putsum(uint8_t *data, uint32_t n, uint32_t sloc, uint32_t css, uint32_t cse)
{
    uint32_t sum;

    if (cse && cse < n)
        n = cse + 1;
    if (sloc < n-1) {
        sum = net_checksum_add(n-css, data+css);
        stw_be_p(data + sloc, net_checksum_finish_nozero(sum));
    }
}
Unknown