Rust Sega Emulator

Conversion of a C emulator, that I'd converted to C++, that I'd converted to Python, that I've converted to Rust.

Original implementation was based on sega master system technical information from:

    SEGA MASTER SYSTEM TECHNICAL INFORMATION, by Richard Talbot-Watkins, 10th June 1998

    Z80 Instructions
    https://www.zilog.com/docs/z80/um0080.pdf

Building/Running Install Rust: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

    linux (rust toolchain dependencies):
      apt-get install build-essential

Install SDL:
    linux (debian based): 
            apt-get install libsdl2-dev
    rasbian (64-bit): 
            apt-get install libsdl2-dev
    rasberry pi (ubuntu mate 64-bit): 
            # Release 22.04 LTS (Jammy Jellyfish) 64-bit
            # Need to upgrade so 'sdl2' will install.
            apt-get update
            apt-get upgrade
            apt-get install git curl libsdl2-dev

            # 'pipewire' appears to be a good sound driver on the raspberry pi
            # SDL_AUDIODRIVER=pipewire 
    OSX: 
            brew install sdl2

Windows Build (from linux):
            sudo apt-get install gcc-mingw-w64
            rustup target add x86_64-pc-windows-gnu
            cargo build --target x86_64-pc-windows-gnu --release

            # For 'sdl' (eg: if getting 'cannot find -lSDL2: No such file or directory')
            sudo apt-get install libsdl2-dev -y
            curl -s https://www.libsdl.org/release/SDL2-devel-2.0.22-mingw.tar.gz | tar xvz -C /tmp
            cp -r /tmp/SDL2-2.0.22/x86_64-w64-mingw32/lib/* ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/

            # For raspberry pi.  Or generally, set destination directory to: $(rustup show active-toolchain | sed 's/ .*//')
            cp -r /tmp/SDL2-2.0.22/x86_64-w64-mingw32/lib/* ~/.rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/

    Webassembly
            From: https://puddleofcode.com/story/definitive-guide-to-rust-sdl2-and-emscriptem
            Then: https://users.rust-lang.org/t/sdl2-emscripten-asmjs-and-invalid-renderer-panic/66567
            Taken from: https://github.com/therocode/rust_emscripten_main_loop

            sudo apt-get install emscripten
            rustup target add wasm32-unknown-emscripten

            # Your experience may vary, adding explicit handling of 'EM_CONFIG'

            EM_CONFIG=$HOME/.emscripten emcc --generate-config
              Note: May have to manuall update/adjust available system versions in the '.emscripten' config file

            EM_CONFIG=~/.emscripten cargo build-emscripten
              Note: It's just an alias for 'cargo build --release --config projects/emscripten/'

            # Start a web server and load in browser (point it to the location reported by the python server)
            python3 -m http.server

            # Drag a rom into the 'rom drop' location in the browser.

            # Note, the configuration file in 'projects/emscripten' are the same as running:
            export EMCC_CFLAGS="-s USE_SDL=2"
            cargo build --target wasm32-unknown-emscripten



            # To try different 'emscripten' sdk versions
            git clone https://github.com/emscripten-core/emsdk.git 
            cd rustsega
            cd ../emsdk
            VER=3.1.23 && emsdk install $VER && emsdk activate $VER && . emsdk_env.sh && cd - && rm -r target && cargo build --release --config projects/emscripten/.cargo/config.toml; python -m http.server && cd -


Build and run:
    cargo run --release <rom_file>

Usage: rustsega <cartridge_name> [-d] [-n] [-s <stop-clock>] [-f] [-l]

Rusty Sega Emulator.

Positional Arguments:
  cartridge_name    name of cartridge to run

Options:
  -d, --debug       print PC State Debug Info
  -n, --no-delay    run the emulator with no delay (rather than real-time)
  -s, --stop-clock  number of clock cycles to stop the emulator (for
                    benchmarking)
  -f, --fullscreen  run the emulator in full screen mode.
  -l, --list-drivers
                    list SDL drivers
  --help            display usage information

(Current) Inputs: Key mappings (Joystick 1): Up: Up, Down: Down, Left: Left, Right: Right Fire A: Z, Fire B: X Reset: R

Quit: Escape

Note: Currently 'Quit' doesn't appear to work on Rasbian if audio output is set to HMI, when headphones are connected to the AV Jack (it just hangs).

Dependencies: Argument parsing dependency added via: cargo add clap --features derive

TODO:

Non-functional: Improve structure (current structure is shortest path to get things running). Fix status flag calculations, cross check with good known Z80 results.

Clean up 'sega.rs' there's a bit too much 'glue' going on there, that should be shifted out to the submodules.

Update vdp/cycle comparisons so they support clock rollover (currently just set cycles to 64-bit, but I doubt that's how the master system did it).

Optimise:

• Don't do full VDP processing per byte update (check for changes, isolate).
• Look for CPU cycles
• Profile

Add more tests

• Capture Timing, put in fairly full set of op code checks, so op codes can be tidied up (there's currently a lot of repetition).

Sound

• Set a better/dynamic audio queue length (based on speed/current buffer size, for better sound.)
• Fix noise/periodic channel. When 'periodic' mode is enabled, it sounds worse. Unsure what 'correct' sounds like (but superficially seems like it should have more noise, rather than high pitch pings). The 'noise' sounds reasonable, but not sure how accurate it is (currently have a frequency multiplier that probably isn't correct).

Constants

• Make SMS Height/Width available to remove magic numbers

Rust General

• cargo clippy

• profiling cargo install flamegraph

  cargo flamegraph
  #
  # Raspberry pi (ubuntu mate):
  # sudo apt-get install linux-tools-raspi
  #
  

• remove all warnigns

vim setup Currently not really sure what the best way to setup vim is. Generally, I like a 'minimal' setup, so I can easily get a consistent setup if plugins can't be used.

 It seems as though syntax highlighting works out of the box with Vim 8.1, and '!cargo fmt' seems to work well.

 my ~/.vimrc, (with rust additions):
    silent !stty -ixon

    " format for rust errors
    set efm=%.%#-->\ %f:%l:%c
    " format for git searches
    set efm+=%f:%l:%m
    
    au FileType rust set makeprg=cargo

    nnoremap <C-s> :cgetexpr system('git grep --recurse-submodules -n '. expand('<cword>'))<CR>

Note to self, try these: git clone --depth 1 https://github.com/preservim/nerdtree.git ~/.vim/pack/vendor/start/nerdtree git clone --depth 1 https://github.com/dense-analysis/ale.git ~/.vim/pack/git-plugins/start/ale git clone --depth 1 https://github.com/timonv/vim-cargo ~/.vim/pack/git-plugins/start/vim-cargo

Compilation errors:

SDL2:

  = note: /usr/bin/ld: cannot find -lSDL2
          collect2: error: ld returned 1 exit status
          
error: could not compile `rustsega` due to previous error

Fix: Install SDL2:

perf setup (for flamegraph, see https://docs.kernel.org/admin-guide/perf-security.html): which perf

as root/sudo:

cd /usr/bin ls -l perf chgrp perf_users perf chmod o-rwx perf setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf getcap perf usermod -a -G perf_users