X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=d6ea1479de80c407449863709208db76fa1b13c3;hp=4693e1584f5b2161573fd42ff19643791feeef20;hb=f6d220ab145a361f7240a44dbe61056e801d9bda;hpb=069073ea6882ccb27fe4b571ed08ebe6a4ad8c65 diff --git a/src/pawns.cpp b/src/pawns.cpp index 4693e158..d6ea1479 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -49,17 +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 bonus by rank - const int Connected[RANK_NB] = {0, 6, 15, 10, 57, 75, 135, 258}; + // 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); @@ -68,11 +65,14 @@ namespace { { 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) } }; + // [edge files][no friendly pawn | pawn unblocked | pawn blocked][rank of enemy pawn] + const Value StormDanger[][3][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) } }, + { { 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( 80), V(13), V( 7) } } }; // 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. @@ -89,9 +89,9 @@ 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; - bool passed, isolated, opposed, connected, backward, 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)]; @@ -111,7 +111,6 @@ namespace { { assert(pos.piece_on(s) == make_piece(Us, PAWN)); - Rank r = rank_of(s), rr = relative_rank(Us, s); File f = file_of(s); // This file cannot be semi-open @@ -120,12 +119,10 @@ 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); @@ -171,29 +168,21 @@ 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) { - int bonus = Connected[rr]; - if (ourPawns & adjacent_files_bb(f) & rank_bb(r)) - bonus += (Connected[rr+1] - Connected[rr]) / 2; - value += make_score(bonus / 2, bonus >> opposed); - } + if (connected) + value += Connected[opposed][phalanx][relative_rank(Us, s)]; if (lever) - value += Lever[rr]; + value += Lever[relative_rank(Us, s)]; } b = e->semiopenFiles[Us] ^ 0xFF; e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; - // 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. - value += PawnsFileSpan * e->pawnSpan[Us]; - return value; } @@ -201,6 +190,24 @@ 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. + +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); + } +} + + /// 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. @@ -248,7 +255,8 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { safety += 200; else safety -= ShelterWeakness[rkUs] - + StormDanger[rkUs == RANK_1 ? 0 : + + StormDanger[f == FILE_A || f == FILE_H] + [rkUs == RANK_1 ? 0 : rkThem != rkUs + 1 ? 1 : 2][rkThem]; } @@ -264,14 +272,14 @@ 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); @@ -282,7 +290,7 @@ 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