cannam@95: Next: Wisdom Generic Export/Import from Fortran, cannam@95: Previous: Wisdom File Export/Import from Fortran, cannam@95: Up: Accessing the wisdom API from Fortran cannam@95:
Dealing with FFTW's C string export/import is a bit more painful. In
cannam@95: particular, the fftw_export_wisdom_to_string function requires
cannam@95: you to deal with a dynamically allocated C string. To get its length,
cannam@95: you must define an interface to the C strlen function, and to
cannam@95: deallocate it you must define an interface to C free:
cannam@95:
cannam@95:
use, intrinsic :: iso_c_binding cannam@95: interface cannam@95: integer(C_INT) function strlen(s) bind(C, name='strlen') cannam@95: import cannam@95: type(C_PTR), value :: s cannam@95: end function strlen cannam@95: subroutine free(p) bind(C, name='free') cannam@95: import cannam@95: type(C_PTR), value :: p cannam@95: end subroutine free cannam@95: end interface cannam@95:cannam@95:
Given these definitions, you can then export wisdom to a Fortran cannam@95: character array: cannam@95: cannam@95:
character(C_CHAR), pointer :: s(:) cannam@95: integer(C_SIZE_T) :: slen cannam@95: type(C_PTR) :: p cannam@95: p = fftw_export_wisdom_to_string() cannam@95: if (.not. c_associated(p)) stop 'error exporting wisdom' cannam@95: slen = strlen(p) cannam@95: call c_f_pointer(p, s, [slen+1]) cannam@95: ... cannam@95: call free(p) cannam@95:cannam@95:
cannam@95: Note that slen is the length of the C string, but the length of
cannam@95: the array is slen+1 because it includes the terminating null
cannam@95: character. (You can omit the ‘+1’ if you don't want Fortran to
cannam@95: know about the null character.) The standard c_associated function
cannam@95: checks whether p is a null pointer, which is returned by
cannam@95: fftw_export_wisdom_to_string if there was an error.
cannam@95:
cannam@95:
To import wisdom from a string, use
cannam@95: fftw_import_wisdom_from_string as usual; note that the argument
cannam@95: of this function must be a character(C_CHAR) that is terminated
cannam@95: by the C_NULL_CHAR character, like the s array above.
cannam@95:
cannam@95:
cannam@95:
cannam@95: