c++ - SSE optimisation for a loop that finds zeros in an array and toggles a flag + updates another array

A piece of C++ code determines the occurances of zero and keeps a binary flag variable for each number that is checked. The value of the flag toggles between 0 and 1 each time a zero is encountered in a 1 dimensional array.

I am attempting to use SSE to speed it up, but I am unsure of how to go about this. Evaluating the individual fields of __m128i is inefficient, I've read.

The code in C++ is:

int flag = 0;
int var_num2[1000];
for(int i = 0; i<1000; i++)
{  
    if (var[i] == 0)
    {
        var_num2[i] = flag;

        flag = !flag;  //toggle value upon encountering a 0
     }
}

How should I go about this using SSE intrinsics?