Redcode Talk Issue 1

Christian Schmidt recently published the first issue of Redcode Talk. The issue contains a couple of articles by Fizmo:

• The undiscovered area between LP & 94draft
  
• Random Warrior Talk: One Man Army v1.0
  

Happy Numbers

Today's Programming Praxis challenges us to write a program to list the happy numbers up to a given limit. A number is happy if the sum of the square of it's digital eventually reaches 1. E.g. 7 is happy because 7²=49, 4²+9²=97, 9²+7²=130, 1²+3²+0²=10, 1²+0²=1.

Here's my solution in Redcode:

org    newcand

        base   equ 10
        limit  equ 100
        tries  equ 50

stack   dat    0
happy   dat    1
cand    dat    0
total   dat    0
repeat  dat    0
 
newcand mov.ba happy,     cand
        mov    #tries,    repeat
again   mov    #-1,       total
digits  mov.ab cand,      cand
        mod    #base,     cand
        div.a  #base,     cand
        mul.b  cand,      cand
        add.b  cand,      total
        jmn.a  digits,    cand
        jmz    found,     total
        mov.ba total,     cand
        add.a  #1,        cand
        djn    again,     repeat
nexthap seq    #limit,    happy
        jmp    newcand,   >happy
        dat    0

found   mov.b  happy,     <stack
writen  mov.b  @stack,    <stack
        div    #10,       >stack
        mod    #10,       @stack
        add    #48,       @stack
        jmn    writen,    <stack
        add    #1,        stack
wloop   sts    >stack,    0
        jmn    wloop,     stack
        sts.a  #10,       0
        jmp    nexthap

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?