bfc

Brainfuck is an minimal and esoteric language.

For example, the following is a Hello World program. See the link above for more details on how it works, it's actually quite simple.

++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.

This package implements a simple compiler for Brainfuck. The compiler generates Intel x86 Assembly, uses nasm to assemble and then ld to link the result into a x86 ELF executable.

Dependencies

nasm assembler
ld - usually already installed
The Rust Toolchain

Other than the above, no other dependencies are used.

Usage

Compiler

# Compiles examples/hello_world.bf, writes the binary to `hello_world` in the 
# same directory.
$ cargo run --release --quiet examples/hello_world.bf hello_world

$ ./hello_world
Hello World!

Interpreter

An intepreter is also included:

$ cargo run --release --quiet --bin vm examples/hello_world.bf
Hello World!

Testing

The examples/ directory contains example programs (not written by me) and the expected stdout after execution. This can also be tested programmatically with the following command.

$ cargo test

Benchmarks

Here is a comparison between the interpreter and the compiled executable for mandelbrot.bf.

$ hyperfine 'cargo run --release --quiet --bin vm examples/mandelbrot.bf' 'cargo run --release --quiet examples/mandelbrot.bf target/mandelbrot && target/mandelbrot'
Benchmark 1: cargo run --release --quiet --bin vm examples/mandelbrot.bf
  Time (mean ± σ):      4.894 s ±  0.022 s    [User: 4.889 s, System: 0.005 s]
  Range (min … max):    4.878 s …  4.950 s    10 runs
 
Benchmark 2: cargo run --release --quiet examples/mandelbrot.bf target/mandelbrot && target/mandelbrot
  Time (mean ± σ):     776.3 ms ±   7.0 ms    [User: 770.5 ms, System: 5.9 ms]
  Range (min … max):   771.4 ms … 792.9 ms    10 runs
 
Summary
  'cargo run --release --quiet examples/mandelbrot.bf target/mandelbrot && target/mandelbrot' ran
    6.30 ± 0.06 times faster than 'cargo run --release --quiet --bin vm examples/mandelbrot.bf'

Seems pretty decent, though I didn't put in much effort in optimizations beyond creating a jump table for jump instructions and compressing consecutive instructions. See parser.rs for details.

Resources

This was mainly an adventure in learning about compilers and assembly since I have no experience in systems programming. I was inspired by the following:

Adventures in JIT compilation

jiahaog / bfc

bfc