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Re: math-emu issue with fp divide



On Jun 12, 2008, at 11:24 PM, David Miller wrote:


From: Kumar Gala <galak@kernel.crashing.org>
Date: Thu, 5 Jun 2008 08:38:44 -0500 (CDT)

Now that I'm digging into this a bit I'm thinking my issue has to do with
the fix you put in place from back in Aug 2007 (commit
405849610fd96b4f34cd1875c4c033228fea6c0f):


[MATH-EMU]: Fix underflow exception reporting.

   2) we ended up rounding back up to normal (this is the case where
      we set the exponent to 1 and set the fraction to zero), this
      should set inexact too
...

Another example, "0x0.0000000000001p-1022 / 16.0", should signal both
inexact and underflow. The cpu implementations and ieee1754
literature is very clear about this. This is case #2 above.


I'm not clear from your commit comment on what actual number
0x0.0....01p-1022 is?

I haven't been able to look closely at this yet but I think I happened to stumble over the test case that lead me to that changeset you are referencing here.

Have you had a chance to look at this?


- k


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