Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!dsinc!bagate!cbmvax!chrisg
From: chrisg@cbmvax.commodore.com (Chris Green)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Switching between integer and floating point
Message-ID: <20935@cbmvax.commodore.com>
Date: 25 Apr 91 13:47:47 GMT
References: <1991Apr24.041205.1588@netcom.COM>
Reply-To: chrisg@cbmvax.commodore.com (Chris Green)
Organization: Commodore, West Chester, PA
Lines: 27

In article <1991Apr24.041205.1588@netcom.COM> rodent@netcom.COM (Ben Discoe) writes:
>
>  I've been working on a 3D object viewer intended for PD release, with
>source, as soon as it's stable.  My problem is this: when the project was
>started, I only had a 1000 to work on, so I wrote all the math using
>two kinds of fixed-point integer math (one kind for angles, another for
>coordinates).
>  Now I (and many people who may want the code) are on accelerated
>systems with 6888x's, so I'd like to include a compile-time flag to
>compile with floating-point math instead of the integers.  I'm sure many
>other people have faced this same problem: how do you keep one source
>with two different kinds of math involved?

	Unless you have precision problems with your fixed point, you'd be better
off keeping it, even on a 68882 system, since it will still be faster.
	A far better option for people with 020's and 030's is keeping the fixed
point, but going to 32 bit precision, and using the 32x32->64 multiply
and 64/32->32:32 divide instructions available on these processors.


-- 
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|Chris Green - Graphics Software Engineer   - chrisg@commodore.COM      f
|                  Commodore-Amiga          - uunet!cbmvax!chrisg       n
|My opinions are my own, and do not         - killyouridolssonicdeath   o
|necessarily represent those of my employer.- itstheendoftheworld       r
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