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Re: [Qemu-devel] [PATCH 0/9] tcg: reorganize bswap* functions
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 0/9] tcg: reorganize bswap* functions |
Date: |
Thu, 12 Mar 2009 14:37:36 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Thu, Mar 12, 2009 at 01:31:30PM +0000, Paul Brook wrote:
> > > I think we want to preserve the zero extension of the value, i.e. you
> > > want something along the lines of:
> > >
> > > if (!TCGV_EQUAL_I64(ret, arg))
> > > tcg_gen_movi_i32(TCGV_HIGH(ret), 0);
> >
> > That's why I have modified the documentation to say the high bytes have
> > to be zero, similar to the current bswap16_i32 implementation.
>
> There are two issues here:
>
> - Requiring a zero extended input value.
> - Providing a zero extended result.
>
> Your documentation covers the former requirement. However it does not
> mention
> the latter. The existing bswap16_i32 implementation does provide this
> guarantee (and can be simplified if we do not require this). I expect it is
> worth preserving the zero extension.
Thanks for your explanations, I see your point. I'll fix that before
committing the series.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- [Qemu-devel] [PATCH 5/9] tcg: update README wrt recent bswap changes, (continued)
- [Qemu-devel] [PATCH 5/9] tcg: update README wrt recent bswap changes, Aurelien Jarno, 2009/03/11
- [Qemu-devel] [PATCH 7/9] target-i386: use the new bswap* TCG ops, Aurelien Jarno, 2009/03/11
- [Qemu-devel] [PATCH 9/9] tcg/x86_64: add bswap16_i{32, 64} and bswap32_i64 ops, Aurelien Jarno, 2009/03/11
- [Qemu-devel] [PATCH 8/9] tcg/x86: add bswap16_i32 ops, Aurelien Jarno, 2009/03/11
- [Qemu-devel] [PATCH 3/9] tcg: add bswap16_i64 and bswap32_i64 TCG ops, Aurelien Jarno, 2009/03/11
- [Qemu-devel] [PATCH 6/9] target-ppc: use the new bswap* TCG ops, Aurelien Jarno, 2009/03/11
- [Qemu-devel] [PATCH 1/9] tcg: rename bswap_i32/i64 functions, Aurelien Jarno, 2009/03/11
- Re: [Qemu-devel] [PATCH 0/9] tcg: reorganize bswap* functions, Paul Brook, 2009/03/12