mario++

About

This is an almost-100% mechanical conversion of Super Mario Bros.'s 6502 instructions to C++ operations, along with some emulation glue, so we can display it and receive controller presses.

It's clearly not perfect; obvious PPU emulation bugs exist:

mario++.clip1.mp4

But it's a start toward having something working that will be refactored. My plan is to gradually migrate the "raw" 6502 operations into pure C++ logic, including structures, classes, and so on. Ultimately I want to have a play area larger than 256 pixels wide; to have enemies and other objects and their behaviors encapsulated into proper classes; and so on.

Each conversion step will be a documented PR doing such encapsulation, with the project being "completed" when there are no remaining (or, at least, no more interesting) original 6502 instructions, and when I hit the targets set for myself (wider screen, left-scroll, new enemies, new levels). Or until I get tired of this. :)

I thought it would be fun to see what happens when you go to the "minus world" at the end of 1-2. Perhaps someday when this is refactored and data are better organized into proper structs and so on, this would trigger an ASAN or MSAN error, i.e., detect the condition when an errant read occurs like the game does when trying to access the "blank" world (which is actually "world 36").

mario++.minusworld.mp4

Requirements

• LLVM w/ Clang; a new enough version supporting -std=c++23
• sfml graphics library: on OSX, run brew install sfml
• and finally make.

Getting started

Make sure you have a new-ish LLVM/Clang and SFML, and just run make.

TODOs

Emulation TODOs

• refactor emu classes, they're a mess
• some known bugs in PPU emulation: sprite priority and scrolling

C++-generator TODOs

• have functions contain code blocks with their own labels, and not "branching" to another function altogether (just goto that label)
• identify memory (RAM locations in 0x0000-0x07ff, ROM within 0x8000-0xffff) which are used by only one function, and make them static within those functions (as opposed to the giant G structure in main.h/.cc)

Thanks

Thanks to doppelganger who reverse engineered and commented the entire assembly listing of the game. https://gist.github.com/1wErt3r/4048722

Also thanks to bombela for backward.hpp, which has been invaluable in debugging efforts. https://github.com/bombela/backward-cpp