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 = make_score(248, 271);
60 const Score WeightPawnStructureInternal = make_score(233, 201);
61 const Score WeightPassedPawnsInternal = make_score(252, 259);
62 const Score WeightSpaceInternal = make_score( 46, 0);
63 const Score WeightKingSafetyInternal = make_score(247, 0);
64 const Score WeightKingOppSafetyInternal = make_score(259, 0);
66 // Mobility and outposts bonus modified by Joona Kiiski
69 #define S(mg, eg) make_score(mg, eg)
73 // Knight mobility bonus in middle game and endgame, indexed by the number
74 // of attacked squares not occupied by friendly piecess.
75 const Score KnightMobilityBonus[16] = {
76 S(-38,-33), S(-25,-23), S(-12,-13), S( 0,-3),
77 S( 12, 7), S( 25, 17), S( 31, 22), S(38, 27), S(38, 27)
80 // Bishop mobility bonus in middle game and endgame, indexed by the number
81 // of attacked squares not occupied by friendly pieces. X-ray attacks through
82 // queens are also included.
83 const Score BishopMobilityBonus[16] = {
84 S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12),
85 S( 31, 26), S( 45, 40), S(57, 52), S(65, 60),
86 S( 71, 65), S( 74, 69), S(76, 71), S(78, 73),
87 S( 79, 74), S( 80, 75), S(81, 76), S(81, 76)
90 // Rook mobility bonus in middle game and endgame, indexed by the number
91 // of attacked squares not occupied by friendly pieces. X-ray attacks through
92 // queens and rooks are also included.
93 const Score RookMobilityBonus[16] = {
94 S(-20,-36), S(-14,-19), S(-8, -3), S(-2, 13),
95 S( 4, 29), S( 10, 46), S(14, 62), S(19, 79),
96 S( 23, 95), S( 26,106), S(27,111), S(28,114),
97 S( 29,116), S( 30,117), S(31,118), S(32,118)
100 // Queen mobility bonus in middle game and endgame, indexed by the number
101 // of attacked squares not occupied by friendly pieces.
102 const Score QueenMobilityBonus[32] = {
103 S(-10,-18), S(-8,-13), S(-6, -7), S(-3, -2), S(-1, 3), S( 1, 8),
104 S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
105 S( 16, 35), S(17, 35), S(18, 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), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
108 S( 20, 35), S(20, 35)
111 // Pointers table to access mobility tables through piece type
112 const Score* MobilityBonus[8] = { 0, 0, KnightMobilityBonus, BishopMobilityBonus,
113 RookMobilityBonus, QueenMobilityBonus, 0, 0 };
115 // Outpost bonuses for knights and bishops, indexed by square (from white's
117 const Value KnightOutpostBonus[64] = {
119 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
120 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
121 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
122 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
123 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
124 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
125 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
126 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
129 const Value BishopOutpostBonus[64] = {
131 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
132 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
133 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
134 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
135 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
136 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
137 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
138 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
141 // ThreatBonus[][] contains bonus according to which piece type
142 // attacks which one.
145 const Score ThreatBonus[8][8] = {
146 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
147 { Z, S(18,37), Z, S(37,47), S(55,97), S(55,97), Z, Z }, // KNIGHT attacks
148 { Z, S(18,37), S(37,47), Z, S(55,97), S(55,97), Z, Z }, // BISHOP attacks
149 { Z, S( 9,27), S(27,47), S(27,47), Z, S(37,47), Z, Z }, // ROOK attacks
150 { Z, S(27,37), S(27,37), S(27,37), S(27,37), Z, Z, Z }, // QUEEN attacks
151 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
152 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
153 { Z, Z, Z, Z, Z, Z, Z, Z } // not used
156 // ThreatedByPawnPenalty[] contains a penalty according to which piece
157 // type is attacked by an enemy pawn.
158 const Score ThreatedByPawnPenalty[8] = {
159 Z, Z, S(56, 70), S(56, 70), S(76, 99), S(86, 118), Z, Z
165 // Bonus for unstoppable passed pawns
166 const Value UnstoppablePawnValue = Value(0x500);
168 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
169 const Score RookOn7thBonus = make_score(47, 98);
170 const Score QueenOn7thBonus = make_score(27, 54);
172 // Rooks on open files (modified by Joona Kiiski)
173 const Score RookOpenFileBonus = make_score(43, 43);
174 const Score RookHalfOpenFileBonus = make_score(19, 19);
176 // Penalty for rooks trapped inside a friendly king which has lost the
178 const Value TrappedRookPenalty = Value(180);
180 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
182 const Score TrappedBishopA7H7Penalty = make_score(300, 300);
184 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
185 const Bitboard MaskA7H7[2] = {
186 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
187 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
190 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
191 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
192 // happen in Chess960 games.
193 const Score TrappedBishopA1H1Penalty = make_score(100, 100);
195 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
196 const Bitboard MaskA1H1[2] = {
197 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
198 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
201 // The SpaceMask[color] contains the area of the board which is considered
202 // by the space evaluation. In the middle game, each side is given a bonus
203 // based on how many squares inside this area are safe and available for
204 // friendly minor pieces.
205 const Bitboard SpaceMask[2] = {
206 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
207 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
208 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
209 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
210 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
211 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
214 /// King safety constants and variables. The king safety scores are taken
215 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
216 /// the strength of the attack are added up into an integer, which is used
217 /// as an index to SafetyTable[].
219 // Attack weights for each piece type and table indexed on piece type
220 const int QueenAttackWeight = 5;
221 const int RookAttackWeight = 3;
222 const int BishopAttackWeight = 2;
223 const int KnightAttackWeight = 2;
225 const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
227 // Bonuses for safe checks, initialized from UCI options
228 int QueenContactCheckBonus, DiscoveredCheckBonus;
229 int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
231 // Scan for queen contact mates?
232 const bool QueenContactMates = true;
234 // Bonus for having a mate threat, initialized from UCI options
237 // InitKingDanger[] contains bonuses based on the position of the defending
239 const int InitKingDanger[64] = {
240 2, 0, 2, 5, 5, 2, 0, 2,
241 2, 2, 4, 8, 8, 4, 2, 2,
242 7, 10, 12, 12, 12, 12, 10, 7,
243 15, 15, 15, 15, 15, 15, 15, 15,
244 15, 15, 15, 15, 15, 15, 15, 15,
245 15, 15, 15, 15, 15, 15, 15, 15,
246 15, 15, 15, 15, 15, 15, 15, 15,
247 15, 15, 15, 15, 15, 15, 15, 15
250 // SafetyTable[] contains the actual king safety scores. It is initialized
252 Value SafetyTable[100];
254 // Pawn and material hash tables, indexed by the current thread id
255 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
256 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
258 // Sizes of pawn and material hash tables
259 const int PawnTableSize = 16384;
260 const int MaterialTableSize = 1024;
262 // Function prototypes
263 template<bool HasPopCnt>
264 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
266 template<Color Us, bool HasPopCnt>
267 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
269 template<Color Us, bool HasPopCnt>
270 void evaluate_king(const Position& pos, EvalInfo& ei);
273 void evaluate_threats(const Position& pos, EvalInfo& ei);
275 template<Color Us, bool HasPopCnt>
276 void evaluate_space(const Position& pos, EvalInfo& ei);
278 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
279 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
280 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
281 inline Score apply_weight(Score v, Score weight);
282 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
283 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
292 /// evaluate() is the main evaluation function. It always computes two
293 /// values, an endgame score and a middle game score, and interpolates
294 /// between them based on the remaining material.
295 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
297 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
298 : do_evaluate<false>(pos, ei, threadID);
303 template<bool HasPopCnt>
304 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
307 assert(threadID >= 0 && threadID < THREAD_MAX);
308 assert(!pos.is_check());
310 memset(&ei, 0, sizeof(EvalInfo));
312 // Initialize by reading the incrementally updated scores included in the
313 // position object (material + piece square tables)
314 ei.value = pos.value();
316 // Probe the material hash table
317 ei.mi = MaterialTable[threadID]->get_material_info(pos);
318 ei.value += ei.mi->material_value();
320 // If we have a specialized evaluation function for the current material
321 // configuration, call it and return
322 if (ei.mi->specialized_eval_exists())
323 return ei.mi->evaluate(pos);
325 // After get_material_info() call that modifies them
326 ScaleFactor factor[2];
327 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
328 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
330 // Probe the pawn hash table
331 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
332 ei.value += apply_weight(ei.pi->pawns_value(), WeightPawnStructure);
334 // Initialize king attack bitboards and king attack zones for both sides
335 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
336 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
337 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
338 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
340 // Initialize pawn attack bitboards for both sides
341 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
342 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
343 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
344 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
346 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
349 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
352 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
353 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
355 // Kings. Kings are evaluated after all other pieces for both sides,
356 // because we need complete attack information for all pieces when computing
357 // the king safety evaluation.
358 evaluate_king<WHITE, HasPopCnt>(pos, ei);
359 evaluate_king<BLACK, HasPopCnt>(pos, ei);
361 // Evaluate tactical threats, we need full attack info
362 evaluate_threats<WHITE>(pos, ei);
363 evaluate_threats<BLACK>(pos, ei);
365 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
366 // because we need to know which side promotes first in positions where
367 // both sides have an unstoppable passed pawn. To be called after all attacks
368 // are computed, included king.
369 if (ei.pi->passed_pawns())
370 evaluate_passed_pawns(pos, ei);
372 Phase phase = ei.mi->game_phase();
374 // Middle-game specific evaluation terms
375 if (phase > PHASE_ENDGAME)
377 // Pawn storms in positions with opposite castling.
378 if ( square_file(pos.king_square(WHITE)) >= FILE_E
379 && square_file(pos.king_square(BLACK)) <= FILE_D)
381 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
383 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
384 && square_file(pos.king_square(BLACK)) >= FILE_E)
386 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
388 // Evaluate space for both sides
389 if (ei.mi->space_weight() > 0)
391 evaluate_space<WHITE, HasPopCnt>(pos, ei);
392 evaluate_space<BLACK, HasPopCnt>(pos, ei);
397 ei.value += apply_weight(ei.mobility, WeightMobility);
399 // If we don't already have an unusual scale factor, check for opposite
400 // colored bishop endgames, and use a lower scale for those
401 if ( phase < PHASE_MIDGAME
402 && pos.opposite_colored_bishops()
403 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
404 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
408 // Only the two bishops ?
409 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
410 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
412 // Check for KBP vs KB with only a single pawn that is almost
413 // certainly a draw or at least two pawns.
414 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
415 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
418 // Endgame with opposite-colored bishops, but also other pieces. Still
419 // a bit drawish, but not as drawish as with only the two bishops.
420 sf = ScaleFactor(50);
422 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
424 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
428 // Interpolate between the middle game and the endgame score
429 Color stm = pos.side_to_move();
431 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
433 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
438 /// quick_evaluate() does a very approximate evaluation of the current position.
439 /// It currently considers only material and piece square table scores. Perhaps
440 /// we should add scores from the pawn and material hash tables?
442 Value quick_evaluate(const Position &pos) {
446 static const ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
448 Value v = scale_by_game_phase(pos.value(), MaterialInfoTable::game_phase(pos), sf);
449 return (pos.side_to_move() == WHITE ? v : -v);
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_outposts() evaluates bishop and knight outposts squares
519 template<PieceType Piece, Color Us>
520 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
522 const Color Them = (Us == WHITE ? BLACK : WHITE);
524 // Initial bonus based on square
525 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
526 : KnightOutpostBonus[relative_square(Us, s)]);
528 // Increase bonus if supported by pawn, especially if the opponent has
529 // no minor piece which can exchange the outpost piece
530 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
532 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
533 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
534 bonus += bonus + bonus / 2;
538 ei.value += Sign[Us] * make_score(bonus, bonus);
542 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
544 template<PieceType Piece, Color Us, bool HasPopCnt>
545 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
552 const Color Them = (Us == WHITE ? BLACK : WHITE);
553 const Square* ptr = pos.piece_list_begin(Us, Piece);
555 while ((s = *ptr++) != SQ_NONE)
557 // Find attacked squares, including x-ray attacks for bishops and rooks
558 if (Piece == KNIGHT || Piece == QUEEN)
559 b = pos.attacks_from<Piece>(s);
560 else if (Piece == BISHOP)
561 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
562 else if (Piece == ROOK)
563 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
567 // Update attack info
568 ei.attackedBy[Us][Piece] |= b;
571 if (b & ei.kingZone[Us])
573 ei.kingAttackersCount[Us]++;
574 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
575 Bitboard bb = (b & ei.attackedBy[Them][KING]);
577 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
581 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
582 : count_1s<HasPopCnt>(b & no_mob_area));
584 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
586 // Decrease score if we are attacked by an enemy pawn. Remaining part
587 // of threat evaluation must be done later when we have full attack info.
588 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
589 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
591 // Bishop and knight outposts squares
592 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
593 evaluate_outposts<Piece, Us>(pos, ei, s);
595 // Special patterns: trapped bishops on a7/h7/a2/h2
596 // and trapped bishops on a1/h1/a8/h8 in Chess960.
599 if (bit_is_set(MaskA7H7[Us], s))
600 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
602 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
603 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
606 // Queen or rook on 7th rank
607 if ( (Piece == ROOK || Piece == QUEEN)
608 && relative_rank(Us, s) == RANK_7
609 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
611 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
614 // Special extra evaluation for rooks
617 // Open and half-open files
619 if (ei.pi->file_is_half_open(Us, f))
621 if (ei.pi->file_is_half_open(Them, f))
622 ei.value += Sign[Us] * RookOpenFileBonus;
624 ei.value += Sign[Us] * RookHalfOpenFileBonus;
627 // Penalize rooks which are trapped inside a king. Penalize more if
628 // king has lost right to castle.
629 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
632 ksq = pos.king_square(Us);
634 if ( square_file(ksq) >= FILE_E
635 && square_file(s) > square_file(ksq)
636 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
638 // Is there a half-open file between the king and the edge of the board?
639 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
640 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
641 : (TrappedRookPenalty - mob * 16), 0);
643 else if ( square_file(ksq) <= FILE_D
644 && square_file(s) < square_file(ksq)
645 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
647 // Is there a half-open file between the king and the edge of the board?
648 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
649 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
650 : (TrappedRookPenalty - mob * 16), 0);
657 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
658 // and the type of attacked one.
661 void evaluate_threats(const Position& pos, EvalInfo& ei) {
663 const Color Them = (Us == WHITE ? BLACK : WHITE);
666 Score bonus = make_score(0, 0);
668 // Enemy pieces not defended by a pawn and under our attack
669 Bitboard weakEnemies = pos.pieces_of_color(Them)
670 & ~ei.attackedBy[Them][PAWN]
671 & ei.attackedBy[Us][0];
675 // Add bonus according to type of attacked enemy pieces and to the
676 // type of attacking piece, from knights to queens. Kings are not
677 // considered because are already special handled in king evaluation.
678 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
680 b = ei.attackedBy[Us][pt1] & weakEnemies;
682 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
683 if (b & pos.pieces(pt2))
684 bonus += ThreatBonus[pt1][pt2];
686 ei.value += Sign[Us] * bonus;
690 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
691 // pieces of a given color.
693 template<Color Us, bool HasPopCnt>
694 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
696 const Color Them = (Us == WHITE ? BLACK : WHITE);
698 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
699 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
701 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
702 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
703 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
704 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
706 // Sum up all attacked squares
707 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
708 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
709 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
713 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
715 template<Color Us, bool HasPopCnt>
716 void evaluate_king(const Position& pos, EvalInfo& ei) {
718 const Color Them = (Us == WHITE ? BLACK : WHITE);
720 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
723 int attackUnits, count, shelter = 0;
724 const Square s = pos.king_square(Us);
727 if (relative_rank(Us, s) <= RANK_4)
729 shelter = ei.pi->get_king_shelter(pos, Us, s);
730 ei.value += Sign[Us] * make_score(shelter, 0);
733 // King safety. This is quite complicated, and is almost certainly far
734 // from optimally tuned.
735 if ( pos.piece_count(Them, QUEEN) >= 1
736 && ei.kingAttackersCount[Them] >= 2
737 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
738 && ei.kingAdjacentZoneAttacksCount[Them])
740 // Is it the attackers turn to move?
741 sente = (Them == pos.side_to_move());
743 // Find the attacked squares around the king which has no defenders
744 // apart from the king itself
745 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
746 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
747 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
748 | ei.attacked_by(Us, QUEEN));
750 // Initialize the 'attackUnits' variable, which is used later on as an
751 // index to the SafetyTable[] array. The initial value is based on the
752 // number and types of the attacking pieces, the number of attacked and
753 // undefended squares around the king, the square of the king, and the
754 // quality of the pawn shelter.
755 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
756 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
757 + InitKingDanger[relative_square(Us, s)]
760 // Analyse safe queen contact checks
761 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
764 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
765 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
767 b &= attackedByOthers;
769 // Squares attacked by the queen and supported by another enemy piece and
770 // not defended by other pieces but our king.
773 // The bitboard b now contains the squares available for safe queen
775 count = count_1s_max_15<HasPopCnt>(b);
776 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
778 // Is there a mate threat?
779 if (QueenContactMates && !pos.is_check())
781 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
782 occ = pos.occupied_squares();
785 to = pop_1st_bit(&b);
787 // Do we have escape squares from queen contact check attack ?
788 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
790 // We have a mate, unless the queen is pinned or there
791 // is an X-ray attack through the queen.
792 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
794 from = pos.piece_list(Them, QUEEN, i);
795 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
796 && !bit_is_set(pos.pinned_pieces(Them), from)
797 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
798 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
800 // Set the mate threat move
801 ei.mateThreat[Them] = make_move(from, to);
809 // Analyse safe distance checks
810 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
812 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
814 b = pos.attacks_from<ROOK>(s) & safe;
817 b2 = b & ei.attacked_by(Them, QUEEN);
819 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
822 b2 = b & ei.attacked_by(Them, ROOK);
824 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
826 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
828 b = pos.attacks_from<BISHOP>(s) & safe;
831 b2 = b & ei.attacked_by(Them, QUEEN);
833 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
836 b2 = b & ei.attacked_by(Them, BISHOP);
838 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
840 if (KnightCheckBonus > 0)
842 b = pos.attacks_from<KNIGHT>(s) & safe;
845 b2 = b & ei.attacked_by(Them, KNIGHT);
847 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
850 // Analyse discovered checks (only for non-pawns right now, consider
851 // adding pawns later).
852 if (DiscoveredCheckBonus)
854 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
856 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
859 // Has a mate threat been found? We don't do anything here if the
860 // side with the mating move is the side to move, because in that
861 // case the mating side will get a huge bonus at the end of the main
862 // evaluation function instead.
863 if (ei.mateThreat[Them] != MOVE_NONE)
864 attackUnits += MateThreatBonus;
866 // Ensure that attackUnits is between 0 and 99, in order to avoid array
867 // out of bounds errors.
868 attackUnits = Min(99, Max(0, attackUnits));
870 // Finally, extract the king safety score from the SafetyTable[] array.
871 // Add the score to the evaluation, and also to ei.futilityMargin. The
872 // reason for adding the king safety score to the futility margin is
873 // that the king safety scores can sometimes be very big, and that
874 // capturing a single attacking piece can therefore result in a score
875 // change far bigger than the value of the captured piece.
876 Score v = apply_weight(make_score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
878 ei.value -= Sign[Us] * v;
880 if (Us == pos.side_to_move())
881 ei.futilityMargin += mg_value(v);
886 // evaluate_passed_pawns() evaluates the passed pawns of the given color
889 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
891 const Color Them = (Us == WHITE ? BLACK : WHITE);
894 Square ourKingSq = pos.king_square(Us);
895 Square theirKingSq = pos.king_square(Them);
896 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
900 Square s = pop_1st_bit(&b);
902 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
903 assert(pos.pawn_is_passed(Us, s));
905 int r = int(relative_rank(Us, s) - RANK_2);
906 int tr = Max(0, r * (r - 1));
908 // Base bonus based on rank
909 Value mbonus = Value(20 * tr);
910 Value ebonus = Value(10 + r * r * 10);
912 // Adjust bonus based on king proximity
915 Square blockSq = s + pawn_push(Us);
917 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
918 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
919 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
921 // If the pawn is free to advance, increase bonus
922 if (pos.square_is_empty(blockSq))
924 // There are no enemy pawns in the pawn's path
925 b2 = squares_in_front_of(Us, s);
927 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
929 // Squares attacked by us
930 b4 = b2 & ei.attacked_by(Us);
932 // Squares attacked or occupied by enemy pieces
933 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
935 // If there is an enemy rook or queen attacking the pawn from behind,
936 // add all X-ray attacks by the rook or queen.
937 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
938 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
941 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
942 if (b3 == EmptyBoardBB)
943 // No enemy attacks or pieces, huge bonus!
944 // Even bigger if we protect the pawn's path
945 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
947 // OK, there are enemy attacks or pieces (but not pawns). Are those
948 // squares which are attacked by the enemy also attacked by us ?
949 // If yes, big bonus (but smaller than when there are no enemy attacks),
950 // if no, somewhat smaller bonus.
951 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
953 // At last, add a small bonus when there are no *friendly* pieces
954 // in the pawn's path.
955 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
960 // If the pawn is supported by a friendly pawn, increase bonus
961 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
963 ebonus += Value(r * 20);
964 else if (pos.attacks_from<PAWN>(s, Them) & b2)
965 ebonus += Value(r * 12);
967 // If the other side has only a king, check whether the pawn is
969 if (pos.non_pawn_material(Them) == Value(0))
974 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
975 d = square_distance(s, qsq)
976 - square_distance(theirKingSq, qsq)
977 + (Us != pos.side_to_move());
981 int mtg = RANK_8 - relative_rank(Us, s);
982 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
985 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
993 // Rook pawns are a special case: They are sometimes worse, and
994 // sometimes better than other passed pawns. It is difficult to find
995 // good rules for determining whether they are good or bad. For now,
996 // we try the following: Increase the value for rook pawns if the
997 // other side has no pieces apart from a knight, and decrease the
998 // value if the other side has a rook or queen.
999 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1001 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1002 && pos.piece_count(Them, KNIGHT) <= 1)
1003 ebonus += ebonus / 4;
1004 else if (pos.pieces(ROOK, QUEEN, Them))
1005 ebonus -= ebonus / 4;
1008 // Add the scores for this pawn to the middle game and endgame eval.
1009 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
1015 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1017 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1019 int movesToGo[2] = {0, 0};
1020 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1022 // Evaluate pawns for each color
1023 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1024 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1026 // Neither side has an unstoppable passed pawn?
1027 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1030 // Does only one side have an unstoppable passed pawn?
1031 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1033 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1034 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1037 { // Both sides have unstoppable pawns! Try to find out who queens
1038 // first. We begin by transforming 'movesToGo' to the number of
1039 // plies until the pawn queens for both sides.
1040 movesToGo[WHITE] *= 2;
1041 movesToGo[BLACK] *= 2;
1042 movesToGo[pos.side_to_move()]--;
1044 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1045 Color loserSide = opposite_color(winnerSide);
1047 // If one side queens at least three plies before the other, that side wins
1048 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1049 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1051 // If one side queens one ply before the other and checks the king or attacks
1052 // the undefended opponent's queening square, that side wins. To avoid cases
1053 // where the opponent's king could move somewhere before first pawn queens we
1054 // consider only free paths to queen for both pawns.
1055 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1056 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1058 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1060 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1061 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1063 Bitboard b = pos.occupied_squares();
1064 clear_bit(&b, pawnToGo[winnerSide]);
1065 clear_bit(&b, pawnToGo[loserSide]);
1066 b = queen_attacks_bb(winnerQSq, b);
1068 if ( (b & pos.pieces(KING, loserSide))
1069 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1070 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1076 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1077 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1080 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1082 assert(square_is_ok(s));
1083 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1085 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1086 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1088 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1089 && pos.see(s, b6) < 0
1090 && pos.see(s, b8) < 0)
1092 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1097 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1098 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1099 // black), and assigns a penalty if it is. This pattern can obviously
1100 // only occur in Chess960 games.
1102 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1104 Piece pawn = piece_of_color_and_type(us, PAWN);
1108 assert(square_is_ok(s));
1109 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1111 if (square_file(s) == FILE_A)
1113 b2 = relative_square(us, SQ_B2);
1114 b3 = relative_square(us, SQ_B3);
1115 c3 = relative_square(us, SQ_C3);
1119 b2 = relative_square(us, SQ_G2);
1120 b3 = relative_square(us, SQ_G3);
1121 c3 = relative_square(us, SQ_F3);
1124 if (pos.piece_on(b2) == pawn)
1128 if (!pos.square_is_empty(b3))
1129 penalty = 2 * TrappedBishopA1H1Penalty;
1130 else if (pos.piece_on(c3) == pawn)
1131 penalty = TrappedBishopA1H1Penalty;
1133 penalty = TrappedBishopA1H1Penalty / 2;
1135 ei.value -= Sign[us] * penalty;
1140 // evaluate_space() computes the space evaluation for a given side. The
1141 // space evaluation is a simple bonus based on the number of safe squares
1142 // available for minor pieces on the central four files on ranks 2--4. Safe
1143 // squares one, two or three squares behind a friendly pawn are counted
1144 // twice. Finally, the space bonus is scaled by a weight taken from the
1145 // material hash table.
1146 template<Color Us, bool HasPopCnt>
1147 void evaluate_space(const Position& pos, EvalInfo& ei) {
1149 const Color Them = (Us == WHITE ? BLACK : WHITE);
1151 // Find the safe squares for our pieces inside the area defined by
1152 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1153 // pawn, or if it is undefended and attacked by an enemy piece.
1155 Bitboard safeSquares = SpaceMask[Us]
1156 & ~pos.pieces(PAWN, Us)
1157 & ~ei.attacked_by(Them, PAWN)
1158 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1160 // Find all squares which are at most three squares behind some friendly
1162 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1163 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1164 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1166 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1167 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1169 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1173 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1175 inline Score apply_weight(Score v, Score w) {
1176 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1180 // scale_by_game_phase() interpolates between a middle game and an endgame
1181 // score, based on game phase. It also scales the return value by a
1182 // ScaleFactor array.
1184 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1186 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1187 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1188 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1190 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1192 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1193 return Value(result & ~(GrainSize - 1));
1197 // weight_option() computes the value of an evaluation weight, by combining
1198 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1200 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1202 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1204 // Convert to integer to prevent overflow
1205 int mg = mg_value(uciWeight);
1206 int eg = eg_value(uciWeight);
1208 mg = (mg * 0x100) / 100;
1209 eg = (eg * 0x100) / 100;
1210 mg = (mg * mg_value(internalWeight)) / 0x100;
1211 eg = (eg * eg_value(internalWeight)) / 0x100;
1212 return make_score(mg, eg);
1215 // init_safety() initizes the king safety evaluation, based on UCI
1216 // parameters. It is called from read_weights().
1218 void init_safety() {
1220 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1221 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1222 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1223 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1224 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1225 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1226 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1228 int maxSlope = get_option_value_int("King Safety Max Slope");
1229 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1230 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1231 double b = get_option_value_int("King Safety X Intercept");
1232 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1233 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1235 for (int i = 0; i < 100; i++)
1238 SafetyTable[i] = Value(0);
1240 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1242 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1245 for (int i = 0; i < 100; i++)
1247 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1248 for (int j = i + 1; j < 100; j++)
1249 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1251 if (SafetyTable[i] > Value(peak))
1252 SafetyTable[i] = Value(peak);