WebSVN – Games.Chess Giants – Diff – //engine-stockfish/syzygy/tbprobe.cpp

 */
 #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 <list>
 #include <sstream>
 #include "../movegen.h"
 #include "../position.h"
 #include "../search.h"
 #include "../thread_win32.h"
 #include "../types.h"
+#include "../uci.h"
 #include "tbprobe.h"
 #ifndef _WIN32
 #include <fcntl.h>
 using namespace Tablebases;
 int Tablebases::MaxCardinality;
 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");
-const 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]
+const std::string PieceToChar = " PNBRQK  pnbrqk";
-        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; };
 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); }
-const Value WDL_to_value[] = {
+constexpr Value WDL_to_value[] = {
    -VALUE_MATE + MAX_PLY + 1,
     VALUE_DRAW - 2,
     VALUE_DRAW,
     VALUE_DRAW + 2,
     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)
+{
+    static_assert(std::is_unsigned<T>::value, "Argument of swap_endian not unsigned");
-    char tmp, *c = (char*)&x;
+    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 };
+    static const union { uint32_t i; char c[4]; } Le = { 0x01020304 };
-    const bool IsLittleEndian = (Le.c[0] == 4);
+    static const bool IsLittleEndian = (Le.c[0] == 4);
     T v;
     if ((uintptr_t)addr & (alignof(T) - 1)) // Unaligned pointer (very rare)
         std::memcpy(&v, addr, sizeof(T));
     else
         v = *((T*)addr);
     if (LE != IsLittleEndian)
-        swap_byte(v);
+        swap_endian(v);
     return v;
+}
+// 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 :
-class HashTable {
+           wdl == WDLBlessedLoss ? -101 :
+           wdl == WDLLoss        ? -1   : 0;
+}
+// Return the sign of a number (-1, 0, 1)
-    typedef std::pair<WDLEntry*, DTZEntry*> EntryPair;
+template <typename T> int sign_of(T val) {
-    typedef std::pair<Key, EntryPair> Entry;
+    return (T(0) < val) - (val < T(0));
+}
+// Numbers in little endian used by sparseIndex[] to point into blockLength[]
+struct SparseEntry {
-    static const int TBHASHBITS = 10;
+    char block[4];   // Number of block
-    static const int HSHMAX     = 5;
+    char offset[2];  // Offset within the block
+};
-    Entry hashTable[1 << TBHASHBITS][HSHMAX];
+static_assert(sizeof(SparseEntry) == 6, "SparseEntry must be 6 bytes");
-    std::deque<WDLEntry> wdlTable;
-    std::deque<DTZEntry> dtzTable;
+typedef uint16_t Sym; // Huffman symbol
-    void insert(Key key, WDLEntry* wdl, DTZEntry* dtz) {
+struct LR {
-        Entry* entry = hashTable[key >> (64 - TBHASHBITS)];
+    enum Side { Left, Right };
-        for (int i = 0; i < HSHMAX; ++i, ++entry)
+    uint8_t lr[3]; // The first 12 bits is the left-hand symbol, the second 12
-            if (!entry->second.first || entry->first == key) {
+                   // bits is the right-hand symbol. If symbol has length 1,
-                *entry = std::make_pair(key, std::make_pair(wdl, dtz));
+                   // then the left-hand symbol is the stored value.
-                return;
+    template<Side S>
-            }
+    Sym get() {
-        std::cerr << "HSHMAX too low!" << std::endl;
+        return S == Left  ? ((lr[1] & 0xF) << 8) | lr[0] :
-        exit(1);
+               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>
+static_assert(sizeof(LR) == 3, "LR tree entry must be 3 bytes");
-    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);
+// Tablebases data layout is structured as following:
+//
-      return nullptr;
-  }
-  void clear() {
-      std::memset(hashTable, 0, sizeof(hashTable));
+//  TBFile:   memory maps/unmaps the physical .rtbw and .rtbz files
-      wdlTable.clear();
-      dtzTable.clear();
-  }
-  size_t size() const { return wdlTable.size(); }
+//  TBTable:  one object for each file with corresponding indexing information
-  void insert(const std::vector<PieceType>& pieces);
+//  TBTables: has ownership of TBTable objects, keeping a list and a hash
-};
-HashTable EntryTable;
+// 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;
 public:
     static std::string Paths;
     TBFile(const std::string& f) {
 #ifndef _WIN32
-        const char SepChar = ':';
+        constexpr char SepChar = ':';
 #else
-        const char SepChar = ';';
+        constexpr char SepChar = ';';
 #endif
         std::stringstream ss(Paths);
         std::string path;
         while (std::getline(ss, path, SepChar)) {
+        }
+    }
     // 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());
         close(); // Need to re-open to get native file descriptor
             return *baseAddress = nullptr, nullptr;
         fstat(fd, &statbuf);
         *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) {
             std::cerr << "Could not mmap() " << fname << std::endl;
             exit(1);
             exit(1);
+        }
 #endif
         uint8_t* data = (uint8_t*)*baseAddress;
-        if (   *data++ != *TB_MAGIC++
+        constexpr uint8_t Magics[][4] = { { 0xD7, 0x66, 0x0C, 0xA5 },
-            || *data++ != *TB_MAGIC++
+                                          { 0x71, 0xE8, 0x23, 0x5D } };
-            || *data++ != *TB_MAGIC++
-            || *data++ != *TB_MAGIC) {
+        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) {
 #ifndef _WIN32
+    }
 };
 std::string TBFile::Paths;
+// 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) {}
-WDLEntry::WDLEntry(const std::string& code) {
+    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
+    // 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.
+    // is the side with less pawns because this leads to better compression.
-        bool c =   !pos.count<PAWN>(BLACK)
+    bool c =   !pos.count<PAWN>(BLACK)
-                || (   pos.count<PAWN>(WHITE)
+            || (   pos.count<PAWN>(WHITE)
-                    && 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);
+    pawnCount[0] = pos.count<PAWN>(c ? WHITE : BLACK);
-        pawnTable.pawnCount[1] = pos.count<PAWN>(c ? BLACK : WHITE);
+    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;
+    // Use the corresponding WDL table to avoid recalculating all from scratch
-        else
-            delete pieceTable[i].precomp;
-}
-DTZEntry::DTZEntry(const WDLEntry& wdl) {
-    memset(this, 0, sizeof(DTZEntry));
-    ready = false;
     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.
-    if (hasPawns) {
+class TBTables {
+    typedef std::tuple<Key, TBTable<WDL>*, TBTable<DTZ>*> Entry;
+    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);
-        pawnTable.pawnCount[0] = wdl.pawnTable.pawnCount[0];
+        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) {
-        pawnTable.pawnCount[1] = wdl.pawnTable.pawnCount[1];
+                swap(entry, hashTable[bucket]);
+                key = otherKey;
+                homeBucket = otherHomeBucket;
+            }
+        }
+        std::cerr << "TB hash table size too low!" << std::endl;
+        exit(1);
+    }
-}
+public:
+    template<TBType Type>
-DTZEntry::~DTZEntry() {
+    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)
+    void clear() {
-        TBFile::unmap(baseAddress, mapping);
+        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)
+TBTables TBTables;
-        for (File f = FILE_A; f <= FILE_D; ++f)
-            delete pawnTable.file[f].precomp;
-    else
-        delete pieceTable.precomp;
-}
+// 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 HashTable::insert(const std::vector<PieceType>& pieces) {
+void TBTables::add(const std::vector<PieceType>& pieces) {
     std::string code;
     for (PieceType pt : pieces)
         code += PieceToChar[pt];
     MaxCardinality = std::max((int)pieces.size(), MaxCardinality);
     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());
+}
 // TB tables are compressed with canonical Huffman code. The compressed data is divided into
     // with index I(k), where:
     //
     //       I(k) = k * d->span + d->span / 2      (1)
     // First step is to get the 'k' of the I(k) nearest to our idx, using definition (1)
-    uint32_t k = (uint32_t) (idx / d->span); // Pierre-Marie Baty -- added type cast
+    uint32_t k = idx / d->span;
     // Then we read the corresponding SparseIndex[] entry
     uint32_t block = number<uint32_t, LittleEndian>(&d->sparseIndex[k].block);
     int offset     = number<uint16_t, LittleEndian>(&d->sparseIndex[k].offset);
     while (offset > d->blockLength[block])
         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
     // is at the beginning of this 64 bits sequence.
     uint64_t buf64 = number<uint64_t, BigEndian>(ptr); ptr += 2;
             ++len;
         // All the symbols of a given length are consecutive integers (numerical
         // sequence property), so we can compute the offset of our symbol of
         // length len, stored at the beginning of buf64.
-        sym = (Sym) ((buf64 - d->base64[len]) >> (64 - len - d->minSymLen)); // Pierre-Marie Baty -- added type cast
+        sym = (buf64 - d->base64[len]) >> (64 - len - d->minSymLen);
         // Now add the value of the lowest symbol of length len to get our symbol
         sym += number<Sym, LittleEndian>(&d->lowestSym[len]);
         // If our offset is within the number of values represented by symbol sym
             offset -= d->symlen[left] + 1;
             sym = d->btree[sym].get<LR::Right>();
+        }
+    }
-    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(TBTable<WDL>*, int, File) { return true; }
-bool check_dtz_stm(DTZEntry* entry, int stm, File f) {
+bool check_dtz_stm(TBTable<DTZ>* entry, int stm, File f) {
-    int flags = entry->hasPawns ? entry->pawnTable.file[f].precomp->flags
-                                : entry->pieceTable.precomp->flags;
+    auto flags = entry->get(stm, f)->flags;
     return   (flags & TBFlag::STM) == stm
           || ((entry->key == entry->key2) && !entry->hasPawns);
+}
 // DTZ scores are sorted by frequency of occurrence and then assigned the
 // 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) {
-    const int WDLMap[] = { 1, 3, 0, 2, 0 };
+    constexpr int WDLMap[] = { 1, 3, 0, 2, 0 };
-    int flags = entry->hasPawns ? entry->pawnTable.file[f].precomp->flags
+    auto flags = entry->get(0, f)->flags;
-                                : entry->pieceTable.precomp->flags;
-    uint8_t* map = entry->hasPawns ? entry->pawnTable.map
+    uint8_t* map = entry->map;
-                                   : entry->pieceTable.map;
-    uint16_t* idx = entry->hasPawns ? entry->pawnTable.file[f].map_idx
+    uint16_t* idx = entry->get(0, f)->map_idx;
-                                    : entry->pieceTable.map_idx;
+    if (flags & TBFlag::Mapped) {
-    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];
+            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.
     if (   (wdl == WDLWin  && !(flags & TBFlag::WinPlies))
         || (wdl == WDLLoss && !(flags & TBFlag::LossPlies))
 // encode k pieces of same type and color, first sort the pieces by square in
 // ascending order s1 <= s2 <= ... <= sk then compute the unique index as:
 //
 //      idx = Binomial[1][s1] + Binomial[2][s2] + ... + Binomial[k][sk]
 //
-template<typename Entry, typename T = typename Ret<Entry>::type>
+template<typename T, typename Ret = typename T::Ret>
-T do_probe_table(const Position& pos, Entry* entry, WDLScore wdl, ProbeState* result) {
+Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* result) {
-    const bool IsWDL = std::is_same<Entry, WDLEntry>::value;
     Square squares[TBPIECES];
     Piece pieces[TBPIECES];
     uint64_t idx;
     int next = 0, size = 0, leadPawnsCnt = 0;
     // MapPawns[] value, that is the one most toward the edges and with lowest rank.
     if (entry->hasPawns) {
         // 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);
         leadPawns = b = pos.pieces(color_of(pc), PAWN);
         do
         std::swap(squares[0], *std::max_element(squares, squares + leadPawnsCnt, pawns_comp));
         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))
+    if (!check_dtz_stm(entry, stm, tbFile))
-        return *result = CHANGE_STM, T();
+        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.
     b = pos.pieces() ^ leadPawns;
     do {
         squares[size] = s ^ flipSquares;
         pieces[size++] = Piece(pos.piece_on(s) ^ flipColor);
     } while (b);
     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])
+            {
                 std::swap(pieces[i], pieces[j]);
 encode_remaining:
     idx *= d->groupIdx[0];
     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])
+    {
         std::sort(groupSq, groupSq + d->groupLen[next]);
         uint64_t n = 0;
     // This ensures unique encoding for the whole position. The order of the
     // groups is a per-table parameter and could not follow the canonical leading
     // 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;
     for (int k = 0; next < n || k == order[0] || k == order[1]; ++k)
     // element stores the biggest index that is the tb size.
     uint64_t tbSize = d->groupIdx[std::find(d->groupLen, d->groupLen + 7, 0) - d->groupLen];
     d->sizeofBlock = 1ULL << *data++;
     d->span = 1ULL << *data++;
-    d->sparseIndexSize = (size_t) ((tbSize + d->span - 1) / d->span); // Round up // Pierre-Marie Baty -- added type cast
+    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->maxSymLen = *data++;
     d->minSymLen = *data++;
     data += d->base64.size() * sizeof(Sym);
     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.
     // See http://www.larsson.dogma.net/dcc99.pdf
     std::vector<bool> visited(d->symlen.size());
             d->symlen[sym] = set_symlen(d, sym, visited);
     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) {
+        auto flags = e.get(0, f)->flags;
-        if (item(p, 0, f).precomp->flags & TBFlag::Mapped)
+        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
+                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);
+                    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;
-                data += *data + 1;
+                }
+            }
+            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
+}
+// Populate entry's PairsData records with data from the just memory mapped file.
+// Called at first access.
-template<typename Entry, typename T>
+template<typename T>
-void do_init(Entry& e, T& p, uint8_t* data) {
+void set(T& e, uint8_t* data) {
-    const bool IsWDL = std::is_same<Entry, WDLEntry>::value;
     PairsData* d;
     enum { Split = 1, HasPawns = 2 };
     assert(e.hasPawns        == !!(*data & HasPawns));
     assert((e.key != e.key2) == !!(*data & Split));
     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;
+    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 (File f = FILE_A; f <= maxFile; ++f) {
-        for (int i = 0; i < Sides; i++)
+        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 } };
         data += 1 + pp;
         for (int k = 0; k < e.pieceCount; ++k, ++data)
-            for (int i = 0; i < Sides; i++)
+            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)
+        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 (File f = FILE_A; f <= maxFile; ++f)
-        for (int i = 0; i < Sides; i++)
+        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 (File f = FILE_A; f <= maxFile; ++f)
-        for (int i = 0; i < Sides; i++) {
+        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 (File f = FILE_A; f <= maxFile; ++f)
-        for (int i = 0; i < Sides; i++) {
+        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 (File f = FILE_A; f <= maxFile; ++f)
-        for (int i = 0; i < Sides; i++) {
+        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;
+        }
+}
+// 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<typename Entry>
+template<TBType Type>
-void* init(Entry& e, const Position& pos) {
+void* mapped(TBTable<Type>& e, const Position& pos) {
-    const bool IsWDL = std::is_same<Entry, WDLEntry>::value;
     static Mutex mutex;
-    // Avoid a thread reads 'ready' == true while another is still in do_init(),
+    // Use 'aquire' to avoid a thread reads 'ready' == true while another is
-    // this could happen due to compiler reordering.
+    // still working, this could happen due to compiler reordering.
     if (e.ready.load(std::memory_order_acquire))
-        return e.baseAddress;
+        return e.baseAddress; // Could be nullptr if file does not exsist
     std::unique_lock<Mutex> lk(mutex);
     if (e.ready.load(std::memory_order_relaxed)) // Recheck under lock
         return e.baseAddress;
     std::string fname, w, b;
     for (PieceType pt = KING; pt >= PAWN; --pt) {
         w += std::string(popcount(pos.pieces(WHITE, pt)), PieceToChar[pt]);
         b += std::string(popcount(pos.pieces(BLACK, pt)), PieceToChar[pt]);
+    }
-    const 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>
+template<TBType Type, typename Ret = typename TBTable<Type>::Ret>
-T probe_table(const Position& pos, ProbeState* result, WDLScore wdl = WDLDraw) {
+Ret probe_table(const Position& pos, ProbeState* result, WDLScore wdl = WDLDraw) {
-    if (!(pos.pieces() ^ pos.pieces(KING)))
+    if (pos.count<ALL_PIECES>() == 2) // KvK
-        return T(WDLDraw); // 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))
+    if (!entry || !mapped(*entry, pos))
-        return *result = FAIL, T();
+        return *result = FAIL, Ret();
     return do_probe_table(pos, entry, wdl, result);
+}
 // For a position where the side to move has a winning capture it is not necessary
 // If the position is won, then the TB needs to store a win value. But if the
 // position is drawn, the TB may store a loss value if that is better for compression.
 // 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;
     StateInfo st;
             continue;
         moveCount++;
         pos.do_move(move, st);
-        value = -search(pos, result);
+        value = -search<false>(pos, result);
         pos.undo_move(move);
         if (*result == FAIL)
             return WDLDraw;
     if (noMoreMoves)
         value = bestValue;
     else
+    {
-        value = probe_table<WDLEntry>(pos, result);
+        value = probe_table<WDL>(pos, result);
         if (*result == FAIL)
             return WDLDraw;
+    }
     return *result = OK, value;
+}
 } // 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;
-    if (paths.empty() || paths == "") // Pierre-Marie Baty -- was: || paths == "<empty>"
+    if (paths.empty() || paths == "<empty>")
         return;
     // MapB1H1H7[] encodes a square below a1-h8 diagonal to 0..27
     int code = 0;
     for (Square s = SQ_A1; s <= SQ_H8; ++s)
                     else if (!off_A1H8(s1) && off_A1H8(s2) > 0)
                         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++;
+            }
     // available squares when the leading one is in 's'. Moreover the pawn with
     // highest MapPawns[] is the leading pawn, the one nearest the edge and,
     // 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
+    // Init the tables for the encoding of leading pawns group: with 7-men TB we
-    // can have up to 4 leading pawns (KPPPPK).
+    // can have up to 5 leading pawns (KPPPPPK).
-    for (int leadPawnsCnt = 1; leadPawnsCnt <= 4; ++leadPawnsCnt)
+    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
             // by file, so we can reuse the same index for different files.
             int idx = 0;
+            }
             // After a file is traversed, store the cumulated per-file index
             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});
+            TBTables.add({KING, p1, p2, KING});
-            EntryTable.insert({KING, p1, KING, p2});
+            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 p4 = PAWN; p4 <= p3; ++p4)
+                    for (PieceType p5 = PAWN; p5 <= p4; ++p5)
-                    EntryTable.insert({KING, p1, p2, p3, p4, KING});
+                        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)
+                for (PieceType p4 = PAWN; p4 < KING; ++p4) {
-                    EntryTable.insert({KING, p1, p2, p3, 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)
                 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.
 // If *result != FAIL, the probe was successful.
 // The return value is from the point of view of the side to move:
 //  1 : win, but draw under 50-move rule
 //  2 : win
 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.
 // If *result != FAIL, the probe was successful.
 // 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
 //
 // The return value n can be off by 1: a return value -n can mean a loss
     // DTZ stores a 'don't care' value in this case, or even a plain wrong
     // one as in case the best move is a losing ep, so it cannot be probed.
     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;
     if (*result != CHANGE_STM)
         // For zeroing moves we want the dtz of the move _before_ doing it,
         // 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 the move mates, force minDTZ to 1
-        if (*result == FAIL)
+        if (dtz == 1 && pos.checkers() && MoveList<LEGAL>(pos).size() == 0)
-            return 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.
         if (!zeroing)
             dtz += sign_of(dtz);
         // Skip the draws and if we are winning only pick positive dtz
         if (dtz < minDTZ && sign_of(dtz) == sign_of(wdl))
             minDTZ = dtz;
+        pos.undo_move(move);
+        if (*result == FAIL)
+            return 0;
+    }
-    // Special handle a mate position, when there are no legal moves, in this
+    // When there are no legal moves, the position is mate: we return -1
-    // 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);
-        if (e < i)
-            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;
-    }
-}
-// Use the DTZ tables to filter out moves that don't preserve the win or draw.
+// Use the DTZ tables to rank root moves.
-// If the position is lost, but DTZ is fairly high, only keep moves that
-// maximise DTZ.
 //
-// A return value false indicates that not all probes were successful and that
+// A return value false indicates that not all probes were successful.
-// no moves were filtered out.
-bool Tablebases::root_probe(Position& pos, Search::RootMoves& rootMoves, Value& score)
+bool Tablebases::root_probe(Position& pos, Search::RootMoves& rootMoves) {
-{
-    assert(rootMoves.size());
     ProbeState result;
-    int dtz = probe_dtz(pos, &result);
+    StateInfo st;
-    if (result == FAIL)
+    // Obtain 50-move counter for the root position
-        return false;
+    int cnt50 = pos.rule50_count();
+    // Check whether a position was repeated since the last zeroing move.
-    StateInfo st;
+    bool rep = pos.has_repeated();
-    // Probe each move
-    for (size_t i = 0; i < rootMoves.size(); ++i) {
+    int dtz, bound = Options["Syzygy50MoveRule"] ? 900 : 1;
-        Move move = rootMoves[i].pv[0];
-        pos.do_move(move, st);
-        int v = 0;
-        if (pos.checkers() && dtz > 0) {
+    // Probe and rank each move
+    for (auto& m : rootMoves)
+    {
-            ExtMove s[MAX_MOVES];
+        pos.do_move(m.pv[0], st);
+        // 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);
+        }
+        else
+        {
+            // Otherwise, take dtz for the new position and correct by 1 ply
-            if (generate<LEGAL>(pos, s) == s)
+            dtz = -probe_dtz(pos, &result);
-                v = 1;
+            dtz =  dtz > 0 ? dtz + 1
+                 : dtz < 0 ? dtz - 1 : dtz;
+        }
+        // Make sure that a mating move is assigned a dtz value of 1
-        if (!v) {
+        if (   pos.checkers()
-            if (st.rule50 != 0) {
+            && dtz == 2
-                v = -probe_dtz(pos, &result);
+            && MoveList<LEGAL>(pos).size() == 0)
+            dtz = 1;
-                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);
+        pos.undo_move(m.pv[0]);
         if (result == FAIL)
             return false;
-        rootMoves[i].score = (Value)v;
+        // 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;
-    // Obtain 50-move counter for the root position.
-    // In Stockfish there seems to be no clean way, so we do it like this:
+        // Determine the score to be displayed for this move. Assign at least
-    int cnt50 = st.previous ? st.previous->rule50 : 0;
-    // Use 50-move counter to determine whether the root position is
+        // 1 cp to cursed wins and let it grow to 49 cp as the positions gets
-    // won, lost or drawn.
+        // closer to a real win.
-    WDLScore wdl = WDLDraw;
-    if (dtz > 0)
-        wdl = (dtz + cnt50 <= 100) ? WDLWin : WDLCursedWin;
+        m.tbScore =  r >= bound ? VALUE_MATE - MAX_PLY - 1
-    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);
+                   : r >  0     ? Value((std::max( 3, r - 800) * int(PawnValueEg)) / 200)
-    else if (wdl == WDLBlessedLoss && dtz >= -100)
+                   : r == 0     ? VALUE_DRAW
-        score = -(Value)(((200 + dtz - cnt50) * int(PawnValueEg)) / 200);
+                   : r > -bound ? Value((std::min(-3, r + 800) * 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;
-            if (v > 0 && v < best)
-                best = v;
-        }
-        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 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;
-            if (v < best)
-                best = v;
-        }
-        // Try all moves, unless we approach or have a 50-move rule draw.
-        if (-best * 2 + cnt50 < 100)
-            return true;
-        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];
+                   :             -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
+// A return value false indicates that not all probes were successful.
-// no moves were filtered out.
-bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves, Value& score)
+bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves) {
-{
-    ProbeState result;
-    WDLScore wdl = Tablebases::probe_wdl(pos, &result);
+    static const int WDL_to_rank[] = { -1000, -899, 0, 899, 1000 };
-    if (result == FAIL)
+    ProbeState result;
-        return false;
+    StateInfo st;
-    score = WDL_to_value[wdl + 2];
+    bool rule50 = Options["Syzygy50MoveRule"];
+    // Probe and rank each move
-    StateInfo st;
+    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)
+        if (!rule50)
-            best = v;
+            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;
+}

Subversion Repositories Games.Chess Giants

Games.Chess Giants//engine-stockfish/syzygy/tbprobe.cpp – Rev 176 → 185