icmp_checksum.c « pracownia1 « sieci « Semestr 4 - wmiuwr.git - My university solutions, lists and stuff. If you want to thank me for my notes, then buy me a craft beer (preferably IPA or baltic porter). Or just say *thank you* when we meet :)

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u_int16_t compute_icmp_checksum (const void *buff, int length)
{
	u_int32_t sum;
	const u_int16_t* ptr = buff;
	assert (length % 2 == 0);
	for (sum = 0; length > 0; length -= 2)
		sum += *ptr++;
	sum = (sum >> 16) + (sum & 0xffff);
	return (u_int16_t)(~(sum + (sum >> 16)));
}