/// Types
- // IterationInfoType stores search results for each iteration
- //
- // Because we use relatively small (dynamic) aspiration window,
- // there happens many fail highs and fail lows in root. And
- // because we don't do researches in those cases, "value" stored
- // here is not necessarily exact. Instead in case of fail high/low
- // we guess what the right value might be and store our guess
- // as a "speculated value" and then move on. Speculated values are
- // used just to calculate aspiration window width, so also if are
- // not exact is not big a problem.
-
- struct IterationInfoType {
-
- IterationInfoType(Value v = Value(0), Value sv = Value(0))
- : value(v), speculatedValue(sv) {}
-
- Value value, speculatedValue;
- };
+ // ThreadsManager class is used to handle all the threads related stuff in search,
+ // init, starting, parking and, the most important, launching a slave thread at a
+ // split point are what this class does. All the access to shared thread data is
+ // done through this class, so that we avoid using global variables instead.
+
+ class ThreadsManager {
+ /* As long as the single ThreadsManager object is defined as a global we don't
+ need to explicitly initialize to zero its data members because variables with
+ static storage duration are automatically set to zero before enter main()
+ */
+ public:
+ void init_threads();
+ void exit_threads();
+
+ int active_threads() const { return ActiveThreads; }
+ void set_active_threads(int newActiveThreads) { ActiveThreads = newActiveThreads; }
+ void incrementNodeCounter(int threadID) { threads[threadID].nodes++; }
+ void incrementBetaCounter(Color us, Depth d, int threadID) { threads[threadID].betaCutOffs[us] += unsigned(d); }
+
+ void resetNodeCounters();
+ void resetBetaCounters();
+ int64_t nodes_searched() const;
+ void get_beta_counters(Color us, int64_t& our, int64_t& their) const;
+ bool available_thread_exists(int master) const;
+ bool thread_is_available(int slave, int master) const;
+ bool thread_should_stop(int threadID) const;
+ void wake_sleeping_threads();
+ void put_threads_to_sleep();
+ void idle_loop(int threadID, SplitPoint* waitSp);
+ bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode);
+
+ private:
+ friend void poll(SearchStack ss[], int ply);
+
+ int ActiveThreads;
+ volatile bool AllThreadsShouldExit, AllThreadsShouldSleep;
+ Thread threads[MAX_THREADS];
+ SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX];
- // The BetaCounterType class is used to order moves at ply one.
- // Apart for the first one that has its score, following moves
- // normally have score -VALUE_INFINITE, so are ordered according
- // to the number of beta cutoffs occurred under their subtree during
- // the last iteration. The counters are per thread variables to avoid
- // concurrent accessing under SMP case.
+ Lock MPLock, WaitLock;
- struct BetaCounterType {
+#if !defined(_MSC_VER)
+ pthread_cond_t WaitCond;
+#else
+ HANDLE SitIdleEvent[MAX_THREADS];
+#endif
- BetaCounterType();
- void clear();
- void add(Color us, Depth d, int threadID);
- void read(Color us, int64_t& our, int64_t& their);
};
- // The RootMove class is used for moves at the root at the tree. For each
+ // RootMove struct is used for moves at the root at the tree. For each
// root move, we store a score, a node count, and a PV (really a refutation
// in the case of moves which fail low).
};
- /// Constants
-
- // Search depth at iteration 1
- const Depth InitialDepth = OnePly;
-
- // Depth limit for selective search
- const Depth SelectiveDepth = 7 * OnePly;
-
- // Use internal iterative deepening?
- const bool UseIIDAtPVNodes = true;
- const bool UseIIDAtNonPVNodes = true;
+ /// Adjustments
- // Internal iterative deepening margin. At Non-PV moves, when
- // UseIIDAtNonPVNodes is true, we do an internal iterative deepening
- // search when the static evaluation is at most IIDMargin below beta.
- const Value IIDMargin = Value(0x100);
+ // Step 6. Razoring
- // Easy move margin. An easy move candidate must be at least this much
- // better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
+ // Maximum depth for razoring
+ const Depth RazorDepth = 4 * OnePly;
- // Problem margin. If the score of the first move at iteration N+1 has
- // dropped by more than this since iteration N, the boolean variable
- // "Problem" is set to true, which will make the program spend some extra
- // time looking for a better move.
- const Value ProblemMargin = Value(0x28);
+ // Dynamic razoring margin based on depth
+ inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); }
- // No problem margin. If the boolean "Problem" is true, and a new move
- // is found at the root which is less than NoProblemMargin worse than the
- // best move from the previous iteration, Problem is set back to false.
- const Value NoProblemMargin = Value(0x14);
+ // Step 8. Null move search with verification search
// Null move margin. A null move search will not be done if the static
// evaluation of the position is more than NullMoveMargin below beta.
const Value NullMoveMargin = Value(0x200);
- // If the TT move is at least SingleReplyMargin better then the
+ // Maximum depth for use of dynamic threat detection when null move fails low
+ const Depth ThreatDepth = 5 * OnePly;
+
+ // Step 9. Internal iterative deepening
+
+ // Minimum depth for use of internal iterative deepening
+ const Depth IIDDepthAtPVNodes = 5 * OnePly;
+ const Depth IIDDepthAtNonPVNodes = 8 * OnePly;
+
+ // At Non-PV nodes we do an internal iterative deepening search
+ // when the static evaluation is at most IIDMargin below beta.
+ const Value IIDMargin = Value(0x100);
+
+ // Step 11. Decide the new search depth
+
+ // Extensions. Configurable UCI options
+ // Array index 0 is used at non-PV nodes, index 1 at PV nodes.
+ Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
+ Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
+
+ // Minimum depth for use of singular extension
+ const Depth SingularExtensionDepthAtPVNodes = 6 * OnePly;
+ const Depth SingularExtensionDepthAtNonPVNodes = 8 * OnePly;
+
+ // If the TT move is at least SingularExtensionMargin better then the
// remaining ones we will extend it.
- const Value SingleReplyMargin = Value(0x20);
+ const Value SingularExtensionMargin = Value(0x20);
+
+ // Step 12. Futility pruning
- // Margins for futility pruning in the quiescence search, and at frontier
- // and near frontier nodes.
+ // Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
- // Each move futility margin is decreased
- const Value IncrementalFutilityMargin = Value(0x8);
+ // Futility lookup tables (initialized at startup) and their getter functions
+ int32_t FutilityMarginsMatrix[16][64]; // [depth][moveNumber]
+ int FutilityMoveCountArray[32]; // [depth]
- // Depth limit for razoring
- const Depth RazorDepth = 4 * OnePly;
+ inline Value futility_margin(Depth d, int mn) { return Value(d < 7 * OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); }
+ inline int futility_move_count(Depth d) { return d < 16 * OnePly ? FutilityMoveCountArray[d] : 512; }
+
+ // Step 14. Reduced search
- /// Variables initialized by UCI options
+ // Reduction lookup tables (initialized at startup) and their getter functions
+ int8_t PVReductionMatrix[64][64]; // [depth][moveNumber]
+ int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber]
- // Depth limit for use of dynamic threat detection
- Depth ThreatDepth;
+ inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
+ inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
+
+ // Common adjustments
+
+ // Search depth at iteration 1
+ const Depth InitialDepth = OnePly;
+
+ // Easy move margin. An easy move candidate must be at least this much
+ // better than the second best move.
+ const Value EasyMoveMargin = Value(0x200);
// Last seconds noise filtering (LSN)
const bool UseLSNFiltering = true;
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
- // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
- Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
- Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
- // Iteration counters
+ /// Global variables
+
+ // Iteration counter
int Iteration;
- BetaCounterType BetaCounter;
// Scores and number of times the best move changed for each iteration
- IterationInfoType IterationInfo[PLY_MAX_PLUS_2];
+ Value ValueByIteration[PLY_MAX_PLUS_2];
int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
// Search window management
int MultiPV;
// Time managment variables
- int RootMoveNumber;
- int SearchStartTime;
- int MaxNodes, MaxDepth;
- int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
+ int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime;
+ int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
- bool AbortSearch, Quit;
- bool FailHigh, FailLow, Problem;
+ bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
// Show current line?
bool ShowCurrentLine;
bool UseLogFile;
std::ofstream LogFile;
- // Natural logarithmic lookup table and its getter function
- double lnArray[512];
- inline double ln(int i) { return lnArray[i]; }
-
- // MP related variables
- int ActiveThreads = 1;
+ // Multi-threads related variables
Depth MinimumSplitDepth;
int MaxThreadsPerSplitPoint;
- Thread Threads[THREAD_MAX];
- Lock MPLock;
- Lock IOLock;
- bool AllThreadsShouldExit = false;
- SplitPoint SplitPointStack[THREAD_MAX][ACTIVE_SPLIT_POINTS_MAX];
- bool Idle = true;
-
-#if !defined(_MSC_VER)
- pthread_cond_t WaitCond;
- pthread_mutex_t WaitLock;
-#else
- HANDLE SitIdleEvent[THREAD_MAX];
-#endif
+ ThreadsManager TM;
- // Node counters, used only by thread[0] but try to keep in different
- // cache lines (64 bytes each) from the heavy SMP read accessed variables.
+ // Node counters, used only by thread[0] but try to keep in different cache
+ // lines (64 bytes each) from the heavy multi-thread read accessed variables.
int NodesSincePoll;
int NodesBetweenPolls = 30000;
// History table
History H;
- /// Functions
+ /// Local functions
Value id_loop(const Position& pos, Move searchMoves[]);
- Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta);
+ Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
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);
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
- Depth calculate_reduction(double baseReduction, int moveCount, Depth depth, double reductionInhibitor);
void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack& ss);
void update_gains(const Position& pos, Move move, Value before, Value after);
- bool fail_high_ply_1();
int current_search_time();
int nps();
- void poll();
+ void poll(SearchStack ss[], int ply);
void ponderhit();
- void print_current_line(SearchStack ss[], int ply, int threadID);
void wait_for_stop_or_ponderhit();
void init_ss_array(SearchStack ss[]);
-
- void idle_loop(int threadID, SplitPoint* waitSp);
- void init_split_point_stack();
- void destroy_split_point_stack();
- bool thread_should_stop(int threadID);
- bool thread_is_available(int slave, int master);
- bool idle_thread_exists(int master);
- bool split(const Position& pos, SearchStack* ss, int ply,
- Value *alpha, Value *beta, Value *bestValue,
- const Value futilityValue, Depth depth, int *moves,
- MovePicker *mp, int master, bool pvNode);
- void wake_sleeping_threads();
+ void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value);
#if !defined(_MSC_VER)
void *init_thread(void *threadID);
//// Functions
////
+/// init_threads(), exit_threads() and nodes_searched() are helpers to
+/// give accessibility to some TM methods from outside of current file.
+
+void init_threads() { TM.init_threads(); }
+void exit_threads() { TM.exit_threads(); }
+int64_t nodes_searched() { return TM.nodes_searched(); }
+
/// perft() is our utility to verify move generation is bug free. All the legal
/// moves up to given depth are generated and counted and the sum returned.
int perft(Position& pos, Depth depth)
{
+ StateInfo st;
Move move;
int sum = 0;
- MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
+ MovePicker mp(pos, MOVE_NONE, depth, H);
// If we are at the last ply we don't need to do and undo
// the moves, just to count them.
CheckInfo ci(pos);
while ((move = mp.get_next_move()) != MOVE_NONE)
{
- StateInfo st;
pos.do_move(move, st, ci, pos.move_is_check(move, ci));
sum += perft(pos, depth - OnePly);
pos.undo_move(move);
int maxNodes, int maxTime, Move searchMoves[]) {
// Initialize global search variables
- Idle = StopOnPonderhit = AbortSearch = Quit = false;
- FailHigh = FailLow = Problem = false;
+ StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false;
+ MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0;
NodesSincePoll = 0;
+ TM.resetNodeCounters();
SearchStartTime = get_system_time();
ExactMaxTime = maxTime;
MaxDepth = maxDepth;
UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch;
// Look for a book move, only during games, not tests
- if (UseTimeManagement && !ponder && get_option_value_bool("OwnBook"))
+ if (UseTimeManagement && get_option_value_bool("OwnBook"))
{
- Move bookMove;
if (get_option_value_string("Book File") != OpeningBook.file_name())
OpeningBook.open(get_option_value_string("Book File"));
- bookMove = OpeningBook.get_move(pos);
+ Move bookMove = OpeningBook.get_move(pos);
if (bookMove != MOVE_NONE)
{
+ if (PonderSearch)
+ wait_for_stop_or_ponderhit();
+
cout << "bestmove " << bookMove << endl;
return true;
}
}
- for (int i = 0; i < THREAD_MAX; i++)
- {
- Threads[i].nodes = 0ULL;
- Threads[i].failHighPly1 = false;
- }
-
+ // Reset loseOnTime flag at the beginning of a new game
if (button_was_pressed("New Game"))
- loseOnTime = false; // Reset at the beginning of a new game
+ loseOnTime = false;
// Read UCI option values
TT.set_size(get_option_value_int("Hash"));
if (button_was_pressed("Clear Hash"))
TT.clear();
- bool PonderingEnabled = get_option_value_bool("Ponder");
- MultiPV = get_option_value_int("MultiPV");
-
- CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
- CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
-
+ CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
+ CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
SingleEvasionExtension[1] = Depth(get_option_value_int("Single Evasion Extension (PV nodes)"));
SingleEvasionExtension[0] = Depth(get_option_value_int("Single Evasion Extension (non-PV nodes)"));
-
PawnPushTo7thExtension[1] = Depth(get_option_value_int("Pawn Push to 7th Extension (PV nodes)"));
PawnPushTo7thExtension[0] = Depth(get_option_value_int("Pawn Push to 7th Extension (non-PV nodes)"));
+ PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)"));
+ PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)"));
+ PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)"));
+ PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)"));
+ MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
+ MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
+
+ MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
+ MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
+ ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
+ MultiPV = get_option_value_int("MultiPV");
+ Chess960 = get_option_value_bool("UCI_Chess960");
+ UseLogFile = get_option_value_bool("Use Search Log");
- PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)"));
- PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)"));
-
- PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)"));
- PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)"));
-
- MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
- MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
-
- ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
-
- Chess960 = get_option_value_bool("UCI_Chess960");
- ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
- UseLogFile = get_option_value_bool("Use Search Log");
if (UseLogFile)
LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
- MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
- MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
-
read_weights(pos.side_to_move());
// Set the number of active threads
int newActiveThreads = get_option_value_int("Threads");
- if (newActiveThreads != ActiveThreads)
+ if (newActiveThreads != TM.active_threads())
{
- ActiveThreads = newActiveThreads;
- init_eval(ActiveThreads);
+ TM.set_active_threads(newActiveThreads);
+ init_eval(TM.active_threads());
// HACK: init_eval() destroys the static castleRightsMask[] array in the
// Position class. The below line repairs the damage.
Position p(pos.to_fen());
}
// Wake up sleeping threads
- wake_sleeping_threads();
-
- for (int i = 1; i < ActiveThreads; i++)
- assert(thread_is_available(i, 0));
+ TM.wake_sleeping_threads();
// Set thinking time
int myTime = time[side_to_move];
}
}
- if (PonderingEnabled)
+ if (get_option_value_bool("Ponder"))
{
MaxSearchTime += MaxSearchTime / 4;
MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
}
}
- // Set best NodesBetweenPolls interval
+ // Set best NodesBetweenPolls interval to avoid lagging under
+ // heavy time pressure.
if (MaxNodes)
NodesBetweenPolls = Min(MaxNodes, 30000);
else if (myTime && myTime < 1000)
else
NodesBetweenPolls = 30000;
- // Write information to search log file
+ // Write search information to log file
if (UseLogFile)
LogFile << "Searching: " << pos.to_fen() << endl
<< "infinite: " << infinite
<< " increment: " << myIncrement
<< " moves to go: " << movesToGo << endl;
- // LSN filtering. Used only for developing purpose. Disabled by default.
+ // LSN filtering. Used only for developing purposes, disabled by default
if ( UseLSNFiltering
&& loseOnTime)
{
// We're ready to start thinking. Call the iterative deepening loop function
Value v = id_loop(pos, searchMoves);
-
if (UseLSNFiltering)
{
// Step 1. If this is sudden death game and our position is hopeless,
if (UseLogFile)
LogFile.close();
- Idle = true;
+ TM.put_threads_to_sleep();
+
return !Quit;
}
-/// init_threads() is called during startup. It launches all helper threads,
-/// and initializes the split point stack and the global locks and condition
-/// objects.
-
-void init_threads() {
-
- volatile int i;
- bool ok;
-
-#if !defined(_MSC_VER)
- pthread_t pthread[1];
-#endif
-
- // Init our logarithmic lookup table
- for (i = 0; i < 512; i++)
- lnArray[i] = log(double(i)); // log() returns base-e logarithm
-
- for (i = 0; i < THREAD_MAX; i++)
- Threads[i].activeSplitPoints = 0;
-
- // Initialize global locks
- lock_init(&MPLock, NULL);
- lock_init(&IOLock, NULL);
-
- init_split_point_stack();
-
-#if !defined(_MSC_VER)
- pthread_mutex_init(&WaitLock, NULL);
- pthread_cond_init(&WaitCond, NULL);
-#else
- for (i = 0; i < THREAD_MAX; i++)
- SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
-#endif
-
- // All threads except the main thread should be initialized to idle state
- for (i = 1; i < THREAD_MAX; i++)
- {
- Threads[i].stop = false;
- Threads[i].workIsWaiting = false;
- Threads[i].idle = true;
- Threads[i].running = false;
- }
+/// init_search() is called during startup. It initializes various lookup tables
- // Launch the helper threads
- for (i = 1; i < THREAD_MAX; i++)
- {
-#if !defined(_MSC_VER)
- ok = (pthread_create(pthread, NULL, init_thread, (void*)(&i)) == 0);
-#else
- DWORD iID[1];
- ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID) != NULL);
-#endif
+void init_search() {
- if (!ok)
+ // Init our reduction lookup tables
+ for (int i = 1; i < 64; i++) // i == depth (OnePly = 1)
+ for (int j = 1; j < 64; j++) // j == moveNumber
{
- cout << "Failed to create thread number " << i << endl;
- Application::exit_with_failure();
+ double pvRed = 0.5 + log(double(i)) * log(double(j)) / 6.0;
+ double nonPVRed = 0.5 + log(double(i)) * log(double(j)) / 3.0;
+ PVReductionMatrix[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0);
+ NonPVReductionMatrix[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
}
- // Wait until the thread has finished launching
- while (!Threads[i].running);
- }
-}
-
-
-/// stop_threads() is called when the program exits. It makes all the
-/// helper threads exit cleanly.
-
-void stop_threads() {
-
- ActiveThreads = THREAD_MAX; // HACK
- Idle = false; // HACK
- wake_sleeping_threads();
- AllThreadsShouldExit = true;
- for (int i = 1; i < THREAD_MAX; i++)
- {
- Threads[i].stop = true;
- while (Threads[i].running);
- }
- destroy_split_point_stack();
-}
-
-
-/// nodes_searched() returns the total number of nodes searched so far in
-/// the current search.
-
-int64_t nodes_searched() {
+ // Init futility margins array
+ for (int i = 0; i < 16; i++) // i == depth (OnePly = 2)
+ for (int j = 0; j < 64; j++) // j == moveNumber
+ {
+ // FIXME: test using log instead of BSR
+ FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j;
+ }
- int64_t result = 0ULL;
- for (int i = 0; i < ActiveThreads; i++)
- result += Threads[i].nodes;
- return result;
+ // Init futility move count array
+ for (int i = 0; i < 32; i++) // i == depth (OnePly = 2)
+ FutilityMoveCountArray[i] = 3 + (1 << (3 * i / 8));
}
currentMove = threatMove = MOVE_NONE;
reduction = Depth(0);
eval = VALUE_NONE;
- evalInfo = NULL;
}
void SearchStack::initKillers() {
Position p(pos);
SearchStack ss[PLY_MAX_PLUS_2];
+ Move EasyMove = MOVE_NONE;
+ Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
- // searchMoves are verified, copied, scored and sorted
+ // Moves to search are verified, copied, scored and sorted
RootMoveList rml(p, searchMoves);
+ // Handle special case of searching on a mate/stale position
if (rml.move_count() == 0)
{
if (PonderSearch)
wait_for_stop_or_ponderhit();
- return pos.is_check()? -VALUE_MATE : VALUE_DRAW;
+ return pos.is_check() ? -VALUE_MATE : VALUE_DRAW;
}
- // Print RootMoveList c'tor startup scoring to the standard output,
- // so that we print information also for iteration 1.
- cout << "info depth " << 1 << "\ninfo depth " << 1
+ // Print RootMoveList startup scoring to the standard output,
+ // so to output information also for iteration 1.
+ cout << "info depth " << 1
+ << "\ninfo depth " << 1
<< " score " << value_to_string(rml.get_move_score(0))
<< " time " << current_search_time()
- << " nodes " << nodes_searched()
+ << " nodes " << TM.nodes_searched()
<< " nps " << nps()
<< " pv " << rml.get_move(0) << "\n";
TT.new_search();
H.clear();
init_ss_array(ss);
- IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0));
+ ValueByIteration[1] = rml.get_move_score(0);
Iteration = 1;
// Is one move significantly better than others after initial scoring ?
- Move EasyMove = MOVE_NONE;
if ( rml.move_count() == 1
|| rml.get_move_score(0) > rml.get_move_score(1) + EasyMoveMargin)
EasyMove = rml.get_move(0);
while (Iteration < PLY_MAX)
{
// Initialize iteration
- rml.sort();
Iteration++;
BestMoveChangesByIteration[Iteration] = 0;
- if (Iteration <= 5)
- ExtraSearchTime = 0;
cout << "info depth " << Iteration << endl;
- // Calculate dynamic search window based on previous iterations
- Value alpha, beta;
-
- if (MultiPV == 1 && Iteration >= 6 && abs(IterationInfo[Iteration - 1].value) < VALUE_KNOWN_WIN)
+ // Calculate dynamic aspiration window based on previous iterations
+ if (MultiPV == 1 && Iteration >= 6 && abs(ValueByIteration[Iteration - 1]) < VALUE_KNOWN_WIN)
{
- int prevDelta1 = IterationInfo[Iteration - 1].speculatedValue - IterationInfo[Iteration - 2].speculatedValue;
- int prevDelta2 = IterationInfo[Iteration - 2].speculatedValue - IterationInfo[Iteration - 3].speculatedValue;
+ int prevDelta1 = ValueByIteration[Iteration - 1] - ValueByIteration[Iteration - 2];
+ int prevDelta2 = ValueByIteration[Iteration - 2] - ValueByIteration[Iteration - 3];
- int delta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16);
+ AspirationDelta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16);
+ AspirationDelta = (AspirationDelta + 7) / 8 * 8; // Round to match grainSize
- delta = (delta + 7) / 8 * 8; // Round to match grainSize
- AspirationDelta = delta;
-
- alpha = Max(IterationInfo[Iteration - 1].value - delta, -VALUE_INFINITE);
- beta = Min(IterationInfo[Iteration - 1].value + delta, VALUE_INFINITE);
- }
- else
- {
- alpha = - VALUE_INFINITE;
- beta = VALUE_INFINITE;
+ alpha = Max(ValueByIteration[Iteration - 1] - AspirationDelta, -VALUE_INFINITE);
+ beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, VALUE_INFINITE);
}
- // Search to the current depth
- Value value = root_search(p, ss, rml, alpha, beta);
+ // Search to the current depth, rml is updated and sorted, alpha and beta could change
+ value = root_search(p, ss, rml, &alpha, &beta);
// Write PV to transposition table, in case the relevant entries have
// been overwritten during the search.
break; // Value cannot be trusted. Break out immediately!
//Save info about search result
- Value speculatedValue;
- bool fHigh = false;
- bool fLow = false;
- Value delta = value - IterationInfo[Iteration - 1].value;
+ ValueByIteration[Iteration] = value;
- if (value >= beta)
- {
- assert(delta > 0);
-
- fHigh = true;
- speculatedValue = value + delta;
- BestMoveChangesByIteration[Iteration] += 2; // Allocate more time
- }
- else if (value <= alpha)
- {
- assert(value == alpha);
- assert(delta < 0);
-
- fLow = true;
- speculatedValue = value + delta;
- BestMoveChangesByIteration[Iteration] += 3; // Allocate more time
- } else
- speculatedValue = value;
-
- speculatedValue = Min(Max(speculatedValue, -VALUE_INFINITE), VALUE_INFINITE);
- IterationInfo[Iteration] = IterationInfoType(value, speculatedValue);
-
- // Drop the easy move if it differs from the new best move
+ // Drop the easy move if differs from the new best move
if (ss[0].pv[0] != EasyMove)
EasyMove = MOVE_NONE;
- Problem = false;
-
if (UseTimeManagement)
{
// Time to stop?
// Stop search early when the last two iterations returned a mate score
if ( Iteration >= 6
- && abs(IterationInfo[Iteration].value) >= abs(VALUE_MATE) - 100
- && abs(IterationInfo[Iteration-1].value) >= abs(VALUE_MATE) - 100)
+ && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100
+ && abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100)
stopSearch = true;
- // Stop search early if one move seems to be much better than the rest
- int64_t nodes = nodes_searched();
+ // Stop search early if one move seems to be much better than the others
+ int64_t nodes = TM.nodes_searched();
if ( Iteration >= 8
- && !fLow
- && !fHigh
&& EasyMove == ss[0].pv[0]
&& ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100
&& current_search_time() > MaxSearchTime / 16)
if (stopSearch)
{
- if (!PonderSearch)
- break;
- else
+ if (PonderSearch)
StopOnPonderhit = true;
+ else
+ break;
}
}
break;
}
- rml.sort();
-
// If we are pondering or in infinite search, we shouldn't print the
// best move before we are told to do so.
if (!AbortSearch && (PonderSearch || InfiniteSearch))
wait_for_stop_or_ponderhit();
else
// Print final search statistics
- cout << "info nodes " << nodes_searched()
+ cout << "info nodes " << TM.nodes_searched()
<< " nps " << nps()
<< " time " << current_search_time()
<< " hashfull " << TT.full() << endl;
ss[0].pv[0] = rml.get_move(0);
ss[0].pv[1] = MOVE_NONE;
}
+
+ assert(ss[0].pv[0] != MOVE_NONE);
+
cout << "bestmove " << ss[0].pv[0];
+
if (ss[0].pv[1] != MOVE_NONE)
cout << " ponder " << ss[0].pv[1];
if (dbg_show_hit_rate)
dbg_print_hit_rate(LogFile);
- LogFile << "\nNodes: " << nodes_searched()
+ LogFile << "\nNodes: " << TM.nodes_searched()
<< "\nNodes/second: " << nps()
<< "\nBest move: " << move_to_san(p, ss[0].pv[0]);
StateInfo st;
p.do_move(ss[0].pv[0], st);
- LogFile << "\nPonder move: " << move_to_san(p, ss[0].pv[1]) << endl;
+ LogFile << "\nPonder move: "
+ << move_to_san(p, ss[0].pv[1]) // Works also with MOVE_NONE
+ << endl;
}
return rml.get_move_score(0);
}
// root_search() is the function which searches the root node. It is
// similar to search_pv except that it uses a different move ordering
- // scheme and prints some information to the standard output.
+ // scheme, prints some information to the standard output and handles
+ // the fail low/high loops.
- Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta) {
+ Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr) {
- Value alpha = oldAlpha;
- Value value;
- CheckInfo ci(pos);
+ EvalInfo ei;
+ StateInfo st;
+ int64_t nodes;
+ Move move;
+ Depth depth, ext, newDepth;
+ Value value, alpha, beta;
+ bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
int researchCount = 0;
- bool isCheck = pos.is_check();
+ alpha = *alphaPtr;
+ beta = *betaPtr;
+ CheckInfo ci(pos);
+ isCheck = pos.is_check();
- // Evaluate the position statically
- EvalInfo ei;
+ // Step 1. Initialize node and poll (omitted at root, but I can see no good reason for this, FIXME)
+ // Step 2. Check for aborted search (omitted at root, because we do not initialize root node)
+ // Step 3. Mate distance pruning (omitted at root)
+ // Step 4. Transposition table lookup (omitted at root)
+
+ // Step 5. Evaluate the position statically
+ // At root we do this only to get reference value for child nodes
if (!isCheck)
ss[0].eval = evaluate(pos, ei, 0);
else
- ss[0].eval = VALUE_NONE;
+ ss[0].eval = VALUE_NONE; // HACK because we do not initialize root node
- while(1) // Fail low loop
- {
+ // Step 6. Razoring (omitted at root)
+ // Step 7. Static null move pruning (omitted at root)
+ // Step 8. Null move search with verification search (omitted at root)
+ // Step 9. Internal iterative deepening (omitted at root)
- // Loop through all the moves in the root move list
- for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
+ // Step extra. Fail low loop
+ // We start with small aspiration window and in case of fail low, we research
+ // with bigger window until we are not failing low anymore.
+ while (1)
{
- if (alpha >= beta)
- {
- // We failed high, invalidate and skip next moves, leave node-counters
- // and beta-counters as they are and quickly return, we will try to do
- // a research at the next iteration with a bigger aspiration window.
- rml.set_move_score(i, -VALUE_INFINITE);
- continue;
- }
- int64_t nodes;
- Move move;
- StateInfo st;
- Depth depth, ext, newDepth;
-
- RootMoveNumber = i + 1;
- FailHigh = false;
-
- // Save the current node count before the move is searched
- nodes = nodes_searched();
-
- // Reset beta cut-off counters
- BetaCounter.clear();
-
- // Pick the next root move, and print the move and the move number to
- // the standard output.
- move = ss[0].currentMove = rml.get_move(i);
+ // Sort the moves before to (re)search
+ rml.sort();
- if (current_search_time() >= 1000)
- cout << "info currmove " << move
- << " currmovenumber " << RootMoveNumber << endl;
+ // Step 10. Loop through all moves in the root move list
+ for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
+ {
+ // This is used by time management
+ FirstRootMove = (i == 0);
- // Decide search depth for this move
- bool moveIsCheck = pos.move_is_check(move);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
- bool dangerous;
- depth = (Iteration - 2) * OnePly + InitialDepth;
- ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- newDepth = depth + ext;
+ // Save the current node count before the move is searched
+ nodes = TM.nodes_searched();
- value = - VALUE_INFINITE;
+ // Reset beta cut-off counters
+ TM.resetBetaCounters();
- while (1) // Fail high loop
- {
+ // Pick the next root move, and print the move and the move number to
+ // the standard output.
+ move = ss[0].currentMove = rml.get_move(i);
- // Make the move, and search it
- pos.do_move(move, st, ci, moveIsCheck);
+ if (current_search_time() >= 1000)
+ cout << "info currmove " << move
+ << " currmovenumber " << i + 1 << endl;
- if (i < MultiPV || value > alpha)
- {
- // Aspiration window is disabled in multi-pv case
- if (MultiPV > 1)
- alpha = -VALUE_INFINITE;
+ moveIsCheck = pos.move_is_check(move);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+ // Step 11. Decide the new search depth
+ depth = (Iteration - 2) * OnePly + InitialDepth;
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
+ newDepth = depth + ext;
- // If the value has dropped a lot compared to the last iteration,
- // set the boolean variable Problem to true. This variable is used
- // for time managment: When Problem is true, we try to complete the
- // current iteration before playing a move.
- Problem = ( Iteration >= 2
- && value <= IterationInfo[Iteration - 1].value - ProblemMargin);
+ // Step 12. Futility pruning (omitted at root)
- if (Problem && StopOnPonderhit)
- StopOnPonderhit = false;
- }
- else
- {
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
- // if the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( depth >= 3*OnePly // FIXME was newDepth
- && !dangerous
- && !captureOrPromotion
- && !move_is_castle(move))
- {
- ss[0].reduction = calculate_reduction(0.5, RootMoveNumber - MultiPV + 1, depth, 6.0);
- if (ss[0].reduction)
- {
- value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0);
- doFullDepthSearch = (value > alpha);
- }
- }
+ // Step extra. Fail high loop
+ // If move fails high, we research with bigger window until we are not failing
+ // high anymore.
+ value = - VALUE_INFINITE;
- if (doFullDepthSearch)
+ while (1)
{
- ss[0].reduction = Depth(0);
- value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+ // Step 13. Make the move
+ pos.do_move(move, st, ci, moveIsCheck);
- if (value > alpha)
+ // Step extra. pv search
+ // We do pv search for first moves (i < MultiPV)
+ // and for fail high research (value > alpha)
+ if (i < MultiPV || value > alpha)
{
- // Fail high! Set the boolean variable FailHigh to true, and
- // re-search the move using a PV search. The variable FailHigh
- // is used for time managment: We try to avoid aborting the
- // search prematurely during a fail high research.
- FailHigh = true;
+ // Aspiration window is disabled in multi-pv case
+ if (MultiPV > 1)
+ alpha = -VALUE_INFINITE;
+
+ // Full depth PV search, done on first move or after a fail high
value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
}
- }
- }
-
- pos.undo_move(move);
-
- if (AbortSearch || value < beta)
- break; // We are not failing high
-
- // We are failing high and going to do a research. It's important to update score
- // before research in case we run out of time while researching.
- rml.set_move_score(i, value);
- update_pv(ss, 0);
- TT.extract_pv(pos, ss[0].pv, PLY_MAX);
- rml.set_move_pv(i, ss[0].pv);
-
- // Print search information to the standard output
- cout << "info depth " << Iteration
- << " score " << value_to_string(value)
- << ((value >= beta) ? " lowerbound" :
- ((value <= alpha)? " upperbound" : ""))
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv ";
-
- for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
- cout << ss[0].pv[j] << " ";
-
- cout << endl;
-
- if (UseLogFile)
- {
- ValueType type = (value >= beta ? VALUE_TYPE_LOWER
- : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
-
- LogFile << pretty_pv(pos, current_search_time(), Iteration,
- nodes_searched(), value, type, ss[0].pv) << endl;
- }
-
- // Prepare for research
- researchCount++;
- beta = Min(beta + AspirationDelta * (1 << researchCount), VALUE_INFINITE);
-
- } // End of fail high loop
-
- // Finished searching the move. If AbortSearch is true, the search
- // was aborted because the user interrupted the search or because we
- // ran out of time. In this case, the return value of the search cannot
- // be trusted, and we break out of the loop without updating the best
- // move and/or PV.
- if (AbortSearch)
- break;
+ else
+ {
+ // Step 14. Reduced search
+ // if the move fails high will be re-searched at full depth
+ bool doFullDepthSearch = true;
+
+ if ( depth >= 3 * OnePly
+ && !dangerous
+ && !captureOrPromotion
+ && !move_is_castle(move))
+ {
+ ss[0].reduction = pv_reduction(depth, i - MultiPV + 2);
+ if (ss[0].reduction)
+ {
+ // Reduced depth non-pv search using alpha as upperbound
+ value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0);
+ doFullDepthSearch = (value > alpha);
+ }
+ }
+
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
+ {
+ // Full depth non-pv search using alpha as upperbound
+ ss[0].reduction = Depth(0);
+ value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+
+ // If we are above alpha then research at same depth but as PV
+ // to get a correct score or eventually a fail high above beta.
+ if (value > alpha)
+ value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+ }
+ }
- // Remember beta-cutoff and searched nodes counts for this move. The
- // info is used to sort the root moves at the next iteration.
- int64_t our, their;
- BetaCounter.read(pos.side_to_move(), our, their);
- rml.set_beta_counters(i, our, their);
- rml.set_move_nodes(i, nodes_searched() - nodes);
+ // Step 16. Undo move
+ pos.undo_move(move);
- assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+ // Can we exit fail high loop ?
+ if (AbortSearch || value < beta)
+ break;
- if (value <= alpha && i >= MultiPV)
- rml.set_move_score(i, -VALUE_INFINITE);
- else
- {
- // PV move or new best move!
+ // We are failing high and going to do a research. It's important to update
+ // the score before research in case we run out of time while researching.
+ rml.set_move_score(i, value);
+ update_pv(ss, 0);
+ TT.extract_pv(pos, ss[0].pv, PLY_MAX);
+ rml.set_move_pv(i, ss[0].pv);
+
+ // Print information to the standard output
+ print_pv_info(pos, ss, alpha, beta, value);
+
+ // Prepare for a research after a fail high, each time with a wider window
+ researchCount++;
+ *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCount), VALUE_INFINITE);
+
+ } // End of fail high loop
+
+ // Finished searching the move. If AbortSearch is true, the search
+ // was aborted because the user interrupted the search or because we
+ // ran out of time. In this case, the return value of the search cannot
+ // be trusted, and we break out of the loop without updating the best
+ // move and/or PV.
+ if (AbortSearch)
+ break;
+
+ // Remember beta-cutoff and searched nodes counts for this move. The
+ // info is used to sort the root moves for the next iteration.
+ int64_t our, their;
+ TM.get_beta_counters(pos.side_to_move(), our, their);
+ rml.set_beta_counters(i, our, their);
+ rml.set_move_nodes(i, TM.nodes_searched() - nodes);
+
+ assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+ assert(value < beta);
+
+ // Step 17. Check for new best move
+ if (value <= alpha && i >= MultiPV)
+ rml.set_move_score(i, -VALUE_INFINITE);
+ else
+ {
+ // PV move or new best move!
- // Update PV
- rml.set_move_score(i, value);
- update_pv(ss, 0);
- TT.extract_pv(pos, ss[0].pv, PLY_MAX);
- rml.set_move_pv(i, ss[0].pv);
+ // Update PV
+ rml.set_move_score(i, value);
+ update_pv(ss, 0);
+ TT.extract_pv(pos, ss[0].pv, PLY_MAX);
+ rml.set_move_pv(i, ss[0].pv);
- if (MultiPV == 1)
- {
- // We record how often the best move has been changed in each
- // iteration. This information is used for time managment: When
- // the best move changes frequently, we allocate some more time.
- if (i > 0)
- BestMoveChangesByIteration[Iteration]++;
-
- // Print search information to the standard output
- cout << "info depth " << Iteration
- << " score " << value_to_string(value)
- << ((value >= beta) ? " lowerbound" :
- ((value <= alpha)? " upperbound" : ""))
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv ";
-
- for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
- cout << ss[0].pv[j] << " ";
-
- cout << endl;
-
- if (UseLogFile)
+ if (MultiPV == 1)
{
- ValueType type = (value >= beta ? VALUE_TYPE_LOWER
- : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
-
- LogFile << pretty_pv(pos, current_search_time(), Iteration,
- nodes_searched(), value, type, ss[0].pv) << endl;
+ // We record how often the best move has been changed in each
+ // iteration. This information is used for time managment: When
+ // the best move changes frequently, we allocate some more time.
+ if (i > 0)
+ BestMoveChangesByIteration[Iteration]++;
+
+ // Print information to the standard output
+ print_pv_info(pos, ss, alpha, beta, value);
+
+ // Raise alpha to setup proper non-pv search upper bound
+ if (value > alpha)
+ alpha = value;
}
- if (value > alpha)
- alpha = value;
-
- // Reset the global variable Problem to false if the value isn't too
- // far below the final value from the last iteration.
- if (value > IterationInfo[Iteration - 1].value - NoProblemMargin)
- Problem = false;
- }
- else // MultiPV > 1
- {
- rml.sort_multipv(i);
- for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
+ else // MultiPV > 1
{
- cout << "info multipv " << j + 1
- << " score " << value_to_string(rml.get_move_score(j))
- << " depth " << ((j <= i)? Iteration : Iteration - 1)
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv ";
-
- for (int k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
- cout << rml.get_move_pv(j, k) << " ";
-
- cout << endl;
+ rml.sort_multipv(i);
+ for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
+ {
+ cout << "info multipv " << j + 1
+ << " score " << value_to_string(rml.get_move_score(j))
+ << " depth " << (j <= i ? Iteration : Iteration - 1)
+ << " time " << current_search_time()
+ << " nodes " << TM.nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (int k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
+ cout << rml.get_move_pv(j, k) << " ";
+
+ cout << endl;
+ }
+ alpha = rml.get_move_score(Min(i, MultiPV - 1));
}
- alpha = rml.get_move_score(Min(i, MultiPV-1));
- }
- } // PV move or new best move
+ } // PV move or new best move
- assert(alpha >= oldAlpha);
+ assert(alpha >= *alphaPtr);
- FailLow = (alpha == oldAlpha);
- }
+ AspirationFailLow = (alpha == *alphaPtr);
+
+ if (AspirationFailLow && StopOnPonderhit)
+ StopOnPonderhit = false;
+ }
- if (AbortSearch || alpha > oldAlpha)
- break; // End search, we are not failing low
+ // Can we exit fail low loop ?
+ if (AbortSearch || !AspirationFailLow)
+ break;
- // Prepare for research
- researchCount++;
- alpha = Max(alpha - AspirationDelta * (1 << researchCount), -VALUE_INFINITE);
- oldAlpha = alpha;
+ // Prepare for a research after a fail low, each time with a wider window
+ researchCount++;
+ *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCount), -VALUE_INFINITE);
} // Fail low loop
+ // Sort the moves before to return
+ rml.sort();
+
return alpha;
}
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ assert(threadID >= 0 && threadID < TM.active_threads());
Move movesSearched[256];
+ EvalInfo ei;
StateInfo st;
const TTEntry* tte;
Move ttMove, move;
Depth ext, newDepth;
- Value oldAlpha, value;
- bool isCheck, mateThreat, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
+ Value bestValue, value, oldAlpha;
+ bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
+ bool mateThreat = false;
int moveCount = 0;
- Value bestValue = value = -VALUE_INFINITE;
+ bestValue = value = -VALUE_INFINITE;
if (depth < OnePly)
return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
+ // Step 1. Initialize node and poll
+ // Polling can abort search.
init_node(ss, ply, threadID);
- // After init_node() that calls poll()
- if (AbortSearch || thread_should_stop(threadID))
+ // Step 2. Check for aborted search and immediate draw
+ if (AbortSearch || TM.thread_should_stop(threadID))
return Value(0);
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- // Mate distance pruning
+ // Step 3. Mate distance pruning
oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
beta = Min(value_mate_in(ply+1), beta);
if (alpha >= beta)
return alpha;
- // Transposition table lookup. At PV nodes, we don't use the TT for
- // pruning, but only for move ordering. This is to avoid problems in
- // the following areas:
+ // Step 4. Transposition table lookup
+ // At PV nodes, we don't use the TT for pruning, but only for move ordering.
+ // This is to avoid problems in the following areas:
//
// * Repetition draw detection
// * Fifty move rule detection
// * Searching for a mate
// * Printing of full PV line
- //
tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);
- // Go with internal iterative deepening if we don't have a TT move
- if ( UseIIDAtPVNodes
- && depth >= 5*OnePly
+ // Step 5. Evaluate the position statically
+ // At PV nodes we do this only to update gain statistics
+ isCheck = pos.is_check();
+ if (!isCheck)
+ {
+ ss[ply].eval = evaluate(pos, ei, threadID);
+ update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
+ }
+
+ // Step 6. Razoring (is omitted in PV nodes)
+ // Step 7. Static null move pruning (is omitted in PV nodes)
+ // Step 8. Null move search with verification search (is omitted in PV nodes)
+
+ // Step 9. Internal iterative deepening
+ if ( depth >= IIDDepthAtPVNodes
&& ttMove == MOVE_NONE)
{
search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
tte = TT.retrieve(pos.get_key());
}
- isCheck = pos.is_check();
- if (!isCheck)
- {
- // Update gain statistics of the previous move that lead
- // us in this position.
- EvalInfo ei;
- ss[ply].eval = evaluate(pos, ei, threadID);
- update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
- }
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
- // Initialize a MovePicker object for the current position, and prepare
- // to search all moves
+ // Initialize a MovePicker object for the current position
mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
- CheckInfo ci(pos);
MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
+ CheckInfo ci(pos);
- // Loop through all legal moves until no moves remain or a beta cutoff
- // occurs.
while ( alpha < beta
&& (move = mp.get_next_move()) != MOVE_NONE
- && !thread_should_stop(threadID))
+ && !TM.thread_should_stop(threadID))
{
assert(move_is_ok(move));
moveIsCheck = pos.move_is_check(move, ci);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
- // Decide the new search depth
+ // Step 11. Decide the new search depth
ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
// Singular extension search. We extend the TT move if its value is much better than
// its siblings. To verify this we do a reduced search on all the other moves but the
// ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
- if ( depth >= 6 * OnePly
+ if ( depth >= SingularExtensionDepthAtPVNodes
&& tte
&& move == tte->move()
&& ext < OnePly
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
newDepth = depth - OnePly + ext;
- // Update current move
+ // Update current move (this must be done after singular extension search)
movesSearched[moveCount++] = ss[ply].currentMove = move;
- // Make and search the move
+ // Step 12. Futility pruning (is omitted in PV nodes)
+
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- if (moveCount == 1) // The first move in list is the PV
+ // Step extra. pv search (only in PV nodes)
+ // The first move in list is the expected PV
+ if (moveCount == 1)
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
else
{
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
- if ( depth >= 3*OnePly
+ if ( depth >= 3 * OnePly
&& !dangerous
&& !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
- ss[ply].reduction = calculate_reduction(0.5, moveCount, depth, 6.0);
+ ss[ply].reduction = pv_reduction(depth, moveCount);
if (ss[ply].reduction)
{
value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID);
}
}
- if (doFullDepthSearch) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
+
+ // Step extra. pv search (only in PV nodes)
if (value > alpha && value < beta)
- {
- // When the search fails high at ply 1 while searching the first
- // move at the root, set the flag failHighPly1. This is used for
- // time managment: We don't want to stop the search early in
- // such cases, because resolving the fail high at ply 1 could
- // result in a big drop in score at the root.
- if (ply == 1 && RootMoveNumber == 1)
- Threads[threadID].failHighPly1 = true;
-
- // A fail high occurred. Re-search at full window (pv search)
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
- Threads[threadID].failHighPly1 = false;
- }
}
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // New best move?
+ // Step 17. Check for new best move
if (value > bestValue)
{
bestValue = value;
if (value == value_mate_in(ply + 1))
ss[ply].mateKiller = move;
}
- // If we are at ply 1, and we are searching the first root move at
- // ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration.
- if ( ply == 1
- && Iteration >= 2
- && -value <= IterationInfo[Iteration-1].value - ProblemMargin)
- Problem = true;
}
- // Split?
- if ( ActiveThreads > 1
+ // Step 18. Check for split
+ if ( TM.active_threads() > 1
&& bestValue < beta
&& depth >= MinimumSplitDepth
&& Iteration <= 99
- && idle_thread_exists(threadID)
+ && TM.available_thread_exists(threadID)
&& !AbortSearch
- && !thread_should_stop(threadID)
- && split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE,
- depth, &moveCount, &mp, threadID, true))
+ && !TM.thread_should_stop(threadID)
+ && TM.split(pos, ss, ply, &alpha, beta, &bestValue,
+ depth, mateThreat, &moveCount, &mp, threadID, true))
break;
}
- // All legal moves have been searched. A special case: If there were
+ // Step 19. Check for mate and stalemate
+ // All legal moves have been searched and if there were
// no legal moves, it must be mate or stalemate.
if (moveCount == 0)
return (isCheck ? value_mated_in(ply) : VALUE_DRAW);
+ // Step 20. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
- if (AbortSearch || thread_should_stop(threadID))
+ if (AbortSearch || TM.thread_should_stop(threadID))
return bestValue;
if (bestValue <= oldAlpha)
else if (bestValue >= beta)
{
- BetaCounter.add(pos.side_to_move(), depth, threadID);
+ TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
move = ss[ply].pv[ply];
if (!pos.move_is_capture_or_promotion(move))
{
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ assert(threadID >= 0 && threadID < TM.active_threads());
Move movesSearched[256];
EvalInfo ei;
const TTEntry* tte;
Move ttMove, move;
Depth ext, newDepth;
- Value bestValue, staticValue, nullValue, value, futilityValue, futilityValueScaled;
+ Value bestValue, refinedValue, nullValue, value, futilityValueScaled;
bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
bool mateThreat = false;
int moveCount = 0;
- futilityValue = staticValue = bestValue = value = -VALUE_INFINITE;
+ refinedValue = bestValue = value = -VALUE_INFINITE;
if (depth < OnePly)
return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
+ // Step 1. Initialize node and poll
+ // Polling can abort search.
init_node(ss, ply, threadID);
- // After init_node() that calls poll()
- if (AbortSearch || thread_should_stop(threadID))
+ // Step 2. Check for aborted search and immediate draw
+ if (AbortSearch || TM.thread_should_stop(threadID))
return Value(0);
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- // Mate distance pruning
+ // Step 3. Mate distance pruning
if (value_mated_in(ply) >= beta)
return beta;
if (value_mate_in(ply + 1) < beta)
return beta - 1;
+ // Step 4. Transposition table lookup
+
// We don't want the score of a partial search to overwrite a previous full search
- // TT value, so we use a different position key in case of an excluded move exsists.
+ // TT value, so we use a different position key in case of an excluded move exists.
Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
- // Transposition table lookup
tte = TT.retrieve(posKey);
ttMove = (tte ? tte->move() : MOVE_NONE);
return value_from_tt(tte->value(), ply);
}
+ // Step 5. Evaluate the position statically
isCheck = pos.is_check();
- // Calculate depth dependant futility pruning parameters
- const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8));
- const int PostFutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
-
- // Evaluate the position statically
if (!isCheck)
{
if (tte && (tte->type() & VALUE_TYPE_EVAL))
- staticValue = value_from_tt(tte->value(), ply);
+ ss[ply].eval = value_from_tt(tte->value(), ply);
else
- {
- staticValue = evaluate(pos, ei, threadID);
- ss[ply].evalInfo = &ei;
- }
+ ss[ply].eval = evaluate(pos, ei, threadID);
- ss[ply].eval = staticValue;
- futilityValue = staticValue + PostFutilityValueMargin; //FIXME: Remove me, only for split
- staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible
+ refinedValue = refine_eval(tte, ss[ply].eval, ply); // Enhance accuracy with TT value if possible
update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
}
- // Do a "stand pat". If we are above beta by a good margin then
- // return immediately.
- // FIXME: test with added condition 'allowNullmove || depth <= OnePly' and !value_is_mate(beta)
- // FIXME: test with modified condition 'depth < RazorDepth'
- if ( !isCheck
- && depth < SelectiveDepth
- && staticValue - PostFutilityValueMargin >= beta)
- return staticValue - PostFutilityValueMargin;
+ // Step 6. Razoring
+ if ( !value_is_mate(beta)
+ && !isCheck
+ && depth < RazorDepth
+ && refinedValue < beta - razor_margin(depth)
+ && ss[ply - 1].currentMove != MOVE_NULL
+ && ttMove == MOVE_NONE
+ && !pos.has_pawn_on_7th(pos.side_to_move()))
+ {
+ Value rbeta = beta - razor_margin(depth);
+ Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
+ if (v < rbeta)
+ // Logically we should return (v + razor_margin(depth)), but
+ // surprisingly this did slightly weaker in tests.
+ return v;
+ }
- // Null move search
+ // Step 7. Static null move pruning
+ // We're betting that the opponent doesn't have a move that will reduce
+ // the score by more than fuility_margin(depth) if we do a null move.
+ if ( !isCheck
+ && allowNullmove
+ && depth < RazorDepth
+ && refinedValue - futility_margin(depth, 0) >= beta)
+ return refinedValue - futility_margin(depth, 0);
+
+ // Step 8. Null move search with verification search
+ // When we jump directly to qsearch() we do a null move only if static value is
+ // at least beta. Otherwise we do a null move if static value is not more than
+ // NullMoveMargin under beta.
if ( allowNullmove
&& depth > OnePly
&& !isCheck
&& !value_is_mate(beta)
&& ok_to_do_nullmove(pos)
- && staticValue >= beta - NullMoveMargin)
+ && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0))
{
ss[ply].currentMove = MOVE_NULL;
int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0);
// Null move dynamic reduction based on value
- if (staticValue - beta > PawnValueMidgame)
+ if (refinedValue - beta > PawnValueMidgame)
R++;
nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
return beta - 1;
}
}
- // Null move search not allowed, try razoring
- else if ( !value_is_mate(beta)
- && !isCheck
- && depth < RazorDepth
- && staticValue < beta - (NullMoveMargin + 16 * depth)
- && ss[ply - 1].currentMove != MOVE_NULL
- && ttMove == MOVE_NONE
- && !pos.has_pawn_on_7th(pos.side_to_move()))
- {
- Value rbeta = beta - (NullMoveMargin + 16 * depth);
- Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
- if (v < rbeta)
- return v;
- }
- // Go with internal iterative deepening if we don't have a TT move
- if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
- !isCheck && ss[ply].eval >= beta - IIDMargin)
+ // Step 9. Internal iterative deepening
+ if ( depth >= IIDDepthAtNonPVNodes
+ && ttMove == MOVE_NONE
+ && !isCheck
+ && ss[ply].eval >= beta - IIDMargin)
{
- search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
+ search(pos, ss, beta, depth/2, ply, false, threadID);
ttMove = ss[ply].pv[ply];
- tte = TT.retrieve(pos.get_key());
+ tte = TT.retrieve(posKey);
}
- // Initialize a MovePicker object for the current position, and prepare
- // to search all moves.
- MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
+
+ // Initialize a MovePicker object for the current position
+ MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta);
CheckInfo ci(pos);
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
&& (move = mp.get_next_move()) != MOVE_NONE
- && !thread_should_stop(threadID))
+ && !TM.thread_should_stop(threadID))
{
assert(move_is_ok(move));
singleEvasion = (isCheck && mp.number_of_evasions() == 1);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
- // Decide the new search depth
+ // Step 11. Decide the new search depth
ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
// Singular extension search. We extend the TT move if its value is much better than
// its siblings. To verify this we do a reduced search on all the other moves but the
// ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
- if ( depth >= 8 * OnePly
+ if ( depth >= SingularExtensionDepthAtNonPVNodes
&& tte
&& move == tte->move()
&& !excludedMove // Do not allow recursive single-reply search
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
newDepth = depth - OnePly + ext;
- // Update current move
+ // Update current move (this must be done after singular extension search)
movesSearched[moveCount++] = ss[ply].currentMove = move;
- // Futility pruning for captures
- // FIXME: test disabling 'Futility pruning for captures'
- // FIXME: test with 'newDepth < RazorDepth'
- Color them = opposite_color(pos.side_to_move());
-
- if ( !isCheck
- && newDepth < SelectiveDepth
- && !dangerous
- && pos.move_is_capture(move)
- && !pos.move_is_check(move, ci)
- && !move_is_promotion(move)
- && move != ttMove
- && !move_is_ep(move)
- && (pos.type_of_piece_on(move_to(move)) != PAWN || !pos.pawn_is_passed(them, move_to(move)))) // Do not prune passed pawn captures
- {
- int preFutilityValueMargin = 0;
-
- if (newDepth >= OnePly)
- preFutilityValueMargin = 112 * bitScanReverse32(int(newDepth) * int(newDepth) / 2);
-
- Value futilityCaptureValue = ss[ply].eval + pos.endgame_value_of_piece_on(move_to(move)) + preFutilityValueMargin + ei.futilityMargin + 90;
-
- if (futilityCaptureValue < beta)
- {
- if (futilityCaptureValue > bestValue)
- bestValue = futilityCaptureValue;
- continue;
- }
- }
-
- // Futility pruning
+ // Step 12. Futility pruning
if ( !isCheck
&& !dangerous
&& !captureOrPromotion
&& move != ttMove)
{
// Move count based pruning
- if ( moveCount >= FutilityMoveCountMargin
+ if ( moveCount >= futility_move_count(depth)
&& ok_to_prune(pos, move, ss[ply].threatMove)
&& bestValue > value_mated_in(PLY_MAX))
continue;
// Value based pruning
- Depth predictedDepth = newDepth;
-
- //FIXME: We are ignoring condition: depth >= 3*OnePly, BUG??
- ss[ply].reduction = calculate_reduction(0.5, moveCount, depth, 3.0);
- if (ss[ply].reduction)
- predictedDepth -= ss[ply].reduction;
+ Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly
+ futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount)
+ + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45;
- if (predictedDepth < SelectiveDepth)
+ if (futilityValueScaled < beta)
{
- int preFutilityValueMargin = 0;
- if (predictedDepth >= OnePly)
- preFutilityValueMargin = 112 * bitScanReverse32(int(predictedDepth) * int(predictedDepth) / 2);
-
- preFutilityValueMargin += H.gain(pos.piece_on(move_from(move)), move_from(move), move_to(move)) + 45;
-
- futilityValueScaled = ss[ply].eval + preFutilityValueMargin - moveCount * IncrementalFutilityMargin;
-
- if (futilityValueScaled < beta)
- {
- if (futilityValueScaled > bestValue)
- bestValue = futilityValueScaled;
- continue;
- }
+ if (futilityValueScaled > bestValue)
+ bestValue = futilityValueScaled;
+ continue;
}
}
- // Make and search the move
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
- ss[ply].reduction = calculate_reduction(0.5, moveCount, depth, 3.0);
+ ss[ply].reduction = nonpv_reduction(depth, moveCount);
if (ss[ply].reduction)
{
value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID);
}
}
- if (doFullDepthSearch) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // New best move?
+ // Step 17. Check for new best move
if (value > bestValue)
{
bestValue = value;
ss[ply].mateKiller = move;
}
- // Split?
- if ( ActiveThreads > 1
+ // Step 18. Check for split
+ if ( TM.active_threads() > 1
&& bestValue < beta
&& depth >= MinimumSplitDepth
&& Iteration <= 99
- && idle_thread_exists(threadID)
+ && TM.available_thread_exists(threadID)
&& !AbortSearch
- && !thread_should_stop(threadID)
- && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, //FIXME: SMP & futilityValue
- depth, &moveCount, &mp, threadID, false))
+ && !TM.thread_should_stop(threadID)
+ && TM.split(pos, ss, ply, NULL, beta, &bestValue,
+ depth, mateThreat, &moveCount, &mp, threadID, false))
break;
}
- // All legal moves have been searched. A special case: If there were
+ // Step 19. Check for mate and stalemate
+ // All legal moves have been searched and if there were
// no legal moves, it must be mate or stalemate.
+ // If one move was excluded return fail low.
if (!moveCount)
return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
+ // Step 20. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
- if (AbortSearch || thread_should_stop(threadID))
+ if (AbortSearch || TM.thread_should_stop(threadID))
return bestValue;
if (bestValue < beta)
TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
else
{
- BetaCounter.add(pos.side_to_move(), depth, threadID);
+ TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
move = ss[ply].pv[ply];
TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
if (!pos.move_is_capture_or_promotion(move))
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(depth <= 0);
assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ assert(threadID >= 0 && threadID < TM.active_threads());
EvalInfo ei;
StateInfo st;
const TTEntry* tte = NULL;
int moveCount = 0;
bool pvNode = (beta - alpha != 1);
+ Value oldAlpha = alpha;
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
init_node(ss, ply, threadID);
// After init_node() that calls poll()
- if (AbortSearch || thread_should_stop(threadID))
+ if (AbortSearch || TM.thread_should_stop(threadID))
return Value(0);
if (pos.is_draw() || ply >= PLY_MAX - 1)
if (bestValue >= beta)
{
// Store the score to avoid a future costly evaluation() call
- if (!isCheck && !tte && ei.futilityMargin == 0)
+ if (!isCheck && !tte && ei.futilityMargin[pos.side_to_move()] == 0)
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE);
return bestValue;
MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H);
CheckInfo ci(pos);
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
- futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin;
+ futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()];
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
// Don't search moves with negative SEE values
if ( (!isCheck || evasionPrunable)
+ && !pvNode
&& move != ttMove
&& !move_is_promotion(move)
&& pos.see_sign(move) < 0)
// Update transposition table
Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
- if (bestValue < beta)
+ if (bestValue <= oldAlpha)
{
// If bestValue isn't changed it means it is still the static evaluation
// of the node, so keep this info to avoid a future evaluation() call.
- ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
+ ValueType type = (bestValue == staticValue && !ei.futilityMargin[pos.side_to_move()] ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
}
- else
+ else if (bestValue >= beta)
{
move = ss[ply].pv[ply];
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
if (!pos.move_is_capture_or_promotion(move))
update_killers(move, ss[ply]);
}
+ else
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss[ply].pv[ply]);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
void sp_search(SplitPoint* sp, int threadID) {
- assert(threadID >= 0 && threadID < ActiveThreads);
- assert(ActiveThreads > 1);
+ assert(threadID >= 0 && threadID < TM.active_threads());
+ assert(TM.active_threads() > 1);
+
+ StateInfo st;
+ Move move;
+ Depth ext, newDepth;
+ Value value, futilityValueScaled;
+ bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
+ int moveCount;
+ value = -VALUE_INFINITE;
Position pos(*sp->pos);
CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
- Value value = -VALUE_INFINITE;
- Move move;
- int moveCount;
- bool isCheck = pos.is_check();
- bool useFutilityPruning = sp->depth < SelectiveDepth
- && !isCheck;
+ isCheck = pos.is_check();
- const int FutilityMoveCountMargin = 3 + (1 << (3 * int(sp->depth) / 8));
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ lock_grab(&(sp->lock));
- while ( lock_grab_bool(&(sp->lock))
- && sp->bestValue < sp->beta
- && !thread_should_stop(threadID)
+ while ( sp->bestValue < sp->beta
+ && !TM.thread_should_stop(threadID)
&& (move = sp->mp->get_next_move()) != MOVE_NONE)
{
moveCount = ++sp->moves;
assert(move_is_ok(move));
- bool moveIsCheck = pos.move_is_check(move, ci);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ moveIsCheck = pos.move_is_check(move, ci);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
- ss[sp->ply].currentMove = move;
+ // Step 11. Decide the new search depth
+ ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
+ newDepth = sp->depth - OnePly + ext;
- // Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- Depth newDepth = sp->depth - OnePly + ext;
+ // Update current move
+ ss[sp->ply].currentMove = move;
- // Prune?
- if ( useFutilityPruning
+ // Step 12. Futility pruning
+ if ( !isCheck
&& !dangerous
- && !captureOrPromotion)
+ && !captureOrPromotion
+ && !move_is_castle(move))
{
// Move count based pruning
- if ( moveCount >= FutilityMoveCountMargin
+ if ( moveCount >= futility_move_count(sp->depth)
&& ok_to_prune(pos, move, ss[sp->ply].threatMove)
&& sp->bestValue > value_mated_in(PLY_MAX))
+ {
+ lock_grab(&(sp->lock));
continue;
+ }
// Value based pruning
- Value futilityValueScaled = sp->futilityValue - moveCount * IncrementalFutilityMargin;
+ Depth predictedDepth = newDepth - nonpv_reduction(sp->depth, moveCount);
+ futilityValueScaled = ss[sp->ply].eval + futility_margin(predictedDepth, moveCount)
+ + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45;
if (futilityValueScaled < sp->beta)
{
- if (futilityValueScaled > sp->bestValue) // Less then 1% of cases
- {
- lock_grab(&(sp->lock));
- if (futilityValueScaled > sp->bestValue)
- sp->bestValue = futilityValueScaled;
- lock_release(&(sp->lock));
- }
+ lock_grab(&(sp->lock));
+
+ if (futilityValueScaled > sp->bestValue)
+ sp->bestValue = futilityValueScaled;
continue;
}
}
- // Make and search the move.
- StateInfo st;
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
- ss[sp->ply].reduction = calculate_reduction(0.5, moveCount, sp->depth, 3.0);
+ ss[sp->ply].reduction = nonpv_reduction(sp->depth, moveCount);
if (ss[sp->ply].reduction)
{
value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
- doFullDepthSearch = (value >= sp->beta);
+ doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID));
}
}
- if (doFullDepthSearch) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
ss[sp->ply].reduction = Depth(0);
value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID);
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- if (thread_should_stop(threadID))
- {
- lock_grab(&(sp->lock));
- break;
- }
+ // Step 17. Check for new best move
+ lock_grab(&(sp->lock));
- // New best move?
- if (value > sp->bestValue) // Less then 2% of cases
+ if (value > sp->bestValue && !TM.thread_should_stop(threadID))
{
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !thread_should_stop(threadID))
+ sp->bestValue = value;
+ if (sp->bestValue >= sp->beta)
{
- sp->bestValue = value;
- if (sp->bestValue >= sp->beta)
- {
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- for (int i = 0; i < ActiveThreads; i++)
- if (i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
-
- sp->finished = true;
- }
+ sp->stopRequest = true;
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
}
- lock_release(&(sp->lock));
}
}
/* Here we have the lock still grabbed */
- // If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads.
- if (sp->master == threadID && thread_should_stop(threadID))
- for (int i = 0; i < ActiveThreads; i++)
- if (sp->slaves[i])
- Threads[i].stop = true;
-
- sp->cpus--;
sp->slaves[threadID] = 0;
+ sp->cpus--;
lock_release(&(sp->lock));
}
void sp_search_pv(SplitPoint* sp, int threadID) {
- assert(threadID >= 0 && threadID < ActiveThreads);
- assert(ActiveThreads > 1);
+ assert(threadID >= 0 && threadID < TM.active_threads());
+ assert(TM.active_threads() > 1);
+
+ StateInfo st;
+ Move move;
+ Depth ext, newDepth;
+ Value value;
+ bool moveIsCheck, captureOrPromotion, dangerous;
+ int moveCount;
+ value = -VALUE_INFINITE;
Position pos(*sp->pos);
CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
- Value value = -VALUE_INFINITE;
- int moveCount;
- Move move;
- while ( lock_grab_bool(&(sp->lock))
- && sp->alpha < sp->beta
- && !thread_should_stop(threadID)
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ lock_grab(&(sp->lock));
+
+ while ( sp->alpha < sp->beta
+ && !TM.thread_should_stop(threadID)
&& (move = sp->mp->get_next_move()) != MOVE_NONE)
{
moveCount = ++sp->moves;
assert(move_is_ok(move));
- bool moveIsCheck = pos.move_is_check(move, ci);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ moveIsCheck = pos.move_is_check(move, ci);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
+
+ // Step 11. Decide the new search depth
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
+ newDepth = sp->depth - OnePly + ext;
+ // Update current move
ss[sp->ply].currentMove = move;
- // Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- Depth newDepth = sp->depth - OnePly + ext;
+ // Step 12. Futility pruning (is omitted in PV nodes)
- // Make and search the move.
- StateInfo st;
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
- ss[sp->ply].reduction = calculate_reduction(0.5, moveCount, sp->depth, 6.0);
+ ss[sp->ply].reduction = pv_reduction(sp->depth, moveCount);
if (ss[sp->ply].reduction)
{
Value localAlpha = sp->alpha;
value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
- doFullDepthSearch = (value > localAlpha);
+ doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID));
}
}
- if (doFullDepthSearch) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
Value localAlpha = sp->alpha;
ss[sp->ply].reduction = Depth(0);
value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID);
- if (value > localAlpha && value < sp->beta)
+ if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID))
{
- // When the search fails high at ply 1 while searching the first
- // move at the root, set the flag failHighPly1. This is used for
- // time managment: We don't want to stop the search early in
- // such cases, because resolving the fail high at ply 1 could
- // result in a big drop in score at the root.
- if (sp->ply == 1 && RootMoveNumber == 1)
- Threads[threadID].failHighPly1 = true;
-
// If another thread has failed high then sp->alpha has been increased
// to be higher or equal then beta, if so, avoid to start a PV search.
localAlpha = sp->alpha;
if (localAlpha < sp->beta)
value = -search_pv(pos, ss, -sp->beta, -localAlpha, newDepth, sp->ply+1, threadID);
- else
- assert(thread_should_stop(threadID));
-
- Threads[threadID].failHighPly1 = false;
- }
+ }
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- if (thread_should_stop(threadID))
- {
- lock_grab(&(sp->lock));
- break;
- }
+ // Step 17. Check for new best move
+ lock_grab(&(sp->lock));
- // New best move?
- if (value > sp->bestValue) // Less then 2% of cases
+ if (value > sp->bestValue && !TM.thread_should_stop(threadID))
{
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !thread_should_stop(threadID))
+ sp->bestValue = value;
+ if (value > sp->alpha)
{
- sp->bestValue = value;
- if (value > sp->alpha)
- {
- // Ask threads to stop before to modify sp->alpha
- if (value >= sp->beta)
- {
- for (int i = 0; i < ActiveThreads; i++)
- if (i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
-
- sp->finished = true;
- }
-
- sp->alpha = value;
-
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- if (value == value_mate_in(sp->ply + 1))
- ss[sp->ply].mateKiller = move;
- }
- // If we are at ply 1, and we are searching the first root move at
- // ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration.
- if ( sp->ply == 1
- && Iteration >= 2
- && -value <= IterationInfo[Iteration-1].value - ProblemMargin)
- Problem = true;
+ // Ask threads to stop before to modify sp->alpha
+ if (value >= sp->beta)
+ sp->stopRequest = true;
+
+ sp->alpha = value;
+
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
+ if (value == value_mate_in(sp->ply + 1))
+ ss[sp->ply].mateKiller = move;
}
- lock_release(&(sp->lock));
}
}
/* Here we have the lock still grabbed */
- // If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads.
- if (sp->master == threadID && thread_should_stop(threadID))
- for (int i = 0; i < ActiveThreads; i++)
- if (sp->slaves[i])
- Threads[i].stop = true;
-
- sp->cpus--;
sp->slaves[threadID] = 0;
+ sp->cpus--;
lock_release(&(sp->lock));
}
- /// The BetaCounterType class
-
- BetaCounterType::BetaCounterType() { clear(); }
-
- void BetaCounterType::clear() {
-
- for (int i = 0; i < THREAD_MAX; i++)
- Threads[i].betaCutOffs[WHITE] = Threads[i].betaCutOffs[BLACK] = 0ULL;
- }
-
- void BetaCounterType::add(Color us, Depth d, int threadID) {
-
- // Weighted count based on depth
- Threads[threadID].betaCutOffs[us] += unsigned(d);
- }
-
- void BetaCounterType::read(Color us, int64_t& our, int64_t& their) {
-
- our = their = 0UL;
- for (int i = 0; i < THREAD_MAX; i++)
- {
- our += Threads[i].betaCutOffs[us];
- their += Threads[i].betaCutOffs[opposite_color(us)];
- }
- }
-
-
- /// The RootMoveList class
-
- // RootMoveList c'tor
-
- RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) {
-
- MoveStack mlist[MaxRootMoves];
- bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
-
- // Generate all legal moves
- MoveStack* last = generate_moves(pos, mlist);
-
- // Add each move to the moves[] array
- for (MoveStack* cur = mlist; cur != last; cur++)
- {
- bool includeMove = includeAllMoves;
-
- for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
- includeMove = (searchMoves[k] == cur->move);
-
- if (!includeMove)
- continue;
-
- // Find a quick score for the move
- StateInfo st;
- SearchStack ss[PLY_MAX_PLUS_2];
- init_ss_array(ss);
-
- moves[count].move = cur->move;
- pos.do_move(moves[count].move, st);
- moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
- pos.undo_move(moves[count].move);
- moves[count].pv[0] = moves[count].move;
- moves[count].pv[1] = MOVE_NONE;
- count++;
- }
- sort();
- }
-
-
- // RootMoveList simple methods definitions
-
- void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) {
-
- moves[moveNum].nodes = nodes;
- moves[moveNum].cumulativeNodes += nodes;
- }
-
- void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
-
- moves[moveNum].ourBeta = our;
- moves[moveNum].theirBeta = their;
- }
-
- void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
-
- int j;
-
- for (j = 0; pv[j] != MOVE_NONE; j++)
- moves[moveNum].pv[j] = pv[j];
-
- moves[moveNum].pv[j] = MOVE_NONE;
- }
-
-
- // RootMoveList::sort() sorts the root move list at the beginning of a new
- // iteration.
-
- void RootMoveList::sort() {
-
- sort_multipv(count - 1); // Sort all items
- }
-
-
- // RootMoveList::sort_multipv() sorts the first few moves in the root move
- // list by their scores and depths. It is used to order the different PVs
- // correctly in MultiPV mode.
-
- void RootMoveList::sort_multipv(int n) {
-
- int i,j;
-
- for (i = 1; i <= n; i++)
- {
- RootMove rm = moves[i];
- for (j = i; j > 0 && moves[j - 1] < rm; j--)
- moves[j] = moves[j - 1];
-
- moves[j] = rm;
- }
- }
-
// init_node() is called at the beginning of all the search functions
// (search(), search_pv(), qsearch(), and so on) and initializes the
void init_node(SearchStack ss[], int ply, int threadID) {
assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ assert(threadID >= 0 && threadID < TM.active_threads());
- Threads[threadID].nodes++;
+ TM.incrementNodeCounter(threadID);
if (threadID == 0)
{
NodesSincePoll++;
if (NodesSincePoll >= NodesBetweenPolls)
{
- poll();
+ poll(ss, ply);
NodesSincePoll = 0;
}
}
ss[ply].init(ply);
ss[ply + 2].initKillers();
-
- if (Threads[threadID].printCurrentLine)
- print_current_line(ss, ply, threadID);
}
return defaultEval;
}
- // calculate_reduction() returns reduction in plies based on
- // moveCount and depth. Reduction is always at least one ply.
-
- Depth calculate_reduction(double baseReduction, int moveCount, Depth depth, double reductionInhibitor) {
-
- double red = baseReduction + ln(moveCount) * ln(depth / 2) / reductionInhibitor;
-
- if (red >= 1.0)
- return Depth(int(floor(red * int(OnePly))));
- else
- return Depth(0);
-
- }
// update_history() registers a good move that produced a beta-cutoff
// in history and marks as failures all the other moves of that ply.
&& pos.captured_piece() == NO_PIECE_TYPE
&& !move_is_castle(m)
&& !move_is_promotion(m))
- H.set_gain(pos.piece_on(move_to(m)), move_from(m), move_to(m), -(before + after));
- }
-
-
- // fail_high_ply_1() checks if some thread is currently resolving a fail
- // high at ply 1 at the node below the first root node. This information
- // is used for time management.
-
- bool fail_high_ply_1() {
-
- for (int i = 0; i < ActiveThreads; i++)
- if (Threads[i].failHighPly1)
- return true;
-
- return false;
+ H.set_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after));
}
int nps() {
int t = current_search_time();
- return (t > 0 ? int((nodes_searched() * 1000) / t) : 0);
+ return (t > 0 ? int((TM.nodes_searched() * 1000) / t) : 0);
}
// looks at the time consumed so far and decides if it's time to abort the
// search.
- void poll() {
+ void poll(SearchStack ss[], int ply) {
static int lastInfoTime;
int t = current_search_time();
else if (t - lastInfoTime >= 1000)
{
lastInfoTime = t;
- lock_grab(&IOLock);
if (dbg_show_mean)
dbg_print_mean();
if (dbg_show_hit_rate)
dbg_print_hit_rate();
- cout << "info nodes " << nodes_searched() << " nps " << nps()
+ cout << "info nodes " << TM.nodes_searched() << " nps " << nps()
<< " time " << t << " hashfull " << TT.full() << endl;
- lock_release(&IOLock);
+ // We only support current line printing in single thread mode
+ if (ShowCurrentLine && TM.active_threads() == 1)
+ {
+ cout << "info currline";
+ for (int p = 0; p < ply; p++)
+ cout << " " << ss[p].currentMove;
- if (ShowCurrentLine)
- Threads[0].printCurrentLine = true;
+ cout << endl;
+ }
}
// Should we stop the search?
if (PonderSearch)
return;
- bool stillAtFirstMove = RootMoveNumber == 1
- && !FailLow
+ bool stillAtFirstMove = FirstRootMove
+ && !AspirationFailLow
&& t > MaxSearchTime + ExtraSearchTime;
- bool noProblemFound = !FailHigh
- && !FailLow
- && !fail_high_ply_1()
- && !Problem
- && t > 6 * (MaxSearchTime + ExtraSearchTime);
-
bool noMoreTime = t > AbsoluteMaxSearchTime
- || stillAtFirstMove //FIXME: We are not checking any problem flags, BUG?
- || noProblemFound;
+ || stillAtFirstMove;
if ( (Iteration >= 3 && UseTimeManagement && noMoreTime)
|| (ExactMaxTime && t >= ExactMaxTime)
- || (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
+ || (Iteration >= 3 && MaxNodes && TM.nodes_searched() >= MaxNodes))
AbortSearch = true;
}
int t = current_search_time();
PonderSearch = false;
- bool stillAtFirstMove = RootMoveNumber == 1
- && !FailLow
+ bool stillAtFirstMove = FirstRootMove
+ && !AspirationFailLow
&& t > MaxSearchTime + ExtraSearchTime;
- bool noProblemFound = !FailHigh
- && !FailLow
- && !fail_high_ply_1()
- && !Problem
- && t > 6 * (MaxSearchTime + ExtraSearchTime);
-
bool noMoreTime = t > AbsoluteMaxSearchTime
- || stillAtFirstMove
- || noProblemFound;
+ || stillAtFirstMove;
if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit))
AbortSearch = true;
}
- // print_current_line() prints the current line of search for a given
- // thread. Called when the UCI option UCI_ShowCurrLine is 'true'.
-
- void print_current_line(SearchStack ss[], int ply, int threadID) {
-
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
-
- if (!Threads[threadID].idle)
- {
- lock_grab(&IOLock);
- cout << "info currline " << (threadID + 1);
- for (int p = 0; p < ply; p++)
- cout << " " << ss[p].currentMove;
-
- cout << endl;
- lock_release(&IOLock);
- }
- Threads[threadID].printCurrentLine = false;
- if (threadID + 1 < ActiveThreads)
- Threads[threadID + 1].printCurrentLine = true;
- }
-
-
// init_ss_array() does a fast reset of the first entries of a SearchStack array
void init_ss_array(SearchStack ss[]) {
}
+ // print_pv_info() prints to standard output and eventually to log file information on
+ // the current PV line. It is called at each iteration or after a new pv is found.
+
+ void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value) {
+
+ cout << "info depth " << Iteration
+ << " score " << value_to_string(value)
+ << ((value >= beta) ? " lowerbound" :
+ ((value <= alpha)? " upperbound" : ""))
+ << " time " << current_search_time()
+ << " nodes " << TM.nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
+ cout << ss[0].pv[j] << " ";
+
+ cout << endl;
+
+ if (UseLogFile)
+ {
+ ValueType type = (value >= beta ? VALUE_TYPE_LOWER
+ : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
+
+ LogFile << pretty_pv(pos, current_search_time(), Iteration,
+ TM.nodes_searched(), value, type, ss[0].pv) << endl;
+ }
+ }
+
+
+ // init_thread() is the function which is called when a new thread is
+ // launched. It simply calls the idle_loop() function with the supplied
+ // threadID. There are two versions of this function; one for POSIX
+ // threads and one for Windows threads.
+
+#if !defined(_MSC_VER)
+
+ void* init_thread(void *threadID) {
+
+ TM.idle_loop(*(int*)threadID, NULL);
+ return NULL;
+ }
+
+#else
+
+ DWORD WINAPI init_thread(LPVOID threadID) {
+
+ TM.idle_loop(*(int*)threadID, NULL);
+ return 0;
+ }
+
+#endif
+
+
+ /// The ThreadsManager class
+
+ // resetNodeCounters(), resetBetaCounters(), searched_nodes() and
+ // get_beta_counters() are getters/setters for the per thread
+ // counters used to sort the moves at root.
+
+ void ThreadsManager::resetNodeCounters() {
+
+ for (int i = 0; i < MAX_THREADS; i++)
+ threads[i].nodes = 0ULL;
+ }
+
+ void ThreadsManager::resetBetaCounters() {
+
+ for (int i = 0; i < MAX_THREADS; i++)
+ threads[i].betaCutOffs[WHITE] = threads[i].betaCutOffs[BLACK] = 0ULL;
+ }
+
+ int64_t ThreadsManager::nodes_searched() const {
+
+ int64_t result = 0ULL;
+ for (int i = 0; i < ActiveThreads; i++)
+ result += threads[i].nodes;
+
+ return result;
+ }
+
+ void ThreadsManager::get_beta_counters(Color us, int64_t& our, int64_t& their) const {
+
+ our = their = 0UL;
+ for (int i = 0; i < MAX_THREADS; i++)
+ {
+ our += threads[i].betaCutOffs[us];
+ their += threads[i].betaCutOffs[opposite_color(us)];
+ }
+ }
+
+
// idle_loop() is where the threads are parked when they have no work to do.
// The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint
// object for which the current thread is the master.
- void idle_loop(int threadID, SplitPoint* waitSp) {
+ void ThreadsManager::idle_loop(int threadID, SplitPoint* waitSp) {
- assert(threadID >= 0 && threadID < THREAD_MAX);
-
- Threads[threadID].running = true;
+ assert(threadID >= 0 && threadID < MAX_THREADS);
while (true)
{
- if (AllThreadsShouldExit && threadID != 0)
- break;
+ // Slave threads can exit as soon as AllThreadsShouldExit raises,
+ // master should exit as last one.
+ if (AllThreadsShouldExit)
+ {
+ assert(!waitSp);
+ threads[threadID].state = THREAD_TERMINATED;
+ return;
+ }
// If we are not thinking, wait for a condition to be signaled
// instead of wasting CPU time polling for work.
- while (threadID != 0 && (Idle || threadID >= ActiveThreads))
+ while (AllThreadsShouldSleep || threadID >= ActiveThreads)
{
+ assert(!waitSp);
+ assert(threadID != 0);
+ threads[threadID].state = THREAD_SLEEPING;
#if !defined(_MSC_VER)
- pthread_mutex_lock(&WaitLock);
- if (Idle || threadID >= ActiveThreads)
+ lock_grab(&WaitLock);
+ if (AllThreadsShouldSleep || threadID >= ActiveThreads)
pthread_cond_wait(&WaitCond, &WaitLock);
-
- pthread_mutex_unlock(&WaitLock);
+ lock_release(&WaitLock);
#else
WaitForSingleObject(SitIdleEvent[threadID], INFINITE);
#endif
}
- // If this thread has been assigned work, launch a search
- if (Threads[threadID].workIsWaiting)
- {
- assert(!Threads[threadID].idle);
+ // If thread has just woken up, mark it as available
+ if (threads[threadID].state == THREAD_SLEEPING)
+ threads[threadID].state = THREAD_AVAILABLE;
- Threads[threadID].workIsWaiting = false;
- if (Threads[threadID].splitPoint->pvNode)
- sp_search_pv(Threads[threadID].splitPoint, threadID);
- else
- sp_search(Threads[threadID].splitPoint, threadID);
+ // If this thread has been assigned work, launch a search
+ if (threads[threadID].state == THREAD_WORKISWAITING)
+ {
+ assert(!AllThreadsShouldExit && !AllThreadsShouldSleep);
- Threads[threadID].idle = true;
- }
+ threads[threadID].state = THREAD_SEARCHING;
- // If this thread is the master of a split point and all threads have
- // finished their work at this split point, return from the idle loop.
- if (waitSp != NULL && waitSp->cpus == 0)
- return;
- }
+ if (threads[threadID].splitPoint->pvNode)
+ sp_search_pv(threads[threadID].splitPoint, threadID);
+ else
+ sp_search(threads[threadID].splitPoint, threadID);
+
+ assert(threads[threadID].state == THREAD_SEARCHING);
+
+ threads[threadID].state = THREAD_AVAILABLE;
+ }
- Threads[threadID].running = false;
+ // If this thread is the master of a split point and all threads have
+ // finished their work at this split point, return from the idle loop.
+ if (waitSp != NULL && waitSp->cpus == 0)
+ {
+ assert(threads[threadID].state == THREAD_AVAILABLE);
+
+ threads[threadID].state = THREAD_SEARCHING;
+ return;
+ }
+ }
}
- // init_split_point_stack() is called during program initialization, and
- // initializes all split point objects.
+ // init_threads() is called during startup. It launches all helper threads,
+ // and initializes the split point stack and the global locks and condition
+ // objects.
+
+ void ThreadsManager::init_threads() {
+
+ volatile int i;
+ bool ok;
+
+#if !defined(_MSC_VER)
+ pthread_t pthread[1];
+#endif
+
+ // Initialize global locks
+ lock_init(&MPLock, NULL);
+ lock_init(&WaitLock, NULL);
- void init_split_point_stack() {
+#if !defined(_MSC_VER)
+ pthread_cond_init(&WaitCond, NULL);
+#else
+ for (i = 0; i < MAX_THREADS; i++)
+ SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
+#endif
- for (int i = 0; i < THREAD_MAX; i++)
+ // Initialize SplitPointStack locks
+ for (i = 0; i < MAX_THREADS; i++)
for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
{
SplitPointStack[i][j].parent = NULL;
lock_init(&(SplitPointStack[i][j].lock), NULL);
}
+
+ // Will be set just before program exits to properly end the threads
+ AllThreadsShouldExit = false;
+
+ // Threads will be put to sleep as soon as created
+ AllThreadsShouldSleep = true;
+
+ // All threads except the main thread should be initialized to THREAD_AVAILABLE
+ ActiveThreads = 1;
+ threads[0].state = THREAD_SEARCHING;
+ for (i = 1; i < MAX_THREADS; i++)
+ threads[i].state = THREAD_AVAILABLE;
+
+ // Launch the helper threads
+ for (i = 1; i < MAX_THREADS; i++)
+ {
+
+#if !defined(_MSC_VER)
+ ok = (pthread_create(pthread, NULL, init_thread, (void*)(&i)) == 0);
+#else
+ ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, NULL) != NULL);
+#endif
+
+ if (!ok)
+ {
+ cout << "Failed to create thread number " << i << endl;
+ Application::exit_with_failure();
+ }
+
+ // Wait until the thread has finished launching and is gone to sleep
+ while (threads[i].state != THREAD_SLEEPING);
+ }
}
- // destroy_split_point_stack() is called when the program exits, and
- // destroys all locks in the precomputed split point objects.
+ // exit_threads() is called when the program exits. It makes all the
+ // helper threads exit cleanly.
+
+ void ThreadsManager::exit_threads() {
+
+ ActiveThreads = MAX_THREADS; // HACK
+ AllThreadsShouldSleep = true; // HACK
+ wake_sleeping_threads();
+
+ // This makes the threads to exit idle_loop()
+ AllThreadsShouldExit = true;
- void destroy_split_point_stack() {
+ // Wait for thread termination
+ for (int i = 1; i < MAX_THREADS; i++)
+ while (threads[i].state != THREAD_TERMINATED);
- for (int i = 0; i < THREAD_MAX; i++)
+ // Now we can safely destroy the locks
+ for (int i = 0; i < MAX_THREADS; i++)
for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
lock_destroy(&(SplitPointStack[i][j].lock));
+
+ lock_destroy(&WaitLock);
+ lock_destroy(&MPLock);
}
- // thread_should_stop() checks whether the thread with a given threadID has
- // been asked to stop, directly or indirectly. This can happen if a beta
- // cutoff has occurred in the thread's currently active split point, or in
- // some ancestor of the current split point.
+ // thread_should_stop() checks whether the thread should stop its search.
+ // This can happen if a beta cutoff has occurred in the thread's currently
+ // active split point, or in some ancestor of the current split point.
- bool thread_should_stop(int threadID) {
+ bool ThreadsManager::thread_should_stop(int threadID) const {
assert(threadID >= 0 && threadID < ActiveThreads);
SplitPoint* sp;
- if (Threads[threadID].stop)
- return true;
- if (ActiveThreads <= 2)
- return false;
- for (sp = Threads[threadID].splitPoint; sp != NULL; sp = sp->parent)
- if (sp->finished)
- {
- Threads[threadID].stop = true;
- return true;
- }
- return false;
+ for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent);
+ return sp != NULL;
}
// threads which are busy searching the split point at the top of "slave"'s
// split point stack (the "helpful master concept" in YBWC terminology).
- bool thread_is_available(int slave, int master) {
+ bool ThreadsManager::thread_is_available(int slave, int master) const {
assert(slave >= 0 && slave < ActiveThreads);
assert(master >= 0 && master < ActiveThreads);
assert(ActiveThreads > 1);
- if (!Threads[slave].idle || slave == master)
+ if (threads[slave].state != THREAD_AVAILABLE || slave == master)
return false;
// Make a local copy to be sure doesn't change under our feet
- int localActiveSplitPoints = Threads[slave].activeSplitPoints;
+ int localActiveSplitPoints = threads[slave].activeSplitPoints;
if (localActiveSplitPoints == 0)
// No active split points means that the thread is available as
return true;
// Apply the "helpful master" concept if possible. Use localActiveSplitPoints
- // that is known to be > 0, instead of Threads[slave].activeSplitPoints that
+ // that is known to be > 0, instead of threads[slave].activeSplitPoints that
// could have been set to 0 by another thread leading to an out of bound access.
if (SplitPointStack[slave][localActiveSplitPoints - 1].slaves[master])
return true;
}
- // idle_thread_exists() tries to find an idle thread which is available as
+ // available_thread_exists() tries to find an idle thread which is available as
// a slave for the thread with threadID "master".
- bool idle_thread_exists(int master) {
+ bool ThreadsManager::available_thread_exists(int master) const {
assert(master >= 0 && master < ActiveThreads);
assert(ActiveThreads > 1);
// threads have returned from sp_search_pv (or, equivalently, when
// splitPoint->cpus becomes 0), split() returns true.
- bool split(const Position& p, SearchStack* sstck, int ply,
- Value* alpha, Value* beta, Value* bestValue, const Value futilityValue,
- Depth depth, int* moves, MovePicker* mp, int master, bool pvNode) {
+ bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply,
+ Value* alpha, const Value beta, Value* bestValue,
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode) {
assert(p.is_ok());
assert(sstck != NULL);
assert(ply >= 0 && ply < PLY_MAX);
- assert(*bestValue >= -VALUE_INFINITE && *bestValue <= *alpha);
- assert(!pvNode || *alpha < *beta);
- assert(*beta <= VALUE_INFINITE);
+ assert(*bestValue >= -VALUE_INFINITE);
+ assert( ( pvNode && *bestValue <= *alpha)
+ || (!pvNode && *bestValue < beta ));
+ assert(!pvNode || *alpha < beta);
+ assert(beta <= VALUE_INFINITE);
assert(depth > Depth(0));
assert(master >= 0 && master < ActiveThreads);
assert(ActiveThreads > 1);
// If no other thread is available to help us, or if we have too many
// active split points, don't split.
- if ( !idle_thread_exists(master)
- || Threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX)
+ if ( !available_thread_exists(master)
+ || threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX)
{
lock_release(&MPLock);
return false;
}
// Pick the next available split point object from the split point stack
- splitPoint = SplitPointStack[master] + Threads[master].activeSplitPoints;
- Threads[master].activeSplitPoints++;
+ splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints];
// Initialize the split point object
- splitPoint->parent = Threads[master].splitPoint;
- splitPoint->finished = false;
+ splitPoint->parent = threads[master].splitPoint;
+ splitPoint->stopRequest = false;
splitPoint->ply = ply;
splitPoint->depth = depth;
- splitPoint->alpha = pvNode ? *alpha : (*beta - 1);
- splitPoint->beta = *beta;
+ splitPoint->mateThreat = mateThreat;
+ splitPoint->alpha = pvNode ? *alpha : beta - 1;
+ splitPoint->beta = beta;
splitPoint->pvNode = pvNode;
splitPoint->bestValue = *bestValue;
- splitPoint->futilityValue = futilityValue;
splitPoint->master = master;
splitPoint->mp = mp;
splitPoint->moves = *moves;
for (int i = 0; i < ActiveThreads; i++)
splitPoint->slaves[i] = 0;
- Threads[master].idle = false;
- Threads[master].stop = false;
- Threads[master].splitPoint = splitPoint;
+ threads[master].splitPoint = splitPoint;
+ threads[master].activeSplitPoints++;
- // Allocate available threads setting idle flag to false
+ // If we are here it means we are not available
+ assert(threads[master].state != THREAD_AVAILABLE);
+
+ // Allocate available threads setting state to THREAD_BOOKED
for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++)
if (thread_is_available(i, master))
{
- Threads[i].idle = false;
- Threads[i].stop = false;
- Threads[i].splitPoint = splitPoint;
+ threads[i].state = THREAD_BOOKED;
+ threads[i].splitPoint = splitPoint;
splitPoint->slaves[i] = 1;
splitPoint->cpus++;
}
assert(splitPoint->cpus > 1);
- // We can release the lock because master and slave threads are already booked
+ // We can release the lock because slave threads are already booked and master is not available
lock_release(&MPLock);
// Tell the threads that they have work to do. This will make them leave
for (int i = 0; i < ActiveThreads; i++)
if (i == master || splitPoint->slaves[i])
{
- memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 3 * sizeof(SearchStack));
- Threads[i].workIsWaiting = true; // This makes the slave to exit from idle_loop()
+ memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 4 * sizeof(SearchStack));
+
+ assert(i == master || threads[i].state == THREAD_BOOKED);
+
+ threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop()
}
// Everything is set up. The master thread enters the idle loop, from
- // which it will instantly launch a search, because its workIsWaiting
- // slot is 'true'. We send the split point as a second parameter to the
+ // which it will instantly launch a search, because its state is
+ // THREAD_WORKISWAITING. We send the split point as a second parameter to the
// idle loop, which means that the main thread will return from the idle
// loop when all threads have finished their work at this split point
// (i.e. when splitPoint->cpus == 0).
if (pvNode)
*alpha = splitPoint->alpha;
- *beta = splitPoint->beta;
*bestValue = splitPoint->bestValue;
- Threads[master].stop = false;
- Threads[master].idle = false;
- Threads[master].activeSplitPoints--;
- Threads[master].splitPoint = splitPoint->parent;
+ threads[master].activeSplitPoints--;
+ threads[master].splitPoint = splitPoint->parent;
lock_release(&MPLock);
return true;
// wake_sleeping_threads() wakes up all sleeping threads when it is time
// to start a new search from the root.
- void wake_sleeping_threads() {
+ void ThreadsManager::wake_sleeping_threads() {
- if (ActiveThreads > 1)
- {
- for (int i = 1; i < ActiveThreads; i++)
- {
- Threads[i].idle = true;
- Threads[i].workIsWaiting = false;
- }
+ assert(AllThreadsShouldSleep);
+ assert(ActiveThreads > 0);
+
+ AllThreadsShouldSleep = false;
+
+ if (ActiveThreads == 1)
+ return;
#if !defined(_MSC_VER)
- pthread_mutex_lock(&WaitLock);
- pthread_cond_broadcast(&WaitCond);
- pthread_mutex_unlock(&WaitLock);
+ pthread_mutex_lock(&WaitLock);
+ pthread_cond_broadcast(&WaitCond);
+ pthread_mutex_unlock(&WaitLock);
#else
- for (int i = 1; i < THREAD_MAX; i++)
- SetEvent(SitIdleEvent[i]);
+ for (int i = 1; i < MAX_THREADS; i++)
+ SetEvent(SitIdleEvent[i]);
#endif
+
+ }
+
+
+ // put_threads_to_sleep() makes all the threads go to sleep just before
+ // to leave think(), at the end of the search. Threads should have already
+ // finished the job and should be idle.
+
+ void ThreadsManager::put_threads_to_sleep() {
+
+ assert(!AllThreadsShouldSleep);
+
+ // This makes the threads to go to sleep
+ AllThreadsShouldSleep = true;
+ }
+
+ /// The RootMoveList class
+
+ // RootMoveList c'tor
+
+ RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) {
+
+ SearchStack ss[PLY_MAX_PLUS_2];
+ MoveStack mlist[MaxRootMoves];
+ StateInfo st;
+ bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
+
+ // Generate all legal moves
+ MoveStack* last = generate_moves(pos, mlist);
+
+ // Add each move to the moves[] array
+ for (MoveStack* cur = mlist; cur != last; cur++)
+ {
+ bool includeMove = includeAllMoves;
+
+ for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
+ includeMove = (searchMoves[k] == cur->move);
+
+ if (!includeMove)
+ continue;
+
+ // Find a quick score for the move
+ init_ss_array(ss);
+ pos.do_move(cur->move, st);
+ moves[count].move = cur->move;
+ moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
+ moves[count].pv[0] = cur->move;
+ moves[count].pv[1] = MOVE_NONE;
+ pos.undo_move(cur->move);
+ count++;
}
+ sort();
}
- // init_thread() is the function which is called when a new thread is
- // launched. It simply calls the idle_loop() function with the supplied
- // threadID. There are two versions of this function; one for POSIX
- // threads and one for Windows threads.
+ // RootMoveList simple methods definitions
-#if !defined(_MSC_VER)
+ void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) {
- void* init_thread(void *threadID) {
+ moves[moveNum].nodes = nodes;
+ moves[moveNum].cumulativeNodes += nodes;
+ }
- idle_loop(*(int*)threadID, NULL);
- return NULL;
+ void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
+
+ moves[moveNum].ourBeta = our;
+ moves[moveNum].theirBeta = their;
}
-#else
+ void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
- DWORD WINAPI init_thread(LPVOID threadID) {
+ int j;
- idle_loop(*(int*)threadID, NULL);
- return NULL;
+ for (j = 0; pv[j] != MOVE_NONE; j++)
+ moves[moveNum].pv[j] = pv[j];
+
+ moves[moveNum].pv[j] = MOVE_NONE;
}
-#endif
-}
+ // RootMoveList::sort() sorts the root move list at the beginning of a new
+ // iteration.
+
+ void RootMoveList::sort() {
+
+ sort_multipv(count - 1); // Sort all items
+ }
+
+
+ // RootMoveList::sort_multipv() sorts the first few moves in the root move
+ // list by their scores and depths. It is used to order the different PVs
+ // correctly in MultiPV mode.
+
+ void RootMoveList::sort_multipv(int n) {
+
+ int i,j;
+
+ for (i = 1; i <= n; i++)
+ {
+ RootMove rm = moves[i];
+ for (j = i; j > 0 && moves[j - 1] < rm; j--)
+ moves[j] = moves[j - 1];
+
+ moves[j] = rm;
+ }
+ }
+
+} // namspace
projects / stockfish / blobdiff