function that returns nothing, RcppArmadillo

void permute(int ia_urn2[], int i_urn2_depth, int i_NP, int i_avoid, int ia_urn1[]) {
    int k = i_NP;
    int i_urn1 = 0;
    int i_urn2 = 0;
    for (int i = 0; i < i_NP; i++)
        ia_urn1[i] = i;                    /* initialize urn1 */

    i_urn1 = i_avoid;                      /* get rid of the index to be avoided and place it in position 0. */
    while (k > i_NP - i_urn2_depth) {      /* i_urn2_depth is the amount of indices wanted (must be <= NP) */
        ia_urn2[i_urn2] = ia_urn1[i_urn1]; /* move it into urn2 */
        ia_urn1[i_urn1] = ia_urn1[k-1];    /* move highest index to fill gap */
        k = k - 1;                         /* reduce number of accessible indices */
        i_urn2 = i_urn2 + 1;               /* next position in urn2 */
        i_urn1 = static_cast<int>(::unif_rand() * k);   /* choose a random index */
    }
}