compress_store

eve::compress_store = detail::compress_callable_no_density<compress_store_core> {}

inlineconstexpr

Defined in Header

#include <eve/module/core.hpp>

This function behaves like eve::compress_copy[dense] but as input it takes loaded register.

See also

eve::compres_copy for explained behavour.

Warning

you should use eve::compress_copy if possible, it has more opportunities for optimizations.

Callable Signatures

namespace eve
{
   template <relative_conditional_expr C1,
             relative_conditional_expr C2,
             simd_value T,
             logical_simd_value L,
             typename O>
   auto compress_store
       [safe/unsafe]
       [C1 ignore_in][C2 ignore_out]
       (T x, L m, O o)  -> unaligned_t<O> // (1)
}

Parameters

• safe/unsafe - mode of the operation - required
• ignore_in - optional, ignored elements considered not selected.
• ignore_out - optional, defaults to ignore_in. controls part of the output where the data will be written.
• x: simd_value to compress
• m: mask indicating selected elements
• o: pointer-like where to write the elements

Return value

• o after the last selected element written

Example

#include <eve/module/core.hpp>
#include <tts/tts.hpp>
 
using n = eve::fixed<4>;
using w_t = eve::wide<int, n>;
using l_t = eve::logical<eve::wide<std::uint8_t, n>>; // Note the type mismatch
 
int main()
{
  w_t in { 1,     2,      3,      4 };
  l_t m  { false, true, true, false };
 
  {
    // We have to have 4 elements in the output, even if only 2 are selected.
    std::array<int, 4> out {};
 
    int* o = eve::compress_store[eve::unsafe](in, m, out.data());
    TTS_EQUAL(2, o - out.data());  // 2 elements are selected and written
 
    // We don't know what elements are after
    out[2] = -1;
    out[3] = -1;
    TTS_EQUAL((std::array{2, 3, -1, -1}), out);
  }
 
  {
    // Here we know we won't write more than selected,
    // at the price of it being more expensive
    std::array<int, 2> out {};
    int* o = eve::compress_store[eve::safe](in, m, out.data());
 
    TTS_EQUAL(o - out.data(), 2);
    TTS_EQUAL((std::array{2, 3}), out);
  }
 
  {
    // Ignore output defaults to the input ignore.
    std::array<int, 3> out {-1, 0, 0};
    int* o = eve::compress_store[eve::unsafe][eve::keep_between(1, 3)](in, m, out.data());
 
    TTS_EQUAL(o - out.data(), 3);
    TTS_EQUAL((std::array{-1, 2, 3}), out);
  }
 
  {
    // But can be separate
    std::array<int, 3> out {0, -1, -1};
    int* o = eve::compress_store[eve::unsafe][eve::ignore_none][eve::keep_first(1)](in, m, out.data());
    TTS_EQUAL(o - out.data(), 1);
    TTS_EQUAL((std::array{2, -1, -1}), out);
  }
}