philox_generic.hpp

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//============================================================================
// MCKL/include/mckl/random/internal/philox_generic.hpp
//----------------------------------------------------------------------------
// MCKL: Monte Carlo Kernel Library
//----------------------------------------------------------------------------
// Copyright (c) 2013-2018, Yan Zhou
// All rights reserved.
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// modification, are permitted provided that the following conditions are met:
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//   this list of conditions and the following disclaimer.
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//============================================================================

#ifndef MCKL_RANDOM_INTERNAL_PHILOX_GENERIC_HPP
#define MCKL_RANDOM_INTERNAL_PHILOX_GENERIC_HPP

#include <mckl/random/internal/common.hpp>
#include <mckl/random/internal/philox_common.hpp>
#include <mckl/random/internal/philox_generic_2x.hpp>
#include <mckl/random/internal/philox_generic_4x.hpp>
#include <mckl/random/internal/philox_unroll.hpp>
#include <mckl/random/increment.hpp>

namespace mckl {

namespace internal {

template <typename T, std::size_t K, std::size_t Rounds, typename Constants,
    int = std::numeric_limits<T>::digits>
class PhiloxGeneratorGenericImpl
{
  public:
    static void eval(
        const void *plain, void *cipher, const std::array<T, K / 2> &key)
    {
        alignas(MCKL_ALIGNMENT) union {
            std::array<T, K> s;
            std::array<char, sizeof(T) * K> r;
        } buf;

        std::memcpy(buf.s.data(), plain, sizeof(T) * K);
        union_le<char>(buf.s);
        MCKL_RANDOM_INTERNAL_PHILOX_UNROLL_ROUND(0, buf.s, key);
        union_le<T>(buf.r);
        std::memcpy(cipher, buf.s.data(), sizeof(T) * K);
    }

    template <typename ResultType>
    static void eval(
        Counter<T, K> &ctr, ResultType *r, const std::array<T, K / 2> &key)
    {
        alignas(MCKL_ALIGNMENT) union {
            std::array<T, K> s;
            Counter<T, K> c;
            std::array<ResultType, sizeof(T) * K / sizeof(ResultType)> r;
        } buf;

        MCKL_INLINE_CALL increment(ctr);
        buf.c = ctr;
#if MCKL_REQUIRE_ENDIANNESS_NEUTURAL
        union_le<typename Counter<T, K>::value_type>(buf.s);
#endif
        MCKL_RANDOM_INTERNAL_PHILOX_UNROLL_ROUND(0, buf.s, key);
#if MCKL_REQUIRE_ENDIANNESS_NEUTURAL
        union_le<T>(buf.r);
#endif
        std::memcpy(r, buf.r.data(), sizeof(T) * K);
    }

    template <typename ResultType>
    static void eval(Counter<T, K> &ctr, std::size_t n, ResultType *r,
        const std::array<T, K / 2> &key)
    {
        constexpr std::size_t R = sizeof(T) * K / sizeof(ResultType);

        for (std::size_t i = 0; i != n; ++i, r += R) {
            eval(ctr, r, key);
        }
    }

  private:
    template <std::size_t>
    static void round(
        std::array<T, K> &, const std::array<T, K / 2> &, std::false_type)
    {
    }

    template <std::size_t N>
    static void round(
        std::array<T, K> &s, const std::array<T, K / 2> &k, std::true_type)
    {
        MCKL_RANDOM_INTERNAL_PHILOX_UNROLL_ROUND(N, s, k);
    }

    template <std::size_t N>
    MCKL_INLINE static void rbox(
        std::array<T, K> &s, const std::array<T, K / 2> &k)
    {
        rbox<N>(s, k, std::integral_constant<bool, (N > 0 && N <= Rounds)>());
    }

    template <std::size_t>
    static void rbox(
        std::array<T, K> &, const std::array<T, K / 2> &, std::false_type)
    {
    }

    template <std::size_t N>
    static void rbox(
        std::array<T, K> &s, const std::array<T, K / 2> &k, std::true_type)
    {
        PhiloxRBox<T, K, N, Constants>::eval(s, k);
    }
}; // class PhiloxGeneratorGenericImpl

template <typename T, typename Constants, int D>
class PhiloxGeneratorGenericImpl<T, 2, 10, Constants, D>
    : public Philox2xGeneratorGenericImpl<T, Constants>
{
}; // class PhiloxGeneratorGenericImpl

template <typename T, typename Constants>
class PhiloxGeneratorGenericImpl<T, 2, 10, Constants, 64>
    : public Philox2x64GeneratorGenericImpl<T, Constants>
{
}; // class PhiloxGeneratorGenericImpl

template <typename T, typename Constants, int D>
class PhiloxGeneratorGenericImpl<T, 4, 10, Constants, D>
    : public Philox4xGeneratorGenericImpl<T, Constants>
{
}; // class PhiloxGeneratorGenericImpl

template <typename T, typename Constants>
class PhiloxGeneratorGenericImpl<T, 4, 10, Constants, 64>
    : public Philox4x64GeneratorGenericImpl<T, Constants>
{
}; // class PhiloxGeneratorGenericImpl

} // namespace internal

} // namespace mckl

#endif // MCKL_RANDOM_INTERNAL_PHILOX_GENERIC_HPP