/*
 *  Copyright 2008-2021 NVIDIA Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#pragma once

#include <thrust/detail/config.h>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <thrust/random/detail/random_core_access.h>
#include <thrust/random/xor_combine_engine.h>

THRUST_NAMESPACE_BEGIN

namespace random
{

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE xor_combine_engine<Engine1, s1, Engine2, s2>::xor_combine_engine()
    : m_b1()
    , m_b2()
{} // end xor_combine_engine::xor_combine_engine()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE
xor_combine_engine<Engine1, s1, Engine2, s2>::xor_combine_engine(const base1_type& urng1, const base2_type& urng2)
    : m_b1(urng1)
    , m_b2(urng2)
{} // end xor_combine_engine::xor_combine_engine()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE xor_combine_engine<Engine1, s1, Engine2, s2>::xor_combine_engine(result_type s)
    : m_b1(s)
    , m_b2(s)
{} // end xor_combine_engine::xor_combine_engine()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE void xor_combine_engine<Engine1, s1, Engine2, s2>::seed()
{
  m_b1.seed();
  m_b2.seed();
} // end xor_combine_engine::seed()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE void xor_combine_engine<Engine1, s1, Engine2, s2>::seed(result_type s)
{
  m_b1.seed(s);
  m_b2.seed(s);
} // end xor_combine_engine::seed()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE const typename xor_combine_engine<Engine1, s1, Engine2, s2>::base1_type&
xor_combine_engine<Engine1, s1, Engine2, s2>::base1() const
{
  return m_b1;
} // end xor_combine_engine::base1()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE const typename xor_combine_engine<Engine1, s1, Engine2, s2>::base2_type&
xor_combine_engine<Engine1, s1, Engine2, s2>::base2() const
{
  return m_b2;
} // end xor_combine_engine::base2()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE typename xor_combine_engine<Engine1, s1, Engine2, s2>::result_type
xor_combine_engine<Engine1, s1, Engine2, s2>::operator()(void)
{
  return (result_type(m_b1() - base1_type::min) << shift1) ^ (result_type(m_b2() - base2_type::min) << shift2);
} // end xor_combine_engine::operator()()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE void xor_combine_engine<Engine1, s1, Engine2, s2>::discard(unsigned long long z)
{
  for (; z > 0; --z)
  {
    this->operator()();
  } // end for
} // end xor_combine_engine::discard()

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
template <typename CharT, typename Traits>
std::basic_ostream<CharT, Traits>&
xor_combine_engine<Engine1, s1, Engine2, s2>::stream_out(std::basic_ostream<CharT, Traits>& os) const
{
  typedef std::basic_ostream<CharT, Traits> ostream_type;
  typedef typename ostream_type::ios_base ios_base;

  // save old flags and fill character
  const typename ios_base::fmtflags flags = os.flags();
  const CharT fill                        = os.fill();

  const CharT space = os.widen(' ');
  os.flags(ios_base::dec | ios_base::fixed | ios_base::left);
  os.fill(space);

  // output each base engine in turn
  os << base1() << space << base2();

  // restore old flags and fill character
  os.flags(flags);
  os.fill(fill);
  return os;
}

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
template <typename CharT, typename Traits>
std::basic_istream<CharT, Traits>&
xor_combine_engine<Engine1, s1, Engine2, s2>::stream_in(std::basic_istream<CharT, Traits>& is)
{
  typedef std::basic_istream<CharT, Traits> istream_type;
  typedef typename istream_type::ios_base ios_base;

  // save old flags
  const typename ios_base::fmtflags flags = is.flags();

  is.flags(ios_base::skipws);

  // input each base engine in turn
  is >> m_b1 >> m_b2;

  // restore old flags
  is.flags(flags);
  return is;
}

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE bool
xor_combine_engine<Engine1, s1, Engine2, s2>::equal(const xor_combine_engine<Engine1, s1, Engine2, s2>& rhs) const
{
  return (m_b1 == rhs.m_b1) && (m_b2 == rhs.m_b2);
}

template <typename Engine1, size_t s1, typename Engine2, size_t s2, typename CharT, typename Traits>
std::basic_ostream<CharT, Traits>&
operator<<(std::basic_ostream<CharT, Traits>& os, const xor_combine_engine<Engine1, s1, Engine2, s2>& e)
{
  return thrust::random::detail::random_core_access::stream_out(os, e);
}

template <typename Engine1, size_t s1, typename Engine2, size_t s2, typename CharT, typename Traits>
std::basic_istream<CharT, Traits>&
operator>>(std::basic_istream<CharT, Traits>& is, xor_combine_engine<Engine1, s1, Engine2, s2>& e)
{
  return thrust::random::detail::random_core_access::stream_in(is, e);
}

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE bool operator==(const xor_combine_engine<Engine1, s1, Engine2, s2>& lhs,
                                  const xor_combine_engine<Engine1, s1, Engine2, s2>& rhs)
{
  return thrust::random::detail::random_core_access::equal(lhs, rhs);
}

template <typename Engine1, size_t s1, typename Engine2, size_t s2>
_CCCL_HOST_DEVICE bool operator!=(const xor_combine_engine<Engine1, s1, Engine2, s2>& lhs,
                                  const xor_combine_engine<Engine1, s1, Engine2, s2>& rhs)
{
  return !(lhs == rhs);
}

} // namespace random

THRUST_NAMESPACE_END
