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From: mjd@doc.ic.ac.uk (Martin J Davies)
Newsgroups: comp.sys.nsc.32k
Subject: Re: cxp/rxp instructions
Message-ID: <486@ivax.doc.ic.ac.uk>
Date: Sun, 19-Jul-87 08:41:33 EDT
Article-I.D.: ivax.486
Posted: Sun Jul 19 08:41:33 1987
Date-Received: Fri, 24-Jul-87 01:43:58 EDT
References: <1439@tekchips.TEK.COM>
Reply-To: winterbo@kcl-cs.UUCP
Organization: Dept. of Computing, Imperial College, London, UK.
Lines: 16
Keywords: Shared libraries


>
>>1) What good are the cxp/rxp instructions?...
>>The reason I ask is that evern cxp/rxp causes the 32xxx to read
>>from the mod table and I can see this as slowing things down A LOT.
>
>These instructions support shared libraries.  Yes, they are somewhat slower than jsr/ret, but they are MUCH faster than doing shared library calls in software!

	I have implemented shared 'C' libraries on a 32016 machine running my
own multi-user/multitasking o/s. I started using the RXP/CXP instructions
and this went quite well but there was a speed penalty. I found it much faster
to dynamicly link the library calls using an interrupt linkage handler. How
this could be applied to unix I am not sure, but modules do seem to use a
noticable amount of cpu time.

Posted on for P.Winterbottom Kings College London (Gemini Project)