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 = 0x110;
68 const int WeightKingOppSafetyInternal = 0x110;
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 = 3;
234 int QueenCheckBonus = 2;
235 int RookCheckBonus = 1;
236 int BishopCheckBonus = 1;
237 int KnightCheckBonus = 1;
238 int DiscoveredCheckBonus = 3;
240 // Scan for queen contact mates?
241 const bool QueenContactMates = true;
243 // Bonus for having a mate threat.
244 int MateThreatBonus = 3;
246 // InitKingDanger[] contains bonuses based on the position of the defending
248 const int InitKingDanger[64] = {
249 2, 0, 2, 5, 5, 2, 0, 2,
250 2, 2, 4, 8, 8, 4, 2, 2,
251 7, 10, 12, 12, 12, 12, 10, 7,
252 15, 15, 15, 15, 15, 15, 15, 15,
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
259 // SafetyTable[] contains the actual king safety scores. It is initialized
261 Value SafetyTable[100];
263 // Pawn and material hash tables, indexed by the current thread id
264 PawnInfoTable *PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
265 MaterialInfoTable *MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
267 // Sizes of pawn and material hash tables
268 const int PawnTableSize = 16384;
269 const int MaterialTableSize = 1024;
271 // Array which gives the number of nonzero bits in an 8-bit integer:
272 uint8_t BitCount8Bit[256];
274 // Function prototypes
275 void evaluate_knight(const Position &p, Square s, Color us, EvalInfo &ei);
276 void evaluate_bishop(const Position &p, Square s, Color us, EvalInfo &ei);
277 void evaluate_rook(const Position &p, Square s, Color us, EvalInfo &ei);
278 void evaluate_queen(const Position &p, Square s, Color us, EvalInfo &ei);
279 void evaluate_king(const Position &p, Square s, Color us, EvalInfo &ei);
281 void evaluate_passed_pawns(const Position &pos, EvalInfo &ei);
282 void evaluate_trapped_bishop_a7h7(const Position &pos, Square s, Color us,
284 void evaluate_trapped_bishop_a1h1(const Position &pos, Square s, Color us,
287 void evaluate_space(const Position &p, Color us, EvalInfo &ei);
288 inline Value apply_weight(Value v, int w);
289 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
291 int count_1s_8bit(Bitboard b);
293 int compute_weight(int uciWeight, int internalWeight);
294 int weight_option(const std::string& opt, int weight);
304 /// evaluate() is the main evaluation function. It always computes two
305 /// values, an endgame score and a middle game score, and interpolates
306 /// between them based on the remaining material.
308 Value evaluate(const Position &pos, EvalInfo &ei, int threadID) {
311 assert(threadID >= 0 && threadID < THREAD_MAX);
313 memset(&ei, 0, sizeof(EvalInfo));
315 // Initialize by reading the incrementally updated scores included in the
316 // position object (material + piece square tables)
317 ei.mgValue = pos.mg_value();
318 ei.egValue = pos.eg_value();
320 // Probe the material hash table
321 ei.mi = MaterialTable[threadID]->get_material_info(pos);
322 ei.mgValue += ei.mi->mg_value();
323 ei.egValue += ei.mi->eg_value();
325 // If we have a specialized evaluation function for the current material
326 // configuration, call it and return
327 if (ei.mi->specialized_eval_exists())
328 return ei.mi->evaluate(pos);
330 // After get_material_info() call that modifies them
331 ScaleFactor factor[2];
332 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
333 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
335 // Probe the pawn hash table
336 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
337 ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
338 ei.egValue += apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame);
340 // Initialize king attack bitboards and king attack zones for both sides
341 ei.attackedBy[WHITE][KING] = pos.piece_attacks<KING>(pos.king_square(WHITE));
342 ei.attackedBy[BLACK][KING] = pos.piece_attacks<KING>(pos.king_square(BLACK));
343 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
344 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
346 // Initialize pawn attack bitboards for both sides
347 ei.attackedBy[WHITE][PAWN] = ((pos.pawns(WHITE) << 9) & ~FileABB) | ((pos.pawns(WHITE) << 7) & ~FileHBB);
348 ei.attackedBy[BLACK][PAWN] = ((pos.pawns(BLACK) >> 7) & ~FileABB) | ((pos.pawns(BLACK) >> 9) & ~FileHBB);
349 ei.kingAttackersCount[WHITE] = count_1s_max_15(ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING])/2;
350 ei.kingAttackersCount[BLACK] = count_1s_max_15(ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING])/2;
353 for (Color c = WHITE; c <= BLACK; c++)
356 for (int i = 0; i < pos.piece_count(c, KNIGHT); i++)
357 evaluate_knight(pos, pos.piece_list(c, KNIGHT, i), c, ei);
360 for (int i = 0; i < pos.piece_count(c, BISHOP); i++)
361 evaluate_bishop(pos, pos.piece_list(c, BISHOP, i), c, ei);
364 for (int i = 0; i < pos.piece_count(c, ROOK); i++)
365 evaluate_rook(pos, pos.piece_list(c, ROOK, i), c, ei);
368 for(int i = 0; i < pos.piece_count(c, QUEEN); i++)
369 evaluate_queen(pos, pos.piece_list(c, QUEEN, i), c, ei);
371 // Special pattern: trapped bishops on a7/h7/a2/h2
372 Bitboard b = pos.bishops(c) & MaskA7H7[c];
375 Square s = pop_1st_bit(&b);
376 evaluate_trapped_bishop_a7h7(pos, s, c, ei);
379 // Special pattern: trapped bishops on a1/h1/a8/h8 in Chess960:
382 b = pos.bishops(c) & MaskA1H1[c];
385 Square s = pop_1st_bit(&b);
386 evaluate_trapped_bishop_a1h1(pos, s, c, ei);
390 // Sum up all attacked squares
391 ei.attackedBy[c][0] = ei.attackedBy[c][PAWN] | ei.attackedBy[c][KNIGHT]
392 | ei.attackedBy[c][BISHOP] | ei.attackedBy[c][ROOK]
393 | ei.attackedBy[c][QUEEN] | ei.attackedBy[c][KING];
396 // Kings. Kings are evaluated after all other pieces for both sides,
397 // because we need complete attack information for all pieces when computing
398 // the king safety evaluation.
399 for (Color c = WHITE; c <= BLACK; c++)
400 evaluate_king(pos, pos.king_square(c), c, ei);
402 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
403 // because we need to know which side promotes first in positions where
404 // both sides have an unstoppable passed pawn.
405 if (ei.pi->passed_pawns())
406 evaluate_passed_pawns(pos, ei);
408 Phase phase = pos.game_phase();
410 // Middle-game specific evaluation terms
411 if (phase > PHASE_ENDGAME)
413 // Pawn storms in positions with opposite castling.
414 if ( square_file(pos.king_square(WHITE)) >= FILE_E
415 && square_file(pos.king_square(BLACK)) <= FILE_D)
417 ei.mgValue += ei.pi->queenside_storm_value(WHITE)
418 - ei.pi->kingside_storm_value(BLACK);
420 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
421 && square_file(pos.king_square(BLACK)) >= FILE_E)
423 ei.mgValue += ei.pi->kingside_storm_value(WHITE)
424 - ei.pi->queenside_storm_value(BLACK);
426 // Evaluate space for both sides
427 if (ei.mi->space_weight() > 0)
429 evaluate_space(pos, WHITE, ei);
430 evaluate_space(pos, BLACK, ei);
435 ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
436 ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
438 // If we don't already have an unusual scale factor, check for opposite
439 // colored bishop endgames, and use a lower scale for those
440 if ( phase < PHASE_MIDGAME
441 && pos.opposite_colored_bishops()
442 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
443 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
447 // Only the two bishops ?
448 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
449 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
451 // Check for KBP vs KB with only a single pawn that is almost
452 // certainly a draw or at least two pawns.
453 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
454 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
457 // Endgame with opposite-colored bishops, but also other pieces. Still
458 // a bit drawish, but not as drawish as with only the two bishops.
459 sf = ScaleFactor(50);
461 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
463 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
467 // Interpolate between the middle game and the endgame score, and
469 Color stm = pos.side_to_move();
471 Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
473 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
477 /// quick_evaluate() does a very approximate evaluation of the current position.
478 /// It currently considers only material and piece square table scores. Perhaps
479 /// we should add scores from the pawn and material hash tables?
481 Value quick_evaluate(const Position &pos) {
486 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
488 Value mgv = pos.mg_value();
489 Value egv = pos.eg_value();
490 Phase ph = pos.game_phase();
491 Color stm = pos.side_to_move();
493 return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
497 /// init_eval() initializes various tables used by the evaluation function.
499 void init_eval(int threads) {
501 assert(threads <= THREAD_MAX);
503 for (int i = 0; i < THREAD_MAX; i++)
508 delete MaterialTable[i];
510 MaterialTable[i] = NULL;
514 PawnTable[i] = new PawnInfoTable(PawnTableSize);
515 if (!MaterialTable[i])
516 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
519 for (Bitboard b = 0ULL; b < 256ULL; b++)
520 BitCount8Bit[b] = count_1s(b);
524 /// quit_eval() releases heap-allocated memory at program termination.
528 for (int i = 0; i < THREAD_MAX; i++)
531 delete MaterialTable[i];
536 /// read_weights() reads evaluation weights from the corresponding UCI
539 void read_weights(Color us) {
541 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
542 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
543 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
544 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
545 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
546 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
548 Color them = opposite_color(us);
550 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
551 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
552 WeightSpace = weight_option("Space", WeightSpaceInternal);
560 // evaluate_common() computes terms common to all pieces attack
562 template<PieceType Piece>
563 int evaluate_common(const Position& p, const Bitboard& b, Color us, EvalInfo& ei, Square s = SQ_NONE) {
565 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
566 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
567 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
568 static const Value* OutpostBonus[] = { 0, 0, KnightOutpostBonus, BishopOutpostBonus, 0, 0 };
570 Color them = opposite_color(us);
572 // Update attack info
573 ei.attackedBy[us][Piece] |= b;
576 if (b & ei.kingZone[us])
578 ei.kingAttackersCount[us]++;
579 ei.kingAttackersWeight[us] += AttackWeight[Piece];
580 Bitboard bb = (b & ei.attackedBy[them][KING]);
582 ei.kingAdjacentZoneAttacksCount[us] += count_1s_max_15(bb);
585 // Remove squares protected by enemy pawns
586 Bitboard bb = (b & ~ei.attackedBy[them][PAWN]);
589 int mob = (Piece != QUEEN ? count_1s_max_15(bb & ~p.pieces_of_color(us))
590 : count_1s(bb & ~p.pieces_of_color(us)));
592 ei.mgMobility += Sign[us] * MgBonus[Piece][mob];
593 ei.egMobility += Sign[us] * EgBonus[Piece][mob];
595 // Bishop and Knight outposts
596 if ( (Piece != BISHOP && Piece != KNIGHT) // compile time condition
597 || !p.square_is_weak(s, them))
600 // Initial bonus based on square
602 v = bonus = OutpostBonus[Piece][relative_square(us, s)];
604 // Increase bonus if supported by pawn, especially if the opponent has
605 // no minor piece which can exchange the outpost piece
606 if (v && (p.pawn_attacks(them, s) & p.pawns(us)))
609 if ( p.piece_count(them, KNIGHT) == 0
610 && (SquaresByColorBB[square_color(s)] & p.bishops(them)) == EmptyBoardBB)
613 ei.mgValue += Sign[us] * bonus;
614 ei.egValue += Sign[us] * bonus;
619 // evaluate_knight() assigns bonuses and penalties to a knight of a given
620 // color on a given square.
622 void evaluate_knight(const Position& p, Square s, Color us, EvalInfo& ei) {
624 // Attacks, mobility and outposts
625 evaluate_common<KNIGHT>(p, p.piece_attacks<KNIGHT>(s), us, ei, s);
629 // evaluate_bishop() assigns bonuses and penalties to a bishop of a given
630 // color on a given square.
632 void evaluate_bishop(const Position& p, Square s, Color us, EvalInfo& ei) {
634 Bitboard b = bishop_attacks_bb(s, p.occupied_squares() & ~p.queens(us));
636 // Attacks, mobility and outposts
637 evaluate_common<BISHOP>(p, b, us, ei, s);
641 // evaluate_rook() assigns bonuses and penalties to a rook of a given
642 // color on a given square.
644 void evaluate_rook(const Position& p, Square s, Color us, EvalInfo& ei) {
646 Bitboard b = rook_attacks_bb(s, p.occupied_squares() & ~p.rooks_and_queens(us));
648 // Attacks and mobility
649 int mob = evaluate_common<ROOK>(p, b, us, ei);
652 Color them = opposite_color(us);
654 if ( relative_rank(us, s) == RANK_7
655 && relative_rank(us, p.king_square(them)) == RANK_8)
657 ei.mgValue += Sign[us] * MidgameRookOn7thBonus;
658 ei.egValue += Sign[us] * EndgameRookOn7thBonus;
661 // Open and half-open files
662 File f = square_file(s);
663 if (ei.pi->file_is_half_open(us, f))
665 if (ei.pi->file_is_half_open(them, f))
667 ei.mgValue += Sign[us] * RookOpenFileBonus;
668 ei.egValue += Sign[us] * RookOpenFileBonus;
672 ei.mgValue += Sign[us] * RookHalfOpenFileBonus;
673 ei.egValue += Sign[us] * RookHalfOpenFileBonus;
677 // Penalize rooks which are trapped inside a king. Penalize more if
678 // king has lost right to castle
679 if (mob > 6 || ei.pi->file_is_half_open(us, f))
682 Square ksq = p.king_square(us);
684 if ( square_file(ksq) >= FILE_E
685 && square_file(s) > square_file(ksq)
686 && (relative_rank(us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
688 // Is there a half-open file between the king and the edge of the board?
689 if (!ei.pi->has_open_file_to_right(us, square_file(ksq)))
690 ei.mgValue -= p.can_castle(us)? Sign[us] * ((TrappedRookPenalty - mob * 16) / 2)
691 : Sign[us] * (TrappedRookPenalty - mob * 16);
693 else if ( square_file(ksq) <= FILE_D
694 && square_file(s) < square_file(ksq)
695 && (relative_rank(us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
697 // Is there a half-open file between the king and the edge of the board?
698 if (!ei.pi->has_open_file_to_left(us, square_file(ksq)))
699 ei.mgValue -= p.can_castle(us)? Sign[us] * ((TrappedRookPenalty - mob * 16) / 2)
700 : Sign[us] * (TrappedRookPenalty - mob * 16);
705 // evaluate_queen() assigns bonuses and penalties to a queen of a given
706 // color on a given square.
708 void evaluate_queen(const Position& p, Square s, Color us, EvalInfo& ei) {
710 // Attacks and mobility
711 evaluate_common<QUEEN>(p, p.piece_attacks<QUEEN>(s), us, ei);
714 Color them = opposite_color(us);
716 if ( relative_rank(us, s) == RANK_7
717 && relative_rank(us, p.king_square(them)) == RANK_8)
719 ei.mgValue += Sign[us] * MidgameQueenOn7thBonus;
720 ei.egValue += Sign[us] * EndgameQueenOn7thBonus;
724 inline Bitboard shiftRowsDown(const Bitboard& b, int num) {
726 return b >> (num << 3);
729 // evaluate_king() assigns bonuses and penalties to a king of a given
730 // color on a given square.
732 void evaluate_king(const Position& p, Square s, Color us, EvalInfo& ei) {
734 int shelter = 0, sign = Sign[us];
737 if (relative_rank(us, s) <= RANK_4)
739 Bitboard pawns = p.pawns(us) & this_and_neighboring_files_bb(s);
740 Rank r = square_rank(s);
741 for (int i = 1; i < 4; i++)
742 shelter += count_1s_8bit(shiftRowsDown(pawns, r+i*sign)) * (128>>i);
744 ei.mgValue += sign * Value(shelter);
747 // King safety. This is quite complicated, and is almost certainly far
748 // from optimally tuned.
749 Color them = opposite_color(us);
751 if ( p.piece_count(them, QUEEN) >= 1
752 && ei.kingAttackersCount[them] >= 2
753 && p.non_pawn_material(them) >= QueenValueMidgame + RookValueMidgame
754 && ei.kingAdjacentZoneAttacksCount[them])
756 // Is it the attackers turn to move?
757 bool sente = (them == p.side_to_move());
759 // Find the attacked squares around the king which has no defenders
760 // apart from the king itself
761 Bitboard undefended =
762 ei.attacked_by(them) & ~ei.attacked_by(us, PAWN)
763 & ~ei.attacked_by(us, KNIGHT) & ~ei.attacked_by(us, BISHOP)
764 & ~ei.attacked_by(us, ROOK) & ~ei.attacked_by(us, QUEEN)
765 & ei.attacked_by(us, KING);
767 Bitboard occ = p.occupied_squares(), b, b2;
769 // Initialize the 'attackUnits' variable, which is used later on as an
770 // index to the SafetyTable[] array. The initial value is based on the
771 // number and types of the attacking pieces, the number of attacked and
772 // undefended squares around the king, the square of the king, and the
773 // quality of the pawn shelter.
775 Min((ei.kingAttackersCount[them] * ei.kingAttackersWeight[them]) / 2, 25)
776 + (ei.kingAdjacentZoneAttacksCount[them] + count_1s_max_15(undefended)) * 3
777 + InitKingDanger[relative_square(us, s)] - (shelter >> 5);
779 // Analyse safe queen contact checks
780 b = undefended & ei.attacked_by(them, QUEEN) & ~p.pieces_of_color(them);
783 Bitboard attackedByOthers =
784 ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
785 | ei.attacked_by(them, BISHOP) | ei.attacked_by(them, ROOK);
787 b &= attackedByOthers;
790 // The bitboard b now contains the squares available for safe queen
792 int count = count_1s_max_15(b);
793 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
795 // Is there a mate threat?
796 if (QueenContactMates && !p.is_check())
798 Bitboard escapeSquares =
799 p.piece_attacks<KING>(s) & ~p.pieces_of_color(us) & ~attackedByOthers;
803 Square from, to = pop_1st_bit(&b);
804 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
806 // We have a mate, unless the queen is pinned or there
807 // is an X-ray attack through the queen.
808 for (int i = 0; i < p.piece_count(them, QUEEN); i++)
810 from = p.piece_list(them, QUEEN, i);
811 if ( bit_is_set(p.piece_attacks<QUEEN>(from), to)
812 && !bit_is_set(p.pinned_pieces(them), from)
813 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & p.rooks_and_queens(us))
814 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & p.rooks_and_queens(us)))
816 ei.mateThreat[them] = make_move(from, to);
824 // Analyse safe distance checks
825 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
827 b = p.piece_attacks<ROOK>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
830 b2 = b & ei.attacked_by(them, QUEEN);
832 attackUnits += QueenCheckBonus * count_1s_max_15(b2);
835 b2 = b & ei.attacked_by(them, ROOK);
837 attackUnits += RookCheckBonus * count_1s_max_15(b2);
839 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
841 b = p.piece_attacks<BISHOP>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
844 b2 = b & ei.attacked_by(them, QUEEN);
846 attackUnits += QueenCheckBonus * count_1s_max_15(b2);
849 b2 = b & ei.attacked_by(them, BISHOP);
851 attackUnits += BishopCheckBonus * count_1s_max_15(b2);
853 if (KnightCheckBonus > 0)
855 b = p.piece_attacks<KNIGHT>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
858 b2 = b & ei.attacked_by(them, KNIGHT);
860 attackUnits += KnightCheckBonus * count_1s_max_15(b2);
863 // Analyse discovered checks (only for non-pawns right now, consider
864 // adding pawns later).
865 if (DiscoveredCheckBonus)
867 b = p.discovered_check_candidates(them) & ~p.pawns();
869 attackUnits += DiscoveredCheckBonus * count_1s_max_15(b) * (sente? 2 : 1);
872 // Has a mate threat been found? We don't do anything here if the
873 // side with the mating move is the side to move, because in that
874 // case the mating side will get a huge bonus at the end of the main
875 // evaluation function instead.
876 if (ei.mateThreat[them] != MOVE_NONE)
877 attackUnits += MateThreatBonus;
879 // Ensure that attackUnits is between 0 and 99, in order to avoid array
880 // out of bounds errors:
884 if (attackUnits >= 100)
887 // Finally, extract the king safety score from the SafetyTable[] array.
888 // Add the score to the evaluation, and also to ei.futilityMargin. The
889 // reason for adding the king safety score to the futility margin is
890 // that the king safety scores can sometimes be very big, and that
891 // capturing a single attacking piece can therefore result in a score
892 // change far bigger than the value of the captured piece.
893 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[us]);
895 ei.mgValue -= sign * v;
897 if (us == p.side_to_move())
898 ei.futilityMargin += v;
903 // evaluate_passed_pawns() evaluates the passed pawns for both sides.
905 void evaluate_passed_pawns(const Position &pos, EvalInfo &ei) {
907 bool hasUnstoppable[2] = {false, false};
908 int movesToGo[2] = {100, 100};
910 for (Color us = WHITE; us <= BLACK; us++)
912 Color them = opposite_color(us);
913 Square ourKingSq = pos.king_square(us);
914 Square theirKingSq = pos.king_square(them);
915 Bitboard b = ei.pi->passed_pawns() & pos.pawns(us), b2, b3, b4;
919 Square s = pop_1st_bit(&b);
921 assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN));
922 assert(pos.pawn_is_passed(us, s));
924 int r = int(relative_rank(us, s) - RANK_2);
925 int tr = Max(0, r * (r - 1));
926 Square blockSq = s + pawn_push(us);
928 // Base bonus based on rank
929 Value mbonus = Value(20 * tr);
930 Value ebonus = Value(10 + r * r * 10);
932 // Adjust bonus based on king proximity
935 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
936 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(us)) * 1 * tr);
937 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
939 // If the pawn is free to advance, increase bonus
940 if (pos.square_is_empty(blockSq))
942 b2 = squares_in_front_of(us, s);
943 b3 = b2 & ei.attacked_by(them);
944 b4 = b2 & ei.attacked_by(us);
946 // If there is an enemy rook or queen attacking the pawn from behind,
947 // add all X-ray attacks by the rook or queen.
948 if ( bit_is_set(ei.attacked_by(them,ROOK) | ei.attacked_by(them,QUEEN),s)
949 && (squares_behind(us, s) & pos.rooks_and_queens(them)))
952 if ((b2 & pos.pieces_of_color(them)) == EmptyBoardBB)
954 // There are no enemy pieces in the pawn's path! Are any of the
955 // squares in the pawn's path attacked by the enemy?
956 if (b3 == EmptyBoardBB)
957 // No enemy attacks, huge bonus!
958 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
960 // OK, there are enemy attacks. Are those squares which are
961 // attacked by the enemy also attacked by us? If yes, big bonus
962 // (but smaller than when there are no enemy attacks), if no,
963 // somewhat smaller bonus.
964 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
968 // There are some enemy pieces in the pawn's path. While this is
969 // sad, we still assign a moderate bonus if all squares in the path
970 // which are either occupied by or attacked by enemy pieces are
971 // also attacked by us.
972 if (((b3 | (b2 & pos.pieces_of_color(them))) & ~b4) == EmptyBoardBB)
973 ebonus += Value(tr * 6);
975 // At last, add a small bonus when there are no *friendly* pieces
976 // in the pawn's path.
977 if ((b2 & pos.pieces_of_color(us)) == EmptyBoardBB)
982 // If the pawn is supported by a friendly pawn, increase bonus
983 b2 = pos.pawns(us) & neighboring_files_bb(s);
985 ebonus += Value(r * 20);
986 else if (pos.pawn_attacks(them, s) & b2)
987 ebonus += Value(r * 12);
989 // If the other side has only a king, check whether the pawn is
991 if (pos.non_pawn_material(them) == Value(0))
996 qsq = relative_square(us, make_square(square_file(s), RANK_8));
997 d = square_distance(s, qsq)
998 - square_distance(theirKingSq, qsq)
999 + (us != pos.side_to_move());
1003 int mtg = RANK_8 - relative_rank(us, s);
1004 int blockerCount = count_1s_max_15(squares_in_front_of(us,s) & pos.occupied_squares());
1005 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)
1022 if( pos.non_pawn_material(them) <= KnightValueMidgame
1023 && pos.piece_count(them, KNIGHT) <= 1)
1024 ebonus += ebonus / 4;
1025 else if(pos.rooks_and_queens(them))
1026 ebonus -= ebonus / 4;
1029 // Add the scores for this pawn to the middle game and endgame eval.
1030 ei.mgValue += apply_weight(Sign[us] * mbonus, WeightPassedPawnsMidgame);
1031 ei.egValue += apply_weight(Sign[us] * ebonus, WeightPassedPawnsEndgame);
1035 // Does either side have an unstoppable passed pawn?
1036 if (hasUnstoppable[WHITE] && !hasUnstoppable[BLACK])
1037 ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]);
1038 else if (hasUnstoppable[BLACK] && !hasUnstoppable[WHITE])
1039 ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]);
1040 else if (hasUnstoppable[BLACK] && hasUnstoppable[WHITE])
1042 // Both sides have unstoppable pawns! Try to find out who queens
1043 // first. We begin by transforming 'movesToGo' to the number of
1044 // plies until the pawn queens for both sides.
1045 movesToGo[WHITE] *= 2;
1046 movesToGo[BLACK] *= 2;
1047 movesToGo[pos.side_to_move()]--;
1049 // If one side queens at least three plies before the other, that
1051 if (movesToGo[WHITE] <= movesToGo[BLACK] - 3)
1052 ei.egValue += UnstoppablePawnValue - Value(0x40 * (movesToGo[WHITE]/2));
1053 else if(movesToGo[BLACK] <= movesToGo[WHITE] - 3)
1054 ei.egValue -= UnstoppablePawnValue - Value(0x40 * (movesToGo[BLACK]/2));
1056 // We could also add some rules about the situation when one side
1057 // queens exactly one ply before the other: Does the first queen
1058 // check the opponent's king, or attack the opponent's queening square?
1059 // This is slightly tricky to get right, because it is possible that
1060 // the opponent's king has moved somewhere before the first pawn queens.
1065 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1066 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1069 void evaluate_trapped_bishop_a7h7(const Position &pos, Square s, Color us,
1071 assert(square_is_ok(s));
1072 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1074 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1075 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1077 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1078 && pos.see(s, b6) < 0
1079 && pos.see(s, b8) < 0)
1081 ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
1082 ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
1087 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1088 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1089 // black), and assigns a penalty if it is. This pattern can obviously
1090 // only occur in Chess960 games.
1092 void evaluate_trapped_bishop_a1h1(const Position &pos, Square s, Color us,
1094 Piece pawn = piece_of_color_and_type(us, PAWN);
1098 assert(square_is_ok(s));
1099 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1101 if (square_file(s) == FILE_A)
1103 b2 = relative_square(us, SQ_B2);
1104 b3 = relative_square(us, SQ_B3);
1105 c3 = relative_square(us, SQ_C3);
1109 b2 = relative_square(us, SQ_G2);
1110 b3 = relative_square(us, SQ_G3);
1111 c3 = relative_square(us, SQ_F3);
1114 if (pos.piece_on(b2) == pawn)
1118 if (!pos.square_is_empty(b3))
1119 penalty = 2*TrappedBishopA1H1Penalty;
1120 else if (pos.piece_on(c3) == pawn)
1121 penalty = TrappedBishopA1H1Penalty;
1123 penalty = TrappedBishopA1H1Penalty / 2;
1125 ei.mgValue -= Sign[us] * penalty;
1126 ei.egValue -= Sign[us] * penalty;
1131 // evaluate_space() computes the space evaluation for a given side. The
1132 // space evaluation is a simple bonus based on the number of safe squares
1133 // available for minor pieces on the central four files on ranks 2--4. Safe
1134 // squares one, two or three squares behind a friendly pawn are counted
1135 // twice. Finally, the space bonus is scaled by a weight taken from the
1136 // material hash table.
1138 void evaluate_space(const Position &pos, Color us, EvalInfo &ei) {
1140 Color them = opposite_color(us);
1142 // Find the safe squares for our pieces inside the area defined by
1143 // SpaceMask[us]. A square is unsafe it is attacked by an enemy
1144 // pawn, or if it is undefended and attacked by an enemy piece.
1146 Bitboard safeSquares = SpaceMask[us]
1148 & ~ei.attacked_by(them, PAWN)
1149 & ~(~ei.attacked_by(us) & ei.attacked_by(them));
1151 // Find all squares which are at most three squares behind some friendly
1153 Bitboard behindFriendlyPawns = pos.pawns(us);
1156 behindFriendlyPawns |= (behindFriendlyPawns >> 8);
1157 behindFriendlyPawns |= (behindFriendlyPawns >> 16);
1161 behindFriendlyPawns |= (behindFriendlyPawns << 8);
1162 behindFriendlyPawns |= (behindFriendlyPawns << 16);
1165 int space = count_1s_max_15(safeSquares)
1166 + count_1s_max_15(behindFriendlyPawns & safeSquares);
1168 ei.mgValue += Sign[us] * apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
1172 // apply_weight() applies an evaluation weight to a value
1174 inline Value apply_weight(Value v, int w) {
1175 return (v*w) / 0x100;
1179 // scale_by_game_phase() interpolates between a middle game and an endgame
1180 // score, based on game phase. It also scales the return value by a
1181 // ScaleFactor array.
1183 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
1185 assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
1186 assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
1187 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1189 ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
1191 Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
1192 return Value(int(result) & ~(GrainSize - 1));
1196 // count_1s_8bit() counts the number of nonzero bits in the 8 least
1197 // significant bits of a Bitboard. This function is used by the king
1198 // shield evaluation.
1200 int count_1s_8bit(Bitboard b) {
1201 return int(BitCount8Bit[b & 0xFF]);
1205 // compute_weight() computes the value of an evaluation weight, by combining
1206 // an UCI-configurable weight with an internal weight.
1208 int compute_weight(int uciWeight, int internalWeight) {
1210 uciWeight = (uciWeight * 0x100) / 100;
1211 return (uciWeight * internalWeight) / 0x100;
1215 // helper used in read_weights()
1216 int weight_option(const std::string& opt, int weight) {
1218 return compute_weight(get_option_value_int(opt), weight);
1222 // init_safety() initizes the king safety evaluation, based on UCI
1223 // parameters. It is called from read_weights().
1225 void init_safety() {
1227 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1228 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1229 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1230 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1231 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1232 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1233 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1235 int maxSlope = get_option_value_int("King Safety Max Slope");
1236 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1237 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1238 double b = get_option_value_int("King Safety X Intercept");
1239 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1240 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1242 for (int i = 0; i < 100; i++)
1245 SafetyTable[i] = Value(0);
1247 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1249 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1252 for (int i = 0; i < 100; i++)
1254 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1255 for (int j = i + 1; j < 100; j++)
1256 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1258 if (SafetyTable[i] > Value(peak))
1259 SafetyTable[i] = Value(peak);