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;
}
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 (int f = kf - 1; f <= kf + 1; f++)
{
b = ourPawns & FileBB[f];
rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
safety -= ShelterWeakness[rkUs];
b = theirPawns & FileBB[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;
}
Value Eval::evaluate(const Position& pos) {
assert(!pos.checkers());
EvalInfo ei;
Score score, mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
// Initialize score by reading the incrementally updated scores included in
// the position object (material + piece square tables). Score is computed
// internally from the white point of view.
score = pos.psq_score();
// Probe the material hash table
ei.me = Material::probe(pos);
score += ei.me->imbalance();
// If we have a specialized evaluation function for the current material
// configuration, call it and return.
if (ei.me->specialized_eval_exists())
return ei.me->evaluate(pos);
// Probe the pawn hash table
ei.pi = Pawns::probe(pos);
score += ei.pi->pawns_score();
// Initialize attack and king safety bitboards
ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
eval_init<WHITE>(pos, ei);
eval_init<BLACK>(pos, ei);
// Pawns blocked or on ranks 2 and 3 will be excluded from the mobility area
Bitboard blockedPawns[] = {
pos.pieces(WHITE, PAWN) & (shift_bb<DELTA_S>(pos.pieces()) | Rank2BB | Rank3BB),
pos.pieces(BLACK, PAWN) & (shift_bb<DELTA_N>(pos.pieces()) | Rank7BB | Rank6BB)
};
// Do not include in mobility area squares protected by enemy pawns, or occupied
// by our blocked pawns or king.
Bitboard mobilityArea[] = {
~(ei.attackedBy[BLACK][PAWN] | blockedPawns[WHITE] | pos.square<KING>(WHITE)),
~(ei.attackedBy[WHITE][PAWN] | blockedPawns[BLACK] | pos.square<KING>(BLACK))
};
// Evaluate all pieces but king and pawns
score += evaluate_pieces<DoTrace>(pos, ei, mobility, mobilityArea);
score += mobility[WHITE] - mobility[BLACK];
// Evaluate kings after all other pieces because we need full attack
// information when computing the king safety evaluation.
score += evaluate_king<WHITE, DoTrace>(pos, ei)
- evaluate_king<BLACK, DoTrace>(pos, ei);
// Evaluate tactical threats, we need full attack information including king
score += evaluate_threats<WHITE, DoTrace>(pos, ei)
- evaluate_threats<BLACK, DoTrace>(pos, ei);
// Evaluate passed pawns, we need full attack information including king
score += evaluate_passed_pawns<WHITE, DoTrace>(pos, ei)
- evaluate_passed_pawns<BLACK, DoTrace>(pos, ei);
// If both sides have only pawns, score for potential unstoppable pawns
if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
{
Bitboard b;
if ((b = ei.pi->passed_pawns(WHITE)) != 0)
score += Unstoppable * int(relative_rank(WHITE, frontmost_sq(WHITE, b)));
if ((b = ei.pi->passed_pawns(BLACK)) != 0)
score -= Unstoppable * int(relative_rank(BLACK, frontmost_sq(BLACK, b)));
}
// Evaluate space for both sides, only during opening
if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
score += evaluate_space<WHITE>(pos, ei)
- evaluate_space<BLACK>(pos, ei);
// Evaluate position potential for the winning side
score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
// Evaluate scale factor for the winning side
ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
// Interpolate between a middlegame and a (scaled by 'sf') endgame score
Value v = mg_value(score) * int(ei.me->game_phase())
+ eg_value(score) * int(PHASE_MIDGAME - ei.me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
v /= int(PHASE_MIDGAME);
// In case of tracing add all remaining individual evaluation terms
if (DoTrace)
{
Trace::add(MATERIAL, pos.psq_score());
Trace::add(IMBALANCE, ei.me->imbalance());
Trace::add(PAWN, ei.pi->pawns_score());
Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)
, evaluate_space<BLACK>(pos, ei));
Trace::add(TOTAL, score);
}
return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
}
