/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
+
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
-
+
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mersenne.h"
#include "movegen.h"
+using namespace std;
////
//// Global variables
namespace {
- /// Random numbers from PolyGlot, used to compute book hash keys.
+ /// Book entry size in bytes
+ const int EntrySize = 16;
+
+
+ /// Random numbers from PolyGlot, used to compute book hash keys
const uint64_t Random64[781] = {
0x9D39247E33776D41ULL, 0x2AF7398005AAA5C7ULL, 0x44DB015024623547ULL,
/// Indices to the Random64[] array
-
- 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 RandomPiece = 0;
+ const int RandomCastle = 768;
+ const int RandomEnPassant = 772;
+ const int RandomTurn = 780;
/// 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);
- uint16_t read_integer16(std::ifstream& file);
- uint64_t read_integer64(std::ifstream& file);
- uint64_t read_integer(std::ifstream& file, int size);
+ 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);
}
////
-/// Constructor
+/// Destructor. Be sure file is closed before we leave.
+
+Book::~Book() {
+
+ close();
+}
-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 string& fName) {
-void Book::open(const std::string &fName) {
+ // Close old file before opening the new
+ close();
fileName = fName;
- bookFile.open(fileName.c_str(), std::ifstream::in | std::ifstream::binary);
- if (!bookFile.is_open())
+ ifstream::open(fileName.c_str(), ifstream::in | ifstream::binary);
+ if (!is_open())
return;
- bookFile.seekg(0, std::ios::end);\r
- bookSize = bookFile.tellg() / 16;
- bookFile.seekg(0, std::ios::beg);
+ // Get the book size in number of entries
+ seekg(0, ios::end);
+ bookSize = tellg() / EntrySize;
+ seekg(0, ios::beg);
- if (!bookFile.good())
+ if (!good())
{
- std::cerr << "Failed to open book file " << fileName << std::endl;
- exit(EXIT_FAILURE);
+ cerr << "Failed to open book file " << fileName << endl;
+ Application::exit_with_failure();
}
}
-/// Book::close() closes the currently open book file.
+/// 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() {
- if (bookFile.is_open())
- bookFile.close();
-}
-
-
-/// Book::is_open() tests whether a book file has been opened.
-
-bool Book::is_open() const {
-
- return bookFile.is_open() && bookSize != 0;
+ if (is_open())
+ ifstream::close();
}
/// Book::file_name() returns the file name of the currently active book,
/// or the empty string if no book is open.
-const std::string Book::file_name() const {
+const 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;
- assert(score > 0);
+Move Book::get_move(const Position& pos) {
- bestScore += score;
- if(int(genrand_int32() % bestScore) < score)
- bestMove = move;
- }
+ if (!is_open() || bookSize == 0)
+ 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)
- return moves[j].move;
- }
+ 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 idx = find_key(key); idx < bookSize; idx++)
+ {
+ read_entry(entry, idx);
+ if (entry.key != key)
+ break;
+
+ int score = entry.count;
+
+ assert(score > 0);
+
+ // 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;
+
+ MoveStack mlist[256];
+ MoveStack* last = generate_legal_moves(pos, mlist);
+ for (MoveStack* cur = mlist; cur != last; cur++)
+ if ((int(cur->move) & 07777) == bookMove)
+ return cur->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 Book::find_key(uint64_t key) {
+
int left, right, mid;
BookEntry entry;
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 {
+void Book::read_entry(BookEntry& entry, int idx) {
- assert(n >= 0 && n < bookSize);
- assert(bookFile.is_open());
+ assert(idx >= 0 && idx < bookSize);
+ assert(is_open());
- bookFile.seekg(n*16, std::ios_base::beg);
- if (!bookFile.good())
+ seekg(idx * EntrySize, ios_base::beg);
+ *this >> entry;
+ if (!good())
{
- std::cerr << "Failed to read book entry at index " << n << std::endl;
- exit(EXIT_FAILURE);
+ cerr << "Failed to read book entry at index " << idx << endl;
+ Application::exit_with_failure();
}
- 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);
+}
+
+
+/// 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 = 0ULL;
+ for (int i = 0; i < size; i++)
+ n = (n << 8) + (unsigned char)buf[i];
+
+ return n;
}
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)
+ {
+ 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];
- return result;
- }
+ if (pos.can_castle_kingside(WHITE))
+ result ^= Random64[RandomCastle+0];
-
- uint64_t book_ep_key(const Position &pos) {
- return (pos.ep_square() == SQ_NONE)?
- 0ULL : Random64[RandomEnPassant + square_file(pos.ep_square())];
- }
+ if (pos.can_castle_queenside(WHITE))
+ result ^= Random64[RandomCastle+1];
-
- uint64_t book_color_key(const Position &pos) {
- return (pos.side_to_move() == WHITE)? Random64[RandomTurn] : 0ULL;
- }
-
-
- uint16_t read_integer16(std::ifstream& file) {
-
- uint64_t n = read_integer(file, 2);
- assert(n == (uint16_t)n);
- return (uint16_t)n;
- }
+ if (pos.can_castle_kingside(BLACK))
+ result ^= Random64[RandomCastle+2];
+ if (pos.can_castle_queenside(BLACK))
+ result ^= Random64[RandomCastle+3];
- uint64_t read_integer64(std::ifstream& file) {
-
- return read_integer(file, 8);
+ return result;
}
- uint64_t read_integer(std::ifstream& file, int size) {
-
- char buf[8];
- file.read(buf, size);
+ uint64_t book_ep_key(const Position& pos) {
+ return (pos.ep_square() == SQ_NONE ? 0ULL : Random64[RandomEnPassant + square_file(pos.ep_square())]);
+ }
- if (!file.good())
- {
- std::cerr << "Failed to read " << size << " bytes from book file"
- << std::endl;
- exit(EXIT_FAILURE);
- }
- // Numbers are stored in little endian format
- uint64_t n = 0ULL;
- for (int i = 0; i < size; i++)
- n = (n << 8) + (unsigned char)buf[i];
- return n;
+ uint64_t book_color_key(const Position& pos) {
+ return (pos.side_to_move() == WHITE ? Random64[RandomTurn] : 0ULL);
}
}
projects / stockfish / blobdiff