代码

int binary_search(const unsigned *a, int n, unsigned x)
{
    int l = 0, r = n - 1;
    while (l < r) {
        int m = (l + r) >> 1;
        __builtin_prefetch(a + ((l + m) >> 1));
        __builtin_prefetch(a + ((m + r) >> 1));
        if (a[m] < x) l = m + 1; else r = m;
    }
    return l;
}

评测结果