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 enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
53 #define S(mg, eg) make_score(mg, eg)
55 // Internal evaluation weights. These are applied on top of the evaluation
56 // weights read from UCI parameters. The purpose is to be able to change
57 // the evaluation weights while keeping the default values of the UCI
58 // parameters at 100, which looks prettier.
60 // Values modified by Joona Kiiski
61 const Score WeightsInternal[] = {
62 S(248, 271), S(233, 201), S(252, 259), S(46, 0), S(247, 0), S(259, 0)
65 // Knight mobility bonus in middle game and endgame, indexed by the number
66 // of attacked squares not occupied by friendly piecess.
67 const Score KnightMobilityBonus[16] = {
68 S(-38,-33), S(-25,-23), S(-12,-13), S( 0,-3),
69 S( 12, 7), S( 25, 17), S( 31, 22), S(38, 27), S(38, 27)
72 // Bishop mobility bonus in middle game and endgame, indexed by the number
73 // of attacked squares not occupied by friendly pieces. X-ray attacks through
74 // queens are also included.
75 const Score BishopMobilityBonus[16] = {
76 S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12),
77 S( 31, 26), S( 45, 40), S(57, 52), S(65, 60),
78 S( 71, 65), S( 74, 69), S(76, 71), S(78, 73),
79 S( 79, 74), S( 80, 75), S(81, 76), S(81, 76)
82 // Rook mobility bonus in middle game and endgame, indexed by the number
83 // of attacked squares not occupied by friendly pieces. X-ray attacks through
84 // queens and rooks are also included.
85 const Score RookMobilityBonus[16] = {
86 S(-20,-36), S(-14,-19), S(-8, -3), S(-2, 13),
87 S( 4, 29), S( 10, 46), S(14, 62), S(19, 79),
88 S( 23, 95), S( 26,106), S(27,111), S(28,114),
89 S( 29,116), S( 30,117), S(31,118), S(32,118)
92 // Queen mobility bonus in middle game and endgame, indexed by the number
93 // of attacked squares not occupied by friendly pieces.
94 const Score QueenMobilityBonus[32] = {
95 S(-10,-18), S(-8,-13), S(-6, -7), S(-3, -2), S(-1, 3), S( 1, 8),
96 S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
97 S( 16, 35), S(17, 35), S(18, 35), S(20, 35), S(20, 35), S(20, 35),
98 S( 20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
99 S( 20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
100 S( 20, 35), S(20, 35)
103 // Pointers table to access mobility tables through piece type
104 const Score* MobilityBonus[8] = { 0, 0, KnightMobilityBonus, BishopMobilityBonus,
105 RookMobilityBonus, QueenMobilityBonus, 0, 0 };
107 // Outpost bonuses for knights and bishops, indexed by square (from white's
109 const Value KnightOutpostBonus[64] = {
111 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
112 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
113 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
114 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
115 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
116 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
117 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
118 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
121 const Value BishopOutpostBonus[64] = {
123 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
124 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
125 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
126 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
127 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
128 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
129 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
130 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
133 // ThreatBonus[attacking][attacked] contains bonus according to which
134 // piece type attacks which one.
135 const Score ThreatBonus[8][8] = {
137 { S(0, 0), S(18,37), S( 0, 0), S(37,47), S(55,97), S(55,97) }, // KNIGHT
138 { S(0, 0), S(18,37), S(37,47), S( 0, 0), S(55,97), S(55,97) }, // BISHOP
139 { S(0, 0), S( 9,27), S(27,47), S(27,47), S( 0, 0), S(37,47) }, // ROOK
140 { S(0, 0), S(27,37), S(27,37), S(27,37), S(27,37), S( 0, 0) }, // QUEEN
144 // ThreatedByPawnPenalty[] contains a penalty according to which piece
145 // type is attacked by an enemy pawn.
146 const Score ThreatedByPawnPenalty[8] = {
147 S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
152 // Bonus for unstoppable passed pawns
153 const Value UnstoppablePawnValue = Value(0x500);
155 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
156 const Score RookOn7thBonus = make_score(47, 98);
157 const Score QueenOn7thBonus = make_score(27, 54);
159 // Rooks on open files (modified by Joona Kiiski)
160 const Score RookOpenFileBonus = make_score(43, 43);
161 const Score RookHalfOpenFileBonus = make_score(19, 19);
163 // Penalty for rooks trapped inside a friendly king which has lost the
165 const Value TrappedRookPenalty = Value(180);
167 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
169 const Score TrappedBishopA7H7Penalty = make_score(300, 300);
171 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
172 const Bitboard MaskA7H7[2] = {
173 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
174 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
177 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
178 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
179 // happen in Chess960 games.
180 const Score TrappedBishopA1H1Penalty = make_score(100, 100);
182 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
183 const Bitboard MaskA1H1[2] = {
184 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
185 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
188 // The SpaceMask[color] contains the area of the board which is considered
189 // by the space evaluation. In the middle game, each side is given a bonus
190 // based on how many squares inside this area are safe and available for
191 // friendly minor pieces.
192 const Bitboard SpaceMask[2] = {
193 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
194 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
195 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
196 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
197 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
198 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
201 /// King danger constants and variables. The king danger scores are taken
202 /// from the KingDangerTable[]. Various little "meta-bonuses" measuring
203 /// the strength of the enemy attack are added up into an integer, which
204 /// is used as an index to KingDangerTable[].
206 // KingAttackWeights[] contains king attack weights by piece type
207 const int KingAttackWeights[8] = { 0, 0, 2, 2, 3, 5 };
209 // Bonuses for enemy's safe checks
210 const int QueenContactCheckBonus = 3;
211 const int DiscoveredCheckBonus = 3;
212 const int QueenCheckBonus = 2;
213 const int RookCheckBonus = 1;
214 const int BishopCheckBonus = 1;
215 const int KnightCheckBonus = 1;
217 // Scan for queen contact mates?
218 const bool QueenContactMates = true;
220 // Bonus for having a mate threat
221 const int MateThreatBonus = 3;
223 // InitKingDanger[] contains bonuses based on the position of the defending
225 const int InitKingDanger[64] = {
226 2, 0, 2, 5, 5, 2, 0, 2,
227 2, 2, 4, 8, 8, 4, 2, 2,
228 7, 10, 12, 12, 12, 12, 10, 7,
229 15, 15, 15, 15, 15, 15, 15, 15,
230 15, 15, 15, 15, 15, 15, 15, 15,
231 15, 15, 15, 15, 15, 15, 15, 15,
232 15, 15, 15, 15, 15, 15, 15, 15,
233 15, 15, 15, 15, 15, 15, 15, 15
236 // KingDangerTable[color][] contains the actual king danger weighted scores
237 Score KingDangerTable[2][128];
239 // Pawn and material hash tables, indexed by the current thread id.
240 // Note that they will be initialized at 0 being global variables.
241 MaterialInfoTable* MaterialTable[MAX_THREADS];
242 PawnInfoTable* PawnTable[MAX_THREADS];
244 // Sizes of pawn and material hash tables
245 const int PawnTableSize = 16384;
246 const int MaterialTableSize = 1024;
248 // Function prototypes
249 template<bool HasPopCnt>
250 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
252 template<Color Us, bool HasPopCnt>
253 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
255 template<Color Us, bool HasPopCnt>
256 void evaluate_king(const Position& pos, EvalInfo& ei);
259 void evaluate_threats(const Position& pos, EvalInfo& ei);
261 template<Color Us, bool HasPopCnt>
262 void evaluate_space(const Position& pos, EvalInfo& ei);
265 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
267 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
268 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
269 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
270 inline Score apply_weight(Score v, Score weight);
271 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
272 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
281 /// evaluate() is the main evaluation function. It always computes two
282 /// values, an endgame score and a middle game score, and interpolates
283 /// between them based on the remaining material.
284 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
286 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
287 : do_evaluate<false>(pos, ei, threadID);
292 template<bool HasPopCnt>
293 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
296 ScaleFactor factor[2];
299 assert(threadID >= 0 && threadID < MAX_THREADS);
300 assert(!pos.is_check());
302 memset(&ei, 0, sizeof(EvalInfo));
304 // Initialize by reading the incrementally updated scores included in the
305 // position object (material + piece square tables)
306 ei.value = pos.value();
308 // Probe the material hash table
309 ei.mi = MaterialTable[threadID]->get_material_info(pos);
310 ei.value += ei.mi->material_value();
312 // If we have a specialized evaluation function for the current material
313 // configuration, call it and return
314 if (ei.mi->specialized_eval_exists())
315 return ei.mi->evaluate(pos);
317 // After get_material_info() call that modifies them
318 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
319 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
321 // Probe the pawn hash table
322 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
323 ei.value += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
325 // Initialize king attack bitboards and king attack zones for both sides
326 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
327 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
328 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
329 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
331 // Initialize pawn attack bitboards for both sides
332 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
333 b = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
335 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b)/2;
337 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
338 b = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
340 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b)/2;
343 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
344 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
346 // Kings. Kings are evaluated after all other pieces for both sides,
347 // because we need complete attack information for all pieces when computing
348 // the king safety evaluation.
349 evaluate_king<WHITE, HasPopCnt>(pos, ei);
350 evaluate_king<BLACK, HasPopCnt>(pos, ei);
352 // Evaluate tactical threats, we need full attack info including king
353 evaluate_threats<WHITE>(pos, ei);
354 evaluate_threats<BLACK>(pos, ei);
356 // Evaluate passed pawns, we need full attack info including king
357 evaluate_passed_pawns<WHITE>(pos, ei);
358 evaluate_passed_pawns<BLACK>(pos, ei);
360 // If one side has only a king, check whether exsists any unstoppable passed pawn
361 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
362 evaluate_unstoppable_pawns(pos, ei);
364 Phase phase = ei.mi->game_phase();
366 // Middle-game specific evaluation terms
367 if (phase > PHASE_ENDGAME)
369 // Pawn storms in positions with opposite castling
370 if ( square_file(pos.king_square(WHITE)) >= FILE_E
371 && square_file(pos.king_square(BLACK)) <= FILE_D)
373 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
375 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
376 && square_file(pos.king_square(BLACK)) >= FILE_E)
378 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
380 // Evaluate space for both sides
381 if (ei.mi->space_weight() > 0)
383 evaluate_space<WHITE, HasPopCnt>(pos, ei);
384 evaluate_space<BLACK, HasPopCnt>(pos, ei);
389 ei.value += apply_weight(ei.mobility, Weights[Mobility]);
391 // If we don't already have an unusual scale factor, check for opposite
392 // colored bishop endgames, and use a lower scale for those
393 if ( phase < PHASE_MIDGAME
394 && pos.opposite_colored_bishops()
395 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
396 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
400 // Only the two bishops ?
401 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
402 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
404 // Check for KBP vs KB with only a single pawn that is almost
405 // certainly a draw or at least two pawns.
406 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
407 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
410 // Endgame with opposite-colored bishops, but also other pieces. Still
411 // a bit drawish, but not as drawish as with only the two bishops.
412 sf = ScaleFactor(50);
414 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
416 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
420 // Interpolate between the middle game and the endgame score
421 Color stm = pos.side_to_move();
423 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
425 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
430 /// init_eval() initializes various tables used by the evaluation function
432 void init_eval(int threads) {
434 assert(threads <= MAX_THREADS);
436 for (int i = 0; i < MAX_THREADS; i++)
441 delete MaterialTable[i];
443 MaterialTable[i] = NULL;
447 PawnTable[i] = new PawnInfoTable(PawnTableSize);
448 if (!MaterialTable[i])
449 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
454 /// quit_eval() releases heap-allocated memory at program termination
458 for (int i = 0; i < MAX_THREADS; i++)
461 delete MaterialTable[i];
463 MaterialTable[i] = NULL;
468 /// read_weights() reads evaluation weights from the corresponding UCI parameters
470 void read_weights(Color us) {
472 // King safety is asymmetrical. Our king danger level is weighted by
473 // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
474 const int kingDangerUs = (us == WHITE ? KingDangerUs : KingDangerThem);
475 const int kingDangerThem = (us == WHITE ? KingDangerThem : KingDangerUs);
477 Weights[Mobility] = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
478 Weights[PawnStructure] = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
479 Weights[PassedPawns] = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
480 Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
481 Weights[kingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
482 Weights[kingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
484 // If running in analysis mode, make sure we use symmetrical king safety. We do this
485 // by replacing both Weights[kingDangerUs] and Weights[kingDangerThem] by their average.
486 if (get_option_value_bool("UCI_AnalyseMode"))
487 Weights[kingDangerUs] = Weights[kingDangerThem] = (Weights[kingDangerUs] + Weights[kingDangerThem]) / 2;
495 // evaluate_outposts() evaluates bishop and knight outposts squares
497 template<PieceType Piece, Color Us>
498 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
500 const Color Them = (Us == WHITE ? BLACK : WHITE);
502 // Initial bonus based on square
503 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
504 : KnightOutpostBonus[relative_square(Us, s)]);
506 // Increase bonus if supported by pawn, especially if the opponent has
507 // no minor piece which can exchange the outpost piece
508 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
510 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
511 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
512 bonus += bonus + bonus / 2;
516 ei.value += Sign[Us] * make_score(bonus, bonus);
520 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
522 template<PieceType Piece, Color Us, bool HasPopCnt>
523 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
530 const Color Them = (Us == WHITE ? BLACK : WHITE);
531 const Square* ptr = pos.piece_list_begin(Us, Piece);
533 while ((s = *ptr++) != SQ_NONE)
535 // Find attacked squares, including x-ray attacks for bishops and rooks
536 if (Piece == KNIGHT || Piece == QUEEN)
537 b = pos.attacks_from<Piece>(s);
538 else if (Piece == BISHOP)
539 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
540 else if (Piece == ROOK)
541 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
545 // Update attack info
546 ei.attackedBy[Us][Piece] |= b;
549 if (b & ei.kingZone[Us])
551 ei.kingAttackersCount[Us]++;
552 ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
553 Bitboard bb = (b & ei.attackedBy[Them][KING]);
555 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
559 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
560 : count_1s<HasPopCnt>(b & no_mob_area));
562 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
564 // Decrease score if we are attacked by an enemy pawn. Remaining part
565 // of threat evaluation must be done later when we have full attack info.
566 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
567 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
569 // Bishop and knight outposts squares
570 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
571 evaluate_outposts<Piece, Us>(pos, ei, s);
573 // Special patterns: trapped bishops on a7/h7/a2/h2
574 // and trapped bishops on a1/h1/a8/h8 in Chess960.
577 if (bit_is_set(MaskA7H7[Us], s))
578 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
580 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
581 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
584 // Queen or rook on 7th rank
585 if ( (Piece == ROOK || Piece == QUEEN)
586 && relative_rank(Us, s) == RANK_7
587 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
589 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
592 // Special extra evaluation for rooks
595 // Open and half-open files
597 if (ei.pi->file_is_half_open(Us, f))
599 if (ei.pi->file_is_half_open(Them, f))
600 ei.value += Sign[Us] * RookOpenFileBonus;
602 ei.value += Sign[Us] * RookHalfOpenFileBonus;
605 // Penalize rooks which are trapped inside a king. Penalize more if
606 // king has lost right to castle.
607 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
610 ksq = pos.king_square(Us);
612 if ( square_file(ksq) >= FILE_E
613 && square_file(s) > square_file(ksq)
614 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
616 // Is there a half-open file between the king and the edge of the board?
617 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
618 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
619 : (TrappedRookPenalty - mob * 16), 0);
621 else if ( square_file(ksq) <= FILE_D
622 && square_file(s) < square_file(ksq)
623 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
625 // Is there a half-open file between the king and the edge of the board?
626 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
627 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
628 : (TrappedRookPenalty - mob * 16), 0);
635 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
636 // and the type of attacked one.
639 void evaluate_threats(const Position& pos, EvalInfo& ei) {
641 const Color Them = (Us == WHITE ? BLACK : WHITE);
644 Score bonus = make_score(0, 0);
646 // Enemy pieces not defended by a pawn and under our attack
647 Bitboard weakEnemies = pos.pieces_of_color(Them)
648 & ~ei.attackedBy[Them][PAWN]
649 & ei.attackedBy[Us][0];
653 // Add bonus according to type of attacked enemy pieces and to the
654 // type of attacking piece, from knights to queens. Kings are not
655 // considered because are already special handled in king evaluation.
656 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
658 b = ei.attackedBy[Us][pt1] & weakEnemies;
660 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
661 if (b & pos.pieces(pt2))
662 bonus += ThreatBonus[pt1][pt2];
664 ei.value += Sign[Us] * bonus;
668 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
669 // pieces of a given color.
671 template<Color Us, bool HasPopCnt>
672 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
674 const Color Them = (Us == WHITE ? BLACK : WHITE);
676 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
677 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
679 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
680 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
681 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
682 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
684 // Sum up all attacked squares
685 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
686 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
687 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
691 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
693 template<Color Us, bool HasPopCnt>
694 void evaluate_king(const Position& pos, EvalInfo& ei) {
696 const Color Them = (Us == WHITE ? BLACK : WHITE);
698 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b1, b2, safe;
701 int attackUnits, shelter = 0;
702 const Square ksq = pos.king_square(Us);
705 if (relative_rank(Us, ksq) <= RANK_4)
707 shelter = ei.pi->get_king_shelter(pos, Us, ksq);
708 ei.value += Sign[Us] * make_score(shelter, 0);
711 // King safety. This is quite complicated, and is almost certainly far
712 // from optimally tuned.
713 if ( pos.piece_count(Them, QUEEN) >= 1
714 && ei.kingAttackersCount[Them] >= 2
715 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
716 && ei.kingAdjacentZoneAttacksCount[Them])
718 // Is it the attackers turn to move?
719 sente = (Them == pos.side_to_move());
721 // Find the attacked squares around the king which has no defenders
722 // apart from the king itself
723 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
724 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
725 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
726 | ei.attacked_by(Us, QUEEN));
728 // Initialize the 'attackUnits' variable, which is used later on as an
729 // index to the KingDangerTable[] array. The initial value is based on
730 // the number and types of the enemy's attacking pieces, the number of
731 // attacked and undefended squares around our king, the square of the
732 // king, and the quality of the pawn shelter.
733 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
734 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
735 + InitKingDanger[relative_square(Us, ksq)]
738 // Analyse safe queen contact checks
739 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
742 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
743 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
745 b &= attackedByOthers;
747 // Squares attacked by the queen and supported by another enemy piece and
748 // not defended by other pieces but our king.
751 // The bitboard b now contains the squares available for safe queen
753 attackUnits += QueenContactCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
755 // Is there a mate threat?
756 if (QueenContactMates && !pos.is_check())
758 escapeSquares = pos.attacks_from<KING>(ksq) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
759 occ = pos.occupied_squares();
762 to = pop_1st_bit(&b);
764 // Do we have escape squares from queen contact check attack ?
765 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[ksq])))
767 // We have a mate, unless the queen is pinned or there
768 // is an X-ray attack through the queen.
769 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
771 from = pos.piece_list(Them, QUEEN, i);
772 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
773 && !bit_is_set(pos.pinned_pieces(Them), from)
774 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
775 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
777 // Set the mate threat move
778 ei.mateThreat[Them] = make_move(from, to);
786 // Analyse enemy's safe distance checks
787 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
789 b1 = pos.attacks_from<ROOK>(ksq) & safe;
790 b2 = pos.attacks_from<BISHOP>(ksq) & safe;
792 // Enemy rooks safe checks
793 b = b1 & ei.attacked_by(Them, ROOK);
795 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b);
797 // Enemy bishops safe checks
798 b = b2 & ei.attacked_by(Them, BISHOP);
800 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b);
802 // Enemy queens safe checks
803 b = (b1 | b2) & ei.attacked_by(Them, QUEEN);
805 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
807 // Enemy knights safe checks
808 b = pos.attacks_from<KNIGHT>(ksq) & ei.attacked_by(Them, KNIGHT) & safe;
810 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b);
812 // Analyse discovered checks (only for non-pawns right now, consider
813 // adding pawns later).
814 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
816 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
818 // Has a mate threat been found? We don't do anything here if the
819 // side with the mating move is the side to move, because in that
820 // case the mating side will get a huge bonus at the end of the main
821 // evaluation function instead.
822 if (ei.mateThreat[Them] != MOVE_NONE)
823 attackUnits += MateThreatBonus;
825 // Ensure that attackUnits is between 0 and 99, in order to avoid array
826 // out of bounds errors.
827 attackUnits = Min(99, Max(0, attackUnits));
829 // Finally, extract the king danger score from the KingDangerTable[]
830 // array and subtract the score from evaluation. Set also ei.kingDanger[]
831 // value that will be used for pruning because this value can sometimes
832 // be very big, and so capturing a single attacking piece can therefore
833 // result in a score change far bigger than the value of the captured piece.
834 ei.value -= Sign[Us] * KingDangerTable[Us][attackUnits];
835 ei.kingDanger[Us] = mg_value(KingDangerTable[Us][attackUnits]);
840 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
843 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
845 const Color Them = (Us == WHITE ? BLACK : WHITE);
847 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us);
851 Square s = pop_1st_bit(&b);
853 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
854 assert(pos.pawn_is_passed(Us, s));
856 int r = int(relative_rank(Us, s) - RANK_2);
857 int tr = Max(0, r * (r - 1));
859 // Base bonus based on rank
860 Value mbonus = Value(20 * tr);
861 Value ebonus = Value(10 + r * r * 10);
863 // Adjust bonus based on king proximity
866 Square blockSq = s + pawn_push(Us);
868 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * tr);
869 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * tr);
870 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
872 // If the pawn is free to advance, increase bonus
873 if (pos.square_is_empty(blockSq))
875 // There are no enemy pawns in the pawn's path
876 Bitboard b2 = squares_in_front_of(Us, s);
878 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
880 // Squares attacked by us
881 Bitboard b4 = b2 & ei.attacked_by(Us);
883 // Squares attacked or occupied by enemy pieces
884 Bitboard b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
886 // If there is an enemy rook or queen attacking the pawn from behind,
887 // add all X-ray attacks by the rook or queen.
888 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
889 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
892 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
893 if (b3 == EmptyBoardBB)
894 // No enemy attacks or pieces, huge bonus!
895 // Even bigger if we protect the pawn's path
896 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
898 // OK, there are enemy attacks or pieces (but not pawns). Are those
899 // squares which are attacked by the enemy also attacked by us ?
900 // If yes, big bonus (but smaller than when there are no enemy attacks),
901 // if no, somewhat smaller bonus.
902 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
904 // At last, add a small bonus when there are no *friendly* pieces
905 // in the pawn's path.
906 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
911 // If the pawn is supported by a friendly pawn, increase bonus
912 Bitboard b1 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
914 ebonus += Value(r * 20);
915 else if (pos.attacks_from<PAWN>(s, Them) & b1)
916 ebonus += Value(r * 12);
918 // Rook pawns are a special case: They are sometimes worse, and
919 // sometimes better than other passed pawns. It is difficult to find
920 // good rules for determining whether they are good or bad. For now,
921 // we try the following: Increase the value for rook pawns if the
922 // other side has no pieces apart from a knight, and decrease the
923 // value if the other side has a rook or queen.
924 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
926 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
927 && pos.piece_count(Them, KNIGHT) <= 1)
928 ebonus += ebonus / 4;
929 else if (pos.pieces(ROOK, QUEEN, Them))
930 ebonus -= ebonus / 4;
933 // Add the scores for this pawn to the middle game and endgame eval
934 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), Weights[PassedPawns]);
940 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides
942 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
944 int movesToGo[2] = {0, 0};
945 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
947 for (Color c = WHITE; c <= BLACK; c++)
949 // Skip evaluation if other side has non-pawn pieces
950 if (pos.non_pawn_material(opposite_color(c)))
953 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(c);
957 Square s = pop_1st_bit(&b);
958 Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8));
959 int d = square_distance(s, queeningSquare)
960 - square_distance(pos.king_square(opposite_color(c)), queeningSquare)
961 + int(c != pos.side_to_move());
965 int mtg = RANK_8 - relative_rank(c, s);
966 int blockerCount = count_1s_max_15(squares_in_front_of(c, s) & pos.occupied_squares());
969 if (d < 0 && (!movesToGo[c] || movesToGo[c] > mtg))
978 // Neither side has an unstoppable passed pawn?
979 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
982 // Does only one side have an unstoppable passed pawn?
983 if (!movesToGo[WHITE] || !movesToGo[BLACK])
985 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
986 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
989 { // Both sides have unstoppable pawns! Try to find out who queens
990 // first. We begin by transforming 'movesToGo' to the number of
991 // plies until the pawn queens for both sides.
992 movesToGo[WHITE] *= 2;
993 movesToGo[BLACK] *= 2;
994 movesToGo[pos.side_to_move()]--;
996 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
997 Color loserSide = opposite_color(winnerSide);
999 // If one side queens at least three plies before the other, that side wins
1000 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1001 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1003 // If one side queens one ply before the other and checks the king or attacks
1004 // the undefended opponent's queening square, that side wins. To avoid cases
1005 // where the opponent's king could move somewhere before first pawn queens we
1006 // consider only free paths to queen for both pawns.
1007 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1008 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1010 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1012 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1013 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1015 Bitboard b = pos.occupied_squares();
1016 clear_bit(&b, pawnToGo[winnerSide]);
1017 clear_bit(&b, pawnToGo[loserSide]);
1018 b = queen_attacks_bb(winnerQSq, b);
1020 if ( (b & pos.pieces(KING, loserSide))
1021 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1022 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1028 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1029 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1032 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1034 assert(square_is_ok(s));
1035 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1037 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1038 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1040 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1041 && pos.see(s, b6) < 0
1042 && pos.see(s, b8) < 0)
1044 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1049 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1050 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1051 // black), and assigns a penalty if it is. This pattern can obviously
1052 // only occur in Chess960 games.
1054 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1056 Piece pawn = piece_of_color_and_type(us, PAWN);
1060 assert(square_is_ok(s));
1061 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1063 if (square_file(s) == FILE_A)
1065 b2 = relative_square(us, SQ_B2);
1066 b3 = relative_square(us, SQ_B3);
1067 c3 = relative_square(us, SQ_C3);
1071 b2 = relative_square(us, SQ_G2);
1072 b3 = relative_square(us, SQ_G3);
1073 c3 = relative_square(us, SQ_F3);
1076 if (pos.piece_on(b2) == pawn)
1080 if (!pos.square_is_empty(b3))
1081 penalty = 2 * TrappedBishopA1H1Penalty;
1082 else if (pos.piece_on(c3) == pawn)
1083 penalty = TrappedBishopA1H1Penalty;
1085 penalty = TrappedBishopA1H1Penalty / 2;
1087 ei.value -= Sign[us] * penalty;
1092 // evaluate_space() computes the space evaluation for a given side. The
1093 // space evaluation is a simple bonus based on the number of safe squares
1094 // available for minor pieces on the central four files on ranks 2--4. Safe
1095 // squares one, two or three squares behind a friendly pawn are counted
1096 // twice. Finally, the space bonus is scaled by a weight taken from the
1097 // material hash table.
1098 template<Color Us, bool HasPopCnt>
1099 void evaluate_space(const Position& pos, EvalInfo& ei) {
1101 const Color Them = (Us == WHITE ? BLACK : WHITE);
1103 // Find the safe squares for our pieces inside the area defined by
1104 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1105 // pawn, or if it is undefended and attacked by an enemy piece.
1107 Bitboard safeSquares = SpaceMask[Us]
1108 & ~pos.pieces(PAWN, Us)
1109 & ~ei.attacked_by(Them, PAWN)
1110 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1112 // Find all squares which are at most three squares behind some friendly
1114 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1115 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1116 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1118 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1119 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1121 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), Weights[Space]);
1125 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1127 inline Score apply_weight(Score v, Score w) {
1128 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1132 // scale_by_game_phase() interpolates between a middle game and an endgame
1133 // score, based on game phase. It also scales the return value by a
1134 // ScaleFactor array.
1136 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1138 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1139 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1140 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1142 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1144 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1145 return Value(result & ~(GrainSize - 1));
1149 // weight_option() computes the value of an evaluation weight, by combining
1150 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1152 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1154 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1156 // Convert to integer to prevent overflow
1157 int mg = mg_value(uciWeight);
1158 int eg = eg_value(uciWeight);
1160 mg = (mg * 0x100) / 100;
1161 eg = (eg * 0x100) / 100;
1162 mg = (mg * mg_value(internalWeight)) / 0x100;
1163 eg = (eg * eg_value(internalWeight)) / 0x100;
1164 return make_score(mg, eg);
1167 // init_safety() initizes the king safety evaluation, based on UCI
1168 // parameters. It is called from read_weights().
1170 void init_safety() {
1178 // First setup the base table
1179 for (int i = 0; i < 100; i++)
1184 t[i] = Value((int)(a * (i - b) * (i - b)));
1187 for (int i = 1; i < 100; i++)
1189 if (t[i] - t[i - 1] > maxSlope)
1190 t[i] = t[i - 1] + Value(maxSlope);
1192 if (t[i] > Value(peak))
1196 // Then apply the weights and get the final KingDangerTable[] array
1197 for (Color c = WHITE; c <= BLACK; c++)
1198 for (int i = 0; i < 100; i++)
1199 KingDangerTable[c][i] = apply_weight(make_score(t[i], 0), Weights[KingDangerUs + c]);