2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2009 Marco Costalba
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
34 #include "ucioption.h"
38 //// Local definitions
43 const int Sign[2] = { 1, -1 };
45 // Evaluation grain size, must be a power of 2
46 const int GrainSize = 8;
48 // Evaluation weights, initialized from UCI options
49 Score WeightMobility, WeightPawnStructure;
50 Score WeightPassedPawns, WeightSpace;
51 Score WeightKingSafety[2];
53 // Internal evaluation weights. These are applied on top of the evaluation
54 // weights read from UCI parameters. The purpose is to be able to change
55 // the evaluation weights while keeping the default values of the UCI
56 // parameters at 100, which looks prettier.
58 // Values modified by Joona Kiiski
59 const Score WeightMobilityInternal = make_score(248, 271);
60 const Score WeightPawnStructureInternal = make_score(233, 201);
61 const Score WeightPassedPawnsInternal = make_score(252, 259);
62 const Score WeightSpaceInternal = make_score( 46, 0);
63 const Score WeightKingSafetyInternal = make_score(247, 0);
64 const Score WeightKingOppSafetyInternal = make_score(259, 0);
66 // Mobility and outposts bonus modified by Joona Kiiski
68 // Visually better to define tables constants
70 #define S(mg, eg) make_score(mg, eg)
74 // Knight mobility bonus in middle game and endgame, indexed by the number
75 // of attacked squares not occupied by friendly piecess.
76 const Score KnightMobilityBonus[16] = {
77 S(-38,-33), S(-25,-23), S(-12,-13), S( 0,-3),
78 S( 12, 7), S( 25, 17), S( 31, 22), S(38, 27), S(38, 27)
81 // Bishop mobility bonus in middle game and endgame, indexed by the number
82 // of attacked squares not occupied by friendly pieces. X-ray attacks through
83 // queens are also included.
84 const Score BishopMobilityBonus[16] = {
85 S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12),
86 S( 31, 26), S( 45, 40), S(57, 52), S(65, 60),
87 S( 71, 65), S( 74, 69), S(76, 71), S(78, 73),
88 S( 79, 74), S( 80, 75), S(81, 76), S(81, 76)
91 // Rook mobility bonus in middle game and endgame, indexed by the number
92 // of attacked squares not occupied by friendly pieces. X-ray attacks through
93 // queens and rooks are also included.
94 const Score RookMobilityBonus[16] = {
95 S(-20,-36), S(-14,-19), S(-8, -3), S(-2, 13),
96 S( 4, 29), S( 10, 46), S(14, 62), S(19, 79),
97 S( 23, 95), S( 26,106), S(27,111), S(28,114),
98 S( 29,116), S( 30,117), S(31,118), S(32,118)
101 // Queen mobility bonus in middle game and endgame, indexed by the number
102 // of attacked squares not occupied by friendly pieces.
103 const Score QueenMobilityBonus[32] = {
104 S(-10,-18), S(-8,-13), S(-6, -7), S(-3, -2), S(-1, 3), S( 1, 8),
105 S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
106 S( 16, 35), S(17, 35), S(18, 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), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
109 S( 20, 35), S(20, 35)
112 // Pointers table to access mobility tables through piece type
113 const Score* MobilityBonus[8] = { 0, 0, KnightMobilityBonus, BishopMobilityBonus,
114 RookMobilityBonus, QueenMobilityBonus, 0, 0 };
116 // Outpost bonuses for knights and bishops, indexed by square (from white's
118 const Value KnightOutpostBonus[64] = {
120 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
121 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
122 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
123 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
124 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
125 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
126 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
127 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
130 const Value BishopOutpostBonus[64] = {
132 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
133 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
134 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
135 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
136 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
137 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
138 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
139 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
142 // ThreatBonus[][] contains bonus according to which piece type
143 // attacks which one.
144 #define Z make_score(0, 0)
146 const Score ThreatBonus[8][8] = {
147 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
148 { Z, S(18,37), Z, S(37,47), S(55,97), S(55,97), Z, Z }, // KNIGHT attacks
149 { Z, S(18,37), S(37,47), Z, S(55,97), S(55,97), Z, Z }, // BISHOP attacks
150 { Z, S( 9,27), S(27,47), S(27,47), Z, S(37,47), Z, Z }, // ROOK attacks
151 { Z, S(27,37), S(27,37), S(27,37), S(27,37), Z, Z, Z }, // QUEEN attacks
152 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
153 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
154 { Z, Z, Z, Z, Z, Z, Z, Z } // not used
157 // ThreatedByPawnPenalty[] contains a penalty according to which piece
158 // type is attacked by an enemy pawn.
159 const Score ThreatedByPawnPenalty[8] = {
160 Z, Z, S(56, 70), S(56, 70), S(76, 99), S(86, 118), Z, Z
166 // Bonus for unstoppable passed pawns
167 const Value UnstoppablePawnValue = Value(0x500);
169 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
170 const Score RookOn7thBonus = make_score(47, 98);
171 const Score QueenOn7thBonus = make_score(27, 54);
173 // Rooks on open files (modified by Joona Kiiski)
174 const Score RookOpenFileBonus = make_score(43, 43);
175 const Score RookHalfOpenFileBonus = make_score(19, 19);
177 // Penalty for rooks trapped inside a friendly king which has lost the
179 const Value TrappedRookPenalty = Value(180);
181 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
183 const Score TrappedBishopA7H7Penalty = make_score(300, 300);
185 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
186 const Bitboard MaskA7H7[2] = {
187 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
188 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
191 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
192 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
193 // happen in Chess960 games.
194 const Score TrappedBishopA1H1Penalty = make_score(100, 100);
196 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
197 const Bitboard MaskA1H1[2] = {
198 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
199 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
202 // The SpaceMask[color] contains the area of the board which is considered
203 // by the space evaluation. In the middle game, each side is given a bonus
204 // based on how many squares inside this area are safe and available for
205 // friendly minor pieces.
206 const Bitboard SpaceMask[2] = {
207 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
208 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
209 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
210 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
211 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
212 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
215 /// King safety constants and variables. The king safety scores are taken
216 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
217 /// the strength of the attack are added up into an integer, which is used
218 /// as an index to SafetyTable[].
220 // Attack weights for each piece type and table indexed on piece type
221 const int QueenAttackWeight = 5;
222 const int RookAttackWeight = 3;
223 const int BishopAttackWeight = 2;
224 const int KnightAttackWeight = 2;
226 const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
228 // Bonuses for safe checks, initialized from UCI options
229 int QueenContactCheckBonus, DiscoveredCheckBonus;
230 int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
232 // Scan for queen contact mates?
233 const bool QueenContactMates = true;
235 // Bonus for having a mate threat, initialized from UCI options
238 // InitKingDanger[] contains bonuses based on the position of the defending
240 const int InitKingDanger[64] = {
241 2, 0, 2, 5, 5, 2, 0, 2,
242 2, 2, 4, 8, 8, 4, 2, 2,
243 7, 10, 12, 12, 12, 12, 10, 7,
244 15, 15, 15, 15, 15, 15, 15, 15,
245 15, 15, 15, 15, 15, 15, 15, 15,
246 15, 15, 15, 15, 15, 15, 15, 15,
247 15, 15, 15, 15, 15, 15, 15, 15,
248 15, 15, 15, 15, 15, 15, 15, 15
251 // SafetyTable[] contains the actual king safety scores. It is initialized
253 Value SafetyTable[100];
255 // Pawn and material hash tables, indexed by the current thread id
256 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
257 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
259 // Sizes of pawn and material hash tables
260 const int PawnTableSize = 16384;
261 const int MaterialTableSize = 1024;
263 // Function prototypes
264 template<bool HasPopCnt>
265 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
267 template<Color Us, bool HasPopCnt>
268 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
270 template<Color Us, bool HasPopCnt>
271 void evaluate_king(const Position& pos, EvalInfo& ei);
274 void evaluate_threats(const Position& pos, EvalInfo& ei);
276 template<Color Us, bool HasPopCnt>
277 void evaluate_space(const Position& pos, EvalInfo& ei);
279 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
280 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
281 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
282 inline Score apply_weight(Score v, Score weight);
283 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
284 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
293 /// evaluate() is the main evaluation function. It always computes two
294 /// values, an endgame score and a middle game score, and interpolates
295 /// between them based on the remaining material.
296 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
298 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
299 : do_evaluate<false>(pos, ei, threadID);
304 template<bool HasPopCnt>
305 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
308 assert(threadID >= 0 && threadID < THREAD_MAX);
309 assert(!pos.is_check());
311 memset(&ei, 0, sizeof(EvalInfo));
313 // Initialize by reading the incrementally updated scores included in the
314 // position object (material + piece square tables)
315 ei.value = pos.value();
317 // Probe the material hash table
318 ei.mi = MaterialTable[threadID]->get_material_info(pos);
319 ei.value += ei.mi->material_value();
321 // If we have a specialized evaluation function for the current material
322 // configuration, call it and return
323 if (ei.mi->specialized_eval_exists())
324 return ei.mi->evaluate(pos);
326 // After get_material_info() call that modifies them
327 ScaleFactor factor[2];
328 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
329 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
331 // Probe the pawn hash table
332 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
333 ei.value += apply_weight(ei.pi->value(), WeightPawnStructure);
335 // Initialize king attack bitboards and king attack zones for both sides
336 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
337 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
338 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
339 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
341 // Initialize pawn attack bitboards for both sides
342 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
343 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
344 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
345 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
347 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
350 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
353 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
354 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
356 // Kings. Kings are evaluated after all other pieces for both sides,
357 // because we need complete attack information for all pieces when computing
358 // the king safety evaluation.
359 evaluate_king<WHITE, HasPopCnt>(pos, ei);
360 evaluate_king<BLACK, HasPopCnt>(pos, ei);
362 // Evaluate tactical threats, we need full attack info
363 evaluate_threats<WHITE>(pos, ei);
364 evaluate_threats<BLACK>(pos, ei);
366 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
367 // because we need to know which side promotes first in positions where
368 // both sides have an unstoppable passed pawn. To be called after all attacks
369 // are computed, included king.
370 if (ei.pi->passed_pawns())
371 evaluate_passed_pawns(pos, ei);
373 Phase phase = pos.game_phase();
375 // Middle-game specific evaluation terms
376 if (phase > PHASE_ENDGAME)
378 // Pawn storms in positions with opposite castling.
379 if ( square_file(pos.king_square(WHITE)) >= FILE_E
380 && square_file(pos.king_square(BLACK)) <= FILE_D)
382 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
384 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
385 && square_file(pos.king_square(BLACK)) >= FILE_E)
387 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
389 // Evaluate space for both sides
390 if (ei.mi->space_weight() > 0)
392 evaluate_space<WHITE, HasPopCnt>(pos, ei);
393 evaluate_space<BLACK, HasPopCnt>(pos, ei);
398 ei.value += apply_weight(ei.mobility, WeightMobility);
400 // If we don't already have an unusual scale factor, check for opposite
401 // colored bishop endgames, and use a lower scale for those
402 if ( phase < PHASE_MIDGAME
403 && pos.opposite_colored_bishops()
404 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
405 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
409 // Only the two bishops ?
410 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
411 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
413 // Check for KBP vs KB with only a single pawn that is almost
414 // certainly a draw or at least two pawns.
415 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
416 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
419 // Endgame with opposite-colored bishops, but also other pieces. Still
420 // a bit drawish, but not as drawish as with only the two bishops.
421 sf = ScaleFactor(50);
423 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
425 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
429 // Interpolate between the middle game and the endgame score
430 Color stm = pos.side_to_move();
432 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
434 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
439 /// quick_evaluate() does a very approximate evaluation of the current position.
440 /// It currently considers only material and piece square table scores. Perhaps
441 /// we should add scores from the pawn and material hash tables?
443 Value quick_evaluate(const Position &pos) {
448 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
450 Phase ph = pos.game_phase();
451 Color stm = pos.side_to_move();
453 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
457 /// init_eval() initializes various tables used by the evaluation function
459 void init_eval(int threads) {
461 assert(threads <= THREAD_MAX);
463 for (int i = 0; i < THREAD_MAX; i++)
468 delete MaterialTable[i];
470 MaterialTable[i] = NULL;
474 PawnTable[i] = new PawnInfoTable(PawnTableSize);
475 if (!MaterialTable[i])
476 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
481 /// quit_eval() releases heap-allocated memory at program termination
485 for (int i = 0; i < THREAD_MAX; i++)
488 delete MaterialTable[i];
490 MaterialTable[i] = NULL;
495 /// read_weights() reads evaluation weights from the corresponding UCI parameters
497 void read_weights(Color us) {
499 Color them = opposite_color(us);
501 WeightMobility = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightMobilityInternal);
502 WeightPawnStructure = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightPawnStructureInternal);
503 WeightPassedPawns = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightPassedPawnsInternal);
504 WeightSpace = weight_option("Space", "Space", WeightSpaceInternal);
505 WeightKingSafety[us] = weight_option("Cowardice", "Cowardice", WeightKingSafetyInternal);
506 WeightKingSafety[them] = weight_option("Aggressiveness", "Aggressiveness", WeightKingOppSafetyInternal);
508 // If running in analysis mode, make sure we use symmetrical king safety. We do this
509 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
510 if (get_option_value_bool("UCI_AnalyseMode"))
512 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
513 WeightKingSafety[them] = WeightKingSafety[us];
521 // evaluate_outposts() evaluates bishop and knight outposts squares
523 template<PieceType Piece, Color Us>
524 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
526 const Color Them = (Us == WHITE ? BLACK : WHITE);
528 // Initial bonus based on square
529 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
530 : KnightOutpostBonus[relative_square(Us, s)]);
532 // Increase bonus if supported by pawn, especially if the opponent has
533 // no minor piece which can exchange the outpost piece
534 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
536 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
537 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
538 bonus += bonus + bonus / 2;
542 ei.value += Sign[Us] * make_score(bonus, bonus);
546 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
548 template<PieceType Piece, Color Us, bool HasPopCnt>
549 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
556 const Color Them = (Us == WHITE ? BLACK : WHITE);
557 const Square* ptr = pos.piece_list_begin(Us, Piece);
559 while ((s = *ptr++) != SQ_NONE)
561 // Find attacked squares, including x-ray attacks for bishops and rooks
562 if (Piece == KNIGHT || Piece == QUEEN)
563 b = pos.attacks_from<Piece>(s);
564 else if (Piece == BISHOP)
565 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
566 else if (Piece == ROOK)
567 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
571 // Update attack info
572 ei.attackedBy[Us][Piece] |= b;
575 if (b & ei.kingZone[Us])
577 ei.kingAttackersCount[Us]++;
578 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
579 Bitboard bb = (b & ei.attackedBy[Them][KING]);
581 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
585 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
586 : count_1s<HasPopCnt>(b & no_mob_area));
588 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
590 // Decrease score if we are attacked by an enemy pawn. Remaining part
591 // of threat evaluation must be done later when we have full attack info.
592 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
593 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
595 // Bishop and knight outposts squares
596 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
597 evaluate_outposts<Piece, Us>(pos, ei, s);
599 // Special patterns: trapped bishops on a7/h7/a2/h2
600 // and trapped bishops on a1/h1/a8/h8 in Chess960.
603 if (bit_is_set(MaskA7H7[Us], s))
604 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
606 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
607 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
610 // Queen or rook on 7th rank
611 if ( (Piece == ROOK || Piece == QUEEN)
612 && relative_rank(Us, s) == RANK_7
613 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
615 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
618 // Special extra evaluation for rooks
621 // Open and half-open files
623 if (ei.pi->file_is_half_open(Us, f))
625 if (ei.pi->file_is_half_open(Them, f))
626 ei.value += Sign[Us] * RookOpenFileBonus;
628 ei.value += Sign[Us] * RookHalfOpenFileBonus;
631 // Penalize rooks which are trapped inside a king. Penalize more if
632 // king has lost right to castle.
633 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
636 ksq = pos.king_square(Us);
638 if ( square_file(ksq) >= FILE_E
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_right(Us, square_file(ksq)))
644 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
645 : (TrappedRookPenalty - mob * 16), 0);
647 else if ( square_file(ksq) <= FILE_D
648 && square_file(s) < square_file(ksq)
649 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
651 // Is there a half-open file between the king and the edge of the board?
652 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
653 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
654 : (TrappedRookPenalty - mob * 16), 0);
661 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
662 // and the type of attacked one.
665 void evaluate_threats(const Position& pos, EvalInfo& ei) {
667 const Color Them = (Us == WHITE ? BLACK : WHITE);
670 Score bonus = make_score(0, 0);
672 // Enemy pieces not defended by a pawn and under our attack
673 Bitboard weakEnemies = pos.pieces_of_color(Them)
674 & ~ei.attackedBy[Them][PAWN]
675 & ei.attackedBy[Us][0];
679 // Add bonus according to type of attacked enemy pieces and to the
680 // type of attacking piece, from knights to queens. Kings are not
681 // considered because are already special handled in king evaluation.
682 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
684 b = ei.attackedBy[Us][pt1] & weakEnemies;
686 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
687 if (b & pos.pieces(pt2))
688 bonus += ThreatBonus[pt1][pt2];
690 ei.value += Sign[Us] * bonus;
694 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
695 // pieces of a given color.
697 template<Color Us, bool HasPopCnt>
698 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
700 const Color Them = (Us == WHITE ? BLACK : WHITE);
702 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
703 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
705 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
706 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
707 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
708 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
710 // Sum up all attacked squares
711 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
712 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
713 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
717 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
719 template<Color Us, bool HasPopCnt>
720 void evaluate_king(const Position& pos, EvalInfo& ei) {
722 const Color Them = (Us == WHITE ? BLACK : WHITE);
724 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
727 int attackUnits, count, shelter = 0;
728 const Square s = pos.king_square(Us);
731 if (relative_rank(Us, s) <= RANK_4)
733 shelter = ei.pi->get_king_shelter(pos, Us, s);
734 ei.value += Sign[Us] * make_score(shelter, 0);
737 // King safety. This is quite complicated, and is almost certainly far
738 // from optimally tuned.
739 if ( pos.piece_count(Them, QUEEN) >= 1
740 && ei.kingAttackersCount[Them] >= 2
741 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
742 && ei.kingAdjacentZoneAttacksCount[Them])
744 // Is it the attackers turn to move?
745 sente = (Them == pos.side_to_move());
747 // Find the attacked squares around the king which has no defenders
748 // apart from the king itself
749 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
750 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
751 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
752 | ei.attacked_by(Us, QUEEN));
754 // Initialize the 'attackUnits' variable, which is used later on as an
755 // index to the SafetyTable[] array. The initial value is based on the
756 // number and types of the attacking pieces, the number of attacked and
757 // undefended squares around the king, the square of the king, and the
758 // quality of the pawn shelter.
759 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
760 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
761 + InitKingDanger[relative_square(Us, s)]
764 // Analyse safe queen contact checks
765 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
768 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
769 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
771 b &= attackedByOthers;
773 // Squares attacked by the queen and supported by another enemy piece and
774 // not defended by other pieces but our king.
777 // The bitboard b now contains the squares available for safe queen
779 count = count_1s_max_15<HasPopCnt>(b);
780 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
782 // Is there a mate threat?
783 if (QueenContactMates && !pos.is_check())
785 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
786 occ = pos.occupied_squares();
789 to = pop_1st_bit(&b);
791 // Do we have escape squares from queen contact check attack ?
792 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
794 // We have a mate, unless the queen is pinned or there
795 // is an X-ray attack through the queen.
796 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
798 from = pos.piece_list(Them, QUEEN, i);
799 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
800 && !bit_is_set(pos.pinned_pieces(Them), from)
801 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
802 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
804 // Set the mate threat move
805 ei.mateThreat[Them] = make_move(from, to);
813 // Analyse safe distance checks
814 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
816 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
818 b = pos.attacks_from<ROOK>(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, ROOK);
828 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
830 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
832 b = pos.attacks_from<BISHOP>(s) & safe;
835 b2 = b & ei.attacked_by(Them, QUEEN);
837 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
840 b2 = b & ei.attacked_by(Them, BISHOP);
842 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
844 if (KnightCheckBonus > 0)
846 b = pos.attacks_from<KNIGHT>(s) & safe;
849 b2 = b & ei.attacked_by(Them, KNIGHT);
851 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
854 // Analyse discovered checks (only for non-pawns right now, consider
855 // adding pawns later).
856 if (DiscoveredCheckBonus)
858 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
860 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
863 // Has a mate threat been found? We don't do anything here if the
864 // side with the mating move is the side to move, because in that
865 // case the mating side will get a huge bonus at the end of the main
866 // evaluation function instead.
867 if (ei.mateThreat[Them] != MOVE_NONE)
868 attackUnits += MateThreatBonus;
870 // Ensure that attackUnits is between 0 and 99, in order to avoid array
871 // out of bounds errors.
872 attackUnits = Min(99, Max(0, attackUnits));
874 // Finally, extract the king safety score from the SafetyTable[] array.
875 // Add the score to the evaluation, and also to ei.futilityMargin. The
876 // reason for adding the king safety score to the futility margin is
877 // that the king safety scores can sometimes be very big, and that
878 // capturing a single attacking piece can therefore result in a score
879 // change far bigger than the value of the captured piece.
880 Score v = apply_weight(make_score(SafetyTable[attackUnits], 0), WeightKingSafety[Us]);
882 ei.value -= Sign[Us] * v;
884 if (Us == pos.side_to_move())
885 ei.futilityMargin += mg_value(v);
890 // evaluate_passed_pawns() evaluates the passed pawns of the given color
893 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
895 const Color Them = (Us == WHITE ? BLACK : WHITE);
898 Square ourKingSq = pos.king_square(Us);
899 Square theirKingSq = pos.king_square(Them);
900 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
904 Square s = pop_1st_bit(&b);
906 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
907 assert(pos.pawn_is_passed(Us, s));
909 int r = int(relative_rank(Us, s) - RANK_2);
910 int tr = Max(0, r * (r - 1));
912 // Base bonus based on rank
913 Value mbonus = Value(20 * tr);
914 Value ebonus = Value(10 + r * r * 10);
916 // Adjust bonus based on king proximity
919 Square blockSq = s + pawn_push(Us);
921 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
922 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
923 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
925 // If the pawn is free to advance, increase bonus
926 if (pos.square_is_empty(blockSq))
928 // There are no enemy pawns in the pawn's path
929 b2 = squares_in_front_of(Us, s);
931 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
933 // Squares attacked by us
934 b4 = b2 & ei.attacked_by(Us);
936 // Squares attacked or occupied by enemy pieces
937 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
939 // If there is an enemy rook or queen attacking the pawn from behind,
940 // add all X-ray attacks by the rook or queen.
941 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
942 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
945 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
946 if (b3 == EmptyBoardBB)
947 // No enemy attacks or pieces, huge bonus!
948 // Even bigger if we protect the pawn's path
949 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
951 // OK, there are enemy attacks or pieces (but not pawns). Are those
952 // squares which are attacked by the enemy also attacked by us ?
953 // If yes, big bonus (but smaller than when there are no enemy attacks),
954 // if no, somewhat smaller bonus.
955 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
957 // At last, add a small bonus when there are no *friendly* pieces
958 // in the pawn's path.
959 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
964 // If the pawn is supported by a friendly pawn, increase bonus
965 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
967 ebonus += Value(r * 20);
968 else if (pos.attacks_from<PAWN>(s, Them) & b2)
969 ebonus += Value(r * 12);
971 // If the other side has only a king, check whether the pawn is
973 if (pos.non_pawn_material(Them) == Value(0))
978 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
979 d = square_distance(s, qsq)
980 - square_distance(theirKingSq, qsq)
981 + (Us != pos.side_to_move());
985 int mtg = RANK_8 - relative_rank(Us, s);
986 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
989 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
997 // Rook pawns are a special case: They are sometimes worse, and
998 // sometimes better than other passed pawns. It is difficult to find
999 // good rules for determining whether they are good or bad. For now,
1000 // we try the following: Increase the value for rook pawns if the
1001 // other side has no pieces apart from a knight, and decrease the
1002 // value if the other side has a rook or queen.
1003 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1005 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1006 && pos.piece_count(Them, KNIGHT) <= 1)
1007 ebonus += ebonus / 4;
1008 else if (pos.pieces(ROOK, QUEEN, Them))
1009 ebonus -= ebonus / 4;
1012 // Add the scores for this pawn to the middle game and endgame eval.
1013 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);
1019 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1021 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1023 int movesToGo[2] = {0, 0};
1024 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1026 // Evaluate pawns for each color
1027 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1028 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1030 // Neither side has an unstoppable passed pawn?
1031 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1034 // Does only one side have an unstoppable passed pawn?
1035 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1037 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1038 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1041 { // Both sides have unstoppable pawns! Try to find out who queens
1042 // first. We begin by transforming 'movesToGo' to the number of
1043 // plies until the pawn queens for both sides.
1044 movesToGo[WHITE] *= 2;
1045 movesToGo[BLACK] *= 2;
1046 movesToGo[pos.side_to_move()]--;
1048 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1049 Color loserSide = opposite_color(winnerSide);
1051 // If one side queens at least three plies before the other, that side wins
1052 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1053 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1055 // If one side queens one ply before the other and checks the king or attacks
1056 // the undefended opponent's queening square, that side wins. To avoid cases
1057 // where the opponent's king could move somewhere before first pawn queens we
1058 // consider only free paths to queen for both pawns.
1059 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1060 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1062 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1064 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1065 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1067 Bitboard b = pos.occupied_squares();
1068 clear_bit(&b, pawnToGo[winnerSide]);
1069 clear_bit(&b, pawnToGo[loserSide]);
1070 b = queen_attacks_bb(winnerQSq, b);
1072 if ( (b & pos.pieces(KING, loserSide))
1073 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1074 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1080 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1081 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1084 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1086 assert(square_is_ok(s));
1087 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1089 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1090 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1092 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1093 && pos.see(s, b6) < 0
1094 && pos.see(s, b8) < 0)
1096 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1101 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1102 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1103 // black), and assigns a penalty if it is. This pattern can obviously
1104 // only occur in Chess960 games.
1106 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1108 Piece pawn = piece_of_color_and_type(us, PAWN);
1112 assert(square_is_ok(s));
1113 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1115 if (square_file(s) == FILE_A)
1117 b2 = relative_square(us, SQ_B2);
1118 b3 = relative_square(us, SQ_B3);
1119 c3 = relative_square(us, SQ_C3);
1123 b2 = relative_square(us, SQ_G2);
1124 b3 = relative_square(us, SQ_G3);
1125 c3 = relative_square(us, SQ_F3);
1128 if (pos.piece_on(b2) == pawn)
1132 if (!pos.square_is_empty(b3))
1133 penalty = 2 * TrappedBishopA1H1Penalty;
1134 else if (pos.piece_on(c3) == pawn)
1135 penalty = TrappedBishopA1H1Penalty;
1137 penalty = TrappedBishopA1H1Penalty / 2;
1139 ei.value -= Sign[us] * penalty;
1144 // evaluate_space() computes the space evaluation for a given side. The
1145 // space evaluation is a simple bonus based on the number of safe squares
1146 // available for minor pieces on the central four files on ranks 2--4. Safe
1147 // squares one, two or three squares behind a friendly pawn are counted
1148 // twice. Finally, the space bonus is scaled by a weight taken from the
1149 // material hash table.
1150 template<Color Us, bool HasPopCnt>
1151 void evaluate_space(const Position& pos, EvalInfo& ei) {
1153 const Color Them = (Us == WHITE ? BLACK : WHITE);
1155 // Find the safe squares for our pieces inside the area defined by
1156 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1157 // pawn, or if it is undefended and attacked by an enemy piece.
1159 Bitboard safeSquares = SpaceMask[Us]
1160 & ~pos.pieces(PAWN, Us)
1161 & ~ei.attacked_by(Them, PAWN)
1162 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1164 // Find all squares which are at most three squares behind some friendly
1166 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1167 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1168 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1170 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1171 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1173 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), WeightSpace);
1177 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1179 inline Score apply_weight(Score v, Score w) {
1180 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1184 // scale_by_game_phase() interpolates between a middle game and an endgame
1185 // score, based on game phase. It also scales the return value by a
1186 // ScaleFactor array.
1188 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1190 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1191 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1192 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1194 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1196 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1197 return Value(result & ~(GrainSize - 1));
1201 // weight_option() computes the value of an evaluation weight, by combining
1202 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1204 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1206 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1208 // Convert to integer to prevent overflow
1209 int mg = mg_value(uciWeight);
1210 int eg = eg_value(uciWeight);
1212 mg = (mg * 0x100) / 100;
1213 eg = (eg * 0x100) / 100;
1214 mg = (mg * mg_value(internalWeight)) / 0x100;
1215 eg = (eg * eg_value(internalWeight)) / 0x100;
1216 return make_score(mg, eg);
1219 // init_safety() initizes the king safety evaluation, based on UCI
1220 // parameters. It is called from read_weights().
1222 void init_safety() {
1224 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1225 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1226 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1227 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1228 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1229 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1230 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1232 int maxSlope = get_option_value_int("King Safety Max Slope");
1233 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1234 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1235 double b = get_option_value_int("King Safety X Intercept");
1236 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1237 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1239 for (int i = 0; i < 100; i++)
1242 SafetyTable[i] = Value(0);
1244 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1246 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1249 for (int i = 0; i < 100; i++)
1251 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1252 for (int j = i + 1; j < 100; j++)
1253 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1255 if (SafetyTable[i] > Value(peak))
1256 SafetyTable[i] = Value(peak);