MurmurHash64B

def bytes_to_int32(bytes):
    assert len(bytes) == 4
    return sum((b << (k * 8) for k, b in enumerate(bytes)))

def MurmurHash64B(data, seed):
    m = 0x5bd1e995
    r = 24    
    MASK = 0xFFFFFFFF
    data_as_bytes = bytearray(data)
    
    length = len(data_as_bytes) & MASK
    h1 = (seed & MASK) ^ length;
    h2 = 0;
    
    index = 0
    while(length >= 8):
        k1 = bytes_to_int32(data_as_bytes[index:index+4])
        k1 = (k1 * m) & MASK; k1 = k1 ^ ((k1 >> r) & MASK); k1 = (k1 * m) & MASK;
        h1 = (h1 * m) & MASK; h1 = h1 ^ k1;
        length -= 4;
        index  += 4;

        k2 = bytes_to_int32(data_as_bytes[index:index+4])
        k2 = (k2 * m) & MASK; k2 = k2 ^ ((k2 >> r) & MASK); k2 = (k2 * m) & MASK;
        h2 = (h2 * m) & MASK; h2 = h2 ^ k2;
        length -= 4;
        index  += 4;
    
    if(length >= 4):
    k3 = bytes_to_int32(data_as_bytes[index:index+4])
    k3 = (k3 * m) & MASK; k3 = k3 ^ ((k3 >> r) & MASK); k3 = (k3 * m) & MASK;
    h1 = (h1 * m) & MASK; h1 = h1 ^ k3;
    length -= 4;
    index  += 4;
    
    if(length == 3):
    h2 = h2 ^ ((data_as_bytes[index+2] << 16) & MASK )
    h2 = h2 ^ ((data_as_bytes[index+1] << 8 ) & MASK )
    h2 = h2 ^ (data_as_bytes[index+0])
    h2 = (h2 * m) & MASK;
    if(length == 2):
    h2 = h2 ^ ((data_as_bytes[index+1] << 8 ) & MASK )
    h2 = h2 ^ (data_as_bytes[index+0])
    h2 = (h2 * m) & MASK;
    if(length == 1):
    h2 = h2 ^ (data_as_bytes[index+0])
    h2 = (h2 * m) & MASK;
    
    h1 = h1 ^ ((h2 >> 18) & MASK ); h1 = (h1 * m) & MASK;
    h2 = h2 ^ ((h1 >> 22) & MASK ); h2 = (h2 * m) & MASK;
    h1 = h1 ^ ((h2 >> 17) & MASK ); h1 = (h1 * m) & MASK;
    h2 = h2 ^ ((h1 >> 19) & MASK ); h2 = (h2 * m) & MASK;

    h = h1;
    h = ((h << 32) & 0xFFFFFFFFFFFFFFFF) | h2;    
    return h