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From: Blue Swirl <blauwirbel@gmail.com>
Date: Thu, 3 Sep 2009 21:10:40 +0300
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Subject: [Qemu-devel] Re: [Qemu-commits] [COMMIT 968a40f] microblaze: Trap
	on unaligned data accesses.
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To: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>

On Thu, Sep 3, 2009 at 2:11 PM, Anthony Liguori<aliguori@us.ibm.com> wrote:
> From: Edgar E. Iglesias <edgar.iglesias@gmail.com>

> +void helper_memalign(uint32_t addr, uint32_t dr, uint32_t wr, uint32_t s=
ize)
> +{
> + =C2=A0 =C2=A0uint32_t mask;
> +
> + =C2=A0 =C2=A0switch (size) {
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0case 4: mask =3D 3; break;
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0case 2: mask =3D 1; break;
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0default:
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0case 1: mask =3D 0; break;
> + =C2=A0 =C2=A0}

For additional performance (and to avoid the check for mask =3D=3D 0 case
;-)), you could perform most of the math above during translation.

Sparc32 actually avoids most of these explicit tests, but I still
can't understand Fabrice's magic that made it possible.