From 7487eb0dcae93731330f06c7d289ca156487a16f Mon Sep 17 00:00:00 2001 From: Tom Vijlbrief Date: Thu, 25 Jul 2013 22:23:15 +0200 Subject: [PATCH] Rewrite pawn shield and storm code Passes quickly both short TC: LLR: 2.95 (-2.94,2.94) Total: 5755 W: 1349 L: 1222 D: 3184 And long TC: LLR: 2.95 (-2.94,2.94) Total: 2744 W: 628 L: 505 D: 1611 bench: 4727133 --- src/pawns.cpp | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff --git a/src/pawns.cpp b/src/pawns.cpp index 135633a3..74aa0e0d 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -63,15 +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. @@ -222,7 +223,7 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { Value safety = MaxSafetyBonus; Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); - Bitboard ourPawns = b & pos.pieces(Us) & ~rank_bb(ksq); + Bitboard ourPawns = b & pos.pieces(Us); Bitboard theirPawns = b & pos.pieces(Them); Rank rkUs, rkThem; File kf = file_of(ksq); @@ -231,15 +232,13 @@ Value Entry::shelter_storm(const Position& pos, Square 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, Us == WHITE ? lsb(b) : msb(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, Us == WHITE ? lsb(b) : msb(b)) : RANK_1; + safety -= StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem]; } return safety; -- 2.39.2