X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=b83b780ab00f21e8228889e8ea13c358d0ce2939;hp=626f2b57bd82958671cdbb6b2d1e9a845d255331;hb=ace8e951d70c2986a0af83effcc0d2b2312d29e3;hpb=6a79d5d10eb4313fd71abe249a64aaed6bba1e67 diff --git a/src/pawns.cpp b/src/pawns.cpp index 626f2b57..b83b780a 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -2,6 +2,7 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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 @@ -21,7 +22,6 @@ #include #include "bitboard.h" -#include "bitcount.h" #include "pawns.h" #include "position.h" #include "thread.h" @@ -31,34 +31,26 @@ 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(37, 45), S(54, 52), S(60, 52), S(60, 52), - S(60, 52), S(60, 52), S(54, 52), S(37, 45) }, - { S(25, 30), S(36, 35), S(40, 35), S(40, 35), - S(40, 35), S(40, 35), S(36, 35), S(25, 30) } }; + // 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(67, 42), S(49, 24) }; - - // Unsupported pawn penalty, for pawns which are neither isolated or backward - const Score Unsupported = S(20, 10); + const Score Backward[2] = { S(56, 33), S(41, 19) }; + + // Unsupported pawn penalty for pawns which are neither isolated or backward, + // by number of pawns it supports [less than 2 / exactly 2]. + const Score Unsupported[2] = { S(17, 8), S(21, 12) }; // 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(13, 43), S(20, 48), S(23, 48), S(23, 48), - S(23, 48), S(23, 48), S(20, 48), S(13, 43) }; + + // Doubled pawn penalty + const Score Doubled = S(18,38); // Lever 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) }; - - // Center bind bonus, when two pawns controls the same central square - const Score CenterBind = S(16, 0); + S(17, 16), S(33, 32), S(0, 0), S(0, 0) }; // Weakness of our pawn shelter in front of the king by [distance from edge][rank] const Value ShelterWeakness[][RANK_NB] = { @@ -101,13 +93,9 @@ namespace { const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); - const Bitboard CenterBindMask = - Us == WHITE ? (FileDBB | FileEBB) & (Rank5BB | Rank6BB | Rank7BB) - : (FileDBB | FileEBB) & (Rank4BB | Rank3BB | Rank2BB); - - 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)]; @@ -119,7 +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 @@ -133,72 +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)); - assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns)); + // 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(!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; + 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; - - b = shift_bb(ourPawns) & shift_bb(ourPawns) & CenterBindMask; - score += CenterBind * popcount(b); - return score; } @@ -212,7 +185,7 @@ namespace Pawns { void init() { - static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 }; + static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 }; for (int opposed = 0; opposed <= 1; ++opposed) for (int phalanx = 0; phalanx <= 1; ++phalanx) @@ -221,7 +194,7 @@ void init() { 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); + Connected[opposed][phalanx][apex][r] = make_score(v, v * 5 / 8); } } @@ -241,7 +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; } @@ -296,9 +270,6 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) { if (pawns) while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} - if (relative_rank(Us, ksq) > RANK_4) - return make_score(0, -16 * minKingPawnDistance); - Value bonus = shelter_storm(pos, ksq); // If we can castle use the bonus after the castling if it is bigger