Sum.h

/*
  ==============================================================================
    DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 
    Copyright 2022- by sonible GmbH.
 
    This file is part of VCTR - Versatile Container Templates Reconceptualized.
 
    VCTR is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License version 3
    only, as published by the Free Software Foundation.
 
    VCTR is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License version 3 for more details.
 
    You should have received a copy of the GNU Lesser General Public License
    version 3 along with VCTR.  If not, see <https://www.gnu.org/licenses/>.
  ==============================================================================
*/
 
namespace vctr::detail
{
template <class ValueType>
struct SumInit
{
    static constexpr ValueType value {};
};
 
template <class StringType>
requires std::convertible_to<const char*, StringType>
struct SumInit<StringType>
{
    static constexpr const char* value = "";
};
}
 
namespace vctr::expressions
{
 
template <size_t extent, class SrcType>
requires has::operatorPlusEquals<ValueType<SrcType>>
class Sum : public ExpressionTemplateBase
{
public:
    using value_type = ValueType<SrcType>;
 
    VCTR_COMMON_UNARY_EXPRESSION_MEMBERS (Sum, src)
 
    static constexpr auto reductionResultInitValue = detail::SumInit<value_type>::value;
 
    VCTR_FORCEDINLINE constexpr void reduceElementWise (value_type& result, size_t i) const
    {
        result += src[i];
    }
 
    //==============================================================================
    VCTR_FORCEDINLINE value_type reduceVectorOp() const
    requires is::suitableForAccelerateRealFloatVectorReductionOp<SrcType, value_type, detail::dontPreferIfIppAndAccelerateAreAvailable>
    {
        return Expression::Accelerate::sum (src.data(), size());
    };
 
    VCTR_FORCEDINLINE value_type reduceVectorOp() const
    requires is::suitableForIppRealOrComplexFloatVectorReductionOp<SrcType, value_type, detail::preferIfIppAndAccelerateAreAvailable>
    {
        return Expression::IPP::sum (src.data(), sizeToInt (size()));
    };
 
    //==============================================================================
    VCTR_FORWARD_PREPARE_SIMD_EVALUATION_UNARY_EXPRESSION_MEMBER_FUNCTIONS
 
    VCTR_FORCEDINLINE void reduceNeonRegisterWise (NeonRegister<value_type>& result, size_t i) const
    requires Config::archARM && has::getNeon<SrcType> && (is::realFloatNumber<value_type> || is::int32Number<value_type>)
    {
        result = Expression::Neon::add (result, src.getNeon (i));
    }
 
    VCTR_FORCEDINLINE VCTR_TARGET ("fma") void reduceAVXRegisterWise (AVXRegister<value_type>& result, size_t i) const
    requires Config::archX64 && has::getAVX<SrcType> && is::realFloatNumber<value_type>
    {
        result = Expression::AVX::add (result, src.getAVX (i));
    }
 
    VCTR_FORCEDINLINE VCTR_TARGET ("avx2") void reduceAVXRegisterWise (AVXRegister<value_type>& result, size_t i) const
    requires Config::archX64 && has::getAVX<SrcType> && is::int32Number<value_type>
    {
        result = Expression::AVX::add (result, src.getAVX (i));
    }
 
    VCTR_FORCEDINLINE VCTR_TARGET ("sse4.1") void reduceSSERegisterWise (SSERegister<value_type>& result, size_t i) const
    requires Config::archX64 && has::getSSE<SrcType> && (is::realFloatNumber<value_type> || is::int32Number<value_type>)
    {
        result = Expression::SSE::add (result, src.getSSE (i));
    }
 
    //==============================================================================
    template <size_t n>
    VCTR_FORCEDINLINE static constexpr value_type finalizeReduction (const std::array<value_type, n>& sums)
    {
        if constexpr (n == 1)
            return sums[0];
 
        return std::reduce (sums.begin(), sums.end());
    }
};
 
} // namespace vctr::expressions
 
namespace vctr
{
 
constexpr inline ExpressionChainBuilder<expressions::Sum> sum;
 
} // namespace vctr