X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=b83b780ab00f21e8228889e8ea13c358d0ce2939;hp=9239bface2e06c163b6daa521e9ba8fe3f6a9bd5;hb=b96dd754ede60b8463606cf38eac3eab400a123d;hpb=5d1644ba696c0a4d81450f922d216bf6479d4929 diff --git a/src/pawns.cpp b/src/pawns.cpp index 9239bfac..b83b780a 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -22,7 +22,6 @@ #include #include "bitboard.h" -#include "bitcount.h" #include "pawns.h" #include "position.h" #include "thread.h" @@ -32,12 +31,8 @@ namespace { #define V Value #define S(mg, eg) make_score(mg, eg) - // Isolated pawn penalty by opposed flag and file - const Score Isolated[2][FILE_NB] = { - { S(31, 36), S(45, 41), S(50, 41), S(50, 41), - S(50, 41), S(50, 41), S(45, 41), S(31, 36) }, - { S(21, 24), S(30, 28), S(33, 28), S(33, 28), - S(33, 28), S(33, 28), S(30, 28), S(21, 24) } }; + // Isolated pawn penalty by opposed flag + const Score Isolated[2] = { S(45, 40), S(30, 27) }; // Backward pawn penalty by opposed flag const Score Backward[2] = { S(56, 33), S(41, 19) }; @@ -49,10 +44,8 @@ namespace { // Connected pawn bonus by opposed, phalanx, twice supported and rank Score Connected[2][2][2][RANK_NB]; - // Doubled pawn penalty by file - const Score Doubled[FILE_NB] = { - S(11, 34), S(17, 38), S(19, 38), S(19, 38), - S(19, 38), S(19, 38), S(17, 38), S(11, 34) }; + // Doubled pawn penalty + const Score Doubled = S(18,38); // Lever bonus by rank const Score Lever[RANK_NB] = { @@ -100,9 +93,9 @@ namespace { const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); - Bitboard b, neighbours, doubled, supported, phalanx; + Bitboard b, neighbours, stoppers, doubled, supported, phalanx; Square s; - bool passed, isolated, opposed, backward, lever, connected; + bool opposed, lever, connected, backward; Score score = SCORE_ZERO; const Square* pl = pos.squares(Us); const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)]; @@ -114,7 +107,7 @@ namespace { 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][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 @@ -128,69 +121,57 @@ namespace { e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); // Flag the pawn - neighbours = ourPawns & adjacent_files_bb(f); - doubled = ourPawns & forward_bb(Us, s); - opposed = theirPawns & forward_bb(Us, s); - passed = !(theirPawns & passed_pawn_mask(Us, s)); - lever = theirPawns & pawnAttacksBB[s]; - phalanx = neighbours & rank_bb(s); - supported = neighbours & rank_bb(s - Up); - connected = supported | phalanx; - isolated = !neighbours; - - // Test for backward pawn. - // If the pawn is passed, isolated, lever or connected it cannot be - // backward. If there are friendly pawns behind on adjacent files - // or if it is sufficiently advanced, it cannot be backward either. - if ( (passed | isolated | lever | connected) - || (ourPawns & pawn_attack_span(Them, s)) - || (relative_rank(Us, s) >= RANK_5)) + opposed = theirPawns & forward_bb(Us, s); + stoppers = theirPawns & passed_pawn_mask(Us, s); + lever = theirPawns & pawnAttacksBB[s]; + doubled = ourPawns & (s + Up); + neighbours = ourPawns & adjacent_files_bb(f); + phalanx = neighbours & rank_bb(s); + supported = neighbours & rank_bb(s - Up); + connected = supported | phalanx; + + // A pawn is backward when it is behind all pawns of the same color on the + // adjacent files and cannot be safely advanced. + if (!neighbours || lever || relative_rank(Us, s) >= RANK_5) backward = false; else { - // 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. - b = pawn_attack_span(Us, s) & (ourPawns | theirPawns); - b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b)); - - // 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; - } + // Find the backmost rank with neighbours or stoppers + b = rank_bb(backmost_sq(Us, neighbours | stoppers)); + + // The pawn is backward when it cannot safely progress to that rank: + // either there is a stopper in the way on this rank, or there is a + // stopper on adjacent file which controls the way to that rank. + backward = (b | shift_bb(b & adjacent_files_bb(f))) & stoppers; - assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns)); + assert(!backward || !(pawn_attack_span(Them, s + Up) & neighbours)); + } // Passed pawns will be properly scored in evaluation because we need - // full attack info to evaluate them. Only the frontmost passed - // pawn on each file is considered a true passed pawn. - if (passed && !doubled) + // full attack info to evaluate them. + if (!stoppers && !(ourPawns & forward_bb(Us, s))) e->passedPawns[Us] |= s; // Score this pawn - if (isolated) - score -= Isolated[opposed][f]; + if (!neighbours) + score -= Isolated[opposed]; else if (backward) score -= Backward[opposed]; else if (!supported) - score -= Unsupported[more_than_one(neighbours & rank_bb(s + Up))]; + score -= Unsupported[more_than_one(neighbours & pawnAttacksBB[s])]; if (connected) score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)]; if (doubled) - score -= Doubled[f] / distance(s, frontmost_sq(Us, doubled)); + score -= Doubled; if (lever) score += Lever[relative_rank(Us, s)]; } - b = e->semiopenFiles[Us] ^ 0xFF; - e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; - return score; } @@ -233,7 +214,8 @@ Entry* probe(const Position& pos) { e->key = key; e->score = evaluate(pos, e) - evaluate(pos, e); - e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]); + e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]); + e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]); return e; }