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 // Note that they will be initialized at 0 being global variables.
256 MaterialInfoTable* MaterialTable[THREAD_MAX];
257 PawnInfoTable* PawnTable[THREAD_MAX];
259 // Sizes of pawn and material hash tables
260 const int PawnTableSize = 16384;
261 const int MaterialTableSize = 1024;
263 // Function prototypes
264 template<bool HasPopCnt>
265 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
267 template<Color Us, bool HasPopCnt>
268 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
270 template<Color Us, bool HasPopCnt>
271 void evaluate_king(const Position& pos, EvalInfo& ei);
274 void evaluate_threats(const Position& pos, EvalInfo& ei);
276 template<Color Us, bool HasPopCnt>
277 void evaluate_space(const Position& pos, EvalInfo& ei);
279 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
280 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
281 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
282 inline Score apply_weight(Score v, Score weight);
283 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
284 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
293 /// evaluate() is the main evaluation function. It always computes two
294 /// values, an endgame score and a middle game score, and interpolates
295 /// between them based on the remaining material.
296 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
298 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
299 : do_evaluate<false>(pos, ei, threadID);
304 template<bool HasPopCnt>
305 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
308 assert(threadID >= 0 && threadID < THREAD_MAX);
309 assert(!pos.is_check());
311 memset(&ei, 0, sizeof(EvalInfo));
313 // Initialize by reading the incrementally updated scores included in the
314 // position object (material + piece square tables)
315 ei.value = pos.value();
317 // Probe the material hash table
318 ei.mi = MaterialTable[threadID]->get_material_info(pos);
319 ei.value += ei.mi->material_value();
321 // If we have a specialized evaluation function for the current material
322 // configuration, call it and return
323 if (ei.mi->specialized_eval_exists())
324 return ei.mi->evaluate(pos);
326 // After get_material_info() call that modifies them
327 ScaleFactor factor[2];
328 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
329 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
331 // Probe the pawn hash table
332 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
333 ei.value += apply_weight(ei.pi->pawns_value(), WeightPawnStructure);
335 // Initialize king attack bitboards and king attack zones for both sides
336 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
337 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
338 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
339 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
341 // Initialize pawn attack bitboards for both sides
342 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
343 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
344 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
345 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
347 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
350 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
353 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
354 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
356 // Kings. Kings are evaluated after all other pieces for both sides,
357 // because we need complete attack information for all pieces when computing
358 // the king safety evaluation.
359 evaluate_king<WHITE, HasPopCnt>(pos, ei);
360 evaluate_king<BLACK, HasPopCnt>(pos, ei);
362 // Evaluate tactical threats, we need full attack info
363 evaluate_threats<WHITE>(pos, ei);
364 evaluate_threats<BLACK>(pos, ei);
366 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
367 // because we need to know which side promotes first in positions where
368 // both sides have an unstoppable passed pawn. To be called after all attacks
369 // are computed, included king.
370 if (ei.pi->passed_pawns())
371 evaluate_passed_pawns(pos, ei);
373 Phase phase = ei.mi->game_phase();
375 // Middle-game specific evaluation terms
376 if (phase > PHASE_ENDGAME)
378 // Pawn storms in positions with opposite castling.
379 if ( square_file(pos.king_square(WHITE)) >= FILE_E
380 && square_file(pos.king_square(BLACK)) <= FILE_D)
382 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
384 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
385 && square_file(pos.king_square(BLACK)) >= FILE_E)
387 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
389 // Evaluate space for both sides
390 if (ei.mi->space_weight() > 0)
392 evaluate_space<WHITE, HasPopCnt>(pos, ei);
393 evaluate_space<BLACK, HasPopCnt>(pos, ei);
398 ei.value += apply_weight(ei.mobility, WeightMobility);
400 // If we don't already have an unusual scale factor, check for opposite
401 // colored bishop endgames, and use a lower scale for those
402 if ( phase < PHASE_MIDGAME
403 && pos.opposite_colored_bishops()
404 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
405 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
409 // Only the two bishops ?
410 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
411 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
413 // Check for KBP vs KB with only a single pawn that is almost
414 // certainly a draw or at least two pawns.
415 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
416 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
419 // Endgame with opposite-colored bishops, but also other pieces. Still
420 // a bit drawish, but not as drawish as with only the two bishops.
421 sf = ScaleFactor(50);
423 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
425 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
429 // Interpolate between the middle game and the endgame score
430 Color stm = pos.side_to_move();
432 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
434 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
439 /// quick_evaluate() does a very approximate evaluation of the current position.
440 /// It currently considers only material and piece square table scores. Perhaps
441 /// we should add scores from the pawn and material hash tables?
443 Value quick_evaluate(const Position &pos) {
447 static const ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
449 Value v = scale_by_game_phase(pos.value(), MaterialInfoTable::game_phase(pos), sf);
450 return (pos.side_to_move() == WHITE ? v : -v);
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_outposts() evaluates bishop and knight outposts squares
520 template<PieceType Piece, Color Us>
521 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
523 const Color Them = (Us == WHITE ? BLACK : WHITE);
525 // Initial bonus based on square
526 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
527 : KnightOutpostBonus[relative_square(Us, s)]);
529 // Increase bonus if supported by pawn, especially if the opponent has
530 // no minor piece which can exchange the outpost piece
531 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
533 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
534 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
535 bonus += bonus + bonus / 2;
539 ei.value += Sign[Us] * make_score(bonus, bonus);
543 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
545 template<PieceType Piece, Color Us, bool HasPopCnt>
546 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
553 const Color Them = (Us == WHITE ? BLACK : WHITE);
554 const Square* ptr = pos.piece_list_begin(Us, Piece);
556 while ((s = *ptr++) != SQ_NONE)
558 // Find attacked squares, including x-ray attacks for bishops and rooks
559 if (Piece == KNIGHT || Piece == QUEEN)
560 b = pos.attacks_from<Piece>(s);
561 else if (Piece == BISHOP)
562 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
563 else if (Piece == ROOK)
564 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
568 // Update attack info
569 ei.attackedBy[Us][Piece] |= b;
572 if (b & ei.kingZone[Us])
574 ei.kingAttackersCount[Us]++;
575 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
576 Bitboard bb = (b & ei.attackedBy[Them][KING]);
578 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
582 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
583 : count_1s<HasPopCnt>(b & no_mob_area));
585 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
587 // Decrease score if we are attacked by an enemy pawn. Remaining part
588 // of threat evaluation must be done later when we have full attack info.
589 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
590 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
592 // Bishop and knight outposts squares
593 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
594 evaluate_outposts<Piece, Us>(pos, ei, s);
596 // Special patterns: trapped bishops on a7/h7/a2/h2
597 // and trapped bishops on a1/h1/a8/h8 in Chess960.
600 if (bit_is_set(MaskA7H7[Us], s))
601 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
603 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
604 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
607 // Queen or rook on 7th rank
608 if ( (Piece == ROOK || Piece == QUEEN)
609 && relative_rank(Us, s) == RANK_7
610 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
612 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
615 // Special extra evaluation for rooks
618 // Open and half-open files
620 if (ei.pi->file_is_half_open(Us, f))
622 if (ei.pi->file_is_half_open(Them, f))
623 ei.value += Sign[Us] * RookOpenFileBonus;
625 ei.value += Sign[Us] * RookHalfOpenFileBonus;
628 // Penalize rooks which are trapped inside a king. Penalize more if
629 // king has lost right to castle.
630 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
633 ksq = pos.king_square(Us);
635 if ( square_file(ksq) >= FILE_E
636 && square_file(s) > square_file(ksq)
637 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
639 // Is there a half-open file between the king and the edge of the board?
640 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
641 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
642 : (TrappedRookPenalty - mob * 16), 0);
644 else if ( square_file(ksq) <= FILE_D
645 && square_file(s) < square_file(ksq)
646 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
648 // Is there a half-open file between the king and the edge of the board?
649 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
650 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
651 : (TrappedRookPenalty - mob * 16), 0);
658 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
659 // and the type of attacked one.
662 void evaluate_threats(const Position& pos, EvalInfo& ei) {
664 const Color Them = (Us == WHITE ? BLACK : WHITE);
667 Score bonus = make_score(0, 0);
669 // Enemy pieces not defended by a pawn and under our attack
670 Bitboard weakEnemies = pos.pieces_of_color(Them)
671 & ~ei.attackedBy[Them][PAWN]
672 & ei.attackedBy[Us][0];
676 // Add bonus according to type of attacked enemy pieces and to the
677 // type of attacking piece, from knights to queens. Kings are not
678 // considered because are already special handled in king evaluation.
679 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
681 b = ei.attackedBy[Us][pt1] & weakEnemies;
683 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
684 if (b & pos.pieces(pt2))
685 bonus += ThreatBonus[pt1][pt2];
687 ei.value += Sign[Us] * bonus;
691 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
692 // pieces of a given color.
694 template<Color Us, bool HasPopCnt>
695 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
697 const Color Them = (Us == WHITE ? BLACK : WHITE);
699 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
700 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
702 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
703 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
704 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
705 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
707 // Sum up all attacked squares
708 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
709 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
710 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
714 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
716 template<Color Us, bool HasPopCnt>
717 void evaluate_king(const Position& pos, EvalInfo& ei) {
719 const Color Them = (Us == WHITE ? BLACK : WHITE);
721 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
724 int attackUnits, count, shelter = 0;
725 const Square s = pos.king_square(Us);
728 if (relative_rank(Us, s) <= RANK_4)
730 shelter = ei.pi->get_king_shelter(pos, Us, s);
731 ei.value += Sign[Us] * make_score(shelter, 0);
734 // King safety. This is quite complicated, and is almost certainly far
735 // from optimally tuned.
736 if ( pos.piece_count(Them, QUEEN) >= 1
737 && ei.kingAttackersCount[Them] >= 2
738 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
739 && ei.kingAdjacentZoneAttacksCount[Them])
741 // Is it the attackers turn to move?
742 sente = (Them == pos.side_to_move());
744 // Find the attacked squares around the king which has no defenders
745 // apart from the king itself
746 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
747 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
748 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
749 | ei.attacked_by(Us, QUEEN));
751 // Initialize the 'attackUnits' variable, which is used later on as an
752 // index to the SafetyTable[] array. The initial value is based on the
753 // number and types of the attacking pieces, the number of attacked and
754 // undefended squares around the king, the square of the king, and the
755 // quality of the pawn shelter.
756 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
757 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
758 + InitKingDanger[relative_square(Us, s)]
761 // Analyse safe queen contact checks
762 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
765 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
766 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
768 b &= attackedByOthers;
770 // Squares attacked by the queen and supported by another enemy piece and
771 // not defended by other pieces but our king.
774 // The bitboard b now contains the squares available for safe queen
776 count = count_1s_max_15<HasPopCnt>(b);
777 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
779 // Is there a mate threat?
780 if (QueenContactMates && !pos.is_check())
782 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
783 occ = pos.occupied_squares();
786 to = pop_1st_bit(&b);
788 // Do we have escape squares from queen contact check attack ?
789 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
791 // We have a mate, unless the queen is pinned or there
792 // is an X-ray attack through the queen.
793 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
795 from = pos.piece_list(Them, QUEEN, i);
796 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
797 && !bit_is_set(pos.pinned_pieces(Them), from)
798 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
799 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
801 // Set the mate threat move
802 ei.mateThreat[Them] = make_move(from, to);
810 // Analyse safe distance checks
811 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
813 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
815 b = pos.attacks_from<ROOK>(s) & safe;
818 b2 = b & ei.attacked_by(Them, QUEEN);
820 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
823 b2 = b & ei.attacked_by(Them, ROOK);
825 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
827 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
829 b = pos.attacks_from<BISHOP>(s) & safe;
832 b2 = b & ei.attacked_by(Them, QUEEN);
834 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
837 b2 = b & ei.attacked_by(Them, BISHOP);
839 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
841 if (KnightCheckBonus > 0)
843 b = pos.attacks_from<KNIGHT>(s) & safe;
846 b2 = b & ei.attacked_by(Them, KNIGHT);
848 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
851 // Analyse discovered checks (only for non-pawns right now, consider
852 // adding pawns later).
853 if (DiscoveredCheckBonus)
855 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
857 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
860 // Has a mate threat been found? We don't do anything here if the
861 // side with the mating move is the side to move, because in that
862 // case the mating side will get a huge bonus at the end of the main
863 // evaluation function instead.
864 if (ei.mateThreat[Them] != MOVE_NONE)
865 attackUnits += MateThreatBonus;
867 // Ensure that attackUnits is between 0 and 99, in order to avoid array
868 // out of bounds errors.
869 attackUnits = Min(99, Max(0, attackUnits));
871 // Finally, extract the king safety score from the SafetyTable[] array.
872 // Add the score to the evaluation, and also to ei.futilityMargin. The
873 // reason for adding the king safety score to the futility margin is
874 // that the king safety scores can sometimes be very big, and that
875 // capturing a single attacking piece can therefore result in a score
876 // change far bigger than the value of the captured piece.
877 Score v = apply_weight(make_score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
879 ei.value -= Sign[Us] * v;
881 if (Us == pos.side_to_move())
882 ei.futilityMargin += mg_value(v);
887 // evaluate_passed_pawns() evaluates the passed pawns of the given color
890 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
892 const Color Them = (Us == WHITE ? BLACK : WHITE);
895 Square ourKingSq = pos.king_square(Us);
896 Square theirKingSq = pos.king_square(Them);
897 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
901 Square s = pop_1st_bit(&b);
903 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
904 assert(pos.pawn_is_passed(Us, s));
906 int r = int(relative_rank(Us, s) - RANK_2);
907 int tr = Max(0, r * (r - 1));
909 // Base bonus based on rank
910 Value mbonus = Value(20 * tr);
911 Value ebonus = Value(10 + r * r * 10);
913 // Adjust bonus based on king proximity
916 Square blockSq = s + pawn_push(Us);
918 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
919 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
920 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
922 // If the pawn is free to advance, increase bonus
923 if (pos.square_is_empty(blockSq))
925 // There are no enemy pawns in the pawn's path
926 b2 = squares_in_front_of(Us, s);
928 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
930 // Squares attacked by us
931 b4 = b2 & ei.attacked_by(Us);
933 // Squares attacked or occupied by enemy pieces
934 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
936 // If there is an enemy rook or queen attacking the pawn from behind,
937 // add all X-ray attacks by the rook or queen.
938 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
939 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
942 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
943 if (b3 == EmptyBoardBB)
944 // No enemy attacks or pieces, huge bonus!
945 // Even bigger if we protect the pawn's path
946 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
948 // OK, there are enemy attacks or pieces (but not pawns). Are those
949 // squares which are attacked by the enemy also attacked by us ?
950 // If yes, big bonus (but smaller than when there are no enemy attacks),
951 // if no, somewhat smaller bonus.
952 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
954 // At last, add a small bonus when there are no *friendly* pieces
955 // in the pawn's path.
956 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
961 // If the pawn is supported by a friendly pawn, increase bonus
962 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
964 ebonus += Value(r * 20);
965 else if (pos.attacks_from<PAWN>(s, Them) & b2)
966 ebonus += Value(r * 12);
968 // If the other side has only a king, check whether the pawn is
970 if (pos.non_pawn_material(Them) == Value(0))
975 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
976 d = square_distance(s, qsq)
977 - square_distance(theirKingSq, qsq)
978 + (Us != pos.side_to_move());
982 int mtg = RANK_8 - relative_rank(Us, s);
983 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
986 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
994 // Rook pawns are a special case: They are sometimes worse, and
995 // sometimes better than other passed pawns. It is difficult to find
996 // good rules for determining whether they are good or bad. For now,
997 // we try the following: Increase the value for rook pawns if the
998 // other side has no pieces apart from a knight, and decrease the
999 // value if the other side has a rook or queen.
1000 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1002 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1003 && pos.piece_count(Them, KNIGHT) <= 1)
1004 ebonus += ebonus / 4;
1005 else if (pos.pieces(ROOK, QUEEN, Them))
1006 ebonus -= ebonus / 4;
1009 // Add the scores for this pawn to the middle game and endgame eval.
1010 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
1016 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1018 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1020 int movesToGo[2] = {0, 0};
1021 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1023 // Evaluate pawns for each color
1024 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1025 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1027 // Neither side has an unstoppable passed pawn?
1028 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1031 // Does only one side have an unstoppable passed pawn?
1032 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1034 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1035 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1038 { // Both sides have unstoppable pawns! Try to find out who queens
1039 // first. We begin by transforming 'movesToGo' to the number of
1040 // plies until the pawn queens for both sides.
1041 movesToGo[WHITE] *= 2;
1042 movesToGo[BLACK] *= 2;
1043 movesToGo[pos.side_to_move()]--;
1045 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1046 Color loserSide = opposite_color(winnerSide);
1048 // If one side queens at least three plies before the other, that side wins
1049 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1050 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1052 // If one side queens one ply before the other and checks the king or attacks
1053 // the undefended opponent's queening square, that side wins. To avoid cases
1054 // where the opponent's king could move somewhere before first pawn queens we
1055 // consider only free paths to queen for both pawns.
1056 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1057 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1059 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1061 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1062 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1064 Bitboard b = pos.occupied_squares();
1065 clear_bit(&b, pawnToGo[winnerSide]);
1066 clear_bit(&b, pawnToGo[loserSide]);
1067 b = queen_attacks_bb(winnerQSq, b);
1069 if ( (b & pos.pieces(KING, loserSide))
1070 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1071 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1077 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1078 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1081 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1083 assert(square_is_ok(s));
1084 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1086 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1087 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1089 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1090 && pos.see(s, b6) < 0
1091 && pos.see(s, b8) < 0)
1093 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1098 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1099 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1100 // black), and assigns a penalty if it is. This pattern can obviously
1101 // only occur in Chess960 games.
1103 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1105 Piece pawn = piece_of_color_and_type(us, PAWN);
1109 assert(square_is_ok(s));
1110 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1112 if (square_file(s) == FILE_A)
1114 b2 = relative_square(us, SQ_B2);
1115 b3 = relative_square(us, SQ_B3);
1116 c3 = relative_square(us, SQ_C3);
1120 b2 = relative_square(us, SQ_G2);
1121 b3 = relative_square(us, SQ_G3);
1122 c3 = relative_square(us, SQ_F3);
1125 if (pos.piece_on(b2) == pawn)
1129 if (!pos.square_is_empty(b3))
1130 penalty = 2 * TrappedBishopA1H1Penalty;
1131 else if (pos.piece_on(c3) == pawn)
1132 penalty = TrappedBishopA1H1Penalty;
1134 penalty = TrappedBishopA1H1Penalty / 2;
1136 ei.value -= Sign[us] * penalty;
1141 // evaluate_space() computes the space evaluation for a given side. The
1142 // space evaluation is a simple bonus based on the number of safe squares
1143 // available for minor pieces on the central four files on ranks 2--4. Safe
1144 // squares one, two or three squares behind a friendly pawn are counted
1145 // twice. Finally, the space bonus is scaled by a weight taken from the
1146 // material hash table.
1147 template<Color Us, bool HasPopCnt>
1148 void evaluate_space(const Position& pos, EvalInfo& ei) {
1150 const Color Them = (Us == WHITE ? BLACK : WHITE);
1152 // Find the safe squares for our pieces inside the area defined by
1153 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1154 // pawn, or if it is undefended and attacked by an enemy piece.
1156 Bitboard safeSquares = SpaceMask[Us]
1157 & ~pos.pieces(PAWN, Us)
1158 & ~ei.attacked_by(Them, PAWN)
1159 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1161 // Find all squares which are at most three squares behind some friendly
1163 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1164 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1165 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1167 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1168 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1170 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1174 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1176 inline Score apply_weight(Score v, Score w) {
1177 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1181 // scale_by_game_phase() interpolates between a middle game and an endgame
1182 // score, based on game phase. It also scales the return value by a
1183 // ScaleFactor array.
1185 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1187 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1188 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1189 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1191 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1193 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1194 return Value(result & ~(GrainSize - 1));
1198 // weight_option() computes the value of an evaluation weight, by combining
1199 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1201 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1203 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1205 // Convert to integer to prevent overflow
1206 int mg = mg_value(uciWeight);
1207 int eg = eg_value(uciWeight);
1209 mg = (mg * 0x100) / 100;
1210 eg = (eg * 0x100) / 100;
1211 mg = (mg * mg_value(internalWeight)) / 0x100;
1212 eg = (eg * eg_value(internalWeight)) / 0x100;
1213 return make_score(mg, eg);
1216 // init_safety() initizes the king safety evaluation, based on UCI
1217 // parameters. It is called from read_weights().
1219 void init_safety() {
1221 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1222 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1223 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1224 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1225 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1226 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1227 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1229 int maxSlope = get_option_value_int("King Safety Max Slope");
1230 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1231 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1232 double b = get_option_value_int("King Safety X Intercept");
1233 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1234 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1236 for (int i = 0; i < 100; i++)
1239 SafetyTable[i] = Value(0);
1241 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1243 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1246 for (int i = 0; i < 100; i++)
1248 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1249 for (int j = i + 1; j < 100; j++)
1250 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1252 if (SafetyTable[i] > Value(peak))
1253 SafetyTable[i] = Value(peak);