// If we don't already have an unusual scale factor, check for opposite
// colored bishop endgames, and use a lower scale for those.
- if ( ei.mi->game_phase() < PHASE_MIDGAME
- && pos.opposite_bishops()
- && sf == SCALE_FACTOR_NORMAL)
+ if ( ei.mi->game_phase() < PHASE_MIDGAME
+ && pos.opposite_bishops()
+ && (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN))
{
// Ignoring any pawns, do both sides only have a single bishop and no
// other pieces?
else
// Endgame with opposite-colored bishops, but also other pieces. Still
// a bit drawish, but not as drawish as with only the two bishops.
- sf = ScaleFactor(50);
+ sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
}
Value v = interpolate(score, ei.mi->game_phase(), sf);
(npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(BLACK), 2)]);
}
+ if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
+ {
+ e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
+ }
+
+ if (pos.count<PAWN>(BLACK) == 1 && npm_b - npm_w <= BishopValueMg)
+ {
+ e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN;
+ }
+
// Compute the space weight
if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)
{
};
enum ScaleFactor {
- SCALE_FACTOR_DRAW = 0,
- SCALE_FACTOR_NORMAL = 64,
- SCALE_FACTOR_MAX = 128,
- SCALE_FACTOR_NONE = 255
+ SCALE_FACTOR_DRAW = 0,
+ SCALE_FACTOR_ONEPAWN = 48,
+ SCALE_FACTOR_NORMAL = 64,
+ SCALE_FACTOR_MAX = 128,
+ SCALE_FACTOR_NONE = 255
};
enum Bound {