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 Value MidgameRookOn7thBonus = Value(47);
149 const Value EndgameRookOn7thBonus = Value(98);
150 const Value MidgameQueenOn7thBonus = Value(27);
151 const Value EndgameQueenOn7thBonus = Value(54);
153 // Rooks on open files (modified by Joona Kiiski)
154 const Value RookOpenFileBonus = Value(43);
155 const Value RookHalfOpenFileBonus = Value(19);
157 // Penalty for rooks trapped inside a friendly king which has lost the
159 const Value TrappedRookPenalty = Value(180);
161 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
163 const Value TrappedBishopA7H7Penalty = Value(300);
165 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
166 const Bitboard MaskA7H7[2] = {
167 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
168 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
171 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
172 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
173 // happen in Chess960 games.
174 const Value TrappedBishopA1H1Penalty = Value(100);
176 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
177 const Bitboard MaskA1H1[2] = {
178 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
179 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
182 // The SpaceMask[color] contains the area of the board which is considered
183 // by the space evaluation. In the middle game, each side is given a bonus
184 // based on how many squares inside this area are safe and available for
185 // friendly minor pieces.
186 const Bitboard SpaceMask[2] = {
187 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
188 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
189 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
190 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
191 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
192 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
195 /// King safety constants and variables. The king safety scores are taken
196 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
197 /// the strength of the attack are added up into an integer, which is used
198 /// as an index to SafetyTable[].
200 // Attack weights for each piece type and table indexed on piece type
201 const int QueenAttackWeight = 5;
202 const int RookAttackWeight = 3;
203 const int BishopAttackWeight = 2;
204 const int KnightAttackWeight = 2;
206 const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
208 // Bonuses for safe checks, initialized from UCI options
209 int QueenContactCheckBonus, DiscoveredCheckBonus;
210 int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
212 // Scan for queen contact mates?
213 const bool QueenContactMates = true;
215 // Bonus for having a mate threat, initialized from UCI options
218 // ThreatBonus[][] contains bonus according to which piece type
219 // attacks which one.
220 const Value MidgameThreatBonus[8][8] = {
221 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
222 { V(0),V(18), V(0),V(37), V(55), V(55), V(0), V(0) }, // KNIGHT attacks
223 { V(0),V(18),V(37), V(0), V(55), V(55), V(0), V(0) }, // BISHOP attacks
224 { V(0), V(9),V(27),V(27), V(0), V(37), V(0), V(0) }, // ROOK attacks
225 { V(0),V(27),V(27),V(27), V(27), V(0), V(0), V(0) }, // QUEEN attacks
226 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
227 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
228 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) } // not used
231 const Value EndgameThreatBonus[8][8] = {
232 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
233 { V(0),V(37), V(0),V(47), V(97), V(97), V(0), V(0) }, // KNIGHT attacks
234 { V(0),V(37),V(47), V(0), V(97), V(97), V(0), V(0) }, // BISHOP attacks
235 { V(0),V(27),V(47),V(47), V(0), V(47), V(0), V(0) }, // ROOK attacks
236 { V(0),V(37),V(37),V(37), V(37), V(0), V(0), V(0) }, // QUEEN attacks
237 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
238 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }, // not used
239 { V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) } // not used
242 // ThreatedByPawnPenalty[] contains a penalty according to which piece
243 // type is attacked by an enemy pawn.
244 const Value MidgameThreatedByPawnPenalty[8] = {
245 V(0), V(0), V(56), V(56), V(76), V(86), V(0), V(0)
248 const Value EndgameThreatedByPawnPenalty[8] = {
249 V(0), V(0), V(70), V(70), V(99), V(118), V(0), V(0)
252 // InitKingDanger[] contains bonuses based on the position of the defending
254 const int InitKingDanger[64] = {
255 2, 0, 2, 5, 5, 2, 0, 2,
256 2, 2, 4, 8, 8, 4, 2, 2,
257 7, 10, 12, 12, 12, 12, 10, 7,
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,
261 15, 15, 15, 15, 15, 15, 15, 15,
262 15, 15, 15, 15, 15, 15, 15, 15
265 // SafetyTable[] contains the actual king safety scores. It is initialized
267 Value SafetyTable[100];
269 // Pawn and material hash tables, indexed by the current thread id
270 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
271 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
273 // Sizes of pawn and material hash tables
274 const int PawnTableSize = 16384;
275 const int MaterialTableSize = 1024;
277 // Function prototypes
278 template<bool HasPopCnt>
279 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
281 template<Color Us, bool HasPopCnt>
282 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
284 template<Color Us, bool HasPopCnt>
285 void evaluate_king(const Position& pos, EvalInfo& ei);
288 void evaluate_threats(const Position& pos, EvalInfo& ei);
290 template<Color Us, bool HasPopCnt>
291 void evaluate_space(const Position& pos, EvalInfo& ei);
293 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
294 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
295 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
296 inline Score apply_weight(Score v, int wmg, int weg);
297 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
298 int weight_option(const std::string& opt, int weight);
307 /// evaluate() is the main evaluation function. It always computes two
308 /// values, an endgame score and a middle game score, and interpolates
309 /// between them based on the remaining material.
310 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
312 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
313 : do_evaluate<false>(pos, ei, threadID);
318 template<bool HasPopCnt>
319 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
322 assert(threadID >= 0 && threadID < THREAD_MAX);
323 assert(!pos.is_check());
325 memset(&ei, 0, sizeof(EvalInfo));
327 // Initialize by reading the incrementally updated scores included in the
328 // position object (material + piece square tables)
329 ei.value = pos.value();
331 // Probe the material hash table
332 ei.mi = MaterialTable[threadID]->get_material_info(pos);
333 ei.value += ei.mi->material_value();
335 // If we have a specialized evaluation function for the current material
336 // configuration, call it and return
337 if (ei.mi->specialized_eval_exists())
338 return ei.mi->evaluate(pos);
340 // After get_material_info() call that modifies them
341 ScaleFactor factor[2];
342 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
343 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
345 // Probe the pawn hash table
346 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
347 ei.value += apply_weight(ei.pi->value(), WeightPawnStructureMidgame, WeightPawnStructureEndgame);
349 // Initialize king attack bitboards and king attack zones for both sides
350 ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.king_square(WHITE));
351 ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.king_square(BLACK));
352 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
353 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
355 // Initialize pawn attack bitboards for both sides
356 ei.attackedBy[WHITE][PAWN] = ei.pi->pawn_attacks(WHITE);
357 ei.attackedBy[BLACK][PAWN] = ei.pi->pawn_attacks(BLACK);
358 Bitboard b1 = ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING];
359 Bitboard b2 = ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING];
361 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(b1)/2;
364 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(b2)/2;
367 evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
368 evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
370 // Kings. Kings are evaluated after all other pieces for both sides,
371 // because we need complete attack information for all pieces when computing
372 // the king safety evaluation.
373 evaluate_king<WHITE, HasPopCnt>(pos, ei);
374 evaluate_king<BLACK, HasPopCnt>(pos, ei);
376 // Evaluate tactical threats, we need full attack info
377 evaluate_threats<WHITE>(pos, ei);
378 evaluate_threats<BLACK>(pos, ei);
380 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
381 // because we need to know which side promotes first in positions where
382 // both sides have an unstoppable passed pawn. To be called after all attacks
383 // are computed, included king.
384 if (ei.pi->passed_pawns())
385 evaluate_passed_pawns(pos, ei);
387 Phase phase = pos.game_phase();
389 // Middle-game specific evaluation terms
390 if (phase > PHASE_ENDGAME)
392 // Pawn storms in positions with opposite castling.
393 if ( square_file(pos.king_square(WHITE)) >= FILE_E
394 && square_file(pos.king_square(BLACK)) <= FILE_D)
396 ei.value += Score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
398 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
399 && square_file(pos.king_square(BLACK)) >= FILE_E)
401 ei.value += Score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
403 // Evaluate space for both sides
404 if (ei.mi->space_weight() > 0)
406 evaluate_space<WHITE, HasPopCnt>(pos, ei);
407 evaluate_space<BLACK, HasPopCnt>(pos, ei);
412 ei.value += apply_weight(ei.mobility, WeightMobilityMidgame, WeightMobilityEndgame);
414 // If we don't already have an unusual scale factor, check for opposite
415 // colored bishop endgames, and use a lower scale for those
416 if ( phase < PHASE_MIDGAME
417 && pos.opposite_colored_bishops()
418 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.value.eg() > Value(0))
419 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.value.eg() < Value(0))))
423 // Only the two bishops ?
424 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
425 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
427 // Check for KBP vs KB with only a single pawn that is almost
428 // certainly a draw or at least two pawns.
429 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
430 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
433 // Endgame with opposite-colored bishops, but also other pieces. Still
434 // a bit drawish, but not as drawish as with only the two bishops.
435 sf = ScaleFactor(50);
437 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
439 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
443 // Interpolate between the middle game and the endgame score
444 Color stm = pos.side_to_move();
446 Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
448 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
453 /// quick_evaluate() does a very approximate evaluation of the current position.
454 /// It currently considers only material and piece square table scores. Perhaps
455 /// we should add scores from the pawn and material hash tables?
457 Value quick_evaluate(const Position &pos) {
462 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
464 Phase ph = pos.game_phase();
465 Color stm = pos.side_to_move();
467 return Sign[stm] * scale_by_game_phase(pos.value(), ph, sf);
471 /// init_eval() initializes various tables used by the evaluation function
473 void init_eval(int threads) {
475 assert(threads <= THREAD_MAX);
477 for (int i = 0; i < THREAD_MAX; i++)
482 delete MaterialTable[i];
484 MaterialTable[i] = NULL;
488 PawnTable[i] = new PawnInfoTable(PawnTableSize);
489 if (!MaterialTable[i])
490 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
495 /// quit_eval() releases heap-allocated memory at program termination
499 for (int i = 0; i < THREAD_MAX; i++)
502 delete MaterialTable[i];
504 MaterialTable[i] = NULL;
509 /// read_weights() reads evaluation weights from the corresponding UCI parameters
511 void read_weights(Color us) {
513 Color them = opposite_color(us);
515 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
516 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
517 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
518 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
519 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
520 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
521 WeightSpace = weight_option("Space", WeightSpaceInternal);
522 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
523 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
525 // If running in analysis mode, make sure we use symmetrical king safety. We do this
526 // by replacing both WeightKingSafety[us] and WeightKingSafety[them] by their average.
527 if (get_option_value_bool("UCI_AnalyseMode"))
529 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
530 WeightKingSafety[them] = WeightKingSafety[us];
538 // evaluate_mobility() computes mobility and attacks for every piece
540 template<PieceType Piece, Color Us, bool HasPopCnt>
541 int evaluate_mobility(Bitboard b, Bitboard mob_area, EvalInfo& ei) {
543 const Color Them = (Us == WHITE ? BLACK : WHITE);
545 // Update attack info
546 ei.attackedBy[Us][Piece] |= b;
549 if (b & ei.kingZone[Us])
551 ei.kingAttackersCount[Us]++;
552 ei.kingAttackersWeight[Us] += AttackWeight[Piece];
553 Bitboard bb = (b & ei.attackedBy[Them][KING]);
555 ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
559 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mob_area)
560 : count_1s<HasPopCnt>(b & mob_area));
562 ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
567 // evaluate_outposts() evaluates bishop and knight outposts squares
569 template<PieceType Piece, Color Us>
570 void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
572 const Color Them = (Us == WHITE ? BLACK : WHITE);
574 // Initial bonus based on square
575 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(Us, s)]
576 : KnightOutpostBonus[relative_square(Us, s)]);
578 // Increase bonus if supported by pawn, especially if the opponent has
579 // no minor piece which can exchange the outpost piece
580 if (bonus && (pos.attacks_from<PAWN>(s, Them) & pos.pieces(PAWN, Us)))
582 if ( pos.pieces(KNIGHT, Them) == EmptyBoardBB
583 && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
584 bonus += bonus + bonus / 2;
588 ei.value += Sign[Us] * Score(bonus, bonus);
592 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
594 template<PieceType Piece, Color Us, bool HasPopCnt>
595 void evaluate_pieces(const Position& pos, EvalInfo& ei) {
602 const Color Them = (Us == WHITE ? BLACK : WHITE);
603 const Square* ptr = pos.piece_list_begin(Us, Piece);
605 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
606 const Bitboard mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
608 while ((s = *ptr++) != SQ_NONE)
610 if (Piece == KNIGHT || Piece == QUEEN)
611 b = pos.attacks_from<Piece>(s);
612 else if (Piece == BISHOP)
613 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
614 else if (Piece == ROOK)
615 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
619 // Attacks and mobility
620 mob = evaluate_mobility<Piece, Us, HasPopCnt>(b, mob_area, ei);
622 // Decrease score if we are attacked by an enemy pawn. Remaining part
623 // of threat evaluation must be done later when we have full attack info.
624 if (bit_is_set(ei.attackedBy[Them][PAWN], s))
625 ei.value -= Sign[Us] * Score(MidgameThreatedByPawnPenalty[Piece], EndgameThreatedByPawnPenalty[Piece]);
627 // Bishop and knight outposts squares
628 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
629 evaluate_outposts<Piece, Us>(pos, ei, s);
631 // Special patterns: trapped bishops on a7/h7/a2/h2
632 // and trapped bishops on a1/h1/a8/h8 in Chess960.
635 if (bit_is_set(MaskA7H7[Us], s))
636 evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
638 if (Chess960 && bit_is_set(MaskA1H1[Us], s))
639 evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
642 if (Piece == ROOK || Piece == QUEEN)
644 // Queen or rook on 7th rank
645 if ( relative_rank(Us, s) == RANK_7
646 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
648 ei.value += Sign[Us] * (Piece == ROOK ? Score(MidgameRookOn7thBonus, EndgameRookOn7thBonus)
649 : Score(MidgameQueenOn7thBonus, EndgameQueenOn7thBonus));
653 // Special extra evaluation for rooks
656 // Open and half-open files
658 if (ei.pi->file_is_half_open(Us, f))
660 if (ei.pi->file_is_half_open(Them, f))
661 ei.value += Sign[Us] * Score(RookOpenFileBonus, RookOpenFileBonus);
663 ei.value += Sign[Us] * Score(RookHalfOpenFileBonus, RookHalfOpenFileBonus);
666 // Penalize rooks which are trapped inside a king. Penalize more if
667 // king has lost right to castle.
668 if (mob > 6 || ei.pi->file_is_half_open(Us, f))
671 ksq = pos.king_square(Us);
673 if ( square_file(ksq) >= FILE_E
674 && square_file(s) > square_file(ksq)
675 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
677 // Is there a half-open file between the king and the edge of the board?
678 if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
679 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
680 : (TrappedRookPenalty - mob * 16), 0);
682 else if ( square_file(ksq) <= FILE_D
683 && square_file(s) < square_file(ksq)
684 && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
686 // Is there a half-open file between the king and the edge of the board?
687 if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
688 ei.value -= Sign[Us] * Score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
689 : (TrappedRookPenalty - mob * 16), 0);
696 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
697 // and the type of attacked one.
700 void evaluate_threats(const Position& pos, EvalInfo& ei) {
702 const Color Them = (Us == WHITE ? BLACK : WHITE);
707 // Enemy pieces not defended by a pawn and under our attack
708 Bitboard weakEnemies = pos.pieces_of_color(Them)
709 & ~ei.attackedBy[Them][PAWN]
710 & ei.attackedBy[Us][0];
714 // Add bonus according to type of attacked enemy pieces and to the
715 // type of attacking piece, from knights to queens. Kings are not
716 // considered because are already special handled in king evaluation.
717 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
719 b = ei.attackedBy[Us][pt1] & weakEnemies;
721 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
722 if (b & pos.pieces(pt2))
723 bonus += Score(MidgameThreatBonus[pt1][pt2], EndgameThreatBonus[pt1][pt2]);
725 ei.value += Sign[Us] * bonus;
729 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
730 // pieces of a given color.
732 template<Color Us, bool HasPopCnt>
733 void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
735 evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei);
736 evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei);
737 evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei);
738 evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei);
740 // Sum up all attacked squares
741 ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
742 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
743 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
747 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
749 template<Color Us, bool HasPopCnt>
750 void evaluate_king(const Position& pos, EvalInfo& ei) {
752 const Color Them = (Us == WHITE ? BLACK : WHITE);
753 const Square s = pos.king_square(Us);
757 if (relative_rank(Us, s) <= RANK_4)
759 shelter = ei.pi->get_king_shelter(pos, Us, s);
760 ei.value += Sign[Us] * Score(shelter, 0);
763 // King safety. This is quite complicated, and is almost certainly far
764 // from optimally tuned.
765 if ( pos.piece_count(Them, QUEEN) >= 1
766 && ei.kingAttackersCount[Them] >= 2
767 && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
768 && ei.kingAdjacentZoneAttacksCount[Them])
770 // Is it the attackers turn to move?
771 bool sente = (Them == pos.side_to_move());
773 // Find the attacked squares around the king which has no defenders
774 // apart from the king itself
775 Bitboard undefended =
776 ei.attacked_by(Them) & ~ei.attacked_by(Us, PAWN)
777 & ~ei.attacked_by(Us, KNIGHT) & ~ei.attacked_by(Us, BISHOP)
778 & ~ei.attacked_by(Us, ROOK) & ~ei.attacked_by(Us, QUEEN)
779 & ei.attacked_by(Us, KING);
781 Bitboard occ = pos.occupied_squares(), b, b2;
783 // Initialize the 'attackUnits' variable, which is used later on as an
784 // index to the SafetyTable[] array. The initial value is based on the
785 // number and types of the attacking pieces, the number of attacked and
786 // undefended squares around the king, the square of the king, and the
787 // quality of the pawn shelter.
789 Min((ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2, 25)
790 + (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
791 + InitKingDanger[relative_square(Us, s)] - (shelter >> 5);
793 // Analyse safe queen contact checks
794 b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
797 Bitboard attackedByOthers =
798 ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
799 | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
801 b &= attackedByOthers;
804 // The bitboard b now contains the squares available for safe queen
806 int count = count_1s_max_15<HasPopCnt>(b);
807 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
809 // Is there a mate threat?
810 if (QueenContactMates && !pos.is_check())
812 Bitboard escapeSquares =
813 pos.attacks_from<KING>(s) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
817 Square from, to = pop_1st_bit(&b);
818 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
820 // We have a mate, unless the queen is pinned or there
821 // is an X-ray attack through the queen.
822 for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
824 from = pos.piece_list(Them, QUEEN, i);
825 if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
826 && !bit_is_set(pos.pinned_pieces(Them), from)
827 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
828 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
830 ei.mateThreat[Them] = make_move(from, to);
838 // Analyse safe distance checks
839 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
841 b = pos.attacks_from<ROOK>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
844 b2 = b & ei.attacked_by(Them, QUEEN);
846 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
849 b2 = b & ei.attacked_by(Them, ROOK);
851 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
853 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
855 b = pos.attacks_from<BISHOP>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
858 b2 = b & ei.attacked_by(Them, QUEEN);
860 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
863 b2 = b & ei.attacked_by(Them, BISHOP);
865 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
867 if (KnightCheckBonus > 0)
869 b = pos.attacks_from<KNIGHT>(s) & ~pos.pieces_of_color(Them) & ~ei.attacked_by(Us);
872 b2 = b & ei.attacked_by(Them, KNIGHT);
874 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
877 // Analyse discovered checks (only for non-pawns right now, consider
878 // adding pawns later).
879 if (DiscoveredCheckBonus)
881 b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
883 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
886 // Has a mate threat been found? We don't do anything here if the
887 // side with the mating move is the side to move, because in that
888 // case the mating side will get a huge bonus at the end of the main
889 // evaluation function instead.
890 if (ei.mateThreat[Them] != MOVE_NONE)
891 attackUnits += MateThreatBonus;
893 // Ensure that attackUnits is between 0 and 99, in order to avoid array
894 // out of bounds errors:
898 if (attackUnits >= 100)
901 // Finally, extract the king safety score from the SafetyTable[] array.
902 // Add the score to the evaluation, and also to ei.futilityMargin. The
903 // reason for adding the king safety score to the futility margin is
904 // that the king safety scores can sometimes be very big, and that
905 // capturing a single attacking piece can therefore result in a score
906 // change far bigger than the value of the captured piece.
907 Score v = apply_weight(Score(SafetyTable[attackUnits], 0), WeightKingSafety[Us], 0);
909 ei.value -= Sign[Us] * v;
911 if (Us == pos.side_to_move())
912 ei.futilityMargin += v.mg();
917 // evaluate_passed_pawns() evaluates the passed pawns of the given color
920 void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
922 const Color Them = (Us == WHITE ? BLACK : WHITE);
925 Square ourKingSq = pos.king_square(Us);
926 Square theirKingSq = pos.king_square(Them);
927 Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
931 Square s = pop_1st_bit(&b);
933 assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
934 assert(pos.pawn_is_passed(Us, s));
936 int r = int(relative_rank(Us, s) - RANK_2);
937 int tr = Max(0, r * (r - 1));
939 // Base bonus based on rank
940 Value mbonus = Value(20 * tr);
941 Value ebonus = Value(10 + r * r * 10);
943 // Adjust bonus based on king proximity
946 Square blockSq = s + pawn_push(Us);
948 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
949 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
950 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
952 // If the pawn is free to advance, increase bonus
953 if (pos.square_is_empty(blockSq))
955 // There are no enemy pawns in the pawn's path
956 b2 = squares_in_front_of(Us, s);
958 assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
960 // Squares attacked by us
961 b4 = b2 & ei.attacked_by(Us);
963 // Squares attacked or occupied by enemy pieces
964 b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
966 // If there is an enemy rook or queen attacking the pawn from behind,
967 // add all X-ray attacks by the rook or queen.
968 if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
969 && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
972 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
973 if (b3 == EmptyBoardBB)
974 // No enemy attacks or pieces, huge bonus!
975 // Even bigger if we protect the pawn's path
976 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
978 // OK, there are enemy attacks or pieces (but not pawns). Are those
979 // squares which are attacked by the enemy also attacked by us ?
980 // If yes, big bonus (but smaller than when there are no enemy attacks),
981 // if no, somewhat smaller bonus.
982 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
984 // At last, add a small bonus when there are no *friendly* pieces
985 // in the pawn's path.
986 if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
991 // If the pawn is supported by a friendly pawn, increase bonus
992 b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
994 ebonus += Value(r * 20);
995 else if (pos.attacks_from<PAWN>(s, Them) & b2)
996 ebonus += Value(r * 12);
998 // If the other side has only a king, check whether the pawn is
1000 if (pos.non_pawn_material(Them) == Value(0))
1005 qsq = relative_square(Us, make_square(square_file(s), RANK_8));
1006 d = square_distance(s, qsq)
1007 - square_distance(theirKingSq, qsq)
1008 + (Us != pos.side_to_move());
1012 int mtg = RANK_8 - relative_rank(Us, s);
1013 int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
1014 mtg += blockerCount;
1016 if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
1018 movesToGo[Us] = mtg;
1024 // Rook pawns are a special case: They are sometimes worse, and
1025 // sometimes better than other passed pawns. It is difficult to find
1026 // good rules for determining whether they are good or bad. For now,
1027 // we try the following: Increase the value for rook pawns if the
1028 // other side has no pieces apart from a knight, and decrease the
1029 // value if the other side has a rook or queen.
1030 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1032 if ( pos.non_pawn_material(Them) <= KnightValueMidgame
1033 && pos.piece_count(Them, KNIGHT) <= 1)
1034 ebonus += ebonus / 4;
1035 else if (pos.pieces(ROOK, QUEEN, Them))
1036 ebonus -= ebonus / 4;
1039 // Add the scores for this pawn to the middle game and endgame eval.
1040 ei.value += Sign[Us] * apply_weight(Score(mbonus, ebonus), WeightPassedPawnsMidgame, WeightPassedPawnsEndgame);
1046 // evaluate_passed_pawns() evaluates the passed pawns for both sides
1048 void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
1050 int movesToGo[2] = {0, 0};
1051 Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
1053 // Evaluate pawns for each color
1054 evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
1055 evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
1057 // Neither side has an unstoppable passed pawn?
1058 if (!(movesToGo[WHITE] | movesToGo[BLACK]))
1061 // Does only one side have an unstoppable passed pawn?
1062 if (!movesToGo[WHITE] || !movesToGo[BLACK])
1064 Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
1065 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide])));
1068 { // Both sides have unstoppable pawns! Try to find out who queens
1069 // first. We begin by transforming 'movesToGo' to the number of
1070 // plies until the pawn queens for both sides.
1071 movesToGo[WHITE] *= 2;
1072 movesToGo[BLACK] *= 2;
1073 movesToGo[pos.side_to_move()]--;
1075 Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
1076 Color loserSide = opposite_color(winnerSide);
1078 // If one side queens at least three plies before the other, that side wins
1079 if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
1080 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1082 // If one side queens one ply before the other and checks the king or attacks
1083 // the undefended opponent's queening square, that side wins. To avoid cases
1084 // where the opponent's king could move somewhere before first pawn queens we
1085 // consider only free paths to queen for both pawns.
1086 else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
1087 && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
1089 assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
1091 Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
1092 Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
1094 Bitboard b = pos.occupied_squares();
1095 clear_bit(&b, pawnToGo[winnerSide]);
1096 clear_bit(&b, pawnToGo[loserSide]);
1097 b = queen_attacks_bb(winnerQSq, b);
1099 if ( (b & pos.pieces(KING, loserSide))
1100 ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
1101 ei.value += Score(0, Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2))));
1107 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1108 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1111 void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
1113 assert(square_is_ok(s));
1114 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1116 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1117 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1119 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1120 && pos.see(s, b6) < 0
1121 && pos.see(s, b8) < 0)
1123 ei.value -= Sign[us] * Score(TrappedBishopA7H7Penalty, TrappedBishopA7H7Penalty);
1128 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1129 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1130 // black), and assigns a penalty if it is. This pattern can obviously
1131 // only occur in Chess960 games.
1133 void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
1135 Piece pawn = piece_of_color_and_type(us, PAWN);
1139 assert(square_is_ok(s));
1140 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1142 if (square_file(s) == FILE_A)
1144 b2 = relative_square(us, SQ_B2);
1145 b3 = relative_square(us, SQ_B3);
1146 c3 = relative_square(us, SQ_C3);
1150 b2 = relative_square(us, SQ_G2);
1151 b3 = relative_square(us, SQ_G3);
1152 c3 = relative_square(us, SQ_F3);
1155 if (pos.piece_on(b2) == pawn)
1159 if (!pos.square_is_empty(b3))
1160 penalty = 2*TrappedBishopA1H1Penalty;
1161 else if (pos.piece_on(c3) == pawn)
1162 penalty = TrappedBishopA1H1Penalty;
1164 penalty = TrappedBishopA1H1Penalty / 2;
1166 ei.value -= Sign[us] * Score(penalty, penalty);
1171 // evaluate_space() computes the space evaluation for a given side. The
1172 // space evaluation is a simple bonus based on the number of safe squares
1173 // available for minor pieces on the central four files on ranks 2--4. Safe
1174 // squares one, two or three squares behind a friendly pawn are counted
1175 // twice. Finally, the space bonus is scaled by a weight taken from the
1176 // material hash table.
1177 template<Color Us, bool HasPopCnt>
1178 void evaluate_space(const Position& pos, EvalInfo& ei) {
1180 const Color Them = (Us == WHITE ? BLACK : WHITE);
1182 // Find the safe squares for our pieces inside the area defined by
1183 // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
1184 // pawn, or if it is undefended and attacked by an enemy piece.
1186 Bitboard safeSquares = SpaceMask[Us]
1187 & ~pos.pieces(PAWN, Us)
1188 & ~ei.attacked_by(Them, PAWN)
1189 & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
1191 // Find all squares which are at most three squares behind some friendly
1193 Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
1194 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
1195 behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
1197 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1198 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1200 ei.value += Sign[Us] * apply_weight(Score(space * ei.mi->space_weight(), 0), WeightSpace, 0);
1204 // apply_weight() applies an evaluation weight to a value
1206 inline Score apply_weight(Score v, int wmg, int weg) {
1207 return Score(v.mg() * wmg, v.eg() * weg) / 0x100;
1211 // scale_by_game_phase() interpolates between a middle game and an endgame
1212 // score, based on game phase. It also scales the return value by a
1213 // ScaleFactor array.
1215 Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
1217 assert(v.mg() > -VALUE_INFINITE && v.mg() < VALUE_INFINITE);
1218 assert(v.eg() > -VALUE_INFINITE && v.eg() < VALUE_INFINITE);
1219 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1221 Value ev = apply_scale_factor(v.eg(), sf[(v.eg() > Value(0) ? WHITE : BLACK)]);
1223 Value result = Value(int((v.mg() * ph + ev * (128 - ph)) / 128));
1224 return Value(int(result) & ~(GrainSize - 1));
1228 // weight_option() computes the value of an evaluation weight, by combining
1229 // an UCI-configurable weight with an internal weight.
1231 int weight_option(const std::string& opt, int internalWeight) {
1233 int uciWeight = get_option_value_int(opt);
1234 uciWeight = (uciWeight * 0x100) / 100;
1235 return (uciWeight * internalWeight) / 0x100;
1239 // init_safety() initizes the king safety evaluation, based on UCI
1240 // parameters. It is called from read_weights().
1242 void init_safety() {
1244 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1245 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1246 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1247 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1248 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1249 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1250 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1252 int maxSlope = get_option_value_int("King Safety Max Slope");
1253 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1254 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1255 double b = get_option_value_int("King Safety X Intercept");
1256 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1257 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1259 for (int i = 0; i < 100; i++)
1262 SafetyTable[i] = Value(0);
1264 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1266 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1269 for (int i = 0; i < 100; i++)
1271 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1272 for (int j = i + 1; j < 100; j++)
1273 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1275 if (SafetyTable[i] > Value(peak))
1276 SafetyTable[i] = Value(peak);
1281 std::ostream& operator<<(std::ostream &os, Score s) {
1283 return os << "(" << s.mg() << ", " << s.eg() << ")";