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[Qemu-devel] Re: [PATCH 1/3] PPC: Circumvent overflow in mtcrf


From: Blue Swirl
Subject: [Qemu-devel] Re: [PATCH 1/3] PPC: Circumvent overflow in mtcrf
Date: Mon, 2 Mar 2009 20:53:35 +0200

On 3/2/09, Alexander Graf <address@hidden> wrote:
> I had a segmentation fault in mtcrf, where ffs() returned 8 and the
>  code then accessed cpu_crf[7 - 8].
>
>  In order to circumvent this, I just put in an & 7 to the ffs result,
>  so we'll never run negative. This is probably not correct, but makes
>  things work for me so far.

ffs does not return bit number (in power of 2 numbering), but one if
the zeroth bit is set, two if the first bit is set etc. So I'd try
instead

crn = ffs(crm) - 1;




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