Brainfuck compiler with x86 and C backends written in Racket

Written mostly as an exercise to understand x86 NASM Linux assembly, can generate NASM code and assemble it into an ELF executable or generate C code.

Currently both targets support 30,000 8-bit cells with wrapping values (255 + 1 = 0, 0 - 1 = 255).

Output is always finished with \n\r (so if a program produces no \n, it will be added, and if it does - no additional line feed will be printed).

Generated ELF executable is still dependant on glibc (mostly for system call to stty).

Cool examples

bfc examples/hanoi.bf # draws Hanoi towers
bfc examples/architecture.bf # examine size of bf cells

Dependencies

• x86 target works on 32- and 64-bit Intel machines running Linux
• C target can be compiled and run on basically any system

• racket, raco
• nasm
• gcc-multilib (needed to link 32-bit object files on 64-bit machines)

Basically after generating NASM assemly, bfc calls nasm -f elf FILE.asm and gcc -m32 FLIE.o, so if these commands work, everything shoud work correctly).

Usage

You can run bfc.rkt through racket or you can compile it (compilation will probably not make it faster). make to compile.

./bfc -h for command line options

Generate executable ./hw

bfc -o ./hw examples/hello_world.bf

Generate only hanoi.asm (NASM assembly)

bfc -S examples/hanoi.bf

Target C code

bfc --target C examples/99_bottles.bf

Known bugs and workarounds

For non-English keyboar layouts (e.g. Polish) and zsh

After you run a compiled bf program (either target x86 or compiled output of C target) using zsh shell, funny things happen when you try to enter some special characters, like e.g. ł. reset helps, stty sane doesn't do anything.

This probably stems from incorrect usage of stty.

bash doesn't seem to be affected.

Uncomfortable command line options

bfc uses Racket's command-line which means that flags must come before name of the compiled file, so

bfc -o hw hello_world.bf

is correct, but not

bfc hello_world.bf -o hw

TODO

• WebAssembly target
• infinite cell array switch and customizable cell array length
• customizable cell size (8-, 16- and 32-bit)
• play with optimizations, e.g. changing [-] to mov byte[ecx], 0, currently only trivial ones are implemented (like -++-++++ becomes add byte[ecx], 4)
• specifying output by dir, like bfc -o ../ a.bf