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From: peter@ficc.uu.net (Peter da Silva)
Newsgroups: comp.arch,comp.lang.misc
Subject: Re: Double Width Integer Multiplication and Division
Message-ID: <4909@ficc.uu.net>
Date: 7 Jul 89 15:02:24 GMT
References: <57125@linus.UUCP> <1989Jun24.230056.27774@utzoo.uucp> <1388@l.cc.purdue.edu>
Organization: Xenix Support, FICC
Lines: 27

In article <1388@l.cc.purdue.edu>, cik@l.cc.purdue.edu (Herman Rubin) writes:
> For example, on a machine in which there is division yielding a quotient
> and a remainder, I want to write

> 	q,r = x/y;

(1) What does this do when no such operation exists?
(2) How does this fit in with the rest of the expression syntax?
(3) Get a good optimiser and say:
	q = x/y;
	r = x%y;
(4) Is it obvious which is the quotient and which is the remainder
    when you have something like:
	tens,relx = muscle0.fiber/potential;
(5) What if x or y contain other operations that could require a
    quotient or remainder?
(6) What does this mean:
	q,r,s = x/y/z;
(7) What does this sort of micro-optimisation gain you? Except in a
    tight loop, very little. Since you're intending to be machine-
    specific anyway, why not squirrel that loop away in an assembly
    routine?
-- 
Peter da Silva, Xenix Support, Ferranti International Controls Corporation.
Business: peter@ficc.uu.net, +1 713 274 5180. | "WHAT HAPPENED TO ALL
Personal: peter@sugar.hackercorp.com.   `-_-' |  THE WOMEN IN TEXAS?"
Quote: Have you hugged your wolf today?  'U`  |  -- ACS1W@jane.uh.edu (meesh)