fix: more issues related to bad PPU handling

CHANGELOG.md

@@ -17,7 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
-*
+* More issues related with bad PPU handling
 
 ## [0.5.6] - 2022-11-17
 

src/ppu.rs

@@ -417,7 +417,7 @@ impl Ppu {
                     // registers make sense (are within range), the window
                     // switch is on and the line in drawing is above WY
                     if self.switch_window
-                        && self.wx - 7 < DISPLAY_WIDTH as u8
+                        && self.wx as i16 - 7 < DISPLAY_WIDTH as i16
                         && self.wy < DISPLAY_HEIGHT as u8
                         && self.ly >= self.wy
                     {
@@ -468,7 +468,7 @@ impl Ppu {
 
     pub fn read(&mut self, addr: u16) -> u8 {
         match addr {
-            0x8000..=0x97ff => self.vram[(addr & 0x1fff) as usize],
+            0x8000..=0x9fff => self.vram[(addr & 0x1fff) as usize],
             0xfe00..=0xfe9f => self.oam[(addr & 0x009f) as usize],
             0xff80..=0xfffe => self.hram[(addr & 0x007f) as usize],
             0xff40 => {