NAME¶

std::experimental::popcount - std::experimental::popcount

Synopsis¶

Defined in header <experimental/simd>
template< class T, class Abi > (parallelism TS v2)
int popcount( const simd_mask<T, Abi>& k ) noexcept;

Returns the number of true values in the mask k.

Parameters¶

k - the simd_mask to apply the reduction to

Return value¶

An int in the range [0, simd_size_v<T, Abi>).

Example¶

// Run this code

#include <cstddef>
#include <experimental/simd>
#include <iostream>
namespace stdx = std::experimental;

template<typename Abi>
int count_zeros(stdx::simd<int, Abi> v)
{
return stdx::popcount(v == 0); // v == 0 returns a simd_mask
}

void println(auto rem, auto const v)
{
std::cout << rem << ": ";
for (std::size_t i = 0; i != v.size(); ++i)
std::cout << v[i] << ' ';
}

int main()
{
stdx::simd<int> x{8};
println("x", x);
std::cout << " zeros: " << count_zeros(x) << '\n';

x[3] = x[1] = false;
println("x", x);
std::cout << " zeros: " << count_zeros(x) << '\n';
}

Possible output:¶

x: 8 8 8 8 zeros: 0
x: 8 0 8 0 zeros: 2