[Sbcl-devel] Obsolete passage in Manual re FFI

[Adam W. <li...@co...>]

Hi all,

[Christophe, thanks for fixing the format ~@F bug I reported]

In <http://www.sbcl.org/manual/Foreign-Type-Specifiers.html> it states:

   Lisp strings are stored with a trailing NUL termination, so no copying
   (either by the user or the implementation) is necessary when passing
   them to foreign code.

Characters in SBCL strings are now stored as 32-bit values:

(let ((sap (sb-sys:int-sap (sb-kernel:get-lisp-obj-address "ABC"))))
  (dotimes (i (* 3 4)) (format t "~A " (sb-sys:sap-ref-8 sap (1+ i)))))

=> 65 0 0 0 66 0 0 0 67 0 0 0

These obviously have to be copied to build a C string (pointer to a 0
terminated array of char).

Also:
<http://www.sbcl.org/manual/Step-By-Step-Example-of-the-Foreign-Function-Interface.html>

   Once the C code has been compiled, you can start up Lisp and load it
   in: sbcl Lisp should start up with its normal prompt.

I suspect this should read:

   Once the C code has been compiled, you can start up Lisp and load it
   in: (sb-alien:load-shared-object "test.so")

Regards,
Adam