How to combine multiple top level C files?

[JulianKemmerer]

File level modules? extern things?

Each top level C file has N>=1 top level MAIN modules (with board io,etc).

Multiple instances of a collection of MAINs sounds smart to be able to package. Needed for complex multi clock domain stuff.

[JulianKemmerer]

pragmas for ports with sub-MAIN funcs. for two-func clock crossing 'instance of a file-module' - how to do clk crossing instances? macros?

[JulianKemmerer]

Static funcs? Unlike global functions in C, access to static functions is restricted to the file where they are declared

[JulianKemmerer]

What does extern mean for hardware - some kind of port maybe? Clock crossing?