reduce

auto eve::reduce = functor<reduce_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overloads (non-splat)
   template <value T, typename Callable>
   element_type_t<T> reduce(T x, Callable f) requires(!O::contains(splat))     noexcept; // 1
 
   template <value T>
   element_type_t<T> reduce(T x) requires(!O::contains(splat))                 noexcept; // 1
 
   // Splat overloads
   template <simd_value T, typename Callable>
   T reduce(T x, Callable f) requires(O::contains(splat))                      noexcept; // 2
 
   template <simd_value T>
   T reduce(T x) requires(O::contains(splat))                                  noexcept; // 2
 
   // Lanes masking
   auto reduce[conditional_expr auto c](/* any of the above overloads */)      noexcept; // 3
   auto reduce[logical_value auto m](/* any of the above overloads */)         noexcept; // 3
}

Parameters

• x: argument.
• f: Callable to use for reduction.
• c: Conditional expression masking the operation.
• m: Logical value masking the operation.

Return value

1. The result of reducing all lanes with the given callable (or addition by default). Scalar values are returned as is.
2. The reduction result splatted across every lane of the input.
3. Same as any of the above but the masked lanes are ignored during the operation.

Example

#include <eve/module/core.hpp>
#include <eve/wide.hpp>
#include <iostream>
 
using wide_ft = eve::wide<float, eve::fixed<4>>;
using wide_it = eve::wide<std::int16_t, eve::fixed<4>>;
 
int main()
{
  wide_ft pf = {0.5f,1.5f,2.5f,3.f};
  wide_it qi = {2,3,4,5};
 
  auto const summ  = [](auto a, auto b) { return a+b; };
  auto const prod = [](auto a, auto b) { return a*b; };
 
  std::cout << "---- simd" << '\n'
            << "<- pf             = " << pf << '\n'
            << "-> reduce(pf,summ) = " << eve::reduce(pf, summ) << '\n'
            << "<- qi             = " << qi << '\n'
            << "-> reduce(qi,prod) = " << eve::reduce(qi, prod) << '\n';
 
  std::cout << "---- simd with splat" << '\n'
            << "<- pf                    = " << pf << '\n'
            << "-> reduce[splat](pf,summ) = " << eve::reduce[eve::splat](pf, summ) << '\n'
            << "<- qi                     = " << qi << '\n'
            << "-> reduce[splat](qi,prod) = " << eve::reduce[eve::splat](qi, prod) << '\n';
 
  return 0;
}