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 inline Score apply_weight(Score v, int wmg, int weg);
324 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
325 int weight_option(const std::string& opt, int weight);
334 /// evaluate() is the main evaluation function. It always computes two
335 /// values, an endgame score and a middle game score, and interpolates
336 /// between them based on the remaining material.
337 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
339 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
340 : do_evaluate<false>(pos, ei, threadID);
345 template<bool HasPopCnt>
346 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
349 assert(threadID >= 0 && threadID < THREAD_MAX);
350 assert(!pos.is_check());
352 memset(&ei, 0, sizeof(EvalInfo));
354 // Initialize by reading the incrementally updated scores included in the
355 // position object (material + piece square tables)
356 ei.value = pos.value();
358 // Probe the material hash table
359 ei.mi = MaterialTable[threadID]->get_material_info(pos);
360 ei.value += ei.mi->material_value();
362 // If we have a specialized evaluation function for the current material
363 // configuration, call it and return
364 if (ei.mi->specialized_eval_exists())
365 return ei.mi->evaluate(pos);
367 // After get_material_info() call that modifies them
368 ScaleFactor factor[2];
369 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
370 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
372 // Probe the pawn hash table
373 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
374 ei.value += apply_weight(ei.pi->value(), WeightPawnStructureMidgame, 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 += apply_weight(Score(ei.mgMobility, ei.egMobility), WeightMobilityMidgame, WeightMobilityEndgame);
441 // If we don't already have an unusual scale factor, check for opposite
442 // colored bishop endgames, and use a lower scale for those
443 if ( phase < PHASE_MIDGAME
444 && pos.opposite_colored_bishops()
445 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.value.eg() > Value(0))
446 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.value.eg() < Value(0))))
450 // Only the two bishops ?
451 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
452 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
454 // Check for KBP vs KB with only a single pawn that is almost
455 // certainly a draw or at least two pawns.
456 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
457 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
460 // Endgame with opposite-colored bishops, but also other pieces. Still
461 // a bit drawish, but not as drawish as with only the two bishops.
462 sf = ScaleFactor(50);
464 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
466 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
470 // Interpolate between the middle game and the endgame score
471 Color stm = pos.side_to_move();
473 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
475 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
480 /// quick_evaluate() does a very approximate evaluation of the current position.
481 /// It currently considers only material and piece square table scores. Perhaps
482 /// we should add scores from the pawn and material hash tables?
484 Value quick_evaluate(const Position &pos) {
489 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
491 Phase ph = pos.game_phase();
492 Color stm = pos.side_to_move();
494 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
498 /// init_eval() initializes various tables used by the evaluation function
500 void init_eval(int threads) {
502 assert(threads <= THREAD_MAX);
504 for (int i = 0; i < THREAD_MAX; i++)
509 delete MaterialTable[i];
511 MaterialTable[i] = NULL;
515 PawnTable[i] = new PawnInfoTable(PawnTableSize);
516 if (!MaterialTable[i])
517 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
522 /// quit_eval() releases heap-allocated memory at program termination
526 for (int i = 0; i < THREAD_MAX; i++)
529 delete MaterialTable[i];
531 MaterialTable[i] = NULL;
536 /// read_weights() reads evaluation weights from the corresponding UCI parameters
538 void read_weights(Color us) {
540 Color them = opposite_color(us);
542 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
543 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
544 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
545 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
546 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
547 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
548 WeightSpace = weight_option("Space", WeightSpaceInternal);
549 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
550 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
552 // If running in analysis mode, make sure we use symmetrical king safety. We do this
553 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
554 if (get_option_value_bool("UCI_AnalyseMode"))
556 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
557 WeightKingSafety[them] = WeightKingSafety[us];
565 // evaluate_mobility() computes mobility and attacks for every piece
567 template<PieceType Piece, Color Us, bool HasPopCnt>
568 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
570 const Color Them = (Us == WHITE ? BLACK : WHITE);
571 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
572 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
573 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
575 // Update attack info
576 ei.attackedBy[Us][Piece] |= b;
579 if (b & ei.kingZone[Us])
581 ei.kingAttackersCount[Us]++;
582 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
583 Bitboard bb = (b & ei.attackedBy[Them][KING]);
585 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
589 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
590 : count_1s<HasPopCnt>(b & mob_area));
592 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
593 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
598 // evaluate_outposts() evaluates bishop and knight outposts squares
600 template<PieceType Piece, Color Us>
601 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
603 const Color Them = (Us == WHITE ? BLACK : WHITE);
605 // Initial bonus based on square
606 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
607 : KnightOutpostBonus[relative_square(Us, s)]);
609 // Increase bonus if supported by pawn, especially if the opponent has
610 // no minor piece which can exchange the outpost piece
611 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
613 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
614 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
615 bonus += bonus + bonus / 2;
619 ei.value += Sign[Us] * Score(bonus, bonus);
623 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
625 template<PieceType Piece, Color Us, bool HasPopCnt>
626 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
633 const Color Them = (Us == WHITE ? BLACK : WHITE);
634 const Square* ptr = pos.piece_list_begin(Us, Piece);
636 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
637 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
639 while ((s = *ptr++) != SQ_NONE)
641 if (Piece == KNIGHT || Piece == QUEEN)
642 b = pos.attacks_from<Piece>(s);
643 else if (Piece == BISHOP)
644 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
645 else if (Piece == ROOK)
646 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
650 // Attacks and mobility
651 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
653 // Decrease score if we are attacked by an enemy pawn. Remaining part
654 // of threat evaluation must be done later when we have full attack info.
655 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
656 ei.value -= Sign[Us] * Score(MidgameThreatedByPawnPenalty[Piece], EndgameThreatedByPawnPenalty[Piece]);
658 // Bishop and knight outposts squares
659 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
660 evaluate_outposts<Piece, Us>(pos, ei, s);
662 // Special patterns: trapped bishops on a7/h7/a2/h2
663 // and trapped bishops on a1/h1/a8/h8 in Chess960.
666 if (bit_is_set(MaskA7H7[Us], s))
667 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
669 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
670 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
673 if (Piece == ROOK || Piece == QUEEN)
675 // Queen or rook on 7th rank
676 if ( relative_rank(Us, s) == RANK_7
677 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
679 ei.value += Sign[Us] * (Piece == ROOK ? Score(MidgameRookOn7thBonus, EndgameRookOn7thBonus)
680 : Score(MidgameQueenOn7thBonus, EndgameQueenOn7thBonus));
684 // Special extra evaluation for rooks
687 // Open and half-open files
689 if (ei.pi->file_is_half_open(Us, f))
691 if (ei.pi->file_is_half_open(Them, f))
692 ei.value += Sign[Us] * Score(RookOpenFileBonus, RookOpenFileBonus);
694 ei.value += Sign[Us] * Score(RookHalfOpenFileBonus, RookHalfOpenFileBonus);
697 // Penalize rooks which are trapped inside a king. Penalize more if
698 // king has lost right to castle.
699 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
702 ksq = pos.king_square(Us);
704 if ( square_file(ksq) >= FILE_E
705 && square_file(s) > square_file(ksq)
706 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
708 // Is there a half-open file between the king and the edge of the board?
709 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
710 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
711 : (TrappedRookPenalty - mob * 16), 0);
713 else if ( square_file(ksq) <= FILE_D
714 && square_file(s) < square_file(ksq)
715 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
717 // Is there a half-open file between the king and the edge of the board?
718 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
719 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
720 : (TrappedRookPenalty - mob * 16), 0);
727 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
728 // and the type of attacked one.
731 void evaluate_threats(const Position& pos, EvalInfo& ei) {
733 const Color Them = (Us == WHITE ? BLACK : WHITE);
738 // Enemy pieces not defended by a pawn and under our attack
739 Bitboard weakEnemies = pos.pieces_of_color(Them)
740 & ~ei.attackedBy[Them][PAWN]
741 & ei.attackedBy[Us][0];
745 // Add bonus according to type of attacked enemy pieces and to the
746 // type of attacking piece, from knights to queens. Kings are not
747 // considered because are already special handled in king evaluation.
748 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
750 b = ei.attackedBy[Us][pt1] & weakEnemies;
752 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
753 if (b & pos.pieces(pt2))
754 bonus += Score(MidgameThreatBonus[pt1][pt2], EndgameThreatBonus[pt1][pt2]);
756 ei.value += Sign[Us] * bonus;
760 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
761 // pieces of a given color.
763 template<Color Us, bool HasPopCnt>
764 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
766 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
767 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
768 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
769 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
771 // Sum up all attacked squares
772 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
773 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
774 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
778 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
780 template<Color Us, bool HasPopCnt>
781 void evaluate_king(const Position& pos, EvalInfo& ei) {
783 const Color Them = (Us == WHITE ? BLACK : WHITE);
784 const Square s = pos.king_square(Us);
788 if (relative_rank(Us, s) <= RANK_4)
790 shelter = ei.pi->get_king_shelter(pos, Us, s);
791 ei.value += Sign[Us] * Score(shelter, 0);
794 // King safety. This is quite complicated, and is almost certainly far
795 // from optimally tuned.
796 if ( pos.piece_count(Them, QUEEN) >= 1
797 && ei.kingAttackersCount[Them] >= 2
798 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
799 && ei.kingAdjacentZoneAttacksCount[Them])
801 // Is it the attackers turn to move?
802 bool sente = (Them == pos.side_to_move());
804 // Find the attacked squares around the king which has no defenders
805 // apart from the king itself
806 Bitboard undefended =
807 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
808 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
809 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
810 & ei.attacked_by(Us, KING);
812 Bitboard occ = pos.occupied_squares(), b, b2;
814 // Initialize the 'attackUnits' variable, which is used later on as an
815 // index to the SafetyTable[] array. The initial value is based on the
816 // number and types of the attacking pieces, the number of attacked and
817 // undefended squares around the king, the square of the king, and the
818 // quality of the pawn shelter.
820 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
821 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
822 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
824 // Analyse safe queen contact checks
825 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
828 Bitboard attackedByOthers =
829 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
830 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
832 b &= attackedByOthers;
835 // The bitboard b now contains the squares available for safe queen
837 int count = count_1s_max_15<HasPopCnt>(b);
838 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
840 // Is there a mate threat?
841 if (QueenContactMates && !pos.is_check())
843 Bitboard escapeSquares =
844 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
848 Square from, to = pop_1st_bit(&b);
849 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
851 // We have a mate, unless the queen is pinned or there
852 // is an X-ray attack through the queen.
853 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
855 from = pos.piece_list(Them, QUEEN, i);
856 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
857 && !bit_is_set(pos.pinned_pieces(Them), from)
858 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
859 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
861 ei.mateThreat[Them] = make_move(from, to);
869 // Analyse safe distance checks
870 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
872 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
875 b2 = b & ei.attacked_by(Them, QUEEN);
877 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
880 b2 = b & ei.attacked_by(Them, ROOK);
882 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
884 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
886 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
889 b2 = b & ei.attacked_by(Them, QUEEN);
891 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
894 b2 = b & ei.attacked_by(Them, BISHOP);
896 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
898 if (KnightCheckBonus > 0)
900 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
903 b2 = b & ei.attacked_by(Them, KNIGHT);
905 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
908 // Analyse discovered checks (only for non-pawns right now, consider
909 // adding pawns later).
910 if (DiscoveredCheckBonus)
912 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
914 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
917 // Has a mate threat been found? We don't do anything here if the
918 // side with the mating move is the side to move, because in that
919 // case the mating side will get a huge bonus at the end of the main
920 // evaluation function instead.
921 if (ei.mateThreat[Them] != MOVE_NONE)
922 attackUnits += MateThreatBonus;
924 // Ensure that attackUnits is between 0 and 99, in order to avoid array
925 // out of bounds errors:
929 if (attackUnits >= 100)
932 // Finally, extract the king safety score from the SafetyTable[] array.
933 // Add the score to the evaluation, and also to ei.futilityMargin. The
934 // reason for adding the king safety score to the futility margin is
935 // that the king safety scores can sometimes be very big, and that
936 // capturing a single attacking piece can therefore result in a score
937 // change far bigger than the value of the captured piece.
938 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
940 ei.value -= Sign[Us] * Score(v, 0);
942 if (Us == pos.side_to_move())
943 ei.futilityMargin += v;
948 // evaluate_passed_pawns() evaluates the passed pawns of the given color
951 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
953 const Color Them = (Us == WHITE ? BLACK : WHITE);
956 Square ourKingSq = pos.king_square(Us);
957 Square theirKingSq = pos.king_square(Them);
958 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
962 Square s = pop_1st_bit(&b);
964 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
965 assert(pos.pawn_is_passed(Us, s));
967 int r = int(relative_rank(Us, s) - RANK_2);
968 int tr = Max(0, r * (r - 1));
970 // Base bonus based on rank
971 Value mbonus = Value(20 * tr);
972 Value ebonus = Value(10 + r * r * 10);
974 // Adjust bonus based on king proximity
977 Square blockSq = s + pawn_push(Us);
979 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
980 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
981 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
983 // If the pawn is free to advance, increase bonus
984 if (pos.square_is_empty(blockSq))
986 // There are no enemy pawns in the pawn's path
987 b2 = squares_in_front_of(Us, s);
989 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
991 // Squares attacked by us
992 b4 = b2 & ei.attacked_by(Us);
994 // Squares attacked or occupied by enemy pieces
995 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
997 // If there is an enemy rook or queen attacking the pawn from behind,
998 // add all X-ray attacks by the rook or queen.
999 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
1000 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
1003 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
1004 if (b3 == EmptyBoardBB)
1005 // No enemy attacks or pieces, huge bonus!
1006 // Even bigger if we protect the pawn's path
1007 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
1009 // OK, there are enemy attacks or pieces (but not pawns). Are those
1010 // squares which are attacked by the enemy also attacked by us ?
1011 // If yes, big bonus (but smaller than when there are no enemy attacks),
1012 // if no, somewhat smaller bonus.
1013 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
1015 // At last, add a small bonus when there are no *friendly* pieces
1016 // in the pawn's path.
1017 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
1018 ebonus += Value(tr);
1022 // If the pawn is supported by a friendly pawn, increase bonus
1023 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
1024 if (b2 & rank_bb(s))
1025 ebonus += Value(r * 20);
1026 else if (pos.attacks_from<PAWN>(s, Them) & b2)
1027 ebonus += Value(r * 12);
1029 // If the other side has only a king, check whether the pawn is
1031 if (pos.non_pawn_material(Them) == Value(0))
1036 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1037 d = square_distance(s, qsq)
1038 - square_distance(theirKingSq, qsq)
1039 + (Us != pos.side_to_move());
1043 int mtg = RANK_8 - relative_rank(Us, s);
1044 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1045 mtg += blockerCount;
1047 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1049 movesToGo[Us] = mtg;
1055 // Rook pawns are a special case: They are sometimes worse, and
1056 // sometimes better than other passed pawns. It is difficult to find
1057 // good rules for determining whether they are good or bad. For now,
1058 // we try the following: Increase the value for rook pawns if the
1059 // other side has no pieces apart from a knight, and decrease the
1060 // value if the other side has a rook or queen.
1061 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1063 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1064 && pos.piece_count(Them, KNIGHT) <= 1)
1065 ebonus += ebonus / 4;
1066 else if (pos.pieces(ROOK, QUEEN, Them))
1067 ebonus -= ebonus / 4;
1070 // Add the scores for this pawn to the middle game and endgame eval.
1071 ei.value += Score(apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame),
1072 apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame));
1078 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1080 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1082 int movesToGo[2] = {0, 0};
1083 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1085 // Evaluate pawns for each color
1086 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1087 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1089 // Neither side has an unstoppable passed pawn?
1090 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1093 // Does only one side have an unstoppable passed pawn?
1094 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1096 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1097 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1100 { // Both sides have unstoppable pawns! Try to find out who queens
1101 // first. We begin by transforming 'movesToGo' to the number of
1102 // plies until the pawn queens for both sides.
1103 movesToGo[WHITE] *= 2;
1104 movesToGo[BLACK] *= 2;
1105 movesToGo[pos.side_to_move()]--;
1107 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1108 Color loserSide = opposite_color(winnerSide);
1110 // If one side queens at least three plies before the other, that side wins
1111 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1112 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1114 // If one side queens one ply before the other and checks the king or attacks
1115 // the undefended opponent's queening square, that side wins. To avoid cases
1116 // where the opponent's king could move somewhere before first pawn queens we
1117 // consider only free paths to queen for both pawns.
1118 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1119 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1121 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1123 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1124 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1126 Bitboard b = pos.occupied_squares();
1127 clear_bit(&b, pawnToGo[winnerSide]);
1128 clear_bit(&b, pawnToGo[loserSide]);
1129 b = queen_attacks_bb(winnerQSq, b);
1131 if ( (b & pos.pieces(KING, loserSide))
1132 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1133 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1139 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1140 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1143 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1145 assert(square_is_ok(s));
1146 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1148 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1149 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1151 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1152 && pos.see(s, b6) < 0
1153 && pos.see(s, b8) < 0)
1155 ei.value -= Sign[us] * Score(TrappedBishopA7H7Penalty, TrappedBishopA7H7Penalty);
1160 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1161 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1162 // black), and assigns a penalty if it is. This pattern can obviously
1163 // only occur in Chess960 games.
1165 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1167 Piece pawn = piece_of_color_and_type(us, PAWN);
1171 assert(square_is_ok(s));
1172 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1174 if (square_file(s) == FILE_A)
1176 b2 = relative_square(us, SQ_B2);
1177 b3 = relative_square(us, SQ_B3);
1178 c3 = relative_square(us, SQ_C3);
1182 b2 = relative_square(us, SQ_G2);
1183 b3 = relative_square(us, SQ_G3);
1184 c3 = relative_square(us, SQ_F3);
1187 if (pos.piece_on(b2) == pawn)
1191 if (!pos.square_is_empty(b3))
1192 penalty = 2*TrappedBishopA1H1Penalty;
1193 else if (pos.piece_on(c3) == pawn)
1194 penalty = TrappedBishopA1H1Penalty;
1196 penalty = TrappedBishopA1H1Penalty / 2;
1198 ei.value -= Sign[us] * Score(penalty, penalty);
1203 // evaluate_space() computes the space evaluation for a given side. The
1204 // space evaluation is a simple bonus based on the number of safe squares
1205 // available for minor pieces on the central four files on ranks 2--4. Safe
1206 // squares one, two or three squares behind a friendly pawn are counted
1207 // twice. Finally, the space bonus is scaled by a weight taken from the
1208 // material hash table.
1209 template<Color Us, bool HasPopCnt>
1210 void evaluate_space(const Position& pos, EvalInfo& ei) {
1212 const Color Them = (Us == WHITE ? BLACK : WHITE);
1214 // Find the safe squares for our pieces inside the area defined by
1215 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1216 // pawn, or if it is undefended and attacked by an enemy piece.
1218 Bitboard safeSquares = SpaceMask[Us]
1219 & ~pos.pieces(PAWN, Us)
1220 & ~ei.attacked_by(Them, PAWN)
1221 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1223 // Find all squares which are at most three squares behind some friendly
1225 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1226 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1227 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1229 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1230 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1232 ei.value += Sign[Us] * Score(apply_weight(Value(space * ei.mi->space_weight()), WeightSpace), 0);
1236 // apply_weight() applies an evaluation weight to a value
1238 inline Value apply_weight(Value v, int w) {
1239 return (v*w) / 0x100;
1242 inline Score apply_weight(Score v, int wmg, int weg) {
1243 return Score(v.mg()*wmg, v.eg()*weg) / 0x100;
1247 // scale_by_game_phase() interpolates between a middle game and an endgame
1248 // score, based on game phase. It also scales the return value by a
1249 // ScaleFactor array.
1251 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1253 assert(v.mg() > -VALUE_INFINITE && v.mg() < VALUE_INFINITE);
1254 assert(v.eg() > -VALUE_INFINITE && v.eg() < VALUE_INFINITE);
1255 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1257 Value ev = apply_scale_factor(v.eg(), sf[(v.eg() > Value(0) ? WHITE : BLACK)]);
1259 Value result = Value(int((v.mg() * ph + ev * (128 - ph)) / 128));
1260 return Value(int(result) & ~(GrainSize - 1));
1264 // weight_option() computes the value of an evaluation weight, by combining
1265 // an UCI-configurable weight with an internal weight.
1267 int weight_option(const std::string& opt, int internalWeight) {
1269 int uciWeight = get_option_value_int(opt);
1270 uciWeight = (uciWeight * 0x100) / 100;
1271 return (uciWeight * internalWeight) / 0x100;
1275 // init_safety() initizes the king safety evaluation, based on UCI
1276 // parameters. It is called from read_weights().
1278 void init_safety() {
1280 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1281 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1282 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1283 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1284 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1285 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1286 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1288 int maxSlope = get_option_value_int("King Safety Max Slope");
1289 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1290 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1291 double b = get_option_value_int("King Safety X Intercept");
1292 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1293 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1295 for (int i = 0; i < 100; i++)
1298 SafetyTable[i] = Value(0);
1300 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1302 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1305 for (int i = 0; i < 100; i++)
1307 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1308 for (int j = i + 1; j < 100; j++)
1309 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1311 if (SafetyTable[i] > Value(peak))
1312 SafetyTable[i] = Value(peak);
1317 std::ostream& operator<<(std::ostream &os, Score s) {
1319 return os << "(" << s.mg() << ", " << s.eg() << ")";