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Re: [Qemu-devel] [PATCH] target-ppc: fix nego and subf*o instructions
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From: |
Richard Henderson |
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Subject: |
Re: [Qemu-devel] [PATCH] target-ppc: fix nego and subf*o instructions |
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Date: |
Sun, 31 Mar 2013 18:15:14 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
On 03/31/2013 04:50 PM, Peter Maydell wrote:
>> > I'm a bit confused. This is the exact same algorithm that's used on ARM
>> > and
>> > i386. And as far as I can determine, all three platforms have the same
>> > definition of "overflow".
> I think it's not quite the same as ARM because the two arguments
> to subtract are reversed for PPC (ie PPC is 'subtract from', not
> 'subtract'). I think that means you want 'xor_tl(cpu_ov, arg0, arg2)'
> for your first xor, maybe? (untested)
Oh, duh. Of course.
r~