a mad redo of how objects work

agb/Cargo.toml

@@ -30,6 +30,7 @@ agb_fixnum = { version = "0.13.0", path = "../agb-fixnum" }
 bare-metal = "1"
 modular-bitfield = "0.11"
 rustc-hash =  { version = "1", default-features = false }
+slotmap = { version = "1.0", default-features = false }
 
 [package.metadata.docs.rs]
 default-target = "thumbv6m-none-eabi"

agb/examples/chicken.rs

@@ -4,7 +4,7 @@
 use agb::{
     display::tiled::{TileFormat, TileSet, TileSetting, TiledMap},
     display::{
-        object::{Object, ObjectController, Size, Sprite},
+        object::{Object, Size, Sprite, StaticSpriteLoader},
         palette16::Palette16,
         tiled::RegularBackgroundSize,
         HEIGHT, WIDTH,
@@ -74,11 +74,11 @@ fn main(mut gba: agb::Gba) -> ! {
     background.show();
     background.commit(&mut vram);
 
-    let object = gba.display.object.get();
+    let (object, mut sprites) = gba.display.object.get_managed();
 
-    let sprite = object.sprite(&CHICKEN_SPRITES[0]);
+    let sprite = sprites.get_vram_sprite(&CHICKEN_SPRITES[0]);
     let mut chicken = Character {
-        object: object.object(sprite),
+        object: object.add_object(sprite),
         position: Vector2D {
             x: (6 * 8) << 8,
             y: ((7 * 8) - 4) << 8,
@@ -137,15 +137,15 @@ fn main(mut gba: agb::Gba) -> ! {
         }
 
         restrict_to_screen(&mut chicken);
-        update_chicken_object(&mut chicken, &object, state, frame_count);
+        update_chicken_object(&mut chicken, &mut sprites, state, frame_count);
 
         object.commit();
     }
 }
 
-fn update_chicken_object<'a>(
-    chicken: &'_ mut Character<'a>,
-    object: &'a ObjectController,
+fn update_chicken_object(
+    chicken: &'_ mut Character<'_>,
+    sprites: &mut StaticSpriteLoader,
     state: State,
     frame_count: u32,
 ) {
@@ -158,19 +158,19 @@ fn update_chicken_object<'a>(
         State::Ground => {
             if chicken.velocity.x.abs() > 1 << 4 {
                 chicken.object.set_sprite(
-                    object.sprite(&CHICKEN_SPRITES[frame_ranger(frame_count, 1, 3, 10)]),
+                    sprites.get_vram_sprite(&CHICKEN_SPRITES[frame_ranger(frame_count, 1, 3, 10)]),
                 );
             } else {
                 chicken
                     .object
-                    .set_sprite(object.sprite(&CHICKEN_SPRITES[0]));
+                    .set_sprite(sprites.get_vram_sprite(&CHICKEN_SPRITES[0]));
             }
         }
         State::Upwards => {}
         State::Flapping => {
-            chicken
-                .object
-                .set_sprite(object.sprite(&CHICKEN_SPRITES[frame_ranger(frame_count, 4, 5, 5)]));
+            chicken.object.set_sprite(
+                sprites.get_vram_sprite(&CHICKEN_SPRITES[frame_ranger(frame_count, 4, 5, 5)]),
+            );
         }
     }
 

agb/examples/sprites.rs

@@ -3,7 +3,7 @@
 
 extern crate alloc;
 
-use agb::display::object::{Graphics, ObjectController, Sprite, TagMap};
+use agb::display::object::{Graphics, OAMManager, Sprite, StaticSpriteLoader, TagMap};
 use alloc::vec::Vec;
 
 const GRAPHICS: &Graphics = agb::include_aseprite!(
@@ -15,13 +15,13 @@ const GRAPHICS: &Graphics = agb::include_aseprite!(
 const SPRITES: &[Sprite] = GRAPHICS.sprites();
 const TAG_MAP: &TagMap = GRAPHICS.tags();
 
-fn all_sprites(gfx: &ObjectController) {
+fn all_sprites(gfx: &OAMManager, sprites: &mut StaticSpriteLoader) {
     let mut input = agb::input::ButtonController::new();
     let mut objs = Vec::new();
 
     for y in 0..9 {
         for x in 0..14 {
-            let mut obj = gfx.object(gfx.sprite(&SPRITES[0]));
+            let mut obj = gfx.add_object(sprites.get_vram_sprite(&SPRITES[0]));
             obj.show();
             obj.set_position((x * 16 + 8, y * 16 + 8).into());
             objs.push(obj);
@@ -48,14 +48,14 @@ fn all_sprites(gfx: &ObjectController) {
             image %= SPRITES.len();
             for (i, obj) in objs.iter_mut().enumerate() {
                 let this_image = (image + i) % SPRITES.len();
-                obj.set_sprite(gfx.sprite(&SPRITES[this_image]));
+                obj.set_sprite(sprites.get_vram_sprite(&SPRITES[this_image]));
             }
             gfx.commit();
         }
     }
 }
 
-fn all_tags(gfx: &ObjectController) {
+fn all_tags(gfx: &OAMManager, sprites: &mut StaticSpriteLoader) {
     let mut input = agb::input::ButtonController::new();
     let mut objs = Vec::new();
 
@@ -65,7 +65,7 @@ fn all_tags(gfx: &ObjectController) {
         let sprite = v.sprite(0);
         let (size_x, size_y) = sprite.size().to_width_height();
         let (size_x, size_y) = (size_x as i32, size_y as i32);
-        let mut obj = gfx.object(gfx.sprite(sprite));
+        let mut obj = gfx.add_object(sprites.get_vram_sprite(sprite));
         obj.show();
         obj.set_position((x * 32 + 16 - size_x / 2, y * 32 + 16 - size_y / 2).into());
         objs.push((obj, v));
@@ -90,7 +90,7 @@ fn all_tags(gfx: &ObjectController) {
         if count % 5 == 0 {
             image += 1;
             for (obj, tag) in objs.iter_mut() {
-                obj.set_sprite(gfx.sprite(tag.animation_sprite(image)));
+                obj.set_sprite(sprites.get_vram_sprite(tag.animation_sprite(image)));
             }
             gfx.commit();
         }
@@ -99,12 +99,12 @@ fn all_tags(gfx: &ObjectController) {
 
 #[agb::entry]
 fn main(mut gba: agb::Gba) -> ! {
-    let gfx = gba.display.object.get();
+    let (gfx, mut ssl) = gba.display.object.get_managed();
 
     loop {
-        all_tags(&gfx);
+        all_tags(&gfx, &mut ssl);
         gfx.commit();
-        all_sprites(&gfx);
+        all_sprites(&gfx, &mut ssl);
         gfx.commit();
     }
 }

agb/src/display/mod.rs

@@ -4,7 +4,11 @@ use bitflags::bitflags;
 use modular_bitfield::BitfieldSpecifier;
 use video::Video;
 
-use self::{blend::Blend, object::ObjectController, window::Windows};
+use self::{
+    blend::Blend,
+    object::{initilise_oam, OAMManager, StaticSpriteLoader, UnmanagedOAM},
+    window::Windows,
+};
 
 /// Graphics mode 3. Bitmap mode that provides a 16-bit colour framebuffer.
 pub mod bitmap3;
@@ -80,8 +84,14 @@ pub struct Display {
 pub struct ObjectDistribution;
 
 impl ObjectDistribution {
-    pub fn get(&mut self) -> ObjectController<'_> {
-        ObjectController::new()
+    pub fn get_unmanaged(&mut self) -> (UnmanagedOAM<'_>, StaticSpriteLoader) {
+        unsafe { initilise_oam() };
+        (UnmanagedOAM::new(), StaticSpriteLoader::new())
+    }
+
+    pub fn get_managed(&mut self) -> (OAMManager<'_>, StaticSpriteLoader) {
+        unsafe { initilise_oam() };
+        (OAMManager::new(), StaticSpriteLoader::new())
     }
 }
 
@@ -143,7 +153,7 @@ pub fn busy_wait_for_vblank() {
     while VCOUNT.get() < 160 {}
 }
 
-#[derive(BitfieldSpecifier, Clone, Copy)]
+#[derive(BitfieldSpecifier, Clone, Copy, Debug)]
 pub enum Priority {
     P0 = 0,
     P1 = 1,

agb/src/display/object/managed.rs

@@ -0,0 +1,386 @@
+use core::{
+    cell::{Cell, UnsafeCell},
+    marker::PhantomData,
+};
+
+use agb_fixnum::Vector2D;
+use slotmap::{new_key_type, SlotMap};
+
+use crate::display::Priority;
+
+use super::{AffineMode, SpriteVram, UnmanagedOAM, UnmanagedObject};
+
+new_key_type! {struct ObjectKey; }
+
+#[derive(Clone, Copy)]
+struct Ordering {
+    next: Option<ObjectKey>,
+    previous: Option<ObjectKey>,
+}
+
+struct ObjectItem {
+    object: UnsafeCell<UnmanagedObject>,
+    z_order: Cell<Ordering>,
+    z_index: Cell<i32>,
+}
+
+struct Store {
+    store: UnsafeCell<slotmap::SlotMap<ObjectKey, ObjectItem>>,
+    first_z: Cell<Option<ObjectKey>>,
+}
+
+struct StoreIterator<'store> {
+    store: &'store slotmap::SlotMap<ObjectKey, ObjectItem>,
+    current: Option<ObjectKey>,
+}
+
+impl<'store> Iterator for StoreIterator<'store> {
+    type Item = &'store ObjectItem;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let to_output = &self.store[self.current?];
+        self.current = to_output.z_order.get().next;
+        Some(to_output)
+    }
+}
+
+impl Store {
+    /// SAFETY: while this exists, no other store related operations should be
+    /// performed. Notably this means you shouldn't drop the ObjectItem as this
+    /// implementation will touch this.
+    unsafe fn iter(&self) -> StoreIterator {
+        StoreIterator {
+            store: unsafe { &*self.store.get() },
+            current: self.first_z.get(),
+        }
+    }
+
+    fn is_all_ordered_right(&self) -> bool {
+        let mut previous_z = i32::MIN;
+        let mut current_index = self.first_z.get();
+
+        while let Some(ci) = current_index {
+            let obj = self.get_object(ci);
+            let this_z = obj.z_index.get();
+            if this_z < previous_z {
+                return false;
+            }
+            previous_z = this_z;
+            current_index = obj.z_order.get().next;
+        }
+
+        true
+    }
+
+    fn insert_object(&self, object: UnmanagedObject) -> Object {
+        let object_item = ObjectItem {
+            object: UnsafeCell::new(object),
+            z_order: Cell::new(Ordering {
+                next: None,
+                previous: None,
+            }),
+            z_index: Cell::new(0),
+        };
+        let idx = {
+            let data = unsafe { &mut *self.store.get() };
+            data.insert(object_item)
+        };
+
+        if let Some(first) = self.first_z.get() {
+            let mut this_index = first;
+            while self.get_object(this_index).z_index.get() < 0 {
+                if let Some(idx) = self.get_object(this_index).z_order.get().next {
+                    this_index = idx;
+                } else {
+                    break;
+                }
+            }
+            if self.get_object(this_index).z_index.get() < 0 {
+                add_after_element(self, idx, this_index);
+            } else {
+                add_before_element(self, idx, this_index);
+            }
+        } else {
+            self.first_z.set(Some(idx));
+        }
+
+        Object {
+            me: idx,
+            store: self,
+        }
+    }
+
+    fn remove_object(&self, object: ObjectKey) {
+        remove_from_linked_list(self, object);
+
+        let data = unsafe { &mut *self.store.get() };
+        data.remove(object);
+    }
+
+    fn get_object(&self, key: ObjectKey) -> &ObjectItem {
+        &(unsafe { &*self.store.get() }[key])
+    }
+}
+
+pub struct OAMManager<'gba> {
+    phantom: PhantomData<&'gba ()>,
+    object_store: Store,
+}
+
+impl OAMManager<'_> {
+    pub(crate) fn new() -> Self {
+        Self {
+            phantom: PhantomData,
+            object_store: Store {
+                store: UnsafeCell::new(SlotMap::with_key()),
+                first_z: Cell::new(None),
+            },
+        }
+    }
+
+    pub fn commit(&self) {
+        let mut count = 0;
+
+        let mut unmanaged = UnmanagedOAM::new();
+
+        for (object, mut slot) in unsafe { self.object_store.iter() }
+            .map(|item| unsafe { &*item.object.get() })
+            .filter(|object| object.is_visible())
+            .zip(unmanaged.iter())
+        {
+            slot.set(object);
+            count += 1;
+        }
+
+        crate::println!("{}", count);
+
+        unmanaged.clear_from(count);
+    }
+
+    pub fn add_object(&self, sprite: SpriteVram) -> Object<'_> {
+        self.object_store
+            .insert_object(UnmanagedObject::new(sprite))
+    }
+}
+
+pub struct Object<'controller> {
+    me: ObjectKey,
+    store: &'controller Store,
+}
+
+impl Drop for Object<'_> {
+    fn drop(&mut self) {
+        self.store.remove_object(self.me);
+    }
+}
+
+fn remove_from_linked_list(store: &Store, to_remove: ObjectKey) {
+    let my_current_neighbours = store.get_object(to_remove).z_order.get();
+
+    if let Some(previous) = my_current_neighbours.previous {
+        let stored_part = &store.get_object(previous).z_order;
+        let mut neighbour_left = stored_part.get();
+        neighbour_left.next = my_current_neighbours.next;
+        stored_part.set(neighbour_left);
+    } else {
+        store.first_z.set(my_current_neighbours.next);
+    }
+
+    if let Some(next) = my_current_neighbours.next {
+        let stored_part = &store.get_object(next).z_order;
+        let mut neighbour_right = stored_part.get();
+        neighbour_right.previous = my_current_neighbours.previous;
+        stored_part.set(neighbour_right);
+    }
+
+    store.get_object(to_remove).z_order.set(Ordering {
+        next: None,
+        previous: None,
+    });
+}
+
+fn add_before_element(store: &Store, elem: ObjectKey, before_this: ObjectKey) {
+    assert_ne!(elem, before_this);
+
+    let this_element_store = &store.get_object(elem).z_order;
+    let mut this_element = this_element_store.get();
+
+    let before_store = &store.get_object(before_this).z_order;
+    let mut before = before_store.get();
+
+    if let Some(previous) = before.previous {
+        let neighbour_left_store = &store.get_object(previous).z_order;
+        let mut neighbour_left = neighbour_left_store.get();
+        neighbour_left.next = Some(elem);
+        neighbour_left_store.set(neighbour_left);
+    } else {
+        store.first_z.set(Some(elem));
+    }
+    this_element.next = Some(before_this);
+    this_element.previous = before.previous;
+
+    before.previous = Some(elem);
+
+    this_element_store.set(this_element);
+    before_store.set(before);
+}
+
+fn add_after_element(store: &Store, elem: ObjectKey, after_this: ObjectKey) {
+    assert_ne!(elem, after_this);
+
+    let this_element_store = &store.get_object(elem).z_order;
+    let mut this_element = this_element_store.get();
+
+    let after_store = &store.get_object(after_this).z_order;
+    let mut after = after_store.get();
+
+    if let Some(next) = after.next {
+        let neighbour_left_store = &store.get_object(next).z_order;
+        let mut neighbour_right = neighbour_left_store.get();
+        neighbour_right.previous = Some(elem);
+        neighbour_left_store.set(neighbour_right);
+    }
+
+    this_element.previous = Some(after_this);
+    this_element.next = after.next;
+
+    after.next = Some(elem);
+
+    this_element_store.set(this_element);
+    after_store.set(after);
+}
+
+fn move_before(store: &Store, source: ObjectKey, before_this: ObjectKey) {
+    assert_ne!(source, before_this);
+
+    remove_from_linked_list(store, source);
+    add_before_element(store, source, before_this);
+}
+
+fn move_after(store: &Store, source: ObjectKey, after_this: ObjectKey) {
+    assert_ne!(source, after_this);
+
+    remove_from_linked_list(store, source);
+    add_after_element(store, source, after_this);
+}
+
+impl Object<'_> {
+    pub fn set_z(&mut self, z_index: i32) -> &mut Self {
+        let my_object = &self.store.get_object(self.me);
+
+        let order = z_index.cmp(&my_object.z_index.get());
+
+        match order {
+            core::cmp::Ordering::Equal => {}
+            core::cmp::Ordering::Less => {
+                let mut previous_index = self.me;
+                let mut current_index = self.me;
+                while self.store.get_object(current_index).z_index.get() > z_index {
+                    previous_index = current_index;
+                    let previous = self.store.get_object(current_index).z_order.get().previous;
+                    if let Some(previous) = previous {
+                        current_index = previous;
+                    } else {
+                        break;
+                    }
+                }
+                if previous_index != self.me {
+                    move_before(self.store, self.me, previous_index);
+                }
+            }
+            core::cmp::Ordering::Greater => {
+                let mut previous_index = self.me;
+                let mut current_index = self.me;
+                while self.store.get_object(current_index).z_index.get() < z_index {
+                    previous_index = current_index;
+                    let next = self.store.get_object(current_index).z_order.get().next;
+                    if let Some(next) = next {
+                        current_index = next;
+                    } else {
+                        break;
+                    }
+                }
+                if previous_index != self.me {
+                    move_after(self.store, self.me, previous_index);
+                }
+            }
+        }
+
+        my_object.z_index.set(z_index);
+
+        self
+    }
+
+    fn object(&mut self) -> &mut UnmanagedObject {
+        unsafe { &mut *self.store.get_object(self.me).object.get() }
+    }
+
+    fn object_shared(&self) -> &UnmanagedObject {
+        unsafe { &*self.store.get_object(self.me).object.get() }
+    }
+
+    #[must_use]
+    pub fn is_visible(&self) -> bool {
+        self.object_shared().is_visible()
+    }
+
+    pub fn show(&mut self) -> &mut Self {
+        self.object().show();
+
+        self
+    }
+
+    pub fn show_affine(&mut self, affine_mode: AffineMode) -> &mut Self {
+        self.object().show_affine(affine_mode);
+
+        self
+    }
+
+    pub fn set_hflip(&mut self, flip: bool) -> &mut Self {
+        self.object().set_hflip(flip);
+
+        self
+    }
+
+    pub fn set_vflip(&mut self, flip: bool) -> &mut Self {
+        self.object().set_vflip(flip);
+
+        self
+    }
+
+    pub fn set_x(&mut self, x: u16) -> &mut Self {
+        self.object().set_x(x);
+
+        self
+    }
+
+    pub fn set_priority(&mut self, priority: Priority) -> &mut Self {
+        self.object().set_priority(priority);
+
+        self
+    }
+
+    pub fn hide(&mut self) -> &mut Self {
+        self.object().hide();
+
+        self
+    }
+
+    pub fn set_y(&mut self, y: u16) -> &mut Self {
+        self.object().set_y(y);
+
+        self
+    }
+
+    pub fn set_position(&mut self, position: Vector2D<i32>) -> &mut Self {
+        self.object().set_position(position);
+
+        self
+    }
+
+    pub fn set_sprite(&mut self, sprite: SpriteVram) -> &mut Self {
+        self.object().set_sprite(sprite);
+
+        self
+    }
+}

agb/src/display/object/sprites.rs

@@ -0,0 +1,7 @@
+mod sprite;
+mod sprite_allocator;
+
+const BYTES_PER_TILE_4BPP: usize = 32;
+
+pub use sprite::{include_aseprite, Graphics, Size, Sprite, Tag, TagMap};
+pub use sprite_allocator::{DynamicSprite, SpriteVram, StaticSpriteLoader};

agb/src/display/object/sprites/sprite.rs

@@ -0,0 +1,369 @@
+use core::{alloc::Layout, slice};
+
+use crate::display::palette16::Palette16;
+
+use super::BYTES_PER_TILE_4BPP;
+
+/// Sprite data. Refers to the palette, pixel data, and the size of the sprite.
+pub struct Sprite {
+    pub(crate) palette: &'static Palette16,
+    pub(crate) data: &'static [u8],
+    pub(crate) size: Size,
+}
+
+impl Sprite {
+    #[doc(hidden)]
+    /// Creates a sprite from it's constituent data, used internally by
+    /// [include_aseprite] and should generally not be used outside it.
+    ///
+    /// # Safety
+    /// The data should be aligned to a 2 byte boundary
+    #[must_use]
+    pub const unsafe fn new(palette: &'static Palette16, data: &'static [u8], size: Size) -> Self {
+        Self {
+            palette,
+            data,
+            size,
+        }
+    }
+
+    #[must_use]
+    pub fn size(&self) -> Size {
+        self.size
+    }
+}
+
+/// The sizes of sprite supported by the GBA.
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+#[allow(missing_docs)]
+pub enum Size {
+    // stored as attr0 attr1
+    S8x8 = 0b00_00,
+    S16x16 = 0b00_01,
+    S32x32 = 0b00_10,
+    S64x64 = 0b00_11,
+
+    S16x8 = 0b01_00,
+    S32x8 = 0b01_01,
+    S32x16 = 0b01_10,
+    S64x32 = 0b01_11,
+
+    S8x16 = 0b10_00,
+    S8x32 = 0b10_01,
+    S16x32 = 0b10_10,
+    S32x64 = 0b10_11,
+}
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! align_bytes {
+    ($align_ty:ty, $data:literal) => {{
+        #[repr(C)] // guarantee 'bytes' comes after '_align'
+        struct AlignedAs<Align, Bytes: ?Sized> {
+            pub _align: [Align; 0],
+            pub bytes: Bytes,
+        }
+
+        const ALIGNED: &AlignedAs<$align_ty, [u8]> = &AlignedAs {
+            _align: [],
+            bytes: *$data,
+        };
+
+        &ALIGNED.bytes
+    }};
+}
+
+/// Includes sprites found in the referenced aseprite files. Can include
+/// multiple at once and optimises palettes of all included in the single call
+/// together. See [Size] for supported sizes. Returns a reference to [Graphics].
+///
+/// ```rust,no_run
+/// # #![no_std]
+/// # #![no_main]
+/// # use agb::{display::object::Graphics, include_aseprite};
+/// const GRAPHICS: &Graphics = include_aseprite!(
+///     "examples/gfx/boss.aseprite",
+///     "examples/gfx/objects.aseprite"
+/// );
+/// ```
+/// The tags from the aseprite file are included so you can refer to sprites by
+/// name in code. You should ensure tags are unique as this is not enforced by
+/// aseprite.
+///
+#[macro_export]
+macro_rules! include_aseprite {
+    ($($aseprite_path: expr),*) => {{
+        use $crate::display::object::{Size, Sprite, Tag, TagMap, Graphics};
+        use $crate::display::palette16::Palette16;
+        use $crate::align_bytes;
+
+        $crate::include_aseprite_inner!($($aseprite_path),*);
+
+        &Graphics::new(SPRITES, TAGS)
+    }};
+}
+
+pub use include_aseprite;
+
+/// Stores sprite and tag data returned by [include_aseprite].
+pub struct Graphics {
+    sprites: &'static [Sprite],
+    tag_map: &'static TagMap,
+}
+
+impl Graphics {
+    #[doc(hidden)]
+    /// Creates graphics data from sprite data and a tag_map. This is used
+    /// internally by [include_aseprite] and would be otherwise difficult to
+    /// use.
+    #[must_use]
+    pub const fn new(sprites: &'static [Sprite], tag_map: &'static TagMap) -> Self {
+        Self { sprites, tag_map }
+    }
+    #[must_use]
+    /// Gets the tag map from the aseprite files. This allows reference to
+    /// sprite sequences by name.
+    pub const fn tags(&self) -> &TagMap {
+        self.tag_map
+    }
+    /// Gets a big list of the sprites themselves. Using tags is often easier.
+    #[must_use]
+    pub const fn sprites(&self) -> &[Sprite] {
+        self.sprites
+    }
+}
+
+/// Stores aseprite tags. Can be used to refer to animation sequences by name.
+/// ```rust,no_run
+/// # #![no_std]
+/// # #![no_main]
+/// # use agb::{display::object::{Graphics, Tag}, include_aseprite};
+/// const GRAPHICS: &Graphics = include_aseprite!(
+///     "examples/gfx/boss.aseprite",
+///     "examples/gfx/objects.aseprite"
+/// );
+///
+/// const EMU_WALK: &Tag = GRAPHICS.tags().get("emu-walk");
+/// ```
+/// This being the whole animation associated with the walk sequence of the emu.
+/// See [Tag] for details on how to use this.
+pub struct TagMap {
+    tags: &'static [(&'static str, Tag)],
+}
+
+const fn const_byte_compare(a: &[u8], b: &[u8]) -> bool {
+    if a.len() != b.len() {
+        return false;
+    }
+
+    let mut i = 0;
+    while i < a.len() {
+        if a[i] != b[i] {
+            return false;
+        }
+        i += 1;
+    }
+    true
+}
+
+impl TagMap {
+    #[doc(hidden)]
+    /// Creates a new tag map from (name, Tag) pairs. Used internally by
+    /// [include_aseprite] and should not really be used outside of it.
+    #[must_use]
+    pub const fn new(tags: &'static [(&'static str, Tag)]) -> TagMap {
+        Self { tags }
+    }
+
+    #[doc(hidden)]
+    /// Attempts to get a tag. Generally should not be used.
+    #[must_use]
+    pub const fn try_get(&'static self, tag: &str) -> Option<&'static Tag> {
+        let mut i = 0;
+        while i < self.tags.len() {
+            let s = self.tags[i].0;
+            if const_byte_compare(s.as_bytes(), tag.as_bytes()) {
+                return Some(&self.tags[i].1);
+            }
+
+            i += 1;
+        }
+
+        None
+    }
+
+    /// Gets a tag associated with the name. A tag in aseprite refers to a
+    /// sequence of sprites with some metadata for how to animate it. You should
+    /// call this in a constant context so it is evaluated at compile time. It
+    /// is inefficient to call this elsewhere.
+    /// ```rust,no_run
+    /// # #![no_std]
+    /// # #![no_main]
+    /// # use agb::{display::object::{Graphics, Tag}, include_aseprite};
+    /// const GRAPHICS: &Graphics = include_aseprite!(
+    ///     "examples/gfx/boss.aseprite",
+    ///     "examples/gfx/objects.aseprite"
+    /// );
+    ///
+    /// const EMU_WALK: &Tag = GRAPHICS.tags().get("emu-walk");
+    /// ```
+    ///
+    /// See [Tag] for more details.
+    #[must_use]
+    pub const fn get(&'static self, tag: &str) -> &'static Tag {
+        let t = self.try_get(tag);
+        match t {
+            Some(t) => t,
+            None => panic!("The requested tag does not exist"),
+        }
+    }
+
+    /// Takes an iterator over all the tags in the map. Not generally useful.
+    pub fn values(&self) -> impl Iterator<Item = &'static Tag> {
+        self.tags.iter().map(|x| &x.1)
+    }
+}
+
+#[derive(Clone, Copy)]
+enum Direction {
+    Forward,
+    Backward,
+    PingPong,
+}
+
+impl Direction {
+    const fn from_usize(a: usize) -> Self {
+        match a {
+            0 => Direction::Forward,
+            1 => Direction::Backward,
+            2 => Direction::PingPong,
+            _ => panic!("Invalid direction, this is a bug in image converter or agb"),
+        }
+    }
+}
+
+/// A sequence of sprites from aseprite.
+pub struct Tag {
+    sprites: *const Sprite,
+    len: usize,
+    direction: Direction,
+}
+
+impl Tag {
+    /// The individual sprites that make up the animation themselves.
+    #[must_use]
+    pub fn sprites(&self) -> &'static [Sprite] {
+        unsafe { slice::from_raw_parts(self.sprites, self.len) }
+    }
+
+    /// A single sprite referred to by index in the animation sequence.
+    #[must_use]
+    pub const fn sprite(&self, idx: usize) -> &'static Sprite {
+        if idx >= self.len {
+            panic!("out of bounds access to sprite");
+        }
+        unsafe { &*self.sprites.add(idx) }
+    }
+
+    /// A sprite that follows the animation sequence. For instance, in aseprite
+    /// tags can be specified to animate:
+    /// * Forward
+    /// * Backward
+    /// * Ping pong
+    ///
+    /// This takes the animation type in account and returns the correct sprite
+    /// following these requirements.
+    #[inline]
+    #[must_use]
+    pub fn animation_sprite(&self, idx: usize) -> &'static Sprite {
+        let len_sub_1 = self.len - 1;
+        match self.direction {
+            Direction::Forward => self.sprite(idx % self.len),
+            Direction::Backward => self.sprite(len_sub_1 - (idx % self.len)),
+            Direction::PingPong => self.sprite(
+                (((idx + len_sub_1) % (len_sub_1 * 2)) as isize - len_sub_1 as isize)
+                    .unsigned_abs(),
+            ),
+        }
+    }
+
+    #[doc(hidden)]
+    /// Creates a new sprite from it's constituent parts. Used internally by
+    /// [include_aseprite] and should generally not be used elsewhere.
+    #[must_use]
+    pub const fn new(sprites: &'static [Sprite], from: usize, to: usize, direction: usize) -> Self {
+        assert!(from <= to);
+        assert!(to < sprites.len());
+        Self {
+            sprites: &sprites[from] as *const Sprite,
+            len: to - from + 1,
+            direction: Direction::from_usize(direction),
+        }
+    }
+}
+
+impl Size {
+    pub(crate) const fn number_of_tiles(self) -> usize {
+        match self {
+            Size::S8x8 => 1,
+            Size::S16x16 => 4,
+            Size::S32x32 => 16,
+            Size::S64x64 => 64,
+            Size::S16x8 => 2,
+            Size::S32x8 => 4,
+            Size::S32x16 => 8,
+            Size::S64x32 => 32,
+            Size::S8x16 => 2,
+            Size::S8x32 => 4,
+            Size::S16x32 => 8,
+            Size::S32x64 => 32,
+        }
+    }
+    pub(crate) const fn shape_size(self) -> (u16, u16) {
+        (self as u16 >> 2, self as u16 & 0b11)
+    }
+
+    pub(crate) fn layout(self) -> Layout {
+        Layout::from_size_align(self.number_of_tiles() * BYTES_PER_TILE_4BPP, 8).unwrap()
+    }
+
+    #[must_use]
+    /// Creates a size from width and height in pixels, panics if the width and
+    /// height is not representable by GBA sprites.
+    pub const fn from_width_height(width: usize, height: usize) -> Self {
+        match (width, height) {
+            (8, 8) => Size::S8x8,
+            (16, 16) => Size::S16x16,
+            (32, 32) => Size::S32x32,
+            (64, 64) => Size::S64x64,
+            (16, 8) => Size::S16x8,
+            (32, 8) => Size::S32x8,
+            (32, 16) => Size::S32x16,
+            (64, 32) => Size::S64x32,
+            (8, 16) => Size::S8x16,
+            (8, 32) => Size::S8x32,
+            (16, 32) => Size::S16x32,
+            (32, 64) => Size::S32x64,
+            (_, _) => panic!("Bad width and height!"),
+        }
+    }
+
+    #[must_use]
+    /// Returns the width and height of the size in pixels.
+    pub const fn to_width_height(self) -> (usize, usize) {
+        match self {
+            Size::S8x8 => (8, 8),
+            Size::S16x16 => (16, 16),
+            Size::S32x32 => (32, 32),
+            Size::S64x64 => (64, 64),
+            Size::S16x8 => (16, 8),
+            Size::S32x8 => (32, 8),
+            Size::S32x16 => (32, 16),
+            Size::S64x32 => (64, 32),
+            Size::S8x16 => (8, 16),
+            Size::S8x32 => (8, 32),
+            Size::S16x32 => (16, 32),
+            Size::S32x64 => (32, 64),
+        }
+    }
+}

agb/src/display/object/sprites/sprite_allocator.rs

@@ -0,0 +1,288 @@
+use core::ptr::NonNull;
+
+use alloc::rc::{Rc, Weak};
+
+use crate::{
+    agb_alloc::{block_allocator::BlockAllocator, bump_allocator::StartEnd},
+    display::palette16::Palette16,
+    hash_map::HashMap,
+};
+
+use super::{
+    sprite::{Size, Sprite},
+    BYTES_PER_TILE_4BPP,
+};
+
+const PALETTE_SPRITE: usize = 0x0500_0200;
+const TILE_SPRITE: usize = 0x06010000;
+
+static SPRITE_ALLOCATOR: BlockAllocator = unsafe {
+    BlockAllocator::new(StartEnd {
+        start: || TILE_SPRITE,
+        end: || TILE_SPRITE + 1024 * 8 * 4,
+    })
+};
+
+static PALETTE_ALLOCATOR: BlockAllocator = unsafe {
+    BlockAllocator::new(StartEnd {
+        start: || PALETTE_SPRITE,
+        end: || PALETTE_SPRITE + 0x200,
+    })
+};
+
+/// The Sprite Id is a thin wrapper around the pointer to the sprite in
+/// rom and is therefore a unique identifier to a sprite
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+struct SpriteId(usize);
+
+impl SpriteId {
+    fn from_static_sprite(sprite: &'static Sprite) -> SpriteId {
+        SpriteId(sprite as *const _ as usize)
+    }
+}
+
+/// The palette id is a thin wrapper around the pointer to the palette in rom
+/// and is therefore a unique reference to a palette
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+struct PaletteId(usize);
+
+impl PaletteId {
+    fn from_static_palette(palette: &'static Palette16) -> PaletteId {
+        PaletteId(palette as *const _ as usize)
+    }
+}
+
+/// This holds loading of static sprites and palettes.
+pub struct StaticSpriteLoader {
+    static_palette_map: HashMap<PaletteId, Weak<PaletteVramData>>,
+    static_sprite_map: HashMap<SpriteId, Weak<SpriteVramData>>,
+}
+
+#[derive(Clone, Copy, Debug)]
+struct Location(usize);
+
+impl Location {
+    fn from_sprite_ptr(d: NonNull<u8>) -> Self {
+        Self(((d.as_ptr() as usize) - TILE_SPRITE) / BYTES_PER_TILE_4BPP)
+    }
+    fn from_palette_ptr(d: NonNull<u8>) -> Self {
+        Self((d.as_ptr() as usize - PALETTE_SPRITE) / Palette16::layout().size())
+    }
+    fn as_palette_ptr(self) -> *mut u8 {
+        (self.0 * Palette16::layout().size() + PALETTE_SPRITE) as *mut u8
+    }
+    fn as_sprite_ptr(self) -> *mut u8 {
+        (self.0 * BYTES_PER_TILE_4BPP + TILE_SPRITE) as *mut u8
+    }
+}
+
+#[derive(Debug)]
+struct PaletteVramData {
+    location: Location,
+}
+
+#[derive(Debug)]
+pub struct PaletteVram {
+    data: Rc<PaletteVramData>,
+}
+
+impl PaletteVram {
+    fn new(palette: &Palette16) -> Option<PaletteVram> {
+        let allocated = unsafe { PALETTE_ALLOCATOR.alloc(Palette16::layout()) }?;
+
+        unsafe {
+            allocated
+                .as_ptr()
+                .cast::<u16>()
+                .copy_from_nonoverlapping(palette.colours.as_ptr(), palette.colours.len());
+        }
+
+        Some(PaletteVram {
+            data: Rc::new(PaletteVramData {
+                location: Location::from_palette_ptr(allocated),
+            }),
+        })
+    }
+}
+
+#[derive(Debug)]
+struct SpriteVramData {
+    location: Location,
+    size: Size,
+    palette: PaletteVram,
+}
+
+impl Drop for SpriteVramData {
+    fn drop(&mut self) {
+        unsafe { SPRITE_ALLOCATOR.dealloc(self.location.as_sprite_ptr(), self.size.layout()) }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct SpriteVram {
+    data: Rc<SpriteVramData>,
+}
+
+impl SpriteVram {
+    fn new(data: &[u8], size: Size, palette: PaletteVram) -> Option<SpriteVram> {
+        let allocated = unsafe { SPRITE_ALLOCATOR.alloc(size.layout()) }?;
+        unsafe {
+            allocated
+                .as_ptr()
+                .copy_from_nonoverlapping(data.as_ptr(), data.len());
+        }
+        Some(SpriteVram {
+            data: Rc::new(SpriteVramData {
+                location: Location::from_sprite_ptr(allocated),
+                size,
+                palette,
+            }),
+        })
+    }
+
+    pub(crate) fn location(&self) -> u16 {
+        self.data.location.0 as u16
+    }
+
+    pub(crate) fn size(&self) -> Size {
+        self.data.size
+    }
+
+    pub(crate) fn palette_location(&self) -> u16 {
+        self.data.palette.data.location.0 as u16
+    }
+}
+
+impl StaticSpriteLoader {
+    fn create_sprite_no_insert(
+        palette_map: &mut HashMap<PaletteId, Weak<PaletteVramData>>,
+        sprite: &'static Sprite,
+    ) -> Option<(Weak<SpriteVramData>, SpriteVram)> {
+        let palette = Self::try_get_vram_palette_asoc(palette_map, sprite.palette)?;
+
+        let sprite = SpriteVram::new(sprite.data, sprite.size, palette)?;
+        Some((Rc::downgrade(&sprite.data), sprite))
+    }
+
+    fn try_get_vram_palette_asoc(
+        palette_map: &mut HashMap<PaletteId, Weak<PaletteVramData>>,
+        palette: &'static Palette16,
+    ) -> Option<PaletteVram> {
+        let id = PaletteId::from_static_palette(palette);
+        Some(match palette_map.entry(id) {
+            crate::hash_map::Entry::Occupied(mut entry) => match entry.get().upgrade() {
+                Some(data) => PaletteVram { data },
+                None => {
+                    let pv = PaletteVram::new(palette)?;
+                    entry.insert(Rc::downgrade(&pv.data));
+                    pv
+                }
+            },
+            crate::hash_map::Entry::Vacant(entry) => {
+                let pv = PaletteVram::new(palette)?;
+                entry.insert(Rc::downgrade(&pv.data));
+                pv
+            }
+        })
+    }
+
+    pub fn try_get_vram_sprite(&mut self, sprite: &'static Sprite) -> Option<SpriteVram> {
+        // check if we already have the sprite in vram
+
+        let id = SpriteId::from_static_sprite(sprite);
+
+        Some(match self.static_sprite_map.entry(id) {
+            crate::hash_map::Entry::Occupied(mut entry) => match entry.get().upgrade() {
+                Some(data) => SpriteVram { data },
+                None => {
+                    let (weak, vram) =
+                        Self::create_sprite_no_insert(&mut self.static_palette_map, sprite)?;
+                    entry.insert(weak);
+                    vram
+                }
+            },
+            crate::hash_map::Entry::Vacant(entry) => {
+                let (weak, vram) =
+                    Self::create_sprite_no_insert(&mut self.static_palette_map, sprite)?;
+                entry.insert(weak);
+                vram
+            }
+        })
+    }
+
+    pub fn try_get_vram_palette(&mut self, palette: &'static Palette16) -> Option<PaletteVram> {
+        Self::try_get_vram_palette_asoc(&mut self.static_palette_map, palette)
+    }
+
+    pub fn get_vram_sprite(&mut self, sprite: &'static Sprite) -> SpriteVram {
+        self.try_get_vram_sprite(sprite)
+            .expect("no free sprite slots")
+    }
+
+    pub fn get_vram_palette(&mut self, palette: &'static Palette16) -> PaletteVram {
+        self.try_get_vram_palette(palette)
+            .expect("no free palette slots")
+    }
+
+    pub(crate) fn new() -> Self {
+        Self {
+            static_palette_map: HashMap::new(),
+            static_sprite_map: HashMap::new(),
+        }
+    }
+
+    fn gc(&mut self) {
+        self.static_sprite_map
+            .retain(|_, v| Weak::strong_count(v) != 0);
+        self.static_palette_map
+            .retain(|_, v| Weak::strong_count(v) != 0);
+    }
+}
+
+impl Default for StaticSpriteLoader {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// Sprite data that can be used to create sprites in vram.
+pub struct DynamicSprite<'a> {
+    data: &'a [u8],
+    size: Size,
+}
+
+impl DynamicSprite<'_> {
+    #[must_use]
+    /// Creates a new dynamic sprite from underlying bytes. Note that despite
+    /// being an array of u8, this must be aligned to at least a 2 byte
+    /// boundary.
+    pub fn new(data: &[u8], size: Size) -> DynamicSprite {
+        let ptr = &data[0] as *const _ as usize;
+        if ptr % 2 != 0 {
+            panic!("data is not aligned to a 2 byte boundary");
+        }
+        if data.len() != size.number_of_tiles() * BYTES_PER_TILE_4BPP {
+            panic!(
+                "data is not of expected length, got {} expected {}",
+                data.len(),
+                size.number_of_tiles() * BYTES_PER_TILE_4BPP
+            );
+        }
+        DynamicSprite { data, size }
+    }
+
+    #[must_use]
+    /// Tries to copy the sprite to vram to be used to set object sprites.
+    /// Returns None if there is no room in sprite vram.
+    pub fn try_vram(&self, palette: PaletteVram) -> Option<SpriteVram> {
+        SpriteVram::new(self.data, self.size, palette)
+    }
+
+    #[must_use]
+    /// Tries to copy the sprite to vram to be used to set object sprites.
+    /// Panics if there is no room in sprite vram.
+    pub fn to_vram(&self, palette: PaletteVram) -> SpriteVram {
+        self.try_vram(palette)
+            .expect("No slot for sprite available")
+    }
+}

agb/src/display/object/unmanaged.rs

@@ -0,0 +1,5 @@
+mod attributes;
+mod object;
+
+pub use attributes::AffineMode;
+pub use object::{OAMIterator, OAMSlot, UnmanagedOAM, UnmanagedObject};

agb/src/display/object/unmanaged/attributes.rs

@@ -0,0 +1,204 @@
+use modular_bitfield::BitfieldSpecifier;
+
+use crate::display::Priority;
+
+use self::attributes::{
+    ObjectAttribute0, ObjectAttribute1Affine, ObjectAttribute1Standard, ObjectAttribute2,
+};
+
+#[derive(PartialEq, Eq, Debug)]
+pub struct Attributes {
+    a0: ObjectAttribute0,
+    a1s: ObjectAttribute1Standard,
+    a1a: ObjectAttribute1Affine,
+    a2: ObjectAttribute2,
+}
+
+impl Default for Attributes {
+    fn default() -> Self {
+        Self {
+            a0: ObjectAttribute0::from_bytes([0b01, 0]),
+            a1s: Default::default(),
+            a1a: Default::default(),
+            a2: Default::default(),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
+pub enum AffineMode {
+    Affine = 1,
+    AffineDouble = 3,
+}
+
+impl Attributes {
+    pub fn bytes(&self) -> [u8; 6] {
+        let mode = self.a0.object_mode();
+        let attrs = match mode {
+            ObjectMode::Normal => [
+                self.a0.into_bytes(),
+                self.a1s.into_bytes(),
+                self.a2.into_bytes(),
+            ],
+            _ => [
+                self.a0.into_bytes(),
+                self.a1a.into_bytes(),
+                self.a2.into_bytes(),
+            ],
+        };
+
+        // Safety: length and alignment are the same, and every possible value is valid
+        unsafe { core::mem::transmute(attrs) }
+    }
+
+    pub fn is_visible(&self) -> bool {
+        self.a0.object_mode() != ObjectMode::Disabled
+    }
+
+    pub fn show(&mut self) -> &mut Self {
+        self.a0.set_object_mode(ObjectMode::Normal);
+
+        self
+    }
+
+    pub fn show_affine(&mut self, affine_mode: AffineMode) -> &mut Self {
+        self.a0.set_object_mode(match affine_mode {
+            AffineMode::Affine => ObjectMode::Affine,
+            AffineMode::AffineDouble => ObjectMode::AffineDouble,
+        });
+
+        self
+    }
+
+    pub fn set_hflip(&mut self, flip: bool) -> &mut Self {
+        self.a1s.set_horizontal_flip(flip);
+
+        self
+    }
+
+    pub fn set_vflip(&mut self, flip: bool) -> &mut Self {
+        self.a1s.set_vertical_flip(flip);
+
+        self
+    }
+
+    pub fn set_x(&mut self, x: u16) -> &mut Self {
+        self.a1a.set_x(x.rem_euclid(1 << 9));
+        self.a1s.set_x(x.rem_euclid(1 << 9));
+
+        self
+    }
+
+    pub fn set_priority(&mut self, priority: Priority) -> &mut Self {
+        self.a2.set_priority(priority);
+
+        self
+    }
+
+    pub fn hide(&mut self) -> &mut Self {
+        self.a0.set_object_mode(ObjectMode::Disabled);
+
+        self
+    }
+
+    pub fn set_y(&mut self, y: u16) -> &mut Self {
+        self.a0.set_y(y as u8);
+
+        self
+    }
+
+    pub fn set_palette(&mut self, palette_id: u16) -> &mut Self {
+        self.a2.set_palette_bank(palette_id as u8);
+
+        self
+    }
+
+    pub fn set_affine_matrix(&mut self, affine_matrix_id: u16) -> &mut Self {
+        self.a1a.set_affine_index(affine_matrix_id as u8);
+
+        self
+    }
+
+    pub fn set_sprite(&mut self, sprite_id: u16, shape: u16, size: u16) -> &mut Self {
+        self.a2.set_tile_index(sprite_id);
+        self.a1a.set_size(size as u8);
+        self.a1s.set_size(size as u8);
+        self.a0.set_shape(shape as u8);
+
+        self
+    }
+}
+
+#[derive(BitfieldSpecifier, Clone, Copy, Debug, PartialEq, Eq)]
+enum ObjectMode {
+    Normal,
+    Affine,
+    Disabled,
+    AffineDouble,
+}
+
+#[derive(BitfieldSpecifier, Clone, Copy, Debug, PartialEq, Eq)]
+#[bits = 2]
+enum GraphicsMode {
+    Normal,
+    AlphaBlending,
+    Window,
+}
+
+#[derive(BitfieldSpecifier, Clone, Copy, Debug, PartialEq, Eq)]
+enum ColourMode {
+    Four,
+    Eight,
+}
+
+// this mod is not public, so the internal parts don't need documenting.
+#[allow(dead_code)]
+#[allow(clippy::all)]
+#[allow(clippy::map_unwrap_or)]
+mod attributes {
+    use modular_bitfield::{
+        bitfield,
+        specifiers::{B10, B2, B3, B4, B5, B8, B9},
+    };
+
+    use crate::display::Priority;
+
+    use super::*;
+    #[bitfield]
+    #[derive(Clone, Copy, PartialEq, Eq, Debug, Default)]
+    pub(super) struct ObjectAttribute0 {
+        pub y: B8,
+        pub object_mode: ObjectMode,
+        pub graphics_mode: GraphicsMode,
+        pub mosaic: bool,
+        pub colour_mode: ColourMode,
+        pub shape: B2,
+    }
+
+    #[bitfield]
+    #[derive(Clone, Copy, PartialEq, Eq, Debug, Default)]
+    pub(super) struct ObjectAttribute1Standard {
+        pub x: B9,
+        #[skip]
+        __: B3,
+        pub horizontal_flip: bool,
+        pub vertical_flip: bool,
+        pub size: B2,
+    }
+
+    #[bitfield]
+    #[derive(Clone, Copy, PartialEq, Eq, Debug, Default)]
+    pub(super) struct ObjectAttribute1Affine {
+        pub x: B9,
+        pub affine_index: B5,
+        pub size: B2,
+    }
+
+    #[bitfield]
+    #[derive(Clone, Copy, PartialEq, Eq, Debug, Default)]
+    pub(super) struct ObjectAttribute2 {
+        pub tile_index: B10,
+        pub priority: Priority,
+        pub palette_bank: B4,
+    }
+}

agb/src/display/object/unmanaged/object.rs

@@ -0,0 +1,187 @@
+use core::{cell::UnsafeCell, marker::PhantomData};
+
+use agb_fixnum::Vector2D;
+
+use crate::display::{
+    object::{sprites::SpriteVram, OBJECT_ATTRIBUTE_MEMORY},
+    Priority,
+};
+
+use super::attributes::{AffineMode, Attributes};
+
+pub struct UnmanagedOAM<'gba> {
+    phantom: PhantomData<&'gba ()>,
+}
+
+pub struct OAMIterator<'oam> {
+    phantom: PhantomData<&'oam ()>,
+    index: usize,
+}
+
+pub struct OAMSlot<'oam> {
+    phantom: PhantomData<&'oam ()>,
+    slot: usize,
+}
+
+impl OAMSlot<'_> {
+    pub fn set(&mut self, object: &UnmanagedObject) {
+        self.set_bytes(object.attributes.bytes());
+
+        // SAFETY: This is called here and in set_sprite, neither of which call the other.
+        let sprites = unsafe { &mut *object.sprites.get() };
+
+        sprites.previous_sprite = Some(sprites.sprite.clone());
+    }
+
+    fn set_bytes(&mut self, bytes: [u8; 6]) {
+        unsafe {
+            let address = (OBJECT_ATTRIBUTE_MEMORY as *mut u8).add(self.slot * 8);
+            address.copy_from_nonoverlapping(bytes.as_ptr(), bytes.len());
+        }
+    }
+}
+
+impl<'oam> Iterator for OAMIterator<'oam> {
+    type Item = OAMSlot<'oam>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let idx = self.index;
+        self.index += 1;
+
+        if idx >= 128 {
+            None
+        } else {
+            Some(OAMSlot {
+                phantom: PhantomData,
+                slot: idx,
+            })
+        }
+    }
+}
+
+impl UnmanagedOAM<'_> {
+    pub fn iter(&mut self) -> OAMIterator<'_> {
+        OAMIterator {
+            phantom: PhantomData,
+            index: 0,
+        }
+    }
+
+    pub(crate) fn new() -> Self {
+        Self {
+            phantom: PhantomData,
+        }
+    }
+
+    pub fn clear_from(&self, from: usize) {
+        if from >= 128 {
+            return;
+        }
+
+        for i in from..128 {
+            unsafe {
+                let ptr = (OBJECT_ATTRIBUTE_MEMORY as *mut u16).add(i * 4);
+                ptr.write_volatile(0b10 << 8);
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+struct VramSprites {
+    sprite: SpriteVram,
+    previous_sprite: Option<SpriteVram>,
+}
+
+#[derive(Debug)]
+pub struct UnmanagedObject {
+    attributes: Attributes,
+    sprites: UnsafeCell<VramSprites>,
+}
+
+impl UnmanagedObject {
+    #[must_use]
+    pub fn new(sprite: SpriteVram) -> Self {
+        Self {
+            attributes: Attributes::default(),
+            sprites: UnsafeCell::new(VramSprites {
+                sprite,
+                previous_sprite: None,
+            }),
+        }
+    }
+
+    pub fn is_visible(&self) -> bool {
+        self.attributes.is_visible()
+    }
+
+    pub fn show(&mut self) -> &mut Self {
+        self.attributes.show();
+
+        self
+    }
+
+    pub fn show_affine(&mut self, affine_mode: AffineMode) -> &mut Self {
+        self.attributes.show_affine(affine_mode);
+
+        self
+    }
+
+    pub fn set_hflip(&mut self, flip: bool) -> &mut Self {
+        self.attributes.set_hflip(flip);
+
+        self
+    }
+
+    pub fn set_vflip(&mut self, flip: bool) -> &mut Self {
+        self.attributes.set_vflip(flip);
+
+        self
+    }
+
+    pub fn set_x(&mut self, x: u16) -> &mut Self {
+        self.attributes.set_x(x);
+
+        self
+    }
+
+    pub fn set_priority(&mut self, priority: Priority) -> &mut Self {
+        self.attributes.set_priority(priority);
+
+        self
+    }
+
+    pub fn hide(&mut self) -> &mut Self {
+        self.attributes.hide();
+
+        self
+    }
+
+    pub fn set_y(&mut self, y: u16) -> &mut Self {
+        self.attributes.set_y(y);
+
+        self
+    }
+
+    pub fn set_position(&mut self, position: Vector2D<i32>) -> &mut Self {
+        self.set_y(position.y.rem_euclid(1 << 9) as u16);
+        self.set_x(position.x.rem_euclid(1 << 9) as u16);
+
+        self
+    }
+
+    pub fn set_sprite(&mut self, sprite: SpriteVram) -> &mut Self {
+        // SAFETY: This is called here and in OAMSlot set, neither of which call the other.
+        let sprites = unsafe { &mut *self.sprites.get() };
+
+        let size = sprite.size();
+        let (shape, size) = size.shape_size();
+
+        self.attributes.set_sprite(sprite.location(), shape, size);
+        self.attributes.set_palette(sprite.palette_location());
+
+        sprites.sprite = sprite;
+
+        self
+    }
+}

agb/src/display/palette16.rs

@@ -1,3 +1,5 @@
+use core::alloc::Layout;
+
 #[repr(C)]
 #[derive(Clone)]
 pub struct Palette16 {
@@ -21,4 +23,8 @@ impl Palette16 {
     pub fn colour(&self, index: usize) -> u16 {
         self.colours[index]
     }
+
+    pub(crate) const fn layout() -> Layout {
+        Layout::new::<Self>()
+    }
 }