force_cardinal

Detailed Description

Overrides the cardinal an algorithm iterates with.

Variables
template<int N>
constexpr auto	eve::algo::force_cardinal = (force_cardinal_key = eve::fixed<N>{})

Variable Documentation

force_cardinal

template<int N>

auto eve::algo::force_cardinal = (force_cardinal_key = eve::fixed<N>{})

inlineconstexpr

Header file #include <eve/module/algo.hpp>

namespace eve::algo
{
  template<int N> inline constexpr auto force_cardinal = eve_implementation_defined;
}

Template Parameters

N	Lanes handled at once.

Sets the cardinal of the loop, the number of lanes handled at once, to N. By default the cardinal comes from the types the range carries and from whether frequency scaling is allowed. Interacting with hand-written register code requires the trait, the register width being fixed there.

 
#include <eve/module/core.hpp>
#include <eve/module/algo.hpp>
 
#include <string>
#include <span>
 
#ifdef __SSSE3__
 
void remove_spaces(std::string& s)
{
  using u8x16 = eve::wide<std::uint8_t, eve::fixed<16>>;
 
  // eve only supports std::int8_t and std::uint8_t, not char.
  std::span s_bytes{reinterpret_cast<std::uint8_t*>(s.data()), s.size()};
 
  auto end = eve::algo::remove_if[eve::algo::force_cardinal<16>](
    s_bytes,[](u8x16 v) -> eve::logical<u8x16> {
    // A simd is_space we took from @aqrit
    __m128i lut = _mm_setr_epi8(' ',    0,    0,  0,
                                  0,    0,    0,  0,
                                  0, '\t', '\n',  0,
                                  0, '\r',    0,  0);
    return v == u8x16{_mm_shuffle_epi8(lut, v)};
  });
 
  auto offset = end - s_bytes.begin();
  s.erase(s.begin() + offset, s.end());
}
 
#endif  // __SSSE3__
 

See also

consider_types, allow_frequency_scaling