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src/panda/hash.cc  view on Meta::CPAN

namespace panda { namespace hash {

uint64_t hash_murmur64a (const char* str, size_t len) {
    const uint64_t seed = 7;
    const uint64_t m = 0xc6a4a7935bd1e995LLU;
    const int r = 47;

    const uint64_t * data = (const uint64_t *) str;
    const uint64_t * end = data + (len/8);

    uint64_t h = seed ^ (len * m);

    while (data != end) {
        uint64_t k = *data++;
        k *= m;
        k ^= k >> r;
        k *= m;

        h ^= k;
        h *= m;
    }

    const unsigned char * data2 = (const unsigned char*) data;
    switch (len & 7) {
    case 7: h ^= uint64_t(data2[6]) << 48; // fallthrough
    case 6: h ^= uint64_t(data2[5]) << 40; // fallthrough
    case 5: h ^= uint64_t(data2[4]) << 32; // fallthrough
    case 4: h ^= uint64_t(data2[3]) << 24; // fallthrough
    case 3: h ^= uint64_t(data2[2]) << 16; // fallthrough
    case 2: h ^= uint64_t(data2[1]) << 8; // fallthrough
    case 1: h ^= uint64_t(data2[0]);
            h *= m;
    };

    h ^= h >> r;
    h *= m;
    h ^= h >> r;

    return h;
}

uint32_t hash_jenkins_one_at_a_time (const char *key, size_t len) {
    uint32_t hash, i;
    for (hash = i = 0; i < len; ++i) {
        hash += key[i];
        hash += (hash << 10);
        hash ^= (hash >> 6);
    }
    hash += (hash << 3);
    hash ^= (hash >> 11);
    hash += (hash << 15);
    return hash;
}

char* crypt_xor (const char* source, size_t slen, const char* key, size_t klen, char* dest) {
    unsigned char* buf;
    if (dest) buf = (unsigned char*) dest;
    else {
        buf = (unsigned char*) malloc(slen+1); // space for '0'
        if (!buf) throw std::bad_alloc();
    }
    for (size_t i = 0; i < slen; ++i) buf[i] = ((unsigned char) source[i]) ^ ((unsigned char) key[i % klen]);
    buf[slen] = 0;
    return (char*) buf;
}

}}