Quoted from stenlou
how to make it like a plugin available only when the DLL is installed/added.
At first using LoadLibrary() and GetProcAddress() winapi calls comes to mind. Problem is that Fortran 95 don't have procedure pointers. Maybe there is some trick to overcome that limitation? My Fortran skills are little bit limited but maybe someone more skilled could provide the answer?
Fortran 2003 makes this kind of things easy. Below is a Fortran 2003 sample to call procedure named hello that takes no parameters from test.dll.
module load_dll
use, intrinsic :: iso_c_binding, only: c_f_procpointer, c_funptr, c_intptr_t, &
c_null_char, c_char, c_associated
implicit none
interface
function LoadLibrary(lpFileName) bind(C, name='LoadLibraryA')
use, intrinsic :: iso_c_binding, only: c_intptr_t, c_char
character(kind=c_char) :: lpFileName(*)
!GCC$ ATTRIBUTES STDCALL :: LoadLibrary
integer(c_intptr_t) :: LoadLibrary
end function LoadLibrary
function GetProcAddress(hModule, lpProcName) bind(C, name='GetProcAddress')
use, intrinsic :: iso_c_binding, only: c_funptr, c_intptr_t, c_char
!GCC$ ATTRIBUTES STDCALL :: GetProcAddress
type(c_funptr) :: GetProcAddress
integer(c_intptr_t), value :: hModule
character(kind=c_char) :: lpProcName(*)
end function GetProcAddress
end interface
end module load_dll
module my_dll
use, intrinsic :: iso_c_binding, only: c_f_procpointer, c_funptr, c_intptr_t, &
c_null_char, c_char, c_associated
implicit none
abstract interface
subroutine hello() bind(C)
end subroutine hello
end interface
integer(c_intptr_t) :: module_handle
type(c_funptr) :: proc_address
procedure(hello), bind(C), pointer :: my_proc
end module my_dll
program main
use load_dll
use my_dll
implicit none
module_handle = LoadLibrary(c_char_'test.dll'//c_null_char)
if (module_handle == 0) stop 'Can''t load the DLL'
proc_address = GetProcAddress(module_handle, c_char_'hello'//c_null_char)
if (.not. c_associated(proc_address)) stop 'Can''t obtain the procedure address'
call c_f_procpointer(proc_address, my_proc)
call my_proc
end program main
