From: Tero Koskinen <tero.koskinen@iki.fi>
Subject: Re: Importing C function with variable argument list
Date: Tue, 10 Apr 2012 23:02:15 +0300
Date: 2012-04-10T23:02:15+03:00 [thread overview]
Message-ID: <20120410230215.502473d3a9f0287850900775@iki.fi> (raw)
In-Reply-To: 610ee323-4c7f-413d-8568-aed4955f5152@z38g2000vbu.googlegroups.com
Hi,
On Tue, 10 Apr 2012 02:21:59 -0700 (PDT)
Maxim Reznik <reznikmm@gmail.com> wrote:
> Hi, All
>
> It seems it's impossible to call C function variable argument lists
> from Ada.
> Even when one knows in advace all arguments at compile time.
>
> Functions with Variable Argument Lists have their own ABI. For
> instance, in x86_64:
>
> > When a function taking variable-arguments is called, %rax must be set to the
> > total number of floating point parameters passed to the function in vector registers.
...
> But it's impossible to specify this fact in pragma Import (C, ...
...
> What do you think?
To work-around this, I use a small wrapper for x86_64 (Linux)
environments in my curl bindings:
https://bitbucket.org/tkoskine/curl-ada/src/ebd5156f7334/Makefile#cl-6
https://bitbucket.org/tkoskine/curl-ada/src/ebd5156f7334/utils/easywrap.pl
https://bitbucket.org/tkoskine/curl-ada/src/ebd5156f7334/src/template/curl-easy.adb.tmpl#cl-144
Ada code is following:
procedure curl_easy_setopt
(C_Handle : CURL_Private_Access;
C_Option : CURL.Options.CURL_Option_Type;
C_Action : C_Action_Callback);
pragma Import (C, curl_easy_setopt, "wrap_setopt");
procedure curl_easy_setopt_data
(C_Handle : CURL_Private_Access;
C_Option : CURL.Options.CURL_Option_Type;
Data : Callback_Interface_Class_Access);
pragma Import (C, curl_easy_setopt_data, "wrap_setopt");
And C wrapper:
CURLcode wrap_setopt(CURL* handle, CURLoption option, void* param)
{
return curl_easy_setopt(handle, option, param);
}
For i386, I do s/wrap_setopt/curl_easy_setopt/ replacement before
compiling:
if ($Config{archname} =~ m/x86_86/) { $use_wrap = 1; }
while (<>) {
if ($use_wrap == 0) {
$_ =~ s/wrap_setopt/curl_easy_setopt/g;
}
print $_;
}
--
Tero Koskinen - http://iki.fi/tero.koskinen/
next prev parent reply other threads:[~2012-04-10 20:03 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-10 9:21 Importing C function with variable argument list Maxim Reznik
2012-04-10 11:22 ` Patrick
2012-04-10 13:09 ` Maxim Reznik
2012-04-10 13:50 ` Georg Bauhaus
2012-04-10 13:18 ` Markus Schöpflin
2012-04-10 16:47 ` Simon Wright
2012-04-12 10:08 ` Markus Schöpflin
2012-04-12 16:58 ` Adam Beneschan
2012-04-12 20:47 ` Randy Brukardt
2012-04-13 8:43 ` Markus Schöpflin
2012-04-13 23:01 ` Randy Brukardt
2012-04-27 8:24 ` Natasha Kerensikova
2012-04-27 9:18 ` Jacob Sparre Andersen
2012-04-27 16:48 ` Natasha Kerensikova
2012-05-03 20:15 ` sbelmont700
2012-05-13 4:18 ` David Thompson
2012-05-13 9:03 ` Simon Wright
2012-05-13 17:01 ` Jeffrey Carter
2012-05-13 18:20 ` Simon Wright
2012-05-13 19:11 ` Jeffrey Carter
2012-05-13 19:55 ` Ludovic Brenta
2012-05-14 0:52 ` Jeffrey Carter
2012-05-13 21:12 ` Simon Wright
2012-05-13 23:57 ` Georg Bauhaus
2012-05-14 0:54 ` Jeffrey Carter
2012-05-14 8:10 ` Nomen Nescio
2012-05-14 15:21 ` Natasha Kerensikova
2012-05-14 20:53 ` sbelmont700
2012-04-13 4:08 ` Tero Koskinen
2012-04-13 8:04 ` Markus Schöpflin
2012-04-10 20:02 ` Tero Koskinen [this message]
2012-04-13 3:28 ` Tero Koskinen
2012-04-10 20:25 ` sbelmont700
2012-04-11 23:24 ` Randy Brukardt
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