public State(State copy)
{
Hash = copy.Hash;
NextState = copy.NextState;
DepthToMate = copy.DepthToMate;
PlayerTurn = copy.PlayerTurn;
Pieces = new byte[] { copy.Pieces[0], copy.Pieces[1], copy.Pieces[2], copy.Pieces[3] };
PieceLocation = new byte[] { copy.PieceLocation[0], copy.PieceLocation[1], copy.PieceLocation[2], copy.PieceLocation[3] };
}
public List<State> CalculateBlack(List<State> stateSet)
{
// find only moves where black MUST move to a state in the stateSet
var newStates = new List<State>();
var b = Board.Create();
foreach (var state in stateSet)
{
var originalHash = state.Hash;
state.PlayerTurn = Board.COLOR_BLACK;
state.Hash = CalcHash(state);
SetupBoard(b, state, Board.COLOR_BLACK);
var moves = GetMovesReverse(b, Board.COLOR_BLACK);
for (int i = 0; i < moves.Length; i++)
{
var from = moves[i][0];
var to = moves[i][1];
// set player to black and set the position to the "precursor" state
state.PlayerTurn = Board.COLOR_BLACK;
MovePieceState(state, to, from);
SetupBoard(b, state, Board.COLOR_BLACK);
b->CurrentMove = 0;
if(AreKingsTouching(b))
{
// revert the state back to the original state
state.PlayerTurn = Board.COLOR_WHITE;
MovePieceState(state, from, to);
continue;
}
// get moves from precursor state to any other available states
var moveBitboard = Moves.GetMoves(b, from);
var movesFromPreviousPos = Bitboard.Bitboard_BitList(moveBitboard);
// We see if there is a way for black to get out of a forced mate by looking
// for any moves that escape it. If white has a forced mate, the input state (original state)
// is supposedly the best move black could make.
// IF black can make moves tho states that aren't already explored, then they lead to a better
// state for black, thus he can escape
bool canEscape = false;
for(int j=0; j < movesFromPreviousPos.Length; j++)
{
var backTo = movesFromPreviousPos[j];
var valid = Board.Make(b, from, backTo);
if (valid)
{
Board.Unmake(b);
// Check if this is a capture. We can't "un-capture" pieces so this would be a way out
// for black.
if (Bitboard.Get(b->Boards[Board.BOARD_WHITE], backTo))
{
canEscape = true;
break;
}
// find the hash for the next possible state
state.PlayerTurn = Board.COLOR_WHITE;
MovePieceState(state, from, backTo);
var nextHash = state.Hash;
state.PlayerTurn = Board.COLOR_BLACK;
MovePieceState(state, backTo, from);
// check if that is a known position
if(!States.ContainsKey(nextHash))
{
canEscape = true;
break;
}
}
}
// If black can not escape the then moving to the original state is the best option black has.
if (!canEscape)
{
var newState = new State(state);
newState.NextState = originalHash;
newState.DepthToMate++;
newStates.Add(newState);
}
// revert the state back to the original state
state.PlayerTurn = Board.COLOR_WHITE;
MovePieceState(state, from, to);
}
// We messed with the state... alot.
// Make sure there isn't a bug in the code and we just corrupted something :)
if (originalHash != state.Hash)
throw new Exception("State was altered");
}
Board.Delete(b);
return newStates;
}
private unsafe void SetupBoard(BoardStruct* b, State state, byte playerTurn)
{
b->Boards[0] = 0;
b->Boards[1] = 0;
b->Boards[2] = 0;
b->Boards[3] = 0;
b->Boards[4] = 0;
b->Boards[5] = 0;
b->Boards[6] = 0;
b->Boards[7] = 0;
b->Castle = 0;
b->EnPassantTile = 0;
b->Hash = 0;
Board.SetPiece(b, state.PieceLocation[0], state.Pieces[0] & 0x0F, state.Pieces[0] & 0xF0);
Board.SetPiece(b, state.PieceLocation[1], state.Pieces[1] & 0x0F, state.Pieces[1] & 0xF0);
Board.SetPiece(b, state.PieceLocation[2], state.Pieces[2] & 0x0F, state.Pieces[2] & 0xF0);
Board.SetPiece(b, state.PieceLocation[3], state.Pieces[3] & 0x0F, state.Pieces[3] & 0xF0);
b->AttacksBlack = Board.AttackMap(b, Board.COLOR_BLACK);
b->AttacksWhite = Board.AttackMap(b, Board.COLOR_WHITE);
b->PlayerTurn = playerTurn;
b->Hash = b->Hash ^ Zob.Keys[Zobrist.ZOBRIST_SIDE, b->PlayerTurn];
Assert(b->Hash == state.Hash, "Hashes do not match");
}
private List<State> Generate4PieceMates(byte[] pieces)
{
var b = Board.Create();
var states = new List<State>();
byte p0 = pieces[0];
byte p1 = pieces[1];
byte p2 = pieces[2];
int i = 0;
for (byte l0 = 0; l0 < 64; l0++)
for (byte l1 = 0; l1 < 64; l1++)
for (byte l2 = 0; l2 < 64; l2++)
for (byte l3 = 0; l3 < 64; l3++)
if (l0 != l1 && l0 != l2 && l0 != l3 && l1 != l2 && l1 != l3 && l2 != l3)
{
var state = new State();
state.Pieces = new byte[4];
state.PieceLocation = new byte[4];
state.PlayerTurn = Board.COLOR_BLACK;
// set pieces
state.Pieces[0] = p0;
state.PieceLocation[0] = l0;
state.Pieces[1] = p1;
state.PieceLocation[1] = l1;
state.Pieces[2] = p2;
state.PieceLocation[2] = l2;
state.Pieces[3] = p2;
state.PieceLocation[3] = l2;
state.DepthToMate = MAX; // set to max
state.Hash = CalcHash(state);
CheckIfMate(state, b);
if (state.DepthToMate != 255)
states.Add(state);
i++;
}
Assert(i == 64 * 63 * 62);
Board.Delete(b);
var mateCount = states.Count(x => x.DepthToMate == 0);
var stalemateCount = states.Count(x => x.DepthToMate == STALEMATE);
return states;
}
/*private bool IsValidState(State state)
{
SetupBoard(bs, state, state.PlayerTurn);
if(AreKingsTouching(bs))
return false;
var oppositePlayer = (state.PlayerTurn == Board.COLOR_WHITE) ? Board.COLOR_BLACK : Board.COLOR_WHITE;
if(Board.IsChecked(bs, oppositePlayer) == 1)
return false;
return true;
}*/
private bool Compare(State state1, State state2)
{
var a = state1.PieceLocation[0] == state2.PieceLocation[0];
var b = state1.PieceLocation[1] == state2.PieceLocation[1];
var c = state1.PieceLocation[2] == state2.PieceLocation[2];
var d = true;
if(state1.Pieces[3] != 0 && state2.Pieces[3] != 0)
d = state1.PieceLocation[3] == state2.PieceLocation[3];
var e = state1.PlayerTurn == state2.PlayerTurn;
return a & b & c & d & e;
}
/// <summary>
/// Calculate hash of position after a move
/// </summary>
/// <param name="state"></param>
/// <param name="moveFrom"></param>
/// <param name="moveTo"></param>
/// <returns></returns>
private ulong CalcHash(State state, byte moveFrom, byte moveTo)
{
if (state.PieceLocation[0] == moveFrom)
state.PieceLocation[0] = moveTo;
if (state.PieceLocation[1] == moveFrom)
state.PieceLocation[1] = moveTo;
if (state.PieceLocation[2] == moveFrom)
state.PieceLocation[2] = moveTo;
if (state.PieceLocation[3] == moveFrom)
state.PieceLocation[3] = moveTo;
var hash = CalcHash(state);
if (state.PieceLocation[0] == moveTo)
state.PieceLocation[0] = moveFrom;
if (state.PieceLocation[1] == moveTo)
state.PieceLocation[1] = moveFrom;
if (state.PieceLocation[2] == moveTo)
state.PieceLocation[2] = moveFrom;
if (state.PieceLocation[3] == moveTo)
state.PieceLocation[3] = moveFrom;
return hash;
}
private ulong CalcHash(State state)
{
ulong hash = 0;
hash ^= Zob.Keys[Zob.Index[state.Pieces[0]], state.PieceLocation[0]];
hash ^= Zob.Keys[Zob.Index[state.Pieces[1]], state.PieceLocation[1]];
hash ^= Zob.Keys[Zob.Index[state.Pieces[2]], state.PieceLocation[2]];
if(state.Pieces[3] != 0)
hash ^= Zob.Keys[Zob.Index[state.Pieces[3]], state.PieceLocation[3]];
hash ^= Zob.Keys[Zobrist.ZOBRIST_SIDE, state.PlayerTurn];
return hash;
}
public bool QueryStates(byte[] pieces)
{
Console.Write("Query Position (wK, wQ, bK):");
var line = Console.ReadLine();
if (line == "quit" || line == "exit")
return false;
var locations = line.Split(',').Select(x => Convert.ToByte(x.Trim())).ToArray();
var stateTemp = new State();
stateTemp.PieceLocation = locations;
stateTemp.Pieces = pieces;
stateTemp.PlayerTurn = Board.COLOR_WHITE;
var hash = CalcHash(stateTemp);
State state = null;
if (States.ContainsKey(hash))
state = States[hash];
Console.WriteLine("Hash: " + state.Hash);
Console.WriteLine("Depth to Mate: " + state.DepthToMate);
Console.WriteLine("Position: " + state.PieceLocation[0] + ", " + state.PieceLocation[1] + ", " + state.PieceLocation[2] + ", " + state.PieceLocation[3]);
if (States.ContainsKey(state.NextState))
{
var next = States[state.NextState];
Console.WriteLine("Next Position: " + next.PieceLocation[0] + ", " + next.PieceLocation[1] + ", " + next.PieceLocation[2] + ", " + next.PieceLocation[3]);
}
Console.WriteLine("");
return true;
}
public void MovePieceState(State state, byte moveFrom, byte moveTo)
{
if (state.PieceLocation[0] == moveFrom)
state.PieceLocation[0] = moveTo;
if (state.PieceLocation[1] == moveFrom)
state.PieceLocation[1] = moveTo;
if (state.PieceLocation[2] == moveFrom)
state.PieceLocation[2] = moveTo;
if (state.PieceLocation[3] == moveFrom)
state.PieceLocation[3] = moveTo;
state.Hash = CalcHash(state);
}
public byte[] GetMove(State a, State b)
{
if (a.PieceLocation[0] != b.PieceLocation[0])
return new byte[] { a.PieceLocation[0], b.PieceLocation[0] };
if (a.PieceLocation[1] != b.PieceLocation[1])
return new byte[] { a.PieceLocation[1], b.PieceLocation[1] };
if (a.PieceLocation[2] != b.PieceLocation[2])
return new byte[] { a.PieceLocation[2], b.PieceLocation[2] };
if (a.PieceLocation[3] != b.PieceLocation[3])
return new byte[] { a.PieceLocation[3], b.PieceLocation[3] };
return new byte[2]; // no move
}
/// <summary>
/// Checks a position and determines if black is mated
/// </summary>
/// <param name="state"></param>
/// <param name="b"></param>
public void CheckIfMate(State state, BoardStruct* b)
{
SetupBoard(b, state, Board.COLOR_BLACK);
var from = state.PieceLocation[2];
var moveBoard = Moves.GetMoves(b, from);
var moves = Bitboard.Bitboard_BitList(moveBoard);
// make sure the black king can't directly attack the white king, that's an illegal position
if (AreKingsTouching(b))
return;
bool isMate = true;
for (int j = 0; j < moves.Length; j++)
{
var valid = Board.Make(b, from, moves[j]);
if (valid)
{
Board.Unmake(b);
isMate = false;
break;
}
}
if (isMate)
{
if (Board.IsChecked(b, Board.COLOR_BLACK) == 1)
state.DepthToMate = 0;
else
state.DepthToMate = STALEMATE;
}
}
public List<State> CalculateWhite(List<State> stateSet)
{
// find all states where white can transition from a state into one of the input states in stateSet
var newStates = new List<State>();
var b = Board.Create();
foreach(var state in stateSet)
{
var originalHash = state.Hash;
state.PlayerTurn = Board.COLOR_WHITE;
state.Hash = CalcHash(state);
SetupBoard(b, state, Board.COLOR_WHITE);
var moves = GetMovesReverse(b, Board.COLOR_WHITE);
for (int i = 0; i < moves.Length; i++)
{
var from = moves[i][0];
var to = moves[i][1];
// set player to white and set the position to the "precursor" state
state.PlayerTurn = Board.COLOR_WHITE;
MovePieceState(state, to, from);
SetupBoard(b, state, Board.COLOR_WHITE);
b->CurrentMove = 0;
// we must see the the position we are moving from already had black in check
// Such a position could never actually occur, since can't enter check by himself
bool wasChecked = Board.IsChecked(b, Board.COLOR_BLACK) == 1;
if (!wasChecked)
{
var valid = Board.Make(b, from, to);
if (valid)
{
var newState = new State(state);
newState.NextState = originalHash;
newState.DepthToMate++;
newStates.Add(newState);
}
}
// revert the state back to the original state
state.PlayerTurn = Board.COLOR_BLACK;
MovePieceState(state, from, to);
}
if (originalHash != state.Hash)
throw new Exception("State was altered");
}
Board.Delete(b);
return newStates;
}
