nds_bswap
void nds_bswap(void *src, void *dst, size_t len);
nds_bswap(&tmp->frag_length, &hdr->frag_length,
nds_bswap(&tmp->auth_length, &hdr->auth_length,
nds_bswap(&tmp->call_id, &hdr->call_id, sizeof (DWORD));
nds_bswap(data, (unsigned char *)buf, n_bytes);