Function SuperFastHash

libs/basekit/source/Hash_superfast.c:16–63

#endif

uint32_t SuperFastHash(const char *data, int len) {
    uint32_t hash = len, tmp;
    int rem;

    if (len <= 0 || data == NULL)
        return 0;

    rem = len & 3;
    len >>= 2;

    /* Main loop */
    for (; len > 0; len--) {
        hash += get16bits(data);
        tmp = (get16bits(data + 2) << 11) ^ hash;
        hash = (hash << 16) ^ tmp;
        data += 2 * sizeof(uint16_t);
        hash += hash >> 11;
    }

    /* Handle end cases */
    switch (rem) {
    case 3:
        hash += get16bits(data);
        hash ^= hash << 16;
        hash ^= data[sizeof(uint16_t)] << 18;
        hash += hash >> 11;
        break;
    case 2:
        hash += get16bits(data);
        hash ^= hash << 11;
        hash += hash >> 17;
        break;
    case 1:
        hash += *data;
        hash ^= hash << 10;
        hash += hash >> 1;
    }

    /* Force "avalanching" of final 127 bits */
    hash ^= hash << 3;
    hash += hash >> 5;
    hash ^= hash << 4;
    hash += hash >> 17;
    hash ^= hash << 25;
    hash += hash >> 6;

    return hash;
}