passing subroutine names and interface blocks

[Brian_Murphy]

I'm an old dog, and new tricks don't come easy.  I'm trying to setup an interface block in a module for a routine which takes the name of a subroutine as one its arguments, and I'm stumped.  The argument "callback" will be the name of a subroutine which takes one input argument of the same type as the handle variable.  How does one declare the procedure argument?

INTERFACE
        function TF_SetLeaseCallback(handle, callback) bind(c, name = 'TF_SetLeaseCallback') result(retval) 
            import 
            integer(c_int32_t), value :: handle
            WHATGOESHERE :: callback 
            integer(c_long) :: retval
        end function 
        subroutine callback(status)
            integer(c_int32_t) :: status
        end subroutine
END INTERFACE

[Brian_Murphy]

I will study the code in quote #19 later today.

I have the C header file for the C library.  It is named Turbofloat.h and I have tried to attach it.  Here is the prototype for the C routine which takes a routine name as its second argument.

TURBOFLOAT_API HRESULT TF_CC TF_SetLeaseCallback(uint32_t handle, LeaseCallbackType callback);

Looking elsewhere in the header file for the other definitions.......

define TURBOFLOAT_API __declspec(dllimport)
define TF_CC __cdecl
typedef void(TF_CC * LeaseCallbackType)(uint32_t);

HRESULT seems to be coming from winnt.h as typedef _Return_type_success_(return >= 0) long HRESULT;

[andrew_4619]

typedef int32_t       HRESULT;

[FortranFan]

andrew_4619 wrote:

typedef int32_t       HRESULT;

If that C code (TURBO FLOAT?) is based on Microsoft Windows header(s), then better to follow Microsoft's own documentation:

https://docs.microsoft.com/en-us/windows/win32/winprog/windows-data-types

which defines HRESULT as

typedef LONG HRESULT;

with

typedef long LONG;