simd_resize.h

/* SPDX-License-Identifier: LGPL-3.0-or-later */
/* Copyright © 2022–2024 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH
 *                       Matthias Kretz <m.kretz@gsi.de>
 */
 
#ifndef VIR_SIMD_RESIZE_H
#define VIR_SIMD_RESIZE_H
 
#include "simd.h"
#include "detail.h"
 
namespace vir
{
  template <int N, typename T, typename A>
    constexpr vir::detail::deduced_simd<T, N>
    simd_resize(const stdx::simd<T, A>& x)
    {
      constexpr int xn = stdx::simd_size_v<T, A>;
      return vir::detail::deduced_simd<T, N>([&x](auto i) {
               if constexpr (i < xn)
                 return x[i];
               else
                 return T();
             });
    }
 
  template <int N, typename T, typename A>
    constexpr vir::detail::deduced_simd_mask<T, N>
    simd_resize(const stdx::simd_mask<T, A>& x)
    {
      constexpr int xn = stdx::simd_size_v<T, A>;
      return vir::detail::deduced_simd_mask<T, N>([&x](auto i) {
               if constexpr (i < xn)
                 return x[i];
               else
                 return false;
             });
    }
 
  template <typename V, typename A>
    constexpr std::enable_if_t<stdx::is_simd_v<V>, V>
    simd_size_cast(const stdx::simd<typename V::value_type, A>& x)
    {
      using T = typename V::value_type;
      constexpr int xn = stdx::simd_size_v<T, A>;
      return V([&x](auto i) {
               if constexpr (i < xn)
                 return x[i];
               else
                 return false;
             });
    }
 
  template <typename M, typename A>
    constexpr std::enable_if_t<stdx::is_simd_mask_v<M>, M>
    simd_size_cast(const stdx::simd_mask<typename M::simd_type::value_type, A>& x)
    {
#if VIR_GLIBCXX_STDX_SIMD
      return std::experimental::parallelism_v2::__proposed::resizing_simd_cast<M>(x);
#else
      using T = typename M::simd_type::value_type;
      constexpr int xn = stdx::simd_size_v<T, A>;
      return M([&x](auto i) {
               if constexpr (i < xn)
                 return x[i];
               else
                 return false;
             });
#endif
    }
}
 
#endif // VIR_SIMD_RESIZE_H