/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
+#include <algorithm>
#include <cassert>
-#include <cstring>
+#include "bitboard.h"
#include "bitcount.h"
#include "pawns.h"
#include "position.h"
-
-
-////
-//// Local definitions
-////
+#include "thread.h"
namespace {
- /// Constants and variables
-
+ #define V Value
#define S(mg, eg) make_score(mg, eg)
+ // Isolated pawn penalty by opposed flag and file
+ const Score Isolated[2][FILE_NB] = {
+ { S(37, 45), S(54, 52), S(60, 52), S(60, 52),
+ S(60, 52), S(60, 52), S(54, 52), S(37, 45) },
+ { S(25, 30), S(36, 35), S(40, 35), S(40, 35),
+ S(40, 35), S(40, 35), S(36, 35), S(25, 30) } };
+
+ // Backward pawn penalty by opposed flag
+ const Score Backward[2] = { S(67, 42), S(49, 24) };
+
+ // Unsupported pawn penalty for pawns which are neither isolated or backward,
+ // by number of pawns it supports [less than 2 / exactly 2].
+ const Score Unsupported[2] = { S(20, 10), S(25, 15) };
+
+ // Connected pawn bonus by opposed, phalanx, twice supported and rank
+ Score Connected[2][2][2][RANK_NB];
+
// Doubled pawn penalty by file
- const Score DoubledPawnPenalty[8] = {
+ const Score Doubled[FILE_NB] = {
S(13, 43), S(20, 48), S(23, 48), S(23, 48),
- S(23, 48), S(23, 48), S(20, 48), S(13, 43)
- };
-
- // Isolated pawn penalty by file
- const Score IsolatedPawnPenalty[8] = {
- S(25, 30), S(36, 35), S(40, 35), S(40, 35),
- S(40, 35), S(40, 35), S(36, 35), S(25, 30)
- };
-
- // Backward pawn penalty by file
- const Score BackwardPawnPenalty[8] = {
- S(20, 28), S(29, 31), S(33, 31), S(33, 31),
- S(33, 31), S(33, 31), S(29, 31), S(20, 28)
- };
-
- // Pawn chain membership bonus by file
- const Score ChainBonus[8] = {
- S(11,-1), S(13,-1), S(13,-1), S(14,-1),
- S(14,-1), S(13,-1), S(13,-1), S(11,-1)
- };
-
- // Candidate passed pawn bonus by rank
- const Score CandidateBonus[8] = {
- S( 0, 0), S( 6, 13), S(6,13), S(14,29),
- S(34,68), S(83,166), S(0, 0), S( 0, 0)
- };
-
- // Pawn storm tables for positions with opposite castling
- const int QStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- -22,-22,-22,-14,-6, 0, 0, 0,
- -6,-10,-10,-10,-6, 0, 0, 0,
- 4, 12, 16, 12, 4, 0, 0, 0,
- 16, 23, 23, 16, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- const int KStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0,-10,-19,-28,-33,-33,
- 0, 0, 0,-10,-15,-19,-24,-24,
- 0, 0, 0, 0, 1, 1, 1, 1,
- 0, 0, 0, 0, 1, 10, 19, 19,
- 0, 0, 0, 0, 1, 19, 31, 27,
- 0, 0, 0, 0, 0, 22, 31, 22,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- // Pawn storm open file bonuses by file
- 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 };
+ S(23, 48), S(23, 48), S(20, 48), S(13, 43) };
+
+ // Lever bonus by rank
+ const Score Lever[RANK_NB] = {
+ S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
+ S(20, 20), S(40, 40), S(0, 0), S(0, 0) };
+
+ // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
+ const Value ShelterWeakness[][RANK_NB] = {
+ { V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) },
+ { V(120), V( 0), V(28), V(76), V(88), V(103), V(104) },
+ { V(101), V( 7), V(54), V(78), V(77), V( 92), V(101) },
+ { V( 80), V(11), V(44), V(68), V(87), V( 90), V(119) } };
+
+ // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
+ const Value StormDanger[][4][RANK_NB] = {
+ { { V( 0), V( 67), V( 134), V(38), V(32) },
+ { V( 0), V( 57), V( 139), V(37), V(22) },
+ { V( 0), V( 43), V( 115), V(43), V(27) },
+ { V( 0), V( 68), V( 124), V(57), V(32) } },
+ { { V(20), V( 43), V( 100), V(56), V(20) },
+ { V(23), V( 20), V( 98), V(40), V(15) },
+ { V(23), V( 39), V( 103), V(36), V(18) },
+ { V(28), V( 19), V( 108), V(42), V(26) } },
+ { { V( 0), V( 0), V( 75), V(14), V( 2) },
+ { V( 0), V( 0), V( 150), V(30), V( 4) },
+ { V( 0), V( 0), V( 160), V(22), V( 5) },
+ { V( 0), V( 0), V( 166), V(24), V(13) } },
+ { { V( 0), V(-283), V(-281), V(57), V(31) },
+ { V( 0), V( 58), V( 141), V(39), V(18) },
+ { V( 0), V( 65), V( 142), V(48), V(32) },
+ { V( 0), V( 60), V( 126), V(51), V(19) } } };
+
+ // Max bonus for king safety. Corresponds to start position with all the pawns
+ // in front of the king and no enemy pawn on the horizon.
+ const Value MaxSafetyBonus = V(258);
#undef S
-}
+ #undef V
+
+ template<Color Us>
+ Score evaluate(const Position& pos, Pawns::Entry* e) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
+ const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
+ const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
+
+ Bitboard b, neighbours, doubled, supported, phalanx;
+ Square s;
+ bool passed, isolated, opposed, backward, lever, connected;
+ Score score = SCORE_ZERO;
+ const Square* pl = pos.squares<PAWN>(Us);
+ const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
+
+ Bitboard ourPawns = pos.pieces(Us , PAWN);
+ Bitboard theirPawns = pos.pieces(Them, PAWN);
+
+ e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
+ e->kingSquares[Us] = SQ_NONE;
+ e->semiopenFiles[Us] = 0xFF;
+ e->pawnAttacks[Us] = shift_bb<Right>(ourPawns) | shift_bb<Left>(ourPawns);
+ e->pawnsOnSquares[Us][BLACK] = popcount<Max15>(ourPawns & DarkSquares);
+ e->pawnsOnSquares[Us][WHITE] = pos.count<PAWN>(Us) - e->pawnsOnSquares[Us][BLACK];
+
+ // Loop through all pawns of the current color and score each pawn
+ while ((s = *pl++) != SQ_NONE)
+ {
+ assert(pos.piece_on(s) == make_piece(Us, PAWN));
+
+ File f = file_of(s);
+
+ e->semiopenFiles[Us] &= ~(1 << f);
+ e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
+
+ // Flag the pawn
+ neighbours = ourPawns & adjacent_files_bb(f);
+ doubled = ourPawns & forward_bb(Us, s);
+ opposed = theirPawns & forward_bb(Us, s);
+ passed = !(theirPawns & passed_pawn_mask(Us, s));
+ lever = theirPawns & pawnAttacksBB[s];
+ phalanx = neighbours & rank_bb(s);
+ supported = neighbours & rank_bb(s - Up);
+ connected = supported | phalanx;
+ isolated = !neighbours;
+
+ // Test for backward pawn.
+ // If the pawn is passed, isolated, lever or connected it cannot be
+ // backward. If there are friendly pawns behind on adjacent files
+ // or if it is sufficiently advanced, it cannot be backward either.
+ if ( (passed | isolated | lever | connected)
+ || (ourPawns & pawn_attack_span(Them, s))
+ || (relative_rank(Us, s) >= RANK_5))
+ backward = false;
+ else
+ {
+ // We now know there are no friendly pawns beside or behind this
+ // pawn on adjacent files. We now check whether the pawn is
+ // backward by looking in the forward direction on the adjacent
+ // files, and picking the closest pawn there.
+ b = pawn_attack_span(Us, s) & (ourPawns | theirPawns);
+ b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b));
+
+ // If we have an enemy pawn in the same or next rank, the pawn is
+ // backward because it cannot advance without being captured.
+ backward = (b | shift_bb<Up>(b)) & theirPawns;
+ }
+
+ assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns));
+
+ // Passed pawns will be properly scored in evaluation because we need
+ // full attack info to evaluate them. Only the frontmost passed
+ // pawn on each file is considered a true passed pawn.
+ if (passed && !doubled)
+ e->passedPawns[Us] |= s;
+
+ // Score this pawn
+ if (isolated)
+ score -= Isolated[opposed][f];
+
+ else if (backward)
+ score -= Backward[opposed];
+
+ else if (!supported)
+ score -= Unsupported[more_than_one(neighbours & rank_bb(s + Up))];
+
+ if (connected)
+ score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
+
+ if (doubled)
+ score -= Doubled[f] / distance<Rank>(s, frontmost_sq(Us, doubled));
+
+ if (lever)
+ score += Lever[relative_rank(Us, s)];
+ }
+
+ b = e->semiopenFiles[Us] ^ 0xFF;
+ e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
+
+ return score;
+ }
+} // namespace
-////
-//// Functions
-////
+namespace Pawns {
-/// PawnInfoTable c'tor and d'tor instantiated one each thread
+/// Pawns::init() initializes some tables needed by evaluation. Instead of using
+/// hard-coded tables, when makes sense, we prefer to calculate them with a formula
+/// to reduce independent parameters and to allow easier tuning and better insight.
-PawnInfoTable::PawnInfoTable(unsigned numOfEntries) : size(numOfEntries) {
+void init()
+{
+ static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 };
- entries = new PawnInfo[size];
- if (!entries)
+ for (int opposed = 0; opposed <= 1; ++opposed)
+ for (int phalanx = 0; phalanx <= 1; ++phalanx)
+ for (int apex = 0; apex <= 1; ++apex)
+ for (Rank r = RANK_2; r < RANK_8; ++r)
{
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo))
- << " bytes for pawn hash table." << std::endl;
- Application::exit_with_failure();
+ int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
+ v += (apex ? v / 2 : 0);
+ Connected[opposed][phalanx][apex][r] = make_score(3 * v / 2, v);
}
}
-PawnInfoTable::~PawnInfoTable() {
-
- delete [] entries;
-}
+/// Pawns::probe() looks up the current position's pawns configuration in
+/// the pawns hash table. It returns a pointer to the Entry if the position
+/// is found. Otherwise a new Entry is computed and stored there, so we don't
+/// have to recompute all when the same pawns configuration occurs again.
+Entry* probe(const Position& pos) {
-/// PawnInfo::clear() resets to zero the PawnInfo entry. Note that
-/// kingSquares[] is initialized to SQ_NONE instead.
+ Key key = pos.pawn_key();
+ Entry* e = pos.this_thread()->pawnsTable[key];
-void PawnInfo::clear() {
+ if (e->key == key)
+ return e;
- memset(this, 0, sizeof(PawnInfo));
- kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE;
+ e->key = key;
+ e->score = evaluate<WHITE>(pos, e) - evaluate<BLACK>(pos, e);
+ e->asymmetry = popcount<Max15>(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
+ return e;
}
-/// 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.
-
-PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
-
- assert(pos.is_ok());
-
- Key key = pos.get_pawn_key();
- unsigned index = unsigned(key & (size - 1));
- PawnInfo* pi = entries + index;
-
- // If pi->key matches the position's pawn hash key, it means that we
- // have analysed this pawn structure before, and we can simply return
- // the information we found the last time instead of recomputing it.
- if (pi->key == key)
- return pi;
+/// Entry::shelter_storm() calculates shelter and storm penalties for the file
+/// the king is on, as well as the two adjacent files.
- // Clear the PawnInfo object, and set the key
- pi->clear();
- pi->key = key;
-
- // Calculate pawn attacks
- Bitboard whitePawns = pos.pieces(PAWN, WHITE);
- Bitboard blackPawns = pos.pieces(PAWN, BLACK);
- pi->pawnAttacks[WHITE] = ((whitePawns << 9) & ~FileABB) | ((whitePawns << 7) & ~FileHBB);
- pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB);
+template<Color Us>
+Value Entry::shelter_storm(const Position& pos, Square ksq) {
- // Evaluate pawns for both colors
- pi->value = evaluate_pawns<WHITE>(pos, whitePawns, blackPawns, pi)
- - evaluate_pawns<BLACK>(pos, blackPawns, whitePawns, pi);
- return pi;
-}
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing };
-/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color
+ Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq));
+ Bitboard ourPawns = b & pos.pieces(Us);
+ Bitboard theirPawns = b & pos.pieces(Them);
+ Value safety = MaxSafetyBonus;
+ File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
-template<Color Us>
-Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, PawnInfo* pi) const {
- Bitboard b;
- Square s;
- File f;
- Rank r;
- 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);
-
- // Initialize pawn storm scores by giving bonuses for open files
- for (f = FILE_A; f <= FILE_H; f++)
- if (!(ourPawns & file_bb(f)))
- {
- pi->ksStormValue[Us] += KStormOpenFileBonus[f];
- pi->qsStormValue[Us] += QStormOpenFileBonus[f];
- pi->halfOpenFiles[Us] |= (1 << f);
- }
-
- // Loop through all pawns of the current color and score each pawn
- while ((s = *ptr++) != SQ_NONE)
+ for (File f = center - File(1); f <= center + File(1); ++f)
{
- f = square_file(s);
- r = square_rank(s);
-
- assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
-
- // 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;
-
- 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 plus previous one. Used for chain detection.
- b = 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
- //
- // 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 & attack_span_mask(opposite_color(Us), s))
- || (pos.attacks_from<PAWN>(s, Us) & theirPawns))
- backward = false;
- else
- {
- // 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 by looking in the forward direction on the neighboring
- // files, and seeing whether we meet a friendly or an enemy pawn first.
- 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.
- while (!(b & (ourPawns | theirPawns)))
- Us == WHITE ? b <<= 8 : b >>= 8;
-
- // The friendly pawn needs to be at least two ranks closer than the enemy
- // pawn in order to help the potentially backward pawn advance.
- backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
- }
-
- assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns));
-
- // Test for candidate passed pawn
- 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
- // a true passed pawn.
- if (passed && (ourPawns & squares_in_front_of(Us, s)))
- passed = false;
-
- // 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)))
- value -= IsolatedPawnPenalty[f] / 2;
- }
- if (doubled)
- value -= DoubledPawnPenalty[f];
-
- if (backward)
- {
- value -= BackwardPawnPenalty[f];
- if (!(theirPawns & file_bb(f)))
- value -= BackwardPawnPenalty[f] / 2;
- }
- if (chain)
- value += ChainBonus[f];
-
- if (candidate)
- value += CandidateBonus[relative_rank(Us, s)];
+ b = ourPawns & file_bb(f);
+ Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
+
+ b = theirPawns & file_bb(f);
+ Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
+
+ safety -= ShelterWeakness[std::min(f, FILE_H - f)][rkUs]
+ + StormDanger
+ [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing :
+ rkUs == RANK_1 ? NoFriendlyPawn :
+ rkThem == rkUs + 1 ? BlockedByPawn : Unblocked]
+ [std::min(f, FILE_H - f)][rkThem];
}
- return value;
+ return safety;
}
-/// 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.
+/// Entry::do_king_safety() calculates a bonus for king safety. It is called only
+/// when king square changes, which is about 20% of total king_safety() calls.
-template<Color Us, PawnInfoTable::SideType Side>
-int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const {
+template<Color Us>
+Score Entry::do_king_safety(const Position& pos, Square ksq) {
- 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);
+ kingSquares[Us] = ksq;
+ castlingRights[Us] = pos.can_castle(Us);
+ int minKingPawnDistance = 0;
- Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB;
- int bonus = 0;
+ Bitboard pawns = pos.pieces(Us, PAWN);
+ if (pawns)
+ while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {}
- 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 (relative_rank(Us, ksq) > RANK_4)
+ return make_score(0, -16 * minKingPawnDistance);
- // 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);
+ Value bonus = shelter_storm<Us>(pos, ksq);
- bonus += v;
- }
- return bonus;
-}
+ // If we can castle use the bonus after the castling if it is bigger
+ if (pos.can_castle(MakeCastling<Us, KING_SIDE>::right))
+ bonus = std::max(bonus, shelter_storm<Us>(pos, relative_square(Us, SQ_G1)));
+ if (pos.can_castle(MakeCastling<Us, QUEEN_SIDE>::right))
+ bonus = std::max(bonus, shelter_storm<Us>(pos, relative_square(Us, SQ_C1)));
-/// 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) {
+ return make_score(bonus, -16 * minKingPawnDistance);
+}
- Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq);
- unsigned shelter = 0;
- unsigned r = ksq & (7 << 3);
+// Explicit template instantiation
+template Score Entry::do_king_safety<WHITE>(const Position& pos, Square ksq);
+template Score Entry::do_king_safety<BLACK>(const Position& pos, Square ksq);
- for (int i = 1, k = (c ? -8 : 8); i < 4; i++)
- {
- r += k;
- shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i);
- }
- kingSquares[c] = ksq;
- kingShelters[c] = shelter;
- return shelter;
-}
+} // namespace Pawns
projects / stockfish / blobdiff