/* -*- P4_16 -*- */
#ifndef CHECKSUMS_P4
#define CHECKSUMS_P4

#include <core.p4>
#include <v1model.p4>

#include "headers.p4"

/*************************************************************************
*************   C H E C K S U M    V E R I F I C A T I O N   *************
*************************************************************************/

control MyVerifyChecksum(inout headers hdr, inout metadata meta) {
    apply {}
}

/*************************************************************************
**************   C H E C K S U M    C O M P U T A T I O N   **************
*************************************************************************/

control MyComputeChecksum(inout headers  hdr, inout metadata meta) {
    apply {
        /* 512 bit+ according to
        https://en.wikipedia.org/wiki/Transmission_Control_Protocol#TCP_checksum_for_IPv4
        */
			update_checksum_with_payload(
			hdr.ipv6.isValid(),
			{
                hdr.ipv6.src_addr, /* 128 */
				hdr.ipv6.dst_addr, /* 128 */
				meta.tcpLength,
				24w0,
				hdr.ipv6.next_header,
				// TCP header
				hdr.tcp.src_port,
				hdr.tcp.dst_port,
				hdr.tcp.seqNo,
				hdr.tcp.ackNo,
				hdr.tcp.data_offset,
				hdr.tcp.res,
				hdr.tcp.cwr,
				hdr.tcp.ece,
				hdr.tcp.urg,
				hdr.tcp.ack,
				hdr.tcp.psh,
				hdr.tcp.rst,
				hdr.tcp.syn,
				hdr.tcp.fin,
				hdr.tcp.window,
				hdr.tcp.urgentPtr
			},
			hdr.tcp.checksum,
			HashAlgorithm.csum16);

    }
}


#endif