Does the C extension API remain the same? ie can I take an existing extension and just recompile it, or does the code have to support a different API. I porte

Does the C extension API remain the same? ie can I take an existing extension and just recompile it, or does the code have to support a different API. I ported my main extension to PyPy but had to leave bits of functionality out because of missing parts of the API that CPython had that they didn't.