};
// 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 };
+ #undef S
}
//// Functions
////
-/// Constructor
+/// PawnInfoTable c'tor and d'tor instantiated one each thread
-PawnInfoTable::PawnInfoTable(unsigned numOfEntries) {
+PawnInfoTable::PawnInfoTable(unsigned numOfEntries) : size(numOfEntries) {
- size = numOfEntries;
entries = new PawnInfo[size];
if (!entries)
{
}
-/// Destructor
-
PawnInfoTable::~PawnInfoTable() {
+
delete [] entries;
}
/// PawnInfoTable::get_pawn_info() takes a position object as input, computes
-/// a PawnInfo object, and returns a pointer to it. The result is also
-/// stored in a hash table, so we don't have to recompute everything when
-/// the same pawn structure occurs again.
+/// a PawnInfo object, and returns a pointer to it. The result is also stored
+/// 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;
File f;
Rank r;
- bool passed, isolated, doubled, chain, backward, candidate;
int bonus;
+ bool passed, isolated, doubled, opposed, chain, backward, candidate;
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));
- // Passed, isolated or doubled pawn?
- passed = Position::pawn_is_passed(theirPawns, Us, s);
- isolated = Position::pawn_is_isolated(ourPawns, s);
- doubled = Position::pawn_is_doubled(ourPawns, Us, s);
+ // 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;
- // 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)
- {
- Bitboard b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB);
- while (b)
- {
- Square s2 = pop_1st_bit(&b);
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_H)
- bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 2*square_distance(s, s2);
- }
- }
- pi->ksStormValue[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;
- // Queenside pawn storms
- bonus = QStormTable[relative_square(Us, s)];
- if (f <= FILE_C)
- {
- Bitboard b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB);
- while (b)
- {
- Square s2 = pop_1st_bit(&b);
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_A)
- bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 4*square_distance(s, s2);
- }
- }
- pi->qsStormValue[Us] += bonus;
+ // Our rank plus previous one. Used for chain detection.
+ b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 1));
- // Member of a pawn chain (but not the backward one)? We could speed up
- // the test a little by introducing an array of masks indexed by color
- // and square for doing the test, but because everything is hashed,
- // it probably won't make any noticable difference.
- chain = ourPawns
- & neighboring_files_bb(f)
- & (rank_bb(r) | rank_bb(r - (Us == WHITE ? 1 : -1)));
+ // Passed, isolated, doubled or member of a pawn
+ // chain (but not the backward one) ?
+ passed = !(theirPawns & passed_pawn_mask(Us, s));
+ doubled = ourPawns & squares_behind(Us, s);
+ opposed = theirPawns & squares_in_front_of(Us, s);
+ isolated = !(ourPawns & neighboring_files_bb(f));
+ chain = ourPawns & neighboring_files_bb(f) & b;
// Test for backward pawn
//
// there are friendly pawns behind on neighboring files it cannot
// be backward either.
if ( (passed | isolated | chain)
- || (ourPawns & behind_bb(Us, r) & neighboring_files_bb(f))
+ || (ourPawns & attack_span_mask(opposite_color(Us), s))
|| (pos.attacks_from<PAWN>(s, Us) & theirPawns))
backward = false;
else
// pawn on neighboring files. We now check whether the pawn is
// backward by looking in the forward direction on the neighboring
// files, and seeing whether we meet a friendly or an enemy pawn first.
- Bitboard b = pos.attacks_from<PAWN>(s, Us);
+ b = pos.attacks_from<PAWN>(s, Us);
// Note that we are sure to find something because pawn is not passed
// nor isolated, so loop is potentially infinite, but it isn't.
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
- && !(theirPawns & file_bb(f))
- && ( 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 (passed && (ourPawns & squares_in_front_of(Us, s)))
passed = false;
- // Score this pawn
+ // Mark the pawn as passed. Pawn will be properly scored in evaluation
+ // because we need full attack info to evaluate passed pawns.
if (passed)
set_bit(&(pi->passedPawns), s);
+ // Score this pawn
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) {
- unsigned shelter = 0;
Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq);
+ unsigned shelter = 0;
unsigned r = ksq & (7 << 3);
+
for (int i = 1, k = (c ? -8 : 8); i < 4; i++)
{
r += k;