NAME¶

std::experimental::find_first_set,std::experimental::find_last_set - std::experimental::find_first_set,std::experimental::find_last_set

Synopsis¶

Defined in header <experimental/simd>
template< class T, class Abi > (1) (parallelism TS v2)
int find_first_set( const simd_mask<T, Abi>& k );
template< class T, class Abi > (2) (parallelism TS v2)
int find_last_set( const simd_mask<T, Abi>& k );

1) Returns the lowest index i where k[i] is true.
2) Returns the greatest index i where k[i] is true.

The behavior is undefined if any_of(k) is false.

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 find(stdx::simd_mask<Abi> const& v)
{
if (stdx::any_of(v))
return find_first_set(v);
return -1;
}

int main()
{
stdx::simd_mask<short> a{0};
a[2] = a[a.size() - 2] = 1;

for (std::size_t i = 0; i < a.size(); ++i)
std::cout << a[i] << ' ';
std::cout << '\n';

std::cout << "find_first_set: " << stdx::find_first_set(a) << '\n';
std::cout << "find_last_set: " << stdx::find_last_set(a) << '\n';
std::cout << "find: " << find(a) << '\n';
a[2] = 0;
std::cout << "find: " << find(a) << '\n';
a[a.size() - 2] = 0;
std::cout << "find: " << find(a) << '\n';
}

Possible output:¶

0 0 1 0 0 0 1 0
find_first_set: 2
find_last_set: 6
find: 2
find: 6
find: -1