int64_t Murmur128Hash::inner_hash()

in cpp/src/common/container/murmur_hash3.cc [25:122]

• 80 lines of code
• 17 McCabe index (conditional complexity)

int64_t Murmur128Hash::inner_hash(const char *buf, int32_t len, int64_t seed) {
    const int block_count = len >> 4;  // as 128-bit blocks
    int64_t h1 = seed;
    int64_t h2 = seed;
    int64_t c1 = 0x87c37b91114253d5L;
    int64_t c2 = 0x4cf5ad432745937fL;

    for (int i = 0; i < block_count; i++) {
        int64_t k1 = get_block(buf, i * 2);
        int64_t k2 = get_block(buf, i * 2 + 1);
        k1 *= c1;
        k1 = rotl64(k1, 31);
        k1 *= c2;
        h1 ^= k1;
        h1 = rotl64(h1, 27);
        h1 += h2;
        h1 = h1 * 5 + 0x52dce729;
        k2 *= c2;
        k2 = rotl64(k2, 33);
        k2 *= c1;
        h2 ^= k2;
        h2 = rotl64(h2, 31);
        h2 += h1;
        h2 = h2 * 5 + 0x38495ab5;
    }

    int offset = block_count * 16;
    int64_t k1 = 0;
    int64_t k2 = 0;
    switch (len & 15) {
        case 15:
            k2 ^= ((int64_t)(buf[offset + 14])) << 48;
            // fallthrough
        case 14:
            k2 ^= ((int64_t)(buf[offset + 13])) << 40;
            // fallthrough
        case 13:
            k2 ^= ((int64_t)(buf[offset + 12])) << 32;
            // fallthrough
        case 12:
            k2 ^= ((int64_t)(buf[offset + 11])) << 24;
            // fallthrough
        case 11:
            k2 ^= ((int64_t)(buf[offset + 10])) << 16;
            // fallthrough
        case 10:
            k2 ^= ((int64_t)(buf[offset + 9])) << 8;
            // fallthrough
        case 9:
            k2 ^= buf[offset + 8];
            k2 *= c2;
            k2 = rotl64(k2, 33);
            k2 *= c1;
            h2 ^= k2;
            // fallthrough
        case 8:
            k1 ^= ((int64_t)buf[offset + 7]) << 56;
            // fallthrough
        case 7:
            k1 ^= ((int64_t)buf[offset + 6]) << 48;
            // fallthrough
        case 6:
            k1 ^= ((int64_t)buf[offset + 5]) << 40;
            // fallthrough
        case 5:
            k1 ^= ((int64_t)buf[offset + 4]) << 32;
            // fallthrough
        case 4:
            k1 ^= ((int64_t)buf[offset + 3]) << 24;
            // fallthrough
        case 3:
            k1 ^= ((int64_t)buf[offset + 2]) << 16;
            // fallthrough
        case 2:
            k1 ^= ((int64_t)buf[offset + 1]) << 8;
            // fallthrough
        case 1:
            k1 ^= buf[offset];
            k1 *= c1;
            k1 = rotl64(k1, 31);
            k1 *= c2;
            h1 ^= k1;
            break;
        default:  // 0
            // do nothing
            break;
    }

    h1 ^= len;
    h2 ^= len;
    h1 += h2;
    h2 += h1;
    h1 = fmix(h1);
    h2 = fmix(h2);
    h1 += h2;
    h2 += h1;
    return h1 + h2;
}