How to utilize NetworkUtil::tcp_sum?

[Meraroo]

I don't know how to use tcp_sum () function..
Can you give me a hint?

[overflow218]

I'm just a student.
I'm not sure what you are curious about.
If you mean how to use tcp_sum() function,
You can refer src/Networking/E_networkUtil.cpp

uint16_t NetworkUtil::tcp_sum(uint32_t source, uint32_t dest,
const uint8_t *tcp_seg, size_t length) {
if (length < 20)
return 0;
struct pseudoheader pheader;
pheader.source = source;
pheader.destination = dest;
pheader.zero = 0;
pheader.protocol = IPPROTO_TCP;
pheader.length = htons(length);

uint32_t sum = one_sum((uint8_t *)&pheader, sizeof(pheader));
sum += one_sum(tcp_seg, length);
sum = (sum & 0xFFFF) + (sum >> 16);
return (uint16_t)sum;
}

[Meraroo]

Oh I found that initial value of checksum should be 0.. but I missed it.