void Search::think() {
TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move());
- TBHits = TBCardinality = 0;
- RootInTB = false;
int cf = Options["Contempt"] * PawnValueEg / 100; // From centipawns
DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf);
DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(cf);
+ TBHits = 0;
+ RootInTB = false;
+ TBProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
+ TB50MoveRule = Options["Syzygy50MoveRule"];
+ TBCardinality = Options["SyzygyProbeLimit"];
+
+ // Skip TB probing when no TB found: !TBLargest -> !TBCardinality
+ if (TBCardinality > Tablebases::TBLargest)
+ {
+ TBCardinality = Tablebases::TBLargest;
+ TBProbeDepth = DEPTH_ZERO;
+ }
+
if (RootMoves.empty())
{
RootMoves.push_back(MOVE_NONE);
}
else
{
- // Check Tablebases at root
- int piecesCnt = RootPos.count<ALL_PIECES>(WHITE) + RootPos.count<ALL_PIECES>(BLACK);
- TBCardinality = Options["SyzygyProbeLimit"];
- TBProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
- if (TBCardinality > Tablebases::TBLargest)
+ if (TBCardinality >= RootPos.count<ALL_PIECES>(WHITE)
+ + RootPos.count<ALL_PIECES>(BLACK))
{
- TBCardinality = Tablebases::TBLargest;
- TBProbeDepth = 0 * ONE_PLY;
- }
- TB50MoveRule = Options["Syzygy50MoveRule"];
-
- if (piecesCnt <= TBCardinality)
- {
- TBHits = RootMoves.size();
-
// If the current root position is in the tablebases then RootMoves
// contains only moves that preserve the draw or win.
RootInTB = Tablebases::root_probe(RootPos, TBScore);
if (RootInTB)
- {
TBCardinality = 0; // Do not probe tablebases during the search
- // It might be a good idea to mangle the hash key (xor it
- // with a fixed value) in order to "clear" the hash table of
- // the results of previous probes. However, that would have to
- // be done from within the Position class, so we skip it for now.
-
- // Optional: decrease target time.
- }
else // If DTZ tables are missing, use WDL tables as a fallback
{
// Filter out moves that do not preserve a draw or win
TBCardinality = 0;
}
- if (!RootInTB)
- {
- TBHits = 0;
- }
- else if (!TB50MoveRule)
+ if (RootInTB)
{
- TBScore = TBScore > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1
- : TBScore < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
- : TBScore;
+ TBHits = RootMoves.size();
+
+ if (!TB50MoveRule)
+ TBScore = TBScore > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1
+ : TBScore < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
+ : VALUE_DRAW;
}
}
bool inCheck, givesCheck, singularExtensionNode, improving;
bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount, quietCount;
- int piecesCnt;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
}
// Step 4a. Tablebase probe
- piecesCnt = pos.count<ALL_PIECES>(WHITE) + pos.count<ALL_PIECES>(BLACK);
-
- if ( !RootNode
- && piecesCnt <= TBCardinality
- && (piecesCnt < TBCardinality || depth >= TBProbeDepth)
- && pos.rule50_count() == 0)
+ if (!RootNode && TBCardinality)
{
- int found, v = Tablebases::probe_wdl(pos, &found);
+ int piecesCnt = pos.count<ALL_PIECES>(WHITE) + pos.count<ALL_PIECES>(BLACK);
- if (found)
+ if ( piecesCnt <= TBCardinality
+ && (piecesCnt < TBCardinality || depth >= TBProbeDepth)
+ && pos.rule50_count() == 0)
{
- TBHits++;
+ int found, v = Tablebases::probe_wdl(pos, &found);
- if (TB50MoveRule) {
- value = v < -1 ? -VALUE_MATE + MAX_PLY + ss->ply
- : v > 1 ? VALUE_MATE - MAX_PLY - ss->ply
- : VALUE_DRAW + 2 * v;
- }
- else
+ if (found)
{
- value = v < 0 ? -VALUE_MATE + MAX_PLY + ss->ply
- : v > 0 ? VALUE_MATE - MAX_PLY - ss->ply
- : VALUE_DRAW;
- }
+ TBHits++;
- TT.store(posKey, value_to_tt(value, ss->ply), BOUND_EXACT,
- std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), MOVE_NONE, VALUE_NONE);
+ if (TB50MoveRule) {
+ value = v < -1 ? -VALUE_MATE + MAX_PLY + ss->ply
+ : v > 1 ? VALUE_MATE - MAX_PLY - ss->ply
+ : VALUE_DRAW + 2 * v;
+ }
+ else
+ {
+ value = v < 0 ? -VALUE_MATE + MAX_PLY + ss->ply
+ : v > 0 ? VALUE_MATE - MAX_PLY - ss->ply
+ : VALUE_DRAW;
+ }
+
+ TT.store(posKey, value_to_tt(value, ss->ply), BOUND_EXACT,
+ std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), MOVE_NONE, VALUE_NONE);
- return value;
+ return value;
+ }
}
}