// Copyright (2019-2022) Paul Scherrer Institute
// SPDX-License-Identifier: CERN-OHL-S-2.0 or GPL-3.0-or-later

#include "hls_jfjoch.h"

void udp(AXI_STREAM &eth_in,
         AXI_STREAM &udp_payload_out,
         hls::stream<ap_uint<UDP_METADATA_STREAM_WIDTH> > &udp_metadata_out,
         uint64_t& counter,
         volatile ap_uint<1> &in_clear_counters) {

#pragma HLS INTERFACE ap_ctrl_none port=return

#pragma HLS INTERFACE axis register both port=eth_in
#pragma HLS INTERFACE axis register both port=udp_payload_out
#pragma HLS INTERFACE axis register both port=udp_metadata_out
#pragma HLS INTERFACE ap_vld register port=counter
#pragma HLS INTERFACE ap_none register port=in_clear_counters

#pragma HLS pipeline II=1 style=flp

    enum   udp_state {INSPECT_HEADER, FORWARD, DISCARD};
    static udp_state state = INSPECT_HEADER;
    static packet_512_t packet_in, packet_out;
    static uint16_t eth_packets_expected;
    static uint16_t eth_packets_analyzed;
    static ap_uint<UDP_METADATA_STREAM_WIDTH> udp_metadata;

    static uint64_t internal_counter = 0;

    ap_uint<1> tmp = in_clear_counters;
    if (tmp)
        internal_counter = 0;

#pragma HLS RESET variable=state
#pragma HLS RESET variable=internal_counter

    ap_uint<16> udp_dest_port, udp_len;
    ap_uint<32> ipv4_source_ip;
    if (eth_in.read_nb(packet_in)) {

        packet_out.dest = 0;
        packet_out.user = 0;
        packet_out.id = 0;
        packet_out.last = packet_in.last;

        switch (state) {
            case INSPECT_HEADER:
                udp_len = get_header_field_16(packet_in.data, ipv4_payload_pos + 32);
                udp_dest_port = get_header_field_16(packet_in.data, ipv4_payload_pos + 16);
                udp_metadata_payload_size(udp_metadata) = udp_len - 8; // only payload
                udp_metadata_dest_port(udp_metadata) = udp_dest_port;

                eth_packets_expected =
                        (udp_payload_pos / 8 + udp_len) / 64 + ((udp_payload_pos / 8 + udp_len) % 64 ? 1 : 0);
                eth_packets_analyzed = 1;

                packet_out.data(511 - udp_payload_pos, 0) = packet_in.data(511, udp_payload_pos);

                if (packet_in.last)
                    udp_payload_out << packet_out;
                else
                    state = FORWARD;
                break;
            case FORWARD:
                packet_out.data(511, 512 - udp_payload_pos) = packet_in.data(udp_payload_pos - 1, 0);

                if (eth_packets_analyzed > eth_packets_expected) {
                    packet_out.last = 1;
                    state = DISCARD;
                }

                udp_payload_out << packet_out;
                packet_out.data(511 - udp_payload_pos, 0) = packet_in.data(511, udp_payload_pos);
                eth_packets_analyzed++;
                break;
            case DISCARD:
                break;
        }

        if (packet_in.last) {
            udp_metadata_eth_err(udp_metadata) = packet_in.user;
            udp_metadata_len_err(udp_metadata) = ((eth_packets_analyzed != eth_packets_expected) ? 1 : 0);

            udp_metadata_out << udp_metadata;
            state = INSPECT_HEADER;
            internal_counter++;
        }
    }

    counter = internal_counter;
}