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 = 4;
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
76 // Knight mobility bonus in middle game and endgame, indexed by the number
77 // of attacked squares not occupied by friendly piecess.
78 const Value MidgameKnightMobilityBonus[] = {
80 V(-38), V(-25),V(-12), V(0), V(12), V(25), V(31), V(38), V(38)
83 const Value EndgameKnightMobilityBonus[] = {
85 V(-33), V(-23),V(-13), V(-3), V(7), V(17), V(22), V(27), V(27)
88 // Bishop mobility bonus in middle game and endgame, indexed by the number
89 // of attacked squares not occupied by friendly pieces. X-ray attacks through
90 // queens are also included.
91 const Value MidgameBishopMobilityBonus[] = {
93 V(-25), V(-11), V(3), V(17), V(31), V(45), V(57), V(65),
94 // 8 9 10 11 12 13 14 15
95 V( 71), V( 74), V(76), V(78), V(79), V(80), V(81), V(81)
98 const Value EndgameBishopMobilityBonus[] = {
100 V(-30), V(-16), V(-2), V(12), V(26), V(40), V(52), V(60),
101 // 8 9 10 11 12 13 14 15
102 V( 65), V( 69), V(71), V(73), V(74), V(75), V(76), V(76)
105 // Rook mobility bonus in middle game and endgame, indexed by the number
106 // of attacked squares not occupied by friendly pieces. X-ray attacks through
107 // queens and rooks are also included.
108 const Value MidgameRookMobilityBonus[] = {
110 V(-20), V(-14), V(-8), V(-2), V(4), V(10), V(14), V(19),
111 // 8 9 10 11 12 13 14 15
112 V( 23), V( 26), V(27), V(28), V(29), V(30), V(31), V(32)
115 const Value EndgameRookMobilityBonus[] = {
117 V(-36), V(-19), V(-3), V(13), V(29), V(46), V(62), V(79),
118 // 8 9 10 11 12 13 14 15
119 V( 95), V(106),V(111),V(114),V(116),V(117),V(118),V(118)
122 // Queen mobility bonus in middle game and endgame, indexed by the number
123 // of attacked squares not occupied by friendly pieces.
124 const Value MidgameQueenMobilityBonus[] = {
126 V(-10), V(-8), V(-6), V(-3), V(-1), V( 1), V( 3), V( 5),
127 // 8 9 10 11 12 13 14 15
128 V( 8), V(10), V(12), V(15), V(16), V(17), V(18), V(20),
129 // 16 17 18 19 20 21 22 23
130 V( 20), V(20), V(20), V(20), V(20), V(20), V(20), V(20),
131 // 24 25 26 27 28 29 30 31
132 V( 20), V(20), V(20), V(20), V(20), V(20), V(20), V(20)
135 const Value EndgameQueenMobilityBonus[] = {
137 V(-18),V(-13), V(-7), V(-2), V( 3), V (8), V(13), V(19),
138 // 8 9 10 11 12 13 14 15
139 V( 23), V(27), V(32), V(34), V(35), V(35), V(35), V(35),
140 // 16 17 18 19 20 21 22 23
141 V( 35), V(35), V(35), V(35), V(35), V(35), V(35), V(35),
142 // 24 25 26 27 28 29 30 31
143 V( 35), V(35), V(35), V(35), V(35), V(35), V(35), V(35)
146 // Outpost bonuses for knights and bishops, indexed by square (from white's
148 const Value KnightOutpostBonus[64] = {
150 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
151 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
152 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0), // 3
153 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0), // 4
154 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0), // 5
155 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0), // 6
156 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
157 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
160 const Value BishopOutpostBonus[64] = {
162 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 1
163 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 2
164 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0), // 3
165 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0), // 4
166 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0), // 5
167 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0), // 6
168 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // 7
169 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
172 // Bonus for unstoppable passed pawns
173 const Value UnstoppablePawnValue = Value(0x500);
175 // Rooks and queens on the 7th rank (modified by Joona Kiiski)
176 const Value MidgameRookOn7thBonus = Value(47);
177 const Value EndgameRookOn7thBonus = Value(98);
178 const Value MidgameQueenOn7thBonus = Value(27);
179 const Value EndgameQueenOn7thBonus = Value(54);
181 // Rooks on open files (modified by Joona Kiiski)
182 const Value RookOpenFileBonus = Value(43);
183 const Value RookHalfOpenFileBonus = Value(19);
185 // Penalty for rooks trapped inside a friendly king which has lost the
187 const Value TrappedRookPenalty = Value(180);
189 // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
191 const Value TrappedBishopA7H7Penalty = Value(300);
193 // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
194 const Bitboard MaskA7H7[2] = {
195 ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
196 ((1ULL << SQ_A2) | (1ULL << SQ_H2))
199 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
200 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
201 // happen in Chess960 games.
202 const Value TrappedBishopA1H1Penalty = Value(100);
204 // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
205 const Bitboard MaskA1H1[2] = {
206 ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
207 ((1ULL << SQ_A8) | (1ULL << SQ_H8))
210 // The SpaceMask[color] contains area of the board which is consdered by
211 // the space evaluation. In the middle game, each side is given a bonus
212 // based on how many squares inside this area are safe and available for
213 // friendly minor pieces.
214 const Bitboard SpaceMask[2] = {
215 (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
216 (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
217 (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
218 (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
219 (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
220 (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
223 /// King safety constants and variables. The king safety scores are taken
224 /// from the array SafetyTable[]. Various little "meta-bonuses" measuring
225 /// the strength of the attack are added up into an integer, which is used
226 /// as an index to SafetyTable[].
228 // Attack weights for each piece type
229 const int QueenAttackWeight = 5;
230 const int RookAttackWeight = 3;
231 const int BishopAttackWeight = 2;
232 const int KnightAttackWeight = 2;
234 // Bonuses for safe checks, initialized from UCI options
235 int QueenContactCheckBonus, DiscoveredCheckBonus;
236 int QueenCheckBonus, RookCheckBonus, BishopCheckBonus, KnightCheckBonus;
238 // Scan for queen contact mates?
239 const bool QueenContactMates = true;
241 // Bonus for having a mate threat, initialized from UCI options
244 // InitKingDanger[] contains bonuses based on the position of the defending
246 const int InitKingDanger[64] = {
247 2, 0, 2, 5, 5, 2, 0, 2,
248 2, 2, 4, 8, 8, 4, 2, 2,
249 7, 10, 12, 12, 12, 12, 10, 7,
250 15, 15, 15, 15, 15, 15, 15, 15,
251 15, 15, 15, 15, 15, 15, 15, 15,
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
257 // SafetyTable[] contains the actual king safety scores. It is initialized
259 Value SafetyTable[100];
261 // Pawn and material hash tables, indexed by the current thread id
262 PawnInfoTable* PawnTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
263 MaterialInfoTable* MaterialTable[8] = {0, 0, 0, 0, 0, 0, 0, 0};
265 // Sizes of pawn and material hash tables
266 const int PawnTableSize = 16384;
267 const int MaterialTableSize = 1024;
269 // Array which gives the number of nonzero bits in an 8-bit integer
270 uint8_t BitCount8Bit[256];
272 // Function prototypes
273 template<bool HasPopCnt>
274 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID);
276 template<PieceType Piece, bool HasPopCnt>
277 void evaluate_pieces(const Position& p, Color us, EvalInfo& ei);
279 template<bool HasPopCnt>
280 void evaluate_king(const Position& p, 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,
287 template<bool HasPopCnt>
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 compute_weight(int uciWeight, int internalWeight);
293 int weight_option(const std::string& opt, int weight);
303 /// evaluate() is the main evaluation function. It always computes two
304 /// values, an endgame score and a middle game score, and interpolates
305 /// between them based on the remaining material.
306 Value evaluate(const Position& pos, EvalInfo& ei, int threadID) {
308 return CpuHasPOPCNT ? do_evaluate<true>(pos, ei, threadID)
309 : do_evaluate<false>(pos, ei, threadID);
314 template<bool HasPopCnt>
315 Value do_evaluate(const Position& pos, EvalInfo& ei, int threadID) {
318 assert(threadID >= 0 && threadID < THREAD_MAX);
320 memset(&ei, 0, sizeof(EvalInfo));
322 // Initialize by reading the incrementally updated scores included in the
323 // position object (material + piece square tables)
324 ei.mgValue = pos.mg_value();
325 ei.egValue = pos.eg_value();
327 // Probe the material hash table
328 ei.mi = MaterialTable[threadID]->get_material_info(pos);
329 ei.mgValue += ei.mi->material_value();
330 ei.egValue += ei.mi->material_value();
332 // If we have a specialized evaluation function for the current material
333 // configuration, call it and return
334 if (ei.mi->specialized_eval_exists())
335 return ei.mi->evaluate(pos);
337 // After get_material_info() call that modifies them
338 ScaleFactor factor[2];
339 factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
340 factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
342 // Probe the pawn hash table
343 ei.pi = PawnTable[threadID]->get_pawn_info(pos);
344 ei.mgValue += apply_weight(ei.pi->mg_value(), WeightPawnStructureMidgame);
345 ei.egValue += apply_weight(ei.pi->eg_value(), WeightPawnStructureEndgame);
347 // Initialize king attack bitboards and king attack zones for both sides
348 ei.attackedBy[WHITE][KING] = pos.piece_attacks<KING>(pos.king_square(WHITE));
349 ei.attackedBy[BLACK][KING] = pos.piece_attacks<KING>(pos.king_square(BLACK));
350 ei.kingZone[WHITE] = ei.attackedBy[BLACK][KING] | (ei.attackedBy[BLACK][KING] >> 8);
351 ei.kingZone[BLACK] = ei.attackedBy[WHITE][KING] | (ei.attackedBy[WHITE][KING] << 8);
353 // Initialize pawn attack bitboards for both sides
354 ei.attackedBy[WHITE][PAWN] = ((pos.pawns(WHITE) << 9) & ~FileABB) | ((pos.pawns(WHITE) << 7) & ~FileHBB);
355 ei.attackedBy[BLACK][PAWN] = ((pos.pawns(BLACK) >> 7) & ~FileABB) | ((pos.pawns(BLACK) >> 9) & ~FileHBB);
356 ei.kingAttackersCount[WHITE] = count_1s_max_15<HasPopCnt>(ei.attackedBy[WHITE][PAWN] & ei.attackedBy[BLACK][KING])/2;
357 ei.kingAttackersCount[BLACK] = count_1s_max_15<HasPopCnt>(ei.attackedBy[BLACK][PAWN] & ei.attackedBy[WHITE][KING])/2;
360 for (Color c = WHITE; c <= BLACK; c++)
362 evaluate_pieces<KNIGHT, HasPopCnt>(pos, c, ei);
363 evaluate_pieces<BISHOP, HasPopCnt>(pos, c, ei);
364 evaluate_pieces<ROOK, HasPopCnt>(pos, c, ei);
365 evaluate_pieces<QUEEN, HasPopCnt>(pos, c, ei);
367 // Sum up all attacked squares
368 ei.attackedBy[c][0] = ei.attackedBy[c][PAWN] | ei.attackedBy[c][KNIGHT]
369 | ei.attackedBy[c][BISHOP] | ei.attackedBy[c][ROOK]
370 | ei.attackedBy[c][QUEEN] | ei.attackedBy[c][KING];
373 // Kings. Kings are evaluated after all other pieces for both sides,
374 // because we need complete attack information for all pieces when computing
375 // the king safety evaluation.
376 for (Color c = WHITE; c <= BLACK; c++)
377 evaluate_king<HasPopCnt>(pos, c, ei);
379 // Evaluate passed pawns. We evaluate passed pawns for both sides at once,
380 // because we need to know which side promotes first in positions where
381 // both sides have an unstoppable passed pawn.
382 if (ei.pi->passed_pawns())
383 evaluate_passed_pawns(pos, ei);
385 Phase phase = pos.game_phase();
387 // Middle-game specific evaluation terms
388 if (phase > PHASE_ENDGAME)
390 // Pawn storms in positions with opposite castling.
391 if ( square_file(pos.king_square(WHITE)) >= FILE_E
392 && square_file(pos.king_square(BLACK)) <= FILE_D)
394 ei.mgValue += ei.pi->queenside_storm_value(WHITE)
395 - ei.pi->kingside_storm_value(BLACK);
397 else if ( square_file(pos.king_square(WHITE)) <= FILE_D
398 && square_file(pos.king_square(BLACK)) >= FILE_E)
400 ei.mgValue += ei.pi->kingside_storm_value(WHITE)
401 - ei.pi->queenside_storm_value(BLACK);
403 // Evaluate space for both sides
404 if (ei.mi->space_weight() > 0)
406 evaluate_space<HasPopCnt>(pos, WHITE, ei);
407 evaluate_space<HasPopCnt>(pos, BLACK, ei);
412 ei.mgValue += apply_weight(ei.mgMobility, WeightMobilityMidgame);
413 ei.egValue += apply_weight(ei.egMobility, WeightMobilityEndgame);
415 // If we don't already have an unusual scale factor, check for opposite
416 // colored bishop endgames, and use a lower scale for those
417 if ( phase < PHASE_MIDGAME
418 && pos.opposite_colored_bishops()
419 && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && ei.egValue > Value(0))
420 || (factor[BLACK] == SCALE_FACTOR_NORMAL && ei.egValue < Value(0))))
424 // Only the two bishops ?
425 if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
426 && pos.non_pawn_material(BLACK) == BishopValueMidgame)
428 // Check for KBP vs KB with only a single pawn that is almost
429 // certainly a draw or at least two pawns.
430 bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
431 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
434 // Endgame with opposite-colored bishops, but also other pieces. Still
435 // a bit drawish, but not as drawish as with only the two bishops.
436 sf = ScaleFactor(50);
438 if (factor[WHITE] == SCALE_FACTOR_NORMAL)
440 if (factor[BLACK] == SCALE_FACTOR_NORMAL)
444 // Interpolate between the middle game and the endgame score, and
446 Color stm = pos.side_to_move();
448 Value v = Sign[stm] * scale_by_game_phase(ei.mgValue, ei.egValue, phase, factor);
450 return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
455 /// quick_evaluate() does a very approximate evaluation of the current position.
456 /// It currently considers only material and piece square table scores. Perhaps
457 /// we should add scores from the pawn and material hash tables?
459 Value quick_evaluate(const Position &pos) {
464 ScaleFactor sf[2] = {SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL};
466 Value mgv = pos.mg_value();
467 Value egv = pos.eg_value();
468 Phase ph = pos.game_phase();
469 Color stm = pos.side_to_move();
471 return Sign[stm] * scale_by_game_phase(mgv, egv, ph, sf);
475 /// init_eval() initializes various tables used by the evaluation function.
477 void init_eval(int threads) {
479 assert(threads <= THREAD_MAX);
481 for (int i = 0; i < THREAD_MAX; i++)
486 delete MaterialTable[i];
488 MaterialTable[i] = NULL;
492 PawnTable[i] = new PawnInfoTable(PawnTableSize);
493 if (!MaterialTable[i])
494 MaterialTable[i] = new MaterialInfoTable(MaterialTableSize);
497 for (Bitboard b = 0ULL; b < 256ULL; b++)
499 assert(count_1s(b) == int(uint8_t(count_1s(b))));
500 BitCount8Bit[b] = (uint8_t)count_1s(b);
505 /// quit_eval() releases heap-allocated memory at program termination.
509 for (int i = 0; i < THREAD_MAX; i++)
512 delete MaterialTable[i];
514 MaterialTable[i] = NULL;
519 /// read_weights() reads evaluation weights from the corresponding UCI
522 void read_weights(Color us) {
524 WeightMobilityMidgame = weight_option("Mobility (Middle Game)", WeightMobilityMidgameInternal);
525 WeightMobilityEndgame = weight_option("Mobility (Endgame)", WeightMobilityEndgameInternal);
526 WeightPawnStructureMidgame = weight_option("Pawn Structure (Middle Game)", WeightPawnStructureMidgameInternal);
527 WeightPawnStructureEndgame = weight_option("Pawn Structure (Endgame)", WeightPawnStructureEndgameInternal);
528 WeightPassedPawnsMidgame = weight_option("Passed Pawns (Middle Game)", WeightPassedPawnsMidgameInternal);
529 WeightPassedPawnsEndgame = weight_option("Passed Pawns (Endgame)", WeightPassedPawnsEndgameInternal);
531 Color them = opposite_color(us);
533 WeightKingSafety[us] = weight_option("Cowardice", WeightKingSafetyInternal);
534 WeightKingSafety[them] = weight_option("Aggressiveness", WeightKingOppSafetyInternal);
535 // If running in analysis mode, make sure we use symmetrical king safety.
536 // We do this by replacing both WeightKingSafety[us] and
537 // WeightKingSafety[them] by their average.
538 if (get_option_value_bool("UCI_AnalyseMode")) {
539 WeightKingSafety[us] = (WeightKingSafety[us] + WeightKingSafety[them]) / 2;
540 WeightKingSafety[them] = WeightKingSafety[us];
543 WeightSpace = weight_option("Space", WeightSpaceInternal);
551 // evaluate_mobility() computes mobility and attacks for every piece
553 template<PieceType Piece, bool HasPopCnt>
554 int evaluate_mobility(const Position& p, const Bitboard& b, Color us, Color them, EvalInfo& ei) {
556 static const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
557 static const Value* MgBonus[] = { 0, 0, MidgameKnightMobilityBonus, MidgameBishopMobilityBonus, MidgameRookMobilityBonus, MidgameQueenMobilityBonus };
558 static const Value* EgBonus[] = { 0, 0, EndgameKnightMobilityBonus, EndgameBishopMobilityBonus, EndgameRookMobilityBonus, EndgameQueenMobilityBonus };
560 // Update attack info
561 ei.attackedBy[us][Piece] |= b;
564 if (b & ei.kingZone[us])
566 ei.kingAttackersCount[us]++;
567 ei.kingAttackersWeight[us] += AttackWeight[Piece];
568 Bitboard bb = (b & ei.attackedBy[them][KING]);
570 ei.kingAdjacentZoneAttacksCount[us] += count_1s_max_15<HasPopCnt>(bb);
573 // Remove squares protected by enemy pawns
574 Bitboard bb = (b & ~ei.attackedBy[them][PAWN]);
577 int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(bb & ~p.pieces_of_color(us))
578 : count_1s<HasPopCnt>(bb & ~p.pieces_of_color(us)));
580 ei.mgMobility += Sign[us] * MgBonus[Piece][mob];
581 ei.egMobility += Sign[us] * EgBonus[Piece][mob];
586 // evaluate_outposts() evaluates bishop and knight outposts squares
588 template<PieceType Piece>
589 void evaluate_outposts(const Position& p, Color us, Color them, EvalInfo& ei, Square s) {
591 // Initial bonus based on square
592 Value bonus = (Piece == BISHOP ? BishopOutpostBonus[relative_square(us, s)]
593 : KnightOutpostBonus[relative_square(us, s)]);
595 // Increase bonus if supported by pawn, especially if the opponent has
596 // no minor piece which can exchange the outpost piece
597 if (bonus && (p.pawn_attacks(them, s) & p.pawns(us)))
599 if ( p.knights(them) == EmptyBoardBB
600 && (SquaresByColorBB[square_color(s)] & p.bishops(them)) == EmptyBoardBB)
601 bonus += bonus + bonus / 2;
605 ei.mgValue += Sign[us] * bonus;
606 ei.egValue += Sign[us] * bonus;
610 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given
613 template<PieceType Piece, bool HasPopCnt>
614 void evaluate_pieces(const Position& pos, Color us, EvalInfo& ei) {
620 Color them = opposite_color(us);
622 for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
624 s = pos.piece_list(us, Piece, i);
626 if (Piece == KNIGHT || Piece == QUEEN)
627 b = pos.piece_attacks<Piece>(s);
628 else if (Piece == BISHOP)
629 b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.queens(us));
630 else if (Piece == ROOK)
631 b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.rooks_and_queens(us));
635 // Attacks and mobility
636 mob = evaluate_mobility<Piece, HasPopCnt>(pos, b, us, them, ei);
638 // Bishop and knight outposts squares
639 if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, them))
640 evaluate_outposts<Piece>(pos, us, them, ei, s);
642 // Special patterns: trapped bishops on a7/h7/a2/h2
643 // and trapped bishops on a1/h1/a8/h8 in Chess960.
646 if (bit_is_set(MaskA7H7[us], s))
647 evaluate_trapped_bishop_a7h7(pos, s, us, ei);
649 if (Chess960 && bit_is_set(MaskA1H1[us], s))
650 evaluate_trapped_bishop_a1h1(pos, s, us, ei);
653 if (Piece == ROOK || Piece == QUEEN)
655 // Queen or rook on 7th rank
656 if ( relative_rank(us, s) == RANK_7
657 && relative_rank(us, pos.king_square(them)) == RANK_8)
659 ei.mgValue += Sign[us] * (Piece == ROOK ? MidgameRookOn7thBonus : MidgameQueenOn7thBonus);
660 ei.egValue += Sign[us] * (Piece == ROOK ? EndgameRookOn7thBonus : EndgameQueenOn7thBonus);
664 // Special extra evaluation for rooks
667 // Open and half-open files
669 if (ei.pi->file_is_half_open(us, f))
671 if (ei.pi->file_is_half_open(them, f))
673 ei.mgValue += Sign[us] * RookOpenFileBonus;
674 ei.egValue += Sign[us] * RookOpenFileBonus;
678 ei.mgValue += Sign[us] * RookHalfOpenFileBonus;
679 ei.egValue += Sign[us] * RookHalfOpenFileBonus;
683 // Penalize rooks which are trapped inside a king. Penalize more if
684 // king has lost right to castle.
685 if (mob > 6 || ei.pi->file_is_half_open(us, f))
688 ksq = pos.king_square(us);
690 if ( square_file(ksq) >= FILE_E
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_right(us, square_file(ksq)))
696 ei.mgValue -= pos.can_castle(us)? Sign[us] * ((TrappedRookPenalty - mob * 16) / 2)
697 : Sign[us] * (TrappedRookPenalty - mob * 16);
699 else if ( square_file(ksq) <= FILE_D
700 && square_file(s) < square_file(ksq)
701 && (relative_rank(us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
703 // Is there a half-open file between the king and the edge of the board?
704 if (!ei.pi->has_open_file_to_left(us, square_file(ksq)))
705 ei.mgValue -= pos.can_castle(us)? Sign[us] * ((TrappedRookPenalty - mob * 16) / 2)
706 : Sign[us] * (TrappedRookPenalty - mob * 16);
712 inline Bitboard shiftRowsDown(const Bitboard& b, int num) {
714 return b >> (num << 3);
717 // evaluate_king<>() assigns bonuses and penalties to a king of a given color.
719 template<bool HasPopCnt>
720 void evaluate_king(const Position& p, Color us, EvalInfo& ei) {
722 int shelter = 0, sign = Sign[us];
723 Square s = p.king_square(us);
726 if (relative_rank(us, s) <= RANK_4)
728 // Shelter cache lookup
729 shelter = ei.pi->kingShelter(us, s);
733 Bitboard pawns = p.pawns(us) & this_and_neighboring_files_bb(s);
734 Rank r = square_rank(s);
735 for (int i = 1; i < 4; i++)
736 shelter += BitCount8Bit[shiftRowsDown(pawns, r+i*sign) & 0xFF] * (128 >> i);
738 // Cache shelter value in pawn info
739 ei.pi->setKingShelter(us, s, shelter);
741 ei.mgValue += sign * Value(shelter);
744 // King safety. This is quite complicated, and is almost certainly far
745 // from optimally tuned.
746 Color them = opposite_color(us);
748 if ( p.piece_count(them, QUEEN) >= 1
749 && ei.kingAttackersCount[them] >= 2
750 && p.non_pawn_material(them) >= QueenValueMidgame + RookValueMidgame
751 && ei.kingAdjacentZoneAttacksCount[them])
753 // Is it the attackers turn to move?
754 bool sente = (them == p.side_to_move());
756 // Find the attacked squares around the king which has no defenders
757 // apart from the king itself
758 Bitboard undefended =
759 ei.attacked_by(them) & ~ei.attacked_by(us, PAWN)
760 & ~ei.attacked_by(us, KNIGHT) & ~ei.attacked_by(us, BISHOP)
761 & ~ei.attacked_by(us, ROOK) & ~ei.attacked_by(us, QUEEN)
762 & ei.attacked_by(us, KING);
764 Bitboard occ = p.occupied_squares(), b, b2;
766 // Initialize the 'attackUnits' variable, which is used later on as an
767 // index to the SafetyTable[] array. The initial value is based on the
768 // number and types of the attacking pieces, the number of attacked and
769 // undefended squares around the king, the square of the king, and the
770 // quality of the pawn shelter.
772 Min((ei.kingAttackersCount[them] * ei.kingAttackersWeight[them]) / 2, 25)
773 + (ei.kingAdjacentZoneAttacksCount[them] + count_1s_max_15<HasPopCnt>(undefended)) * 3
774 + InitKingDanger[relative_square(us, s)] - (shelter >> 5);
776 // Analyse safe queen contact checks
777 b = undefended & ei.attacked_by(them, QUEEN) & ~p.pieces_of_color(them);
780 Bitboard attackedByOthers =
781 ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
782 | ei.attacked_by(them, BISHOP) | ei.attacked_by(them, ROOK);
784 b &= attackedByOthers;
787 // The bitboard b now contains the squares available for safe queen
789 int count = count_1s_max_15<HasPopCnt>(b);
790 attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
792 // Is there a mate threat?
793 if (QueenContactMates && !p.is_check())
795 Bitboard escapeSquares =
796 p.piece_attacks<KING>(s) & ~p.pieces_of_color(us) & ~attackedByOthers;
800 Square from, to = pop_1st_bit(&b);
801 if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[s])))
803 // We have a mate, unless the queen is pinned or there
804 // is an X-ray attack through the queen.
805 for (int i = 0; i < p.piece_count(them, QUEEN); i++)
807 from = p.piece_list(them, QUEEN, i);
808 if ( bit_is_set(p.piece_attacks<QUEEN>(from), to)
809 && !bit_is_set(p.pinned_pieces(them), from)
810 && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & p.rooks_and_queens(us))
811 && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & p.bishops_and_queens(us)))
813 ei.mateThreat[them] = make_move(from, to);
821 // Analyse safe distance checks
822 if (QueenCheckBonus > 0 || RookCheckBonus > 0)
824 b = p.piece_attacks<ROOK>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
827 b2 = b & ei.attacked_by(them, QUEEN);
829 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
832 b2 = b & ei.attacked_by(them, ROOK);
834 attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b2);
836 if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
838 b = p.piece_attacks<BISHOP>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
841 b2 = b & ei.attacked_by(them, QUEEN);
843 attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b2);
846 b2 = b & ei.attacked_by(them, BISHOP);
848 attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b2);
850 if (KnightCheckBonus > 0)
852 b = p.piece_attacks<KNIGHT>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
855 b2 = b & ei.attacked_by(them, KNIGHT);
857 attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b2);
860 // Analyse discovered checks (only for non-pawns right now, consider
861 // adding pawns later).
862 if (DiscoveredCheckBonus)
864 b = p.discovered_check_candidates(them) & ~p.pawns();
866 attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente? 2 : 1);
869 // Has a mate threat been found? We don't do anything here if the
870 // side with the mating move is the side to move, because in that
871 // case the mating side will get a huge bonus at the end of the main
872 // evaluation function instead.
873 if (ei.mateThreat[them] != MOVE_NONE)
874 attackUnits += MateThreatBonus;
876 // Ensure that attackUnits is between 0 and 99, in order to avoid array
877 // out of bounds errors:
881 if (attackUnits >= 100)
884 // Finally, extract the king safety score from the SafetyTable[] array.
885 // Add the score to the evaluation, and also to ei.futilityMargin. The
886 // reason for adding the king safety score to the futility margin is
887 // that the king safety scores can sometimes be very big, and that
888 // capturing a single attacking piece can therefore result in a score
889 // change far bigger than the value of the captured piece.
890 Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[us]);
892 ei.mgValue -= sign * v;
894 if (us == p.side_to_move())
895 ei.futilityMargin += v;
900 // evaluate_passed_pawns() evaluates the passed pawns for both sides.
902 void evaluate_passed_pawns(const Position &pos, EvalInfo &ei) {
904 bool hasUnstoppable[2] = {false, false};
905 int movesToGo[2] = {100, 100};
907 for (Color us = WHITE; us <= BLACK; us++)
909 Color them = opposite_color(us);
910 Square ourKingSq = pos.king_square(us);
911 Square theirKingSq = pos.king_square(them);
912 Bitboard b = ei.pi->passed_pawns() & pos.pawns(us), b2, b3, b4;
916 Square s = pop_1st_bit(&b);
918 assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN));
919 assert(pos.pawn_is_passed(us, s));
921 int r = int(relative_rank(us, s) - RANK_2);
922 int tr = Max(0, r * (r - 1));
923 Square blockSq = s + pawn_push(us);
925 // Base bonus based on rank
926 Value mbonus = Value(20 * tr);
927 Value ebonus = Value(10 + r * r * 10);
929 // Adjust bonus based on king proximity
932 ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
933 ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(us)) * 1 * tr);
934 ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
936 // If the pawn is free to advance, increase bonus
937 if (pos.square_is_empty(blockSq))
939 b2 = squares_in_front_of(us, s);
940 b3 = b2 & ei.attacked_by(them);
941 b4 = b2 & ei.attacked_by(us);
943 // If there is an enemy rook or queen attacking the pawn from behind,
944 // add all X-ray attacks by the rook or queen.
945 if ( bit_is_set(ei.attacked_by(them,ROOK) | ei.attacked_by(them,QUEEN),s)
946 && (squares_behind(us, s) & pos.rooks_and_queens(them)))
949 // Squares attacked or occupied by enemy pieces
950 b3 |= (b2 & pos.pieces_of_color(them));
952 // There are no enemy pawns in the pawn's path
953 assert((b2 & pos.pieces_of_color_and_type(them, PAWN)) == EmptyBoardBB);
955 // Are any of the squares in the pawn's path attacked or occupied by the enemy?
956 if (b3 == EmptyBoardBB)
957 // No enemy attacks or pieces, huge bonus!
958 ebonus += Value(tr * (b2 == b4 ? 17 : 15));
960 // OK, there are enemy attacks or pieces (but not pawns). Are those
961 // squares which are attacked by the enemy also attacked by us?
962 // If yes, big bonus (but smaller than when there are no enemy attacks),
963 // if no, somewhat smaller bonus.
964 ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
966 // At last, add a small bonus when there are no *friendly* pieces
967 // in the pawn's path.
968 if ((b2 & pos.pieces_of_color(us)) == EmptyBoardBB)
973 // If the pawn is supported by a friendly pawn, increase bonus
974 b2 = pos.pawns(us) & neighboring_files_bb(s);
976 ebonus += Value(r * 20);
977 else if (pos.pawn_attacks(them, s) & b2)
978 ebonus += Value(r * 12);
980 // If the other side has only a king, check whether the pawn is
982 if (pos.non_pawn_material(them) == Value(0))
987 qsq = relative_square(us, make_square(square_file(s), RANK_8));
988 d = square_distance(s, qsq)
989 - square_distance(theirKingSq, qsq)
990 + (us != pos.side_to_move());
994 int mtg = RANK_8 - relative_rank(us, s);
995 int blockerCount = count_1s_max_15(squares_in_front_of(us,s) & pos.occupied_squares());
1000 hasUnstoppable[us] = true;
1001 movesToGo[us] = Min(movesToGo[us], mtg);
1005 // Rook pawns are a special case: They are sometimes worse, and
1006 // sometimes better than other passed pawns. It is difficult to find
1007 // good rules for determining whether they are good or bad. For now,
1008 // we try the following: Increase the value for rook pawns if the
1009 // other side has no pieces apart from a knight, and decrease the
1010 // value if the other side has a rook or queen.
1011 if (square_file(s) == FILE_A || square_file(s) == FILE_H)
1013 if ( pos.non_pawn_material(them) <= KnightValueMidgame
1014 && pos.piece_count(them, KNIGHT) <= 1)
1015 ebonus += ebonus / 4;
1016 else if (pos.rooks_and_queens(them))
1017 ebonus -= ebonus / 4;
1020 // Add the scores for this pawn to the middle game and endgame eval.
1021 ei.mgValue += apply_weight(Sign[us] * mbonus, WeightPassedPawnsMidgame);
1022 ei.egValue += apply_weight(Sign[us] * ebonus, WeightPassedPawnsEndgame);
1026 // Does either side have an unstoppable passed pawn?
1027 if (hasUnstoppable[WHITE] && !hasUnstoppable[BLACK])
1028 ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]);
1029 else if (hasUnstoppable[BLACK] && !hasUnstoppable[WHITE])
1030 ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]);
1031 else if (hasUnstoppable[BLACK] && hasUnstoppable[WHITE])
1033 // Both sides have unstoppable pawns! Try to find out who queens
1034 // first. We begin by transforming 'movesToGo' to the number of
1035 // plies until the pawn queens for both sides.
1036 movesToGo[WHITE] *= 2;
1037 movesToGo[BLACK] *= 2;
1038 movesToGo[pos.side_to_move()]--;
1040 // If one side queens at least three plies before the other, that
1042 if (movesToGo[WHITE] <= movesToGo[BLACK] - 3)
1043 ei.egValue += UnstoppablePawnValue - Value(0x40 * (movesToGo[WHITE]/2));
1044 else if(movesToGo[BLACK] <= movesToGo[WHITE] - 3)
1045 ei.egValue -= UnstoppablePawnValue - Value(0x40 * (movesToGo[BLACK]/2));
1047 // We could also add some rules about the situation when one side
1048 // queens exactly one ply before the other: Does the first queen
1049 // check the opponent's king, or attack the opponent's queening square?
1050 // This is slightly tricky to get right, because it is possible that
1051 // the opponent's king has moved somewhere before the first pawn queens.
1056 // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
1057 // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
1060 void evaluate_trapped_bishop_a7h7(const Position &pos, Square s, Color us,
1062 assert(square_is_ok(s));
1063 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1065 Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
1066 Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
1068 if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
1069 && pos.see(s, b6) < 0
1070 && pos.see(s, b8) < 0)
1072 ei.mgValue -= Sign[us] * TrappedBishopA7H7Penalty;
1073 ei.egValue -= Sign[us] * TrappedBishopA7H7Penalty;
1078 // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
1079 // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
1080 // black), and assigns a penalty if it is. This pattern can obviously
1081 // only occur in Chess960 games.
1083 void evaluate_trapped_bishop_a1h1(const Position &pos, Square s, Color us,
1085 Piece pawn = piece_of_color_and_type(us, PAWN);
1089 assert(square_is_ok(s));
1090 assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
1092 if (square_file(s) == FILE_A)
1094 b2 = relative_square(us, SQ_B2);
1095 b3 = relative_square(us, SQ_B3);
1096 c3 = relative_square(us, SQ_C3);
1100 b2 = relative_square(us, SQ_G2);
1101 b3 = relative_square(us, SQ_G3);
1102 c3 = relative_square(us, SQ_F3);
1105 if (pos.piece_on(b2) == pawn)
1109 if (!pos.square_is_empty(b3))
1110 penalty = 2*TrappedBishopA1H1Penalty;
1111 else if (pos.piece_on(c3) == pawn)
1112 penalty = TrappedBishopA1H1Penalty;
1114 penalty = TrappedBishopA1H1Penalty / 2;
1116 ei.mgValue -= Sign[us] * penalty;
1117 ei.egValue -= Sign[us] * penalty;
1122 // evaluate_space() computes the space evaluation for a given side. The
1123 // space evaluation is a simple bonus based on the number of safe squares
1124 // available for minor pieces on the central four files on ranks 2--4. Safe
1125 // squares one, two or three squares behind a friendly pawn are counted
1126 // twice. Finally, the space bonus is scaled by a weight taken from the
1127 // material hash table.
1128 template<bool HasPopCnt>
1129 void evaluate_space(const Position &pos, Color us, EvalInfo &ei) {
1131 Color them = opposite_color(us);
1133 // Find the safe squares for our pieces inside the area defined by
1134 // SpaceMask[us]. A square is unsafe it is attacked by an enemy
1135 // pawn, or if it is undefended and attacked by an enemy piece.
1137 Bitboard safeSquares = SpaceMask[us]
1139 & ~ei.attacked_by(them, PAWN)
1140 & ~(~ei.attacked_by(us) & ei.attacked_by(them));
1142 // Find all squares which are at most three squares behind some friendly
1144 Bitboard behindFriendlyPawns = pos.pawns(us);
1147 behindFriendlyPawns |= (behindFriendlyPawns >> 8);
1148 behindFriendlyPawns |= (behindFriendlyPawns >> 16);
1152 behindFriendlyPawns |= (behindFriendlyPawns << 8);
1153 behindFriendlyPawns |= (behindFriendlyPawns << 16);
1156 int space = count_1s_max_15<HasPopCnt>(safeSquares)
1157 + count_1s_max_15<HasPopCnt>(behindFriendlyPawns & safeSquares);
1159 ei.mgValue += Sign[us] * apply_weight(Value(space * ei.mi->space_weight()), WeightSpace);
1163 // apply_weight() applies an evaluation weight to a value
1165 inline Value apply_weight(Value v, int w) {
1166 return (v*w) / 0x100;
1170 // scale_by_game_phase() interpolates between a middle game and an endgame
1171 // score, based on game phase. It also scales the return value by a
1172 // ScaleFactor array.
1174 Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
1176 assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
1177 assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
1178 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1180 ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
1182 Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
1183 return Value(int(result) & ~(GrainSize - 1));
1187 // compute_weight() computes the value of an evaluation weight, by combining
1188 // an UCI-configurable weight with an internal weight.
1190 int compute_weight(int uciWeight, int internalWeight) {
1192 uciWeight = (uciWeight * 0x100) / 100;
1193 return (uciWeight * internalWeight) / 0x100;
1197 // helper used in read_weights()
1198 int weight_option(const std::string& opt, int weight) {
1200 return compute_weight(get_option_value_int(opt), weight);
1204 // init_safety() initizes the king safety evaluation, based on UCI
1205 // parameters. It is called from read_weights().
1207 void init_safety() {
1209 QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
1210 QueenCheckBonus = get_option_value_int("Queen Check Bonus");
1211 RookCheckBonus = get_option_value_int("Rook Check Bonus");
1212 BishopCheckBonus = get_option_value_int("Bishop Check Bonus");
1213 KnightCheckBonus = get_option_value_int("Knight Check Bonus");
1214 DiscoveredCheckBonus = get_option_value_int("Discovered Check Bonus");
1215 MateThreatBonus = get_option_value_int("Mate Threat Bonus");
1217 int maxSlope = get_option_value_int("King Safety Max Slope");
1218 int peak = get_option_value_int("King Safety Max Value") * 256 / 100;
1219 double a = get_option_value_int("King Safety Coefficient") / 100.0;
1220 double b = get_option_value_int("King Safety X Intercept");
1221 bool quad = (get_option_value_string("King Safety Curve") == "Quadratic");
1222 bool linear = (get_option_value_string("King Safety Curve") == "Linear");
1224 for (int i = 0; i < 100; i++)
1227 SafetyTable[i] = Value(0);
1229 SafetyTable[i] = Value((int)(a * (i - b) * (i - b)));
1231 SafetyTable[i] = Value((int)(100 * a * (i - b)));
1234 for (int i = 0; i < 100; i++)
1236 if (SafetyTable[i+1] - SafetyTable[i] > maxSlope)
1237 for (int j = i + 1; j < 100; j++)
1238 SafetyTable[j] = SafetyTable[j-1] + Value(maxSlope);
1240 if (SafetyTable[i] > Value(peak))
1241 SafetyTable[i] = Value(peak);