#include "../search.h"
#include "../thread_win32.h"
#include "../types.h"
+#include "../uci.h"
#include "tbprobe.h"
namespace {
-constexpr int TBPIECES = 6; // Max number of supported pieces
+constexpr int TBPIECES = 7; // Max number of supported pieces
enum { BigEndian, LittleEndian };
enum TBType { KEY, WDL, DTZ }; // Used as template parameter
// Each table has a set of flags: all of them refer to DTZ tables, the last one to WDL tables
-enum TBFlag { STM = 1, Mapped = 2, WinPlies = 4, LossPlies = 8, SingleValue = 128 };
+enum TBFlag { STM = 1, Mapped = 2, WinPlies = 4, LossPlies = 8, Wide = 16, SingleValue = 128 };
inline WDLScore operator-(WDLScore d) { return WDLScore(-int(d)); }
inline Square operator^=(Square& s, int i) { return s = Square(int(s) ^ i); }
int MapKK[10][SQUARE_NB]; // [MapA1D1D4][SQUARE_NB]
int Binomial[6][SQUARE_NB]; // [k][n] k elements from a set of n elements
-int LeadPawnIdx[5][SQUARE_NB]; // [leadPawnsCnt][SQUARE_NB]
-int LeadPawnsSize[5][4]; // [leadPawnsCnt][FILE_A..FILE_D]
+int LeadPawnIdx[6][SQUARE_NB]; // [leadPawnsCnt][SQUARE_NB]
+int LeadPawnsSize[6][4]; // [leadPawnsCnt][FILE_A..FILE_D]
// Comparison function to sort leading pawns in ascending MapPawns[] order
bool pawns_comp(Square i, Square j) { return MapPawns[i] < MapPawns[j]; }
typedef uint16_t Sym; // Huffman symbol
struct LR {
- enum Side { Left, Right, Value };
+ enum Side { Left, Right };
uint8_t lr[3]; // The first 12 bits is the left-hand symbol, the second 12
// bits is the right-hand symbol. If symbol has length 1,
- // then the first byte is the stored value.
+ // then the left-hand symbol is the stored value.
template<Side S>
Sym get() {
return S == Left ? ((lr[1] & 0xF) << 8) | lr[0] :
- S == Right ? (lr[2] << 4) | (lr[1] >> 4) :
- S == Value ? lr[0] : (assert(false), Sym(-1));
+ S == Right ? (lr[2] << 4) | (lr[1] >> 4) : (assert(false), Sym(-1));
}
};
typedef std::tuple<Key, TBTable<WDL>*, TBTable<DTZ>*> Entry;
- static const int Size = 1 << 12; // 4K table, indexed by key's 12 lsb
+ static constexpr int Size = 1 << 12; // 4K table, indexed by key's 12 lsb
+ static constexpr int Overflow = 1; // Number of elements allowed to map to the last bucket
- Entry hashTable[Size];
+ Entry hashTable[Size + Overflow];
std::deque<TBTable<WDL>> wdlTable;
std::deque<TBTable<DTZ>> dtzTable;
void insert(Key key, TBTable<WDL>* wdl, TBTable<DTZ>* dtz) {
- Entry* entry = &hashTable[(uint32_t)key & (Size - 1)];
+ uint32_t homeBucket = (uint32_t)key & (Size - 1);
+ Entry entry = std::make_tuple(key, wdl, dtz);
// Ensure last element is empty to avoid overflow when looking up
- for ( ; entry - hashTable < Size - 1; ++entry)
- if (std::get<KEY>(*entry) == key || !std::get<WDL>(*entry)) {
- *entry = std::make_tuple(key, wdl, dtz);
+ for (uint32_t bucket = homeBucket; bucket < Size + Overflow - 1; ++bucket) {
+ Key otherKey = std::get<KEY>(hashTable[bucket]);
+ if (otherKey == key || !std::get<WDL>(hashTable[bucket])) {
+ hashTable[bucket] = entry;
return;
}
+
+ // Robin Hood hashing: If we've probed for longer than this element,
+ // insert here and search for a new spot for the other element instead.
+ uint32_t otherHomeBucket = (uint32_t)otherKey & (Size - 1);
+ if (otherHomeBucket > homeBucket) {
+ swap(entry, hashTable[bucket]);
+ key = otherKey;
+ homeBucket = otherHomeBucket;
+ }
+ }
std::cerr << "TB hash table size too low!" << std::endl;
exit(1);
}
offset -= d->blockLength[block++] + 1;
// Finally, we find the start address of our block of canonical Huffman symbols
- uint32_t* ptr = (uint32_t*)(d->data + block * d->sizeofBlock);
+ uint32_t* ptr = (uint32_t*)(d->data + ((uint64_t)block * d->sizeofBlock));
// Read the first 64 bits in our block, this is a (truncated) sequence of
// unknown number of symbols of unknown length but we know the first one
}
}
- return d->btree[sym].get<LR::Value>();
+ return d->btree[sym].get<LR::Left>();
}
bool check_dtz_stm(TBTable<WDL>*, int, File) { return true; }
uint8_t* map = entry->map;
uint16_t* idx = entry->get(0, f)->map_idx;
- if (flags & TBFlag::Mapped)
- value = map[idx[WDLMap[wdl + 2]] + value];
+ if (flags & TBFlag::Mapped) {
+ if (flags & TBFlag::Wide)
+ value = ((uint16_t *)map)[idx[WDLMap[wdl + 2]] + value];
+ else
+ value = map[idx[WDLMap[wdl + 2]] + value];
+ }
// DTZ tables store distance to zero in number of moves or plies. We
// want to return plies, so we have convert to plies when needed.
d->symlen.resize(number<uint16_t, LittleEndian>(data)); data += sizeof(uint16_t);
d->btree = (LR*)data;
- // The comrpession scheme used is "Recursive Pairing", that replaces the most
+ // The compression scheme used is "Recursive Pairing", that replaces the most
// frequent adjacent pair of symbols in the source message by a new symbol,
// reevaluating the frequencies of all of the symbol pairs with respect to
// the extended alphabet, and then repeating the process.
e.map = data;
for (File f = FILE_A; f <= maxFile; ++f) {
- if (e.get(0, f)->flags & TBFlag::Mapped)
- for (int i = 0; i < 4; ++i) { // Sequence like 3,x,x,x,1,x,0,2,x,x
- e.get(0, f)->map_idx[i] = (uint16_t)(data - e.map + 1);
- data += *data + 1;
+ auto flags = e.get(0, f)->flags;
+ if (flags & TBFlag::Mapped) {
+ if (flags & TBFlag::Wide) {
+ data += (uintptr_t)data & 1; // Word alignment, we may have a mixed table
+ for (int i = 0; i < 4; ++i) { // Sequence like 3,x,x,x,1,x,0,2,x,x
+ e.get(0, f)->map_idx[i] = (uint16_t)((uint16_t *)data - (uint16_t *)e.map + 1);
+ data += 2 * number<uint16_t, LittleEndian>(data) + 2;
+ }
}
+ else {
+ for (int i = 0; i < 4; ++i) {
+ e.get(0, f)->map_idx[i] = (uint16_t)(data - e.map + 1);
+ data += *data + 1;
+ }
+ }
+ }
}
return data += (uintptr_t)data & 1; // Word alignment
// All of this means that during probing, the engine must look at captures and probe
// their results and must probe the position itself. The "best" result of these
// probes is the correct result for the position.
-// DTZ table don't store values when a following move is a zeroing winning move
+// DTZ tables do not store values when a following move is a zeroing winning move
// (winning capture or winning pawn move). Also DTZ store wrong values for positions
// where the best move is an ep-move (even if losing). So in all these cases set
// the state to ZEROING_BEST_MOVE.
-template<bool CheckZeroingMoves = false>
+template<bool CheckZeroingMoves>
WDLScore search(Position& pos, ProbeState* result) {
WDLScore value, bestValue = WDLLoss;
moveCount++;
pos.do_move(move, st);
- value = -search(pos, result);
+ value = -search<false>(pos, result);
pos.undo_move(move);
if (*result == FAIL)
// among pawns with same file, the one with lowest rank.
int availableSquares = 47; // Available squares when lead pawn is in a2
- // Init the tables for the encoding of leading pawns group: with 6-men TB we
- // can have up to 4 leading pawns (KPPPPK).
- for (int leadPawnsCnt = 1; leadPawnsCnt <= 4; ++leadPawnsCnt)
+ // Init the tables for the encoding of leading pawns group: with 7-men TB we
+ // can have up to 5 leading pawns (KPPPPPK).
+ for (int leadPawnsCnt = 1; leadPawnsCnt <= 5; ++leadPawnsCnt)
for (File f = FILE_A; f <= FILE_D; ++f)
{
// Restart the index at every file because TB table is splitted
for (PieceType p3 = PAWN; p3 <= p2; ++p3) {
TBTables.add({KING, p1, p2, p3, KING});
- for (PieceType p4 = PAWN; p4 <= p3; ++p4)
+ for (PieceType p4 = PAWN; p4 <= p3; ++p4) {
TBTables.add({KING, p1, p2, p3, p4, KING});
- for (PieceType p4 = PAWN; p4 < KING; ++p4)
+ for (PieceType p5 = PAWN; p5 <= p4; ++p5)
+ TBTables.add({KING, p1, p2, p3, p4, p5, KING});
+
+ for (PieceType p5 = PAWN; p5 < KING; ++p5)
+ TBTables.add({KING, p1, p2, p3, p4, KING, p5});
+ }
+
+ for (PieceType p4 = PAWN; p4 < KING; ++p4) {
TBTables.add({KING, p1, p2, p3, KING, p4});
+
+ for (PieceType p5 = PAWN; p5 <= p4; ++p5)
+ TBTables.add({KING, p1, p2, p3, KING, p4, p5});
+ }
}
for (PieceType p3 = PAWN; p3 <= p1; ++p3)
WDLScore Tablebases::probe_wdl(Position& pos, ProbeState* result) {
*result = OK;
- return search(pos, result);
+ return search<false>(pos, result);
}
// Probe the DTZ table for a particular position.
// The return value is from the point of view of the side to move:
// n < -100 : loss, but draw under 50-move rule
// -100 <= n < -1 : loss in n ply (assuming 50-move counter == 0)
+// -1 : loss, the side to move is mated
// 0 : draw
// 1 < n <= 100 : win in n ply (assuming 50-move counter == 0)
// 100 < n : win, but draw under 50-move rule
// otherwise we will get the dtz of the next move sequence. Search the
// position after the move to get the score sign (because even in a
// winning position we could make a losing capture or going for a draw).
- dtz = zeroing ? -dtz_before_zeroing(search(pos, result))
+ dtz = zeroing ? -dtz_before_zeroing(search<false>(pos, result))
: -probe_dtz(pos, result);
- pos.undo_move(move);
-
- if (*result == FAIL)
- return 0;
+ // If the move mates, force minDTZ to 1
+ if (dtz == 1 && pos.checkers() && MoveList<LEGAL>(pos).size() == 0)
+ minDTZ = 1;
// Convert result from 1-ply search. Zeroing moves are already accounted
// by dtz_before_zeroing() that returns the DTZ of the previous move.
// Skip the draws and if we are winning only pick positive dtz
if (dtz < minDTZ && sign_of(dtz) == sign_of(wdl))
minDTZ = dtz;
- }
- // Special handle a mate position, when there are no legal moves, in this
- // case return value is somewhat arbitrary, so stick to the original TB code
- // that returns -1 in this case.
- return minDTZ == 0xFFFF ? -1 : minDTZ;
-}
-
-// Check whether there has been at least one repetition of positions
-// since the last capture or pawn move.
-static int has_repeated(StateInfo *st)
-{
- while (1) {
- int i = 4, e = std::min(st->rule50, st->pliesFromNull);
+ pos.undo_move(move);
- if (e < i)
+ if (*result == FAIL)
return 0;
-
- StateInfo *stp = st->previous->previous;
-
- do {
- stp = stp->previous->previous;
-
- if (stp->key == st->key)
- return 1;
-
- i += 2;
- } while (i <= e);
-
- st = st->previous;
}
+
+ // When there are no legal moves, the position is mate: we return -1
+ return minDTZ == 0xFFFF ? -1 : minDTZ;
}
-// Use the DTZ tables to filter out moves that don't preserve the win or draw.
-// If the position is lost, but DTZ is fairly high, only keep moves that
-// maximise DTZ.
+
+// Use the DTZ tables to rank root moves.
//
-// A return value false indicates that not all probes were successful and that
-// no moves were filtered out.
-bool Tablebases::root_probe(Position& pos, Search::RootMoves& rootMoves, Value& score)
-{
- assert(rootMoves.size());
+// A return value false indicates that not all probes were successful.
+bool Tablebases::root_probe(Position& pos, Search::RootMoves& rootMoves) {
ProbeState result;
- int dtz = probe_dtz(pos, &result);
-
- if (result == FAIL)
- return false;
-
StateInfo st;
- // Probe each move
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- Move move = rootMoves[i].pv[0];
- pos.do_move(move, st);
- int v = 0;
-
- if (pos.checkers() && dtz > 0) {
- ExtMove s[MAX_MOVES];
-
- if (generate<LEGAL>(pos, s) == s)
- v = 1;
- }
-
- if (!v) {
- if (st.rule50 != 0) {
- v = -probe_dtz(pos, &result);
-
- if (v > 0)
- ++v;
- else if (v < 0)
- --v;
- } else {
- v = -probe_wdl(pos, &result);
- v = dtz_before_zeroing(WDLScore(v));
- }
- }
-
- pos.undo_move(move);
-
- if (result == FAIL)
- return false;
-
- rootMoves[i].score = (Value)v;
- }
-
- // Obtain 50-move counter for the root position.
- // In Stockfish there seems to be no clean way, so we do it like this:
- int cnt50 = st.previous ? st.previous->rule50 : 0;
-
- // Use 50-move counter to determine whether the root position is
- // won, lost or drawn.
- WDLScore wdl = WDLDraw;
+ // Obtain 50-move counter for the root position
+ int cnt50 = pos.rule50_count();
- if (dtz > 0)
- wdl = (dtz + cnt50 <= 100) ? WDLWin : WDLCursedWin;
- else if (dtz < 0)
- wdl = (-dtz + cnt50 <= 100) ? WDLLoss : WDLBlessedLoss;
+ // Check whether a position was repeated since the last zeroing move.
+ bool rep = pos.has_repeated();
- // Determine the score to report to the user.
- score = WDL_to_value[wdl + 2];
+ int dtz, bound = Options["Syzygy50MoveRule"] ? 900 : 1;
- // If the position is winning or losing, but too few moves left, adjust the
- // score to show how close it is to winning or losing.
- // NOTE: int(PawnValueEg) is used as scaling factor in score_to_uci().
- if (wdl == WDLCursedWin && dtz <= 100)
- score = (Value)(((200 - dtz - cnt50) * int(PawnValueEg)) / 200);
- else if (wdl == WDLBlessedLoss && dtz >= -100)
- score = -(Value)(((200 + dtz - cnt50) * int(PawnValueEg)) / 200);
-
- // Now be a bit smart about filtering out moves.
- size_t j = 0;
-
- if (dtz > 0) { // winning (or 50-move rule draw)
- int best = 0xffff;
-
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- int v = rootMoves[i].score;
+ // Probe and rank each move
+ for (auto& m : rootMoves)
+ {
+ pos.do_move(m.pv[0], st);
- if (v > 0 && v < best)
- best = v;
+ // Calculate dtz for the current move counting from the root position
+ if (pos.rule50_count() == 0)
+ {
+ // In case of a zeroing move, dtz is one of -101/-1/0/1/101
+ WDLScore wdl = -probe_wdl(pos, &result);
+ dtz = dtz_before_zeroing(wdl);
}
-
- int max = best;
-
- // If the current phase has not seen repetitions, then try all moves
- // that stay safely within the 50-move budget, if there are any.
- if (!has_repeated(st.previous) && best + cnt50 <= 99)
- max = 99 - cnt50;
-
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- int v = rootMoves[i].score;
-
- if (v > 0 && v <= max)
- rootMoves[j++] = rootMoves[i];
+ else
+ {
+ // Otherwise, take dtz for the new position and correct by 1 ply
+ dtz = -probe_dtz(pos, &result);
+ dtz = dtz > 0 ? dtz + 1
+ : dtz < 0 ? dtz - 1 : dtz;
}
- } else if (dtz < 0) { // losing (or 50-move rule draw)
- int best = 0;
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- int v = rootMoves[i].score;
+ // Make sure that a mating move is assigned a dtz value of 1
+ if ( pos.checkers()
+ && dtz == 2
+ && MoveList<LEGAL>(pos).size() == 0)
+ dtz = 1;
- if (v < best)
- best = v;
- }
+ pos.undo_move(m.pv[0]);
- // Try all moves, unless we approach or have a 50-move rule draw.
- if (-best * 2 + cnt50 < 100)
- return true;
+ if (result == FAIL)
+ return false;
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- if (rootMoves[i].score == best)
- rootMoves[j++] = rootMoves[i];
- }
- } else { // drawing
- // Try all moves that preserve the draw.
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- if (rootMoves[i].score == 0)
- rootMoves[j++] = rootMoves[i];
- }
+ // Better moves are ranked higher. Certain wins are ranked equally.
+ // Losing moves are ranked equally unless a 50-move draw is in sight.
+ int r = dtz > 0 ? (dtz + cnt50 <= 99 && !rep ? 1000 : 1000 - (dtz + cnt50))
+ : dtz < 0 ? (-dtz * 2 + cnt50 < 100 ? -1000 : -1000 + (-dtz + cnt50))
+ : 0;
+ m.tbRank = r;
+
+ // Determine the score to be displayed for this move. Assign at least
+ // 1 cp to cursed wins and let it grow to 49 cp as the positions gets
+ // closer to a real win.
+ m.tbScore = r >= bound ? VALUE_MATE - MAX_PLY - 1
+ : r > 0 ? Value((std::max( 3, r - 800) * int(PawnValueEg)) / 200)
+ : r == 0 ? VALUE_DRAW
+ : r > -bound ? Value((std::min(-3, r + 800) * int(PawnValueEg)) / 200)
+ : -VALUE_MATE + MAX_PLY + 1;
}
- rootMoves.resize(j, Search::RootMove(MOVE_NONE));
-
return true;
}
-// Use the WDL tables to filter out moves that don't preserve the win or draw.
+
+// Use the WDL tables to rank root moves.
// This is a fallback for the case that some or all DTZ tables are missing.
//
-// A return value false indicates that not all probes were successful and that
-// no moves were filtered out.
-bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves, Value& score)
-{
- ProbeState result;
+// A return value false indicates that not all probes were successful.
+bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves) {
- WDLScore wdl = Tablebases::probe_wdl(pos, &result);
+ static const int WDL_to_rank[] = { -1000, -899, 0, 899, 1000 };
- if (result == FAIL)
- return false;
+ ProbeState result;
+ StateInfo st;
- score = WDL_to_value[wdl + 2];
+ bool rule50 = Options["Syzygy50MoveRule"];
- StateInfo st;
+ // Probe and rank each move
+ for (auto& m : rootMoves)
+ {
+ pos.do_move(m.pv[0], st);
- int best = WDLLoss;
+ WDLScore wdl = -probe_wdl(pos, &result);
- // Probe each move
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- Move move = rootMoves[i].pv[0];
- pos.do_move(move, st);
- WDLScore v = -Tablebases::probe_wdl(pos, &result);
- pos.undo_move(move);
+ pos.undo_move(m.pv[0]);
if (result == FAIL)
return false;
- rootMoves[i].score = (Value)v;
+ m.tbRank = WDL_to_rank[wdl + 2];
- if (v > best)
- best = v;
+ if (!rule50)
+ wdl = wdl > WDLDraw ? WDLWin
+ : wdl < WDLDraw ? WDLLoss : WDLDraw;
+ m.tbScore = WDL_to_value[wdl + 2];
}
- size_t j = 0;
-
- for (size_t i = 0; i < rootMoves.size(); ++i) {
- if (rootMoves[i].score == best)
- rootMoves[j++] = rootMoves[i];
- }
-
- rootMoves.resize(j, Search::RootMove(MOVE_NONE));
-
return true;
}
projects / stockfish / blobdiff