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 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/>.
33 #include "ucioption.h"
37 //// Local definitions
42 const int Sign[2] = {1, -1};
44 // Evaluation grain size, must be a power of 2.
45 const int GrainSize = 4;
48 int WeightMobilityMidgame = 0x100;
49 int WeightMobilityEndgame = 0x100;
50 int WeightPawnStructureMidgame = 0x100;
51 int WeightPawnStructureEndgame = 0x100;
52 int WeightPassedPawnsMidgame = 0x100;
53 int WeightPassedPawnsEndgame = 0x100;
54 int WeightKingSafety[2] = { 0x100, 0x100 };
57 // Internal evaluation weights. These are applied on top of the evaluation
58 // weights read from UCI parameters. The purpose is to be able to change
59 // the evaluation weights while keeping the default values of the UCI
60 // parameters at 100, which looks prettier.
61 const int WeightMobilityMidgameInternal = 0x100;
62 const int WeightMobilityEndgameInternal = 0x100;
63 const int WeightPawnStructureMidgameInternal = 0x100;
64 const int WeightPawnStructureEndgameInternal = 0x100;
65 const int WeightPassedPawnsMidgameInternal = 0x100;
66 const int WeightPassedPawnsEndgameInternal = 0x100;
67 const int WeightKingSafetyInternal = 0x100;
68 const int WeightKingOppSafetyInternal = 0x100;
69 const int WeightSpaceInternal = 0x30;
71 // Visually better to define tables constants
74 // Knight mobility bonus in middle game and endgame, indexed by the number
75 // of attacked squares not occupied by friendly piecess.
76 const Value MidgameKnightMobilityBonus[] = {
78 V(-30), V(-20),V(-10), V(0), V(10), V(20), V(25), V(30), V(30)
81 const Value EndgameKnightMobilityBonus[] = {
83 V(-30), V(-20),V(-10), V(0), V(10), V(20), V(25), V(30), V(30)
86 // Bishop mobility bonus in middle game and endgame, indexed by the number
87 // of attacked squares not occupied by friendly pieces. X-ray attacks through
88 // queens are also included.
89 const Value MidgameBishopMobilityBonus[] = {
91 V(-30), V(-15), V(0), V(15), V(30), V(45), V(58), V(66),
92 // 8 9 10 11 12 13 14 15
93 V( 72), V( 76), V(78), V(80), V(81), V(82), V(83), V(83)
96 const Value EndgameBishopMobilityBonus[] = {
98 V(-30), V(-15), V(0), V(15), V(30), V(45), V(58), V(66),
99 // 8 9 10 11 12 13 14 15
100 V( 72), V( 76), V(78), V(80), V(81), V(82), V(83), V(83)
103 // Rook mobility bonus in middle game and endgame, indexed by the number
104 // of attacked squares not occupied by friendly pieces. X-ray attacks through
105 // queens and rooks are also included.
106 const Value MidgameRookMobilityBonus[] = {
108 V(-18), V(-12), V(-6), V(0), V(6), V(12), V(16), V(21),
109 // 8 9 10 11 12 13 14 15
110 V( 24), V( 27), V(28), V(29), V(30), V(31), V(32), V(33)
113 const Value EndgameRookMobilityBonus[] = {
115 V(-30), V(-18), V(-6), V(6), V(18), V(30), V(42), V(54),
116 // 8 9 10 11 12 13 14 15
117 V( 66), V( 74), V(78), V(80), V(81), V(82), V(83), V(83)
120 // Queen mobility bonus in middle game and endgame, indexed by the number
121 // of attacked squares not occupied by friendly pieces.
122 const Value MidgameQueenMobilityBonus[] = {
124 V(-10), V(-8), V(-6), V(-4), V(-2), V( 0), V( 2), V( 4),
125 // 8 9 10 11 12 13 14 15
126 V( 6), V( 8), V(10), V(12), V(13), V(14), V(15), V(16),
127 // 16 17 18 19 20 21 22 23
128 V( 16), V(16), V(16), V(16), V(16), V(16), V(16), V(16),
129 // 24 25 26 27 28 29 30 31
130 V( 16), V(16), V(16), V(16), V(16), V(16), V(16), V(16)
133 const Value EndgameQueenMobilityBonus[] = {
135 V(-20),V(-15),V(-10), V(-5), V( 0), V( 5), V(10), V(15),
136 // 8 9 10 11 12 13 14 15
137 V( 19), V(23), V(27), V(29), V(30), V(30), V(30), V(30),
138 // 16 17 18 19 20 21 22 23
139 V( 30), V(30), V(30), V(30), V(30), V(30), V(30), V(30),
140 // 24 25 26 27 28 29 30 31
141 V( 30), V(30), V(30), V(30), V(30), V(30), V(30), V(30)
144 // Outpost bonuses for knights and bishops, indexed by square (from white's
146 const Value KnightOutpostBonus[64] = {
148 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
149 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
150 V(0), V(0), V(5),V(10),V(10), V(5), V(0), V(0), // 3
151 V(0), V(5),V(20),V(30),V(30),V(20), V(5), V(0), // 4
152 V(0),V(10),V(30),V(40),V(40),V(30),V(10), V(0), // 5
153 V(0), V(5),V(20),V(20),V(20),V(20), V(5), V(0), // 6
154 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
155 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
158 const Value BishopOutpostBonus[64] = {
160 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
161 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
162 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
163 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
164 V(0),V(10),V(20),V(20),V(20),V(20),V(10), V(0), // 5
165 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
166 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
167 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
170 // Bonus for unstoppable passed pawns:
171 const Value UnstoppablePawnValue = Value(0x500);
173 // Rooks and queens on the 7th rank:
174 const Value MidgameRookOn7thBonus = Value(50);
175 const Value EndgameRookOn7thBonus = Value(100);
176 const Value MidgameQueenOn7thBonus = Value(25);
177 const Value EndgameQueenOn7thBonus = Value(50);
179 // Rooks on open files:
180 const Value RookOpenFileBonus = Value(40);
181 const Value RookHalfOpenFileBonus = Value(20);
183 // Penalty for rooks trapped inside a friendly king which has lost the
185 const Value TrappedRookPenalty = Value(180);
187 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
189 const Value TrappedBishopA7H7Penalty = Value(300);
191 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black):
192 const Bitboard MaskA7H7[2] = {
193 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
194 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
197 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
198 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
199 // happen in Chess960 games.
200 const Value TrappedBishopA1H1Penalty = Value(100);
202 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black):
203 const Bitboard MaskA1H1[2] = {
204 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
205 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
208 // The SpaceMask[color] contains area of the board which is consdered by
209 // the space evaluation. In the middle game, each side is given a bonus
210 // based on how many squares inside this area are safe and available for
211 // friendly minor pieces.
212 const Bitboard SpaceMask[2] = {
213 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
214 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
215 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
216 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
217 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
218 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
221 /// King safety constants and variables. The king safety scores are taken
222 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
223 /// the strength of the attack are added up into an integer, which is used
224 /// as an index to SafetyTable[].
226 // Attack weights for each piece type.
227 const int QueenAttackWeight = 5;
228 const int RookAttackWeight = 3;
229 const int BishopAttackWeight = 2;
230 const int KnightAttackWeight = 2;
232 // Bonuses for safe checks for each piece type.
233 int QueenContactCheckBonus = 4;
234 int RookContactCheckBonus = 2;
235 int QueenCheckBonus = 2;
236 int RookCheckBonus = 1;
237 int BishopCheckBonus = 1;
238 int KnightCheckBonus = 1;
239 int DiscoveredCheckBonus = 3;
241 // Scan for queen contact mates?
242 const bool QueenContactMates = true;
244 // Bonus for having a mate threat.
245 int MateThreatBonus = 3;
247 // InitKingDanger[] contains bonuses based on the position of the defending
249 const int InitKingDanger[64] = {
250 2, 0, 2, 5, 5, 2, 0, 2,
251 2, 2, 4, 8, 8, 4, 2, 2,
252 7, 10, 12, 12, 12, 12, 10, 7,
253 15, 15, 15, 15, 15, 15, 15, 15,
254 15, 15, 15, 15, 15, 15, 15, 15,
255 15, 15, 15, 15, 15, 15, 15, 15,
256 15, 15, 15, 15, 15, 15, 15, 15,
257 15, 15, 15, 15, 15, 15, 15, 15
260 // SafetyTable[] contains the actual king safety scores. It is initialized
262 Value SafetyTable[100];
264 // Pawn and material hash tables, indexed by the current thread id
265 PawnInfoTable *PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
266 MaterialInfoTable *MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
268 // Sizes of pawn and material hash tables
269 const int PawnTableSize = 16384;
270 const int MaterialTableSize = 1024;
272 // Array which gives the number of nonzero bits in an 8-bit integer:
273 uint8_t BitCount8Bit[256];
275 // Function prototypes
276 void evaluate_knight(const Position &p, Square s, Color us, EvalInfo &ei);
277 void evaluate_bishop(const Position &p, Square s, Color us, EvalInfo &ei);
278 void evaluate_rook(const Position &p, Square s, Color us, EvalInfo &ei);
279 void evaluate_queen(const Position &p, Square s, Color us, EvalInfo &ei);
280 void evaluate_king(const Position &p, Square s, Color us, EvalInfo &ei);
282 void evaluate_passed_pawns(const Position &pos, EvalInfo &ei);
283 void evaluate_trapped_bishop_a7h7(const Position &pos, Square s, Color us,
285 void evaluate_trapped_bishop_a1h1(const Position &pos, Square s, Color us,
288 void evaluate_space(const Position &p, Color us, EvalInfo &ei);
289 inline Value apply_weight(Value v, int w);
290 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
292 int count_1s_8bit(Bitboard b);
294 int compute_weight(int uciWeight, int internalWeight);
295 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.
309 Value evaluate(const Position &pos, EvalInfo &ei, int threadID) {
312 assert(threadID >= 0 && threadID < THREAD_MAX);
314 memset(&ei, 0, sizeof(EvalInfo));
316 // Initialize by reading the incrementally updated scores included in the
317 // position object (material + piece square tables)
318 ei.mgValue = pos.mg_value();
319 ei.egValue = pos.eg_value();
321 // Probe the material hash table
322 ei.mi = MaterialTable[threadID]->get_material_info(pos);
323 ei.mgValue += ei.mi->mg_value();
324 ei.egValue += ei.mi->eg_value();
326 // If we have a specialized evaluation function for the current material
327 // configuration, call it and return
328 if (ei.mi->specialized_eval_exists())
329 return ei.mi->evaluate(pos);
331 // After get_material_info() call that modifies them
332 ScaleFactor factor[2];
333 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
334 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
336 // Probe the pawn hash table
337 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
338 ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
339 ei.egValue += apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame);
341 // Initialize king attack bitboards and king attack zones for both sides
342 ei.attackedBy[WHITE][KING] = pos.piece_attacks<KING>(pos.king_square(WHITE));
343 ei.attackedBy[BLACK][KING] = pos.piece_attacks<KING>(pos.king_square(BLACK));
344 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
345 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
347 // Initialize pawn attack bitboards for both sides
348 ei.attackedBy[WHITE][PAWN] = ((pos.pawns(WHITE) << 9) & ~FileABB) | ((pos.pawns(WHITE) << 7) & ~FileHBB);
349 ei.attackedBy[BLACK][PAWN] = ((pos.pawns(BLACK) >> 7) & ~FileABB) | ((pos.pawns(BLACK) >> 9) & ~FileHBB);
350 ei.kingAttackersCount[WHITE] = count_1s_max_15(ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING])/2;
351 ei.kingAttackersCount[BLACK] = count_1s_max_15(ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING])/2;
354 for (Color c = WHITE; c <= BLACK; c++)
357 for (int i = 0; i < pos.piece_count(c, KNIGHT); i++)
358 evaluate_knight(pos, pos.piece_list(c, KNIGHT, i), c, ei);
361 for (int i = 0; i < pos.piece_count(c, BISHOP); i++)
362 evaluate_bishop(pos, pos.piece_list(c, BISHOP, i), c, ei);
365 for (int i = 0; i < pos.piece_count(c, ROOK); i++)
366 evaluate_rook(pos, pos.piece_list(c, ROOK, i), c, ei);
369 for(int i = 0; i < pos.piece_count(c, QUEEN); i++)
370 evaluate_queen(pos, pos.piece_list(c, QUEEN, i), c, ei);
372 // Special pattern: trapped bishops on a7/h7/a2/h2
373 Bitboard b = pos.bishops(c) & MaskA7H7[c];
376 Square s = pop_1st_bit(&b);
377 evaluate_trapped_bishop_a7h7(pos, s, c, ei);
380 // Special pattern: trapped bishops on a1/h1/a8/h8 in Chess960:
383 b = pos.bishops(c) & MaskA1H1[c];
386 Square s = pop_1st_bit(&b);
387 evaluate_trapped_bishop_a1h1(pos, s, c, ei);
391 // Sum up all attacked squares
392 ei.attackedBy[c][0] = ei.attackedBy[c][PAWN] | ei.attackedBy[c][KNIGHT]
393 | ei.attackedBy[c][BISHOP] | ei.attackedBy[c][ROOK]
394 | ei.attackedBy[c][QUEEN] | ei.attackedBy[c][KING];
397 // Kings. Kings are evaluated after all other pieces for both sides,
398 // because we need complete attack information for all pieces when computing
399 // the king safety evaluation.
400 for (Color c = WHITE; c <= BLACK; c++)
401 evaluate_king(pos, pos.king_square(c), c, ei);
403 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
404 // because we need to know which side promotes first in positions where
405 // both sides have an unstoppable passed pawn.
406 if (ei.pi->passed_pawns())
407 evaluate_passed_pawns(pos, ei);
409 Phase phase = pos.game_phase();
411 // Middle-game specific evaluation terms
412 if (phase > PHASE_ENDGAME)
414 // Pawn storms in positions with opposite castling.
415 if ( square_file(pos.king_square(WHITE)) >= FILE_E
416 && square_file(pos.king_square(BLACK)) <= FILE_D)
418 ei.mgValue += ei.pi->queenside_storm_value(WHITE)
419 - ei.pi->kingside_storm_value(BLACK);
421 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
422 && square_file(pos.king_square(BLACK)) >= FILE_E)
424 ei.mgValue += ei.pi->kingside_storm_value(WHITE)
425 - ei.pi->queenside_storm_value(BLACK);
427 // Evaluate space for both sides
428 if (ei.mi->space_weight() > 0)
430 evaluate_space(pos, WHITE, ei);
431 evaluate_space(pos, BLACK, ei);
436 ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
437 ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
439 // If we don't already have an unusual scale factor, check for opposite
440 // colored bishop endgames, and use a lower scale for those
441 if ( phase < PHASE_MIDGAME
442 && pos.opposite_colored_bishops()
443 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
444 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
448 // Only the two bishops ?
449 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
450 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
452 // Check for KBP vs KB with only a single pawn that is almost
453 // certainly a draw or at least two pawns.
454 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
455 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
458 // Endgame with opposite-colored bishops, but also other pieces. Still
459 // a bit drawish, but not as drawish as with only the two bishops.
460 sf = ScaleFactor(50);
462 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
464 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
468 // Interpolate between the middle game and the endgame score, and
470 Color stm = pos.side_to_move();
472 Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
474 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
478 /// quick_evaluate() does a very approximate evaluation of the current position.
479 /// It currently considers only material and piece square table scores. Perhaps
480 /// we should add scores from the pawn and material hash tables?
482 Value quick_evaluate(const Position &pos) {
487 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
489 Value mgv = pos.mg_value();
490 Value egv = pos.eg_value();
491 Phase ph = pos.game_phase();
492 Color stm = pos.side_to_move();
494 return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
498 /// init_eval() initializes various tables used by the evaluation function.
500 void init_eval(int threads) {
502 assert(threads <= THREAD_MAX);
504 for (int i = 0; i < THREAD_MAX; i++)
509 delete MaterialTable[i];
511 MaterialTable[i] = NULL;
515 PawnTable[i] = new PawnInfoTable(PawnTableSize);
516 if (!MaterialTable[i])
517 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
520 for (Bitboard b = 0ULL; b < 256ULL; b++)
521 BitCount8Bit[b] = count_1s(b);
525 /// quit_eval() releases heap-allocated memory at program termination.
529 for (int i = 0; i < THREAD_MAX; i++)
532 delete MaterialTable[i];
537 /// read_weights() reads evaluation weights from the corresponding UCI
540 void read_weights(Color us) {
542 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
543 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
544 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
545 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
546 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
547 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
549 Color them = opposite_color(us);
551 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
552 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
553 WeightSpace = weight_option("Space", WeightSpaceInternal);
561 // evaluate_common() computes terms common to all pieces attack
563 int evaluate_common(const Position&p, const Bitboard& b, Color us, EvalInfo& ei,
564 int AttackWeight, const Value* mgBonus, const Value* egBonus,
565 Square s = SQ_NONE, const Value* OutpostBonus = NULL) {
567 Color them = opposite_color(us);
570 if (b & ei.kingZone[us])
572 ei.kingAttackersCount[us]++;
573 ei.kingAttackersWeight[us] += AttackWeight;
574 Bitboard bb = (b & ei.attackedBy[them][KING]);
576 ei.kingAdjacentZoneAttacksCount[us] += count_1s_max_15(bb);
580 int mob = count_1s_max_15(b & ~p.pieces_of_color(us));
581 ei.mgMobility += Sign[us] * mgBonus[mob];
582 ei.egMobility += Sign[us] * egBonus[mob];
584 // Bishop and Knight outposts
585 if (!OutpostBonus || !p.square_is_weak(s, them))
588 // Initial bonus based on square
590 v = bonus = OutpostBonus[relative_square(us, s)];
592 // Increase bonus if supported by pawn, especially if the opponent has
593 // no minor piece which can exchange the outpost piece
594 if (v && (p.pawn_attacks(them, s) & p.pawns(us)))
597 if ( p.piece_count(them, KNIGHT) == 0
598 && (SquaresByColorBB[square_color(s)] & p.bishops(them)) == EmptyBoardBB)
601 ei.mgValue += Sign[us] * bonus;
602 ei.egValue += Sign[us] * bonus;
607 // evaluate_knight() assigns bonuses and penalties to a knight of a given
608 // color on a given square.
610 void evaluate_knight(const Position &p, Square s, Color us, EvalInfo &ei) {
612 Bitboard b = p.piece_attacks<KNIGHT>(s);
613 ei.attackedBy[us][KNIGHT] |= b;
615 // King attack, mobility and outposts
616 evaluate_common(p, b, us, ei, KnightAttackWeight, MidgameKnightMobilityBonus,
617 EndgameKnightMobilityBonus, s, KnightOutpostBonus);
621 // evaluate_bishop() assigns bonuses and penalties to a bishop of a given
622 // color on a given square.
624 void evaluate_bishop(const Position &p, Square s, Color us, EvalInfo &ei) {
626 Bitboard b = bishop_attacks_bb(s, p.occupied_squares() & ~p.queens(us));
627 ei.attackedBy[us][BISHOP] |= b;
629 // King attack, mobility and outposts
630 evaluate_common(p, b, us, ei, BishopAttackWeight, MidgameBishopMobilityBonus,
631 EndgameBishopMobilityBonus, s, BishopOutpostBonus);
635 // evaluate_rook() assigns bonuses and penalties to a rook of a given
636 // color on a given square.
638 void evaluate_rook(const Position &p, Square s, Color us, EvalInfo &ei) {
640 //Bitboard b = p.rook_attacks(s);
641 Bitboard b = rook_attacks_bb(s, p.occupied_squares() & ~p.rooks_and_queens(us));
642 ei.attackedBy[us][ROOK] |= b;
644 // King attack and mobility
645 int mob = evaluate_common(p, b, us, ei, RookAttackWeight, MidgameRookMobilityBonus,
646 EndgameRookMobilityBonus);
649 Color them = opposite_color(us);
651 if ( relative_rank(us, s) == RANK_7
652 && relative_rank(us, p.king_square(them)) == RANK_8)
654 ei.mgValue += Sign[us] * MidgameRookOn7thBonus;
655 ei.egValue += Sign[us] * EndgameRookOn7thBonus;
658 // Open and half-open files
659 File f = square_file(s);
660 if (ei.pi->file_is_half_open(us, f))
662 if (ei.pi->file_is_half_open(them, f))
664 ei.mgValue += Sign[us] * RookOpenFileBonus;
665 ei.egValue += Sign[us] * RookOpenFileBonus;
669 ei.mgValue += Sign[us] * RookHalfOpenFileBonus;
670 ei.egValue += Sign[us] * RookHalfOpenFileBonus;
674 // Penalize rooks which are trapped inside a king. Penalize more if
675 // king has lost right to castle
676 if (mob > 6 || ei.pi->file_is_half_open(us, f))
679 Square ksq = p.king_square(us);
681 if ( square_file(ksq) >= FILE_E
682 && square_file(s) > square_file(ksq)
683 && (relative_rank(us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
685 // Is there a half-open file between the king and the edge of the board?
686 if (!ei.pi->has_open_file_to_right(us, square_file(ksq)))
687 ei.mgValue -= p.can_castle(us)? Sign[us] * ((TrappedRookPenalty - mob * 16) / 2)
688 : Sign[us] * (TrappedRookPenalty - mob * 16);
690 else if ( square_file(ksq) <= FILE_D
691 && square_file(s) < square_file(ksq)
692 && (relative_rank(us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
694 // Is there a half-open file between the king and the edge of the board?
695 if (!ei.pi->has_open_file_to_left(us, square_file(ksq)))
696 ei.mgValue -= p.can_castle(us)? Sign[us] * ((TrappedRookPenalty - mob * 16) / 2)
697 : Sign[us] * (TrappedRookPenalty - mob * 16);
702 // evaluate_queen() assigns bonuses and penalties to a queen of a given
703 // color on a given square.
705 void evaluate_queen(const Position &p, Square s, Color us, EvalInfo &ei) {
707 Bitboard b = p.piece_attacks<QUEEN>(s);
708 ei.attackedBy[us][QUEEN] |= b;
710 // King attack and mobility
711 evaluate_common(p, b, us, ei, QueenAttackWeight, MidgameQueenMobilityBonus,
712 EndgameQueenMobilityBonus);
715 Color them = opposite_color(us);
717 if ( relative_rank(us, s) == RANK_7
718 && relative_rank(us, p.king_square(them)) == RANK_8)
720 ei.mgValue += Sign[us] * MidgameQueenOn7thBonus;
721 ei.egValue += Sign[us] * EndgameQueenOn7thBonus;
725 inline Bitboard shiftRowsDown(const Bitboard& b, int num) {
727 return b >> (num << 3);
730 // evaluate_king() assigns bonuses and penalties to a king of a given
731 // color on a given square.
733 void evaluate_king(const Position &p, Square s, Color us, EvalInfo &ei) {
735 int shelter = 0, sign = Sign[us];
738 if (relative_rank(us, s) <= RANK_4)
740 Bitboard pawns = p.pawns(us) & this_and_neighboring_files_bb(s);
741 Rank r = square_rank(s);
742 for (int i = 1; i < 4; i++)
743 shelter += count_1s_8bit(shiftRowsDown(pawns, r+i*sign)) * (128>>i);
745 ei.mgValue += sign * Value(shelter);
748 // King safety. This is quite complicated, and is almost certainly far
749 // from optimally tuned.
750 Color them = opposite_color(us);
752 if ( p.piece_count(them, QUEEN) >= 1
753 && ei.kingAttackersCount[them] >= 2
754 && p.non_pawn_material(them) >= QueenValueMidgame + RookValueMidgame
755 && ei.kingAdjacentZoneAttacksCount[them])
757 // Is it the attackers turn to move?
758 bool sente = (them == p.side_to_move());
760 // Find the attacked squares around the king which has no defenders
761 // apart from the king itself
762 Bitboard undefended =
763 ei.attacked_by(them) & ~ei.attacked_by(us, PAWN)
764 & ~ei.attacked_by(us, KNIGHT) & ~ei.attacked_by(us, BISHOP)
765 & ~ei.attacked_by(us, ROOK) & ~ei.attacked_by(us, QUEEN)
766 & ei.attacked_by(us, KING);
768 Bitboard occ = p.occupied_squares(), b, b2;
770 // Initialize the 'attackUnits' variable, which is used later on as an
771 // index to the SafetyTable[] array. The initial is based on the number
772 // and types of the attacking pieces, the number of attacked and
773 // undefended squares around the king, the square of the king, and the
774 // quality of the pawn shelter.
776 Min((ei.kingAttackersCount[them] * ei.kingAttackersWeight[them]) / 2, 25)
777 + (ei.kingAdjacentZoneAttacksCount[them] + count_1s_max_15(undefended)) * 3
778 + InitKingDanger[relative_square(us, s)] - shelter / 32;
780 // Analyse safe queen contact checks
781 b = undefended & ei.attacked_by(them, QUEEN) & ~p.pieces_of_color(them);
784 Bitboard attackedByOthers =
785 ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
786 | ei.attacked_by(them, BISHOP) | ei.attacked_by(them, ROOK);
788 b &= attackedByOthers;
791 // The bitboard b now contains the squares available for safe queen
793 int count = count_1s_max_15(b);
794 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
796 // Is there a mate threat?
797 if (QueenContactMates && !p.is_check())
799 Bitboard escapeSquares =
800 p.piece_attacks<KING>(s) & ~p.pieces_of_color(us) & ~attackedByOthers;
804 Square from, to = pop_1st_bit(&b);
805 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
807 // We have a mate, unless the queen is pinned or there
808 // is an X-ray attack through the queen.
809 for (int i = 0; i < p.piece_count(them, QUEEN); i++)
811 from = p.piece_list(them, QUEEN, i);
812 if ( bit_is_set(p.piece_attacks<QUEEN>(from), to)
813 && !bit_is_set(p.pinned_pieces(them), from)
814 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & p.rooks_and_queens(us))
815 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & p.rooks_and_queens(us)))
817 ei.mateThreat[them] = make_move(from, to);
824 // Analyse safe rook contact checks:
825 if (RookContactCheckBonus)
827 b = undefended & ei.attacked_by(them, ROOK) & ~p.pieces_of_color(them);
830 Bitboard attackedByOthers =
831 ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
832 | ei.attacked_by(them, BISHOP) | ei.attacked_by(them, QUEEN);
834 b &= attackedByOthers;
837 int count = count_1s_max_15(b);
838 attackUnits += (RookContactCheckBonus * count * (sente? 2 : 1));
842 // Analyse safe distance checks:
843 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
845 b = p.piece_attacks<ROOK>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
848 b2 = b & ei.attacked_by(them, QUEEN);
850 attackUnits += QueenCheckBonus * count_1s_max_15(b2);
853 b2 = b & ei.attacked_by(them, ROOK);
855 attackUnits += RookCheckBonus * count_1s_max_15(b2);
857 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
859 b = p.piece_attacks<BISHOP>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
862 b2 = b & ei.attacked_by(them, QUEEN);
864 attackUnits += QueenCheckBonus * count_1s_max_15(b2);
867 b2 = b & ei.attacked_by(them, BISHOP);
869 attackUnits += BishopCheckBonus * count_1s_max_15(b2);
871 if (KnightCheckBonus > 0)
873 b = p.piece_attacks<KNIGHT>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
876 b2 = b & ei.attacked_by(them, KNIGHT);
878 attackUnits += KnightCheckBonus * count_1s_max_15(b2);
881 // Analyse discovered checks (only for non-pawns right now, consider
882 // adding pawns later).
883 if (DiscoveredCheckBonus)
885 b = p.discovered_check_candidates(them) & ~p.pawns();
887 attackUnits += DiscoveredCheckBonus * count_1s_max_15(b) * (sente? 2 : 1);
890 // Has a mate threat been found? We don't do anything here if the
891 // side with the mating move is the side to move, because in that
892 // case the mating side will get a huge bonus at the end of the main
893 // evaluation function instead.
894 if (ei.mateThreat[them] != MOVE_NONE)
895 attackUnits += MateThreatBonus;
897 // Ensure that attackUnits is between 0 and 99, in order to avoid array
898 // out of bounds errors:
902 if (attackUnits >= 100)
905 // Finally, extract the king safety score from the SafetyTable[] array.
906 // Add the score to the evaluation, and also to ei.futilityMargin. The
907 // reason for adding the king safety score to the futility margin is
908 // that the king safety scores can sometimes be very big, and that
909 // capturing a single attacking piece can therefore result in a score
910 // change far bigger than the value of the captured piece.
911 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[us]);
913 ei.mgValue -= sign * v;
915 if (us == p.side_to_move())
916 ei.futilityMargin += v;
921 // evaluate_passed_pawns() evaluates the passed pawns for both sides.
923 void evaluate_passed_pawns(const Position &pos, EvalInfo &ei) {
924 bool hasUnstoppable[2] = {false, false};
925 int movesToGo[2] = {100, 100};
927 for(Color us = WHITE; us <= BLACK; us++) {
928 Color them = opposite_color(us);
929 Square ourKingSq = pos.king_square(us);
930 Square theirKingSq = pos.king_square(them);
931 Bitboard b = ei.pi->passed_pawns() & pos.pawns(us), b2, b3, b4;
934 Square s = pop_1st_bit(&b);
935 assert(pos.piece_on(s) == pawn_of_color(us));
936 assert(pos.pawn_is_passed(us, s));
938 int r = int(relative_rank(us, s) - RANK_2);
939 int tr = Max(0, r * (r-1));
940 Square blockSq = s + pawn_push(us);
942 // Base bonus based on rank:
943 Value mbonus = Value(20 * tr);
944 Value ebonus = Value(10 + r * r * 10);
946 // Adjust bonus based on king proximity:
947 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
949 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 b2 = squares_in_front_of(us, s);
956 b3 = b2 & ei.attacked_by(them);
957 b4 = b2 & ei.attacked_by(us);
958 if((b2 & pos.pieces_of_color(them)) == EmptyBoardBB) {
959 // There are no enemy pieces in the pawn's path! Are any of the
960 // squares in the pawn's path attacked by the enemy?
961 if(b3 == EmptyBoardBB)
962 // No enemy attacks, huge bonus!
963 ebonus += Value(tr * ((b2 == b4)? 17 : 15));
965 // OK, there are enemy attacks. Are those squares which are
966 // attacked by the enemy also attacked by us? If yes, big bonus
967 // (but smaller than when there are no enemy attacks), if no,
968 // somewhat smaller bonus.
969 ebonus += Value(tr * (((b3 & b4) == b3)? 13 : 8));
972 // There are some enemy pieces in the pawn's path. While this is
973 // sad, we still assign a moderate bonus if all squares in the path
974 // which are either occupied by or attacked by enemy pieces are
975 // also attacked by us.
976 if(((b3 | (b2 & pos.pieces_of_color(them))) & ~b4) == EmptyBoardBB)
977 ebonus += Value(tr * 6);
979 // At last, add a small bonus when there are no *friendly* pieces
980 // in the pawn's path:
981 if((b2 & pos.pieces_of_color(us)) == EmptyBoardBB)
985 // If the pawn is supported by a friendly pawn, increase bonus.
986 b2 = pos.pawns(us) & neighboring_files_bb(s);
988 ebonus += Value(r * 20);
989 else if(pos.pawn_attacks(them, s) & b2)
990 ebonus += Value(r * 12);
992 // If the other side has only a king, check whether the pawn is
994 if(pos.non_pawn_material(them) == Value(0)) {
998 qsq = relative_square(us, make_square(square_file(s), RANK_8));
999 d = square_distance(s, qsq) - square_distance(theirKingSq, qsq)
1000 + ((us == pos.side_to_move())? 0 : 1);
1003 int mtg = RANK_8 - relative_rank(us, s);
1005 count_1s_max_15(squares_in_front_of(us,s)&pos.occupied_squares());
1006 mtg += blockerCount;
1009 hasUnstoppable[us] = true;
1010 movesToGo[us] = Min(movesToGo[us], mtg);
1014 // Rook pawns are a special case: They are sometimes worse, and
1015 // sometimes better than other passed pawns. It is difficult to find
1016 // good rules for determining whether they are good or bad. For now,
1017 // we try the following: Increase the value for rook pawns if the
1018 // other side has no pieces apart from a knight, and decrease the
1019 // value if the other side has a rook or queen.
1020 if(square_file(s) == FILE_A || square_file(s) == FILE_H) {
1021 if(pos.non_pawn_material(them) == KnightValueMidgame
1022 && pos.piece_count(them, KNIGHT) == 1)
1023 ebonus += ebonus / 4;
1024 else if(pos.rooks_and_queens(them))
1025 ebonus -= ebonus / 4;
1028 // Add the scores for this pawn to the middle game and endgame eval.
1029 ei.mgValue += apply_weight(Sign[us] * mbonus, WeightPassedPawnsMidgame);
1030 ei.egValue += apply_weight(Sign[us] * ebonus, WeightPassedPawnsEndgame);
1034 // Does either side have an unstoppable passed pawn?
1035 if(hasUnstoppable[WHITE] && !hasUnstoppable[BLACK])
1036 ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]);
1037 else if(hasUnstoppable[BLACK] && !hasUnstoppable[WHITE])
1038 ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]);
1039 else if(hasUnstoppable[BLACK] && hasUnstoppable[WHITE]) {
1040 // Both sides have unstoppable pawns! Try to find out who queens
1041 // first. We begin by transforming 'movesToGo' to the number of
1042 // plies until the pawn queens for both sides:
1043 movesToGo[WHITE] *= 2;
1044 movesToGo[BLACK] *= 2;
1045 movesToGo[pos.side_to_move()]--;
1047 // If one side queens at least three plies before the other, that
1049 if(movesToGo[WHITE] <= movesToGo[BLACK] - 3)
1050 ei.egValue += UnstoppablePawnValue - Value(0x40 * (movesToGo[WHITE]/2));
1051 else if(movesToGo[BLACK] <= movesToGo[WHITE] - 3)
1052 ei.egValue -= UnstoppablePawnValue - Value(0x40 * (movesToGo[BLACK]/2));
1054 // We could also add some rules about the situation when one side
1055 // queens exactly one ply before the other: Does the first queen
1056 // check the opponent's king, or attack the opponent's queening square?
1057 // This is slightly tricky to get right, because it is possible that
1058 // the opponent's king has moved somewhere before the first pawn queens.
1063 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1064 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1067 void evaluate_trapped_bishop_a7h7(const Position &pos, Square s, Color us,
1070 assert(square_is_ok(s));
1071 assert(pos.piece_on(s) == bishop_of_color(us));
1073 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1074 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1076 if ( pos.piece_on(b6) == pawn_of_color(opposite_color(us))
1077 && pos.see(s, b6) < 0
1078 && pos.see(s, b8) < 0)
1080 ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
1081 ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
1086 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1087 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1088 // black), and assigns a penalty if it is. This pattern can obviously
1089 // only occur in Chess960 games.
1091 void evaluate_trapped_bishop_a1h1(const Position &pos, Square s, Color us,
1093 Piece pawn = pawn_of_color(us);
1097 assert(square_is_ok(s));
1098 assert(pos.piece_on(s) == bishop_of_color(us));
1100 if(square_file(s) == FILE_A) {
1101 b2 = relative_square(us, SQ_B2);
1102 b3 = relative_square(us, SQ_B3);
1103 c3 = relative_square(us, SQ_C3);
1106 b2 = relative_square(us, SQ_G2);
1107 b3 = relative_square(us, SQ_G3);
1108 c3 = relative_square(us, SQ_F3);
1111 if(pos.piece_on(b2) == pawn) {
1114 if(!pos.square_is_empty(b3))
1115 penalty = 2*TrappedBishopA1H1Penalty;
1116 else if(pos.piece_on(c3) == pawn)
1117 penalty = TrappedBishopA1H1Penalty;
1119 penalty = TrappedBishopA1H1Penalty / 2;
1121 ei.mgValue -= Sign[us] * penalty;
1122 ei.egValue -= Sign[us] * penalty;
1128 // evaluate_space() computes the space evaluation for a given side. The
1129 // space evaluation is a simple bonus based on the number of safe squares
1130 // available for minor pieces on the central four files on ranks 2--4. Safe
1131 // squares one, two or three squares behind a friendly pawn are counted
1132 // twice. Finally, the space bonus is scaled by a weight taken from the
1133 // material hash table.
1135 void evaluate_space(const Position &pos, Color us, EvalInfo &ei) {
1137 Color them = opposite_color(us);
1139 // Find the safe squares for our pieces inside the area defined by
1140 // SpaceMask[us]. A square is unsafe it is attacked by an enemy
1141 // pawn, or if it is undefended and attacked by an enemy piece.
1143 Bitboard safeSquares =
1144 SpaceMask[us] & ~pos.pawns(us) & ~ei.attacked_by(them, PAWN)
1145 & ~(~ei.attacked_by(us) & ei.attacked_by(them));
1147 // Find all squares which are at most three squares behind some friendly
1149 Bitboard behindFriendlyPawns = pos.pawns(us);
1151 behindFriendlyPawns |= (behindFriendlyPawns >> 8);
1152 behindFriendlyPawns |= (behindFriendlyPawns >> 16);
1155 behindFriendlyPawns |= (behindFriendlyPawns << 8);
1156 behindFriendlyPawns |= (behindFriendlyPawns << 16);
1160 count_1s_max_15(safeSquares)
1161 + count_1s_max_15(behindFriendlyPawns & safeSquares);
1163 ei.mgValue += Sign[us] *
1164 apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
1168 // apply_weight() applies an evaluation weight to a value
1170 inline Value apply_weight(Value v, int w) {
1171 return (v*w) / 0x100;
1175 // scale_by_game_phase() interpolates between a middle game and an endgame
1176 // score, based on game phase. It also scales the return value by a
1177 // ScaleFactor array.
1179 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
1181 assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
1182 assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
1183 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1185 ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
1187 Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
1188 return Value(int(result) & ~(GrainSize - 1));
1192 // count_1s_8bit() counts the number of nonzero bits in the 8 least
1193 // significant bits of a Bitboard. This function is used by the king
1194 // shield evaluation.
1196 int count_1s_8bit(Bitboard b) {
1197 return int(BitCount8Bit[b & 0xFF]);
1201 // compute_weight() computes the value of an evaluation weight, by combining
1202 // an UCI-configurable weight with an internal weight.
1204 int compute_weight(int uciWeight, int internalWeight) {
1205 uciWeight = (uciWeight * 0x100) / 100;
1206 return (uciWeight * internalWeight) / 0x100;
1210 // helper used in read_weights()
1211 int weight_option(const std::string& opt, int weight) {
1213 return compute_weight(get_option_value_int(opt), weight);
1217 // init_safety() initizes the king safety evaluation, based on UCI
1218 // parameters. It is called from read_weights().
1220 void init_safety() {
1222 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1223 RookContactCheckBonus = get_option_value_int("Rook Contact Check Bonus");
1224 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1225 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1226 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1227 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1228 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1229 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1231 int maxSlope = get_option_value_int("King Safety Max Slope");
1232 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1233 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1234 double b = get_option_value_int("King Safety X Intercept");
1235 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1236 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1238 for (int i = 0; i < 100; i++)
1241 SafetyTable[i] = Value(0);
1243 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1245 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1248 for (int i = 0; i < 100; i++)
1250 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1251 for (int j = i + 1; j < 100; j++)
1252 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1254 if (SafetyTable[i] > Value(peak))
1255 SafetyTable[i] = Value(peak);