Only draw frame_buffer if GPU drew

IsaacMarovitz · Dec 11, 2023 · 9cd1052 · 9cd1052
1 parent ed91e29
commit 9cd1052
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Showing 2 changed files with 14 additions and 6 deletions.
diff --git a/src/gpu.rs b/src/gpu.rs
@@ -102,27 +102,31 @@ impl GPU {
         }
     }
 
-    pub fn cycle(&mut self, cycles: u32) {
+    pub fn cycle(&mut self, cycles: u32) -> bool {
         if !self.lcdc.contains(LCDC::LCD_ENABLE) {
-            return;
+            return false;
         }
 
         self.cycle_count += cycles;
 
-        match self.ppu_mode {
+        return match self.ppu_mode {
             PPUMode::OAMScan => {
                 if self.cycle_count > 80 {
                     self.cycle_count -= 80;
                     self.ppu_mode = PPUMode::Draw;
                     println!("[PPU] Switching to Draw!");
                 }
+                false
             },
             PPUMode::Draw => {
                 // TODO: Allow variable length Mode 3
                 if self.cycle_count > 172 {
                     self.ppu_mode = PPUMode::HBlank;
                     self.draw_bg();
                     println!("[PPU] Switching to HBlank!");
+                    true
+                } else {
+                    false
                 }
             },
             PPUMode::HBlank => {
@@ -138,6 +142,7 @@ impl GPU {
                         println!("[PPU] Switching to OAMScan!");
                     }
                 }
+                false
             },
             PPUMode::VBlank => {
                 if self.cycle_count > 4560 {
@@ -146,6 +151,7 @@ impl GPU {
                     self.ppu_mode = PPUMode::OAMScan;
                     println!("[PPU] Switching to OAMScan!");
                 }
+                false
             }
         }
     }

diff --git a/src/main.rs b/src/main.rs
@@ -65,10 +65,12 @@ async fn main() -> Result<(), impl std::error::Error> {
 
             loop {
                 let cycles = cpu.cycle();
-                cpu.mem.gpu.cycle(cycles);
+                let did_draw = cpu.mem.gpu.cycle(cycles);
                 // TODO: This is WAY too slow
-                let frame_buffer = cpu.mem.gpu.frame_buffer.into_iter().flatten().flatten().collect();
-                context.lock().unwrap().update(frame_buffer);
+                if did_draw {
+                    let frame_buffer = cpu.mem.gpu.frame_buffer.into_iter().flatten().flatten().collect();
+                    context.lock().unwrap().update(frame_buffer);
+                }
 
                 sleep(Duration::from_millis((1000_f64 / 4_194_304_f64 * cycles as f64) as u64)).await;
             }