Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode);
private:
- friend void poll(SearchStack ss[], int ply);
+ friend void poll();
int ActiveThreads;
volatile bool AllThreadsShouldExit, AllThreadsShouldSleep;
const Value EasyMoveMargin = Value(0x200);
// Last seconds noise filtering (LSN)
- const bool UseLSNFiltering = true;
+ const bool UseLSNFiltering = false;
const int LSNTime = 4000; // In milliseconds
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*);
bool ok_to_do_nullmove(const Position& pos);
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);
+ bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove);
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack& ss);
int current_search_time();
int nps();
- void poll(SearchStack ss[], int ply);
+ void poll();
void ponderhit();
void wait_for_stop_or_ponderhit();
void init_ss_array(SearchStack ss[]);
tte = TT.retrieve(posKey);
ttMove = (tte ? tte->move() : MOVE_NONE);
- if (tte && ok_to_use_TT(tte, depth, beta, ply))
+ if (tte && ok_to_use_TT(tte, depth, beta, ply, allowNullmove))
{
ss[ply].currentMove = ttMove; // Can be MOVE_NONE
return value_from_tt(tte->value(), ply);
if (nullValue >= value_mate_in(PLY_MAX))
nullValue = beta;
- if (depth < 6 * OnePly)
- return nullValue;
+ // Do zugzwang verification search for high depths, don't store in TT
+ // if search was stopped.
+ if ( ( depth < 6 * OnePly
+ || search(pos, ss, beta, depth-5*OnePly, ply, false, threadID) >= beta)
+ && !AbortSearch
+ && !TM.thread_should_stop(threadID))
+ {
+ assert(value_to_tt(nullValue, ply) == nullValue);
- // Do zugzwang verification search
- Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
- if (v >= beta)
+ TT.store(posKey, nullValue, VALUE_TYPE_NS_LO, depth, MOVE_NONE);
return nullValue;
+ }
} else {
// The null move failed low, which means that we may be faced with
// some kind of threat. If the previous move was reduced, check if
tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);
- if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
+ if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply, true))
{
assert(tte->type() != VALUE_TYPE_EVAL);
alpha = bestValue;
// If we are near beta then try to get a cutoff pushing checks a bit further
- bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8;
+ bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8);
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
NodesSincePoll++;
if (NodesSincePoll >= NodesBetweenPolls)
{
- poll(ss, ply);
+ poll();
NodesSincePoll = 0;
}
}
}
- // ok_to_use_TT() returns true if a transposition table score
- // can be used at a given point in search.
+ // ok_to_use_TT() returns true if a transposition table score can be used at a
+ // given point in search. To avoid zugzwang issues TT cutoffs at the root node
+ // of a null move verification search are not allowed if the TT value was found
+ // by a null search, this is implemented testing allowNullmove and TT entry type.
- bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) {
+ bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove) {
Value v = value_from_tt(tte->value(), ply);
- return ( tte->depth() >= depth
+ return (allowNullmove || !(tte->type() & VALUE_TYPE_NULL))
+
+ && ( tte->depth() >= depth
|| v >= Max(value_mate_in(PLY_MAX), beta)
|| v < Min(value_mated_in(PLY_MAX), beta))
// looks at the time consumed so far and decides if it's time to abort the
// search.
- void poll(SearchStack ss[], int ply) {
+ void poll() {
static int lastInfoTime;
int t = current_search_time();