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From: ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University)
Newsgroups: comp.arch
Subject: What about loop instructions?
Message-ID: <1991Apr15.195511.3437@waikato.ac.nz>
Date: 15 Apr 91 07:55:11 GMT
Organization: University of Waikato, Hamilton, New Zealand
Lines: 17

What sort of looping instructions do different processors have?
I used to think it was more trouble than it was worth to use *any*
kind of "subtract-one-and-branch" instruction to implement a Pascal-style
for-loop correctly, until I saw some code which showed me the *right*
way to use the DBRA instruction on a 68000. I was impressed! This
instruction lets you handle an initial loop count of zero without a
separate check.

Do other architectures have loop instructions that are at least
as well-designed?

Lawrence D'Oliveiro                       fone: +64-71-562-889
Computer Services Dept                     fax: +64-71-384-066
University of Waikato            electric mail: ldo@waikato.ac.nz
Hamilton, New Zealand    37^ 47' 26" S, 175^ 19' 7" E, GMT+12:00
To someone with a hammer and a screwdriver, every problem looks
like a nail with threads.