A foreign resource that wants to be shared between several SICStus run-times must somehow know which SICStus run-time is calling it so that it can make callbacks using the SICStus API into the right SICStus run-time. In addition, the foreign resource may have global variables that should have different values depending on which SICStus run-time is calling the foreign resource.
A header file is generated by splfr when it builds a
foreign resource (before any C code is compiled). This header file
provides prototypes for any foreign-declared function, but it
also provides other things needed for multiple SICStus run-time
support. This header file must be included by any C file that contains
code that either calls any SICStus API function or that contains any of
the functions called by SICStus. See The Foreign Resource Linker.