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Date: Wed, 4 May 2005 23:57:30 +0200
From: Marc Olzheim <marcolz@stack.nl>
To: Daniel Eischen <deischen@freebsd.org>
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cc: Marc Olzheim <marcolz@stack.nl>
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Subject: Re: Floating point exceptions with -pthread
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On Wed, May 04, 2005 at 05:25:04PM -0400, Daniel Eischen wrote:
> floorf() seems to fiddle with the FP control word.  The kernel
> and libpthread use fxsave and fxrstor respectively.  These
> save and restore the control word, but something may not be
> working correctly.

Hmm, as does ceilf. But trunf() the only other doing this, does not
get the sigFPE:

fstcw, then:

floorf()     ceilf()      truncf()
or  0x0400   or  0x0800   or 0x0c00
and 0xf7ff   and 0xfbff

and fldcw the modified version.

Then why is truncf() different... ? All abuse the 0x0c00 bits of the
control word.

Marc

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