# minix-8086-rs

minix-8086-rs is a Rust-based toolchain for analyzing and interpreting 16-bit 8086 binaries, made with the intention of interpreting binaries compiled for MINIX.

It includes:
- 📦 a.out Parser: Parses legacy MINIX executables.
- 🛠 8086 Disassembler: Parses 16-bit instructions into an IR and prints them in a `objdump(1)`-style fashion.
- 💻 8086 Interpreter: Interprets the 8086 instructions, i.e., the MINIX binary.

## Usage

To compile and run the tool, use Cargo:
```
cargo build --release
```

Or run it directly:
```
cargo run -- --help
```

Run with debug output:
```
RUST_LOG=debug cargo run -- interpret -p ./a.out
```

CLI Options:
```
$ cargo run -- --help
Simple program to disassemble and interpret 8086 a.out compilates, e.g. such for MINIX 
                                                                                       
Usage: minix-8086-rs [OPTIONS] <COMMAND>                                               
                                                                                       
Commands:                                                                              
  disasm     Disassemble the binary into 8086 instructions                             
  interpret  Interpret the 8086 instructions                                           
  help       Print this message or the help of the given subcommand(s)                 
                                                                                       
Options:                                                                               
  -p, --path <PATH>  Path of the binary                                                
  -h, --help         Print help                                                        
  -V, --version      Print version                                                     
```

## Status

This project is under active development and primarily used by me to explore some Intel disassembly and learn some more Rust.
Expect bugs and some missing features.
I mainly test with 'official' binaries from the MINIX source tree.


## Documentation

The documentation of the project itself can be accessed by using `cargo doc`.
```
$ cargo doc
$ firefox target/doc/minix_8086_rs/index.html 
```

For the implementation of all instructions I used the Intel "8086 16-BIT HMOS MICROPROCESSOR" Spec, as well as [this](http://www.mlsite.net/8086/8086_table.txt) overview of all Opcode variants used in conjunction with [this](http://www.mlsite.net/8086/) decoding matrix.


## FAQ

#### Why hassle with interpretation and not just emulate 8086?
For once, this project stemmed from a university exercise about the 8086 instruction set and disassembly.
An interpreter was the logical (?) next step.
Maybe I add 8086 emulation some day.

#### Why no `nom`?
There is no real reason, I just wanted to try to implement most parts myself, even if it meant more boilerplate code.
I used `nom` extensivly in the past and I just wanted to see what it would be like without that crate.
In hindsight, using `nom` would have been the cleaner option, but hey, something I only learned by not using `nom` for once.