Write a Fortran OML Library Using the Binary-compatible Interface

Follow these steps to write an OML library from a Fortran routine:

1. Compile the Fortran source code into an object.

   Using a Fortran compiler, compile myFortransub.f into myFortransub.o.

2. Add the standard C/C++ library OMLInterfacePublic.h to the Project folder.
3. Create a C/C++ file according to the Fortran function arguments,

   The C/C++ file must contain:

   • OML header to be used (OMLInterfacePublic.h).
   • Extern “C” block.
   • InitToolbox function.
   • C/C++ function calling the Fortran function.
4. Link the compiled Fortran file to the Project.
5. Compile the C/C++ code to create the DLL file (for example, omlFortran.dll).
6. To the Project folder, add the Fortran DLL that was called/used upon the Fortran compilation.
7. Import the DLL with the addlibrary function.

The Fortran routine in this example is myFortranSub.f90.

function myFortranSub(Method,Rs,Rz,RF)
	IF (Method == 1) THEN
		RF = 1/(Rs+Rz)
	ELSE IF (Method == 2) THEN
		RF = 1/(Rs**2+Rz**2)**.5
	ELSE
		RF = 1/(Rs+Rz)
	END IF
end function myFortranSub

The C++ code (leveraging the BCI OML APIs) is dllmain.cpp.

#include "OMLInterfacePublic.h"
extern "C"
{
    __declspec(dllexport) int InitToolbox(OMLInterface* eval);
    void __stdcall myfortransub_(int*,float*,float*,float*);
}

bool myFortranFunc(OMLInterface* eval, const OMLCurrencyList* inputs, OMLCurrencyList* outputs)
{
    if (inputs->Size() != 3)
        eval->ThrowError("Wrong number of arguments");

    const OMLCurrency* c1 = inputs->Get(0);
	const OMLCurrency* c2 = inputs->Get(1);
	const OMLCurrency* c3 = inputs->Get(2);

    if (!c1->IsScalar())
        eval->ThrowError("Invalid input type in argument 1");

	if (!c2->IsScalar())
        eval->ThrowError("Invalid input type in argument 2");

	if (!c3->IsScalar())
        eval->ThrowError("Invalid input type in argument 3");
	
	
    int input1 = (int)c1->GetScalar();
	float input2 = (float)c2->GetScalar();
	float input3 = (float)c3->GetScalar();
	float output1 = 0.0;

	myfortransub_(&input1, &input2, &input3, &output1);

	outputs->AddScalar(output1);
	
    return true;
}

int InitToolbox(OMLInterface* eval)
{
    eval->RegisterFunction("reservefactor", myFortranFunc);
    return 0;
}

The call to the Fortran routine is made by:

myfortransub_(&input1, &input2, &input3, &output1);