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Merge Joona Kiiski NULL search beta correction

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Prune more moves after a null search because of
a lower beta limit then in main search.

In test positions reduces the searched nodes of 30% !!!!

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-03-13 15:26:02 +01:00
parent 3ed603cd64
commit c8773c720a
3 changed files with 35 additions and 20 deletions
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34
src/evaluate.cpp
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@@ -289,7 +289,6 @@ namespace {
void evaluate_space(const Position &p, Color us, EvalInfo &ei);
inline Value apply_weight(Value v, int w);
Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
int count_1s_8bit(Bitboard b);
@@ -528,6 +527,22 @@ void read_weights(Color us) {
}
/// scale_by_game_phase() interpolates between a middle game and an endgame
/// score, based on game phase. It also scales the return value by a
/// ScaleFactor array.
Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
return Value(int(result) & ~(GrainSize - 1));
}
namespace {
// evaluate_common() computes terms common to all pieces attack
@@ -1144,23 +1159,6 @@ namespace {
}
// scale_by_game_phase() interpolates between a middle game and an endgame
// score, based on game phase. It also scales the return value by a
// ScaleFactor array.
Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
return Value(int(result) & ~(GrainSize - 1));
}
// count_1s_8bit() counts the number of nonzero bits in the 8 least
// significant bits of a Bitboard. This function is used by the king
// shield evaluation.