2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2009 Marco Costalba
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/>.
34 #include "ucioption.h"
38 //// Local definitions
43 const int Sign[2] = { 1, -1 };
45 // Evaluation grain size, must be a power of 2
46 const int GrainSize = 8;
48 // Evaluation weights, initialized from UCI options
49 int WeightMobilityMidgame, WeightMobilityEndgame;
50 int WeightPawnStructureMidgame, WeightPawnStructureEndgame;
51 int WeightPassedPawnsMidgame, WeightPassedPawnsEndgame;
52 int WeightKingSafety[2];
55 // Internal evaluation weights. These are applied on top of the evaluation
56 // weights read from UCI parameters. The purpose is to be able to change
57 // the evaluation weights while keeping the default values of the UCI
58 // parameters at 100, which looks prettier.
60 // Values modified by Joona Kiiski
61 const int WeightMobilityMidgameInternal = 248;
62 const int WeightMobilityEndgameInternal = 271;
63 const int WeightPawnStructureMidgameInternal = 233;
64 const int WeightPawnStructureEndgameInternal = 201;
65 const int WeightPassedPawnsMidgameInternal = 252;
66 const int WeightPassedPawnsEndgameInternal = 259;
67 const int WeightKingSafetyInternal = 247;
68 const int WeightKingOppSafetyInternal = 259;
69 const int WeightSpaceInternal = 46;
71 // Mobility and outposts bonus modified by Joona Kiiski
73 // Visually better to define tables constants
76 // Knight mobility bonus in middle game and endgame, indexed by the number
77 // of attacked squares not occupied by friendly piecess.
78 const Value MidgameKnightMobilityBonus[] = {
80 V(-38), V(-25),V(-12), V(0), V(12), V(25), V(31), V(38), V(38)
83 const Value EndgameKnightMobilityBonus[] = {
85 V(-33), V(-23),V(-13), V(-3), V(7), V(17), V(22), V(27), V(27)
88 // Bishop mobility bonus in middle game and endgame, indexed by the number
89 // of attacked squares not occupied by friendly pieces. X-ray attacks through
90 // queens are also included.
91 const Value MidgameBishopMobilityBonus[] = {
93 V(-25), V(-11), V(3), V(17), V(31), V(45), V(57), V(65),
94 // 8 9 10 11 12 13 14 15
95 V( 71), V( 74), V(76), V(78), V(79), V(80), V(81), V(81)
98 const Value EndgameBishopMobilityBonus[] = {
100 V(-30), V(-16), V(-2), V(12), V(26), V(40), V(52), V(60),
101 // 8 9 10 11 12 13 14 15
102 V( 65), V( 69), V(71), V(73), V(74), V(75), V(76), V(76)
105 // Rook mobility bonus in middle game and endgame, indexed by the number
106 // of attacked squares not occupied by friendly pieces. X-ray attacks through
107 // queens and rooks are also included.
108 const Value MidgameRookMobilityBonus[] = {
110 V(-20), V(-14), V(-8), V(-2), V(4), V(10), V(14), V(19),
111 // 8 9 10 11 12 13 14 15
112 V( 23), V( 26), V(27), V(28), V(29), V(30), V(31), V(32)
115 const Value EndgameRookMobilityBonus[] = {
117 V(-36), V(-19), V(-3), V(13), V(29), V(46), V(62), V(79),
118 // 8 9 10 11 12 13 14 15
119 V( 95), V(106),V(111),V(114),V(116),V(117),V(118),V(118)
122 // Queen mobility bonus in middle game and endgame, indexed by the number
123 // of attacked squares not occupied by friendly pieces.
124 const Value MidgameQueenMobilityBonus[] = {
126 V(-10), V(-8), V(-6), V(-3), V(-1), V( 1), V( 3), V( 5),
127 // 8 9 10 11 12 13 14 15
128 V( 8), V(10), V(12), V(15), V(16), V(17), V(18), V(20),
129 // 16 17 18 19 20 21 22 23
130 V( 20), V(20), V(20), V(20), V(20), V(20), V(20), V(20),
131 // 24 25 26 27 28 29 30 31
132 V( 20), V(20), V(20), V(20), V(20), V(20), V(20), V(20)
135 const Value EndgameQueenMobilityBonus[] = {
137 V(-18),V(-13), V(-7), V(-2), V( 3), V (8), V(13), V(19),
138 // 8 9 10 11 12 13 14 15
139 V( 23), V(27), V(32), V(34), V(35), V(35), V(35), V(35),
140 // 16 17 18 19 20 21 22 23
141 V( 35), V(35), V(35), V(35), V(35), V(35), V(35), V(35),
142 // 24 25 26 27 28 29 30 31
143 V( 35), V(35), V(35), V(35), V(35), V(35), V(35), V(35)
146 // Outpost bonuses for knights and bishops, indexed by square (from white's
148 const Value KnightOutpostBonus[64] = {
150 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
151 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
152 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
153 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
154 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
155 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
156 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
157 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
160 const Value BishopOutpostBonus[64] = {
162 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
163 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
164 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
165 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
166 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
167 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
168 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
169 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
172 // Bonus for unstoppable passed pawns
173 const Value UnstoppablePawnValue = Value(0x500);
175 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
176 const Value MidgameRookOn7thBonus = Value(47);
177 const Value EndgameRookOn7thBonus = Value(98);
178 const Value MidgameQueenOn7thBonus = Value(27);
179 const Value EndgameQueenOn7thBonus = Value(54);
181 // Rooks on open files (modified by Joona Kiiski)
182 const Value RookOpenFileBonus = Value(43);
183 const Value RookHalfOpenFileBonus = Value(19);
185 // Penalty for rooks trapped inside a friendly king which has lost the
187 const Value TrappedRookPenalty = Value(180);
189 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
191 const Value TrappedBishopA7H7Penalty = Value(300);
193 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
194 const Bitboard MaskA7H7[2] = {
195 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
196 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
199 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
200 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
201 // happen in Chess960 games.
202 const Value TrappedBishopA1H1Penalty = Value(100);
204 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
205 const Bitboard MaskA1H1[2] = {
206 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
207 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
210 // The SpaceMask[color] contains the area of the board which is considered
211 // by the space evaluation. In the middle game, each side is given a bonus
212 // based on how many squares inside this area are safe and available for
213 // friendly minor pieces.
214 const Bitboard SpaceMask[2] = {
215 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
216 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
217 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
218 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
219 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
220 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
223 /// King safety constants and variables. The king safety scores are taken
224 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
225 /// the strength of the attack are added up into an integer, which is used
226 /// as an index to SafetyTable[].
228 // Attack weights for each piece type
229 const int QueenAttackWeight = 5;
230 const int RookAttackWeight = 3;
231 const int BishopAttackWeight = 2;
232 const int KnightAttackWeight = 2;
234 // Bonuses for safe checks, initialized from UCI options
235 int QueenContactCheckBonus, DiscoveredCheckBonus;
236 int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
238 // Scan for queen contact mates?
239 const bool QueenContactMates = true;
241 // Bonus for having a mate threat, initialized from UCI options
244 // InitKingDanger[] contains bonuses based on the position of the defending
246 const int InitKingDanger[64] = {
247 2, 0, 2, 5, 5, 2, 0, 2,
248 2, 2, 4, 8, 8, 4, 2, 2,
249 7, 10, 12, 12, 12, 12, 10, 7,
250 15, 15, 15, 15, 15, 15, 15, 15,
251 15, 15, 15, 15, 15, 15, 15, 15,
252 15, 15, 15, 15, 15, 15, 15, 15,
253 15, 15, 15, 15, 15, 15, 15, 15,
254 15, 15, 15, 15, 15, 15, 15, 15
257 // SafetyTable[] contains the actual king safety scores. It is initialized
259 Value SafetyTable[100];
261 // Pawn and material hash tables, indexed by the current thread id
262 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
263 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
265 // Sizes of pawn and material hash tables
266 const int PawnTableSize = 16384;
267 const int MaterialTableSize = 1024;
269 // Function prototypes
270 template<bool HasPopCnt>
271 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
273 template<Color Us, bool HasPopCnt>
274 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
276 template<Color Us, bool HasPopCnt>
277 void evaluate_king(const Position& pos, EvalInfo& ei);
279 template<Color Us, bool HasPopCnt>
280 void evaluate_space(const Position& pos, EvalInfo& ei);
282 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
283 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
284 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
285 inline Value apply_weight(Value v, int w);
286 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
287 int weight_option(const std::string& opt, int weight);
296 /// evaluate() is the main evaluation function. It always computes two
297 /// values, an endgame score and a middle game score, and interpolates
298 /// between them based on the remaining material.
299 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
301 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
302 : do_evaluate<false>(pos, ei, threadID);
307 template<bool HasPopCnt>
308 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
311 assert(threadID >= 0 && threadID < THREAD_MAX);
313 memset(&ei, 0, sizeof(EvalInfo));
315 // Initialize by reading the incrementally updated scores included in the
316 // position object (material + piece square tables)
317 ei.mgValue = pos.mg_value();
318 ei.egValue = pos.eg_value();
320 // Probe the material hash table
321 ei.mi = MaterialTable[threadID]->get_material_info(pos);
322 ei.mgValue += ei.mi->material_value();
323 ei.egValue += ei.mi->material_value();
325 // If we have a specialized evaluation function for the current material
326 // configuration, call it and return
327 if (ei.mi->specialized_eval_exists())
328 return ei.mi->evaluate(pos);
330 // After get_material_info() call that modifies them
331 ScaleFactor factor[2];
332 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
333 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
335 // Probe the pawn hash table
336 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
337 ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
338 ei.egValue += apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame);
340 // Initialize king attack bitboards and king attack zones for both sides
341 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
342 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
343 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
344 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
346 // Initialize pawn attack bitboards for both sides
347 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
348 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
349 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
350 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
352 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
355 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
358 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
359 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
361 // Kings. Kings are evaluated after all other pieces for both sides,
362 // because we need complete attack information for all pieces when computing
363 // the king safety evaluation.
364 evaluate_king<WHITE, HasPopCnt>(pos, ei);
365 evaluate_king<BLACK, HasPopCnt>(pos, ei);
367 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
368 // because we need to know which side promotes first in positions where
369 // both sides have an unstoppable passed pawn. To be called after all attacks
370 // are computed, included king.
371 if (ei.pi->passed_pawns())
372 evaluate_passed_pawns(pos, ei);
374 Phase phase = pos.game_phase();
376 // Middle-game specific evaluation terms
377 if (phase > PHASE_ENDGAME)
379 // Pawn storms in positions with opposite castling.
380 if ( square_file(pos.king_square(WHITE)) >= FILE_E
381 && square_file(pos.king_square(BLACK)) <= FILE_D)
383 ei.mgValue += ei.pi->queenside_storm_value(WHITE)
384 - ei.pi->kingside_storm_value(BLACK);
386 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
387 && square_file(pos.king_square(BLACK)) >= FILE_E)
389 ei.mgValue += ei.pi->kingside_storm_value(WHITE)
390 - ei.pi->queenside_storm_value(BLACK);
392 // Evaluate space for both sides
393 if (ei.mi->space_weight() > 0)
395 evaluate_space<WHITE, HasPopCnt>(pos, ei);
396 evaluate_space<BLACK, HasPopCnt>(pos, ei);
401 ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
402 ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
404 // If we don't already have an unusual scale factor, check for opposite
405 // colored bishop endgames, and use a lower scale for those
406 if ( phase < PHASE_MIDGAME
407 && pos.opposite_colored_bishops()
408 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
409 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
413 // Only the two bishops ?
414 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
415 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
417 // Check for KBP vs KB with only a single pawn that is almost
418 // certainly a draw or at least two pawns.
419 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
420 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
423 // Endgame with opposite-colored bishops, but also other pieces. Still
424 // a bit drawish, but not as drawish as with only the two bishops.
425 sf = ScaleFactor(50);
427 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
429 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
433 // Interpolate between the middle game and the endgame score
434 Color stm = pos.side_to_move();
436 Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
438 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
443 /// quick_evaluate() does a very approximate evaluation of the current position.
444 /// It currently considers only material and piece square table scores. Perhaps
445 /// we should add scores from the pawn and material hash tables?
447 Value quick_evaluate(const Position &pos) {
452 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
454 Value mgv = pos.mg_value();
455 Value egv = pos.eg_value();
456 Phase ph = pos.game_phase();
457 Color stm = pos.side_to_move();
459 return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
463 /// init_eval() initializes various tables used by the evaluation function
465 void init_eval(int threads) {
467 assert(threads <= THREAD_MAX);
469 for (int i = 0; i < THREAD_MAX; i++)
474 delete MaterialTable[i];
476 MaterialTable[i] = NULL;
480 PawnTable[i] = new PawnInfoTable(PawnTableSize);
481 if (!MaterialTable[i])
482 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
487 /// quit_eval() releases heap-allocated memory at program termination
491 for (int i = 0; i < THREAD_MAX; i++)
494 delete MaterialTable[i];
496 MaterialTable[i] = NULL;
501 /// read_weights() reads evaluation weights from the corresponding UCI parameters
503 void read_weights(Color us) {
505 Color them = opposite_color(us);
507 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
508 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
509 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
510 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
511 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
512 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
513 WeightSpace = weight_option("Space", WeightSpaceInternal);
514 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
515 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
517 // If running in analysis mode, make sure we use symmetrical king safety. We do this
518 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
519 if (get_option_value_bool("UCI_AnalyseMode"))
521 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
522 WeightKingSafety[them] = WeightKingSafety[us];
530 // evaluate_mobility() computes mobility and attacks for every piece
532 template<PieceType Piece, Color Us, bool HasPopCnt>
533 int evaluate_mobility(const Position& pos, Bitboard b, EvalInfo& ei) {
535 const Color Them = (Us == WHITE ? BLACK : WHITE);
536 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
537 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
538 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
539 static const int lastIndex[] = { 0, 0, 8, 15, 15, 31 };
541 // Update attack info
542 ei.attackedBy[Us][Piece] |= b;
545 if (b & ei.kingZone[Us])
547 ei.kingAttackersCount[Us]++;
548 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
549 Bitboard bb = (b & ei.attackedBy[Them][KING]);
551 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
554 // Remove squares protected by enemy pawns or occupied by our pieces
555 b &= ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
557 // The squares occupied by enemy pieces (not defended by pawns) will be
558 // counted two times instead of one. The shift (almost) guarantees that
559 // intersection of the shifted value with b is zero so that after or-ing
560 // the count of 1s bits is increased by the number of affected squares.
561 b |= Us == WHITE ? ((b & pos.pieces_of_color(Them)) >> 1)
562 : ((b & pos.pieces_of_color(Them)) << 1);
565 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b)
566 : count_1s<HasPopCnt>(b));
568 if (mob > lastIndex[Piece])
569 mob = lastIndex[Piece];
571 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
572 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
577 // evaluate_outposts() evaluates bishop and knight outposts squares
579 template<PieceType Piece, Color Us>
580 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
582 const Color Them = (Us == WHITE ? BLACK : WHITE);
584 // Initial bonus based on square
585 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
586 : KnightOutpostBonus[relative_square(Us, s)]);
588 // Increase bonus if supported by pawn, especially if the opponent has
589 // no minor piece which can exchange the outpost piece
590 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
592 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
593 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
594 bonus += bonus + bonus / 2;
598 ei.mgValue += Sign[Us] * bonus;
599 ei.egValue += Sign[Us] * bonus;
603 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
605 template<PieceType Piece, Color Us, bool HasPopCnt>
606 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
613 const Color Them = (Us == WHITE ? BLACK : WHITE);
614 const Square* ptr = pos.piece_list_begin(Us, Piece);
616 while ((s = *ptr++) != SQ_NONE)
618 if (Piece == KNIGHT || Piece == QUEEN)
619 b = pos.attacks_from<Piece>(s);
620 else if (Piece == BISHOP)
621 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
622 else if (Piece == ROOK)
623 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
627 // Attacks and mobility
628 mob = evaluate_mobility<Piece, Us, HasPopCnt>(pos, b, ei);
630 // Bishop and knight outposts squares
631 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
632 evaluate_outposts<Piece, Us>(pos, ei, s);
634 // Special patterns: trapped bishops on a7/h7/a2/h2
635 // and trapped bishops on a1/h1/a8/h8 in Chess960.
638 if (bit_is_set(MaskA7H7[Us], s))
639 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
641 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
642 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
645 if (Piece == ROOK || Piece == QUEEN)
647 // Queen or rook on 7th rank
648 if ( relative_rank(Us, s) == RANK_7
649 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
651 ei.mgValue += Sign[Us] * (Piece == ROOK ? MidgameRookOn7thBonus : MidgameQueenOn7thBonus);
652 ei.egValue += Sign[Us] * (Piece == ROOK ? EndgameRookOn7thBonus : EndgameQueenOn7thBonus);
656 // Special extra evaluation for rooks
659 // Open and half-open files
661 if (ei.pi->file_is_half_open(Us, f))
663 if (ei.pi->file_is_half_open(Them, f))
665 ei.mgValue += Sign[Us] * RookOpenFileBonus;
666 ei.egValue += Sign[Us] * RookOpenFileBonus;
670 ei.mgValue += Sign[Us] * RookHalfOpenFileBonus;
671 ei.egValue += Sign[Us] * RookHalfOpenFileBonus;
675 // Penalize rooks which are trapped inside a king. Penalize more if
676 // king has lost right to castle.
677 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
680 ksq = pos.king_square(Us);
682 if ( square_file(ksq) >= FILE_E
683 && square_file(s) > square_file(ksq)
684 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
686 // Is there a half-open file between the king and the edge of the board?
687 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
688 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
689 : Sign[Us] * (TrappedRookPenalty - mob * 16);
691 else if ( square_file(ksq) <= FILE_D
692 && square_file(s) < square_file(ksq)
693 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
695 // Is there a half-open file between the king and the edge of the board?
696 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
697 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
698 : Sign[Us] * (TrappedRookPenalty - mob * 16);
705 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
706 // pieces of a given color.
708 template<Color Us, bool HasPopCnt>
709 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
711 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
712 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
713 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
714 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
716 // Sum up all attacked squares
717 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
718 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
719 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
723 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
725 template<Color Us, bool HasPopCnt>
726 void evaluate_king(const Position& pos, EvalInfo& ei) {
728 const Color Them = (Us == WHITE ? BLACK : WHITE);
729 const Square s = pos.king_square(Us);
733 if (relative_rank(Us, s) <= RANK_4)
735 shelter = ei.pi->get_king_shelter(pos, Us, s);
736 ei.mgValue += Sign[Us] * Value(shelter);
739 // King safety. This is quite complicated, and is almost certainly far
740 // from optimally tuned.
741 if ( pos.piece_count(Them, QUEEN) >= 1
742 && ei.kingAttackersCount[Them] >= 2
743 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
744 && ei.kingAdjacentZoneAttacksCount[Them])
746 // Is it the attackers turn to move?
747 bool sente = (Them == pos.side_to_move());
749 // Find the attacked squares around the king which has no defenders
750 // apart from the king itself
751 Bitboard undefended =
752 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
753 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
754 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
755 & ei.attacked_by(Us, KING);
757 Bitboard occ = pos.occupied_squares(), b, b2;
759 // Initialize the 'attackUnits' variable, which is used later on as an
760 // index to the SafetyTable[] array. The initial value is based on the
761 // number and types of the attacking pieces, the number of attacked and
762 // undefended squares around the king, the square of the king, and the
763 // quality of the pawn shelter.
765 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
766 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
767 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
769 // Analyse safe queen contact checks
770 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
773 Bitboard attackedByOthers =
774 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
775 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
777 b &= attackedByOthers;
780 // The bitboard b now contains the squares available for safe queen
782 int count = count_1s_max_15<HasPopCnt>(b);
783 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
785 // Is there a mate threat?
786 if (QueenContactMates && !pos.is_check())
788 Bitboard escapeSquares =
789 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
793 Square from, to = pop_1st_bit(&b);
794 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
796 // We have a mate, unless the queen is pinned or there
797 // is an X-ray attack through the queen.
798 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
800 from = pos.piece_list(Them, QUEEN, i);
801 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
802 && !bit_is_set(pos.pinned_pieces(Them), from)
803 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
804 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
806 ei.mateThreat[Them] = make_move(from, to);
814 // Analyse safe distance checks
815 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
817 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
820 b2 = b & ei.attacked_by(Them, QUEEN);
822 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
825 b2 = b & ei.attacked_by(Them, ROOK);
827 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
829 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
831 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
834 b2 = b & ei.attacked_by(Them, QUEEN);
836 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
839 b2 = b & ei.attacked_by(Them, BISHOP);
841 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
843 if (KnightCheckBonus > 0)
845 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
848 b2 = b & ei.attacked_by(Them, KNIGHT);
850 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
853 // Analyse discovered checks (only for non-pawns right now, consider
854 // adding pawns later).
855 if (DiscoveredCheckBonus)
857 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
859 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
862 // Has a mate threat been found? We don't do anything here if the
863 // side with the mating move is the side to move, because in that
864 // case the mating side will get a huge bonus at the end of the main
865 // evaluation function instead.
866 if (ei.mateThreat[Them] != MOVE_NONE)
867 attackUnits += MateThreatBonus;
869 // Ensure that attackUnits is between 0 and 99, in order to avoid array
870 // out of bounds errors:
874 if (attackUnits >= 100)
877 // Finally, extract the king safety score from the SafetyTable[] array.
878 // Add the score to the evaluation, and also to ei.futilityMargin. The
879 // reason for adding the king safety score to the futility margin is
880 // that the king safety scores can sometimes be very big, and that
881 // capturing a single attacking piece can therefore result in a score
882 // change far bigger than the value of the captured piece.
883 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
885 ei.mgValue -= Sign[Us] * v;
887 if (Us == pos.side_to_move())
888 ei.futilityMargin += v;
893 // evaluate_passed_pawns() evaluates the passed pawns of the given color
896 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
898 const Color Them = (Us == WHITE ? BLACK : WHITE);
901 Square ourKingSq = pos.king_square(Us);
902 Square theirKingSq = pos.king_square(Them);
903 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
907 Square s = pop_1st_bit(&b);
909 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
910 assert(pos.pawn_is_passed(Us, s));
912 int r = int(relative_rank(Us, s) - RANK_2);
913 int tr = Max(0, r * (r - 1));
915 // Base bonus based on rank
916 Value mbonus = Value(20 * tr);
917 Value ebonus = Value(10 + r * r * 10);
919 // Adjust bonus based on king proximity
922 Square blockSq = s + pawn_push(Us);
924 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
925 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
926 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
928 // If the pawn is free to advance, increase bonus
929 if (pos.square_is_empty(blockSq))
931 // There are no enemy pawns in the pawn's path
932 b2 = squares_in_front_of(Us, s);
934 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
936 // Squares attacked by us
937 b4 = b2 & ei.attacked_by(Us);
939 // Squares attacked or occupied by enemy pieces
940 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
942 // If there is an enemy rook or queen attacking the pawn from behind,
943 // add all X-ray attacks by the rook or queen.
944 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
945 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
948 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
949 if (b3 == EmptyBoardBB)
950 // No enemy attacks or pieces, huge bonus!
951 // Even bigger if we protect the pawn's path
952 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
954 // OK, there are enemy attacks or pieces (but not pawns). Are those
955 // squares which are attacked by the enemy also attacked by us ?
956 // If yes, big bonus (but smaller than when there are no enemy attacks),
957 // if no, somewhat smaller bonus.
958 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
960 // At last, add a small bonus when there are no *friendly* pieces
961 // in the pawn's path.
962 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
967 // If the pawn is supported by a friendly pawn, increase bonus
968 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
970 ebonus += Value(r * 20);
971 else if (pos.attacks_from<PAWN>(s, Them) & b2)
972 ebonus += Value(r * 12);
974 // If the other side has only a king, check whether the pawn is
976 if (pos.non_pawn_material(Them) == Value(0))
981 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
982 d = square_distance(s, qsq)
983 - square_distance(theirKingSq, qsq)
984 + (Us != pos.side_to_move());
988 int mtg = RANK_8 - relative_rank(Us, s);
989 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
992 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1000 // Rook pawns are a special case: They are sometimes worse, and
1001 // sometimes better than other passed pawns. It is difficult to find
1002 // good rules for determining whether they are good or bad. For now,
1003 // we try the following: Increase the value for rook pawns if the
1004 // other side has no pieces apart from a knight, and decrease the
1005 // value if the other side has a rook or queen.
1006 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1008 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1009 && pos.piece_count(Them, KNIGHT) <= 1)
1010 ebonus += ebonus / 4;
1011 else if (pos.pieces(ROOK, QUEEN, Them))
1012 ebonus -= ebonus / 4;
1015 // Add the scores for this pawn to the middle game and endgame eval.
1016 ei.mgValue += apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame);
1017 ei.egValue += apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame);
1023 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1025 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1027 int movesToGo[2] = {0, 0};
1028 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1030 // Evaluate pawns for each color
1031 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1032 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1034 // Neither side has an unstoppable passed pawn?
1035 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1038 // Does only one side have an unstoppable passed pawn?
1039 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1041 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1042 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide]));
1045 { // Both sides have unstoppable pawns! Try to find out who queens
1046 // first. We begin by transforming 'movesToGo' to the number of
1047 // plies until the pawn queens for both sides.
1048 movesToGo[WHITE] *= 2;
1049 movesToGo[BLACK] *= 2;
1050 movesToGo[pos.side_to_move()]--;
1052 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1053 Color loserSide = opposite_color(winnerSide);
1055 // If one side queens at least three plies before the other, that side wins
1056 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1057 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1059 // If one side queens one ply before the other and checks the king or attacks
1060 // the undefended opponent's queening square, that side wins. To avoid cases
1061 // where the opponent's king could move somewhere before first pawn queens we
1062 // consider only free paths to queen for both pawns.
1063 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1064 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1066 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1068 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1069 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1071 Bitboard b = pos.attacks_from<QUEEN>(winnerQSq);
1073 if ( (b & pos.pieces(KING, loserSide))
1074 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1075 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1081 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1082 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1085 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1087 assert(square_is_ok(s));
1088 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1090 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1091 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1093 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1094 && pos.see(s, b6) < 0
1095 && pos.see(s, b8) < 0)
1097 ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
1098 ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
1103 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1104 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1105 // black), and assigns a penalty if it is. This pattern can obviously
1106 // only occur in Chess960 games.
1108 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1110 Piece pawn = piece_of_color_and_type(us, PAWN);
1114 assert(square_is_ok(s));
1115 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1117 if (square_file(s) == FILE_A)
1119 b2 = relative_square(us, SQ_B2);
1120 b3 = relative_square(us, SQ_B3);
1121 c3 = relative_square(us, SQ_C3);
1125 b2 = relative_square(us, SQ_G2);
1126 b3 = relative_square(us, SQ_G3);
1127 c3 = relative_square(us, SQ_F3);
1130 if (pos.piece_on(b2) == pawn)
1134 if (!pos.square_is_empty(b3))
1135 penalty = 2*TrappedBishopA1H1Penalty;
1136 else if (pos.piece_on(c3) == pawn)
1137 penalty = TrappedBishopA1H1Penalty;
1139 penalty = TrappedBishopA1H1Penalty / 2;
1141 ei.mgValue -= Sign[us] * penalty;
1142 ei.egValue -= Sign[us] * penalty;
1147 // evaluate_space() computes the space evaluation for a given side. The
1148 // space evaluation is a simple bonus based on the number of safe squares
1149 // available for minor pieces on the central four files on ranks 2--4. Safe
1150 // squares one, two or three squares behind a friendly pawn are counted
1151 // twice. Finally, the space bonus is scaled by a weight taken from the
1152 // material hash table.
1153 template<Color Us, bool HasPopCnt>
1154 void evaluate_space(const Position& pos, EvalInfo& ei) {
1156 const Color Them = (Us == WHITE ? BLACK : WHITE);
1158 // Find the safe squares for our pieces inside the area defined by
1159 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1160 // pawn, or if it is undefended and attacked by an enemy piece.
1162 Bitboard safeSquares = SpaceMask[Us]
1163 & ~pos.pieces(PAWN, Us)
1164 & ~ei.attacked_by(Them, PAWN)
1165 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1167 // Find all squares which are at most three squares behind some friendly
1169 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1170 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1171 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1173 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1174 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1176 ei.mgValue += Sign[Us] * apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
1180 // apply_weight() applies an evaluation weight to a value
1182 inline Value apply_weight(Value v, int w) {
1183 return (v*w) / 0x100;
1187 // scale_by_game_phase() interpolates between a middle game and an endgame
1188 // score, based on game phase. It also scales the return value by a
1189 // ScaleFactor array.
1191 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
1193 assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
1194 assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
1195 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1197 ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
1199 Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
1200 return Value(int(result) & ~(GrainSize - 1));
1204 // weight_option() computes the value of an evaluation weight, by combining
1205 // an UCI-configurable weight with an internal weight.
1207 int weight_option(const std::string& opt, int internalWeight) {
1209 int uciWeight = get_option_value_int(opt);
1210 uciWeight = (uciWeight * 0x100) / 100;
1211 return (uciWeight * internalWeight) / 0x100;
1215 // init_safety() initizes the king safety evaluation, based on UCI
1216 // parameters. It is called from read_weights().
1218 void init_safety() {
1220 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1221 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1222 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1223 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1224 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1225 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1226 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1228 int maxSlope = get_option_value_int("King Safety Max Slope");
1229 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1230 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1231 double b = get_option_value_int("King Safety X Intercept");
1232 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1233 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1235 for (int i = 0; i < 100; i++)
1238 SafetyTable[i] = Value(0);
1240 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1242 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1245 for (int i = 0; i < 100; i++)
1247 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1248 for (int j = i + 1; j < 100; j++)
1249 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1251 if (SafetyTable[i] > Value(peak))
1252 SafetyTable[i] = Value(peak);