Path: utzoo!attcan!uunet!bu.edu!snorkelwacker!usc!wuarchive!udel!mmdf
From: kosma%human-torch@stc.lockheed.com (Monty Kosma)
Newsgroups: comp.sys.amiga
Subject: Whats wrong with self Modifying Code?
Message-ID: <24379@snow-white.udel.EDU>
Date: 12 Jul 90 19:20:53 GMT
Sender: mmdf@udel.EDU
Lines: 35


   From: Glenn Patrick Steffler <gpsteffl@sunee.waterloo.edu>
   Newsgroups: comp.sys.amiga.tech
   Keywords: religion, gurus, whats up?
   Date: 9 Jul 90 16:36:07 GMT
   Organization: Gerbils On Speed Inc.
   Sender: amiga-relay-request@udel.edu

   I have been waiting for people to show all of the great ways to avoid
   self modifying code.  But the examples have been contrived and not the
   least instructive.

   Lets take a real world example:

   A spread sheet program which must perform several thousand iterations
   of a formula while recalculating.  The formula can be "compiled" to
   the stack, and run such that the execution time is considerably less
   than if the formula had been interpreted each time.

   A video device driver or some such that uses raster ops to write values
   to the video display.  (Given the Amiga has a blitter with this ability
   I do not ask for confirmation of the relevance of this arguement)  The
   driver can "compile" a raster operation fill algorithm into some small
   code segment and run it.  This is indeed self modifying code, but is 
   almost essential for speed, because the user hates to wait for screen
   refresh.

   Anyway, that was just some fodder for you guys.  I submit this for
   rationalization or destruction.



I would think that these examples represent "code-generating" rather
than "code-modifying."  Why not just create the new code segments off in 
memory somewhere and then jump to that address?  Would that be illegal?