// ==================================================================
// Author: Jean-Michel Richer
// Date: August 2016
// Purpose: use of atomic operation fetch_add to perform reduction
// ==================================================================
#include <iostream>
#include <atomic>
#include <thread>
#include <cstdlib>
#include <cassert>
using namespace std;

int main() {
	const int SIZE = 1024;
	int *tab = new int [SIZE];

	for (int i= 0; i < SIZE; ++i) tab[i] = i+1;
	
	// reduction with atomic
	atomic<int> sum(0);
	
	for (int i = 0; i < SIZE; ++i) {
		sum.fetch_add(tab[i], std::memory_order_relaxed);
	}
	
	cout << "reduction=" << sum << endl;	
	assert(sum == (SIZE)*(SIZE+1)/2);
	
	return EXIT_SUCCESS;
}