/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
namespace {
+ // A Polyglot book is a series of "entries" of 16 bytes. All integers are
+ // stored in big-endian format, with highest byte first (regardless of size).
+ // The entries are ordered according to the key in ascending order.
+ struct Entry {
+ uint64_t key;
+ uint16_t move;
+ uint16_t count;
+ uint32_t learn;
+ };
+
// Random numbers from PolyGlot, used to compute book hash keys
- const Key PolyGlotRandoms[781] = {
+ const union {
+ Key PolyGlotRandoms[781];
+ struct {
+ Key psq[12][64]; // [piece][square]
+ Key castle[4]; // [castle right]
+ Key enpassant[8]; // [file]
+ Key turn;
+ } Zobrist;
+ } PG = {{
0x9D39247E33776D41ULL, 0x2AF7398005AAA5C7ULL, 0x44DB015024623547ULL,
0x9C15F73E62A76AE2ULL, 0x75834465489C0C89ULL, 0x3290AC3A203001BFULL,
0x0FBBAD1F61042279ULL, 0xE83A908FF2FB60CAULL, 0x0D7E765D58755C10ULL,
0x003A93D8B2806962ULL, 0x1C99DED33CB890A1ULL, 0xCF3145DE0ADD4289ULL,
0xD0E4427A5514FB72ULL, 0x77C621CC9FB3A483ULL, 0x67A34DAC4356550BULL,
0xF8D626AAAF278509ULL
- };
-
- // Offsets to the PolyGlotRandoms[] array of zobrist keys
- const Key* ZobPiece = PolyGlotRandoms + 0;
- const Key* ZobCastle = PolyGlotRandoms + 768;
- const Key* ZobEnPassant = PolyGlotRandoms + 772;
- const Key* ZobTurn = PolyGlotRandoms + 780;
-
- // PieceOffset is calculated as 64 * (PolyPiece ^ 1) where PolyPiece
- // is: BP = 0, WP = 1, BN = 2, WN = 3 ... BK = 10, WK = 11
- const int PieceOffset[] = { 0, 64, 192, 320, 448, 576, 704, 0,
- 0, 0, 128, 256, 384, 512, 640 };
+ }};
- // book_key() returns the PolyGlot hash key of the given position
- uint64_t book_key(const Position& pos) {
+ // polyglot_key() returns the PolyGlot hash key of the given position
+ Key polyglot_key(const Position& pos) {
- uint64_t key = 0;
- Bitboard b = pos.occupied_squares();
+ Key key = 0;
+ Bitboard b = pos.pieces();
while (b)
{
- Square s = pop_1st_bit(&b);
- key ^= ZobPiece[PieceOffset[pos.piece_on(s)] + s];
+ Square s = pop_lsb(&b);
+ Piece p = pos.piece_on(s);
+
+ // PolyGlot pieces are: BP = 0, WP = 1, BN = 2, ... BK = 10, WK = 11
+ key ^= PG.Zobrist.psq[2 * (type_of(p) - 1) + (color_of(p) == WHITE)][s];
}
- b = (pos.can_castle(WHITE_OO) << 0) | (pos.can_castle(WHITE_OOO) << 1)
- | (pos.can_castle(BLACK_OO) << 2) | (pos.can_castle(BLACK_OOO) << 3);
+ b = pos.can_castle(ALL_CASTLES);
while (b)
- key ^= ZobCastle[pop_1st_bit(&b)];
+ key ^= PG.Zobrist.castle[pop_lsb(&b)];
if (pos.ep_square() != SQ_NONE)
- key ^= ZobEnPassant[file_of(pos.ep_square())];
+ key ^= PG.Zobrist.enpassant[file_of(pos.ep_square())];
if (pos.side_to_move() == WHITE)
- key ^= ZobTurn[0];
+ key ^= PG.Zobrist.turn;
return key;
}
} // namespace
-Book::Book() : size(0) {
-
- for (int i = abs(system_time() % 10000); i > 0; i--)
- RKiss.rand<unsigned>(); // Make random number generation less deterministic
-}
+PolyglotBook::PolyglotBook() : rkiss(Time::now() % 10000) {}
-Book::~Book() { if (is_open()) close(); }
+PolyglotBook::~PolyglotBook() { if (is_open()) close(); }
-/// Book::operator>>() reads sizeof(T) chars from the file's binary byte stream
-/// and converts them in a number of type T. A Polyglot book stores numbers in
+/// operator>>() reads sizeof(T) chars from the file's binary byte stream and
+/// converts them in a number of type T. A Polyglot book stores numbers in
/// big-endian format.
-template<typename T> Book& Book::operator>>(T& n) {
+template<typename T> PolyglotBook& PolyglotBook::operator>>(T& n) {
n = 0;
for (size_t i = 0; i < sizeof(T); i++)
return *this;
}
-template<> Book& Book::operator>>(BookEntry& e) {
+template<> PolyglotBook& PolyglotBook::operator>>(Entry& e) {
return *this >> e.key >> e.move >> e.count >> e.learn;
}
-/// Book::open() tries to open a book file with the given name after closing
-/// any exsisting one.
+/// open() tries to open a book file with the given name after closing any
+/// exsisting one.
-bool Book::open(const char* fName) {
-
- fileName = "";
+bool PolyglotBook::open(const char* fName) {
if (is_open()) // Cannot close an already closed file
close();
- ifstream::open(fName, ifstream::in | ifstream::binary | ios::ate);
-
- if (!is_open())
- return false; // Silently fail if the file is not found
+ ifstream::open(fName, ifstream::in | ifstream::binary);
- // Get the book size in number of entries, we are already at the end of file
- size = tellg() / sizeof(BookEntry);
-
- if (!good())
- {
- cerr << "Failed to open book file " << fName << endl;
- exit(EXIT_FAILURE);
- }
-
- fileName = fName; // Set only if successful
- return true;
+ fileName = is_open() ? fName : "";
+ ifstream::clear(); // Reset any error flag to allow retry ifstream::open()
+ return !fileName.empty();
}
-/// Book::probe() tries to find a book move for the given position. If no move
-/// is found returns MOVE_NONE. If pickBest is true returns always the highest
+/// probe() tries to find a book move for the given position. If no move is
+/// found returns MOVE_NONE. If pickBest is true returns always the highest
/// rated move, otherwise randomly chooses one, based on the move score.
-Move Book::probe(const Position& pos, const string& fName, bool pickBest) {
+Move PolyglotBook::probe(const Position& pos, const string& fName, bool pickBest) {
+
+ if (fileName != fName && !open(fName.c_str()))
+ return MOVE_NONE;
- BookEntry e;
+ Entry e;
uint16_t best = 0;
unsigned sum = 0;
Move move = MOVE_NONE;
- uint64_t key = book_key(pos);
-
- if (fileName != fName && !open(fName.c_str()))
- return MOVE_NONE;
+ Key key = polyglot_key(pos);
- binary_search(key);
+ seekg(find_first(key) * sizeof(Entry), ios_base::beg);
while (*this >> e, e.key == key && good())
{
// Choose book move according to its score. If a move has a very
// high score it has higher probability to be choosen than a move
// with lower score. Note that first entry is always chosen.
- if ( (RKiss.rand<unsigned>() % sum < e.count)
+ if ( (sum && rkiss.rand<unsigned>() % sum < e.count)
|| (pickBest && e.count == best))
move = Move(e.move);
}
// the special Move's flags (bit 14-15) that are not supported by PolyGlot.
int pt = (move >> 12) & 7;
if (pt)
- move = make_promotion(from_sq(move), to_sq(move), PieceType(pt + 1));
+ move = make<PROMOTION>(from_sq(move), to_sq(move), PieceType(pt + 1));
// Add 'special move' flags and verify it is legal
- for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
- if (move == (ml.move() & 0x3FFF))
- return ml.move();
+ for (MoveList<LEGAL> it(pos); *it; ++it)
+ if (move == (*it ^ type_of(*it)))
+ return *it;
return MOVE_NONE;
}
-/// Book::binary_search() takes a book key as input, and does a binary search
-/// through the book file for the given key. File stream current position is set
-/// to the leftmost book entry with the same key as the input.
+/// find_first() takes a book key as input, and does a binary search through
+/// the book file for the given key. Returns the index of the leftmost book
+/// entry with the same key as the input.
-void Book::binary_search(uint64_t key) {
+size_t PolyglotBook::find_first(Key key) {
- size_t left, right, mid;
- BookEntry e;
+ seekg(0, ios::end); // Move pointer to end, so tellg() gets file's size
- left = 0;
- right = size - 1;
+ size_t low = 0, mid, high = (size_t)tellg() / sizeof(Entry) - 1;
+ Entry e;
- assert(left <= right);
+ assert(low <= high);
- while (left < right && good())
+ while (low < high && good())
{
- mid = (left + right) / 2;
+ mid = (low + high) / 2;
- assert(mid >= left && mid < right);
+ assert(mid >= low && mid < high);
- seekg(mid * sizeof(BookEntry), ios_base::beg);
+ seekg(mid * sizeof(Entry), ios_base::beg);
*this >> e;
if (key <= e.key)
- right = mid;
+ high = mid;
else
- left = mid + 1;
+ low = mid + 1;
}
- assert(left == right);
+ assert(low == high);
- seekg(left * sizeof(BookEntry), ios_base::beg);
+ return low;
}
projects / stockfish / blobdiff