X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=e582692e3251c38bd7df3cbf3404aa0a8c5841c3;hp=3634f95746796afef7ab904856629b59d2c970fa;hb=9369f4963d9376820cb5ca4bad66b86e67b0a010;hpb=79fa72f392343fb93c16c133dedc3dbdf795e746 diff --git a/src/pawns.cpp b/src/pawns.cpp index 3634f957..e582692e 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -24,6 +24,7 @@ #include "bitcount.h" #include "pawns.h" #include "position.h" +#include "thread.h" namespace { @@ -49,8 +50,8 @@ namespace { { S(20, 28), S(29, 31), S(33, 31), S(33, 31), S(33, 31), S(33, 31), S(29, 31), S(20, 28) } }; - // Connected pawn bonus by opposed, phalanx flags and rank - Score Connected[2][2][RANK_NB]; + // Connected pawn bonus by opposed, phalanx, twice supported and rank + Score Connected[2][2][2][RANK_NB]; // Levers bonus by rank const Score Lever[RANK_NB] = { @@ -60,20 +61,43 @@ namespace { // Unsupported pawn penalty const Score UnsupportedPawnPenalty = S(20, 10); - // Weakness of our pawn shelter in front of the king indexed by [rank] - const Value ShelterWeakness[RANK_NB] = - { V(100), V(0), V(27), V(73), V(92), V(101), V(101) }; - - // Danger of enemy pawns moving toward our king indexed by - // [no friendly pawn | pawn unblocked | pawn blocked][rank of enemy pawn] - const Value StormDanger[][RANK_NB] = { - { V( 0), V(64), V(128), V(51), V(26) }, - { V(26), V(32), V( 96), V(38), V(20) }, - { V( 0), V( 0), V(160), V(25), V(13) } }; + // Center bind bonus: Two pawns controlling the same central square + const Bitboard CenterBindMask[COLOR_NB] = { + (FileDBB | FileEBB) & (Rank5BB | Rank6BB | Rank7BB), + (FileDBB | FileEBB) & (Rank4BB | Rank3BB | Rank2BB) + }; + + const Score CenterBind = S(16, 0); + + // Weakness of our pawn shelter in front of the king by [distance from edge][rank] + const Value ShelterWeakness[][RANK_NB] = { + { V( 99), V(20), V(26), V(54), V(85), V( 92), V(108) }, + { V(117), V( 1), V(27), V(71), V(94), V(104), V(118) }, + { V(104), V( 4), V(51), V(76), V(82), V(102), V( 97) }, + { V( 80), V(12), V(43), V(65), V(88), V( 91), V(115) } }; + + // Danger of enemy pawns moving toward our king by [type][distance from edge][rank] + const Value StormDanger[][4][RANK_NB] = { + { { V( 0), V( 65), V( 126), V(36), V(30) }, + { V( 0), V( 55), V( 135), V(36), V(23) }, + { V( 0), V( 47), V( 116), V(45), V(26) }, + { V( 0), V( 62), V( 127), V(57), V(34) } }, + { { V(21), V( 45), V( 93), V(50), V(19) }, + { V(23), V( 24), V( 105), V(41), V(13) }, + { V(23), V( 36), V( 101), V(38), V(20) }, + { V(30), V( 19), V( 110), V(41), V(27) } }, + { { V( 0), V( 0), V( 81), V(14), V( 4) }, + { V( 0), V( 0), V( 169), V(30), V( 3) }, + { V( 0), V( 0), V( 168), V(24), V( 5) }, + { V( 0), V( 0), V( 162), V(26), V(10) } }, + { { V( 0), V(-283), V(-298), V(57), V(29) }, + { V( 0), V( 63), V( 137), V(42), V(18) }, + { V( 0), V( 67), V( 145), V(49), V(33) }, + { V( 0), V( 62), V( 126), V(53), V(21) } } }; // Max bonus for king safety. Corresponds to start position with all the pawns // in front of the king and no enemy pawn on the horizon. - const Value MaxSafetyBonus = V(263); + const Value MaxSafetyBonus = V(258); #undef S #undef V @@ -86,10 +110,10 @@ namespace { const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); - Bitboard b, p, doubled, connected; + Bitboard b, p, doubled, connected, supported; Square s; - bool passed, isolated, opposed, phalanx, backward, unsupported, lever; - Score value = SCORE_ZERO; + bool passed, isolated, opposed, phalanx, backward, lever; + Score score = SCORE_ZERO; const Square* pl = pos.list(Us); const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)]; @@ -114,13 +138,12 @@ namespace { e->semiopenFiles[Us] &= ~(1 << f); // Previous rank - p = rank_bb(s - pawn_push(Us)); + p = rank_bb(s - Up); - // Flag the pawn as passed, isolated, doubled, - // unsupported or connected (but not the backward one). + // Flag the pawn connected = ourPawns & adjacent_files_bb(f) & (rank_bb(s) | p); phalanx = connected & rank_bb(s); - unsupported = !(ourPawns & adjacent_files_bb(f) & p); + supported = connected & p; isolated = !(ourPawns & adjacent_files_bb(f)); doubled = ourPawns & forward_bb(Us, s); opposed = theirPawns & forward_bb(Us, s); @@ -128,16 +151,15 @@ namespace { lever = theirPawns & pawnAttacksBB[s]; // Test for backward pawn. - // If the pawn is passed, isolated, or connected it cannot be + // If the pawn is passed, isolated, connected or a lever it cannot be // backward. If there are friendly pawns behind on adjacent files - // or if it can capture an enemy pawn it cannot be backward either. - if ( (passed | isolated | connected) - || (ourPawns & pawn_attack_span(Them, s)) - || (pos.attacks_from(s, Us) & theirPawns)) + // it cannot be backward either. + if ( (passed | isolated | lever | connected) + || (ourPawns & pawn_attack_span(Them, s))) backward = false; else { - // We now know that there are no friendly pawns beside or behind this + // We now know there are no friendly pawns beside or behind this // pawn on adjacent files. We now check whether the pawn is // backward by looking in the forward direction on the adjacent // files, and picking the closest pawn there. @@ -159,37 +181,41 @@ namespace { // Score this pawn if (isolated) - value -= Isolated[opposed][f]; + score -= Isolated[opposed][f]; - if (unsupported && !isolated) - value -= UnsupportedPawnPenalty; + if (!supported && !isolated) + score -= UnsupportedPawnPenalty; if (doubled) - value -= Doubled[f] / rank_distance(s, lsb(doubled)); + score -= Doubled[f] / distance(s, frontmost_sq(Us, doubled)); if (backward) - value -= Backward[opposed][f]; + score -= Backward[opposed][f]; if (connected) - value += Connected[opposed][phalanx][relative_rank(Us, s)]; + score += Connected[opposed][phalanx][more_than_one(supported)][relative_rank(Us, s)]; if (lever) - value += Lever[relative_rank(Us, s)]; + score += Lever[relative_rank(Us, s)]; } b = e->semiopenFiles[Us] ^ 0xFF; e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; - return value; + // Center binds: Two pawns controlling the same central square + b = shift_bb(ourPawns) & shift_bb(ourPawns) & CenterBindMask[Us]; + score += popcount(b) * CenterBind; + + return score; } } // namespace namespace Pawns { -/// init() initializes some tables used by evaluation. Instead of hard-coded -/// tables, when makes sense, we prefer to calculate them with a formula to -/// reduce independent parameters and to allow easier tuning and better insight. +/// Pawns::init() initializes some tables needed by evaluation. Instead of using +/// hard-coded tables, when makes sense, we prefer to calculate them with a formula +/// to reduce independent parameters and to allow easier tuning and better insight. void init() { @@ -197,28 +223,31 @@ void init() for (int opposed = 0; opposed <= 1; ++opposed) for (int phalanx = 0; phalanx <= 1; ++phalanx) - for (Rank r = RANK_2; r < RANK_8; ++r) - { - int bonus = Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0); - Connected[opposed][phalanx][r] = make_score(bonus / 2, bonus >> opposed); - } + for (int apex = 0; apex <= 1; ++apex) + for (Rank r = RANK_2; r < RANK_8; ++r) + { + int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; + v += (apex ? v / 2 : 0); + Connected[opposed][phalanx][apex][r] = make_score(3 * v / 2, v); + } } -/// probe() takes a position as input, computes a Entry object, and returns a -/// pointer to it. The result is also stored in a hash table, so we don't have -/// to recompute everything when the same pawn structure occurs again. +/// Pawns::probe() looks up the current position's pawns configuration in +/// the pawns hash table. It returns a pointer to the Entry if the position +/// is found. Otherwise a new Entry is computed and stored there, so we don't +/// have to recompute all when the same pawns configuration occurs again. -Entry* probe(const Position& pos, Table& entries) { +Entry* probe(const Position& pos) { Key key = pos.pawn_key(); - Entry* e = entries[key]; + Entry* e = pos.this_thread()->pawnsTable[key]; if (e->key == key) return e; e->key = key; - e->value = evaluate(pos, e) - evaluate(pos, e); + e->score = evaluate(pos, e) - evaluate(pos, e); return e; } @@ -230,15 +259,16 @@ template Value Entry::shelter_storm(const Position& pos, Square ksq) { const Color Them = (Us == WHITE ? BLACK : WHITE); - const Bitboard Edges = (FileABB | FileHBB) & (Rank2BB | Rank3BB); + + enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing }; Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); Bitboard ourPawns = b & pos.pieces(Us); Bitboard theirPawns = b & pos.pieces(Them); Value safety = MaxSafetyBonus; - File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); + File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); - for (File f = kf - File(1); f <= kf + File(1); ++f) + for (File f = center - File(1); f <= center + File(1); ++f) { b = ourPawns & file_bb(f); Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; @@ -246,14 +276,12 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { b = theirPawns & file_bb(f); Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - if ( (Edges & make_square(f, rkThem)) - && file_of(ksq) == f - && relative_rank(Us, ksq) == rkThem - 1) - safety += 200; - else - safety -= ShelterWeakness[rkUs] - + StormDanger[rkUs == RANK_1 ? 0 : - rkThem != rkUs + 1 ? 1 : 2][rkThem]; + safety -= ShelterWeakness[std::min(f, FILE_H - f)][rkUs] + + StormDanger + [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing : + rkUs == RANK_1 ? NoFriendlyPawn : + rkThem == rkUs + 1 ? BlockedByPawn : Unblocked] + [std::min(f, FILE_H - f)][rkThem]; } return safety; @@ -268,14 +296,14 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) { kingSquares[Us] = ksq; castlingRights[Us] = pos.can_castle(Us); - minKPdistance[Us] = 0; + minKingPawnDistance[Us] = 0; Bitboard pawns = pos.pieces(Us, PAWN); if (pawns) - while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {} + while (!(DistanceRingBB[ksq][minKingPawnDistance[Us]++] & pawns)) {} if (relative_rank(Us, ksq) > RANK_4) - return make_score(0, -16 * minKPdistance[Us]); + return make_score(0, -16 * minKingPawnDistance[Us]); Value bonus = shelter_storm(pos, ksq); @@ -286,7 +314,7 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) { if (pos.can_castle(MakeCastling::right)) bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); - return make_score(bonus, -16 * minKPdistance[Us]); + return make_score(bonus, -16 * minKingPawnDistance[Us]); } // Explicit template instantiation