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Text File  |  1992-07-20  |  973 b   |  33 lines
  1. Newsgroups: comp.sys.m68k
  2. Path: sparky!uunet!munnari.oz.au!newsroom.utas.edu.au!bruny.cc.utas.edu.au!u882453
  3. From: u882453@bruny.cc.utas.edu.au (Andrew King)
  4. Subject: Re: 4 byte fetch...
  5. Message-ID: <u882453.711698745@bruny>
  6. Sender: news@newsroom.utas.edu.au
  7. Organization: University of Tasmania, Australia.
  8. References: <1992Jul8.160456.22056@col.hp.com> <0ZqoNB1w164w@PDaXcess.techbook.com> <ERIC.92Jul10143833@iceland.telebit.com>
  9. Date: Tue, 21 Jul 1992 06:05:45 GMT
  10. Lines: 21
  11.  
  12. eric@telebit.com (Eric Smith) writes:
  13.  
  14. >If the intent is to obfuscate the code, wouldn't it be better to modify the
  15. >code as far away from the modified code as possible?
  16.  
  17. >Instead of:
  18. >                move.w  d0,(a0)
  19. >                jmp     (a6)
  20.  
  21. >You would use:
  22. >                move.w  d0,(a0)
  23. >... do lots of stuff here...
  24. >                jmp     (a6)
  25.  
  26. Another trick is to use:
  27.         move.l    a6,(a7)
  28. .... do lots of code here
  29.         rts
  30.  
  31. Trace vector-decoders are often used to protect code too..
  32.  
  33.