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 = pos.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 Phase ph = pos.game_phase();
493 Color stm = pos.side_to_move();
495 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
499 /// init_eval() initializes various tables used by the evaluation function
501 void init_eval(int threads) {
503 assert(threads <= THREAD_MAX);
505 for (int i = 0; i < THREAD_MAX; i++)
510 delete MaterialTable[i];
512 MaterialTable[i] = NULL;
516 PawnTable[i] = new PawnInfoTable(PawnTableSize);
517 if (!MaterialTable[i])
518 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
523 /// quit_eval() releases heap-allocated memory at program termination
527 for (int i = 0; i < THREAD_MAX; i++)
530 delete MaterialTable[i];
532 MaterialTable[i] = NULL;
537 /// read_weights() reads evaluation weights from the corresponding UCI parameters
539 void read_weights(Color us) {
541 Color them = opposite_color(us);
543 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
544 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
545 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
546 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
547 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
548 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
549 WeightSpace = weight_option("Space", WeightSpaceInternal);
550 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
551 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
553 // If running in analysis mode, make sure we use symmetrical king safety. We do this
554 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
555 if (get_option_value_bool("UCI_AnalyseMode"))
557 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
558 WeightKingSafety[them] = WeightKingSafety[us];
566 // evaluate_mobility() computes mobility and attacks for every piece
568 template<PieceType Piece, Color Us, bool HasPopCnt>
569 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
571 const Color Them = (Us == WHITE ? BLACK : WHITE);
572 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
573 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
574 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
576 // Update attack info
577 ei.attackedBy[Us][Piece] |= b;
580 if (b & ei.kingZone[Us])
582 ei.kingAttackersCount[Us]++;
583 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
584 Bitboard bb = (b & ei.attackedBy[Them][KING]);
586 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
590 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
591 : count_1s<HasPopCnt>(b & mob_area));
593 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
594 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
599 // evaluate_outposts() evaluates bishop and knight outposts squares
601 template<PieceType Piece, Color Us>
602 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
604 const Color Them = (Us == WHITE ? BLACK : WHITE);
606 // Initial bonus based on square
607 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
608 : KnightOutpostBonus[relative_square(Us, s)]);
610 // Increase bonus if supported by pawn, especially if the opponent has
611 // no minor piece which can exchange the outpost piece
612 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
614 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
615 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
616 bonus += bonus + bonus / 2;
620 ei.value += Sign[Us] * Score(bonus, bonus);
624 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
626 template<PieceType Piece, Color Us, bool HasPopCnt>
627 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
634 const Color Them = (Us == WHITE ? BLACK : WHITE);
635 const Square* ptr = pos.piece_list_begin(Us, Piece);
637 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
638 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
640 while ((s = *ptr++) != SQ_NONE)
642 if (Piece == KNIGHT || Piece == QUEEN)
643 b = pos.attacks_from<Piece>(s);
644 else if (Piece == BISHOP)
645 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
646 else if (Piece == ROOK)
647 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
651 // Attacks and mobility
652 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
654 // Decrease score if we are attacked by an enemy pawn. Remaining part
655 // of threat evaluation must be done later when we have full attack info.
656 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
657 ei.value -= Sign[Us] * Score(MidgameThreatedByPawnPenalty[Piece], EndgameThreatedByPawnPenalty[Piece]);
659 // Bishop and knight outposts squares
660 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
661 evaluate_outposts<Piece, Us>(pos, ei, s);
663 // Special patterns: trapped bishops on a7/h7/a2/h2
664 // and trapped bishops on a1/h1/a8/h8 in Chess960.
667 if (bit_is_set(MaskA7H7[Us], s))
668 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
670 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
671 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
674 if (Piece == ROOK || Piece == QUEEN)
676 // Queen or rook on 7th rank
677 if ( relative_rank(Us, s) == RANK_7
678 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
680 ei.value += Sign[Us] * (Piece == ROOK ? Score(MidgameRookOn7thBonus, EndgameRookOn7thBonus)
681 : Score(MidgameQueenOn7thBonus, EndgameQueenOn7thBonus));
685 // Special extra evaluation for rooks
688 // Open and half-open files
690 if (ei.pi->file_is_half_open(Us, f))
692 if (ei.pi->file_is_half_open(Them, f))
693 ei.value += Sign[Us] * Score(RookOpenFileBonus, RookOpenFileBonus);
695 ei.value += Sign[Us] * Score(RookHalfOpenFileBonus, RookHalfOpenFileBonus);
698 // Penalize rooks which are trapped inside a king. Penalize more if
699 // king has lost right to castle.
700 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
703 ksq = pos.king_square(Us);
705 if ( square_file(ksq) >= FILE_E
706 && square_file(s) > square_file(ksq)
707 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
709 // Is there a half-open file between the king and the edge of the board?
710 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
711 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
712 : (TrappedRookPenalty - mob * 16), 0);
714 else if ( square_file(ksq) <= FILE_D
715 && square_file(s) < square_file(ksq)
716 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
718 // Is there a half-open file between the king and the edge of the board?
719 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
720 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
721 : (TrappedRookPenalty - mob * 16), 0);
728 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
729 // and the type of attacked one.
732 void evaluate_threats(const Position& pos, EvalInfo& ei) {
734 const Color Them = (Us == WHITE ? BLACK : WHITE);
739 // Enemy pieces not defended by a pawn and under our attack
740 Bitboard weakEnemies = pos.pieces_of_color(Them)
741 & ~ei.attackedBy[Them][PAWN]
742 & ei.attackedBy[Us][0];
746 // Add bonus according to type of attacked enemy pieces and to the
747 // type of attacking piece, from knights to queens. Kings are not
748 // considered because are already special handled in king evaluation.
749 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
751 b = ei.attackedBy[Us][pt1] & weakEnemies;
753 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
754 if (b & pos.pieces(pt2))
755 bonus += Score(MidgameThreatBonus[pt1][pt2], EndgameThreatBonus[pt1][pt2]);
757 ei.value += Sign[Us] * bonus;
761 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
762 // pieces of a given color.
764 template<Color Us, bool HasPopCnt>
765 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
767 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
768 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
769 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
770 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
772 // Sum up all attacked squares
773 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
774 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
775 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
779 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
781 template<Color Us, bool HasPopCnt>
782 void evaluate_king(const Position& pos, EvalInfo& ei) {
784 const Color Them = (Us == WHITE ? BLACK : WHITE);
785 const Square s = pos.king_square(Us);
789 if (relative_rank(Us, s) <= RANK_4)
791 shelter = ei.pi->get_king_shelter(pos, Us, s);
792 ei.value += Score(Sign[Us] * Value(shelter), 0);
795 // King safety. This is quite complicated, and is almost certainly far
796 // from optimally tuned.
797 if ( pos.piece_count(Them, QUEEN) >= 1
798 && ei.kingAttackersCount[Them] >= 2
799 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
800 && ei.kingAdjacentZoneAttacksCount[Them])
802 // Is it the attackers turn to move?
803 bool sente = (Them == pos.side_to_move());
805 // Find the attacked squares around the king which has no defenders
806 // apart from the king itself
807 Bitboard undefended =
808 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
809 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
810 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
811 & ei.attacked_by(Us, KING);
813 Bitboard occ = pos.occupied_squares(), b, b2;
815 // Initialize the 'attackUnits' variable, which is used later on as an
816 // index to the SafetyTable[] array. The initial value is based on the
817 // number and types of the attacking pieces, the number of attacked and
818 // undefended squares around the king, the square of the king, and the
819 // quality of the pawn shelter.
821 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
822 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
823 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
825 // Analyse safe queen contact checks
826 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
829 Bitboard attackedByOthers =
830 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
831 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
833 b &= attackedByOthers;
836 // The bitboard b now contains the squares available for safe queen
838 int count = count_1s_max_15<HasPopCnt>(b);
839 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
841 // Is there a mate threat?
842 if (QueenContactMates && !pos.is_check())
844 Bitboard escapeSquares =
845 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
849 Square from, to = pop_1st_bit(&b);
850 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
852 // We have a mate, unless the queen is pinned or there
853 // is an X-ray attack through the queen.
854 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
856 from = pos.piece_list(Them, QUEEN, i);
857 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
858 && !bit_is_set(pos.pinned_pieces(Them), from)
859 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
860 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
862 ei.mateThreat[Them] = make_move(from, to);
870 // Analyse safe distance checks
871 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
873 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
876 b2 = b & ei.attacked_by(Them, QUEEN);
878 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
881 b2 = b & ei.attacked_by(Them, ROOK);
883 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
885 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
887 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
890 b2 = b & ei.attacked_by(Them, QUEEN);
892 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
895 b2 = b & ei.attacked_by(Them, BISHOP);
897 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
899 if (KnightCheckBonus > 0)
901 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
904 b2 = b & ei.attacked_by(Them, KNIGHT);
906 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
909 // Analyse discovered checks (only for non-pawns right now, consider
910 // adding pawns later).
911 if (DiscoveredCheckBonus)
913 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
915 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
918 // Has a mate threat been found? We don't do anything here if the
919 // side with the mating move is the side to move, because in that
920 // case the mating side will get a huge bonus at the end of the main
921 // evaluation function instead.
922 if (ei.mateThreat[Them] != MOVE_NONE)
923 attackUnits += MateThreatBonus;
925 // Ensure that attackUnits is between 0 and 99, in order to avoid array
926 // out of bounds errors:
930 if (attackUnits >= 100)
933 // Finally, extract the king safety score from the SafetyTable[] array.
934 // Add the score to the evaluation, and also to ei.futilityMargin. The
935 // reason for adding the king safety score to the futility margin is
936 // that the king safety scores can sometimes be very big, and that
937 // capturing a single attacking piece can therefore result in a score
938 // change far bigger than the value of the captured piece.
939 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
941 ei.value -= Score(Sign[Us] * v, 0);
943 if (Us == pos.side_to_move())
944 ei.futilityMargin += v;
949 // evaluate_passed_pawns() evaluates the passed pawns of the given color
952 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
954 const Color Them = (Us == WHITE ? BLACK : WHITE);
957 Square ourKingSq = pos.king_square(Us);
958 Square theirKingSq = pos.king_square(Them);
959 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
963 Square s = pop_1st_bit(&b);
965 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
966 assert(pos.pawn_is_passed(Us, s));
968 int r = int(relative_rank(Us, s) - RANK_2);
969 int tr = Max(0, r * (r - 1));
971 // Base bonus based on rank
972 Value mbonus = Value(20 * tr);
973 Value ebonus = Value(10 + r * r * 10);
975 // Adjust bonus based on king proximity
978 Square blockSq = s + pawn_push(Us);
980 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
981 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
982 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
984 // If the pawn is free to advance, increase bonus
985 if (pos.square_is_empty(blockSq))
987 // There are no enemy pawns in the pawn's path
988 b2 = squares_in_front_of(Us, s);
990 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
992 // Squares attacked by us
993 b4 = b2 & ei.attacked_by(Us);
995 // Squares attacked or occupied by enemy pieces
996 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
998 // If there is an enemy rook or queen attacking the pawn from behind,
999 // add all X-ray attacks by the rook or queen.
1000 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
1001 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
1004 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
1005 if (b3 == EmptyBoardBB)
1006 // No enemy attacks or pieces, huge bonus!
1007 // Even bigger if we protect the pawn's path
1008 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
1010 // OK, there are enemy attacks or pieces (but not pawns). Are those
1011 // squares which are attacked by the enemy also attacked by us ?
1012 // If yes, big bonus (but smaller than when there are no enemy attacks),
1013 // if no, somewhat smaller bonus.
1014 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
1016 // At last, add a small bonus when there are no *friendly* pieces
1017 // in the pawn's path.
1018 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
1019 ebonus += Value(tr);
1023 // If the pawn is supported by a friendly pawn, increase bonus
1024 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
1025 if (b2 & rank_bb(s))
1026 ebonus += Value(r * 20);
1027 else if (pos.attacks_from<PAWN>(s, Them) & b2)
1028 ebonus += Value(r * 12);
1030 // If the other side has only a king, check whether the pawn is
1032 if (pos.non_pawn_material(Them) == Value(0))
1037 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1038 d = square_distance(s, qsq)
1039 - square_distance(theirKingSq, qsq)
1040 + (Us != pos.side_to_move());
1044 int mtg = RANK_8 - relative_rank(Us, s);
1045 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1046 mtg += blockerCount;
1048 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1050 movesToGo[Us] = mtg;
1056 // Rook pawns are a special case: They are sometimes worse, and
1057 // sometimes better than other passed pawns. It is difficult to find
1058 // good rules for determining whether they are good or bad. For now,
1059 // we try the following: Increase the value for rook pawns if the
1060 // other side has no pieces apart from a knight, and decrease the
1061 // value if the other side has a rook or queen.
1062 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1064 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1065 && pos.piece_count(Them, KNIGHT) <= 1)
1066 ebonus += ebonus / 4;
1067 else if (pos.pieces(ROOK, QUEEN, Them))
1068 ebonus -= ebonus / 4;
1071 // Add the scores for this pawn to the middle game and endgame eval.
1072 ei.value += Score(apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame),
1073 apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame));
1079 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1081 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1083 int movesToGo[2] = {0, 0};
1084 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1086 // Evaluate pawns for each color
1087 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1088 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1090 // Neither side has an unstoppable passed pawn?
1091 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1094 // Does only one side have an unstoppable passed pawn?
1095 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1097 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1098 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1101 { // Both sides have unstoppable pawns! Try to find out who queens
1102 // first. We begin by transforming 'movesToGo' to the number of
1103 // plies until the pawn queens for both sides.
1104 movesToGo[WHITE] *= 2;
1105 movesToGo[BLACK] *= 2;
1106 movesToGo[pos.side_to_move()]--;
1108 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1109 Color loserSide = opposite_color(winnerSide);
1111 // If one side queens at least three plies before the other, that side wins
1112 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1113 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1115 // If one side queens one ply before the other and checks the king or attacks
1116 // the undefended opponent's queening square, that side wins. To avoid cases
1117 // where the opponent's king could move somewhere before first pawn queens we
1118 // consider only free paths to queen for both pawns.
1119 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1120 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1122 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1124 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1125 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1127 Bitboard b = pos.occupied_squares();
1128 clear_bit(&b, pawnToGo[winnerSide]);
1129 clear_bit(&b, pawnToGo[loserSide]);
1130 b = queen_attacks_bb(winnerQSq, b);
1132 if ( (b & pos.pieces(KING, loserSide))
1133 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1134 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1140 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1141 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1144 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1146 assert(square_is_ok(s));
1147 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1149 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1150 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1152 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1153 && pos.see(s, b6) < 0
1154 && pos.see(s, b8) < 0)
1156 ei.value -= Sign[us] * Score(TrappedBishopA7H7Penalty, TrappedBishopA7H7Penalty);
1161 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1162 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1163 // black), and assigns a penalty if it is. This pattern can obviously
1164 // only occur in Chess960 games.
1166 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1168 Piece pawn = piece_of_color_and_type(us, PAWN);
1172 assert(square_is_ok(s));
1173 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1175 if (square_file(s) == FILE_A)
1177 b2 = relative_square(us, SQ_B2);
1178 b3 = relative_square(us, SQ_B3);
1179 c3 = relative_square(us, SQ_C3);
1183 b2 = relative_square(us, SQ_G2);
1184 b3 = relative_square(us, SQ_G3);
1185 c3 = relative_square(us, SQ_F3);
1188 if (pos.piece_on(b2) == pawn)
1192 if (!pos.square_is_empty(b3))
1193 penalty = 2*TrappedBishopA1H1Penalty;
1194 else if (pos.piece_on(c3) == pawn)
1195 penalty = TrappedBishopA1H1Penalty;
1197 penalty = TrappedBishopA1H1Penalty / 2;
1199 ei.value -= Sign[us] * Score(penalty, penalty);
1204 // evaluate_space() computes the space evaluation for a given side. The
1205 // space evaluation is a simple bonus based on the number of safe squares
1206 // available for minor pieces on the central four files on ranks 2--4. Safe
1207 // squares one, two or three squares behind a friendly pawn are counted
1208 // twice. Finally, the space bonus is scaled by a weight taken from the
1209 // material hash table.
1210 template<Color Us, bool HasPopCnt>
1211 void evaluate_space(const Position& pos, EvalInfo& ei) {
1213 const Color Them = (Us == WHITE ? BLACK : WHITE);
1215 // Find the safe squares for our pieces inside the area defined by
1216 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1217 // pawn, or if it is undefended and attacked by an enemy piece.
1219 Bitboard safeSquares = SpaceMask[Us]
1220 & ~pos.pieces(PAWN, Us)
1221 & ~ei.attacked_by(Them, PAWN)
1222 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1224 // Find all squares which are at most three squares behind some friendly
1226 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1227 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1228 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1230 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1231 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1233 ei.value += Sign[Us] * Score(apply_weight(Value(space * ei.mi->space_weight()), WeightSpace), 0);
1237 // apply_weight() applies an evaluation weight to a value
1239 inline Value apply_weight(Value v, int w) {
1240 return (v*w) / 0x100;
1244 // scale_by_game_phase() interpolates between a middle game and an endgame
1245 // score, based on game phase. It also scales the return value by a
1246 // ScaleFactor array.
1248 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1250 assert(v.mg() > -VALUE_INFINITE && v.mg() < VALUE_INFINITE);
1251 assert(v.eg() > -VALUE_INFINITE && v.eg() < VALUE_INFINITE);
1252 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1254 Value ev = apply_scale_factor(v.eg(), sf[(v.eg() > Value(0) ? WHITE : BLACK)]);
1256 Value result = Value(int((v.mg() * ph + ev * (128 - ph)) / 128));
1257 return Value(int(result) & ~(GrainSize - 1));
1261 // weight_option() computes the value of an evaluation weight, by combining
1262 // an UCI-configurable weight with an internal weight.
1264 int weight_option(const std::string& opt, int internalWeight) {
1266 int uciWeight = get_option_value_int(opt);
1267 uciWeight = (uciWeight * 0x100) / 100;
1268 return (uciWeight * internalWeight) / 0x100;
1272 // init_safety() initizes the king safety evaluation, based on UCI
1273 // parameters. It is called from read_weights().
1275 void init_safety() {
1277 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1278 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1279 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1280 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1281 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1282 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1283 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1285 int maxSlope = get_option_value_int("King Safety Max Slope");
1286 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1287 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1288 double b = get_option_value_int("King Safety X Intercept");
1289 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1290 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1292 for (int i = 0; i < 100; i++)
1295 SafetyTable[i] = Value(0);
1297 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1299 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1302 for (int i = 0; i < 100; i++)
1304 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1305 for (int j = i + 1; j < 100; j++)
1306 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1308 if (SafetyTable[i] > Value(peak))
1309 SafetyTable[i] = Value(peak);
1314 std::ostream& operator<<(std::ostream &os, Score s) {
1316 return os << "(" << s.mg() << ", " << s.eg() << ")";