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(30), V(0),V(50), V(70), V(70), V(0), V(0), // KNIGHT attacks
249 V(0),V(30),V(50), V(0), V(70), V(70), V(0), V(0), // BISHOP attacks
250 V(0),V(20),V(40),V(40), V(0), V(50), V(0), V(0), // ROOK attacks
251 V(0),V(40),V(40),V(40), V(40), 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(40), V(0),V(50),V(100),V(100), V(0), V(0), // KNIGHT attacks
260 V(0),V(40),V(50), V(0),V(100),V(100), V(0), V(0), // BISHOP attacks
261 V(0),V(30),V(50),V(50), V(0), V(50), V(0), V(0), // ROOK attacks
262 V(0),V(40),V(40),V(40), V(40), 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(50), V(50), V(70), V(80), V(0), V(0)
274 const Value EndgameThreatedByPawnPenalty[8] = {
275 V(0), V(0), V(70), V(70), V(100), V(120), 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);
313 template<Color Us, bool HasPopCnt>
314 void evaluate_space(const Position& pos, EvalInfo& ei);
316 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
317 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
318 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
319 inline Value apply_weight(Value v, int w);
320 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
321 int weight_option(const std::string& opt, int weight);
330 /// evaluate() is the main evaluation function. It always computes two
331 /// values, an endgame score and a middle game score, and interpolates
332 /// between them based on the remaining material.
333 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
335 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
336 : do_evaluate<false>(pos, ei, threadID);
341 template<bool HasPopCnt>
342 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
345 assert(threadID >= 0 && threadID < THREAD_MAX);
346 assert(!pos.is_check());
348 memset(&ei, 0, sizeof(EvalInfo));
350 // Initialize by reading the incrementally updated scores included in the
351 // position object (material + piece square tables)
352 ei.mgValue = pos.mg_value();
353 ei.egValue = pos.eg_value();
355 // Probe the material hash table
356 ei.mi = MaterialTable[threadID]->get_material_info(pos);
357 ei.mgValue += ei.mi->material_value();
358 ei.egValue += ei.mi->material_value();
360 // If we have a specialized evaluation function for the current material
361 // configuration, call it and return
362 if (ei.mi->specialized_eval_exists())
363 return ei.mi->evaluate(pos);
365 // After get_material_info() call that modifies them
366 ScaleFactor factor[2];
367 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
368 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
370 // Probe the pawn hash table
371 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
372 ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
373 ei.egValue += apply_weight(ei.pi->eg_value(), 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.mgValue += ei.pi->queenside_storm_value(WHITE)
423 - ei.pi->kingside_storm_value(BLACK);
425 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
426 && square_file(pos.king_square(BLACK)) >= FILE_E)
428 ei.mgValue += ei.pi->kingside_storm_value(WHITE)
429 - ei.pi->queenside_storm_value(BLACK);
431 // Evaluate space for both sides
432 if (ei.mi->space_weight() > 0)
434 evaluate_space<WHITE, HasPopCnt>(pos, ei);
435 evaluate_space<BLACK, HasPopCnt>(pos, ei);
440 ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
441 ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
443 // If we don't already have an unusual scale factor, check for opposite
444 // colored bishop endgames, and use a lower scale for those
445 if ( phase < PHASE_MIDGAME
446 && pos.opposite_colored_bishops()
447 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
448 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
452 // Only the two bishops ?
453 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
454 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
456 // Check for KBP vs KB with only a single pawn that is almost
457 // certainly a draw or at least two pawns.
458 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
459 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
462 // Endgame with opposite-colored bishops, but also other pieces. Still
463 // a bit drawish, but not as drawish as with only the two bishops.
464 sf = ScaleFactor(50);
466 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
468 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
472 // Interpolate between the middle game and the endgame score
473 Color stm = pos.side_to_move();
475 Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
477 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
482 /// quick_evaluate() does a very approximate evaluation of the current position.
483 /// It currently considers only material and piece square table scores. Perhaps
484 /// we should add scores from the pawn and material hash tables?
486 Value quick_evaluate(const Position &pos) {
491 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
493 Value mgv = pos.mg_value();
494 Value egv = pos.eg_value();
495 Phase ph = pos.game_phase();
496 Color stm = pos.side_to_move();
498 return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
502 /// init_eval() initializes various tables used by the evaluation function
504 void init_eval(int threads) {
506 assert(threads <= THREAD_MAX);
508 for (int i = 0; i < THREAD_MAX; i++)
513 delete MaterialTable[i];
515 MaterialTable[i] = NULL;
519 PawnTable[i] = new PawnInfoTable(PawnTableSize);
520 if (!MaterialTable[i])
521 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
526 /// quit_eval() releases heap-allocated memory at program termination
530 for (int i = 0; i < THREAD_MAX; i++)
533 delete MaterialTable[i];
535 MaterialTable[i] = NULL;
540 /// read_weights() reads evaluation weights from the corresponding UCI parameters
542 void read_weights(Color us) {
544 Color them = opposite_color(us);
546 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
547 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
548 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
549 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
550 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
551 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
552 WeightSpace = weight_option("Space", WeightSpaceInternal);
553 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
554 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
556 // If running in analysis mode, make sure we use symmetrical king safety. We do this
557 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
558 if (get_option_value_bool("UCI_AnalyseMode"))
560 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
561 WeightKingSafety[them] = WeightKingSafety[us];
569 // evaluate_mobility() computes mobility and attacks for every piece
571 template<PieceType Piece, Color Us, bool HasPopCnt>
572 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
574 const Color Them = (Us == WHITE ? BLACK : WHITE);
575 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
576 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
577 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
579 // Update attack info
580 ei.attackedBy[Us][Piece] |= b;
583 if (b & ei.kingZone[Us])
585 ei.kingAttackersCount[Us]++;
586 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
587 Bitboard bb = (b & ei.attackedBy[Them][KING]);
589 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
593 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
594 : count_1s<HasPopCnt>(b & mob_area));
596 ei.mgMobility += Sign[Us] * MgBonus[Piece][mob];
597 ei.egMobility += Sign[Us] * EgBonus[Piece][mob];
602 // evaluate_outposts() evaluates bishop and knight outposts squares
604 template<PieceType Piece, Color Us>
605 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
607 const Color Them = (Us == WHITE ? BLACK : WHITE);
609 // Initial bonus based on square
610 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
611 : KnightOutpostBonus[relative_square(Us, s)]);
613 // Increase bonus if supported by pawn, especially if the opponent has
614 // no minor piece which can exchange the outpost piece
615 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
617 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
618 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
619 bonus += bonus + bonus / 2;
623 ei.mgValue += Sign[Us] * bonus;
624 ei.egValue += Sign[Us] * bonus;
628 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
630 template<PieceType Piece, Color Us, bool HasPopCnt>
631 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
638 const Color Them = (Us == WHITE ? BLACK : WHITE);
639 const Square* ptr = pos.piece_list_begin(Us, Piece);
641 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
642 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
644 while ((s = *ptr++) != SQ_NONE)
646 if (Piece == KNIGHT || Piece == QUEEN)
647 b = pos.attacks_from<Piece>(s);
648 else if (Piece == BISHOP)
649 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
650 else if (Piece == ROOK)
651 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
655 // Attacks and mobility
656 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
658 // Decrease score if we are attacked by an enemy pawn. Remaining part
659 // of threat evaluation must be done later when we have full attack info.
660 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
662 ei.mgValue -= Sign[Us] * MidgameThreatedByPawnPenalty[Piece];
663 ei.egValue -= Sign[Us] * EndgameThreatedByPawnPenalty[Piece];
666 // Bishop and knight outposts squares
667 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
668 evaluate_outposts<Piece, Us>(pos, ei, s);
670 // Special patterns: trapped bishops on a7/h7/a2/h2
671 // and trapped bishops on a1/h1/a8/h8 in Chess960.
674 if (bit_is_set(MaskA7H7[Us], s))
675 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
677 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
678 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
681 if (Piece == ROOK || Piece == QUEEN)
683 // Queen or rook on 7th rank
684 if ( relative_rank(Us, s) == RANK_7
685 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
687 ei.mgValue += Sign[Us] * (Piece == ROOK ? MidgameRookOn7thBonus : MidgameQueenOn7thBonus);
688 ei.egValue += Sign[Us] * (Piece == ROOK ? EndgameRookOn7thBonus : EndgameQueenOn7thBonus);
692 // Special extra evaluation for rooks
695 // Open and half-open files
697 if (ei.pi->file_is_half_open(Us, f))
699 if (ei.pi->file_is_half_open(Them, f))
701 ei.mgValue += Sign[Us] * RookOpenFileBonus;
702 ei.egValue += Sign[Us] * RookOpenFileBonus;
706 ei.mgValue += Sign[Us] * RookHalfOpenFileBonus;
707 ei.egValue += Sign[Us] * RookHalfOpenFileBonus;
711 // Penalize rooks which are trapped inside a king. Penalize more if
712 // king has lost right to castle.
713 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
716 ksq = pos.king_square(Us);
718 if ( square_file(ksq) >= FILE_E
719 && square_file(s) > square_file(ksq)
720 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
722 // Is there a half-open file between the king and the edge of the board?
723 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
724 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
725 : Sign[Us] * (TrappedRookPenalty - mob * 16);
727 else if ( square_file(ksq) <= FILE_D
728 && square_file(s) < square_file(ksq)
729 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
731 // Is there a half-open file between the king and the edge of the board?
732 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
733 ei.mgValue -= pos.can_castle(Us)? Sign[Us] * ((TrappedRookPenalty - mob * 16) / 2)
734 : Sign[Us] * (TrappedRookPenalty - mob * 16);
741 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
742 // and the type of attacked one.
745 void evaluate_threats(const Position& pos, EvalInfo& ei) {
747 const Color Them = (Us == WHITE ? BLACK : WHITE);
750 Value mgBonus = Value(0);
751 Value egBonus = Value(0);
753 // Enemy pieces not defended by a pawn and under our attack
754 Bitboard weakEnemies = pos.pieces_of_color(Them)
755 & ~ei.attackedBy[Them][PAWN]
756 & ei.attackedBy[Us][0];
760 // Add bonus according to type of attacked enemy pieces and to the
761 // type of attacking piece, from knights to queens. Kings are not
762 // considered because are already special handled in king evaluation.
763 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
765 b = ei.attackedBy[Us][pt1] & weakEnemies;
767 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
768 if (b & pos.pieces(pt2))
770 mgBonus += MidgameThreatBonus[pt1][pt2];
771 egBonus += EndgameThreatBonus[pt1][pt2];
774 ei.mgValue += Sign[Us] * mgBonus;
775 ei.egValue += Sign[Us] * egBonus;
779 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
780 // pieces of a given color.
782 template<Color Us, bool HasPopCnt>
783 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
785 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
786 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
787 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
788 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
790 // Sum up all attacked squares
791 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
792 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
793 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
797 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
799 template<Color Us, bool HasPopCnt>
800 void evaluate_king(const Position& pos, EvalInfo& ei) {
802 const Color Them = (Us == WHITE ? BLACK : WHITE);
803 const Square s = pos.king_square(Us);
807 if (relative_rank(Us, s) <= RANK_4)
809 shelter = ei.pi->get_king_shelter(pos, Us, s);
810 ei.mgValue += Sign[Us] * Value(shelter);
813 // King safety. This is quite complicated, and is almost certainly far
814 // from optimally tuned.
815 if ( pos.piece_count(Them, QUEEN) >= 1
816 && ei.kingAttackersCount[Them] >= 2
817 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
818 && ei.kingAdjacentZoneAttacksCount[Them])
820 // Is it the attackers turn to move?
821 bool sente = (Them == pos.side_to_move());
823 // Find the attacked squares around the king which has no defenders
824 // apart from the king itself
825 Bitboard undefended =
826 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
827 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
828 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
829 & ei.attacked_by(Us, KING);
831 Bitboard occ = pos.occupied_squares(), b, b2;
833 // Initialize the 'attackUnits' variable, which is used later on as an
834 // index to the SafetyTable[] array. The initial value is based on the
835 // number and types of the attacking pieces, the number of attacked and
836 // undefended squares around the king, the square of the king, and the
837 // quality of the pawn shelter.
839 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
840 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
841 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
843 // Analyse safe queen contact checks
844 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
847 Bitboard attackedByOthers =
848 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
849 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
851 b &= attackedByOthers;
854 // The bitboard b now contains the squares available for safe queen
856 int count = count_1s_max_15<HasPopCnt>(b);
857 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
859 // Is there a mate threat?
860 if (QueenContactMates && !pos.is_check())
862 Bitboard escapeSquares =
863 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
867 Square from, to = pop_1st_bit(&b);
868 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
870 // We have a mate, unless the queen is pinned or there
871 // is an X-ray attack through the queen.
872 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
874 from = pos.piece_list(Them, QUEEN, i);
875 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
876 && !bit_is_set(pos.pinned_pieces(Them), from)
877 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
878 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
880 ei.mateThreat[Them] = make_move(from, to);
888 // Analyse safe distance checks
889 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
891 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
894 b2 = b & ei.attacked_by(Them, QUEEN);
896 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
899 b2 = b & ei.attacked_by(Them, ROOK);
901 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
903 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
905 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
908 b2 = b & ei.attacked_by(Them, QUEEN);
910 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
913 b2 = b & ei.attacked_by(Them, BISHOP);
915 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
917 if (KnightCheckBonus > 0)
919 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
922 b2 = b & ei.attacked_by(Them, KNIGHT);
924 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
927 // Analyse discovered checks (only for non-pawns right now, consider
928 // adding pawns later).
929 if (DiscoveredCheckBonus)
931 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
933 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
936 // Has a mate threat been found? We don't do anything here if the
937 // side with the mating move is the side to move, because in that
938 // case the mating side will get a huge bonus at the end of the main
939 // evaluation function instead.
940 if (ei.mateThreat[Them] != MOVE_NONE)
941 attackUnits += MateThreatBonus;
943 // Ensure that attackUnits is between 0 and 99, in order to avoid array
944 // out of bounds errors:
948 if (attackUnits >= 100)
951 // Finally, extract the king safety score from the SafetyTable[] array.
952 // Add the score to the evaluation, and also to ei.futilityMargin. The
953 // reason for adding the king safety score to the futility margin is
954 // that the king safety scores can sometimes be very big, and that
955 // capturing a single attacking piece can therefore result in a score
956 // change far bigger than the value of the captured piece.
957 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[Us]);
959 ei.mgValue -= Sign[Us] * v;
961 if (Us == pos.side_to_move())
962 ei.futilityMargin += v;
967 // evaluate_passed_pawns() evaluates the passed pawns of the given color
970 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
972 const Color Them = (Us == WHITE ? BLACK : WHITE);
975 Square ourKingSq = pos.king_square(Us);
976 Square theirKingSq = pos.king_square(Them);
977 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
981 Square s = pop_1st_bit(&b);
983 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
984 assert(pos.pawn_is_passed(Us, s));
986 int r = int(relative_rank(Us, s) - RANK_2);
987 int tr = Max(0, r * (r - 1));
989 // Base bonus based on rank
990 Value mbonus = Value(20 * tr);
991 Value ebonus = Value(10 + r * r * 10);
993 // Adjust bonus based on king proximity
996 Square blockSq = s + pawn_push(Us);
998 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
999 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
1000 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
1002 // If the pawn is free to advance, increase bonus
1003 if (pos.square_is_empty(blockSq))
1005 // There are no enemy pawns in the pawn's path
1006 b2 = squares_in_front_of(Us, s);
1008 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
1010 // Squares attacked by us
1011 b4 = b2 & ei.attacked_by(Us);
1013 // Squares attacked or occupied by enemy pieces
1014 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
1016 // If there is an enemy rook or queen attacking the pawn from behind,
1017 // add all X-ray attacks by the rook or queen.
1018 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
1019 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
1022 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
1023 if (b3 == EmptyBoardBB)
1024 // No enemy attacks or pieces, huge bonus!
1025 // Even bigger if we protect the pawn's path
1026 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
1028 // OK, there are enemy attacks or pieces (but not pawns). Are those
1029 // squares which are attacked by the enemy also attacked by us ?
1030 // If yes, big bonus (but smaller than when there are no enemy attacks),
1031 // if no, somewhat smaller bonus.
1032 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
1034 // At last, add a small bonus when there are no *friendly* pieces
1035 // in the pawn's path.
1036 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
1037 ebonus += Value(tr);
1041 // If the pawn is supported by a friendly pawn, increase bonus
1042 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
1043 if (b2 & rank_bb(s))
1044 ebonus += Value(r * 20);
1045 else if (pos.attacks_from<PAWN>(s, Them) & b2)
1046 ebonus += Value(r * 12);
1048 // If the other side has only a king, check whether the pawn is
1050 if (pos.non_pawn_material(Them) == Value(0))
1055 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1056 d = square_distance(s, qsq)
1057 - square_distance(theirKingSq, qsq)
1058 + (Us != pos.side_to_move());
1062 int mtg = RANK_8 - relative_rank(Us, s);
1063 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1064 mtg += blockerCount;
1066 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1068 movesToGo[Us] = mtg;
1074 // Rook pawns are a special case: They are sometimes worse, and
1075 // sometimes better than other passed pawns. It is difficult to find
1076 // good rules for determining whether they are good or bad. For now,
1077 // we try the following: Increase the value for rook pawns if the
1078 // other side has no pieces apart from a knight, and decrease the
1079 // value if the other side has a rook or queen.
1080 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1082 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1083 && pos.piece_count(Them, KNIGHT) <= 1)
1084 ebonus += ebonus / 4;
1085 else if (pos.pieces(ROOK, QUEEN, Them))
1086 ebonus -= ebonus / 4;
1089 // Add the scores for this pawn to the middle game and endgame eval.
1090 ei.mgValue += apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame);
1091 ei.egValue += apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame);
1097 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1099 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1101 int movesToGo[2] = {0, 0};
1102 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1104 // Evaluate pawns for each color
1105 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1106 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1108 // Neither side has an unstoppable passed pawn?
1109 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1112 // Does only one side have an unstoppable passed pawn?
1113 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1115 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1116 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide]));
1119 { // Both sides have unstoppable pawns! Try to find out who queens
1120 // first. We begin by transforming 'movesToGo' to the number of
1121 // plies until the pawn queens for both sides.
1122 movesToGo[WHITE] *= 2;
1123 movesToGo[BLACK] *= 2;
1124 movesToGo[pos.side_to_move()]--;
1126 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1127 Color loserSide = opposite_color(winnerSide);
1129 // If one side queens at least three plies before the other, that side wins
1130 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1131 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1133 // If one side queens one ply before the other and checks the king or attacks
1134 // the undefended opponent's queening square, that side wins. To avoid cases
1135 // where the opponent's king could move somewhere before first pawn queens we
1136 // consider only free paths to queen for both pawns.
1137 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1138 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1140 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1142 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1143 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1145 Bitboard b = pos.occupied_squares();
1146 clear_bit(&b, pawnToGo[winnerSide]);
1147 clear_bit(&b, pawnToGo[loserSide]);
1148 b = queen_attacks_bb(winnerQSq, b);
1150 if ( (b & pos.pieces(KING, loserSide))
1151 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1152 ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1158 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1159 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1162 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1164 assert(square_is_ok(s));
1165 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1167 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1168 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1170 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1171 && pos.see(s, b6) < 0
1172 && pos.see(s, b8) < 0)
1174 ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
1175 ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
1180 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1181 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1182 // black), and assigns a penalty if it is. This pattern can obviously
1183 // only occur in Chess960 games.
1185 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1187 Piece pawn = piece_of_color_and_type(us, PAWN);
1191 assert(square_is_ok(s));
1192 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1194 if (square_file(s) == FILE_A)
1196 b2 = relative_square(us, SQ_B2);
1197 b3 = relative_square(us, SQ_B3);
1198 c3 = relative_square(us, SQ_C3);
1202 b2 = relative_square(us, SQ_G2);
1203 b3 = relative_square(us, SQ_G3);
1204 c3 = relative_square(us, SQ_F3);
1207 if (pos.piece_on(b2) == pawn)
1211 if (!pos.square_is_empty(b3))
1212 penalty = 2*TrappedBishopA1H1Penalty;
1213 else if (pos.piece_on(c3) == pawn)
1214 penalty = TrappedBishopA1H1Penalty;
1216 penalty = TrappedBishopA1H1Penalty / 2;
1218 ei.mgValue -= Sign[us] * penalty;
1219 ei.egValue -= Sign[us] * penalty;
1224 // evaluate_space() computes the space evaluation for a given side. The
1225 // space evaluation is a simple bonus based on the number of safe squares
1226 // available for minor pieces on the central four files on ranks 2--4. Safe
1227 // squares one, two or three squares behind a friendly pawn are counted
1228 // twice. Finally, the space bonus is scaled by a weight taken from the
1229 // material hash table.
1230 template<Color Us, bool HasPopCnt>
1231 void evaluate_space(const Position& pos, EvalInfo& ei) {
1233 const Color Them = (Us == WHITE ? BLACK : WHITE);
1235 // Find the safe squares for our pieces inside the area defined by
1236 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1237 // pawn, or if it is undefended and attacked by an enemy piece.
1239 Bitboard safeSquares = SpaceMask[Us]
1240 & ~pos.pieces(PAWN, Us)
1241 & ~ei.attacked_by(Them, PAWN)
1242 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1244 // Find all squares which are at most three squares behind some friendly
1246 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1247 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1248 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1250 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1251 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1253 ei.mgValue += Sign[Us] * apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
1257 // apply_weight() applies an evaluation weight to a value
1259 inline Value apply_weight(Value v, int w) {
1260 return (v*w) / 0x100;
1264 // scale_by_game_phase() interpolates between a middle game and an endgame
1265 // score, based on game phase. It also scales the return value by a
1266 // ScaleFactor array.
1268 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
1270 assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
1271 assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
1272 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1274 ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
1276 Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
1277 return Value(int(result) & ~(GrainSize - 1));
1281 // weight_option() computes the value of an evaluation weight, by combining
1282 // an UCI-configurable weight with an internal weight.
1284 int weight_option(const std::string& opt, int internalWeight) {
1286 int uciWeight = get_option_value_int(opt);
1287 uciWeight = (uciWeight * 0x100) / 100;
1288 return (uciWeight * internalWeight) / 0x100;
1292 // init_safety() initizes the king safety evaluation, based on UCI
1293 // parameters. It is called from read_weights().
1295 void init_safety() {
1297 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1298 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1299 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1300 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1301 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1302 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1303 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1305 int maxSlope = get_option_value_int("King Safety Max Slope");
1306 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1307 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1308 double b = get_option_value_int("King Safety X Intercept");
1309 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1310 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1312 for (int i = 0; i < 100; i++)
1315 SafetyTable[i] = Value(0);
1317 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1319 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1322 for (int i = 0; i < 100; i++)
1324 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1325 for (int j = i + 1; j < 100; j++)
1326 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1328 if (SafetyTable[i] > Value(peak))
1329 SafetyTable[i] = Value(peak);