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Implement calculate_reduction function

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Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Joona Kiiski 2010-01-27 22:56:11 +02:00 • committed by Marco Costalba
parent 2360c8aa2f
commit 548bae80bd
1 changed files with 15 additions and 0 deletions
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15
src/search.cpp
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@ -286,6 +286,7 @@ namespace {
bool ok_to_prune(const Position& pos, Move m, Move threat);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
Depth calculate_reduction(double baseReduction, int moveCount, Depth depth, double reductionInhibitor);
void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack& ss);
void update_gains(const Position& pos, Move move, Value before, Value after);
@ -2679,6 +2680,20 @@ namespace {
return defaultEval;
}
// calculate_reduction() returns reduction in plies based on
// moveCount and depth. Reduction is always at least one ply.
Depth calculate_reduction(double baseReduction, int moveCount, Depth depth, double reductionInhibitor) {
double red = baseReduction + ln(moveCount) * ln(depth / 2) / reductionInhibitor;
if (red >= 1.0)
return Depth(int(floor(red * int(OnePly))));
else
return Depth(0);
}
// update_history() registers a good move that produced a beta-cutoff
// in history and marks as failures all the other moves of that ply.