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Re: [Qemu-devel] [PATCH 2/4] softfloat: add float32_set_sign(), float32_
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 2/4] softfloat: add float32_set_sign(), float32_infinity, float64_half, float64_256 and float64_512. |
Date: |
Sun, 20 Feb 2011 23:20:33 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Sun, Feb 20, 2011 at 10:09:46PM +0000, Peter Maydell wrote:
> On 20 February 2011 21:52, Aurelien Jarno <address@hidden> wrote:
> > On Fri, Feb 18, 2011 at 03:49:15PM +0100, Christophe Lyon wrote:
>
> >> +#define float64_half make_float64(0x3fe0000000000000LL)
> >> +#define float64_256 make_float64(0x4070000000000000LL)
> >> +#define float64_512 make_float64(0x4080000000000000LL)
> >>
> >>
> >> /*----------------------------------------------------------------------------
> >> | The pattern for a default generated double-precision NaN.
> >
> > While it's probably a good idea to define the commonly used values in
> > softfloat.h, I don't think we should have all the values used by the
> > different targets here. Infinity, one, half, two probably have their
> > place here, I don't think it's the case of 256 and 512. It should be
> > better to defined them at the target level.
>
> Are you happy with targets just doing make_float*() on a
> bit pattern? I guess that's the most straightforward thing,
Yes, I think it is the way to go.
> although at the moment the target-arm code seems to prefer
> float32 three = int32_to_float32(3, s);
> I don't care very much personally as long as we're not doing
> a runtime division to get a constant 0.5 :-)
Doing that at runtime is clearly not a good solution.
> Incidentally, if you're up for some target-mips cleanup:
> target-mips/op_helper.c:#define FLOAT_ONE32 make_float32(0x3f8 << 20)
>
> could be using float32_one instead. (ditto for float64).
Yes, one is a really common value among target, and in my opinion we
should keep it in softfloat.h. I have a local patch that does this
cleanup and also moves the constant 2 to softfloat.h. I'll submit it one
day with other mips softfloat cleanup.
> > Also for consistency, I
> > think it's better to define these value for all float size, or at least
> > for all the common ones (32, 64, maybe 16).
>
> I wouldn't bother with 16, only ARM uses that and only for
> conversions to other formats.
>
That's true, so let's do it float 32 and 64.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- [Qemu-devel] [PATCH v4 0/4] ARM: fix Neon VRECPE and VRSQRTE instructions., Christophe Lyon, 2011/02/18
- [Qemu-devel] [PATCH 2/4] softfloat: add float32_set_sign(), float32_infinity, float64_half, float64_256 and float64_512., Christophe Lyon, 2011/02/18
- Re: [Qemu-devel] [PATCH 2/4] softfloat: add float32_set_sign(), float32_infinity, float64_half, float64_256 and float64_512., Aurelien Jarno, 2011/02/20
- Re: [Qemu-devel] [PATCH 2/4] softfloat: add float32_set_sign(), float32_infinity, float64_half, float64_256 and float64_512., Peter Maydell, 2011/02/20
- Re: [Qemu-devel] [PATCH 2/4] softfloat: add float32_set_sign(), float32_infinity, float64_half, float64_256 and float64_512.,
Aurelien Jarno <=
- Re: [Qemu-devel] [PATCH 2/4] softfloat: add float32_set_sign(), float32_infinity, float64_half, float64_256 and float64_512., Christophe Lyon, 2011/02/21
[Qemu-devel] [PATCH 3/4] target-arm: fix support for VRECPE., Christophe Lyon, 2011/02/18
[Qemu-devel] [PATCH 4/4] target-arm: fix support for VRSQRTE., Christophe Lyon, 2011/02/18
[Qemu-devel] [PATCH 1/4] softfloat: move all default NaN definitions to softfloat.h., Christophe Lyon, 2011/02/18