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From: "Brian R. Hanson" <brh@cray.com>
Subject: Re: Portability of Arithmetic (was: Java vs Ada 95)
Date: 1996/10/18
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Date: 1996-10-18T00:00:00+00:00
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Robert Dewar wrote:
> 
> iNorman says
> 
> "Harrumph! What about 64-bit UNsigned binary arithmetic?  32-bit
> arithmetic does not suffice for manipulating offsets into files larger
> than 4GB, or for calculating the amount of space available on some
> disks, or for timestamps accurate to the nearest millisecond and
> spanning a range of 16 months or more."
> 
> Well if you are telling me that you have written applications that
> do all the above, interesting ... I sure have not seen many such uses
> in the user code I have seen.
> 
> I am particularly interested in your comments on manipulating offsets
> into files larger than 4GB, what operating system are you talking about
> here for interest :-)

I work on an application that regularly needs to manipulate file offsets 
that do not fit in 32 bits.  Two systems that can handle this are

Cray Research Unicos 
Silicon Graphics Irix 6.2

I worked at Control Data on Nos/VE which provided a user address space
of
2**16 segments of 2**31 bytes.  Unfortunately, because files were always 
memory mapped, any one file could not exceed 2**31 bytes and the
commercial
database people were on our case for having such a pathetic limitation
for
file size.  This was 8 years ago at least.

Database applications and video applications I would expect would
consider 
4GB extreemly limiting.

-- Brian Hanson
-- brh@cray.com