src/app.rs

@@ -18,8 +18,8 @@ use crate::{
     controller::ControllerManager,
     emulator::{EmulatorClient, EmulatorCommand, SimId},
     input::MappingProvider,
+    memory::MemoryMonitor,
     persistence::Persistence,
-    vram::VramLoader,
     window::{
         AboutWindow, AppWindow, BgMapWindow, CharacterDataWindow, GameWindow, GdbServerWindow,
         InputWindow,
@@ -40,11 +40,11 @@ fn load_icon() -> anyhow::Result<IconData> {
 pub struct Application {
     icon: Option<Arc<IconData>>,
     wgpu: WgpuState,
-    vram: Arc<VramLoader>,
     client: EmulatorClient,
     proxy: EventLoopProxy<UserEvent>,
     mappings: MappingProvider,
     controllers: ControllerManager,
+    memory: MemoryMonitor,
     persistence: Persistence,
     viewports: HashMap<ViewportId, Viewport>,
     focused: Option<ViewportId>,
@@ -62,6 +62,7 @@ impl Application {
         let persistence = Persistence::new();
         let mappings = MappingProvider::new(persistence.clone());
         let controllers = ControllerManager::new(client.clone(), &mappings);
+        let memory = MemoryMonitor::new(client.clone());
         {
             let mappings = mappings.clone();
             let proxy = proxy.clone();
@@ -70,10 +71,10 @@ impl Application {
         Self {
             icon,
             wgpu,
-            vram: Arc::new(VramLoader::new(client.clone())),
             client,
             proxy,
             mappings,
+            memory,
             controllers,
             persistence,
             viewports: HashMap::new(),
@@ -89,13 +90,7 @@ impl Application {
         }
         self.viewports.insert(
             viewport_id,
-            Viewport::new(
-                event_loop,
-                &self.wgpu,
-                self.icon.clone(),
-                self.vram.clone(),
-                window,
-            ),
+            Viewport::new(event_loop, &self.wgpu, self.icon.clone(), window),
         );
     }
 }
@@ -210,11 +205,11 @@ impl ApplicationHandler<UserEvent> for Application {
                 self.open(event_loop, Box::new(about));
             }
             UserEvent::OpenCharacterData(sim_id) => {
-                let vram = CharacterDataWindow::new(sim_id);
+                let vram = CharacterDataWindow::new(sim_id, &mut self.memory);
                 self.open(event_loop, Box::new(vram));
             }
             UserEvent::OpenBgMap(sim_id) => {
-                let bgmap = BgMapWindow::new(sim_id);
+                let bgmap = BgMapWindow::new(sim_id, &mut self.memory);
                 self.open(event_loop, Box::new(bgmap));
             }
             UserEvent::OpenDebugger(sim_id) => {
@@ -328,7 +323,6 @@ impl Viewport {
         event_loop: &ActiveEventLoop,
         wgpu: &WgpuState,
         icon: Option<Arc<IconData>>,
-        vram: Arc<VramLoader>,
         mut app: Box<dyn AppWindow>,
     ) -> Self {
         let ctx = Context::default();
@@ -350,7 +344,6 @@ impl Viewport {
             s.visuals.menu_rounding = Default::default();
         });
         egui_extras::install_image_loaders(&ctx);
-        ctx.add_image_loader(vram);
 
         let wgpu_config = egui_wgpu::WgpuConfiguration {
             present_mode: wgpu::PresentMode::AutoNoVsync,
@@ -374,7 +367,7 @@ impl 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());
+        app.on_init(&ctx, painter.render_state().as_ref().unwrap());
         Self {
             painter,
             ctx,

src/main.rs

@@ -19,6 +19,7 @@ mod emulator;
 mod gdbserver;
 mod graphics;
 mod input;
+mod memory;
 mod persistence;
 mod vram;
 mod window;

src/memory.rs

@@ -0,0 +1,88 @@
+use std::{
+    collections::HashMap,
+    sync::{Arc, Mutex, MutexGuard},
+};
+
+use bytemuck::BoxBytes;
+
+use crate::emulator::{EmulatorClient, EmulatorCommand, SimId};
+
+pub struct MemoryMonitor {
+    client: EmulatorClient,
+    regions: HashMap<MemoryRegion, Arc<Mutex<BoxBytes>>>,
+}
+
+impl MemoryMonitor {
+    pub fn new(client: EmulatorClient) -> Self {
+        Self {
+            client,
+            regions: HashMap::new(),
+        }
+    }
+
+    pub fn view(&mut self, sim: SimId, start: u32, length: usize) -> MemoryView {
+        let region = MemoryRegion { sim, start, length };
+        let memory = self.regions.entry(region).or_insert_with(|| {
+            let mut buf = aligned_memory(start, length);
+            let (tx, rx) = oneshot::channel();
+            self.client
+                .send_command(EmulatorCommand::ReadMemory(sim, start, length, vec![], tx));
+            let bytes = pollster::block_on(rx).unwrap();
+            buf.copy_from_slice(&bytes);
+            #[expect(clippy::arc_with_non_send_sync)] // TODO: remove after bytemuck upgrade
+            Arc::new(Mutex::new(buf))
+        });
+        MemoryView {
+            memory: memory.clone(),
+        }
+    }
+}
+
+fn aligned_memory(start: u32, length: usize) -> BoxBytes {
+    if start % 4 == 0 && length % 4 == 0 {
+        let memory = vec![0u32; length / 4].into_boxed_slice();
+        return bytemuck::box_bytes_of(memory);
+    }
+    if start % 2 == 0 && length % 2 == 0 {
+        let memory = vec![0u16; length / 2].into_boxed_slice();
+        return bytemuck::box_bytes_of(memory);
+    }
+    let memory = vec![0u8; length].into_boxed_slice();
+    bytemuck::box_bytes_of(memory)
+}
+
+pub struct MemoryView {
+    memory: Arc<Mutex<BoxBytes>>,
+}
+// SAFETY: BoxBytes is supposed to be Send+Sync, will be in a new version
+unsafe impl Send for MemoryView {}
+
+impl MemoryView {
+    pub fn borrow(&self) -> MemoryRef<'_> {
+        MemoryRef {
+            inner: self.memory.lock().unwrap(),
+        }
+    }
+}
+
+pub struct MemoryRef<'a> {
+    inner: MutexGuard<'a, BoxBytes>,
+}
+
+impl MemoryRef<'_> {
+    pub fn read(&self, index: usize) -> u8 {
+        self.inner[index]
+    }
+    pub fn range<T: bytemuck::AnyBitPattern>(&self, start: usize, count: usize) -> &[T] {
+        let from = start * size_of::<T>();
+        let to = from + (count * size_of::<T>());
+        bytemuck::cast_slice(&self.inner[from..to])
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+struct MemoryRegion {
+    sim: SimId,
+    start: u32,
+    length: usize,
+}

src/vram.rs

@@ -1,208 +1,109 @@
-use serde::{Deserialize, Serialize};
 use std::{
     collections::{hash_map::Entry, HashMap},
-    fmt::Display,
-    sync::{Arc, Mutex},
+    hash::Hash,
+    sync::Mutex,
 };
-use tokio::sync::mpsc;
 
 use egui::{
-    load::{ImageLoader, ImagePoll, LoadError},
-    ColorImage, Context, Vec2,
+    epaint::ImageDelta,
+    load::{LoadError, SizedTexture, TextureLoader, TexturePoll},
+    ColorImage, Context, TextureHandle, TextureOptions,
 };
+use serde::{Deserialize, Serialize};
 
-use crate::emulator::{EmulatorClient, EmulatorCommand, SimId};
-
-enum VramRequest {
-    Load(String, VramResource),
+pub trait VramResource: Sized + PartialEq + Eq + Hash {
+    fn to_uri(&self) -> String;
+    fn from_uri(uri: &str) -> Option<Self>;
 }
 
-enum VramResponse {
-    Loaded(String, ColorImage),
+impl<T: Serialize + for<'a> Deserialize<'a> + PartialEq + Eq + Hash> VramResource for T {
+    fn to_uri(&self) -> String {
+        format!("vram://{}", serde_json::to_string(self).unwrap())
     }
 
-pub struct VramResource {
-    sim: SimId,
-    kind: VramResourceKind,
+    fn from_uri(uri: &str) -> Option<Self> {
+        let content = uri.strip_prefix("vram://")?;
+        serde_json::from_str(content).ok()
+    }
 }
 
-impl VramResource {
-    pub fn character_data(sim: SimId, palette: VramPalette) -> Self {
-        Self {
-            sim,
-            kind: VramResourceKind::CharacterData { palette },
-        }
-    }
-
-    pub fn character(sim: SimId, palette: VramPalette, index: usize) -> Self {
-        Self {
-            sim,
-            kind: VramResourceKind::Character { palette, index },
-        }
-    }
-
-    pub fn palette_color(sim: SimId, palette: VramPalette, index: usize) -> Self {
-        Self {
-            sim,
-            kind: VramResourceKind::PaletteColor { palette, index },
-        }
-    }
-
-    pub fn to_uri(&self) -> String {
-        format!(
-            "vram://{}:{}",
-            self.sim.to_index(),
-            serde_json::to_string(&self.kind).unwrap(),
-        )
-    }
-
-    fn from_uri(uri: &str) -> Option<VramResource> {
-        let uri = uri.strip_prefix("vram://")?;
-        let (sim, uri) = match uri.split_at_checked(2)? {
-            ("0:", rest) => (SimId::Player1, rest),
-            ("1:", rest) => (SimId::Player2, rest),
-            _ => return None,
-        };
-        let kind = serde_json::from_str(uri).ok()?;
-        Some(Self { sim, kind })
-    }
-}
-
-#[derive(Serialize, Deserialize)]
-enum VramResourceKind {
-    Character { palette: VramPalette, index: usize },
-    CharacterData { palette: VramPalette },
-    PaletteColor { palette: VramPalette, index: usize },
-}
-
-impl VramResourceKind {
-    fn size(&self) -> Option<Vec2> {
-        match self {
-            Self::Character { .. } => Some((8.0, 8.0).into()),
-            Self::CharacterData { .. } => Some((8.0 * 16.0, 8.0 * 128.0).into()),
-            Self::PaletteColor { .. } => Some((1.0, 1.0).into()),
-        }
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
-pub enum VramPalette {
-    Generic,
-    Bg0,
-    Bg1,
-    Bg2,
-    Bg3,
-    Obj0,
-    Obj1,
-    Obj2,
-    Obj3,
-}
-
-impl VramPalette {
-    pub const fn values() -> [VramPalette; 9] {
-        [
-            Self::Generic,
-            Self::Bg0,
-            Self::Bg1,
-            Self::Bg2,
-            Self::Bg3,
-            Self::Obj0,
-            Self::Obj1,
-            Self::Obj2,
-            Self::Obj3,
-        ]
-    }
-}
-
-impl Display for VramPalette {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Self::Generic => f.write_str("Generic"),
-            Self::Bg0 => f.write_str("BG 0"),
-            Self::Bg1 => f.write_str("BG 1"),
-            Self::Bg2 => f.write_str("BG 2"),
-            Self::Bg3 => f.write_str("BG 3"),
-            Self::Obj0 => f.write_str("OBJ 0"),
-            Self::Obj1 => f.write_str("OBJ 1"),
-            Self::Obj2 => f.write_str("OBJ 2"),
-            Self::Obj3 => f.write_str("OBJ 3"),
-        }
-    }
-}
-
-pub struct VramLoader {
-    cache: Mutex<HashMap<String, ImagePoll>>,
-    source: Mutex<mpsc::UnboundedReceiver<VramResponse>>,
-    sink: mpsc::UnboundedSender<VramRequest>,
-}
-
-impl VramLoader {
-    pub fn new(client: EmulatorClient) -> Self {
-        let (tx1, rx1) = mpsc::unbounded_channel();
-        let (tx2, rx2) = mpsc::unbounded_channel();
-        std::thread::spawn(move || {
-            tokio::runtime::Builder::new_current_thread()
-                .enable_all()
-                .build()
-                .unwrap()
-                .block_on(async move {
-                    let worker = VramLoadingWorker::new(rx2, tx1, client);
-                    worker.run().await;
-                })
-        });
+pub trait VramImageLoader {
+    type Resource: VramResource;
+
+    fn id(&self) -> &str;
+    fn add(&self, resource: &Self::Resource) -> Option<ColorImage>;
+    fn update<'a>(
+        &'a self,
+        resources: impl Iterator<Item = &'a Self::Resource>,
+    ) -> Vec<(&'a Self::Resource, ColorImage)>;
+}
+
+pub struct VramTextureLoader<T: VramImageLoader> {
+    id: String,
+    loader: Mutex<T>,
+    cache: Mutex<HashMap<T::Resource, TextureHandle>>,
+}
+
+impl<T: VramImageLoader> VramTextureLoader<T> {
+    pub fn new(loader: T) -> Self {
         Self {
+            id: loader.id().to_string(),
+            loader: Mutex::new(loader),
             cache: Mutex::new(HashMap::new()),
-            source: Mutex::new(rx1),
-            sink: tx2,
         }
     }
 }
 
-impl ImageLoader for VramLoader {
+impl<T: VramImageLoader> TextureLoader for VramTextureLoader<T> {
     fn id(&self) -> &str {
-        concat!(module_path!(), "::VramLoader")
+        &self.id
     }
 
     fn load(
         &self,
-        _ctx: &Context,
+        ctx: &Context,
         uri: &str,
+        texture_options: TextureOptions,
         _size_hint: egui::SizeHint,
-    ) -> Result<ImagePoll, LoadError> {
-        let Some(resource) = VramResource::from_uri(uri) else {
+    ) -> Result<TexturePoll, LoadError> {
+        let Some(resource) = T::Resource::from_uri(uri) else {
             return Err(LoadError::NotSupported);
         };
+        if texture_options != TextureOptions::NEAREST {
+            return Err(LoadError::Loading(
+                "Only TextureOptions::NEAREST are supported".into(),
+            ));
+        }
+        let loader = self.loader.lock().unwrap();
         let mut cache = self.cache.lock().unwrap();
-        {
-            let mut source = self.source.lock().unwrap();
-            while let Ok(response) = source.try_recv() {
-                match response {
-                    VramResponse::Loaded(uri, image) => {
-                        cache.insert(
-                            uri,
-                            ImagePoll::Ready {
-                                image: Arc::new(image),
-                            },
-                        );
+        for (resource, updated_image) in loader.update(cache.keys()) {
+            if let Some(handle) = cache.get(resource) {
+                let delta = ImageDelta::full(updated_image, TextureOptions::NEAREST);
+                ctx.tex_manager().write().set(handle.id(), delta);
             }
         }
+        match cache.entry(resource) {
+            Entry::Occupied(entry) => {
+                let texture = SizedTexture::from_handle(entry.get());
+                Ok(TexturePoll::Ready { texture })
             }
-        }
-        let poll = match cache.entry(uri.to_string()) {
-            Entry::Occupied(entry) => entry.into_mut(),
             Entry::Vacant(entry) => {
-                let pending = ImagePoll::Pending {
-                    size: resource.kind.size(),
-                };
-                let _ = self.sink.send(VramRequest::Load(uri.to_string(), resource));
-                entry.insert(pending)
+                if let Some(image) = loader.add(entry.key()) {
+                    let handle =
+                        entry.insert(ctx.load_texture(uri, image, TextureOptions::NEAREST));
+                    let texture = SizedTexture::from_handle(handle);
+                    Ok(TexturePoll::Ready { texture })
+                } else {
+                    Err(LoadError::Loading("could not load texture".into()))
+                }
+            }
         }
-        };
-        Ok(poll.clone())
     }
 
     fn forget(&self, uri: &str) {
-        self.cache.lock().unwrap().remove(uri);
+        if let Some(resource) = T::Resource::from_uri(uri) {
+            self.cache.lock().unwrap().remove(&resource);
+        }
     }
 
     fn forget_all(&self) {
@@ -214,159 +115,7 @@ impl ImageLoader for VramLoader {
             .lock()
             .unwrap()
             .values()
-            .map(|c| match c {
-                ImagePoll::Pending { .. } => 0,
-                ImagePoll::Ready { image } => image.pixels.len() * size_of::<ColorImage>(),
-            })
+            .map(|h| h.byte_size())
             .sum()
     }
 }
-
-struct VramLoadingWorker {
-    source: mpsc::UnboundedReceiver<VramRequest>,
-    sink: mpsc::UnboundedSender<VramResponse>,
-    client: EmulatorClient,
-}
-
-impl VramLoadingWorker {
-    fn new(
-        source: mpsc::UnboundedReceiver<VramRequest>,
-        sink: mpsc::UnboundedSender<VramResponse>,
-        client: EmulatorClient,
-    ) -> Self {
-        Self {
-            source,
-            sink,
-            client,
-        }
-    }
-    async fn run(mut self) {
-        while let Some(request) = self.source.recv().await {
-            #[allow(irrefutable_let_patterns)]
-            if let VramRequest::Load(uri, resource) = request {
-                let Some(image) = self.load(resource).await else {
-                    continue;
-                };
-                if self.sink.send(VramResponse::Loaded(uri, image)).is_err() {
-                    return;
-                }
-            }
-        }
-    }
-
-    async fn load(&self, resource: VramResource) -> Option<ColorImage> {
-        let sim = resource.sim;
-        match resource.kind {
-            VramResourceKind::Character { palette, index } => {
-                self.load_character(sim, palette, index).await
-            }
-            VramResourceKind::CharacterData { palette } => {
-                self.load_character_data(sim, palette).await
-            }
-            VramResourceKind::PaletteColor { palette, index } => {
-                self.load_palette_color(sim, palette, index).await
-            }
-        }
-    }
-
-    async fn load_character(
-        &self,
-        sim: SimId,
-        palette: VramPalette,
-        index: usize,
-    ) -> Option<ColorImage> {
-        if index >= 2048 {
-            return None;
-        }
-        let address = 0x00078000 + (index as u32 * 16);
-        let (memory, palette) = tokio::join!(
-            self.read_memory(sim, address, 16),
-            self.load_palette_colors(sim, palette),
-        );
-        let palette = palette?;
-        let mut buffer = vec![];
-        for byte in memory? {
-            for offset in (0..8).step_by(2) {
-                let char = (byte >> offset) & 0x3;
-                buffer.push(palette[char as usize]);
-            }
-        }
-        Some(ColorImage::from_gray([8, 8], &buffer))
-    }
-
-    async fn load_character_data(&self, sim: SimId, palette: VramPalette) -> Option<ColorImage> {
-        let (memory, palette) = tokio::join!(
-            self.read_memory(sim, 0x00078000, 16 * 2048),
-            self.load_palette_colors(sim, palette),
-        );
-        let palette = palette?;
-        let mut buffer = vec![0; 8 * 8 * 2048];
-        for (i, byte) in memory?.into_iter().enumerate() {
-            let bytes = [0, 2, 4, 6].map(|off| palette[(byte as usize >> off) & 0x3]);
-            let char_index = i / 16;
-            let in_char_pos = i % 16;
-            let x = ((char_index % 16) * 8) + ((in_char_pos % 2) * 4);
-            let y = ((char_index / 16) * 8) + (in_char_pos / 2);
-            let write_index = (y * 16 * 8) + x;
-            buffer[write_index..(write_index + 4)].copy_from_slice(&bytes);
-        }
-        Some(ColorImage::from_gray([8 * 16, 8 * 128], &buffer))
-    }
-
-    async fn load_palette_color(
-        &self,
-        sim: SimId,
-        palette: VramPalette,
-        index: usize,
-    ) -> Option<ColorImage> {
-        if index == 0 {
-            return Some(ColorImage::from_gray([1, 1], &[0]));
-        }
-        if index > 3 {
-            return None;
-        }
-        let shade = *self.load_palette_colors(sim, palette).await?.get(index)?;
-        Some(ColorImage::from_gray([1, 1], &[shade]))
-    }
-
-    async fn load_palette_colors(&self, sim: SimId, palette: VramPalette) -> Option<[u8; 4]> {
-        let offset = match palette {
-            VramPalette::Generic => {
-                return Some([0, 64, 128, 255]);
-            }
-            VramPalette::Bg0 => 0,
-            VramPalette::Bg1 => 2,
-            VramPalette::Bg2 => 4,
-            VramPalette::Bg3 => 6,
-            VramPalette::Obj0 => 8,
-            VramPalette::Obj1 => 10,
-            VramPalette::Obj2 => 12,
-            VramPalette::Obj3 => 14,
-        };
-        let (palettes, brightnesses) = tokio::join!(
-            self.read_memory(sim, 0x0005f860, 16),
-            self.read_memory(sim, 0x0005f824, 6),
-        );
-        let palette = *palettes?.get(offset)?;
-        let brts = brightnesses?;
-        let shades = [
-            0,
-            brts[0],
-            brts[2],
-            brts[0].saturating_add(brts[2]).saturating_add(brts[4]),
-        ];
-        Some([
-            0,
-            shades[(palette >> 2) as usize & 0x03],
-            shades[(palette >> 4) as usize & 0x03],
-            shades[(palette >> 6) as usize & 0x03],
-        ])
-    }
-
-    async fn read_memory(&self, sim: SimId, address: u32, size: usize) -> Option<Vec<u8>> {
-        let (tx, rx) = oneshot::channel();
-        self.client
-            .send_command(EmulatorCommand::ReadMemory(sim, address, size, vec![], tx));
-        rx.await.ok()
-    }
-}

src/window.rs

@@ -22,7 +22,8 @@ pub trait AppWindow {
     }
     fn initial_viewport(&self) -> ViewportBuilder;
     fn show(&mut self, ctx: &Context);
-    fn on_init(&mut self, render_state: &egui_wgpu::RenderState) {
+    fn on_init(&mut self, ctx: &Context, render_state: &egui_wgpu::RenderState) {
+        let _ = ctx;
         let _ = render_state;
     }
     fn on_destroy(&mut self) {}

src/window/game.rs

@@ -377,7 +377,7 @@ impl AppWindow for GameWindow {
         toasts.show(ctx);
     }
 
-    fn on_init(&mut self, render_state: &egui_wgpu::RenderState) {
+    fn on_init(&mut self, _ctx: &Context, render_state: &egui_wgpu::RenderState) {
         let (screen, sink) = GameScreen::init(render_state);
         let (message_sink, message_source) = mpsc::channel();
         self.client.send_command(EmulatorCommand::ConnectToSim(

src/window/vram.rs

@@ -1,5 +1,6 @@
 mod bgmap;
 mod chardata;
+mod utils;
 
 pub use bgmap::*;
 pub use chardata::*;

src/window/vram/bgmap.rs

@@ -1,14 +1,28 @@
-use egui::{CentralPanel, Context, ViewportBuilder, ViewportId};
+use std::sync::Arc;
 
-use crate::{emulator::SimId, window::AppWindow};
+use egui::{CentralPanel, ColorImage, Context, Image, TextureOptions, ViewportBuilder, ViewportId};
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    emulator::SimId,
+    memory::{MemoryMonitor, MemoryView},
+    vram::{VramImageLoader, VramResource as _, VramTextureLoader},
+    window::AppWindow,
+};
+
+use super::utils::parse_palette;
 
 pub struct BgMapWindow {
     sim_id: SimId,
+    loader: Option<BgMapLoader>,
 }
 
 impl BgMapWindow {
-    pub fn new(sim_id: SimId) -> Self {
-        Self { sim_id }
+    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
+        Self {
+            sim_id,
+            loader: Some(BgMapLoader::new(sim_id, memory)),
+        }
     }
 }
 
@@ -17,13 +31,121 @@ impl AppWindow for BgMapWindow {
         ViewportId::from_hash_of(format!("bgmap-{}", self.sim_id))
     }
 
+    fn sim_id(&self) -> SimId {
+        self.sim_id
+    }
+
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
             .with_title(format!("BG Map Data ({})", self.sim_id))
             .with_inner_size((640.0, 480.0))
     }
 
+    fn on_init(&mut self, ctx: &Context, _render_state: &egui_wgpu::RenderState) {
+        let loader = self.loader.take().unwrap();
+        ctx.add_texture_loader(Arc::new(VramTextureLoader::new(loader)));
+    }
+
     fn show(&mut self, ctx: &Context) {
-        CentralPanel::default().show(ctx, |ui| ui.label("TODO"));
+        CentralPanel::default().show(ctx, |ui| {
+            let resource = BgMapResource { index: 0 };
+            let image = Image::new(resource.to_uri()).texture_options(TextureOptions::NEAREST);
+            ui.add(image);
+        });
+    }
+}
+
+#[derive(Serialize, Deserialize, PartialEq, Eq, Hash)]
+struct BgMapResource {
+    index: usize,
+}
+
+struct BgMapLoader {
+    chardata: MemoryView,
+    bgmaps: MemoryView,
+    brightness: MemoryView,
+    palettes: MemoryView,
+}
+
+impl BgMapLoader {
+    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
+        Self {
+            chardata: memory.view(sim_id, 0x00078000, 0x8000),
+            bgmaps: memory.view(sim_id, 0x00020000, 0x1d800),
+            brightness: memory.view(sim_id, 0x0005f824, 8),
+            palettes: memory.view(sim_id, 0x0005f860, 16),
+        }
+    }
+
+    fn load_bgmap(&self, index: usize) -> Option<ColorImage> {
+        let chardata = self.chardata.borrow();
+        let bgmaps = self.bgmaps.borrow();
+        let brightness = self.brightness.borrow();
+        let palettes = self.palettes.borrow();
+
+        let brts = brightness.range::<u8>(0, 8);
+        let colors = [
+            parse_palette(palettes.read(0), brts),
+            parse_palette(palettes.read(2), brts),
+            parse_palette(palettes.read(4), brts),
+            parse_palette(palettes.read(6), brts),
+        ];
+
+        let mut data = vec![0u8; 512 * 512];
+        for (i, cell) in bgmaps.range::<u16>(index * 4096, 4096).iter().enumerate() {
+            let char_index = (cell & 0x7ff) as usize;
+            let char = chardata.range::<u16>(char_index * 8, 8);
+            let vflip = cell & 0x1000 != 0;
+            let hflip = cell & 0x2000 != 0;
+            let palette_index = (cell >> 14) as usize;
+            let palette = &colors[palette_index];
+
+            let mut target_idx = (i % 64) * 8 + (i / 64) * 8 * 512;
+            for row in 0..8 {
+                let dests = &mut data[target_idx..target_idx + 8];
+                let pixels = self.read_char_row(char, hflip, vflip, row);
+                for (dest, pixel) in dests.iter_mut().zip(pixels) {
+                    *dest = palette[pixel as usize];
+                }
+                target_idx += 512;
+            }
+        }
+
+        Some(ColorImage::from_gray([512, 512], &data))
+    }
+
+    fn read_char_row(
+        &self,
+        char: &[u16],
+        hflip: bool,
+        vflip: bool,
+        row: usize,
+    ) -> impl Iterator<Item = u8> {
+        let pixels = if vflip { char[7 - row] } else { char[row] };
+        (0..16).step_by(2).map(move |i| {
+            let pixel = if hflip { 14 - i } else { i };
+            ((pixels >> pixel) & 0x3) as u8
+        })
+    }
+}
+
+impl VramImageLoader for BgMapLoader {
+    type Resource = BgMapResource;
+
+    fn id(&self) -> &str {
+        concat!(module_path!(), "::BgMapLoader")
+    }
+
+    fn add(&self, resource: &Self::Resource) -> Option<ColorImage> {
+        let BgMapResource { index } = resource;
+        self.load_bgmap(*index)
+    }
+
+    fn update<'a>(
+        &'a self,
+        resources: impl Iterator<Item = &'a Self::Resource>,
+    ) -> Vec<(&'a Self::Resource, ColorImage)> {
+        let _ = resources;
+        vec![]
     }
 }

src/window/vram/chardata.rs

@@ -1,17 +1,86 @@
+use std::{fmt::Display, sync::Arc};
+
 use egui::{
-    Align, CentralPanel, Color32, ComboBox, Context, Frame, Image, RichText, ScrollArea, Sense,
-    Slider, TextEdit, TextureOptions, Ui, UiBuilder, Vec2, ViewportBuilder, ViewportId,
+    Align, CentralPanel, Color32, ColorImage, ComboBox, Context, Frame, Image, RichText,
+    ScrollArea, Sense, Slider, TextEdit, TextureOptions, Ui, UiBuilder, Vec2, ViewportBuilder,
+    ViewportId,
 };
 use egui_extras::{Column, Size, StripBuilder, TableBuilder};
+use serde::{Deserialize, Serialize};
 
 use crate::{
     emulator::SimId,
-    vram::{VramPalette, VramResource},
+    memory::{MemoryMonitor, MemoryView},
+    vram::{VramImageLoader, VramResource as _, VramTextureLoader},
     window::AppWindow,
 };
 
+use super::utils;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+pub enum VramPalette {
+    Generic,
+    Bg0,
+    Bg1,
+    Bg2,
+    Bg3,
+    Obj0,
+    Obj1,
+    Obj2,
+    Obj3,
+}
+
+impl VramPalette {
+    pub const fn values() -> [VramPalette; 9] {
+        [
+            Self::Generic,
+            Self::Bg0,
+            Self::Bg1,
+            Self::Bg2,
+            Self::Bg3,
+            Self::Obj0,
+            Self::Obj1,
+            Self::Obj2,
+            Self::Obj3,
+        ]
+    }
+
+    pub const fn offset(self) -> Option<usize> {
+        match self {
+            Self::Generic => None,
+            Self::Bg0 => Some(0),
+            Self::Bg1 => Some(2),
+            Self::Bg2 => Some(4),
+            Self::Bg3 => Some(6),
+            Self::Obj0 => Some(8),
+            Self::Obj1 => Some(10),
+            Self::Obj2 => Some(12),
+            Self::Obj3 => Some(14),
+        }
+    }
+}
+
+impl Display for VramPalette {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Generic => f.write_str("Generic"),
+            Self::Bg0 => f.write_str("BG 0"),
+            Self::Bg1 => f.write_str("BG 1"),
+            Self::Bg2 => f.write_str("BG 2"),
+            Self::Bg3 => f.write_str("BG 3"),
+            Self::Obj0 => f.write_str("OBJ 0"),
+            Self::Obj1 => f.write_str("OBJ 1"),
+            Self::Obj2 => f.write_str("OBJ 2"),
+            Self::Obj3 => f.write_str("OBJ 3"),
+        }
+    }
+}
+
 pub struct CharacterDataWindow {
     sim_id: SimId,
+    loader: Option<CharDataLoader>,
+    brightness: MemoryView,
+    palettes: MemoryView,
     palette: VramPalette,
     index: usize,
     index_str: String,
@@ -20,9 +89,12 @@ pub struct CharacterDataWindow {
 }
 
 impl CharacterDataWindow {
-    pub fn new(sim_id: SimId) -> Self {
+    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
         Self {
             sim_id,
+            loader: Some(CharDataLoader::new(sim_id, memory)),
+            brightness: memory.view(sim_id, 0x0005f824, 8),
+            palettes: memory.view(sim_id, 0x0005f860, 16),
             palette: VramPalette::Generic,
             index: 0,
             index_str: "0".into(),
@@ -89,7 +161,10 @@ impl CharacterDataWindow {
                         });
                     });
                 });
-            let resource = VramResource::character(self.sim_id, self.palette, self.index);
+            let resource = CharDataResource::Character {
+                palette: self.palette,
+                index: self.index,
+            };
             let image = Image::new(resource.to_uri())
                 .maintain_aspect_ratio(true)
                 .tint(Color32::RED)
@@ -114,18 +189,18 @@ impl CharacterDataWindow {
                 TableBuilder::new(ui)
                     .columns(Column::remainder(), 4)
                     .body(|mut body| {
+                        let palette = self.load_palette_colors();
                         body.row(30.0, |mut row| {
-                            for index in 0..4 {
-                                let resource =
-                                    VramResource::palette_color(self.sim_id, self.palette, index);
+                            for color in palette {
                                 row.col(|ui| {
                                     let rect = ui.available_rect_before_wrap();
                                     let scale = rect.height() / rect.width();
                                     let rect = rect.scale_from_center2(Vec2::new(scale, 1.0));
-                                    let image = Image::new(resource.to_uri())
-                                        .tint(Color32::RED)
-                                        .fit_to_exact_size(rect.max - rect.min);
-                                    ui.put(rect, image);
+                                    ui.painter().rect_filled(
+                                        rect,
+                                        0.0,
+                                        Color32::RED * Color32::from_gray(color),
+                                    );
                                 });
                             }
                         });
@@ -145,9 +220,21 @@ impl CharacterDataWindow {
         });
     }
 
+    fn load_palette_colors(&self) -> [u8; 4] {
+        let Some(offset) = self.palette.offset() else {
+            return utils::GENERIC_PALETTE;
+        };
+        let palette = self.palettes.borrow().read(offset);
+        let brightnesses = self.brightness.borrow();
+        let brts = brightnesses.range(0, 8);
+        utils::parse_palette(palette, brts)
+    }
+
     fn show_chardata(&mut self, ui: &mut Ui) {
         let start_pos = ui.cursor().min;
-        let resource = VramResource::character_data(self.sim_id, self.palette);
+        let resource = CharDataResource::CharacterData {
+            palette: self.palette,
+        };
         let image = Image::new(resource.to_uri())
             .fit_to_original_size(self.scale)
             .tint(Color32::RED)
@@ -210,6 +297,11 @@ impl AppWindow for CharacterDataWindow {
             .with_inner_size((640.0, 480.0))
     }
 
+    fn on_init(&mut self, ctx: &Context, _render_state: &egui_wgpu::RenderState) {
+        let loader = self.loader.take().unwrap();
+        ctx.add_texture_loader(Arc::new(VramTextureLoader::new(loader)));
+    }
+
     fn show(&mut self, ctx: &Context) {
         CentralPanel::default().show(ctx, |ui| {
             ui.horizontal_top(|ui| {
@@ -229,6 +321,95 @@ impl AppWindow for CharacterDataWindow {
     }
 }
 
+#[derive(Serialize, Deserialize, PartialEq, Eq, Hash)]
+enum CharDataResource {
+    Character { palette: VramPalette, index: usize },
+    CharacterData { palette: VramPalette },
+}
+
+struct CharDataLoader {
+    chardata: MemoryView,
+    brightness: MemoryView,
+    palettes: MemoryView,
+}
+
+impl CharDataLoader {
+    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
+        Self {
+            chardata: memory.view(sim_id, 0x00078000, 0x8000),
+            brightness: memory.view(sim_id, 0x0005f824, 8),
+            palettes: memory.view(sim_id, 0x0005f860, 16),
+        }
+    }
+
+    fn load_character(&self, palette: VramPalette, index: usize) -> Option<ColorImage> {
+        if index >= 2048 {
+            return None;
+        }
+        let palette = self.load_palette(palette);
+        let chardata = self.chardata.borrow();
+        let character = chardata.range::<u16>(index * 8, 8);
+        let mut buffer = Vec::with_capacity(8 * 8);
+        for row in character {
+            for offset in (0..16).step_by(2) {
+                let char = (row >> offset) & 0x3;
+                buffer.push(palette[char as usize]);
+            }
+        }
+        Some(ColorImage::from_gray([8, 8], &buffer))
+    }
+
+    fn load_character_data(&self, palette: VramPalette) -> Option<ColorImage> {
+        let palette = self.load_palette(palette);
+        let chardata = self.chardata.borrow();
+        let mut buffer = vec![0; 8 * 8 * 2048];
+        for (i, row) in chardata.range::<u16>(0, 2048).iter().enumerate() {
+            let bytes =
+                [0, 2, 4, 6, 8, 10, 12, 14].map(|off| palette[(*row as usize >> off) & 0x3]);
+            let char_index = i / 8;
+            let row_index = i % 8;
+            let x = (char_index % 16) * 8;
+            let y = (char_index / 16) * 8 + row_index;
+            let write_index = (y * 16 * 8) + x;
+            buffer[write_index..write_index + 8].copy_from_slice(&bytes);
+        }
+        Some(ColorImage::from_gray([8 * 16, 8 * 128], &buffer))
+    }
+
+    fn load_palette(&self, palette: VramPalette) -> [u8; 4] {
+        let Some(offset) = palette.offset() else {
+            return utils::GENERIC_PALETTE;
+        };
+        let palette = self.palettes.borrow().read(offset);
+        let brightnesses = self.brightness.borrow();
+        let brts = brightnesses.range(0, 8);
+        utils::parse_palette(palette, brts)
+    }
+}
+
+impl VramImageLoader for CharDataLoader {
+    type Resource = CharDataResource;
+
+    fn id(&self) -> &str {
+        concat!(module_path!(), "::CharDataLoader")
+    }
+
+    fn add(&self, resource: &Self::Resource) -> Option<ColorImage> {
+        match resource {
+            CharDataResource::Character { palette, index } => self.load_character(*palette, *index),
+            CharDataResource::CharacterData { palette } => self.load_character_data(*palette),
+        }
+    }
+
+    fn update<'a>(
+        &'a self,
+        resources: impl Iterator<Item = &'a Self::Resource>,
+    ) -> Vec<(&'a Self::Resource, ColorImage)> {
+        let _ = resources;
+        vec![]
+    }
+}
+
 trait UiExt {
     fn section(&mut self, title: impl Into<String>, add_contents: impl FnOnce(&mut Ui));
 }

src/window/vram/utils.rs

@@ -0,0 +1,16 @@
+pub const GENERIC_PALETTE: [u8; 4] = [0, 64, 128, 255];
+
+pub fn parse_palette(palette: u8, brts: &[u8]) -> [u8; 4] {
+    let shades = [
+        0,
+        brts[0],
+        brts[2],
+        brts[0].saturating_add(brts[2]).saturating_add(brts[4]),
+    ];
+    [
+        0,
+        shades[(palette >> 2) as usize & 0x03],
+        shades[(palette >> 4) as usize & 0x03],
+        shades[(palette >> 6) as usize & 0x03],
+    ]
+}