X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=3f8094b6d0c321c5105b7008b7eb9ea69df689f6;hp=97274946b00c243e50852fd854b8ca8c52f25953;hb=35018fa3076a01a62bd4433771c5832d0ddc52e8;hpb=5b2ac7590ccfe529698347981e45fdfa8a0a0780 diff --git a/src/endgame.cpp b/src/endgame.cpp index 97274946..3f8094b6 100644 --- a/src/endgame.cpp +++ b/src/endgame.cpp @@ -17,27 +17,21 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include #include "bitcount.h" #include "endgame.h" #include "pawns.h" +using std::string; -//// -//// Local definitions -//// +extern uint32_t probe_kpk_bitbase(Square wksq, Square wpsq, Square bksq, Color stm); namespace { // Table used to drive the defending king towards the edge of the board // in KX vs K and KQ vs KR endgames. - const uint8_t MateTable[64] = { + const int MateTable[64] = { 100, 90, 80, 70, 70, 80, 90, 100, 90, 70, 60, 50, 50, 60, 70, 90, 80, 60, 40, 30, 30, 40, 60, 80, @@ -50,7 +44,7 @@ namespace { // Table used to drive the defending king towards a corner square of the // right color in KBN vs K endgames. - const uint8_t KBNKMateTable[64] = { + const int KBNKMateTable[64] = { 200, 190, 180, 170, 160, 150, 140, 130, 190, 180, 170, 160, 150, 140, 130, 140, 180, 170, 155, 140, 140, 125, 140, 150, @@ -69,43 +63,80 @@ namespace { // and knight in KR vs KN endgames. const int KRKNKingKnightDistancePenalty[8] = { 0, 0, 4, 10, 20, 32, 48, 70 }; - // Bitbase for KP vs K - uint8_t KPKBitbase[24576]; + // Build corresponding key code for the opposite color: "KBPKN" -> "KNKBP" + const string swap_colors(const string& keyCode) { - // Various inline functions for accessing the above arrays - inline Value mate_table(Square s) { - return Value(MateTable[s]); + size_t idx = keyCode.find('K', 1); + return keyCode.substr(idx) + keyCode.substr(0, idx); } - inline Value kbnk_mate_table(Square s) { - return Value(KBNKMateTable[s]); - } + // Get the material key of a position out of the given endgame key code + // like "KBPKN". The trick here is to first build up a FEN string and then + // let a Position object to do the work for us. Note that the FEN string + // could correspond to an illegal position. + Key mat_key(const string& keyCode) { - inline Value distance_bonus(int d) { - return Value(DistanceBonus[d]); - } + assert(keyCode.length() > 0 && keyCode.length() < 8); + assert(keyCode[0] == 'K'); + + string fen; + size_t i = 0; + + // First add white and then black pieces + do fen += keyCode[i]; while (keyCode[++i] != 'K'); + do fen += char(tolower(keyCode[i])); while (++i < keyCode.length()); + + // Add file padding and remaining empty ranks + fen += string(1, '0' + int(8 - keyCode.length())) + "/8/8/8/8/8/8/8 w - - 0 10"; - inline Value krkn_king_knight_distance_penalty(int d) { - return Value(KRKNKingKnightDistancePenalty[d]); + // Build a Position out of the fen string and get its material key + return Position(fen, false, 0).get_material_key(); } - // Function for probing the KP vs K bitbase - int probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm); +} // namespace + +/// Endgames member definitions + +template<> const Endgames::M1& Endgames::map() const { return m1; } +template<> const Endgames::M2& Endgames::map() const { return m2; } + +Endgames::Endgames() { + + add("KPK"); + add("KNNK"); + add("KBNK"); + add("KRKP"); + add("KRKB"); + add("KRKN"); + add("KQKR"); + add("KBBKN"); + + add("KNPK"); + add("KRPKR"); + add("KBPKB"); + add("KBPKN"); + add("KBPPKB"); + add("KRPPKRP"); } +Endgames::~Endgames() { -//// -//// Functions -//// + for (M1::const_iterator it = m1.begin(); it != m1.end(); ++it) + delete it->second; -/// init_bitbases() is called during program initialization, and simply loads -/// bitbases from disk into memory. At the moment, there is only the bitbase -/// for KP vs K, but we may decide to add other bitbases later. -extern void generate_kpk_bitbase(uint8_t bitbase[]); + for (M2::const_iterator it = m2.begin(); it != m2.end(); ++it) + delete it->second; +} -void init_bitbases() { - generate_kpk_bitbase(KPKBitbase); +template +void Endgames::add(const string& keyCode) { + + typedef typename eg_family::type T; + typedef typename Map::type M; + + const_cast(map()).insert(std::make_pair(mat_key(keyCode), new Endgame(WHITE))); + const_cast(map()).insert(std::make_pair(mat_key(swap_colors(keyCode)), new Endgame(BLACK))); } @@ -114,7 +145,7 @@ void init_bitbases() { /// attacking side a bonus for driving the defending king towards the edge /// of the board, and for keeping the distance between the two kings small. template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO); @@ -124,8 +155,8 @@ Value EvaluationFunction::apply(const Position& pos) const { Value result = pos.non_pawn_material(strongerSide) + pos.piece_count(strongerSide, PAWN) * PawnValueEndgame - + mate_table(loserKSq) - + distance_bonus(square_distance(winnerKSq, loserKSq)); + + MateTable[loserKSq] + + DistanceBonus[square_distance(winnerKSq, loserKSq)]; if ( pos.piece_count(strongerSide, QUEEN) || pos.piece_count(strongerSide, ROOK) @@ -140,7 +171,7 @@ Value EvaluationFunction::apply(const Position& pos) const { /// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the /// defending king towards a corner square of the right color. template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO); @@ -151,7 +182,7 @@ Value EvaluationFunction::apply(const Position& pos) const { Square winnerKSq = pos.king_square(strongerSide); Square loserKSq = pos.king_square(weakerSide); - Square bishopSquare = pos.piece_list(strongerSide, BISHOP, 0); + Square bishopSquare = pos.piece_list(strongerSide, BISHOP)[0]; // kbnk_mate_table() tries to drive toward corners A1 or H8, // if we have a bishop that cannot reach the above squares we @@ -163,8 +194,8 @@ Value EvaluationFunction::apply(const Position& pos) const { } Value result = VALUE_KNOWN_WIN - + distance_bonus(square_distance(winnerKSq, loserKSq)) - + kbnk_mate_table(loserKSq); + + DistanceBonus[square_distance(winnerKSq, loserKSq)] + + KBNKMateTable[loserKSq]; return strongerSide == pos.side_to_move() ? result : -result; } @@ -172,7 +203,7 @@ Value EvaluationFunction::apply(const Position& pos) const { /// KP vs K. This endgame is evaluated with the help of a bitbase. template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO); assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); @@ -186,14 +217,14 @@ Value EvaluationFunction::apply(const Position& pos) const { { wksq = pos.king_square(WHITE); bksq = pos.king_square(BLACK); - wpsq = pos.piece_list(WHITE, PAWN, 0); + wpsq = pos.piece_list(WHITE, PAWN)[0]; stm = pos.side_to_move(); } else { wksq = flip_square(pos.king_square(BLACK)); bksq = flip_square(pos.king_square(WHITE)); - wpsq = flip_square(pos.piece_list(BLACK, PAWN, 0)); + wpsq = flip_square(pos.piece_list(BLACK, PAWN)[0]); stm = opposite_color(pos.side_to_move()); } @@ -204,7 +235,7 @@ Value EvaluationFunction::apply(const Position& pos) const { wpsq = flop_square(wpsq); } - if (!probe_kpk(wksq, wpsq, bksq, stm)) + if (!probe_kpk_bitbase(wksq, wpsq, bksq, stm)) return VALUE_DRAW; Value result = VALUE_KNOWN_WIN @@ -220,7 +251,7 @@ Value EvaluationFunction::apply(const Position& pos) const { /// far advanced with support of the king, while the attacking king is far /// away. template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -231,9 +262,9 @@ Value EvaluationFunction::apply(const Position& pos) const { int tempo = (pos.side_to_move() == strongerSide); wksq = pos.king_square(strongerSide); - wrsq = pos.piece_list(strongerSide, ROOK, 0); + wrsq = pos.piece_list(strongerSide, ROOK)[0]; bksq = pos.king_square(weakerSide); - bpsq = pos.piece_list(weakerSide, PAWN, 0); + bpsq = pos.piece_list(weakerSide, PAWN)[0]; if (strongerSide == BLACK) { @@ -277,7 +308,7 @@ Value EvaluationFunction::apply(const Position& pos) const { /// KR vs KB. This is very simple, and always returns drawish scores. The /// score is slightly bigger when the defending king is close to the edge. template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -285,7 +316,7 @@ Value EvaluationFunction::apply(const Position& pos) const { assert(pos.piece_count(weakerSide, PAWN) == 0); assert(pos.piece_count(weakerSide, BISHOP) == 1); - Value result = mate_table(pos.king_square(weakerSide)); + Value result = Value(MateTable[pos.king_square(weakerSide)]); return strongerSide == pos.side_to_move() ? result : -result; } @@ -293,7 +324,7 @@ Value EvaluationFunction::apply(const Position& pos) const { /// KR vs KN. The attacking side has slightly better winning chances than /// in KR vs KB, particularly if the king and the knight are far apart. template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -302,12 +333,12 @@ Value EvaluationFunction::apply(const Position& pos) const { assert(pos.piece_count(weakerSide, KNIGHT) == 1); Square defendingKSq = pos.king_square(weakerSide); - Square nSq = pos.piece_list(weakerSide, KNIGHT, 0); + Square nSq = pos.piece_list(weakerSide, KNIGHT)[0]; int d = square_distance(defendingKSq, nSq); Value result = Value(10) - + mate_table(defendingKSq) - + krkn_king_knight_distance_penalty(d); + + MateTable[defendingKSq] + + KRKNKingKnightDistancePenalty[d]; return strongerSide == pos.side_to_move() ? result : -result; } @@ -319,7 +350,7 @@ Value EvaluationFunction::apply(const Position& pos) const { /// for the defending side in the search, this is usually sufficient to be /// able to win KQ vs KR. template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -331,14 +362,14 @@ Value EvaluationFunction::apply(const Position& pos) const { Value result = QueenValueEndgame - RookValueEndgame - + mate_table(loserKSq) - + distance_bonus(square_distance(winnerKSq, loserKSq)); + + MateTable[loserKSq] + + DistanceBonus[square_distance(winnerKSq, loserKSq)]; return strongerSide == pos.side_to_move() ? result : -result; } template<> -Value EvaluationFunction::apply(const Position& pos) const { +Value Endgame::apply(const Position& pos) const { assert(pos.piece_count(strongerSide, BISHOP) == 2); assert(pos.non_pawn_material(strongerSide) == 2*BishopValueMidgame); @@ -349,10 +380,10 @@ Value EvaluationFunction::apply(const Position& pos) const { Value result = BishopValueEndgame; Square wksq = pos.king_square(strongerSide); Square bksq = pos.king_square(weakerSide); - Square nsq = pos.piece_list(weakerSide, KNIGHT, 0); + Square nsq = pos.piece_list(weakerSide, KNIGHT)[0]; // Bonus for attacking king close to defending king - result += distance_bonus(square_distance(wksq, bksq)); + result += Value(DistanceBonus[square_distance(wksq, bksq)]); // Bonus for driving the defending king and knight apart result += Value(square_distance(bksq, nsq) * 32); @@ -367,12 +398,12 @@ Value EvaluationFunction::apply(const Position& pos) const { /// K and two minors vs K and one or two minors or K and two knights against /// king alone are always draw. template<> -Value EvaluationFunction::apply(const Position&) const { +Value Endgame::apply(const Position&) const { return VALUE_DRAW; } template<> -Value EvaluationFunction::apply(const Position&) const { +Value Endgame::apply(const Position&) const { return VALUE_DRAW; } @@ -382,7 +413,7 @@ Value EvaluationFunction::apply(const Position&) const { /// returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling /// will be used. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -392,13 +423,13 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { // be detected even when the weaker side has some pawns. Bitboard pawns = pos.pieces(PAWN, strongerSide); - File pawnFile = square_file(pos.piece_list(strongerSide, PAWN, 0)); + File pawnFile = square_file(pos.piece_list(strongerSide, PAWN)[0]); // All pawns are on a single rook file ? if ( (pawnFile == FILE_A || pawnFile == FILE_H) && (pawns & ~file_bb(pawnFile)) == EmptyBoardBB) { - Square bishopSq = pos.piece_list(strongerSide, BISHOP, 0); + Square bishopSq = pos.piece_list(strongerSide, BISHOP)[0]; Square queeningSq = relative_square(strongerSide, make_square(pawnFile, RANK_8)); Square kingSq = pos.king_square(weakerSide); @@ -436,7 +467,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// It tests for fortress draws with a rook on the third rank defended by /// a pawn. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, QUEEN) == 1); @@ -451,7 +482,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { && (pos.pieces(PAWN, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_2))) && (pos.attacks_from(kingSq) & pos.pieces(PAWN, weakerSide))) { - Square rsq = pos.piece_list(weakerSide, ROOK, 0); + Square rsq = pos.piece_list(weakerSide, ROOK)[0]; if (pos.attacks_from(rsq, strongerSide) & pos.pieces(PAWN, weakerSide)) return SCALE_FACTOR_ZERO; } @@ -467,7 +498,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// It would also be nice to rewrite the actual code for this function, /// which is mostly copied from Glaurung 1.x, and not very pretty. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 1); @@ -475,10 +506,10 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.piece_count(weakerSide, PAWN) == 0); Square wksq = pos.king_square(strongerSide); - Square wrsq = pos.piece_list(strongerSide, ROOK, 0); - Square wpsq = pos.piece_list(strongerSide, PAWN, 0); + Square wrsq = pos.piece_list(strongerSide, ROOK)[0]; + Square wpsq = pos.piece_list(strongerSide, PAWN)[0]; Square bksq = pos.king_square(weakerSide); - Square brsq = pos.piece_list(weakerSide, ROOK, 0); + Square brsq = pos.piece_list(weakerSide, ROOK)[0]; // Orient the board in such a way that the stronger side is white, and the // pawn is on the left half of the board. @@ -585,15 +616,15 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// single pattern: If the stronger side has no pawns and the defending king /// is actively placed, the position is drawish. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 2); assert(pos.non_pawn_material(weakerSide) == RookValueMidgame); assert(pos.piece_count(weakerSide, PAWN) == 1); - Square wpsq1 = pos.piece_list(strongerSide, PAWN, 0); - Square wpsq2 = pos.piece_list(strongerSide, PAWN, 1); + Square wpsq1 = pos.piece_list(strongerSide, PAWN)[0]; + Square wpsq2 = pos.piece_list(strongerSide, PAWN)[1]; Square bksq = pos.king_square(weakerSide); // Does the stronger side have a passed pawn? @@ -624,7 +655,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// against king. There is just a single rule here: If all pawns are on /// the same rook file and are blocked by the defending king, it's a draw. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO); assert(pos.piece_count(strongerSide, PAWN) >= 2); @@ -662,7 +693,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// it's a draw. If the two bishops have opposite color, it's almost always /// a draw. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -671,9 +702,9 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.piece_count(weakerSide, BISHOP) == 1); assert(pos.piece_count(weakerSide, PAWN) == 0); - Square pawnSq = pos.piece_list(strongerSide, PAWN, 0); - Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP, 0); - Square weakerBishopSq = pos.piece_list(weakerSide, BISHOP, 0); + Square pawnSq = pos.piece_list(strongerSide, PAWN)[0]; + Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP)[0]; + Square weakerBishopSq = pos.piece_list(weakerSide, BISHOP)[0]; Square weakerKingSq = pos.king_square(weakerSide); // Case 1: Defending king blocks the pawn, and cannot be driven away @@ -717,7 +748,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// KBPPKBScalingFunction scales KBPP vs KB endgames. It detects a few basic /// draws with opposite-colored bishops. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -726,15 +757,15 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.piece_count(weakerSide, BISHOP) == 1); assert(pos.piece_count(weakerSide, PAWN) == 0); - Square wbsq = pos.piece_list(strongerSide, BISHOP, 0); - Square bbsq = pos.piece_list(weakerSide, BISHOP, 0); + Square wbsq = pos.piece_list(strongerSide, BISHOP)[0]; + Square bbsq = pos.piece_list(weakerSide, BISHOP)[0]; if (!opposite_color_squares(wbsq, bbsq)) return SCALE_FACTOR_NONE; Square ksq = pos.king_square(weakerSide); - Square psq1 = pos.piece_list(strongerSide, PAWN, 0); - Square psq2 = pos.piece_list(strongerSide, PAWN, 1); + Square psq1 = pos.piece_list(strongerSide, PAWN)[0]; + Square psq2 = pos.piece_list(strongerSide, PAWN)[1]; Rank r1 = square_rank(psq1); Rank r2 = square_rank(psq2); Square blockSq1, blockSq2; @@ -793,7 +824,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// square of the king is not of the same color as the stronger side's bishop, /// it's a draw. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -802,8 +833,8 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.piece_count(weakerSide, KNIGHT) == 1); assert(pos.piece_count(weakerSide, PAWN) == 0); - Square pawnSq = pos.piece_list(strongerSide, PAWN, 0); - Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP, 0); + Square pawnSq = pos.piece_list(strongerSide, PAWN)[0]; + Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP)[0]; Square weakerKingSq = pos.king_square(weakerSide); if ( square_file(weakerKingSq) == square_file(pawnSq) @@ -820,7 +851,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// If the pawn is a rook pawn on the 7th rank and the defending king prevents /// the pawn from advancing, the position is drawn. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame); assert(pos.piece_count(strongerSide, KNIGHT) == 1); @@ -828,7 +859,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); assert(pos.piece_count(weakerSide, PAWN) == 0); - Square pawnSq = pos.piece_list(strongerSide, PAWN, 0); + Square pawnSq = pos.piece_list(strongerSide, PAWN)[0]; Square weakerKingSq = pos.king_square(weakerSide); if ( pawnSq == relative_square(strongerSide, SQ_A7) @@ -850,7 +881,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { /// advanced and not on a rook file; in this case it is often possible to win /// (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1). template<> -ScaleFactor ScalingFunction::apply(const Position& pos) const { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO); assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); @@ -864,14 +895,14 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { { wksq = pos.king_square(WHITE); bksq = pos.king_square(BLACK); - wpsq = pos.piece_list(WHITE, PAWN, 0); + wpsq = pos.piece_list(WHITE, PAWN)[0]; stm = pos.side_to_move(); } else { wksq = flip_square(pos.king_square(BLACK)); bksq = flip_square(pos.king_square(WHITE)); - wpsq = flip_square(pos.piece_list(BLACK, PAWN, 0)); + wpsq = flip_square(pos.piece_list(BLACK, PAWN)[0]); stm = opposite_color(pos.side_to_move()); } @@ -890,21 +921,5 @@ ScaleFactor ScalingFunction::apply(const Position& pos) const { // Probe the KPK bitbase with the weakest side's pawn removed. If it's a // draw, it's probably at least a draw even with the pawn. - return probe_kpk(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_ZERO; -} - - -namespace { - - // Probe the KP vs K bitbase - - int probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm) { - - int wp = square_file(wpsq) + 4 * (square_rank(wpsq) - 1); - int index = int(stm) + 2 * bksq + 128 * wksq + 8192 * wp; - - assert(index >= 0 && index < 24576 * 8); - - return KPKBitbase[index / 8] & (1 << (index & 7)); - } + return probe_kpk_bitbase(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_ZERO; }