On Apr 25, 2006, at 5:24 PM, Hollis Blanchard wrote:
On Tue, 2006-04-25 at 16:54 -0400, Jimi Xenidis wrote:
On Apr 25, 2006, at 4:08 PM, Hollis Blanchard wrote:
it is explained in the rest of the comment:
- FPSCR should be save/restored with stfd/lfd since the 32 bit
form
can mangle the value.
I read that; I still don't get it. If FPSCR is 32 bits, as all
available
documentation claims, then couldn't you use stfiwx?
Yes, the FPSCR _is_ 32bits (I never claimed it was not) however the
only way to store it is thru an FPR which is 64 bits.
We used to use lwfs/stfs but they convert from single to double
respectively doing who-knows-what to the actual value.
It is possible to use stfiwx but there is no "load form" to match it
(that I could see) and we would have to perform a full lfd for the
restore thereby "forcing" us to use a 64bit quantity. So I chose stf
and ldf purely for symmetry.
Your comment, on the other hand, claims it is 64 bits, and if that's
true then you wouldn't use stfiwx. However, in that case, I'd like to
know why you think it's 64 bits.
I used the word "quantities" to refer to storage rather that the
register itself.
[ Actually, I'm just being a a smart-ass there :-) ]
-JX
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