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Big book.cpp cleanup

Browse source 
Better document PolyGlot formats and greatly
reduce line count.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-01-10 09:41:26 +01:00
parent d84ffc0cfa
commit 611a29f767
3 changed files with 98 additions and 185 deletions
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225
src/book.cpp
View file

@ -24,11 +24,6 @@
Public License, and can be downloaded from http://wbec-ridderkerk.nl
*/
////
//// Includes
////
#include <cassert>
#include <iostream>
@ -37,15 +32,8 @@
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
const uint64_t Random64[781] = {
0x9D39247E33776D41ULL, 0x2AF7398005AAA5C7ULL, 0x44DB015024623547ULL,
@ -317,20 +305,48 @@ namespace {
const int EnPassantIdx = 772;
const int TurnIdx = 780;
// Local functions
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);
// book_key() builds up a PolyGlot hash key out of a position
uint64_t book_key(const Position& pos) {
// 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();
while (b)
{
Square s = pop_1st_bit(&b);
int p = PieceToPoly[int(pos.piece_on(s))];
result ^= Random64[PieceIdx + 64 * p + int(s)];
}
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];
if (pos.ep_square() != SQ_NONE)
result ^= Random64[EnPassantIdx + square_file(pos.ep_square())];
if (pos.side_to_move() == WHITE)
result ^= Random64[TurnIdx];
return result;
}
}
////
//// Functions
////
// C'tor. Make random number generation less deterministic, for book moves
/// Book c'tor. Make random number generation less deterministic, for book moves
Book::Book() {
for (int i = abs(get_system_time() % 10000); i > 0; i--)
@ -338,7 +354,7 @@ Book::Book() {
}
/// Destructor. Be sure file is closed before we leave.
/// Book destructor. Be sure file is closed before we leave.
Book::~Book() {
@ -353,17 +369,18 @@ void Book::close() {
if (is_open())
ifstream::close();
bookName = "";
}
/// Book::open() opens a book file with a given file name
void Book::open(const string& fName) {
void Book::open(const string& fileName) {
// Close old file before opening the new
close();
fileName = fName;
ifstream::open(fileName.c_str(), ifstream::in | ifstream::binary);
// Silently return when asked to open a non-exsistent file
@ -372,28 +389,22 @@ void Book::open(const string& fName) {
// Get the book size in number of entries
seekg(0, ios::end);
bookSize = long(tellg()) / EntrySize;
seekg(0, ios::beg);
bookSize = long(tellg()) / sizeof(BookEntry);
if (!good())
{
cerr << "Failed to open book file " << fileName << endl;
exit(EXIT_FAILURE);
}
}
/// Book::file_name() returns the file name of the currently active book,
/// or the empty string if no book is open.
const string Book::file_name() { // Not const to compile on HP-UX 11.X
return is_open() ? fileName : "";
// Set only if successful
bookName = fileName;
}
/// Book::get_move() gets a book move for a given position. Returns
/// MOVE_NONE if no book move is found.
/// MOVE_NONE if no book move is found. If findBestMove is true then
/// return always the highest rated book move.
Move Book::get_move(const Position& pos, bool findBestMove) {
@ -402,29 +413,21 @@ Move Book::get_move(const Position& pos, bool findBestMove) {
BookEntry entry;
int bookMove = MOVE_NONE;
unsigned scoresSum = 0, bestScore = 0;
unsigned score, scoresSum = 0, bestScore = 0;
uint64_t key = book_key(pos);
// Choose a book move among the possible moves for the given position
for (int idx = find_key(key); idx < bookSize; idx++)
for (int idx = find_entry(key); idx < bookSize; idx++)
{
read_entry(entry, idx);
entry = read_entry(idx);
if (entry.key != key)
break;
unsigned score = entry.count;
score = entry.count;
// If findBestMove is true choose highest rated book move
if (findBestMove)
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.
@ -432,8 +435,12 @@ Move Book::get_move(const Position& pos, bool findBestMove) {
if (RKiss.rand<unsigned>() % scoresSum < score)
bookMove = entry.move;
}
if (!bookMove)
return MOVE_NONE;
else if (score > bestScore)
{
bestScore = score;
bookMove = entry.move;
}
}
// A PolyGlot book move is encoded as follows:
//
@ -451,7 +458,7 @@ Move Book::get_move(const Position& pos, bool findBestMove) {
bookMove = int(make_promotion_move(move_from(Move(bookMove)),
move_to(Move(bookMove)), PieceType(p + 1)));
// Verify the book move is legal
// Verify the book move (if any) is legal
MoveStack mlist[MOVES_MAX];
MoveStack* last = generate<MV_LEGAL>(pos, mlist);
for (MoveStack* cur = mlist; cur != last; cur++)
@ -462,15 +469,14 @@ Move Book::get_move(const Position& pos, bool findBestMove) {
}
/// Book::find_key() takes a book key as input, and does a binary search
/// 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.
int Book::find_key(uint64_t key) {
int Book::find_entry(uint64_t key) {
int left, right, mid;
BookEntry entry;
// Binary search (finds the leftmost entry)
left = 0;
@ -484,9 +490,7 @@ int Book::find_key(uint64_t key) {
assert(mid >= left && mid < right);
read_entry(entry, mid);
if (key <= entry.key)
if (key <= read_entry(mid).key)
right = mid;
else
left = mid + 1;
@ -494,111 +498,28 @@ int Book::find_key(uint64_t key) {
assert(left == right);
read_entry(entry, left);
return entry.key == key ? left : bookSize;
return read_entry(left).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.
/// Book::read_entry() takes an integer index, and returns the BookEntry
/// at the given index in the book file.
void Book::read_entry(BookEntry& entry, int idx) {
BookEntry Book::read_entry(int idx) {
assert(idx >= 0 && idx < bookSize);
assert(is_open());
seekg(idx * EntrySize, ios_base::beg);
BookEntry e;
*this >> entry;
seekg(idx * sizeof(BookEntry), ios_base::beg);
*this >> e.key >> e.move >> e.count >> e.learn;
if (!good())
{
cerr << "Failed to read book entry at index " << idx << endl;
exit(EXIT_FAILURE);
}
}
/// 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];
uint64_t n = 0;
read(buf, size);
// Numbers are stored on disk as a binary byte stream
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;
Bitboard b = pos.occupied_squares();
while (b)
{
Square s = pop_1st_bit(&b);
result ^= book_piece_key(pos.piece_on(s), 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[PieceIdx + (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[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];
return result;
}
uint64_t book_ep_key(const Position& pos) {
return pos.ep_square() == SQ_NONE ? 0 : Random64[EnPassantIdx + square_file(pos.ep_square())];
}
uint64_t book_color_key(const Position& pos) {
return pos.side_to_move() == WHITE ? Random64[TurnIdx] : 0;
}
return e;
}

48
src/book.h
View file

@ -17,22 +17,9 @@
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
Public License, and can be downloaded from http://wbec-ridderkerk.nl
*/
#if !defined(BOOK_H_INCLUDED)
#define BOOK_H_INCLUDED
////
//// Includes
////
#include <fstream>
#include <string>
@ -41,16 +28,14 @@
#include "rkiss.h"
////
//// Types
////
// A Polyglot book is a series of "entries" of 16 bytes. All integers are
// stored highest byte first (regardless of size). The entries are ordered
// according to key. Lowest key first.
struct BookEntry {
uint64_t key;
uint16_t move;
uint16_t count;
uint16_t n;
uint16_t sum;
uint32_t learn;
};
class Book : private std::ifstream {
@ -59,23 +44,30 @@ class Book : private std::ifstream {
public:
Book();
~Book();
void open(const std::string& fName);
void open(const std::string& fileName);
void close();
const std::string file_name();
Move get_move(const Position& pos, bool findBestMove);
const std::string name() const { return bookName; }
private:
Book& operator>>(uint64_t& n) { n = read_integer(8); return *this; }
Book& operator>>(uint16_t& n) { n = (uint16_t)read_integer(2); return *this; }
void operator>>(BookEntry& e) { *this >> e.key >> e.move >> e.count >> e.n >> e.sum; }
// read n chars from the file stream and converts them in an
// integer number. Integers are stored with highest byte first.
template<int n> uint64_t get_int();
uint64_t read_integer(int size);
void read_entry(BookEntry& e, int n);
int find_key(uint64_t key);
template<typename T>
Book& operator>>(T& n) { n = (T)get_int<sizeof(T)>(); return *this; }
std::string fileName;
BookEntry read_entry(int idx);
int find_entry(uint64_t key);
std::string bookName;
int bookSize;
RKISS RKiss;
};
// Yes, we indulge a bit here ;-)
template<int n> inline uint64_t Book::get_int() { return 256 * get_int<n-1>() + get(); }
template<> inline uint64_t Book::get_int<1>() { return get(); }
#endif // !defined(BOOK_H_INCLUDED)

2
src/search.cpp
View file

@ -423,7 +423,7 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[
// Look for a book move, only during games, not tests
if (UseTimeManagement && Options["OwnBook"].value<bool>())
{
if (Options["Book File"].value<std::string>() != OpeningBook.file_name())
if (Options["Book File"].value<std::string>() != OpeningBook.name())
OpeningBook.open(Options["Book File"].value<std::string>());
Move bookMove = OpeningBook.get_move(pos, Options["Best Book Move"].value<bool>());