atomic_fetch_and

 

atomic_fetch_and

emplate (integral) (1)	template <class T> T atomic_fetch_and (volatile atomic<T>* obj, T val) noexcept; template <class T> T atomic_fetch_and (atomic<T>* obj, T val) noexcept;
overloads (2)	T atomic_fetch_and (volatile A* obj, T val) noexcept; T atomic_fetch_and (A* obj, T val) noexcept;

将原子对象的封装值按位与 val，并返回原子对象的旧值（只适用于整型的 std::atomic 特化版本），整个过程是原子的

#include <iostream> 
#include <atomic> 
#include <stdio.h> 

int main()
{
  short int revents = 0x0888;
  short int revents2 = __atomic_fetch_and(&revents,0x0800,std::memory_order_seq_cst);
  printf("%4x and %4x \n", revents, revents2);
}

 

 

root@ubuntu:~/c++# ./atom4
 800 and  888