Subject: Freeze-x! and "Oh no, yet another bug"
From: stst@vuse.vanderbilt.edu (Stefan Strack)
Organization: Vanderbilt University School of Engineering, Nashville, TN, USA
Date: 19 Feb 92 03:22:08 GMT
Message-ID: <1992Feb19.032208.22621@vuse.vanderbilt.edu>


In our series of somewhat successful KotH warriors, here's Freeze-x!
Optimized to beat CLONER II on the -x hill, Freeze-x! does well against
mice-type programs in general. The program scans for non-zero B-fields
and drops a JMP 0 bomb there to paralyze. When the bomb is re-encountered
on the next sweep (or any address with BVal=1), Freeze-x! switches to
kill-mode and drops DAT 0's.

;redcode-x
;name Freeze-x!
;author Stefan Strack
;strategy Bomb with JMP 0, then with DAT 0
;strategy Submitted: @date@

dist    equ     211
scanptr equ     (scan-3)

scan    add     #dist+1,scanptr    ; simple imptrap
        jmz     scan,   <scanptr
        slt     #bomb-scanptr,scanptr
        jmp     scan
        slt     #1,     @scanptr   ; is this a bomb?
        mov     bomb+1, bomb
        mov     bomb,   @scanptr
        jmp     scan
bomb    jmp     bomb,   #1

        end     scan

On the topic of bug-reports: I've received a couple of inquiries as to
why the DOS-port of KotH corewar sometimes aborts with the message
"Out of memory creating new thread". DOS memory constraints put a limit
to the maximum number of threads a program can spawn off. This limit
is significantly lower than the KotH default of 8000 (ca. 700 for the
standard hill, half that for the experimental). If koth.exe aborts,
rerun the game with a smaller thread maximum using the "-maxprocs nnn"
switch.

Just to prevent the imminent "A huge, nasty bug" post ...  :-)

-Stefan (stst@vuse.vanderbilt.edu)