chore: Release lemur version 0.3.2

Reviewed-on: #3

.gitattributes

@@ -4,6 +4,7 @@
 *.html  text eol=lf diff=html
 *.java  text eol=lf diff=java
 *.js    text eol=lf diff=js
+*.sh    text eol=lf
 *.txt   text eol=lf
 
 *.class binary

.gitignore

@@ -1,4 +1,5 @@
-/shrooms-vb
-/shrooms-vb.exe
-.vscode
-output
+/lemur
+/lemur.exe
+.vscode
+output
+/target

Cargo.toml

@@ -0,0 +1,58 @@
+[package]
+name = "lemur"
+description = "An emulator for the Virtual Boy."
+repository = "https://git.virtual-boy.com/PVB/lemur"
+publish = false
+license = "MIT"
+version = "0.3.2"
+edition = "2021"
+
+[dependencies]
+anyhow = "1"
+atoi = "2"
+atomic = "0.6"
+bitflags = { version = "2", features = ["serde"] }
+bytemuck = { version = "1", features = ["derive"] }
+clap = { version = "4", features = ["derive"] }
+cpal = { git = "https://github.com/sidit77/cpal.git", rev = "66ed6be" }
+directories = "5"
+egui = { version = "0.30", features = ["serde"] }
+egui_extras = { version = "0.30", features = ["image"] }
+egui-toast = { git = "https://github.com/urholaukkarinen/egui-toast.git", rev = "d0bcf97" }
+egui-winit = "0.30"
+egui-wgpu = { version = "0.30", features = ["winit"] }
+gilrs = { version = "0.11", features = ["serde-serialize"] }
+hex = "0.4"
+image = { version = "0.25", default-features = false, features = ["png"] }
+itertools = "0.13"
+num-derive = "0.4"
+num-traits = "0.2"
+oneshot = "0.1"
+pollster = "0.4"
+rfd = "0.15"
+rtrb = "0.3"
+rubato = "0.16"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+thread-priority = "1"
+tokio = { version = "1", features = ["io-util", "macros", "net", "rt", "sync"] }
+tracing = { version = "0.1", features = ["release_max_level_info"] }
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+wgpu = "23"
+winit = { version = "0.30", features = ["serde"] }
+
+[target.'cfg(windows)'.dependencies]
+windows = { version = "0.58", features = ["Win32_System_Threading"] }
+
+[build-dependencies]
+cc = "1"
+winresource = "0.1"
+
+[profile.release]
+lto = true
+
+[package.metadata.bundle]
+name = "Lemur"
+identifier = "com.virtual-boy.Lemur"
+icon = ["assets/lemur-256x256.png"]
+category = "games"

README.md

@@ -1,15 +1,25 @@
-# Shrooms VB (native)
+# Lemur
 
-An SDL-based implementation of shrooms-vb.
+A Virtual Boy emulator built around the shrooms-vb core. Written in Rust, using winit, wgpu, and egui. Should run on any major OS.
 
 ## Setup
 
 Install the following dependencies:
- - `gcc` (or MinGW on Windows) (or whatever, just set `CC`)
- - `pkg-config`
- - sdl2
+ - `cargo` (via [rustup](https://rustup.rs/), the version from your package manager is too old)
 
 Run
 ```sh
-make build
-```
+cargo build --release
+```
+
+The executable will be in `target/release/lemur[.exe]`
+
+## Release
+
+Bump the version number in `Cargo.toml`, then run this script:
+
+```sh
+./scripts/release.sh
+```
+
+It uses docker to cross compile for Windows, MacOS, and Linux. All binaries are left in the `output` directory.

assets.h

@@ -1,12 +0,0 @@
-#ifndef SHROOMS_VB_NATIVE_ASSETS_
-#define SHROOMS_VB_NATIVE_ASSETS_
-
-#include <stdint.h>
-
-extern const uint8_t _binary_assets_lefteye_bin_start;
-const uint8_t *LEFT_EYE_DEFAULT = &_binary_assets_lefteye_bin_start; 
-
-extern const uint8_t _binary_assets_righteye_bin_start;
-const uint8_t *RIGHT_EYE_DEFAULT = &_binary_assets_righteye_bin_start; 
-
-#endif

audio.c

@@ -1,65 +0,0 @@
-#include <audio.h>
-#include <stdio.h>
-
-void audioCallback(void *userdata, uint8_t *stream, int len) {
-    AudioContext *aud;
-    SDL_assert(len == 834 * 4);
-
-    aud = userdata;
-    if (!aud->filled) {
-        /* too little data, play silence */
-        SDL_memset4(stream, 0, 834);
-        return;
-    }
-    SDL_memcpy4(stream, aud->buffers[aud->current], 834);
-    ++aud->current;
-    aud->current %= 2;
-    aud->filled -= 1;
-} 
-
-int audioInit(AudioContext *aud) {
-    SDL_AudioSpec spec;
-    spec.freq = 41700;
-    spec.format = AUDIO_S16;
-    spec.channels = 2;
-    spec.samples = 834;
-    spec.callback = &audioCallback;
-    spec.userdata = aud;
-
-    aud->id = SDL_OpenAudioDevice(NULL, 0, &spec, NULL, 0);
-    aud->paused = true;
-    if (!aud->id) {
-        fprintf(stderr, "could not open audio device: %s\n", SDL_GetError());
-        return -1;
-    }
-    aud->current = 0;
-    aud->filled = 0;
-    return 0;
-}
-
-int audioUpdate(AudioContext *aud, void *data, uint32_t bytes) {
-    int filled;
-    if (!aud->id) return -1;
-    SDL_assert(bytes == 834 * 4);
-
-    SDL_LockAudioDevice(aud->id);
-    if (aud->filled < 2) {
-        int next = (aud->current + aud->filled) % 2;
-        SDL_memcpy4(aud->buffers[next], data, bytes / 4);
-        aud->filled += 1;
-    }
-    filled = aud->filled;
-    SDL_UnlockAudioDevice(aud->id);
-
-    if (aud->paused) {
-        SDL_PauseAudioDevice(aud->id, false);
-        aud->paused = false;
-    }
-
-    while (filled > 1) {
-        SDL_Delay(0);
-        filled = aud->filled;
-    }
-
-    return 0;
-}

audio.h

@@ -1,18 +0,0 @@
-#ifndef SHROOMS_VB_NATIVE_AUDIO_
-#define SHROOMS_VB_NATIVE_AUDIO_
-
-#include <SDL2/SDL.h>
-#include <stdbool.h>
-
-typedef struct {
-    SDL_AudioDeviceID id;
-    bool paused;
-    uint32_t buffers[2][834];
-    int current;
-    int filled;
-} AudioContext;
-
-int audioInit(AudioContext *aud);
-int audioUpdate(AudioContext *aud, void *data, uint32_t bytes);
-
-#endif

build.Dockerfile

@@ -0,0 +1,37 @@
+# This Dockerfile produces a base image for builds.
+# It includes all dependencies necessary to cross-compile for Windows/MacOS/Linux.
+
+FROM crazymax/osxcross:latest-ubuntu AS osxcross
+
+FROM rust:latest
+RUN rustup target add x86_64-pc-windows-msvc && \
+    rustup target add x86_64-apple-darwin && \
+    rustup target add aarch64-apple-darwin && \
+    apt-get update && \
+    apt-get install -y clang-19 lld-19 libc6-dev libasound2-dev libudev-dev genisoimage mingw-w64 && \
+    cargo install cargo-bundle xwin && \
+    xwin --accept-license splat --output xwin && \
+    rm -rf .xwin-cache && \
+    ln -s $(which clang-19) /usr/bin/clang && \
+    ln -s $(which clang++-19) /usr/bin/clang++
+COPY --from=osxcross /osxcross /osxcross
+
+ENV PATH="/osxcross/bin:$PATH" \
+    LD_LIBRARY_PATH="/osxcross/lib" \
+    CC="clang-19" CXX="clang++-19" AR="llvm-ar-19" \
+    CC_x86_64-apple-darwin="o64-clang" \
+    CXX_x86_64-apple-darwin="o64-clang++" \
+    CC_aarch64-apple-darwin="oa64-clang" \
+    CXX_aarch64-apple-darwin="o6a4-clang++" \
+    SHROOMS_CFLAGS_x86_64-unknown-linux-gnu="-flto" \
+    CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS="-Clinker-plugin-lto -Clinker=clang -Clink-arg=-fuse-ld=lld" \
+    SHROOMS_CFLAGS_x86_64-pc-windows-msvc="-flto" \
+    CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_RUSTFLAGS="-Lnative=/xwin/crt/lib/x86_64 -Lnative=/xwin/sdk/lib/um/x86_64 -Lnative=/xwin/sdk/lib/ucrt/x86_64 -Clinker-plugin-lto -Clink-arg=-fuse-ld=lld" \
+    CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_LINKER="lld-link-19" \
+    CARGO_TARGET_X86_64_APPLE_DARWIN_LINKER="o64-clang" \
+    CARGO_TARGET_X86_64_APPLE_DARWIN_AR="llvm-ar-19" \
+    CARGO_TARGET_AARCH64_APPLE_DARWIN_LINKER="oa64-clang" \
+    CARGO_TARGET_AARCH64_APPLE_DARWIN_AR="llvm-ar-19" \
+    CROSS_COMPILE="setting-this-to-silence-a-warning-" \
+    RC_PATH="llvm-rc-19" \
+    MACOSX_DEPLOYMENT_TARGET="14.5"

build.rs

@@ -0,0 +1,34 @@
+use std::{error::Error, path::Path};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    if std::env::var("CARGO_CFG_TARGET_OS")? == "windows" {
+        let mut res = winresource::WindowsResource::new();
+        res.set_icon("assets/lemur.ico");
+        res.compile()?;
+    }
+
+    println!("cargo::rerun-if-changed=shrooms-vb-core");
+
+    let mut builder = cc::Build::new();
+    let _ = builder.try_flags_from_environment("SHROOMS_CFLAGS");
+    let opt_level = if builder.get_compiler().is_like_msvc() {
+        2
+    } else {
+        3
+    };
+    builder
+        .include(Path::new("shrooms-vb-core/core"))
+        .opt_level(opt_level)
+        .flag_if_supported("-fno-strict-aliasing")
+        .define("VB_LITTLE_ENDIAN", None)
+        .define("VB_SIGNED_PROPAGATE", None)
+        .define("VB_DIV_GENERIC", None)
+        .define("VB_DIRECT_EXECUTE", "on_execute")
+        .define("VB_DIRECT_FRAME", "on_frame")
+        .define("VB_DIRECT_READ", "on_read")
+        .define("VB_DIRECT_WRITE", "on_write")
+        .file(Path::new("shrooms-vb-core/core/vb.c"))
+        .compile("vb");
+
+    Ok(())
+}

cli.c

@@ -1,11 +0,0 @@
-#include <cli.h>
-#include <stdio.h>
-
-int parseCLIArgs(int argc, char **argv, CLIArgs *args) {
-    if (argc != 2) {
-        fprintf(stderr, "usage: %s /path/to/rom.vb\n", argv[0]);
-        return 1;
-    }
-    args->filename = argv[1];
-    return 0;
-}

cli.h

@@ -1,10 +0,0 @@
-#ifndef SHROOMS_VB_NATIVE_CLI_
-#define SHROOMS_VB_NATIVE_CLI_
-
-typedef struct {
-    char *filename;
-} CLIArgs;
-
-int parseCLIArgs(int argc, char **argv, CLIArgs *args);
-
-#endif

controller.c

@@ -1,65 +0,0 @@
-#include <controller.h>
-
-#define VB_PWR 0x0001
-#define VB_SGN 0x0002
-#define VB_A   0x0004
-#define VB_B   0x0008
-#define VB_RT  0x0010
-#define VB_LT  0x0020
-#define VB_RU  0x0040
-#define VB_RR  0x0080
-#define VB_LR  0x0100
-#define VB_LL  0x0200
-#define VB_LD  0x0400
-#define VB_LU  0x0800
-#define VB_STA 0x1000
-#define VB_SEL 0x2000
-#define VB_RL  0x4000
-#define VB_RD  0x8000
-
-static uint16_t symToMask(SDL_KeyCode sym) {
-    switch (sym) {
-    default: return 0;
-    case SDLK_a:
-        return VB_SEL;
-    case SDLK_s:
-        return VB_STA;
-    case SDLK_d:
-        return VB_B;
-    case SDLK_f:
-        return VB_A;
-    case SDLK_e:
-        return VB_LT;
-    case SDLK_r:
-        return VB_RT;
-    case SDLK_i:
-        return VB_RU;
-    case SDLK_j:
-        return VB_RL;
-    case SDLK_k:
-        return VB_RD;
-    case SDLK_l:
-        return VB_RR;
-    case SDLK_UP:
-        return VB_LU;
-    case SDLK_LEFT:
-        return VB_LL;
-    case SDLK_DOWN:
-        return VB_LD;
-    case SDLK_RIGHT:
-        return VB_LR;
-    }
-}
-
-void ctrlInit(ControllerState *ctrl) {
-    ctrl->keys = VB_SGN;
-}
-void ctrlKeyDown(ControllerState *ctrl, SDL_Keycode sym) {
-    ctrl->keys |= symToMask(sym);
-}
-void ctrlKeyUp(ControllerState *ctrl, SDL_Keycode sym) {
-    ctrl->keys &= ~symToMask(sym);
-}
-uint16_t ctrlKeys(ControllerState *ctrl) {
-    return ctrl->keys;
-}

controller.h

@@ -1,16 +0,0 @@
-#ifndef SHROOMS_VB_NATIVE_CONTROLLER_
-#define SHROOMS_VB_NATIVE_CONTROLLER_
-
-#include <SDL2/SDL.h>
-#include <stdint.h>
-
-typedef struct {
-    uint16_t keys;
-} ControllerState;
-
-void ctrlInit(ControllerState *ctrl);
-void ctrlKeyDown(ControllerState *ctrl, SDL_Keycode sym);
-void ctrlKeyUp(ControllerState *ctrl, SDL_Keycode sym);
-uint16_t ctrlKeys(ControllerState *ctrl);
-
-#endif

game.c

@@ -1,71 +0,0 @@
-#include <audio.h>
-#include <assets.h>
-#include <controller.h>
-#include <game.h>
-#include <SDL2/SDL.h>
-#include <stdbool.h>
-#include <time.h>
-
-typedef struct {
-    GraphicsContext *gfx;
-    AudioContext aud;
-    int16_t audioBuffer[834 * 2];
-} GameState;
-
-int onFrame(VB *sim) {
-    static uint8_t leftEye[384*224];
-    static uint8_t rightEye[384*224];
-    GameState *state;
-    void *samples;
-    uint32_t samplePairs;
-
-    state = vbGetUserData(sim);
-    
-    vbGetPixels(sim, leftEye, 1, 384, rightEye, 1, 384);
-    gfxUpdateLeftEye(state->gfx, leftEye);
-    gfxUpdateRightEye(state->gfx, rightEye);
-
-    samples = vbGetSamples(sim, NULL, &samplePairs);
-    audioUpdate(&state->aud, samples, samplePairs * 4);
-    vbSetSamples(sim, samples, 834);
-    gfxRender(state->gfx);
-    return 1;
-}
-
-#define MAX_STEP_CLOCKS 20000000
-
-int runGame(VB *sim, GraphicsContext *gfx) {
-    uint32_t clocks;
-    SDL_Event event;
-    GameState state;
-    ControllerState ctrl;
-
-    state.gfx = gfx;
-    audioInit(&state.aud);
-    vbSetSamples(sim, &state.audioBuffer, 834);
-    vbSetUserData(sim, &state);
-    vbSetFrameCallback(sim, &onFrame);
-
-    ctrlInit(&ctrl);
-
-    gfxUpdateLeftEye(gfx, LEFT_EYE_DEFAULT);
-    gfxUpdateRightEye(gfx, RIGHT_EYE_DEFAULT);
-
-    while (1) {
-        clocks = MAX_STEP_CLOCKS;
-        vbEmulate(sim, &clocks);
-
-        while (SDL_PollEvent(&event)) {
-            if (event.type == SDL_QUIT) {
-                return 0;
-            }
-            if (event.type == SDL_KEYDOWN) {
-                ctrlKeyDown(&ctrl, event.key.keysym.sym);
-            }
-            if (event.type == SDL_KEYUP) {
-                ctrlKeyUp(&ctrl, event.key.keysym.sym);
-            }
-        }
-        vbSetKeys(sim, ctrlKeys(&ctrl));
-    }
-}

game.h

@@ -1,9 +0,0 @@
-#ifndef SHROOMS_VB_NATIVE_GAME_
-#define SHROOMS_VB_NATIVE_GAME_
-
-#include "graphics.h"
-#include "shrooms-vb-core/core/vb.h"
-
-int runGame(VB *sim, GraphicsContext *gfx);
-
-#endif

graphics.c

@@ -1,92 +0,0 @@
-#include <graphics.h>
-
-static void copyScreenTexture(uint8_t *dst, const uint8_t *src, int pitch) {
-    int x, y, i;
-    uint8_t color;
-    int delta = pitch / 384;
-    for (y = 0; y < 224; ++y) {
-        for (x = 0; x < 384; x += 1) {
-            color = src[(y * 384) + x];
-            for (i = 0; i < delta; ++i) {
-                dst[(y * pitch) + (x * delta) + i] = color;
-            }
-        }
-    }
-}
-
-int gfxInit(GraphicsContext *gfx) {
-    gfx->window = SDL_CreateWindow("Shrooms VB",
-        SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
-        1536, 896, SDL_WINDOW_SHOWN | SDL_WINDOW_ALLOW_HIGHDPI);
-    if (!gfx->window) {
-        fprintf(stderr, "Error creating window: %s\n", SDL_GetError());
-        return 1;
-    }
-
-    gfx->renderer = SDL_CreateRenderer(gfx->window, -1, 0);
-    if (!gfx->renderer) {
-        fprintf(stderr, "Error creating renderer: %s\n", SDL_GetError());
-        goto cleanup_window;
-    }
-
-    gfx->winSurface = SDL_GetWindowSurface(gfx->window);
-    if (!gfx->winSurface) {
-        fprintf(stderr, "Error getting surface: %s\n", SDL_GetError());
-        goto cleanup_window;
-    }
-
-    gfx->leftEye = SDL_CreateTexture(gfx->renderer, SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STREAMING, 384, 224);
-    if (!gfx->leftEye) {
-        fprintf(stderr, "Error creating left eye texture: %s\n", SDL_GetError());
-        goto cleanup_window;
-    }
-    SDL_SetTextureColorMod(gfx->leftEye, 0xff, 0, 0);
-
-    gfx->rightEye = SDL_CreateTexture(gfx->renderer, SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STREAMING, 384, 224);
-    if (!gfx->rightEye) {
-        fprintf(stderr, "Error creating left eye texture: %s\n", SDL_GetError());
-        goto cleanup_left_eye;
-    }
-    SDL_SetTextureColorMod(gfx->rightEye, 0, 0xc6, 0xf0);
-    SDL_SetTextureBlendMode(gfx->rightEye, SDL_BLENDMODE_ADD);
-
-    return 0;
-
-cleanup_left_eye:
-    SDL_DestroyTexture(gfx->leftEye);
-cleanup_window:
-    SDL_DestroyWindow(gfx->window);
-    return 1;
-}
-
-void gfxDestroy(GraphicsContext *gfx) {
-    SDL_DestroyTexture(gfx->rightEye);
-    SDL_DestroyTexture(gfx->leftEye);
-    SDL_DestroyWindow(gfx->window);
-}
-
-static void gfxUpdateEye(SDL_Texture *eye, const uint8_t *bytes) {
-    void *target;
-    int pitch;
-    if (SDL_LockTexture(eye, NULL, &target, &pitch)) {
-        fprintf(stderr, "Error locking buffer for eye: %s\n", SDL_GetError());
-        return;
-    }
-    copyScreenTexture(target, bytes, pitch);
-    SDL_UnlockTexture(eye);
-}
-
-void gfxUpdateLeftEye(GraphicsContext *gfx, const uint8_t *bytes) {
-    gfxUpdateEye(gfx->leftEye, bytes);
-}
-void gfxUpdateRightEye(GraphicsContext *gfx, const uint8_t *bytes) {
-    gfxUpdateEye(gfx->rightEye, bytes);
-}
-
-void gfxRender(GraphicsContext *gfx) {
-    SDL_RenderClear(gfx->renderer);
-    SDL_RenderCopy(gfx->renderer, gfx->leftEye, NULL, NULL);
-    SDL_RenderCopy(gfx->renderer, gfx->rightEye, NULL, NULL);
-    SDL_RenderPresent(gfx->renderer);
-}
-

graphics.h

@@ -1,22 +0,0 @@
-#ifndef SHROOMS_VB_NATIVE_GRAPHICS_
-#define SHROOMS_VB_NATIVE_GRAPHICS_
-
-#include <SDL2/SDL.h>
-
-typedef struct {
-    SDL_Window *window;
-    SDL_Surface *winSurface;
-    SDL_Renderer *renderer;
-    SDL_Texture *leftEye;
-    SDL_Texture *rightEye;
-} GraphicsContext;
-
-int gfxInit(GraphicsContext *gfx);
-void gfxDestroy(GraphicsContext *gfx);
-
-void gfxUpdateLeftEye(GraphicsContext *gfx, const uint8_t *bytes);
-void gfxUpdateRightEye(GraphicsContext *gfx, const uint8_t *bytes);
-
-void gfxRender(GraphicsContext *gfx);
-
-#endif

main.c

@@ -1,85 +0,0 @@
-#include <cli.h>
-#include <game.h>
-#include <graphics.h>
-#include <SDL2/SDL.h>
-#include "shrooms-vb-core/core/vb.h"
-#include <stdio.h>
-
-uint8_t *readROM(char *filename, uint32_t *size) {
-    FILE *file = fopen(filename, "rb");
-    uint8_t *rom;
-    long filesize;
-
-    if (!file) {
-        perror("could not open file");
-        return NULL;
-    }
-
-    if (fseek(file, 0, SEEK_END)) {
-        perror("could not seek file end");
-        return NULL;
-    }
-    filesize = ftell(file);
-    if (filesize == -1) {
-        perror("could not read file size");
-        return NULL;
-    }
-    if (fseek(file, 0, SEEK_SET)) {
-        perror("could not seek file start");
-        return NULL;
-    }
-
-    *size = (uint32_t) filesize;
-    rom = malloc(*size);
-    if (!rom) {
-        perror("could not allocate ROM");
-        return NULL;
-    }
-    fread(rom, 1, *size, file);
-    if (ferror(file)) {
-        perror("could not read file");
-        return NULL;
-    }
-    if (fclose(file)) {
-        perror("could not close file");
-        return NULL;
-    }
-
-    return rom;
-}
-
-int main(int argc, char **argv) {
-    VB *sim;
-    uint8_t *rom;
-    uint32_t romSize;
-    GraphicsContext gfx;
-    CLIArgs args;
-    int status;
-
-    if (parseCLIArgs(argc, argv, &args)) {
-        return 1;
-    }
-    
-    rom = readROM(args.filename, &romSize);
-    if (!rom) {
-        return 1;
-    }
-
-    sim = malloc(vbSizeOf());
-    vbInit(sim);
-    vbSetCartROM(sim, rom, romSize);
-
-    if (SDL_Init(SDL_INIT_EVERYTHING)) {
-        fprintf(stderr, "Error initializing SDL: %s\n", SDL_GetError());
-        return 1;
-    }
-
-    if (gfxInit(&gfx)) {
-        SDL_Quit();
-        return 1;
-    }
-
-    status = runGame(sim, &gfx);
-    SDL_Quit();
-    return status;
-}

makefile

@@ -1,48 +0,0 @@
-CC?=gcc
-LD?=ld
-SHROOMSFLAGS=shrooms-vb-core/core/vb.c -I shrooms-vb-core/core
-msys_version := $(if $(findstring Msys, $(shell uname -o)),$(word 1, $(subst ., ,$(shell uname -r))),0)
-
-ifeq ($(msys_version), 0)
-SDL2FLAGS=$(shell pkg-config sdl2 --cflags --libs)
-BINLINKFLAGS=-z noexecstack
-else
-SDL2FLAGS=$(shell pkg-config sdl2 --cflags --libs) -mwindows -mconsole
-BINLINKFLAGS=
-endif
-
-.PHONY: clean build
-clean:
-	@rm -rf shrooms-vb output
-
-CFILES := $(foreach dir,./,$(notdir $(wildcard $(dir)/*.c)))
-BINFILES := $(foreach dir,assets/,$(notdir $(wildcard $(dir)/*.bin)))
-
-COBJS := $(CFILES:%.c=output/%.o)
-SHROOMSOBJS := output/vb.o
-BINOBJS := $(BINFILES:%.bin=output/%.o)
-
-OFILES := $(COBJS) $(SHROOMSOBJS) $(BINOBJS)
-
-output/%.o: %.c
-	@mkdir -p output
-	@$(CC) -c -o $@ $< -I . \
-		-I shrooms-vb-core/core $(SDL2FLAGS) \
-		-O3 -flto -fno-strict-aliasing \
-		-Werror -std=c90 -Wall -Wextra -Wpedantic
-
-output/vb.o: shrooms-vb-core/core/vb.c
-	@mkdir -p output
-	@$(CC) -c -o $@ $< -I . \
-		-I shrooms-vb-core/core $(SDL2FLAGS) \
-		-O3 -flto -fno-strict-aliasing \
-		-Werror -std=c90 -Wall -Wextra -Wpedantic
-
-output/%.o: assets/%.bin
-	@mkdir -p output
-	@$(LD) -r -b binary $(BINLINKFLAGS) -o $@ $<
-
-shrooms-vb: $(OFILES)
-	@$(CC) -o $@ $(OFILES) $(SDL2FLAGS) -flto
-
-build: shrooms-vb

scripts/do-bundle.sh

@@ -0,0 +1,35 @@
+# Set everything up
+rm -rf output
+mkdir -p output
+cargo clean
+
+# Build for linux
+cargo build --release
+cp target/release/lemur output/lemur-linux
+
+# Bundle for Linux
+cargo bundle --release --format deb
+cp target/release/bundle/deb/*.deb output
+
+# Build for Windows
+cargo build --release --target x86_64-pc-windows-msvc
+cp target/x86_64-pc-windows-msvc/release/lemur.exe output
+
+# Build for MacOS Intel
+cargo build --release --target x86_64-apple-darwin
+cp target/x86_64-apple-darwin/release/lemur output/lemur-osx-intel
+
+# Bundle for MacOS Intel
+cargo bundle --release --target x86_64-apple-darwin --format osx
+genisoimage -V lemur -D -R -apple -no-pad -o output/Lemur-Intel.dmg target/x86_64-apple-darwin/release/bundle/osx
+
+# Build for MacOS Apple Silicon
+cargo build --release --target aarch64-apple-darwin
+cp target/aarch64-apple-darwin/release/lemur output/lemur-osx-apple-silicon
+
+# Bundle for MacOS Apple Silicon
+cargo bundle --release --target aarch64-apple-darwin --format osx
+genisoimage -V lemur -D -R -apple -no-pad -o output/Lemur-Apple-Silicon.dmg target/aarch64-apple-darwin/release/bundle/osx
+
+# Clean up after ourselves
+cargo clean

scripts/release.sh

@@ -0,0 +1,72 @@
+set -e
+version=$(cat Cargo.toml | sed -n -e '/version/ {s/.* = *//p;q}' | tr -d '"')
+
+read -p "You wanted to release $version, right? [Y/n] " -n 1 -r
+echo
+case "$REPLY" in
+    n|N ) exit 1;;
+esac
+
+if [ -z "${RELEASE_TOKEN}" ]; then
+    echo "Please set the RELEASE_TOKEN env var."
+    exit 1
+fi
+if ! command -v curl 2>&1 >/dev/null; then
+    echo "Please install curl."
+    exit 1
+fi
+if ! command -v jq 2>&1 >/dev/null; then
+    echo "Please install jq."
+    exit 1
+fi
+if ! command -v docker 2>&1 >/dev/null; then
+    echo "Please install docker."
+    exit 1
+fi
+
+docker build -f build.Dockerfile -t lemur-build .
+MSYS_NO_PATHCONV=1 docker run -it --rm -v .:/app -w /app --entrypoint bash lemur-build /app/scripts/do-bundle.sh
+
+body=$(cat <<EOF
+## How to install
+
+The emulator can be found in the "Downloads" section of this release.
+
+### Windows users
+
+Download \`lemur.exe\`.
+
+### MacOS users
+
+If your Mac uses an Intel processor, download and install \`Lemur-Intel.dmg\`.
+
+If it uses Apple Silicon, download and install \`Lemur-Apple-Silicon.dmg\`.
+
+If you're not sure which to choose, use [this guide](https://support.apple.com/en-us/116943) to find out.
+
+### Linux users
+
+You can either download and run \`lemur-linux\`, or download and install the attached .deb file.
+EOF
+)
+
+payload=$(cat <<EOF
+{
+  "body": $(echo "$body" | jq -Rsa .),
+  "draft": false,
+  "name": "v${version}",
+  "prerelease": false,
+  "tag_name": "v${version}"
+}
+EOF
+)
+
+echo "Creating release..."
+response=$(curl -s --json "$payload" "https://git.virtual-boy.com/api/v1/repos/PVB/lemur/releases?token=$RELEASE_TOKEN")
+echo "$response"
+upload_url=$(echo "$response" | jq -r '.upload_url')
+for file in output/*; do
+    echo "Uploading $(basename "$file")..."
+    upload_res=$(curl -s -F "attachment=@$file" "$upload_url?name=$(basename "$file")&token=$RELEASE_TOKEN")
+    echo "$upload_res"
+done

src/app.rs

@@ -0,0 +1,512 @@
+use std::{collections::HashSet, num::NonZero, sync::Arc, thread, time::Duration};
+
+use egui::{
+    ahash::{HashMap, HashMapExt},
+    Context, FontData, FontDefinitions, FontFamily, IconData, TextWrapMode, ViewportBuilder,
+    ViewportCommand, ViewportId, ViewportInfo,
+};
+use gilrs::{EventType, Gilrs};
+use tracing::{error, warn};
+use winit::{
+    application::ApplicationHandler,
+    event::WindowEvent,
+    event_loop::{ActiveEventLoop, EventLoopProxy},
+    window::Window,
+};
+
+use crate::{
+    controller::ControllerManager,
+    emulator::{EmulatorClient, EmulatorCommand, SimId},
+    input::MappingProvider,
+    persistence::Persistence,
+    window::{AboutWindow, AppWindow, GameWindow, GdbServerWindow, InputWindow},
+};
+
+fn load_icon() -> anyhow::Result<IconData> {
+    let bytes = include_bytes!("../assets/lemur-256x256.png");
+    let img = image::load_from_memory_with_format(bytes, image::ImageFormat::Png)?;
+    let rgba = img.into_rgba8();
+    Ok(IconData {
+        width: rgba.width(),
+        height: rgba.height(),
+        rgba: rgba.into_vec(),
+    })
+}
+
+pub struct Application {
+    icon: Option<Arc<IconData>>,
+    wgpu: WgpuState,
+    client: EmulatorClient,
+    proxy: EventLoopProxy<UserEvent>,
+    mappings: MappingProvider,
+    controllers: ControllerManager,
+    persistence: Persistence,
+    viewports: HashMap<ViewportId, Viewport>,
+    focused: Option<ViewportId>,
+    init_debug_port: Option<u16>,
+}
+
+impl Application {
+    pub fn new(
+        client: EmulatorClient,
+        proxy: EventLoopProxy<UserEvent>,
+        debug_port: Option<u16>,
+    ) -> Self {
+        let wgpu = WgpuState::new();
+        let icon = load_icon().ok().map(Arc::new);
+        let persistence = Persistence::new();
+        let mappings = MappingProvider::new(persistence.clone());
+        let controllers = ControllerManager::new(client.clone(), &mappings);
+        {
+            let mappings = mappings.clone();
+            let proxy = proxy.clone();
+            thread::spawn(|| process_gamepad_input(mappings, proxy));
+        }
+        Self {
+            icon,
+            wgpu,
+            client,
+            proxy,
+            mappings,
+            controllers,
+            persistence,
+            viewports: HashMap::new(),
+            focused: None,
+            init_debug_port: debug_port,
+        }
+    }
+
+    fn open(&mut self, event_loop: &ActiveEventLoop, window: Box<dyn AppWindow>) {
+        let viewport_id = window.viewport_id();
+        if self.viewports.contains_key(&viewport_id) {
+            return;
+        }
+        self.viewports.insert(
+            viewport_id,
+            Viewport::new(event_loop, &self.wgpu, self.icon.clone(), window),
+        );
+    }
+}
+
+impl ApplicationHandler<UserEvent> for Application {
+    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
+        if let Some(port) = self.init_debug_port {
+            let mut server =
+                GdbServerWindow::new(SimId::Player1, self.client.clone(), self.proxy.clone());
+            server.launch(port);
+            self.open(event_loop, Box::new(server));
+        }
+        let app = GameWindow::new(
+            self.client.clone(),
+            self.proxy.clone(),
+            self.persistence.clone(),
+            SimId::Player1,
+        );
+        self.open(event_loop, Box::new(app));
+    }
+
+    fn window_event(
+        &mut self,
+        event_loop: &ActiveEventLoop,
+        window_id: winit::window::WindowId,
+        event: WindowEvent,
+    ) {
+        let Some(viewport) = self
+            .viewports
+            .values_mut()
+            .find(|v| v.window.id() == window_id)
+        else {
+            return;
+        };
+        let viewport_id = viewport.id();
+        match &event {
+            WindowEvent::KeyboardInput { event, .. } => {
+                self.controllers.handle_key_event(event);
+                viewport.app.handle_key_event(event);
+            }
+            WindowEvent::Focused(new_focused) => {
+                self.focused = new_focused.then_some(viewport_id);
+            }
+            _ => {}
+        }
+        let mut queue_redraw = false;
+        let mut inactive_viewports = HashSet::new();
+        match viewport.on_window_event(event) {
+            Some(Action::Redraw) => {
+                for viewport in self.viewports.values_mut() {
+                    match viewport.redraw(event_loop) {
+                        Some(Action::Redraw) => {
+                            queue_redraw = true;
+                        }
+                        Some(Action::Close) => {
+                            inactive_viewports.insert(viewport.id());
+                        }
+                        None => {}
+                    }
+                }
+            }
+            Some(Action::Close) => {
+                inactive_viewports.insert(viewport_id);
+            }
+            None => {}
+        }
+        self.viewports
+            .retain(|k, _| !inactive_viewports.contains(k));
+        match self.viewports.get(&ViewportId::ROOT) {
+            Some(viewport) => {
+                if queue_redraw {
+                    viewport.window.request_redraw();
+                }
+            }
+            None => event_loop.exit(),
+        }
+    }
+
+    fn device_event(
+        &mut self,
+        _event_loop: &ActiveEventLoop,
+        _device_id: winit::event::DeviceId,
+        event: winit::event::DeviceEvent,
+    ) {
+        if let winit::event::DeviceEvent::MouseMotion { delta } = event {
+            let Some(viewport) = self
+                .focused
+                .as_ref()
+                .and_then(|id| self.viewports.get_mut(id))
+            else {
+                return;
+            };
+            viewport.state.on_mouse_motion(delta);
+        }
+    }
+
+    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: UserEvent) {
+        match event {
+            UserEvent::GamepadEvent(event) => {
+                self.controllers.handle_gamepad_event(&event);
+                let Some(viewport) = self
+                    .focused
+                    .as_ref()
+                    .and_then(|id| self.viewports.get_mut(id))
+                else {
+                    return;
+                };
+                viewport.app.handle_gamepad_event(&event);
+            }
+            UserEvent::OpenAbout => {
+                let about = AboutWindow;
+                self.open(event_loop, Box::new(about));
+            }
+            UserEvent::OpenDebugger(sim_id) => {
+                let debugger =
+                    GdbServerWindow::new(sim_id, self.client.clone(), self.proxy.clone());
+                self.open(event_loop, Box::new(debugger));
+            }
+            UserEvent::OpenInput => {
+                let input = InputWindow::new(self.mappings.clone());
+                self.open(event_loop, Box::new(input));
+            }
+            UserEvent::OpenPlayer2 => {
+                let p2 = GameWindow::new(
+                    self.client.clone(),
+                    self.proxy.clone(),
+                    self.persistence.clone(),
+                    SimId::Player2,
+                );
+                self.open(event_loop, Box::new(p2));
+            }
+            UserEvent::Quit(sim_id) => {
+                self.viewports
+                    .retain(|_, viewport| viewport.app.sim_id() != sim_id);
+                if !self.viewports.contains_key(&ViewportId::ROOT) {
+                    event_loop.exit();
+                }
+            }
+        }
+    }
+
+    fn about_to_wait(&mut self, _event_loop: &ActiveEventLoop) {
+        if let Some(viewport) = self.viewports.get(&ViewportId::ROOT) {
+            viewport.window.request_redraw();
+        }
+    }
+
+    fn exiting(&mut self, _event_loop: &ActiveEventLoop) {
+        let (sender, receiver) = oneshot::channel();
+        if self.client.send_command(EmulatorCommand::Exit(sender)) {
+            if let Err(error) = receiver.recv_timeout(Duration::from_secs(5)) {
+                error!(%error, "could not gracefully exit.");
+            }
+        }
+    }
+}
+
+struct WgpuState {
+    instance: Arc<wgpu::Instance>,
+    adapter: Arc<wgpu::Adapter>,
+    device: Arc<wgpu::Device>,
+    queue: Arc<wgpu::Queue>,
+}
+
+impl WgpuState {
+    fn new() -> Self {
+        let egui_wgpu::WgpuConfiguration {
+            wgpu_setup:
+                egui_wgpu::WgpuSetup::CreateNew {
+                    #[allow(unused)]
+                    supported_backends,
+                    device_descriptor,
+                    ..
+                },
+            ..
+        } = egui_wgpu::WgpuConfiguration::default()
+        else {
+            panic!("required fields not found")
+        };
+        #[cfg(windows)]
+        let supported_backends = wgpu::util::backend_bits_from_env()
+            .unwrap_or((wgpu::Backends::PRIMARY | wgpu::Backends::GL) - wgpu::Backends::VULKAN);
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
+            backends: supported_backends,
+            ..wgpu::InstanceDescriptor::default()
+        });
+
+        let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
+            power_preference: wgpu::PowerPreference::HighPerformance,
+            compatible_surface: None,
+            force_fallback_adapter: false,
+        }))
+        .expect("could not create adapter");
+
+        let trace_path = std::env::var("WGPU_TRACE");
+        let (device, queue) = pollster::block_on(adapter.request_device(
+            &(*device_descriptor)(&adapter),
+            trace_path.ok().as_ref().map(std::path::Path::new),
+        ))
+        .expect("could not request device");
+        Self {
+            instance: Arc::new(instance),
+            adapter: Arc::new(adapter),
+            device: Arc::new(device),
+            queue: Arc::new(queue),
+        }
+    }
+}
+
+struct Viewport {
+    painter: egui_wgpu::winit::Painter,
+    ctx: Context,
+    info: ViewportInfo,
+    commands: Vec<ViewportCommand>,
+    builder: ViewportBuilder,
+    window: Arc<Window>,
+    state: egui_winit::State,
+    app: Box<dyn AppWindow>,
+}
+impl Viewport {
+    pub fn new(
+        event_loop: &ActiveEventLoop,
+        wgpu: &WgpuState,
+        icon: Option<Arc<IconData>>,
+        mut app: Box<dyn AppWindow>,
+    ) -> Self {
+        let ctx = Context::default();
+        let mut fonts = FontDefinitions::default();
+        fonts.font_data.insert(
+            "Selawik".into(),
+            Arc::new(FontData::from_static(include_bytes!(
+                "../assets/selawik.ttf"
+            ))),
+        );
+        fonts
+            .families
+            .get_mut(&FontFamily::Proportional)
+            .unwrap()
+            .insert(0, "Selawik".into());
+        ctx.set_fonts(fonts);
+        ctx.style_mut(|s| {
+            s.wrap_mode = Some(TextWrapMode::Extend);
+            s.visuals.menu_rounding = Default::default();
+        });
+        egui_extras::install_image_loaders(&ctx);
+
+        let wgpu_config = egui_wgpu::WgpuConfiguration {
+            present_mode: wgpu::PresentMode::AutoNoVsync,
+            wgpu_setup: egui_wgpu::WgpuSetup::Existing {
+                instance: wgpu.instance.clone(),
+                adapter: wgpu.adapter.clone(),
+                device: wgpu.device.clone(),
+                queue: wgpu.queue.clone(),
+            },
+            ..egui_wgpu::WgpuConfiguration::default()
+        };
+
+        let mut painter =
+            egui_wgpu::winit::Painter::new(ctx.clone(), wgpu_config, 1, None, false, true);
+
+        let mut info = ViewportInfo::default();
+        let mut builder = app.initial_viewport();
+        if let Some(icon) = icon {
+            builder = builder.with_icon(icon);
+        }
+        let (window, state) = create_window_and_state(&ctx, event_loop, &builder, &mut painter);
+        egui_winit::update_viewport_info(&mut info, &ctx, &window, true);
+
+        app.on_init(painter.render_state().as_ref().unwrap());
+        Self {
+            painter,
+            ctx,
+            info,
+            commands: vec![],
+            builder,
+            window,
+            state,
+            app,
+        }
+    }
+
+    pub fn id(&self) -> ViewportId {
+        self.app.viewport_id()
+    }
+
+    pub fn on_window_event(&mut self, event: WindowEvent) -> Option<Action> {
+        let response = self.state.on_window_event(&self.window, &event);
+        egui_winit::update_viewport_info(
+            &mut self.info,
+            self.state.egui_ctx(),
+            &self.window,
+            false,
+        );
+
+        match event {
+            WindowEvent::RedrawRequested => Some(Action::Redraw),
+            WindowEvent::CloseRequested => Some(Action::Close),
+            WindowEvent::Resized(size) => {
+                let (Some(width), Some(height)) =
+                    (NonZero::new(size.width), NonZero::new(size.height))
+                else {
+                    return None;
+                };
+                self.painter
+                    .on_window_resized(ViewportId::ROOT, width, height);
+                None
+            }
+            _ if response.repaint => Some(Action::Redraw),
+            _ => None,
+        }
+    }
+
+    fn redraw(&mut self, event_loop: &ActiveEventLoop) -> Option<Action> {
+        let mut input = self.state.take_egui_input(&self.window);
+        input.viewports = std::iter::once((ViewportId::ROOT, self.info.clone())).collect();
+        let mut output = self.ctx.run(input, |ctx| {
+            self.app.show(ctx);
+        });
+        let clipped_primitives = self.ctx.tessellate(output.shapes, output.pixels_per_point);
+        self.painter.paint_and_update_textures(
+            ViewportId::ROOT,
+            output.pixels_per_point,
+            [0.0, 0.0, 0.0, 0.0],
+            &clipped_primitives,
+            &output.textures_delta,
+            vec![],
+        );
+
+        self.state
+            .handle_platform_output(&self.window, output.platform_output);
+
+        let Some(mut viewport_output) = output.viewport_output.remove(&ViewportId::ROOT) else {
+            return Some(Action::Close);
+        };
+
+        let (mut deferred_commands, recreate) = self.builder.patch(viewport_output.builder);
+        if recreate {
+            let (window, state) =
+                create_window_and_state(&self.ctx, event_loop, &self.builder, &mut self.painter);
+            egui_winit::update_viewport_info(&mut self.info, &self.ctx, &window, true);
+            self.window = window;
+            self.state = state;
+        }
+        self.commands.append(&mut deferred_commands);
+        self.commands.append(&mut viewport_output.commands);
+        egui_winit::process_viewport_commands(
+            &self.ctx,
+            &mut self.info,
+            std::mem::take(&mut self.commands),
+            &self.window,
+            &mut HashSet::default(),
+        );
+
+        if self.info.close_requested() {
+            Some(Action::Close)
+        } else {
+            Some(Action::Redraw)
+        }
+    }
+}
+
+impl Drop for Viewport {
+    fn drop(&mut self) {
+        self.app.on_destroy();
+    }
+}
+
+#[derive(Debug)]
+pub enum UserEvent {
+    GamepadEvent(gilrs::Event),
+    OpenAbout,
+    OpenDebugger(SimId),
+    OpenInput,
+    OpenPlayer2,
+    Quit(SimId),
+}
+
+pub enum Action {
+    Redraw,
+    Close,
+}
+
+fn create_window_and_state(
+    ctx: &Context,
+    event_loop: &ActiveEventLoop,
+    builder: &ViewportBuilder,
+    painter: &mut egui_wgpu::winit::Painter,
+) -> (Arc<Window>, egui_winit::State) {
+    pollster::block_on(painter.set_window(ViewportId::ROOT, None)).unwrap();
+    let window = Arc::new(egui_winit::create_window(ctx, event_loop, builder).unwrap());
+    pollster::block_on(painter.set_window(ViewportId::ROOT, Some(window.clone()))).unwrap();
+    let state = egui_winit::State::new(
+        ctx.clone(),
+        ViewportId::ROOT,
+        event_loop,
+        Some(window.scale_factor() as f32),
+        event_loop.system_theme(),
+        painter.max_texture_side(),
+    );
+    (window, state)
+}
+
+fn process_gamepad_input(mappings: MappingProvider, proxy: EventLoopProxy<UserEvent>) {
+    let mut gilrs = match Gilrs::new() {
+        Ok(gilrs) => gilrs,
+        Err(error) => {
+            warn!(%error, "could not connect gamepad listener");
+            return;
+        }
+    };
+    while let Some(event) = gilrs.next_event_blocking(None) {
+        if event.event == EventType::Connected {
+            let Some(gamepad) = gilrs.connected_gamepad(event.id) else {
+                continue;
+            };
+            mappings.handle_gamepad_connect(&gamepad);
+        }
+        if event.event == EventType::Disconnected {
+            mappings.handle_gamepad_disconnect(event.id);
+        }
+        if proxy.send_event(UserEvent::GamepadEvent(event)).is_err() {
+            // main thread has closed! we done
+            return;
+        }
+    }
+}

src/audio.rs

@@ -0,0 +1,104 @@
+use std::time::Duration;
+
+use anyhow::{bail, Result};
+use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
+use itertools::Itertools;
+use rubato::{FftFixedInOut, Resampler};
+use tracing::error;
+
+pub struct Audio {
+    #[allow(unused)]
+    stream: cpal::Stream,
+    sampler: FftFixedInOut<f32>,
+    input_buffer: Vec<Vec<f32>>,
+    output_buffer: Vec<Vec<f32>>,
+    sample_sink: rtrb::Producer<f32>,
+}
+
+impl Audio {
+    pub fn init() -> Result<Self> {
+        let host = cpal::default_host();
+        let Some(device) = host.default_output_device() else {
+            bail!("No output device available");
+        };
+        let Some(config) = device
+            .supported_output_configs()?
+            .find(|c| c.channels() == 2 && c.sample_format().is_float())
+        else {
+            bail!("No suitable output config available");
+        };
+        let mut config = config.with_max_sample_rate().config();
+        let sampler = FftFixedInOut::new(41700, config.sample_rate.0 as usize, 834, 2)?;
+        config.buffer_size = cpal::BufferSize::Fixed(sampler.output_frames_max() as u32);
+
+        let input_buffer = sampler.input_buffer_allocate(true);
+        let output_buffer = sampler.output_buffer_allocate(true);
+        let (sample_sink, mut sample_source) =
+            rtrb::RingBuffer::new(sampler.output_frames_max() * 4);
+
+        let stream = device.build_output_stream(
+            &config,
+            move |data: &mut [f32], _| {
+                let requested = data.len();
+                let chunk = match sample_source.read_chunk(data.len()) {
+                    Ok(c) => c,
+                    Err(rtrb::chunks::ChunkError::TooFewSlots(n)) => {
+                        sample_source.read_chunk(n).unwrap()
+                    }
+                };
+                let len = chunk.len();
+                let (first, second) = chunk.as_slices();
+                data[0..first.len()].copy_from_slice(first);
+                data[first.len()..len].copy_from_slice(second);
+                for rest in &mut data[len..requested] {
+                    *rest = 0.0;
+                }
+                chunk.commit_all();
+            },
+            move |error| error!(%error, "stream error"),
+            None,
+        )?;
+        stream.play()?;
+        Ok(Self {
+            stream,
+            sampler,
+            input_buffer,
+            output_buffer,
+            sample_sink,
+        })
+    }
+
+    pub fn update(&mut self, samples: &[f32]) {
+        for sample in samples.chunks_exact(2) {
+            for (channel, value) in self.input_buffer.iter_mut().zip(sample) {
+                channel.push(*value);
+            }
+            if self.input_buffer[0].len() >= self.sampler.input_frames_next() {
+                let (_, output_samples) = self
+                    .sampler
+                    .process_into_buffer(&self.input_buffer, &mut self.output_buffer, None)
+                    .unwrap();
+
+                let chunk = match self.sample_sink.write_chunk_uninit(output_samples * 2) {
+                    Ok(c) => c,
+                    Err(rtrb::chunks::ChunkError::TooFewSlots(n)) => {
+                        self.sample_sink.write_chunk_uninit(n).unwrap()
+                    }
+                };
+                let interleaved = self.output_buffer[0]
+                    .iter()
+                    .interleave(self.output_buffer[1].iter())
+                    .cloned();
+                chunk.fill_from_iter(interleaved);
+
+                for channel in &mut self.input_buffer {
+                    channel.clear();
+                }
+            }
+        }
+
+        while self.sample_sink.slots() < self.sampler.output_frames_max() * 2 {
+            std::thread::sleep(Duration::from_micros(500));
+        }
+    }
+}

src/controller.rs

@@ -0,0 +1,128 @@
+use std::sync::{Arc, RwLock};
+
+use gilrs::{ev::Code, Event as GamepadEvent, EventType, GamepadId};
+use winit::{
+    event::{ElementState, KeyEvent},
+    keyboard::PhysicalKey,
+};
+
+use crate::{
+    emulator::{EmulatorClient, EmulatorCommand, SimId, VBKey},
+    input::{InputMapping, MappingProvider},
+};
+
+pub struct Controller {
+    pub sim_id: SimId,
+    state: VBKey,
+    mapping: Arc<RwLock<InputMapping>>,
+}
+
+impl Controller {
+    pub fn new(sim_id: SimId, mappings: &MappingProvider) -> Self {
+        Self {
+            sim_id,
+            state: VBKey::SGN,
+            mapping: mappings.for_sim(sim_id).clone(),
+        }
+    }
+
+    pub fn key_event(&mut self, event: &KeyEvent) -> Option<VBKey> {
+        let keys = self.map_keys(&event.physical_key)?;
+        match event.state {
+            ElementState::Pressed => self.update_state(keys, VBKey::empty()),
+            ElementState::Released => self.update_state(VBKey::empty(), keys),
+        }
+    }
+
+    pub fn gamepad_event(&mut self, event: &GamepadEvent) -> Option<VBKey> {
+        let (pressed, released) = match event.event {
+            EventType::ButtonPressed(_, code) => {
+                let mappings = self.map_button(&event.id, &code)?;
+                (mappings, VBKey::empty())
+            }
+            EventType::ButtonReleased(_, code) => {
+                let mappings = self.map_button(&event.id, &code)?;
+                (VBKey::empty(), mappings)
+            }
+            EventType::AxisChanged(_, value, code) => {
+                let (neg, pos) = self.map_axis(&event.id, &code)?;
+                let mut pressed = VBKey::empty();
+                let mut released = VBKey::empty();
+                if value < -0.75 {
+                    pressed = pressed.union(neg);
+                }
+                if value > 0.75 {
+                    pressed = pressed.union(pos);
+                }
+                if value > -0.65 {
+                    released = released.union(neg);
+                }
+                if value < 0.65 {
+                    released = released.union(pos);
+                }
+                (pressed, released)
+            }
+            _ => {
+                return None;
+            }
+        };
+        self.update_state(pressed, released)
+    }
+
+    fn update_state(&mut self, pressed: VBKey, released: VBKey) -> Option<VBKey> {
+        let old_state = self.state;
+        self.state = self.state.union(pressed).difference(released);
+        if self.state != old_state {
+            Some(self.state)
+        } else {
+            None
+        }
+    }
+
+    fn map_keys(&self, key: &PhysicalKey) -> Option<VBKey> {
+        self.mapping.read().unwrap().map_keyboard(key)
+    }
+
+    fn map_button(&self, id: &GamepadId, code: &Code) -> Option<VBKey> {
+        self.mapping.read().unwrap().map_button(id, code)
+    }
+
+    fn map_axis(&self, id: &GamepadId, code: &Code) -> Option<(VBKey, VBKey)> {
+        self.mapping.read().unwrap().map_axis(id, code)
+    }
+}
+
+pub struct ControllerManager {
+    client: EmulatorClient,
+    controllers: [Controller; 2],
+}
+
+impl ControllerManager {
+    pub fn new(client: EmulatorClient, mappings: &MappingProvider) -> Self {
+        Self {
+            client,
+            controllers: [
+                Controller::new(SimId::Player1, mappings),
+                Controller::new(SimId::Player2, mappings),
+            ],
+        }
+    }
+
+    pub fn handle_key_event(&mut self, event: &KeyEvent) {
+        for controller in &mut self.controllers {
+            if let Some(pressed) = controller.key_event(event) {
+                self.client
+                    .send_command(EmulatorCommand::SetKeys(controller.sim_id, pressed));
+            }
+        }
+    }
+
+    pub fn handle_gamepad_event(&mut self, event: &GamepadEvent) {
+        for controller in &mut self.controllers {
+            if let Some(pressed) = controller.gamepad_event(event) {
+                self.client
+                    .send_command(EmulatorCommand::SetKeys(controller.sim_id, pressed));
+            }
+        }
+    }
+}

src/emulator.rs

@@ -0,0 +1,735 @@
+use std::{
+    collections::HashMap,
+    fmt::Display,
+    fs::{self, File},
+    io::{Read, Seek, SeekFrom, Write},
+    path::{Path, PathBuf},
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        mpsc::{self, RecvError, TryRecvError},
+        Arc,
+    },
+};
+
+use anyhow::Result;
+use atomic::Atomic;
+use bytemuck::NoUninit;
+use egui_toast::{Toast, ToastKind, ToastOptions};
+use tracing::{error, warn};
+
+use crate::{audio::Audio, graphics::TextureSink};
+use shrooms_vb_core::{Sim, StopReason, EXPECTED_FRAME_SIZE};
+pub use shrooms_vb_core::{VBKey, VBRegister, VBWatchpointType};
+
+mod address_set;
+mod shrooms_vb_core;
+
+#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
+pub enum SimId {
+    Player1,
+    Player2,
+}
+impl SimId {
+    pub const fn values() -> [Self; 2] {
+        [Self::Player1, Self::Player2]
+    }
+    pub const fn to_index(self) -> usize {
+        match self {
+            Self::Player1 => 0,
+            Self::Player2 => 1,
+        }
+    }
+}
+impl Display for SimId {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            Self::Player1 => "Player 1",
+            Self::Player2 => "Player 2",
+        })
+    }
+}
+
+struct Cart {
+    rom_path: PathBuf,
+    rom: Vec<u8>,
+    sram_file: File,
+    sram: Vec<u8>,
+}
+
+impl Cart {
+    fn load(rom_path: &Path, sim_id: SimId) -> Result<Self> {
+        let rom = fs::read(rom_path)?;
+
+        let mut sram_file = File::options()
+            .read(true)
+            .write(true)
+            .create(true)
+            .truncate(false)
+            .open(sram_path(rom_path, sim_id))?;
+        sram_file.set_len(8 * 1024)?;
+
+        let mut sram = vec![];
+        sram_file.read_to_end(&mut sram)?;
+        Ok(Cart {
+            rom_path: rom_path.to_path_buf(),
+            rom,
+            sram_file,
+            sram,
+        })
+    }
+}
+
+fn sram_path(rom_path: &Path, sim_id: SimId) -> PathBuf {
+    match sim_id {
+        SimId::Player1 => rom_path.with_extension("p1.sram"),
+        SimId::Player2 => rom_path.with_extension("p2.sram"),
+    }
+}
+
+pub struct EmulatorBuilder {
+    rom: Option<PathBuf>,
+    commands: mpsc::Receiver<EmulatorCommand>,
+    sim_state: Arc<[Atomic<SimState>; 2]>,
+    state: Arc<Atomic<EmulatorState>>,
+    audio_on: Arc<[AtomicBool; 2]>,
+    linked: Arc<AtomicBool>,
+    start_paused: bool,
+}
+
+impl EmulatorBuilder {
+    pub fn new() -> (Self, EmulatorClient) {
+        let (queue, commands) = mpsc::channel();
+        let builder = Self {
+            rom: None,
+            commands,
+            sim_state: Arc::new([
+                Atomic::new(SimState::Uninitialized),
+                Atomic::new(SimState::Uninitialized),
+            ]),
+            state: Arc::new(Atomic::new(EmulatorState::Paused)),
+            audio_on: Arc::new([AtomicBool::new(true), AtomicBool::new(true)]),
+            linked: Arc::new(AtomicBool::new(false)),
+            start_paused: false,
+        };
+        let client = EmulatorClient {
+            queue,
+            sim_state: builder.sim_state.clone(),
+            state: builder.state.clone(),
+            audio_on: builder.audio_on.clone(),
+            linked: builder.linked.clone(),
+        };
+        (builder, client)
+    }
+
+    pub fn with_rom(self, path: &Path) -> Self {
+        Self {
+            rom: Some(path.into()),
+            ..self
+        }
+    }
+
+    pub fn start_paused(self, paused: bool) -> Self {
+        Self {
+            start_paused: paused,
+            ..self
+        }
+    }
+
+    pub fn build(self) -> Result<Emulator> {
+        let mut emulator = Emulator::new(
+            self.commands,
+            self.sim_state,
+            self.state,
+            self.audio_on,
+            self.linked,
+        )?;
+        if let Some(path) = self.rom {
+            emulator.load_cart(SimId::Player1, &path)?;
+        }
+        if self.start_paused {
+            emulator.pause_sims()?;
+        }
+        Ok(emulator)
+    }
+}
+
+pub struct Emulator {
+    sims: Vec<Sim>,
+    carts: [Option<Cart>; 2],
+    audio: Audio,
+    commands: mpsc::Receiver<EmulatorCommand>,
+    sim_state: Arc<[Atomic<SimState>; 2]>,
+    state: Arc<Atomic<EmulatorState>>,
+    audio_on: Arc<[AtomicBool; 2]>,
+    linked: Arc<AtomicBool>,
+    renderers: HashMap<SimId, TextureSink>,
+    messages: HashMap<SimId, mpsc::Sender<Toast>>,
+    debuggers: HashMap<SimId, DebugInfo>,
+    eye_contents: Vec<u8>,
+    audio_samples: Vec<f32>,
+}
+
+impl Emulator {
+    fn new(
+        commands: mpsc::Receiver<EmulatorCommand>,
+        sim_state: Arc<[Atomic<SimState>; 2]>,
+        state: Arc<Atomic<EmulatorState>>,
+        audio_on: Arc<[AtomicBool; 2]>,
+        linked: Arc<AtomicBool>,
+    ) -> Result<Self> {
+        Ok(Self {
+            sims: vec![],
+            carts: [None, None],
+            audio: Audio::init()?,
+            commands,
+            sim_state,
+            state,
+            audio_on,
+            linked,
+            renderers: HashMap::new(),
+            messages: HashMap::new(),
+            debuggers: HashMap::new(),
+            eye_contents: vec![0u8; 384 * 224 * 2],
+            audio_samples: Vec::with_capacity(EXPECTED_FRAME_SIZE),
+        })
+    }
+
+    pub fn load_cart(&mut self, sim_id: SimId, path: &Path) -> Result<()> {
+        let cart = Cart::load(path, sim_id)?;
+        self.reset_sim(sim_id, Some(cart))?;
+        Ok(())
+    }
+
+    pub fn start_second_sim(&mut self, rom: Option<PathBuf>) -> Result<()> {
+        let rom_path = if let Some(path) = rom {
+            Some(path)
+        } else {
+            self.carts[0].as_ref().map(|c| c.rom_path.clone())
+        };
+        let cart = match rom_path {
+            Some(rom_path) => Some(Cart::load(&rom_path, SimId::Player2)?),
+            None => None,
+        };
+        self.reset_sim(SimId::Player2, cart)?;
+        self.link_sims();
+        Ok(())
+    }
+
+    fn reset_sim(&mut self, sim_id: SimId, new_cart: Option<Cart>) -> Result<()> {
+        self.save_sram(sim_id)?;
+
+        let index = sim_id.to_index();
+        while self.sims.len() <= index {
+            self.sims.push(Sim::new());
+            self.sim_state[index].store(SimState::NoGame, Ordering::Release);
+        }
+        let sim = &mut self.sims[index];
+        sim.reset();
+        if let Some(cart) = new_cart {
+            sim.load_cart(cart.rom.clone(), cart.sram.clone())?;
+            self.carts[index] = Some(cart);
+            self.sim_state[index].store(SimState::Ready, Ordering::Release);
+        }
+        if self.sim_state[index].load(Ordering::Acquire) == SimState::Ready {
+            self.resume_sims();
+        }
+        Ok(())
+    }
+
+    fn link_sims(&mut self) {
+        let (first, second) = self.sims.split_at_mut(1);
+        let Some(first) = first.first_mut() else {
+            return;
+        };
+        let Some(second) = second.first_mut() else {
+            return;
+        };
+        first.link(second);
+        self.linked.store(true, Ordering::Release);
+    }
+
+    fn unlink_sims(&mut self) {
+        let Some(first) = self.sims.first_mut() else {
+            return;
+        };
+        first.unlink();
+        self.linked.store(false, Ordering::Release);
+    }
+
+    fn pause_sims(&mut self) -> Result<()> {
+        if self
+            .state
+            .compare_exchange(
+                EmulatorState::Running,
+                EmulatorState::Paused,
+                Ordering::AcqRel,
+                Ordering::Relaxed,
+            )
+            .is_ok()
+        {
+            for sim_id in SimId::values() {
+                self.save_sram(sim_id)?;
+            }
+        }
+        Ok(())
+    }
+
+    fn resume_sims(&mut self) {
+        let _ = self.state.compare_exchange(
+            EmulatorState::Paused,
+            EmulatorState::Running,
+            Ordering::AcqRel,
+            Ordering::Relaxed,
+        );
+    }
+
+    fn save_sram(&mut self, sim_id: SimId) -> Result<()> {
+        let sim = self.sims.get_mut(sim_id.to_index());
+        let cart = self.carts[sim_id.to_index()].as_mut();
+        if let (Some(sim), Some(cart)) = (sim, cart) {
+            sim.read_sram(&mut cart.sram);
+            cart.sram_file.seek(SeekFrom::Start(0))?;
+            cart.sram_file.write_all(&cart.sram)?;
+        }
+        Ok(())
+    }
+
+    pub fn stop_second_sim(&mut self) -> Result<()> {
+        self.save_sram(SimId::Player2)?;
+        self.renderers.remove(&SimId::Player2);
+        self.sims.truncate(1);
+        self.sim_state[SimId::Player2.to_index()].store(SimState::Uninitialized, Ordering::Release);
+        self.stop_debugging(SimId::Player2);
+        self.linked.store(false, Ordering::Release);
+        Ok(())
+    }
+
+    fn start_debugging(&mut self, sim_id: SimId, sender: DebugSender) {
+        if self.sim_state[sim_id.to_index()].load(Ordering::Acquire) != SimState::Ready {
+            // Can't debug unless a game is connected
+            return;
+        }
+        let debug = DebugInfo {
+            sender,
+            stop_reason: Some(DebugStopReason::Paused),
+        };
+        self.debuggers.insert(sim_id, debug);
+        self.state
+            .store(EmulatorState::Debugging, Ordering::Release);
+    }
+
+    fn stop_debugging(&mut self, sim_id: SimId) {
+        if let Some(sim) = self.sims.get_mut(sim_id.to_index()) {
+            sim.clear_debug_state();
+        }
+        self.debuggers.remove(&sim_id);
+        if self.debuggers.is_empty() {
+            let _ = self.state.compare_exchange(
+                EmulatorState::Debugging,
+                EmulatorState::Running,
+                Ordering::AcqRel,
+                Ordering::Relaxed,
+            );
+        }
+    }
+
+    fn debug_interrupt(&mut self, sim_id: SimId) {
+        self.debug_stop(sim_id, DebugStopReason::Paused);
+    }
+
+    fn debug_stop(&mut self, sim_id: SimId, reason: DebugStopReason) {
+        let Some(debugger) = self.debuggers.get_mut(&sim_id) else {
+            self.stop_debugging(sim_id);
+            return;
+        };
+        if debugger.stop_reason != Some(reason) {
+            debugger.stop_reason = Some(reason);
+            if debugger.sender.send(DebugEvent::Stopped(reason)).is_err() {
+                self.stop_debugging(sim_id);
+            }
+        }
+    }
+
+    fn debug_continue(&mut self, sim_id: SimId) -> bool {
+        let Some(debugger) = self.debuggers.get_mut(&sim_id) else {
+            self.stop_debugging(sim_id);
+            return false;
+        };
+        debugger.stop_reason = None;
+        true
+    }
+    fn debug_step(&mut self, sim_id: SimId) {
+        if self.debug_continue(sim_id) {
+            let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                return;
+            };
+            sim.step();
+        }
+    }
+
+    pub fn run(&mut self) {
+        loop {
+            let idle = self.tick();
+            if idle {
+                // The game is paused, and we have output all the video/audio we have.
+                // Block the thread until a new command comes in.
+                match self.commands.recv() {
+                    Ok(command) => self.handle_command(command),
+                    Err(RecvError) => {
+                        return;
+                    }
+                }
+            }
+            loop {
+                match self.commands.try_recv() {
+                    Ok(command) => self.handle_command(command),
+                    Err(TryRecvError::Empty) => {
+                        break;
+                    }
+                    Err(TryRecvError::Disconnected) => {
+                        return;
+                    }
+                }
+            }
+        }
+    }
+
+    // returns true if the emulator is "idle" (i.e. this didn't output anything)
+    pub fn tick(&mut self) -> bool {
+        let p1_state = self.sim_state[SimId::Player1.to_index()].load(Ordering::Acquire);
+        let p2_state = self.sim_state[SimId::Player2.to_index()].load(Ordering::Acquire);
+        let state = self.state.load(Ordering::Acquire);
+
+        // Emulation
+        // Don't emulate if the state is "paused", or if any sim is paused in the debugger
+        let running = match state {
+            EmulatorState::Paused => false,
+            EmulatorState::Running => true,
+            EmulatorState::Debugging => self.debuggers.values().all(|d| d.stop_reason.is_none()),
+        };
+        let p1_running = running && p1_state == SimState::Ready;
+        let p2_running = running && p2_state == SimState::Ready;
+        let mut idle = !p1_running && !p2_running;
+        if p1_running && p2_running {
+            Sim::emulate_many(&mut self.sims);
+        } else if p1_running {
+            self.sims[SimId::Player1.to_index()].emulate();
+        } else if p2_running {
+            self.sims[SimId::Player2.to_index()].emulate();
+        }
+
+        // Debug state
+        if state == EmulatorState::Debugging {
+            for sim_id in SimId::values() {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    continue;
+                };
+                if let Some(reason) = sim.stop_reason() {
+                    let stop_reason = match reason {
+                        StopReason::Stepped => DebugStopReason::Trace,
+                        StopReason::Watchpoint(watch, address) => {
+                            DebugStopReason::Watchpoint(watch, address)
+                        }
+                        StopReason::Breakpoint => DebugStopReason::Breakpoint,
+                    };
+                    self.debug_stop(sim_id, stop_reason);
+                }
+            }
+        }
+
+        // Video
+        for sim_id in SimId::values() {
+            let Some(renderer) = self.renderers.get_mut(&sim_id) else {
+                continue;
+            };
+            let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                continue;
+            };
+            if sim.read_pixels(&mut self.eye_contents) {
+                idle = false;
+                if renderer.queue_render(&self.eye_contents).is_err() {
+                    self.renderers.remove(&sim_id);
+                }
+            }
+        }
+
+        // Audio
+        // Audio playback speed is how we keep the emulator running in real time.
+        // Even if we're muted, call `read_samples` to know how many frames of silence to play.
+        let p1_audio =
+            p1_running && self.audio_on[SimId::Player1.to_index()].load(Ordering::Acquire);
+        let p2_audio =
+            p2_running && self.audio_on[SimId::Player2.to_index()].load(Ordering::Acquire);
+        let (p1_weight, p2_weight) = match (p1_audio, p2_audio) {
+            (true, true) => (0.5, 0.5),
+            (true, false) => (1.0, 0.0),
+            (false, true) => (0.0, 1.0),
+            (false, false) => (0.0, 0.0),
+        };
+        if let Some(sim) = self.sims.get_mut(SimId::Player1.to_index()) {
+            sim.read_samples(&mut self.audio_samples, p1_weight);
+        }
+        if let Some(sim) = self.sims.get_mut(SimId::Player2.to_index()) {
+            sim.read_samples(&mut self.audio_samples, p2_weight);
+        }
+        if !self.audio_samples.is_empty() {
+            idle = false;
+        }
+        self.audio.update(&self.audio_samples);
+        self.audio_samples.clear();
+        idle
+    }
+
+    fn handle_command(&mut self, command: EmulatorCommand) {
+        match command {
+            EmulatorCommand::ConnectToSim(sim_id, renderer, messages) => {
+                self.renderers.insert(sim_id, renderer);
+                self.messages.insert(sim_id, messages);
+            }
+            EmulatorCommand::LoadGame(sim_id, path) => {
+                if let Err(error) = self.load_cart(sim_id, &path) {
+                    self.report_error(sim_id, format!("Error loading rom: {error}"));
+                }
+            }
+            EmulatorCommand::StartSecondSim(path) => {
+                if let Err(error) = self.start_second_sim(path) {
+                    self.report_error(
+                        SimId::Player2,
+                        format!("Error starting second sim: {error}"),
+                    );
+                }
+            }
+            EmulatorCommand::StopSecondSim => {
+                if let Err(error) = self.stop_second_sim() {
+                    self.report_error(
+                        SimId::Player2,
+                        format!("Error stopping second sim: {error}"),
+                    );
+                }
+            }
+            EmulatorCommand::Pause => {
+                if let Err(error) = self.pause_sims() {
+                    self.report_error(SimId::Player1, format!("Error pausing: {error}"));
+                }
+            }
+            EmulatorCommand::Resume => {
+                self.resume_sims();
+            }
+            EmulatorCommand::StartDebugging(sim_id, debugger) => {
+                self.start_debugging(sim_id, debugger);
+            }
+            EmulatorCommand::StopDebugging(sim_id) => {
+                self.stop_debugging(sim_id);
+            }
+            EmulatorCommand::DebugInterrupt(sim_id) => {
+                self.debug_interrupt(sim_id);
+            }
+            EmulatorCommand::DebugContinue(sim_id) => {
+                self.debug_continue(sim_id);
+            }
+            EmulatorCommand::DebugStep(sim_id) => {
+                self.debug_step(sim_id);
+            }
+            EmulatorCommand::ReadRegister(sim_id, register, done) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                let value = sim.read_register(register);
+                let _ = done.send(value);
+            }
+            EmulatorCommand::WriteRegister(sim_id, register, value) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.write_register(register, value);
+            }
+            EmulatorCommand::ReadMemory(sim_id, start, length, mut buffer, done) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.read_memory(start, length, &mut buffer);
+                let _ = done.send(buffer);
+            }
+            EmulatorCommand::WriteMemory(sim_id, start, buffer, done) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.write_memory(start, &buffer);
+                let _ = done.send(buffer);
+            }
+            EmulatorCommand::AddBreakpoint(sim_id, address) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.add_breakpoint(address);
+            }
+            EmulatorCommand::RemoveBreakpoint(sim_id, address) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.remove_breakpoint(address);
+            }
+            EmulatorCommand::AddWatchpoint(sim_id, address, length, watch) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.add_watchpoint(address, length, watch);
+            }
+            EmulatorCommand::RemoveWatchpoint(sim_id, address, length, watch) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.remove_watchpoint(address, length, watch);
+            }
+            EmulatorCommand::SetAudioEnabled(p1, p2) => {
+                self.audio_on[SimId::Player1.to_index()].store(p1, Ordering::Release);
+                self.audio_on[SimId::Player2.to_index()].store(p2, Ordering::Release);
+            }
+            EmulatorCommand::Link => {
+                self.link_sims();
+            }
+            EmulatorCommand::Unlink => {
+                self.unlink_sims();
+            }
+            EmulatorCommand::Reset(sim_id) => {
+                if let Err(error) = self.reset_sim(sim_id, None) {
+                    self.report_error(sim_id, format!("Error resetting sim: {error}"));
+                }
+            }
+            EmulatorCommand::SetKeys(sim_id, keys) => {
+                if let Some(sim) = self.sims.get_mut(sim_id.to_index()) {
+                    sim.set_keys(keys);
+                }
+            }
+            EmulatorCommand::Exit(done) => {
+                for sim_id in SimId::values() {
+                    if let Err(error) = self.save_sram(sim_id) {
+                        self.report_error(sim_id, format!("Error saving sram on exit: {error}"));
+                    }
+                }
+                let _ = done.send(());
+            }
+        }
+    }
+
+    fn report_error(&self, sim_id: SimId, message: String) {
+        let messages = self
+            .messages
+            .get(&sim_id)
+            .or_else(|| self.messages.get(&SimId::Player1));
+        if let Some(msg) = messages {
+            let toast = Toast::new()
+                .kind(ToastKind::Error)
+                .options(ToastOptions::default().duration_in_seconds(5.0))
+                .text(&message);
+            if msg.send(toast).is_ok() {
+                return;
+            }
+        }
+        error!("{}", message);
+    }
+}
+
+#[derive(Debug)]
+pub enum EmulatorCommand {
+    ConnectToSim(SimId, TextureSink, mpsc::Sender<Toast>),
+    LoadGame(SimId, PathBuf),
+    StartSecondSim(Option<PathBuf>),
+    StopSecondSim,
+    Pause,
+    Resume,
+    StartDebugging(SimId, DebugSender),
+    StopDebugging(SimId),
+    DebugInterrupt(SimId),
+    DebugContinue(SimId),
+    DebugStep(SimId),
+    ReadRegister(SimId, VBRegister, oneshot::Sender<u32>),
+    WriteRegister(SimId, VBRegister, u32),
+    ReadMemory(SimId, u32, usize, Vec<u8>, oneshot::Sender<Vec<u8>>),
+    WriteMemory(SimId, u32, Vec<u8>, oneshot::Sender<Vec<u8>>),
+    AddBreakpoint(SimId, u32),
+    RemoveBreakpoint(SimId, u32),
+    AddWatchpoint(SimId, u32, usize, VBWatchpointType),
+    RemoveWatchpoint(SimId, u32, usize, VBWatchpointType),
+    SetAudioEnabled(bool, bool),
+    Link,
+    Unlink,
+    Reset(SimId),
+    SetKeys(SimId, VBKey),
+    Exit(oneshot::Sender<()>),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, NoUninit)]
+#[repr(usize)]
+pub enum SimState {
+    Uninitialized,
+    NoGame,
+    Ready,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, NoUninit)]
+#[repr(usize)]
+pub enum EmulatorState {
+    Paused,
+    Running,
+    Debugging,
+}
+
+type DebugSender = tokio::sync::mpsc::UnboundedSender<DebugEvent>;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum DebugStopReason {
+    // We are stepping
+    Trace,
+    // We hit a breakpoint
+    Breakpoint,
+    // We hit a watchpoint
+    Watchpoint(VBWatchpointType, u32),
+    // The debugger told us to pause
+    Paused,
+}
+
+struct DebugInfo {
+    sender: DebugSender,
+    stop_reason: Option<DebugStopReason>,
+}
+
+pub enum DebugEvent {
+    Stopped(DebugStopReason),
+}
+
+#[derive(Clone)]
+pub struct EmulatorClient {
+    queue: mpsc::Sender<EmulatorCommand>,
+    sim_state: Arc<[Atomic<SimState>; 2]>,
+    state: Arc<Atomic<EmulatorState>>,
+    audio_on: Arc<[AtomicBool; 2]>,
+    linked: Arc<AtomicBool>,
+}
+
+impl EmulatorClient {
+    pub fn sim_state(&self, sim_id: SimId) -> SimState {
+        self.sim_state[sim_id.to_index()].load(Ordering::Acquire)
+    }
+    pub fn emulator_state(&self) -> EmulatorState {
+        self.state.load(Ordering::Acquire)
+    }
+    pub fn is_audio_enabled(&self, sim_id: SimId) -> bool {
+        self.audio_on[sim_id.to_index()].load(Ordering::Acquire)
+    }
+    pub fn are_sims_linked(&self) -> bool {
+        self.linked.load(Ordering::Acquire)
+    }
+    pub fn send_command(&self, command: EmulatorCommand) -> bool {
+        match self.queue.send(command) {
+            Ok(()) => true,
+            Err(err) => {
+                warn!(
+                    "could not send command {:?} as emulator is shut down",
+                    err.0
+                );
+                false
+            }
+        }
+    }
+}

src/emulator/address_set.rs

@@ -0,0 +1,270 @@
+use std::{
+    collections::{BTreeMap, BTreeSet},
+    ops::Bound,
+};
+
+#[derive(Debug, Default)]
+pub struct AddressSet {
+    ranges: BTreeSet<(u32, usize)>,
+    bounds: BTreeMap<u32, usize>,
+}
+
+impl AddressSet {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn add(&mut self, address: u32, length: usize) {
+        if length == 0 || !self.ranges.insert((address, length)) {
+            return;
+        }
+        let end = (address as usize)
+            .checked_add(length)
+            .and_then(|e| u32::try_from(e).ok());
+
+        if let Some(end) = end {
+            let val_before = self.bounds.range(..=end).next_back().map_or(0, |(_, &v)| v);
+            self.bounds.insert(end, val_before);
+        }
+
+        let val_before = self
+            .bounds
+            .range(..address)
+            .next_back()
+            .map_or(0, |(_, &v)| v);
+        if let Some(&val_at) = self.bounds.get(&address) {
+            if val_before == val_at + 1 {
+                self.bounds.remove(&address);
+            }
+        } else {
+            self.bounds.insert(address, val_before);
+        }
+
+        let start_bound = Bound::Included(address);
+        let end_bound = match end {
+            Some(e) => Bound::Excluded(e),
+            None => Bound::Unbounded,
+        };
+
+        for (_, val) in self.bounds.range_mut((start_bound, end_bound)) {
+            *val += 1;
+        }
+    }
+
+    pub fn remove(&mut self, address: u32, length: usize) {
+        if !self.ranges.remove(&(address, length)) {
+            return;
+        }
+        let end = (address as usize)
+            .checked_add(length)
+            .and_then(|e| u32::try_from(e).ok());
+
+        if let Some(end) = end {
+            let val_before = self.bounds.range(..end).next_back().map_or(0, |(_, &v)| v);
+            if let Some(&val_at) = self.bounds.get(&end) {
+                if val_at + 1 == val_before {
+                    self.bounds.remove(&end);
+                }
+            } else {
+                self.bounds.insert(end, val_before);
+            }
+        }
+
+        let val_before = self
+            .bounds
+            .range(..address)
+            .next_back()
+            .map_or(0, |(_, &v)| v);
+        if let Some(&val_at) = self.bounds.get(&address) {
+            if val_before + 1 == val_at {
+                self.bounds.remove(&address);
+            }
+        } else {
+            self.bounds.insert(address, val_before);
+        }
+
+        let start_bound = Bound::Included(address);
+        let end_bound = match end {
+            Some(e) => Bound::Excluded(e),
+            None => Bound::Unbounded,
+        };
+
+        for (_, val) in self.bounds.range_mut((start_bound, end_bound)) {
+            *val -= 1;
+        }
+    }
+
+    pub fn clear(&mut self) {
+        self.ranges.clear();
+        self.bounds.clear();
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.bounds.is_empty()
+    }
+
+    pub fn contains(&self, address: u32) -> bool {
+        self.bounds
+            .range(..=address)
+            .next_back()
+            .is_some_and(|(_, &val)| val > 0)
+    }
+
+    pub fn start_of_range_containing(&self, address: u32) -> Option<u32> {
+        if !self.contains(address) {
+            return None;
+        }
+        self.ranges
+            .range(..=(address, usize::MAX))
+            .rev()
+            .find_map(|&(start, length)| {
+                let contains = start <= address
+                    && (start as usize)
+                        .checked_add(length)
+                        .is_none_or(|end| end > address as usize);
+                contains.then_some(start)
+            })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::AddressSet;
+
+    #[test]
+    fn should_not_include_addresses_when_empty() {
+        let set = AddressSet::new();
+        assert!(set.is_empty());
+        assert!(!set.contains(0x13374200));
+        assert_eq!(set.start_of_range_containing(0x13374200), None);
+    }
+
+    #[test]
+    fn should_include_addresses_when_full() {
+        let mut set = AddressSet::new();
+        set.add(0x00000000, 0x100000000);
+        assert!(set.contains(0x13374200));
+        assert_eq!(set.start_of_range_containing(0x13374200), Some(0x00000000));
+    }
+
+    #[test]
+    fn should_ignore_empty_address_ranges() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 0);
+        assert!(set.is_empty());
+        assert!(!set.contains(0x13374200));
+    }
+
+    #[test]
+    fn should_add_addresses_idempotently() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 1);
+        set.add(0x13374200, 1);
+        set.remove(0x13374200, 1);
+        assert!(set.is_empty());
+        assert!(!set.contains(0x13374200));
+    }
+
+    #[test]
+    fn should_remove_addresses_idempotently() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 1);
+        set.remove(0x13374200, 1);
+        set.remove(0x13374200, 1);
+        assert!(set.is_empty());
+        assert!(!set.contains(0x13374200));
+    }
+
+    #[test]
+    fn should_report_address_in_range() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 4);
+        assert!(!set.contains(0x133741ff));
+        for address in 0x13374200..0x13374204 {
+            assert!(set.contains(address));
+        }
+        assert!(!set.contains(0x13374204));
+    }
+
+    #[test]
+    fn should_allow_overlapping_addresses() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 4);
+        set.add(0x13374201, 1);
+        set.add(0x13374202, 2);
+
+        assert!(!set.contains(0x133741ff));
+        for address in 0x13374200..0x13374204 {
+            assert!(set.contains(address));
+        }
+        assert!(!set.contains(0x13374204));
+
+        set.remove(0x13374200, 4);
+        assert!(!set.contains(0x13374200));
+        for address in 0x13374201..0x13374204 {
+            assert!(set.contains(address));
+        }
+        assert!(!set.contains(0x13374204));
+    }
+
+    #[test]
+    fn should_allow_removing_overlapped_address_ranges() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 8);
+        set.add(0x13374204, 8);
+        set.remove(0x13374204, 8);
+
+        for address in 0x13374200..0x13374208 {
+            assert!(set.contains(address));
+        }
+        for address in 0x13374208..0x1337420c {
+            assert!(!set.contains(address));
+        }
+    }
+
+    #[test]
+    fn should_merge_adjacent_ranges() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 4);
+        set.add(0x13374204, 4);
+        set.add(0x13374208, 4);
+        set.add(0x1337420c, 4);
+
+        assert!(!set.contains(0x133741ff));
+        for address in 0x13374200..0x13374210 {
+            assert!(set.contains(address));
+        }
+        assert!(!set.contains(0x13374210));
+
+        set.remove(0x13374200, 4);
+        set.remove(0x13374204, 4);
+        set.remove(0x13374208, 4);
+        set.remove(0x1337420c, 4);
+
+        assert!(set.is_empty());
+        for address in 0x133741ff..=0x13374210 {
+            assert!(!set.contains(address));
+        }
+    }
+
+    #[test]
+    fn should_find_start_of_range() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 4);
+        assert_eq!(set.start_of_range_containing(0x133741ff), None);
+        for address in 0x13374200..0x13374204 {
+            assert_eq!(set.start_of_range_containing(address), Some(0x13374200));
+        }
+        assert_eq!(set.start_of_range_containing(0x13374204), None);
+    }
+
+    #[test]
+    fn should_ignore_ranges_not_containing_address() {
+        let mut set = AddressSet::new();
+        set.add(0x10000000, 1024);
+        set.add(0x30000000, 1024);
+
+        assert!(!set.contains(0x20000000));
+        assert_eq!(set.start_of_range_containing(0x20000000), None);
+    }
+}

src/emulator/shrooms_vb_core.rs

@@ -0,0 +1,638 @@
+use std::{ffi::c_void, ptr, slice};
+
+use anyhow::{anyhow, Result};
+use bitflags::bitflags;
+use num_derive::{FromPrimitive, ToPrimitive};
+use serde::{Deserialize, Serialize};
+
+use super::address_set::AddressSet;
+
+#[repr(C)]
+struct VB {
+    _data: [u8; 0],
+}
+
+#[allow(non_camel_case_types)]
+type c_int = i32;
+#[allow(non_camel_case_types)]
+type c_uint = u32;
+
+#[repr(u32)]
+#[derive(FromPrimitive, ToPrimitive)]
+enum VBDataType {
+    S8 = 0,
+    U8 = 1,
+    S16 = 2,
+    U16 = 3,
+    S32 = 4,
+    F32 = 5,
+}
+
+#[repr(i32)]
+#[derive(FromPrimitive, ToPrimitive)]
+enum VBOption {
+    PseudoHalt = 0,
+}
+
+bitflags! {
+    #[repr(transparent)]
+    #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
+    pub struct VBKey: u16 {
+        const PWR = 0x0001;
+        const SGN = 0x0002;
+        const A   = 0x0004;
+        const B   = 0x0008;
+        const RT  = 0x0010;
+        const LT  = 0x0020;
+        const RU  = 0x0040;
+        const RR  = 0x0080;
+        const LR  = 0x0100;
+        const LL  = 0x0200;
+        const LD  = 0x0400;
+        const LU  = 0x0800;
+        const STA = 0x1000;
+        const SEL = 0x2000;
+        const RL  = 0x4000;
+        const RD  = 0x8000;
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+pub enum VBRegister {
+    Program(u32),
+    System(u32),
+    PC,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum VBWatchpointType {
+    Read,
+    Write,
+    Access,
+}
+
+type OnExecute =
+    extern "C" fn(sim: *mut VB, address: u32, code: *const u16, length: c_int) -> c_int;
+type OnFrame = extern "C" fn(sim: *mut VB) -> c_int;
+type OnRead = extern "C" fn(
+    sim: *mut VB,
+    address: u32,
+    type_: VBDataType,
+    value: *mut i32,
+    cycles: *mut u32,
+) -> c_int;
+type OnWrite = extern "C" fn(
+    sim: *mut VB,
+    address: u32,
+    type_: VBDataType,
+    value: *mut i32,
+    cycles: *mut u32,
+    cancel: *mut c_int,
+) -> c_int;
+
+#[link(name = "vb")]
+extern "C" {
+    #[link_name = "vbEmulate"]
+    fn vb_emulate(sim: *mut VB, cycles: *mut u32) -> c_int;
+    #[link_name = "vbEmulateEx"]
+    fn vb_emulate_ex(sims: *mut *mut VB, count: c_uint, cycles: *mut u32) -> c_int;
+    #[link_name = "vbGetCartRAM"]
+    fn vb_get_cart_ram(sim: *mut VB, size: *mut u32) -> *mut c_void;
+    #[link_name = "vbGetCartROM"]
+    fn vb_get_cart_rom(sim: *mut VB, size: *mut u32) -> *mut c_void;
+    #[link_name = "vbGetPixels"]
+    fn vb_get_pixels(
+        sim: *mut VB,
+        left: *mut c_void,
+        left_stride_x: c_int,
+        left_stride_y: c_int,
+        right: *mut c_void,
+        right_stride_x: c_int,
+        right_stride_y: c_int,
+    );
+    #[link_name = "vbGetProgramCounter"]
+    fn vb_get_program_counter(sim: *mut VB) -> u32;
+    #[link_name = "vbGetProgramRegister"]
+    fn vb_get_program_register(sim: *mut VB, index: c_uint) -> i32;
+    #[link_name = "vbGetSamples"]
+    fn vb_get_samples(
+        sim: *mut VB,
+        typ_: *mut VBDataType,
+        capacity: *mut c_uint,
+        position: *mut c_uint,
+    ) -> *mut c_void;
+    #[link_name = "vbGetSystemRegister"]
+    fn vb_get_system_register(sim: *mut VB, index: c_uint) -> i32;
+    #[link_name = "vbGetUserData"]
+    fn vb_get_user_data(sim: *mut VB) -> *mut c_void;
+    #[link_name = "vbInit"]
+    fn vb_init(sim: *mut VB) -> *mut VB;
+    #[link_name = "vbRead"]
+    fn vb_read(sim: *mut VB, address: u32, typ_: VBDataType) -> i32;
+    #[link_name = "vbReset"]
+    fn vb_reset(sim: *mut VB);
+    #[link_name = "vbSetCartRAM"]
+    fn vb_set_cart_ram(sim: *mut VB, sram: *mut c_void, size: u32) -> c_int;
+    #[link_name = "vbSetCartROM"]
+    fn vb_set_cart_rom(sim: *mut VB, rom: *mut c_void, size: u32) -> c_int;
+    #[link_name = "vbSetExecuteCallback"]
+    fn vb_set_execute_callback(sim: *mut VB, callback: Option<OnExecute>) -> Option<OnExecute>;
+    #[link_name = "vbSetFrameCallback"]
+    fn vb_set_frame_callback(sim: *mut VB, callback: Option<OnFrame>) -> Option<OnFrame>;
+    #[link_name = "vbSetKeys"]
+    fn vb_set_keys(sim: *mut VB, keys: u16) -> u16;
+    #[link_name = "vbSetOption"]
+    fn vb_set_option(sim: *mut VB, key: VBOption, value: c_int);
+    #[link_name = "vbSetPeer"]
+    fn vb_set_peer(sim: *mut VB, peer: *mut VB);
+    #[link_name = "vbSetProgramCounter"]
+    fn vb_set_program_counter(sim: *mut VB, value: u32) -> u32;
+    #[link_name = "vbSetProgramRegister"]
+    fn vb_set_program_register(sim: *mut VB, index: c_uint, value: i32) -> i32;
+    #[link_name = "vbSetReadCallback"]
+    fn vb_set_read_callback(sim: *mut VB, callback: Option<OnRead>) -> Option<OnRead>;
+    #[link_name = "vbSetSamples"]
+    fn vb_set_samples(
+        sim: *mut VB,
+        samples: *mut c_void,
+        typ_: VBDataType,
+        capacity: c_uint,
+    ) -> c_int;
+    #[link_name = "vbSetSystemRegister"]
+    fn vb_set_system_register(sim: *mut VB, index: c_uint, value: u32) -> u32;
+    #[link_name = "vbSetUserData"]
+    fn vb_set_user_data(sim: *mut VB, tag: *mut c_void);
+    #[link_name = "vbSetWriteCallback"]
+    fn vb_set_write_callback(sim: *mut VB, callback: Option<OnWrite>) -> Option<OnWrite>;
+    #[link_name = "vbSizeOf"]
+    fn vb_size_of() -> usize;
+    #[link_name = "vbWrite"]
+    fn vb_write(sim: *mut VB, address: u32, _type: VBDataType, value: i32) -> i32;
+}
+
+#[no_mangle]
+extern "C" fn on_frame(sim: *mut VB) -> c_int {
+    // SAFETY: the *mut VB owns its userdata.
+    // There is no way for the userdata to be null or otherwise invalid.
+    let data: &mut VBState = unsafe { &mut *vb_get_user_data(sim).cast() };
+    data.frame_seen = true;
+    1
+}
+
+#[no_mangle]
+extern "C" fn on_execute(sim: *mut VB, address: u32, _code: *const u16, _length: c_int) -> c_int {
+    // SAFETY: the *mut VB owns its userdata.
+    // There is no way for the userdata to be null or otherwise invalid.
+    let data: &mut VBState = unsafe { &mut *vb_get_user_data(sim).cast() };
+
+    let mut stopped = data.stop_reason.is_some();
+    if data.step_from.is_some_and(|s| s != address) {
+        data.step_from = None;
+        data.stop_reason = Some(StopReason::Stepped);
+        stopped = true;
+    }
+    if data.breakpoints.binary_search(&address).is_ok() {
+        data.stop_reason = Some(StopReason::Breakpoint);
+        stopped = true;
+    }
+
+    if stopped {
+        1
+    } else {
+        0
+    }
+}
+
+#[no_mangle]
+extern "C" fn on_read(
+    sim: *mut VB,
+    address: u32,
+    _type: VBDataType,
+    _value: *mut i32,
+    _cycles: *mut u32,
+) -> c_int {
+    // SAFETY: the *mut VB owns its userdata.
+    // There is no way for the userdata to be null or otherwise invalid.
+    let data: &mut VBState = unsafe { &mut *vb_get_user_data(sim).cast() };
+
+    if let Some(start) = data.read_watchpoints.start_of_range_containing(address) {
+        let watch = if data.write_watchpoints.contains(address) {
+            VBWatchpointType::Access
+        } else {
+            VBWatchpointType::Read
+        };
+        data.stop_reason = Some(StopReason::Watchpoint(watch, start));
+    }
+
+    // Don't stop here, the debugger expects us to break after the memory access.
+    // We'll stop in on_execute instead.
+    0
+}
+
+#[no_mangle]
+extern "C" fn on_write(
+    sim: *mut VB,
+    address: u32,
+    _type: VBDataType,
+    _value: *mut i32,
+    _cycles: *mut u32,
+    _cancel: *mut c_int,
+) -> c_int {
+    // SAFETY: the *mut VB owns its userdata.
+    // There is no way for the userdata to be null or otherwise invalid.
+    let data: &mut VBState = unsafe { &mut *vb_get_user_data(sim).cast() };
+
+    if let Some(start) = data.write_watchpoints.start_of_range_containing(address) {
+        let watch = if data.read_watchpoints.contains(address) {
+            VBWatchpointType::Access
+        } else {
+            VBWatchpointType::Write
+        };
+        data.stop_reason = Some(StopReason::Watchpoint(watch, start));
+    }
+
+    // Don't stop here, the debugger expects us to break after the memory access.
+    // We'll stop in on_execute instead.
+    0
+}
+
+const AUDIO_CAPACITY_SAMPLES: usize = 834 * 4;
+const AUDIO_CAPACITY_FLOATS: usize = AUDIO_CAPACITY_SAMPLES * 2;
+pub const EXPECTED_FRAME_SIZE: usize = 834 * 2;
+
+struct VBState {
+    frame_seen: bool,
+    stop_reason: Option<StopReason>,
+    step_from: Option<u32>,
+    breakpoints: Vec<u32>,
+    read_watchpoints: AddressSet,
+    write_watchpoints: AddressSet,
+}
+
+impl VBState {
+    fn needs_execute_callback(&self) -> bool {
+        self.step_from.is_some()
+            || !self.breakpoints.is_empty()
+            || !self.read_watchpoints.is_empty()
+            || !self.write_watchpoints.is_empty()
+    }
+}
+
+pub enum StopReason {
+    Breakpoint,
+    Watchpoint(VBWatchpointType, u32),
+    Stepped,
+}
+
+#[repr(transparent)]
+pub struct Sim {
+    sim: *mut VB,
+}
+
+impl Sim {
+    pub fn new() -> Self {
+        // init the VB instance itself
+        let size = unsafe { vb_size_of() };
+        // allocate a vec of u64 so that this memory is 8-byte aligned
+        let memory = vec![0u64; size.div_ceil(4)];
+        let sim: *mut VB = Box::into_raw(memory.into_boxed_slice()).cast();
+        unsafe { vb_init(sim) };
+        // pseudohalt is disabled due to breaking red alarm
+        unsafe { vb_set_option(sim, VBOption::PseudoHalt, 0) };
+        unsafe { vb_set_keys(sim, VBKey::SGN.bits()) };
+        unsafe { vb_reset(sim) };
+
+        // set up userdata
+        let state = VBState {
+            frame_seen: false,
+            stop_reason: None,
+            step_from: None,
+            breakpoints: vec![],
+            read_watchpoints: AddressSet::new(),
+            write_watchpoints: AddressSet::new(),
+        };
+        unsafe { vb_set_user_data(sim, Box::into_raw(Box::new(state)).cast()) };
+        unsafe { vb_set_frame_callback(sim, Some(on_frame)) };
+
+        // set up audio buffer
+        let audio_buffer = vec![0.0f32; AUDIO_CAPACITY_FLOATS];
+        let samples: *mut c_void = Box::into_raw(audio_buffer.into_boxed_slice()).cast();
+        unsafe { vb_set_samples(sim, samples, VBDataType::F32, AUDIO_CAPACITY_SAMPLES as u32) };
+
+        Sim { sim }
+    }
+
+    pub fn reset(&mut self) {
+        unsafe { vb_reset(self.sim) };
+    }
+
+    pub fn load_cart(&mut self, mut rom: Vec<u8>, mut sram: Vec<u8>) -> Result<()> {
+        self.unload_cart();
+
+        rom.shrink_to_fit();
+        sram.shrink_to_fit();
+
+        let size = rom.len() as u32;
+        let rom = Box::into_raw(rom.into_boxed_slice()).cast();
+        let status = unsafe { vb_set_cart_rom(self.sim, rom, size) };
+        if status != 0 {
+            let _: Vec<u8> =
+                unsafe { Vec::from_raw_parts(rom.cast(), size as usize, size as usize) };
+            return Err(anyhow!("Invalid ROM size of {} bytes", size));
+        }
+
+        let size = sram.len() as u32;
+        let sram = Box::into_raw(sram.into_boxed_slice()).cast();
+        let status = unsafe { vb_set_cart_ram(self.sim, sram, size) };
+        if status != 0 {
+            let _: Vec<u8> =
+                unsafe { Vec::from_raw_parts(sram.cast(), size as usize, size as usize) };
+            return Err(anyhow!("Invalid SRAM size of {} bytes", size));
+        }
+
+        Ok(())
+    }
+
+    fn unload_cart(&mut self) {
+        let mut size = 0;
+        let rom = unsafe { vb_get_cart_rom(self.sim, &mut size) };
+        unsafe { vb_set_cart_rom(self.sim, ptr::null_mut(), 0) };
+        if !rom.is_null() {
+            let _: Vec<u8> =
+                unsafe { Vec::from_raw_parts(rom.cast(), size as usize, size as usize) };
+        }
+
+        let sram = unsafe { vb_get_cart_ram(self.sim, &mut size) };
+        unsafe { vb_set_cart_ram(self.sim, ptr::null_mut(), 0) };
+        if !sram.is_null() {
+            let _: Vec<u8> =
+                unsafe { Vec::from_raw_parts(sram.cast(), size as usize, size as usize) };
+        }
+    }
+
+    pub fn read_sram(&mut self, buffer: &mut [u8]) {
+        let mut size = 0;
+        let sram = unsafe { vb_get_cart_ram(self.sim, &mut size) };
+        if sram.is_null() {
+            return;
+        }
+        let bytes = unsafe { slice::from_raw_parts(sram.cast(), size as usize) };
+        buffer.copy_from_slice(bytes);
+    }
+
+    pub fn link(&mut self, peer: &mut Sim) {
+        unsafe { vb_set_peer(self.sim, peer.sim) };
+    }
+
+    pub fn unlink(&mut self) {
+        unsafe { vb_set_peer(self.sim, ptr::null_mut()) };
+    }
+
+    pub fn emulate(&mut self) {
+        let mut cycles = 20_000_000;
+        unsafe { vb_emulate(self.sim, &mut cycles) };
+    }
+
+    pub fn emulate_many(sims: &mut [Sim]) {
+        let mut cycles = 20_000_000;
+        let count = sims.len() as c_uint;
+        let sims = sims.as_mut_ptr().cast();
+        unsafe { vb_emulate_ex(sims, count, &mut cycles) };
+    }
+
+    pub fn read_pixels(&mut self, buffers: &mut [u8]) -> bool {
+        let data = self.get_state();
+        if !data.frame_seen {
+            return false;
+        }
+        data.frame_seen = false;
+
+        // the buffer must be big enough for our data
+        assert!(buffers.len() >= 384 * 224 * 2);
+        unsafe {
+            vb_get_pixels(
+                self.sim,
+                buffers.as_mut_ptr().cast(),
+                2,
+                384 * 2,
+                buffers.as_mut_ptr().offset(1).cast(),
+                2,
+                384 * 2,
+            );
+        };
+        true
+    }
+
+    pub fn read_samples(&mut self, samples: &mut Vec<f32>, weight: f32) {
+        let mut position = 0;
+        let ptr =
+            unsafe { vb_get_samples(self.sim, ptr::null_mut(), ptr::null_mut(), &mut position) };
+        // SAFETY: position is an offset in a buffer of (f32, f32). so, position * 2 is an offset in a buffer of f32.
+        let read_samples: &[f32] =
+            unsafe { slice::from_raw_parts(ptr.cast(), position as usize * 2) };
+        samples.resize(read_samples.len(), 0.0);
+        for (index, sample) in read_samples.iter().enumerate() {
+            samples[index] += sample * weight;
+        }
+
+        unsafe {
+            vb_set_samples(
+                self.sim,
+                ptr,
+                VBDataType::F32,
+                AUDIO_CAPACITY_SAMPLES as u32,
+            )
+        };
+    }
+
+    pub fn set_keys(&mut self, keys: VBKey) {
+        unsafe { vb_set_keys(self.sim, keys.bits()) };
+    }
+
+    pub fn read_register(&mut self, register: VBRegister) -> u32 {
+        match register {
+            VBRegister::Program(index) => unsafe {
+                vb_get_program_register(self.sim, index) as u32
+            },
+            VBRegister::System(index) => unsafe { vb_get_system_register(self.sim, index) as u32 },
+            VBRegister::PC => unsafe { vb_get_program_counter(self.sim) },
+        }
+    }
+
+    pub fn write_register(&mut self, register: VBRegister, value: u32) {
+        match register {
+            VBRegister::Program(index) => unsafe {
+                vb_set_program_register(self.sim, index, value as i32);
+            },
+            VBRegister::System(index) => unsafe {
+                vb_set_system_register(self.sim, index, value);
+            },
+            VBRegister::PC => unsafe {
+                vb_set_program_counter(self.sim, value);
+            },
+        }
+    }
+
+    pub fn read_memory(&mut self, start: u32, length: usize, into: &mut Vec<u8>) {
+        let mut address = start;
+        for _ in 0..length {
+            let byte = unsafe { vb_read(self.sim, address, VBDataType::U8) };
+            into.push(byte as u8);
+            address = address.wrapping_add(1);
+        }
+    }
+
+    pub fn write_memory(&mut self, start: u32, buffer: &[u8]) {
+        let mut address = start;
+        for byte in buffer {
+            unsafe { vb_write(self.sim, address, VBDataType::U8, *byte as i32) };
+            address = address.wrapping_add(1);
+        }
+    }
+
+    pub fn add_breakpoint(&mut self, address: u32) {
+        let data = self.get_state();
+        if let Err(index) = data.breakpoints.binary_search(&address) {
+            data.breakpoints.insert(index, address);
+        }
+
+        unsafe {
+            vb_set_execute_callback(self.sim, Some(on_execute));
+        }
+    }
+
+    pub fn remove_breakpoint(&mut self, address: u32) {
+        let data = self.get_state();
+        if let Ok(index) = data.breakpoints.binary_search(&address) {
+            data.breakpoints.remove(index);
+            if !data.needs_execute_callback() {
+                unsafe { vb_set_execute_callback(self.sim, None) };
+            }
+        }
+    }
+
+    pub fn add_watchpoint(&mut self, address: u32, length: usize, watch: VBWatchpointType) {
+        match watch {
+            VBWatchpointType::Read => self.add_read_watchpoint(address, length),
+            VBWatchpointType::Write => self.add_write_watchpoint(address, length),
+            VBWatchpointType::Access => {
+                self.add_read_watchpoint(address, length);
+                self.add_write_watchpoint(address, length);
+            }
+        }
+    }
+
+    fn add_read_watchpoint(&mut self, address: u32, length: usize) {
+        let state = self.get_state();
+        state.read_watchpoints.add(address, length);
+        if !state.read_watchpoints.is_empty() {
+            unsafe { vb_set_read_callback(self.sim, Some(on_read)) };
+            unsafe { vb_set_execute_callback(self.sim, Some(on_execute)) };
+        }
+    }
+
+    fn add_write_watchpoint(&mut self, address: u32, length: usize) {
+        let state = self.get_state();
+        state.write_watchpoints.add(address, length);
+        if !state.write_watchpoints.is_empty() {
+            unsafe { vb_set_write_callback(self.sim, Some(on_write)) };
+            unsafe { vb_set_execute_callback(self.sim, Some(on_execute)) };
+        }
+    }
+
+    pub fn remove_watchpoint(&mut self, address: u32, length: usize, watch: VBWatchpointType) {
+        match watch {
+            VBWatchpointType::Read => self.remove_read_watchpoint(address, length),
+            VBWatchpointType::Write => self.remove_write_watchpoint(address, length),
+            VBWatchpointType::Access => {
+                self.remove_read_watchpoint(address, length);
+                self.remove_write_watchpoint(address, length);
+            }
+        }
+    }
+
+    fn remove_read_watchpoint(&mut self, address: u32, length: usize) {
+        let state = self.get_state();
+        state.read_watchpoints.remove(address, length);
+        let needs_execute = state.needs_execute_callback();
+        if state.read_watchpoints.is_empty() {
+            unsafe { vb_set_read_callback(self.sim, None) };
+            if !needs_execute {
+                unsafe { vb_set_execute_callback(self.sim, None) };
+            }
+        }
+    }
+
+    fn remove_write_watchpoint(&mut self, address: u32, length: usize) {
+        let state = self.get_state();
+        state.write_watchpoints.remove(address, length);
+        let needs_execute = state.needs_execute_callback();
+        if state.write_watchpoints.is_empty() {
+            unsafe { vb_set_write_callback(self.sim, None) };
+            if !needs_execute {
+                unsafe { vb_set_execute_callback(self.sim, None) };
+            }
+        }
+    }
+
+    pub fn step(&mut self) {
+        let current_pc = unsafe { vb_get_program_counter(self.sim) };
+        let data = self.get_state();
+        data.step_from = Some(current_pc);
+        unsafe {
+            vb_set_execute_callback(self.sim, Some(on_execute));
+        }
+    }
+
+    pub fn clear_debug_state(&mut self) {
+        let data = self.get_state();
+        data.step_from = None;
+        data.breakpoints.clear();
+        data.read_watchpoints.clear();
+        data.write_watchpoints.clear();
+        unsafe { vb_set_read_callback(self.sim, None) };
+        unsafe { vb_set_write_callback(self.sim, None) };
+        unsafe { vb_set_execute_callback(self.sim, None) };
+    }
+
+    pub fn stop_reason(&mut self) -> Option<StopReason> {
+        let data = self.get_state();
+        let reason = data.stop_reason.take();
+        if !data.needs_execute_callback() {
+            unsafe { vb_set_execute_callback(self.sim, None) };
+        }
+        reason
+    }
+
+    fn get_state(&mut self) -> &mut VBState {
+        // SAFETY: the *mut VB owns its userdata.
+        // There is no way for the userdata to be null or otherwise invalid.
+        unsafe { &mut *vb_get_user_data(self.sim).cast() }
+    }
+}
+
+impl Drop for Sim {
+    fn drop(&mut self) {
+        let ptr =
+            unsafe { vb_get_samples(self.sim, ptr::null_mut(), ptr::null_mut(), ptr::null_mut()) };
+        // SAFETY: the audio buffer originally came from a Vec<u32>
+        let floats: Vec<f32> = unsafe {
+            Vec::from_raw_parts(ptr.cast(), AUDIO_CAPACITY_FLOATS, AUDIO_CAPACITY_FLOATS)
+        };
+        drop(floats);
+
+        // SAFETY: the *mut VB owns its userdata.
+        // There is no way for the userdata to be null or otherwise invalid.
+        let ptr: *mut VBState = unsafe { vb_get_user_data(self.sim).cast() };
+        // SAFETY: we made this pointer ourselves, we can for sure free it
+        unsafe { drop(Box::from_raw(ptr)) };
+
+        // If we're linked to another sim, unlink from them.
+        unsafe { vb_set_peer(self.sim, ptr::null_mut()) };
+
+        let len = unsafe { vb_size_of() }.div_ceil(4);
+        // SAFETY: the sim's memory originally came from a Vec<u64>
+        let bytes: Vec<u64> = unsafe { Vec::from_raw_parts(self.sim.cast(), len, len) };
+        drop(bytes);
+    }
+}

src/game.wgsl

@@ -0,0 +1,79 @@
+// Vertex shader
+
+struct VertexOutput {
+    @builtin(position) clip_position: vec4<f32>,
+    @location(0) tex_coords: vec2<f32>,
+};
+
+@vertex
+fn vs_main(
+    @builtin(vertex_index) in_vertex_index: u32,
+) -> VertexOutput {
+    var out: VertexOutput;
+    var x: f32;
+    var y: f32;
+    switch in_vertex_index {
+        case 0u, 3u: {
+            x = -1.0;
+            y = 1.0;
+        }
+        case 1u: {
+            x = -1.0;
+            y = -1.0;
+        }
+        case 2u, 4u: {
+            x = 1.0;
+            y = -1.0;
+        }
+        default: {
+            x = 1.0;
+            y = 1.0;
+        }
+    }
+    out.clip_position = vec4<f32>(x, y, 0.0, 1.0);
+    out.tex_coords = vec2<f32>((x + 1.0) / 2.0, (1.0 - y) / 2.0);
+    return out;
+}
+
+// Fragment shader
+@group(0) @binding(0)
+var u_texture: texture_2d<f32>;
+@group(0) @binding(1)
+var u_sampler: sampler;
+
+struct Colors {
+    left: vec4<f32>,
+    right: vec4<f32>,
+};
+@group(0) @binding(2)
+var<uniform> colors: Colors;
+
+@fragment
+fn fs_lefteye(in: VertexOutput) -> @location(0) vec4<f32> {
+    let brt = textureSample(u_texture, u_sampler, in.tex_coords);
+    return colors.left * brt[0];
+}
+
+@fragment
+fn fs_righteye(in: VertexOutput) -> @location(0) vec4<f32> {
+    let brt = textureSample(u_texture, u_sampler, in.tex_coords);
+    return colors.left * brt[1];
+}
+
+@fragment
+fn fs_anaglyph(in: VertexOutput) -> @location(0) vec4<f32> {
+    let brt = textureSample(u_texture, u_sampler, in.tex_coords);
+    return colors.left * brt[0] + colors.right * brt[1];
+}
+
+@fragment
+fn fs_sidebyside(in: VertexOutput) -> @location(0) vec4<f32> {
+    var point = in.tex_coords;
+    point.x = (point.x * 2.0) % 1.0;
+    let brt = textureSample(u_texture, u_sampler, point);
+    if in.tex_coords.x < 0.5 {
+        return colors.left * brt[0];
+    } else {
+        return colors.left * brt[1];
+    };
+}

src/gdbserver.rs

@@ -0,0 +1,560 @@
+use anyhow::{bail, Result};
+use registers::REGISTERS;
+use request::{Request, RequestKind, RequestSource};
+use response::Response;
+use std::{
+    sync::{Arc, Mutex},
+    thread,
+};
+use tokio::{
+    io::{AsyncWriteExt as _, BufReader},
+    net::{TcpListener, TcpStream},
+    pin, select,
+    sync::{mpsc, oneshot},
+};
+use tracing::{debug, enabled, error, info, Level};
+
+use crate::emulator::{
+    DebugEvent, DebugStopReason, EmulatorClient, EmulatorCommand, SimId, VBWatchpointType,
+};
+
+mod registers;
+mod request;
+mod response;
+
+pub struct GdbServer {
+    sim_id: SimId,
+    client: EmulatorClient,
+    status: Arc<Mutex<GdbServerStatus>>,
+    killer: Option<oneshot::Sender<()>>,
+}
+
+impl GdbServer {
+    pub fn new(sim_id: SimId, client: EmulatorClient) -> Self {
+        Self {
+            sim_id,
+            client,
+            status: Arc::new(Mutex::new(GdbServerStatus::Stopped)),
+            killer: None,
+        }
+    }
+
+    pub fn status(&self) -> GdbServerStatus {
+        self.status.lock().unwrap().clone()
+    }
+
+    pub fn start(&mut self, port: u16) {
+        *self.status.lock().unwrap() = GdbServerStatus::Connecting;
+        let sim_id = self.sim_id;
+        let client = self.client.clone();
+        let status = self.status.clone();
+        let (tx, rx) = oneshot::channel();
+        self.killer = Some(tx);
+        thread::spawn(move || {
+            tokio::runtime::Builder::new_current_thread()
+                .enable_all()
+                .build()
+                .unwrap()
+                .block_on(async move {
+                    select! {
+                        _ = run_server(sim_id, client.clone(), port, &status) => {}
+                        _ = rx => {
+                            client.send_command(EmulatorCommand::StopDebugging(sim_id));
+                            *status.lock().unwrap() = GdbServerStatus::Stopped;
+                        }
+                    }
+                })
+        });
+    }
+
+    pub fn stop(&mut self) {
+        if let Some(killer) = self.killer.take() {
+            let _ = killer.send(());
+        }
+    }
+}
+
+impl Drop for GdbServer {
+    fn drop(&mut self) {
+        self.stop();
+    }
+}
+
+async fn run_server(
+    sim_id: SimId,
+    client: EmulatorClient,
+    port: u16,
+    status: &Mutex<GdbServerStatus>,
+) {
+    let (debug_sink, mut debug_source) = mpsc::unbounded_channel();
+    client.send_command(EmulatorCommand::StartDebugging(sim_id, debug_sink));
+
+    info!("Connecting to debugger on port {port}...");
+    let connect_future = try_connect(port, status);
+    pin!(connect_future);
+
+    let stream = loop {
+        select! {
+            stream = &mut connect_future => {
+                if let Some(stream) = stream {
+                    break stream;
+                } else {
+                    return;
+                }
+            }
+            event = debug_source.recv() => {
+                if event.is_none() {
+                    // The sim has stopped (or was never started)
+                    *status.lock().unwrap() = GdbServerStatus::Stopped;
+                    return;
+                }
+            }
+        }
+    };
+    info!("Connected!");
+    let mut connection = GdbConnection::new(sim_id, client);
+    match connection.run(stream, debug_source).await {
+        Ok(()) => {
+            info!("Finished debugging.");
+            *status.lock().unwrap() = GdbServerStatus::Stopped;
+        }
+        Err(error) => {
+            error!(%error, "Error from debugger.");
+            *status.lock().unwrap() = GdbServerStatus::Error(error.to_string());
+        }
+    }
+}
+
+async fn try_connect(port: u16, status: &Mutex<GdbServerStatus>) -> Option<TcpStream> {
+    *status.lock().unwrap() = GdbServerStatus::Connecting;
+    let listener = match TcpListener::bind(("127.0.0.1", port)).await {
+        Ok(l) => l,
+        Err(err) => {
+            error!(%err, "Could not open port.");
+            *status.lock().unwrap() = GdbServerStatus::Error(err.to_string());
+            return None;
+        }
+    };
+    match listener.accept().await {
+        Ok((stream, _)) => {
+            *status.lock().unwrap() = GdbServerStatus::Running;
+            Some(stream)
+        }
+        Err(err) => {
+            error!(%err, "Could not connect to debugger.");
+            *status.lock().unwrap() = GdbServerStatus::Error(err.to_string());
+            None
+        }
+    }
+}
+
+#[derive(Clone)]
+pub enum GdbServerStatus {
+    Stopped,
+    Connecting,
+    Running,
+    Error(String),
+}
+
+impl GdbServerStatus {
+    pub fn running(&self) -> bool {
+        matches!(self, Self::Connecting | Self::Running)
+    }
+}
+
+struct GdbConnection {
+    sim_id: SimId,
+    client: EmulatorClient,
+    ack_messages: bool,
+    stop_reason: Option<DebugStopReason>,
+    response_buf: Option<Vec<u8>>,
+    memory_buf: Option<Vec<u8>>,
+}
+
+impl GdbConnection {
+    fn new(sim_id: SimId, client: EmulatorClient) -> Self {
+        Self {
+            sim_id,
+            client,
+            ack_messages: true,
+            stop_reason: None,
+            response_buf: None,
+            memory_buf: None,
+        }
+    }
+    async fn run(
+        &mut self,
+        stream: TcpStream,
+        mut debug_source: mpsc::UnboundedReceiver<DebugEvent>,
+    ) -> Result<()> {
+        let (rx, mut tx) = stream.into_split();
+        let mut request_source = RequestSource::new(BufReader::new(rx));
+        loop {
+            let response = select! {
+                maybe_event = debug_source.recv() => {
+                    let Some(event) = maybe_event else {
+                        // debugger has stopped running
+                        break;
+                    };
+                    self.handle_event(event)
+                }
+                maybe_request = request_source.recv() => {
+                    let req = maybe_request?;
+                    self.handle_request(req)?
+                }
+            };
+            if let Some(res) = response {
+                let buffer = res.finish();
+                if enabled!(Level::DEBUG) {
+                    match std::str::from_utf8(&buffer) {
+                        Ok(text) => debug!("response: {text}"),
+                        Err(_) => debug!("response: {buffer:02x?}"),
+                    }
+                }
+                tx.write_all(&buffer).await?;
+                self.response_buf = Some(buffer);
+                tx.flush().await?;
+            }
+        }
+        Ok(())
+    }
+
+    fn handle_event(&mut self, event: DebugEvent) -> Option<Response> {
+        let res = match event {
+            DebugEvent::Stopped(reason) => {
+                if self.stop_reason.is_some_and(|r| r == reason) {
+                    return None;
+                }
+                self.stop_reason = Some(reason);
+                self.response()
+                    .write_str(&debug_stop_reason_string(self.stop_reason))
+            }
+        };
+        Some(res)
+    }
+
+    fn handle_request(&mut self, mut req: Request<'_>) -> Result<Option<Response>> {
+        debug!("received {:02x?}", req);
+
+        if req.kind == RequestKind::Signal {
+            self.client
+                .send_command(EmulatorCommand::DebugInterrupt(self.sim_id));
+            return Ok(None); // we'll send a message when the emulator reports it has stopped
+        }
+
+        let res = if req.match_str("QStartNoAckMode") {
+            let res = self.response().write_str("OK");
+            self.ack_messages = false;
+            res
+        } else if req.match_str("qSupported:") {
+            self.response()
+                .write_str("multiprocess+;swbreak+;vContSupported+;PacketSize=10000;SupportedWatchpointTypes=x86_64,aarch64-bas,aarch64-mask")
+        } else if req
+            .match_some_str([
+                "QThreadSuffixSupported",
+                "QListThreadsInStopReply",
+                "QEnableErrorStrings",
+            ])
+            .is_some()
+        {
+            self.response().write_str("OK")
+        } else if req.match_str("qHostInfo") {
+            self.response().write_str(&format!(
+                "triple:{};endian:little;ptrsize:4;",
+                hex::encode("v810-unknown-vb")
+            ))
+        } else if req.match_str("qProcessInfo") {
+            self.response().write_str(&format!(
+                "pid:1;triple:{};endian:little;ptrsize:4;",
+                hex::encode("v810-unknown-vb")
+            ))
+        } else if req.match_str("qRegisterInfo") {
+            let mut get_reg_info = || {
+                let register = req.match_hex::<usize>()?;
+                REGISTERS.get(register)
+            };
+            if let Some(reg_info) = get_reg_info() {
+                self.response().write_str(&reg_info.to_description())
+            } else {
+                self.response()
+            }
+        } else if req.match_str("vCont?") {
+            self.response().write_str("vCont;c;s;")
+        } else if req.match_str("qC") {
+            // The v810 has no threads, so report that the "current thread" is 1.
+            self.response().write_str("QCp1.t1")
+        } else if req.match_str("qfThreadInfo") {
+            self.response().write_str("mp1.t1")
+        } else if req.match_str("qsThreadInfo") {
+            self.response().write_str("l")
+        } else if req.match_str("k") {
+            bail!("debug process was killed");
+        } else if req.match_str("?") {
+            self.response()
+                .write_str(&debug_stop_reason_string(self.stop_reason))
+        } else if req.match_some_str(["c", "vCont;c:"]).is_some() {
+            self.client
+                .send_command(EmulatorCommand::DebugContinue(self.sim_id));
+            self.stop_reason = None;
+            // Don't send a response until we hit a breakpoint or get interrupted
+            return Ok(None);
+        } else if req.match_some_str(["s", "vCont;s:"]).is_some() {
+            self.client
+                .send_command(EmulatorCommand::DebugStep(self.sim_id));
+            self.stop_reason = None;
+            // Don't send a response until we hit a breakpoint or get interrupted
+            return Ok(None);
+        } else if req.match_str("p") {
+            let mut read_register = || {
+                let register_index = req.match_hex::<usize>()?;
+                let register = REGISTERS.get(register_index)?.to_vb_register();
+                let (tx, rx) = ::oneshot::channel();
+                self.client
+                    .send_command(EmulatorCommand::ReadRegister(self.sim_id, register, tx));
+                rx.recv().ok()
+            };
+            if let Some(value) = read_register() {
+                self.response().write_hex(value)
+            } else {
+                self.response()
+            }
+        } else if req.match_str("P") {
+            let mut write_register = || {
+                let register_index = req.match_hex::<usize>()?;
+                let register = REGISTERS.get(register_index)?.to_vb_register();
+                if !req.match_str("=") {
+                    return None;
+                }
+                let value = {
+                    let mut buffer = [0; 4];
+                    if !req.match_hex_bytes(&mut buffer) {
+                        return None;
+                    }
+                    u32::from_le_bytes(buffer)
+                };
+                self.client.send_command(EmulatorCommand::WriteRegister(
+                    self.sim_id,
+                    register,
+                    value,
+                ));
+                Some(())
+            };
+            if let Some(()) = write_register() {
+                self.response().write_str("OK")
+            } else {
+                self.response()
+            }
+        } else if let Some(op) = req.match_some_str(["m", "x"]) {
+            let mut read_memory = || {
+                let (start, length) = parse_memory_range(&mut req)?;
+                let mut buf = self.memory_buf.take().unwrap_or_default();
+                buf.clear();
+                if length == 0 {
+                    return Some(buf);
+                }
+                let (tx, rx) = ::oneshot::channel();
+                self.client.send_command(EmulatorCommand::ReadMemory(
+                    self.sim_id,
+                    start,
+                    length,
+                    buf,
+                    tx,
+                ));
+                rx.recv().ok()
+            };
+            if let Some(memory) = read_memory() {
+                let mut res = self.response();
+                if memory.is_empty() {
+                    res = res.write_str("OK");
+                } else if op == "m" {
+                    // send the hex-encoded byte stream
+                    for byte in &memory {
+                        res = res.write_hex(*byte);
+                    }
+                } else {
+                    // send the raw byte stream
+                    for byte in &memory {
+                        res = res.write_byte(*byte);
+                    }
+                }
+                self.memory_buf = Some(memory);
+                res
+            } else {
+                self.response()
+            }
+        } else if let Some(op) = req.match_some_str(["M", "X"]) {
+            let mut write_memory = || {
+                let (start, length) = parse_memory_range(&mut req)?;
+                if length == 0 {
+                    return Some(());
+                }
+                if !req.match_str(":") {
+                    return None;
+                }
+                let mut buf = self.memory_buf.take().unwrap_or_default();
+                buf.resize(length, 0);
+                let successful_read = if op == "M" {
+                    req.match_hex_bytes(&mut buf)
+                } else {
+                    req.match_bytes(&mut buf)
+                };
+                if !successful_read {
+                    self.memory_buf = Some(buf);
+                    return None;
+                }
+                let (tx, rx) = ::oneshot::channel();
+                self.client
+                    .send_command(EmulatorCommand::WriteMemory(self.sim_id, start, buf, tx));
+                let buf = rx.recv().ok()?;
+                self.memory_buf = Some(buf);
+                Some(())
+            };
+            if write_memory().is_some() {
+                self.response().write_str("OK")
+            } else {
+                self.response()
+            }
+        } else if req.match_str("Z") {
+            let mut parse_request = || {
+                let type_ = req.match_hex::<u8>()?;
+                if !req.match_str(",") {
+                    return None;
+                }
+                let address = req.match_hex()?;
+                if type_ == 0 || type_ == 1 {
+                    return Some(EmulatorCommand::AddBreakpoint(self.sim_id, address));
+                }
+                if !req.match_str(",") {
+                    return None;
+                }
+                let length = req.match_hex()?;
+                let watch = match type_ {
+                    2 => VBWatchpointType::Write,
+                    3 => VBWatchpointType::Read,
+                    4 => VBWatchpointType::Access,
+                    _ => return None,
+                };
+                Some(EmulatorCommand::AddWatchpoint(
+                    self.sim_id,
+                    address,
+                    length,
+                    watch,
+                ))
+            };
+            if let Some(command) = parse_request() {
+                self.client.send_command(command);
+                self.response().write_str("OK")
+            } else {
+                self.response()
+            }
+        } else if req.match_str("z") {
+            let mut parse_request = || {
+                let type_ = req.match_hex::<u8>()?;
+                if !req.match_str(",") {
+                    return None;
+                }
+                let address = req.match_hex()?;
+                if type_ == 0 || type_ == 1 {
+                    return Some(EmulatorCommand::RemoveBreakpoint(self.sim_id, address));
+                }
+                if !req.match_str(",") {
+                    return None;
+                }
+                let length = req.match_hex()?;
+                let watch = match type_ {
+                    2 => VBWatchpointType::Write,
+                    3 => VBWatchpointType::Read,
+                    4 => VBWatchpointType::Access,
+                    _ => return None,
+                };
+                Some(EmulatorCommand::RemoveWatchpoint(
+                    self.sim_id,
+                    address,
+                    length,
+                    watch,
+                ))
+            };
+            if let Some(command) = parse_request() {
+                self.client.send_command(command);
+                self.response().write_str("OK")
+            } else {
+                self.response()
+            }
+        } else {
+            // unrecognized command
+            self.response()
+        };
+        Ok(Some(res))
+    }
+
+    fn response(&mut self) -> Response {
+        Response::new(
+            self.response_buf.take().unwrap_or_default(),
+            self.ack_messages,
+        )
+    }
+}
+
+impl Drop for GdbConnection {
+    fn drop(&mut self) {
+        self.client
+            .send_command(EmulatorCommand::StopDebugging(self.sim_id));
+    }
+}
+
+// parse a memory range into a start and a length.
+fn parse_memory_range(req: &mut Request<'_>) -> Option<(u32, usize)> {
+    let start = req.match_hex::<u64>()?;
+    if !req.match_str(",") {
+        return None;
+    };
+    let length = req.match_hex::<usize>()?;
+    let Ok(start) = u32::try_from(start) else {
+        // The v810 has a 32-bit address space.
+        // Addresses wrap within that space, but we don't need to implement that for 64-bit addresses.
+        // Just refuse to return any info for addresses above 0xffffffff.
+        return Some((0, 0));
+    };
+    let length = length.min((u32::MAX - start) as usize + 1);
+    Some((start, length))
+}
+
+fn debug_stop_reason_string(reason: Option<DebugStopReason>) -> String {
+    let mut result = String::new();
+    result += if reason.is_some_and(|r| r != DebugStopReason::Paused) {
+        "T05;"
+    } else {
+        "T00;"
+    };
+    if let Some(DebugStopReason::Breakpoint) = reason {
+        result += "swbreak;";
+    }
+    if let Some(DebugStopReason::Watchpoint(watch, address)) = reason {
+        result += match watch {
+            VBWatchpointType::Write => "watch:",
+            VBWatchpointType::Read => "rwatch:",
+            VBWatchpointType::Access => "awatch:",
+        };
+        result += &format!("{address:08x};");
+    }
+
+    result += "thread:p1.t1;threads:p1.t1;";
+
+    if let Some(reason) = reason {
+        result += "reason:";
+        result += match reason {
+            DebugStopReason::Trace => "trace;",
+            DebugStopReason::Breakpoint => "breakpoint;",
+            DebugStopReason::Watchpoint(_, _) => "watchpoint;",
+            DebugStopReason::Paused => "trap;",
+        };
+    }
+
+    if let Some(DebugStopReason::Watchpoint(_, address)) = reason {
+        result += "description:";
+        result += &hex::encode(address.to_string());
+        result += ";";
+    }
+
+    result
+}

src/gdbserver/registers.rs

@@ -0,0 +1,130 @@
+use crate::emulator::VBRegister;
+
+pub struct RegisterInfo {
+    dwarf: u32,
+    name: &'static str,
+    set: &'static str,
+    alt_name: Option<&'static str>,
+    generic: Option<&'static str>,
+}
+
+impl RegisterInfo {
+    pub fn to_description(&self) -> String {
+        let mut string = format!("name:{}", self.name);
+        if let Some(alt) = self.alt_name {
+            string.push_str(&format!(";alt-name:{}", alt));
+        }
+        string.push_str(&format!(
+            ";bitsize:32;offset:{};encoding:uint;format:hex;set:{};dwarf:{}",
+            self.dwarf * 4,
+            self.set,
+            self.dwarf
+        ));
+        if let Some(generic) = self.generic {
+            string.push_str(&format!(";generic:{}", generic));
+        }
+        string
+    }
+
+    pub fn to_vb_register(&self) -> VBRegister {
+        match self.dwarf {
+            0..32 => VBRegister::Program(self.dwarf),
+            32..40 => VBRegister::System(self.dwarf - 32),
+            40..42 => VBRegister::System(self.dwarf - 16),
+            42..45 => VBRegister::System(self.dwarf - 13),
+            45 => VBRegister::PC,
+            other => panic!("unexpected DWARF register {other}"),
+        }
+    }
+}
+
+macro_rules! register {
+    ($set:expr, $dwarf:expr, $name:expr) => {
+        RegisterInfo {
+            dwarf: $dwarf,
+            name: $name,
+            set: $set,
+            alt_name: None,
+            generic: None,
+        }
+    };
+    ($set:expr, $dwarf:expr, $name:expr, alt: $alt:expr) => {
+        RegisterInfo {
+            dwarf: $dwarf,
+            name: $name,
+            set: $set,
+            alt_name: Some($alt),
+            generic: None,
+        }
+    };
+    ($set:expr, $dwarf:expr, $name:expr, generic: $generic:expr) => {
+        RegisterInfo {
+            dwarf: $dwarf,
+            name: $name,
+            set: $set,
+            alt_name: None,
+            generic: Some($generic),
+        }
+    };
+    ($set:expr, $dwarf:expr, $name:expr, alt: $alt:expr, generic: $generic:expr) => {
+        RegisterInfo {
+            dwarf: $dwarf,
+            name: $name,
+            set: $set,
+            alt_name: Some($alt),
+            generic: Some($generic),
+        }
+    };
+}
+
+const GENERAL: &str = "General Purpose Registers";
+const SPECIAL: &str = "Special Registers";
+
+pub const REGISTERS: [RegisterInfo; 46] = [
+    register!(GENERAL, 0, "r0"),
+    register!(GENERAL, 1, "r1"),
+    register!(GENERAL, 2, "fp", alt: "r2", generic: "fp"),
+    register!(GENERAL, 3, "sp", alt: "r3", generic: "sp"),
+    register!(GENERAL, 4, "gp", alt: "r4"),
+    register!(GENERAL, 5, "tp", alt: "r5"),
+    register!(GENERAL, 6, "r6", generic: "arg1"),
+    register!(GENERAL, 7, "r7", generic: "arg2"),
+    register!(GENERAL, 8, "r8", generic: "arg3"),
+    register!(GENERAL, 9, "r9", generic: "arg4"),
+    register!(GENERAL, 10, "r10"),
+    register!(GENERAL, 11, "r11"),
+    register!(GENERAL, 12, "r12"),
+    register!(GENERAL, 13, "r13"),
+    register!(GENERAL, 14, "r14"),
+    register!(GENERAL, 15, "r15"),
+    register!(GENERAL, 16, "r16"),
+    register!(GENERAL, 17, "r17"),
+    register!(GENERAL, 18, "r18"),
+    register!(GENERAL, 19, "r19"),
+    register!(GENERAL, 20, "r20"),
+    register!(GENERAL, 21, "r21"),
+    register!(GENERAL, 22, "r22"),
+    register!(GENERAL, 23, "r23"),
+    register!(GENERAL, 24, "r24"),
+    register!(GENERAL, 25, "r25"),
+    register!(GENERAL, 26, "r26"),
+    register!(GENERAL, 27, "r27"),
+    register!(GENERAL, 28, "r28"),
+    register!(GENERAL, 29, "r29"),
+    register!(GENERAL, 30, "r30"),
+    register!(GENERAL, 31, "lp", alt: "r31", generic: "ra"),
+    register!(SPECIAL, 32, "eipc", alt: "sr0"),
+    register!(SPECIAL, 33, "eipsw", alt: "sr1"),
+    register!(SPECIAL, 34, "fepc", alt: "sr2"),
+    register!(SPECIAL, 35, "fepsw", alt: "sr3"),
+    register!(SPECIAL, 36, "ecr", alt: "sr4"),
+    register!(SPECIAL, 37, "psw", alt: "sr5", generic: "flags"),
+    register!(SPECIAL, 38, "pir", alt: "sr6"),
+    register!(SPECIAL, 39, "tkcw", alt: "sr7"),
+    register!(SPECIAL, 40, "chcw", alt: "sr24"),
+    register!(SPECIAL, 41, "adtre", alt: "sr25"),
+    register!(SPECIAL, 42, "sr29"),
+    register!(SPECIAL, 43, "sr30"),
+    register!(SPECIAL, 44, "sr31"),
+    register!(SPECIAL, 45, "pc", generic: "pc"),
+];

src/gdbserver/request.rs

@@ -0,0 +1,202 @@
+use anyhow::{bail, Result};
+use atoi::FromRadix16;
+use tokio::io::{AsyncRead, AsyncReadExt as _};
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum RequestKind {
+    Signal,
+    Command,
+}
+impl RequestKind {
+    fn name(self) -> &'static str {
+        match self {
+            Self::Signal => "Signal",
+            Self::Command => "Command",
+        }
+    }
+}
+
+pub struct Request<'a> {
+    pub kind: RequestKind,
+    buffer: &'a [u8],
+}
+
+impl std::fmt::Debug for Request<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let mut ds = f.debug_tuple(self.kind.name());
+        match self.kind {
+            RequestKind::Signal => ds.field(&self.buffer),
+            RequestKind::Command => match std::str::from_utf8(self.buffer) {
+                Ok(str) => ds.field(&str),
+                Err(_) => ds.field(&self.buffer),
+            },
+        };
+        ds.finish()
+    }
+}
+
+impl Request<'_> {
+    pub fn match_str(&mut self, prefix: &str) -> bool {
+        if let Some(new_buffer) = self.buffer.strip_prefix(prefix.as_bytes()) {
+            self.buffer = new_buffer;
+            return true;
+        }
+        false
+    }
+
+    pub fn match_some_str<'a, I: IntoIterator<Item = &'a str>>(
+        &mut self,
+        prefixes: I,
+    ) -> Option<&'a str> {
+        prefixes.into_iter().find(|&prefix| self.match_str(prefix))
+    }
+
+    pub fn match_hex<I: FromRadix16>(&mut self) -> Option<I> {
+        match I::from_radix_16(self.buffer) {
+            (_, 0) => None,
+            (val, used) => {
+                self.buffer = self.buffer.split_at(used).1;
+                Some(val)
+            }
+        }
+    }
+
+    pub fn match_hex_bytes(&mut self, buffer: &mut [u8]) -> bool {
+        if self.buffer.len() < buffer.len() * 2 {
+            return false;
+        }
+        for (i, item) in buffer.iter_mut().enumerate() {
+            match u8::from_radix_16(&self.buffer[(i * 2)..(i * 2) + 2]) {
+                (byte, 2) => *item = byte,
+                _ => return false,
+            };
+        }
+        self.buffer = self.buffer.split_at(buffer.len()).1;
+        true
+    }
+
+    pub fn match_bytes(&mut self, buffer: &mut [u8]) -> bool {
+        if self.buffer.len() < buffer.len() {
+            return false;
+        }
+        buffer.copy_from_slice(&self.buffer[0..buffer.len()]);
+        self.buffer = self.buffer.split_at(buffer.len()).1;
+        true
+    }
+}
+
+pub struct RequestSource<R> {
+    reader: R,
+    buffer: Vec<u8>,
+    state: RequestReadState,
+}
+
+impl<R: AsyncRead + Unpin> RequestSource<R> {
+    pub fn new(reader: R) -> Self {
+        Self {
+            reader,
+            buffer: vec![],
+            state: RequestReadState::Header,
+        }
+    }
+
+    pub async fn recv(&mut self) -> Result<Request<'_>> {
+        let mut char = self.reader.read_u8().await?;
+        if matches!(self.state, RequestReadState::Start) {
+            self.buffer.clear();
+            self.state = RequestReadState::Header;
+        }
+        if matches!(self.state, RequestReadState::Header) {
+            // Just ignore positive acks
+            while char == b'+' {
+                char = self.reader.read_u8().await?;
+            }
+            if char == b'-' {
+                bail!("no support for negative acks");
+            }
+            if char == 0x03 {
+                // This is how the client "cancels an in-flight request"
+                self.buffer.push(char);
+                self.state = RequestReadState::Start;
+                return Ok(Request {
+                    kind: RequestKind::Signal,
+                    buffer: &self.buffer,
+                });
+            }
+            if char != b'$' {
+                // Messages are supposed to start with a dollar sign
+                bail!("malformed message");
+            }
+            self.state = RequestReadState::Body {
+                checksum: 0,
+                escaping: false,
+            };
+            char = self.reader.read_u8().await?;
+        }
+        while let RequestReadState::Body { checksum, escaping } = &mut self.state {
+            if char == b'#' && !*escaping {
+                self.state = RequestReadState::Checksum {
+                    expected: *checksum,
+                    actual: 0,
+                    digits: 0,
+                };
+                char = self.reader.read_u8().await?;
+                break;
+            }
+            *checksum = checksum.wrapping_add(char);
+
+            if *escaping {
+                // escaped character
+                self.buffer.push(char ^ 0x20);
+                *escaping = false;
+            } else if char == b'}' {
+                // next character will be escaped
+                *escaping = true;
+            } else {
+                self.buffer.push(char);
+            }
+            char = self.reader.read_u8().await?;
+        }
+        while let RequestReadState::Checksum {
+            expected,
+            actual,
+            digits,
+        } = &mut self.state
+        {
+            let digit = match char {
+                b'0'..=b'9' => char - b'0',
+                b'a'..=b'f' => char - b'a' + 10,
+                b'A'..=b'F' => char - b'A' + 10,
+                _ => bail!("invalid checksum"),
+            };
+            *actual = (*actual << 4) + digit;
+            *digits += 1;
+            if *digits == 2 {
+                if *expected != *actual {
+                    bail!("mismatched checksum");
+                }
+                self.state = RequestReadState::Start;
+                return Ok(Request {
+                    kind: RequestKind::Command,
+                    buffer: &self.buffer,
+                });
+            }
+            char = self.reader.read_u8().await?;
+        }
+        unreachable!();
+    }
+}
+
+enum RequestReadState {
+    Start,
+    Header,
+    Body {
+        checksum: u8,
+        escaping: bool,
+    },
+    Checksum {
+        expected: u8,
+        actual: u8,
+        digits: u8,
+    },
+}

src/gdbserver/response.rs

@@ -0,0 +1,63 @@
+use num_traits::ToBytes;
+
+pub struct Response {
+    buffer: Vec<u8>,
+    checksum: u8,
+}
+
+impl Response {
+    pub fn new(mut buffer: Vec<u8>, ack: bool) -> Self {
+        buffer.clear();
+        if ack {
+            buffer.push(b'+');
+        }
+        buffer.push(b'$');
+        Self {
+            buffer,
+            checksum: 0,
+        }
+    }
+
+    pub fn write_str(self, str: &str) -> Self {
+        let mut me = self;
+        for byte in str.as_bytes() {
+            me = me.write_byte(*byte);
+        }
+        me
+    }
+
+    pub fn write_byte(mut self, byte: u8) -> Self {
+        if byte == b'}' || byte == b'#' || byte == b'$' || byte == b'*' {
+            self.buffer.push(b'}');
+            self.checksum = self.checksum.wrapping_add(b'}');
+            let escaped = byte ^ 0x20;
+            self.buffer.push(escaped);
+            self.checksum = self.checksum.wrapping_add(escaped);
+        } else {
+            self.buffer.push(byte);
+            self.checksum = self.checksum.wrapping_add(byte);
+        }
+        self
+    }
+
+    pub fn write_hex<T: ToBytes>(mut self, value: T) -> Self {
+        for byte in value.to_le_bytes().as_ref() {
+            for digit in [(byte >> 4), (byte & 0xf)] {
+                let char = if digit > 9 {
+                    b'a' + digit - 10
+                } else {
+                    b'0' + digit
+                };
+                self.buffer.push(char);
+                self.checksum = self.checksum.wrapping_add(char);
+            }
+        }
+        self
+    }
+
+    pub fn finish(mut self) -> Vec<u8> {
+        let checksum = self.checksum;
+        self.buffer.push(b'#');
+        self.write_hex(checksum).buffer
+    }
+}

src/graphics.rs

@@ -0,0 +1,143 @@
+use std::{
+    sync::{
+        atomic::{AtomicU64, Ordering},
+        mpsc, Arc, Mutex, MutexGuard,
+    },
+    thread,
+};
+
+use anyhow::{bail, Result};
+use itertools::Itertools as _;
+use wgpu::{
+    Device, Extent3d, ImageCopyTexture, ImageDataLayout, Origin3d, Queue, Texture,
+    TextureDescriptor, TextureFormat, TextureUsages, TextureView, TextureViewDescriptor,
+};
+
+#[derive(Debug)]
+pub struct TextureSink {
+    buffers: Arc<BufferPool>,
+    sink: mpsc::Sender<u64>,
+}
+
+impl TextureSink {
+    pub fn new(device: &Device, queue: Arc<Queue>) -> (Self, TextureView) {
+        let texture = Self::create_texture(device);
+        let view = texture.create_view(&TextureViewDescriptor::default());
+        let buffers = Arc::new(BufferPool::new());
+        let (sink, source) = mpsc::channel();
+        let bufs = buffers.clone();
+        thread::spawn(move || {
+            let mut local_buf = vec![0; 384 * 224 * 2];
+            while let Ok(id) = source.recv() {
+                {
+                    let Some(bytes) = bufs.read(id) else {
+                        continue;
+                    };
+                    local_buf.copy_from_slice(bytes.as_slice());
+                }
+                Self::write_texture(&queue, &texture, local_buf.as_slice());
+            }
+        });
+        let sink = Self { buffers, sink };
+        (sink, view)
+    }
+
+    pub fn queue_render(&mut self, bytes: &[u8]) -> Result<()> {
+        let id = {
+            let (mut buf, id) = self.buffers.write()?;
+            buf.copy_from_slice(bytes);
+            id
+        };
+        self.sink.send(id)?;
+        Ok(())
+    }
+
+    fn create_texture(device: &Device) -> Texture {
+        let desc = TextureDescriptor {
+            label: Some("eyes"),
+            size: Extent3d {
+                width: 384,
+                height: 224,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: TextureFormat::Rg8Unorm,
+            usage: TextureUsages::COPY_SRC
+                | TextureUsages::COPY_DST
+                | TextureUsages::TEXTURE_BINDING,
+            view_formats: &[TextureFormat::Rg8Unorm],
+        };
+        device.create_texture(&desc)
+    }
+
+    fn write_texture(queue: &Queue, texture: &Texture, bytes: &[u8]) {
+        let texture = ImageCopyTexture {
+            texture,
+            mip_level: 0,
+            origin: Origin3d::ZERO,
+            aspect: wgpu::TextureAspect::All,
+        };
+        let size = Extent3d {
+            width: 384,
+            height: 224,
+            depth_or_array_layers: 1,
+        };
+        let data_layout = ImageDataLayout {
+            offset: 0,
+            bytes_per_row: Some(384 * 2),
+            rows_per_image: Some(224),
+        };
+        queue.write_texture(texture, bytes, data_layout, size);
+    }
+}
+
+#[derive(Debug)]
+struct BufferPool {
+    buffers: [Buffer; 3],
+}
+impl BufferPool {
+    fn new() -> Self {
+        Self {
+            buffers: std::array::from_fn(|i| Buffer::new(i as u64)),
+        }
+    }
+
+    fn read(&self, id: u64) -> Option<MutexGuard<'_, Vec<u8>>> {
+        let buf = self
+            .buffers
+            .iter()
+            .find(|buf| buf.id.load(Ordering::Acquire) == id)?;
+        buf.data.lock().ok()
+    }
+
+    fn write(&self) -> Result<(MutexGuard<'_, Vec<u8>>, u64)> {
+        let (min, max) = self
+            .buffers
+            .iter()
+            .minmax_by_key(|buf| buf.id.load(Ordering::Acquire))
+            .into_option()
+            .unwrap();
+        let Ok(lock) = min.data.lock() else {
+            bail!("lock was poisoned")
+        };
+        let id = max.id.load(Ordering::Acquire) + 1;
+        min.id.store(id, Ordering::Release);
+        Ok((lock, id))
+    }
+}
+
+#[derive(Debug)]
+struct Buffer {
+    data: Mutex<Vec<u8>>,
+    id: AtomicU64,
+}
+impl Buffer {
+    fn new(id: u64) -> Self {
+        Self {
+            data: Mutex::new(vec![0; 384 * 224 * 2]),
+            id: AtomicU64::new(id),
+        }
+    }
+}

src/input.rs

@@ -0,0 +1,456 @@
+use std::{
+    collections::{hash_map::Entry, HashMap},
+    fmt::Display,
+    str::FromStr,
+    sync::{Arc, RwLock},
+};
+
+use anyhow::anyhow;
+use gilrs::{ev::Code, Axis, Button, Gamepad, GamepadId};
+use serde::{Deserialize, Serialize};
+use winit::keyboard::{KeyCode, PhysicalKey};
+
+use crate::{
+    emulator::{SimId, VBKey},
+    persistence::Persistence,
+};
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+struct DeviceId(u16, u16);
+
+impl FromStr for DeviceId {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut ids = s.split("-");
+        let vendor_id: u16 = ids.next().ok_or(anyhow!("missing vendor id"))?.parse()?;
+        let product_id: u16 = ids.next().ok_or(anyhow!("missing product id"))?.parse()?;
+        Ok(Self(vendor_id, product_id))
+    }
+}
+
+impl Display for DeviceId {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_fmt(format_args!("{}-{}", self.0, self.1))
+    }
+}
+
+#[derive(Clone)]
+pub struct GamepadInfo {
+    pub id: GamepadId,
+    pub name: String,
+    device_id: DeviceId,
+    pub bound_to: Option<SimId>,
+}
+
+pub trait Mappings {
+    fn mapping_names(&self) -> HashMap<VBKey, Vec<String>>;
+    fn clear_mappings(&mut self, key: VBKey);
+    fn clear_all_mappings(&mut self);
+    fn use_default_mappings(&mut self);
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct GamepadMapping {
+    buttons: HashMap<Code, VBKey>,
+    axes: HashMap<Code, (VBKey, VBKey)>,
+    default_buttons: HashMap<Code, VBKey>,
+    default_axes: HashMap<Code, (VBKey, VBKey)>,
+}
+
+impl GamepadMapping {
+    fn for_gamepad(gamepad: &Gamepad) -> Self {
+        let mut default_buttons = HashMap::new();
+        let mut default_button = |btn: Button, key: VBKey| {
+            if let Some(code) = gamepad.button_code(btn) {
+                default_buttons.insert(code, key);
+            }
+        };
+        default_button(Button::South, VBKey::A);
+        default_button(Button::West, VBKey::B);
+        default_button(Button::RightTrigger, VBKey::RT);
+        default_button(Button::LeftTrigger, VBKey::LT);
+        default_button(Button::Start, VBKey::STA);
+        default_button(Button::Select, VBKey::SEL);
+
+        let mut default_axes = HashMap::new();
+        let mut default_axis = |axis: Axis, neg: VBKey, pos: VBKey| {
+            if let Some(code) = gamepad.axis_code(axis) {
+                default_axes.insert(code, (neg, pos));
+            }
+        };
+        default_axis(Axis::LeftStickX, VBKey::LL, VBKey::LR);
+        default_axis(Axis::LeftStickY, VBKey::LD, VBKey::LU);
+        default_axis(Axis::RightStickX, VBKey::RL, VBKey::RR);
+        default_axis(Axis::RightStickY, VBKey::RD, VBKey::RU);
+        default_axis(Axis::DPadX, VBKey::LL, VBKey::LR);
+        default_axis(Axis::DPadY, VBKey::LD, VBKey::LU);
+
+        Self {
+            buttons: default_buttons.clone(),
+            axes: default_axes.clone(),
+            default_buttons,
+            default_axes,
+        }
+    }
+
+    pub fn add_button_mapping(&mut self, key: VBKey, code: Code) {
+        let entry = self.buttons.entry(code).or_insert(VBKey::empty());
+        *entry = entry.union(key);
+    }
+
+    pub fn add_axis_neg_mapping(&mut self, key: VBKey, code: Code) {
+        let entry = self
+            .axes
+            .entry(code)
+            .or_insert((VBKey::empty(), VBKey::empty()));
+        entry.0 = entry.0.union(key);
+    }
+
+    pub fn add_axis_pos_mapping(&mut self, key: VBKey, code: Code) {
+        let entry = self
+            .axes
+            .entry(code)
+            .or_insert((VBKey::empty(), VBKey::empty()));
+        entry.1 = entry.1.union(key);
+    }
+
+    fn save_mappings(&self) -> PersistedGamepadMapping {
+        fn flatten<V: Copy>(values: &HashMap<Code, V>) -> Vec<(Code, V)> {
+            values.iter().map(|(k, v)| (*k, *v)).collect()
+        }
+        PersistedGamepadMapping {
+            buttons: flatten(&self.buttons),
+            axes: flatten(&self.axes),
+            default_buttons: flatten(&self.default_buttons),
+            default_axes: flatten(&self.default_axes),
+        }
+    }
+
+    fn from_mappings(mappings: &PersistedGamepadMapping) -> Self {
+        fn unflatten<V: Copy>(values: &[(Code, V)]) -> HashMap<Code, V> {
+            values.iter().map(|(k, v)| (*k, *v)).collect()
+        }
+        Self {
+            buttons: unflatten(&mappings.buttons),
+            axes: unflatten(&mappings.axes),
+            default_buttons: unflatten(&mappings.default_buttons),
+            default_axes: unflatten(&mappings.default_axes),
+        }
+    }
+}
+
+impl Mappings for GamepadMapping {
+    fn mapping_names(&self) -> HashMap<VBKey, Vec<String>> {
+        let mut results: HashMap<VBKey, Vec<String>> = HashMap::new();
+        for (axis, (left_keys, right_keys)) in &self.axes {
+            for key in left_keys.iter() {
+                results.entry(key).or_default().push(format!("-{axis}"));
+            }
+            for key in right_keys.iter() {
+                results.entry(key).or_default().push(format!("+{axis}"));
+            }
+        }
+        for (button, keys) in &self.buttons {
+            for key in keys.iter() {
+                results.entry(key).or_default().push(format!("{button}"));
+            }
+        }
+        results
+    }
+
+    fn clear_mappings(&mut self, key: VBKey) {
+        self.axes.retain(|_, (left, right)| {
+            *left = left.difference(key);
+            *right = right.difference(key);
+            !(left.is_empty() && right.is_empty())
+        });
+        self.buttons.retain(|_, keys| {
+            *keys = keys.difference(key);
+            !keys.is_empty()
+        });
+    }
+
+    fn clear_all_mappings(&mut self) {
+        self.axes.clear();
+        self.buttons.clear();
+    }
+
+    fn use_default_mappings(&mut self) {
+        self.axes = self.default_axes.clone();
+        self.buttons = self.default_buttons.clone();
+    }
+}
+
+#[derive(Default)]
+pub struct InputMapping {
+    keys: HashMap<PhysicalKey, VBKey>,
+    gamepads: HashMap<GamepadId, Arc<RwLock<GamepadMapping>>>,
+}
+
+impl InputMapping {
+    pub fn map_keyboard(&self, key: &PhysicalKey) -> Option<VBKey> {
+        self.keys.get(key).copied()
+    }
+
+    pub fn map_button(&self, id: &GamepadId, code: &Code) -> Option<VBKey> {
+        let mappings = self.gamepads.get(id)?.read().unwrap();
+        mappings.buttons.get(code).copied()
+    }
+
+    pub fn map_axis(&self, id: &GamepadId, code: &Code) -> Option<(VBKey, VBKey)> {
+        let mappings = self.gamepads.get(id)?.read().unwrap();
+        mappings.axes.get(code).copied()
+    }
+
+    pub fn add_keyboard_mapping(&mut self, key: VBKey, keyboard_key: PhysicalKey) {
+        let entry = self.keys.entry(keyboard_key).or_insert(VBKey::empty());
+        *entry = entry.union(key);
+    }
+
+    fn save_mappings(&self) -> PersistedKeyboardMapping {
+        PersistedKeyboardMapping {
+            keys: self.keys.iter().map(|(k, v)| (*k, *v)).collect(),
+        }
+    }
+
+    fn restore_mappings(&mut self, persisted: &PersistedKeyboardMapping) {
+        self.keys = persisted.keys.iter().map(|(k, v)| (*k, *v)).collect();
+    }
+}
+
+impl Mappings for InputMapping {
+    fn mapping_names(&self) -> HashMap<VBKey, Vec<String>> {
+        let mut results: HashMap<VBKey, Vec<String>> = HashMap::new();
+        for (keyboard_key, keys) in &self.keys {
+            let name = match keyboard_key {
+                PhysicalKey::Code(code) => format!("{code:?}"),
+                k => format!("{:?}", k),
+            };
+            for key in keys.iter() {
+                results.entry(key).or_default().push(name.clone());
+            }
+        }
+        results
+    }
+
+    fn clear_mappings(&mut self, key: VBKey) {
+        self.keys.retain(|_, keys| {
+            *keys = keys.difference(key);
+            !keys.is_empty()
+        });
+    }
+
+    fn clear_all_mappings(&mut self) {
+        self.keys.clear();
+    }
+
+    fn use_default_mappings(&mut self) {
+        self.keys.clear();
+        let mut default_key = |code, key| {
+            self.keys.insert(PhysicalKey::Code(code), key);
+        };
+        default_key(KeyCode::KeyA, VBKey::SEL);
+        default_key(KeyCode::KeyS, VBKey::STA);
+        default_key(KeyCode::KeyD, VBKey::B);
+        default_key(KeyCode::KeyF, VBKey::A);
+        default_key(KeyCode::KeyE, VBKey::LT);
+        default_key(KeyCode::KeyR, VBKey::RT);
+        default_key(KeyCode::KeyI, VBKey::RU);
+        default_key(KeyCode::KeyJ, VBKey::RL);
+        default_key(KeyCode::KeyK, VBKey::RD);
+        default_key(KeyCode::KeyL, VBKey::RR);
+        default_key(KeyCode::ArrowUp, VBKey::LU);
+        default_key(KeyCode::ArrowLeft, VBKey::LL);
+        default_key(KeyCode::ArrowDown, VBKey::LD);
+        default_key(KeyCode::ArrowRight, VBKey::LR);
+    }
+}
+
+#[derive(Clone)]
+pub struct MappingProvider {
+    persistence: Persistence,
+    device_mappings: Arc<RwLock<HashMap<DeviceId, Arc<RwLock<GamepadMapping>>>>>,
+    sim_mappings: HashMap<SimId, Arc<RwLock<InputMapping>>>,
+    gamepad_info: Arc<RwLock<HashMap<GamepadId, GamepadInfo>>>,
+}
+
+impl MappingProvider {
+    pub fn new(persistence: Persistence) -> Self {
+        let mut sim_mappings = HashMap::new();
+        let mut device_mappings = HashMap::new();
+
+        let mut p1_mappings = InputMapping::default();
+        let mut p2_mappings = InputMapping::default();
+
+        if let Ok(persisted) = persistence.load_config::<PersistedInputMappings>("mappings") {
+            p1_mappings.restore_mappings(&persisted.p1_keyboard);
+            p2_mappings.restore_mappings(&persisted.p2_keyboard);
+
+            for (device_id, mappings) in persisted.gamepads {
+                let Ok(device_id) = device_id.parse::<DeviceId>() else {
+                    continue;
+                };
+                let gamepad = GamepadMapping::from_mappings(&mappings);
+                device_mappings.insert(device_id, Arc::new(RwLock::new(gamepad)));
+            }
+        } else {
+            p1_mappings.use_default_mappings();
+        }
+
+        sim_mappings.insert(SimId::Player1, Arc::new(RwLock::new(p1_mappings)));
+        sim_mappings.insert(SimId::Player2, Arc::new(RwLock::new(p2_mappings)));
+        Self {
+            persistence,
+            device_mappings: Arc::new(RwLock::new(device_mappings)),
+            gamepad_info: Arc::new(RwLock::new(HashMap::new())),
+            sim_mappings,
+        }
+    }
+
+    pub fn for_sim(&self, sim_id: SimId) -> &Arc<RwLock<InputMapping>> {
+        self.sim_mappings.get(&sim_id).unwrap()
+    }
+
+    pub fn for_gamepad(&self, gamepad_id: GamepadId) -> Option<Arc<RwLock<GamepadMapping>>> {
+        let lock = self.gamepad_info.read().unwrap();
+        let device_id = lock.get(&gamepad_id)?.device_id.clone();
+        drop(lock);
+        let lock = self.device_mappings.read().unwrap();
+        lock.get(&device_id).cloned()
+    }
+
+    pub fn handle_gamepad_connect(&self, gamepad: &Gamepad) {
+        let device_id = DeviceId(
+            gamepad.vendor_id().unwrap_or_default(),
+            gamepad.product_id().unwrap_or_default(),
+        );
+        let mut lock = self.device_mappings.write().unwrap();
+        let mappings = match lock.entry(device_id.clone()) {
+            Entry::Vacant(entry) => {
+                let mappings = GamepadMapping::for_gamepad(gamepad);
+                entry.insert(Arc::new(RwLock::new(mappings)))
+            }
+            Entry::Occupied(entry) => entry.into_mut(),
+        }
+        .clone();
+        drop(lock);
+        let mut lock = self.gamepad_info.write().unwrap();
+        let bound_to = SimId::values()
+            .into_iter()
+            .find(|sim_id| lock.values().all(|info| info.bound_to != Some(*sim_id)));
+        if let Entry::Vacant(entry) = lock.entry(gamepad.id()) {
+            let info = GamepadInfo {
+                id: *entry.key(),
+                name: gamepad.name().to_string(),
+                device_id,
+                bound_to,
+            };
+            entry.insert(info);
+        }
+        drop(lock);
+        if let Some(sim_id) = bound_to {
+            self.for_sim(sim_id)
+                .write()
+                .unwrap()
+                .gamepads
+                .insert(gamepad.id(), mappings);
+        }
+    }
+
+    pub fn handle_gamepad_disconnect(&self, gamepad_id: GamepadId) {
+        let mut lock = self.gamepad_info.write().unwrap();
+        let Some(info) = lock.remove(&gamepad_id) else {
+            return;
+        };
+        if let Some(sim_id) = info.bound_to {
+            self.for_sim(sim_id)
+                .write()
+                .unwrap()
+                .gamepads
+                .remove(&gamepad_id);
+        }
+    }
+
+    pub fn assign_gamepad(&self, gamepad_id: GamepadId, sim_id: SimId) {
+        self.unassign_gamepad(gamepad_id);
+        let mut lock = self.gamepad_info.write().unwrap();
+        let Some(info) = lock.get_mut(&gamepad_id) else {
+            return;
+        };
+        info.bound_to = Some(sim_id);
+        let device_id = info.device_id.clone();
+        drop(lock);
+        let Some(device_mappings) = self
+            .device_mappings
+            .write()
+            .unwrap()
+            .get(&device_id)
+            .cloned()
+        else {
+            return;
+        };
+        self.for_sim(sim_id)
+            .write()
+            .unwrap()
+            .gamepads
+            .insert(gamepad_id, device_mappings);
+    }
+
+    pub fn unassign_gamepad(&self, gamepad_id: GamepadId) {
+        let mut lock = self.gamepad_info.write().unwrap();
+        let Some(info) = lock.get_mut(&gamepad_id) else {
+            return;
+        };
+        if let Some(sim_id) = info.bound_to {
+            let mut sim_mapping = self.for_sim(sim_id).write().unwrap();
+            sim_mapping.gamepads.remove(&gamepad_id);
+        }
+        info.bound_to = None;
+    }
+
+    pub fn gamepad_info(&self) -> Vec<GamepadInfo> {
+        self.gamepad_info
+            .read()
+            .unwrap()
+            .values()
+            .cloned()
+            .collect()
+    }
+
+    pub fn save(&self) {
+        let p1_keyboard = self.for_sim(SimId::Player1).read().unwrap().save_mappings();
+        let p2_keyboard = self.for_sim(SimId::Player2).read().unwrap().save_mappings();
+        let mut gamepads = HashMap::new();
+        for (device_id, gamepad) in self.device_mappings.read().unwrap().iter() {
+            let mapping = gamepad.read().unwrap().save_mappings();
+            gamepads.insert(device_id.to_string(), mapping);
+        }
+        let persisted = PersistedInputMappings {
+            p1_keyboard,
+            p2_keyboard,
+            gamepads,
+        };
+        let _ = self.persistence.save_config("mappings", &persisted);
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+struct PersistedInputMappings {
+    p1_keyboard: PersistedKeyboardMapping,
+    p2_keyboard: PersistedKeyboardMapping,
+    gamepads: HashMap<String, PersistedGamepadMapping>,
+}
+
+#[derive(Serialize, Deserialize)]
+struct PersistedKeyboardMapping {
+    keys: Vec<(PhysicalKey, VBKey)>,
+}
+
+#[derive(Serialize, Deserialize)]
+struct PersistedGamepadMapping {
+    buttons: Vec<(Code, VBKey)>,
+    axes: Vec<(Code, (VBKey, VBKey))>,
+    default_buttons: Vec<(Code, VBKey)>,
+    default_axes: Vec<(Code, (VBKey, VBKey))>,
+}

src/main.rs

@@ -0,0 +1,127 @@
+// hide console in release mode
+#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
+
+use std::{path::PathBuf, process, time::SystemTime};
+
+use anyhow::{bail, Result};
+use app::Application;
+use clap::Parser;
+use emulator::EmulatorBuilder;
+use thread_priority::{ThreadBuilder, ThreadPriority};
+use tracing::error;
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilter, Layer};
+use winit::event_loop::{ControlFlow, EventLoop};
+
+mod app;
+mod audio;
+mod controller;
+mod emulator;
+mod gdbserver;
+mod graphics;
+mod input;
+mod persistence;
+mod window;
+
+#[derive(Parser)]
+struct Args {
+    /// The path to a virtual boy ROM to run.
+    rom: Option<PathBuf>,
+    /// Start a GDB/LLDB debug server on this port.
+    #[arg(short, long)]
+    debug_port: Option<u16>,
+}
+
+fn init_logger() {
+    let directives = std::env::var("RUST_LOG").unwrap_or("error,lemur=info".into());
+    let filter = EnvFilter::builder().parse_lossy(directives);
+    let layer = tracing_subscriber::fmt::layer().with_filter(filter);
+    tracing_subscriber::registry().with(layer).init();
+}
+
+fn set_panic_handler() {
+    std::panic::set_hook(Box::new(|info| {
+        let mut message = String::new();
+        if let Some(msg) = info.payload().downcast_ref::<&str>() {
+            message += &format!("{}\n", msg);
+        } else if let Some(msg) = info.payload().downcast_ref::<String>() {
+            message += &format!("{}\n", msg);
+        }
+        if let Some(location) = info.location() {
+            message += &format!(
+                "    in file '{}' at line {}\n",
+                location.file(),
+                location.line()
+            );
+        }
+        let backtrace = std::backtrace::Backtrace::force_capture();
+        message += &format!("stack trace:\n{:#}\n", backtrace);
+
+        eprint!("{}", message);
+
+        let Some(project_dirs) = directories::ProjectDirs::from("com", "virtual-boy", "Lemur")
+        else {
+            return;
+        };
+        let data_dir = project_dirs.data_dir();
+        if std::fs::create_dir_all(data_dir).is_err() {
+            return;
+        }
+        let timestamp = SystemTime::now()
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap()
+            .as_millis();
+        let logfile_name = format!("crash-{}.txt", timestamp);
+        let _ = std::fs::write(data_dir.join(logfile_name), message);
+    }));
+}
+
+#[cfg(windows)]
+fn set_process_priority_to_high() -> Result<()> {
+    use windows::Win32::{Foundation, System::Threading};
+    let process = unsafe { Threading::GetCurrentProcess() };
+    unsafe { Threading::SetPriorityClass(process, Threading::HIGH_PRIORITY_CLASS)? };
+    unsafe { Foundation::CloseHandle(process)? };
+    Ok(())
+}
+
+fn main() -> Result<()> {
+    init_logger();
+
+    set_panic_handler();
+
+    #[cfg(windows)]
+    set_process_priority_to_high()?;
+
+    let args = Args::parse();
+
+    let (mut builder, client) = EmulatorBuilder::new();
+    if let Some(path) = &args.rom {
+        builder = builder.with_rom(path);
+    }
+    if args.debug_port.is_some() {
+        if args.rom.is_none() {
+            bail!("to start debugging, please select a game.");
+        }
+        builder = builder.start_paused(true);
+    }
+
+    ThreadBuilder::default()
+        .name("Emulator".to_owned())
+        .priority(ThreadPriority::Max)
+        .spawn_careless(move || {
+            let mut emulator = match builder.build() {
+                Ok(e) => e,
+                Err(error) => {
+                    error!(%error, "Error initializing emulator");
+                    process::exit(1);
+                }
+            };
+            emulator.run();
+        })?;
+
+    let event_loop = EventLoop::with_user_event().build().unwrap();
+    event_loop.set_control_flow(ControlFlow::Poll);
+    let proxy = event_loop.create_proxy();
+    event_loop.run_app(&mut Application::new(client, proxy, args.debug_port))?;
+    Ok(())
+}

src/persistence.rs

@@ -0,0 +1,46 @@
+use std::{fs, path::PathBuf};
+
+use anyhow::{bail, Result};
+use directories::ProjectDirs;
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone)]
+pub struct Persistence {
+    dirs: Option<Dirs>,
+}
+
+impl Persistence {
+    pub fn new() -> Self {
+        Self { dirs: init_dirs() }
+    }
+
+    pub fn save_config<T: Serialize>(&self, file: &str, data: &T) -> Result<()> {
+        if let Some(dirs) = self.dirs.as_ref() {
+            let bytes = serde_json::to_vec_pretty(data)?;
+            let filename = dirs.config_dir.join(file).with_extension("json");
+            fs::write(&filename, bytes)?;
+        }
+        Ok(())
+    }
+
+    pub fn load_config<T: for<'a> Deserialize<'a>>(&self, file: &str) -> Result<T> {
+        let Some(dirs) = self.dirs.as_ref() else {
+            bail!("config directory not found");
+        };
+        let filename = dirs.config_dir.join(file).with_extension("json");
+        let bytes = fs::read(filename)?;
+        Ok(serde_json::from_slice(&bytes)?)
+    }
+}
+
+#[derive(Clone)]
+struct Dirs {
+    config_dir: PathBuf,
+}
+
+fn init_dirs() -> Option<Dirs> {
+    let dirs = ProjectDirs::from("com", "virtual-boy", "Lemur")?;
+    let config_dir = dirs.config_dir().to_path_buf();
+    fs::create_dir_all(&config_dir).ok()?;
+    Some(Dirs { config_dir })
+}

src/window.rs

@@ -0,0 +1,33 @@
+pub use about::AboutWindow;
+use egui::{Context, ViewportBuilder, ViewportId};
+pub use game::GameWindow;
+pub use gdb::GdbServerWindow;
+pub use input::InputWindow;
+use winit::event::KeyEvent;
+
+use crate::emulator::SimId;
+
+mod about;
+mod game;
+mod game_screen;
+mod gdb;
+mod input;
+
+pub trait AppWindow {
+    fn viewport_id(&self) -> ViewportId;
+    fn sim_id(&self) -> SimId {
+        SimId::Player1
+    }
+    fn initial_viewport(&self) -> ViewportBuilder;
+    fn show(&mut self, ctx: &Context);
+    fn on_init(&mut self, render_state: &egui_wgpu::RenderState) {
+        let _ = render_state;
+    }
+    fn on_destroy(&mut self) {}
+    fn handle_key_event(&mut self, event: &KeyEvent) {
+        let _ = event;
+    }
+    fn handle_gamepad_event(&mut self, event: &gilrs::Event) {
+        let _ = event;
+    }
+}

src/window/about.rs

@@ -0,0 +1,31 @@
+use egui::{CentralPanel, Context, Image, ViewportBuilder, ViewportId};
+
+use super::AppWindow;
+
+pub struct AboutWindow;
+
+impl AppWindow for AboutWindow {
+    fn viewport_id(&self) -> ViewportId {
+        ViewportId::from_hash_of("About")
+    }
+
+    fn initial_viewport(&self) -> ViewportBuilder {
+        ViewportBuilder::default()
+            .with_title("About Lemur")
+            .with_inner_size((300.0, 200.0))
+    }
+
+    fn show(&mut self, ctx: &Context) {
+        CentralPanel::default().show(ctx, |ui| {
+            ui.vertical_centered(|ui| {
+                ui.label("Lemur Virtual Boy Emulator");
+                ui.label(format!("Version {}", env!("CARGO_PKG_VERSION")));
+                ui.hyperlink("https://git.virtual-boy.com/PVB/lemur");
+                let logo = Image::new(egui::include_image!("../../assets/lemur-256x256.png"))
+                    .max_width(256.0)
+                    .maintain_aspect_ratio(true);
+                ui.add(logo);
+            });
+        });
+    }
+}

src/window/game.rs

@@ -0,0 +1,462 @@
+use std::sync::mpsc;
+
+use crate::{
+    app::UserEvent,
+    emulator::{EmulatorClient, EmulatorCommand, EmulatorState, SimId, SimState},
+    persistence::Persistence,
+};
+use egui::{
+    ecolor::HexColor, menu, Align2, Button, CentralPanel, Color32, Context, Direction, Frame,
+    Layout, Response, Sense, TopBottomPanel, Ui, Vec2, ViewportBuilder, ViewportCommand,
+    ViewportId, WidgetText, Window,
+};
+use egui_toast::{Toast, Toasts};
+use serde::{Deserialize, Serialize};
+use winit::event_loop::EventLoopProxy;
+
+use super::{
+    game_screen::{DisplayMode, GameScreen},
+    AppWindow,
+};
+
+const COLOR_PRESETS: [[Color32; 2]; 3] = [
+    [
+        Color32::from_rgb(0xff, 0x00, 0x00),
+        Color32::from_rgb(0x00, 0xc6, 0xf0),
+    ],
+    [
+        Color32::from_rgb(0x00, 0xb4, 0x00),
+        Color32::from_rgb(0xc8, 0x00, 0xff),
+    ],
+    [
+        Color32::from_rgb(0xb4, 0x9b, 0x00),
+        Color32::from_rgb(0x00, 0x00, 0xff),
+    ],
+];
+
+pub struct GameWindow {
+    client: EmulatorClient,
+    proxy: EventLoopProxy<UserEvent>,
+    persistence: Persistence,
+    sim_id: SimId,
+    config: GameConfig,
+    screen: Option<GameScreen>,
+    messages: Option<mpsc::Receiver<Toast>>,
+    color_picker: Option<ColorPickerState>,
+}
+
+impl GameWindow {
+    pub fn new(
+        client: EmulatorClient,
+        proxy: EventLoopProxy<UserEvent>,
+        persistence: Persistence,
+        sim_id: SimId,
+    ) -> Self {
+        let config = load_config(&persistence, sim_id);
+        Self {
+            client,
+            proxy,
+            persistence,
+            sim_id,
+            config,
+            screen: None,
+            messages: None,
+            color_picker: None,
+        }
+    }
+
+    fn show_menu(&mut self, ctx: &Context, ui: &mut Ui) {
+        ui.menu_button("ROM", |ui| {
+            if ui.button("Open ROM").clicked() {
+                let rom = rfd::FileDialog::new()
+                    .add_filter("Virtual Boy ROMs", &["vb", "vbrom"])
+                    .pick_file();
+                if let Some(path) = rom {
+                    self.client
+                        .send_command(EmulatorCommand::LoadGame(self.sim_id, path));
+                }
+                ui.close_menu();
+            }
+            if ui.button("Quit").clicked() {
+                let _ = self.proxy.send_event(UserEvent::Quit(self.sim_id));
+            }
+        });
+        ui.menu_button("Emulation", |ui| {
+            let state = self.client.emulator_state();
+            let is_ready = self.client.sim_state(self.sim_id) == SimState::Ready;
+            let can_pause = is_ready && state == EmulatorState::Running;
+            let can_resume = is_ready && state == EmulatorState::Paused;
+            if state == EmulatorState::Running {
+                if ui.add_enabled(can_pause, Button::new("Pause")).clicked() {
+                    self.client.send_command(EmulatorCommand::Pause);
+                    ui.close_menu();
+                }
+            } else if ui.add_enabled(can_resume, Button::new("Resume")).clicked() {
+                self.client.send_command(EmulatorCommand::Resume);
+                ui.close_menu();
+            }
+            if ui.add_enabled(is_ready, Button::new("Reset")).clicked() {
+                self.client
+                    .send_command(EmulatorCommand::Reset(self.sim_id));
+                ui.close_menu();
+            }
+        });
+        ui.menu_button("Options", |ui| self.show_options_menu(ctx, ui));
+        ui.menu_button("Multiplayer", |ui| {
+            let has_player_2 = self.client.sim_state(SimId::Player2) != SimState::Uninitialized;
+            if self.sim_id == SimId::Player1
+                && !has_player_2
+                && ui.button("Open Player 2").clicked()
+            {
+                self.client
+                    .send_command(EmulatorCommand::StartSecondSim(None));
+                self.proxy.send_event(UserEvent::OpenPlayer2).unwrap();
+                ui.close_menu();
+            }
+            if has_player_2 {
+                let linked = self.client.are_sims_linked();
+                if linked && ui.button("Unlink").clicked() {
+                    self.client.send_command(EmulatorCommand::Unlink);
+                    ui.close_menu();
+                }
+                if !linked && ui.button("Link").clicked() {
+                    self.client.send_command(EmulatorCommand::Link);
+                    ui.close_menu();
+                }
+            }
+        });
+        ui.menu_button("Tools", |ui| {
+            if ui.button("GDB Server").clicked() {
+                self.proxy
+                    .send_event(UserEvent::OpenDebugger(self.sim_id))
+                    .unwrap();
+                ui.close_menu();
+            }
+        });
+        ui.menu_button("About", |ui| {
+            self.proxy.send_event(UserEvent::OpenAbout).unwrap();
+            ui.close_menu();
+        });
+    }
+
+    fn show_options_menu(&mut self, ctx: &Context, ui: &mut Ui) {
+        ui.menu_button("Video", |ui| {
+            ui.menu_button("Screen Size", |ui| {
+                let current_dims = self.config.dimensions;
+
+                for scale in 1..=4 {
+                    let label = format!("x{scale}");
+                    let scale = scale as f32;
+                    let dims = {
+                        let Vec2 { x, y } = self.config.display_mode.proportions();
+                        Vec2::new(x * scale, y * scale + 22.0)
+                    };
+                    if ui
+                        .selectable_button((current_dims - dims).length() < 1.0, label)
+                        .clicked()
+                    {
+                        ctx.send_viewport_cmd(ViewportCommand::InnerSize(dims));
+                        ui.close_menu();
+                    }
+                }
+            });
+
+            ui.menu_button("Display Mode", |ui| {
+                let old_proportions = self.config.display_mode.proportions();
+                let mut changed = false;
+                let mut display_mode = self.config.display_mode;
+                changed |= ui
+                    .selectable_option(&mut display_mode, DisplayMode::Anaglyph, "Anaglyph")
+                    .clicked();
+                changed |= ui
+                    .selectable_option(&mut display_mode, DisplayMode::LeftEye, "Left Eye")
+                    .clicked();
+                changed |= ui
+                    .selectable_option(&mut display_mode, DisplayMode::RightEye, "Right Eye")
+                    .clicked();
+                changed |= ui
+                    .selectable_option(&mut display_mode, DisplayMode::SideBySide, "Side by Side")
+                    .clicked();
+
+                if !changed {
+                    return;
+                }
+
+                let current_dims = self.config.dimensions;
+                let new_proportions = display_mode.proportions();
+                let scale = new_proportions / old_proportions;
+                if scale != Vec2::new(1.0, 1.0) {
+                    ctx.send_viewport_cmd(ViewportCommand::InnerSize(current_dims * scale));
+                }
+
+                self.update_config(|c| {
+                    c.display_mode = display_mode;
+                    c.dimensions = current_dims * scale;
+                });
+                ui.close_menu();
+            });
+            ui.menu_button("Colors", |ui| {
+                for preset in COLOR_PRESETS {
+                    if ui.color_pair_button(preset[0], preset[1]).clicked() {
+                        self.update_config(|c| c.colors = preset);
+                        ui.close_menu();
+                    }
+                }
+                ui.with_layout(ui.layout().with_cross_align(egui::Align::Center), |ui| {
+                    if ui.button("Custom").clicked() {
+                        let color_str = |color: Color32| {
+                            format!("{:02x}{:02x}{:02x}", color.r(), color.g(), color.b())
+                        };
+                        let is_running = self.client.emulator_state() == EmulatorState::Running;
+                        if is_running {
+                            self.client.send_command(EmulatorCommand::Pause);
+                        }
+                        let color_codes = [
+                            color_str(self.config.colors[0]),
+                            color_str(self.config.colors[1]),
+                        ];
+                        self.color_picker = Some(ColorPickerState {
+                            color_codes,
+                            just_opened: true,
+                            unpause_on_close: is_running,
+                        });
+                        ui.close_menu();
+                    }
+                });
+            });
+        });
+        ui.menu_button("Audio", |ui| {
+            let p1_enabled = self.client.is_audio_enabled(SimId::Player1);
+            let p2_enabled = self.client.is_audio_enabled(SimId::Player2);
+            if ui.selectable_button(p1_enabled, "Player 1").clicked() {
+                self.client
+                    .send_command(EmulatorCommand::SetAudioEnabled(!p1_enabled, p2_enabled));
+                ui.close_menu();
+            }
+            if ui.selectable_button(p2_enabled, "Player 2").clicked() {
+                self.client
+                    .send_command(EmulatorCommand::SetAudioEnabled(p1_enabled, !p2_enabled));
+                ui.close_menu();
+            }
+        });
+        ui.menu_button("Input", |ui| {
+            if ui.button("Bind Inputs").clicked() {
+                self.proxy.send_event(UserEvent::OpenInput).unwrap();
+                ui.close_menu();
+            }
+        });
+    }
+
+    fn show_color_picker(&mut self, ui: &mut Ui) {
+        let mut colors = self.config.colors;
+        let Some(state) = self.color_picker.as_mut() else {
+            return;
+        };
+        let (open, updated) = ui
+            .horizontal(|ui| {
+                let left_color = ui.color_picker(&mut colors[0], &mut state.color_codes[0]);
+                if state.just_opened {
+                    left_color.request_focus();
+                    state.just_opened = false;
+                }
+                let right_color = ui.color_picker(&mut colors[1], &mut state.color_codes[1]);
+                let open = left_color.has_focus() || right_color.has_focus();
+                let updated = left_color.changed() || right_color.changed();
+                (open, updated)
+            })
+            .inner;
+        if !open {
+            if state.unpause_on_close {
+                self.client.send_command(EmulatorCommand::Resume);
+            }
+            self.color_picker = None;
+        }
+        if updated {
+            self.update_config(|c| c.colors = colors);
+        }
+    }
+
+    fn update_config(&mut self, update: impl FnOnce(&mut GameConfig)) {
+        let mut new_config = self.config.clone();
+        update(&mut new_config);
+        if self.config != new_config {
+            let _ = self
+                .persistence
+                .save_config(config_filename(self.sim_id), &new_config);
+        }
+        self.config = new_config;
+    }
+}
+
+fn config_filename(sim_id: SimId) -> &'static str {
+    match sim_id {
+        SimId::Player1 => "config_p1",
+        SimId::Player2 => "config_p2",
+    }
+}
+
+fn load_config(persistence: &Persistence, sim_id: SimId) -> GameConfig {
+    if let Ok(config) = persistence.load_config(config_filename(sim_id)) {
+        return config;
+    }
+    GameConfig {
+        display_mode: DisplayMode::Anaglyph,
+        colors: COLOR_PRESETS[0],
+        dimensions: DisplayMode::Anaglyph.proportions() + Vec2::new(0.0, 22.0),
+    }
+}
+
+impl AppWindow for GameWindow {
+    fn viewport_id(&self) -> ViewportId {
+        match self.sim_id {
+            SimId::Player1 => ViewportId::ROOT,
+            SimId::Player2 => ViewportId::from_hash_of("Player2"),
+        }
+    }
+
+    fn sim_id(&self) -> SimId {
+        self.sim_id
+    }
+
+    fn initial_viewport(&self) -> ViewportBuilder {
+        ViewportBuilder::default()
+            .with_title("Lemur")
+            .with_inner_size(self.config.dimensions)
+    }
+
+    fn show(&mut self, ctx: &Context) {
+        let dimensions = {
+            let bounds = ctx.available_rect();
+            bounds.max - bounds.min
+        };
+        self.update_config(|c| c.dimensions = dimensions);
+
+        let mut toasts = Toasts::new()
+            .anchor(Align2::LEFT_BOTTOM, (10.0, 10.0))
+            .direction(Direction::BottomUp);
+        if let Some(messages) = self.messages.as_mut() {
+            while let Ok(toast) = messages.try_recv() {
+                toasts.add(toast);
+            }
+        }
+        TopBottomPanel::top("menubar")
+            .exact_height(22.0)
+            .show(ctx, |ui| {
+                menu::bar(ui, |ui| {
+                    self.show_menu(ctx, ui);
+                });
+            });
+        if self.color_picker.is_some() {
+            Window::new("Color Picker")
+                .title_bar(false)
+                .resizable(false)
+                .anchor(Align2::CENTER_CENTER, Vec2::ZERO)
+                .show(ctx, |ui| {
+                    self.show_color_picker(ui);
+                });
+        }
+        let frame = Frame::central_panel(&ctx.style()).fill(Color32::BLACK);
+        CentralPanel::default().frame(frame).show(ctx, |ui| {
+            if let Some(screen) = self.screen.as_mut() {
+                screen.update(self.config.display_mode, self.config.colors);
+                ui.add(screen);
+            }
+        });
+        toasts.show(ctx);
+    }
+
+    fn on_init(&mut self, render_state: &egui_wgpu::RenderState) {
+        let (screen, sink) = GameScreen::init(render_state);
+        let (message_sink, message_source) = mpsc::channel();
+        self.client.send_command(EmulatorCommand::ConnectToSim(
+            self.sim_id,
+            sink,
+            message_sink,
+        ));
+        self.screen = Some(screen);
+        self.messages = Some(message_source);
+    }
+
+    fn on_destroy(&mut self) {
+        if self.sim_id == SimId::Player2 {
+            self.client.send_command(EmulatorCommand::StopSecondSim);
+        }
+        let _ = self.proxy.send_event(UserEvent::Quit(self.sim_id));
+    }
+}
+
+trait UiExt {
+    fn selectable_button(&mut self, selected: bool, text: impl Into<WidgetText>) -> Response;
+    fn selectable_option<T: Eq>(
+        &mut self,
+        current_value: &mut T,
+        selected_value: T,
+        text: impl Into<WidgetText>,
+    ) -> Response {
+        let response = self.selectable_button(*current_value == selected_value, text);
+        if response.clicked() {
+            *current_value = selected_value;
+        }
+        response
+    }
+
+    fn color_pair_button(&mut self, left: Color32, right: Color32) -> Response;
+
+    fn color_picker(&mut self, color: &mut Color32, hex: &mut String) -> Response;
+}
+
+impl UiExt for Ui {
+    fn selectable_button(&mut self, selected: bool, text: impl Into<WidgetText>) -> Response {
+        self.style_mut().visuals.widgets.inactive.bg_fill = Color32::TRANSPARENT;
+        self.style_mut().visuals.widgets.hovered.bg_fill = Color32::TRANSPARENT;
+        self.style_mut().visuals.widgets.active.bg_fill = Color32::TRANSPARENT;
+        let mut selected = selected;
+        self.checkbox(&mut selected, text)
+    }
+
+    fn color_pair_button(&mut self, left: Color32, right: Color32) -> Response {
+        let button_size = Vec2::new(60.0, 20.0);
+        let (rect, response) = self.allocate_at_least(button_size, Sense::click());
+        let center_x = rect.center().x;
+        let left_rect = rect.with_max_x(center_x);
+        self.painter().rect_filled(left_rect, 0.0, left);
+        let right_rect = rect.with_min_x(center_x);
+        self.painter().rect_filled(right_rect, 0.0, right);
+
+        let style = self.style().interact(&response);
+        self.painter().rect_stroke(rect, 0.0, style.fg_stroke);
+        response
+    }
+
+    fn color_picker(&mut self, color: &mut Color32, hex: &mut String) -> Response {
+        self.allocate_ui_with_layout(
+            Vec2::new(100.0, 130.0),
+            Layout::top_down_justified(egui::Align::Center),
+            |ui| {
+                let (rect, _) = ui.allocate_at_least(Vec2::new(100.0, 100.0), Sense::hover());
+                ui.painter().rect_filled(rect, 0.0, *color);
+                let resp = ui.text_edit_singleline(hex);
+                if resp.changed() {
+                    if let Ok(new_color) = HexColor::from_str_without_hash(hex) {
+                        *color = new_color.color();
+                    }
+                }
+                resp
+            },
+        )
+        .inner
+    }
+}
+
+struct ColorPickerState {
+    color_codes: [String; 2],
+    just_opened: bool,
+    unpause_on_close: bool,
+}
+
+#[derive(Serialize, Deserialize, Clone, PartialEq, Eq)]
+struct GameConfig {
+    display_mode: DisplayMode,
+    colors: [Color32; 2],
+    dimensions: Vec2,
+}

src/window/game_screen.rs

@@ -0,0 +1,279 @@
+use std::{collections::HashMap, sync::Arc};
+
+use egui::{Color32, Rgba, Vec2, Widget};
+use serde::{Deserialize, Serialize};
+use wgpu::{util::DeviceExt as _, BindGroup, BindGroupLayout, Buffer, RenderPipeline};
+
+use crate::graphics::TextureSink;
+
+pub struct GameScreen {
+    bind_group: Arc<BindGroup>,
+    color_buffer: Arc<Buffer>,
+    display_mode: DisplayMode,
+    colors: Colors,
+}
+
+impl GameScreen {
+    fn init_pipeline(render_state: &egui_wgpu::RenderState) {
+        let device = &render_state.device;
+
+        let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            label: Some("texture bind group layout"),
+            entries: &[
+                wgpu::BindGroupLayoutEntry {
+                    binding: 0,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Texture {
+                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
+                        view_dimension: wgpu::TextureViewDimension::D2,
+                        multisampled: false,
+                    },
+                    count: None,
+                },
+                wgpu::BindGroupLayoutEntry {
+                    binding: 1,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                    count: None,
+                },
+                wgpu::BindGroupLayoutEntry {
+                    binding: 2,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Buffer {
+                        ty: wgpu::BufferBindingType::Uniform,
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                },
+            ],
+        });
+
+        let shader = device.create_shader_module(wgpu::include_wgsl!("../game.wgsl"));
+        let render_pipeline_layout =
+            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+                label: Some("render pipeline layout"),
+                bind_group_layouts: &[&bind_group_layout],
+                push_constant_ranges: &[],
+            });
+
+        let create_render_pipeline = |entry_point: &str| {
+            device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+                label: Some("render pipeline"),
+                layout: Some(&render_pipeline_layout),
+                vertex: wgpu::VertexState {
+                    module: &shader,
+                    entry_point: Some("vs_main"),
+                    buffers: &[],
+                    compilation_options: wgpu::PipelineCompilationOptions::default(),
+                },
+                fragment: Some(wgpu::FragmentState {
+                    module: &shader,
+                    entry_point: Some(entry_point),
+                    targets: &[Some(wgpu::ColorTargetState {
+                        format: wgpu::TextureFormat::Bgra8Unorm,
+                        blend: Some(wgpu::BlendState::REPLACE),
+                        write_mask: wgpu::ColorWrites::ALL,
+                    })],
+                    compilation_options: wgpu::PipelineCompilationOptions::default(),
+                }),
+                primitive: wgpu::PrimitiveState {
+                    topology: wgpu::PrimitiveTopology::TriangleList,
+                    strip_index_format: None,
+                    front_face: wgpu::FrontFace::Ccw,
+                    cull_mode: Some(wgpu::Face::Back),
+                    polygon_mode: wgpu::PolygonMode::Fill,
+                    unclipped_depth: false,
+                    conservative: false,
+                },
+                depth_stencil: None,
+                multisample: wgpu::MultisampleState {
+                    count: 1,
+                    mask: !0,
+                    alpha_to_coverage_enabled: false,
+                },
+                multiview: None,
+                cache: None,
+            })
+        };
+
+        let mut render_pipelines = HashMap::new();
+        render_pipelines.insert(DisplayMode::Anaglyph, create_render_pipeline("fs_anaglyph"));
+        render_pipelines.insert(DisplayMode::LeftEye, create_render_pipeline("fs_lefteye"));
+        render_pipelines.insert(DisplayMode::RightEye, create_render_pipeline("fs_righteye"));
+        render_pipelines.insert(
+            DisplayMode::SideBySide,
+            create_render_pipeline("fs_sidebyside"),
+        );
+
+        render_state
+            .renderer
+            .write()
+            .callback_resources
+            .insert(SharedGameScreenResources {
+                render_pipelines,
+                bind_group_layout,
+            });
+    }
+
+    pub fn init(render_state: &egui_wgpu::RenderState) -> (Self, TextureSink) {
+        Self::init_pipeline(render_state);
+
+        let device = &render_state.device;
+        let queue = &render_state.queue;
+
+        let (sink, texture_view) = TextureSink::new(device, queue.clone());
+        let sampler = device.create_sampler(&wgpu::SamplerDescriptor::default());
+        let colors = Colors::new(
+            Color32::from_rgb(0xff, 0x00, 0x00),
+            Color32::from_rgb(0x00, 0xc6, 0xf0),
+        );
+
+        let color_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("colors"),
+            contents: bytemuck::bytes_of(&colors),
+            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+        });
+
+        let renderer = render_state.renderer.read();
+        let resources: &SharedGameScreenResources = renderer.callback_resources.get().unwrap();
+
+        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label: Some("bind group"),
+            layout: &resources.bind_group_layout,
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: wgpu::BindingResource::TextureView(&texture_view),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 1,
+                    resource: wgpu::BindingResource::Sampler(&sampler),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 2,
+                    resource: color_buffer.as_entire_binding(),
+                },
+            ],
+        });
+
+        (
+            Self {
+                bind_group: Arc::new(bind_group),
+                color_buffer: Arc::new(color_buffer),
+                display_mode: DisplayMode::Anaglyph,
+                colors,
+            },
+            sink,
+        )
+    }
+
+    pub fn update(&mut self, display_mode: DisplayMode, colors: [Color32; 2]) {
+        self.display_mode = display_mode;
+        self.colors = Colors::new(colors[0], colors[1]);
+    }
+}
+
+impl Widget for &mut GameScreen {
+    fn ui(self, ui: &mut egui::Ui) -> egui::Response {
+        let response = ui.allocate_rect(ui.clip_rect(), egui::Sense::hover());
+        let callback = egui_wgpu::Callback::new_paint_callback(
+            response.rect,
+            GameScreenCallback {
+                bind_group: self.bind_group.clone(),
+                color_buffer: self.color_buffer.clone(),
+                display_mode: self.display_mode,
+                colors: self.colors,
+            },
+        );
+        ui.painter().add(callback);
+        response
+    }
+}
+
+struct GameScreenCallback {
+    bind_group: Arc<BindGroup>,
+    color_buffer: Arc<Buffer>,
+    display_mode: DisplayMode,
+    colors: Colors,
+}
+
+impl egui_wgpu::CallbackTrait for GameScreenCallback {
+    fn prepare(
+        &self,
+        _device: &wgpu::Device,
+        queue: &wgpu::Queue,
+        _screen_descriptor: &egui_wgpu::ScreenDescriptor,
+        _egui_encoder: &mut wgpu::CommandEncoder,
+        _callback_resources: &mut egui_wgpu::CallbackResources,
+    ) -> Vec<wgpu::CommandBuffer> {
+        queue.write_buffer(&self.color_buffer, 0, bytemuck::bytes_of(&self.colors));
+        vec![]
+    }
+    fn paint(
+        &self,
+        info: egui::PaintCallbackInfo,
+        render_pass: &mut wgpu::RenderPass<'static>,
+        callback_resources: &egui_wgpu::CallbackResources,
+    ) {
+        let resources: &SharedGameScreenResources = callback_resources.get().unwrap();
+        let viewport = info.viewport_in_pixels();
+        let left = viewport.left_px as f32;
+        let top = viewport.top_px as f32;
+        let width = viewport.width_px as f32;
+        let height = viewport.height_px as f32;
+        let aspect_ratio = {
+            let proportions = self.display_mode.proportions();
+            proportions.x / proportions.y
+        };
+        let w = width.min(height * aspect_ratio);
+        let h = height.min(width / aspect_ratio);
+        let x = left + (width - w) / 2.0;
+        let y = top + (height - h) / 2.0;
+        let pipeline = resources
+            .render_pipelines
+            .get(&self.display_mode)
+            .unwrap_or_else(|| panic!("Unrecognized display mode {:?}", self.display_mode));
+        render_pass.set_pipeline(pipeline);
+        render_pass.set_bind_group(0, Some(self.bind_group.as_ref()), &[]);
+        render_pass.set_viewport(x, y, w, h, 0.0, 1.0);
+        render_pass.draw(0..6, 0..1);
+    }
+}
+
+struct SharedGameScreenResources {
+    render_pipelines: HashMap<DisplayMode, RenderPipeline>,
+    bind_group_layout: BindGroupLayout,
+}
+
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+#[repr(C)]
+struct Colors {
+    left: Rgba,
+    right: Rgba,
+}
+impl Colors {
+    fn new(left: Color32, right: Color32) -> Self {
+        Self {
+            left: left.into(),
+            right: right.into(),
+        }
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Serialize, Deserialize)]
+pub enum DisplayMode {
+    Anaglyph,
+    LeftEye,
+    RightEye,
+    SideBySide,
+}
+
+impl DisplayMode {
+    pub fn proportions(self) -> Vec2 {
+        match self {
+            Self::SideBySide => Vec2::new(768.0, 224.0),
+            _ => Vec2::new(384.0, 224.0),
+        }
+    }
+}

src/window/gdb.rs

@@ -0,0 +1,111 @@
+use egui::{Button, CentralPanel, TextEdit, ViewportBuilder, ViewportId};
+use winit::event_loop::EventLoopProxy;
+
+use crate::{
+    app::UserEvent,
+    emulator::{EmulatorClient, SimId, SimState},
+    gdbserver::{GdbServer, GdbServerStatus},
+};
+
+use super::AppWindow;
+
+pub struct GdbServerWindow {
+    sim_id: SimId,
+    client: EmulatorClient,
+    port_str: String,
+    connected: bool,
+    quit_on_disconnect: bool,
+    server: GdbServer,
+    proxy: EventLoopProxy<UserEvent>,
+}
+
+impl GdbServerWindow {
+    pub fn new(sim_id: SimId, client: EmulatorClient, proxy: EventLoopProxy<UserEvent>) -> Self {
+        Self {
+            sim_id,
+            client: client.clone(),
+            port_str: (8080 + sim_id.to_index()).to_string(),
+            connected: false,
+            quit_on_disconnect: false,
+            server: GdbServer::new(sim_id, client),
+            proxy,
+        }
+    }
+
+    pub fn launch(&mut self, port: u16) {
+        self.server.stop();
+        self.port_str = port.to_string();
+        self.quit_on_disconnect = true;
+        self.server.start(port);
+        self.connected = true;
+    }
+}
+
+impl AppWindow for GdbServerWindow {
+    fn viewport_id(&self) -> ViewportId {
+        ViewportId::from_hash_of(format!("Debugger-{}", self.sim_id))
+    }
+
+    fn sim_id(&self) -> SimId {
+        self.sim_id
+    }
+
+    fn initial_viewport(&self) -> ViewportBuilder {
+        ViewportBuilder::default()
+            .with_title(format!("GDB Server ({})", self.sim_id))
+            .with_inner_size((300.0, 200.0))
+    }
+
+    fn show(&mut self, ctx: &egui::Context) {
+        let port_num: Option<u16> = self.port_str.parse().ok();
+        let status = self.server.status();
+        CentralPanel::default().show(ctx, |ui| {
+            ui.horizontal(|ui| {
+                if port_num.is_none() {
+                    let style = ui.style_mut();
+                    let error = style.visuals.error_fg_color;
+                    style.visuals.widgets.active.bg_stroke.color = error;
+                    style.visuals.widgets.hovered.bg_stroke.color = error;
+                }
+                ui.label("Port");
+                let port_editor = TextEdit::singleline(&mut self.port_str).desired_width(100.0);
+                ui.add_enabled(!status.running(), port_editor);
+                ui.checkbox(&mut self.quit_on_disconnect, "Quit on disconnect");
+            });
+
+            if !status.running() {
+                if self.connected && self.quit_on_disconnect {
+                    self.proxy.send_event(UserEvent::Quit(self.sim_id)).unwrap();
+                } else {
+                    self.connected = false;
+                }
+                let start_button = Button::new("Start");
+                let can_start =
+                    port_num.is_some() && self.client.sim_state(self.sim_id) == SimState::Ready;
+                if ui.add_enabled(can_start, start_button).clicked() {
+                    let port = port_num.unwrap();
+                    self.server.start(port);
+                    self.connected = true;
+                }
+            } else {
+                let stop_button = Button::new("Stop");
+                if ui.add(stop_button).clicked() {
+                    self.server.stop();
+                }
+            }
+
+            match &status {
+                GdbServerStatus::Stopped => {}
+                GdbServerStatus::Connecting => {
+                    ui.label("Connecting...");
+                }
+                GdbServerStatus::Running => {
+                    ui.label("Running");
+                }
+                GdbServerStatus::Error(message) => {
+                    ui.label(message);
+                }
+            }
+        });
+    }
+}

src/window/input.rs

@@ -0,0 +1,263 @@
+use egui::{
+    Button, CentralPanel, Context, Label, Layout, TopBottomPanel, Ui, ViewportBuilder, ViewportId,
+};
+use egui_extras::{Column, TableBuilder};
+use gilrs::{EventType, GamepadId};
+use std::sync::RwLock;
+
+use crate::{
+    emulator::{SimId, VBKey},
+    input::{MappingProvider, Mappings},
+};
+
+use super::AppWindow;
+
+pub struct InputWindow {
+    mappings: MappingProvider,
+    now_binding: Option<VBKey>,
+    active_tab: InputTab,
+}
+
+const KEY_NAMES: [(VBKey, &str); 14] = [
+    (VBKey::LU, "Up"),
+    (VBKey::LD, "Down"),
+    (VBKey::LL, "Left"),
+    (VBKey::LR, "Right"),
+    (VBKey::SEL, "Select"),
+    (VBKey::STA, "Start"),
+    (VBKey::B, "B"),
+    (VBKey::A, "A"),
+    (VBKey::LT, "L-Trigger"),
+    (VBKey::RT, "R-Trigger"),
+    (VBKey::RU, "R-Up"),
+    (VBKey::RD, "R-Down"),
+    (VBKey::RL, "R-Left"),
+    (VBKey::RR, "R-Right"),
+];
+
+impl InputWindow {
+    pub fn new(mappings: MappingProvider) -> Self {
+        Self {
+            mappings,
+            now_binding: None,
+            active_tab: InputTab::Player1,
+        }
+    }
+
+    fn show_bindings<T: Mappings>(
+        &mut self,
+        ui: &mut Ui,
+        mappings: &RwLock<T>,
+        bind_message: &str,
+    ) {
+        ui.horizontal(|ui| {
+            if ui.button("Use defaults").clicked() {
+                mappings.write().unwrap().use_default_mappings();
+                self.mappings.save();
+                self.now_binding = None;
+            }
+            if ui.button("Clear all").clicked() {
+                mappings.write().unwrap().clear_all_mappings();
+                self.mappings.save();
+                self.now_binding = None;
+            }
+        });
+        ui.separator();
+        let mut names = {
+            let mapping = mappings.read().unwrap();
+            mapping.mapping_names()
+        };
+        TableBuilder::new(ui)
+            .column(Column::remainder())
+            .column(Column::remainder())
+            .cell_layout(Layout::left_to_right(egui::Align::Center))
+            .body(|mut body| {
+                for keys in KEY_NAMES.chunks_exact(2) {
+                    body.row(20.0, |mut row| {
+                        for (key, name) in keys {
+                            let binding = names.remove(key).map(|mut s| {
+                                s.sort();
+                                s.join(", ")
+                            });
+                            row.col(|ui| {
+                                let size = ui.available_size_before_wrap();
+                                let width = size.x;
+                                let height = size.y;
+                                ui.add_sized((width * 0.2, height), Label::new(*name));
+                                let label_text = if self.now_binding == Some(*key) {
+                                    bind_message
+                                } else {
+                                    binding.as_deref().unwrap_or("")
+                                };
+                                if ui
+                                    .add_sized((width * 0.6, height), Button::new(label_text))
+                                    .clicked()
+                                {
+                                    self.now_binding = Some(*key);
+                                }
+                                if ui
+                                    .add_sized(ui.available_size(), Button::new("Clear"))
+                                    .clicked()
+                                {
+                                    let mut mapping = mappings.write().unwrap();
+                                    mapping.clear_mappings(*key);
+                                    drop(mapping);
+                                    self.mappings.save();
+                                    self.now_binding = None;
+                                }
+                            });
+                        }
+                    });
+                }
+            });
+    }
+
+    fn show_key_bindings(&mut self, ui: &mut Ui, sim_id: SimId) {
+        let mappings = self.mappings.for_sim(sim_id).clone();
+        self.show_bindings(ui, &mappings, "Press any key");
+    }
+
+    fn show_gamepads(&mut self, ui: &mut Ui) {
+        let mut gamepads = self.mappings.gamepad_info();
+        gamepads.sort_by_key(|g| usize::from(g.id));
+
+        if gamepads.is_empty() {
+            ui.label("No gamepads connected.");
+            return;
+        }
+
+        for (index, gamepad) in gamepads.into_iter().enumerate() {
+            ui.horizontal(|ui| {
+                ui.label(format!("Gamepad {index}: {}", gamepad.name));
+                let mut bound_to = gamepad.bound_to;
+                let mut rebind = false;
+                rebind |= ui
+                    .selectable_value(&mut bound_to, Some(SimId::Player1), "Player 1")
+                    .changed();
+                rebind |= ui
+                    .selectable_value(&mut bound_to, Some(SimId::Player2), "Player 2")
+                    .changed();
+                rebind |= ui.selectable_value(&mut bound_to, None, "Nobody").changed();
+                if rebind {
+                    match bound_to {
+                        Some(sim_id) => self.mappings.assign_gamepad(gamepad.id, sim_id),
+                        None => self.mappings.unassign_gamepad(gamepad.id),
+                    }
+                }
+                ui.separator();
+                if ui.button("Rebind").clicked() {
+                    self.active_tab = InputTab::RebindGamepad(gamepad.id);
+                }
+            });
+        }
+    }
+
+    fn show_gamepad_bindings(&mut self, ui: &mut Ui, gamepad_id: GamepadId) {
+        let Some(mappings) = self.mappings.for_gamepad(gamepad_id) else {
+            self.active_tab = InputTab::Gamepads;
+            return;
+        };
+        self.show_bindings(ui, &mappings, "Press any input");
+    }
+}
+
+impl AppWindow for InputWindow {
+    fn viewport_id(&self) -> ViewportId {
+        ViewportId::from_hash_of("input")
+    }
+
+    fn initial_viewport(&self) -> ViewportBuilder {
+        ViewportBuilder::default()
+            .with_title("Bind Inputs")
+            .with_inner_size((600.0, 400.0))
+    }
+
+    fn show(&mut self, ctx: &Context) {
+        TopBottomPanel::top("options").show(ctx, |ui| {
+            ui.horizontal(|ui| {
+                let old_active_tab = self.active_tab;
+                ui.selectable_value(&mut self.active_tab, InputTab::Player1, "Player 1");
+                ui.selectable_value(&mut self.active_tab, InputTab::Player2, "Player 2");
+                ui.selectable_value(&mut self.active_tab, InputTab::Gamepads, "Gamepads");
+                if matches!(self.active_tab, InputTab::RebindGamepad(_)) {
+                    let tab = self.active_tab;
+                    ui.selectable_value(&mut self.active_tab, tab, "Rebind Gamepad");
+                }
+                if old_active_tab != self.active_tab {
+                    self.now_binding = None;
+                }
+            });
+        });
+        CentralPanel::default().show(ctx, |ui| {
+            match self.active_tab {
+                InputTab::Player1 => self.show_key_bindings(ui, SimId::Player1),
+                InputTab::Player2 => self.show_key_bindings(ui, SimId::Player2),
+                InputTab::Gamepads => self.show_gamepads(ui),
+                InputTab::RebindGamepad(id) => self.show_gamepad_bindings(ui, id),
+            };
+        });
+    }
+
+    fn handle_key_event(&mut self, event: &winit::event::KeyEvent) {
+        if !event.state.is_pressed() {
+            return;
+        }
+        let sim_id = match self.active_tab {
+            InputTab::Player1 => SimId::Player1,
+            InputTab::Player2 => SimId::Player2,
+            _ => {
+                return;
+            }
+        };
+        let Some(vb) = self.now_binding.take() else {
+            return;
+        };
+        let mut mappings = self.mappings.for_sim(sim_id).write().unwrap();
+        mappings.add_keyboard_mapping(vb, event.physical_key);
+        drop(mappings);
+        self.mappings.save();
+    }
+
+    fn handle_gamepad_event(&mut self, event: &gilrs::Event) {
+        let InputTab::RebindGamepad(gamepad_id) = self.active_tab else {
+            return;
+        };
+        if gamepad_id != event.id {
+            return;
+        }
+        let Some(mappings) = self.mappings.for_gamepad(gamepad_id) else {
+            return;
+        };
+        let Some(vb) = self.now_binding else {
+            return;
+        };
+        match event.event {
+            EventType::ButtonPressed(_, code) => {
+                let mut mapping = mappings.write().unwrap();
+                mapping.add_button_mapping(vb, code);
+                self.now_binding.take();
+            }
+            EventType::AxisChanged(_, value, code) => {
+                if value < -0.75 {
+                    let mut mapping = mappings.write().unwrap();
+                    mapping.add_axis_neg_mapping(vb, code);
+                    self.now_binding.take();
+                }
+                if value > 0.75 {
+                    let mut mapping = mappings.write().unwrap();
+                    mapping.add_axis_pos_mapping(vb, code);
+                    self.now_binding.take();
+                }
+            }
+            _ => {}
+        }
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum InputTab {
+    Player1,
+    Player2,
+    Gamepads,
+    RebindGamepad(GamepadId),
+}