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From: graeme@labtam.labtam.oz (Graeme Gill)
Newsgroups: comp.arch
Subject: Re: MIPS, Compaq and Microsoft in bed - NYT story
Message-ID: <5974@labtam.labtam.oz>
Date: 14 Feb 91 01:11:51 GMT
References: <29920@usc> <45758@mips.mips.COM> <3188@crdos1.crd.ge.COM>
Organization: Labtam Australia, Melbourne, Australia
Lines: 18

In article <3188@crdos1.crd.ge.COM>, davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr) writes:
> 
>   Since all you can portable do in C is add or subtract ints and
> pointers, or subtract pointers, you don't need the rest of the
> arithmetic, except to do vastly unportable things. Portable programs
> don't AND or XOR stuff into pointers, nor assume that their high or low
> bits are available for flags.
> 

	Just a small point, but a lot of these machines have memory alignment
restrictions. How do you ensure address alignment if you can't do an
AND on an address ?  Isn't being able to do integer arithmetic on addresses
the more general solution to testing alignment and calculating structure/array
addresses ? (I am refering here to machine level rather than language level
facilities).

	Graeme Gill
	Labtam Australia