cvs commit: src/sys/ia64/include float.h
marcel at xcllnt.net
Wed Apr 2 13:07:17 PST 2003
On Wed, Apr 02, 2003 at 09:19:21PM +1000, Bruce Evans wrote:
> On Wed, 2 Apr 2003, Peter Jeremy wrote:
> > On Wed, Apr 02, 2003 at 04:21:30PM +1000, Bruce Evans wrote:
> > >On Wed, 2 Apr 2003, Peter Jeremy wrote:
> > >
> > >> On Tue, Apr 01, 2003 at 05:24:40PM +0200, Alexander Leidinger wrote:
> > >> >We noticed that icc does use other values for LDBL_MIN than we do, and
> > >> >instead of just thinking that Intel does it right I wanted to verify it.
> > >
> > >This might be caused by icc actually understanding the target's default
> > >precision for long doubles (FreeBSD changes the hardware default of 64-bit
> > >to 53-bit for technical reasons).
> > Is this also true on ia64?
> Probably not. ia64's _fpmath.h says that there are 64 mantissa bits,
> and we don't reduce the precision AFAIK.
Correct. Note that the 64-bit significand includes an explicit integer
bit. The binary point is assumed to be between bits 62 and 63.
Note also that the 82-bit FP registers have a 17-bit exponent to aid
in near-overflow and near-underflow computations in IEEE754 double-
extended format. Of course an exception is still raised if the result
does not fit the target if the target is in double-extended format.
Marcel Moolenaar USPA: A-39004 marcel at xcllnt.net
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