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Split transposition table lookup in a separate function

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This slims down the code and is a prerequisite for
future patches.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2008-09-06 15:53:43 +02:00
parent c2c0ba875f
commit a230dc1404
3 changed files with 39 additions and 72 deletions
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50
src/search.cpp
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@@ -240,6 +240,7 @@ namespace {
bool singleReply, bool mateThreat);
bool ok_to_do_nullmove(const Position &pos);
bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
bool fail_high_ply_1();
int current_search_time();
@@ -458,7 +459,7 @@ void think(const Position &pos, bool infinite, bool ponder, int time,
// We're ready to start thinking. Call the iterative deepening loop
// function:
id_loop(pos, searchMoves);
id_loop(pos, searchMoves);;
if(UseLogFile)
LogFile.close();
@@ -859,14 +860,11 @@ namespace {
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
Value ttValue;
Depth ttDepth;
Move ttMove = MOVE_NONE;
ValueType ttValueType;
const TTEntry* tte = TT.retrieve(pos);
TT.retrieve(pos, &ttValue, &ttDepth, &ttMove, &ttValueType);
Move ttMove = (tte ? tte->move() : MOVE_NONE);
// Internal iterative deepening.
// Go with internal iterative deepening if we don't have a TT move.
if(UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly) {
search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
ttMove = ss[ply].pv[ply];
@@ -1045,24 +1043,14 @@ namespace {
return beta-1;
// Transposition table lookup
bool ttFound;
Value ttValue;
Depth ttDepth;
Move ttMove = MOVE_NONE;
ValueType ttValueType;
const TTEntry* tte = TT.retrieve(pos);
ttFound = TT.retrieve(pos, &ttValue, &ttDepth, &ttMove, &ttValueType);
if(ttFound) {
ttValue = value_from_tt(ttValue, ply);
if(ttDepth >= depth
|| ttValue >= Max(value_mate_in(100), beta)
|| ttValue < Min(value_mated_in(100), beta)) {
if((is_lower_bound(ttValueType) && ttValue >= beta) ||
(is_upper_bound(ttValueType) && ttValue < beta)) {
ss[ply].currentMove = ttMove;
return ttValue;
}
}
Move ttMove = (tte ? tte->move() : MOVE_NONE);
if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
ss[ply].currentMove = ttMove; // can be MOVE_NONE ?
return value_from_tt(tte->value(), ply);
}
Value approximateEval = quick_evaluate(pos);
@@ -1590,6 +1578,20 @@ namespace {
lock_release(&(sp->lock));
}
// ok_to_use_TT() returns true if a transposition table score
// can be used at a given point in search.
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) {
Value v = value_from_tt(tte->value(), ply);
return ( tte->depth() >= depth
|| v >= Max(value_mate_in(100), beta)
|| v < Min(value_mated_in(100), beta))
&& ( (is_lower_bound(tte->type()) && v >= beta)
|| (is_upper_bound(tte->type()) && v < beta));
}
/// The RootMove class