nanoWarrior #03

The latest issue of nanoWarrior has finally been completed, containing articles by John Metcalf, German Labarga and me. Check it out for yourself here:

http://corewar.co.uk/nw/nw03.txt

Neo's Mini Challenge - Roy's Idea

Roy suggested a tricky extension to Neo's Mini Challenge in rec.games.corewar:

Lets try to find a solution for this gate:
djn.f #0,>-5
(I haven't got one yet)

It appears a one instruction solution isn't possible. However, 5 players found a solution in two instructions.  Congratulations to Ilmari, John, Rashnok, Roy and me! Also, well done to German and Lukasz who also discovered solutions, albeit slightly longer.

I discovered a five line imp:

imp mov.i #4,   *1
    mov.i #4,   *1
    mov.i #4,   *1
    mov.i #4,   *1
    mov.i #4,   *1

By adding a loop, I managed to reduce the initial size to two instructions:

imp mov.i #4,   *1
    djn.a imp,  #0

John and Rashnok discovered the same 3 line imp and used a loop to reduce the size. Ilmari discovered a 2 line imp. Roy wrote a program to find 58 solutions by brute force!

Full details are on Neo's page for the Harmless Overrun Mini Challenge.

Thoughts on Corewar...

Thoughts on Corewar is John Metcalf's Redcode programming blog, hosted at http://impomatic.blogspot.com. Since John's blog was last reviewed, both the name and design have changed.

The standard template has gone and the sidebar now contains a selection of useful rss feeds, including the latest posts from rec.games.corewar and the most recent additions to the infinite nano and tiny hills.

The most interesting recent posts have been about Semaphores in Redcode, which provide a means of implementing mutual exclusing in Corewar.

What I liked:

• Covers advanced programming topics
• The feeds make it easy to keep up-to-date

Room for improvement:

• More comments on the code would be handy

tiny Twilight

Here's the code for Twilight, my most successful tiny warrior so far. When this entered SAL's tiny hill in 24th place two years ago, I didn't expect it to last long!

I'm surprised to see it's still on the tiny hill age 79. Currently it's in 10th place, the best position to date :)

;redcode-tiny
;name Twilight
;author S.Fernandes
;strategy oneshot v1

;assert CORESIZE == 800

; entered the hill on 12 Mar 2006 in 24th place
; still on the hill on 31 Oct 2008, age 79, 10th place

        org    scan
step    equ    24
gap     equ    6
first   equ    loop+step*5

ptr     dat    first+gap-1     ,  first-1

        dat    0     ,  0

x       dat    1     ,  9
clr     spl    #350  ,  12
        mov    *x    ,  >ptr
        mov    *x    ,  >ptr
        djn.f  clr+1 ,  }clr

        for    2
        dat    0     ,  0
        rof

loop    add    inc   ,  ptr
scan    sne    *ptr  ,  @ptr
        djn.f  loop  ,  *ptr
        djn.f  clr   ,  ptr
inc     dat    step  ,  step
        end