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 Score apply_weight(Score v, int wmg, int weg);
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 = pos.value();
357 // Probe the material hash table
358 ei.mi = MaterialTable[threadID]->get_material_info(pos);
359 ei.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 += apply_weight(ei.pi->value(), WeightPawnStructureMidgame, WeightPawnStructureEndgame);
375 // Initialize king attack bitboards and king attack zones for both sides
376 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
377 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
378 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
379 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
381 // Initialize pawn attack bitboards for both sides
382 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
383 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
384 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
385 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
387 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
390 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
393 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
394 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
396 // Kings. Kings are evaluated after all other pieces for both sides,
397 // because we need complete attack information for all pieces when computing
398 // the king safety evaluation.
399 evaluate_king<WHITE, HasPopCnt>(pos, ei);
400 evaluate_king<BLACK, HasPopCnt>(pos, ei);
402 // Evaluate tactical threats, we need full attack info
403 evaluate_threats<WHITE>(pos, ei);
404 evaluate_threats<BLACK>(pos, ei);
406 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
407 // because we need to know which side promotes first in positions where
408 // both sides have an unstoppable passed pawn. To be called after all attacks
409 // are computed, included king.
410 if (ei.pi->passed_pawns())
411 evaluate_passed_pawns(pos, ei);
413 Phase phase = pos.game_phase();
415 // Middle-game specific evaluation terms
416 if (phase > PHASE_ENDGAME)
418 // Pawn storms in positions with opposite castling.
419 if ( square_file(pos.king_square(WHITE)) >= FILE_E
420 && square_file(pos.king_square(BLACK)) <= FILE_D)
422 ei.value += Score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
424 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
425 && square_file(pos.king_square(BLACK)) >= FILE_E)
427 ei.value += Score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
429 // Evaluate space for both sides
430 if (ei.mi->space_weight() > 0)
432 evaluate_space<WHITE, HasPopCnt>(pos, ei);
433 evaluate_space<BLACK, HasPopCnt>(pos, ei);
438 ei.value += apply_weight(Score(ei.mgMobility, ei.egMobility), WeightMobilityMidgame, WeightMobilityEndgame);
440 // If we don't already have an unusual scale factor, check for opposite
441 // colored bishop endgames, and use a lower scale for those
442 if ( phase < PHASE_MIDGAME
443 && pos.opposite_colored_bishops()
444 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.value.eg() > Value(0))
445 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.value.eg() < Value(0))))
449 // Only the two bishops ?
450 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
451 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
453 // Check for KBP vs KB with only a single pawn that is almost
454 // certainly a draw or at least two pawns.
455 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
456 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
459 // Endgame with opposite-colored bishops, but also other pieces. Still
460 // a bit drawish, but not as drawish as with only the two bishops.
461 sf = ScaleFactor(50);
463 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
465 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
469 // Interpolate between the middle game and the endgame score
470 Color stm = pos.side_to_move();
472 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
474 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
479 /// quick_evaluate() does a very approximate evaluation of the current position.
480 /// It currently considers only material and piece square table scores. Perhaps
481 /// we should add scores from the pawn and material hash tables?
483 Value quick_evaluate(const Position &pos) {
488 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
490 Phase ph = pos.game_phase();
491 Color stm = pos.side_to_move();
493 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
497 /// init_eval() initializes various tables used by the evaluation function
499 void init_eval(int threads) {
501 assert(threads <= THREAD_MAX);
503 for (int i = 0; i < THREAD_MAX; i++)
508 delete MaterialTable[i];
510 MaterialTable[i] = NULL;
514 PawnTable[i] = new PawnInfoTable(PawnTableSize);
515 if (!MaterialTable[i])
516 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
521 /// quit_eval() releases heap-allocated memory at program termination
525 for (int i = 0; i < THREAD_MAX; i++)
528 delete MaterialTable[i];
530 MaterialTable[i] = NULL;
535 /// read_weights() reads evaluation weights from the corresponding UCI parameters
537 void read_weights(Color us) {
539 Color them = opposite_color(us);
541 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
542 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
543 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
544 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
545 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
546 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
547 WeightSpace = weight_option("Space", WeightSpaceInternal);
548 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
549 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
551 // If running in analysis mode, make sure we use symmetrical king safety. We do this
552 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
553 if (get_option_value_bool("UCI_AnalyseMode"))
555 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
556 WeightKingSafety[them] = WeightKingSafety[us];
564 // evaluate_mobility() computes mobility and attacks for every piece
566 template<PieceType Piece, Color Us, bool HasPopCnt>
567 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
569 const Color Them = (Us == WHITE ? BLACK : WHITE);
570 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
571 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
572 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
574 // Update attack info
575 ei.attackedBy[Us][Piece] |= b;
578 if (b & ei.kingZone[Us])
580 ei.kingAttackersCount[Us]++;
581 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
582 Bitboard bb = (b & ei.attackedBy[Them][KING]);
584 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
588 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
589 : count_1s<HasPopCnt>(b & mob_area));
591 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
592 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
597 // evaluate_outposts() evaluates bishop and knight outposts squares
599 template<PieceType Piece, Color Us>
600 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
602 const Color Them = (Us == WHITE ? BLACK : WHITE);
604 // Initial bonus based on square
605 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
606 : KnightOutpostBonus[relative_square(Us, s)]);
608 // Increase bonus if supported by pawn, especially if the opponent has
609 // no minor piece which can exchange the outpost piece
610 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
612 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
613 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
614 bonus += bonus + bonus / 2;
618 ei.value += Sign[Us] * Score(bonus, bonus);
622 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
624 template<PieceType Piece, Color Us, bool HasPopCnt>
625 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
632 const Color Them = (Us == WHITE ? BLACK : WHITE);
633 const Square* ptr = pos.piece_list_begin(Us, Piece);
635 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
636 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
638 while ((s = *ptr++) != SQ_NONE)
640 if (Piece == KNIGHT || Piece == QUEEN)
641 b = pos.attacks_from<Piece>(s);
642 else if (Piece == BISHOP)
643 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
644 else if (Piece == ROOK)
645 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
649 // Attacks and mobility
650 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
652 // Decrease score if we are attacked by an enemy pawn. Remaining part
653 // of threat evaluation must be done later when we have full attack info.
654 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
655 ei.value -= Sign[Us] * Score(MidgameThreatedByPawnPenalty[Piece], EndgameThreatedByPawnPenalty[Piece]);
657 // Bishop and knight outposts squares
658 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
659 evaluate_outposts<Piece, Us>(pos, ei, s);
661 // Special patterns: trapped bishops on a7/h7/a2/h2
662 // and trapped bishops on a1/h1/a8/h8 in Chess960.
665 if (bit_is_set(MaskA7H7[Us], s))
666 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
668 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
669 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
672 if (Piece == ROOK || Piece == QUEEN)
674 // Queen or rook on 7th rank
675 if ( relative_rank(Us, s) == RANK_7
676 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
678 ei.value += Sign[Us] * (Piece == ROOK ? Score(MidgameRookOn7thBonus, EndgameRookOn7thBonus)
679 : Score(MidgameQueenOn7thBonus, EndgameQueenOn7thBonus));
683 // Special extra evaluation for rooks
686 // Open and half-open files
688 if (ei.pi->file_is_half_open(Us, f))
690 if (ei.pi->file_is_half_open(Them, f))
691 ei.value += Sign[Us] * Score(RookOpenFileBonus, RookOpenFileBonus);
693 ei.value += Sign[Us] * Score(RookHalfOpenFileBonus, RookHalfOpenFileBonus);
696 // Penalize rooks which are trapped inside a king. Penalize more if
697 // king has lost right to castle.
698 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
701 ksq = pos.king_square(Us);
703 if ( square_file(ksq) >= FILE_E
704 && square_file(s) > square_file(ksq)
705 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
707 // Is there a half-open file between the king and the edge of the board?
708 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
709 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
710 : (TrappedRookPenalty - mob * 16), 0);
712 else if ( square_file(ksq) <= FILE_D
713 && square_file(s) < square_file(ksq)
714 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
716 // Is there a half-open file between the king and the edge of the board?
717 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
718 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
719 : (TrappedRookPenalty - mob * 16), 0);
726 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
727 // and the type of attacked one.
730 void evaluate_threats(const Position& pos, EvalInfo& ei) {
732 const Color Them = (Us == WHITE ? BLACK : WHITE);
737 // Enemy pieces not defended by a pawn and under our attack
738 Bitboard weakEnemies = pos.pieces_of_color(Them)
739 & ~ei.attackedBy[Them][PAWN]
740 & ei.attackedBy[Us][0];
744 // Add bonus according to type of attacked enemy pieces and to the
745 // type of attacking piece, from knights to queens. Kings are not
746 // considered because are already special handled in king evaluation.
747 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
749 b = ei.attackedBy[Us][pt1] & weakEnemies;
751 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
752 if (b & pos.pieces(pt2))
753 bonus += Score(MidgameThreatBonus[pt1][pt2], EndgameThreatBonus[pt1][pt2]);
755 ei.value += Sign[Us] * bonus;
759 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
760 // pieces of a given color.
762 template<Color Us, bool HasPopCnt>
763 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
765 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
766 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
767 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
768 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
770 // Sum up all attacked squares
771 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
772 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
773 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
777 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
779 template<Color Us, bool HasPopCnt>
780 void evaluate_king(const Position& pos, EvalInfo& ei) {
782 const Color Them = (Us == WHITE ? BLACK : WHITE);
783 const Square s = pos.king_square(Us);
787 if (relative_rank(Us, s) <= RANK_4)
789 shelter = ei.pi->get_king_shelter(pos, Us, s);
790 ei.value += Sign[Us] * Score(shelter, 0);
793 // King safety. This is quite complicated, and is almost certainly far
794 // from optimally tuned.
795 if ( pos.piece_count(Them, QUEEN) >= 1
796 && ei.kingAttackersCount[Them] >= 2
797 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
798 && ei.kingAdjacentZoneAttacksCount[Them])
800 // Is it the attackers turn to move?
801 bool sente = (Them == pos.side_to_move());
803 // Find the attacked squares around the king which has no defenders
804 // apart from the king itself
805 Bitboard undefended =
806 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
807 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
808 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
809 & ei.attacked_by(Us, KING);
811 Bitboard occ = pos.occupied_squares(), b, b2;
813 // Initialize the 'attackUnits' variable, which is used later on as an
814 // index to the SafetyTable[] array. The initial value is based on the
815 // number and types of the attacking pieces, the number of attacked and
816 // undefended squares around the king, the square of the king, and the
817 // quality of the pawn shelter.
819 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
820 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
821 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
823 // Analyse safe queen contact checks
824 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
827 Bitboard attackedByOthers =
828 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
829 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
831 b &= attackedByOthers;
834 // The bitboard b now contains the squares available for safe queen
836 int count = count_1s_max_15<HasPopCnt>(b);
837 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
839 // Is there a mate threat?
840 if (QueenContactMates && !pos.is_check())
842 Bitboard escapeSquares =
843 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
847 Square from, to = pop_1st_bit(&b);
848 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
850 // We have a mate, unless the queen is pinned or there
851 // is an X-ray attack through the queen.
852 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
854 from = pos.piece_list(Them, QUEEN, i);
855 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
856 && !bit_is_set(pos.pinned_pieces(Them), from)
857 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
858 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
860 ei.mateThreat[Them] = make_move(from, to);
868 // Analyse safe distance checks
869 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
871 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
874 b2 = b & ei.attacked_by(Them, QUEEN);
876 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
879 b2 = b & ei.attacked_by(Them, ROOK);
881 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
883 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
885 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
888 b2 = b & ei.attacked_by(Them, QUEEN);
890 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
893 b2 = b & ei.attacked_by(Them, BISHOP);
895 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
897 if (KnightCheckBonus > 0)
899 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
902 b2 = b & ei.attacked_by(Them, KNIGHT);
904 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
907 // Analyse discovered checks (only for non-pawns right now, consider
908 // adding pawns later).
909 if (DiscoveredCheckBonus)
911 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
913 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
916 // Has a mate threat been found? We don't do anything here if the
917 // side with the mating move is the side to move, because in that
918 // case the mating side will get a huge bonus at the end of the main
919 // evaluation function instead.
920 if (ei.mateThreat[Them] != MOVE_NONE)
921 attackUnits += MateThreatBonus;
923 // Ensure that attackUnits is between 0 and 99, in order to avoid array
924 // out of bounds errors:
928 if (attackUnits >= 100)
931 // Finally, extract the king safety score from the SafetyTable[] array.
932 // Add the score to the evaluation, and also to ei.futilityMargin. The
933 // reason for adding the king safety score to the futility margin is
934 // that the king safety scores can sometimes be very big, and that
935 // capturing a single attacking piece can therefore result in a score
936 // change far bigger than the value of the captured piece.
937 Score v = apply_weight(Score(SafetyTable[attackUnits], 0), WeightKingSafety[Us], 0);
939 ei.value -= Sign[Us] * v;
941 if (Us == pos.side_to_move())
942 ei.futilityMargin += v.mg();
947 // evaluate_passed_pawns() evaluates the passed pawns of the given color
950 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
952 const Color Them = (Us == WHITE ? BLACK : WHITE);
955 Square ourKingSq = pos.king_square(Us);
956 Square theirKingSq = pos.king_square(Them);
957 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
961 Square s = pop_1st_bit(&b);
963 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
964 assert(pos.pawn_is_passed(Us, s));
966 int r = int(relative_rank(Us, s) - RANK_2);
967 int tr = Max(0, r * (r - 1));
969 // Base bonus based on rank
970 Value mbonus = Value(20 * tr);
971 Value ebonus = Value(10 + r * r * 10);
973 // Adjust bonus based on king proximity
976 Square blockSq = s + pawn_push(Us);
978 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
979 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
980 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
982 // If the pawn is free to advance, increase bonus
983 if (pos.square_is_empty(blockSq))
985 // There are no enemy pawns in the pawn's path
986 b2 = squares_in_front_of(Us, s);
988 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
990 // Squares attacked by us
991 b4 = b2 & ei.attacked_by(Us);
993 // Squares attacked or occupied by enemy pieces
994 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
996 // If there is an enemy rook or queen attacking the pawn from behind,
997 // add all X-ray attacks by the rook or queen.
998 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
999 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
1002 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
1003 if (b3 == EmptyBoardBB)
1004 // No enemy attacks or pieces, huge bonus!
1005 // Even bigger if we protect the pawn's path
1006 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
1008 // OK, there are enemy attacks or pieces (but not pawns). Are those
1009 // squares which are attacked by the enemy also attacked by us ?
1010 // If yes, big bonus (but smaller than when there are no enemy attacks),
1011 // if no, somewhat smaller bonus.
1012 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
1014 // At last, add a small bonus when there are no *friendly* pieces
1015 // in the pawn's path.
1016 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
1017 ebonus += Value(tr);
1021 // If the pawn is supported by a friendly pawn, increase bonus
1022 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
1023 if (b2 & rank_bb(s))
1024 ebonus += Value(r * 20);
1025 else if (pos.attacks_from<PAWN>(s, Them) & b2)
1026 ebonus += Value(r * 12);
1028 // If the other side has only a king, check whether the pawn is
1030 if (pos.non_pawn_material(Them) == Value(0))
1035 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1036 d = square_distance(s, qsq)
1037 - square_distance(theirKingSq, qsq)
1038 + (Us != pos.side_to_move());
1042 int mtg = RANK_8 - relative_rank(Us, s);
1043 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1044 mtg += blockerCount;
1046 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1048 movesToGo[Us] = mtg;
1054 // Rook pawns are a special case: They are sometimes worse, and
1055 // sometimes better than other passed pawns. It is difficult to find
1056 // good rules for determining whether they are good or bad. For now,
1057 // we try the following: Increase the value for rook pawns if the
1058 // other side has no pieces apart from a knight, and decrease the
1059 // value if the other side has a rook or queen.
1060 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1062 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1063 && pos.piece_count(Them, KNIGHT) <= 1)
1064 ebonus += ebonus / 4;
1065 else if (pos.pieces(ROOK, QUEEN, Them))
1066 ebonus -= ebonus / 4;
1069 // Add the scores for this pawn to the middle game and endgame eval.
1070 ei.value += Sign[Us] * apply_weight(Score(mbonus, ebonus), WeightPassedPawnsMidgame, WeightPassedPawnsEndgame);
1076 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1078 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1080 int movesToGo[2] = {0, 0};
1081 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1083 // Evaluate pawns for each color
1084 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1085 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1087 // Neither side has an unstoppable passed pawn?
1088 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1091 // Does only one side have an unstoppable passed pawn?
1092 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1094 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1095 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1098 { // Both sides have unstoppable pawns! Try to find out who queens
1099 // first. We begin by transforming 'movesToGo' to the number of
1100 // plies until the pawn queens for both sides.
1101 movesToGo[WHITE] *= 2;
1102 movesToGo[BLACK] *= 2;
1103 movesToGo[pos.side_to_move()]--;
1105 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1106 Color loserSide = opposite_color(winnerSide);
1108 // If one side queens at least three plies before the other, that side wins
1109 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1110 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1112 // If one side queens one ply before the other and checks the king or attacks
1113 // the undefended opponent's queening square, that side wins. To avoid cases
1114 // where the opponent's king could move somewhere before first pawn queens we
1115 // consider only free paths to queen for both pawns.
1116 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1117 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1119 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1121 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1122 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1124 Bitboard b = pos.occupied_squares();
1125 clear_bit(&b, pawnToGo[winnerSide]);
1126 clear_bit(&b, pawnToGo[loserSide]);
1127 b = queen_attacks_bb(winnerQSq, b);
1129 if ( (b & pos.pieces(KING, loserSide))
1130 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1131 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1137 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1138 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1141 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1143 assert(square_is_ok(s));
1144 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1146 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1147 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1149 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1150 && pos.see(s, b6) < 0
1151 && pos.see(s, b8) < 0)
1153 ei.value -= Sign[us] * Score(TrappedBishopA7H7Penalty, TrappedBishopA7H7Penalty);
1158 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1159 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1160 // black), and assigns a penalty if it is. This pattern can obviously
1161 // only occur in Chess960 games.
1163 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1165 Piece pawn = piece_of_color_and_type(us, PAWN);
1169 assert(square_is_ok(s));
1170 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1172 if (square_file(s) == FILE_A)
1174 b2 = relative_square(us, SQ_B2);
1175 b3 = relative_square(us, SQ_B3);
1176 c3 = relative_square(us, SQ_C3);
1180 b2 = relative_square(us, SQ_G2);
1181 b3 = relative_square(us, SQ_G3);
1182 c3 = relative_square(us, SQ_F3);
1185 if (pos.piece_on(b2) == pawn)
1189 if (!pos.square_is_empty(b3))
1190 penalty = 2*TrappedBishopA1H1Penalty;
1191 else if (pos.piece_on(c3) == pawn)
1192 penalty = TrappedBishopA1H1Penalty;
1194 penalty = TrappedBishopA1H1Penalty / 2;
1196 ei.value -= Sign[us] * Score(penalty, penalty);
1201 // evaluate_space() computes the space evaluation for a given side. The
1202 // space evaluation is a simple bonus based on the number of safe squares
1203 // available for minor pieces on the central four files on ranks 2--4. Safe
1204 // squares one, two or three squares behind a friendly pawn are counted
1205 // twice. Finally, the space bonus is scaled by a weight taken from the
1206 // material hash table.
1207 template<Color Us, bool HasPopCnt>
1208 void evaluate_space(const Position& pos, EvalInfo& ei) {
1210 const Color Them = (Us == WHITE ? BLACK : WHITE);
1212 // Find the safe squares for our pieces inside the area defined by
1213 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1214 // pawn, or if it is undefended and attacked by an enemy piece.
1216 Bitboard safeSquares = SpaceMask[Us]
1217 & ~pos.pieces(PAWN, Us)
1218 & ~ei.attacked_by(Them, PAWN)
1219 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1221 // Find all squares which are at most three squares behind some friendly
1223 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1224 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1225 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1227 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1228 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1230 ei.value += Sign[Us] * apply_weight(Score(space * ei.mi->space_weight(), 0), WeightSpace, 0);
1234 // apply_weight() applies an evaluation weight to a value
1236 inline Score apply_weight(Score v, int wmg, int weg) {
1237 return Score(v.mg() * wmg, v.eg() * weg) / 0x100;
1241 // scale_by_game_phase() interpolates between a middle game and an endgame
1242 // score, based on game phase. It also scales the return value by a
1243 // ScaleFactor array.
1245 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1247 assert(v.mg() > -VALUE_INFINITE && v.mg() < VALUE_INFINITE);
1248 assert(v.eg() > -VALUE_INFINITE && v.eg() < VALUE_INFINITE);
1249 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1251 Value ev = apply_scale_factor(v.eg(), sf[(v.eg() > Value(0) ? WHITE : BLACK)]);
1253 Value result = Value(int((v.mg() * ph + ev * (128 - ph)) / 128));
1254 return Value(int(result) & ~(GrainSize - 1));
1258 // weight_option() computes the value of an evaluation weight, by combining
1259 // an UCI-configurable weight with an internal weight.
1261 int weight_option(const std::string& opt, int internalWeight) {
1263 int uciWeight = get_option_value_int(opt);
1264 uciWeight = (uciWeight * 0x100) / 100;
1265 return (uciWeight * internalWeight) / 0x100;
1269 // init_safety() initizes the king safety evaluation, based on UCI
1270 // parameters. It is called from read_weights().
1272 void init_safety() {
1274 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1275 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1276 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1277 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1278 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1279 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1280 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1282 int maxSlope = get_option_value_int("King Safety Max Slope");
1283 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1284 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1285 double b = get_option_value_int("King Safety X Intercept");
1286 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1287 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1289 for (int i = 0; i < 100; i++)
1292 SafetyTable[i] = Value(0);
1294 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1296 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1299 for (int i = 0; i < 100; i++)
1301 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1302 for (int j = i + 1; j < 100; j++)
1303 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1305 if (SafetyTable[i] > Value(peak))
1306 SafetyTable[i] = Value(peak);
1311 std::ostream& operator<<(std::ostream &os, Score s) {
1313 return os << "(" << s.mg() << ", " << s.eg() << ")";