const Color Them = (Us == WHITE ? BLACK : WHITE);
+ Bitboard squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us);
while (b)
Value mbonus = Value(20 * tr);
Value ebonus = Value(10 + r * r * 10);
- // Adjust bonus based on king proximity
if (tr)
{
Square blockSq = s + pawn_push(Us);
+ // Adjust bonus based on kings proximity
ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * tr);
ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * tr);
ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
// If the pawn is free to advance, increase bonus
if (pos.square_is_empty(blockSq))
{
- // There are no enemy pawns in the pawn's path
- Bitboard b2 = squares_in_front_of(Us, s);
-
- assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
-
- // Squares attacked by us
- Bitboard b4 = b2 & ei.attacked_by(Us);
+ squaresToQueen = squares_in_front_of(Us, s);
+ defendedSquares = squaresToQueen & ei.attacked_by(Us);
- // Squares attacked or occupied by enemy pieces
- Bitboard b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
+ // There are no enemy pawns in the pawn's path
+ assert(!(squaresToQueen & pos.pieces(PAWN, Them)));
// If there is an enemy rook or queen attacking the pawn from behind,
- // add all X-ray attacks by the rook or queen.
+ // add all X-ray attacks by the rook or queen. Otherwise consider only
+ // the squares in the pawn's path attacked or occupied by the enemy.
if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
&& (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
- b3 = b2;
+ unsafeSquares = squaresToQueen;
+ else
+ unsafeSquares = squaresToQueen & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
- // Are any of the squares in the pawn's path attacked or occupied by the enemy?
- if (b3 == EmptyBoardBB)
- // No enemy attacks or pieces, huge bonus!
- // Even bigger if we protect the pawn's path
- ebonus += Value(tr * (b2 == b4 ? 17 : 15));
+ // If there aren't enemy attacks or pieces along the path to queen give
+ // huge bonus. Even bigger if we protect the pawn's path.
+ if (!unsafeSquares)
+ ebonus += Value(tr * (squaresToQueen == defendedSquares ? 17 : 15));
else
// OK, there are enemy attacks or pieces (but not pawns). Are those
// squares which are attacked by the enemy also attacked by us ?
// If yes, big bonus (but smaller than when there are no enemy attacks),
// if no, somewhat smaller bonus.
- ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
+ ebonus += Value(tr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
// At last, add a small bonus when there are no *friendly* pieces
// in the pawn's path.
- if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
+ if (!(squaresToQueen & pos.pieces_of_color(Us)))
ebonus += Value(tr);
}
} // tr != 0
- // If the pawn is supported by a friendly pawn, increase bonus
- Bitboard b1 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
- if (b1 & rank_bb(s))
+ // Increase the bonus if the passed pawn is supported by a friendly pawn
+ // on the same rank and a bit smaller if it's on the previous rank.
+ supportingPawns = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
+ if (supportingPawns & rank_bb(s))
ebonus += Value(r * 20);
- else if (pos.attacks_from<PAWN>(s, Them) & b1)
+ else if (supportingPawns & rank_bb(s - pawn_push(Us)))
ebonus += Value(r * 12);
// Rook pawns are a special case: They are sometimes worse, and
// Find the safe squares for our pieces inside the area defined by
// SpaceMask[us]. A square is unsafe if it is attacked by an enemy
// pawn, or if it is undefended and attacked by an enemy piece.
-
Bitboard safeSquares = SpaceMask[Us]
& ~pos.pieces(PAWN, Us)
& ~ei.attacked_by(Them, PAWN)
- & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
+ & (ei.attacked_by(Us) | ~ei.attacked_by(Them));
- // Find all squares which are at most three squares behind some friendly
- // pawn.
+ // Find all squares which are at most three squares behind some friendly pawn
Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 8 : behindFriendlyPawns << 8);
behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
- Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
-
- // Convert to integer to prevent overflow
- int mg = mg_value(uciWeight);
- int eg = eg_value(uciWeight);
+ // Scale option value from 100 to 256
+ int mg = get_option_value_int(mgOpt) * 256 / 100;
+ int eg = get_option_value_int(egOpt) * 256 / 100;
- mg = (mg * 0x100) / 100;
- eg = (eg * 0x100) / 100;
- mg = (mg * mg_value(internalWeight)) / 0x100;
- eg = (eg * eg_value(internalWeight)) / 0x100;
- return make_score(mg, eg);
+ return apply_weight(make_score(mg, eg), internalWeight);
}
// init_safety() initizes the king safety evaluation, based on UCI
void init_safety() {
- int maxSlope = 30;
- int peak = 0x500;
- double a = 0.4;
- double b = 0.0;
+ const Value MaxSlope = Value(30);
+ const Value Peak = Value(1280);
Value t[100];
// First setup the base table
for (int i = 0; i < 100; i++)
{
- if (i < b)
- t[i] = Value(0);
- else
- t[i] = Value((int)(a * (i - b) * (i - b)));
- }
+ t[i] = Value(int(0.4 * i * i));
- for (int i = 1; i < 100; i++)
- {
- if (t[i] - t[i - 1] > maxSlope)
- t[i] = t[i - 1] + Value(maxSlope);
+ if (i > 0)
+ t[i] = Min(t[i], t[i - 1] + MaxSlope);
- if (t[i] > Value(peak))
- t[i] = Value(peak);
+ t[i] = Min(t[i], Peak);
}
// Then apply the weights and get the final KingDangerTable[] array