X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=20ac1608e2fee1eb0e1338c3dbbe940275cc9f36;hp=fc0bdfb47c1c96f1738c8403795640fbf13056f8;hb=6849f0800e82845271ad5888600c141857e744ec;hpb=47ee6d9fa4091aa05f6fedb62a2bb652b0422f08 diff --git a/src/tt.cpp b/src/tt.cpp index fc0bdfb4..20ac1608 100644 --- a/src/tt.cpp +++ b/src/tt.cpp @@ -23,10 +23,9 @@ //// #include -#include #include +#include -#include "movegen.h" #include "tt.h" // The main transposition table @@ -38,7 +37,7 @@ TranspositionTable TT; TranspositionTable::TranspositionTable() { - size = writes = 0; + size = 0; entries = 0; generation = 0; } @@ -56,21 +55,23 @@ void TranspositionTable::set_size(size_t mbSize) { size_t newSize = 1024; - // We store a cluster of ClusterSize number of TTEntry for each position - // and newSize is the maximum number of storable positions. - while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20)) + // Transposition table consists of clusters and each cluster consists + // of ClusterSize number of TTEntries. Each non-empty entry contains + // information of exactly one position and newSize is the number of + // clusters we are going to allocate. + while (2ULL * newSize * sizeof(TTCluster) <= (mbSize << 20)) newSize *= 2; if (newSize != size) { size = newSize; delete [] entries; - entries = new TTCluster[size]; + entries = new (std::nothrow) TTCluster[size]; if (!entries) { std::cerr << "Failed to allocate " << mbSize << " MB for transposition table." << std::endl; - Application::exit_with_failure(); + exit(EXIT_FAILURE); } clear(); } @@ -80,7 +81,7 @@ void TranspositionTable::set_size(size_t mbSize) { /// TranspositionTable::clear overwrites the entire transposition table /// with zeroes. It is called whenever the table is resized, or when the /// user asks the program to clear the table (from the UCI interface). -/// Perhaps we should also clear it when the "ucinewgame" command is recieved? +/// Perhaps we should also clear it when the "ucinewgame" command is received? void TranspositionTable::clear() { @@ -88,18 +89,19 @@ void TranspositionTable::clear() { } -/// TranspositionTable::store writes a new entry containing a position, -/// a value, a value type, a search depth, and a best move to the -/// transposition table. Transposition table is organized in clusters of -/// four TTEntry objects, and when a new entry is written, it replaces -/// the least valuable of the four entries in a cluster. A TTEntry t1 is -/// considered to be more valuable than a TTEntry t2 if t1 is from the +/// TranspositionTable::store writes a new entry containing position key and +/// valuable information of current position. +/// The Lowest order bits of position key are used to decide on which cluster +/// the position will be placed. +/// When a new entry is written and there are no empty entries available in cluster, +/// it replaces the least valuable of entries. +/// A TTEntry t1 is considered to be more valuable than a TTEntry t2 if t1 is from the /// current search and t2 is from a previous search, or if the depth of t1 -/// is bigger than the depth of t2. A TTEntry of type VALUE_TYPE_EVAL -/// never replaces another entry for the same position. +/// is bigger than the depth of t2. void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m, Value statV, Value kingD) { + int c1, c2, c3; TTEntry *tte, *replace; uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key @@ -108,25 +110,25 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, { if (!tte->key() || tte->key() == posKey32) // empty or overwrite old { - // Preserve any exsisting ttMove + // Preserve any existing ttMove if (m == MOVE_NONE) m = tte->move(); tte->save(posKey32, v, t, d, m, generation, statV, kingD); return; } - else if (i == 0) // replace would be a no-op in this common case + + if (i == 0) // Replacing first entry is default and already set before entering for-loop continue; - int c1 = (replace->generation() == generation ? 2 : 0); - int c2 = (tte->generation() == generation ? -2 : 0); - int c3 = (tte->depth() < replace->depth() ? 1 : 0); + c1 = (replace->generation() == generation ? 2 : 0); + c2 = (tte->generation() == generation ? -2 : 0); + c3 = (tte->depth() < replace->depth() ? 1 : 0); if (c1 + c2 + c3 > 0) replace = tte; } replace->save(posKey32, v, t, d, m, generation, statV, kingD); - writes++; } @@ -153,69 +155,5 @@ TTEntry* TranspositionTable::retrieve(const Key posKey) const { /// entries from the current search. void TranspositionTable::new_search() { - generation++; - writes = 0; -} - - -/// TranspositionTable::insert_pv() is called at the end of a search -/// iteration, and inserts the PV back into the PV. This makes sure -/// the old PV moves are searched first, even if the old TT entries -/// have been overwritten. - -void TranspositionTable::insert_pv(const Position& pos, Move pv[]) { - - StateInfo st; - Position p(pos, pos.thread()); - - for (int i = 0; pv[i] != MOVE_NONE; i++) - { - TTEntry *tte = retrieve(p.get_key()); - if (!tte || tte->move() != pv[i]) - store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i], VALUE_NONE, VALUE_NONE); - p.do_move(pv[i], st); - } -} - - -/// TranspositionTable::extract_pv() extends a PV by adding moves from the -/// transposition table at the end. This should ensure that the PV is almost -/// always at least two plies long, which is important, because otherwise we -/// will often get single-move PVs when the search stops while failing high, -/// and a single-move PV means that we don't have a ponder move. - -void TranspositionTable::extract_pv(const Position& pos, Move pv[], const int PLY_MAX) { - - const TTEntry* tte; - StateInfo st; - Position p(pos, pos.thread()); - int ply = 0; - - // Update position to the end of current PV - while (pv[ply] != MOVE_NONE) - p.do_move(pv[ply++], st); - - // Try to add moves from TT while possible - while ( (tte = retrieve(p.get_key())) != NULL - && tte->move() != MOVE_NONE - && move_is_legal(p, tte->move()) - && (!p.is_draw() || ply < 2) - && ply < PLY_MAX) - { - pv[ply] = tte->move(); - p.do_move(pv[ply++], st); - } - pv[ply] = MOVE_NONE; -} - - -/// TranspositionTable::full() returns the permill of all transposition table -/// entries which have received at least one write during the current search. -/// It is used to display the "info hashfull ..." information in UCI. - -int TranspositionTable::full() const { - - double N = double(size) * ClusterSize; - return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N)))); }