mirror of
https://gitlab.kitware.com/vtk/vtk-m
synced 2024-09-16 17:22:55 +00:00
125 lines
3.8 KiB
C++
125 lines
3.8 KiB
C++
//============================================================================
|
|
// Copyright (c) Kitware, Inc.
|
|
// All rights reserved.
|
|
// See LICENSE.txt for details.
|
|
//
|
|
// This software is distributed WITHOUT ANY WARRANTY; without even
|
|
// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
|
|
// PURPOSE. See the above copyright notice for more information.
|
|
//============================================================================
|
|
#ifndef vtk_m_random_Philox_h
|
|
#define vtk_m_random_Philox_h
|
|
|
|
#include <vtkm/Types.h>
|
|
|
|
namespace vtkm
|
|
{
|
|
namespace random
|
|
{
|
|
namespace detail
|
|
{
|
|
static inline VTKM_EXEC_CONT vtkm::Vec<vtkm::UInt32, 2> mulhilo(vtkm::UInt32 a, vtkm::UInt32 b)
|
|
{
|
|
vtkm::UInt64 r = static_cast<vtkm::UInt64>(a) * b;
|
|
auto lo = static_cast<vtkm::UInt32>(r);
|
|
vtkm::UInt32 hi = static_cast<vtkm::UInt32>(r >> 32);
|
|
return { lo, hi };
|
|
}
|
|
|
|
template <typename UIntType, std::size_t N, UIntType... consts>
|
|
struct philox_parameters;
|
|
|
|
template <typename T, T M0, T C0>
|
|
struct philox_parameters<T, 2, M0, C0>
|
|
{
|
|
static constexpr Vec<T, 1> multipliers = { M0 };
|
|
static constexpr Vec<T, 1> round_consts = { C0 };
|
|
};
|
|
|
|
template <typename T, T M0, T C0, T M1, T C1>
|
|
struct philox_parameters<T, 4, M0, C0, M1, C1>
|
|
{
|
|
static constexpr vtkm::Vec<T, 2> multipliers = { M0, M1 };
|
|
static constexpr vtkm::Vec<T, 2> round_consts = { C0, C1 };
|
|
};
|
|
|
|
template <typename UIntType, std::size_t N, std::size_t R, UIntType... consts>
|
|
class philox_functor;
|
|
|
|
template <typename UIntType, std::size_t R, UIntType... consts>
|
|
class philox_functor<UIntType, 2, R, consts...>
|
|
{
|
|
public:
|
|
using counters_type = vtkm::Vec<UIntType, 2>;
|
|
using keys_type = vtkm::Vec<UIntType, 1>;
|
|
|
|
VTKM_EXEC_CONT counters_type operator()(counters_type counters, keys_type keys) const
|
|
{
|
|
for (std::size_t i = 0; i < R; ++i)
|
|
{
|
|
counters = round(counters, keys);
|
|
keys = bump_keys(keys);
|
|
}
|
|
return counters;
|
|
}
|
|
|
|
private:
|
|
static VTKM_EXEC_CONT counters_type round(counters_type counters, keys_type round_keys)
|
|
{
|
|
auto constexpr multipliers = philox_parameters<UIntType, 2, consts...>::multipliers;
|
|
vtkm::Vec<UIntType, 2> r = mulhilo(multipliers[0], counters[0]);
|
|
return { r[1] ^ round_keys[0] ^ counters[1], r[0] };
|
|
}
|
|
|
|
static VTKM_EXEC_CONT keys_type bump_keys(keys_type keys)
|
|
{
|
|
auto constexpr round_consts = philox_parameters<UIntType, 2, consts...>::round_consts;
|
|
return { keys[0] + round_consts[0] };
|
|
}
|
|
};
|
|
|
|
template <typename UIntType, std::size_t R, UIntType... consts>
|
|
class philox_functor<UIntType, 4, R, consts...>
|
|
{
|
|
using counters_type = vtkm::Vec<UIntType, 4>;
|
|
using keys_type = vtkm::Vec<UIntType, 2>;
|
|
|
|
static VTKM_EXEC_CONT counters_type round(counters_type counters, keys_type round_keys)
|
|
{
|
|
auto constexpr multipliers = philox_parameters<UIntType, 4, consts...>::multipliers;
|
|
vtkm::Vec<UIntType, 2> r0 = mulhilo(multipliers[0], counters[0]);
|
|
vtkm::Vec<UIntType, 2> r1 = mulhilo(multipliers[1], counters[2]);
|
|
return {
|
|
r1[1] ^ round_keys[0] ^ counters[1], r1[0], r0[1] ^ round_keys[1] ^ counters[3], r0[0]
|
|
};
|
|
}
|
|
|
|
static VTKM_EXEC_CONT keys_type bump_key(keys_type keys)
|
|
{
|
|
auto constexpr round_consts = philox_parameters<UIntType, 4, consts...>::round_consts;
|
|
keys[0] += round_consts[0];
|
|
keys[1] += round_consts[1];
|
|
return keys;
|
|
}
|
|
|
|
public:
|
|
VTKM_EXEC_CONT counters_type operator()(counters_type counters, keys_type keys) const
|
|
{
|
|
for (std::size_t i = 0; i < R; ++i)
|
|
{
|
|
counters = round(counters, keys);
|
|
keys = bump_key(keys);
|
|
}
|
|
return counters;
|
|
}
|
|
};
|
|
|
|
} // namespace detail
|
|
|
|
using PhiloxFunctor2x32x7 = detail::philox_functor<vtkm::UInt32, 2, 7, 0xD256D193, 0x9E3779B9>;
|
|
using PhiloxFunctor2x32x10 = detail::philox_functor<vtkm::UInt32, 2, 10, 0xD256D193, 0x9E3779B9>;
|
|
|
|
} // namespace random
|
|
} // namespace vtkm
|
|
#endif //vtk_m_random_Philox_h
|