Function split_mon

src/potion.c:2872–2915

clone a gremlin or mold (2nd arg non-null implies heat as the trigger); hit points are cut in half (odd HP stays with original) */

/* clone a gremlin or mold (2nd arg non-null implies heat as the trigger);
   hit points are cut in half (odd HP stays with original) */
struct monst *
split_mon(
    struct monst *mon,  /* monster being split */
    struct monst *mtmp) /* optional attacker whose heat triggered it */
{
    struct monst *mtmp2;
    char reason[BUFSZ];

    reason[0] = '\0';
    if (mtmp)
        Sprintf(reason, " from %s heat",
                (mtmp == &gy.youmonst) ? the_your[1]
                                    : (const char *) s_suffix(mon_nam(mtmp)));

    if (mon == &gy.youmonst) {
        if (u.mh > u.mhmax) /* sanity precaution */
            u.mh = u.mhmax;
        mtmp2 = (u.mh > 1) ? cloneu() : (struct monst *) 0;
        if (mtmp2) {
            /* mtmp2 has been created with mhpmax = u.mhmax, mhp = u.mh / 2,
               and u.mh -= mtmp2->mhp; these reductions for both max hp
               can't make either of them exceed corresponding current hp */
            mtmp2->mhpmax = u.mhmax / 2;
            u.mhmax -= mtmp2->mhpmax;
            disp.botl = TRUE;
            You("multiply%s!", reason);
        }
    } else {
        if (mon->mhp > mon->mhpmax) /* sanity precaution */
            mon->mhp = mon->mhpmax;
        mtmp2 = (mon->mhp > 1) ? clone_mon(mon, 0, 0) : (struct monst *) 0;
        if (mtmp2) {
            assert(mon->mhpmax >= mon->mhp); /* mon->mhpmax > 1 */
            /* mtmp2 has been created with mhpmax = mon->mhpmax,
               mhp = mon->mhp / 2, and mon->mh -= mtmp2->mhp;
               dividing max by 2 can't result in it exceeding current */
            mtmp2->mhpmax = mon->mhpmax / 2;
            mon->mhpmax -= mtmp2->mhpmax;
            if (canspotmon(mon))
                pline("%s multiplies%s!", Monnam(mon), reason);
        }
    }
    return mtmp2;
}

/* Character becomes very fast temporarily. */
void