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Re: [PATCH] Remove GMP in favor of MPFR
- From: Feng Wang <wf_cs at yahoo dot com>
- To: Richard Henderson <rth at redhat dot com>, Tim Prince <tprince at computer dot org>
- Cc: Paul Brook <paul at codesourcery dot com>, gcc-patches at gcc dot gnu dot org, Steve Kargl <sgk at troutmask dot apl dot washington dot edu>, fortran at gcc dot gnu dot org
- Date: Mon, 5 Jul 2004 11:43:04 +0800 (CST)
- Subject: Re: [PATCH] Remove GMP in favor of MPFR
--- Richard Henderson <rth@redhat.com> 的正文：> On Sun, Jul 04, 2004 at
10:57:26AM -0700, Tim Prince wrote:
> > > /* Recall that IEEE numbers are interpreted as 1.F x 2**exp,
> > > whereas the intermediate representation is 0.F x 2**exp.
> >
> > That should be 0.5F x 2**exp
>
> No, the "1" is implicit in the IEEE format. There is no implicit
> bit in the real.c representation. Thus "0.F" is correct.
It's the same with fortran.
In fact, IEEE just describes the storing format of floating point. 8 bits hold
the binary exponent with the range [-126, 127](normalized). In normalized form,
there is an implicit '1' in the fraction. Fortran uses "0.F x 2**e" REAL
concept model. The exponent range should be [-125,128].
Feng Wang
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