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);
283 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
284 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
285 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
286 inline Score apply_weight(Score v, Score weight);
287 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
288 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
297 /// evaluate() is the main evaluation function. It always computes two
298 /// values, an endgame score and a middle game score, and interpolates
299 /// between them based on the remaining material.
300 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
302 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
303 : do_evaluate<false>(pos, ei, threadID);
308 template<bool HasPopCnt>
309 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
312 ScaleFactor factor[2];
315 assert(threadID >= 0 && threadID < MAX_THREADS);
316 assert(!pos.is_check());
318 memset(&ei, 0, sizeof(EvalInfo));
320 // Initialize by reading the incrementally updated scores included in the
321 // position object (material + piece square tables)
322 ei.value = pos.value();
324 // Probe the material hash table
325 ei.mi = MaterialTable[threadID]->get_material_info(pos);
326 ei.value += ei.mi->material_value();
328 // If we have a specialized evaluation function for the current material
329 // configuration, call it and return
330 if (ei.mi->specialized_eval_exists())
331 return ei.mi->evaluate(pos);
333 // After get_material_info() call that modifies them
334 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
335 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
337 // Probe the pawn hash table
338 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
339 ei.value += apply_weight(ei.pi->pawns_value(), WeightPawnStructure);
341 // Initialize king attack bitboards and king attack zones for both sides
342 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
343 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
344 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
345 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
347 // Initialize pawn attack bitboards for both sides
348 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
349 b = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
351 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b)/2;
353 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
354 b = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
356 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b)/2;
359 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
360 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
362 // Kings. Kings are evaluated after all other pieces for both sides,
363 // because we need complete attack information for all pieces when computing
364 // the king safety evaluation.
365 evaluate_king<WHITE, HasPopCnt>(pos, ei);
366 evaluate_king<BLACK, HasPopCnt>(pos, ei);
368 // Evaluate tactical threats, we need full attack info including king
369 evaluate_threats<WHITE>(pos, ei);
370 evaluate_threats<BLACK>(pos, ei);
372 // Evaluate passed pawns, we need full attack info including king
373 evaluate_passed_pawns<WHITE>(pos, ei);
374 evaluate_passed_pawns<BLACK>(pos, ei);
376 // If one side has only a king, check whether exsists any unstoppable passed pawn
377 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
378 evaluate_unstoppable_pawns(pos, ei);
380 Phase phase = ei.mi->game_phase();
382 // Middle-game specific evaluation terms
383 if (phase > PHASE_ENDGAME)
385 // Pawn storms in positions with opposite castling
386 if ( square_file(pos.king_square(WHITE)) >= FILE_E
387 && square_file(pos.king_square(BLACK)) <= FILE_D)
389 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
391 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
392 && square_file(pos.king_square(BLACK)) >= FILE_E)
394 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
396 // Evaluate space for both sides
397 if (ei.mi->space_weight() > 0)
399 evaluate_space<WHITE, HasPopCnt>(pos, ei);
400 evaluate_space<BLACK, HasPopCnt>(pos, ei);
405 ei.value += apply_weight(ei.mobility, WeightMobility);
407 // If we don't already have an unusual scale factor, check for opposite
408 // colored bishop endgames, and use a lower scale for those
409 if ( phase < PHASE_MIDGAME
410 && pos.opposite_colored_bishops()
411 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
412 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
416 // Only the two bishops ?
417 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
418 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
420 // Check for KBP vs KB with only a single pawn that is almost
421 // certainly a draw or at least two pawns.
422 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
423 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
426 // Endgame with opposite-colored bishops, but also other pieces. Still
427 // a bit drawish, but not as drawish as with only the two bishops.
428 sf = ScaleFactor(50);
430 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
432 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
436 // Interpolate between the middle game and the endgame score
437 Color stm = pos.side_to_move();
439 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
441 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
446 /// init_eval() initializes various tables used by the evaluation function
448 void init_eval(int threads) {
450 assert(threads <= MAX_THREADS);
452 for (int i = 0; i < MAX_THREADS; i++)
457 delete MaterialTable[i];
459 MaterialTable[i] = NULL;
463 PawnTable[i] = new PawnInfoTable(PawnTableSize);
464 if (!MaterialTable[i])
465 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
470 /// quit_eval() releases heap-allocated memory at program termination
474 for (int i = 0; i < MAX_THREADS; i++)
477 delete MaterialTable[i];
479 MaterialTable[i] = NULL;
484 /// read_weights() reads evaluation weights from the corresponding UCI parameters
486 void read_weights(Color us) {
488 Color them = opposite_color(us);
490 WeightMobility = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightMobilityInternal);
491 WeightPawnStructure = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightPawnStructureInternal);
492 WeightPassedPawns = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightPassedPawnsInternal);
493 WeightSpace = weight_option("Space", "Space", WeightSpaceInternal);
494 WeightKingSafety[us] = weight_option("Cowardice", "Cowardice", WeightKingSafetyInternal);
495 WeightKingSafety[them] = weight_option("Aggressiveness", "Aggressiveness", WeightKingOppSafetyInternal);
497 // If running in analysis mode, make sure we use symmetrical king safety. We do this
498 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
499 if (get_option_value_bool("UCI_AnalyseMode"))
501 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
502 WeightKingSafety[them] = WeightKingSafety[us];
510 // evaluate_outposts() evaluates bishop and knight outposts squares
512 template<PieceType Piece, Color Us>
513 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
515 const Color Them = (Us == WHITE ? BLACK : WHITE);
517 // Initial bonus based on square
518 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
519 : KnightOutpostBonus[relative_square(Us, s)]);
521 // Increase bonus if supported by pawn, especially if the opponent has
522 // no minor piece which can exchange the outpost piece
523 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
525 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
526 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
527 bonus += bonus + bonus / 2;
531 ei.value += Sign[Us] * make_score(bonus, bonus);
535 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
537 template<PieceType Piece, Color Us, bool HasPopCnt>
538 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
545 const Color Them = (Us == WHITE ? BLACK : WHITE);
546 const Square* ptr = pos.piece_list_begin(Us, Piece);
548 while ((s = *ptr++) != SQ_NONE)
550 // Find attacked squares, including x-ray attacks for bishops and rooks
551 if (Piece == KNIGHT || Piece == QUEEN)
552 b = pos.attacks_from<Piece>(s);
553 else if (Piece == BISHOP)
554 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
555 else if (Piece == ROOK)
556 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
560 // Update attack info
561 ei.attackedBy[Us][Piece] |= b;
564 if (b & ei.kingZone[Us])
566 ei.kingAttackersCount[Us]++;
567 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
568 Bitboard bb = (b & ei.attackedBy[Them][KING]);
570 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
574 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
575 : count_1s<HasPopCnt>(b & no_mob_area));
577 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
579 // Decrease score if we are attacked by an enemy pawn. Remaining part
580 // of threat evaluation must be done later when we have full attack info.
581 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
582 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
584 // Bishop and knight outposts squares
585 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
586 evaluate_outposts<Piece, Us>(pos, ei, s);
588 // Special patterns: trapped bishops on a7/h7/a2/h2
589 // and trapped bishops on a1/h1/a8/h8 in Chess960.
592 if (bit_is_set(MaskA7H7[Us], s))
593 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
595 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
596 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
599 // Queen or rook on 7th rank
600 if ( (Piece == ROOK || Piece == QUEEN)
601 && relative_rank(Us, s) == RANK_7
602 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
604 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
607 // Special extra evaluation for rooks
610 // Open and half-open files
612 if (ei.pi->file_is_half_open(Us, f))
614 if (ei.pi->file_is_half_open(Them, f))
615 ei.value += Sign[Us] * RookOpenFileBonus;
617 ei.value += Sign[Us] * RookHalfOpenFileBonus;
620 // Penalize rooks which are trapped inside a king. Penalize more if
621 // king has lost right to castle.
622 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
625 ksq = pos.king_square(Us);
627 if ( square_file(ksq) >= FILE_E
628 && square_file(s) > square_file(ksq)
629 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
631 // Is there a half-open file between the king and the edge of the board?
632 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
633 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
634 : (TrappedRookPenalty - mob * 16), 0);
636 else if ( square_file(ksq) <= FILE_D
637 && square_file(s) < square_file(ksq)
638 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
640 // Is there a half-open file between the king and the edge of the board?
641 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
642 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
643 : (TrappedRookPenalty - mob * 16), 0);
650 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
651 // and the type of attacked one.
654 void evaluate_threats(const Position& pos, EvalInfo& ei) {
656 const Color Them = (Us == WHITE ? BLACK : WHITE);
659 Score bonus = make_score(0, 0);
661 // Enemy pieces not defended by a pawn and under our attack
662 Bitboard weakEnemies = pos.pieces_of_color(Them)
663 & ~ei.attackedBy[Them][PAWN]
664 & ei.attackedBy[Us][0];
668 // Add bonus according to type of attacked enemy pieces and to the
669 // type of attacking piece, from knights to queens. Kings are not
670 // considered because are already special handled in king evaluation.
671 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
673 b = ei.attackedBy[Us][pt1] & weakEnemies;
675 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
676 if (b & pos.pieces(pt2))
677 bonus += ThreatBonus[pt1][pt2];
679 ei.value += Sign[Us] * bonus;
683 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
684 // pieces of a given color.
686 template<Color Us, bool HasPopCnt>
687 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
689 const Color Them = (Us == WHITE ? BLACK : WHITE);
691 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
692 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
694 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
695 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
696 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
697 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
699 // Sum up all attacked squares
700 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
701 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
702 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
706 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
708 template<Color Us, bool HasPopCnt>
709 void evaluate_king(const Position& pos, EvalInfo& ei) {
711 const Color Them = (Us == WHITE ? BLACK : WHITE);
713 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
716 int attackUnits, count, shelter = 0;
717 const Square s = pos.king_square(Us);
720 if (relative_rank(Us, s) <= RANK_4)
722 shelter = ei.pi->get_king_shelter(pos, Us, s);
723 ei.value += Sign[Us] * make_score(shelter, 0);
726 // King safety. This is quite complicated, and is almost certainly far
727 // from optimally tuned.
728 if ( pos.piece_count(Them, QUEEN) >= 1
729 && ei.kingAttackersCount[Them] >= 2
730 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
731 && ei.kingAdjacentZoneAttacksCount[Them])
733 // Is it the attackers turn to move?
734 sente = (Them == pos.side_to_move());
736 // Find the attacked squares around the king which has no defenders
737 // apart from the king itself
738 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
739 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
740 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
741 | ei.attacked_by(Us, QUEEN));
743 // Initialize the 'attackUnits' variable, which is used later on as an
744 // index to the SafetyTable[] array. The initial value is based on the
745 // number and types of the attacking pieces, the number of attacked and
746 // undefended squares around the king, the square of the king, and the
747 // quality of the pawn shelter.
748 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
749 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
750 + InitKingDanger[relative_square(Us, s)]
753 // Analyse safe queen contact checks
754 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
757 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
758 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
760 b &= attackedByOthers;
762 // Squares attacked by the queen and supported by another enemy piece and
763 // not defended by other pieces but our king.
766 // The bitboard b now contains the squares available for safe queen
768 count = count_1s_max_15<HasPopCnt>(b);
769 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
771 // Is there a mate threat?
772 if (QueenContactMates && !pos.is_check())
774 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
775 occ = pos.occupied_squares();
778 to = pop_1st_bit(&b);
780 // Do we have escape squares from queen contact check attack ?
781 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
783 // We have a mate, unless the queen is pinned or there
784 // is an X-ray attack through the queen.
785 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
787 from = pos.piece_list(Them, QUEEN, i);
788 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
789 && !bit_is_set(pos.pinned_pieces(Them), from)
790 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
791 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
793 // Set the mate threat move
794 ei.mateThreat[Them] = make_move(from, to);
802 // Analyse safe distance checks
803 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
805 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
807 b = pos.attacks_from<ROOK>(s) & safe;
810 b2 = b & ei.attacked_by(Them, QUEEN);
812 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
815 b2 = b & ei.attacked_by(Them, ROOK);
817 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
819 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
821 b = pos.attacks_from<BISHOP>(s) & safe;
824 b2 = b & ei.attacked_by(Them, QUEEN);
826 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
829 b2 = b & ei.attacked_by(Them, BISHOP);
831 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
833 if (KnightCheckBonus > 0)
835 b = pos.attacks_from<KNIGHT>(s) & safe;
838 b2 = b & ei.attacked_by(Them, KNIGHT);
840 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
843 // Analyse discovered checks (only for non-pawns right now, consider
844 // adding pawns later).
845 if (DiscoveredCheckBonus)
847 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
849 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
852 // Has a mate threat been found? We don't do anything here if the
853 // side with the mating move is the side to move, because in that
854 // case the mating side will get a huge bonus at the end of the main
855 // evaluation function instead.
856 if (ei.mateThreat[Them] != MOVE_NONE)
857 attackUnits += MateThreatBonus;
859 // Ensure that attackUnits is between 0 and 99, in order to avoid array
860 // out of bounds errors.
861 attackUnits = Min(99, Max(0, attackUnits));
863 // Finally, extract the king safety score from the SafetyTable[] array.
864 // Add the score to the evaluation, and also to ei.futilityMargin. The
865 // reason for adding the king safety score to the futility margin is
866 // that the king safety scores can sometimes be very big, and that
867 // capturing a single attacking piece can therefore result in a score
868 // change far bigger than the value of the captured piece.
869 Score v = apply_weight(make_score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
870 ei.value -= Sign[Us] * v;
871 ei.futilityMargin[Us] += mg_value(v);
876 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
879 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
881 const Color Them = (Us == WHITE ? BLACK : WHITE);
883 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us);
887 Square s = pop_1st_bit(&b);
889 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
890 assert(pos.pawn_is_passed(Us, s));
892 int r = int(relative_rank(Us, s) - RANK_2);
893 int tr = Max(0, r * (r - 1));
895 // Base bonus based on rank
896 Value mbonus = Value(20 * tr);
897 Value ebonus = Value(10 + r * r * 10);
899 // Adjust bonus based on king proximity
902 Square blockSq = s + pawn_push(Us);
904 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * tr);
905 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * tr);
906 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
908 // If the pawn is free to advance, increase bonus
909 if (pos.square_is_empty(blockSq))
911 // There are no enemy pawns in the pawn's path
912 Bitboard b2 = squares_in_front_of(Us, s);
914 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
916 // Squares attacked by us
917 Bitboard b4 = b2 & ei.attacked_by(Us);
919 // Squares attacked or occupied by enemy pieces
920 Bitboard b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
922 // If there is an enemy rook or queen attacking the pawn from behind,
923 // add all X-ray attacks by the rook or queen.
924 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
925 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
928 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
929 if (b3 == EmptyBoardBB)
930 // No enemy attacks or pieces, huge bonus!
931 // Even bigger if we protect the pawn's path
932 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
934 // OK, there are enemy attacks or pieces (but not pawns). Are those
935 // squares which are attacked by the enemy also attacked by us ?
936 // If yes, big bonus (but smaller than when there are no enemy attacks),
937 // if no, somewhat smaller bonus.
938 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
940 // At last, add a small bonus when there are no *friendly* pieces
941 // in the pawn's path.
942 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
947 // If the pawn is supported by a friendly pawn, increase bonus
948 Bitboard b1 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
950 ebonus += Value(r * 20);
951 else if (pos.attacks_from<PAWN>(s, Them) & b1)
952 ebonus += Value(r * 12);
954 // Rook pawns are a special case: They are sometimes worse, and
955 // sometimes better than other passed pawns. It is difficult to find
956 // good rules for determining whether they are good or bad. For now,
957 // we try the following: Increase the value for rook pawns if the
958 // other side has no pieces apart from a knight, and decrease the
959 // value if the other side has a rook or queen.
960 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
962 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
963 && pos.piece_count(Them, KNIGHT) <= 1)
964 ebonus += ebonus / 4;
965 else if (pos.pieces(ROOK, QUEEN, Them))
966 ebonus -= ebonus / 4;
969 // Add the scores for this pawn to the middle game and endgame eval.
970 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
976 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides
978 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
980 int movesToGo[2] = {0, 0};
981 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
983 for (Color c = WHITE; c <= BLACK; c++)
985 // Skip evaluation if other side has non-pawn pieces
986 if (pos.non_pawn_material(opposite_color(c)))
989 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(c);
993 Square s = pop_1st_bit(&b);
994 Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8));
995 int d = square_distance(s, queeningSquare)
996 - square_distance(pos.king_square(opposite_color(c)), queeningSquare)
997 + int(c != pos.side_to_move());
1001 int mtg = RANK_8 - relative_rank(c, s);
1002 int blockerCount = count_1s_max_15(squares_in_front_of(c, s) & pos.occupied_squares());
1003 mtg += blockerCount;
1005 if (d < 0 && (!movesToGo[c] || movesToGo[c] > mtg))
1014 // Neither side has an unstoppable passed pawn?
1015 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1018 // Does only one side have an unstoppable passed pawn?
1019 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1021 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1022 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1025 { // Both sides have unstoppable pawns! Try to find out who queens
1026 // first. We begin by transforming 'movesToGo' to the number of
1027 // plies until the pawn queens for both sides.
1028 movesToGo[WHITE] *= 2;
1029 movesToGo[BLACK] *= 2;
1030 movesToGo[pos.side_to_move()]--;
1032 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1033 Color loserSide = opposite_color(winnerSide);
1035 // If one side queens at least three plies before the other, that side wins
1036 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1037 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1039 // If one side queens one ply before the other and checks the king or attacks
1040 // the undefended opponent's queening square, that side wins. To avoid cases
1041 // where the opponent's king could move somewhere before first pawn queens we
1042 // consider only free paths to queen for both pawns.
1043 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1044 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1046 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1048 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1049 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1051 Bitboard b = pos.occupied_squares();
1052 clear_bit(&b, pawnToGo[winnerSide]);
1053 clear_bit(&b, pawnToGo[loserSide]);
1054 b = queen_attacks_bb(winnerQSq, b);
1056 if ( (b & pos.pieces(KING, loserSide))
1057 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1058 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1064 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1065 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1068 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1070 assert(square_is_ok(s));
1071 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1073 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1074 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1076 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1077 && pos.see(s, b6) < 0
1078 && pos.see(s, b8) < 0)
1080 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1085 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1086 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1087 // black), and assigns a penalty if it is. This pattern can obviously
1088 // only occur in Chess960 games.
1090 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1092 Piece pawn = piece_of_color_and_type(us, PAWN);
1096 assert(square_is_ok(s));
1097 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1099 if (square_file(s) == FILE_A)
1101 b2 = relative_square(us, SQ_B2);
1102 b3 = relative_square(us, SQ_B3);
1103 c3 = relative_square(us, SQ_C3);
1107 b2 = relative_square(us, SQ_G2);
1108 b3 = relative_square(us, SQ_G3);
1109 c3 = relative_square(us, SQ_F3);
1112 if (pos.piece_on(b2) == pawn)
1116 if (!pos.square_is_empty(b3))
1117 penalty = 2 * TrappedBishopA1H1Penalty;
1118 else if (pos.piece_on(c3) == pawn)
1119 penalty = TrappedBishopA1H1Penalty;
1121 penalty = TrappedBishopA1H1Penalty / 2;
1123 ei.value -= Sign[us] * penalty;
1128 // evaluate_space() computes the space evaluation for a given side. The
1129 // space evaluation is a simple bonus based on the number of safe squares
1130 // available for minor pieces on the central four files on ranks 2--4. Safe
1131 // squares one, two or three squares behind a friendly pawn are counted
1132 // twice. Finally, the space bonus is scaled by a weight taken from the
1133 // material hash table.
1134 template<Color Us, bool HasPopCnt>
1135 void evaluate_space(const Position& pos, EvalInfo& ei) {
1137 const Color Them = (Us == WHITE ? BLACK : WHITE);
1139 // Find the safe squares for our pieces inside the area defined by
1140 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1141 // pawn, or if it is undefended and attacked by an enemy piece.
1143 Bitboard safeSquares = SpaceMask[Us]
1144 & ~pos.pieces(PAWN, Us)
1145 & ~ei.attacked_by(Them, PAWN)
1146 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1148 // Find all squares which are at most three squares behind some friendly
1150 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1151 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1152 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1154 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1155 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1157 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1161 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1163 inline Score apply_weight(Score v, Score w) {
1164 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1168 // scale_by_game_phase() interpolates between a middle game and an endgame
1169 // score, based on game phase. It also scales the return value by a
1170 // ScaleFactor array.
1172 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1174 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1175 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1176 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1178 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1180 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1181 return Value(result & ~(GrainSize - 1));
1185 // weight_option() computes the value of an evaluation weight, by combining
1186 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1188 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1190 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1192 // Convert to integer to prevent overflow
1193 int mg = mg_value(uciWeight);
1194 int eg = eg_value(uciWeight);
1196 mg = (mg * 0x100) / 100;
1197 eg = (eg * 0x100) / 100;
1198 mg = (mg * mg_value(internalWeight)) / 0x100;
1199 eg = (eg * eg_value(internalWeight)) / 0x100;
1200 return make_score(mg, eg);
1203 // init_safety() initizes the king safety evaluation, based on UCI
1204 // parameters. It is called from read_weights().
1206 void init_safety() {
1213 for (int i = 0; i < 100; i++)
1216 SafetyTable[i] = Value(0);
1218 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1221 for (int i = 1; i < 100; i++)
1223 if (SafetyTable[i] - SafetyTable[i - 1] > maxSlope)
1224 SafetyTable[i] = SafetyTable[i - 1] + Value(maxSlope);
1226 if (SafetyTable[i] > Value(peak))
1227 SafetyTable[i] = Value(peak);