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(const Score& v, 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.value = Score(pos.mg_value(), pos.eg_value());
357 // Probe the material hash table
358 ei.mi = MaterialTable[threadID]->get_material_info(pos);
359 ei.value += Score(ei.mi->material_value(), ei.mi->material_value());
361 // If we have a specialized evaluation function for the current material
362 // configuration, call it and return
363 if (ei.mi->specialized_eval_exists())
364 return ei.mi->evaluate(pos);
366 // After get_material_info() call that modifies them
367 ScaleFactor factor[2];
368 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
369 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
371 // Probe the pawn hash table
372 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
373 ei.value += Score(apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame),
374 apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame));
376 // Initialize king attack bitboards and king attack zones for both sides
377 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
378 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
379 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
380 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
382 // Initialize pawn attack bitboards for both sides
383 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
384 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
385 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
386 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
388 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
391 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
394 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
395 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
397 // Kings. Kings are evaluated after all other pieces for both sides,
398 // because we need complete attack information for all pieces when computing
399 // the king safety evaluation.
400 evaluate_king<WHITE, HasPopCnt>(pos, ei);
401 evaluate_king<BLACK, HasPopCnt>(pos, ei);
403 // Evaluate tactical threats, we need full attack info
404 evaluate_threats<WHITE>(pos, ei);
405 evaluate_threats<BLACK>(pos, ei);
407 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
408 // because we need to know which side promotes first in positions where
409 // both sides have an unstoppable passed pawn. To be called after all attacks
410 // are computed, included king.
411 if (ei.pi->passed_pawns())
412 evaluate_passed_pawns(pos, ei);
414 Phase phase = pos.game_phase();
416 // Middle-game specific evaluation terms
417 if (phase > PHASE_ENDGAME)
419 // Pawn storms in positions with opposite castling.
420 if ( square_file(pos.king_square(WHITE)) >= FILE_E
421 && square_file(pos.king_square(BLACK)) <= FILE_D)
423 ei.value += Score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
425 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
426 && square_file(pos.king_square(BLACK)) >= FILE_E)
428 ei.value += Score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
430 // Evaluate space for both sides
431 if (ei.mi->space_weight() > 0)
433 evaluate_space<WHITE, HasPopCnt>(pos, ei);
434 evaluate_space<BLACK, HasPopCnt>(pos, ei);
439 ei.value += Score(apply_weight(ei.mgMobility, WeightMobilityMidgame),
440 apply_weight(ei.egMobility, WeightMobilityEndgame));
442 // If we don't already have an unusual scale factor, check for opposite
443 // colored bishop endgames, and use a lower scale for those
444 if ( phase < PHASE_MIDGAME
445 && pos.opposite_colored_bishops()
446 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.value.eg() > Value(0))
447 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.value.eg() < Value(0))))
451 // Only the two bishops ?
452 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
453 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
455 // Check for KBP vs KB with only a single pawn that is almost
456 // certainly a draw or at least two pawns.
457 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
458 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
461 // Endgame with opposite-colored bishops, but also other pieces. Still
462 // a bit drawish, but not as drawish as with only the two bishops.
463 sf = ScaleFactor(50);
465 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
467 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
471 // Interpolate between the middle game and the endgame score
472 Color stm = pos.side_to_move();
474 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
476 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
481 /// quick_evaluate() does a very approximate evaluation of the current position.
482 /// It currently considers only material and piece square table scores. Perhaps
483 /// we should add scores from the pawn and material hash tables?
485 Value quick_evaluate(const Position &pos) {
490 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
492 Score v = Score(pos.mg_value(), pos.eg_value());
493 Phase ph = pos.game_phase();
494 Color stm = pos.side_to_move();
496 return Sign[stm] * scale_by_game_phase(v, ph, sf);
500 /// init_eval() initializes various tables used by the evaluation function
502 void init_eval(int threads) {
504 assert(threads <= THREAD_MAX);
506 for (int i = 0; i < THREAD_MAX; i++)
511 delete MaterialTable[i];
513 MaterialTable[i] = NULL;
517 PawnTable[i] = new PawnInfoTable(PawnTableSize);
518 if (!MaterialTable[i])
519 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
524 /// quit_eval() releases heap-allocated memory at program termination
528 for (int i = 0; i < THREAD_MAX; i++)
531 delete MaterialTable[i];
533 MaterialTable[i] = NULL;
538 /// read_weights() reads evaluation weights from the corresponding UCI parameters
540 void read_weights(Color us) {
542 Color them = opposite_color(us);
544 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
545 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
546 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
547 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
548 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
549 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
550 WeightSpace = weight_option("Space", WeightSpaceInternal);
551 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
552 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
554 // If running in analysis mode, make sure we use symmetrical king safety. We do this
555 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
556 if (get_option_value_bool("UCI_AnalyseMode"))
558 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
559 WeightKingSafety[them] = WeightKingSafety[us];
567 // evaluate_mobility() computes mobility and attacks for every piece
569 template<PieceType Piece, Color Us, bool HasPopCnt>
570 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
572 const Color Them = (Us == WHITE ? BLACK : WHITE);
573 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
574 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
575 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
577 // Update attack info
578 ei.attackedBy[Us][Piece] |= b;
581 if (b & ei.kingZone[Us])
583 ei.kingAttackersCount[Us]++;
584 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
585 Bitboard bb = (b & ei.attackedBy[Them][KING]);
587 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
591 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
592 : count_1s<HasPopCnt>(b & mob_area));
594 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
595 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
600 // evaluate_outposts() evaluates bishop and knight outposts squares
602 template<PieceType Piece, Color Us>
603 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
605 const Color Them = (Us == WHITE ? BLACK : WHITE);
607 // Initial bonus based on square
608 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
609 : KnightOutpostBonus[relative_square(Us, s)]);
611 // Increase bonus if supported by pawn, especially if the opponent has
612 // no minor piece which can exchange the outpost piece
613 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
615 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
616 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
617 bonus += bonus + bonus / 2;
621 ei.value += Sign[Us] * Score(bonus, bonus);
625 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
627 template<PieceType Piece, Color Us, bool HasPopCnt>
628 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
635 const Color Them = (Us == WHITE ? BLACK : WHITE);
636 const Square* ptr = pos.piece_list_begin(Us, Piece);
638 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
639 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
641 while ((s = *ptr++) != SQ_NONE)
643 if (Piece == KNIGHT || Piece == QUEEN)
644 b = pos.attacks_from<Piece>(s);
645 else if (Piece == BISHOP)
646 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
647 else if (Piece == ROOK)
648 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
652 // Attacks and mobility
653 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
655 // Decrease score if we are attacked by an enemy pawn. Remaining part
656 // of threat evaluation must be done later when we have full attack info.
657 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
658 ei.value -= Sign[Us] * Score(MidgameThreatedByPawnPenalty[Piece], EndgameThreatedByPawnPenalty[Piece]);
660 // Bishop and knight outposts squares
661 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
662 evaluate_outposts<Piece, Us>(pos, ei, s);
664 // Special patterns: trapped bishops on a7/h7/a2/h2
665 // and trapped bishops on a1/h1/a8/h8 in Chess960.
668 if (bit_is_set(MaskA7H7[Us], s))
669 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
671 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
672 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
675 if (Piece == ROOK || Piece == QUEEN)
677 // Queen or rook on 7th rank
678 if ( relative_rank(Us, s) == RANK_7
679 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
681 ei.value += Sign[Us] * (Piece == ROOK ? Score(MidgameRookOn7thBonus, EndgameRookOn7thBonus)
682 : Score(MidgameQueenOn7thBonus, EndgameQueenOn7thBonus));
686 // Special extra evaluation for rooks
689 // Open and half-open files
691 if (ei.pi->file_is_half_open(Us, f))
693 if (ei.pi->file_is_half_open(Them, f))
694 ei.value += Sign[Us] * Score(RookOpenFileBonus, RookOpenFileBonus);
696 ei.value += Sign[Us] * Score(RookHalfOpenFileBonus, RookHalfOpenFileBonus);
699 // Penalize rooks which are trapped inside a king. Penalize more if
700 // king has lost right to castle.
701 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
704 ksq = pos.king_square(Us);
706 if ( square_file(ksq) >= FILE_E
707 && square_file(s) > square_file(ksq)
708 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
710 // Is there a half-open file between the king and the edge of the board?
711 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
712 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
713 : (TrappedRookPenalty - mob * 16), 0);
715 else if ( square_file(ksq) <= FILE_D
716 && square_file(s) < square_file(ksq)
717 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
719 // Is there a half-open file between the king and the edge of the board?
720 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
721 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
722 : (TrappedRookPenalty - mob * 16), 0);
729 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
730 // and the type of attacked one.
733 void evaluate_threats(const Position& pos, EvalInfo& ei) {
735 const Color Them = (Us == WHITE ? BLACK : WHITE);
740 // Enemy pieces not defended by a pawn and under our attack
741 Bitboard weakEnemies = pos.pieces_of_color(Them)
742 & ~ei.attackedBy[Them][PAWN]
743 & ei.attackedBy[Us][0];
747 // Add bonus according to type of attacked enemy pieces and to the
748 // type of attacking piece, from knights to queens. Kings are not
749 // considered because are already special handled in king evaluation.
750 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
752 b = ei.attackedBy[Us][pt1] & weakEnemies;
754 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
755 if (b & pos.pieces(pt2))
756 bonus += Score(MidgameThreatBonus[pt1][pt2], EndgameThreatBonus[pt1][pt2]);
758 ei.value += Sign[Us] * bonus;
762 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
763 // pieces of a given color.
765 template<Color Us, bool HasPopCnt>
766 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
768 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
769 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
770 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
771 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
773 // Sum up all attacked squares
774 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
775 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
776 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
780 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
782 template<Color Us, bool HasPopCnt>
783 void evaluate_king(const Position& pos, EvalInfo& ei) {
785 const Color Them = (Us == WHITE ? BLACK : WHITE);
786 const Square s = pos.king_square(Us);
790 if (relative_rank(Us, s) <= RANK_4)
792 shelter = ei.pi->get_king_shelter(pos, Us, s);
793 ei.value += Score(Sign[Us] * Value(shelter), 0);
796 // King safety. This is quite complicated, and is almost certainly far
797 // from optimally tuned.
798 if ( pos.piece_count(Them, QUEEN) >= 1
799 && ei.kingAttackersCount[Them] >= 2
800 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
801 && ei.kingAdjacentZoneAttacksCount[Them])
803 // Is it the attackers turn to move?
804 bool sente = (Them == pos.side_to_move());
806 // Find the attacked squares around the king which has no defenders
807 // apart from the king itself
808 Bitboard undefended =
809 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
810 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
811 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
812 & ei.attacked_by(Us, KING);
814 Bitboard occ = pos.occupied_squares(), b, b2;
816 // Initialize the 'attackUnits' variable, which is used later on as an
817 // index to the SafetyTable[] array. The initial value is based on the
818 // number and types of the attacking pieces, the number of attacked and
819 // undefended squares around the king, the square of the king, and the
820 // quality of the pawn shelter.
822 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
823 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
824 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
826 // Analyse safe queen contact checks
827 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
830 Bitboard attackedByOthers =
831 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
832 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
834 b &= attackedByOthers;
837 // The bitboard b now contains the squares available for safe queen
839 int count = count_1s_max_15<HasPopCnt>(b);
840 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
842 // Is there a mate threat?
843 if (QueenContactMates && !pos.is_check())
845 Bitboard escapeSquares =
846 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
850 Square from, to = pop_1st_bit(&b);
851 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
853 // We have a mate, unless the queen is pinned or there
854 // is an X-ray attack through the queen.
855 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
857 from = pos.piece_list(Them, QUEEN, i);
858 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
859 && !bit_is_set(pos.pinned_pieces(Them), from)
860 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
861 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
863 ei.mateThreat[Them] = make_move(from, to);
871 // Analyse safe distance checks
872 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
874 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
877 b2 = b & ei.attacked_by(Them, QUEEN);
879 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
882 b2 = b & ei.attacked_by(Them, ROOK);
884 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
886 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
888 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
891 b2 = b & ei.attacked_by(Them, QUEEN);
893 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
896 b2 = b & ei.attacked_by(Them, BISHOP);
898 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
900 if (KnightCheckBonus > 0)
902 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
905 b2 = b & ei.attacked_by(Them, KNIGHT);
907 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
910 // Analyse discovered checks (only for non-pawns right now, consider
911 // adding pawns later).
912 if (DiscoveredCheckBonus)
914 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
916 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
919 // Has a mate threat been found? We don't do anything here if the
920 // side with the mating move is the side to move, because in that
921 // case the mating side will get a huge bonus at the end of the main
922 // evaluation function instead.
923 if (ei.mateThreat[Them] != MOVE_NONE)
924 attackUnits += MateThreatBonus;
926 // Ensure that attackUnits is between 0 and 99, in order to avoid array
927 // out of bounds errors:
931 if (attackUnits >= 100)
934 // Finally, extract the king safety score from the SafetyTable[] array.
935 // Add the score to the evaluation, and also to ei.futilityMargin. The
936 // reason for adding the king safety score to the futility margin is
937 // that the king safety scores can sometimes be very big, and that
938 // capturing a single attacking piece can therefore result in a score
939 // change far bigger than the value of the captured piece.
940 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
942 ei.value -= Score(Sign[Us] * v, 0);
944 if (Us == pos.side_to_move())
945 ei.futilityMargin += v;
950 // evaluate_passed_pawns() evaluates the passed pawns of the given color
953 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
955 const Color Them = (Us == WHITE ? BLACK : WHITE);
958 Square ourKingSq = pos.king_square(Us);
959 Square theirKingSq = pos.king_square(Them);
960 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
964 Square s = pop_1st_bit(&b);
966 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
967 assert(pos.pawn_is_passed(Us, s));
969 int r = int(relative_rank(Us, s) - RANK_2);
970 int tr = Max(0, r * (r - 1));
972 // Base bonus based on rank
973 Value mbonus = Value(20 * tr);
974 Value ebonus = Value(10 + r * r * 10);
976 // Adjust bonus based on king proximity
979 Square blockSq = s + pawn_push(Us);
981 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
982 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
983 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
985 // If the pawn is free to advance, increase bonus
986 if (pos.square_is_empty(blockSq))
988 // There are no enemy pawns in the pawn's path
989 b2 = squares_in_front_of(Us, s);
991 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
993 // Squares attacked by us
994 b4 = b2 & ei.attacked_by(Us);
996 // Squares attacked or occupied by enemy pieces
997 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
999 // If there is an enemy rook or queen attacking the pawn from behind,
1000 // add all X-ray attacks by the rook or queen.
1001 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
1002 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
1005 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
1006 if (b3 == EmptyBoardBB)
1007 // No enemy attacks or pieces, huge bonus!
1008 // Even bigger if we protect the pawn's path
1009 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
1011 // OK, there are enemy attacks or pieces (but not pawns). Are those
1012 // squares which are attacked by the enemy also attacked by us ?
1013 // If yes, big bonus (but smaller than when there are no enemy attacks),
1014 // if no, somewhat smaller bonus.
1015 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
1017 // At last, add a small bonus when there are no *friendly* pieces
1018 // in the pawn's path.
1019 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
1020 ebonus += Value(tr);
1024 // If the pawn is supported by a friendly pawn, increase bonus
1025 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
1026 if (b2 & rank_bb(s))
1027 ebonus += Value(r * 20);
1028 else if (pos.attacks_from<PAWN>(s, Them) & b2)
1029 ebonus += Value(r * 12);
1031 // If the other side has only a king, check whether the pawn is
1033 if (pos.non_pawn_material(Them) == Value(0))
1038 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1039 d = square_distance(s, qsq)
1040 - square_distance(theirKingSq, qsq)
1041 + (Us != pos.side_to_move());
1045 int mtg = RANK_8 - relative_rank(Us, s);
1046 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1047 mtg += blockerCount;
1049 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1051 movesToGo[Us] = mtg;
1057 // Rook pawns are a special case: They are sometimes worse, and
1058 // sometimes better than other passed pawns. It is difficult to find
1059 // good rules for determining whether they are good or bad. For now,
1060 // we try the following: Increase the value for rook pawns if the
1061 // other side has no pieces apart from a knight, and decrease the
1062 // value if the other side has a rook or queen.
1063 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1065 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1066 && pos.piece_count(Them, KNIGHT) <= 1)
1067 ebonus += ebonus / 4;
1068 else if (pos.pieces(ROOK, QUEEN, Them))
1069 ebonus -= ebonus / 4;
1072 // Add the scores for this pawn to the middle game and endgame eval.
1073 ei.value += Score(apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame),
1074 apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame));
1080 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1082 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1084 int movesToGo[2] = {0, 0};
1085 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1087 // Evaluate pawns for each color
1088 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1089 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1091 // Neither side has an unstoppable passed pawn?
1092 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1095 // Does only one side have an unstoppable passed pawn?
1096 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1098 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1099 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1102 { // Both sides have unstoppable pawns! Try to find out who queens
1103 // first. We begin by transforming 'movesToGo' to the number of
1104 // plies until the pawn queens for both sides.
1105 movesToGo[WHITE] *= 2;
1106 movesToGo[BLACK] *= 2;
1107 movesToGo[pos.side_to_move()]--;
1109 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1110 Color loserSide = opposite_color(winnerSide);
1112 // If one side queens at least three plies before the other, that side wins
1113 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1114 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1116 // If one side queens one ply before the other and checks the king or attacks
1117 // the undefended opponent's queening square, that side wins. To avoid cases
1118 // where the opponent's king could move somewhere before first pawn queens we
1119 // consider only free paths to queen for both pawns.
1120 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1121 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1123 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1125 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1126 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1128 Bitboard b = pos.occupied_squares();
1129 clear_bit(&b, pawnToGo[winnerSide]);
1130 clear_bit(&b, pawnToGo[loserSide]);
1131 b = queen_attacks_bb(winnerQSq, b);
1133 if ( (b & pos.pieces(KING, loserSide))
1134 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1135 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1141 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1142 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1145 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1147 assert(square_is_ok(s));
1148 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1150 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1151 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1153 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1154 && pos.see(s, b6) < 0
1155 && pos.see(s, b8) < 0)
1157 ei.value -= Sign[us] * Score(TrappedBishopA7H7Penalty, TrappedBishopA7H7Penalty);
1162 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1163 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1164 // black), and assigns a penalty if it is. This pattern can obviously
1165 // only occur in Chess960 games.
1167 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1169 Piece pawn = piece_of_color_and_type(us, PAWN);
1173 assert(square_is_ok(s));
1174 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1176 if (square_file(s) == FILE_A)
1178 b2 = relative_square(us, SQ_B2);
1179 b3 = relative_square(us, SQ_B3);
1180 c3 = relative_square(us, SQ_C3);
1184 b2 = relative_square(us, SQ_G2);
1185 b3 = relative_square(us, SQ_G3);
1186 c3 = relative_square(us, SQ_F3);
1189 if (pos.piece_on(b2) == pawn)
1193 if (!pos.square_is_empty(b3))
1194 penalty = 2*TrappedBishopA1H1Penalty;
1195 else if (pos.piece_on(c3) == pawn)
1196 penalty = TrappedBishopA1H1Penalty;
1198 penalty = TrappedBishopA1H1Penalty / 2;
1200 ei.value -= Sign[us] * Score(penalty, penalty);
1205 // evaluate_space() computes the space evaluation for a given side. The
1206 // space evaluation is a simple bonus based on the number of safe squares
1207 // available for minor pieces on the central four files on ranks 2--4. Safe
1208 // squares one, two or three squares behind a friendly pawn are counted
1209 // twice. Finally, the space bonus is scaled by a weight taken from the
1210 // material hash table.
1211 template<Color Us, bool HasPopCnt>
1212 void evaluate_space(const Position& pos, EvalInfo& ei) {
1214 const Color Them = (Us == WHITE ? BLACK : WHITE);
1216 // Find the safe squares for our pieces inside the area defined by
1217 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1218 // pawn, or if it is undefended and attacked by an enemy piece.
1220 Bitboard safeSquares = SpaceMask[Us]
1221 & ~pos.pieces(PAWN, Us)
1222 & ~ei.attacked_by(Them, PAWN)
1223 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1225 // Find all squares which are at most three squares behind some friendly
1227 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1228 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1229 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1231 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1232 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1234 ei.value += Sign[Us] * Score(apply_weight(Value(space * ei.mi->space_weight()), WeightSpace), 0);
1238 // apply_weight() applies an evaluation weight to a value
1240 inline Value apply_weight(Value v, int w) {
1241 return (v*w) / 0x100;
1245 // scale_by_game_phase() interpolates between a middle game and an endgame
1246 // score, based on game phase. It also scales the return value by a
1247 // ScaleFactor array.
1249 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1251 assert(v.mg() > -VALUE_INFINITE && v.mg() < VALUE_INFINITE);
1252 assert(v.eg() > -VALUE_INFINITE && v.eg() < VALUE_INFINITE);
1253 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1255 Value ev = apply_scale_factor(v.eg(), sf[(v.eg() > Value(0) ? WHITE : BLACK)]);
1257 Value result = Value(int((v.mg() * ph + ev * (128 - ph)) / 128));
1258 return Value(int(result) & ~(GrainSize - 1));
1262 // weight_option() computes the value of an evaluation weight, by combining
1263 // an UCI-configurable weight with an internal weight.
1265 int weight_option(const std::string& opt, int internalWeight) {
1267 int uciWeight = get_option_value_int(opt);
1268 uciWeight = (uciWeight * 0x100) / 100;
1269 return (uciWeight * internalWeight) / 0x100;
1273 // init_safety() initizes the king safety evaluation, based on UCI
1274 // parameters. It is called from read_weights().
1276 void init_safety() {
1278 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1279 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1280 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1281 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1282 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1283 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1284 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1286 int maxSlope = get_option_value_int("King Safety Max Slope");
1287 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1288 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1289 double b = get_option_value_int("King Safety X Intercept");
1290 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1291 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1293 for (int i = 0; i < 100; i++)
1296 SafetyTable[i] = Value(0);
1298 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1300 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1303 for (int i = 0; i < 100; i++)
1305 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1306 for (int j = i + 1; j < 100; j++)
1307 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1309 if (SafetyTable[i] > Value(peak))
1310 SafetyTable[i] = Value(peak);
1315 std::ostream& operator<<(std::ostream &os, Score s) {
1317 return os << "(" << s.mg() << ", " << s.eg() << ")";