[Libre-soc-dev] [OpenPOWER-HDL-Cores] mulhw / mulhwu in microwatt updates SO

Paul Mackerras paulus at ozlabs.org
Sat Aug 29 01:08:31 BST 2020


Correcting myself:

On Sat, Aug 29, 2020 at 10:05:58AM +1000, Paul Mackerras wrote:

> Note that the write to XERC at 3445ns is the result of the previous
> instruction at 10358, which is "sraw.", which writes XER[CA].  The
> mulhw. at 1035c writes back at 3495ns, and we see it writing to CR0
> and GPR 1E (r30) but not XER.  It writes "5" i.e. binary 0101 to CR0,

It writes "9", binary 1001, I mean.

> so CR0[SO] is being set (correctly, since XER[SO] was set when the
> mulhw. started).

And this statement is correct.

Paul.



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