/Src/Dependencies/Boost/boost/pool/detail/ct_gcd_lcm.hpp

  1// Copyright (C) 2000 Stephen Cleary
  2//
  3// Distributed under the Boost Software License, Version 1.0. (See
  4// accompanying file LICENSE_1_0.txt or copy at
  5// http://www.boost.org/LICENSE_1_0.txt)
  6//
  7// See http://www.boost.org for updates, documentation, and revision history.
  8
  9#ifndef BOOST_POOL_CT_GCD_LCM_HPP
 10#define BOOST_POOL_CT_GCD_LCM_HPP
 11
 12#include <boost/static_assert.hpp>
 13#include <boost/type_traits/ice.hpp>
 14
 15namespace boost {
 16
 17namespace details {
 18namespace pool {
 19
 20// Compile-time calculation of greatest common divisor and least common multiple
 21
 22//
 23// ct_gcd is a compile-time algorithm that calculates the greatest common
 24//  divisor of two unsigned integers, using Euclid's algorithm.
 25//
 26// assumes: A != 0 && B != 0
 27//
 28
 29#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 30
 31namespace details {
 32template <unsigned A, unsigned B, bool Bis0>
 33struct ct_gcd_helper;
 34template <unsigned A, unsigned B>
 35struct ct_gcd_helper<A, B, false>
 36{
 37  BOOST_STATIC_CONSTANT(unsigned, A_mod_B_ = A % B);
 38  BOOST_STATIC_CONSTANT(unsigned, value =
 39      (::boost::details::pool::details::ct_gcd_helper<
 40        B, static_cast<unsigned>(A_mod_B_),
 41        ::boost::type_traits::ice_eq<A_mod_B_, 0>::value
 42        >::value) );
 43};
 44template <unsigned A, unsigned B>
 45struct ct_gcd_helper<A, B, true>
 46{
 47  BOOST_STATIC_CONSTANT(unsigned, value = A);
 48};
 49} // namespace details
 50
 51template <unsigned A, unsigned B>
 52struct ct_gcd
 53{
 54  BOOST_STATIC_ASSERT(A != 0 && B != 0);
 55  BOOST_STATIC_CONSTANT(unsigned, value =
 56      (::boost::details::pool::details::ct_gcd_helper<A, B, false>::value) );
 57};
 58
 59#else
 60
 61// Thanks to Peter Dimov for providing this workaround!
 62namespace details {
 63template<unsigned A> struct ct_gcd2
 64{
 65  template<unsigned B>
 66  struct helper
 67  {
 68    BOOST_STATIC_CONSTANT(unsigned, value = ct_gcd2<B>::helper<A % B>::value);
 69  };
 70  template<>
 71  struct helper<0>
 72  {
 73    BOOST_STATIC_CONSTANT(unsigned, value = A);
 74  };
 75};
 76} // namespace details
 77
 78template<unsigned A, unsigned B> struct ct_gcd
 79{
 80  BOOST_STATIC_ASSERT(A != 0 && B != 0);
 81  enum { value = details::ct_gcd2<A>::helper<B>::value };
 82};
 83
 84#endif
 85
 86//
 87// ct_lcm is a compile-time algorithm that calculates the least common
 88//  multiple of two unsigned integers.
 89//
 90// assumes: A != 0 && B != 0
 91//
 92template <unsigned A, unsigned B>
 93struct ct_lcm
 94{
 95  BOOST_STATIC_CONSTANT(unsigned, value =
 96      (A / ::boost::details::pool::ct_gcd<A, B>::value * B) );
 97};
 98
 99} // namespace pool
100} // namespace details
101
102} // namespace boost
103
104#endif