};
// Pawn storm open file bonuses by file
- const int16_t KStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 };
- const int16_t QStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 };
+ const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 };
+ const int16_t KStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 };
// Pawn storm lever bonuses by file
const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 };
/// in a hash table, so we don't have to recompute everything when the same
/// pawn structure occurs again.
-PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) {
+PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
assert(pos.is_ok());
Key key = pos.get_pawn_key();
- int index = int(key & (size - 1));
+ unsigned index = unsigned(key & (size - 1));
PawnInfo* pi = entries + index;
// If pi->key matches the position's pawn hash key, it means that we
template<Color Us>
Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, PawnInfo* pi) {
+ Bitboard theirPawns, PawnInfo* pi) const {
Bitboard b;
- Square s, s2;
+ Square s;
File f;
- Rank r, r2;
+ Rank r;
+ int bonus;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
- int bonus, v;
Score value = make_score(0, 0);
const Square* ptr = pos.piece_list_begin(Us, PAWN);
assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
- // We calculate kingside and queenside pawn storm scores for
- // both colors. These are used when evaluating middle game
- // positions with opposite side castling.
- //
- // Each pawn is given a base score given by a piece square table
- // (KStormTable[] or QStormTable[]). Pawns which seem to have good
- // chances of creating an open file by exchanging itself against
- // an enemy pawn on an adjacent file gets an additional bonus.
-
- // Kingside pawn storms
- bonus = KStormTable[relative_square(Us, s)];
- if (f >= FILE_F)
- {
- b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB);
- while (b)
- {
- // Give a bonus according to the distance of the nearest enemy pawn
- s2 = pop_1st_bit(&b);
- r2 = square_rank(s2);
- v = StormLeverBonus[f] - 2 * rank_distance(r, r2);
-
- // If enemy pawn has no pawn beside itself is particularly vulnerable.
- // Big bonus, especially against a weakness on the rook file
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- v *= (square_file(s2) == FILE_H ? 4 : 2);
-
- bonus += v;
- }
- }
- pi->ksStormValue[Us] += bonus;
+ // Calculate kingside and queenside pawn storm scores for both colors to be
+ // used when evaluating middle game positions with opposite side castling.
+ bonus = (f >= FILE_F ? evaluate_pawn_storm<Us, KingSide>(s, r, f, theirPawns) : 0);
+ pi->ksStormValue[Us] += KStormTable[relative_square(Us, s)] + bonus;
- // Queenside pawn storms
- bonus = QStormTable[relative_square(Us, s)];
- if (f <= FILE_C)
- {
- b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB);
- while (b)
- {
- // Give a bonus according to the distance of the nearest enemy pawn
- s2 = pop_1st_bit(&b);
- r2 = square_rank(s2);
- v = StormLeverBonus[f] - 4 * rank_distance(r, r2);
-
- // If enemy pawn has no pawn beside itself is particularly vulnerable.
- // Big bonus, especially against a weakness on the rook file
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- v *= (square_file(s2) == FILE_A ? 4 : 2);
-
- bonus += v;
- }
- }
- pi->qsStormValue[Us] += bonus;
+ bonus = (f <= FILE_C ? evaluate_pawn_storm<Us, QueenSide>(s, r, f, theirPawns) : 0);
+ pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus;
- // Our rank and previous one. Used for chain detection.
- b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 1));
+ // Our rank plus previous one. Used for chain detection.
+ b = rank_bb(r) | rank_bb(Us == WHITE ? r - 1 : r + 1);
// Passed, isolated, doubled or member of a pawn
// chain (but not the backward one) ?
// Test for backward pawn
//
+ backward = false;
+
// If the pawn is passed, isolated, or member of a pawn chain
// it cannot be backward. If can capture an enemy pawn or if
// there are friendly pawns behind on neighboring files it cannot
// be backward either.
- if ( (passed | isolated | chain)
- || (ourPawns & outpost_mask(opposite_color(Us), s))
- || (pos.attacks_from<PAWN>(s, Us) & theirPawns))
- backward = false;
- else
+ if ( !(passed | isolated | chain)
+ && !(ourPawns & attack_span_mask(opposite_color(Us), s))
+ && !(pos.attacks_from<PAWN>(s, Us) & theirPawns))
{
// We now know that there are no friendly pawns beside or behind this
// pawn on neighboring files. We now check whether the pawn is
backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
}
+ assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns));
+
// Test for candidate passed pawn
- candidate = !passed
- && !opposed
- && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(Us, r) | rank_bb(r)) & ourPawns)
- - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(Us, r) & theirPawns)
- >= 0);
+ candidate = !(opposed | passed)
+ && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
+ && count_1s_max_15(b) >= count_1s_max_15(attack_span_mask(Us, s) & theirPawns);
// In order to prevent doubled passed pawns from receiving a too big
// bonus, only the frontmost passed pawn on each file is considered as
if (isolated)
{
value -= IsolatedPawnPenalty[f];
- if (!(theirPawns & file_bb(f)))
+ if (!opposed)
value -= IsolatedPawnPenalty[f] / 2;
}
if (doubled)
if (backward)
{
value -= BackwardPawnPenalty[f];
- if (!(theirPawns & file_bb(f)))
+ if (!opposed)
value -= BackwardPawnPenalty[f] / 2;
}
if (chain)
}
+/// PawnInfoTable::evaluate_pawn_storm() evaluates each pawn which seems
+/// to have good chances of creating an open file by exchanging itself
+/// against an enemy pawn on an adjacent file.
+
+template<Color Us, PawnInfoTable::SideType Side>
+int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const {
+
+ const Bitboard StormFilesBB = (Side == KingSide ? FileFBB | FileGBB | FileHBB
+ : FileABB | FileBBB | FileCBB);
+ const int K = (Side == KingSide ? 2 : 4);
+ const File RookFile = (Side == KingSide ? FILE_H : FILE_A);
+
+ Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB;
+ int bonus = 0;
+
+ while (b)
+ {
+ // Give a bonus according to the distance of the nearest enemy pawn
+ Square s2 = pop_1st_bit(&b);
+ Rank r2 = square_rank(s2);
+ int v = StormLeverBonus[f] - K * rank_distance(r, r2);
+
+ // If enemy pawn has no pawn beside itself is particularly vulnerable.
+ // Big bonus, especially against a weakness on the rook file
+ if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
+ v *= (square_file(s2) == RookFile ? 4 : 2);
+
+ bonus += v;
+ }
+ return bonus;
+}
+
+
/// PawnInfo::updateShelter calculates and caches king shelter. It is called
/// only when king square changes, about 20% of total get_king_shelter() calls.
int PawnInfo::updateShelter(const Position& pos, Color c, Square ksq) {
projects / stockfish / blobdiff