/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ 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
- Glaurung is free software: you can redistribute it and/or modify
+ 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.
-
- Glaurung is distributed in the hope that it will be useful,
+
+ 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/>.
*/
/*
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 <cassert>
-#include <cstdio>
+#include <iostream>
#include "book.h"
-#include "mersenne.h"
#include "movegen.h"
-
-////
-//// Global variables
-////
-
-Book OpeningBook;
-
-
-////
-//// Local definitions
-////
+using namespace std;
namespace {
- /// Random numbers from PolyGlot, used to compute book hash keys.
-
+ // Random numbers from PolyGlot, used to compute book hash keys
const uint64_t Random64[781] = {
0x9D39247E33776D41ULL, 0x2AF7398005AAA5C7ULL, 0x44DB015024623547ULL,
0x9C15F73E62A76AE2ULL, 0x75834465489C0C89ULL, 0x3290AC3A203001BFULL,
0xF8D626AAAF278509ULL
};
+ // Indices to the Random64[] array
+ const int PieceIdx = 0;
+ const int CastleIdx = 768;
+ const int EnPassantIdx = 772;
+ const int TurnIdx = 780;
- /// Indices to the Random64[] array
-
- const int RandomPiece = 0;
- const int RandomCastle = 768;
- const int RandomEnPassant = 772;
- const int RandomTurn = 780;
+ // book_key() builds up a PolyGlot hash key out of a position
+ uint64_t book_key(const Position& pos) {
-
- /// 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
- };
+ // Piece offset is calculated as (64 * PolyPieceType + square), where
+ // PolyPieceType is: BP = 0, WP = 1, BN = 2, WN = 3 .... BK = 10, WK = 11
+ static const int PieceToPoly[] = { 0, 1, 3, 5, 7, 9, 11, 0, 0, 0, 2, 4, 6, 8, 10 };
+ uint64_t result = 0;
+ Bitboard b = pos.occupied_squares();
- /// 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_1st_bit(&b);
+ int p = PieceToPoly[int(pos.piece_on(s))];
+ result ^= Random64[PieceIdx + 64 * p + int(s)];
+ }
- uint64_t read_integer(FILE *file, int size);
+ if (pos.can_castle_kingside(WHITE))
+ result ^= Random64[CastleIdx + 0];
-}
+ if (pos.can_castle_queenside(WHITE))
+ result ^= Random64[CastleIdx + 1];
+
+ if (pos.can_castle_kingside(BLACK))
+ result ^= Random64[CastleIdx + 2];
+ if (pos.can_castle_queenside(BLACK))
+ result ^= Random64[CastleIdx + 3];
-////
-//// Functions
-////
+ if (pos.ep_square() != SQ_NONE)
+ result ^= Random64[EnPassantIdx + square_file(pos.ep_square())];
+ if (pos.side_to_move() == WHITE)
+ result ^= Random64[TurnIdx];
-/// Constructor
+ return result;
+ }
+}
+
+
+/// Book c'tor. Make random number generation less deterministic, for book moves
Book::Book() {
- bookFile = NULL;
- bookSize = 0;
+
+ for (int i = abs(get_system_time() % 10000); i > 0; i--)
+ RKiss.rand<unsigned>();
}
-/// Book::open() opens a book file with a given file name.
+/// Book destructor. Be sure file is closed before we leave.
-void Book::open(const std::string &fName) {
- fileName = fName;
- bookFile = fopen(fileName.c_str(), "rb");
- if(bookFile != NULL) {
- if(fseek(bookFile, 0, SEEK_END) == -1) {
- std::cerr << "Failed to open book file " << fileName << std::endl;
- exit(EXIT_FAILURE);
- }
- bookSize = ftell(bookFile) / 16;
- if(bookSize == -1) {
- std::cerr << "Failed to open book file " << fileName << std::endl;
- exit(EXIT_FAILURE);
- }
- }
+Book::~Book() {
+
+ close();
}
-/// 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 != NULL && fclose(bookFile) == EOF) {
- std::cerr << "Failed to close book file" << std::endl;
- exit(EXIT_FAILURE);
- }
+
+ if (bookFile.is_open())
+ bookFile.close();
+
+ bookName = "";
}
-/// Book::is_open() tests whether a book file has been opened.
+/// Book::open() opens a book file with a given file name
-bool Book::is_open() const {
- return bookFile != NULL && bookSize != 0;
-}
+void Book::open(const string& fileName) {
+ // Close old file before opening the new
+ close();
-/// Book::file_name() returns the file name of the currently active book,
-/// or the empty string if no book is open.
+ bookFile.open(fileName.c_str(), ifstream::in | ifstream::binary);
-const std::string Book::file_name() const {
- return this->is_open()? fileName : "";
-}
-
-
-/// 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);
+ // Silently return when asked to open a non-exsistent file
+ if (!bookFile.is_open())
+ return;
- bestScore += score;
- if(int(genrand_int32() % bestScore) < score)
- bestMove = move;
- }
+ // Get the book size in number of entries
+ bookFile.seekg(0, ios::end);
+ bookSize = long(bookFile.tellg()) / sizeof(BookEntry);
- 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;
- }
+ if (!bookFile.good())
+ {
+ cerr << "Failed to open book file " << fileName << endl;
+ exit(EXIT_FAILURE);
}
- return MOVE_NONE;
+
+ // Set only if successful
+ bookName = fileName;
}
-/// 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.
+/// Book::get_move() gets a book move for a given position. Returns
+/// MOVE_NONE if no book move is found. If findBestMove is true then
+/// return always the highest rated book move.
-int Book::find_key(uint64_t key) const {
- int left, right, mid;
- BookEntry entry;
+Move Book::get_move(const Position& pos, bool findBestMove) {
- // Binary search (finds the leftmost entry)
- left = 0;
- right = bookSize - 1;
+ if (!bookFile.is_open() || bookSize == 0)
+ return MOVE_NONE;
- assert(left <= right);
+ BookEntry entry;
+ int bookMove = MOVE_NONE;
+ unsigned score, scoresSum = 0, bestScore = 0;
+ uint64_t key = book_key(pos);
- while(left < right) {
- mid = (left + right) / 2;
- assert(mid >= left && mid < right);
+ // Choose a book move among the possible moves for the given position
+ for (int idx = find_entry(key); idx < bookSize; idx++)
+ {
+ entry = read_entry(idx);
- this->read_entry(entry, mid);
+ if (entry.key != key)
+ break;
- if(key <= entry.key)
- right = mid;
- else
- left = mid + 1;
- }
+ score = entry.count;
- assert(left == right);
+ if (!findBestMove)
+ {
+ // 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;
+ }
+ else if (score > bestScore)
+ {
+ bestScore = score;
+ bookMove = entry.move;
+ }
+ }
- this->read_entry(entry, left);
+ // 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 12-13-14: promotion piece (from KNIGHT == 1 to QUEEN == 4)
+ //
+ // Castling moves follow "king captures rook" representation. So in case
+ // book move is a promotion we have to convert to our representation, in
+ // all other cases we can directly compare with a Move after having
+ // masked out special Move's flags that are not supported by PolyGlot.
+ int p = (bookMove >> 12) & 7;
+
+ if (p)
+ bookMove = int(make_promotion_move(move_from(Move(bookMove)),
+ move_to(Move(bookMove)), PieceType(p + 1)));
+
+ // Verify the book move (if any) is legal
+ MoveStack mlist[MAX_MOVES];
+ MoveStack* last = generate<MV_LEGAL>(pos, mlist);
+ for (MoveStack* cur = mlist; cur != last; cur++)
+ if ((int(cur->move) & ~(3 << 14)) == bookMove) // Mask out special flags
+ return cur->move;
- return (entry.key == key)? left : bookSize;
+ return MOVE_NONE;
}
-/// 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.
+/// Book::find_entry() 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.
-void Book::read_entry(BookEntry& entry, int n) const {
- assert(n >= 0 && n < bookSize);
- assert(bookFile != NULL);
+int Book::find_entry(uint64_t key) {
- if(fseek(bookFile, n*16, SEEK_SET) == -1) {
- std::cerr << "Failed to read book entry at index " << n << std::endl;
- exit(EXIT_FAILURE);
- }
+ int left, right, mid;
- entry.key = read_integer(bookFile, 8);
- entry.move = read_integer(bookFile, 2);
- entry.count = read_integer(bookFile, 2);
- entry.n = read_integer(bookFile, 2);
- entry.sum = read_integer(bookFile, 2);
-}
+ // Binary search (finds the leftmost entry)
+ left = 0;
+ right = bookSize - 1;
+ assert(left <= right);
-////
-//// Local definitions
-////
+ while (left < right)
+ {
+ mid = (left + right) / 2;
-namespace {
+ assert(mid >= left && mid < right);
- uint64_t book_key(const Position &pos) {
- uint64_t result = 0ULL;
+ if (key <= read_entry(mid).key)
+ right = mid;
+ else
+ left = mid + 1;
+ }
- 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);
+ assert(left == right);
- result ^= book_piece_key(p, s);
- }
- }
+ return read_entry(left).key == key ? left : bookSize;
+}
- result ^= book_castle_key(pos);
- result ^= book_ep_key(pos);
- result ^= book_color_key(pos);
- return result;
- }
-
+/// Book::read_entry() takes an integer index, and returns the BookEntry
+/// at the given index in the book file.
- uint64_t book_piece_key(Piece p, Square s) {
- return Random64[RandomPiece + (PieceTo12[int(p)]^1)*64 + int(s)];
- }
+BookEntry Book::read_entry(int idx) {
+ assert(idx >= 0 && idx < bookSize);
+ assert(bookFile.is_open());
- uint64_t book_castle_key(const Position &pos) {
- uint64_t result = 0ULL;
+ BookEntry e;
- 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;
- }
+ bookFile.seekg(idx * sizeof(BookEntry), ios_base::beg);
-
- uint64_t book_ep_key(const Position &pos) {
- return (pos.ep_square() == SQ_NONE)?
- 0ULL : Random64[RandomEnPassant + square_file(pos.ep_square())];
- }
+ *this >> e.key >> e.move >> e.count >> e.learn;
-
- uint64_t book_color_key(const Position &pos) {
- return (pos.side_to_move() == WHITE)? Random64[RandomTurn] : 0ULL;
- }
-
-
- uint64_t read_integer(FILE *file, int size) {
- uint64_t n = 0ULL;;
- int i;
- int b;
-
- assert(file != NULL);
- assert(size > 0 && size <= 8);
-
- for(i = 0; i < size; i++) {
- b = fgetc(file);
- if(b == EOF) {
- std::cerr << "Failed to read " << size << " bytes from book file"
- << std::endl;
- exit(EXIT_FAILURE);
- }
- assert(b >= 0 && b < 256);
- n = (n << 8) | b;
- }
- return n;
+ if (!bookFile.good())
+ {
+ cerr << "Failed to read book entry at index " << idx << endl;
+ exit(EXIT_FAILURE);
}
-
+ return e;
}
projects / stockfish / blobdiff