fix: switching of the LCD

examples/sdl/src/main.rs

@@ -89,10 +89,10 @@ fn main() {
     //game_boy.load_rom_file("../../res/roms.prop/alleyway.gb");
 
     //game_boy.load_rom_file("../../res/roms/firstwhite.gb");
-    //game_boy.load_rom_file("../../res/roms/opus5.gb");
+    game_boy.load_rom_file("../../res/roms/opus5.gb");
 
     //game_boy.load_rom_file("../../res/roms/paradius/cpu/01-special.gb"); // PASSED
-    game_boy.load_rom_file("../../res/roms/paradius/cpu/02-interrupts.gb");
+    //game_boy.load_rom_file("../../res/roms/paradius/cpu/02-interrupts.gb"); // PASSED
     //game_boy.load_rom_file("../../res/roms/paradius/cpu/03-op sp,hl.gb"); // PASSED
     //game_boy.load_rom_file("../../res/roms/paradius/cpu/04-op r,imm.gb"); // PASSED
     //game_boy.load_rom_file("../../res/roms/paradius/cpu/05-op rp.gb"); // PASSED

src/cpu.rs

@@ -109,6 +109,14 @@ impl Cpu {
             panic!("Invalid PC area at 0x{:04x}", pc);
         }
 
+        // @todo this is so bad, need to improve this by an order
+        // of magnitude
+        if self.halted {
+            if ((self.mmu.ie & 0x01 == 0x01) && self.mmu.ppu().int_vblank()) || ((self.mmu.ie & 0x04 == 0x04) && self.mmu.timer().int_tima()) {
+                self.halted = false;
+            }
+        }
+
         if self.ime {
             // @todo aggregate all of this interrupts in the MMU
             if (self.mmu.ie & 0x01 == 0x01) && self.mmu.ppu().int_vblank() {
@@ -179,7 +187,7 @@ impl Cpu {
 
         if *instruction_str == "! UNIMP !" || *instruction_str == "HALT" {
             if *instruction_str == "HALT" {
-                println!("Waiting for 0x{:02x} in HALT", self.mmu.ie);
+                println!("HALT with IE=0x{:02x} IME={}", self.mmu.ie, self.ime);
             }
             println!(
                 "{}\t(0x{:02x})\t${:04x} {}",

src/ppu.rs

@@ -316,10 +316,6 @@ impl Ppu {
     }
 
     pub fn clock(&mut self, cycles: u8) {
-        if !self.switch_lcd {
-            return;
-        }
-
         // increments the current mode clock by the provided amount
         // of CPU cycles (probably coming from a previous CPU clock)
         self.mode_clock += cycles as u16;
@@ -416,6 +412,13 @@ impl Ppu {
                 self.switch_window = value & 0x20 == 0x20;
                 self.window_map = value & 0x40 == 0x40;
                 self.switch_lcd = value & 0x80 == 0x80;
+
+                // in case the LCD is off takes the opportunity
+                // to clear the screen, this is the expected
+                // behaviour for this specific situation
+                if !self.switch_lcd {
+                    self.clear_frame_buffer();
+                }
             }
             0x0041 => {
                 self.stat_hblank = value & 0x04 == 0x04;
@@ -579,6 +582,9 @@ impl Ppu {
     }
 
     fn render_line(&mut self) {
+        if !self.switch_lcd {
+            return;
+        }
         if self.switch_bg {
             self.render_background();
         }