/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#define S(mg, eg) make_score(mg, eg)
// Pawn penalties
- constexpr Score Backward = S( 9, 24);
- constexpr Score BlockedStorm = S(82, 82);
- constexpr Score Doubled = S(11, 56);
- constexpr Score DoubledIsolated = S(15, 57);
- constexpr Score Isolated = S( 5, 15);
- constexpr Score WeakLever = S( 0, 56);
- constexpr Score WeakUnopposed = S(13, 27);
+ constexpr Score Backward = S( 8, 25);
+ constexpr Score Doubled = S(10, 55);
+ constexpr Score Isolated = S( 3, 15);
+ constexpr Score WeakLever = S( 3, 55);
+ constexpr Score WeakUnopposed = S(13, 25);
+
+ // Bonus for blocked pawns at 5th or 6th rank
+ constexpr Score BlockedPawn[2] = { S(-13, -4), S(-5, 2) };
+
+ constexpr Score BlockedStorm[RANK_NB] = {
+ S(0, 0), S(0, 0), S(76, 78), S(-10, 15), S(-7, 10), S(-4, 6), S(-1, 2)
+ };
// Connected pawn bonus
- constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };
+ constexpr int Connected[RANK_NB] = { 0, 5, 7, 11, 24, 48, 86 };
// Strength of pawn shelter for our king by [distance from edge][rank].
// RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
#undef S
#undef V
+
+ /// evaluate() calculates a score for the static pawn structure of the given position.
+ /// We cannot use the location of pieces or king in this function, as the evaluation
+ /// of the pawn structure will be stored in a small cache for speed reasons, and will
+ /// be re-used even when the pieces have moved.
+
template<Color Us>
Score evaluate(const Position& pos, Pawns::Entry* e) {
e->passedPawns[Us] = 0;
e->kingSquares[Us] = SQ_NONE;
e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb<Us>(ourPawns);
+ e->blockedCount += popcount(shift<Up>(ourPawns) & (theirPawns | doubleAttackThem));
// Loop through all pawns of the current color and score each pawn
while ((s = *pl++) != SQ_NONE)
opposed = theirPawns & forward_file_bb(Us, s);
blocked = theirPawns & (s + Up);
stoppers = theirPawns & passed_pawn_span(Us, s);
- lever = theirPawns & PawnAttacks[Us][s];
- leverPush = theirPawns & PawnAttacks[Us][s + Up];
+ lever = theirPawns & pawn_attacks_bb(Us, s);
+ leverPush = theirPawns & pawn_attacks_bb(Us, s + Up);
doubled = ourPawns & (s - Up);
neighbours = ourPawns & adjacent_files_bb(s);
phalanx = neighbours & rank_bb(s);
support = neighbours & rank_bb(s - Up);
- e->blockedCount += blocked || more_than_one(leverPush);
-
// A pawn is backward when it is behind all pawns of the same color on
// the adjacent files and cannot safely advance.
backward = !(neighbours & forward_ranks_bb(Them, s + Up))
// Score this pawn
if (support | phalanx)
{
- int v = Connected[r] * (4 + 2 * bool(phalanx) - 2 * bool(opposed) - bool(blocked)) / 2
- + 21 * popcount(support);
+ int v = Connected[r] * (2 + bool(phalanx) - bool(opposed))
+ + 22 * popcount(support);
score += make_score(v, v * (r - 2) / 4);
}
else if (!neighbours)
{
- score -= Isolated
- + WeakUnopposed * !opposed;
-
- if ( (ourPawns & forward_file_bb(Them, s))
- && popcount(opposed) == 1
+ if ( opposed
+ && (ourPawns & forward_file_bb(Them, s))
&& !(theirPawns & adjacent_files_bb(s)))
- score -= DoubledIsolated;
+ score -= Doubled;
+ else
+ score -= Isolated
+ + WeakUnopposed * !opposed;
}
else if (backward)
- score -= Backward
- + WeakUnopposed * !opposed;
+ score -= Backward
+ + WeakUnopposed * !opposed;
if (!support)
- score -= Doubled * doubled
- + WeakLever * more_than_one(lever);
+ score -= Doubled * doubled
+ + WeakLever * more_than_one(lever);
+
+ if (blocked && r > RANK_4)
+ score += BlockedPawn[r-4];
}
return score;
namespace Pawns {
+
/// 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
/// penalty for a king, looking at the king file and the two closest files.
template<Color Us>
-Score Entry::evaluate_shelter(const Position& pos, Square ksq) {
+Score Entry::evaluate_shelter(const Position& pos, Square ksq) const {
constexpr Color Them = ~Us;
Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq);
- Bitboard ourPawns = b & pos.pieces(Us);
+ Bitboard ourPawns = b & pos.pieces(Us) & ~pawnAttacks[Them];
Bitboard theirPawns = b & pos.pieces(Them);
Score bonus = make_score(5, 5);
- File center = Utility::clamp(file_of(ksq), FILE_B, FILE_G);
+ File center = std::clamp(file_of(ksq), FILE_B, FILE_G);
for (File f = File(center - 1); f <= File(center + 1); ++f)
{
b = ourPawns & file_bb(f);
b = theirPawns & file_bb(f);
int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
- File d = File(edge_distance(f));
+ int d = edge_distance(f);
bonus += make_score(ShelterStrength[d][ourRank], 0);
if (ourRank && (ourRank == theirRank - 1))
- bonus -= BlockedStorm * int(theirRank == RANK_3);
+ bonus -= BlockedStorm[theirRank];
else
bonus -= make_score(UnblockedStorm[d][theirRank], 0);
}
Bitboard pawns = pos.pieces(Us, PAWN);
int minPawnDist = 6;
- if (pawns & PseudoAttacks[KING][ksq])
+ if (pawns & attacks_bb<KING>(ksq))
minPawnDist = 1;
else while (pawns)
minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
projects / stockfish / blobdiff