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 Score WeightMobility, WeightPawnStructure;
50 Score WeightPassedPawns, WeightSpace;
51 Score WeightKingSafety[2];
53 // Internal evaluation weights. These are applied on top of the evaluation
54 // weights read from UCI parameters. The purpose is to be able to change
55 // the evaluation weights while keeping the default values of the UCI
56 // parameters at 100, which looks prettier.
58 // Values modified by Joona Kiiski
59 const Score WeightMobilityInternal = Score(248, 271);
60 const Score WeightPawnStructureInternal = Score(233, 201);
61 const Score WeightPassedPawnsInternal = Score(252, 259);
62 const Score WeightSpaceInternal = Score( 46, 0);
63 const Score WeightKingSafetyInternal = Score(247, 0);
64 const Score WeightKingOppSafetyInternal = Score(259, 0);
66 // Mobility and outposts bonus modified by Joona Kiiski
68 // Visually better to define tables constants
72 // Knight mobility bonus in middle game and endgame, indexed by the number
73 // of attacked squares not occupied by friendly piecess.
74 const Score KnightMobilityBonus[] = {
75 S(-38,-33), S(-25,-23), S(-12,-13), S( 0,-3),
76 S( 12, 7), S( 25, 17), S( 31, 22), S(38, 27), S(38, 27)
79 // Bishop mobility bonus in middle game and endgame, indexed by the number
80 // of attacked squares not occupied by friendly pieces. X-ray attacks through
81 // queens are also included.
82 const Score BishopMobilityBonus[] = {
83 S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12),
84 S( 31, 26), S( 45, 40), S(57, 52), S(65, 60),
85 S( 71, 65), S( 74, 69), S(76, 71), S(78, 73),
86 S( 79, 74), S( 80, 75), S(81, 76), S(81, 76)
89 // Rook mobility bonus in middle game and endgame, indexed by the number
90 // of attacked squares not occupied by friendly pieces. X-ray attacks through
91 // queens and rooks are also included.
92 const Score RookMobilityBonus[] = {
93 S(-20,-36), S(-14,-19), S(-8, -3), S(-2, 13),
94 S( 4, 29), S( 10, 46), S(14, 62), S(19, 79),
95 S( 23, 95), S( 26,106), S(27,111), S(28,114),
96 S( 29,116), S( 30,117), S(31,118), S(32,118)
99 // Queen mobility bonus in middle game and endgame, indexed by the number
100 // of attacked squares not occupied by friendly pieces.
101 const Score QueenMobilityBonus[] = {
102 S(-10,-18), S(-8,-13), S(-6, -7), S(-3, -2), S(-1, 3), S( 1, 8),
103 S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
104 S( 16, 35), S(17, 35), S(18, 35), S(20, 35), S(20, 35), S(20, 35),
105 S( 20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
106 S( 20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
107 S( 20, 35), S(20, 35)
110 // Pointers table to access mobility tables through piece type
111 const Score* MobilityBonus[] = { 0, 0, KnightMobilityBonus, BishopMobilityBonus, RookMobilityBonus, QueenMobilityBonus };
113 // Outpost bonuses for knights and bishops, indexed by square (from white's
115 const Value KnightOutpostBonus[64] = {
117 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
118 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
119 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
120 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
121 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
122 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
123 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
124 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
127 const Value BishopOutpostBonus[64] = {
129 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
130 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
131 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
132 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
133 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
134 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
135 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
136 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
139 // Bonus for unstoppable passed pawns
140 const Value UnstoppablePawnValue = Value(0x500);
142 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
143 const Score RookOn7thBonus = Score(47, 98);
144 const Score QueenOn7thBonus = Score(27, 54);
146 // Rooks on open files (modified by Joona Kiiski)
147 const Score RookOpenFileBonus = Score(43, 43);
148 const Score RookHalfOpenFileBonus = Score(19, 19);
150 // Penalty for rooks trapped inside a friendly king which has lost the
152 const Value TrappedRookPenalty = Value(180);
154 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
156 const Score TrappedBishopA7H7Penalty = Score(300, 300);
158 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
159 const Bitboard MaskA7H7[2] = {
160 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
161 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
164 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
165 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
166 // happen in Chess960 games.
167 const Score TrappedBishopA1H1Penalty = Score(100, 100);
169 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
170 const Bitboard MaskA1H1[2] = {
171 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
172 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
175 // The SpaceMask[color] contains the area of the board which is considered
176 // by the space evaluation. In the middle game, each side is given a bonus
177 // based on how many squares inside this area are safe and available for
178 // friendly minor pieces.
179 const Bitboard SpaceMask[2] = {
180 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
181 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
182 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
183 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
184 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
185 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
188 /// King safety constants and variables. The king safety scores are taken
189 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
190 /// the strength of the attack are added up into an integer, which is used
191 /// as an index to SafetyTable[].
193 // Attack weights for each piece type and table indexed on piece type
194 const int QueenAttackWeight = 5;
195 const int RookAttackWeight = 3;
196 const int BishopAttackWeight = 2;
197 const int KnightAttackWeight = 2;
199 const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
201 // Bonuses for safe checks, initialized from UCI options
202 int QueenContactCheckBonus, DiscoveredCheckBonus;
203 int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
205 // Scan for queen contact mates?
206 const bool QueenContactMates = true;
208 // Bonus for having a mate threat, initialized from UCI options
211 // ThreatBonus[][] contains bonus according to which piece type
212 // attacks which one.
213 #define Z Score(0, 0)
215 const Score ThreatBonus[8][8] = {
216 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
217 { Z, S(18,37), Z, S(37,47), S(55,97), S(55,97), Z, Z }, // KNIGHT attacks
218 { Z, S(18,37), S(37,47), Z, S(55,97), S(55,97), Z, Z }, // BISHOP attacks
219 { Z, S( 9,27), S(27,47), S(27,47), Z, S(37,47), Z, Z }, // ROOK attacks
220 { Z, S(27,37), S(27,37), S(27,37), S(27,37), Z, Z, Z }, // QUEEN attacks
221 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
222 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
223 { Z, Z, Z, Z, Z, Z, Z, Z } // not used
226 // ThreatedByPawnPenalty[] contains a penalty according to which piece
227 // type is attacked by an enemy pawn.
228 const Score ThreatedByPawnPenalty[8] = {
229 Z, Z, S(56, 70), S(56, 70), S(76, 99), S(86, 118), Z, Z
234 // InitKingDanger[] contains bonuses based on the position of the defending
236 const int InitKingDanger[64] = {
237 2, 0, 2, 5, 5, 2, 0, 2,
238 2, 2, 4, 8, 8, 4, 2, 2,
239 7, 10, 12, 12, 12, 12, 10, 7,
240 15, 15, 15, 15, 15, 15, 15, 15,
241 15, 15, 15, 15, 15, 15, 15, 15,
242 15, 15, 15, 15, 15, 15, 15, 15,
243 15, 15, 15, 15, 15, 15, 15, 15,
244 15, 15, 15, 15, 15, 15, 15, 15
247 // SafetyTable[] contains the actual king safety scores. It is initialized
249 Value SafetyTable[100];
251 // Pawn and material hash tables, indexed by the current thread id
252 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
253 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
255 // Sizes of pawn and material hash tables
256 const int PawnTableSize = 16384;
257 const int MaterialTableSize = 1024;
259 // Function prototypes
260 template<bool HasPopCnt>
261 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
263 template<Color Us, bool HasPopCnt>
264 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
266 template<Color Us, bool HasPopCnt>
267 void evaluate_king(const Position& pos, EvalInfo& ei);
270 void evaluate_threats(const Position& pos, EvalInfo& ei);
272 template<Color Us, bool HasPopCnt>
273 void evaluate_space(const Position& pos, EvalInfo& ei);
275 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
276 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
277 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
278 inline Score apply_weight(Score v, Score weight);
279 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
280 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
289 /// evaluate() is the main evaluation function. It always computes two
290 /// values, an endgame score and a middle game score, and interpolates
291 /// between them based on the remaining material.
292 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
294 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
295 : do_evaluate<false>(pos, ei, threadID);
300 template<bool HasPopCnt>
301 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
304 assert(threadID >= 0 && threadID < THREAD_MAX);
305 assert(!pos.is_check());
307 memset(&ei, 0, sizeof(EvalInfo));
309 // Initialize by reading the incrementally updated scores included in the
310 // position object (material + piece square tables)
311 ei.value = pos.value();
313 // Probe the material hash table
314 ei.mi = MaterialTable[threadID]->get_material_info(pos);
315 ei.value += ei.mi->material_value();
317 // If we have a specialized evaluation function for the current material
318 // configuration, call it and return
319 if (ei.mi->specialized_eval_exists())
320 return ei.mi->evaluate(pos);
322 // After get_material_info() call that modifies them
323 ScaleFactor factor[2];
324 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
325 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
327 // Probe the pawn hash table
328 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
329 ei.value += apply_weight(ei.pi->value(), WeightPawnStructure);
331 // Initialize king attack bitboards and king attack zones for both sides
332 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
333 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
334 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
335 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
337 // Initialize pawn attack bitboards for both sides
338 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
339 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
340 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
341 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
343 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
346 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
349 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
350 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
352 // Kings. Kings are evaluated after all other pieces for both sides,
353 // because we need complete attack information for all pieces when computing
354 // the king safety evaluation.
355 evaluate_king<WHITE, HasPopCnt>(pos, ei);
356 evaluate_king<BLACK, HasPopCnt>(pos, ei);
358 // Evaluate tactical threats, we need full attack info
359 evaluate_threats<WHITE>(pos, ei);
360 evaluate_threats<BLACK>(pos, ei);
362 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
363 // because we need to know which side promotes first in positions where
364 // both sides have an unstoppable passed pawn. To be called after all attacks
365 // are computed, included king.
366 if (ei.pi->passed_pawns())
367 evaluate_passed_pawns(pos, ei);
369 Phase phase = pos.game_phase();
371 // Middle-game specific evaluation terms
372 if (phase > PHASE_ENDGAME)
374 // Pawn storms in positions with opposite castling.
375 if ( square_file(pos.king_square(WHITE)) >= FILE_E
376 && square_file(pos.king_square(BLACK)) <= FILE_D)
378 ei.value += Score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
380 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
381 && square_file(pos.king_square(BLACK)) >= FILE_E)
383 ei.value += Score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
385 // Evaluate space for both sides
386 if (ei.mi->space_weight() > 0)
388 evaluate_space<WHITE, HasPopCnt>(pos, ei);
389 evaluate_space<BLACK, HasPopCnt>(pos, ei);
394 ei.value += apply_weight(ei.mobility, WeightMobility);
396 // If we don't already have an unusual scale factor, check for opposite
397 // colored bishop endgames, and use a lower scale for those
398 if ( phase < PHASE_MIDGAME
399 && pos.opposite_colored_bishops()
400 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.value.eg() > Value(0))
401 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.value.eg() < Value(0))))
405 // Only the two bishops ?
406 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
407 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
409 // Check for KBP vs KB with only a single pawn that is almost
410 // certainly a draw or at least two pawns.
411 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
412 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
415 // Endgame with opposite-colored bishops, but also other pieces. Still
416 // a bit drawish, but not as drawish as with only the two bishops.
417 sf = ScaleFactor(50);
419 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
421 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
425 // Interpolate between the middle game and the endgame score
426 Color stm = pos.side_to_move();
428 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
430 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
435 /// quick_evaluate() does a very approximate evaluation of the current position.
436 /// It currently considers only material and piece square table scores. Perhaps
437 /// we should add scores from the pawn and material hash tables?
439 Value quick_evaluate(const Position &pos) {
444 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
446 Phase ph = pos.game_phase();
447 Color stm = pos.side_to_move();
449 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
453 /// init_eval() initializes various tables used by the evaluation function
455 void init_eval(int threads) {
457 assert(threads <= THREAD_MAX);
459 for (int i = 0; i < THREAD_MAX; i++)
464 delete MaterialTable[i];
466 MaterialTable[i] = NULL;
470 PawnTable[i] = new PawnInfoTable(PawnTableSize);
471 if (!MaterialTable[i])
472 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
477 /// quit_eval() releases heap-allocated memory at program termination
481 for (int i = 0; i < THREAD_MAX; i++)
484 delete MaterialTable[i];
486 MaterialTable[i] = NULL;
491 /// read_weights() reads evaluation weights from the corresponding UCI parameters
493 void read_weights(Color us) {
495 Color them = opposite_color(us);
497 WeightMobility = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightMobilityInternal);
498 WeightPawnStructure = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightPawnStructureInternal);
499 WeightPassedPawns = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightPassedPawnsInternal);
500 WeightSpace = weight_option("Space", "Space", WeightSpaceInternal);
501 WeightKingSafety[us] = weight_option("Cowardice", "Cowardice", WeightKingSafetyInternal);
502 WeightKingSafety[them] = weight_option("Aggressiveness", "Aggressiveness", WeightKingOppSafetyInternal);
504 // If running in analysis mode, make sure we use symmetrical king safety. We do this
505 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
506 if (get_option_value_bool("UCI_AnalyseMode"))
508 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
509 WeightKingSafety[them] = WeightKingSafety[us];
517 // evaluate_mobility() computes mobility and attacks for every piece
519 template<PieceType Piece, Color Us, bool HasPopCnt>
520 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
522 const Color Them = (Us == WHITE ? BLACK : WHITE);
524 // Update attack info
525 ei.attackedBy[Us][Piece] |= b;
528 if (b & ei.kingZone[Us])
530 ei.kingAttackersCount[Us]++;
531 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
532 Bitboard bb = (b & ei.attackedBy[Them][KING]);
534 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
538 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
539 : count_1s<HasPopCnt>(b & mob_area));
541 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
546 // evaluate_outposts() evaluates bishop and knight outposts squares
548 template<PieceType Piece, Color Us>
549 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
551 const Color Them = (Us == WHITE ? BLACK : WHITE);
553 // Initial bonus based on square
554 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
555 : KnightOutpostBonus[relative_square(Us, s)]);
557 // Increase bonus if supported by pawn, especially if the opponent has
558 // no minor piece which can exchange the outpost piece
559 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
561 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
562 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
563 bonus += bonus + bonus / 2;
567 ei.value += Sign[Us] * Score(bonus, bonus);
571 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
573 template<PieceType Piece, Color Us, bool HasPopCnt>
574 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
581 const Color Them = (Us == WHITE ? BLACK : WHITE);
582 const Square* ptr = pos.piece_list_begin(Us, Piece);
584 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
585 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
587 while ((s = *ptr++) != SQ_NONE)
589 if (Piece == KNIGHT || Piece == QUEEN)
590 b = pos.attacks_from<Piece>(s);
591 else if (Piece == BISHOP)
592 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
593 else if (Piece == ROOK)
594 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
598 // Attacks and mobility
599 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
601 // Decrease score if we are attacked by an enemy pawn. Remaining part
602 // of threat evaluation must be done later when we have full attack info.
603 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
604 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
606 // Bishop and knight outposts squares
607 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
608 evaluate_outposts<Piece, Us>(pos, ei, s);
610 // Special patterns: trapped bishops on a7/h7/a2/h2
611 // and trapped bishops on a1/h1/a8/h8 in Chess960.
614 if (bit_is_set(MaskA7H7[Us], s))
615 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
617 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
618 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
621 if (Piece == ROOK || Piece == QUEEN)
623 // Queen or rook on 7th rank
624 if ( relative_rank(Us, s) == RANK_7
625 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
627 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
631 // Special extra evaluation for rooks
634 // Open and half-open files
636 if (ei.pi->file_is_half_open(Us, f))
638 if (ei.pi->file_is_half_open(Them, f))
639 ei.value += Sign[Us] * RookOpenFileBonus;
641 ei.value += Sign[Us] * RookHalfOpenFileBonus;
644 // Penalize rooks which are trapped inside a king. Penalize more if
645 // king has lost right to castle.
646 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
649 ksq = pos.king_square(Us);
651 if ( square_file(ksq) >= FILE_E
652 && square_file(s) > square_file(ksq)
653 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
655 // Is there a half-open file between the king and the edge of the board?
656 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
657 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
658 : (TrappedRookPenalty - mob * 16), 0);
660 else if ( square_file(ksq) <= FILE_D
661 && square_file(s) < square_file(ksq)
662 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
664 // Is there a half-open file between the king and the edge of the board?
665 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
666 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
667 : (TrappedRookPenalty - mob * 16), 0);
674 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
675 // and the type of attacked one.
678 void evaluate_threats(const Position& pos, EvalInfo& ei) {
680 const Color Them = (Us == WHITE ? BLACK : WHITE);
685 // Enemy pieces not defended by a pawn and under our attack
686 Bitboard weakEnemies = pos.pieces_of_color(Them)
687 & ~ei.attackedBy[Them][PAWN]
688 & ei.attackedBy[Us][0];
692 // Add bonus according to type of attacked enemy pieces and to the
693 // type of attacking piece, from knights to queens. Kings are not
694 // considered because are already special handled in king evaluation.
695 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
697 b = ei.attackedBy[Us][pt1] & weakEnemies;
699 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
700 if (b & pos.pieces(pt2))
701 bonus += ThreatBonus[pt1][pt2];
703 ei.value += Sign[Us] * bonus;
707 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
708 // pieces of a given color.
710 template<Color Us, bool HasPopCnt>
711 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
713 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
714 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
715 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
716 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
718 // Sum up all attacked squares
719 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
720 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
721 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
725 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
727 template<Color Us, bool HasPopCnt>
728 void evaluate_king(const Position& pos, EvalInfo& ei) {
730 const Color Them = (Us == WHITE ? BLACK : WHITE);
731 const Square s = pos.king_square(Us);
735 if (relative_rank(Us, s) <= RANK_4)
737 shelter = ei.pi->get_king_shelter(pos, Us, s);
738 ei.value += Sign[Us] * Score(shelter, 0);
741 // King safety. This is quite complicated, and is almost certainly far
742 // from optimally tuned.
743 if ( pos.piece_count(Them, QUEEN) >= 1
744 && ei.kingAttackersCount[Them] >= 2
745 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
746 && ei.kingAdjacentZoneAttacksCount[Them])
748 // Is it the attackers turn to move?
749 bool sente = (Them == pos.side_to_move());
751 // Find the attacked squares around the king which has no defenders
752 // apart from the king itself
753 Bitboard undefended =
754 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
755 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
756 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
757 & ei.attacked_by(Us, KING);
759 Bitboard occ = pos.occupied_squares(), b, b2;
761 // Initialize the 'attackUnits' variable, which is used later on as an
762 // index to the SafetyTable[] array. The initial value is based on the
763 // number and types of the attacking pieces, the number of attacked and
764 // undefended squares around the king, the square of the king, and the
765 // quality of the pawn shelter.
767 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
768 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
769 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
771 // Analyse safe queen contact checks
772 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
775 Bitboard attackedByOthers =
776 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
777 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
779 b &= attackedByOthers;
782 // The bitboard b now contains the squares available for safe queen
784 int count = count_1s_max_15<HasPopCnt>(b);
785 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
787 // Is there a mate threat?
788 if (QueenContactMates && !pos.is_check())
790 Bitboard escapeSquares =
791 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
795 Square from, to = pop_1st_bit(&b);
796 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
798 // We have a mate, unless the queen is pinned or there
799 // is an X-ray attack through the queen.
800 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
802 from = pos.piece_list(Them, QUEEN, i);
803 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
804 && !bit_is_set(pos.pinned_pieces(Them), from)
805 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
806 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
808 ei.mateThreat[Them] = make_move(from, to);
816 // Analyse safe distance checks
817 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
819 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
822 b2 = b & ei.attacked_by(Them, QUEEN);
824 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
827 b2 = b & ei.attacked_by(Them, ROOK);
829 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
831 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
833 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
836 b2 = b & ei.attacked_by(Them, QUEEN);
838 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
841 b2 = b & ei.attacked_by(Them, BISHOP);
843 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
845 if (KnightCheckBonus > 0)
847 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
850 b2 = b & ei.attacked_by(Them, KNIGHT);
852 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
855 // Analyse discovered checks (only for non-pawns right now, consider
856 // adding pawns later).
857 if (DiscoveredCheckBonus)
859 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
861 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
864 // Has a mate threat been found? We don't do anything here if the
865 // side with the mating move is the side to move, because in that
866 // case the mating side will get a huge bonus at the end of the main
867 // evaluation function instead.
868 if (ei.mateThreat[Them] != MOVE_NONE)
869 attackUnits += MateThreatBonus;
871 // Ensure that attackUnits is between 0 and 99, in order to avoid array
872 // out of bounds errors:
876 if (attackUnits >= 100)
879 // Finally, extract the king safety score from the SafetyTable[] array.
880 // Add the score to the evaluation, and also to ei.futilityMargin. The
881 // reason for adding the king safety score to the futility margin is
882 // that the king safety scores can sometimes be very big, and that
883 // capturing a single attacking piece can therefore result in a score
884 // change far bigger than the value of the captured piece.
885 Score v = apply_weight(Score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
887 ei.value -= Sign[Us] * v;
889 if (Us == pos.side_to_move())
890 ei.futilityMargin += v.mg();
895 // evaluate_passed_pawns() evaluates the passed pawns of the given color
898 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
900 const Color Them = (Us == WHITE ? BLACK : WHITE);
903 Square ourKingSq = pos.king_square(Us);
904 Square theirKingSq = pos.king_square(Them);
905 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
909 Square s = pop_1st_bit(&b);
911 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
912 assert(pos.pawn_is_passed(Us, s));
914 int r = int(relative_rank(Us, s) - RANK_2);
915 int tr = Max(0, r * (r - 1));
917 // Base bonus based on rank
918 Value mbonus = Value(20 * tr);
919 Value ebonus = Value(10 + r * r * 10);
921 // Adjust bonus based on king proximity
924 Square blockSq = s + pawn_push(Us);
926 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
927 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
928 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
930 // If the pawn is free to advance, increase bonus
931 if (pos.square_is_empty(blockSq))
933 // There are no enemy pawns in the pawn's path
934 b2 = squares_in_front_of(Us, s);
936 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
938 // Squares attacked by us
939 b4 = b2 & ei.attacked_by(Us);
941 // Squares attacked or occupied by enemy pieces
942 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
944 // If there is an enemy rook or queen attacking the pawn from behind,
945 // add all X-ray attacks by the rook or queen.
946 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
947 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
950 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
951 if (b3 == EmptyBoardBB)
952 // No enemy attacks or pieces, huge bonus!
953 // Even bigger if we protect the pawn's path
954 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
956 // OK, there are enemy attacks or pieces (but not pawns). Are those
957 // squares which are attacked by the enemy also attacked by us ?
958 // If yes, big bonus (but smaller than when there are no enemy attacks),
959 // if no, somewhat smaller bonus.
960 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
962 // At last, add a small bonus when there are no *friendly* pieces
963 // in the pawn's path.
964 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
969 // If the pawn is supported by a friendly pawn, increase bonus
970 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
972 ebonus += Value(r * 20);
973 else if (pos.attacks_from<PAWN>(s, Them) & b2)
974 ebonus += Value(r * 12);
976 // If the other side has only a king, check whether the pawn is
978 if (pos.non_pawn_material(Them) == Value(0))
983 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
984 d = square_distance(s, qsq)
985 - square_distance(theirKingSq, qsq)
986 + (Us != pos.side_to_move());
990 int mtg = RANK_8 - relative_rank(Us, s);
991 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
994 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1002 // Rook pawns are a special case: They are sometimes worse, and
1003 // sometimes better than other passed pawns. It is difficult to find
1004 // good rules for determining whether they are good or bad. For now,
1005 // we try the following: Increase the value for rook pawns if the
1006 // other side has no pieces apart from a knight, and decrease the
1007 // value if the other side has a rook or queen.
1008 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1010 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1011 && pos.piece_count(Them, KNIGHT) <= 1)
1012 ebonus += ebonus / 4;
1013 else if (pos.pieces(ROOK, QUEEN, Them))
1014 ebonus -= ebonus / 4;
1017 // Add the scores for this pawn to the middle game and endgame eval.
1018 ei.value += Sign[Us] * apply_weight(Score(mbonus, ebonus), WeightPassedPawns);
1024 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1026 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1028 int movesToGo[2] = {0, 0};
1029 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1031 // Evaluate pawns for each color
1032 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1033 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1035 // Neither side has an unstoppable passed pawn?
1036 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1039 // Does only one side have an unstoppable passed pawn?
1040 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1042 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1043 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1046 { // Both sides have unstoppable pawns! Try to find out who queens
1047 // first. We begin by transforming 'movesToGo' to the number of
1048 // plies until the pawn queens for both sides.
1049 movesToGo[WHITE] *= 2;
1050 movesToGo[BLACK] *= 2;
1051 movesToGo[pos.side_to_move()]--;
1053 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1054 Color loserSide = opposite_color(winnerSide);
1056 // If one side queens at least three plies before the other, that side wins
1057 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1058 ei.value += Sign[winnerSide] * Score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1060 // If one side queens one ply before the other and checks the king or attacks
1061 // the undefended opponent's queening square, that side wins. To avoid cases
1062 // where the opponent's king could move somewhere before first pawn queens we
1063 // consider only free paths to queen for both pawns.
1064 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1065 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1067 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1069 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1070 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1072 Bitboard b = pos.occupied_squares();
1073 clear_bit(&b, pawnToGo[winnerSide]);
1074 clear_bit(&b, pawnToGo[loserSide]);
1075 b = queen_attacks_bb(winnerQSq, b);
1077 if ( (b & pos.pieces(KING, loserSide))
1078 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1079 ei.value += Sign[winnerSide] * Score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1085 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1086 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1089 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1091 assert(square_is_ok(s));
1092 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1094 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1095 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1097 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1098 && pos.see(s, b6) < 0
1099 && pos.see(s, b8) < 0)
1101 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1106 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1107 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1108 // black), and assigns a penalty if it is. This pattern can obviously
1109 // only occur in Chess960 games.
1111 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1113 Piece pawn = piece_of_color_and_type(us, PAWN);
1117 assert(square_is_ok(s));
1118 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1120 if (square_file(s) == FILE_A)
1122 b2 = relative_square(us, SQ_B2);
1123 b3 = relative_square(us, SQ_B3);
1124 c3 = relative_square(us, SQ_C3);
1128 b2 = relative_square(us, SQ_G2);
1129 b3 = relative_square(us, SQ_G3);
1130 c3 = relative_square(us, SQ_F3);
1133 if (pos.piece_on(b2) == pawn)
1137 if (!pos.square_is_empty(b3))
1138 penalty = 2 * TrappedBishopA1H1Penalty;
1139 else if (pos.piece_on(c3) == pawn)
1140 penalty = TrappedBishopA1H1Penalty;
1142 penalty = TrappedBishopA1H1Penalty / 2;
1144 ei.value -= Sign[us] * penalty;
1149 // evaluate_space() computes the space evaluation for a given side. The
1150 // space evaluation is a simple bonus based on the number of safe squares
1151 // available for minor pieces on the central four files on ranks 2--4. Safe
1152 // squares one, two or three squares behind a friendly pawn are counted
1153 // twice. Finally, the space bonus is scaled by a weight taken from the
1154 // material hash table.
1155 template<Color Us, bool HasPopCnt>
1156 void evaluate_space(const Position& pos, EvalInfo& ei) {
1158 const Color Them = (Us == WHITE ? BLACK : WHITE);
1160 // Find the safe squares for our pieces inside the area defined by
1161 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1162 // pawn, or if it is undefended and attacked by an enemy piece.
1164 Bitboard safeSquares = SpaceMask[Us]
1165 & ~pos.pieces(PAWN, Us)
1166 & ~ei.attacked_by(Them, PAWN)
1167 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1169 // Find all squares which are at most three squares behind some friendly
1171 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1172 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1173 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1175 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1176 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1178 ei.value += Sign[Us] * apply_weight(Score(space * ei.mi->space_weight(), 0), WeightSpace);
1182 // apply_weight() applies an evaluation weight to a value
1184 inline Score apply_weight(Score v, Score w) {
1185 return v * w / 0x100;
1189 // scale_by_game_phase() interpolates between a middle game and an endgame
1190 // score, based on game phase. It also scales the return value by a
1191 // ScaleFactor array.
1193 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1195 assert(v.mg() > -VALUE_INFINITE && v.mg() < VALUE_INFINITE);
1196 assert(v.eg() > -VALUE_INFINITE && v.eg() < VALUE_INFINITE);
1197 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1199 Value ev = apply_scale_factor(v.eg(), sf[(v.eg() > Value(0) ? WHITE : BLACK)]);
1201 Value result = Value(int((v.mg() * ph + ev * (128 - ph)) / 128));
1202 return Value(int(result) & ~(GrainSize - 1));
1206 // weight_option() computes the value of an evaluation weight, by combining
1207 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1209 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1211 Score uciWeight(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1212 uciWeight = (uciWeight * 0x100) / 100;
1213 return (uciWeight * internalWeight) / 0x100;
1217 // init_safety() initizes the king safety evaluation, based on UCI
1218 // parameters. It is called from read_weights().
1220 void init_safety() {
1222 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1223 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1224 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1225 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1226 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1227 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1228 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1230 int maxSlope = get_option_value_int("King Safety Max Slope");
1231 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1232 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1233 double b = get_option_value_int("King Safety X Intercept");
1234 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1235 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1237 for (int i = 0; i < 100; i++)
1240 SafetyTable[i] = Value(0);
1242 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1244 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1247 for (int i = 0; i < 100; i++)
1249 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1250 for (int j = i + 1; j < 100; j++)
1251 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1253 if (SafetyTable[i] > Value(peak))
1254 SafetyTable[i] = Value(peak);
1259 std::ostream& operator<<(std::ostream &os, Score s) {
1261 return os << "(" << s.mg() << ", " << s.eg() << ")";