int IsPathClear(enum ChessPiece board[8][8], int oldx, int oldy, int newx, int newy)
{
int dx = (newx == oldx) ? 0 : ((newx > oldx) ? 1 : -1);
int dy = (newy == oldy) ? 0 : ((newy > oldy) ? 1 : -1);
int x = oldx;
int y = oldy;
/* straight lines and diagonals only */
if ((abs(oldx - newx) != abs(oldy - newy)) && (oldx != newx) && (oldy != newy))
{
return 0;
}
while ((x != newx) || (y != newy))
{
x += dx;
y += dy;
if (board[x][y] != CP_EMPTY && !((x == newx) && (y == newy) && (IsPieceWhite(board[newx][newy]) != IsPieceWhite(board[oldx][oldy]))))
{
return 0;
}
}
return 1;
}
int getCenterControlScore(ChessBoard * board, bool white) {
int whiteCenterScore = 0;
int blackCenterScore = 0;
BITBOARD iterateCenterSquares = centerSquares;
while(iterateCenterSquares != 0) {
short centerSquare = FirstOne(iterateCenterSquares);
iterateCenterSquares ^= offset_to_mask(centerSquare);
BITBOARD attackBitboard = get_attacksto_bitboard(board, centerSquare);
short whiteAttacks = NumOnes(attackBitboard & board->whitePieces);
short blackAttacks = NumOnes(attackBitboard & board->blackPieces);
short contents = board->boardContents[centerSquare];
if (contents != EMPTY) {
if (IsPieceWhite(contents))
whiteAttacks += 2;
else
blackAttacks += 2;
}
whiteCenterScore += whiteAttacks * EvalParameters::whiteCenterControlScale[centerSquare];
blackCenterScore += blackAttacks * EvalParameters::blackCenterControlScale[centerSquare];
}
if (white)
return whiteCenterScore - blackCenterScore;
else
return blackCenterScore - whiteCenterScore;
}
int IsMoveLegal(enum ChessPiece board[8][8], int oldx, int oldy, int newx, int newy, enum ChessCastling *castling, char **enpassanttarget)
{
enum ChessPiece tempboard[8][8];
char *letters = "abcdefgh";
char *numbers = "87654321";
char move[5];
int iswhitemove = IsPieceWhite(board[oldx][oldy]);
if (CanPieceMoveHere(board, oldx, oldy, newx, newy, castling, enpassanttarget))
{
/* is this a castling move? Then check the intermediate square */
if (oldx == 4 && oldy == 7 && newy == 7 && (newx == 6 || newx == 2) && board[oldx][oldy] == CP_WKING)
{
CopyBoard(board, tempboard);
if (newx == 6)
{
strcpy(move, "e8f8");
ExecuteMove(tempboard, move, 0, NULL, NULL);
if (!IsPositionLegal(tempboard, !iswhitemove))
{
return 0;
}
}
if (newx == 2)
{
strcpy(move, "e8d8");
ExecuteMove(tempboard, move, 0, NULL, NULL);
if (!IsPositionLegal(tempboard, !iswhitemove))
{
return 0;
}
}
}
if (oldx == 4 && oldy == 7 && newy == 0 && (newx == 6 || newx == 2) && board[oldx][oldy] == CP_BKING)
{
CopyBoard(board, tempboard);
if (newx == 6)
{
strcpy(move, "e1f1");
ExecuteMove(tempboard, move, 0, NULL, NULL);
if (!IsPositionLegal(tempboard, !iswhitemove))
{
return 0;
}
}
if (newx == 2)
{
strcpy(move, "e1d1");
ExecuteMove(tempboard, move, 0, NULL, NULL);
if (!IsPositionLegal(tempboard, !iswhitemove))
{
return 0;
}
}
}
CopyBoard(board, tempboard);
move[0] = letters[oldx];
move[1] = numbers[oldy];
move[2] = letters[newx];
move[3] = numbers[newy];
move[4] = '\0';
ExecuteMove(tempboard, move, 0, NULL, NULL);
return IsPositionLegal(tempboard, !iswhitemove);
}
return 0;
}
int CanPieceMoveHere(enum ChessPiece board[8][8], int oldx, int oldy, int newx, int newy, enum ChessCastling *castling, char **enpassanttarget)
{
enum ChessPiece moving = board[oldx][oldy];
enum ChessPiece captured = board[newx][newy];
char *letters = "abcdefgh";
char *numbers = "87654321";
int epx, epy;
if (oldx == newx && oldy == newy)
{
return 0;
}
if (enpassanttarget && *enpassanttarget)
{
epx = strchr(letters, (*enpassanttarget)[0]) - letters;
epy = strchr(numbers, (*enpassanttarget)[1]) - numbers;
}
else
{
epx = -1;
epy = -1;
}
switch(moving)
{
case CP_WPAWN:
{
if (!IsPathClear(board, oldx, oldy, newx, newy))
{
return 0;
}
if (oldx == newx)
{
if (!captured && (newy == oldy - 1 || (newy == 4 && oldy == 6)))
{
return 1;
}
}
else if ((abs(oldx - newx) == 1) && (newy == oldy - 1))
{
if (captured != CP_EMPTY && !IsPieceWhite(captured))
{
return 1;
}
else if (captured == CP_EMPTY && newx == epx && newy == epy)
{
return 1;
}
}
return 0;
}
break;
case CP_BPAWN:
{
if (!IsPathClear(board, oldx, oldy, newx, newy))
{
return 0;
}
if (oldx == newx)
{
if (!captured && (newy == oldy + 1 || (newy == 3 && oldy == 1)))
{
return 1;
}
}
else if ((abs(oldx - newx) == 1) && (newy == oldy + 1))
{
if (captured != CP_EMPTY && IsPieceWhite(captured))
{
return 1;
}
else if (captured == CP_EMPTY && newx == epx && newy == epy)
{
return 1;
}
}
return 0;
}
case CP_WKNIGHT:
case CP_BKNIGHT:
{
if (!((abs(oldx - newx) == 2 && abs(oldy - newy) == 1) || (abs(oldx - newx) == 1 && abs(oldy - newy) == 2)))
{
return 0;
}
if (captured && IsPieceWhite(captured) == IsPieceWhite(moving))
{
return 0;
}
return 1;
}
break;
case CP_WBISHOP:
case CP_BBISHOP:
{
if (!IsPathClear(board, oldx, oldy, newx, newy))
{
return 0;
}
if (abs(oldx - newx) != abs(oldy - newy))
{
return 0;
}
return 1;
}
break;
case CP_WROOK:
case CP_BROOK:
{
if (!IsPathClear(board, oldx, oldy, newx, newy))
{
return 0;
}
if ((oldx - newx != 0) && (oldy - newy != 0))
{
return 0;
}
return 1;
}
case CP_WQUEEN:
case CP_BQUEEN:
{
if (!IsPathClear(board, oldx, oldy, newx, newy))
{
return 0;
}
if (((oldx - newx != 0) && (oldy - newy != 0)) && (abs(oldx - newx) != abs(oldy - newy)))
{
return 0;
}
return 1;
}
case CP_WKING:
case CP_BKING:
{
if (!IsPathClear(board, oldx, oldy, newx, newy))
{
return 0;
}
if (abs(oldx - newx) > 1 || abs(oldy - newy) > 1)
{
/* check for castling */
if (castling)
{
if (moving == CP_WKING && oldx == 4 && oldy == 7 && newy == 7)
{
if (newx == 6 && (*castling & CC_WK) != 0)
{
return 1;
}
if (newx == 2 && (*castling & CC_WQ) != 0)
{
return 1;
}
}
if (moving == CP_BKING && oldx == 4 && oldy == 0 && newy == 0)
{
if (newx == 6 && (*castling & CC_BK) != 0)
{
return 1;
}
if (newx == 2 && (*castling & CC_BQ) != 0)
{
return 1;
}
}
}
return 0;
}
return 1;
}
break;
default:
break;
}
return 0;
}
