Reply-To: <arfa AT clara DOT net>
From: "Arthur" <arfa AT clara DOT net>
To: "DJGPP Mailing List" <djgpp AT delorie DOT com>
Subject: RE: Floating/fixed point
Date: Thu, 17 Sep 1998 16:25:14 +0100
Message-ID: <000201bde24f$5e1d1560$a14e08c3@arthur>
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> > Are you sure you're using the FPU? Are you sure you're using a genuine
> > Intel? Besides, the real difference is in multiplications, divisions and
> > trigonomic functions, which are quite a bit faster than integer
> math on a
> > standard Pentium. On a PII, the FPU is generally the same as a
> Pentium, but
> > integer math is improved quite a bit over a Pentium.
> 	I am using a Genuine Pentium 150 (Classic).  And floating
> point operations
> take much longer than integer.  I think it is about 5 times slower for
> floating point stuff.  A floating point multiply takes about the
> same time as
> a floating point add, so if fadd's were as fast as add's then
> fmul's would be
> significantly faster than mul's.  And everyone would use fmul's!!

I'll have to see your benchmark code to be convinced. Float-integer
conversion is very slow, as are if() statements. So no, people wouldn't use
fmul instead of mul.

Make sure you've told DJGPP to use the FPU (can't remember if it does this
by default - I havn't used floats for ages).

James Arthur
jaa AT arfa DOT clara DOT net
ICQ#15054819