Implement force blank and master brightness

src/snes/ppu/bus.rs

@@ -87,11 +87,10 @@ where
         match bank {
             // System area
             0x00..=0x3F | 0x80..=0xBF => match addr {
+                // INIDISP - Display Control 1 (W)
+                0x2100 => Some(self.inidisp = val),
                 // OBSEL - Object Size and Object Base
-                0x2101 => {
-                    println!("OBSEL = {}", val);
-                    Some(self.obsel = val)
-                }
+                0x2101 => Some(self.obsel = val),
                 // OAMADDL - OAM Address and Priority Rotation (W)
                 0x2102 => {
                     let v = self.oamadd.get() & 0xFF00;

src/snes/ppu/mod.rs

@@ -122,6 +122,8 @@ pub struct PPU<TRenderer: Renderer> {
     oamadd: Cell<u16>,
     oam: [u8; OAM_SIZE],
     oam_writebuf: u8,
+
+    inidisp: u8,
 }
 
 #[derive(Debug)]
@@ -196,6 +198,8 @@ where
             oamadd: Cell::new(0),
             oam: [0; OAM_SIZE],
             oam_writebuf: 0,
+
+            inidisp: 0,
         }
     }
 

src/snes/ppu/render.rs

@@ -8,10 +8,25 @@ where
 {
     fn cgram_to_color(&self, addr: u8) -> Color {
         let entry = self.cgram[addr as usize];
-        (
+
+        if self.inidisp & 0x80 != 0 {
+            // Force blank
+            return (0, 0, 0);
+        }
+
+        let (r, g, b) = (
             (((entry >> 0) & 0x1F) as u8) << 3,  // Red, 5-bit
             (((entry >> 5) & 0x1F) as u8) << 3,  // Green, 5-bit
             (((entry >> 10) & 0x1F) as u8) << 3, // Blue, 5-bit
+        );
+
+        // Apply master brightness
+        let brightness = f32::from(self.inidisp & 0x0F) / 15.0_f32;
+
+        (
+            (f32::from(r) * brightness).to_u8().unwrap(),
+            (f32::from(g) * brightness).to_u8().unwrap(),
+            (f32::from(b) * brightness).to_u8().unwrap(),
         )
     }
 
@@ -72,6 +87,10 @@ where
         line_paletted: &mut [Color],
         priority: u8,
     ) {
+        if (self.tm | self.ts) & (1 << 4) == 0 {
+            return;
+        }
+
         for idx in 0..OAM_ENTRIES {
             let e = self.get_oam_entry(idx);