#pragma once
#include <array>
#include <cstdint>

namespace eth {

using mac_addr = std::array<uint8_t, 6>;

static constexpr mac_addr MAC_BROADCAST = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
static constexpr uint16_t ETH_ARP = __builtin_bswap16(0x0806);
static constexpr uint16_t ETH_IPV4 = __builtin_bswap16(0x0800);

struct __attribute__((packed)) header {
    mac_addr dst;
    mac_addr src;
    uint16_t ethertype;
};
static_assert(sizeof(header) == 14);

template <typename Buf>
void prepend(Buf& buf, const mac_addr& dst, const mac_addr& src, uint16_t ethertype) {
    auto* h = buf.template prepend<header>();
    h->dst = dst;
    h->src = src;
    h->ethertype = ethertype;
}

} // namespace eth