// Copyright 2024 Matt Borland
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt

#ifndef BOOST_DECIMAL_DETAIL_CMATH_IMPL_FMA_HPP
#define BOOST_DECIMAL_DETAIL_CMATH_IMPL_FMA_HPP

#include <boost/decimal/decimal32_t.hpp>
#include <boost/decimal/decimal_fast32_t.hpp>
#include <boost/decimal/decimal64_t.hpp>
#include <boost/decimal/decimal128_t.hpp>
#include <boost/decimal/decimal_fast128_t.hpp>
#include <boost/decimal/detail/config.hpp>

namespace boost {
namespace decimal {

namespace detail {

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4127)
#endif

template <BOOST_DECIMAL_DECIMAL_FLOATING_TYPE Dec>
using components_type = std::conditional_t<std::is_same<Dec, decimal32_t>::value, decimal32_t_components,
                        std::conditional_t<std::is_same<Dec, decimal_fast32_t>::value, decimal_fast32_t_components,
                        std::conditional_t<std::is_same<Dec, decimal64_t>::value, decimal64_t_components,
                        std::conditional_t<std::is_same<Dec, decimal_fast64_t>::value, decimal_fast64_t_components,
                        std::conditional_t<std::is_same<Dec, decimal128_t>::value, decimal128_t_components, decimal_fast128_t_components
                        >>>>>;

template <bool checked, BOOST_DECIMAL_DECIMAL_FLOATING_TYPE T>
constexpr auto d32_fma_impl(T x, T y, T z) noexcept -> T
{
    using promoted_type = std::conditional_t<std::is_same<T, decimal32_t>::value, decimal64_t, decimal_fast64_t>;
    using promoted_components = components_type<promoted_type>;

    // Apply the add
    #ifndef BOOST_DECIMAL_FAST_MATH
    BOOST_DECIMAL_IF_CONSTEXPR (checked)
    {
        if (!isfinite(x) || !isfinite(y))
        {
            return detail::check_non_finite(x, y);
        }
    }
    #endif

    const auto x_components {x.to_components()};
    const auto y_components {y.to_components()};

    auto first_res {detail::mul_impl<promoted_components>(x_components, y_components)};

    // Apply the mul on the carried components
    // We still create the result as a decimal type to check for non-finite values and comparisons,
    // but we do not use it for the resultant calculation

    #ifndef BOOST_DECIMAL_FAST_MATH
    BOOST_DECIMAL_IF_CONSTEXPR (checked)
    {
        const T complete_lhs {first_res.sig, first_res.exp, first_res.sign};

        if (!isfinite(complete_lhs) || !isfinite(z))
        {
            return detail::check_non_finite(complete_lhs, z);
        }
    }
    #endif

    auto z_components {static_cast<promoted_components>(z.to_components())};
    detail::expand_significand<promoted_type>(z_components.sig, z_components.exp);
    detail::expand_significand<promoted_type>(first_res.sig, first_res.exp);

    return detail::add_impl<T>(first_res, z_components);
}

template <bool checked, BOOST_DECIMAL_DECIMAL_FLOATING_TYPE T>
constexpr auto d64_fma_impl(T x, T y, T z) noexcept -> T
{
    using promoted_type = std::conditional_t<std::is_same<T, decimal64_t>::value, decimal128_t, decimal_fast128_t>;
    using promoted_components = components_type<promoted_type>;

    // Apply the add
    #ifndef BOOST_DECIMAL_FAST_MATH
    BOOST_DECIMAL_IF_CONSTEXPR (checked)
    {
        if (!isfinite(x) || !isfinite(y))
        {
            return detail::check_non_finite(x, y);
        }
    }
    #endif

    const auto x_components {x.to_components()};
    const auto y_components {y.to_components()};

    auto first_res {detail::mul_impl<promoted_components>(x_components, y_components)};

    // Apply the mul on the carried components
    // We still create the result as a decimal type to check for non-finite values and comparisons,
    // but we do not use it for the resultant calculation
    const T complete_lhs {first_res.sig, first_res.exp, first_res.sign};

    #ifndef BOOST_DECIMAL_FAST_MATH
    BOOST_DECIMAL_IF_CONSTEXPR (checked)
    {
        if (!isfinite(complete_lhs) || !isfinite(z))
        {
            return detail::check_non_finite(complete_lhs, z);
        }
    }
    #endif

    auto z_components {static_cast<promoted_components>(z.to_components())};
    detail::expand_significand<promoted_type>(z_components.sig, z_components.exp);
    detail::expand_significand<promoted_type>(first_res.sig, first_res.exp);

    return detail::d128_add_impl_new<T>(first_res, z_components);
}

template <bool, BOOST_DECIMAL_DECIMAL_FLOATING_TYPE T>
constexpr auto d128_fma_impl(T x, T y, T z) noexcept -> T
{
    return x * y + z;
}

#ifdef _MSC_VER
#pragma warning(pop)
#endif

constexpr auto unchecked_fma(const decimal32_t x, const decimal32_t y, const decimal32_t z) noexcept -> decimal32_t
{
    return detail::d32_fma_impl<false>(x, y, z);
}

constexpr auto unchecked_fma(const decimal_fast32_t x, const decimal_fast32_t y, const decimal_fast32_t z) noexcept -> decimal_fast32_t
{
    return detail::d32_fma_impl<false>(x, y, z);
}

constexpr auto unchecked_fma(const decimal64_t x, const decimal64_t y, const decimal64_t z) noexcept -> decimal64_t
{
    return detail::d64_fma_impl<false>(x, y, z);
}

constexpr auto unchecked_fma(const decimal_fast64_t x, const decimal_fast64_t y, const decimal_fast64_t z) noexcept -> decimal_fast64_t
{
    return detail::d64_fma_impl<false>(x, y, z);
}

constexpr auto unchecked_fma(const decimal128_t x, const decimal128_t y, const decimal128_t z) noexcept -> decimal128_t
{
    return detail::d128_fma_impl<false>(x, y, z);
}

constexpr auto unchecked_fma(const decimal_fast128_t x, const decimal_fast128_t y, const decimal_fast128_t z) noexcept -> decimal_fast128_t
{
    return detail::d128_fma_impl<false>(x, y, z);
}

} // Namespace detail

BOOST_DECIMAL_EXPORT constexpr auto fma(const decimal32_t x, const decimal32_t y, const decimal32_t z) noexcept -> decimal32_t
{
    return detail::d32_fma_impl<true>(x, y, z);
}

BOOST_DECIMAL_EXPORT constexpr auto fma(const decimal64_t x, const decimal64_t y, const decimal64_t z) noexcept -> decimal64_t
{
    return detail::d64_fma_impl<true>(x, y, z);
}

BOOST_DECIMAL_EXPORT constexpr auto fma(const decimal128_t x, const decimal128_t y, const decimal128_t z) noexcept -> decimal128_t
{
    return detail::d128_fma_impl<true>(x, y, z);
}

BOOST_DECIMAL_EXPORT constexpr auto fma(const decimal_fast32_t x, const decimal_fast32_t y, const decimal_fast32_t z) noexcept -> decimal_fast32_t
{
    return detail::d32_fma_impl<true>(x, y, z);
}

BOOST_DECIMAL_EXPORT constexpr auto fma(const decimal_fast64_t x, const decimal_fast64_t y, const decimal_fast64_t z) noexcept -> decimal_fast64_t
{
    return detail::d64_fma_impl<true>(x, y, z);
}

BOOST_DECIMAL_EXPORT constexpr auto fma(const decimal_fast128_t x, const decimal_fast128_t y, const decimal_fast128_t z) noexcept -> decimal_fast128_t
{
    return detail::d128_fma_impl<true>(x, y, z);
}

} //namespace decimal
} //namespace boost

#endif //BOOST_DECIMAL_DETAIL_CMATH_IMPL_FMA_HPP