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From: dvljrt@cs.umu.se (Joakim Rosqvist)
Newsgroups: comp.sys.amiga.programmer
Subject: Self modifying code
Message-ID: <1991May28.120630.10150@cs.umu.se>
Date: 28 May 91 12:06:30 GMT
References: <5005@orbit.cts.com>
Sender: news@cs.umu.se (News Administrator)
Organization: Dep. of Info.Proc, Umea Univ., Sweden
Lines: 25

Ok, I have heard before that you should not use self modifying code.
Can anybody give a good reason for this, besides it being bad programming
pratice. 
I just got the RKM manuals and they only stated "for compatibilty with
010/020/030 etc. don't use selfmodifying code"
Could it be that data written to an address that is also in cachememory
will update the memory, but not the cache?

Consider for instance that I would like to write a fast completely
unwinded linedrawing routine and wrote code for drawing one pixel.
Then when the program start, I would allocate memory for 320 such routines
and putting 320 copies of my routine there. Would this be considered as
selfmodifying code, and therefore forbidden?

If so, compare it to when the OS is loading a program that contains
non-PC relative references to itself which will have to be rewritten
depending on the address the code was loaded to.



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