It appears you are using the emFile SW from Seeger.
The issue you are having is that the SdcFile_OpenFile() is a library call into the emFile library. Seeger did not include the source code for this library which includes this function. The best you can access is the declaration in the .h file.
Aside from the API calls to the library functions and do some sleuthing using assembly, Seeger has no plans at this time to include the source code.