The F77 macros have been designed to cope with other systems as far as is possible. It should be possible to modify the include file f77.h to cope with most computers. The places where this may prove difficult, or even impossible, are likely to be due to arguments being passed in an unforeseen way.
The include file also declares the functions used for handling character strings. The declarations are written as function prototypes and assume that the C compiler will handle this feature of ANSI C. If a particular C compiler does not support this feature, then the header file could easily be modified to take this into account.
CNF and F77 Mixed Language Programming -- FORTRAN and C