1 files changed, 40 insertions, 0 deletions
diff --git a/src/block/screendescriptor.rs b/src/block/screendescriptor.rs
new file mode 100644
index 0000000..d53d252
--- /dev/null
+++ b/src/block/screendescriptor.rs
@@ -0,0 +1,40 @@
+pub struct ScreenDescriptor {
+	pub width: u16,
+	pub height: u16,
+	pub packed: u8,
+	pub background_color_index: u8,
+	pub pixel_aspect_ratio: u8
+}
+
+impl ScreenDescriptor {
+	pub fn color_table_present(&mut self, is_present: bool) {
+		if is_present {
+			self.packed |= 0b1000_0000;
+		} else {
+			self.packed &= 0b0111_1111;
+		}
+	}
+
+	pub fn color_table_size(&mut self, size: u8) {
+		// GCT size is calulated by raising two to this number plus one,
+		// so we have to work backwards.
+		let size = (size as f32).log2().ceil() - 1f32;
+		self.packed |= size as u8;
+	}
+
+	//TODO: Setter for sort flag in packed field
+	//TODO: Setter for color resolution in packed field
+}
+
+impl From<&ScreenDescriptor> for Box<[u8]> {
+	fn from(lsd: &ScreenDescriptor) -> Self {
+		let mut vec = vec![];
+		vec.extend_from_slice(&lsd.width.to_le_bytes());
+		vec.extend_from_slice(&lsd.height.to_le_bytes());
+		vec.push(lsd.packed);
+		vec.push(lsd.background_color_index);
+		vec.push(lsd.pixel_aspect_ratio);
+
+		vec.into_boxed_slice()
+	}
+}
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