void AddXrayPiece (int t, int sq, int side, BitBoard *b, BitBoard *c)
/***************************************************************************
*
* The purpose of this routine is to find a piece which attack through
* another piece (e.g. two rooks, Q+B, B+P, etc.) Side is the side attacking
* the square where the swapping is to be done.
*
***************************************************************************/
{
int dir, nsq, piece;
BitBoard a;
dir = directions[t][sq];
a = Ray[sq][dir] & board.blocker;
if (a == NULLBITBOARD)
return;
nsq = (t < sq ? leadz (a) : trailz (a));
piece = cboard[nsq];
if ((piece == queen) || (piece == rook && dir > 3) ||
(piece == bishop && dir < 4))
{
if (BitPosArray[nsq] & board.friends[side])
*b |= BitPosArray[nsq];
else
*c |= BitPosArray[nsq];
}
return;
}
int PinnedOnKing (int sq, int side)
/***************************************************************************
*
* Determine if the piece on sq is pinned against the King.
* Side is the color of the piece.
* Caveat: PinnedOnKing should only be called by GenCheckEscapes().
* The more generic FindPins() function should be used for evaluating
* pins against other pieces.
*
***************************************************************************/
{
int xside;
int KingSq, dir, sq1;
BitBoard b, blocker;
KingSq = board.king[side];
if ((dir = directions[KingSq][sq]) == -1)
return (false);
xside = 1 ^ side;
blocker = board.blocker;
/* Path from piece to king is blocked, so no pin */
if (FromToRay[KingSq][sq] & NotBitPosArray[sq] & blocker)
return (false);
b = (Ray[KingSq][dir] ^ FromToRay[KingSq][sq]) & blocker;
if (b == NULLBITBOARD)
return (false);
sq1 = (sq > KingSq ? leadz (b) : trailz (b));
/* If diagonal */
if (dir <= 3 &&
BitPosArray[sq1] & (board.b[xside][queen] | board.b[xside][bishop]))
return (true);
/* Rank / file */
if (dir >= 4 &&
BitPosArray[sq1] & (board.b[xside][queen] | board.b[xside][rook]))
return (true);
return (false);
}
// sn must be in network order
static inline int subnet4_to_prefixlen(uint32_t sn)
{
return 32 - trailz(ntohl(sn));
}
