/** Score castling ability. */
private int castleBonus(Position pos)
{
if (pos.getCastleMask() == 0) return 0;
int k1 = kt1b[7*8+6] - kt1b[7*8+4];
int k2 = kt2b[7*8+6] - kt2b[7*8+4];
int t1 = qV + 2 * rV + 2 * bV;
int t2 = rV;
int t = pos.bMtrl - pos.bMtrlPawns;
int ks = interpolate(t, t2, k2, t1, k1);
int castleValue = ks + rt1b[7*8+5] - rt1b[7*8+7];
if (castleValue <= 0)
return 0;
ulong occupied = pos.whiteBB | pos.blackBB;
int tmp = (int) (occupied & 0x6E);
if (pos.a1Castle()) tmp |= 1;
if (pos.h1Castle()) tmp |= (1 << 7);
int wBonus = (castleValue * castleFactor[tmp]) >> 10;
tmp = (int) ((occupied >> 56) & 0x6E);
if (pos.a8Castle()) tmp |= 1;
if (pos.h8Castle()) tmp |= (1 << 7);
int bBonus = (castleValue * castleFactor[tmp]) >> 10;
return wBonus - bBonus;
}
/** Return a FEN string corresponding to a chess Position object. */
public static string toFEN(Position pos)
{
string ret = "";
// Piece placement
for (int r = 7; r >=0; r--) {
int numEmpty = 0;
for (int c = 0; c < 8; c++) {
int p = pos.getPiece(Position.getSquare(c, r));
if (p == Piece.EMPTY) {
numEmpty++;
} else {
if (numEmpty > 0) {
ret+=numEmpty.ToString();
numEmpty = 0;
}
switch (p) {
case Piece.WKING: ret+=('K'); break;
case Piece.WQUEEN: ret+=('Q'); break;
case Piece.WROOK: ret+=('R'); break;
case Piece.WBISHOP: ret+=('B'); break;
case Piece.WKNIGHT: ret+=('N'); break;
case Piece.WPAWN: ret+=('P'); break;
case Piece.BKING: ret+=('k'); break;
case Piece.BQUEEN: ret+=('q'); break;
case Piece.BROOK: ret+=('r'); break;
case Piece.BBISHOP: ret+=('b'); break;
case Piece.BKNIGHT: ret+=('n'); break;
case Piece.BPAWN: ret+=('p'); break;
default: throw new RuntimeException();
}
}
}
if (numEmpty > 0) {
ret += numEmpty.ToString();
}
if (r > 0) {
ret += ('/');
}
}
ret += (pos.whiteMove ? " w " : " b ");
// Castling rights
bool anyCastle = false;
if (pos.h1Castle()) {
ret += ('K');
anyCastle = true;
}
if (pos.a1Castle()) {
ret += ('Q');
anyCastle = true;
}
if (pos.h8Castle()) {
ret += ('k');
anyCastle = true;
}
if (pos.a8Castle()) {
ret += ('q');
anyCastle = true;
}
if (!anyCastle) {
ret += ('-');
}
// En passant target square
{
ret += (' ');
if (pos.getEpSquare() >= 0) {
int x = Position.getX(pos.getEpSquare());
int y = Position.getY(pos.getEpSquare());
ret += ((char)(x + 'a'));
ret += ((char)(y + '1'));
} else {
ret += ('-');
}
}
// Move counters
ret += " " + pos.halfMoveClock;
ret += " " + pos.fullMoveCounter;
return ret;
}
