Remove single-instruction helper func

src/display/mod.rs

@@ -334,31 +334,6 @@ impl Display {
         }
     }
 
-    fn get_background_attribute(
-        &self,
-        //tile_index_x: usize,
-        //tile_index_y: usize,
-        vram_offset: usize,
-    ) -> BgMapAttributes {
-        /*
-        let background_map = if self.control & CTRL_BG_TILE_MAP_SELECT != 0 {
-            0x1C00
-        } else {
-            0x1800
-        };
-
-        let vram_offset: usize =
-            background_map + ((tile_index_y as usize) * 32) + tile_index_x as usize;
-            */
-        // Background attributes are only in this memory range.
-        assert!(
-            vram_offset >= 0x1800 && vram_offset < 0x2000,
-            format!("offset: {:04X}", vram_offset)
-        );
-
-        BgMapAttributes(self.vram1[vram_offset])
-    }
-
     pub fn tick(&mut self, ticks: u16) {
         self.status &= 0xFC;
         if self.control & CTRL_LCD_DISPLAY_ENABLE == 0 {
@@ -621,7 +596,7 @@ impl Display {
 
                 // GBC stuff
                 // Get BG map attributes
-                let bg_attribs = self.get_background_attribute(vram_offset);
+                let bg_attribs = BgMapAttributes(self.vram1[vram_offset]);
                 let vram = [&*self.vram0, &*self.vram1][bg_attribs.vram_bank_number()];
 
                 // TODO: Priority
@@ -687,11 +662,7 @@ impl Display {
 
                         // Obtain tile ID in this area
                         let tile_id = self.vram0[vram_offset];
-
+                        let bg_attribs = BgMapAttributes(self.vram1[vram_offset]);
-                        let bg_attribs = self.get_background_attribute(
-                            //tile_index_x as usize, tile_index_y as usize
-                            vram_offset,
-                        );
 
                         // Get BG map attributes
                         let vram = if bg_attribs.vram_bank_number() == 0 {
@@ -700,13 +671,12 @@ impl Display {
                             &*self.vram1
                         };
 
-                        // TODO: Priority
+                        let tile_offset_x = if bg_attribs.horizontal_flip() {
-                        let tile_offset_x = if bg_attribs.vertical_flip() {
                             7 ^ tile_offset_x
                         } else {
                             tile_offset_x
                         };
-                        let tile_offset_y = if bg_attribs.horizontal_flip() {
+                        let tile_offset_y = if bg_attribs.vertical_flip() {
                             7 ^ tile_offset_y
                         } else {
                             tile_offset_y

src/display/structs.rs

@@ -11,15 +11,19 @@ impl BgMapAttributes {
     }
 
     pub fn horizontal_flip(&self) -> bool {
-        (self.0 >> 5) != 0
+        ((self.0 >> 5) & 1) == 1
     }
 
     pub fn vertical_flip(&self) -> bool {
-        (self.0 >> 6) != 0
+        ((self.0 >> 6) & 1) == 1
+    }
+
+    pub fn has_priority(&self) -> bool {
+        (self.0 >> 7) != 0
     }
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub enum PixelOrigin {
     Empty,
     Background(usize),
@@ -36,7 +40,7 @@ pub struct Sprite {
 
 impl Sprite {
     pub fn load(buf: &[u8]) -> Self {
-        assert!(buf.len() > 4);
+        assert!(buf.len() >= 4);
         Self {
             x: buf[0],
             y: buf[1],