From:	"clusty" <clusty AT poland DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: inline assembly and c struct
Date:	Thu, 1 Feb 2001 17:51:38 +0100
Organization:	news.onet.pl
Lines:	56
Sender:	[clusty.friko4.onet.pl]@ppp-12.cuprum.com.pl
Message-ID:	<95f5mk$cug$1@news.onet.pl>
References:	<957ghs$kl$1 AT news DOT onet DOT pl> <959619$f3k$1 AT murdoch DOT acc DOT Virginia DOT EDU>
NNTP-Posting-Host:	ppp-12.cuprum.com.pl
X-Trace:	news.onet.pl 981146132 13264 195.117.119.140 (2 Feb 2001 20:35:32 GMT)
X-Complaints-To:	abuse AT onet DOT pl
NNTP-Posting-Date:	2 Feb 2001 20:35:32 GMT
X-Newsreader:	Microsoft Outlook Express 5.00.2919.6600
X-MSMail-Priority:	Normal
X-Priority:	3
X-MimeOLE:	Produced By Microsoft MimeOLE V5.00.2919.6600
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

In article news:959619$f3k$1 AT murdoch DOT acc DOT Virginia DOT EDU , "Clark L. Coleman"
clc5q AT cobra DOT cs DOT Virginia DOT EDU>... wrote:
> In article <957ghs$kl$1 AT news DOT onet DOT pl>, aiur9 <aiur9 AT kki DOT net DOT pl> wrote:
> >How can I get a structure member offset from inline assembly
>
> Who says it has to be assembly? Why not just take the address of
> fields in C, using the "&" operator?
>
> struct foo (
>     int x;
>     int y;
> }
>
> struct foo bar;
>
> long y_offset = &(bar.y) - &bar;
>
> Can't you make something like that work?
>
>
>
>

no
I want compiler to print y_offset in my piece of inline assembly code.
In above example i will get y_offset in variable and i.e instead of writing

asm(...
    mov <y_offset>(%%eax),%%edx
    ...)

I would have to write

asm(...
    mov _y_offset,%%eax
    mov <y_offset>(%%eax),%%edx
    ...)

see the difference

i tried something like this

asm(...
   "%0(%%eax),%%edx  \n"
    ...
    ::"m"(*(&some_struct.member-&some_struct)) /*this thing gives*/
                                               /*variable at offset of*/
                                               /*offset of member */
   );
but it won't work

- Raw text -