Function place_monster

src/steed.c:897–932

}

void
place_monster(struct monst *mon, coordxy x, coordxy y)
{
    struct monst *othermon;
    const char *monnm, *othnm;
    char buf[QBUFSZ];

    buf[0] = '\0';
    /* normal map bounds are <1..COLNO-1,0..ROWNO-1> but sometimes
       vault guards (either living or dead) are parked at <0,0> */
    if (!isok(x, y) && (x != 0 || y != 0 || !mon->isgd)) {
        describe_level(buf, 0);
        impossible("trying to place %s at <%d,%d> mstate:%lx on %s",
                   minimal_monnam(mon, TRUE), x, y, mon->mstate, buf);
        x = y = 0;
    }
    if ((mon == u.usteed && !gi.in_steed_dismounting)
        /* special case is for convoluted vault guard handling */
        || (DEADMONSTER(mon) && !(mon->isgd && x == 0 && y == 0))) {
        describe_level(buf, 0);
        impossible("placing %s onto map, mstate:%lx, on %s?",
                   (mon == u.usteed) ? "steed" : "defunct monster",
                   mon->mstate, buf);
        return;
    }
    if ((othermon = svl.level.monsters[x][y]) != 0) {
        describe_level(buf, 0);
        monnm = minimal_monnam(mon, FALSE);
        othnm = (mon != othermon) ? minimal_monnam(othermon, TRUE) : "itself";
        impossible("placing %s over %s at <%d,%d>, mstates:%lx %lx on %s?",
                   monnm, othnm, x, y, othermon->mstate, mon->mstate, buf);
    }
    mon->mx = x, mon->my = y;
    svl.level.monsters[x][y] = mon;
    mon->mstate = MON_FLOOR;
}

/*steed.c*/