Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!decwrl!decvax!zinn!ditka!kls
From: kls@ditka.UUCP (Karl Swartz)
Newsgroups: comp.sys.nsc.32k
Subject: Re: Timing question
Message-ID: <3878@ditka.UUCP>
Date: 31 Aug 89 08:14:50 GMT
References: <13223@reed.UUCP>
Reply-To: kls@ditka.UUCP (Karl Swartz)
Organization: Inaction Central, Los Alamos, New Mexico
Lines: 22

In article <13223@reed.UUCP> bob@reed.UUCP (Bob Ankeney) writes:
>
>     A quick question:  Which (if either) is faster in execution:

According to my (ancient) manuals, for a 32032 ...

    movw foo(r1),bar(r1)		; 19 cycles
    movw foo[r1:b],bar[r1:b]		; 27 cycles

This assumes the source and destination words are aligned and there
are MMU delays (subtract 2 cycles from each case for no MMU).  Plus
there's the time to fetch an extra two bytes of instruction for the
the indexed case.

In other words, index mode is a loser where a simpler addressing
mode can be used, certainly in this case, and probably in all cases.

-- 
Karl Swartz		|UUCP		uunet!lll-winken!ames!hc!rt1!ditka!kls
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"I never let my schooling get in the way of my education."  (Twain)