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 // ThreatBonus[][] contains bonus according to which piece type
245 // attacks which one.
246 const Value MidgameThreatBonus[8][8] = {
247 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
248 { V(0),V(18), V(0),V(37), V(55), V(55), V(0), V(0) }, // KNIGHT attacks
249 { V(0),V(18),V(37), V(0), V(55), V(55), V(0), V(0) }, // BISHOP attacks
250 { V(0), V(9),V(27),V(27), V(0), V(37), V(0), V(0) }, // ROOK attacks
251 { V(0),V(27),V(27),V(27), V(27), V(0), V(0), V(0) }, // QUEEN attacks
252 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
253 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
254 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) } // not used
257 const Value EndgameThreatBonus[8][8] = {
258 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
259 { V(0),V(37), V(0),V(47), V(97), V(97), V(0), V(0) }, // KNIGHT attacks
260 { V(0),V(37),V(47), V(0), V(97), V(97), V(0), V(0) }, // BISHOP attacks
261 { V(0),V(27),V(47),V(47), V(0), V(47), V(0), V(0) }, // ROOK attacks
262 { V(0),V(37),V(37),V(37), V(37), V(0), V(0), V(0) }, // QUEEN attacks
263 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
264 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
265 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) } // not used
268 // ThreatedByPawnPenalty[] contains a penalty according to which piece
269 // type is attacked by an enemy pawn.
270 const Value MidgameThreatedByPawnPenalty[8] = {
271 V(0), V(0), V(56), V(56), V(76), V(86), V(0), V(0)
274 const Value EndgameThreatedByPawnPenalty[8] = {
275 V(0), V(0), V(70), V(70), V(99), V(118), V(0), V(0)
278 // InitKingDanger[] contains bonuses based on the position of the defending
280 const int InitKingDanger[64] = {
281 2, 0, 2, 5, 5, 2, 0, 2,
282 2, 2, 4, 8, 8, 4, 2, 2,
283 7, 10, 12, 12, 12, 12, 10, 7,
284 15, 15, 15, 15, 15, 15, 15, 15,
285 15, 15, 15, 15, 15, 15, 15, 15,
286 15, 15, 15, 15, 15, 15, 15, 15,
287 15, 15, 15, 15, 15, 15, 15, 15,
288 15, 15, 15, 15, 15, 15, 15, 15
291 // SafetyTable[] contains the actual king safety scores. It is initialized
293 Value SafetyTable[100];
295 // Pawn and material hash tables, indexed by the current thread id
296 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
297 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
299 // Sizes of pawn and material hash tables
300 const int PawnTableSize = 16384;
301 const int MaterialTableSize = 1024;
303 // Function prototypes
304 template<bool HasPopCnt>
305 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
307 template<Color Us, bool HasPopCnt>
308 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
310 template<Color Us, bool HasPopCnt>
311 void evaluate_king(const Position& pos, EvalInfo& ei);
314 void evaluate_threats(const Position& pos, EvalInfo& ei);
316 template<Color Us, bool HasPopCnt>
317 void evaluate_space(const Position& pos, EvalInfo& ei);
319 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
320 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
321 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
322 inline Value apply_weight(Value v, int w);
323 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
324 int weight_option(const std::string& opt, int weight);
333 /// evaluate() is the main evaluation function. It always computes two
334 /// values, an endgame score and a middle game score, and interpolates
335 /// between them based on the remaining material.
336 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
338 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
339 : do_evaluate<false>(pos, ei, threadID);
344 template<bool HasPopCnt>
345 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
348 assert(threadID >= 0 && threadID < THREAD_MAX);
349 assert(!pos.is_check());
351 memset(&ei, 0, sizeof(EvalInfo));
353 // Initialize by reading the incrementally updated scores included in the
354 // position object (material + piece square tables)
355 ei.mgValue = pos.mg_value();
356 ei.egValue = pos.eg_value();
358 // Probe the material hash table
359 ei.mi = MaterialTable[threadID]->get_material_info(pos);
360 ei.mgValue += ei.mi->material_value();
361 ei.egValue += ei.mi->material_value();
363 // If we have a specialized evaluation function for the current material
364 // configuration, call it and return
365 if (ei.mi->specialized_eval_exists())
366 return ei.mi->evaluate(pos);
368 // After get_material_info() call that modifies them
369 ScaleFactor factor[2];
370 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
371 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
373 // Probe the pawn hash table
374 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
375 ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
376 ei.egValue += apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame);
378 // Initialize king attack bitboards and king attack zones for both sides
379 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
380 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
381 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
382 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
384 // Initialize pawn attack bitboards for both sides
385 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
386 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
387 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
388 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
390 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
393 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
396 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
397 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
399 // Kings. Kings are evaluated after all other pieces for both sides,
400 // because we need complete attack information for all pieces when computing
401 // the king safety evaluation.
402 evaluate_king<WHITE, HasPopCnt>(pos, ei);
403 evaluate_king<BLACK, HasPopCnt>(pos, ei);
405 // Evaluate tactical threats, we need full attack info
406 evaluate_threats<WHITE>(pos, ei);
407 evaluate_threats<BLACK>(pos, ei);
409 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
410 // because we need to know which side promotes first in positions where
411 // both sides have an unstoppable passed pawn. To be called after all attacks
412 // are computed, included king.
413 if (ei.pi->passed_pawns())
414 evaluate_passed_pawns(pos, ei);
416 Phase phase = pos.game_phase();
418 // Middle-game specific evaluation terms
419 if (phase > PHASE_ENDGAME)
421 // Pawn storms in positions with opposite castling.
422 if ( square_file(pos.king_square(WHITE)) >= FILE_E
423 && square_file(pos.king_square(BLACK)) <= FILE_D)
425 ei.mgValue += ei.pi->queenside_storm_value(WHITE)
426 - ei.pi->kingside_storm_value(BLACK);
428 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
429 && square_file(pos.king_square(BLACK)) >= FILE_E)
431 ei.mgValue += ei.pi->kingside_storm_value(WHITE)
432 - ei.pi->queenside_storm_value(BLACK);
434 // Evaluate space for both sides
435 if (ei.mi->space_weight() > 0)
437 evaluate_space<WHITE, HasPopCnt>(pos, ei);
438 evaluate_space<BLACK, HasPopCnt>(pos, ei);
443 ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
444 ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
446 // If we don't already have an unusual scale factor, check for opposite
447 // colored bishop endgames, and use a lower scale for those
448 if ( phase < PHASE_MIDGAME
449 && pos.opposite_colored_bishops()
450 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
451 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
455 // Only the two bishops ?
456 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
457 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
459 // Check for KBP vs KB with only a single pawn that is almost
460 // certainly a draw or at least two pawns.
461 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
462 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
465 // Endgame with opposite-colored bishops, but also other pieces. Still
466 // a bit drawish, but not as drawish as with only the two bishops.
467 sf = ScaleFactor(50);
469 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
471 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
475 // Interpolate between the middle game and the endgame score
476 Color stm = pos.side_to_move();
478 Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
480 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
485 /// quick_evaluate() does a very approximate evaluation of the current position.
486 /// It currently considers only material and piece square table scores. Perhaps
487 /// we should add scores from the pawn and material hash tables?
489 Value quick_evaluate(const Position &pos) {
494 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
496 Value mgv = pos.mg_value();
497 Value egv = pos.eg_value();
498 Phase ph = pos.game_phase();
499 Color stm = pos.side_to_move();
501 return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
505 /// init_eval() initializes various tables used by the evaluation function
507 void init_eval(int threads) {
509 assert(threads <= THREAD_MAX);
511 for (int i = 0; i < THREAD_MAX; i++)
516 delete MaterialTable[i];
518 MaterialTable[i] = NULL;
522 PawnTable[i] = new PawnInfoTable(PawnTableSize);
523 if (!MaterialTable[i])
524 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
529 /// quit_eval() releases heap-allocated memory at program termination
533 for (int i = 0; i < THREAD_MAX; i++)
536 delete MaterialTable[i];
538 MaterialTable[i] = NULL;
543 /// read_weights() reads evaluation weights from the corresponding UCI parameters
545 void read_weights(Color us) {
547 Color them = opposite_color(us);
549 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
550 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
551 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
552 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
553 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
554 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
555 WeightSpace = weight_option("Space", WeightSpaceInternal);
556 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
557 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
559 // If running in analysis mode, make sure we use symmetrical king safety. We do this
560 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
561 if (get_option_value_bool("UCI_AnalyseMode"))
563 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
564 WeightKingSafety[them] = WeightKingSafety[us];
572 // evaluate_mobility() computes mobility and attacks for every piece
574 template<PieceType Piece, Color Us, bool HasPopCnt>
575 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
577 const Color Them = (Us == WHITE ? BLACK : WHITE);
578 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
579 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
580 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
582 // Update attack info
583 ei.attackedBy[Us][Piece] |= b;
586 if (b & ei.kingZone[Us])
588 ei.kingAttackersCount[Us]++;
589 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
590 Bitboard bb = (b & ei.attackedBy[Them][KING]);
592 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
596 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
597 : count_1s<HasPopCnt>(b & mob_area));
599 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
600 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
605 // evaluate_outposts() evaluates bishop and knight outposts squares
607 template<PieceType Piece, Color Us>
608 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
610 const Color Them = (Us == WHITE ? BLACK : WHITE);
612 // Initial bonus based on square
613 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
614 : KnightOutpostBonus[relative_square(Us, s)]);
616 // Increase bonus if supported by pawn, especially if the opponent has
617 // no minor piece which can exchange the outpost piece
618 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
620 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
621 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
622 bonus += bonus + bonus / 2;
626 ei.mgValue += Sign[Us] * bonus;
627 ei.egValue += Sign[Us] * bonus;
631 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
633 template<PieceType Piece, Color Us, bool HasPopCnt>
634 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
641 const Color Them = (Us == WHITE ? BLACK : WHITE);
642 const Square* ptr = pos.piece_list_begin(Us, Piece);
644 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
645 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
647 while ((s = *ptr++) != SQ_NONE)
649 if (Piece == KNIGHT || Piece == QUEEN)
650 b = pos.attacks_from<Piece>(s);
651 else if (Piece == BISHOP)
652 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
653 else if (Piece == ROOK)
654 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
658 // Attacks and mobility
659 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
661 // Decrease score if we are attacked by an enemy pawn. Remaining part
662 // of threat evaluation must be done later when we have full attack info.
663 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
665 ei.mgValue -= Sign[Us] * MidgameThreatedByPawnPenalty[Piece];
666 ei.egValue -= Sign[Us] * EndgameThreatedByPawnPenalty[Piece];
669 // Bishop and knight outposts squares
670 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
671 evaluate_outposts<Piece, Us>(pos, ei, s);
673 // Special patterns: trapped bishops on a7/h7/a2/h2
674 // and trapped bishops on a1/h1/a8/h8 in Chess960.
677 if (bit_is_set(MaskA7H7[Us], s))
678 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
680 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
681 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
684 if (Piece == ROOK || Piece == QUEEN)
686 // Queen or rook on 7th rank
687 if ( relative_rank(Us, s) == RANK_7
688 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
690 ei.mgValue += Sign[Us] * (Piece == ROOK ? MidgameRookOn7thBonus : MidgameQueenOn7thBonus);
691 ei.egValue += Sign[Us] * (Piece == ROOK ? EndgameRookOn7thBonus : EndgameQueenOn7thBonus);
695 // Special extra evaluation for rooks
698 // Open and half-open files
700 if (ei.pi->file_is_half_open(Us, f))
702 if (ei.pi->file_is_half_open(Them, f))
704 ei.mgValue += Sign[Us] * RookOpenFileBonus;
705 ei.egValue += Sign[Us] * RookOpenFileBonus;
709 ei.mgValue += Sign[Us] * RookHalfOpenFileBonus;
710 ei.egValue += Sign[Us] * RookHalfOpenFileBonus;
714 // Penalize rooks which are trapped inside a king. Penalize more if
715 // king has lost right to castle.
716 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
719 ksq = pos.king_square(Us);
721 if ( square_file(ksq) >= FILE_E
722 && square_file(s) > square_file(ksq)
723 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
725 // Is there a half-open file between the king and the edge of the board?
726 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
727 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
728 : Sign[Us] * (TrappedRookPenalty - mob * 16);
730 else if ( square_file(ksq) <= FILE_D
731 && square_file(s) < square_file(ksq)
732 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
734 // Is there a half-open file between the king and the edge of the board?
735 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
736 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
737 : Sign[Us] * (TrappedRookPenalty - mob * 16);
744 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
745 // and the type of attacked one.
748 void evaluate_threats(const Position& pos, EvalInfo& ei) {
750 const Color Them = (Us == WHITE ? BLACK : WHITE);
753 Value mgBonus = Value(0);
754 Value egBonus = Value(0);
756 // Enemy pieces not defended by a pawn and under our attack
757 Bitboard weakEnemies = pos.pieces_of_color(Them)
758 & ~ei.attackedBy[Them][PAWN]
759 & ei.attackedBy[Us][0];
763 // Add bonus according to type of attacked enemy pieces and to the
764 // type of attacking piece, from knights to queens. Kings are not
765 // considered because are already special handled in king evaluation.
766 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
768 b = ei.attackedBy[Us][pt1] & weakEnemies;
770 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
771 if (b & pos.pieces(pt2))
773 mgBonus += MidgameThreatBonus[pt1][pt2];
774 egBonus += EndgameThreatBonus[pt1][pt2];
777 ei.mgValue += Sign[Us] * mgBonus;
778 ei.egValue += Sign[Us] * egBonus;
782 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
783 // pieces of a given color.
785 template<Color Us, bool HasPopCnt>
786 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
788 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
789 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
790 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
791 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
793 // Sum up all attacked squares
794 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
795 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
796 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
800 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
802 template<Color Us, bool HasPopCnt>
803 void evaluate_king(const Position& pos, EvalInfo& ei) {
805 const Color Them = (Us == WHITE ? BLACK : WHITE);
806 const Square s = pos.king_square(Us);
810 if (relative_rank(Us, s) <= RANK_4)
812 shelter = ei.pi->get_king_shelter(pos, Us, s);
813 ei.mgValue += Sign[Us] * Value(shelter);
816 // King safety. This is quite complicated, and is almost certainly far
817 // from optimally tuned.
818 if ( pos.piece_count(Them, QUEEN) >= 1
819 && ei.kingAttackersCount[Them] >= 2
820 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
821 && ei.kingAdjacentZoneAttacksCount[Them])
823 // Is it the attackers turn to move?
824 bool sente = (Them == pos.side_to_move());
826 // Find the attacked squares around the king which has no defenders
827 // apart from the king itself
828 Bitboard undefended =
829 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
830 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
831 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
832 & ei.attacked_by(Us, KING);
834 Bitboard occ = pos.occupied_squares(), b, b2;
836 // Initialize the 'attackUnits' variable, which is used later on as an
837 // index to the SafetyTable[] array. The initial value is based on the
838 // number and types of the attacking pieces, the number of attacked and
839 // undefended squares around the king, the square of the king, and the
840 // quality of the pawn shelter.
842 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
843 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
844 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
846 // Analyse safe queen contact checks
847 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
850 Bitboard attackedByOthers =
851 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
852 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
854 b &= attackedByOthers;
857 // The bitboard b now contains the squares available for safe queen
859 int count = count_1s_max_15<HasPopCnt>(b);
860 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
862 // Is there a mate threat?
863 if (QueenContactMates && !pos.is_check())
865 Bitboard escapeSquares =
866 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
870 Square from, to = pop_1st_bit(&b);
871 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
873 // We have a mate, unless the queen is pinned or there
874 // is an X-ray attack through the queen.
875 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
877 from = pos.piece_list(Them, QUEEN, i);
878 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
879 && !bit_is_set(pos.pinned_pieces(Them), from)
880 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
881 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
883 ei.mateThreat[Them] = make_move(from, to);
891 // Analyse safe distance checks
892 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
894 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
897 b2 = b & ei.attacked_by(Them, QUEEN);
899 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
902 b2 = b & ei.attacked_by(Them, ROOK);
904 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
906 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
908 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
911 b2 = b & ei.attacked_by(Them, QUEEN);
913 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
916 b2 = b & ei.attacked_by(Them, BISHOP);
918 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
920 if (KnightCheckBonus > 0)
922 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
925 b2 = b & ei.attacked_by(Them, KNIGHT);
927 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
930 // Analyse discovered checks (only for non-pawns right now, consider
931 // adding pawns later).
932 if (DiscoveredCheckBonus)
934 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
936 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
939 // Has a mate threat been found? We don't do anything here if the
940 // side with the mating move is the side to move, because in that
941 // case the mating side will get a huge bonus at the end of the main
942 // evaluation function instead.
943 if (ei.mateThreat[Them] != MOVE_NONE)
944 attackUnits += MateThreatBonus;
946 // Ensure that attackUnits is between 0 and 99, in order to avoid array
947 // out of bounds errors:
951 if (attackUnits >= 100)
954 // Finally, extract the king safety score from the SafetyTable[] array.
955 // Add the score to the evaluation, and also to ei.futilityMargin. The
956 // reason for adding the king safety score to the futility margin is
957 // that the king safety scores can sometimes be very big, and that
958 // capturing a single attacking piece can therefore result in a score
959 // change far bigger than the value of the captured piece.
960 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
962 ei.mgValue -= Sign[Us] * v;
964 if (Us == pos.side_to_move())
965 ei.futilityMargin += v;
970 // evaluate_passed_pawns() evaluates the passed pawns of the given color
973 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
975 const Color Them = (Us == WHITE ? BLACK : WHITE);
978 Square ourKingSq = pos.king_square(Us);
979 Square theirKingSq = pos.king_square(Them);
980 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
984 Square s = pop_1st_bit(&b);
986 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
987 assert(pos.pawn_is_passed(Us, s));
989 int r = int(relative_rank(Us, s) - RANK_2);
990 int tr = Max(0, r * (r - 1));
992 // Base bonus based on rank
993 Value mbonus = Value(20 * tr);
994 Value ebonus = Value(10 + r * r * 10);
996 // Adjust bonus based on king proximity
999 Square blockSq = s + pawn_push(Us);
1001 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
1002 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
1003 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
1005 // If the pawn is free to advance, increase bonus
1006 if (pos.square_is_empty(blockSq))
1008 // There are no enemy pawns in the pawn's path
1009 b2 = squares_in_front_of(Us, s);
1011 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
1013 // Squares attacked by us
1014 b4 = b2 & ei.attacked_by(Us);
1016 // Squares attacked or occupied by enemy pieces
1017 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
1019 // If there is an enemy rook or queen attacking the pawn from behind,
1020 // add all X-ray attacks by the rook or queen.
1021 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
1022 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
1025 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
1026 if (b3 == EmptyBoardBB)
1027 // No enemy attacks or pieces, huge bonus!
1028 // Even bigger if we protect the pawn's path
1029 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
1031 // OK, there are enemy attacks or pieces (but not pawns). Are those
1032 // squares which are attacked by the enemy also attacked by us ?
1033 // If yes, big bonus (but smaller than when there are no enemy attacks),
1034 // if no, somewhat smaller bonus.
1035 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
1037 // At last, add a small bonus when there are no *friendly* pieces
1038 // in the pawn's path.
1039 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
1040 ebonus += Value(tr);
1044 // If the pawn is supported by a friendly pawn, increase bonus
1045 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
1046 if (b2 & rank_bb(s))
1047 ebonus += Value(r * 20);
1048 else if (pos.attacks_from<PAWN>(s, Them) & b2)
1049 ebonus += Value(r * 12);
1051 // If the other side has only a king, check whether the pawn is
1053 if (pos.non_pawn_material(Them) == Value(0))
1058 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1059 d = square_distance(s, qsq)
1060 - square_distance(theirKingSq, qsq)
1061 + (Us != pos.side_to_move());
1065 int mtg = RANK_8 - relative_rank(Us, s);
1066 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1067 mtg += blockerCount;
1069 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1071 movesToGo[Us] = mtg;
1077 // Rook pawns are a special case: They are sometimes worse, and
1078 // sometimes better than other passed pawns. It is difficult to find
1079 // good rules for determining whether they are good or bad. For now,
1080 // we try the following: Increase the value for rook pawns if the
1081 // other side has no pieces apart from a knight, and decrease the
1082 // value if the other side has a rook or queen.
1083 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1085 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1086 && pos.piece_count(Them, KNIGHT) <= 1)
1087 ebonus += ebonus / 4;
1088 else if (pos.pieces(ROOK, QUEEN, Them))
1089 ebonus -= ebonus / 4;
1092 // Add the scores for this pawn to the middle game and endgame eval.
1093 ei.mgValue += apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame);
1094 ei.egValue += apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame);
1100 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1102 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1104 int movesToGo[2] = {0, 0};
1105 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1107 // Evaluate pawns for each color
1108 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1109 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1111 // Neither side has an unstoppable passed pawn?
1112 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1115 // Does only one side have an unstoppable passed pawn?
1116 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1118 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1119 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide]));
1122 { // Both sides have unstoppable pawns! Try to find out who queens
1123 // first. We begin by transforming 'movesToGo' to the number of
1124 // plies until the pawn queens for both sides.
1125 movesToGo[WHITE] *= 2;
1126 movesToGo[BLACK] *= 2;
1127 movesToGo[pos.side_to_move()]--;
1129 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1130 Color loserSide = opposite_color(winnerSide);
1132 // If one side queens at least three plies before the other, that side wins
1133 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1134 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1136 // If one side queens one ply before the other and checks the king or attacks
1137 // the undefended opponent's queening square, that side wins. To avoid cases
1138 // where the opponent's king could move somewhere before first pawn queens we
1139 // consider only free paths to queen for both pawns.
1140 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1141 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1143 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1145 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1146 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1148 Bitboard b = pos.occupied_squares();
1149 clear_bit(&b, pawnToGo[winnerSide]);
1150 clear_bit(&b, pawnToGo[loserSide]);
1151 b = queen_attacks_bb(winnerQSq, b);
1153 if ( (b & pos.pieces(KING, loserSide))
1154 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1155 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1161 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1162 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1165 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1167 assert(square_is_ok(s));
1168 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1170 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1171 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1173 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1174 && pos.see(s, b6, false) < 0
1175 && pos.see(s, b8, false) < 0)
1177 ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
1178 ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
1183 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1184 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1185 // black), and assigns a penalty if it is. This pattern can obviously
1186 // only occur in Chess960 games.
1188 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1190 Piece pawn = piece_of_color_and_type(us, PAWN);
1194 assert(square_is_ok(s));
1195 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1197 if (square_file(s) == FILE_A)
1199 b2 = relative_square(us, SQ_B2);
1200 b3 = relative_square(us, SQ_B3);
1201 c3 = relative_square(us, SQ_C3);
1205 b2 = relative_square(us, SQ_G2);
1206 b3 = relative_square(us, SQ_G3);
1207 c3 = relative_square(us, SQ_F3);
1210 if (pos.piece_on(b2) == pawn)
1214 if (!pos.square_is_empty(b3))
1215 penalty = 2*TrappedBishopA1H1Penalty;
1216 else if (pos.piece_on(c3) == pawn)
1217 penalty = TrappedBishopA1H1Penalty;
1219 penalty = TrappedBishopA1H1Penalty / 2;
1221 ei.mgValue -= Sign[us] * penalty;
1222 ei.egValue -= Sign[us] * penalty;
1227 // evaluate_space() computes the space evaluation for a given side. The
1228 // space evaluation is a simple bonus based on the number of safe squares
1229 // available for minor pieces on the central four files on ranks 2--4. Safe
1230 // squares one, two or three squares behind a friendly pawn are counted
1231 // twice. Finally, the space bonus is scaled by a weight taken from the
1232 // material hash table.
1233 template<Color Us, bool HasPopCnt>
1234 void evaluate_space(const Position& pos, EvalInfo& ei) {
1236 const Color Them = (Us == WHITE ? BLACK : WHITE);
1238 // Find the safe squares for our pieces inside the area defined by
1239 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1240 // pawn, or if it is undefended and attacked by an enemy piece.
1242 Bitboard safeSquares = SpaceMask[Us]
1243 & ~pos.pieces(PAWN, Us)
1244 & ~ei.attacked_by(Them, PAWN)
1245 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1247 // Find all squares which are at most three squares behind some friendly
1249 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1250 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1251 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1253 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1254 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1256 ei.mgValue += Sign[Us] * apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
1260 // apply_weight() applies an evaluation weight to a value
1262 inline Value apply_weight(Value v, int w) {
1263 return (v*w) / 0x100;
1267 // scale_by_game_phase() interpolates between a middle game and an endgame
1268 // score, based on game phase. It also scales the return value by a
1269 // ScaleFactor array.
1271 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
1273 assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
1274 assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
1275 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1277 ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
1279 Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
1280 return Value(int(result) & ~(GrainSize - 1));
1284 // weight_option() computes the value of an evaluation weight, by combining
1285 // an UCI-configurable weight with an internal weight.
1287 int weight_option(const std::string& opt, int internalWeight) {
1289 int uciWeight = get_option_value_int(opt);
1290 uciWeight = (uciWeight * 0x100) / 100;
1291 return (uciWeight * internalWeight) / 0x100;
1295 // init_safety() initizes the king safety evaluation, based on UCI
1296 // parameters. It is called from read_weights().
1298 void init_safety() {
1300 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1301 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1302 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1303 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1304 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1305 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1306 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1308 int maxSlope = get_option_value_int("King Safety Max Slope");
1309 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1310 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1311 double b = get_option_value_int("King Safety X Intercept");
1312 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1313 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1315 for (int i = 0; i < 100; i++)
1318 SafetyTable[i] = Value(0);
1320 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1322 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1325 for (int i = 0; i < 100; i++)
1327 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1328 for (int j = i + 1; j < 100; j++)
1329 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1331 if (SafetyTable[i] > Value(peak))
1332 SafetyTable[i] = Value(peak);