Four Lines of Redcode

The Sierpinski triangle or gasket is a fractal named after the Polish mathematician Waclaw Sierpinski. Surprisingly the fractal can be generated with just 4 lines of Redcode:

        width  equ 126
        trail  equ (sum-CORESIZE%width)
        start  equ (trail-width+1)

sum     mov    #3,    @3
ptr     mov.b  trail, sum
        add.b  {ptr,  sum
        djn    sum,   #start

The magic incantation for pMARS is pmars -v 132. Alternatively set the width to 128 to view using CoreWin :-)

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 )