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Rewrite pawn shield and storm code

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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
This commit is contained in:
Tom Vijlbrief 2013-07-25 22:23:15 +02:00 • committed by Marco Costalba
parent 2067a99c07
commit 7487eb0dca
1 changed files with 14 additions and 15 deletions
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29
src/pawns.cpp
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@ -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;