WSJT-X/lib/iso_c_utilities.f90

88 lines
3.0 KiB
Fortran

module iso_c_utilities
use, intrinsic :: iso_c_binding, only: c_ptr, c_char, c_f_pointer, c_associated
implicit none
public :: c_to_f_string, c_f_dyn_string
private
character(c_char), dimension(1), save, target :: dummy_string = "?"
interface ! strlen is a standard C function from <string.h>
! int strlen(char *string)
function strlen (string) result (len) bind (c, name="strlen")
use, intrinsic :: iso_c_binding, only: c_ptr, c_size_t
implicit none
type(c_ptr), value :: string
integer(kind=c_size_t) :: len
end function strlen
! void free(void * p)
subroutine c_free (p) bind (c, name="free")
use, intrinsic :: iso_c_binding, only: c_ptr
implicit none
type(c_ptr), value :: p
end subroutine c_free
end interface
contains
!
! Cast C string pointer to Fortran string pointer
!
! Warning! - C data must outlive result scope
!
function c_to_f_string (c_str) result (f_str)
use, intrinsic :: iso_c_binding, only: c_ptr, c_f_pointer, c_char
implicit none
type(c_ptr), intent(in) :: c_str
character(kind=c_char, len=:), pointer :: f_str
character(kind=c_char), pointer :: arr(:)
interface ! strlen is a standard C function from <string.h>
! int strlen(char *string)
function strlen (string) result (len) bind (c, name="strlen")
use, intrinsic :: iso_c_binding, only: c_ptr, c_size_t
implicit none
type(c_ptr), value :: string
integer(kind=c_size_t) :: len
end function strlen
end interface
call c_f_pointer (c_str, arr, [strlen (c_str)])
call get_scalar_pointer (size (arr), arr, f_str)
end function c_to_f_string
subroutine get_scalar_pointer (scalar_len, scalar, fptr)
! Convert a null-terminated C string into a Fortran character pointer
use, intrinsic :: iso_c_binding, only: c_char
integer, intent(in) :: scalar_len
character(kind=c_char, len=scalar_len), intent(in), target :: scalar(1)
character(kind=c_char, len=:), pointer :: fptr
fptr => scalar(1)
end subroutine get_scalar_pointer
function c_f_dyn_string (cptr) result (fstr)
! Convert a null-terminated malloc'ed C string into a Fortran character array
type(c_ptr), intent(in) :: cptr ! The C address
character(kind=c_char), allocatable :: fstr(:)
character(kind=c_char), pointer :: fptr(:)
interface ! strlen is a standard C function from <string.h>
! void free(void * p)
subroutine c_free (p) bind (c, name="free")
use, intrinsic :: iso_c_binding, only: c_ptr
implicit none
type(c_ptr), value :: p
end subroutine c_free
end interface
if (c_associated (cptr)) then
call c_f_pointer (fptr=fptr, cptr=cptr, shape=[strlen(cptr)])
else
! To avoid segfaults, associate FPTR with a dummy target:
fptr => dummy_string
end if
fstr = fptr
call c_free (cptr)
end function c_f_dyn_string
end module