Corrected bug: CPU can not index into second attr map

TylerBloom · Oct 28, 2024 · d142030 · d142030
1 parent b0e93b3
commit d142030
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Showing 3 changed files with 22 additions and 9 deletions.
diff --git a/spirit/src/mem/mod.rs b/spirit/src/mem/mod.rs
@@ -408,16 +408,15 @@ impl Index<WindowTileMapIndex> for MemoryMap {
             second_map: check_bit_const::<6>(self.io.lcd_control),
             // TODO: Not sure if this needs to be wrapping. Also, how are the X and Y bounds (< 143
             // and 166, respectively) are honored. Probably should be controlled on writes...
-            x: x.wrapping_sub(self.io.window_position[1]),
+            x: x.wrapping_sub(self.io.window_position[1].wrapping_sub(7)),
             y,
         };
-        if y == 0 {
+        if y == 16 {
             let BgTileMapInnerIndex { second_map, x, y } = index;
             println!("The window position: {:?}", self.io.window_position);
             let x = x as usize / 8;
             let y = y as usize / 8;
-            let index = 0x9800 + (second_map as usize * 0x400) + (y * 32) + x;
-            println!("Rendering the first window line. Indexing into the {}th map at 0x{index:0>4X} = 0x9800 + 0x{y:0>4x} * 32 + 0x{x:0>4x}", second_map as usize);
+            println!("Rendering the first window line. Indexing into the {}th tile map at ({x}, {y})", second_map as usize);
         }
         &self.vram[index]
     }
@@ -436,9 +435,16 @@ impl Index<WindowTileMapAttrIndex> for MemoryMap {
             second_map: check_bit_const::<6>(self.io.lcd_control),
             // TODO: Not sure if this needs to be wrapping. Also, how are the X and Y bounds (< 143
             // and 166, respectively) are honored. Probably should be controlled on writes...
-            x: x.wrapping_sub(self.io.window_position[1]),
+            x: x.wrapping_sub(self.io.window_position[1].wrapping_sub(7)),
             y,             //.wrapping_add(self.io.window_position[0]),
         };
+        if y == 16 {
+            let BgTileMapAttrInnerIndex { second_map, x, y } = index;
+            println!("The window position: {:?}", self.io.window_position);
+            let x = x as usize / 8;
+            let y = y as usize / 8;
+            println!("Rendering the first window line. Indexing into the {}th attr map at ({x}, {y})", second_map as usize);
+        }
         &self.vram[index]
     }
 }

diff --git a/spirit/src/mem/vram.rs b/spirit/src/mem/vram.rs
@@ -102,7 +102,7 @@ impl Index<CpuVramIndex> for VRam {
         if self.status.is_drawing() {
             &DEAD_READ_ONLY_BYTE
         } else {
-            if bank && index < 0x9C00 {
+            if bank {
                 &self.vram[1][index as usize - 0x8000]
             } else {
                 &self.vram[0][index as usize - 0x8000]
@@ -118,9 +118,15 @@ impl IndexMut<CpuVramIndex> for VRam {
             self.dead_byte = 0xFF;
             &mut self.dead_byte
         } else {
-            if bank && index < 0x9C00 {
+            if bank {
+                if index == 0x9C00 {
+                    println!("CPU is writing to (0, 0) in the second attr map.");
+                }
                 &mut self.vram[1][index as usize - 0x8000]
             } else {
+                if index == 0x9C00 {
+                    println!("CPU is writing to (0, 0) in the first attr map.");
+                }
                 &mut self.vram[0][index as usize - 0x8000]
             }
         }

diff --git a/spirit/src/ppu.rs b/spirit/src/ppu.rs
@@ -321,8 +321,9 @@ impl BackgroundFiFo {
     fn tick(&mut self, mem: &MemoryMap) {
         let bg = self.background.is_empty().then(|| &mut self.background);
         self.window.triggered =
-            self.y >= mem.io().window_position[0] && self.x + 8 >= mem.io().window_position[1];
-        let do_window = self.window.triggered && check_bit_const::<5>(mem.io().lcd_control);
+            self.y >= mem.io().window_position[0] && check_bit_const::<5>(mem.io().lcd_control);
+        let do_window =
+            self.window.triggered && self.x >= mem.io().window_position[1].wrapping_sub(15);
         self.window.was_used |= do_window;
         self.fetcher
             .tick(self.y, mem, bg, do_window.then_some(self.window));