Value Entry::shelter_storm(const Position& pos, Square ksq) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard Edges = (FileABB | FileHBB) & (Rank2BB | Rank3BB);
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);
Value safety = MaxSafetyBonus;
File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (File f = kf - File(1); f <= kf + File(1); ++f)
{
b = ourPawns & file_bb(f);
Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
b = theirPawns & file_bb(f);
Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
if ( (Edges & make_square(f, rkThem))
&& file_of(ksq) == f
&& relative_rank(Us, ksq) == rkThem - 1)
safety += 200;
else
safety -= ShelterWeakness[rkUs]
+ StormDanger[rkUs == RANK_1 ? 0 :
rkThem != rkUs + 1 ? 1 : 2][rkThem];
}
return safety;
}
Value Entry::shelter_storm(const Position& pos, Square ksq) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing };
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);
Value safety = MaxSafetyBonus;
File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (File f = center - File(1); f <= center + File(1); ++f)
{
b = ourPawns & file_bb(f);
Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
b = theirPawns & file_bb(f);
Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
safety -= ShelterWeakness[std::min(f, FILE_H - f)][rkUs]
+ StormDanger
[f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing :
rkUs == RANK_1 ? NoFriendlyPawn :
rkThem == rkUs + 1 ? BlockedByPawn : Unblocked]
[std::min(f, FILE_H - f)][rkThem];
}
return safety;
}
Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
constexpr Bitboard BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB);
Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq);
Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
Value safety = (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) ?
Value(374) : Value(5);
File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (File f = File(center - 1); f <= File(center + 1); ++f)
{
b = ourPawns & file_bb(f);
int ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : 0;
b = theirPawns & file_bb(f);
int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
int d = std::min(f, ~f);
safety += ShelterStrength[d][ourRank];
safety -= (ourRank && (ourRank == theirRank - 1)) ? BlockedStorm[theirRank]
: UnblockedStorm[d][theirRank];
}
return safety;
}
// Entry::shelter_storm() calculates shelter and storm penalties for the file
// the king is on, as well as the two adjacent files.
Value Entry::shelter_storm (const Position &pos, Square k_sq)
{
const Color C_ = ((WHITE == C) ? BLACK : WHITE);
Value safety = MaxSafetyBonus;
Bitboard front_pawns = pos.pieces (PAWN) & (front_ranks_bb (C, _rank (k_sq)) | rank_bb (k_sq));
Bitboard pawns[CLR_NO] =
{
front_pawns & pos.pieces (C ),
front_pawns & pos.pieces (C_),
};
File kf = max (F_B, min (F_G, _file (k_sq)));
for (File f = kf - 1; f <= kf + 1; ++f)
{
Bitboard mid_pawns;
mid_pawns = pawns[1] & file_bb (f);
Rank b_rk = mid_pawns ? rel_rank (C, scan_rel_frntmost_sq (C_, mid_pawns)) : R_1;
if ((MID_EDGE_bb & (f | b_rk)) &&
_file (k_sq) == f &&
rel_rank (C, k_sq) == b_rk - 1)
{
safety += Value (200);
}
else
{
mid_pawns = pawns[0] & file_bb (f);
Rank w_rk = mid_pawns ? rel_rank (C, scan_rel_backmost_sq (C , mid_pawns)) : R_1;
int8_t danger = (w_rk != R_1) ? ((b_rk == w_rk + 1) ? 2 : 1) : 0;
safety -= ShelterWeakness[w_rk]
+ StormDanger[danger][b_rk];
}
}
return safety;
}
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, rank_of(ksq)) | rank_bb(ksq));
Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
Rank rkUs, rkThem;
File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (File f = kf - File(1); f <= kf + File(1); ++f)
{
b = ourPawns & file_bb(f);
rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
safety -= ShelterWeakness[rkUs];
b = theirPawns & file_bb(f);
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;
}
