Article View: rec.games.corewar
Article #184Re: Decrement Protection
From: pk6811s
Date: Thu, 08 Oct 1992 20:13
Date: Thu, 08 Oct 1992 20:13
46 lines
2207 bytes
2207 bytes
>
> Here is my program SNAKE. All of my vampiric bombers kept taking
> a beating from this new class of bombers that claim to bomb
> the core at 150% of c. But a decrement doesn't kill a program.
> I designed all of the B-fields so that if any one is decremented,
> the bombing routine keeps functioning.
>
> I would really be interested in any other programs that use
> this tactic.
AhHa! So that's why Snake does so well against my bombers.
I wondered if people would catch on to this. It's easy to protect
against single decrements on b-fields. Here's how I do it in Eclipse:
Lines marked ** function normally when decremented (once).
;redcode
;name Eclipse V2.0
;kill Eclipse
;author P.Kline
;strategy bscan, 2-dwarf, 1-dwarf
bomb2 mov -1,<0
ptr mov bomb1,<1-131
next add #121,@2 ; **
jmz next,@ptr
mov bomb2,@ptr
jmn ptr,@-1 ; **
bomb1 spl 0,10 ; **
mov cnt+1,<bomb1-2 ; **
mov cnt+3,<bomb1-3 ; **
cnt djn -1,@0 ; ** stays zero until decremented or executed
end next
Here's another tip. Don't put zeros in any b-fields in your code.
Since the bomber is doing:
mov <a,<b
if a points to your zero-value, no problem, but if b does,
the location just ahead of it will be bombed. Better to make it
something large. This also applies to locations following your
code. Better make them something other than zero too.
Course that leaves you open to probing by b-scanners . . .
Unfortunately, all this anti-stone technology is only going to help scanners.
Paul Kline
pk6811s@acad.drake.edu
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Newsgroups: rec.games.corewar Path: arc1-ca.pugleaf.net!sparky!uunet!europa.asd.contel.com!darwin.sura.net!zaphod.mps.ohio-state.edu!sdd.hp.com!ux1.cso.uiuc.edu!news.iastate.edu!dunix.drake.edu!acad.drake.edu!pk6811s From: pk6811s@acad.drake.edu Subject: Re: Decrement Protection Message-ID: <1992Oct8.141307.1@acad.drake.edu> Lines: 46 Sender: news@dunix.drake.edu (USENET News System) Nntp-Posting-Host: acad.drake.edu Organization: Drake University, Des Moines, Iowa, USA References: <70423@hydra.gatech.EDU> Date: Thu, 8 Oct 1992 20:13:07 GMT