Re: [Sbcl-help] Anolog of pointer-element-size in SBCL

[Dmitry I. <div...@gm...>]

Hugo Cienfuegos Suárez wrote on Thu, 26 Dec 2013 17:54:55 +0100 20:54:

HCS> As of the second cuestion maybe you could use sb-alien:addr
HCS> (let ((var (make-alien short 20)))
HCS>        (list (addr (deref var 0)) (addr (deref var 1))))
HCS> ;; => (#<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP #X7FFFE4000F70 :TYPE
HCS> (* (SIGNED 16))> ;;       #<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP
HCS> #X7FFFE4000F72 :TYPE (* (SIGNED 16))>)

Thanks a lot. I have managed to figure it out:

(defun %pointer-element-size (pointer)
  (- (sb-sys:sap-int (sb-alien:alien-sap
        (sb-alien:addr (sb-alien:deref pointer 1))))
     (sb-sys:sap-int (sb-alien:alien-sap
        (sb-alien:addr (sb-alien:deref pointer 0))))))
--
Sincerely,
Dmitry Ivanov
lisp.ystok.ru