engine.cpp

Siemens 的SIMpad是一个多媒体设备

/* Yo Emacs, this -*- C++ -*-
 *******************************************************************
 *******************************************************************
 *
 *
 * KREVERSI
 *
 *
 *******************************************************************
 *
 * A Reversi (or sometimes called Othello) game
 *
 *******************************************************************
 *
 * Created 1997 by Mario Weilguni <[e-mail]>. This file 
 * is ported from Mats Luthman's <[e-mail]> JAVA applet. 
 * Many thanks to Mr. Luthman who has allowed me to put this port 
 * under the GNU GPL. Without his wonderful game engine kreversi 
 * would be just another of those Reversi programs a five year old 
 * child could beat easily. But with it it's a worthy opponent!
 *
 * If you are interested on the JAVA applet of Mr. Luthman take a
 * look at http://www.sylog.se/~mats/
 *
 *******************************************************************
 *
 * This file is part of the KDE project "KREVERSI"
 *
 * KREVERSI 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 2, or (at your option)
 * any later version.
 *
 * KREVERSI 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 KREVERSI; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 *******************************************************************
 */

// The class Engine produces moves from a Game object through calls to the
// function ComputeMove().
//
// First of all: this is meant to be a simple example of a game playing
// program. Not everything is done in the most clever way, particularly not
// the way the moves are searched, but it is hopefully made in a way that makes
// it easy to understand. The function ComputeMove2() that does all the work
// is actually not much more than a hundred lines. Much could be done to
// make the search faster though, I'm perfectly aware of that. Feel free
// to experiment.
//
// The method used to generate the moves is called minimax tree search with
// alpha-beta pruning to a fixed depth. In short this means that all possible
// moves a predefined number of moves ahead are either searched or refuted
// with a method called alpha-beta pruning. A more thorough explanation of
// this method could be found at the world wide web at http:
// //yoda.cis.temple.edu:8080/UGAIWWW/lectures96/search/minimax/alpha-beta.html
// at the time this was written. Searching for "minimax" would also point
// you to information on this subject. It is probably possible to understand
// this method by reading the source code though, it is not that complicated.
//
// At every leaf node at the search tree, the resulting position is evaluated.
// Two things are considered when evaluating a position: the number of pieces
// of each color and at which squares the pieces are located. Pieces at the
// corners are valuable and give a high value, and having pieces at squares
// next to a corner is not very good and they give a lower value. In the
// beginning of a game it is more important to have pieces on "good" squares,
// but towards the end the total number of pieces of each color is given a
// higher weight. Other things, like how many legal moves that can be made in a
// position, and the number of pieces that can never be turned would probably
// make the program stronger if they were considered in evaluating a position,
// but that would make things more complicated (this was meant to be very
// simple example) and would also slow down computation (considerably?).
//
// The member m_board[10][10]) holds the current position during the
// computation. It is initiated at the start of ComputeMove() and
// every move that is made during the search is made on this board. It should
// be noted that 1 to 8 is used for the actual board, but 0 and 9 can be
// used too (they are always empty). This is practical when turning pieces
// when moves are made on the board. Every piece that is put on the board
// or turned is saved in the stack m_squarestack (see class SquareStack) so
// every move can easily be reversed after the search in a node is completed.
//
// The member m_bc_board[][] holds board control values for each square
// and is initiated by a call to the function private void SetupBcBoard()
// from Engines constructor. It is used in evaluation of positions except
// when the game tree is searched all the way to the end of the game.
//
// The two members m_coord_bit[9][9] and m_neighbor_bits[9][9] are used to
// speed up the tree search. This goes against the principle of keeping things
// simple, but to understand the program you do not need to understand them
// at all. They are there to make it possible to throw away moves where
// the piece that is played is not adjacent to a piece of opposite color
// at an early stage (because they could never be legal). It should be
// pointed out that not all moves that pass this test are legal, there will
// just be fewer moves that have to be tested in a more time consuming way.
//
// There are also two other members that should be mentioned: Score m_score
// and Score m_bc_score. They hold the number of pieces of each color and
// the sum of the board control values for each color during the search
// (this is faster than counting at every leaf node).
//

// The classes SquareStackEntry and SquareStack implement a
// stack that is used by Engine to store pieces that are turned during
// searching (see ComputeMove()).
//
// The class MoveAndValue is used by Engine to store all possible moves
// at the first level and the values that were calculated for them.
// This makes it possible to select a random move among those with equal
// or nearly equal value after the search is completed.


#include "Engine.h"
#include <stdlib.h>

const int Engine::LARGEINT = 99999;
const int Engine::ILLEGAL_VALUE = 8888888;
const int Engine::BC_WEIGHT = 3;

inline void SquareStackEntry::setXY(int x, int y) { 
  m_x = x; 
  m_y = y; 
}

#if !defined(__GNUC__)

ULONG64::ULONG64() : QBitArray(64) {
  fill(0);
}

ULONG64::ULONG64( unsigned int value ) : QBitArray(64) {
  fill(0);
  for(int i = 0; i < 32; i++) {
    setBit(i, (bool)(value & 1));
    value >>= 1;
  }
}

void ULONG64::shl() {
  for(int i = 63; i > 0; i--)
    setBit(i, testBit(i-1));
  setBit(0, 0);
}

#endif


SquareStackEntry::SquareStackEntry() { 
  setXY(0,0); 
}


SquareStack::SquareStack() {
  init(0);
}


SquareStack::SquareStack(int size) {
  init(size);
}


void SquareStack::resize(int size) {
  m_squarestack.resize(size);
}


void SquareStack::init(int size) { 
  resize(size); 
  m_top = 0;     
  for (int i=0; i<size; i++) 
    m_squarestack[i].setXY(0,0);
}


inline SquareStackEntry SquareStack::Pop() { 
  return m_squarestack[--m_top]; 
}


inline void SquareStack::Push(int x, int y) {
  m_squarestack[m_top].m_x = x;
  m_squarestack[m_top++].m_y = y;
}


inline void MoveAndValue::setXYV(int x, int y, int value) {
  m_x = x;
  m_y = y;
  m_value = value;
}


MoveAndValue::MoveAndValue() {
  setXYV(0,0,0);
}


MoveAndValue::MoveAndValue(int x, int y, int value) {
  setXYV(x, y, value);
}


Engine::Engine(int st, int sd) : SuperEngine(st, sd) {
  SetupBcBoard(); 
  SetupBits(); 
}


Engine::Engine(int st) : SuperEngine(st) { 
  SetupBcBoard(); 
  SetupBits(); 
}


Engine::Engine() : SuperEngine(5) { 
  SetupBcBoard(); 
  SetupBits(); 
}


// keep GUI alive
void Engine::yield() {
  //qApp->processEvents();
}


Move Engine::ComputeMove(Game g) {
  m_exhaustive = false;

  int player = g.GetWhoseTurn();

  if (player == Score::NOBODY) 
    return Move(-1,-1,-1);

  m_score.InitScore(g.GetScore(Score::WHITE), g.GetScore(Score::BLACK));
  if (m_score.GetScore(Score::WHITE) + m_score.GetScore(Score::BLACK) == 4)
    return ComputeFirstMove(g);

  // JAVA m_board = new int[10][10];
  m_squarestack = SquareStack(3000); // More than enough...
  m_squarestack.init(3000);
  m_depth = m_strength;

  if (m_score.GetScore(Score::WHITE) + m_score.GetScore(Score::BLACK) +
      m_depth + 4 >= 64)
    m_depth =
      64 - m_score.GetScore(Score::WHITE) - m_score.GetScore(Score::BLACK);
  else if (m_score.GetScore(Score::WHITE) + m_score.GetScore(Score::BLACK) +
	   m_depth + 7 >= 64)
    m_depth += 3;
  else if (m_score.GetScore(Score::WHITE) + m_score.GetScore(Score::BLACK) +
	   m_depth + 9 >= 64)
    m_depth += 2;
  else if (m_score.GetScore(Score::WHITE) + m_score.GetScore(Score::BLACK) +
	   m_depth + 11 >= 64)
    m_depth++;

  if (m_score.GetScore(Score::WHITE) + m_score.GetScore(Score::BLACK) +
      m_depth >= 64) m_exhaustive = true;

  m_coeff =
    100 - (100*
	   (m_score.GetScore(Score::WHITE) + m_score.GetScore(Score::BLACK) +
	    m_depth - 4))/60;

  m_nodes_searched = 0;

  for (int x=0; x<10; x++)
    for (int y=0; y<10; y++)
      m_board[x][y] = Score::NOBODY;

  for (int x=1; x<9; x++)
    for (int y=1; y<9; y++)
      m_board[x][y] = g.GetSquare(x, y);

  m_bc_score.InitScore(CalcBcScore(Score::WHITE), CalcBcScore(Score::BLACK));

  ULONG64 playerbits = ComputeOccupiedBits(player);
  ULONG64 opponentbits = ComputeOccupiedBits(Score::GetOpponent(player));

  int maxval = -LARGEINT;
  int max_x = 0;
  int max_y = 0;

  MoveAndValue moves[60];
  int number_of_moves = 0;
  int number_of_maxval = 0;

  SetInterrupt(false);

  ULONG64 null_bits;
  null_bits = 0;

  //struct tms tmsdummy; 
  //long starttime = times(&tmsdummy);

  for (int x=1; x<9; x++)
    for (int y=1; y<9; y++)
      if (m_board[x][y] == Score::NOBODY &&
	  (m_neighbor_bits[x][y] & opponentbits) != null_bits)
	{

	  int val = ComputeMove2(x, y, player, 1, maxval, 
				 playerbits, opponentbits);

	  if (val != ILLEGAL_VALUE)
	    {
	      moves[number_of_moves++].setXYV(x, y, val);