namespace {
+ // Struct EvalInfo contains various information computed and collected
+ // by the evaluation functions.
+ struct EvalInfo {
+
+ // Middle and end game position's static evaluations
+ Score value;
+
+ // margin[color] stores the evaluation margins we should consider for
+ // the given position. This is a kind of uncertainty estimation and
+ // typically is used by the search for pruning decisions.
+ Value margin[2];
+
+ // Pointers to material and pawn hash table entries
+ MaterialInfo* mi;
+ PawnInfo* pi;
+
+ // attackedBy[color][piece type] is a bitboard representing all squares
+ // attacked by a given color and piece type, attackedBy[color][0] contains
+ // all squares attacked by the given color.
+ Bitboard attackedBy[2][8];
+
+ // kingZone[color] is the zone around the enemy king which is considered
+ // by the king safety evaluation. This consists of the squares directly
+ // adjacent to the king, and the three (or two, for a king on an edge file)
+ // squares two ranks in front of the king. For instance, if black's king
+ // is on g8, kingZone[WHITE] is a bitboard containing the squares f8, h8,
+ // f7, g7, h7, f6, g6 and h6.
+ Bitboard kingZone[2];
+
+ // kingAttackersCount[color] is the number of pieces of the given color
+ // which attack a square in the kingZone of the enemy king.
+ int kingAttackersCount[2];
+
+ // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
+ // given color which attack a square in the kingZone of the enemy king. The
+ // weights of the individual piece types are given by the variables
+ // QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
+ // KnightAttackWeight in evaluate.cpp
+ int kingAttackersWeight[2];
+
+ // kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
+ // directly adjacent to the king of the given color. Pieces which attack
+ // more than one square are counted multiple times. For instance, if black's
+ // king is on g8 and there's a white knight on g5, this knight adds
+ // 2 to kingAdjacentZoneAttacksCount[BLACK].
+ int kingAdjacentZoneAttacksCount[2];
+ };
+
const int Sign[2] = { 1, -1 };
// Evaluation grain size, must be a power of 2
// Function prototypes
template<bool HasPopCnt>
- Value do_evaluate(const Position& pos, EvalInfo& ei);
+ Value do_evaluate(const Position& pos, Value margins[]);
template<Color Us, bool HasPopCnt>
void init_attack_tables(const Position& pos, EvalInfo& ei);
/// evaluate() is the main evaluation function. It always computes two
/// values, an endgame score and a middle game score, and interpolates
/// between them based on the remaining material.
-Value evaluate(const Position& pos, EvalInfo& ei) {
+Value evaluate(const Position& pos, Value margins[]) {
- return CpuHasPOPCNT ? do_evaluate<true>(pos, ei)
- : do_evaluate<false>(pos, ei);
+ return CpuHasPOPCNT ? do_evaluate<true>(pos, margins)
+ : do_evaluate<false>(pos, margins);
}
namespace {
template<bool HasPopCnt>
-Value do_evaluate(const Position& pos, EvalInfo& ei) {
+Value do_evaluate(const Position& pos, Value margins[]) {
+ EvalInfo ei;
ScaleFactor factor[2];
Score mobility;
factor[BLACK] = sf;
}
+ // Populate margins[]
+ margins[WHITE] = ei.margin[WHITE];
+ margins[BLACK] = ei.margin[BLACK];
+
// Interpolate between the middle game and the endgame score
return Sign[pos.side_to_move()] * scale_by_game_phase(ei.value, phase, factor);
}
// Find the attacked squares around the king which has no defenders
// apart from the king itself
- undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
- undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
- | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
- | ei.attacked_by(Us, QUEEN));
+ undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
+ undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
+ | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
+ | ei.attackedBy[Us][QUEEN]);
// Initialize the 'attackUnits' variable, which is used later on as an
// index to the KingDangerTable[] array. The initial value is based on
// Analyse enemy's safe queen contact checks. First find undefended
// squares around the king attacked by enemy queen...
- b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
+ b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces_of_color(Them);
if (b)
{
// ...then remove squares not supported by another enemy piece
- b &= ( ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
- | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK));
+ b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
+ | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
if (b)
attackUnits += QueenContactCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
}
// Analyse enemy's safe distance checks for sliders and knights
- safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
+ safe = ~(pos.pieces_of_color(Them) | ei.attackedBy[Us][0]);
b1 = pos.attacks_from<ROOK>(ksq) & safe;
b2 = pos.attacks_from<BISHOP>(ksq) & safe;
// Enemy queen safe checks
- b = (b1 | b2) & ei.attacked_by(Them, QUEEN);
+ b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
if (b)
attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
// Enemy rooks safe checks
- b = b1 & ei.attacked_by(Them, ROOK);
+ b = b1 & ei.attackedBy[Them][ROOK];
if (b)
attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b);
// Enemy bishops safe checks
- b = b2 & ei.attacked_by(Them, BISHOP);
+ b = b2 & ei.attackedBy[Them][BISHOP];
if (b)
attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b);
// Enemy knights safe checks
- b = pos.attacks_from<KNIGHT>(ksq) & ei.attacked_by(Them, KNIGHT) & safe;
+ b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
if (b)
attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b);
attackUnits = Min(99, Max(0, attackUnits));
// Finally, extract the king danger score from the KingDangerTable[]
- // array and subtract the score from evaluation. Set also ei.kingDanger[]
+ // array and subtract the score from evaluation. Set also ei.margin[]
// value that will be used for pruning because this value can sometimes
// be very big, and so capturing a single attacking piece can therefore
// result in a score change far bigger than the value of the captured piece.
ei.value -= Sign[Us] * KingDangerTable[Us][attackUnits];
- ei.kingDanger[Us] = mg_value(KingDangerTable[Us][attackUnits]);
+ ei.margin[Us] = mg_value(KingDangerTable[Us][attackUnits]);
} else
- ei.kingDanger[Us] = VALUE_ZERO;
+ ei.margin[Us] = VALUE_ZERO;
}
if (pos.square_is_empty(blockSq))
{
squaresToQueen = squares_in_front_of(Us, s);
- defendedSquares = squaresToQueen & ei.attacked_by(Us);
+ defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
// If there is an enemy rook or queen attacking the pawn from behind,
// add all X-ray attacks by the rook or queen. Otherwise consider only
&& (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<ROOK>(s)))
unsafeSquares = squaresToQueen;
else
- unsafeSquares = squaresToQueen & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
+ unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces_of_color(Them));
// If there aren't enemy attacks or pieces along the path to queen give
// huge bonus. Even bigger if we protect the pawn's path.
// pawn, or if it is undefended and attacked by an enemy piece.
Bitboard safe = SpaceMask[Us]
& ~pos.pieces(PAWN, Us)
- & ~ei.attacked_by(Them, PAWN)
- & (ei.attacked_by(Us) | ~ei.attacked_by(Them));
+ & ~ei.attackedBy[Them][PAWN]
+ & (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
// Find all squares which are at most three squares behind some friendly pawn
Bitboard behind = pos.pieces(PAWN, Us);
projects / stockfish / blobdiff