X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=d65b0418f0145f448c3d37dff8ecb7262c86fdaf;hp=280c1fd6a99e569bcbb9ac4c633e6fd50a0f088e;hb=49e110c52b19f5c99954d4797b8e991b0b60007c;hpb=46409a7852ae22abf9c32cbcfe3b35f164ae8ec5 diff --git a/src/pawns.cpp b/src/pawns.cpp index 280c1fd6..d65b0418 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -17,6 +17,7 @@ along with this program. If not, see . */ +#include #include #include "bitboard.h" @@ -62,15 +63,16 @@ namespace { S(34,68), S(83,166), S(0, 0), S( 0, 0) }; - // Weakness of our pawn shelter in front of the king indexed by [king pawn][rank] - const Value ShelterWeakness[2][RANK_NB] = - { { V(141), V(0), V(38), V(102), V(128), V(141), V(141) }, - { V( 61), V(0), V(16), V( 44), V( 56), V( 61), V( 61) } }; + // 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 [pawn blocked][rank] - const Value StormDanger[2][RANK_NB] = - { { V(26), V(0), V(128), V(51), V(26) }, - { V(13), V(0), V( 64), V(25), V(13) } }; + // Danger of enemy pawns moving toward our king indexed by + // [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( 64), V(25), V(13) }}; // Max bonus for king safety. Corresponds to start position with all the pawns // in front of the king and no enemy pawn on the horizont. @@ -80,18 +82,29 @@ namespace { #undef V template - Score evaluate_pawns(const Position& pos, Bitboard ourPawns, - Bitboard theirPawns, Pawns::Entry* e) { + Score evaluate(const Position& pos, Pawns::Entry* e) { - const Color Them = (Us == WHITE ? BLACK : WHITE); + const Color Them = (Us == WHITE ? BLACK : WHITE); + const Square Up = (Us == WHITE ? DELTA_N : DELTA_S); + const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); + const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); Bitboard b; Square s; File f; - Rank r; bool passed, isolated, doubled, opposed, chain, backward, candidate; Score value = SCORE_ZERO; - const Square* pl = pos.piece_list(Us, PAWN); + const Square* pl = pos.list(Us); + + Bitboard ourPawns = pos.pieces(Us, PAWN); + Bitboard theirPawns = pos.pieces(Them, PAWN); + + e->passedPawns[Us] = 0; + e->kingSquares[Us] = SQ_NONE; + e->semiopenFiles[Us] = 0xFF; + e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns); + e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares); + e->pawnsOnSquares[Us][WHITE] = pos.count(Us) - e->pawnsOnSquares[Us][BLACK]; // Loop through all pawns of the current color and score each pawn while ((s = *pl++) != SQ_NONE) @@ -99,13 +112,12 @@ namespace { assert(pos.piece_on(s) == make_piece(Us, PAWN)); f = file_of(s); - r = rank_of(s); // This file cannot be semi-open e->semiopenFiles[Us] &= ~(1 << f); // Our rank plus previous one. Used for chain detection - b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1)); + b = rank_bb(s) | rank_bb(s - pawn_push(Us)); // Flag the pawn as passed, isolated, doubled or member of a pawn // chain (but not the backward one). @@ -115,41 +127,37 @@ namespace { opposed = theirPawns & forward_bb(Us, s); passed = !(theirPawns & passed_pawn_mask(Us, s)); - // Test for backward pawn - backward = false; - + // Test for backward pawn. // If the pawn is passed, isolated, or member of a pawn chain it cannot // be backward. If there are friendly pawns behind on adjacent files // or if can capture an enemy pawn it cannot be backward either. - if ( !(passed | isolated | chain) - && !(ourPawns & attack_span_mask(Them, s)) - && !(pos.attacks_from(s, Us) & theirPawns)) + if ( (passed | isolated | chain) + || (ourPawns & pawn_attack_span(Them, s)) + || (pos.attacks_from(s, Us) & theirPawns)) + backward = false; + else { // We now know that 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 seeing whether we meet a friendly or an enemy pawn first. - b = pos.attacks_from(s, Us); + // files, and picking the closest pawn there. + b = pawn_attack_span(Us, s) & (ourPawns | theirPawns); + b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b)); - // Note that we are sure to find something because pawn is not passed - // nor isolated, so loop is potentially infinite, but it isn't. - while (!(b & (ourPawns | theirPawns))) - Us == WHITE ? b <<= 8 : b >>= 8; - - // The friendly pawn needs to be at least two ranks closer than the - // enemy pawn in order to help the potentially backward pawn advance. - backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns; + // If we have an enemy pawn in the same or next rank, the pawn is + // backward because it cannot advance without being captured. + backward = (b | shift_bb(b)) & theirPawns; } - assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns)); + 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 or equal than the number of // enemy pawns in the forward direction on the adjacent files. candidate = !(opposed | passed | backward | isolated) - && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != 0 - && popcount(b) >= popcount(attack_span_mask(Us, s) & theirPawns); + && (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 @@ -174,15 +182,10 @@ namespace { value += CandidatePassed[relative_rank(Us, s)]; } - e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & BlackSquares); - e->pawnsOnSquares[Us][WHITE] = pos.piece_count(Us, PAWN) - e->pawnsOnSquares[Us][BLACK]; - - e->pawnsOnSquares[Them][BLACK] = popcount(theirPawns & BlackSquares); - e->pawnsOnSquares[Them][WHITE] = pos.piece_count(Them, PAWN) - e->pawnsOnSquares[Them][BLACK]; - return value; } -} + +} // namespace namespace Pawns { @@ -195,24 +198,11 @@ Entry* probe(const Position& pos, Table& entries) { Key key = pos.pawn_key(); Entry* e = entries[key]; - // If e->key matches the position's pawn hash key, it means that we - // have analysed this pawn structure before, and we can simply return - // the information we found the last time instead of recomputing it. if (e->key == key) return e; e->key = key; - e->passedPawns[WHITE] = e->passedPawns[BLACK] = 0; - e->kingSquares[WHITE] = e->kingSquares[BLACK] = SQ_NONE; - e->semiopenFiles[WHITE] = e->semiopenFiles[BLACK] = 0xFF; - - Bitboard wPawns = pos.pieces(WHITE, PAWN); - Bitboard bPawns = pos.pieces(BLACK, PAWN); - e->pawnAttacks[WHITE] = ((wPawns & ~FileHBB) << 9) | ((wPawns & ~FileABB) << 7); - e->pawnAttacks[BLACK] = ((bPawns & ~FileHBB) >> 7) | ((bPawns & ~FileABB) >> 9); - - e->value = evaluate_pawns(pos, wPawns, bPawns, e) - - evaluate_pawns(pos, bPawns, wPawns, e); + e->value = evaluate(pos, e) - evaluate(pos, e); return e; } @@ -226,25 +216,21 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { const Color Them = (Us == WHITE ? BLACK : WHITE); Value safety = MaxSafetyBonus; - Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, ksq) | rank_bb(ksq)); - Bitboard ourPawns = b & pos.pieces(Us) & ~rank_bb(ksq); + 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); Rank rkUs, rkThem; - File kf = file_of(ksq); - - kf = (kf == FILE_A) ? FILE_B : (kf == FILE_H) ? FILE_G : kf; + File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); for (int f = kf - 1; f <= kf + 1; f++) { - // Shelter penalty is higher for the pawn in front of the king b = ourPawns & FileBB[f]; - rkUs = b ? rank_of(Us == WHITE ? lsb(b) : ~msb(b)) : RANK_1; - safety -= ShelterWeakness[f != kf][rkUs]; + rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; + safety -= ShelterWeakness[rkUs]; - // Storm danger is smaller if enemy pawn is blocked b = theirPawns & FileBB[f]; - rkThem = b ? rank_of(Us == WHITE ? lsb(b) : ~msb(b)) : RANK_1; - safety -= StormDanger[rkThem == rkUs + 1][rkThem]; + rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; + safety -= StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem]; } return safety;