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From: yodaiken@freal.cs.umass.edu (victor yodaiken)
Newsgroups: comp.arch
Subject: self-modifying code
Message-ID: <5546@dime.cs.umass.edu>
Date: 12 Oct 89 14:50:34 GMT
Sender: news@dime.cs.umass.edu
Reply-To: yodaiken@freal.cs.umass.edu (victor yodaiken)
Organization: University of Massachusetts, Amherst
Lines: 17


Forget where I saw this nice example of self-modifying code. It was 
billed as one ofthe earliest mutual exclusion programs.


L: move opcode["branch to L"] to L
critical region
...
move opcode[" move opcode["branch to L"]] to L


The first programto execute the instruction at L changes the instruction
so that all others will just busy loop, and then changes it back
when it leaves the critical region
Of course it only works for uni-processors.

victor