X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbook.cpp;h=a98acf491f24dba4f4a29562d6ddce7d730f06b9;hp=bae224ba586482e7aa805281dd2bb76ba0b9f232;hb=afadc33fb430abd2ba2783a62180cf971b13652f;hpb=92ca97d121431bb24f3ca5aaa42e3f834bbb3f15 diff --git a/src/book.cpp b/src/book.cpp index bae224ba..a98acf49 100644 --- a/src/book.cpp +++ b/src/book.cpp @@ -49,6 +49,10 @@ Book OpeningBook; namespace { + /// Book entry size in bytes + const int EntrySize = 16; + + /// Random numbers from PolyGlot, used to compute book hash keys. const uint64_t Random64[781] = { @@ -318,26 +322,19 @@ namespace { /// Indices to the Random64[] array - const int RandomPiece = 0; - const int RandomCastle = 768; + const int RandomPiece = 0; + const int RandomCastle = 768; const int RandomEnPassant = 772; - const int RandomTurn = 780; - - - /// Convert pieces to the range 0..1 - - const int PieceTo12[] = { - 0, 0, 2, 4, 6, 8, 10, 0, 0, 1, 3, 5, 7, 9, 11 - }; + const int RandomTurn = 780; /// Prototypes - uint64_t book_key(const Position &pos); + 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); + uint64_t book_castle_key(const Position& pos); + uint64_t book_ep_key(const Position& pos); + uint64_t book_color_key(const Position& pos); uint16_t read_integer16(std::ifstream& file); uint64_t read_integer64(std::ifstream& file); @@ -355,28 +352,30 @@ namespace { Book::Book() : bookSize(0) {} -/// Book::open() opens a book file with a given file name. +/// Book::open() opens a book file with a given file name -void Book::open(const std::string &fName) { +void Book::open(const std::string& fName) { fileName = fName; bookFile.open(fileName.c_str(), std::ifstream::in | std::ifstream::binary); if (!bookFile.is_open()) return; + // get the book size in number of entries bookFile.seekg(0, std::ios::end); - bookSize = bookFile.tellg() / 16; + bookSize = bookFile.tellg() / EntrySize; bookFile.seekg(0, std::ios::beg); if (!bookFile.good()) { std::cerr << "Failed to open book file " << fileName << std::endl; + bookFile.close(); exit(EXIT_FAILURE); } } -/// Book::close() closes the currently open book file. +/// Book::close() closes the currently open book file void Book::close() { @@ -398,51 +397,60 @@ bool Book::is_open() const { const std::string Book::file_name() const { - return bookFile.is_open() ? fileName : ""; + return is_open() ? fileName : ""; } -/// Book::get_move() gets a book move for a given position. Returns +/// Book::get_move() gets a book move for a given position. Returns /// MOVE_NONE if no book move is found. -Move Book::get_move(const Position &pos) const { - if(this->is_open()) { - int bestMove = 0, bestScore = 0, move, score; - uint64_t key = book_key(pos); - BookEntry entry; - - for(int i = this->find_key(key); i < bookSize; i++) { - this->read_entry(entry, i); - if(entry.key != key) - break; - move = entry.move; - score = entry.count; +Move Book::get_move(const Position& pos) const { + + if (!is_open()) + return MOVE_NONE; + + int bookMove = 0, scoresSum = 0; + uint64_t key = book_key(pos); + BookEntry entry; + + // Choose a book move among the possible moves for the given position + for (int i = find_key(key); i < bookSize; i++) + { + read_entry(entry, i); + if (entry.key != key) + break; + + int score = entry.count; + assert(score > 0); - bestScore += score; - if(int(genrand_int32() % bestScore) < score) - bestMove = move; - } + // 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 (int(genrand_int32() % scoresSum) < score) + bookMove = entry.move; + } + if (!bookMove) + return MOVE_NONE; - if(bestMove != 0) { - MoveStack moves[256]; - int n, j; - n = generate_legal_moves(pos, moves); - for(j = 0; j < n; j++) - if((int(moves[j].move) & 07777) == bestMove) + MoveStack moves[256]; + int n = generate_legal_moves(pos, moves); + for (int j = 0; j < n; j++) + if ((int(moves[j].move) & 07777) == bookMove) return moves[j].move; - } - } + 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 +/// 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. int Book::find_key(uint64_t key) const { + int left, right, mid; BookEntry entry; @@ -452,46 +460,46 @@ int Book::find_key(uint64_t key) const { assert(left <= right); - while(left < right) { - mid = (left + right) / 2; - assert(mid >= left && mid < right); + while(left < right) + { + mid = (left + right) / 2; - this->read_entry(entry, mid); + assert(mid >= left && mid < right); - if(key <= entry.key) - right = mid; - else - left = mid + 1; + read_entry(entry, mid); + if (key <= entry.key) + right = mid; + else + left = mid + 1; } - assert(left == right); - this->read_entry(entry, left); - + 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. +/// file. The book entry is copied to the first input parameter. void Book::read_entry(BookEntry& entry, int n) const { assert(n >= 0 && n < bookSize); - assert(bookFile.is_open()); + assert(is_open()); - bookFile.seekg(n*16, std::ios_base::beg); + bookFile.seekg(n * EntrySize, std::ios_base::beg); if (!bookFile.good()) { - std::cerr << "Failed to read book entry at index " << n << std::endl; - exit(EXIT_FAILURE); + std::cerr << "Failed to read book entry at index " << n << std::endl; + bookFile.close(); + exit(EXIT_FAILURE); } - entry.key = read_integer64(bookFile); - entry.move = read_integer16(bookFile); + entry.key = read_integer64(bookFile); + entry.move = read_integer16(bookFile); entry.count = read_integer16(bookFile); - entry.n = read_integer16(bookFile); - entry.sum = read_integer16(bookFile); + entry.n = read_integer16(bookFile); + entry.sum = read_integer16(bookFile); } @@ -501,59 +509,69 @@ void Book::read_entry(BookEntry& entry, int n) const { namespace { - uint64_t book_key(const Position &pos) { + uint64_t book_key(const Position& pos) { + uint64_t result = 0ULL; - for(Color c = WHITE; c <= BLACK; c++) { - Bitboard b = pos.pieces_of_color(c); - Square s; - Piece p; - while(b != EmptyBoardBB) { - s = pop_1st_bit(&b); - p = pos.piece_on(s); - assert(piece_is_ok(p)); - assert(color_of_piece(p) == c); - - result ^= book_piece_key(p, s); - } + for (Color c = WHITE; c <= BLACK; c++) + { + Bitboard b = pos.pieces_of_color(c); + + while (b != EmptyBoardBB) + { + 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) { - return Random64[RandomPiece + (PieceTo12[int(p)]^1)*64 + int(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 book_castle_key(const Position& pos) { + uint64_t result = 0ULL; - 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]; + 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)? - 0ULL : Random64[RandomEnPassant + square_file(pos.ep_square())]; + uint64_t book_ep_key(const Position& pos) { + return (pos.ep_square() == SQ_NONE ? 0ULL : Random64[RandomEnPassant + square_file(pos.ep_square())]); } - uint64_t book_color_key(const Position &pos) { - return (pos.side_to_move() == WHITE)? Random64[RandomTurn] : 0ULL; + uint64_t book_color_key(const Position& pos) { + return (pos.side_to_move() == WHITE ? Random64[RandomTurn] : 0ULL); } @@ -578,11 +596,12 @@ namespace { if (!file.good()) { - std::cerr << "Failed to read " << size << " bytes from book file" - << std::endl; + std::cerr << "Failed to read " << size << " bytes from book file" << std::endl; + file.close(); exit(EXIT_FAILURE); } - // Numbers are stored in little endian format + + // Numbers are stored on disk in big endian format uint64_t n = 0ULL; for (int i = 0; i < size; i++) n = (n << 8) + (unsigned char)buf[i];