/*
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) 2008-2012 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 <iostream>
#include "book.h"
-#include "mersenne.h"
+#include "misc.h"
#include "movegen.h"
-
-////
-//// Global variables
-////
-
-Book OpeningBook;
-
-
-////
-//// Local definitions
-////
+using namespace std;
namespace {
- /// Random numbers from PolyGlot, used to compute book hash keys.
-
- const uint64_t Random64[781] = {
+ // Random numbers from PolyGlot, used to compute book hash keys
+ const Key PolyGlotRandoms[781] = {
0x9D39247E33776D41ULL, 0x2AF7398005AAA5C7ULL, 0x44DB015024623547ULL,
0x9C15F73E62A76AE2ULL, 0x75834465489C0C89ULL, 0x3290AC3A203001BFULL,
0x0FBBAD1F61042279ULL, 0xE83A908FF2FB60CAULL, 0x0D7E765D58755C10ULL,
0xF8D626AAAF278509ULL
};
+ // Offsets to the PolyGlotRandoms[] array of zobrist keys
+ const Key* ZobPiece = PolyGlotRandoms + 0;
+ const Key* ZobCastle = PolyGlotRandoms + 768;
+ const Key* ZobEnPassant = PolyGlotRandoms + 772;
+ const Key* ZobTurn = PolyGlotRandoms + 780;
- /// 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
- };
-
-
- /// 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);
-}
+ // book_key() returns the PolyGlot hash key of the given position
+ uint64_t book_key(const Position& pos) {
+ uint64_t key = 0;
+ Bitboard b = pos.pieces();
-////
-//// Functions
-////
-
-
-/// Constructor
-
-Book::Book() : bookSize(0) {}
-
+ while (b)
+ {
+ // Piece offset is at 64 * polyPiece where polyPiece is defined as:
+ // BP = 0, WP = 1, BN = 2, WN = 3, ... BK = 10, WK = 11
+ Square s = pop_1st_bit(&b);
+ Piece p = pos.piece_on(s);
+ int polyPiece = 2 * (type_of(p) - 1) + (color_of(p) == WHITE);
+ key ^= ZobPiece[64 * polyPiece + s];
+ }
-/// Book::open() opens a book file with a given file name.
+ b = pos.can_castle(ALL_CASTLES);
-void Book::open(const std::string &fName) {
+ while (b)
+ key ^= ZobCastle[pop_1st_bit(&b)];
- fileName = fName;
- bookFile.open(fileName.c_str(), std::ifstream::in | std::ifstream::binary);
- if (!bookFile.is_open())
- return;
+ if (pos.ep_square() != SQ_NONE)
+ key ^= ZobEnPassant[file_of(pos.ep_square())];
- bookFile.seekg(0, std::ios::end);
- bookSize = bookFile.tellg() / 16;
- bookFile.seekg(0, std::ios::beg);
+ if (pos.side_to_move() == WHITE)
+ key ^= ZobTurn[0];
- if (!bookFile.good())
- {
- std::cerr << "Failed to open book file " << fileName << std::endl;
- exit(EXIT_FAILURE);
+ return key;
}
-}
+} // namespace
-/// Book::close() closes the currently open book file.
+Book::Book() : size(0) {
-void Book::close() {
-
- if (bookFile.is_open())
- bookFile.close();
+ for (int i = Time::current_time().msec() % 10000; i > 0; i--)
+ RKiss.rand<unsigned>(); // Make random number generation less deterministic
}
+Book::~Book() { if (is_open()) close(); }
-/// Book::is_open() tests whether a book file has been opened.
-
-bool Book::is_open() const {
-
- return bookFile.is_open() && bookSize != 0;
-}
+/// Book::operator>>() reads sizeof(T) chars from the file's binary byte stream
+/// and converts them in a number of type T. A Polyglot book stores numbers in
+/// big-endian format.
-/// Book::file_name() returns the file name of the currently active book,
-/// or the empty string if no book is open.
+template<typename T> Book& Book::operator>>(T& n) {
-const std::string Book::file_name() const {
+ n = 0;
+ for (size_t i = 0; i < sizeof(T); i++)
+ n = T((n << 8) + ifstream::get());
- return bookFile.is_open() ? fileName : "";
+ return *this;
}
-
-/// 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);
-
- bestScore += score;
- if(int(genrand_int32() % bestScore) < score)
- bestMove = move;
- }
-
- 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;
- }
- }
- return MOVE_NONE;
+template<> Book& Book::operator>>(BookEntry& e) {
+ return *this >> e.key >> e.move >> e.count >> e.learn;
}
-/// 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::open() tries to open a book file with the given name after closing
+/// any exsisting one.
-int Book::find_key(uint64_t key) const {
- int left, right, mid;
- BookEntry entry;
+bool Book::open(const char* fName) {
- // Binary search (finds the leftmost entry)
- left = 0;
- right = bookSize - 1;
+ fileName = "";
- assert(left <= right);
+ if (is_open()) // Cannot close an already closed file
+ close();
- while(left < right) {
- mid = (left + right) / 2;
- assert(mid >= left && mid < right);
+ ifstream::open(fName, ifstream::in | ifstream::binary | ios::ate);
- this->read_entry(entry, mid);
-
- if(key <= entry.key)
- right = mid;
- else
- left = mid + 1;
+ if (!is_open())
+ {
+ clear();
+ return false; // Silently fail if the file is not found
}
- assert(left == right);
-
- this->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 n) const {
-
- assert(n >= 0 && n < bookSize);
- assert(bookFile.is_open());
+ // Get the book size in number of entries, we are already at the end of file
+ size = (size_t)tellg() / sizeof(BookEntry);
- bookFile.seekg(n*16, std::ios_base::beg);
- if (!bookFile.good())
+ if (!good())
{
- std::cerr << "Failed to read book entry at index " << n << std::endl;
- exit(EXIT_FAILURE);
+ cerr << "Failed to open book file " << fName << endl;
+ exit(EXIT_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);
+
+ fileName = fName; // Set only if successful
+ return true;
}
-////
-//// Local definitions
-////
+/// Book::probe() tries to find a book move for the given position. If no move
+/// is found returns MOVE_NONE. If pickBest is true returns always the highest
+/// rated move, otherwise randomly chooses one, based on the move score.
-namespace {
+Move Book::probe(const Position& pos, const string& fName, bool pickBest) {
- 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);
- }
- }
+ BookEntry e;
+ uint16_t best = 0;
+ unsigned sum = 0;
+ Move move = MOVE_NONE;
+ uint64_t key = book_key(pos);
- result ^= book_castle_key(pos);
- result ^= book_ep_key(pos);
- result ^= book_color_key(pos);
-
- return result;
- }
+ if (fileName != fName && !open(fName.c_str()))
+ return MOVE_NONE;
+ binary_search(key);
- uint64_t book_piece_key(Piece p, Square s) {
- return Random64[RandomPiece + (PieceTo12[int(p)]^1)*64 + int(s)];
+ while (*this >> e, e.key == key && good())
+ {
+ 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 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)
+ || (pickBest && e.count == best))
+ move = Move(e.move);
}
+ if (!move)
+ return MOVE_NONE;
+
+ // 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 "king captures rook" representation. So in case book
+ // move is a promotion we have to convert to our representation, in all the
+ // other cases we can directly compare with a Move after having masked out
+ // the special Move's 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<MV_LEGAL> ml(pos); !ml.end(); ++ml)
+ if (move == (ml.move() & 0x3FFF))
+ return ml.move();
- 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;
- }
+ return MOVE_NONE;
+}
- uint64_t book_ep_key(const Position &pos) {
- return (pos.ep_square() == SQ_NONE)?
- 0ULL : Random64[RandomEnPassant + square_file(pos.ep_square())];
- }
+/// Book::binary_search() takes a book key as input, and does a binary search
+/// through the book file for the given key. File stream current position is set
+/// to the leftmost book entry with the same key as the input.
+void Book::binary_search(uint64_t key) {
- uint64_t book_color_key(const Position &pos) {
- return (pos.side_to_move() == WHITE)? Random64[RandomTurn] : 0ULL;
- }
+ size_t low, high, mid;
+ BookEntry e;
+ low = 0;
+ high = size - 1;
- uint16_t read_integer16(std::ifstream& file) {
+ assert(low <= high);
- uint64_t n = read_integer(file, 2);
- assert(n == (uint16_t)n);
- return (uint16_t)n;
- }
+ while (low < high && good())
+ {
+ mid = (low + high) / 2;
+ assert(mid >= low && mid < high);
- uint64_t read_integer64(std::ifstream& file) {
+ seekg(mid * sizeof(BookEntry), ios_base::beg);
+ *this >> e;
- return read_integer(file, 8);
+ if (key <= e.key)
+ high = mid;
+ else
+ low = mid + 1;
}
+ assert(low == high);
- uint64_t read_integer(std::ifstream& file, int size) {
-
- char buf[8];
- file.read(buf, size);
-
- 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;
- }
+ seekg(low * sizeof(BookEntry), ios_base::beg);
}
projects / stockfish / blobdiff