Intel x86 ASM Codegolf

Write an Intel x86 assembly program that -- when compiled with the provided Makefile -- returns an ASCII compass.

The goal is to minimize the binary size.

Expected output

The template for the output is provided in compass.txt. The program is passed a digit (ASCII) between 0 and 7. The numbers stand for directions:

• 0: North
• 1: Northeast
• 2: East
• 3: Southeast
• 4: South
• 5: Southwest
• 6: West
• 7: Northwest

The expected output for all those directions can be found in expected.txt.

Example:

$ ./main 3
   _N_
  /   \
W|  .  |E
 |   \ |
  \_ _/
    S

Constraints

• The code needs to be written in 32 bit Intel (x86) assembly (NASM syntax).
• No library calls are allowed, use syscalls instead

Hall of Fame

Sorted by binary size (in bytes).

We used to have a website with an auto-verifier, but it's been offline for a few years now. If you have a working solution, send the assembly file and your nickname to [email protected] and I'll add you to the highscore list!

• ken & tbrunner: 292 bytes (2015-04-20)
• tbrunner: 328 (2015-04-20)
• schmijos & rnestler: 336 (2014-10-11)
• schmijos: 372 (2014-08-11)
• rnestler: 396 (2014-09-29)
• Danilo: 436 (2014-10-09)
• Danilo & Chrigi: 452 (2014-07-25)
• Stéphane: 536 (2016-08-17)
• maccesch: 644 (2015-07-27)
• Matthias: 712 (2016-08-10)
• rruettimann: 732 (2015-08-17)
• macav: 752 (2016-02-22)
• tobias: 768 (2016-02-02)
• shuber: 820 (2015-07-10)
• chuvisco88: 820 (2016-09-22)
• Ali @renuo: 824 (2015-06-24)

Verification

Build the binary using Make.

$ make
nasm -f elf32 -O0 main.s
ld -m elf_i386 -s -O0 -o main main.o

Run the test script with Python 3:

$ python3 test.py
Success!
Binary size is 460 bytes.

Debugging

If you want a binary with debug symbols included, use the debug Make target:

$ make debug
nasm -f elf32 -g -O0 main.s
ld -m elf_i386 -O0 -o debug main.o
$ gdb ./debug
(gdb) ...

Docker

You can also verify the code within an isolated Docker instance.

$ docker build -t codegolf .
...
$ export SRC=/path/to/source/dir
$ export FILE=filename.s
$ docker run --rm \
  -v $SRC:/code \
  -u compass -w /home/compass/codegolf \
  codegolf \
  /bin/bash -c "cp /code/$FILE main.s && make && python test.py"