Interlanguage calls

Your Fortran application can perform interlanguage calls to routines written in a language other than Fortran.

The guidelines assume that you are familiar with the syntax of all applicable languages.

Conventions for XL Fortran external names
To assist you in writing mixed-language programs, XL Fortran follows a consistent set of rules when translating the name of a global entity into an external name that the linker can resolve.
Mixed-language input and output
To improve performance, the XL Fortran runtime library has its own buffers and its own handling of these buffers. This means that mixed-language programs cannot freely mix I/O operations on the same file from the different languages.
Mixing Fortran and C++
When mixing Fortran and C++ in the same program, you need to invoke the C++ compiler to correctly link the final program.
Making calls to C functions work
When you pass an argument to a subprogram call, the usual Fortran convention is to pass the address of the argument. Many C functions expect arguments to be passed as values, however, not as addresses.
Passing data from one language to another
You need to account for corresponding data types in Fortran and C when passing data from one language to another.
Assembler-level subroutine linkage conventions
The subroutine linkage convention specifies the machine state at subroutine entry and exit, allowing routines that are compiled separately in the same or different languages to be linked.
Linkage convention for argument passing
The system linkage convention takes advantage of the large number of registers available.
Linkage convention for function calls
Function calls to a routine make use of its function descriptor and entry point symbols.
Prolog and epilog
You need to consider a number of steps when entering a procedure and when exiting a procedure.
Traceback
In 64–bit mode, the compiler supports the traceback mechanism, which symbolic debuggers need to unravel the call or return stack. Each object module has a traceback table in the text segment at the end of its code. This table contains information about the object module, including the type of object module, as well as stack frame and register information.