how to integrate with the API(DLL) of external system by SAP PI

Hi Experts,

I did many integration activities with non-SAP systems by SOAP, JDBC or FILE using SAP PI, but now, i got a problem, the client have a 3rd party system which only expose APIs for integration which developed by C.

How can i do the integration by SAP PI? If SAP PI are not applicable, any other suggestions on this integration scenario?

Thanks a lot.