/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2014 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
/*
The code in this file is based on the opening book code in PolyGlot
- by Fabien Letouzey. PolyGlot is available under the GNU General
+ by Fabien Letouzey. PolyGlot is available under the GNU General
Public License, and can be downloaded from http://wbec-ridderkerk.nl
*/
-
-////
-//// Includes
-////
-
+#include <algorithm>
#include <cassert>
#include "book.h"
+#include "misc.h"
#include "movegen.h"
using namespace std;
-////
-//// Local definitions
-////
-
namespace {
- /// Book entry size in bytes
- const int EntrySize = 16;
-
-
- /// Random numbers from PolyGlot, used to compute book hash keys
+ // A Polyglot book is a series of "entries" of 16 bytes. All integers are
+ // stored in big-endian format, with the 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;
+ };
- const uint64_t Random64[781] = {
+ // Random numbers from PolyGlot, used to compute book hash keys
+ const union {
+ Key PolyGlotRandoms[781];
+ struct {
+ Key psq[12][64]; // [piece][square]
+ Key castling[4]; // [castling flag]
+ Key enpassant[8]; // [file]
+ Key turn;
+ } Zobrist;
+ } PG = {{
0x9D39247E33776D41ULL, 0x2AF7398005AAA5C7ULL, 0x44DB015024623547ULL,
0x9C15F73E62A76AE2ULL, 0x75834465489C0C89ULL, 0x3290AC3A203001BFULL,
0x0FBBAD1F61042279ULL, 0xE83A908FF2FB60CAULL, 0x0D7E765D58755C10ULL,
0x003A93D8B2806962ULL, 0x1C99DED33CB890A1ULL, 0xCF3145DE0ADD4289ULL,
0xD0E4427A5514FB72ULL, 0x77C621CC9FB3A483ULL, 0x67A34DAC4356550BULL,
0xF8D626AAAF278509ULL
- };
-
-
- /// Indices to the Random64[] array
+ }};
- const int RandomPiece = 0;
- const int RandomCastle = 768;
- const int RandomEnPassant = 772;
- const int RandomTurn = 780;
+ // polyglot_key() returns the PolyGlot hash key of the given position
+ Key polyglot_key(const Position& pos) {
+ Key key = 0;
+ Bitboard b = pos.pieces();
- /// Prototypes
-
- uint64_t book_key(const Position& pos);
- uint64_t book_piece_key(Piece p, Square s);
- uint64_t book_castle_key(const Position& pos);
- uint64_t book_ep_key(const Position& pos);
- uint64_t book_color_key(const Position& pos);
-}
+ while (b)
+ {
+ 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];
+ }
-////
-//// Functions
-////
+ b = pos.can_castle(ANY_CASTLING);
-// C'tor. Make random number generation less deterministic, for book moves
-Book::Book() {
+ while (b)
+ key ^= PG.Zobrist.castling[pop_lsb(&b)];
- for (int i = abs(get_system_time() % 10000); i > 0; i--)
- RKiss.rand<unsigned>();
-}
+ if (pos.ep_square() != SQ_NONE)
+ key ^= PG.Zobrist.enpassant[file_of(pos.ep_square())];
+ if (pos.side_to_move() == WHITE)
+ key ^= PG.Zobrist.turn;
-/// Destructor. Be sure file is closed before we leave.
-
-Book::~Book() {
+ return key;
+ }
- close();
-}
+} // namespace
+PolyglotBook::PolyglotBook() : rkiss(Time::now() % 10000) {}
-/// Book::open() opens a book file with a given file name
+PolyglotBook::~PolyglotBook() { if (is_open()) close(); }
-void Book::open(const string& fName) {
- // Close old file before opening the new
- close();
+/// operator>>() reads sizeof(T) chars from the file's binary byte stream and
+/// converts them into a number of type T. A Polyglot book stores numbers in
+/// big-endian format.
- fileName = fName;
- ifstream::open(fileName.c_str(), ifstream::in | ifstream::binary);
- if (!is_open())
- return;
+template<typename T> PolyglotBook& PolyglotBook::operator>>(T& n) {
- // Get the book size in number of entries
- seekg(0, ios::end);
- bookSize = long(tellg()) / EntrySize;
- seekg(0, ios::beg);
+ n = 0;
+ for (size_t i = 0; i < sizeof(T); ++i)
+ n = T((n << 8) + ifstream::get());
- if (!good())
- {
- cerr << "Failed to open book file " << fileName << endl;
- Application::exit_with_failure();
- }
+ return *this;
}
+template<> PolyglotBook& PolyglotBook::operator>>(Entry& e) {
+ return *this >> e.key >> e.move >> e.count >> e.learn;
+}
-/// Book::close() closes the file only if it is open, otherwise
-/// we can end up in a little mess due to how std::ifstream works.
-void Book::close() {
+/// open() tries to open a book file with the given name after closing any
+/// exsisting one.
- if (is_open())
- ifstream::close();
-}
+bool PolyglotBook::open(const char* fName) {
+ if (is_open()) // Cannot close an already closed file
+ close();
-/// Book::file_name() returns the file name of the currently active book,
-/// or the empty string if no book is open.
+ ifstream::open(fName, ifstream::in | ifstream::binary);
-const string Book::file_name() { // Not const to compile on HP-UX 11.X
-
- return is_open() ? fileName : "";
+ fileName = is_open() ? fName : "";
+ ifstream::clear(); // Reset any error flag to allow a retry ifstream::open()
+ return !fileName.empty();
}
-/// Book::get_move() gets a book move for a given position. Returns
-/// MOVE_NONE if no book move is found.
+/// probe() tries to find a book move for the given position. If no move is
+/// found, it returns MOVE_NONE. If pickBest is true, then it always returns
+/// the highest-rated move, otherwise it randomly chooses one based on the
+/// move score.
-Move Book::get_move(const Position& pos, bool findBestMove) {
+Move PolyglotBook::probe(const Position& pos, const string& fName, bool pickBest) {
- if (!is_open() || bookSize == 0)
+ if (fileName != fName && !open(fName.c_str()))
return MOVE_NONE;
- BookEntry entry;
- int bookMove = MOVE_NONE;
- unsigned scoresSum = 0, bestScore = 0;
- uint64_t key = book_key(pos);
+ Entry e;
+ uint16_t best = 0;
+ unsigned sum = 0;
+ Move move = MOVE_NONE;
+ Key key = polyglot_key(pos);
+
+ seekg(find_first(key) * sizeof(Entry), ios_base::beg);
- // Choose a book move among the possible moves for the given position
- for (int idx = find_key(key); idx < bookSize; idx++)
+ while (*this >> e, e.key == key && good())
{
- read_entry(entry, idx);
- if (entry.key != key)
- break;
-
- unsigned score = entry.count;
-
- // If findBestMove is true choose highest rated book move
- if (findBestMove)
- {
- if (score > bestScore)
- {
- bestScore = score;
- bookMove = entry.move;
- }
- continue;
- }
-
- // Choose book move according to its score. If a move has a very
- // high score it has more probability to be choosen then a one with
- // lower score. Note that first entry is always chosen.
- scoresSum += score;
- if (RKiss.rand<unsigned>() % scoresSum < score)
- bookMove = entry.move;
+ best = max(best, e.count);
+ sum += e.count;
+
+ // Choose book move according to its score. If a move has a very high
+ // score it has a higher probability of being choosen than a move with
+ // a lower score. Note that first entry is always chosen.
+ if ( (!pickBest && sum && rkiss.rand<unsigned>() % sum < e.count)
+ || (pickBest && e.count == best))
+ move = Move(e.move);
}
- if (!bookMove)
+
+ if (!move)
return MOVE_NONE;
- MoveStack mlist[MOVES_MAX];
- MoveStack* last = generate_moves(pos, mlist);
- for (MoveStack* cur = mlist; cur != last; cur++)
- if ((int(cur->move) & 07777) == bookMove)
- return cur->move;
+ // A PolyGlot book move is encoded as follows:
+ //
+ // bit 0- 5: destination square (from 0 to 63)
+ // bit 6-11: origin square (from 0 to 63)
+ // bit 12-14: promotion piece (from KNIGHT == 1 to QUEEN == 4)
+ //
+ // Castling moves follow the "king captures rook" representation. If a book
+ // move is a promotion, we have to convert it to our representation and in
+ // all other cases, we can directly compare with a Move after having masked
+ // out the special Move 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));
+
+ // Add 'special move' flags and verify it is legal
+ for (MoveList<LEGAL> it(pos); *it; ++it)
+ if (move == (*it ^ type_of(*it)))
+ return *it;
return MOVE_NONE;
}
-/// Book::find_key() takes a book key as input, and does a binary search
-/// through the book file for the given key. The index to the first book
-/// entry with the same key as the input is returned. When the key is not
-/// found in the book file, bookSize is returned.
+/// 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.
-int Book::find_key(uint64_t key) {
+size_t PolyglotBook::find_first(Key key) {
- int left, right, mid;
- BookEntry entry;
+ seekg(0, ios::end); // Move pointer to end, so tellg() gets file's size
- // Binary search (finds the leftmost entry)
- left = 0;
- right = bookSize - 1;
+ size_t low = 0, mid, high = (size_t)tellg() / sizeof(Entry) - 1;
+ Entry e;
- assert(left <= right);
+ assert(low <= high);
- while (left < right)
+ while (low < high && good())
{
- mid = (left + right) / 2;
-
- assert(mid >= left && mid < right);
-
- read_entry(entry, mid);
- if (key <= entry.key)
- right = mid;
- else
- left = mid + 1;
- }
+ mid = (low + high) / 2;
- assert(left == right);
+ assert(mid >= low && mid < high);
- read_entry(entry, left);
- return (entry.key == key)? left : bookSize;
-}
-
-
-/// Book::read_entry() takes a BookEntry reference and an integer index as
-/// input, and looks up the opening book entry at the given index in the book
-/// file. The book entry is copied to the first input parameter.
-
-void Book::read_entry(BookEntry& entry, int idx) {
-
- assert(idx >= 0 && idx < bookSize);
- assert(is_open());
-
- seekg(idx * EntrySize, ios_base::beg);
- *this >> entry;
- if (!good())
- {
- cerr << "Failed to read book entry at index " << idx << endl;
- Application::exit_with_failure();
- }
-}
+ seekg(mid * sizeof(Entry), ios_base::beg);
+ *this >> e;
-
-/// Book::read_integer() reads size chars from the file stream
-/// and converts them in an integer number.
-
-uint64_t Book::read_integer(int size) {
-
- char buf[8];
- read(buf, size);
-
- // Numbers are stored on disk as a binary byte stream
- uint64_t n = 0;
- for (int i = 0; i < size; i++)
- n = (n << 8) + (unsigned char)buf[i];
-
- return n;
-}
-
-
-////
-//// Local definitions
-////
-
-namespace {
-
- uint64_t book_key(const Position& pos) {
-
- uint64_t result = 0;
-
- for (Color c = WHITE; c <= BLACK; c++)
- {
- Bitboard b = pos.pieces_of_color(c);
-
- while (b)
- {
- Square s = pop_1st_bit(&b);
- Piece p = pos.piece_on(s);
-
- assert(piece_is_ok(p));
- assert(color_of_piece(p) == c);
-
- result ^= book_piece_key(p, s);
- }
- }
- result ^= book_castle_key(pos);
- result ^= book_ep_key(pos);
- result ^= book_color_key(pos);
- return result;
- }
-
-
- uint64_t book_piece_key(Piece p, Square s) {
-
- /// Convert pieces to the range 0..11
- static const int PieceTo12[] = { 0, 0, 2, 4, 6, 8, 10, 0, 0, 1, 3, 5, 7, 9, 11 };
-
- return Random64[RandomPiece + (PieceTo12[int(p)]^1) * 64 + int(s)];
- }
-
-
- uint64_t book_castle_key(const Position& pos) {
-
- uint64_t result = 0;
-
- if (pos.can_castle_kingside(WHITE))
- result ^= Random64[RandomCastle+0];
-
- if (pos.can_castle_queenside(WHITE))
- result ^= Random64[RandomCastle+1];
-
- if (pos.can_castle_kingside(BLACK))
- result ^= Random64[RandomCastle+2];
-
- if (pos.can_castle_queenside(BLACK))
- result ^= Random64[RandomCastle+3];
-
- return result;
- }
-
-
- uint64_t book_ep_key(const Position& pos) {
- return pos.ep_square() == SQ_NONE ? 0 : Random64[RandomEnPassant + square_file(pos.ep_square())];
+ if (key <= e.key)
+ high = mid;
+ else
+ low = mid + 1;
}
+ assert(low == high);
- uint64_t book_color_key(const Position& pos) {
- return pos.side_to_move() == WHITE ? Random64[RandomTurn] : 0;
- }
+ return low;
}
projects / stockfish / blobdiff