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 int WeightMobilityMidgame, WeightMobilityEndgame;
50 int WeightPawnStructureMidgame, WeightPawnStructureEndgame;
51 int WeightPassedPawnsMidgame, WeightPassedPawnsEndgame;
52 int WeightKingSafety[2];
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 int WeightMobilityMidgameInternal = 248;
62 const int WeightMobilityEndgameInternal = 271;
63 const int WeightPawnStructureMidgameInternal = 233;
64 const int WeightPawnStructureEndgameInternal = 201;
65 const int WeightPassedPawnsMidgameInternal = 252;
66 const int WeightPassedPawnsEndgameInternal = 259;
67 const int WeightKingSafetyInternal = 247;
68 const int WeightKingOppSafetyInternal = 259;
69 const int WeightSpaceInternal = 46;
71 // Mobility and outposts bonus modified by Joona Kiiski
73 // Visually better to define tables constants
77 // Knight mobility bonus in middle game and endgame, indexed by the number
78 // of attacked squares not occupied by friendly piecess.
79 const Score KnightMobilityBonus[] = {
80 S(-38,-33), S(-25,-23), S(-12,-13), S( 0,-3),
81 S( 12, 7), S( 25, 17), S( 31, 22), S(38, 27), S(38, 27)
84 // Bishop mobility bonus in middle game and endgame, indexed by the number
85 // of attacked squares not occupied by friendly pieces. X-ray attacks through
86 // queens are also included.
87 const Score BishopMobilityBonus[] = {
88 S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12),
89 S( 31, 26), S( 45, 40), S(57, 52), S(65, 60),
90 S( 71, 65), S( 74, 69), S(76, 71), S(78, 73),
91 S( 79, 74), S( 80, 75), S(81, 76), S(81, 76)
94 // Rook mobility bonus in middle game and endgame, indexed by the number
95 // of attacked squares not occupied by friendly pieces. X-ray attacks through
96 // queens and rooks are also included.
97 const Score RookMobilityBonus[] = {
98 S(-20,-36), S(-14,-19), S(-8, -3), S(-2, 13),
99 S( 4, 29), S( 10, 46), S(14, 62), S(19, 79),
100 S( 23, 95), S( 26,106), S(27,111), S(28,114),
101 S( 29,116), S( 30,117), S(31,118), S(32,118)
104 // Queen mobility bonus in middle game and endgame, indexed by the number
105 // of attacked squares not occupied by friendly pieces.
106 const Score QueenMobilityBonus[] = {
107 S(-10,-18), S(-8,-13), S(-6, -7), S(-3, -2), S(-1, 3), S( 1, 8),
108 S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
109 S( 16, 35), S(17, 35), S(18, 35), S(20, 35), S(20, 35), S(20, 35),
110 S( 20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
111 S( 20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35), S(20, 35),
112 S( 20, 35), S(20, 35)
115 // Pointers table to access mobility tables through piece type
116 const Score* MobilityBonus[] = { 0, 0, KnightMobilityBonus, BishopMobilityBonus, RookMobilityBonus, QueenMobilityBonus };
118 // Outpost bonuses for knights and bishops, indexed by square (from white's
120 const Value KnightOutpostBonus[64] = {
122 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
123 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
124 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
125 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
126 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
127 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
128 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
129 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
132 const Value BishopOutpostBonus[64] = {
134 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
135 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
136 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
137 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
138 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
139 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
140 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
141 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
144 // Bonus for unstoppable passed pawns
145 const Value UnstoppablePawnValue = Value(0x500);
147 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
148 const Score RookOn7thBonus = Score(47, 98);
149 const Score QueenOn7thBonus = Score(27, 54);
151 // Rooks on open files (modified by Joona Kiiski)
152 const Value RookOpenFileBonus = Value(43);
153 const Value RookHalfOpenFileBonus = Value(19);
155 // Penalty for rooks trapped inside a friendly king which has lost the
157 const Value TrappedRookPenalty = Value(180);
159 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
161 const Value TrappedBishopA7H7Penalty = Value(300);
163 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
164 const Bitboard MaskA7H7[2] = {
165 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
166 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
169 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
170 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
171 // happen in Chess960 games.
172 const Value TrappedBishopA1H1Penalty = Value(100);
174 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
175 const Bitboard MaskA1H1[2] = {
176 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
177 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
180 // The SpaceMask[color] contains the area of the board which is considered
181 // by the space evaluation. In the middle game, each side is given a bonus
182 // based on how many squares inside this area are safe and available for
183 // friendly minor pieces.
184 const Bitboard SpaceMask[2] = {
185 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
186 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
187 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
188 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
189 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
190 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
193 /// King safety constants and variables. The king safety scores are taken
194 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
195 /// the strength of the attack are added up into an integer, which is used
196 /// as an index to SafetyTable[].
198 // Attack weights for each piece type and table indexed on piece type
199 const int QueenAttackWeight = 5;
200 const int RookAttackWeight = 3;
201 const int BishopAttackWeight = 2;
202 const int KnightAttackWeight = 2;
204 const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
206 // Bonuses for safe checks, initialized from UCI options
207 int QueenContactCheckBonus, DiscoveredCheckBonus;
208 int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
210 // Scan for queen contact mates?
211 const bool QueenContactMates = true;
213 // Bonus for having a mate threat, initialized from UCI options
216 // ThreatBonus[][] contains bonus according to which piece type
217 // attacks which one.
218 const Value MidgameThreatBonus[8][8] = {
219 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
220 { V(0),V(18), V(0),V(37), V(55), V(55), V(0), V(0) }, // KNIGHT attacks
221 { V(0),V(18),V(37), V(0), V(55), V(55), V(0), V(0) }, // BISHOP attacks
222 { V(0), V(9),V(27),V(27), V(0), V(37), V(0), V(0) }, // ROOK attacks
223 { V(0),V(27),V(27),V(27), V(27), V(0), V(0), V(0) }, // QUEEN attacks
224 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
225 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
226 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) } // not used
229 const Value EndgameThreatBonus[8][8] = {
230 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
231 { V(0),V(37), V(0),V(47), V(97), V(97), V(0), V(0) }, // KNIGHT attacks
232 { V(0),V(37),V(47), V(0), V(97), V(97), V(0), V(0) }, // BISHOP attacks
233 { V(0),V(27),V(47),V(47), V(0), V(47), V(0), V(0) }, // ROOK attacks
234 { V(0),V(37),V(37),V(37), V(37), V(0), V(0), V(0) }, // QUEEN attacks
235 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
236 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
237 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) } // not used
240 // ThreatedByPawnPenalty[] contains a penalty according to which piece
241 // type is attacked by an enemy pawn.
242 const Value MidgameThreatedByPawnPenalty[8] = {
243 V(0), V(0), V(56), V(56), V(76), V(86), V(0), V(0)
246 const Value EndgameThreatedByPawnPenalty[8] = {
247 V(0), V(0), V(70), V(70), V(99), V(118), V(0), V(0)
250 // InitKingDanger[] contains bonuses based on the position of the defending
252 const int InitKingDanger[64] = {
253 2, 0, 2, 5, 5, 2, 0, 2,
254 2, 2, 4, 8, 8, 4, 2, 2,
255 7, 10, 12, 12, 12, 12, 10, 7,
256 15, 15, 15, 15, 15, 15, 15, 15,
257 15, 15, 15, 15, 15, 15, 15, 15,
258 15, 15, 15, 15, 15, 15, 15, 15,
259 15, 15, 15, 15, 15, 15, 15, 15,
260 15, 15, 15, 15, 15, 15, 15, 15
263 // SafetyTable[] contains the actual king safety scores. It is initialized
265 Value SafetyTable[100];
267 // Pawn and material hash tables, indexed by the current thread id
268 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
269 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
271 // Sizes of pawn and material hash tables
272 const int PawnTableSize = 16384;
273 const int MaterialTableSize = 1024;
275 // Function prototypes
276 template<bool HasPopCnt>
277 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
279 template<Color Us, bool HasPopCnt>
280 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
282 template<Color Us, bool HasPopCnt>
283 void evaluate_king(const Position& pos, EvalInfo& ei);
286 void evaluate_threats(const Position& pos, EvalInfo& ei);
288 template<Color Us, bool HasPopCnt>
289 void evaluate_space(const Position& pos, EvalInfo& ei);
291 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
292 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
293 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
294 inline Score apply_weight(Score v, int wmg, int weg);
295 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
296 int weight_option(const std::string& opt, int weight);
305 /// evaluate() is the main evaluation function. It always computes two
306 /// values, an endgame score and a middle game score, and interpolates
307 /// between them based on the remaining material.
308 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
310 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
311 : do_evaluate<false>(pos, ei, threadID);
316 template<bool HasPopCnt>
317 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
320 assert(threadID >= 0 && threadID < THREAD_MAX);
321 assert(!pos.is_check());
323 memset(&ei, 0, sizeof(EvalInfo));
325 // Initialize by reading the incrementally updated scores included in the
326 // position object (material + piece square tables)
327 ei.value = pos.value();
329 // Probe the material hash table
330 ei.mi = MaterialTable[threadID]->get_material_info(pos);
331 ei.value += ei.mi->material_value();
333 // If we have a specialized evaluation function for the current material
334 // configuration, call it and return
335 if (ei.mi->specialized_eval_exists())
336 return ei.mi->evaluate(pos);
338 // After get_material_info() call that modifies them
339 ScaleFactor factor[2];
340 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
341 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
343 // Probe the pawn hash table
344 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
345 ei.value += apply_weight(ei.pi->value(), WeightPawnStructureMidgame, WeightPawnStructureEndgame);
347 // Initialize king attack bitboards and king attack zones for both sides
348 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
349 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
350 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
351 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
353 // Initialize pawn attack bitboards for both sides
354 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
355 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
356 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
357 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
359 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
362 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
365 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
366 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
368 // Kings. Kings are evaluated after all other pieces for both sides,
369 // because we need complete attack information for all pieces when computing
370 // the king safety evaluation.
371 evaluate_king<WHITE, HasPopCnt>(pos, ei);
372 evaluate_king<BLACK, HasPopCnt>(pos, ei);
374 // Evaluate tactical threats, we need full attack info
375 evaluate_threats<WHITE>(pos, ei);
376 evaluate_threats<BLACK>(pos, ei);
378 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
379 // because we need to know which side promotes first in positions where
380 // both sides have an unstoppable passed pawn. To be called after all attacks
381 // are computed, included king.
382 if (ei.pi->passed_pawns())
383 evaluate_passed_pawns(pos, ei);
385 Phase phase = pos.game_phase();
387 // Middle-game specific evaluation terms
388 if (phase > PHASE_ENDGAME)
390 // Pawn storms in positions with opposite castling.
391 if ( square_file(pos.king_square(WHITE)) >= FILE_E
392 && square_file(pos.king_square(BLACK)) <= FILE_D)
394 ei.value += Score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
396 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
397 && square_file(pos.king_square(BLACK)) >= FILE_E)
399 ei.value += Score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
401 // Evaluate space for both sides
402 if (ei.mi->space_weight() > 0)
404 evaluate_space<WHITE, HasPopCnt>(pos, ei);
405 evaluate_space<BLACK, HasPopCnt>(pos, ei);
410 ei.value += apply_weight(ei.mobility, WeightMobilityMidgame, WeightMobilityEndgame);
412 // If we don't already have an unusual scale factor, check for opposite
413 // colored bishop endgames, and use a lower scale for those
414 if ( phase < PHASE_MIDGAME
415 && pos.opposite_colored_bishops()
416 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.value.eg() > Value(0))
417 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.value.eg() < Value(0))))
421 // Only the two bishops ?
422 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
423 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
425 // Check for KBP vs KB with only a single pawn that is almost
426 // certainly a draw or at least two pawns.
427 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
428 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
431 // Endgame with opposite-colored bishops, but also other pieces. Still
432 // a bit drawish, but not as drawish as with only the two bishops.
433 sf = ScaleFactor(50);
435 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
437 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
441 // Interpolate between the middle game and the endgame score
442 Color stm = pos.side_to_move();
444 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
446 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
451 /// quick_evaluate() does a very approximate evaluation of the current position.
452 /// It currently considers only material and piece square table scores. Perhaps
453 /// we should add scores from the pawn and material hash tables?
455 Value quick_evaluate(const Position &pos) {
460 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
462 Phase ph = pos.game_phase();
463 Color stm = pos.side_to_move();
465 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
469 /// init_eval() initializes various tables used by the evaluation function
471 void init_eval(int threads) {
473 assert(threads <= THREAD_MAX);
475 for (int i = 0; i < THREAD_MAX; i++)
480 delete MaterialTable[i];
482 MaterialTable[i] = NULL;
486 PawnTable[i] = new PawnInfoTable(PawnTableSize);
487 if (!MaterialTable[i])
488 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
493 /// quit_eval() releases heap-allocated memory at program termination
497 for (int i = 0; i < THREAD_MAX; i++)
500 delete MaterialTable[i];
502 MaterialTable[i] = NULL;
507 /// read_weights() reads evaluation weights from the corresponding UCI parameters
509 void read_weights(Color us) {
511 Color them = opposite_color(us);
513 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
514 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
515 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
516 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
517 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
518 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
519 WeightSpace = weight_option("Space", WeightSpaceInternal);
520 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
521 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
523 // If running in analysis mode, make sure we use symmetrical king safety. We do this
524 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
525 if (get_option_value_bool("UCI_AnalyseMode"))
527 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
528 WeightKingSafety[them] = WeightKingSafety[us];
536 // evaluate_mobility() computes mobility and attacks for every piece
538 template<PieceType Piece, Color Us, bool HasPopCnt>
539 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
541 const Color Them = (Us == WHITE ? BLACK : WHITE);
543 // Update attack info
544 ei.attackedBy[Us][Piece] |= b;
547 if (b & ei.kingZone[Us])
549 ei.kingAttackersCount[Us]++;
550 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
551 Bitboard bb = (b & ei.attackedBy[Them][KING]);
553 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
557 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
558 : count_1s<HasPopCnt>(b & mob_area));
560 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
565 // evaluate_outposts() evaluates bishop and knight outposts squares
567 template<PieceType Piece, Color Us>
568 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
570 const Color Them = (Us == WHITE ? BLACK : WHITE);
572 // Initial bonus based on square
573 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
574 : KnightOutpostBonus[relative_square(Us, s)]);
576 // Increase bonus if supported by pawn, especially if the opponent has
577 // no minor piece which can exchange the outpost piece
578 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
580 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
581 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
582 bonus += bonus + bonus / 2;
586 ei.value += Sign[Us] * Score(bonus, bonus);
590 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
592 template<PieceType Piece, Color Us, bool HasPopCnt>
593 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
600 const Color Them = (Us == WHITE ? BLACK : WHITE);
601 const Square* ptr = pos.piece_list_begin(Us, Piece);
603 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
604 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
606 while ((s = *ptr++) != SQ_NONE)
608 if (Piece == KNIGHT || Piece == QUEEN)
609 b = pos.attacks_from<Piece>(s);
610 else if (Piece == BISHOP)
611 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
612 else if (Piece == ROOK)
613 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
617 // Attacks and mobility
618 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
620 // Decrease score if we are attacked by an enemy pawn. Remaining part
621 // of threat evaluation must be done later when we have full attack info.
622 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
623 ei.value -= Sign[Us] * Score(MidgameThreatedByPawnPenalty[Piece], EndgameThreatedByPawnPenalty[Piece]);
625 // Bishop and knight outposts squares
626 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
627 evaluate_outposts<Piece, Us>(pos, ei, s);
629 // Special patterns: trapped bishops on a7/h7/a2/h2
630 // and trapped bishops on a1/h1/a8/h8 in Chess960.
633 if (bit_is_set(MaskA7H7[Us], s))
634 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
636 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
637 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
640 if (Piece == ROOK || Piece == QUEEN)
642 // Queen or rook on 7th rank
643 if ( relative_rank(Us, s) == RANK_7
644 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
646 ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
650 // Special extra evaluation for rooks
653 // Open and half-open files
655 if (ei.pi->file_is_half_open(Us, f))
657 if (ei.pi->file_is_half_open(Them, f))
658 ei.value += Sign[Us] * Score(RookOpenFileBonus, RookOpenFileBonus);
660 ei.value += Sign[Us] * Score(RookHalfOpenFileBonus, RookHalfOpenFileBonus);
663 // Penalize rooks which are trapped inside a king. Penalize more if
664 // king has lost right to castle.
665 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
668 ksq = pos.king_square(Us);
670 if ( square_file(ksq) >= FILE_E
671 && square_file(s) > square_file(ksq)
672 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
674 // Is there a half-open file between the king and the edge of the board?
675 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
676 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
677 : (TrappedRookPenalty - mob * 16), 0);
679 else if ( square_file(ksq) <= FILE_D
680 && square_file(s) < square_file(ksq)
681 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
683 // Is there a half-open file between the king and the edge of the board?
684 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
685 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
686 : (TrappedRookPenalty - mob * 16), 0);
693 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
694 // and the type of attacked one.
697 void evaluate_threats(const Position& pos, EvalInfo& ei) {
699 const Color Them = (Us == WHITE ? BLACK : WHITE);
704 // Enemy pieces not defended by a pawn and under our attack
705 Bitboard weakEnemies = pos.pieces_of_color(Them)
706 & ~ei.attackedBy[Them][PAWN]
707 & ei.attackedBy[Us][0];
711 // Add bonus according to type of attacked enemy pieces and to the
712 // type of attacking piece, from knights to queens. Kings are not
713 // considered because are already special handled in king evaluation.
714 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
716 b = ei.attackedBy[Us][pt1] & weakEnemies;
718 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
719 if (b & pos.pieces(pt2))
720 bonus += Score(MidgameThreatBonus[pt1][pt2], EndgameThreatBonus[pt1][pt2]);
722 ei.value += Sign[Us] * bonus;
726 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
727 // pieces of a given color.
729 template<Color Us, bool HasPopCnt>
730 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
732 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
733 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
734 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
735 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
737 // Sum up all attacked squares
738 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
739 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
740 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
744 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
746 template<Color Us, bool HasPopCnt>
747 void evaluate_king(const Position& pos, EvalInfo& ei) {
749 const Color Them = (Us == WHITE ? BLACK : WHITE);
750 const Square s = pos.king_square(Us);
754 if (relative_rank(Us, s) <= RANK_4)
756 shelter = ei.pi->get_king_shelter(pos, Us, s);
757 ei.value += Sign[Us] * Score(shelter, 0);
760 // King safety. This is quite complicated, and is almost certainly far
761 // from optimally tuned.
762 if ( pos.piece_count(Them, QUEEN) >= 1
763 && ei.kingAttackersCount[Them] >= 2
764 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
765 && ei.kingAdjacentZoneAttacksCount[Them])
767 // Is it the attackers turn to move?
768 bool sente = (Them == pos.side_to_move());
770 // Find the attacked squares around the king which has no defenders
771 // apart from the king itself
772 Bitboard undefended =
773 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
774 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
775 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
776 & ei.attacked_by(Us, KING);
778 Bitboard occ = pos.occupied_squares(), b, b2;
780 // Initialize the 'attackUnits' variable, which is used later on as an
781 // index to the SafetyTable[] array. The initial value is based on the
782 // number and types of the attacking pieces, the number of attacked and
783 // undefended squares around the king, the square of the king, and the
784 // quality of the pawn shelter.
786 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
787 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
788 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
790 // Analyse safe queen contact checks
791 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
794 Bitboard attackedByOthers =
795 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
796 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
798 b &= attackedByOthers;
801 // The bitboard b now contains the squares available for safe queen
803 int count = count_1s_max_15<HasPopCnt>(b);
804 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
806 // Is there a mate threat?
807 if (QueenContactMates && !pos.is_check())
809 Bitboard escapeSquares =
810 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
814 Square from, to = pop_1st_bit(&b);
815 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
817 // We have a mate, unless the queen is pinned or there
818 // is an X-ray attack through the queen.
819 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
821 from = pos.piece_list(Them, QUEEN, i);
822 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
823 && !bit_is_set(pos.pinned_pieces(Them), from)
824 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
825 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
827 ei.mateThreat[Them] = make_move(from, to);
835 // Analyse safe distance checks
836 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
838 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
841 b2 = b & ei.attacked_by(Them, QUEEN);
843 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
846 b2 = b & ei.attacked_by(Them, ROOK);
848 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
850 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
852 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
855 b2 = b & ei.attacked_by(Them, QUEEN);
857 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
860 b2 = b & ei.attacked_by(Them, BISHOP);
862 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
864 if (KnightCheckBonus > 0)
866 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
869 b2 = b & ei.attacked_by(Them, KNIGHT);
871 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
874 // Analyse discovered checks (only for non-pawns right now, consider
875 // adding pawns later).
876 if (DiscoveredCheckBonus)
878 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
880 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
883 // Has a mate threat been found? We don't do anything here if the
884 // side with the mating move is the side to move, because in that
885 // case the mating side will get a huge bonus at the end of the main
886 // evaluation function instead.
887 if (ei.mateThreat[Them] != MOVE_NONE)
888 attackUnits += MateThreatBonus;
890 // Ensure that attackUnits is between 0 and 99, in order to avoid array
891 // out of bounds errors:
895 if (attackUnits >= 100)
898 // Finally, extract the king safety score from the SafetyTable[] array.
899 // Add the score to the evaluation, and also to ei.futilityMargin. The
900 // reason for adding the king safety score to the futility margin is
901 // that the king safety scores can sometimes be very big, and that
902 // capturing a single attacking piece can therefore result in a score
903 // change far bigger than the value of the captured piece.
904 Score v = apply_weight(Score(SafetyTable[attackUnits], 0), WeightKingSafety[Us], 0);
906 ei.value -= Sign[Us] * v;
908 if (Us == pos.side_to_move())
909 ei.futilityMargin += v.mg();
914 // evaluate_passed_pawns() evaluates the passed pawns of the given color
917 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
919 const Color Them = (Us == WHITE ? BLACK : WHITE);
922 Square ourKingSq = pos.king_square(Us);
923 Square theirKingSq = pos.king_square(Them);
924 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
928 Square s = pop_1st_bit(&b);
930 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
931 assert(pos.pawn_is_passed(Us, s));
933 int r = int(relative_rank(Us, s) - RANK_2);
934 int tr = Max(0, r * (r - 1));
936 // Base bonus based on rank
937 Value mbonus = Value(20 * tr);
938 Value ebonus = Value(10 + r * r * 10);
940 // Adjust bonus based on king proximity
943 Square blockSq = s + pawn_push(Us);
945 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
946 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
947 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
949 // If the pawn is free to advance, increase bonus
950 if (pos.square_is_empty(blockSq))
952 // There are no enemy pawns in the pawn's path
953 b2 = squares_in_front_of(Us, s);
955 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
957 // Squares attacked by us
958 b4 = b2 & ei.attacked_by(Us);
960 // Squares attacked or occupied by enemy pieces
961 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
963 // If there is an enemy rook or queen attacking the pawn from behind,
964 // add all X-ray attacks by the rook or queen.
965 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
966 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
969 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
970 if (b3 == EmptyBoardBB)
971 // No enemy attacks or pieces, huge bonus!
972 // Even bigger if we protect the pawn's path
973 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
975 // OK, there are enemy attacks or pieces (but not pawns). Are those
976 // squares which are attacked by the enemy also attacked by us ?
977 // If yes, big bonus (but smaller than when there are no enemy attacks),
978 // if no, somewhat smaller bonus.
979 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
981 // At last, add a small bonus when there are no *friendly* pieces
982 // in the pawn's path.
983 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
988 // If the pawn is supported by a friendly pawn, increase bonus
989 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
991 ebonus += Value(r * 20);
992 else if (pos.attacks_from<PAWN>(s, Them) & b2)
993 ebonus += Value(r * 12);
995 // If the other side has only a king, check whether the pawn is
997 if (pos.non_pawn_material(Them) == Value(0))
1002 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1003 d = square_distance(s, qsq)
1004 - square_distance(theirKingSq, qsq)
1005 + (Us != pos.side_to_move());
1009 int mtg = RANK_8 - relative_rank(Us, s);
1010 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1011 mtg += blockerCount;
1013 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1015 movesToGo[Us] = mtg;
1021 // Rook pawns are a special case: They are sometimes worse, and
1022 // sometimes better than other passed pawns. It is difficult to find
1023 // good rules for determining whether they are good or bad. For now,
1024 // we try the following: Increase the value for rook pawns if the
1025 // other side has no pieces apart from a knight, and decrease the
1026 // value if the other side has a rook or queen.
1027 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1029 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1030 && pos.piece_count(Them, KNIGHT) <= 1)
1031 ebonus += ebonus / 4;
1032 else if (pos.pieces(ROOK, QUEEN, Them))
1033 ebonus -= ebonus / 4;
1036 // Add the scores for this pawn to the middle game and endgame eval.
1037 ei.value += Sign[Us] * apply_weight(Score(mbonus, ebonus), WeightPassedPawnsMidgame, WeightPassedPawnsEndgame);
1043 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1045 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1047 int movesToGo[2] = {0, 0};
1048 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1050 // Evaluate pawns for each color
1051 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1052 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1054 // Neither side has an unstoppable passed pawn?
1055 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1058 // Does only one side have an unstoppable passed pawn?
1059 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1061 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1062 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1065 { // Both sides have unstoppable pawns! Try to find out who queens
1066 // first. We begin by transforming 'movesToGo' to the number of
1067 // plies until the pawn queens for both sides.
1068 movesToGo[WHITE] *= 2;
1069 movesToGo[BLACK] *= 2;
1070 movesToGo[pos.side_to_move()]--;
1072 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1073 Color loserSide = opposite_color(winnerSide);
1075 // If one side queens at least three plies before the other, that side wins
1076 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1077 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1079 // If one side queens one ply before the other and checks the king or attacks
1080 // the undefended opponent's queening square, that side wins. To avoid cases
1081 // where the opponent's king could move somewhere before first pawn queens we
1082 // consider only free paths to queen for both pawns.
1083 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1084 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1086 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1088 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1089 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1091 Bitboard b = pos.occupied_squares();
1092 clear_bit(&b, pawnToGo[winnerSide]);
1093 clear_bit(&b, pawnToGo[loserSide]);
1094 b = queen_attacks_bb(winnerQSq, b);
1096 if ( (b & pos.pieces(KING, loserSide))
1097 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1098 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1104 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1105 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1108 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1110 assert(square_is_ok(s));
1111 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1113 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1114 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1116 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1117 && pos.see(s, b6) < 0
1118 && pos.see(s, b8) < 0)
1120 ei.value -= Sign[us] * Score(TrappedBishopA7H7Penalty, TrappedBishopA7H7Penalty);
1125 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1126 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1127 // black), and assigns a penalty if it is. This pattern can obviously
1128 // only occur in Chess960 games.
1130 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1132 Piece pawn = piece_of_color_and_type(us, PAWN);
1136 assert(square_is_ok(s));
1137 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1139 if (square_file(s) == FILE_A)
1141 b2 = relative_square(us, SQ_B2);
1142 b3 = relative_square(us, SQ_B3);
1143 c3 = relative_square(us, SQ_C3);
1147 b2 = relative_square(us, SQ_G2);
1148 b3 = relative_square(us, SQ_G3);
1149 c3 = relative_square(us, SQ_F3);
1152 if (pos.piece_on(b2) == pawn)
1156 if (!pos.square_is_empty(b3))
1157 penalty = 2*TrappedBishopA1H1Penalty;
1158 else if (pos.piece_on(c3) == pawn)
1159 penalty = TrappedBishopA1H1Penalty;
1161 penalty = TrappedBishopA1H1Penalty / 2;
1163 ei.value -= Sign[us] * Score(penalty, penalty);
1168 // evaluate_space() computes the space evaluation for a given side. The
1169 // space evaluation is a simple bonus based on the number of safe squares
1170 // available for minor pieces on the central four files on ranks 2--4. Safe
1171 // squares one, two or three squares behind a friendly pawn are counted
1172 // twice. Finally, the space bonus is scaled by a weight taken from the
1173 // material hash table.
1174 template<Color Us, bool HasPopCnt>
1175 void evaluate_space(const Position& pos, EvalInfo& ei) {
1177 const Color Them = (Us == WHITE ? BLACK : WHITE);
1179 // Find the safe squares for our pieces inside the area defined by
1180 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1181 // pawn, or if it is undefended and attacked by an enemy piece.
1183 Bitboard safeSquares = SpaceMask[Us]
1184 & ~pos.pieces(PAWN, Us)
1185 & ~ei.attacked_by(Them, PAWN)
1186 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1188 // Find all squares which are at most three squares behind some friendly
1190 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1191 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1192 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1194 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1195 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1197 ei.value += Sign[Us] * apply_weight(Score(space * ei.mi->space_weight(), 0), WeightSpace, 0);
1201 // apply_weight() applies an evaluation weight to a value
1203 inline Score apply_weight(Score v, int wmg, int weg) {
1204 return Score(v.mg() * wmg, v.eg() * weg) / 0x100;
1208 // scale_by_game_phase() interpolates between a middle game and an endgame
1209 // score, based on game phase. It also scales the return value by a
1210 // ScaleFactor array.
1212 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1214 assert(v.mg() > -VALUE_INFINITE && v.mg() < VALUE_INFINITE);
1215 assert(v.eg() > -VALUE_INFINITE && v.eg() < VALUE_INFINITE);
1216 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1218 Value ev = apply_scale_factor(v.eg(), sf[(v.eg() > Value(0) ? WHITE : BLACK)]);
1220 Value result = Value(int((v.mg() * ph + ev * (128 - ph)) / 128));
1221 return Value(int(result) & ~(GrainSize - 1));
1225 // weight_option() computes the value of an evaluation weight, by combining
1226 // an UCI-configurable weight with an internal weight.
1228 int weight_option(const std::string& opt, int internalWeight) {
1230 int uciWeight = get_option_value_int(opt);
1231 uciWeight = (uciWeight * 0x100) / 100;
1232 return (uciWeight * internalWeight) / 0x100;
1236 // init_safety() initizes the king safety evaluation, based on UCI
1237 // parameters. It is called from read_weights().
1239 void init_safety() {
1241 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1242 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1243 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1244 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1245 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1246 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1247 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1249 int maxSlope = get_option_value_int("King Safety Max Slope");
1250 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1251 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1252 double b = get_option_value_int("King Safety X Intercept");
1253 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1254 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1256 for (int i = 0; i < 100; i++)
1259 SafetyTable[i] = Value(0);
1261 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1263 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1266 for (int i = 0; i < 100; i++)
1268 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1269 for (int j = i + 1; j < 100; j++)
1270 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1272 if (SafetyTable[i] > Value(peak))
1273 SafetyTable[i] = Value(peak);
1278 std::ostream& operator<<(std::ostream &os, Score s) {
1280 return os << "(" << s.mg() << ", " << s.eg() << ")";