// evaluate_passed_pawns() evaluates the passed pawns of the given color
template<Color Us>
- void evaluate_passed_pawns_of_color(const Position& pos, bool hasUnstoppable[], int movesToGo[], EvalInfo& ei) {
+ void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
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)
+ if (tr)
{
+ Square blockSq = s + pawn_push(Us);
+
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))
{
+ // There are no enemy pawns in the pawn's path
b2 = squares_in_front_of(Us, s);
- b3 = b2 & ei.attacked_by(Them);
+
+ assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
+
+ // Squares attacked by us
b4 = b2 & ei.attacked_by(Us);
+ // Squares attacked or occupied by enemy pieces
+ b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
+
// If there is an enemy rook or queen attacking the pawn from behind,
// add all X-ray attacks by the rook or queen.
if ( bit_is_set(ei.attacked_by(Them, ROOK) | ei.attacked_by(Them, QUEEN), s)
&& (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them)))
b3 = b2;
- // Squares attacked or occupied by enemy pieces
- b3 |= (b2 & pos.pieces_of_color(Them));
-
- // There are no enemy pawns in the pawn's path
- assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
-
// 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));
else
// OK, there are enemy attacks or pieces (but not pawns). Are those
- // squares which are attacked by the enemy also attacked by us?
+ // 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));
mtg += blockerCount;
d += blockerCount;
if (d < 0)
- {
- hasUnstoppable[Us] = true;
- movesToGo[Us] = Min(movesToGo[Us], mtg);
- }
+ movesToGo[Us] = movesToGo[Us] ? Min(movesToGo[Us], mtg) : mtg;
}
}
void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
- bool hasUnstoppable[2] = {false, false};
- int movesToGo[2] = {100, 100};
+ int movesToGo[2] = {0, 0};
// Evaluate pawns for each color
- evaluate_passed_pawns_of_color<WHITE>(pos, hasUnstoppable, movesToGo, ei);
- evaluate_passed_pawns_of_color<BLACK>(pos, hasUnstoppable, movesToGo, ei);
+ evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, ei);
+ evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, ei);
// Does either side have an unstoppable passed pawn?
- if (hasUnstoppable[WHITE] && !hasUnstoppable[BLACK])
+ if (movesToGo[WHITE] && !movesToGo[BLACK])
ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]);
- else if (hasUnstoppable[BLACK] && !hasUnstoppable[WHITE])
+ else if (movesToGo[BLACK] && !movesToGo[WHITE])
ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]);
- else if (hasUnstoppable[BLACK] && hasUnstoppable[WHITE])
+ else if (movesToGo[BLACK] && movesToGo[WHITE])
{
// Both sides have unstoppable pawns! Try to find out who queens
// first. We begin by transforming 'movesToGo' to the number of