#include "tt.h"
#include "uci.h"
+#ifdef SYZYGY
+#include "syzygy/tbprobe.h"
+#endif
+
namespace Search {
volatile SignalsType Signals;
Position RootPos;
Time::point SearchTime;
StateStackPtr SetupStates;
+ int TBCardinality;
+ uint64_t TBHits;
+ bool RootInTB;
+ bool TB50MoveRule;
+ Depth TBProbeDepth;
+ Value TBScore;
}
using std::string;
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);
}
else
{
+#ifdef SYZYGY
+ // Check Tablebases at root
+ int piecesCnt = RootPos.total_piece_count();
+ TBCardinality = Options["SyzygyProbeLimit"];
+ TBProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
+ if (TBCardinality > Tablebases::TBLargest)
+ {
+ 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
+ RootInTB = Tablebases::root_probe_wdl(RootPos, TBScore);
+
+ // Only probe during search if winning
+ if (TBScore <= VALUE_DRAW)
+ TBCardinality = 0;
+ }
+
+ if (!RootInTB)
+ {
+ TBHits = 0;
+ }
+ else if (!TB50MoveRule)
+ {
+ TBScore = TBScore > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1
+ : TBScore < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
+ : TBScore;
+ }
+ }
+#endif
+
for (size_t i = 0; i < Threads.size(); ++i)
Threads[i]->maxPly = 0;
return ttValue;
}
+#ifdef SYZYGY
+ // Step 4a. Tablebase probe
+ if ( !RootNode
+ && pos.total_piece_count() <= TBCardinality
+ && ( pos.total_piece_count() < TBCardinality || depth >= TBProbeDepth )
+ && pos.rule50_count() == 0)
+ {
+ int found, v = Tablebases::probe_wdl(pos, &found);
+
+ if (found)
+ {
+ TBHits++;
+
+ 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;
+ }
+ }
+#endif
+
// Step 5. Evaluate the position statically and update parent's gain statistics
if (inCheck)
{
Depth d = updated ? depth : depth - ONE_PLY;
Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore;
+ bool tb = RootInTB;
+ if (tb)
+ {
+ if (abs(v) >= VALUE_MATE - MAX_PLY)
+ tb = false;
+ else
+ v = TBScore;
+ }
+
if (ss.rdbuf()->in_avail()) // Not at first line
ss << "\n";
ss << "info depth " << d / ONE_PLY
<< " seldepth " << selDepth
<< " multipv " << i + 1
- << " score " << (i == PVIdx ? UCI::format_value(v, alpha, beta) : UCI::format_value(v))
+ << " score " << ((!tb && i == PVIdx) ? UCI::format_value(v, alpha, beta) : UCI::format_value(v))
<< " nodes " << pos.nodes_searched()
<< " nps " << pos.nodes_searched() * 1000 / elapsed
+ << " tbhits " << TBHits
<< " time " << elapsed
<< " pv";