SigExp: Managed to Unmanaged Signature Converter
The converter consumes managed assemblies which it reflects on to find all P/Invoke declarations, types imported from COM, and delegates. It can be invoked using the P/Invoke Interop Assistant application or as a command line tool. In the Assistant, switch to the SigExp tab, open an assembly, and choose the method or type to convert. The corresponding C declarations appear in the Unmanaged signature box and tips in the Additional information box. The Options menu contains settings that influence the output (refer to the description below).