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Add comments to uncommented parts of code

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https://github.com/official-stockfish/Stockfish/pull/3250

No functional change
This commit is contained in:
Vizvezdenec
2020-12-01 15:02:35 +03:00
committed by Joost VandeVondele
parent be7a03a957
commit 8630d03dd4
2 changed files with 49 additions and 5 deletions
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src/evaluate.cpp
+16
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@@ -844,6 +844,8 @@ namespace {
behind |= shift<Down>(behind);
behind |= shift<Down+Down>(behind);
// Compute space score based on the number of safe squares and number of our pieces
// increased with number of total blocked pawns in position.
int bonus = popcount(safe) + popcount(behind & safe & ~attackedBy[Them][ALL_PIECES]);
int weight = pos.count<ALL_PIECES>(Us) - 3 + std::min(pe->blocked_count(), 9);
Score score = make_score(bonus * weight * weight / 16, 0);
@@ -905,24 +907,36 @@ namespace {
{
if (pos.opposite_bishops())
{
// For pure opposite colored bishops endgames use scale factor
// based on the number of passed pawns of the strong side.
if ( pos.non_pawn_material(WHITE) == BishopValueMg
&& pos.non_pawn_material(BLACK) == BishopValueMg)
sf = 18 + 4 * popcount(pe->passed_pawns(strongSide));
// For every other opposite colored bishops endgames use scale factor
// based on the number of all pieces of the strong side.
else
sf = 22 + 3 * pos.count<ALL_PIECES>(strongSide);
}
// For rook endgames with strong side not having overwhelming pawn number advantage
// and its pawns being on one flank and weak side protecting its pieces with a king
// use lower scale factor.
else if ( pos.non_pawn_material(WHITE) == RookValueMg
&& pos.non_pawn_material(BLACK) == RookValueMg
&& pos.count<PAWN>(strongSide) - pos.count<PAWN>(~strongSide) <= 1
&& bool(KingSide & pos.pieces(strongSide, PAWN)) != bool(QueenSide & pos.pieces(strongSide, PAWN))
&& (attacks_bb<KING>(pos.square<KING>(~strongSide)) & pos.pieces(~strongSide, PAWN)))
sf = 36;
// For queen vs no queen endgames use scale factor
// based on number of minors of side that doesn't have queen.
else if (pos.count<QUEEN>() == 1)
sf = 37 + 3 * (pos.count<QUEEN>(WHITE) == 1 ? pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK)
: pos.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE));
// In every other case use scale factor based on
// the number of pawns of the strong side reduced if pawns are on a single flank.
else
sf = std::min(sf, 36 + 7 * pos.count<PAWN>(strongSide)) - 4 * !pawnsOnBothFlanks;
// Reduce scale factor in case of pawns being on a single flank
sf -= 4 * !pawnsOnBothFlanks;
}
@@ -1046,6 +1060,8 @@ Value Eval::evaluate(const Position& pos) {
bool largePsq = psq * 16 > (NNUEThreshold1 + pos.non_pawn_material() / 64) * r50;
bool classical = largePsq || (psq > PawnValueMg / 4 && !(pos.this_thread()->nodes & 0xB));
// Use classical evaluation for really low piece endgames.
// The most critical case is a bishop + A/H file pawn vs naked king draw.
bool strongClassical = pos.non_pawn_material() < 2 * RookValueMg && pos.count<PAWN>() < 2;
v = classical || strongClassical ? Evaluation<NO_TRACE>(pos).value() : adjusted_NNUE();