rustboyadvance-ng/README.md

# RustBoyAdvance-NG

[![Build Status](https://travis-ci.com/michelhe/rustboyadvance-ng.svg?branch=master)](https://travis-ci.com/michelhe/rustboyadvance-ng)

RustBoyAdvance-NG aims to be a Nintendo GameBoy Advance emulator and debugger, written in the rust programming language.

RustBoyAdvance-NG currently has implemented
  - Dumbed-down ARM/THUMB mode disassembling
  - Some ARM/THUMB instruction are implemented, but not all of them.
  - A neat debugger REPL

But the way for full emulation is way far ahead, because most of the ARM/THUMB instructions are not yet implemented.

# Using the REPL

You need to have rust installed, and somehow legally obtain a gba bios binary.
Currently to test the debugger, any binary file containing arm mode instructions will do.

```bash
$ cargo run -- debug
```

![Debugger REPL Demo](img/demo.gif)

# Why is this project needed ?

It's actually **not**. There are quite a lot of GBA emulators, ~~and even some written in rust~~. Actually, I couldn't find any game capable emulators written in rust.

I'm only doing this as a side project intended for learning rust.

This is my *third* take on this project. My first go at this was about 3 years ago, but I didn't like rust much at the time so it got abandoned.
I tried to resurrect it a year ago but didn't have the time to get invested in a side-project, let alone learning rust.

I've grown to like rust a lot since then, so here we go again.
You know what they say, *third time's a charm*.

# Links

- [ARM7TDMI Technical Reference Manual](http://infocenter.arm.com/help/topic/com.arm.doc.ddi0210c/DDI0210B.pdf)
    Technical Reference Manuals are **fun**.
- [GBATEK](http://problemkaputt.de/gbatek.htm)
    A single webpage written by *no$gba* developer  Martin Korth.
    This page has pretty much everything. Seriously, it's the best.
- [NanoboyAdvance](https://github.com/fleroviux/NanoboyAdvance)]
    A GameBoy Advance emulator written in C++17 by a nice person called fleroviux.
    I've used this emulator to search for a tough bug in mine.
Update README.md 2019-06-28 11:05:48 +01:00			`# RustBoyAdvance-NG`

			`[![Build Status](https://travis-ci.com/michelhe/rustboyadvance-ng.svg?branch=master)](https://travis-ci.com/michelhe/rustboyadvance-ng)`

			`RustBoyAdvance-NG aims to be a Nintendo GameBoy Advance emulator and debugger, written in the rust programming language.`

			`RustBoyAdvance-NG currently has implemented`
Update README.md Former-commit-id: 03b224b7de9735a1ed43dd7460fe5fa9ece147b4 2019-07-03 00:23:36 +01:00			`- Dumbed-down ARM/THUMB mode disassembling`
			`- Some ARM/THUMB instruction are implemented, but not all of them.`
Update README.md 2019-06-28 11:05:48 +01:00			`- A neat debugger REPL`

			`But the way for full emulation is way far ahead, because most of the ARM/THUMB instructions are not yet implemented.`

			`# Using the REPL`

			`You need to have rust installed, and somehow legally obtain a gba bios binary.`
			`Currently to test the debugger, any binary file containing arm mode instructions will do.`

			```bash
			`$ cargo run -- debug`
			```

Add demo gif to README.md Former-commit-id: 05ec55725c04cd4d4ca08471ea88b1b6b1b11e08 2019-06-28 13:32:21 +01:00			`![Debugger REPL Demo](img/demo.gif)`
Update README.md 2019-06-28 11:05:48 +01:00
			`# Why is this project needed ?`

Update README.md Former-commit-id: 03b224b7de9735a1ed43dd7460fe5fa9ece147b4 2019-07-03 00:23:36 +01:00			`It's actually not. There are quite a lot of GBA emulators, ~~and even some written in rust~~. Actually, I couldn't find any game capable emulators written in rust.`
Update README.md 2019-06-28 11:05:48 +01:00
			`I'm only doing this as a side project intended for learning rust.`

			`This is my third take on this project. My first go at this was about 3 years ago, but I didn't like rust much at the time so it got abandoned.`
			`I tried to resurrect it a year ago but didn't have the time to get invested in a side-project, let alone learning rust.`

			`I've grown to like rust a lot since then, so here we go again.`
			`You know what they say, third time's a charm.`

			`# Links`

			`- [ARM7TDMI Technical Reference Manual](http://infocenter.arm.com/help/topic/com.arm.doc.ddi0210c/DDI0210B.pdf)`
			`Technical Reference Manuals are fun.`
			`- [GBATEK](http://problemkaputt.de/gbatek.htm)`
			`A single webpage written by no$gba developer Martin Korth.`
Update README.md Former-commit-id: 03b224b7de9735a1ed43dd7460fe5fa9ece147b4 2019-07-03 00:23:36 +01:00			`This page has pretty much everything. Seriously, it's the best.`
Fix that DAMN bug. Long story short, I've been hunting this bug for a while now. While passing armwresteler tests, I still had an emulation bug which causeed libgcc's iprintf to produce bugged strings. In order to find it, I've used https://github.com/fleroviux/NanoboyAdvance/ And patched it to produce a formatted log of every step of the execution of iprintf: {OPCODE} {PC} {R0} {R1} ... {R14} {FLAGS} Did the same on my emulator and searched for differences. Found out the a "CMP r3, #0x0" instruction turned off the carry flag when it shouldn't. Found this sad function, the check I'm using for carry flag is meaningless when done on signed integers. :sigh: Former-commit-id: 871d2581921796dae9bf4f5fdaa45c6ad46aebec 2019-11-05 22:40:06 +00:00			`- [NanoboyAdvance](https://github.com/fleroviux/NanoboyAdvance)]`
			`A GameBoy Advance emulator written in C++17 by a nice person called fleroviux.`
			`I've used this emulator to search for a tough bug in mine.`