- for(Color us = WHITE; us <= BLACK; us++) {
- Color them = opposite_color(us);
- Square ourKingSq = pos.king_square(us);
- Square theirKingSq = pos.king_square(them);
- Bitboard b = ei.pi->passed_pawns() & pos.pawns(us), b2, b3, b4;
-
- while(b) {
- Square s = pop_1st_bit(&b);
- assert(pos.piece_on(s) == pawn_of_color(us));
- assert(pos.pawn_is_passed(us, s));
-
- int r = int(relative_rank(us, s) - RANK_2);
- int tr = Max(0, r * (r-1));
- Square blockSq = s + pawn_push(us);
-
- // Base bonus based on rank:
- Value mbonus = Value(20 * tr);
- Value ebonus = Value(10 + r * r * 10);
-
- // Adjust bonus based on king proximity:
- ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
- ebonus -=
- Value(square_distance(ourKingSq, blockSq + pawn_push(us)) * 1 * tr);
- ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
-
- // If the pawn is free to advance, increase bonus:
- if(pos.square_is_empty(blockSq)) {
-
- b2 = squares_in_front_of(us, s);
- b3 = b2 & ei.attacked_by(them);
- b4 = b2 & ei.attacked_by(us);
- if((b2 & pos.pieces_of_color(them)) == EmptyBoardBB) {
- // There are no enemy pieces in the pawn's path! Are any of the
- // squares in the pawn's path attacked by the enemy?
- if(b3 == EmptyBoardBB)
- // No enemy attacks, huge bonus!
- ebonus += Value(tr * ((b2 == b4)? 17 : 15));
- else
- // OK, there are enemy attacks. 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));
- }
- else {
- // There are some enemy pieces in the pawn's path. While this is
- // sad, we still assign a moderate bonus if all squares in the path
- // which are either occupied by or attacked by enemy pieces are
- // also attacked by us.
- if(((b3 | (b2 & pos.pieces_of_color(them))) & ~b4) == EmptyBoardBB)
- ebonus += Value(tr * 6);
- }
- // 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)
- ebonus += Value(tr);
- }
+ for (Color us = WHITE; us <= BLACK; us++)
+ {
+ Color them = opposite_color(us);
+ Square ourKingSq = pos.king_square(us);
+ Square theirKingSq = pos.king_square(them);
+ Bitboard b = ei.pi->passed_pawns() & pos.pawns(us), b2, b3, b4;
+
+ while (b)
+ {
+ Square s = pop_1st_bit(&b);
+
+ assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN));
+ assert(pos.pawn_is_passed(us, s));
+
+ int r = int(relative_rank(us, s) - RANK_2);
+ int tr = Max(0, r * (r - 1));
+ Square blockSq = s + pawn_push(us);
+
+ // Base bonus based on rank
+ Value mbonus = Value(20 * tr);
+ Value ebonus = Value(10 + r * r * 10);
+
+ // Adjust bonus based on king proximity
+ if (tr != 0)
+ {
+ ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
+ ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(us)) * 1 * tr);
+ ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
+
+ // If the pawn is free to advance, increase bonus
+ if (pos.square_is_empty(blockSq))
+ {
+ b2 = squares_in_front_of(us, s);
+ b3 = b2 & ei.attacked_by(them);
+ b4 = b2 & ei.attacked_by(us);