privilege.hh

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/*
    @@@@@@@@  @@           @@@@@@   @@@@@@@@ @@
   /@@/////  /@@          @@////@@ @@////// /@@
   /@@       /@@  @@@@@  @@    // /@@       /@@
   /@@@@@@@  /@@ @@///@@/@@       /@@@@@@@@@/@@
   /@@////   /@@/@@@@@@@/@@       ////////@@/@@
   /@@       /@@/@@//// //@@    @@       /@@/@@
   /@@       @@@//@@@@@@ //@@@@@@  @@@@@@@@ /@@
   //       ///  //////   //////  ////////  //

   Copyright (c) 2016, Triad National Security, LLC
   All rights reserved.
                                                                              */
#pragma once

#if !defined(__FLECSI_PRIVATE__)
#error Do not include this file directly!
#endif

#include "flecsi/util/bitutils.hh"

#include <cstddef>
#include <tuple>
#include <utility>

namespace flecsi {

enum partition_privilege_t : size_t {
  nu = 0b00,
  ro = 0b01,
  wo = 0b10,
  rw = 0b11
}; // enum partition_privilege_t

inline constexpr short privilege_bits = 2;

template<partition_privilege_t... PP>
inline constexpr size_t privilege_pack = [] {
  static_assert(((PP < 1 << privilege_bits) && ...));
  std::size_t ret = 1; // nonzero to allow recovering sizeof...(PP)
  ((ret <<= privilege_bits, ret |= PP), ...);
  return ret;
}();

constexpr size_t
privilege_count(std::size_t PACK) {
  return (util::bit_width(PACK) - 1) / privilege_bits;
} // privilege_count

constexpr partition_privilege_t
get_privilege(std::size_t i, std::size_t pack) {
  return partition_privilege_t(
    pack >> (privilege_count(pack) - 1 - i) * privilege_bits &
    ((1 << privilege_bits) - 1));
} // get_privilege

constexpr bool
privilege_write(std::size_t pack) noexcept {
  for(auto i = privilege_count(pack); i--;)
    if(get_privilege(i, pack) > ro)
      return true;
  return false;
}

} // namespace flecsi