/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (c) 2013 Ronald de Man
- Copyright (C) 2016-2018 Marco Costalba, Lucas Braesch
+ Copyright (C) 2016-2019 Marco Costalba, Lucas Braesch
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <algorithm>
#include <atomic>
#include <cstdint>
-#include <cstring> // For std::memset
+#include <cstring> // For std::memset and std::memcpy
#include <deque>
#include <fstream>
#include <iostream>
#include "../movegen.h"
#include "../position.h"
#include "../search.h"
-#include "../thread_win32.h"
+#include "../thread_win32_osx.h"
#include "../types.h"
+#include "../uci.h"
#include "tbprobe.h"
namespace {
+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); }
inline Square operator^(Square s, int i) { return Square(int(s) ^ i); }
-// DTZ tables don't store valid scores for moves that reset the rule50 counter
-// like captures and pawn moves but we can easily recover the correct dtz of the
-// previous move if we know the position's WDL score.
-int dtz_before_zeroing(WDLScore wdl) {
- return wdl == WDLWin ? 1 :
- wdl == WDLCursedWin ? 101 :
- wdl == WDLBlessedLoss ? -101 :
- wdl == WDLLoss ? -1 : 0;
-}
-
-// Return the sign of a number (-1, 0, 1)
-template <typename T> int sign_of(T val) {
- return (T(0) < val) - (val < T(0));
-}
-
-// Numbers in little endian used by sparseIndex[] to point into blockLength[]
-struct SparseEntry {
- char block[4]; // Number of block
- char offset[2]; // Offset within the block
-};
-
-static_assert(sizeof(SparseEntry) == 6, "SparseEntry must be 6 bytes");
-
-typedef uint16_t Sym; // Huffman symbol
-
-struct LR {
- enum Side { Left, Right, Value };
-
- 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.
- 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));
- }
-};
-
-static_assert(sizeof(LR) == 3, "LR tree entry must be 3 bytes");
-
-constexpr int TBPIECES = 6;
-
-struct PairsData {
- int flags;
- size_t sizeofBlock; // Block size in bytes
- size_t span; // About every span values there is a SparseIndex[] entry
- int blocksNum; // Number of blocks in the TB file
- int maxSymLen; // Maximum length in bits of the Huffman symbols
- int minSymLen; // Minimum length in bits of the Huffman symbols
- Sym* lowestSym; // lowestSym[l] is the symbol of length l with the lowest value
- LR* btree; // btree[sym] stores the left and right symbols that expand sym
- uint16_t* blockLength; // Number of stored positions (minus one) for each block: 1..65536
- int blockLengthSize; // Size of blockLength[] table: padded so it's bigger than blocksNum
- SparseEntry* sparseIndex; // Partial indices into blockLength[]
- size_t sparseIndexSize; // Size of SparseIndex[] table
- uint8_t* data; // Start of Huffman compressed data
- std::vector<uint64_t> base64; // base64[l - min_sym_len] is the 64bit-padded lowest symbol of length l
- std::vector<uint8_t> symlen; // Number of values (-1) represented by a given Huffman symbol: 1..256
- Piece pieces[TBPIECES]; // Position pieces: the order of pieces defines the groups
- uint64_t groupIdx[TBPIECES+1]; // Start index used for the encoding of the group's pieces
- int groupLen[TBPIECES+1]; // Number of pieces in a given group: KRKN -> (3, 1)
-};
-
-// Helper struct to avoid manually defining entry copy constructor as we
-// should because the default one is not compatible with std::atomic_bool.
-struct Atomic {
- Atomic() = default;
- Atomic(const Atomic& e) { ready = e.ready.load(); } // MSVC 2013 wants assignment within body
- std::atomic_bool ready;
-};
-
-// We define types for the different parts of the WDLEntry and DTZEntry with
-// corresponding specializations for pieces or pawns.
-
-struct WDLEntryPiece {
- PairsData* precomp;
-};
-
-struct WDLEntryPawn {
- uint8_t pawnCount[2]; // [Lead color / other color]
- WDLEntryPiece file[2][4]; // [wtm / btm][FILE_A..FILE_D]
-};
-
-struct DTZEntryPiece {
- PairsData* precomp;
- uint16_t map_idx[4]; // WDLWin, WDLLoss, WDLCursedWin, WDLBlessedLoss
- uint8_t* map;
-};
-
-struct DTZEntryPawn {
- uint8_t pawnCount[2];
- DTZEntryPiece file[4];
- uint8_t* map;
-};
-
-struct TBEntry : public Atomic {
- void* baseAddress;
- uint64_t mapping;
- Key key;
- Key key2;
- int pieceCount;
- bool hasPawns;
- bool hasUniquePieces;
-};
-
-// Now the main types: WDLEntry and DTZEntry
-struct WDLEntry : public TBEntry {
- WDLEntry(const std::string& code);
- ~WDLEntry();
- union {
- WDLEntryPiece pieceTable[2]; // [wtm / btm]
- WDLEntryPawn pawnTable;
- };
-};
-
-struct DTZEntry : public TBEntry {
- DTZEntry(const WDLEntry& wdl);
- ~DTZEntry();
- union {
- DTZEntryPiece pieceTable;
- DTZEntryPawn pawnTable;
- };
-};
-
-typedef decltype(WDLEntry::pieceTable) WDLPieceTable;
-typedef decltype(DTZEntry::pieceTable) DTZPieceTable;
-typedef decltype(WDLEntry::pawnTable ) WDLPawnTable;
-typedef decltype(DTZEntry::pawnTable ) DTZPawnTable;
-
-auto item(WDLPieceTable& e, int stm, int ) -> decltype(e[stm])& { return e[stm]; }
-auto item(DTZPieceTable& e, int , int ) -> decltype(e)& { return e; }
-auto item(WDLPawnTable& e, int stm, int f) -> decltype(e.file[stm][f])& { return e.file[stm][f]; }
-auto item(DTZPawnTable& e, int , int f) -> decltype(e.file[f])& { return e.file[f]; }
-
-template<typename E> struct Ret { typedef int type; };
-template<> struct Ret<WDLEntry> { typedef WDLScore type; };
+const std::string PieceToChar = " PNBRQK pnbrqk";
int MapPawns[SQUARE_NB];
int MapB1H1H7[SQUARE_NB];
int MapA1D1D4[SQUARE_NB];
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[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]; }
int off_A1H8(Square sq) { return int(rank_of(sq)) - file_of(sq); }
VALUE_MATE - MAX_PLY - 1
};
-const std::string PieceToChar = " PNBRQK pnbrqk";
-
-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]
-
-enum { BigEndian, LittleEndian };
-
template<typename T, int Half = sizeof(T) / 2, int End = sizeof(T) - 1>
-inline void swap_byte(T& x)
+inline void swap_endian(T& x)
{
- char tmp, *c = (char*)&x;
+ static_assert(std::is_unsigned<T>::value, "Argument of swap_endian not unsigned");
+
+ uint8_t tmp, *c = (uint8_t*)&x;
for (int i = 0; i < Half; ++i)
tmp = c[i], c[i] = c[End - i], c[End - i] = tmp;
}
-template<> inline void swap_byte<uint8_t, 0, 0>(uint8_t&) {}
+template<> inline void swap_endian<uint8_t>(uint8_t&) {}
template<typename T, int LE> T number(void* addr)
{
- const union { uint32_t i; char c[4]; } Le = { 0x01020304 };
- const bool IsLittleEndian = (Le.c[0] == 4);
+ static const union { uint32_t i; char c[4]; } Le = { 0x01020304 };
+ static const bool IsLittleEndian = (Le.c[0] == 4);
T v;
v = *((T*)addr);
if (LE != IsLittleEndian)
- swap_byte(v);
+ swap_endian(v);
return v;
}
-class HashTable {
-
- typedef std::pair<WDLEntry*, DTZEntry*> EntryPair;
- typedef std::pair<Key, EntryPair> Entry;
+// DTZ tables don't store valid scores for moves that reset the rule50 counter
+// like captures and pawn moves but we can easily recover the correct dtz of the
+// previous move if we know the position's WDL score.
+int dtz_before_zeroing(WDLScore wdl) {
+ return wdl == WDLWin ? 1 :
+ wdl == WDLCursedWin ? 101 :
+ wdl == WDLBlessedLoss ? -101 :
+ wdl == WDLLoss ? -1 : 0;
+}
- static constexpr int TBHASHBITS = 10;
- static constexpr int HSHMAX = 5;
+// Return the sign of a number (-1, 0, 1)
+template <typename T> int sign_of(T val) {
+ return (T(0) < val) - (val < T(0));
+}
- Entry hashTable[1 << TBHASHBITS][HSHMAX];
+// Numbers in little endian used by sparseIndex[] to point into blockLength[]
+struct SparseEntry {
+ char block[4]; // Number of block
+ char offset[2]; // Offset within the block
+};
- std::deque<WDLEntry> wdlTable;
- std::deque<DTZEntry> dtzTable;
+static_assert(sizeof(SparseEntry) == 6, "SparseEntry must be 6 bytes");
- void insert(Key key, WDLEntry* wdl, DTZEntry* dtz) {
- Entry* entry = hashTable[key >> (64 - TBHASHBITS)];
+typedef uint16_t Sym; // Huffman symbol
- for (int i = 0; i < HSHMAX; ++i, ++entry)
- if (!entry->second.first || entry->first == key) {
- *entry = std::make_pair(key, std::make_pair(wdl, dtz));
- return;
- }
+struct LR {
+ enum Side { Left, Right };
- std::cerr << "HSHMAX too low!" << std::endl;
- exit(1);
+ 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 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) : (assert(false), Sym(-1));
}
-
-public:
- template<typename E, int I = std::is_same<E, WDLEntry>::value ? 0 : 1>
- E* get(Key key) {
- Entry* entry = hashTable[key >> (64 - TBHASHBITS)];
-
- for (int i = 0; i < HSHMAX; ++i, ++entry)
- if (entry->first == key)
- return std::get<I>(entry->second);
-
- return nullptr;
- }
-
- void clear() {
- std::memset(hashTable, 0, sizeof(hashTable));
- wdlTable.clear();
- dtzTable.clear();
- }
- size_t size() const { return wdlTable.size(); }
- void insert(const std::vector<PieceType>& pieces);
};
-HashTable EntryTable;
+static_assert(sizeof(LR) == 3, "LR tree entry must be 3 bytes");
+// Tablebases data layout is structured as following:
+//
+// TBFile: memory maps/unmaps the physical .rtbw and .rtbz files
+// TBTable: one object for each file with corresponding indexing information
+// TBTables: has ownership of TBTable objects, keeping a list and a hash
+
+// class TBFile memory maps/unmaps the single .rtbw and .rtbz files. Files are
+// memory mapped for best performance. Files are mapped at first access: at init
+// time only existence of the file is checked.
class TBFile : public std::ifstream {
std::string fname;
// Memory map the file and check it. File should be already open and will be
// closed after mapping.
- uint8_t* map(void** baseAddress, uint64_t* mapping, const uint8_t* TB_MAGIC) {
+ uint8_t* map(void** baseAddress, uint64_t* mapping, TBType type) {
assert(is_open());
return *baseAddress = nullptr, nullptr;
fstat(fd, &statbuf);
+
+ if (statbuf.st_size % 64 != 16)
+ {
+ std::cerr << "Corrupt tablebase file " << fname << std::endl;
+ exit(EXIT_FAILURE);
+ }
+
*mapping = statbuf.st_size;
*baseAddress = mmap(nullptr, statbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
+ madvise(*baseAddress, statbuf.st_size, MADV_RANDOM);
::close(fd);
- if (*baseAddress == MAP_FAILED) {
+ if (*baseAddress == MAP_FAILED)
+ {
std::cerr << "Could not mmap() " << fname << std::endl;
- exit(1);
+ exit(EXIT_FAILURE);
}
#else
+ // Note FILE_FLAG_RANDOM_ACCESS is only a hint to Windows and as such may get ignored.
HANDLE fd = CreateFile(fname.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr,
- OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
+ OPEN_EXISTING, FILE_FLAG_RANDOM_ACCESS, nullptr);
if (fd == INVALID_HANDLE_VALUE)
return *baseAddress = nullptr, nullptr;
DWORD size_high;
DWORD size_low = GetFileSize(fd, &size_high);
+
+ if (size_low % 64 != 16)
+ {
+ std::cerr << "Corrupt tablebase file " << fname << std::endl;
+ exit(EXIT_FAILURE);
+ }
+
HANDLE mmap = CreateFileMapping(fd, nullptr, PAGE_READONLY, size_high, size_low, nullptr);
CloseHandle(fd);
- if (!mmap) {
+ if (!mmap)
+ {
std::cerr << "CreateFileMapping() failed" << std::endl;
- exit(1);
+ exit(EXIT_FAILURE);
}
*mapping = (uint64_t)mmap;
*baseAddress = MapViewOfFile(mmap, FILE_MAP_READ, 0, 0, 0);
- if (!*baseAddress) {
+ if (!*baseAddress)
+ {
std::cerr << "MapViewOfFile() failed, name = " << fname
<< ", error = " << GetLastError() << std::endl;
- exit(1);
+ exit(EXIT_FAILURE);
}
#endif
uint8_t* data = (uint8_t*)*baseAddress;
- if ( *data++ != *TB_MAGIC++
- || *data++ != *TB_MAGIC++
- || *data++ != *TB_MAGIC++
- || *data++ != *TB_MAGIC) {
+ constexpr uint8_t Magics[][4] = { { 0xD7, 0x66, 0x0C, 0xA5 },
+ { 0x71, 0xE8, 0x23, 0x5D } };
+
+ if (memcmp(data, Magics[type == WDL], 4))
+ {
std::cerr << "Corrupted table in file " << fname << std::endl;
unmap(*baseAddress, *mapping);
return *baseAddress = nullptr, nullptr;
}
- return data;
+ return data + 4; // Skip Magics's header
}
static void unmap(void* baseAddress, uint64_t mapping) {
std::string TBFile::Paths;
-WDLEntry::WDLEntry(const std::string& code) {
+// struct PairsData contains low level indexing information to access TB data.
+// There are 8, 4 or 2 PairsData records for each TBTable, according to type of
+// table and if positions have pawns or not. It is populated at first access.
+struct PairsData {
+ uint8_t flags; // Table flags, see enum TBFlag
+ uint8_t maxSymLen; // Maximum length in bits of the Huffman symbols
+ uint8_t minSymLen; // Minimum length in bits of the Huffman symbols
+ uint32_t blocksNum; // Number of blocks in the TB file
+ size_t sizeofBlock; // Block size in bytes
+ size_t span; // About every span values there is a SparseIndex[] entry
+ Sym* lowestSym; // lowestSym[l] is the symbol of length l with the lowest value
+ LR* btree; // btree[sym] stores the left and right symbols that expand sym
+ uint16_t* blockLength; // Number of stored positions (minus one) for each block: 1..65536
+ uint32_t blockLengthSize; // Size of blockLength[] table: padded so it's bigger than blocksNum
+ SparseEntry* sparseIndex; // Partial indices into blockLength[]
+ size_t sparseIndexSize; // Size of SparseIndex[] table
+ uint8_t* data; // Start of Huffman compressed data
+ std::vector<uint64_t> base64; // base64[l - min_sym_len] is the 64bit-padded lowest symbol of length l
+ std::vector<uint8_t> symlen; // Number of values (-1) represented by a given Huffman symbol: 1..256
+ Piece pieces[TBPIECES]; // Position pieces: the order of pieces defines the groups
+ uint64_t groupIdx[TBPIECES+1]; // Start index used for the encoding of the group's pieces
+ int groupLen[TBPIECES+1]; // Number of pieces in a given group: KRKN -> (3, 1)
+ uint16_t map_idx[4]; // WDLWin, WDLLoss, WDLCursedWin, WDLBlessedLoss (used in DTZ)
+};
+
+// struct TBTable contains indexing information to access the corresponding TBFile.
+// There are 2 types of TBTable, corresponding to a WDL or a DTZ file. TBTable
+// is populated at init time but the nested PairsData records are populated at
+// first access, when the corresponding file is memory mapped.
+template<TBType Type>
+struct TBTable {
+ typedef typename std::conditional<Type == WDL, WDLScore, int>::type Ret;
+
+ static constexpr int Sides = Type == WDL ? 2 : 1;
+
+ std::atomic_bool ready;
+ void* baseAddress;
+ uint8_t* map;
+ uint64_t mapping;
+ Key key;
+ Key key2;
+ int pieceCount;
+ bool hasPawns;
+ bool hasUniquePieces;
+ uint8_t pawnCount[2]; // [Lead color / other color]
+ PairsData items[Sides][4]; // [wtm / btm][FILE_A..FILE_D or 0]
+
+ PairsData* get(int stm, int f) {
+ return &items[stm % Sides][hasPawns ? f : 0];
+ }
+
+ TBTable() : ready(false), baseAddress(nullptr) {}
+ explicit TBTable(const std::string& code);
+ explicit TBTable(const TBTable<WDL>& wdl);
+
+ ~TBTable() {
+ if (baseAddress)
+ TBFile::unmap(baseAddress, mapping);
+ }
+};
+
+template<>
+TBTable<WDL>::TBTable(const std::string& code) : TBTable() {
StateInfo st;
Position pos;
- memset(this, 0, sizeof(WDLEntry));
-
- ready = false;
key = pos.set(code, WHITE, &st).material_key();
- pieceCount = popcount(pos.pieces());
+ pieceCount = pos.count<ALL_PIECES>();
hasPawns = pos.pieces(PAWN);
+ hasUniquePieces = false;
for (Color c = WHITE; c <= BLACK; ++c)
for (PieceType pt = PAWN; pt < KING; ++pt)
if (popcount(pos.pieces(c, pt)) == 1)
hasUniquePieces = true;
- if (hasPawns) {
- // Set the leading color. In case both sides have pawns the leading color
- // is the side with less pawns because this leads to better compression.
- bool c = !pos.count<PAWN>(BLACK)
- || ( pos.count<PAWN>(WHITE)
- && pos.count<PAWN>(BLACK) >= pos.count<PAWN>(WHITE));
+ // Set the leading color. In case both sides have pawns the leading color
+ // is the side with less pawns because this leads to better compression.
+ bool c = !pos.count<PAWN>(BLACK)
+ || ( pos.count<PAWN>(WHITE)
+ && pos.count<PAWN>(BLACK) >= pos.count<PAWN>(WHITE));
- pawnTable.pawnCount[0] = pos.count<PAWN>(c ? WHITE : BLACK);
- pawnTable.pawnCount[1] = pos.count<PAWN>(c ? BLACK : WHITE);
- }
+ pawnCount[0] = pos.count<PAWN>(c ? WHITE : BLACK);
+ pawnCount[1] = pos.count<PAWN>(c ? BLACK : WHITE);
key2 = pos.set(code, BLACK, &st).material_key();
}
-WDLEntry::~WDLEntry() {
+template<>
+TBTable<DTZ>::TBTable(const TBTable<WDL>& wdl) : TBTable() {
- if (baseAddress)
- TBFile::unmap(baseAddress, mapping);
-
- for (int i = 0; i < 2; ++i)
- if (hasPawns)
- for (File f = FILE_A; f <= FILE_D; ++f)
- delete pawnTable.file[i][f].precomp;
- else
- delete pieceTable[i].precomp;
-}
-
-DTZEntry::DTZEntry(const WDLEntry& wdl) {
-
- memset(this, 0, sizeof(DTZEntry));
-
- ready = false;
+ // Use the corresponding WDL table to avoid recalculating all from scratch
key = wdl.key;
key2 = wdl.key2;
pieceCount = wdl.pieceCount;
hasPawns = wdl.hasPawns;
hasUniquePieces = wdl.hasUniquePieces;
+ pawnCount[0] = wdl.pawnCount[0];
+ pawnCount[1] = wdl.pawnCount[1];
+}
+
+// class TBTables creates and keeps ownership of the TBTable objects, one for
+// each TB file found. It supports a fast, hash based, table lookup. Populated
+// at init time, accessed at probe time.
+class TBTables {
+
+ typedef std::tuple<Key, TBTable<WDL>*, TBTable<DTZ>*> Entry;
- if (hasPawns) {
- pawnTable.pawnCount[0] = wdl.pawnTable.pawnCount[0];
- pawnTable.pawnCount[1] = wdl.pawnTable.pawnCount[1];
+ 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 + Overflow];
+
+ std::deque<TBTable<WDL>> wdlTable;
+ std::deque<TBTable<DTZ>> dtzTable;
+
+ void insert(Key key, TBTable<WDL>* wdl, TBTable<DTZ>* dtz) {
+ 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 (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(EXIT_FAILURE);
}
-}
-DTZEntry::~DTZEntry() {
+public:
+ template<TBType Type>
+ TBTable<Type>* get(Key key) {
+ for (const Entry* entry = &hashTable[(uint32_t)key & (Size - 1)]; ; ++entry) {
+ if (std::get<KEY>(*entry) == key || !std::get<Type>(*entry))
+ return std::get<Type>(*entry);
+ }
+ }
- if (baseAddress)
- TBFile::unmap(baseAddress, mapping);
+ void clear() {
+ memset(hashTable, 0, sizeof(hashTable));
+ wdlTable.clear();
+ dtzTable.clear();
+ }
+ size_t size() const { return wdlTable.size(); }
+ void add(const std::vector<PieceType>& pieces);
+};
- if (hasPawns)
- for (File f = FILE_A; f <= FILE_D; ++f)
- delete pawnTable.file[f].precomp;
- else
- delete pieceTable.precomp;
-}
+TBTables TBTables;
-void HashTable::insert(const std::vector<PieceType>& pieces) {
+// If the corresponding file exists two new objects TBTable<WDL> and TBTable<DTZ>
+// are created and added to the lists and hash table. Called at init time.
+void TBTables::add(const std::vector<PieceType>& pieces) {
std::string code;
wdlTable.emplace_back(code);
dtzTable.emplace_back(wdlTable.back());
+ // Insert into the hash keys for both colors: KRvK with KR white and black
insert(wdlTable.back().key , &wdlTable.back(), &dtzTable.back());
insert(wdlTable.back().key2, &wdlTable.back(), &dtzTable.back());
}
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(WDLEntry*, int, File) { return true; }
-
-bool check_dtz_stm(DTZEntry* entry, int stm, File f) {
+bool check_dtz_stm(TBTable<WDL>*, int, File) { return true; }
- int flags = entry->hasPawns ? entry->pawnTable.file[f].precomp->flags
- : entry->pieceTable.precomp->flags;
+bool check_dtz_stm(TBTable<DTZ>* entry, int stm, File f) {
+ auto flags = entry->get(stm, f)->flags;
return (flags & TBFlag::STM) == stm
|| ((entry->key == entry->key2) && !entry->hasPawns);
}
// values 0, 1, 2, ... in order of decreasing frequency. This is done for each
// of the four WDLScore values. The mapping information necessary to reconstruct
// the original values is stored in the TB file and read during map[] init.
-WDLScore map_score(WDLEntry*, File, int value, WDLScore) { return WDLScore(value - 2); }
+WDLScore map_score(TBTable<WDL>*, File, int value, WDLScore) { return WDLScore(value - 2); }
-int map_score(DTZEntry* entry, File f, int value, WDLScore wdl) {
+int map_score(TBTable<DTZ>* entry, File f, int value, WDLScore wdl) {
constexpr int WDLMap[] = { 1, 3, 0, 2, 0 };
- int flags = entry->hasPawns ? entry->pawnTable.file[f].precomp->flags
- : entry->pieceTable.precomp->flags;
+ auto flags = entry->get(0, f)->flags;
- uint8_t* map = entry->hasPawns ? entry->pawnTable.map
- : entry->pieceTable.map;
-
- uint16_t* idx = entry->hasPawns ? entry->pawnTable.file[f].map_idx
- : entry->pieceTable.map_idx;
- if (flags & TBFlag::Mapped)
- value = map[idx[WDLMap[wdl + 2]] + value];
+ uint8_t* map = entry->map;
+ uint16_t* idx = entry->get(0, f)->map_idx;
+ 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.
//
// idx = Binomial[1][s1] + Binomial[2][s2] + ... + Binomial[k][sk]
//
-template<typename Entry, typename T = typename Ret<Entry>::type>
-T do_probe_table(const Position& pos, Entry* entry, WDLScore wdl, ProbeState* result) {
-
- constexpr bool IsWDL = std::is_same<Entry, WDLEntry>::value;
+template<typename T, typename Ret = typename T::Ret>
+Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* result) {
Square squares[TBPIECES];
Piece pieces[TBPIECES];
// In all the 4 tables, pawns are at the beginning of the piece sequence and
// their color is the reference one. So we just pick the first one.
- Piece pc = Piece(item(entry->pawnTable, 0, 0).precomp->pieces[0] ^ flipColor);
+ Piece pc = Piece(entry->get(0, 0)->pieces[0] ^ flipColor);
assert(type_of(pc) == PAWN);
tbFile = file_of(squares[0]);
if (tbFile > FILE_D)
tbFile = file_of(squares[0] ^ 7); // Horizontal flip: SQ_H1 -> SQ_A1
-
- d = item(entry->pawnTable , stm, tbFile).precomp;
- } else
- d = item(entry->pieceTable, stm, tbFile).precomp;
+ }
// DTZ tables are one-sided, i.e. they store positions only for white to
// move or only for black to move, so check for side to move to be stm,
// early exit otherwise.
- if (!IsWDL && !check_dtz_stm(entry, stm, tbFile))
- return *result = CHANGE_STM, T();
+ if (!check_dtz_stm(entry, stm, tbFile))
+ return *result = CHANGE_STM, Ret();
// Now we are ready to get all the position pieces (but the lead pawns) and
// directly map them to the correct color and square.
assert(size >= 2);
+ d = entry->get(stm, tbFile);
+
// Then we reorder the pieces to have the same sequence as the one stored
- // in precomp->pieces[i]: the sequence that ensures the best compression.
+ // in pieces[i]: the sequence that ensures the best compression.
for (int i = leadPawnsCnt; i < size; ++i)
for (int j = i; j < size; ++j)
if (d->pieces[i] == pieces[j])
Square* groupSq = squares + d->groupLen[0];
// Encode remainig pawns then pieces according to square, in ascending order
- bool remainingPawns = entry->hasPawns && entry->pawnTable.pawnCount[1];
+ bool remainingPawns = entry->hasPawns && entry->pawnCount[1];
while (d->groupLen[++next])
{
// pawns/pieces -> remainig pawns -> remaining pieces. In particular the
// first group is at order[0] position and the remaining pawns, when present,
// are at order[1] position.
- bool pp = e.hasPawns && e.pawnTable.pawnCount[1]; // Pawns on both sides
+ bool pp = e.hasPawns && e.pawnCount[1]; // Pawns on both sides
int next = pp ? 2 : 1;
int freeSquares = 64 - d->groupLen[0] - (pp ? d->groupLen[1] : 0);
uint64_t idx = 1;
d->sizeofBlock = 1ULL << *data++;
d->span = 1ULL << *data++;
d->sparseIndexSize = (tbSize + d->span - 1) / d->span; // Round up
- int padding = number<uint8_t, LittleEndian>(data++);
+ auto padding = number<uint8_t, LittleEndian>(data++);
d->blocksNum = number<uint32_t, LittleEndian>(data); data += sizeof(uint32_t);
d->blockLengthSize = d->blocksNum + padding; // Padded to ensure SparseIndex[]
// does not point out of range.
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.
return data + d->symlen.size() * sizeof(LR) + (d->symlen.size() & 1);
}
-template<typename T>
-uint8_t* set_dtz_map(WDLEntry&, T&, uint8_t*, File) { return nullptr; }
+uint8_t* set_dtz_map(TBTable<WDL>&, uint8_t* data, File) { return data; }
-template<typename T>
-uint8_t* set_dtz_map(DTZEntry&, T& p, uint8_t* data, File maxFile) {
+uint8_t* set_dtz_map(TBTable<DTZ>& e, uint8_t* data, File maxFile) {
- p.map = data;
+ e.map = data;
for (File f = FILE_A; f <= maxFile; ++f) {
- if (item(p, 0, f).precomp->flags & TBFlag::Mapped)
- for (int i = 0; i < 4; ++i) { // Sequence like 3,x,x,x,1,x,0,2,x,x
- item(p, 0, f).map_idx[i] = (uint16_t)(data - p.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
}
-template<typename Entry, typename T>
-void do_init(Entry& e, T& p, uint8_t* data) {
-
- const bool IsWDL = std::is_same<Entry, WDLEntry>::value;
+// Populate entry's PairsData records with data from the just memory mapped file.
+// Called at first access.
+template<typename T>
+void set(T& e, uint8_t* data) {
PairsData* d;
data++; // First byte stores flags
- const int sides = IsWDL && (e.key != e.key2) ? 2 : 1;
+ const int sides = T::Sides == 2 && (e.key != e.key2) ? 2 : 1;
const File maxFile = e.hasPawns ? FILE_D : FILE_A;
- bool pp = e.hasPawns && e.pawnTable.pawnCount[1]; // Pawns on both sides
+ bool pp = e.hasPawns && e.pawnCount[1]; // Pawns on both sides
- assert(!pp || e.pawnTable.pawnCount[0]);
+ assert(!pp || e.pawnCount[0]);
for (File f = FILE_A; f <= maxFile; ++f) {
for (int i = 0; i < sides; i++)
- item(p, i, f).precomp = new PairsData();
+ *e.get(i, f) = PairsData();
int order[][2] = { { *data & 0xF, pp ? *(data + 1) & 0xF : 0xF },
{ *data >> 4, pp ? *(data + 1) >> 4 : 0xF } };
for (int k = 0; k < e.pieceCount; ++k, ++data)
for (int i = 0; i < sides; i++)
- item(p, i, f).precomp->pieces[k] = Piece(i ? *data >> 4 : *data & 0xF);
+ e.get(i, f)->pieces[k] = Piece(i ? *data >> 4 : *data & 0xF);
for (int i = 0; i < sides; ++i)
- set_groups(e, item(p, i, f).precomp, order[i], f);
+ set_groups(e, e.get(i, f), order[i], f);
}
data += (uintptr_t)data & 1; // Word alignment
for (File f = FILE_A; f <= maxFile; ++f)
for (int i = 0; i < sides; i++)
- data = set_sizes(item(p, i, f).precomp, data);
+ data = set_sizes(e.get(i, f), data);
- if (!IsWDL)
- data = set_dtz_map(e, p, data, maxFile);
+ data = set_dtz_map(e, data, maxFile);
for (File f = FILE_A; f <= maxFile; ++f)
for (int i = 0; i < sides; i++) {
- (d = item(p, i, f).precomp)->sparseIndex = (SparseEntry*)data;
+ (d = e.get(i, f))->sparseIndex = (SparseEntry*)data;
data += d->sparseIndexSize * sizeof(SparseEntry);
}
for (File f = FILE_A; f <= maxFile; ++f)
for (int i = 0; i < sides; i++) {
- (d = item(p, i, f).precomp)->blockLength = (uint16_t*)data;
+ (d = e.get(i, f))->blockLength = (uint16_t*)data;
data += d->blockLengthSize * sizeof(uint16_t);
}
for (File f = FILE_A; f <= maxFile; ++f)
for (int i = 0; i < sides; i++) {
data = (uint8_t*)(((uintptr_t)data + 0x3F) & ~0x3F); // 64 byte alignment
- (d = item(p, i, f).precomp)->data = data;
+ (d = e.get(i, f))->data = data;
data += d->blocksNum * d->sizeofBlock;
}
}
-template<typename Entry>
-void* init(Entry& e, const Position& pos) {
-
- constexpr bool IsWDL = std::is_same<Entry, WDLEntry>::value;
+// If the TB file corresponding to the given position is already memory mapped
+// then return its base address, otherwise try to memory map and init it. Called
+// at every probe, memory map and init only at first access. Function is thread
+// safe and can be called concurrently.
+template<TBType Type>
+void* mapped(TBTable<Type>& e, const Position& pos) {
static Mutex mutex;
- // Avoid a thread reads 'ready' == true while another is still in do_init(),
- // this could happen due to compiler reordering.
+ // Use 'acquire' to avoid a thread reading 'ready' == true while
+ // another is still working. (compiler reordering may cause this).
if (e.ready.load(std::memory_order_acquire))
- return e.baseAddress;
+ return e.baseAddress; // Could be nullptr if file does not exist
std::unique_lock<Mutex> lk(mutex);
b += std::string(popcount(pos.pieces(BLACK, pt)), PieceToChar[pt]);
}
- constexpr uint8_t TB_MAGIC[][4] = { { 0xD7, 0x66, 0x0C, 0xA5 },
- { 0x71, 0xE8, 0x23, 0x5D } };
-
fname = (e.key == pos.material_key() ? w + 'v' + b : b + 'v' + w)
- + (IsWDL ? ".rtbw" : ".rtbz");
+ + (Type == WDL ? ".rtbw" : ".rtbz");
+
+ uint8_t* data = TBFile(fname).map(&e.baseAddress, &e.mapping, Type);
- uint8_t* data = TBFile(fname).map(&e.baseAddress, &e.mapping, TB_MAGIC[IsWDL]);
if (data)
- e.hasPawns ? do_init(e, e.pawnTable, data) : do_init(e, e.pieceTable, data);
+ set(e, data);
e.ready.store(true, std::memory_order_release);
return e.baseAddress;
}
-template<typename E, typename T = typename Ret<E>::type>
-T probe_table(const Position& pos, ProbeState* result, WDLScore wdl = WDLDraw) {
+template<TBType Type, typename Ret = typename TBTable<Type>::Ret>
+Ret probe_table(const Position& pos, ProbeState* result, WDLScore wdl = WDLDraw) {
- if (!(pos.pieces() ^ pos.pieces(KING)))
- return T(WDLDraw); // KvK
+ if (pos.count<ALL_PIECES>() == 2) // KvK
+ return Ret(WDLDraw);
- E* entry = EntryTable.get<E>(pos.material_key());
+ TBTable<Type>* entry = TBTables.get<Type>(pos.material_key());
- if (!entry || !init(*entry, pos))
- return *result = FAIL, T();
+ if (!entry || !mapped(*entry, pos))
+ return *result = FAIL, Ret();
return do_probe_table(pos, entry, wdl, result);
}
// 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)
value = bestValue;
else
{
- value = probe_table<WDLEntry>(pos, result);
+ value = probe_table<WDL>(pos, result);
if (*result == FAIL)
return WDLDraw;
} // namespace
+
+/// Tablebases::init() is called at startup and after every change to
+/// "SyzygyPath" UCI option to (re)create the various tables. It is not thread
+/// safe, nor it needs to be.
void Tablebases::init(const std::string& paths) {
- EntryTable.clear();
+ TBTables.clear();
MaxCardinality = 0;
TBFile::Paths = paths;
continue; // First on diagonal, second above
else if (!off_A1H8(s1) && !off_A1H8(s2))
- bothOnDiagonal.push_back(std::make_pair(idx, s2));
+ bothOnDiagonal.emplace_back(idx, s2);
else
MapKK[idx][s2] = code++;
// 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
LeadPawnsSize[leadPawnsCnt][f] = idx;
}
+ // Add entries in TB tables if the corresponding ".rtbw" file exsists
for (PieceType p1 = PAWN; p1 < KING; ++p1) {
- EntryTable.insert({KING, p1, KING});
+ TBTables.add({KING, p1, KING});
for (PieceType p2 = PAWN; p2 <= p1; ++p2) {
- EntryTable.insert({KING, p1, p2, KING});
- EntryTable.insert({KING, p1, KING, p2});
+ TBTables.add({KING, p1, p2, KING});
+ TBTables.add({KING, p1, KING, p2});
for (PieceType p3 = PAWN; p3 < KING; ++p3)
- EntryTable.insert({KING, p1, p2, KING, p3});
+ TBTables.add({KING, p1, p2, KING, p3});
for (PieceType p3 = PAWN; p3 <= p2; ++p3) {
- EntryTable.insert({KING, p1, p2, p3, KING});
+ TBTables.add({KING, p1, p2, p3, KING});
+
+ for (PieceType p4 = PAWN; p4 <= p3; ++p4) {
+ TBTables.add({KING, p1, p2, p3, p4, KING});
+
+ 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 <= p3; ++p4)
- EntryTable.insert({KING, p1, p2, p3, p4, KING});
+ for (PieceType p4 = PAWN; p4 < KING; ++p4) {
+ TBTables.add({KING, p1, p2, p3, KING, p4});
- for (PieceType p4 = PAWN; p4 < KING; ++p4)
- EntryTable.insert({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)
for (PieceType p4 = PAWN; p4 <= (p1 == p3 ? p2 : p3); ++p4)
- EntryTable.insert({KING, p1, p2, KING, p3, p4});
+ TBTables.add({KING, p1, p2, KING, p3, p4});
}
}
- sync_cout << "info string Found " << EntryTable.size() << " tablebases" << sync_endl;
+ sync_cout << "info string Found " << TBTables.size() << " tablebases" << sync_endl;
}
// Probe the WDL table for a particular position.
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
if (*result == ZEROING_BEST_MOVE)
return dtz_before_zeroing(wdl);
- int dtz = probe_table<DTZEntry>(pos, result, wdl);
+ int dtz = probe_table<DTZ>(pos, result, wdl);
if (*result == FAIL)
return 0;
// 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];
+ // Obtain 50-move counter for the root position
+ int cnt50 = pos.rule50_count();
- if (generate<LEGAL>(pos, s) == s)
- v = 1;
- }
+ // Check whether a position was repeated since the last zeroing move.
+ bool rep = pos.has_repeated();
- 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));
- }
- }
+ int dtz, bound = Options["Syzygy50MoveRule"] ? 900 : 1;
- 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;
-
- if (dtz > 0)
- wdl = (dtz + cnt50 <= 100) ? WDLWin : WDLCursedWin;
- else if (dtz < 0)
- wdl = (-dtz + cnt50 <= 100) ? WDLLoss : WDLBlessedLoss;
-
- // Determine the score to report to the user.
- score = WDL_to_value[wdl + 2];
-
- // 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