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From: homeis@azu.informatik.uni-stuttgart.de (Dieter Homeister)
Newsgroups: comp.sys.transputer
Subject: Re: 16-bit Integers
Message-ID: <4104@ifi.informatik.uni-stuttgart.de>
Date: 17 Aug 90 18:10:27 GMT
Sender: news@ifistg.uucp
Organization: IPVR, Univ. Stuttgart, W-Germany
Lines: 28
Originator: homeis@azu


Markus Bohn writes:

>Has anyone experience or knowledge of transputer C-compilers with
>16 Bit Integer Dataformat ???

I had the same Problem. I needed 1024*768 pixel data and I have only
2 MB RAM, so I had to pack 2 16-bit-ints into one 32-bit int.
My c-compiler (developped by one of my students, Andreas Kaiser),
cannot handle 16-bit-ints on T414 or T800, too. Only for the T212 the
compiler can produce code for 16- and 32-bit-ints.
The reason is that the transputer does not support the handling of
16-bit-values on 32-bit-transputers, so the produced code is
very inefficient, no matter if a compiler or a programmer generates
it. For the programmer it might be more comfortable, if the compiler
does this job.
I tried two solutions: shift and mask, or moving two bytes.
To my surprise the shift solution was faster, so I now use this.
In my case efficiency of the 16-bit-access is not important, so I
didn't try register optimisation or asm parts.

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Dieter Homeister, Universitaet Stuttgart,
Institut fuer parallele und verteilte Hoechstleistungsrechner (IPVR)
7000 Stuttgart 1, Azenbergstr. 12, Tel 0711-121-1342, W-Germany
e-mail homeister@informatik.uni-stuttgart.dbp.de
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I'm a little bit tired, so put spelling errors > /dev/null