import hashlib


BUF_SZ = 4096


def hash_file_sha512(filename):
    res = hashlib.sha512()
    with open(filename, 'rb') as f:
        data = f.read(BUF_SZ)
        while data:
            res.update(data)
            data = f.read(BUF_SZ)
    return res.hexdigest()