UDPFragment.hh

#ifndef artdaq_ots_Overlays_UDPFragment_hh
#define artdaq_ots_Overlays_UDPFragment_hh
 
#include "artdaq-core/Data/Fragment.hh"
#include "cetlib_except/exception.h"
 
#include <ostream>
#include <vector>
 
namespace ots
{
class UDPFragment;
 
std::ostream& operator<<(std::ostream&, UDPFragment const&);
}  // namespace ots
 
class ots::UDPFragment
{
  public:
    struct Metadata
    {
        typedef uint64_t data_t;
 
        data_t port : 16;
        data_t address : 32;
        data_t unused : 16;
 
        static size_t const size_words = 1ull;  
    };
 
    static_assert(sizeof(Metadata) == Metadata::size_words * sizeof(Metadata::data_t),
                  "UDPFragment::Metadata size changed");
 
    struct Header
    {
        typedef uint32_t data_t;
 
        typedef uint32_t event_size_t;
        typedef uint32_t data_type_t;
 
        event_size_t event_size : 28;
        event_size_t type : 4;
 
        static size_t const size_words = 1ul;  
    };
 
    static_assert(sizeof(Header) == Header::size_words * sizeof(Header::data_t),
                  "UDPFragment::Header size changed");
 
    UDPFragment(artdaq::Fragment const& f) : artdaq_Fragment_(f) {}
 
    Header::event_size_t    hdr_event_size() const { return header_()->event_size; }
    Header::data_type_t     hdr_data_type() const { return header_()->type; }
    static constexpr size_t hdr_size_words() { return Header::size_words; }
 
    size_t udp_data_words() const
    {
        return (hdr_event_size() - hdr_size_words()) * bytes_per_word_();
    }
 
    uint8_t const* dataBegin() const
    {
        return reinterpret_cast<uint8_t const*>(header_() + 1);
    }
 
    uint8_t const* dataEnd() const { return dataBegin() + udp_data_words(); }
 
  protected:
    static constexpr size_t bytes_per_word_()
    {
        return sizeof(Header::data_t) / sizeof(uint8_t);
    }
 
    Header const* header_() const
    {
        return reinterpret_cast<UDPFragment::Header const*>(
            artdaq_Fragment_.dataBeginBytes());
    }
 
  private:
    artdaq::Fragment const& artdaq_Fragment_;
};
 
#endif /* artdaq_ots_Overlays_UDPFragment_hh */