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);
312 assert(!pos.is_check());
314 memset(&ei, 0, sizeof(EvalInfo));
316 // Initialize by reading the incrementally updated scores included in the
317 // position object (material + piece square tables)
318 ei.mgValue = pos.mg_value();
319 ei.egValue = pos.eg_value();
321 // Probe the material hash table
322 ei.mi = MaterialTable[threadID]->get_material_info(pos);
323 ei.mgValue += ei.mi->material_value();
324 ei.egValue += ei.mi->material_value();
326 // If we have a specialized evaluation function for the current material
327 // configuration, call it and return
328 if (ei.mi->specialized_eval_exists())
329 return ei.mi->evaluate(pos);
331 // After get_material_info() call that modifies them
332 ScaleFactor factor[2];
333 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
334 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
336 // Probe the pawn hash table
337 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
338 ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
339 ei.egValue += apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame);
341 // Initialize king attack bitboards and king attack zones for both sides
342 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
343 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
344 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
345 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
347 // Initialize pawn attack bitboards for both sides
348 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
349 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
350 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
351 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
353 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
356 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
359 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
360 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
362 // Kings. Kings are evaluated after all other pieces for both sides,
363 // because we need complete attack information for all pieces when computing
364 // the king safety evaluation.
365 evaluate_king<WHITE, HasPopCnt>(pos, ei);
366 evaluate_king<BLACK, HasPopCnt>(pos, ei);
368 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
369 // because we need to know which side promotes first in positions where
370 // both sides have an unstoppable passed pawn. To be called after all attacks
371 // are computed, included king.
372 if (ei.pi->passed_pawns())
373 evaluate_passed_pawns(pos, ei);
375 Phase phase = pos.game_phase();
377 // Middle-game specific evaluation terms
378 if (phase > PHASE_ENDGAME)
380 // Pawn storms in positions with opposite castling.
381 if ( square_file(pos.king_square(WHITE)) >= FILE_E
382 && square_file(pos.king_square(BLACK)) <= FILE_D)
384 ei.mgValue += ei.pi->queenside_storm_value(WHITE)
385 - ei.pi->kingside_storm_value(BLACK);
387 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
388 && square_file(pos.king_square(BLACK)) >= FILE_E)
390 ei.mgValue += ei.pi->kingside_storm_value(WHITE)
391 - ei.pi->queenside_storm_value(BLACK);
393 // Evaluate space for both sides
394 if (ei.mi->space_weight() > 0)
396 evaluate_space<WHITE, HasPopCnt>(pos, ei);
397 evaluate_space<BLACK, HasPopCnt>(pos, ei);
402 ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
403 ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
405 // If we don't already have an unusual scale factor, check for opposite
406 // colored bishop endgames, and use a lower scale for those
407 if ( phase < PHASE_MIDGAME
408 && pos.opposite_colored_bishops()
409 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
410 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
414 // Only the two bishops ?
415 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
416 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
418 // Check for KBP vs KB with only a single pawn that is almost
419 // certainly a draw or at least two pawns.
420 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
421 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
424 // Endgame with opposite-colored bishops, but also other pieces. Still
425 // a bit drawish, but not as drawish as with only the two bishops.
426 sf = ScaleFactor(50);
428 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
430 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
434 // Interpolate between the middle game and the endgame score
435 Color stm = pos.side_to_move();
437 Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
439 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
444 /// quick_evaluate() does a very approximate evaluation of the current position.
445 /// It currently considers only material and piece square table scores. Perhaps
446 /// we should add scores from the pawn and material hash tables?
448 Value quick_evaluate(const Position &pos) {
453 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
455 Value mgv = pos.mg_value();
456 Value egv = pos.eg_value();
457 Phase ph = pos.game_phase();
458 Color stm = pos.side_to_move();
460 return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
464 /// init_eval() initializes various tables used by the evaluation function
466 void init_eval(int threads) {
468 assert(threads <= THREAD_MAX);
470 for (int i = 0; i < THREAD_MAX; i++)
475 delete MaterialTable[i];
477 MaterialTable[i] = NULL;
481 PawnTable[i] = new PawnInfoTable(PawnTableSize);
482 if (!MaterialTable[i])
483 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
488 /// quit_eval() releases heap-allocated memory at program termination
492 for (int i = 0; i < THREAD_MAX; i++)
495 delete MaterialTable[i];
497 MaterialTable[i] = NULL;
502 /// read_weights() reads evaluation weights from the corresponding UCI parameters
504 void read_weights(Color us) {
506 Color them = opposite_color(us);
508 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
509 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
510 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
511 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
512 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
513 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
514 WeightSpace = weight_option("Space", WeightSpaceInternal);
515 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
516 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
518 // If running in analysis mode, make sure we use symmetrical king safety. We do this
519 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
520 if (get_option_value_bool("UCI_AnalyseMode"))
522 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
523 WeightKingSafety[them] = WeightKingSafety[us];
531 // evaluate_mobility() computes mobility and attacks for every piece
533 template<PieceType Piece, Color Us, bool HasPopCnt>
534 int evaluate_mobility(const Position& pos, Bitboard b, Bitboard mob_area, EvalInfo& ei) {
536 const Color Them = (Us == WHITE ? BLACK : WHITE);
537 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
538 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
539 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
540 static const int lastIndex[] = { 0, 0, 8, 15, 15, 31 };
542 // Update attack info
543 ei.attackedBy[Us][Piece] |= b;
546 if (b & ei.kingZone[Us])
548 ei.kingAttackersCount[Us]++;
549 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
550 Bitboard bb = (b & ei.attackedBy[Them][KING]);
552 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
555 // The squares occupied by enemy pieces (not defended by pawns) will be
556 // counted two times instead of one. The shift (almost) guarantees that
557 // intersection of the shifted value with b is zero so that after or-ing
558 // the count of 1s bits is increased by the number of affected squares.
560 b |= Us == WHITE ? ((b & pos.pieces_of_color(Them)) >> 1)
561 : ((b & pos.pieces_of_color(Them)) << 1);
564 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b)
565 : count_1s<HasPopCnt>(b));
567 if (mob > lastIndex[Piece])
568 mob = lastIndex[Piece];
570 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
571 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
576 // evaluate_outposts() evaluates bishop and knight outposts squares
578 template<PieceType Piece, Color Us>
579 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
581 const Color Them = (Us == WHITE ? BLACK : WHITE);
583 // Initial bonus based on square
584 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
585 : KnightOutpostBonus[relative_square(Us, s)]);
587 // Increase bonus if supported by pawn, especially if the opponent has
588 // no minor piece which can exchange the outpost piece
589 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
591 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
592 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
593 bonus += bonus + bonus / 2;
597 ei.mgValue += Sign[Us] * bonus;
598 ei.egValue += Sign[Us] * bonus;
602 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
604 template<PieceType Piece, Color Us, bool HasPopCnt>
605 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
612 const Color Them = (Us == WHITE ? BLACK : WHITE);
613 const Square* ptr = pos.piece_list_begin(Us, Piece);
615 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
616 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
618 while ((s = *ptr++) != SQ_NONE)
620 if (Piece == KNIGHT || Piece == QUEEN)
621 b = pos.attacks_from<Piece>(s);
622 else if (Piece == BISHOP)
623 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
624 else if (Piece == ROOK)
625 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
629 // Attacks and mobility
630 mob = evaluate_mobility<Piece, Us, HasPopCnt>(pos, b, mob_area, ei);
632 // Bishop and knight outposts squares
633 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
634 evaluate_outposts<Piece, Us>(pos, ei, s);
636 // Special patterns: trapped bishops on a7/h7/a2/h2
637 // and trapped bishops on a1/h1/a8/h8 in Chess960.
640 if (bit_is_set(MaskA7H7[Us], s))
641 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
643 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
644 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
647 if (Piece == ROOK || Piece == QUEEN)
649 // Queen or rook on 7th rank
650 if ( relative_rank(Us, s) == RANK_7
651 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
653 ei.mgValue += Sign[Us] * (Piece == ROOK ? MidgameRookOn7thBonus : MidgameQueenOn7thBonus);
654 ei.egValue += Sign[Us] * (Piece == ROOK ? EndgameRookOn7thBonus : EndgameQueenOn7thBonus);
658 // Special extra evaluation for rooks
661 // Open and half-open files
663 if (ei.pi->file_is_half_open(Us, f))
665 if (ei.pi->file_is_half_open(Them, f))
667 ei.mgValue += Sign[Us] * RookOpenFileBonus;
668 ei.egValue += Sign[Us] * RookOpenFileBonus;
672 ei.mgValue += Sign[Us] * RookHalfOpenFileBonus;
673 ei.egValue += Sign[Us] * RookHalfOpenFileBonus;
677 // Penalize rooks which are trapped inside a king. Penalize more if
678 // king has lost right to castle.
679 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
682 ksq = pos.king_square(Us);
684 if ( square_file(ksq) >= FILE_E
685 && square_file(s) > square_file(ksq)
686 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
688 // Is there a half-open file between the king and the edge of the board?
689 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
690 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
691 : Sign[Us] * (TrappedRookPenalty - mob * 16);
693 else if ( square_file(ksq) <= FILE_D
694 && square_file(s) < square_file(ksq)
695 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
697 // Is there a half-open file between the king and the edge of the board?
698 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
699 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
700 : Sign[Us] * (TrappedRookPenalty - mob * 16);
707 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
708 // pieces of a given color.
710 template<Color Us, bool HasPopCnt>
711 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
713 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
714 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
715 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
716 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
718 // Sum up all attacked squares
719 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
720 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
721 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
725 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
727 template<Color Us, bool HasPopCnt>
728 void evaluate_king(const Position& pos, EvalInfo& ei) {
730 const Color Them = (Us == WHITE ? BLACK : WHITE);
731 const Square s = pos.king_square(Us);
735 if (relative_rank(Us, s) <= RANK_4)
737 shelter = ei.pi->get_king_shelter(pos, Us, s);
738 ei.mgValue += Sign[Us] * Value(shelter);
741 // King safety. This is quite complicated, and is almost certainly far
742 // from optimally tuned.
743 if ( pos.piece_count(Them, QUEEN) >= 1
744 && ei.kingAttackersCount[Them] >= 2
745 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
746 && ei.kingAdjacentZoneAttacksCount[Them])
748 // Is it the attackers turn to move?
749 bool sente = (Them == pos.side_to_move());
751 // Find the attacked squares around the king which has no defenders
752 // apart from the king itself
753 Bitboard undefended =
754 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
755 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
756 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
757 & ei.attacked_by(Us, KING);
759 Bitboard occ = pos.occupied_squares(), b, b2;
761 // Initialize the 'attackUnits' variable, which is used later on as an
762 // index to the SafetyTable[] array. The initial value is based on the
763 // number and types of the attacking pieces, the number of attacked and
764 // undefended squares around the king, the square of the king, and the
765 // quality of the pawn shelter.
767 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
768 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
769 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
771 // Analyse safe queen contact checks
772 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
775 Bitboard attackedByOthers =
776 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
777 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
779 b &= attackedByOthers;
782 // The bitboard b now contains the squares available for safe queen
784 int count = count_1s_max_15<HasPopCnt>(b);
785 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
787 // Is there a mate threat?
788 if (QueenContactMates && !pos.is_check())
790 Bitboard escapeSquares =
791 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
795 Square from, to = pop_1st_bit(&b);
796 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
798 // We have a mate, unless the queen is pinned or there
799 // is an X-ray attack through the queen.
800 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
802 from = pos.piece_list(Them, QUEEN, i);
803 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
804 && !bit_is_set(pos.pinned_pieces(Them), from)
805 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
806 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
808 ei.mateThreat[Them] = make_move(from, to);
816 // Analyse safe distance checks
817 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
819 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
822 b2 = b & ei.attacked_by(Them, QUEEN);
824 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
827 b2 = b & ei.attacked_by(Them, ROOK);
829 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
831 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
833 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
836 b2 = b & ei.attacked_by(Them, QUEEN);
838 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
841 b2 = b & ei.attacked_by(Them, BISHOP);
843 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
845 if (KnightCheckBonus > 0)
847 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
850 b2 = b & ei.attacked_by(Them, KNIGHT);
852 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
855 // Analyse discovered checks (only for non-pawns right now, consider
856 // adding pawns later).
857 if (DiscoveredCheckBonus)
859 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
861 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
864 // Has a mate threat been found? We don't do anything here if the
865 // side with the mating move is the side to move, because in that
866 // case the mating side will get a huge bonus at the end of the main
867 // evaluation function instead.
868 if (ei.mateThreat[Them] != MOVE_NONE)
869 attackUnits += MateThreatBonus;
871 // Ensure that attackUnits is between 0 and 99, in order to avoid array
872 // out of bounds errors:
876 if (attackUnits >= 100)
879 // Finally, extract the king safety score from the SafetyTable[] array.
880 // Add the score to the evaluation, and also to ei.futilityMargin. The
881 // reason for adding the king safety score to the futility margin is
882 // that the king safety scores can sometimes be very big, and that
883 // capturing a single attacking piece can therefore result in a score
884 // change far bigger than the value of the captured piece.
885 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
887 ei.mgValue -= Sign[Us] * v;
889 if (Us == pos.side_to_move())
890 ei.futilityMargin += v;
895 // evaluate_passed_pawns() evaluates the passed pawns of the given color
898 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
900 const Color Them = (Us == WHITE ? BLACK : WHITE);
903 Square ourKingSq = pos.king_square(Us);
904 Square theirKingSq = pos.king_square(Them);
905 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
909 Square s = pop_1st_bit(&b);
911 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
912 assert(pos.pawn_is_passed(Us, s));
914 int r = int(relative_rank(Us, s) - RANK_2);
915 int tr = Max(0, r * (r - 1));
917 // Base bonus based on rank
918 Value mbonus = Value(20 * tr);
919 Value ebonus = Value(10 + r * r * 10);
921 // Adjust bonus based on king proximity
924 Square blockSq = s + pawn_push(Us);
926 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
927 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
928 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
930 // If the pawn is free to advance, increase bonus
931 if (pos.square_is_empty(blockSq))
933 // There are no enemy pawns in the pawn's path
934 b2 = squares_in_front_of(Us, s);
936 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
938 // Squares attacked by us
939 b4 = b2 & ei.attacked_by(Us);
941 // Squares attacked or occupied by enemy pieces
942 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
944 // If there is an enemy rook or queen attacking the pawn from behind,
945 // add all X-ray attacks by the rook or queen.
946 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
947 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
950 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
951 if (b3 == EmptyBoardBB)
952 // No enemy attacks or pieces, huge bonus!
953 // Even bigger if we protect the pawn's path
954 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
956 // OK, there are enemy attacks or pieces (but not pawns). Are those
957 // squares which are attacked by the enemy also attacked by us ?
958 // If yes, big bonus (but smaller than when there are no enemy attacks),
959 // if no, somewhat smaller bonus.
960 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
962 // At last, add a small bonus when there are no *friendly* pieces
963 // in the pawn's path.
964 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
969 // If the pawn is supported by a friendly pawn, increase bonus
970 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
972 ebonus += Value(r * 20);
973 else if (pos.attacks_from<PAWN>(s, Them) & b2)
974 ebonus += Value(r * 12);
976 // If the other side has only a king, check whether the pawn is
978 if (pos.non_pawn_material(Them) == Value(0))
983 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
984 d = square_distance(s, qsq)
985 - square_distance(theirKingSq, qsq)
986 + (Us != pos.side_to_move());
990 int mtg = RANK_8 - relative_rank(Us, s);
991 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
994 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1002 // Rook pawns are a special case: They are sometimes worse, and
1003 // sometimes better than other passed pawns. It is difficult to find
1004 // good rules for determining whether they are good or bad. For now,
1005 // we try the following: Increase the value for rook pawns if the
1006 // other side has no pieces apart from a knight, and decrease the
1007 // value if the other side has a rook or queen.
1008 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1010 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1011 && pos.piece_count(Them, KNIGHT) <= 1)
1012 ebonus += ebonus / 4;
1013 else if (pos.pieces(ROOK, QUEEN, Them))
1014 ebonus -= ebonus / 4;
1017 // Add the scores for this pawn to the middle game and endgame eval.
1018 ei.mgValue += apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame);
1019 ei.egValue += apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame);
1025 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1027 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1029 int movesToGo[2] = {0, 0};
1030 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1032 // Evaluate pawns for each color
1033 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1034 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1036 // Neither side has an unstoppable passed pawn?
1037 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1040 // Does only one side have an unstoppable passed pawn?
1041 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1043 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1044 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide]));
1047 { // Both sides have unstoppable pawns! Try to find out who queens
1048 // first. We begin by transforming 'movesToGo' to the number of
1049 // plies until the pawn queens for both sides.
1050 movesToGo[WHITE] *= 2;
1051 movesToGo[BLACK] *= 2;
1052 movesToGo[pos.side_to_move()]--;
1054 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1055 Color loserSide = opposite_color(winnerSide);
1057 // If one side queens at least three plies before the other, that side wins
1058 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1059 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1061 // If one side queens one ply before the other and checks the king or attacks
1062 // the undefended opponent's queening square, that side wins. To avoid cases
1063 // where the opponent's king could move somewhere before first pawn queens we
1064 // consider only free paths to queen for both pawns.
1065 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1066 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1068 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1070 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1071 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1073 Bitboard b = pos.occupied_squares();
1074 clear_bit(&b, pawnToGo[winnerSide]);
1075 clear_bit(&b, pawnToGo[loserSide]);
1076 b = queen_attacks_bb(winnerQSq, b);
1078 if ( (b & pos.pieces(KING, loserSide))
1079 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1080 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1086 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1087 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1090 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1092 assert(square_is_ok(s));
1093 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1095 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1096 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1098 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1099 && pos.see(s, b6) < 0
1100 && pos.see(s, b8) < 0)
1102 ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
1103 ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
1108 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1109 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1110 // black), and assigns a penalty if it is. This pattern can obviously
1111 // only occur in Chess960 games.
1113 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1115 Piece pawn = piece_of_color_and_type(us, PAWN);
1119 assert(square_is_ok(s));
1120 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1122 if (square_file(s) == FILE_A)
1124 b2 = relative_square(us, SQ_B2);
1125 b3 = relative_square(us, SQ_B3);
1126 c3 = relative_square(us, SQ_C3);
1130 b2 = relative_square(us, SQ_G2);
1131 b3 = relative_square(us, SQ_G3);
1132 c3 = relative_square(us, SQ_F3);
1135 if (pos.piece_on(b2) == pawn)
1139 if (!pos.square_is_empty(b3))
1140 penalty = 2*TrappedBishopA1H1Penalty;
1141 else if (pos.piece_on(c3) == pawn)
1142 penalty = TrappedBishopA1H1Penalty;
1144 penalty = TrappedBishopA1H1Penalty / 2;
1146 ei.mgValue -= Sign[us] * penalty;
1147 ei.egValue -= Sign[us] * penalty;
1152 // evaluate_space() computes the space evaluation for a given side. The
1153 // space evaluation is a simple bonus based on the number of safe squares
1154 // available for minor pieces on the central four files on ranks 2--4. Safe
1155 // squares one, two or three squares behind a friendly pawn are counted
1156 // twice. Finally, the space bonus is scaled by a weight taken from the
1157 // material hash table.
1158 template<Color Us, bool HasPopCnt>
1159 void evaluate_space(const Position& pos, EvalInfo& ei) {
1161 const Color Them = (Us == WHITE ? BLACK : WHITE);
1163 // Find the safe squares for our pieces inside the area defined by
1164 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1165 // pawn, or if it is undefended and attacked by an enemy piece.
1167 Bitboard safeSquares = SpaceMask[Us]
1168 & ~pos.pieces(PAWN, Us)
1169 & ~ei.attacked_by(Them, PAWN)
1170 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1172 // Find all squares which are at most three squares behind some friendly
1174 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1175 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1176 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1178 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1179 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1181 ei.mgValue += Sign[Us] * apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
1185 // apply_weight() applies an evaluation weight to a value
1187 inline Value apply_weight(Value v, int w) {
1188 return (v*w) / 0x100;
1192 // scale_by_game_phase() interpolates between a middle game and an endgame
1193 // score, based on game phase. It also scales the return value by a
1194 // ScaleFactor array.
1196 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
1198 assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
1199 assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
1200 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1202 ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
1204 Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
1205 return Value(int(result) & ~(GrainSize - 1));
1209 // weight_option() computes the value of an evaluation weight, by combining
1210 // an UCI-configurable weight with an internal weight.
1212 int weight_option(const std::string& opt, int internalWeight) {
1214 int uciWeight = get_option_value_int(opt);
1215 uciWeight = (uciWeight * 0x100) / 100;
1216 return (uciWeight * internalWeight) / 0x100;
1220 // init_safety() initizes the king safety evaluation, based on UCI
1221 // parameters. It is called from read_weights().
1223 void init_safety() {
1225 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1226 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1227 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1228 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1229 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1230 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1231 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1233 int maxSlope = get_option_value_int("King Safety Max Slope");
1234 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1235 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1236 double b = get_option_value_int("King Safety X Intercept");
1237 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1238 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1240 for (int i = 0; i < 100; i++)
1243 SafetyTable[i] = Value(0);
1245 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1247 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1250 for (int i = 0; i < 100; i++)
1252 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1253 for (int j = i + 1; j < 100; j++)
1254 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1256 if (SafetyTable[i] > Value(peak))
1257 SafetyTable[i] = Value(peak);