Update core for good luck

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 +1,35 @@
+[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 = { git = "https://github.com/sidit77/cpal.git", rev = "66ed6be" }
+egui = "0.29"
+egui_extras = "0.29"
+egui-winit = "0.29"
+egui-wgpu = { version = "0.29", features = ["winit"] }
+gilrs = "0.11"
+itertools = "0.13"
+num-derive = "0.4"
+num-traits = "0.2"
+pollster = "0.4"
+rfd = "0.15"
+rtrb = "0.3"
+rubato = "0.16"
+thread-priority = "1"
+wgpu = "22.1"
+winit = "0.30"
+
+[target.'cfg(windows)'.dependencies]
+windows = { version = "0.58", features = ["Win32_System_Threading"] }
+
+[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 +1,14 @@
+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")
+        .define("VB_LITTLE_ENDIAN", None)
+        .define("VB_SIGNED_PROPAGATE", None)
+        .define("VB_DIV_GENERIC", None)
+        .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 +1,368 @@
+use std::{collections::HashSet, num::NonZero, sync::Arc, thread};
+
+use egui::{
+    ahash::{HashMap, HashMapExt},
+    Context, FontData, FontDefinitions, FontFamily, TextWrapMode, ViewportBuilder, ViewportCommand,
+    ViewportId, ViewportInfo,
+};
+use gilrs::{EventType, Gilrs};
+use winit::{
+    application::ApplicationHandler,
+    event::WindowEvent,
+    event_loop::{ActiveEventLoop, EventLoopProxy},
+    window::Window,
+};
+
+use crate::{
+    controller::ControllerManager,
+    emulator::{EmulatorClient, SimId},
+    input::MappingProvider,
+    window::{AppWindow, GameWindow, InputWindow},
+};
+
+pub struct Application {
+    client: EmulatorClient,
+    proxy: EventLoopProxy<UserEvent>,
+    mappings: MappingProvider,
+    controllers: ControllerManager,
+    viewports: HashMap<ViewportId, Viewport>,
+    focused: Option<ViewportId>,
+}
+
+impl Application {
+    pub fn new(client: EmulatorClient, proxy: EventLoopProxy<UserEvent>) -> Self {
+        let mappings = MappingProvider::new();
+        let controllers = ControllerManager::new(client.clone(), &mappings);
+        {
+            let mappings = mappings.clone();
+            let proxy = proxy.clone();
+            thread::spawn(|| process_gamepad_input(mappings, proxy));
+        }
+        Self {
+            client,
+            proxy,
+            mappings,
+            controllers,
+            viewports: HashMap::new(),
+            focused: None,
+        }
+    }
+
+    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, window));
+    }
+}
+
+impl ApplicationHandler<UserEvent> for Application {
+    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
+        let app = GameWindow::new(self.client.clone(), self.proxy.clone(), SimId::Player1);
+        let wrapper = Viewport::new(event_loop, Box::new(app));
+        self.focused = Some(wrapper.id());
+        self.viewports.insert(wrapper.id(), wrapper);
+    }
+
+    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::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(), SimId::Player2);
+                self.open(event_loop, Box::new(p2));
+            }
+        }
+    }
+
+    fn about_to_wait(&mut self, _event_loop: &ActiveEventLoop) {
+        if let Some(viewport) = self.viewports.get(&ViewportId::ROOT) {
+            viewport.window.request_redraw();
+        }
+    }
+}
+
+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, mut app: Box<dyn AppWindow>) -> Self {
+        let mut painter = egui_wgpu::winit::Painter::new(
+            egui_wgpu::WgpuConfiguration::default(),
+            1,
+            None,
+            false,
+            true,
+        );
+
+        let ctx = Context::default();
+        let mut fonts = FontDefinitions::empty();
+        fonts.font_data.insert(
+            "Selawik".into(),
+            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();
+        });
+
+        let mut info = ViewportInfo::default();
+        let builder = app.initial_viewport();
+        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,
+            false,
+        );
+
+        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),
+    OpenInput,
+    OpenPlayer2,
+}
+
+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 Ok(mut gilrs) = Gilrs::new() else {
+        eprintln!("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 +1,103 @@
+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 +1,128 @@
+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 +1,370 @@
+use std::{
+    collections::HashMap,
+    fs,
+    path::{Path, PathBuf},
+    sync::{
+        atomic::{AtomicBool, AtomicUsize, Ordering},
+        mpsc::{self, RecvError, TryRecvError},
+        Arc,
+    },
+};
+
+use anyhow::Result;
+
+use crate::{audio::Audio, graphics::TextureSink};
+pub use shrooms_vb_core::VBKey;
+use shrooms_vb_core::{Sim, EXPECTED_FRAME_SIZE};
+
+mod shrooms_vb_core;
+
+pub struct EmulatorBuilder {
+    rom: Option<PathBuf>,
+    commands: mpsc::Receiver<EmulatorCommand>,
+    sim_count: Arc<AtomicUsize>,
+    running: Arc<[AtomicBool; 2]>,
+    has_game: Arc<[AtomicBool; 2]>,
+    audio_on: Arc<[AtomicBool; 2]>,
+    linked: 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,
+            sim_count: Arc::new(AtomicUsize::new(0)),
+            running: Arc::new([AtomicBool::new(false), AtomicBool::new(false)]),
+            has_game: Arc::new([AtomicBool::new(false), AtomicBool::new(false)]),
+            audio_on: Arc::new([AtomicBool::new(true), AtomicBool::new(true)]),
+            linked: Arc::new(AtomicBool::new(false)),
+        };
+        let client = EmulatorClient {
+            queue,
+            sim_count: builder.sim_count.clone(),
+            running: builder.running.clone(),
+            has_game: builder.has_game.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 build(self) -> Result<Emulator> {
+        let mut emulator = Emulator::new(
+            self.commands,
+            self.sim_count,
+            self.running,
+            self.has_game,
+            self.audio_on,
+            self.linked,
+        )?;
+        if let Some(path) = self.rom {
+            emulator.load_rom(SimId::Player1, &path)?;
+        }
+        Ok(emulator)
+    }
+}
+
+pub struct Emulator {
+    sims: Vec<Sim>,
+    audio: Audio,
+    commands: mpsc::Receiver<EmulatorCommand>,
+    sim_count: Arc<AtomicUsize>,
+    running: Arc<[AtomicBool; 2]>,
+    has_game: Arc<[AtomicBool; 2]>,
+    audio_on: Arc<[AtomicBool; 2]>,
+    linked: Arc<AtomicBool>,
+    renderers: HashMap<SimId, TextureSink>,
+}
+
+impl Emulator {
+    fn new(
+        commands: mpsc::Receiver<EmulatorCommand>,
+        sim_count: Arc<AtomicUsize>,
+        running: Arc<[AtomicBool; 2]>,
+        has_game: Arc<[AtomicBool; 2]>,
+        audio_on: Arc<[AtomicBool; 2]>,
+        linked: Arc<AtomicBool>,
+    ) -> Result<Self> {
+        Ok(Self {
+            sims: vec![],
+            audio: Audio::init()?,
+            commands,
+            sim_count,
+            running,
+            has_game,
+            audio_on,
+            linked,
+            renderers: HashMap::new(),
+        })
+    }
+
+    pub fn load_rom(&mut self, sim_id: SimId, path: &Path) -> Result<()> {
+        let bytes = fs::read(path)?;
+        self.reset_sim(sim_id, Some(bytes))?;
+        Ok(())
+    }
+
+    pub fn start_second_sim(&mut self, rom: Option<PathBuf>) -> Result<()> {
+        let bytes = if let Some(path) = rom {
+            Some(fs::read(path)?)
+        } else {
+            self.sims.first().and_then(|s| s.clone_rom())
+        };
+        self.reset_sim(SimId::Player2, bytes)?;
+        self.link_sims();
+        Ok(())
+    }
+
+    fn reset_sim(&mut self, sim_id: SimId, new_rom: Option<Vec<u8>>) -> Result<()> {
+        let index = sim_id.to_index();
+        while self.sims.len() <= index {
+            self.sims.push(Sim::new());
+        }
+        self.sim_count.store(self.sims.len(), Ordering::Relaxed);
+        let sim = &mut self.sims[index];
+        sim.reset();
+        if let Some(bytes) = new_rom {
+            sim.load_rom(bytes)?;
+            self.has_game[index].store(true, Ordering::Release);
+        }
+        if self.has_game[index].load(Ordering::Acquire) {
+            self.running[index].store(true, Ordering::Release);
+        }
+        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);
+    }
+
+    pub fn stop_second_sim(&mut self) {
+        self.renderers.remove(&SimId::Player2);
+        self.sims.truncate(1);
+        self.sim_count.store(self.sims.len(), Ordering::Relaxed);
+        self.running[SimId::Player2.to_index()].store(false, Ordering::Release);
+        self.has_game[SimId::Player2.to_index()].store(false, Ordering::Release);
+        self.linked.store(false, Ordering::Release);
+    }
+
+    pub fn run(&mut self) {
+        let mut eye_contents = vec![0u8; 384 * 224 * 2];
+        let mut audio_samples = vec![];
+        loop {
+            let p1_running = self.running[SimId::Player1.to_index()].load(Ordering::Acquire);
+            let p2_running = self.running[SimId::Player2.to_index()].load(Ordering::Acquire);
+            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();
+            }
+
+            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 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 weight = if p1_audio && p2_audio { 0.5 } else { 1.0 };
+            if p1_audio {
+                if let Some(sim) = self.sims.get_mut(SimId::Player1.to_index()) {
+                    sim.read_samples(&mut audio_samples, weight);
+                }
+            }
+            if p2_audio {
+                if let Some(sim) = self.sims.get_mut(SimId::Player2.to_index()) {
+                    sim.read_samples(&mut audio_samples, weight);
+                }
+            }
+            if audio_samples.is_empty() {
+                audio_samples.resize(EXPECTED_FRAME_SIZE, 0.0);
+            } else {
+                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(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 => {
+                for sim in SimId::values() {
+                    self.running[sim.to_index()].store(false, Ordering::Release);
+                }
+            }
+            EmulatorCommand::Resume => {
+                for sim_id in SimId::values() {
+                    let index = sim_id.to_index();
+                    if self.has_game[index].load(Ordering::Acquire) {
+                        self.running[index].store(true, Ordering::Relaxed);
+                    }
+                }
+            }
+            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) {
+                    eprintln!("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);
+                }
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum EmulatorCommand {
+    SetRenderer(SimId, TextureSink),
+    LoadGame(SimId, PathBuf),
+    StartSecondSim(Option<PathBuf>),
+    StopSecondSim,
+    Pause,
+    Resume,
+    SetAudioEnabled(bool, bool),
+    Link,
+    Unlink,
+    Reset(SimId),
+    SetKeys(SimId, VBKey),
+}
+
+#[derive(Clone)]
+pub struct EmulatorClient {
+    queue: mpsc::Sender<EmulatorCommand>,
+    sim_count: Arc<AtomicUsize>,
+    running: Arc<[AtomicBool; 2]>,
+    has_game: Arc<[AtomicBool; 2]>,
+    audio_on: Arc<[AtomicBool; 2]>,
+    linked: Arc<AtomicBool>,
+}
+
+impl EmulatorClient {
+    pub fn has_player_2(&self) -> bool {
+        self.sim_count.load(Ordering::Acquire) == 2
+    }
+    pub fn is_running(&self, sim_id: SimId) -> bool {
+        self.running[sim_id.to_index()].load(Ordering::Acquire)
+    }
+    pub fn has_game(&self, sim_id: SimId) -> bool {
+        self.has_game[sim_id.to_index()].load(Ordering::Acquire)
+    }
+    pub fn are_sims_linked(&self) -> bool {
+        self.linked.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 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 +1,298 @@
+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 = "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 = "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 = "vbSetPeer"]
+    fn vb_set_peer(sim: *mut VB, peer: *mut VB);
+    #[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;
+pub const EXPECTED_FRAME_SIZE: usize = 834 * 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 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 {
+        // 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)) };
+
+        // 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/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 +1,344 @@
+use std::{
+    collections::{hash_map::Entry, HashMap},
+    sync::{Arc, RwLock},
+};
+
+use gilrs::{ev::Code, Axis, Button, Gamepad, GamepadId};
+use winit::keyboard::{KeyCode, PhysicalKey};
+
+use crate::emulator::{SimId, VBKey};
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+struct DeviceId(u16, u16);
+
+#[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);
+}
+
+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);
+    }
+}
+
+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);
+    }
+}
+
+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 {
+    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() -> Self {
+        let mut mappings = HashMap::new();
+
+        let mut p1_mappings = InputMapping::default();
+        p1_mappings.use_default_mappings();
+        let p2_mappings = InputMapping::default();
+
+        mappings.insert(SimId::Player1, Arc::new(RwLock::new(p1_mappings)));
+        mappings.insert(SimId::Player2, Arc::new(RwLock::new(p2_mappings)));
+        Self {
+            device_mappings: Arc::new(RwLock::new(HashMap::new())),
+            gamepad_info: Arc::new(RwLock::new(HashMap::new())),
+            sim_mappings: 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;
+        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) {
+            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;
+        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()
+    }
+}

src/main.rs

@@ -0,0 +1,62 @@
+use std::{path::PathBuf, process};
+
+use anyhow::Result;
+use app::Application;
+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;
+mod window;
+
+#[derive(Parser)]
+struct Args {
+    rom: Option<PathBuf>,
+}
+
+#[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<()> {
+    #[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);
+    }
+
+    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 Application::new(client, proxy))?;
+    Ok(())
+}

src/window.rs

@@ -0,0 +1,24 @@
+use egui::{Context, ViewportBuilder, ViewportId};
+pub use game::GameWindow;
+pub use input::InputWindow;
+use winit::event::KeyEvent;
+
+mod game;
+mod game_screen;
+mod input;
+
+pub trait AppWindow {
+    fn viewport_id(&self) -> ViewportId;
+    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/game.rs

@@ -0,0 +1,181 @@
+use crate::{
+    app::UserEvent,
+    emulator::{EmulatorClient, EmulatorCommand, SimId},
+};
+use egui::{
+    menu, Button, CentralPanel, Color32, Context, Frame, Response, TopBottomPanel, Ui,
+    ViewportBuilder, ViewportCommand, ViewportId, WidgetText,
+};
+use winit::event_loop::EventLoopProxy;
+
+use super::{game_screen::GameScreen, AppWindow};
+
+pub struct GameWindow {
+    client: EmulatorClient,
+    proxy: EventLoopProxy<UserEvent>,
+    sim_id: SimId,
+    screen: Option<GameScreen>,
+}
+
+impl GameWindow {
+    pub fn new(client: EmulatorClient, proxy: EventLoopProxy<UserEvent>, sim_id: SimId) -> Self {
+        Self {
+            client,
+            proxy,
+            sim_id,
+            screen: 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(SimId::Player1, path));
+                }
+                ui.close_menu();
+            }
+            if ui.button("Quit").clicked() {
+                ctx.send_viewport_cmd(ViewportCommand::Close);
+            }
+        });
+        ui.menu_button("Emulation", |ui| {
+            let has_game = self.client.has_game(self.sim_id);
+            if self.client.is_running(self.sim_id) {
+                if ui.add_enabled(has_game, Button::new("Pause")).clicked() {
+                    self.client.send_command(EmulatorCommand::Pause);
+                    ui.close_menu();
+                }
+            } else if ui.add_enabled(has_game, Button::new("Resume")).clicked() {
+                self.client.send_command(EmulatorCommand::Resume);
+                ui.close_menu();
+            }
+            if ui.add_enabled(has_game, Button::new("Reset")).clicked() {
+                self.client
+                    .send_command(EmulatorCommand::Reset(self.sim_id));
+                ui.close_menu();
+            }
+        });
+        ui.menu_button("Video", |ui| {
+            let current_dims = ctx.input(|i| i.viewport().inner_rect.unwrap());
+            let current_dims = current_dims.max - current_dims.min;
+
+            for scale in 1..=4 {
+                let label = format!("x{scale}");
+                let scale = scale as f32;
+                let dims = (384.0 * scale, 224.0 * scale + 22.0).into();
+                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("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();
+            }
+        });
+        ui.menu_button("Multiplayer", |ui| {
+            if self.sim_id == SimId::Player1
+                && !self.client.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 self.client.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();
+                }
+            }
+        });
+    }
+}
+
+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 initial_viewport(&self) -> ViewportBuilder {
+        ViewportBuilder::default()
+            .with_title("Shrooms VB")
+            .with_inner_size((384.0, 246.0))
+    }
+
+    fn show(&mut self, ctx: &Context) {
+        TopBottomPanel::top("menubar")
+            .exact_height(22.0)
+            .show(ctx, |ui| {
+                menu::bar(ui, |ui| {
+                    self.show_menu(ctx, 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_ref() {
+                ui.add(screen);
+            }
+        });
+    }
+
+    fn on_init(&mut self, render_state: &egui_wgpu::RenderState) {
+        let (screen, sink) = GameScreen::init(render_state);
+        self.client
+            .send_command(EmulatorCommand::SetRenderer(self.sim_id, sink));
+        self.screen = Some(screen)
+    }
+
+    fn on_destroy(&mut self) {
+        if self.sim_id == SimId::Player2 {
+            self.client.send_command(EmulatorCommand::StopSecondSim);
+        }
+    }
+}
+
+trait UiExt {
+    fn selectable_button(&mut self, selected: bool, text: impl Into<WidgetText>) -> 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)
+    }
+}

src/window/game_screen.rs

@@ -0,0 +1,206 @@
+use std::sync::Arc;
+
+use egui::Widget;
+use wgpu::{util::DeviceExt as _, BindGroup, BindGroupLayout, RenderPipeline};
+
+use crate::graphics::TextureSink;
+
+pub struct GameScreen {
+    bind_group: Arc<BindGroup>,
+}
+
+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!("../anaglyph.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 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::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,
+        });
+
+        render_state
+            .renderer
+            .write()
+            .callback_resources
+            .insert(SharedGameScreenResources {
+                pipeline: render_pipeline,
+                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 {
+            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 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_buf.as_entire_binding(),
+                },
+            ],
+        });
+
+        (
+            Self {
+                bind_group: Arc::new(bind_group),
+            },
+            sink,
+        )
+    }
+}
+
+impl Widget for &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(),
+            },
+        );
+        ui.painter().add(callback);
+        response
+    }
+}
+
+struct GameScreenCallback {
+    bind_group: Arc<BindGroup>,
+}
+
+impl egui_wgpu::CallbackTrait for GameScreenCallback {
+    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 = 384.0 / 224.0;
+        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;
+        render_pass.set_pipeline(&resources.pipeline);
+        render_pass.set_bind_group(0, &self.bind_group, &[]);
+        render_pass.set_viewport(x, y, w, h, 0.0, 1.0);
+        render_pass.draw(0..6, 0..1);
+    }
+}
+
+struct SharedGameScreenResources {
+    pipeline: RenderPipeline,
+    bind_group_layout: BindGroupLayout,
+}
+
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+#[repr(C)]
+struct Colors {
+    left: [f32; 4],
+    right: [f32; 4],
+}

src/window/input.rs

@@ -0,0 +1,257 @@
+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.now_binding = None;
+            }
+            if ui.button("Clear all").clicked() {
+                mappings.write().unwrap().clear_all_mappings();
+                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);
+                                    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);
+    }
+
+    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),
+}