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
68 // Visually better to define tables constants
70 #define S(mg, eg) make_score(mg, eg)
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 = make_score(47, 98);
144 const Score QueenOn7thBonus = make_score(27, 54);
146 // Rooks on open files (modified by Joona Kiiski)
147 const Score RookOpenFileBonus = make_score(43, 43);
148 const Score RookHalfOpenFileBonus = make_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 = make_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 = make_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 make_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
235 // InitKingDanger[] contains bonuses based on the position of the defending
237 const int InitKingDanger[64] = {
238 2, 0, 2, 5, 5, 2, 0, 2,
239 2, 2, 4, 8, 8, 4, 2, 2,
240 7, 10, 12, 12, 12, 12, 10, 7,
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,
245 15, 15, 15, 15, 15, 15, 15, 15
248 // SafetyTable[] contains the actual king safety scores. It is initialized
250 Value SafetyTable[100];
252 // Pawn and material hash tables, indexed by the current thread id
253 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
254 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
256 // Sizes of pawn and material hash tables
257 const int PawnTableSize = 16384;
258 const int MaterialTableSize = 1024;
260 // Function prototypes
261 template<bool HasPopCnt>
262 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
264 template<Color Us, bool HasPopCnt>
265 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
267 template<Color Us, bool HasPopCnt>
268 void evaluate_king(const Position& pos, EvalInfo& ei);
271 void evaluate_threats(const Position& pos, EvalInfo& ei);
273 template<Color Us, bool HasPopCnt>
274 void evaluate_space(const Position& pos, EvalInfo& ei);
276 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
277 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
278 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
279 inline Score apply_weight(Score v, Score weight);
280 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
281 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
290 /// evaluate() is the main evaluation function. It always computes two
291 /// values, an endgame score and a middle game score, and interpolates
292 /// between them based on the remaining material.
293 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
295 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
296 : do_evaluate<false>(pos, ei, threadID);
301 template<bool HasPopCnt>
302 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
305 assert(threadID >= 0 && threadID < THREAD_MAX);
306 assert(!pos.is_check());
308 memset(&ei, 0, sizeof(EvalInfo));
310 // Initialize by reading the incrementally updated scores included in the
311 // position object (material + piece square tables)
312 ei.value = pos.value();
314 // Probe the material hash table
315 ei.mi = MaterialTable[threadID]->get_material_info(pos);
316 ei.value += ei.mi->material_value();
318 // If we have a specialized evaluation function for the current material
319 // configuration, call it and return
320 if (ei.mi->specialized_eval_exists())
321 return ei.mi->evaluate(pos);
323 // After get_material_info() call that modifies them
324 ScaleFactor factor[2];
325 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
326 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
328 // Probe the pawn hash table
329 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
330 ei.value += apply_weight(ei.pi->value(), WeightPawnStructure);
332 // Initialize king attack bitboards and king attack zones for both sides
333 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
334 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
335 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
336 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
338 // Initialize pawn attack bitboards for both sides
339 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
340 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
341 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
342 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
344 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
347 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
350 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
351 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
353 // Kings. Kings are evaluated after all other pieces for both sides,
354 // because we need complete attack information for all pieces when computing
355 // the king safety evaluation.
356 evaluate_king<WHITE, HasPopCnt>(pos, ei);
357 evaluate_king<BLACK, HasPopCnt>(pos, ei);
359 // Evaluate tactical threats, we need full attack info
360 evaluate_threats<WHITE>(pos, ei);
361 evaluate_threats<BLACK>(pos, ei);
363 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
364 // because we need to know which side promotes first in positions where
365 // both sides have an unstoppable passed pawn. To be called after all attacks
366 // are computed, included king.
367 if (ei.pi->passed_pawns())
368 evaluate_passed_pawns(pos, ei);
370 Phase phase = pos.game_phase();
372 // Middle-game specific evaluation terms
373 if (phase > PHASE_ENDGAME)
375 // Pawn storms in positions with opposite castling.
376 if ( square_file(pos.king_square(WHITE)) >= FILE_E
377 && square_file(pos.king_square(BLACK)) <= FILE_D)
379 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
381 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
382 && square_file(pos.king_square(BLACK)) >= FILE_E)
384 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
386 // Evaluate space for both sides
387 if (ei.mi->space_weight() > 0)
389 evaluate_space<WHITE, HasPopCnt>(pos, ei);
390 evaluate_space<BLACK, HasPopCnt>(pos, ei);
395 ei.value += apply_weight(ei.mobility, WeightMobility);
397 // If we don't already have an unusual scale factor, check for opposite
398 // colored bishop endgames, and use a lower scale for those
399 if ( phase < PHASE_MIDGAME
400 && pos.opposite_colored_bishops()
401 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
402 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
406 // Only the two bishops ?
407 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
408 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
410 // Check for KBP vs KB with only a single pawn that is almost
411 // certainly a draw or at least two pawns.
412 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
413 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
416 // Endgame with opposite-colored bishops, but also other pieces. Still
417 // a bit drawish, but not as drawish as with only the two bishops.
418 sf = ScaleFactor(50);
420 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
422 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
426 // Interpolate between the middle game and the endgame score
427 Color stm = pos.side_to_move();
429 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
431 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
436 /// quick_evaluate() does a very approximate evaluation of the current position.
437 /// It currently considers only material and piece square table scores. Perhaps
438 /// we should add scores from the pawn and material hash tables?
440 Value quick_evaluate(const Position &pos) {
445 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
447 Phase ph = pos.game_phase();
448 Color stm = pos.side_to_move();
450 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
454 /// init_eval() initializes various tables used by the evaluation function
456 void init_eval(int threads) {
458 assert(threads <= THREAD_MAX);
460 for (int i = 0; i < THREAD_MAX; i++)
465 delete MaterialTable[i];
467 MaterialTable[i] = NULL;
471 PawnTable[i] = new PawnInfoTable(PawnTableSize);
472 if (!MaterialTable[i])
473 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
478 /// quit_eval() releases heap-allocated memory at program termination
482 for (int i = 0; i < THREAD_MAX; i++)
485 delete MaterialTable[i];
487 MaterialTable[i] = NULL;
492 /// read_weights() reads evaluation weights from the corresponding UCI parameters
494 void read_weights(Color us) {
496 Color them = opposite_color(us);
498 WeightMobility = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightMobilityInternal);
499 WeightPawnStructure = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightPawnStructureInternal);
500 WeightPassedPawns = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightPassedPawnsInternal);
501 WeightSpace = weight_option("Space", "Space", WeightSpaceInternal);
502 WeightKingSafety[us] = weight_option("Cowardice", "Cowardice", WeightKingSafetyInternal);
503 WeightKingSafety[them] = weight_option("Aggressiveness", "Aggressiveness", WeightKingOppSafetyInternal);
505 // If running in analysis mode, make sure we use symmetrical king safety. We do this
506 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
507 if (get_option_value_bool("UCI_AnalyseMode"))
509 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
510 WeightKingSafety[them] = WeightKingSafety[us];
518 // evaluate_mobility() computes mobility and attacks for every piece
520 template<PieceType Piece, Color Us, bool HasPopCnt>
521 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
523 const Color Them = (Us == WHITE ? BLACK : WHITE);
525 // Update attack info
526 ei.attackedBy[Us][Piece] |= b;
529 if (b & ei.kingZone[Us])
531 ei.kingAttackersCount[Us]++;
532 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
533 Bitboard bb = (b & ei.attackedBy[Them][KING]);
535 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
539 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
540 : count_1s<HasPopCnt>(b & mob_area));
542 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
547 // evaluate_outposts() evaluates bishop and knight outposts squares
549 template<PieceType Piece, Color Us>
550 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
552 const Color Them = (Us == WHITE ? BLACK : WHITE);
554 // Initial bonus based on square
555 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
556 : KnightOutpostBonus[relative_square(Us, s)]);
558 // Increase bonus if supported by pawn, especially if the opponent has
559 // no minor piece which can exchange the outpost piece
560 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
562 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
563 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
564 bonus += bonus + bonus / 2;
568 ei.value += Sign[Us] * make_score(bonus, bonus);
572 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
574 template<PieceType Piece, Color Us, bool HasPopCnt>
575 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
582 const Color Them = (Us == WHITE ? BLACK : WHITE);
583 const Square* ptr = pos.piece_list_begin(Us, Piece);
585 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
586 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
588 while ((s = *ptr++) != SQ_NONE)
590 if (Piece == KNIGHT || Piece == QUEEN)
591 b = pos.attacks_from<Piece>(s);
592 else if (Piece == BISHOP)
593 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
594 else if (Piece == ROOK)
595 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
599 // Attacks and mobility
600 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
602 // Decrease score if we are attacked by an enemy pawn. Remaining part
603 // of threat evaluation must be done later when we have full attack info.
604 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
605 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
607 // Bishop and knight outposts squares
608 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
609 evaluate_outposts<Piece, Us>(pos, ei, s);
611 // Special patterns: trapped bishops on a7/h7/a2/h2
612 // and trapped bishops on a1/h1/a8/h8 in Chess960.
615 if (bit_is_set(MaskA7H7[Us], s))
616 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
618 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
619 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
622 if (Piece == ROOK || Piece == QUEEN)
624 // Queen or rook on 7th rank
625 if ( relative_rank(Us, s) == RANK_7
626 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
628 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
632 // Special extra evaluation for rooks
635 // Open and half-open files
637 if (ei.pi->file_is_half_open(Us, f))
639 if (ei.pi->file_is_half_open(Them, f))
640 ei.value += Sign[Us] * RookOpenFileBonus;
642 ei.value += Sign[Us] * RookHalfOpenFileBonus;
645 // Penalize rooks which are trapped inside a king. Penalize more if
646 // king has lost right to castle.
647 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
650 ksq = pos.king_square(Us);
652 if ( square_file(ksq) >= FILE_E
653 && square_file(s) > square_file(ksq)
654 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
656 // Is there a half-open file between the king and the edge of the board?
657 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
658 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
659 : (TrappedRookPenalty - mob * 16), 0);
661 else if ( square_file(ksq) <= FILE_D
662 && square_file(s) < square_file(ksq)
663 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
665 // Is there a half-open file between the king and the edge of the board?
666 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
667 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
668 : (TrappedRookPenalty - mob * 16), 0);
675 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
676 // and the type of attacked one.
679 void evaluate_threats(const Position& pos, EvalInfo& ei) {
681 const Color Them = (Us == WHITE ? BLACK : WHITE);
684 Score bonus = make_score(0, 0);
686 // Enemy pieces not defended by a pawn and under our attack
687 Bitboard weakEnemies = pos.pieces_of_color(Them)
688 & ~ei.attackedBy[Them][PAWN]
689 & ei.attackedBy[Us][0];
693 // Add bonus according to type of attacked enemy pieces and to the
694 // type of attacking piece, from knights to queens. Kings are not
695 // considered because are already special handled in king evaluation.
696 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
698 b = ei.attackedBy[Us][pt1] & weakEnemies;
700 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
701 if (b & pos.pieces(pt2))
702 bonus += ThreatBonus[pt1][pt2];
704 ei.value += Sign[Us] * bonus;
708 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
709 // pieces of a given color.
711 template<Color Us, bool HasPopCnt>
712 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
714 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
715 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
716 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
717 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
719 // Sum up all attacked squares
720 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
721 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
722 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
726 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
728 template<Color Us, bool HasPopCnt>
729 void evaluate_king(const Position& pos, EvalInfo& ei) {
731 const Color Them = (Us == WHITE ? BLACK : WHITE);
732 const Square s = pos.king_square(Us);
736 if (relative_rank(Us, s) <= RANK_4)
738 shelter = ei.pi->get_king_shelter(pos, Us, s);
739 ei.value += Sign[Us] * make_score(shelter, 0);
742 // King safety. This is quite complicated, and is almost certainly far
743 // from optimally tuned.
744 if ( pos.piece_count(Them, QUEEN) >= 1
745 && ei.kingAttackersCount[Them] >= 2
746 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
747 && ei.kingAdjacentZoneAttacksCount[Them])
749 // Is it the attackers turn to move?
750 bool sente = (Them == pos.side_to_move());
752 // Find the attacked squares around the king which has no defenders
753 // apart from the king itself
754 Bitboard undefended =
755 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
756 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
757 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
758 & ei.attacked_by(Us, KING);
760 Bitboard occ = pos.occupied_squares(), b, b2;
762 // Initialize the 'attackUnits' variable, which is used later on as an
763 // index to the SafetyTable[] array. The initial value is based on the
764 // number and types of the attacking pieces, the number of attacked and
765 // undefended squares around the king, the square of the king, and the
766 // quality of the pawn shelter.
768 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
769 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
770 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
772 // Analyse safe queen contact checks
773 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
776 Bitboard attackedByOthers =
777 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
778 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
780 b &= attackedByOthers;
783 // The bitboard b now contains the squares available for safe queen
785 int count = count_1s_max_15<HasPopCnt>(b);
786 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
788 // Is there a mate threat?
789 if (QueenContactMates && !pos.is_check())
791 Bitboard escapeSquares =
792 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
796 Square from, to = pop_1st_bit(&b);
797 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
799 // We have a mate, unless the queen is pinned or there
800 // is an X-ray attack through the queen.
801 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
803 from = pos.piece_list(Them, QUEEN, i);
804 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
805 && !bit_is_set(pos.pinned_pieces(Them), from)
806 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
807 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
809 ei.mateThreat[Them] = make_move(from, to);
817 // Analyse safe distance checks
818 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
820 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
823 b2 = b & ei.attacked_by(Them, QUEEN);
825 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
828 b2 = b & ei.attacked_by(Them, ROOK);
830 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
832 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
834 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
837 b2 = b & ei.attacked_by(Them, QUEEN);
839 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
842 b2 = b & ei.attacked_by(Them, BISHOP);
844 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
846 if (KnightCheckBonus > 0)
848 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
851 b2 = b & ei.attacked_by(Them, KNIGHT);
853 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
856 // Analyse discovered checks (only for non-pawns right now, consider
857 // adding pawns later).
858 if (DiscoveredCheckBonus)
860 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
862 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
865 // Has a mate threat been found? We don't do anything here if the
866 // side with the mating move is the side to move, because in that
867 // case the mating side will get a huge bonus at the end of the main
868 // evaluation function instead.
869 if (ei.mateThreat[Them] != MOVE_NONE)
870 attackUnits += MateThreatBonus;
872 // Ensure that attackUnits is between 0 and 99, in order to avoid array
873 // out of bounds errors:
877 if (attackUnits >= 100)
880 // Finally, extract the king safety score from the SafetyTable[] array.
881 // Add the score to the evaluation, and also to ei.futilityMargin. The
882 // reason for adding the king safety score to the futility margin is
883 // that the king safety scores can sometimes be very big, and that
884 // capturing a single attacking piece can therefore result in a score
885 // change far bigger than the value of the captured piece.
886 Score v = apply_weight(make_score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
888 ei.value -= Sign[Us] * v;
890 if (Us == pos.side_to_move())
891 ei.futilityMargin += mg_value(v);
896 // evaluate_passed_pawns() evaluates the passed pawns of the given color
899 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
901 const Color Them = (Us == WHITE ? BLACK : WHITE);
904 Square ourKingSq = pos.king_square(Us);
905 Square theirKingSq = pos.king_square(Them);
906 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
910 Square s = pop_1st_bit(&b);
912 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
913 assert(pos.pawn_is_passed(Us, s));
915 int r = int(relative_rank(Us, s) - RANK_2);
916 int tr = Max(0, r * (r - 1));
918 // Base bonus based on rank
919 Value mbonus = Value(20 * tr);
920 Value ebonus = Value(10 + r * r * 10);
922 // Adjust bonus based on king proximity
925 Square blockSq = s + pawn_push(Us);
927 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
928 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
929 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
931 // If the pawn is free to advance, increase bonus
932 if (pos.square_is_empty(blockSq))
934 // There are no enemy pawns in the pawn's path
935 b2 = squares_in_front_of(Us, s);
937 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
939 // Squares attacked by us
940 b4 = b2 & ei.attacked_by(Us);
942 // Squares attacked or occupied by enemy pieces
943 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
945 // If there is an enemy rook or queen attacking the pawn from behind,
946 // add all X-ray attacks by the rook or queen.
947 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
948 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
951 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
952 if (b3 == EmptyBoardBB)
953 // No enemy attacks or pieces, huge bonus!
954 // Even bigger if we protect the pawn's path
955 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
957 // OK, there are enemy attacks or pieces (but not pawns). Are those
958 // squares which are attacked by the enemy also attacked by us ?
959 // If yes, big bonus (but smaller than when there are no enemy attacks),
960 // if no, somewhat smaller bonus.
961 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
963 // At last, add a small bonus when there are no *friendly* pieces
964 // in the pawn's path.
965 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
970 // If the pawn is supported by a friendly pawn, increase bonus
971 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
973 ebonus += Value(r * 20);
974 else if (pos.attacks_from<PAWN>(s, Them) & b2)
975 ebonus += Value(r * 12);
977 // If the other side has only a king, check whether the pawn is
979 if (pos.non_pawn_material(Them) == Value(0))
984 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
985 d = square_distance(s, qsq)
986 - square_distance(theirKingSq, qsq)
987 + (Us != pos.side_to_move());
991 int mtg = RANK_8 - relative_rank(Us, s);
992 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
995 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1003 // Rook pawns are a special case: They are sometimes worse, and
1004 // sometimes better than other passed pawns. It is difficult to find
1005 // good rules for determining whether they are good or bad. For now,
1006 // we try the following: Increase the value for rook pawns if the
1007 // other side has no pieces apart from a knight, and decrease the
1008 // value if the other side has a rook or queen.
1009 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1011 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1012 && pos.piece_count(Them, KNIGHT) <= 1)
1013 ebonus += ebonus / 4;
1014 else if (pos.pieces(ROOK, QUEEN, Them))
1015 ebonus -= ebonus / 4;
1018 // Add the scores for this pawn to the middle game and endgame eval.
1019 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
1025 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1027 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1029 int movesToGo[2] = {0, 0};
1030 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1032 // Evaluate pawns for each color
1033 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1034 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1036 // Neither side has an unstoppable passed pawn?
1037 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1040 // Does only one side have an unstoppable passed pawn?
1041 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1043 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1044 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1047 { // Both sides have unstoppable pawns! Try to find out who queens
1048 // first. We begin by transforming 'movesToGo' to the number of
1049 // plies until the pawn queens for both sides.
1050 movesToGo[WHITE] *= 2;
1051 movesToGo[BLACK] *= 2;
1052 movesToGo[pos.side_to_move()]--;
1054 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1055 Color loserSide = opposite_color(winnerSide);
1057 // If one side queens at least three plies before the other, that side wins
1058 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1059 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1061 // If one side queens one ply before the other and checks the king or attacks
1062 // the undefended opponent's queening square, that side wins. To avoid cases
1063 // where the opponent's king could move somewhere before first pawn queens we
1064 // consider only free paths to queen for both pawns.
1065 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1066 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1068 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1070 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1071 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1073 Bitboard b = pos.occupied_squares();
1074 clear_bit(&b, pawnToGo[winnerSide]);
1075 clear_bit(&b, pawnToGo[loserSide]);
1076 b = queen_attacks_bb(winnerQSq, b);
1078 if ( (b & pos.pieces(KING, loserSide))
1079 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1080 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1086 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1087 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1090 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1092 assert(square_is_ok(s));
1093 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1095 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1096 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1098 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1099 && pos.see(s, b6) < 0
1100 && pos.see(s, b8) < 0)
1102 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1107 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1108 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1109 // black), and assigns a penalty if it is. This pattern can obviously
1110 // only occur in Chess960 games.
1112 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1114 Piece pawn = piece_of_color_and_type(us, PAWN);
1118 assert(square_is_ok(s));
1119 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1121 if (square_file(s) == FILE_A)
1123 b2 = relative_square(us, SQ_B2);
1124 b3 = relative_square(us, SQ_B3);
1125 c3 = relative_square(us, SQ_C3);
1129 b2 = relative_square(us, SQ_G2);
1130 b3 = relative_square(us, SQ_G3);
1131 c3 = relative_square(us, SQ_F3);
1134 if (pos.piece_on(b2) == pawn)
1138 if (!pos.square_is_empty(b3))
1139 penalty = 2 * TrappedBishopA1H1Penalty;
1140 else if (pos.piece_on(c3) == pawn)
1141 penalty = TrappedBishopA1H1Penalty;
1143 penalty = TrappedBishopA1H1Penalty / 2;
1145 ei.value -= Sign[us] * penalty;
1150 // evaluate_space() computes the space evaluation for a given side. The
1151 // space evaluation is a simple bonus based on the number of safe squares
1152 // available for minor pieces on the central four files on ranks 2--4. Safe
1153 // squares one, two or three squares behind a friendly pawn are counted
1154 // twice. Finally, the space bonus is scaled by a weight taken from the
1155 // material hash table.
1156 template<Color Us, bool HasPopCnt>
1157 void evaluate_space(const Position& pos, EvalInfo& ei) {
1159 const Color Them = (Us == WHITE ? BLACK : WHITE);
1161 // Find the safe squares for our pieces inside the area defined by
1162 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1163 // pawn, or if it is undefended and attacked by an enemy piece.
1165 Bitboard safeSquares = SpaceMask[Us]
1166 & ~pos.pieces(PAWN, Us)
1167 & ~ei.attacked_by(Them, PAWN)
1168 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1170 // Find all squares which are at most three squares behind some friendly
1172 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1173 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1174 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1176 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1177 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1179 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1183 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1185 inline Score apply_weight(Score v, Score w) {
1186 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1190 // scale_by_game_phase() interpolates between a middle game and an endgame
1191 // score, based on game phase. It also scales the return value by a
1192 // ScaleFactor array.
1194 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1196 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1197 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1198 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1200 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1202 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1203 return Value(result & ~(GrainSize - 1));
1207 // weight_option() computes the value of an evaluation weight, by combining
1208 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1210 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1212 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1214 // Convert to integer to prevent overflow
1215 int mg = mg_value(uciWeight);
1216 int eg = eg_value(uciWeight);
1218 mg = (mg * 0x100) / 100;
1219 eg = (eg * 0x100) / 100;
1220 mg = (mg * mg_value(internalWeight)) / 0x100;
1221 eg = (eg * eg_value(internalWeight)) / 0x100;
1222 return make_score(mg, eg);
1225 // init_safety() initizes the king safety evaluation, based on UCI
1226 // parameters. It is called from read_weights().
1228 void init_safety() {
1230 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1231 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1232 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1233 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1234 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1235 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1236 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1238 int maxSlope = get_option_value_int("King Safety Max Slope");
1239 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1240 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1241 double b = get_option_value_int("King Safety X Intercept");
1242 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1243 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1245 for (int i = 0; i < 100; i++)
1248 SafetyTable[i] = Value(0);
1250 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1252 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1255 for (int i = 0; i < 100; i++)
1257 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1258 for (int j = i + 1; j < 100; j++)
1259 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1261 if (SafetyTable[i] > Value(peak))
1262 SafetyTable[i] = Value(peak);