/* this assumes sub1 and sub2 are start points of two sub arrays of one contiguous array starting at sub1 with size elements */
int* merge ( int *sub1, int *sub2, int size )
{
    int *final= sub1, count= 0;
 
    while ( ++count < size )
    {
        if ( *sub1 > *sub2 )
        {
            /* if arr2 is less, move it to next slot in final */
            int *loc= sub2++;
            while ( loc-- > arr1 )
            {
                loc[0]^= loc[1];
                loc[1]^= loc[0];
                loc[0]^= loc[1];
            }
        }
        /* move the first pointer */
        arr1++;
    }
 
    return final;
}
 
int* merge_sort ( int *arr, int size )
{
    if ( size == 1 )
        return arr;
    else
        return merge( merge_sort( arr, size/2 ),
                      merge_sort( arr+size/2, size/2+size%2 ),
                      size );
}