Fix PPU LY on VBlank

IsaacMarovitz · Dec 14, 2023 · 18e6a2f · 18e6a2f
1 parent 366c31b
commit 18e6a2f
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Showing 2 changed files with 20 additions and 7 deletions.
diff --git a/src/mmu.rs b/src/mmu.rs
@@ -90,6 +90,7 @@ impl Memory for MMU {
             0xFF10..=0xFF3F => 0x00,
             0xFF0F => self.intf.bits(),
             0xFF70 => self.wram_bank as u8,
+            0xFEA0..=0xFEFF => 0xFF,
             0xFFFF => self.inte.bits(),
             _ => panic!("Read to unsupported address ({:#06x})!", a),
         }
@@ -117,6 +118,8 @@ impl Memory for MMU {
             0xFF0F => self.intf = Interrupts::from_bits(v).unwrap(),
             0xFF50 => {},
             0xFF70 => self.wram_bank = match v & 0x07 { 0 => 1, n => n as usize },
+            0xFEA0..=0xFEFF => {},
+            0xFF7F => {},
             0xFFFF => self.inte = Interrupts::from_bits_truncate(v),
             _ => panic!("Write to unsupported address ({:#06x})!", a),
         }

diff --git a/src/ppu.rs b/src/ppu.rs
@@ -10,6 +10,7 @@ pub struct PPU {
     mode: GBMode,
     ppu_mode: PPUMode,
     cycle_count: u32,
+    vblanked_lines: u32,
     sy: u8,
     sx: u8,
     ly: u8,
@@ -99,6 +100,7 @@ impl PPU {
             mode,
             ppu_mode: PPUMode::OAMScan,
             cycle_count: 0,
+            vblanked_lines: 0,
             sy: 0x00,
             sx: 0x00,
             ly: 0x00,
@@ -185,14 +187,21 @@ impl PPU {
                 false
             },
             PPUMode::VBlank => {
-                if self.cycle_count > 4560 {
-                    self.cycle_count -= 4560;
-                    self.ly = 0;
-                    self.ppu_mode = PPUMode::OAMScan;
-                    if self.lcds.contains(LCDS::MODE_2_SELECT) {
-                        self.interrupts |= Interrupts::LCD;
+                if self.cycle_count > 456 {
+                    self.cycle_count -= 456;
+                    self.vblanked_lines += 1;
+
+                    if self.vblanked_lines >= 10 {
+                        self.vblanked_lines = 0;
+                        self.ly = 0;
+                        self.ppu_mode = PPUMode::OAMScan;
+                        if self.lcds.contains(LCDS::MODE_2_SELECT) {
+                            self.interrupts |= Interrupts::LCD;
+                        }
+                        // println!("[PPU] Switching to OAMScan!");
+                    } else {
+                        self.ly += 1;
                     }
-                    // println!("[PPU] Switching to OAMScan!");
                 }
                 false
             }
@@ -462,6 +471,7 @@ impl Memory for PPU {
             0xFF43 => self.sx = v,
             0xFF44 => print!("Attempted to write to LY!"),
             0xFF45 => self.lc = v,
+            0xFF46 => {},
             0xFF47 => self.bgp = v,
             0xFF48 => self.op0 = v,
             0xFF49 => self.op1 = v,