bf_segs
ds->ds_data = bf->bf_segs[0].ds_addr;
(caddr_t)bf->bf_segs[0].ds_addr, (u_int)bf->bf_segs[0].ds_len));
, roundup(bf->bf_segs[0].ds_len, 4) /* buffer length */
ds->ds_data = bf->bf_segs[0].ds_addr;
ds->ds_data = bf->bf_segs[i].ds_addr;
, bf->bf_segs[i].ds_len /* segment length */