From: Vladimir Zhbanov <vzhbanov@gmail.com>
To: guile-user@gnu.org
Subject: Re: Lepton EDA 1.9.14 announce and misc questions
Date: Wed, 21 Apr 2021 02:36:29 +0300 [thread overview]
Message-ID: <YH9lfdYcjtGnrpYk@lepton> (raw)
In-Reply-To: <510bfaf9-aa4f-50cd-deb3-7a15247a9bfa@gmail.com>
Hi Matt,
On Tue, Apr 20, 2021 at 06:46:27AM -0700, Matt Wette wrote:
>
>
> On 4/20/21 5:47 AM, Matt Wette wrote:
> >
> >
> > On 4/20/21 2:29 AM, Vladimir Zhbanov wrote:
> > > Hi Guile users and devs,
> > >
> > > I'm the current maintainer of Lepton EDA suite, an about five year
> > > old fork of geda-gaf with accent to moving more functionality to
> > > Scheme code. I'm not sure if it is acceptable to advertise it
> > > here, please let me know if not. I just know several Guix
> > > packagers are reading this mailing list and would like to announce
> > > a new version of Lepton, 1.9.14 has been released on April, 7:
> > >
> > > https://github.com/lepton-eda/lepton-eda/releases/tag/1.9.14-20210407
> > >
> > >
> >
> > Sweet. Thanks for posting this. I will take a look at your problem.
> > It'll require digging into the eda_..._dirs function.
> >
> >
> >
> The following should work as a complete program on a system w/ glib.
> You need to first convert the result to a bytevector and then access the
> elements (pointers) one at a time. Note that we don't know how big the
> array returned from the C function is. I pick an oversized value of 100.
>
> (use-modules (system foreign))
> (use-modules (rnrs bytevectors))
>
> (define glib (dynamic-link "libglib-2.0"))
>
> (define g-get-system-data-dirs
> (let ((f (pointer->procedure
> '* (dynamic-func "g_get_system_data_dirs" glib) (list)))
> (bv-pointer-ref (cond
> ((= (sizeof '*) 8) bytevector-u64-native-ref )
> ((= (sizeof '*) 4) bytevector-u32-native-ref )
> (else (error "hmmm"))))
> (BIG 100))
> (lambda ()
> (let* ((r (f))
> (p (pointer->bytevector r (* BIG (sizeof '*)))))
> (let loop ((ix 0))
> (let* ((ad (bv-pointer-ref p ix))
> (sp (make-pointer ad)))
> (if (equal? %null-pointer sp)
> '()
> (cons (pointer->string sp) (loop (+ ix (sizeof '*)))))))))))
>
> (simple-format #t "~S" (g-get-system-data-dirs))
Thank you for your replies!
Probably, I missed something here, so I'll try to elaborate a bit
on my initial question. The function eda_get_system_data_dirs()
mentioned in my first message has the same type, is defined the
same way using dynamic-func though in liblepton instead of glib,
and works on mostly the same array as glib's
g_get_system_data_dirs(). The function I've shown works well and
outputs the same results as yours. It simply uses a bit more
upper level interface, IIUC. So the first question is: I wonder,
if using bytevectors directly adds something here?
Another issue is a little more confusing for me. I read in
several places that even on the same system different compilators,
say gcc and g++, may use different alignment even for basic C
types like, say, double. What will they do on different platforms
then? May it be that (alignof '*) will be twice greater than
(sizeof '*)? In such a case using multiplied sizeof of pointer
for searching the location of a pointer in memory would be just
dangerous. I used sizeof in the first version of my code but
started to doubt if it is correct and how portable it is.
Thanks,
Vladimir
next prev parent reply other threads:[~2021-04-20 23:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 9:29 Lepton EDA 1.9.14 announce and misc questions Vladimir Zhbanov
2021-04-20 12:47 ` Matt Wette
2021-04-20 13:46 ` Matt Wette
2021-04-20 23:36 ` Vladimir Zhbanov [this message]
2021-04-21 0:34 ` Matt Wette
2021-04-21 7:53 ` Vladimir Zhbanov
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