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[][] contains bonus according to which piece type
134 // attacks which one.
137 const Score ThreatBonus[8][8] = {
138 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
139 { Z, S(18,37), Z, S(37,47), S(55,97), S(55,97), Z, Z }, // KNIGHT attacks
140 { Z, S(18,37), S(37,47), Z, S(55,97), S(55,97), Z, Z }, // BISHOP attacks
141 { Z, S( 9,27), S(27,47), S(27,47), Z, S(37,47), Z, Z }, // ROOK attacks
142 { Z, S(27,37), S(27,37), S(27,37), S(27,37), Z, Z, Z }, // QUEEN attacks
143 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
144 { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
145 { Z, Z, Z, Z, Z, Z, Z, Z } // not used
148 // ThreatedByPawnPenalty[] contains a penalty according to which piece
149 // type is attacked by an enemy pawn.
150 const Score ThreatedByPawnPenalty[8] = {
151 Z, Z, S(56, 70), S(56, 70), S(76, 99), S(86, 118), Z, Z
157 // Bonus for unstoppable passed pawns
158 const Value UnstoppablePawnValue = Value(0x500);
160 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
161 const Score RookOn7thBonus = make_score(47, 98);
162 const Score QueenOn7thBonus = make_score(27, 54);
164 // Rooks on open files (modified by Joona Kiiski)
165 const Score RookOpenFileBonus = make_score(43, 43);
166 const Score RookHalfOpenFileBonus = make_score(19, 19);
168 // Penalty for rooks trapped inside a friendly king which has lost the
170 const Value TrappedRookPenalty = Value(180);
172 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
174 const Score TrappedBishopA7H7Penalty = make_score(300, 300);
176 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
177 const Bitboard MaskA7H7[2] = {
178 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
179 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
182 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
183 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
184 // happen in Chess960 games.
185 const Score TrappedBishopA1H1Penalty = make_score(100, 100);
187 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
188 const Bitboard MaskA1H1[2] = {
189 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
190 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
193 // The SpaceMask[color] contains the area of the board which is considered
194 // by the space evaluation. In the middle game, each side is given a bonus
195 // based on how many squares inside this area are safe and available for
196 // friendly minor pieces.
197 const Bitboard SpaceMask[2] = {
198 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
199 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
200 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
201 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
202 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
203 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
206 /// King danger constants and variables. The king danger scores are taken
207 /// from the KingDangerTable[]. Various little "meta-bonuses" measuring
208 /// the strength of the enemy attack are added up into an integer, which
209 /// is used as an index to KingDangerTable[].
211 // Attack weights for each piece type and table indexed on piece type
212 const int QueenAttackWeight = 5;
213 const int RookAttackWeight = 3;
214 const int BishopAttackWeight = 2;
215 const int KnightAttackWeight = 2;
217 const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
219 // Bonuses for safe checks
220 const int QueenContactCheckBonus = 3;
221 const int DiscoveredCheckBonus = 3;
222 const int QueenCheckBonus = 2;
223 const int RookCheckBonus = 1;
224 const int BishopCheckBonus = 1;
225 const int KnightCheckBonus = 1;
227 // Scan for queen contact mates?
228 const bool QueenContactMates = true;
230 // Bonus for having a mate threat
231 const int MateThreatBonus = 3;
233 // InitKingDanger[] contains bonuses based on the position of the defending
235 const int InitKingDanger[64] = {
236 2, 0, 2, 5, 5, 2, 0, 2,
237 2, 2, 4, 8, 8, 4, 2, 2,
238 7, 10, 12, 12, 12, 12, 10, 7,
239 15, 15, 15, 15, 15, 15, 15, 15,
240 15, 15, 15, 15, 15, 15, 15, 15,
241 15, 15, 15, 15, 15, 15, 15, 15,
242 15, 15, 15, 15, 15, 15, 15, 15,
243 15, 15, 15, 15, 15, 15, 15, 15
246 // KingDangerTable[color][] contains the actual king danger weighted scores
247 Score KingDangerTable[2][128];
249 // Pawn and material hash tables, indexed by the current thread id.
250 // Note that they will be initialized at 0 being global variables.
251 MaterialInfoTable* MaterialTable[MAX_THREADS];
252 PawnInfoTable* PawnTable[MAX_THREADS];
254 // Sizes of pawn and material hash tables
255 const int PawnTableSize = 16384;
256 const int MaterialTableSize = 1024;
258 // Function prototypes
259 template<bool HasPopCnt>
260 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
262 template<Color Us, bool HasPopCnt>
263 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
265 template<Color Us, bool HasPopCnt>
266 void evaluate_king(const Position& pos, EvalInfo& ei);
269 void evaluate_threats(const Position& pos, EvalInfo& ei);
271 template<Color Us, bool HasPopCnt>
272 void evaluate_space(const Position& pos, EvalInfo& ei);
275 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
277 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
278 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
279 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
280 inline Score apply_weight(Score v, Score weight);
281 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
282 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
291 /// evaluate() is the main evaluation function. It always computes two
292 /// values, an endgame score and a middle game score, and interpolates
293 /// between them based on the remaining material.
294 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
296 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
297 : do_evaluate<false>(pos, ei, threadID);
302 template<bool HasPopCnt>
303 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
306 ScaleFactor factor[2];
309 assert(threadID >= 0 && threadID < MAX_THREADS);
310 assert(!pos.is_check());
312 memset(&ei, 0, sizeof(EvalInfo));
314 // Initialize by reading the incrementally updated scores included in the
315 // position object (material + piece square tables)
316 ei.value = pos.value();
318 // Probe the material hash table
319 ei.mi = MaterialTable[threadID]->get_material_info(pos);
320 ei.value += ei.mi->material_value();
322 // If we have a specialized evaluation function for the current material
323 // configuration, call it and return
324 if (ei.mi->specialized_eval_exists())
325 return ei.mi->evaluate(pos);
327 // After get_material_info() call that modifies them
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->pawns_value(), Weights[PawnStructure]);
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 b = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
345 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b)/2;
347 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
348 b = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
350 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b)/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 including king
363 evaluate_threats<WHITE>(pos, ei);
364 evaluate_threats<BLACK>(pos, ei);
366 // Evaluate passed pawns, we need full attack info including king
367 evaluate_passed_pawns<WHITE>(pos, ei);
368 evaluate_passed_pawns<BLACK>(pos, ei);
370 // If one side has only a king, check whether exsists any unstoppable passed pawn
371 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
372 evaluate_unstoppable_pawns(pos, ei);
374 Phase phase = ei.mi->game_phase();
376 // Middle-game specific evaluation terms
377 if (phase > PHASE_ENDGAME)
379 // Pawn storms in positions with opposite castling
380 if ( square_file(pos.king_square(WHITE)) >= FILE_E
381 && square_file(pos.king_square(BLACK)) <= FILE_D)
383 ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
385 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
386 && square_file(pos.king_square(BLACK)) >= FILE_E)
388 ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
390 // Evaluate space for both sides
391 if (ei.mi->space_weight() > 0)
393 evaluate_space<WHITE, HasPopCnt>(pos, ei);
394 evaluate_space<BLACK, HasPopCnt>(pos, ei);
399 ei.value += apply_weight(ei.mobility, Weights[Mobility]);
401 // If we don't already have an unusual scale factor, check for opposite
402 // colored bishop endgames, and use a lower scale for those
403 if ( phase < PHASE_MIDGAME
404 && pos.opposite_colored_bishops()
405 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > Value(0))
406 || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < Value(0))))
410 // Only the two bishops ?
411 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
412 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
414 // Check for KBP vs KB with only a single pawn that is almost
415 // certainly a draw or at least two pawns.
416 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
417 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
420 // Endgame with opposite-colored bishops, but also other pieces. Still
421 // a bit drawish, but not as drawish as with only the two bishops.
422 sf = ScaleFactor(50);
424 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
426 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
430 // Interpolate between the middle game and the endgame score
431 Color stm = pos.side_to_move();
433 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
435 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
440 /// init_eval() initializes various tables used by the evaluation function
442 void init_eval(int threads) {
444 assert(threads <= MAX_THREADS);
446 for (int i = 0; i < MAX_THREADS; i++)
451 delete MaterialTable[i];
453 MaterialTable[i] = NULL;
457 PawnTable[i] = new PawnInfoTable(PawnTableSize);
458 if (!MaterialTable[i])
459 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
464 /// quit_eval() releases heap-allocated memory at program termination
468 for (int i = 0; i < MAX_THREADS; i++)
471 delete MaterialTable[i];
473 MaterialTable[i] = NULL;
478 /// read_weights() reads evaluation weights from the corresponding UCI parameters
480 void read_weights(Color us) {
482 // King safety is asymmetrical. Our king danger level is weighted by
483 // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
484 const int kingDangerUs = (us == WHITE ? KingDangerUs : KingDangerThem);
485 const int kingDangerThem = (us == WHITE ? KingDangerThem : KingDangerUs);
487 Weights[Mobility] = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
488 Weights[PawnStructure] = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
489 Weights[PassedPawns] = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
490 Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
491 Weights[kingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
492 Weights[kingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
494 // If running in analysis mode, make sure we use symmetrical king safety. We do this
495 // by replacing both Weights[kingDangerUs] and Weights[kingDangerThem] by their average.
496 if (get_option_value_bool("UCI_AnalyseMode"))
497 Weights[kingDangerUs] = Weights[kingDangerThem] = (Weights[kingDangerUs] + Weights[kingDangerThem]) / 2;
505 // evaluate_outposts() evaluates bishop and knight outposts squares
507 template<PieceType Piece, Color Us>
508 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
510 const Color Them = (Us == WHITE ? BLACK : WHITE);
512 // Initial bonus based on square
513 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
514 : KnightOutpostBonus[relative_square(Us, s)]);
516 // Increase bonus if supported by pawn, especially if the opponent has
517 // no minor piece which can exchange the outpost piece
518 if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
520 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
521 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
522 bonus += bonus + bonus / 2;
526 ei.value += Sign[Us] * make_score(bonus, bonus);
530 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
532 template<PieceType Piece, Color Us, bool HasPopCnt>
533 void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
540 const Color Them = (Us == WHITE ? BLACK : WHITE);
541 const Square* ptr = pos.piece_list_begin(Us, Piece);
543 while ((s = *ptr++) != SQ_NONE)
545 // Find attacked squares, including x-ray attacks for bishops and rooks
546 if (Piece == KNIGHT || Piece == QUEEN)
547 b = pos.attacks_from<Piece>(s);
548 else if (Piece == BISHOP)
549 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
550 else if (Piece == ROOK)
551 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
555 // Update attack info
556 ei.attackedBy[Us][Piece] |= b;
559 if (b & ei.kingZone[Us])
561 ei.kingAttackersCount[Us]++;
562 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
563 Bitboard bb = (b & ei.attackedBy[Them][KING]);
565 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
569 mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
570 : count_1s<HasPopCnt>(b & no_mob_area));
572 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
574 // Decrease score if we are attacked by an enemy pawn. Remaining part
575 // of threat evaluation must be done later when we have full attack info.
576 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
577 ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
579 // Bishop and knight outposts squares
580 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
581 evaluate_outposts<Piece, Us>(pos, ei, s);
583 // Special patterns: trapped bishops on a7/h7/a2/h2
584 // and trapped bishops on a1/h1/a8/h8 in Chess960.
587 if (bit_is_set(MaskA7H7[Us], s))
588 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
590 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
591 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
594 // Queen or rook on 7th rank
595 if ( (Piece == ROOK || Piece == QUEEN)
596 && relative_rank(Us, s) == RANK_7
597 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
599 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
602 // Special extra evaluation for rooks
605 // Open and half-open files
607 if (ei.pi->file_is_half_open(Us, f))
609 if (ei.pi->file_is_half_open(Them, f))
610 ei.value += Sign[Us] * RookOpenFileBonus;
612 ei.value += Sign[Us] * RookHalfOpenFileBonus;
615 // Penalize rooks which are trapped inside a king. Penalize more if
616 // king has lost right to castle.
617 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
620 ksq = pos.king_square(Us);
622 if ( square_file(ksq) >= FILE_E
623 && square_file(s) > square_file(ksq)
624 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
626 // Is there a half-open file between the king and the edge of the board?
627 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
628 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
629 : (TrappedRookPenalty - mob * 16), 0);
631 else if ( square_file(ksq) <= FILE_D
632 && square_file(s) < square_file(ksq)
633 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
635 // Is there a half-open file between the king and the edge of the board?
636 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
637 ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
638 : (TrappedRookPenalty - mob * 16), 0);
645 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
646 // and the type of attacked one.
649 void evaluate_threats(const Position& pos, EvalInfo& ei) {
651 const Color Them = (Us == WHITE ? BLACK : WHITE);
654 Score bonus = make_score(0, 0);
656 // Enemy pieces not defended by a pawn and under our attack
657 Bitboard weakEnemies = pos.pieces_of_color(Them)
658 & ~ei.attackedBy[Them][PAWN]
659 & ei.attackedBy[Us][0];
663 // Add bonus according to type of attacked enemy pieces and to the
664 // type of attacking piece, from knights to queens. Kings are not
665 // considered because are already special handled in king evaluation.
666 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
668 b = ei.attackedBy[Us][pt1] & weakEnemies;
670 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
671 if (b & pos.pieces(pt2))
672 bonus += ThreatBonus[pt1][pt2];
674 ei.value += Sign[Us] * bonus;
678 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
679 // pieces of a given color.
681 template<Color Us, bool HasPopCnt>
682 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
684 const Color Them = (Us == WHITE ? BLACK : WHITE);
686 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
687 const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
689 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
690 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
691 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
692 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
694 // Sum up all attacked squares
695 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
696 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
697 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
701 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
703 template<Color Us, bool HasPopCnt>
704 void evaluate_king(const Position& pos, EvalInfo& ei) {
706 const Color Them = (Us == WHITE ? BLACK : WHITE);
708 Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b2, safe;
711 int attackUnits, count, shelter = 0;
712 const Square s = pos.king_square(Us);
715 if (relative_rank(Us, s) <= RANK_4)
717 shelter = ei.pi->get_king_shelter(pos, Us, s);
718 ei.value += Sign[Us] * make_score(shelter, 0);
721 // King safety. This is quite complicated, and is almost certainly far
722 // from optimally tuned.
723 if ( pos.piece_count(Them, QUEEN) >= 1
724 && ei.kingAttackersCount[Them] >= 2
725 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
726 && ei.kingAdjacentZoneAttacksCount[Them])
728 // Is it the attackers turn to move?
729 sente = (Them == pos.side_to_move());
731 // Find the attacked squares around the king which has no defenders
732 // apart from the king itself
733 undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
734 undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
735 | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
736 | ei.attacked_by(Us, QUEEN));
738 // Initialize the 'attackUnits' variable, which is used later on as an
739 // index to the KingDangerTable[] array. The initial value is based on
740 // the number and types of the enemy's attacking pieces, the number of
741 // attacked and undefended squares around our king, the square of the
742 // king, and the quality of the pawn shelter.
743 attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
744 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
745 + InitKingDanger[relative_square(Us, s)]
748 // Analyse safe queen contact checks
749 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
752 attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
753 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
755 b &= attackedByOthers;
757 // Squares attacked by the queen and supported by another enemy piece and
758 // not defended by other pieces but our king.
761 // The bitboard b now contains the squares available for safe queen
763 count = count_1s_max_15<HasPopCnt>(b);
764 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
766 // Is there a mate threat?
767 if (QueenContactMates && !pos.is_check())
769 escapeSquares = pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
770 occ = pos.occupied_squares();
773 to = pop_1st_bit(&b);
775 // Do we have escape squares from queen contact check attack ?
776 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
778 // We have a mate, unless the queen is pinned or there
779 // is an X-ray attack through the queen.
780 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
782 from = pos.piece_list(Them, QUEEN, i);
783 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
784 && !bit_is_set(pos.pinned_pieces(Them), from)
785 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
786 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
788 // Set the mate threat move
789 ei.mateThreat[Them] = make_move(from, to);
797 // Analyse safe distance checks
798 safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
800 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
802 b = pos.attacks_from<ROOK>(s) & safe;
805 b2 = b & ei.attacked_by(Them, QUEEN);
807 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
810 b2 = b & ei.attacked_by(Them, ROOK);
812 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
814 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
816 b = pos.attacks_from<BISHOP>(s) & safe;
819 b2 = b & ei.attacked_by(Them, QUEEN);
821 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
824 b2 = b & ei.attacked_by(Them, BISHOP);
826 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
828 if (KnightCheckBonus > 0)
830 b = pos.attacks_from<KNIGHT>(s) & safe;
833 b2 = b & ei.attacked_by(Them, KNIGHT);
835 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
838 // Analyse discovered checks (only for non-pawns right now, consider
839 // adding pawns later).
840 if (DiscoveredCheckBonus)
842 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
844 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
847 // Has a mate threat been found? We don't do anything here if the
848 // side with the mating move is the side to move, because in that
849 // case the mating side will get a huge bonus at the end of the main
850 // evaluation function instead.
851 if (ei.mateThreat[Them] != MOVE_NONE)
852 attackUnits += MateThreatBonus;
854 // Ensure that attackUnits is between 0 and 99, in order to avoid array
855 // out of bounds errors.
856 attackUnits = Min(99, Max(0, attackUnits));
858 // Finally, extract the king danger score from the KingDangerTable[] array.
859 // Subtract the score from evaluation, and set ei.futilityMargin[].
860 // The reason for storing the king danger score to futility margin
861 // is that the king danger scores can sometimes be very big, and that
862 // capturing a single attacking piece can therefore result in a score
863 // change far bigger than the value of the captured piece.
864 ei.value -= Sign[Us] * KingDangerTable[Us][attackUnits];
865 ei.futilityMargin[Us] = mg_value(KingDangerTable[Us][attackUnits]);
870 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
873 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
875 const Color Them = (Us == WHITE ? BLACK : WHITE);
877 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us);
881 Square s = pop_1st_bit(&b);
883 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
884 assert(pos.pawn_is_passed(Us, s));
886 int r = int(relative_rank(Us, s) - RANK_2);
887 int tr = Max(0, r * (r - 1));
889 // Base bonus based on rank
890 Value mbonus = Value(20 * tr);
891 Value ebonus = Value(10 + r * r * 10);
893 // Adjust bonus based on king proximity
896 Square blockSq = s + pawn_push(Us);
898 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * tr);
899 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * tr);
900 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
902 // If the pawn is free to advance, increase bonus
903 if (pos.square_is_empty(blockSq))
905 // There are no enemy pawns in the pawn's path
906 Bitboard b2 = squares_in_front_of(Us, s);
908 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
910 // Squares attacked by us
911 Bitboard b4 = b2 & ei.attacked_by(Us);
913 // Squares attacked or occupied by enemy pieces
914 Bitboard b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
916 // If there is an enemy rook or queen attacking the pawn from behind,
917 // add all X-ray attacks by the rook or queen.
918 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
919 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
922 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
923 if (b3 == EmptyBoardBB)
924 // No enemy attacks or pieces, huge bonus!
925 // Even bigger if we protect the pawn's path
926 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
928 // OK, there are enemy attacks or pieces (but not pawns). Are those
929 // squares which are attacked by the enemy also attacked by us ?
930 // If yes, big bonus (but smaller than when there are no enemy attacks),
931 // if no, somewhat smaller bonus.
932 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
934 // At last, add a small bonus when there are no *friendly* pieces
935 // in the pawn's path.
936 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
941 // If the pawn is supported by a friendly pawn, increase bonus
942 Bitboard b1 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
944 ebonus += Value(r * 20);
945 else if (pos.attacks_from<PAWN>(s, Them) & b1)
946 ebonus += Value(r * 12);
948 // Rook pawns are a special case: They are sometimes worse, and
949 // sometimes better than other passed pawns. It is difficult to find
950 // good rules for determining whether they are good or bad. For now,
951 // we try the following: Increase the value for rook pawns if the
952 // other side has no pieces apart from a knight, and decrease the
953 // value if the other side has a rook or queen.
954 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
956 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
957 && pos.piece_count(Them, KNIGHT) <= 1)
958 ebonus += ebonus / 4;
959 else if (pos.pieces(ROOK, QUEEN, Them))
960 ebonus -= ebonus / 4;
963 // Add the scores for this pawn to the middle game and endgame eval
964 ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), Weights[PassedPawns]);
970 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides
972 void evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
974 int movesToGo[2] = {0, 0};
975 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
977 for (Color c = WHITE; c <= BLACK; c++)
979 // Skip evaluation if other side has non-pawn pieces
980 if (pos.non_pawn_material(opposite_color(c)))
983 Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(c);
987 Square s = pop_1st_bit(&b);
988 Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8));
989 int d = square_distance(s, queeningSquare)
990 - square_distance(pos.king_square(opposite_color(c)), queeningSquare)
991 + int(c != pos.side_to_move());
995 int mtg = RANK_8 - relative_rank(c, s);
996 int blockerCount = count_1s_max_15(squares_in_front_of(c, s) & pos.occupied_squares());
999 if (d < 0 && (!movesToGo[c] || movesToGo[c] > mtg))
1008 // Neither side has an unstoppable passed pawn?
1009 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1012 // Does only one side have an unstoppable passed pawn?
1013 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1015 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1016 ei.value += make_score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1019 { // Both sides have unstoppable pawns! Try to find out who queens
1020 // first. We begin by transforming 'movesToGo' to the number of
1021 // plies until the pawn queens for both sides.
1022 movesToGo[WHITE] *= 2;
1023 movesToGo[BLACK] *= 2;
1024 movesToGo[pos.side_to_move()]--;
1026 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1027 Color loserSide = opposite_color(winnerSide);
1029 // If one side queens at least three plies before the other, that side wins
1030 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1031 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1033 // If one side queens one ply before the other and checks the king or attacks
1034 // the undefended opponent's queening square, that side wins. To avoid cases
1035 // where the opponent's king could move somewhere before first pawn queens we
1036 // consider only free paths to queen for both pawns.
1037 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1038 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1040 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1042 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1043 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1045 Bitboard b = pos.occupied_squares();
1046 clear_bit(&b, pawnToGo[winnerSide]);
1047 clear_bit(&b, pawnToGo[loserSide]);
1048 b = queen_attacks_bb(winnerQSq, b);
1050 if ( (b & pos.pieces(KING, loserSide))
1051 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1052 ei.value += Sign[winnerSide] * make_score(0, UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
1058 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1059 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1062 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1064 assert(square_is_ok(s));
1065 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1067 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1068 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1070 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1071 && pos.see(s, b6) < 0
1072 && pos.see(s, b8) < 0)
1074 ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
1079 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1080 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1081 // black), and assigns a penalty if it is. This pattern can obviously
1082 // only occur in Chess960 games.
1084 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1086 Piece pawn = piece_of_color_and_type(us, PAWN);
1090 assert(square_is_ok(s));
1091 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1093 if (square_file(s) == FILE_A)
1095 b2 = relative_square(us, SQ_B2);
1096 b3 = relative_square(us, SQ_B3);
1097 c3 = relative_square(us, SQ_C3);
1101 b2 = relative_square(us, SQ_G2);
1102 b3 = relative_square(us, SQ_G3);
1103 c3 = relative_square(us, SQ_F3);
1106 if (pos.piece_on(b2) == pawn)
1110 if (!pos.square_is_empty(b3))
1111 penalty = 2 * TrappedBishopA1H1Penalty;
1112 else if (pos.piece_on(c3) == pawn)
1113 penalty = TrappedBishopA1H1Penalty;
1115 penalty = TrappedBishopA1H1Penalty / 2;
1117 ei.value -= Sign[us] * penalty;
1122 // evaluate_space() computes the space evaluation for a given side. The
1123 // space evaluation is a simple bonus based on the number of safe squares
1124 // available for minor pieces on the central four files on ranks 2--4. Safe
1125 // squares one, two or three squares behind a friendly pawn are counted
1126 // twice. Finally, the space bonus is scaled by a weight taken from the
1127 // material hash table.
1128 template<Color Us, bool HasPopCnt>
1129 void evaluate_space(const Position& pos, EvalInfo& ei) {
1131 const Color Them = (Us == WHITE ? BLACK : WHITE);
1133 // Find the safe squares for our pieces inside the area defined by
1134 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1135 // pawn, or if it is undefended and attacked by an enemy piece.
1137 Bitboard safeSquares = SpaceMask[Us]
1138 & ~pos.pieces(PAWN, Us)
1139 & ~ei.attacked_by(Them, PAWN)
1140 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1142 // Find all squares which are at most three squares behind some friendly
1144 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1145 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1146 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1148 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1149 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1151 ei.value += Sign[Us] * apply_weight(make_score(space * ei.mi->space_weight(), 0), Weights[Space]);
1155 // apply_weight() applies an evaluation weight to a value trying to prevent overflow
1157 inline Score apply_weight(Score v, Score w) {
1158 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
1162 // scale_by_game_phase() interpolates between a middle game and an endgame
1163 // score, based on game phase. It also scales the return value by a
1164 // ScaleFactor array.
1166 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1168 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1169 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1170 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1172 Value ev = apply_scale_factor(eg_value(v), sf[(eg_value(v) > Value(0) ? WHITE : BLACK)]);
1174 int result = (mg_value(v) * ph + ev * (128 - ph)) / 128;
1175 return Value(result & ~(GrainSize - 1));
1179 // weight_option() computes the value of an evaluation weight, by combining
1180 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1182 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1184 Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
1186 // Convert to integer to prevent overflow
1187 int mg = mg_value(uciWeight);
1188 int eg = eg_value(uciWeight);
1190 mg = (mg * 0x100) / 100;
1191 eg = (eg * 0x100) / 100;
1192 mg = (mg * mg_value(internalWeight)) / 0x100;
1193 eg = (eg * eg_value(internalWeight)) / 0x100;
1194 return make_score(mg, eg);
1197 // init_safety() initizes the king safety evaluation, based on UCI
1198 // parameters. It is called from read_weights().
1200 void init_safety() {
1208 // First setup the base table
1209 for (int i = 0; i < 100; i++)
1214 t[i] = Value((int)(a * (i - b) * (i - b)));
1217 for (int i = 1; i < 100; i++)
1219 if (t[i] - t[i - 1] > maxSlope)
1220 t[i] = t[i - 1] + Value(maxSlope);
1222 if (t[i] > Value(peak))
1226 // Then apply the weights and get the final KingDangerTable[] array
1227 for (Color c = WHITE; c <= BLACK; c++)
1228 for (int i = 0; i < 100; i++)
1229 KingDangerTable[c][i] = apply_weight(make_score(t[i], 0), Weights[KingDangerUs + c]);