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Re: [Qemu-devel] [PATCH 2/4] target-arm: Fix implementation of VRSQRTS
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 2/4] target-arm: Fix implementation of VRSQRTS |
Date: |
Mon, 10 Jan 2011 20:20:39 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Fri, Jan 07, 2011 at 09:26:25AM +0000, Peter Maydell wrote:
> The implementation of the ARM VRSQRTS instruction (which calculates
> (3 - op1 * op2) / 2) was missing the division operation. It also
> did not handle the special cases of (0,inf) and (inf,0).
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> target-arm/helper.c | 10 +++++++++-
> 1 files changed, 9 insertions(+), 1 deletions(-)
Reviewed-by: Aurelien Jarno <address@hidden>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 705b99f..ac47de0 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -2612,8 +2612,16 @@ float32 HELPER(recps_f32)(float32 a, float32 b,
> CPUState *env)
> float32 HELPER(rsqrts_f32)(float32 a, float32 b, CPUState *env)
> {
> float_status *s = &env->vfp.fp_status;
> + float32 two = int32_to_float32(2, s);
> float32 three = int32_to_float32(3, s);
> - return float32_sub(three, float32_mul(a, b, s), s);
> + float32 product;
> + if ((float32_is_infinity(a) && float32_is_zero_or_denormal(b)) ||
> + (float32_is_infinity(b) && float32_is_zero_or_denormal(a))) {
> + product = float32_zero;
> + } else {
> + product = float32_mul(a, b, s);
> + }
> + return float32_div(float32_sub(three, product, s), two, s);
> }
>
> /* NEON helpers. */
> --
> 1.6.3.3
>
>
>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- [Qemu-devel] [PATCH 0/4] target-arm: Fix VRSQRTS, Peter Maydell, 2011/01/07
- [Qemu-devel] [PATCH 3/4] target-arm: Add support for 'Standard FPSCR Value' as used by Neon, Peter Maydell, 2011/01/07
- [Qemu-devel] [PATCH 2/4] target-arm: Fix implementation of VRSQRTS, Peter Maydell, 2011/01/07
- Re: [Qemu-devel] [PATCH 2/4] target-arm: Fix implementation of VRSQRTS,
Aurelien Jarno <=
- [Qemu-devel] [PATCH 1/4] softfloat: Add float32_is_zero_or_denormal() function, Peter Maydell, 2011/01/07
- [Qemu-devel] [PATCH 4/4] target-arm: Use the standard FPSCR value for VRSQRTS, Peter Maydell, 2011/01/07
- Re: [Qemu-devel] [PATCH 0/4] target-arm: Fix VRSQRTS, Aurelien Jarno, 2011/01/14