int pure_memcmp(const void * const b1_, const void * const b2_, size_t len)
{
    const unsigned char *b1 = (const unsigned char *) b1_;
    const unsigned char *b2 = (const unsigned char *) b2_;
    size_t               i;
    unsigned char        d = (unsigned char) 0U;

    for (i = 0U; i < len; i++) {
        d |= b1[i] ^ b2[i];
    }
    return (int) ((1 & ((d - 1) >> 8)) - 1);
}
Unknown