RE: Passing lisp vector to foreign code

Sorry, I should mention that the ffi definition for get_bytes is

(fli:define-foreign-function
    (get-bytes "get_bytes" :source)
    ((db db)
     (nbytes (:reference-return :int)))
  :result-type (:pointer (:unsigned :char))
  :lambda-list (db &aux nbytes)
  :calling-convention :cdecl)

-----Original Message-----
From: Young, David [mailto:deyoung@bloodhoundinc.com]
Sent: Friday, July 29, 2005 10:38 AM
To: 'Martin Simmons'
Cc: lisp-hug@lispworks.com
Subject: RE: Passing lisp vector to foreign code


However, I got a suggestion to look at fli:replace-foreign-array. The
following code gives me this error:

Error: Attempting to get address of non string or signed-byte/unsigned-byte
vector: SIMPLE-VECTOR.
  1 (abort) Return to level 0.
  2 Return to top loop level 0.

Type :b for backtrace, :c <option number> to proceed,  or :? for other
options

Here's the revised code:

(defmethod fill-stream-buffer ((self binary-input-stream) db)
  (with-slots ((buf buffer)
               (len bufsiz)) self
    (multiple-value-bind (bytes nbytes)
        (get-bytes db)
      (let ((buf (make-array nbytes)))
        (fli:replace-foreign-array buf bytes)
        (setf len nbytes)))))

I've also tried (make-array nbytes :element-type 'unsigned-byte).

dey

-----Original Message-----
From: Martin Simmons [mailto:martin@lispworks.com]
Sent: Thursday, July 28, 2005 4:08 PM
To: deyoung@bloodhoundinc.com
Cc: lisp-hug@lispworks.com
Subject: Re: Passing lisp vector to foreign code


>>>>> On Thu, 28 Jul 2005 13:15:16 -0400, "Young, David"
<deyoung@bloodhoundinc.com> said:

  dey> Thanks. Here's how I got it working:

  dey> Outbound:

  dey> (let ((buf (output-buffer self))
  dey>       (bufsiz (buffer-size self)))
  dey>   (fli:with-dynamic-foreign-objects ()
  dey>     (let ((vector (fli:allocate-dynamic-foreign-object :type
`(:c-array
  dey> (:unsigned :char) ,bufsiz))))
  dey>       (dotimes (i bufsiz)
  dey>         (setf (fli:foreign-aref vector i) (aref buf i)))
  dey>       (put-bytes db vector bufsiz)

  dey> Inbound:

  dey> with-slots ((buf buffer)
  dey>              (len bufsiz)) self
  dey>   (multiple-value-bind (bytes nbytes)
  dey>       (get-bytes db)
  dey>     (let ((contents (loop for i from 0 below nbytes collect
(fli:dereference
  dey> bytes :index i))))
  dey>       (setf buf (make-array nbytes :initial-contents contents))
  dey>       (setf len (length buf)))))

  dey> Look reasonable?

What allocates the memory returned by get-bytes and should something free
it?

-- 
Martin Simmons                              Email: martin@lispworks.com
LispWorks Ltd, St John's Innovation Centre    TEL:   +44 1223 421860
Cowley Road, Cambridge CB4 0WS, England.      FAX:   +44 870 2206189



  dey> -----Original Message-----
  dey> From: Martin Simmons [mailto:martin@lispworks.com]
  dey> Sent: Thursday, July 28, 2005 1:10 PM
  dey> To: deyoung@bloodhoundinc.com
  dey> Cc: lisp-hug@lispworks.com
  dey> Subject: Re: Passing lisp vector to foreign code


>>>>> On Wed, 27 Jul 2005 11:26:44 -0400, "Young, David"
  dey> <deyoung@bloodhoundinc.com> said:

  dey> So, I have a binary stream class that collects bytes into a buffer
  dey> represented by a vector with a fill pointer. I want to take this
  dey> buffer and
  dey> send it to a C function, which stores it in a "database". Later, I
  dey> want to
  dey> retrieve this data via another binary stream class (we're
  dey> experimenting with
  dey> CL-STORE). Using the lw ffi, how do I set this up? It seems from the
  dey> docs
  dey> that I need to make a copy of the buffer in static space prior to
  dey> sending it
  dey> to C; is that correct? What should the ffi function declarations look
  dey> like?
  dey> Currently, I have:

  dey> (fli:define-foreign-function
  dey> (put-bytes "put_bytes" :source)
  dey> ((bytes (:c-array (:unsigned :char)))
  dey> (len :int))
  dey> :result-type :void
  dey> :calling-convention :cdecl)

  dey> (fli:define-foreign-function
  dey> (get-bytes "get_bytes" :source)
  dey> ((nbytes (:pointer (:int))))
  dey> :result-type (:c-array (:unsigned :char))
  dey> :calling-convention :cdecl)

  dey> But, passing a Lisp vector to PUT-BYTES yields a type error:

  dey> Expecting type (:foreign-array (:UNSIGNED :CHAR) (0)) (got #(76
  dey> ...))

  dey> so clearly I'm doing something wrong. Thanks for the help.

  dey> There are two kinds of static array: Lisp and foreign.  The :C-ARRAY
foreign
  dey> type needs a foreign array object (e.g. created with
  dey> FLI:ALLOCATE-FOREIGN-OBJECT).  See also the :LISP-ARRAY foreign type
if you
  dey> want to pass a static Lisp array pointer directly to C.

  dey> -- 
  dey> Martin Simmons                              Email:
martin@lispworks.com
  dey> LispWorks Ltd, St John's Innovation Centre    TEL:   +44 1223 421860
  dey> Cowley Road, Cambridge CB4 0WS, England.      FAX:   +44 870 2206189

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