88 lines
3.0 KiB
Plaintext
88 lines
3.0 KiB
Plaintext
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module iso_c_utilities
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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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public :: c_to_f_string, c_f_dyn_string
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private
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character(c_char), dimension(1), save, target :: dummy_string = "?"
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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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! 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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contains
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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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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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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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end module
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