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From: "Martin v. Loewis" <martin@mira.isdn.cs.tu-berlin.de>
To: greened@eecs.umich.edu
Cc: egcs@egcs.cygnus.com
Subject: Re: egcs and bitfields
Date: Thu, 11 Mar 1999 15:14:00 -0000	[thread overview]
Message-ID: <199903112300.AAA19947@mira.isdn.cs.tu-berlin.de> (raw)
In-Reply-To: < 36E844B2.8DAEFAAF@eecs.umich.edu > (greened@eecs.umich.edu)

> I sent this question to the list a few days ago but got
> no response.  Can someone please help me out?

I think the problem with your previous report was that it was hard to
understand. I tried to come up with a program that demonstrates your
problem, and I got

struct baz { unsigned int a:2, b:4, c:32;} y;

void foo()
{
  y.c = 0x56789;
}

int main()
{
  unsigned int  *b;
  bzero(&y,sizeof(y));
  foo();
  b=&y;
  printf("%x %x\n",b[0],b[1]);
}

Is this the case you are talking about? Now, you claim that the SysV
ABI requires y.c to be at offset 4, right? (this is a claim I can't
verify since I don't have that specification)

Anyway, when I run the program on i586-pc-linux-gnu, with
egcs-2.93.11, I get as output

0 56789

From your explanation, I understand that this result is
ABI-compliant. So where is the problem?

Regards,
Martin

WARNING: multiple messages have this Message-ID

From: "Martin v. Loewis" <martin@mira.isdn.cs.tu-berlin.de>
To: greened@eecs.umich.edu
Cc: egcs@egcs.cygnus.com
Subject: Re: egcs and bitfields
Date: Wed, 31 Mar 1999 23:46:00 -0000	[thread overview]
Message-ID: <199903112300.AAA19947@mira.isdn.cs.tu-berlin.de> (raw)
Message-ID: <19990331234600.E1vbmECU0At5DgmufVNx0iMPUzToyIPYuEC3RsDSRcM@z> (raw)
In-Reply-To: <36E844B2.8DAEFAAF@eecs.umich.edu>

> I sent this question to the list a few days ago but got
> no response.  Can someone please help me out?

I think the problem with your previous report was that it was hard to
understand. I tried to come up with a program that demonstrates your
problem, and I got

struct baz { unsigned int a:2, b:4, c:32;} y;

void foo()
{
  y.c = 0x56789;
}

int main()
{
  unsigned int  *b;
  bzero(&y,sizeof(y));
  foo();
  b=&y;
  printf("%x %x\n",b[0],b[1]);
}

Is this the case you are talking about? Now, you claim that the SysV
ABI requires y.c to be at offset 4, right? (this is a claim I can't
verify since I don't have that specification)

Anyway, when I run the program on i586-pc-linux-gnu, with
egcs-2.93.11, I get as output

0 56789

From your explanation, I understand that this result is
ABI-compliant. So where is the problem?

Regards,
Martin

  parent reply	other threads:[~1999-03-11 15:14 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1999-03-11 14:33 David A. Greene
     [not found] ` < 36E844B2.8DAEFAAF@eecs.umich.edu >
1999-03-11 15:14   ` Martin v. Loewis [this message]
     [not found]     ` < 199903112300.AAA19947@mira.isdn.cs.tu-berlin.de >
1999-03-11 15:41       ` Robert Lipe
1999-03-31 23:46         ` Robert Lipe
1999-03-12  7:16     ` David A. Greene
     [not found]       ` < 36E92F61.5951621@eecs.umich.edu >
1999-03-12  8:48         ` Robert Lipe
     [not found]           ` < 19990312104540.D1570@rjlhome.sco.com >
1999-03-12  9:41             ` Doug Semler
     [not found]               ` < 199903121741.JAA24401@vortex.seaspace.com >
1999-03-12  9:59                 ` Robert Lipe
1999-03-31 23:46                   ` Robert Lipe
1999-03-12 13:26                 ` Martin v. Loewis
     [not found]                   ` < 199903122118.WAA00520@mira.isdn.cs.tu-berlin.de >
1999-03-12 13:52                     ` Doug Semler
1999-03-31 23:46                       ` Doug Semler
1999-03-31 23:46                   ` Martin v. Loewis
1999-03-31 23:46               ` Doug Semler
1999-03-31 23:46           ` Robert Lipe
1999-03-12  9:27         ` Martin v. Loewis
1999-03-12 10:47           ` David A. Greene
1999-03-31 23:46             ` David A. Greene
1999-03-31 23:46           ` Martin v. Loewis
1999-03-31 23:46       ` David A. Greene
1999-03-31 23:46     ` Martin v. Loewis
1999-03-31 23:46 ` David A. Greene
1999-03-12  7:20 David A. Greene
1999-03-31 23:46 ` David A. Greene

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