \n";
1220 TraceStream << std::setw(20) << name << " | " << std::noshowpos
1221 << std::setw(5) << to_cp(mg_value(term_w)) << " "
1222 << std::setw(5) << to_cp(eg_value(term_w)) << " | "
1223 << std::setw(5) << to_cp(mg_value(term_b)) << " "
1224 << std::setw(5) << to_cp(eg_value(term_b)) << " | "
1226 << std::setw(6) << to_cp(mg_value(term_w - term_b)) << " "
1227 << std::setw(6) << to_cp(eg_value(term_w - term_b)) << " \n";
1233 /// trace_evaluate() is like evaluate() but instead of a value returns a string
1234 /// suitable to be print on stdout with the detailed descriptions and values of
1235 /// each evaluation term. Used mainly for debugging.
1237 std::string trace_evaluate(const Position& pos) {
1242 TraceStream.str("");
1243 TraceStream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
1244 memset(TracedTerms, 0, 2 * 16 * sizeof(Score));
1246 do_evaluate<false, true>(pos, margin);
1248 totals = TraceStream.str();
1249 TraceStream.str("");
1251 TraceStream << std::setw(21) << "Eval term " << "| White | Black | Total \n"
1252 << " | MG EG | MG EG | MG EG \n"
1253 << "---------------------+-------------+-------------+---------------\n";
1255 trace_row("Material, PST, Tempo", PST);
1256 trace_row("Material imbalance", IMBALANCE);
1257 trace_row("Pawns", PAWN);
1258 trace_row("Knights", KNIGHT);
1259 trace_row("Bishops", BISHOP);
1260 trace_row("Rooks", ROOK);
1261 trace_row("Queens", QUEEN);
1262 trace_row("Mobility", MOBILITY);
1263 trace_row("King safety", KING);
1264 trace_row("Threats", THREAT);
1265 trace_row("Passed pawns", PASSED);
1266 trace_row("Unstoppable pawns", UNSTOPPABLE);
1267 trace_row("Space", SPACE);
1269 TraceStream << "---------------------+-------------+-------------+---------------\n";
1270 trace_row("Total", TOTAL);
1271 TraceStream << totals;
1273 return TraceStream.str();