2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
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
228 const int QueenContactCheckBonus = 3;
229 const int DiscoveredCheckBonus = 3;
230 const int QueenCheckBonus = 2;
231 const int RookCheckBonus = 1;
232 const int BishopCheckBonus = 1;
233 const int KnightCheckBonus = 1;
235 // Scan for queen contact mates?
236 const bool QueenContactMates = true;
238 // Bonus for having a mate threat
239 const int MateThreatBonus = 3;
241 // InitKingDanger[] contains bonuses based on the position of the defending
243 const int InitKingDanger[64] = {
244 2, 0, 2, 5, 5, 2, 0, 2,
245 2, 2, 4, 8, 8, 4, 2, 2,
246 7, 10, 12, 12, 12, 12, 10, 7,
247 15, 15, 15, 15, 15, 15, 15, 15,
248 15, 15, 15, 15, 15, 15, 15, 15,
249 15, 15, 15, 15, 15, 15, 15, 15,
250 15, 15, 15, 15, 15, 15, 15, 15,
251 15, 15, 15, 15, 15, 15, 15, 15
254 // SafetyTable[] contains the actual king safety scores. It is initialized
256 Value SafetyTable[100];
258 // Pawn and material hash tables, indexed by the current thread id.
259 // Note that they will be initialized at 0 being global variables.
260 MaterialInfoTable* MaterialTable[MAX_THREADS];
261 PawnInfoTable* PawnTable[MAX_THREADS];
263 // Sizes of pawn and material hash tables
264 const int PawnTableSize = 16384;
265 const int MaterialTableSize = 1024;
267 // Function prototypes
268 template<bool HasPopCnt>
269 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
271 template<Color Us, bool HasPopCnt>
272 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
274 template<Color Us, bool HasPopCnt>
275 void evaluate_king(const Position& pos, EvalInfo& ei);
278 void evaluate_threats(const Position& pos, EvalInfo& ei);
280 template<Color Us, bool HasPopCnt>
281 void evaluate_space(const Position& pos, EvalInfo& ei);
284 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
286 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
287 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
288 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
289 inline Score apply_weight(Score v, Score weight);
290 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
291 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
300 /// evaluate() is the main evaluation function. It always computes two
301 /// values, an endgame score and a middle game score, and interpolates
302 /// between them based on the remaining material.
303 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
305 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
306 : do_evaluate<false>(pos, ei, threadID);
311 template<bool HasPopCnt>
312 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
315 ScaleFactor factor[2];
318 assert(threadID >= 0 && threadID < MAX_THREADS);
319 assert(!pos.is_check());
321 memset(&ei, 0, sizeof(EvalInfo));
323 // Initialize by reading the incrementally updated scores included in the
324 // position object (material + piece square tables)
325 ei.value = pos.value();
327 // Probe the material hash table
328 ei.mi = MaterialTable[threadID]->get_material_info(pos);
329 ei.value += ei.mi->material_value();
331 // If we have a specialized evaluation function for the current material
332 // configuration, call it and return
333 if (ei.mi->specialized_eval_exists())
334 return ei.mi->evaluate(pos);
336 // After get_material_info() call that modifies them
337 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
338 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
340 // Probe the pawn hash table
341 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
342 ei.value += apply_weight(ei.pi->pawns_value(), WeightPawnStructure);
344 // Initialize king attack bitboards and king attack zones for both sides
345 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
346 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
347 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
348 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
350 // Initialize pawn attack bitboards for both sides
351 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
352 b = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
354 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b)/2;
356 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
357 b = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
359 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b)/2;
362 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
363 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
365 // Kings. Kings are evaluated after all other pieces for both sides,
366 // because we need complete attack information for all pieces when computing
367 // the king safety evaluation.
368 evaluate_king<WHITE, HasPopCnt>(pos, ei);
369 evaluate_king<BLACK, HasPopCnt>(pos, ei);
371 // Evaluate tactical threats, we need full attack info including king
372 evaluate_threats<WHITE>(pos, ei);
373 evaluate_threats<BLACK>(pos, ei);
375 // Evaluate passed pawns, we need full attack info including king
376 evaluate_passed_pawns<WHITE>(pos, ei);
377 evaluate_passed_pawns<BLACK>(pos, ei);
379 // If one side has only a king, check whether exsists any unstoppable passed pawn
380 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
381 evaluate_unstoppable_pawns(pos, ei);
383 Phase phase = ei.mi->game_phase();
385 // Middle-game specific evaluation terms
386 if (phase > PHASE_ENDGAME)
388 // Pawn storms in positions with opposite castling
389 if ( square_file(pos.king_square(WHITE)) >= FILE_E
390 && square_file(pos.king_square(BLACK)) <= FILE_D)
392 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
394 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
395 && square_file(pos.king_square(BLACK)) >= FILE_E)
397 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
399 // Evaluate space for both sides
400 if (ei.mi->space_weight() > 0)
402 evaluate_space<WHITE, HasPopCnt>(pos, ei);
403 evaluate_space<BLACK, HasPopCnt>(pos, ei);
408 ei.value += apply_weight(ei.mobility, WeightMobility);
410 // If we don't already have an unusual scale factor, check for opposite
411 // colored bishop endgames, and use a lower scale for those
412 if ( phase < PHASE_MIDGAME
413 && pos.opposite_colored_bishops()
414 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
415 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
419 // Only the two bishops ?
420 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
421 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
423 // Check for KBP vs KB with only a single pawn that is almost
424 // certainly a draw or at least two pawns.
425 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
426 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
429 // Endgame with opposite-colored bishops, but also other pieces. Still
430 // a bit drawish, but not as drawish as with only the two bishops.
431 sf = ScaleFactor(50);
433 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
435 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
439 // Interpolate between the middle game and the endgame score
440 Color stm = pos.side_to_move();
442 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
444 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
449 /// init_eval() initializes various tables used by the evaluation function
451 void init_eval(int threads) {
453 assert(threads <= MAX_THREADS);
455 for (int i = 0; i < MAX_THREADS; i++)
460 delete MaterialTable[i];
462 MaterialTable[i] = NULL;
466 PawnTable[i] = new PawnInfoTable(PawnTableSize);
467 if (!MaterialTable[i])
468 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
473 /// quit_eval() releases heap-allocated memory at program termination
477 for (int i = 0; i < MAX_THREADS; i++)
480 delete MaterialTable[i];
482 MaterialTable[i] = NULL;
487 /// read_weights() reads evaluation weights from the corresponding UCI parameters
489 void read_weights(Color us) {
491 Color them = opposite_color(us);
493 WeightMobility = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightMobilityInternal);
494 WeightPawnStructure = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightPawnStructureInternal);
495 WeightPassedPawns = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightPassedPawnsInternal);
496 WeightSpace = weight_option("Space", "Space", WeightSpaceInternal);
497 WeightKingSafety[us] = weight_option("Cowardice", "Cowardice", WeightKingSafetyInternal);
498 WeightKingSafety[them] = weight_option("Aggressiveness", "Aggressiveness", WeightKingOppSafetyInternal);
500 // If running in analysis mode, make sure we use symmetrical king safety. We do this
501 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
502 if (get_option_value_bool("UCI_AnalyseMode"))
504 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
505 WeightKingSafety[them] = WeightKingSafety[us];
513 // evaluate_outposts() evaluates bishop and knight outposts squares
515 template<PieceType Piece, Color Us>
516 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
518 const Color Them = (Us == WHITE ? BLACK : WHITE);
520 // Initial bonus based on square
521 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
522 : KnightOutpostBonus[relative_square(Us, s)]);
524 // Increase bonus if supported by pawn, especially if the opponent has
525 // no minor piece which can exchange the outpost piece
526 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
528 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
529 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
530 bonus += bonus + bonus / 2;
534 ei.value += Sign[Us] * make_score(bonus, bonus);
538 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
540 template<PieceType Piece, Color Us, bool HasPopCnt>
541 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
548 const Color Them = (Us == WHITE ? BLACK : WHITE);
549 const Square* ptr = pos.piece_list_begin(Us, Piece);
551 while ((s = *ptr++) != SQ_NONE)
553 // Find attacked squares, including x-ray attacks for bishops and rooks
554 if (Piece == KNIGHT || Piece == QUEEN)
555 b = pos.attacks_from<Piece>(s);
556 else if (Piece == BISHOP)
557 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
558 else if (Piece == ROOK)
559 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
563 // Update attack info
564 ei.attackedBy[Us][Piece] |= b;
567 if (b & ei.kingZone[Us])
569 ei.kingAttackersCount[Us]++;
570 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
571 Bitboard bb = (b & ei.attackedBy[Them][KING]);
573 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
577 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
578 : count_1s<HasPopCnt>(b & no_mob_area));
580 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
582 // Decrease score if we are attacked by an enemy pawn. Remaining part
583 // of threat evaluation must be done later when we have full attack info.
584 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
585 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
587 // Bishop and knight outposts squares
588 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
589 evaluate_outposts<Piece, Us>(pos, ei, s);
591 // Special patterns: trapped bishops on a7/h7/a2/h2
592 // and trapped bishops on a1/h1/a8/h8 in Chess960.
595 if (bit_is_set(MaskA7H7[Us], s))
596 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
598 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
599 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
602 // Queen or rook on 7th rank
603 if ( (Piece == ROOK || Piece == QUEEN)
604 && relative_rank(Us, s) == RANK_7
605 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
607 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
610 // Special extra evaluation for rooks
613 // Open and half-open files
615 if (ei.pi->file_is_half_open(Us, f))
617 if (ei.pi->file_is_half_open(Them, f))
618 ei.value += Sign[Us] * RookOpenFileBonus;
620 ei.value += Sign[Us] * RookHalfOpenFileBonus;
623 // Penalize rooks which are trapped inside a king. Penalize more if
624 // king has lost right to castle.
625 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
628 ksq = pos.king_square(Us);
630 if ( square_file(ksq) >= FILE_E
631 && square_file(s) > square_file(ksq)
632 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
634 // Is there a half-open file between the king and the edge of the board?
635 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
636 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
637 : (TrappedRookPenalty - mob * 16), 0);
639 else if ( square_file(ksq) <= FILE_D
640 && square_file(s) < square_file(ksq)
641 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
643 // Is there a half-open file between the king and the edge of the board?
644 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
645 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
646 : (TrappedRookPenalty - mob * 16), 0);
653 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
654 // and the type of attacked one.
657 void evaluate_threats(const Position& pos, EvalInfo& ei) {
659 const Color Them = (Us == WHITE ? BLACK : WHITE);
662 Score bonus = make_score(0, 0);
664 // Enemy pieces not defended by a pawn and under our attack
665 Bitboard weakEnemies = pos.pieces_of_color(Them)
666 & ~ei.attackedBy[Them][PAWN]
667 & ei.attackedBy[Us][0];
671 // Add bonus according to type of attacked enemy pieces and to the
672 // type of attacking piece, from knights to queens. Kings are not
673 // considered because are already special handled in king evaluation.
674 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
676 b = ei.attackedBy[Us][pt1] & weakEnemies;
678 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
679 if (b & pos.pieces(pt2))
680 bonus += ThreatBonus[pt1][pt2];
682 ei.value += Sign[Us] * bonus;
686 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
687 // pieces of a given color.
689 template<Color Us, bool HasPopCnt>
690 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
692 const Color Them = (Us == WHITE ? BLACK : WHITE);
694 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
695 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
697 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
698 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
699 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
700 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
702 // Sum up all attacked squares
703 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
704 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
705 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
709 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
711 template<Color Us, bool HasPopCnt>
712 void evaluate_king(const Position& pos, EvalInfo& ei) {
714 const Color Them = (Us == WHITE ? BLACK : WHITE);
716 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
719 int attackUnits, count, shelter = 0;
720 const Square s = pos.king_square(Us);
723 if (relative_rank(Us, s) <= RANK_4)
725 shelter = ei.pi->get_king_shelter(pos, Us, s);
726 ei.value += Sign[Us] * make_score(shelter, 0);
729 // King safety. This is quite complicated, and is almost certainly far
730 // from optimally tuned.
731 if ( pos.piece_count(Them, QUEEN) >= 1
732 && ei.kingAttackersCount[Them] >= 2
733 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
734 && ei.kingAdjacentZoneAttacksCount[Them])
736 // Is it the attackers turn to move?
737 sente = (Them == pos.side_to_move());
739 // Find the attacked squares around the king which has no defenders
740 // apart from the king itself
741 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
742 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
743 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
744 | ei.attacked_by(Us, QUEEN));
746 // Initialize the 'attackUnits' variable, which is used later on as an
747 // index to the SafetyTable[] array. The initial value is based on the
748 // number and types of the attacking pieces, the number of attacked and
749 // undefended squares around the king, the square of the king, and the
750 // quality of the pawn shelter.
751 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
752 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
753 + InitKingDanger[relative_square(Us, s)]
756 // Analyse safe queen contact checks
757 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
760 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
761 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
763 b &= attackedByOthers;
765 // Squares attacked by the queen and supported by another enemy piece and
766 // not defended by other pieces but our king.
769 // The bitboard b now contains the squares available for safe queen
771 count = count_1s_max_15<HasPopCnt>(b);
772 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
774 // Is there a mate threat?
775 if (QueenContactMates && !pos.is_check())
777 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
778 occ = pos.occupied_squares();
781 to = pop_1st_bit(&b);
783 // Do we have escape squares from queen contact check attack ?
784 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
786 // We have a mate, unless the queen is pinned or there
787 // is an X-ray attack through the queen.
788 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
790 from = pos.piece_list(Them, QUEEN, i);
791 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
792 && !bit_is_set(pos.pinned_pieces(Them), from)
793 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
794 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
796 // Set the mate threat move
797 ei.mateThreat[Them] = make_move(from, to);
805 // Analyse safe distance checks
806 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
808 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
810 b = pos.attacks_from<ROOK>(s) & safe;
813 b2 = b & ei.attacked_by(Them, QUEEN);
815 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
818 b2 = b & ei.attacked_by(Them, ROOK);
820 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
822 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
824 b = pos.attacks_from<BISHOP>(s) & safe;
827 b2 = b & ei.attacked_by(Them, QUEEN);
829 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
832 b2 = b & ei.attacked_by(Them, BISHOP);
834 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
836 if (KnightCheckBonus > 0)
838 b = pos.attacks_from<KNIGHT>(s) & safe;
841 b2 = b & ei.attacked_by(Them, KNIGHT);
843 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
846 // Analyse discovered checks (only for non-pawns right now, consider
847 // adding pawns later).
848 if (DiscoveredCheckBonus)
850 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
852 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
855 // Has a mate threat been found? We don't do anything here if the
856 // side with the mating move is the side to move, because in that
857 // case the mating side will get a huge bonus at the end of the main
858 // evaluation function instead.
859 if (ei.mateThreat[Them] != MOVE_NONE)
860 attackUnits += MateThreatBonus;
862 // Ensure that attackUnits is between 0 and 99, in order to avoid array
863 // out of bounds errors.
864 attackUnits = Min(99, Max(0, attackUnits));
866 // Finally, extract the king safety score from the SafetyTable[] array.
867 // Add the score to the evaluation, and also to ei.futilityMargin. The
868 // reason for adding the king safety score to the futility margin is
869 // that the king safety scores can sometimes be very big, and that
870 // capturing a single attacking piece can therefore result in a score
871 // change far bigger than the value of the captured piece.
872 Score v = apply_weight(make_score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
873 ei.value -= Sign[Us] * v;
874 ei.futilityMargin[Us] += mg_value(v);
879 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
882 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
884 const Color Them = (Us == WHITE ? BLACK : WHITE);
886 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us);
890 Square s = pop_1st_bit(&b);
892 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
893 assert(pos.pawn_is_passed(Us, s));
895 int r = int(relative_rank(Us, s) - RANK_2);
896 int tr = Max(0, r * (r - 1));
898 // Base bonus based on rank
899 Value mbonus = Value(20 * tr);
900 Value ebonus = Value(10 + r * r * 10);
902 // Adjust bonus based on king proximity
905 Square blockSq = s + pawn_push(Us);
907 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * tr);
908 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * tr);
909 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
911 // If the pawn is free to advance, increase bonus
912 if (pos.square_is_empty(blockSq))
914 // There are no enemy pawns in the pawn's path
915 Bitboard b2 = squares_in_front_of(Us, s);
917 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
919 // Squares attacked by us
920 Bitboard b4 = b2 & ei.attacked_by(Us);
922 // Squares attacked or occupied by enemy pieces
923 Bitboard b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
925 // If there is an enemy rook or queen attacking the pawn from behind,
926 // add all X-ray attacks by the rook or queen.
927 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
928 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
931 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
932 if (b3 == EmptyBoardBB)
933 // No enemy attacks or pieces, huge bonus!
934 // Even bigger if we protect the pawn's path
935 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
937 // OK, there are enemy attacks or pieces (but not pawns). Are those
938 // squares which are attacked by the enemy also attacked by us ?
939 // If yes, big bonus (but smaller than when there are no enemy attacks),
940 // if no, somewhat smaller bonus.
941 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
943 // At last, add a small bonus when there are no *friendly* pieces
944 // in the pawn's path.
945 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
950 // If the pawn is supported by a friendly pawn, increase bonus
951 Bitboard b1 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
953 ebonus += Value(r * 20);
954 else if (pos.attacks_from<PAWN>(s, Them) & b1)
955 ebonus += Value(r * 12);
957 // Rook pawns are a special case: They are sometimes worse, and
958 // sometimes better than other passed pawns. It is difficult to find
959 // good rules for determining whether they are good or bad. For now,
960 // we try the following: Increase the value for rook pawns if the
961 // other side has no pieces apart from a knight, and decrease the
962 // value if the other side has a rook or queen.
963 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
965 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
966 && pos.piece_count(Them, KNIGHT) <= 1)
967 ebonus += ebonus / 4;
968 else if (pos.pieces(ROOK, QUEEN, Them))
969 ebonus -= ebonus / 4;
972 // Add the scores for this pawn to the middle game and endgame eval.
973 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
979 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides
981 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
983 int movesToGo[2] = {0, 0};
984 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
986 for (Color c = WHITE; c <= BLACK; c++)
988 // Skip evaluation if other side has non-pawn pieces
989 if (pos.non_pawn_material(opposite_color(c)))
992 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(c);
996 Square s = pop_1st_bit(&b);
997 Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8));
998 int d = square_distance(s, queeningSquare)
999 - square_distance(pos.king_square(opposite_color(c)), queeningSquare)
1000 + int(c != pos.side_to_move());
1004 int mtg = RANK_8 - relative_rank(c, s);
1005 int blockerCount = count_1s_max_15(squares_in_front_of(c, s) & pos.occupied_squares());
1006 mtg += blockerCount;
1008 if (d < 0 && (!movesToGo[c] || movesToGo[c] > mtg))
1017 // Neither side has an unstoppable passed pawn?
1018 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1021 // Does only one side have an unstoppable passed pawn?
1022 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1024 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1025 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1028 { // Both sides have unstoppable pawns! Try to find out who queens
1029 // first. We begin by transforming 'movesToGo' to the number of
1030 // plies until the pawn queens for both sides.
1031 movesToGo[WHITE] *= 2;
1032 movesToGo[BLACK] *= 2;
1033 movesToGo[pos.side_to_move()]--;
1035 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1036 Color loserSide = opposite_color(winnerSide);
1038 // If one side queens at least three plies before the other, that side wins
1039 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1040 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1042 // If one side queens one ply before the other and checks the king or attacks
1043 // the undefended opponent's queening square, that side wins. To avoid cases
1044 // where the opponent's king could move somewhere before first pawn queens we
1045 // consider only free paths to queen for both pawns.
1046 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1047 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1049 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1051 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1052 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1054 Bitboard b = pos.occupied_squares();
1055 clear_bit(&b, pawnToGo[winnerSide]);
1056 clear_bit(&b, pawnToGo[loserSide]);
1057 b = queen_attacks_bb(winnerQSq, b);
1059 if ( (b & pos.pieces(KING, loserSide))
1060 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1061 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1067 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1068 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1071 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1073 assert(square_is_ok(s));
1074 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1076 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1077 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1079 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1080 && pos.see(s, b6) < 0
1081 && pos.see(s, b8) < 0)
1083 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1088 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1089 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1090 // black), and assigns a penalty if it is. This pattern can obviously
1091 // only occur in Chess960 games.
1093 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1095 Piece pawn = piece_of_color_and_type(us, PAWN);
1099 assert(square_is_ok(s));
1100 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1102 if (square_file(s) == FILE_A)
1104 b2 = relative_square(us, SQ_B2);
1105 b3 = relative_square(us, SQ_B3);
1106 c3 = relative_square(us, SQ_C3);
1110 b2 = relative_square(us, SQ_G2);
1111 b3 = relative_square(us, SQ_G3);
1112 c3 = relative_square(us, SQ_F3);
1115 if (pos.piece_on(b2) == pawn)
1119 if (!pos.square_is_empty(b3))
1120 penalty = 2 * TrappedBishopA1H1Penalty;
1121 else if (pos.piece_on(c3) == pawn)
1122 penalty = TrappedBishopA1H1Penalty;
1124 penalty = TrappedBishopA1H1Penalty / 2;
1126 ei.value -= Sign[us] * penalty;
1131 // evaluate_space() computes the space evaluation for a given side. The
1132 // space evaluation is a simple bonus based on the number of safe squares
1133 // available for minor pieces on the central four files on ranks 2--4. Safe
1134 // squares one, two or three squares behind a friendly pawn are counted
1135 // twice. Finally, the space bonus is scaled by a weight taken from the
1136 // material hash table.
1137 template<Color Us, bool HasPopCnt>
1138 void evaluate_space(const Position& pos, EvalInfo& ei) {
1140 const Color Them = (Us == WHITE ? BLACK : WHITE);
1142 // Find the safe squares for our pieces inside the area defined by
1143 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1144 // pawn, or if it is undefended and attacked by an enemy piece.
1146 Bitboard safeSquares = SpaceMask[Us]
1147 & ~pos.pieces(PAWN, Us)
1148 & ~ei.attacked_by(Them, PAWN)
1149 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1151 // Find all squares which are at most three squares behind some friendly
1153 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1154 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1155 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1157 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1158 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1160 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1164 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1166 inline Score apply_weight(Score v, Score w) {
1167 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1171 // scale_by_game_phase() interpolates between a middle game and an endgame
1172 // score, based on game phase. It also scales the return value by a
1173 // ScaleFactor array.
1175 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1177 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1178 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1179 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1181 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1183 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1184 return Value(result & ~(GrainSize - 1));
1188 // weight_option() computes the value of an evaluation weight, by combining
1189 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1191 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1193 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1195 // Convert to integer to prevent overflow
1196 int mg = mg_value(uciWeight);
1197 int eg = eg_value(uciWeight);
1199 mg = (mg * 0x100) / 100;
1200 eg = (eg * 0x100) / 100;
1201 mg = (mg * mg_value(internalWeight)) / 0x100;
1202 eg = (eg * eg_value(internalWeight)) / 0x100;
1203 return make_score(mg, eg);
1206 // init_safety() initizes the king safety evaluation, based on UCI
1207 // parameters. It is called from read_weights().
1209 void init_safety() {
1216 for (int i = 0; i < 100; i++)
1219 SafetyTable[i] = Value(0);
1221 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1224 for (int i = 1; i < 100; i++)
1226 if (SafetyTable[i] - SafetyTable[i - 1] > maxSlope)
1227 SafetyTable[i] = SafetyTable[i - 1] + Value(maxSlope);
1229 if (SafetyTable[i] > Value(peak))
1230 SafetyTable[i] = Value(peak);