Function vdev_draid_get_perm

freebsd/contrib/openzfs/module/zfs/vdev_draid.c:557–566

* Lookup the permutation array and iteration id for the provided offset. */

 * Lookup the permutation array and iteration id for the provided offset.
 */
static void
vdev_draid_get_perm(vdev_draid_config_t *vdc, uint64_t pindex,
    uint8_t **base, uint64_t *iter)
{
	uint64_t ncols = vdc->vdc_children;
	uint64_t poff = pindex % (vdc->vdc_nperms * ncols);

	*base = vdc->vdc_perms + (poff / ncols) * ncols;
	*iter = poff % ncols;
}

static inline uint64_t
vdev_draid_permute_id(vdev_draid_config_t *vdc,