std::experimental::popcount
From cppreference.com
< cpp | experimental | simd
| Defined in header <experimental/simd>
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| template< class T, class Abi > int popcount( const simd_mask<T, Abi>& k ) noexcept; |
(parallelism TS v2) | |
Returns the number of true values in the mask k.
[edit] Parameters
| k | - | the simd_mask to apply the reduction to
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[edit] Return value
An int in the range [0, simd_size_v<T, Abi>).
[edit] 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
