switch (dirs) {
case DIR_NORTHEAST: return DIR_EAST;
case DIR_SOUTHEAST: return DIR_SOUTH;
case DIR_NORTHWEST: return DIR_NORTH;
case DIR_SOUTHWEST: return DIR_WEST;
default: return dirs;
}
}
/** Returns the available directions for a corner */
static gint
find_tip_directions(Point prev, Point this, Point next)
{
gint startdirs = find_slope_directions(prev, this);
gint enddirs = find_slope_directions(this, next);
gint firstdir = first_direction(startdirs);
gint lastdir = last_direction(enddirs);
gint dir, dirs = 0;
dir = firstdir;
while (dir != lastdir) {
dirs |= dir;
dir = dir * 2;
if (dir == 16) dir = 1;
}
dirs |= dir;
return dirs;
}
void
int
SqAttacked(short square, short side, short *blockable)
{
#ifdef SAVE_NEXTPOS
short d;
#else
unsigned char *ppos, *pdir;
#endif
short u, ptyp;
if (MatchSignature(threats_signature[side]))
{
*blockable = true; /* don't know */
return Anyattack(side, square);
}
/*
* First check neighbouring squares,
* then check Knights.
* then check Bishops,
* then (last) check Rooks,
*/
*blockable = false;
/* try a capture from direct neighboured squares */
ptyp = ptype[black][king];
#ifdef SAVE_NEXTPOS
u = first_direction(ptyp, &d, square);
#else
pdir = (*nextdir[ptyp])[square];
u = pdir[square];
#endif
do
{
if (color[u] == side) /* can piece reach square in one step ? */
#ifdef CHECK_DISTANCE
{
if (piece_distance(side, board[u], u, square) == 1)
return true;
}
#else
{
short v;
short ptypv = ptype[side][board[u]];
#ifdef SAVE_NEXTPOS
short dv;
v = first_direction(ptypv, &dv, u);
#else
unsigned char *qdir;
qdir = (*nextdir[ptypv])[u];
v = qdir[u];
#endif
do
{
if (v == square)
return true;
#ifdef SAVE_NEXTPOS
v = next_direction(ptypv, &dv, u);
#else
v = qdir[v];
#endif
}
while (v != u);
}
#endif
#ifdef SAVE_NEXTPOS
u = next_direction(ptyp, &d, square);
#else
u = pdir[u];
#endif
}
while (u != square);
/* try a knight capture (using xside's knight moves) */
ptyp = ptype[side ^ 1][knight];
#ifdef SAVE_NEXTPOS
u = first_direction(ptyp, &d, square);
#else
pdir = (*nextdir[ptyp])[square];
u = pdir[square];
#endif
do
{
if (color[u] == side && board[u] == knight)
return true;
#ifdef SAVE_NEXTPOS
u = next_direction(ptyp, &d, square);
#else
u = pdir[u];
#endif
}
while (u != square);
*blockable = true;
/* try a (promoted) bishop capture */
ptyp = ptype[black][bishop];
#ifdef SAVE_NEXTPOS
u = first_direction(ptyp, &d, square);
#else
ppos = (*nextpos[ptyp])[square];
pdir = (*nextdir[ptyp])[square];
u = ppos[square];
#endif
do
{
if (color[u] == neutral)
#ifdef SAVE_NEXTPOS
u = next_position(ptyp, &d, square, u);
#else
u = ppos[u];
#endif
else
{
if (color[u] == side && (unpromoted[board[u]] == bishop))
return true;
#ifdef SAVE_NEXTPOS
u = next_direction(ptyp, &d, square);
#else
u = pdir[u];
#endif
}
}
