Article View: comp.arch
Article #2529Re: Self-modifying code
From: John Hascall
Date: Wed, 11 Oct 1989 22:12
Date: Wed, 11 Oct 1989 22:12
31 lines
1447 bytes
1447 bytes
In article <9175@etana.tut.fi> pl@etana.tut.fi (Lehtinen Pertti) writes:
}From article <6481@pt.cs.cmu.edu>, by koopman@a.gp.cs.cmu.edu (Philip Koopman):
} I've been lately wondering if there is any architecture
} with possibility to execute instruction indirectly.
} I mean something like:
}
} exec (r0) ; execute instruction pointed by r0
} Does anyone know?
Well, how about the IBM 370 series. (not exactly modern, I know)
If I recall correctly:
EX mask,location
<next instruction>
location: <target instruction>
Fetches the target instruction at "location" and ORs "mask" with
(some of) the target instruction and then executes the resulting
instruction. Control resumes at "next instruction".
The EX instruction is used all the time as
it is the only decent way to do a number of things.
John Hascall
ISU Comp Center
Technical Details
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<1619@atanasoff.cs.iastate.edu>Path:
arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!ginosko!uunet!deimos.cis.ksu.edu!atanasoff!hascallReferences:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!ginosko!uunet!deimos.cis.ksu.edu!atanasoff!hascall From: hascall@atanasoff.cs.iastate.edu (John Hascall) Newsgroups: comp.arch Subject: Re: Self-modifying code Message-ID: <1619@atanasoff.cs.iastate.edu> Date: 11 Oct 89 22:12:17 GMT References: <6481@pt.cs.cmu.edu> <9175@etana.tut.fi> Reply-To: hascall@atanasoff.UUCP (John Hascall) Organization: Iowa State Univ. Computation Center Lines: 31