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);
}