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