static inline int find(const char *pat_data, int pat_size, const char *data, int data_size)
{
    int i;
    for (i = 0; i + pat_size <= data_size; ++i) {
#if 0
        int j = 0;
        while (j < pat_size && pat_data[j] == data[i + j]) ++j;
        if (j == pat_size) return i;
#else
        if (__builtin_bcmp(pat_data, data + i, pat_size) == 0) return i;
#endif
    }
    return -1;
}