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[color][] contains the actual king safety weighted scores
255 Score SafetyTable[2][128];
257 // Pawn and material hash tables, indexed by the current thread id.
258 // Note that they will be initialized at 0 being global variables.
259 MaterialInfoTable* MaterialTable[MAX_THREADS];
260 PawnInfoTable* PawnTable[MAX_THREADS];
262 // Sizes of pawn and material hash tables
263 const int PawnTableSize = 16384;
264 const int MaterialTableSize = 1024;
266 // Function prototypes
267 template<bool HasPopCnt>
268 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
270 template<Color Us, bool HasPopCnt>
271 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
273 template<Color Us, bool HasPopCnt>
274 void evaluate_king(const Position& pos, EvalInfo& ei);
277 void evaluate_threats(const Position& pos, EvalInfo& ei);
279 template<Color Us, bool HasPopCnt>
280 void evaluate_space(const Position& pos, EvalInfo& ei);
283 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
285 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
286 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
287 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
288 inline Score apply_weight(Score v, Score weight);
289 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
290 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
299 /// evaluate() is the main evaluation function. It always computes two
300 /// values, an endgame score and a middle game score, and interpolates
301 /// between them based on the remaining material.
302 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
304 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
305 : do_evaluate<false>(pos, ei, threadID);
310 template<bool HasPopCnt>
311 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
314 ScaleFactor factor[2];
317 assert(threadID >= 0 && threadID < MAX_THREADS);
318 assert(!pos.is_check());
320 memset(&ei, 0, sizeof(EvalInfo));
322 // Initialize by reading the incrementally updated scores included in the
323 // position object (material + piece square tables)
324 ei.value = pos.value();
326 // Probe the material hash table
327 ei.mi = MaterialTable[threadID]->get_material_info(pos);
328 ei.value += ei.mi->material_value();
330 // If we have a specialized evaluation function for the current material
331 // configuration, call it and return
332 if (ei.mi->specialized_eval_exists())
333 return ei.mi->evaluate(pos);
335 // After get_material_info() call that modifies them
336 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
337 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
339 // Probe the pawn hash table
340 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
341 ei.value += apply_weight(ei.pi->pawns_value(), WeightPawnStructure);
343 // Initialize king attack bitboards and king attack zones for both sides
344 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
345 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
346 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
347 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
349 // Initialize pawn attack bitboards for both sides
350 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
351 b = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
353 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b)/2;
355 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
356 b = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
358 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b)/2;
361 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
362 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
364 // Kings. Kings are evaluated after all other pieces for both sides,
365 // because we need complete attack information for all pieces when computing
366 // the king safety evaluation.
367 evaluate_king<WHITE, HasPopCnt>(pos, ei);
368 evaluate_king<BLACK, HasPopCnt>(pos, ei);
370 // Evaluate tactical threats, we need full attack info including king
371 evaluate_threats<WHITE>(pos, ei);
372 evaluate_threats<BLACK>(pos, ei);
374 // Evaluate passed pawns, we need full attack info including king
375 evaluate_passed_pawns<WHITE>(pos, ei);
376 evaluate_passed_pawns<BLACK>(pos, ei);
378 // If one side has only a king, check whether exsists any unstoppable passed pawn
379 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
380 evaluate_unstoppable_pawns(pos, ei);
382 Phase phase = ei.mi->game_phase();
384 // Middle-game specific evaluation terms
385 if (phase > PHASE_ENDGAME)
387 // Pawn storms in positions with opposite castling
388 if ( square_file(pos.king_square(WHITE)) >= FILE_E
389 && square_file(pos.king_square(BLACK)) <= FILE_D)
391 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
393 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
394 && square_file(pos.king_square(BLACK)) >= FILE_E)
396 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
398 // Evaluate space for both sides
399 if (ei.mi->space_weight() > 0)
401 evaluate_space<WHITE, HasPopCnt>(pos, ei);
402 evaluate_space<BLACK, HasPopCnt>(pos, ei);
407 ei.value += apply_weight(ei.mobility, WeightMobility);
409 // If we don't already have an unusual scale factor, check for opposite
410 // colored bishop endgames, and use a lower scale for those
411 if ( phase < PHASE_MIDGAME
412 && pos.opposite_colored_bishops()
413 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
414 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
418 // Only the two bishops ?
419 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
420 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
422 // Check for KBP vs KB with only a single pawn that is almost
423 // certainly a draw or at least two pawns.
424 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
425 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
428 // Endgame with opposite-colored bishops, but also other pieces. Still
429 // a bit drawish, but not as drawish as with only the two bishops.
430 sf = ScaleFactor(50);
432 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
434 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
438 // Interpolate between the middle game and the endgame score
439 Color stm = pos.side_to_move();
441 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
443 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
448 /// init_eval() initializes various tables used by the evaluation function
450 void init_eval(int threads) {
452 assert(threads <= MAX_THREADS);
454 for (int i = 0; i < MAX_THREADS; i++)
459 delete MaterialTable[i];
461 MaterialTable[i] = NULL;
465 PawnTable[i] = new PawnInfoTable(PawnTableSize);
466 if (!MaterialTable[i])
467 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
472 /// quit_eval() releases heap-allocated memory at program termination
476 for (int i = 0; i < MAX_THREADS; i++)
479 delete MaterialTable[i];
481 MaterialTable[i] = NULL;
486 /// read_weights() reads evaluation weights from the corresponding UCI parameters
488 void read_weights(Color us) {
490 Color them = opposite_color(us);
492 WeightMobility = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightMobilityInternal);
493 WeightPawnStructure = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightPawnStructureInternal);
494 WeightPassedPawns = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightPassedPawnsInternal);
495 WeightSpace = weight_option("Space", "Space", WeightSpaceInternal);
496 WeightKingSafety[us] = weight_option("Cowardice", "Cowardice", WeightKingSafetyInternal);
497 WeightKingSafety[them] = weight_option("Aggressiveness", "Aggressiveness", WeightKingOppSafetyInternal);
499 // If running in analysis mode, make sure we use symmetrical king safety. We do this
500 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
501 if (get_option_value_bool("UCI_AnalyseMode"))
503 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
504 WeightKingSafety[them] = WeightKingSafety[us];
512 // evaluate_outposts() evaluates bishop and knight outposts squares
514 template<PieceType Piece, Color Us>
515 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
517 const Color Them = (Us == WHITE ? BLACK : WHITE);
519 // Initial bonus based on square
520 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
521 : KnightOutpostBonus[relative_square(Us, s)]);
523 // Increase bonus if supported by pawn, especially if the opponent has
524 // no minor piece which can exchange the outpost piece
525 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
527 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
528 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
529 bonus += bonus + bonus / 2;
533 ei.value += Sign[Us] * make_score(bonus, bonus);
537 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
539 template<PieceType Piece, Color Us, bool HasPopCnt>
540 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
547 const Color Them = (Us == WHITE ? BLACK : WHITE);
548 const Square* ptr = pos.piece_list_begin(Us, Piece);
550 while ((s = *ptr++) != SQ_NONE)
552 // Find attacked squares, including x-ray attacks for bishops and rooks
553 if (Piece == KNIGHT || Piece == QUEEN)
554 b = pos.attacks_from<Piece>(s);
555 else if (Piece == BISHOP)
556 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
557 else if (Piece == ROOK)
558 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
562 // Update attack info
563 ei.attackedBy[Us][Piece] |= b;
566 if (b & ei.kingZone[Us])
568 ei.kingAttackersCount[Us]++;
569 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
570 Bitboard bb = (b & ei.attackedBy[Them][KING]);
572 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
576 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
577 : count_1s<HasPopCnt>(b & no_mob_area));
579 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
581 // Decrease score if we are attacked by an enemy pawn. Remaining part
582 // of threat evaluation must be done later when we have full attack info.
583 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
584 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
586 // Bishop and knight outposts squares
587 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
588 evaluate_outposts<Piece, Us>(pos, ei, s);
590 // Special patterns: trapped bishops on a7/h7/a2/h2
591 // and trapped bishops on a1/h1/a8/h8 in Chess960.
594 if (bit_is_set(MaskA7H7[Us], s))
595 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
597 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
598 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
601 // Queen or rook on 7th rank
602 if ( (Piece == ROOK || Piece == QUEEN)
603 && relative_rank(Us, s) == RANK_7
604 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
606 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
609 // Special extra evaluation for rooks
612 // Open and half-open files
614 if (ei.pi->file_is_half_open(Us, f))
616 if (ei.pi->file_is_half_open(Them, f))
617 ei.value += Sign[Us] * RookOpenFileBonus;
619 ei.value += Sign[Us] * RookHalfOpenFileBonus;
622 // Penalize rooks which are trapped inside a king. Penalize more if
623 // king has lost right to castle.
624 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
627 ksq = pos.king_square(Us);
629 if ( square_file(ksq) >= FILE_E
630 && square_file(s) > square_file(ksq)
631 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
633 // Is there a half-open file between the king and the edge of the board?
634 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
635 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
636 : (TrappedRookPenalty - mob * 16), 0);
638 else if ( square_file(ksq) <= FILE_D
639 && square_file(s) < square_file(ksq)
640 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
642 // Is there a half-open file between the king and the edge of the board?
643 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
644 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
645 : (TrappedRookPenalty - mob * 16), 0);
652 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
653 // and the type of attacked one.
656 void evaluate_threats(const Position& pos, EvalInfo& ei) {
658 const Color Them = (Us == WHITE ? BLACK : WHITE);
661 Score bonus = make_score(0, 0);
663 // Enemy pieces not defended by a pawn and under our attack
664 Bitboard weakEnemies = pos.pieces_of_color(Them)
665 & ~ei.attackedBy[Them][PAWN]
666 & ei.attackedBy[Us][0];
670 // Add bonus according to type of attacked enemy pieces and to the
671 // type of attacking piece, from knights to queens. Kings are not
672 // considered because are already special handled in king evaluation.
673 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
675 b = ei.attackedBy[Us][pt1] & weakEnemies;
677 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
678 if (b & pos.pieces(pt2))
679 bonus += ThreatBonus[pt1][pt2];
681 ei.value += Sign[Us] * bonus;
685 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
686 // pieces of a given color.
688 template<Color Us, bool HasPopCnt>
689 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
691 const Color Them = (Us == WHITE ? BLACK : WHITE);
693 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
694 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
696 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
697 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
698 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
699 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
701 // Sum up all attacked squares
702 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
703 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
704 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
708 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
710 template<Color Us, bool HasPopCnt>
711 void evaluate_king(const Position& pos, EvalInfo& ei) {
713 const Color Them = (Us == WHITE ? BLACK : WHITE);
715 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
718 int attackUnits, count, shelter = 0;
719 const Square s = pos.king_square(Us);
722 if (relative_rank(Us, s) <= RANK_4)
724 shelter = ei.pi->get_king_shelter(pos, Us, s);
725 ei.value += Sign[Us] * make_score(shelter, 0);
728 // King safety. This is quite complicated, and is almost certainly far
729 // from optimally tuned.
730 if ( pos.piece_count(Them, QUEEN) >= 1
731 && ei.kingAttackersCount[Them] >= 2
732 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
733 && ei.kingAdjacentZoneAttacksCount[Them])
735 // Is it the attackers turn to move?
736 sente = (Them == pos.side_to_move());
738 // Find the attacked squares around the king which has no defenders
739 // apart from the king itself
740 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
741 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
742 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
743 | ei.attacked_by(Us, QUEEN));
745 // Initialize the 'attackUnits' variable, which is used later on as an
746 // index to the SafetyTable[] array. The initial value is based on the
747 // number and types of the attacking pieces, the number of attacked and
748 // undefended squares around the king, the square of the king, and the
749 // quality of the pawn shelter.
750 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
751 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
752 + InitKingDanger[relative_square(Us, s)]
755 // Analyse safe queen contact checks
756 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
759 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
760 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
762 b &= attackedByOthers;
764 // Squares attacked by the queen and supported by another enemy piece and
765 // not defended by other pieces but our king.
768 // The bitboard b now contains the squares available for safe queen
770 count = count_1s_max_15<HasPopCnt>(b);
771 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
773 // Is there a mate threat?
774 if (QueenContactMates && !pos.is_check())
776 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
777 occ = pos.occupied_squares();
780 to = pop_1st_bit(&b);
782 // Do we have escape squares from queen contact check attack ?
783 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
785 // We have a mate, unless the queen is pinned or there
786 // is an X-ray attack through the queen.
787 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
789 from = pos.piece_list(Them, QUEEN, i);
790 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
791 && !bit_is_set(pos.pinned_pieces(Them), from)
792 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
793 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
795 // Set the mate threat move
796 ei.mateThreat[Them] = make_move(from, to);
804 // Analyse safe distance checks
805 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
807 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
809 b = pos.attacks_from<ROOK>(s) & safe;
812 b2 = b & ei.attacked_by(Them, QUEEN);
814 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
817 b2 = b & ei.attacked_by(Them, ROOK);
819 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
821 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
823 b = pos.attacks_from<BISHOP>(s) & safe;
826 b2 = b & ei.attacked_by(Them, QUEEN);
828 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
831 b2 = b & ei.attacked_by(Them, BISHOP);
833 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
835 if (KnightCheckBonus > 0)
837 b = pos.attacks_from<KNIGHT>(s) & safe;
840 b2 = b & ei.attacked_by(Them, KNIGHT);
842 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
845 // Analyse discovered checks (only for non-pawns right now, consider
846 // adding pawns later).
847 if (DiscoveredCheckBonus)
849 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
851 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
854 // Has a mate threat been found? We don't do anything here if the
855 // side with the mating move is the side to move, because in that
856 // case the mating side will get a huge bonus at the end of the main
857 // evaluation function instead.
858 if (ei.mateThreat[Them] != MOVE_NONE)
859 attackUnits += MateThreatBonus;
861 // Ensure that attackUnits is between 0 and 99, in order to avoid array
862 // out of bounds errors.
863 attackUnits = Min(99, Max(0, attackUnits));
865 // Finally, extract the king safety score from the SafetyTable[] array.
866 // Add the score to the evaluation, and also to ei.futilityMargin. The
867 // reason for adding the king safety score to the futility margin is
868 // that the king safety scores can sometimes be very big, and that
869 // capturing a single attacking piece can therefore result in a score
870 // change far bigger than the value of the captured piece.
871 ei.value -= Sign[Us] * SafetyTable[Us][attackUnits];
872 ei.futilityMargin[Us] += mg_value(SafetyTable[Us][attackUnits]);
877 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
880 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
882 const Color Them = (Us == WHITE ? BLACK : WHITE);
884 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us);
888 Square s = pop_1st_bit(&b);
890 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
891 assert(pos.pawn_is_passed(Us, s));
893 int r = int(relative_rank(Us, s) - RANK_2);
894 int tr = Max(0, r * (r - 1));
896 // Base bonus based on rank
897 Value mbonus = Value(20 * tr);
898 Value ebonus = Value(10 + r * r * 10);
900 // Adjust bonus based on king proximity
903 Square blockSq = s + pawn_push(Us);
905 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * tr);
906 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * tr);
907 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
909 // If the pawn is free to advance, increase bonus
910 if (pos.square_is_empty(blockSq))
912 // There are no enemy pawns in the pawn's path
913 Bitboard b2 = squares_in_front_of(Us, s);
915 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
917 // Squares attacked by us
918 Bitboard b4 = b2 & ei.attacked_by(Us);
920 // Squares attacked or occupied by enemy pieces
921 Bitboard b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
923 // If there is an enemy rook or queen attacking the pawn from behind,
924 // add all X-ray attacks by the rook or queen.
925 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
926 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
929 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
930 if (b3 == EmptyBoardBB)
931 // No enemy attacks or pieces, huge bonus!
932 // Even bigger if we protect the pawn's path
933 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
935 // OK, there are enemy attacks or pieces (but not pawns). Are those
936 // squares which are attacked by the enemy also attacked by us ?
937 // If yes, big bonus (but smaller than when there are no enemy attacks),
938 // if no, somewhat smaller bonus.
939 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
941 // At last, add a small bonus when there are no *friendly* pieces
942 // in the pawn's path.
943 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
948 // If the pawn is supported by a friendly pawn, increase bonus
949 Bitboard b1 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
951 ebonus += Value(r * 20);
952 else if (pos.attacks_from<PAWN>(s, Them) & b1)
953 ebonus += Value(r * 12);
955 // Rook pawns are a special case: They are sometimes worse, and
956 // sometimes better than other passed pawns. It is difficult to find
957 // good rules for determining whether they are good or bad. For now,
958 // we try the following: Increase the value for rook pawns if the
959 // other side has no pieces apart from a knight, and decrease the
960 // value if the other side has a rook or queen.
961 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
963 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
964 && pos.piece_count(Them, KNIGHT) <= 1)
965 ebonus += ebonus / 4;
966 else if (pos.pieces(ROOK, QUEEN, Them))
967 ebonus -= ebonus / 4;
970 // Add the scores for this pawn to the middle game and endgame eval.
971 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
977 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides
979 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
981 int movesToGo[2] = {0, 0};
982 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
984 for (Color c = WHITE; c <= BLACK; c++)
986 // Skip evaluation if other side has non-pawn pieces
987 if (pos.non_pawn_material(opposite_color(c)))
990 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(c);
994 Square s = pop_1st_bit(&b);
995 Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8));
996 int d = square_distance(s, queeningSquare)
997 - square_distance(pos.king_square(opposite_color(c)), queeningSquare)
998 + int(c != pos.side_to_move());
1002 int mtg = RANK_8 - relative_rank(c, s);
1003 int blockerCount = count_1s_max_15(squares_in_front_of(c, s) & pos.occupied_squares());
1004 mtg += blockerCount;
1006 if (d < 0 && (!movesToGo[c] || movesToGo[c] > mtg))
1015 // Neither side has an unstoppable passed pawn?
1016 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1019 // Does only one side have an unstoppable passed pawn?
1020 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1022 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1023 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1026 { // Both sides have unstoppable pawns! Try to find out who queens
1027 // first. We begin by transforming 'movesToGo' to the number of
1028 // plies until the pawn queens for both sides.
1029 movesToGo[WHITE] *= 2;
1030 movesToGo[BLACK] *= 2;
1031 movesToGo[pos.side_to_move()]--;
1033 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1034 Color loserSide = opposite_color(winnerSide);
1036 // If one side queens at least three plies before the other, that side wins
1037 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1038 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1040 // If one side queens one ply before the other and checks the king or attacks
1041 // the undefended opponent's queening square, that side wins. To avoid cases
1042 // where the opponent's king could move somewhere before first pawn queens we
1043 // consider only free paths to queen for both pawns.
1044 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1045 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1047 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1049 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1050 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1052 Bitboard b = pos.occupied_squares();
1053 clear_bit(&b, pawnToGo[winnerSide]);
1054 clear_bit(&b, pawnToGo[loserSide]);
1055 b = queen_attacks_bb(winnerQSq, b);
1057 if ( (b & pos.pieces(KING, loserSide))
1058 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1059 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1065 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1066 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1069 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1071 assert(square_is_ok(s));
1072 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1074 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1075 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1077 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1078 && pos.see(s, b6) < 0
1079 && pos.see(s, b8) < 0)
1081 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1086 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1087 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1088 // black), and assigns a penalty if it is. This pattern can obviously
1089 // only occur in Chess960 games.
1091 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1093 Piece pawn = piece_of_color_and_type(us, PAWN);
1097 assert(square_is_ok(s));
1098 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1100 if (square_file(s) == FILE_A)
1102 b2 = relative_square(us, SQ_B2);
1103 b3 = relative_square(us, SQ_B3);
1104 c3 = relative_square(us, SQ_C3);
1108 b2 = relative_square(us, SQ_G2);
1109 b3 = relative_square(us, SQ_G3);
1110 c3 = relative_square(us, SQ_F3);
1113 if (pos.piece_on(b2) == pawn)
1117 if (!pos.square_is_empty(b3))
1118 penalty = 2 * TrappedBishopA1H1Penalty;
1119 else if (pos.piece_on(c3) == pawn)
1120 penalty = TrappedBishopA1H1Penalty;
1122 penalty = TrappedBishopA1H1Penalty / 2;
1124 ei.value -= Sign[us] * penalty;
1129 // evaluate_space() computes the space evaluation for a given side. The
1130 // space evaluation is a simple bonus based on the number of safe squares
1131 // available for minor pieces on the central four files on ranks 2--4. Safe
1132 // squares one, two or three squares behind a friendly pawn are counted
1133 // twice. Finally, the space bonus is scaled by a weight taken from the
1134 // material hash table.
1135 template<Color Us, bool HasPopCnt>
1136 void evaluate_space(const Position& pos, EvalInfo& ei) {
1138 const Color Them = (Us == WHITE ? BLACK : WHITE);
1140 // Find the safe squares for our pieces inside the area defined by
1141 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1142 // pawn, or if it is undefended and attacked by an enemy piece.
1144 Bitboard safeSquares = SpaceMask[Us]
1145 & ~pos.pieces(PAWN, Us)
1146 & ~ei.attacked_by(Them, PAWN)
1147 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1149 // Find all squares which are at most three squares behind some friendly
1151 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1152 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1153 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1155 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1156 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1158 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1162 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1164 inline Score apply_weight(Score v, Score w) {
1165 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1169 // scale_by_game_phase() interpolates between a middle game and an endgame
1170 // score, based on game phase. It also scales the return value by a
1171 // ScaleFactor array.
1173 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1175 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1176 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1177 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1179 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1181 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1182 return Value(result & ~(GrainSize - 1));
1186 // weight_option() computes the value of an evaluation weight, by combining
1187 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1189 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1191 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1193 // Convert to integer to prevent overflow
1194 int mg = mg_value(uciWeight);
1195 int eg = eg_value(uciWeight);
1197 mg = (mg * 0x100) / 100;
1198 eg = (eg * 0x100) / 100;
1199 mg = (mg * mg_value(internalWeight)) / 0x100;
1200 eg = (eg * eg_value(internalWeight)) / 0x100;
1201 return make_score(mg, eg);
1204 // init_safety() initizes the king safety evaluation, based on UCI
1205 // parameters. It is called from read_weights().
1207 void init_safety() {
1215 // First setup the base table
1216 for (int i = 0; i < 100; i++)
1221 t[i] = Value((int)(a * (i - b) * (i - b)));
1224 for (int i = 1; i < 100; i++)
1226 if (t[i] - t[i - 1] > maxSlope)
1227 t[i] = t[i - 1] + Value(maxSlope);
1229 if (t[i] > Value(peak))
1233 // Then apply the weights and get the final SafetyTable[] array
1234 for (Color c = WHITE; c <= BLACK; c++)
1235 for (int i = 0; i < 100; i++)
1236 SafetyTable[c][i] = apply_weight(make_score(t[i], 0), WeightKingSafety[c]);