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Only move extension based on exclusion search

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Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Joona Kiiski 2009-11-21 15:22:52 +02:00 • committed by Marco Costalba
parent 77eec9f9cb
commit 16acf57773
1 changed files with 42 additions and 0 deletions
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42
src/search.cpp
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@ -172,6 +172,9 @@ namespace {
const bool PruneDefendingMoves = false;
const bool PruneBlockingMoves = false;
// Only move margin
const Value OnlyMoveMargin = Value(100);
// Margins for futility pruning in the quiescence search, and at frontier
// and near frontier nodes.
const Value FutilityMarginQS = Value(0x80);
@ -1136,6 +1139,25 @@ namespace {
// Decide the new search depth
ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
// Only move extension
if ( moveCount == 1
&& ext < OnePly
&& depth >= 8 * OnePly
&& tte
&& (tte->type() & VALUE_TYPE_LOWER)
&& tte->move() != MOVE_NONE
&& tte->depth() >= depth - 3 * OnePly)
{
Value ttValue = value_from_tt(tte->value(), ply);
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, depth / 2, ply, false, threadID, tte->move());
if (excValue < ttValue - OnlyMoveMargin)
ext = OnePly;
}
}
newDepth = depth - OnePly + ext;
// Make and search the move
@ -1416,6 +1438,26 @@ namespace {
// Decide the new search depth
ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
// Only move extension
if ( forbiddenMove == MOVE_NONE
&& moveCount == 1
&& ext < OnePly
&& depth >= 8 * OnePly
&& tte
&& (tte->type() & VALUE_TYPE_LOWER)
&& tte->move() != MOVE_NONE
&& tte->depth() >= depth - 3 * OnePly)
{
Value ttValue = value_from_tt(tte->value(), ply);
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, depth / 2, ply, false, threadID, tte->move());
if (excValue < ttValue - OnlyMoveMargin)
ext = OnePly;
}
}
newDepth = depth - OnePly + ext;
// Futility pruning