[Ecls-list] arrays as parameters to c-inlined code

[marc daya]

Greetings,

I'm trying to pass an array reference to c-inlined code, without much
success.  Well, I can get it into the c-inlined code, I just can't
seem to do anything with it when it comes out.  I have the feeling
that there's something fundamental that I don't understand, so I'd be
grateful for any pointers...  I'm really not sure where to go from
here.

I've tried using the approaches below, but both fail when any attempt
is made to access the array once the C-code completes.  In both cases
the C-code seems to execute correctly, but then breaks as follows:

  > (load "test.fas")
   ;;; Loading "c:/_/pvt/tmp/test.fas"
   "c:/_/pvt/tmp/test.fas"
   > (load-native-constants-0)
   [0] : 2
   [1] : 4
   [2] : 8
   Broken at EVAL.No restarts available.
   Broken at LOAD-NATIVE-CONSTANTS-0.
   >> (quit)
   3435462 is not of type SI:FOREIGN-DATA.

In the error above, the final error message shows after the (quit)
because of the way rxvt captures the output.  I've produced this
output on Windows under MinGW, but I see the same problems on Linux.

The code that I've tried is:

[1] using with-foreign-object

   (defun load-native-constants-0 ()

     (ffi:with-foreign-object
       (consts '(:array :unsigned-byte 3))

       (ffi:clines "#include <sys/types.h>")
       (ffi:c-inline
         (consts) (:unsigned-byte*)
         :void    ; no return value
         "{
            uint8_t* consts = #0;
            consts[0] = 2;
            printf(\"[0] : %d\\n\", consts[0]);
            consts[1] = 4;
            printf(\"[1] : %d\\n\", consts[1]);
            consts[2] = 8;
            printf(\"[2] : %d\\n\", consts[2]);
         }")))

[2] using def-array-pointer and allocate-foreign-object

   (defun load-native-constants-1 ()

     (ffi:def-array-pointer Uint8-array :unsigned-byte)

     (let ((var-count 3))
       (let ((consts (ffi::allocate-foreign-object 'Uint8-array var-count)))

         (format t "consts is : ~a~%" consts)

         (ffi:clines "#include <sys/types.h>")
         (ffi:c-inline
           (consts) ('Uint8-array)
           :void     ; no return value
           "{
              uint8_t* consts = #0;
              consts[0] = 2;
              printf(\"[0] : %d\\n\", consts[0]);
              consts[1] = 4;
              printf(\"[1] : %d\\n\", consts[1]);
              consts[2] = 8;
              printf(\"[2] : %d\\n\", consts[2]);
           }")

           (ffi:deref-array consts 'Uint8-array 0))))

Thanks,
.marc