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_passed_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 assert(threadID >= 0 && threadID < MAX_THREADS);
313 assert(!pos.is_check());
315 memset(&ei, 0, sizeof(EvalInfo));
317 // Initialize by reading the incrementally updated scores included in the
318 // position object (material + piece square tables)
319 ei.value = pos.value();
321 // Probe the material hash table
322 ei.mi = MaterialTable[threadID]->get_material_info(pos);
323 ei.value += ei.mi->material_value();
325 // If we have a specialized evaluation function for the current material
326 // configuration, call it and return
327 if (ei.mi->specialized_eval_exists())
328 return ei.mi->evaluate(pos);
330 // After get_material_info() call that modifies them
331 ScaleFactor factor[2];
332 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
333 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
335 // Probe the pawn hash table
336 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
337 ei.value += apply_weight(ei.pi->pawns_value(), WeightPawnStructure);
339 // Initialize king attack bitboards and king attack zones for both sides
340 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
341 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
342 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
343 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
345 // Initialize pawn attack bitboards for both sides
346 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
347 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
348 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
349 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
351 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
354 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
357 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
358 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
360 // Kings. Kings are evaluated after all other pieces for both sides,
361 // because we need complete attack information for all pieces when computing
362 // the king safety evaluation.
363 evaluate_king<WHITE, HasPopCnt>(pos, ei);
364 evaluate_king<BLACK, HasPopCnt>(pos, ei);
366 // Evaluate tactical threats, we need full attack info
367 evaluate_threats<WHITE>(pos, ei);
368 evaluate_threats<BLACK>(pos, ei);
370 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
371 // because we need to know which side promotes first in positions where
372 // both sides have an unstoppable passed pawn. To be called after all attacks
373 // are computed, included king.
374 if (ei.pi->passed_pawns())
375 evaluate_passed_pawns(pos, ei);
377 Phase phase = ei.mi->game_phase();
379 // Middle-game specific evaluation terms
380 if (phase > PHASE_ENDGAME)
382 // Pawn storms in positions with opposite castling.
383 if ( square_file(pos.king_square(WHITE)) >= FILE_E
384 && square_file(pos.king_square(BLACK)) <= FILE_D)
386 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
388 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
389 && square_file(pos.king_square(BLACK)) >= FILE_E)
391 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
393 // Evaluate space for both sides
394 if (ei.mi->space_weight() > 0)
396 evaluate_space<WHITE, HasPopCnt>(pos, ei);
397 evaluate_space<BLACK, HasPopCnt>(pos, ei);
402 ei.value += apply_weight(ei.mobility, WeightMobility);
404 // If we don't already have an unusual scale factor, check for opposite
405 // colored bishop endgames, and use a lower scale for those
406 if ( phase < PHASE_MIDGAME
407 && pos.opposite_colored_bishops()
408 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
409 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
413 // Only the two bishops ?
414 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
415 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
417 // Check for KBP vs KB with only a single pawn that is almost
418 // certainly a draw or at least two pawns.
419 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
420 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
423 // Endgame with opposite-colored bishops, but also other pieces. Still
424 // a bit drawish, but not as drawish as with only the two bishops.
425 sf = ScaleFactor(50);
427 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
429 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
433 // Interpolate between the middle game and the endgame score
434 Color stm = pos.side_to_move();
436 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
438 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
443 /// init_eval() initializes various tables used by the evaluation function
445 void init_eval(int threads) {
447 assert(threads <= MAX_THREADS);
449 for (int i = 0; i < MAX_THREADS; i++)
454 delete MaterialTable[i];
456 MaterialTable[i] = NULL;
460 PawnTable[i] = new PawnInfoTable(PawnTableSize);
461 if (!MaterialTable[i])
462 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
467 /// quit_eval() releases heap-allocated memory at program termination
471 for (int i = 0; i < MAX_THREADS; i++)
474 delete MaterialTable[i];
476 MaterialTable[i] = NULL;
481 /// read_weights() reads evaluation weights from the corresponding UCI parameters
483 void read_weights(Color us) {
485 Color them = opposite_color(us);
487 WeightMobility = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightMobilityInternal);
488 WeightPawnStructure = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightPawnStructureInternal);
489 WeightPassedPawns = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightPassedPawnsInternal);
490 WeightSpace = weight_option("Space", "Space", WeightSpaceInternal);
491 WeightKingSafety[us] = weight_option("Cowardice", "Cowardice", WeightKingSafetyInternal);
492 WeightKingSafety[them] = weight_option("Aggressiveness", "Aggressiveness", WeightKingOppSafetyInternal);
494 // If running in analysis mode, make sure we use symmetrical king safety. We do this
495 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
496 if (get_option_value_bool("UCI_AnalyseMode"))
498 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
499 WeightKingSafety[them] = WeightKingSafety[us];
507 // evaluate_outposts() evaluates bishop and knight outposts squares
509 template<PieceType Piece, Color Us>
510 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
512 const Color Them = (Us == WHITE ? BLACK : WHITE);
514 // Initial bonus based on square
515 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
516 : KnightOutpostBonus[relative_square(Us, s)]);
518 // Increase bonus if supported by pawn, especially if the opponent has
519 // no minor piece which can exchange the outpost piece
520 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
522 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
523 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
524 bonus += bonus + bonus / 2;
528 ei.value += Sign[Us] * make_score(bonus, bonus);
532 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
534 template<PieceType Piece, Color Us, bool HasPopCnt>
535 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
542 const Color Them = (Us == WHITE ? BLACK : WHITE);
543 const Square* ptr = pos.piece_list_begin(Us, Piece);
545 while ((s = *ptr++) != SQ_NONE)
547 // Find attacked squares, including x-ray attacks for bishops and rooks
548 if (Piece == KNIGHT || Piece == QUEEN)
549 b = pos.attacks_from<Piece>(s);
550 else if (Piece == BISHOP)
551 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
552 else if (Piece == ROOK)
553 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
557 // Update attack info
558 ei.attackedBy[Us][Piece] |= b;
561 if (b & ei.kingZone[Us])
563 ei.kingAttackersCount[Us]++;
564 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
565 Bitboard bb = (b & ei.attackedBy[Them][KING]);
567 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
571 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
572 : count_1s<HasPopCnt>(b & no_mob_area));
574 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
576 // Decrease score if we are attacked by an enemy pawn. Remaining part
577 // of threat evaluation must be done later when we have full attack info.
578 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
579 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
581 // Bishop and knight outposts squares
582 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
583 evaluate_outposts<Piece, Us>(pos, ei, s);
585 // Special patterns: trapped bishops on a7/h7/a2/h2
586 // and trapped bishops on a1/h1/a8/h8 in Chess960.
589 if (bit_is_set(MaskA7H7[Us], s))
590 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
592 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
593 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
596 // Queen or rook on 7th rank
597 if ( (Piece == ROOK || Piece == QUEEN)
598 && relative_rank(Us, s) == RANK_7
599 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
601 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
604 // Special extra evaluation for rooks
607 // Open and half-open files
609 if (ei.pi->file_is_half_open(Us, f))
611 if (ei.pi->file_is_half_open(Them, f))
612 ei.value += Sign[Us] * RookOpenFileBonus;
614 ei.value += Sign[Us] * RookHalfOpenFileBonus;
617 // Penalize rooks which are trapped inside a king. Penalize more if
618 // king has lost right to castle.
619 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
622 ksq = pos.king_square(Us);
624 if ( square_file(ksq) >= FILE_E
625 && square_file(s) > square_file(ksq)
626 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
628 // Is there a half-open file between the king and the edge of the board?
629 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
630 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
631 : (TrappedRookPenalty - mob * 16), 0);
633 else if ( square_file(ksq) <= FILE_D
634 && square_file(s) < square_file(ksq)
635 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
637 // Is there a half-open file between the king and the edge of the board?
638 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
639 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
640 : (TrappedRookPenalty - mob * 16), 0);
647 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
648 // and the type of attacked one.
651 void evaluate_threats(const Position& pos, EvalInfo& ei) {
653 const Color Them = (Us == WHITE ? BLACK : WHITE);
656 Score bonus = make_score(0, 0);
658 // Enemy pieces not defended by a pawn and under our attack
659 Bitboard weakEnemies = pos.pieces_of_color(Them)
660 & ~ei.attackedBy[Them][PAWN]
661 & ei.attackedBy[Us][0];
665 // Add bonus according to type of attacked enemy pieces and to the
666 // type of attacking piece, from knights to queens. Kings are not
667 // considered because are already special handled in king evaluation.
668 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
670 b = ei.attackedBy[Us][pt1] & weakEnemies;
672 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
673 if (b & pos.pieces(pt2))
674 bonus += ThreatBonus[pt1][pt2];
676 ei.value += Sign[Us] * bonus;
680 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
681 // pieces of a given color.
683 template<Color Us, bool HasPopCnt>
684 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
686 const Color Them = (Us == WHITE ? BLACK : WHITE);
688 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
689 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
691 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
692 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
693 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
694 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
696 // Sum up all attacked squares
697 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
698 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
699 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
703 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
705 template<Color Us, bool HasPopCnt>
706 void evaluate_king(const Position& pos, EvalInfo& ei) {
708 const Color Them = (Us == WHITE ? BLACK : WHITE);
710 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
713 int attackUnits, count, shelter = 0;
714 const Square s = pos.king_square(Us);
717 if (relative_rank(Us, s) <= RANK_4)
719 shelter = ei.pi->get_king_shelter(pos, Us, s);
720 ei.value += Sign[Us] * make_score(shelter, 0);
723 // King safety. This is quite complicated, and is almost certainly far
724 // from optimally tuned.
725 if ( pos.piece_count(Them, QUEEN) >= 1
726 && ei.kingAttackersCount[Them] >= 2
727 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
728 && ei.kingAdjacentZoneAttacksCount[Them])
730 // Is it the attackers turn to move?
731 sente = (Them == pos.side_to_move());
733 // Find the attacked squares around the king which has no defenders
734 // apart from the king itself
735 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
736 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
737 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
738 | ei.attacked_by(Us, QUEEN));
740 // Initialize the 'attackUnits' variable, which is used later on as an
741 // index to the SafetyTable[] array. The initial value is based on the
742 // number and types of the attacking pieces, the number of attacked and
743 // undefended squares around the king, the square of the king, and the
744 // quality of the pawn shelter.
745 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
746 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
747 + InitKingDanger[relative_square(Us, s)]
750 // Analyse safe queen contact checks
751 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
754 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
755 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
757 b &= attackedByOthers;
759 // Squares attacked by the queen and supported by another enemy piece and
760 // not defended by other pieces but our king.
763 // The bitboard b now contains the squares available for safe queen
765 count = count_1s_max_15<HasPopCnt>(b);
766 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
768 // Is there a mate threat?
769 if (QueenContactMates && !pos.is_check())
771 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
772 occ = pos.occupied_squares();
775 to = pop_1st_bit(&b);
777 // Do we have escape squares from queen contact check attack ?
778 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
780 // We have a mate, unless the queen is pinned or there
781 // is an X-ray attack through the queen.
782 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
784 from = pos.piece_list(Them, QUEEN, i);
785 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
786 && !bit_is_set(pos.pinned_pieces(Them), from)
787 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
788 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
790 // Set the mate threat move
791 ei.mateThreat[Them] = make_move(from, to);
799 // Analyse safe distance checks
800 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
802 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
804 b = pos.attacks_from<ROOK>(s) & safe;
807 b2 = b & ei.attacked_by(Them, QUEEN);
809 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
812 b2 = b & ei.attacked_by(Them, ROOK);
814 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
816 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
818 b = pos.attacks_from<BISHOP>(s) & safe;
821 b2 = b & ei.attacked_by(Them, QUEEN);
823 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
826 b2 = b & ei.attacked_by(Them, BISHOP);
828 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
830 if (KnightCheckBonus > 0)
832 b = pos.attacks_from<KNIGHT>(s) & safe;
835 b2 = b & ei.attacked_by(Them, KNIGHT);
837 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
840 // Analyse discovered checks (only for non-pawns right now, consider
841 // adding pawns later).
842 if (DiscoveredCheckBonus)
844 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
846 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
849 // Has a mate threat been found? We don't do anything here if the
850 // side with the mating move is the side to move, because in that
851 // case the mating side will get a huge bonus at the end of the main
852 // evaluation function instead.
853 if (ei.mateThreat[Them] != MOVE_NONE)
854 attackUnits += MateThreatBonus;
856 // Ensure that attackUnits is between 0 and 99, in order to avoid array
857 // out of bounds errors.
858 attackUnits = Min(99, Max(0, attackUnits));
860 // Finally, extract the king safety score from the SafetyTable[] array.
861 // Add the score to the evaluation, and also to ei.futilityMargin. The
862 // reason for adding the king safety score to the futility margin is
863 // that the king safety scores can sometimes be very big, and that
864 // capturing a single attacking piece can therefore result in a score
865 // change far bigger than the value of the captured piece.
866 Score v = apply_weight(make_score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
867 ei.value -= Sign[Us] * v;
868 ei.futilityMargin[Us] += mg_value(v);
873 // evaluate_passed_pawns_of_color() evaluates the passed pawns of the given color
876 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
878 const Color Them = (Us == WHITE ? BLACK : WHITE);
881 Square ourKingSq = pos.king_square(Us);
882 Square theirKingSq = pos.king_square(Them);
883 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, 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(ourKingSq, blockSq) * 3 * tr);
905 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
906 ebonus += Value(square_distance(theirKingSq, 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 b2 = squares_in_front_of(Us, s);
914 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
916 // Squares attacked by us
917 b4 = b2 & ei.attacked_by(Us);
919 // Squares attacked or occupied by enemy pieces
920 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 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
950 ebonus += Value(r * 20);
951 else if (pos.attacks_from<PAWN>(s, Them) & b2)
952 ebonus += Value(r * 12);
954 // If the other side has only a king, check whether the pawn is
956 if (pos.non_pawn_material(Them) == Value(0))
961 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
962 d = square_distance(s, qsq)
963 - square_distance(theirKingSq, qsq)
964 + (Us != pos.side_to_move());
968 int mtg = RANK_8 - relative_rank(Us, s);
969 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
972 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
980 // Rook pawns are a special case: They are sometimes worse, and
981 // sometimes better than other passed pawns. It is difficult to find
982 // good rules for determining whether they are good or bad. For now,
983 // we try the following: Increase the value for rook pawns if the
984 // other side has no pieces apart from a knight, and decrease the
985 // value if the other side has a rook or queen.
986 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
988 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
989 && pos.piece_count(Them, KNIGHT) <= 1)
990 ebonus += ebonus / 4;
991 else if (pos.pieces(ROOK, QUEEN, Them))
992 ebonus -= ebonus / 4;
995 // Add the scores for this pawn to the middle game and endgame eval.
996 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
1002 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1004 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1006 int movesToGo[2] = {0, 0};
1007 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1009 // Evaluate pawns for each color
1010 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1011 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1013 // Neither side has an unstoppable passed pawn?
1014 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1017 // Does only one side have an unstoppable passed pawn?
1018 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1020 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1021 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1024 { // Both sides have unstoppable pawns! Try to find out who queens
1025 // first. We begin by transforming 'movesToGo' to the number of
1026 // plies until the pawn queens for both sides.
1027 movesToGo[WHITE] *= 2;
1028 movesToGo[BLACK] *= 2;
1029 movesToGo[pos.side_to_move()]--;
1031 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1032 Color loserSide = opposite_color(winnerSide);
1034 // If one side queens at least three plies before the other, that side wins
1035 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1036 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1038 // If one side queens one ply before the other and checks the king or attacks
1039 // the undefended opponent's queening square, that side wins. To avoid cases
1040 // where the opponent's king could move somewhere before first pawn queens we
1041 // consider only free paths to queen for both pawns.
1042 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1043 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1045 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1047 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1048 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1050 Bitboard b = pos.occupied_squares();
1051 clear_bit(&b, pawnToGo[winnerSide]);
1052 clear_bit(&b, pawnToGo[loserSide]);
1053 b = queen_attacks_bb(winnerQSq, b);
1055 if ( (b & pos.pieces(KING, loserSide))
1056 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1057 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1063 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1064 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1067 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1069 assert(square_is_ok(s));
1070 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1072 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1073 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1075 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1076 && pos.see(s, b6) < 0
1077 && pos.see(s, b8) < 0)
1079 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1084 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1085 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1086 // black), and assigns a penalty if it is. This pattern can obviously
1087 // only occur in Chess960 games.
1089 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1091 Piece pawn = piece_of_color_and_type(us, PAWN);
1095 assert(square_is_ok(s));
1096 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1098 if (square_file(s) == FILE_A)
1100 b2 = relative_square(us, SQ_B2);
1101 b3 = relative_square(us, SQ_B3);
1102 c3 = relative_square(us, SQ_C3);
1106 b2 = relative_square(us, SQ_G2);
1107 b3 = relative_square(us, SQ_G3);
1108 c3 = relative_square(us, SQ_F3);
1111 if (pos.piece_on(b2) == pawn)
1115 if (!pos.square_is_empty(b3))
1116 penalty = 2 * TrappedBishopA1H1Penalty;
1117 else if (pos.piece_on(c3) == pawn)
1118 penalty = TrappedBishopA1H1Penalty;
1120 penalty = TrappedBishopA1H1Penalty / 2;
1122 ei.value -= Sign[us] * penalty;
1127 // evaluate_space() computes the space evaluation for a given side. The
1128 // space evaluation is a simple bonus based on the number of safe squares
1129 // available for minor pieces on the central four files on ranks 2--4. Safe
1130 // squares one, two or three squares behind a friendly pawn are counted
1131 // twice. Finally, the space bonus is scaled by a weight taken from the
1132 // material hash table.
1133 template<Color Us, bool HasPopCnt>
1134 void evaluate_space(const Position& pos, EvalInfo& ei) {
1136 const Color Them = (Us == WHITE ? BLACK : WHITE);
1138 // Find the safe squares for our pieces inside the area defined by
1139 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1140 // pawn, or if it is undefended and attacked by an enemy piece.
1142 Bitboard safeSquares = SpaceMask[Us]
1143 & ~pos.pieces(PAWN, Us)
1144 & ~ei.attacked_by(Them, PAWN)
1145 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1147 // Find all squares which are at most three squares behind some friendly
1149 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1150 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1151 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1153 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1154 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1156 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1160 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1162 inline Score apply_weight(Score v, Score w) {
1163 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1167 // scale_by_game_phase() interpolates between a middle game and an endgame
1168 // score, based on game phase. It also scales the return value by a
1169 // ScaleFactor array.
1171 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1173 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1174 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1175 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1177 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1179 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1180 return Value(result & ~(GrainSize - 1));
1184 // weight_option() computes the value of an evaluation weight, by combining
1185 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1187 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1189 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1191 // Convert to integer to prevent overflow
1192 int mg = mg_value(uciWeight);
1193 int eg = eg_value(uciWeight);
1195 mg = (mg * 0x100) / 100;
1196 eg = (eg * 0x100) / 100;
1197 mg = (mg * mg_value(internalWeight)) / 0x100;
1198 eg = (eg * eg_value(internalWeight)) / 0x100;
1199 return make_score(mg, eg);
1202 // init_safety() initizes the king safety evaluation, based on UCI
1203 // parameters. It is called from read_weights().
1205 void init_safety() {
1212 for (int i = 0; i < 100; i++)
1215 SafetyTable[i] = Value(0);
1217 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1220 for (int i = 0; i < 100; i++)
1222 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1223 for (int j = i + 1; j < 100; j++)
1224 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1226 if (SafetyTable[i] > Value(peak))
1227 SafetyTable[i] = Value(peak);