// 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 BookEntry {
+ struct Entry {
uint64_t key;
uint16_t move;
uint16_t count;
};
// 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;
- const Key* ZobCastle = ZobPiece + 12 * 64; // Pieces * squares
- const Key* ZobEnPassant = ZobCastle + 4; // Castle flags
- const Key* ZobTurn = ZobEnPassant + 8; // Number of files
+ }};
- // 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;
+ Key key = 0;
Bitboard b = pos.pieces();
while (b)
{
- // In PolyGlotRandoms[] pieces are stored in the following sequence:
- // BP = 0, WP = 1, BN = 2, WN = 3, ... BK = 10, WK = 11
Square s = pop_lsb(&b);
Piece p = pos.piece_on(s);
- int pieceOfs = 2 * (type_of(p) - 1) + (color_of(p) == WHITE);
- key ^= ZobPiece[64 * pieceOfs + 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(ALL_CASTLES);
while (b)
- key ^= ZobCastle[pop_lsb(&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
-PolyglotBook::PolyglotBook() : RKiss(Time::now() % 10000) {}
+PolyglotBook::PolyglotBook() : rkiss(Time::now() % 10000) {}
PolyglotBook::~PolyglotBook() { if (is_open()) close(); }
return *this;
}
-template<> PolyglotBook& PolyglotBook::operator>>(BookEntry& e) {
+template<> PolyglotBook& PolyglotBook::operator>>(Entry& e) {
return *this >> e.key >> e.move >> e.count >> e.learn;
}
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);
+ Key key = polyglot_key(pos);
- seekg(find_first(key) * sizeof(BookEntry), ios_base::beg);
+ 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 ( (sum && RKiss.rand<unsigned>() % sum < e.count)
+ if ( (sum && rkiss.rand<unsigned>() % sum < e.count)
|| (pickBest && e.count == best))
move = Move(e.move);
}
/// the book file for the given key. Returns the index of the leftmost book
/// entry with the same key as the input.
-size_t PolyglotBook::find_first(uint64_t key) {
+size_t PolyglotBook::find_first(Key key) {
seekg(0, ios::end); // Move pointer to end, so tellg() gets file's size
- size_t low = 0, mid, high = (size_t)tellg() / sizeof(BookEntry) - 1;
- BookEntry e;
+ size_t low = 0, mid, high = (size_t)tellg() / sizeof(Entry) - 1;
+ Entry e;
assert(low <= high);
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)