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From: jpl@allegra.UUCP (John P. Linderman)
Newsgroups: net.unix,net.lang.c
Subject: Re: Portablity using structures and malloc - Help
Message-ID: <4772@allegra.UUCP>
Date: Sat, 20-Jul-85 13:21:09 EDT
Article-I.D.: allegra.4772
Posted: Sat Jul 20 13:21:09 1985
Date-Received: Sun, 21-Jul-85 22:05:25 EDT
References: <81@drux1.UUCP> <907@umcp-cs.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
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Xref: linus net.unix:4500 net.lang.c:5171

> The answer is simple: malloc has been written by someone who knows
> the hardware alignment constraints of the machine, and it returns
> a pointer that is aligned for *any* use.
> 
> In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)

malloc knows, but it's a pity that you can't make malloc tell.
If there were a nice

    int malign() {return ALIGNMENT_MULTIPLE;}

entry in the malloc package, I could do my own storage allocation out
of an area acquired from malloc or elsewhere.  [I might want to do this
so I could allocate variable-length structures from both ends of an area
until the area was filled, something malloc itself cannot be made to do.]
A totally trivial one-liner that would make it much easier to write
portable software.  How about it, system implementors?

John P. Linderman     The much-maligned allegra!jpl