Function next_ident

src/mkobj.c:508–531

return the value of context.ident and then increment it to be ready for its next use; used to be simple += 1 so that every value from 1 to N got used but now has a random increase that skips half of potential values */

   its next use; used to be simple += 1 so that every value from 1 to N got
   used but now has a random increase that skips half of potential values */
unsigned
next_ident(void)
{
    unsigned res = svc.context.ident;

    /* +rnd(2): originally just +1; changed to rnd() to avoid potential
       exploit of player using #adjust to split an object stack in a manner
       that makes most recent ident%2 known; since #adjust takes no time,
       no intervening activity like random creation of a new monster will
       take place before next user command; with former +1, o_id%2 of the
       next object to be created was knowable and player could make a wish
       under controlled circumstances for an item that is affected by the
       low bits of its obj->o_id [particularly helm of opposite alignment] */
    svc.context.ident += rnd(2); /* ready for next new object or monster */

    /* if ident has wrapped to 0, force it to be non-zero; if/when it
       ever wraps past 0 (unlikely, but possible on a configuration which
       uses 16-bit 'int'), just live with that and hope no o_id conflicts
       between objects or m_id conflicts between monsters arise */
    if (!svc.context.ident)
        svc.context.ident = rnd(2) + 1;   /* id 1 is reserved */

    return res;
}

/* 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 */