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Date: Wed, 20 Apr 2011 11:37:17 +0200
From: Aurelien Jarno <aurelien@aurel32.net>
Message-ID: <20110420093717.GF6388@volta.aurel32.net>
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Subject: Re: [Qemu-devel] [PATCH 11/20] target-i386: fix helper_flbd_ST0()
 wrt softfloat
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org

On Tue, Apr 19, 2011 at 06:06:57PM +0100, Peter Maydell wrote:
> On 18 April 2011 22:00, Aurelien Jarno <aurelien@aurel32.net> wrote:
> > Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> > ---
> >  target-i386/op_helper.c |    7 ++++---
> >  1 files changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/target-i386/op_helper.c b/target-i386/op_helper.c
> > index f614893..7dddd37 100644
> > --- a/target-i386/op_helper.c
> > +++ b/target-i386/op_helper.c
> > @@ -3920,9 +3920,10 @@ void helper_fbld_ST0(target_ulong ptr)
> >         v = ldub(ptr + i);
> >         val = (val * 100) + ((v >> 4) * 10) + (v & 0xf);
> >     }
> > -    tmp = val;
> > -    if (ldub(ptr + 9) & 0x80)
> > -        tmp = -tmp;
> > +    if (ldub(ptr + 9) & 0x80) {
> > +        val = -val;
> > +    }
> > +    tmp = int64_to_floatx(val, &env->fp_status);
> >     fpush();
> >     ST0 = tmp;
> >  }
> 
> This doesn't do the right thing for -0 (should generate -0,
> not +0). I think:
> 
>  tmp = int64_to_floatx(val, &env->fp_status);
>  if (ldub(ptr + 9) & 0x80) {
>      floatx_chs(tmp);
>  }
> 
> ought to do the right thing and work for both softfloat and
> sf-native, but I haven't tested it.
> 

Good catch, this solution works. Thanks.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net