scatterinterface.h

/*  This file is part of the Vc library. {{{
Copyright © 2014-2015 Matthias Kretz <kretz@kde.org>
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}}}*/

// scatters
// A scatter takes the following arguments:
// 1. A pointer to memory of any type that EntryType can convert to.
// 2. An indexes “vector”. The requirement is that the type implements the subscript operator,
//    stores «Size» valid index values, and each offset to the pointer above yields a valid
//    memory location for reading.
// 3. Optionally the third argument may be a mask. The mask disables several memory stores and
//    thus removes the requirements in (2.) for the disabled entries.

private:
    // enable_if<std::can_convert<MT, EntryType>::value && has_subscript_operator<IT>::value>
    template <typename MT, typename IT>
    inline void scatterImplementation(MT *mem, IT &&indexes) const;

    template <typename MT, typename IT>
    inline void scatterImplementation(MT *mem, IT &&indexes, MaskArgument mask) const;

public:
    #define Vc_ASSERT_SCATTER_PARAMETER_TYPES__                                                    \
        static_assert(std::is_convertible<EntryType, MT>::value,                                   \
                      "The memory pointer needs to point to a type that the EntryType of this "    \
                      "SIMD vector type can be converted to.");                                    \
        static_assert(                                                                             \
            Vc::Traits::has_subscript_operator<IT>::value,                                         \
            "The indexes argument must be a type that implements the subscript operator.");        \
        static_assert(!Traits::is_simd_vector<IT>::value || Traits::simd_vector_size<IT>::value >= Size, \
                      "If you use a SIMD vector for the indexes parameter, the index vector must " \
                      "have at least as many entries as this SIMD vector.");                       \
        static_assert(!std::is_array<T>::value ||                                                  \
                          (std::rank<T>::value == 1 &&                                             \
                           (std::extent<T>::value == 0 || std::extent<T>::value >= Size)),         \
                      "If you use a simple array for the indexes parameter, the array must have "  \
                      "at least as many entries as this SIMD vector.")


    template <typename MT,
              typename IT,
              typename = enable_if<Vc::Traits::has_subscript_operator<IT>::value>>
    Vc_INTRINSIC void scatter(MT *mem, IT &&indexes) const
    {
        Vc_ASSERT_SCATTER_PARAMETER_TYPES__;
        scatterImplementation(mem, std::forward<IT>(indexes));
    }

    template <typename MT,
              typename IT,
              typename = enable_if<Vc::Traits::has_subscript_operator<IT>::value>>
    Vc_INTRINSIC void scatter(MT *mem, IT &&indexes, MaskArgument mask) const
    {
        Vc_ASSERT_SCATTER_PARAMETER_TYPES__;
        scatterImplementation(mem, std::forward<IT>(indexes), mask);
    }

    template <typename MT, typename IT>
    Vc_INTRINSIC void scatter(const Common::ScatterArguments<MT, IT> &args) const
    {
        scatter(args.address, args.indexes);
    }

    template <typename MT, typename IT>
    Vc_INTRINSIC void scatter(const Common::ScatterArguments<MT, IT> &args, MaskArgument mask) const
    {
        scatter(args.address, args.indexes, mask);
    }
#undef Vc_ASSERT_SCATTER_PARAMETER_TYPES__