X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=16b00ec2fa012cbf36e75001e3811e661bc91f1a;hp=4d878e2063419a590e3a18a3633c1b75444820fa;hb=94dd204c3b10ebe0e6c8df5d7c98de5ba4906cad;hpb=ab580106fd995c23aaa7c297e9cbd210cfd33f11 diff --git a/src/pawns.cpp b/src/pawns.cpp index 4d878e20..16b00ec2 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -49,22 +49,14 @@ 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 file and rank (initialized by formula) - Score Connected[FILE_NB][RANK_NB]; - - // Candidate passed pawn bonus by rank - const Score CandidatePassed[RANK_NB] = { - S( 0, 0), S( 6, 13), S(6,13), S(14,29), - S(34,68), S(83,166), S(0, 0), S( 0, 0) }; + // Connected pawn bonus by opposed, phalanx flags and rank + Score Connected[2][2][RANK_NB]; // Levers bonus by rank const Score Lever[RANK_NB] = { S( 0, 0), S( 0, 0), S(0, 0), S(0, 0), S(20,20), S(40,40), S(0, 0), S(0, 0) }; - // Bonus for file distance of the two outermost pawns - const Score PawnsFileSpan = S(0, 15); - // Unsupported pawn penalty const Score UnsupportedPawnPenalty = S(20, 10); @@ -94,18 +86,17 @@ namespace { const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); - Bitboard b, p, doubled; + Bitboard b, p, doubled, connected; Square s; - File f; - bool passed, isolated, opposed, connected, backward, candidate, unsupported, lever; + bool passed, isolated, opposed, phalanx, backward, unsupported, lever; Score value = SCORE_ZERO; const Square* pl = pos.list(Us); const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)]; - Bitboard ourPawns = pos.pieces(Us, PAWN); + Bitboard ourPawns = pos.pieces(Us , PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); - e->passedPawns[Us] = e->candidatePawns[Us] = 0; + e->passedPawns[Us] = 0; e->kingSquares[Us] = SQ_NONE; e->semiopenFiles[Us] = 0xFF; e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns); @@ -117,7 +108,7 @@ namespace { { assert(pos.piece_on(s) == make_piece(Us, PAWN)); - f = file_of(s); + File f = file_of(s); // This file cannot be semi-open e->semiopenFiles[Us] &= ~(1 << f); @@ -125,12 +116,10 @@ namespace { // Previous rank p = rank_bb(s - pawn_push(Us)); - // Our rank plus previous one - b = rank_bb(s) | p; - // Flag the pawn as passed, isolated, doubled, // unsupported or connected (but not the backward one). - connected = ourPawns & adjacent_files_bb(f) & b; + connected = ourPawns & adjacent_files_bb(f) & (rank_bb(s) | p); + phalanx = connected & rank_bb(s); unsupported = !(ourPawns & adjacent_files_bb(f) & p); isolated = !(ourPawns & adjacent_files_bb(f)); doubled = ourPawns & forward_bb(Us, s); @@ -162,14 +151,6 @@ namespace { assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns)); - // A not-passed pawn is a candidate to become passed, if it is free to - // advance and if the number of friendly pawns beside or behind this - // pawn on adjacent files is higher than or equal to the number of - // enemy pawns in the forward direction on the adjacent files. - candidate = !(opposed | passed | backward | isolated) - && (b = pawn_attack_span(Them, s + pawn_push(Us)) & ourPawns) != 0 - && popcount(b) >= popcount(pawn_attack_span(Us, s) & theirPawns); - // Passed pawns will be properly scored in evaluation because we need // full attack info to evaluate passed pawns. Only the frontmost passed // pawn on each file is considered a true passed pawn. @@ -184,33 +165,20 @@ namespace { value -= UnsupportedPawnPenalty; if (doubled) - value -= Doubled[f] / rank_distance(s, lsb(doubled)); + value -= Doubled[f] / distance(s, frontmost_sq(Us, doubled)); if (backward) value -= Backward[opposed][f]; if (connected) - value += Connected[f][relative_rank(Us, s)]; + value += Connected[opposed][phalanx][relative_rank(Us, s)]; if (lever) - value += Lever[relative_rank(Us, s)]; - - if (candidate) - { - value += CandidatePassed[relative_rank(Us, s)]; - - if (!doubled) - e->candidatePawns[Us] |= s; - } + value += Lever[relative_rank(Us, s)]; } - // In endgame it's better to have pawns on both wings. So give a bonus according - // to file distance between left and right outermost pawns. - if (pos.count(Us) > 1) - { - b = e->semiopenFiles[Us] ^ 0xFF; - value += PawnsFileSpan * int(msb(b) - lsb(b)); - } + b = e->semiopenFiles[Us] ^ 0xFF; + e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; return value; } @@ -219,18 +187,21 @@ namespace { namespace Pawns { -/// init() initializes some tables by formula instead of hard-coding their values - -void init() { - - const int bonusByFile[] = { 1, 3, 3, 4, 4, 3, 3, 1 }; - - for (Rank r = RANK_1; r < RANK_8; ++r) - for (File f = FILE_A; f <= FILE_H; ++f) - { - int bonus = r * (r - 1) * (r - 2) + bonusByFile[f] * (r / 2 + 1); - Connected[f][r] = make_score(bonus, bonus); - } +/// 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. + +void init() +{ + static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 }; + + 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); + } } @@ -297,14 +268,14 @@ 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 (!(DistanceRingsBB[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); @@ -315,7 +286,7 @@ 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