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Small evaluate_passed_pawns() cleanup

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Mainly renamed local variables with sensible names.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-05-10 12:27:33 +02:00
parent c053f0b838
commit 2aa455ce95
1 changed files with 22 additions and 23 deletions
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45
src/evaluate.cpp
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@ -788,6 +788,7 @@ namespace {
const Color Them = (Us == WHITE ? BLACK : WHITE); const Color Them = (Us == WHITE ? BLACK : WHITE);
Bitboard squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us); Bitboard b = ei.pi->passed_pawns() & pos.pieces_of_color(Us);
while (b) while (b)
@ -804,11 +805,11 @@ namespace {
Value mbonus = Value(20 * tr); Value mbonus = Value(20 * tr);
Value ebonus = Value(10 + r * r * 10); Value ebonus = Value(10 + r * r * 10);
// Adjust bonus based on king proximity
if (tr) if (tr)
{ {
Square blockSq = s + pawn_push(Us); 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) * 3 * tr);
ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * 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); ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
@ -816,47 +817,45 @@ namespace {
// If the pawn is free to advance, increase bonus // If the pawn is free to advance, increase bonus
if (pos.square_is_empty(blockSq)) if (pos.square_is_empty(blockSq))
{ {
squaresToQueen = squares_in_front_of(Us, s);
defendedSquares = squaresToQueen & ei.attacked_by(Us);
// There are no enemy pawns in the pawn's path // There are no enemy pawns in the pawn's path
Bitboard b2 = squares_in_front_of(Us, s); assert(!(squaresToQueen & pos.pieces(PAWN, Them)));
assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
// Squares attacked by us
Bitboard b4 = b2 & ei.attacked_by(Us);
// Squares attacked or occupied by enemy pieces
Bitboard b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
// If there is an enemy rook or queen attacking the pawn from behind, // 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)) if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
&& (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s))) && (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 there aren't enemy attacks or pieces along the path to queen give
if (b3 == EmptyBoardBB) // huge bonus. Even bigger if we protect the pawn's path.
// No enemy attacks or pieces, huge bonus! if (!unsafeSquares)
// Even bigger if we protect the pawn's path ebonus += Value(tr * (squaresToQueen == defendedSquares ? 17 : 15));
ebonus += Value(tr * (b2 == b4 ? 17 : 15));
else else
// OK, there are enemy attacks or pieces (but not pawns). Are those // 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 yes, big bonus (but smaller than when there are no enemy attacks),
// if no, somewhat smaller bonus. // 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 // At last, add a small bonus when there are no *friendly* pieces
// in the pawn's path. // in the pawn's path.
if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB) if (!(squaresToQueen & pos.pieces_of_color(Us)))
ebonus += Value(tr); ebonus += Value(tr);
} }
} // tr != 0 } // tr != 0
// If the pawn is supported by a friendly pawn, increase bonus // Increase the bonus if the passed pawn is supported by a friendly pawn
Bitboard b1 = pos.pieces(PAWN, Us) & neighboring_files_bb(s); // on the same rank and a bit smaller if it's on the previous rank.
if (b1 & rank_bb(s)) supportingPawns = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
if (supportingPawns & rank_bb(s))
ebonus += Value(r * 20); 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); ebonus += Value(r * 12);
// Rook pawns are a special case: They are sometimes worse, and // Rook pawns are a special case: They are sometimes worse, and