Function nextoid

src/mkobj.c:535–551

when splitting a stack that has o_id-based shop prices, pick an o_id value for the new stack that will maintain the same price */

/* when splitting a stack that has o_id-based shop prices, pick an
   o_id value for the new stack that will maintain the same price */
staticfn unsigned
nextoid(struct obj *oldobj, struct obj *newobj)
{
    int olddif, newdif, trylimit = 256; /* limit of 4 suffices at present */
    unsigned oid = svc.context.ident - 1; /* loop increment will reverse -1 */

    olddif = oid_price_adjustment(oldobj, oldobj->o_id);
    do {
        ++oid;
        if (!oid) /* avoid using 0 (in case value wrapped) */
            ++oid;
        newdif = oid_price_adjustment(newobj, oid);
    } while (newdif != olddif && --trylimit >= 0);
    svc.context.ident = oid; /* update 'last ident used' */
    (void) next_ident(); /* increment context.ident for next use */
    return oid; /* caller will use this ident */
}

/* try to find the stack obj was split from, then merge them back together;
   returns the combined object if unsplit is successful, null otherwise */