copy affine matricies at copy time

agb/src/display/object.rs

@@ -12,8 +12,6 @@ pub use affine::AffineMatrix;
 pub use managed::{OAMManager, Object};
 pub use unmanaged::{AffineMode, OAMIterator, OAMSlot, UnmanagedOAM, UnmanagedObject};
 
-pub(crate) use affine::init_affine;
-
 use super::DISPLAY_CONTROL;
 
 const OBJECT_ATTRIBUTE_MEMORY: usize = 0x0700_0000;

agb/src/display/object/affine.rs

@@ -1,37 +1,63 @@
+use core::cell::Cell;
+
 use alloc::rc::Rc;
 
-use crate::{display::affine::AffineMatrixObject, sync::Static};
+use crate::display::affine::AffineMatrixObject;
 
 use super::OBJECT_ATTRIBUTE_MEMORY;
 
 #[derive(Debug)]
-struct AffineMatrixLocation {
-    location: u16,
+struct AffineMatrixData {
+    frame_count: Cell<u32>,
+    location: Cell<u32>,
+    matrix: AffineMatrixObject,
 }
 
 #[derive(Debug, Clone)]
-pub(crate) struct AffineMatrixVram(Rc<AffineMatrixLocation>);
+pub(crate) struct AffineMatrixVram(Rc<AffineMatrixData>);
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct AffineMatrix {
     location: AffineMatrixVram,
 }
 
 impl AffineMatrix {
-    pub fn new(affine_matrix: AffineMatrixObject) -> Option<AffineMatrix> {
-        let mut matrix = AFFINE_MATRIX_DISTRIBUTOR.get_matrix()?;
-        matrix.write(affine_matrix);
-
-        Some(matrix)
+    #[must_use]
+    pub fn new(affine_matrix: AffineMatrixObject) -> AffineMatrix {
+        AffineMatrix {
+            location: AffineMatrixVram(Rc::new(AffineMatrixData {
+                frame_count: Cell::new(u32::MAX),
+                location: Cell::new(u32::MAX),
+                matrix: affine_matrix,
+            })),
+        }
     }
 
     pub(crate) fn vram(self) -> AffineMatrixVram {
         self.location
     }
+}
 
-    fn write(&mut self, affine_matrix: AffineMatrixObject) {
-        let components = affine_matrix.components();
-        let location = self.location.0.location as usize;
+impl AffineMatrixVram {
+    pub fn frame_count(&self) -> u32 {
+        self.0.frame_count.get()
+    }
+
+    pub fn set_frame_count(&self, frame: u32) {
+        self.0.frame_count.set(frame);
+    }
+
+    pub fn location(&self) -> u32 {
+        self.0.location.get()
+    }
+
+    pub fn set_location(&self, location: u32) {
+        self.0.location.set(location);
+    }
+
+    pub fn write_to_location(&self) {
+        let components = self.0.matrix.components();
+        let location = self.0.location.get() as usize;
         for (idx, component) in components.iter().enumerate() {
             unsafe {
                 (OBJECT_ATTRIBUTE_MEMORY as *mut u16)
@@ -42,74 +68,15 @@ impl AffineMatrix {
     }
 }
 
-impl AffineMatrixVram {
-    pub fn location(&self) -> u16 {
-        self.0.location
-    }
-}
-
-impl Drop for AffineMatrixLocation {
-    fn drop(&mut self) {
-        // safety: obtained via affine matrix distributor
-        unsafe { AFFINE_MATRIX_DISTRIBUTOR.return_matrix(self.location) }
-    }
-}
-
-struct AffineMatrixDistributor {
-    tip: Static<u16>,
-}
-
-static AFFINE_MATRIX_DISTRIBUTOR: AffineMatrixDistributor = AffineMatrixDistributor::new();
-
-pub(crate) unsafe fn init_affine() {
-    AFFINE_MATRIX_DISTRIBUTOR.initialise_affine_matricies();
-}
-
-impl AffineMatrixDistributor {
-    const fn new() -> Self {
-        AffineMatrixDistributor {
-            tip: Static::new(u16::MAX),
-        }
-    }
-
-    unsafe fn initialise_affine_matricies(&self) {
-        for i in 0..32 {
-            let ptr = (OBJECT_ATTRIBUTE_MEMORY as *mut u16).add(i * 16 + 3);
-
-            if i == 31 {
-                // none
-                ptr.write_volatile(u16::MAX);
-            } else {
-                ptr.write_volatile(i as u16 + 1);
-            }
-        }
-
-        self.tip.write(0);
-    }
-
-    fn location_of(affine_matrix_location: u16) -> *mut u16 {
-        unsafe {
-            (OBJECT_ATTRIBUTE_MEMORY as *mut u16).add(affine_matrix_location as usize * 16 + 3)
-        }
-    }
-
-    fn get_matrix(&self) -> Option<AffineMatrix> {
-        let location = self.tip.read();
-        if location == u16::MAX {
-            return None;
-        }
-
-        let next_tip = unsafe { Self::location_of(location).read_volatile() };
-
-        self.tip.write(next_tip);
-
-        Some(AffineMatrix {
-            location: AffineMatrixVram(Rc::new(AffineMatrixLocation { location })),
-        })
-    }
-
-    unsafe fn return_matrix(&self, mat_id: u16) {
-        Self::location_of(mat_id).write_volatile(mat_id);
-        self.tip.write(mat_id);
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test_case]
+    fn niche_optimisation(_gba: &mut crate::Gba) {
+        assert_eq!(
+            core::mem::size_of::<AffineMatrix>(),
+            core::mem::size_of::<Option<AffineMatrix>>()
+        );
     }
 }

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

@@ -6,7 +6,7 @@ use self::attributes::{
     ObjectAttribute0, ObjectAttribute1Affine, ObjectAttribute1Standard, ObjectAttribute2,
 };
 
-#[derive(PartialEq, Eq, Debug, Clone)]
+#[derive(PartialEq, Eq, Debug, Clone, Copy)]
 pub struct Attributes {
     a0: ObjectAttribute0,
     a1s: ObjectAttribute1Standard,
@@ -32,7 +32,7 @@ pub enum AffineMode {
 }
 
 impl Attributes {
-    pub fn bytes(&self) -> [u8; 6] {
+    pub fn bytes(self) -> [u8; 6] {
         let mode = self.a0.object_mode();
         let attrs = match mode {
             ObjectMode::Normal => [
@@ -51,7 +51,7 @@ impl Attributes {
         unsafe { core::mem::transmute(attrs) }
     }
 
-    pub fn is_visible(&self) -> bool {
+    pub fn is_visible(self) -> bool {
         self.a0.object_mode() != ObjectMode::Disabled
     }
 

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

@@ -16,14 +16,14 @@ use super::attributes::{AffineMode, Attributes};
 struct OamFrameModifyables {
     up_to: i32,
     this_frame_sprites: Vec<SpriteVram>,
-    this_frame_affine: Vec<AffineMatrixVram>,
+    frame: u32,
+    affine_matrix_count: u32,
 }
 
 pub struct UnmanagedOAM<'gba> {
     phantom: PhantomData<&'gba ()>,
     frame_data: UnsafeCell<OamFrameModifyables>,
     previous_frame_sprites: Vec<SpriteVram>,
-    previous_frame_affine: Vec<AffineMatrixVram>,
 }
 
 pub struct OAMIterator<'oam> {
@@ -38,16 +38,29 @@ pub struct OAMSlot<'oam> {
 
 impl OAMSlot<'_> {
     pub fn set(&mut self, object: &UnmanagedObject) {
-        self.set_bytes(object.attributes.bytes());
-
+        let mut attributes = object.attributes;
         // SAFETY: This function is not reentrant and we currently hold a mutable borrow of the [UnmanagedOAM].
         let frame_data = unsafe { &mut *self.frame_data.get() };
 
-        frame_data.this_frame_sprites.push(object.sprite.clone());
-        if let Some(affine) = &object.affine_matrix {
-            frame_data.this_frame_affine.push(affine.clone());
+        if let Some(affine_matrix) = &object.affine_matrix {
+            if affine_matrix.frame_count() != frame_data.frame {
+                affine_matrix.set_frame_count(frame_data.frame);
+                assert!(
+                    frame_data.affine_matrix_count <= 32,
+                    "too many affine matricies in one frame"
+                );
+                affine_matrix.set_location(frame_data.affine_matrix_count);
+                frame_data.affine_matrix_count += 1;
+                affine_matrix.write_to_location();
+            }
+
+            attributes.set_affine_matrix(affine_matrix.location() as u16);
         }
 
+        self.set_bytes(attributes.bytes());
+
+        frame_data.this_frame_sprites.push(object.sprite.clone());
+
         frame_data.up_to = self.slot as i32;
     }
 
@@ -96,6 +109,8 @@ impl UnmanagedOAM<'_> {
     pub fn iter(&mut self) -> OAMIterator<'_> {
         let frame_data = self.frame_data.get_mut();
         frame_data.up_to = -1;
+        frame_data.frame = frame_data.frame.wrapping_add(1);
+        frame_data.affine_matrix_count = 0;
 
         // We drain the previous frame sprites here to reuse the Vecs allocation and remove the now unused sprites.
         // Any sprites currently being shown will now be put in the new Vec.
@@ -105,13 +120,6 @@ impl UnmanagedOAM<'_> {
             &mut self.previous_frame_sprites,
         );
 
-        // Drain previous frame affine matricies
-        self.previous_frame_affine.drain(..);
-        core::mem::swap(
-            &mut frame_data.this_frame_affine,
-            &mut self.previous_frame_affine,
-        );
-
         OAMIterator {
             index: 0,
             frame_data: &self.frame_data,
@@ -123,7 +131,6 @@ impl UnmanagedOAM<'_> {
             frame_data: Default::default(),
             phantom: PhantomData,
             previous_frame_sprites: Default::default(),
-            previous_frame_affine: Default::default(),
         }
     }
 }
@@ -221,9 +228,7 @@ impl UnmanagedObject {
 
     pub fn set_affine_matrix(&mut self, affine_matrix: AffineMatrix) -> &mut Self {
         let vram = affine_matrix.vram();
-        let location = vram.location();
         self.affine_matrix = Some(vram);
-        self.attributes.set_affine_matrix(location);
 
         self
     }

agb/src/lib.rs

@@ -236,7 +236,6 @@ impl Gba {
     #[doc(hidden)]
     #[must_use]
     pub unsafe fn new_in_entry() -> Self {
-        display::object::init_affine();
         Self::single_new()
     }