Cross Simulator Core Graphics

One difficulty when trying to write code to plot graphics in Redcode is the width of the core display. The four most popular simulators uses a variety of different widths:

Simulator	Display Width
pMARS SDL mode 0	157
pMARS SDL mode 2	126
CoreWin	128
ARES	80
nMars	various

The simplest solution is to define a variable for the width which can be modified by the person running the program. Alternatively it's possible to use the the predefined VERSION constant to determine the simulator:

Simulator	Version
pMARS SDL mode 0	92
pMARS SDL mode 2	92
CoreWin	230
ARES	0
nMars	93

Putting the two together we can write the following code which sets the correct width for pMARS SDL, CoreWin and ARES:

width equ ( (VERSION==92)*157 + (VERSION==230)*128 + (VERSION==0)*80 )

Fractals in Corewar

In 1997 Anton Marsden organised a Corewar tournament with a difference.  The three rounds challenged players to use Redcode to solve a variety of problems.

In the third round of Anton's Corewar Tournament the challenge was to write a Redcode program to draw a pretty picture.  First place was taken by Ilmari Karonen with a fractal fern.

Here's my own attempt at creating a pretty picture in the core view of pMARS. It's a fractal known as the Koch Curve.

Here's the program, just 18 instructions:

width equ 157

        org    koch

        stack equ count+30

koch:   mov    #2-ptr, >stack
        jmp    count,  }move

        sub.a  #2,     move
        mov    #2-ptr, >stack
        jmp    count

        jmp    return, }move

count:  djn    koch,   #11
        mod.a  #8,     move
        div.a  #2,     move
        add.b  *move,  pos
        mul.a  #2,     move
pos:    add    #1,     koch+71*width/2+16
return: mov.ba <stack, ptr
ptr:    jmp    0,      >count

move:   dat    -1
        dat    -width
        dat    1
        dat    width

Have you tried to write a graphical display in Corewar?