fix off-by-one error when for scanline number

jonathanballs · Oct 4, 2024 · d3f1957 · d3f1957
1 parent 9601f80
commit d3f1957
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/src/mmu/ppu.rs b/src/mmu/ppu.rs
@@ -85,13 +85,13 @@ impl PPU {
 
             // Full line takes 114 ticks
             if self.modeclock >= 456 {
+                self.modeclock -= 456;
+                self.ly = (self.ly + 1) % 154;
+
                 if self.ly < SCREEN_HEIGHT as u8 {
                     self.render_scanline(self.ly);
                 }
 
-                self.modeclock -= 456;
-                self.ly = (self.ly + 1) % 154;
-
                 // Enter mode 1 (VBLANK)
                 if self.ly == 144 {
                     self.vblank_irq = true