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Re: [PATCH] Fix absd emulation

To: Raghu Gandham <raghu@mips.com>
Subject: Re: [PATCH] Fix absd emulation
From: Ralf Baechle <ralf@linux-mips.org>
Date: Mon, 12 Oct 2009 18:15:56 +0200
Cc: linux-mips@linux-mips.org, chris@mips.com
In-reply-to: <20090710085057.25841.33067.stgit@linux-raghu>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20090710085057.25841.33067.stgit@linux-raghu>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.19 (2009-01-05)
On Fri, Jul 10, 2009 at 01:50:58AM -0700, Raghu Gandham wrote:

> From: Robin Randhawa <robin@mips.com>
> 
> Signed-off-by: Chris Dearman <chris@mips.com>
> ---
> 
>  arch/mips/math-emu/dp_simple.c |   11 ++++-------
>  arch/mips/math-emu/sp_simple.c |    3 ---
>  2 files changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/mips/math-emu/dp_simple.c b/arch/mips/math-emu/dp_simple.c
> index 1c555e6..6ff4655 100644
> --- a/arch/mips/math-emu/dp_simple.c
> +++ b/arch/mips/math-emu/dp_simple.c
> @@ -76,15 +76,12 @@ ieee754dp ieee754dp_abs(ieee754dp x)
>       CLEARCX;
>       FLUSHXDP;
>  
> +     /* Clear sign ALWAYS, irrespective of NaN */
> +     DPSIGN(x) = 0;
> +
>       if (xc == IEEE754_CLASS_SNAN) {
>               SETCX(IEEE754_INVALID_OPERATION);
> -             return ieee754dp_nanxcpt(ieee754dp_indef(), "neg");
> +             return ieee754dp_nanxcpt(ieee754dp_indef(), "abs");
>       }
> -
> -     if (ieee754dp_isnan(x)) /* but not infinity */
> -             return ieee754dp_nanxcpt(x, "abs", x);
> -
> -     /* quick fix up */
> -     DPSIGN(x) = 0;
>       return x;
>  }

It seems that abs.s needs the same changes except the string constant.  Or
why was only abs.d changed?

(And what is the official behaviour anyway.  It seems I can spend another
quality night over IEEE 754 ...)

> diff --git a/arch/mips/math-emu/sp_simple.c b/arch/mips/math-emu/sp_simple.c
> index 770f0f4..cdec1a2 100644
> --- a/arch/mips/math-emu/sp_simple.c
> +++ b/arch/mips/math-emu/sp_simple.c
> @@ -61,9 +61,6 @@ ieee754sp ieee754sp_neg(ieee754sp x)
>               SPSIGN(y) = SPSIGN(x);
>               return ieee754sp_nanxcpt(y, "neg");
>       }
> -
> -     if (ieee754sp_isnan(x)) /* but not infinity */
> -             return ieee754sp_nanxcpt(x, "neg", x);
>       return x;
>  }

The subject of the patch was claiming a fix to abs.d but this is fiddling
with neg.s.  And why not the equivalent change to neg.d?

  Ralf

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