Write textures in separate thread; fixes perf

Reviewed-on: PVB/shrooms-vb-native#1

.gitignore

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

Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "shrooms-vb"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1"
+bitflags = "2"
+bytemuck = { version = "1", features = ["derive"] }
+clap = { version = "4", features = ["derive"] }
+cpal = "0.15"
+imgui = { version = "0.12", features = ["tables-api"] }
+imgui-wgpu = { git = "https://github.com/Yatekii/imgui-wgpu-rs", rev = "2edd348" }
+imgui-winit-support = "0.13"
+itertools = "0.13"
+native-dialog = "0.7"
+num-derive = "0.4"
+num-traits = "0.2"
+pollster = "0.4"
+rtrb = "0.3"
+rubato = "0.16"
+thread-priority = "1"
+wgpu = "22.1"
+winit = "0.30"
+
+[build-dependencies]
+cc = "1"
+
+[profile.release]
+lto = true

README.md

@@ -1,15 +1,15 @@
 # Shrooms VB (native)
 
-An SDL-based implementation of shrooms-vb.
+A native implementation of shrooms-vb. Written in Rust, using winit, wgpu, and Dear ImGui. Should run on any major OS.
 
 ## Setup
 
 Install the following dependencies:
- - `gcc` (or MinGW on Windows) (or whatever, just set `CC`)
+ - `cargo`
- - `pkg-config`
- - sdl2
 
 Run
 ```sh
-make build
+cargo build --release
-```
+```
+
+The executable will be in `target/release/shrooms-vb[.exe]`

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.rs

@@ -0,0 +1,11 @@
+use std::path::Path;
+
+fn main() {
+    println!("cargo::rerun-if-changed=shrooms-vb-core");
+    cc::Build::new()
+        .include(Path::new("shrooms-vb-core/core"))
+        .opt_level(2)
+        .flag_if_supported("-fno-strict-aliasing")
+        .file(Path::new("shrooms-vb-core/core/vb.c"))
+        .compile("vb");
+}

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

src/anaglyph.wgsl

@@ -0,0 +1,55 @@
+// 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_main(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];
+}

src/app.rs

@@ -0,0 +1,142 @@
+use std::{
+    collections::HashMap,
+    fmt::Debug,
+    sync::{Arc, RwLock},
+};
+
+use game::GameWindow;
+use input::InputWindow;
+use winit::{
+    application::ApplicationHandler,
+    event::{Event, WindowEvent},
+    event_loop::{ActiveEventLoop, EventLoopProxy},
+    window::WindowId,
+};
+
+use crate::{
+    controller::ControllerState,
+    emulator::{EmulatorClient, EmulatorCommand, SimId},
+    input::InputMapper,
+};
+
+mod common;
+mod game;
+mod input;
+
+pub struct App {
+    windows: HashMap<WindowId, Box<dyn AppWindow>>,
+    client: EmulatorClient,
+    input_mapper: Arc<RwLock<InputMapper>>,
+    controller: ControllerState,
+    proxy: EventLoopProxy<UserEvent>,
+    player_2_window: Option<WindowId>,
+}
+
+impl App {
+    pub fn new(client: EmulatorClient, proxy: EventLoopProxy<UserEvent>) -> Self {
+        let input_mapper = Arc::new(RwLock::new(InputMapper::new()));
+        let controller = ControllerState::new(input_mapper.clone());
+        Self {
+            windows: HashMap::new(),
+            client,
+            input_mapper,
+            controller,
+            proxy,
+            player_2_window: None,
+        }
+    }
+}
+
+impl ApplicationHandler<UserEvent> for App {
+    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
+        let window = GameWindow::new(
+            event_loop,
+            SimId::Player1,
+            self.client.clone(),
+            self.proxy.clone(),
+        );
+        self.windows.insert(window.id(), Box::new(window));
+    }
+
+    fn window_event(
+        &mut self,
+        event_loop: &ActiveEventLoop,
+        window_id: WindowId,
+        event: WindowEvent,
+    ) {
+        if let WindowEvent::KeyboardInput { event, .. } = &event {
+            if let Some((sim_id, pressed)) = self.controller.key_event(event) {
+                self.client
+                    .send_command(EmulatorCommand::SetKeys(sim_id, pressed));
+            }
+        }
+        let Some(window) = self.windows.get_mut(&window_id) else {
+            return;
+        };
+        window.handle_event(event_loop, &Event::WindowEvent { window_id, event });
+    }
+
+    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: UserEvent) {
+        match event {
+            UserEvent::OpenInputWindow => {
+                let window =
+                    InputWindow::new(event_loop, self.input_mapper.clone(), self.proxy.clone());
+                self.windows.insert(window.id(), Box::new(window));
+            }
+            UserEvent::OpenPlayer2Window => {
+                if self.player_2_window.is_some() {
+                    return;
+                }
+                let window = GameWindow::new(
+                    event_loop,
+                    SimId::Player2,
+                    self.client.clone(),
+                    self.proxy.clone(),
+                );
+                self.player_2_window = Some(window.id());
+                self.windows.insert(window.id(), Box::new(window));
+            }
+            UserEvent::Close(window_id) => {
+                if self.player_2_window == Some(window_id) {
+                    self.player_2_window.take();
+                }
+                self.windows.remove(&window_id);
+            }
+        }
+    }
+
+    fn device_event(
+        &mut self,
+        event_loop: &ActiveEventLoop,
+        device_id: winit::event::DeviceId,
+        event: winit::event::DeviceEvent,
+    ) {
+        for window in self.windows.values_mut() {
+            window.handle_event(
+                event_loop,
+                &Event::DeviceEvent {
+                    device_id,
+                    event: event.clone(),
+                },
+            );
+        }
+    }
+
+    fn about_to_wait(&mut self, event_loop: &ActiveEventLoop) {
+        for window in self.windows.values_mut() {
+            window.handle_event(event_loop, &Event::AboutToWait);
+        }
+    }
+}
+
+pub trait AppWindow {
+    fn id(&self) -> WindowId;
+    fn handle_event(&mut self, event_loop: &ActiveEventLoop, event: &Event<UserEvent>);
+}
+
+#[derive(Debug)]
+pub enum UserEvent {
+    OpenInputWindow,
+    OpenPlayer2Window,
+    Close(WindowId),
+}

src/app/common.rs

@@ -0,0 +1,264 @@
+use std::{
+    ops::{Deref, DerefMut},
+    sync::Arc,
+    time::Instant,
+};
+
+use imgui::{FontSource, MouseCursor, SuspendedContext, WindowToken};
+use imgui_wgpu::{Renderer, RendererConfig};
+use imgui_winit_support::WinitPlatform;
+use pollster::block_on;
+#[cfg(target_os = "windows")]
+use winit::platform::windows::{CornerPreference, WindowAttributesExtWindows as _};
+use winit::{
+    dpi::{LogicalSize, PhysicalSize, Size},
+    event_loop::ActiveEventLoop,
+    window::{Window, WindowAttributes},
+};
+
+pub struct WindowStateBuilder<'a> {
+    event_loop: &'a ActiveEventLoop,
+    attributes: WindowAttributes,
+}
+impl<'a> WindowStateBuilder<'a> {
+    pub fn new(event_loop: &'a ActiveEventLoop) -> Self {
+        let attributes = Window::default_attributes();
+        #[cfg(target_os = "windows")]
+        let attributes = attributes.with_corner_preference(CornerPreference::DoNotRound);
+        Self {
+            event_loop,
+            attributes,
+        }
+    }
+
+    pub fn with_title<T: Into<String>>(self, title: T) -> Self {
+        Self {
+            attributes: self.attributes.with_title(title),
+            ..self
+        }
+    }
+
+    pub fn with_inner_size<S: Into<Size>>(self, size: S) -> Self {
+        Self {
+            attributes: self.attributes.with_inner_size(size),
+            ..self
+        }
+    }
+
+    pub fn build(self) -> WindowState {
+        WindowState::new(self.event_loop, self.attributes)
+    }
+}
+
+#[derive(Debug)]
+pub struct WindowState {
+    pub device: wgpu::Device,
+    pub queue: Arc<wgpu::Queue>,
+    pub window: Arc<Window>,
+    pub surface_desc: wgpu::SurfaceConfiguration,
+    pub surface: wgpu::Surface<'static>,
+    pub hidpi_factor: f64,
+    pub minimized: bool,
+}
+
+impl WindowState {
+    fn new(event_loop: &ActiveEventLoop, attributes: WindowAttributes) -> Self {
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
+            backends: wgpu::Backends::PRIMARY,
+            ..Default::default()
+        });
+
+        let window = Arc::new(event_loop.create_window(attributes).unwrap());
+
+        let size = window.inner_size();
+        let hidpi_factor = window.scale_factor();
+        let surface = instance.create_surface(window.clone()).unwrap();
+
+        let adapter = block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
+            power_preference: wgpu::PowerPreference::HighPerformance,
+            compatible_surface: Some(&surface),
+            force_fallback_adapter: false,
+        }))
+        .unwrap();
+
+        let (device, queue) =
+            block_on(adapter.request_device(&wgpu::DeviceDescriptor::default(), None)).unwrap();
+        let queue = Arc::new(queue);
+
+        // Set up swap chain
+        let surface_desc = wgpu::SurfaceConfiguration {
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
+            format: wgpu::TextureFormat::Bgra8UnormSrgb,
+            width: size.width,
+            height: size.height,
+            present_mode: wgpu::PresentMode::Fifo,
+            desired_maximum_frame_latency: 2,
+            alpha_mode: wgpu::CompositeAlphaMode::Auto,
+            view_formats: vec![wgpu::TextureFormat::Bgra8Unorm],
+        };
+
+        surface.configure(&device, &surface_desc);
+
+        Self {
+            device,
+            queue,
+            window,
+            surface_desc,
+            surface,
+            hidpi_factor,
+            minimized: false,
+        }
+    }
+
+    pub fn logical_size(&self) -> LogicalSize<u32> {
+        PhysicalSize::new(self.surface_desc.width, self.surface_desc.height)
+            .to_logical(self.hidpi_factor)
+    }
+
+    pub fn handle_resize(&mut self, size: &PhysicalSize<u32>) {
+        if size.width > 0 && size.height > 0 {
+            self.minimized = false;
+            self.surface_desc.width = size.width;
+            self.surface_desc.height = size.height;
+            self.surface.configure(&self.device, &self.surface_desc);
+        } else {
+            self.minimized = true;
+        }
+    }
+}
+
+pub struct ImguiState {
+    pub context: ContextGuard,
+    pub platform: WinitPlatform,
+    pub renderer: Renderer,
+    pub clear_color: wgpu::Color,
+    pub last_frame: Instant,
+    pub last_cursor: Option<MouseCursor>,
+}
+impl ImguiState {
+    pub fn new(window: &WindowState) -> Self {
+        let mut context_guard = ContextGuard::new();
+        let mut context = context_guard.lock().unwrap();
+
+        let mut platform = imgui_winit_support::WinitPlatform::new(&mut context);
+        platform.attach_window(
+            context.io_mut(),
+            &window.window,
+            imgui_winit_support::HiDpiMode::Default,
+        );
+        context.set_ini_filename(None);
+
+        let font_size = (16.0 * window.hidpi_factor) as f32;
+        context.io_mut().font_global_scale = (1.0 / window.hidpi_factor) as f32;
+
+        context.fonts().add_font(&[FontSource::TtfData {
+            data: include_bytes!("../../assets/selawk.ttf"),
+            size_pixels: font_size,
+            config: Some(imgui::FontConfig {
+                oversample_h: 1,
+                pixel_snap_h: true,
+                size_pixels: font_size,
+                ..Default::default()
+            }),
+        }]);
+
+        let style = context.style_mut();
+        style.use_light_colors();
+
+        //
+        // Set up dear imgui wgpu renderer
+        //
+        let renderer_config = RendererConfig {
+            texture_format: window.surface_desc.format,
+            ..Default::default()
+        };
+
+        let renderer = Renderer::new(&mut context, &window.device, &window.queue, renderer_config);
+
+        let last_frame = Instant::now();
+        let last_cursor = None;
+
+        drop(context);
+        Self {
+            context: context_guard,
+            platform,
+            renderer,
+            clear_color: wgpu::Color::BLACK,
+            last_frame,
+            last_cursor,
+        }
+    }
+}
+
+pub struct ContextGuard {
+    value: Option<SuspendedContext>,
+}
+
+impl ContextGuard {
+    fn new() -> Self {
+        Self {
+            value: Some(SuspendedContext::create()),
+        }
+    }
+
+    pub fn lock(&mut self) -> Option<ContextLock<'_>> {
+        let sus = self.value.take()?;
+        match sus.activate() {
+            Ok(ctx) => Some(ContextLock {
+                ctx: Some(ctx),
+                holder: self,
+            }),
+            Err(sus) => {
+                self.value = Some(sus);
+                None
+            }
+        }
+    }
+}
+
+pub struct ContextLock<'a> {
+    ctx: Option<imgui::Context>,
+    holder: &'a mut ContextGuard,
+}
+
+impl<'a> Deref for ContextLock<'a> {
+    type Target = imgui::Context;
+    fn deref(&self) -> &Self::Target {
+        self.ctx.as_ref().unwrap()
+    }
+}
+
+impl<'a> DerefMut for ContextLock<'a> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        self.ctx.as_mut().unwrap()
+    }
+}
+
+impl<'a> Drop for ContextLock<'a> {
+    fn drop(&mut self) {
+        self.holder.value = self.ctx.take().map(|c| c.suspend())
+    }
+}
+
+pub trait UiExt {
+    fn fullscreen_window(&self) -> Option<WindowToken<'_>>;
+    fn right_align_text<T: AsRef<str>>(&self, text: T, space: f32);
+}
+
+impl UiExt for imgui::Ui {
+    fn fullscreen_window(&self) -> Option<WindowToken<'_>> {
+        self.window("fullscreen")
+            .position([0.0, 0.0], imgui::Condition::Always)
+            .size(self.io().display_size, imgui::Condition::Always)
+            .flags(imgui::WindowFlags::NO_DECORATION)
+            .begin()
+    }
+
+    fn right_align_text<T: AsRef<str>>(&self, text: T, space: f32) {
+        let width = self.calc_text_size(text.as_ref())[0];
+        let [left, y] = self.cursor_pos();
+        let right = left + space;
+        self.set_cursor_pos([right - width, y]);
+        self.text(text);
+    }
+}

src/app/game.rs

@@ -0,0 +1,383 @@
+use std::time::Instant;
+use wgpu::util::DeviceExt as _;
+use winit::{
+    dpi::LogicalSize,
+    event::{Event, WindowEvent},
+    event_loop::{ActiveEventLoop, EventLoopProxy},
+    window::WindowId,
+};
+
+use crate::{
+    emulator::{EmulatorClient, EmulatorCommand, SimId},
+    graphics::TextureSink,
+};
+
+use super::{
+    common::{ImguiState, WindowState, WindowStateBuilder},
+    AppWindow, UserEvent,
+};
+
+pub struct GameWindow {
+    window: WindowState,
+    imgui: ImguiState,
+    pipeline: wgpu::RenderPipeline,
+    bind_group: wgpu::BindGroup,
+    sim_id: SimId,
+    client: EmulatorClient,
+    proxy: EventLoopProxy<UserEvent>,
+    paused_due_to_minimize: bool,
+}
+
+impl GameWindow {
+    pub fn new(
+        event_loop: &ActiveEventLoop,
+        sim_id: SimId,
+        client: EmulatorClient,
+        proxy: EventLoopProxy<UserEvent>,
+    ) -> Self {
+        let title = if sim_id == SimId::Player2 {
+            "Shrooms VB (Player 2)"
+        } else {
+            "Shrooms VB"
+        };
+        let window = WindowStateBuilder::new(event_loop)
+            .with_title(title)
+            .with_inner_size(LogicalSize::new(384, 244))
+            .build();
+        let device = &window.device;
+
+        let (sink, texture_view) = TextureSink::new(device, window.queue.clone());
+        client.send_command(EmulatorCommand::SetRenderer(sim_id, sink));
+        let sampler = device.create_sampler(&wgpu::SamplerDescriptor::default());
+        let colors = Colors {
+            left: [1.0, 0.0, 0.0, 1.0],
+            right: [0.0, 0.7734375, 0.9375, 1.0],
+        };
+        let color_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("colors"),
+            contents: bytemuck::bytes_of(&colors),
+            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+        });
+        let texture_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 bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label: Some("bind group"),
+            layout: &texture_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_buf.as_entire_binding(),
+                },
+            ],
+        });
+
+        let shader = device.create_shader_module(wgpu::include_wgsl!("../anaglyph.wgsl"));
+        let render_pipeline_layout =
+            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+                label: Some("render pipeline layout"),
+                bind_group_layouts: &[&texture_bind_group_layout],
+                push_constant_ranges: &[],
+            });
+        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+            label: Some("render pipeline"),
+            layout: Some(&render_pipeline_layout),
+            vertex: wgpu::VertexState {
+                module: &shader,
+                entry_point: "vs_main",
+                buffers: &[],
+                compilation_options: wgpu::PipelineCompilationOptions::default(),
+            },
+            fragment: Some(wgpu::FragmentState {
+                module: &shader,
+                entry_point: "fs_main",
+                targets: &[Some(wgpu::ColorTargetState {
+                    format: wgpu::TextureFormat::Bgra8UnormSrgb,
+                    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 imgui = ImguiState::new(&window);
+
+        Self {
+            window,
+            imgui,
+            pipeline: render_pipeline,
+            bind_group,
+            sim_id,
+            client,
+            proxy,
+            paused_due_to_minimize: false,
+        }
+    }
+
+    fn draw(&mut self, event_loop: &ActiveEventLoop) {
+        let window = &mut self.window;
+        let imgui = &mut self.imgui;
+        let mut context = imgui.context.lock().unwrap();
+        let mut new_size = None;
+
+        let now = Instant::now();
+        context.io_mut().update_delta_time(now - imgui.last_frame);
+        imgui.last_frame = now;
+
+        let frame = match window.surface.get_current_texture() {
+            Ok(frame) => frame,
+            Err(e) => {
+                if !self.window.minimized {
+                    eprintln!("dropped frame: {e:?}");
+                }
+                return;
+            }
+        };
+        imgui
+            .platform
+            .prepare_frame(context.io_mut(), &window.window)
+            .expect("Failed to prepare frame");
+        let ui = context.new_frame();
+        let mut menu_height = 0.0;
+        ui.main_menu_bar(|| {
+            menu_height = ui.window_size()[1];
+            ui.menu("ROM", || {
+                if ui.menu_item("Open ROM") {
+                    let rom = native_dialog::FileDialog::new()
+                        .add_filter("Virtual Boy ROMs", &["vb", "vbrom"])
+                        .show_open_single_file()
+                        .unwrap();
+                    if let Some(path) = rom {
+                        self.client
+                            .send_command(EmulatorCommand::LoadGame(self.sim_id, path));
+                    }
+                }
+                if ui.menu_item("Quit") {
+                    event_loop.exit();
+                }
+            });
+            ui.menu("Emulation", || {
+                let has_game = self.client.has_game();
+                if self.client.is_running() {
+                    if ui.menu_item_config("Pause").enabled(has_game).build() {
+                        self.client.send_command(EmulatorCommand::Pause);
+                    }
+                } else if ui.menu_item_config("Resume").enabled(has_game).build() {
+                    self.client.send_command(EmulatorCommand::Resume);
+                }
+                if ui.menu_item_config("Reset").enabled(has_game).build() {
+                    self.client.send_command(EmulatorCommand::Reset);
+                }
+            });
+            ui.menu("Video", || {
+                let current_dims = window.logical_size();
+                for scale in 1..=4 {
+                    let label = format!("x{scale}");
+                    let dims = LogicalSize::new(384 * scale, 224 * scale + 20);
+                    let selected = dims == current_dims;
+                    if ui.menu_item_config(label).selected(selected).build() {
+                        if let Some(size) = window.window.request_inner_size(dims) {
+                            window.handle_resize(&size);
+                            new_size = Some(size);
+                        }
+                    }
+                }
+            });
+            ui.menu("Input", || {
+                if ui.menu_item("Bind Inputs") {
+                    self.proxy.send_event(UserEvent::OpenInputWindow).unwrap();
+                }
+            });
+            ui.menu("Multiplayer", || {
+                if self.sim_id == SimId::Player1 && ui.menu_item("Open Player 2") {
+                    self.client
+                        .send_command(EmulatorCommand::StartSecondSim(None));
+                    self.proxy.send_event(UserEvent::OpenPlayer2Window).unwrap();
+                }
+            });
+        });
+
+        let mut encoder: wgpu::CommandEncoder = window
+            .device
+            .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
+
+        if imgui.last_cursor != ui.mouse_cursor() {
+            imgui.last_cursor = ui.mouse_cursor();
+            imgui.platform.prepare_render(ui, &window.window);
+        }
+
+        let view = frame
+            .texture
+            .create_view(&wgpu::TextureViewDescriptor::default());
+        let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: None,
+            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                view: &view,
+                resolve_target: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Clear(imgui.clear_color),
+                    store: wgpu::StoreOp::Store,
+                },
+            })],
+            depth_stencil_attachment: None,
+            timestamp_writes: None,
+            occlusion_query_set: None,
+        });
+
+        // Draw the game
+        rpass.set_pipeline(&self.pipeline);
+        let window_width = window.surface_desc.width as f32;
+        let window_height = window.surface_desc.height as f32;
+        let menu_height = menu_height * window.hidpi_factor as f32;
+        let ((x, y), (width, height)) =
+            compute_game_bounds(window_width, window_height, menu_height);
+        rpass.set_viewport(x, y, width, height, 0.0, 1.0);
+        rpass.set_bind_group(0, &self.bind_group, &[]);
+        rpass.draw(0..6, 0..1);
+
+        // Draw the menu on top of the game
+        rpass.set_viewport(0.0, 0.0, window_width, window_height, 0.0, 1.0);
+        imgui
+            .renderer
+            .render(context.render(), &window.queue, &window.device, &mut rpass)
+            .expect("Rendering failed");
+
+        drop(rpass);
+
+        if let Some(size) = new_size {
+            imgui.platform.handle_event::<UserEvent>(
+                context.io_mut(),
+                &window.window,
+                &Event::WindowEvent {
+                    window_id: window.window.id(),
+                    event: WindowEvent::Resized(size),
+                },
+            );
+        }
+
+        window.queue.submit(Some(encoder.finish()));
+
+        frame.present();
+    }
+}
+
+impl AppWindow for GameWindow {
+    fn id(&self) -> WindowId {
+        self.window.window.id()
+    }
+
+    fn handle_event(&mut self, event_loop: &ActiveEventLoop, event: &Event<UserEvent>) {
+        match event {
+            Event::WindowEvent { event, .. } => match event {
+                WindowEvent::Resized(size) => {
+                    self.window.handle_resize(size);
+                    if self.window.minimized {
+                        if self.client.is_running() {
+                            self.client.send_command(EmulatorCommand::Pause);
+                            self.paused_due_to_minimize = true;
+                        }
+                    } else if self.paused_due_to_minimize {
+                        self.client.send_command(EmulatorCommand::Resume);
+                        self.paused_due_to_minimize = false;
+                    }
+                }
+                WindowEvent::CloseRequested => {
+                    if self.sim_id == SimId::Player2 {
+                        self.client.send_command(EmulatorCommand::StopSecondSim);
+                        self.proxy.send_event(UserEvent::Close(self.id())).unwrap();
+                    } else {
+                        event_loop.exit();
+                    }
+                }
+                WindowEvent::RedrawRequested => self.draw(event_loop),
+                _ => (),
+            },
+            Event::AboutToWait => {
+                self.window.window.request_redraw();
+            }
+            _ => (),
+        }
+        let window = &self.window;
+        let imgui = &mut self.imgui;
+        let mut context = imgui.context.lock().unwrap();
+        imgui
+            .platform
+            .handle_event(context.io_mut(), &window.window, event);
+    }
+}
+
+fn compute_game_bounds(
+    window_width: f32,
+    window_height: f32,
+    menu_height: f32,
+) -> ((f32, f32), (f32, f32)) {
+    let available_width = window_width;
+    let available_height = window_height - menu_height;
+
+    let width = available_width.min(available_height * 384.0 / 224.0);
+    let height = available_height.min(available_width * 224.0 / 384.0);
+    let x = (available_width - width) / 2.0;
+    let y = menu_height + (available_height - height) / 2.0;
+    ((x, y), (width, height))
+}
+
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+#[repr(C)]
+struct Colors {
+    left: [f32; 4],
+    right: [f32; 4],
+}

src/app/input.rs

@@ -0,0 +1,222 @@
+use std::{
+    sync::{Arc, RwLock},
+    time::Instant,
+};
+
+use winit::{
+    dpi::LogicalSize,
+    event::{Event, KeyEvent, WindowEvent},
+    event_loop::{ActiveEventLoop, EventLoopProxy},
+};
+
+use crate::{
+    emulator::{SimId, VBKey},
+    input::InputMapper,
+};
+
+use super::{
+    common::{ImguiState, UiExt, WindowState, WindowStateBuilder},
+    AppWindow, UserEvent,
+};
+
+pub struct InputWindow {
+    window: WindowState,
+    imgui: ImguiState,
+    input_mapper: Arc<RwLock<InputMapper>>,
+    proxy: EventLoopProxy<UserEvent>,
+    now_binding: Option<(SimId, VBKey)>,
+}
+
+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(
+        event_loop: &ActiveEventLoop,
+        input_mapper: Arc<RwLock<InputMapper>>,
+        proxy: EventLoopProxy<UserEvent>,
+    ) -> Self {
+        let window = WindowStateBuilder::new(event_loop)
+            .with_title("Bind Inputs")
+            .with_inner_size(LogicalSize::new(600, 400))
+            .build();
+        let imgui = ImguiState::new(&window);
+        Self {
+            window,
+            imgui,
+            input_mapper,
+            now_binding: None,
+            proxy,
+        }
+    }
+
+    fn draw(&mut self) {
+        let window = &mut self.window;
+        let imgui = &mut self.imgui;
+        let mut context = imgui.context.lock().unwrap();
+
+        let now = Instant::now();
+        context.io_mut().update_delta_time(now - imgui.last_frame);
+        imgui.last_frame = now;
+
+        let frame = match window.surface.get_current_texture() {
+            Ok(frame) => frame,
+            Err(e) => {
+                if !self.window.minimized {
+                    eprintln!("dropped frame: {e:?}");
+                }
+                return;
+            }
+        };
+        imgui
+            .platform
+            .prepare_frame(context.io_mut(), &window.window)
+            .expect("Failed to prepare frame");
+        let ui = context.new_frame();
+
+        let mut render_key_bindings = |sim_id: SimId| {
+            if let Some(table) = ui.begin_table("controls", 2) {
+                let binding_names = {
+                    let mapper = self.input_mapper.read().unwrap();
+                    mapper.binding_names(&sim_id)
+                };
+                ui.table_next_row();
+
+                for (key, name) in KEY_NAMES {
+                    let binding = binding_names.get(&key).map(|s| s.as_str());
+                    ui.table_next_column();
+                    let [space, _] = ui.content_region_avail();
+                    ui.group(|| {
+                        ui.right_align_text(name, space * 0.20);
+                        ui.same_line();
+                        let label_text = if self.now_binding == Some((sim_id, key)) {
+                            "Press any input"
+                        } else {
+                            binding.unwrap_or("")
+                        };
+                        let label = format!("{}##{}", label_text, name);
+                        if ui.button_with_size(label, [space * 0.60, 0.0]) {
+                            self.now_binding = Some((sim_id, key));
+                        }
+                    });
+                    ui.same_line();
+                    if ui.button(format!("Clear##{name}")) {
+                        let mut mapper = self.input_mapper.write().unwrap();
+                        mapper.clear_binding(sim_id, key);
+                    }
+                }
+
+                table.end();
+            }
+        };
+
+        if let Some(window) = ui.fullscreen_window() {
+            if let Some(tabs) = ui.tab_bar("tabs") {
+                if let Some(tab) = ui.tab_item("Player 1") {
+                    render_key_bindings(SimId::Player1);
+                    tab.end();
+                }
+                if let Some(tab) = ui.tab_item("Player 2") {
+                    render_key_bindings(SimId::Player2);
+                    tab.end();
+                }
+                tabs.end();
+            }
+            window.end();
+        }
+        let mut encoder: wgpu::CommandEncoder = window
+            .device
+            .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
+
+        if imgui.last_cursor != ui.mouse_cursor() {
+            imgui.last_cursor = ui.mouse_cursor();
+            imgui.platform.prepare_render(ui, &window.window);
+        }
+
+        let view = frame
+            .texture
+            .create_view(&wgpu::TextureViewDescriptor::default());
+        let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: None,
+            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                view: &view,
+                resolve_target: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Clear(imgui.clear_color),
+                    store: wgpu::StoreOp::Store,
+                },
+            })],
+            depth_stencil_attachment: None,
+            timestamp_writes: None,
+            occlusion_query_set: None,
+        });
+
+        // Draw the game
+        imgui
+            .renderer
+            .render(context.render(), &window.queue, &window.device, &mut rpass)
+            .expect("Rendering failed");
+
+        drop(rpass);
+
+        window.queue.submit(Some(encoder.finish()));
+
+        frame.present();
+    }
+
+    fn try_bind_key(&mut self, event: &KeyEvent) {
+        if !event.state.is_pressed() {
+            return;
+        }
+        let Some((sim_id, vb)) = self.now_binding.take() else {
+            return;
+        };
+        let mut mapper = self.input_mapper.write().unwrap();
+        mapper.bind_key(sim_id, vb, event.physical_key);
+    }
+}
+
+impl AppWindow for InputWindow {
+    fn id(&self) -> winit::window::WindowId {
+        self.window.window.id()
+    }
+
+    fn handle_event(&mut self, _: &ActiveEventLoop, event: &Event<UserEvent>) {
+        match event {
+            Event::WindowEvent { event, .. } => match event {
+                WindowEvent::Resized(size) => self.window.handle_resize(size),
+                WindowEvent::CloseRequested => {
+                    self.proxy.send_event(UserEvent::Close(self.id())).unwrap()
+                }
+                WindowEvent::KeyboardInput { event, .. } => self.try_bind_key(event),
+                WindowEvent::RedrawRequested => self.draw(),
+                _ => (),
+            },
+            Event::AboutToWait => {
+                self.window.window.request_redraw();
+            }
+            _ => (),
+        }
+
+        let window = &self.window;
+        let imgui = &mut self.imgui;
+        let mut context = imgui.context.lock().unwrap();
+        imgui
+            .platform
+            .handle_event(context.io_mut(), &window.window, event);
+    }
+}

src/audio.rs

@@ -0,0 +1,103 @@
+use std::time::Duration;
+
+use anyhow::{bail, Result};
+use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
+use itertools::Itertools;
+use rubato::{FftFixedInOut, Resampler};
+
+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 |err| eprintln!("stream error: {err}"),
+            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 +1,48 @@
+use std::sync::{Arc, RwLock};
+
+use winit::event::{ElementState, KeyEvent};
+
+use crate::{
+    emulator::{SimId, VBKey},
+    input::InputMapper,
+};
+
+pub struct ControllerState {
+    input_mapper: Arc<RwLock<InputMapper>>,
+    pressed: Vec<VBKey>,
+}
+
+impl ControllerState {
+    pub fn new(input_mapper: Arc<RwLock<InputMapper>>) -> Self {
+        Self {
+            input_mapper,
+            pressed: vec![VBKey::SGN; 2],
+        }
+    }
+
+    pub fn key_event(&mut self, event: &KeyEvent) -> Option<(SimId, VBKey)> {
+        let (sim_id, input) = self.key_event_to_input(event)?;
+        let pressed = &mut self.pressed[sim_id.to_index()];
+        match event.state {
+            ElementState::Pressed => {
+                if pressed.contains(input) {
+                    return None;
+                }
+                pressed.insert(input);
+                Some((sim_id, *pressed))
+            }
+            ElementState::Released => {
+                if !pressed.contains(input) {
+                    return None;
+                }
+                pressed.remove(input);
+                Some((sim_id, *pressed))
+            }
+        }
+    }
+
+    fn key_event_to_input(&self, event: &KeyEvent) -> Option<(SimId, VBKey)> {
+        let mapper = self.input_mapper.read().unwrap();
+        mapper.key_event(event)
+    }
+}

src/emulator.rs

@@ -0,0 +1,270 @@
+use std::{
+    collections::HashMap,
+    fs,
+    path::{Path, PathBuf},
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        mpsc::{self, RecvError, TryRecvError},
+        Arc,
+    },
+};
+
+use anyhow::Result;
+
+use crate::{audio::Audio, graphics::TextureSink};
+use shrooms_vb_core::Sim;
+pub use shrooms_vb_core::VBKey;
+
+mod shrooms_vb_core;
+
+pub struct EmulatorBuilder {
+    rom: Option<PathBuf>,
+    commands: mpsc::Receiver<EmulatorCommand>,
+    running: Arc<AtomicBool>,
+    has_game: Arc<AtomicBool>,
+}
+
+#[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 EmulatorBuilder {
+    pub fn new() -> (Self, EmulatorClient) {
+        let (queue, commands) = mpsc::channel();
+        let builder = Self {
+            rom: None,
+            commands,
+            running: Arc::new(AtomicBool::new(false)),
+            has_game: Arc::new(AtomicBool::new(false)),
+        };
+        let client = EmulatorClient {
+            queue,
+            running: builder.running.clone(),
+            has_game: builder.has_game.clone(),
+        };
+        (builder, client)
+    }
+
+    pub fn with_rom(self, path: &Path) -> Self {
+        Self {
+            rom: Some(path.into()),
+            ..self
+        }
+    }
+
+    pub fn build(self) -> Result<Emulator> {
+        let mut emulator = Emulator::new(self.commands, self.running, self.has_game)?;
+        if let Some(path) = self.rom {
+            emulator.load_rom_from_file(SimId::Player1, &path)?;
+        }
+        Ok(emulator)
+    }
+}
+
+pub struct Emulator {
+    sims: Vec<Sim>,
+    audio: Audio,
+    commands: mpsc::Receiver<EmulatorCommand>,
+    renderers: HashMap<SimId, TextureSink>,
+    running: Arc<AtomicBool>,
+    has_game: Arc<AtomicBool>,
+}
+
+impl Emulator {
+    fn new(
+        commands: mpsc::Receiver<EmulatorCommand>,
+        running: Arc<AtomicBool>,
+        has_game: Arc<AtomicBool>,
+    ) -> Result<Self> {
+        Ok(Self {
+            sims: vec![],
+            audio: Audio::init()?,
+            commands,
+            renderers: HashMap::new(),
+            running,
+            has_game,
+        })
+    }
+
+    pub fn load_rom_from_file(&mut self, sim_id: SimId, path: &Path) -> Result<()> {
+        let bytes = fs::read(path)?;
+        self.load_rom(sim_id, bytes)?;
+        Ok(())
+    }
+
+    pub fn start_second_sim(&mut self, rom: Option<PathBuf>) -> Result<()> {
+        let bytes = if let Some(path) = rom {
+            fs::read(path)?
+        } else if let Some(rom) = self.sims.first().and_then(|s| s.clone_rom()) {
+            rom
+        } else {
+            return Ok(());
+        };
+        self.load_rom(SimId::Player2, bytes)?;
+        Ok(())
+    }
+
+    fn load_rom(&mut self, sim_id: SimId, bytes: Vec<u8>) -> Result<()> {
+        while self.sims.len() <= sim_id.to_index() {
+            self.sims.push(Sim::new());
+        }
+        let sim = &mut self.sims[sim_id.to_index()];
+        sim.reset();
+        sim.load_rom(bytes)?;
+        self.has_game.store(true, Ordering::Release);
+        self.running.store(true, Ordering::Release);
+        Ok(())
+    }
+
+    pub fn stop_second_sim(&mut self) {
+        self.renderers.remove(&SimId::Player2);
+        self.sims.truncate(1);
+    }
+
+    pub fn run(&mut self) {
+        let mut eye_contents = vec![0u8; 384 * 224 * 2];
+        let mut audio_samples = vec![];
+        loop {
+            let mut idle = true;
+            if self.running.load(Ordering::Acquire) {
+                idle = false;
+                Sim::emulate_many(&mut self.sims);
+            }
+            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 eye_contents) {
+                    idle = false;
+                    if renderer.queue_render(&eye_contents).is_err() {
+                        self.renderers.remove(&sim_id);
+                    }
+                }
+            }
+            let weight = 1.0 / self.sims.len() as f32;
+            for sim in self.sims.iter_mut() {
+                sim.read_samples(&mut audio_samples, weight);
+            }
+            if !audio_samples.is_empty() {
+                idle = false;
+                self.audio.update(&audio_samples);
+                audio_samples.clear();
+            }
+            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;
+                    }
+                }
+            }
+        }
+    }
+
+    fn handle_command(&mut self, command: EmulatorCommand) {
+        match command {
+            EmulatorCommand::SetRenderer(sim_id, renderer) => {
+                self.renderers.insert(sim_id, renderer);
+            }
+            EmulatorCommand::LoadGame(sim_id, path) => {
+                if let Err(error) = self.load_rom_from_file(sim_id, &path) {
+                    eprintln!("error loading rom: {}", error);
+                }
+            }
+            EmulatorCommand::StartSecondSim(path) => {
+                if let Err(error) = self.start_second_sim(path) {
+                    eprintln!("error starting second sim: {}", error);
+                }
+            }
+            EmulatorCommand::StopSecondSim => {
+                self.stop_second_sim();
+            }
+            EmulatorCommand::Pause => {
+                self.running.store(false, Ordering::Release);
+            }
+            EmulatorCommand::Resume => {
+                if self.has_game.load(Ordering::Acquire) {
+                    self.running.store(true, Ordering::Relaxed);
+                }
+            }
+            EmulatorCommand::Reset => {
+                for sim in self.sims.iter_mut() {
+                    sim.reset();
+                }
+                if !self.sims.is_empty() {
+                    self.running.store(true, Ordering::Release);
+                }
+            }
+            EmulatorCommand::SetKeys(sim_id, keys) => {
+                if let Some(sim) = self.sims.get_mut(sim_id.to_index()) {
+                    sim.set_keys(keys);
+                }
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum EmulatorCommand {
+    SetRenderer(SimId, TextureSink),
+    LoadGame(SimId, PathBuf),
+    StartSecondSim(Option<PathBuf>),
+    StopSecondSim,
+    Pause,
+    Resume,
+    Reset,
+    SetKeys(SimId, VBKey),
+}
+
+#[derive(Clone)]
+pub struct EmulatorClient {
+    queue: mpsc::Sender<EmulatorCommand>,
+    running: Arc<AtomicBool>,
+    has_game: Arc<AtomicBool>,
+}
+
+impl EmulatorClient {
+    pub fn is_running(&self) -> bool {
+        self.running.load(Ordering::Acquire)
+    }
+    pub fn has_game(&self) -> bool {
+        self.has_game.load(Ordering::Acquire)
+    }
+    pub fn send_command(&self, command: EmulatorCommand) {
+        if let Err(err) = self.queue.send(command) {
+            eprintln!(
+                "could not send command {:?} as emulator is shut down",
+                err.0
+            );
+        }
+    }
+}

src/emulator/shrooms_vb_core.rs

@@ -0,0 +1,277 @@
+use std::{ffi::c_void, ptr, slice};
+
+use anyhow::{anyhow, Result};
+use bitflags::bitflags;
+use num_derive::{FromPrimitive, ToPrimitive};
+
+#[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)]
+    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;
+    }
+}
+
+type OnFrame = extern "C" fn(sim: *mut VB) -> c_int;
+
+#[link(name = "vb")]
+extern "C" {
+    #[link_name = "vbEmulateEx"]
+    fn vb_emulate_ex(sims: *mut *mut VB, count: c_uint, cycles: *mut u32) -> c_int;
+    #[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 = "vbGetSamples"]
+    fn vb_get_samples(
+        sim: *mut VB,
+        typ_: *mut VBDataType,
+        capacity: *mut c_uint,
+        position: *mut c_uint,
+    ) -> *mut c_void;
+    #[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 = "vbReset"]
+    fn vb_reset(sim: *mut VB);
+    #[link_name = "vbSetCartROM"]
+    fn vb_set_cart_rom(sim: *mut VB, rom: *mut c_void, size: u32) -> c_int;
+    #[link_name = "vbSetFrameCallback"]
+    fn vb_set_frame_callback(sim: *mut VB, on_frame: 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 = "vbSetSamples"]
+    fn vb_set_samples(
+        sim: *mut VB,
+        samples: *mut c_void,
+        typ_: VBDataType,
+        capacity: c_uint,
+    ) -> c_int;
+    #[link_name = "vbSetUserData"]
+    fn vb_set_user_data(sim: *mut VB, tag: *mut c_void);
+    #[link_name = "vbSizeOf"]
+    fn vb_size_of() -> usize;
+}
+
+extern "C" fn on_frame(sim: *mut VB) -> i32 {
+    // 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
+}
+
+const AUDIO_CAPACITY_SAMPLES: usize = 834 * 4;
+const AUDIO_CAPACITY_FLOATS: usize = AUDIO_CAPACITY_SAMPLES * 2;
+
+struct VBState {
+    frame_seen: bool,
+}
+
+#[repr(transparent)]
+pub struct Sim {
+    sim: *mut VB,
+}
+
+// SAFETY: the memory pointed to by sim is valid
+unsafe impl Send for Sim {}
+
+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) };
+        unsafe { vb_set_option(sim, VBOption::PseudoHalt, 1) };
+        unsafe { vb_reset(sim) };
+
+        // set up userdata
+        let state = VBState { frame_seen: false };
+        unsafe { vb_set_user_data(sim, Box::into_raw(Box::new(state)).cast()) };
+        unsafe { vb_set_frame_callback(sim, 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_rom(&mut self, rom: Vec<u8>) -> Result<()> {
+        self.unload_rom();
+
+        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 {
+            Ok(())
+        } else {
+            let _: Vec<u8> =
+                unsafe { Vec::from_raw_parts(rom.cast(), size as usize, size as usize) };
+            Err(anyhow!("Invalid ROM size of {} bytes", size))
+        }
+    }
+
+    pub fn clone_rom(&self) -> Option<Vec<u8>> {
+        let mut size = 0;
+        let rom = unsafe { vb_get_cart_rom(self.sim, &mut size) };
+        if rom.is_null() {
+            return None;
+        }
+        // SAFETY: rom definitely points to a valid array of `size` bytes
+        let slice: &[u8] = unsafe { slice::from_raw_parts(rom.cast(), size as usize) };
+        Some(slice.to_vec())
+    }
+
+    fn unload_rom(&mut self) -> Option<Vec<u8>> {
+        let mut size = 0;
+        let rom = unsafe { vb_get_cart_rom(self.sim, &mut size) };
+        if rom.is_null() {
+            return None;
+        }
+        unsafe { vb_set_cart_rom(self.sim, ptr::null_mut(), 0) };
+        let vec = unsafe { Vec::from_raw_parts(rom.cast(), size as usize, size as usize) };
+        Some(vec)
+    }
+
+    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 {
+        // 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(self.sim).cast() };
+        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()) };
+    }
+}
+
+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)) };
+
+        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/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 +1,88 @@
+use std::collections::HashMap;
+
+use winit::{
+    event::KeyEvent,
+    keyboard::{KeyCode, PhysicalKey},
+};
+
+use crate::emulator::{SimId, VBKey};
+
+pub struct InputMapper {
+    vb_bindings: HashMap<SimId, HashMap<VBKey, PhysicalKey>>,
+    key_bindings: HashMap<PhysicalKey, (SimId, VBKey)>,
+}
+
+impl InputMapper {
+    pub fn new() -> Self {
+        let mut mapper = Self {
+            vb_bindings: HashMap::new(),
+            key_bindings: HashMap::new(),
+        };
+        mapper.bind_key(SimId::Player1, VBKey::SEL, PhysicalKey::Code(KeyCode::KeyA));
+        mapper.bind_key(SimId::Player1, VBKey::STA, PhysicalKey::Code(KeyCode::KeyS));
+        mapper.bind_key(SimId::Player1, VBKey::B, PhysicalKey::Code(KeyCode::KeyD));
+        mapper.bind_key(SimId::Player1, VBKey::A, PhysicalKey::Code(KeyCode::KeyF));
+        mapper.bind_key(SimId::Player1, VBKey::LT, PhysicalKey::Code(KeyCode::KeyE));
+        mapper.bind_key(SimId::Player1, VBKey::RT, PhysicalKey::Code(KeyCode::KeyR));
+        mapper.bind_key(SimId::Player1, VBKey::RU, PhysicalKey::Code(KeyCode::KeyI));
+        mapper.bind_key(SimId::Player1, VBKey::RL, PhysicalKey::Code(KeyCode::KeyJ));
+        mapper.bind_key(SimId::Player1, VBKey::RD, PhysicalKey::Code(KeyCode::KeyK));
+        mapper.bind_key(SimId::Player1, VBKey::RR, PhysicalKey::Code(KeyCode::KeyL));
+        mapper.bind_key(
+            SimId::Player1,
+            VBKey::LU,
+            PhysicalKey::Code(KeyCode::ArrowUp),
+        );
+        mapper.bind_key(
+            SimId::Player1,
+            VBKey::LL,
+            PhysicalKey::Code(KeyCode::ArrowLeft),
+        );
+        mapper.bind_key(
+            SimId::Player1,
+            VBKey::LD,
+            PhysicalKey::Code(KeyCode::ArrowDown),
+        );
+        mapper.bind_key(
+            SimId::Player1,
+            VBKey::LR,
+            PhysicalKey::Code(KeyCode::ArrowRight),
+        );
+        mapper
+    }
+
+    pub fn binding_names(&self, sim_id: &SimId) -> HashMap<VBKey, String> {
+        let Some(bindings) = self.vb_bindings.get(sim_id) else {
+            return HashMap::new();
+        };
+        bindings
+            .iter()
+            .map(|(k, v)| {
+                let name = match v {
+                    PhysicalKey::Code(code) => format!("{code:?}"),
+                    k => format!("{:?}", k),
+                };
+                (*k, name)
+            })
+            .collect()
+    }
+
+    pub fn bind_key(&mut self, sim_id: SimId, vb: VBKey, key: PhysicalKey) {
+        let vb_bindings = self.vb_bindings.entry(sim_id).or_default();
+        if let Some(old) = vb_bindings.insert(vb, key) {
+            self.key_bindings.remove(&old);
+        }
+        self.key_bindings.insert(key, (sim_id, vb));
+    }
+
+    pub fn clear_binding(&mut self, sim_id: SimId, vb: VBKey) {
+        let vb_bindings = self.vb_bindings.entry(sim_id).or_default();
+        if let Some(old) = vb_bindings.remove(&vb) {
+            self.key_bindings.remove(&old);
+        }
+    }
+
+    pub fn key_event(&self, event: &KeyEvent) -> Option<(SimId, VBKey)> {
+        self.key_bindings.get(&event.physical_key).copied()
+    }
+}

src/main.rs

@@ -0,0 +1,49 @@
+use std::{path::PathBuf, process};
+
+use anyhow::Result;
+use app::App;
+use clap::Parser;
+use emulator::EmulatorBuilder;
+use thread_priority::{ThreadBuilder, ThreadPriority};
+use winit::event_loop::{ControlFlow, EventLoop};
+
+mod app;
+mod audio;
+mod controller;
+mod emulator;
+mod graphics;
+mod input;
+
+#[derive(Parser)]
+struct Args {
+    rom: Option<PathBuf>,
+}
+
+fn main() -> Result<()> {
+    let args = Args::parse();
+
+    let (mut builder, client) = EmulatorBuilder::new();
+    if let Some(path) = args.rom {
+        builder = builder.with_rom(&path);
+    }
+
+    ThreadBuilder::default()
+        .name("Emulator".to_owned())
+        .priority(ThreadPriority::Max)
+        .spawn_careless(move || {
+            let mut emulator = match builder.build() {
+                Ok(e) => e,
+                Err(err) => {
+                    eprintln!("Error initializing emulator: {err}");
+                    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 App::new(client, proxy))?;
+    Ok(())
+}