def METHOD_NAME(dirpath: str, privkey_pem: bytes, cert_pem: bytes,
                    entropy: bytes, counter: int) -> None:
    """
    Write the setup directory.
    Args:
        dirpath: The directory path.
        key_pem: The private key PEM.
        cert_pem: The certificate PEM.
        entropy: The 48 bytes of entropy.
        counter: The counter value.
    """
    # Directory
    os.mkdir(dirpath)
    # Private key
    with open(f'{dirpath}/private-key.pem', 'bw') as f:
        f.write(privkey_pem)
    # Certificate
    with open(f'{dirpath}/certificate.pem', 'bw') as f:
        f.write(cert_pem)
    # Entropy
    with open(f'{dirpath}/entropy', 'wb') as f:
        f.write(entropy)
    # Counter
    with open(f'{dirpath}/counter', 'w') as f:
        f.write(f'{str(counter)}\n')