};
// Assorted bonuses and penalties
+ constexpr Score AttacksOnSpaceArea = S( 4, 0);
constexpr Score BishopPawns = S( 3, 7);
constexpr Score CorneredBishop = S( 50, 50);
constexpr Score FlankAttacks = S( 8, 0);
// color, including x-rays. But diagonal x-rays through pawns are not computed.
Bitboard attackedBy2[COLOR_NB];
- // kingRing[color] are the squares adjacent to the king, plus (only for a
- // king on its first rank) the squares two ranks in front. For instance,
- // if black's king is on g8, kingRing[BLACK] is f8, h8, f7, g7, h7, f6, g6
- // and h6.
+ // kingRing[color] are the squares adjacent to the king plus some other
+ // very near squares, depending on king position.
Bitboard kingRing[COLOR_NB];
// kingAttackersCount[color] is the number of pieces of the given color
// If the pawn is free to advance, then increase the bonus
if (pos.empty(blockSq))
{
- // If there is a rook or queen attacking/defending the pawn from behind,
- // consider all the squaresToQueen. Otherwise consider only the squares
- // in the pawn's path attacked or occupied by the enemy.
- defendedSquares = unsafeSquares = squaresToQueen = forward_file_bb(Us, s);
+ defendedSquares = squaresToQueen = forward_file_bb(Us, s);
+ unsafeSquares = passed_pawn_span(Us, s);
bb = forward_file_bb(Them, s) & pos.pieces(ROOK, QUEEN);
if (!(pos.pieces(Them) & bb))
unsafeSquares &= attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
- // If there aren't any enemy attacks, assign a big bonus. Otherwise
- // assign a smaller bonus if the block square isn't attacked.
- int k = !unsafeSquares ? 20 : !(unsafeSquares & blockSq) ? 9 : 0;
+ // If there are no enemy attacks on passed pawn span, assign a big bonus.
+ // Otherwise assign a smaller bonus if the path to queen is not attacked
+ // and even smaller bonus if it is attacked but block square is not.
+ int k = !unsafeSquares ? 35 :
+ !(unsafeSquares & squaresToQueen) ? 20 :
+ !(unsafeSquares & blockSq) ? 9 :
+ 0 ;
// Assign a larger bonus if the block square is defended.
if (defendedSquares & blockSq)
int weight = pos.count<ALL_PIECES>(Us) - 1;
Score score = make_score(bonus * weight * weight / 16, 0);
+ score -= AttacksOnSpaceArea * popcount(attackedBy[Them][ALL_PIECES] & behind & safe);
+
if (T)
Trace::add(SPACE, Us, score);
// Early exit if score is high
Value v = (mg_value(score) + eg_value(score)) / 2;
- if (abs(v) > (LazyThreshold + pos.non_pawn_material() / 64))
+ if (abs(v) > LazyThreshold + pos.non_pawn_material() / 64)
return pos.side_to_move() == WHITE ? v : -v;
// Main evaluation begins here