Function mkstairs

src/mklev.c:2158–2197

Create stairs up or down at x,y. If force is TRUE, change the terrain to ROOM first */

/* Create stairs up or down at x,y.
   If force is TRUE, change the terrain to ROOM first */
void
mkstairs(
    coordxy x, coordxy y,
    char up,       /* [why 'char' when usage is boolean?] */
    struct mkroom *croom UNUSED,
    boolean force)
{
    int ltyp;
    d_level dest;

    if (!x || !isok(x, y)) {
        impossible("mkstairs:  bogus stair attempt at <%d,%d>", x, y);
        return;
    }
    if (force)
        levl[x][y].typ = ROOM;
    ltyp = levl[x][y].typ; /* somexyspace() allows ice */
    if (ltyp != ROOM && ltyp != CORR && ltyp != ICE) {
        int glyph = back_to_glyph(x, y),
            sidx = glyph_to_cmap(glyph);

        impossible("mkstairs:  placing stairs %s on %s at <%d,%d>",
                   up ? "up" : "down", defsyms[sidx].explanation, x, y);
    }

    /*
     * We can't make a regular stair off an end of the dungeon.  This
     * attempt can happen when a special level is placed at an end and
     * has an up or down stair specified in its description file.
     */
    if (dunlev(&u.uz) == (up ? 1 : dunlevs_in_dungeon(&u.uz)))
        return;

    dest.dnum = u.uz.dnum;
    dest.dlevel = u.uz.dlevel + (up ? -1 : 1);
    stairway_add(x, y, up ? TRUE : FALSE, FALSE, &dest);

    (void) set_levltyp(x, y, STAIRS);
    levl[x][y].ladder = up ? LA_UP : LA_DOWN;
}

/* is room a good one to generate up or down stairs in? */
staticfn boolean