const Score BishopPawns = S( 8, 12);
const Score RookOnPawn = S( 8, 24);
const Score TrappedRook = S(92, 0);
+ const Score CloseEnemies = S( 7, 0);
const Score SafeCheck = S(20, 20);
const Score OtherCheck = S(10, 10);
const Score ThreatByHangingPawn = S(71, 61);
// evaluate_king() assigns bonuses and penalties to a king of a given color
+ const Bitboard WhiteCamp = Rank1BB | Rank2BB | Rank3BB | Rank4BB | Rank5BB;
+ const Bitboard BlackCamp = Rank8BB | Rank7BB | Rank6BB | Rank5BB | Rank4BB;
+ const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
+ const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+ const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
+
+ const Bitboard KingFlank[COLOR_NB][FILE_NB] = {
+ { QueenSide & WhiteCamp, QueenSide & WhiteCamp, QueenSide & WhiteCamp, CenterFiles & WhiteCamp,
+ CenterFiles & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp },
+ { QueenSide & BlackCamp, QueenSide & BlackCamp, QueenSide & BlackCamp, CenterFiles & BlackCamp,
+ CenterFiles & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp },
+ };
+
template<Color Us, bool DoTrace>
Score evaluate_king(const Position& pos, const EvalInfo& ei) {
score -= KingDanger[std::max(std::min(attackUnits, 399), 0)];
}
+ // King tropism: firstly, find squares that opponent attacks in our king flank
+ b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[Us][file_of(ksq)];
+
+ assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
+ assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
+
+ // Secondly, add the squares which are attacked twice in that flank and
+ // which are not defended by our pawns.
+ b = (Us == WHITE ? b << 4 : b >> 4)
+ | (b & ei.attackedBy2[Them] & ~ei.attackedBy[Us][PAWN]);
+
+ score -= CloseEnemies * popcount(b);
+
if (DoTrace)
Trace::add(KING, Us, score);
// evaluate_threats() assigns bonuses according to the types of the attacking
// and the attacked pieces.
- const Bitboard WhiteCamp = Rank1BB | Rank2BB | Rank3BB | Rank4BB | Rank5BB;
- const Bitboard BlackCamp = Rank8BB | Rank7BB | Rank6BB | Rank5BB | Rank4BB;
- const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
- const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
- const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
-
- const Bitboard KingFlank[COLOR_NB][FILE_NB] = {
- { QueenSide & WhiteCamp, QueenSide & WhiteCamp, QueenSide & WhiteCamp, CenterFiles & WhiteCamp,
- CenterFiles & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp },
- { QueenSide & BlackCamp, QueenSide & BlackCamp, QueenSide & BlackCamp, CenterFiles & BlackCamp,
- CenterFiles & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp },
- };
-
template<Color Us, bool DoTrace>
Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
score += ThreatByPawnPush * popcount(b);
- // King tropism: firstly, find squares that we attack in the enemy king flank
- b = ei.attackedBy[Us][ALL_PIECES] & KingFlank[Them][file_of(pos.square<KING>(Them))];
-
- // Secondly, add to the bitboard the squares which we attack twice in that flank
- // but which are not protected by a enemy pawn. Note the trick to shift away the
- // previous attack bits to the empty part of the bitboard.
- b = (b & ei.attackedBy2[Us] & ~ei.attackedBy[Them][PAWN])
- | (Us == WHITE ? b >> 4 : b << 4);
-
- // Count all these squares with a single popcount
- score += make_score(7 * popcount(b), 0);
-
if (DoTrace)
Trace::add(THREAT, Us, score);